Galvanomirror unit

Claim 2

A galvanomirror unit comprising a galvanomirror for reflecting a laser beam, a driving mechanism which varies a direction of said galvanomirror to adjust the direction of light reflected by said galvanomirror, wherein said driving mechanism comprises: a torsion spring to which said galvanomirror is secured, said torsion spring being made of a leaf spring and having a major surface lying in a plane substantially parallel with a direction of gravity when in a free state, and means for mounting said torsion spring to a support structure, said mounting means including a spheric zone section defined with respect to one of said support structure and said torsion spring, and a mating recess defined with respect to the other one of said support structure and said torsion spring.

Claim 3

A galvanomirror unit according to claim 1, comprising: an immovable portion to which opposite ends of said torsion spring are secured.

Claim 4

A galvanomirror unit according to claim 2, wherein said galvanomirror is secured to an intermediate portion of said torsion spring.

Claim 5

A galvanomirror unit according to claim 2, further comprising: an electromagnetic drive mechanism provided between said torsion spring and said immovable portion to twist said torsion spring and thereby change the direction of said galvanomirror.

Claim 6

A galvanomirror unit according to claim 4, further comprising: a housing and a retainer, wherein said retainer is secured to said housing to support said galvanomirror.

Claim 7

A galvanomirror unit according to claim 5, wherein said immovable portion is made of a yoke which is supported on said retainer and adjustable with respect to said retainer.

Claim 8

A galvanomirror unit according to claim 6, wherein said retainer comprises: a pair of orthogonal surfaces which are oriented at 45° angles with respect to said torsion spring.

Claim 9

A galvanomirror unit according to claim 7, wherein said housing comprises: a pair of wall surfaces against which said corresponding orthogonal surfaces of said retainer abut.

Claim 10

A galvanomirror unit according to claim 7, further comprising: an initial position adjusting mechanism between said retainer and said yoke including an abutting portion provided on a surface of said yoke opposed to said galvanomirror, said abutting portion being in a shape of a spheric zone section, wherein a center of an imaginary sphere, of which said spheric zone is a part, lies in a plane of a reflecting surface of said galvanomirror, a recess provided on said retainer to come into contact with said abutting portion, and a fastening device for fastening said yoke and said retainer.

Claim 11

A galvanomirror unit according to claim 9, wherein said fastening device comprises: three adjusting screws which are screwed in said yoke through said retainer.

Claim 12

A galvanomirror unit according to claim 10, wherein said three adjusting screws are located at corners of an isosceles equilateral triangle.

Claim 13

A galvanomirror unit according to claim 11, wherein two of said three adjusting screws are positioned to form a right angle with a center of said abutting portion, a corner of said right angle being located at said center of said abutting portion.

Claim 14

A galvanomirror unit according to claim 12, wherein a remaining adjusting screw is provided thereon with a compression spring to bring said yoke and said retainer into contact with each other.

Claim 15

A galvanomirror unit according to claim 13, wherein said three adjusting screws are located inside a circular portion of said recess in contact with said abutting portion of said yoke.

Claim 16

A galvanomirror unit according to claim 4, further comprising: an electromagnetic rotating mechanism provided between said torsion spring and said an immovable portion to adjust the direction of the galvanomirror.

Claim 17

The galvanomirror unit according to claim 1, further comprising a yoke to which said torsion spring is mounted, said mounting means including a spheric zone section positioned on one of said support structure and said yoke, and a mating recess positioned on the other one of said support structure and said yoke.

Claim 18

An optical disc apparatus comprising: a laser source for emitting a laser beam; a galvanomirror unit which includes a galvanomirror for reflecting the laser beam onto an optical disc; and a driving mechanism which adjusts a position of said galvanomirror to change a direction a light reflected by said galvanomirror, said driving mechanism having a torsion spring to which said galvanomirror is secured, said torsion being made of a leaf spring and having a major surface lying in a plane substantially parallel with a direction of gravity when in a free state, and means for mounting said torsion spring to a support structure, said mounting means including a spheric zone section defined with respect to one of said support structure and said torsion spring, and a mating recess defined with respect to the other one of said support structure and said torsion spring.

Claim 19

An optical disc apparatus comprising: a laser source for emitting a laser beam; a galvanomirror unit which includes a galvanomirror for reflecting the laser beam onto an optical disc; and a driving mechanism which adjusts a position of said galvanomirror to change a direction a light reflected by said galvanomirror, said driving mechanism having a torsion spring to which said galvanomirror is secured, said torsion being made of a leaf spring and having a major surface lying in a plane substantially parallel with a direction of gravity when in a free state, and means for mounting said torsion spring to a support structure, said mounting means including a spheric zone section defined with respect to one of said support structure and said torsion spring, and a mating recess defined with respect to the other one of said support structure and said torsion spring.

Claim 20

An optical disc apparatus according to claim 17, wherein the galvanomirror reflects said laser beam emitted from said laser source to make the laser beam incident upon said optical disc.

Claim 21

An optical disc apparatus according to claim 18, further comprising: an objective lens which converges the laser beam onto a predetermined track after being reflected by said galvanomirror in a radial direction of said optical disc.

Claim 22

An optical disc apparatus according to claim 19, further comprising: a reflecting mirror for reflecting said laser beam reflected by said galvanomirror toward said objective lens.

Claim 23

An optical disc apparatus according to claim 20, wherein said reflecting mirror and said objective lens are together movable in said radial direction of said optical disc.

Claim 24

The optical disc apparatus according to claim 17, further comprising a yoke to which said torsion spring is mounted, said mounting means including a spheric zone section positioned on one of said support structure and said yoke, and a mating recess positioned on the other one of said support structure and said yoke.

Claim 25

An optical disc apparatus comprising: a light gathering optical system for gathering a laser beam onto a laser disc; and a galvanomirror unit within said light gathering optical system, including a galvanomirror whose angular position is adjusted to accurately collect the laser beam onto a predetermined track of said optical disc in accordance with a tracking error signal corresponding to an off-set value of said laser beam from said track; said galvanomirror unit having a torsion spring to which said galvanomirror is secured, said torsion spring being made of a leaf spring and having a major surface lying in a plane substantially parallel with a direction of gravity when in a free state, and means for mounting said torsion spring to a support structure, said mounting means including a spheric zone section defined with respect to one of said support structure and said torsion spring and a mating recess defined with respect to the other one of said support structure and said torsion spring.

Claim 26

An optical disc apparatus comprising: a light gathering optical system for gathering a laser beam onto a laser disc; and a galvanomirror unit within said light gathering optical system, including a galvanomirror whose angular position is adjusted to accurately collect the laser beam onto a predetermined track of said optical disc in accordance with a tracking error signal corresponding to an off-set value of said laser beam from said track; said galvanomirror unit having a torsion spring to which said galvanomirror is secured, said torsion spring being made of a leaf spring and having a major surface lying in a plane substantially parallel with a direction of gravity when in a free state, and means for mounting said torsion spring to a support structure, said mounting means including a spheric zone section defined with respect to one of said support structure and said torsion spring and a mating recess defined with respect to the other one of said support structure and said torsion spring.

Claim 27

An optical disc apparatus according to claim 23, comprising: an immovable portion to which opposite ends of said torsion spring are secured.

Claim 28

An optical disc apparatus according to claim 24, wherein said galvanomirror is secured to an intermediate portion of said torsion spring.

Claim 29

An optical disc apparatus according to claim 25, further comprising: an electromagnetic drive mechanism provided between said torsion spring and said immovable portion to twist said torsion spring and thereby change a direction of said galvanomirror.

Claim 30

The optical disc apparatus according to claim 23, further comprising a yoke to which said torsion spring is mounted, said mounting means including a spheric zone section positioned on one of said support structure and said yoke, and a mating recess positioned on the other one of said support structure and said yoke.

Claim 31

A galvanomirror unit in which a laser beam emitted from a laser source is reflected towards an objective lens which is linearly moved in a radial direction of an optical disc, comprising: a torsion spring in the form of a leaf spring which is supported at its opposite ends and having a major surface which lies in a plane substantially parallel with a direction of gravity; a galvanomirror which is supported on an intermediate portion of said torsion spring to be angularly deflected about a horizontal axis, and means for mounting said torsion spring to a support structure, said mounting means including a spheric zone section defined with respect to one of said support surface and said torsion spring, and a mating recess defined with respect to the other one of said support structure and said torsion spring.

Claim 32

A galvanomirror unit in which a laser beam emitted from a laser source is reflected towards an objective lens which is linearly moved in a radial direction of an optical disc, comprising: a torsion spring in the form of a leaf spring which is supported at its opposite ends and having a major surface which lies in a plane substantially parallel with a direction of gravity; a galvanomirror which is supported on an intermediate portion of said torsion spring to be angularly deflected about a horizontal axis, and means for mounting said torsion spring to a support structure, said mounting means including a spheric zone section defined with respect to one of said support surface and said torsion spring, and a mating recess defined with respect to the other one of said support structure and said torsion spring.

Claim 33

The galvanomirror unit according to claim 28, further comprising a yoke to which said torsion spring is mounted, said mounting means including a spheric zone section positioned on one of said support structure and said yoke, and mating recess positioned on the other one of said support structure and said yoke.