Dynamic information storage or retrieval – Dynamic mechanism subsystem – Specific detail of storage medium support or motion production
Reexamination Certificate
1997-11-12
2001-04-03
Miller, Brian E. (Department: 2153)
Dynamic information storage or retrieval
Dynamic mechanism subsystem
Specific detail of storage medium support or motion production
Reexamination Certificate
active
06212157
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for suppressing warping of an optical disk during its rotary driving, and an optical disk apparatus equipped with such an apparatus for suppressing warping.
FIG. 1
is a perspective view showing a constitution of an essential part of a conventional magnetic field modulation type optical disk apparatus. In the drawing, numeral
53
denotes a carriage that is approximately L-shaped in lateral side view. Numerals
41
,
41
denote guide shafts to guide the carriage
53
. The carriage
53
is formed of: (1) a carriage body
54
of rectangular parallelepiped which is long in the radial direction of a donut shaped optical disk
2
(which is driven in rotation by a rotary spindle)
1
; and (2) a supporting part
55
which is located at the end part of the outer peripheral side (front side) of the optical disk
2
, where this supporting part extends upright of the carriage body
54
. A load arm
61
, to be described later, is fixed to the upper end of the supporting part
55
.
The guide shafts
41
,
41
are provided on one side of the optical disk
2
at a predetermined distance in parallel with each other so that the center line between the two guide shafts
41
,
41
is in the radial direction of the optical disk
2
. The carriage body
54
is provided with two through-holes having approximately the same diameters as those of the guide shafts
41
,
41
, the through-holes penetrating through the carriage body
54
from its front to the back side (the inner peripheral side of the optical disk
2
) in parallel with each other at a predetermined distance. By letting the guide shafts
41
,
41
through the through-holes, the carriage
53
is swingably supported in the radial direction of the optical disk
2
.
At the central lower part in front of the carriage body
54
there is provided a light conductive hole
56
for leading light beam B in parallel with the through-hole so as to allow the light beam B from a fixed light source disposed opposite to the light conductive hole
56
to be incident in the light conductive hole
56
. On the back side of the carriage body
54
there is provided an opening communicating with the light conductive hole
56
, and a lens holder
81
is held in cantilever at an end of the front side of the opening. The lens holder
81
has a rectangular tubular shape which has opening vertically and is longer in the thickness direction of the carriage body
54
when viewed from the side. On the upper and lower faces of the end of the front side of the opening there are fixed the base parts of the flat springs
84
having the U-shaped notches, respectively, and the apexes of the flat springs
84
are fixed to the upper and lower faces of the lens holder
81
on the front side.
On the front side in the lens holder
81
, an objective lens
82
is fixed in parallel with the upper face of the carriage body
54
. The objective lens
82
condenses the light beam B that is reflected upwardly by a reflecting mirror disposed opposite below the objective lens
82
and emits it to the optical disk
2
. The lens holder
81
is inserted at the back side of a leg of the U-shaped yoke
85
for focusing, which is fixed to the carriage body
54
. On the inner face of the other leg of the yoke
85
for focusing, a magnet
86
for focusing is fitted. Also, around the lens holder
81
a focus coil
83
is fitted which is wound multiple times around a shaft parallel with the optical axis of the objective lens
82
. The focus coil
83
is disposed orthogonal with a magnetic field formed by the magnet
86
for focusing and the yoke
85
for focusing. And, by leading electric current in the focus coil
83
, focus control is made to cause ascending or descending of the lens holder
81
which holds the objective lens
82
, and on which the focus coil
83
is wound, in the direction of the optical axis of the objective lens
82
.
The load arm
61
fixed to the upper end of the supporting part
55
is a flat spring, which extends from the upper end of the supporting part
55
toward the optical disk
2
by a predetermined size in parallel with the carriage body
54
, and from that place the load arm
61
is inclined toward the optical disk
2
at a predetermined angle of inclination. The tip of the load arm
61
is acute, and is situated at the predetermined position above the lens holder
81
. Also, the tip is made to be movable up and down by a lift device. To the tip of the load arm
61
there is fitted, in a swingable manner, a slider
71
having a rectangular shape in plan view so that the optical disk
2
is set between the slider
71
and the lens holder
81
. To the lower face of the slider
71
there is fixed a magnetic head
70
made by winding a coil around a core so as to be positioned at the center of the objective lens
82
. The slider
71
is in direct contact with the surface of the optical disk
2
when the optical disk
2
is in a still state.
By the air current generated by the rotary driving of the optical disk
2
, buoyancy is generated on the slider
71
, but as a force directed toward the optical disk
2
is exerted to the slider
71
side by the spring force of the load arm
61
, the slider
71
floats at the position where the two items are balanced. The buoyancy as described above is strong when the distance between the slider
71
and the optical disk
2
is short, and weak when the distance is long. On the other hand, the force to be exerted to the slider
71
from the load arm
61
is weak when the distance between the slider
71
and the optical disk
2
is short, and strong when the distance is long. Accordingly, during the rotation of the optical disk
2
, the distance between the slider
71
and the optical disk
2
is kept constant.
On the back side portions of both sides of the carriage body
54
there are fixed tubular drive coils
44
,
44
wound in multiple turns around a shaft in parallel with the guide shafts
41
,
41
. Also, on both sides of the carriage body
54
, there are disposed the frame shaped yokes
42
,
42
which are open up and down and long in the lengthwise direction of the guide shafts
41
,
41
in a manner that the lateral surfaces in the longitudinal direction of the two yokes
42
,
42
and the lateral surfaces of the carriage body
54
are in parallel with one another. On the respective side walls opposite to the carriage body
54
of the two yokes
42
,
42
, the drive coils
44
,
44
are externally accommodated without contact. On the inner surface of the other side walls respectively of the two yokes
42
,
42
, there are fitted plate form magnets
43
,
43
having approximately the same length as those of the yokes
42
,
42
, so that a magnetic field formed by the magnets
43
,
43
and yokes
42
,
42
crosses at a right angle with parts of the drive coils
44
,
44
.
When the reciprocal current is led to the drive coils
44
,
44
, by the reciprocal actions with the magnetic field, the carriage
53
supporting the drive coils
44
,
44
advances or recedes in the lengthwise direction of the yokes
42
,
42
, i.e., in the radial direction of the optical disk
2
. By this step, there is performed an access control to converge the light beam B to be irradiated on the optical disk
2
from the objective lens
82
on the upper surface of the optical disk
2
and move its spot to the required track of the optical disk
2
, and a track control to have the spot of the light beam B follow the track of access. Alternatively, the track control can be realized by providing an actuator for moving the lens holder
81
to the radial direction of the optical disk
2
. At this time, the magnetic head
70
is always positioned at the center of the objective lens
82
because it is supported to the carriage
53
by the load arm
61
to which the slider
71
fixed with the magnetic head
70
is fixed.
And, while irradiating the light beam B of predetermined intensity on the recording face of the optical disk
2
while carrying out the controls as described above, a magn
Sato Tadashi
Yabuki Eiji
Fields Kenneth W.
Fujitsu Limited
Greer Burns & Crain Ltd.
Miller Brian E.
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