Optical information recording and reproducing apparatus

Details Optical information recording and reproducing apparatus Optical information recording and reproducing apparatus

1999-12-08

2003-12-16

Tran, Thang V. (Department: 2653)

Dynamic information storage or retrieval

With servo positioning of transducer assembly over track...

Optical servo system

C369S126000, C369S112010

Reexamination Certificate

active

06665239

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical information recording and reproducing apparatus for performing an optical recording or optomagnetic recording with high density and large capacity, in particular, an optical information recording and reproducing apparatus for optically recording the information or optomagnetically recording the information with high density and large capacity such as the optical information recording and reproducing apparatus which is preferable for recording and reproducing the optical information with high density and high precision by use of the adjacent-field light (evanescent light), and for radiating the light from the tip end of the probe onto the optical information recording medium, and the optical information recording and reproducing apparatus applying the probe microscope.
2. Discussion of the Background
An optical information recording and reproducing apparatus for recording and reproducing the information with high density by use of the adjacent field light (evanescent light) has been already proposed.
Background Art 1 (for the First Invention)
For instance, in the published specification of Japanese Laid open Patent Publication No.7-192,280 (called “Background Art 1), a structure of the optical information recording and reproducing apparatus is proposed in
FIG. 14
as the structure capable of raising the accuracy of the tracking control and enabling to use a disc-state recording medium in the high-density recording/reproducing operation utilizing the above-mentioned evanescent light.
In such structure, a laser light radiated (emitted) from the semiconductor laser (laser diode)
1
is focused by a lens
6
, and the focused laser light is applied to an optical fiber
7
through an opening
8
thereof. A scanning head
9
formed on the tip end portion of the optical fiber
7
becoming thinner toward the tip end has an opening
10
of a diameter almost equal to or smaller than the wavelength of the laser light on the projecting end surface. A recording surface
11
moves relating to the opening
10
. A reflection light taken out from the recording surface
11
through the scanning head
9
is detected by a light detector
13
. A scanning control head
20
unitarily mounted in parallel with the scanning head
9
includes a semiconductor laser (laser diode)
15
employed as a peculiar (original) light source, a lens system, and optoelectric conversion element
19
, and generates a tracking error detecting signal for positioning the scanning head
9
onto the track of the recording surface
7
. An actuator
21
is controlled on the basis of the tracking error signal and thereby the tracking accuracy can be improved.
Background Art 2 (for the First-group Invention)
On the other hand, in the published specification of, Japanese Laid-open Patent Publication No.8-321,084 (called “Background Art 2”), a structure of the optical information recording and reproducing apparatus is proposed in
FIG. 15
as the structure capable of performing the positional control in the track width direction with high precision and performing the operation of recording/reproducing with high accuracy in the scanning type probe memory technology. In
In such structure, tracking probes
51
and
56
are provided adjacently to probes
52
through
55
in order to record and reproduce the information on a recording area
64
. The positional control in the track width direction of the probes
52
through
55
for use in recording or reproducing is performed by a probe actuator
65
on the basis of the tracking error signal detected by the tracking probes
51
and
56
, and thereby the positional control in the track width direction can be performed with high accuracy.
In the above-mentioned background arts 1 and 2, since the information is written in on the recording medium by use of the adjacent field light, the size of the recorded mark becomes almost several tens n m in the diameter thereof. Consequently, it is necessary to set the accuracy of the tracking for precisely writing in and reading out the recorded mark suitably to an extent of several nm.
However, although the above background arts 1 and 2 describe the detection medium for detecting the tracking error signal, those arts do not describe any concrete structure for finely moving (actuating) the probe in order to compensate the tracking error.
Background Art 3 (for the Second-group Invention)
The background art 3 described in the published specification of Japanese Laid-open Patent Publication No.7-192,280 raises the accuracy of the tracking control in the high-density recording/reproducing by use of the evanescent light, and enables to use the disc-state recording medium.
For this reason, as shown in
FIG. 17
, a laser light radiated (emitted) from the semiconductor laser (laser diode)
201
is focused by a lens
202
, and the focused laser light is applied to an optical fiber
203
through an opening
204
thereof. A scanning head
205
formed on the tip end portion of the optical fiber
203
becoming thinner toward the tip end has an opening
206
of a diameter almost equal to or smaller than the wavelength of the laser light on the projecting end surface. A recording surface
207
of the recording medium moves relatively to the opening
206
. A reflection light taken out from the recording surface
207
through the scanning head
205
is detected by a light detector
208
. A scanning control head
209
unitarily mounted in parallel with the scanning head
205
includes a semiconductor laser (laser diode)
210
employed as a peculiar (original) light source, a lens system, and optoelectric conversion element
217
, and generates a tracking error detecting signal for positioning the scanning head
205
onto the track of the recording surface
207
.
Background Art 4 (for the Second-group Invention)
The background art 4 described in the published specification of Japanese Patent Publication No, 8-321,084 performs the positional control in the track width direction with high accuracy in the scanning type probe memory technology and thereby performs the operation of recording or reproducing with high accuracy.
For this reason, as shown in
FIG. 18
, tracking probes
215
and
216
are provided adjacently to probes
211
through
214
for use in recording or reproducing the optical information. The positional control of the probes
211
through
214
for use in recording/reproducing in the track width direction is performed by the tracking error signal detected by the tracking probes
215
and
216
.
Background Art 5 (for the second-group Incention)
The background art 5 described in the published specification of Japanese Patent Publication NO. 8-7323 provides an ultrahigh-density and small-size optical information recording and reproducing apparatus.
For this reason, as shown in
FIG. 19
, a semiconductor laser (laser diode)
221
, a light detector
222
, and an evanescent light generating probe
223
are respectively carried on a floating (surfacing) slider
224
. The information is recorded on the recording medium
226
by the action of the evanescent light
225
. When the information is reproduced, the electric current value of the semiconductor laser is biased with the threshold value, and as the result the S/N ratio can be improved.
The operation of tracking is performed in such way as mentioned below. Namely, as shown in
FIG. 20
(FIGS.
20
A and
20
B), by use of the probe shown in
FIG. 19
, the evanescent light is formed in the track direction (the circular circumferential direction of the medium
226
), and the light beam having a little (somewhat) spreading-out width is formed in the direction perpendicular to the track direction. It is preferable that the ratio of those two light beams diameters is 5:1. There exist a servo area
228
having previously formed prepit
227
and the data area
229
. The prepit
227
is a wobble pit having a center respectively disposed on a place displaced right and left by a constant when the surface of the wobble pit

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