JPS60145538A - Optical recording and reproducing method and its device - Google Patents

Abstract

PURPOSE:To make a focus control unnecessary, and to improve a positioning accuracy of a recording medium by separating a mechanism for stabilizing a flexible recording medium and an optical head, and executing a tracking and a seeking in a state that the stabilizing mechanism is fixed. CONSTITUTION:A recording medium 40 is fixed to a revolving shaft 12 through a hub 11, and to its upper part, a fixed plate 41 having a transparent spherical part 42 is fixed. When the recording medium 40 rotates, the recording medium 40 is attracted to the fixed plate 41 by an air dynamic action, and profiled and deformed to a shape of the spherical part 42. On the other hand, a tracking and a seeking are realized by a rotation of only an optical head, a medium supporting system consisting of the recording medium 40, the fixed plate 41 and the spherical part 42 is not varied, and even if the optical head 20 rotates, a relative position relation of the optical head 20 and the recording medium 40 is constant, and accordingly, even if the tracking and the seeking are executed, an optical path length between the recording medium 40 and an objective 27 can be held at a fixed value with a high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an optical recording/reproducing method and apparatus thereof that do not require focus control and are capable of high-speed and highly accurate track positioning.

(Prior Art) Typical configuration examples of conventional devices of this type are shown in FIGS. 1 to 4. 1 and 2 show an optical recording and reproducing apparatus using a rigid disc-shaped recording medium, in which 10 is the recording medium described by MiJ, 11 is a hub for attaching the recording medium IO to a rotating shaft 12, and 13 2 is a motor that rotates the rotating shaft 12; 20 is an optical head; a laser light source 21;
2. Collimator lens 23, rotating mirror 24, or fixed mirror 2
4', semi-transparent mirrors 25, 26, objective lens 27, spring 28,
It consists of a voice coil 29, photodetectors 30 to 34, differential transformers 35 and 36, a focus control circuit 37.1 and a rack control circuit 38.

Incidentally, since the recording medium of these devices is rigid, it causes surface runout during one rotation due to warping due to processing errors and inclination due to mounting errors on the rotating shaft 12. Due to this surface wobbling, the distance between the objective lens 27 for converging the recording/reproducing light beam into a spot and the recording medium 10 fluctuates, so it is necessary to correct this by ±0.5 μm or more.
Second, a focusing mechanism capable of highly accurate positioning was required. For this purpose, for example NJ? The objective lens 27 was driven in a direction perpendicular to the medium surface using a coil 29. In addition, in the conventional device, not only the above-mentioned high-precision positioning mechanism is required, but also the objective lens 27 is necessarily elastically supported by the spring 28, so the objective lens 27 vibrates due to external disturbances, resulting in poor earthquake resistance. It also had drawbacks.

Tracking and seeking are performed by rotating the rotating mirror 24 as shown in the first factor or by rotating the optical head 24 as shown in FIG.
However, when the rotating mirror 24 rotates, as shown in FIG. This has disadvantages in that positioning accuracy decreases and the amount of reflected light received decreases, and in parallel movement, the movement mechanism is severely damaged, making the device expensive and having poor maneuverability during positioning. It had

FIG. 4 shows an optical recording/reproducing device using a conventional flexible recording medium, in which 40 is a disc-shaped flexible recording medium, 41 is a fixing plate, and 50 is a U-shaped ballast. be. In this device, the recording medium 4G is aerodynamically supported by the fixed plate 41 using the Bernoulli disk principle, and furthermore, by the airflow flowing into the narrow gap of the U-shaped ballast 50,
The surface wobbling of the recording medium 40 is removed without touching it, making focus control unnecessary. However, during tracking or seeking, since the U-shaped stabilizer 50 is integrated with the optical head 20, the U-shaped stabilizer 50 is
When the distance to zero changes, the circumferential speed and reaction force change, and the distance between the recording medium 40 and the objective lens 27 changes.When operating at high speed, vibration occurs and the recording medium 40 cannot be positioned with sufficient accuracy. It had the disadvantage that it was not. Furthermore, when seeking, it is necessary to move the U-shaped stabilizer 50 and the optical head 20 at the same time, which is not suitable for increasing speed.

(Object of the Invention) In view of the above-mentioned drawbacks, the object of the present invention is to eliminate the need for focus control, separate the mechanism for stabilizing the flexible recording medium from the optical head, and maintain the stabilizing mechanism at 1.11 points. The purpose is to improve the positioning accuracy of the recording medium and improve the performance of the apparatus by performing tracking and seeking.

(Configuration of 1 invention) In order to achieve the above-mentioned object, the 1st invention provides a flexible recording medium in which a laser beam is rotationally driven by an optical head.
In an optical recording and reproducing method for recording or reproducing a signal, the recording medium is partially and temporarily curved with the same curvature in a direction perpendicular to the track, and the center of curvature of the curved portion is The optical head is controlled to rotate in the perpendicular direction using the rotation axis as the rotation axis.In the second invention, the optical head converges the laser beam onto a flexible recording medium that is rotationally driven, and the signal is recorded. In an optical recording/reproducing device for recording or reproducing, a fixing plate is disposed close to one surface of the recording medium so as to aerodynamically support the recording medium, and a fixing plate is provided on a part of the fixing plate and the a spherical part that aerodynamically supports the recording medium in a curved state with the same curvature in a direction perpendicular to the track and transmits the laser beam; A drive section for controlling the rotation of the motor is provided.

(Embodiment) FIG. 5 shows an embodiment of the present invention, in which the same components as in the conventional example are denoted by the same reference numerals.

That is, 11 is a hub, 12 is a rotating shaft, 13 is a motor, 20 is an optical head, and a laser light source z1. It consists of a beam splitter 22, a collimator lens 23, a semi-transparent mirror 26, an objective lens 27, and photodetectors 32-34. 3
6 is a differential transformer, 38 is a track control circuit, 40 is a disc-shaped flexible recording medium, 41 is a fixed plate, 42 is a spherical part,
60 is a rotation axis of the optical head 2o, and 61 is a motor.

The recording medium 40 has a thickness of 10 to 100 μm, is fixed to the rotating shaft 12 via a hub 11, and is rotated by a motor 13 at 5 to 5 Q rps. Fixed plate 41
is perpendicular to the rotating shaft 12 and fixed at a position 10 to 1000 μm above the attachment point of the recording medium 40 to the hub 11 . A hole is provided in the fixing plate 40, and a circular spherical portion 42 made of a transparent material and having a spherical lower surface having the same curvature in the radial direction of the recording medium 4o is fixed inside the hole. The spherical portion 42 has a radius of curvature of 10 to 100, and its apex protrudes from the lower surface of the fixed plate 41 by 10 to 800 μm.

Above the fixed plate 4o, an optical head 2o is mounted on a rotating shaft 6o.
It is attached so that it rotates around the center. The light beam emitted by the laser light source 21 is transmitted to the beam splitter 2
2, collimator lens z3, semi-transparent mirror 26, objective lens 2
7, and is irradiated onto the recording medium 40 via the spherical portion 42, and is moved over the recording medium 40 in the radial direction by rotation of the optical head 2o around the rotation axis 60. . The position of the rotation axis 6o will be detailed later.
This coincides with the center of curvature of the recording medium 40 during rotation, and the focus of the objective lens 27 coincides with the surface of the recording medium 40 during rotation. The optical head 20 includes a semi-transparent mirror 26, a photodetector 32. : 311, the differential transformer 36, and the track control circuit 38 are used to detect the position of the light beam on the recording medium 4o by the already known three-spot method, diffraction method, etc., and the motor 61 is activated based on the error signal. The rotation of the optical head 20 is controlled to direct the light beam to the flexible recording medium 40.
The structure is such that it follows two desired tracks.

Next, the operation will be explained. First, when the recording medium 40 rotates, the recording medium 40 is attracted to the fixed plate 41 due to aerodynamic action. Furthermore, air is pushed into the wedge-shaped gap between the recording medium 40 and the recording medium 40 under the spherical portion 42 by its viscous force, increasing the pressure, and the recording medium 40 is deformed into a constant shape with an error of approximately ±0.1 μm. This deformed shape follows the shape of the spherical portion 42 because the thickness of the recording medium 40 is sufficiently thin, and can be regarded as a substantially spherical surface near its apex. On the other hand, dragging and seeking are realized by rotating only the optical head 20, and the spherical section 42 does not move. Therefore, the recording medium 40. Fixed plate 41. The medium support system consisting of the spherical portion 42 does not change and the shape of the medium remains constant. Broken rotating shaft 6
Since 0 coincides with the center of curvature of the recording medium 400 deformed by air pressure, the relative positional relationship between the optical head 20 and the recording medium 40 remains constant even if the optical head 20 rotates. Therefore, even when tracking and seeking are performed, the optical path length between the recording medium 40 and the objective lens 27 can be maintained at a constant value with high accuracy. Needless to say, the recording medium does not vibrate even during high-speed operation. As shown in FIG. 6, since the incident light A is always irradiated onto the recording medium 40 at right angles, there is no decrease in positioning accuracy or decrease in the amount of received light due to a change in the angle of incidence on the recording medium 40. Rotating shaft 60
The position of is uniquely determined by the deformed shape of the recording medium 40, the physical properties, size, rotational speed of the medium, the radius of curvature of the spherical portion 42, the protrusion from the fixed plate 41, and the distance from the center of the medium. It can be determined in advance by numerical analysis or experiment.

In the non-contact support mechanism that uses air dynamic pressure as described above, the air pressure becomes 0 when the medium stops, so
Normally, damage, dirt, etc. on both surfaces due to contact between the recording medium and the spherical surface during startup and shutdown causes a decline in recording and reproducing characteristics. However, as in this embodiment, the spherical portion 42 is placed upward, and the recording medium 4o
If the recording medium 40 is placed downward, the recording medium 40 will curve downward due to gravity when stopped, as shown in FIG. 7, and will not come into contact with the spherical portion 42.

If the external vibration is large and the shape of the recording medium 40 is not stable, as shown in FIG.
3 should be facing each other.

The stabilization technology using the opposing thrust plate 43 is disclosed in Patent No. 847.
No. 448, No. 847,449. If you want to make the spherical part of the twisted recording medium wider, as shown in FIG. Set i′1. Bye.

As is clear from the explanation in 1 and 2, the spherical part 42 for deforming the recording medium 40 does not necessarily have to be circular, and if the recording medium 4o is deformed in an arc shape in the radial direction, It may be of any shape. Figure 1O(a)
(L,) shows an example using a Rugby sole-like spherical portion 42'. However, the above-mentioned spherical portion 42 is the best in terms of ease of processing.

(Effects of the Invention) As explained above, the method of the present invention eliminates the need for focus control of the optical head and enables high-speed and highly accurate trunk positioning.
According to the device of the present invention, the mechanism for stabilizing the recording medium and the optical head are separated, and tracking and seeking can be performed with the stabilizing mechanism fixed, so trunking and seeking can also be done at high speed. This method has the advantage that it can be performed with high accuracy, and that it is easy to make the device smaller, lighter, and higher in performance.

[Brief explanation of the drawing]

1, 2, and 3 are block diagrams of a conventional optical recording/reproducing device, FIG. 4 is an explanatory diagram of the operation of section 1 (2), and FIG. 5 is a block diagram of embodiments of the present invention. , FIG. 6 is a detailed diagram of a part of FIG. 5, FIG. 7 is an explanatory diagram of the operation of FIG.
FIGS. 10(a) and 10(b) are configuration diagrams showing another embodiment of the present invention. 20... Optical head, 40... Flexible recording medium, 4
1-Identification plate, 42...Spherical part patent Applicant Nippon Telegraph and Telephone Public Corporation agent Patent attorney Yoshi 1) Takashi Seiji Figure 1 220 Figure 2 0 Figure 5 Figure 6 Figure 8 Figure 1 Figure 9

Claims (2)

[Claims] (1) In an optical recording and reproducing method in which a laser beam is focused on a flexible recording medium rotationally driven by an optical head to record or reproduce a signal, the recording medium is partially and temporarily removed from the trunk. An optical recording and reproducing method, characterized in that the optical head is curved with the same curvature in orthogonal directions, and the optical head is controlled to rotate in the orthogonal direction using the center of curvature of the curved portion as a rotation axis. (2) In an optical recording/reproducing device that records or reproduces a signal by converging a laser beam onto a flexible recording medium rotationally driven by an optical head, the recording medium is aerodynamically supported. a fixing plate disposed close to one surface of the medium; and a part of the fixing plate aerodynamically supporting the recording medium so that it is curved with the same curvature in a direction orthogonal to the track, and emitting the laser beam. An optical recording/reproducing device comprising: a transmitting spherical section; and a drive section that controls the rotation of the recording head in the orthogonal direction using the center of curvature of the spherical section as a rotation axis.