JPS62241139A - Method and apparatus for optical recording and reproducing - Google Patents

Abstract

PURPOSE:To reduce the access time by progressing in zigzag or meandering the light spot along a guide track of light beams so as to improve the line density thereby quickening the data transfer speed. CONSTITUTION:A light deflector 14 deflecting light beams in a direction not coincident with the guide track of the light beams is provided in the light path through which light beams are irradiated. The light spot on the optical disk 1 is progressed in zigzag or meandered by the deflection with a constant period and a constant amplitude of the light beams by the deflector 14 and the movement of the information recording face such as rotation. The components are arranged so that the light spot passes on a pre-group when the light beam deflection angle is constant and a tracking error signal is obtained in this case. The line density is improved substantially in this method to lower the track density thereby reducing the access time.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a recording/reproducing method in an optical memory device such as an optical disk file or an optical data file, which uses optical means when writing and reading information; Regarding the device.

[Summary of the invention]

In the present invention, information is written in an optical disk memory device by making the bit string meander or zigzag on the guide track, rather than by arranging the bits substantially vertically on the track. This paper aims to improve transfer speed and access speed, and also proposes the configuration of a pit position modulation device for this purpose.

[Conventional technology]

Research and development of optical disk memories has been actively conducted for a long time, and image files are already on the market, and commercialization of code data files and the like is imminent. These devices control the position of the spot on the optical disk by forming guide grooves and pre-pits on the disk in advance and obtaining tracking error signals from them. Line up the signal pits in a shape. (The trunk is circular or spiral-shaped, but compared to the size of the pit, it can be considered a straight line.) At this time, the light spot is narrowed down to a diameter of about 1 μm on the disk, so the size of the pit is also about 1 μm. Information can be recorded with extremely high density.

[Problem that the invention seeks to solve]

When the above-mentioned conventional optical disk memory device is viewed as a memory device for code data, it is compared with a magnetic disk device in terms of performance. At this time, record.

Optical disk memory devices have an advantage in terms of density, but magnetic disk devices have an advantage in terms of data transfer rate and access speed. The cause of this is
The problem is that optical heads are heavier than magnetic heads and difficult to access at high speeds, but on top of that, optical disk memories have a lower linear density of information recording and higher track density than magnetic memories. The point is important. For this reason, optical disk memory devices have lower transfer rates and access speeds than magnetic disk devices.

[Means for solving problems]

Therefore, in the present invention, along the guide track of the light beam, the light spot is moved in a zigzag manner or moved so that the line connecting the centers of the light beam has an amplitude of at least the diameter of the light spot or more and a period of about several times that of the light spot. For this purpose, an optical deflector is provided in the optical path for irradiating the light beam to deflect the light beam in a direction that does not overlap the guide track of the light beam.

[Effect]

The light spot on the optical disk travels in a zigzag or meandering manner due to the deflection of the light beam with a constant period and constant amplitude by the optical deflector and the rotation or translation movement of the information recording surface. The tracking error signal can be obtained by arranging the light spot so that it passes over the pregroove or prepit when the deflection angle of the light beam is a constant angle. According to this method, the linear density is substantially improved and the track density is reduced, and the total information recording density remains almost the same.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. 1st
The figure shows an example of how to write information on an optical disc according to the present invention, in which a guide trunk 2 in the form of a remembrance circle is set on an optical disc 1 on a zero disc.

This guide track 2 forms a guide groove or a pre-pit. Normally, the position of the objective lens is controlled based on the detected tracking error signal, but in this embodiment as well, when the light spot falls on this guide track, the tracking error is obtained by the push-pull method as usual. The signal controls the objective lens to be in a constant position relative to the guide track 2.

In the pit row on the right side of FIG. 1, the light spot is vibrated in the radial direction in a triangular wave shape in accordance with the rotation of the disk, and in the pit row on the left side, the light spot is vibrated in a sinusoidal wave shape. At this time, for example, in triangular wave vibration,
If the pit 3 on the guide trunk 2 has a period of IMHz, the radial vibration of the light spot is I
MHz may be used. In the case of sinusoidal vibration, two pits in one period are on the guide trough 2, so that corresponding period is taken into consideration. In the above case, 6 in one cycle
Since it contains a double pit, a 6 MHz signal can be obtained. In this way, the light spot is vibrated at a constant amplitude and at a constant cycle, and the vibration and light emission (during writing) are synchronized depending on the timing when the light spot arrives on the guide trunk 2.
Furthermore, a tracking error signal can be obtained. According to the above method, the notch of the guide trunk is 6 to 7μ.
m, which essentially means lowering the track density and increasing the linear density.

Here, an example of a method of vibrating a light spot with high frequency will be shown below with reference to FIG. The light beam 1) emitted by the semiconductor laser 10 is made into parallel light by a collimator lens 12, passes through a beam splinter 13, and enters an optical deflector 14. Specifically, this optical deflector 14 may be an acousto-optic deflector, an electro-optic deflector, or the like. Here, the light emitted from the optical deflector 14 is vibrated at a high frequency. The deflection angle at this time is, assuming that the focal length of the objective lens 15 is 4°5, and that it is desired to have an amplitude of 9 μm on the disk.
Approximately 0.1 degree is sufficient. Luminous flux 10 reflected by optical disk l
returns to the original optical path, is reflected by the beam brick 13, passes through the detection lens 17, and is sent to the photodetector 18.
incident on . Therefore, no matter how many times the light beam is deflected by the optical deflector 14, the position at which the light beam is incident on the photodetector 18 does not change. This point is superior to the method using a semiconductor laser array currently under consideration. When using a semiconductor laser array as a light source, there is an advantage that multiple trunks can be read simultaneously, but with one optical system, the effective field of view of the collimator lens and objective lens,
Due to the problem of spatial separation of multiple light beams, it is impossible to array the light sources into three or more. On the other hand,
For example, in the case of this embodiment, if there is an amplitude of 9 μm on the disk, it is possible to line up 5 to 6 focal points in the radial direction.

By the way, in the embodiment explained in FIG. 1, if you want to maximize the recording density, as shown in FIG. It is a good idea to record the images even in the areas where there are gaps in focus.

Of course, the spots 7 are symmetrical about the guide track 2.
) may be made to vibrate. In addition to the above-mentioned optical polarizers, galvanic mirrors and holographic polarizers can also be considered, but galvanic mirrors are unlikely to be used for high frequencies.

〔Effect of the invention〕

As described above, the optical recording/reproducing method and apparatus of the present invention actually increase the linear density, thereby increasing the data transfer rate, and actually decreasing the track density, thereby shortening the access time.

[Brief explanation of drawings]

1 and 3 are explanatory diagrams of an embodiment of the present invention, respectively, and FIG. 2 is a configuration diagram showing an optical system of an embodiment of the present invention. l-- Optical disk 2 --- Guide track 3 --- Pit lO --- Semiconductor laser 1) --- Luminous flux 12 --- Collimator lens 13 --- -Beam splitter 14---One optical deflector 15---One objective lens 18-1111...Photodetector Applicant Seiko Electronics Co., Ltd. → Teisla Radical Angle Figure 2

Claims (3)

[Claims] (1) In an optical recording/playback device that performs recording and playback by irradiating a light beam onto a recording medium that moves through rotational or translational motion, light is emitted along the guide track of the light beam during recording and playback. An optical recording/reproducing method characterized in that the spots are zigzag or meandered so that a line connecting their centers has an amplitude at least greater than the diameter of the optical spot and a period several times that of the optical spot. (2) A patent characterized in that a tracking error signal during recording/reproduction is obtained by a signal due to an imbalance of diffracted light obtained when a spot falls on a pre-groove or pre-pit provided in advance on a recording medium. An optical recording/reproducing method according to claim 1. (3) An optical system characterized in that the zigzag progression or meandering of the light spot is performed by an optical deflector that is installed in the optical path for irradiating the light beam and deflects the light beam in a direction that does not coincide with the guide track of the light beam. Recording/playback device.