JPS6378352A - Optical recording medium - Google Patents

Abstract

PURPOSE:To set a tracking line without decreasing the area of a data storage area by providing recessed and projecting parts onto a data recording face alternately, using the recessed and projecting parts as data tracks and using the boundary between the recessed and projecting parts as tracking lines. CONSTITUTION:The titled recording medium is constituted by providing the recessed part 3a and the projecting part 3b alternately in parallel to a recording area 2 provided on the major face of a card type base 1 as the data storage area. The substance information optically is provided as layers to the storage area 2. The recessed part 3a and the projecting part 3b are constituted with a step being 1- several tens microns to the upper face of the storage area 2 and it is preferred to form the boundary E between the recessed part 3a and the projecting part 3b as sharp as possible. The the tracking is attained by radiating a tracking light beam to the boundary E between the recessed part 3a and the projecting part 3b, detecting the luminous quantity change of the reflected light so as to detect the tracking error.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a data recording surface of an optical recording medium with a data track and a tracking line arranged side by side, and writes data on the data track with the tracking line as a reference. This invention relates to an optical recording medium that can be read/written.

[Prior Art] In recent years, optical recording media that record digital data by forming optically variable patterns such as bright and dark bits on the data recording surface have been attracting attention. This optical recording medium can record data at high density in a small area, making it possible to realize a large-capacity memory. Therefore, in addition to disks, card-type memories such as magnetic cards are also being considered.

By the way, in optical recording media, it is necessary to perform accurate positioning when reading and writing data.

Therefore, in order to perform tracking accurately, it has conventionally been common practice to provide a tracking line parallel to the data track. That is, data is written/read while following the tracking line. In this case, the tracking is performed on a band-shaped tracker/'! A tracking light beam is irradiated onto the edge of the +-ng line, and changes in the amount of reflected light based on the relative displacement of the edge are detected.
This is done by detecting tracking errors.

[Problems to be Solved by the Invention] By the way, in the conventional tracking method described above, since a tracking line must be provided on the optical recording medium,
Accordingly, the area for recording data becomes smaller. That is, since one tracking line is provided for one data track, the area of the area in which data can be recorded becomes approximately 1/2 of the area of the entire medium.

This problem does not arise in disc-type optical recording media such as video discs and compact discs, which have a physically large area, so the reduction in recording area caused by providing tracking lines is not a problem.

However, in the case of a card-type optical recording medium, the area that can be used for recording data is narrower than that of the above-mentioned disc-type optical recording medium, so the reduction in the recording area caused by setting the tracking line cannot be ignored.

In particular, when used for applications that require storing a certain amount of data, for example, when creating a dictionary,
It is necessary to use the data recording area effectively. Therefore,
It is undesirable to set the tracking angle in a manner that reduces the area of the data recording area as in the prior art.

The present invention was made to solve such problems,
An object of the present invention is to provide an optical recording medium in which a tracking line can be set without reducing the area of a data recording area, and the amount of data that can be recorded is greatly increased.

[Means for Solving the Problems] As a means for solving the above-mentioned problems, the present invention provides a data recording surface of an optical recording medium so that recesses and projections are arranged alternately in parallel, and the recesses and projections are arranged in parallel. Each convex part is a data track,
Further, the present invention is characterized in that the boundary between the concave portion and the convex portion is used as a tracking line, and data is written in each of the four portions and the convex portion using the tracking line as a reference.

[Function] According to the present invention, data tracks are provided on the four parts and the convex parts that are arranged in parallel alternately, and each data track is positioned by using the boundary line between the concave part and the convex part as a tracking line. Tracking is performed by irradiating a tracking light beam onto the boundary line between the concave portion and the convex portion, detecting a change in the amount of reflected light, and detecting a tracking error.

That is, since there is a difference in level between the concave portion and the convex portion, when focusing the light beam for reading and writing,
Of the light beam irradiated across both the concave portion and the convex portion, the reflected light from the side that is in the focal plane becomes stronger. the result,
A state similar to that obtained when the edge of the conventional belt-shaped tracking line is irradiated with a light beam is obtained.

Therefore, according to the present invention, by using the boundary between the concave portion and the convex portion as a tracking line, tracking can be performed in the same manner as in the above-mentioned conventional tracking method using the edge of a belt-like tracking line.

[Example] Embodiments of the present invention will be described with reference to the drawings.

<Configuration of the Embodiment> FIG. 1 shows the appearance of an embodiment of the optical recording medium of the present invention, and FIG. 2 shows an enlarged view of the main parts thereof.

As shown in FIG. 1, the optical recording medium of this embodiment has concave portions 3a and convex portions 3b alternately arranged in parallel as data recording areas in a recording area 2 provided on the main surface of a card-type substrate l. It consists of

The card board 1 is made of plastic or the like, and has the same shape and size as a magnetic card or the like.

The recording area 2 is provided with a layered material capable of optically recording information. For example, when irradiated with a light beam such as a laser beam, the material may be locally melted and the reflectance may be reduced.
The recording area 2 is formed by covering the recording area 2 in a layered manner with a material that has the property of locally turning black and decreasing the reflectance. Also,
This recording area 2 is provided with four parts 3a and a convex part 3b as a data recording area.

These concave portions 3a and convex portions 3b are formed on the upper surface of the recording area 2. It is configured with a step difference of about several tens of microns. This unevenness can be easily formed using, for example, photolithography technology. In this case, it is preferable that the boundary E between the concave portion 3a and the convex portion 3b be formed as sharply as possible.

The concave portion 3a and the convex portion 3b each serve as a data recording area. That is, data is written by forming bit 5 as shown in FIG.

<Operations of the Embodiments> Next, the operations in data writing/reading of the optical recording medium configured as described above will be described above.

This will be explained with reference to each figure and FIGS. 3 and 4.

In this embodiment, when reading and writing data on one data track, three light beams B1. Use B2 and B3. These light beams B1. B2 and B3 are arranged so that the light spots each formed on the recording area 2 are centered on the beam B2, and the light spots of the beams Bl and B3 are located at the boundary E between the concave portion 3a and the convex portion 3b. It is set.

These light beams B1. B2 and B3 are formed by the optical system shown in FIG. That is, this optical system includes a light source 6 such as a semiconductor laser, a collimating lens 7 that converts the light emitted from the light source 6 into parallel light, and a plurality of light beams (
In this embodiment, there is a diffraction grating 8 that divides the beam into three beams, a beam splitter 9 that separates the transmitted light and the reflected light, and a quarter beam splitter that makes the polarization planes of the incident light and the reflected light orthogonal to each optical recording medium. a one-wavelength plate 10, an objective lens 11, and an eyepiece 1 that images reflected light from the optical recording medium 1 onto a photoelectric detector P.
2, a splitter 13 that separates a portion of the light beam to the eyepiece 12, and an autofocus device 14 that performs focusing using the split light beam.

The photoelectric detector P is composed of, for example, three PIN photodiodes formed on the same substrate, and includes a reading P2 and tracking PI and P3 arranged on both sides thereof. The reading photoelectric detector P2 is connected to a reading circuit (not shown). Tracking photoelectric detector P1. The output of P3 is connected to a differential amplifier (not shown), and the difference in light amount between the two is detected. In addition to this, the autofocus device 4 includes a focusing detector (not shown).

The above optical system can be used for both writing and reading. During writing, by increasing the output energy of the light source 6, the irradiated part of the light beam B2 is physically or chemically changed to cause an optical change, and data is written.On the other hand, data is written. In this case, the output energy is reduced to form a light spot without physically or chemically changing the irradiated part of the light beam B2, and to remove the optical change that was previously formed in the irradiated part. Let be the information of the reflected light.

Note that the intensities of B1 and B3 with respect to light beam B2 are:
Since it is less than 1/1O, physical or chemical changes in the portion irradiated by the light beams B1 and B3 can be ignored even during writing.

When writing data to the convex portion 3b of the optical recording medium of this embodiment using the optical system described above, first, the light beam B2 is focused on the surface of the convex portion 3b by the autofocus device 14. As shown by Hl in FIG. 4, the light beams B1 and B3 irradiated onto the boundary E are focused on the surface of the convex portion 3b with respect to the light beam B2, so that the light spots they form are closer to the inner side (inner side). 4, indicated by diagonal lines) has high brightness, while the outer side has low brightness because it illuminates the concave portion 3a where the focus is not aligned.

This high brightness portion is the photoelectric detector P1. Each is detected at P3. If there is a difference between the two outputs, it is detected that there is a tracking error, and based on this tracking error signal, the optical head is relatively displaced in the width direction of the convex portion 3b by a servo control system (not shown). and correct the tracking error.

As a result, the center of the light beam B2 is located at the center of the convex portion 3b where data is to be written, and data is written in the data track b.

Next, when injecting data into the recess 3a of the optical recording medium of this embodiment, the light beam B2 is first focused on the surface of the recess 3a by the autofocus device 14. Fourth
As shown by B2 in the figure, the light beams B1 and B3 irradiated onto the boundary E are focused on the concave portion 3a surface where the inner side of the light spot they form (indicated by diagonal lines in FIG. 4) is focused. The brightness is high because it is illuminating the area, and the brightness is low because the outside side is illuminating the convex portion 3b whose focus is not aligned.

This high-luminance part is connected to the photoelectric detector P1 in the same manner as above.
．． P3 is detected and the tracking error is corrected in the same manner as above.

The above is the operation when writing data, but it is exactly the same when defoaming data.

As described above, in this embodiment, a light beam is irradiated onto the boundary E between the concave portion 3a and the convex portion 3b, and a high-intensity portion appearing at the boundary E is formed within the light spot formed by the beam. The tracking error can be detected from the difference in the light amount of the high-brightness portion between the two boundary portions E sandwiching the target data track Dt. Therefore, in this example,
The boundary E becomes a tracking line and acts in the same way as the edge of a conventional belt-like tracking line.

[Effects of the Invention] As described above, the present invention has the effect of being able to set tracking lines without reducing the area of the data recording area, and greatly increasing the amount of data that can be recorded.

Therefore, according to the present invention, in a card-type recording medium with a limited area, it is difficult to use the same tracking method as in the conventional disk-type recording medium. It enables the recording of large amounts of data and facilitates the realization of dictionaries, etc.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the external appearance of an embodiment of the optical recording medium of the present invention, FIG. 2 is an enlarged perspective view of the main part, and FIG.
Fig. f/S3 is an optical path diagram showing an example of the optical system used for reading and writing in this embodiment, and Fig. 4 is an explanatory diagram for explaining the operation of this embodiment. l... Card type substrate 2... Recording area 3... Data recording area 3a... Concave portion 3b... Convex portion 5... Bit 6... Light source 7... Collimating lens 8... - Diffraction grating 9... Beam splitter 10... Quarter wavelength plate 11... Objective lens 12... Eyepiece lens 13... Brancher 14... Autofocus device B1, B2, B3. ...Light beam Dt...Data track E...Edge P (P+, B2, B3)...Photoelectric detector Applicant Computer Service Co., Ltd. Agent Patent attorney Iwao Mishina Figure 1 Figure 2

Claims (1)

[Claims] The data recording surface of the optical recording medium is provided with concave portions and convex portions arranged side by side alternately, each of the concave portions and the convex portions being a data track, and the boundary between the concave portions and the convex portions being a tracking line. An optical recording medium characterized in that data is written in each of the concave portions and convex portions using the tracking line as a reference.