JPH01256040A - Optical recording medium and method and device for producing said medium - Google Patents

Abstract

PURPOSE:To enable easy reproduction and good tracking by forming guide tracking lines by a light beam. CONSTITUTION:The guide tracking lines of the optical recording medium having the guide tracking lines on both sides adjacently to the linear regions for recording information signals by irradiation of the focused light beam so as to sandwich said regions are formed by the focused light beam. Namely, while the tracking lines have nearly the same reflectivity as the reflectivity of the recorded information signal pits when locally viewed, the signal pits are generally shorter than the tracking lines and the linear regions where the recording signal pits exist are observed as the average reflectivity. The increase in the tracking sensitivity is, therefore, expected by recording both the recording regions and the tracking lines by the focused light beams. The normal tracking is thereby executed even if a reproducing device designed to allow the points of the high reflectivity to be irradiated by the light beam is used.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to an optical recording medium that performs recording and reproduction (here, recording and reproduction means recording or reproduction, or both) by irradiation with light, and a method for manufacturing the same. and devices. More specifically, the present invention relates to an optical recording medium with good tracking performance during recording and reproduction.

[Prior Art] In optical recording media, recording and reproduction are usually performed by scanning a light beam along a guide track. Here, the guide tracks are provided on the optical recording medium as continuous or discontinuous linear portions having different reflectances, and are usually provided in the form of groups (concave portions).

[Problems to be Solved by the Invention] Tracking is very important in optical recording media, and various proposals have been made to improve tracking performance. However, optical recording media that perform tracking by utilizing the difference in reflectance between a striped area where a signal is recorded (hereinafter referred to as a recording area) and the areas that sandwich it have the following problems. It was.

For example, in an optical recording medium in which the reflectance of the recording area increases upon recording (hereinafter referred to as reflectance increasing type),
Recording the information signal increases the reflectance of the recording area. Therefore, when such a recorded optical recording medium is played back using a playback device designed to irradiate a light beam to a location with low reflectance, the polarity of the signal for track detection may be reversed. . In this case, the reproduction light beam tracks to avoid the recorded signal pits, making normal tracking impossible. Also,
Since the reflectance of the recording area is observed as an average value when the beam moves on the track, recording the signal inevitably lowers the track detection sensitivity.

Similarly, a similar problem occurs when a reproducing device designed to irradiate a light beam to a location with high reflectance using a reduced-reflectance type optical recording medium performs reproduction.

A first object of the present invention is to solve the above-mentioned problems. Other objects of the present invention will become clear from the following description.

[Means for Solving the Problems] The present invention has a striped area for recording and/or recorded information signals by irradiating a focused light beam, and has stripes on both sides sandwiching the area adjacently. An optical recording medium having a guide tracking line on the guide tracking line.
An optical recording medium characterized in that a line is formed by a focused light beam, a method for manufacturing the same, and an apparatus.

The optical recording medium of the present invention is used as a writable optical recording medium. The optical recording medium includes all optical recording media in which the recording area can be recorded as a change in reflectance by forming arbitrary signal pits such as phase change, hole formation, bubble formation, and unevenness formation by irradiation with energy such as light. include. Its shape can also be arbitrary, such as a disk shape or a card shape.

The present invention is characterized in that it is particularly effective for optical recording media of increased reflectance type.

In the present invention, the guide tracking line can also serve as a clock signal. If it also serves as the clock signal, it can be easily set by providing the tracking lines intermittently at desired intervals.

Applications of the invention include, for example, means for irradiating a focused light beam for recording an information signal and for providing a guiding tracking line in the area where the information signal is recorded and/or to be recorded. This is achieved by using an optical recording device characterized in that it is provided with means for irradiating a focused light beam emitted in a pulsed manner on both or one of both sides so as to be adjacent to and sandwiched therebetween. Here, it is easily understood that by using a write once optical recording medium having a normal guide track and writing both the information and the guide tracking line at the same time, it can be reproduced well by a commercially available reproduction device. .

Here, each of the above-mentioned means may be a means that can be easily designed by a person skilled in the art.

[Operation] The tracking line in the present invention is, so to speak, written by irradiation with a focused light beam.

The tracking line therefore has approximately the same reflectance locally as the recorded information signal pit. on the other hand,
In general, signal pits are shorter than tracking lines, and there are sufficient unrecorded areas between the pits, and the striped areas where recorded signal pits exist are observed as average reflectance. Ru. Therefore, it is expected that tracking sensitivity will be improved by recording both the recording area and the tracking line with a focused light beam.

More specifically, for example, in a reflectance-increasing optical recording medium, the effect is as follows.

Recording an information signal in the recording area increases the reflectance, but at the same time, the tracking lines formed to sandwich the area are similarly formed by a focused light beam, so the reflectance of the tracking lines also increases. increases, and the average reflectance of the tracking line can be set higher than the average reflectance of the recording area. Therefore, normal tracking can be performed even when using a reproducing device designed to irradiate a light beam to a location with low reflectance. Similarly, in a reflectance-reducing optical recording medium, the reflectance is reduced by recording a signal in a recording area, or at the same time, tracking lines formed to sandwich the area are similarly focused on a light beam 1. The tracking and
The line also has reduced reflectance. Therefore, normal tracking can be performed even when using a reproducing device designed to irradiate a light beam to a location with high reflectance.

[Example] The present invention will be explained in more detail below based on examples.

Example 1 A thin metal film made of platinum was applied by sputter deposition so that the reflectance was about 10% on a plastic substrate having spiral grooves with a depth of about 70 nm, a pitch of 3 μm, and a groove width of 0.7 μm. did. A test signal with a duty ratio of 50% was recorded on the groove portion while tracking using a push-pull method. Next, when I played back the image using a three-beam system that tracks the side where the amount of reflected light decreases, tracking was impossible.

Next, this disk was irradiated with a laser beam having a spot diameter of 0.83 μm defined by the half-value width along the land portion of the groove. Next, when I played it back using the same three-beam playback device as above, tracking became possible.

When the surface of the disk was observed using a scanning electron microscope (SEM), it was found that bubble-shaped tracking lines were formed in the land portions. The reflectance of this land portion was 40%, which is approximately the same as the reflectance of the information signal portion.

Example 2 Using the same plastic substrate as in Example 1, Te.

A film made of carbon and hydrogen and having a reflectance of 30% was formed to obtain an optical disc. A test signal with a duty ratio of 50% was recorded in the groove part of this disc while tracking using the push-pull method, and when it was played back using a three-beam playback device that tracks the parts with high reflectance, tracking was impossible. .

Next, this disk was irradiated with a laser beam having a spot diameter of 0.83 μm defined by the half-value width along the land portion of the groove. Next, when I played it back using the same three-beam playback device as above, tracking became possible.

[Effects of the Invention] As is clear from the above explanation, according to the present invention, there is provided a recordable write-once optical recording medium that can be easily reproduced even when reproduction after recording is difficult. provided. Similarly, the optical recording medium of the present invention can perform good tracking even when tracking is performed simultaneously with writing.

Claims (1)

[Scope of Claims] 1) There is a striped area for recording and/or recorded information signals by irradiating a focused light beam, and guide tracking and tracking are provided on both sides of the area adjacently sandwiching the area. 1. An optical recording medium having a line, the guiding tracking line being formed by a light beam. 2) recording information signals by irradiating a focused light beam and/or providing a guiding tracking line by irradiating focused light beams on both sides adjacent to and sandwiching the recorded striped region; A method for manufacturing an optical recording medium characterized by the following. 3) means for projecting a focused beam of light for recording an information signal, and for providing a guiding tracking line sandwiching adjacent to the area in which said information signal is and/or will be recorded; An optical recording device characterized by comprising means for irradiating a focused light beam on both sides. 4) means for projecting a focused light beam for recording an information signal and a focused light beam adjacent to the area in which said information signal is or will be recorded for providing a guiding tracking line; An optical recording device characterized in that it is provided with means for irradiating.