JP2885325B2 - Optical information reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for reproducing information from an optical recording medium on which information has been recorded in a number of pits arranged in rows.

[0002]

2. Description of the Related Art FIG. 2 shows how information is reproduced in a conventional device of this type. In the drawing, reference numeral 1 denotes an optical recording medium;
For example, the optical disk 2 is an optical head. Optical disk 1
As shown in FIG. 3, a large number of pits 3 representing recording information are formed on concentric or spiral tracks on the recording surface 1a. The optical disk 1 is rotated at a constant rotation speed by a drive system (not shown). The optical head 2 includes a laser, an objective lens, a light receiving element, and the like (all not shown).
And a light beam 4 with respect to the recording surface 1a of the optical disc 1.
And receives the reflected light. At this time, as shown in FIG. 3, the size of the spot 4a of the light beam 4 is limited to about twice the minimum diameter of the pit 3 because it is necessary to narrow the size of the spot 4a so that the ON / OFF of the pit 3 can be sufficiently determined. Therefore, the light beam 4 is narrowed down to the limit by the objective lens. The amount of the reflected light changes depending on the shape of the pit 3, and information is reproduced from the light. The optical head 2 is moved in the radial direction of the optical disk 1 by a driving system (not shown),
Or it is moved in six directions to access a desired track.

[0003]

However, in the above-described apparatus, there is a problem in that the access speed is low due to the large weight of the optical head and the small track pitch of the optical disk. Further, since the size of the pit is determined by the wavelength of the laser used in the optical head, it has not been possible to increase the access speed by making the track smaller as in the case of the magnetic disk drive. In the past, the access speed was improved by using techniques such as reducing the weight of the optical head and optimizing the servo method.However, a lens that essentially narrows the laser down to the size of a pit was used. Due to the limitation of the NA value, high-speed access like a magnetic head was impossible. Recently, a multi-beam system in which the apparent transfer speed is improved by simultaneously irradiating a plurality of light beams has been put into practical use. This has resulted in a decline.

An object of the present invention is to provide an optical information reproducing apparatus capable of realizing high-speed access and high-speed transfer in view of the above-mentioned conventional problems.

[0005]

In order to achieve the above object, the present invention irradiates an optical recording medium on which information is recorded with a large number of pits arranged in a row with light, and reproduces information from the reflected light. An optical information reproducing apparatus that irradiates light onto a range including a plurality of tracks and a plurality of pits on a medium and captures reflected light as a real image; and processes an image captured by the optical head. And an image processing means for extracting a signal corresponding to a pit on at least one track.

[0006]

According to the present invention, an image in a range including a plurality of tracks and a plurality of pits on an optical recording medium is captured by an optical head, and from this image, image processing means converts the image into pits on at least one track. The corresponding signal is picked up, from which the information is reproduced.

[0007]

FIG. 1 shows an embodiment of an optical information reproducing apparatus according to the present invention. In the figure, the same components as those of the conventional example are denoted by the same reference numerals. That is, 1 is an optical disk, 7 is an optical head, 8
Denotes an image processing unit, and 9 denotes a signal processing circuit unit.

The optical head 7 includes a light emitting element, an objective lens, an image pickup element, etc. (all not shown), irradiates the recording surface 1a of the optical disk 1 with a light beam 10, and detects the reflected light as a real image. . Here, the size of the spot of the light beam 10 corresponds to a range including a plurality of tracks and a plurality of pits on the recording surface 1a of the optical disc 1, for example, a circular range 10a shown in FIG. Corresponding images are continuously captured. The optical head 7 is moved in the radial direction of the optical disk 1 by a drive system (not shown), similarly to the conventional optical head.

The image processing unit 8 processes the image obtained from the optical head 7, and extracts a signal corresponding to a pit on a predetermined track by, for example, obtaining a correlation between images taken continuously. The signal processing circuit section 9 reproduces information recorded on a predetermined track of the optical disc 1 from the extracted signal.

According to the above configuration, the range that can be captured by the optical head 7 at one time includes a plurality of tracks, and the allowable range of the positional deviation with respect to one track is large.
A desired track can be accessed at high speed, and the information transfer speed can be improved. Also,
Since it is not necessary to narrow the light beam as in the related art, it is possible to use an LED which is very inexpensive and can easily shorten the wavelength as compared with a laser as the light emitting element of the optical head 7.

The transfer rate of information can be further improved by taking out a plurality of signals corresponding to pits on a plurality of tracks by the image processing section 8 and sending them to the signal processing circuit section 9 at the same time. Further, the optical head 7 may be provided with no image pickup device, and the image may be directly sent to the image processing unit 8 by an optical fiber or the like.

[0012]

As described above, according to the present invention, the range which can be taken in at once by the optical head includes a plurality of tracks, and the allowable range of positional deviation with respect to one track is large. There is an advantage that the desired track can be accessed at high speed, and the transfer speed of information can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of an optical information reproducing apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing how information is reproduced in a conventional optical information reproducing apparatus.

FIG. 3 is a partially enlarged view of a recording surface of an optical disk.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical disk, 7 ... Optical head, 8 ... Image processing part, 10
... light beam, 10a ... range.

Claims (1)

(57) [Claims] An optical information reproducing apparatus for irradiating an optical recording medium on which information is recorded with a large number of pits arranged in a row with light and reproducing the information from the reflected light, comprising: a plurality of tracks on the medium; An optical head for irradiating light to a range including a plurality of pits and capturing the reflected light as a real image; and processing an image captured by the optical head to extract a signal corresponding to a pit on at least one track An optical information reproducing apparatus comprising an image processing means.