JP2885326B2 - 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]

According to the present invention, in order to achieve the above object, a first aspect of the present invention is to irradiate light on an optical recording medium on which information is recorded by a large number of pits arranged in a row and reflect the light. In an optical information reproducing apparatus for reproducing information from light,
An optical head for irradiating light to all tracks on the medium and capturing the reflected light as a real image; and an optical head for processing an image captured by the optical head and corresponding to pits on all tracks on the medium, respectively. An optical information reproducing apparatus comprising: an image processing means for extracting a signal of (i), and a switch means for extracting a signal corresponding to a pit on at least one desired track from the large number of signals. A plurality of light detectors for irradiating light to a range including a plurality of tracks and a plurality of pits and capturing the reflected light as a real image, each capturing range being substantially linear over a length corresponding to all tracks of the medium. An optical information reproducing apparatus according to claim 1, wherein an optical head is provided so as to be disposed in the optical information reproducing apparatus.

[0006]

According to the first aspect of the present invention, an image over all tracks on an optical recording medium is captured by an optical head, and a plurality of images corresponding to pits on all tracks on the medium are read from this image by image processing means. And a signal corresponding to a pit on at least one desired track is extracted from the large number of signals by the switch means, and information is reproduced from the extracted signal.

According to a second aspect of the present invention, a plurality of photodetectors are provided so that each capture range of the optical head is arranged substantially linearly over a length corresponding to all tracks of the optical recording medium. More light is radiated, and the reflected light is captured as a real image, whereby an image over all tracks on the medium is captured, and thereafter, the same processing as described above is performed.

[0008]

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, 10 is an optical head,
Reference numeral 20 denotes an image processing unit, 21 denotes a switch unit, and 22 denotes a signal processing circuit unit.

The optical head 10 has a large number, in this case, fourteen photodetectors 11. The light detection unit 11 is a light emitting element,
Equipped with an objective lens, an image sensor, etc.
The recording surface 1a of the optical disk 1 is irradiated with a light beam 12, and the reflected light is detected as a real image. Here, the size of the spot of the light beam 12 is the recording surface 1a of the optical disc 1.
It corresponds to a range including a plurality of tracks and a plurality of pits, for example, a circular range 12a shown in FIG. 3, and images corresponding to the range 12a are continuously captured. Also,
As shown in FIG. 4, each light detection unit 11 is provided with each capture area 12a.
Are mounted on a support member, for example, an arm 13 so as to be arranged substantially linearly over a length corresponding to all tracks of the optical disc 1. Also, as described above, the light detection unit 11
Has an objective lens, which is larger than the size of the spot of the light beam 12, so that the respective photodetectors 11 are mounted alternately. As shown in FIG. 5, the optical head 10 is fixedly arranged along its radial direction so that a light beam bundle 14 composed of a set of light beams 12 from each light detector 11 crosses all tracks of the optical disk 1. You.

The image processing unit 20 processes the images obtained from the respective light detectors 11 of the optical head 10, for example, by taking a correlation between the images continuously captured by the respective light detectors 11, etc. A large number of signals corresponding to pits on all tracks of one are extracted. The switch unit 21 extracts a signal corresponding to a pit on a predetermined track separately designated from the plurality of signals. The signal processing circuit section 22 reproduces information recorded on a predetermined track of the optical disc 1 from the extracted signal.

According to the above configuration, the optical head 10
An image over all the tracks of the optical disk 1 can be captured without moving it, and from this image, a large number of signals corresponding to pits on all the tracks of the optical disk 1 can be extracted by the image processing section 20. Thus, a signal for a pit on an arbitrary track can be extracted by the switch unit 21. Therefore, a desired track can be accessed at a very high speed, and the information can be transferred at a high speed. In addition, since each light detector 11 of the optical head 10 does not need to narrow the light beam as in the conventional case, it is necessary to use an LED which is very inexpensive and can easily shorten the wavelength as compared with a laser as its light emitting element. it can.

It should be noted that a plurality of signals corresponding to pits on a plurality of tracks are extracted from a large number of signals extracted by the image processing section 20 and are simultaneously sent to the signal processing circuit section 22, thereby increasing the information transfer speed. It can be further improved. Further, each light detection unit 11 of the optical head 10 is not provided with an image sensor, and an image is processed by an image processing unit 2 using an optical fiber or the like.
It may be sent to 0 as it is. Optical head 1
At 0, the number of the light detection units 11 can be reduced by attaching the light detection units 11 to a displacement element such as a piezo and performing swiveling scanning. In the above embodiment, only one optical head 10 is arranged on the optical disk 1, but a plurality of optical heads may be arranged.

[0013]

As described above, according to the first aspect of the present invention, an image over the entire track of the optical recording medium is captured without moving the optical head by the optical head, and the optical recording medium is read from the image by the image processing means. A large number of signals corresponding to the pits on all tracks of each of the tracks, and a signal for a pit on an arbitrary track can be extracted from the large number of signals by the switch means. Access can be made at high speed, and the information can be transferred at high speed.

According to the second aspect of the present invention, since each light detecting section of the optical head does not need to narrow down the light beam as in the prior art, its light emitting element is very inexpensive as compared with a laser, and An LED whose wavelength can be easily reduced can be used.

[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.

FIG. 4 is a plan view of an optical head.

FIG. 5 is an explanatory diagram showing an arrangement of an optical head with respect to an optical disk;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical disk, 10 ... Optical head, 11 ... Light detection part, 1
2: light beam, 12a: range, 20: image processing unit, 21
... Switch section.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G11B 7/00 G11B 7/135

Claims (2)

(57) [Claims] 1. An optical information reproducing apparatus which 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, for all tracks on the medium. An optical head that irradiates light and then reflects the reflected light as a real image, and an image processing means that processes an image captured by the optical head to extract a number of signals corresponding to pits on all tracks of the medium, respectively. An optical information reproducing apparatus, comprising: a switch for extracting a signal corresponding to a pit on at least one desired track from the plurality of signals. 2. A plurality of light detectors for irradiating light to a range including a plurality of tracks and a plurality of pits on a medium and capturing the reflected light as a real image, each capture range corresponding to all tracks of the medium. 2. The optical information reproducing apparatus according to claim 1, wherein an optical head provided so as to be arranged substantially linearly over the length is used.