JPH0676350A - Optical informaito recording and reproducing device - Google Patents

Abstract

PURPOSE:To provide an optical information recording and reproducing device in which the processing time for an information reproduction is reduced and the reproduction speed is made faster. CONSTITUTION:Against a recording medium, which has plural tracks 273 in that an information is recorded, a reproduction light beam 30 is irradiated so that it is spread over the plural tracks 273. The device has an optical head which simultaneously produces the information of plural tracks 273, that is irradiated by the reproduction beam 30, by plural reproduction light receiving elements 341. Let + or -G be the motor error of the movement of the optical head which is moved to a prescribed track 273 and set the number of plural reproduction light receiving elements 341 to be N where N>=2G+1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus for recording / reproducing information using a recording medium such as an optical card.

[0002]

2. Description of the Related Art Recent technological advances in information processing have been remarkable, and along with this, means for recording information in an ever-increasing capacity have been considered. One of them is an optical information recording / reproducing device. Is attracting attention.

In such an optical information recording / reproducing apparatus, an optical card is used as a recording medium, and an optical card apparatus for recording / reproducing information on / from this optical card has been put into practical use.

Here, the optical card is one in which data is written by irradiating the information recording layer with laser light focused by a lens to form pits (holes) in the recording layer due to thermal irreversible change. Therefore, it has a recording capacity several thousand times to 10,000 times larger than that of a magnetic card used conventionally. Although it is not possible to rewrite data like optical discs, it has a very large storage capacity of 1 to 2 Mbytes, so that it can be used in a wide range of applications such as bank savings passbooks, mobile maps, and prepaid cards used for shopping. Also, by utilizing the characteristic that data cannot be rewritten, application to an application that does not allow tampering of data such as a personal health care card is also considered.

FIG. 6 shows an example of an optical card, which has a data recording section 2 at the center of the card body 1 and ID sections on both sides of which the data such as track addresses are recorded. It is configured to have 3a and 3b.

In this case, as shown in FIG. 7, the data recording section 2 includes a plurality of track guides 201 for guiding a light beam of laser light in the track direction, and tracks formed between these guide tracks 201. 202, and data pits 203 representing recording information are formed along these tracks 202.
Information is recorded / reproduced on such an optical card by the optical system of the optical head shown in FIG.

In this case, the laser light emitted from the light emitting element 4 is shaped into parallel light by the collimator lens 5, diffracted light is taken by the diffraction grating 6, and focused on the optical card 1 through the objective lens 7. I will tie it. Then, the focused light is reflected by the optical card 1, passes through the mirror 8 and the detection system lens 9, and enters the detector 10.

Here, the light beam at the focal point on the optical card 1 is, as shown in FIG. 7, a beam 601 called a main beam and beams 602 and 603 called sub-beams, which are diffracted by the diffraction grating 6. The beam 601 is used to generate a focus error signal for recording / reproducing or focusing control of the data pit 203, and the beams 602 and 603 are used for the track guide 201.
It is arranged so that it will take half each of them and is used to generate a track error signal.

The detector 10 which is reflected from the optical card 1
The light beam incident on is obtained as shown in FIG.
Here, the light beams 101, 102 and 103 correspond to the light beams 601, 602 and 603 of FIG. In the detector 10, the light beam 101 is divided into two detection regions 10
The light beam 102 is located at the center of the detection area 102a and the light beam 103 is located on the detection line 103 on the dividing lines 1a and 101b.
When the beams on the optical card 1 are deviated from the focused state such that they are located at the center of each a, the light beam 101 moves in a direction orthogonal to the dividing line of the detection regions 101a and 101b. By obtaining the difference between the positional shifts of 101a and 101b, a focus error signal indicating the shift of the in-focus position is obtained, and based on this focus error signal, the objective lens 7 is moved closer to or farther from the card by the objective lens driving means 11. Thus, the focusing control is performed to maintain the in-focus state. Also, the beams 602 and 603 shown in FIG.
When moving in a direction orthogonal to, the degree of engagement of the track guide 201 with respect to each of the beams 602 and 603 changes. Therefore, the difference between the detection regions 102a and 103a causes the beam to deviate from the center of the track guide 201. To obtain the track error signal
Based on this track error signal, the objective lens 7 is driven by the objective lens driving means 11 in the direction perpendicular to the track guide 201, so that the beam 601 is moved to the track 2
02 Tracking control for keeping the center is performed. Next, FIG. 10 is for explaining a method of accessing an arbitrary track adopted in the optical information recording / reproducing apparatus having such a configuration.

In this case, in the same manner as described with reference to FIG.
Reference numeral 01 is a track guide for guiding the light beam of the laser light in the track direction, and 202 is these track guides 20.
1, 601 indicates a track formed between the tracks 1, 601 is a main beam for reproducing data pits formed along the track 202, and 602 and 603 are track guides 201.
Each of the sub-beams is arranged so as to occupy half of each of them and generates a track error signal. Further, here, both ends of the track 202 indicate both ends of the card, and the arrow in the drawing indicates the moving direction of the beam on the card. Generally, the movement of the beam on the card is performed by moving the optical head itself or the objective lens in the direction perpendicular to the figure, and moving the card with respect to the optical head in the horizontal direction. Done in. In this state, a host computer (not shown) gives an instruction to reproduce data at a certain track address.

In the figure, assuming that the track address is AD1, the beam is moved in the direction of arrow a in the figure by the difference between the track address AD currently located and the track address AD1 to be moved.

By the way, usually, since the distance in the direction of the arrow a for moving the beam to the instructed movement target address is large, it is dealt with by moving the entire optical head. In this case, the beam position after movement is within a certain error range with the target track as the center, and it is not always possible to turn on the target track once.
Generally, such access for moving the entire optical head is called coarse access. Here, possible causes of the error due to the rough access include insufficient precision of the scale used for the rough access, vibration of the objective lens, vibration of the apparatus itself, and the like.

In the example of FIG. 10, it is assumed that the beams 601, 602, and 603 are moved three tracks before the target track address AD1 due to a rough access error. And by moving the card side in this state,
When the beams 601, 602, and 603 are relatively moved in the direction of the arrow b in the figure, at this time, the above-mentioned ID portion 3a of the card is reproduced so that the track address of this track is A.
Since it is found to be D0, the difference between the track address AD0 and the target track address AD1 causes the beams 601, 602 and 603 to move again by a distance corresponding thereto. In this case, since the moving distance is short (about 1 to 8 tracks at most), the beam is usually moved by the objective lens one track at a time. This is called a trunk jump, and precise movement of a small distance by repeating such a trunk jump is called dense access.

In FIG. 10, the track 202 is reached at the target track address AD1 by repeating the track jump three times as shown by arrows c1, c2 and c3. And in this state, move the card side,
When the beams 601, 602, 603 are relatively moved in the direction of the arrow d in the figure, at this time, the above-mentioned ID portion 3b of the card is reproduced so that the track address of this track is A
It is confirmed that the data is D1 and the data is reproduced.

In this way, when the absolute value of the difference between the currently located track address and the target track address is larger than a predetermined value, the access can be performed by repeating the rough access and the fine access. Will be done.

[0016]

When the moving distance from the currently located track address to the target track address is large as described above, it is difficult to access the target track at one time, and rough access is required. Since the processing by the dense access is performed, the track scanning is required at least twice in the normal access, and as a result, it takes a lot of time to reproduce the data and the reproduction speed cannot be made too high. It was

The present invention has been made in view of the above circumstances. It is possible to quickly access a target track, shorten the processing time for information reproduction, and increase the reproduction speed. It is an object of the present invention to provide an optical information recording / reproducing device that can be used.

[0018]

According to the present invention, there is provided a means for generating a reproducing light beam for simultaneously irradiating a plurality of tracks onto a recording medium having a plurality of tracks on which information is recorded, and a means for irradiating the reproducing light beam. An optical head having a plurality of light receiving elements for simultaneously detecting information on a plurality of tracks,
When the movement error when moving the optical head to the target track is ± G, the number N of the plurality of light receiving elements is N.
Is set to N ≧ 2G + 1.

[0019]

As a result, according to the present invention, the number of the plurality of light receiving means for simultaneously detecting the information of the plurality of tracks of the recording medium irradiated with the reproducing light beam is determined by the above equation according to the movement error ± G. By doing so, even if the moving distance to the target track address is large, the data of the target track can be reproduced by one scanning. As a result, the processing by the dense access can be omitted, the track scanning can be performed once, the processing time of the data reproduction can be shortened, and the reproduction speed can be increased.

[0020]

First, the concept of the present invention will be described.

FIG. 1 shows a relationship between an access error at the time of rough access in a general optical information recording / reproducing apparatus and its occurrence frequency. In this case, as is apparent from the figure, the distribution of the access error occurrence frequency is the largest in the vicinity of the access error of zero, sharply decreases as the access error increases, and rarely occurs beyond a certain range. In the figure, the range in which this access error disappears is indicated by G (± 4).

Therefore, in the present invention, a plurality of reproducing light receiving elements are prepared for the reproducing light beam, and a multi-track read is adopted in which a plurality of tracks can be read at a time by the plurality of reproducing light receiving elements. By setting the number N of these reproducing light receiving elements (the number of tracks that can be reproduced at one time) to ± G which is the range of the error that occurs in the rough access, N ≧ 2G + 1, the error in the rough access is ± G. Within the range, the target track can be reproduced by one scan after rough access. An embodiment of the present invention based on this concept will be described below with reference to the drawings. Figure 2
3 shows a schematic configuration of an optical system of an optical head of the optical information recording / reproducing apparatus of the embodiment. In the embodiment, as shown in FIG. 1, G = ± 4, and N = 9 from the above equation, that is, nine reproducing light-receiving elements are prepared for the reproducing light beam. .

In this case, the recording light beam generated by the semiconductor laser 21 is formed into a substantially elliptical parallel beam by the collimator lens 22. Then, this parallel beam is given to the shaping prism 23 to be shaped into a substantially circular shape in which only the major axis direction of the ellipse is reduced, and is further narrowed down by the circular diaphragm 24 so that the spot size of the recording light beam becomes a predetermined value. I have to.

Due to the property of the semiconductor laser 21, this circular beam is composed of almost S-deflection component, is almost reflected by the reflection surface of the deflection beam splitter 25, and is incident on the optical axis of the objective lens 26. This light is condensed on the optical card 27 by the objective lens 26 and becomes a circular light spot 271 as shown in FIG. Then, the energy density is locally increased by the light spots 271, and the data pits are formed by causing a thermal irreversible change in the recording layer of the optical card 27.

Here, the optical card 27 has a plurality of track guides 272 and a track 273 formed between these track guides 272 as shown in FIG. 3, and is modulated with information to be recorded. When a pulse is applied to the semiconductor laser 21 to emit light in a pulsed manner, data pits 274 are sequentially generated along the track 273 by the light spot 271 corresponding thereto, and information is recorded as a pit train.

On the other hand, the reproduction light uses, for example, a light emitting diode 28 such as an end face light emitting diode having a slit-shaped light emitting surface as a light source, a collimator lens 29 converts the light into substantially parallel light, and a deflection beam splitter 25 causes a P deflection component. Only the light is transmitted, enters through the objective lens 26 at a position decentered from the optical axis, and forms an image of the light emitting surface on the optical card 27. In this case, the light image formed by the light emitting diode 28 on the optical card 27 becomes a reproducing light beam as indicated by reference numeral 30 in FIG. Then, the relative distance between the reproduction light beam 30 and the light spot 271 due to the pulse emission of the semiconductor laser 21 described above is the optical axis of the recording light beam before incidence on the objective lens 26 during reproduction of the position of the optical head and reproduction. The setting is made by giving a relative angle difference to the optical axis of the working light beam 30.

The reproducing light beam 30 formed by the light-emitting diode 28 on the optical card 27 is modulated in light quantity depending on the presence or absence of the track guide 272 and the pit 274 on the optical card 27 and is specularly reflected to be a reproducing light beam. The light passes through the objective lens 26 in the opposite direction and is guided to the deflecting beam splitter 25 in the state of substantially parallel light. Further, the reproduction light beam 30 holds almost P deflection because it is specularly reflected, almost passes through the deflection beam splitter 25, is further guided through the reflection mirror 31 to the condenser lens 32, and the condenser lens 32. Light is condensed by the half mirror 33 and is split by the half mirror 33.
The image is enlarged and projected as an optical image on the optical card on the light receiving surface of the.

In this case, in such an optical system, the reproduction light beam 30 is made incident on a position decentered from the optical axis of the objective lens 26 to perform so-called off-axis type focus detection, and the focus photodetector 35 is used. For example, a two-divided light receiving element for detecting the movement of the image of the reproduction light beam spot due to the focus shift is used.

FIG. 4 shows an example of an optical image projected on the photodetector 34. In this case, the light receiving elements 341a to 341i for reproduction and the light receiving elements 342a and 342b for tracking are arranged on the photodetector 34,
The reproduction light beam 30 that has been magnified and projected is focused at an appropriate position on these light receiving elements. The tracking light-receiving elements 342a and 342b here are the track guides 2 due to the track shift due to the difference in the amount of received light.
A change in the position of the image 72 is detected as a change in the amount of received light, and a tracking error signal is generated. Further, the reproducing light receiving elements 341a to 341i are configured to simultaneously detect the presence or absence of the pit 274 in each track 273 by a change in the light amount and output a reproduction signal. FIG. 5 is for explaining an example of performing track access by such an optical information recording / reproducing apparatus.

In this case, similarly to FIGS. 3 and 4, the track guide 272 is a track formed between these track guides 272 and the reference numeral 30 is 9.
Showing the reproducing light beam across the track 273 of the book,
Reference numerals 341a to 341i denote reproducing light receiving elements for reproducing information on each track 273 irradiated with the reproducing light beam.

However, in such an optical system for multi-track reading, nine reproducing light-receiving elements 341a to 341a-3 are used.
Since 41i is provided, a plurality of track addresses where the reproduction light beam 30 is currently located continuously exist, but here, for the sake of convenience, the reproduction light receiving element 341 is provided.
Of the a to 341i, the address AD of the track 272 corresponding to the central reproducing light receiving element 341e is set as the address where the current reproducing light beam 30 is located.

In this state, a host computer (not shown) gives an instruction to reproduce data at a certain track address. In this case, assuming that the designated track address is AD1, the reproducing light beam 30 is moved in the direction of arrow a in the figure by the difference between the track address AD currently located and the track address AD1 to be moved. Become.

In this case, it is assumed that the reproduction light beam 30 is stopped by three tracks before the target track address AD1 due to a rough access error. That is, it is assumed that the track address corresponding to the reproducing light receiving element 341e is stopped at the address AD0 which is three tracks before the track address AD1 of the movement target.

However, in this state, as is clear from the figure, the reproducing light-receiving element 341h of the nine reproducing light-receiving elements 341a to 341i is positioned corresponding to the track address AD1 as the movement target. Therefore, when the card side is moved in this state and the reproducing light beam 30 is relatively moved in the direction of the arrow b in the figure, the ID section 3a of the card is moved.
Therefore, the target track address A of this track
It is confirmed that it is D1 and the data is reproduced.

Therefore, in this way, by realizing the multi-track read by the reproducing light beam 30 which crosses nine tracks and the corresponding reproducing light receiving elements 341a to 341i, the currently positioned track is realized. Even if the moving distance from the address to the target track address is large, the data of the target track can be played back at once, and compared to the conventional method, only rough access is required. Since the processing by the dense access can be omitted, the two track scans required in the normal access can be performed once,
As a result, the processing time for data playback can be greatly reduced,
It is possible to increase the reproduction speed.

In the above-mentioned embodiment, the number of reproducing light beams 30 corresponding to the reproducing light beam 30 is 9, and the number of tracks that can be reproduced at one time is 9, but N ≧ 2G + 1.
Other numbers may be used as long as they satisfy the expression of.

By the way, from the above equation, the larger the number of tracks that can be reproduced at one time, the more the number of tracks that can be reproduced at one time can be used to find the target track address at one time with respect to the error of coarse access, and the reproduction time can be shortened. However, if the number of tracks that can be played back at one time is too large, the playback light beam spreads, causing degradation of the playback signal due to a decrease in the light amount per unit area, and degradation of the playback signal due to an increase in various optical aberrations. However, since various problems such as an increase in weight of the bed itself and an increase in cost occur due to the increase in size of the optical element, it is of course set within a practical range. Besides, the present invention can be appropriately modified and implemented within the scope of the invention.

[0038]

According to the present invention, the number of a plurality of light receiving means for simultaneously detecting information on a plurality of tracks of a recording medium irradiated with a reproducing light beam is set to N ≧ 2G + 1 according to an error ± G due to rough access. Therefore, even if the moving distance to the target track address is large, the data of the target track can be reproduced by one scanning. As a result, it is possible to omit the processing due to the dense access, which was required in the past, and to perform the track scanning only once, and it is possible to greatly reduce the processing time of the data reproduction and to dramatically improve the reproduction speed. Can be realized.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the concept of the present invention.

FIG. 2 is a diagram showing a schematic configuration of an embodiment of the present invention.

FIG. 3 is a diagram showing a schematic configuration of an optical card used in an embodiment.

FIG. 4 is a diagram showing an example of a light image projected on the photodetector of the embodiment.

FIG. 5 is a diagram for explaining an example.

FIG. 6 is a diagram showing an example of an optical card.

FIG. 7 is a diagram for explaining a data recording unit of an optical card.

FIG. 8 is a diagram showing a schematic configuration of an optical system of a conventional optical head.

FIG. 9 is a diagram for explaining a conventional optical head.

FIG. 10 is a diagram for explaining a conventional access method.

[Explanation of symbols]

21 ... Semiconductor laser, 22 ... Collimating lens, 23 ...
Shaping prism, 24 ... Aperture, 25 ... Deflection beam splitter. 26 ... Objective lens, 27 ... Optical card, 271 ... Optical spot, 272 ... Track guide, 273 ... Track,
274 ... Pit, 28 ... Light emitting diode, 29 ... Collimating lens, 30 ... Reproducing light beam, 31 ... Reflecting mirror, 32 ... Condensing lens, 33 ... Half mirror, 34 ... Photodetector, 341a to 341i ... Reproducing light receiving Element, 342
a, 342b ... Tracking light receiving element, 35 ... Focusing photodetector.

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Naoaki Tani 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Co., Ltd. (72) Takami Sugaya 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd.

Claims (1)

[Claims] 1. A means for generating a reproducing light beam for simultaneously irradiating a plurality of tracks onto a recording medium having a plurality of tracks on which information is recorded, and information for a plurality of tracks irradiated with the reproducing light beam are simultaneously detected. And an optical head having a plurality of light receiving elements, the number N of the plurality of light receiving elements when the movement error when moving the optical head to a target track is ± G.
Is set to N ≧ 2G + 1, the optical information recording / reproducing apparatus.