JP3530108B2 - Optical recording medium and reproducing apparatus therefor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium having a plurality of planar optical waveguide type recording layers having a periodic light scattering factor and a reproducing apparatus therefor.

[0002]

2. Description of the Related Art In recent years, there has been a rapid increase in demand for large-capacity memories that are compact and easy to carry, including mobile computing. As one of the methods for realizing a large-capacity memory at low cost, a planar optical waveguide type optical recording medium in which data is embedded (recorded) in a planar optical waveguide as a periodic light scattering factor and the optical waveguides are stacked is proposed. (See, for example, Japanese Patent Laid-Open No. 11-345419).

FIG. 1 shows a schematic structure of an example of a conventional optical recording medium of this type and a reproducing apparatus therefor. In the optical recording medium 1, a plurality of core layers and clad layers are alternately laminated, or a plurality of core layers sandwiched by clad layers are laminated to form a clad layer (holding layer) above and below the core layer (optical waveguide layer). ) Is a multi-layered planar optical waveguide recording layer.

In each recording layer, the data is a repetitive pitch about the wavelength of light propagating through the optical waveguide layer, which is periodically formed in the optical waveguide layer or the retaining layer near the interface between the optical waveguide layer and the retaining layer. Is recorded as a periodic light scattering factor consisting of a large number of irregularly shaped lines with

To reproduce data, the light (incident light) 3 emitted from the laser light source 2 is converted into the incident position 11 on the target recording layer.
The light is propagated through the optical waveguide layer of the recording layer and is scattered by the periodic light scattering factor, and the reproduced light 4 is generated and imaged by the image sensor 5. At this time, since the incident light 3 does not couple with other recording layers, only the data from the target recording layer can be obtained and the crosstalk between the adjacent recording layers can be suppressed low.

[0006]

As described above, the optical recording medium using the planar optical waveguide type recording layer can be increased in capacity and is promising in the future, but in order to read data without error, the alignment is required. While it is necessary to couple incident light to the recording layer accompanied by focusing and focusing, there is no method for performing these at high speed and easily, which has been an obstacle to the realization of a device.

An object of the present invention is to enable an incident light to be coupled to a recording layer at high speed and easily in an optical recording medium having a plurality of planar optical waveguide type recording layers having a periodic light scattering factor. Another object of the present invention is to provide an optical recording medium.

Another object of the present invention is to provide a reproducing apparatus which can combine incident light into the recording layer of the above-mentioned optical recording medium at high speed and easily and can read data without error and at high speed. is there.

Another object of the present invention is to provide a reproducing apparatus capable of quickly and easily accessing incident light to a desired recording layer of the above-mentioned optical recording medium and reading desired data without error and at high speed. To provide.

[0010]

In order to solve the above-mentioned problems, the present invention comprises a core layer and clad layers above and below the core layer, and images data by scattered light generated when light is propagated to the core layer. an optical recording medium formed by stacking a plurality of planar optical waveguide type recording layer having a periodic light scattering factors that reproducibly recorded as, the periodic light-scattering factors the co
A light having a large number of irregular lines having a repeating pitch of about the wavelength of light propagating through the core layer, which is periodically formed in the core layer or the clad layer near the interface between the layer and the clad layer In the recording medium, the optical recording medium
The incident light may be on the front surface and / or the back surface of the body or both.
The cladding mode that propagates when coupled to the cladding layer.
A scattering factor having a function of scattering the propagation light of the optical disk and condensing it to the outside of the optical recording medium is provided (Claim 1).

According to the above construction, the scattering factor having a light collecting function is provided on the front surface, the back surface, or both of them, so that the incident light is correctly coupled to the recording layer and is scattered in the core layer. the light does not reach, the incident light is not properly coupled to the recording layer, the core layer and Kura
Since the light reaches the scattering factor when it is diffused in the head layer, it is possible to detect whether the incident light is correctly coupled to the recording layer by the amount of the light scattered and condensed by the scattering factor. can do.

A grating lens can be used as the scattering factor (claim 2).

[0013] In the present invention, the light emitted from the light source, is coupled to the recording layer of the optical recording medium according to claim 1 or 2, produced is scattered by the periodic light-scattering factor of the recording layer in the reproducing apparatus for reproducing data by imaging the reproduction light by the imaging device, disposed at a position where the scattered light due to scattering factors provided <br/> on the optical recording medium member is condensed
The light amount detecting means for detecting the light amount of the scattered light , the driving mechanism for relatively changing the positional relationship between the light emitted from the light source and the optical recording medium, and the light amount detected by the light amount detecting means are minimized. Thus, a control means for controlling the positional relationship in the focal position direction between the light emitted from the light source and the optical recording medium is provided (claim 3).

According to the above construction, the light quantity detecting means detects the light quantity of the scattered light due to the scattering factor, and the control means
By changing the positional relationship between the light emitted from the light source and the optical recording medium in the focal position direction so that the amount of light is minimized, the focal position of the incident light can be rapidly transferred to the recording end surface of the optical recording medium. Can be easily combined.

[0015] In the present invention, the light emitted from the light source, is coupled to the recording layer of the optical recording medium according to claim 1 or 2, produced is scattered by the periodic light-scattering factor of the recording layer in the reproducing apparatus for reproducing data by imaging the reproduction light by the imaging device, disposed at a position where the scattered light due to scattering factors provided <br/> on the optical recording medium member is condensed
The light amount detecting means for detecting the light amount of the scattered light , the driving mechanism for relatively changing the positional relationship between the light emitted from the light source and the optical recording medium, and the light amount detected by the light amount detecting means are minimized. As described above, a control means for controlling the positional relationship between the light emitted from the light source and the optical recording medium in the recording layer stacking direction is provided by the drive mechanism (claim 4).

According to the above construction, the light quantity detecting means detects the light quantity of the scattered light due to the scattering factor, and the control means
By changing the positional relationship between the light emitted from the light source and the recording layer in the recording layer stacking direction by the drive mechanism so that the light amount is minimized, the incident light can be transmitted to the recording layer of the optical recording medium quickly and easily. Can be combined with.

In the control means described above, the light quantity detected by the light quantity detecting means is minimized, and the data reproduced by the image pickup device, the servo component contained in the data, or both are maximized. By controlling so that the incident light can be more accurately coupled to the recording layer of the optical recording medium (claim 5).

Further, when the light emitted from the light source crosses the recording layer of the optical recording medium, the fluctuation of the light amount detected by the light amount detecting means is counted, and the light emitted from the light source crosses the recording layer of the optical recording medium. By providing a means for obtaining the number of moving layers, which is a different number, and a means for controlling the drive mechanism so that the number of moving layers matches the number of recording layers from the current recording layer to the desired recording layer, The incident light can quickly and easily access the desired recording layer of the optical recording medium (claim 6).

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows a schematic configuration of an embodiment of an optical recording medium and a reproducing apparatus therefor according to the present invention. In the figure, the same components as those in FIG. 1 are represented by the same symbols. That is, 2 is a laser light source, 3 is incident light, 4 is reproduction light, 5 is an image sensor, 10 is an optical recording medium, and 21 is a light amount detector.

The optical recording medium 10 has a structure similar to that of the conventional example shown in FIG. 1 and is provided with a grating lens 12 as a scattering factor having a condensing function on the surface (uppermost layer surface). . In the illustrated example, the medium 1
Although the grating 12 is formed on the emission end side of 0, it may be provided on the incident end side if it does not cover the data reproduction region. Further, instead of the front surface, it may be provided on the back surface (lowermost layer surface), or on both of them.

The light quantity detector 21 is for detecting the quantity of light scattered by the grating lens 12, and is composed of a photodiode or the like, and is arranged near the focal point of the grating lens 12.

FIG. 3 is an explanatory view of the principle of focus position alignment in the present invention.

In FIG. 1A, the incident light 3 emitted from the laser light source 2 is focused on the incident end face of the medium 10, and the incident light 3 is correctly coupled to the intended incident position 11 of the recording layer. It represents the state. At this time, most of the incident light 3 is confined in the core layer of the recording layer. The reproduction light 4 generated by the periodic light scattering factor of the recording layer is imaged by the image sensor 5 to obtain data. At this time, since the light hardly reaches the grating lens 12 provided on the surface of the medium 10, the output of the light quantity detector 21 is low.

On the other hand, FIG. 2B shows a state in which the focal position of the incident light 3 is not aligned with the incident end face of the medium 10 and is coupled not only to the core layer but also to the cladding layer at a considerable ratio. It represents. At this time, although the incident light 3 also has a component propagating through the core layer, it partially propagates as a multimode using the entire medium 10 as a waveguide.

At this time, the light also reaches the portion of the grating lens 12 provided on the surface of the medium 10, and as a result, the light is scattered by the grating lens 12, and the structure of the grating lens 12 causes the light amount detector. It is focused on 21. As a result, the light quantity detector 21 shows a high output.

As described above, the output of the light amount detector changes depending on the coupling state between the incident light and the recording layer, the coupling state between the incident light and the recording layer is discriminated, and the focus of the incident light is incident on the medium. The position can be adjusted accurately.

The focal position of the incident light (optical axis) is used here.
Although an example in which the direction coincides with the traveling direction of light in the medium has been shown, for example, as shown in Japanese Patent Laid-Open No. 11-345419, a 45 degree mirror is formed on the incident end face, and a 45 ° mirror is formed on the medium surface. It goes without saying that the principle of the present invention can be applied even to a configuration in which light is incident vertically.

Further, by using the above-mentioned principle, it is possible to align the incident light with an arbitrary recording layer among the recording layers laminated.

FIG. 4 is an explanatory view of the principle of recording layer alignment in the present invention.

FIG. 3A shows the case where the focal position of the incident light 3 is on the incident end face of the medium 10 and is on the core layer. As described with reference to FIG. When the light beam is accurately positioned at the incident position 11 on the recording layer, the energy transmitted in the cladding mode is low, and therefore the light condensed by the grating lens 12 is hardly detected by the light amount detector 21.

On the other hand, FIG. 3B shows the case where the focal position of the incident light 3 is on the incident end face of the medium 10, but is on the cladding layer between the core layers, As described in FIG. 3, when the incident light 3 is incident on the cladding layer between the core layers, almost all the energy of the incident light 3 propagates in the cladding mode. At this time, this propagating light is scattered by the grating lens 12, and this scattered light can be detected by the light quantity detector 21.

As described above, when the focal position of the incident light is aligned with the incident end face of the medium, it is determined from the output of the light amount detector whether the incident light is coupled with the core layer or the clad layer. can do.

Furthermore, the incident light can be positioned (accessed) by selecting a desired recording layer from a plurality of laminated recording layers by using the above-mentioned principle.

That is, according to the above-mentioned principle, it can be seen that when incident light moves across the recording layer, the output of the light amount detector fluctuates, but this fluctuation (increase / decrease) changes the number of recording layers crossed, that is, moves. It can be seen that this matches the number of recording layers.
Therefore, the number of moving layers of incident light can be obtained by counting the increase / decrease in the output of the light amount detector with a counter or the like. For example, the number of moving layers can change from the current recording layer to the desired recording layer. It can be seen that rough positioning of the interlayer movement of the incident light can be performed by moving the incident light so as to match the number.

When the medium is fixed and the incident end face is always near the focal position of the laser light source, the incident light can be coupled to the core layer only by the principle described in FIG. However, when the medium is exchangeable, it is difficult to completely couple the incident light to the waveguide simply by scanning the incident light. However, FIG. 3 and FIG.
By using the method explained in the above together, it is possible to realize a perfect combined state.

FIG. 5 shows a specific embodiment of the reproducing apparatus of the present invention. In the figure, 22 is a drive for relatively changing the positional relationship between the light 3 emitted from the laser light source 2 and the medium 10. A mechanism, 23 is a drive circuit of the drive mechanism 22, and 24 is a control circuit. FIG. 6 shows a flowchart of the operation sequence.

First, the control circuit 24 controls the drive mechanism 22 via the drive circuit 23 to move the incident light 3 from the laser light source 2 in the stacking direction of the medium 10 and align it with mechanical accuracy. Since the NA of the incident light is almost equal to the NA of the recording layer of the medium 10, even with positioning with mechanical accuracy,
It is possible to meet the condition that the diameter of incident light is smaller than the thickness of the clad layer. In this case, the incident light is either coupled to the cladding layer and not coupled to the core layer at all, partially coupled to the core layer, or coupled to the core layer. Become.

Next, the control circuit 24 controls the drive mechanism 22 to scan the incident light 3 in the stacking direction. At this time, by searching for a position where the output of the light quantity detector 21 is minimized, it is possible to match the state in which the incident light 3 is coupled around the core layer.

At this time, in addition to the output of the light quantity detector 21,
The light amount output of the CCD for data imaging, the light amount of the servo signal provided in each layer, and the like may be used together. In that case, it suffices to search for a point where the output of the light amount detector 21 is minimum and the CCD or servo output is maximum.

Even in this case, since the focal position of the incident light 3 does not always coincide with the incident end face of the medium 10, the presence of the cladding mode in addition to the reproduced data reproduced by propagating through the core. Considered the light quantity detector 21
May not be zero.

Subsequently, the control circuit 24 controls the drive mechanism 22 to finely move the incident light 3 in the optical axis direction. When the focus position moves in a direction that matches the incident end face, the contribution of the cladding mode decreases and the light amount detected by the light amount detector 21 decreases,
When the incident light 3 is almost completely coupled to the core layer, it is considered that the output of the light amount detector 21 becomes almost zero. Therefore, if the focal position of the incident light 3 is adjusted so that the output of the light quantity detector 21 is minimized, the optimum incident condition can be realized.

It is needless to say that the CCD and the servo signal strength can be added to the judgment standard in addition to the output of the light quantity detector 21 in the focus position adjustment.

According to the sequence described above, it becomes possible to easily couple the incident light to the recording layer of the optical recording medium only with the relatively simple numerical value of the light intensity. A photodiode or the like can be considered as the light amount detector, but the operation speed thereof is extremely high, so that the incident position can be quickly adjusted.

[0045]

As described above together with the embodiments, according to the present invention, a scattering factor having a condensing function is provided on the front surface and / or the back surface of the planar optical waveguide hologram. Since the scattered light intensity makes it possible to quickly adjust the position of the incident light, it is possible to provide a multiple hologram reading device capable of high-speed data transfer with a large capacity, and the effect thereof is extremely large.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a conventional optical recording medium and a reproducing apparatus thereof.

FIG. 2 is a schematic configuration diagram showing an example of an embodiment of an optical recording medium and a reproducing apparatus thereof according to the present invention.

FIG. 3 is an explanatory diagram of the principle of focus position adjustment in the present invention.

FIG. 4 is an explanatory view of the principle of recording layer alignment in the present invention.

FIG. 5 is a configuration diagram showing a specific embodiment of a reproducing apparatus of the present invention.

FIG. 6 is a diagram showing an example of a control flowchart of the playback device.

[Explanation of symbols]

2: laser light source, 3: incident light, 4: reproduction light, 5: image sensor, 10: optical recording medium, 11: incident position, 12: grating lens, 21: light amount detector, 22: drive mechanism,
23: drive circuit, 24: control circuit.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI G11C 13/04 G06K 19/00 D (72) Inventor Masahiro Ueno 2-3-1 Otemachi, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Stocks In-house (72) Inventor Manabu Yamamoto 2-3-1 Otemachi, Chiyoda-ku, Tokyo Inside Nippon Telegraph and Telephone Corporation (56) References JP2000-19939 (JP, A) JP2000-19940 (JP, A) JP-A-9-101735 (JP, A) JP-A-10-224043 (JP, A) JP-A-11-345419 (JP, A) JP-A-2000-21030 (JP, A) JP-A-2000-67204 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G11B ⁷ /00-7/30 G03H 1/00-5/00 G06K 7/00-7/14 G06K 19/00- 19/08 G11C 13/00-13/08

Claims (6)

(57) [Claims] 1. A consists core layer and upper and lower cladding layers thereof, data, plane having a periodic light scattering factors that reproducibly recorded as an image by scattered light generated when the by propagating light in the core layer an optical recording medium formed by stacking a plurality of optical waveguide type recording layer, the periodic light-scattering factors periodically to the core layer or the cladding layer in the vicinity of the interface between the cladding layer and the core <br/> layer Formed on the front surface or the back surface of the optical recording medium, or both of them , in an optical recording medium that is a large number of lines having an uneven shape having a repeating pitch of about the wavelength of light propagating through the core layer .
The crack that propagates when incident light is coupled into the cladding layer.
Outside of the optical recording medium by scattering the propagation light in the Ding mode
An optical recording medium, characterized in that a scattering factor having a function of condensing light is provided on the optical recording medium. 2. The optical recording medium according to claim 1, wherein a grating lens is used as the scattering factor. The 3. A light emitted from the light source, is coupled to the recording layer of the optical recording medium according to claim 1 or 2, imaging the reproduction light generated is scattered by the periodic light-scattering factor of the recording layer in the reproducing apparatus for reproducing data by imaging the element, light scattered by the scattering factors provided in the optical recording medium member condensing
A light amount detecting means arranged at a position where light is emitted, for detecting the light amount of the scattered light , a drive mechanism for relatively changing the positional relationship between the light emitted from the light source and the optical recording medium, and detected by the light amount detecting means. A reproducing device comprising: a control unit that controls the positional relationship between the light emitted from the light source and the optical recording medium in the focal position direction so as to minimize the amount of light to be emitted. 4. The reproduction light generated by combining the light emitted from the light source with the recording layer of the optical recording medium according to claim 1 and being scattered by the periodic light scattering factor of the recording layer. in the reproducing apparatus for reproducing data by imaging the element, light scattered by the scattering factors provided in the optical recording medium member condensing
A light amount detecting means arranged at a position where light is emitted, for detecting the light amount of the scattered light , a drive mechanism for relatively changing the positional relationship between the light emitted from the light source and the optical recording medium, and detected by the light amount detecting means. A reproducing device comprising: a control unit that controls the positional relationship between the light emitted from the light source and the optical recording medium in the stacking direction of the recording layers so as to minimize the amount of light to be emitted. 5. The light quantity detected by the light quantity detecting means is minimized, and the data reproduced by the image pickup device, the servo component contained in the data, or both are controlled to be maximized. The reproducing apparatus according to claim 3 or 4, characterized in that: 6. The light emitted from the light source crosses the recording layer of the optical recording medium, and the variation in the light amount detected by the light amount detecting means is counted, and the light emitted from the light source crosses the recording layer of the optical recording medium. The number of moving layers, which is the number of
6. A means for controlling the drive mechanism so that the number of moving layers matches the number of recording layers from the current recording layer to a desired recording layer, and means for controlling the driving mechanism. Playback device.