JPH09120541A - Optical information recording medium and optical recording/reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical information recording medium and an optical recording/reproducing device using it capable of performing surface discrimination (discrimination of rear surface reproduction from surface reproduction) with high reliability. SOLUTION: In the optical information recording medium, an information layer 3 is provided between two sheets of transparent substrates 2, 5 with nearly equal thickness, and both sides of the surface and rear surface are made capable of being irradiated by a light beam. The information layer 3 is provided with a first area 3A recording main information and a second area 3B forming a data pattern capable of easily discriminating the arrangement direction of the data. The second area 3B is regenerated directly from both surfaces of front/rear surface, and the surface discrimination is performed by a difference in the arrangement direction of the regenerated data. The data pattern is provided with e.g. at least three kinds of different lengths, and the lengths are increased or decreased gradually.

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 medium capable of high density recording, which is produced by bonding transparent substrates together, and an optical recording / reproducing apparatus using the same.

[0002]

2. Description of the Related Art Optical discs and optical cards are known as optical information recording media capable of optically recording or reproducing information. Most of these recording media use a semiconductor laser as a light source, and record or reproduce information by irradiating a minutely focused light spot through a lens. For example, a compact disc has a thickness of 1.
A printing layer composed of a transparent substrate of 2 mm, an information layer on which a reflective film such as a metal thin film is attached, and a protective layer for protecting this information layer, and for printing a label on the protective layer if necessary. Is provided. Uneven pits are formed by a molding technique on the surface of the transparent substrate that is in contact with the information layer, and information is recorded by changing the length and interval of the pits.
In reproducing information, the light beam from the optical head forms an image on the information layer. Since the phase of the reflected light is different from the surroundings in the part with pits, optical interference occurs and the reflectance decreases,
Since the interference does not occur in the part without the pit, the reflectance is high. As a result, information is reproduced as a change in reflectance.

At present, studies are being actively made to increase the recording capacity of these media. In order to increase the recording capacity of the optical disc, it is necessary to reduce the spot diameter D of the light beam. Assuming that the wavelength of the laser is λ and the numerical aperture of the objective lens is NA, the spot diameter D is proportional to λ / NA, and λ is short,
The larger the NA, the better the recording capacity. However, when a high NA lens is used, as described in, for example, US Pat. No. 5,235,581, coma aberration caused by a relative tilt between a disk surface called a tilt and an optical axis of a light beam becomes large, In order to prevent this, it is necessary to reduce the thickness of the transparent substrate. Further, when the transparent substrate is made thin, the mechanical strength becomes weak, and it is effective to adopt a structure in which other substrates are bonded together for reinforcement. Particularly, it is more effective if the two substrates have the same material and thickness. Is.

For example, a digital video disc
An optical disk called (hereinafter referred to as DVD) also uses a lens with a high NA. The DVD uses a red semiconductor laser with a short wavelength of 650 nm and an optical diameter that increases the NA of the objective lens to 0.6, and increases the recordable capacity on one side of an optical disc with a diameter of 120 mm to 5 GB and compresses a moving image for 2 hours or more. It is renewable. The NA of the DVD is as large as 0.45 to 0.6 as compared with the conventional compact disc (CD) standard and the like, and the light spot is also about 1 / 1.6 in diameter smaller. For the above-mentioned reason, the transparent substrate has a thickness of 1.2 mm while the CD is a single plate having a thickness of DV.
In D, two thin substrates each having a thickness of 0.6 mm are attached to each other to form an information layer therein.

The DVD is a first transparent substrate having a thickness of 0.6 mm,
It is composed of an information layer having a reflective film such as a metal thin film deposited thereon, a second transparent substrate, and an adhesive layer provided between the information layer and the second transparent substrate to bond the two, and if necessary, the second transparent substrate. A printing layer for printing a label is provided on the substrate.
Concave and convex pits are formed by a molding technique on the surface of the first transparent substrate which is in contact with the information layer, and information is recorded by changing the length and interval of the pits. That is, the uneven pit shape of the first transparent substrate is transferred to the information layer. The length and interval of the pits are shorter than that of the CD, and the track pitch, which is the pitch of the information tracks formed by the pit row, is also narrowed, and the areal recording density is improved. The surface of the first transparent substrate on which no pit is formed is a flat surface. The second transparent substrate is used for reinforcement,
The transparent substrate has the same material as the first transparent substrate and has the same thickness of 0.6 mm, and both sides are flat. In reproducing information, the light beam from the optical head forms an image on the information layer. Since the phase of the reflected light is different from that of the surrounding area in the pit area, optical interference occurs and the reflectance decreases, and in the area without the pit area, interference does not occur and the reflectance increases. As a result, information is reproduced as a change in reflectance.

[0006]

These optical discs can be attached to and detached from a reproducing device, and by exchanging the optical disc with the reproducing device, different music and images can be enjoyed. However, various problems occur during this attachment / detachment.

For example, by irradiating a light beam from the lower side with a CD
In a device that reproduces the information, normal reproduction is performed if the device is inserted with the front side facing down, but if it is inserted in the opposite direction, information is not reproduced because the light is blocked by the printing layer. Alternatively, in a CD in which the protective layer without the printing layer is exposed, light is transmitted, but the thickness of the protective layer is too thin compared to the transparent substrate, so large aberration occurs and the light beam cannot be focused on the information layer. , No playback signal can be obtained. However, there are cases where an unfamiliar user accidentally inserts with the back side facing down. Therefore, it is desirable for the user to know that the error has occurred by displaying an error, ejecting the disc from the playback device, or performing both at the same time. Most of the CD playback devices currently on the market have such a function. Therefore, determining the inserted surface (determining whether the surface positioned on the irradiation side of the light beam is the front surface or the back surface) is an important function in the optical disk device for attaching / detaching the optical disk. . (The surface means a surface on which a reproduction light beam is incident to reproduce information.)

Another conventional method for surface discrimination is described in, for example, Japanese Patent Laid-Open No. 58-155524. In one method described here, surface discrimination is performed based on the presence or absence of a reproduced signal. In the case of a CD, when reproducing from the front side, a reproduction signal (data signal) of a predetermined level is obtained from the optical head to detect data, but even if light is irradiated from the reverse side, the reproduction is performed for the above reason. No signal can be obtained and data cannot be detected. The surface is discriminated by the presence / absence of reproduction data depending on the difference of the inserted surface.

However, since this conventional method discriminates the surface depending on the presence or absence of a reproduced signal, it cannot be applied to an optical disc such as a DVD having two transparent substrates of equal thickness bonded together. With DVDs, depending on the disc, a reproduction signal can be obtained from the optical head even when a light beam is emitted from the back side, and it may be determined that there is data on either side, and face determination cannot be performed. In the case of a disc having no printing layer on the back side or a disc having a printing layer only on a part thereof, even if the light beam is radiated from the back side, the second transparent layer having the same thickness as the first transparent substrate does not exist on the back side. Since the transparent substrate is used, the optical conditions are close to those when the light beam is irradiated from the surface. Therefore, the large aberration described in the CD does not occur. If the adhesive layer transmits light, the light beam will be focused on the information layer, and a reproduction signal will be obtained even if the level drop is somewhat lowered, and there will be data regardless of which side the light beam is emitted. , Face identification is not possible. Further, even if the insertion surface of the optical disk is correct, the reproduction signal cannot be obtained due to other factors such as a failure of the optical head or the circuit system. Therefore, an erroneous insertion of the disk, which is an operation error, and a device failure cannot be distinguished. As described above, the surface discrimination method has many drawbacks.

Another method disclosed in Japanese Patent Laid-Open No. 58-155524 uses a reflection type optical detector in which a light emitting diode and a photodiode for receiving light are combined to use a label (print surface) and information. Surface discrimination is performed using the difference in reflectance of the recording surface. However, in this method, it is necessary to provide an optical detector for surface discrimination in addition to the optical head, which increases the cost of the apparatus. In addition, the shape of the device becomes large.
Furthermore, this method cannot be applied to a disc on which the label side is not printed.

Further, most recording optical discs use a cartridge, and the surface is discriminated by the cartridge. However, since the cost of the cartridge is high, it is difficult to use the cartridge for consumer applications where low cost is required. When these recording optical disks are also used in the changer system, they may be used with the cartridge removed, and in this case, the front and back surfaces of the disks may be erroneously mounted on the changer. Therefore, there is a demand for a surface discriminating method that does not depend on the cartridge even in such a recording disc. Further, in the changer system, since the structure of the mechanism and its control system becomes complicated, failures and operation mistakes frequently occur, and a method for more surely identifying the causes thereof is desired.

An object of the present invention is to attach transparent substrates,
An optical information reproducing medium having an information layer for recording or reproducing therein and capable of discriminating surfaces at low cost and with high reliability, and an optical recording / reproducing apparatus using the same.

[0013]

An optical recording / reproducing medium according to the present invention comprises a first transparent substrate, a second transparent substrate, and an information layer provided between the first and second transparent substrates. The first transparent substrate is provided with pits representing information on the side in contact with the information layer, and the information layer has a first area for recording main information and a data pattern for discriminating the data array direction. And a second region. By making the optical thicknesses of the first and second transparent media substantially equal, the optical information recording medium can irradiate the information layer with light from both the front surface and the back surface. When reproducing the second area on this information layer,
Surface discrimination can be performed by the difference in the direction of the data array of the reproduced data pattern.

Preferably, the data pattern formed in the second area of the information layer may be recorded by a data modulation method different from that of the main information recorded in the first area of the information layer. Preferably, the data pattern recorded in the second area of the information layer has a different track pitch and recording density from the main information recorded in the first area. For example,
The data pattern may be recorded coarser than the main information. Further, preferably, the data pattern formed in the second region of the information layer has at least three different lengths,
Its length gradually increases or decreases. This enables data discrimination. Preferably, the entire length of the data pattern recorded in the second area of the information layer is 1/40 or less of the length of the track on the information layer. Preferably, the data pattern formed in the second area of the information layer is repeatedly formed a plurality of times in the second area of the information layer. Preferably, the information layer and the second transparent substrate are adhered by an adhesive layer, and the thickness of the adhesive layer is 100 μm or less. The thickness of the information layer is preferably 5 to 200 nm.

Preferably, a label layer on which an image (graphics, characters, etc.) is drawn is further provided on the second transparent substrate.
The label layer is provided so as to substantially avoid the second area of the information layer facing the label layer. This prevents the label layer from interfering with the surface discrimination. Preferably, the second region of the information layer comprises a region forming the data pattern and a region having a reflectance different from that of the region forming the data pattern.
An image that can be seen with the naked eye is formed in the area (1) due to the difference in reflectance. Preferably, a region having a reflectance different from that of the region forming the data pattern is provided so that the image can be normally observed from the back surface. When inserting an optical information reproducing medium, the user can avoid erroneous insertion in many reproducing devices that can be inserted properly with the back side facing up.

An optical recording / reproducing apparatus according to the present invention optically records information on an optical recording / reproducing medium having an information layer having a second area in which a data pattern for discriminating the data array direction is formed. A device for reproducing, a drive device for rotating the optical information recording medium, an optical head for reading a signal formed on the information layer of the optical information recording medium, and a transfer of the optical head on the second area of the information layer. And a discriminating means for discriminating the arrangement direction of the data of the data pattern from the signal received from the optical head in the second area. The second area on the information layer is reproduced, and the surface is discriminated by the direction of the arrangement of the reproduced data pattern. As a result, the surface discrimination can be performed with high reliability. Preferably, the discriminating means includes a first counter means for counting the length of the signal in the data pattern received from the optical head, and a length of the first signal counted by the first counter means. Comparing the length of the first signal with the length of the second signal following the first signal and the result of the comparison received from said comparing means to detect a continuous increase or decrease in the length of the signal in the data pattern. And second counter means. Preferably, it further comprises alarm means for giving an alarm to the user when the determination means determines the erroneous insertion of the optical recording / reproducing medium.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an optical information recording medium and an optical information recording apparatus of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view showing a read-only type optical disc, which is an embodiment of an optical information recording medium according to the present invention, from the center to the outermost periphery. This optical disc is an example of an optical information recording medium having a transparent substrate attached thereto and an information layer for recording or reproducing therein. As shown in the lower side of FIG. 1, the optical disc 1 includes a first transparent substrate 2, an information layer 3 to which a reflective film such as a metal thin film is attached, and an information layer 3.
And a second transparent substrate 5, which are provided between the second transparent substrate 5 and the second transparent substrate 5, and a label layer (printing layer).
No. 6 is sequentially laminated. In the figure, the right side indicates the center side and the left side indicates the outer peripheral side. R ₁ , R ₂ , R ₃ and R ₄
Represents the radius at the position where these symbols are written. R ₄
Corresponds to the outermost circumference of the optical disc 1. In this optical disc 1, a lower surface on which a light beam is incident and which reproduces information is referred to as a front surface A, and an upper surface opposite thereto is referred to as a rear surface B. The optical disc 1 is mounted on the reproducing device and rotates counterclockwise when viewed from the light beam irradiation surface side (lower side in FIG. 1).

A characteristic of this optical disc is that it is possible to detect an erroneous insertion of the optical disc. Here, the first area 3A
Is provided in a portion between the radii R ₂ and R ₃ of the information layer 3 and records main information as in the conventional case. The second region 3B is the first
It is provided in the range between the radii R ₁ and R ₂ inside the area of.
Since the relative movement directions of the light spot and the information track are different depending on the surface mounted on the reproducing apparatus, the data arrangement of the reproduction signal is different. Therefore, paying attention to this fact, a data pattern that makes it easy to detect the direction of the data array is provided with the second area 3 of the information layer 3.
Form in B. Then, the surface determination is performed based on the difference in the reproduction data pattern in the second area 3B.

The optical disc will be described in more detail below. The first transparent substrate 2 and the second transparent substrate 5 are preferably made of a material (eg, a resin material such as a polycarbonate resin or a PMMA resin) that has low light absorption and high strength in the wavelength region of the irradiation light beam. Made
Most commonly, these transparent substrates 2 and 5 are formed by injection molding a molten resin, but a glass material may be used for the transparent substrate depending on the application. The optimum values of the thicknesses t ₁ and t ₂ of the first transparent substrate 2 and the second transparent substrate 5 differ depending on the diameter of the disk, and the optimum values are determined from the viewpoint of recording density and mechanical strength.

Pits are formed along the track on the surface of the first transparent substrate 2 which is in contact with the information layer 3. Information is recorded by changing the length and interval of the pits. The second transparent substrate 5 is a transparent substrate whose both sides are flat. And the first
The transparent substrate 2 and the second transparent substrate 5 have refractive indices n ₁ and n ₂ that are substantially equal to the thicknesses t ₁ and t ₂ , respectively. In addition,
The method for molding the transparent substrate and the mastering method for recording information are known as optical disc manufacturing processes, and are not the essence of the present invention, and therefore detailed description thereof will be omitted.

In the information layer 3, pits are formed in a spiral shape, and an information track (not shown) is formed by this pit row. In the information layer 3, the front surface A side of the optical disc 1 is the front side of the information layer, and the back surface B side is the back side of the information layer. When applied to a reproduction-only disc, the information layer 3 has a predetermined reflectance with respect to the wavelength region of the light beam to be radiated and can easily transfer the pits and depressions formed on the first transparent substrate 2 Is desirable. A thin film of a metal material made of Au, Al, Cr, Cu, or an alloy thereof is one that satisfies these conditions. Further, the depth of the uneven pits transferred to the information layer 3 is λ
Then, the optical length (the product of the refractive index of the first substrate 2 and the distance) is about λ / 4 to λ / 8. When polycarbonate or PMMA resin is used for the first substrate 2, the refractive index is about 1.5.
When λ is 650 nm, the physical length is about 108 to 54 nm, which is an extremely small value compared with the thickness of other layers.

Since the front side of the information layer 3 is in contact with the first transparent substrate 2, the uneven pit shape is accurately transferred. In the conventional optical disc, it is not necessary to read the information from the back surface B side. However, in the present invention, it is necessary to read the signal from the back surface B side at least in the second area of the information layer. Since the depth of the pits is shallow as described above, if the thickness of the information layer is too thick, the pits will be buried and the pits cannot be formed on the back side of the information layer 3. Further, it takes a long time to form a thick information layer, and productivity is deteriorated.
On the other hand, if it is too thin, the information layer 3 transmits light and the reflectance is lowered. Therefore, the thickness of the information layer 3 used in this embodiment is preferably in the range of about 5 to 200 nm in the case of a read-only disc.

On the information layer 3, as shown in FIG. 1, a first area 3A is provided on the outer peripheral portion and a second area 3B is provided on the inner peripheral portion.
Main information is recorded in the first area 3A. This main information is the digitized video signal or music signal,
Alternatively, when applied to a disk for a computer, it means a program, data, etc. handled by the computer.
The data pattern is repeatedly recorded in the second area 3B. This data pattern is a pattern that can be read from both surfaces of the optical disc 1 and that allows easy determination of the data array direction. Second area 3B
May be provided with a management information area in which other management information is recorded. The management information is, for example, information such as a control track indicating the conditions for recording / reproducing a disc, or the like, or information regarding file management such as a directory, and the like, which has an optimum format for a target device. It may be used, and since it is not the essence of the present invention, detailed description thereof will be omitted.

Next, the adhesive layer 4 will be described. The adhesive layer 4 needs to transmit light in at least the second region with respect to the wavelength region of the irradiation light beam. Further, it is desirable that the generated aberration be small. As a bonding method suitable for the bonding layer 4, for example, there is a method using an ultraviolet curable resin (UV resin). However, the adhesive layer may be formed by any method as long as foreign matter such as air bubbles is less mixed, light is transmitted in the irradiation wavelength range, and adhesive strength is secured. The thickness t ₃ of the adhesive layer 4 depends on the adhesive strength, the formation of a uniform adhesive layer, the material cost of the resin material used, and
From the viewpoint of the time required for curing and the like, the value is about several to 100 μm. Further, from the viewpoint of suppressing the occurrence of aberration when the light beam is emitted from the back surface B, the thickness needs to be 100 μm or less. Next, the print layer 6 will be described. Print layer 6
Is a graphic or character that allows the user to visually recognize the content recorded on the optical disc 1, or a beautiful graphic or character printed to enhance the commercial value, and is usually called a label. It is exposed. The printing layer 6 can be formed by using a known printing technique such as silk printing and offset printing.

As shown in FIG. 1, the label area in which the printing layer 6 is formed is provided substantially avoiding the second area 3B of the information layer 3 facing. If the area between the radii R ₁ and R ₂ where the second area is formed is widened, the first area 3A for recording the main information becomes narrow and the storage capacity is reduced. Therefore, the second region is not made wider than necessary, and the radius R from the back surface B is increased.
It is desirable to be able to regenerate the entire area between ₁ and R ₂ .
Therefore, when the spread of the light beam on the back surface B formed when the light beam is irradiated from the back surface B side is δ ₁ ,
It is necessary to provide the printing layer 6 while avoiding at least the region between the radii (R ₁ −δ ₁ ) and (R ₂ + δ ₁ ) of the back surface B. In FIG. 1, for the distances δL ₁ and δL ₂ from the edge of the printing layer 6 where δL ₁ > δ ₁ and δL ₂ > δ ₁ , the radii (R ₁ −δ ₁ ) and (R ₂ +
The printing layer 6 is provided while avoiding the region between δ ₁ ). Here, when the thickness of the second transparent substrate 5 is t ₂ , the refractive index is n _2, and the numerical aperture of the optical system of the optical head is NA ₁ ,
The focusing angle θ ₂ of the light beam exiting the transparent substrate 5 is sin
⁻¹ (NA ₁ / n ₂ ), and the light beam spreads on the second transparent substrate 5 by δ ₁ = (t ₃ + t ₂ ) tan (θ ₂ ). Usually, the thickness t ₃ of the adhesive layer 4 is sufficiently smaller than the thickness t ₂ of the transparent substrate 5, so that δ ₁ = t ₂ tan (θ ₂ ).

Now, as shown enlarged on the upper side of FIG.
A light beam 7 from an optical head (not shown) is emitted from the surface A, is focused on the information layer 3, and forms an image on the information layer 3 as a light spot 8. The reflected light from the information layer 3 returns to the optical head and the signal is reproduced. In the pitted portion of the information layer 3, the reflected light is out of phase with the surroundings, so that optical interference occurs and the reflectance is lowered, and in the pitless portion, the interference is not generated and the reflectance is increased. As a result, information is reproduced as a change in the amount of reflected light.

FIG. 2 is a schematic view of the recording layer 3 when viewed from the light beam irradiation side when the optical disc 1 is inserted into a reproducing apparatus so that the surface A is irradiated with the light beam as shown in FIG. To indicate. A spiral track that rotates clockwise is formed from the inner circumference to the outer circumference. And
A second region 3B shown by a thick line is provided on the inner circumference,
A first region 3A indicated by a thin line is provided on the outside thereof.
In the first area, ..., S1, S2, S3, S on the drawing.
4, S5, S6, S7, S8, ... Record the main information in a predetermined recording unit sequentially.
These recording units are usually called sectors or blocks.

The light spot 8 irradiated on the track is
It is controlled to be positioned on the track by a tracking control means (not shown). Since the optical disc 1 rotates counterclockwise, the optical head changes the recording unit ... S1 →
The reproduction is performed from the inner circumference side to the outer circumference in the order of S2 → S3 → S4 → S5 → S6 → S7 → S8.

The feature of this embodiment is that erroneous insertion of an optical disc can be detected. As mentioned earlier, paying attention to the fact that the data array of the reproduced signal differs due to the difference in the relative movement direction of the light spot and the information track due to the surface mounted on the reproducing device, and the data pattern that makes it easy to detect the direction of the data array. Is formed in the second area of the information layer. Then, as described below, surface discrimination is performed based on the difference in the data array of the reproduction data pattern in the second area.

With reference to FIG. 3, description will be given of a case where the optical disk according to the present invention is erroneously inserted into the reproducing device and a light beam is irradiated to the back surface B side. The optical disc 1 is shown in FIG.
Contrary to the above case, the back surface B is located on the lower side and the front surface A is located on the upper side. The light beam 7 is applied to the back side of the information layer 3 through the second transparent substrate 5 and the adhesive layer 4 thinner than the second transparent substrate 5. Therefore, the optical length until the light beam 7 is incident on the surface of the base material and reaches the information layer 3 becomes a value close to that when the light beam 7 is irradiated from the surface A side shown in FIG. A light spot 8'is formed on the back side of the.

FIG. 4 shows the information layer 3 when the optical disc 1 is viewed from the side irradiated with the light beam in the state shown in FIG. Contrary to FIG. 2, spiral tracks that rotate counterclockwise are formed from the inner circumference toward the outer circumference. Therefore, when the optical disc 1 is also rotated counterclockwise, the relative movement directions of the light spot 8'and the track are opposite. That is, the order of the reproduced signals is opposite to that in the case of FIG. 2, and in the reproduction order of the recording unit,
... S8, S7, S6, S5, S4, S3, S2, S1 ...
・ ・Therefore, the case of reproducing from the front surface A and the case of the rear surface B
When played from, the temporal order of the played signal
(Data array) is also reversed. That is, since the spiral direction viewed from the light beam irradiation side is reversed due to the mounting surface, the relative movement direction of the information track and the light spot also changes, and as a result, the data array of the reproduced signal becomes opposite. By determining the relative movement direction of the light spot and the information track, the surface mounted on the reproducing device can be determined.

When there is no erroneous insertion shown in FIG. 1, the reproduced signal is output from the optical head as an analog signal,
This is subjected to analog signal processing, binarized, and then subjected to digital signal processing such as digital demodulation and error correction to obtain target information. However, in reproduction at the time of erroneous insertion as shown in FIG. 3, the reproduction signal can be obtained from the optical head, but the data array is reversed, so even if the above-described signal processing is performed, the target information can be obtained. Can't get There are already many well-known methods for these signal processing methods, and they are not the essence of the present invention, so a detailed description thereof will be omitted.

In the surface discrimination (discrimination between front surface reproduction and rear surface reproduction), the optical recording / reproducing apparatus moves the optical head in the inner peripheral direction of the optical disk and irradiates the second region 3B of the information layer 3 with the light beam. Then, the focus control is activated to form the light spot 7, and then the data formed on the information layer 3 is read from the optical head.

Hereinafter, the second region 3 formed on the information layer 3
The reading of the B data pattern will be described with reference to FIGS. In FIG. 5, the second region in the state shown in FIG. 2 is enlarged and shown in the upper part, and below it, the binarized signal D1 obtained by binarizing the signal reproduced from the optical head is shown. In the second area, three tracks TR1, TR2,
TR3 is formed by a pit row. On this track, for example, pits and pit intervals such as pits having a pit length L1 → pit intervals having a length L2 → pits having a pit length L3 → pits having a length L4 are provided as data patterns on which the arrangement direction can be easily discriminated. Those arranged in the order of intervals are repeatedly formed as one cycle (TD1). Two cycles are shown in FIG. In this data pattern, the pit length and the pit interval are in the relationship of L1 <L2 <L3 <L4 in one cycle, and L1,
The lengths of L2, L3, and L4 gradually increase from left to right in the drawing. This data pattern is
It is repeatedly formed in a spiral shape over the entire second region.

When the light spot is applied to this second area, the relative movement direction of the light spot and the track is from left to right as indicated by the arrow in the figure, and the reproduction signal is binarized. The signal D1 is "0" between pits and "1" between pits. At this time, the binarized signal D1
The length of "0" and the length of "1" are T1 → T2 → T3 →
It increases sequentially like T4. T1, T2, T3, T4
Is a pulse interval corresponding to the pit length and the pit interval, and T1 <T2 <T3 <T4. That is, the optical disc 1 is irradiated with the light beam from the front surface A side and the second information layer 3
When the area is reproduced, it is possible to obtain a signal whose length (the length of "1" or "0") sequentially increases. In other words,
When the signal of which the length gradually increases is obtained, it can be determined that the optical disc is properly inserted into the device.

Next, the case where the second area of the information layer 3 is reproduced from the back surface B shown in FIG. 3 will be described with reference to FIG. In the upper part of FIG. 6, the second region in the state shown in FIG. 4 is enlarged and shown, and below that, the binarized signal D1 obtained by binarizing the signal reproduced from the optical head is shown. Similarly, in the second region, the tracks TR1, TR2, TR3 indicated by the one-dot chain line are shown.
Is composed of a pit row. However, as a data pattern on this track, the pit interval is a pit interval having a length L4 → a pit having a pit length L3 → a length L
The pits are arranged in the order of the pit interval of 2 to the pit of pit length L1. This is because the spiral forming direction of the track is opposite to that in the state of being reproduced from the surface A as shown in FIG. 5, and in the data array of the reproduced signal, the length gradually decreases from left to right in the drawing. , Fig. 2
The opposite of the case.

Then, in this state, when the optical disc 1 is rotated counterclockwise as described in the description of FIG. 1, the length of the binarized signal D1 is gradually reduced as T4 → T3 → T2 → T1. To do. That is, when the second area of the information layer 3 is reproduced by irradiating the light beam from the back surface B side of the optical disc 1,
Contrary to the reproduction from the surface A, the signal becomes a signal whose length gradually decreases. Therefore, the direction of the data array can be detected by measuring the length of the binarized signal D1 and detecting whether the length is sequentially decreasing or increasing, and therefore, the direction from the surface A is reproduced. It is possible to determine whether or not the data is reproduced from the back surface B.

FIG. 7 shows an optical recording / reproducing apparatus applied when a data pattern whose length is sequentially increased as described in FIGS. 5 and 6 is formed in the second area of the information layer. . This device differs from the conventional optical recording / reproducing device in the part related to the second area. As in the conventional case, a drive unit 10 having a spindle motor (not shown) for rotating the optical disc 1 and a light source (semiconductor laser) 11 are provided.
Optical head 13 that irradiates the optical disc 1 with a light beam
Is provided. The optical head 13 focuses the light beam by the focus control device and forms a light spot on the optical disc 1. The optical head 13 is transferred by the transfer device 12 in the radial direction onto the first area and the second area on the information layer. Here, tracking control is also performed. The signal from the optical head 13 is amplified by the amplifier 14 and reproduced by the first area demodulation circuit 15. On the other hand, the data to be recorded is modulated by the first area modulation circuit 16 and recorded on the optical disc 1 by the optical head 13. The above configuration is similar to that of the conventional optical recording / reproducing apparatus. The apparatus further includes a second area demodulation circuit 17 and a surface discrimination circuit 18 for surface discrimination. The optical head 13 transferred to the second area by the transfer device 12 reads the data pattern in the second area, and the second area demodulation circuit 17 demodulates the read signal. The demodulated signal is discriminated by the surface discriminating circuit 18, which will be described in detail below, as to whether it is a front surface or a back surface. When it is determined that it is the back side, an error message is displayed by the warning circuit 19 to warn the user of erroneous insertion.

FIG. 8 shows an embodiment of the surface discriminating device 18. The surface discrimination device includes a pulse conversion circuit 30, a first delay circuit 31, a second delay circuit 32, a period counter 33, a first register 34, a second register 35, a digital comparator 36,
It comprises a first AND gate 37, a second AND gate 38, an up / down counter 39 and a microcomputer 40. 9 and 10 show waveforms at various parts of the surface discriminating apparatus for normal insertion and incorrect insertion.

With reference to FIGS. 8 and 9, the structure and operation of the surface discriminating apparatus when the surface A as shown in FIG. 1 is irradiated with the light beam and the second area of the information layer 3 is reproduced. explain. In the circuit shown in FIG. 8, the binarized signal D1 from the optical head is added to the pulse conversion circuit 30. On the other hand, the clock signal D2 is added to the pulse conversion circuit 30, the first delay circuit 31, the second delay circuit 32, and the period counter 33. The pulse conversion circuit 30 generates a pulse signal D3 synchronized with the clock signal D2 at the rising and falling edges of the binarized signal D1. The pulse signal D3 is applied to the first delay circuit 31 and the second register 35.
The first delay circuit 31 delays the signal D3 by one cycle (δT) of the clock signal and outputs a first delay signal D4. The signal D4 is added to the second delay circuit 32, the period counter 33, and the first register 34. Then, the second delay circuit 32 outputs the second delay signal D5 obtained by delaying the first delay signal D4 by δT to the first AND gate 37 and the second AND gate 38. Note that the pulse signal D3, the first delay signal D4, and the second delay signal D5 have the same cycle only with time delay.

The length counter 33 measures the period of the first delay signal D4 by the clock signal D2 and outputs the period count signal D6 whose value changes with time. The signal D6 is reset to "0" at the rising edge of the signal D4 and sequentially increases until the next rising edge.
Immediately before resetting to "0", final count values N1, N corresponding to the periods T1, T2, T3, T4 of the binarized signal D1.
2, N3, N4 are sequentially obtained. And this signal D6
Are sent to the first register 34. Note that T4>T3> T
Because of the relationship of 2> T1, the final count value is N4> N3
>N2> N1. The first register 34 fetches the final count values N1, N2, N3, N4 of the period count signal D6 in synchronization with the rising of the first delay signal D4 and holds this value until the next rising. And the first register 1
The two output signals D7 are applied to the second register 13 and the digital comparator 37. On the other hand, the second register 35 stores the output signal D7 of the first register 34 in synchronization with the rising of the pulse signal D3, and holds the value immediately before the output of the first register changes to the next final count value. Therefore, the output signal D8 of the second register 35 is delayed by one pulse of the pulse signal D3 from the output signal D7 of the first register. As shown in FIG. 8, the output signal D7 of the first register 34 changes as N4 → N1 → N2 → N3 → N4, while the output signal D8 of the second register 35 changes.
Changes as N3 → N4 → N1 → N2 → N3. The two output signals D7 and D8 are output to the digital comparator 36.

The digital comparator 36 numerically compares the two input signals D7 and D8 and outputs the first comparison result.
Two signals of the comparison signal D9 and the second comparison signal D10 are output. Here, the first comparison signal D9 is the signals D7 and D8.
Is “1” when D7 ≧ D8, and is “0” when D7 <D8. The second comparison signal D10 is “1” when the signals D7 and D8 are D7 ≦ D8, and is “0” when D7> D8. Therefore, as shown in FIG.
As for the comparison signal D9, the signal D7 is "N1" and the signal D8 is "N".
It is "0" only in the period A (see FIG. 9) which is 4 ", and is" 1 "in the other periods.
10 becomes "1" only in the period A. This period A
Occurs when the period of the binarized signal D1 decreases from "N4" to "N1", and is delayed by about one pulse in the period of the signal D3.

The first comparison signal D9 is sent to the first AND gate 37.
And the second comparison signal D10 is applied to the second AND gate 3
8 is added. On the other hand, the second delay signal D5 also has these A
It is added to the ND gates 37 and 38. Therefore, as shown in FIG. 9, the first AND gate 37 outputs the up signal D11 obtained by deleting the signal D5 in the period A, and outputs the up signal D11.
The ND gate 38 outputs the down signal D12 obtained by extracting the signal D5 in the period A. This up signal D11
And down signal D12 are respectively up / down counter 3
9 UP and DOWN terminals.

When a pulse is input to the UP terminal, the up / down counter 39 outputs the pulse difference signal D which is its output.
When the value of 13 is increased and a pulse is input to the DOWN terminal, the value of the pulse difference signal D13 is decreased. Thus, the difference in the number of pulses input to each terminal is output as the pulse difference signal D13. In the example shown in FIG. 9, the up / down counter 39 has T which is one cycle of the binarized signal D1.
In the period of D1, three up signals and one down signal are added. In this way, the count value of the output signal, the pulse difference signal D13, increases by 2.

The microcomputer 40 receives the pulse difference signal D13 and stores the value in the internal memory.
Inside the microcomputer 40, a positive reference value + Nr
And a negative reference value -Nr are set. Pulse difference signal D
When the value of 13 exceeds the positive reference value + Nr, it is determined that the cycle is sequentially increased as the arrangement direction of the reproduced data, and it is determined that the surface A is reproduced. On the contrary, when the signal D13 is a negative value and exceeds -Nr, it is determined that the cycle of the reproduced data is sequentially decreased and it is determined that the surface B is reproduced.

In the example shown in FIG. 9, the signal D13 coincides with the positive reference value + Nr at the right end of the figure, and it is detected that the cycle of the reproduced data pattern is successively decreased. Then, the microcomputer 40 determines that the surface A is reproduced. The microcomputer 40 issues a command to shift to the next operation based on this judgment,
For example, a search command for the first area is generated.

Next, referring to the block diagram of FIG. 8 and the waveform diagram of FIG. 10, the back surface B as shown in FIG. 3 is irradiated with a light beam, and the second region of the information layer 3 is reproduced. The operation of the surface discriminating device at this time will be described. In FIG. 10, since the data array of the binarized signal D1 is reversed, T4 → T3
→ T2 → T1 The pulse width decreases sequentially. Then, the pulse signal D3 also becomes a signal whose period is sequentially reduced like the pulse width of the signal D1. In addition, the first delay signal D4
Is a signal obtained by delaying the pulse signal D3 by δT, and the second delay signal D5 is a signal obtained by delaying the signal D4 by δT. Further, the final count value of the period count signal D6 sequentially decreases in the order of N4 → N3 → N2 → N1 in response to the change of the pulse width of the signal D1 becoming T4 → T3 → T2 → T1.
Therefore, the output signal D7 of the first register also sequentially decreases as N1 → N4 → N3 → N2 → N1, and the output signal D8 of the second register becomes a signal delayed by one pulse of the signal D3 with respect to the signal D7. → It changes like N4 → N3 → N2. As a result, the first comparison signal D9 becomes "1" only in the period B (see FIG. 10) in which the signal D7 is "N4" and the signal D8 is "N1", and the second comparison signal D10 is only in the period B. , "0". Therefore,
The up signal D11 is the second delay signal D in the period B.
5 is extracted, and one pulse is generated in one cycle of the binarized signal D1. Further, the down signal D12 is the signal obtained by deleting the signal D5 in the period B, and three pulses are generated in one cycle of the binarized signal D1. Therefore, the pulse difference signal D13 becomes a signal whose count value decreases by 2 and increases in the negative direction during the period of TD1 which is one cycle of the signal D1.

The microcomputer 40 receives the signal D13.
Is read, and when the value exceeds the negative reference value −Nr, it is determined that the back surface B is reproduced. In the case of FIG. 10, the signal D13 coincides with the negative reference value −Nr at the right end of the drawing,
As a result, it is detected that the cycle of the reproduction data pattern is decreasing. The microcomputer 40 determines that the back surface B is being reproduced at this point.

The microcomputer 40 performs an abnormality processing operation based on this judgment. That is, a command is issued to stop the irradiation of the laser beam and stop the control operation for stopping the focus control, the spindle motor control, and the like. Further, in order to inform the user of the incorrect insertion, an alarm device 19 gives a visual or audible warning as required. Alternatively, the optical disc 1 is ejected from the reproducing device, or both are performed at the same time. Alternatively, in a device such as a changer system, the host computer controlling the changer system is notified of the incorrect insertion.

The description of one embodiment of the optical disc and the surface discriminating method using the same is finished above, but various modifications can be made to this embodiment. For example, the data pattern in the second area provided in the information layer 3 may be concentric tracks instead of the spiral tracks described in FIG.

The first area 3A and the second area 3B of the information layer 3 may have different track pitches, pit widths, pit lengths, and pit intervals. In the first area 3A, the recording density must be increased in order to increase the capacity for recording main information. On the other hand, the second area 3B is an area used for surface determination, and the arrangement direction of data can be determined. If possible, the need for increasing the recording density is low. Rather, it may be preferable in some cases to form a data pattern having a low recording density that allows stable reading.

Further, in the second area 3B, a track formed of pits may not be formed, but a radial band extending from the center of the optical disc to the outer periphery as shown in FIG. 11 may be formed. The width of this band is the first low-reflectance band (width L that can identify the direction of the data array as described in FIGS. 5 and 6).
1) 61 → first high reflectance band (width L2) 62 → second low reflectance zone (width L3) 63 → second high reflectance zone (width L4) 64
Is defined as one cycle, and is repeatedly formed over the entire circumference of the second region. (One cycle is shown in FIG. 11.) Bands 61 to 64
The low reflectance band can be formed by removing the information layer by etching, and the high reflectance band can be formed by leaving the information layer as it is. It can also be realized by forming a narrow uneven band on the information layer. Further, the low reflectance bands 61 and 63 may be formed by uneven pits, and the portions without pits may be used as the high reflectance bands 62 and 64. Thus, the data pattern formed in the second area 3B may be recorded by a data modulation method different from the main information recorded in the first area 3A.

Further, the present invention is not limited to a read-only optical disk, but also an optical information recording medium such as a recordable optical disk or an optical disk in which a read-only area and a recording area are mixed on the same information layer, and the optical information recording medium. It can also be applied to the conventional optical recording / reproducing device.

The present invention is not limited to an optical disc having one information layer, but can be applied to an optical disc provided with a plurality of information layers. Further, the present invention can be applied to an optical information recording medium such as an optical disc having a plurality of information layers, in which a reproduction-only information layer and a recording information layer are mixed, and an optical recording / reproducing apparatus using the same. Particularly, in an optical information recording medium having a plurality of information layers, if a second area is provided for each information layer and the data pattern formed in the second area is different for each information layer, the mounting surface Not only the determination (determination of the front surface A and the back surface B), but which information layer is being reproduced can be determined. This information layer discrimination is also included in the category of surface discrimination of the present invention.

Next, the data pattern for determining the data array direction formed in the second area will be described. The data pattern used in the present invention does not have to sequentially increase the pulse width described in the embodiment, but may have the pulse width gradually decrease. Further, when a data pattern whose pulse width is sequentially increased or decreased is used, in the present embodiment, an example in which four types of data patterns having different lengths L1, L2, L3, and L4 are used has been described. . However, in general, if the data patterns have three or more different lengths, the arrangement direction of the data can be determined. The data pattern is not limited to the one in which the pulse width sequentially increases or decreases.

When discriminating between the front surface and the back surface of the information layer or discriminating the information layer of the optical information recording medium having a plurality of information layers, the information layer 3 can be discriminated in the shortest possible time after being inserted into the reproducing apparatus. desirable. Specifically, it is desirable to be able to make a determination almost simultaneously with the start of rotation of the spindle motor that drives the optical disc to rotate immediately after insertion. More specifically, the focus control system is activated and the motor is rotated by a known focus pull-in method. It is desirable that the focus be pulled in after a slight delay from the start, and the determination can be performed during acceleration before the motor reaches a predetermined rotation speed, and in a state where the tracking control is not operating. Therefore, a data pattern that is composed of three or more types of periods and is modulated such that the periods sequentially increase or decrease is
It can be said that the present invention is suitable for the present invention because the discrimination is easy.

On the other hand, in the case of data such as the main information recorded in the first area, complicated modulation and other signal processing are performed, and it is theoretically possible to determine the arrangement direction of the data. However, it cannot be easily carried out and is not suitable for the purpose of the present invention. Moreover, as described above, it becomes more difficult to perform surface discrimination or layer discrimination during the acceleration period before the spindle motor reaches the predetermined rotation speed, and in the non-operating state of the tracking control system. Therefore, these are not included in the category of the "data pattern that enables easy discrimination of the data array direction" described in the present invention.

However, the data pattern formed in the second region 3B is not limited to the one in which the period is sequentially increased or decreased, and any data pattern can be used as long as the data can be discriminated. If a simple modulation is performed and the array direction of the data can be easily discriminated even when the tracking control is inactive, it is used as a data pattern formed in the second area.

As the data pattern, it is preferable that the data pattern can be discriminated even when the tracking control is inactive. Especially when reproducing the back side, there is a problem that tracking control becomes unstable unless the polarity of the traverse control system that moves the optical head is reversed because the spiral direction is reversed. It is preferable to use a data pattern that enables surface discrimination even when the control is inactive. In order to realize this, it is preferable that the cycle of the data pattern (the cycle TD1 described in the embodiment) is short. Specifically, it is preferable to set 1/40 or less for one track (one round of the optical disc). It has been experimentally confirmed that when the time is shorter than 1/40 or less, the data can be stably reproduced even when the tracking control is in the non-operating state. Therefore, the period TD1 of this data pattern is shorter than the recording unit of the second recording area described with reference to FIG.

The optical recording / reproducing device described in the present invention includes all devices such as a reproduction-only device, a device for performing only a recording operation, and a device for performing both recording and reproduction. Furthermore, the label used in the present invention is not limited to the printing as described in the embodiment, and paper or a thin plastic sheet may be attached to the back surface B. Also in this case, the label is attached to the back surface B side while avoiding the second area on the information layer 3 which faces. Further, in the case where the printing layer (label layer) is provided on the back surface, the case where the user attaches the product after purchasing the product instead of forming the label surface by the disc manufacturer is also included in the application of the present invention.

Furthermore, the data pattern need only be able to be identified in its arrangement, so it is not necessary to provide the data pattern in the entire area of the second area, and it may be provided in part. This application is called pit art. Pit art is a visual technique that utilizes the difference in reflectance between the pit-provided portion where light is scattered by optical diffraction due to pits and the reflectance decreases, and the flatness where the pit is not formed increases. A recognizable image (figure or character) is drawn, and pit art can be formed in the second area of the information layer 3.

This pit art will be described with reference to FIG. FIG. 12 is a view of the optical disc 1 as viewed from the back surface B. A second region 3B having a data pattern for discriminating the data arrangement is provided in a region between the radii R ₁ and R ₂ on the disc radius. _A first area 3A in which main information is recorded is provided in an area between ₂ and R ₃ . Radius R ₁ , R ₂ , R ₃ ,
R ₄ is the same as that described with reference to FIG. 1, and a description thereof will be omitted. Further, the label layer is provided so as to substantially avoid the region between the radii R ₁ and R ₂ .

In FIG. 12, pits having a data pattern capable of discriminating the data arrangement are formed in the area between the radii R ₁ and R ₂ , but a flat surface having no pits is also formed in a part thereof. You can create and draw an image. In FIG. 12, “MATSU” is displayed in the second area on the information layer 3.
The character string "SHITA DVD" is drawn. As shown in an enlarged scale, the character string is drawn on a flat portion 81 having no pits, and the surrounding portion is a pit portion 83 composed of pits 82. Therefore, Since the character string portion 81 has a high reflectance, the character string can be visually recognized by the reflectance difference.

In addition, in the usual optical recording / reproducing apparatus, since the light beam is emitted from below as shown in FIG. 1, the user inserts the apparatus into the apparatus with the front surface A facing downward and the back surface B facing upward. To do. For this reason, it is desirable that the image (characters or figures) drawn by the pit art should be visually recognized as normal when the optical disk maker aims when viewed from the back surface B, and inverted when viewed from the front surface A. Formed to be visible.

By drawing this pit art, an area where the data pattern cannot be read occurs. However, when the light beam is applied to the flat portion where the pit is not formed, the reproduction signal is not generated in the optical head, and the reproduction signal is generated only from the pit formation portion. For this reason, it is only necessary to provide a reproduction signal level discriminating means and open the gate to discriminate the data array only when it is discriminated that the reproduction signal is above a predetermined level.

By drawing this pit art, for example, the following effects can be obtained. Since you can draw the necessary information such as the recorded contents of the disc without printing the label,
It is possible to provide a cheap disc that omits the printing process. The synergistic effect with the label surface enables more effective display. It is possible to prevent the risk that a disc maker accidentally prints on another disc when printing a label.

Further, as the adhesive applied to the optical disk of the present invention, it is preferable that it is transparent and contains less foreign matters such as bubbles, but in the method called hot melt method, the adhesive layer becomes white due to the inclusion of bubbles, etc. It becomes difficult to transmit light. However, on the other hand, the hot melt method is a bonding method used for many optical disks such as an optical disk called a laser disk having a diameter of 30 cm and an analog moving image recorded on one side for one hour, and is a part of existing equipment. Since it can be used, there is an advantage that there is no need to introduce new equipment. In the case of providing the adhesive layer by the hot melt method, another information layer is formed between the second transparent substrate and the adhesive layer, and the information layer has a radius R ₁ and R ₂ in an area between them.
An area is formed in which the data pattern formed in the second area of the information layer 3 provided on the first transparent substrate 2 has a reverse data array and the track spiral direction is also reversed.

When the optical disk is inserted, the optical head is moved to stop it by a mechanical stop mechanism or detect the position with a position sensor to stop it, thereby forming an optical spot at a position between the radii R ₁ and R _2. Is desirable. It is desirable that the range between the radii R ₂ and R ₁ be larger than the sum of the allowable value of the stop accuracy of the mechanical stop mechanism or the detection accuracy of the position sensor and the eccentricity of the optical disk. Therefore, it is desirable that these precisions be 0.3 mm or more in consideration of mass production of products. In addition, the second region is preferably formed on the inside of the first region because it is desirable that the second region is formed in a small surface and in the widest possible area on the radius. Also, the second area is desired to be as small as possible. From both of the above viewpoints, a suitable value for the range of the second region is about 0.3 to 2 mm.

[0070]

As described above, the optical information reproducing medium of the present invention has the information layer between the transparent substrates having substantially the same thickness, so that the second area for surface discrimination is formed on the surface,
It is possible to reproduce from both sides of the back side, and the reproduced side can be confirmed directly from the reproduced data. Therefore, this optical information reproducing medium can perform highly reliable surface discrimination.

Further, in the optical disc of the present invention, since the label area is provided while avoiding the second area substantially, it is easy to visually identify the front and back sides and the risk of erroneous insertion is reduced. Further, since the reproducing surface can be directly confirmed from the reproduced data, it is possible to provide an optical information reproducing medium capable of highly reliable surface discrimination.

The optical recording / reproducing apparatus according to the present invention can easily perform highly reliable surface determination by using the above-mentioned optical disk.

[Brief description of the drawings]

FIG. 1 is a sectional view of an optical information recording medium according to an embodiment of the present invention.

FIG. 2 is a plan view of the information layer viewed from the light beam irradiation surface side in the state of FIG.

3 is a cross-sectional view showing a state in which the optical information recording medium of FIG. 1 is erroneously inserted into the device and a back surface B is irradiated with a light beam.

FIG. 4 is a plan view of the information layer viewed from the light beam irradiation surface side in the state of FIG.

5 is a timing chart when the second area of the information layer of the optical information recording medium of FIG. 1 is reproduced from the surface A. FIG.

FIG. 6 is a timing chart when the second area of the information layer of the optical information recording medium of FIG. 1 is reproduced from the back surface B.

FIG. 7 is a block diagram of an optical recording / reproducing device.

FIG. 8 is a block diagram of a surface discriminating apparatus for discriminating surfaces of an optical information recording medium.

FIG. 9 is a waveform diagram of each part of the surface determination device when the second area of the information layer of the optical information recording medium is reproduced from the surface A.

FIG. 10 is a waveform diagram of each part of the surface determination device when the second area of the information layer of the optical information recording medium is reproduced from the back surface B.

11 is a second information layer of the optical information recording medium of FIG.
The partial top view of the modification embodiment of a field.

FIG. 12 is a partial plan view of the pit art in the second area according to the present invention.

[Explanation of symbols]

 1 Optical Disc 2 First Transparent Substrate 3 Information Layer 3A First Area 3B Second Area 4 Adhesive Layer 5 Second Transparent Substrate 6 Printing Layer 8, 8'Light Spot 13 Optical Head 18 Surface Discriminating Device 32 Period Counter 36 Digital Comparison 39 Up / down counter L1, L3 Pit length L2, L4 Pit interval TD1 One cycle of data pattern

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location G11B 20/12 9295-5D G11B 20/12

Claims (15)

[Claims] 1. A first transparent substrate, a second transparent substrate, and a first transparent substrate.
And an information layer provided between the second transparent substrate and
The first transparent substrate is provided with pits representing information on the side in contact with the information layer, and the information layer has a first area for recording main information and a data pattern for discriminating the arrangement direction of data. An optical information recording medium comprising two areas. 2. An imaged label layer is further provided on the second transparent substrate, the label layer being provided substantially avoiding the second region of the facing information layer. The optical information recording medium according to claim 1. 3. The data pattern formed in the second area of the information layer is recorded by a data modulation method different from that of the main information recorded in the first area of the information layer. 1. The optical information recording medium according to 1 or 2. 4. The data pattern formed in the second region of the information layer has at least three different lengths, and the lengths increase or decrease sequentially. Or the optical information recording medium described in 3 above. 5. The length of the data pattern recorded in the second area of the information layer is 1/4 of the length of the track on the information layer.
It is 0 or less, Claim 1, 2, 3 or 4 characterized by the above-mentioned.
The optical information recording medium described in the above. 6. The data pattern formed in the second area of the information layer is repeatedly formed a plurality of times in the second area of the information layer. The optical information recording medium described. 7. The data pattern recorded in the second area of the information layer has a track pitch and a recording density different from those of the main information recorded in the first area. 3. The optical information recording medium described in 3, 4, 5 or 6. 8. The information layer and the second transparent substrate are adhered by an adhesive layer, and the thickness of the adhesive layer is 100 μm or less, 1, 2, 3, 4, 5, 6 or 7. The optical information recording medium described in 7. 9. The information layer has a thickness of 5 to 200 nm, as claimed in claim 1, 2, 3, 4, 5, 6, 7, or 8.
The optical information recording medium described in the above. 10. An optical information recording medium for an optical recording / reproducing apparatus for recording, reproducing or erasing data by using an optical head having a focusing optical system with a numerical aperture of about NA _1. provided from the radius R ₁ in the region of _{R 2 (R 2> R 1} ), the label layer at least from the radius (R ₁ -δ ₁₎ (R
₂ + δ ₁ ) (where the thickness of the second transparent substrate is t ₂ , the refractive index is n _2, and the focusing angle of the light beam on the second transparent substrate is θ ₂ = sin ⁻¹ (NA ₁ / N ₂ ) and the radius of the light beam on the back surface is represented by δ ₁ = t ₂ · tan (θ ₂ )).
8. The optical information recording medium according to 8 or 9. 11. The second area of the information layer is composed of an area for forming a data pattern and an area having a reflectance different from that of the area for forming the data pattern, and an image visible to the naked eye due to the difference in reflectance. The optical information recording medium according to claim 2, 3, 4, 5, 6, 7, 8, 9 or 10, wherein the optical information recording medium is formed. 12. The region having a reflectance different from that of the region for forming the data pattern is provided so that an image can be normally observed from the back surface.
3, 4, 5, 6, 7, 8, 9, 10 or 11, the optical information recording medium. 13. A first transparent substrate, a second transparent substrate, and an information layer provided between the first and second transparent substrates, wherein the first transparent substrate has information on the side in contact with the information layer. The information layer is provided with pits representing the information from the optical information recording medium including the first area for recording the main information and the second area for forming the data pattern for discriminating the data arrangement direction. In a device for optically reproducing, a drive device for rotating an optical information recording medium, an optical head for reading a signal formed in an information layer of the optical information recording medium, and an optical head for the second area of the information layer. 2. An optical recording / reproducing apparatus comprising: a transfer unit that transfers the data in the second area; and a determination unit that determines the arrangement direction of the data of the data pattern from the signal received from the optical head in the second area. 14. The optical recording / reproducing apparatus according to claim 13, wherein the discriminating means includes first counter means for counting the length of a signal in the data pattern received from the optical head, and Comparing means for comparing the length of the first signal counted by the first counter means with the length of the second signal next to the first signal; and the result of the comparison received from the comparing means for data An optical recording / reproducing apparatus comprising: second counter means for detecting a continuous increase or decrease in the length of a signal in a pattern. 15. The optical recording / reproducing apparatus according to claim 13 or 14, further comprising alarm means for giving an alarm to a user when the determining means determines erroneous insertion of an optical recording / reproducing medium. An optical recording / reproducing apparatus comprising: