JP2006120199A - Information reproducing method and identification method of optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an identification method by which a lead time from the discrimination of an optical recording medium to the start of the recording/reproducing of user information or the like can be shortened and an optical disk can be discriminated at a low cost. <P>SOLUTION: In a method for reproducing information including at least identification information recorded in the optical recording medium, a first optical recording medium which is irradiated with a first light beam having a prescribed spot size subjected to information reproduction is irradiated with a second light beam having a spot size smaller than that of the first light beam, the identification information of the first optical recording medium is reproduced based on the second light beam from the first optical recording medium. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an information reproducing method for an optical recording medium, and more specifically, information including at least identification information recorded on the optical recording medium is reproduced by an information recording / reproducing apparatus including a plurality of laser light sources and / or optical systems. Regarding the method.

  Up to now, optical information recording media (optical discs) have attracted attention as information recording media that can record a large amount of data at high density and can be quickly recorded and reproduced in accordance with the development of multimedia. In fact, as seen in the recent spread of compact discs (CDs) and DVDs, optical discs have been established as very common recording media. As a recording / reproducing apparatus for these optical disks, a recording / reproducing apparatus corresponding to a reproduction-only type disk capable of only reproducing information by stamping and recording information on the disk at the time of manufacturing the disk, such as a CD or a laser disk. , A recording / reproducing apparatus corresponding to a write-once disc that can be recorded only once, such as a CD-R, and data can be rewritten and erased many times using a magneto-optical recording method or a phase change recording method. A recording / reproducing apparatus corresponding to a rewritable disc is known.

  Data recording / reproduction on an optical disc is performed by irradiating a recording surface of the optical disc with a light spot obtained by narrowing the laser beam to the diffraction limit using an objective lens. The diameter of the light spot is about (λ / NA), where λ is the wavelength of the laser beam and NA is the numerical aperture of the objective lens. In general, in order to increase the capacity of an optical disk, it is effective to use a light beam having a smaller spot diameter when recording and reproducing information. Therefore, in order to respond to the recent demand for an increase in the capacity of optical disks, the optical disk products have been increased in density, and recording / reproducing apparatuses for recording / reproducing information on these optical disks have adopted shorter wavelength lasers. Development of technology for reducing the diameter of the spot focused on the recording surface of the optical disc by using an objective lens having a larger numerical aperture (NA) is being promoted. For example, specifically, the wavelength of the laser light source is shortened to 650 nm or 635 nm, or the numerical aperture (NA) of the objective lens is set to 0.6 to increase the NA. In the next generation optical recording, further shortening of wavelength and higher NA have been proposed in order to further increase the density of information. For example, the wavelength of the laser light source is set to about 400 nm and the aperture of the objective lens is increased. It has been proposed that the number NA is 0.6 or more.

  The flow of increasing the density of information in an optical disc will be described more specifically. Conventionally, a CD-R / RW has a laser wavelength of 780 nm and a numerical aperture of 0.45, whereas the DVD-R / RW In RW / RAM, the laser wavelength was 650 nm and the numerical aperture was set to around 0.6. On the other hand, at present, the performance of optical disks has been improved to meet further market demands, and the development of large-capacity optical disks using shorter wavelength blue lasers has been accelerated. The laser wavelength is 405 nm, the numerical aperture is The standard of the optical disk corresponding to the optical head whose is 0.65-0.85 is examined.

  By the way, when various types of optical discs having different standards (types) are commercialized as described above, the optical discs between various driving devices (recording and / or reproducing devices, hereinafter also referred to as drives) for driving the optical discs. Compatibility is an important issue. If an optical disc product of a new standard cannot be installed in an existing drive and an existing optical disc cannot be installed in a new drive, that is, if the compatibility of the optical disc is cut off, it is necessary to consider the issue regarding the compatibility of the optical disc. Absent. However, from the user's point of view, it is desirable that information can be recorded and reproduced even when an existing optical disk is mounted with a new drive. Therefore, it is necessary for the drive to have a structure that can be driven even with optical discs of different standards. For example, the drive needs to have a function of discriminating optical discs with different standards.

  Currently, so-called multi-drives have been developed that are equipped with a plurality of laser light sources and / or optical systems having different wavelengths in a single drive and are compatible with optical disks of different standards. In the multi-drive, when an optical disc is inserted into the drive, the type of the inserted optical disc is determined, and information is recorded and reproduced by a laser light source and an optical system corresponding to the optical disc. For discriminating the type of the optical disc, generally, discriminating the optical disc is performed by reproducing the identification information recorded on the optical disc. However, when optical discs of different standards use substantially the same optical system, it is possible to discriminate the optical disc by reproducing the identification information recorded on the optical disc using the same optical system.

  Conventionally, as a method for discriminating the type of an optical disc, after disc type is discriminated and set based on the number of S-curves included in the focus error signal and the amplitude value, the signal is actually read and the result is A method of changing the setting content based on the proposed method has been proposed (see, for example, Patent Document 1). Further, the substrate thickness of the optical disc is identified by the substrate thickness correcting means that adjusts the focal length of the irradiation light to the optical recording medium according to the detection result of the substrate thickness sensor that detects the thickness of the optical recording medium. A method for discriminating the type has been conventionally proposed (see, for example, Patent Document 2). Further, a method of discriminating whether a mounted disc is a CD or a DVD by detecting a difference in track density by moving the pickup a certain distance in the direction across the track and counting the number of tracks. Has also been proposed (see, for example, Patent Document 3).

JP 2000-149392 A (pages 3-6, FIGS. 1-7) JP-A-10-334575 (page 3-4, FIG. 1-6) Japanese Patent Laid-Open No. 11-213529 (page 3, FIG. 3)

  When discriminating means such as a substrate thickness sensor as described in Patent Document 2 is used to identify optical discs with different standards, it is necessary to provide the discriminating means separately from the optical head. Therefore, such a method causes a problem that the cost of the drive increases. Further, in such a method, since the optical head is driven after the discriminating means discriminates the optical disc, there arises a problem that the lead time until the information recording / reproducing operation becomes possible becomes long.

  Further, when the type of the optical disc is discriminated by directly accessing the optical head without providing the special discriminating means as described above, the optical disc mounted on the drive always generates a light beam having a large spot diameter. Assuming that the optical disk corresponds to the head, it is necessary to perform an optical disk discrimination operation using a light beam having a large spot diameter. This is because when an optical disc that supports a light beam having a large spot diameter and a recordable optical disc is loaded in the drive, the optical head generates an optical beam having a smaller spot diameter than the optical beam corresponding to the optical disc. As the spot diameter of the light beam becomes smaller, the energy density of the light beam increases, which may damage the recording layer of the optical disc, erroneously erase recorded information, or make recording impossible. . For example, when a recordable optical disc (DVD-R, CD-R, etc.) compatible with a red laser is inserted into a drive for an HD DVD (AOD: Advanced Optical Disc) equipped with a blue laser, the blue laser is irradiated. When discriminating the type of optical disc, the energy density of the blue laser beam is larger than that of the red laser beam. At that time, the data recorded on the optical disc compatible with the red laser is destroyed or the optical disc is not recorded. There is a risk of damaging the area.

  In order to solve the above-described problems, in the conventional multi-drive, when the optical disk is mounted in the drive, the type of the optical disk mounted is determined using the light beam having the larger spot diameter. As a result of the determination, if the mounted optical disk is an optical disk corresponding to the light beam having the larger spot diameter, the access is continued without switching the optical head, and user information and the like are recorded and / or reproduced. Do. On the other hand, if the mounted optical disk is an optical disk corresponding to the light beam having the smaller spot diameter, the optical head is switched to the optical head having the smaller spot diameter to record and / or reproduce user information and the like. .

  More specifically, for example, in the case of a multi-drive capable of supporting both an optical disk DVD-R compatible with a red laser and an optical disk AOD compatible with a blue laser, the red laser is first used regardless of which optical disk is loaded in the drive. To determine the type of optical disc. When a determination result that the optical disk is a DVD-R is obtained, information is recorded and / or reproduced by continuing access with an optical head mounted with a red laser as it is. On the other hand, when a determination result that the optical disk is AOD is obtained, information is recorded and / or reproduced by switching the optical head from the optical head equipped with the red laser to the optical head equipped with the blue laser. As described above, when an optical disc is mounted on a drive and a discrimination operation is performed by irradiating a blue laser with high energy density from the beginning, the mounted optical disc is a recordable red laser such as a DVD-R. This is because the information recorded on the recordable optical disc corresponding to the red laser may be accidentally erased when the optical disc is compatible.

  In the future, as the need for optical disks with larger capacity increases, the mainstream of optical disks to be used is likely to shift from optical disks DVD compatible with low-capacity red lasers to optical disks AOD compatible with large-capacity blue lasers. In such a situation, the frequency of use of the optical disk AOD corresponding to the large-capacity blue laser increases. Therefore, when the optical disk is driven by a conventional drive, the optical disk is discriminated by an optical head equipped with a red laser as described above. Then, the frequency of the operation of switching to an optical head equipped with a blue laser increases thereafter. As a result, there arises a problem that it takes a long time from the determination of the optical disk to the start of recording / reproduction of user information and the like. In addition, in a drive having only an optical head equipped with a blue laser, the optical disk discriminating operation is always performed by irradiating the optical disc compatible with the red laser with the blue laser. Problems such as accidentally erasing information recorded on a possible optical disk cannot be avoided, and may become a more serious problem.

  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is an optical disc compatible with a short wavelength laser (for example, a blue laser) in a drive capable of recording and / or reproducing optical discs of different standards. Information that shortens the processing time of a series of operations from discriminating an optical disc to recording / reproducing user information and the like and discriminating the optical disc at low cost even when the frequency of use (for example, AOD) increases. A reproduction method and an identification method are provided.

  According to the first aspect of the present invention, there is provided a method for reproducing information recorded on an optical recording medium including at least identification information, wherein information reproduction is performed by irradiating a first light beam having a predetermined spot size. The first optical recording medium is irradiated with a second light beam having a smaller spot size than the first light beam, and the identification information of the first optical recording medium is based on the second light beam from the first optical recording medium. For reproducing information from an optical recording medium.

In the information reproducing method of the optical recording medium of the present invention, the wavelength of the first light beam when reproducing the information by irradiating the first optical recording medium with the first light beam is λ ₁ , the numerical aperture of the objective lens is NA ₁ and The linear velocity of the first optical recording medium is V ₁ , the maximum reproduction power of the first light beam under the reproduction conditions is Pr _1max, and the first optical recording medium is irradiated with the second light beam to produce the first light. When reproducing the identification information of the recording medium, the wavelength of the second light beam is λ ₂ , the numerical aperture of the objective lens is NA ₂ , the linear velocity of the first optical recording medium is V _2, and the reproduction power of the second light beam is Pr ₂
Pr ₂ ≦ {(λ ₂ NA ₁ ) / (λ ₁ NA ₂ )} ² Pr _1max (V ₂ / V ₁ ) ^1/2
It is preferable to set the reproduction power Pr ₂ of the second light beam so that the above relationship is satisfied.

In the information reproducing method of the optical recording medium of the present invention, the wavelength of the first light beam when reproducing the information by irradiating the first optical recording medium with the first light beam is λ ₁ , the numerical aperture of the objective lens is NA ₁ and The linear velocity of the first optical recording medium is V ₁ , the maximum reproduction power of the first light beam under the reproduction conditions is Pr _1max, and the first optical recording medium is irradiated with the second light beam to produce the first light. When reproducing the identification information of the recording medium, the wavelength of the second light beam is λ ₂ , the numerical aperture of the objective lens is NA ₂ , the linear velocity of the first optical recording medium is V _2, and the reproduction power of the second light beam is Pr ₂
V ₂ ≧ {(λ ₁ NA ₂ ) / (λ ₂ NA ₁ )} ⁴ (Pr ₂ / Pr _1max ) ² V ₁
It is preferable to set the linear velocity V ₂ of the first optical recording medium so that the above relationship is satisfied.

In the information reproducing method of the optical recording medium of the present invention, the wavelength of the first light beam when the first optical recording medium is irradiated with the first light beam to reproduce the information is λ ₁ and the numerical aperture of the objective lens is NA _1. The maximum reproduction power of the first light beam under the reproduction condition is Pr _1max, and the second light beam is reproduced when the first optical recording medium is irradiated with the second optical beam to reproduce the identification information of the first optical recording medium. The spot at the focal point of the wavelength of the light beam λ ₂ , the numerical aperture of the objective lens NA ₂ , the reproduction power of the second light beam Pr _2, and the spot area of the second light beam irradiated to the first optical recording medium When the enlargement ratio for the area is α,
α ≧ (Pr ₂ / Pr _1max ) {(λ ₁ NA ₂ ) / (λ ₂ NA ₁ )} ²
It is preferable to set the enlargement ratio α of the spot area of the second light beam so that the above relationship is satisfied.

  As described above, when the optical disk to be used mainly in the future becomes a large capacity optical disk such as AOD, the optical disk is discriminated by the optical head equipped with the red laser, and then switched to the optical head equipped with the blue laser. If information is recorded / reproduced, the processing time from discriminating the optical disk to the start of recording / reproduction of user information and the like becomes longer. In order to solve this problem, if the optical disc can be discriminated with a blue laser, the frequency of switching the optical head when switching from the disc discriminating operation to the recording / reproducing operation of user information, etc. is reduced. Thereafter, the time until the recording / reproducing operation is started can be shortened on average. However, as described above, the laser beam of the blue laser has a high energy density because the spot diameter is narrowed down compared to the laser beam of the red laser. Therefore, if the optical disk loaded in the drive is a recordable optical disk such as a CD-R or DVD-R, for example, when the optical disk is discriminated with a blue laser, it is recorded on the CD-R or DVD-R. Information may be damaged or a defect may be created in an unrecorded area of the optical disk.

  In order to solve the above problems, the information reproducing method of the optical recording medium of the present invention is mounted on the information recording / reproducing apparatus using the second light beam having a smaller spot diameter than the first light beam having the predetermined spot diameter. When discriminating the optical recording medium, even if the mounted optical recording medium is the first optical recording medium corresponding to the first light beam, the reproduction condition that the information recorded on the first optical recording medium is not destroyed Then, the second optical beam is irradiated onto the first optical recording medium to reproduce the identification information of the first optical recording medium. In other words, when the mounted optical recording medium is identified by irradiating the mounted optical recording medium with a second light beam having a smaller spot diameter, information recorded on the mounted optical recording medium is not destroyed. The identification information of the optical recording medium loaded under conditions is reproduced to determine the type of the optical recording medium loaded. More specifically, in the identification method of the present invention, for example, in an information recording / reproducing apparatus compatible with DVD and AOD, an optical head equipped with a blue laser is used as the type of optical disk mounted on the information recording / reproducing apparatus. To determine. At this time, even if the mounted optical disk is a DVD, the identification information recorded on the DVD is reproduced by irradiating the DVD with blue laser light under the reproduction conditions such that the information recorded on the DVD is not destroyed.

  The “optical head” in this specification includes an optical member such as a laser light source and a lens, and the optical member such as a lens may be common among a plurality of optical heads, or provided separately. May be. When an optical member such as a lens is common among a plurality of optical heads, the spot size of the light beam can be switched by switching the laser light source. In the present invention, the identification information of the optical recording medium is preferably recorded on a BCA (Burst Cutting Area).

The procedure for reproducing the identification information of the optical recording medium in the present invention is as follows. First, the maximum reproduction power Pr _1max of the first light beam that can be irradiated when information is reproduced from the first optical recording medium using the first light beam having a predetermined spot size (the first light beam that does not destroy the recording data). Of the optical recording medium mounted on the information recording / reproducing apparatus by irradiating the optical recording medium mounted on the information recording / reproducing apparatus with a second light beam having a smaller spot size than the first light beam. Set the playback conditions for playing. At this time, the energy density when the first optical recording medium is irradiated with the first light beam having the maximum reproducing power Pr _1max as the energy density of the second light beam having the reproducing power Pr ₂ irradiated to the mounted optical recording medium. Is set so that the mounted optical recording medium is discriminated. Next, the optical recording medium mounted with the second light beam is irradiated under the set reproduction conditions. Next, the identification information of the mounted optical recording medium is reproduced based on the second light beam (reflected light or transmitted light from the optical recording medium) from the mounted optical recording medium, and the type of the optical recording medium is determined. .

Note that the maximum reproduction power Pr _1max of the first light beam that can be irradiated when information is reproduced from the first optical recording medium is measured in advance before determining the type of the optical recording medium attached to the information recording / reproducing apparatus. It is preferable to keep it. Here, a method for measuring the maximum reproduction power Pr _1max of the first light beam that can be irradiated when reproducing information on the first optical recording medium will be specifically described. First, a first optical recording medium that records and reproduces user information and the like with a first optical head (hereinafter also referred to as a λ ₁ optical head) equipped with a laser of wavelength λ ₁ , that is, recording corresponding to the λ ₁ optical head is possible. A first optical recording medium is continuously irradiated with a laser beam having a predetermined laser power Pe _{1 on} a recordable area of the first optical recording medium using a λ ₁ optical head. Next, using the λ ₁ optical head, a laser beam having a predetermined reproduction power (reproduction power used when reproducing user information or the like) is irradiated to the position where the laser beam with the laser power Pe ₁ of the first optical recording medium is irradiated. Then, the reproduction signal is detected. The above measurement is repeated while changing the laser power Pe ₁ . An example of the characteristic of the change amount of the reproduction signal output with respect to the laser power Pe ₁ obtained by this measurement is shown in FIG.

When the measurement as described above is performed, as apparent from FIG. 1, when the laser power Pe ₁ becomes larger than a certain value (Pr _{1max in} FIG. 1), the reproduction signal output is changed, and the laser power Pe ₁ is further changed. If it is increased, a characteristic that the amount of change in the reproduction signal output is saturated can be obtained. The reason why the reproduction signal output changes when the laser power Pe ₁ is set larger than the rise value of the reproduction signal output is that the reproduction signal output changes due to a change corresponding to the “recording” state in the recording layer of the optical disc. It is. That is, FIG. 1 shows that when a laser beam with a laser power larger than the laser power Pr _{1max at which the} amount of change in the reproduction signal output rises, the recording layer is altered and the information recorded on the recording layer may be destroyed. It shows that there is. Therefore, the maximum reproduction power of the first light beam that can be emitted when reproducing information on the first optical recording medium is the output Pr _{1max in} FIG. Usually, in the first optical recording medium showing a characteristic as shown in FIG 1, the reproduction power Pr ₁ of the laser beam irradiated when information reproduction laser power rises variation of the reproduced signal output, i.e., the maximum reproduction power Pr _1max less Is set to be By setting the reproduction power in this way, it is possible to reproduce information without destroying data recorded on the first optical recording medium or damaging an unrecorded area of the first optical recording medium. Become.

In addition, when the identification information of the mounted optical recording medium is reproduced by irradiating the optical recording medium mounted on the information recording / reproducing apparatus with a second light beam having a smaller spot size than the first light beam, the mounted light is reproduced. The energy density of the second light beam with the reproduction power Pr ₂ applied to the recording medium is adjusted so as not to exceed the energy density when the first light beam with the maximum reproduction power Pr _1max is applied to the first optical recording medium. The following three methods are conceivable as methods.
[1] Setting a low reproducing power Pr ₂ of the second light beam irradiated onto the loaded optical recording medium.
[2] Increase the linear velocity of the loaded optical recording medium.
[3] Defocus the second light beam applied to the mounted optical recording medium.
In any method, when reproducing the identification information of the mounted optical recording medium, the energy density of the second light beam applied to the mounted optical recording medium is recorded on the mounted optical recording medium. It can be made small so as not to destroy the data. Hereinafter, the methods [1] to [3] will be described in detail.

[1] Method of Setting Reproduction Power Pr ₂ of Second Light Beam Low Here, identification information of the first optical recording medium corresponding to the first optical head (λ ₁ optical head) is irradiated from the first optical head. consider the case of reproducing in that the first light beam of a small spot diameter than the spot diameter of light beam second optical head capable of generating a (lambda ₂ light head). Note that the wavelength of the first light beam emitted from the λ ₁ optical head is λ ₁ , the numerical aperture of the lens is NA _1, and the linear velocity when information is reproduced from the first optical recording medium by the λ ₁ optical head is V ₁ (the linear velocity when the experiment of FIG. 1 is performed) and the maximum reproduction power that can be irradiated with the first light beam under the reproduction condition is Pr _1max . However, it is _assumed that Pr _1max is obtained in advance by measuring the maximum reproduction power of the first light beam when information is reproduced from the first optical recording medium with the λ ₁ optical head. Further, the wavelength of the second light beam emitted from the λ ₂ optical head is λ ₂ and the numerical aperture of the lens is NA _2, and the first light when the identification information of the first optical recording medium is reproduced by the λ ₂ optical head. The linear velocity of the recording medium is V ₂ and the reproduction power of the second light beam is Pr ₂ .

In the method [1], when the identification information of the first optical recording medium corresponding to the λ ₁ optical head is reproduced by the λ ₂ optical head,
Pr ₂ ≦ {(λ ₂ NA ₁ ) / (λ ₁ NA ₂ )} ² Pr _1max (V ₂ / V ₁ ) ^1/2 (1)
The reproduction power Pr ₂ of the second light beam irradiated from the λ ₂ optical head to the first optical recording medium is set so that the above relationship is satisfied. In general, the energy density of the light beam applied to the optical recording medium is determined by the spot size of the light beam, the irradiation power, and the linear velocity of the optical recording medium. The above equation (1) indicates that the spot area of the second light beam with the reproduction power Pr ₂ irradiated from the λ ₂ optical head and the spot area of the first light beam with the maximum reproduction power Pr _1max irradiated from the λ ₁ optical head. And the linear velocity V ₂ when reproducing the identification information of the first optical recording medium by the λ ₂ optical head and the linear velocity V ₁ when reproducing the information of the first optical recording medium by the λ ₁ optical head. Calculated from the ratio.

Equation (1) of the relationship is so set the reproduction power Pr ₂ of the second light beam from the lambda ₂ light head met, lambda ₂ of the second light beam of reproducing power Pr ₂ from the optical head first optical recording The energy density when the medium is irradiated is a value equal to or lower than the energy density when the first optical recording medium is irradiated with the first light beam having the maximum reproduction power Pr _1max by the λ ₁ optical head. Therefore, when reproducing the identification information of the first optical recording medium using the λ ₂ optical head, if the above method [1] is used, the information recorded on the first recording medium is not destroyed or has not been destroyed. The identification information of the first optical recording medium can be reproduced without damaging the recording area.

[2] Method of increasing the linear velocity of the mounted optical recording medium When the linear velocity of the optical recording medium at the time of reproduction is changed, the irradiation time of the light beam applied to a predetermined area of the optical recording medium changes. The irradiation amount per unit time of the light beam applied to the optical recording medium can be changed. The higher the linear velocity of the optical recording medium during playback, the shorter the irradiation time of the light beam that irradiates a predetermined area of the optical recording medium. Can be small. Therefore, by increasing the linear velocity of the optical recording medium during reproduction, the energy density of the light beam applied to the optical recording medium can be reduced. Here, lambda a _first identification information of the first optical recording medium corresponding to the optical head, with a small second light beam capable of generating lambda ₂ light head spot diameter than the first light beam emitted from the lambda ₁ light head Consider the case of playing.

In method [2], when reproducing the identification information of the first optical recording medium using the lambda ₂ light head, reduce the energy density of the second light beam emitted from the lambda ₂ light head to the first optical recording medium to increase the linear velocity V ₂ of the first optical recording medium. Specifically, when reproducing the identification information of the first optical recording medium using the λ ₂ optical head, from the above equation (1),
V ₂ ≧ {(λ ₁ NA ₂ ) / (λ ₂ NA ₁ )} ⁴ (Pr ₂ / Pr _1max ) ² V ₁ (2)
So that the linear velocity V ₂ of the first optical recording medium is increased. In the method [2], the reproduction power Pr ₂ of the second light beam emitted from the λ ₂ optical head is a predetermined value, for example, an optical recording medium (second optical recording medium) corresponding to the λ ₂ optical head. Can be set to a value such as reproduction power used when information is reproduced by the λ ₂ optical head.

Even when the linear velocity V ₂ of the first optical recording medium is set so that the relationship of the above expression (2) is satisfied, the first optical recording medium is irradiated with the second light beam of the reproduction power Pr ₂ from the λ ₂ optical head. In this case, the energy density becomes a value equal to or lower than the energy density when the first optical recording medium is irradiated with the first light beam having the maximum reproduction power Pr _1max with the λ ₁ optical head. Therefore, when the identification information of the first optical recording medium is reproduced using the λ ₂ optical head, the information recorded on the first recording medium can be destroyed even if the method [2] as described above is used. The identification information of the first optical recording medium can be reproduced without damaging the unrecorded area.

As described above, when the identification information is reproduced from the first optical recording medium using the λ ₂ optical head, the linear velocity V ₂ of the first optical recording medium is set so that the relationship of the above expression (2) is satisfied. However, the present invention is not limited to this. For example, instead of the maximum reproduction power Pr _1max of the first light beam when information is reproduced from the first optical recording medium with the λ ₁ optical head in the above formula (2), the first light is usually _{output with} the λ ₁ optical head. Using the reproduction power Pr ₁ of the first light beam used when reproducing information from the recording medium,
V ₂ ≧ {(λ ₁ NA ₂ ) / (λ ₂ NA ₁ )} ⁴ (Pr ₂ / Pr ₁ ) ² V ₁ (2 ′)
Like the relationship is satisfied, it may be adjusted linear velocity V ₂ of the first optical recording medium. The range of the above formula (2) is a range that theoretically does not cause data destruction, and the range of the formula (2 ′) is included in the range of the formula (2). When the equation (2 ′) is used, it is not necessary to actually measure the maximum reproduction power Pr _1max of the first light beam, which is a simple setting method. However, when the reproduction condition at the time of discriminating the optical recording medium is set using the equation (2 ′), the settable range becomes narrower than the range obtained by the equation (2). Therefore, it is preferable to select the formula (2) or the formula (2 ′) as appropriate depending on the situation.

[3] Method of defocusing the second light beam The energy density of the light beam applied to the optical recording medium is reduced by shifting (defocusing) the focal position of the light beam applied to the optical recording medium during reproduction. You can also When the light beam is defocused, the spot size of the light beam applied to the optical recording medium is increased, so that the energy density of the light beam can be reduced. Here, lambda ₁ the identification information of the first optical recording medium corresponding to the optical head, lambda ₁ capable of generating a second light beam of a small spot diameter than the spot diameter of the first light beam emitted from the optical head lambda ₂ Consider the case of reproducing with an optical head.

In method [3], when reproducing the identification information of the first optical recording medium using the lambda ₂ light head, the energy density of the second light beam emitted from the lambda ₂ light head to the first optical recording medium, lambda ₁ of the first light beam of the maximum reproduction power Pr _1max in the optical head so that the following values energy density when irradiated with the first optical recording medium, de second light beam emitted from the lambda ₂ light head Focus to widen the spot size of the second light beam. Specifically, when the enlargement ratio of the spot area of the second light beam irradiated to the first optical recording medium from the λ ₂ optical head with respect to the spot area at the time of focusing is α,
Pr ₂ / [απ {λ ₂ / (2NA ₂ )} ² ] ≦ Pr _1max / [π {λ ₁ / (2NA ₁ )} ² ]
That is,
α ≧ (Pr ₂ / Pr _1max ) {(λ ₁ NA ₂ ) / (λ ₂ NA ₁ )} ² (3)
In order to satisfy the above relationship, α is set as the enlargement ratio of the spot area of the second light beam irradiated from the λ ₂ optical head to the first optical recording medium, and the λ ₂ optical head changes to the first optical recording medium. The second light beam to be irradiated is defocused.

When reproducing the identification information of the first optical recording medium using the λ ₂ optical head, the second light beam emitted from the λ ₂ optical head is defocused so that the relationship of the above expression (3) is satisfied. When the spot size of the light beam is widened, the energy density when the first optical recording medium is irradiated with the second light beam with the reproduction power Pr ₂ from the λ ₂ optical head is the first density of the maximum reproduction power Pr _1max with the λ ₁ optical head. The value is equal to or lower than the energy density when the first optical recording medium is irradiated with one light beam. Therefore, when the identification information of the first optical recording medium is reproduced using the λ ₂ optical head, the information recorded on the first recording medium is destroyed even if the method [3] as described above is used. The identification information of the first optical recording medium can be reproduced without damaging the unrecorded area.

As described above, if the identification information of the first optical recording medium is reproduced using Pr ₂ , V ₂ and α set in the methods [1] to [3], the first optical recording medium is discriminated at the first time. Information recorded on the optical recording medium is not destroyed. On the other hand, the reproduction conditions set by the above-described methods [1] to [3] are the light beams that are applied to the second optical recording medium from the reproduction conditions that are set during normal reproduction with respect to the second optical recording medium. Therefore, even when reproducing the identification information of the second optical recording medium, the recorded information of the second optical recording medium is not destroyed. Therefore, even if the identification information of the mounted optical recording medium is reproduced under the setting conditions of any one of the methods [1] to [3], the recorded information is destroyed regardless of the type of the mounted optical recording medium. Thus, the type of the optical recording medium loaded can be identified.

Further, in the information reproducing method of the optical recording medium of the present invention, the maximum reproduction power Pr _2max of the second light beam that can be applied to the first optical recording medium is measured in _advance , and the second light beam is used for the first optical recording. It is also possible to set the reproduction power of the second light beam when reproducing the identification information of the first optical recording medium by irradiating the medium to the maximum reproduction power Pr _2max or less. As a specific method, the maximum reproduction power Pr _2max of the second light beam that can be applied to the first optical recording medium can be measured by a method similar to the method described in FIG. However, in this case, in the method described with reference to FIG. 1, the same experiment is performed by irradiating the first optical recording medium with the second light beam instead of the first light beam. As a result, the same characteristics as in FIG. 1 are obtained, and the maximum reproduction power Pr _2max of the second light beam that can be applied to the first optical recording medium is obtained by _setting the signal change point of the characteristics to Pr _2max. Can do.

In the information reproducing method of the optical recording medium of the present invention, the minimum value V _2min of the linear velocity V ₂ of the first optical recording medium that can reproduce information by irradiating the first optical recording medium with the second light beam is measured in advance. The linear velocity V ₂ of the first optical recording medium when the first optical recording medium is irradiated with the second light beam to reproduce the identification information of the first optical recording medium is set to the minimum value V _{2 min} or more. It is also possible.

In the information reproducing method of the optical recording medium of the present invention, the enlargement ratio α of the spot area of the second light beam that can be reproduced by irradiating the first optical recording medium in advance with respect to the spot area at the time of focusing. The minimum value α _min of the first optical recording medium is measured, and the second light beam is irradiated onto the first optical recording medium to reproduce the identification information of the first optical recording medium. It is also possible to set so as to be not less than the minimum value α _min .

  Further, in the information recording / reproducing apparatus capable of dealing with three or more types of optical recording media having different standards, the above method is also used when the type of the optical recording medium mounted by irradiating a light beam having a smaller spot diameter is discriminated. It is possible to reproduce the identification information of the optical recording medium loaded in the same manner. Specifically, it is preferable to reproduce the identification information of the optical recording medium loaded by the following method.

First, the optical recording medium A considered to have the highest mounting frequency is selected from a plurality of optical recording media (A, B, C,...) That can be mounted on the information recording / reproducing apparatus. However, the optical recording medium A is not an optical recording medium corresponding to the light beam having the maximum spot diameter among the plurality of optical recording media. In this case, each optical recording medium (B, C,...) Other than the optical recording medium A corresponds to the first optical recording medium described in the above method. Next, after selecting the optical recording medium A that is considered to be the most frequently mounted, the optical head a (second light beam irradiation) used for reproducing information from the optical recording medium A is performed according to the above methods [1] to [3]. The reproduction power Pr ₂ , the linear velocity V _2, or the spot enlargement ratio α when reproducing the identification information of the optical recording media B, C,... Is obtained for each optical recording medium.

Then, when adjusting the reproducing conditions for reproducing the identification information of the mounted optical recording medium using the optical head a at read power Pr ₂ were asked each optical recording medium B, C, ... in the reproduction the minimum value of the power Pr _2, the reproduction power Pr ₂ in reproducing the identification information of the mounted optical recording medium using the optical head a. Also, when adjusting the reproducing conditions for reproducing the identification information of the mounted optical recording medium using the optical head a at a linear velocity V ₂ or spot enlargement factor α, the optical recording medium B, C, ... in The maximum value of the obtained linear velocities V ₂ or the maximum value of the spot magnifications α is used as the linear velocity V ₂ when reproducing the identification information of the optical recording medium mounted using the optical head a or The spot enlargement ratio α is assumed. As described above, after setting the reproduction conditions for reproducing the identification information of the mounted optical recording medium, the type of the optical recording medium mounted is determined using the optical head a. Next, information is recorded and / or reproduced using an optical head corresponding to the discriminated type of the optical recording medium.

  According to the second aspect of the present invention, in the information recording / reproducing apparatus capable of mounting different types of optical recording media in which information is reproduced with light beams having different spot sizes, the identification information recorded on the optical recording medium The first light having the largest spot size among the light beams having different spot sizes is recorded on the optical recording medium mounted on the information recording / reproducing apparatus. There is provided an optical recording medium identification method including irradiating a second light beam having a spot size smaller than the beam and reproducing the identification information of the mounted optical recording medium.

In the method for identifying an optical recording medium of the present invention, the wavelength of the first light beam when reproducing information by irradiating the optical recording medium on which information is reproduced with the first light beam is λ ₁ , and the objective lens Is NA ₁ and the linear velocity of the optical recording medium on which information is reproduced with the first light beam is V ₁ , the maximum reproduction power of the first light beam under the reproduction conditions is Pr _1max, and the second The wavelength of the second light beam when reproducing the identification information of the mounted optical recording medium by irradiating the mounted optical recording medium with the wavelength λ ₂ , the numerical aperture of the objective lens NA ₂ , and the mounting When the linear velocity of the recorded optical recording medium is V ₂ and the reproduction power of the second light beam is Pr ₂ ,
Pr ₂ ≦ {(λ ₂ NA ₁ ) / (λ ₁ NA ₂ )} ² Pr _1max (V ₂ / V ₁ ) ^1/2
It is preferable to set the reproduction power Pr ₂ of the second light beam so that the above relationship is satisfied.

In the method for identifying an optical recording medium of the present invention, the wavelength of the first light beam when reproducing information by irradiating the optical recording medium on which information is reproduced with the first light beam is λ ₁ , and the objective lens Is NA ₁ and the linear velocity of the optical recording medium on which information is reproduced with the first light beam is V ₁ , the maximum reproduction power of the first light beam under the reproduction conditions is Pr _1max, and the second The wavelength of the second light beam when reproducing the identification information of the mounted optical recording medium by irradiating the mounted optical recording medium with the wavelength λ ₂ , the numerical aperture of the objective lens NA ₂ , and the mounting When the linear velocity of the recorded optical recording medium is V ₂ and the reproduction power of the second light beam is Pr ₂ ,
V ₂ ≧ {(λ ₁ NA ₂ ) / (λ ₂ NA ₁ )} ⁴ (Pr ₂ / Pr _1max ) ² V ₁
As the relationship is satisfied, it is preferable to set the linear velocity V ₂ of the loaded optical recording medium.

In the method for identifying an optical recording medium according to the present invention, the wavelength of the first light beam when information is reproduced by irradiating the optical recording medium on which information is reproduced with the first light beam is set to λ ₁ and The numerical aperture of the objective lens is NA ₁ , the maximum reproduction power of the first light beam under the reproduction conditions is Pr _1max, and the attached optical recording medium is irradiated with the second light beam. When reproducing the identification information of the optical recording medium, the wavelength of the second light beam is λ ₂ , the numerical aperture of the objective lens is NA ₂ , the reproduction power of the second light beam is irradiated to Pr ₂ and the mounted optical recording medium. When the enlargement ratio of the spot area of the second light beam to the spot area at the time of in-focus is α,
α ≧ (Pr ₂ / Pr _1max ) {(λ ₁ NA ₂ ) / (λ ₂ NA ₁ )} ²
It is preferable to set the enlargement ratio α of the spot area of the second light beam so that the above relationship is satisfied.

Furthermore, in the method for identifying an optical recording medium of the present invention, the maximum reproduction power Pr _2max of the second light beam that can be applied to the mounted optical recording medium is measured in _advance , and the second light beam is mounted. It is also possible to set the reproduction power of the second light beam when reproducing the identification information of the mounted optical recording medium by irradiating the optical recording medium to the maximum reproduction power Pr _2max or less.

In the method for identifying an optical recording medium of the present invention, the minimum value V _2min of the linear velocity of the mounted optical recording medium that can reproduce information by irradiating the second optical beam to the mounted optical recording medium is measured in advance. The linear velocity of the mounted optical recording medium when reproducing the identification information of the mounted optical recording medium by irradiating the mounted optical recording medium with the second light beam is set to the minimum value V. It is also possible to set it to _{2 min} or more.

In the method for identifying an optical recording medium of the present invention, the enlargement ratio of the spot area of the second light beam that can reproduce information by irradiating the mounted optical recording medium in advance with respect to the spot area at the time of focusing. leave measured the minimum value alpha _min, and a second light beam spot area of the second light beam when reproducing the identification information of the loaded optical recording medium by irradiating the loaded optical recording medium It is also possible to set the enlargement ratio to be equal to or greater than the minimum value α _min .

  According to the information reproducing method and the identifying method of the optical recording medium of the present invention, the identification information of the optical recording medium on which information reproduction is performed with the first light beam having a predetermined spot diameter is set to a spot diameter smaller than the first light beam. Even when the second optical beam having the optical recording medium is irradiated and reproduced, the information recorded on the optical recording medium is not destroyed or the unrecorded area of the optical recording medium is not damaged. The type of optical recording medium can be determined.

  Further, according to the information reproducing method and identification method of the optical recording medium of the present invention, the type of the optical recording medium can be determined using an optical head capable of forming a light beam having a smaller spot diameter (short wavelength). Therefore, even if the frequency of use of an optical recording medium (for example, AOD) compatible with a short wavelength laser is increased in the future, the frequency of switching the optical head after the determination will be low, so that the optical recording mounted on the information recording / reproducing apparatus It is possible to shorten the time from the determination of the medium to the start of recording and reproduction of user information and the like.

  Furthermore, according to the method for identifying an optical recording medium of the present invention, since the optical recording medium can be determined using an optical head for reproducing information from the optical recording medium, the optical recording medium is separated from the optical head. There is no need to newly provide a discrimination means. Therefore, the cost of the information recording / reproducing apparatus can be reduced by using the optical recording medium identifying method of the present invention.

  The optical recording medium identification method of the present invention will be specifically described below with reference to the drawings, but the present invention is not limited to this.

In the first embodiment, an information recording / reproducing apparatus capable of driving an HD-DVD (hereinafter referred to as AOD) capable of recording / reproducing information with a blue laser and a DVD-R capable of recording / reproducing information with a red laser. A method for identifying an optical disc will be described. In this example, the type of the optical disk mounted on the information recording / reproducing apparatus is determined by an optical head (hereinafter also referred to as an AOD head) equipped with a blue laser. When discriminating the type of the optical disk, the output Pr _{2 of the} laser beam irradiated from the AOD head to the optical disk was set so as to satisfy the relationship of the above expression (1).

[optical disk]
First, AOD and DVD-R (16X) prepared in this example will be described. In both the AOD and DVD-R (16X) prepared in this example, a predetermined film (recording layer, reflective layer, etc.) is laminated in a predetermined order on a substrate having a diameter of 120 mm and a thickness of 0.6 mm. The optical disk is 2 mm thick, and both optical disks are interchangeable in shape. In addition, the identification information of the optical disk used in this example was recorded in the BCA provided in the area near the inner periphery of the optical disk for both AOD and DVD-R.

  However, the identification information recorded on the DVD-R may be recorded in a format that allows the AOD head to reproduce and recognize part or all of the identification information as well as the DVD head. preferable. Further, it is preferable that the identification information recorded in the AOD is recorded in such a format that a part or all of the identification information can be reproduced and recognized not only by the AOD head but also by the DVD head.

  A schematic cross-sectional view of the AOD used in this example is shown in FIG. The AOD 20 used in this example is a write-once optical disc having a recording layer containing an organic dye. As shown in FIG. 2, a first intermediate layer 22 and a first intermediate layer 22 are formed on a first substrate 21 made of polycarbonate resin. The first disk 20a in which the first recording layer 23, the first reflective layer 24, and the first cover layer 25 are sequentially formed, and the same configuration as the first disk 20a, that is, on the second substrate 31, the second intermediate layer 32, the second 2 recording layer 33, second reflective layer 34, and second disk 20b on which second cover layer 35 is sequentially formed, and first cover layer 25 and second cover layer 35 face each other through adhesive layer 26. The first disk 20a and the second disk 20b are bonded together.

The AOD 20 used in this example was produced as follows. First, the first substrate 21 is a polycarbonate resin substrate having a diameter of 120 mm and a thickness of 0.6 mm, and was manufactured by injection molding. A groove having a predetermined shape was formed on the surface of the first substrate 21. Next, a ZnS—SiO ₂ film was formed as a first intermediate layer 22 on the first substrate 21 by sputtering. The first intermediate layer 22 was formed by sputtering a ZnS—SiO ₂ target in argon gas. The film thickness of the first intermediate layer 22 was 20 nm. Note that a SiO ₂ film may be used as the first intermediate layer 22.

  Next, a first recording layer 23 containing an organic dye was formed on the first intermediate layer 22. The first recording layer 23 was formed as follows. First, in the carbostyryl compound, 0.5 g of an organic dye represented by the following chemical formula was dissolved in 40 g of octafluoropentanol, and this was ultrasonically dispersed at a temperature of 40 ° C. for 30 minutes. Next, the ultrasonically dispersed solution was filtered with a 0.2 μm filter. Next, the filtered solution was spin-coated on the first substrate 21 at a rotation speed of 1300 rpm, and dried in an oven controlled at 80 ° C. for 30 minutes to form the first recording layer 23.

  Next, an Ag film having a thickness of about 160 nm was formed as a first reflective layer 24 on the first recording layer 23 by sputtering. Next, a precursor of an ultraviolet curable resin was spin coated on the first reflective layer 23 and cured by ultraviolet irradiation to form a first cover layer 25 having a thickness of 10 μm. The first disk 20a was produced as described above.

  Next, the second disk 20b was produced in the same manner as the first disk 20a. Next, the first disk 20 a and the second disk 20 b were bonded together so that the first cover layer 25 and the second cover layer 35 face each other through the adhesive layer 26. As the adhesive layer 26, a slow-acting ultraviolet curable adhesive was used. Thus, AOD20 of this example was produced.

  A schematic cross-sectional view of the DVD-R (16X) used in this example is shown in FIG. The DVD-R 40 used in this example is a write-once type optical recording medium having a recording layer containing an organic dye. As shown in FIG. 3, a recording layer 42 and a reflective layer are formed on a substrate 41 made of polycarbonate resin. The layer 43, the adhesive layer 44, and the dummy substrate 45 are sequentially formed. The DVD-R40 used in this example was manufactured as follows.

  First, Teijin Chemicals polycarbonate AD5503 was used for the substrate 41, and the substrate 41 was produced by injection molding as follows. A stamper having a predetermined pattern formed thereon was mounted on the injection molding machine, and then the predetermined pattern of the mounted stamper was transferred to the substrate by injection molding to form a predetermined pattern such as a preformat area and an information recording area on the substrate 41. . Grooves having a track pitch of 0.74 μm, a half width of 0.32 μm, and a depth of 170 nm were formed in the information recording area. In addition, the shape of the board | substrate 41 was 15 mm in internal diameter, 120 mm in outer diameter, and 0.6 mm in thickness.

  Next, a recording layer 42 containing an organic dye was formed on the preformat surface of the substrate 41. The recording layer 42 was formed as follows. First, a tetrafluoropropanol solution having a concentration of 1.3% by weight of an azo dye represented by the following chemical formula was spin-coated on the substrate 41. In spin coating, 0.5 g of the dye solution is supplied onto a substrate 41 rotating at a rotation speed of 100 rpm by a dispenser, and then the substrate 41 is rotated from a rotation speed of 1000 rpm to 3000 rpm, and finally at 5000 rpm for 2 seconds. It was. At this time, the dye solution was applied so that the thickness of the recording layer 42 in the groove portion formed on the substrate 41 was 130 nm. Next, the substrate 41 coated with the dye solution was dried at 70 ° C. for 1 hour, and further cooled at room temperature for 1 hour. Thus, the recording layer 42 was formed on the substrate 41.

  Next, an Ag film having a thickness of 160 nm was formed as the reflective layer 43 on the recording layer 42 by sputtering. Next, an ultraviolet curable resin material was spin-coated as an adhesive layer 44 on the reflective layer 43, and a dummy substrate 45 was placed thereon. As the dummy substrate 45, a polycarbonate substrate having an inner diameter of 15 mm, an outer diameter of 120 mm, and a thickness of 0.6 mm was used. Next, the adhesive layer 44 was cured by irradiating ultraviolet rays from the dummy substrate 45 side, and the substrate 41 and the dummy substrate 45 on which the above-described layers were formed were bonded together. Thus, DVD-R40 of this example was produced. It is possible to coat the surface of the substrate 41 opposite to the recording layer 42 side with a hard coat material.

[Information recording / playback device]
In this example, an optical head (AOD head) compatible with an AOD equipped with a laser having a wavelength λ ₂ = 405 nm (blue) and an objective lens having a numerical aperture NA ₂ = 0.65, and a wavelength λ ₁ = 650 nm (red) ) And an optical head (DVD head) compatible with a DVD-R equipped with an objective lens having a numerical aperture NA ₁ = 0.60 was used. In the information recording / reproducing apparatus of this example, an AOD head is used as an optical head for discriminating the type (AOD or DVD-R) of the mounted optical disk.

[Optical disc identification method]
Next, an optical disk identification method in this example will be described. First, the maximum reproduction power Pr _1max of the red laser that can be irradiated when information is reproduced from the DVD-R (16X) by the DVD head (red laser) (maximum value of the reproduction laser power that does not destroy the recording data of the DVD-R) Was measured. A method for measuring the maximum reproduction power Pr _1max of the red laser that can be irradiated _onto the DVD-R is as follows. First, a laser beam with a predetermined laser power Pe ₁ was continuously emitted to the information recording area of the DVD-R with a DVD head. Next, a reproduction signal was detected by irradiating a laser beam with a reproduction power of 0.7 mW used for normal information reproduction of the DVD-R onto a position irradiated with the laser beam with the laser power Pe ₁ . The above measurement was repeated while changing the laser power Pe _1. In this measurement, the linear velocity of DVD-R was 3.5 m / s.

FIG. 1 shows the characteristics of the change amount of the reproduction signal output with respect to the laser power Pe ₁ obtained by the above measurement. As apparent from FIG. 1, when the laser power Pe ₁ is made larger than a certain laser power Pe ₁ value (Pr _{1max in} FIG. 1), the reproduction signal output changes, and when the laser power Pe ₁ is further increased, the reproduction signal output is output. The characteristic that the amount of change is saturated was obtained. In this example, the reproduction power Pr _1max was 2.1 mW. Reason for the reproduced signal output is changed by increasing the laser power Pe ₁ than the reproduction power Pr _1max, when irradiated with a laser beam DVD-R with a large laser power than the reproduction power Pr _1max, a recording layer containing an organic dye This is because the area of the recording layer that has been heated due to an irreversible change has changed to a state corresponding to “recording”, and the intensity of the reproduced signal obtained from that area has changed. From this result, in this example, when information is reproduced from the DVD-R with the DVD head, if the laser power is made larger than Pr _1max = 2.1 mW, the information recorded on the DVD-R is destroyed or not recorded. It was found that the area could be damaged. Therefore, in this example, it was found that the laser power Pr _1max = 2.1 _{mW in} FIG. 1 is the maximum reproduction power of the red laser that can be irradiated when reproducing information on the DVD-R with the DVD head.

Next, the maximum reproduction power Pr _1max of the red laser that can be irradiated during the information reproduction of the DVD-R measured by the above method is _expressed by the above equation (1), that is,
Pr ₂ ≦ {(λ ₂ NA ₁ ) / (λ ₁ NA ₂ )} ² Pr _1max (V ₂ / V ₁ ) ^1/2 = Pr _2max
And the maximum reproduction power Pr _2max of the blue laser that can be irradiated when reproducing the identification information of the DVD-R with the AOD head was obtained. In this example, the linear velocity at the time of discriminating the optical disk is V ₁ = V ₂ = 3.5 m / s. As a result, the maximum reproduction power Pr _{2max of the} blue laser that can be applied to the DVD-R by the AOD head was about 0.7 mW. That is, in this example, when the identification information of the optical disk mounted on the information recording / reproducing apparatus is reproduced by the AOD head, the reproduction power Pr ₂ of the blue laser is set to Pr _2max = about 0.7 mW or less, so Even when the DVD-R is loaded, the type of the optical disk can be determined without destroying the recorded information of the DVD-R or damaging the unrecorded portion.

[Recording and playback method]
Next, a series of operations from discriminating the optical disc to recording and / or reproducing user information etc. in the information recording / reproducing apparatus used in this example will be described with reference to FIG. The information of the maximum reproduction power Pr _2max of the blue laser that can be irradiated when reproducing the identification information of the DVD-R by the AOD head obtained from the above equation (1) is stored in advance in the memory or the like of the information recording / reproducing apparatus. Keep it.

First, an optical disk is inserted into the information recording / reproducing apparatus (step S11). Next, the AOD head is driven to place the AOD head on the area (BCA) where the identification information of the optical disk is recorded (step S12). Next, the information of the maximum reproducible power Pr _2max of the _irradiable blue laser stored in the memory or the like of the information recording / reproducing apparatus is read, and the regenerating condition (blue laser regenerating power Pr ₂ ) at the time of determination is set (step S13). At this time, the reproduction power Pr ₂ of the blue laser is set to a predetermined value that is equal to or less than the maximum reproduction power Pr _{2max of the} blue laser that can be irradiated. Next, a laser beam having a predetermined reproduction power Pr ₂ that has been set is applied to the area where the identification information of the optical disk is recorded, and the identification information of the optical disk is reproduced based on the reflected light from the optical disk, and the type of optical disk (DVD -R or AOD) is determined (step S14).

  If it is determined in step S14 that the optical disk mounted is AOD, the AOD head is placed at a predetermined position for recording and / or reproducing information on the optical disk, and the recording / reproducing condition of the AOD head is normally set to AOD. Are set as conditions for recording and / or reproducing user information or the like (step S15). Next, information is recorded and / or reproduced by irradiating a predetermined position of the optical disk with laser light (blue) under the recording and reproducing conditions set in step S15 (step S16).

  If it is determined in step S14 that the optical disk mounted is a DVD-R, the optical head is switched from the AOD head to the DVD head, and the DVD head is moved to a predetermined position for recording and / or reproducing information on the optical disk. Arrange (step S17). Next, the recording / reproducing conditions of the DVD head are normally set to the conditions for recording and / or reproducing user information or the like on the DVD-R (step S18). Next, information is recorded / reproduced by irradiating a predetermined position on the optical disc with laser light (red) under the recording / reproduction conditions set in step S18 (step S19).

[Discrimination test]
Actually, the optical disc was discriminated using the identification method of this example. In this example, in order to further reduce the risk of data destruction when the DVD-R is mounted, the maximum reproduction power Pr _2max that can be irradiated with the reproduction power Pr ₂ of the laser beam emitted from the AOD head at the time of discriminating the optical disk = The value was not set to about 0.7 mW, and Pr ₂ was set to 0.35 mW with a margin. As a result, it was possible to discriminate regardless of the type of optical disc loaded in the information recording / reproducing apparatus. Further, even when the DVD-R is mounted, the identification information of the optical disc can be reproduced without destroying the information recorded on the DVD-R.

However, it was subjected to determination of the optical disk reproduction power Pr ₂ of the laser beam irradiated from the AOD head to the optical disk as 0.8 mW, it was possible to determine without any problem when the AOD is mounted in the information recording and reproducing apparatus However, when the DVD-R was loaded in the information recording / reproducing apparatus, a part of the data recorded on the DVD-R was destroyed. Information was reproduced using a DVD head after discrimination for a DVD-R in which a part of this data was destroyed, but an error occurred.

In this example, information reproduction was performed 10,000 times by irradiating the same track of the DVD-R with a blue laser having a reproduction power Pr ₂ = 0.55 mW. As a result, no increase in jitter was observed. However, when a similar measurement was performed using a blue laser with a reproduction power Pr ₂ = 0.7 mW, the jitter increased by 1%. When the identification information of a DVD-R compatible with a red laser is reproduced with a blue laser as in the present invention, the durability for 10,000 identical track reproductions is not necessary. However, for example, when taking into account the normal reproduction of user information recorded on a DVD-R with a blue laser, it is necessary to consider the durability against 10,000 identical track reproductions in design. In that case, it is preferable to set the reproduction power Pr ₂ of the blue laser lower than the maximum reproduction power Pr _2max that can be irradiated. Specifically, from the above measurement results, the reproduction power Pr ₂ of the blue laser for discriminating the optical disc is _reduced to about 80% or less (about 0.55 mW or less in this example) of the maximum reproduction power Pr _2max that can be irradiated onto the DVD-R. It was found that setting is more preferable.

  As in this example, when the wavelengths of the two optical systems are largely separated at 650 nm and 405 nm, particularly when the spot area ratio is twice or more, the optical disk is irradiated from each optical head. The difference in energy density of the laser light is increased. Therefore, in such a case, if the reproduction condition of the short wavelength laser at the time of discriminating the optical disk is set to the reproduction condition used at the time of reproducing user information etc., there is a great risk of destroying information recorded on the optical disc compatible with the long wavelength laser. Get higher. Therefore, as in this example, in the information recording / reproducing apparatus including a plurality of optical heads having large wavelength differences, the effect of the identification method of the present invention is further exhibited.

Theoretically, the maximum reproduction power Pr _2max of the blue laser (second light beam) that does not cause data destruction of the DVD-R (first recording medium) can be obtained by the above equation (1). ) Instead of actually measuring the maximum reproduction power Pr _1max of the red laser (first light beam) in the formula, it is usually set when reproducing the DVD-R (first recording medium) with the red laser (first light beam). It is also possible to set the reproduction power Pr ₂ at the time of discriminating the optical disk by substituting the reproduction power Pr ₁ into the equation (1). That is,
Pr ₂ ≦ {(λ ₂ NA ₁ ) / (λ ₁ NA ₂ )} ² Pr ₁ (V ₂ / V ₁ ) ^1/2 (1 ′)
As you may set the reproduction power Pr ₂ of the blue laser at an optical disc discrimination (second light beam). According to this method, it is possible to easily set the reproduction power Pr ₂ without actually measuring the maximum reproduction power Pr _1max . However, when the reproduction condition at the time of discriminating the optical disc is set using the equation (1 ′), the settable range is included in the range set using the equation (1). It becomes narrower than the range set by using. Therefore, it is preferable to select the expression (1) or (1 ′) as appropriate according to the situation.

For example, as in this embodiment, when the reproduction power Pr ₁ for normal reproduction of a DVD-R with a DVD head is 0.7 mW and the linear velocities V ₁ and V ₂ are both 3.5 m / s, the above ( The right side of the expression 1 ′) is 0.23 mW. Therefore, in this embodiment, the reproduction power Pr ₂ when reproducing the DVD-R identification information using the laser light (second light beam) of the AOD head may be set to 0.23 mW or less. Actually, when the optical disc was discriminated under these conditions, it was possible to discriminate the optical disc regardless of the type of the optical disc loaded in the information recording / reproducing apparatus. Even when the DVD-R is mounted, the identification information of the DVD-R can be reproduced without destroying the information recorded on the DVD-R.

In Example 2, the maximum reproduction power Pr _2max that can be irradiated with the blue laser when reproducing the identification information of the optical disk by the AOD head was measured and obtained. A similar effect was obtained by discriminating the optical disk by the same method as in Example 1 except that the maximum reproduction power Pr _2max that can be irradiated with the blue laser was actually measured. The maximum reproduction power Pr _2max that can be irradiated with the blue laser was measured as follows in the same manner as the method for measuring the maximum reproduction power Pr _1max of the red laser that can be irradiated onto the DVD-R described with reference to FIG.

First, with an AOD head (wavelength λ ₂ = 405 nm, lens numerical aperture NA ₂ = 0.65), a DVD-R information recording area was continuously emitted with a laser beam having a predetermined laser power Pe ₂ . Next, a signal was detected by irradiating the position where the laser beam with the laser power Pe ₂ was irradiated with the reproduction light whose reproduction laser power was set to a low value of 0.15 mW. The above measurement was repeated while changing the laser power Pe _2. In this measurement, the linear velocity _{V 1} of the DVD-R was 3.5 m / s. This measurement is performed in a state where the limit reproduction laser power at which data destruction of the DVD-R occurs when the DVD-R is irradiated with laser light from the AOD head. It is preferable to set the reproducing laser power when detecting a signal as low as possible.

FIG. 5 shows the characteristics of the change amount of the reproduction signal output with respect to the laser power Pe ₂ obtained by this measurement. As apparent from FIG. 5, when the laser power Pe ₂ becomes larger than a value of the laser power Pe ₂ (Pr _{2max in} FIG. 5), the reproduction signal output changes, and when the laser power Pe ₂ further increases, the reproduction signal output is output. The characteristic that the amount of change is saturated was obtained. In this example, the laser power Pr _2max was 0.7 mW. From this result, in this example, when the DVD-R information is reproduced by the AOD head, if the laser power is made larger than Pr _2max = 0.7 mW, the information recorded on the DVD-R is destroyed or not recorded. It was found that the area could be damaged. That is, it was found that the maximum reproduction power Pr _2max that can be irradiated with the blue laser when reproducing the identification information of the optical disk by the AOD head is 0.7 mW.

As described above, the maximum reproduction power Pr _2max that can be irradiated by the blue laser obtained from the characteristic experiment of FIG. 5 is 0.7 mW, which is consistent with the maximum reproduction power Pr _2max obtained from the expression (1) of Example 1. did. From this result, it is understood that the method of _obtaining the maximum reproduction power Pr _2max that can be irradiated with the blue laser when reproducing the identification information of the optical disk by the AOD head may be obtained by any of the methods of the first and second embodiments. It was.

In the third embodiment, as in the first embodiment, in an information recording / reproducing apparatus capable of driving an AOD capable of recording / reproducing information with a blue laser and a DVD-R capable of recording / reproducing information with a red laser. An optical disc identification method will be described. Further, in this example, the type of the optical disc mounted on the information recording / reproducing apparatus was determined by the AOD head as in the first embodiment. And, in this example, in determining the type of the optical disc, (2) or (2 ') so as to satisfy the relation of equation to set the linear velocity V ₂ of the optical disc when the optical disc discrimination. That is, in this example, the linear velocity of the optical disk when reproducing the identification information of the optical disk with the AOD head is set to V ₂ V ₂ ≧ {(λ ₁ NA ₂ ) / (λ ₂ NA ₁ )} ⁴ (Pr ₂ / Pr _1max ) ² V ₁
Or V ₂ ≧ {(λ ₁ NA ₂ ) / (λ ₂ NA ₁ )} ⁴ (Pr ₂ / Pr ₁ ) ² V ₁
Was set to satisfy the relationship.

When determining the type of the optical disc in AOD head, the linear velocity V ₂ of the optical disk except set as described above, in the same manner as in Example 1, was subjected to determination of the optical disc. The AOD, DVD-R, and information recording / reproducing apparatus prepared in this example were the same as those used in Example 1. Further, in the series of operations from discriminating the optical disk to recording and / or reproduction of user information and the like in this example, in step S13 in the flowchart of FIG. 4 described in the first embodiment, the above (2) or (2 ′) except that setting the linear velocity V ₂ of the optical disc so as to satisfy the equation, was recorded and / or reproducing information by the same procedure as that in example 1.

The identification method of the optical disc in this example is as follows. First, the maximum reproduction power Pr _1max of the red laser that can be irradiated _{onto the} DVD-R with the DVD head was obtained by the same measurement method as in Example 1 (the measurement method described in FIG. 1). As a result, Pr _1max was 2.1 mW. Next, by substituting this maximum reproduction power Pr _1max into the above equation (2), the minimum value V _2min of the linear velocity V ₂ of the optical disc when the identification information of the optical disc is reproduced by the AOD head is obtained. In this example, the information of the minimum linear velocity V _2min at the time of discriminating the optical disc obtained from the above equation (2) is stored in advance in the memory of the information recording / reproducing apparatus before discriminating the optical disc. Further, when the minimum linear velocity V _2min at the time of optical disc discrimination is obtained from the above equation (2), the reproduction power Pr ₂ of the laser light emitted from the AOD head reproduces a predetermined value, for example, AOD user information. It is preferable to set to the optimum power.

Next, when discriminating the optical disc loaded in the information recording / reproducing apparatus, information on the minimum linear velocity V _2min when discriminating the optical disc stored in the memory or the like of the information recording / reproducing device is read, and the linear velocity V _{2 of the} optical disc is read. Is set to be equal to or greater than the minimum value V _{2 min} (step S13 in the flowchart of FIG. 5). Next, the optical disk is driven at a predetermined linear velocity V ₂ that is set, and laser light (blue) is emitted from the AOD head to the optical disk. Then, the identification information of the optical disk is reproduced based on the reflected light from the optical disk, and the type of the optical disk is determined.

In this example of the optical disc identification method, even if the optical disc loaded is a DVD-R, the optical disc is discriminated so that the energy density of the irradiated blue laser becomes an energy density that does not destroy the information recorded on the DVD-R. since the linear velocity V ₂ of the is adjusted when it is possible to discriminate the optical disc without destroying the information recorded on the DVD-R.

In the identification method of this example, the minimum linear velocity V _2min at the time of discriminating the optical disc may be obtained using equation (2 ′), and the linear velocity V ₂ at the discriminating optical disc may be set. For _example, Pr 1 = 0.7 _mW, as Pr 2 = 0.35 mW and _V 1 = 3.5m / s, the seek _{V 2min} from (2 _') where the _V 2min = 8m / s. Further, assuming that Pr ₁ = 0.7 mW, Pr ₂ = 0.3 mW, and V ₁ = 3.5 m / s, V _2min is obtained from the equation (2 ′), V _2min = 5.9 m / s. Further, when the minimum linear velocity V _2min at the time of discriminating the optical disk is obtained using the equation (2 ′), the users of DVD-R and AOD are actually used as the laser powers Pr ₁ and Pr ₂ in the equation (2 ′). Optimal laser powers Pr ₁ and Pr ₂ for reproducing information and the like can be used. In this case, there is no need to set the reproduction power again after discriminating the optical disc, so that the time from discriminating the optical disc to the start of information recording and / or reproduction can be further shortened.

Next, the optical disc was actually discriminated using the optical disc identification method of this example. Here, the condition of the minimum linear velocity _{V 2min} optical disc discrimination when determined using the (2 ') where the power of the blue laser during disc discriminating and _Pr 2 = 0.3 mW, linear velocity _{V 2} Was set to 6.6 m / s. As a result, it is possible to discriminate regardless of the type of the optical disc loaded in the information recording / reproducing apparatus, and even when the DVD-R is loaded, the identification information of the optical disc is destroyed without destroying the information recorded on the DVD-R. Was able to play. In addition, even when the blue laser power at the time of optical disc discrimination is set to Pr ₂ = 0.35 mW and the linear velocity V _{2 is set} to 8 m / s, discrimination is performed regardless of the type of optical disc loaded in the information recording / reproducing apparatus. It was possible to discriminate without destroying the information recorded on the DVD-R.

However, when the power of the blue laser at the time of optical disc discrimination is Pr ₂ = 0.3 mW and the linear velocity V ₂ is 5.9 m / s or less, or the power of the blue laser at the time of optical disc discrimination is Pr ₂ = 0. and 35 mW, when the linear velocity V ₂ and less 8.0 m / s, but AOD in the information recording and reproducing apparatus is able to determine without any problem when it is mounted, is DVD-R in the information recording and reproducing apparatus When it was installed, there was a case where a part of the data recorded on the DVD-R was destroyed. Information was reproduced using a DVD head after discrimination for a DVD-R in which a part of this data was destroyed, but an error occurred.

In Example 4, the minimum value V _2min of the linear velocity of the optical disk when reproducing the identification information of the optical disk with the AOD head was obtained by actual measurement. Except for actually measuring the minimum value V _2min of the linear velocity of the optical disc, the optical disc was determined in the same manner as in Example 3, and the same effect was obtained. The linear velocity V _2min of the optical disc at the time of disc discrimination was measured as follows.

A DVD-R on which predetermined information is recorded is mounted on an information recording / reproducing apparatus, and the DVD-R is irradiated with laser light having a predetermined reproduction power Pr _{2 by} an AOD head while changing the linear velocity V ₂ of the DVD-R. Then, the change of the reproduction signal was examined. Here, Pr ₂ = 0.3 mW. As a result, it was found that when the linear velocity was made lower than V ₂ = 0.65 m / s, a change appeared in the reproduction signal, and data was destroyed. Therefore, in this example, it was found that the minimum linear velocity (limit reproduction linear velocity) V _2min for reproducing with the AOD head without destroying the information recorded on the DVD-R is 0.65 m / s. .

Actually, when the optical disc was determined by setting the reproduction power Pr ₂ of the blue laser at the time of optical disc discrimination to 0.3 mW and the linear velocity V ₂ to 0.65 m / s or more, it was mounted on the information recording / reproducing apparatus. It was possible to discriminate regardless of the type of optical disk to be used. Further, even when the DVD-R is mounted, the identification information of the optical disc can be reproduced without destroying the information recorded on the DVD-R.

However, if the reproduction power of the blue laser at the time of discriminating the optical disc is set to Pr ₂ = 0.3 mW and the linear velocity V ₂ is made smaller than 0.65 m / s, the discriminating is performed without any problem when an AOD is attached to the information recording / reproducing apparatus. However, when the DVD-R was installed in the information recording / reproducing apparatus, a part of the data recorded on the DVD-R was destroyed. Information was reproduced using a DVD head after discrimination for a DVD-R in which a part of this data was destroyed, but an error occurred.

In the fifth embodiment, as in the first embodiment, in an information recording / reproducing apparatus capable of driving an AOD capable of recording / reproducing information with a blue laser and a DVD-R capable of recording / reproducing information with a red laser. An optical disc identification method will be described. Further, in this example, as in the first embodiment, the type of the optical disk mounted on the information recording / reproducing apparatus was determined by the AOD head. In this example, when discriminating the type of the optical disk, the spot size is widened by defocusing the laser light applied to the optical disk from the AOD head. Specifically, so as to satisfy the relationship of the above expression (3), that is,
α ≧ (Pr ₂ / Pr _1max ) {(λ ₁ NA ₂ ) / (λ ₂ NA ₁ )} ²
In order to satisfy the above relationship, the enlargement ratio α of the spot area of the laser beam irradiated from the AOD head to the optical disc with respect to the spot area at the time of focusing is set.

  In this example, when the type of the optical disk is discriminated by the AOD head, except that the enlargement ratio α of the spot area of the laser light irradiated from the AOD head to the optical disk is adjusted so as to satisfy the above relationship. In the same manner as in Example 1, the optical disk was discriminated. The AOD, DVD-R, and information recording / reproducing apparatus prepared in this example were the same as those used in Example 1. Further, in the series of operations from discriminating the optical disc to recording and / or reproducing user information in this example, the above equation (3) is satisfied in step S13 in the flowchart of FIG. 4 described in the first embodiment. Information was recorded and / or reproduced in the same procedure as in Example 1 except that the enlargement ratio α of the spot area of the laser light irradiated from the AOD head to the optical disk was set.

The identification method of the optical disc in this example is as follows. First, the maximum reproduction power Pr _1max of the red laser that can be irradiated _{onto the} DVD-R with the DVD head was obtained by the same measurement method as in Example 1 (the measurement method described in FIG. 1). As a result, Pr _1max was 2.1 mW. When this maximum reproduction power Pr _1max is substituted into the above equation (3), the minimum value α _min of the enlargement factor α of the spot area of the laser light irradiated from the AOD head to the optical disc at the time of disc discrimination is obtained. In this example, the information of the minimum enlargement ratio α _min at the time of discriminating the optical disc obtained from the above equation (3) is stored in advance in the memory of the information recording / reproducing apparatus before discriminating the optical disc. Further, when the minimum enlargement ratio α _min at the time of optical disc discrimination is obtained from the above equation (3), the reproduction power Pr ₂ of the laser light emitted from the AOD head reproduces a predetermined value, for example, user information of AOD. It is preferable to set the optimum reproduction power.

Next, when discriminating the optical disc loaded in the information recording / reproducing apparatus, the information of the minimum enlargement ratio α _min at the time of discriminating the optical disc stored in the memory or the like of the information recording / reproducing device is read, and the AOD head at the time of discriminating the optical disc Is set so that the enlargement ratio α of the spot area of the laser light irradiated onto the optical disk from the first to the minimum value α _min (step S13 in the flowchart of FIG. 4). Next, the laser beam is defocused and irradiated onto the optical disc so that the magnification α of the spot area of the laser beam irradiated onto the optical disc from the AOD head becomes a set value. Then, the identification information of the optical disk is reproduced based on the reflected light from the optical disk, and the type of the optical disk is determined.

  In the identification method of this example, even if the mounted optical disk is a DVD-R, the energy density of the laser beam (blue) irradiated to the DVD-R from the AOD head does not destroy the information recorded on the DVD-R. The laser beam is defocused so as to obtain an energy density. Therefore, it is possible to determine the optical disk without destroying information recorded on the DVD-R.

Here, a method of adjusting the magnification α of the spot area of the laser beam by defocusing the laser beam irradiated on the optical disk from the AOD head will be specifically described with reference to FIG. Conventionally, when a laser beam is focused on a recording film surface, first, the lens is positioned at a position farthest from the disk, and the lens is gradually brought closer to the disk and focused. At this time, a focus detection signal called an S-shaped curve as shown in FIG. 6 is obtained. In the S-shaped curve of FIG. 6, the horizontal axis is the focus position of the laser beam, and the focal position of the laser beam is farther from the optical disc (the lens is separated from the optical disc) from the right to the left of the S-shaped curve on the drawing. Become a direction. During conventional information recording / reproduction, the focus of the optical system (lens) is controlled so that the focus detection signal is at the zero-cross position of the S-shaped curve (point Z _{0 in} FIG. 6).

  However, in the identification method of this example, at the time of discriminating the optical disc, the laser beam is defocused and applied to the optical disc in order to adjust the energy density of the laser beam applied to the optical disc. Specifically, the focal position of the laser beam is servo-controlled while a predetermined offset amount is given to the automatic focus adjustment circuit in the information recording / reproducing apparatus. There is a correlation between the offset amount from the zero cross position of the S-shaped curve and the spot size of the laser light irradiated to the optical disk, and the larger the offset amount from the zero cross position of the S-shaped curve, the larger the laser light irradiated to the optical disk. The spot size of will also increase. Therefore, the enlargement ratio α of the spot area of the laser light irradiated onto the optical disk can be adjusted by adjusting the offset amount.

Note that when obtaining the minimum magnification α _min of the laser beam when discriminating the optical disc from the above equation (3), the maximum reproduction power Pr _{1max of the} red laser that can be radiated to the DVD-R and the blue color _emitted from the AOD head when discriminating the optical disc As the laser reproduction power Pr ₂ , optimum laser powers Pr ₁ and Pr ₂ for actually reproducing user information and the like from the DVD-R and AOD, respectively, may be used. In this case, there is no need to set the reproduction power again after discriminating the optical disc, so that the time from discriminating the optical disc to starting recording and / or reproduction of user information can be further shortened.

For example, assuming that Pr ₁ = 0.7 mW and Pr ₂ = 0.35 mW, the minimum enlargement ratio α _min of the spot area of the laser light is obtained from the equation (3), then α _min = about 1.5. Further, when Pr ₁ = 0.7 mW and Pr ₂ = 0.3 mW, the minimum expansion ratio α _min of the spot area is α _min = about 1.3.

Next, the optical disc was actually discriminated using the optical disc identification method of this example. In this measurement, when obtaining the minimum magnification α _min of the laser light when discriminating the optical disk from the above equation (3), instead of the maximum reproduction power Pr _1max of the red laser that can be irradiated to the DVD-R, DVD The optimum laser power Pr ₁ = 0.7 mW for reproducing user information and the like from -R was substituted and determined so that the laser beam magnification α was equal to or greater than the minimum magnification α _min . Specifically, α = 1.3 was obtained with Pr ₂ = 0.3 mW and V ₂ = 3.5 m / s, and the optical disc was determined under these conditions. As a result, it is possible to discriminate regardless of the type of the optical disk mounted on the information recording / reproducing apparatus, and even when the DVD-R is mounted on the information recording / reproducing apparatus, the information recorded on the DVD-R is not destroyed. The optical disc could be identified. Further, even when Pr ₂ = 0.35 mW, V ₂ = 3.5 m / s and α = 1.5 is obtained, the determination can be made regardless of the type of the optical disc loaded in the information recording / reproducing apparatus. It was possible to discriminate the optical disk without destroying information recorded on the DVD-R.

Note that the range of the enlargement rate α obtained by the above equation (3) is theoretically the range of the enlargement rate α that does not cause the data destruction at the time of optical disc discrimination. As described above, the DVD in the equation (3) The method of obtaining the range of the enlargement ratio α by substituting the optimum laser power Pr ₁ when reproducing user information from the DVD-R instead of the maximum reproduction power Pr _1max of the red laser that can be irradiated to −R is as follows: This is a method that can easily and safely set the reproduction condition for discriminating the optical disc. in this way,
α ≧ (Pr ₂ / Pr ₁ ) {(λ ₁ NA ₂ ) / (λ ₂ NA ₁ )} ² (3 ′)
Is used to obtain a settable range of the enlargement ratio α. In this case, since it is not necessary to actually measure the maximum reproduction power Pr _1max , the setting range of the enlargement ratio α can be easily obtained. The relationship between the equations (3) and (3 ′) is the relationship between the equations (1) and (1 ′) when setting the reproduction power Pr ₂ described above, or when setting the linear velocity V _2. This corresponds to a relationship similar to the relationship between the equations (2) and (2 ′).

However, if Pr ₂ = 0.7 mW and V ₂ = 3.5 m / s and the laser beam magnification is α = 1.0, that is, in the in-focus state, an AOD is mounted on the information recording / reproducing apparatus. However, when the DVD-R was installed in the information recording / reproducing apparatus, a part of the data recorded on the DVD-R was destroyed. Information was reproduced using a DVD head after discrimination for a DVD-R in which a part of this data was destroyed, but an error occurred.

In Example 6, the minimum value α _min of the enlargement factor α of the spot area of the laser beam when reproducing the identification information of the optical disc with the AOD head was obtained by actual measurement. A similar effect was obtained by discriminating the optical disc in the same manner as in Example 5 except that the minimum magnification α _min of the spot area of the laser beam was actually measured. The minimum magnification α _min of the laser beam spot area at the time of discriminating the optical disk was measured as follows.

A DVD-R in which predetermined information is recorded is mounted on an information recording / reproducing apparatus, and a laser beam having a predetermined reproduction power Pr ₂ (= 0.8 mW) is applied to the recording area of the DVD-R by an AOD head (enlargement rate). The DVD-R is irradiated while changing α). Specifically, the DVD-R is irradiated with the laser beam while the focal position of the laser beam is close to the DVD-R, and the information recorded on the DVD-R is recorded. Reproduce. At this time, if the focal position of the laser light is gradually brought closer to the DVD-R, a change appears in the reproduction signal when the laser light is brought closer to a certain focal position. The focal position of the laser beam is the limit reproduction focal position when the DVD-R is reproduced by the AOD head. If the focal position of the laser beam is closer to the DVD-R than the focal position, the data recorded on the DVD-R is recorded. May be destroyed. Therefore, the minimum value α _min of the laser beam magnification α during optical disc discrimination is obtained from the offset amount corresponding to the limit reproduction focal position of the laser beam.

Indeed, the reproduction power Pr ₂ of the laser beam irradiated from the AOD head DVD-R as 0.8 mW, was measured the approach limit position of the optical disk of the focal position of the laser beam. The approach limit position was detected at a position where the focal point of the laser beam gradually approached the optical disk from a distance and a change in the reproduction signal appeared. As a result, the detected position was a position corresponding to the enlargement ratio α = 1.14. By defocusing the laser beam so that the focal position of the laser beam is far from the offset position, the information recorded on the DVD-R is destroyed even when the DVD-R is installed in the information recording / reproducing apparatus. It turned out that it can be distinguished without doing.

  In the first to sixth embodiments, when the type of the optical disk is determined by the optical head (AOD head) equipped with the blue laser, the data recorded on the mounted optical disk is irradiated from the AOD head so as not to be destroyed. Although an example in which the laser power, the laser beam spot size, or the linear velocity of the optical disk is adjusted has been described, the present invention is not limited to this. Moreover, you may adjust the energy density of the laser beam irradiated from an AOD head combining these adjustment methods.

  In the first to sixth embodiments, the solution to the problem in discriminating the optical disc has been described, but the present invention is not limited to this. That is, the above-described problem in discriminating an optical disk is a problem that occurs in common when a signal is reproduced using an optical system that does not support the predetermined optical disk. The present invention can also be applied to cases other than the case where the determination is made, for example, in the case of recording / reproducing user information.

  In the first to sixth embodiments, the optical disc identification information is reproduced based on the reflected light from the optical disc when the optical disc is discriminated. However, the present invention is not limited to this, and the optical disc identification information is used based on the transmitted light of the optical disc. You may replay it.

[Application example]
In this example, an example of a recording / reproducing system using the optical disk identification method of the present invention will be described. In the first to sixth embodiments described above, in the near future, the usage frequency of the optical disk will increase in the AOD compatible with the blue laser than the DVD compatible with the red laser, that is, the usage frequency of the optical disk of the large capacity standard will increase. Assuming a system for discriminating an optical disc with an AOD head equipped with a blue laser. However, even if the frequency of use of large-capacity optical discs increases in the future, it is natural that some users may use DVDs as the main optical disc. Therefore, in this example, a recording / reproducing system that takes into account the user that the optical disk to be used is mainly a DVD will be described.

  In this example, a recording / reproducing system capable of driving an AOD capable of recording / reproducing information with a blue laser and a DVD capable of recording / reproducing information with a red laser will be described. FIG. 7 shows a recording / reproducing procedure of information on the optical disc in the recording / reproducing system of this example. In the recording / reproducing system of this example, as shown in FIG. 7, a processing system that uses an AOD head when discriminating an optical disk (a system that performs the step of broken line S10 in FIG. 7) and a processing system that uses a DVD head when discriminating an optical disk (FIG. 7). System for performing the step of the broken line S20 in the middle). The recording / reproducing system of this example includes switching means (means for performing step S0 in FIG. 7, hereinafter referred to as an optical head switch) that can select an optical head to be driven in order to determine the type of the optical disk.

  However, this optical head switch uses an optical head that is driven first (used for discriminating an optical disc) when the optical disc is mounted on an information recording / reproducing apparatus, depending on the type of optical disc frequently used by the user. It is preferable that it has the function which can be selected by. For example, as an optical head switch, the recording / reproducing apparatus may be provided with mechanical switching means such as a dip switch, or the information recording / reproducing apparatus is connected to an external device such as a personal computer and is first driven on the software from the outside. Switching means that can switch the optical head to be used may be used. That is, as the optical head switch, any means can be used according to the system configuration and the like.

  In the recording / reproducing system of this example, for example, if the user is a user who frequently uses a DVD, the lead time is shortened as an optical head that is first driven when the optical disc is mounted on the information recording / reproducing apparatus. It is preferable to select a DVD head. Therefore, for such a user, the processing system of step S20 in FIG. 7 may be selected in advance by an optical head switch. Conversely, if the user is a user who frequently uses AOD, the AOD head is selected as the first optical head to be driven when the optical disc is mounted on the information recording / reproducing apparatus in terms of shortening the lead time. Is preferable. Therefore, for such a user, the processing system of step S10 in FIG. 7 may be selected in advance by an optical head switch.

  Thus, according to the type of optical disk frequently used by the user, the optical head to be driven first when the optical disk is mounted on the information recording / reproducing apparatus with the optical head switch can be selected from the discrimination of the optical disk. A series of processing time until recording and / or reproduction of information or the like can be comprehensively shortened in accordance with the usage form of the user.

  Next, a series of operations from discriminating the optical disc to recording and / or reproducing user information etc. in the recording / reproducing system of this example will be described with reference to FIG.

  First, light that is first driven (used for discriminating an optical disk) in advance (for example, at the time of purchase of the apparatus) when the optical disk is mounted on the information recording / reproducing apparatus according to the type of optical disk that the user frequently uses. A head is selected by an optical head switch (step S0). Specifically, if the user frequently uses a DVD, the S20 processing system is selected by the optical head switch, and if the user frequently uses the AOD, the S10 processing system is selected by the optical head switch. .

  When the processing system of S20 is selected in step S0, a DVD head is used as an optical head used for discriminating the optical disc when the optical disc is mounted on the information recording / reproducing apparatus. Recording and / or reproduction of user information and the like is performed. First, an optical disk is inserted into the information recording / reproducing apparatus (step S21). Next, the DVD head is driven to place the DVD head on an area (for example, BCA) where the identification information of the optical disk is recorded (step S22). Next, the reproduction condition for reproducing the identification information of the optical disk by the DVD head is set to the reproduction condition normally used for reproducing the user information of the DVD (step S23). Next, a laser beam (red) having a predetermined reproduction power set is irradiated onto the area where the identification information of the optical disk is recorded, and the identification information of the optical disk is reproduced based on the reflected light from the optical disk, and the type of optical disk ( DVD or AOD) is discriminated (step S24).

  If it is determined in step S24 that the optical disk loaded is a DVD, the DVD head is placed at a predetermined position for recording and / or reproducing user information on the optical disk, and the reproduction conditions of the DVD head are left as they are. Recording and / or reproduction of user information or the like is performed (step S25).

  If it is determined in step S24 that the optical disk mounted is AOD, the optical head is switched from the DVD head to the AOD head, and the AOD head is placed at a predetermined position for recording and / or reproducing user information on the optical disk. Arrange (step S26). Next, recording / reproducing conditions for the AOD head are set (step S27). Next, the laser beam (blue) is irradiated to a predetermined position of the optical disc under the recording / reproduction conditions set in step S27 to record and / or reproduce user information and the like (step S28).

On the other hand, when the processing system of S10 is selected in step S0, an AOD head is used as an optical head used for discriminating the optical disc when the optical disc is mounted on the information recording / reproducing apparatus. In addition, recording and / or reproduction of user information and the like is performed. In this example, applying the method to adjust the reproducing power Pr ₂ of the laser beam irradiated from the AOD head during disc discriminating (blue) for reproducing the identification information of the optical disc (the method of Example 1). Information on the maximum reproduction power Pr _2max that can be irradiated with the blue laser when reproducing the identification information of the optical disk is stored in advance in a memory or the like of the information recording / reproducing apparatus.

First, an optical disk is inserted into the information recording / reproducing apparatus (step S11). Next, the AOD head is driven to place the AOD head on the area (BCA) where the identification information of the optical disk is recorded (step S12). Next, the information of the maximum reproduction power Pr _2max that can be irradiated by the blue laser stored in the memory or the like of the information recording / reproducing apparatus is read, and the reproduction condition (blue laser reproduction power Pr ₂ ) at the time of discriminating the optical disk is set ( Step S13). At this time, the reproduction power Pr ₂ of the laser light irradiated from the AOD head is set to be equal to or less than the maximum reproduction power Pr _2max . Next, a laser beam having a predetermined reproduction power Pr ₂ that has been set is applied to the area where the identification information of the optical disk is recorded, and the identification information of the optical disk is reproduced based on the reflected light from the optical disk, and the type of optical disk (DVD Or AOD) is determined (step S14).

  If it is determined in step S14 that the optical disc loaded is AOD, the AOD head is placed at a predetermined position for recording and / or reproducing user information etc. of the optical disc, and the recording / reproducing condition of the AOD head is set to AOD. The recording / reproducing conditions used when recording and / or reproducing user information and the like are set (step S15). Next, the user information and the like are recorded and / or reproduced by irradiating a predetermined position of the optical disc with laser light (blue) under the recording / reproducing conditions set in step S15 (step S16).

  If it is determined in step S14 that the optical disk mounted is a DVD, the optical head is switched from the AOD head to the DVD head, and the DVD head is moved to a predetermined position for recording and / or reproducing user information on the optical disk. Arrange (step S17). Next, recording / reproduction conditions for the DVD head are set (step S18). Next, the laser beam (red) is irradiated to a predetermined position of the optical disc under the recording / reproducing conditions set in step S18 to record and / or reproduce user information or the like (step S19).

In the above applications, in determining the type of the optical disc in AOD head has been described a method of adjusting the reproduction power Pr ₂ of the laser beam from AOD head, as in Example 3-6, when the optical disc discriminating a method may be used to adjust the magnification of the spot area of the laser beam α is irradiated from the line velocity V ₂ or AOD head of the optical disk in the optical disk.

  In the first to sixth embodiments and the application examples, the method for discriminating between the DVD-R and the AOD has been described. However, the present invention is not limited to this, and the optical disc identification method of the present invention is not limited to the CD-R. The present invention can be similarly applied to the case where an optical disc is mounted on an information recording / reproducing apparatus, and the same effect can be obtained.

  In the first to sixth embodiments and the application examples, the method of individually including the DVD head and the AOD head has been described. However, the present invention is not limited to this, and the optical member such as the objective lens is shared and the laser light source is switched. Thus, a method of switching the spot diameter of the laser beam may be used. Also in this case, the same effects as those of the first to sixth embodiments and application examples can be obtained.

  In the optical disk identification method of the present invention, an optical head equipped with a blue laser can be discriminated, and even if the mounted optical disk is a red laser compatible optical disk such as a DVD, the optical disk is recorded. The optical disc can be discriminated without destroying the information. Therefore, when the optical disk mounted on the information recording / reproducing apparatus is an optical disk compatible with a blue laser such as AOD, the optical head is used when shifting from the determination operation of the optical disk to the recording and / or reproducing operation of user information and the like. Therefore, it is possible to reduce the time from the optical disc determination when the optical disc is inserted to the start of recording and / or reproduction of user information and the like. Therefore, in the future, when the frequency of use of the optical disk is increased in the optical disk compatible with the blue laser than the optical disk compatible with the red laser, the optical disk identification method of the present invention can record and / or reproduce user information from the optical disk determination. This is advantageous in terms of shortening the time to start. Therefore, the optical disk identification method of the present invention is a suitable identification method for the next-generation information recording / reproducing system in which the use frequency of large-capacity optical disks is expected to increase.

FIG. 1 is a diagram showing a change in amplitude of a reproduction signal with respect to a laser power when a DVD-R is irradiated with laser light by a DVD head. FIG. 2 is a schematic cross-sectional view of the AOD used in Example 1. FIG. 3 is a schematic cross-sectional view of the DVD-R used in Example 1. FIG. 4 is a flowchart showing a procedure for recording and reproducing information in the first embodiment. FIG. 5 is a diagram showing a change in amplitude of a reproduction signal with respect to laser power when a DVD-R is irradiated with laser light by an AOD head. FIG. 6 is an S-shaped curve when the focus of the laser beam is controlled in the fifth embodiment. FIG. 7 is a flowchart showing a procedure for recording / reproducing information in the recording / reproducing system of the application example.

Explanation of symbols

20 AOD
30 DVD-R

Claims (14)

A method of reproducing information including at least identification information recorded on an optical recording medium,
Irradiating a first optical recording medium on which information reproduction is performed by irradiating a first light beam having a predetermined spot size with a second light beam having a spot size smaller than the first light beam;
An information reproducing method for an optical recording medium, comprising: reproducing identification information of the first optical recording medium based on a second light beam from the first optical recording medium. When the first optical recording medium is irradiated with the first optical recording medium to reproduce information, the wavelength of the first optical beam is λ ₁ , the numerical aperture of the objective lens is NA ₁ and the linear velocity of the first optical recording medium is V _1. The maximum reproduction power of the first light beam under the reproduction condition is Pr _1max, and the second light beam is reproduced when the first optical recording medium is irradiated with the second optical beam to reproduce the identification information of the first optical recording medium. When the wavelength of the light beam is λ ₂ , the numerical aperture of the objective lens is NA ₂ , the linear velocity of the first optical recording medium is V _2, and the reproduction power of the second light beam is Pr ₂ ,
Pr ₂ ≦ {(λ ₂ NA ₁ ) / (λ ₁ NA ₂ )} ² Pr _1max (V ₂ / V ₁ ) ^1/2
The information reproducing method according to claim 1, wherein the reproduction power Pr ₂ of the second light beam is set so that the relationship is satisfied. When the first optical recording medium is irradiated with the first optical recording medium to reproduce information, the wavelength of the first optical beam is λ ₁ , the numerical aperture of the objective lens is NA ₁ and the linear velocity of the first optical recording medium is V _1. The maximum reproduction power of the first light beam under the reproduction condition is Pr _1max, and the second light beam is reproduced when the first optical recording medium is irradiated with the second optical beam to reproduce the identification information of the first optical recording medium. When the wavelength of the light beam is λ ₂ , the numerical aperture of the objective lens is NA ₂ , the linear velocity of the first optical recording medium is V _2, and the reproduction power of the second light beam is Pr ₂ ,
V ₂ ≧ {(λ ₁ NA ₂ ) / (λ ₂ NA ₁ )} ⁴ (Pr ₂ / Pr _1max ) ² V ₁
The information reproducing method according to claim 1, wherein the linear velocity V ₂ of the first optical recording medium is set so that the above relationship is satisfied. When the first optical recording medium is irradiated with the first light beam to reproduce information, the wavelength of the first light beam is λ ₁ and the numerical aperture of the objective lens is NA _1, and the maximum of the first light beam under the reproduction condition is the reproduction power is set to Pr _1max, also ₂ wavelength λ of the second light beam when reproducing the identification information of the first optical recording medium by irradiating a second light beam on the first optical recording _medium, the aperture of the objective lens When the number is NA ₂ , the reproduction power of the second light beam is Pr _2, and the magnification of the spot area of the second light beam irradiated onto the first optical recording medium with respect to the spot area at the time of focusing is α
α ≧ (Pr ₂ / Pr _1max ) {(λ ₁ NA ₂ ) / (λ ₂ NA ₁ )} ²
The information reproducing method according to claim 1, wherein an enlargement ratio α of the spot area of the second light beam is set so that the relationship is satisfied. The maximum reproduction power Pr _2max of the second light beam that can be applied to the first optical recording medium is measured in _advance , and the second optical beam is applied to the first optical recording medium to obtain identification information of the first optical recording medium. 2. The information reproducing method according to claim 1, wherein the reproducing power of the second light beam during reproduction is set to be equal to or less than the maximum reproducing power _Pr2max . The minimum value V _2min of the linear velocity of the first optical recording medium that can reproduce information by irradiating the second optical beam to the first optical recording medium is measured in advance, and the second optical beam is applied to the first optical recording medium. 2. The information reproducing method according to claim 1, wherein the linear velocity of the first optical recording medium when the identification information of the first optical recording medium is reproduced by irradiation is set to the minimum value _V2min or more. In advance, the minimum value α _min of the enlargement ratio with respect to the spot area at the time of in-focus of the spot area of the second light beam that can reproduce information by irradiating the first optical recording medium with the second light beam is measured in advance. The magnification ratio of the spot area of the second light beam when reproducing the identification information of the first optical recording medium by irradiating the first optical recording medium with the light beam is set to be equal to or greater than the minimum value α _min. 2. The information reproducing method according to claim 1, wherein An information recording / reproducing apparatus capable of mounting different types of optical recording media in which information is reproduced with light beams of different spot sizes, and reproducing the identification information recorded on the optical recording medium, thereby reproducing the type of the optical recording medium. A method for identifying
Irradiating an optical recording medium mounted on the information recording / reproducing apparatus with a second light beam having a smaller spot size than the first light beam having the maximum spot size among the light beams having different spot sizes;
A method for identifying an optical recording medium, comprising: reproducing identification information of the mounted optical recording medium. The wavelength of the first light beam when reproducing the information by irradiating the optical recording medium on which information is reproduced with the first light beam is λ ₁ , the numerical aperture of the objective lens is NA ₁ and the first light beam. And V ₁ is the linear velocity of the optical recording medium on which information reproduction is performed, Pr _1max is the maximum reproduction power of the first light beam under the reproduction conditions, and the second optical beam is applied to the mounted optical recording medium. The wavelength of the second light beam when reproducing the identification information of the mounted optical recording medium by irradiation is λ ₂ , the numerical aperture of the objective lens is NA ₂ , and the linear velocity of the mounted optical recording medium is V _2. When the reproduction power of the second light beam is Pr ₂ ,
Pr ₂ ≦ {(λ ₂ NA ₁ ) / (λ ₁ NA ₂ )} ² Pr _1max (V ₂ / V ₁ ) ^1/2
The identification method according to claim 8, wherein the reproduction power Pr ₂ of the second light beam is set so that the relationship is satisfied. The wavelength of the first light beam when reproducing the information by irradiating the optical recording medium on which information is reproduced with the first light beam is λ ₁ , the numerical aperture of the objective lens is NA ₁ and the first light beam. And V ₁ is the linear velocity of the optical recording medium on which information reproduction is performed, Pr _1max is the maximum reproduction power of the first light beam under the reproduction conditions, and the second optical beam is applied to the mounted optical recording medium. The wavelength of the second light beam when reproducing the identification information of the mounted optical recording medium by irradiation is λ ₂ , the numerical aperture of the objective lens is NA ₂ , and the linear velocity of the mounted optical recording medium is V _2. When the reproduction power of the second light beam is Pr ₂ ,
V ₂ ≧ {(λ ₁ NA ₂ ) / (λ ₂ NA ₁ )} ⁴ (Pr ₂ / Pr _1max ) ² V ₁
The identification method according to claim 8, wherein the linear velocity V ₂ of the mounted optical recording medium is set so that the above relationship is satisfied. When the optical recording medium on which information is reproduced by the first light beam is irradiated with the first light beam, the wavelength of the first light beam when reproducing the information is λ ₁ and the numerical aperture of the objective lens is NA _1, and the reproduction condition The maximum reproduction power of the first light beam below is Pr _1max, and the second light beam is reproduced when the attached optical recording medium is irradiated with the second optical beam to reproduce the identification information of the attached optical recording medium. When the wavelength of the light beam is λ ₂ , the numerical aperture of the objective lens is NA ₂ , the reproduction power of the second light beam is Pr _2, and the spot area of the second light beam irradiated on the mounted optical recording medium is in focus When the enlargement ratio with respect to the spot area is α,
α ≧ (Pr ₂ / Pr _1max ) {(λ ₁ NA ₂ ) / (λ ₂ NA ₁ )} ²
The identification method according to claim 8, wherein an enlargement ratio α of the spot area of the second light beam is set so that the relationship is satisfied. In advance, the maximum reproduction power Pr _2max of the second light beam that can be applied to the mounted optical recording medium is measured in advance, and the mounted optical recording medium is irradiated with the second light beam to mount the mounted light. _9. The identification method according to claim 8, wherein the reproduction power of the second light beam when reproducing the identification information of the recording medium is set to the maximum reproduction power _Pr2max or less. The minimum value V _2min of the linear velocity of the mounted optical recording medium that can reproduce information by irradiating the mounted optical recording medium with the second light beam is measured in advance, and the second light beam is mounted on the mounted optical recording medium. The linear velocity of the mounted optical recording medium when reproducing the identification information of the mounted optical recording medium by irradiating the optical recording medium is set to the minimum value V _{2 min} or more. Item 9. The identification method according to Item 8. Preliminarily measuring the minimum value α _min of the enlargement ratio of the spot area of the second light beam that can reproduce information by irradiating the mounted optical recording medium with the second light beam in advance, The expansion ratio of the spot area of the second light beam when reproducing the identification information of the mounted optical recording medium by irradiating the mounted optical recording medium with the second optical beam becomes the minimum value α _min or more. The identification method according to claim 8, wherein the identification method is set as follows.

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