JP2006079717A - Recording method, recording device and optical recording medium for barcode data of optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a barcode data recording method for an optical recording medium and a recording device that can record barcode data, such as BCA, with high precision and appropriate efficiency in the optical recording medium equipped with a recording layer with optical characteristics changed by irradiation of a laser beam with wavelength of 380-450 nm and a cover layer thinner than a substrate, and the optical recording medium on which the barcode data is recorded. <P>SOLUTION: On a translucent substrate 12, a recording layer 14 with optical characteristics changed by irradiation of the laser beam with wavelength of 380-450 nm and a translucent cover layer 16 thinner than a substrate 12 are formed. To an optical recording medium 10 constituted so that the data is recorded/reproduced by irradiation of the laser beam from a side of the cover layer 16, the barcode data is recorded on a recording layer 14 by applying the laser beam from the side of the substrate 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a recording method, a recording apparatus, and an optical recording medium for recording barcode data on an optical recording medium on which information is recorded by optically changing a recording layer when irradiated with laser light.

  Optical recording media such as CD (Compact Disc) and DVD (Digital Versatile Disc) are widely used as information recording media. Furthermore, in recent years, attention has been focused on optical recording media capable of recording information with higher density and larger capacity by using blue or blue-violet laser light having a wavelength of about 380 nm to 450 nm as irradiation light. In order to unify the specifications, blue-violet laser light having a wavelength of about 405 nm is used, the numerical aperture of the objective lens is set to 0.85 which is larger than that of DVD, and the cover layer is thinner than DVD. A proposal of 1 mm has been made, and an optical recording medium corresponding to this has been spreading.

  Here, in order to understand the present invention, the relationship among the numerical aperture of the objective lens, the focal length, the focal spot diameter, and the focal depth will be briefly described. The laser light is condensed by the objective lens and irradiated onto the recording layer of the optical recording medium. The smaller the numerical aperture of the objective lens, the longer the focal length. Further, the smaller the numerical aperture of the objective lens, the larger the focal spot diameter of the laser beam. Also, there is a region in the vicinity of the focal point where the variation of the spot diameter of the laser beam in the optical axis direction is small. The length of this region in the optical axis direction is called the focal depth, and the smaller the numerical aperture of the objective lens, the focal depth Is deep (long). Thus, in the vicinity of the focal point, since the fluctuation of the spot diameter of the laser beam in the optical axis direction is small and it is suitable for irradiating the laser beam with high energy density with high accuracy, the recording apparatus of the optical recording medium is a laser beam. Is set so that the focal point of the recording layer substantially coincides with the recording layer.

  By the way, optical recording media are broadly classified into ROM (Read Only Memory) type in which data cannot be additionally written or rewritten, R (Recordable) type in which data can be additionally written only once, and RW (Rewritable) type in which data can be rewritten. On the recording layer of an R-type or RW-type optical recording medium, barcode-like data called BCA (Burst Cutting Area) may be recorded for the purpose of copyright protection, for example (for example, patents) References 1 and 2). Each mark constituting the barcode data is a substantially rectangular shape that is long in the radial direction, and is formed at appropriate intervals in the circumferential direction by irradiating the optical recording medium with laser light. The marks constituting such bar code data are formed over a large number of tracks in the radial direction for the purpose of preventing falsification and the like. It is formed with a width of several tens to several thousand times. That is, each mark constituting the barcode data is provided with an objective lens that is significantly larger than a normal recording mark and has a numerical aperture smaller than that of a recording device for forming a normal recording mark. Recording is often performed by a dedicated recording device having a large spot diameter. As described above, by using a dedicated recording apparatus, it is possible to efficiently form barcode data.

Japanese Patent Laid-Open No. 2001-76345 Japanese Patent Laid-Open No. 10-233019

  However, when the recording layer is irradiated with laser light from an objective lens having a small numerical aperture and a long focal length through a thin cover layer of about 0.1 mm, a spot of the laser light on the recording layer 100 as shown in FIG. A difference between the diameter and the spot diameter of the laser beam on the surface of the cover layer 102 hardly occurs. Therefore, if there are scratches, foreign matter, etc. on the surface of the cover layer, there is a problem that marks reflecting these scratches, foreign matter, etc. are easily formed, and the accuracy of forming barcode data is low.

  On the other hand, when laser light is irradiated from an objective lens having a large numerical aperture and a short focal length, the spot diameter of the laser light on the recording layer 100 and the laser on the surface of the cover layer 102 as shown in FIG. The difference between the spot diameter of the light and the surface of the cover layer, even if there are scratches or foreign objects, makes it difficult for the marks or foreign objects to be reflected on the mark, resulting in high accuracy of barcode data. However, the shorter the focal distance, the smaller the focal spot diameter of the laser light, and thus there is a problem that the efficiency of forming barcode data is low.

  In addition, since an objective lens with a large numerical aperture has a shallow depth of focus (short), in order to suppress fluctuations in the spot diameter and energy density of the laser beam in the recording layer, it is necessary to adjust the position of the objective lens so precisely. There is a problem.

  The present invention has been made in view of the above problems, and an optical recording comprising a recording layer whose optical properties change when irradiated with laser light having a wavelength of 380 to 450 nm and a cover layer thinner than the substrate. Barcode data recording method for optical recording medium capable of efficiently and efficiently recording barcode data such as BCA on the medium, recording apparatus, and optical recording medium on which barcode data is efficiently recorded with high accuracy The purpose is to provide.

  The present invention realizes recording of barcode data on a recording layer with high accuracy and efficiency by irradiating a laser beam from the side of the substrate having translucency and thicker than the cover layer. .

  By irradiating the laser beam from the substrate side thicker than the cover layer in this way, the spot diameter of the laser beam on the recording layer and the laser beam on the surface of the substrate can be obtained even with an objective lens having a small numerical aperture and a long focal length. Since the difference between the spot diameter and the surface of the substrate becomes large, even if scratches or foreign matter exist on the surface of the substrate, these scratches or foreign matter are not easily reflected on the mark, and barcode data is formed with high accuracy. be able to. Further, if an objective lens having a small numerical aperture is used, the spot diameter of the focal point of the laser beam is increased accordingly, so that barcode data can be formed efficiently.

  That is, the above object can be achieved by the following invention.

(1) A recording layer whose optical characteristics are changed by irradiating a laser beam having a wavelength of 380 to 450 nm on a light-transmitting substrate, a light-transmitting cover layer that is thinner than the substrate, And an optical recording medium configured to record / reproduce data by irradiating a laser beam from the cover layer side so that the substrate faces the optical head unit, and the substrate A bar code data recording method for an optical recording medium, wherein bar code data is formed on the recording layer by irradiating a laser beam from the side.

(2) In (1), the laser beam is condensed by an objective lens having a numerical aperture of 0.05 to 0.15 and irradiated onto the recording layer. Data recording method.

(3) A recording layer whose optical characteristics are changed by irradiating laser light having a wavelength of 380 to 450 nm on a light-transmitting substrate, and a light-transmitting cover layer having a lighter thickness than the substrate. An optical recording medium holding unit for holding an optical recording medium formed and configured to record / reproduce data when irradiated with laser light from the cover layer side, a laser light oscillation unit, and an objective lens And an optical head unit for irradiating the optical recording medium held by the optical recording medium holding unit with a laser beam from the substrate side so that the focal point coincides with the recording layer. A bar code data recording apparatus for an optical recording medium.

(4) The barcode data recording apparatus for an optical recording medium according to (3), wherein the objective lens of the optical head section has a numerical aperture in the range of 0.05 to 0.15.

(5) A recording layer whose optical characteristics change when irradiated with laser light having a wavelength of 380 to 450 nm on a light-transmitting substrate, a light-transmitting cover layer that is thinner than the substrate, The light transmittance from the surface opposite to the side irradiated with the laser beam to the recording layer is in the range of 20 to 95%, and the recording layer is irradiated with the laser beam from the substrate side. An optical recording medium characterized in that bar code data is formed on the recording layer.

  According to the present invention, barcode data such as BCA can be efficiently recorded with high accuracy on an optical recording medium having a thin cover layer of, for example, about 0.1 mm.

  Hereinafter, preferred embodiments for carrying out the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, the optical recording medium 10 according to the present embodiment has a recording layer whose optical characteristics change when a translucent substrate 12 is irradiated with laser light having a wavelength of 380 to 450 nm. 14 and a cover layer 16 having translucency and thinner than the substrate 12 are formed, and light is transmitted from the surface of the optical recording medium 10 opposite to the side irradiated with the laser light to the recording layer 14. The rate is in the range of 20 to 95%, and the recording layer 14 is irradiated with laser light from the substrate 12 side to form the barcode data 17 as shown in FIG. .

  The optical recording medium 10 is a disc-shaped R-type or RW-type optical disc having an outer diameter of about 120 mm and a thickness of about 1.2 mm.

  The substrate 12 has a thickness of about 1.1 mm, and a groove constituting a track for forming a recording mark is formed on the surface on the recording layer 14 side. As a material of the substrate 12, a light-transmitting polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin, polyethylene resin, polypropylene resin, silicone resin, fluorine resin, ABS resin, urethane resin, or the like can be used.

  The recording layer 14 is formed in a concavo-convex pattern following the concavo-convex pattern of the substrate 12. In the case of the R type, the recording layer 14 can be made of an inorganic material such as an organic dye or a metal oxide. In the case of the R type, a reflective layer and a dielectric layer are formed adjacent to the recording layer 14 as necessary. In the case of the RW type, a phase change material can be used as the material of the recording layer 14. Also in the case of the RW type, a reflective layer and a dielectric layer are formed adjacent to the recording layer 14 as necessary. When the reflective layer is formed between the recording layer 14 and the substrate 12 side, the material, thickness, etc. of the reflective layer so that the light transmittance from the surface of the substrate 12 to the recording layer 14 is 20 to 95%. Adjust. As the material of the reflective layer, for example, a dielectric material having a high reflectance can be used. In this case, the reflective layer can also be configured to double as a dielectric layer.

  The cover layer 16 has a thickness of about 0.1 mm. As a material for the cover layer 16, energy ray curable resin such as translucent acrylic ultraviolet curable resin and epoxy ultraviolet curable resin can be used. Here, the term “energy beam” is used to mean a general term for electromagnetic waves such as ultraviolet rays and electron beams, and particle beams, which have the property of curing a specific resin in a fluid state. In addition, as a material for the cover layer 16, a light-transmitting film may be used.

  The barcode data 17 is formed in a part of the optical recording medium 10 near the inner periphery, for example. Each mark 17A constituting the barcode data 17 is a substantially rectangular shape that is long in the radial direction, is formed across a large number of tracks in the radial direction, and is also the circumferential length of a normal recording mark in the circumferential direction. The width is several tens to several thousand times the width.

  The barcode data 17 is formed on the optical recording medium 10 using a barcode data recording device 18 as shown in FIG.

  The bar code data recording device 18 includes an optical recording medium holding unit 20 for holding the optical recording medium 10, a laser beam oscillation unit 22, and an objective lens 24, and is held by the optical recording medium holding unit 20. The optical recording medium 10 is provided with an optical head unit 26 for irradiating laser light so that the focal point coincides with the recording layer 14 from the substrate 12 side.

  The optical recording medium holding unit 20 includes an attachment / detachment mechanism (not shown) for detachably holding the optical recording medium 10 and is rotatably attached to the motor 28. The motor 28 is attached to the base portion 30. A motor control unit 32 is connected to the motor 28, and the motor control unit 32 is connected to the main control unit 34.

  The laser light oscillation unit 22 of the optical head unit 26 is configured to oscillate laser light having a wavelength of about 780 nm. The optical head unit 26 is attached to the base unit 30 via a carriage motor 36 so that a desired portion of the recording layer 14 can be irradiated with laser light. In addition, a laser output control unit 38 is connected to the optical head unit 26, and the laser output control unit 38 is connected to the main control unit 34. The carriage motor 36 is also connected to the main control unit 34.

  The objective lens 24 has a numerical aperture smaller than the numerical aperture 0.85 of the objective lens for recording normal data, and the focal point is on the recording layer 14 of the optical recording medium 10 held by the optical recording medium holding unit 20. It is installed so that it almost matches. The numerical aperture of the objective lens 24 is preferably in the range of 0.05 to 0.15.

  Next, a method of recording the barcode data 17 on the optical recording medium 10 using the barcode data recording device 18 will be described with reference to the flowchart of FIG.

  First, the optical recording medium 10 is held by the optical recording medium holding unit 20 so that the substrate 12 faces the optical head unit 26 (S202).

  Next, while rotating the optical recording medium 10 together with the optical recording medium holding unit 20, the position of the optical head unit 26 is adjusted to irradiate the optical recording medium 10 with laser light from the substrate 12 side. Each mark 17A constituting the bar code data 17 is formed (recorded) at the site (S204).

  Since the numerical aperture of the objective lens 24 is smaller than the numerical aperture 0.85 of the objective lens for recording normal data, the barcode data recording device 18 records normal data with the spot diameter of the focal point of the laser beam. It is larger than the spot diameter of the focal point of the laser beam. Therefore, each mark 17A constituting the barcode-like data 17 such as BCA (which is significantly larger than the recording mark of normal data) can be efficiently formed.

  The relationship between the wavelength λ of the laser beam and the numerical aperture NA of the objective lens 24 and the focal spot diameter φ of the laser beam is expressed by the following equation (I).

  φ = 0.82 × λ / NA (I)

  The relationship between the wavelength λ of the laser beam and the numerical aperture NA of the objective lens 24 and the focal depth D of the laser beam is expressed by the following equation (II).

D = λ / (NA) ² (II)

  The spot shape of the focal point of the laser beam is almost circular, and when the spot diameter is shorter than the width of each mark 17A constituting the barcode information (the length in the radial direction of the disk), the optical head portion 26 A mark having a desired length can be formed by repeating the laser light irradiation a plurality of times while shifting the position in the radial direction.

  Further, since the optical recording medium 10 is rotated together with the optical recording medium holding unit 20, the length (circumferential width) of the mark can be adjusted by adjusting the irradiation time of the laser beam, and the irradiation time. The longer the length, the wider the mark can be formed.

  Since the barcode data recording apparatus 18 irradiates laser light from the side of the substrate 12 that is thicker than the cover layer 16, even if the numerical aperture of the objective lens 24 is small and the focal length of the laser light is long, the laser in the recording layer 14 is used. The difference between the spot diameter of light and the spot diameter of laser light on the surface of the substrate 12 is large. Therefore, even if there are scratches or foreign matter on the surface of the substrate 12, these scratches or foreign matter are not easily reflected on the mark, and the barcode data 17 can be formed with high accuracy.

  Further, since the numerical data recording device 18 has a small numerical aperture of the objective lens 24, the focal depth of the laser beam is deep (long), and it is constant without adjusting the installation position of the objective lens 24 or the like with high accuracy. The recording layer 14 can be irradiated with a laser beam having a spot diameter as described above, and the barcode data 17 can be formed with high accuracy in this respect.

  That is, the barcode data recording device 18 can efficiently record the barcode data 17 such as BCA on the optical recording medium 10 having the thin cover layer 16 of 0.1 mm with high accuracy.

  Further, since the optical recording medium 10 has a light transmittance of 20 to 95% from the surface of the substrate 12 opposite to the substrate 12 to the recording layer 14, the laser light from the optical head unit 26 is applied to the recording layer 14. Irradiated efficiently, the barcode data 17 can be recorded with high accuracy and efficiency.

  Table 1 shows the relationship among the numerical aperture of the objective lens 24, the depth of focus, the spot diameter of the laser light in the recording layer 14 and the spot diameter of the surface of the substrate 12 when the wavelength of the laser light is 780 nm. Show. Further, when the laser light is irradiated from the cover layer 16 side so that the focal point coincides with the recording layer 14 (the recording layer is located in a portion within the range of the focal depth where the focal point is best), the surface of the cover layer 16 The spot diameter is also shown in Table 1.

  From Table 1, when the numerical aperture of the objective lens 24 is 0.025, the surface of the cover layer 16 and the substrate 12 can be irradiated by laser light from the cover layer 16 side or laser light from the substrate 12 side. The spot diameter of the laser beam at is equal to the spot diameter of the laser beam at the recording layer 14, and if there are scratches or foreign matter on the surface of the cover layer 16 or the substrate 12, a mark reflecting these scratches or foreign matter is present. Presumed to be easily formed.

  On the other hand, when the numerical aperture of the objective lens 24 is 0.04, the laser light on the surface of the cover layer 16 when the laser light is irradiated from the cover layer 16 side so that the focal point of the recording layer 14 coincides. The spot diameter of the laser beam on the surface of the substrate 12 when the laser beam is irradiated from the substrate 12 side is about 1.8 times the spot diameter, and the cover layer 16 is irradiated by irradiating the laser beam from the substrate 12 side. In contrast to the case where the laser beam is irradiated from the side, it is presumed that a certain effect can be obtained in which the influence of the surface scratches, foreign matters, etc. on the mark can be suppressed.

  Further, if the numerical aperture of the objective lens 24 is 0.05 or more, the laser beam spot on the surface of the cover layer 16 when the laser beam is irradiated from the cover layer 16 side so that the focal point of the recording layer 14 coincides. When the laser beam is irradiated from the substrate 12 side, the spot diameter of the laser beam on the surface of the substrate 12 is about 3 to 10 times, and by irradiating the laser beam from the substrate 12 side, the cover layer 16 side It is considered that the influence on the mark due to surface scratches or foreign matters can be greatly suppressed in comparison with the case where the laser beam is irradiated from above.

  When the numerical aperture of the objective lens 24 is 0.3 or more, since the spot diameter in the recording layer is too small, there is a concern that the recording efficiency of the barcode data 17 may be greatly reduced, and the depth of focus is too small. Therefore, in order to irradiate the recording layer 14 with laser light having a constant spot diameter, it is necessary to precisely adjust the installation position of the objective lens.

  On the other hand, if the numerical aperture of the objective lens 24 is 0.15 or less, a sufficient spot diameter and a sufficient depth of focus can be obtained in the recording layer, and the barcode data 17 can be formed efficiently and with high accuracy. Can do.

  That is, it can be seen from Table 1 that when the wavelength of the laser beam is about 780 nm, the numerical aperture of the objective lens 24 is preferably in the range of 0.05 to 0.15. In addition, the barcode data recording apparatus is required by the standard to set the (focus) spot diameter in the laser light recording layer to 10 ± 5 μm, but when using laser light having a wavelength of about 780 nm. When the numerical aperture of the objective lens 24 is in the range of 0.05 to 0.15, it can be seen that this requirement is satisfied.

  In this embodiment, the barcode data recording device 18 is configured to oscillate laser light having a wavelength of about 780 nm. However, the type of the recording layer 14 and each mark of the barcode data 17 to be formed are The wavelength of the laser beam to be oscillated may be appropriately determined according to the size of 17A.

  In this embodiment, the recording layer 14 of the optical recording medium 10 has a configuration in which the optical characteristics change when irradiated with laser light having a wavelength of 405 nm, but is irradiated with laser light having a wavelength of 380 to 450 nm. Therefore, the present invention can be applied to any optical recording medium having a recording layer whose optical characteristics change. In particular, laser light focused by an objective lens having a wavelength of 380 to 450 nm and a numerical aperture NA of 0.7 to 0.9 is applied to the recording layer through a cover layer thinner than the substrate to record data. The present invention is suitable for an optical recording medium configured to perform reproduction.

  In this embodiment, the barcode data 17 is formed using a laser beam having a circular spot shape. However, the barcode data is formed using a laser beam having an elongated, substantially rectangular spot shape. Is also possible.

  In the present embodiment, the optical recording medium 10 has only one recording layer 14 formed on one side of the substrate 12, but the recording layer 14 is provided on one side of the substrate 12 through a light-transmitting spacer layer. Two or more layers can be formed. In this case, the barcode data 17 may be formed on a part of the plurality of recording layers 14 or may be formed on all the recording layers 14. The light transmittance from the surface 12 to the recording layer 14 on which the barcode information 17 is formed is preferably in the range of 20 to 95%.

  In this embodiment, the optical recording medium 10 has an outer diameter of about 120 mm and a thickness of about 1.2 mm, the substrate 12 has a thickness of 1.1 mm, and the cover layer 16 has a thickness of 0.1 mm. However, these dimensions may be changed as necessary. For example, the thickness of the cover layer 16 may be appropriately changed within a range of about 30 to 200 μm. When two or more recording layers 14 are formed on one side of the substrate 12 through the spacer layer as described above, the thickness of the cover layer 16 is reduced by the thickness of the spacer layer, so that the optical recording medium 10 The thickness of can be 1.2 mm.

  In this embodiment, the optical recording medium 10 is a single-sided recording type capable of recording information on only one side, but it is also applicable to a double-sided recording type optical recording medium in which a recording layer and a cover layer are formed on both sides. The present invention is naturally applicable. Also in this case, if each recording layer is irradiated with laser light from the substrate side, barcode data such as BCA can be recorded with high accuracy and efficiency. In this case, even if the recording layer on either side is irradiated with the laser beam, the recording layer is irradiated with the laser beam from the substrate side via the other side cover layer or recording layer. In this case, “irradiating the recording layer with laser light from the substrate side” means that the recording layer is irradiated with laser light from the substrate side opposite to the cover layer covering the recording layer. In the case where the recording layer is irradiated with laser light from the substrate side through the cover layer and recording layer on the other side as in the example of laser light irradiation to the recording optical recording medium, “recording from the substrate side” Needless to say, it is included in “irradiating a layer with laser light”.

  In the present embodiment, the optical recording medium 10 is an optical disk, and the barcode data recording apparatus 18 forms a mark on the optical recording medium 10 only by the optical head unit 26, but in addition to the optical head 22. Further, a magnetic head may be provided, and barcode data such as BCA may be recorded on a magneto-optical disk such as MD or MO. Also in this case, it is possible to efficiently form barcode data with high accuracy.

  The present invention can be used to record bar code information such as BCA on an optical recording medium.

1 is a side sectional view schematically showing a schematic structure of an optical recording medium according to an embodiment of the present invention. Flat sectional view schematically showing the configuration of barcode data formed on the same optical recording medium Side view schematically showing a schematic structure of a barcode data recording apparatus for forming the barcode data The flowchart which shows the recording method of the barcode data Side view schematically showing how laser light is focused by a conventional objective lens having a large numerical aperture Side view schematically showing how laser light is focused by a conventional objective lens having a small numerical aperture

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Optical recording medium 12 ... Substrate 14 ... Recording layer 16 ... Cover layer 17 ... Bar code-like data 17A ... Mark 18 ... Bar code-like data recording device 20 ... Optical recording medium holding part 22 ... Laser beam oscillation part 24 ... Objective lens 26: Optical head

Claims (3)

  A recording layer whose optical characteristics change when irradiated with laser light having a wavelength of 380 to 450 nm and a cover layer that is translucent and thinner than the substrate are formed on a light-transmitting substrate. An optical recording medium configured to record / reproduce data by irradiating a laser beam from the cover layer side is disposed so that the substrate faces the optical head portion, and the laser is emitted from the substrate side. A bar code data recording method for an optical recording medium, wherein bar code data is formed on the recording layer by irradiating light.   On the substrate having translucency, a recording layer whose optical characteristics are changed by irradiation with laser light having a wavelength of 380 to 450 nm, and a cover layer having translucency and thinner than the substrate are formed, An optical recording medium holding unit for holding an optical recording medium configured to record / reproduce data when irradiated with laser light from the cover layer side; a laser light oscillation unit; and an objective lens And an optical head unit for irradiating the optical recording medium held by the optical recording medium holding unit from the substrate side with a laser beam so that the focal point coincides with the recording layer. An optical recording medium barcode data recording apparatus.   A recording layer whose optical characteristics change when irradiated with laser light having a wavelength of 380 to 450 nm and a cover layer that is translucent and thinner than the substrate are formed on a light-transmitting substrate. The light transmittance from the surface opposite to the side irradiated with the laser beam to the recording layer is in the range of 20 to 95%, and the recording layer is irradiated with the laser beam from the substrate side to perform the recording. An optical recording medium characterized in that barcode data is formed on a layer.

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