JP4525604B2 - Information recording method, multilayer optical recording control device, and information recording device - Google Patents

Description

  The present invention relates to an information recording method for a multilayer optical recording medium in which a plurality of information recording layers are laminated, and a control apparatus and an information recording apparatus for executing the information recording method.

  Conventionally, CDs and DVDs are widely used as optical recording media. The recording capacity required for this type of optical recording medium has been increasing year by year, and various proposals have been made to meet the demand. For example, in a read-only optical recording medium such as a DVD-Video or a DVD-ROM, an information recording layer having a two-layer structure with an increased recording capacity has been put into practical use.

  As in the DVD shown in FIG. 10, pits are formed on each of the two substrates to form an information recording layer, and the two substrates are pasted with a spacer layer interposed therebetween with the information recording layer facing each other. Optical recording media having a combined structure have been put into practical use.

  Further, as shown in FIG. 11, a hybrid structure DVD in which one information recording layer is formatted in the DVD format and the other information recording layer is formatted in the CD format has been put into practical use. In this case, for the purpose of adapting to each standard, the information recording layer that is a DVD format is set to 0.6 mm from the light incident surface and has a capacity of 4.7 GB, and the information that becomes a CD format is used. The recording layer is set to 1.2 mm from the light incident surface and has a capacity of 0.7 GB. In order to reproduce the signal recorded on each information recording layer, two types of optical systems having different wavelengths and numerical apertures (NA) are required.

  In recent years, a new standard such as a Blu-ray disc has been proposed in order to further increase the recording capacity. In the Blu-ray disc, an information recording layer is laminated in the vicinity of 0.1 mm from the light incident surface, and 25 GB of information can be recorded on this information recording layer. For example, in the case of a two-layer Blu-ray disc, one information recording layer is formed at a position 0.075 mm from the light incident surface, and the other information recording layer is formed at a position 0.1 mm from the light incident surface.

  In a large-capacity optical recording medium, it is required to reduce the beam spot diameter of laser light used for data recording / reproduction. For this purpose, it is necessary to increase the numerical aperture (NA) of the objective lens for focusing the laser light and shorten the wavelength λ of the laser light.

However, when the numerical aperture of the objective lens is increased, there arises a problem that the tilt margin of the laser beam with respect to the optical recording medium, that is, the tolerance of the tilt angle error of the optical axis with respect to the optical recording medium becomes very small. On the other hand, when the distance from the light incident surface of the optical recording medium to the information recording layer is reduced, the tilt margin is increased. Therefore, in order to prevent the tilt margin from being reduced while increasing the numerical aperture of the objective lens, the distance from the light incident surface to the information recording layer (that is, the thickness of the light transmission layer) is reduced. Is effective. Therefore, in the Blu-ray disc, the thickness of the light transmission layer is set to about 100 μm.
Japanese Patent No. 3206748 Japanese Patent No. 3210549

  However, when the information recording layer is formed near the light incident surface by setting the light transmitting layer to be thin like a Blu-ray disc, fingerprints and dust may adversely affect information recording / reproduction. There was a problem that it was easy to give. For example, when an information recording layer is further added to the Blu-ray Disc standard, it is necessary to dispose the information recording layer within a distance of 0.1 mm from the light incident surface. It will be easy to be affected. The analysis results of the present inventors (unknown at the time of the present application) conducted to clarify this influence are shown in FIG. In this analysis, the distance of the information recording layer of the optical recording medium is changed, and the change in the bit error rate (bER) due to the presence or absence of foreign matters such as fingerprints is examined. As the foreign matter to be attached to the optical recording medium, an artificial fingerprint, which will be described later in detail in [Example], was used. The distance from the light incident surface to the light incident side information recording layer was adjusted by changing the thickness of the cover layer, and the recording capacities of the information recording layers were all matched. The thickness of the information recording layer is 48 nm, the composition is bismuth (Bi), oxygen (O), germanium (Ge), and the composition ratio (atm%) is Bi: O: Ge = 23: 68. : 9 was set. The bER is a ratio of the number of error bits to a predetermined number of bits, and it can be understood how many errors are included in the digital signal information to be reproduced. In general, when the bER is 10-3 or more, error correction becomes difficult even if the signal has redundancy.

  As is clear from FIG. 12, when the distance from the light incident surface to the information recording layer is within 75 μm, particularly within 65 μm, the bER greatly increases due to the influence of fingerprint attachment, and it is likely that it exceeds 10-3. It became clear.

  In particular, when information is recorded with a fingerprint or the like attached to the light incident surface, there is a problem that the recording mark is not completed and the reproduction quality of the signal is deteriorated. For example, as a technique to solve this, it is conceivable to inspect the surface of the disc before the start of recording. However, this method requires a long time from when the disc is inserted until recording is actually started. There was a problem of giving discomfort to the person.

  The present invention has been made in view of the above-described problems, and provides an information recording method and the like capable of recording information reliably and at high speed even when surface defects such as fingerprints exist in a multilayer optical recording medium. The purpose is to do.

In order to achieve the above object, the present invention, which has been made through intensive research by the present researchers, is an information recording method for recording information on a multi-layer optical recording medium having a plurality of information recording layers. Information is recorded by irradiating a recording laser beam to the first information recording layer set with a distance from the surface being larger than 65 μm, and the reflected light of the recording laser beam is detected to detect defect information of the multilayer optical recording medium The second information recording layer in which the distance from the light incident surface is set to 65 μm or less according to the level of the defect information regardless of whether or not the first information recording layer becomes a defect area. And recording information by irradiating the second information recording layer with a recording laser beam while avoiding the defective area. It is.

  The inventors focused on the fact that the surface defect of the multilayer optical recording medium can be detected by utilizing the reflected light (return light) of the recording laser light while recording information on the first information recording layer. As a result, since it is possible to record the second information recording layer while recognizing the surface defect state in advance, information recording errors in the second information recording layer can be reduced, and the reproduced signal after recording can be reduced. Quality can be improved. In addition, since it is not necessary to separately secure a time for inspecting the surface defect, the information recording start operation can be shortened, and the entire recording time can be shortened.

  In the above invention, defect information and non-defect areas of the multilayer optical recording medium are discriminated in advance using the defect information, and information recording by the recording laser beam is performed on the defect areas of the second information recording layer. Is preferably avoided. As a result, it is possible to avoid a state in which a recording mark is not sufficiently formed due to a surface defect or the like, so that information is reliably recorded.

  In the above invention, it is preferable to select an information recording layer having a distance from the light incident surface of the multilayer optical recording medium that is more distant than the second information recording layer as the first information recording layer. At the time of recording on the first information recording layer, the defect area cannot be grasped in advance. However, if an information recording layer separated from the light incident surface is selected as the first information recording layer, the first information recording layer is originally used. This is because the influence of surface defects in the recording operation can be reduced. That is, the recording operation of the first information recording layer that is resistant to surface defects can be effectively used as a recording preparation for the second information recording layer that is easily affected by surface defects.

  Furthermore, in the above invention, it is preferable to select an information recording layer having the longest distance from the light incident surface of the multilayer optical recording medium as the first information recording layer. Preferably, an information recording layer having the shortest distance from the light incident surface of the multilayer optical recording medium is selected as the second information recording layer.

  In the above invention, it is preferable to select a suitable second information recording layer from among a plurality of information recording layers using the level of defect information, and in this way, when there are many surface defects, By avoiding the use of the information recording layer closest to the incident surface itself, it is possible to perform the recording operation using the information recording layer far from the light incident surface as the second information recording layer. On the other hand, when there are few surface defects, information can be recorded actively using an information recording layer close to the light incident surface. Thus, if the information recording layer can be flexibly selected from a plurality of information recording layers, the recording efficiency can be further improved.

  Moreover, in the said invention, when it is judged that the said multilayer optical recording medium was taken out outside, it is preferable to initialize the said defect information. This is because even if the same medium is taken out, a new surface defect may be generated.

  Furthermore, in the above invention, when it is determined that the information recording on the first information recording layer has reached a predetermined amount, it is preferable to shift to the information recording action on the second information recording layer. Since the recording capacity (recording area) of the first information recording layer is physically limited, defect information cannot be collected in the same area if a large number of recording areas are used in one recording operation. End up. Therefore, as in the present invention, by setting an upper limit for the information recording operation for the first information recording layer, information is actively recorded in the multilayer direction for the inspected area. In other words, the information recording layer can be effectively used by recording information in the multi-layer direction after the purpose of inspecting the surface defect is achieved, rather than recording a plurality of information recording layers one by one. become. Further, the multilayer optical recording medium is in a clean state at the initial use of the disc, and it is highly possible that the contamination increases as the usage time becomes longer. However, defect information detected at the time of information recording on the first information recording layer is high. When the level is low, the predetermined amount is set to be small so that the second information recording layer can be transferred to the second information recording layer at an early stage, and information can be recorded including areas other than those already inspected. On the other hand, when the level of defect information is high, a large predetermined amount is set to secure a large inspected area, and information can be recorded on the second information recording layer only in the inspected area. Become.

  In the above invention, it is preferable that a recording area or an information recording amount is preset as the predetermined amount. More preferably, the information recording time is set in advance as the predetermined amount. Moreover, it is preferable that the information recording area of the second information recording layer is overlapped in the thickness direction with respect to the information recording area of the first information recording layer by the recording laser beam. In this way, the area where defect information is collected and the recording area for the second information recording layer can be reliably matched, so that the reliability of information recording can be further improved.

  Furthermore, in the above invention, it is preferable that the first information recording layer is a rewritable type in which recorded information can be erased and recorded again.

The present invention made to achieve the above object is a multi-layer optical recording control device used in an information recording apparatus for recording information on a multi-layer optical recording medium having a plurality of information recording layers. Defect information of the multilayer optical recording medium by detecting reflected light of the recording laser light when recording information by irradiating the first information recording layer whose distance from the surface is set to be larger than 65 μm with recording laser light The distance from the light incident surface depends on the level of the defect information in the defect information collection unit regardless of whether the first information recording layer is a defect region or not. A defect area setting unit for setting a defect area and a non-defect area of the second information recording layer set to 65 μm or less, and an information writing instruction for instructing recording of information on the second information recording layer while avoiding the defect area Part And a control device for multilayer optical recording.

  The present invention, which has been made to achieve the above object, includes the above multilayer optical recording control device, a laser light source for generating the recording laser light, a laser controller for controlling the laser light source, and the recording laser light. An information recording apparatus for a multilayer optical recording medium, comprising: an optical mechanism that guides the multilayer optical recording medium; and a light detection device that detects reflected light of the recording laser light and provides information to the control device. It is.

  According to the information recording method and the like of the present invention, even when a defect such as a fingerprint exists on the surface of the multilayer optical recording medium, it is possible to reduce the deterioration of information recording characteristics without requiring a special inspection time. An excellent effect can be achieved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, a multilayer optical recording medium 1 used in an information recording apparatus according to an embodiment of the present invention will be described with reference to FIG. The multilayer optical recording medium 1 is a disk-shaped medium having an outer diameter of about 120 mm and a thickness of about 1.2 mm. 1B, the multilayer optical recording medium 1 includes a substrate 10, an L0 information recording layer 20, a first spacer layer 30, an L1 information recording layer 22, and a second spacer layer. 32, the L2 information recording layer 24, the third spacer layer 34, the L3 information recording layer 26, the cover layer 36, and the hard coat layer 38 are laminated in this order.

  The first to third spacer layers 30, 32, 34, the cover layer 36, and the hard coat layer 38 are all light transmissive and transmit laser light incident from the outside. As a result, if the laser beam Z incident from the light incident surface 38A of the hard coat layer 38 is used, information can be recorded / reproduced on all of the L0 to L3 information recording layers 20, 22, 24, 26, and 28. ing.

  The L0 information recording layer 20 is the light incident side information recording layer farthest from the light incident surface 38A, and the L3 information recording layer 26 is the light incident side information recording layer closest to the light incident surface 38A. When recording / reproducing information to / from the L0 information recording layer 20, the L0 information recording layer 20 is irradiated with the laser beam Z through the L1 to L3 information recording layers 22, 24, and 26. Similarly, when information is recorded / reproduced with respect to the L1 information recording layer 22, the L1 information recording layer 22 is irradiated with the laser beam Z2 via the L2 and L3 information recording layers 24 and 26. When recording / reproducing information to / from the L2 information recording layer 24, the L2 information recording layer 24 is irradiated with laser light through the L3 information recording layer 26. When recording / reproducing information to / from the L3 information recording layer 26, the L3 information recording layer 26 is directly irradiated with the laser beam Z without passing through another information recording layer. In this multilayer optical recording medium 1, all the recording capacities of the L0 to L3 information recording layers 20, 22, 24, and 26 are set to 25 GB, and a recording capacity of 100 GB is ensured as a whole.

  The substrate 10 is a disk-shaped member having a thickness of about 1.1 mm, and various materials such as glass, ceramics, and resin can be used as the material. Here, polycarbonate resin is used. In addition to the polycarbonate resin, an olefin resin, an acrylic resin, an epoxy resin, a polystyrene resin, a polyethylene resin, a polypropylene resin, a silicone resin, a fluorine resin, an ABS resin, a urethane resin, or the like can be used as the resin. Of these, polycarbonate resins and olefin resins are preferred because of their ease of processing and molding. Further, grooves, lands, pit rows, and the like are formed on the surface of the substrate 10 on the information recording layer side according to applications.

  The first to third spacer layers 30, 32, and 34 are stacked between the L0 to L3 information recording layers 20, 22, 24, and 26, and between the information recording layers 20, 22, 24, and 26, respectively. Has the function of separating. Grooves (lands), pit rows, and the like are formed on the light incident surface 38A side surface of each spacer layer 30, 32, 34. Various materials can be used for the first to third spacer layers 30, 32, and 34. However, as described above, in order to transmit the laser beam Z, it is necessary to use a light transmissive material. For example, it is also preferable to use an ultraviolet curable acrylic resin.

  In the multilayer optical recording medium 1, the thickness of the first spacer layer 30 is set to 17 μm, the thickness of the second spacer layer 32 is set to 20 μm, and the thickness of the third spacer layer 34 is set to 13 μm. Thus, by making the thicknesses of the spacer layers 30, 32, and 34 different from each other, interference of the reproduction signal can be reduced, and noise of the read signal can be reduced. The hard coat layer 38 has a thickness of 2 μm, and the cover layer 36 has a thickness of 48 μm.

  Therefore, in this multilayer optical recording medium 1, the distance from the light incident surface 38A to the L3 information recording layer 26 is about 50 μm, the distance from the light incident surface 38A to the L2 information recording layer 24 is about 63 μm, and the light incident surface 38A to L1. The distance to the information recording layer 22 is about 83 μm, and the distance from the light incident surface 38A to the L0 information recording layer 20 is about 100 μm. The L0 information recording layer 20 is matched to the Blu-ray Disc standard including the recording capacity (25 GB).

  These L0 to L3 information recording layers 20, 22, 24, and 26 are layers for holding data. As a data holding form, a so-called recording type in which writing by a user is possible. In the case of this recording type, in detail, there are a write-once type in which data cannot be written again in the area where data has been written once, and a rewritable type in which data can be erased and written again in the area where data has been written. However, either may be used. In the information recording layers 20, 22, 24, and 26, the data holding modes can be different from each other. In particular, the L0 information recording layer 20 is desirably a rewritable type that can be erased once, and can be used again for medium surface inspection, as will be described later.

  Further, as shown in FIG. 2, the L0 to L3 information recording layers 20, 22, 24, and 26 have spiral grooves 42 (lands) on the surfaces of the substrate 10 and the first to third spacer layers 30, 32, and 34, respectively. 44) is formed. In this case, a recording film is formed on the L0 to L3 information recording layers 20, 22, 24, and 26, and the recording mark 46 can be formed by the energy of the laser beam Z. The groove 42 serves as a guide track for the laser beam Z at the time of data recording. By modulating the energy intensity of the laser beam Z traveling along the groove 42, the information recording layer 20 on the groove 42, Recording marks 46 are formed at 22, 24 and 26. When the data holding mode is a write-once type, the recording mark 46 is irreversibly formed and cannot be erased. On the other hand, when the data holding mode is a rewritable type, the recording mark 46 is formed reversibly and can be erased and re-formed. This recording film also needs to have both light transmittance and light reflection characteristics. Although the case where the recording mark 46 is formed on the groove 42 is shown here, it may be formed on the land 44 or on both the groove 42 and the land 44.

  As described above, when the information recording layers 20, 22, 24, and 26 are formed in multiple layers, in order to make the laser beam Z having sufficient intensity reach the L0 information recording layer 20 farthest from the light incident surface 38A, It is necessary to improve the light transmission characteristics of the information recording layers 22, 24, and 26. According to the study by the present inventors, it is desirable to set the light transmittance of the L3 information recording layer 26 closest to the light incident surface 38A to about 80%.

  Next, the effects of surface defects when recording signals on the multilayer optical recording medium 1 will be described.

  When data is recorded on the multilayer optical recording medium 1 having this structure, the recording laser beam Z incident from the light incident surface 38A is focused on one of the L0 to L3 information recording layers 20, 22, 24, and 26. . For example, as shown in FIG. 3A, when recording is performed on the L3 information recording layer 26, focus control is performed in the L3 information recording layer 26 so that the beam spot S of the laser beam Z3 is substantially minimized. . At this time, an intermediate beam spot S3 larger than the beam spot S is formed on the light incident surface 38A by the laser light Z3. As shown in FIG. 3B, when recording is performed on the L2 information recording layer 24, focus control is performed in the L2 information recording layer 24 so that the beam spot of the laser beam Z2 is substantially minimized. . At this time, an intermediate beam spot S2 larger than the beam spot S is formed on the light incident surface 38A by the laser light Z2. As shown in FIG. 3C, when recording is performed on the L1 information recording layer 22, focus control is performed on the L1 information recording layer 22 so that the beam spot of the laser beam Z1 is substantially minimized. At this time, an intermediate beam spot S1 larger than the beam spot S is formed on the light incident surface 38A by the laser light Z1. As shown in FIG. 3D, when recording is performed on the L0 information recording layer 20, focus control is performed on the L0 information recording layer 20 so that the beam spot of the laser beam Z0 is substantially minimized. At this time, an intermediate beam spot S0 larger than the beam spot S is formed on the light incident surface 38A by the laser light Z0.

  FIG. 4 compares the sizes of the intermediate beam spots S0 to S3 formed on the light incident surface 38A. It can be seen that the intermediate beam spot S3 is the smallest and increases in the order of S2, S1, and S0. This is because the focal point (laser spot S) becomes farther from the light incident surface 38A as the distance from the light incident surface 38A to the information recording layers 20, 22, 24, 26 increases. When the user carries the multilayer optical recording medium 1 or inserts the multilayer optical recording medium 1 into a recording / reproducing apparatus, a foreign substance 50 such as a fingerprint or dust adheres to the light incident surface 38A. The foreign matter 50 deteriorates the recording characteristics of the multilayer optical recording medium 1. In particular, as the ratio of the foreign matter 50 to the intermediate beam spots S0 to S3 formed on the light incident surface 38A increases, the energy of the recording laser beam Z is blocked by the foreign matter 50, so that the formation of recording marks is insufficient. It becomes. Therefore, it can be understood that the L3 information recording layer 26 is easily affected by the foreign matter 50.

  [Reference analysis results]

FIG. 5 shows the results of examining the change in recording characteristics depending on the presence or absence of foreign matters such as fingerprints with respect to the multilayer optical recording medium 1. The multilayer optical recording medium 1 used was the same as in the examples described later. Bit error rate (bER) when reproducing data recorded when there is no surface defect, and bit when reproducing data recorded with an artificially attached fingerprint on the multilayer optical recording medium 1 The error rate (bER) was compared. As a result of this analysis, in the L2 and L3 information recording layers 24 and 26 in which the distance from the light incident surface 38A to the light incident side information recording layer 26 is within 65 μm, the bER is greatly increased due to the influence of fingerprint adhesion. ^-3 . Therefore, it has been clarified that the closer to the light incident surface 38A, the more the surface defects adversely affect the formation of the recording mark.

  Next, an information recording apparatus 100 that realizes the information recording method of the present embodiment will be described with reference to FIG. The information recording apparatus 100 includes a laser light source 102 that generates laser light Z used for recording and reproduction, a laser controller 104 that controls the laser light source 102, an optical mechanism 106 that guides the laser light Z to the multilayer optical recording medium 1, and laser light. Photodetector 108 for detecting the reflected light of Z, multilayer optical recording controller 110 for analyzing detection information of the photodetector 108, spindle motor 112 for rotating the multilayer optical recording medium 1, and spindle motor 112 for rotational control. A signal processing device 116 is provided for exchanging signal data with the spindle driver 114, particularly a CPU (Central Processing Unit) (not shown), and performing recording / reproduction control based on the recording signal data and the reproduction signal data.

  The laser light source 102 is a semiconductor laser and is controlled by the laser controller 104 to generate the laser light Z. The optical mechanism 106 includes a half mirror and an objective lens (not shown), and can appropriately focus the laser beam Z on the L0 to L3 information recording layers 20, 22, 24, and 26. The half mirror takes out the reflected light of the L0 to L3 information recording layers 20, 22, 24, and 26 and guides it to the light detection device. The light detection device 108 is a photo detector, and receives the reflected light of the laser light Z and outputs it as a signal. This signal is provided to the signal processor 116 and output to the CPU as reproduction signal data.

  When the signal data from the CPU is recorded on the multilayer optical recording medium 1, the laser controller 104 controls the laser light source 102 based on an instruction of the signal processing device 116 that has received this signal data, and a predetermined laser beam. Z is generated. The laser beam Z is guided by the optical mechanism 106 and irradiated to any one of the L0 to L3 information recording layers 20, 22, 24, and 26 as a laser spot. Recording marks are formed on the L0 to L3 information recording layers 20, 22, 24, and 26 by the energy of the laser spot.

  On the other hand, in order to reproduce information recorded on the multilayer optical recording medium 1, reproduction laser light is generated from the laser light source 102, and the reproduction laser light is used for the characteristics of the L0 to L3 information recording layers 20, 22, 24 and 26. Irradiate the place. The reproduction laser light is reflected by the L0 to L3 information recording layers 20, 22, 24, and 26, taken out through the optical mechanism 106, guided to the light detection device 108, and becomes a reproduction signal through the signal processing device 116. Provided to the CPU.

  FIG. 7 shows the internal configuration of the multilayer optical recording control device 110. The multilayer optical recording control device 110 includes a defect information collection unit 150, a defect area setting unit 152, an information recording layer selection unit 154, an information write instruction unit 156, an initialization processing unit 158, and the like. When the defect information collecting unit 150 records information by irradiating the L0 information recording layer 20 with the recording laser beam, the defect information collecting unit 150 detects the reflected light of the recording laser beam via the photodetection device 108 and detects the reflected light. The defect information of the multilayer optical recording medium 1 is collected according to the state. Based on this defect information, the surface defect state of the light incident surface 38A is clarified. Further, in the defect information collection unit 150, in order to limit the detection range of the surface defect, a predetermined amount related to the recording work is set in advance, and when the defect information corresponding to the predetermined amount can be collected, the L0 information The recording work for the recording layer 20 is finished, and an instruction is given to shift to the recording work for the other L1-L3 information recording layers 22, 24, and 26. For the determination of the predetermined amount, a certain number of tracks or sectors, information recording amount (number of bits, number of bytes, etc.), recording time, etc. can be used.

  Based on the defect information, the defect area setting unit 152 determines an area where a defect is likely to occur in the recording operation as a defect area, and sequentially stores the defect area and the non-defect area. As a result, the surface defect of the area where information is recorded in the L0 information recording layer 20 is inspected. The information recording layer selection unit 154 selects a suitable information recording layer from the L1 to L3 information recording layers 22, 24, and 26 depending on the defect information or the degree (level) of the defect area set based on the defect information. In this embodiment, the L3 information recording layer 26 is selected when there are few surface defects due to fingerprints, the L2 information recording layer 24 is selected when there are few surface defects, and L1 when there are many surface defects. The information recording layer 22 is selected. As described above, the information recording layers 22, 24, and 26 are selected according to the surface defect level because the closer to the light incident surface 38A, the more easily affected by the surface defect during the recording operation.

  The information writing instruction unit 156 is an information recording layer selected by the information recording layer selection unit 154 (hereinafter referred to as a selected information recording layer), and has been inspected for surface defects through the recording operation of the L0 information recording layer 20. It is instructed to record information while avoiding the recording of the defective area with respect to the area (the area corresponding to the predetermined amount). Specifically, this instruction is given to the signal processing device 116, and the signal processing device 116 that has received these instructions focuses the recording laser beam on the selected information recording layer and outputs information. Record. After the writing of information to the inspected area of the selected information recording layer is completed, the process returns to the L0 information recording layer 20 to start a new recording operation. The initialization processing unit 158 detects the timing at which the multilayer optical recording medium 1 is inserted into the information recording apparatus 100, and initializes the defect area stored in the defect area setting unit 152 each time it is inserted. To do. This is because the multilayer optical recording medium 1 once taken out may have a new fingerprint attached.

  FIG. 8 is a flowchart showing a procedure for recording information using the multilayer optical recording control device 110.

  First, in step 200, the initialization processing unit 158 determines whether or not the multilayer optical recording medium 1 to be recorded has been newly inserted. If the multilayer optical recording medium 1 has been newly inserted, the step is executed. Proceeding to 202, after all the defect information and the like in the previous recording work are initialized (reset), the information recording work (step 204) is started.

  In step 204, information recording work is started using the L0 information recording layer 20. At the same time, in step 206, the defect information collection unit 150 collects defect information (surface defect information) on the light incident surface 38A based on the reflected light from the multilayer optical recording medium 1. At this time, the defect area setting unit 152 determines defect areas using defect information and address information determined to have surface defects, and stores them appropriately in a memory area (not shown).

  In Step 208, it is determined whether or not the amount of defect information collected exceeds a predetermined amount. If the amount does not exceed the predetermined amount, the process returns to Step 204 to continue writing to the L0 information recording layer 20. On the other hand, if it is determined that the collected amount of defect information exceeds the predetermined amount, the process proceeds to step 210 to stop the recording operation on the L0 information recording layer 20. In step 212, the information recording layer selecting unit 154 causes the defect to be recorded. The level of the surface defect is determined based on the area size, and a suitable information recording layer is selected from the L1 to L3 information recording layers 22, 24, and 26. When the surface defect level is high (there are many defects), the L1 information recording layer 22 that is less affected by the surface defect is selected, and when the surface defect level is low (there are few defects), L3 is easily affected by the surface defect. The information recording layer 26 is selected. If the surface defect is at an intermediate level, the L2 information recording layer 24 is selected. Although not specifically shown here, when an information recording layer is selected, the defect area setting unit 152 resets the defect area and the non-defect area based on the permissible level of surface defects of the information recording layer. I have to. When the surface defect level is high at the stage when defect information is collected in this way, it is also preferable to generate an alarm by sound, light, video, etc. to prompt the user to wipe the multilayer optical recording medium 1.

  Next, in step 214, the information writing instruction unit 156 instructs the signal processing device 116 to record information on the inspected area of the selected information recording layer while avoiding the defective area. Upon receiving the instruction, the signal processing device 116 performs the recording operation on the selected information recording layer while avoiding the defective area (step 216), and determines whether the recording operation on the inspected area is completed (step 216). 218) When the recording of the inspected area is completed, the process returns to step 200, and the recording operation in the new area using the L0 information recording layer 20 is started.

  According to the information recording apparatus 100, while recording information on the L0 information recording layer 20, the surface defect of the multilayer optical recording medium 1 is detected by utilizing the reflected light (return light) of the laser light. Therefore, even in the L3 information recording layer 26 that is inferior in fingerprint resistance, it is possible to perform recording while recognizing the state of surface defects in advance, and information recording errors can be reduced. Accurate recording work also leads to improvement of reproduction signal characteristics after recording. Further, since the recording laser beam is effectively utilized while recording information, it is not necessary to separately secure a surface defect inspection time, and the entire recording time can be shortened.

  Further, in this information recording apparatus 100, during the recording operation for the L3 information recording layer 26, the recording operation in the area determined to be a defective area by the defective area setting unit 152 is avoided, so that the recording error can be reduced. Is possible.

  Furthermore, since the L0 information recording layer 20 that is farthest from the light incident surface 38A and has excellent fingerprint resistance is used to simultaneously perform information recording and surface inspection, the recording of the L0 information recording layer 20 is originally performed. In the work, the influence of surface defects can be suppressed. In addition, after this surface inspection, since the recording operation is actively performed on the L3 information recording layer 26 having poor fingerprint resistance, the L0 information recording layer 20 which is resistant to surface defects and the influence of the surface defects. Efficient information recording work can be realized in both the easy L3 information recording layer 26. Further, when there are many surface defects, the L1 or L2 information recording layers 22 and 24 having relatively excellent fingerprint resistance can be selected, so that the recording area of the multilayer optical recording medium 1 can be effectively utilized.

  In the information recording apparatus 100, an upper limit is set for the information recording operation for the L0 information recording layer 20, and when it is determined that the predetermined amount has been reached, the information recording operation for the other information recording layers 22, 24, 26 is performed. It is supposed to be. As a result, it is possible to prevent the L0 information recording layer 20 from being inspected for an unnecessarily large area. For example, this predetermined amount can be set every time based on the total amount of information processed in one recording operation, and is recorded evenly on the L0 to L3 information recording layers 20, 22, 24, and 26. As a result, a quarter of the total information amount may be set as the predetermined amount.

  In the present embodiment, since the area inspected by the recording of the L0 information recording layer 20 and the recording areas in the other information recording layers 22, 24, and 26 overlap in the thickness direction, the reliability of the defect area Can be increased.

  In the above embodiment, the defect information is collected only when the L0 information recording layer 20 is recorded. However, the present invention is not limited to this. For example, after the recording work of the L0 information recording layer 20 is completed, it is possible to collect defect information also during the recording work of the other information recording layers 22, 24, and 26. In this embodiment, information is not recorded on the defect area of the selected information recording layer. However, the present invention is not limited to this, and the defect area has high durability against surface defects. Signals may be recorded intensively, and information in a certain range including defective areas may be recorded by different signal processing methods (particularly a signal processing method having excellent resilience against reproduction errors). May be.

  Further, when information is recorded in the defect area of the selected information recording layer, the effect of surface defects is reduced by increasing the unit recording mark (distance of the medium strip that can be assigned to one bit). Also good. Specifically, as shown in FIG. 2, by increasing the linear density of each recording mark 46, that is, the length T of the unit recording mark 46 in the spiral direction, the recording density is reduced and the durability against surface defects is increased. To increase. The linear density can be controlled by controlling the linear velocity (that is, the rotational speed of the disk) when the laser beam Z travels in the groove. For example, the recording linear velocity is normally set to 4.9 m / s. However, the recording linear velocity is changed to 5.7 m / s for the region where the surface defect exists. In this way, if the rotational speed of the disk is changed, the linear density can be easily changed without changing the recording timing on the laser beam Z side. In addition to changing the linear density, it is possible to substantially reduce the recording density by controlling so that information is not recorded in both the adjacent grooves 43 in the region where the surface defect exists. is there.

  [Example]

  The result of detecting the surface defect state of the multilayer optical recording medium 1 while creating a multilayer optical recording medium and recording information on a predetermined information recording layer using the information recording apparatus 100 according to the present embodiment is as follows. Show.

  [Creation of multilayer optical recording media]

  First, the substrate 10 was manufactured by an injection molding method. A spiral groove having a track pitch of 0.32 μm was formed on the surface of the substrate 10. A polycarbonate resin was used as the material of the substrate 10 and the thickness was set to 1.1 mm and the diameter was 120 mm.

  Next, this substrate 10 was set in a sputtering apparatus, and the L0 information recording layer 20 having a thickness of 48 nm was formed on the surface on the side where the grooves were formed. Specifically, the composition of the L0 information recording layer 20 is bismuth (Bi), oxygen (O), and germanium (Ge), and the composition ratio (atm%) is Bi: O: Ge = 29: 70: 1. Set to.

  Next, the substrate 10 on which the L0 information recording layer 20 was formed was set in a spin coater, and an acrylic ultraviolet curable resin was dropped while being rotated, and this was spin coated. Thereafter, a light transmissive stamper having a spiral groove pattern was pressed against the surface of the spin-coated resin, and the resin was cured by irradiating the resin with ultraviolet rays through the light transmissive stamper. After curing, the light transmissive stamper was peeled off to complete a first spacer layer 30 having a spiral groove (track pitch is 0.32 μm) and a thickness of 17 μm.

  Next, the L1 information recording layer 22 was formed on the first spacer layer 30 by the same method as the L0 information recording layer 20. The composition ratio (atm%) of bismuth (Bi), oxygen (O), and germanium (Ge) was set to Bi: O: Ge = 25: 71: 4, and the thickness was 62 nm.

  Further, a second spacer layer 32 was formed on the L1 information recording layer 22 by the same method as that for the first spacer layer 30. The thickness of the second spacer layer 32 was set to 20 μm. Next, on the second spacer layer 32, the thickness is 68 nm, and the composition ratio (atm%) of bismuth (Bi), oxygen (O), and germanium (Ge) is set to Bi: O: Ge = 25: 68: 7. The L2 information recording layer 24 is formed, and a third spacer layer 34 having a thickness of 13 μm is formed thereon. Further, on the third spacer layer 34, a thickness of 73 nm, bismuth (Bi), oxygen (O ), The L3 information recording layer 26 in which the composition ratio (atm%) of germanium (Ge) was set to Bi: O: Ge = 23: 68: 9 was formed.

  Then, the substrate 10 on which the L3 information recording layer 26 is formed is set in a spin coater, and an acrylic ultraviolet curable resin is dropped while rotating, and the cover layer 36 having a thickness of 48 μm is completed by irradiating it with ultraviolet rays. It was.

  Further, an ultraviolet / electron beam curable hard coating agent is applied onto the cover layer 36 by a spin coating method, and then heated in the atmosphere for 3 minutes to remove the diluting solvent inside the coating, and the uncured hard coating material layer Formed. A surface material solution was applied to the uncured hard coat material layer by a spin coat method. This surface material solution was prepared by adding perfluoropolyether diacrylate (0.33 parts by weight, molecular weight: about 2000) and 3-perfluorooctyl-2-hydroxypropyl to a fluorinated solvent (99.5 parts by weight). It is prepared by adding acrylate (0.17 parts by weight). Thereafter, the hard coat material layer was dried at 60 ° C. for 3 minutes and further irradiated with an electron beam under a nitrogen stream to simultaneously cure the hard coat material layer and the surface material solution, thereby completing the hard coat layer 38. In addition, about the irradiation of an electron beam, the electron beam irradiation apparatus Curetron (made by Nissin High Voltage Co., Ltd.) was used, the electron beam acceleration voltage was 200 kV, and the irradiation dose was 5 Mrad. The oxygen concentration in the irradiation atmosphere was 80 ppm. In this way, a multilayer optical recording medium 1 was obtained.

  [Evaluation of sample recording work]

  An artificial fingerprint was attached to the light incident surface 38A of the multilayer optical recording medium 1. As an artificial fingerprint attachment procedure, first of all, as a material for artificial fingerprints, Kanto loam of test powder 1 type 11 (median diameter: 1.6 to 2.3 μm) defined in JISZ8901 that functions as fine particle powder ( 0.4 parts by weight), triolein (1 part by weight) functioning as a dispersion medium, and methoxypropanol (10 parts by weight) functioning as a diluent were mixed and stirred to obtain an artificial fingerprint liquid. Next, a master plate for pseudo fingerprint pattern transfer was prepared. Specifically, about 1 mL was collected while stirring the artificial fingerprint liquid well with a magnetic stirrer, and this was applied onto a polycarbonate substrate (diameter 120 mm, thickness 1.2 mm) by a spin coat method. This substrate was heated at 60 ° C. for 3 minutes to completely remove the unnecessary diluent, methoxypropanol. In this way, an original plate for transferring a pseudo fingerprint pattern was obtained.

  Furthermore, no. (1) The smaller end surface (diameter: 12 mm) of the silicone rubber plug is uniformly polished with # 240 abrasive paper (having the same performance as JIS stipulated AA240 abrasive paper) to produce a pseudo-fingerprint transfer material (so-called pseudo fingertip) ) Was formed. The artificial fingerprint liquid component is pressed onto the original plate for 10 seconds with a load of 4.9 N for 10 seconds to transfer the artificial fingerprint liquid component to the end surface of the transfer material, and the amount of adhesion of the artificial fingerprint liquid component is reduced in advance. For this purpose, the operation of pressing the end face of the transfer material against the polycarbonate substrate with a load of 4.9 N for 10 seconds was performed three times successively on different portions of the polycarbonate substrate.

  The end surface of the pseudo-fingerprint transfer material prepared in this way is pressed for 10 seconds with a load of 29 N on the light incident surface 38A of the hard coat layer 38 of the multilayer optical recording medium 1 at a position near 40 mm in the radial direction from the center. The artificial fingerprint liquid component was transferred to the light incident surface 38A, thereby forming an artificial fingerprint.

  Using the information recording device 100, the laser beam Z was irradiated to the viewing recording area of the L0 information recording layer 20 in the multilayer optical recording medium 1, and the reflected light was detected by the light detection device 108. FIG. 9A shows a sum signal when the beam spot S is irradiated to the L0 information recording layer 20 located about 100 μm from the light incident surface 38A. As is apparent from the figure, it was found that a region coincident with the fingerprint region can be detected as the defect region EA by using the signal change state. Further, as shown in FIG. 5, in the L0 information recording layer 20, since the bER deterioration due to the adhesion of the fingerprint is small, the recording / reproducing can be surely performed. The reason why the deterioration of bER is small is that, as shown in FIG. 9A, the reflected light changes relatively slowly even in the defect area EA where the fingerprint exists, and the influence of the fingerprint in the information recording work is small. It is thought that it is over. Therefore, it has become clear that the recording operation and the fingerprint detection operation on the light incident surface 38A can be performed simultaneously.

  FIG. 9B shows a sum signal when the beam spot S is irradiated to the L3 information recording layer 26 at a position of about 50 μm from the light incident surface 38A. As is clear from FIG. 9B, it was found that in the region EB coinciding with the fingerprint region, the reflected light changes sharply, so that the influence on the information recording is great. Further, as shown in FIG. 5, in the L3 information recording layer 26, it is actually known that bER is greatly deteriorated by fingerprint adhesion. From the above, the defect area EA is discriminated while recording information using the L0 information recording layer 20, and information is recorded while avoiding the defect area EB in advance in the L3 information recording layer 26 having low fingerprint resistance. It has become clear that the recording error itself can be reduced.

  According to the information recording apparatus 100 of the present embodiment, even if it is a multilayer optical recording medium in which three or more layers, preferably four or more information recording layers are laminated within a very narrow range of about 100 μm from the light incident surface, Information can be efficiently recorded while avoiding surface defects. In this embodiment, the information recording layer of the multilayer optical recording medium is shown as being only four layers. However, the present invention is not limited to this, and may be two layers, three layers, or five layers or more. Also good.

  Furthermore, in the present embodiment, the first information recording layer is shown only when the L0 information recording layer 20 farthest from the light incident surface 38A is used. However, the present invention is not limited thereto, and other information recording layers are used. May be used. For example, when information has already been recorded in a predetermined area of the information recording layer farthest from the light incident surface, the next information recording layer farthest is appropriately selected to perform recording and detection of surface defects. May be.

  The information recording apparatus of the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the gist of the present invention.

  According to the present invention, it is possible to record information reliably and efficiently by effectively utilizing the characteristics of the multilayer optical recording medium.

A perspective view and an enlarged sectional view showing a multilayer optical recording medium used in an embodiment of the present invention. An enlarged perspective view showing a data holding form in the information recording layer of the multilayer optical recording medium Sectional drawing which shows the state which records the information of each information recording layer of the multilayer optical recording medium An enlarged plan view schematically showing a beam spot formed on the light incident surface of the multilayer optical recording medium and an attached fingerprint. Chart showing the results of analyzing the relationship between the position of the information recording layer of the optical recording medium and the anti-fingerprint property during recording The block diagram which shows the structure of the information recording device which concerns on embodiment of this invention The block diagram which shows the structure of the multilayer optical recording control apparatus integrated in the information recording device Flow chart showing an information recording procedure in the information recording apparatus Analysis diagram showing a state where a fingerprint on the light incident surface is detected in the embodiment Sectional view schematically showing the structure of a conventional DVD Sectional view schematically showing the structure of a conventional hybrid DVD Chart showing the effect of fingerprints on optical recording media

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Multi-layer optical recording medium 10 ... Substrate 20 ... L0 information recording layer 22 ... L1 information recording layer 24 ... L2 information recording layer 26 ... L3 information recording layer 30 ... First DESCRIPTION OF SYMBOLS 1 Spacer layer 32 ... 2nd spacer layer 34 ... 3rd spacer layer 36 ... Cover layer 38 ... Hard coat layer 38A ... Light incident surface 100 ... Information recording apparatus 102 ... Laser light source 104 ・ ・ ・ Laser controller 106 ・ ・ ・ Optical mechanism 108 ・ ・ ・ Photodetection device 110 ・ ・ ・ Multi-layer optical recording control device 112 ・ ・ ・ Spindle motor 114 ・ ・ ・ Spindle driver 116 ・ ・ ・ Signal processing device 150 ... Defect information collection unit 152 ... Defect region setting unit 154 ... Information recording layer selection unit 156 ... Information write instruction unit 58 ... initialization processing unit

Claims (13)

An information recording method for recording information on a multilayer optical recording medium having a plurality of information recording layers,
The first information recording layer whose distance from the light incident surface is set to be larger than 65 μm is irradiated with recording laser light to record information, and reflected light of the recording laser light is detected to detect the multilayer optical recording medium. Collect defect information,
Regardless of whether or not the first information recording layer becomes a defect area, the defect area of the second information recording layer whose distance from the light incident surface is set to 65 μm or less according to the level of the defect information, and Non-defective areas are determined in advance,
An information recording method for a multilayer optical recording medium, wherein information is recorded by irradiating a recording laser beam to the second information recording layer while avoiding the defective area.   2. The information recording method for a multilayer optical recording medium according to claim 1, wherein the first information recording layer is set to have a distance from the light incident surface within 100 [mu] m. 3. The information recording method for a multilayer optical recording medium according to claim 1 or 2 , wherein an information recording layer that is farthest from the light incident surface of the multilayer optical recording medium is selected as the first information recording layer. . The information of the multilayer optical recording medium according to any one of claims 1 to 3 , wherein the information recording layer having the shortest distance from the light incident surface of the multilayer optical recording medium is selected as the second information recording layer. Recording method. 5. The information on the multilayer optical recording medium according to claim 1 , wherein a suitable second information recording layer is selected from a plurality of information recording layers using the level of the defect information. Recording method. 6. The information recording method for a multilayer optical recording medium according to claim 1 , wherein when it is determined that the multilayer optical recording medium has been taken out to the outside, the defect information is initialized. The multilayer according to any one of claims 1 to 6 , wherein when it is determined that the amount of information recorded on the first information recording layer has reached a predetermined amount, the information recording action on the second information recording layer is performed. Information recording method for optical recording medium. 8. The information recording method for a multilayer optical recording medium according to claim 7 , wherein a recording area or an information recording amount is preset as the predetermined amount. 9. The information recording method for a multilayer optical recording medium according to claim 7 , wherein an information recording time is preset as the predetermined amount. With respect to the said recording laser beam by the information recording area for the first information recording layer, any one of claims 1 to 9, characterized in that overlap the second information recording layer of the information recording area in the thickness direction An information recording method of the multilayer optical recording medium described. 11. The information recording method for a multilayer optical recording medium according to claim 1, wherein the first information recording layer is a rewritable type in which recorded information can be erased and recorded again. A control apparatus for multilayer optical recording used in an information recording apparatus for recording information on a multilayer optical recording medium having a plurality of information recording layers,
The reflected light of the recording laser beam is detected when information is recorded by irradiating the recording laser beam on the first information recording layer whose distance from the light incident surface is set to be larger than 65 μm. A defect information collection unit for collecting defect information;
Regardless of whether or not the first information recording layer is a defect area, the distance from the light incident surface is set to 65 μm or less according to the level of the defect information in the defect information collection unit. A defect area setting unit for setting a defect area and a non-defect area of the recording layer;
An information writing instruction unit for instructing recording of information on the second information recording layer while avoiding the defective area;
A control device for multilayer optical recording, comprising: The multilayer optical recording control device according to claim 12, a laser light source that generates the recording laser light, a laser controller that controls the laser light source, an optical mechanism that guides the recording laser light to the multilayer optical recording medium, An information recording apparatus for a multilayer optical recording medium, comprising: a light detection device that detects reflected light of the recording laser light and provides information to the control device.

Images