JP2010231840A - Optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk device having the improved efficiency of interlayer jumping, for solving the problem wherein an interlayer jumping in a disk having three or more recording layers, the amplitude of a focus error signal drops on a more separated recording layer, due to the influence of spherical aberrations and a focal position needs to be moved, taking into account the influence of spherical aberrations, when performing interlayer jumping. <P>SOLUTION: When interlayer jumping is performed in the disk having three or more recording layers, based on a relation between the recording layer, before the movement of a focus and the recording layer after the movement, an objective lens and a spherical aberration correction mechanism are driven in different sequences. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an optical disc apparatus. In particular, for example, the present invention relates to an optical disc apparatus that performs data recording or reproduction on an optical disc having a plurality of recording layers.

  In Patent Document 1, for example, in the summary column, “When performing a focus jump, the objective lens 11 is accelerated by the acceleration pulse generated by the jump pulse generation circuit 10, and then the zero cross detection circuit 8 zeroes the focus error signal. When the period near the level is detected, the acceleration is stopped and the objective lens 11 is driven at a constant speed. ”“ When performing a focus jump in an optical disc having a plurality of recording layers, one recording layer and the other The instability of the focus jump due to the noise generated between the recording layers and the variation in the sensitivity of the actuator is eliminated.

  In Patent Document 2, for example, in the summary column, “At the time of focus jump, the focus error signal at the end of the deceleration pulse is measured, and the output timing of the deceleration pulse of the next focus jump is corrected based on this value. There is a description that "the operation shifts to the optimum focus jump pulse by continuing."

JP-A-9-50630 JP 11-345420 A

  Currently, in a standardized digital versatile disc (hereinafter referred to as DVD), a single-sided dual-layer disc has a recording layer on each of two 0.6 mm discs, and has a high reflectivity of aluminum. A plurality of recording layers can be accessed from one side by laminating a disk with a film and a disk with a semitransparent gold reflective film.

  For a dual-layer disc, each objective lens is moved and focused on each recording layer based on the focus error signal at a point where the objective lens is in focus (hereinafter referred to as in-focus). Access to the recording layer and reading of recorded information can be performed. This focal point movement between layers (hereinafter referred to as interlayer jump) has been described in, for example, Patent Document 1 and Patent Document 2. .

  A focus error signal is used for the interlayer jump described in Patent Document 1 and Patent Document 2. In this case, it is assumed that the signal amplitude of the focus error signal is greater than or equal to an arbitrary threshold value in the vicinity of the current recording layer and in the vicinity of the recording layer to be moved.

  However, when considering a disc having three or more recording layers, the physical distance of each recording layer from the disc surface is different. When the focal point of the laser beam is positioned with respect to each recording layer, spherical aberration is generated according to the thickness of the cover layer from the surface to the recording surface, and thus the amount of spherical aberration generated varies from recording layer to recording layer. Since the amount of reflected light decreases due to spherical aberration, the amplitude of the focus error signal generated from the reflected light also decreases.

  Further, in a Blu-ray Disc (hereinafter referred to as BD), a laser spot size is reduced by using a lens having a high numerical aperture, and the recording density is about five times that of a DVD. Since the spherical aberration at the focal point is proportional to the fourth power of the numerical aperture, the influence of the spherical aberration is larger on the BD than on the DVD. In BD, since the influence of spherical aberration due to a high numerical aperture is large, an element for correcting spherical aberration is provided.

  As described above, in an interlayer jump in a disc having three or more recording layers, the amplitude of the focus error signal in a farther recording layer is reduced due to the influence of spherical aberration. Therefore, when performing an interlayer jump to a distant recording layer, it is necessary to move the focal position while taking into account the influence of spherical aberration.

  An object of the present invention is to provide an optical disc apparatus that improves the efficiency of interlayer jumps.

  The above problems are solved by, for example, the invention described in the claims. The main points are briefly described as follows.

  When performing an inter-layer jump in a disc having three or more recording layers, the objective lens and the spherical aberration correction mechanism are driven in a different order depending on the relationship between the recording layer before the focus movement and the recording layer after the movement.

  According to the present invention, it is possible to provide an optical disc apparatus that improves the efficiency of interlayer jump.

Schematic diagram showing the configuration of an optical disk device Schematic illustrating the focus error signal of a multi-layer disc Schematic illustrating the total light quantity signal of a multi-layer disc Schematic illustrating the interlayer jump by the first control means Schematic illustrating the interlayer jump by the second control means Schematic diagram showing the configuration of an optical disk device Schematic diagram showing a disk structure example of a multilayer disk

  Hereinafter, embodiments of the optical disk device will be described.

  First, the configuration of the optical disc apparatus will be described with reference to the schematic diagram of FIG.

  In FIG. 1, reference numeral 101 denotes an optical disc having N recording layers (N is an integer of 3 or more) accessible from one side. Reference numeral 102 denotes an objective lens for condensing the laser light on the recording layer of the disk. Reference numeral 103 denotes a driving unit for driving the objective lens 102. Reference numeral 104 denotes a light receiver that receives laser light reflected from the optical disk. Reference numeral 105 denotes error signal generation means for generating a focus error signal indicating the deviation between the focal point on the disk and the recording layer from the laser light received by the light receiver 104. Reference numeral 106 denotes drive signal generation means for generating a drive signal for driving the drive means 102. Reference numeral 107 denotes drive voltage supply means for supplying a drive voltage to the drive means 103 in accordance with the drive signal. Reference numeral 108 denotes a laser light emitting unit. Reference numeral 109 denotes an aberration correction mechanism for correcting the focal aberration on the disk. Reference numeral 110 denotes an aberration correction control unit that operates the aberration correction mechanism 109 to perform aberration correction. Reference numeral 111 denotes first control means for performing an interlayer jump by driving the objective lens moving means 103 and the aberration correction mechanism 109 in a predetermined order by the drive signal generating means 106 and the aberration correction control means 110. Reference numeral 112 denotes second control means for driving the objective lens moving means 103 and the aberration correction mechanism 109 in an order different from that of the first control means 111 to perform interlayer jump. Reference numeral 113 denotes the first control unit 111 or the second control unit 112 according to the recording layer information in which the focus is currently positioned according to the necessity of the interlayer jump and the target recording layer information in which the focus is positioned by the interlayer jump. Is a selection means for performing the interlayer jump.

  In FIG. 1, the optical head 114 is composed of 102 to 104, 107, and 108.

  In the apparatus of FIG. 1, the objective lens 102 condenses the laser light emitted from the laser light emitting unit 108 on the optical disc 101 to generate a focal point.

The spherical aberration correction mechanism 109 is used to correct spherical aberration at the laser focus on the disk. Further, the spherical aberration correction mechanism 109 is disposed in the optical path of the laser between the laser light emitting unit 108 and the objective lens 102. The configuration is such that the lens is driven along the optical axis of the laser. It may correct light aberration.
Hereinafter, the configuration of the spherical aberration correction mechanism 109 will be exemplified as a configuration for driving an aberration correction lens disposed in the laser optical path.
In addition, setting the spherical aberration correction mechanism 109 to an optimal or suitable state for recording or reproduction in an arbitrary Xth recording layer (X is an integer of 1 or more and N or less) indicates that “the Xth recording layer (the first recording layer The spherical aberration correction mechanism 109 is set in the “X layer”. When the position of the aberration correction lens is represented by z, the aberration correction lens position when the spherical aberration correction mechanism 109 is set in the Xth layer is z _x . It is assumed that z _{1 to} z _N are also in order when the recording layers are arranged in numerical order from the first layer to the Nth layer. The aberration correction lens position z may be controlled with a finer precision than the lens position with respect to each recording layer, and may be set to an intermediate point of the recording layer such as z = (z ₁ + z ₂ ) / 2.

  In addition, any one or more of the first control unit 111, the second control unit 112, and the selection unit 113 may be implemented by a single control circuit such as an MPU. The single control circuit may include any one or more of the error signal generation unit 105, the drive signal generation unit 106, and the aberration correction control unit 110.

  Here, the position control in the case where the focus is positioned on one recording layer will be described with an example. When the laser beam reflected from the optical disc 101 is received by the light receiver 104, the error signal generation means 105 generates a focus error signal from the received laser beam. The drive signal generation unit 106 generates a drive signal in accordance with the focus error signal, and the drive voltage supply unit 107 supplies a voltage to the moving unit 103 in accordance with the drive signal to move the position of the objective lens 102 to change the focus position. to correct. In this way, the position of the focal point and the recording layer is fed back to the position of the lens so that the focal position is precisely controlled by focus servo.

  The optical disc apparatus of the present embodiment has N (N ≧ 3) recording layers, and the Mth (M ≦ N, M is the Mth) with respect to the optical disc 101 in which the first to Nth recording layers are arranged in numerical order. From the state where the focal point is controlled to a positive integer recording layer (hereinafter referred to as the Mth layer), the Lth (L ≦ N, L is a positive integer, M ≠ L) recording layer (hereinafter referred to as the first layer). When performing an interlayer jump in which the focal point is moved between recording layers until the focal point is controlled in the L layer), the selection unit 113 switches the interlayer jump operation.

  The selection unit 113 calculates a difference D = | M−L | between the current recording layer number M and the recording layer number L targeted for focal movement. When D is less than a predetermined value A (A is a positive number), the selection unit 113 performs an interlayer jump by the first control unit 111. When D is equal to or greater than the predetermined number A, the selection unit 113 performs an interlayer jump by the second control unit 112.

  Here, a case where the focus is moved from the first recording layer to another recording layer (in the case of M = 1) with respect to the optical disk having four recording layers (N = 4) will be described as a specific example. .

  When the focal point is moved from the first recording layer to the second recording layer (L = 2), the selection unit 113 selects the interlayer jump operation by the recording layer number D = | 1-2 | = 1. In this embodiment, if A = 1.5 as an example, an interlayer jump is performed by the first control unit 111 when D = 1.

  Next, an example of an interlayer jump by the first control unit 111 will be described with reference to FIG. The first control unit 111 observes the level of the focus error signal when performing the interlayer jump. In FIG. 2, when moving the focus position from the first layer to the second layer, the first control unit 111 observes the focus error signal while moving the objective lens, and whether or not the focus has reached the second layer. Is detected. Specifically, it is detected whether or not the focus error signal satisfies the following three conditions.

1) the focus error signal falls below _{V 2.}

2) the focus error signal exceeds the _{V 1.}

3) After observing the signal change in 1) and 2) above, the focus error signal became near the signal center V ₀ .

Accordingly, the first control unit 111 stops the movement of the objective lens 102 when the 3) focus error signal is in the vicinity of V ₀ and starts feedback control on the second layer. Thereafter, the first control unit 111 sets the spherical aberration correction mechanism 109 to a spherical aberration setting at which recording or reproduction is optimal or suitable on the second layer, and the interlayer movement to the second layer is completed. The timing of changing the focus error signal, the position of the objective lens 102, and the setting position of the spherical aberration correction mechanism 109 at this time is as shown in FIG.

  As in the above example, the first control unit 111 moves the focus from the Mth layer to the Lth layer by moving the objective lens 102 once, and corrects spherical aberration before and after the movement of the objective lens 102. The setting of the mechanism 109 is changed.

  Next, the operation when the focus moves from the first recording layer (hereinafter referred to as the first layer, also referred to as the second layer to the fourth layer) to the fourth recording layer (L = 4) will be described. . The selection unit 113 selects an interlayer jump operation based on the recording layer number difference D = | 1−4 | = 3. As described above, in this embodiment, when A = 1.5, interlayer jump is performed by the second control unit 112 when D = 3.

  An example of the interlayer jump by the second control means 112 will be described with reference to FIG.

When performing the interlayer jump, the second control unit 112 observes the level of the focus error signal in the same manner as the first control unit 111 described above. In FIG. 2, before moving from the first layer to the fourth layer, the spherical aberration correction mechanism 109 is set in the first layer as shown in FIG. Here, if only the objective lens 102 is driven without correcting the spherical aberration and the focal position is moved to the fourth layer side, the amplitudes of the focus error signals corresponding to the third layer and the fourth layer are as follows. less than the detection level _{V 1} and _{V 2} of the recording layer. Therefore, the positions of the third layer and the fourth layer are not detected. Therefore, the second control unit 112 changes the setting of the spherical aberration correction mechanism 109 before the objective lens 102 is moved. At this time, setting of the spherical aberration correcting mechanism 109, (1) the amplitude of the focus error signal corresponding to the first layer does not fall below the V ₁ and V _2, (2) fourth layer side as viewed from the first layer Is performed so that the signal amplitude of the focus error signal for the other recording layers existing in is higher than V ₁ and V ₂ for more recording layers. In FIG. 2, the two conditions are satisfied when the setting of the spherical aberration correction mechanism 109 is set to the second layer as shown in FIG. In this case, the second control unit 112 sets the spherical aberration correction mechanism 109 at this position. Thereby, the amplitude of the focus error signal in the first layer can be maintained at a predetermined level or more, so that the focus servo control for the first layer can be continued.

Next, the objective lens 102 is moved by the driving means 103. According to FIG. 2 (b), the case of driving the objective lens 102 in the direction of the fourth layer from the first layer, a focus error signal corresponding to the first to third layers exceeds the threshold value V ₁ and V ₂ Yes. Therefore, the positions of the first layer to the third layer can be detected. Accordingly, it is possible to move the objective lens 102 while fixing the setting of the spherical aberration correction mechanism 109 to move the focus position from the first layer to the third layer, and to position it on the third layer. The second control unit 112 positions the focus on the third layer and starts focus servo control on the third layer.

In a state where focus servo control is performed on the third layer, the spherical aberration correction mechanism 109 is further moved to the fourth layer side, and the spherical aberration correction mechanism is set so that recording or reproduction is suitable on the fourth layer. When the spherical aberration correction mechanism 109 is set as described above, a focus error signal shown in FIG. 2D is obtained. Here, when moving the objective lens 102 to the fourth layer side, the focus error signal corresponding to the third layer and the fourth layer is above the threshold value V ₁ and V _2, since it is possible to detect the two recording layer position, The focal position can be moved to the fourth layer. The timing of changing the focus error signal, the position of the objective lens 102, and the setting position of the spherical aberration correction mechanism 109 at this time is as shown in FIG.

In this way, the second control unit 112 drives the spherical aberration correction mechanism 109 and the objective lens 102 alternately to position the focal point on the target recording layer. The spherical aberration correction mechanism 109 is driven by: (1) the amplitude of the focus error signal corresponding to the recording layer on which the focal point is located does not fall below a predetermined level; and (2) the target Lth layer within the range satisfying (1). The spherical aberration correction mechanism 109 is set so as to satisfy the two conditions of being the position closest to the set value z _L of the spherical aberration correction mechanism 109. The objective lens 102 is driven by positioning the recording layer closest to the target L-th layer as viewed from the M-th layer among the recording layers in which the amplitude of the focus error signal is greater than a predetermined value. The above movement is repeated until the focal position reaches the Lth layer.

The conditions for setting the position of the aberration correction mechanism 109 are (1) the amplitude of the focus error signal corresponding to the recording layer on which the focal point is positioned does not fall below a predetermined value, and the range that satisfies (2) (1). The target position is the position closest to the setting value z _L of the spherical aberration correction mechanism 109 of the Lth layer, and (3) the setting values z _{1 to} z _N of any one of the recording layers. One may be a condition.

In the above example, the spherical aberration correction mechanism 109 is driven at the beginning of the movement, but the objective lens 102 may be driven first to reverse the order of driving. Further, the value of A is not limited to the value of this embodiment. And the amount of spherical aberration caused when moving the objective lens 102, determined by such as the value of the threshold V ₁ and V ₂ of the recording layer detection when jump.

In the example of FIG. 2, the focus error signal decreases when the objective lens is moved from the first layer to the second layer side, and the focus error signal increases when the objective lens moves in the opposite direction to the second layer. However, the polarity of the focus error signal may have the opposite polarity to the example of FIG. In this case, V ₁ and V ₂ are set below and above the level V ₀ of the focus error signal when the focus is on the recording layer, respectively.

  In this embodiment, the focus error signal is used for detecting the position of the recording layer. However, the total light amount signal (also referred to as a pull-in error signal) of reflected light may be used, and the present invention is not limited to this. FIG. 3 exemplifies a total light amount signal observed in the vicinity of each recording layer when the objective lens 102 is moved by changing the setting of the spherical aberration correction mechanism 109 for a disk having four recording layers. It is. Similar to the example of FIG. 2, the spherical aberration increases and the total light amount signal decreases as the focal point moves away from the recording layer in which the spherical aberration correction mechanism 109 is set.

  In this embodiment, the selection unit 113 selects the control method based on the recording layer number M of the recording layer where the focal point is currently positioned and the recording layer number L as the movement target. However, the index used by the selection unit 113 is as follows. It is not limited to this.

For example, when the distances from the surfaces of the N recording layers are d ₁ to d _N (d _{1 to} d _N are positive numbers), the selection unit 113 has the Mth focal point positioned before the movement. The distance d _ML = | d _M −d _L | between the layer and the Lth layer as the movement target is acquired. The selecting means 113, if d _ML is less than the predetermined value B (B is a positive number), select the first control means 111, when d _ML is more than the predetermined value B, the second control It may be configured that the means 112 is selected and the interlayer jump is performed by the selected control means.

Further, when the spherical aberration correction mechanism 109 is configured to move the spherical aberration correction lens arranged in the laser optical path along the optical axis of the laser, the selection unit 113 may perform the following processing. Good. For example, when the lens position of the spherical aberration correcting spherical aberration in each of the N recording layers is optimal for recording or reproducing _(the z ₁ to z _N positive numbers) z ₁ to z N and selecting means 113 Is the position z _M of the spherical aberration correcting lens corresponding to the Mth layer, the focal point of which is positioned before the interlayer jump, and the position z _L of the spherical aberration correcting lens corresponding to the Lth layer to be moved. Difference z _ML = | z _M −z _L |. When the selection means 113 z _ML is (are C positive number) predetermined value C of less than, select the first control means 111, if z _ML is higher than the predetermined value C, the second control means 112 is selected, and a process of performing an interlayer jump is performed by the selected control means.

In the first control unit, the order in which the spherical aberration correction mechanism 109 is set to the Lth layer is not limited to after the objective lens 102 is moved. For example, as shown in FIG. 2B, even when the spherical aberration correction mechanism 109 is set to the Lth layer (L = 2 in the above example), the Mth layer (M = 1 in the above example) is used. as long as the amplitude of the focus error signal exceeds the V _1, it may change the setting of the spherical aberration correcting mechanism 109 prior to driving of the objective lens 102. Further, the spherical aberration correction mechanism 109 is set to a substantially intermediate position between the Mth layer and the Lth layer before the objective lens 102 is driven, and the spherical aberration correction mechanism 109 is moved after the focal point is moved to the Lth layer by the objective lens 102. May be set in the Lth layer.

  Moreover, the process of a 2nd control means is not limited to the process mentioned above. The processing of the second control means is to perform a spherical aberration correction mechanism before the focal point of the laser beam reaches a position where the focus error signal cannot obtain a sufficient amplitude if the setting of the spherical aberration correction mechanism 109 is not changed. Any configuration may be used as long as the change of the setting 109 is started. A configuration in which the setting of the spherical aberration correction mechanism 109 is changed during the movement of the focal position may be employed.

  In the present embodiment, an optical disk having four recording layers is taken as an example. However, the present invention is applicable to an optical disk having three or more recording layers, and the number of recording layers is not limited to this. .

  As described above, in this optical disc apparatus, the interlayer jump is performed by the control by the first control means or the control by the second control means. The second control means changes the setting of the spherical aberration correction mechanism 109 at least before the focus error signal does not reach the threshold value. For this reason, even if the layers before and after the movement are separated from the predetermined value, it becomes possible to accurately reach the target layer. On the other hand, the first control means can position the focal point without changing the setting of the spherical aberration correction mechanism 109. That is, according to the first control means, the timing for driving the objective lens 102 to the target layer is not limited by the operation of the spherical aberration correction mechanism 109. For this reason, in the first control means, it is possible to suppress a decrease in speed at which the objective lens 102 is driven to the target layer. This optical disc device enables high-speed interlayer jumps for layers closer to the threshold, and executes interlayer jumps for layers farther than the threshold while maintaining focus control stability. It becomes possible to do.

  Example 2 will be described below.

  The optical disc apparatus of this embodiment is characterized in that, for example, a threshold value for selecting a method for performing an interlayer jump is obtained by learning.

  Next, the configuration of the optical disc apparatus will be described with reference to the schematic diagram of FIG.

  In FIG. 6, the constituent elements 101 to 114 are the same as those in the first embodiment, and a description thereof will be omitted. Reference numeral 115 denotes reproduction means for reproducing information on the disk from the reflected light. Reference numeral 116 denotes recording means for recording information by modulating laser light. Reference numeral 117 denotes a learning unit that learns the threshold value in the interlayer jump from the error signal generated by the error signal generation unit 105 or the information reproduced by the reproduction unit 115. Reference numeral 118 denotes a storage unit that stores a learning result obtained by the learning unit 117.

  The reproduction unit 115 and the recording unit 116 are configured by a dedicated signal processing circuit such as a DSP, for example.

  In the present embodiment, the learning unit 117 learns a threshold for the selection unit 113 to select either the first control unit 111 or the second control unit 112. The learning unit 117 is configured by controlling the MPU, for example. Further, a dedicated signal processing circuit such as a DSP may be used. Further, the learning unit 117 may be mounted by being incorporated in the same control circuit as the first control unit 111 and the second control unit 112. In this specification, the term “learning means” is used for ease of explanation, but any acquisition means for acquiring a threshold value may be used.

  The storage unit 118 is constituted by a semiconductor memory, for example.

  Next, the threshold learning method by the learning unit 117 will be described with an example. When learning is performed, the spherical aberration correction mechanism 109 is set to the first layer. Next, the learning unit 117 maintains the setting of the spherical aberration correction mechanism 109 and the objective lens 102 from the front of the disk 101 toward the back as viewed from the objective lens 102 so that the focal point passes through the N recording layers. Drive. The learning unit 117 determines the threshold value in relation to the number of recording layers detected at this time.

Here, a specific example of the learning method will be described by taking an optical disc having four recording layers as an example. In a four-layer optical disk, a waveform as shown in FIG. 2A for the focus error signal and a waveform as shown in FIG. 3A for the total light amount signal are obtained. When the focus error signal is used as an index for detecting the recording layer, as shown in FIG. 2A, the focus error signal becomes the operating point center V ₀ after exceeding the threshold value V ₁ , and if the threshold value V ₂ is subsequently exceeded, the recording layer is detected. Can be detected. In the case of FIG. 2A, the number of recording layers detected is two.

  Further, the threshold value used by the selection unit 113 is determined in relation to the control procedure of the first control unit 111 and the second control unit 112. For example, when the first control unit 111 performs an interlayer jump in the same control procedure as the control method illustrated in the first embodiment, the objective is set before changing the setting of the spherical aberration correction mechanism 109 as shown in FIG. The lens 102 is driven to change the focal position to another recording layer. In this case, the threshold value A is set to a number greater than 1 and equal to or less than 2 as the number of detected recording layers as the learning result. Thereby, the first control unit 111 is used when the recording layer to be moved can be detected without driving the spherical aberration correction mechanism 109, and the second control unit 112 is used in other cases to move the focal point. Is divided into a plurality of times, so that stable interlayer jumps are possible.

  The aforementioned learning method is an example and is not limited to this. For example, a total light amount signal may be used as an index for detecting the recording layer.

  In the embodiment, learning is performed by setting the spherical aberration correction mechanism 109 in the first layer that is present in the forefront among the N recording layers, but the spherical aberration correction mechanism is set in another recording layer that is not located at the end. 109 may be set for learning. However, in this case, since the recording layer on the near side and the recording layer on the back side are detected with respect to the recording layer for which the spherical aberration correction mechanism 109 is set, the threshold value is set on both recording layers with respect to the detected number of recording layers. It is necessary to consider the value. For example, as shown in FIG. 2B, when the spherical aberration correction mechanism 109 is set to the second layer and learning is performed, the number of detections of the recording layer becomes 3, but in the procedure of the interlayer jump by the first control unit 111 described above, Since the procedure is to drive the objective lens 102 from the current recording layer first, one recording layer on one side can be seen at the time of interlayer jump, and the threshold A is set to a number greater than 1 and less than or equal to 2 To do.

  Note that the number of detected recording layers and the learning result vary depending on the interlayer jump method by the first control unit 111, and are not limited to this. For example, when the spherical aberration correction mechanism 109 is set approximately halfway between the Mth layer and the Lth layer before the objective lens 102 is driven as a control procedure of the first control unit 111, the threshold value of the selection unit 113 is set. Learning is performed by setting the spherical aberration correction mechanism 109 to the recording layer that is not the end as shown in FIG. 2B, and the detected recording layer 3 is a number that is greater than 1 and less than or equal to 3 as the threshold A. May be set.

  The storage unit 118 stores the learning result obtained by the learning unit 117. In addition, the storage unit 118 may store unique information for identifying the optical disc 101 such as the disc ID and medium type together with the learning result. When the ID of the disc is recognized, the previous learning result is read from the storage means 118, so that the threshold value can be determined without performing the learning operation.

  Further, the learning result may be recorded on the optical disc 101 by the recording means 116. Here, the storage area on the optical disc 101 of the learning result will be exemplified using the schematic diagram showing the disc structure example of FIG. FIG. 7 is a diagram showing the configuration of the disc area in an optical disc having four recording layers. A description of the components having the same reference numerals as those in FIG. 2 is omitted. In FIG. 7, each recording layer has a management area on the inner circumference side of the disc, a user data area, and a management area on the outer circumference side. The optical disc apparatus records the learning result in one of the management areas in FIG. For example, the optical disc apparatus may be configured to record the learning result in the management area of the extreme recording layer. As a result, the learning result can be reproduced before performing the interlayer jump.

  Further, the learning unit 118 may acquire the learning result by reproducing the learning result information recorded on the optical disc 101, and thereby the threshold for the selection unit 113 to select the control unit may be determined. Thus, learning can be performed in a shorter time than determining the threshold value from the number of recording layers detected by the learning operation described above.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  In addition, each of the above-described configurations may be configured such that some or all of them are configured by hardware, or are implemented by executing a program by a processor. Further, the control lines and information lines indicate what is considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

101 optical disc,
102 objective lens,
103 moving means,
104 photodetectors,
105 error signal generating means,
106 drive signal generating means,
107 driving voltage supply means;
108 Laser emission part,
109 spherical aberration correction mechanism,
110 Aberration correction control means,
111 first control means,
112 second control means,
113 selection means,
114 optical head,
115 reproducing means,
116 recording means,
117 learning means,
118 storage means,
202 first recording layer,
203 second recording layer,
204 the third recording layer,
205 Fourth recording layer.

Claims (10)

An optical disc apparatus for recording or reproducing information on a disc having recording layers from the first layer to the Nth layer (N is an integer of 3 or more),
Lens driving means for driving the objective lens in the direction of the focal depth of the laser focus;
Spherical aberration correcting means for correcting the spherical aberration of the laser beam;
First control means for moving the laser focus between different recording layers of the disk by driving the lens driving means and the spherical aberration correction means in a first order;
Second control means for moving the laser focus between different recording layers by driving the lens driving means and the spherical aberration correcting means in a second order different from the first order;
When the laser focus moves from the Mth (1 ≦ M ≦ N, M is an integer) recording layer to the Lth (1 ≦ L ≦ N, L is an integer, L ≠ M) recording layer, the Mth Selecting means for selecting the first or second control means according to the position of the recording layer and the position of the L-th recording layer;
An optical disc apparatus comprising: The optical disc apparatus according to claim 1,
Said selection means, the physical distance D ₁ of the M-th recording layer and the L-th recording layer _{(D 1} is a positive number) when a predetermined value d _{1 (d 1} is the number of positive) less than A first control means is selected for the optical disk apparatus, and if the D ₁ is greater than or equal to d _1, the second control means is selected. The optical disc apparatus according to claim 1,
When the difference K (K = | M−L |) between the Mth recording layer and the Lth recording layer number is smaller than a predetermined value k ₁ (k ₁ is a positive integer), the selection means selecting one of the control means, in the case of the K is k ₁ or the optical disk apparatus characterized by selecting the second control means. The optical disc apparatus according to claim 1,
The spherical aberration correction means corrects the amount of spherical aberration by driving a spherical aberration correction lens arranged in the optical path of the laser light irradiated to the optical disc in the optical axis direction.
The selection means is configured to record or record when the focal point is positioned on the Lth recording layer and the position of the spherical aberration correcting lens where the spherical aberration is optimal for recording or reproduction when the focal point is positioned on the Mth recording layer. When the positional difference D ₂ (D ₂ is a positive number) with respect to the position of the spherical aberration correcting lens at which the spherical aberration is optimal for reproduction is smaller than a predetermined amount d ₂ (d ₂ is a positive number). selecting one of the control means, when said D ₂ is equal to or greater than the predetermined amount d ₂ is an optical disk apparatus characterized by selecting the second control means. The optical disc apparatus according to claim 1,
A focus error signal indicating a position error of the laser focus with respect to the recording surface on the optical disc is generated as a focus error signal generation means, and the selection means determines whether the focus control signal is a first control means or a second control means. An acquisition means for acquiring a threshold value for selection,
The acquisition unit acquires a threshold value based on the focus error signal measured when the laser focus passes through the N recording layers by driving the objective lens in the focal direction, and the selection unit sets the acquired threshold value to the acquired threshold value. An optical disc apparatus characterized by switching a control method in focus movement between recording layers accordingly. The optical disc apparatus according to claim 1,
Total light amount signal generating means for generating a total light amount signal indicating the amount of reflection of the laser light from the optical disc;
An acquisition means for acquiring a threshold when the selection means selects either the first control means or the second control means based on the total light amount signal;
The acquisition unit acquires a threshold value based on the total light amount signal measured when the laser focus passes through the N recording layers by driving the objective lens in the focal direction, and the selection unit sets the acquired threshold value to the acquired threshold value. An optical disc apparatus characterized by switching a control method in focus movement between recording layers accordingly. The optical disc apparatus according to claim 1,
A focus error signal generating means for generating a focus error signal indicating a positional deviation of the laser focus;
An acquisition means for acquiring a threshold value when the selection means selects either the first control means or the second control means by the focus error signal;
Recording means for recording information on the optical disc,
The acquisition unit acquires a threshold value based on the focus error signal measured when the laser focus passes through the N recording layers by driving the objective lens in the focal direction, and the recording unit sets the threshold value on the optical disc. An optical disc apparatus for recording on the optical disc apparatus. The optical disc apparatus according to claim 1,
Total light amount signal generating means for generating a total light amount signal indicating the amount of reflection of the laser beam with respect to the recording surface on the optical disc;
An acquisition means for acquiring a threshold when the selection means selects either the first control means or the second control means based on the total light amount signal; a recording means for recording information on the optical disc; With
The acquisition means acquires the threshold value based on the total light amount signal measured when the laser focus passes through the N recording layers by driving the objective lens in the focal direction,
The optical disk apparatus, wherein the recording means records the acquired threshold value on the optical disk. An optical disc apparatus for recording or reproducing information on a disc having recording layers from the first layer to the Nth layer (N is an integer of 3 or more),
Lens driving means for driving the objective lens in the direction of the focal depth of the laser focus;
Spherical aberration correcting means for correcting the spherical aberration of the laser beam;
A first process of moving the laser focus between different recording layers of the disk by driving the lens driving means and the spherical aberration correcting means in a first order; and the lens driving means and the spherical aberration correcting means; Control means for performing any one of the second process of moving the laser focus between different recording layers by driving in a second order different from the first order,
The control means moves the laser focus from the Mth (1 ≦ M ≦ N, M is an integer) recording layer to the Lth (1 ≦ L ≦ N, L is an integer, L ≠ M) recording layer. An optical disc apparatus that controls to perform either the first process or the second process according to the position of the Mth recording layer and the position of the Lth recording layer. An optical disc apparatus for recording or reproducing information on a disc having recording layers from the first layer to the Nth layer (N is an integer of 3 or more),
Lens driving means for driving the objective lens in the direction of the focal depth of the laser focus;
Spherical aberration correcting means for correcting the spherical aberration of the laser beam;
Control means for driving the lens driving means and the spherical aberration correcting means in a specific order to move the laser focus between different recording layers of the disk,
The control means sets the laser focal point of the disk in which the recording layers are arranged in order from the first to the Nth to a laser focus L that is two or more away from the Mth from the Mth (1 ≦ M ≦ N, M is an integer) recording layer. (1 ≦ L ≦ N, L is an integer, L ≠ M, | LM− ≧ 2), the objective moves from the Mth recording layer toward the Lth recording layer. An optical disc apparatus characterized in that a focal point is moved between recording layers by alternately driving a lens and the spherical collection difference correcting means.

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