JP2008152879A - Optical disk drive and control method of the optical disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To position an objective lens to an optimum position at the recording and reproducing operation by easily adjusting the position of objective lens. <P>SOLUTION: By reproducing data recorded on a DVD-RAM having a header field and shifting the objective lens by an actuator, reading rates of the header fields at a plurality of positions are acquired (steps S11-S19), and a position where the reading rate becomes highest is computed and stored (steps S20-S21) from the relation between the position of objective lens and the reading rate. When the optical disk drive is used, the objective lens is positioned and operated, based on the positional information stored that is the highest in the reading rate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical disc apparatus having an objective lens and a method for controlling the optical disc apparatus.

  Optical discs are used to record content such as images, music, and videos, and to record data used by computers. The optical disc apparatus reads data recorded on the optical disc by irradiating the optical disc with laser light from the pickup head and receiving reflected light from the optical disc.

  Reflected light from the optical disk is received by the photodetector, but if the balance of the light incident on the photodetector is deviated from the center, the reproduction capability is reduced and an error occurs.

As a conventional technique, there is a technique in which a tangential phase difference is intentionally shifted, a shift amount of the objective lens is detected and corrected by the phase difference offset, and then tracking error balance adjustment is performed (for example, see Patent Document 1). ).
JP 2000-315327 A

  In the invention described in Patent Document 1, the configuration of the apparatus becomes complicated, for example, a mechanism for intentionally shifting the tangential phase difference is required to obtain the optimum position. Therefore, a method that can easily adjust the position of the objective lens is desired.

  An object of the present invention is to provide an optical disc apparatus capable of easily adjusting the position of an objective lens and optimizing the reproduction capability, and a method for controlling the optical disc apparatus.

  In order to achieve the above object, an optical disc apparatus according to the present invention is an optical disc apparatus for reproducing an optical disc having a plurality of recording areas including a header portion and a data area in which data is recorded. On the other hand, a pickup head having a laser beam irradiating unit that irradiates laser beam through the objective lens, a photodetector that receives reflected light from the optical disc through the objective lens, and the objective lens on the optical disc. An actuator for driving in a perpendicular direction and a radial direction with respect to a track; a reproduction circuit for reproducing data recorded in the optical data based on an output signal of the photodetector; and controlling the actuator to control the objective lens While moving to a plurality of different positions, The reading rate of the header portion is calculated based on the reproduction data of, and the position where the reading rate is highest is calculated from the relationship between the plurality of different positions of the objective lens and the reading rate corresponding thereto, And a controller for storing the position in a memory so as to be usable.

  An optical disk apparatus control method is an optical disk apparatus control method for reproducing an optical disk having a plurality of recording areas including a header portion and a data area in which data is recorded. Reproduction data obtained from the detection signal of the reflected light from the optical disk at each of the moved positions by controlling the actuator for driving in the vertical direction and the radial direction to move the objective lens to a plurality of different positions. And calculating the position where the reading rate is highest from the relationship between the plurality of different positions of the objective lens and the corresponding reading rate, and using the position. It is possible to store it in a memory.

  According to the optical disk device of the present invention, the position of the objective lens can be easily adjusted, and the objective lens during recording and reproduction can be positioned at an optimum position.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of the optical disc apparatus according to the embodiment.

  The optical disk 61 is rotationally driven by a spindle motor 63. Information recording and reproduction with respect to the optical disc 61 is performed by an optical pickup head 65 (a portion surrounded by a broken line in the drawing). The optical pickup head 65 is connected to a thread motor 66 through a gear, and the thread motor 66 is controlled by a thread motor control circuit 68.

  A speed detection circuit 69 located in the lower part of the sled motor 66 in the figure detects the moving speed of the optical pickup head 65 and is connected to a sled motor control circuit 68. Then, the speed signal of the optical pickup head 65 detected by the speed detection circuit 69 is sent to the sled motor control circuit 68. In addition, a permanent magnet (not shown) is provided at the fixed portion of the thread motor 66, and the optical pickup head 65 is driven in the radial direction of the optical disk 61 by exciting the drive coil 67 by the thread motor control circuit 68. The

  The optical pickup head 65 is provided with an objective lens 70 supported by a wire or a leaf spring (not shown). The objective lens 70 can be moved in the tracking direction (the direction orthogonal to the optical axis of the lens) and the focusing direction (the optical axis direction of the lens) by driving the drive coils 71 and 72.

  When recording data on the optical disc 61, the modulation circuit 73 receives data to be recorded from the host device 94 via the interface circuit 93 and the bus 89, and transmits this data to a modulation method (for example, 8 -16 modulation). The laser drive circuit 75 supplies a write signal to the semiconductor laser diode 79 based on the modulation data supplied from the modulation circuit 73. The laser drive circuit 75 supplies a read signal smaller than the write signal to the semiconductor laser diode 79 during information reproduction.

  The semiconductor laser diode 79 generates laser light toward the optical disc 61 in accordance with a signal supplied from the laser drive circuit 75. Laser light emitted from the semiconductor laser diode 79 is irradiated onto the optical disc 61 through the collimator lens 80, the half prism 81, and the objective lens 70. The reflected light from the optical disc 61 is guided to the photodetector 84 (photo detector) through the objective lens 70, the half prism 81, the condenser lens 82, and the cylindrical lens 83. Of the components constituting the optical system, the objective lens is designed so that the laser beam can be properly focused on the disk.

  The photodetector 84 is composed of, for example, four-divided photodetector cells 84a to 84d. An output signal of each of the light detection cells 84a to 84d of the light detector 84 is added by an adder 86a that adds the outputs of the light detection cell 84a and the light detection cell 84c through current / voltage conversion amplifiers 85a to 85d, respectively. An adder 86b for adding the outputs of the photodetection cell 84b and the photodetection cell 84d, an adder 86c for adding the outputs of the photodetection cell 84a and the photodetection cell 84c, and adding the outputs of the photodetection cell 84b and the photodetection cell 84d. It is supplied to the adder 86d. The outputs of the adders 86a and 86b are supplied to the differential amplifier OP2, and the outputs of the adders 86c and 86d are supplied to the differential amplifier OP1.

  The differential amplifier OP2 generates a focus error signal FE according to the difference between both output signals of the adders 86a and 86b. The focus error signal FE is supplied to the focusing control circuit 87. The output signal FC of the focusing control circuit 87 is supplied to the focusing drive coil 72. The focusing drive coil 72 drives the objective lens 70 based on the output signal FC supplied from the focusing control circuit 87 so that the laser light is always just focused on the recording surface of the optical disc 61. Further, the focusing control circuit 87 has a measurement function for measuring the amplitude of the focus error signal FE, and the measurement value is output to the CPU 90 via the bus 89.

  The differential amplifier OP1 generates a tracking error signal TE corresponding to the difference between both output signals of the adders 86c and 86d. The tracking error signal TE is supplied to the tracking control circuit 88, and the tracking control circuit 88 generates a tracking drive signal according to the tracking error signal TE. The tracking drive signal output from the tracking control circuit 88 is supplied to a tracking drive coil 71 that drives the objective lens 70 in a direction orthogonal to the optical axis. Based on the tracking drive signal, the tracking drive coil 71 drives the objective lens 70 so that the laser beam is applied to a predetermined location on the recording surface of the optical disc 61. The tracking error signal TE is also supplied to the sled motor control circuit 68 via the tracking control circuit 88.

  By performing the focusing control and the tracking control as described above, the adder 86e that adds the sum signal of the output signals of the photodetection cells 84a to 84d of the photodetector 84, that is, the output signals of the adders 86c and 86d, is added. A signal faithful to the recorded information can be obtained by the output sum signal RF. The output sum signal RF is supplied to the data reproduction circuit 78.

  Next, the data reproduction circuit 78 reproduces the read recording data based on the reproduction clock signal from the PLL circuit 76.

  The sled motor control circuit 68 controls the sled motor 66 and moves the main body of the optical pickup 65 so that the objective lens 70 is positioned near the center position in the optical pickup 65.

  The motor control circuit 64, thread motor control circuit 68, modulation circuit 73, laser drive circuit 75, PLL circuit 76, data reproduction circuit 78, focusing control circuit 87, tracking control circuit 88, etc. are configured in one LSI chip. These circuits are controlled by the CPU 90 via the bus 89. The CPU 90 comprehensively controls the optical disc recording / reproducing device in accordance with an operation command supplied from the host device 94 via the interface circuit 93. Further, the CPU 90 uses the RAM 91 as a work area and performs predetermined control according to a program including processing according to the present embodiment recorded in the nonvolatile memory (NVM) 92.

  The optical disc 61 is configured by coating a metal film layer such as tellurium or bismuth in a donut shape on the surface of a substrate formed in a circle with glass or plastics, for example. Then, data is recorded using both concentric or spiral grooves and lands, or recorded data is reproduced, and address data is recorded at predetermined intervals by recording marks in the mastering process. It is a rewritable disc.

  As shown in FIG. 2, the optical disc 61 is divided into a plurality of zones 61A, 61B, 61C,. The clock signals for the zones 61A, 61B, 61C, ..., 61S are the same. The rotation speed (speed) of the optical disc 61 with respect to each of the zones 61A, 61B, 61C,..., 61S is different (becomes slower from the inner circumference toward the outer circumference). The number of sectors per track is different for each zone 61A, 61B, 61C,..., 61S.

Each zone 61A, 61B, 61C of the optical disk 61, ..., the track of the 61S, the header portion 61 _1, each address and the like are recorded, ... are previously pre-formatted for each sector.

As shown in FIG. 3, the header portion 61 ₁ is composed of a plurality of pits 101, and is preformatted with respect to the groove 102 as shown in the figure, and the center of the pit 101 is the groove 102 and the land 103. It exists at the same tangent line.

  As shown in FIG. 3, pit row ID1 is the header portion of groove 1, pit row ID2 is the header portion of land 1, pit row ID3 is the header portion of groove 2, pit row ID4 is the header portion of land 2, and pit row ID5. Is the header portion of the groove 3 and the pit row ID 6 is the header portion of the land 3. Therefore, the headers for grooves and the headers for lands are formed alternately (staggered).

FIG. 4 shows an example of a format for each sector of each zone 1a of the optical disc 61. 4, one sector is formed of, for example, 2697 bytes (bytes), (corresponding to the header portion 1 ₁₎ 128-byte header area 100, is composed of a mirror mark region 110,2564 byte of the recording area 120 of 5 bytes ing. The recording area 120 includes, for example, a cap area 121 of 17 to 19 bytes, a VF03 area 122 of 50 bytes, a data area 123 of 2418 bytes, a card data area 124 of 30 bytes, and a buffer area 125 of 47 to 49 bytes. ing.

  The channel bits recorded in the sector are in the form of 8-16 code modulation of 8 bits of data into 16 bits of channel bits. The header area 100 is an area where predetermined data is recorded when the optical disc 61 is manufactured. The header area 100 is composed of four address areas PID1 to PID4.

  Here, the address areas PID1 and PID3 are composed of 46 bytes, and the breakdown is a 36-byte synchronization code portion VFO1 (Variable Frequency Oscillator), a 3-byte address mark AM (Address Mark), a 4-byte address portion PID (Position). Identifier) is composed of a 2-byte error detection code IED (ID Error Detection Code) and a 1-byte postamble PA (Postambles).

  On the other hand, the address areas PID2 and PDI4 are composed of 18 bytes, and the breakdown is an 8-byte synchronization code portion VFO2 (Variable Frequency Oscillator), a 3-byte address mark AM (Address Mark), a 4-byte address portion PID (Position Identifier). ) It is composed of a 2-byte error detection code IED (ID Error Detection Code) and a 1-byte postamble PA (Postambles).

  The synchronization code parts VFO1 and VFO2 are areas for pulling in the PLL. The synchronization code portion VFO1 is a continuous bit pattern of “010...” Recorded by channel bits for 36 bytes (a pattern at a constant interval is recorded), and the synchronization code portion VFO2 is a continuous pattern of channel bits “010. Is recorded for 8 bytes.

  The address mark AM is a “3” byte synchronization code indicating where the sector address starts. As a pattern of each byte of the address mark AM, a special pattern that does not appear in the data portion “0100100000000100” is used.

The address areas PID1 to PID4 are areas where sector addresses (including ID numbers) as 4-byte address information are recorded. ID number, for example, in the case of PID1 is "1", a number indicating the ordinal number of inner being overwritten four times with one of the header portion 1 _1.

  The error detection code IED is an error (error) detection code for a sector address (including an ID number), and can detect the presence or absence of an error in the read PID.

Postamble PA includes a state information necessary for demodulation and has a role of poling as the header portion 1 ₁ is completed by a space.

  Next, the 5-byte mirror mark area 110 is used for offset correction of a tracking error signal, generation of timing of a land / groove switching signal, and the like.

  Next, the gap area 121 of the recording area 120 is an area where nothing is written.

  The VFO3 area 122 is also an area for PLL locking, but it is also an area intended to synchronize byte boundaries by inserting a synchronization code into the same pattern.

  The data area 123 is an area composed of a synchronization code, ECC (Error Collection Code), EDC (Error Detection Code), user data, and the like.

  The guard data area 124 is an area provided in order to prevent the terminal degradation at the time of repeated recording unique to the phase change recording medium from reaching the data area.

Buffer area 125, as the data area does not overlap the next header portion 1 _1, which is an area provided for absorbing and rotation fluctuation of the motor for rotating the optical disk 61.

  The reason why the gap area 121 is expressed as 17 to 19 bytes is that random shift is performed. Random shift is to shift the data writing start position to alleviate repeated recording deterioration of the phase change recording medium. The length of the random shift is adjusted by the length of the buffer area 125 located at the end of the data area, and the length of one sector is 2697 bytes (fixed).

  Next, a method for adjusting the objective lens 70 in a direction substantially perpendicular to the track provided on the optical disc 61 will be described. Adjustment of the objective lens 70 is performed at the factory. After the above-described optical disk (for example, DVD-RAM) is loaded in the optical disk apparatus, the interface circuit 93 receives a test signal from the host apparatus 94, whereby the following processing is executed.

  FIG. 5 is a flowchart showing a procedure of optimum position detection processing of the objective lens 70 of the optical disc apparatus according to the embodiment of the present invention.

  The CPU 90 calculates the header reading rate at the current position P (0) of the optical pickup head 65 (step S11). Explaining the method of calculating the header reading rate, the CPU 90 determines the address areas PID1 to PID4 of the header area 100 and the error detection code IED from the reproduced data from the data reproducing circuit 78. Then, the CPU 90 calculates the reading rate of the header area by comparing the reading results of the address areas PID1 to PID4 and the corresponding error detection codes IED1 to IED4.

  Next, the CPU 90 instructs the tracking control circuit 88 to move the optical pickup head 65 from P (0) to the inner circumference side, for example, to a position P (-50) separated by 50 μm (step S12). When the optical pickup head 65 moves, the CPU 90 receives the reproduction data RF from the data reproduction circuit 78, and calculates the header reading rate at the current position P (-50) of the optical pickup head 65 (step S13).

  Next, the CPU 90 instructs the tracking control circuit 88 to move the optical pickup head 65 from P (0) to the inner peripheral side, for example, to a position P (-100) separated by 100 μm (step S14). When the optical pickup head 65 moves, the CPU 90 receives the reproduction data RF from the data reproduction circuit 78, and calculates the header reading rate at the current position P (-100) of the optical pickup head 65 (step S15).

  Similarly, the CPU 90 instructs the tracking control circuit 88 to move the optical pickup head (PUH) 65 from P (0) to the outer peripheral side, for example, to a position P (+50) separated by 50 μm (step S16). . When the optical pickup head 65 moves, the CPU 90 receives the reproduction data RF from the data reproduction circuit 78, and calculates the header reading rate at the current position P (+50) of the optical pickup head 65 (step S17).

  Further, the CPU 90 instructs the tracking control circuit 88 to move the optical pickup head 65 from P (0) to the outer peripheral side, for example, to a position P (+100) of 100 μm (step S18). When the optical pickup head 65 moves, the CPU 90 receives the reproduction data RF from the data reproduction circuit 78, and calculates the header reading rate at the current position P (+100) of the optical pickup head 65 (step S19).

Based on the relationship between the position of the optical pickup head 65 obtained in this way and the header reading rate, the CPU 90 calculates with an approximate expression of a quadratic function (y = ax ² + bx + c, see FIG. 6) (step S20). . Here, y is an axis of the header reading rate, and x is an axis of the position of the optical pickup head 65.

  Then, the CPU 90 calculates a maximum point from the obtained quadratic function curve, and calculates the position of the optical pickup head 65 at which the header reading rate is maximized (step S21). The first derivative of the quadratic function is y ′ = 2ax + b. Therefore, when y ′ = 0, x is −b / 2a, and the position of the objective lens 70 taking the maximum point is −b / 2a.

  As described with reference to FIG. 3, the optical disk 61 has groove header portions and land header portions formed alternately (staggered). Therefore, when the position of the objective lens 70 is the center of the land or groove, the reading rate of the header is the highest. Therefore, the header reading rate of the objective lens 70 is obtained at a plurality of positions, and the position of the objective lens 70 and the header reading rate are approximated by a quadratic function, so that the header reading rate becomes the highest from the approximated quadratic function. Can be predicted.

  Finally, the CPU 90 stores the calculated position information in the nonvolatile memory (NVM) 92 (step S92).

  In this way, the optical disk apparatus can be shipped with the optimum position of the objective lens 70 stored. Then, when the optical disk apparatus is powered on after shipment, the CPU 90 supplies an offset voltage to the tracking control circuit 88 based on the information on the optimum position stored in the nonvolatile memory (NVM) 92. Thereby, the position of the objective lens 70 can be positioned at a position set before shipment. As a result, unexpectedly, the head position at the time of recording and reproduction of an optical disk such as DVD, DVD ± R, DVD ± RW, etc. can be positioned at an optimum position.

  As described above, with respect to the DVD-RAM, the objective lens 70 is set at a plurality of positions, the header reading rate at each position is measured, and the position where the header reading rate is expected to be maximum is obtained. Thus, the optimum position of the objective lens 70 can be easily obtained.

  Although the adjustment of the objective lens 70 is performed before shipment from the factory, it may be appropriately performed when the user loads the DVD-RAM into the optical disc apparatus after shipment from the factory.

Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

1 is a block diagram showing a schematic configuration of an optical disc apparatus according to an embodiment of the present invention. The figure for demonstrating the example of a format of an optical disk. The figure for demonstrating the preformat data of a header part. The figure which shows the sector format of an optical disk. The flowchart which shows the procedure of the process of the optimal position detection method of the objective lens concerning one Embodiment of this invention. The figure which shows the relationship between the position of an objective lens, and a header reading rate.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 61 ... Optical disk, 63 ... Spindle motor, 65 ... Optical pick-up, 68 ... Thread motor control circuit, 69 ... Speed detection circuit, 70 ... Objective lens, 71 ... Drive coil, 78 ... Data reproduction circuit, 79 ... Semiconductor laser diode, 84 ... Photodetector, 88... Tracking control circuit, 89... Bus, 90.

Claims (6)

An optical disc apparatus for reproducing an optical disc having a plurality of recording areas each including a header portion and a data area in which data is recorded,
A pickup head having an objective lens, a laser light irradiation unit that irradiates the optical disc with laser light via the objective lens, and a photodetector that receives reflected light from the optical disc via the objective lens;
An actuator for driving the objective lens in a vertical direction and a radial direction with respect to the optical disc;
A reproducing circuit for reproducing the data recorded in the optical data based on an output signal of the photodetector;
While controlling the actuator to move the objective lens to a plurality of different positions, the read rate of the header portion is calculated based on reproduction data from the reproduction circuit for each position, and the plurality of objective lenses And a controller that calculates the position where the reading rate is highest from the relationship between the different positions and the corresponding reading rate, and stores the position in a memory so as to be usable. In the header portion of the optical disc, an error detection code is set for each of a plurality of address areas,
2. The optical disk apparatus according to claim 1, wherein the controller calculates the reading rate by comparing the reading result of the error detection code with the address area.   The optical disk apparatus according to claim 1, wherein the controller positions the objective lens from position information stored in the memory at power-on.   The controller calculates a quadratic function curve that approximates the relationship between the plurality of different positions of the objective lens and the reading rate corresponding thereto, and the reading rate is a maximum value of the calculated quadratic function curve. 2. The optical disk apparatus according to claim 1, wherein the optical disk apparatus is obtained as the highest position. A method for controlling an optical disc apparatus for reproducing an optical disc having a plurality of recording areas each including a header portion and a data area in which data is recorded,
Controlling an actuator for driving the objective lens in a direction perpendicular to the track on the optical disc and in a radial direction to move the objective lens to a plurality of different positions;
Calculate the reading rate of the header portion based on the reproduction data obtained from the detection signal of the reflected light from the optical disc for each moved position,
From the relationship between the plurality of different positions of the objective lens and the corresponding reading rate, the position where the reading rate is highest is calculated,
A method for controlling an optical disc apparatus, wherein the position is stored in a memory so as to be usable.   A quadratic function curve that approximates the relationship between the plurality of different positions of the objective lens and the corresponding reading rate is calculated, and the maximum value of the calculated quadratic function curve is set as the position where the reading rate is the highest. 6. The method for controlling an optical disk apparatus according to claim 5, wherein the method is obtained.

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