JP4144558B2 - Optical disk device - Google Patents

Description

  The present invention relates to an optical disc apparatus for reproducing data recorded on an optical disc having one or two recording layers.

2. Description of the Related Art Conventionally, an optical disk device that records video and audio on an optical disk such as a DVD or a CD has been widely used. An optical disc apparatus irradiates a recording layer of an optical disc, which is a recording medium, with a laser beam via an objective lens, and reads data recorded on the optical disc and records data on the optical disc. As is well known, the optical disk apparatus is equipped with a focus servo control for aligning the focus position of the laser beam irradiated on the optical disk with the recording layer of the optical disk at the time of data reading and recording, and the laser beam irradiated on the optical disk. Tracking servo control is performed to align the irradiation position with the center in the track width direction. The focus servo control is a direction in which the objective lens is brought into contact with or separated from the optical disk based on a focus error signal (hereinafter referred to as an FE signal) corresponding to a deviation amount between the recording layer of the optical disk and the focus position of the laser beam. It is control to move to. The tracking servo control is based on a tracking error signal (hereinafter referred to as a TE signal) corresponding to the amount of deviation between the center in the width direction of the track formed on the optical disc and the focus position of the laser beam. In this control, the lens or the pickup head body is moved in the radial direction of the optical disk.

  In order to increase the recording density, a DVD in which two recording layers are formed, a so-called two-layer disc, has been proposed. In recent optical disc apparatuses, reading of data recorded on a two-layer disc and two layers are proposed. A function for recording data on a disc is provided. The control for reading data from the optical disk and recording data on the optical disk is basically the same even if the recording layer has two layers. Data is read or recorded by focus servo control and tracking servo control. The laser beam is irradiated to the track of the recording layer that is the target of the recording.

However, as disclosed in Patent Document 1, since the reflectance of the recording layer differs between the single-layer disc and the double-layer disc, it depends on the type of optical disc to be handled (single-layer disc or double-layer disc). If the amplification factor of the optical signal based on the reflected light from the detected optical disk is not adjusted, focus servo control and tracking servo control cannot be performed properly, and as a result, data cannot be read or recorded properly. For this reason, the optical disc apparatus 1 determines whether the optical disc set in the main body (the optical disc to be handled) is a single-layer disc or a double-layer disc, and determines the amplification factor for the optical signal according to the determination result. is doing. In Patent Document 1, one layer is provided if there is one S-shaped signal included in the FE signal detected while moving the objective lens in the direction of contact with and away from the optical disk when the optical disk is set in the main body. The disc is determined to be a disc, and if there are two discs, it is determined to be a dual-layer disc.
Japanese Patent Laid-Open No. 10-188457

  However, in the optical disc determination method disclosed in Patent Document 1, the FE signal detected while moving the objective lens in the direction of moving toward and away from the optical disc is affected by the surface shake caused by the warp of the optical disc. It was a signal. For this reason, depending on the degree of surface deflection of the optical disk, even if the optical disk actually set is a single-layer disk, it may be erroneously determined that there are two S-shaped signals in the detected focus error signal. When such a misjudgment is made, the adjustment of the amplification factor of the optical signal is not properly performed, so that the focus servo control and tracking servo control, and further, the data reading and recording cannot be performed properly. Invited, there is a problem that the reliability of the apparatus main body is lowered.

  The object of the present invention is to accurately determine whether the recording layer of the optical disc set in the main body is one layer or two layers without being affected by the surface deflection caused by warpage of the optical disc set in the main body. An object of the present invention is to provide an optical disc apparatus that can make a good determination and does not reduce the reliability of the apparatus main body.

  The optical disc apparatus of the present invention has the following configuration in order to solve the above problems.

(1) Rotating an optical disc with one or two recording layers set in the main body, irradiating this optical disc with a laser beam through an objective lens, and detecting the reflected light, recording on this optical disc Reading means for reading the stored data;
A lens moving means for moving the objective lens in a direction of moving toward and away from the optical disc;
At the time of reading data by the reading means, the lens moving means performs the lens moving means based on a focus error signal corresponding to the amount of deviation between the recording layer of the optical disc and the focus position of the laser light applied to the optical disc. In an optical disc apparatus provided with focus control means for controlling the movement of the objective lens and adjusting the in-focus position to the recording layer of the optical disc,
When an optical disk is set on the main body, a change in the focus error signal with respect to the rotational position of the optical disk set on the main body is acquired as a surface shake measurement signal in a state where the movement of the objective lens by the lens moving means is prohibited. 1 acquisition means;
While the optical disk is rotated, the objective lens is moved toward and away from the optical disk by the lens moving means . The focus error signal for the rotational position of the optical disk obtained at this time is Second acquisition means for acquiring a signal obtained by subtracting the surface shake measurement signal at the corresponding rotational position as a recording layer number determination signal;
Or recording layer of the optical disc set on the main body on the basis of the recording layer number determination signal the second acquisition means has acquired is one layer, Bei determining means for determining a two-layer, the strong point Yes.

In this configuration, when the optical disk is set in the main body by the first acquisition means, the focus error signal for the rotational position of the optical disk set in the main body is prohibited in a state where the movement of the objective lens by the lens moving means is prohibited. The change is acquired as a runout measurement signal. The surface shake measurement signal acquired by the first acquisition unit indicates a change in the distance between the objective lens and the recording layer of the optical disc during one rotation of the optical disc. On the other hand, since the objective lens is prohibited from moving and is fixed, the change in the distance is a signal indicating surface deflection due to warping of the optical disk or the like. In other words, it is possible to acquire the degree of surface shake of the optical disc set in the main body from the surface shake measurement signal acquired by the first acquisition unit.

Further, with the second acquisition means rotating the optical disk, the lens moving means moves the objective lens in the direction of contacting and separating from the optical disk, and the focus on the rotation position of the optical disk obtained at this time is obtained. A signal obtained by subtracting the surface shake measurement signal at the corresponding rotational position of the optical disc from the error signal is acquired as a recording layer number determination signal. As a result, a recording layer number determination signal from which the influence of surface deflection due to warpage of the optical disk or the like is eliminated can be obtained. Then, the determination unit determines whether the recording layer of the optical disc is one layer or two layers based on the recording layer number determination signal from which the influence of the surface shake due to the warp or the like of the optical disc is removed.

  As described above, when determining whether the recording layer of the optical disk is one layer or two layers, the recording layer number determination signal from which the influence of the surface shake due to the warp of the optical disk is removed is used. Whether the recording layer is one layer or two layers can be accurately determined, and the reliability of the apparatus main body is not lowered.

  Note that the acquisition of the surface shake measurement signal and the recording layer number determination signal by the first acquisition unit and the second acquisition unit is preferably performed on the same track of the optical disc, and the track on the outer peripheral side where the surface shake appears greatly. Is preferable.

  (2) The first acquisition means estimates a change in the focus error signal during one rotation of the optical disk from a focus error signal measured at a plurality of rotational positions of the optical disk, and uses this to calculate the surface shake measurement signal. And

  In this configuration, a focus error signal is measured at four points of 0 degrees, 90 degrees, 180 degrees, and 270 degrees with respect to a plurality of rotational positions, for example, a position where the rotational angle of the optical disk is at a certain position, and the focus error signals at these four points are measured. From this change, a change in the focus error signal during one rotation of the optical disk is estimated, and this is used as a surface shake measurement signal. As described above, since the configuration is obtained by measuring the focus error signal at a plurality of rotational positions, the processing time required for detecting the surface shake measurement signal can be shortened, and as a result, the recording layer of the optical disk can be reduced. It is possible to shorten the time required for determining whether the number of layers is one or two.

  According to the present invention, when determining whether the recording layer of the optical disc is one layer or two layers, it is not affected by the surface shake due to the warp or the like of the optical disc. Or the two layers can be accurately determined, and the reliability of the apparatus main body is not lowered.

  Hereinafter, an optical disk apparatus according to an embodiment of the present invention will be described.

  FIG. 1 is a diagram showing a configuration of a main part of an optical disc apparatus according to an embodiment of the present invention. An optical disc apparatus 1 according to this embodiment includes a control unit 2 that controls the operation of the main body, a pickup head 3 that irradiates a laser beam onto an optical disc 10 that is set in the apparatus main body, records data, and reads data. The servo control unit 4 that adjusts the irradiation position of the laser beam emitted from the head 3 and the recording data to be recorded on the optical disc 10 are encoded, and the laser beam emitted from the pickup head 3 to the optical disc 10 is controlled based on the encoded data. A recording unit 5 that decodes a read signal read from the optical disc 10 by the pickup head 3 and outputs the read signal as a reproduction signal, and a spindle motor 7 that rotates the optical disc 10.

  The pickup head 3 is attached to a shaft extending in the radial direction of the optical disk 10 set in the main body, and a feed mechanism unit (not shown) provided in the servo control unit 4 drives the thread motor 4a to pick up the pickup head. 3 is moved in the radial direction of the optical disk 10 along this axis. The pickup head 3 is provided with an objective lens. This objective lens is attached to a biaxial actuator (not shown) for moving in a direction in which the objective lens is in contact with or separated from the optical disk 10 and in a radial direction of the optical disk 10. Although not shown, the pickup head 3 includes a light emitting element for irradiating the optical disk 10 with laser light and a light receiving element for receiving reflected light from the optical disk 10. Further, the servo mechanism unit 4 moves the objective lens provided in the pickup head 3 in the direction of contacting and separating from the optical disk 10 based on a known focus error signal (hereinafter referred to as FE signal). A focus servo control unit (not shown) for performing focus servo control for adjusting the focus position of the laser light emitted from the light emitting element of the pickup head 3 to the recording layer of the optical disc 10, and a known tracking error signal (hereinafter referred to as TE). A tracking servo mechanism unit that performs tracking control for moving the objective lens in the radial direction of the optical disk 10 and irradiating the target track with laser light emitted from the light emitting element of the pickup head 3 (referred to as a signal). (Not shown) is provided. The movable amount of the lens by the focus servo mechanism unit and the tracking servo mechanism unit is several hundred μm. The feed mechanism moves the pickup head 3 in the radial direction of the optical disc when the target track cannot be irradiated with the laser light emitted from the light emitting element of the pickup head 3 only by moving the lens by the tracking servo mechanism. Tracking control is performed by combining the movement of the pickup head 3 by the feeding mechanism and the movement of the lens by the tracking servo mechanism.

  The recording unit 5 encodes the input recording data, turns on / off the laser light applied to the optical disc 10 from the light emitting element provided in the pickup head 3 based on the encoded data, and stores the encoded recording data. Recording on the optical disk 10. The reproducing unit 6 decodes the read signal that is the output of the light receiving element of the pickup head 3 that has received the reflected light from the optical disc 10, and outputs this as a reproduced signal. The spindle motor 7 is rotated by a drive unit (not shown) to rotate the optical disc 10 set in the main body.

  Here, an optical disc having one recording layer and an optical disc having two layers will be briefly described. As is well known, in the case of the optical disk 10 having a single recording layer, when the objective lens of the pickup head 3 is moved in the direction in which it is in contact with or separated from the optical disk 10, the FE signal shown in FIG. It is done. In FIG. 2A, the horizontal axis is the distance between the objective lens and the optical disc 10, and the vertical axis is the magnitude of the FE signal. A point A shown in FIG. 2A is a point where the recording layer of the optical disc 10 and the focus position of the laser light irradiated from the pickup head 3 are in alignment. Further, in the case of the optical disk 10 having two recording layers, when the objective lens of the pickup head 3 is moved in a direction in which it is in contact with or separated from the optical disk 10, an FE signal shown in FIG. In FIG. 2B, the horizontal axis is the distance between the objective lens and the optical disc 10 as in FIG. 2A, and the vertical axis is the magnitude of the FE signal. Point B and point C shown in FIG. 2B are points where the recording layer of the optical disc 10 and the focus position of the laser light emitted from the pickup head 3 are in alignment.

  As described above, in the case of an optical disc having a single recording layer, there is one S-shaped signal obtained when the objective lens of the pickup head 3 is moved in the direction of approaching / separating the optical disc 10, and there are two recording layers. In the case of the optical disk, the two S-shaped signals obtained when the objective lens of the pickup head 3 is moved in the direction of approaching and separating from the optical disk 10 are two. Therefore, based on the number of S-shaped signals obtained when the objective lens of the pickup head 3 is moved toward and away from the optical disk 10, the recording layer of the optical disk 10 set in the main body is one layer or 2 Whether it is a layer can be determined. The number of S-shaped signals can be determined by setting a threshold value at a value slightly lower than the peak of the FE signal in the optical disk 10 having two recording layers and counting the number of peaks exceeding this threshold value.

  However, the FE signal shown in FIGS. 2A and 2B shows an FE signal obtained from an ideal optical disk 10 having no runout, and the optical disc 10 having runout has one recording layer. Even in such a case, the distance between the objective lens and the optical disc 10 changes due to surface deflection, so that the FE signal obtained when the objective lens of the pickup head 3 is moved in the direction of contacting or separating from the optical disc 10 is shown in FIG. The signal may be In this case, when the number of peaks exceeding the threshold value is counted for this signal, the number becomes two, and it is erroneously determined that the recording layer is a two-layer optical disk even though the recording layer is the one-layer optical disk 10. To do.

  In order to prevent this misjudgment, the optical disc apparatus 1 of this embodiment moves the objective lens of the pickup head 3 in the direction in which the pickup head 3 contacts and separates from the optical disc 10 to obtain the FE signal as shown below. Using the offset voltage of the FE signal corresponding to 10 surface shake, a recording layer number determination signal from which the influence of the surface shake of the optical disc has been removed is obtained. Then, the number of recording layers of the optical disc 10 is determined by counting the number of S-shaped signals with respect to the recording layer number determination signal.

  Hereinafter, an operation for determining the number of recording layers of the optical disc 10 will be described. The optical disc apparatus 1 of this embodiment performs a recording layer number determination process for determining whether the recording layer of the set optical disc 10 is one layer or two layers when the optical disc 10 is set in the apparatus main body. . FIG. 3 is a flowchart showing the recording layer number determination process. As described above, the recording layer number determination process is performed at the timing when the optical disc 10 is set in the apparatus main body, and the determination result is stored in a nonvolatile memory such as an EEPROM. Although this non-volatile memory is not shown, it is provided in the control unit 2. Therefore, even if the power is turned off while the optical disk 10 is set in the apparatus main body, this recording layer number determination process is performed again on the optical disk 10 set in the main body when the power is turned on after that. There is no need to do it.

  When the optical disk 10 is set in the apparatus main body, the optical disk apparatus 1 first drives the sled motor 4a to move the pickup head 3 to the outer peripheral side of the optical disk 10 (s1). Further, the spindle motor 7 is driven to rotate the optical disk 10 set in the main body at a lower speed than when reading or recording data. The optical disc apparatus 1 starts focus servo control and tracking servo control, and focuses on and tracks on the outermost track, preferably the outermost track, of the optical disc 10 rotating at a low speed (s2). When the focus is turned on, the focused position of the laser beam is matched with the recording layer of the optical disc 10, and when the track is turned on, the focused position of the laser beam is matched with the center of the track of the optical disc 10.

  When the focus is turned on and the track is turned on in s2, the optical disc apparatus 1 measures the amount of surface deflection with respect to the rotational position of the optical disc 10 set in the main body (s3). The measurement of the surface shake amount in s3 is performed in a state where the focus servo control is turned off and the objective lens is prohibited from moving in the direction in which the objective lens is in contact with or separated from the optical disc 10. On the other hand, the tracking servo control may or may not be turned off.

The optical disc apparatus 1 measures FE signals at a plurality of rotational positions of the optical disc 10 in s3. For example, as shown in FIG. 4A, 0 degrees (point A), 90 degrees (point B), 180 degrees (point C), and 270 degrees (point D) with reference to a certain rotational position of the optical disk 10. Measure the FE signal at 4 points. Here, the FE signal is measured at four points. However, the number of points is not limited to four, and may be five or more, or three or two.
However, if the number of points to be measured is reduced, the accuracy of the surface shake measurement signal with respect to the rotational position of the optical disc 10 by approximation in s4 described later will decrease, and conversely, if the number of points to be measured is increased, the time required for the measurement will increase. The number of points to be measured is preferably about 4 points. The rotational position of the optical disk 10 can be detected from the rotational angle of the spindle motor 7. Although the focus servo control is turned off, the objective lens is fixed at the position where the focus is turned on immediately before, so that the tracking servo control that is not turned off does not run out of control.

  When the optical disk apparatus 1 measures the FE signals at these four points (see FIG. 4B), the measured values of the FE signals at these four points correspond to the rotation angle of the optical disk 10, in other words, during one rotation of the optical disk 10. The change in the focus error signal is acquired as a surface shake measurement signal (s4). Specifically, an approximate curve of the FE signal measured in s3 is calculated, and this is acquired as a surface runout measurement signal. The processing relating to s3 and s4 corresponds to the first acquisition means referred to in the present invention.

  The surface shake measurement signal acquired in s4 is a signal corresponding to a change in the distance between the recording layer of the optical disc 10 and the objective lens of the pickup head 3 with respect to the rotational position of the optical disc 10. The cause of the change in the distance between the recording layer of the optical disc 10 and the objective lens of the pickup head 3 is the surface shake of the optical disc 10. Therefore, the surface shake measurement signal acquired in s4 is a signal corresponding to the amount of surface shake with respect to the rotational position of the optical disc 10, and can be said to be an offset voltage of the FE signal with respect to the rotational position of the optical disc 10.

  When the optical disc apparatus 1 acquires the surface shake measurement signal in s4, the optical disc device 1 moves the objective lens of the pickup head 3 in the direction of contacting and separating from the optical disc 10 and records the number of recording layers based on the FE signal at this time. Is obtained (s5). Specifically, the optical disc apparatus 10 uses a value obtained by subtracting the offset voltage of the FE signal obtained in s4 from the obtained FE signal according to the rotational position of the optical disc 10 as the recording layer number determination signal at the rotational position. get. Therefore, it is possible to obtain a recording layer number determination signal from which the influence of the surface shake due to the warp or the like of the optical disk 10 is removed. The processing relating to s5 corresponds to the second acquisition means referred to in the present invention. The tracking servo control is also turned off when the processing relating to s5 is executed.

  Then, the optical disc apparatus 1 counts the number of S-shaped signals with respect to the recording layer number determination signal obtained by removing the influence of the surface shake due to the warp of the optical disc 10 obtained in s5. Is one optical disc (s6, s7). On the contrary, if the number of S-shaped signals is two, it is determined that the recording layer is two optical disks (s6, s8). The optical disc apparatus 1 stores this determination result in a non-volatile memory provided in the control unit 2 and ends this process.

  As described above, the optical disc apparatus 1 according to this embodiment can determine whether the recording layer of the optical disc 10 is one layer or two layers in consideration of the surface shake of the optical disc 10. The number of layers can be properly determined. Therefore, even if the optical disc 10 has one recording layer or the optical disc 10 has two layers, data can be read and recorded appropriately, and the reliability of the apparatus main body can be reduced. Absent.

It is a figure which shows the structure of the principal part of the optical disk apparatus which is embodiment of this invention. It is a figure explaining the focus error signal obtained from an optical disk. 5 is a flowchart showing recording layer number determination processing in the optical disc apparatus according to the embodiment of the present invention. It is a figure explaining the recording layer number determination process in the optical disc device which is embodiment of this invention.

Explanation of symbols

1-optical disk device 2-control unit 3-pickup head 4-servo mechanism unit 4a-thread motor 5-recording unit 6-reproducing unit 7-spindle motor

Claims (3)

The optical disc having one or two recording layers set on the main body is rotated, and the optical disc is irradiated with a laser beam through an objective lens, and the reflected light is detected to record the optical disc. Reading means for reading data;
A lens moving means for moving the objective lens in a direction of moving toward and away from the optical disc;
At the time of reading data by the reading means, the lens moving means performs the lens moving means based on a focus error signal corresponding to the amount of deviation between the recording layer of the optical disc and the focus position of the laser light applied to the optical disc. In an optical disc apparatus provided with focus control means for controlling the movement of the objective lens and adjusting the in-focus position to the recording layer of the optical disc,
When an optical disk is set on the main body, a change in the focus error signal with respect to the rotational position of the optical disk set on the main body is acquired as a surface shake measurement signal in a state where the movement of the objective lens by the lens moving means is prohibited. 1 acquisition means;
While the optical disk is rotated, the objective lens is moved toward and away from the optical disk by the lens moving means . The focus error signal for the rotational position of the optical disk obtained at this time is Second acquisition means for acquiring a signal obtained by subtracting the surface shake measurement signal at the corresponding rotational position as a recording layer number determination signal;
Determination means for determining whether the recording layer of the optical disc set in the main body is one layer or two layers based on the recording layer number determination signal acquired by the second acquisition means;
Before SL first acquisition means, from the four focus error signal measured at the rotational position set at 90 degree intervals about the optical disk, estimates the change of the focus error signal during which one rotation of the optical disc, the so An optical disc apparatus which is means for obtaining a surface runout measurement signal. The optical disc having one or two recording layers set on the main body is rotated, and the optical disc is irradiated with a laser beam through an objective lens, and the reflected light is detected to record the optical disc. Reading means for reading data;
A lens moving means for moving the objective lens in a direction of moving toward and away from the optical disc;
At the time of reading data by the reading means, the lens moving means performs the lens moving means based on a focus error signal corresponding to the amount of deviation between the recording layer of the optical disc and the focus position of the laser light applied to the optical disc. In an optical disc apparatus provided with focus control means for controlling the movement of the objective lens and adjusting the in-focus position to the recording layer of the optical disc,
When an optical disk is set on the main body, a change in the focus error signal with respect to the rotational position of the optical disk set on the main body is acquired as a surface shake measurement signal in a state where the movement of the objective lens by the lens moving means is prohibited. 1 acquisition means;
While the optical disk is rotated, the objective lens is moved toward and away from the optical disk by the lens moving means . The focus error signal for the rotational position of the optical disk obtained at this time is Second acquisition means for acquiring a signal obtained by subtracting the surface shake measurement signal at the corresponding rotational position as a recording layer number determination signal;
Or recording layer of the optical disk by the second acquisition means is set in the main body on the basis of the recording layer number determination signal acquired is one layer, comprising: a determination unit configured to determine a two-layer, the Optical disk device.   The first acquisition unit estimates a change in the focus error signal during one rotation of the optical disk from a focus error signal measured at a plurality of rotational positions of the optical disk, and uses this as the surface shake measurement signal. Item 3. The optical disk device according to Item 2.

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