JP2007280528A - Optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk device in which address information can be read even when error correction of address information read out from an optical disk cannot be performed owing to damage, dirt, or the like, and it is prevented that data of the sector is lost for ever. <P>SOLUTION: A voltage level when jitter quantity of measured RF signals of PID1, 2 and jitter quantity of RF signals of PID3, 4 parts become the same and a fixed value or less is decided as a reference level. The control part 10 calculates bias applied to a TE signal output from a differential amplifier 6A so that this reference level becomes the prescribed voltage. The control part 10 calculates gain G of the amplifier 6C based on the measured TE signal and the reference level. The control part 10 applies calculated bias to the TE signal output from the differential amplifier 6A and sets gain G of the amplifier 6C to the calculated value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical disc apparatus that reads data recorded on an optical disc such as a DVD-RAM in which sector address information is pre-formatted and recorded at predetermined intervals and outputs a reproduction signal based on the read data. It is.

  2. Description of the Related Art Conventionally, there is an optical disk device that reads data recorded on an optical disk such as a DVD-RAM and outputs a reproduction signal (audio signal, video signal). In this optical disc apparatus, tracking servo control is performed to align the irradiation position of the laser beam with the center of the track of the optical disc. The DVD-RAM can be rewritten 100,000 times, and sector address information (CAPA) is preformatted and recorded in advance at predetermined intervals.

In a general optical disk apparatus, a four-divided photodetector having two light receiving elements arranged vertically and horizontally is provided in a pickup head. Further, the photodetector has a pair of left and right side spot light receiving elements arranged.
The optical disk apparatus performs the tracking servo control using a difference signal (hereinafter referred to as a tracking error signal) between both reflected light amounts detected by a pair of left and right light receiving elements. As is well known, the tracking error signal is a signal indicating the amount of deviation between the irradiation position of the laser beam and the center of the track of the optical disk, and is a signal having the characteristics shown in FIG. In this figure, the horizontal axis is the amount of displacement of the objective lens, and the right direction is the outer peripheral direction of the optical disk.

When reading data from an optical disk, the larger the reproduction signal (RF signal), the higher the reading ability. Therefore, tracking servo control of a general optical disk apparatus is performed as follows.
In tracking servo control, the point at which the RF signal (the amount of reflected light from the optical disc detected by the photodetector), which is the sum of the outputs of the four light receiving elements, becomes the maximum is set as the reference point (Vref) (see FIG. 8). The objective lens is displaced so that the magnitude of the tracking error signal is the reference point.

  Ideally, the reference point is the center O in the tracking error signal (see FIG. 8B), but in reality, the reference point is deviated from the center O due to the accuracy of optical components and the like constituting the pickup head. (See FIGS. 8A and 8C) The tracking error signal is not well balanced. When tracking servo control is performed using the tracking error signal shown in FIGS. 8A and 8C, tracking is easily lost, and the tracking servo control becomes unstable. Here, “out of tracking” means a state where the objective lens has moved to a position where a tracking error signal cannot be obtained.

Therefore, in the conventional optical disc apparatus, the tracking servo control is performed after adjusting the balance of the tracking error signal so that the maximum value and the minimum value of the tracking error signal with respect to the reference level are substantially the target with the reference level interposed therebetween. Do.
On the other hand, there has been proposed an optical disc apparatus that reduces the diffuse reflection component from the optical disc caused by tilting and increases the amount of reflected light from the optical disc detected by a photodetector (see Patent Document 1).
JP 2000-306253 A

On the recording surface of an optical disk, scratches, dirt, etc. often occur due to the use of the optical disk. In particular, the DVD-RAM is expected to be used for a long period of 100,000 rewrites, so that scratches and dirt are often generated. When the scratches and dirt increase, the RF signal contains a lot of jitter.
Here, the jitter amount generated in the RF signal and the error rate of the reproduction data have a close relationship. Specifically, when the jitter amount is small, the error rate is small, and when the jitter amount is large, the error rate is large. If the error rate of the address information exceeds a predetermined value, it becomes impossible to correct the error of the address information. Here, the predetermined value is the maximum error rate that can be corrected by an error, and takes a different value depending on the encoding method.

Therefore, in the conventional optical disk apparatus, there is a case where the address information read from the optical disk cannot be error-corrected due to jitter due to scratches or dirt on the recording surface of the optical disk. The fact that the address information cannot be error-corrected means that the data in the sector cannot be read.
Therefore, there is a problem that data such as photographs recorded on the optical disk by the user is permanently lost.

  The present invention is intended to solve such a conventional problem. Even when the address information read from the optical disk cannot be error-corrected due to scratches or dirt, the address information can be read and the sector can be read. An object of the present invention is to provide an optical disc apparatus that prevents the data from being permanently lost.

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

(1) When an optical disk on which address information of each sector is preformatted and recorded in advance at a predetermined interval is set in the apparatus body, the optical disk is irradiated with laser light through an objective lens, and the reflected light A pickup head that reads a signal recorded on the optical disc by detecting the light by a photodetector;
Reproducing means for correcting and outputting a reproduction signal based on a signal read from the optical disc by the pickup head,
The address information of the optical disk is composed of first address information located on the inner circumference of the ½ track and second address information located on the outer circumference of the ½ track with respect to the land or the groove,
In the optical disc apparatus in which the photodetector of the pickup head is divided into a first area and a second area by at least two light receiving elements,
When the optical disc is mounted, the reproduction signal output from the reproduction means is measured, and the first jitter amount of the reproduction signal from the first address information of the optical disc detected by the photodetector is detected by the photodetector. A reference level determination function for setting a voltage level when the second jitter amount of the reproduction signal from the second address information of the optical disc is equal to or less than a predetermined value as a reference level;
When the optical disc is mounted, the objective lens is moved in the radial direction, and the reflected light amount detected by the light receiving element in the first region and the reflected light amount detected by the light receiving element in the second region The tracking error signal is measured as a tracking error signal, and for the measured tracking error signal, the maximum value and the minimum value of the tracking error signal with respect to the reference level determined by the reference level determination function determine the reference level. A balance adjustment function for adjusting the balance of the tracking error signal so as to be substantially the target,
Tracking servo means having
The tracking servo means performs tracking servo control on the movement of the objective lens by using the tracking error signal balance-adjusted by the balance adjustment function.

In this configuration, it is assumed that the recording surface of the optical disk is damaged or dirty due to the use of the optical disk. Here, the optical disk is, for example, a DVD-RAM. The constant value is a limit amount of jitter that can be read by error correcting both pieces of address information. The constant value is a value determined in advance in relation to a predetermined value of the error rate of the address information read from the optical disc. The predetermined value is the maximum value of the error rate that can be corrected, and takes a different value depending on the encoding method.
If the error rate of the address information exceeds a predetermined value, that is, if the jitter amount of the address information exceeds a certain value, the reproducing unit cannot correct the error of the address information. That is, the reproducing means cannot read the data in that sector.
In this configuration, the voltage level when the tracking servo means has the same jitter amount of both the address information and below a predetermined value is defined as the reference level. The tracking servo means adjusts the balance of the tracking error signal based on the reference level, and performs tracking servo control using the adjusted tracking error signal. When the optical disk is reproduced under this circumstance, the balance is adjusted in both address information parts, so that the error rate of both address information parts becomes extremely smaller than that of the conventional optical disk apparatus. That is, the reproducing means can read accurate address information.
Therefore, the reading ability of the address information portion on the optical disc is improved. Specifically, in the conventional optical disk device, the error rate of the address information read from the optical disk is high. Therefore, even when the address information cannot be corrected, the error rate of the address information becomes low in this configuration, and the error Can be corrected. That is, the address information can be read, and sector data is prevented from being permanently lost. Therefore, the reliability of the apparatus is improved.

(2) The reference level determination function of the tracking servo means samples the first jitter amount and the second jitter amount by a predetermined number of sectors, and calculates an average value of the jitter amount per sector. Each is calculated, and the voltage level when both average values are the same and below a certain value is defined as the reference level.

In this configuration, the predetermined number of sectors is, for example, 10 sectors.
Both address information exists over the entire circumference of the optical disk. In this configuration, since the reference level is determined from many sectors, the error rate of both address information portions when the optical disc is reproduced is smaller than the above (1) when viewed in total over the entire circumference of the optical disc.
Therefore, the reading ability of the address information portion on the optical disc is further improved. The reliability of the device is further improved.

(3) A switching means for switching whether to enable or disable the reference level determination function is provided.

In this configuration, when the switching means is disabled, the tracking servo means measures the reproduction signal output by the reproduction means when the optical disc is mounted, and determines the voltage level at which the reproduction signal is maximized as the reference level. That is, the tracking servo means determines the reference level as in the conventional optical disc apparatus. The tracking servo means adjusts the balance of the tracking error signal based on the reference level, and performs tracking servo control using the adjusted tracking error signal.
In this configuration, the user can switch whether the reference level determination function is enabled or disabled by the switching unit. In the above (1) and (2), it is determined to be valid, but here, the user can select either valid or invalid.
As a general usage method, the user normally disables the reference level determination function, and enables the reference level determination function in the event of an error in which the address information read from the optical disc cannot be corrected due to scratches or dirt. To do.
Therefore, since the user can switch whether to enable or disable the reference level determination function according to his / her own usage method, user convenience can be improved.

  According to the present invention, the reading ability of the address information portion on the optical disc is improved. In addition, the reliability of the apparatus is improved.

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

  FIG. 1 is a block diagram showing a configuration of a main part of an optical disc apparatus according to an embodiment of the present invention. The optical disk apparatus 1 of this embodiment is a DVD player, and includes a control unit 10 that controls the apparatus main body, a pickup head 2 that irradiates the optical disk 100 set in the apparatus main body with laser light, and detects the reflected light. An RF amplifier 3 that generates an RF signal based on the reflected light, an error signal generation unit 6 that generates an error signal based on the reflected light, a servo circuit 4 that generates a drive signal based on the error signal, A driver circuit 5 that performs servo control based on a drive signal, a reproduction unit 7 that outputs a reproduction signal, a ROM 8, and an operation unit 9 are provided.

  In this embodiment, a DVD player is described, but the present invention can also be applied to a DVD recorder.

  The pickup head 2 includes a laser diode (LD), a collimator lens, a beam splitter, an objective lens, a photodetector, a thread motor, and a biaxial actuator (not shown).

  The pickup head 2 is movably attached to an axis extending in the radial direction of the optical disc 100, similarly to a known optical disc apparatus. The sled motor moves the pickup head 2 in the radial direction of the optical disc 100.

  The LD is a light source that outputs laser light, and the photodetector is formed of a plurality of light receiving elements, and detects (photoelectric conversion) reflected light from the optical disc 100.

  The objective lens adjusts the irradiation position of the laser beam on the optical disc 100. The biaxial actuator moves the objective lens in the direction in which the objective lens is brought into contact with and separated from the optical disc 100 and in the radial direction of the optical disc 100.

  The error signal generator 6 generates a focus error signal (hereinafter referred to as “FE”) based on the reflected light from the optical disc 100 detected by a plurality of light receiving elements constituting a photodetector 11 (see FIG. 4 described later) provided in the pickup head 2. The signal is referred to as a “signal” and is output to the servo circuit 4. In addition, the error signal generation unit 6 is a tracking error signal (hereinafter, referred to as “tracking error signal”) based on the reflected light from the optical disc 100 detected by a plurality of light receiving elements constituting a photodetector 11 (see FIG. 4 described later) provided in the pickup head 2. This is referred to as a “TE signal”) and is output to the servo circuit 4.

  The servo circuit 4 sets the value of the focusing drive signal and TE signal to 0 (reference level) to 0 (reference level) based on the FE signal and TE signal output from the error signal generation unit 6. The tracking drive signal for generating () is generated and output to the driver circuit 5.

  The driver circuit 5 gives a focusing drive signal to the actuator, moves the objective lens of the pickup head 2 in the optical axis direction with respect to the optical disc 100, and performs focus servo control to focus the laser beam on the recording surface of the optical disc 100. The driver circuit 5 gives a tracking drive signal to the actuator, moves the objective lens of the pickup head 2 in the radial direction of the optical disc 100, and performs tracking servo control to irradiate the center of the track of the optical disc 100 with laser light.

  By performing the focus servo control and the tracking servo control, the laser beam can be made to follow a desired track, and the laser beam can be focused on this track.

  During reproduction, the pickup head 2 irradiates the optical disc 100 with a laser beam having a reading power, and detects reflected light from the optical disc 100 with a photodetector 11 (see FIG. 4 described later). Thereby, the information recorded on the optical disc 100 is optically read.

  The RF amplifier 3 generates an RF signal based on the reflected light from the optical disc 100 detected by a plurality of light receiving elements A to D (see FIG. 4 described later) constituting the photodetector 11 provided in the pickup head 2, Is amplified, waveform equalized, etc., and output to the reproduction unit 7. The RF signal is a read signal for data recorded on the optical disc 100.

  The playback unit 7 demodulates the RF signal, extracts video and audio data, corrects an error, decodes it, generates a playback signal, and outputs it to the outside. This data can be error-corrected by a Reed-Solomon code, for example. A predetermined value of the error rate is determined by this encoding method. Further, this data is encoded by, for example, MPEG.

  The ROM 8 stores a control program.

  The control unit 10 is a microcomputer, for example. The control unit 10 includes a RAM 10A as a work field for developing a control program and the like. The control unit 10 acquires address information (PID1 to PID4) described later from the reproduction unit 7.

  The operation unit 9 is used by a user to input various commands (commands) to the optical disc apparatus 1, and is provided with a reproduction key, a special reproduction key, a stop key, and the like. A command input by the user to the optical disc apparatus 1 is transmitted to the control unit 10. The operation unit 9 includes a remote control signal detection unit (not shown). The user inputs a command to the remote control signal detection unit from the outside using a remote control (not shown).

  Here, the control unit 10, the error signal generation unit 6, the servo circuit 4, and the driver circuit 5 correspond to the “tracking servo means” of the present invention. The control unit 10, the RF amplifier 3, and the reproduction unit 7 correspond to the “reproduction unit” of the present invention.

  Next, the structure of the DVD-RAM will be described.

  FIG. 2 is a conceptual diagram showing the format of an arbitrary sector on the optical disc 100. Since the optical disc 100 is a so-called DVD-RAM, it includes a land track and a groove track. The land track and groove track are divided into a plurality of sectors, and data is recorded on both.

As shown in FIG. 2, the sector is divided into a data area where data such as video and audio is recorded, and an address area where sector address information is pre-formatted and recorded. In the sector address information, a physical address on the optical disc 100, that is, a sector number or a sector position is recorded.
Furthermore, the address area is divided into a header area and a mirror area consisting only of the mirror surface. The header area consists of areas of PID (Physical ID) 1 to 4.

  PID1 to PID4 are address information preformatted in advance on the optical disc 100 at predetermined intervals. The preformat is an embossing process, for example.

  PIDs 1 and 2 are arranged in the header area before the data area of the groove while being displaced from the groove center to the outer peripheral side by ½ of the groove width. PIDs 3 and 4 are arranged in the header area before the data area of the groove while being displaced from the groove center to the inner circumference side by a half of the groove width. As a result, in the header area before the data area of the land, the PID 1 and 2 of the header recording area of the recording track of the groove on the inner periphery side of one recording track of the land are located at the positions of PID 3 and 4 , The PIDs 3 and 4 in the header area of the recording track of the groove on the outer circumference of one of the recording tracks on the land are displaced from the center of the groove on both sides to the track side of the land by ½ of the groove width. Become a shape.

FIG. 3 is a diagram showing an overview of an arbitrary sector in the optical disc 100. The laser light emitted from the pickup head 2 travels from left to right as indicated by the arrows in FIG.
The current sector area 110 is an area including a sector that is currently irradiated with laser light. Address area 111 includes PIDs 1 to 4. The data area 112 includes lands 112A and grooves 112B. The previous sector area 101 is an area including a sector irradiated with laser light immediately before the current sector area 110. The previous sector area 101 also has a data area 102.

  As shown in FIG. 3, the sector currently irradiated with the laser beam is a sector in the land track. This sector is composed of address information PID1, 2 or PID3, 4 and a land 112A in which data such as video and audio is recorded.

  Here, the first address information corresponds to “PID1, 2” of the present invention. The second address information corresponds to “PID3, 4” of the present invention.

  In this embodiment, the optical disk 100 is a DVD-RAM. However, the present invention is not limited to this, and any optical disk may be used as long as sector address information is pre-formatted and recorded at predetermined intervals.

  FIG. 4 is a diagram showing a photodetector provided in the pickup head. The pickup head 2 is provided with a four-divided photodetector 11 in which four light receiving elements A to D are arranged two by two vertically and horizontally (see FIGS. 1 and 4). Further, the photodetector 11 has a pair of left and right side spot light receiving elements E and F arranged.

  FIG. 5 is a diagram illustrating an example of a circuit configuration of the RF amplifier and the error signal generation unit of the optical disc apparatus according to the embodiment of the present invention. The outputs of the light receiving elements A to D are input to the RF amplifier 3. As shown in FIG. 5, the RF amplifier 3 includes an adder 3A for adding outputs from the light receiving elements A and D, an adder 3B for adding outputs from the light receiving elements B and C, and an adder. An amplifier 3C for amplifying the output of 3A, an amplifier 3D for amplifying the output of adder 3B, an adder 3E for outputting an RF signal obtained by adding the outputs of amplifier 3C and amplifier 3D, and the RF output from adder 3E And an amplifier 3F for amplifying the signal.

  On the other hand, the output of the light receiving elements E and F is input to the error signal generation unit 6. The error signal generator 6 includes an amplifier 6C that amplifies the output of the light receiving element E, an amplifier 6B that amplifies the output of the light receiving element F, and a differential amplifier that outputs a TE signal that is the difference between the outputs of the amplifier 6B and the amplifier 6C. 6A. The gain of the amplifier 6C is adjusted by the control unit 10.

This circuit configuration is merely an example, and other circuit configurations may be adopted. For example, in this embodiment, only the gain of the amplifier 6C is adjusted, but the amplifier 6B can also be adjusted, and the gains of the amplifiers 6B and 6C may be individually adjusted by the control unit 10.
Although not shown in FIG. 5, the error signal generator 6 is provided with a bias application circuit that applies a bias to the TE signal in order to adjust the offset of the TE signal. The servo circuit 4 receives a TE signal to which a bias is applied by the bias application circuit.
Although not shown in FIG. 5, the error signal generation unit 6 is also provided with a circuit that processes a signal input from the pickup head 2 and generates an FE signal input to the servo circuit 4. This circuit may be a circuit that processes the outputs of the four light receiving elements A to D to generate an FE signal. Since these circuits are well known, description thereof is omitted here.

  The operation of the optical disc apparatus 1 according to the embodiment of the present invention will be described below.

  FIG. 6 is a flowchart showing an operation performed when the control unit of the optical disc apparatus according to the embodiment of the present invention mounts the optical disc. The control unit 10 executes a balance adjustment process for adjusting the balance of the TE signal when the optical disc 100 is mounted. The optical disk 100 is mounted when the optical disk 100 is set in the main body, or when a playback command is input while the optical disk 100 is set in the apparatus main body 1.

  The control unit 10 sets the gain of the amplifier 6C to a preset size X (s1) and measures the TE signal (s2). s2 is a process of measuring the waveform of the TE signal output from the differential amplifier 6A while moving the objective lens of the pickup head 2 in the radial direction of the optical disc 100.

  FIG. 7 is a diagram illustrating a change of the TE signal measured during the TE signal measurement with respect to the displacement amount of the objective lens. As is well known, when the objective lens is moved in the radial direction of the optical disc 100, the TE signal shown in FIG. 7 is measured. In FIG. 7, the horizontal axis indicates the amount of displacement of the objective lens.

  Further, the control unit 10 measures the reproduction signals of the PID 1, 2 and PID 3, 4 portions in an arbitrary sector (s3). s3 is a reproduction signal (RF signal) output from the amplifier 3F while moving the objective lens of the pickup head 2 in the radial direction of the optical disc 100 or in the direction of moving toward or away from the optical disc 100. ) To measure the waveform. The RF signal measured in s3 is an RF signal after waveform equalization.

  In this embodiment, the RF signal after waveform equalization in s3 is used as a reproduction signal to be measured, but an RF signal before waveform equalization may be used. Further, data-clock phase difference jitter may be measured from a binarized (EFM data) signal before error correction.

Here, the control unit 10 has a reference level determination function and a balance adjustment function.
The control unit 10 uses the reference level determination function so that the first jitter amount of the RF signals of PID1 and 2 measured in s3 and the second jitter amount of the RF signal of the PID3 and 4 portions are the same and less than a certain value The voltage level when the value becomes is defined as the reference level. Then, the control unit 10 calculates a bias to be applied to the TE signal output from the differential amplifier 6A so that the reference level becomes a predetermined voltage, for example, 0 V (s4).

Here, the fixed value is a limit amount of jitter that can be read by error-correcting PID 1, 2 or PID 3, 4. The constant value is a value determined in advance in relation to a predetermined value of the error rate of PID 1 or 2 or PID 3 or 4 read from the optical disc 100. The predetermined value is the maximum value of the error rate that can be corrected, and takes a different value depending on the encoding method. If the error rate of PID 1, 2 or PID 3, 4 exceeds a predetermined value, error correction of PID 1, 2 or PID 3, 4 read by the pickup head 2 cannot be performed.
The reason for making the first jitter amount and the second jitter amount the same in s4 is to reduce the error rates of both PID1, 2 and PID3, 4 in all sectors of the optical disc 100. is there. Thereby, in all sectors of the optical disc 100, the error rate of any one of PID1, 2 and PID3, 4 is extremely improved, and the other is not extremely deteriorated.

  FIG. 8 is a diagram for explaining a TE signal whose bias has been adjusted. When the bias calculated in s4 is applied to the TE signal output from the differential amplifier 6A, for example, the TE signal when the point A shown in FIG. 7 is a reference level has the waveform shown in FIG. When the point B shown in FIG. 8 is used as a reference level, the TE signal has the waveform shown in FIG. 8B, and when the point C shown in FIG. 7 is used as the reference level, the TE signal has a waveform shown in FIG. .

  The controller 10 turns off the servo circuit 4 (s5). Thereby, the movement of the objective lens of the pickup head 2 is restricted.

  The control unit 10 calculates the gain G of the amplifier 6C (s6). The calculation of the gain G relating to s6 is performed as follows.

  The control unit 10 sets the potential difference between the maximum value of the TE signal measured at s2 and the reference level and the potential difference between the minimum value of the TE signal measured at s2 and the reference level to a preset potential difference V. Then, the gain G of the amplifier 6C is calculated.

The control unit 10 applies the bias calculated in s4 to the TE signal output from the differential amplifier 6A by the balance adjustment function, and sets the gain G of the amplifier 6C to the value calculated in s6 (s7). Here, when the potential difference V does not occur, the gains of the amplifiers 6A and 6B may be adjusted. After s7, the control unit 10 turns on the servo circuit 4 that was turned off in s5 (s8), starts tracking control (s9), and starts a reproduction operation after the track is turned on (s10).
The controller 10 records the calculated tracking balance value in the RAM 10A.

  When the processing of s7 is completed, the balance of the TE signal output from the differential amplifier 6A is adjusted in the control unit 10, and the maximum value and the minimum value are set as described above as shown in the waveform of FIG. It is almost the target with the reference level in between. Therefore, in the reproduction operation executed in s10, tracking control is performed using the TE signal whose balance is adjusted. During the reproducing operation, the balance adjustment is performed at the PID1, 2 and PID3, 4 portions, so that the error rate at the PID1, 2 and PID3, 4 portion is extremely smaller than that of the conventional optical disc apparatus. That is, the reproducing unit 7 can read out the correct PIDs 1 and 2 and PIDs 3 and 4.

  Therefore, the reading ability of the PID 1, 2 and PID 3, 4 portions on the optical disc 100 is improved. Specifically, in the conventional optical disk device, the error rate of PID1, 2 and PID3, 4 read from the optical disk 100 is high, so even if PID1, 2 and PID3, 4 cannot be error corrected, The error rates of the PIDs 1 and 2 and PIDs 3 and 4 are lowered, and error correction can be performed. That is, the PID1, 2 and PID3, 4 can be read, and the sector data is prevented from being permanently lost. Therefore, the reliability of the apparatus is improved.

In s2, the control unit 10 preferably measures the TE signals of all PID1, 2 and PID3, 4 portions in an arbitrary sector, as in s3. More preferably, it is the same sector as s3. Thereby, the reading ability of PID1, 2 and PID3, 4 part in the optical disc 100 is further improved. Specifically, the error rate of PID1, 2 and PID3,4 is further reduced by the balance adjustment. Therefore, the reliability of the apparatus is further improved.
The tracking servo means balance adjustment function adjusts the balance of the TE signal in a servo-off state in which the movement of the objective lens is restricted. That is, since the gain G and bias of the amplifier 6C are adjusted with the servo circuit 4 turned off, the servo circuit 4 temporarily operates with an inappropriate gain during gain adjustment, and the objective lens is displaced. Therefore, it is possible to reliably prevent the objective lens from colliding with the optical disk 100 during gain adjustment (TE signal balance adjustment) and damage.

  Moreover, the following modifications can be employed in the embodiment of the present invention.

(First modification)
In s3 and s4 in FIG. 6, the first jitter amount and the second jitter amount are sampled by a predetermined number of sectors, and the average value of the jitter amount per sector is calculated, and both average values are the same. In addition, the voltage level when it becomes a certain value or less may be determined as the reference level. The predetermined number of sectors is, for example, 10 sectors.
PID 1 to 4 exist over the entire circumference of the optical disc 100. In this configuration, since the reference level is determined from many sectors, the error rate of the PID1 to PID4 portion when the optical disc 100 is reproduced is smaller than that in the above embodiment when viewed in total over the entire circumference of the optical disc 100. .
Therefore, the reading ability of the PID 1 to 4 portions in the optical disc 100 is further improved. The reliability of the device is further improved.

(Second modification)
The operation unit 9 may be provided with a switching key for switching between enabling and disabling the reference level determination function of the control unit 10 (see FIG. 1). When the switching key is disabled, the control unit 10 measures the reproduction signal output from the amplifier 3F of the RF amplifier 3 at s3 and s4 in FIG. 6, and determines the voltage level at which the reproduction signal is maximized as a reference level. It is determined. That is, the control unit 10 disables the reference level determination function and determines the reference level as in the conventional optical disc apparatus. Then, the control unit 10 adjusts the balance of the TE signal based on the reference level in s7 of FIG. 6, and performs tracking servo control using the TE signal adjusted in s9 and s10 of FIG.
In the second modified example, the user can switch between enabling and disabling the reference level determination function with the switch key.
As a general usage method, the user normally disables the reference level determination function, and enables the reference level determination function when PID 1, 2 or PID 3, 4 cannot be error-corrected due to scratches or dirt. .
Therefore, since the user can switch whether to enable or disable the reference level determination function according to his / her own usage method, user convenience can be improved.

Here, the control unit 10 and the operation unit 9 correspond to the “switching unit” of the present invention.
The second modification can also be applied to the first modification.

1 is a block diagram showing a configuration of a main part of an optical disc apparatus according to an embodiment of the present invention. Conceptual diagram showing the format of an arbitrary sector in the optical disc 100 The figure which shows the general view of the arbitrary sectors in the optical disk 100 The figure which shows the photodetector provided in the pickup head The figure which shows an example of the circuit structure of RF amplifier and the error signal generation part of the optical disk apparatus which is embodiment of this invention 7 is a flowchart showing an operation performed when the control unit of the optical disc apparatus according to the embodiment of the present invention mounts an optical disc. The figure which shows the change with respect to the displacement amount of the objective lens of TE signal measured at the time of TE signal measurement FIG. 6 is a diagram for explaining a bias-adjusted TE signal.

Explanation of symbols

1-optical disk device 2-pickup head 3-RF amplifier 4-servo circuit 5-driver circuit 6-error signal generator 7-reproducing unit 8-ROM
9-Operation section 10-Control section 11-Photo detector 100-Optical disk 110-Sector area 111-Address area 112-Data area

Claims (4)

When an optical disc in which address information of each sector is pre-formatted and recorded in advance at a predetermined interval is set in the main body of the apparatus, the optical disc is irradiated with a laser beam through an objective lens, and the reflected light is irradiated by a photodetector. A pickup head that reads a signal recorded on the optical disc by detecting;
Reproducing means for correcting and outputting a reproduction signal based on a signal read from the optical disc by the pickup head,
The address information of the optical disk is composed of first address information located on the inner circumference of the ½ track and second address information located on the outer circumference of the ½ track with respect to the land or the groove,
In the DVD player in which the photodetector of the pickup head is divided into a first area and a second area by at least two light receiving elements,
When the optical disc is mounted, the reproduction signal output from the reproduction means is measured, and the first jitter amount of the reproduction signal from the first address information of the optical disc detected by the photodetector is detected by the photodetector. The second jitter amount of the reproduction signal from the second address information of the optical disc is sampled for a predetermined number of sectors, and the average value of the jitter amount per sector is calculated, and both average values are A reference level determination function that determines a voltage level as a reference level when the same and below a certain value;
When the optical disc is mounted, the objective lens is moved in the radial direction, and the reflected light amount detected by the light receiving element in the first region and the reflected light amount detected by the light receiving element in the second region The tracking error signal is measured as a tracking error signal, and for the measured tracking error signal, the maximum value and the minimum value of the tracking error signal with respect to the reference level determined by the reference level determination function determine the reference level. A balance adjustment function for adjusting the balance of the tracking error signal so as to be substantially the target,
Tracking servo means having
Switching means for switching whether to enable or disable the reference level determination function,
The tracking servo means is a DVD player that performs tracking servo control of the movement of the objective lens using the tracking error signal that has been balance-adjusted by the balance adjustment function. When an optical disc in which address information of each sector is pre-formatted and recorded in advance at a predetermined interval is set in the main body of the apparatus, the optical disc is irradiated with a laser beam through an objective lens, and the reflected light is irradiated by a photodetector. A pickup head that reads a signal recorded on the optical disc by detecting;
Reproducing means for correcting and outputting a reproduction signal based on a signal read from the optical disc by the pickup head,
The address information of the optical disk is composed of first address information located on the inner circumference of the ½ track and second address information located on the outer circumference of the ½ track with respect to the land or the groove,
In the optical disc apparatus in which the photodetector of the pickup head is divided into a first area and a second area by at least two light receiving elements,
When the optical disc is mounted, the reproduction signal output from the reproduction means is measured, and the first jitter amount of the reproduction signal from the first address information of the optical disc detected by the photodetector is detected by the photodetector. A reference level determination function for setting a voltage level when the second jitter amount of the reproduction signal from the second address information of the optical disc is equal to or less than a predetermined value as a reference level;
When the optical disc is mounted, the objective lens is moved in the radial direction, and the reflected light amount detected by the light receiving element in the first region and the reflected light amount detected by the light receiving element in the second region The tracking error signal is measured as a tracking error signal, and for the measured tracking error signal, the maximum value and the minimum value of the tracking error signal with respect to the reference level determined by the reference level determination function determine the reference level. A balance adjustment function for adjusting the balance of the tracking error signal so as to be substantially the target,
Tracking servo means having
The tracking servo means is an optical disc apparatus that performs tracking servo control of the movement of the objective lens using the tracking error signal balance-adjusted by the balance adjustment function.   The reference level determination function of the tracking servo means samples the first jitter amount and the second jitter amount by a predetermined number of sectors, and calculates an average value of the jitter amount per sector. 3. The optical disc apparatus according to claim 2, wherein a voltage level when both average values are equal and equal to or less than a predetermined value is defined as a reference level.   4. The optical disc apparatus according to claim 2, further comprising a switching unit that switches between enabling and disabling the reference level determination function.

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