WO2014097394A1

WO2014097394A1 - Disk reproduction device and focus servo pulling-in method

Info

Publication number: WO2014097394A1
Application number: PCT/JP2012/082803
Authority: WO
Inventors: 平井　伸明
Original assignee: 三菱電機株式会社
Priority date: 2012-12-18
Filing date: 2012-12-18
Publication date: 2014-06-26

Abstract

This disk reproduction device includes a focus driving setting unit (7) that holds a driving amount and a driving speed of an objective lens in focus servo pulling-in operations, the driving amount and the driving speed being optimized for disk types, respectively, so as to set a driving amount and a driving speed of the objective lens corresponding to the disk type of a disk (d) as a reproduction object with respect to a servo DSP (2). With respect to the servo DSP (2), a driving amount and a driving speed of the objective lens corresponding to the disk type determined by a microcomputer (4) for control are set by the focus driving setting unit (7), so that the servo DSP (2) performs a focus servo pulling-in operation with the driving amount and the driving speed of the objective lens corresponding to the disk type of the disk (d) as the reproduction object.

Description

Disc reproducing apparatus and focus servo pull-in method

The present invention relates to a disk reproducing apparatus and a focus servo pull-in method for performing appropriate focus servo pull-in according to the type of the disk.

For example, Patent Document 1 discloses an apparatus that discriminates the type of an optical disc and performs focus servo pull-in from an optimum position corresponding to the discriminated type.

JP-A-10-55547

In the conventional technique represented by Patent Document 1, the focus servo pull-in is performed by determining the drive amount of the objective lens of the optical pickup based on the type of the disk, thereby reducing the time required for the focus servo pull-in. Yes.
However, since an appropriate driving speed of the objective lens according to the type of the disk is not considered, there is a problem that the time required for the focus servo pull-in cannot be further shortened.

The present invention has been made in order to solve the above-described problems, and provides a disk reproducing apparatus and a focus servo pull-in method that can shorten the time required for the focus servo pull-in operation according to the type of the disk. Objective.

The disc reproducing apparatus according to the present invention includes an optical pickup that collects a light beam on a recording surface of a disc with an objective lens, and a focus that operates a focus servo by moving the objective lens to a position that focuses on the recording surface of the disc. Servo pull-in, servo processing unit that generates discriminating data used to discriminate disc type based on the reflected light component of the light beam received by the optical pickup from the disc, discriminating disc type using the discriminating data In the disk reproducing apparatus including the control unit, the objective lens driving amount and the driving speed in the focus servo pull-in optimized for each disk type are held, and the objective lens driving according to the disk type of the disk to be reproduced is performed. A focus drive setting unit that sets the amount and drive speed in the servo processing unit, The robot processing unit sets the driving amount and driving speed of the objective lens according to the disc type determined by the control unit from the focus drive setting unit, and drives the objective lens according to the disc type of the disc to be reproduced. The focus servo pull-in is performed by the amount and the driving speed.

According to the present invention, there is an effect that the time required for the focus servo pull-in operation can be shortened according to the disc type.

It is a block diagram which shows the structure of the conventional disc reproducing | regenerating apparatus. It is a flowchart which shows operation | movement of the conventional disc reproducing | regenerating apparatus. It is a figure which shows the relationship between the focus drive signal and focus error signal in the conventional focus servo pull-in operation. It is a block diagram which shows the structure of the disc reproducing | regenerating apparatus concerning Embodiment 1 of this invention. 4 is a flowchart showing an operation of the disc reproducing apparatus according to the first embodiment. 6 is a diagram illustrating a relationship between a focus drive signal and a focus error signal in the focus servo pull-in operation according to Embodiment 1. FIG. It is a figure which shows the relationship between the focus drive signal and focus error signal in the focus servo pull-in operation | movement of Embodiment 2 of this invention.

Hereinafter, in order to describe the present invention in more detail, modes for carrying out the present invention will be described with reference to the accompanying drawings.
Embodiment 1 FIG.
First, focus servo pull-in in a conventional disk reproducing apparatus will be described.
FIG. 1 is a block diagram showing a configuration of a conventional disk reproducing apparatus. In FIG. 1, an optical pickup (PU) 100 condenses a light beam on a recording (pit) surface of a disk d with an objective lens, and receives a reflected light component of the light beam as an information signal.
Although not shown in FIG. 1, the optical pickup 100 reproduces a CD and a DVD. For example, an optical pickup for reproducing a DVD having a laser diode, an optical element, and a photoelectric conversion circuit suitable for reproducing the DVD, and reproducing the CD. And a CD reproducing optical pickup having a photoelectric conversion circuit.
The optical pickup 100 includes a focus actuator that drives the objective lens in the focus direction and a tracking actuator that drives the objective lens in the tracking direction. The information signal read from the disk d by the optical pickup 100 is supplied to the DVD / CD reproduction circuit 102 via the servo DSP 101.

A servo DSP (Digital Signal Processor) 101 is a servo processing unit that performs a focus servo pull-in process and a tracking servo pull-in process. That is, the servo drive output from the servo DSP 101 is amplified by the PU / motor drive circuit 104 and becomes a drive signal for driving the two actuators of the optical pickup 100 and the disk motor 105 for rotating the disk d. As a result, the disk d is rotated, the objective lens of the optical pickup 100 is moved in the focus direction by the focus actuator, the focus servo pull-in process is executed, and the objective lens is moved in the tracking direction by the tracking actuator. Servo pull-in processing is executed.
The control microcomputer 103 controls the operation of the servo DSP 101. For example, the control microcomputer 103 determines the disk type of the disk d to be reproduced from the signal read by the optical pickup 100 from the disk d, and causes the servo DSP 101 to execute a focus servo pull-in process and a tracking servo pull-in process.

FIG. 2 is a flowchart showing the operation of the conventional disk reproducing apparatus.
First, when the disk d is inserted into the disk playback apparatus and the playback start of the disk d is started, the control microcomputer 103 instructs the servo DSP 101 to connect the optical pickup 100 and the disk motor 105 to the PU / motor drive circuit 104. Drive with.
Next, the servo DSP 101 processes the signal output from the optical pickup 100 to generate disc type determination data. The control microcomputer 103 acquires the discrimination data generated by the servo DSP 101 (step ST100).
Here, the discrimination data is data corresponding to the disc type generated based on the reflected light component of the light beam received by the optical pickup 100 from the disc d. For example, the reflected light component received by the optical pickup 100 The amplitude of the focus error signal, tracking error signal, and total light quantity sum signal generated from

The control microcomputer 103 determines whether the disk d inserted into the disk playback device is a DVD or a CD based on the determination data (step ST101).
When the disc type discrimination result is DVD (step ST101; YES), the servo DSP 101 controls the driving of the PU / motor driving circuit 104 according to the instruction of the control microcomputer 103, and the objective lens of the optical pickup 100 is in the focus direction. The focus servo pull-in is performed by driving along (step ST102).
In this process, the control microcomputer 103 uses the focus error signal obtained when the objective lens is driven to adjust the input port configuration, gain, offset, etc. of the servo DSP 101 to a mode suitable for DVD playback. Is also included.
When the focus servo pull-in process is completed, the control microcomputer 103 performs a tracking servo pull-in process, and further reproduces and starts the DVD with the servo gain and RF gain settings of the servo DSP 101 set as appropriate for DVD reproduction (step ST103). .

On the other hand, when the disc type discrimination result is CD (step ST101; NO), the control microcomputer 103 uses a focus error signal obtained when the objective lens is driven, and the input port configuration, gain, offset, etc. of the servo DSP 101. To a mode suitable for CD playback. Then, the servo DSP 101 controls the driving of the PU / motor driving circuit 104 according to the instruction of the control microcomputer 103, and drives the objective lens of the optical pickup 100 along the focusing direction to perform the focus servo pull-in (step ST104). ). When this focus servo pull-in process is completed, the control microcomputer 103 performs a tracking servo pull-in process, and further starts and plays back the CD with the servo gain, RF gain setting, etc. of the servo DSP 101 set as appropriate for CD playback (step ST105). ).

FIG. 3 is a diagram showing the relationship between the focus drive signal and the focus error signal in the conventional focus servo pull-in operation. Here, FIGS. 3A and 3B respectively show temporal changes of the focus drive signal and the focus error signal in step ST102 and step ST104 of FIG. The focus drive signal is a drive signal for driving the objective lens by the focus actuator of the optical pickup 100, and is output from the PU / motor drive circuit 104.

3A and 3B, the voltage level A is a set value (focus actuator drive voltage) of a drive amount (launch amount) for driving the objective lens up to the upper limit of the objective lens launch. The objective lens launch upper limit is an upper limit position for driving the objective lens toward the recording surface of the disk d in the focus servo pull-in operation. The voltage level B is a set value (focus actuator drive voltage) of a drive amount (down amount) for driving the objective lens to the lower limit of the objective lens down.
The objective lens lowering lower limit is a lower limit position for driving the objective lens in a direction away from the recording surface of the disk d in the focus servo pull-in operation.
The voltage level C is a servo reference voltage, and is a set value (focus actuator driving voltage) at which the objective lens becomes the servo reference position. The voltage level D is a focus actuator driving voltage at which the objective lens is focused on the pit surface of the DVD, and the voltage level E is a focus actuator driving voltage at which the objective lens is focused on the pit surface of the CD.

It is assumed that the polarity of the focus error signal of the optical pickup 100 changes from positive to negative as the objective lens approaches the disk d.
In addition, the voltage levels D and E always satisfy D <E due to the difference in physical structure and optical specifications between DVD and CD.
Furthermore, in DVDs, the optical pickup 100 is often designed so that the servo reference position at voltage level C is the same as the position at which the objective lens at voltage level D is focused on the pit surface of the DVD. Follow that example.

Next, the focus servo pull-in operation for the DVD in step ST102 will be described in detail with reference to FIG.
The focus servo pull-in operation is started at time t0, and the objective lens is launched from the position of voltage level C to the position of voltage level A between times t0 and t1.
If the objective lens is lowered from the position of voltage level A to the position of voltage level B between times t1 and t2, the objective lens moves away from the disk d. At this time, since the objective lens passes the position of the voltage level D while being away from the disk d, a focus error signal whose polarity changes from minus to plus appears. This focus error signal is used to optimally adjust the input gain and offset of the servo DSP 101 according to the amplitude and balance of the signal input to the servo DSP 101.
At time t2, the objective lens is at the farthest position from the disk d, and the output that the optical pickup 100 receives from the pit surface of the disk d or the reflection from the surface thereof is zero. For this reason, an operation for calculating an offset correction level of an AD converter (not shown in FIG. 1) connected to the input port of the servo DSP 101 is also performed.

Subsequently, when the objective lens is launched from the position of the voltage level B to the position of the voltage level A between times t2 and t3, the objective lens approaches the disk d. At this time, since it passes through the position of the voltage level D while approaching the disk d, a focus error signal whose polarity changes from positive to negative appears. This focus error signal is used to calculate the voltage level (focus pull start level) of the focus error signal that starts the operation of closing the servo loop when the servo DSP 101 performs focus servo pull.

Next, when the objective lens is lowered from the voltage level A position to the voltage level B position between times t3 and t4, the objective lens moves away from the disk d.
Subsequently, when the objective lens starts to be launched from the voltage level B position to the voltage level A position at time t4, the objective lens approaches the disk d.
Thereafter, when the focus error signal reaches the focus pull start level and the objective lens reaches the position of the voltage level D, the servo loop is closed and the focus servo is operated, and the focus servo pull is completed (time t5). ).
Since the disk d may have surface runout, the launch speed of the objective lens starting at time t4 is slower than the launch speed in launching the objective lens starting at time t0 or time t2. This is because, when the disk d has a surface shake, a position change due to a surface shake occurs in addition to a position change due to the launch of the objective lens, and the relative speed of the objective lens with respect to the disk d increases, thereby causing the focus servo pull-in. This is to prevent the performance from significantly deteriorating.
As described above, the time required for the focus servo pull-in operation with respect to the DVD is between the times t0 and t5, that is, the time Tdvd shown in FIG.

Next, the focus servo pull-in operation for the CD in step ST104 will be described in detail with reference to FIG.
The focus servo pull-in operation starts at time t0, and the objective lens is launched from the position of voltage level C to the position of voltage level A between times t0 and t1.
Next, when the objective lens is lowered from the position of voltage level A to the position of voltage level B between times t1 and t2, the objective lens moves away from the disk d.
At this time, since it passes through the position of the voltage level E while moving away from the disk d, a focus error signal whose polarity changes from minus to plus appears. This focus error signal is used to optimally adjust the input gain and offset of the servo DSP 101 according to the amplitude and balance of the signal input to the servo DSP 101.
At time t2, the objective lens is at the farthest position from the disk d, and the output that the optical pickup 100 receives from the pit surface of the disk d or the reflection from the surface thereof is zero. For this reason, an operation for calculating the offset correction level of the AD converter connected to the input port of the servo DSP 101 is also performed.

Subsequently, when the objective lens is launched from the position of the voltage level B to the position of the voltage level A between times t2 and t3, the objective lens approaches the disk d.
At this time, since it passes through the position of the voltage level E while approaching the disk d, a focus error signal whose polarity changes from positive to negative appears. This focus error signal is used to calculate the voltage level (focus pull start level) of the focus error signal that starts the operation of closing the servo loop when the servo DSP 101 performs focus servo pull.

Next, when the objective lens is lowered from the voltage level A position to the voltage level B position between times t3 and t4, the objective lens moves away from the disk d.
Subsequently, when the objective lens starts to be launched from the voltage level B position to the voltage level A position at time t4, the objective lens approaches the disk d.
Thereafter, when the focus error signal reaches the focus pull start level and the objective lens reaches the position of the voltage level E, the servo loop is closed and the focus servo is operated, and the focus servo pull is completed (time t5). ).
Since the disk d may have surface runout, the launch speed of the objective lens starting at time t4 is slower than the launch speed in launching the objective lens starting at time t0 or time t2. The reason for this is the same as that described with reference to FIG.
As described above, the time required for the focus servo pull-in operation with respect to the CD is between the times t0 and t5, that is, the time Tcd shown in FIG.

As is clear from FIGS. 3A and 3B, the focus drive signals in step ST102 and step ST104 are different in focus error because the drive voltage of the focus actuator that focuses on the pit surface is different between DVD and CD. The time at which the signal appears is also different.
However, conventionally, the amount of launching or lowering (driving amount) and the speed of launching or lowering (driving speed) are the same set values for DVD and CD.
In general, a CD tends to have more surface wobbling than a DVD, so that the launch speed of the objective lens starting at time t4 can perform focus servo pull-in with a sufficient margin with respect to the CD. Must be set slow enough.

As described above, in the conventional disk reproducing apparatus, the driving amount and driving speed of the objective lens in the focus servo pull-in are set to be constant regardless of the disk type. For this reason, it is difficult to shorten the startup time. Further, since the driving height of the objective lens is set to be constant regardless of the disc type, there is a problem that the objective lens and the disc d are likely to come into contact with each other.

Therefore, in the disc reproducing apparatus according to the present invention, the focus servo pull-in is performed by setting the launch amount (drive amount) and launch speed (drive speed) of the objective lens according to the disc type of the disc d. With this configuration, the time required for the focus servo pull-in operation can be shortened according to the disc type.
In addition, since an appropriate objective lens driving height is set according to the disc type, the possibility that the objective lens and the disc d come into contact with each other can be reduced. Hereinafter, a disc reproducing apparatus according to Embodiment 1 of the present invention will be described.

FIG. 4 is a block diagram showing the configuration of the disk reproducing apparatus according to Embodiment 1 of the present invention. 4, the disk reproducing apparatus according to Embodiment 1 includes an optical pickup (PU) 1, a servo DSP 2, a DVD / CD reproducing circuit 3, a control microcomputer 4, a PU / motor driving circuit 5, a disk motor 6, and a focus driving. A setting unit 7 is provided.
The optical pickup 1 condenses the light beam on the recording (pit) surface of the disk d with the objective lens, and receives the reflected light component of the light beam as an information signal.
Although not shown in FIG. 4, the optical pickup 1 reproduces a CD and a DVD. For example, an optical pickup for reproducing a DVD having a laser diode, an optical element, and a photoelectric conversion circuit suitable for reproducing a DVD, A CD reproducing optical pickup having a suitable laser diode, optical element and photoelectric conversion circuit.
The optical pickup 1 also includes a focus actuator that drives the objective lens in the focus direction, and a tracking actuator that drives the objective lens in the tracking direction.
The information signal read from the disk d by the optical pickup 1 is supplied to the DVD / CD reproduction circuit 3 via the servo DSP 2.

A servo DSP (Digital Signal Processor) 2 is a servo processing unit that performs focus servo pull-in processing and tracking servo pull-in processing of the objective lens. That is, the servo drive output from the servo DSP 2 is amplified by the PU / motor drive circuit 5 and becomes a drive signal for driving the two actuators of the optical pickup 1 and the disk motor 6 for rotating the disk d. Thereby, the disk d rotates, the objective lens of the optical pickup 1 moves in the focus direction, the focus servo pull-in process is executed, and the objective lens moves in the tracking direction, and the tracking servo pull-in process is executed.
The control microcomputer 4 is a control unit that controls the operation of the servo DSP 2.

The present invention includes a focus drive setting unit 7 that holds the launch amount (drive amount) and launch speed (drive speed) of the objective lens in the focus servo pull-in operation optimized for each disc type. Then, the control microcomputer 4 discriminates the disc type of the disc d to be reproduced, sets the driving amount and driving speed of the objective lens corresponding to the disc type of the discriminated result in the servo DSP 2, and according to the disc type of the disc d. The servo DSP 2 is caused to perform the focus servo pull-in.

Next, the operation will be described.
FIG. 5 is a flowchart showing the operation of the disc reproducing apparatus according to the first embodiment.
First, when the disk d is inserted into the disk reproducing apparatus and the reproduction start of the disk d is started, the control microcomputer 4 instructs the servo DSP 2 to connect the optical pickup 1 and the disk motor 6 to the PU / motor driving circuit 5. Drive with.
Next, the servo DSP 2 processes the signal output from the optical pickup 1 to generate disc type determination data. The control microcomputer 4 acquires the discrimination data generated by the servo DSP 2 (step ST1).
The discriminating data is data corresponding to the disc type generated based on the reflected light component of the light beam received by the optical pickup 1 from the disc d. For example, it is generated from the reflected light component received by the optical pickup 1. Such as the amplitude of the focus error signal, tracking error signal and total light quantity sum signal.

Based on the determination data, the control microcomputer 4 determines whether the disk d inserted into the disk playback device is a DVD or a CD (step ST2).
When the disc type determination result is DVD (step ST2; YES), the control microcomputer 4 instructs the focus drive setting unit 7 to drive the objective lens drive amount (launch height) and drive speed (launch speed). Then, a value optimized for the DVD focus servo pull-in operation is set in the servo DSP 2 (step ST3).

Thereafter, the servo DSP 2 controls the drive of the PU / motor drive circuit 5 based on the value set by the focus drive setting unit 7 to drive the objective lens of the optical pickup 1 along the focus direction. Focus pull-in is performed (step ST4).
In this process, the control microcomputer 4 uses the focus error signal obtained when the objective lens is driven to adjust the input port configuration, gain, offset, etc. of the servo DSP 2 to a mode suitable for DVD playback. Is also included.
When the focus servo pull-in process is completed, the control microcomputer 4 performs a tracking servo pull-in process, and further reproduces and starts the DVD with the servo gain and RF gain settings of the servo DSP 2 set as suitable for DVD reproduction (step ST5). ).

On the other hand, when the disc type determination result is CD (step ST2; NO), the control microcomputer 4 instructs the focus drive setting unit 7 to drive the objective lens drive amount (launch height) and drive speed (launch speed). ), A value optimized for the CD focus servo pull-in operation is set in the servo DSP 2 (step ST6).
Thereafter, the servo DSP 2 controls the drive of the PU / motor drive circuit 5 based on the value set by the focus drive setting unit 7 to drive the objective lens of the optical pickup 1 along the focus direction. Focus pull-in is performed (step ST7).
When this focus servo pull-in process is completed, the control microcomputer 4 performs a tracking servo pull-in process, and further starts playback of the CD with the servo gain, RF gain setting, etc. of the servo DSP 2 set as appropriate for CD playback (step). ST8).

FIG. 6 is a diagram illustrating a relationship between the focus drive signal and the focus error signal in the focus servo pull-in operation according to the first embodiment. FIGS. 6A and 6B show temporal changes of the focus drive signal and the focus error signal, respectively, in the focus servo pull-in operation in step ST4 and step ST7 in FIG.
The focus drive signal is a drive signal for driving the objective lens by the focus actuator of the optical pickup 1 and is output from the PU / motor drive circuit 5.

In FIGS. 6A and 6B, voltage levels A to E are defined in the same way as in FIG. In the present invention, the voltage level A2 and the voltage level B2 are provided in the focus drive signal.
The voltage level A2 is a set value (focus actuator drive voltage) of a drive amount (launch amount) for driving the objective lens to a predetermined launch position in the DVD focus servo pull-in. The predetermined launch position is a position farther from the disk d than the upper limit of the objective lens launch in the conventional DVD focus pull-in. That is, the driving amount of the objective lens at the voltage level A2 is smaller than that at the voltage level A.
The voltage level B2 is a set value (focus / actuator drive voltage) of a drive amount (down amount) for driving the objective lens to a predetermined down position in the CD focus servo pull-in. The predetermined lowering position is a position closer to the disk d than the lower limit of the objective lens lowering in the conventional CD focus pull-in. That is, the driving amount of the objective lens at the voltage level B2 is smaller than that at the voltage level B.

Next, the focus servo pull-in operation for the DVD in step ST4 will be described in detail with reference to FIG.
The focus servo pull-in operation is started at time t0, and the objective lens is launched from the position of voltage level C to the position of voltage level A2 between times t0 and t1 ′.
The voltage level A2 is set to the servo DSP 2 in step ST3, and can be set to a voltage lower than the voltage level A by utilizing the fact that the voltage level D is lower than the voltage level E. Thus, the objective lens reaches the position of the voltage level A2 at time t1 ′ earlier than the conventional time t1 shown in FIG.

If the objective lens is lowered from the position of the voltage level A2 to the position of the voltage level B between times t1 ′ and t2 ′, the objective lens moves away from the disk d. Note that time t2 ′ is earlier than the conventional time t2 shown in FIG.
In this lowering operation, the objective lens passes through the position of the voltage level D, which is the focal point of the DVD, while being away from the disk d, so that a focus error signal whose polarity changes from minus to plus appears. This focus error signal is used to optimally adjust the input gain and offset of the servo DSP 2 in accordance with the amplitude and balance of the signal input to the servo DSP 2.
At time t2 ′, the objective lens is at the farthest position from the disk d, and the output that the optical pickup 1 receives from the pit surface of the disk d or the reflection from the surface thereof is zero. For this reason, an operation for calculating an offset correction level of an AD converter (not shown in FIG. 4) connected to the input port of the servo DSP 2 is also performed.

Subsequently, when the objective lens is launched from the position of the voltage level B to the position of the voltage level A2 between times t2 ′ and t3 ′, the objective lens approaches the disk d. Note that time t3 ′ is earlier than the conventional time t3 shown in FIG.
At this time, since it passes through the position of the voltage level D that is the focal point of the DVD while approaching the disk d, a focus error signal whose polarity changes from positive to negative appears. This focus error signal is used to calculate the voltage level (focus pull start level) of the focus error signal that starts the operation of closing the servo loop when the servo DSP 2 performs focus servo pull.

Next, if the objective lens is lowered from the position of the voltage level A2 to the position of the voltage level B between times t3 ′ and t4 ′, the objective lens moves away from the disk d. Note that time t4 ′ is earlier than the conventional time t4 shown in FIG.
Subsequently, when the objective lens starts to be launched from the position of the voltage level B toward the position of the voltage level A2 at time t4 ′, the objective lens approaches the disk d.
Thereafter, when the focus error signal reaches the focus pull start level and the objective lens reaches the position of the voltage level D, the servo loop is closed and the focus servo is operated, and the focus servo pull is completed (time t5). ').

It should be noted that the launch speed of the objective lens starting at time t4 ′ needs to be slower than the launch speed in launching the objective lens starting at time t0 or time t2 ′ in consideration of surface deflection of the disk d. The reason is the same as in the case where the conventional focus pull-in operation is described with reference to FIGS. 3 (a) and 3 (b).
However, the tendency of the surface shake varies depending on the disc type, and generally the DVD has a smaller amount of surface shake than the CD. For this reason, a DVD can be launched at a faster speed than a CD focus servo pull-in.
The launch speed at the time of the focus servo pull-in is set in step ST3 and step ST6 according to the disc type discrimination result. That is, the focus drive setting unit 7 holds values optimized for each disc type. For example, the launch speed at the time of DVD focus servo pull-in is 9.4 (mm / sec), and the launch speed at the time of CD focus servo pull-in is 2.4 (mm / sec).

In this way, the time required for the DVD focus servo pull-in operation is between the times t0 and t5 ′, that is, the time Tdvd2 shown in FIG.
This time Tdvd2 is obtained by setting the launch voltage level of the objective lens to A2, which is lower than A, and by setting the launch speed at the time of focus servo pull-in to a value faster than that at the time of CD focus servo pull-in. Compared with Tdvd, it is significantly shortened. For example, a time reduction of 1000 to several hundreds (msec) is possible.
Further, the launch height of the objective lens is set at a position of voltage level A2 that is further from the disk d than the position of voltage level A. For this reason, when the objective lens is launched, there is also an effect of reducing the probability of occurrence of a situation in which the objective lens comes into contact with the disk d and scratches are attached to the disk d.

Next, the focus servo pull-in operation for the CD in step ST7 will be described in detail with reference to FIG.
The focus servo pull-in operation is started at time t0, and the objective lens is launched from the position of voltage level C to the position of voltage level A between times t0 and t1. Thereafter, the operation until the objective lens is raised to the position of the voltage level A at time t3 is the same as that in FIG.
If the objective lens is lowered from the position of voltage level A to the position of voltage level B2 between times t3 and t4 ″, the objective lens moves away from the disk d.
The voltage level B2 is a value set from the focus drive setting unit 7 to the servo DSP 2 in step ST6. Using the fact that the position of the voltage level E is higher than the position of the voltage level D (position close to the disk d), a position higher than the position of the voltage level B (position close to the disk d) is set. As a result, the objective lens reaches the position of the voltage level B2 at time t4 ″ earlier than the conventional time t4 shown in FIG.
Thereafter, when the focus error signal reaches the focus pull start level and the objective lens reaches the position of the voltage level E, the servo loop is closed and the focus servo is operated, and the focus servo pull is completed (time t5). ").

As described above, the time required for the CD focus servo pull-in operation is between the times t0 and t5 ″, that is, the time Tcd2 shown in FIG. 6B.
The time Tcd2 can be shortened to 100 to several tens of milliseconds as compared with the conventional Tcd by setting the voltage drop level of the objective lens to B2 higher than B.

As described above, according to the first embodiment, the driving amount and the driving speed of the objective lens in the focus servo pull-in optimized for each disk type are held, and according to the disk type of the disk d to be reproduced. A focus drive setting unit 7 is provided to set the drive amount and drive speed of the objective lens in the servo DSP 2. The servo DSP 2 drives the objective lens according to the disc type determined by the control microcomputer 4 from the focus drive setting unit 7. The amount and driving speed are set, and focus servo pull-in is performed with the driving amount and driving speed of the objective lens according to the disc type of the disc d to be reproduced.
With this configuration, it is possible to reduce the time required for focus servo pull-in according to the type of the disk d.
For example, during DVD playback, the working distance of the objective lens (working distance) is shorter and the surface deflection of the disk is smaller than during CD playback. Focusing on this, focus drive is performed by optimizing the DVD with a value obtained by increasing the drive speed of the objective lens in the focus servo pull-in operation of the DVD and reducing the drive amount (launch amount) of the objective lens. Set in the setting unit 7. As a result, the time from the start to the end of the focus servo pull-in is shortened, and the time required for DVD playback activation is also shortened.
Further, a value obtained by reducing the drive amount (down amount) of the objective lens in the CD focus servo pull-in operation is set in the focus drive setting unit 7 as a value optimized for the CD. In this way, the time required for starting playback of the CD can also be shortened.
Further, in the case of DVD, the probability that the objective lens comes into contact with the disk d can be reduced by reducing the driving amount (launch amount) of the objective lens. Thereby, the probability of occurrence of scratches on the disk d can be reduced.

In the first embodiment, the position of the voltage level A2, which is the launch height of the objective lens, has been shown to be set alternatively with the position of the voltage level A according to the disc type. It is not limited to. For example, when launching from the position of voltage level B to the position closest to the disk d, the launch height is adaptively set according to the focus actuator drive voltage for which the focus error signal is measured, and the objective lens launch upper limit for DVD is set. You may control to optimize.

Embodiment 2. FIG.
In the first embodiment, the case where the launch amount and launch speed of the objective lens at the time of focus servo pull-in previously held in the focus drive setting unit 7 is set uniformly according to the disc type has been shown. On the other hand, in the second embodiment, a mode in which the launch amount and launch speed of the objective lens at the time of focus servo pull-in is adaptively set according to the surface shake amount of the disk d will be described. The configuration of the disc playback apparatus according to the second embodiment is the same as that shown in FIG.

FIG. 7 is a diagram showing a relationship between the focus drive signal and the focus error signal in the focus servo pull-in operation according to the second embodiment of the present invention. (I) and (ii) in FIG. 7 are simplified representations of temporal changes in the focus drive signal and the focus error signal when the CD focus servo is pulled in. The voltage levels A, B, and E are the same as those described in FIG. 3 of the first embodiment.

When the disk d is in an ideal state with no runout, when the objective lens is launched from the position of the voltage level B to the voltage level A from time t2 to time t3, it is indicated by a solid line portion in (ii) of FIG. Thus, the focus error signal (S-curve) appears only when passing through the position of the voltage level E.

On the other hand, when the disk d has surface runout, in FIG. 7 (ii), many S-shaped curves appear as shown by dotted lines in addition to the solid line portions. This is because the distance between the objective lens and the disk d periodically changes due to surface fluctuations, and thus the position of the voltage level E passes a plurality of times even when the driving voltage of the objective lens rises at a constant speed. To do.

Therefore, in the second embodiment, the control microcomputer 4 measures the number of appearances of the S-shaped curve and compares the measured number of appearances with a threshold value, thereby determining the magnitude of the surface shake of the disk d.
For example, if the number of appearances is 3 or less, the surface shake is small, and if it is 4 or more, the surface shake is determined to be large.

When it is determined that the surface runout is large, the servo DSP 2 performs the launch speed (drive speed) set by the focus drive setting unit 7 as shown in the dotted line in FIG. ) At time t4. As a result, the servo loop is closed at time t5, the focus servo operates, and the focus pull-in is completed.
On the other hand, if it is determined that the surface runout is small, the servo DSP 2 is faster than the launch speed (drive speed) set by the focus drive setting unit 7 as shown by the solid line in FIG. The launch is performed from time t4. Thereby, the servo loop is closed at time t5a, the focus servo operates, and the focus pull-in is completed. Since time t5a <time t5, the time until the focus servo pull-in is completed is shortened.

As described above, according to the second embodiment, the control microcomputer 4 inputs the focus error signal that appears when the objective lens is driven, and the reproduction of the disk d to be reproduced is based on the temporal change of the focus error signal. When the magnitude of the surface shake is determined and the servo DSP 2 determines that the surface shake of the disk d is small, the drive speed of the objective lens in the focus servo pull-in is higher than the speed set by the focus drive setting unit 7. Make it faster.
In this way, the time required for focus servo pull-in can be shortened.

In the first and second embodiments, the objective lens dropping speed from time t1 ′ (t1) to time t2 ′ (t2) and time t2 ′ (t2) in FIGS. 6 (a) and 6 (b). ) To t3 ′ (t3) in which the launch speed of the objective lens is constant regardless of the disc type of the disc to be reproduced, but as in the second embodiment, the magnitude of the surface deflection of the disc d is large or small. It may be changed adaptively according to the above. For example, if the surface fluctuation of the disk d is small, the speed of the period is set fast.

In the first and second embodiments, the focus drive setting unit 7 is a separate component from the servo DSP 2, but this may be configured as a part of the servo DSP 2.

Further, the present invention is not limited to a disc playback device that plays back DVDs and CDs, and may be applied to, for example, a BD / DVD / CD disc playback device that can play back Blu-ray Discs (BD). Is possible.

In the present invention, within the scope of the invention, any combination of each embodiment, any component of each embodiment can be modified, or any component can be omitted in each embodiment. .

The disc reproducing apparatus according to the present invention can shorten the time required for the focus servo pull-in operation according to the disc type, and is suitable for, for example, an in-vehicle disc reproducing device in which various types of discs are used. It is.

1. Optical pickup, 2. Servo DSP, 3. DVD / CD playback circuit, 4. Control microcomputer, 5. PU / motor drive circuit, 6. Disk motor.

Claims

An optical pickup that focuses the light beam on the recording surface of the disc with an objective lens;
The objective lens is moved to a position where the objective lens is focused on the recording surface of the disc, and focus servo pull-in is performed to operate a focus servo. Based on the reflected light component of the light beam received from the disc by the optical pickup, A servo processing unit that generates data for determination used for determination;
In a disc playback apparatus comprising a control unit that discriminates a disc type using the discrimination data,
The servo processing unit holds the driving amount and driving speed of the objective lens in the focus servo pull-in optimized for each disc type, and sets the driving amount and driving speed of the objective lens according to the disc type of the disc to be reproduced. Focus drive setting unit to set to
The servo processing unit sets the driving amount and driving speed of the objective lens according to the disc type determined by the control unit from the focus drive setting unit, and according to the disc type of the disc to be reproduced. A disc reproducing apparatus, wherein the focus servo is pulled in by a driving amount and a driving speed of the objective lens.
The control unit inputs a focus error signal that appears when the objective lens is driven, determines the magnitude of the surface shake of the disc to be reproduced based on the time change of the focus error signal,
The servo processing unit makes the driving speed of the objective lens in the focus servo pull-in faster than the speed set by the focus driving setting unit when it is determined that the surface deflection of the disk is small. The disk reproducing apparatus according to claim 1.
In the focus servo pull-in method of operating the focus servo by moving the objective lens in the optical pickup to a position where it is focused on the recording surface of the disc,
Generating discriminating data used for disc type discrimination based on the reflected light component of the light beam received from the disc by the optical pickup;
Discriminating the disc type of the disc to be reproduced using the discriminating data;
Step of performing focus servo pull-in with the drive amount and drive speed of the objective lens according to the disc type of the disc to be reproduced among the drive amount and drive speed of the objective lens in the focus servo pull-in optimized for each disc type And a focus servo pull-in method.
Determining the magnitude of the surface shake of the disc to be reproduced based on the temporal change of the focus error signal that appears when the objective lens is driven;
4. The focus servo pull-in method according to claim 3, wherein when it is determined that the surface deflection of the disk is small, the drive speed of the objective lens in the focus servo pull-in is faster than a speed optimized in advance.