WO2007052525A1

WO2007052525A1 - Objective lens drive device and drive method

Info

Publication number: WO2007052525A1
Application number: PCT/JP2006/321354
Authority: WO
Inventors: Yoshimichi Nishio; Takaaki Ujiie; Yoshihiro Hashizuka
Original assignee: Pioneer Corporation
Priority date: 2005-11-07
Filing date: 2006-10-26
Publication date: 2007-05-10
Also published as: JPWO2007052525A1; JP4660555B2

Abstract

[PROBLEMS] To modify drive speed of a objective lens according to an optical disc wobbling amount in an objective lens drive device provided in an optical disc device and reduce a focus pull-in time when wobbling is small. [MEANS FOR SOLVING PROBLEMS] An objective lens in an optical pickup (3) is moved within a certain range from a servo signal processing unit (5). A focus error signal generated when the objective lens crosses a focal point on an optical disc (11) is observed by the servo signal processing unit (5). According to the observation result, a microcomputer (10) modifies the speed of movement of the objective lens for performing focus pull-in.

Description

Specification

Objective lens driving apparatus and driving method

Technical field

[0001] The present invention relates to a driving apparatus and a driving method for driving an objective lens used in an optical disk reproducing apparatus or the like.

Background art

[0002] Optical disc playback devices and the like require an operation to focus the objective lens on the signal surface of the optical disc (focus pull-in) before playback of the optical disc. Changes in the operating environment of the playback device, warping of optical discs and signals In consideration of changes in the relative speed between the optical disc and the objective lens due to surface deflection caused by surface distortion, etc., the drive speed of the objective lens is fixed at a constant speed so that the focus bow I can be inserted even under the worst conditions. And then.

[0003] However, in this case, the change in the relative speed between the optical disk and the objective lens is small, that is, the surface blurring is small! / In the optical disk, the objective lens is driven at a speed that matches the worst condition! / It took unnecessary time to pull the focus. In order to solve this, there is proposed a method described in Patent Document 1 for changing the driving speed of the objective lens at the time of focus pull-in.

Patent Document 1: Japanese Patent Application Laid-Open No. 2004-14091

Disclosure of the invention

Problems to be solved by the invention

[0004] In the method described in Patent Document 1, the force to measure the focus error signal at any part of the surface blur when the optical disk to be played back is measured, that is, when the signal surface of the optical disk approaches the objective lens due to the surface blur. Because the relative speed changes depending on whether the measurement is performed when moving or leaving, there is a problem that the driving speed may be different from the speed that should be driven. As a result, the time required for focus pull-in is increased.

[0005] Therefore, according to the present invention, for example, even when an optical disc to be reproduced has surface blur, the amount of surface blur is It is an object of the present invention to provide an objective lens driving device and a driving method capable of shortening the force pull-in time when there is little blurring by setting the driving speed of the objective lens according to the above.

Means for solving the problem

[0006] In order to solve the above problems, the invention according to claim 1 is directed to a light source, an objective lens for irradiating light from the light source with focusing on the optical disc, and the objective lens to the optical disc. On the other hand, in an objective lens driving device comprising a driving means for moving in a substantially vertical direction, the observation means is caused to observe the focal point on the optical disc by moving the objective lens to a certain range by the driving means. And a control means for changing the speed at which the driving means moves the objective lens in order to perform the force pull-in according to the result! / Speak.

[0007] The invention according to claim 9 is directed to an objective lens driving method for moving an objective lens for irradiating light of light source power while focusing on the optical disc in a substantially vertical direction with respect to the optical disc. The objective lens is moved by a certain amount, the focal point on the optical disc is observed, and the speed at which the objective lens is driven is changed according to the observation result in order to perform focus pull-in.

Brief Description of Drawings

[0008] FIG. 1 is a block diagram of an optical disc player according to a first embodiment, a second embodiment, and a third embodiment of the present invention.

2 is an explanatory diagram of a light receiver of the optical pickup in the optical disc player shown in FIG.

FIG. 3 is an explanatory diagram of a waveform of a focus error signal.

4 is a flowchart showing an objective lens driving speed determining operation in the first embodiment of the optical disc player shown in FIG. 1. FIG.

[FIG. 5] (a), (b) and (c) are explanatory diagrams of the relationship between the objective lens when the objective lens is driven, the focal point of the light emitted from the objective lens, and the signal surface of the optical disc.

6 is a flowchart showing an objective lens drive speed determination operation in the second embodiment of the optical disc player shown in FIG. 1. FIG. FIGS. 7A and 7B are explanatory diagrams of a method for determining the driving speed of the objective lens in the second embodiment.

8 is a flowchart showing an objective lens driving speed determination operation in the third embodiment of the optical disk player shown in FIG. 1. FIG.

FIG. 9 is an explanatory diagram of a method for determining a driving speed and a driving range of an objective lens according to a third embodiment.

Explanation of symbols

[0009] 1 Optical disc player (objective lens driving device)

3 Optical pickup (light source, objective lens)

5 Servo signal processor (drive means, observation means)

10 Microcomputer (Control means, position acquisition means)

11 Optical disc

S102 Focus error signal observation, observation count and time interval measurement (observation method)

S103 Time interval judgment

S104 Level difference judgment

S108 Jitter amount judgment

S202 Focus error signal observation and time width measurement (observation means)

S203 Level difference judgment

S206 Surface shake amount judgment

S302 Focus error signal observation and observation position measurement (observation means, position detection means) S303 Level difference judgment

S306 Surface runout judgment

S309 Drive range lower limit setting

S310 Drive range upper limit setting

BEST MODE FOR CARRYING OUT THE INVENTION

[0010] Hereinafter, an objective lens driving device that works according to an embodiment of the present invention will be described. An objective lens driving device according to an embodiment of the present invention moves an objective lens to a driving means within a certain range. And a control means for causing the observation means to observe the focal point on the optical disc and changing the moving speed of the objective lens in order to perform the focus pull-in according to the observation result. By doing this, it is possible to grasp the state of optical disc surface blurring by observing the focal point on the optical disc, so that focus pull-in can be performed at a speed that matches the amount of surface blurring. If there is little, the focus pull-in time can be shortened.

[0011] Further, as a result of observation by the observation means, the control means increases the speed at which the objective lens is driven when the number of times of crossing the focal point on the optical disk is less than a predetermined value. When there are many, the speed which drives an objective lens may be made slow. That is, when the surface blur is large, the number of times of crossing the focal point is large. When the surface blur is small, the number of times of crossing the focal point is small. Therefore, the driving speed of the objective lens can be changed depending on the amount of surface blur.

[0012] In addition, when the observation means observes that the time width until the force finally crosses the focal point on the optical disc is shorter than a predetermined first predetermined time, the objective The speed for driving the lens may be increased, and the speed for driving the objective lens may be decreased when longer than the first predetermined time. In other words, when the surface blur is large, the time width until the force crosses the focal point first is long.When the surface blur is small, the time width until the force crosses the focal point first is short. Therefore, the driving speed of the objective lens can be changed depending on the amount of surface blur.

[0013] Further, the control means causes the position acquisition means to acquire the position of the objective lens when the observation means observes the focal point on the optical disc, and first adjusts the objective lens when the objective lens is moved within a certain range. Depending on the position where the focal point was observed and the position where the focal point was last observed, the driving range for focusing the objective lens may be changed. By doing so, the range in which the objective lens is driven can be limited, so that the focus pull-in time can be shortened.

[0014] Further, the control unit divides the fixed range in which the objective lens is moved into a plurality of ranges, and moves the driving range of the objective lens at the time of focus pull-in according to the range where the focal point exists in the plurality of ranges. You may do it. By doing this, the focus pull-in time can be shortened because the range where the in-focus point exists can be limited during focus pull-in. It can be done.

[0015] In addition, when a plurality of focal points on the optical disc observed by the observation unit are observed within a predetermined second predetermined time, the control unit performs a plurality of the above observations observed within the second predetermined time. The focal point may be counted as one. As a result of such rubbing, it is possible to accurately measure the amount of surface blur in an optical disk in which a plurality of layers are laminated.

[0016] Further, the control means may target only the in-focus in which the intensity of the reflected light of the optical disc is within a predetermined range among the plurality of in-focus on the optical disk observed by the observation means. In this way, the amount of surface blur can be accurately measured even on an optical disc in which a plurality of media (such as BD and DVD) are stacked.

[0017] In addition, the observation unit may set a position where any one or more of the focus error signal, the RF signal, and the return light total signal are observed as a focal point. These signals are signals that are generated when the amount of reflected light from the optical disc exceeds a predetermined amount, so that it is easy to observe the focal point.

[0018] Further, in the objective lens driving method according to one embodiment of the present invention, the focal point on the optical disc is observed by moving the objective lens by a certain amount, and the focus is pulled in according to the observation result. The speed at which the objective lens is driven is changed. In this way, the state of optical disc surface blur can be ascertained by observing the focal point on the optical disc, so that focus pull-in can be carried out at a speed that matches the amount of surface blur. In this case, the focus pull-in time can be shortened.

[0019] Also, the position of the objective lens when the focal point on the optical disk is observed is acquired, and the focal point is first observed when the objective lens is moved within a certain range, and finally the focal point is determined. The driving range for focusing the objective lens may be changed according to the observed position. By doing so, the range in which the objective lens is driven can be limited, so that the focus pull-in time can be shortened.

Example 1

[0020] An optical disc player 1 as an objective lens driving device that is effective in the first embodiment of the present invention will be described with reference to Figs. The optical disc player 1 has multiple optical discs such as a DVD (Digital Versatile Disc), CD (Compact Disc), and BD (Blu-ray Disc), and multiple DVDs. It is a device that can reproduce multi-layer discs such as laminated optical discs and optical discs with DVD layers and BD layers. As shown in Fig. 1, disc motor 2, optical pickup 3, RF amplifier 4, servo signal A processing unit 5, a driver 6, an audio Z video signal processing unit 7, a DA converter 8, an audio signal Z video signal output terminal 9, and a microcomputer 10 are provided.

[0021] The disc motor 2 is a motor for rotating the optical disc 11 set in the optical disc player 1, and includes a spindle motor or the like.

The optical pickup 3 includes a laser diode (not shown) that generates light to be irradiated on the optical disc 11, an objective lens for irradiating the optical disc 11 with laser light from the laser diode, and a servo signal processing unit 5 And a receiver 30 that receives the reflected light reflected from the optical disk 11, and a focus error signal as a focal point is output from the output of the receiver 30. Generate and output.

As shown in FIG. 2, the light receiver 30 includes a four-divided light receiver 31. The quadrant light receiver 31 includes light receiving surfaces 31a, 31b, 31c and 31d.

[0024] The focus error signal is obtained by adding the outputs of the light receiving surfaces 31b and 31d at the other diagonal position from the sum of the outputs of the light receiving surfaces 3la and 31c at one of the diagonal positions in the quadrant light receiver 31. 3 is subtracted (ie, (31a + 31c)-(31b + 31d)) and the waveform shown in FIG. 3 is obtained, and Vfe in FIG. 3 is the focus error signal level as the intensity of reflected light at the focal point.

The RF amplifier 4 amplifies the signal output from the optical pickup 3 to a predetermined value and outputs it to the servo signal processing unit 5.

[0026] Servo signal processing unit 5 as drive means and observation means is used to observe the presence and level of a focus error signal, which is a signal input from the reflected light from optical disk 11 and input to RF amplifier 4 power, The objective lens of the pickup 3 is driven to control focus and tracking so that the information recorded on the optical disk 11 can be read accurately. Further, a signal including information such as music and video recorded on the optical disc 11 is converted to analog Z digital and output to the audio Z video signal processing unit 7. The driver 6 amplifies the signal input from the servo signal processing unit 5 and outputs the amplified signal to the disk motor 2 and the optical pickup 3.

[0028] The audio Z video signal processing unit 7 demodulates the signal input from the servo signal processing unit 5 into an audio or video signal, performs error correction, and outputs the signal to the DA converter 8.

The DA converter 8 converts the digital signal input from the audio Z video signal processing unit 7 into an analog signal and outputs the analog signal from the audio output terminal 9a and the video output terminal 9b.

[0030] A microcomputer 10 serving as a control means and a position acquisition means has a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory), and the optical disk 11 is inserted and ejected. Controls the entire optical disc player 1 in each operation such as recording Z playback and stop, and determines the objective lens drive speed and drive range from the focus error signal observed by the servo signal processing unit 5.

Next, the operation for determining the drive speed of the objective lens in the optical disc player 1 having the construction force shown in FIG. 1 will be described with reference to the flowchart shown in FIG. The flowchart shown in FIG. 4 is realized by the CPU of the microcomputer 10 executing the control program stored in the ROM of the microcomputer 10.

[0032] Referring to FIG. 5, the relationship between the objective lens, the focal point of the light emitted from the objective lens, and the signal surface of the optical disc when the objective lens is moved in a direction in which the positional force far from the optical disc is brought closer to the optical disc. explain. Fig. 5 (a) shows the case where the optical disc surface is shaken, that is, when the optical disc rotates, the signal plane has a large fluctuation in the focus direction. In Fig. 5 (a), the focal point of the objective lens is separated from the objective lens by a distance h0. If the objective lens moves, the focal point moves while maintaining the distance h0. As shown in Fig. 5, when the objective lens is moved from hi to h2 in the focus direction, the signal surface of the optical disc crosses the focal point (a to i in Fig. 5 (a)). When the surface blur is large, the number of times the signal surface of the optical disk crosses the focal point increases. Figure 5 (b) shows the case where the surface blur is small. When the surface blur is small, even if the objective lens is moved in the same way as when the surface blur is large, the number of times the signal surface of the optical disk crosses the focal point is smaller than when the surface blur is large.

[0033] When the signal surface of the optical disc crosses the focal point, a focus error signal is generated from the reflected light from the optical disc when it crosses. If the number is counted, the number of times of crossing the focal point is counted, and the size of the surface blur can be distinguished by the number of times. The detailed operation of the present embodiment having the above-described contents will be described below with reference to the flowchart of FIG.

First, in step S 101, the servo signal processing unit 5 is instructed to drive the objective lens in the vertical direction with respect to the optical disc 11 while continuing to irradiate the laser light from the laser diode of the optical pickup 3. Proceed to step S102. The servo signal processing unit 5 outputs, via the driver 6, a signal that drives the objective lens away from the optical pickup 3, for example, in the direction toward the optical disc 11 and close to the positional force optical disc 11. The fixed range is a range in which the objective lens is driven while continuing to irradiate laser light from a laser diode sufficient to determine the amount of surface blurring of the optical disc 11 in step S108 described later. For example, the bottom dead center To top dead center.

Next, in step S102 as observation means, the servo signal processing unit 5 observes the focus error signal output from the optical pickup 3 when the signal surface of the optical disc 11 crosses the focal point. When the focus error signal is observed, the observed focus error signal level as the intensity of the reflected light is output to the microcomputer 10.

[0036] In the microcomputer 10, the focus error signal level observed from the servo signal processing unit 5 and input to the microcomputer 10 and the observation time of the focus error signal observed from the first time on the basis of the focus error signal first observed are used. measure. The observation time of the focus error signal and the level at that time are stored in RAM in the microcomputer 10. Further, the result of counting the total number of observed focus error signals as a result of moving the objective lens is also stored in the RAM in the microcomputer 10, and the process proceeds to step S103.

[0037] Next, in step S103, it is determined whether or not a plurality of focus error signals are observed within a second predetermined time set in advance and stored in the ROM of the microcomputer 10 as a result of moving the objective lens. To do. If a plurality of observations are made within the second predetermined time (in the case of YES), the process proceeds to step S107, and if not (in the case of NO), the process proceeds to step S104. When there are multiple signal surfaces of the same media (for example, DVD) with the second predetermined time, the focal point of one signal surface (focus error signal) and the focal point of the other signal surface (four This is a time interval sufficient for observing a cascading error signal). If each focal point of multiple signal planes is counted once, it will be counted more than the actual amount of surface blurring. Therefore, the focus error signal observed within this second predetermined time is counted as one time. As an example, Fig. 5 (c) shows the case where there are two signal surfaces. In the case of two layers, there are two waveforms representing the signal plane that is blurred as shown in Fig. 5 (c). In Fig. 5 (c), the signal plane crosses the focal point in the first and second layers, and there are six locations. Will be misjudged. Therefore, the accurate amount of surface blur can be determined by counting the number of times one signal surface crosses the focal point. The second predetermined time is, for example, twice the time required to move the objective lens by the distance between the two most distant layers among the signal surfaces stacked on the optical disk 11. In general, when multiple media of the same type are stacked on an optical disk, the distance between each layer is very small compared to the surface blur width of the optical disk. Such a judgment is effective for counting the number of times the signal surface of the optical disk crosses the focal point by moving the optical disk.

Next, in step S104, when the focus error signal level first observed is within a range of levels that can be taken in the case of a predetermined type of optical disc stored in the ROM of the microcomputer 10, for example, a DVD. Then, it is determined whether or not all the focus error signal levels observed after the second are within the range of levels that can be taken by the DVD that is a predetermined range stored in the ROM of the microcomputer 10. If all observed focus error signal levels are within the range of levels that can be taken by the DVD (in the case of YES), the process proceeds to step S105, and if a level outside the predetermined range exists (in the case of NO), the step is performed. Proceed to S106. That is, it is determined whether or not the focus error signal level is within a predetermined range. The predetermined range means that when a focus error signal as the focal point is observed from multiple layers on an optical disc 11 in which multiple media (for example, BD and DVD) are stacked, the number of actual surface blurs is counted more than the actual range. Therefore, it refers to the range of levels that the media can take in order to count only the focus error signals from a particular media layer. Generally, since the position of the recording surface (depth from the optical disk surface) on the optical disc is determined for each type of media, different types of media are stacked. In some cases, the distance between layers may be increased depending on the combination of media. On the other hand, when a laser beam corresponding to a specific medium is irradiated onto an optical disk, the range that the focus error signal level can take varies depending on the type of the medium of the optical disk. Therefore, it is effective to use the focus error signal level in order to count only the focus error signal of a specific medium layer force on an optical disc in which different types of media are stacked.

[0039] Next, in step S105, the total number of observations of the focus error signal counted in step S102 is read from the RAM, and the process proceeds to step S108.

[0040] In step S106, an optical disc on which different types of media are stacked (for example, BD and D

VD), and only the signals having a level difference within a predetermined range compared with the focus error signal observed first are counted, and the process proceeds to step S108. That is, only the focus error signal within a predetermined range is counted.

[0041] In step S107, it is determined that the same type of media such as DVDs is stacked, and a plurality of focus error signals observed within the second predetermined time are counted as one time. Then go to step S108. For example, if the second predetermined time is t in Fig. 5 (c), the time from the point j where the signal plane of the first layer crosses the focal point to the point where the signal plane of the second layer crosses the focal point is 5 Because it is within t as shown in (c); Γ is not counted. Similarly, other points where the signal plane of the second layer crosses the focal point in Fig. 5 (c) are not counted because they are within t from the point where the signal plane of the first layer crosses the focal point.

[0042] Next, in step S108, it is determined whether or not the counted number of focus error signals is equal to or greater than a predetermined value that is preset and stored in the ROM of the microcomputer 10. If YES, the process proceeds to step S110. If less than the predetermined value (NO), the process proceeds to step S109. The predetermined value is a value with which the amount of surface blur can be determined.

[0043] Next, in step S109, the number of times the focus error signal has been observed is small, that is, the number of times that the signal surface of the optical disk has crossed the focal point is less than the predetermined value, so it is determined that the surface blur is small! / Then, the servo signal processing unit 5 is instructed to drive the object lens at a speed (high speed) that is faster than the speed at the predetermined worst condition. [0044] Next, in step SI10, if the focus error signal is observed many times, that is, if the signal surface of the optical disc crosses the focal point is more than a predetermined value, The servo signal processing unit 5 is instructed to drive the objective lens at a slow V and speed (low speed) so that the focus can be pulled in even under the worst condition determined in advance.

[0045] According to the present embodiment, the number of times of crossing the signal surface of the optical disk and the focal point is counted, and if the result is equal to or greater than a predetermined value set in advance, it is determined that the surface blur is large and the objective lens is moved at a low speed. Since the objective lens is driven at high speed because it is judged that the surface blur is small if it is less than the predetermined value, the drive speed of the objective lens can be changed according to the amount of surface blur. When the amount is small, the focus pull-in time is shortened.

Example 2

Next, an optical disc player 1 as an objective lens driving device that works in the second embodiment will be described with reference to FIG. 6 and FIG. The same parts as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

[0047] In this embodiment, the configuration is the same as that of the first embodiment. Instead of counting the number of times that the signal surface of the optical disk crosses the focal point in determining the magnitude of the amount of shake on the surface of the optical disk, The difference is that the time span is measured from the time the surface first crosses the focal point to the last time it crosses the focal point. Therefore, a part of the control program of the microcomputer 10 has been changed. FIG. 6 shows a flow of operations for determining the driving speed of the objective lens in the present invention.

[0048] A method for determining the driving speed of the objective lens in the present embodiment will be described with reference to FIG. Figure 7 shows the same distance h0 to the focal point and the amount of surface blur as in Figure 5. Fig. 7 (a) shows the case where the optical disc surface shake is large! /. As shown in Fig. 7 (a), when the objective lens is moved in a certain range up to h2 in the focus direction, the time when the signal surface of the optical disc first crosses the focal point The time when the tl force also crosses last There is a time span of T1 by t2. Figure 7 (b) shows the case where the surface shake is small! /. Time t3 force when the signal surface of the optical disc first crosses the focal point for the first time t3 force time T4 is the time width by t4 when it last crosses. That is, as shown in FIG. 7, when the objective lens is moved, the time width that the signal surface of the optical disc crosses the focal point is smaller when the surface blur is small than when the surface blur is large (T1> T2). Therefore, as in the first embodiment, the focus error signal is observed, It is possible to distinguish the magnitude of the surface shake by measuring the observation result force time width. Hereinafter, the detailed operation in the present embodiment will be described with reference to the flowchart of FIG.

First, in step S 201! /, The servo signal processing unit is configured to drive the objective lens in a vertical direction with respect to the optical disc 11 while continuing to irradiate laser light from the laser diode of the optical pickup 3. Instruct 5 and go to Step S202. The servo signal processing unit 5 outputs, via the driver 6, a signal that drives the objective lens away from the optical pickup 3, for example, away from the optical disk 11 and closer to the positional force optical disk 11. Note that the fixed range is a range in which the objective lens is driven while continuing to irradiate laser light from a laser diode sufficient to determine the amount of surface blur of the optical disc 11 in step S206, which will be described later. For example, the bottom dead center To top dead center.

[0050] Next, in step S202 as observation means, the servo signal processing unit 5 observes the focus error signal output from the optical pickup 3 when the signal surface of the optical disc 11 crosses the focal point. When the focus error signal is observed, the observed focus error signal level as the intensity of the reflected light is output to the microcomputer 10. The microphone computer 10 measures the observed focus error signal level and the time width at which the focus error signal is first observed and the force error signal is finally observed, and stores it in the RAM. Then, the process proceeds to step S203.

[0051] Next, in step S203, the focus error signal level first observed is a range of levels that can be taken in the case of a predetermined type of optical disc stored in the ROM of the microcomputer 10, for example, a DVD. If it is determined that all the focus error signal levels observed after the second are within the range of levels that can be taken by the DVD, which is a predetermined range stored in the ROM of the microcomputer 10. If all the observed focus error signal levels are within the range of levels that can be taken by the DVD (in the case of YES), the process proceeds to step S204. If a level outside the predetermined range exists (in the case of NO), the process proceeds to step S205. Proceed to That is, it is determined whether or not the focus error signal level is within a predetermined range. Note that the predetermined range is the same as in step S104, when the focus error signal as the in-focus point is observed from multiple layers on the optical disc 11 on which a plurality of media (for example, BD and DVD) are stacked. More than counted Therefore, in order to count only the focus error signal from a specific media layer, the range of levels that the media can take! Uh.

[0052] Next, in step S204,! /, Using the time width measured in step S202 as it is, the process proceeds to step S206.

[0053] In step S205, it is determined that the disc is an optical disc (eg, BD and DVD) on which different types of media are stacked, and the level is within a predetermined range compared to the focus error signal first observed. Remeasure the time width of the difference signal only, and go to Step S206. That is, only the focus error signal within a predetermined range is counted.

Next, in step S206, it is determined whether or not the time width of the measured focus error signal is equal to or longer than a first predetermined time set in advance and stored in the ROM of the microcomputer 10. If it is longer than the predetermined time (in the case of YES), the process proceeds to step S208. If it is less than the predetermined time (in the case of NO), the process proceeds to step S207. The first predetermined time is a time width in which the amount of surface shake can be distinguished.

[0055] Next, in step S207, the time width over which the focus error signal is observed is shorter than the first predetermined time, that is, the time width in which the signal surface of the optical disk crosses the focal point is short, so it is determined that the surface blur is small. Then, the servo signal processing unit 5 is instructed to drive the objective lens at a speed (high speed) faster than the speed at the predetermined worst condition.

[0056] Next, in step S208, the time width over which the focus error signal is observed is longer than the first predetermined time, that is, the time width in which the signal surface of the optical disk crosses the focal point is long, so it is determined that the surface blur is large. Then, the servo signal processing unit 5 is instructed to drive the objective lens at a slow speed (low speed) at which the focus can be pulled in even in the worst case condition.

[0057] According to the present embodiment, the time width over which the signal surface of the optical disk crosses the focal point is measured, and if the result is equal to or longer than the first predetermined time set in advance, it is determined that the surface blur is large and the speed is low. When the objective lens is driven, and the objective lens is driven at a high speed because it is judged that the surface blur is small if it is less than the first predetermined time, the driving speed of the objective lens is changed according to the amount of the surface blur. If the surface blur is small, the focus pull-in time is shortened. Example 3 Next, an optical disc player 1 as a reproducing apparatus equipped with an objective lens driving device that is effective in the third embodiment will be described with reference to FIG. 8 and FIG. The same parts as those in the first embodiment and the second embodiment described above are denoted by the same reference numerals and description thereof is omitted.

The configuration of this embodiment is the same as that of the first embodiment, but the focus pull-in is reduced by limiting the drive range that can be achieved by simply changing the drive speed of the objective lens by determining the amount of surface blur. Reduce time. Therefore, a part of the control program of the microcomputer 10 has been changed. Fig. 8 shows the flow of operations for determining the driving speed of the objective lens in the present invention.

In this embodiment, as shown in FIG. 9, when the objective lens is moved in the focus direction to a certain range up to the hi force h2, it is divided into 1 to 10 areas in the time axis direction, and the signal surface of the optical disc is the first. The crossing area and the last crossing area are detected, and the drive speed and drive range are determined according to the number of areas and the area number. Hereinafter, detailed operations in this embodiment will be described with reference to the flowchart of FIG.

First, in step S301, the servo signal processing unit 5 is instructed to drive the objective lens in a vertical range with respect to the optical disc 11 while continuing to irradiate laser light from the laser diode of the optical pickup 3 (step S302). Proceed to The servo signal processing unit 5 outputs, via the driver 6, a signal that drives the objective lens away from the optical pickup 3, for example, away from the optical disk 11 and closer to the positional force optical disk 11. The fixed range is a range in which the objective lens is driven while irradiating laser light from the optical pickup 3 sufficient to determine the amount of surface blur of the optical disk 11 in step S306 described later. Desirably, from point to top dead center.

Next, in step S302 as the observation means and the position acquisition means, the servo signal processing unit 5 converts the focus error signal output from the optical pickup 3 when the signal surface of the optical disk 11 crosses the focal point. When the focus error signal is observed, the observed focus error signal level is output to the microcomputer 10. In the microcomputer 10, when the focus error signal level is inputted from the servo signal processing unit 5, the area number as the observation position and the level as the intensity of the reflected light are combined and stored in the RAM. Furthermore, as a result of moving the objective lens over a certain range, the focus error is Area force where one signal was observed Finally, count the number of areas up to the area where the focus error signal was observed, store it in RAM, and proceed to step S303.

[0063] Next, in step S303, when the first observed focus error signal level is within a range of levels that can be taken in the case of a predetermined type of optical disk, such as a DVD, stored in advance in the ROM of the microcomputer Determines whether all the focus error signal levels observed after the second are within the range of levels that can be taken by the DVD, which is a predetermined range stored in the ROM of the microcomputer 10. If all of the observed focus error signal levels are within the range of levels that the DVD can take (YES), go to step S305. If there is a level outside the specified range (NO), go to step S304. move on. That is, it is determined whether or not the focus error signal level is within a predetermined range. Note that the predetermined range is the same as in steps S104 and S203, when the focus error signal as the focal point is observed from multiple layers on the optical disc 11 on which a plurality of media (for example, BD and DVD) are stacked. Because it counts more than the amount, the range of levels that the media can take to count only the focus error signals from a particular media layer! Uh.

[0064] Next, in step S304, the number of areas counted in step S302 is read from the RAM, and the process proceeds to step S306.

[0065] In step S305, it is determined that the disc is an optical disc on which different types of media are stacked (for example, BD and DVD), and all levels and areas in which the RAM force is also observed are read out and observed first. The number of areas in which a signal with a level difference within a predetermined range is observed compared with the focus error signal is counted, and the process proceeds to step S306. That is, only the focus error signal within a predetermined range is counted.

[0066] Next, in step S306, it is determined whether or not the counted number of areas is greater than or equal to a predetermined value (corresponding to the second predetermined time described above) preset and stored in the ROM of the microcomputer 10. If it is equal to or greater than the predetermined value (in the case of YES), the process proceeds to step S308. If it is less than the predetermined value (in the case of NO), the process proceeds to step S307.

[0067] Next, in step S307, the area in which the focus error signal is observed is small, that is, the time width during which the signal surface of the optical disk crosses the focal point is short, so that the surface blur is small. The servo signal processing unit 5 is instructed to drive the objective lens at a speed (high speed) higher than the speed under the worst condition set in advance, and the process proceeds to step S309.

[0068] Next, in step S308, it is determined that there are many areas where the focus error signal is observed, that is, the time of the optical disc signal surface crossing the focal point is long, so that the surface blur is large. However, the servo signal processing unit 5 is instructed to drive the objective lens at a slow speed (low speed) at which the focus can be drawn, and the process proceeds to step S309.

[0069] Next, in step S309, the area number obtained by subtracting 1 from the smallest area number where the focus error signal was observed (the position where the focus error signal was first observed) is set as the objective lens drive lower limit value. Then go to step S310.

[0070] Next, in step S310, an area number obtained by adding 1 from the largest area number where the focus error signal was observed (the position where the focus error signal was observed last) is set as the objective lens drive upper limit value. . In the subsequent focus pull-in operation, the servo signal processing unit 5 is instructed to set the drive range from the set objective lens drive lower limit value to the objective lens drive upper limit value. For example, in FIG. 9, since the focal points are crossed in areas 5 and 6, the driving range is from 4 to 7. That is, the drive range of the objective lens in the focus pull-in operation is changed according to the area where the focus error signal was first observed and the area where the focus error signal was last observed.

[0071] According to this embodiment, the objective lens is moved once, the moving time is divided into a plurality of areas, the detection of the area where the signal surface of the optical disc crosses the focal point and the number of areas are counted, and the counted area If the number is equal to or greater than the preset value, the surface blur is judged to be large! /, And the objective lens is driven at a low speed, and if it is less than the predetermined value, the surface blur is judged to be small! Drive. The crossed area force drive range can be detected and set, so the drive speed and drive range of the objective lens can be changed according to the amount of surface shake. It is even shorter than just doing it.

[0072] Although the time axis is divided into a plurality of areas in the present embodiment, the focus direction may be divided into a plurality of areas. [0073] Further, in this embodiment, the amount of surface blur was determined by counting the number of areas divided by the time axis. However, since the time axis is divided into a plurality of areas and the number is counted, the second Since it can be said that the time width of the embodiment is measured, the method of the second embodiment may be applied as it is. In addition, the method of dividing the area into the areas to determine the driving range is not changed, and the method of counting the number of crossings in the first embodiment may be combined with the determination of the driving speed.

[0074] In this embodiment, the driving range is a range with a margin for each of the upper and lower limits than the range in which the focus error signal is observed. However, the driving range is not limited to this, and the range in which the focus error signal is observed is driven. It may be a range or allow more than 2 areas. Furthermore, the drive range of only either the upper limit or the lower limit may be limited.

In the first to third embodiments, the focus error signal is used as the signal observed when the focal point crosses the signal surface of the optical disc. However, the return light sum signal and the RF signal are used. Any signal that can be generated by the optical pickup 3 and observed by the servo signal processor 5 when the focal point crosses the signal surface of the optical disk, etc. can be observed. It can be used to judge the amount of quantity.

[0076] In the first to third embodiments, the driving speed is set to two stages of low speed and high speed. However, the driving speed may be three stages or more instead of two stages. If there are three or more stages, set a predetermined value or first predetermined time in the ROM of the microcomputer 10 according to the number of stages.

[0077] In the first to third embodiments, the signal first detected in determining the level difference of the focus error signal is used as a reference. However, the present invention is not limited to this. For example, the signal having the highest or lowest signal level is used as a reference. The signal power may be counted or measured within a predetermined level difference.

[0078] In the first to third embodiments, the DVD, CD, and BD can be played back. However, the present invention is not limited to this, and can be applied to other types of optical disks such as HD-DVD.

According to the embodiment described above, the following objective lens driving device and driving method can be obtained.

[0080] (Appendix 1) Focusing the laser diode and the light from the laser diode on the optical disc 11 The servo signal processing unit 5 includes an objective lens for irradiating the object and a servo signal processing unit 5 that moves the objective lens in a substantially vertical direction with respect to the optical disc 11. The servo signal processing unit 5 observes the focal point on the optical disc 11 by moving a certain range, and the speed at which the servo signal processing unit 5 moves the objective lens to pull the force according to the observation result. An optical disc player 1 comprising a microcomputer 10 to be changed.

According to this optical disc player 1, since the state of the surface shake of the optical disc 11 can be grasped by observing the focal point on the optical disc 11, the focus can be pulled in at a speed corresponding to the amount of the surface shake. If the surface blurring is small, the focus pull-in time can be shortened.

(Additional remark 2) In the objective lens driving method of moving the objective lens for focusing and irradiating the light from the laser diode to the optical disc 11 in the substantially vertical direction with respect to the optical disc 11, the objective lens is moved. A method of driving an objective lens, characterized by observing a focal point on the optical disk 11 by moving a certain amount and changing a speed of driving the objective lens to perform focus pull-in according to the observed result.

[0083] According to this objective lens driving method, since the state of the surface blur of the optical disk 11 can be grasped by observing the focal point on the optical disk 11, the focus pull-in is performed at a speed according to the amount of the surface blur. If there is little surface blur, the focus pull-in time can be shortened.

It should be noted that the above-described embodiments are merely representative forms of the present invention, and the present invention is not limited to the embodiments. That is, various modifications can be made without departing from the scope of the present invention.

Claims

The scope of the claims

[1] Objective lens drive comprising: a light source; an objective lens for irradiating light from the light source with focusing on the optical disk; and a driving means for moving the objective lens in a substantially vertical direction with respect to the optical disk. In the device

The drive means moves the objective lens within a certain range, causes the observation means to observe the focal point on the optical disc, and the drive means moves the objective lens to perform focus pull-in according to the observation result. An objective lens driving device comprising: a control means for changing.

[2] The control means increases the speed of driving the objective lens when the number of times crossing the focal point on the optical disk is less than a predetermined value as a result of observation by the observation means, 2. The objective lens driving device according to claim 1, wherein a speed of driving the objective lens is decreased when the value is larger than the value of.

[3] The control means, when the observation means observes, when the time width until the force finally crosses the focal point on the optical disc is shorter than a predetermined first predetermined time. 2. The objective lens driving device according to claim 1, wherein the driving speed of the objective lens is increased, and the driving speed of the objective lens is decreased when the driving speed is longer than the first predetermined time.

[4] The control means first causes the position acquisition means to acquire the position of the objective lens when the observation means observes the focal point on the optical disc, and first moves the objective lens within a certain range. 4. The driving range for performing focus pull-in of the objective lens is changed according to a position where the focal point is observed and a position where the focal point is finally observed. The objective-lens drive device of description.

[5] The control unit divides the fixed range into a plurality of ranges, and changes a driving range when performing focus pull-in of the objective lens according to a range where the in-focus point exists in the plurality of ranges. 5. The objective lens driving device according to claim 4, wherein

[6] When a plurality of in-focus points on the optical disc observed by the observation unit are observed within a second predetermined time that is determined in advance, the control unit observes within the second predetermined time. 3. The objective according to claim 2, wherein the plurality of in-focus points are counted as one. Lens drive device.

[7] The control means targets only a focal point in which the intensity of reflected light from the optical disc is within a predetermined range among a plurality of focal points on the optical disc observed by the observation unit. The objective lens driving device according to claim 2 or 3.

[8] The method according to any one of claims 1 to 7, wherein the observation means sets a position where one or more of a focus error signal, an RF signal, and a return light total signal are observed as a focal point. An objective lens driving device according to any one of the deviations.

[9] An objective lens driving method for moving an objective lens for irradiating light having a light source power with focusing on the optical disk in a substantially vertical direction with respect to the optical disk, and

An objective lens drive characterized by observing a focal point on the optical disc by moving the objective lens by a certain amount, and changing a speed at which the objective lens is driven to perform focus pull-in according to the observed result. Method.

[10] The position of the objective lens when the focal point on the optical disk is observed is acquired, and the focal point is first observed when the objective lens is moved within a certain range, and finally the focal point is obtained. 10. The objective lens driving method according to claim 9, wherein a driving range when performing focus pull-in of the objective lens is changed according to an observed position.