JP3947966B2 - Optical disc apparatus and focus control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical disk instrumentation 置及 beauty focus control method, and is suitably applied to, for example, an optical disk reproducing apparatus for reproducing video data recorded in the DVD (Digital Versatile Disk).
[0002]
[Prior art]
Conventionally, as shown in FIG. 4, the optical disc reproducing apparatus 1 condenses the light beam R emitted from a predetermined light source (not shown) through the objective lens 3 and is sequentially provided in the thickness direction of the DVD 2. Irradiate one of the first layer recording surface 2A and the second layer recording surface 2B.
[0003]
When starting playback, the optical disc playback apparatus 1 gradually moves the objective lens 3 in a direction approaching the DVD 2 from a predetermined search start position BP that is a predetermined distance from the DVD 2, so that the first layer recording surface 2 A Video data obtained based on the reflected light (not shown) of the light beam R on the first-layer recording surface 2A or the second-layer recording surface 2B in focus by focusing on the two-layer recording surface 2B. Has been made to play.
[0004]
[Problems to be solved by the invention]
By the way, in the optical disk reproducing apparatus 1 having such a configuration, when the focus f that follows the second layer recording surface 2B is deviated, the objective lens 3 is moved to a proximity position P1 closer to the DVD 2 than the position at that time. Thereafter, a position P2 where the focus f is in focus on the second layer recording surface 2B is searched while moving from the proximity position P1 toward the search start position BP.
[0005]
However, in the optical disc reproducing apparatus 1, for example, if the DVD 2 is decentered, the objective lens 3 moved to the proximity position P1 may be brought into contact with the DVD 2 and damaged.
[0006]
The present invention has been made in view of the above, it is intended to propose an optical disc instrumentation 置及 beauty focus control method that can avoid damage to the objective lens almost certainly.
[0007]
[Means for Solving the Problems]
The present invention for solving the above problems is for one of the recording surfaces of the plurality of recording surface provided on an optical disc, there is provided an optical disk apparatus to follow the focus of the light beam through the objective lens, one recording surface Detecting means for detecting whether or not the focal point being followed is deviated, and one of the plurality of recording surfaces is followed by one recording surface excluding the outermost recording surface provided on the side irradiated with the light beam. If you are focus is detected by the detection means that the outside in a predetermined search time, the objective lens is moved from a predetermined distance away search start position from the optical disk in a direction closer to the optical disc, the outermost layer by the detection means when detecting that focus on the recording surface, a focus search means for searching a focus for one recording surface of the focus is out, the search time, the outermost through the sensing unit When not detect that-focus on the recording surface, and to provide a notification means for notifying that there is a risk of scratches or eccentric to the optical disc.
[0009]
The present invention is also a focus control method for irradiating an optical disc after a light beam emitted from a light source is collected by an objective lens and moving the objective lens based on a light amount signal corresponding to the amount of reflected light. , among the plurality of recording surfaces, if the focus light beam is tracking on one of the recording surface, except for the recording surface of the outermost layer provided on the side to be irradiated is tested knowledge that out, predetermined search In time, a first focus search step for searching the focal point with respect to the outermost layer recording surface by moving the objective lens from a search start position that is a predetermined distance away from the optical disc to a direction closer to the optical disc, and focusing on the outermost layer recording surface when is detected that there was a second focus search step of searching the focus for one recording surface of the focus is out, the search time, the recording of the outermost layer When not detect that had focus, and to provide a notification step of notifying that there is a risk of scratches or eccentric to the optical disc.
[0010]
Therefore, the present invention focuses on the one recording surface that is out of focus after confirming that the optical disc is not scratched or decentered because the recording surface of the outermost layer is in focus. since, it is possible to substantially reliably electrically controlled that would in contact with the optical disk objective lens focus for one recording surface of the focus out is moving in the direction toward the optical disk because they are not detected.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
[0012]
In FIG. 1, reference numeral 10 denotes an optical disk reproducing apparatus to which the present invention is applied as a whole, and according to various programs stored in an internal memory (not shown) of the microcomputer 11 by a microcomputer (hereinafter referred to as a microcomputer) 11. The optical disc playback apparatus 10 is controlled in an integrated manner.
[0013]
The microcomputer 11 rotates and drives a DVD (Digital Versatile Disk) 12 having first and second recording surfaces via a spindle motor (not shown) and a light source 14 as a light source provided in the optical pickup 13. The light beam R1 is emitted by driving.
[0014]
The light beam R1 passes through a grating lens 15 provided in the optical pickup 13, is bent by a beam splitter 16, and is then collected by an objective lens 17 as an optical lens to be first or second of the DVD 12. Irradiates the recording surface.
[0015]
Then, the reflected light R1 obtained by reflecting the light beam R1 on the first or second recording surface passes through the beam splitter 16, the collimator lens 18 and the cylindrical lens 19 in order, and the light receiving surface (not shown) of the photodetector 20. ).
[0016]
The photodetector 20 generates a light amount signal S1 corresponding to the light amount of the reflected light R1 received by the light receiving surface, and sends it to the RF amplifier 21.
[0017]
The RF amplifier 21 generates a tracking error signal S2, a focus error signal S3, and an RF signal S4 based on the light amount signal S1.
[0018]
The RF amplifier 21 sends the tracking error signal S2 to the tracking driver 23 via the DSP 22 (Digital Signal Processor), sends the focus error signal S3 to the focus driver 24 via the DSP 22, and further sends the RF signal S4 to the DSP 22. To send.
[0019]
The DSP 22 performs analog-digital conversion processing on the RF signal S4 to generate compressed reproduction data D2, and sends this to the demodulator 25.
[0020]
The demodulator 25 generates video data D3 by subjecting the compressed reproduction data D2 to decoding processing in accordance with a compression coding standard called MPEG (Moving Picture Experts Group), for example, and generates this video data D3. / A) The video signal S4 is sent to the display unit (not shown) via 26.
[0021]
As a result, the optical disc reproducing apparatus 10 can display the video based on the video signal S4 reproduced from the DVD 12 on the display unit.
[0022]
On the other hand, the tracking driver 23 appropriately moves the objective lens 17 of the optical pickup 13 in the radial direction of the DVD 12 indicated by an arrow a by controlling the lens driving unit 27 based on the tracking error signal S2 supplied from the DSP 22.
[0023]
As a result, the tracking driver 23 tracks the focal point f1 of the light beam R1 on the target track of the DVD 12 via the lens driving unit 27.
[0024]
The focus driver 24 performs focus servo control based on the focus error signal S3 supplied from the DSP 22.
[0025]
That is, the focus driver 24 moves the objective lens 17 from the DVD 12 along the optical axis of the light beam R1 via the lens driving unit 27 as shown by the arrow b according to the movement amount and direction according to the signal level of the focus error signal S3. The distance between the objective lens 17 and the first or second layer recording surface is adjusted by appropriately moving it away (hereinafter referred to as the far direction) or moving closer to the DVD 12 (hereinafter referred to as the near direction). As a result, the focal point f1 of the light beam R1 follows the recording surface of the DVD 12.
[0026]
Therefore, in the optical disc reproducing apparatus 10, the video signal S4 reproduced from the DVD 12 can be obtained accurately, and as a result, a high quality video can be displayed on the display unit.
[0027]
By the way, when the focal point f1 of the light beam R1 that follows the first or second layer recording surface of the DVD 12 deviates, the amount of reflected light R1 obtained by reflecting the light beam R1 on the recording surface is extremely small. Therefore, the RF amplifier 21 cannot generate the focus error signal S3 based on the light amount signal S1 obtained via the photodetector 20, and does not send the focus error signal S3 to the focus driver 24.
[0028]
In this case, since the focus driver 24 cannot detect the focus error signal S3 for a predetermined period, it detects that the focus f1 of the light beam R1 that follows the recording surface of the DVD 12 is out of focus.
[0029]
At this time, the focus driver 24 executes focus search control for searching the recording surface of the DVD 12.
[0030]
That is, as shown in FIG. 2, the focus driver 24 has a focal point f1 that follows the first layer recording surface 12A among the first layer recording surface 12A and the second layer recording surface 12B that are sequentially provided in the thickness direction of the DVD 12. Is detected, the objective lens 17 is moved in the far direction along the optical axis La of the light beam R1 at the time of detection, thereby returning the search start position bp from the DVD 12 to a predetermined distance dis.
[0031]
Thereafter, the focus driver 24 searches the focal point f1 with respect to the first layer recording surface 12A by moving the objective lens 17 in the near direction from the search start position bp without changing the optical axis La.
[0032]
In this case, as the objective lens 17 approaches the first layer recording surface 12A, the amount of light received by the photodetector 20 (FIG. 1) increases, so that the RF amplifier 21 (FIG. 1) is obtained via the photodetector 20. A focus error signal S3 is generated again based on the received light amount signal S1, and is sent to the focus driver 24.
[0033]
Here, when the focus driver 24 detects that the focus f1 is in focus on the first layer recording surface 12A based on the focus error signal S3, the focus driver 24 executes focus servo control again to change the focus f1 of the light beam R1 to the first layer. It is made to follow the recording surface 12A.
[0034]
On the other hand, the focus driver 24 stops the reproduction when it is not detected within a predetermined period that the focus f1 is focused on the first layer recording surface 12A.
[0035]
On the other hand, the focus driver 24 also executes the focus search control when detecting that the focus f1 that follows the second layer recording surface 12B is off, and first searches for the focus f1 with respect to the first layer recording surface 12A. It is made like that.
[0036]
Only when the focus driver 24 detects that the focus f1 is in focus on the first layer recording surface 12A, the position of the objective lens 17 at the time of detection (hereinafter referred to as the first layer recording surface detection position). The focal point f1 with respect to the second layer recording surface 12B is searched by moving the objective lens 17 in the near direction along the optical axis La from the RTP.
[0037]
Here, in the DVD 12, when flaws and eccentricity occur, it is common that the focal point f1 does not match either the first layer recording surface 12A or the second layer recording surface 12B. When the focus f1 is focused on the first layer recording surface 12A even though the focus f1 following the layer recording surface 12B is off, vibration or the like is a factor.
[0038]
Therefore, since the focus driver 24 detects that the focus f1 is in focus on the first layer recording surface 12A, the focus f1 can be almost surely focused on the second layer recording surface 12B.
[0039]
Thus, the focus driver 24 electrically controls the objective lens 17 without using a stopper (not shown) provided near the DVD 12 in order to mechanically avoid contact between the DVD 12 and the objective lens 17. Contact is almost certainly avoided.
[0040]
Thus, in the optical disk reproducing apparatus 10, not only the damage caused by bringing the objective lens 17 into contact with the DVD 12 is almost certainly avoided, but also the shake of the optical system caused by being brought into contact with the stopper is almost certainly avoided. The mechanical durability of the entire optical disc playback apparatus 10 can be improved.
[0041]
In the optical disc reproducing apparatus 10, when the focus control processing procedure when following the second layer recording surface 12B is summarized using the flowchart shown in FIG. 3, the microcomputer 11 performs step SP1 following the start step of the routine RT. Move on.
[0042]
In step SP1, the microcomputer 11 executes focus servo control and determines whether or not the focus f1 of the light beam R1 tracking the second layer recording surface 12B of the DVD 12 (FIG. 3) is out of focus based on the focus error signal S3. to decide.
[0043]
If a negative result is obtained here, this indicates that the focal point f1 can follow the second layer recording surface 12B. At this time, the microcomputer 11 continues to follow the focal point f1 to the second layer recording surface 12B. Let
[0044]
On the other hand, if a positive result is obtained, the microcomputer 11 detects that the focus f1 that follows the second-layer recording surface 12B is off, and proceeds to the subsequent step SP2.
[0045]
In step SP2, the microcomputer 11 shifts from focus servo control to focus search control, moves the objective lens 17 to the search start position bp (FIG. 2) along the optical axis La when detected in step SP1, and then continues to step SP3. Move on.
[0046]
In step SP3, the microcomputer 11 starts the search for the focal point f1 with respect to the first layer recording surface 12A by moving the objective lens 17 in the near direction from the search start position bp along the optical axis La, and then proceeds to step SP4.
[0047]
In step SP4, the microcomputer 11 determines whether or not the focus f1 of the light beam R1 is focused on the first layer recording surface 12A based on the focus error signal S3. If a negative result is obtained here, this indicates that the focal point f1 is not yet in focus on the first layer recording surface 12A. At this time, the microcomputer 11 proceeds to step SP5.
[0048]
In step SP5, the microcomputer 11 determines whether or not a predetermined search time has elapsed since the start of the search for the focus f1 with respect to the first layer recording surface 12A in step SP3. If a negative result is obtained here, the microcomputer 11 returns to step SP4.
[0049]
In this way, the microcomputer 11 moves the objective lens 17 in the near direction along the optical axis La in step SP3 until a positive result that the search time elapses is obtained in step SP5.
[0050]
Here, based on the moving speed of the objective lens 17 and the maximum distance dis1 (FIG. 2) from the search start position bp to the DVD 12, the microcomputer 11 stops the search before the objective lens 17 contacts the stopper. Possible search time is set.
[0051]
As a result, the microcomputer 11 can almost certainly avoid contacting the objective lens 17 with the DVD 12 or the stopper without searching for the focal point f1 with respect to the recording layer 12A of the first layer in the DVD 12 in which scratches and eccentricity occur. Has been made.
[0052]
Therefore, if a positive result is obtained that the search time elapses in step SP5, the microcomputer 11 moves to the subsequent step SP6, stops reproduction before the objective lens 17 and the stopper come into contact, and damages the objective lens 17. In addition to avoiding this, it is possible to avoid blurring of the optical system in the optical disc reproducing apparatus 10.
[0053]
At this time, the microcomputer 11 can notify the user that the DVD 12 may be damaged or eccentric via a speaker (not shown) or a display unit (not shown).
[0054]
On the other hand, if an affirmative result in which the focal point f1 of the light beam R1 is in alignment with the first layer recording surface 12A is obtained in step SP4, this indicates that the DVD 12 is not scratched or decentered. Within the remaining search time, the objective lens 17 is moved in the near direction along the optical axis La from the first layer recording surface detection position RTP (FIG. 2) to search for the second layer recording surface 12B.
[0055]
In this case, since the microcomputer 11 detects the first layer recording surface 12A in advance and confirms in advance that the DVD 12 is not scratched or decentered, the second layer recording surface 12B is searched for. Since it is almost possible to avoid searching for the focal point f1 with respect to the recording surface 12B, the focal point f1 with respect to the second layer recording surface 12B can be almost certainly searched without bringing the objective lens 17 into contact with a stopper provided in the vicinity of the DVD 12. Has been made.
[0056]
Thereafter, the microcomputer 11 ends the focus search control, returns to step SP1, and executes focus servo control again.
[0057]
Incidentally, when executing the focus servo control, the microcomputer 11 shifts to the focus search control when detecting that the focus f1 of the light beam R1 following the first layer recording surface 12A is out of focus. After the objective lens 17 is moved to the search start position bp (step SP2), the search for the focal point f1 with respect to the first layer recording surface 12A is started (step SP3).
[0058]
Then, when the focus f1 is in focus on the first layer recording surface 12A (step SP4), the microcomputer 11 again shifts from focus search control to focus servo control, and moves the objective lens 17 at the first layer recording surface detection position RTP. In contrast, when the search cannot be performed before the search time has elapsed (step SP5), the reproduction is stopped (step SP6).
[0059]
In the above configuration, the microcomputer 11 as the detection unit controls the focus driver 24 and follows the second layer recording surface 12B based on the focus error signal S3 obtained from the light amount signal S1 detected by the photodetector 20. It is detected whether the focus f1 of the light beam R1 being deviated or out of focus.
[0060]
In this state, when it is detected that the focus f1 of the light beam R1 that follows the second-layer recording surface 12B is out of focus, the microcomputer 11 as focus search means shifts to focus search control, and the focus driver 24 By moving the objective lens 17 in the near direction from the search start position bp via the lens drive unit 27, the focus is first focused on the first layer recording surface 12A without focusing on the second layer recording surface 12B. The focus f1 is adjusted to the second layer recording surface 12B only when it is detected that the focus f1 is adjusted to the first layer recording surface 12A.
[0061]
Therefore, the microcomputer 11 confirms that there is no scratch or eccentricity that has occurred in the DVD 12 as a factor that the focus f1 that follows the second layer recording surface 12B is out of focus because the focus f1 is on the first layer recording surface 12A. Since the focus f1 is focused on the second layer recording surface 12B after confirmation, it is possible to avoid contacting the objective lens 17 with a mechanical stopper without searching for the focus f1 with respect to the second layer recording surface 12B. Can do.
[0062]
In this case, the microcomputer 11 can almost certainly avoid contact with the DVD 12 without using a mechanical stopper by electrical control.
[0063]
In addition to this, the microcomputer 11 as the focus search means, when the focus f1 on the first layer recording surface 12A is adjusted, the first layer recording surface 12A within the search time set for avoiding contact of the objective lens 17 with the DVD 12. Alternatively, the focal point f1 of the first layer recording surface 12A and the second layer recording surface 12B is searched.
[0064]
In this case, the microcomputer 11 focuses the second layer recording surface 12B on the second layer recording surface 12B within the remaining search time only when it is detected that the first layer recording surface 12A is in focus f1. It is possible to omit the setting in the search time when the focus f1 is focused on the layer recording surface 12B.
[0065]
Therefore, in the microcomputer 11, the electric power can be simplified compared with the case where the focus f1 is focused on each recording surface 12A and 12B within each search time set individually for the first layer recording surface 12A and the second layer recording surface 12B. Even if the difference between the first layer recording surface detection position RTP and the position of the objective lens 17 when the focal point f1 is focused on the second layer recording surface 12B is several hundreds [nm], the mechanical control is performed. It is possible to almost certainly avoid contact with the DVD 12 without using a typical stopper.
[0066]
According to the above configuration, the microcomputer 11 first focuses the first layer recording surface 12A by f1 even when the focus f1 of the light beam R applied to the second layer recording surface 12B is deviated, and the first layer. By confirming that there is no scratch or eccentricity on the DVD 12 because the focal point f1 is in focus on the recording surface 12A, the focal point f1 is adjusted on the second layer recording surface 12B. It is possible to almost certainly avoid contact with the DVD 12 without using the mechanical stopper while the focal point f1 with respect to the recording layer 12B of the second layer cannot be searched. It can be avoided.
[0067]
In the above-described embodiment, the case where the reproduction is stopped when the search time has elapsed by the microcomputer 11 as the focus search means has been described. However, the present invention is not limited to this, and so-called retry is performed. Also good.
[0068]
In this case, the microcomputer 11 can improve the accuracy of the notification that the DVD 12 may be damaged or eccentric.
[0069]
In the above-described embodiment, the case where the DVD 12 having the two recording surfaces of the first layer recording surface 12A and the second layer recording surface 12B is used has been described. However, the present invention is not limited to this, and the first embodiment Various optical disks having a plurality of recording surfaces from the layer recording surface to the nth layer recording surface can be used.
[0070]
Further, in the above-described embodiment, the case where the present invention is applied to the optical disk reproducing apparatus 10 has been described. However, the present invention is not limited to this, and an optical disk recording apparatus, an optical disk recording / reproducing apparatus, a magneto-optical disk apparatus, and an optical disk are used. The present invention can be applied to various other optical disk apparatuses such as a projector apparatus or a combined optical disk apparatus that can be used with, for example, a DVD 12 and a CD (Compact Disk).
[0071]
In this case, the distance dis2 (FIG. 2) between the position of the objective lens 17 when the focus f1 is focused on the second layer recording surface 12B and the surface 12C on the recording surface side of the DVD 12 is different because the wavelength of the light beam R1 is different. If the present invention is applied to a combined type optical disc apparatus designed to be narrow, the recording surfaces 12A and 12B are individually recorded within each search time set individually for the first layer recording surface 12A and the second layer recording surface 12B. Since the electric control is simpler than the case where the focus f1 is focused on, contact with the DVD 12 can be almost certainly avoided without using a mechanical stopper, which is particularly effective.
[0072]
【The invention's effect】
According to the present invention as described above, after confirming that the optical disc on the grounds that the focus on the outermost layer of the recording surface does not occur scratches and eccentricity, one recording surface of the focus is out the by you to focus, almost certainly electrically that would in contact with the optical disc of the objective lens in which the focus for one recording surface which focus out is moved in a direction toward the optical disk because we are not detected Thus, damage to the objective lens can be almost certainly avoided.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an optical disc reproducing apparatus to which the present invention is applied.
FIG. 2 is a schematic diagram illustrating a state of a focus control process.
FIG. 3 is a flowchart showing a focus control processing procedure.
FIG. 4 is a schematic diagram showing a state of a conventional focus control process.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Optical disk reproducing apparatus, 11 ... Microcomputer, 12 ... DVD, 12A ... First layer recording surface, 12B ... Second layer recording surface, 13 ... Optical pickup, 14 ... Light source, 17 ... Objective Lens 20... Photodetector 21. RF amplifier 22. DSP 23. Tracking driver 24. Focus driver 27.

Claims (3)

In an optical disc apparatus that follows a focal point of a light beam via an objective lens with respect to one recording surface of a plurality of recording surfaces provided on an optical disc,
Detecting means for detecting whether or not the focal point following the one recording surface is out of focus;
Of the plurality of recording surfaces, the detection means detects that the focus following the one recording surface excluding the outermost recording surface provided on the side irradiated with the light beam is off. If, in a given search time, a predetermined distance away search start position from the optical disk in a direction closer to the optical disc by moving the objective lens, that focus on the recording surface of the outermost layer by the detection means A focus search means for searching for a focal point for one recording surface out of focus when detected;
And notifying means for notifying that there is a risk of scratches or eccentricity on the optical disc when the detection means does not detect that the recording surface of the outermost layer is in focus during the search time. Optical disk device to perform. The above search time is
2. The optical disc apparatus according to claim 1, wherein the search time is not a search time for each of the plurality of recording surfaces but a search time for avoiding contact of the objective lens with the optical disc. In a focus control method in which a light beam emitted from a light source is condensed by an objective lens and then irradiated onto an optical disc, and the objective lens is moved based on a light amount signal corresponding to the amount of reflected light.
Among the plurality of recording surfaces provided on the optical disc, the focus of the light beam is tracking on one of the recording surface, except for the recording surface of the outermost layer provided on the side to be irradiated is tested knowledge that deviated A first focus search step of searching for the focal point with respect to the recording surface of the outermost layer by moving the objective lens from a search start position that is a predetermined distance away from the optical disc in a direction approaching the optical disc at a predetermined search time. When,
A second focus search step for searching for a focus with respect to one recording surface that is out of focus when it is detected that the recording surface of the outermost layer is in focus;
A focus control method comprising: a notification step for notifying that there is a risk of scratching or eccentricity of the optical disc when it is not detected that the recording surface of the outermost layer is in focus during the search time. .

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