JP4366326B2 - Optical information recording / reproducing apparatus - Google Patents

Description

  The present invention relates to an optical information recording / reproducing apparatus using two or more layers of optical media, and more particularly to control of spherical aberration generating means and control of seek operation.

  A DVD is an example of a currently known multilayer disk.

  In DVD, when accessing from one address position of the first layer to another address position of the second layer, a radial movement from the current address position to the target address position is performed by seeking, The disc moves in the thickness direction from the current layer to the target layer by focus jump.

  In general, if there is an error from the design value in the thickness of the optical disk substrate (light transmission layer), spherical aberration occurs, and the spot quality on the optical recording medium deteriorates (the spot size changes, and the peak intensity is relatively high). It is known that the recording / reproducing performance decreases. Further, it is known that the amount of generated spherical aberration is approximately proportional to the fourth power of the objective lens NA and inversely proportional to the wavelength.

  In recent years, in an optical disk apparatus, the oscillation wavelength of a semiconductor laser has become shorter and the objective lens used has a higher NA. For example, in a BD (Blu-ray Disc) device, the wavelength is 405 nm and the objective lens NA is 0.85.

  Therefore, in the case of a BD device, spherical aberration is very likely to occur compared to a DVD device, etc., and when the optical disk is replaced, when the recording / playback position changes greatly even with the same optical disk, or in a multi-layer disk, When moving from one layer to another, it is necessary to correct the spherical aberration.

  Various devices for correcting the spherical aberration have been proposed.

  For example, according to Japanese Patent Laid-Open No. 2002-312971, two lenses are arranged between a collimator lens and an objective lens as spherical aberration correction means, and one lens is moved in the direction of the optical axis by a DC motor, and the lens interval is increased. Means for generating spherical aberration by making it variable have been proposed.

  Japanese Patent Laid-Open No. 10-269611 proposes spherical aberration generating means using liquid crystal.

  In such a multi-layer disc, when accessing from one address position of the first layer to another address position of the second layer, the target address is determined from the current address position as in the case of DVD. The movement in the radial direction to the position is performed by seek, the movement in the thickness direction of the disk from the current layer to the target layer is performed by the focus jump, and the state of the spherical aberration by the spherical aberration generating means is determined by the current layer. It is necessary to drive from the optimum state to the optimum state for the target layer.

  In order to drive the spherical aberration generating means from the optimum state for the current layer to the optimum state for the other layers, the system comprising the above-mentioned two lenses, with one lens being driven by a motor, several hundred mS In the method of driving the liquid crystal, a time of several tens of milliseconds is required.

This means an increase in access time of several tens of milliseconds to several hundreds of milliseconds compared to the case of a DVD or the like.
JP 2002-312971 A Japanese Patent Laid-Open No. 10-269611

  The increase in the access time as described above is a fatal defect for a peripheral device such as a computer whose access time affects the performance.

  Therefore, an object of the present invention is to enable access while suppressing an increase in access time due to driving of spherical aberration generating means in accessing a multilayer disk.

  The above-mentioned subject is achieved by the following invention.

In order to solve the above problems, the present invention provides:
For each recording layer of an optical recording / reproducing medium having a plurality of recording layers, an objective lens for generating a focused spot with a light beam from a light source, and an optical path between the light source and the objective lens are disposed. A spherical aberration generating means for generating a spherical aberration for canceling the spherical aberration in the luminous flux in order to correct the spherical aberration generated when the condensing spot is moved to the selected recording layer; Optical information having first driving means for moving an optical head including an objective lens in the radial direction of the medium, and second driving means for moving the focused spot between the recording layers. recording in the reproduction apparatus, when accessing the focusing spot to a target address position on the current address the different from the position recording layer, the spherical aberration generating means and the first driving means Prior to driving, the second drives the driving means, the optical information recording and reproducing apparatus, wherein said driving the spherical aberration generating means during driving of the first driving means.

  According to the present invention, it is possible to suppress the access time required to drive the spherical aberration generating means when accessing the target address from the current address of the focused spot between the layers of the multilayer disk.

(First embodiment)
FIG. 1 is a block diagram of an optical information recording / reproducing apparatus according to the present invention.

  In the figure, 1 is an optical disk, 2 is an optical head, 3 is an error signal generation circuit for calculating the output of a photodetector in the optical head and outputting various signals, and 4 is a focus error signal among the output signals of the arithmetic circuit 3 Is a focus control circuit, 5 is a driver circuit for driving a focus actuator in the optical head, 6 is a track control circuit for inputting a track error signal among output signals of the error signal generation circuit 3, and 7 is an optical signal. A driver circuit for driving the track actuator in the head, 8 is a head feeding stepping motor for moving the entire optical head 2 in the disk radial direction, 9 is a driver circuit for driving the head feeding stepping motor, 10 Is a driver circuit for driving a stepping motor for generating spherical aberration in the optical head 2, 11 Servo controller, 12 a system controller, 13 is a spindle.

  The optical head 2 is configured as shown in FIG.

  In FIG. 2, the beam emitted from the semiconductor laser 101 is divided into three beams by the diffraction grating 102, converted into parallel light by the collimator 103, and enters the polarizing beam splitter 104 with beam shaping. A part of the beam is reflected, enters the APC sensor 105, and is used to monitor the amount of light emitted from the semiconductor laser 101. The transmitted beam is condensed on the recording layer surface via the light transmission layer on the optical disk 1 by the objective lens 112 via the quarter-wave plate 106, the lens 107, and the lens 108, and is used for reproducing and recording information. The The beam reflected by the optical disc 1 is reflected by the polarization beam splitter 104 with beam shaping, enters the photodetector 115 via the sensor lens 114, and is used for reproducing the information signal.

  Here, the lens 107 is fixed, and the lens 108 is held by the electromagnetic driving means 110 so that the distance between the lens 107 and the lens 107 in the optical axis direction is variable, thereby forming the spherical aberration generating means 111. The shape of the lens 107 and the lens 108 and the glass material are configured such that only spherical aberration occurs when the lens interval changes. The electromagnetic driving means 110 moves the lens 108 on the micron order with a lead screw using a stepping motor.

  The output of the photodetector 115 is calculated by the error signal generation circuit 3 and output as a focus error signal, a track error signal, an RF signal, or the like. Of these signals, the focus error signal is connected to the focus actuator in the optical head 2 via the focus control circuit 4 and the driver circuit 5 to form a focus control loop. The track error signal is connected to the tracking actuator in the optical head 2 via the track control circuit 6 and the driver circuit 7 to form a track control loop.

  Among the outputs of the error signal generation circuit 3, the RF signal is input to an RF signal processing circuit (not shown), and an information signal, a disk address signal, etc. are detected and input to the system controller 12.

  The servo controller 11 controls the focus control circuit 4 and the track control circuit 6 to open / close a loop and generate a jump signal.

The servo controller 11 controls the stepping motor 8 by the driver 9 to move the optical head 2 to a desired radial position.

  The servo controller 11 controls the spherical aberration generating means 111 shown in FIG. 2 in the optical head 2 to adjust the spherical aberration to an optimum state by controlling the driver circuit 10.

  Next, the access method in the present embodiment will be described with reference to the flowchart of FIG.

  In the optical information recording / reproducing apparatus of this embodiment, focus and tracking control are applied, and the beam is focused on a track at a certain radial position of a certain layer.

  When the system controller 12 receives a reproduction command to a predetermined address from a host device (not shown), the system controller 12 calculates the radial distance between the current address and the target address, and whether it is the first layer or the second layer. to decide.

When the radial distance and layer are known, the system controller 12 instructs the servo controller 11 on the distance, direction and target layer to be moved. (S1)
The servo controller 11 receives distance and direction information and a layer command, and first determines whether the layer is different from the current layer. (S2)
If the layers are different, the servo controller 11 controls the track control circuit 6 and turns off the track control. (S3)
Next, it is determined whether the distance is a distance that requires moving the optical head. (S4)
When it is necessary to move the optical head, the servo controller 11 sets the number of steps to be moved, and starts to drive the stepping motor 8 by the driver 9, and at the same time, sets the number of movement steps of the stepping motor for generating spherical aberration to the target layer. And the driver 10 starts driving the stepping motor for generating spherical aberration. (S5)
When it is not necessary to move the optical head, the servo controller 11 sets the number of moving steps of the stepping motor for generating spherical aberration to the number of steps to the target layer, and the driver 10 drives the stepping motor for generating spherical aberration. Start. (S6)
Steps S3 to S6 are instantaneously performed by the servo controller.

Next, the servo controller 11 controls the focus control circuit 4 to perform a focus jump by giving a focus jump pulse to the focus actuator. (S7)
After the focus jump is completed, the servo controller 11 confirms that the stepping motor for generating spherical aberration and the stepping motor for moving the optical head have been driven by a predetermined number of steps, and (when passing through S6, The track control circuit 6 is controlled to turn on the track control. (S8) FIG. 4 shows a timing chart of each control signal from S3 to S8 via S5. Immediately after the track control is turned off (S3), the optical head movement and the movement of the spherical aberration element are started (S5), and then a focus jump is performed (S7). When the optical head movement and the spherical aberration element movement are completed, the track control is turned on ( S8). FIG. 4 shows an example in which the time for moving the optical head is longer than the time for moving the spherical aberration element, but the reverse may occur depending on the access distance. When passing through S6, since the optical head does not move, the track control is turned on when the movement of the spherical aberration element is completed. The focus jump is performed at a timing at which the focus jump ends after the start of the optical head movement and the movement of the spherical aberration element and before the end of each movement time.

  In this state, the beam will be near the target track of the target layer. In order to move further to the target track, the system controller 12 reads the current address again and commands the servo controller 11 to determine the distance from the target address (S1).

  This time, since the layers are the same, only the distance will be judged.

Next, it is determined whether the distance is a distance that requires moving the optical head. (S9)
When it is necessary to move the optical head, the servo controller 11 controls the track control circuit 6 to turn off the track control, and at the same time sets the number of steps to move, drives the stepping motor 8 by the driver 9, and sets the number of target steps. Then, the track control circuit is controlled to turn on the track control. (S10)
When the distance does not require the optical head to be moved, track jump is performed by the track actuator by the number of tracks corresponding to the distance. (S11)
The above operation is repeated, and the reproduction operation is performed when the target track is reached.

In this embodiment, when the spherical aberration generating element is operated, it is performed simultaneously with the movement of the optical head. Therefore, the spherical aberration generating element moving time which takes several hundreds mS and the optical head moving time which takes about the same time are set. It can be operated efficiently without adding together.

  While the optical head is moving, the spherical aberration element may be different from the optimum position in the current layer, which may cause a signal degradation such as tracking error. In this embodiment, the number of steps of the stepping motor Therefore, it is not necessary to worry about the quality of the tracking error signal as in the case where the moving operation is performed using the track count.

  Further, since the track control is not turned on until the focus jump is completed after the track control is first turned off, there is no problem even if the quality of the track error signal is deteriorated depending on the state of the spherical aberration. In addition, when the track control is on, the spherical aberration is in an optimal state, so there is no problem when the track control is on.

  Further, the optical head moving means may be a motor with an encoder that can recognize the moving position instead of a stepping motor. In this case, the optical head can be moved regardless of the quality of the tracking error.

  In this embodiment, the focus jump start timing is after the optical head movement and the movement of the spherical aberration generating element. However, the focus jump is started after the optical head movement and the movement of the spherical aberration generating element are completed. A jump (S7) may be performed.

  FIG. 5 shows a timing chart in such a case. Immediately after the track control is turned off (S3), the movement of the optical head and the movement of the spherical aberration element are started (S5), and after the movement of the optical head and the movement of the spherical aberration element is completed, a focus jump is performed (S7). )is doing. FIG. 5 shows an example in which the time for moving the optical head is longer than the time for moving the spherical aberration, but the reverse may occur depending on the access distance. When passing through S6, since the optical head does not move, the focus jump is performed and the track control is turned on when the movement of the spherical aberration element is completed.

  In this case, the access time is extended by the time of the focus jump, but there is no vibration due to the movement of the optical head, and the spherical aberration is optimal for the target layer, so a stable focus jump can be expected. Also, since the time for focus jump is usually about several milliseconds, the time does not increase greatly.

  In this embodiment, the configuration of the spherical aberration generating means is a method in which two lenses are used and one of them is driven by a stepping motor. However, this method is a method in which spherical aberration is generated by liquid crystal. May be.

  In addition, the determination of whether or not to move the optical head is simply the distance to the target track, but if the relative position between the optical head and the objective lens can be detected, the target from the center position of the optical head can be detected. It is also possible to calculate the distance to the track and make a judgment based on it.

  In this case, it is possible to make an accurate determination considering that the objective lens returns to the center when the track control is off.

  The embodiment is an example at the time of reproduction, but the case of recording is the same as the reproduction until reaching the target track.

  In the present embodiment, the two controllers of the servo controller 11 and the system controller 12 are used, but a single controller is possible depending on the capacity of the controller.

  As described above, in video and audio devices, the buffer memory must be increased in order to eliminate interruptions in video and audio being accessed. However, this embodiment can also suppress an increase in cost.

  In addition, even for mobile applications, you will need extra memory capacity for the shock-proof memory to handle vibrations, shocks, etc., as much as the access time, but if you do not want to increase the memory to keep costs down According to this embodiment, the time for withstanding vibration and impact can be shortened.

(Second embodiment)
A flow chart of the second embodiment is shown in FIG.

  The configuration other than the flowchart is the same as that of the first embodiment.

The optical information recording / reproducing apparatus of the present embodiment, which explains the access method according to the present embodiment with reference to the flowchart of FIG. Assume that the beam is focused on the track.

  When the system controller 12 receives a reproduction command to a predetermined address from a host device (not shown), it calculates the radial distance between the current address and the target address, and determines whether it is the first layer or the second layer. .

When the radial distance and layer are known, the system controller 12 instructs the servo controller 11 on the distance, direction and target layer to be moved. (S1)
The servo controller 11 receives distance and direction information and a layer command, and first determines whether the target layer is different from the current layer. (S2)
If the layers are different, the servo controller 11 controls the track control circuit 6 and turns off the track control. (S3)
Next, the servo controller 11 controls the focus control circuit 4 to perform a focus jump by giving a focus jump pulse to the focus actuator. (S4)
After the focus jump is completed, it is determined whether the given distance (which may be during the focus jump) is a distance for moving the optical head. (S5)
When it is necessary to move the optical head, the servo controller 11 sets the number of steps to be moved, starts driving the stepping motor 8 by the driver 9, and simultaneously sets the number of movement steps of the stepping motor for generating spherical aberration to the target layer. And the driver 10 starts driving the stepping motor for generating spherical aberration. (S6)
When it is not necessary to move the optical head, the servo controller 11 sets the number of steps of the stepping motor for generating spherical aberration to the number of steps to the target layer, and the driver 10 drives the stepping motor for generating spherical aberration. Start. (S7)
The servo controller 11 confirms that the stepping motor for generating spherical aberration and the stepping motor for moving the optical head have been driven by a predetermined number of steps, and if passing through S7, only spherical aberration is sufficient. ) The track control circuit 6 is controlled to turn on the track control. (S8)
FIG. 7 shows a timing chart of each control signal from S3 through S5 to S8. Immediately after the track control is turned off (S3), a focus jump is performed. (S4) After the focus jump is finished, the optical head movement and the movement of the spherical aberration element are started (S6). Is on (S8). FIG. 7 shows an example in which the time for moving the optical head is longer than the time for moving the spherical aberration, but the reverse may occur depending on the access distance. When passing through S7, since the optical head does not move, the track control is turned on when the movement of the spherical aberration element is completed.

  In this state, the beam will be near the target track of the target layer. In order to move further to the target track, the system controller 12 reads the current address again and commands the servo controller 11 to determine the distance from the target address (S1).

  This time, since the layers are the same, only the distance will be judged.

Next, it is determined whether the distance is a distance that requires moving the optical head. (S9)
When it is necessary to move the optical head, the servo controller 11 controls the track control circuit 6 to turn off the track control, and at the same time sets the number of steps to move, drives the stepping motor 8 by the driver 9, and sets the number of target steps. Then, the track control circuit is controlled to turn on the track control. (S10)
When the distance does not require the optical head to be moved, track jump is performed by the track actuator by the number of tracks corresponding to the distance. (S11)
The above operation is repeated, and the reproduction operation is performed when the target track is reached.

  In this embodiment, when the spherical aberration generating element is operated, it is performed simultaneously with the movement of the optical head. Therefore, the spherical aberration generating element moving time of several hundreds mS and the optical head moving time similar to that are added together. And can be operated efficiently.

  In addition, since the target layer is jumped first, the spherical aberration element is moved to the optimum position in the target layer during the movement of the optical head.

  In other words, it may be possible to start from a state where the signal has deteriorated such as a tracking error. However, in this embodiment, since the optical head is moved by specifying the number of steps of the stepping motor 8, the movement operation is performed using the track count. There is no need to worry about the quality of the tracking error signal as in the case of performing.

  In addition, since the track control is not turned on until the spherical aberration element movement and the optical head movement are completed after the track control is first turned off, there is no problem even if the quality of the track error signal is deteriorated depending on the state of the spherical aberration. In addition, when the track control is finally turned on, since the spherical aberration is in an optimum state in the layer, there is no problem when the track control is turned on.

  Further, the optical head moving means may be a motor with an encoder that can recognize the moving position instead of a stepping motor. In this case, the optical head can be moved regardless of the quality of the tracking error.

  Further, in this embodiment, since the optical head movement and the spherical aberration generating element movement are performed after the focus jump, the access time is extended by the focus jump time, but there is no vibration due to the movement of the optical head, and the stable focus. You can expect a jump. Also, since the time for focus jump is usually about several milliseconds, the time does not increase greatly.

  In this embodiment, the configuration of the spherical aberration generating means is a method in which two lenses are used and one of them is driven by a stepping motor. However, this method is a method in which spherical aberration is generated by liquid crystal. May be.

  In addition, the determination of whether or not to move the optical head is simply the distance to the target track, but if the relative position between the optical head and the objective lens can be detected, the target from the center position of the optical head can be detected. It is also possible to calculate the distance to the track and make a judgment based on it.

  In this case, it is possible to make an accurate determination considering that the objective lens returns to the center when the track control is off.

  The embodiment is an example at the time of reproduction, but the case of recording is the same as the reproduction until reaching the target track.

  In the present embodiment, the two controllers of the servo controller 11 and the system controller 12 are used, but a single controller is possible depending on the capacity of the controller.

  As described above, in video and audio devices, the buffer memory must be increased in order to eliminate interruptions in video and audio being accessed. However, this embodiment can also suppress an increase in cost.

  In addition, even for mobile applications, you will need extra memory capacity for the shock-proof memory to handle vibrations, shocks, etc., as much as the access time, but if you do not want to increase the memory to keep costs down According to this embodiment, the time for withstanding vibration and impact can be shortened.

Block diagram of the first embodiment according to the present invention. Configuration of optical system including spherical aberration generating means Flow chart of the first embodiment Timing chart of the first embodiment Another example of the timing chart of the first embodiment Flow chart of the second embodiment Timing chart of the second embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk 2 Optical head 3 Error signal generation circuit 4 Focus control circuit 5 Focus driver circuit 6 Track control circuit 7 Track driver circuit 8 Optical head moving stepping motor 9, 10 Stepping motor driver 11 Servo controller 12 System controller 13 Spindle

Claims (1)

For each recording layer of an optical recording / reproducing medium having a plurality of recording layers, an objective lens for generating a focused spot with a light beam from a light source, and an optical path between the light source and the objective lens are disposed. A spherical aberration generating means for generating a spherical aberration for canceling the spherical aberration in the luminous flux in order to correct the spherical aberration generated when the condensing spot is moved to the selected recording layer; Optical information having first driving means for moving an optical head including an objective lens in the radial direction of the medium, and second driving means for moving the focused spot between the recording layers. recording in the reproduction apparatus, when accessing the focusing spot to a target address position on the current address the different from the position recording layer, the spherical aberration generating means and the first driving means Prior to driving, the second drives the driving means, the optical information recording and reproducing apparatus, wherein said driving the spherical aberration generating means during driving of the first driving means.

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