CN100373473C - Optical disk control device - Google Patents

Abstract

The invention provides an optical disk control device, which can focus and guide a target information plane of an optical disk with a plurality of information planes in a short time. An objective lens is brought close to an optical disk having a plurality of information surfaces by an output signal of a drive signal generating circuit, the passage of the initial focus position is detected by a focus point detecting circuit, when the objective lens is further brought close to the optical disk by a predetermined amount from the position, an n-turn delay circuit outputs an inversion command, and after the objective lens is changed in direction and moved away from the optical disk, a signal a output to an actuator drive circuit is switched from the drive signal generating circuit to an output signal of a control circuit, and the control circuit is started to perform focus guidance.

Description

disc control device

technical field

The present invention relates to an optical disc control device for optically recording a signal on an information carrier (optical disc) or reproducing a signal from an information carrier by using a light source such as a laser, and particularly relates to a disc control device for performing focus control, which controls the beam's Focus point for control.

Background technique

In order to optically record/reproduce information on an information carrier using a light source such as a laser, it is necessary to perform focus control so that the information surface of the information carrier is always at the focal point (focal point) of the light beam. In order to achieve this, prior to the focus control, a so-called focus guide action is carried out in which the objective lens is moved to adjust the focus position of the light beam to the information surface of the information carrier.

In addition, the existing optical disc control device realizes the miniaturization of the optical pickup (pickup) by shortening the distance between the information carrier and the objective lens, namely the so-called working distance (working distance, hereinafter referred to as WD) (for example, JP-A 5-334687 bulletin).

Hereinafter, a conventional optical disc control device will be described with reference to FIGS. 14, 15 and 16. FIG.

FIG. 14 is a block diagram showing a configuration example of a conventional optical disk control device.

In FIG. 14, the sawtooth wave signal generating circuit 45 outputs a sawtooth wave signal whose amplitude gradually increases. The switching circuit 31 switches the output signal of the sawtooth wave signal generating circuit 45 or the output signal of the control circuit 20, and sends it to the actuator (actuator) driving circuit 21 as a signal a, and the actuator driving circuit 21 makes the actuator drive according to the signal a. 22 moves, thereby driving the objective lens 23.

The focus error detection circuit 12 is a circuit that outputs a focus error signal b indicating a shift amount between the focus position of the objective lens 23 and the information surface 2A of the optical disc 2, and will be described in detail later. The focus guidance circuit 32B determines the level of the focus error signal b, and outputs the command g to the switching circuit 31, whereby the focus guidance operation is realized.

FIG. 15 is a circuit diagram showing an example of the internal configuration of the focus error detection circuit 12 shown in FIG. 14 . In FIG. 15 , the focus error detection circuit 12 uses a 4-division photodetector (4-divided photodetector) 301 in the optical pickup 3 to detect a signal corresponding to an incident beam spot 302. Two adders 1201 and 1202 generate the addition signals of (A+D) and (B+C) which are the diagonal sums of the 4-zone photodetector 301, and then use the astigmatism method (astigmatism method) to generate a focus error signal, the image In the discrete method, the subtractor 1203 generates a differential signal of (A+C)−(B+D).

Next, the focus guide operation of the conventional optical disc control device configured as above will be described with reference to FIG. 16 . FIG. 16 is a waveform diagram of signals of each part in FIG. 14 .

When the focus guide command h is output from the system controller 30 , the objective lens 23 is driven by the actuator drive circuit 21 and the actuator 22 based on the sawtooth signal output from the sawtooth signal generation circuit 45 whose amplitude varies sequentially. The amplitude of this sawtooth wave signal gradually increases, and when the focal point of the objective lens 23 reaches the information surface 2A, the focus guide circuit 32F judges the level of the focus error signal b output from the focus error detection circuit 12, and when the level reaches the guide voltage Flat timing (timing), the switching command g is output to the switching circuit 31, the signal a output to the actuator driving circuit 21 is switched from the output signal of the sawtooth wave generating circuit 45 to the output signal of the control circuit 20, and the control circuit is activated. 20, thereby performing a focus guidance operation.

Since such an optical disc control device gradually increases the amplitude of the sawtooth wave signal, it takes time until the focus error signal is detected, and as a result, the focus guide operation takes time.

In particular, when the distance between the optical disc and the objective lens increases due to surface oscillation of the optical disc or sagging of the objective lens, the time until the focus error signal is detected increases, and the time required for the focus guidance operation further increases.

In addition, when the optical disc has a plurality of information planes, it is impossible to identify which information plane the detected focus error signal belongs to, and therefore there is a problem that focus guidance cannot be performed on the target information plane.

In particular, the farther the target information plane is from the objective lens, the more focus error signals are detected, so it is difficult to guide to the target information plane.

Contents of the invention

The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical disc control device capable of performing focus guidance on a target information plane in a short time even when there are a plurality of information planes inside the optical disc.

In order to achieve the above object, the optical disc control device of the present invention has the following structure: it includes a converging irradiation device, a focus moving device, a focus error detection device, a focus point passing detection device, a reverse command device, a drive signal generation device, a control device, and a focus Guidance (focus lead-in) device.

The converging irradiation device converges and irradiates the light beam onto the information carrier with multiple information planes through the objective lens. The focus moving means moves the focus of the light beam converged by the convergent irradiation means in the normal direction of the surface of the information carrier by moving the objective lens. The focus error detection means generates a focus error signal corresponding to a positional shift of the focus of the light beam on each surface of the information carrier. The focal point passing detection device detects that the focal point of the light beam has passed the surface of the information carrier and each information plane. The inversion instruction means outputs an inversion instruction using an output signal from the focus passing detection means. The driving signal generating means outputs a signal for bringing the objective lens closer to the information carrier to the focus shifting means, and switches to a signal for moving the objective lens away from the information carrier according to the inversion command and outputs the signal. The control means uses the focus error signal to control the focus movement means such that the focus points track the respective information planes of the information carrier. The focus guide device switches the operation from the drive signal generator to the control device, and the focus guide operation is performed by the focus moving device.

According to this configuration, the objective lens can immediately enter the guiding operation without repeatedly moving up and down, and the time required for the guiding operation can be shortened. In addition, by bringing the objective lens close to the information carrier and changing the direction immediately after passing the focus point, it is possible to prevent the objective lens from approaching the information carrier unnecessarily, and to prevent the objective lens from colliding with the information carrier when the WD of the objective lens is narrow.

In addition, the optical disc control device of the present invention has a structure in which the inclination of the drive waveform is gradually changed at a switching point when the output signal from the drive signal generator moves the objective lens closer to or farther away from the information carrier.

According to this configuration, the objective lens can be prevented from vibrating due to the reaction caused by inertia, a stable focus error signal can always be obtained without generating an unstable focus error signal, and stability can also be ensured in the focus guidance operation.

In addition, the optical disk control device of the present invention has a structure in which an aberration setting corresponding to a target information plane is performed on an information carrier having a plurality of information planes, and the target information plane is discriminated based on the amplitude value of the focus error signal. At this time, it is preferable to detect the phase relationship between the focus error signal and the reflected light amount signal based on the maximum value of the level of the reflected light amount signal and the level of the reflected light amount signal when the focus error signal is extremely large and extremely small, thereby discriminating the target information. noodle.

According to this structure, the focus error signal of the target information plane can be correctly discriminated from among the plurality of focus error signals obtained from a plurality of focus error signals having a plurality of information The surface information carrier is detected.

In addition, the optical disk control device of the present invention has the following structure: when the objective lens is made close to the information carrier having a plurality of information planes, and when the passage of the initial focal point position is detected, the objective lens is further approached by a predetermined amount from the position to the information carrier. , after changing the direction to keep the objective lens away from the information carrier, the focus guiding device performs a focus guiding action.

According to this configuration, the objective lens can be prevented from approaching the information carrier unnecessarily by making the objective lens approach the information carrier only by a predetermined amount from the initial focus point, and collision between the objective lens and the information carrier can be prevented even when the WD is narrow. In addition, it is not necessary to judge whether the information plane is the target plane for an information carrier having a plurality of information planes, so that misleading caused by wrong judgment and collision between the objective lens and the information carrier can be avoided. In addition, even without discriminating the information plane, it is possible to guide the focus on the target information plane by adjusting the movement amount of the objective lens, that is, the predetermined amount.

In addition, the optical disc control device of the present invention has a structure for discriminating the target information plane by detecting the focal position of the light beam in accordance with the order in which the maximum and minimum values of the focus error signal appear on an information carrier having a plurality of information planes.

According to this structure, the focus error signal of the target information plane can be correctly discriminated from among the plurality of focus error signals, which have multiple The information carrier of the information surface is detected.

In addition, the optical disc control device of the present invention has the following structure: comprising a plane discrimination device, for an information carrier having a plurality of information planes, it is judged that the plane detected by the focal point passing detection device is a predetermined plane contained in the information carrier; device, based on the output signal from the surface discrimination device to set the amount of movement of the objective lens; the amount of movement management detection device B detects that the focus point passes through the focus point after the focus point is detected by the detection device. Amount B is managed and detected; and reverse instruction means outputs a reverse instruction using an output signal from the movement amount management detection means.

According to this structure, the plane discriminated by the plane discriminating means can be determined to be the information plane contained in the information carrier, and since the determined information plane is moved to the target information plane, the reliability and promptness of focus guidance can be achieved.

Description of drawings

FIG. 1 is a block diagram showing an example configuration of an optical disc control device according to Embodiment 1 of the present invention.

FIG. 2 is a waveform diagram of signals of various parts of the optical disc control device in FIG. 1 .

FIG. 3A is a diagram showing the shape of the beam spot 302 on the four-zone photodetector 301 at each point of the S-shaped waveform of the focus error signal b in FIG. 1 when there is no spherical aberration.

3B is a diagram showing the shape of the beam spot 302 on the four-zone photodetector 301 at each point of the S-shaped waveform of the focus error signal b in FIG. 1 when spherical aberration is present.

4 is a block diagram showing an example configuration of an optical disc control device according to Embodiment 2 of the present invention.

FIG. 5 is a waveform diagram of signals of various parts in FIG. 4 when the rotational speed of the optical disk is relatively fast.

FIG. 6 is a waveform diagram of signals of various parts in FIG. 4 when the rotational speed of the optical disk is relatively slow.

7 is a block diagram showing an example configuration of an optical disc control device according to Embodiment 3 of the present invention.

8A is a diagram illustrating the relationship between the S-shaped waveform of the focus error signal b of FIG. 7 and the reflected light amount signal c when there is no spherical aberration.

8B is a diagram illustrating the relationship between the S-shaped waveform of the focus error signal b of FIG. 7 and the reflected light amount signal c when spherical aberration is present.

FIG. 9 is a waveform diagram of signals of various parts of the optical disc control device in FIG. 7 (for example, when the rotational speed of the optical disc is relatively fast, etc.).

FIG. 10 is a block diagram showing an example configuration of an optical disk control device according to Embodiment 4 of the present invention.

FIG. 11 is a waveform diagram of signals of various parts of the optical disk control device of FIG. 10. FIG.

FIG. 12 is a block diagram showing a configuration example of an optical disk control device according to Embodiment 5 of the present invention.

Fig. 13 is a waveform diagram of the signals of each part of Fig. 12 when the optical disc is wobbled.

FIG. 14 is a block diagram showing a configuration example of a conventional optical disk control device.

FIG. 15 is a circuit diagram showing the internal configuration of the focus error detection circuit 12 shown in FIG. 14 .

FIG. 16 is a waveform diagram of signals of various parts of the optical disk control device of FIG. 14. FIG.

Detailed ways

Preferred embodiments of the present invention will be described in detail below with reference to the drawings.

(Embodiment 1)

FIG. 1 is a block diagram showing an example configuration of an optical disc control device according to Embodiment 1 of the present invention. In FIG. 1 , the same reference numerals are assigned to the same components as those in the conventional example, and description thereof will be omitted.

In FIG. 1 , a disk 1 is a two-layer laminated disk having a first information surface 1A and a second information surface 1B. The aberration setter 63 outputs an aberration setting value that does not cause spherical aberration to the light beam to the information plane designated by the system controller 30 . The aberration adjuster 65 adjusts the spherical aberration of the beam focus via the aberration adjuster drive circuit 64 according to the set value of the aberration setter 63 .

The reflected light amount detection circuit 41 outputs a signal (hereinafter referred to as a reflected light amount signal) c proportional to the amount of light reflected from the disc 1 . The focus point passes through the detection means 44 to identify the S-shaped waveform of the focus error signal b output from the focus error detection circuit 12 under the condition that the reflected light amount signal c from the reflected light amount detection circuit 41 is greater than or equal to the predetermined value Clv1, and the reflected light amount signal c On the condition that c is smaller than the predetermined value Clv1, it is detected that the focal point has passed.

The amplitude detection circuit 62 detects the amplitude of the S-shaped waveform of the focus error detection signal b based on the focus error signal b and the focus pass signal d output from the focus pass detection circuit 44 . The information surface detection circuit 61 detects that the information surface of the target to be guided has passed if the amplitude value output from the amplitude detection circuit 62 is greater than a predetermined value Bcmp when the signal from the focus point passage detection circuit 44 is output.

The characteristic correction circuit 43 sets the gain of the control circuit 20 according to the ratio between the amplitude value b1A of the S-shaped waveform output from the amplitude detection circuit 62 and the reference value Bstd when the information plane detection circuit 61 detects that it is the target information plane. Make corrections.

If the information surface detection circuit 61 detects that the target information surface has passed, the inversion instruction circuit 40 outputs an inversion instruction f to the focus guide circuit 32A and the drive signal generation circuit 42A. When the drive signal generation circuit 42A outputs a signal to make the objective lens 23 approach or move away from the disk 1, the inclination of the drive waveform does not change sharply, and the inclination of the drive waveform is gradually changed. When the system controller 30 starts h , for a certain period of time, the objective lens 23 outputs a driving signal that moves the objective lens 23 away from the disk 1 at first, and then changes direction to output a driving signal that moves closer to the disk 1 . The focus guidance circuit 32A, under the condition that the inversion instruction circuit 40 outputs the inversion instruction f and is already in the inversion state, judges the level of the focus error signal b, and outputs an instruction g to the switching circuit 31, thereby realizing focusing Bootstrap action.

Next, the operation of the disk control device configured as above will be described with reference to FIGS. 1 , 2 and 3 .

FIG. 2 is a waveform diagram of signals of various parts of the optical disc control device in FIG. 1 . The system controller 30 sends the focus guide command h and the information on the target information plane (the first information plane 1A in this embodiment) to the drive signal generation circuit 42A and the aberration setter 63, respectively. The aberration setter 63 adjusts the aberration adjuster 65 so that spherical aberration does not occur on the designated first information plane 1A. At the same time, the drive signal generation circuit 42A outputs a drive signal in a direction that moves the objective lens 23 away from the disc 1 so that the inclination of the drive waveform does not change abruptly. The driving signal generation circuit 42A switches to a driving signal in a direction in which the objective lens 23 approaches the disk 1 after moving the objective lens 23 away from the disk 1 by a predetermined amount so that the inclination of the driving waveform does not change abruptly. When the objective lens 23 approaches the disk 1, its focus point passes through the second information plane 1B, and the S-shaped waveform b1 in which the focus point passes through the second information plane 1B is output from the focus error detection circuit 12 .

Here, the S-shaped waveform when spherical aberration does not occur and the S-shaped waveform when spherical aberration occurs will be described with reference to FIGS. 3A and 3B . 3A and 3B are diagrams showing the shapes of the beam spot 302 on the four-zone photodetector 301 at each point of the S-shaped waveform when spherical aberration does not occur and when spherical aberration occurs, respectively.

As shown in FIG. 3A , when no spherical aberration occurs, the beam spot 302 is in the shape of a thin line at the peaks and valleys of the S-shaped waveform. On the other hand, as shown in FIG. 3B , when spherical aberration occurs, the central portion and the peripheral portion of the objective lens 23 have different ways of concentrating light beams, so that the light intensity in the beam spot differs (beam spot 302a in the central portion , the beam spot 302b on the outer periphery). Also, the shape of the beam spots at the peaks and valleys of the S-shaped waveform is not a thin line. Therefore, the absolute values of the peaks and valleys of the S-shaped waveform become smaller, and the amplitude of the S-shaped waveform becomes smaller.

In this way, the amplitude value (b1B) of the S-shaped waveform b1 of the second information plane 1B whose amplitude becomes smaller due to the occurrence of spherical aberration is compared with the predetermined value (Bcmp) input to the information plane detection circuit 61 to determine Because it is not the target information surface. When the objective lens 23 gets closer to the disc 1, its focal point passes through the first information plane 1A, and the S-shaped waveform b2 in which the focal point passes through the first information plane 1A is output from the focus error detection circuit 12. The information surface detection circuit 61 judges that the S-shaped waveform is the target when the amplitude (b1A) of the S-shaped waveform b2 detected at the timing of the focus passing signal d is greater than a predetermined value (Bcmp) as in the case of the second information surface 1B. The waveform of the information plane.

When the information surface detection circuit 61 detects the target information surface (the first information surface 1A in this embodiment), the inversion command circuit 40 outputs the inversion command f to the focus guide circuit 32A and the drive signal generation circuit 42A. Drive signal generation circuit 42A receives the inversion command, and switches to a drive signal in a direction in which objective lens 23 is separated from disk 1 so that the inclination of the drive waveform does not change abruptly. At the same time, when the information plane is detected, the characteristic correction circuit 43 compares the amplitude value (b1A) of the S-shaped waveform b2 output from the amplitude detection circuit 62 with respect to the first information plane 1A with the reference amplitude value (Bstd), and performs This ratio performs gain adjustment of the control circuit 20 so that the control gain after focus guidance becomes appropriate. Simultaneously, the focus guidance circuit 32A that has received the inversion command f is in a state where a guidance operation based on the level determination of the focus error signal b can be performed.

When the objective lens 23 moves away from the disc 1 and the S-shaped waveform b3 is output from the focus error detection circuit 12, the focus guide circuit 32A judges the level of the focus error signal b (b3), and the level reaches the guide level. The switching command g is output to the switching circuit 31 at the timing of , the signal a output to the actuator driving circuit 21 is switched from the output signal of the driving signal generating circuit 42A to the output signal of the control circuit 20, and the focus guidance is performed by starting the control circuit 20 action.

As described above, according to the present embodiment, the output signal from the driving signal generating circuit 42 causes the objective lens 23 to move away from the disk 1 by a predetermined amount, then changes direction and approaches the disk 1, and when it is detected from the focus error signal that the focus point position passes the target information surface When driving, the direction is changed immediately away from the disc 1, and then the focusing error signal generated is used to perform the focus guide action, so that the objective lens 23 can immediately enter the guide action without repeatedly performing up and down movements, and the time required for the guide action can be shortened. time. Furthermore, by bringing the objective lens 23 close to the disc 1 and changing its direction immediately after passing the focal point, it is possible to prevent the objective lens 23 from approaching the disc 1 unnecessarily, and to prevent the objective lens 23 from colliding with the disc 1 even when the WD is narrow.

When the S-shaped waveform on the target information surface is detected, the characteristic correction circuit 43 optimizes the gain of the control circuit 20 according to the amplitude, so that only learning the S amplitude can further shorten the time of the focus guidance operation, and there is no need to drive Objective lens 23.

In addition, the focus point passage detection circuit 44 uses the reflected light amount signal from the reflected light detection circuit 41 together with the focus error signal in order to detect the passage of the focus point position, thereby removing the noise of the focus error signal and performing reliable focus point detection. This can realize a stable focus guide operation.

In addition, when the output signal of the driving signal generating circuit 42A changes the moving direction of the objective lens 23, the inclination of the driving waveform is gradually changed so that the inclination of the driving waveform does not change abruptly, thereby preventing the objective lens 23 from vibrating and causing no malfunction. The stable focus error signal can reliably realize the focus guidance operation with the stable focus error signal.

In addition, by using the aberration adjuster 65 to control the aberration of the light beam for a disc 1 having a plurality of information surfaces, and setting the light beam so that spherical aberration does not occur on the target information surface, it is possible to obtain a signal based on the S-shape of the focus error signal b. The amplitude of the signal determines the target information plane, and it is possible to discriminate the target information plane for the disc 1 having a plurality of information planes with a simple structure, and reliably perform focus guidance on the information plane.

In this embodiment, the driving signal generation circuit 42 drives so that the objective lens 23 is initially separated from the disk 1, but this embodiment is not limited to, and the position of the objective lens 23 at the beginning and the magnitude of the surface wobble of the disk 1 may also be used. Driving is performed so that the objective lens 23 approaches the disk 1 at once.

(Embodiment 2)

4 is a block diagram showing an example configuration of an optical disc control device according to Embodiment 2 of the present invention. In FIG. 4 , the same reference numerals are assigned to the same components as those in the conventional example and Embodiment 1, and description thereof will be omitted.

In Fig. 4, after the constant calculation circuit 71 and the focus point pass the detection circuit 44 to detect the initial S-shaped waveform, the object lens 23 will be close to the distance L of the optical disc 1 and the rotating speed Vrot of the disc motor 24, using the following formula (1 ) and Equation (2) calculate the number n of waiting rotations set in the n-rotation delay circuit 70 and the drive speed Vlns of the objective lens 23 set in the drive signal generating circuit 42A.

n=K×L×Vrot …(1)

Vlns＝(L×Vrot)/n ...(2)

In the above formula (2), K is a constant for converging the driving speed Vlns within a certain range.

In particular, the result of the formula (1) is rounded to an integer to obtain the number n of waiting rotations. Here, as the predetermined distance L, a distance that must be moved by the objective lens 23 in order to at least move the focus of the objective lens 23 from the surface 1C to the first information surface 1A is ensured.

The n-turn delay circuit 70 outputs an inversion instruction f to the drive signal generating circuit 42A after the optical disc 1 rotates n turns from the zero-crossing point of the first S-shaped waveform based on the focus error signal b and the focus pass signal d. The driving signal generating circuit 42B outputs a signal for moving the objective lens 23 away from or approaching the optical disc 1, and at least the speed at which the objective lens 23 approaches the optical disc 1 is set by the calculation circuit 71 described above. The focus guide circuit 32B judges the level of the focus error signal b under the condition that the n-rotation delay circuit 70 outputs the reverse command f and is already in the reverse state, and outputs the command g to the switching circuit 31 according to the judgment result, thereby Implement focus-guided actions.

Next, the operation of the optical disk control device configured as above will be described with reference to FIGS. 4 , 5 and 6 .

FIG. 5 is a waveform diagram of signals of various parts in FIG. 4 when the rotational speed Vrot of the optical disc 1 is relatively fast.

First, a focus guide command h is sent from the system controller 30 to the drive signal generation circuit 42B. Simultaneously, constant calculating circuit 71, with the rotating speed Vrot of optical disc 1 at this moment, use above-mentioned formula (1) and formula (2) to calculate the speed Vlns of waiting revolution n (=3) and object lens 23, in n turns delay circuit 70 and drive signal generating circuit 42B are set separately.

The drive signal generation circuit 42B outputs a drive signal so that the objective lens 23 approaches the optical disc 1 at the drive speed Vlns set by the constant calculation circuit 71 . When the objective lens 23 approaches the optical disc 1, its focal point passes through the surface 1C of the optical disc 1, and the resulting S-shaped waveform is output from the focus error detection circuit 12 (b1). The n-turn delay circuit 70 takes the zero-crossing point of the first S-shaped waveform b1 as a starting point, and outputs the S-shaped waveform b2 to the 2nd information plane 1B, the S-shaped waveform b2 to the 1st information plane 1 during the time when the optical disk 1 rotates 3 revolutions. After the S-shaped waveform b3) of surface 1A, the inversion command f is output. This corresponds to the timing at which the objective lens 23 approaches the optical disc 1 by a predetermined distance L after the first S-shaped waveform b1 is detected.

The inversion command f output from the n-rotation delay circuit 70 is input to the focus guide circuit 32B and the drive signal generation circuit 42B. The drive signal generation circuit 42B switches to a drive signal in a direction in which the objective lens 23 is separated from the optical disc 1 in response to the inversion command. Simultaneously, the focus guide circuit 32B having received the inversion command f is in a state where the guide operation based on the level determination of the focus error signal b can be performed.

In addition, when the objective lens 23 moves away from the optical disc 1 and the S-shaped waveform (b4) is output from the focus error detection circuit 12, the focus guide circuit 32B judges the level of the focus error signal b, and the level reaches the guide level The switching command g is output to the switching circuit 31 at the timing, the signal a output to the actuator driving circuit 21 is switched from the output signal of the driving signal generating circuit 42B to the output signal of the control circuit 20, and by starting the control circuit 20, the control circuit 20 is activated. Focus guidance operation of the first information plane 1A.

FIG. 6 is a waveform diagram of signals in various parts of FIG. 4 when the rotational speed Vrot of the optical disc 1 is relatively low.

The basic operation of guiding the focus guidance command h from the system controller 30 is the same as when the rotational speed Vrot of the optical disc 1 is relatively fast, but the rotational speed Vrot of the optical disc 1 is slow, so the number of waiting rotations n changes from 3 to 2, And set the corresponding speed Vlns of the objective lens 23. Even at this time, the output of the inversion command f corresponds to the timing at which the objective lens 23 approaches the optical disc 1 by a predetermined distance L after the first S-shaped waveform b1 is detected.

As described above, in the present embodiment, the constant calculation circuit 71 calculates in the n-rotation delay circuit 70 based on the rotational speed Vrot of the optical disc 1 and the distance L for the objective lens 23 to approach the optical disc 1 after the initial S-shaped waveform b1 is detected. The set rotation waiting number n and the drive speed Vlns of the objective lens 23 are set in the drive signal generation circuit 42B. As a result, the objective lens 23 can immediately enter the guiding operation without repeatedly moving up and down, so the time required for the guiding operation can be shortened. In addition, the objective lens 23 is made close to the optical disc 1, and the direction of the objective lens 23 is changed when the optical disc 1 has only approached the predetermined distance L from the initial S-shaped waveform b1, thereby, the objective lens 23 does not need to approach the optical disc 1 unnecessarily, and the WD Even when it is narrow, it is possible to prevent the objective lens 23 from colliding with the optical disc 1 .

In addition, by changing the direction of the objective lens 23, the timing of starting the determination of the level of the focus error signal b for guidance is n rotations (n is an integer) after the optical disc 1 rotates from the zero crossing of the first S-shaped waveform b1. Even when the optical disc 1 has a surface wobble component, when the level determination of the focus error signal b is started, the focus can be ensured to be inside the first information plane 1A, and the focus guidance to the information plane 1A can be reliably performed.

In addition, by calculating the waiting number of revolutions n and the lens moving speed Vlns from the rotating speed Vrot of the optical disc 1, the lens moving speed Vlns is kept substantially constant even if the rotating speed Vrot of the optical disc 1 is different, thereby ensuring stability during focus guidance. sex. In addition, the amount of movement of the objective lens 23 from the detection of the initial S-shaped waveform to n rotations of the optical disc 1 can always be kept at a predetermined distance L, thereby preventing the objective lens 23 from approaching the optical disc 1 unnecessarily. In addition, since the objective lens 23 can be driven without stopping, the speed switching point can be reduced, and the adverse effect caused by the shaking of the objective lens 23 can be suppressed to a minimum.

Furthermore, when the focus point passage detection circuit 44 detects the passage of the focus point position, by using the focus error signal b and the reflected light amount signal c from the reflected light amount detection circuit 41, the noise of the focus error signal b is removed, and reliable focus point detection is performed. , thereby achieving stable focus guidance.

In the present embodiment, the driving signal generation circuit 42B is described as a circuit that drives the objective lens 23 in the direction in which it approaches the optical disc 1 from the beginning. However, the present invention is not limited thereto, and it is also possible to drive the objective lens 23 away from the optical disc 1 by a predetermined distance at first in consideration of the surface wobble of the optical disc 1, and then change direction and drive so as to approach the optical disc 1.

In addition, as a method of maintaining the movement amount of the objective lens 23 at the predetermined distance L, the following configuration may be employed, and the invention is not limited to this embodiment. That is, the lens moving speed Vlns is made constant regardless of the rotational speed Vrot of the optical disc 1. After the objective lens 23 moves only a predetermined distance L, before the optical disc 1 rotates n revolutions, it stops at this position. After disc 1 rotates n times, change direction. Likewise, the waiting number n of rotations can be set regardless of the rotation speed Vrot, and is not limited to this embodiment.

(Embodiment 3)

7 is a block diagram showing an example configuration of an optical disc control device according to Embodiment 3 of the present invention. In FIG. 7 , the same reference numerals are assigned to the same constituent elements as those in the conventional example, Embodiment 1, and Embodiment 2, and description thereof will be omitted.

In FIG. 7, the maximum value/and minimum value detection circuit 80 detects the focus error signal b from the focus error detection circuit 12 under the condition that the reflected light quantity signal c from the reflected light quantity detection circuit 41 is greater than or equal to a predetermined value Clv1 maximum and minimum values of . The reflected light amount difference detection circuit 81 detects the level difference ΔV of the reflected light amount signal c from the reflected light amount detection circuit 41 at respective timings when the local maximum value/minimum value detection circuit 80 detects a local maximum value and a local minimum value. The maximum value detection circuit 82 always detects in advance the maximum value of the reflected light amount signal c from the reflected light amount detection circuit 41, determines the maximum value at the timing when the focus point passing detection signal d is output from the focus point passing detection circuit 44, and converts the The maximum value information is sent to a normalizing circuit (normalizing circuit) 83 . The positive normalization circuit 83 performs positive normalization by dividing the maximum value Vmax from the maximum value detection circuit 82 by the level difference ΔV of the reflected light amount from the reflected light amount difference detection circuit 81 . The information plane discrimination circuit 84 discriminates whether or not it corresponds to the target information plane by comparing the positively normalized reflected light amount difference from the positive normalization circuit 83 with a predetermined value Ncmp. The inversion command circuit 40 outputs the inversion command f at the timing of which of the output signal from the n-rotation delay circuit 70 and the output signal from the information surface discrimination circuit 84 is earlier, and sends it to the focus guide circuit 32C and the drive circuit 32C. Signal generating circuit 42C.

Next, the operation of the optical disc control device configured as described above will be described with reference to FIGS. 7 , 8 and 9 .

8A and 8B are diagrams illustrating the relationship between the S-shaped waveform of the focus error signal b and the reflected light amount signal c when there is no spherical aberration and when there is spherical aberration, respectively. FIG. 9 is a waveform diagram of signals of various parts of the optical disc control device in FIG. 7 (for example, when the rotational speed Vrot of the optical disc 1 is relatively fast, etc.).

In FIG. 9 , first, the focus guide command h is sent from the system controller 30 to the drive signal generating circuit 42C. The aberration setter 63 adjusts the aberration by the aberration adjuster 65 via the aberration adjuster drive circuit 64 so that spherical aberration does not occur on the designated first information plane 1A. Also, the driving signal generation circuit 42C outputs a driving signal for causing the objective lens 23 to approach the optical disc 1 at a lens moving speed Vlns obtained by using the equation (1) and the equation described in Embodiment 2 by the constant calculation circuit 71. (2) Calculated. When the objective lens 23 approaches the optical disk 1, its focal point passes through the surface 1C and the second information surface 1B, and the resulting waveforms b1 and b2 are output from the focus error detection circuit 12.

Here, the S-shaped waveform when no spherical aberration occurs and the S-shaped waveform when spherical aberration occurs will be described with reference to FIGS. 8A and 8B .

Fig. 8 A shows the shape of the beam spots 302 on the 4-zone photodetector 301 of each point of the S-shaped waveform when no spherical aberration is produced. Points 302 are thin lines. FIG. 8B shows the shape of beam spots on the four-zone photodetector 301 at each point of the S-shaped waveform when spherical aberration occurs. When spherical aberration occurs, since the concentrating mode of the light beams on the inner peripheral side and the outer peripheral side of the objective lens 23 is different, the light intensity in the beam spot will deviate (beam spot 302a on the inner peripheral side, beam spot 302a on the outer peripheral side) 302b). Also, the shape of the beam spots at the peaks and valleys of the S-shaped waveform is not a thin line. Especially when the 4-zone photodetector 301 is reduced, the beam spot will overflow from the 4-zone photodetector 301 at the trough (or peak) of the S-shaped waveform. On the other hand, on the peak (or trough) side of the S-shaped waveform, there is no overflow from the four-zone photodetector 301 even at a position farther from the zero cross point. That is, the S-shaped waveform of the focus error signal b and the convexity of the reflected light amount signal c are out of phase.

In this way, the phases of the S-shaped waveform and the reflected light amount signal c are shifted between the surface 1C and the second information surface 1B on which spherical aberration has occurred. The maximum value/minimum value detection circuit 80 ( FIG. 7 ) detects the timing of the peaks and valleys of these S-shaped waveforms, and the reflected light amount difference detection circuit 81 calculates the voltage of the reflected light amount signal from the reflected light amount detection circuit 41 at the respective timings. Adjustment ΔV. When the focus point passing detection circuit 44 detects the passage of the S-shape waveform, the maximum value detection circuit 82 determines the maximum value Vmax and sends it to the positive normalization circuit 83 . The positive normalization circuit 83 uses ΔV and Vmax to calculate the positive normalization data N (=ΔV/Vmax), and the information surface discrimination circuit 84 compares the positive normalization data N (N2 in FIG. 8B ) with a predetermined value Ncmp. Since N2≥Ncmp , so it is determined that the S-shaped waveform does not correspond to the target first information plane 1A.

In addition, as shown in FIG. 9 , when the objective lens 23 gets closer to the optical disc 1 , its focal point passes through the first information plane 1A, and the resulting S-shaped waveform b3 is output from the focus error detection circuit 12 . Same as the case of the surface 1C and the second information surface 1B, the maximum value/minimum value detection circuit 80, the reflected light amount difference detection circuit 81 and the maximum value detection circuit 82 operate, and the information surface discrimination circuit 84 receives the information from the positive normalization circuit 83. The positively normalized data N (N1 in FIG. 8A ) is compared with the predetermined value Ncmp, and N1<Vcmp, so it is determined that the S-shaped waveform corresponds to the target information plane 1A.

When the information surface discrimination circuit 84 detects that the target first information surface 1A is sent to the inversion instruction circuit 40, the inversion instruction from the n-turn delay circuit 70 has not yet arrived, and the inversion instruction circuit 40 will The inversion instruction f1 is output to the focus guide circuit 32C and the drive signal generation circuit 42C. The drive signal generating circuit 42C receives the inversion command f1 and switches to a drive signal in a direction in which the objective lens 23 is separated from the optical disc 1 . At the same time, the focus guide circuit 32C having received the inversion command f1 is in a state capable of performing the focus guide operation based on the level determination of the focus error signal b.

In addition, when the objective lens 23 moves away from the optical disc 1, when the S-shaped waveform b4 is output from the focus error detection circuit 12, the focus guide circuit 32C judges the level of the focus error signal b, and when the level reaches the guide level, At the timing, the switching command g1 is output to the switching circuit 31, the signal a output to the actuator driving circuit 21 is switched from the driving signal generating circuit 42C to the output signal of the control circuit 20, and the control circuit 20 is activated, thereby performing the focus guidance operation. .

On the other hand, in this embodiment, as in Embodiment 2, there is an n-rotation delay circuit 70, and the n-rotation delay circuit 70 is set to be calculated by the constant calculation circuit 71 based on the rotational speed Vrot of the optical disc 1 using equation (1). The detected waiting number n of rotations provides an output signal to the inversion command circuit 40 after a time delay of n rotations of the optical disk 1 from the zero crossing of the first detected S-shaped waveform b1. The inversion command circuit 40 ignores the input from the n-turn delay circuit 70 when the information plane discrimination in the information plane discrimination circuit 84 is properly operated and the inversion command has already been input. However, when the information plane discrimination in the information plane discrimination circuit 84 cannot properly operate due to noise contained in the reflected light amount signal c, etc., and the inversion command is not input, the input signal from the n-rotation delay circuit 70 is used to Output reverse instruction f2. Subsequent operations are the same as those in Embodiment 2, so descriptions are omitted.

As described above, in the present embodiment, the output signal of the driving signal generating circuit 42C causes the objective lens 23 to approach the optical disc 1, calculates the level difference of the reflected light amount signal at the timing of the peak and valley of the focus error signal b, and calculates the level difference of the reflected light amount signal by using the reflected light amount The maximum value of the positively normalized value is compared with the predetermined value to detect the target information surface. When the target information surface is detected, the direction is changed immediately, and the objective lens 23 is driven away from the optical disc 1, and then the focus guide operation is performed using the generated focus error signal. As a result, the objective lens 23 can immediately enter the guiding operation without repeatedly moving up and down, so the time required for the focus guiding operation can be shortened. In addition, since the objective lens 23 is made close to the optical disc 1, and the direction is changed immediately after the target information surface is detected, it is also possible to prevent the objective lens 23 from colliding with the optical disc 1 when the WD is narrow, and the objective lens 23 does not need to approach the optical disc 1 unnecessarily. .

In addition, when the focus point passage detection circuit 44 detects the passage of the focus point position, by using the focus error signal b and the reflected light amount signal c from the reflected light amount detection circuit 41, the noise of the focus error signal b is removed, and reliable focus point detection is performed. , thereby achieving stable focus guidance.

In addition, even if there is noise in the reflected light amount signal c, the normalized data N obtained by normalizing the level difference of the reflected light amount signal with the maximum value of the reflected light amount is scattered, and the information plane discrimination circuit 84 fails to discriminate the information plane. In the case of , the n-rotation delay circuit 70 is also used to output an inversion command. Therefore, the focus guide operation can be performed reliably, and the objective lens 23 can be prevented from colliding with the optical disc 1, and a highly reliable optical disc control device can be realized.

In addition, when the information surface discrimination fails, the timing of changing the direction of the objective lens 23 and starting the level determination of the focus error signal b for guidance is after the optical disc 1 rotates n times from the zero crossing of the initial S-shaped waveform. (n is an integer), thus, even when the optical disc 1 has a surface wobble component, it can be ensured that the focal point is always behind the information surface 1A when the level determination of the focus error signal b is started. In this way, the focus guidance operation on the first information plane 1A can be reliably performed without failure.

In addition, by calculating the waiting rotation number n and the lens moving speed Vlns from the rotating speed Vrot of the optical disc 1, the lens moving speed Vlns is kept substantially constant even if the rotating speed Vrot of the optical disc 1 is different, thereby ensuring stability during focus guidance. And, under the situation that the information plane discriminates and fails, also can object lens 23 detect from initial S-shaped waveform to the amount of movement after optical disk 1 rotates n turns always keep as predetermined distance L, can avoid object lens 23 needlessly approaching Disc 1.

In the present embodiment, the driving signal generation circuit 42C is described as a circuit that drives the objective lens 23 from the initial direction toward the optical disc 1 . However, the present invention is not limited thereto, and it is also possible to drive the objective lens 23 away from the optical disc 1 by a predetermined distance L in consideration of the surface wobble of the optical disc 1, and then change direction and drive so as to approach the optical disc 1.

As a method of maintaining the movement amount of the objective lens 23 at the predetermined distance L, the following configuration may be adopted, and the invention is not limited to this embodiment. That is, the lens moving speed Vlns is made constant regardless of the rotational speed Vrot of the optical disc 1. After the objective lens 23 only moves a predetermined distance L, it stops at this position after the optical disc 1 rotates n revolutions. 1 to change direction after n turns. Similarly, the waiting rotation number n for rotation may be set independently of the rotation speed Vrot, and is not limited to this embodiment.

(Embodiment 4)

FIG. 10 is a block diagram showing an example configuration of an optical disc control device according to Embodiment 3 of the present invention. In FIG. 10 , the same reference numerals are assigned to the same constituent elements as those of the conventional example, Embodiment 1, Embodiment 2, and Embodiment 3, and description thereof will be omitted.

In Fig. 10, the information surface discriminating circuit 84A judges that its S-shaped waveform is an S-shaped waveform other than the surface 1C according to the normalized reflected light amount difference output by the positive normalization circuit 83, that is, the first information surface 1A or the first information surface 1A. The S-shaped waveform of information plane 1B. That is, in this embodiment, since the accuracy of information plane discrimination is assumed to be lower than that of the information plane discrimination circuit 84 in Embodiment 3, the second information plane 1B and the first information plane 1A may not be correctly distinguished.

The constant calculation circuit 71A calculates the distance L, the waiting number of rotations n, and the drive speed by using the above-mentioned equations (1) and (2) as in the third embodiment until the information surface discrimination circuit 84A detects an S-shaped waveform other than the surface 1C. Vlns, and when the information surface discriminating circuit 84A detects the S-shaped waveform other than the surface 1C, the object lens 23 will be close to the distance S of the optical disc 1 after the S-shaped waveform of the second information surface 1B is detected, the rotating speed Vrot of the disc motor 24, The number of waiting rotations m set in the m-rotation delay circuit 72 described later and the drive speed Vlns2 of the objective lens 23 set in the drive signal generating circuit 42D are calculated by the following equations (3) and (4).

m=K×S×Vrot …(3)

Vlns2＝(S×Vrot)/m

Here, as the predetermined distance S, a distance that must be moved by the objective lens 23 in order to at least move the focus of the objective lens 23 from the second information plane 1B to the first information plane 1A is ensured. The relationship between L and S is L>S, and the difference between L and S is larger than the distance from the surface 1C to the second information surface 1B when the predetermined amount is reliably moved including individual variation.

The m-rotation delay circuit 72 is based on the output signal from the information plane discrimination circuit 84A and the output signal from the focus point passing detection circuit 44, from the zero cross point of the S-shaped waveform of the first information plane 1A or the second information plane 1B to the optical disc 1. After m rotations, a signal is output to the inversion instruction circuit 40A.

The inversion instruction circuit 40A outputs the inversion instruction f at the timing of whichever output signal is earlier among the output signal from the n-turn delay circuit 70 and the output signal from the m-turn delay circuit 72, and sends it to the pilot circuit 32A and the drive signal generation Circuit 42D.

Next, the operation of the optical disk control device configured as above will be described with reference to FIG. 11 . FIG. 11 is a waveform diagram of signals of various parts of the optical disk control device of FIG. 10. FIG.

In FIG. 11, a focus guide command h is sent from the system controller 30 to the drive signal generating circuit 42D. The aberration setter 63 adjusts the aberration adjuster 65 so that spherical aberration does not occur on the designated first information plane 1A. The driving signal generating circuit 42D outputs a driving signal in a direction in which the objective lens 23 approaches the optical disc 1 at the lens moving speed Vlns calculated from the equations (1) and (2) by the constant calculating circuit 71A. When the objective lens 23 approaches the optical disk 1, its focus passes through the surface 1C and the second information surface 1B, and the resulting S-shaped waveforms b1 and b2 are output from the focus error detection circuit 12.

The maximum value/minimum value detection circuit 80 outputs the timing of the peaks and valleys of these S-shaped waveforms b1, b2, and the reflected light amount difference detection circuit 81 calculates the difference ΔV of the output value of the reflected light amount detection circuit 41 at this timing. When the focus point passing detection circuit 44 detects the passage of the S-shape waveform, the maximum value detection circuit 82 determines the maximum value Vmax and sends it to the positive normalization circuit 83 . The positive normalization circuit 83 uses ΔV and Vmax to calculate the positive normalization data N (=ΔV/Vmax), compares the positive normalization data N with the predetermined value Ncmp through the information surface discrimination circuit 84A, and judges it as the second S-shaped waveform b2 Not the waveform of Surface 1C. At this time, as indicated by the arrow AR, if the information plane can be discriminated, the rotational phase signal of the disk motor 24 coincides with the discriminated zero-cross point of the S-shaped waveform b2.

The constant calculation circuit 71A calculates the waiting rotation number m=1 and the speed Vlns2 of the objective lens 23 according to the rotation speed Vrot of the optical disc 1 at this time using the above-mentioned formula (3) and formula (4), and turns the delay circuit in the drive signal generation circuit 42D and m. 72 to set. The drive signal generation circuit 42D outputs a drive signal so that the objective lens approaches the optical disc 1 at the drive speed Vlns2 calculated by the constant calculation circuit 71A. The m-rotation delay circuit 72 outputs a signal to the inversion command circuit 40A after the optical disk 1 rotates one revolution starting from the zero-crossing point of the S-shaped waveform b2 of the second information plane 1B. This corresponds to the timing at which the objective lens 23 approaches the optical disc 1 by a predetermined distance S after the second S-shaped waveform b2 is detected.

Since the output signal of the m-turn delay circuit 72 is input to the inversion instruction circuit 40A before the output signal of the n-turn delay circuit 70 , the inversion instruction circuit 40A outputs the inversion instruction f1 at the output timing of the m-turn delay circuit 72 . The drive signal generating circuit 42D receives the inversion command f1 and switches to a drive signal in a direction in which the objective lens 23 is separated from the optical disc 1 . Simultaneously, the focus guide circuit 32D having received the inversion command f1 is in a state capable of performing a guide operation based on the level determination of the focus error signal b.

When the objective lens 23 moves away from the optical disc 1 and the S-shaped waveform b4 is output from the focus error detection circuit 12, the focus guide circuit 32D judges the level of the focus error signal b4, and at the timing when the level reaches the guide level The switching command g is output to the switching circuit 31, the signal a output to the actuator driving circuit 21 is switched from the output signal of the driving signal generating circuit 42D to the output signal of the control circuit 20, and the focus guidance operation is performed by starting the control circuit 20 .

On the other hand, in this embodiment, an n-rotation delay circuit 70 is provided in the same manner as in Embodiments 1 and 2, but the information surface discrimination circuit cannot be performed due to noise contained in the output signal of the reflected light amount detection circuit 41 or the like. When discriminating the information plane of 84A, an inversion command f is outputted using the input signal from the n-rotation delay circuit 70 .

As described above, according to the present embodiment, the output signal of the driving signal generating circuit 42D causes the objective lens 23 to approach the optical disc 1, and the difference in the amount of reflected light at the timing of the peak and the valley of the focus error signal b is calculated, and the maximum value of the amount of reflected light is compared to the difference in the amount of reflected light. The value after positive normalization is compared with the predetermined value, and the information surface discrimination circuit 84A detects the information surface other than the surface 1C, and then the m-rotation delay circuit 72 outputs a signal after 1 (=m) rotation, and the inversion instruction circuit 40A outputs Invert instruction f. Thus, the second information surface 1B is detected, and then the objective lens 23 is only approached by the distance S to the optical disc 1. Even if the accuracy of the information surface discrimination circuit 84A is low, the objective lens 23 is not approached to the optical disc 1, and it is possible to achieve a narrow WD. Prevent the objective lens 23 from colliding with the optical disc 1 .

In addition, the focus error signal b and the reflected light amount signal c are used together for the focus point passing detection circuit 44 to detect the passage of the focus point position, thereby removing the noise of the focus error signal b, performing reliable focus point detection, and realizing stable Focus guide.

In addition, even if the reflected light amount signal c has noise or the like, the value N obtained by positively normalizing the reflected light amount difference with the maximum value of the reflected light amount is scattered, and when the information plane discrimination by the information plane discriminating circuit 84 fails, due to the use of n Since the rotation delay circuit 70 outputs the inversion command, the focus guidance operation can be reliably performed, and the objective lens 23 can be prevented from colliding with the optical disc 1, so that a highly reliable optical disc control device can be realized.

In addition, the timing of changing the direction of the objective lens 23 and starting the level determination of the focus error signal b for guidance is from the zero crossing of the first S-shaped waveform to after the optical disc 1 rotates n times (n is an integer), and from The zero-crossing of the S-shaped waveform other than the surface 1C is after the optical disc 1 rotates m times (m is an integer), so even if the optical disc 1 has a surface wobble component, when the level determination of the focus error signal b is started, It can also ensure that the focal point must be closer than the information surface 1A. In this way, it is possible to reliably perform focus guidance on the first information plane 1A.

In addition, by calculating the number of waiting rotations n and m, and the lens moving speeds Vlns and Vlns2 from the rotating speed Vrot of the optical disc 1, the lens moving speeds Vlns and Vlns2 are kept approximately constant even if the rotating speed Vrot of the optical disc 1 is different, so that the focus can be ensured. Stability while booting.

And, the amount of movement of the objective lens 23 from the detection of the initial S-shaped waveform to the rotation of the optical disc 1 after n turns and the amount of movement of the objective lens 23 from the detection of the S-shaped waveform other than the surface 1C to the rotation of the optical disk 1 after m turns can be respectively always Keeping the predetermined distances L and S, the objective lens 23 can be prevented from approaching the optical disc 1 unnecessarily.

In the present embodiment, the driving signal generation circuit 42C is described as a circuit that drives the objective lens 23 from the initial direction toward the optical disc 1 . However, the present invention is not limited thereto, and it is also possible to drive the objective lens 23 away from the optical disc 1 by a predetermined distance at first in consideration of the surface wobble of the optical disc 1, and then change direction and drive so as to approach the optical disc 1.

As a method of keeping the amount of movement of the objective lens 23 at the predetermined distance L or S, the following configuration may be used, and it is not limited to this embodiment. That is, make the lens moving speed Vlns or Vlns2 constant regardless of the rotational speed Vrot of the optical disc 1, and after the objective lens 23 moves only a predetermined distance L or S, it will stop at this position until the optical disc 1 rotates n or m revolutions. After rotating n or m turns, change direction. Similarly, the waiting number of rotations n or m may be set regardless of the rotation speed Vrot, and is not limited to this embodiment.

(Embodiment 5)

FIG. 12 is a block diagram showing a configuration example of an optical disk control device according to Embodiment 5 of the present invention. In FIG. 12 , the same reference numerals are assigned to the same components as those in the conventional example, Embodiment 1, Embodiment 2, Embodiment 3, and Embodiment 4, and description thereof will be omitted.

The S-shape polarity discrimination circuit 90 appears based on the maximum and minimum values of the focus error signal b from the focus error detection circuit 12 under the condition that the reflected light quantity signal c from the reflected light quantity detection circuit 41 is greater than or equal to a predetermined value Clv1 In the order of , for example, when a minimum value occurs followed by a maximum value, +1 is output, and when a maximum value occurs followed by a minimum value, -1 is output. The focus position judging circuit 91 adds the output signal from the S-shaped polarity judging circuit 90 when the reflected light amount signal c is less than or equal to the predetermined value Clv1, judges the current focus position based on the calculated value, and thereby detects The focus has passed the target information surface, and the reverse command f is output. The drive signal generation circuit 42E outputs a signal for moving the objective lens 23 away from or close to the optical disc 1 .

Next, the operation of the optical disc control device configured as above will be described with reference to the waveform diagrams of FIGS. 12 and 13 .

In FIG. 13, the optical disc 1 has a surface wobble component, and schematically shows that the portion irradiated with the laser beam shakes up and down due to the rotation of the optical disc 1. It is a sine wave superimposed on the output signal a of the drive signal generating circuit 42E in FIG. 13 . Among these sine waves, the solid line, dotted line, and dashed-dotted line represent the surface wobble components of the surface 1C, the second information surface 1B, and the first information surface 1A, respectively.

First, a focus guide command h is sent from the system controller 30 to the drive signal generation circuit 42E. The drive signal generating circuit 42E outputs a drive signal in a direction in which the objective lens 23 approaches the optical disc 1 at a predetermined speed. When the objective lens 23 approaches the optical disc 1, its focal point passes through the surface 1C, thereby outputting an S-shaped waveform b1 with a maximum value followed by a minimum value from the focus error detection circuit 12, and the S-shaped polarity discrimination circuit 90 outputs +1. At this point, the count value inside the focus position determination circuit 91 is +1.

Furthermore, when the objective lens 23 approaches the optical disc 1, its focal point passes through the second information surface 1B, thereby outputting the S-shaped waveform b2 in which the maximum value appears the minimum value from the focus error detection circuit 12, and the S-shaped polarity discrimination circuit 90 outputs +1. At this point, the count value inside the focus position determination circuit 91 is +2.

When in this state, the objective lens 23 is driven close to the direction of the optical disc 1, the distance between the objective lens 23 and the optical disc 1 increases due to the surface wobble that the optical disc 1 has, and the focal point passes through the 2nd information surface 1B and the surface C in turn. Therefore, the S-shaped waveform (b3, b4) in which the minimum value appears the maximum value followed by the minimum value is continuously output from the focus error detection circuit 12 twice, and the S-shaped polarity determination circuit 90 outputs -1 twice. Accordingly, the count value inside the focus position determination circuit 91 changes in +1, 0.

When the objective lens 23 is driven in this state in a direction in which it approaches the optical disc 1, the shaking of the optical disc 1 caused by the surface wobble subsides, and the focal point passes through the surface 1C (S-shaped waveform b5) and the second information surface 1B ( S-shaped waveform b6), the first information plane 1A (S-shaped waveform b7), this time, the S-shaped polarity discriminating circuit 90 outputs +1. At this time, the focus position discriminating circuit 91 changes its internal count value by +1, +2, +3, and outputs the inversion instruction f to the focus guide circuit 32E and the drive signal generating circuit 42E at the timing of +3.

The drive signal generation circuit 42E receives the inversion command f, and switches to a drive signal in a direction in which the objective lens 23 is separated from the optical disc 1 . Simultaneously, the focus guidance circuit 32E having received the inversion command f is in a state capable of performing a guidance operation based on the level determination of the focus error signal b.

When the objective lens 23 moves away from the optical disc 1 and the S-shaped waveform b8 is output from the focus error detection circuit 12, the focus guide circuit 32E judges the level of the focus error signal b8, and at the timing when the level reaches the guide level The switching command g is output to the switching circuit 31 , the signal a output to the actuator driving circuit 21 is switched from the driving signal generating circuit 42E to the output signal of the control circuit 20 , and the control circuit 20 is activated to perform focus guidance operation.

As described above, in this embodiment, the output signal of the drive signal generating circuit 42E causes the objective lens 23 to approach the optical disc 1, and the S-shaped polarity is judged based on the order in which the peaks and valleys of the focus error signal b appear, and the focus position is judged based on the judgment result. position, thereby detecting the target information surface. Next, when the target information plane is detected, the direction is changed immediately, and the objective lens 23 is driven so as to be far away from the optical disc 1, and then focus guide operation is performed using the generated focus error signal b. In this way, the objective lens 23 can immediately enter the focus guide operation without repeatedly moving up and down, so the time required for the focus guide operation can be shortened. Furthermore, by making the objective lens 23 close to the optical disc 1 and changing the direction immediately after the target information surface is detected, the objective lens 23 does not need to approach the optical disc 1 unnecessarily, and collision between the objective lens 23 and the optical disc 1 can be prevented even when the WD is narrow.

The S-shaped polarity determination circuit 90 and the focus position determination circuit 91 use the focus error signal b and the reflected light amount signal c from the reflected light amount detection circuit 41 to remove the noise of the focus error signal b during their respective operations, thereby performing reliable operations. , thereby achieving stable focus guidance.

In the present embodiment, the drive signal generating circuit 42E is described as a circuit that drives the objective lens 23 from the beginning to a direction approaching the optical disc 1 . However, the present invention is not limited thereto, and it is also possible to drive in consideration of the surface wobble of the optical disc 1, so that the objective lens 23 is only a predetermined distance away from the optical disc 1 at first, and then change the direction and drive so as to approach the optical disc 1.

As described above, according to the present invention, the objective lens can immediately enter the focus guide operation without repeatedly moving up and down, so the time required for the focus guide operation can be shortened.

In addition, the objective lens does not need to approach the optical disc unnecessarily, and it is possible to prevent the objective lens from colliding with the optical disc even when the WD is small.

In addition, even for an optical disc having a plurality of information planes inside, the target information plane can be reliably detected, and a reliable focus guidance operation can be performed on the target information plane.

Claims (18)

1. optical disc controller comprises:

Assemble irradiation unit, the information carrier with a plurality of information faces is assembled illumination beam via object lens;

Focus on mobile device,, the focus of the light beam of being assembled by above-mentioned convergence irradiation unit is moved on the normal direction of the face of above-mentioned information carrier by moving above-mentioned object lens;

Focusing-error detecting device generates focus error signal, and this focus error signal is corresponding to the offset of the focus of each face of the above-mentioned relatively information carrier of light beam;

Focus point detects surface and each information faces that beams focusing point has passed through above-mentioned information carrier by pick-up unit;

The counter-rotating command device uses from above-mentioned focus point and exports the counter-rotating instruction by the output signal of pick-up unit;

Driving signal generator, output makes the signal of above-mentioned object lens near above-mentioned information carrier to above-mentioned focusing mobile device, and switches to according to above-mentioned counter-rotating instruction and to make the signal of above-mentioned object lens away from above-mentioned information carrier, and output;

Control device uses above-mentioned focus error signal to control above-mentioned focusing mobile device, makes focus point follow the trail of each information faces of above-mentioned information carrier; And

Focus on guiding device,, will move and switch to above-mentioned control device, focus on the guiding action by above-mentioned focusing mobile device from above-mentioned driving signal generator by switching command.

2. optical disc controller according to claim 1 is characterized in that, above-mentioned optical disc controller also comprises:

Amplitude detecting device detects the amplitude of above-mentioned focus error signal; And

The characteristic correcting device, use above-mentioned amplitude detecting device focus point by the time amplitude, the ride gain characteristic of above-mentioned control device is revised, the control action that make to focus on after the guiding is stable.

3. optical disc controller according to claim 1 is characterized in that, above-mentioned optical disc controller also comprises:

The reflection light quantity pick-up unit, detect with from the corresponding signal of the catoptrical light quantity of above-mentioned information carrier;

Above-mentioned focus point based on the output signal from above-mentioned reflection light quantity pick-up unit, detects passing through of focus point by pick-up unit.

4. optical disc controller according to claim 1 is characterized in that:

The signal that the inclination of above-mentioned driving signal generator output drive waveforms when switching the signal corresponding with above-mentioned counter-rotating instruction little by little changes.

5. optical disc controller according to claim 3 is characterized in that, above-mentioned optical disc controller also comprises:

Amplitude detecting device detects the amplitude of above-mentioned focus error signal;

The spherical aberration adjustment device carries out variable setting according to target face to the amount of spherical aberration of the focus of the light beam assembled by above-mentioned convergence irradiation unit; And

The information faces pick-up unit uses the output signal from above-mentioned amplitude detecting device, detects above-mentioned target face from a plurality of information faces of above-mentioned information carrier.

6. optical disc controller according to claim 5 is characterized in that, above-mentioned optical disc controller also comprises:

The phase relation pick-up unit, from the level of the reflected light amount signal of above-mentioned reflection light quantity pick-up unit and from the maximum value of the reflected light amount signal of above-mentioned reflection light quantity pick-up unit, detect the phase relation of above-mentioned focus error signal and above-mentioned reflected light amount signal when getting maximum value and minimal value based on above-mentioned focus error signal;

Above-mentioned information faces pick-up unit is based on the phase relation from the output of above-mentioned phase relation pick-up unit, detects above-mentioned target face from a plurality of information faces of above-mentioned information carrier.

7. optical disc controller according to claim 6 is characterized in that:

When above-mentioned phase relation pick-up unit detected the phase relation of above-mentioned focus error signal and above-mentioned reflected light amount signal, above-mentioned focus error signal is maximum value and minimizing timing detection with the level of above-mentioned reflected light amount signal was condition more than or equal to predetermined value.

8. optical disc controller according to claim 1 is characterized in that, above-mentioned optical disc controller also comprises:

Amount of movement management pick-up unit A detects by pick-up unit above-mentioned focus point and to move scheduled volume by the focus point rear focal point and manage and detect;

Above-mentioned counter-rotating command device is based on the output signal from above-mentioned amount of movement management pick-up unit A, to replace from the output signal of above-mentioned focus point by pick-up unit output counter-rotating instruction.

9. optical disc controller according to claim 8 is characterized in that, above-mentioned optical disc controller also comprises:

Rotating driving device is rotated driving with predetermined rotating speed to above-mentioned information carrier; And

Revolution management pick-up unit is benchmark with above-mentioned focus point by the position that pick-up unit has detected the above-mentioned information carrier by focus point, above-mentioned information carrier has only been rotated predetermined revolution managed and detected to the said reference position afterwards;

Above-mentioned counter-rotating command device uses from the output signal of above-mentioned amount of movement management pick-up unit A and the output signal of managing pick-up unit from above-mentioned revolution, to replace from the output signal of above-mentioned focus point by pick-up unit, exports above-mentioned counter-rotating instruction.

10. optical disc controller according to claim 8 is characterized in that, above-mentioned optical disc controller also comprises:

The information faces discriminating gear, whether differentiate above-mentioned focus point is the target face of channeling conduct by the detected face of pick-up unit;

Above-mentioned counter-rotating command device uses from the output signal of above-mentioned amount of movement management pick-up unit A with from the output signal of above-mentioned information faces discriminating gear, to replace from the output signal of above-mentioned focus point by pick-up unit, exports above-mentioned counter-rotating instruction.

11. optical disc controller according to claim 1 is characterized in that, above-mentioned optical disc controller also comprises:

The focal position pick-up unit, the focal position of each information faces in the above-mentioned relatively information carrier of detection light beam;

S word polarity discriminating device, when above-mentioned focal position pick-up unit detects the focal position of each information faces of the above-mentioned relatively information carrier of light beam, the S word signal that output is formed by the maximum value and the minimal value of above-mentioned focus error signal, and to differentiate be to be minimizing order after the maximum value, and still minimal value is the order of maximum value afterwards.

12. optical disc controller according to claim 11 is characterized in that, above-mentioned optical disc controller also comprises:

The reflection light quantity pick-up unit, detect with from the corresponding signal of the reflection light quantity of above-mentioned information carrier;

During the focal position of each information faces in above-mentioned focal position pick-up unit detects the above-mentioned relatively information carrier of light beam, the reflected light amount signal from above-mentioned reflection light quantity pick-up unit when getting maximum value and minimal value with above-mentioned focus error signal is a condition more than or equal to predetermined value.

13. optical disc controller according to claim 1 is characterized in that, above-mentioned optical disc controller also comprises:

The face discriminating gear, differentiating by above-mentioned focus point is the predetermined face that above-mentioned information carrier comprises by the detected face of pick-up unit;

The amount of movement setting device based on the output signal from above-mentioned discriminating gear, is set the amount of movement of above-mentioned object lens;

Amount of movement management pick-up unit B detects the amount of movement that only moves the object lens that set by above-mentioned amount of movement setting device by the focus point rear focal point to above-mentioned focus point by pick-up unit and manages and detect; And

Above-mentioned counter-rotating command device uses the output signal from above-mentioned amount of movement management pick-up unit B, to replace from the output signal of above-mentioned focus point by pick-up unit output counter-rotating instruction.

14. optical disc controller according to claim 13 is characterized in that, above-mentioned optical disc controller also comprises:

Rotating driving device is rotated driving with predetermined rotating speed to above-mentioned information carrier;

Revolution management pick-up unit is benchmark with above-mentioned focus point by the position that pick-up unit has detected the above-mentioned information carrier by focus point, above-mentioned information carrier has only been rotated predetermined revolution managed and detected to the said reference position afterwards;

Above-mentioned counter-rotating command device uses from the output signal of above-mentioned amount of movement management pick-up unit B and the output signal of managing pick-up unit from above-mentioned revolution, to replace from the output signal of above-mentioned focus point by pick-up unit, exports above-mentioned counter-rotating instruction.

15. optical disc controller according to claim 1 is characterized in that, above-mentioned optical disc controller also comprises:

Amount of movement is managed pick-up unit A, above-mentioned focus point is detected by the only mobile scheduled volume A of focus point rear focal point by pick-up unit manage and detect;

The face discriminating gear, differentiating by above-mentioned focus point is the predetermined face that above-mentioned information carrier comprises by the detected face of pick-up unit;

The amount of movement setting device based on the output signal from above-mentioned discriminating gear, is set the amount of movement of above-mentioned object lens; And

Amount of movement management pick-up unit B detects the amount of movement that only moves the object lens that set by above-mentioned amount of movement setting device by the focus point rear focal point to above-mentioned focus point by pick-up unit and manages and detect;

Above-mentioned counter-rotating command device according to from the generation of the output signal of above-mentioned amount of movement management pick-up unit B regularly with from the generation regularly of the output signal of above-mentioned amount of movement management pick-up unit A any one, to replace from the output signal of above-mentioned focus point output counter-rotating instruction by pick-up unit.

16. optical disc controller according to claim 15 is characterized in that, above-mentioned optical disc controller also comprises:

Rotating driving device is rotated driving with predetermined rotating speed to above-mentioned information carrier;

Revolution management pick-up unit is benchmark with above-mentioned focus point by the position that pick-up unit has detected the above-mentioned information carrier by focus point, above-mentioned information carrier has only been rotated predetermined revolution managed and detected to the said reference position afterwards;

Above-mentioned counter-rotating command device is except using the output signal or the output signal from above-mentioned amount of movement management pick-up unit B from above-mentioned amount of movement management pick-up unit A, also use output signal from above-mentioned revolution management pick-up unit, to replace, export above-mentioned counter-rotating instruction from the output signal of above-mentioned focus point by pick-up unit.

17., it is characterized in that above-mentioned optical disc controller also comprises according to claim 9,14 or 16 described optical disc controllers:

Revolution speed setting device, according to the above-mentioned predetermined revolution of the revolution speed calculating of above-mentioned information carrier, the above-mentioned predetermined revolution that set-up and calculated goes out in above-mentioned revolution management pick-up unit.

18. according to Claim 8,13 or 15 described optical disc controllers, it is characterized in that above-mentioned optical disc controller also comprises:

Speed setting device drives the speed of above-mentioned object lens, the speed that set-up and calculated goes out in above-mentioned driving signal generator according to the revolution speed calculating of above-mentioned information carrier.

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