JP3489780B2 - Focus servo control device and disk reproducing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CD player, C
The present invention relates to a disk reproducing device such as a D-ROM and a DVD-ROM, and particularly to a focus servo control circuit used in a DVD system.

[0002]

2. Description of the Related Art A disk reproducing apparatus used for audio / visual audio equipment and computer peripheral equipment is constructed as shown in the system diagram of FIG. A pit row on the disk 11 rotated by the disk motor 13 is irradiated with a beam generated from a laser pickup (PU) 12, and the beam reflected from the beam is converted into an electric signal (RF signal) by an optical element such as a photodiode. Pit information is obtained by converting. The converted RF signal is further amplified by the RF amplifier 15. The amplified RF signal is binarized into a digital signal and then PL
It is supplied to the L (Phase Lock Loop) circuit. The PLL circuit generates a bit clock signal extracted based on the data signal. The data signal is sent to the signal processing circuit 26 together with the bit clock signal. The signal processing circuit 26 receives the data signal as input, detects the synchronization pattern, demodulates the data,
It is a circuit for performing processing such as deinterleaving and error correction using the correction RAM 27, and audio data or computer data is output to the outside only after performing these processing.

Further, a system relating to the focus servo control circuit will be described with reference to FIG. The signal read by the pickup 12 from the disk 11 is input to the RF amplifier (RFamp) 15, and the tracking error signal TE, the focus servo signal FE, and the RF signal which is an information signal are extracted from the RF amplifier 15. The tracking error signal TE is input to the tracking servo control circuit 16, the gain and phase are compensated, and seek control is performed. The output signal of the tracking servo control circuit 16 is input to the actuator driver 19 to drive the tracking actuator of the pickup 12. The output of the output equalizer of the tracking servo control circuit 16 is also sent to the feed motor control circuit 17 and drives the feed motor 14 through the motor driver 18. The focus error signal FE is
It is input to the focus servo equalizer (EQ) 21 through the servo on / off (ON / OFF) switch 20. This output signal is added to the signal generated by the lens drive signal generation circuit 23 and sent to the focus actuator driver 22. Then, the focus actuator of the pickup 12 is driven.

The RF signal consists of a data sampling circuit and C
The data is sent to the D / DVD data signal processing circuit 26, binarized by the data extracting circuit, the bit clock is extracted, the synchronization signal is extracted, and then the correction processing is performed using the demodulation / correction RAM 27. The synchronization signal is sent to the disk motor control circuit 24 and controls the disk motor 13 through the disk motor driver 25. In the case of a DVD movie, the data corrected by the data signal processing circuit 26 is M
PEG video decoder, audio decoder processing circuit 2
Then, the video signal and the audio signal are output. In the case of a DVD-ROM, the output data from the data signal processing circuit 26 is sent to the data buffer circuit 28,
Send the data as digital data to the host personal computer. The system controller 29 controls the control timing of each control circuit and the operation of the entire set.

FIG. 8 is a timing chart showing the movement of the beam spot (lens) and the movement of each signal during the movement between layers (hereinafter referred to as the layer jump). D represents the distance between the first and second layers of the disc, which is the DVD
In the case of a system, for example, it is about 55 μm. (A)
Is the case where the surface wobbling direction of the disk is the same as the moving direction of the beam spot (upward in this case). The speed of the beam spot in the layer direction is relatively low with respect to the disk surface. (B) and (C) are cases where the disc surface deviation direction is opposite to the beam spot movement direction (downward in this case). The speed of the beam spot in the layer direction is relatively high with respect to the disk surface.

[0006]

As described above, even in the same disc, the relative movement speed condition of the beam spot and the disc surface changes depending on the location (surface deviation state). ON again
When you do, layer jump may fail. In the figure, (A) and (B) show the case of success, and (C) shows the case of failure. In the case of (C), the beam spot has moved away from the destination layer. However, the focus servo layer jump operation is a very important operation in the DVD system, and since there are only two layers, unlike the tracking servo track jump operation,
If you fail a layer jump, you will not settle into another layer. As a result, there is a large amount of failure when it fails. Further, if the microcomputer fails, the microcomputer must return the servo to the initial state and perform the focus search, so that it takes a long time for recovery. This phenomenon is determined by the runout distance and the rotation speed. From such a point, it is important to improve the accuracy of the layer jump operation. The present invention has been made in view of the above circumstances, and brakes are applied from before the actual focusing position even in the case where the relative speed of the beam spot and the disk changes greatly in a disk with a lot of surface wobbling. Thus, a focus servo control system in a DVD system capable of realizing stable layer jump is provided.

[0007]

A feature of the present invention is that a DVD
In the focus servo control used in the system, it is to improve the reliability when the beam spot is moved between layers of a disc having a two-layer structure. Conventionally, when moving between layers (hereinafter referred to as layer jump), the relative speed of the beam spot and the pit surface of the disc changes due to the surface wobbling caused by the rotation of the disc. It has been considered difficult to perform a stable layer jump at the position of, but in the present invention, when the layer jump is performed, the brake is applied using the differential signal of the focus error signal, and then the servo is turned on at the zero cross point. The feature is that the brake is applied from before the actual focus position. By braking from before this actual focus position, you can decelerate sufficiently,
As a result, it became possible to perform stable servo-on operation at the in-focus position.

That is, the focus servo control device of the present invention includes a focus error detection unit that detects a focus of a beam spot based on a signal read from a disc via an optical pickup, and an output of the focus error detection unit. Differentiating means for outputting the high frequency component of the, the comparing means for comparing the output level of the focus error detecting means with a preset level, and the focus lens is accelerated from the layer currently being reproduced to the other layer. comprising an accelerating means, the adding means for injecting the focus servo output of said differentiating means switched according to the result of said comparing means and said accelerating means and said differentiating means, the focus error
-Additional integration means for outputting the low-frequency component of the output of the detection means
In preparation for this, the operation signal of the focus servo is
At the same time as operating with the output of the stage,
Accelerate the cus lens to the other layer, and output it to the comparison means.
Inject the output of the differentiating means to the focus servo accordingly
When the polarity of the output of the differentiating means is reversed, the
The normal state of the circus servo is restored and the differential
From the point where the polarity of the means is reversed,
Focus equalizer output that operates the focus servo
It is characterized by further comprising a mute means for shutting off . Further, the focus servo control device of the present invention is
A disc on which data is recorded on a recording surface of a plurality of layers is selectively irradiated with a light beam, and based on a signal read from reflected light on a selected recording surface of the recording surface of the plurality of layers of the disc. A focus servo control device for adjusting the focus position of the light beam to the selected recording surface,
The focus position of the light beam, a focus error detector that detects a deviation between the selected recording surface among the recording surfaces of the plurality of layers, and the output of the focus error detector based on the output of the light beam, A focus servo equalizer that corrects the focus position, a system control circuit that controls the operation of the focus servo equalizer, a differentiation circuit that outputs a high frequency component of the output of the focus error detector, and the focus error detector Controlled by the system control circuit, which compares an output level with a preset level and outputs an activation signal when the output level of the focus error detector exceeds the preset level. A control signal that causes the focal position of the light beam to jump from one of the recording surfaces of the plurality of layers to the other. Generated jump signal generating circuit, a selector for selecting and outputting any one of the output of the differentiating circuit and the output of the jump signal generating circuit according to the output of the comparator, and the output of the selector is the focus. An adder for adding to the output of the servo equalizer ,
Product that outputs the low-frequency component of the output of the focus error detector
Further comprises a branch circuit, wherein the system control circuit is
The focus is used as input for the focus servo equalizer.
Switch the output of the error detector to the output of the integrating circuit
Change and control from the jump signal generation circuit
The focus position of the light beam is indicated by a signal and is recorded in the plurality of layers.
Jump from one side of the recording surface to the other, and further forward
The comparison circuit outputs the activation signal,
After the output is output to the adder, the differentiation circuit
When the output polarity is reversed, the focus servo
While activating the position corrector of the equalizer,
Connected to the output side of the focus servo equalizer,
From the place where the polarity of the output of the differentiating circuit is reversed,
Output the focus servo equalizer for a fixed time.
It is characterized by further including a mute circuit for cutting off .

The disc reproducing apparatus of the present invention irradiates an optical recording disc with a laser and picks up the reflected light, and a focus of a beam spot based on a signal read from the disc through the pickup unit. A focus error detecting means for detecting, a differentiating means for outputting a high frequency component of the output of the focus error detecting means, a comparing means for comparing the output level of the focus error detecting means with a preset level, and Acceleration means for accelerating the focus lens from the currently reproducing layer to the other layer, and switching between the differentiating means and the accelerating means according to the result of the comparing means. comprising means, the full
Product that outputs the low-frequency component of the output of the focus error detection means
And a focus servo operation signal.
Is operated by the output of the integration means, and at the same time, the acceleration
By means of accelerating the focus lens to the other layer, the comparison
The output of the differentiating means in accordance with the output of the means.
And the polarity of the output of the differentiating means is reversed.
Roll the focus servo back to normal and
After the polarity of the differentiating means is reversed, a predetermined time
Focus equalizer that operates focus servo only
It is further characterized by further comprising a mute means for cutting off the output of the z . In addition, the disc reproducing apparatus of the present invention, a disc having data recorded on the recording surface of a plurality of layers,
A disc reproducing apparatus for selectively irradiating a light beam and reproducing the data based on a signal read from reflected light of a selected recording surface of the recording surfaces of the plurality of layers of the disk, comprising: A pickup that reads reflected light, and a focus error detection that detects a deviation between the focal position of the light beam and the selected recording surface among the plurality of recording surfaces based on the reflected light read by the pickup. And a focus servo equalizer that corrects the focus position of the light beam based on the output of the focus error detector, a system control circuit that controls the operation of the focus servo equalizer, and the output of the focus error detector. , The output level of the focus error detector is preset. A comparator for outputting an activation signal when the output level of the focus error detector exceeds the preset level, and a focus position of the light beam controlled by the system control circuit. A jump signal generating circuit for generating a control signal for jumping from one of the recording surfaces of the plurality of layers to the other, and one of the output of the differentiating circuit and the output of the jump signal generating circuit according to the output of the comparator. comprising a selector for selecting and outputting, and an adder for adding the output of the selector to the output of the focus servo equalizer, the Four
Integral for outputting the low-frequency component of the output of the cass error detector
A circuit further comprising the system control circuit
The focus is used as input for the focus servo equalizer.
Switch the output of the error detector to the output of the integrating circuit
Control signal from the jump signal generating circuit.
The focal position of the light beam with the recording of the multiple layers.
Jump from one side of the surface to the other,
The comparison circuit outputs the activation signal and the output of the differentiation circuit.
After the force is output to the adder, the output of the differentiating circuit
When the polarity of force is reversed, the focus servo equal
While activating the position correction operation of the riser,
Connected to the output side of the focus servo equalizer,
From the point where the polarity of the output of the differentiator circuit is reversed,
The output of the focus servo equalizer is blocked for
It is characterized by further including a mute circuit for cutting off .

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, referring to FIG. 1 and FIG.
An example will be described. FIG. 1 is a block diagram of a DVD system of the present invention, and FIG. 2 is a timing diagram for explaining a layer jump operation of the DVD system. A pit row on the disk 11 rotated by the disk motor 13 is irradiated with a beam generated from a laser pickup (PU) 12, and the beam reflected from the beam is converted into an electric signal (RF signal) by an optical element such as a photodiode. Pit information is obtained by converting. The converted RF signal is further amplified by the RF amplifier 15. The amplified RF signal is binarized into a digital signal and then PL
It is supplied to the L (Phase Lock Loop) circuit. The PLL circuit generates a bit clock signal extracted based on the data signal. The data signal is sent to the signal processing circuit 26 together with the bit clock signal. The signal processing circuit 26 receives the data signal as input, detects the synchronization pattern, demodulates the data,
It is a circuit for performing processing such as deinterleaving and error correction using the correction RAM 27, and audio data or computer data is output to the outside only after performing these processing.

Next, a system relating to the focus servo control circuit will be described. The signal read from the disk 11 by the pickup 12 is an RF amplifier (R
Famp) 15, and the tracking error signal TE, the focus servo signal FE, and the RF signal which is an information signal are extracted from the RF amplifier 15. The tracking error signal TE is input to the tracking servo control circuit 16, the gain and phase are compensated, and seek control is performed. This tracking servo control circuit 16
Is output to the actuator driver 19 and drives the tracking actuator of the pickup 12. The output of the output equalizer of the tracking servo control circuit 16 is also sent to the feed motor control circuit 17 and drives the feed motor 14 through the motor driver 18. The focus error signal FE is input to the focus servo equalizer (EQ) 21 through the servo on / off (ON / OFF) switch 30. This output signal is added to the signal generated by the lens drive signal generation circuit 23 and sent to the focus actuator driver 22 by the switch 35. Then, the focus actuator of the pickup 12 is driven.

The RF signal is supplied to the data sampling circuit and C
The data is sent to the D / DVD data signal processing circuit 26, binarized by the data extracting circuit, the bit clock is extracted, the synchronization signal is extracted, and then the correction processing is performed using the demodulation / correction RAM 27. The synchronization signal is the disk motor control circuit 2
4 and controls the disc motor 13 through the disc motor driver 25. In addition, the data signal processing circuit 2
The data corrected in 6 is MP for DVD movies.
EG video decoder, audio decoder processing circuit 28
And then output the video and audio signals.
In the case of a DVD-ROM, the output data from the data signal processing circuit 26 is sent to the data buffer circuit 28 and sent as digital data to the host personal computer or the like.
The system controller 29 controls the control timing of each control circuit and the operation of the entire set.

The FE signal output from the RF amplifier 15 is a low-pass filter LPF31 and a high-pass filter H.
It is input to the PF 32 and the window comparator 33. The window comparator 33 is composed of two comparators and an OR circuit (OR circuit) that inputs the outputs of these comparators. The output of the LPF 31 is switched between the FE signal and the switch 30 and sent to the focus servo equalizer 21. The output of the high pass filter HPF 32 is sent to the polarity comparator 34, and the system controller 29 generates the servo-on timing. The outputs of the window comparator 33 and the lens drive signal generation circuit 23 are the high pass filter HPF3.
It is switched by the output of 2 and the switch 35. This signal becomes a lens acceleration and deceleration signal necessary for performing a layer jump. This signal is added to the output of the focus servo equalizer 21 and sent to the focus actuator driver 22 to drive the focus lens.
The switch 35 described above is switched by the output of the window comparator 33. The window comparator 33 compares the FE signal with a predetermined level determined in advance,
It is detected that the FE signal has exceeded its predetermined level.

FIG. 2 is an operation timing chart of this embodiment. The focus servo is switched from the point on the first layer 3
At 0, it is switched to the output of the low pass filter LPF31. This is to hold the position of the lens corresponding to the position of the surface deviation of the disc at that time. After that, the lens starts moving toward the second layer by the acceleration voltage output from the drive signal generating circuit 23. The FE signal starts to appear when the beam spot approaches the second layer. When the standby level determined by the window comparator 33 is reached, the switch 35 is switched, the output of the high pass filter HPF 32 is added to the output of the focus servo equalizer 21, and the result is applied to the focus actuator driver 22. That is, the deceleration pulse is injected into the focus servo. This high pass filter HP
The added polarity of the signal of F32 must be added in the braking direction of the lens. And while slowing down,
When the polarity comparator 34 is inverted, the focus servo is turned on again at S (zero cross point) to start the pull-in operation. From here, the output of the focus servo equalizer 21 is applied to the driver. Completed moving to the second layer.
The focus error signal FE is position information, and a speed signal (that is, a differential signal of the focus error signal) is output based on this information. The speed signal has a function of keeping the target speed within a certain range.

This operation can be executed by the same algorithm when moving from the second layer to the first layer. By this operation, the accuracy of the layer jump is increased, and a more reliable layer jump can be realized. Next, a second embodiment will be described with reference to FIGS.
FIG. 3 is a system diagram including a focus servo control circuit of a DVD system which is a disc reproducing device, and FIG. 4 is an operation timing chart thereof. The electric signal read by the pickup 12 from the disk 11 is input to the RF amplifier (RFamp) 15, and the tracking error signal TE, the focus servo signal FE, and the RF signal used as an information signal are extracted from the RF amplifier 15. The TE signal and the FE signal are analog-digital (AD) converted by an analog-digital (AD) converter 40. The data converted to these digital values is
It is latched in the TE register 41 and the FE register 42, respectively.

The data in the TE register 41 is sent to the digital tracking servo control circuit 43. The output is converted into an analog value by the DA converter 46 and sent to the actuator driver 19. On the other hand, the output of the servo control circuit 43 is also sent to the digital feed motor control circuit 44, converted into an analog value by the DA converter 45, and sent to the driver 18. The output of the actuator driver 19 drives a tracking actuator (not shown) of the pickup 12, and the output of the motor driver 18 is
The feed motor 14 is driven. The RF signal is also sent to the data sampling circuit and the CD / DVD data signal processing circuit 26, binarized by the data sampling circuit, bit clock extraction and sync signal extraction are performed, and then demodulation and correction RAM.
Correction processing is performed using 27. The synchronization signal is sent to the disk motor control circuit 24 and the disk motor driver 2
The disk motor 13 is controlled through 5. In the case of a DVD movie, the data corrected by the data signal processing circuit 26 is sent to an MPEG video decoder or audio decoder processing circuit 28, and then a video signal or audio signal is output. In the case of a DVD-ROM, the output data from the data signal processing circuit 26 is sent to the data buffer 28 and sent as digital data to the host personal computer or the like. The system controller 29 controls the control timing of each control circuit and the operation of the entire set.

The AD converter 40 converts the TE and FE signals into AD signals.
The data converted and converted to digital values are
It is latched by the TE register 41 and the FE register 42.
The data in the TE register 41 is sent to the digital tracking servo control circuit 43. The output is converted into an analog value by a DA (digital analog) converter 46,
It is sent to the driver 19. On the other hand, the output of the servo control circuit 43 is also sent to the digital feed motor control circuit 44, is converted into an analog value by the DA converter 45, and is output to the driver 1
8 to drive the feed motor 14. The focus error data FE latched in the FE register 42 is the digital low pass filter LPF 52, the digital high pass filter HPF 53, and the window comparator 54.
Sent to. The output of the low pass filter LPF52 is F
The digital focus servo equalizer (EQ) 5 is switched by the data of the E register 42 and the selector 51.
Sent to 0. The polarity bit MSB of the high pass filter HPF53 is sent to the system controller 29 to generate the servo-on timing. The outputs of the window comparator 54 and the lens drive signal generation circuit 57 are switched by the output of the high pass filter HPF 53 and the selector 56.

This signal becomes a lens acceleration and deceleration signal necessary for performing a layer jump. This signal is
The signal is added to the output of the digital focus servo equalizer 50, passed through the mute switch 59, converted into an analog signal by the DA converter 47, and sent to the driver 22. Then, the focus lens of the pickup 12 is driven. The selector 56 is switched by the output of the window comparator 54. The window comparator 54 compares a predetermined level preset in the standby register 55 with the absolute value of the data in the FE register 42, detects that the FE signal exceeds the predetermined level, and causes the selector 51 to generate a lens drive signal. The output of the circuit 57 is switched to the output of the high pass filter HPF53.

FIG. 4 is an operation timing chart of this embodiment. The focus servo is selector 5 from the first layer
At 1, the output of the low pass filter LPF 52 is switched. This is to hold the position of the lens corresponding to the position of the surface deviation of the disc at that time. After this, by the acceleration voltage output from the drive signal generation circuit 57,
The lens starts moving toward the second layer. When the beam spot approaches the second layer, the FE signal starts to appear. Then, when the standby level determined by the window comparator 54 is reached, the selector 56 is switched, the output of the high pass filter HPF 53 is added to the output of the focus servo equalizer 50, and the sum is applied to the focus actuator driver 22 to brake the lens moving speed. Takes. The addition polarities of the signals of the high pass filter HPF53 must be added in the braking direction of the lens. Then, when the polarity bit of the FE signal is inverted while decelerating, the focus servo is turned on again to start the pull-in operation. From here, the output of the focus servo equalizer 50 is applied to the driver 22.

However, the hatched portion in the figure is a signal (acceleration signal and acceleration signal) that causes the lens to accelerate once due to the response of the focus servo equalizer 50, even though the lens has been sufficiently accelerated up to this point. The same polarity) is applied to the driver 22. In order to prevent this, in this embodiment, the mute switch 59 is operated for a time corresponding to a predetermined time (time during which the focus servo equalizer 50 outputs the acceleration signal) from the time when the servo is turned on.
Is operated for a time T0 determined by the timer circuit 58 so that the acceleration signal is not applied to the driver 22 (see the lower part of FIG. 4). That is, the focus EQ
In the output of 50, the hatched portion is deleted and the adverse effect due to this is eliminated. Then, the movement to the second layer is completed. This operation can be executed by the same algorithm when moving from the second layer to the first layer. By this operation, the accuracy of the layer jump is increased, and a more reliable layer jump can be realized.

Next, a third embodiment will be described with reference to FIGS. FIG. 5 shows a DVD which is a disc reproducing device.
6 is a partial system diagram including the focus servo control circuit of the system, and FIG. 6 is an operation timing chart thereof. This example is basically the same as the system of FIG.
The feature is that the output of the window comparator is not input to the selector by using the timer circuit. That is, the selector 56 is switched by the output of the window comparator 54. The window comparator 54 compares a predetermined level preset in the standby register 55 with the absolute value of the data in the FE register 42, detects that the FE signal exceeds the predetermined level, and causes the selector 51 to generate a lens drive signal. It has a role of switching from the output of the circuit 57 to the output of the high pass filter HPF 53. According to FIG. 5, an AND circuit is inserted between the window comparator 54 and the selector 56. One input of the AND circuit is connected to the output side of the window comparator 54, the other input is connected to the timer circuit 60 via an inverter, and the output is connected to the selector 56. The input of the inverter is connected to the timer circuit 60 and the output is connected to the other input of the AND circuit. The timer circuit 60 is controlled by the system controller 29.

Among recent pickups, pickups having two lenses, one lens having two focal points, and being compatible with both CDs and DVDs are increasing. However, the characteristic of this type of pickup is that the focus error signal FE tends to have two peaks (F in FIG. 6).
E signal (b)). Therefore, in this embodiment, in order to cope with such a pickup, the system shown in FIG. 3 is modified and a part of the circuit is changed as shown in FIG. That is, as described above, the window comparator 54
The timer circuit 60 is added to the output of. The timer circuit 60 generates a gate signal (malfunction prevention window signal) at the same time when the layer jump is started. This gate signal outputs "H" level for a predetermined time tw. The gate time tw sets the time required to exit the current layer. By this operation, even if the standby level is accidentally applied to the second small mountain, it is possible to prevent the malfunction. By adding this timer circuit, it becomes possible to perform a highly reliable layer jump even for a one-lens type pickup.

[0023]

According to the present invention, the beam spot (lens) can be formed on a disk or the like having a large amount of surface wobbling.
Since it is possible to realize a stable layer jump even when the relative speed of the disk and the relative speed change significantly, it is possible to improve the reliability of the set.

[Brief description of drawings]

FIG. 1 is a block diagram of a DVD system of the present invention.

FIG. 2 is a timing diagram illustrating the operation of layer jump of the DVD system of the present invention.

FIG. 3 is a block diagram of a DVD system of the present invention.

FIG. 4 is a timing diagram illustrating the operation of layer jump of the DVD system of the present invention.

FIG. 5 is a partial block diagram of the DVD system of the present invention.

FIG. 6 is a timing diagram illustrating the operation of layer jump of the DVD system of the present invention.

FIG. 7 is a block diagram of a conventional DVD system.

FIG. 8 is a timing diagram illustrating the operation of layer jump of the conventional DVD system.

[Explanation of symbols]

11 ... Disc, 12 ... Pickup, 1
3 ... Disk motor, 14 ... Feed motor,
15 ... RF amplifier (RFamp), 16 ...
Tracking servo control circuit, 17 ... Feed motor control circuit, 18 ... Motor driver, 19 ...
Actuator driver, 20, 30 ... Servo on / off switch, 21 ... Focus servo equalizer (EQ), 22 ... Focus actuator driver, 23, 57 ... Lens drive signal generating circuit, 24 ... Disk motor Control circuit, 25 ...
Disk motor driver, 26 ... Signal processing circuit, 27 ... Correction RAM, 28 ... MPEG video decoder and audio decoder circuit, 29
... System controller, 31 ... Low-pass filter LPF, 32 ... High-pass filter HP
F, 33 ... Window comparator, 34 ...
・ Polarity comparator, 35 ・ ・ ・ Switch, 40 ・
..Analog-digital (AD) converters, 41 ... T
E data, 42 ... FE data, 43 ...
Digital tracking servo control circuit, 44 ...
Digital feed motor control circuit, 45, 46, 47 ...
-Digital-analog (DA) converter, 50 ... Digital focus servo equalizer (EQ), 51, 5
6 ... Selector, 52 ... Digital LPF,
53 ... Digital HPF, 54 ... Window comparator, 55 ... Standby register,
58, 60 ... Timer circuit, 59 ... Mute switch.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-9-326123 (JP, A) JP-A-3-25729 (JP, A) JP-A-9-50630 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G11B 7/085

Claims (8)

(57) [Claims] 1. A focus error detecting means for detecting a focal point of a beam spot based on a signal read from a disc via an optical pickup, and a differentiating means for outputting a high frequency component of an output of the focus error detecting means. A comparing means for comparing the output level of the focus error detecting means with a preset level; an accelerating means for accelerating the focus lens from the currently reproducing layer to the other layer; the differentiating means and the and accelerating means comprises a summing means for injecting the output to the focus servo of said differentiating means switched according to the result of said comparing means, outputting a low frequency component of the output of the focus error detection unit
Further comprising an integrating means for controlling the movement of the focus servo.
At the same time as operating the output signal with the output of this integration means,
Acceleration means accelerates the focus lens to the other layer,
The output of the differentiating means is changed according to the output of the comparing means.
Injected into the waste servo, the polarity of the output of the differentiating means is reversed
At that point, return the focus servo operation state to normal
Along with the fact that the polarity of the differentiating means is reversed,
Focus that operates the focus servo for a fixed time
The focus servo control device further comprising a mute means for cutting off the output of the equalizer . 2. The focus servo control device according to claim 1, further comprising gate means for ignoring the output of the comparison means for a predetermined time from the start of the layer jump. 3. A disc on which data is recorded on a plurality of recording surfaces is selectively irradiated with a light beam and read from reflected light on a selected recording surface of the plurality of recording surfaces of the disc. A focus servo control device for adjusting the focal position of the light beam to the selected recording surface based on the signal, and the focal position of the light beam and the selected one of the recording surfaces of the plurality of layers. A focus error detector that detects a deviation from a recording surface, a focus servo equalizer that corrects the focus position of the light beam based on the output of the focus error detector, and a system control that controls the operation of the focus servo equalizer. A circuit, a differentiation circuit for outputting a high frequency component of the output of the focus error detector, and a level of the output of the focus error detector. A comparator that outputs an activation signal when the level of the output of the focus error detector exceeds the preset level, and is controlled by the system control circuit. A jump signal generating circuit that generates a control signal that causes the focal position of the light beam to jump from one of the recording surfaces of the plurality of layers to the other; and one of the output of the differentiating circuit and the output of the jump signal generating circuit. a selector for selecting and outputting in response to the output of the comparator, the output of the selector comprises an adder for adding an output of the focus servo equalizer, the low frequency component of the output of the focus error detector Out
The system control circuit, further comprising:
As the input of the focus servo equalizer,
The output of the focus error detector is converted to the output of the integrating circuit.
The output of the jump signal generation circuit
The focus position of the light beam with a control signal from
Jump from one of the recording surfaces of multiple layers to the other
Further, the comparison circuit outputs the activation signal,
After the output of the differentiating circuit is output to the adder,
When the polarity of the output of the branch circuit is reversed,
Activates the position correction operation of the dust servo equalizer.
On the output side of the focus servo equalizer.
Connected and the polarity of the output of the differentiator circuit is reversed
The focus servo equalizer for a specified time
A focus servo control device further comprising a mute circuit for cutting off the output of the iser . 4. A gate circuit connected to the comparator, further comprising a gate circuit for interrupting the output of the comparator from the one of the recording surfaces of the plurality of layers to the other for a predetermined time immediately after the start of the jump. The focus servo control device according to claim 3, wherein 5. The jump signal generation circuit outputs the control signal for a predetermined time immediately after the start of the jump when jumping from one of the recording surfaces of the plurality of layers to the other. The focus servo control device described in. 6. A pickup means for irradiating an optical recording disk with a laser and reading the reflected light, and a focus error detection for detecting the in-focus point of a beam spot based on a signal read from the disk via the pickup means. Means, a differentiating means for outputting a high frequency component of the output of the focus error detecting means, a comparing means for comparing a level of the output of the focus error detecting means with a preset level, and a current reproduction of the focus lens. and accelerating means for accelerating from that layer into the other layer, an addition means for injecting the focus servo output of said differentiating means switched according to the result of said comparing means and said accelerating means and said differentiating means comprises said Output the low-frequency component of the output of the focus error detection means
Further comprising an integrating means for controlling the movement of the focus servo.
At the same time as operating the output signal with the output of the integrating means,
Acceleration means accelerates the focus lens to the other layer,
The output of the differentiating means is changed according to the output of the comparing means.
Injected into the waste servo, the polarity of the output of the differentiating means is reversed
At that point, return the focus servo operation state to normal
And the polarity of the differentiating means is reversed,
Focus servo that operates the focus servo only during
A disc reproducing apparatus further comprising a mute unit for cutting off the output of the equalizer . 7. The disc reproducing apparatus according to claim 6, further comprising gate means for ignoring the output of the comparing means for a predetermined time from the start of the layer jump. 8. A disc on which data is recorded on a plurality of recording surfaces is selectively irradiated with a light beam and read from reflected light on a selected recording surface of the plurality of recording surfaces of the disc. A disc reproducing apparatus for reproducing the data based on the signal, the pickup reading the reflected light, the focal position of the light beam and the plurality of recordings based on the reflected light read by the pickup. A focus error detector that detects a deviation from the selected recording surface among the surfaces, a focus servo equalizer that corrects the focus position of the light beam based on the output of the focus error detector, and the focus servo System control circuit for controlling the operation of an equalizer, and a differentiation circuit for outputting a high frequency component of the output of the focus error detector A comparator that compares the level of the output of the focus error detector with a preset level, and outputs an activation signal when the output level of the focus error detector exceeds the preset level; A jump signal generation circuit that is controlled by the system control circuit and that generates a control signal that causes the focus position of the light beam to jump from one of the recording surfaces of the plurality of layers to the other; and an output of the differentiating circuit and the jump signal. A selector for selecting and outputting any one of the outputs of the generating circuit according to the output of the comparator; and an adder for adding the output of the selector to the output of the focus servo equalizer , wherein the focus error Output the low frequency component of the output of the detector
The system control circuit, further comprising:
As the input of the focus servo equalizer,
The output of the focus error detector is converted to the output of the integrating circuit.
The output of the jump signal generation circuit
The focus position of the light beam with a control signal from
Jump from one of the recording surfaces of multiple layers to the other
Further, the comparison circuit outputs the activation signal,
After the output of the differentiating circuit is output to the adder,
When the polarity of the output of the branch circuit is reversed,
Activates the position correction operation of the dust servo equalizer.
On the output side of the focus servo equalizer.
Connected and the polarity of the output of the differentiator circuit is reversed
The focus servo equalizer for a specified time
A disk reproducing device further comprising a mute circuit for cutting off the output of the iser .