JPH1196562A - Optical information recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an information recording and reproducing device capable of generating an on-track signal and an off-track signal by eliminating the frequency component of an offset. SOLUTION: Since this optical information recording and reproducing device is provided with an optical pickup 2, a thread motor 4, photodiodes 21 and an on-track signal and off-track signal forming means 20 which at the time of obtaining the on-track signal or the off-track signal of a beam by successively obtaing one envelope signal every time of the traversing of a track of an optical pickup 2 from the modulation signal outputted by the photodiodes 21 and by comparing the envelope signal with a prescribed reference value, generates an output signal contered at the reference value with respect to the envelope signal by passing a high frequency component with a prescribed cutoff frequency, it is made possible to eliminate a low frequency component by the offset from the envelope signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus used for recording data on an optical disk such as a compact disk (CD) using a light beam.

[0002]

2. Description of the Related Art With the development of multimedia oriented to the advanced information society, there is a demand for higher performance and larger capacity of optical discs. Due to its function and purpose of use, this optical disc is a read-only optical disc that only reproduces information data recorded during disc cutting, a write-once optical disc that can be recorded once and cannot be rewritten, and a rewritable optical disc that can be rewritten many times. Can be roughly divided into three types.

[0003] Among them, in particular, in a rewritable optical disk capable of rewriting information data, since a large capacity is required, the information data is written only in a groove portion formed by a spiral groove on the optical disk surface. Since the required recording capacity cannot be satisfied only by the groove recording method for recording, a land / groove recording method for recording information data in a portion called a land portion between the groove portions is adopted. Was.

That is, in order to record information data on a predetermined track on an optical disk in an optical disk recording / reproducing apparatus, an optical pickup is moved onto a target track of the optical disk and a laser beam is irradiated onto the target track. There must be. For this purpose, it is necessary to position the optical pickup at the target position. There is a seek servo system as a servo system for moving an optical pickup to a target position in a radial direction of an optical disk. In the seek servo system, a system controller supplies a coarse feed command to a thread servo circuit based on a host computer. The optical pickup reads the information signal of the current position from the optical disk,
The RF amplifier circuit, the focus error detection circuit, and the tracking error detection circuit receive the RF signal through the adder and the subtractor.
It supplies a signal, an addition signal and a subtraction signal. The tracking error detection circuit generates a tracking error signal from the difference signal and supplies it to the thread servo circuit. The sled servo circuit generates a drive signal based on the tracking error signal, and supplies the drive signal to the sled motor. The sled motor causes the optical pickup to perform a coarse seek operation via a coarse feed mechanism (not shown) based on the drive signal.

[0005] The operation of the seek servo system is composed of two parts, a sled motor system and an actuator system in the optical pickup. The sled motor system performs the coarse seek operation of the optical pickup by the sled motor, and detects and positions the position by an encoder (not shown). The actuator system causes the optical pickup to perform a fine seek operation by a two-axis actuator using a tracking coil (not shown).

The operation sequence of the seek servo system will be described below. First, the coarse seek operation is performed up to the vicinity of the target track position. Even if a coarse seek is performed and the optical pickup stops near the target address, the movable part of the actuator in the optical pickup does not stop immediately, but vibrates and stops after waiting for a predetermined settling time.

Next, a track pull-in operation is performed to read the reached address information. Here, the execution of the track pull-in operation at the time when the track eccentric speed is high is likely to cause a pull-in error, so this operation is waited until the eccentric speed approaches zero.

When the laser beam tracks the track, the tracking coil is driven by the drive signal from the tracking servo circuit, the track is tracked on track, the address is read, and the difference from the target address is obtained. We do a minute seek for that much. At this time, the optical pickup reads the information signal of the current position from the optical disk and supplies it to the tracking error detection circuit.

The tracking servo system comprises a tracking coil and a tracking servo circuit of the actuator system in the optical pickup. The actuator system causes the optical pickup to perform a fine tracking operation by, for example, a two-axis actuator.

[0010] Then, the laser beam tracks the track, performs tracking, reads an address, and knows the difference from the target address to perform a fine seek by that amount. At this time, if the eccentric speed is high, it is difficult to perform seek control stably, so wait until the eccentric speed decreases, finally reach the target track, and land on the optical disc between the groove portions. The recording operation is performed by a land / groove recording method for recording information data on the recording medium.

However, when an on-track signal and an off-track signal are obtained in a seek servo system, the degree of modulation of the signal and the offset of the signal change due to the power of the laser beam, the offset of the optical sensor, etc. In some cases, the on-track signal and the off-track signal cannot be accurately obtained, or in the worst case, the determination becomes impossible. As a circuit for removing such an offset, there has been a circuit that uses a top hold circuit to subtract a change in the peak of the offset from an RF signal.

A low-frequency component including a defect signal generated by a defect such as a scratch or a fingerprint on an optical disk is detected by a peak hold circuit determined by a time constant, and the low-frequency component is converted into a fluctuation component by an HPF. Japanese Patent Laid-Open No. 1-92972 discloses a defect detection circuit which compares the obtained fluctuating low-frequency component with a detection level using a comparator and obtains defect information to remove a signal component that continues for a long time. ing.

The envelope of the reproduced signal is extracted by a peak hold in an envelope extraction circuit, and compared with a reference signal in a comparison circuit. Whether the cause of the failure in tracing the disk is mechanical vibration or a scratch on the disk. Is disclosed in Japanese Patent Application Laid-Open No. 62-273663.

[0014]

However, in the above-described conventional disk reproducing apparatus, a peak hold circuit or a bottom hold circuit is used for generating an on-track signal and an off-track signal. It has to be changed, and it is difficult to determine the time constant. Also, depending on the state of the recording medium, the drive system, or the optical sensor, the frequency component of the offset is different, so that the offset cannot be removed by the conventional offset removal method, and the envelope signal deviates from the reference value. There is a disadvantage that the track and off-track cannot be distinguished, and the initial state of the tracking error signal cannot be determined.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has a simple configuration and can generate an on-track signal and an off-track signal by removing an offset frequency component. The purpose is to provide the device.

[0016]

An optical information recording / reproducing apparatus according to the present invention comprises a light irradiating means for irradiating a light beam by an optical system onto an optical recording medium on which optically recordable tracks are arranged in parallel. Moving means for moving the light irradiating means in a direction crossing the track and positioning the light irradiating means at a target track position; and reflecting light or transmitted light of the light beam modulated by the light irradiating means crossing the track. A light detecting means having a light receiving section for detecting and outputting as a modulation signal; and an envelope signal generating means for sequentially obtaining one envelope signal from the modulation signal output by the light detecting means for each traversal of the track by the light irradiation means. Means for comparing the envelope signal with a predetermined reference value to obtain an on-track signal or an off-track signal of the beam An optical information recording / reproducing apparatus comprising: a high-pass means for passing an envelope signal through a high-frequency component at a predetermined cut-off frequency to generate an output signal centered on the reference value. Is provided.

According to the optical information recording / reproducing apparatus of the present invention, the following operations are performed. The cutoff frequency is set so that the envelope signal generating means extracts only the envelope signal from the modulated signal. The envelope signal generating means is set to a cutoff frequency at which this frequency component passes, corresponding to the frequency of the envelope signal. In the envelope signal generating means, the signal component recorded on the optical recording medium is removed, and only the envelope which appears when the light detecting means crosses the track is taken out. Therefore, the cut-off frequency of the envelope signal generating means is set to a frequency at which only the envelope signal passes without passing the signal component recorded on the optical recording medium. The cut-off frequency of the envelope signal generating means is variably set in accordance with the read speed of the recording signal component and the frequency of the envelope signal. The envelope signal extracted by the envelope signal generating means is supplied to the high-pass means.

In the high-pass means, the offset of the low-frequency component generated by the state of the optical recording medium, the light irradiating means, the moving means or the light detecting means is cut off, and a signal swinging around the reference value is output. Is set to the cutoff frequency. The high-pass means uses the change in the envelope signal to warp the optical recording medium in the cross-track direction,
In order to remove the change due to the offset or the like of the light detection means, corresponding to the frequency of the change of the offset in advance,
The cut-off frequency is set so as to pass this frequency component.

Since the modulation signal has a low frequency component vibration due to factors such as warping of the optical recording medium, the high-pass means removes this frequency and generates a signal which swings around the center of the reference voltage. . Since the offset of each device differs depending on the variation of the light detection means, this offset is removed by the high-pass means so as to correspond to each device. Also, in the high-pass unit, when the modulation signal is lost due to a scratch or the like on the optical recording medium, a signal that swings to the reference voltage center is generated so that the center is maintained when the modulation signal returns. .

In order to satisfy such a function, the cutoff frequency of the high-pass means is adjusted so that the offset is removed from the envelope signal in the high-pass means, and the warp of the optical recording medium in the cross-track direction and the offset of the light detecting means are reduced. The frequency is set such that a change due to the above is cut off and a signal swinging around the center of the reference voltage is generated. Since the width of signal loss based on factors such as warpage and scratches of the optical recording medium changes according to the reading speed of the recording signal, the cutoff frequency of the high-pass means corresponds to the reading speed of the recording signal. Set variably.

As described above, the envelope signal is extracted by the envelope signal generating means, and the envelope signal is extracted by the high-pass means so that a change due to the offset of the envelope signal due to the state of the optical recording medium or the like can be detected. By setting the respective cut-off frequencies of the generating means and the high-pass means, it is possible to easily cut a change in the speed of the recording / reproducing operation on the optical recording medium and a change in the moving speed of the light detecting means. The off frequency can be set. The high-pass means removes the change due to the offset of the envelope signal due to the state of the optical recording medium or the like, and the signal generated so as to swing to the center of the reference voltage is supplied to one input terminal of the comparison means. A reference voltage is supplied to the other input terminal of the comparison means.

An on-track signal and an off-track signal are generated by the comparing means depending on whether the reference value is larger or smaller. In the comparing means, a high-level off-track signal is generated when a signal swinging around the center of the reference voltage output from the high-pass means is larger than a reference value, and a low-level on-track signal is generated when the signal is small. By using the on-track signal and the off-track signal, the number of traversed tracks can be counted to perform an operation such as a track jump.

[0023]

Embodiments of the present invention will be described below. The optical disk to which this embodiment is applied is, for example, a compact disk (CD). There are several families of CDs, including a read-only CD-ROM and a CD-R that can be written only once. Next, a configuration of the present embodiment applied to such an optical disk will be described. FIG. 1 is a block diagram showing a configuration of an optical disk recording / reproducing apparatus according to the present embodiment. First, the configuration of the optical disk recording / reproducing apparatus will be described. The optical disk recording / reproducing apparatus of the present embodiment includes an optical disk rotation drive control system, a coarse feed drive control system, a servo control circuit 5 for controlling respective servo systems of an optical pickup control system, and an optical pickup 2.
A laser control circuit 6 for controlling the laser power supplied to the laser beam; an IV conversion matrix circuit 8 for obtaining a reproduction RF signal, a focus error signal and a tracking error signal from the reflected light of the laser; and a signal control circuit 7.

The optical disk rotation drive control system includes a spindle servo circuit 9, a spindle motor 3, and the optical disk 1. Here, the optical disk 1 constitutes a recording medium. The coarse feed drive control system includes a thread servo circuit 10.
And a thread motor 4. The optical pickup control system includes an optical pickup 2, an IV conversion matrix circuit 8, a focus servo circuit 11, a tracking servo circuit 12, and a laser control circuit 6. Here, the IV conversion matrix circuit 8 includes a photodiode 21 for detecting the reflected light of the laser on the two-divided surface, an adder 22 for adding the two-divided signal, and a subtractor 23 for subtracting the two-divided signal. An RF amplification circuit 24 that amplifies the reproduction RF signal from the output of the adder 22 and supplies a servo signal to the thread servo circuit 10; a focus error detection circuit 25 that detects a focus error signal from the output of the subtractor 23; And a tracking error detection circuit 26 for detecting a tracking error signal from the output of the reference numeral 23. Further, the laser control circuit 6 includes a PWM driver 14 that performs pulse width modulation on the laser light, and a laser diode 13 that emits the laser light.

The signal control circuit 7 includes a system controller 19 for controlling each part of the apparatus, an ECC encoding circuit 16 for adding an error correction code to the recording data by a Reed-Solomon product code, and a recording data to which the error correction code is added. Modulation circuit 15 that performs 8/14 modulation by EFM
A demodulation circuit 17 for 8/14 demodulating the reproduction data by EFM and supplying a servo signal to the spindle servo circuit 9; and an ECC decoding circuit 18 for performing error correction processing on the reproduction data by Reed-Solomon product code and outputting the reproduction data. And Here, in this example, in particular, the system controller 19 extracts the envelope signal from the modulated signal from the RF amplification circuit 24, removes the offset of the envelope signal, and generates a signal centered on the reference value.
An on-track signal and an off-track signal are generated depending on whether the value is larger or smaller than a reference value, and the number of tracks crossed is counted using the on-track signal and the off-track signal to perform an operation such as a track jump. It has a possible on-track signal and off-track signal generation means 20.

Next, the connection relationship of the optical disk recording / reproducing apparatus will be described. First, the connection relationship of the optical disk rotation drive control system will be described. The spindle servo circuit 9 is a spindle motor 3
, And the spindle motor 3 is connected to the optical disk 1 via a rotation mechanism. Next, the connection relationship of the coarse feed drive control system will be described. The thread servo circuit 10 is connected to a thread motor 4, and the thread motor 4 is connected to an optical pickup 2 of an optical pickup control system via a coarse feed mechanism.

Next, the connection relationship of the optical pickup control system will be described. The optical pickup 2 is an IV conversion matrix circuit 8
Of the photodiode 2
The two divided outputs of 1 are connected to an adder 22 and to a subtractor 23. The adder 22 and the subtractor 23 are connected to an RF amplifier circuit 24, and have a focus error detection circuit 25 and a tracking error detection circuit 26. Connected.

The focus error detection circuit 25 and the tracking error detection circuit 26 are connected to the focus servo circuit 11 and the tracking servo circuit 12, and the focus servo circuit 11 and the tracking servo circuit 12 Connected to tracking coil.

Next, the connection relation of the signal processing system will be described. RF
The amplification circuit 24 is connected to the demodulation circuit 17 of the signal control circuit 7 and the on-track signal and off-track signal generation means 20, and the demodulation circuit 17 is connected to the ECC decode circuit 18. The ECC encoding circuit 16 is a modulation circuit 15
The modulation circuit 15 is connected to the PW of the laser control circuit 6.
The PWM driver 14 is connected to the laser diode 13. The laser diode 13 is provided to the optical pickup 2 so as to form a predetermined laser beam.

Here, in this example, particularly, the on-track signal and off-track signal generation means 20 is an
The cutoff frequency of F is set so that only the envelope signal is extracted from the modulation signal, and the cutoff frequency of HPF is cut off by the offset of the low frequency component generated by the state of the optical disk, optical pickup, thread motor or photodiode. To output a signal that swings to the center of the reference value, and further generates an on-track signal and an off-track signal depending on whether the reference value is large or small, and traverses using the on-track signal and the off-track signal. It has a function of counting the number of tracks and performing an operation such as a track jump. Also,
On-track signal and off-track signal generation means 20
The thread servo circuit 10 may be provided.

The optical disk recording / reproducing apparatus is connected to a host computer via a system controller 19 and an interface circuit (not shown).

The operation of the optical disk recording / reproducing apparatus thus configured will be described. When recording or reproducing an information signal with respect to an optical disk recording / reproducing apparatus according to a command from a host computer (not shown), the optical pickup 2 is sought by a thread motor 4 to a target track position on the optical disk 1 from the host computer. After positioning, the tracking servo circuit 12 and the focus servo circuit 11 drive the tracking coil and the focus coil to finely adjust the tracking and the focus to match the target value.

At the time of recording, the laser control circuit 6 sets the laser power in advance to the erase power level to erase the information in the portion not to be recorded, and adjusts the laser power to the write power level to record the information signal at the target track position. At the time of reproduction, the laser power is adjusted to the read power level by the laser control circuit 6 to reproduce the information signal recorded at the target track position.

In the signal control system, first, the system controller 10 supplies a rotation command to the spindle servo circuit 9 of the servo control circuit 5 based on the host computer. The spindle servo circuit 9 supplies a drive signal to the spindle motor 3 according to this command, and rotates the spindle motor 3. Play R
A servo signal synchronously detected from the demodulation circuit 17 based on the F signal is supplied to the spindle servo circuit 9.

Next, the system controller 19 supplies a command of a coarse feed command to the thread servo circuit 10 based on the host computer. The optical pickup 2 reads the information signal of the current position from the optical disc 1 and, via a photodiode 21, an adder 22, and a subtractor 23, an RF amplifier circuit 24, a focus error detection circuit 25
The RF signal, the addition signal, and the subtraction signal are supplied to the tracking error detection circuit 26. The tracking error detection circuit 26 generates a tracking error signal from the difference signal and supplies the signal to the thread servo circuit 10. The thread servo circuit 10 generates a drive signal based on the tracking error signal, and supplies the drive signal to the thread motor 4. The sled motor 4 causes the optical pickup 2 to perform a coarse seek operation via a coarse feed mechanism (not shown) based on the drive signal.

The operation of the seek / servo system includes two systems: a sled motor 4 system and an actuator system in the optical pickup 2. The thread motor 4 system causes the optical pickup 2 to perform a coarse seek operation by the thread motor 4,
The position is detected by an encoder (not shown). The actuator system includes an optical pickup 2 using a biaxial actuator using a tracking coil (not shown).
The fine seek operation.

The operation sequence of such a seek servo system will be described below. First, the coarse seek operation is performed up to the vicinity of the target track position. Even if the coarse pickup is performed and the optical pickup 2 stops near the target address, the movable part of the actuator in the optical pickup 2 does not stop immediately, but vibrates and stops after a predetermined settling time.

Next, a track pull-in operation is performed to read the reached address information. Here, the execution of the track pull-in operation at the time when the track eccentric speed is high is likely to cause a pull-in error, so this operation is waited until the eccentric speed approaches zero.

At this time, the on-track signal / off-track signal generating means 20 sets the cut-off frequency of the LPF to be described later so as to extract only the envelope signal from the modulation signal, and sets the cut-off frequency of the HPF to the optical disk, the optical pickup, and the like. , Set to output a signal that swings to the center of the reference value by cutting off the offset of the low frequency component generated by the state of the thread motor or the photodiode, and furthermore, determines whether the on-track signal is larger or smaller than the reference value. , Generate an off-track signal. Using the on-track signal and the off-track signal, the system controller 19 can perform the track jump operation by counting the number of tracks crossed by the traverse operation. At this time, the optical pickup 2 reads the information signal of the current position from the optical disc 1 and supplies it to the tracking error detection circuit 26. Then, the laser beam tracks the track, and the tracking servo circuit 1
The tracking coil is driven by the drive signal from 1 to perform tracking on track, read an address, and know the difference from the target address, and perform a fine seek by that much.

That is, the photodiode 21 receives the laser beam reflected by the optical disk 2 on the two-divided surface. The photodiode 21 converts the received split laser light into an electric signal and supplies the electric signal to the subtracter 23. The subtractor 23
The difference signal is generated by subtracting the divided signal. The tracking error detection circuit 26 detects a tracking error signal from the difference signal and supplies the signal to the tracking servo circuit 12.
The tracking servo circuit 12 performs tracking of the optical pickup 2 by a tracking coil of a two-axis actuator (not shown) based on a tracking error signal. The focus error detection circuit 25 detects a focus error signal from the information signal and supplies the focus error signal to the focus servo circuit 11. The focus servo circuit 11 performs focusing of the optical pickup 2 by a focus coil of a two-axis actuator (not shown) based on a focus error signal.

Also at this time, if the eccentric speed is high, it is difficult to perform seek control stably. Therefore, it waits until the eccentric speed decreases, finally reaches the target track, and executes the recording or reproducing operation.

After positioning the optical pickup 2 at the target track position, the recording or reproducing operation is performed as follows. At the time of reproduction, the system controller 19 supplies a reproduction command to the PWM driver 14 of the laser control circuit 6. The PWM driver 14 adjusts the laser emission power to the reproduction power level, and
Supply 3 The laser diode 13 irradiates the optical disc 1 with laser light via a lens. The photodiode 21 receives the laser beam reflected by the optical disk 2 on a split surface. The photodiode 21 converts the received split laser light into an electric signal and supplies the electric signal to the adder 22. The adder 22 adds the two divided signals to generate a reproduced RF signal.

The reproduced RF signal is supplied to an RF amplifier circuit 24. The RF amplifier 24 amplifies the reproduced data at a high frequency and supplies the amplified data to the demodulator 17. The demodulation circuit 17 converts the reproduced data into E
8/14 demodulation by FM. The demodulation circuit 17 supplies the demodulated reproduced data to the ECC decoding circuit 18. E
The CC decode circuit 18 performs error correction processing on the reproduced data by using a Reed-Solomon product code and outputs the reproduced data. The decoded information signal is supplied to a host computer.

At the time of recording, the system controller 19
Supplies a recording command to the PWM driver 14 of the laser control circuit 6. The recording data supplied from the host computer is supplied to the ECC encoding circuit 16. The ECC encoding circuit 16 adds an error correction code to the recording data using a Reed-Solomon product code. EC
The C encoding circuit 16 supplies the recording data added with the error correction code to the modulation circuit 15. Modulation circuit 15
EFM records data to which an error correction code has been added.
Performs 8/14 modulation. The modulation circuit 15 transmits the modulated recording data to the PWM driver 1 of the laser control circuit 6.
4 The PWM driver 14 pulse width modulates the 8/16 modulated recording data based on the recording command, and supplies the laser diode 13 with a laser power signal of a write power level. The laser diode 13 irradiates the optical disc 1 with laser light via a lens. The recording data is recorded at the target track position in a state where the recording thin film of the optical disc 1 is heated by the laser beam and becomes amorphous.

In this embodiment, particularly, when a track jump is performed at the time of recording or reproduction, the on-track signal and off-track signal generation means 20 use the L to be described later.
The cutoff frequency of the PF is set so that only the envelope signal is extracted from the modulation signal from the RF amplifier circuit 24, and the cutoff frequency of the HPF is set to a low frequency component generated by the state of the optical disk, optical pickup, thread motor, or photodiode. Is set to output a signal that swings around the reference value by cutting off the offset amount, and further generates an on-track signal and an off-track signal depending on whether the reference value is larger or smaller, and generates an on-track signal and an off-track signal. The number of tracks crossed is counted by using an off-track signal, and an operation such as a track jump can be performed. That is, the on-track signal and off-track signal generation means 20 is basically used to count how many tracks have traversed (traverse) when performing a track jump at the time of reproduction. It is used to detect a track to be recorded, to return to that track when a recording error occurs, or to move to a track to start recovery.

The configuration of the on-track signal and off-track signal generating means of this embodiment of the optical disk recording / reproducing apparatus configured and operating as described above will be described with reference to FIGS. As shown in FIG. 2, the on-track signal and off-track signal generating means generates an envelope signal S2 shown in FIG. 3B from the modulation signal S1 shown in FIG. 3A from the RF amplifier circuit 24 to an intermediate value of the modulation signal S1. An LPF 27 having a cut-off frequency set so as to take out only
FIG. 3C which swings around the reference value Vth by blocking the offset of the low frequency component generated by the state of the optical disk, the optical pickup, the sled motor or the photodiode.
And an on-track signal and an off-track signal as a comparator output signal S4 shown in FIG. 3D are generated based on whether the cut-off frequency is set so as to output the HPF output signal S3 shown in FIG. do it,
A comparator 29 configured to count the number of tracks crossed using the on-track signal and the off-track signal and perform an operation such as a track jump;
Is configured.

Here, the LPF 27 converts the modulated signal S1 shown in FIG. 3A to an intermediate value of the modulated signal S1 in FIG. 3B.
In order to extract only the envelope signal S2 shown in (1), a cut-off frequency for passing this frequency component is set in advance corresponding to the frequency of the envelope signal S2. The frequency of the envelope signal S2 is determined by the moving speed of the optical pickup 2 when traversing. For example, in the case of a CD-ROM, 30 KHz at 1 × speed
50KHz, 250KHz-300K at double speed or higher
Hz. The LPF 27 has a function of extracting a change in the frequency of the envelope signal S2. If the envelope signal S2 does not have a sufficient amplitude to perform the subsequent signal processing, the LPF 27 may be configured to have a gain or an amplifier may be provided at the subsequent stage.

The HPF 28 removes a change in the envelope signal S2 shown in FIG. 3B from the change in the radial direction (track traversal direction) of the optical disc and the change due to the offset of the photodiode in advance. The cutoff frequency at which this frequency component passes is set corresponding to the minute frequency. The frequency of the offset change is determined by the rotation speed of the optical disc 1. For example, about 200 to 50 at 1x speed
It is measured at about 0 rpm.

As described above, the LPF 27 extracts the envelope signal S2 shown in FIG.
The envelope signal S depending on the state of the optical disk, etc.
By setting the cutoff frequency of each of the LPF 27 and the HPF 28 so that the change due to the offset of 2 can be detected, the change in the speed of the recording / reproducing operation on the recording medium and the movement of the photodiode in the optical pickup are performed. The cutoff frequency can be easily set for the change in speed by detecting the above-described frequencies.

Specifically, the LPF 27 extracts only the envelope signal S2 component shown in FIG. 3B of the modulation signal S1 shown in FIG. 3A, that is, removes the signal component recorded on the optical disk, and the photodiode detects the track. It has the function of extracting only the envelope signal S2 that appears when it crosses. Therefore, the cutoff frequency fc1 of the LPF 27 is set to a frequency that allows only the envelope signal S2 to pass without passing the signal component recorded on the optical disc. The cutoff frequency fc1 of the LPF 27 is variably set in accordance with the read speed of the recording signal component and the frequency of the envelope signal S2.

FIG. 4 is a circuit diagram showing a configuration example of the LPF 27. FIG. 4A shows a first-order positive filter as a first LPF, in which one end of a resistor 41 is connected to an input terminal 40, the other end of the resistor 41 is connected to an output terminal 43, and one end of a capacitor 42. And the other end of the capacitor 42 is connected to ground.

FIG. 4B shows a first-order negative feedback active filter as a second LPF.
The input terminal 44 is connected to one end of a resistor 45,
The other end of 5 is connected to the non-inverting input terminal (+) of the operational amplifier 48 while being connected to the other end of the capacitor 46 and the resistor 47, one end of which is connected to the ground, and the inverting input terminal (-) of the operational amplifier 48. Is connected to the other end of a resistor 51 whose one end is connected to the ground, and is connected to the other end of a resistor 49 and a capacitor 50 each having one end connected to an output terminal and an output terminal 52 of an operational amplifier 48, respectively. .

FIG. 4C shows a primary active filter as a third LPF.
, And the inverting input terminal (−) of the gm amplifier 54 is connected to the ground. The output terminal of the gm amplifier 54 is connected to the other end of the capacitor 55 whose one end is connected to the ground and to the non-inverting input terminal (+) of the operational amplifier 56. The output terminal of the operational amplifier 56 is connected to the output terminal 57 and the operational amplifier 56.
And the inverting input terminal (−) of the gm amplifier 54 is fed back. Here, the gm amplifier 54 stores and stores a charge in a capacitor, and inputs and outputs a current by itself. Gm is a constant indicating an amplification factor of a signal source and the like.

By combining such an LPF 27, the primary and secondary cutoff frequencies can be varied in the case of a positive filter by varying the values of the capacitor and the resistor, and in the case of the active filter, the current value of the active filter can be varied. Thus, a plurality of current values are set in advance, and the current is appropriately switched to make the cutoff frequency variable.

Returning to FIG. 2, the HPF 28 removes, from the envelope signal S2, the amount of warpage in the radial direction of the optical disk or a change due to the offset of the photodiode from the envelope signal S2. Since it has a vibration component of a frequency component, it has a function of removing this frequency and generating an HPF output signal S3 shown in FIG. 3C swinging around the reference voltage Vth. Here, the offset of each optical disk recording / reproducing device is different due to the variation of the photodiode.
Has a function of removing this offset corresponding to each device. When the modulation signal S1 shown in FIG. 3A is lost due to a scratch on the optical disk or the like, the HPF 28 outputs an HPF output signal S3 swinging around the center of the reference voltage Vth so as to maintain the center when the modulation signal S1 returns. Has the function of generating

To satisfy such a function, the HPF 28
The cutoff frequency fc2 removes an offset from the envelope signal S2, cuts off a change due to a radial warp of the optical disk, an offset of the photodiode, etc., and generates an HPF output signal S3 swinging around the center of the reference voltage Vth. It is set to such a frequency. Also,
Since the width of the signal drop due to the warp of the optical disc or a factor such as a scratch changes according to the reading speed of the recording signal,
The cutoff frequency fc2 of the HPF 28 is variably set in accordance with the read speed of the recording signal.

In the case of a positive filter, the HPF 28 is replaced with a capacitor and a resistor in correspondence with the LPF 27 shown in FIG. The cutoff frequency can be set to a plurality of values by setting the current value of the active filter, and the cutoff frequency is made variable by appropriately switching the current.

The comparator 29 detects the swing of the HPF shown in FIG.
When the output signal S3 is larger than the reference value Vth, an off-track signal is generated as a high-level (H) comparator output signal shown in FIG. 3D, and when the output signal S3 is low, a low-level (L) comparator output signal shown in FIG. 3D is generated. A function of generating an on-track signal, counting the number of tracks crossed using the on-track signal and the off-track signal, and performing an operation such as a track jump.

Here, when the signal of the optical disk is not read out, or when the optical pickup is completely on-track, the envelope signal S2 does not appear, so that the HPF output signal S
3 matches the reference voltage Vth. At this time, the initial values of the on-track signal and the off-track signal cannot be determined. In the worst case, a state like oscillation may occur, and to avoid this, the reference voltage V
th is given a reference voltage offset ± α.
The reference voltage offset ± α is set to a small value that does not affect the discrimination between the on-track signal and the off-track signal. Thereby, the initial value of the comparator output signal S4 can be determined to be high level or low level. The above-mentioned reference voltage offset ± α is set to about 500 mV.

The operation of the on-track signal and off-track signal generating means of the present embodiment thus configured is shown in FIG.
This will be described with reference to FIG. As shown in FIG. 2, the modulation signal S1 shown in FIG. 3A from the RF amplification circuit 24 is supplied to the on-track signal and off-track signal generation means. L
The cutoff frequency is set in the PF 27 so that only the envelope signal S2 shown in FIG. 3B is extracted from the modulation signal S1 shown in FIG. 3A from the RF amplifier circuit 24.

Since the LPF 27 extracts only the envelope signal S2 shown in FIG. 3B of the modulation signal S1 shown in FIG. 3A, the LPF 27 cuts off this frequency component in advance corresponding to the frequency of the envelope signal S2. The frequency is set. Accordingly, the LPF 27 extracts a change in the frequency of the envelope signal S2.
If the envelope signal S2 does not have a sufficient amplitude to perform the subsequent signal processing, the envelope signal S2 is amplified by a gain provided in the LPF 27, or is amplified by a subsequent amplifier.

Specifically, in the LPF 27, FIG.
3B of the modulated signal S1 shown in FIG.
Only two components are removed. That is, the signal component recorded on the optical disk is removed, and only the envelope signal S2 that appears when the photodiode crosses the track is extracted. Therefore, the cutoff frequency fc1 of the LPF 27 is set to a frequency at which only the envelope signal S2 passes without passing the signal components recorded on the optical disc. The cutoff frequency fc1 of the LPF 27 is variably set in accordance with the read speed of the recording signal component and the frequency of the envelope signal S2. The primary and secondary cutoff frequencies of the LPF 27 are set to a plurality of current values by setting the current value of the active filter, and the cutoff frequency is made variable by appropriately switching the current values. By using the LPF 27, the extracted envelope signal S2 becomes the modulated signal S1
, And the frequency of the envelope signal S2 to be extracted can be easily extracted by setting the cutoff frequency. The envelope signal S2 extracted by the LPF 27 is supplied to the HPF 28.

The HPF 28 cuts off the offset of the low frequency component generated by the state of the optical disk, the optical pickup, the sled motor or the photodiode, and outputs the HPF output signal S3 shown in FIG. The cutoff frequency is set as follows. Further, the HPF 28 removes a change due to a radial direction (track crossing direction) of the optical disc and a change due to an offset of the photodiode from the change of the envelope signal S2 shown in FIG. 3B. Is set to a cutoff frequency at which this frequency component passes.

Further, in the HPF 28, a change due to a radial warp of the optical disk, an offset of the photodiode, or the like is removed from the envelope signal.
That is, since the modulation signal S1 shown in FIG. 3A has a low frequency component vibration due to factors such as warpage of the optical disc, the HPF 28 removes this frequency and swings around the reference voltage Vth in the HPF 28 shown in FIG. 3C. An output signal S3 is generated. Here, since the offset of each optical disk recording / reproducing device differs due to the variation of the photodiode, the offset is removed in the HPF 28 so as to correspond to each device. In the HPF 28, when the modulation signal S1 is lost due to a scratch on the optical disc or the like, the center of the reference voltage Vth swings so that the center is maintained when the modulation signal S1 returns.
A PF output signal S3 is generated. Here, the modulation signal S1
Is converted into an envelope signal S2 having an intermediate value of the modulation signal S1 by passing through the LPF 27. Therefore, the envelope signal S2 is obtained by removing a low-frequency component from the envelope signal S2 by passing through the HPF 28 and setting the voltage at the center of the intermediate value. HP swinging around the voltage Vth shown in FIG. 3C
The F output signal S3 can be easily generated.

To satisfy such a function, the HPF 28
The cut-off frequency fc2 of FIG.
The offset is removed from the envelope signal S2 shown in FIG. B, and the variation due to the radial warpage of the optical disc or the offset of the photodiode is cut off, and the frequency at which the HPF output signal S3 swinging around the center of the reference voltage Vth is generated. Is set to In addition, the width of the signal loss based on factors such as the warp and scratches of the optical disc changes according to the read speed of the recording signal, so that the cutoff frequency fc2 of the HPF 28 is variably set according to the read speed of the recording signal. Is set. Such a HPF 28 is also constructed by replacing a capacitor and a resistor in the case of a positive filter in correspondence with the LPF 27 shown in FIG.
In the case of an active filter, the primary and secondary cutoff frequencies are set to a plurality of current values by setting the current values of the active filter, and the cutoff frequency is made variable by appropriately switching the current.

As described above, the LPF 27 extracts the envelope signal S2 shown in FIG.
The envelope signal S depending on the state of the optical disk, etc.
By setting the respective cutoff frequencies of the LPF 27 and the HPF 28 so as to detect the change due to the offset of 2, the change in the speed of the recording / reproducing operation on the optical disk and the movement of the photodiode in the optical pickup are performed. The cutoff frequency can be easily set for the change in speed by detecting the above-described frequencies. The HPF 28 removes the change due to the offset of the envelope signal S2 due to the state of the optical disk or the like, and the signal generated so as to swing around the reference voltage Vth is supplied to the non-inverting input terminal (+) of the comparator 29. The reference voltage Vth is supplied to the inverting input terminal (-) of the comparator 29.

The comparator 29 generates an on-track signal and an off-track signal as the comparator output signal S4 shown in FIG. 3D depending on whether the reference value Vth is larger or smaller than the reference value Vth. An operation such as a track jump can be performed by counting the number of tracks that have been moved. Comparator 29
3C, the HPF output signal shown in FIG. 3C which swings around the center of the reference voltage Vth output from the HPF 28 is the reference value Vth
On the other hand, an on-track signal as a comparator output signal S4 shown in FIG. 3D at a high level (H) is generated when the level is large, and an off-track signal as a comparator output signal S4 shown in FIG. 3D at a low level (L) when the level is small. When a signal is generated, the number of tracks crossed is counted using the on-track signal and the off-track signal, and an operation such as a track jump can be performed.

When the high-level (H) on-track signal as the comparator output signal S4 shown in FIG. 3D is supplied to the system controller 19, it is recognized as an on-track state, and the low-level (L) FIG. When the off-track signal as the comparator output signal S4 is supplied, the off-track state is recognized, the number of traversing the track (traverse) is counted, and the track jump operation is performed using the thread servo circuit 10. It can be carried out. Here, when the signal of the optical disk is not read out, or when the optical pickup is completely on-track, the envelope signal does not appear, and the HP signal shown in FIG.
The F output signal S3 matches the reference voltage Vth. At this time, the initial values of the on-track signal and the off-track signal as the comparator output signal S4 shown in FIG. 3D cannot be determined. In the worst case, a state such as oscillation may occur. To avoid this, the reference voltage Vth is provided with a reference voltage offset ± α.
The reference voltage offset ± α is set to a small value that does not affect the discrimination between the on-track signal and the off-track signal as the comparator output signal S4 shown in FIG. 3D. Thereby, the initial value of the output of the comparator can be determined to be high level or low level.

According to the above-described optical information recording / reproducing apparatus of the present embodiment, the optical system irradiates a light beam on the optical disk 1 as an optical recording medium on which optically recordable tracks are arranged in parallel. An optical pickup 2 as a light irradiation means, a sled motor 4 as a moving means for moving the light irradiation means in a direction traversing the track and positioning it at a target track position, and being modulated by the light irradiation means crossing the track A photodiode 21 as a light detecting means having a light receiving portion for detecting a reflected light or a transmitted light of the light beam and outputting the light as a modulation signal, and from a modulation signal S1 outputted by the light detecting means, every time a track of the light irradiation means is traversed. LPF 27 as an envelope signal generation means for sequentially obtaining one envelope signal S2
An optical information recording / reproducing apparatus including a comparator 29 as a comparing means for comparing the envelope signal S2 with a predetermined reference value Vth to obtain an on-track signal or an off-track signal of the beam. On the other hand, the HPF 28 is provided as a high-pass means for generating an output signal centered on the reference value Vth by passing a high-frequency component at a predetermined cutoff frequency. When generating the reference value Vth, the low frequency component of the envelope signal S2 is removed and the reference value Vth is set to a signal centered on the reference value Vth. Track signal,
An off-track signal can be obtained.

Further, according to the optical information recording / reproducing apparatus of the present embodiment, the envelope signal S2 and the signal at the center of the reference value Vth are generated without using a hold circuit such as a peak hold and a bottom hold. LPF
27, since only the cut-off frequency of the HPF 28 is set, there is no difficulty in determining the optimum value of the time constant of the hold circuit with respect to the double speed of the recording / reproducing speed or the speed at which the optical pickup 2 crosses the track. With such a configuration, it is possible to obtain an on-track signal and an off-track signal from which the offset by the optical disc 1 or the like has been removed.

According to the above-described optical information recording / reproducing apparatus of the present embodiment, the reference value Vth is given an offset of the reference value that does not affect the on-track signal and the off-track signal. The initial values of the on-track signal and the off-track signal output from the comparator 29 can be determined.

[0072]

The optical information recording / reproducing apparatus according to the present invention comprises:
A light irradiating means for irradiating a light beam by an optical system onto an optical recording medium on which optically recordable tracks are arranged in parallel, and moving the light irradiating means in a direction crossing the track to position it at a target track position Means of transportation
A light detecting unit having a light receiving unit for detecting reflected light or transmitted light of the light beam modulated by the light irradiating means traversing the track and outputting it as a modulation signal; Envelope signal generating means for sequentially obtaining one envelope signal for each traversal of the track by the light irradiation means from the modulation signal;
A comparison means for comparing the envelope signal with a predetermined reference value to obtain an on-track signal or an off-track signal of the beam; The high-pass means for passing the high-frequency component at the off-frequency and generating an output signal centered on the reference value is provided, so that when the on-track signal and the off-track signal are generated, this reference value is used. By removing the low-frequency component of the envelope signal and making it a signal centered on the reference value, it is possible to obtain an on-track signal and an off-track signal that are not affected by changes in the signal due to an optical disk, a photodiode, or the like. Play.

In the optical information recording / reproducing apparatus according to the present invention, the envelope signal generating means may include:
The cut-off frequency is made variable so that the low-frequency component is passed so that the modulated signal matches the frequency of the envelope signal at a predetermined cut-off frequency. Without using a hold circuit such as a hold, only the cutoff frequency of the envelope signal generation means for generating the envelope signal is set, so when the recording / reproduction speed is double speed or when the optical pickup crosses the track, etc. The difficulty of deciding the optimal value of the time constant of the hold circuit is eliminated, and only the envelope signal can be extracted with a simple configuration that only sets the cut-off frequency of the envelope signal generating means. To get on-track and off-track signals An effect that theft can be.

The optical information recording / reproducing apparatus of the present invention may be arranged such that low frequency components generated by the state of the optical recording medium, the light irradiating means, the moving means or the light detecting means are cut off. Since the cutoff frequency of the high-pass means is made variable,
Without using a hold circuit such as a peak hold or bottom hold, only the cutoff frequency of the high-pass means for generating a signal centered on the reference value is set. Eliminating the difficulty of determining the optimal value of the time constant of the hold circuit with respect to the speed at which the signal crosses the track, the on-track signal from which the offset due to the optical disk or the like has been removed with a simple configuration that simply sets the cutoff frequency of the high-pass means And an off-track signal can be obtained.

In the optical information recording / reproducing apparatus according to the present invention, in the above-mentioned configuration, the comparing means may obtain the initial value of the on-track signal and the off-track signal by using the reference value of the intermediate value of the envelope signal. The on-track signal and the off-track signal output from the comparing means are given by giving a reference value offset that does not affect the on-track signal and the off-track signal as the reference value. This has the effect that the initial value of can be determined.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an optical disc recording / reproducing apparatus according to an embodiment.

FIG. 2 is a block diagram illustrating a configuration of an on-track signal and off-track signal generation unit according to the present embodiment.

3A and 3B are waveform diagrams illustrating the operation of an on-track signal and an off-track signal generation unit according to the present embodiment. FIG. 3A is a diagram illustrating a modulation signal S1, and FIG. 3B is a diagram illustrating an envelope signal S2. FIG. 3C is a diagram showing the output signal S3 of the HPF 28, and FIG. 3D is a diagram showing the output signal S4 of the comparator.

4A and 4B are circuit diagrams illustrating a configuration example of an LPF according to the present embodiment, FIG. 4A is a diagram illustrating a first LPF, FIG. 4B is a diagram illustrating a second LPF, and FIG. FIG. 3 is a diagram showing LPF No. 3;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical disk, 2 ... Optical pickup, 3 ... Spindle motor, 4 ... Thread motor, 5 ... Servo control circuit, 6 ... Laser control circuit, 7 ... Signal control circuit,
8: IV conversion matrix circuit, 9: spindle servo circuit, 10: thread servo circuit, 11: focus servo circuit, 12: tracking servo circuit, 13: laser diode, 14: PWM driver, 15: modulation circuit, 16: ECC encoding circuit, 17 demodulation circuit,
18 ECC decode circuit 19 19 System control circuit 20 On-track signal / off-track signal generation means 21 Photodiode 22 Adder 23
... Subtractor, 24 ... RF amplifier, 25 ... Focus error detection circuit, 26 ... Tracking error detection circuit, S1 ...
Modulation signal, S2: envelope signal, S3: HPF output signal, S4: comparator output signal, 40: input terminal,
41: resistor, 42: capacitor, 43: output terminal, 4
4 input terminal, 45 resistor, 46 capacitor, 47
... resistor, 48 ... op-amp, 49 ... resistor, 50 ... capacitor, 51 ... resistor, 52 ... output terminal, 53 ... input terminal, 54 ... gm amplifier, 55 ... capacitor, 56 ... op-amp, 57 ... output terminal

Claims (4)

[Claims] An optical system for irradiating a light beam on an optical recording medium on which optically recordable tracks are arranged in parallel, and moving the light irradiating means in a direction crossing the tracks. Light detecting means having a moving means for positioning at a target track position, and a light receiving section for detecting reflected light or transmitted light of the light beam modulated by the light irradiating means traversing the track and outputting it as a modulation signal. And an envelope signal generating means for sequentially obtaining one envelope signal every time the light irradiating means traverses the track from the modulated signal output by the light detecting means, and comparing the envelope signal with a predetermined reference value. And a comparison means for obtaining an on-track signal or an off-track signal of the beam. Optical information characterized by providing high-pass means for passing an high-frequency component at a predetermined cutoff frequency with respect to the envelope signal and generating an output signal centered on the reference value. Recording and playback device. 2. The optical information recording / reproducing apparatus according to claim 1, wherein said envelope signal generating means is adapted to adapt to a frequency of said envelope signal at a predetermined cutoff frequency with respect to said modulation signal. An optical information recording / reproducing apparatus characterized in that the cutoff frequency is made variable so as to pass a low frequency component. 3. The optical information recording / reproducing apparatus according to claim 1, wherein a low-frequency component generated by a state of said optical recording medium, said light irradiating means, said moving means or said light detecting means is cut off. An optical information recording / reproducing apparatus, wherein the cutoff frequency of the high-pass means is made variable. 4. The optical information recording / reproducing apparatus according to claim 1, wherein said comparison means obtains an initial value of said on-track signal and said off-track signal by using said reference value of an intermediate value of said envelope signal. An optical information recording / reproducing apparatus characterized in that an offset is added to a value.