JPH10334477A - Disk information reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk information reproducing device capable of generating the envelope signal of a high frequency signal at the crossing of a track by a pickup with high accuracy and accurately measuring a crossing number of tracks by a track counting method. SOLUTION: This disk information reproducing device has a track crossing signal generating circuit 6 for generating a track crossing signal (TCR) being changed in synchronism with the track crossing period of a pickup 3 when the pickup 3 has been moved in the radial direction of a disk 1. The track crossing signal generating circuit 6 has a signal density multiplying means 13 for multiplying the signal density of a high frequency signal and generates the track crossing signal (TCR) based on the envelope signal (EVP) of a high density high-frequency signal (DRF) generated by the means 13 and a tracking error signal (TER).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an optical CD-ROM
(Compact Disk-Read Only Memory) device, DVD (Digita
l Video Disk device, DVI (Digital Video Interactiv)
e) The present invention relates to a recorded information reproducing apparatus capable of reproducing information recorded on an optical disk such as a device.
The present invention relates to a technology capable of generating a track crossing signal with high accuracy and effective for speeding up and stabilizing data access time.

[0002]

2. Description of the Related Art In a disk information reproducing apparatus such as a CD-ROM apparatus, information optically read from a disk by a pickup is output by a preamplifier as a high frequency signal, a mirror area detection signal, a focus error signal, a tracking error signal, and the like. Is done. The high frequency signal is binarized and subjected to demodulation and error correction. The mirror area detection signal is a signal obtained by binarizing the envelope of the high-frequency signal and is a signal indicating a mirror area (a non-track portion of the disk, that is, an area between tracks), and is used for generating a track crossing signal. The focus error signal and the tracking error signal are used for each servo control of focusing and tracking of the pickup and for control of track jump.

Meanwhile, in a CD-ROM device which is one of the recent disk information reproducing devices, the rotational speed of the disk is set to 12 or less.
The reproduction speed of recorded information is improved by increasing the speed to double speed, 24 times speed, or the like. Here, the 12 and 24 times speeds are defined as the standard speed and the reproduction speed of a music CD, respectively.
This means that it is four times faster. In general, a CD-ROM device is designed to be able to reproduce both music and data disks. When a data disk is reproduced, it is desirable that the reading speed be higher in terms of speeding up access. In addition, since the playback speed of CD-ROM devices has been increasing in several months today, the playback speed must be gradually increased in advance for such extremely short playback speed conversion cycles. Consideration that can respond to hardware or software is required. However, even if the reading speed of data is increased by increasing the rotation speed of the disk, if the access operation for moving to the desired track is not performed quickly and accurately, it takes time to read out the target information, The data read time cannot be reduced.

[0004]

The present inventors have studied a technique for moving a pickup to a desired track at a high speed by a track count method. The track count method is a control in which the number of tracks traversed by the pickup is measured while moving the pickup in the radial direction of the disk, and the movement of the pickup is stopped when the number of traversed by the pickup is reached. Do not use. In the control of the track count method, the number of tracks crossed by the pickup is measured using a track crossing signal generated based on a high-frequency signal read from a CD-ROM disk. The track crossing signal is generated based on the envelope signal of the high-frequency signal read from the disk while moving the pickup in the radial direction of the disk. This envelope signal is a frequency signal having one cycle of the track pitch in the disk radial direction. In a signal used in the process of generating a track crossing signal, a carrier component of a high-frequency signal appears as a noise component. Also, when the moving speed of the pickup is increased, the level change (of the bottom value) of the high-frequency signal when traversing the track is increased (in other words, the frequency of the frequency signal is increased), and the frequency of the track traversal signal is also increased. However, if the speed of the pickup is increased, the number of information pits passing through the pickup being traversed becomes relatively small when the pickup traverses the truck.
The density of the high-frequency signal read by the pickup while traversing the track is reduced. As the density of the high-frequency signal read during track traversal becomes lower, the accuracy of the envelope signal decreases. That is, the noise component superimposed on the envelope signal increases. Furthermore, since the cross-track signal used for counting the number of crossed tracks is generated using the envelope signal, the accuracy of the cross-track signal also decreases. As a result, the number of track traverses that is determined from the number of changes in the track traverse signal has a relatively large error with respect to the actual number of traverses, and as a result, the time required for the pickup to reach the desired track is reduced. You can't do that.

Therefore, it is necessary to determine the moving speed of the pickup in consideration of how stably the track crossing signal can be output up to a high frequency.

An object of the present invention is to provide a disk information reproducing apparatus capable of generating an envelope signal of a high-frequency signal at the time of traversing a track with high accuracy even when a pickup is moved at a high speed in a disk radial direction.

Another object of the present invention is to provide a disk information reproducing apparatus capable of accurately measuring the number of track crossings by the track count method, thereby enabling high-speed data access.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0009]

The following is a brief description of an outline of a typical invention among the inventions disclosed in the present application.

That is, the disk information reproducing apparatus scans the track of the disk (1) driven by rotation with the pickup (3), and makes the pickup follow the track based on the tracking error signal (TER) obtained by the scanning. , The high-frequency signal (R
Reproduce the recorded information from F). The disc information reproducing apparatus converts a track crossing signal (TCR), which is changed in synchronization with a track crossing cycle of the pickup when the pickup is moved in a radial direction of the disc, into the high-frequency signal (RF) and the tracking error signal. (TER) and a track crossing signal generation circuit (6) for generating the signal. The track crossing signal generation circuit includes signal density multiplying means (13) for multiplying the signal density of the high frequency signal. A track crossing signal (TCR) based on an envelope signal (EVP) of a high density high frequency signal (DRF) output from the signal density multiplying means and the tracking error signal (TER).
Is generated.

More specifically, a high frequency signal (RF) is read from the disk (1) using a pickup (3) controlled by a servo circuit (10), and error signals (FER, TER) obtained from the read high frequency signal. A disk information reproducing device that generates a servo control signal based on the servo circuit and reproduces a high-frequency signal sequentially read from the disk,
Signal density multiplying means (13) for multiplying the signal density of the high frequency signal read from the pickup, and envelope detecting means (40) for generating an envelope signal (EVP) of the high density high frequency signal output from the means; ,
A track crossing signal generation circuit (6) including: mirror area detection means (41) for comparing the envelope signal output from the envelope detection means with a reference level and outputting a signal indicating a mirror area as a binarized pulse signal Having. This circuit tracks the cross-track signal (TCR), which is changed according to the cross-track period when the pickup is forcibly moved in a direction crossing the track in order to cause the pickup to jump to a desired track, with the high-density high-frequency signal. Generated based on the error signal.

When the pickup is moved at a high speed in the radial direction of the disk in order to access data on the disk at a high speed, the level change (at the bottom portion) of the high-frequency signal read from the disk becomes sharp, whereby The envelope signal of the high-frequency signal has a higher frequency. Since the track crossing signal is generated based on the envelope signal, the frequency of the track crossing signal is also increased. If the high-frequency signal density in the envelope signal at that time becomes sparse, the noise component superimposed on the waveform becomes large and coarse due to the detection time constant of the envelope detection means, and the accuracy of the envelope signal falls significantly. . In the above-described means, the signal density of the high-frequency signal is multiplied to perform envelope detection, so that a noise component superimposed on the envelope waveform is reduced and made smaller,
As a result, the envelope signal waveform can favorably follow the change (of the bottom value) of the high-frequency signal. Therefore, even when the pickup is moved at a high speed, a highly accurate envelope signal can be obtained, and a mirror area detection signal using the signal and a track crossing signal using the signal can also be obtained with high accuracy. Since the counting error of the number of traversing tracks is eliminated, the pickup can be moved to a desired track at a high speed, and high-speed data access is possible.

For example, the track crossing signal generating circuit (6) includes the signal density multiplying means (13) and a high-density high-frequency signal (DR) output from the signal density multiplying means.
F) Envelope detection means for detecting the envelope, and binarization of the envelope signal (EVP) output from the envelope detection means, so that a track portion and a non-track portion along the radial direction of the disk can be separated. A mirror area detecting means (41) for generating a pulse-shaped mirror area detection signal having a different logical value; and binarizing the tracking error signal to thereby obtain a pitch of a track central portion along a radial direction of the disk. A waveform shaping circuit (43) for generating a pulse-like timing signal having one cycle as a cycle, and latching the mirror area detection signal in synchronization with a change in the timing signal generated by the waveform shaping circuit. The track crossing signal (TCR)
And a latch means (44) for outputting the result. Even if the timing signal generated by the waveform generation circuit is partially disturbed by the influence of noise or the like, the timing signal only provides the latch timing for the latch means, and the latch data is a highly accurate envelope as described above. Since the accuracy is improved by the signal, the partial disturbance of the timing signal is limited to the partial disturbance of the cycle of the track crossing signal, and the number of changes (cycle number) of the track crossing signal is inconsistent with the number of crossing tracks. The desired increase or decrease is prevented. Therefore, since the counting error of the number of crossing tracks is eliminated, the pickup can be moved to a desired track at a high speed, and high-speed access of data becomes possible.

The signal density multiplying means includes a differential amplifier having one input terminal supplied with a reference voltage and the other input terminal supplied with the high-frequency signal (RF) via a coupling capacitor (50). Circuit (AMP), a clip circuit (CLP) for performing a clipping operation based on a predetermined voltage with respect to a differential output signal output from the differential amplifier circuit, and a differential output signal output from the clip circuit And an adder circuit (ADD) for adding. This makes it possible to generate a high-density high-frequency signal (DRF) whose signal density is doubled by adding the clipped differential high-frequency signals whose phases are shifted from each other by 180 °.

The envelope detecting means generates an envelope by performing charging and discharging in accordance with the cycle of the output signal from the signal density doubling means, and comprises an apparatus for determining a charging and discharging time constant and a constant current source. And can be configured by:

The control means for the track jump by the track count method using the track crossing signal monitors the number of track crossings based on the track crossing signal while moving the pickup in the radial direction of the disk, and performs track crossing. When it is detected that the number of times reaches the target number, the movement of the pickup in the disk radial direction is stopped, and the pickup is moved to the target track.

[0017]

FIG. 1 shows a CD-ROM reproducing apparatus as an example of a disk information reproducing apparatus according to the present invention. The CD-ROM reproducing apparatus drives the disc 1 at a constant linear velocity (Constant Liner Verocity) or at a constant angular velocity (Constant Angular Verocity) by a disc motor 2, and reads data recorded on the disc 2 by an optical pickup 3. The read data (current signal) is supplied to the high-frequency amplifier 5. Pickup 3
Is read by the high-frequency amplifier 5
The signal is converted into a high-frequency signal RF as an analog voltage signal, a focus error signal FER, and a tracking error signal TER.

The converted high-frequency signal RF is sent to the digital signal processing circuit 7. Digital signal processing circuit 7
Is, although not particularly limited, the supplied high-frequency signal RF
Data slice circuit (DSLC) 70, PLL circuit (PLL) 71, data processing circuit (DTRS) 72, and rotational speed control circuit (ROTC) 7 for disk motor 2
3 and the like are realized.

The data (EFM signal) binarized by the data slice circuit 70 is sent to the PLL circuit 71.
The PLL circuit 71 operates to generate a PLL clock synchronized with the input data. The binarized data (EFM signal) together with the PLL clock is sent to the data processing circuit 72,
The data is subjected to data processing such as FM demodulation, subcode demodulation, and error correction, and is sent to the CD-ROM decoder 8. Thus, the PLL circuit 71 generates a reproduction clock synchronized with the EFM signal for reading the EFM signal. The data sent to the CD-ROM decoder 8 is extracted in accordance with the information format of the CD-ROM disc 1 and subjected to error correction processing by ECC.
l Computer System Interface and IDE (Integrated
Device Electoronics) is converted to a data format according to the external interface specification
Supplied to the CPU.

The rotation control circuit 73 of the disk motor 2 realized by the digital signal processing circuit 7 detects a synchronizing signal from the binarized signal (EFM signal) and detects the rotation speed of the disk 1 by the disk motor 2. Control is performed so that, for example, the linear velocity of the truck with respect to the pickup 3 is kept constant.

The focus error signal FER and the tracking error signal TER output from the high frequency amplifier 5 are supplied to a servo circuit 10. The servo circuit 10 includes the pickup 3
And servo control of the pickup 3 by the thread motor 4 and track search control. The focusing servo controls the objective lens so that the relative distance between the objective lens of the pickup and the signal surface of the disk is kept constant with respect to the runout of the disk 1, and the disk signal surface is located within the focal depth of the laser beam. It is. The tracking servo is a control for accurately tracing the laser beam of the pickup 3 along a track at, for example, 1.6 μm intervals even when the disk 1 rotates eccentrically. The feed servo is a control in which the pickup 3 is moved in the radial direction of the disk by the thread motor 4 and is moved to follow a spiral track. The tracking of the pickup 3 is achieved by the tracking servo and the feed servo. In the track search control, in order to move the pickup 3 to the target track on the disk 1, the tracking servo is deactivated and the thread motor 4 is moved in the disk radial direction toward the desired track, so that the pickup 3 Is a control to operate the tracking servo again when the tracking servo is reached.

The system control circuit 11 is interfaced with the track traversing signal generation circuit 6, the digital signal processing circuit 7, the CD-ROM decoder 8, the output processing circuit 9, the servo circuit 10, and the like, and controls the entire CD-ROM reproducing apparatus. Control. The configuration can be realized by a microcomputer, a random logic circuit, or the like.

The CD-ROM reproducing apparatus of this embodiment has, although not particularly limited, an operation mode of a standard speed reproduction and a 24 × speed reproduction. For this purpose, as shown in FIG. 1, the digital signal processing circuit 7 has speed switching logic means 100 for controlling the rotation speed of the disk motor 2 and controlling the digital signal processing speed according to the operation mode. .

The servo circuit 10 shown in FIG. 1 is configured as an analog servo, but as shown in FIG. 2, the servo circuit 10 is configured as a digital servo circuit realized by the digital signal processing circuit 7. It is also possible.

FIG. 3 shows an example of the high-frequency amplifier 5. FIG. 3 typically shows six photodiodes A, B, C, D, E, and F as components of the pickup. The pickup 3 is, for example, of a three-spot type, and includes two sub-spots 30 arranged on the left and right of the track or the information pit, as schematically shown in FIG.
Photodiodes A, B, C, D, E, and F that receive light reflected from the main spot 31 and the main spot 32 are provided. FIG.
As shown in FIG. 2, 2 corresponding to the main spot 32
The respective output currents of the photodiodes A, C and B, D on the diagonal line of the set are added and converted into voltages by the current-voltage conversion circuits 20, 21. The difference between the converted voltages is detected by a subtraction circuit 25, and this is used as a focus error signal FER. When the objective lens of the pickup 3 matches the depth of focus, the main spot 32 has a circular shape for uniformly collecting light on the photodiodes A to D.
It is an elliptical shape that focuses light exclusively on C, and if too far, it is an elliptical shape that focuses light only on B and D. Therefore, the output of the subtractor 25 is set to "0" when the depth of focus is matched. The focus error signal FER has a signal waveform as shown by S1 in the figure, and the servo circuit 10 controls the position of the objective lens of the pickup 3 by a focusing actuator (not shown) so that the focus error signal FER crosses zero.

Output currents of the photodiodes E and F corresponding to the sub-spots 30 and 31 are converted into voltages by current-voltage conversion circuits 22 and 23, respectively. The difference between the converted voltages is detected by a subtraction circuit 26, which is used as a tracking error signal TER. When the objective lens of the pickup 3 is located at the center of the pit or track, the sub spots 30 and 31 to the pit or track are provided.
Of the sub-spot 31 on the left side is relatively large in the case of the rightward shift, and the opposite is true in the case of the leftward shift. Therefore, when the objective lens is completely following the information pit or track, the output of the subtractor 26 is set to "0". The tracking error signal TER has a signal waveform as shown by S2 in the figure, and the servo circuit 10 controls the position of the objective lens of the pickup 3 by a tracking actuator (not shown) so that the tracking error signal TER crosses zero.

The outputs of the current-to-voltage conversion circuits 20 and 21 are supplied to an addition and waveform equalizer 24, where a high-frequency signal RF
It is said. This high-frequency signal RF is EFM according to the present embodiment.
This is a modulation signal, and its lower envelope waveform S3 is maximum immediately above the track and minimum at the center position between adjacent tracks. The modulated signal waveform is a signal waveform including a period from 3T to 11T with respect to the reference period T.

FIG. 5 shows an example of a block diagram of the servo circuit 10 and the track crossing signal generation circuit 6.
The servo circuit 10 includes a tracking servo circuit 45 for performing the tracking servo control, a thread servo circuit 46 for performing the thread servo and the feed servo, and a focus servo circuit 4 for performing the focusing servo control.
7. The tracking servo circuit 4
5. The thread servo circuit 46 and the focus servo circuit 47 receive the servo control data from the system control circuit 11, respectively, and control the servo control signals TCTL, SCTL, FCTL based on the tracking error signal TER and the focus error signal FER.
Generate CTL, pick up 3 and thread motor 4
To supply.

When the servo circuit 10 shown in FIG. 5 is the digital servo circuit shown in FIG. 2, the servo circuit 10 is included in the digital signal processing circuit 7.

The track traversing signal generation circuit 6 is a circuit for generating a track traversing signal TCR for moving the pickup 3 to a desired track by a track counting method, and a signal for doubling the signal density of the high frequency signal RF. Density doubling circuit 13 and its output double-density high-frequency signal DRF
, An envelope detector 40 for detecting the envelope, a mirror area detector 41 for binarizing the output, a low-pass filter (LPF) 42 for the tracking error signal TER, binarizing the output and detecting the rising and falling edges. A waveform shaping circuit 43 for detecting the waveform shaping circuit 43
The latch circuit 44 latches the output of the mirror area detector 41 in accordance with the edge detection signal output from the latch circuit 44 and outputs a track crossing signal TCR.

FIG. 6 shows a track crossing signal generation circuit 6.
FIG. 7 shows a specific example of a track crossing signal generation operation by the track crossing signal generation circuit 6. In the track jump, the operation of the tracking servo circuit 45 is stopped. Thereafter, the sled motor 4 is started by the sled servo circuit 46, and the pickup 3 is moved in the radial direction of the track. As a result, a high-frequency signal RF and a tracking error signal TER as shown in FIG. 7 are output. The 0 level in the high-frequency signal RF in FIG. 7 corresponds to a so-called dark level in which the outputs of the photodiodes A to D of the main spot in FIG. 2 are 0, and the M level is a so-called mirror surface in which reflected light from the main spot is maximized. R corresponds to the (mirror) level, and R indicates an envelope (envelope) in which the pit surface level changes as the track crosses the main spot. The tracking error signal TER changes depending on the position of the sub spots 30 and 31 in FIG. 4 with respect to the track. Main spot 3 at the center of the truck
Since the outputs of the sub-spots 30 and 31 are set to be the same when the position 2 is located, the tracking error signal TER output from the subtracter 26 is set to 0, and the spot moves relatively right on the track. Subtractor 2 when moved to
The output of No. 6 is changed to the positive side when it moves to the left and to the negative side, and the waveform between tracks is reversed from the waveform immediately above the track. Here, the signal frequencies of the high frequency signal RF and the tracking error signal TER in the track jump are increased in proportion to the moving speed of the pickup 3 by the sled motor 4.

The envelope detector 40 generates an envelope signal EVP of the high-frequency signal RF by performing charging and discharging in accordance with the cycle of the output signal from the signal density doubling circuit 13, the details of which will be described later. But,
An apparatus for determining a charge / discharge time constant and a constant current source are provided. The envelope signal EVP generated by the envelope detector 40 is converted into a binary pulse signal by the level comparator 80. The high-frequency component of the tracking error signal TER is removed by a low-pass filter 42,
Is converted into a binary pulse signal to detect an edge. The position where the signal strength is highest in the high-frequency signal RF is right above the track, and in this state, the tracking error signal TER
Is at the zero crossing point. Therefore, the tracking error signal TER has a phase of about 9 with respect to the envelope signal EVP.
It is off by 0 °. The latch circuit 83 latches the mirror area detection signal, which is the binarized pulse of the envelope signal EVP, in synchronization with the edge change of the binarized pulse of the tracking error signal TER, and outputs the track crossing signal TCR as a pulse signal. The pulse change of the track crossing signal TCR is counted by the digital signal processing circuit 7, in other words, the number of tracks crossed by the pickup 3 is counted. The traversing of the pickup 3 by the thread motor 4 is continued until the counted value reaches a predetermined value.

FIG. 8 is a circuit diagram showing an example of the envelope detector 40. In this circuit, a circuit in which a capacitor 72 and a constant current source 70 are connected in parallel is connected between a power supply voltage Vcc and an emitter of a PNP transistor 71, and the PNP transistor 7
1 is connected to ground GND, the output of the emitter of the PNP transistor 71 is coupled to the base of the NPN transistor 73, and the NPN transistor 73 and the resistor 74
And an emitter follower output circuit. PNP
A high frequency signal RF is supplied to the base of the transistor 71, and a capacitor 72 connected to the emitter of the transistor 71.
Is charged and discharged via the constant current source 70 at each cycle of the high-frequency signal RF, charging is performed in response to a period in which the waveform of the high-frequency signal RF increases the difference from its peak value, and discharging is performed in the reverse period. Done. At this time, the discharge time constant, that is, the discharge time T, is expressed by T = C
-Represented as V / I. As a result, an envelope signal EVP corresponding to the lower envelope of the high-frequency signal RF is obtained at the emitter of the transistor 72. The envelope signal EVP shown in FIG. 8 is shown as a smooth waveform, but microscopically, a sawtooth noise component according to a discharge time constant is superimposed.

FIG. 9 shows such a sawtooth noise component. FIG. 7A shows a case where the signal density of the high-frequency signal RF is low, and FIG.
3 shows a case where the signal density is high. The state (a) corresponds to the case where the movement of the pickup 3 by the sled motor 4 is fast, and the state (b) corresponds to the case where the movement is slow. Since the constant of the envelope detection circuit 40 is set so that the relationship between the carrier frequency and the discharge time constant is in an optimal state, the number of noise components superimposed on the envelope signal EVP, that is, the number of detections is determined by the carrier frequency Is higher (the signal density is denser). For example, in FIG. 10A, the number of detections is small because the carrier signal density is sparse, so that the noise component is relatively large and coarse, so that an envelope waveform with high accuracy cannot be created. Therefore, even when the movement of the pickup 3 by the thread motor 4 is accelerated, the number of detections is increased and the noise component becomes relatively small and fine by increasing the carrier signal density as shown in FIG. ,
As a result, a highly accurate envelope waveform can be obtained. As a result, the frequency of the track crossing signal TCR can be stabilized to a high frequency, so that a good track crossing signal TCR can be obtained even when the pickup is moved to a desired track at a high speed when accessing data. In addition, the high-speed movement of the pickup 3 that can support high-speed reproduction can be performed even in the track count access method.

FIG. 10 shows a specific example of the signal density doubling circuit 13 for doubling the signal density of the high frequency signal RF. This circuit includes a capacitor 50 for AC-coupling a high-frequency signal RF input from IN, and resistors 51, 52, 54, 56,
58, 59, NPN transistors 53, 57, constant current source 5
5 and a differential amplifier circuit AMP composed of a constant voltage source 60, a clip circuit CLP composed of resistors 62 and 64, PNP transistors 63 and 65 and a constant voltage source 61, and an adder circuit ADD having resistors 66 and 67. You.

FIG. 11 shows an operation waveform diagram of the signal density doubling circuit 13. The high-frequency signal RF as an analog signal output from the high-frequency amplifier 5 is supplied from the IN state to the capacitor 50 and AC-coupled to the A state. The function of the differential amplifier circuit is that the NPN transistors 53, 5
7 is applied to the signal input to the base of transistor 5.
7, a signal having the same phase as the difference component of the input signal is amplified and output, and a signal having a phase opposite to the difference component of the input signal is amplified and output from the collector of the transistor 53. Is what is done. Therefore, when the waveform of A is supplied to the differential amplifier circuit AMP, the difference from the constant voltage source (reference voltage) 60 is amplified, and the collector of the transistor 57 which is a non-inverted output has a waveform B in phase with the waveform of A. But,
A waveform C whose phase is shifted by 180 ° from the waveform of A is output to the collector of the transistor 53 which is an inverted output.
At this time, the waveforms indicated by B and C have an opposite phase relationship.

Further, the respective outputs B and C are supplied to separate clip circuits. The clip circuit functions to remove (clip) a signal input to the bases of the PNP transistors 63 and 65 from a voltage higher than the voltage of the constant voltage source 61 and output the signal from the emitters of the PNP transistors 63 and 65. Therefore, the output B from the differential amplifier circuit,
C is clipped by the clipping circuit CLP at a voltage higher than the reference voltage, and is output in the D and E waveform states. In this state, a signal lower than the reference voltage 61 appears in D and E alternately. By adding the D and E signals by the adder circuit ADD, an output signal whose signal density is doubled with respect to the IN state of the input signal is obtained in the OUT state.

The signal density doubling circuit 1 configured as described above
According to 3, even when the pickup 3 is moved by the sled motor 4 at high speed and the signal density of the high frequency signal RF becomes low, the signal density doubling circuit 13 reduces the signal density of the high frequency signal RF to about In order to double the frequency, the envelope detection circuit 40 that inputs the double-density high-frequency signal DRF having the increased signal density requires the number of times of charge / discharge operation for envelope detection (charge / discharge operation for each cycle of the double-density high-frequency signal). It is possible to obtain an envelope waveform that is increased and has a small (fine) noise component and high accuracy. Therefore,
A track crossing signal TCR in which the number of changes does not undesirably increase or decrease can be generated.

Here, the process of generating the track crossing signal TCR will be described in more detail with reference to FIG. It is apparent from the above description that the envelope signal EVP can be generated with high accuracy by using the double-density high-frequency signal DRF. Track crossing signal TCR is envelope signal EVP
Is not the binary signal itself. This is because it is not possible to know the timing at which the pickup has passed the center of the truck from this signal. The track crossing signal TCR is an edge detection signal E which is a binary output of the tracking error signal TER.
This is an output signal of the latch circuit 83 using DG as a latch clock. The data input of the latch circuit 83 is a binarized output of the envelope signal EVP. At this time, the tracking error signal TER itself is a relatively noisy signal.
The digitized output EDG does not have the complete rectangular pulse waveform shown in FIG. There is a possibility that an extra edge is mixed near the original edge. Even if extra edges are mixed,
Since the pulse waveform of the binarized output of the envelope signal EVP is highly accurate, even if an extra edge exists in the edge detection signal EDG, the period of the track crossing signal TCR is only partially changed, and The number of changes in the crossing signal TCR does not undesirably increase or decrease.

The control for the track jump by the track count method using the track crossing signal TCR is based on the number of changes (cycle number) of the track crossing signal TCR while moving the pickup 3 in the radial direction of the disk 1. The number of track traverses is monitored to detect the number of track traverses reaching the target number, and the movement of the pickup 3 in the disk radial direction is stopped, and the pickup is moved to the target track. Such operation is performed by the digital signal processing circuit 7 and the system control circuit 1.
1 is performed.

Therefore, according to the above-described CD-ROM reproducing apparatus, the pickup can be moved to an accurate position with almost no error even if the moving speed of the pickup is increased in the track jump of the track count method. High-speed access becomes possible.

Although the invention made by the present inventor has been specifically described based on the embodiments, it is needless to say that the present invention is not limited to the embodiments and can be variously modified without departing from the gist thereof. No.

For example, the speed N times the standard reproduction speed is not limited to 24 times, and can be changed as appropriate. Further, the circuit configuration of the envelope detection circuit, the mirror area detection circuit, the waveform shaping circuit, and the configuration of the signal density doubling circuit are not limited to the above-described embodiment, and can be changed as appropriate. The high density of the high frequency signal is not limited to the double density, but may be approximately four times, eight times, or the like. FIG.
What is necessary is just to arrange a plurality of circuits of 0 in series.

In the above description, the invention made mainly by the present inventor has been used in the background of the CD-ROM
The case where the present invention is applied to a reproducing apparatus has been described, but the present invention is not limited to this. The present invention is applied to CD-ROM, DV
D and DVI recording information playback devices as well as write-once CDs, rewritable CDs, DVDs, PDs (phase change optical disks), MDs (Min
It can be widely used for a device for reproducing recorded information from a magneto-optical disk such as an i Disk) and an MO (Magnet Optical Disk).

[0045]

The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows.

That is, according to the present invention, even when an access is performed by moving the pickup at a high speed, the envelope signal can be generated with high accuracy by increasing the signal density of the high-frequency signal when traversing the track. By generating a track crossing signal using the envelope signal, the number of tracks crossed by the pickup can be accurately measured, and the speed of data access by the sensorless track count method can be increased.

[Brief description of the drawings]

FIG. 1 is a block diagram of a CD-ROM playback device that is an example of a disc information playback device according to the present invention.

FIG. 2 is a CD-R in which the analog servo circuit of FIG. 1 is configured as a digital servo circuit by a digital signal processing circuit.
It is a block diagram of an OM playback device.

FIG. 3 is a circuit diagram illustrating an example of a high-frequency amplifier.

FIG. 4 is an explanatory diagram showing an example of an arrangement of photodiodes of a three-spot type pickup.

FIG. 5 is a block diagram illustrating an example of a servo control circuit and a track crossing signal generation circuit;

FIG. 6 is a circuit diagram illustrating an example of a track crossing signal generation circuit.

FIG. 7 is a waveform chart for explaining a process of generating a track crossing signal.

FIG. 8 is an example circuit diagram of an envelope detection circuit.

FIG. 9 is an explanatory diagram showing a relationship between an envelope signal of a high-frequency signal and the number of times of detection.

FIG. 10 is an example circuit diagram of a signal density doubling circuit.

FIG. 11 is a waveform chart for explaining a generation process of a double-density high-frequency signal.

[Explanation of symbols]

 Reference Signs List 1 disc 3 pickup 5 high frequency amplifier 6 track traversing signal generation circuit 7 digital signal processing circuit 10 servo circuit 13 signal density doubling circuit 40 envelope detector 41 mirror area detection circuit 44 latch circuit 45 tracking servo circuit 46 thread servo circuit RF high frequency signal DRF Double density high frequency signal TER Tracking error signal TCR Track crossing signal

Claims (4)

[Claims] 1. A disk information for scanning a track of a rotating disk by a pickup, causing the pickup to follow the track based on a tracking error signal obtained by the scanning, and reproducing recorded information from a high-frequency signal obtained by the scanning. A reproducing apparatus for generating, by inputting the high-frequency signal and the tracking error signal, a track crossing signal that is changed in synchronization with a track crossing cycle of the pickup when the pickup is moved in a radial direction of a disk; A track crossing signal generation circuit, wherein the track crossing signal generation circuit has signal density multiplying means for multiplying the signal density of the high-frequency signal, and generates a high-density high-frequency signal output from the signal density multiplying means. Track based on the envelope signal and the tracking error signal Disc information reproducing apparatus, characterized in that for generating a disconnection signal. 2. The signal processing circuit according to claim 1, wherein the track crossing signal generation circuit includes a signal density multiplier, an envelope detector for detecting an envelope of a high-density high-frequency signal output from the signal density multiplier, and an envelope detector. Mirror area detection for generating a pulse-shaped mirror area detection signal in which a logical value differs between a track portion and a non-track portion along the radial direction of the disk by binarizing the output envelope signal. Means, a waveform shaping circuit for generating a pulse-like timing signal having a pitch of a track center portion along the radial direction of the disk as one cycle by binarizing the tracking error signal; and the waveform shaping circuit. Latching the mirror area detection signal in synchronization with a change in the generated timing signal,
2. The disc information reproducing apparatus according to claim 1, further comprising: latch means for outputting the latched signal as the track crossing signal. 3. The signal density multiplying means includes: a differential amplifier circuit having one input terminal supplied with a reference voltage and the other input terminal supplied with the high-frequency signal via a coupling capacitor; A clip circuit that performs a clip operation based on a predetermined voltage with respect to a differential output signal output from the differential amplifier circuit, and an addition circuit that adds a differential high-frequency signal output from the clip circuit, 3. The disc information reproducing apparatus according to claim 1, wherein the adding circuit outputs a high-density high-frequency signal in which the density of the high-frequency signal is approximately doubled. 4. A method of monitoring the number of track traversals based on the track traversing signal while moving the pickup in the radial direction of the disk. 4. The disc information reproducing apparatus according to claim 1, further comprising control means for stopping the movement of the pickup and moving the pickup to a target track.