JPH0757383A - Spindle servo circuit - Google Patents

Abstract

PURPOSE:To ensure excellent playability at the ordinary time and to stabilize spindle servo when vibration occurs. CONSTITUTION:At the ordinary time when a shock detecting circuit 15 does not detect the shock, a control circuit 16 narrows a protection period in a synchronization protecting circuit 100, the detecting signal for synchronizing signal erroneously detected by a detecting circuit 9 for synchronizing signal due to flaws, stains, etc., is prevented from being inputted to a CLV control circuit 11 and good playability is ensured. On the other hand, when the shock detecting circuit 15 detects a shock, the control circuit 16 widens the protection period in a synchronization protecting circuit 100, makes the detecting signal for synchronized signal, which is correctly detected by the detecting circuit 9 for synchronizing signal but its timing is largely shifted due to the influence of jitter, surely input to the CLV control circuit 11 and the spindle servo is kept in a stable state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle servo circuit, and more particularly to a spindle servo circuit for controlling the rotation of a disc at a constant linear velocity using a synchronizing signal recorded on the disc such as a CD player and a mini disc system.

[0002]

2. Description of the Related Art In a CD player, music data cannot be demodulated unless a compact disc (CD) is rotated at a prescribed constant linear velocity. For this reason, the spindle motor that rotates the compact disc is controlled to rotate at a constant linear velocity by the spindle servo circuit. A frame synchronization signal recorded at a constant interval on the compact disc is used for this rotation control, and a spindle servo is applied so that the frame synchronization signal detected from the compact disc has a constant time interval.

FIG. 3 shows the structure of a reproducing system of a CD player including a conventional spindle servo circuit. 1 is a compact disc, 2 is a turntable on which the compact disc is mounted, 3 is a spindle motor for rotating the compact disc, 4 is an optical pickup for detecting a recording signal of the compact disc, and 5 is a thread motor for sending the optical pickup in the disc radial direction. Reference numeral 6 denotes an RF amplifier that creates an EFM signal, a focus servo signal FE, a tracking servo signal TE, etc. from the output of the optical pickup, and 7 indicates focus servo and tracking servo for the optical pickup based on the focus servo signal FE and the tracking servo signal TE. A pickup servo circuit 8 for applying a sled feed servo to a sled motor, a reference clock 8 is extracted from an EFM signal by a PLL circuit (not shown), and based on the extracted reference clock. A bit data reading circuit for reading a bit data string, a sync signal detecting circuit 9 for detecting a frame sync signal from the bit data string, and a sync signal detecting circuit 10 for predetermined protection before and after sandwiching a timing of a sync signal to be detected next. A synchronization protection circuit that allows the synchronization signal detection signal that is the output of the synchronization signal detection circuit to pass only during the period, and 11 is a CLV control circuit. Among these, 11a generates a voltage that is inversely proportional to the frequency of the synchronization signal detection signal. A frequency-voltage converter (f-V), 11b is a phase comparator that compares the phase of a reference signal of a predetermined specified frequency (7.35kHz) and a sync signal detection signal, and outputs a phase difference signal, and 11c is a phase comparator. Is an LPF for integrating the output of the above, and 11d is an adder for adding the output of the frequency-voltage converter and the output of the LPF. 12 is CLV
The motor driver drives the spindle motor 3 based on the output of the control circuit 11. The output voltage from the CLV control circuit 11 rises when the frequency of the sync signal detection signal is low with respect to the predetermined specified frequency, and conversely drops when the frequency of the sync signal detection signal is high with respect to the predetermined specified frequency. Therefore, in the motor driver 12, the frequency of the sync signal detection signal is
The spindle motor 3 is rotated so that 7.35kHz is maintained.

Reference numeral 13 is an EFM demodulation circuit for extracting audio symbol data and subcode data from a bit data string by using a sync signal detection signal, a reference clock and the like, and 14 is an unscramble, deinterleave or CICR code for music symbol data. It is a CICR decoding circuit for detecting and correcting errors and extracting audio sample data. The audio sample data is D / A converted for each channel to become an analog audio signal.

Here, even if the sync signal detection circuit 9 detects an incorrect sync signal detection signal due to scratches or dirt on the compact disc, the sync protection circuit 10 outputs the false sync signal detection signal to the CLV control circuit 11 or the like. 10a is a window signal generation circuit for generating a window signal that is at a high level for a predetermined fixed period, and 10b is a logic of the synchronization signal detection signal and the window signal input from the synchronization signal detection circuit 9. It is an AND circuit that takes the product.

FIG. 4 is an explanatory diagram for explaining the operation of the synchronization protection circuit 10. The subcode, audio symbol data, and parity are recorded on the compact disc 1 in a frame unit format as shown in the upper part of FIG.
A 24-bit frame synchronization signal is arranged at the beginning of each frame. The synchronization signal detection circuit 9 inputs the bit data string to a shift register having a length of 24 bits according to the clock input from the PLL circuit of the bit data reading circuit 8, and the frame synchronization signal having a predetermined bit pattern is stored in the shift register. Then, the synchronizing signal detection signal is output.

On the other hand, the window signal generating circuit 10a receives a channel clock input from the outside (the cycle T is 1 / 4.3218MH).
In accordance with z), the sync signal detection signal that has been normally output to the subsequent stage becomes high level for ± 6 channel clocks around the timing at which the sync signal detection circuit 9 should detect the frame sync signal next. During this period, a window signal that is low level is generated. Therefore, only when the sync signal detection circuit 9 detects a normal frame sync signal in consideration of jitter (see A _{1 to} A _{3 in} FIG. 4), the sync signal detection signal is output from the sync protection circuit 10. When a frame sync signal is detected in a period other than the window period (see E in FIG. 4), bit inversion occurs in audio symbol data, parity, etc. due to scratches, dirt, etc., resulting in incorrect detection. The output of the incorrect sync signal detection signal is blocked, and the disturbance of the spindle servo and the accompanying demodulation error of the EFM demodulation circuit 13 are avoided.

Here, the window period is narrow within ± 6 channel clocks around the timing at which the frame sync signal should be detected, because the strong sync protection is applied, so that a wrong sync signal due to scratches or dirt is generated. The detection signal is C
This is to prevent noise noise due to data demodulation error from being input to the LV control circuit 11 or the EFM demodulation circuit 13 and disturbing the spindle servo, and to ensure good playability.

[0009]

By the way, a car-mounted CD
In the case of a player, mechanical parts such as the turntable 2, the spindle motor 3, the optical pickup 4, and the sled motor 5 are mounted on the set chassis via a damper so that the vibration of the vehicle is not directly transmitted to the mechanical part. . In this case, the mechanical section does not stop vibrating at all, but the vibration is moderated. Moreover, due to the relationship between the support point of the damper and the position of the center of gravity of the entire mechanical section, rotational vibration occurs in the mechanical section, and the compact disc 1 may be subjected to a disturbance in the rotation direction. Then, the jitter of the bit data string output from the bit data reading circuit 8 becomes large, and even though the sync signal detection circuit 9 correctly detects the frame sync signal, it goes out of the window period and the sync protection circuit. The output may be blocked by 10. When the correct sync signal detection signal is not input from the sync protection circuit 10, the spindle servo may be greatly disturbed, or, in the worst case, the spindle servo may be disengaged despite the normal operation of the tracking servo. There was a problem that a loud noise was generated.

Some synchronization protection circuits are designed to interpolate the synchronization signal detection signal at a timing predicted in advance when the synchronization signal detection circuit does not detect the frame synchronization signal within the window period. However, in this case as well, when a disturbance in the rotational direction is applied to the compact disc 1, the interpolated timing will largely deviate from the correct timing. I will wake you up.

From the above, it is an object of the present invention to provide a spindle servo circuit which can secure good playability during normal operation and stabilize the spindle servo during vibration.

[0012]

SUMMARY OF THE INVENTION In the present invention, the above-mentioned problem is sandwiched between a sync signal detecting circuit for detecting a sync signal recorded on a disc and a timing of a sync signal to be detected next by the sync signal detecting circuit. CLV control that performs constant linear velocity control for the spindle motor based on the sync protection circuit that passes the sync signal detection output of the sync signal detection circuit and the sync signal detection signal that has passed through the sync protection circuit only during the predetermined protection period before and after In a spindle servo circuit that has a circuit, the synchronization protection circuit allows the protection period to be variable, and the shock detection circuit that detects a shock and the protection period in the synchronization protection circuit when the shock detection circuit detects a shock. If the shock is not detected by the shock detection circuit, the protection period in the sync protection circuit will be increased. It is achieved by providing a Kusuru control circuit.

[0013]

According to the present invention, during the normal time when no shock is detected, the protection period in the sync protection circuit is shortened to prevent damage
A wrong sync signal detection signal due to dirt or the like is prevented from being input to the CLV control circuit, and a protection period is widened when a shock is detected so that the correct sync signal detection signal is surely input to the CLV control circuit. . This prevents the spindle servo from being disturbed by an incorrect sync signal detection signal during normal operation and ensures good playability, while minimizing the disturbance of the spindle servo based on the correct sync signal detection signal during vibration. By doing so, it is possible to achieve stabilization and avoid the worst case of servo misalignment.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing a reproducing system of a vehicle-mounted CD player according to an embodiment of the present invention. 1 is a compact disc, 2 is a turntable on which the compact disc is mounted, 3 is a spindle motor for rotating the compact disc, 4 is an optical pickup for detecting a recording signal of the compact disc, and 5 is a thread motor for sending the optical pickup in the disc radial direction. Reference numeral 6 denotes an RF amplifier that creates an EFM signal, a focus servo signal FE, a tracking servo signal TE, etc. from the output of the optical pickup, and 7 indicates focus servo and tracking servo for the optical pickup based on the focus servo signal FE and the tracking servo signal TE. A pickup servo circuit 8 for applying a sled feed servo to a sled motor, a reference clock 8 is extracted from an EFM signal by a PLL circuit (not shown), and based on the extracted reference clock. A bit data reading circuit for reading a bit data string, 9 a sync signal detecting circuit for detecting a frame sync signal from the bit data string, 100 a sync signal detecting circuit for predetermined protection before and after sandwiching a timing of a sync signal to be detected next. It is a synchronization protection circuit that allows the synchronization signal detection signal that is the output of the synchronization signal detection circuit to pass only during the period, and the protection period can be narrowed or widened according to the control of the control circuit described later. There is.

Reference numeral 11 is a CLV control circuit, of which 1 is
1a is a frequency-voltage converter (f-V) that generates a voltage inversely proportional to the frequency of the sync signal detection signal, 11b is a reference signal of a predetermined specified frequency (7.35 kHz) and the phase comparison of the sync signal detection signal, Phase comparator that outputs a phase difference signal, 1
Reference numeral 1c is an LPF that integrates the output of the phase comparator, and 11d is an adder that adds the output of the frequency-voltage converter and the output of the LPF. A motor driver 12 drives the spindle motor 3 based on the output of the CLV control circuit 11.
The output voltage from the CLV control circuit 11 rises when the frequency of the sync signal detection signal is low with respect to a predetermined specified frequency, and conversely drops when the frequency of the sync signal detection signal is high with respect to the predetermined specified frequency. Therefore, the motor driver 12 rotates the spindle motor 3 so that the frequency of the sync signal detection signal is maintained at 7.35 kHz.

Reference numeral 13 is an EFM demodulation circuit for extracting audio symbol data and subcode data from a bit data string by using a sync signal detection signal, a reference clock and the like, and 14 is an unscramble, deinterleave or CICR code for music symbol data. It is a CICR decoding circuit for detecting and correcting errors and extracting audio sample data. The audio sample data is D / A converted for each channel to become an analog audio signal.

Reference numeral 15 compares the tracking error signal TE input from the RF amplifier 6 with a predetermined reference level to detect the presence or absence of a shock, and a shock detection signal which becomes a high level during the shock is generated. A shock detection circuit for output, 16 is a control circuit for performing window period switching control for the synchronization protection circuit 100 based on the output of the shock detection circuit 15. When the shock detection signal is not input in the normal reproduction state, the switching control signal is output. Is set to a low level, the window period is narrowed, a shock occurs, and when a high-level shock detection signal is input, the switching control signal is set to the high level for a predetermined fixed period τ to widen the window period.

In the synchronization protection circuit 100, even if the synchronization signal detection circuit 9 detects an incorrect synchronization signal detection signal due to scratches or dirt on the compact disc 1, the incorrect synchronization signal detection signal is sent to the CLV control circuit 11 or the like. This is for preventing the output, and FIG. 2 shows a specific configuration. 10
Reference numeral 0a denotes a window signal generation circuit that generates a window signal that is at a high level for a predetermined fixed period.
According to the switching control of No. 6, the window period is varied (narrow when the switching control signal is low level, wide when the switching control signal is high level). Reference numeral 100b is a logical product A of the sync signal detection signal input from the sync signal detection circuit 9 and the window signal A
It is an ND circuit. In the case of an on-vehicle CD player, the mechanical unit including the turntable 2, the spindle motor 3, the optical pickup 4, the thread motor 5 and the like is mounted on the chassis of the set via a damper, so that the vibration of the vehicle is directly affected by the mechanical mechanism. It is designed so as not to be transmitted to the department.

FIG. 2 is an explanatory diagram of the protection period switching control operation of the control circuit 16, which will be described below with reference to FIG. The subcode, audio symbol data, and parity are recorded on the compact disc 1 in a frame unit format, and a 24-bit frame synchronization signal is arranged at the beginning of each frame (see FIG. 4). The synchronization signal detection circuit 9 outputs the bit data string according to the clock input from the PLL circuit of the bit data reading circuit 8.
The signal is input to a shift register having a length of 4 bits, and when a frame synchronization signal having a predetermined bit pattern is stored in the shift register, a synchronization signal detection signal is output.

First, the operation when no shock occurs will be described with reference to the left half of FIG. When the shock is not generated and the high-level shock detection signal is not input from the shock detection circuit 15, the control circuit 1
6 determines that the normal reproduction state is set, and the synchronization protection circuit 100
The low-level switching control signal is output to the window signal generation circuit 100a of FIG. The window signal generation circuit 100a narrows the protection period when the low level switching control signal is input from the control circuit 16, and according to the channel clock (cycle T is 1 / 4.3218 MHz) input from the outside, the window signal generation circuit 100a is set to the previous stage. From the normally output sync signal detection signal to the high level during, for example, ± 6 channel clocks around the timing at which the sync signal detection circuit 9 should detect the frame sync signal, and the low level during other periods. Generate a window signal. Therefore, only when the sync signal detection circuit 9 detects a correct frame sync signal in consideration of the jitter, the sync protection circuit 100 outputs the sync signal detection signal, and the frame sync signal is detected in a period other than the window period. In case of incorrect detection as a result of bit inversion in audio symbol data or parity due to scratches or dirt, the output of the incorrect sync signal detection signal is blocked and the spindle servo is disturbed. The demodulation error of the EFM demodulation circuit 13 due to

Here, since the window period is narrowed by ± 6 channel clocks around the timing at which the frame sync signal should be detected, strong sync protection is provided and an incorrect sync signal due to scratches or dirt is produced. It is possible to prevent the detection signal from being input to the CLV control circuit 11, the EFM demodulation circuit 13 and the like and disturb the spindle servo to generate a noise sound due to a data demodulation error, and to secure good playability. When no shock occurs, the vibration in the rotating direction is not applied to the compact disc 1 and the jitter of the bit data string is small,
Even if the window period is narrowed, the correctly detected sync signal detection signal does not deviate from the window period.

In contrast to this, when the vibration of the vehicle is transmitted to the mechanical portion via the damper, a disturbance that vibrates the compact disc 1 in the rotational direction may be added depending on the positional relationship between the support point of the damper and the center of gravity of the mechanical portion. There is. The operation in this case will be described with reference to the right half of FIG. When a shock occurs, the shock detection circuit 15 detects it and outputs a high level shock detection signal to the control circuit 16. When a high level shock detection signal is input, the control circuit 16 outputs a high level switching control signal for a fixed period τ. The window signal generation circuit 100a is
When a high level switching control signal is being input from the control circuit 16, the protection period is widened and the synchronization signal that has been normally output to the subsequent stage according to the channel clock (cycle T is 1 / 4.3218MHz) input from the outside. From the detection signal, a window signal is generated that is at a high level for, for example, ± 26 channel clocks centering on the timing at which the frame synchronization signal is to be detected next by the synchronization signal detection circuit 9, and is at a low level during other periods.

Therefore, even if a large jitter occurs in the bit data output from the bit data reading circuit 8 due to the shock, and the timing at which the synchronization signal detection circuit 9 detects the regular frame synchronization signal deviates greatly from the previous time, The normal sync signal detection signal can be input to the CLV control circuit 11, the disturbance of the spindle servo can be suppressed and a stable servo state can be maintained, and the worst situation of servo deviation occurs before it happens. Can be prevented. Therefore, it is possible to improve the vibration resistance of the vehicle-mounted set and make it difficult for noise noise to occur.

If the shock detection signal has already dropped to the low level when the control circuit 16 outputs the high level switching control signal for a certain period of time τ, the control circuit 16 sets the switching control signal to the low level. Back to
If the shock is still continuing and the shock detection signal remains high level after shortening the protection period, the switching control signal is further extended by a certain period τ and held at the high level, and the protection period continues to be widened. .

According to this embodiment, during a normal time when no shock is detected, the protection period in the sync protection circuit 100 is shortened, and an incorrect sync signal detection signal due to scratches, dirt, etc. is input to the CLV control circuit 11. In order to ensure that the correct sync signal detection signal is input to the CLV control circuit 11 when the shock is detected, the spindle servo can be normally operated by the wrong sync signal detection signal. While preventing disturbance and ensuring good playability, during vibration, the spindle servo is minimized from being disturbed based on the correct sync signal detection signal to stabilize, and the worst case of servo misalignment occurs. This can be avoided, and the vibration resistance of the on-vehicle set can be greatly improved.

In the above-mentioned embodiment, the case where the sync protection circuit does not interpolate the sync signal detection signal even if the normal frame sync signal is not detected is taken as an example, but the present invention is not limited to this. Without being limited thereto, the synchronization protection circuit interpolates the synchronization signal detection signal at the timing predicted in advance when the frame synchronization signal is not detected by the synchronization signal detection circuit within the window period. However, the same can be applied. In addition, when a shock is detected, the control circuit is designed to extend the protection period for a certain period τ.However, the protection period is widened only while the shock is detected and the shock detection signal is high level. You may allow it. Further, although the spindle servo circuit of the CD player has been taken as an example, the present invention can be applied to the spindle servo circuit of other disc devices such as a mini disc system and an LD player.

[0027]

As described above, according to the present invention, the synchronization protection circuit is
The protection period can be changed, and when the shock is detected by the shock detection circuit and the shock detection circuit, the protection period in the synchronous protection circuit is widened and the shock detection circuit does not detect the shock. At this time, a control circuit for narrowing the protection period in the synchronization protection circuit is provided, and in the normal time when a shock is not detected,
The protection period in the sync protection circuit is shortened to prevent an incorrect sync signal detection signal from being input to the CLV control circuit due to scratches, dirt, etc. Since it is configured so as to be surely inputted to the CLV control circuit, the spindle servo is prevented from being disturbed by an incorrect sync signal detection signal during normal operation to ensure good playability, while a correct sync signal detection signal is applied during vibration. Based on the above, it is possible to minimize the disturbance of the spindle servo and to stabilize it, and to avoid the worst situation of servo misalignment.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a reproduction system of a vehicle-mounted CD player according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a protection period switching control operation by a control circuit in FIG.

FIG. 3 is a configuration diagram showing a reproduction system of a conventional CD player.

FIG. 4 is an operation explanatory diagram of the synchronization protection circuit in FIG.

[Explanation of symbols]

 1 Compact Disc 3 Spindle Motor 4 Optical Pickup 5 RF Amplifier 9 Sync Signal Detection Circuit 100 Sync Protection Circuit 11 CLV Control Circuit 15 Shock Detection Circuit 16 Control Circuit

Claims (1)

[Claims] 1. A sync signal detection circuit for detecting a sync signal recorded on a disk, and a sync signal detection only during a predetermined protection period before and after sandwiching a timing of a sync signal to be detected next by the sync signal detection circuit. A synchronization protection circuit for passing a sync signal detection output of the circuit, and a spindle servo circuit having a CLV control circuit for performing constant linear velocity control for a spindle motor based on the sync signal detection signal passed through the synchronization protection circuit, Makes the protection period variable, and when the shock is detected by the shock detection circuit and the shock detection circuit, the protection period in the sync protection circuit is widened and the shock detection circuit detects the shock. Control circuit that shortens the protection period in the synchronization protection circuit when not in use. The spindle servo circuit to.