JPH07114770A - Disk player - Google Patents

Abstract

PURPOSE:To obtain a disk player capable of securing the continuity of a reproducing data with a low power consumption when a track jump is generated. CONSTITUTION:The frequency of the oscillation output of a VCO28 is controlled in accordance with a servo error signal from a sindle servo signal processing circuit 18 and also the oscillation output is supplied as the system clock of a DSP circuit 10. Besides, a phase difference between the frequency division output of the oscillation output by an 1/M frequency divider 31 and the frequency division output of a reference clock by an 1/N frequency divider 33 is detected by a phase comparator 32 and the rotational speed of a disk 1 is controlled in accordance with the phase difference. Further, the reproducing speed is made possible to be set arbitrarily by selecting respective frequency division ratios of the 1/M frequency divider 31 and the 1/N frequency divider 33 and when the track jump is generated due to the disturbance of vibration, etc., at the time of a normal speed reproducing, the reproducing mode is, for instance, changed over to a double reproducing speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a digital disc called a CD (compact disc) or an MD (mini disc).
The present invention relates to a disc player for reproducing an information recording disc (hereinafter, simply referred to as a disc) such as an audio disc, in particular, a configuration in which read data from the disc is temporarily stored in a large-capacity memory and then read out from the large-capacity memory and output. Disc player

[0002]

2. Description of the Related Art In a disc player such as a CD player, when a so-called track jump occurs due to a disturbance such as a vibration during reproduction, continuity of reproduced data is ensured and sound skipping occurs. There are seismic resistant disc players that are configured not to. Here, the track jump means that an information reading light spot of a pickup that reads recording information while following a recording track (pit row) of a disc jumps over the recording track.

By the way, in a normal CD player, a data rate for reproducing from a disc (hereinafter referred to as a reproduction data rate) and a data rate for outputting audio (hereinafter referred to as an output data rate) are the same. On the other hand, in the conventional seismic CD player, by playing back the disc at a rotation speed twice as high as that of the normal CD player, the reproduction data rate higher than that of the normal CD player is obtained. The data is read at a rate and the read data is temporarily stored in a large-capacity memory, while the data is read from the large-capacity memory at an output data rate of a normal CD player and derived as an audio output.

When a track jump occurs during reproduction, the information reading light spot of the pickup is returned to the position immediately before the occurrence of the track jump, reproduction is restarted from that position, and the data stored in the large capacity memory is saved. The reproduced audio data obtained immediately after the reproduction is restarted is linked to the reproduced audio data immediately before the occurrence of the track jump, thereby ensuring the continuity of the reproduced audio data and preventing the sound skip. In addition, the disk is constantly driven to rotate at twice the rotation speed of a normal CD player, and while monitoring the amount of data stored in the large-capacity memory in the double-speed reproduction state, the data amount has a set amount. When it exceeds, it is judged that it is an overflow, and for example, the reverse jump of one track is repeated to wait.

[0005]

As described above, in the conventional seismic resistant CD player having the above-described structure, the disk is constantly driven to rotate at a high speed, so that the power consumption becomes large. For example, a portable CD player. However, it is disadvantageous when low power consumption is required. Therefore, it is an object of the present invention to provide a disc player capable of ensuring the continuity of reproduced data when a track jump occurs with low power consumption.

[0006]

According to a first aspect of the present invention, a disc player processes a reproduction signal from a disc, detects a speed difference of a rotation speed of the disk with respect to a target rotation speed, and detects a speed corresponding to the speed difference. A signal processing means for outputting a control signal, an oscillating means for supplying an oscillating output as a system clock to the signal processing means, and a frequency of the oscillating output changing in accordance with the speed control signal, and a reference clock for the oscillating output. It is configured to include a speed control unit that detects a phase difference and controls the rotation speed of the disk according to the phase difference.

According to a second aspect of the present invention, there is provided the disc player according to the first aspect, wherein the speed control means divides the oscillation output by a variable division ratio, and the reference frequency dividing means. It is configured to have a second frequency dividing means for dividing the clock with a variable frequency dividing ratio, and a phase detecting means for detecting a phase difference between respective frequency division outputs of these frequency dividing means. A disc player according to a third aspect is the disc player according to the first or second aspect, further comprising a selection unit that selects one of the oscillation output and the reference clock and supplies the selected one as a system clock to the signal processing unit. Has become.

[0008]

In the disc player according to the present invention, the frequency of the oscillation output of the oscillation means is controlled in accordance with the speed control signal of the disc, while the oscillation output is supplied to the signal processing means as a system clock. Then, by controlling the rotational speed of the disk in accordance with the phase difference of the oscillation output with respect to the reference clock, the system clock changes so that the speed control signal becomes zero.

As a result, when the reproduction mode is switched between, for example, 1 × speed reproduction and 2 × speed reproduction, the spindle servo system can be locked even during the transition of the rotation speed, and therefore information can be read from the disk even during this period. . Therefore, in the seismic resistant disc player, only when a track jump occurs due to a disturbance such as a vibration, the reproduction mode is set to the double speed reproduction to quickly charge the data in the large-capacity memory. By doing so, the power consumption of the player can be significantly reduced.

In the disc player according to the second aspect, the oscillation output of the oscillation means and the reference clock are each divided by a variable division ratio, and the rotation speed of the disc is controlled according to the phase difference of each divided output. By appropriately selecting each division ratio, the reproduction mode can be arbitrarily set such as 1 × speed reproduction and 2 × speed reproduction. In the disc player according to claim 3, when the rotational speed of the disc is roughly controlled, the oscillation output of the oscillating means is selected, and when the rotational speed reaches the target rotational speed and becomes stable, the reference clock is selected, whereby D
Since the signal can be synchronized with the A / A converter,
You can derive flutter-free audio output.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram of a control system showing an embodiment of the present invention applied to a seismic resistant CD player, for example. In FIG. 1, a disc (CD) 1 is rotationally driven by a spindle motor 2, and its recorded information is read by an optical pickup (hereinafter, simply referred to as a pickup) 3.

The pickup 3 includes a laser diode 4,
An objective lens 5 for focusing a laser light beam emitted from the laser diode 4 on the signal surface of the disc 1 as an information reading light spot, a polarization beam splitter 6 for changing the traveling direction of the reflected light beam from the disc 1, and the reflected light It is composed of a photodetector 7 for receiving a beam and the like, and is provided so as to be movable in the disk radial direction using a thread feed motor (not shown) as a drive source.

Although not shown, the pickup 3 further includes a tracking actuator for biasing the information reading light spot with respect to the recording track of the disc 1 in the disc radial direction, and a focus actuator for moving the objective lens 5 in the optical axis direction. And are built in. The output signal of the pickup 3 is converted from a current signal to a voltage signal by an I (current) / V (voltage) amplifier 8 and further waveform-shaped by an RF equalizer circuit 9, and then a DSP (Digital Signal Processor) circuit 10. Supplied.

Next, the signal processing in the DSP circuit 10 will be described. First, the PLL asymmetry correction circuit 11 corrects asymmetry to obtain a binary signal, and a continuous clock pulse is generated by a PLL (Phase Locked Loop) configuration based on the edge of the binary signal. Is generated. here,
Asymmetry refers to a state in which the center of the eye pattern of the RF signal deviates from the center of amplitude.

Next, in the EFM demodulation circuit 12, the EF
M (Eight to Fourteen Modulation) is demodulated to become digital audio data and parity for error correction / detection, and the subcode immediately after the frame synchronization signal is demodulated. EFM demodulation circuit 12
The subcode demodulated in (1) is supplied to the controller 20 via the subcode processing circuit 13. Controller 20
Is composed of a CPU.

The data after the EFM demodulation is temporarily stored in the RAM 14, and the error correction circuit 15 performs error correction based on the error correction / detection parity. The data after the error correction is deinterleaved by the de-interleave circuit 16 by CIRC (Cross Interleave Reed-Solomon Code). The DSP circuit 10 executes various kinds of signal processing based on the system clock generated by the clock generator 17.

The data that has passed through the DSP circuit 10 is passed through the RAM control signal processing circuit 22 and has a large capacity RAM 23.
Once stored in. The data stored in the large-capacity RAM 23 is read at a normal CD player output data rate through the RAM control signal processing circuit 22, filtered by the digital filter 24, and then converted into an analog signal by the D / A converter 25. L, Rch
Is derived as the audio output of.

Here, the large capacity RAM 23 is
When a track jump occurs due to a vibration or the like,
This is used to ensure continuity of reproduced audio data and prevent skipping of sounds. In addition,
The occurrence of the track jump is detected by the controller 20. That is, the controller 20 constantly monitors the subcode supplied from the subcode processing circuit 13,
It is determined that a track jump has occurred when the subcode timecodes are discontinuous.

When a track jump occurs, the information reading light spot of the pickup 3 is returned to the position immediately before the occurrence of the track jump under the control of the controller 20, and the reproduction is restarted from that position. Further, under the control of the RAM control signal processing circuit 22, the large capacity RAM 23
A process for linking the reproduced audio data obtained after the reproduction is resumed is performed on the reproduced audio data stored immediately before the occurrence of the track jump.

The DSP circuit 10 further detects a speed difference between the rotation speed of the disk 1 and a target rotation speed on the basis of a reproduction frame synchronizing signal from the disk 1, and detects a servo error signal (speed control signal) according to the speed difference. ) Is output, a spindle / servo signal processing circuit 18 is provided. The optical system servo signal processing circuit 26 is a servo system related to the operation of the pickup 3, that is, a tracking servo system for causing the information reading light spot to follow the recording track of the disc 1, and the optical spot concerned.
Is for controlling the focus servo system for always focusing on the signal surface and the sled servo system for controlling the position of the pickup 3 in the disk radial direction.

The servo error signal from the spindle / servo signal processing circuit 18 is an LPF (low-pass filter) 2
It is supplied to the VCO (voltage controlled oscillator) 28 via 7 as its control signal. The oscillation output of this VCO 28 is
It serves as one input of the changeover switch 29. The changeover switch 29 is, for example, 1 generated by the crystal oscillator 30.
A fixed clock of 6.9344 MHz (44.1 KHz × 384) is used as the other input, and the controller 20 controls the switching to select either the oscillation output of the VCO 28 or the fixed clock of 16.9344 MHz to generate the clock. Supply to the container 17.

The clock generator 17 generates a system clock having a fixed frequency when the fixed clock of the crystal oscillator 30 is supplied, and when the oscillation output of the VCO 28 is supplied, the frequency is variable according to the oscillation output. Generates system clock. The oscillation output of the VCO 28 is further divided into 1 / M by the 1 / M frequency divider 31 and becomes one input of the phase comparator 32. Further, the fixed clock of the crystal oscillator 30 is divided into 1 / N by the 1 / N divider 33 and becomes the other input of the phase comparator 32 as a reference clock. Note that M and N are variables that can take arbitrary values, and are set to appropriate values by the controller 20.

The phase comparator 32 detects the phase difference between the frequency-divided output of the 1 / M frequency divider 31 and the frequency-divided output of the 1 / N frequency divider 33, and outputs a phase difference signal corresponding to this phase difference. Output. This phase difference signal is supplied to the spindle driver 35 as a drive signal for the spindle motor 2 via the LPF 34.
The fixed clock of the crystal oscillator 30 is RAM
Control signal processing circuit 22, digital filter 2
4 and the D / A converter 25 are supplied as clocks for processing these signals.

In the seismic resistant CD player having the above structure,
When the changeover switch 29 selects the fixed clock of the crystal oscillator 30, the system clock becomes 16.93.
It is fixed at 44 MHz. On the other hand, the changeover switch 29 is V
When the frequency division output of the CO 28 is selected, the system clock changes so that the servo error signal output from the spindle servo signal processing circuit 18 becomes zero. That is, even if the rotation speed of the disk 1 is relatively loose, the system clock changes according to the rotation speed.

This means that the center frequency of the PLL of the PLL asymmetry correction circuit 11 follows the rotation speed of the disk 1, and the rotation speed can be locked in a wide range. In other words, in the conventional reproducing circuit, the system clock is fixed and the spindle servo system is controlled so that the rotation speed of the disk 1 becomes the reference rotation speed. The spindle servo control is performed so that the reproducing circuit follows the arbitrary rotation speed.

When the changeover switch 29 selects the oscillation output of the VCO 28, the 1 / M frequency divider 31,
The reproduction speed of the disc 1 can be arbitrarily set by selecting the values of M and N of the 1 / N frequency divider 33. For example, when M = N, 1 / M frequency divider 31, 1 / N
The frequency of each frequency-divided output of the frequency divider 33 becomes equal, and is approximately 1
Double speed playback. Here, if the frequency of the oscillation output of the VCO 28 is Fa and the frequency of the fixed clock of the crystal oscillator 30 is Fb,

## EQU1 ## The relationship of Fa = (M / N) .Fb is established.

When M / N = 2, VCO
The frequency Fa of the oscillation output of 28 is the crystal oscillator 30.
The frequency becomes twice as high as the fixed clock frequency Fb, and double speed reproduction is performed. Here, as described above, since the rotation speed of the disk 1 can be controlled comparatively roughly, the RF demodulation can be correctly performed continuously as long as the rotation speed of the disk 1 changes within the range that the VCO 28 can follow. It can be carried out. For that purpose, 1 / M frequency divider 31, 1 / N frequency divider 33 M,
Each value of N may be continuously changed by the controller 20.

The controller 20 normally sets each value of M and N of the 1 / M frequency divider 31 and the 1 / N frequency divider 33 to M = N for 1 × speed reproduction to prevent disturbance such as vibration. If a track jump occurs due to this, set M / N = 2 and set 2
Double speed high speed playback. That is, the sub-code is constantly monitored during the reproduction at the 1 × speed, and the occurrence of the track jump is known by detecting that the time code of the subcode is discontinuous, and at that point, the reproduction is switched to the 2 × speed reproduction. The reproduction speed in the high speed reproduction mode is not limited to the double speed.

When a track jump occurs, the controller 20 searches for the last continuous subcode,
The RAM control signal processing circuit 22 controls the pickup 3 to the position immediately before the occurrence of the track jump, controls to restart the reproduction from that position, and performs the linking process for connecting the reproduced audio data from the position.
To control. Here, the reason why the reproduction is performed at the double speed when the track jump occurs will be described.

When, for example, 4 Mbits are used as the large capacity RAM 23, the speed at which the large capacity RAM 23 is charged with data is the difference between the speed at which the data is written to the large capacity RAM 23 and the speed at which the data is read (2 times-1 times). Becomes That is, the disk 1 has a sampling frequency of 4
Since the digital signal is recorded at 4.1 KHz and the quantization number 16-bit straight line,

[Equation 2] 4,194,304 ^{bits / (} 44.1 ^KHz × 2)
^{(L, R)} × 16) ^bit × 1 = 2.97 [seconds] Therefore, it takes about 3 seconds to charge the large capacity RAM 23.

Even if the data is not reproduced from the disc 1 due to the occurrence of the track jump, this 3 second time
It is the time when the sound can be played back without interruption. This time has no practical problem, and is determined by the memory capacity of the large-capacity RAM 23 and the reproduction speed in the high-speed mode (double speed in this example), that is, the reproduction data rate. During this 3 seconds, linking processing for maintaining continuity of reproduced audio data and data charging of the large capacity RAM 23 are performed. When the overflow signal is output from the RAM control signal processing circuit 22 during the 2 × speed reproduction, the controller 20 switches the reproduction mode to the 1 × speed reproduction in response to the overflow signal.

By the way, when the reproduction mode is the double speed reproduction, the data writing to the large capacity RAM 23 is performed at a higher speed than the reading, so that the large capacity RAM 23 immediately overflows.
It is necessary to constantly monitor the amount of data stored in 23. The data amount of the large capacity RAM 23 is monitored by the RAM
This is performed by the control signal processing circuit 22.

That is, the RAM control signal processing circuit 22 recognizes the final address of the data written in the large-capacity RAM 23 as the definite address, always recognizes the address of the read data as the address 0, and recognizes the recognized definite address. It is always given to the controller 20. Further, the amount of data is monitored based on this fixed address, and an overflow signal is supplied to the controller 20 when the amount of data exceeds a predetermined set amount.

The controller 20 recognizes the definite address given from the RAM control signal processing circuit 22 as a definite subcode in correspondence with the subcode. The controller 20 further switches the changeover switch 29 when the rotation speed of the disc 1 reaches the target rotation speed when the reproduction mode is changed from 1 × speed reproduction to 2 × speed reproduction or from 2 × speed reproduction to 1 × speed reproduction. To select the fixed clock of the crystal oscillator 30.
According to this, since the signal can be synchronized with the D / A converter 25, an audio output without wow and flutter can be derived.

In a normal CD player, the spindle driver 35 applies an acceleration voltage / deceleration voltage to the spindle motor 2 to control the rotation speed of the disk 1 to a target rotation speed. Then, when the rotation speed of the disk 1 becomes close to the target rotation speed, a predetermined voltage is applied to bring the disk 1 into a locked state. Here, the acceleration voltage is a voltage on the positive side with respect to the predetermined voltage,
The deceleration voltage is a negative voltage with respect to the predetermined voltage.

However, in the seismic resistant CD player according to the present invention, as described above, since the control of the spindle servo system can be rough, the deceleration component of the phase comparator 32 is largely cut by the spindle driver 35 to decelerate. At this time, the above-mentioned predetermined voltage is applied. According to this, when the spindle motor 2 is driven, energy consumption can be suppressed by the amount of cutting the deceleration component, so that the power consumption of the player can be reduced.

In the above embodiment, the seismic resistant CD is used.
The case where it is applied to a player has been described.
Also in the D player, by applying the present invention, the data can be read even when the rotation speed of the disc 1 is not constant, which is useful for high speed access. Further, in the above-described embodiment, the case where the present invention is applied to the CD player has been described, but the present invention is not limited to this, and the present invention can also be applied to other disc players that reproduce MD and CD-ROM discs. is there.

[0038]

As described above, according to the first aspect of the present invention, the frequency of the oscillation output of the VCO (oscillation means) is controlled according to the speed control signal of the disk, while the oscillation output is processed by the signal. By supplying the circuit as a system clock and controlling the rotational speed of the disk according to the phase difference of the oscillation output from the reference clock, the system clock changes so that the speed control signal becomes 0. When the reproduction mode is switched between, for example, 1 × speed and 2 × speed, the spindle servo system can be locked even during the period in which the rotational speed changes, so that information can be read from the disc during this period as well.

As a result, in the seismic resistant disk player, only when a track jump occurs due to a disturbance such as a vibration, the reproduction mode is set to the double speed reproduction to quickly perform the data charge to the large capacity memory. By the 1 × speed reproduction, the power consumption of the player can be significantly reduced, and the continuity of the reproduction data when the track jump occurs can be secured.
Further, since there is no unlock period of the spindle servo system and data can be stored in the large-capacity memory even during the transition of the rotation speed, it is not necessary to use a large-capacity memory as the large-capacity memory, and an inexpensive memory is used. Therefore, the earthquake-resistant disc player can be realized at low cost.

According to the second aspect of the present invention, the oscillation output of the VCO and the reference clock are each divided by a variable division ratio, and the rotational speed of the disk is controlled according to the phase difference of each division output. By doing so, it is possible to arbitrarily set the reproduction speed such as 1 × speed reproduction or 2 × speed reproduction by appropriately selecting each frequency division ratio. According to the invention of claim 3,
A selection means for selecting either the VCO oscillation output or the reference clock is provided, and when the rotational speed of the disk is roughly controlled, the VCO oscillation output is selected and when the rotational speed reaches the target rotational speed, the reference clock is selected. Since the signal can be synchronized with the D / A converter by selecting, it is possible to derive an audio output without wow and flutter.

[Brief description of drawings]

FIG. 1 is a block diagram of a control system showing an embodiment of the present invention applied to a seismic resistant CD player.

[Explanation of symbols]

1 disk 2 spindle motor 3 optical pickup 10 DSP circuit 12 EFM demodulation circuit 15 error correction circuit 18 spindle / servo signal processing circuit 20 controller 22 RAM control signal processing circuit 23 large capacity RAM 26 optical system servo signal processing circuit 28 VCO (voltage Control oscillator) 29 Changeover switch 30 Crystal oscillator 31 1 / M frequency divider 32 Phase comparator 33 1 / N frequency divider

Claims (3)

[Claims] 1. A signal processing means for processing a reproduction signal from a disc, detecting a speed difference of a rotation speed of the disc with respect to a target rotation speed, and outputting a speed control signal according to the speed difference, and an oscillation output. The oscillation means supplies the signal processing means as a system clock, and the frequency of the oscillation output changes according to the speed control signal, and detects the phase difference of the oscillation output with respect to the reference clock to detect the phase difference. A disc player, comprising: a speed control means for controlling the rotation speed of the disc. 2. The speed control means divides the oscillation output by a variable frequency division ratio, and a second frequency dividing means divides the reference clock by a variable frequency division ratio. 2. The disc player according to claim 1, further comprising: means and a detection phase comparison means for detecting a phase difference between the frequency-divided outputs of the first and second frequency dividing means. 3. The disc player according to claim 1, further comprising a selection unit that selects one of the oscillation output and the reference clock and supplies the selected signal as a system clock to the signal processing unit.