JP2000163760A - Optical disk drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate a proper count number and to improve the precision of rough seeking by reducing or removing the high-frequency noise component included in a signal corresponding to the number of tracks that an optical head has passed when the optical head is moved to a target position on a disk. SOLUTION: A tracking error signal is inputted to a count signal generating circuit 60b of a count signal generating device 60 and a high-pass filter 71 removes the low-frequency component included in the tracking error signal. Then a comparator 74 binarizes the tracking error signal outputted by the high-pass filter 71. The count signal outputted by the comparator 74 is supplied to a control means, which counts the pulses of the count signal. Thus, when the optical disk is moved to a target track (target address), the noise included in the tracking error signal is reduced or removed, so the tracking error signal can accurately and securely be binarized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an optical disk device.

[0002]

2. Description of the Related Art There is known an optical disk device for reproducing or recording / reproducing a read-only optical disk such as a CD-ROM or a recordable / reproducible optical disk such as a CD-R or CD-RW.

[0003] This optical disk device includes a rotation drive mechanism for mounting and rotating an optical disk, an optical head (optical pickup) capable of moving in a radial direction with respect to the mounted optical disk, and a method for moving the optical head in a radial direction. It has an optical head moving mechanism provided with a sled motor for moving, and a count signal generating circuit.

The optical head is provided with an optical head body (optical pickup base) having a laser diode and a divided photodiode, and can be moved in the radial direction and the optical axis direction (focus direction) of the optical disk by the optical head body. And an actuator for moving the objective lens in the optical axis direction and the radial direction.

FIG. 11 is a circuit diagram showing a count signal generation circuit of a conventional optical disk device.

As shown in FIG. 1, a count signal generation circuit (count signal generation device) 90 includes a high-pass filter 91 including a capacitor 92 and a resistor 93, and a comparator connected to the output side of the high-pass filter 91. 94
And resistors 95, 96, 97 and 98.

[0007] A reference voltage V _ref is applied to the node 105. That is, the non-inverting input terminal 9 of the comparator 94
42 has a reference voltage V via resistors 95 and 96.
_ref is input.

A signal (voltage) output from the high-pass filter 91 is supplied to an inverting input terminal 941 of the comparator 94.
Is entered.

A power supply voltage V _DD is applied to the node 106.

[0010] A tracking error signal (TE) is input to the count signal generation circuit 90, and the tracking error signal is supplied to an inverting input terminal 941 of a comparator 94 after a low frequency component is removed by a high-pass filter 91. It is input and binarized by the comparator 94. That is, a count signal (TC) is generated and output.

It should be noted that one cycle (one waveform) of the tracking error signal, ie, one pulse of the count signal originally passed (crossed) the optical head (objective lens).
This corresponds to one pitch of a track.

In such an optical disk apparatus, the optical head is moved to a target track (target address), and information (data) is recorded (written) on the optical disk while performing focus control, tracking control, and the like on the target track. And reproduction (reading) of information from the optical disk.

When moving the optical head to the target track, first, the thread motor is driven to move the entire optical head to the vicinity of the target track (coarse seek is performed).

That is, an acceleration pulse voltage is applied to the sled motor to move the optical head in the radial direction. At this time, as described above, the count signal generation circuit 90 binarizes the tracking error signal to generate a count signal. The number of pulses of the count signal is counted, whereby the number of tracks that the optical head has passed (traversed) is obtained.
When the number of tracks (count value) reaches a predetermined value, a deceleration pulse voltage is applied to the sled motor to start braking the sled motor. Thereby, after a predetermined time,
The optical head stops.

Next, the address where the optical head is located is read, and the coarse seek is repeated until the number of tracks from the track where the optical head is located to the target track is equal to or less than a predetermined value.

When the number of tracks from the track where the optical head is located to the target track becomes equal to or less than a predetermined value, the actuator is driven to move the objective lens in the radial direction. When the optical head is driven to follow the objective lens, the optical head is moved to a target track (performs a precise seek).

However, in the above-mentioned conventional optical disk device, when the optical head is moved to the target track,
In particular, during the initial period (when the moving speed of the optical head is slow), as shown in FIG. 12A, the tracking error signal contains a large amount of high-frequency noise components (noise). As shown in FIG. 12B, there is a disadvantage that the number of tracks that have passed through the optical head cannot be accurately obtained.

That is, the level of the count signal should be high (H) originally, but it should be low (L) due to noise, or the level of the count signal should be low originally. In some cases, as shown in FIG. 12, when the optical head passes through one track, six count signal pulses 200 are generated, and one track is recognized as six tracks, as shown in FIG. May be done. This is more remarkable as the rotation speed (rotation speed) of the optical disk is lower.

Therefore, the accuracy of the coarse seek is poor, and when the optical head is moved to the target track, the coarse seek may be performed many times, and it takes a long time to move the optical head to the target track (target address). (Access time is long).

[0020]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the time (access time) required to move the optical head to a target track (target address) by accurately obtaining the number of tracks that the optical head has passed. An object of the present invention is to provide an optical disk device that can be shortened.

[0021]

This and other objects are achieved by the present invention which is defined below as (1) to (11).

(1) An optical disk device having a rotation drive mechanism for mounting and rotating an optical disk and an optical head, and recording and / or reproducing the optical disk via the optical head. When moving in the radial direction of the optical disc, a signal generation circuit that generates a signal corresponding to the number of tracks that the optical head has passed, and the number of tracks that the optical head has passed based on a signal from the signal generation circuit. An optical disc device comprising: a count signal generation circuit that generates a count signal for counting; and a high-frequency removal circuit that removes a high-frequency component included in a signal from the signal generation circuit.

(2) a filter-on mode in which a portion of the high-frequency removing circuit for removing the high-frequency component functions;
The optical disc device according to (1), further comprising a setting unit that sets one of a filter-off mode in which a portion of the high-frequency removing circuit that removes the high-frequency component does not function.

(3) The setting means sets the filter on mode or the filter off mode in accordance with the degree of progress of the movement of the optical head when moving the optical head in the radial direction of the optical disk. The optical disk device according to the above (2), which is configured.

(4) The setting means includes: a predetermined period for moving the optical head in a radial direction of the optical disk;
The optical disk device according to (2), wherein the optical disk device is configured to set the filter-on mode.

(5) The optical disk device according to (4), wherein the predetermined period is an initial period when the optical head is moved in a radial direction of the optical disk.

(6) The optical disk device according to (4), wherein the predetermined period is a period from the start of the movement of the optical head to the stabilization of the moving speed of the optical head.

(7) The cut-off frequency of the high-frequency removing circuit is higher than the frequency of a signal corresponding to the number of tracks passed by the optical head and lower than the frequency of a high-frequency noise component included in the signal. The optical disc device according to any one of (1) to (6).

(8) The optical disc device according to any one of (1) to (7), wherein the cutoff frequency of the high-frequency removing circuit can be set to a plurality.

(9) The selection of the cut-off frequency of the high-frequency removing circuit is made according to the degree of progress of the movement of the optical head when the optical head is moved in the radial direction of the optical disk. The optical disk device according to (8).

(10) The rotation drive mechanism is configured to be able to rotate the optical disk at a plurality of rotation speeds, and the cutoff frequency of the high frequency removing circuit is selected according to the rotation speed. The optical disk device according to the above (8), which is configured to be configured as described above.

(11) The optical disc device according to any one of (1) to (10), wherein the signal corresponding to the number of tracks passed by the optical head is a tracking error signal.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical disk drive according to the present invention will be described in detail based on a preferred embodiment shown in the accompanying drawings.

FIG. 1 is a block diagram showing a circuit configuration (main part) of a first embodiment of the optical disk apparatus of the present invention, and FIG.
FIG. 2 is a plan view showing the first embodiment (with the casing removed) of the optical disc device of the present invention.

The optical disk device 1 shown in these figures is a device for reproducing an optical disk (CD-ROM) 2.

A spiral track is formed on the optical disk 2.

The optical disk device 1 has a rotation drive mechanism for mounting and rotating the optical disk 2. The rotation drive mechanism mainly includes a spindle motor 11 for rotating the turntable, a driver 23 for driving the spindle motor 11, a turntable 13 fixed to the rotation shaft 12 of the spindle motor 11, and the optical disk 2 mounted thereon. It is composed of

The optical disk apparatus 1 moves in the radial direction of the optical disk 2 (radial direction of the turntable 13) with respect to the loaded optical disk 2 (turntable 13), that is, in the direction of arrow A in FIG. An optical head (optical pickup) 3 to be obtained; an optical head moving mechanism for moving the optical head 3 in the radial direction;
Amplifier IC 40 and servo processor (DSP) 51
, A decoder 52, and a memory (for example, a RAM or the like) 5
3, a count signal generating device 60 composed of a filter switching circuit (high frequency removing circuit) 60a and a count signal generating circuit 60b, and a casing (not shown) for accommodating these components. Hereinafter, the radial direction of the optical disk 2 is simply referred to as “radial direction”.

The optical head 3 has an optical head main body (optical pickup base) 31 having a laser diode (light source) 5 and a divided photodiode (light receiving section) 6, and an objective lens (condensing lens) 32. I have.

The objective lens 32 is supported by a suspension spring (not shown) provided on the optical head body 31.
The radial direction and the objective lens 3 are
2 (in the direction of the rotation axis of the optical disc 2 (turntable 13)). When the objective lens 32 deviates from its neutral position (middle point), the objective lens 32 is urged toward the neutral position by the restoring force of the suspension spring. Hereinafter, the optical axis direction of the objective lens 32 is simply referred to as “optical axis direction”, and the rotation axis direction of the optical disk 2 is simply referred to as “rotation axis direction”.

The optical head 3 is an optical head main body 3.
1 has an actuator 4 for moving the objective lens 32. The actuator 4 includes a tracking actuator for moving the objective lens 32 in the radial direction with respect to the optical head main body 31 and a focus actuator for moving the objective lens 32 in the optical axis direction (rotation axis direction).

The actuator 4, that is, the tracking actuator and the focus actuator are each driven by a driver 21.

The optical head body 31 is formed with three support portions (sliders) 311 which slide along the guide shaft 16 described later.

The optical head moving mechanism mainly includes a sled motor 7 and a driver 22 for driving the sled motor 7.
A lead screw (worm gear) 81 fixed to the rotation shaft 8 of the thread motor 7, a reduction gear 14, a rack gear 15, a pair of guide shafts 16 for guiding the optical head 3, and the three supports described above. (Slider) 311.

The reduction gear 14 comprises a worm wheel 141 meshing with the lead screw 81 and a pinion gear 142 fixed concentrically to the worm wheel 141 and having a smaller diameter than the worm wheel 141.

The rack gear 15 meshes with the pinion gear 142 and is fixed to the optical head main body 31.

As described above, the optical head 3 supports the pair of guide shafts 16, 16 with the support portions 31.
1 movably supported.

The thread motor 7 is driven, and its rotating shaft 8
When the lead screw 81 rotates in a predetermined direction,
The worm wheel 141 and the pinion gear 142 rotate in a predetermined direction, and the rack gear 15 and the pinion gear 142
Thus, the rotational movement of the pinion gear 142 is converted into a linear movement of the optical head 3, and the optical head 3 moves in a predetermined direction along the guide shaft 16.

When the rotation shaft 8 of the thread motor 7 and the lead screw 81 rotate in the opposite direction, the optical head 3 moves along the guide shaft 16 in the opposite direction.

The control means 9 is usually constituted by a microcomputer (CPU), and comprises an optical head 3 (actuator 4, laser diode 5, etc.), a thread motor 7, a spindle motor 11, an RF amplifier IC 40, a servo processor 51, and a decoder 52. , The memory 53, the count signal generator 60, and the like. The main function of the setting means is achieved by the control means 9.

An external device (for example, a computer) is detachably connected to the optical disk device 1 via an interface control unit (not shown).
And an external device.

Next, the count signal generator 60 will be described.

FIG. 3 is a circuit diagram showing a configuration example of the count signal generation device 60.

As shown in the figure, the count signal generating device 60 includes a filter switching circuit (high-frequency removing circuit) 60a.
And a count signal generation circuit 60b connected to the output side of the filter switching circuit 60a.

The filter switching circuit 60a comprises a low-pass filter 61 composed of a resistor 62 and a capacitor 63.
, A transistor (selection switch) 64, and a resistor 65.

The terminal 66 is connected to the output side of the RF amplifier IC 40, and the terminal 67 is connected to the output side of the control means 9.

The control means 9 inputs a filter switching signal (voltage) to the base (gate) of the transistor 64, and according to the filter switching signal, a filter-on mode in which the low-pass filter 61 functions and a filter in which the low-pass filter 61 does not function. Set to one of the off modes.

That is, when the level of the filter switching signal is low (L), the transistor 64 is turned off, and the filter is turned off.

When the level of the filter switching signal is high (H), the transistor 64 is turned on,
Set to filter-on mode.

The cut-off frequency of the filter switching circuit 60a, that is, the cut-off frequency of the low-pass filter 61 is higher than the frequency of a tracking error signal described later, and a high-frequency noise component (noise) included in the tracking error signal. Is set lower than the frequency.

The count signal generation circuit 60b includes a high-pass filter 7 composed of a capacitor 72 and a resistor 73.
1, a comparator (binarization circuit) 74 connected to the output side of the high-pass filter 71, and resistors 75, 76, 77 and 78.

The reference voltage _Vref is applied to the node 85. That is, the non-inverting input terminal 74 of the comparator 74
2 has a reference voltage V _ref via resistors 75 and 76.
Is entered.

A signal (voltage) output from the high-pass filter 71 is supplied to an inverting input terminal 741 of the comparator 74.
Is entered.

A power supply voltage (drive voltage) _VDD is applied to the node 86 via a resistor 78. And terminal 7
9 is connected to the input side of the control means 9.

The cut-off frequency of the high-pass filter 71 is set lower than the frequency of a tracking error signal described later.

Next, the operation of the optical disk device 1 will be described.

The optical disk apparatus 1 moves the optical head 3 to a target track (target address), and performs focus control, tracking control, sled control, rotation speed control (rotation speed control), and the like on the target track. 2 is read (reproduced) from the information (data).

At the time of reproduction, a laser beam is emitted from the laser diode 5 of the optical head 3 onto a predetermined track of the optical disk 2. This laser light is reflected by the optical disk 2, and the reflected light is received by the split photodiode 6 of the optical head 3.

The split photodiode 6 outputs a current corresponding to the amount of received light.
-V amplifier (current-voltage conversion unit)
Output from the optical head 3.

The voltage (detection signal) output from the optical head 3 is input to an RF amplifier IC 40, and the RF amplifier IC 40 performs addition, amplification, and the like to obtain an HF signal.
An (RF) signal is generated. This HF signal is an analog signal corresponding to pits and lands written on the optical disc 2.

The HF signal is input to a servo processor 51, which binarizes the HF signal,
M (Eight to Fourteen Modulation) demodulation, decoding (conversion) to data (DATA signal) of a predetermined format, and input to the decoder 52.

This data is supplied to a decoder 52,
The data is decoded into data of a predetermined format for communication (transmission) and transmitted to an external device (for example, a computer) via an interface control unit (not shown).

The tracking control, sled control and focus control in the above-described reproducing operation are performed as follows.

As described above, the signal (voltage) after current-voltage conversion from the divided photodiode 6 of the optical head 3
Is input to the RF amplifier IC 40.

The RF amplifier IC 40 receives the current-voltage converted signal from the divided photodiode 6 based on
A tracking error signal (TE) (voltage) is generated.

The tracking error signal is output from the objective lens 3
2 is a signal indicating the amount of displacement in the radial direction, that is, the magnitude and direction of the displacement of the objective lens 32 in the radial direction from the center of the track (the amount of displacement from the center of the track).

The tracking error signal is input to the servo processor 51. The servo processor 51 performs predetermined signal processing such as phase inversion and amplification on the tracking error signal, thereby generating a tracking servo signal (voltage). A predetermined drive voltage is applied to the actuator 4 via the driver 21 based on the tracking servo signal, and the objective lens 32 moves toward the center of the track by driving the actuator 4. That is, tracking servo is applied.

The drive of the actuator 4 alone has a limitation in causing the objective lens 32 to follow the track. To cover this, the thread motor 7 is driven via the driver 22 to move the optical head main body 31 to the object. Control is performed such that the objective lens 32 returns to the neutral position by moving in the same direction as the direction in which the lens 32 has moved (thread control is performed).

The RF amplifier IC 40 generates a focus error signal (FE) (voltage) based on the signal after the current-voltage conversion from the divided photodiode 6.

The focus error signal is transmitted to the objective lens 32
In the optical axis direction (rotation axis direction), that is, the objective lens 3 in the optical axis direction (rotation axis direction) from the in-focus position.
2 is a signal indicating the magnitude and direction (deviation amount of the objective lens 32 from the in-focus position) of the deviation of the objective lens 32.

The focus error signal is input to the servo processor 51. The servo processor 51 performs predetermined signal processing such as phase inversion and amplification on the focus error signal, thereby generating a focus servo signal (voltage). A predetermined drive voltage is applied to the actuator 4 via the driver 21 based on the focus servo signal, and the objective lens 32 moves toward the focus position by driving the actuator 4. That is, focus servo is applied.

When the optical head 3 (objective lens 32) is moved to a target position on the optical disk 2, that is, a target track (target address), track jump control is performed. In this track jump control, the drive of the sled motor 7 and the drive of the actuator 4 are respectively controlled, and the optical head 3 (objective lens 32) is controlled by a coarse seek (rough search), a precision seek (fine search), or a combination thereof. To the target track (target address).

Here, the optical head 3 (objective lens 32)
When the number of tracks (the number of tracks from the current track to the target track) through which the optical head 3 (objective lens 32) passes when the is moved from the current track (access start track) to the target track, that is, If it is equal to or greater than the preset reference value (threshold),
A coarse seek is performed. Hereinafter, the number of tracks through which the optical head 3 (objective lens 32) passes when the optical head 3 (objective lens 32) is moved from the current track (access start track) to the target track is simply referred to as "target passing track number". .

If the optical head 3 (objective lens 32) is not positioned on the target track at the end of the coarse seek, then a precise seek is performed. The lens 32) is moved to the target track.

When the number of target passing tracks is relatively small, that is, when the number of target passing tracks is less than the reference value, precision seek is performed, and the optical head 3 (objective lens 32) moves to the target track by the precision seek. Is done. Hereinafter, the coarse seek and the fine seek will be described.

In the coarse seek, a sled motor drive signal (sled motor drive voltage) is input to the driver 22.
As a result, the thread motor 7 is driven and the optical head 3
Starts moving toward the target track (accelerated).

After a lapse of a predetermined time, the moving speed (speed) of the optical head 3 converges to a substantially predetermined value (constant speed).

On the other hand, in the RF amplifier IC 40, a tracking error signal is generated, and the count signal generation device 60
Is input to This tracking error signal is binarized by the count signal generation device 60, and a binarized signal of the tracking error signal, that is, the count signal (T
C) is obtained. Note that this count signal generation device 60
Will be described in detail later.

One waveform (one cycle) of the tracking error signal corresponds to one pitch of a track that has passed (traversed) by the optical head 3 (objective lens 32). It is used for counting.

In the optical disk device 1, the number of pulses of the count signal is counted from the start of the coarse seek by a counter (not shown) built in the control means 9.

When this count value (number of pulses) reaches a predetermined value, that is, the number of tracks up to the target track (hereinafter simply referred to as the "number of remaining tracks") N (= the number of target passing tracks-the count value) ) Becomes a predetermined value n ₁ , a brake signal (brake voltage) having a sign (positive or negative) opposite to the sled motor drive signal (sled motor drive voltage) is input to the driver 22, whereby the sled motor is driven. 7 is braked.

That is, the moving speed of the optical head 3 decreases (the optical head 3 decelerates), and after a lapse of a predetermined time, the optical head 3 stops at or near the target track.

[0093] Incidentally, the _{n 1} is preset.

In the precision seek, the actuator 4
Is driven to move the objective lens 32 in the radial direction, and at the same time, the thread motor 7 is driven to drive the optical head main body 3.
1 follows the objective lens 32, thereby moving the optical head 3 to the target track.

Next, the operation of the count signal generator 60 will be described.

The control means 9 sets the filter on mode or the filter off mode in accordance with the degree of the movement of the optical head 3 when moving the optical head 3 to the target track (when moving the optical head 3 in the radial direction). Hereinafter, this will be described in detail.

The control means 9 sets the level of the filter switching signal to the high level for a predetermined period when the optical head 3 is moved to the target track (when it is moved in the radial direction). Thus, the transistor 64 is turned on for the predetermined period, and the low-pass filter 61 functions. That is,
The filter-on mode is set for the predetermined period.

The predetermined period is an initial period when the optical head 3 is moved to the target track, that is, a period from the start of the movement of the optical head 3 until the moving speed of the optical head 3 is stabilized (the period of the movement of the optical head 3). (Acceleration range period). For example, 5 minutes from the start of the movement of the optical head 3
It is preferably about 20 msec.

Since the moving speed of the optical head 3 is relatively slow (small) during the predetermined period, a high-frequency noise component (noise) is included in the tracking error signal generated by the RF amplifier IC 40 as shown in FIG. Therefore, the noise is removed by the low-pass filter 61.

The control means 9 sets the level of the filter switching signal to a low level immediately after the predetermined period when the optical head 3 is moved to the target track. This allows
The transistor 64 is turned off, one end of the capacitor 63 is cut off, and the low-pass filter 61 does not function. That is, the mode is set to the filter off mode.

Since the moving speed of the optical head 3 is relatively fast (large) during the constant speed range of the optical head 3, the tracking error generated by the RF amplifier IC 40 as shown in FIG. The signal does not contain much high-frequency noise components (noise), and therefore, it is not necessary to remove the noise by the low-pass filter 61. Further, since the frequency of the tracking error signal and the frequency of the high-frequency noise component (noise) are close to each other, even if the low-pass filter 61 attempts to remove only the noise, the tracking error signal may also be removed. The low-pass filter 61 is disabled.

As described above, the level of the filter switching signal from the control means 9 is switched from the low level to the high level at the start of the coarse seek, and is set to the filter on mode.

FIG. 4 generated by the RF amplifier IC 40
The tracking error signal (TE) shown in (a) is input to the count signal generation device 60,
1 removes high-frequency noise components (noise) included in the tracking error signal as shown in FIG.

Next, the tracking error signal output from the low-pass filter 61 is input to the count signal generation circuit 60b, and the high-pass filter 71 removes low frequency components included in the tracking error signal.

Next, the tracking error signal output from the high-pass filter 71 is input to the inverting input terminal 741 of the comparator 74, and is binarized by the comparator 74. That is, as shown in FIG. 4C, a count signal (TC) is generated and output.

The count signal output from the comparator 74 is input to the control means 9, and the number of pulses of the count signal is counted by the control means 9 as described above.

Then, as described above, the level of the filter switching signal from the control means 9 is set immediately after the predetermined period.
The level is switched from the high level to the low level, and the filter off mode is set.

FIG. 4 generated by the RF amplifier IC 40
The tracking error signal shown in (a) is input to the count signal generation device 60, is input to the count signal generation circuit 60b via the resistor 62 of the filter switching circuit 60a, and is included in the tracking error signal by the high-pass filter 71. Low frequency components are removed.

Next, the tracking error signal output from the high-pass filter 71 is input to the inverting input terminal 741 of the comparator 74, and is binarized by the comparator 74. That is, as shown in FIG. 5B, a count signal is generated and output.

The count signal output from the comparator 74 is input to the control means 9, and the number of pulses of the count signal is counted by the control means 9 as described above.

As described above, according to the optical disk device 1, when the optical head 3 is moved to the target track (target address), the noise included in the tracking error signal is reduced or eliminated. Can be accurately and reliably binarized, whereby the number of tracks passed by the optical head 3 can be accurately counted.

As a result, the accuracy of the coarse seek is improved (variation in the stop position of the optical head 3 during the coarse seek is suppressed), and the time required for moving the optical head 3 to the target track, ie, the access time (Seek time) can be reduced.

Further, in the optical disc apparatus 1, the period from the start of the coarse seek to the time when the moving speed of the optical head 3 is stabilized is set to the filter-on mode. After that, the frequency of the tracking error signal and the noise Since the filter-off mode is set when the frequency approaches, the removal of the tracking error signal by the low-pass filter 61 can be prevented, and the tracking error signal is more accurately and reliably binarized. Thus, the number of tracks passed by the optical head 3 can be counted more accurately.

Next, a description will be given of a second embodiment of the optical disk apparatus according to the present invention. The description of common points with the optical disc device 1 of the first embodiment will be omitted, and the main differences will be described.

FIG. 6 is a circuit diagram showing a configuration example of a count signal generation device in a second embodiment of the optical disk device of the present invention.

As shown in the figure, the count signal generating device 60 in the second embodiment includes a filter switching circuit (high frequency removing circuit) 60a and a count signal generating circuit 60b connected to the output side of the filter switching circuit 60a. It is composed of

The filter switching circuit 60a sets the cut-off frequency of the low-pass filter to f ₁ , f ₂ and f ₃ (where
It is configured such that any one of f ₁ <f ₂ <f ₃ ) can be set.

That is, the filter switching circuit 60a comprises a resistor 62, a first capacitor 82, a first transistor (selection switch) 83, a resistor 84, and a second capacitor 8.
7, a second transistor (selection switch) 88 and a resistor 89.

The level of the first filter switching signal (voltage) inputted from the control means 9 to the base (gate) of the first transistor 83 and the level inputted to the base (gate) of the second transistor 88 from the control means 9 When both the level of the second filter switching signal (voltage) is low, the first transistor 83 and the second transistor 88
Are both turned off, and the mode is set to the filter off mode.

When at least one of the level of the first filter switching signal and the level of the second filter switching signal is at a high level, a filter-on mode is set.

That is, when the level of the first filter switching signal and the level of the second filter switching signal are both high, both the first transistor 83 and the second transistor 88 are turned on, and the filter is turned on. Mode is set. In this case, the resistor 62 and the first capacitor 82
And in the second capacitor 87, the low pass filter is configured cutoff frequency f _1.

When the level of the first filter switching signal is high and the level of the second filter switching signal is low, the first transistor 83 is turned on and the second transistor 83 is turned on.
Is turned off, and the filter is set to the filter on mode. In this case, the resistor 62 and the first capacitor 8
2 and, in the low-pass filter is configured cutoff frequency f _2.

When the level of the first filter switching signal is low and the level of the second filter switching signal is high, the first transistor 83 is turned off and the second transistor 83 is turned off.
Transistor 88 is turned on, and a filter-on mode is set. In this case, the resistor 62 and the second capacitor 8
In 7, a low-pass filter is composed of the cutoff frequency f _3.

The terminal 66 is connected to the output side of the RF amplifier IC 40, and the terminals 67 and 68 are connected to the output side of the control means 9, respectively.

The count signal generation circuit 60b is the same as the count signal generation circuit 60b in the first embodiment.
Therefore, the description is omitted.

Next, the operation of the optical disk device 1 according to the second embodiment will be described.

In the optical disc apparatus 1, the cutoff frequency of the filter switching circuit 60a is selected according to the degree of movement of the optical head 3 when moving the optical head 3 to a target track (when moving the optical head 3 in the radial direction). Done.

As shown in Table 1 below, the optical head 3 was
Early period when moving to the target track, that is, light
Moving speed of the optical head 3 from the start of moving the optical head 3
The period until stabilization (the period of the acceleration range of the optical head 3)
The optical head 3 is divided into three periods of 1/3.
Of the first one-third of the acceleration range (first period)
Means that the cutoff frequency is f₁Is set to the next 1/3 period
(The second period), the cutoff frequency is f₂Set to last
遮断 (third period), the cutoff frequency is f ₃To
Is set. That is, the moving speed of the optical head 3 is high.
The lower the frequency, the higher the cutoff frequency is set. In addition, optical
The period after the end of acceleration of the head 3 (fourth period),
That is, the period after the constant speed range of the optical head 3 is as described above.
The filter is turned off.

[0129]

[Table 1]

As described above, according to the optical disk device 1, when the optical head 3 is moved to the target track, similarly to the optical disk device 1 of the first embodiment described above.
Since the noise included in the tracking error signal is reduced or eliminated, the tracking error signal can be accurately and reliably binarized.
Can be accurately counted.
Therefore, the accuracy of the coarse seek is improved, and the access time can be shortened. In addition, the period from the start of the coarse seek to the time when the moving speed of the optical head 3 is stabilized is set to the filter-on mode, and then to the filter-off mode, so that the tracking error signal is removed by the low-pass filter. Can be prevented.

The frequency of the tracking error signal is higher as the moving speed of the optical head 3 is higher.
In the optical disk device 1, the cutoff frequency of the filter switching circuit 60a is set higher as the moving speed of the optical head 3 is higher, so that only noise included in the tracking error signal can be reduced or eliminated more reliably. .

In the above embodiment, the time of the first period, the time of the second period, and the time of the third period are all equal. However, in the present invention, any one of these is used. Only the time of the period may be different from the time of the other two periods, or the time of the first period, the time of the second period, and the time of the third period may all be different. Good.

In the above embodiment, the number of cut-off frequencies that can be set by the filter switching circuit 60a is three (f ₁ , f _1
2 , f ₃ ), in the present invention, the number of cut-off frequencies that can be set in the filter switching circuit (high-frequency elimination circuit) is 2
Or four or more.

When the number of cut-off frequencies that can be set in the filter switching circuit 60a is set to four or more, for example,
In addition to the pair of the first capacitor 82 and the first transistor 83 and the pair of the second capacitor 87 and the second transistor 88 in the above embodiment, at least one pair of a capacitor and a transistor (switch) is further provided.
Only need to be connected in parallel.

Next, a description will be given of a third embodiment of the optical disk apparatus according to the present invention. The description of the common points with the optical disc device 1 of the second embodiment will be omitted, and the main differences will be described.

The optical disk device 1 of the third embodiment has a data read speed (reproduction speed), that is, the optical disk 2
The rotation speed (rotation speed) of the optical disk 2 when reading data (signal) from the disk is set to three stages of rotation speed, ie, 1 × speed,
It is configured such that it can be set to one of 2 × speed and 4 × speed.

The 2 × speed and the 4 × speed refer to
The normal speed is defined as a reference rotation speed (reference rotation speed), and the rotation speed is twice or four times the reference rotation speed.

The rotation drive mechanism rotates the optical disk 2 at the set rotation speed not only during reproduction but also when moving the optical head 3 to a target track.

The filter switching circuit 60a of the count signal generator 60 sets the cut-off frequencies of the low-pass filter to f ₄ , f ₅ and f ₆ (where f ₄ <f ₅ <f ₆ ).
Is configured to be able to be set to any of the following.

As shown in FIG. 6, when the level of the first filter switching signal and the level of the second filter switching signal are both low, the first transistor 83 and the second transistor
Are turned off, and the filter is set to the filter off mode.

When both the level of the first filter switching signal and the level of the second filter switching signal are high, both the first transistor 83 and the second transistor 88 are turned on, and the filter is turned on. Mode is set. In this case, a resistor 62, between the first capacitor 82 and second capacitor 87, a low-pass filter is constituted of cut-off frequency f _4.

When the level of the first filter switching signal is high and the level of the second filter switching signal is low, the first transistor 83 is turned on and the second transistor 83 is turned on.
Is turned off, and the filter is set to the filter on mode. In this case, the resistor 62 and the first capacitor 8
2 by the low-pass filter is composed of the cutoff frequency f _5.

When the level of the first filter switching signal is low and the level of the second filter switching signal is high, the first transistor 83 turns off and the second transistor 83 turns off.
Transistor 88 is turned on, and a filter-on mode is set. In this case, the resistor 62 and the second capacitor 8
In 7, a low-pass filter is composed of the cutoff frequency f _6.

Next, the operation of the optical disk device 1 according to the third embodiment will be described.

In the optical disc device 1, the cutoff frequency of the filter switching circuit 60a is selected according to the set rotation speed.

[0146] As shown in Table 2, if set to 1 × speed, the cutoff frequency is set to f _4, if it is set to 2 × speed, the cutoff frequency is set to f _5,
4 If set to speed, the cutoff frequency is set to f _6. That is, the cutoff frequency is set higher as the rotation speed of the optical disc 2 increases.

[0147]

[Table 2]

As described above, according to the optical disk device 1, when the optical head 3 is moved to the target track, similarly to the optical disk device 1 of the first embodiment described above.
Since the noise included in the tracking error signal is reduced or eliminated, the tracking error signal can be accurately and reliably binarized.
Can be accurately counted.
Therefore, the accuracy of the coarse seek is improved, and the access time can be shortened. In addition, the period from the start of the coarse seek to the time when the moving speed of the optical head 3 is stabilized is set to the filter-on mode, and then to the filter-off mode, so that the tracking error signal is removed by the low-pass filter. Can be prevented.

The frequency of the tracking error signal and the frequency of the noise included in the tracking error signal are higher as the rotation speed of the optical disk 2 is higher. However, in the optical disk device 1, the cutoff frequency of the filter switching circuit 60a is higher. Is set higher as the rotation speed of the optical disc 2 is higher, so that at 1 ×, 2 ×, and 4 × speeds, only noise included in the tracking error signal can be more reliably reduced or eliminated.

In the above-described embodiment, the rotation speed can be set to three stages (1 × speed, 2 × speed, 4 × speed). However, the present invention is not limited to this. 2x, 4x, 6x, 8x, 10x, 12x
It is sufficient that the rotation speed can be set at m steps (m is an integer of 2 or more) such as double speed and 32 times speed.

In the above embodiment, the number of cut-off frequencies that can be set by the filter switching circuit 60a is three (f ₄ , f ₄₎ .
₅ , f ₆ ), in the present invention, the number of cut-off frequencies that can be set in the filter switching circuit (high-frequency removing circuit) is 2
Or four or more.

For example, the cutoff frequencies at 1 × speed, 2 × speed, 4 × speed, 6 × speed, 8 × speed, 12 × speed, 12 × speed and 32 × speed are defined as f ₄ , f ₅ , f ₆ , f ₇ , respectively.
f ₈ , f ₉ , f ₁₀ and f ₁₁ (provided that f ₄ <f ₅ <
_{f 6 <f 7 <f 8} <f 9 <f 1 0 <f 11) may be.

Further, in the above-described embodiment, the rotation speed and the cutoff frequency correspond one-to-one, but the present invention is not limited to this.

For example, the cutoff frequency at 1 × speed is f ₄ , the cutoff frequency at 2 × speed is f ₅ , and the cutoff frequency at 4 ×, 6 ×, 8 ×, 10 ×, 12 × and 32 × speed is it may be used as the f _6.

In the present invention, the filter switching circuit 60
The selection of the cut-off frequency a is performed according to the degree of progress of the movement of the optical head 3 when the optical head 3 is moved to the target track (when the optical head 3 is moved in the radial direction) as in the second embodiment described above. Further, as in the above-described third embodiment, the configuration may be such that the operation is performed according to the set rotation speed.

As described above, the optical disk apparatus of the present invention has been described based on the embodiments shown in the drawings. However, the present invention is not limited to these embodiments, and the configuration of each section may be any configuration having the same function. Can be replaced with something.

For example, in the above embodiment, the binarizing circuit of the count signal generating device is constituted by a comparator. However, the present invention is not limited to this, and may be constituted by, for example, a limiter amplifying circuit. .

In the above embodiment, the filter switching circuit (high-frequency removing circuit) is constituted by using a low-pass filter. However, the present invention is not limited to this. For example, the filter switching circuit is constituted by using a band-pass filter. Is also good.

In the above embodiment, the signal corresponding to the number of tracks passed by the optical head is a tracking error signal. However, the present invention is not limited to the tracking error signal.

The optical disk device of the present invention is not limited to the above-described CD-ROM drive device, but may be, for example, a CD-R, a CD-RW, a DVD-R, a DVD-RA
Various optical disk devices for recording / reproducing a recordable / reproducible optical disk (optical disk having a pre-groove) such as M, a read-only optical disk such as a CD (compact disk), and various types for reproducing a recordable / reproducible optical disk The present invention can be applied to an optical disk device.

The optical disk device of the present invention can be applied to various optical disk devices for recording and / or reproducing a plurality of types of optical disks.

[0162]

As described above, according to the optical disk apparatus of the present invention, when the optical head is moved to the target position on the optical disk, the high-frequency noise component included in the signal corresponding to the number of tracks passed by the optical head Since (noise) is reduced or eliminated, an appropriate count signal can be generated, and thereby the number of tracks passed by the optical head can be accurately counted. For this reason, the accuracy of the coarse seek is improved, whereby the time required for moving the optical head 3 to the target track, that is, the access time (seek time) can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration (main part) of a first embodiment of an optical disk device of the present invention.

FIG. 2 is a plan view showing a first embodiment of the optical disc device of the present invention (with a casing removed).

FIG. 3 is a circuit diagram showing a configuration example of a count signal generation device in the first embodiment of the optical disc device of the present invention.

FIG. 4 is a timing chart showing a tracking error signal and a count signal in an acceleration region in the first embodiment of the optical disc device of the present invention.

FIG. 5 is a timing chart showing a tracking error signal and a count signal in a constant speed range in the first embodiment of the optical disc apparatus of the present invention.

FIG. 6 is a circuit diagram showing a configuration example of a count signal generation device in a second embodiment of the optical disc device of the present invention.

FIG. 7 is a circuit diagram showing a count signal generation circuit of a conventional optical disc device.

FIG. 8 is a timing chart showing a tracking error signal and a count signal in a conventional optical disc device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk apparatus 2 Optical disk 3 Optical head 31 Optical head main body 32 Objective lens 311 Support part 4 Actuator 5 Laser diode 6 Split photodiode 7 Thread motor 8 Rotation axis 81 Lead screw 9 Control means 11 Spindle motor 12 Rotation axis 13 Turntable 14 Deceleration Gear 141 Worm wheel 142 Pinion gear 15 Rack gear 16 Guide shaft 21 to 23 Driver 40 RF amplifier IC 51 Servo processor 52 Decoder 53 Memory 60 Count signal generation device 60a Filter switching circuit 60b Count signal generation circuit 61 Low pass filter 62, 65 Resistance 63 Capacitor 64 Transistors 66 to 68 Terminal 71 High-pass filter 72 Capacitor 73 Resistance 74 Comparator 741 Inverting input terminal 742 Non-inverting input terminal 75 to 78 Resistance 79 Terminal 82 First capacitor 83 First transistor 84, 89 Resistance 85, 86 Node 87 Second capacitor 88 Second transistor 90 Count signal generation circuit 91 High-pass filter 92 Capacitor 93 Resistance 94 Comparator 941 Inverting input terminal 942 Non-inverting input terminal 95-98 Resistance 105, 106 Node 200 pulse

Claims (11)

[Claims] 1. An optical disk device, comprising: a rotation drive mechanism for mounting and rotating an optical disk; and an optical head, wherein the optical head records and / or reproduces the optical disk via the optical head. A signal generation circuit for generating a signal corresponding to the number of tracks passed by the optical head when moving in the radial direction of the optical disc; and counting the number of tracks passed by the optical head based on a signal from the signal generation circuit. An optical disc device, comprising: a count signal generation circuit that generates a count signal for performing the operation; and a high-frequency removal circuit that removes a high-frequency component included in a signal from the signal generation circuit. 2. A filter-on mode in which a portion of the high-frequency removing circuit that removes the high-frequency component functions and a filter-off mode in which a portion of the high-frequency removing circuit that removes the high-frequency component does not function. 2. The optical disk device according to claim 1, further comprising a setting unit that performs setting. 3. The apparatus according to claim 1, wherein the setting unit sets the filter on mode or the filter off mode in accordance with a degree of movement of the optical head when the optical head is moved in a radial direction of the optical disk. The optical disk device according to claim 2, wherein: 4. The optical disc apparatus according to claim 2, wherein the setting unit is configured to set the filter on mode for a predetermined period when the optical head is moved in a radial direction of the optical disc. 5. The optical disk device according to claim 4, wherein the predetermined period is an initial period when the optical head is moved in a radial direction of the optical disk. 6. The optical disk device according to claim 4, wherein the predetermined period is a period from the start of the movement of the optical head to a time when the moving speed of the optical head is stabilized. 7. The cut-off frequency of the high-frequency removing circuit is higher than the frequency of a signal corresponding to the number of tracks passed by the optical head and lower than the frequency of a high-frequency noise component included in the signal. An optical disc device according to any one of the above. 8. The optical disc apparatus according to claim 1, wherein a cutoff frequency of said high frequency removing circuit can be set to a plurality. 9. The apparatus according to claim 1, wherein a cutoff frequency of said high frequency removing circuit is selected in accordance with a degree of movement of said optical head when said optical head is moved in a radial direction of said optical disk. 9. The optical disc device according to 8. 10. The rotation drive mechanism is configured to rotate the optical disc at a plurality of rotation speeds, and a cutoff frequency of the high-frequency removing circuit is selected according to the rotation speed. Claim 8 configured as follows:
An optical disk device according to claim 1. 11. The optical disk device according to claim 1, wherein the signal corresponding to the number of tracks passed by the optical head is a tracking error signal.