JP2002184134A - Disk reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a disk reproducing device to secure feeding speed during fast feed and also to perform stable fine-speed feed without being affected by the variation of individual minimum staring voltages of motors. SOLUTION: In a disk reproducing device which is provided with a slide feeding motor which feeds a slide part on which a pickup is loaded in the radial direction of a disk and which gives braking to the part by applying braking power to the part while supplying a voltage having the reverse direction of rotation to the slide feeding motor after the feeding of the slide part, an additional braking time (t) is set by detecting a pulse width from a track cross signal and by calculating the speed of the slide part from the signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk reproducing apparatus provided with a slide feed motor for moving a pickup in a radial direction of a disk when reproducing information recorded on the disk.

[0002]

2. Description of the Related Art As the above-mentioned slide feed motor, a linear motor is used in some medium- and high-end machines. However, in the slide feed by the linear motor, peripheral circuits for speed control are complicated, and the cost is increased because a high-precision slide mechanism is required. In addition, power consumption increases when a high-speed search is attempted.

[0003] Therefore, in the conventional popular type disk reproducing apparatus, most of the slide feed motor of the pickup uses a DC brush motor in combination with a rack and pinion mechanism, a ball screw and the like.

In the slide feed by a DC brush motor, as shown in FIG. 8, an input signal (Tracking Drive Signal: hereinafter) to a BTL (Balanced Transformer Less) driver 52 for driving a radial actuator coil 51 in a tracking servo loop. , T
RD signal), a low-pass component is extracted through a low-pass filter 53, and the signal is used as a slide feed motor through a slide motor driver 54.
The C brush motor 55 is driven, and the slide portion 57 on which the pickup 56 is mounted is slid.

[0005] The DC brush motor 55 as described above is
If a low output impedance BTL motor driver or the like is used, the motor coil is connected to the driver output when it is not driven due to the circuit structure, that is, it is in a low impedance state. For this reason, when the drive output from the motor driver is stopped, the brake is applied by the back electromotive force accompanying the subsequent inertial rotation.

Therefore, by the DC brush motor,
When performing a high-speed search operation by track count, as shown in FIG. First, the tracking servo is turned off at the start time (point a).

[0007] b. The rotation of the slide feed motor in a predetermined direction is started (point b).

C. A predetermined value is set in a counter for counting the track cross signal in the tracking error signal (point c).

D. When the counter reaches a predetermined value by the track cross signal, the slide feed motor is stopped (point d). → The back electromotive force brake is applied naturally.

E. Wait until the slide stops sufficiently by the back electromotive force brake of the slide feed motor and the loss torque of the slide mechanism (period indicated by e), and turn on the tracking servo (point f). Is performed in the following procedure. As described above, the DC brush motor performs a high-speed search by track count with relatively easy control.

However, in a DC brush motor, sparks are inevitable due to the presence of brush contacts in a power (current) supply path, and there is a major problem in durability. Generally, the continuous operating life of a DC brush motor is about 1,000 hours. Therefore, it is conceivable to use a three-phase brushless motor for the slide feed motor. Since such a three-phase brushless motor does not have a brush structure as compared with a DC brush motor, its durability is 5,0.
00 to 10,000 hours, 5 to 10 times that of the DC brush motor.

A motor driver for driving the above-described three-phase brushless motor has, for example, a circuit configuration as shown in FIG. That is, a switching circuit including upper-side switching transistors Tr1 to Tr3 and lower-side switching transistors Tr4 to Tr6 forming a pair is provided corresponding to the three-phase motor coils C1 to C3, respectively. A control PN is connected to each base of the upper switching transistors Tr1 to Tr3.
P transistors Tr7 to Tr9 are connected, and motor voltage supply terminals T23 and T24 are respectively connected to the emitters of the control PNP transistors Tr7 to Tr9 and the collectors of the upper switching transistors Tr1 to Tr3.
Via the motor voltage V _M.

In such a circuit configuration, each coil C
In practice such a voltage V _L to 1~C3 the voltage drop V caused by ON resistance of the upper switching transistor Tr1~Tr3 and lower switching transistors Tr4~Tr6
_CESAT only, reduced from the motor voltage V _M. Further, a diode is provided between the control PNP transistors Tr7 to Tr9 and the upper switching transistors Tr1 to Tr3 in place of the external resistor CS shown in the figure, thereby sharing the motor voltage supply terminals T23 and T24. In the motor driver described above, the voltage is further reduced by the voltage drop V _D at the diode. Therefore, V _L = V _M −2V _CESAT (−V _D ).

For this reason, even when the motor operates stably at _VL of 1 V or more, the motor voltage V _M is
At least 2.0 to 3.0 V is required. Therefore,
When the maximum value of the variable range of the motor voltage V _M Looking assuming 8V, the dynamic range of the operable voltage of the motor is a three-phase brushless motor as described above 20l
og 8/2 to 20 log 8/3 (12 dB to 8.5)
dB). This is much smaller than the above-mentioned DC brush motor of about 20 dB.

[0015]

As described above, the three-phase brushless motor has a smaller dynamic range of the operable voltage of the motor than the DC brush motor. When a motor having a number / torque characteristic is used and the gear ratio of the slide feed is the same, when the slide feed speed at the time of high-speed search or track count is increased and the search time is shortened, the following: The following problems occur.

First, as shown in FIG. 11, in the case of the motor A having a small rising time constant Zm _A , the rotation speed /
The torque characteristics are as shown in A in FIG. In the case of a three-phase brushless motor having such characteristics, the track count can be made faster, but as described above, since the operable voltage range is smaller than that of the DC brush motor, the motor voltage at the time of normal-speed slide feed during normal playback is reduced. Cannot be lowered. As a result, the acceleration of the slide feed at this time becomes large, thereby easily deviating from the margin of the servo characteristics, resulting in an unstable system.

On the other hand, in the motor having the characteristics indicated by B in FIGS. 11 and 12, since the starting torque is small and the rise time constant Zm _B is large, the high-speed search by the track count is slow. That is, as shown in FIG. 13, EFM (Eight to Fourt)
een Modulation) Due to the restriction of the upper limit frequency f _LIM determined by S / N due to noise, if the track count is to be performed until the area of the motor A becomes equal to the area (the area indicates the track count number), the time is long. And the high-speed search in the track count becomes slow.

As described above, when the three-phase brushless motor is used as the slide feed motor, the operable motor drive voltage range is narrower on the low voltage side than on the DC brush motor due to the three-phase motor drive circuit. It is impossible or difficult to achieve stable servo characteristics at the time of searching and at the time of fine-speed feeding during reproduction. Note that D
A similar problem also occurs with a C brush motor when driven at a low voltage.

In a three-phase brushless motor, DC
If a coil is short-circuited like a brush motor to generate a braking force due to a back electromotive force when the coil is stopped, a large number of external components constituting a short circuit corresponding to each coil are required.

On the other hand, in a coil short-circuit type brake using a back electromotive force, a magnetic circuit section, a motor mechanism section,
It is necessary to set the brake time in consideration of the worst conditions in consideration of variations in motor characteristics such as loss torque. For this reason, it is difficult to shorten the braking time at the time of high-speed search and track counting.

Further, in order to shorten the braking time at the time of track counting by using the reverse rotation brake, it is necessary to detect the speed of the slide portion to determine the brake release point. Since a control circuit and the like are separately required, the cost increases.

In the high-speed search by the track count, the following problem occurs in the brake area by the reverse rotation brake. In general, as shown by the solid line in the graph of FIG. 4, the point at which the slide speed changes, particularly the acceleration start point (point a)
At the brake start point (point b), the pickup vibrates at its self-resonant frequency and higher-order resonant frequency.
Therefore, no matter how the stop of the slide portion is detected, the Q of the radial actuator of the pickup can be determined.
If the acceleration at the brake start point is too large with respect to the (quality factor), or the load applied to the slide section is too small and the braking time becomes too short with respect to the torque at the time of reverse rotation braking, the vibration of the pickup will remain even after the slide section stops. In addition, the landing accuracy of the track count deteriorates.

The same applies to the above-described DC brush motor when the reverse rotation brake is used together.

High-speed search by track count
As shown in FIG. 5, a small number of tracks is targeted. At this time, a track cross signal is input to a counter for speed control / stop detection during reverse braking of the slide feed motor, and pulse width detection based on the track cross signal is performed. If so, erroneous detection due to the vibration of the pickup is likely to occur. For this reason, the timing to stop the brake is advanced, and the necessary braking time is not given,
The position where the slide portion stops stops moving forward. As a result, the landing accuracy of the track count becomes poor, or a singular point occurs.

When the track count is started (tracking servo OFF) when the pickup is not at the free center due to the eccentricity of the disk, the vibration of the pickup increases, the phase shifts, and the landing of the track count further occurs. Accuracy deteriorates.

Also, when an erroneous detection occurs due to a scratch, dirt, an external impact, or the like on the disk, the brake may be released at a much faster point.

If a reverse rotation brake is also used in the DC brush motor to shorten the braking time, the same problem as described above occurs.

In a track jump by a kick operation, when a three-phase brushless motor slides and feeds a radial actuator by a kick to compensate for the moving amount (hereinafter, this slide feed is referred to as kick assist). Depending on the state of the motor immediately before the assist of the kick, the slide feed amount by the kick assist greatly changes.

This is a three-phase brushless motor having a configuration in which there is no short circuit for short-circuiting each coil when stopped (the full-wave drive circuit of the three-phase motor driver in FIG. 10 and no short circuit is connected to the terminal T20). It occurs when you assist the kick,
In this case, since each coil becomes OPEN when the motor stops, it is necessary to consider the charging / discharging current of the coil. That is, the slide feed amount by the kick assist changes depending on the state of the motor immediately before.

In the DC brush motor as well, although it depends on the impedance of the short circuit and the impedance of the motor coil, the influence from the time immediately before the motor operation to the kick assist starts from around 10 msec or less.

[0031]

According to a first aspect of the present invention, there is provided a disk reproducing apparatus including a slide feed motor for feeding a slide section having a pickup in a radial direction of a disk. In a disk reproducing apparatus that supplies a voltage in the reverse rotation direction to the slide feed motor after the slide feed to apply a braking force to apply a brake, an acceleration start point at the time of starting the slide feed and a brake start point for switching to an applied state of the brake force. The slide feed control means for reducing the supply voltage to the slide feed motor is provided.

Therefore, in the disk reproducing apparatus according to the first aspect, by reducing the supply voltage to the motor coil at the speed change point, it is possible to minimize the acceleration acting on the pickup at this time, Vibration generated in the pickup can be suppressed. As a result, even when the slide feed is controlled by the track cross signal detected by the pickup, the detection error caused by the vibration of the pickup is suppressed, and thus more accurate slide speed control is possible.

[0033]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 2, the disk reproducing apparatus according to the present embodiment includes a slide section 2 on which a pickup 1 is mounted. The tracking error signal detected by the pickup 1 is amplified by the RF / AMP 3 and input to the servo LSI 4 as a tracking error signal TE. Phase compensation / filter AM in this servo LSI 4
Through P4a, the tracking error signal TE is converted to a tracking drive signal TRD. When this signal TRD is input to the radial actuator driver 5 along the tracking servo loop, the radial actuator coil 1a provided in the pickup 1 is energized to perform tracking servo.

On the other hand, a microcomputer (hereinafter abbreviated as “microcomputer”) 6 is provided in the slide servo loop in the above-described apparatus. The tracking drive signal TRD is further passed through a low-pass filter 4b of about 1 to 10 Hz in the servo LSI 4,
A signal indicating the average shift amount of the radial actuator coil 1a, that is, a Slide Drive signal (hereinafter, referred to as an SLD signal) for moving the slide unit 2, is sent to the A / D of the microcomputer 6 via the A / D input switch SW-1. The input is made to the D input port.

Further, the tracking drive signal TRD is passed through a low-pass filter 7 of about 300 to 500 Hz to remove high frequencies (disturbance, noise, etc.) indicating the actual position of the pickup 1 including eccentric components of the disk. This TRDFS signal becomes
The signal is also input to the A / D input port of the microcomputer 6 via the A / D input switch SW-1.

The state of the pickup 1 is grasped by the microcomputer 6 from the SLD signal and the TRDFS signal taken in through the AD input port of the microcomputer 6. From V _M control port of the microcomputer 6, the motor voltage variable circuit 8
V _M control signals for switching control is output. Further, for the three-phase motor driver 9 having the same configuration as that shown in FIG. 10 described above, an ST / SP signal for starting / stopping the start / stop of the motor, and a switching signal (Dir signal) for the rotation direction of the motor are provided. Is output from the microcomputer 6. A slide feed motor 10 composed of a three-phase brushless motor is connected to the three-phase motor driver 9, and the rotation of the motor 10 causes the slide portion 2 to be slid in the radial direction of the disk.

The microcomputer 6 is further provided with a counter input port for inputting a track cross signal based on the tracking error signal TE. The microcomputer 6 stores the SLD signal and the TRD signal.
Based on the FS signal and the track cross signal, software functioning as low-speed feed switching control means, braking control means, slide feed control means, and intermittent feed control means is incorporated. Although not shown, a memory serving as guard time storage means and a timer are built in.

Next, the specific control operation at the time of slide feed controlled by the microcomputer 6 will be divided into a fine feed at the time of disc reproduction, a high speed search by the track count method, and a low speed search by the kick operation. It will be described sequentially.

[0040] During the fine fast forward during control disc playback during fine fast forward during disc reproduction, in said V _M control signals, switches the motor voltage variable circuit 8 to the low voltage side (2-3 V), AD of the microcomputer 6 As a slide drive (SLD) signal is input to the input control port,
The A / D input switch SW-1 is switched to take in the SLD signal at regular time intervals.

Then, when the value is a predetermined value, that is, when the shift amount of the pickup 1 becomes a predetermined amount, the slide feed direction is determined based on the SLD signal and is switched by a direction switching signal (Dir signal). The start / stop control signal shown in (1) is sent to the motor driver 9 to drive the slide feed motor 10.

When a pulsed start / stop control signal is input from the microcomputer 6 to the motor driver 9 as shown in FIG. 6A, the coil of the slide feed motor 10 is applied to the coil of the slide feed motor 10 as shown in FIG. A substantially saw-tooth current flows. As can be seen from this current waveform,
The pulse width of the stop control signal is set small so as not to exceed the range of the transient response of the motor current. Thus, current product flowing through the coil is small, relatively magnetic energy in the same motor voltage V _M becomes smaller. As a result, the acceleration generated in the slide portion is suppressed.

FIG. 4C shows the change in the speed of the slide portion 2. As shown in the figure, by applying a trailing pulse, the instantaneous maximum acceleration does not need to be increased beyond the first pulse. A large slide movement amount is secured. In the figure, the area that increases with the passage of time indicates the amount of movement, and the dashed line indicates the amount of movement of only the first pulse.

Control at the time of high-speed search by the track count method The control procedure at the time of high-speed search by the track count method will be described with reference to FIG. First, in the step of "initial setting" shown in S1 in FIG. 7, the required number of track jumps to the target search destination is calculated, and the direction of the track count is set by the direction switching Dir signal of the microcomputer.

[0045] Then, the voltage V _M applied to the slide feed motor 10, the motor voltage variable circuit 8 in V _M control signals
Is set to the high voltage side (5 to 8 V) by the switching of the slide feed motor 10 by the start / stop control signal.
Is started (S2). At the same time,
The control signal between the microcomputer 6 and the servo LSI 4 sets the servo LSI 4 to the track count mode and turns off the tracking servo. Subsequently, the start / stop control signal of the microcomputer 6 is started, the slide feed motor 10 is started, and the state shifts to the track count state.

At this time, the count number calculated in S1 is set in a counter inside the microcomputer 6 to which the track cross signal is input (S3), and based on the track cross signal input in the subsequent slide feed operation. A track count is performed, and the count is sequentially decremented for each count (S4).

If it is determined in step S4 that the count value of the internal counter has reached 0, the motor voltage for starting the reverse rotation braking is changed to the slide feed motor 1
The motor voltage variable circuit 8 is switched so as to be supplied to 0, and at the same time, is switched in the reverse rotation direction by the direction switching Dir signal (S5). As a result, braking by the reverse rotation brake is started with respect to the slide feed.

At this time, the guard brake time corresponding to the track count number at this time is set in the guard timer t1 from the table of the "minimum necessary brake time for the track count number" obtained in advance by experiment. (S6), the internal counter is set to the pulse width detection mode (S7).

Next, it is determined whether the pulse width obtained from the subsequent track cross signal is larger than the predetermined pulse width A, that is, whether the speed of the slide portion has decreased to near a predetermined value (S8). Then, it is further determined whether or not the guard timer t1 has reached 0 (S9). That is, even if it is determined based on the track cross signal that the speed of the slide portion has decreased to the predetermined value, if the predetermined time has not elapsed, a result indicating that the predetermined pulse width has been detected is output. Not to be. This prevents erroneous detection of the pulse width due to, for example, vibration of the pickup, scratches, dirt, disturbance, etc. on the disk.

Thereafter, the speed of the slide unit 2 is calculated based on the point c in FIG. 4, that is, the pulse width when the predetermined pulse width is detected, and the timer t2 is calculated based on the calculation result.
Is set to the subsequent brake duration (S10).
That is, the control until the slide unit 2 stops after that is as follows:
Since the pulse width detection based on the track cross signal cannot be performed accurately due to the eccentric component of the disk, the slide unit 2
The time t from the speed to the stop is calculated by the following equation. That is, the velocity at the point b is v, the mass of the slide portion 2 is m,
The starting torque of the slide feed motor 10 consisting of a three-phase brushless motor as T, and calculates the duration t by the ^{mv 2/2 = T × t} t = mv 2 / 2T. Actually, the time t at which the slide section 2 stably stops is determined in consideration of dynamic friction of the input system and the like in T (torque) in the above equation.

When the duration t has elapsed, the supply of voltage to the slide feed motor 10 is stopped (S11, S12). In step S12, a new time is set in the timer t3 during the kick operation, which will be described later, and the details will be described later.

[0052] In the above, at the time of high-speed search of the track counting method, an example of performing switching to the high voltage side (5~8V) a motor voltage variable circuit 8 in V _M control signals in FIG. 2, below As described above, in order to reduce the vibration of the pickup 1, it is possible to adopt a control configuration in which the supply voltage during the track count operation is appropriately switched.

That is, as shown in FIG. 4, the acceleration of the slide feed motor 10 causes the vibration of the pickup 1 particularly at the acceleration start point a and the brake start point b. When the acceleration of the slide unit 2 starts when the amount of deviation of the pickup 1 from the radial free center is large, the vibration amplitude increases or the phase of the vibration changes. In addition, as shown in FIG. 5, when the braking time is short, the pulse reaches the pulse width detection point before the vibration hardly decreases. Due to the erroneous detection of the predetermined pulse width detection point c due to these vibrations, a variation in the brake area of the track count occurs, and landing accuracy deteriorates.

Therefore, as shown in FIG. 2, the signal input to the A / D input port by the AD input switching control signal before the start of track counting is converted from the SLD signal to TRDF.
The signal is switched to the S signal, that is, a signal for knowing the position of the pickup 1 at the present time, whereby the fine feed is performed near the free center, and then the track count can be started. Moreover, switching to the low voltage side in the motor voltage variable circuit 8 of the motor voltage V _M of the track counting start time, by going stepwise raising the V _M after the start of acceleration of the sliding portion 2, the vibration of the pickup 1 at the time of acceleration Can be suppressed.

[0055] In addition, or suppress acceleration at the start braking by switching the motor voltage V _M at the brake start point b in FIG. 4 to the low voltage side, in case of FIG. 5, short braking time when the track count The vibration of the pickup 1 can be reduced as much as possible by preventing the pickup 1 from becoming too much. Thereby, the predetermined pulse width detection point c in FIG. 4 indicating the decrease in the speed of the slide unit 2 is stabilized, and the landing accuracy of the track count can be improved. For example, when the disk eccentricity is 50 to 60 μm or less, the landing accuracy can be set to about ± 50 tracks.

Control at the time of low-speed search by kick operation If the drive circuit of the three-phase brushless motor does not have a function of short-circuiting the motor coil, the kick assist fine feed is performed depending on the state immediately before the motor when the kick assist fine feed is performed. The amount of movement is greatly affected.

Therefore, in this embodiment, the three-phase motor driver 9 is controlled by the start / stop signal and the direction switching signal Dir from the microcomputer 6 shown in FIG. Perform assist.

The control procedure at that time will be described with reference to FIG. First, in "initial setting" of step S21, the number of kicks is calculated, and the calculation result and the direction of the kick are set. Next, the necessary assist amount corresponding to the number of kicks is read from a table stored in advance (S22). In this table, the relationship between “drive pulse width and motor rotation angle” as shown in FIG. 7 is previously obtained by an experiment, and an assist amount table is created from this. From this table, assist pulses corresponding to the number of kicks are set.

Next, in step S23 of FIG.
It is determined whether or not the kick assist control timer t3 has become 0. This timer t3 is set in step S3 described later.
The value set at 0, that is, the value set at the end of the previous kick assist. Therefore, after the end of the previous kick assist, the set time of the timer t3 elapses, and if the timer t3 is 0, the process proceeds to the step S
25, and if the set time has not elapsed, the pulse width of the assist pulse set based on the assist amount table is corrected in S24 according to the remaining time at this time. Move to step S25.

The above-mentioned correction corresponds to the presence or absence of accumulation of the residual current energy after the stop of the current supply to the motor coil. That is, as described above, a three-phase brushless motor is used as a slide feed motor. At this time, the three-phase full-wave drive circuit does not have a circuit for short-circuiting the motor coil when the motor is stopped. When the time from the operation to the assist of the kick is short and there is an effect of the residual energy in the coil, the slide feed amount by the assist of the kick is greatly changed.

[0061] Therefore, keep in store the state immediately before the motor, accumulated in the motor coil were E = LI ^2/2
(L: inductance of the motor, I: current flowing to the motor) energy is obtained, and the pulse width of the assist pulse is corrected. Thus, even when the elapsed time from the previous motor operation is short and the residual energy of the motor coil is not sufficiently self-discharged, stable kick assist can be performed in consideration of the energy storage amount.

After the correction according to the elapsed time at the timer t3 is performed, the kick operation is started (S2).
5). And almost at the same time kick assist starts,
The output of the above assist pulse is started (S26).
Thereafter, when the timer t4 detects that a predetermined time has elapsed (S27), the kick assist operation is completed (S28), and the slide feed motor 10 is stopped.

Thereafter, the length of the kick assist operation period is determined (S29). If the period is longer than a predetermined time, an initial value corresponding to the time is set in the kick assist control timer t3 (S30). . Next, the completion of the kick operation in the tracking servo system is waited (S31).
Thereafter, kick end processing is performed (S32), and the kick operation control at this time is ended.

If the previous motor operation was a high-speed search based on the track count, an initial value is set in the kick assist control timer t3 in step S12 in FIG.

As described above, in the above embodiment, a highly durable three-phase brushless motor is used as the slide feed motor 10, and the slide feed servo circuit having the above-described control functions is provided. A disk playback device is configured.

Particularly, when a three-phase brushless motor is conventionally used as a slide feed motor, the operable motor drive voltage range is limited on the low voltage side by a motor drive circuit, as compared with a DC brush motor.
For this reason, there is a problem that it is impossible or difficult to achieve both a high-speed search and a margin of servo characteristics at the time of fine-speed feeding during reproduction.

On the other hand, in the above embodiment, the pulse width control drive by software is performed for the slide feed at the time of the fine speed feed, so that the acceleration applied to the slide portion 2 can be suppressed to a low level even at a relatively high motor voltage. I can do it.

That is, driving of the three-phase brushless motor
The possible voltage range is relatively widened by the above control.
It will be. Also, be sure to supply the motor
Pressure V _MThen, drive with pulse wave as above,
Also, a radial actuator with A / D input of microcomputer
To detect and control the shift amount of 1a
Stable without being affected by variations in the minimum start-up voltage
Slow feed near the free center of the radial actuator
I can do it.

As a result, it is possible to provide a disk reproducing apparatus having a more durable and highly reliable high-speed search, and capable of stably performing fine-speed feeding. If the above control is applied to a slide feed servo with a DC brush motor, a higher speed search by increasing the feed gear ratio and a disk reproducing device capable of high speed search while lowering the motor voltage will be realized. Becomes possible.

In the above-described embodiment, in the high-speed search by the track count, after the track count area (the area from the point a to the point b in FIG. 4) ends, the control of the brake area for applying the reverse rotation brake by the three-phase brushless motor is performed. Then, the track cross signal is applied to the counter input of the microcomputer 4, the pulse width of the track cross signal is detected, and when it is detected that the slide feed speed has decreased to a predetermined value, thereafter, the slide feed speed at that time is calculated. T = mv ² / so that the slide section 2 completely stops.
2T (m: mass of slide part, T: motor torque, v:
The brake is controlled so as to be continued for a time t determined by the speed of the slide portion).

In this case, only the counter port of the microcomputer 6, an output port for turning on / off the slide motor and an output port for controlling the forward / reverse rotation of the slide motor are used, and a peripheral mechanism / circuit for control, for example, FG It does not require detection, FV conversion, etc., and can control the reverse brake speed relatively stably with minimum cost. Moreover,
The braking area time can be shortened compared to the conventional braking by the reverse starting force in the case of a motor coil short, and a higher speed search can be performed.

Also, in the above embodiment, when the subsequent braking time is controlled by detecting a predetermined pulse width in the braking area by the reverse rotation brake of the three-phase motor at the time of the high-speed search by the track counting, A table of a minimum necessary brake time correlated with the acceleration time or the designated track count is stored in advance. Then, even if the above-mentioned predetermined pulse width is detected within the table value of the brake time, that is, within the required brake time, the processing does not shift to the brake release processing.

This prevents the brake from being released based on the vibration of the pickup in the speed control at the time of braking and the erroneous detection of the pulse width due to scratches, dirt, disturbance of the disk, etc., and prevents shortage of the brake. You. As a result, the landing accuracy of the track count is improved, fail-safe is achieved, and a series of operations during seek, that is,
When shifting from the count to the next kick, the number of kicks can be reduced, and the average seek time can be reduced.

Further, in the above embodiment, the motor voltage at the speed change point in the track count area (motor acceleration area) and the reverse rotation braking area is reduced in order to suppress the vibration of the pickup in the high speed search by the track count. Control.

That is, in a high-speed search of a track count system using a three-phase brushless motor as a feed motor, when a decrease in the speed of the slide portion is detected based on the pulse width of the track cross signal, the track count area and the brake area are not detected. The speed change point of the slide unit 2, that is, the speed difference between the pickup 1 and the slide unit 2 due to the vibration of the pickup 1 when acceleration occurs, poses a problem. In other words, although the symmetry of the speed control is the slide portion 2, since the track cross signal obtained from the pickup 1 is used for the speed detection signal, accurate vibration control cannot be performed if the vibration of the pickup 1 is large. .

[0076] Therefore, as described above, to reduce the motor voltage V _M at a rate change point of the sliding portion 2, by going continuously or stepwise switching, out to suppress the acceleration of the pickup 1. At the start of the track count, a signal corresponding to the radial displacement of the pickup 1 is passed through the low-pass filter 7 to the A
/ D input port, whereby the shift amount of the pickup 1 is known, so that a phenomenon in which the vibration of the pickup 1 increases when the shift amount of the pickup 1 is large at the start of the track count can be suppressed, and almost accurate slide speed control can be performed. Becomes possible. In particular, by performing control so that the track count (motor acceleration) starts near the free center of the pickup 1 in the radial direction, a high-speed search by the track count method having more stable landing accuracy can be performed.

In the high-speed search of the track count system using the DC brush motor as the slide feed motor, erroneous counting of the track count is prevented by preventing the vibration of the pickup by the above-described control. Also, when the predetermined pulse width is detected in the reverse rotation braking region, more stable brake control can be performed by using the above control together.

On the other hand, in the above-described embodiment, in the assist feed during the kick operation, the correction according to the immediately preceding motor non-operation time is performed on the motor supply voltage. That is, when assisting the kick, that is, when the slide unit 2 is moved by the shift of the pickup 1 when executing the track jump in the shift of the pickup 1, the state of the motor immediately before is stored in software and stored in the coil of the motor. It was corrected by performing corresponding to E = 1 / 2LI ^2, performs the kick assists.

Thus, it is possible to more reliably perform the assist amount corresponding to the number of kicks. As a result, stable and reliable kick assist can be achieved even if a general-purpose low-priced three-phase motor driver without a short brake circuit is used, and a continuous kick operation can be performed. It is possible to configure as a fast disk reproducing device.

When the impedance of the short circuit system cannot be reduced too much even with a DC brush motor,
With the same control as described above, stable assist can be performed. As described above, in the above-described embodiment, the example in which the slide feed motor is configured by the three-phase brushless motor has been described. However, the present invention can be applied to an apparatus in which the slide feed motor is configured by the DC brush motor. It is.

[0081]

As described above, the disc reproducing apparatus according to the first aspect of the present invention includes the slide feed motor that feeds the slide portion on which the pickup is mounted in the radial direction of the disc. In a disk playback device that applies a braking force by applying a voltage in the reverse rotation direction to apply braking force, supply to the slide feed motor at the acceleration start point when starting slide feed and the brake start point when switching to the state of application of brake force This is a configuration in which slide feed control means for reducing the voltage is provided.

Thus, the acceleration acting on the pickup at the speed change point can be suppressed as much as possible, and the vibration of the pickup can be suppressed. For this reason, even when the slide feed is controlled by the track cross signal detected by the pickup, a detection error due to the vibration shift amount of the pickup is suppressed, and as a result, more accurate slide speed control becomes possible. .

[Brief description of the drawings]

FIG. 1 is a time chart showing a correspondence relationship between a start / stop signal at the time of a very low speed feed, a current flowing through a motor coil, an angular velocity of a motor, and a speed of a slide unit in a disk reproducing apparatus according to an embodiment of the present invention. is there.

FIG. 2 is a control block diagram illustrating a main configuration of the disc reproducing apparatus.

FIG. 3 is a flowchart showing a control procedure at the time of a high-speed search by a track count method in the disc reproducing apparatus.

FIG. 4 is a graph for explaining changes in a feed speed of a slide unit, a speed of a pickup unit, and a track count frequency during a high-speed search by a track count method.

FIG. 5 is a graph for explaining a change in a feed speed of a slide unit and a change in a speed of a pickup unit when a short track is counted.

FIG. 6 is a flowchart showing a control procedure at the time of a low-speed search by a kick operation in the disc reproducing apparatus.

FIG. 7 is a graph showing a relationship between a motor rotation angle and a drive pulse width which is a reference when creating a table of a motor supply voltage set during a low speed search by the kick operation.

FIG. 8 is a control block diagram showing a main part configuration in a conventional disk reproducing apparatus.

FIG. 9 is a time chart showing an operation at the time of a high-speed search by a conventional track count.

FIG. 10 is a circuit diagram illustrating an example of a configuration of a motor driver that drives a three-phase brushless motor.

FIG. 11 is a graph for explaining starting characteristics in a three-phase brushless motor.

FIG. 12 is a graph for explaining a torque-rotational speed characteristic in a three-phase brushless motor.

FIG. 13 is a graph for explaining a relationship between a track count frequency in a track count method and a lapse of time until the end of counting.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Pickup 2 Slide part 6 Microcomputer (braking control means, slide feed control means, guard time storage means) 10 Slide feed motor

Claims (1)

[Claims] 1. A slide feed motor for feeding a slide section on which a pickup is mounted in a radial direction of a disk,
In a disk reproducing apparatus that supplies a voltage in the reverse rotation direction to the slide feed motor after the slide feed to apply a braking force to apply a brake, an acceleration start point when starting the slide feed and a brake start point for switching to a state in which the brake force is applied. And a slide feed control means for reducing a supply voltage to the slide feed motor.