JPH0449529A - Seek control method for information storage device - Google Patents

Abstract

PURPOSE:To position a light beam spot on an objective track in the shortest time after reception of a seek instruction by sending a track-on instruction after the waiting time for shortest-time tracking-on completion corresponding to the extent of movement of a carriage. CONSTITUTION:When receiving the seek instruction, a control means 11 calculates the extent of movement of a carriage 4 in accordance with a given objective track and the present position of a head 2 and determines the extent of driving of a driving source 10 in accordance with this extent of movement to rotate a coupled pulley 5 and moves the carriage 4 through a steel belt 6 and sends a track-on instruction to a tracking servo circuit 13 to control the actuator of the head 2 after stopping the driving source 10, and thus, the light beam spot projected from an objective lens is positioned on the objective track of an information recording medium. The preliminarily experimentally obtained period from the stop time of the driving source 10 to the sending time of the track-on instruction is stored in a storage means 12 corresponding to the extent of movement of the carriage 4. Consequently, the control means 11 sends the track-on instruction when the time obtained from the storage means 12 elapses after stop of the driving source 10.

Description

[Detailed Description of the Invention] [Table of Contents] Overview Industrial Field of Application Conventional Technology Problems to be Solved by the Invention Means for Solving the Problems Action Examples Effects of the Invention [Summary] After receiving a seek command, Regarding the seek control method for information storage devices that minimizes the time to completion of head positioning, the aim is to minimize the time from motor stop to completion of tracking, and the carriage with the head mounted is moved by a drive source. When the drive source is stopped in accordance with the amount of movement of the carriage in an information storage device that positions the head on a target track by sending a track-on command after the carriage is moved and the drive source is stopped. A storage means is provided for storing the time from when the carriage is moved until the track-on command is sent, and the storage means is referred to based on the amount of movement of the carriage, and the time point when the time elapses from the time when the drive source is stopped. Then, the track-on command is sent.

[Industrial application field]

The present invention relates to an information storage device that controls a carriage on which a head is mounted and positions the head on a target track to record/reproduce information, and in particular, the head positioning is performed from the time a seek command is received until the positioning of the head is completed. The present invention relates to a seek control method for an information storage device that minimizes the time required.

Magnetic disk devices are used as external storage devices for computer systems, but in response to the demand for larger capacity external storage devices, optical disk devices with even larger storage capacities are being provided.

However, since optical disk devices use optical heads with a large mass, compared to magnetic disk devices, the movement of the carriage ends after receiving a seek command, and tracking (an actuator moves the optical disk to a designated track). The disadvantage is that it takes a long time to complete the operation of positioning the light beam spot (positioning the light beam spot), that is, the access time is long.

By the way, a carriage equipped with an actuator that moves the objective lens to position the light beam spot on the target track can be moved by motor drive if the light beam spot cannot be positioned on the designated track by actuator operation alone. However, it is necessary that tracking is turned on (the positioning of the light beam spot is completed) as quickly as possible after the motor drive stops.

[Conventional technology]

FIG. 5 is a diagram illustrating an example of an optical disk device.

The apparatus includes a plurality of optical disks I rotated at a constant speed by a spindle motor, and heads 2 are provided on both sides of the optical disk 1. Then, the head 2 is moved in the direction of arrow A by the slider 3 to select one of the optical discs 1,
Further, it is mounted on the carriage 4 located below the head 2, and can be moved in the radial direction of the optical disc 2 as indicated by arrow B by driving the boot I75 with a motor.

FIG. 6 is a diagram illustrating an example of the carriage.

FIG. 6 shows the carriage 4 used in the optical disk device shown in FIG.
) is a plan view, and FIG. 6(c) is a side view.

In FIG. 6, the carriage 4 is an L-shaped member,
Steel belt 6 with one end fixed on the right side with screw 8
is wound around a pulley 5 connected to the output shaft of the motor, and then the other end of the steel heald 6 is fixed to the left end side of the carriage 4 via a leaf spring 7 with a screw 9.

This steel belt 6 is fixed via a leaf spring 7 by applying a predetermined tension to the steel belt 6 and pulling the pulley 5.
This is to prevent the steel belt 6 from bending as it rotates.

Therefore, by rotating the boo IJ 5 with the motor, the carriage 4 can be moved linearly in the pulley rotation direction.

However, when such a steel belt 6 is fixed with a leaf spring 7, the carriage 4 is rotated by the rotation of the boot U5.
When moving the carriage 4, an inertial load is applied to the plate spring 7 when the carriage 4 starts and stops, so even if the pulley 5 stops, the carriage 4 vibrates due to the restoring force of the plate spring 7, and residual vibration continues. I will do it.

If the vibration of the carriage 4 is large, it is difficult for the actuator of the head 2 mounted on the carriage 4 to move the objective lens and position the beam spot on the specified track, and retries are repeated, resulting in tracking-on. It will take longer to get there.

However, if the vibration of the carriage 4 is small, tracking-on is possible, but the magnitude and duration of the residual vibration of the carriage 4 vary depending on the amount of movement of the carriage 4.

FIG. 7 is a diagram illustrating an example of the amount of movement of the carriage and the duration of vibration.

FIG. 7 shows the amplitude and residual vibration duration of the carriage 4 after the pulley 5 shown in FIG. 6 is driven by a step motor and the step motor is stopped.

That is, ■ is the case when the step motor is driven by 1 step, ■ is when the step motor is driven by 5 steps, ■ is 10 steps, ■ is 20 steps, ■ is 30 steps, and ■ is 5 steps.
0 step, ■ indicates 60 steps, ■ indicates 1 (10 steps), ■ indicates 5 (10 steps), and [phase] indicates the case of driving 1 (100 steps).

In this way, there are differences in the magnitude and duration of vibration depending on the number of drives of the step motor, and the amplitude is large and the duration of vibration is long at steps 5 to 20, indicated by ■ to ■, and around 60 steps, indicated by ■. ,■,■,■,[Phase] As shown in [phase], there are cases where the number of steps is small, around 60 steps, and 1 (1
At 0 steps or more, the amplitude is small and the vibration duration is short.

[Problem to be solved by the invention]

FIG. 8 is a diagram illustrating the time from stopping the step motor to completing tracking.

If we take the vibration waiting time on the horizontal axis and the tracking-on completion time on the vertical axis, we can see that as shown in the curve ■, as the vibration waiting time becomes longer, the amplitude of the carriage decreases over time, and the track-on command is sent out. The time from when tracking is completed to when tracking is completed is shortened.

However, when the amplitude of the carriage becomes less than a predetermined value, the actuator can follow the track, so when the amplitude reaches a level that does not result in repeated retries, when a track-on command is sent, as shown by the curve @, The vibration waiting time period where the sum of the vibration waiting time on the horizontal axis and the tracking-on completion time shown in curve 0 is the minimum, that is, the time from when the step motor stops until the tracking-on is completed is the shortest, as shown in [phase]. There are time zones.

If you wait for vibration beyond this time period, the time it takes to complete tracking will become longer.

Therefore, it is necessary to send the track-on command within the time period shown in ■ during the vibration waiting time.
As explained in Fig. 7 (as explained in Fig. 7), the amplitude and duration of vibration of the carriage vary depending on the amount of movement of the carriage, that is, the amount of drive of the step motor. There is also a problem in that the transmission timing also fluctuates.

In view of these problems, the present invention determines the optimal timing for sending a track-on command according to the amount of movement of the carriage, thereby reducing the time from when the step motor stops until tracking-on is completed. The aim is to be as short as possible.

[Means to solve the problem]

FIG. 1 is a block diagram illustrating the invention in detail.

When the control means 11 of the information storage device as shown in FIG. 5 receives a seek command sent from a host device, it calculates the amount of movement of the carriage 4 from the given target track and the current position of the head 2.

Then, the drive amount of the drive source 10 is determined from this movement amount, the drive source 10 is driven, and the pulley 5 coupled to the drive source 10 is
By rotating the drive source 10, the carriage 4 carrying the head 2 is moved via the steel belt 6.
After stopping, a track-on command is sent to the tracking servo circuit 13 to control the actuator of the head 2 to position the light beam spot projected by the objective lens on the target track of the information recording medium.

The control means 11 drives the drive source 10 and refers to the storage means 12 based on the calculated movement amount of the carriage 4.

The storage means 12 stores the time from the time when the drive source 10 is stopped until the time when the track-on command is sent, which has been previously obtained through experiments, in correspondence with the amount of movement of the carriage 4.

Therefore, when the time obtained from the storage means 12 has elapsed since the drive source 10 was stopped, the control means 11 performs the following operations.
As described above (send track-on command).

[Effect]

By configuring as described above, the control means 11 can send out the track-on command at the optimum timing stored in the storage means 12, so it takes a long time from stopping the drive source 10 to completing the tracking-on. It can always be kept as short as possible.

〔Example〕

FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention.
FIG. 3 is a diagram illustrating the operation of FIG. 2.

In FIG. 2(a), when the processor 15 receives a seek command from the host device, it moves the carriage 4 from the target track position given at the time of receiving the seek command and the current position of the head 2 obtained from the tracking servo circuit 13. The amount of movement is calculated, and the number of steps to be supplied to the step motor 18 is calculated from the calculated amount of movement, and the A-phase drive circuit to E-phase drive circuit 14A as shown in FIG. 2(b) is calculated.
14E respectively.

That is, the processor 15 outputs the control signals Lal, La2 and P
a, the A-phase drive circuit 14A is controlled by control signals Lbl, L
B-phase drive circuit 14B is controlled by b2 and Pb, C-phase drive circuit 14C is controlled by control signals Lcl, Lc2 and Pc, and control signal Ldl.

Ld2 and Pd drive the D-phase drive circuit 14D, and control signals Lel, Le2 and Pe drive the E-phase drive circuit 14B.
are driven respectively.

Further, the reference voltage (8) is supplied to the A-phase drive circuit to E-phase drive circuit 14A to 14E through a voltage switching circuit including a transistor 17 and resistors R1, R2, and R3, respectively. When the transistor 17 is off, the power supply voltage +5■ is supplied as the reference voltage (2), but when the transistor 17 is on, the reference voltage (2) reduced to the divided voltage of the resistors R1 and R2 is supplied.

The step motor 18 is a 5-phase motor with excitation phases of A phase, B phase, C phase, D phase, and E phase, and a resolution of 0.45 degrees per step rotation is obtained by 4-5 phase excitation.

As described in FIG. 6, a boolean U5 is attached to the rotating shaft of the step motor 18, and a steel belt 6 is wound around the boolean U5. Therefore, as the pulley 5 rotates, the carriage 4 moves linearly to transport the head 2.

In the memory 16, the time from the time when the step motor 18 is stopped until the track-on command is sent out is stored as a table, which has been obtained through experiments in advance, corresponding to the amount of movement of the carriage 4.

FIG. 3(a) shows actual measurement data of the vibration waiting time and tracking-on completion time when the residual vibration of the carriage 4 is small, as shown in ■, ■, ■, and [phase] in FIG. Figure [Exist]) shows actually measured data of vibration waiting time and tracking-on completion time when the residual vibration of the carriage 4 is large, as shown in ■, ■, ■, etc.

As in Figure 8, the vertical axis on the left shows the tracking-on completion time (in ms), and the horizontal axis shows the vibration waiting time (in m).
s) and plot the total time on the vertical axis on the right (unit: ll5)
As explained in FIG. 8, the curve {circle around (2)} shows that the longer the vibration waiting time, the shorter the tracking-on completion time.

However, as shown by the curve @, the total time of the vibration waiting time and the tracking-on completion time increases as the vibration waiting time becomes longer.

The curve @ in Figure 3(a) is when the vibration waiting time is 20m5.
This shows that tracking-on is completed in the shortest total time of 60 m5, and the sending timing of the track-on command obtained from the curve @ is the step motor 1.
It is best to do this 20m5 after stopping 8.

Also, the curve @ in Figure 3(b) has a vibration waiting time of 601TI.
When S, the total time is 861Ls, which indicates that the tracking-on is completed in the shortest time, and the sending timing of the track-on command obtained from the curve @ is 60 steps after the step motor 18 is stopped. is optimal.

The table in the memory 16 is based on the above-mentioned actual measurement data, and the sending timing of the track-on command is stored as a table for each of a plurality of groups in correspondence with the amount of movement of the carriage 4.

As described above, the processor 15 drives the A-phase drive circuit to E-phase drive circuits 14A to 14E, and also refers to the table in the memory 16 based on the amount of movement of the carriage 4 to search for the time specified by the table.

The processor 15 has an A-phase drive circuit to an E-phase drive circuit 14A to
After driving the step motor 18 by the number of steps calculated as described above through step 14E, the step motor 18
When the time indexed from the table has elapsed from this time, a track-on command is sent to the tracking servo circuit 13 specifying the track on which the light beam spot is to be positioned.

When the tracking servo circuit 13 receives the track-on command, it controls the actuator of the head 2 to move the objective lens and position the light beam spot on the designated track.

FIG. 2(b) is a detailed block diagram of the A-phase drive circuit 14A of FIG. 2(a). In addition, the B-E phase drive circuits 14B to 1
The same applies to 4E.

Reference numeral 44 denotes an output circuit section, which controls the current to the A-phase coil 46 of the step motor 18. 48 is a logic input section, into which the phase signal Pa and current control signals Lal and La2 from the processor 15 are input. 50 is a current detection unit, which receives current control signals La1. from the processor 18;
A current control signal is output according to La2. A pulse generator 52 outputs a pulse signal whose on-duty is controlled according to the current detection signal from the current detector 50 to the output circuit 44.

The output circuit section 44 includes four transistors TRI.

TR2, TR3, and TR4 are provided by H-type bridge connection and constitute an excitation circuit for the A-phase coil 46. Diodes D1 to D4 for suppressing spikes are connected in parallel to each of the transistors TRI to TR4, and the transistors TRI to TR4 are connected in parallel to each other.
, TR2 are provided with NOT circuits 19 and 20 at their bases, and three-man NOR circuits N1 and N2 are provided at the bases of transistors TR3 and TR4. Further, a driving voltage m is supplied to the collector sides of the transistors TRI and TR2, and the emitters of the transistors TR3 and TR4 are commonly connected to a current detection resistor rd.

The logic input section 48 includes a Schmitt trigger circuit S for removing noise from the phase signal Pa from the processor 15.
T, a delay circuit DL that prevents a short-circuit state when switching the phase of the transistors TRI to TR4 of the output circuit section 44, and inverts the output of the delay circuit DL and outputs it to the NOT circuit 19 and the NOR circuit N2 of the output circuit section 44; A NOT circuit 21 is provided.

Further, the other output of the delay circuit DL is directly connected to the NOT circuit 20 and the NOR circuit N1 of the output circuit section 44.

The logic input section 48 receives a current control signal La1゜La2
The four AND circuits -1 to A4 that input the above are digitized.

AND circuit AI outputs high current level signal H3, and AN
D circuit A2 outputs a medium current level signal MS, AND circuit A3 outputs a low current level signal LS, and AND circuit A
4 outputs a zero current level signal ZS. These four ANs
Outputs corresponding to the current levels of the current control signals Lal and La2 from the processor 15 for the D circuit circuits -1 to A4 are as shown in the table below.

The current detection unit 50 is provided with three comparators 01-C3, and the ten input terminals of the comparators 01-C3 are connected in series with resistors rl, r2. r3. Reference voltage Vrl, Vr2 .r4 as a divided voltage of r4. vr3 is input respectively.

Comparator C1 receives high current level signal H3 from AND circuit AI.
It becomes operational only when is output.

Further, the comparator C2 is activated only when the medium current level signal MS is output from the AND circuit A2.

Furthermore, the comparator C3 is activated only when the low current level signal LS is output from the AND circuit A3. A detection voltage Vs of a current detection resistor rd provided in the output circuit section 44 is input to one input terminal of the comparators 01 to C3. Therefore, when the voltage Vs detected by the current detection resistor rd exceeds the reference voltages Vrl to Vr3 in any one of the operating states based on the AND circuit circuits -1 to A3, the comparators 01 to C3 output the monostable voltage of the pulse generator 52. Outputs a trigger pulse to multivibrator MMB.

When the monostable multivibrator MMB provided in the pulse generation circuit 52 receives a trigger pulse from any of the comparators 01 to C3, it produces a pulse output for a certain period of time determined by its time constant. Transistors TR3 and TR4 are turned on via NOR circuits Nl and N2.

That is, by controlling the on-duty of the transistors TR3 and TR4 by pulse drive from the monostable multivibrator MMB using a trigger pulse from one of the comparators C1 to C5, the drive current flowing to the A-phase coil 46 due to its function as a switching regulator is controlled. control and constant current control.

FIG. 4 is a flowchart explaining the operation of FIG. 2.

The processor 15 monitors the reception of the seek command in step 0, and upon receiving the seek command, calculates the number of steps from the amount of movement to the target track in step (2). Then, the step motor 18 is driven in step [phase].

When the step motor 18 starts to be driven, the processor 15 moves to step (2), divides the number of steps into groups, and in step [phase] indexes the waiting time corresponding to each group from the table in the memory 16.

Then, when the waiting time is determined in step [phase], the end of driving of the step motor 18 is waited for in step [stock], and when the driving of the step motor 18 is finished, the time determined in step [phase] is set in the internal timer in step ■. Configure and start. Then, in step @, it waits to receive a signal from the timer, and when the internal timer notifies that the set time has elapsed, it sends a track-on command to the tracking servo circuit 13 in step 0.

〔Effect of the invention〕

As explained above, the present invention makes it possible to send a track-on command with a wait time that allows tracking-on to be completed in the shortest time in accordance with the amount of movement of the carriage. The beam spot can be positioned on the target track.

[Brief explanation of drawings]

FIG. 1 is a block diagram explaining the present invention in detail, FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention, FIG. 3 is a diagram explaining the operation of FIG. 2, and FIG. 4 is a block diagram explaining the operation of FIG. Flowchart explaining the operation in Figure 2, No. 5
Figure 6 is a diagram explaining an example of an optical disk device, Figure 6 is a diagram explaining an example of a carriage, Figure 7 is a diagram explaining an example of the carriage movement amount and vibration duration time, and Figure 8 is a diagram explaining the step motor stopped. FIG. 3 is a diagram illustrating the time from when the tracking is turned on until the completion of tracking. In the figure, ■ is an optical disk, 2 is a head, 3 is a slider, 4 is a carriage, 5 is a pulley,
6 is a steel belt, 7 is a leaf spring, 8, 9
10 is a screw, 10 is a drive source, 11 is a control means, 12 is a storage means, 13 is a tracking servo circuit, 14 is a drive circuit, 15 is a processor, 16 is a memory, 17 is a transistor, and 18 is a step motor. (7) Pesce 7) Selectively speak → - +1he Contains S 8 Copy 8892 -L-L-L-Fat Public Stop Ha Calm 7-Cooking-type Second Country's Complaint Fig. 8 shows the flowchart to explain the time it takes for the step motor to stop, stop, and complete turning on.

Claims (1)

[Claims] The carriage (4) on which the head (2) is mounted is driven by a drive source (1).
0), and after stopping the drive source (10), sends out a track-on command to position the head (2) on a target track. Correspondingly, the drive source (1
A storage means (12) is provided for storing the time from when the carriage (4) is stopped to when the track-on command is sent, and the storage means (12) stores the time from when the carriage (4) is stopped to when the track-on command is sent.
), the track-on command is sent out when the time elapses from when the drive source (10) is stopped.