JPS58208972A - Carrier of magnetic head - Google Patents

Abstract

PURPOSE:To improve the accuracy of positioning of a magnetic head, by changing minutely a phase current of a pulse motor in the open loop system for moving minutely the magnetic head to an optimum position. CONSTITUTION:In the drive of the open loop system, the pulse motor 3 is rotated to position the magnetic head. Then, a signal from an off-track amount sensor 10 is applied to an off-track detecting circuit 11. Then, the detecting circuit 11 discriminates whether or not an off-track exists and whether it is necessary to correct the head position if the off-track exists and outputs a correcting signal via a correcting signal generating circuit 12. A phase current variable circuit 13 receiving it changes minutely the phase current of the pulse motor 3 to shift minutely the magnetic head to the optimum position. Thus, the accuracy of the head positioning is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION This relates to a magnetic head feeding device in a recording/reproducing device, and its purpose is to increase the head position of 112K during signal recording (writing) and the head position of 1j5 during playback (reading: 1j5).
This is to correct the deviation of the henodo position (r') at the time of shi.

Conventionally, there are two types of head positioning devices (positioners) used in this magnetic recording and reproducing device for the rod: one that performs positioning using a closed-loop thread, and the other that performs positioning using an open-loop thread.

The closed-loop system consists of a linear motor that can be moved freely by a servo circuit, a moving platform that supports one end of a head support spring and moves the head, etc., and the track position is set within the data recording track on the disk. is recorded in advance, and when reproducing data, the signal is detected and the side angle j circuit moves the head position to the fixed position, and the linear motor is activated so that the signal can be reproduced at the optimal position. The so-called data surface servo method uses a 81l1 quotient, and although it is slightly different from that method, a dedicated head is installed in a place other than the data track (usually using the surface of the disk) and only records position signals (servo signals). The head position is determined by reproducing this servo signal, processing it in the servo water circuit, and moving the linear motor in conjunction with the servo face method to move the gutter to the optimal position. There is a method called.

The closed-loop servo system using a Kowara linear motor is
Although it has the advantage of high head positioning accuracy, it has the disadvantage that it is expensive to implement a servo system consisting of a servo circuit, a linear motor, etc.

On the other hand, in the conventional closed-loop head positioning method, as shown in FIG. The motor drive circuit 2 supplies current to each phase of the pulse motor, switches its direction, and rotates the pulse motor by a predetermined amount in a predetermined direction.

As the shaft of the pulse motor rotates, the center position of the belt 4 is fixed around the shaft of the motor.
Accordingly, one end of the moving table 5 is pulled by the belt and moves to one side (disc t (0 or the opposite direction)), thereby causing the head 6 on the disk Z to
The structure was such that the position of the area also moved.

Since this method does not perform positioning by feeding back the position signal on the disk, the positioning accuracy is determined by the stopping angle accuracy of the pulse motor, which takes into account gaps in the mechanism, dimensional changes in each element and each part due to temperature changes, etc. This method has the disadvantage that the positioning accuracy is lower than that of positioning methods that use closed loop servos. However, it is widely used because it is considerably cheaper than the closed-loop method and allows for a more compact positioning mechanism.

The present invention has been made in view of the conventional drawbacks of open loops, and it is an object of the present invention to provide a magnetic head feeding device that has a simple configuration and can obtain unprecedented positioning accuracy.

Generally, in order to reproduce a signal that has been recorded on a certain trunk on a disk, it is said that it is best to place the head in exactly the same position as when recording.

To explain this relationship with a diagram, Figure 2 shows the relationship between the amount of head deviation during playback with respect to the head position during writing and the playback signal, where a is the correct playback waveform that is originally desired to be played back. b indicates a change in signal level, and b indicates a level of a noise component caused by a leakage component from an adjacent track being reproduced by a magnetic head. As shown in the figure, the playback signal level is highest when writing and playback are at the same position (this position is called on-track), and the playback head position deviates from the writing position (this is called off-track). ), the reproduced signal component a drops extremely, while the noise component increases.

For this reason, there is an off-track,
This causes a significant decrease in the reliability of the reproduced signal.

Therefore, when head positioning is performed using the υ1'' loop, it is impossible to make the trunk interval smaller than the expected positioning error, and there is a limit to increasing the recording capacity.

The present invention proposes a magnetic head feeding device that takes advantage of the closed loop feature and slightly changes the phase current of the pulse motor to correct the head position that occurs during scooping to the correct position.

A block diagram for realizing the present invention is shown in FIG.

1.2.3 in the figure is the same as in FIG.

10 is an off-trunk amount sensor, which is a data read head when the amount of decrease in the amplitude of the data signal written on the track on the disk is determined to be the off-track amount, and if it is used due to temperature change. If it is desired to correct the amount of off-track that occurs, a temperature sensor installed within the device may be used.

In addition, there is no particular restriction as long as it detects an amount correlated with off-track.

Incorporate these signals and determine whether there is an off-track or not.
If so, it passes through an off-track detection circuit 11 which determines whether it is necessary to correct the head position rli, and then a correction signal is generated by a correction signal generation circuit 12.

A pulse motor is stopped at a stable point where the magnetic field generated by the coil current flowing in the N phase of the stator (usually two phases) and the magnetic field of the rotor (rotor magnetic field) are balanced. Therefore, one of the stator phase currents is changed by a small amount As a result, the stable point changes and the stopping position changes slightly.

In general, there is a proportional relationship between the needle that unbalances the two phase currents and the stopping angle between the pulse motor's stem 211, so unbalance the phase current of the pulse motor by the amount that you want to correct the head position. It is only necessary to change one phase current by b].

This signal indicating how much to unbalance is the correction step 1.
) corresponds to the number.

The phase current variable circuit 16 is a circuit that continuously varies the current value supplied to the pulse motor, and controls the phase current by a signal from the correction signal generation circuit 12.

The system after the pulse motor is the same as that shown in FIG.

To describe a more specific embodiment of the present invention, for example, in order to optimally position the head using the data signal itself reproduced by a magnetic nod, it is necessary to use an open drive ( After positioning the head using the 1jiJ loop system drive, the head position is slightly moved by changing the phase current of the 12-pulse motor back and forth in small increments based on that position. The peak detection circuit extracts the amplitude of the signal read from the head from time to time and holds that level, and the position where the reproduced signal amplitude is largest is the correct head position at the time of ancient times. A method is used in which the head is determined to be corrected and the head is finally moved to that position.

A concrete example of this is shown in FIG.
Preamplifier 21. In addition to the conventional signal reproduction system configuration consisting of a TNX circuit 22, a disk drive controller 22', etc., a sector detection synchronization circuit 23, a track signal peak detection gate 24, a peak level maintenance circuit 1', a 'j circuit 25, a phase current versus peak level In addition, a level comparison and correction signal generation controller 27, a copying Shogakucho, etc. are added to the configuration of the head feeding system consisting of a magnetic head feeding actuator 62, a pulse motor 61, a pulse motor drive circuit 29, etc. Weird controller 28, that's it.
For commercial use (by adding circuit 60)
Realize it.

First, the magnetic head 20, which has not been moved to a predetermined position by the pulse motor, reproduces the number 4 on the disk at that position. Since the reproduced signal is small, it is amplified to a predetermined size by a preamplifier, and signal processing is performed after the demodulation circuit 22, so that the signal is shared with the host computer N times. The present invention finely adjusts this position to an even heavier optimum position.

First, we want to detect the amplitude of the reproduced signal of the preamplifier 21, but since there are various numbers written on the track, different data will have different numbers in the frequency η and different amplitudes of the Buddha name. If the amplitude (peak) was simply detected unconditionally, it would be difficult to determine whether the change in peak level was due to off-tracking or the change in amplitude due to a difference in the written data. , it is extremely unreliable as a signal that accurately captures the amount of off-track. Therefore, specifically, the following method is adopted 114. Tracks on a normal disk are divided into cheetah blocks called sectors.
The same signal is written at the beginning of one sector for a certain period of time (this is sometimes called the 5YNC signal).
. Therefore, by always detecting and using the distortion of the signal, since the frequencies are the same, it is possible to reproduce a level proportional to the amount of off-track.

From the above, the sector detection synchronization circuit 26 detects the timing signal of the sector signal, the signal at the head of the sector is taken in by the track signal peak detection gate 24, and the peak level is held by the 25°97 small angle variable controller. At 28, while slightly varying the phase current of the pulse motor, the signal at the head of the sector at that time for each phase current is captured and stored in the memory 26. Perform this operation several steps, and among them, reach the thickest peak level (・H
[ is determined at step 27, and finally a signal that should be the phase current that produces the largest reproduction amplitude is supplied from the minute angle variable controller 28 to the phase current variable circuit 30, and correction is made to move the head to that position. .

Alternatively, as another example, since it is known that one off-track is large due to the influence of temperature change,
Depending on the temperature change, the head position may change from 1") 1lill
The amount of off-track is experimentally determined in advance, and the amount of off-track is estimated at each time according to the value of a temperature sensor installed at an appropriate location, and a correction signal is generated accordingly. However, it also becomes possible to slightly correct the stop position of the pulse motor.

According to the configuration of the present invention, such as J3 or 1, it is possible to realize head positioning with considerably high accuracy without constructing a servo system with a large number of cylinders.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the configuration of a conventional open-loop magnetic head feeding device, FIG. 2 is an explanatory diagram showing the relationship between the off-trunk of a reproduction track and the reproduction signal level, and FIG.
4 are block diagrams showing the configuration of the present invention. 2... Pulse motor drive circuit, 6... Pulse motor, 10... Off-track amount sensor, 11... Off-track detection circuit, 12... Correction generation circuit, 16... Phase current variable circuit. Figure 1 Figure 2 Newsletter 40 Figure 3

Claims (1)

[Claims] In a magnetic head feeding device in a magnetic recording and reproducing device, the magnetic head feeding device includes an off-track amount sensor, an off-track detection circuit, a correction signal generation circuit, a Hulse motor control circuit, a motor drive circuit, and a motor phase current variable circuit. , rotate the pulse motor by switching the phase current, move the magnetic head to the desired position, and then change the phase current of either one of the excitation coils of the pulse motor. By making slight changes, you can increase your sex appeal 1. A magnetic head feeding device that moves the head a minute amount to the optimum position.