JP2512162B2 - Positioning device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention positions a magnetic head in a magnetic recording / reproducing apparatus in which the magnetic head is moved onto a desired track of a medium such as a magnetic disk to perform magnetic recording or reading. The present invention relates to a positioning device for doing.

2. Description of the Related Art FIG. 2 is a schematic block diagram showing a conventional positioning device. In FIG. 2, 1 is a medium such as a magnetic disk, 2 is a servo signal detecting means for detecting a servo signal from a read signal of the medium 1, and 3 is a servo signal detecting means 2.
An analog / digital (A / D) converter for converting a servo signal from an analog signal to a digital signal, 4 is a microcomputer (hereinafter, referred to as a microcomputer) as a calculation means, and an output signal of the A / D converter 3 The offset amount and its correction amount are calculated from the table, and the command value for speed control during seek is stored as a table with the difference between the number of tracks to be sought (the number of remaining tracks to be sought). 5 is a digital / analog (D / A) converter that converts the digital offset correction amount and speed control command value from the microcomputer 4 into an analog signal, and 6 is the output signal and position signal feedback value of the D / A converter 5. A motor control / driving circuit for converting the motor current value based on this to control the positioning motor, 7 is a positioning motor that is controlled and driven by the motor control / driving circuit 6, and moves the magnetic head to a desired track, 8 is positioning It is an encoder (optical / phase encoder) that detects the position signal of the motor 7.

The operation of the conventional positioning device will be described below with reference to the waveform diagram of FIG. 3 for explaining the operation.

First, in the speed control (seek) mode, the encoder 8 obtains a position signal corresponding to the rotation of the positioning motor 7. Based on this position signal, the microcomputer 4
The number of tracks moved is counted, and the speed command value is output according to the stored speed profile table. This speed command value is converted into an analog signal by the D / A converter 5 and applied to the motor control / drive circuit 6. The motor control / drive circuit 6 converts the output signal of the D / A converter 5 into a motor current value, and thereby the positioning motor 7
Control the speed.

When the magnetic head moved by the positioning motor 7 moves to the vicinity of the target track (about 1/4 track before), the microcomputer 4 switches the motor control / drive circuit 6 to enter the settling mode. The purpose of this mode is to converge the residual vibration, and the motor control / drive circuit 6
By increasing the phase margin without increasing the gain of the system, the damping of the system is greatly actuated, and the residual vibration is stably damped.

After that, the microcomputer 4 switches the motor control / drive circuit 6 to enter the position control (following) mode. In this mode, the low-frequency gain of the motor control / drive circuit 6 is increased, and the stiffness against disturbance is increased. The servo signal detecting means 2 detects a position error with respect to the servo signal written on the medium 1, and the positioning motor 7 performs a following operation. At this time, in the motor control / drive circuit 6, when the motor current corresponding to the control input is as shown in FIG. 4, the motor current flows even though there is no input and it is not necessary to move the positioning motor 7. As a result, a malfunction may occur, or the motor current may cause noise, which may cause a failure in read / write operation. Therefore, as shown in FIG. 5, a dead zone p is usually provided in the vicinity of the input 0 so that no current flows through the positioning motor 7 for the input in this range.

However, in the above-described conventional configuration, unless the settling mode is entered at the optimum plunge speed, the motor current is not optimally controlled and the residual vibration becomes long or oscillates. There is an inconvenience of causing an unstable phenomenon. This is because the offset voltage adjustment in the motor control / driving circuit 6 is not performed strictly or the speed profile stored in the microcomputer 4 becomes difficult to match due to load fluctuation or the like.

The present invention solves the conventional problems as described above, and provides a positioning device that can eliminate the influence of variations in offset voltage adjustment, load fluctuations, etc., and can stably converge residual vibration. That is the purpose.

Means for Solving the Problems Technical means of the present invention for solving the above problems include a servo signal detecting means for detecting a servo signal recorded on a medium, and a calculation based on the servo signal by the servo signal detecting means. A calculation means for outputting a correction value and a speed command value for the off-track amount, and a motor control / drive circuit for controlling and driving a motor for moving the magnetic head based on the output of the calculation means and the speed feedback value; A dead zone area setting means is provided for setting a dead zone area in which a motor current does not flow near a zero level of a motor current command in a settling mode subsequent to the speed control mode.

Therefore, according to the present invention, in the settling mode, the dead band is set near the zero level of the motor current command (input level), and the motor current is not supplied until the motor current command exceeding the dead band region is input. To do so. As a result, a stable settling operation can be performed without strictly adjusting the internal offset of the motor control unit and without being affected by the load fluctuation.

Examples Hereinafter, examples of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic block diagram showing the configuration of the main part of a positioning device according to an embodiment of the present invention.

The motor control / drive circuit 6 comprises a motor control circuit 6a, a motor drive circuit 6b, and a mode changeover switch 13. The motor drive circuit 6b includes an operational amplifier 9 that receives the output voltage of the motor control circuit 6a and the output voltage of the mode changeover switch 13, a Darlington transistor 10 that drives the positioning motor 7 using the output voltage V ₀ as a drive signal,
The resistors 11 and 12 are connected to the inverting terminal of the operational amplifier 9 and divide the output voltage of the mode changeover switch 13. The mode changeover switch 13 is changed over by the microcomputer 4 and applies a power supply voltage 12V to the resistor 11 or grounds it.

The operation of the above configuration will be described below. The operation of the entire system that drives the positioning motor 7 based on the detected servo signal will be described in the above second section.
Since it is the same as the description of the figure, redundant description will be omitted below.

In the speed control (seek) mode, when the magnetic head moves to the vicinity of the target track (about 1/4 track before), the microcomputer 4 switches the mode changeover switch 13 to the power supply 12V side to enter the settling mode. In this settling mode, the dead zone p is set in the same manner as in the position control mode as shown in FIG. When the input level is smaller than the dead zone p, the motor current does not flow.
However, when the dead zone p is exceeded, the motor current is passed. That is, in the settling mode, the relationship between the input voltage V ₁ and the output voltage V ₀ of the operational amplifier 9 can be expressed by the following equation.

(However, R ₁ is the resistance value of the resistor 12, and R ₂ = resistance value of the resistor 11) Here, when R ₁ << R ₂ is set, the following formula is established.

here, Then, the equation (2) becomes the following equation (3).

V ₀ ≈V ₁ −p (3) Here, p is the dead zone described above, which is smaller than the input voltage V ₁ of the operational amplifier 9 by the dead zone p, and a current is passed through the Darlington transistor 10.

As described above, according to the present invention, since the dead zone p is provided in the settling mode, the internal offset voltage of the motor control / drive circuit 6 is rigorously adjusted for each individual magnetic recording / reproducing device by a variable resistor or the like. Even if it is not, some variation can be tolerated, and stable settling operation can be performed. Further, even if the speed of entering the settling mode slightly fluctuates due to load fluctuations, stable settling operation can be performed without causing residual vibration or oscillation due to poor control of the motor current.

In this way, when the dead zone p is provided in the settling mode, the attenuation (stability) and responsiveness of the system are not reduced as compared with the case where the dead zone p is not provided, and exactly the same performance is obtained. And, it is extremely easy to obtain this configuration.

As described above, according to the present invention, the servo signal detecting means for detecting the servo signal recorded on the medium, the correction value for the off-track amount calculated based on the servo signal by the servo signal detecting means, and Calculating means for outputting a speed command value; a motor control / driving circuit for controlling and driving a motor for moving the magnetic head based on the output of the calculating means and the speed feedback value;
Since there is a dead zone area setting means for setting the dead zone area where no motor current flows in the settling mode following the speed control mode, near the zero level of the motor current command, the internal offset adjustment of the motor control section must be strictly performed. In addition, stable settling operation can be performed without being affected by load fluctuation.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing the configuration of the main part of a positioning device in an embodiment of the present invention, FIG. 2 is a schematic block diagram showing a conventional positioning device, and FIG. 3 is a waveform diagram showing its operation. FIG. 4 is a characteristic diagram showing the relationship between the input level and the motor current, and FIG. 5 is a motor current characteristic diagram in which a dead zone is provided for the input level. 1 ... Media, 2 ... Servo signal detecting means, 4 ... Microcomputer, 6 ... Motor control / drive circuit, 6a ... Motor control circuit,
6b ... Motor drive circuit, 7 ... Positioning motor, 9 ...
Op-amp, 10 ... Darlington transistor, 11, 12 ...
Resistance, 13… Mode changeover switch.

Claims (1)

(57) [Claims] 1. A servo signal detecting means for detecting a servo signal recorded on a medium, and a calculating means for outputting a correction value and a speed command value for an off-track amount calculated based on the servo signal by the servo signal detecting means. , A motor control / drive circuit for controlling and driving a motor for moving a magnetic head based on the output of this arithmetic means and a speed feedback value, and a dead zone region in which a motor current does not flow near a zero level of a motor current command. A positioning device having a dead zone region setting means for setting the speed control mode in a settling mode subsequent to the speed control mode.