JP2579805B2 - Positioning device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a positioning device for moving a magnetic head on a desired track of a magnetic disk in a magnetic recording / reproducing device or the like.

(Prior Art) Conventionally, a positioning device for moving a magnetic head on a desired track of a magnetic disk is configured as shown in FIG. 2, and a positioning motor 7 is provided with a coarse seek using an encoder built in the motor. (Open loop seek) and fine movement for performing alignment by a servo signal recorded on the medium to correct off-track.
Positioning is performed by the same seek operation.

Therefore, as shown in FIG. 3 (a), as an example, the behavior of the magnetic head when a 5-track seek is performed, after the data is sent on the basis of the encoder of the motor, the servo signal of the medium is used to perform the alignment to complete the seek. However, when the seek starts, the motor starts from the position (x mark; media servo signal reference on-track position) positioned based on the servo signal reference of the medium, and starts from the next track with the motor encoder reference (○ mark; motor encoder reference). On-track position). The position at which the track is switched is the top of the encoder signal, but it is necessary to set the threshold level slightly lower in consideration of variations in signal amplitude and the like (△: position corresponding to the threshold level for creating a track count signal). .

Further, the command value of the speed control by the D / A converter 5 from the microcomputer 4, as shown in FIG. 4, for each predetermined voltage threshold levels V _T of the position signal of the encoder 8, the motor drive and control circuit 6 Given to.

At almost the same timing, the microcomputer 4 counts the number of track movements in the seek.

(Problems to be Solved by the Invention) However, in the above-described conventional positioning apparatus, in order to seek from the on-track based on the servo signal on the medium at the start of the seek, the on-track based on the motor encoder and the medium are determined by thermal off-track or the like. If the deviation of the on-track based on the above servo signal becomes large, the timing of the track count is shifted, and a seek error occurs due to a count error of the number of seek tracks. For example, as shown in FIG. 3 (a), when the deviation amount of the media servo signal reference on-track position x from the motor reference encoder on-track position 小 さ く is small and is between ○ and △, the track count is 5 However, as shown in FIG. 3 (b), as shown in FIG. 3 (b), when the deviation amount of X from the circle is large, and when the track count is outside the circles and △, the track count is 5, but 6 track seek is performed. A count error occurs. In addition, there is a problem that the timing at which the speed command value is given is shifted and proper speed control cannot be performed. In FIG. 2, the D / A conversion command value given to the motor drive / control circuit 6 for accelerating and decelerating a motor suitable for each number of tracks to be sought is set when there is no off-track, that is, when the on-track position is based on the encoder. It is stored in the microcomputer 4 in the form of a table based on the moving distance.
In particular, the shown manner to FIG. 5 of the position signal of the encoder when seeking one track, when the off-track is small {FIG. 5 (a)} is a timing t ₁ is set as relative operation of the motor However, when the off-track is large as in the cases of FIGS. 5B and 5C, the timing becomes longer or shorter than the timings t ₂ , t ₃ and t ₁ . Therefore, the D / A conversion command value for one track stored in the microcomputer 4 is insufficient for acceleration and stops halfway, runs too fast due to excessive acceleration, and tends to generate residual vibration. For example, the motor may not be able to reach the target track, causing a seek error, and is not appropriate for the movement of the motor.

The present invention solves such a problem,
Regardless of whether the off-track is large or small, there is no possibility that the count of the number of moving tracks is erroneously counted at the time of seek and a seek error occurs, and stable speed control can be performed by always giving a speed command at an appropriate timing. It is an object to provide an excellent positioning device.

(Means for Solving the Problems) According to the present invention, in order to achieve the above object, at the start of a seek, the medium is temporarily moved from the on-track position based on the servo signal of the medium to the on-track position based on the encoder of the motor (reset). And then seek.

(Operation) Therefore, according to the present invention, the seek of the moving track count is erroneously performed at the seek by moving (resetting) to the on-track position based on the motor encoder once and then seeking. By providing a speed command always at an appropriate timing, there is an effect that stable speed control can be performed.

FIG. 1 shows an encoder position signal according to an embodiment of the present invention. FIG. 2 can be applied as it is to the circuit configuration. In FIG. 2, 1 is a medium, 2 is a servo signal detection circuit for detecting a servo signal recorded on the medium 1, 3 is an A / D converter for converting the servo signal into a digital signal, and 4 is a microcomputer; A command value for calculating the off-track amount and its correction amount from the digital signal, or for controlling the speed during seek, is determined by the difference between the number of tracks to be sought and the number of tracks actually moved (the remaining tracks to be sought). Number) is stored as a table. Reference numeral 5 denotes a D / A converter for converting an off-track correction amount and a speed control command value from a microcomputer into an analog signal. Reference numeral 6 denotes a motor drive / control circuit which converts the analog signal into a current and performs feedback control. A positioning motor (DC) that moves the head to the desired track
Servo motors) and 8 are encoders (optical one-phase encoders) mounted coaxially with the motor 7.

 Next, the operation of this embodiment will be described.

1 and 2, when an off-track occurs between the medium 1 and the head of the servo signal detecting means 2, the microcomputer 4 controls the D / A converter so as to follow the servo signal recorded on the medium 1. Since the motor 7 is moved through 5,
The position signal of the encoder 8 performs a follow-up operation at a position deviated from the reference position. In this state, when the seek operation is started, each of the R signals shown in FIGS. 1 (a), (b) and (c) is used. As described above, from this shifted state, the motor 7 is once operated by a command to the D / A converter 5 of the microcomputer 4, and the seek operation is performed after returning to the reference value of the position signal of the encoder (reset). In order to perform such an operation, as shown in FIG. 3 (c), even if the amount of deviation of x from the circle is large and is outside of circles and triangles, the track count is 5 points.
Then, count normally.

(Effects of the Invention) The present invention has the following effects, as is clear from the above-described embodiments.

(1) Even if the off-track amount is large, seek error can be prevented because the motor encoder reference is reset.

(2) Even if the off-track amount is large, speed control can always be performed at a uniform timing because the motor encoder reference is reset.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the operation of one embodiment of the present invention, and FIG.
FIGS. 3 to 5 are block diagrams showing the configuration of the positioning device, and are explanatory diagrams of the operation of the conventional example. 1 ... Media 2 ... Servo signal detecting means (including head) 3 ... A / D converter 4 ... Microcomputer 5 ... D / A
Converter, 6 ... Motor drive / control circuit, 7 ... Positioning motor, 8 ... Encoder.

Claims (1)

(57) [Claims] A servo signal detecting means including a magnetic head for detecting a servo signal recorded on a medium; an A / D converter for converting the detected servo signal into a digital signal;
A microcomputer and a D / A converter for calculating an off-track amount from a digital signal, outputting a correction value for the off-track amount, and outputting a command value for performing speed control during a seek; and A positioning motor such as a DC servo motor or a voice coil motor for moving to a desired track, an encoder for detecting the rotational position of the motor, and a means for controlling the drive of the motor. A positioning device comprising a control means for temporarily moving from an on-track position based on a servo signal to an on-track position based on an encoder of a motor, resetting, and then seeking.