JPS6273467A - Rotary magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve the required resolution of a step motor by controlling a current ratio flowing to an exciting coil of the 2-phase step motor without increasing the mechanical resolution per one phase of the step motor. CONSTITUTION:The range of excitation of the 2-phase step motor is provided to >=2 tracks at an angle corresponding to <=90% of rotary angle per phase in a range excluding an angle of 5% around one phase exciting portion. Thus, the exciting relation positioning the track position for >=2 tracks in the 2-phase excitation is formed on the exciting current around one phase of the 2-phase step motor except the nonlinear portion of the head position. Thus, the track number and track density are improved without improving the mechanical resolution per phase.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to track excitation of a rotary magnetic recording/reproducing device.

[Conventional technology]

As shown in FIG. 2, a conventional rotary magnetic recording/reproducing apparatus having a two-phase step motor is equipped with a stay belt 21 that converts a rotary motion of a two-phase step motor 22 into linear motion for a head 20 that performs magnetic recording and reproduction. It has a head drive mechanism consisting of. Each phase of the two-phase step motor 22 is
As shown in FIG. 3a, transistors 24, 25, 26,
A current is supplied to the excitation coil 28 of the step motor 22 by a circuit called a bipolar circuit composed of 27. The amount of current is limited by the power supply voltage 25 and resistor 29,
Furthermore, the direction of the current flowing through the excitation coil 28 can be freely determined by controlling each transistor. For example, by turning on the transistors 26 and 25 and turning off the transistors 24 and 27, the current flows from the voltage to the right in the drawing. By providing the circuit 30 twice, as shown in FIG. 5b, the coils 28 of each phase of the step motor 22 can be controlled, and the rotation and stop of the step motor 22 can be controlled.

[Problem that the invention seeks to solve]

However, in the conventional technology described above, it is necessary to determine the track at a position determined by a combination of two-phase excitation and one-phase excitation in order to control the two-phase step motor. It becomes necessary to increase phase resolution. The resolution of one phase is 1.8 degrees/phase or 0.9! E' phase is commonly used, but
- In order to increase the resolution considerably, it is difficult to manufacture a step motor with a fine pitch of teeth, so 0.
Highly accurate manufacturing with a resolution of 451f/phase or higher is
The cost is high and it is difficult to create a market.

The present invention is intended to solve these problems, and its purpose is to improve the resolution of the step motor as the number of tracks and track density increases, without increasing the mechanical resolution per step motor. The goal is to provide ways to increase the

[Means for solving problems]

The rotary magnetic recording/reproducing device of the present invention excite a two-phase step motor to move two or more tracks at an angle corresponding to within 90% of the rotation angle per phase, and to
It is characterized by being provided in a range excluding the angle of %.

[Function] According to the present invention, by controlling the current ratio flowing through the excitation coil of the two-phase step motor, the number of tracks and the track density can be increased without increasing the mechanical resolution per step motor. It is possible to increase the resolution of the step motor required for

〔Example〕

An embodiment of the invention is shown in FIG. 1b. CPU9,D
, /A converter 10, excitation circuit 11, two-phase step motor 22, and excitation coil 28, 0FU
9 outputs the digital amount as a control amount. This is D
/A converter 10 converts it into an analog quantity, and the excitation circuit 11 is current-controlled by the analog quantity. As an example of the excitation circuit 11, the transistor 25 shown in FIG.
There is a method of controlling 27 in a linear region. This results in 2
The current flowing through the excitation coil 28 of the phase step motor 22 is D.
It can be changed digitally with precision determined by the resolution of the /A converter 10. There are two excitation coils 28 in a two-phase step motor, and if they are designated as A phase and B phase, the current determined by the resolution of the D/A converter 10 can be controlled for each phase, and by this combination, the two-phase step The stopping position R of the motor can be determined. This is illustrated in Figure 1a. The current for both the A phase and B phase can be changed in one direction, and the excitation angle can be changed by a D/A converter. Although expressed as + and - here, if a certain current direction is 0, the opposite direction is -, so it is not an absolute direction. At track position 1, the A phase is α in ten directions.
If a current of the amount β is passed in the B phase in ten directions, the head 20 will come to the excitation position determined by the track position 1.

Similarly, the two-phase step motor 22 can be stopped by applying the direction and circulation amount of each AB phase at track positions 2, 5, 4, 5, 6, 7, and 8 to the electrodynamic coil 28. In this way, the combination of the D/A converter 10 and the excitation circuit 110 can control the current flowing to the A and B phases, and the head position can be adjusted to just one phase.

It can be stopped not only at a specific position called 2-phase, but also at any position. FIG. 4 shows the relationship between the excitation angle and the head position. This is an example in which the excitation angle is changed from a state in which only the incoming phase is excited to a state in which only the B phase is excited by changing the ratio of current flowing to the A and B phases, and the position of the head at that time is plotted. The position of the head changes in proportion to the excitation angle from excitation angle A to B, but the position of the head moves significantly near one phase.

This varies depending on the shape of the step motor teeth, but
Generally, there is development in which such a proportional relationship breaks down near one phase. Furthermore, in the combination of the excitation circuit and the D/A converter, linearity may deteriorate in a range where the amount of current is small.

It is fully possible to suppress the excitation angle at which this proportional relationship breaks down to within 5% of the phase rotation angle. Therefore, Kl a
As shown in the figure, in order to position two tracks between one phase, it is only necessary to establish track positions at every 45 degrees of excitation angle, and this is possible. Furthermore, it is also possible to divide into three or more tracks so as not to use an excitation angle that destroys the proportional relationship in the vicinity of one phase.

〔Effect of the invention〕

As described above, according to the present invention, the excitation relationship that determines the trunk position of two or more tracks within the two-phase excitation is established between the excitation current near the first phase of the two-phase step motor and the non-linear portion of the head position. can be made. Therefore, there is an effect that the number of tracks and the track density can be improved without increasing the mechanical resolution per phase.

[Brief explanation of drawings]

FIG. 1(a) is a diagram showing the relationship between the current flowing through the phases and the track position according to the present invention. FIG. 1(1+) is a block diagram of the circuitry necessary to carry out the present invention. FIG. 2 is a rotary type % type equipped with a two-phase step motor. FIG. 3(a) is a conventional excitation coil drive circuit diagram. FIG. 3(b) is a two-phase step motor drive block diagram; FIG. 4 is a diagram showing the relationship between the excitation angle and the head position. 1-8...Track position 9...C'PU 10...D/A converter 11...Excitation circuit 20...Head 21 ...Steal belt 22 ... Two-phase step motor 23 ... Power supply 24 to 27 ... Transistor 28 ... Excitation coil 29 ... ...Resistor 30...Excitation circuit α, β...Current amount A, B...Excitation angle - = 4 (1 41-Figure 1 (,
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Claims (1)

[Claims] In a rotary magnetic recording/reproducing device having a two-phase step motor as a head drive mechanism, two or more tracks are arranged at an angle corresponding to within 90% of the rotation angle per phase, and two or more tracks are arranged at an angle corresponding to within 90% of the rotation angle per phase, and at an angle of 5% near one-phase excitation. A rotary magnetic recording and reproducing device characterized in that it is provided at an excitation angle, except for.