JPH04217849A - Capstan motor - Google Patents

Abstract

PURPOSE:To make fine the magnitization pitch of pulse signal and to produce high output by making the outer peripheral part of servo signal recording part of vertical magnetic alumite and to suppress the influence of leakage flux from a driving part to the servo signal recording part thus enhancing heat resistance. CONSTITUTION:A driving part 2 for rotating a capstan shaft 1 is composed of magnetic material and fit over a supporting disc 4. A servo signal recording part 3 for controlling the rotational speed of the capstan shaft is applied on the driving part 2. The servo signal recording part 3 is subjected to alumite treatment and then immersed in sulfate solution where irons are electrolytically deposited to produce a vertical magnetic alumite. Since pulse signals are recorded through magnetization in the thicknesswise direction of the vertical magnetic alumite, magnetization pitch can be made fine resulting in high output.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capstan motor used, for example, in a video camera, and more particularly to an improvement in a servo signal recording section for controlling the number of revolutions.

0002

[Prior Art] For example, a capstan motor used in a video camera or the like to run a magnetic recording medium at a constant speed includes a capstan shaft for slidingly contacting the magnetic recording medium on its peripheral surface, and a capstan motor for driving a magnetic recording medium at a constant speed. An annular drive unit fixed to one end to rotate the capstan shaft, and a servo signal recording unit provided around the outer periphery of this drive unit, in which several hundred pulse signals for controlling the rotation speed are written. It is known that it is composed of

By the way, the servo signal recording section provided to keep the rotational speed of the capstan shaft constant is
Conventionally, it has been composed of a plastic rubber magnet, etc., and pulse signals are sequentially magnetized on the circumferential surface of the magnet in the form of N and S, and are read out by an MR sensor, etc., which is a read head placed opposite to the magnet. ing. Note that the pulse signal at this time needs to be 50 Oe or more depending on the sensitivity of the MR head.

[0004] In addition, in recent years, as the performance of the servo system of a video camera has improved, there has been a demand for finer division of the magnetization pitch recorded in the servo signal recording section. However, with plastic rubber magnets, it is difficult to subdivide the magnetization pitch, and it is becoming impossible to respond to the high performance of servo systems. Suppose that the magnetization pitch is changed from the conventional 200μm to 100μm.
Even if it is possible to do so, the reproduction leakage magnetic flux will rapidly decrease due to magnetic recording theory, etc., making it difficult to detect. Therefore, with plastic rubber magnets, the magnetization pitch cannot be further subdivided, and no improvement in servo control characteristics can be expected.

Furthermore, in the capstan motor, the servo signal recording section is susceptible to leakage magnetic flux from the drive section that rotates the capstan shaft, which is disadvantageous in terms of output. Furthermore, the servo signal recording section includes:
Since it is made of a plastic rubber magnet, it is extremely unstable at temperatures above 60°C due to expansion and contraction due to heat, which poses a problem in terms of reliability.

[0006]

[Problems to be Solved by the Invention] The present invention was proposed in view of the above-mentioned conventional circumstances, and it is an object of the present invention to provide a capstan motor in which the magnetization pitch of the pulse signal can be subdivided and high output can be expected. In both cases, it is an object of the present invention to provide a capstan motor that suppresses the influence of magnetic flux leakage from the drive section to the servo signal recording section and has excellent heat resistance.

[0007]

[Means for Solving the Problems] In order to achieve the above-mentioned objects, the present invention provides a capstan shaft on which a magnetic recording medium slides on the circumferential surface thereof, and an annular capstan shaft fixed to one end side of the capstan shaft. It consists of a driving part and a servo signal recording part provided around the outer periphery of the driving part and in which a pulse signal for controlling the rotation speed is written, and the outer periphery of the servo signal recording part is made of an alumite perpendicular magnetic material. That is.

[0008]

[Operation] The alumite perpendicular magnetic material is produced by subjecting aluminum to alumite treatment, immersing it in, for example, a sulfate solution, and applying an electric current to electrolytically deposit iron. The alumite perpendicular magnetic material thus formed is formed vertically in the thickness direction and has a superacicular shape. and,
This alumite perpendicular magnetic material can be magnetized only in the film thickness direction. Therefore, in the present invention, since the pulse signal is recorded by magnetizing the alumite perpendicular magnetic material in the film thickness direction, the magnetization pitch can be finely divided, and high output can be achieved.

Furthermore, in the present invention, since the alumite perpendicular magnetic material is provided on the outer periphery of the servo signal recording section, it is located away from the drive section, and leakage from the drive section to the alumite vertical magnetic material is prevented. The influence of magnetic flux is suppressed.

0010

[Embodiments] Specific embodiments to which the present invention is applied will be described below. Note that this embodiment is an example of a capstan motor that directly drives a capstan shaft.

First, a capstan motor according to a first embodiment will be explained with reference to FIGS. 1 to 3. As shown in FIGS. 1 and 2, the capstan motor of this example includes a capstan shaft 1 on the circumferential surface of which a magnetic recording medium slides, and a drive section 2 fixed to one end of the capstan shaft 1. The main component is a servo signal recording section 3 provided around the outer periphery of the drive section 2 and in which pulse signals for controlling the rotation speed are written.

The capstan shaft 1 is used, for example, in a video camera or the like, to press a magnetic recording medium onto the peripheral surface thereof in cooperation with a pinch roller, and to cause the magnetic recording medium to travel at a constant speed. Therefore, the capstan shaft 1 is selected to be hard and free from rust and magnetization, and is usually made of stainless steel or the like. In addition,
After the capstan shaft 1 is made of stainless steel, the stainless steel is heat treated, and then the peripheral surface is polished to a mirror finish by several times of grinding and lapping. In addition, the capstan shaft 1 is
If the circumferential speed of the shaft is uneven, the running speed will be uneven, causing wow and flutter, so the roundness is highly accurate at several μm.

The drive section 2 is for rotating the capstan shaft 1 in cooperation with, for example, a magnet provided on a substrate, and is made of a magnetic material such as a magnet, and is configured to record the magnetic recording of the capstan shaft 1. It is provided on the other end side opposite to the tip portion that makes sliding contact with the medium. That is, the drive section 2 is provided so as to be fitted around the outer periphery of the disk-shaped support member 4 fixed to the other end side of the capstan shaft 1.

A servo signal recording section 3 for controlling the rotation speed of the capstan shaft 1 is provided around the outer periphery of the driving section 2. The servo signal recording section 3 is made of annular aluminum and is provided around the outer periphery of the drive section 2 with an insulating layer 5 in between to prevent magnetic coupling with the drive section 2. Note that the servo signal recording section 3, the driving section 2, and the supporting member 4 all have substantially the same thickness.

The outer peripheral portion 3a of the servo signal recording portion 3 is an alumite perpendicular magnetic material formed by electrolytically depositing iron in, for example, a sulfate solution after alumite treatment. A pulse signal for detecting the rotational speed of the capstan shaft 1 is written in this alumite vertical magnetic material. The alumite perpendicular magnetic material is, for example, alumite treated on the surface of aluminum having a purity of 4 nines (99.99%) or higher, that is, on the circumferential surface of the servo signal recording section 3, and then treated with Fe, Ni, C.
It is formed by immersing it in a sulfate solution or an oxalate solution containing 0, etc., and applying an electric current to electrolytically deposit Fe, which is a magnetic metal. In other words, the alumite perpendicular magnetic material is formed by depositing Fe in pores that are formed in the film thickness direction when aluminum is subjected to alumite treatment. Therefore, the magnetic material deposited in the pores has a large length-to-width ratio, exhibits a superacicular ratio, and exhibits the property of being magnetized only in the film thickness direction.

In this example, the film thickness of the alumite perpendicular magnetic material is 50 μm to 50 μm, taking into account the time to magnetize the pulse signal.
The thickness was about 20 μm. A thickness of this level is advantageous in terms of productivity because the time required for magnetization is short.

[0017] Since the recording of the pulse signal recorded on the alumite perpendicular magnetic material results in magnetization in the film thickness direction of the alumite perpendicular magnetic material, it is possible to achieve finer division of the magnetization pitch and achieve higher output. . In this example, the magnetization pitch is 10
It can be made from μm to 100 μm or less, and can be expected to have several times higher output than conventional plastic rubber magnets. Furthermore, since the alumite perpendicular magnetic material is located at a distance from the drive section 2 and is magnetized only in one direction, it is hardly affected by leakage magnetic flux from the drive section 2. Additionally, the alumite perpendicular magnetic material is resistant to heat and has excellent reliability.

In the capstan motor configured as described above, the magnets disposed on the substrate and the drive section 2 are arranged opposite to each other with a predetermined interval, and the cooperation between these magnets and the drive section 2 causes It is designed to rotate in the circumferential direction. For example, an MR head or the like is provided opposite to the outer peripheral part 3a of the servo signal recording part 3 provided on the outer peripheral part of the drive part 2, and this MR head writes on the alumite perpendicular magnetic material of the outer peripheral part 3a. The pulse signal is read out. Since the pulse signal at this time is extremely finely divided, the capstan shaft 1
The rotation of the capstan shaft 1 can be finely controlled, and the capstan shaft 1 can always be rotated at a constant rotation speed.

Next, a capstan motor according to a second embodiment will be explained with reference to FIGS. 4 and 5. As shown in FIG. 4, the capstan motor of this example has a servo signal in which a pulse signal for controlling the rotation speed is written on the outer periphery of a disk-shaped drive unit 7 directly fixed to one end side of a capstan shaft 6. A recording section 8 is provided.

As shown in FIG. 5, the servo signal recording section 8 has an aluminum film with a thickness of 50 mm around the outer periphery of the driving section 7.
It is vapor deposited or sputtered to a thickness of about 100 μm. The surface 8a of the servo signal recording section 8, that is, the surface of the aluminum thin film, is made of an alumite vertical magnetic material as in the capstan motor of the first embodiment, and the capstan shaft 6 is formed on this alumite vertical magnetic material. A pulse signal is written to detect the rotation speed of the motor.

[0021] The alumite perpendicular magnetic material is formed by vapor-depositing or sputtering high-purity aluminum around the outer periphery of the disc to a thickness of about 50 to 100 μm, and then anodizing it in the same manner as in the previous example. , iron is deposited by electrolytic field in a sulfate solution, etc. In particular, if aluminum is vapor-deposited or sputtered, a highly pure aluminum thin film can be obtained, and the needle-like cavities (pores) after alumite treatment are ideal. In other words, when machining aluminum, impurities tend to enter during processing and hinder the acicularity, but when vapor deposition is performed in a vacuum, there is no contamination of impurities.

Therefore, in the capstan motor of this example, the magnetic properties are further improved, and high resolution and high output can be expected. Further, in the capstan motor of this example, since the aluminum thin film is extremely thin with a thickness of 50 to 100 μm, the amount of expensive aluminum used can be reduced, which is advantageous in terms of cost.

[0023]

Effects of the Invention As is clear from the above description, in the capstan motor of the present invention, recording of pulse signals for controlling the rotation speed of the capstan shaft is performed in the direction of the film thickness of the alumite perpendicular magnetic material. To be made with magnetization,
The magnetization pitch can be finely divided, and high output can be achieved.

Furthermore, in the present invention, since the alumite perpendicular magnetic material is provided on the outer periphery of the servo signal recording section, it is located away from the drive section, and leakage magnetic flux from the drive section to the alumite vertical magnetic material is prevented. The impact of this can be suppressed. Furthermore, since the alumite perpendicular magnetic material is resistant to heat, it is also advantageous in terms of reliability.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an example of a capstan motor to which the present invention is applied.

FIG. 2 is a cross-sectional view of FIG. 1;

FIG. 3 is an enlarged view of essential parts showing the outer circumference of the servo signal recording section in FIG. 1;

FIG. 4 is a perspective view showing another example of a capstan motor to which the present invention is applied.

FIG. 5 is an enlarged view of main parts showing the outer circumference of the servo signal recording section of FIG. 4;

[Explanation of symbols]

1, 6... Capstan shaft 2, 7... Drive section 3, 8... Servo signal recording section 3a, 8a... Outer periphery of servo signal recording section (alumite perpendicular magnetic material)

Claims (1)

[Claims] 1. A capstan shaft on which a magnetic recording medium slides on the circumferential surface, an annular drive section fixed to one end of the capstan shaft, and a drive section provided around the outside of the drive section to control the rotation speed. 1. A capstan motor comprising a servo signal recording section in which a pulse signal is written, and an outer circumference of the servo signal recording section is made of an alumite perpendicular magnetic material.