JPS6192420A - Disk plate for magnetic recording - Google Patents

Abstract

PURPOSE:To suppress the warpage of a thin magnetic plate by a substrate and to decrease a gap fluctuation and read errors by adhering said magnetic plate to the substrate consisting of a high permeability material and having high rigidity. CONSTITUTION:The magnetic plate which consists of an Fe-Cr-Co magnetic material and is thinner than the substrate consisting of the high magnetic permeability material is adhered to at least one surface of the substrate. The manufacture of a disk plate 10 is executed by blanking first the high permeability alloy by pressing, then subjecting the blanked alloy to rough grinding and polishing to form the substrate 10A having warpage within 5mum, adhering the magnetic plate 10B to one side of such substrate 10A by using an adhesive agent such as epoxy resin and polishing lightly the surface of such magnetic plate 10B. The substrate 10A has the substantial rigidity with such disk plate 10 and even if the plate 10B is thin, the rigidity as a whole is high and further the warpage of the substrate 10A is <=5mu and since the plate 10B adhered to the substrate 10A is polished, the generation of the warpage to the plate 10B in the stage of working is obviated.

Description

[Detailed Description of the Invention] [Field of Medical Application] The present invention relates to a magnetic disk plate, and by constructing it from a substrate and a magnetic plate, it is possible to reduce the overall warpage and obtain a sufficiently large signal output. It has been made possible.

〔Servant of the United States〕

Among rotary encoders, which are indispensable sensors for servo control, this type detects the rotational displacement of motors, etc. by detecting signals magnetically recorded on the periphery of a disc plate made of abrasive material using a magnetic sensor. Magnetic rotary encoders are known. Conventionally, the disk plate used in this type of rotary encoder is made of a hard magnetic material and a workable Fe-Cr-0 material.
Discs made of 0-series alloys have been used, but in recent years there has been a trend to make the diameter smaller in order to further improve resolution.
In order to suppress the increase in inertia during rotation due to larger sizes, there is a trend towards thinner walls.

[Problem that the invention seeks to solve]

As the disk plate becomes larger and thinner as described above, in addition to the warpage of the disk plate material itself, the warpage caused by the polishing process performed during the manufacture of the disk plate causes the warpage between the disk plate and the magnetic sensor. There was a problem in that the distance (hereinafter referred to as the gap) fluctuates when the disk plate rotates, increasing reading errors.

Incidentally, in the rotary encoder schematically shown in FIGS. 4 and 5, magnetic scales (magnetic signals) are formed by N magnetizing in the thickness direction of the periphery of the disk plate 10 or on the circumferential surface at a pitch of j0 to 100t1m. Then, a magnetic sensor 2 is installed at a position 2 to 10 μm 14a away from the surface of this disk plate 10) layer m.
The magnetic sensor reads the magnetic signal of the disk plate l and outputs the read content as a voltage change. However, in the rotary encoder described above, if the warpage of the disk plate 1 is large, the gap fluctuation caused by the rotation of the disk plate 1 will appear as a change in the output voltage, which may cause a reading error. The warpage must be kept within 5μ.

[Purpose of the invention]

This invention has been made in view of the above-mentioned circumstances, and provides a magnetic recording disk plate that can suppress warpage within a range that does not cause errors in reading magnetic signals and can also obtain a sufficient output voltage. purpose.

[Means for Solving the Problems] The present invention is characterized in that a magnetic plate made of a Fe-0r-Co magnetic material and thinner than the above substrate is adhered to at least one side of a substrate made of a localized magnetic permeability material. .

[Effect]

The highly rigid substrate rams the warpage of the magnetic plate, and
The size ratio between different poles of the magnetic signal formed in the i-type root is increased to control the output signal.

〔Example〕

1 to 3 show an embodiment of the present invention, in which numeral 10 indicates a rotary encoder disk plate, and numeral 11 indicates a magnetic field for reading the magnetic signal P formed on the peripheral edge 10a of this disk plate 100. A magnetic sensor such as a resistive element is shown. The disk plate lO has a thickness of, for example, 0.
A disc-shaped substrate 10A made of 5 to 0.7 silk and made of a high magnetic permeability alloy (for example, 78 qbNl - balance Fe (iron) or 45 qbN1 - a part Fe), and this substrate 10A. , the thickness is, for example, 0.1 to 0.31;l, and Fe-Cr
-G O-based magnet alloy (spinodal decomposition type magnet alloy)
It consists of a magnetic plate 10B consisting of. The peripheral edge 10a of the disk plate 100 is provided with 30 mm along the circumferential direction.
Magnetic signals P... are formed at a pitch of ~100 μm. These magnetic signals P are generated intermittently at a predetermined pitch along the circumferential direction of the peripheral edge 10a of the disk plate 10, and the cone of each magnetic signal P appearing on the surface of the disk plate 100 is alternately different between adjacent ones. like! It is formed magnetically.

In order to manufacture the disk plate IO, first, a high magnetic permeability alloy is press-punched, then roughly ground and polished to form a substrate 10A with warpage within 5 μm.
A magnetic plate 10B is bonded to one side of the disk using an adhesive such as epoxy resin, and the surface of this magnetic plate jOB is lightly polished.
Since A has sufficient rigidity, the overall rigidity is high even if the magnetic &lOB is thin.Furthermore, the warpage of the substrate 10A is less than 5μ, and the magnetic plate JO bonded to this substrate 10A
Since B is subjected to the polishing process, the magnetic plate 10B is not warped during processing.

Therefore, the gap 'i movement between the magnetic sensor 11 and the magnetic plate 10B can be predicted to be low, the fluctuation in the output voltage is also small, and the welt removal can be performed accurately.

In addition, the above y opening <30 to 1100 on the thin magnetic plate 10B
When magnetized with a 1J pitch, if only the magnetic plate 10B that is not integrated with the substrate 10A is magnetized, the magnetic plate 103
Although the dimensional ratio between the north pole and the south pole occurring on the front surface and the rear surface of the disk plate 10 is not large, in this case, since the substrate 10 made of a high magnetic permeability material is integrated in the disk plate 10, , the dimensional ratio is approximately twice that of the case where the magnetic plate 10B is one piece, and the surface m'5Krw degree of the magnetic signal P is also the same as that of the conventional product, making it possible to obtain a sufficient output voltage. .

Note that the N pole and the 8
The ratio of the signal dimension between the magnetic signals P and the magnetic signals P arranged in the circumferential direction of the magnetic plate 10B, that is, the value of (N-B dimension/signal dimension) is Fe − Cr − For CO-based magnetic materials, it is necessary that the value is 5 or more. Further, the lower limit of the rotor-to-rotor dimension is determined by the reading resolution of the magnetic sensor. Therefore, in order to make the value of the above (dimension between N-8/dimension between IM) 5 or more, it is necessary to increase the dimension between N-8, and this determines the lower limit of the thickness of the disk plate 10, and further It is preferable that the upper limit of the plate thickness is such that the inertia of the disk plate 10 is not too large. Therefore, in the above embodiment, the signal amount dimension is set to 30 to 100 μm, and the thickness of the disk plate 10 is set to 0.6 to 1.5 μm. It was set as 0 舅凰.

On the other hand, in the above embodiment, the magnetic signal P is formed on the peripheral edge 10a of the disk plate 100, but the magnetic signal P may be formed on the surface of the disk plate IO.

Furthermore, the substrate 10A and the magnetic plate 10B may be bonded together by means such as pressure bonding.

In addition, the Fe-0r-QQ-based magnet alloy has a coercive force (HC)
Although the residual magnetic flux density (Br) is slightly lower than that of ferrite magnets or rare earth magnets, the residual magnetic flux density (Br) is sufficiently high, so it is recommended to integrate it with the substrate 10A as in the above embodiment and use it with a large dimensional ratio between N-8. It is advantageous to use a Fe-0r-co based magnet alloy for the disk plate 10.

〔Effect of the invention〕

As explained above, in this invention, a thin magnetic plate is bonded to a highly rigid substrate made of a material with high magnetic permeability, so that the substrate suppresses the warping of the magnetic plate, and thereby serves as a magnetic sensor for recording self-reading. By reducing the gap reaction generated between the magnetic plate and the magnetic plate, Uf and machining errors can be reduced. Furthermore, since the substrate made of a high magnetic permeability alloy increases the dimension between different polarities of the magnetic signals recorded on the magnetic plate, the output signal increases and sufficient output pressure can be obtained.

[Brief explanation of the drawing]

1 is a side view showing a disk plate according to an embodiment of the present invention; FIG. 2 is a side view showing the state in which the disk plate shown in FIG. 1 is used; FIG. 3 is a plan view of FIG. 2; The figure is a side view showing an example of a conventional disc plate in use, and Figure @5 is a plan view of Figure 4. 10... Disk board, lOA... Board, IOB...
・Magnetic plate, P...magnetic signal

Claims (1)

[Claims] At least one side of the substrate made of a high magnetic permeability material is made of Fe-Cr.
- A magnetic recording disk plate, characterized in that a magnetic plate made of a Co-based magnetic material and thinner than the substrate is adhered to the magnetic plate, and a magnetic signal is recorded on the magnetic plate.