JPH0264975A - Arm for magnetic head - Google Patents

Abstract

PURPOSE:To reduce off-track by providing both a temperature sensor and a heating member and controlling the heating quantity of the heating member in correspondence to the output of the temperature sensor. CONSTITUTION:When heating is executed by a heating member 10a which is provided in an arm 1 for head, the arm is thermally expanded and stretched. Here, when the heating quantity is controlled, the arm 1 can be thermally expanded only by the prescribed quantity. Further, when a temperature sensor 11 is added to the arm 1 and the heating quantity of the heating member 10a is controlled in correspondence to the output of the sensor 11, it is possible to change thermal expansion quantity in correspondence to a temperature or to control the temperature of the arm 1. Accordingly, since the termal expansion of the arm 1 can be freely executed, in case there are the plural arms 1 of the different temperatures, the temperature or termal expansion quantity of the arm 1 can be made same by controlling the heating quantity of the arm 1. Thus, the off-track can be reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the temperature or thermal expansion (elongation) of a magnetic head arm.
This invention relates to preventing off-track of a magnetic head through adjustment.

[Conventional technology]

The conventional device forms a composite body in which a head arm and a resin having a different coefficient of thermal expansion are integrated in a layered manner, as described in JP-A-61-123068.
The coefficient of thermal expansion (equivalent to elongation) of the entire head arm was adjusted.

[Problem to be solved by the invention]

Although it is possible to obtain head arms having various coefficients of thermal expansion with the above-mentioned conventional techniques, it is not possible to freely adjust the thermal expansion from time to time in accordance with temperature changes.

In other words, once the head arm is initially set to a certain coefficient of thermal expansion, the amount of expansion is automatically determined by the temperature, and it is not possible to freely select an arbitrary expansion depending on the situation.

An object of the present invention is to enable the thermal expansion (elongation) of a head arm to be freely adjusted depending on the situation. In particular, in a magnetic disk drive having a plurality of head arms, the elongation of each arm can be adjusted freely. The purpose of this adjustment is to reduce off-track.

[Means to solve the problem]

In order to achieve the above purpose, a heating member such as a nichrome wire is installed on the head arm, and the head door arm is heated according to the situation.Furthermore, a 2 degree sensor is installed, and the output of the sensor is The heating amount of the heating member is adjusted accordingly.

[Effect]

When heated by the heating member provided on the head arm, the head arm thermally expands and stretches. here.

By adjusting the amount of heating, the head arm can be thermally expanded (stretched) by a predetermined amount.Furthermore, a temperature sensor is added to the head arm, and the amount of heating of the heating member is adjusted according to the output of the sensor. By doing so, it is possible to change the amount of thermal expansion depending on the temperature and to control the temperature of the head arm. This allows the head arm to thermally expand freely, so if there are multiple head arms with different temperatures, by adjusting the amount of heating of each arm, the temperature of the arms can be kept the same.
Alternatively, the amount of thermal expansion can be made the same, and off-track can be reduced.

[Example] An example of the present invention will be described below with reference to the drawings. 1 and 2 show an embodiment of the head arm of the present invention. In these figures, 1 is the head arm, 2 is the arm body, and the magnetic head 3 is attached to the tip of the arm, and the load arm 4 is attached to the tip. It is attached through. On the other hand, a mounting hole 5 is provided at the base of the arm body 2, and the arm body 2 is fixed to a carriage (not shown in the figure) for moving and positioning the magnetic head 3 with screws or the like. 6 is an FPC (FPC) in which a foil lead wire 7 is layered in a sandwich-like manner with two resin sheets 8a and 8b.
The entire shaded area in FIG. 1 is the FPC 6.

The FPC 6 is mounted on the arm body 2 with an adhesive 9 to constitute the head arm 1.

A heating member 10a is provided in the FPC 6 of the present invention, and is made of a box-shaped resistor such as nichrome or stainless steel foil. In addition, the figure shows an example in which a temperature sensor 11 is also provided.Heating member 10a of the present invention and temperature sensor 11
It is preferable to provide the lead wire 7 in the same place as the lead wire 7 in the FPCB layered with two resin sheets 8a and 8b as shown in FIG. There may be three resin sheets 8a and 8b in FIG. 3.

8C, the position where the lead wire 7 is provided and the position where the heating member 10a and temperature sensor 11 are provided are separated, and 41
The FPC 6 is made up of three layers of 1 fat 8. Of course, the FPC 6 may have three or more layers if it can be made thinner, and FIG. 4 shows an FPC with lead wires 7.
There is another FPC 6 on the opposite side of the arm body 2 from 6a.
b.

This is an example in which a heating member 10a and a temperature sensor 11 are provided. FIG. 5 shows an example in which, contrary to FIG. 4, an FPC 6 is provided between the arm bodies 2a and 2b which are divided into two parts, and a lead wire 7, a heating member 10a, and a temperature sensor 11 are provided therein. Although FIGS. 2 to 5@ show an example in which the FPC 6 is bonded to the arm body 2 with the adhesive 9, the installation of the FPC 6 is not limited to this, and may be partially fixed using screws, etc. Heating member 10a and temperature sensor 11
may be exposed to the outside from the FPC 6 as long as the covering is sufficient, and may be in direct contact with the arm body 2, or may be brought into contact intentionally.

The temperature sensor 11 is preferably small, and may be composed of a thermocouple, a thermistor, or the like.

Alternatively, a resistor may be provided as the temperature sensor 11 and the temperature may be determined by measuring the resistance.The wiring pattern between the temperature sensor 11 and the heating member 10a within the FPCe is provided so as to pass through the necessary gaps between the lead wires 7. Here, the heating member 10a is provided only in the FPCe bonded to the arm body 1, and the wiring pattern shown in Fig. 1 is an example, and the wiring pattern is not limited to this. Also, the coefficient of thermal expansion of FPC6 is the same as that of arm body 2.
It is desirable that it be as similar as possible. For example, the arm body 2 is made of aluminum alloy and has a coefficient of thermal expansion of 23.5 x 10.
If it is about -6, the FP including resin 8, lead wire 7, etc.
The coefficient of thermal expansion of all C6 is also set close to the above value. This is because by doing so, the bending deformation of the head arm 1 when the temperature changes can be minimized.

FPC 6 and head arm 1 of the present invention described above
Although the example in which both the heating member 10a and the temperature sensor 11 are provided has been described above, only one of each may be provided. The effects of each will be described later.

FIG. 6 is a front view of a head arm 1 showing another embodiment, which has one IC chip 12. FIG.

The figure shows an example in which only the heating member 10b is provided within the IC chip 12. Other structures are the same as in FIG. Of course, if it is difficult to provide the heating member 10b inside the IC chip 12, it may be provided inside the FPCG as shown in FIG. It is soldered to the ends of the leads 1iA7, etc. of the FPC6.

Furthermore, the temperature sensor 11 may be provided in the IC chip 12 instead of the heating member 10b, or both may be provided.

Next, the operating principle will be explained in an example in which a plurality of the head arms 1 described above are applied to a servo surface servo type magnetic disk device 14.

FIG. 7 is a cross-sectional view showing the schematic structure of the magnetic disk drive [14], in which a plurality of disks 15 are fixed to a spindle 16 and rotated at high speed by a motor 17.
Information is read and written concentrically on the surface by the magnetic head 3. A carriage 18 moves and positions the magnetic head 3 via the head arm 1. 19 is a control circuit;
20 is a bearing, and 21 is a housing that seals the device.

Since the magnetic disk device 14 is of a servo surface servo type, position information is detected by the servo head 3s located at the center, and the other nine data heads 3a to 31 are positioned accordingly. That is, ten magnetic heads 3 are moved in the same way by one carriage 18. Of course, the position of the servo head 3s does not have to be in the center, and
FIG. 8 is an explanatory diagram in which only the portions necessary for explaining the present invention are extracted from FIG. 7. 3s is a servo head, 15s is a servo disk on which servo information is written, and the servo information is used to control the other five data heads (in the figure) 3c to 3g.
is positioned on a predetermined track on the disk 15.

Here, the temperature of the servo head arm 1b among the plurality of head arms 1 is, for example, the temperature of the servo IC chip 12.
If the temperature rises due to the heat generated by the data head arm 1b, the servo head arm 1b will be heated, and the other data head arm la will be heated.

The amount of thermal expansion (elongation) is larger than that of 1c. For this reason, as shown in FIG. 5, a data head 3c is provided at the tip of the other data head arms la and lc.

3d, 3f, and 3g are off-tracked outward by δ. If this off-track δ is large, the data head will not accurately reach a predetermined track, and the necessary information will not be read or written accurately. In this case, the data head arm is 1g.

If 1c is thermally expanded by the same amount as servo head arm 1b, off-track δ should be prevented.

The arms may be thermally expanded by generating heat in the heating members 10 of the data head arms la and lc. Since the amount of thermal expansion is generally proportional to the temperature, the temperature is detected by the temperature sensor 11 instead of the amount of thermal expansion of each arm 1, and the amount of heating of the heating member 10 is determined according to the output by [1]. Can be reduced. An example of the method will be explained below.

FIG. 9 is a flowchart of a heating control method, which will be explained in correspondence with FIG. 8. Here, a case will be described in which the servo head arm 1b is always at a higher temperature than the other head arms la and lc. First, when the magnetic disk device 14 is activated, heating control is also started. First, the temperature of each head arm 18 to IC is detected by the temperature sensor 11, and the temperature To of the servo head arm 1b is compared with the temperatures Tt and Tz of the other data head arms la and lc, and the temperature difference ΔTi ( ΔT t = T o T i) respectively.

Then, the amount of heating Q is determined according to T1 for each temperature difference.
i is determined, and a current is passed through the heating member 10 to heat it. Δ
The Ti=O data head arm is not heated. This control is repeatedly performed until the magnetic disk device 14 stops.Although this control may be performed continuously, it may also be performed at fixed intervals. Since the temperature change of the head arm 1 is not so rapid, it is considered that it is sufficient to perform the measurement at regular intervals.

Another method is to constantly measure the temperature of the magnetic disk drive 14 or the ambient temperature, find the amount of change (dT), and then shorten the cycle for temperature detection and heating control depending on the magnitude of the value. conduct.

t If it cannot be considered that the temperature of the servo head arm 1b is always higher than the other data head arms la and lc, detect the temperature T of all the head arms 1 and select the highest temperature among them. Based on the head arm,
The temperature difference ΔT with other head arms may be determined, and the heating amount Q of the heating member 10 may be adjusted in accordance with the temperature difference.

When the temperature sensor 11 is a thermocouple or the like, the detected output 7b may be an electromotive force (m V ) or the like. In this case, there is no need to convert it to temperature, and the heating amount Q can be calculated by comparing the output itself.
may be controlled.

If the temperature distribution follows as the temperature of the device increases, such as when starting up a magnetic disk device [14], it is important to investigate in advance how the temperature distribution of each head arm 1 of a certain magnetic disk device 14 follows over time. For example, this should also apply to other magnetic disk devices 14 (models of the same shape). The heating amount Q of the head arm 1 in such a case can be controlled without the temperature sensor 11. That is, in FIG. 1, only the heating member 10 inside the FPCe is provided, and the temperature sensor 11 is not provided. Or
Even if it is provided, it should not be used. Then, the temperature difference ΔT or the direct heating amount Q between each head arm 1 and the reference head arm for each elapsed time is input in advance to the control circuit 19, and the temperature or thermal expansion of each head arm 1 (
Of course, the head arm 1
If the temperature distribution of the disk 15 or the like in addition to the temperature distribution of the disc 15 greatly affects off-track, the amount of heating Q may be determined in advance by taking the resulting off-track into account.

For example, the temperature of the disk 15 or the air temperature between the disks 15 is detected by a separately provided sensor, the amount of thermal expansion of the disk 15 due to the temperature difference from the reference is determined, and the amount is converted to the temperature of the head arm 1. The temperature difference of the head arm 1 may also be taken into consideration.

Alternatively, only the temperature sensor 11 according to the present invention may be provided on the head arm 1 to correct off-track by software (the heating member 10 is not provided), for example, the helad arm shown in FIG. ) is used in the magnetic disk drive 14 as shown in FIG.
a, lb.

Detect the temperature of 1c. Then, the temperature difference ΔT1 between the temperature To of the servo head arm lb (reference arm) and the temperatures Tz and Tz of the other data head arms la and lc is determined, and the heat of each head arm is calculated according to the temperature difference ΔT1. Calculate the amount of expansion (expansion and contraction).

The position of each head arm is corrected by software according to the amount of thermal expansion, and the data head is 30 to 3 g.
This allows the vehicle to reach the official track and prevent off-track. In this case, the temperature of the servo head arm 1b does not need to be higher than the temperature of the other data head arms la and lc, and may be lower. If it is lower, the off-track amount can be corrected in the opposite direction. This will be explained with reference to FIG. 10 using a specific numerical example. FIG. 10 shows an example of the results measured at a certain time, and shows the head arm la.

The temperatures of lb and lc are 21°C and 20°C, respectively.

Assuming that the temperature was 19°C, each arm should be thermally expanded (stretched) in proportion to its temperature. The resulting off-track amount (deviation from the normal track) of each data head 30 to 3g is as shown in FIG. It is assumed that the head arm 1 expands and contracts by 2 μm per 1°C. The data head 3e attached to the servo head arm 1b has an off-track amount of zero. At this time, if you want to read or write data using the data head 3c.

A software correction is made by +2 .mu.m to move the entire carriage 18 toward the outer station of the disk 15.

Further, when it is desired to read or write data using the data head 3g, the entire carriage 18 is moved toward the inner circumferential direction of the disk 15 by making a software correction by -2 μm. The same applies to other data heads. With this configuration, off-track can be reduced even without the heating member 10.

〔Effect of the invention〕

According to the present invention, the temperature or thermal expansion amount of each head arm can be adjusted arbitrarily by the heating amount of the heating member.
If used together with a temperature sensor, the amount of heating can be freely controlled according to the temperature difference. Therefore, in the servo-surface servo type magnetic disk device, the temperature or thermal expansion amount of each head arm can always be controlled to be the same, which reduces off-track.

[Brief explanation of the drawing]

FIG. 1 is a front view showing one embodiment of the magnetic head arm of the present invention, FIG. 2 is a sectional view taken along the line ■-■ of FIG. 1, and FIGS. 3 to 5 are respective examples of other embodiments of the present invention. 6 is a front view showing another embodiment of the magnetic head arm of the present invention, FIG. 7 is a sectional view of a magnetic disk device using the present invention, and FIG. 8 is a sectional view corresponding to FIG. The figure is an enlarged view of the main part of FIG. 7, FIG. 9 is a flowchart showing the control method of the present invention, and FIGS. 10 and 11 are explanatory diagrams showing other effects of the present invention. 1...Arm for head, 2...Arm body, 3...
・Magnetic head, 6...FPC17...Lead wire, 8
... Resin, 1o... Heating member, 11... Temperature sensor, 12... IC chip, 14... Magnetic disk device, 15... Magnetic disk, 18... Carriage,
19...control circuit. Tame 1 Nikusa 3 Otsukura 4 Koryo S Zukazu Otsukankyo

Claims (1)

[Claims] 1. A magnetic head arm equipped with a magnetic head is characterized in that both a temperature sensor and a heating member are provided on the head arm, and the amount of heating of the heating member can be adjusted according to the output of the temperature sensor. Arm for magnetic head.