JPS6232548B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a precision positioning device, such as a magnetic head positioning mechanism for a magnetic disk storage device.

As an example of a precision positioning mechanism, a magnetic head positioning mechanism used in a magnetic disk storage device will be described.

In recent years, the development of magnetic disk devices for computer systems has been remarkable, and companies are striving to improve reliability, increase capacity, and reduce size and cost. Office computers in particular require compact, low-cost, large-capacity, and highly reliable magnetic disk drives. Therefore, the challenge for small magnetic disk devices is how to increase the recording density while maintaining high reliability. If high recording density can be achieved, the storage capacity can be increased without increasing the device size, which would be advantageous as a magnetic disk for office computers.

In order to increase the recording density, it is important to increase the number of information tracks per magnetic disk (improvement in track density) and to increase the amount of information per track (improvement in bit density). The upper limit of bit density is determined by the characteristics of the magnetic disk coating and magnetic head, and current technology has a limit of 12,000 BPI (BIT PER).
INCH) is the highest level. Also, the track density is 500 TPI (TRACK
PER INCH), for a low-cost small disk device that uses a step motor and does not have a servo function.
The highest value was 100-200 TPI. Therefore, in the latter small disk device, the key point is how to improve the track density in an inexpensive manner.

The reason why the upper limit of the track density is suppressed is due to the relative positional error between the magnetic head and the information track, and this positional error is caused by the combination of various factors shown below. The main causes include (1) thermal expansion errors caused by differences in linear expansion coefficients of each member that makes up the positioning system, (2) angular accuracy of the step motor, and (3) angular errors due to input fluctuations of the step motor. , especially (1)
Thermal expansion error is an unavoidable problem in open-loop systems without servo functions, and is the primary reason why TPI cannot be improved. Naturally, if the positioning error exceeds the expected value due to these various factors, it will result in an irrecoverable error, resulting in a serious failure of the magnetic disk device.

An object of the present invention is to provide an open-loop positioning device with a mechanism that can automatically correct thermal expansion errors caused by environmental temperature changes and differences in linear expansion coefficients of each component, and to provide surplus power against temperature changes. It is an object of the present invention to provide a precision positioning device that is durable and has good positioning accuracy.

Using a bimetal that reacts with temperature, a torque that automatically varies according to environmental temperature changes is applied to the step motor output shaft, and the positioning position can be adjusted by using the fact that the step motor's rest position changes with external torque. Perform correction automatically.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. A pulley 25 is fixed to the output shaft of a step motor 28 by a screw 23 and a washer 24, and a steel belt 18 is further fixed to the pulley 25 by a plate 26 and a screw 27. The other end of the steel belt 18 is connected to another pulley 17 rotatably installed by a shaft 15 and a plate 16.
The spring hooks 51 and 53 are wrapped around the screw 5.
2, and a spring 54 is installed with a certain tension between the tip of the bimetal 55 and the spring hook 51. Also, the plate 16 has screws 1
3 is fixed to the pulley stand 12, and the pulley stand 12
is fixed to the base 50 by screws 14. Further, the bimetal 55 is fixed to a bimetal stand 58 with a screw 56, and the bimetal stand 58 is fixed to a bimetal stand 58 with a screw 56.
7 is fixed to the base 50. On the other hand, the magnetic head moving body (carriage) 40 includes a gimbal 33.
The magnetic head 32 is held by a head loading spring 34 and is pressed onto the surface of the rotating magnetic disk 1. magnetic head 32
floats stably on the magnetic disk 1 with a gap of about 0.5 μm due to the air viscous flow generated on the disk surface. The head lead wire 35 is the relay terminal 3
6 to the lead wire 38, and the main lead wire 3
Magnetic recording is performed through 8. This head moving body 4
0 is guided by two guide bars 6 and 9, and a plate 21 and a screw 22 are attached to one side of the steel belt 18.
It is installed by. In Figures 2 and 3, the environmental temperature becomes higher and lower than normal temperature, the bimetal 55 operates, the length of the spring 54 changes, and the external torque applied to the step motor pulley 25 becomes t1 and t3, respectively. Indicates the condition. FIG. 4 is a characteristic diagram showing the external force torque and static angular position of the step motor 28, where t1, t2, and t3 indicate the external force torque at high temperature, normal temperature, and low temperature, respectively. θ1, θ2, θ3
indicate their resting positions. As is clear from Figures 2 to 4, when the environment changes from normal temperature to high and low temperatures, the bimetal 55 operates and the external force torque t2
(at normal temperature) to t1 (at high temperature) or t3 (at low temperature), and according to the characteristics shown in Figure 4, the resting position changes to θ1 (at high temperature) and θ3 (at low temperature) and is automatically corrected. be done. It goes without saying that in this embodiment, positioning errors due to temperature occur on the outer circumferential side of the disk when the temperature is high, and on the inner circumferential side when the temperature is low. It is also clear that the amount of correction is determined from the characteristic curve shown in FIG. 4, the amount of change in the bimetal 55, and the spring constant of the spring 54.

According to the present invention, it is possible to correct positioning errors caused by temperature changes, which is the biggest drawback of the open loop method, and it has sufficient resistance to temperature changes.
Moreover, a precision positioning device with good positioning accuracy can be obtained. Also, because the invention is very simple, it is reliable and inexpensive.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing one embodiment of the present invention;
3 is a plan view showing the state when the environmental temperature changes, and FIG. 4 is a characteristic diagram showing the relationship between the rest position of the step motor and the external force torque. DESCRIPTION OF SYMBOLS 1...Magnetic disk, 6...Guide bar, 7...Screw, 8...Base support, 9...Guide bar, 10...Screw, 11...Base support, 12...Pulley stand, 13...
Screw, 14...Screw, 15...Shaft, 16...Plate, 17...Pulley, 18...Steel belt, 2
1...Plate, 22...Screw, 23...Screw, 24...
Washer, 25...Pulley, 26...Plate, 27
...Screw, 28...Step motor, 29...Screw, 3
0... Guide bar base, 31... Screw, 32... Magnetic head, 33... Gimbal, 34... Head loading spring, 35... Magnetic head lead wire, 36... Relay terminal, 37... Lead wire clamp, 38... Lead wire, 39... Characteristic curve, 40... Magnetic head moving body, 41... Step motor lead wire, 50... Base, 51... Spring hook, 52... Screw, 53... Spring hook, 54... Spring, 55... Bimetal, 56...
Screw, 57...screw, 58...bimetal stand.

Claims (1)

[Claims] 1. In a positioning mechanism using a step motor as a drive source, one end of a belt is fixed to a pulley directly connected to the output shaft of the step motor or directly to the output shaft, and the other end of the belt is fixed via a spring,
It is fixed to a bimetal member, and a carriage on which a positioning object is mounted is fixed near the center of the belt, and the slideable carriage is moved/positioned according to the rotation/stop of the step motor, and the structure is such that the carriage is moved/positioned according to the rotation/stop of the step motor. By deforming the bimetal according to the change, the tension of the spring changes, that is, the external force torque of the step motor is changed, and positioning errors due to temperature caused by differences in linear expansion coefficients of each member are automatically corrected. Features a positioning mechanism.