JPH04351767A - Servo signal write device - Google Patents

Abstract

PURPOSE:To improve the recording precision and to increase the recording speed by detecting the position of a diffraction grating provided together with a head arm as one body by an optical system and controlling a head based on the detection signal of this optial system to write a servo signal and eliminating an excess load to the head and the change of the use condition. CONSTITUTION:A head arm 5 is provided with a diffraction grating 7, and a casing 1 has an aperture part 1a closed with a light-transmissive material to keep the air-tightness. An optical system 10 for position detection has a light source, an optical detector, etc., and detects the position of the head 5A by the reflected light from the grating 7. A servo signal writer 30 and a controller 20 which take in this detection signal control a motor 40 and a voice coil motor 50, and the writer 30 writes the servo signal on a disk 3 by the head 5A. Thus, trouble like application of an excess load to the head 5A and the condition change between recording and use are eliminated, and the recording precision is improved and the recording speed is increased.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a servo signal writing device suitable for head position detection.

0002

[Prior art] In an HDD (hard disk drive),
When a servo signal is written, a head arm is fixed to a moving body provided outside the casing of the HDD, and the movement of the moving body is detected by optical interferometry or the like.

An external control type is generally known in which the position of the head arm is controlled, that is, the writing of servo signals is controlled based on the detection results.

[0004] Also, a mirror is attached to the head arm,
There are also known configurations in which the position of the head is detected by the movement of the mirror, or configurations in which a rotary encoder and an optical system for detecting the head position are provided within the casing of the hard disk drive.

[0005]

[Problems to be Solved by the Invention] However, as hard disks have become smaller, the rigidity of the head has become weaker, so with externally controlled types, the head arm may be deformed or the conditions may vary between use and recording. Because of the difference, there is a limit to the writing accuracy of servo signals.

[0006] Furthermore, in the configuration in which the mirror is attached to the head arm, a load is placed on the head, so the state of the head changes between recording and use, and writing accuracy cannot be improved.
There is also a problem that the resolution becomes low.

Furthermore, in a configuration in which a rotary encoder or the like is provided within the casing, the cost of optical components increases. An object of the present invention is to provide a servo signal writing device that does not change head conditions between recording and use, has extremely high recording accuracy, and has high recording speed.

[0008]

[Means for Solving the Problems] A servo signal writing device according to the present invention, as shown in FIG. 7, an optical system 10 provided outside the casing 1, and servo signal writing means 20, 30 for writing a servo signal to the disk 3 based on a detection signal detected by the optical system 10.

[0009]

In the servo signal writing device according to the present invention, a diffraction grating is provided on a member that moves integrally with the head, and diffracted light diffracted by the diffraction grating is guided to an optical system outside the casing.

[0010] Therefore, there is no inconvenience such as an extra load being applied to the head.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the servo signal writing device according to the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2, a disk 3 and a head arm 5 are built into a casing 1 of a hard disk drive, and the head arm 5 equipped with a head 5A is operated by a voice coil motor 50. The disk 3 is rotated by a motor 40.

[0013] The head arm 5 has a diffraction grating 7.
In addition, an opening 1a is formed in the casing 1, and the opening 1a is closed with a light-transmitting material 2 such as acrylic or glass to maintain airtightness inside the casing 1. It is configured.

The diffraction grating 7 can be of a fixed type or a removable type, and a reflective type or a hologram can also be used.

On the other hand, an optical interference type optical system 10 provided outside the casing 1 includes a light source 10A that emits a laser beam or the like, a mirror 10B that reflects the light from the light source 10A, and a mirror 10B that reflects the light of the light source 10A. BS (beam splitter) 10C, into which the light is incident, and the diffracted light that is irradiated from the BS 10C to the diffraction grating 7 is reflected and sent back to the diffraction grating 7.
The two mirrors 10E and 10D that are irradiated to
It has a photodetector 10F which is separated at 0C and then enters the light.

In this case, when the head arm 5 moves, the diffraction grating 7 also moves together, changing the phase of the diffracted light.
Since the light intensity of the interference light changes sinusoidally, the position of the head 5A is detected by counting it.

The detection signal is transmitted to the servo signal writer 30,
are respectively taken into the controller 20, and the controller 20
The operation of the voice coil motor 50 is controlled by the servo signal writer 30, and the operation of the motor 40 is controlled by the servo signal writer 30, so that a servo signal is written from the head 5A to the disk 3 (servo signal writing means).

Note that if the pitch of the diffraction grating 7 is 2 [μm], the pitch of the signal output of the interference light is 0.5 [μm].
By interpolating, a signal with an even smaller pitch can be obtained.

It is also suitable to use two lasers with slightly different wavelengths as the light source 10A, and by modulating these laser beams, it is also possible to obtain a signal of interference light having a carrier signal. It is.

As explained above, in this embodiment, the head arm 5 is provided with the diffraction grating 7.
The diffracted light is transmitted to the optical system 10 outside the casing 1.
is derived.

[0021]Therefore, there is no inconvenience such as an extra load being applied to the head 5A, and the conditions of the head 5A do not change between recording and use, resulting in extremely high recording accuracy and high recording speed. .

Furthermore, since the optical system 10 is of an optical interference type, the distance between the head 5A and the diffraction grating 7 can be large, so that the assembly workability of the apparatus is improved and the resolution is improved.

[0023]

As understood from the above explanation, in the servo signal writing device according to the present invention, the head is provided with a diffraction grating, and the diffracted light diffracted by the diffraction grating is transmitted to the optical system outside the casing. is derived.

Therefore, there is no inconvenience such as an extra load being applied to the head, and the conditions of the head do not change between recording and use, so recording accuracy is extremely high, and
Recording speed becomes faster.

Furthermore, since the optical system is of an optical interference type, the distance between the head and the diffraction grating can be increased, so that the assembly workability of the apparatus is improved and the resolution can be improved. Furthermore, since the casing can be completely sealed,
Servo signal writing work can be done outside the clean room.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a preferred embodiment of a servo signal writing device according to the present invention.

FIG. 2 is a configuration diagram showing the relationship between a hard disk drive and an optical system.

[Explanation of symbols]

1 Casing 3 Disc 5 Head arm 5A head 7 Diffraction grating 10 Optical system 20 Controller 30 Servo signal writer

Claims (2)

[Claims] 1. A diffraction grating provided on a member movable integrally with a head of a hard disk drive;
A servo signal writing device comprising: an optical system provided outside a casing; and servo signal writing means for writing a servo signal to a disk based on a detection signal detected by the optical system. 2. The servo signal writing device according to claim 1, wherein the optical system is of an optical interference type that interferes with diffracted light diffracted by a diffraction grating.