KR100370758B1 - Method for recording servo track in dynamic head loading drive - Google Patents

Abstract

PURPOSE: A method for recording a servo track in a dynamic head loading drive is provided to improve the accuracy of a position of a servo track by guaranteeing contact between a push pin and an actuator body during servo writing. CONSTITUTION: A head is moved to a home position on a disk. The head is pushed toward an OD(Outer Diameter) to be moved to an interference possible area with a loading ramp. A first ramp test is executed to confirm whether interference is sensed by a contact state between a push pin of a servo track writer and an actuator body. The ramp test is repeated while moving the head toward the OD or an ID(Inner Diameter) as many as preliminarily set track numbers to start fine adjustment according to the sensed result of the interference. The ramp test is repeated while moving the head toward the OD or the ID as many as preliminarily set track numbers to decide a servo track start point according to the sensed result of the interference.

Description

Servo track recording method in dynamic head loading drive

The present invention relates to a dynamic head loading drive, and more particularly to a servo track recording method for controlling the position of the head.

In general, the Dynamic Head Loading Drive (DHL Drive) is a mechanical manufacturing tolerance of the loading ramp, assembly position with the disk edge, and alignment of the head stack. Etc., the position where the interference between the head stack and the loading ramp occurs is changed, thereby changing the range that the drive can use as a data area on the disk. In the conventional DHL drive, the worst case mechanical tolerance is applied at the time of servo writing to position the start point of the servo track lighting (hereinafter track 0) to minimize the possibility of interference between the head and the loading ramp. This method, however, often prevents us from writing a usable data area, and to prevent this, repositioning track 0 outwards reduces the reliability and yield of the drive. Especially in small disk drives with very little available area, avoiding this waste is very important for capacity and reliability. The method developed to solve the above problem is to use an iterative seek process to locate the track 0. This method first establishes a physical reference point and moves from there until a loading ramp is detected. When the head touches the loading ramp again, track 0 is set by moving the head a certain distance from that point. Using this method, the track 0 position can be optimized for each product, thus optimizing storage capacity without affecting reliability or yield. However, if there is interference between the head and the loading ramp here, the loading ramp will push up the flexure and consequently the gramload acting on the slider will be smaller and consequently the flying height will be higher. The higher the flight altitude, the lower the input / output signal quality, and the error occurs when the read / write is performed in that state. Therefore, if a specific pattern is written on each disk surface and read again, it is determined that an interference has occurred if one or more heads do not read the signal properly.

In recent years, sliders for CFH (Constant Flying Height (hereinafter referred to as CFH)), such as TPC sliders and NPAB (Negative Pressure Air Bearing '), are widely used. In the case of heads using these sliders, especially NPAB sliders, the flight altitude remains almost unchanged due to the negative pressure generated by the slider even if the gram load is slightly smaller. Therefore, even if an interference occurs between the head and the loading ramp, the output signal quality of the head does not have a significant effect until the loading ramp increases the force pushing the flexure upwards above the disk. If you continue to move the head in the direction of OD (Outter Diameter), the loading ramp will push up the flexure, and as soon as the pushing force exceeds some threshold, the head will suddenly fall off the disc and out of normal flight and lead / light Becomes impossible. As a result, the DHL drive having the head using NPAB slider has a problem that it is difficult to find the starting point of the interference between the head and the loading ramp by the head signal judgment method due to the change of flight altitude.

Accordingly, an object of the present invention is to improve the positional accuracy of a servo track in a dynamic head loading drive by ensuring contact between a push pin and an actuator body to detect interference between the head and the loading ramp. A servo track recording method is provided.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Many specific details are set forth in the following description in order to provide a more thorough understanding of the present invention. It will be apparent to those skilled in the art that the present invention may be practiced without these specific details. And a detailed description of known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

In general, a servo track writer (hereinafter referred to as STW) uses a mechanical push pin for positioning the drive head when recording a servo track. That is, the STW moves the push pin by calculating an accurate position by using an encoder or a laser interferometer of a stepper motor. At this time, the drive uses a voice coil motor (VCM) to apply a bias force to the head stack assembly in the direction of the push pin, thereby maintaining the contact of the actuator body of the drive with the push pin while maintaining the servo information in the correct position. Record it. To find the starting point of the interference between the head stack and the loading ramp to optimize track 0 position when recording servo tracks on a DHL drive using a slider for constant flight altitude (CFH):

In the first step, the STW first pushes the head to the physical home position. The physical reference point should be set at a sufficient distance so that the head does not touch the loading ramp. In the second step, the STW then moves the head from the physical reference point toward the OD to the interfering area with the loading ramp. The interferable area should then be determined with reference to the worst mechanical manufacturing tolerances. After that, the first ramp test is performed to confirm contact between the push pin of the STW and the actuator body of the drive. For contact confirmation, the STW constitutes a kind of switch as shown in FIG.

Figure 1 shows the configuration of an electrical switch for detecting the interference between the loading lamp and the actuator body according to the present invention. Referring to FIG. 1, a flexible printed circuit (FPC) 4 is a flexible circuit board for connecting a signal read from a head to a lead channel of a drive. The FPC (4) has a chassis ground wire for noise reduction and signal shielding, which is connected to the actuator body (2) by a conductive screw (6). It is connected to the logic power supply (Vcc) through the resistor (8), and the other end of the resistor (R) is connected to the monitor voltage (MV) to check the voltage state of this point to the actuator body (2) and the push pin ( 8) You can see the contact state between them. Hereinafter, the voltage between the push pin 8 and the pull-up resistor R is defined as a monitor voltage (hereinafter referred to as MV).

FIG. 2 shows the electrical equivalent circuit of FIG. 1. In FIG. 1, contact between the actuator body 2 and the push pin 8 is performed by switching the switch SW shown in FIG. 2 to open and close the actuator body. (2) and whether the push pin 8 is in contact. That is, in FIG. 2, if the monitor voltage MV is logic " low " (when the switch is " on "), the contact between the push pin 8 and the actuator body 2 is maintained, and conversely, the monitor voltage MV is logic. The "high" back side (when the switch "off") indicates that the contact between the push pin 8 and the actuator body 2 is broken. If the head touches the loading lamp, the movement to the OD is no longer restricted, and if the push pin 8 moves once more towards the OD, the contact between the gaze pin 8 and the actuator body 2 is broken and the monitor voltage (MV) This logic switches from "low" to "high". Then as a fourth step, if no interference is detected in the first ramp test, i.e. if the monitor voltage (MV) is logic " low, " move the head toward the OD by the first predetermined number of tracks, e. Continue testing. That is, the head movement and ramp test are repeated until the monitor voltage MV switches from logic "low" to "high" or reaches a predetermined number of steps. If the monitor voltage (MV) does not change to "high" within the predetermined number of steps, the lamp test is terminated by finding no loading ramp. On the other hand, if interference is detected during repeated ramp tests, the head is moved to the ID (Inner Diameter) by a second predetermined number of tracks, for example 10 tracks, and fine tuning is started. Then, as the fifth step, if simplicity is detected in the first ramp test, that is, if the monitor voltage MV is a logic "high", the head is moved to the ID by a second predetermined number of tracks and again checks for interference. If interference is still detected, move the head back to the ID for a second predetermined number of tracks and perform a ramp test. This process is repeated until no interference is detected or a certain number of steps is reached. If the monitor voltage (MV) does not turn to logic "low" within a predetermined number of steps, it is regarded as a defective assembly and ends. If no interference is detected during the repeated lamp test, fine adjustment is started. Then, in the sixth step, the STW performs a ramp test while moving the head to the OD by a third predetermined number of tracks (for example, one track) in the fine adjustment. If interference is detected at this time, i.e., if the monitor voltage MV becomes logic " high, " the head is moved to the ID by a fourth predetermined number of tracks (e.g. 20 tracks) and then ramped. If no interference is detected, set it as track 0. The fourth predetermined number of tracks shall be determined in consideration of mechanical tolerances and the like so that track 0 is not interfered by thermal deformation or disc runout during drive operation. Thereafter, as a seventh step, if the interference is detected in the ramp test after moving to the ID by the fourth predetermined track number, the ramp test is performed by moving to the ID by the fifth predetermined track number, for example, one track. If no interference is detected, move the head back to the ID by the fourth predetermined number of tracks and set it as track 0.

As described above, the present invention uses the contact state between the actuator body of the DHL drive and the push pin of the STW as a status signal for detecting the interference between the loading ramp and the head, and finds an interference starting point between the head stack and the loading ramp. By setting the track 0 as the track 0, the track 0 position can be optimized during servo track recording.

Also, during recording of the servo track, the STW calculates and records the track position determined by the push pin while the head maintains the correct position, and continuously monitors the contact state between the actuator of the drive and the push pin of the STW. It is advantageous to improve the quality of servo recording by identifying the cause and taking appropriate measures and re-recording the track.

Meanwhile, in the embodiment of the present invention, a slider for CFH is illustrated, but the present invention may be applied to a slider using a conventional two-rail type floating surface without any modification.

1 is a layout view of an electrical switch for detecting interference between a loading ramp and an actuator body according to the invention.

2 is an electrical equivalent circuit of FIG.

Claims (2)

In the dynamic head loading drive, the servo track writer servos on the disc by using the electrical contact state between the actuator body of the dynamic head loading drive and the push pin of the servo track writer as a status signal for detecting interference between the loading ramp and the head. In the method for recording a track, Moving the head to a physical reference point on the disc; A second step of pushing the head from the physical reference point toward an outer diameter (OD) on the disc to an interferenceable area with the loading ramp; Performing a first ramp test to determine whether interference is detected by a contact state between the push pin of the servo tracker and the actuator body; If the interference is not detected in the first ramp test, the lamp test is repeatedly performed while moving the head toward the OD by the first predetermined number of tracks, and if the interference is detected within the predetermined number of steps, the head is stopped. A fourth step of moving to an ID (Inner Diameter) on the disc by a predetermined number of tracks and starting fine adjustment; When the interference is detected in the first ramp test, the lamp test is repeatedly performed while moving the head to the ID by the second predetermined number of tracks. When the interference is not detected within the predetermined number of steps, the fine adjustment is performed. Start with the fifth step, In the fine adjustment of the fourth and fifth steps, the lamp test is repeatedly performed while moving the head to the OD by the third predetermined track number, and when the interference is detected, the head is moved by the fourth predetermined track number. Step 6 to set the start point of servo track lighting if the interference is not detected by performing a ramp test after In the sixth step, if the interference is not detected in the ramp test performed after moving the head to the ID by the fourth predetermined track number, the lamp test is performed by moving the head to the ID by the fifth predetermined track number. And repeatedly performing a seventh step of moving the head back to the ID by the number of tracks defined by the fourth mirror if the interference is not detected, and then designating the place as the starting point of the servo track writing. Servo track recording method of loading drive. The method of claim 1, Terminating the lamp test if no interference is detected within the predetermined number of steps in the fourth step; And if the interference is continuously detected until reaching the predetermined number of steps in the fifth step, ending the track track of the dynamic head loading drive.