KR100412058B1 - Apparatus for removing residual current generated from voice coil motor and removing method thereof - Google Patents

Abstract

PURPOSE: An apparatus for removing residual current generated from a voice coil motor and a removing method thereof are provided to compensate an offset value of a head by removing the residual current from the voice coil motor. CONSTITUTION: An apparatus for removing residual current generated from a voice coil motor includes a comparator, an A/D converter, and a controller. The comparator is used for comparing a reference voltage with a voltage difference between voltages applied to both ends of the voice coil motor. The A/D converter(54) is used for converting an output value of the comparator to the digital data. The controller(32) is used for removing the residual current from the voice coil motor by changing the amount of current applied to both ends of the voice coil motor on the basis of a difference between an output value of the A/D converter and the reference voltage when the output value of the A/D converter is different from the reference voltage.

Description

Residual current removing device generated in voice coil motor and its method

The present invention relates to the control of a voice coil motor (hereinafter referred to as a VCM) of a disc drive recording apparatus. In particular, the present invention can eliminate residual current generated in a VCM coil when a direction of a current applied to the VCM is changed. An apparatus and a method thereof are provided.

In a typical disc drive recording apparatus, a disc is divided into tracks concentrically from the center of the disc, and each track is divided into a servo area in which servo information for servo control is recorded and a data area in which user data is recorded. To read or write data at the target position on the disc described above, move the head to the target position (this is commonly referred to as track search) and then place the head on the center line of the target position (this is the normal track). In this case, the servo control method of the head drive unit in the disc drive recording apparatus performs velocity control until the target position is reached, and on-track (on the target position) is performed. position control is performed. Hereinafter, a block diagram related to servo control of a general disk drive recording will be described to help understand the present invention.

Fig. 1 shows a block diagram of a general disc drive recording apparatus and shows an example of a hard disc drive having two discs 20 and four heads 22 corresponding thereto. Referring to FIG. 1, the disks 20 are typically stacked and mounted on the drive shaft of the spindle motor 44, and are designed such that one head 22 corresponds to each disk surface. The head 22 is located on the surface of the disk 20 and is mounted to a vertically extending arm 24 of the arm assembly of the VCM 38. The preamplifier 26 preamplifies the signal picked up by one of the heads 22 during data read and applies the analog read signal to the read / write channel circuit 28. During data write, encoded write data applied from the read / write channel circuit 28 is written onto the disc 20 through the switched selected head 22. At this time, the preamplifier 26 switches to select one of the heads 22 under the control of a disk data controller (DDC) 46. The read / write channel circuit 28 decodes the read signal path applied from the preamplifier 26 to generate read data RDATA, and encodes the write data WDATA applied from the disk data controller 46 to the preamplifier 26. Is authorized. The read / write channel circuit 28 also demodulates the head position information which is a part of the servo information written on the disk 20 to generate a position error signal (PES). The PES generated from the read / write channel circuit 28 is applied to the A / D converter 30, and the A / D converter 30 converts the applied PES into a digital step value corresponding to its level so as to provide a microcontroller ( 32). The disk data controller 46 writes the data received from the host computer onto the disk 20 through the read / write channel circuit 28 and the preamplifier 26 or the data read from the disk 20 to the host computer. Send. The disk data controller 46 also interfaces the communication between the host computer and the microcontroller 32. On the other hand, the microcontroller 32 controls the disc data controller 46 in response to the data read / write command received from the host computer and controls track search and track following. At this time, the microcontroller 32 controls the track tracking by using the PES value input from the A / D converter 30, and responds to various servo control signals output from a gate array (not shown). Perform control. The D / A converter 34 converts a control value for position control of the heads 22 generated from the microcontroller 32 into an analog signal and outputs the analog signal. The VCM driver 26 generates a current I (t) for driving the actuator by a signal applied from the D / A converter 24 and applies it to the VCM 38. The VCM 38 located at the other side of the actuator having the heads 22 attached to one side may horizontally move the heads 22 on the disk 20 in correspondence with the direction and the level of the current input from the VCM driver 36. Move it. The motor controller 40 controls the spindle motor driver 42 according to a control value for rotation control of the disks 20 generated from the microcontroller 32. The spindle motor driver 42 rotates the disks 20 by driving the spindle motor 44 under the control of the motor controller 40. The buffer memory 48 connected to the disk data controller 46 temporarily stores data transferred between the disk 20 and the host computer under the control of the disk data controller 46.

In the hard disk drive having the above-described configuration, the head 22 must be positioned on the target track in order to read data written on the disk 20. To this end, the microcontroller 32 places the head 22 on the target track by applying a predetermined level of forward or reverse current to the coil of the VCM 38 located on one side of the actuator. At this time, the forward current represents a current applied to continuously move the head 22 in the direction in which the current head 22 is moving, and the reverse current represents a VCM (for moving the moving head 22 in the reverse direction). The current applied to 38) is shown. If the direction of the current applied to the VCM 38 is changed in order to move the head 22 moving inwardly on the disk 22 outwardly or to move the head 22 moving outwardly inwardly, the coil ( Due to the electrical characteristics of the coil, the residual current component is generated in the VCM 38. This residual current component is added to the current applied to the VCM 38 when the head 22 changes direction to over move the head 22 on the target track. That is, in the conventional disk drive recording apparatus, when the direction of the current applied to the VCM 38 is changed, there is a problem that the head 22 is offset on the target track due to the generation of the residual current component due to the electrical characteristics of the coil. .

Accordingly, an object of the present invention is to provide an apparatus and method for removing residual current components of a coil generated when the direction of current applied to the voice coil motor of the disc drive recording apparatus is switched.

1 is a block diagram of a typical hard disk drive.

Figure 2 is a circuit diagram of a residual current erasing device according to an embodiment of the present invention.

3 is a control flow diagram of a microcontroller 32 according to an embodiment of the present invention.

Hereinafter, an operation according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the following description and the annexed drawings, like elements have been given the same reference numerals and many specific details, such as current direction and specific processing flow, etc., are shown to provide a more general understanding of the invention. It will be apparent to those skilled in the art that the present invention may be practiced without these specific details. In the following description, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

2 is a circuit diagram of a conventional servo control block diagram 50 in which a residual current cancellation device according to an embodiment of the present invention is connected. Referring to FIG. 2, the residual current canceller according to an exemplary embodiment of the present invention compares a difference between current levels applied to the VCM 38 from both output terminals VCM + and VCM− of the VCM driver 36 to a reference voltage. A comparator 52 for outputting the value, an A / D converter 54 for digitally converting an analog type comparison value input from the output of the comparator 52, and one input end of the VCM 38; It is composed of Schottky diodes SD1 and SD2, which are respectively connected between grounds and cut off the transient current caused by the residual current of the VCM 38 coil.

3 is a flowchart illustrating a control flow of the microcontroller 32 according to an exemplary embodiment of the present invention. Referring to FIGS. 2 and 3, when the direction of the current applied to the VCM 38 is changed, the coil L is changed. The operation of the microcontroller 32 and the residual current scavenging device for removing the residual current component generated in the following will be described in detail. Meanwhile, in the following description, it is assumed that the current head 22 is located at the center track of the data zone. First, in step 56, the microcontroller 32 checks whether there is a data read / write command from the host computer. If a data read or data write command is received, the microcontroller 32 proceeds to step 58 to check whether track search is necessary. If the track search is necessary as a result of the inspection, the microcontroller 32 proceeds to step 60 and outputs a control value U for moving the head 22 on the target track through the P2 terminal. By the control value U output in step 60, a predetermined level of current is applied to the VCM 38 coil L from the output terminals VCM + and VCM- of the VCM driver 36, and at this time, the VCM 38 coil L The current applied to is defined as forward current. On the other hand, the comparator 52 measures the magnitude of the voltage difference (VA-VB) between the both ends of the coil (L) by the forward current through the VA and VB terminals. And the result is output to the A / D converter 54. The A / D converter 54 converts the input analogue comparison value into digital data and outputs it to the P1 terminal of the microcontroller 32 so that the microcontroller 32 receives the comparison value in step 62. The microcontroller 32 then proceeds to step 64 to check whether reverse current application is required. The inspection method can be obtained by subtracting the position of the current track from the target track. If it is necessary to apply the reverse current as a result of the test, the microcontroller 32 proceeds to step 66 and compensates the residual current component (extra voltage) of the coil L generated due to the application of the reverse current, and proceeds to step 68. do. The compensation method of the residual current component VE is greater than or equal to the reference voltage Vref by adding or subtracting the residual current component VE to a code value applied to the coil L of the VCM 38 when reverse current is applied. It is not to be small. After that, the microcontroller 32 outputs the control value U 'compensated in step 68, and then returns to step 62 and repeats steps 62 to 68 described above to change the direction of the current applied to the VCM 38. Residual current components of the generated coil (L) can be removed.

As described above, the present invention has the advantage of compensating the offset value of the head by removing the residual current component generated in the coil when the direction of the current applied to the voice coil motor is switched.

Claims (3)

A disk drive recording apparatus comprising a voice coil motor, A comparator for comparing a difference between voltages applied across the voice coil motor with a reference voltage; An A / D converter for converting and outputting the output value of the comparator into digital data; And a controller for removing the residual current of the voice coil motor by changing the amount of current applied to both ends of the voice coil motor by using the difference value when the output value of the A / D converter is different from the reference voltage. Residual current removal device of a disk drive recording device. The Schottky diode of claim 1, wherein the schottky diode is connected between the voice coil motor input terminal and the ground to cut off the transient current caused by the residual current component generated in the coil when the direction of the current applied to the voice coil motor is changed. Residual current removal device characterized in that it further comprises. In the residual current removal method of the disc drive recording apparatus provided with a voice coil motor, When the data read / write command is received from the host computer, checking whether or not the track search is performed; Outputting a control value for moving the head when a track search is necessary as a result of the inspection; Applying a current to a coil of the voice coil motor based on the control value; When the direction of the current applied to both ends of the voice coil motor is changed, comparing the voltage difference between the both ends of the voice coil motor with a preset reference voltage and changing the control value using the difference value. Residual current removal method.