Tracking Property of Adjacent Track Servo System for Optical Disk Drives

The size of digital content has been on the increasing in recent times, and this has been led to the need for correspondingly scaling up the capacity of digital storage media. Therefore, a high-precision focusing and tracking control system are required for an optical disk. A pickup system for optical disks operates in the horizontal and vertical directions for tracking and focusing, respectively. Thus, this paper proposes a new single-rate two-dimensional feedforward control system, which is the concurrent control of focusing and tracking. The feedforward controller is based on a zero phase error tracking (ZPET) control. Experimental results show the effectiveness of the proposed control system.

“…The feedback controllers for focusing and tracking, C f (z) and C t (z), respectively, are as expressed in Eqs. ( 13) and (14). Feedback controller C(z) is shared by C f (z) and C t (z).…”

Section: Design Of Feedback Controllermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Single-rate two-dimensional feedforward control system for optical disk systems in consideration of the phase delay

Ohashi¹,

Yoshida²,

Ohishi³

et al. 2015

“…Since data are recorded on the basis of the recording spot, such a shift can cause previously recorded data marks to be overwritten. One solution to this problem is the adjacent track servo system with linear positioning method developed by Urakawa et al [19][20][21][22][23] However, the need to form a particular pit structure on the servo layer to maintain a continuous linear position on the groove-less disk could increase the disk fabrication cost. An alternative is the advanced radial position control system developed by Tanaka et al, [24][25][26][27][28] but its use of feed-forward control it is not sufficiently robust against shock and vibration.…”

Section: Introductionmentioning

confidence: 99%

Decoupled direct tracking control system based on use of a virtual track for multilayer disk with a separate guide layer

Tanaka

Ogata

Imagawa

2015

We developed a decoupled direct tracking control system for multilayer optical disk that uses a separate guide layer. Data marks are recorded on a recording layer immediately above the guide layer by using two spatially separated spots with different wavelengths. Accurate data mark recording requires that the relative positions of the corresponding spots on the recording layer and guide layer are maintained. However, a disk tilt can shift their relative positions and cause previously recorded data marks to be overwritten. Additionally, a two-input/two-output control system is susceptible to mutual interference phenomenon between the two outputs, which can destabilize tracking control. A tracking control system based on use of data marks previously recorded as a virtual track has been developed that prevents spot shifting and mutual interference even if the disk tilt reaches 0.7°, thereby preventing overwriting.

High Precision Tracking Control based on Pseudo-Inverse Feedforward Control System for Next-Generation Optical Disks

Ogata¹,

Nakazaki²,

Sakimura³

et al. 2012

The crossover function for the specific heat of a disordered material is constructed to order E by solving the renormalisation group equations for the m n model (m + 0, n > 1).From this an effective exponent is obtained which provides a local measure of the degree of singularity of the specific heat in the critical region. It is seen that as the critical region is approached from above the critical temperature the effective exponent behaves initially as if no disorder were present. But as the critical temperature is more closely approached the effective exponent crosses over to the value predicted for the disordered material.