Laser Magnetic Storage International Company

North American Philips Corporation

Plasmon Lms, Inc.

Philips Electronics North America Corporation

U.S. Philips Corporation

Optical Storage International - U.S.

Philips Electronics N.a. Corporation

Optical Storage International Holland

Optical Storage International

Alliance Storage Technologies, Inc.

Johannes J Verboom

Kurt W Getreuer

David L Schell

David E Lewis

Roger R Bracht

Fred N Wamble

Pierre R Sonneville

Gregory V Hofer

Constant P Baggen

James C McDonald

Cornelis M Van Uijen

Christiaan Steenbergen

Henk A Van Der Put

Erik W Gaal

Jeffrey M Brooke

Keith W Malang

Sonneville, Pierre R

Daniel J Driscoll

Kurt H Getreuer

Gary L Kline

Rodger R Bracht

Kathleen M Connelly

John C Rathe

Cees Van Nimwegen

In order to help maximize the capacity of an optical storage device, and increase the efficiency of addressing, a unique addressing scheme is utilized to provide addressing for an optical storage disk. Importantly, this scheme is compatible with multilayer disks and helps to minimize the potential for errors. In the addressing scheme of the present invention, the storage media is provided with a wobbled groove, which includes addressing information for the media. More specifically, the surface of the media is divided into predetermined sections, or portions, each portion having a selected number of wobble periods. Within these wobble periods, the amplitude of one single wobble period is either reduced or eliminated. The location of this reduced or eliminated wobble signal can then be determined by the readout system of the present invention and utilized to provide addressing information. A look-up table is provided, which includes a corresponding address value for each predetermined wobble period within a defined address frame. By determining the location of the zero or reduced wobble period within the address frame, an address value can be determined by that particular frame period by providing a number of frames adjacent to one another, a specific address is provided. Utilizing this mechanism, robust detection is provided since a differential detection can be easily utilized, and complex modulation techniques are not required.

Amplitude modulated addressing in disk pregroove

For the purpose of providing sector-address information on optical disks, a robust header is realized by utilizing a very simple encoding method that allows asynchronous reading. In order to provide robustness and reliability, the header uses a biphase data format to encode addressing information. The embossed header is further configured with redundant address-fields in a checkerboard pattern between adjacent tracks, in order to provide robustness for media-contamination. Each address-field starts with a unique address-mark and ends with parity-check information to provide reliable error-detection. The entire header can be decoded without the need for a slice-level, thus making it very tolerant to amplitude-variations and DC-offset variations. By combining these characteristics, a header is achieved which is reliable and inherently resistant to failures in providing sector-address information on optical disks.

Robust header configuration and method for reading sector identifiers contained therein

In order to provide a low noise laser beam, a noise reducing feedback network is provided which creates a noise reducing signal and provides that signal to the laser itself. In order to produce the noise reducing signal, the operation of the laser is monitored and the feedback signal is a direct result of this monitoring. Monitoring is accomplished by a fast-forward sense detector, which receives a portion of the laser beam from the operating laser. The output from this fast-forward sense detector is provided to an amplifier which inverts and amplifies the signal. A noise reduction feedback network then receives the amplified signal, appropriately filters this signal, and provides it to the laser itself so as to reduce noise in the laser-beam for the frequency band of importance for reading the recorded data from the optical medium. The noise reduction feedback signal further has sufficiently high impedance so as to not disturb the traditional CW operation of the laser and to avoid interference with the traditional RF modulation of the laser.

Laser driver with noise reduction feedback for optical storage applications

Writing predetermined data pattern to an allocated segment of a disk drive and appropriately reading that one data pattern while varying the read focus characteristics provides for efficient and effective read focus optimization in an optical disk drive. In order to produce helpful data, the read focus offset is varied while reading the different segments of the data pattern, thus producing read out signals with different peak to peak amplitudes. This is compared to data which is obtained by reading the same data pattern while the offset is held constant. Optimization of the read focus offset is carried out and made possible by appropriate analysis of the waveforms produced when reading the predetermined data pattern in these two reading passes. By appropriately tracking the results of the various read focus offsets, an optimum read focus offset can be easily determined.

Read focus optimization for an optical disk drive

A method, circuit and system for selectively and adaptively effecting conditioning of selected samples of a read signal in storage technologies. A circuit embodying the present invention includes sample logic, arithmetic logic and conditioning logic. The sample logic receives samples and provides a main sample and one or more selected neighbor samples. The arithmetic logic compares the main sample to the neighbor samples toward determining satisfaction of selected conditioning criteria. If the selected conditioning criteria are satisfied, the conditioning logic selectively and adaptively effects level conditioning as to the main sample. Further, the level conditioning is combined with a rule compliance system to insure the read data is following the protocol of the data coding format being used. A method embodying the present invention comprises obtaining level conditioning parameters in association with a reference field of the read signal; sampling the read signal at channel bit locations to provide a plurality of samples; selecting a main sample from the plurality of samples; selecting one or more neighbor samples from the plurality of samples, the neighbor samples being disposed at predetermined distances, in channel bits, from the main sample; comparing the main sample to each of the neighbor samples to determine satisfaction of selected conditioning criteria; applying, where the selected conditioning criteria are determined to be satisfied, level conditioning to the main sample, such level conditioning being responsive to the level conditioning parameters.

Enhanced adaptive and selective ISI cancellation for a read channel in storage technologies

An optical recording medium having a number of adjacent tracks for storing digital optical information is provided, such as an optical disc. The tracks extend in a tangential direction, for example, surrounding the center of the disc. Each track is separated by a pitch amount in a radial direction, for example, outward from the center across the tracks. The tracks each have a servo field comprising one tracking mark located on the track in one of four discrete tangential positions A, B, C and D on the track. There is a mark in one of these four positions for every four adjacent tracks on the media. The position of the tracking marks repeat in the same sequence for every four adjacent tracks. For any four such adjacent tracks, the tracks having marks at positions A and B are separated by one track, and tracks having marks at positions C and D are separated by one track.

Tracking method and track format based on quadrature wobble

An optical recording medium having a number of adjacent tracks for storing digital optical information extending in a first direction. The tracks are separated by a pitch amount in a second direction and each track has a servo field comprising at least one synchronization mark and at least one tracking mark in one of at least three positions on the track. The tracking marks of tracks adjacent in the second direction to a first track are in different positions from each other and from the position of the tracking mark on the first track. The track marks extend in the second direction to give rise to cross-talk from the tracking marks of adjacent tracks when the first track is being read.

Tracking method and track format based on radial cross-talk from adjacent tracks

A method, circuit and system for selectively and adaptively effecting level conditioning of selected samples of a read signal in storage technologies. A circuit embodying the present invention includes sample logic, arithmetic logic and conditioning logic. The sample logic receives samples and provides a main sample and one or more selected neighbor samples. The arithmetic logic compares the main sample to the neighbor samples toward determining satisfaction of selected conditioning criteria. If the selected conditioning criteria are satisfied, the conditioning logic selectively and adaptively effects level conditioning as to the main sample. A method embodying the present invention comprises obtaining level conditioning parameters in association with a reference field of the read signal; sampling the read signal at channel bit locations to provide a plurality of samples; selecting a main sample from the plurality of samples; selecting one or more neighbor samples from the plurality of samples, the neighbor samples being disposed at predetermined distances, in channel bits, from the main sample; comparing the main sample to each of the neighbor samples to determine satisfaction of selected conditioning criteria; applying, where the selected conditioning criteria are determined to be satisfied, level conditioning to the main sample, such level conditioning being responsive to the level conditioning parameters.

Adaptive and selective level conditioning of a read channel in storage

A method, circuit and system for canceling inter-symbol interference from samples of a read signal in storage technologies. A circuit embodying the present invention includes sample logic, arithmetic logic and cancellation logic. The sample logic receives samples and provides a main sample and one or more selected neighbor samples. The arithmetic logic compares the main sample to the neighbor samples toward determining satisfaction of selected cancellation criteria. If the selected cancellation criteria are satisfied, the cancellation logic selectively and adaptively effects ISI cancellation as to the main sample. A method embodying the present invention comprises obtaining an ISI cancellation value in association with a reference field of the read signal; sampling the read signal at channel bit locations to provide a plurality of samples; selecting a main sample from the plurality of samples; selecting one or more neighbor samples from the plurality of samples, the neighbor samples being disposed at predetermined distances, in channel bits, from the main sample; comparing the main sample to each of the neighbor samples to determine satisfaction of selected cancellation criteria; applying, where the cancellation criteria are determined to be satisfied, the ISI cancellation value to the main sample.

Adaptive and selective cancellation of inter-symbol interference of a

A method and apparatus for recovering data from an optical read channel provides for improved recording density by tolerating lower phase and amplitude margins. The method includes digitizing a plurality of samples of a first signal, clipping the digitized samples of the first signal, digitally differentiating the clipped digitized samples, determining the relative locations of signal polarity changes, and generating logical values for channel bits based, at least in part, on the relative locations of signal polarity changes. The apparatus for recovering data from an optical read channel includes a signal-level limiter, a digital differentiator coupled to the signal-level limiter, a min/max detector coupled to the digital differentiator, a zero-crossing detector coupled to the digital differentiator, an update signal generator coupled to the zero-crossing detector and the min/max detector, and a channel bit transition generator.

Method and apparatus for maximum likelihood detection

During recording or reading of data in an optical record carrier such as a disc, focus is optimized by adding a focus offset signal to the focus servo error signal. Each frame contains pre-formatted control marks in a servo field, and reference data marks recorded there at a time of data recording. The focus offset signal is optimized by spacing the reference data marks a distance as close as any data marks between which a zero or non-recorded position must be resolved, and taking samples of the optical readout signal as the optical scanning beam passes over or adjacent the reference marks. Four samples are used, taken between the peaks of the signal corresponding to the two reference data marks.

Focus offset optimization for reading optically recorded data

The beginning of a segment within a track of a record carrier, having a plurality of frames in each segment, is identified by detecting the presence of a control mark at a given position near the beginning of a frame, and the absence of a control mark at an adjoining position at which a control mark will be found in all other frames of the segment. The other frames of each segment are free from a mark at the given position. The next bit position containing a mark, after the given position and its adjoining position, is the clock bit position used for bit clock synchronization. An apparatus for reading these marks may include a qualification circuit for evaluating the magnitude of the difference in detector output at the given bit position and the adjoining bit position.

Optical data recorder with segment synchronization marks

The present invention provides a track format for an optical record carrier that is useful in producing a tracking signal with a substantially constant slope at its zero-crossing point for a range of track pitches. The preferred embodiment of track format is also useful in producing a tracking signal that has a substantially constant amplitude over a range of track pitches. The track format, in the preferred embodiment, employs wobbled pits. The sequence in which the wobbled pits occur alternates between adjacent tracks and the offset of the wobbled pits with respect to the center line of a track remain constant regardless of the track pitch. The preferred embodiment of the track format also includes a reference pit that is used to establish the threshold detection level for the read electronics. The location of the reference alternates between tracks to reduce the effect of radial interference on the signal produced using the reference pit and thereby allow an optimal threshold level to be established.

Track format for use with an optical record carrier having a varying

The present invention provide an apparatus and method for verifying that a record carrier has been transformed from a first state to a second state in accordance with the state of a binary information signal being recorded thereon. In operation, the apparatus detects the signal generated by the record carrier during the supposed transformation and compares this signal to the corresponding portion of the binary information signal to determine whether or not the transformation has taken place, i.e., verifies the transformation. The present invention, in one embodiment, is employed in an optical disk system.

Growing community of inventors

Colorado Springs, CO, United States of America

Johannes J Verboom