Method of and apparatus for optically writing, reading and erasing a multi-plane record carrier, and record carrier suitable for said method and apparatus
AssigneeU.S. Philips Corporation
InventorsAntonius H. M. Holtslag, Derk Visser
Life of this patent
Estimating the term…
Abstract
A method of and an apparatus for writing and reading and/or erasing a multilayer record carrier (1) having a guide plane (2) and a plurality of recording planes (4) are described, using a guide beam (5) which cooperates with the guide plane (2) and a scanning beam (6) for at least writing in the recording planes (4). During writing the position of the scanning focus (36) formed by the scanning beam (6) is coupled to the focus (11) of the guide beam (5) which is actively controlled by using guide information which is present in the guide plane (2). During reading the scanning beam (6) is actively controlled by its own servosystem (20-28).
Claims31
A method of optically writing and subsequently reading information in a selected recording plane of an optical record carrier having at least two recording planes substantially parallel to each other and spaced from each other in a longitudinal direction substantially perpendicular to said planes, characterized by comprising:
- providing said optical record carrier with a guide plane parallel to and spaced from said recording planes, said guide plane having markings formed therein defining a track, and
- during writing said method comprises the steps of:
- producing a guide beam and focusing said guide beam to a guide spot in said guide plane determined partly by a common objective system,
- producing a write beam and, simultaneously with said focusing said guide beam, focusing said write beam to a write spot in said selected recording plane, said focusing of said write beam being determined partly by said common objective system,
- generating a first focus error signal responsive to the position of said guide spot in said longitudinal direction, for controlling focusing of the guide beam,
- generating a first tracking error signal, responsive to radiation of a part of said guide beam from said guide plane,
- providing a common adjusting element which is controllable to affect the transverse position of said guide spot with respect to said track,
- controlling the transverse position of said guide spot with respect to said track responsive to said first tracking error signal, by controlling said common adjusting element, and
- causing the transverse position of the write spot with respect to said track to be responsive to said common adjusting element, thereby coupling the transverse position of the write spot in said selected recording plane to said transverse position of said guide spot,
- and during reading and/or erasing, said method comprises the steps of:
- producing a read beam and focusing said read beam to a read spot in said selected recording plane determined partly by said common objective system,
- generating a second focus error signal responsive to the position of said read spot in said longitudinal direction, for controlling focusing of the read beam,
- generating a second tracking error signal, responsive to radiation of a part of said read beam from said read plane, and
- controlling the transverse position of said read spot responsive to said second tracking error signal, at least partly by controlling said common adjusting element.
An apparatus for optically writing and subsequently reading information in a selected recording plane of an optical record carrier having at least two recording planes and a guide plane substantially parallel to each other and spaced from each other in a longitudinal direction substantially perpendicular to said planes, wherein said guide plane has a track formed therein, comprising:
- means, including a common objective system, for producing a write beam and focusing said write beam to a write spot in said selected recording plane,
- characterized in that the apparatus further comprises:
- means, including said common objective system, for producing a guide beam and, simultaneously with said focusing said write beam, focusing said guide beam to a guide spot in said guide plane,
- means for generating a first focus error signal responsive to the position of said guide spot in said longitudinal direction, for controlling focusing of the guide beam,
- means for generating a first tracking error signal, responsive to radiation of a part of said guide beam from said guide plane,
- a common adjusting element which is controllable to affect the transverse position of said guide spot,
- means, operable when said apparatus is in a write mode, and responsive to said first tracking error signal, for controlling said common adjusting element to move the transverse position of said guide spot toward a given transverse position with respect to said track, and
- means for causing the position of the write spot to be responsive to said controlling said common adjusting element, thereby coupling the transverse position of the write spot in said selected recording plane to said transverse position of said guide spot,
- means, including said common objective system, for producing a read beam and focusing said read beam to a read spot in said selected recording plane,
- means for generating a second focus error signal responsive to the position of said read spot in said longitudinal direction, for controlling focusing of the read beam,
- means for generating a second tracking error signal, responsive to radiation of a part of said read beam from said read plane, and
- means, operable when said apparatus is in a read model including said common adjusting element, for controlling the transverse position of said read spot responsive to said second tracking error signal.
A record carrier for use in an apparatus for optically writing and subsequent reading information in a selected one of a plurality of recording planes, said apparatus providing a guide beam and write beam separate from, and simultaneously focusable at a different longitudinal position from, said guide beam for recording information, and means for guiding the transverse position of the write beam responsive to the transverse position of the guide beam,
- said record carrier comprising at least one layer of material for recording information therein in a plurality of recording planes which are substantially parallel to and spaced from each other,
- characterized in that said record carrier further comprises means for defining a single guide plane only,
- said guide plane is substantially parallel to and spaced from all recording planes in said record carrier including said recording planes, and has track guide information formed therein, and
- prior to recording of information in at least one of said recording planes, said at least one of said recording planes is free from guide information.
An apparatus for optically writing and subsequently reading information in a selected recording plane of an optical record carrier having at least two recording planes and a guide plane substantially parallel to each other and spaced from each other in a longitudinal direction substantially perpendicular to said planes, wherein said guide plane has a track formed therein, comprising:
- means, including a common objective system, for producing a scanning beam and focusing said scanning beam to a scan spot in said selected recording plane,
- characterized in that the apparatus further comprises:
- means, including said common objective system, for producing a guide beam and, simultaneously with said focusing said scanning beam, focusing said guide beam to a guide spot in said guide plane,
- means for generating a first focus error signal responsive to the position of said guide spot in said longitudinal direction, for controlling focusing of the guide beam,
- means for generating a first tracking error signal, responsive to radiation of a part of said guide beam from said guide plane,
- a common adjusting element which is controllable to affect the transverse position of said guide spot with respect to said track,
- means, responsive to said first tracking error signal, for controlling said common adjusting element, and thereby controlling the transverse position of said guide spot, and
- means for causing the position of the scan spot to be responsive to said common adjusting element, thereby coupling the transverse position of the scan spot in said selected recording plane to said transverse position of said guide spot, and
- at least one spherical aberration corrector disposed for adjustable correction of spherical aberration in said scanning beam only.
Dependencies are inferred from the claim text.