Patent Application
20080285396
This invention is generally in the field of optical memory devices, and relates to a method and apparatus of formatting three dimensional optical information storage carriers used for recording, reading, and erasing of information.
Optical storage is one of the most popular information storage methods. Some optical discs in addition to information written on them have so called “formatting” or “servo” marks, used for positioning, tracking, and writing/erasing user data and other system information.
In conventional optical discs, servo marks are embossed marks or symbols having a certain pattern that indicate the coordinates of the optical pick-up head. Knowledge of these coordinates allows synchronized information recording or reading.
WO 2005/015552, to the same applicant as the present application, discloses a formatter for inscription of marks onto a 3D translucent optical medium to enable recording and retrieval of information from the medium. The formatter includes a clamping mechanism to hold the media, and at least one optical unit calibrated to focus at least one diffraction limited spot within the medium at a respective depth therein. At least one light source is optimized for the inscription of marks, and at least one actuator moves the spot relative to the medium.
According to some standards, formatting marks are located on spiral tracks beginning at the largest recordable dimension of an optical information carrier and ending at the smallest recordable dimension or vise versa. Formatting marks are recorded by scanning an optical pick-up or recording unit (OPU) along such a spiral track. A rate determining factor for formatting is the time it takes to bring the medium to be recorded to proper location relative to the recording elements. Thus, according to the conventional technique, formatting is a time consuming process, since it takes a long time to move from one location were formatting mark(s) is/are recorded to a second location in which formatting marks are recorded.
There is a need in the art to facilitate formatting a three dimensional optical information carrier by reducing the required formatting time.
The main idea of the present invention is associated with the following. Formatting is especially important for multilayer storage media, such as two-photon media where information or data is recorded on hundreds of layers. The accuracy of formatting does not allow using one formatting layer for all data layers. Accordingly, such media should be supplied to the user with more than one formatted layer. As indicated above, the conventional formatting process is time consuming. Considering a 3D information carrier requiring multiple formatting layers, the use of such a conventional technique will make the formatting process even more time consuming.
Two-photon or other volumetric (3D) multilayer storage media may be monolithic, or may be composed of a number attached to each other plates. The monolithic media plate/body may have one embossed formatting layer only. Some of the plates of which the media is assembled may have an embossed formatting layer. Nevertheless, these formatting layers may not be sufficient for data recording, and additional optically recorded formatting layers have to be produced in the media. The embossed layer in such cases serves as a reference layer for subsequent optical recording of additional formatting layers.
The present invention solves the above problem by providing a novel method and apparatus for use in formatting at least one three-dimensional optical information carrier. The invention provides for fast and accurate formation of the formatting marks, enabling also concurrent formatting of multiple carriers. The invention provides for successively producing a sequence of groups of the formatting marks in the same carrier using multiple optical recording units.
According to the present invention, the formatting marks are recorded in an interleaved order, rather than in a sequential one. By this, delays of the recording of formatting marks (which is inherent in sequential recording) could be significantly reduced. The formatting marks may be configured as regular marks, oblong marks, and/or oblong and tilted marks, and may be of different controlled sizes and shapes.
It should be understood that the term “interleaved order” signifies an order of the formatting marks creation different from a sequential order in which these marks are to be addressed (scanned) when reading/recording information in the carrier. The marks that indicate a track may be of different types where each mark type forms a track indicating sub-sequence that during track reading is retrieved in sequence (with respect to itself) and in parallel to the other sub-sequences. Thus, the technique of the present invention, instead of using sequential creation of the formatting marks while scanning a laser beam along multiple spiral tracks, utilizes various types of interleaved formatting, including axial formatting (creation of marks at different depths in the carrier by fast refocusing a recording laser beam along the optical axis of an optical recording unit) and/or radial formatting (by fast reciprocating movement of a laser beam along the radii in the carrier and stepwise rotation of the carrier), or a combination of axial formatting and the scanning spot method.
The formatting marks are preferably recorded about nominal positions of nodes of a three-dimensional grid (lattice) formed by intersection between equidistantly spaced spiral (cylindrical) tracks, equiangular spaced radial planes or cylindrical sections (formed by the movement of the recording unit(s) along arcs) and recording planes (virtual layers) substantially orthogonal to the radial planes. The axes of such a grid (lattice) correspond to the radial mark position, angular mark position, and position of the mark in the carrier depth (or axial direction). The marks may be evenly spaced along each of the radii; the radii may bear an equal amount of the marks; more than one mark may be produced in the vicinity of the grid node.
Here, the expression “about nominal position of nodes” signifies that the formatting marks are located in the vicinity of said nodes, namely, the formatting marks' arrangement corresponds to the arrangement of nodes of said grid, while it should be noted that each node may contain in its vicinity a single formatting mark or a few formatting marks. The lattice structure of the grid of nodes is equivalently evident in the lattice structure of the formatting marks. The lattice structure is kept in a locality, whose size is proportional to the formatting accuracy. Also, it should be noted that the term “recording plane” used herein signifies a substantially planar surface (which may not be exactly planar, since noise or disturbance might cause the recording surface to be a slightly distorted plane).
The technique of the present invention provides for concurrently or sequentially recording a group of formatting marks, namely for recording the entire set of formatting marks by successively recording the groups of marks. This can be implemented using a single optical recording unit or multiple such units (generally a single recording beam or multiple beams).
It should also be noted that grid offsets (shifts) between groups or subgroups of layers or annular zones may intentionally be introduced resulting in respective lattice offsets, thereby differentiating between groups or subgroups of formatting marks. Controlled offsets may be predetermined or pseudo random offsets. Different types of grids may be interwoven in the same carrier. One of the advantages of such mixing is to differentiate between groups or subgroups of layers or annular zones.
The technique of the present invention allows the formatting process to have inherent limits such as limited working distance of a lens system of an optical recording unit, limited movement of the lens actuator at the required accuracy, or limited ability to accurately couple a plurality of optical recording units to record accurately about the lattice nodes. Any such limit makes it advantageous to divide the formatting infrastructure of the formatted medium into a number of groups and each group is independent in terms of formatting and formatting accuracies. This results in an optical storage medium that is formatted more efficiently and is having increased accuracy. The optical storage medium comprising a division into subgroups that are independent in terms formatting and the ability to track the formatting patterns therein.
Thus, according to one broad aspect of the invention, there is provided a method of formatting at least one optical information carrier to create a plurality of formatting marks that are to be sequentially addressed when reading recording information in the carrier, the method comprising recording the plurality of formatting marks within the carrier volume in an interleaved order, thereby reducing delays in recording locally adjacent formatting marks thus reducing the entire carrier formatting time.
According to another broad aspect of the invention, there is provided a method of formatting at least one optical information carrier to create a plurality of formatting marks a monolithic volume of the carrier that are to be sequentially addressed when reading recording information in the carrier, the method comprising: controlling formatting accuracy per predefined sub-volumes of the monolithic volume of the carrier.
According to yet another broad aspect of the invention, there is provided a 3D information carrier formed by one or more monolithic plates, the carrier having a format formed by a three dimensional grid that has localized lattice-like correlation between formatting marks. The grid can have offsets, and different types of lattices can be interwoven.
According to another broad aspect of the invention, there is provided a 3D carrier formed by one or more monolithic plates, the carrier having a format formed by groupings of a certain grid of formatting marks into independent sub-volumes.
According to yet another broad aspect of the invention, there is provided a method of formatting at least one optical information carrier to create a plurality of formatting marks that are to be sequentially addressed when reading recording information in the carrier, the method comprising arranging the formatting marks about nominal positions of nodes of a three dimensional grid configured with local substantially lattice like structure correlation.
According to yet another broad aspect of the invention, there is provided a method of formatting at least one optical information carrier, the method comprising recording a plurality of formatting marks within the carrier volume of a substantially annular cross-section, said formatting marks being arranged about nominal positions of nodes of a grid formed by intersection between equidistantly spaced cylindrical spiral tracks, equiangular spaced radial planes, and recording planes substantially orthogonal to the radial planes.
In some embodiments of the invention, the recording of formatting marks may be performed by linear reciprocating movement and rotational movement of the three-dimensional information carrier, and appropriately synchronized activation of at least one optical recording (pick-up) unit to focus a recording beam onto the carrier.
In some other embodiments of the invention, the recording of formatting marks is performed by a fast reciprocating movement of an optical recording unit along radii of the carrier (while appropriately timely producing a recording light beam) and a stepwise rotation of the carrier.
In further embodiments of the invention, the recording of formatting marks comprises rotating the carrier around its rotation axis, displacing the light beam (e.g. by moving the optical unit and/or by deflection) along a spiral track, continuously refocusing the light beam in axial direction and scanning a recording spot along the track in a direction orthogonal to the axial direction, and controllably activating the light source (laser), such that the marks are recorded on a plurality of adjacent tracks located at different layers (depth) of the carrier. Multiple laser beams (e.g. multiple optical units) may be used for recording the marks in the same carrier, such that each laser beam records marks along a segment of the spiral track and/or a depth region different from that of the other beams.
In yet other embodiments of the invention, the recording of formatting marks is performed by synchronized rotation of a plurality of the optical information carriers and rotation of the plurality of optical recording units all around a common rotation axis, and rotation of the optical information carriers around their rotation axis substantially parallel to said common rotation axis.
According to another broad aspect of the invention, there is provided a method of formatting an optical information carrier, the method comprising: providing synchronized rotation of an optical information carrier around its rotation axis, rotation of an optical recording unit around a central axis spaced-apart and substantially parallel to said rotation axis of the carrier, and rotation of the optical information carrier around said central axis, and providing controlled activation of the optical recording unit, thereby producing a set of formatting marks within the carrier volume of a substantially annular cross-section arranged in a constant angular velocity formatting pattern in the carrier.
According to yet another aspect of the invention, there is provided a method of formatting an optical information carrier, the method comprising: providing at least one information carrier and at least one optical recording unit; rotating said at least one carrier in a stepwise manner around its rotation axis and moving said at least one optical recording unit along a radius of the carrier; continuously refocusing a light beam produced by the optical recording unit in axial direction of the optical recording unit; and controllably activating a light source, such that the optical recording unit records a group of formatting marks at different layers in the carrier within the carrier volume of a substantially annular cross-section.
According to yet another aspect of the invention, there is provided a method of formatting an optical information carrier, the method comprising: providing at least one information carrier and at least one optical recording unit; rotating the carrier around its rotation axis and moving the optical recording unit along a spiral track; continuously refocusing a light beam produced by the optical recording unit in axial direction of the optical recording unit; and timely activating a light source, such that the optical recording unit records a group of formatting marks at different layers in the carrier within the carrier volume of a substantially annular cross-section.
According to yet another aspect of the invention, there is provided a method of formatting an optical information carrier, the method comprising: providing at least one information carrier and at least one optical recording unit; rotating the carrier around its rotation axis and moving the optical recording unit along a spiral track; continuously wobbling/scanning a recording spot about the spiral track; and controllably activating a light source producing said spot such that formatting marks are recorded on a plurality of adjacent tracks in the same layer in the carrier.
According to yet another aspect of the invention, there is provided a method of formatting an optical information carrier, the method comprising: providing at least one information carrier and at least one optical recording unit; rotating the carrier around its rotation axis and moving the optical recording unit along a spiral track; continuously refocusing a light beam produced by the optical recording unit in axial direction and wobbling/scanning a recording spot in lateral direction (i.e. at an angle to the track direction and the optical axis) along the track; and controllably activating a light source producing said light beam such that formatting marks are recorded on a plurality of adjacent tracks located at different layers in the carrier.
According to yet further aspect of the invention, there is provided a method of formatting a three dimensional optical information carrier, the method comprising:
The carriers may be rotated on an angle that compensates for a shift caused by a continuously changing radius of the spiral track in location of the marks recorded on the same spiral track. This rotational movement of the carrier around said common central axis may be replaced by a small linear movement of the carriers.
The multiple optical recording units may be used for recording simultaneously one formatting layer in at least one three-dimensional carrier. Alternatively or additionally, multiple optical recording units may record simultaneously a plurality of formatting layers in at least one carrier.
According to yet another aspect of the invention, there is provided a method of formatting an optical information carrier, the method comprising:
The present invention, according to its further broad aspect, provides an apparatus for formatting at least one three dimensional optical information carrier to create a plurality of formatting marks that are to be sequentially addressed when reading recording information in the carrier, the apparatus comprising: at least one optical recording unit configured for producing and focusing a light beam onto a plane inside said at least one carrier, a support unit for supporting said at least one carrier, and a control unit configured for providing a synchronized relative displacement between said at least one carrier and said at least one light beam and to timely activate the optical recording unit to produce the recoding light beam to thereby enable recording of the plurality of formatting marks within the carrier volume in an interleaved order, thereby reducing delays in recording locally adjacent formatting marks thus reducing the entire carrier formatting time.
According to yet further broad aspect of the invention, there is provided an apparatus for formatting at least one three dimensional optical information carrier, the apparatus comprising at least one optical recording unit configured for producing and focusing a light beam onto a plane inside said at least one carrier, a support unit for supporting said at least one carrier, and a control unit configured for providing a synchronized relative displacement between said at least one carrier and said at least one light beams to record a plurality of formatting marks within the carrier volume of a substantially annular cross-section, where said formatting marks are arranged about nominal positions of nodes of a grid formed by intersection between equidistantly spaced cylindrical spiral tracks, equiangular spaced radial planes and recording planes, which are substantially orthogonal to the radial planes.
According to yet another aspect of the invention, there is provided an apparatus for formatting multiple three dimensional optical information carrier, the apparatus comprising
a) a stage mounted for movement with respect to a common central axis, and carrying a plurality of spindles mounted on the stage in a circular array around said central rotation axis, with each of the spindles having its own rotation axis and carrying a respective one of the carriers;
b) a platform mounted for rotation around said central rotation axis and carrying a plurality of optical recording units arranged on the platform in a circular array around said central rotation axis, the optical recording units having parallel to each other optical axes, respectively;
c) a synchronizing mechanism for synchronizing rotations of the spindles around their rotation axes and rotation of the optical recording units around said central axis, the synchronized rotations causing a trajectory of movement of each of the optical axes to pass through the rotation axes of each of the spindles.
The information carriers are mounted on the spindles, respectively, such that the rotation axis direction of each carrier and each spindle coincide with the rotation axis direction of the optical recording units and each rotation of the optical recording unit traces at least one radial arc on each information carrier.
The synchronizing mechanism may utilize an electro-mechanical system, which operates to synchronize the rotation of spindles with optical information carriers around their rotation axes, rotation of the optical recording units and rotation of the carriers (via rotation of the stage carrying the spindles) around the central axis. Alternatively, a linear movement of stage actuators may be used (instead of rotational movement of the stage around the central axis). A suitable controller utility is provided for timely activating the optical recording units to produce recording light beams.
According to yet further aspect of the invention, there is provided an apparatus for formatting an optical information carrier, the apparatus comprising: a plurality of spindles carrying a plurality of information carriers, respectively, and mounted on a linearly moving reciprocating table, the spindles being arranged such that rotation axes of the spindles reside in one plane; a plurality of optical recording units arranged such that optical axes thereof are parallel to the rotation axes of the spindle and reside in the same plane; a mechanism configured and operable to control the rotation and reciprocating movement of the relative to the optical recording units.
The information carriers are mounted on the spindles, respectively, such that the rotation axis of the carrier and the respective spindle coincide. The synchronized reciprocating and rotational movements of the carriers and activation of the optical recording units at proper timing generates at least one optically formatted layer with formatting marks disposed on nodes of a three dimensional grid.
In order to understand the invention and to see how it may be carried out in practice, preferred embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:
The principles and execution of the method and apparatus described thereby may be understood with reference to the drawings, wherein like reference numerals denote like elements through the several views and the accompanying description of non-limiting, exemplary embodiments. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the method.
Reference is made to
The information or data is optically recorded on carrier 100 in practically any location, although it is convenient to record it on a plurality of “virtual” layers 106 as series of three dimensional regular, oblong or oblong and tilted data marks, such as ones disclosed in WO 2005/015552, assigned to the assignee of the present application. It should be noted that, although the formatting method is demonstrated on carrier 100, the method in its entirety is mutatis mutandis applicable to other types of carriers. A distance between layers 106 may be 10-15 micron. A thickness t of carrier 100 may be about 6 mm. In addition to optically recorded regular or oblong or oblong and tilted data marks representing the information, a pattern of servo or formatting marks is optically recorded on carrier 100. Formatting marks are recorded on a plurality of layers 108 that may be located at different depths of carrier 100 and the formatting marks may be similar or sometimes identical to data marks and may be of controlled size and length. The structure of layers 108 may be different from the structure of layers 106. In one embodiment, each data layer has its own formatted track, in another embodiment one formatting or servo layer may be sufficient to provide coordinate information to a number of data containing layers 106. Accordingly, each formatting or servo layer 108 is interspaced by at least one data-containing layer 106.
Formatting marks may be located on spiral tracks directed outwards or inwards, depending on the carrier rotation direction, beginning at the largest recordable dimension Dmax of an optical information carrier and ending at the smallest recordable dimension Dmin or vise versa.
In an alternative embodiment the formatting is performed in direct reference to the reference layer. This is implemented using a suitable optical system (optical recording unit) capable of tracking the reference embossed layer by standard methods, and accurately controlling the distance between the tracking focus point and the recording focus point, which distance may be changed by accurate control of the respective beams divergence. This will be described below with reference to
The formatting process may also have inherent limits such as limited working distance of a lens system, limited movement of the lens actuator at the required accuracy or limited ability to accurately couple a plurality of recording units to record accurately about the lattice nodes. Any such limit makes it advantageous to divide the formatting infrastructure of the formatted medium into a number of groups and each group is independent in terms of formatting and formatting accuracies. This results in an optical storage medium that is formatted more efficiently and has increased accuracy. The optical storage medium thus has a division into subgroups that are independent in terms of formatting and provides for tracking the formatting patterns therein.
Reference is made to
The marks are recorded on the active area of optical information carrier 100, which is bound by largest spiral track diameter Dmax on which a spiral track begins and smallest spiral track diameter Dmin on which the spiral track ends. The width L of the active area would be L=(Dmax−Dmin)/2. The number n of spiral tracks 210 that may be recorded on such a carrier would be:
n=L/T
1
wherein T1 is the average pitch of the spiral tracks.
In a practical case, where the average track diameter is 81 mm (Dmax=118 mm; Dmin=44 mm), there are about 37,000 tracks on a disc. The distance that the scanning head has to travel following the spiral track is about 9,415 meter.
If a radius 226 is traced from point 228, which is the rotation and geometric axis of carrier 100, to the largest diameter Dmax of the spiral track, it will intersect all the spiral tracks existing in carrier 100. The number of intersections of a radius with the spiral tracks is equal to the number of tracks and would be
n=L/T
1
A plurality of radii 226 exiting from point 228 may be traced and spaced such as to intersect each of formatting marks 204 residing along diameter Dmax. The angular increments ω of radii 226 may be selected such as to ensure that formatting marks 204 form a constant angular velocity servo pattern, namely formatting marks are arranged with fixed angular distances thus enabling the carrier rotation at a fixed rotation speed for all the spiral tracks, being close or far from the center of the carrier. The radii 226 contain equal number of nodes 230. The intersection points or nodes generated by the equidistantly spaced spiral tracks 210 and equiangular spaced radii 226 form a well-defined grid pattern. Accordingly, formatting marks 204 may be recorded about the nominal position (in the vicinity) of each of the nodes 230 to form a constant angular velocity servo pattern. It should be noted that a single formatting mark may be recorded in the vicinity of the respective node (in which case the number of nodes 230 is equal to the number of formatting marks present on carrier 100), or a few formatting marks may be recorded in the vicinity of the same node, e.g. being located above and/or below the node.
Thus, in some embodiments of the invention, the nodes are arranged along sections of rays (radii) along fixed angular distances were the sections of rays continue from the smallest spiral track diameter Dmin to the largest one Dmax, providing one constant angular velocity for the whole carrier. Other grid patterns, meeting the requirements of constant linear velocity or constant zonal velocity servo pattern, may be provided. Smaller subsections of radii (or rays) may be used to provide a division of the carrier into annular zones each providing for a different angular distance, different linear velocity and varying data marks density.
Formatting marks may be optically recorded on carrier 100 in any location, although it is convenient to record them on a plurality of layers 108 (
Formatting marks 204 being recorded on a plurality of virtual layers 108 in carrier 100, form a three dimensional lattice with axes being the radial mark position, angular mark position and position of the mark in the depth or what is called axial direction of carrier 100.
Generally speaking, formatting marks 204 are located in the vicinity of nodes 230 (e.g. above or below the respective node), such that the arrangement of formatting marks 204 corresponds to the arrangement of nodes 230. Each node may be associated with more than one (a few) formatting marks. The lattice structure of the grid of nodes is equivalently evident in the lattice structure of the formatting marks. The lattice structure is kept in a locality, whose size is proportional to the formatting accuracy. Radius of rotation 304 of an optical pick-up (OPU) device is selected such that its trajectory follows the locations of the intersections of spiral track 210 and radii 226 as will be described more specifically further below. Thus, carrier 100 of the present invention is formed with the formatting marks disposed in accordance with a three dimensional lattice nodes 230, which are intersections between equidistantly spaced (cylindrical) spiral tracks 210, equiangular spaced radial planes (radii) 226 and a plurality of recording planes 108 or virtual layers.
The present invention provides a novel formatted carrier and a carrier formatting method where the format is formed by grouping a certain grid of formatting marks into independent sub-volumes. Then principles of this concept are exemplified in
According to the known technique, disclosed in WO 2005/015552 to the same assignee as the present application, formatting marks are recorded by moving the recording spot formed by an OPU along track 210. According to the present invention, the formatting marks are recorded in an interleaved manner, rather than in a sequential one, thus reducing delays of the recording of formatting marks which is inherent in sequential recording.
Marks 204 are recorded in the volume of the carrier, on active area L, which for the discussed above example is about 37 mm. The number of radii traced is about 600, which means that for each layer a recording head 250 has to travel a distance of about twenty two meter only. This distance is about 430 times smaller than the distance 9,415 meter that the scanning head has to travel following the spiral track. Marks may be recorded by shorter than microsecond (100 nanoseconds) pulses. Accordingly, the carrier formatting time even at the same travel speed is much shorter. This method of formatting will be termed radial formatting.
Marks may be recorded, by activating OPU 250 at proper time, as single marks and as clusters 260 of formatting marks. For recording of clusters 260, the recording system may be equipped by an optical system that images complete clusters 260 of formatting marks 204 of appropriate configuration.
Alternatively, carrier 100 may perform both rotational (arrow 254) and reciprocating (arrow 252) movements. As shown in
For proper recording of marks 204 in accordance with the arrangement of nodes (230 in
The use of continuous movement of carrier 100 and optical recording head 250 further significantly increases the throughput of the present formatting method. This is illustrated in
A constant angular velocity servo pattern is characterized by a distance between formatting marks or symbols 204 residing on spiral tracks 210 (which are exaggerated for illustration purposes), which is gradually decreasing towards the center of the carrier along spiral track 210. To arrange the formatting marks along substantially radial lines, optical carrier 100 rotates, during each complete rotation of optical recording head 250, on an angle selected such that the rotation of the carrier compensates for a shift caused by the convexity or radial arc 284. For example, if optical information carrier 100 has 600 or 800 marks on the largest spiral track diameter and a corresponding number of radii or radial sectors, then on each complete rotation of optical recording head 250 the carrier will rotate 1/600 or 1/800 of a turn. Formatting marks 204 recording will begin with a node residing on a largest spiral track 216 and intersection of a first radius 226-a, and each next node will be located on the intersection of the next spiral track with the same radius 226-a. The recording ends with a node residing on the intersection of the same radius 226-a and a smallest diameter spiral track 218
A radius of rotation 304 of OPU 250 is selected such that its trajectory follows the locations of the intersections of spiral track 210 and radii 226. This means that all formatting or servo marks 204 (per layer) may be produced by about 600 rotations (or other number of rotations depending on the number of marks on the outer track) of the optical recording head (OPU) 250, which is at least 66 times more efficient than the 37,000 rotations required for the conventional technique of recording marks following a spiral track. Mechanical deformations, caused by the centrifugal forces and vibrational forces, limit a rotation speed of the carrier; at least 6 min may be required to format a single layer carrier by the conventional optical recording of marks at a 100 Hz rotation speed.
In addition to the discussed rotational movements of carrier 100 and OPU 250, there is a need to compensate for a continuous change in a distance between formatting marks 204 when they are recorded on the same and subsequent spiral tracks. Referring to the examples of FIGS., 2, 4, 5 and 6, the shift occurs because the diameter of spiral track 210 is continuously changing and the same number of marks 204 is recorded on each spiral track 210. For example, the recording of a mark 204-f on the largest section 216 of track 210 begins on a diameter D1, and the last mark 204-l belonging to the same track 210 is recorded on a diameter D2, which in this case is smaller than diameter D1. In order to compensate for this shift, carrier 100 may slightly move along trajectory 284. It simply rotates on a very small angle around the center 280 of rotation of OPU 250 in the course of the recording process. The rotation and geometric center 228 of carrier 100 remains, however, on trajectory 284. Another method of recording the formatting marks in spiral lattice nodes is by controlled synchronization that delays the recording performed by the OPU passage over the disk so as to have a sub-track delay. More specifically, the marks containing nodes could be considered as being produced along each radius as a set of recording times. If the recording times are the same for all the radii the natural way to connect (by a track) the recorded mark containing nodes would be circles. If the nodes of radius k are delayed relative to the nodes of ray (k−1) then the nodes will be recorded a little bit towards the center, such a sequence of nodes would form an ingoing spiral. The delay can also be achieved by synchronizing the recording OPU so that a tiny delay will be systematic.
Carrier 100 may have a plurality of formatting layers (108 in
Using synchronized rotation of optical information carrier 100 about its rotation axis 228, rotation of OPU 250 around common central axis 280 and rotation of the plurality of optical information carriers around rotational axis 280 produces a set of regular or oblong, or oblong and tilted servo symbols 204 of controlled size and shape forming a servo pattern. Marks 204 may be spatially disposed about the nominal location of nodes (230 in
Depending inter alia on the carrier structure in the embodiments of
In the conventional formatting schemes, the distance between the successive laser spots (i.e. a delay between successive recording events) while recording the formatting marks along the track is the same as that for the data reading, and is in the order of hundreds of microns, and the medium rotating speed limits the mark recording rate to hundreds of KHz. In the ‘radial’ recording scheme of the present invention (constituting an example of interleaved recording), the distance between consecutively recorded marks is in the order of one micron, enabling additional substantial increase in formatting density and throughput. Another method of substantially increasing the formatting throughput may be enabled by interleaving the recording of spiral subsets of the above-described three-dimensional lattice/grid.
Reference is made to
The refocusing of OPU 250 allows placement of a formatting mark in practically any location along an optical axed 310 of OPU 250 and at different depth in carrier 100. Hence, with the axial formatting marks formation method, the marks may be recorded at micron or sub-micron depth differences from each other and from data layers. Typically, each data layer (106 in
In a further embodiment of the invention, axial formatting is combined with the scanning spot method, and formatting marks may be recorded, for example, at three spiral radii and four depths. The marks are recorded in sequence and not concurrently, and in the interleaved order. Nevertheless, the resulting recording rate is 12 or more times higher than the rate supported by conventional methods; as a result of the interleaved order in which the marks are recorded the relative motion between the carrier and the recording unit for the recording of marks is reduced and the delay between consecutive recording events is reduced. The effective distance of motion between the recordings of marks may be tens of microns or even shorter. Axial modulation of the laser beam enables recording in a plurality of axial depths, where the method of spot scanning of the recording plane enables recording in a plurality of spiral radii. The scan is performed by moving the spot in a direction orthogonal to the OPU optical axis. The result is a 3D lattice/grid. The speed of rotation of carrier 100, scanning speed of the recording spot and OPU 250 refocusing time may be selected such that marks 204 are recorded on the nodes of a lattice equivalent to the nodes 230 of the earlier described lattices. The accuracy in which the formatting marks are recorded dictates the extent in which the lattice correlation is preserved.
Reference is now made to
A rotating platform 400 is mounted above the plane of location of information carriers 100, and is configured for carrying a plurality of optical recording systems/units (OPUs) 250 arranged in a spaced-apart relationship in a circular array. Platform 400 is associated with a driving mechanism (not shown) that drives it for rotation around its central (rotation axis) which coincides with axis 280, in a direction shown by arrow 304. The platform 400 rotation is controlled such that a trajectory (284 in
Apparatus 370 includes an electro-mechanical synchronization mechanism (not shown) configured and operable to synchronize simultaneous and continuous rotation of each of spindles 386 with the rotation of platform 400 carrying recording heads 250 such that each next rotation of optical recording head 250 traces at least one additional equidistantly angularly spaced radial arc 290 on each of the plurality of optical carriers 100. It should be noted that one OPU may format all the carriers, if the apparatus is appropriately configured and operable to enable optical and mechanical displacement between the OPU and the carriers to move the focus point accurately to every depth in the medium. The use of an arrangement of multiple OPUs (perhaps of a limited depth range) and a plurality of carriers allows for increased (factorized) formatting efficiency.
A simple relation between the rotational movement of spindles 386 and rotation of platform 400 is as follows: The rotational movements of platform 400 and spindles 386 on which information carriers 100 are mounted are synchronized such that during one complete rotation of optical recording head 250 around axis 280 (i.e. one revolution of platform 400) each spindle 386 rotates around its rotation axis 228 on an angle α determined as:
where k is the number of equiangular radial planes intersecting with the recorded layer plane, and M is the number of OPUs participating in the formatting. Other relations allow for more complex recording about the nodes of the grid, basically the requirement is that a recording OPU will be able to scan along a specific radial plane for every plane intersecting the layer plane in which the recording about the nodes is required to be performed.
Concurrently, stage 380 with the plurality of spindles 386 and carriers 100 rotates on a small angle in a direction indicated by arrow 406 around axis 280 to compensate for the shift in the position of the marks recorded on the same or the next adjacent spiral track. Continuously changing a radius of the spiral tracks causes this shift. The rotation angle required for the shift compensation is very small, since a difference between the radiuses of two adjacent marks, residing on the same spiral track, is fractions of micron. Because of this, a linear movement of stage 380 may replace the rotational movement thereof. Arrows 410 indicate the direction of such a linear movement of stage 380. A stepper motor or a piezo actuator 414 acting against a flexible resistance 418 or any other piezo actuator may provide this linear movement.
Carrier 100 may have a plurality of formatting layers with each layer being on different depth of carrier 100. The different formatting layers may be recorded by refocusing OPUs 250, or in some instances changing the distance between recording systems 250 and carriers 100. Recording spot location control system 440 is provided and configured for controlling and facilitating the focusing on a proper recording layer. Spot location control may be performed by a variety of means. In some cases, recording on a non-linear optical storage medium and particularly on a medium with two-photon absorption may require use of two lasers operating at different wavelengths shown by arrows 470 and 472. As mentioned above, apparatus 370 may support recording of clusters of marks 204, associated with one or a few nodes of the grid, e.g. by using a diffractive optical element for the beam splitting into a plurality of light components focused into separate focus spots.
Three-dimensional non-linear information carriers usually have a thickness exceeding those of conventional discs and may require refocusing in excess of the range provided by conventional OPUs. Simultaneous recording on a number of carriers 100 may require synchronized refocusing of all OPUs 250 participating in the process.
Turning back to
The second differential system consists of thread 844 made on the outer diameter of a housing 824 containing lens 818 and an inner diameter of bushing 850, and thread 852 made on the inner diameter of fixed coupler 832 and outer diameter of bushing 850. A motor 860, such as a stepper motor or a servomotor, rotates a gear 862 that engages a gear 866 made on the upper section of bushing 850. Rotation of gear 862 moves axially the lens 818 towards or from lens 816 and changes the magnification of the OPU and a focused spot location. The difference in the pitch of threads 844 and 852 determines the lens 818 movement. Pins 874 prevent rotation of lens 818. Synchronized movement of lenses 816 and 818 changes the magnification of the OPU and moves a focused spot within carrier 100 with submicron accuracy and a high speed. Arrow 880 indicates propagation direction of recording/reading laser radiation.
Reference is made to
Upon completion of the carrier optical formatting process, formatted three-dimensional optical carriers may undergo a type of quality control. The main parameters, subject to verification at the quality control process are: a) the axial distance between the formatted layers; b) parallelism of the formatted layers to each other and at least one of the surfaces of the disc; c) accumulated axial position deviation error of the layers; d) distance between formatting marks on each layer and differences, if such exist, in the distance between the marks recorded on different layers; e) distance between the first surface of the disc and first recorded layer; f) distance between the last surface of the disc and last recorded layer.
While the exemplary embodiment of the present method has been illustrated and described, it will be appreciated that various changes can be made therein without affecting the spirit and scope of the method. The scope of the method, therefore, is defined by reference to the following claims:
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IL2006/000488 | 4/20/2006 | WO | 00 | 8/4/2008 |
| Number | Date | Country | |
|---|---|---|---|
| 60672982 | Apr 2005 | US | |
| 60672982 | Apr 2005 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11290818 | Dec 2005 | US |
| Child | 11912277 | US |
