WO1996041335A2 - Systeme compact de lecture et de suivi de piste pour enregistrement optique sur bande - Google Patents

Systeme compact de lecture et de suivi de piste pour enregistrement optique sur bande Download PDF

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Publication number
WO1996041335A2
WO1996041335A2 PCT/IB1996/000718 IB9600718W WO9641335A2 WO 1996041335 A2 WO1996041335 A2 WO 1996041335A2 IB 9600718 W IB9600718 W IB 9600718W WO 9641335 A2 WO9641335 A2 WO 9641335A2
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WO
WIPO (PCT)
Prior art keywords
data
read
array
read beam
tracking
Prior art date
Application number
PCT/IB1996/000718
Other languages
English (en)
Other versions
WO1996041335A3 (fr
Inventor
Scott M. Hamilton
Billy C. Frederick
William D. Mccoy
James R. Boyd
Michael W. Montana
Original Assignee
E-Systems, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by E-Systems, Inc. filed Critical E-Systems, Inc.
Priority to AU63150/96A priority Critical patent/AU6315096A/en
Publication of WO1996041335A2 publication Critical patent/WO1996041335A2/fr
Publication of WO1996041335A3 publication Critical patent/WO1996041335A3/fr

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Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/13—Optical detectors therefor
    • G11B7/131—Arrangement of detectors in a multiple array
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/002—Recording, reproducing or erasing systems characterised by the shape or form of the carrier
    • G11B7/003—Recording, reproducing or erasing systems characterised by the shape or form of the carrier with webs, filaments or wires, e.g. belts, spooled tapes or films of quasi-infinite extent
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B7/0901—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following only
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/14—Heads, e.g. forming of the optical beam spot or modulation of the optical beam specially adapted to record on, or to reproduce from, more than one track simultaneously

Definitions

  • the present invention relates to optical tape recorders and, in particular, to a read/tracking system for retrieving data written on an optical media while automatically tracking the data recorded . on closely proximated data tracks.
  • Optical systems are now commonly used in place of magnetic systems for recording and retrieval of digitized information.
  • the data is used to digitally modulate a light beam having a predetermined intensity necessary to mark a light sensitive recording media.
  • the modulated beam is focused to a small spot and traced across the media to record the data as a fine optical pattern comprised of a number of closely spaced, microscopic dots (data marks) along a data track.
  • a data track may contain a plurality of data channels depending on the number of write beams .
  • a low intensity illumination beam is scanned along the data track and modulated by the optical pattern recorded therein.
  • the modulated beam is reflected from the media to illuminate a light detector producing an electrical signal in accordance with the beam modulation for recovery of the recorded data.
  • the system is capable of using the same objective lens for both the read function and additionally for a write function. Such a system will reduce data retrieval errors by automatically and accurately positioning the objective lens at an optimum read location
  • a read/tracking system of an optical tape recorder for optically reading a data signal on light sensitive recording media comprises a light source for emitting a read beam and optics for shaping the read beam to illuminate a plurality of recorded data channels on the recording media within a data track storing the data signal.
  • the read beam is modulated by data marks within the plurality of data channels to generate a reflected data modulated read beam.
  • the data modulated read beam is detected to recover the recorded data and generates an auto tracking control signal for automatically adjusting the positioning of an objective lens to image the illuminated pattern on a read detector and position the read beam on the recording media in response to the auto tracking control signal.
  • the read detector comprises two photosensing arrays, one for data detection and the other for tracking control.
  • FIGURE 1 illustrates an optical tape recorder system using the read/tracking system according to the present invention
  • FIGURE 2 is a schematic diagram of the read/tracking system for the optical tape recorder of FIGURE 1 showing the read/tracking subsystem and associated optics that couple a write function and an autofocus function into the optical tape recorder of FIGURE 1;
  • FIGURE 3A illustrates a partial " view of the recording media showing data tracks, data channels, data marks and the layout of the read illumination beam at the surface of the recording media;
  • FIGURE 3B illustrates one embodiment of the spacing between adjacent data channels in the data track, the spacing between adjacent data marks in a data channel and the data mark size using pulse position modulation (PPM) with the distance between adjacent data marks in each data channel being determined by the encoding scheme; likewise, for pulse width modulation (PWM) , the length of each data mark is determined by the encoding scheme;
  • FIGURE 4 is a block diagram of the read subsystem shown in FIGURE 2 illustrating the read beam source, read optics, read array and electronics module, and associated optics to retrieve data from the optical media and generate an autotracking signal;
  • FIGURE 5A illustrates the multi-beam illumination pattern as applied to the recording media
  • FIGURE 5B illustrates an alternative multi-beam illumination pattern as applied to the recording media
  • FIGURE 6 is a schematic diagram illustrating the read array and electronics module shown in FIGURE 4;
  • FIGURE 7 is a more detailed diagram of the read array shown in FIGURE 6;
  • FIGURE 8 illustrates the read after write function at the surface of the recording media
  • FIGURE 9 is a schematic diagram of the data array processing logic shown in FIGURE 7;
  • FIGURE 10 is a schematic diagram of the tracking array output logic and control shown in FIGURE 7;
  • FIGURE 11 illustrates the spatial relationship between the data image on the recording media with respect to the linear photodiode arrays of the read array.
  • FIGURE 12 is a block diagram of an alternative embodiment of the read beam source shown in FIGURE 4; and - 7-
  • FIGURE 13 illustrates an alternative embodiment for the geometry of each linear photodiode array of the read array.
  • FIGURE 1 there is shown a block diagram of a read/tracking system 102 of an optical tape recorder 100.
  • the read/tracking system 102 outputs an multi-beam illumination beam 104 and an actuator subsystem 106 for focuses and positions the multi-beam illumination beam 104 on light sensitive recording media 108.
  • the multi-beam illumination beam 104 may include either or both a write beam and a read beam.
  • the multi-beam illumination beam 104 may also include other beams, such as an autofocus beam, combined with the read and write beam as needed to perform the desired functions of an optical tape recorder.
  • the read/tracking system 102 includes light sources and optics " (see FIGURE 2) for generating and combining the included read and autofocus beams into the multi-beam illumination beam 104.
  • actuator subsystem 106 includes optics, actuator mechanisms and electronics for focusing and positioning the multi-beam illumination beam 104 onto recording media 108.
  • the present optical storage devices for which the read/tracking system 102 is designed includes multiple write beams that are focused and scanned across the recording media to record the data as a fine optical pattern, commonly referred to as a data track, comprised of multiple channels of closely spaced, microscopic dots (data marks) .
  • a data track may contain any number of data channels depending on the number of write beams.
  • the multi-beam illumination beam 104 output by the read/tracking system 102 is directed toward the actuator subsystem 106 comprised of objective lens 152, an actuator 154 and tracking-autofocus electronics 156.
  • the objective lens 152, the actuator 154 and the tracking-autofocus electronics 156 of the autofocus subsystem 106 function in combination to accurately focus and position the multi-beam illumination beam 104 on the recording media 108 to provide the reading of a multiple data channel data track.
  • the objective lens 152 is a 0.55 NA objective lens, but may have any desired value of NA to produce the desired results (i.e. resolving power) of the present invention.
  • the objective lens 152 is mounted to an actuator 154 controlled longitudinally (in response to the autofocus signal) and laterally (in response to the tracking signal) .
  • the positional movement of the objective lens to "track” the data channels (or data track) may be considered “medium” tracking of the data track.
  • the entire read head of the optical tape recorder is moved with respect to the optical media to read (or write) adjacent data tracks in serpentine fashion longitudinally along the optical media. This "coarse" tracking is usually accomplished by a stepper motor for positioning the read head.
  • the multi-beam illumination beam 104 output by the read/tracking system 102 comprises a plurality of spatially combined beams, including a collimated read beam 150 and a collimated autofocus beam 130. Additionally, a write beam or beams generated by a write subsystem (not shown) may be included in the multi-beam illumination beam 104.
  • the read beam 150 is generated by a read/tracking module 140.
  • the autofocus beam 130 is generated by an autofocus subsystem 120. Both beams, the read beam 150 and the autofocus beam 130, are combined together by combining optics 118 into the multi-beam illumination beam 104.
  • the autofocus beam 130 is optional and will be discussed later.
  • FIGURE 3A there is illustrated a piece of recording media 108 having a plurality of data tracks 250.
  • Each data track 250 is comprised of N channels of recorded data.
  • Each channel of data is recorded on the recording media 108 as a data channel 252 within the data track 250.
  • the number of data channels N depends on the number of write beams in a given optical tape recorder system.
  • FIGURE 3B there is illustrated a piece of recording media 108, specifically a portion of a data track 250 as shown in FIGURE 3A, illustrating the marking of the light sensitive media by a write system as part of an optical tape recorder. Portions of two data channels 252 within a data track 250 are shown.
  • the spacing (or channel pitch) between the centers of the adjacent data channels 252 in a data track 250 is typically about one and a half microns and may vary depending on the optics used to record the data marks on the recording media 108.
  • the spacing between the centers of the adjacent data marks 254 in the along track direction depends on the encoding scheme. Further, the length of each data mark 254 in the along track direction may vary depending on if a pulse width modulation (PWM) encoding scheme is used. Typically, for pulse position modulation (PPM) the length of a data mark is about one micron, depending on writing wavelength and NA. While the spacing between the adjacent data channels 252 and the adjacent data marks 254 set forth above is preferred, other dimensions for this spacing can be used.
  • the read/tracking module 140 includes a read beam source 146 for outputting a collimated read beam 150.
  • the read beam source 146 includes a laser diode 166 for emitting a read beam 168, a -12- lens 170 for collimating read beam 168 and a deflector/translator 174.
  • the laser diode 166 has a wavelength of 680 nm.
  • the read beam 150 is output from the read beam source 146 and is reflected through a polarization beamsplitter 148. Additionally, the read beam 150 passes through a quarter-wave plate 178 to change the polarization of the read beam 150 from linear to circular before being combined into the multi-beam illumination beam 104.
  • the read beam 176 orient and shape the read beam 168 forming a substantially rectangular illumination* field 306 or 308 (see FIGURE 3A) as focused on the media 108 to illuminate across the data track 250 having multiple data channels 252.
  • the read beam 150 as projected onto the recording media 108 is approximately 100 microns in length.
  • the deflector/translator 174 provides a mechanism 'or means to deflect the single read illumination beam 150 to either of the two read beam positions (illumination field 306 or 308 shown in FIGURE 3A) . Deflection may be accomplished by using a galvanometer. Alternatively, a translator 174 provides a means or mechanism for laterally translating the collimating lens 170.
  • the recording media 108 is shown with an illumination pattern 300 of all constituent components of the multi-beam illumination beam 104 of an optical tape recorder.
  • the illumination pattern 300 comprises a forward read beam pattern 306 combined with a write beam pattern 302 and an autofocus pattern 304.
  • the illumination pattern 300 comprises the write beam pattern 302, the autofocus pattern 304 and a reverse read beam pattern 308.
  • an alternative embodiment of the read be " am source 146 shown in FIGURE 12 utilizes a first read beam source 164 and a second read beam source 165 and requires no deflection/translation mechanisms.
  • the first read beam source 164 includes a laser diode 166a and a collimating lens 170a to produce a read beam 150a.
  • the second read beam source 165 includes a laser diode 166b and a collimating lens 170b to produce a read beam 150b.
  • the second read beam source 174 comprises the identical elements as the first read beam source 164, except that the positioning of the read beam with respect to the previously recorded data tracks is different (as discussed below) .
  • the first read beam source 164 and the second read beam source 165 provide alternating beam sources for the read beam 150, depending on the direction of movement of the recording media 108.
  • the read beam 150a and the read beam 150b are combined by a 50/50 beamsplitter 171 into the read beam 150.
  • the read beam 150 comprises the read beam 150a when the optical tape recorder 100 performs a read and/or write function when the recording media 108 is scanned in the +X direction.
  • the read beam 150 comprises the read beam 150b when the recording media is scanned in the opposite direction, that is, the -x direction.
  • the recording media 108 is shown with an illumination pattern 300 of all constituent components of the multi-beam illumination beam 104 of an optical tape recorder.
  • the illumination pattern 300 comprises a forward read beam pattern 306 combined with a write beam pattern 302 and an autofocus pattern 304.
  • the forward read beam pattern 306 corresponds to the read beam 150a generated by the first read beam source 164.
  • the second read beam source 174 is not activated when the recording media 108 is moving in the forward direction.
  • the illumination pattern 300 comprises the write beam pattern 302, the autofocus pattern 304 and a reverse read beam pattern 308.
  • the reverse read beam pattern 308 corresponds to the read beam 150b generated by the second read beam source 174.
  • the first read beam source 164 is not activated when performing a read and/or write in the reverse direction.
  • the first and second read beam sources 164, 174 alternate as the source for r;he read beam 150 depending on the direction of movement of the recording media 108 during a read and/or write cycle.
  • the optical tape recorder may position individual write beams adjacent to one another to produce a write beam pattern 310 to create the illumination pattern 300 as shown in FIGURE 5B.
  • the rectangular pattern 306, 308 of the read beam 150 is scanned along the longitudinal length of the data track 250 by movement of the recording media 108 either in the forward or reverse direction. Scanning of the read beam 150 in this manner causes the read beam 150 to be modulated by the data marks 254 of the multiple data channels 252 therein.
  • the multi ⁇ channel modulated read beam 150 is reflected by the recording media 108 back through the actuator subsystem 106 -16- to the read subsystem 140.
  • the polarization of the modulated read beam 150 is rotated from circular to a linear polarization orthogonal to the original polarization (from p- to s-polarization) by passing through the quarter- wave plate 178.
  • the modulated read beam 150 is then reflected by the polarization beamsplitter 148 and directed through read optics 144 to a two-segment mirror 184 and directed to a read array and electronics module 142.
  • the read optics 144 include a lens 180 and a lens 182 for shaping the modulated read beam 150 directed to the two- segment mirror 184.
  • the two-segment mirror 184 focuses the reflected modulated read beam 150 (one of two possible read beams) onto the read array and electronics module 142.
  • the modulated read beam 150 is imaged on a read array receiver 200, and more specifically, is imaged on a read array 206 (see FIGURE 7) that includes a data array 210 and a tracking array 208, with each array 208, 210 comprising a plurality of linear photodiodes 212.
  • the photodiodes 212 of both the tracking array 208 and the data array 210 are located on the same integrated circuit chip.
  • the distance B between the tracking array 208 and the data array 210 is generally (but not limited to) about 10 to 15 microns.
  • the read optics 144 (shown in FIGURE 4) dimensionally shape the modulated read beam 150 to illuminate both the tracking array 208 and the data array 210.
  • the combining of the tracking array 208 and the data array 210 on the same chip allows tracking information, as well as data information, to be obtained from a single image of the recording media 108. While a single chip containing both the tracking array 208 and the data array 210 is preferred, multiple chips, multiple arrays or discrete photodiodes may be used but would require additional read optics to shape and properly position the modulated read beam on the photodiodes.
  • guardband area 256 between the adjacent data tracks 250 where no data is recorded.
  • the distance between the adjacent data tracks 250 is a guardband distance 258.
  • the desired guardband distance 258 typically is about 4.5 microns (about equal to the width of 3 data channels 252) .
  • the optical tape recorder system uses the tracking function of the read/tracking system 100 of the present invention.
  • the tracking f nction provides for automatically tracking the position of data track 250 currently receiving data for recording with respect to an adjacent previously recorded data track 250a.
  • the read beam 150 scans/illuminates the data track 250 and, in addition, a portion of the adjacent data track 250a.
  • the reflected modulated read beam 150 images the spatial relationship between the data track 250 and the adjacent data track 250a.
  • the objective lens 152 (shown in FIGURE 1) of the actuator subsystem 106 is positioned to provide the desired guardband distance 258 between adjacent data tracks 250 and 250a.
  • the actuator subsystem 106 continuously positions the data track 250 at the desired guardband distance 258 from the adjacent data track 250a.
  • the read array and electronics module 142 (shown in FIGURE 6) comprises the read array receiver 200 and electronics for providing a tracking signal to the actuator subsystem 106 for positioning the objective lens 152 to position the multi-beam illumination beam 104 at the proper location on the recording media 108.
  • each data channel 252 is spatially divided so that the image of the data channel 252 covers four photodiodes 5 212.
  • the number of photo diodes K for sampling the width of the data channel 252 is defined as the amount of Kx oversampling.
  • four photodiodes are utilized resulting in 4x oversampling of each data channel 252.
  • Alternative oversampling e.g. 3x
  • 10. or greater than 4x may be used depending on the system parameters and impact on the integrity of the reconstructed data channels 252.
  • the tracking array 208 and the data array 210 each comprise one hundred twenty-
  • the tracking array 208 comprises a serial output linear photodiode array and the data array 210 comprises a parallel output linear photodiode array.
  • the number of photodiodes contained in arrays 208, 210 may be larger or smaller depending on the
  • the data array 210 retrieves the data signals recorded in the data track 250 and outputs the DATA
  • the tracking array 208 retrieves tracking information from the data signals recorded in the data tracks 250 and 250a and generates the tracking feedback signal applied to the actuator subsystem 106. This tracking information is described as the relationship between the imaged data from the recording media 108 and each photodiode in the tracking array 208.
  • the tracking array 208 integrates low energy signals over time allowing for accurate tracking information to be obtained from the edges of the read beam 150.
  • data array processing logic 214 receiving the signals generated by the photodiodes 212 of the data array 210 in response to the illumination of the photodiodes 212 by the reflected data modulated read beam 150.
  • the signal outputs from the photodiodes 212 are amplified by a bank of amplifiers 218 for further processing.
  • the amplified signals are input to a comparator register 220 for converting the amplified signals into digital signals representing the data imaged from the reflected read beam 150.
  • the read array receiver 200 converts the data from an optical image to electronic digital data.
  • the data array processing logic 214 comprises one hundred twenty-eight amplifiers and comparators, one each for each signal output by the photodiodes 212 of the data array 210.
  • the one hundred twenty-eight digital outputs from the comparator register 220 are then multiplexed by thirty-two 4 to 1 multiplexers 222.
  • the four photodiodes 212 sampling each data channel width are multiplexed to select one of the four photodiodes to represent the data signal recorded on the recording media 108 (due to the 4x oversampling of each data channel) .
  • the signal MUXSELECT determines which one of four detectors is selected for each channel.
  • thirty-two digital signals are output from the data array processing logic 214 representing the data signal recovered on the data modulated read beam 150.
  • the thirty-two digital outputs from the read array receiver 200 are input to a FPGA selector 204.
  • the FPGA selector 204 selects the appropriate sixteen digital outputs to • represent the digital signal recorded in the sixteen data channels 252 of data track 250 in response to a SELECT signal from a digital signal processor 202.
  • the digital processor 202 generates the appropriate SELECT signal from tracking information 201 received from the tracking array output logic and control module 216 of the read array receiver 200.
  • the FPGA selector 204 selects sixteen of the thirty- 5 two digital outputs to represent the data signal recorded in the sixteen data channels 252 of data track 250.
  • Control signals 203 allow for communication and control between the digital processor 202 and the read array receiver 200.
  • the read array 206 is designed for a data track comprising sixteen data channels. However, the read array 206 can be expanded or reduced to support a data track comprised of "N" data channels, with "N" being greater than or less than
  • tracking array output logic and control module 216 receiving signals generated by the photodiodes 212 of the tracking array 208 in response to the illumination of the
  • the tracking array 208 is a linear integrating photodiode array for time integrating the data image of the reflected read beam 150. This time integration provides tracking information 201 and is input to the digital signal
  • the tracking information obtained by the 4x oversampling and linear integrating photodiodes provides a method to electronically compensate for tracking offset during read and read-after- write functions.
  • Tracking information is processed by the digital signal processor 202 to generate a TRACKING signal applied to the actuator subsystem 106.
  • the actuator subsystem 106 positions the objective lens 152 transversely (see FIGURE 2) to track the data track 250 being read (either for a read or read-after- write function) .
  • the tracking array output logic and control module 216 receives signals generated by each photodiode of the tracking array 208.
  • the signals from each photodiode are amplified and accumulated by the amplifiers 224 and accumulators 226.
  • the digital signal processor 202 (shown in FIGURE 6) provides control to the accumulators 226 thus controlling the duration of the time integration of the data image of the reflected read beam.
  • the time integrated signals are then provided to the multiplexers 228.
  • the digital signal processor 202 views the time integrated signal from one or more photodiodes.
  • the digital signal processor 202 will choose to read the time integrated signals from the one hundred and twenty-eight photodiodes of the tracking array 208 in a sequential fashion. It is also possible to choose a smaller subset of the photodiodes thus increasing the frequency of obtaining the tracking information 201.
  • the output of the multiplexers 228 is analog or digital in format depending on the preference of the read/tracking system 100.
  • the tracking information obtained from read array receiver 200 enables the digital signal processor 202 to locate the guardband 256 between adjacent data track 250a and data track 250.
  • the digital signal processor 202 generates the TRACKING signal to position the actuator subsystem 106 to move slightly to maintain the guardband distance 258 at the desired guardband distance of approximately 4.5 microns.
  • the digital signal processor 202 generates the TRACKING signal to position the actuator subsystem 106 to insure the desired guardband distance between adjacent data track 250a and data track 250. Additional tracking information is then obtained from the read array receiver 200 to insure the actuator subsystem 106 is maintaining the desired guardband distance.
  • the optical tape recorder 100 of the present invention performs a read-only function on the data track 250
  • the tracking information input to the digital signal processor 202 is used to locate the guardband 256 between adjacent data track 250a and data track 250. Knowing where the guardband 256 is, the digital signal processor 202 generates the tracking information necessary to position the actuator subsystem 106 so that the data image of data track 250 is positioned in the center of the read array 206. Further, the digital signal processor 202 will generate the SELECT signal to select the appropriate digital signals (see FIGURE 7) to represent the data recorded in data track 250.
  • the geometry and magnification ⁇ " f the read beam 150 as applied to the recording media 108 provide an illumination field that is orthogonal to the data channels, as shown in FIGURES 3A, 5A and 5B. Accordingly, it is advantageous for the data recorded in the data channels to have a parallel data front. As such, this provides for a less restrictive readout design.
  • the data recorded on the recording media may be purposely "skewed" when written, as shown in FIGURE 5A.
  • This skewing may be accomplished by time-adjusting the data or by rotation of the read beams with respect to the data track length.
  • FIGURE 13 there is illustrated an alternative read beam geometry providing a read illumination field 400 as applied to the optical media.
  • the read beam is rotated at an angle with respect to the data track (or data channel) direction.
  • the entire read beam source ' is angularly rotated to produce the new read beam geometry.
  • This new geometry effectively reduces optical crosstalk at the image plane and increases the resolution. Cross-talk is minimized because the read illumination and read detectors (photodiode arrays) are, in effect, reading data at a larger data channel pitch as shown. As such, the geometry of each linear photodiode array of the read array is different .
  • the autofocus subsystem 120 includes an autofocus beam source 122 for outputting a collimated autofocus beam 13C.
  • the autofocus beam 130 is reflected through the beamsplitter 126 and is passed through a quarter-wave plate 128 to change the polarization of the autofocus beam from linear to circular.
  • the autofocus beam 130 is combined with multi-channel read beams 150 by combining optics 118 into the multi-beam illumination beam 104.
  • the autofocus beam 130 is directed by the objective lens 152 onto the recording media 108.
  • the autofocus beam 130 is reflected by the surface of the media 108 back through the objective lens 152 to the autofocus subsystem 120.
  • the polarization of the reflected autofocus beam 130 is changed by the quarter-wave plate 128 from circular to linear for a total of a ninety degree change with respect to the original linear polarization (from p- to s-polarization) .
  • the reflected autofocus beam 130 is then transmitted by the polarization beamsplitter 126 and directed to the autofocus beam receiver 124.

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Recording Or Reproduction (AREA)
  • Optical Head (AREA)

Abstract

Cette invention concerne un système de lecture et de suivi de piste d'un enregistreur optique sur bande permettant la lecture optique d'un signal de données sur un support d'enregistrement (108) photosensible pendant une fonction de lecture. Un faisceau de lecture a une forme lui permettant d'éclairer, sur le support d'enregistrement, une pluralité de canaux de données enregistrées au sein d'une piste de données contenant le signal de données. Le faisceau de lecture est modulé par des marques de données au sein de la pluralité des canaux de données de façon à produire un faisceau de lecture modulé de données réfléchies. Ce faisceau de lecture modulé de données réfléchies est détecté par le détecteur (142) afin de récupérer les données enregistrées. L'image des données dans le faisceau de lecture modulé de données réfléchies est détectée pour récupérer les données enregistrées. Ladite image des données sert aussi à produire un signal de commande de suivi de piste pour un appareil électronique (156), qui ajuste automatiquement le positionnement d'une lentille (152) pour positionner correctement le faisceau de lecture sur le support d'enregistrement. On parvient ainsi à un positionnement automatique précis sur la piste de données alors que se déroule une opération de lecture de la piste de données pendant une fonction de lecture.
PCT/IB1996/000718 1995-06-07 1996-06-06 Systeme compact de lecture et de suivi de piste pour enregistrement optique sur bande WO1996041335A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU63150/96A AU6315096A (en) 1995-06-07 1996-06-06 Compact read/tracking system for optical tape recording

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US47683995A 1995-06-07 1995-06-07
US08/476,839 1995-06-07

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WO1996041335A2 true WO1996041335A2 (fr) 1996-12-19
WO1996041335A3 WO1996041335A3 (fr) 1997-02-06

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WO (1) WO1996041335A2 (fr)
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1873762A1 (fr) * 2006-06-30 2008-01-02 Thomson Licensing S.A. Appareil et méthode pour la reproduction de données enregistreés sur un milieu d'enregistrement
EP1873761A1 (fr) * 2006-06-30 2008-01-02 Thomson Licensing, S.A. Appareil et méthode pour la reproduction de données enregistreés sur un milieu d'enregistrement

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US5081617A (en) * 1990-09-24 1992-01-14 Creo Products Inc. Optical system for simultaneous reading of multiple data tracks
US5400308A (en) * 1992-08-19 1995-03-21 Olympus Optical Co., Ltd. Optical information recording/reproducing device capable of recording information on a moving medium and reproducing information by using reproducing light beams

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US4815067A (en) * 1986-10-06 1989-03-21 Thorn Emi Plc. Optical rotary headwheel tape recording system
US5081617A (en) * 1990-09-24 1992-01-14 Creo Products Inc. Optical system for simultaneous reading of multiple data tracks
US5400308A (en) * 1992-08-19 1995-03-21 Olympus Optical Co., Ltd. Optical information recording/reproducing device capable of recording information on a moving medium and reproducing information by using reproducing light beams

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1873762A1 (fr) * 2006-06-30 2008-01-02 Thomson Licensing S.A. Appareil et méthode pour la reproduction de données enregistreés sur un milieu d'enregistrement
EP1873761A1 (fr) * 2006-06-30 2008-01-02 Thomson Licensing, S.A. Appareil et méthode pour la reproduction de données enregistreés sur un milieu d'enregistrement
US7852586B2 (en) 2006-06-30 2010-12-14 Thomson Licensing Device and method for scanning data stored on a recording medium

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WO1996041335A3 (fr) 1997-02-06
ZA964613B (en) 1996-12-12
AU6315096A (en) 1996-12-30

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