Patent Application
20080062244
is a systematic illustration of one example of a laser writing system writing upon optical media according to an example embodiment.
Optics 46 are associated with each of lasers 44 and direct coherent light generated by lasers 44 towards alignment optics 48 and 50. In the example illustrated, optics 46a and 46b direct laser light from lasers 44a and 44b, respectively, towards alignment optics 48. Optics 46c directs laser light from laser 44c towards alignment optics 50. In one embodiment, optics 46 each comprise one or more lenses or mirrors.
Alignment optics 48, 50 each comprise one or more optical components configured to redirect laser light from lasers 44 towards objective lens 52. In the example illustrated, optics 48, 50 align laser light received from lasers 44 such that the laser beams are directed towards objective lens 52 along a substantially coextensive or aligned optical path. In the particular example illustrated, optics 48 aligns laser light from lasers 44a and 44b. Optics 50 further directs and aligns laser light from laser 44c with the already aligned laser light from lasers 44a and 44b. In the particular example illustrated, optics 48 and optics 50 comprise a single optical element, a dichroic mirror. In other embodiments, one or both of optics 48 and 50 may comprise other optical arrangements or components configured to align laser light or laser beams from multiple lasers.
Objective lens 52 comprises a lens configured to receive the aligned laser light from lasers 44 and to direct and focus the aligned laser light on to multiple layers of optical media 42. In particular embodiments, objective lens 52 may be movable along an axis substantially perpendicular to the layers of optical media 42 to adjust focus or the focal point of the lasers. In particular embodiments, objective lens 52 may additionally or alternatively be movable in a direction substantially parallel to the layers of optical media 42 to facilitate finite position adjustments, such as tracking, of the laser beams with respect to optical media 42.
Optical media 42 comprises a structure including multiple layers configured to be concurrently written upon by writing system 20. Optical media 42 includes writable layers 70a, 70b and 70c (collectively referred to as writable layers 70) and spacer layers 72 and 74. Writable layers 70 each comprise one or more layers of one or more materials or elements configured to change one or more optical properties in response to being irradiated with laser light. Such light may be in the visible, infrared or ultraviolet light spectrums. According to one embodiment, each of layers 70 comprises one or more thermochromic materials configure change optical properties (such as optical density) when subjected to energy such as infrared radiation, ultraviolet radiation or visible light.
For example, in one embodiment, such thermochromic materials may include a leuco dye which may change color with the application of heat or in the presence of an activator (developer). In one embodiment, the dye may include fluoran-based compounds. In some embodiments, layers 70 may additionally include a radiation-absorbing material to facilitate absorption of one or more wavelengths of marking radiation. Examples of such a radiation-absorbing material include an infrared dye. In one embodiment, each of layers 70 may be configured to change between a light translucent state and a darkened light-absorbing or light-attenuating state in response to being irradiated by energy such as from a laser. One example of such a material includes BK-400 or Black 400 commercially available from Nagase America Corporation, New York, N.Y. In other embodiments, each of layers 70 may alternatively include other materials.
According to one embodiment, each of layers 70 may have a different composition such that each of layers 70 reflect or absorb light differently upon being irradiated with substantially similar amounts of energy. For example, in one embodiment, one or more of layers 70 may be configured to reflect (or absorb) a different color of light upon being irradiated. In particular embodiments, layers 70 may be configured to reflect different shades of a particular color of visible light upon being irradiated. In some of embodiments, layers 70 may each be configured to reflect a different color of light, wherein the particular shade of light reflected by layer depends upon the extent to which it is irradiated. In some embodiments, layers 70 may be configured to reflect different monochromatic or grayscale shades of visible light.
According to one embodiment, layers 70 may be configured to absorb colors of light that when selectively combined with one another reflect a range of multiple colors. For example, in one embodiment, layers 70 may be configured to absorb distinct wavelengths of light so to provide cyan, magenta and yellow visible light upon being irradiated, facilitating half-toning or other techniques to provide a large number of colors for optical media 42.
In such embodiments where layers 70 reflect different colors, shades of colors or shades of monochromatic light, the reflection of light by layers 70 may be used to enhance labeling of optical media 42. For purposes of this disclosure, the term “label” shall mean any image, graphic, photo, drawing, picture, alphanumeric symbols, design and the like that are visible to a human eye. Such labeling may directly communicate information regarding the content or characteristic of the data on disc 20 to a person. Such labeling may also alternatively visually communicate other un-encoded information to a person.
In lieu of being written upon with labeling, layers 70 may alternatively be written upon with data. For purposes of this disclosure, the term “data” shall mean information that is encoded so as to be machine or computer-readable. For example, information may be digitally encoded with binary bits or values. Such data may have different formats such as various presently or future created music, photo and document formats. Although the existence of the data on the disc may, in some embodiments, be visually seen by the human eye as darker or lighter rings on the disc, the content or information encoded by the data is generally not readable by a human eye. In other words, the darker or lighter rings that may be viewed on the disc do not communicate information to a person viewing the rings and do not identify or label characteristics of the data.
Spacer layers 72 and 74 each comprise one or more layers of one or more transparent materials extending between layers 70. Layers 72 and 74 space apart layers 70 by distances substantially equal to the working distance differences between the different wavelengths of laser light used by writing system 20. For purposes of this application, the term “working distance” shall mean the distance from the final objective lens focusing the laser beams and the focal point of such laser beams. Laser beams of different wavelengths have different focal points when focused by the same lens. The “working distance difference” of two laser beams is the difference between their respective focal points when transmitted through the same optical system. As a result of the different working distance difference, laser light from each of lasers 44 and directed to optical media 42 by objective lens 52 concurrently irradiates the different layers 70 of optical media 42. According to one embodiment, spacer layers 72, 74 comprise polycarbonate. In other embodiments, spacer layers 72, 74 may be formed from other materials. In the example illustrated, layer 72 extends between layers 70a and 70b. Layer 74 extends between layers 70b and 70c.
According to one embodiment, laser 44a emits laser light 80a having a wavelength of approximately 405 nm (CD writing construction), laser 44b emits laser light 80b having a wavelength of approximately 650 nm (DVD writing construction) and laser 44c emits laser light 80c having a wavelength of approximately 780 nanometers (Blu-ray writing construction). In such an embodiment, spacer layer 72 has a thickness of at least about 195 μm, less than or equal to about 405 μm and nominally about 300 μm, the working distance difference between laser light 80a and 80b. Spacer layer 74 has a thickness of at least about 225 μm, less than or equal to about 475 micro letters and nominally about 350 μm, the working distance difference between laser light 80b and 80c. In other embodiments, these thicknesses may vary depending upon a dispersion of the objective lens or a material index of the objective lens 52 of the particular system 20. As a result, laser beams 80a, 80b and 80c (collectively referred to as laser beams or laser lights 80) concurrently irradiate layers 70a, 70b and 70c, respectively, to independently write labels or data upon such layers 70.
Although media 42 is illustrated as including three writable layers 70 spaced part by two intermediate spacer layers 72, 74, in other embodiments media 42 may alternatively include two writable layers separated by a single spacer layer or may include greater than three spaced apart writable layers. Optical media 42 may include additional layers as well. For example, optical media 42 may additionally include one or more reflective layers, one or more protective coatings or layers, and one or more label or data layers configured to be optically read by a laser and sensing device, configured to be visibly seen by an observer or configured to be optically written upon by a laser from an opposite side of media 42. In one embodiment, optical media 42 may comprise an annular disc. In other embodiments, media 42 may have other configurations.
Drivers 24 comprise integrated circuits configured to provide their respective lasers 44 with modulated electrical current which drives the lasers 44. Although drivers 24 are illustrated as separate elements, in some embodiments, drivers 24 may be provided by a single integrated circuit or other electronic device.
Controller 40 comprises one or more processing units configure to generate control signals for directing drivers 24 to appropriately or selectively modulate and control the laser light being emitted by lasers 44 to selectively write upon one or more of layers 70 of optical media 42. For purposes of this application, the term “processing unit” shall mean a presently developed or future developed processing unit that executes sequences of instructions contained in a memory. Execution of the sequences of instructions causes the processing unit to perform steps such as generating control signals. The instructions may be loaded in a random access memory (RAM) for execution by the processing unit from a read only memory (ROM), a mass storage device, or some other persistent storage. In other embodiments, hard wired circuitry may be used in place of or in combination with software instructions to implement the functions described. Controller 40 is not limited to any specific combination of hardware circuitry and software, nor to any particular source for the instructions executed by the processing unit.
In operation, controller 40 generates control signals based upon either data information to be written to one or more of layers 70 or based upon label information (for example bitmap information) to be written on one or more of layers 70 of optical media 42. In response to receiving such control signals, drivers 24 supply modulated electrical current to their associated lasers 44 to modulate laser beams 80. As a result, different portions of each of layers 70 are differently and concurrently irradiated by laser beams 80. Because multiple layers 70 are concurrently written upon, the writing of label or data information to optical media 42 may be less time-consuming. In those embodiments in which optical pickup unit 22 utilizes lasers 44 configured to write upon existing optical media constructions (CD, DVD, Blu-ray and others), optical pick up unit 22 may comprise an existing superdrive optical pick up unit (i.e., an optical drive configured to write or read or multiple optical media constructions at different times) which has been modified to include alignment optics, reducing cost.
Substrate layer 152 comprises a layer of transparent material configured to permit the transmission of coherent light therethrough to layers 154 and 158 and the reflection of light from layer 158 back through layer 152 for being read by a sensing device facing data side 159 of media 142. According to one embodiment, layer 152 additionally serves as a base or supporting layer for layer 154 during fabrication of media 142. According to one embodiment, layer 152 comprises polycarbonate. In other embodiments, layer 152 may be formed from other transparent materials.
Layer 154 comprises one or more layers of one or more materials configured to store data. In one embodiment, layer 154 is configured to be written upon by electromagnetic energy, such as a laser. In particular, layer 154 is configured to be written upon with a laser so as to encode binary or other machine-readable data in layer 154. In one embodiment, such data is written in layer 154 along spiral grooves extending about a rotational axis of media 142. In one embodiment, layer 154 comprises a layer or film of material which changes in optical characteristic upon being irradiated with a laser. Examples of such a material include a thermochromic material or phase-change material other material configured to change between a light translucent state and a darkened light-absorbing or light-attenuating state in response to being irradiated by energy such as from a laser. One example of such a material includes BK-400 or Black 400 commercially available from Nagase America Corporation, New York, N.Y. In other embodiments, writable layer 154 may alternatively include other materials. In other embodiments, other materials that change between different optical states upon being irradiated with a laser may be employed.
In other embodiments, layer 154 may be preconfigured or fabricated with grooves or pits representing a fixed set of data. Examples of data portion 145 which is preconfigured include, but are not limited to, discs that are stamped or other wise formed from masters. Such preconfigured data portions 145 include preconfigured CDs, DVDs, Blu-ray discs and the like.
Substrate layer 156 comprises one or more layers of one or more materials spacing data layer 154 from label portion 147. In one embodiment, layer 156 further serves as a base or foundation layer upon which reflective layer 158 is formed during fabrication of media 142. In one embodiment in which data portion 145 comprises a DVD, layer 156 has a thickness of about 600 μm. In another embodiment in which data portion 145 comprises a Blu-ray disc, layer 156 has a thickness of about 1100 μm. In one embodiment in which data portion 145 is configured to permit light to be reflected off reflective layer 158 from label side 160 in reviewing label portion 147, layer 156 is formed from a transparent material. According to one embodiment, layer 156 is formed from polycarbonate. In other embodiments, layer 156 may be formed from other transparent, translucent or opaque materials.
Reflective layer 158 comprises one or more layers of one or more reflective materials having sufficient reflectivities so as to reflect light that has passed through data layer 154 back towards an optical sensing device located opposite side 159 of media 142. In one embodiment, layer 158 comprises a layer of one of more metals which are highly reflective such as silver or aluminum. In other embodiments, other reflective metals or nonmetals may be used.
According to one method of fabrication, layer 158 comprises a single film deposited upon substrate layer 156. Layer 154 comprises single layer of writeable material deposited upon substrate layer 152. Layers 156 and 158 and layers 152 and 154 are then stacked and joined to one another with layers 154 and 158 sandwiched between layers 152 in 156. In other embodiments, data portion 145 may be formed in other ways.
Label portion 147 comprises a multilayer arrangement configured such that multiple layers may be concurrently written upon by writing system 20 (shown in FIG. 1). Label portion 147 is coupled to data portion 145 and includes reflective layer 162, writable layers 170a, 170b and 170c (collectively referred to as writable layers 170) and spacer layers 172, 174. Reflective layer 162 comprises one or more layers of one or more materials having sufficient reflectivities so as to reflect visible light that has passed through writable layers 170 back towards a person viewing label side 160 of media 142. In one embodiment, layer 162 comprises a layer of one of more metals which are highly reflective such as silver or aluminum. In other embodiments, other reflective metals or nonmetals may be used. In particular embodiments, reflective layer 162 may be omitted, wherein layer 156 is transparent, permitting light from side 160 to be reflected by layer 158 or wherein light emanating from side 160 is reflected by layers 170.
Layers 170 and spacer layers 172, 174 are substantially similar to layers 70 and spacer layers 72, 74, respectively, described with respect to
Layer 271 is similar to layers 270 in that layer 271 is configured to be written upon by a laser beam 80 from writing system 20. Layer 271 is not spaced from layer 270a by a working distance difference between two of laser beams 80. In the particular example illustrated, layer 271 is directly adjacent to layer 270a. In other embodiments, layer 271 may be spaced from layer 270a by intermediate transparent layers having a thickness less than the working distance difference.
To write upon layer 271, the focus of the laser beam 80 used to write upon layer 270a is adjusted to alternatively write upon layer 271. In one embodiment, such adjustment may be achieved with a focus servo coupled to objective lens 52 of optical pickup unit 22 (shown in
Reflective layer 358 comprises one or more layers of one or more reflective materials having sufficient reflectivities so as to reflect light that has passed through layers 370 and 372 back towards an optical sensing device located opposite side 359 of media 142. In one embodiment, layer 358 comprises a layer of one of more metals which are highly reflective such as silver or aluminum. In other embodiments, other reflective metals or nonmetals may be used.
Layers 370 each comprise one or more layers of one or more materials or elements configured to change one or more optical properties in response to being irradiated with laser light. Such light may be in the visible, infrared or ultraviolet light spectrums. Layers 370 are similar to layers 70 (shown described with effective
Spacer layer 372 comprises one or more layers of one or more transparent materials between layers 370. In one embodiment, spacer layer 372 comprises polycarbonate. In other embodiments, spacer layer 372 may have other configurations. Spacer layer 372 spaces layer 370a from layer 370b by a distant substantially equal to a working distance difference between two of laser beams 80. For example, in one embodiment, spacer layer 372 may have a thickness of 300 μm, a working distance difference between laser beam 80a from laser 44a end of laser beam 80b from laser 44b, permitting lasers 44a and 44b to concurrently write data to layers 370. Such data may be read from layers 370 by selectively focusing a laser onto one of layers 370 and sensing light that is passed through the layer 370 and that has been reflected by layer 358. During such reading, signals resulting from the layer 370 not being read may be filtered out.
Sled 484 comprises a mechanism configured to move optical pickup unit 22 radially with respect to media 42. Sled 484 includes a guide and an actuator (not shown). The guide comprises a structure configured to physically support optical pickup unit 22 as optical pickup unit 22 is moved relative to media 42. The actuator moves optical pickup unit 22 along the guide relative to media 42. In one embodiment, the actuator may comprise a DC or stepper motor. In other embodiments, other motors or actuators may be employed.
Servo 486 comprises a mechanism configured to move and adjust positioning of the objective lens 52 or other optics of optical pickup unit 22. Servo 486 includes a first actuator configured to move the objective lens in a direction generally perpendicular to a face of media 42 to adjust a focus of the laser generated by optical pickup unit 22. Servo 486 further includes a second actuator configured to move the objective lens 52 in a direction radial with respect to the face of media 42 to adjust tracking of the lasers generated by optical pickup unit 22. In one embodiment, the first and second actuators comprise motors. In particular embodiments, the first and second actuators may comprise voice coils. In other embodiments, other actuators may be used.
In operation, controller 40 generates control signals directing laser drivers 24 provide appropriately modulated electrical currents to the lasers 44 (shown in
Although the present disclosure has been described with reference to example embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the claimed subject matter. For example, although different example embodiments may have been described as including one or more features providing one or more benefits, it is contemplated that the described features may be interchanged with one another or alternatively be combined with one another in the described example embodiments or in other alternative embodiments. Because the technology of the present disclosure is relatively complex, not all changes in the technology are foreseeable. The present disclosure described with reference to the example embodiments and set forth in the following claims is manifestly intended to be as broad as possible. For example, unless specifically otherwise noted, the claims reciting a single particular element also encompass a plurality of such particular elements.
