Patent Application
20120057443
The present invention relates to techniques for forming visible characters and/or figures on an information recording surface of an information recording medium, and recording information on the information recording surface.
There is a conventional technique to irradiate laser beams onto a data recording surface of a recordable optical disc to form visible characters and/or images (for example, see Patent Documents 1, 2, and 3). This technique forms, on the data recording surface, areas respectively with different laser-beam reflectivities, which allows predetermined characters and/or images to be visible. For example, displaying information, such as a title, associated with recorded data as a visible image eliminates the need to write the information associated with the recorded data by hand, or to print the information, thus facilitating determination of optical discs.
A method of forming visible images set forth above will be described with reference to
Overwriting data to be recorded, referred to as “record data”, into an area, referred to as a “visible-image area”, on which a visible image has been formed may reduce recording characteristics. For this reason, a visible-image area is normally formed on a part of a data recording surface, and record data is written into a unrecorded area on which no visible-image areas have been formed.
As described above, in the art, because no record data is recorded on visible-image areas, an optical disc in which a visible-image area has been formed may have a storage capacity for record data lower than a storage capacity for record data of another optical disc in which no visible-image areas have been formed. It is desirable therefore to provide a technology that enables overwriting record data on a visible-image area without reducing recording characteristics.
In addition, for recording record data an area other than visible-image areas, it is necessary to identify boundaries between visible-image areas and unrecorded areas. For this reason, it is also desirable to provide a technology that enables record data to be recorded without regard to the boundaries between visible-image areas and unrecorded areas.
The present invention has been made in view of the aforementioned circumstances, and has an example of a purpose of providing information recording apparatuses, information recording methods, and computer programs, which are capable of recording record data over a recording surface including a visible-image area under a same condition, and improving recording characteristics of an area on which the record data has been recorded.
In order to achieve such a purpose provided above, a first aspect of the present invention is an information recording apparatus for irradiating a laser beam on an information recording surface of an information storage medium to record information, the information recording apparatus. The information recording apparatus includes a visible-image forming means that irradiates a laser beam on the information recording surface under a first recording condition to form a visible character or a visible image on the information recording surface, and a record-data recording means that irradiates a laser beam on the information recording surface under a second recording condition to write record data on the information recording surface. A first area on which the laser beam is irradiated by the visible-image forming means under the first recording condition and a second area on which the laser beam is irradiated by the record-data recording means under the second recording condition are at least partly overlapped with each other.
A second aspect of the present invention is an information recording method of irradiating a laser beam on an information recording surface of an information storage medium to record information. The information recording method includes a visible-image forming step that irradiates a laser beam on a first area of the information recording surface under a first recording condition to form a visible character or a visible image on the first area, and a record-data recording step that irradiates, after execution of the visible-image forming step, a laser beam on a second area of the information recording surface under a second recording condition to write record data on the second area, the second area including the first area. The second recording condition is to set a pulse width of a write signal for writing a predetermined mark to be recorded to be shorter than an optimum pulse width of the write signal for writing the predetermined mark.
A third aspect of the present invention is an information recording method of irradiating a laser beam on an information recording surface of an information storage medium to record information. The information recording method includes a record-data recording step that irradiates a laser beam on a third area of the information recording surface under a third recording condition to write record data on the third area, and a visible-image forming step that irradiates, after execution of the record-data recording step, a laser beam on at least part of the third area under a fourth recording condition to change a reflectivity from the information recording surface, thus forming a visible character or a visible picture on the at least part of the third area. The third recording condition is to set a pulse width of a write signal for writing a predetermined mark to be recorded to be longer than an optimum pulse width of the write signal for writing the predetermined mark.
A fourth aspect of the present invention is a computer program that functions a computer as each means of the information recording apparatus according to the first aspect of the present invention.
(a) of
(a) of
(a) of
(a) of
(a) of
(b) of
An embodiment of the present invention will be described hereinafter with reference to the drawings.
<Data Recording Method>
A data recording method according to this embodiment of the present invention will be outlined. The data recording method according to this embodiment is a method of, after the form of a visible image on a data recording surface of an optical disc as an information recording medium using the DC writing, recording record data on a given area including a visible-image area in the data recording surface under the same recording condition; the same recording condition will be referred to as a “special recording condition”. Note that “record data” according to this embodiment means data without including data, such as display data, for forming visible images.
This will be specifically described with reference to
The data recording method according to this embodiment permits overwriting of record data in a visible-image area, thus preventing the reduction of the storage capacity of an optical disc even if a visible image has been formed in a data recording surface of the optical disc. The data recording method according to this embodiment also can write record data over a data recording surface under the same recording condition (the special recording condition) without regard to visible-image areas. This can eliminate the need of special control around each of the boundaries.
Note that recordable optical discs to be used in this embodiment are normal discs including available recordable optical discs, such as CD-R/RW, DVD±R/RW, and BD-R/RE.
<Experiment Data>
Next, the data recording method according to this embodiment will be described using specific experiment data. Note that this experiment was carried out by: forming a visible-image area in an available DVD-R using the DC writing, overwriting record data on the formed visible-image area, and measuring the recording characteristics of the visible-image area on which the record data has been recorded. Note that the DC writing was carried out at 1× write speed, and the writing of the record data was carried out at 2× write speed.
In the write of record data, two recording conditions were used, one of which is a normal recording condition using a normal strategy, the other of which is a special recording condition using a special strategy.
The normal strategy is a write strategy that adjusts, relative to an optimum pulse width, specifically, 2.20 T, of a write signal for writing a shortest mark to be recorded, pulse widths of write signals for writing other marks (4 T to 14 T) to be recorded in order to make better recording characteristics. Hereinafter, write power in the normal recording condition will be referred to as “normal power”, and the write strategy in the normal recording condition will be referred to as a “normal strategy”. (a) of
Note that the optimum pulse width means a pulse width that allows recording characteristics, which are obtained by writing record data on an unrecorded area using the pulse width, to be optimized; the unrecorded area is an area of a data recording surface on which no visible images are formed and no record data are recorded. In this embodiment, the write strategy means the pulse width of a write signal, and control of the write strategy means adjustment of the pulse width of a write signal.
The special strategy is a write strategy that adjusts, relative to a pulse width (specifically, 1.45 T), pulse widths of write signals for writing other marks (4 T to 14 T) in order to make better recording characteristics; the pulse width is lower than the optimum pulse width (specifically, 2.20 T) of a write signal for writing the shortest mark. Hereinafter, write power in the special recording condition will be referred to as “special power”, and the write strategy in the special recording condition will be referred to as a “special strategy”. (b) of
Note that jitter represents the quality of recording characteristics, and therefore, the lower a jitter value is, the higher the quality of recording characteristics is. Specifically, the recording characteristics are good as long as a jitter value is equal to or lower than 8 percent. If a jitter value is equal to or higher than 10 percent, the recording characteristics deteriorate so that regeneration of corresponding record data may be disabled.
Let us consider the results of the experiments when record data is recorded when no DC writing is carried out with reference to
In the normal recording condition, the jitter value in an area on which record data has been recorded when no DC writing is carried out is 6.0 percent, which shows that the recording characteristics are excellent. In the special recording condition, the jitter value in an area on which record data has been recorded when no DC writing is carried out is 6.6 percent, which shows that the recording characteristics are excellent. Specifically, each of the normal recording condition and the special recording condition allow the recording characteristics of a corresponding area on which record data has been recorded to be excellent. Note that, in the normal recording condition, the reflectivity of an area on which record data has been recorded when no DC writing is carried out is 54.9 percent, and, in the special recording condition, the reflectivity of an area on which record data has been recorded when no DC writing is carried out is 55.1 percent.
Next, let us consider the results of the experiments when record data is recorded after DC writing has been carried out with reference to
In the normal recording condition, as illustrated in (a) of
For example, if record data is recorded in the normal recording condition, as illustrated in (a) of
If the jitter is allowed to vary up to 10 percent to thereby preferentially maintain the variation in the reflectivity, the DC write power must be equal to or lower than 4.7 mW. If the DC write power is equal to or lower than 4.7 mW, the reflectivity of the visible-image area is lied within the range from 50.5 percent to 54.9 percent. Thus, the rate of variation of the reflectivity relative to the reflectivity of another area on which no DC writing is carried out is set to be substantially 8 percent, which is equal to: (54.9−50.5)/54.9.
The variation range of the reflectivity is allowed to have no more than the order of 8 percent for recording record data in the normal recording condition. This is because, if the variation range of the reflectivity were set to be higher than the order of 8 percent, the jitter would more deteriorate to cause a risk of record data being non-regenerated.
Thermal interference between recorded marks may cause the recording characteristics to deteriorate. For example, in order to write record data into a DVD-R, irradiating a laser beam onto a dye-based recording layer causes a dye to be thermally decomposed so that recorded marks are formed. However, laser-beam irradiation for forming a recorded mark may affect on adjacent recorded marks, resulting in deterioration of the recording characteristics. The DC writing carried out according to this embodiment may increase the affect. The higher the DC write power is, the more increased the affect is. This may increase deterioration of the recording characteristics due to thermal interference.
Thus, in order to prevent deterioration of the recording characteristics due to thermal interference, the special strategy in the special recording condition sets laser-beam irradiation time for forming a mark to be shorter than laser-beam irradiation time of the normal strategy for forming a mark.
Specifically, as illustrated in (b) of
In the special recording condition, as illustrated in (a) of
For example, if record data is recorded in the special recording condition, as illustrated in (a) of
If the jitter is allowed to vary up to 10 percent to thereby preferentially maintain the variation in the reflectivity, the DC write power must be equal to or lower than 5.8 mW. If the DC write power is equal to or lower than 5.8 mW, the reflectivity of the visible-image area is lied within the range from 36.2 percent to 55.1 percent. Thus, the rate of variation of the reflectivity relative to the reflectivity of another area on which no DC writing is carried out is set to be substantially 34 percent, which is equal to: (55.1−36.2)/55.1.
The variation range of the reflectivity is allowed to have no more than the order of 34 percent for recording record data in the special recording condition. This prevents deterioration of the jitter while maintaining wide the variation range of the reflectivity. As described above, even if a visible image is formed on a data recording surface of an optical disc, the special recording condition provides good recording characteristics of a visible-image area on which record data has been recorded.
Note that, if record data is recorded in the special recording condition, the jitter corresponding to a value of the DC write power at which the variation of the reflectivity starts, that is, 4.5 mW or thereabout takes 6.3 percent. This value 6.3 percent of the jitter is lower than a corresponding value of the jitter, such as 6.6 percent if no DC writing is carried out. Specifically, if record data is recorded in the special recording condition, performing DC writing with the value of the DC write power at which the variation of the reflectivity starts allows recording characteristics to get better in comparison to recording characteristics with no DC writing.
Note that the experiments set forth above measured the jitter as a value indicative of the quality of recording characteristics, but can measure PI error as a value indicative of the quality of recording characteristics.
(a) of
Note that the DC writing was carried out at 1× write speed, and the writing of the record data was carried out at 2× write speed. The DC write power was 5.7 mW, the special power in the special condition was 16.8 mW, the special strategy in the special condition was 1.45 T, which is a pulse width of a write signal for writing the shortest mark.
Normally, if a value of the PI error were equal to or greater than 280, the corresponding recording characteristics would deteriorate so that the record data would not be regenerated. However, the result of the experiment set forth above demonstrates that value of the PI error are limited to be equal to or lower than substantially 50, which shows that the visible-image area has good recoding characteristics.
<Structure of Information Recording Apparatus>
The structure of an information recording apparatus 100 that forms invisible images using the data recording method set forth above, and records record data will be described hereinafter.
The information recording apparatus 100 can be designed as a computer equipped with a DVD (Digital Versatile Disk) recorder or a DVD drive. The information recording apparatus 100 records information on an optical disc 1. Each component described hereinafter can be controlled by a system controller (not shown).
A driver 2 is operative to control the rotation of the optical disc 1, and send, to a control-signal generator 13, reference-angle information.
An irradiating unit 3 consists mainly of an LD (Laser Diode; semiconductor laser), and is adapted to irradiate a laser beam to the optical disc 1 to thereby carry out recording and playback of information on the optical disc 1.
A receiving unit 4 consists mainly of a photo diode (PD), and is configured to receive light reflected from the optical disc 1 based on the irradiated laser beam.
A slider 5 is adapted to move, in a radial direction of the optical disc 1, a pickup head unit (PUH) consisting mainly of the irradiating unit 3 and the receiving unit 4.
A radial position detector 6 is adapted to detect a radial position of the PUH, and to send, to the control-signal generator 13, information indicative of the radial position of the PUH.
A reproducing characteristic measuring unit 7 is adapted to measure reproducing characteristics (recording characteristics) of a portion recorded at OPC (Optimum Power Control), and send, to a write-power searching unit 9, a result of the measurement.
A disc information obtaining unit 8 is adapted to obtain disc information previously stored in the optical disc 1; this disc information of the optical disc 1 includes its manufacture, its model number, its write strategy, and the like. The disc information obtaining unit 8 is also adapted to send, to a memory 10, the obtained information, and adapted to send, to a display position calculator 12, recording start position of record data.
The write power searching unit 9 is configured to select a write power level based on a variation of a write power level for the OPC and the reproducing characteristics sent from the reproducing characteristic measuring unit 7; the write power level for the OPC stepwisely varies for determining an optimum write power level. The selected write power level allows the reproducing characteristics to be most improved.
The write power searching unit 9 is also configured to send, to a recording condition controller 14, information associated with the optimum write power level.
The memory 10 stores therein information (DC write-power information) d10 associated with DC write power for forming visible images, and information (special strategy information) d20 for writing record data. The memory 10 is operative to determine, based on the disc information sent from the disc information obtaining unit 8, an optimum item of the DC write-power information d10 and an optimum item of the special strategy information d20, and send, to the recording condition controller 14, the determined optimum item of the DC write-power information d10 and the determined optimum item of the special strategy information d20.
Note that the structure of the DC write-power information d10 is not limited to the data structure illustrated in
Note that the structure of the special strategy information d20 is not limited to the data structure illustrated in
Note that the DC write-power information d10 illustrated in each of
A record-data capacitance checker 11 is adapted to check the capacity of the record data, and send, to the display position calculator 12, the checked capacity of the record data.
The display position calculator 12 is adapted to calculate, based on the recording start position of the record data sent from the disc information obtaining unit 8 and the capacity of the record data sent from the record-data capacity checker 11, a data recording area required to record the record data. The display position calculator 12 is also adapted to generate, based on display data for forming a visible image and the calculated data recording area, information of a display area on which DC writing is to be carried out, and send, to the control signal generator 13, the generated display-area information; the display-area information specifically includes a radial position and an angle.
The control signal generator 13 is operative to continuously grasp, based on the reference angle information sent from the driver 2 and the radial position information sent from the radial position detector 6, the location of the PUH. The control signal generator 13 is also operative to generate, based on the display-area information sent from the display position calculator 12 and the continuously grasped location of the PUH, DC recording control signals, and send, to the recording condition controller 14, the generated DC recording control signals.
The recording condition controller 14 is adapted to generate write signals (write pulses) according to each of the modes of: execution of the OPC, forming of a visible image (execution of the DC writing), and writing of record data. The recording condition controller 14 is also adapted to send, to the irradiating unit 3, the generated write pulses. Specifically, the recording condition controller 14 is adapted to send, in the mode of execution of the OPC, OPC irradiating signals generated based on OPC write power and the corresponding special strategy to the irradiating unit 3 in order to search for optimum write power. The recording condition controller 14 is also adapted to send, in the mode of forming of a visible image, DC write signals based on the DC recording control signals and DC write power information to the irradiating unit 3. The recording condition controller 14 is further adapted to send, in the mode of writing of record data, data write signals generated based on the optimum write power (special power) and the corresponding special strategy to the irradiating unit 3.
<Operations of the Information Recording Apparatus>
Next, operations of the information recording apparatus 100 according to this embodiment will be described hereinafter with reference to
First, the operations of the data recording method of the information recording apparatus 100 will be described with reference to
The information recording apparatus 100 carries out a visible-image forming process that performs the DC writing on a data recording surface of the optical disc 1 to form a preset character and/or an image thereon in step S100. Next, the information recording apparatus 100 performs a record-data recording process that records record data over the entire of the data recording surface including a visible-image area on which the preset character and/or image has been formed in step S200. Note that the visible-image forming process in step S100 and the record-data recording process in step S200 can be sequentially performed in a series of processes. Moreover, the visible-image forming process in step S100 can be performed first, and after a preset period has elapsed since the completion of the visible-image forming process, the record-data recording process in step S200 can be performed.
The visible-image forming process in step S100 will be fully described hereinafter with reference to
The information recording apparatus 100 obtains the disc information of the optical disc 1 previously stored in the optical disc 1 mounted therein (step S110). For example, the disc information includes the manufacture, the model number, the type of the recording layer, the write strategy, and the like.
Next, the information recording apparatus 100 determines, based on the obtained disc information, a level of write power for the DC writing in step S120. Specifically, the information recording apparatus 100 retrieves one item of the plurality of items of DC write-power information d10 stored in the memory 10; the retrieved DC write-power information d10 corresponds to the obtained disc information (model number), thus determining the DC write power.
Next, the information recording apparatus 100 obtains the display-area information as position information associated with the area on which a visible image is to be formed in step S130.
Thereafter, the information recording apparatus 100 performs DC writing in accordance with the display-area information to thereby form a preset character and/or an image in step S140.
The record-data recording process in step S200 will be fully described hereinafter with reference to
The information recording apparatus 100 obtains the disc information of the optical disc 1 previously stored in the optical disc 1 mounted therein (step S210). For example, the disc information includes the manufacture, the model number, the type of the recording layer, the write strategy, and the like. Note that, if the disc information obtained in step S110 of the visible-image forming process has been stored in the information recording apparatus 100, the disc information stored in the information recording apparatus 100 can be used without the need to obtain the optical disc 1 again.
Next, the information recording apparatus 100 determines, based on the obtained disc information, a special strategy in step S220. Specifically, the information recording apparatus 100 retrieves one of the plurality items of special strategy information d20 stored in the memory 10; the retrieved special strategy information d20 corresponds to the obtained disc information (model number), thus determining the special strategy.
Next, the information recording apparatus 100 carries out the OPC based on the determined special strategy to thereby find and determine an optimum level of write power in step S230; the optimum level of write power is optimum for writing the record data into the optical disc 1.
Thereafter, the information recording apparatus 100 performs writing of the record data based on the determined optimum level of write power in step S240.
As described above, according to this embodiment, even if a visible image area has been formed on a data recording surface of the optical disc 1, it is possible to write record data over the data recording surface including the visible-image area in a same recording condition, and maintain excellent the recording characteristics of an area on which the record data has been recorded. As a result, even if overwriting of record data is carried out on the visible-image area, it is possible to prevent deterioration of the recording characteristics. In addition, it is possible to write record data under simple control without regard to the boundaries between the visible-image area and unrecorded areas.
Note that, in this embodiment, the information recording apparatus 1 stores therein the DC write-power information and the special strategy information d20, but the DC write-power information d10 and the special strategy information d20 can be stored in the optical disc 1. In this case, because the optical disc 1 stores therein the DC write-power information d10 and the special strategy information d20, which are most suitable for its model number, the information recording apparatus 1 can obtain the DC write-power information d10 and the special strategy information d20 stored in the optical disc 1.
In addition, in this embodiment, performing DC writing forms a visible image, but the visible-image forming method is not limited to the DC writing. For example, in place of the DC writing for outputting a signal with constant write power as illustrated in (a) of
In this embodiment, a same recording condition (the special recording condition) is used over the entire of an area on which record data is to be recorded, but different recording conditions can be selectively used.
In the data recording method according to this embodiment, the information recording apparatus 100 forms a visible image on a data recording surface of the optical disc 1, and thereafter, writes record data on a formed visible-image area, but the information recording apparatus 100 can perfume them in the reverse order. Specifically, the information recording apparatus 100 can write record data on a data recording surface of the optical disc 1, and thereafter, form a visible image on an area on which the record data has been recorded.
In this modification, because a level of the DC write power and a value of the special strategy are different from those used according to this embodiment, a level of the DC write power and a value of the special strategy need be stored.
For forming a visible image on an area on which record data has been recorded, the DC writing may affect on the recording characteristics of the area on which the record data has been recorded. Specifically, the DC writing may contribute to an imbalance between long marks and short marks in the area on which record data has been recorded. Thus, a special recording condition can be established with consideration of such an imbalance between long marks and short marks due to the DC writing. The inventors of this application has filed a patent application whose Publication is No. 2008-305485. This application discloses, after writing data on an area under a recording condition with the pulse width of a write signal for a preset mark, which is longer than an optimum pulse width for the preset mark, DC writing is carried out on the area on which the data has been recorded, making more excellent the recording characteristics of the data recorded area. Thus, using the disclosed principle can set the pulse width of a write signal for writing a shortest mark (3 T) in the special strategy to be longer than an optimum pulse width of a write signal for writing the shortest mark (3 T).
In order to carry out both the data recording method according to this embodiment and the data recording method according to this modification, the information recording apparatus 100 can be provided in the memory 10 with DC writing information d30 having two levels of DC write power (see
Note that running a program stored in the information recording apparatus 100 can carry out the operations of the information recording apparatus 100, and the program can be stored in a computer-readable storage medium, such as a ROM, a hard disk, a CD-ROM, a DVD-ROM, or the like, or can be distributed via a communication network.
The present invention is not limited to the embodiment set forth above, and the embodiment of the present invention can be deformed or modified within the scope of the present invention. Such deformations or modifications based on the embodiment can be within the technical range of the present invention.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2009/059130 | 5/18/2009 | WO | 00 | 11/4/2011 |
