JP4306288B2 - Visual information recording method on optical disk - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for writing information such as characters and pictures visible to the naked eye for identifying recorded contents of an optical disc on an optical disc.
[0002]
[Prior art]
There are various known principles for recording information on a thin film (recording film) by irradiating laser light. Among them, atoms such as phase changes (also called phase transitions) and photodarkening of film materials are caused by laser light irradiation. Those using the array change have the advantage that a double-sided disk structure optical disk or a multilayer optical disk having a plurality of information surfaces can be obtained by directly laminating two disk members together with almost no deformation of the thin film. Conventional optical disks such as CD-R, CD-RW, PD, DVD-R, DVD-RW, and DVD-RAM reproduce recorded information using a device incorporating a laser.
[0003]
However, since playback of recorded information requires a playback device that incorporates a laser light source in a normal optical disc, the contents recorded by the user on the optical disc must be confirmed unless the playback device plays back the optical disc. I could not.
[0004]
Regarding the method of recording the visual information on the optical disc, for example,
Japanese Patent Laid-Open No. 2003-16649 and the like will briefly describe an example of recording the visual information.
[0005]
An optical disc is a disc-shaped recording medium on which information that can be reproduced using a difference in reflectance is recorded or is recordable. The optical characteristics of a recording film by irradiating a laser beam modulated by recorded information, that is, Information is recorded using the change in reflectance, and information is reproduced using the difference in reflectance. In addition to the phase change material, an organic dye that can be erased by light irradiation / heating can be used for the recording film.
[0006]
FIG. 2 is a diagram showing the difference in reflectance between a recording mark portion and a non-recording portion of a typical optical disc recording film material, where the horizontal axis represents wavelength and the vertical axis represents reflectance. Rm is the reflectance of the recorded mark portion, and Rs is the reflectance of the unrecorded portion, that is, the space portion. Recording of information on a normal optical disc is performed by forming a recording mark by irradiating a laser beam along a track of the recording film. The recorded information is reproduced by reading the position of the recording mark or mark edge using the difference in reflectance between the mark portion and the space portion between the marks. The track width of the optical disk is about 0.3 to 1.6 μm, the mark length is about 0.1 to 5 μm, and the recording marks are extremely small. Therefore, the individual recording marks cannot be visually recognized with the naked eye.
[0007]
In this conventional example, paying attention to the fact that the reflectivity of the optical disc recording film material is greatly different in the visible region, connecting the amorphous region and drawing a large character or picture across multiple tracks on the recording film as a figure, A figure writing method has been proposed in which an amorphous region constituting characters and pictures and a surrounding crystallized region are visually recognized by the difference in reflectance.
[0008]
That is, a visible figure is written by a set of element regions (pixels: area 0.01 mm × 0.01 mm or more) whose average reflectance is changed by 5% or more from the background region at any visible wavelength.
[0009]
The figure includes a picture, a character, a symbol, and the like. Here, the background area refers to an area other than the element area, that is, an area serving as a background of a visually recognizable graphic formed by a set of element areas.
[0010]
[Problems to be solved by the invention]
However, in the above-described conventional example, the recording portion of the visual information is recorded with a modulation code different from that of the recording portion of a normal optical disk, so that there is a problem that tracking or focus is lost during reproduction by a conventional optical disk reproducing apparatus. There was a case. Further, there is a problem that the contrast of the visual information is insufficient.
[0011]
An object of the present invention is to provide a method for recording visual information for identifying recorded contents on an optical disc that can reproduce recorded information by a conventional recording / reproducing apparatus.
[0012]
[Means for Solving the Problems]
In order to achieve the object of the present invention, the following means were used.
(1) Recording / displaying on the optical disc is performed by at least modulating the visible information including at least the index information indicating the recording content of the optical disc or the identification information of the optical disc, and the arrangement or arrangement density of the recording marks on the optical disc.
[0013]
This makes it possible to record and display visible information on a conventional optical disk medium using a normal laser beam used for recording and reproduction, thereby improving the usability of the optical disk and increasing the application range. .
[0014]
In particular, the visual information may be related information of user information recorded on the optical disc, that is, index information. When the index information is recorded / displayed as visual information, the management of the optical disc becomes easy and the usability is improved. In particular, since cameras and video recorders use a large number of optical disks, there is an advantage that a large number of disks can be easily identified. It is convenient to automatically record calendar information such as recording date and time, disc volume label, and the like as index information that can be viewed. In the case of a camera, the disk volume label is not normally specified by the user, so it is desirable to manage it using date information or the like. Of course, the index information is not limited to character information, and image information such as thumbnails may be recorded.
(2) The visual information is arranged in an area different from the user information recording area of the optical disc.
[0015]
As a result, recording / reproduction can be performed without affecting the recording / reproduction of the user information. Therefore, it becomes easy to record the index information while maintaining compatibility with the conventional recording / reproduction apparatus.
[0016]
As a method of recording in a different area from the user recording area, for example, there is a method of recording in a lead-out area or a lead-in area. In this case, it is possible to arrange the visual information without depending on the host or application that controls the recording / reproducing apparatus.
[0017]
As another method, there is a method of preventing a user from using a part of the original user area as a system area by securing a special file area for recording visual information. In this method, there is a merit that a wider area can be used for visual information display, but there is a demerit that the capacity that can be used by the user is reduced.
(3) A write-once optical disc was used as an optical disc for recording visual information.
[0018]
A write-once optical disc generally has a high reflectance and a high visibility of visual information, and is suitable for recording / displaying index information.
In this case, the visual information is preferably recorded at the same time as the “finalization process” for recording the lead-out area and the lead-in area.
Since user information cannot be additionally written after finalization, the index information reflecting the contents of the disc can be surely recorded by recording and printing the index information at the time of finalization.
(4) The optical disc has a filter layer that transmits 90% or more of light used for recording / reproduction and has absorption for visible light having a wavelength other than that used for recording / reproduction on the optical reproduction side of the recording layer. The filter layer has at least a wavelength region in which the absorption rate of the absorption is at least 50% or more in a region of 350 nm or more and 650 nm or less.
[0019]
This makes it possible to reduce light components having wavelengths that do not contribute to causing visual contrast in the visual information, and as a result, the visual contrast is improved. Further, since the filter layer almost transmits the recording / reproducing light, there is no adverse effect on the recording / reproducing characteristics.
[0020]
Instead of providing the filter layer on the optical disk as described above, the filter layer may be stored in a case having a filter function for storage or use. In this case, it is not necessary for light to pass through the case at the time of recording / reproduction, and therefore, it is sufficient that light used for recording / reproduction is transmitted approximately 50% or more. However, it is preferable to have at least a wavelength region of 50% or less as described above in the region of 350 nm or more and 650 nm or less for wavelengths other than the light used for recording and reproduction.
[0021]
The case may be a so-called jewel case for simple storage, or may be in the form of a cartridge that can be loaded into the optical disk drive as it is. The latter is more convenient to use, but the former has the advantage of improving the contrast of visual information with respect to existing media already on the market. Of course, it goes without saying that a conventional medium can be loaded in a cartridge type case.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
[Example 1]
FIG. 1 is an overall view of an optical disc according to an embodiment of the present invention. A DVD-R, which is a write-once optical disc having a diameter of 80 mm, has a user data area 101, a lead-in area 103, and a lead-out area 102 that are divided in the radial direction. Visible information 104 for identifying the recorded contents of the disc is recorded in the lead-out area.
[0023]
Here, when recording normal user data, as shown in FIG. 8A, the ratio of the space portion to the mark portion is substantially equal in the circumferential direction in the recording area of the recording film (5: 5). 8-16 modulation having a DC control function, which is distributed in the above), is employed, but when writing a visible picture or character, the distribution of marks on the recording film is divided into minute areas (pixels) over a plurality of tracks. To be modulated in macro. That is, visual information is recorded by modulating the ratio of the mark portion and the space portion in a plane. In order to facilitate visual recognition, in each pixel, an area in which the ratio of the mark part to the space part is 60% or more (FIG. 8B) and an area in which the ratio of the mark part to the space part is 40% or less (see FIG. 8 (c)) is preferably arranged corresponding to the visual information because the contrast becomes large. As shown in FIG. 1, the reflectance distribution is different in the visible wavelength region in the recording portion (mark portion) and the unrecorded portion space portion of the optical disc, and the “pixel” and the relative space of the mark are relatively large. Since a large number of “pixels” are arranged to form large visual information “pixels”, pictures and characters written with different hue / lightness / saturation can be visually recognized. The size of this pixel was 30 μm or more in diameter. 30 μm corresponds to the resolution of visual recognition with the naked eye. Here, the recording date and time of the user data on the disc is displayed as the visible information.
[0024]
Since such visible information is recorded in the form of recording marks on the disc, it can be recorded on a conventional optical disc medium using an optical head optical system equivalent to that mounted on a normal optical disc apparatus. Can be displayed. Of course, since the conventional optical disc apparatus does not have a function of recording visual information, a dedicated optical disc apparatus is required for recording visual information. However, the recorded visual information can be visually confirmed without using the optical disc apparatus. Therefore, a dedicated device for reproducing visual information is not necessary. Of course, in order to be able to confirm the visual information electronically, it is desirable from the viewpoint of simplicity of disc management that the contents equivalent to the visual information are recorded as digital information in the normal user area.
[0025]
This visual information is arranged in the lead-out area as shown in FIG. In the lead-out area, no light spot is irradiated during reproduction, so there is no problem even if a modulation code different from that used in normal recording is used. Actually, there is a possibility that a reproduction spot may be positioned in an area of about 100 μm at the boundary with the user area due to the eccentricity of the disc, etc. Therefore, in an area at least about 100 μm at the boundary with the user area From the viewpoint of compatibility, it is desirable not to record the visual information.
[0026]
FIG. 3 shows an example of a block diagram of the optical information recording apparatus of the present invention. A recording operation when an information recording medium is loaded in the apparatus of the present invention will be described. Light emitted from a laser light source 25 (wavelength of about 660 nm in DVD-RAM) that is a part of the head 2 is collimated into a substantially parallel light beam 22 through a collimator lens 24. The light beam 22 is irradiated onto the optical disk 11 through the objective lens 23 to form a spot 21, and then guided to the servo detector 26 and the signal detector 27 through the beam splitter 28, the hologram element 29, and the like. Signals from the respective detectors are added and subtracted to become servo signals such as tracking error signals and focus error signals, which are input to the servo circuit 33. The servo circuit controls the positions of the objective lens 31 and the entire optical head 2 based on the obtained tracking error signal and focus error signal, and positions the position of the light spot 21 in the target recording / reproducing area. The addition signal of the detector 27 is input to the signal reproduction block 41. The input signal is digitized by the signal processing circuit 42 after filtering and frequency equalization. The digitized digital signal is processed by the address detection circuit 44 and the demodulation circuit 43 to obtain address information and reproduction information.
[0027]
An operation at the time of recording user information in such an optical disc apparatus will be described. In response to an instruction from the host device (host) 70, the microprocessor 54 receives the recording data from the host 70 through the interface 71 and stores it in the memory 52. The microprocessor 54 positions the light spot 21 in the area to be recorded based on the reproduced address information, and at the same time, performs digital processing (encoding, DC control, 8-16 modulation) required for user data stored in the memory 52. After recording waveform conversion, the laser driver 51 is instructed to modulate and irradiate the laser to form a recording mark on the recording medium. Part of this digital processing is processed by a dedicated digital processing circuit (DSP) 53 in accordance with instructions from the microprocessor. The digitally processed user data is sent to the laser driver 51 through the visual information recording processing circuit 55. When the user data is recorded, the visual information recording processing circuit 55 does not perform any processing and the digital data from the DSP 53 is used as it is. It is sent to the laser driver 51.
[0028]
When recording the visual information, the microcomputer 54 instructs the visual information recording circuit 55 about the visual information to be recorded and the recording position, and the visual information recording circuit 55 calculates the track (radial position) from the reproduction address information. At the same time, the angle (circumferential position) is calculated from the rotation synchronization information (FG) obtained from the automatic position control means. Based on the radial position and the circumferential position, visual information is recorded at a position corresponding to each “pixel”. As described above, the visual information is recorded by modulation of the mark density (mark / space duty). The mark space duty is modulated by “modulating” the duty of the digital data sent from the DSP. . The apparatus of this embodiment has two types of modulation methods.
[0029]
The first is a method in which the duty of digital data is subtly “modulated” within a range of several percent. In this method, digital information itself is recorded as it is without being lost. It is used when displaying. The second is to add “change” to the digital data itself. When the mark duty is increased, the mark is uniformly extended by 1T or 2T. However, if the space before and after the mark becomes 2T or less as a result of increasing the length, the mark is not lengthened. According to this method, recording marks / spaces of 3T to 14T are normally used in 8-16 modulation, but the mark has a length of 3T to 16T, and the space is 3T to 12T. The average length of the mark and the space was 5T before the “change”, but after the “change”, the mark portion is about 6.2T and the space portion is about 3.8T. That is, the mark duty is about 62%. The same is true when the space portion is lengthened. In this case, the mark is uniformly shortened by 1T or 2T. However, when the mark length becomes 2T or less as a result of shortening, the mark is not shortened. The resulting mark has a length from 3T to 12T and a space from 3T to 16T. After the “change”, the average length of the mark and space is about 3.8T for the mark portion and about 6.2T for the space portion. That is, the mark duty is about 38%.
[0030]
Therefore, by using the second method, it is possible to “modulate” the mark density from 62% to 38%. Further, this change is performed in the same way in each “pixel” that is aligned in the circumferential direction and spans a plurality of tracks 12 in the radial direction.
[0031]
As a result, a pixel with a mark density of 62% and a pixel with a mark density of 38% can be formed, and the difference in mark density is visually recognized as bright and dark as described with reference to FIG. By arranging, visual information such as figures and characters can be arranged on the recording medium 11.
[0032]
Since the write-once type optical disc is used in this embodiment, the visual information is also of the write-once type. Therefore, the visual information (index) representing the disc contents is determined after all user data is recorded. By doing this, it becomes possible to display visual information representing the latest contents after recording the last user information as an index on the disc.
In a write-once optical disc DVD-R, data on the disc is recorded in the order of (1) user information (2) lead-out (3) lead-in as shown in FIG. The lead-out and lead-in are recorded at the time of finalizing processing after all user information has been recorded. Therefore, in this embodiment, the date / time information indicating the recording period of the disc is recorded as visible character information as described above in the lead-out portion at the time of finalization. Finalization is an indispensable process for write-once discs and is a relatively time-consuming process. By sharing the process, index information can be automatically recorded without making the user aware of it. . In addition, the lead-in recorded at the time of finalization is recorded over a radius of at least 1 mm. An area sufficient for recording character information is automatically secured, and since the lead-in is not a user area, the second method of “changing” digital information can be employed. Since the second method can increase the degree of modulation of the mark density, there is an advantage that a sufficient contrast can be obtained, and relatively fine information can be displayed. Of course, in the case of a system in which finalization is performed according to a user's instruction, it is possible to require the user to input label information at the time of finalization.
[0033]
Of course, the above-mentioned recording date and time can be used in combination with automatic recording. If the method of automatically recording the recording date and time is adopted by a camera or the like, there is an advantage that the management of the disk becomes easy.
[Example 2]
FIG. 5 shows an example in which the visual information is arranged in the user area. in this case,
From the viewpoint of compatibility with other playback systems, it is desirable to secure the “label information” area as a “system file” on the file system. In this case, since the system file is reserved as an area but is not accessed by the user, even if the label information is modulated by the second method using the recording apparatus of the first embodiment, no problem occurs. There are advantages. This method is effective when employed in a rewritable recording medium such as a DVD-RAM in which the size of the lead-out area is fixed and it is difficult to secure a sufficient label (index) area. In DVD-RAM, user data and address information for access and servo information are arranged completely separated, so even if processing that makes it impossible to "change" digital data and perform playback, it is still possible to access There is no hindrance. Therefore, in the method of this embodiment in which the label area is secured as a system area that does not need to be reproduced, it is easy to improve the contrast by increasing the degree of modulation of the mark density. For example, in the same way as in the above example, instead of using the 62% and 38% mark density areas as pixels, a mark density of about 70% area and 0% area, that is, an unrecorded area are mixed. It can be used as a “pixel” to improve visual contrast.
[Example 3]
A configuration in which visual information is recorded in the information area with a relatively low importance on the file system (meaning that a 1-bit error does not cause fatal damage to the system) by the first method of the first embodiment. did. When using mainly video recording, this method is effective in that the recording area of the entire disk can be used effectively and almost the entire area of the disk can be used as a visual information area. If the value is larger than a few percent, there is a risk that the reproduction of the important recorded information may be frustrated, so the contrast of the visual information cannot be increased. For this reason, the present invention is preferably applied to a medium having a large change in reflectivity such as a write-once recording medium.
[Example 4]
The contrast of visual information can be improved by using the medium shown in FIG. 6 instead of using the conventional optical recording medium. In FIG. 6, a recording layer 111 is laminated on a substrate 110, and a dummy substrate 112 is bonded to the opposite side of the substrate 110. A filter layer 113 is disposed on the light incident surface side (the lower side in the figure) of the substrate. This filter layer transmits almost 100% of light of the wavelength used for normal recording and reproduction (in the DVD medium of this embodiment, around 660 nm) and absorbs visible light of other wavelengths, that is, wavelengths from 600 nm to 350 nm. It has special characteristics. As such materials, there are various known materials such as a dye having an absorption edge near a wavelength of 600 nm, a semiconductor material having a band gap near a wavelength of 600 nm, and a metal / dielectric multilayer film using multiple interference. I won't mention it here. Figure of recording layer 2 As shown in the figure, the reflectivity of the recording mark part and the contrast of the space part are maximized near the wavelength of 650 nm, but the contrast is small in other visible wavelength ranges, for example, the reflectance is low in the short wavelength range of 400 nm. The relationship is reversed Roll is doing. For this reason, in the entire visible range, the difference in reflectance between the mark portion and the space portion is not so large. Therefore, in this example, a GaP-based semiconductor filter having characteristics as shown in FIG. 9 was used. This makes the contrast small Visible light in the region below 550nm absorbs almost 100% Is done. For this reason, the contrast of visual information improves dramatically. Since light having a wavelength near 660 nm used for recording and reproduction is transmitted almost 100%, there is almost no influence on recording and reproduction.
[Example 5]
In this embodiment, as shown in FIG. 7, a double-sided medium in which a recording layer 111 is laminated on a substrate 110 and bonded on both sides by an adhesive layer 115 is stored in a case 114. The double-sided medium itself in the case is a conventional medium. As shown in FIG. 10, this case 114 transmits about 80% of light having a wavelength used for normal recording / reproduction (around 660 nm in the DVD medium of this embodiment), and visible light having other wavelengths, that is, from a wavelength of 600 nm. It has the characteristic of having a large absorption at 350nm. In this example, colored polycarbonate was used for the case. This case looks red-orange visually. As shown in FIG. 1, the recording layer of the conventional recording medium has a characteristic that the reflectance of the recording mark portion and the contrast of the space portion are maximized near the wavelength of 650 nm, but the contrast becomes small in other visible wavelength regions. The reflectance relationship is reversed in the short wavelength range of 400 nm. For this reason, the difference in reflectance between the mark portion and the space portion is not so large when viewed in the entire visible range. However, when the optical characteristics of FIG. 10 of this embodiment are viewed through the case, the contrast is less than 500 nm. Visible light is almost absorbed, and the transmittance of light with a wavelength near 600-700 nm is large, so that the contrast of visual information is improved when viewed through the case.
[0034]
The method of this embodiment is very effective in that a conventional recording medium can be used as it is. Needless to say, this case may have a holder function and a cartridge function when the disk is loaded in the recording apparatus.
[0035]
The effects of the present invention are not limited to the above embodiments.
For example, a high-density optical disk that performs recording / reproduction with blue laser light instead of DVD may be used as the recording medium. In this case, when using a case or filter, it is necessary to match the wavelength characteristics with the laser light source. In other words, it is desirable to use a material having characteristics such that it substantially transmits light near 400 nm used for recording and reproduction and has a large absorption with respect to other visible light on the long wavelength side.
[0036]
Further, as the visual information, not the recording time but a serial number for organizing the disc and thumbnail image information may be automatically generated and displayed. When recording image information, it is desirable not to “modulate” “pixels” with binary values but to “mark gray” by modulating the mark density step by step. In the case of a portable camera, location information collected by GPS or the like in addition to time information may be automatically recorded and displayed. In this case, it becomes easier to organize the disk. In the case of a stationary recorder, the recording date / time channel information and the program name obtained by EPG (electronic program guide) may be automatically recorded and displayed as index information. In any case, disk management and organization becomes easy.
[0037]
As a recording method, there is a method of changing the average mark / space length in addition to the method of changing the mark density (duty) described above. In this case, although it cannot be directly seen as a bright and dark pattern, the contrast appears when the diffraction pattern when the disk is tilted is seen. That is, information can be recorded as a kind of “watermark”.
[0038]
【The invention's effect】
As described above, according to the present invention, a visible character or picture can be written on a conventional recordable or rewritable optical disc, so that it can be recorded / reproduced by a conventional device and recorded on the disc, index information Discs can be recorded in a visually identifiable form, making disc management and identification easy. Especially when using many discs of the same type, such as cameras and videos, manually label the discs. Since there is no need to write, the usability is improved.
[Brief description of the drawings]
FIG. 1 is an overall view of an optical disc according to an embodiment of the present invention.
FIG. 2 is a diagram showing optical characteristics of the optical disc of the present invention and a conventional example.
FIG. 3 is a block diagram of an optical disk drive apparatus of the present name.
FIG. 4 is a diagram showing the order of information recording according to an embodiment of the present invention.
FIG. 5 is a diagram showing an information arrangement according to one embodiment of the present invention.
FIG. 6 is a diagram showing a cross-sectional structure of an optical disc according to one embodiment of the present invention.
FIG. 7 is a view showing a cross-sectional structure of the optical disc and the case of the present invention.
FIG. 8 is a diagram showing the visual information recording principle of the present invention.
FIG. 9 is a graph showing optical characteristics of the filter layer of the present invention.
FIG. 10 is a diagram showing optical characteristics of the case of the present invention.
[Explanation of symbols]
11 ... Optical disc, 12 ... Track, 13 ... Recording mark, 14 ... Space, 2 ... Optical head, 21 ... Optical spot, 22 ... Optical beam, 23 ... Objective lens, 24 ... Collimator lens, 25 ... Laser 26 ... Detector , 27 ... detector, 28 ... beam splitter, 29 ... hologram element, 31 ... lens actuator, 32 ... position control means, 33 ... servo circuit, 34 ... motor, 41 ... signal reproduction block, 42 ... signal processing circuit, 43 ... Demodulation circuit, 44 ... Address detection circuit, 51 ... Laser driver, 52 ... Memory, 53 ... DSP, 54 ... Microprocessor, 55 ... Visual information recording control circuit, 70 ... Host, 101 ... User data area, 102 ... Lead-out, 103 ... Lead-in, 104 ... Visual information, 105 ... System file, 110 ... Substrate, 111 ... Recording layer, 112 ... Dummy substrate, 113 ... Filter layer, 114 ... Case, 115 ... Adhesive layer.

Claims (1)

A method for recording / displaying visible information on an optical disk by at least modulating the arrangement or arrangement density of recording marks on the optical disk, wherein the visual information is index information indicating the recorded contents of the optical disk or optical disk identification information Including at least
The optical disc is a write-once optical disc,
The optical disk has a filter layer that transmits almost 100% of light having a wavelength of about 660 nm used for recording / reproduction and absorbs visible light having a wavelength other than that used for recording / reproduction on the optical reproduction side of the recording layer. The method for recording visual information on an optical disk, wherein the filter layer absorbs almost 100% of visible light having a wavelength of 550 nm or less .

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