JP2002123983A - Optical information recording medium having visual water mark, and device and method for forming visual water mark - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk having a visual water mark, capable of simultaneously recording a signal and a water mark. SOLUTION: This optical information recording medium includes recessed information pits 5 carrying information signals and projected inter-pit lands 6 alternately recorded in a row. A recess 7 shallower than a pit is provided in the inter-pit land 6. The recess is formed based on a signal having a random signal added to a water mark pattern. Thus, an optical disk having a visual mark is characterized in that the collection of recesses 7 represents a visible pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical information recording medium such as an optical disk having a visible watermark, a visual watermark forming apparatus and a method of forming the same.

[0002]

2. Description of the Related Art Conventionally, as a method for making characters and pictures macroscopically visible on a recording surface of an optical disk, a pit for display is provided between recording tracks as disclosed in Japanese Patent Application Laid-Open No. 8-167170. There is known a technology for providing character information and the like by embodying character information.

The method disclosed in Japanese Patent Publication No. 10-502203 discloses a method of recording pits with a laser recording device, applying a mask of characters or pictures, and exposing the photoresist again. A method for changing the height of the land is disclosed.

[0004]

However, in the method disclosed in Japanese Patent Application Laid-Open No. 8-167170, a plurality of laser beams of a recording device are provided, each of which irradiates the glass master with high accuracy, and a signal recording modulator and a pattern recording device. Modulators are separately required and cannot be realized with a normal glass master recording apparatus, and a new glass master recording apparatus needs to be manufactured. In addition, DVD, which is a recent medium, has a high density of pits, and it is technically difficult to insert another pit accurately between pit rows.

In the method disclosed in Japanese Patent Application Laid-Open No. 10-502203, it is necessary to first form pits using a laser recording apparatus and then expose the pattern using another apparatus. This increases the number of glass master manufacturing steps and exposes the pattern. In such a case, it is difficult to control the depth of the pits, and there is a problem that reproduction is hindered if the pits are exposed too much.

Accordingly, an object of the present invention is to provide an optical information recording medium with a visual watermark, a visual watermark forming apparatus and a method for forming the same, which can simultaneously record a signal and record a watermark. I do.

[0007]

According to a first aspect of the present invention, there is provided an optical information recording medium in which concave pits and convex lands for carrying an information signal are alternately recorded in rows. In the land between the pits, a concave portion shallower than the pit is formed, the concave portion is a watermark pattern is formed at random, the aggregate of the concave portion represents a visible pattern. This is an optical information recording medium with a visual watermark featured.

According to a second aspect of the present invention, in the optical information recording medium with a visual watermark according to the first aspect, the optical information recording medium has a disk shape. Medium.

According to a third aspect of the present invention, in the optical information recording medium with a visual watermark according to the first aspect, the optical information recording medium has a card shape. Medium.

According to a fourth aspect of the present invention, there is provided a visual watermark forming apparatus for an optical information recording medium, comprising: means for converting a pit signal into a pit forming signal corresponding to a predetermined pit depth; Means for converting a mark signal into a watermark forming signal for forming a watermark on a land corresponding to a water mark depth shallower than the pit depth; synthesizing means for synthesizing the pit forming signal and the watermark forming signal; It is a visual watermark forming apparatus provided with:

According to a fifth aspect of the present invention, in the method for forming a visual watermark on an optical information recording medium, a pit signal is converted into a pit forming signal corresponding to a predetermined pit depth, and a watermark signal is added with a random signal. Is converted into a watermark forming signal for forming a watermark on a land corresponding to a water mark depth shallower than the pit depth, and the pit forming signal and the watermark forming signal are combined, based on the combined signal. This is a method for forming a visual watermark, characterized in that recording is performed using modulated laser light.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an enlarged perspective view showing a part of a recording area of an optical disc according to an embodiment of the present invention. FIG. 1 shows the transparent substrate 4a immediately after molding, and does not show a reflective film, a protective film, and the like. Further, the same form is applied to the glass master after the development processing.

As shown in FIG. 1, for example, a first recording track 1, a
The second recording track 2 and the third recording track 3 are formed with the inter-track land 8 interposed therebetween.

On the first recording track 1, signal pits 5, which are information pits for recording program information such as music, and inter-pit lands 6 between the signal pits 5 are alternately arranged. They are formed in rows.

The second recording track 2 has a signal pit 5
In the land portion between the pits between the signal pit 5 and the signal pit 5, a concave portion 7 which is a watermark having a depth d of 1/10 of the depth D of the signal pit 5 is formed.

The third recording track also has a depth d, for example, 1/10 of the depth D of the signal pit 5 in the land between pits between the signal pits (not shown).
A concave portion 7 serving as a watermark is formed.

The recesses 7 are arranged so that an aggregate thereof represents a visual pattern as a visual watermark pattern.

FIG. 2 is a plan view of the optical disc on which the visual watermark pattern is formed.

As shown in FIG. 2, the aggregate of the recesses 7 represents a visual watermark pattern 10 (“A” in the figure). In this case, as shown in FIG. 2, even when the concave portions 7 serving as the watermarks are gathered inside the character line of the pattern "A" or the patterns including the concave portions 7 are gathered, there is no watermark outside the character line 11. Alternatively, a watermark may be collected or a pattern including a watermark may be collected outside 11 of the character line of pattern "A" so that no watermark is present inside the character line.

FIG. 3 shows a signal waveform sent to the optical modulator for controlling the writing laser light, and shows a comparison between the writing signal waveform of the signal pit portion and the writing signal waveform of the watermark portion.

As shown in FIG. 3, in the write signal waveform 12 in the signal pit portion, 5a indicates the intensity required to form the signal pit 5 to a predetermined depth, and 7a indicates a watermark which is shallower than the signal pit. Shows the strength required to form the recess 7 for use at a predetermined depth. 6a corresponds to the land 6 between pits.

FIG. 4 is a block diagram showing a visual watermark forming apparatus for simultaneously forming signal pits and watermark pits.

As shown in FIG. 4, the visual watermark forming device includes an EFM signal generating device 21, a watermark pattern generating device 22, and a random signal generating device 22a for adding a random signal to the watermark pattern generating device 22. , A watermark generation circuit 24 for synthesizing a recording signal from the EFM signal generator 21 and a watermark signal to which a random signal has been added from the watermark pattern generator 22, and an optical modulation (not shown) for inputting the synthesized signal Device 23 having a laser device to which a drive signal for writing is supplied from a recorder
It is comprised including. Note that as the laser device, a laser capable of exposing a photoresist, such as an argon laser, a He—Cd laser, a krypton laser, or a semiconductor laser, can be used.

In the present embodiment, the EFM signal generator 21 generates a CD signal based on a signal from a music source or a signal from a sub-coding signal generator (not shown).

The watermark pattern generator 2
2 generates a watermark signal that forms a visible pattern. Ideally, the lowest frequency of the signal generated from the random signal generator 22a is set to be shorter than the longest pit length of the medium on which the watermark is recorded. If the time constant of the data slicer is determined by the media, the lowest frequency of the random signal is set so as to be higher than the cutoff frequency on the high frequency side.

The watermark generation circuit 24 has an EFM
The recording signal from the signal generator 21 and the watermark signal to which the random signal from the watermark pattern generator 22 has been added are synthesized.

This watermark generation circuit 24 has an E
Non-invert buffer 27 for adjusting the delay amount of the CD signal input from FM signal generator 21 and inverter 32 for inverting the output of non-invert buffer 27
, A pit depth adjusting multiplier 34 for adjusting the output from the inverter 32, and a watermark signal to which a random signal from the watermark pattern generating device 22 has been added. ), An inverter 31 for inverting the output of the invert buffer 25, a multiplier 33 for adjusting the depth of the watermark pattern for adjusting the input from the inverter 31, and a multiplication for adjusting the pit depth. Output from the multiplier 34 and the multiplier 33 for adjusting the depth of the concave portion.
And an adder circuit 36 for adding the output from the adder 36 in an analog manner. The output from the adder circuit 36 is input to the recording device 23. In the figure, 28 is a ground, and 29 is a pull-up resistor.

The CD signal is a signal obtained by adding a code related to a signal pulse to a train of quantized pulses or rearranging the codes and then performing EFM modulation. XN of the pit depth adjusting multiplier 34 is a pit depth adjusting coefficient, and the properties (physical properties, sensitivity) of the photoresist,
It is appropriately determined according to the sensitivity of the laser beam and the like.

The multiplier 33 for adjusting the depth of the concave portion 33
n is a depth that can form a recess required to form a visible watermark (ie, the lower limit of the depth of the recess) and does not affect the reproduction of signal pits (ie, the depth of the recess). (Upper limit) is set within a range in which the concave portion can be formed.

The optical modulator provided in the recording device 23 receives the signal synthesized by the watermark generation circuit 24 and modulates the laser light for writing. As the optical modulator, for example, an electro-optical element, an acousto-optical element, or the like can be used.

Incidentally, even if the inverter immediately after the EFM signal generator 21 in FIG.
It can be used when the RZI signal is used as a recording signal.

FIG. 5 is a diagram showing each signal waveform in FIG. 5A shows a waveform of a watermark signal to which a random signal is added, FIG. 5B shows a waveform of the recording signal in FIG. 4B, and FIG. 5C shows an inverted recording signal obtained by inverting the recording signal. (D) shows the waveform of the intermediate processing signal obtained by inverting the signal limited by the watermark,
(E) shows a level change (in this case, almost no change)
(F) shows the waveform of the intermediate processed signal whose level has changed (in this case, the level has decreased), and (g) shows the waveform of the output signal input to the optical modulator. Show.

In the output signal of FIG. 5 (g), 5a corresponds to a pit of the recording signal, 7a corresponds to a concave portion of the watermark, and 6a corresponds to a land.

According to the above embodiment, the pit of the recording signal and the concave portion of the watermark can be formed simultaneously by the same laser.

That is, in the manufacture of an optical disk, a signal for a visual watermark is added to a modulation signal to be sent to a recording laser light modulator of a glass master disk recording device, and a pit is added in addition to a normal pit (hole) and land (hill). A new shallow recess (1/3 of the pit depth) is added to the land between pits in the row.
Watermarks can be sufficiently visually observed at about 10. The depth can be set freely within a range that does not affect reproduction. ) To form a watermark (watermark) that forms a character or picture that can be visually confirmed.

Further, since a random signal is added to the watermark pattern and the signal is recorded as a watermark pattern, the disc reproduction signal when the watermark is formed without adding the random signal shown in FIG. (A) of the asymmetry (shift d between the center of the eye and the center of the amplitude of the eye pattern) generated in FIG.
As shown in FIG.

The present invention relates to an optical disk (LD, CD, DV
D) can be applied to any device having a pit formed therein, and is particularly suitable for a DVD that can be expected to spread in the future.

First, in order to form a pattern on an existing pit without newly providing a pit row between pits, the present invention can be realized only by modifying a part of a laser recording apparatus currently used.

Since the pattern is formed simultaneously with the laser recording, the glass master can be directly sent to the metal master manufacturing process after the development processing without any additional work.

Since the watermark signal can be directly applied to the modulator of the laser recording apparatus, the ratio of the depth of the pit and the depth of the groove for the watermark can be controlled by the signal ratio.

In the above embodiment, the entire land portion between adjacent pits in the pit row is formed as a concave portion.
A part may be a concave portion.

In the above embodiment, the case where the pit row of the recording track is a spiral disk has been described. However, the present invention can be easily applied even if the pit row is concentric.

Further, in the above embodiment, the case of the disk shape was described, but the disk shape may be used.
The present invention can be easily applied even if the pit row is formed in a straight line.

The present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the gist of the present invention.

[0045]

As described above, according to the present invention, the pits of the recording signal and the concave portions of the watermark can be formed simultaneously by the same laser, and the fluctuation of the eye pattern, in particular, the asymmetry can be reduced. And the occurrence of a reading error can be prevented.

That is, the pit of the recording signal and the concave portion of the watermark can be formed by a common laser and optical modulator.

Further, since a watermark is formed on a land on the pit row, it is suitable for high-density recording of a DVD or the like.

Furthermore, since it is not necessary to perform re-exposure to form a watermark pattern, the pit depth can be easily controlled without increasing the number of glass master production steps.

[Brief description of the drawings]

FIG. 1 is an enlarged perspective view showing a part of a recording area of an optical disc according to an embodiment of the present invention.

FIG. 2 is a plan view of an optical disc on which a visual watermark pattern according to an embodiment of the present invention is formed.

FIG. 3 is a diagram showing a signal waveform sent to an optical modulator that controls a writing laser beam according to an embodiment of the present invention.

FIG. 4 is a block diagram illustrating a visual watermark forming apparatus for simultaneously forming signal pits and watermark pits according to an embodiment of the present invention.

FIG. 5 is a diagram showing signal waveforms in FIG.

6A and 6B are diagrams showing asymmetry generated in a disk reproduction signal, in which FIG. 6A shows a case where a random signal is added to the watermark pattern according to the present invention, and FIG.
Is a case where a random signal is not added to the watermark pattern.

[Explanation of symbols]

 Reference Signs List 5 signal pit 6 land between pits 7 concave portion 21 EFM signal generating device 22 watermark pattern generating device 22a random signal generating device 23 recording device 24 watermark generating circuit

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Claims (5)

[Claims] 1. An optical information recording medium in which concave pits and convex lands carrying information signals are alternately recorded in a row, recesses shallower than the pits are formed in lands between the pits. An optical information recording medium with a visual watermark, wherein the concave portions are formed by randomly forming a watermark pattern, and the aggregate of the concave portions represents a visible pattern. 2. The optical information recording medium with a visual watermark according to claim 1, wherein the optical information recording medium has a disk shape. 3. The optical information recording medium with a visual watermark according to claim 1, wherein the optical information recording medium has a card shape. 4. A visual watermark forming apparatus for an optical information recording medium, comprising: means for converting a pit signal into a pit forming signal corresponding to a predetermined pit depth; A visual watermark comprising: means for converting a watermark forming signal for forming a watermark on a land corresponding to a shallow water mark depth; and synthesizing means for synthesizing the pit forming signal and the watermark forming signal. Forming equipment. 5. A method for forming a visual watermark on an optical information recording medium, wherein a pit signal is converted into a pit forming signal corresponding to a predetermined pit depth, and a watermark signal to which a random signal is added is watermarked to a depth smaller than the pit depth. Convert to a watermark formation signal that forms a watermark on the land according to the mark depth,
A visual watermark forming method, comprising: synthesizing the pit forming signal and the watermark forming signal; and recording with a laser beam modulated based on the synthesized signal.