JPS6361199B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an optical recording medium formed of a film that is blackened by heat, such as a discharge polymerized film, a sputtered film, or a vapor-deposited film, and an optical recording medium formed by using this recording medium. The present invention relates to a recording track having optical contrast and an optical recording method for recording information.

The heat mode recording method, which utilizes the thermal effect of light such as a laser beam, has features such as no deterioration over time and the ability to perform additional recording in real time. Conventionally, recording media for this type of optical recording are:
A recording layer formed with a dye and a binder on a substrate (for example, US Pat. No. 1,117,419),
Media that use a metal thin film, metal oxide or chalcogenite glass layer as the recording layer (e.g. ML,
Venene “Electron, Ion and Laser Beam Tech
"11th Symposium Record (1969),
Electronics magazine 1968, 3rd, 18th issue p.50, Japanese Patent Application Publication No. 1973
-46317) is known.

However, these recording media have disadvantages in that they require high energy for recording, require a high-output light source such as a large Ar laser, and a modulation polarizer. In order to overcome these drawbacks, we have developed highly sensitive optical recording materials that can be applied to semiconductor lasers that are small and electrically easy to modulate, and have also devised medium configurations such as multilayer structures to improve the signal strength. Attempts have been made to obtain recording media with excellent noise-to-noise ratio, recording stability, ease of handling, and the like.

In order to improve the information density and the writing/reading speed of such optical recording media, it is effective not only to make the recording pits smaller, but also to provide tracks in the recording section. Also, the presence of recording tracks makes it easier for write/read heads to follow. Therefore, as a method for mechanically providing recording tracks, there is a grooved trace method used in the record disc method, but this method is difficult for random access recording and reproduction. Therefore, it has been desired to develop a highly sensitive optical recording medium and recording method in which optical recording tracks can be easily provided.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical recording medium capable of eliminating the above-mentioned conventional drawbacks, forming a recording track having optical contrast, and recording information pits on the recording track.

Another object of the present invention is to easily provide a recording track having optical contrast on an optical recording medium, and then to place information pits on the recording track, in order to solve the above-mentioned conventional problems. The object of the present invention is to propose an information recording method for an optical recording medium that can improve recording sensitivity.

The optical recording medium of the present invention has a substrate, a recording layer made of a film that is blackened by heat is deposited on the substrate, and the recording layer is irradiated with track recording light having an energy density necessary for blackening. A blackened striped recording track is formed on the track recording light irradiated area, and by irradiating the information pit recording light with a higher energy density than the track recording light onto the recording track, the information pit recording light irradiated area is melted and evaporated. The invention is characterized in that the information pit can be recorded.

In the optical recording method of the present invention, a recording track pattern to be recorded is scanned on an optical recording medium having a recording layer formed of a film that is blackened by heat using track recording light having an energy density necessary for blackening. ,
A striped recording track with optical contrast is formed by blackening along the pattern, and then recording is performed using an information pit recording light pulse having a higher energy density than the track recording light while making the write/read head follow the recording track. It is characterized by recording information pits by melting and evaporating the recording layer on the track.

Hereinafter, the invention will be explained in detail with reference to the drawings.

FIG. 1 shows an example of a medium used for recording according to the present invention, where 11 is a substrate, and 12 is a discharge polymerized film or a sputtered film as a film that is blackened by heat. As the substrate 11, a glass or transparent plastic plate can be used. In the discharge polymerized film or sputtered film 12 which is blackened by heat, the thin film itself has the property of absorbing recording light.

In the present invention, a recording track pattern to be recorded is first scanned onto the medium using recording light of low energy density. This recording light causes the thin film 12 to undergo a blackening phenomenon, and as shown in FIG. 2, tracks 23 having a stripe-like optical contrast are formed on the medium. When recording such a track 23, recording light having a lower energy density than the recording light of the information pit 24 is scanned at a low speed. As a result, energy several times the recording threshold of the information pit 24 is applied to the optical recording medium, but since the amount of energy applied per unit time is small, phenomena such as sublimation and evaporation do not occur in the medium. At first, only blackening occurs, and only striped tracks 23 blackened by heat are formed. Due to the generation of such striped contrast, the recorded track portion can have a higher absorption coefficient than the unrecorded portion.
During the following recording of the information pits 24, the recording sensitivity of the information pits 24 on the recording track 23 is increased. Note that the blackening phenomenon used in track recording is based on changes in the properties of the thin film, and is not accompanied by geometric changes such as surface shape.

Next, track 2, which is blackened in stripes,
3, information pits 24 are recorded by light pulses. As the information pit recording light in this case, pulsed light having a higher energy density than the track recording light described above and an extremely short duration is used. The medium thin film irradiated with pulsed light sublimates, evaporates or melts, forming small pore-like pits 24. This information pit 24 has a significant difference in transmittance or reflectance with respect to its surrounding parts.

FIG. 3 shows the optical contrast obtained in the process of recording information according to the present invention in a transmitted light readout mode. 31 shows the optical contrast of the unrecorded optical recording medium, 32 shows the optical contrast of the optical recording medium after the tracks 23 are recorded, and 33 shows the optical contrast of the optical recording medium after the pits 24 are written.

FIG. 4 shows another example of the medium used for optical recording of the present invention, where 41 is a substrate, and 42 is a substrate 41.
The reflective layer 43 formed on the reflective layer 42 is a discharge film or a vapor deposited film, and 44 is a protective layer deposited on the film 43. As the substrate 41, a glass plate, a plastic plate, an aluminum plate, a ceramic plate, etc. can be used.

FIG. 5 shows the formation state of tracks and pits recorded on the recording medium shown in FIG. 4, where 53 is a recorded track portion;
Reference numeral 4 indicates recording pits, each of which is formed as described above.

FIG. 6 shows the optical contrast in the reflected light readout method obtained in the process of the optical recording method of the present invention. 61 shows the optical contrast of an unrecorded optical recording medium, 62 shows the optical contrast after track recording, and 63 shows the optical contrast after pit writing.

In addition, in a reflective readout optical recording medium, even if an optical recording medium with a non-reflective structure formed by interposing an optical interference layer between the recording layer 43 and the reflective layer 42 is used, the information recording method according to the present invention can be applied. Can be used.

The principle of reading tracks and information pits recorded according to the present invention is as follows.

In the transmission readout type, the recorded optical recording medium has the optical contrast 33 shown in FIG. The information pit 24 is read out by operating to obtain the amount of transmitted light.

Since the reflective readout type has the optical contrast 63 shown in FIG. 6, the tracking servo of the track 53 operates to obtain the minimum amount of reflected light in the surplus portion of the track outside the width of the information pit 54. 54 is read out.

Next, FIGS. 8 and 9 show the recording state of information in the track direction on a recording medium on which information is recorded according to the present invention. FIG. 8 shows an example of a reflective light readout type recording medium, where 81 is an unrecorded portion, 82 is a track recording section, and 83 is an information recording section. The first pit block 84 in the track direction in the track recording section 82 is a heading information pit in which identification information of the track itself is recorded. Information to be recorded following this information pit 84 is written in an information pit 85. There is. 9th
The figure shows an example of a transmitted light readout type recording medium, where 91 is an unrecorded part, 92 is a track recording part,
93 indicates an information recording section. The first pit block 94 in the track direction in the track recording section 92 is a heading information pit in which identification information of the track itself is recorded. Information to be recorded following this information pit 94 is written in an information pit 95. There is.

Next, a specific example of the recording medium used in carrying out the method of the present invention will be described.

Example 1 Using glass as the substrate, 1x _CS2 gas
A high frequency discharge of 13.56 MHz was applied to the electrode in a container introduced with 10 ^-2 Torr. Its discharge is the discharge power
The test was carried out for 10 minutes at 120W, substrate temperature 50°C, and gas flow rate 10c.c./min. During this discharge, at a deposition rate of 1.5 Å/sec,
When Te was deposited, the film thickness containing Te was approximately 0.2μ.
A thin film of m was formed.

The absorption spectrum of the thin film thus obtained before recording was as shown by curve a in FIG. 7.
Next, this thin film was heated to blacken it. The absorption spectrum of the blackened area after recording was as shown by curve b in FIG. As can be seen from FIG. 7, it was confirmed that good track recording with high optical contrast could be performed by the track recording operation using laser beam heating. In fact, power 0.6
mW semiconductor laser light (wavelength 830nm) about 100m
Tracks could be recorded by irradiating with J/cm ² . Output 6 on the track recorded in this way.
mW semiconductor laser light pulse (1.2 x 2.0 μm diameter)
When irradiated with , it was possible to record information pits with a pulse duration of 100 ns. This was a sensitivity of approximately 30 mJ/cm ² when converted into energy density. The sensitivity when directly recording information pits in locations other than the recorded tracks was equivalent to approximately 40 mJ/cm ² .

Example 2 CS ₂ was deposited on an acrylic substrate under the same conditions as Example 1.
A high-frequency discharge was performed by introducing gas. During the discharge, Bi was deposited at a deposition rate of 1.4 Å/sec to form a thin film containing Bi with a thickness of about 0.2 μm. When measuring the reflected light of this thin film, at a wavelength of 830 nm, approximately
It was 30%. Tracks were recorded on this medium in the same manner as in Example 1. Due to the blackening, the reflectance on the track increased to 50%. Furthermore, information pits were recorded using laser pulses in the same manner as in Example 1. The reflectance decreased to 5% due to melting and evaporation of the recorded portion. The sensitivity of track recording is 100mJ/cm ² ,
The sensitivity of the information bit was 50 mJ/cm ² .

Example 3 A glass plate was used as the substrate, and Al was used as the reflective layer.
was deposited to a thickness of approximately 5000 Å. On top of this, a discharge polymerized film of CS ₂ was formed to a thickness of 3000 Å, and then Example 1
Similarly, a CS ₂ discharge polymerized film containing Te is approximately 100 Å thick.
It was formed to a film thickness of . As a result, the optical recording medium has a non-reflection structure that utilizes multiple interference, and has a wavelength of 830n.
The reflectance at m was about 20%. Tracks were recorded on this optical recording medium using a semiconductor laser beam with a wavelength of 830 nm and a power of 0.6 mW. By recording on such a track, the reflectance on the track was reduced to 5% or less, and the recording sensitivity of the track was 50 mJ/cm ² . Next, information pits were recorded on the track.
In that case, the wavelength is 830 nm, the beam diameter is 1.2 x 2.0 μm,
When using a semiconductor laser with a power of 6mW, the duration
Recording was possible with a pulse of 15 nsec. This had a sensitivity of about 5 m/Jcm ² in terms of energy density.

Example 4 Using a glass plate as a substrate, targeting chalcogenite glass with a composition of As ₈ Te ₇₅ G ₁₇ , introducing Ar into a container at 10 ^-2 Torr and performing sputtering at a high frequency of 13.56 MHz to prepare the substrate. above
A thin film of chalcogenite glass having a composition of As ₇ Te ₇₇ G ₁₆ was formed to a thickness of about 2000 Å. Using this as an optical recording medium, tracks were recorded using a semiconductor laser beam with a wavelength of 830 nm and a power of 1 mW. The sensitivity of track recording was 300 mJ/cm ² . Furthermore, on this track, a beam with a wavelength of 830 nm and a beam diameter of 1.2 x 2.0 μm,
Information pits were recorded using a semiconductor laser with a power of 6 mW. The recording sensitivity of the information pit is approximately 100m.
It was J/ ^cm2 . The sensitivity is approximately 200 when recording information pits directly in a location other than the recorded track.
It was mJ/ ^cm2 .

Example 5 Using a glass plate as a substrate and targeting chalcogenite glass having a composition of Te ₈₀ Ge ₁₄ Sb ₃ S ₃ , sputtering was performed in the same manner as in Example 4.
A thin film of chalcogenite glass having a composition of Te ₈₁ Ge ₁₅ Sb ₂ S ₂ was formed on a substrate to a thickness of about 2000 Å.
When tracks were recorded on this optical recording medium using a semiconductor laser beam in the same manner as in Example 4, a track recording sensitivity of 300 mJ/cm ² was obtained. Furthermore, when information pits were recorded in the same manner as in Example 4, the sensitivity was 100 mJ/cm ² .

Example 6 A glass plate was used as the substrate, and Al was used as the reflective layer.
was deposited to a thickness of approximately 5000 Å. On top of this, a discharge polymerized film of CS ₂ was formed to a thickness of 2800 Å, and further Example 1
Similarly, about 100% of the discharge polymerized film of CS ₂ containing Te was
The film was formed to a film thickness of 1.5 Å. As a result, the optical recording medium has a non-reflective structure that utilizes multiple interference, and the wavelength
The reflectance at 750 nm was less than 5%. wavelength
The reflectance at 830 nm was about 20%. Tracks were recorded on this optical recording medium using a semiconductor laser with a wavelength of 750 nm (beam diameter 3.0 mmφ, power 1 mW). The recording sensitivity was 50 mJ/cm ² .
As a result, the reflectance of the track portion at a wavelength of 750 nm increased to approximately 20%, but the reflectance at a wavelength of 830 nm decreased to less than 5%. Next, a semiconductor laser with a wavelength of 830 nm (beam diameter 1.2 ×
Information pits were recorded with pulsed light using a beam of 2.0 μm and a power of 6 mW. Recording was possible with a pulse duration of 15 nsec. This had a sensitivity of about 5 mJ/cm ² in terms of energy density.

Example 7 Using glass as a substrate, styrene monomer was made into a gas and introduced at 1×10 ^-2 Torr in a container.
A high frequency discharge of 13.56MHz was applied to the electrode. The discharge power is 120W, the substrate temperature is room temperature, and the gas flow rate is
It ran for 10 minutes at 15c.c./min. 1.5Å/during this discharge
When Te was deposited at a deposition temperature of sec, a thin film containing Te with a thickness of about 0.2 μm was formed. this
Wavelength of Te-containing styrene plasma polymerized film
Approximately 830nm semiconductor laser light with 0.6mW power
Tracks were recorded by irradiating with 100 mJ/cm ² . When this track was irradiated with a pulse of semiconductor laser light (1.2 x 2.0 μm diameter) with a power of 6 mW, information pits could be recorded with a pulse duration of 150 nsec. This is approximately 45 in terms of energy density.
The sensitivity was mJ/cm ² .

As explained above, according to the optical information recording method for an optical recording medium according to the present invention, a track having optical contrast can be easily produced, and the recording sensitivity of information pits on the recorded track can also be improved. I can do it. That is, according to the present invention, a track can be formed on an optical recording medium without changing the geometric shape, so that it is possible to easily randomly access each point on the recording medium using such a track when reading or writing information. It becomes possible to do so.

Further, according to the present invention, the sensitivity for recording information pits on recorded tracks is improved, so information can be recorded at a higher speed, and at the same time, recording errors such as exposure to areas other than the track areas can be reduced. be.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an example of the structure of the optical recording medium of the present invention, FIG. 2 is a perspective view showing the state in which tracks and information pits are recorded on the optical recording medium shown in FIG. 1 according to the present invention, and FIG. FIG. 4 is a sectional view showing another example of the optical recording medium of the present invention, and FIG. 5 is a diagram showing the optical contrast of the recorded state of the transmitted light readout type. FIG. FIG. 6 is a perspective view showing the state in which information pits are recorded. FIG. 6 is a diagram showing the optical contrast of the recorded state of reflected light readout type. FIG. and FIG. 9 is a diagram showing a state in which information is recorded on an optical recording medium according to the present invention. DESCRIPTION OF SYMBOLS 11...Substrate, 12...Discharge polymerized film or vapor deposited film containing a substance that blackens by heat, 23...Recorded track portion, 24...Recorded information pit, 31...Unrecorded medium Optical contrast, 32... Optical contrast of the recording medium after track recording, 33... Optical contrast of the recording medium after information recording, 41... Substrate, 42... Reflective layer, 43... By heat discharge polymerized film or vapor deposited film containing a blackening substance, 44...protective layer, 53
... Recorded track portion, 54 ... Recorded pit, 61 ... Optical contrast of unrecorded medium, 62 ... Optical contrast of recording medium after track recording, 63 ... Recording medium after information recording optical contrast, 81... unrecorded area, 82...
...Track recording section, 83... Information recording section, 84...
...Truck information pit (heading), 85
... Information recording pit, 91 ... Unrecorded section, 92
...Track recording section, 93...Information recording section, 94
...Truck information pit (heading), 9
5... Pit for information recording.

Claims (1)

[Claims] 1. A device having a substrate, a recording layer made of a film that is blackened by heat is deposited on the substrate, and the recording layer is irradiated with track recording light having an energy density necessary for blackening. By doing so, a blackened stripe-like recording track is formed in the area irradiated with the track recording light, and by irradiating the information pit recording light having a higher energy density than the track recording light onto the recording track, the information pit recording light is formed. An optical recording medium characterized in that information pits can be recorded by melting and evaporating the irradiated portion. 2. The optical recording medium according to claim 1, wherein the recording layer is formed of Te or Bi-containing carbon disulfide or styrene discharge polymerized film. 3. The optical recording medium according to claim 1, wherein the recording layer is made of chalcogenite glass. 4. The optical recording medium according to any one of claims 1, 2, and 3, characterized in that a reflective layer is interposed between the substrate and the recording layer. optical recording medium. 5. The optical recording medium according to claim 4, characterized in that an optical interference layer is interposed between the recording layer and the reflective layer. 6. On an optical recording medium having a recording layer formed of a film that blackens with heat, scan a pattern of recording tracks to be recorded with track recording light having an energy density necessary for blackening, and record along the pattern. A striped recording track with optical contrast is formed by blackening, and then, while the write/read head is made to follow the recording track, the recording track is covered with an information pit recording light pulse having a higher energy density than the track recording light. An optical recording method characterized by recording information pits by melting and evaporating the upper recording layer.