JPH03157817A - Optical recording device - Google Patents

Abstract

PURPOSE:To form a thinner protective layer or to use no protective layer by dispersing such a phase-transition material which controllers optical properties of the medium in another material having higher melting point, thereby shutting influences from outside. CONSTITUTION:The first material 19 shows reversible or irreversible changes among plural states which are detectable, according to the irradiation conditions of laser light, and is dispersed in the form of fine particles into the second material 18 which is transparent and has higher melting point than that of the first material 19 to form the information recording thin film. By embedding the first material 19 which contributes to recording in the material 18 of higher melting point, the first material 19 can be protected from outside atmosphere without using a special protective layer. Thereby, the total thickness of the recording medium can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical recording device that records high-density information on a recording medium using a high-density energy flux such as a laser beam.

BACKGROUND OF THE INVENTION It is well known that optical recording media are capable of recording at a much higher density than conventional magnetic recording media. For example, when comparing magnetic recording media and optical recording media in terms of areal recording density, in the case of magnetic recording, it is necessary to ensure the output;
Alternatively, due to the problem of tracking accuracy limits, the track pitch must be an order of magnitude larger than the recording mark pitch, whereas in optical recording, grooves for light guides are formed on the substrate in advance, etc. When compared in terms of capacity as a recording device, the track pitch can be reduced to the order of the wavelength of light using this method, and by doing so, it is possible to easily achieve high densities from several times to IO times that of magnetic recording media.
There is no such large difference as seen in the areal recording density.In the case of optical recording devices, only one recording surface can be accessed at the same time, but in the case of magnetic recording devices, the recording medium can be This is because by using a stacked structure in which many sheets are stacked and a small magnetic head called a flying head, many surfaces can be accessed at the same time, increasing the capacity of the device.

It is said that the means to dramatically increase the recording density of the optical recording medium itself is to change the recording mechanism from conventional heat mode recording to photon mode recording.
Although wavelength multiplexing power distribution using PHB (photochemical hole burning) and multilayer film recording using photochromic materials have been proposed, the former requires use at extremely low temperatures, and the latter requires wavelength tunable lasers or wavelength The inventors believe that the development of semiconductor lasers is considered difficult because multiple lasers with different sensitivities are required, and the sensitivity is in the ultraviolet region. In view of this situation, we have already filed an application for a large-capacity optical recording device (Japanese Patent Application No. 1-9774).
No. 1). This (Yo) adopted a single-plate structure for the optical disk, adopted a structure in which the recording light is incident from the recording film side on both surfaces, and used a floating optical recording head. It enables the use of an objective lens (referred to as N, N) and enables higher density recording than conventional methods. This makes it possible to dramatically increase the capacity of the device.Furthermore, by enclosing it in an airtight box, it eliminates the influence of dirt and dust, and even if the protective layer of the recording medium is made thin, it is possible to dramatically increase the capacity of the device. It has already been disclosed that the recording medium can be made less susceptible to the influence.Furthermore, it has been disclosed that phase change materials are effective as recording media because they can be overwritten by a single laser beam. A characteristic of high-density optical recording devices that use a single-disk structure disk and a floating optical recording head is that the distance between the recording medium and the optical recording head is short, at most a few hundred micrometers. N, A. This has the advantage of being able to use an objective lens, but since the working distance of the 1-nons is shorter in the case of -j, a thicker protective plate can be used to protect the recording film as in the past. In other words, in the conventional example, the mechanical strength of the recording film was insufficient in the event of a collision between the optical recording head and the medium, and the role of separating the recording thin film from the outside air was Moisture resistance 1 due to the lack of a protective plate
In order to solve this problem, the conventional example discloses providing a layer of material on the surface of the recording film, which is harder than the material that constitutes the recording film, with a thickness of several tens of micrometers or more. In order to create a thick protective layer, methods such as vacuum evaporation and sputtering are impractical due to cost reasons, and methods such as spin cord are used to control the thickness of the film. The purpose of the present invention is to solve the problems in realizing a high-density optical recording device as described above, and to provide an optical recording device with excellent durability and reliability. That is.

Means for Solving the Problems The present invention (Company) In order to solve the above-mentioned problems. 1. A recording medium comprising an information recording thin film on both sides of a single substrate, which is formed by dispersing the material No. 1 as fine particles in a second material that is optically transparent and has a high melting point (compared to the first material above). Use 1. X. A means for rotating or moving the recording medium, and a means for rotating or moving the recording medium, disposed in close proximity to both sides of the recording medium, and rotating or moving the recording medium at a predetermined distance according to the resistance of surrounding environmental gas as the recording medium moves. (7) An optical recording device comprising at least an optical recording head for recording information in accordance with information on each recording thin film of the recording medium; This is an optical recording device using a laminated recording medium.

The present invention also provides an optical recording device in which the above recording medium (layered recording medium) is stored in an airtight box.

By dispersing the phase change material that substantially controls the changes in the optical properties in another substance with a high melting point, it becomes possible to block the influence of the outside air, making it possible to make the protective layer thinner, and furthermore, to make the protective layer thinner. This makes it possible to configure unnecessary recording media. By making the protective layer thinner or making it unnecessary, the optical smoothness of the recording layer can be improved and signal quality can be improved. To the same number The distance between the optical recording head and the recording medium is increased, reducing the risk of collision.

Furthermore, by making the medium described in H into a single plate, a laminated structure can be constructed with a practical thickness. Overall, an optical recording device with high reliability and excellent recording characteristics can be realized.

Also, by storing it in a sealed box, stable operation is possible without being affected by outside air.

Embodiments 1-F, with reference to the drawings (7) Although one embodiment of the optical recording apparatus of the present invention will not be described, FIG. 1 is a block diagram of the optical recording apparatus of the present invention.

The recording medium section 4 is fixed to a motor 5 via a rotating shaft 6, and is driven to rotate at high speed, for example, at a rotation speed of about 1800-540 rpm. A small optical recording head 10 consisting of a slider 7, an objective lens 8, and a mirror 9 or a deflection prism 9 is disposed on one side of the recording medium section.
The mechanism is such that it floats to a certain height as the medium section rotates.

The mirror or deflection prism section is supplied with a laser beam 11 emitted from a noser (not shown) installed further outside the outer periphery of the medium section, and focused by an objective lens onto the recording layer 2 for recording and reproduction. Perform rewriting, etc. Since the flying height is determined to be a constant height, the laser beam can be focused onto the recording medium section.

The first point of the present invention lies in the structure of the recording medium section and the selection of the type of recording layer. The recording medium section 4 has a structure in which a recording layer 2 is provided on both surfaces of the substrate 1 (and a protective layer 3 is formed as needed (17), which is not necessarily required in the present invention). The basic configuration of the recording layer is shown.

Although the recording layer 2 has a structure that can be called a so-called matrix structure, in other words, in the present invention, the recording thin film and 17
The first substance 19 that changes reversibly or irreversibly between a plurality of detectable states 9-0- according to changes in the irradiation conditions of the norther beam is optically transparent and the first substance described above. An information recording thin film formed by dispersing fine particles in a second substance 18 having a higher melting point than that of the second substance 18 is applied.

By sealing the first substance 19, which substantially contributes to information recording, in the second substance 18 with a high melting point, the first substance 19 can be shielded from the outside air without using a special protective layer. However, the thickness of the recording layer 2 itself is approximately 500 nanometers at most, and the thickness including the conventional protective layer (several hundred micrometers) ), it is possible to make it three orders of magnitude thinner than the previous patent application (Japanese Patent Application No. 1-97741), and of course, to further improve moisture resistance, a protective layer and a wear-resistant layer are added as disclosed in the previous patent application (Japanese Patent Application No. 1-97741). However, even in this case, the thickness of the entire recording layer is several tens of micrometers, which is about an order of magnitude thinner than the conventional one, and a sufficient effect can be expected.

It is important for the substrate 1 to have an optically smooth surface and to have as little warp, distortion, etc. as possible. .

Further, the surface roughness is desirably 50 nanometers or less, and for a more stable drive, 10 nanometers or less. As the material, metal plates such as glass plates, copper plates, and aluminum plates, resin plates such as PMMA plates, polycarbonate plates, and vinyl chloride plates can be used. However, since the basic principle of the present invention is to use a single plate, it is preferable to use a glass plate or a metal plate because of the need for strength and rigidity.There is no need to stick to a thickness of 1.2 mm, as is the case with conventional optical discs. By making it thinner, you can reduce the overall size, and by making it a little thicker, you can ensure stable rotation. Metal plate If it is a resin plate, it is 0.
．． From 3mm to 5m If it's a glass plate, about 0.5mm to 5mm is appropriate. Spiral concentric source signal pit rows are provided in advance on the substrate surface for the purpose of tracking the recording and reproducing light during recording and reproducing. As for the tracking method, the method used in conventional optical disk drives can be applied. Although a resin plate glass plate is superior to a metal plate in that it can be directly formed on a metal plate, grooves can be formed using the 2P method in the case of a metal plate, but a single-sided double-sided structure is achieved by laminating two sheets together. This is because the overall thickness can be made thinner than when using a multilayer recording medium, and as will be described later, when using a stacked recording medium, this is an especially important component from the perspective of practical use of compact 4K devices. In the figure, the first material 18 that forms the recording layer 2 can record without changing its shape. Unlike magneto-optical recording, it does not require a bias magnetic field and can record and reproduce using only light, so both sides can be used simultaneously. 4. Phase change materials are particularly effective from several points of view, such as the fact that even when dispersed in other substances, the same effects as in the case of a continuum can be expected. A thin film that undergoes a phase change depending on the laser beam irradiation conditions, for example, between an amorphous phase and a crystalline phase, between an amorphous phase and a metastable crystalline phase, or between a crystalline phase and another crystalline phase, such as Ge-Te, Ge-Te. -3n, Ge-Te-
8b, Ge5b-Te-Pd, Ge-Te-B1.
Ge-Te-3b-3e, Bi-3b-Te-3
e, Ge-Te-3n-Au, Ge-8e-Te,
5b-3e, 5b-3e-Te, In-Te,
5b-Te, In-8e, 5b-8e, In-8
e-Tl, In-3e-Tl-Co, Ga-Te-
8e, Te-0-Ge-8n, Te-0-Ge-3n
- Selenium-based thin [I Ga-8b, In-8b, Au-3
b.

Ge-8b, Cu-3b, B1-3b, Zn-3
Thin films based on antimony, such as Ag-3b and Ag-3b, and thin films that utilize the difference in reflectance due to changes in metal-to-metal band structure, such as Ag-Zn, are used. Toriwa method
Overwriting possible with a single laser beam includes GeTe, Ge5bTe, In5bTe, In5
eTICc4 5bSa, GaSb 8 Chestnut Among them, Ge5bTe system is effective. The second substance 18 for dispersing the phase change substance has a melting point higher than that of the first substance 19, has a high boiling point, and is optically transparent to the wavelength of the light source used. Select a system with high hardness Considering that the melting point of the first substance 19 is at most 800°C, the melting point of the second substance should be set higher than that, and the one below 13-14- Can be used. -4, that is, 5i02. T
iO2°A 1203. ZrO2, GeO2, Ta2
Oxidation of 05 etc. Nitridation of AIN, SiN, BN etc. 1
Chalcogenization of ZnS, Zn5e, carbonization of SiC, DLC (diamond-like carbon)
Moon tJ, cBN (4-ubiquitous boron nitride) films and mixtures thereof can be used. When a protective layer is employed, the second material 18 can be used as is.

The second point of the present invention is to float on each surface of the recording medium 4.
The point is to place a type of optical recording head 10. The optical recording head IO is composed of a slider 7, an objective lens 8, and a mirror 9, and as the recording medium 4 rotates at high speed, an air layer of several micrometers to several tens of micrometers is formed on the surface of the recording medium. It will float to the surface. A laser beam 11 emitted from a laser light source such as a semiconductor laser passes through a collimator lens, becomes a parallel beam, reaches an objective lens via a mirror or prism 9, and is focused onto a recording surface, where recording is performed. In this case, the distance from the objective lens 8 mounted on the slider 7 to narrow down the laser beam 5-11 to the surface of the recording medium can be reduced to a minimum of several microns, so the aperture of the aperture lens can be made as small as possible. can,
For the same reason, the conventional 0. It becomes possible to use the objective lens 8 with a large N, A of about 5 to about 0.6 to 0.9, and it is possible to improve the recording density.

The material of the slider 7 can be made of the same material as the lens, such as those used in flying heads for magnetic recording, such as a zinc-based alloy, as it must have a certain degree of hardness and be light. In other words, by forming the objective lens 8 and the slider 7 as one unit, it is possible to solve the problem of how to ensure precision in attaching the lens to the slider 7. As for the material, glass or plastic can be used (if a material that is relatively easily abraded such as plastic is used, a wear-resistant layer 16 such as the above-mentioned DLC film is applied to the surface of the slider 7 as shown in FIG. 4). can be formed.

6- The flying height of the optical recording head (the distance between the medium surface and the head) is determined by the relative speed between the head and the medium. Therefore, when a certain rotational speed (in terms of linear velocity) is given, the distance between the lens and the medium is uniquely determined, and it becomes possible to perform the necessary force-shinging (recording, erasing, and reproducing). .As a means of keeping the linear velocity constant, the so-called C
The LV method is an effective method. Although FIG. 1 omits the tracking plate, recording medium transport mechanism, etc. that are naturally necessary for an optical recording device, it goes without saying that these mechanisms are necessary. The point is that the system in which the recording medium section 4 and the optical recording head 10 are stacked can be constructed compactly, and the capacity of the apparatus can thereby be dramatically increased. FIG. 3 shows a schematic diagram of a recording apparatus according to the present invention constructed using a laminated structure. The mouth portion 14 is an example of a recording body having a stacked structure composed of four recording media. The thickness of one recording medium is 0.5 to 2 mm (1-) l/, and the spacing between each medium can be selected to be about 3 to 5 mm, so the height is so-called half-hide (42 mm). Approximately 4 to 10 sheets of full hide (
84 mm), it is possible to have a stacked recording medium having about 8 to 20 recording media, and the capacity of the device increases at once by more than 10 times. The optical recording head 1 is provided independently on each side of the recording layer.
By arranging 0, each surface can be accessed simultaneously.

The recording medium can be used by storing the entire body in an airtight box 13 to isolate it from the effects of dust, dust, wind, humidity, etc. The airtight box 13 is completely isolated from the outside air. It is possible to fill the storage with a rare gas such as argon, or to circulate clean air through a filter.Especially in the case of the former structure, the humidity of the recording medium is low and there is little concern about oxidation, so it is protected. This creates a synergistic effect, such as the ability to thin or remove layers, increasing flexibility in media design.

FIG. 5 shows the structure of a recording medium used in the recording apparatus of the present invention. In each figure, parts with the same pattern indicate equal components. Mouth part AI has the simplest structure in which recording layers 2 are provided on both sides of a substrate 1. The recording layer includes a phase change material, i.e. a first material, in a continuum of second material 18.
It has a structure in which fine material particles 19 are dispersed.

B1 is a structure in which a material having a higher melting point than the recording layer 2, such as a dielectric layer 15, is provided between the substrate 1 and each recording layer 2.C1
ADI has a structure in which similar layers are provided on both sides of the recording layer 2. ADI has a structure in which a dielectric layer 15 is provided only on the surface of the recording layer 2. When provided above the recording film, it is required to be transparent. El has a structure in which a reflective layer 20 is provided between the recording layer 2 and the substrate 1. H1 shows an example of a structure in which a dielectric layer 15 is formed on the surface of the El structure. The reflective layer 20 functions to increase the light absorption efficiency in the recording layer 2 and to control the diffusion rate of the generated heat, and is made of At, Au, Pd, C.
u, Ti, Ni, Cr, Ge, Si, Fe
, Sb, Bi, Sn, Ta, W, and other metals can be used alone or as an alloy between them.

Fl shows a structure in which a dielectric layer 15 is sandwiched between a reflective layer 20 and a recording layer 2, and G1 shows a structure in which a dielectric layer 15 is further formed on the surface of the recording layer 2 in the structure of Fl. Recording layer 2
By providing the dielectric layer 15 between the recording layer 2 and the reflective layer 20, it becomes possible to change the distance between the recording layer 2 and the reflective layer 20, making it possible to optimize not only the optical properties but also the thermal properties. . A2 to H2 each show an example of a structure in which the protective layer 3 is provided in an Al--Hl structure.

The present invention will be described in detail below with more specific examples.

Example 1 The recording medium section 4 has a stacked structure of five layers.The substrates 1 are glass plates each having a diameter of 130 mm and a thickness of 1 mm, and have one tracking groove on both sides with a depth of 72 nm and a width of 0.6 micrometers. It is formed in a spiral shape with a pitch of .5 microns.

The direction of rotation of the spiral is opposite on the top and bottom surfaces of the plate.9 This makes it easy to access the top and bottom surfaces of each medium in parallel. Each recording layer 2 has the second
5b as the first substance 19 in a mixture of zinc oxide of the substance 18 and silicon diacid 9-
In a system in which 2Tes fine particles are dispersed, the volume ratio of each other is 50% =
To achieve 50% binding, a 5b2Tes plate is formed on a target made of the second material 18 to a thickness of about 1100 nm by sputtering in a peirgon gas atmosphere.
The recording thin film is formed in an amorphous state. 9. Each recording medium section 4 is screwed to the rotating shaft of a motor at a spacing of 4 mm to form a laminated recording medium section with 5 #10 surfaces. 9. On each recording surface, the slider 7 and N, 0. A laser diode with a wavelength of 780 nanometers is used as the light source.The overall thickness of the recording device is 25 mm, making it a compact recording device. The number of heads was at least 10 times larger. When the motor connected to the recording medium section was rotated at a speed of 1800 rpm (at a recording diameter of 100 mm), each head had a height of about 20 micrometers. When the recording surface is irradiated continuously with a laser power of 10 mW, the irradiated area crystallizes and a track with high reflectance is formed.92 ) When a laser was modulated between 20 mW and 10 mW at a frequency of 5 MHz and irradiated onto the track with high reflectance, the area irradiated with high power became amorphous, the reflectance decreased, and recording was performed. When the recording section was reproduced with the power set to ImW, a reproduced signal of 50 dB was obtained.93) When the laser was modulated at a frequency of 2 MHz between 20 mW and 10 mW and irradiated on the track with the high reflectance, the result was still high. The part irradiated with high power becomes amorphous and the reflectance decreases, and the part irradiated with low power becomes crystallized and the reflectance increases, and the information is rewritten.9 When the rewritten part was played back with the irradiation power set to ImW, it was 5MHz. component is reduced by 30dB1. ,
It was confirmed that recording of 50 dB was performed for the 2 MHz component.21 22- Example 2 The recording device shown in Example 1 was stored in an airtight box (
7 Prepare a device and fill the airtight box with nitrogen gas 1. In addition, this device was kept in an environment of 80 degrees Celsius and 80% relative humidity, and a rewriting test was conducted for 100 hours, while the device of Example 1 was used for 2000 hours.
While a slight decrease in the CN ratio was observed in the rewrite operation after 5000 hours, it was confirmed that the device of Example 2 performs the same self-replacement rewriting operation even after 5000 hours, and compared with the present invention. 5b2 as the recording layer of the recording medium to
Equipment with a uniform layer of Tea (airtight box 2)
When we conducted a similar experiment, we found that the characteristics had already deteriorated after approximately 500 samples. By using a recording head that constitutes a recording head, a recording layer that constitutes a variety of single-plate double-sided recording media, and a recording thin film with a seven-trix structure, multiple states that can be detected according to changes in the irradiation conditions of the buried laser beam can be created. A first substance that changes reversibly or non-reversibly between the two is dispersed as fine particles in a second substance that is optically transparent and has a higher melting point than the first substance. It has been shown that by adopting an information recording thin film, compared to conventional optical disk devices, it is possible to achieve a capacity that is more than an order of magnitude larger with the same device size, and to obtain high reliability. The recording device overcomes some of the problems that current optical recording devices face as they become more compact.In other words, in the past, it was assumed that the optical recording head and the recording medium would collide. (7) The problem of reduced moisture resistance due to the lack of a durable intervening plate due to the lack of mechanical strength of the recording film and the lack of a protective plate that separates the recording thin film from the outside air, etc. This can be solved by creating a matrix structure by mixing phase-changing optical recording materials with a protective component (-The present invention makes it possible to realize a highly reliable, large-capacity optical recording device. one%

[Brief explanation of the drawing]

FIG. 1 shows the basic structure of one embodiment of the optical recording device of the present invention. FIG. 2 shows the structure of a recording layer applied to the optical recording device of the present invention. Fig. 4 shows an embodiment of the structure in which the slider of the optical recording head part of the present invention and the objective lens are integrated. Fig. 5 shows the optical recording medium of the present invention. FIG. l...One substrate, 2...Recording layer 3...Protective clothing 4
...Disperses the recording medium 5...Motor 6...Rotation $+h, 7...Slider, 8...Objective lens, 9...Mirror (deflection prism), 10...
Optical recording spatula 1 ll...laser light 12...
・Groove, 13... Airtight pocket 14... Stack structure record (& 15... Dielectric layer 16... Wear-resistant layer,
17... Media description 18... Second substance, 19.
...First substance (phase change material), 2o...Reflection monitor

Claims (8)

[Claims] (1) A first state that changes reversibly or irreversibly between a plurality of detectable states according to changes in laser beam irradiation conditions.
A recording medium comprising, on both sides of a single substrate, an information recording thin film formed by dispersing a substance as fine particles in a second substance that is optically transparent and has a higher melting point than the first substance; a means for rotating or moving the recording medium; and means disposed close to both sides of the recording medium, while maintaining a predetermined distance by resistance of surrounding environmental gas as the recording medium rotates or moves. An optical recording device comprising: an optical recording head that flies and records information on each recording thin film of the recording medium according to information. (2) The first state changes reversibly or irreversibly between a plurality of detectable states in response to changes in laser beam irradiation conditions.
A plurality of recording media each having an information recording thin film on both sides of a single substrate formed by dispersing a substance as fine particles in a second substance that is optically transparent and has a higher melting point than the first substance. A stacked recording medium, a means for rotating or moving the stacked recording medium, and a means for rotating or moving the stacked recording medium, each disposed close to both sides of the recording medium, and a means for rotating or moving the stacked recording medium, and a means for rotating or moving the stacked recording medium; An optical recording device comprising: an optical recording head that flies while maintaining a predetermined distance by a resistor and records information on each recording thin film of the recording medium according to information. (3) A recording medium, a means for rotating or moving the recording medium, and an optical recording head are provided in an airtight box for isolating them from changes in the external environment. The optical recording device according to claim 1 or 2. (4) The optical recording device according to claim 1 or 2, further comprising an objective lens having a numerical aperture of 0.6 or more. (5) The optical recording device according to claim 1 or 2, wherein the recording medium is moved or rotated at a constant linear velocity. (6) Using a substance that causes a reversible phase change phenomenon between an equilibrium phase and a nonequilibrium phase, or between a nonequilibrium phase and another nonequilibrium phase depending on the laser beam irradiation conditions as the first substance, optical 3. The optical recording apparatus according to claim 1, wherein rewritable recording is performed by detecting changes in optical characteristics as signals. (7) The optical recording apparatus according to claim 1 or 2, wherein each recording surface is overwritten by simply changing the irradiation intensity of a single laser beam. (8) Each recording surface has a spiral continuous groove or a spiral pit row for guiding light as a recording and reproducing means, and the winding direction is opposite on the top and bottom surfaces of the medium. The optical recording device according to claim 1 or 2, characterized in that the optical recording device has a direction.