JP3455433B2 - Optical recording medium, apparatus and reading method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording device and its medium.

[0002]

2. Description of the Related Art A conventional optical recording medium has a substrate such as a magneto-optical disk (MO) coated with a magnetic material, or an uneven structure on a metal thin film surface on a substrate such as an optical disk (CD). Data was recorded by holding it, and by the continuity and discontinuity of its magnetization and unevenness. Also, in the optical recording device, the surface of the recording medium is irradiated with laser light,
Recording and reading are performed by discriminating the magnetic state or the unevenness of the surface by reflected light.

In a data-writable recording device and medium, this is done by changing the direction of magnetization of the magnetic material applied to the surface of the medium substrate. But,
In such a device, basically only one bit can be read at the time of reading, and in order to make the surface condition of the recording medium correspond to the recording condition, the recording density should be sufficiently increased by the diffraction limit. I can't. Therefore, since it is not possible to read multiple bits at the same time to perform high-speed data processing, when performing processing by reading a large amount of data from a large-capacity recording device, the operation speed at the time of reading from the medium is a rate-determining step. It was

Recently, as a method of improving the recording density per unit area, a DV using a CD bonding technique is used.
D etc. have been put to practical use. However, since this technology uses the bonding of disks with the same characteristics, it is not possible to read the information recorded on each disk at the same time, and the reading speed is different from the conventional technology compared to the improvement in recording density. Absent.

[0005]

As described above, it is difficult to dramatically increase the capacity of conventional optical recording media and devices. In addition, since data is read serially bit by bit, it is difficult to dramatically improve the reading speed.

Particularly, as the amount of data to be handled increases, the processing speed becomes a problem. Therefore, in order to put a large-capacity recording device into practical use, it is necessary to improve the recording density and the data processing speed at the same time. .

[0007]

In order to solve the above problems, in the present invention, thin film organic molecules having semiconductor fine particles embedded therein are stacked, or finely arranged fine particles are used. The present invention includes a substrate, a layer of a first composite cell formed on the substrate, and a layer of a second composite cell formed on the layer of the first composite cell and different from the first composite cell. The first composite cell and the second composite cell are optical recording media including semiconductor fine particles and insulating organic molecules.

Further, a first light source, a first control device for controlling the irradiation point of the first light source, a second light source for irradiating from a different direction from the first light source, and an irradiation point of the second light source are provided. A second control device for controlling, a third light source that is incident on the surface of the recording medium in a direction perpendicular to the recording medium, and a spectroscopic device that receives irradiation light from the third light source through the recording medium, the first light source And the frequency of the emitted light of the second light source resonates with the two-photon allowable level of the semiconductor fine particles contained in the recording medium.

Further, a substrate, a layer of a first composite cell formed on the substrate, and a layer of a second composite cell formed on the layer of the first composite cell and different from the first composite cell. The first composite cell and the second composite cell each include a light source for irradiating light perpendicularly to the surface of an optical recording medium containing semiconductor particles and insulating organic molecules, and a recording medium for irradiating light from the light source. And a spectroscopic device for receiving the optical states of the first composite cell and the second composite cell obtained from the spectroscopic device.

In addition, the substrate, the layer of the first composite cell formed on the substrate, and the layer of the second composite cell formed on the layer of the first composite cell and different from the first composite cell. The first composite cell and the second composite cell are different from the first light source for irradiating the surface of the optical recording medium containing semiconductor fine particles and insulating organic molecules with energetic light, and the first light source. A second light source that irradiates the optical recording medium surface light from an azimuth direction, and emits light having a frequency whose sum with the frequency of the first light source emitted light resonates with the two-photon allowable level of the semiconductor fine particles; In the optical recording / writing method, the semiconductor fine particles at the point where the emitted light of the first light source and the emitted light of the second light source are simultaneously irradiated are excited by two photons.

A substrate, a layer of the first composite cell formed on the substrate, and a layer of a second composite cell formed on the layer of the first composite cell and different from the first composite cell. An optical recording medium, characterized in that the first composite cell and the second composite cell contain semiconductor particles and insulating organic molecules, and a first light source and an irradiation point of the first light source. A first control device for controlling, a second light source for irradiating from a direction different from that of the first light source, a second control device for controlling an irradiation point of the second light source, and an incidence from a direction perpendicular to a recording medium surface. And a spectroscopic device that receives the irradiation light from the third light source through the recording medium, and the sum of the frequencies of the emitted light of the first light source and the emitted light of the second light source is the recording medium. It is characterized by resonating with the two-photon allowable level of semiconductor particles contained in That is an optical recording system comprising a optical recording device.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a layer in which layers made of organic molecules containing semiconductor fine particles are laminated, or fine particles in which organic molecules containing semiconductor fine particles are wrapped in a polystyrene film are regularly arranged Is provided on the medium substrate. Hereinafter, a minute region of a layer in which semiconductor particles are embedded in an organic molecule, or a unit of particles is referred to as a composite cell.

In the composite cell, when the semiconductor fine particles are excited by two photons, energy transfer from the semiconductor fine particles to the organic molecules occurs. The result is a permanent change in the structure and electronic state of the organic molecule. This change appears as a change in the optical response of the organic molecule. That is, the presence or absence of two-photon excitation of the semiconductor fine particles and the presence or absence of change in optical response of the organic molecule are associated with each other. Therefore, it is possible to perform writing by exciting the semiconductor fine particles with two photons, and to read as a change in the optical response of the organic molecule.

The fine semiconductor particles have an average of about 1-10 nm and a dispersion of 0.
A material having a diameter of about 3-0.5 nm can be used.
By using the semiconductor fine particles of this level, a large optical response coefficient can be obtained and an excited state can be efficiently generated.

In the present invention, a composite medium in which composite cells are regularly arranged in three dimensions is used as a recording medium. Data writing to this medium is carried out by entering two monochromatic or nearly monochromatic laser beams that resonate with the two-photon excitation energy of the semiconductor particles from two different directions. The incident laser light is selected such that the sum of the frequencies of the two laser lights resonates with the two-photon allowable level of the semiconductor fine particles.
These wavelengths may be different from each other,
In either case, it is possible to select one having a wavelength different from the absorption bands of semiconductor fine particles and organic molecules.

Two-photon excitation occurs in the semiconductor fine particles in the composite cell to which two laser beams are simultaneously incident, and the optical response of the organic molecule is changed. At this time, it is necessary for the semiconductor particles to be supplied with energy of sufficient intensity necessary for the two-photon excitation to occur in the composite cell in which the two-photon excitation occurs.

Since two laser beams are made to enter from different directions, it is possible to adjust so that both incident lights are irradiated to only one desired composite cell, so that the three-dimensionally laminated composite cells can be adjusted. It is possible to two-photon excite only the semiconductor fine particles in one desired composite cell in the cell. Therefore, it becomes possible to write to one of the three-dimensionally stacked composite cells.

The reading of data is performed by irradiating the medium substrate with laser light having a wavelength range including the absorption band of organic molecules, and converting the amount of change in absorption obtained by the spectroscope into an electric signal.

Further, the recorded contents can be erased by irradiating the medium with a laser beam or by heating the medium to return the organic molecules to the state before the optical change caused by the excitation movement. .

Further, in order to improve the reading speed of the recording medium obtained by the above structure, the following method can be adopted. A plurality of types of composite cells having different types, compositions, and molecular weights of organic molecules are arranged in a stack in the incident direction of one read light. However, as the semiconductor fine particles, the same substance and the same size are used for all the composite cells.

The light absorption characteristics of the composite cell differ depending on the type, composition, molecular weight and the like. Therefore, when a read light having a sufficiently wide spectrum width is used and the transmitted light output of the medium is analyzed by a spectroscope, a series of data stacked in the incident direction of the read light can be read at one time. In other words, the composition of the medium of the present invention comprises a first organic molecule layer, a first organic molecule layer,
Is a three-dimensionally laminated composite cell, which is a layer of organic molecules.

(Embodiment 1) The first embodiment according to the present invention will be described in detail below. In Example 1, fine particles composed of organic molecules having semiconductor fine particles embedded therein are used as a composite cell, which is regularly arranged.

First, as shown in FIG. 1, polystyrene spheres 3 are provided with organic molecules 4, for example, polydiacetylene, and semiconductor fine particles 2 having an average diameter of about 3 nm and a dispersion of about 0.3 nm, such as cadmium (CdS). The fine particles are encapsulated to form the composite cell 1.

FIG. 2 shows the apparatus configuration of this embodiment. In the recording medium, a first composite cell layer 311 of 4-butoxycarbonylmethyl-urethane (4BCMU) polydiacetylene containing semiconductor fine particles is formed on the substrate 10, and thereon.
A second composite cell layer 321 of polytoluene sulfonate diacetylene (PTS diacetylene) containing semiconductor particles is formed. Here, the diameter of the composite cell is about 500n
It is about m. In the colloidal solution, the surfaces of the polystyrene spheres 3 can be aligned by charging and the colloidal solution can be applied to the medium substrate to form a three-dimensionally laminated composite cell layer.

A recording / writing device for this recording medium comprises a first laser light source 32 which emits light of a wavelength of about 440 nm, a second laser light source 33 which emits light of a wavelength of about 480 nm,
It has a readout light source 34 with a spectral width from about 580 nm to about 630 nm. The first laser light source 32, the second laser light source 33, and the readout light source 34 are respectively control devices 35, 36,
The 37 allows precise positioning of the light irradiation position. Further, the reading light source 34 is sandwiched across the recording medium.
A spectroscopic device 38 that disperses the components that pass through the first and second composite cell layers 321 and 322 is provided on the opposite side.

By irradiating both the laser light from the first laser light source 32 and the laser light from the second laser light source 33 positioned by the control devices 35 and 36, one specific one or a plurality of adjacent ones in the composite cell layer 31 are irradiated. Two composite cells are two-photon excited. Energy transfer from the excited semiconductor fine particles to the organic molecules occurs, and the optical characteristics of the organic molecules change.

FIG. 3 is a diagram showing absorption spectra of organic molecules in polystyrene spheres of the first composite cell and the second composite cell. The wavelength on the upper side of the horizontal axis corresponds to the first composite cell, and the wavelength on the lower side corresponds to the second composite cell. It can be seen that the organic molecule absorption spectrum A before recording has a peak at about 590 nm, but the peak in the organic molecule absorption spectrum B after recording after irradiation with laser light shifts to about 690 nm. Also in the second composite cell, there is an absorption peak at about 620 nm before recording, but it shifts to about 720 nm after recording.

The above is the writing process. When performing reading, the reading light from the reading light source 34 positioned by the control device 35 is applied to the recording medium, and the light transmitted through the recording medium is received by the spectroscopic device 38 positioned by the control device 37. To do.

Of the readout light transmitted through the composite cell layer 31, the intensities of the light with wavelengths of about 620 nm and about 590 nm are examined and taken out as an electric signal by the photomultiplier tube 39. When the transmitted light intensity is 50% or more compared to the state without recording for each wavelength, it is associated with “1”, and when it is less than that, it is associated with “0”, so that the information recorded on the two layers is converted into a digital signal. Can be read simultaneously.

This is the reading process. here,
Although the transmitted light is used for reading, if the substrate 10 that reflects the reading light is used, the reading can be performed by using the reflected light.

(Second Embodiment) A second embodiment will be described below. FIG. 4 shows a recording medium 51 in which the composite cell layers described in the first embodiment are three-dimensionally arranged and processed into a disk shape, and an apparatus having a mechanism for rotating about the central axis.

The same parts as those in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted. The device of this example has a common control mechanism 55 for positioning in the radial direction of the disk, and includes a first laser light source 32, a second laser light source 33, and a reading light source 3.
4 is placed. The first laser light source 32 and the reading light source 34 always enter the recording medium 51 perpendicularly.

Further, the second laser light source 53 also has an angle adjusting mechanism 56 for changing the irradiation position by changing the tilt angle. The spectroscope 38 detects the component of the irradiation light from the reading light source 34 that has passed through the recording medium 51 at the time of reading. The spectroscopic device 57 is positioned by the control device 37 and is controlled in conjunction with the reading light source 34.

Writing is performed by light from the first laser light source 32 and the second laser light source 33. The semiconductor fine particles in the particles irradiated with the light from the first laser light source 32 and the second laser light source 33 are excited by two photons. Energy transfer from the semiconductor fine particles to the organic molecule occurs, causing a change in the optical characteristics of the organic molecule, and data can be recorded by the change. That is, the first laser light source 32
In the composite cell irradiated with both the light from the second laser light source 33 and the second laser light source 33, the absorption characteristics of the organic molecules change as shown in FIG.

In this embodiment, since the fine particles form a layered structure on the disk, the recording position, that is, the composite cell to be written is specified by the rotation of the disk 51 and the positioning in the radial direction by the controller 55, and the second position. This is performed by changing the irradiation angle of the laser light source 33. The angle adjustment mechanism 56 adjusts the irradiation angle of the second laser light source 33.

On the other hand, the reading is carried out by positioning the controller 55 in the radial direction and by rotating the disk 51 in the disk circumferential direction, and irradiating the disk with incident light from the reading light source 34. A spectroscope 38 and a photomultiplier tube 39 are provided on the side opposite to the reading light source 34 with the disk sandwiched therebetween. With these, the read light that passes through the disk is dispersed, and the output light intensity at wavelengths of 620 nm and 590 nm is "0",
It is converted into an electric signal by associating with "1".

In the first and second embodiments, it is also possible to arrange a photodetection device by CCD on the opposite side of the reading light irradiation device to the recording medium for reading. At this time, the CCD should be given wavelength selectivity in sensitivity by using filters that selectively transmit light of about 620 nm and about 590 nm, respectively.

(Embodiment 3) A third embodiment will be described below. In this embodiment, as shown in FIG. 5, in the first embodiment, the substrate 6 on which the CCD photodetector is arranged is arranged.
The composite cell layer 31 is formed on the second layer 2.

The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. The composite cell layer 31 is composed of organic molecules containing semiconductor particles, and the semiconductor particles cause two-photon excitation in a region irradiated with light from two laser light sources at the same time. Energy transfer occurs from the excited semiconductor particles, causing an optical change in the surrounding organic molecules. At this time, the optical characteristics change as shown in FIG. In this way, writing is performed as in the first embodiment.

Under the composite cell layer 31, a CCD having pixels is provided so as to correspond to the size of the area irradiated with the light from the two laser light sources. At this time, CCD
It is advisable to provide wavelength selectivity to the sensitivity by using a filter that selectively transmits light of about 620 nm and about 590 nm, respectively. That is, the recording medium is composed of two layers of polystyrene spheres 31 and a CCD of two pixels that selectively senses two kinds of light.
The recording units consisting of are arranged in a two-dimensional regular array.

When reading data, the reading light source 67 irradiates the entire medium with reading light in the vertical direction when reading data. At this time, since the output of each CCD pixel corresponds to the data recorded content on the polystyrene sphere, the recorded content can be read at one time.

Further, similarly to the first embodiment, it is possible to move the reading light source on the recording medium and read the transmitted light by the substrate 62 on which the CCD is arranged. The composite cell does not have to be composed of particles and may have a layered structure.

In this case, a layer of organic molecules containing semiconductor fine particles of about 500 nm is formed on the substrate to form a recording medium. Here, the size of the composite cell depends on the width of the laser beam used for excitation. That is, the area where the laser beams incident from two directions intersect functions as a composite cell. In other respects, it is the same as the case of using particles.

The present invention is not limited to the above-mentioned embodiments, and as semiconductor fine particles, for example, CuCl (copper chloride (I)), CdSe (instead of CdS (cadmium sulfide),
It is also possible to use cadmium selenide), Si, Ge, InAs (indium arsenide), or the like.

The organic molecules include polydiacetylenes having different side chains other than the polydiacetylenes listed in the above examples, polyacetylenes, photochromic organic molecules, and charge transfer complexes that cause photoinduced phase transition (TTF-CA, etc.).
It is also possible to use.

Further, although the embodiment has described the recording medium having a two-layer laminated structure, a multilayer structure can be formed by using organic molecules having different optical characteristics for each layer.

[0047]

As described above in detail, since the recording medium having a plurality of layers of composite cells is used, the recording density per unit area is increased. In addition, since the optical change of the composite cell of a plurality of layers can be read at the same time, the reading speed is improved. That is, it is possible to obtain an optical recording device having a high recording density and a dramatically improved data transfer rate.

[Brief description of drawings]

FIG. 1 is a diagram of a recording medium using semiconductor fine particles and organic molecules encapsulated in a polystyrene film.

FIG. 2 is a diagram showing the configuration of a recording apparatus according to the first embodiment.

[Figure 3] PTS diacetylene and 4BCM before and after recording
The figure showing the change of the absorption spectrum of U poly diacetylene.

FIG. 4 is a diagram showing a configuration of a recording apparatus according to a second embodiment.

FIG. 5 is a diagram showing a configuration of a recording device according to a third embodiment.

[Explanation of symbols]

10 substrates 31 Composite cell layer 32 First laser light source 33 Second laser light source 35, 36, 37 Control device 38 Spectrometer 39 Photomultiplier tube

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-8-85259 (JP, A) JP-A-2-215587 (JP, A) JP-A-4-62090 (JP, A) JP-A-8- 217982 (JP, A) JP 61-153839 (JP, A) JP 5-62239 (JP, A) JP 62-28941 (JP, A) JP 4-72347 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G11B 7/00

Claims (3)

(57) [Claims] 1. A substrate, a layer of a first composite cell formed on the substrate, and a layer of a second composite cell formed on the layer of the first composite cell and different from the first composite cell. Equipped with,
An optical recording medium, wherein the first composite cell and the second composite cell contain semiconductor particles and insulating organic molecules. 2. A first light source, a first control device for controlling an irradiation point of the first light source, a second light source for irradiating from a different direction from the first light source, and an irradiation point of the second light source. A second control device for controlling, a third light source that is incident on the surface of the recording medium in a direction perpendicular to the recording medium, and a spectroscopic device that receives irradiation light from the third light source through the recording medium, the first light source And the frequency of the emitted light of the second light source resonates with the two-photon allowable level of the semiconductor particles contained in the recording medium. 3. A substrate, a layer of a first composite cell formed on the substrate, and a layer of a second composite cell formed on the layer of the first composite cell and different from the first composite cell. Equipped with,
The first composite cell and the second composite cell receive a light source that emits light perpendicularly to the surface of the optical recording medium containing semiconductor fine particles and insulating organic molecules, and receives light emitted from the light source through the recording medium. An optical recording and reading method comprising: a spectroscopic device, and reading the optical states of the first composite cell and the second composite cell obtained from the spectroscopic device.