JPS5920474B2 - Heat mode laser beam recording method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat mode laser beam recording method, and more particularly to an improved heat mode laser beam recording method in which a protective layer is provided on the recording layer.

Heat mode laser beam recording (hereinafter abbreviated as HMLBR) focuses an intensity-modulated, scanned or deflected laser beam into a high-power density spot and irradiates the recording member to selectively target a portion of the recording member. It is known as a new recording method that performs recording by melting, evaporating, removing, and deforming, and has many features.

In other words, it is a real-time recording that does not require post-processing such as heat development and fixing, and does not require processing liquids, can form images with extremely high resolution and high contrast, and the recording medium is not exposed to room light and does not require darkroom operation. It has the advantages of being suitable for recording electrical signals such as computer output and transmitted time series signals, and being able to add information later. It is thought that it has ample potential to be applied to micro facsimiles, phototypesetting original plates, etc., and contribute to the miniaturization of devices, the advancement of functions, and the improvement of image quality. .

Normally, the configuration of a recording member used in the above-mentioned HMLBR is as shown in FIG.
A recording layer 2 is formed thereon, which absorbs laser light (3 or 3') and is removed by melting or evaporation.

Furthermore, as shown in FIGS. 2 and 3, there is a system in which an antireflection layer 6 is provided on the side where the laser beam (3 or 3') is incident, in contact with the recording layer 2. It has the effect of significantly reducing the reflection of the laser beam (3 or 3') on the 2 surface, so the sensitivity is significantly improved compared to the system with the configuration shown in Figure 1, making it extremely useful. .

However, since HMLBR essentially involves melting or evaporation of the recording layer, various problems may occur if the recording member configured as shown in FIGS. 1 to 3 is used. There are quite a few.

In other words, the working distance (distance from the lens surface to the focal point) of the lens system required to focus the laser beam into a beam diameter of several microns or less is usually short, several hundred microns or less, so when the laser beam is irradiated, the irradiated area The recording layer forming material scattered from No. 5 adheres to the surface of the lens, thereby significantly preventing subsequent recording.

In addition, since the focal depth of the lens system is usually several microns or less, in order to effectively focus the laser beam on the surface of the recording member, the focusing state must be detected by some means, and the result must be fed back so that it is always constant in real time. It is necessary to maintain the condensed state of the light, but the general method of detecting the reflected light from the recording member is preferred because it is simple and highly accurate. As expected,
During laser beam irradiation, since the recording layer forming material scatters from the irradiated portion of the recording layer, the particles or vapor may cause trouble in accurate detection of the reflected light. Furthermore,
Splashed particles or vapor of the recording layer forming material often adhere to the surface of the recording member, and as a result, this becomes a cause of noise in the recorded information, especially when recording an image. In the background area, image characteristics are significantly degraded.

Furthermore, if a recording member has surface scratches or dust adhesion 3, unlike silver halide recording members, veneer film, etc., the scratches and dust are essentially distinguishable from the recording section. It is not possible.

Furthermore, if dust adheres to the information recording section, that is, the part from which the recording layer forming material has been removed (5 in Figures 1 to 3),
This is extremely inconvenient because the same result occurs in cases where the information is unclear, especially when reading the information.
More specifically, in the recording member for HMLBR,
Since the thickness of the recording layer 2 or (recording layer 2 + antireflection layer 6) 4 is on the order of 1 μm at most, scratches on the recording layer 2 easily reach the surface of the support 1, and this also causes damage during readout. This results in a loss of reliability of the recorded information.

' In particular, Bi, which has high sensitivity as a recording material for HMLBR, has a weak mechanical strength and is easily damaged, so it must be handled with greater care.

To explain the above with reference to FIG. 4, the scratches 7 on the recording layer 2 are essentially the same as the information recording portion 5.

Therefore, the flaw 7 is also read out as part of the information recording section, resulting in confusion of information. Furthermore, when the recorded information is read out as the transmitted light intensity ratio of visible light, the dust 8' adhering to the surface of the recording layer 2 causes the optical density of the recording layer 2 to be
Since it is usually larger than 1.0, the influence is relatively small, but the dust 8 adhering to the information recording section 8 disturbs the recorded information, which is not good. Also, garbage 8,8'
When removing the recording layer 2, there is a risk of newly damaging the surface of the recording layer 2, which is also extremely undesirable. Furthermore, H.M.
For LBR recording members, it is extremely difficult to select a material for forming the recording layer that has sufficient sensitivity and high mechanical strength and is suitable for practical use. This is extremely disadvantageous when trying to provide it at a low price. The present invention has been made in view of the above-mentioned points, and is capable of preventing the recording layer forming material from generating vapor or scattering as particles during laser beam irradiation without degrading the original performance of the recording layer. It is an object of the present invention to provide an HMLBR recording method that does not attach to the surface of a recording member around the irradiation section or to peripheral devices such as an optical system and a measurement system. Furthermore, even if dust adheres to the surface of the recording member, it can be removed without damaging the recording layer, and the surface is extremely difficult to scratch.
An object of the present invention is to provide an HMLBR recording method using an MLBR recording member. The HMLBR recording method according to the present invention uses an inorganic material that is transparent to the laser beam used for recording and has excellent mechanical strength on a recording layer of 0.01 to 10μ made of a nonmetallic material (however, the recording layer is Recording is performed by irradiating a heat mode laser beam recording member with a protective layer of 0.1 to 10μ consisting of a chalcogen compound (excluding the chalcogen compound when the nonmetallic substance is a chalcogen compound) with a laser beam that does not evaporate or deform the protective layer. It is characterized by:

The protective layer of the HMLBR recording member used in the present invention is required to satisfy the following conditions. (1) Be transparent to the laser beam used for recording at least when irradiated (
2) It must be an optically uniform layer (3) It must have high durability, mechanical strength, especially surface strength (4) It must have good adhesion with the recording layer (5) When forming the layer, (6) Avoid deteriorating the recording layer by causing a reaction with the recording layer during information recording. (6) Avoid reducing the original sensitivity of the recording layer. (7) Avoid deteriorating, deforming, or deforming the recording layer during information recording.
Among the above conditions, condition (7) of not being damaged depends on the amount of energy of the laser beam to be irradiated.

That is, as is clear from the examples described below, the protective layer of the HMLBR recording member used in the present invention is transparent to the laser beam used, so the protective layer itself absorbs the laser beam and the temperature rises. Although this can be ignored, the recording layer below the protective layer absorbs the laser beam and is heated to a relatively high temperature, so the heat is transmitted to the protective layer and the protective layer is also heated.

In other words, whether or not the protective layer undergoes thermal deformation or decomposition and destruction depends on the amount of heat transmitted to the protective layer. For example, up to a certain amount of laser beam energy, only the recording layer melts and/or evaporates and deforms, and the protective layer does not change. There may be none, or even if there is, it can be ignored, but if a higher amount of laser light energy is applied, the protective layer will also change. Therefore, for the purpose of the present invention, the laser beam must be irradiated to such an extent that the recording layer forming substance does not evaporate or scatter outside the protective layer by destroying or passing through the protective layer. In the present invention, the protective layer-forming substance used is one that satisfies the conditions (1) to (7) above.Specifically, specific examples of inorganic substances include argon laser, crypto Laser 1, He
- When recording using a visible range laser such as a Ne laser or a near-infrared laser, ZnO, . MgO. ．． Al2
O3, SlO,. SlO2, ZrO2, CeO2, In
Oxides such as 2O3, SnO2, TiO2, or MgF
2, transparent dielectrics and transparent conductors represented by fluorides such as CaF2 and CeF4, Zns. ．． Ges2, Sb2S3
Chalcogen compounds such as are effective.

Although general methods such as coating can be used to form the protective layer using the inorganic substance, the vacuum deposition method using resistance heating and electron beam heating is particularly preferred since it can be formed continuously within a container. It is. According to the method, HML
This method not only prevents dust and the like from adhering to the surface of the recording layer, which is a problem with BR recording members, but is also industrially effective in terms of time and cost required for forming the recording member.

When forming a protective layer with an inorganic material, the film thickness is determined based on the physical property constants of the material, such as refractive index, thermal conductivity, melting point, heat of fusion, etc., and the correspondence between the condition (7) regarding the protective layer and the recording layer material. In relation to this, it can be set individually, but in the present invention, it is generally preferable to have a thickness of 10μ to 0.1μ, and in particular, in the case of a film thickness of 1μ or less, the protective layer is resistant to laser light. It is extremely effective from the viewpoint of improving the sensitivity of the recording member since it exhibits an antireflection effect.

The recording layer forming material of the HMLBR recording member used in the present invention is required to satisfy the following conditions.

1. The absorption coefficient at the wavelength of the laser beam used is large, in other words, the weight (thickness) per unit area is small. 2. The melting point is low enough to cause no practical problems, and the heat of fusion and vaporization are low. , low thermal conductivity; 3. Optically uniform thin film can be easily formed; 4. sufficient mechanical strength and durability. At present, there is no recording layer-forming material that fully satisfies the above requirements. Aluminum, . Zn. ．． Rh. ．． B
There are metal substances such as i, which are formed in the form of a thin film on a support such as glass or an organic polymer film by vacuum deposition or other means.

However, since the metal thin film has a high reflectance, the amount of light energy actually absorbed in the irradiated laser light decreases, and the apparent sensitivity of the metal thin film recording layer decreases.

In addition, its high thermal conductivity causes a decrease in sensitivity due to heat conduction loss around the irradiated area, as well as melting and/or melting of that area.
Alternatively, it causes deformation due to evaporation or the like, thereby reducing recorded information, especially resolution. Furthermore, in order to exhibit effective performance as an HMLBR recording member, the thickness of these metal thin films is usually 1.
Although it is limited to microns or less, the mechanical strength of a thin film of this level cannot be said to be sufficient as a sensitive material, and the mechanical strength of Bi, which is a highly sensitive recording layer forming material, is particularly low, so some practical measures must be taken. There is a need. In view of the above, the recording layer forming materials of the HMLBR recording member used in the present invention include metals, semimetals, semiconductors, rare earth oxides or fluorides,
Furthermore, nonmetallic substances such as so-called chalcogen compounds are preferably used.

Not only are there many types of these nonmetallic substances, but many oxides and chalcogen compounds in particular deviate from the stoichiometric composition, and although it is not possible to specifically list them all, they are relatively high in composition. Examples of sensitive recording layer forming materials include lead oxide, tungsten oxide, titanium oxide, silicon oxide,
Zirconium oxide, magnesium fluoride, calcium fluoride, and the like are useful materials in the present invention. In the present invention, translucency refers to the laser light used, and if the laser light is in a non-visible wavelength range such as ultraviolet light or infrared light, it does not necessarily mean transparency. It doesn't mean anything. A chalcogen compound is an extremely suitable material for forming the recording layer of the HMLBR recording member of the present invention. S
e. A compound containing Te, in a broad sense S, . Se. T
It refers to a group of many types of materials, including e alone.

In particular, since the composition can be continuously changed, an infinite number of types exist. Typical examples include As, . Sb,. P. Ge,. Si,. It contains one or more materials selected from Tl, other metals, and halogen elements. However, when considering pollution, the characogen element is S1, and the materials that should form a compound with it are Ge, In, . Sn. ．． Cu,. Ag
、． Fe,. Bi,. A.I. SilZn. Metals, semimetals, or semiconductors such as Ge. ．． Inlsn,. cu,. It is a chalcogen compound containing one or more types of Agl. When forming a recording layer using the recording layer forming material, it is preferable to form it as a thin film on a support because of the requirement for uniformity.

There are many methods for producing thin films today, each with their own advantages and disadvantages, but the most common are vacuum evaporation and sputtering using methods such as resistance heating, electron beam heating, and ion beam heating. etc. are extremely effective methods in the present invention. The optimum thickness of the recording layer varies depending on the properties of the material used and the purpose of the recording member, and cannot be stated unconditionally, but it is generally 10-0.01.
μ, and 1 to 0.1 μ is a preferable range from the viewpoint of sensitivity and resolution. Further, in the present invention, the support of the HMLBR recording member has no essential influence. That is, when reading information written by HMLBR, whether the support is transparent, translucent, or opaque is set depending on whether transmitted light or reflected light is used. Further, since the physical quantities such as heat capacity and reflectance of the support are limited depending on the intensity of the laser beam used, the material of the support is also determined. The commonly used supports are transparent polymer films such as polyester, polyethylene, acetate, etc.
These include oxide glass, plate-shaped or foil-shaped metals such as A1, and the like.
Furthermore, the applicant has found that the formation of a protective layer brings about the following effects.

That is, when information or images are recorded on an HMLBR recording member in which a recording layer is formed on a transparent support and are read out using transmitted light, all of the information (or images) obtained is observed in such a way that the laser irradiated areas are brighter than the non-irradiated areas. However, according to the present invention, a negative image can also be formed depending on the amount of energy of the irradiated laser light. That is, many of the nonmetallic substances that are the recording layer forming materials of the HMLBR recording member used in the present invention have an absorption edge in the visible range, and therefore, by setting the irradiation laser beam to the relatively short wavelength side of the visible range, , it is possible to easily form a translucent recording layer that has sufficient absorption for recording at the wavelength of the laser light and has a relatively low optical density under white light. When recording is performed on the HMLBR recording member used in the invention at a level higher than the normal recording energy level and at a level that does not cause significant deformation of the protective layer, unlike normal recording, the optical density of the laser irradiated area is different from that of the unirradiated area. If the reading is higher than that, that is, by transmitted light, a negative image is obtained. Although the details of this reason are still unclear, it can be considered as follows. That is, as mentioned above, HMLBR utilizes the deformation of the recording layer due to melting and/or evaporation, and although the phenomena of melting and evaporation usually coexist, when the energy of the laser beam increases, , it is thought that the rate of evaporation increases, and therefore, from this fact, the reason for the increase in the optical density in the laser irradiated area is that the evaporated recording layer-forming substance is deposited on the surface of the protective layer on the recording layer side. Due to condensation, light scattering increases compared to the thin film state of the non-irradiated area.Secondly, the material composition of the laser irradiated area changes due to the difference in vapor pressure of the constituent elements of the non-metallic substance that is the recording layer forming material. For example, if the state changes from a compound to a mixture or the composition ratio of the elements that make up the compound differs, it becomes a different substance with different physical properties, and due to the presence of the protective layer, it does not scatter and can be brought close to the irradiated area. The third reason is that the recording layer forming material reacts with the protective layer forming material due to heat, and the fourth reason is that it depends on the above-mentioned complex phenomenon. EXAMPLES Hereinafter, in order to explain the present invention more specifically, examples will be described along with comparative examples.

Comparative Example 1 A glass disc with a thickness of 2 CTn and a diameter of 30 cm was used as a support, and on one side of the support, chalcogenite glass Ge5Os5O was coated with a film thickness of 1400 to 2000 as a high resolution HMLBR recording member.
Vacuum deposited on λ.

Vapor deposition is carried out using a resistance heating method using a tantalum boat, and the boat temperature during vapor deposition is approximately 700℃, and the degree of vacuum is 5.3 x 10-6.
It was T0rr. HMLBR produced in this way
Recording was performed to use the recording member as a video disc. That is, the glass disk was firmly fixed to one end of a shaft connected to a motor and rotated at about 3000 rpm. Next, laser light from an argon laser (wavelength: 4880 angstroms, output: 200 mW) is introduced into the electro-optical element, FM modulated by a video signal, and then applied to the Ge5Os5O film surface of the recording member using a microscope objective lens with a working distance of about 70 microns. The light was focused on. At this time, the lens was set to move approximately 2 microns in the radial direction per revolution of the glass disk so that signals could be recorded in a spiral manner. When a symbol was recorded using this method, the lens was contaminated with what appeared to be germanium sulfide that had evaporated from the recording medium in the laser irradiation section about 5 seconds after the start of irradiation, and subsequent recording was not possible. Example
1 Ca was added as a protective layer on the Ge5Os5O vapor deposited film of Comparative Example 1.
A recording member was produced by continuously depositing F2 in the same vacuum Persian.

Continuous deposition greatly reduced the amount of dust attached to the surface of the recording layer, and also reduced the time required for fabrication by more than half, compared to the method in which the recording layer and protective layer were deposited separately. The thickness of the CaF2 vapor deposited film was approximately 1.2 μm, and a CaF2 single crystal was used as the vapor deposition source. Next, a micro image was recorded on this recording member using an argon laser (wavelength: 4880 angstroms) at a reduction rate of 1/9. The recording device is about 2 in diameter? The previous recording member was attached to the drum using adhesive tape with the recording layer facing up, and scanning was performed in one direction by rotating the drum.
Scanning in a direction perpendicular to this was performed by moving the microscope objective lens that condenses the laser beam parallel to the axial direction of the drum. The light intensity was modulated using a combination of an electro-optical element and a polarizing plate, and the density of each point of the original image converted into an FM signal was input to the modulation. The recording conditions are: laser beam diameter on the surface of the recording member is approximately 3 microns, scanning speed is approximately 2.5 m/sec, recording time is approximately 1 minute, and the laser light energy to obtain an optimal image with a resolution of approximately 500 lines/m is approximately It was 200mW. When recorded in this manner, good images were obtained, and no destruction of the protective layer was observed within the maximum output of the laser used, 400 mW. Example 2 A recording member was prepared using zinc sulfide as a protective layer on the Ge5Os5O vapor deposited film of Comparative Example 1.

Claims (1)

[Claims] 1 An inorganic material that is transparent to the laser beam used for recording and has excellent mechanical strength is placed on a recording layer of 0.01 to 10 μm made of a nonmetallic material (however, if the nonmetallic material of the recording layer is a chalcogen compound) (excluding chalcogen compounds)
．． A heat mode laser beam recording method, which comprises recording by irradiating a heat mode laser beam recording member provided with a protective layer with a thickness of 1 to 10 microns with a laser beam that does not evaporate or deform the protective layer.