JP3161837B2 - Writing device for thermal recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of writing information by heat conversion by irradiating laser light in different states to a sheet-shaped or roll-shaped heat-sensitive recording material made of a heat-sensitive material capable of repeating writing and erasing of information by heating. The present invention relates to a thermal recording medium writing device for performing erasing and erasing.

[0002]

2. Description of the Related Art Conventionally, a heat-sensitive recording medium in the form of a sheet or a roll, in which writing and erasing of information can be repeated by changing a heating temperature by laser beam irradiation, is performed by mixing a light absorbing material selected from a dye or a pigment. There is a light-absorbing thermosensitive recording medium provided with an anti-reflection layer on the heat-sensitive recording medium, and a heat-sensitive recording medium provided with a light absorbing material in the base material. A writing device that changes the intensity of the oscillation output of a laser light source or the irradiation time of a laser beam to obtain a cloudy state indicating a tone is used.

[0003]

Since the conventional heat-sensitive recording material uses a colored light absorbing material as described above, the heat-sensitive recording material is colored and the contrast is reduced, so that it can be used for color display. In addition, in the writing device, the writing pattern is fixed, the writing operation cannot be performed after confirming the writing pattern, and a stable image quality of the line width cannot be obtained. In addition, there is a problem that erasing unevenness occurs and an erasing operation in a short time cannot be performed.

Accordingly, an object of the present invention is to provide a thermosensitive recording medium capable of performing full-color display by writing by laser beam irradiation,
An object of the present invention is to provide a writing device for a thermosensitive recording medium that can obtain a stable image quality with a line width of a written pattern and can perform an erasing operation in a short time without causing erasing unevenness.

[0005]

According to the present invention, in order to achieve the above object, the invention according to claim 1 is characterized in that a sheet-shaped or roll-shaped thermosensitive recording medium can repeatedly write and erase information. It is made of a heat-sensitive material having a suitable resin base material, performs laser light irradiation movement in the main scanning direction and a sub-scanning direction crossing the recording material, writes information by heat conversion by laser light irradiation, and performs writing. Is a writing device for a thermal recording medium for erasing information written by heat conversion by laser light irradiation with changed energy state, wherein the wavelength of the laser light has an absorption range of the resin base material. It is assumed that. According to a second aspect of the present invention, in the first aspect, the resin base material is made of a vinyl chloride-vinyl acetate copolymer. According to a third aspect of the present invention, in the first aspect of the present invention, when writing information to the thermosensitive recording medium by heat conversion by laser beam irradiation, a preliminary writing is performed, and a detecting means for detecting a pattern thereof is provided. The writing is performed after controlling the laser beam irradiation so that the pattern becomes a desired pattern. According to a fourth aspect of the present invention, in the first aspect of the invention, when erasing information on the thermosensitive recording medium by heat conversion by laser light irradiation, the laser light irradiation is adjusted under the conditions set in the writing device. A means is provided for controlling the movement interval of the laser beam irradiation in the sub-scanning direction according to the width of the pattern on the obtained thermal recording medium. The invention of claim 5 is
2. The apparatus according to claim 1, further comprising means for changing a state of a lens for focusing a laser beam on the thermosensitive recording medium, and changing a state of the lens to change a pattern on the thermosensitive recording medium by laser beam irradiation. It is. According to a sixth aspect of the present invention, in the first aspect, the oscillation member of the laser beam is C
It is made of a mixed gas of O ₂ —N ₂ —He.

[0006]

According to the present invention as described above, the invention of claim 1 is characterized in that the wavelength of the laser light has an absorption range of the resin base material, and the energy of the laser light is efficiently absorbed by the resin base material and the heat is absorbed. After conversion, the thermosensitive material is heated to write and erase information. According to a second aspect of the present invention, in the first aspect of the present invention, the resin base material is made of a vinyl chloride-vinyl acetate copolymer, and the resin base material efficiently absorbs the energy of the laser beam and converts the laser light into heat. The base material is a colorless transparent body, and ensures a cloudy state and a transparent state. According to a third aspect of the present invention, in the first aspect of the invention, when writing information by thermal conversion by laser light irradiation on the thermosensitive recording medium, preliminary writing is performed, and the pattern is detected by the detecting means, and the detection is performed. Writing is performed after laser beam irradiation is controlled so that the pattern becomes a desired pattern. According to a fourth aspect of the present invention, in the first aspect of the invention, when the information on the thermosensitive recording medium is erased by heat conversion by laser beam irradiation, the resin which was initially in a cloudy state according to the temperature of the thermosensitive recording medium. The lens should be adjusted so that the base material can obtain the upper limit of laser light energy that does not damage it, or the resin base material that was initially in a transparent state has a temperature that can be erased with the upper limit of laser light energy. Adjustment is performed, and the CPU controls the movement interval of the laser beam in the sub-scanning direction in accordance with the width of the pattern obtained in that state, thereby performing erasing. According to a fifth aspect of the present invention, in the first aspect of the present invention, a means for changing a state of a lens for focusing a laser beam on the thermosensitive recording medium is provided. The line width of the pattern on the recording medium is changed to a desired one in accordance with writing or erasing.
According to a sixth aspect of the present invention, in the first aspect, the laser beam oscillating member is made of a mixed gas of CO ₂ —N ₂ —He, and the mixed gas oscillates a laser beam suitable for heat conversion of the resin base material. I do.

[0007]

1 to 6 show an embodiment of the present invention. In FIG. 1 showing the writing apparatus 1 of this embodiment, a thermosensitive recording medium 2 (hereinafter, referred to as a recording medium 2) is provided on a frame (not shown) of the writing apparatus 1.
Are provided, and two fixed rails 8 are arranged so as to be parallel to both ends of the fixed rail. A movable rail 9 is mounted so as to be movable along the fixed rail 8 in the sub-scanning direction (Y direction) along the fixed rail 8. The moving rail 9 is locked by a wire 12 stretched over a pulley 11 provided near one end of the fixed rail 8 and a shaft of the first driving motor 10, and the wire 12 is driven by the first driving motor 10 to move the moving rail 9. 9 is reciprocated. A third mirror 13, a lens 6, and a lens driving member 7 are integrally formed on the moving rail 9 to form a lens device 5. The lens device 5 is movably mounted on the moving rail 9, and the lens device 5 is mounted on the moving rail 9. Is fixed to a wire 16 stretched over a pulley 15 provided near one end of the motor and a shaft of the second drive motor 14, and when the wire 16 is driven by the second drive motor 14, the wire 16 moves along the moving rail 9. It reciprocates in the main scanning direction (X direction). The first and second drive motors 10 and 14 are driven by a CPU 17.
Is controlled by The rotation of the first and second drive motors 10, 14 is transmitted by the wires 12, 16, but is not limited thereto, and may be transmitted by a ball screw. In this apparatus, a laser beam is scanned by a raster scan that scans the entire range in which the lens 6 can be moved.
Draw as a raster vector connecting the coordinates with a straight line. In both drawing methods, the light detection device 3 detects a writing position or a separately determined base point in order to perform drawing at an accurate position, and a detection output thereof is input to the CPU 17, and a write command signal is controlled to perform writing. Will be The drive of the first and second drive motors 10 and 14 is C
1st and 2nd motor drive controller 3 by control signal of PU17
It goes through 7,38.

The lens 6 reciprocates in the vertical direction (Z direction) by the lens driving member 7. The driving of the lens driving member 7 is performed via a lens driving controller 39 controlled by a control signal of the CPU 17. The lens 6 is provided in a position parallel to the recording medium 2 placed on the mounting table 25, including a position where the image is formed on the recording medium 2 at its focal point, and at a position where the lens 6 does not hit the recording medium 2 when moved downward. Have been. Although the lens 6 is described as having a fixed focus, it may be of a zoom type, in which case the lens driving member 7 operates to change the focus of the lens.

A light detecting device 3 as a light detecting means shown in FIGS. 2 and 3 and a temperature detecting member 26 are provided on a holding member 27 provided at the lower end of one end of the moving rail 9. One end of the recording body 2 is mounted so as to protrude from the mounting table 25, and the light detection device 3 illuminates the illumination member 28 and the illumination member 28 on the upper surface side of the recording body 2 via the protruding portion of the recording body 2. A temperature detecting member 26 is provided on the mounting table 25 side, which is located on the upper surface side of the recording body 2 and includes a light detecting member 30 provided with a shutter 29 and disposed on the lower surface side of the recording body 2 facing the same. The light detecting member 30 is a CCD contact sensor, and is a line width of the line width pattern 31 written on the recording body 2.
CCD elements are arranged in the width direction of 32. When the laser beam moves to the upper part of the CCD as shown by the dashed line in FIG. 2 to write the spare line width pattern 31, the shutter 29 is closed to protect the CCD and the line width pattern After 31 is written, the shutter 29 is opened and the illumination member 28 is turned on, and the CCD receives the light, and the line width pattern is obtained.
The line width 32 of 31 is detected, and the detection output is input to the light detection circuit 18 to detect the line width 32, and the detection output is input to the CPU 17. The CCD is provided with a light-shielding cover (not shown) to prevent outside light from entering. If the background of the recording medium 2 is transparent and the line width pattern 31 is cloudy, the line width pattern
When the background of the recording medium 2 is clouded, the light detection circuits 18 correspond to each other so that the reverse detection can be performed. The temperature detecting member 26 is the recording body 2
, And the detection output is input to the CPU 17 via the temperature detection circuit 19.

The output of the laser light source 4 is performed by a laser output controller 35 controlled by a control signal of the CPU 17. The laser beam from the laser light source 4 is refracted by a first mirror 33 attached to a machine frame (not shown) and a second mirror 34 attached to one end of the moving rail 9, and a third mirror attached to the lens device 5. At 13, the light is refracted and passes through the lens 6 to irradiate the upper surface of the recording medium 2. Since the laser light is in the infrared region, the mirrors 13, 33, and 34 and the lens 6 are made of a material having low heat absorption and low heat absorption in the infrared region. The mirrors 13, 33 and 34 are made of quartz coated with Ag, and the lens 6 is made of ZnSe coated with an anti-reflection film. An expander that converts laser light into parallel light may be disposed between the laser light source 4 and the first mirror 13.

In this embodiment, the temperature distribution of the heat-sensitive material layer when the recording medium 2 is irradiated with laser light is as shown in the fourth quadrant of FIG. 4, and the irradiation is performed with the same laser light output and the same irradiation time. Then, the lens 6 and the recording medium 2 are determined based on the focal length of the lens 6.
When the distance is increased, the temperature of the solid line decreases to the temperature of the dotted line. It is also possible to increase the laser light output to obtain a temperature distribution as indicated by a dashed line. The thermosensitive material layer is heated at such a temperature to obtain the two states of transparent and cloudy (or cloudy and transparent) visualization at the temperature shown by the solid line and the dotted line or the dashed line. The distance between the lens 6 and the recording medium 2 is made variable, but the same applies when the distance is fixed and the focal length of the lens 6 is made variable. The maximum temperature (Tmax) indicated by the solid line is within a range in which the materials of all the layers constituting the recording medium 2 do not cause thermal damage. The temperature information of the recording medium 2 is also input, and the CPU 17 controls it. Writing information in the temperature state of the solid line indicates that the background of the recording medium 2 is transparent, and writing information in the temperature state of the dotted line indicates that the background of the recording medium 2 is cloudy. The beam diameter a shown in the figure is a transparent pattern with a transparent background, and the beam diameter b is a transparent pattern with a white background.

The writing device 1 can be used for a plotter for CAD, a printer for writing, a direct-view type of a large display, and further has an application as a light projection type film and an application to a display by masking a color filter. . The line width 32 of the line width pattern 31 desired by these applications is approximately 8 to 16 lines / mm for a plotter or a printer for viewing at a clear viewing distance, and 0.1 to 6 lines / mm for a display from a distance. It is about. When the writing density is low, the writing time is shortened. When scanning is performed with a wide beam for erasing, the erasing time is shortened.

The line width 32 of the line width pattern 31 is determined by the beam diameter, and the characteristics of the lens 6 determine the beam diameter to a minimum. The adjustment of the beam diameter to obtain the desired line width 32 is performed by using the lens 6.
The moving distance is uniquely determined by the focal length of the lens 6, but the heating temperature changes depending on the output intensity of the laser beam and the heat storage temperature of the recording medium 2, and as a result, the heat-sensitive material becomes cloudy or transparent. The line width 32 of the line width pattern 31 becomes undesired. Information on the output of the laser beam, the scanning speed of the laser beam, the focal length of the lens 6, and the heat storage temperature of the recording medium 2 is input to the CPU 17 in order to control the line width to a desired value 32. Based on that information,
Processing is performed according to a preset program, and signals for driving the respective driving devices are output. In that step, (1) the CPU 17 determines the distance between the lens 6 and the recording medium 2 by the start signal to position the lens 6, and (2) the temperature information of the recording medium 2 detected by the temperature detecting member 26, If the temperature of the recording medium 2 is high, the laser output is reduced, and if the temperature of the recording medium 2 is low, the CPU 17 controls the laser output controller 35 to increase the laser output so that the laser output becomes the reference laser output. Make the correction,
(3) In this state, the first line width pattern 31 is written, the line width 32 is detected, and if the line width 32 is desired, writing is started. (4) If the detected data line width 32 of the light detecting device 3 is out of a desired allowable value, the laser output is adjusted at a preset level interval, the second pattern is written, and the line width 32 is detected. This operation is repeated until the desired line width 32 is within the allowable value. This control may be performed several times until the writing of one screen is completed, and the pattern has a line width of 32, but may be a dot pattern or another shape.

Although the line width 32 at the time of writing is determined by the writing density, the line width 32 is adjusted within an allowable value, and the lens unit 5 is moved by the moving rail 9 according to the line width 32 to write information. However, the beam diameter at the time of erasing (beam diameter b shown in FIG. 4) has no such restriction, and the CPU 17 determines the line width 32 at the upper limit of the laser output, and sets the Control the drive of the controller to perform the erasing operation. In the case of erasing, the distance between the lens 6 and the recording medium 2 is determined so that the range in which the line width 32 is formed becomes cloudy (or transparent), the lens 6 is fixed, and the recording detected by the temperature detecting member 26 is performed. From the temperature information of the body 2, the CPU 17 corrects the temperature of the reference laser output, and the line width 32 is calculated in this step.
The moving rail 9 is moved in the sub-scanning direction every main scanning at intervals of%, and the entire writing area of the recording body 2 is scanned to perform erasing.

In the embodiment of the present invention, the heat-sensitive material of the recording medium 2 comprises a resin base material and an organic low-molecular substance dispersed in the resin base material, and the resin used for the resin base material forms a film or sheet. It is preferably a colorless, transparent and mechanically stable one.
Polyvinyl chloride; vinyl chloride-based copolymers such as vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, and vinyl chloride-acrylate copolymer Polymer;
Vinylidene chloride copolymers such as polyvinylidene chloride, vinylidene chloride-vinyl chloride copolymer, vinylidene chloride-acrylonitrile copolymer; polyester; polyamide; polyacrylate or polymethacrylate or acrylate-methacrylate copolymer; silicone resin, etc. Yes, these may be used alone or as a mixture of two or more.

The organic low molecular weight substance is preferably a substance which changes from polycrystal to single crystal or vice versa by heating in a heat sensitive material and reversibly repeats a cloudy and transparent state. Those that change at ~ 150 ° C are selected. Such materials include alkanols; alkane diols; halogen alkanols; or halogen alkane diols; alkylamines; alkanes; alkenes; alkynes; halogen alkanes; Or unsaturated mono- or dicarboxylic acids or their esters, amides or ammonium salts; saturated or unsaturated halogen fatty acids or their esters, amides or ammonium salts; halogen allyl carboxylic acids or their esters, amides or ammonium salts; thioalcohols; Thiocarboxylic acids or their esters, amides or ammonium salts; carboxylic acid esters of thioalcohols and the like. These may be used alone or in combination of two or more. The carbon number of these compounds is preferably from 10 to 38, particularly preferably from 10 to 30.

The weight ratio of the resin base material to the organic low-molecular substance is more preferably from 2: 1 to 6: 1. If the ratio of the resin base material is too low, the organic low-molecular substance is contained in the resin base material. If it is difficult to form the film on the retained film, on the other hand, if the ratio of the resin base material is too high, the degree of opacity decreases and the contrast cannot be obtained. Although not shown, the heat-sensitive material made of these materials is applied on a support of a colorless and transparent resin sheet having a thickness of 20 μm to 0.5 mm via an adhesive layer or directly to a thickness of 2 μm to 20 μm to form a layer. Thus, the recording body 2 is formed, and is formed into a sheet or a roll. Further, a protective layer made of a resin layer having high hardness may be provided on the heat-sensitive material layer via an adhesive layer or directly.

The recording medium 2 as described above is capable of repeatedly writing and erasing information by heating, and FIG. 4 shows a visualized state by the heating temperature. The vertical axis of the graph is transparent and cloudy, and the horizontal axis is the temperature at which the recording medium 2 is heated. First, when the temperature of the recording medium 2 in the cloudy state A is raised from room temperature to the temperature T1, the heat-sensitive material changes to the transparent state B. When the temperature-sensitive material at the temperature T1 is lowered to room temperature,
The transparent state B is maintained. After the temperature of the heat-sensitive material is further raised from the temperature T1 to the temperature T2, and when the temperature of the heat-sensitive material is lowered to around room temperature, the temperature changes from the temperature T0 or lower to the cloudy state A, and the cloudy state A is maintained at room temperature. Temperature T
After the temperature rises from 1 to T2, the temperature of the heat-sensitive material returns to room temperature, and two states of visualization can be secured.

The resin material occupies most of the volume in the heat-sensitive material, and the heat in the heat-sensitive material can be effectively heated by absorbing light energy applied to the resin base material. The resin base material in the heat-sensitive material has the above-mentioned characteristics, is capable of forming a film or sheet, has good transparency, is mechanically stable, and is preferable in terms of cost. As the material, there is a vinyl chloride-vinyl acetate copolymer, and the spectrum in the infrared region is shown in FIG. This material is transparent and has no absorption region for light in the visible region. From Figure 5 more than 50%

[Outside 1]

For laser oscillation, a chemical laser, a gas laser,
Semiconductor lasers, liquid lasers, and solid-state lasers are known. Each of these lasers has its own oscillation wavelength,
Select a material that matches the absorption range of the resin base material. Among those oscillating in the infrared region, chemical lasers, gas lasers,
There is a semiconductor laser, and a chemical laser creates an electronically excited state by the chemical reaction of the laser medium by adding energy to the laser medium, thereby inverting the distribution of electronic levels, or the distribution of vibrational rotational levels. Create a reversal 2
There is a type of oscillation condition. The laser that can oscillate in the infrared region is a laser of the type that produces the reversal of the distribution of the vibration rotational level. A typical example of this laser is a hydrogen halide chemical laser, which creates atoms or free radicals and reacts them with molecules by electron beam, ultraviolet light flash, heat from an arc, etc. to cause a chemical reaction in the laser medium. Specifically, the laser oscillates at a wavelength of the HC1 laser (the same applies hereinafter) of 3.6 μm to 4.0 μm. Other than this, some HF lasers oscillate at 2.4 μm to 3.4 μm, and DC1 laser is 5.0 μm with an isotope laser medium.
5.5 μm, DF laser of 3.5 μm to 4.7 μm, and DBr laser of 5.8 μm to 6.3 μm, which match the absorption range of the resin base material. Chemical lasers require equipment to supply and circulate gas.

Semiconductor lasers have a practical wavelength range of about 0.2.
It is 78 μm to 0.90 μm and 1.2 μm to 1.55 μm.Since an alloy having a small interband energy is used to oscillate in the infrared region with a semiconductor laser, it is thermally unstable to form a pn junction. Requires cooling with liquid helium.

A gas laser that oscillates in the infrared region is:
This is a carbon dioxide gas laser using a gas mixture of CO ₂ —N ₂ —He as a laser oscillation member. The oscillation has _two transitions of the vibration level of CO ₂ molecule, which is 9.6 μm to 10.6 μm. In this laser, three kinds of gases of CO ₂ , N ₂ , and He, or a mixed gas to which CO is further added are excited by a DC or AC glow discharge in a closed state without supplying gas. By using this, a laser device which can be used for several thousand hours, has good operability and is inexpensive can be obtained. FIG. 6 shows the relationship between the oscillation wavelength obtained by each type of laser and the absorption region of the resin base material.

The recording body 2 on which the information has been written can be attached to a wall or placed on a desk so that it can be viewed directly, and can be viewed. If the information is written based on the color-separated information, a color image can be obtained by applying a color-separation filter to each color-separated recording medium 2 and projecting it with a light-projecting projector.

[0024]

The present invention is as described above. According to the first aspect of the present invention, there is provided a heat-sensitive material having a resin base material in which a sheet-shaped or roll-shaped recording body can repeatedly write and erase information. The laser beam irradiation is moved in the main scanning direction and the sub-scanning direction crossing the recording body, information is written by heat conversion by laser beam irradiation, and writing is a laser in which the state of energy is changed. In a writing device for a thermosensitive recording medium for erasing information written by heat conversion by light irradiation, the wavelength of the laser light has an absorption range of the resin base material, so that the laser light is efficiently emitted. Absorbed by the resin base material and converted into heat, writing and erasing of information are performed.At this time, there are no members in contact with the recording body, no damage to the recording body, no deterioration and no repeated use. Running There is an effect that theft is reduced. According to a second aspect of the present invention, in the first aspect of the present invention, since the resin base material is made of a vinyl chloride-vinyl acetate copolymer, the laser light is efficiently converted into heat, and the white turbidity and the colorless and transparent state can be secured well. It can be applied to full color and has the effect of expanding the range of devices that can be used. According to a third aspect of the present invention, in the first aspect of the present invention, when writing information by heat conversion by irradiating a laser beam to the recording medium, a preliminary writing is performed, and a detecting means for detecting the pattern is provided. Since the writing is performed after controlling the laser beam irradiation so that the pattern becomes a desired pattern, the writing state can be confirmed in advance, and there is an effect that a good image quality with a stable line width can be obtained. According to a fourth aspect of the present invention, in the first aspect of the invention, when erasing information on a recording medium by heat conversion by laser light irradiation, the laser light irradiation is adjusted under the conditions set in the writing device. By providing a means for controlling the movement interval of the laser beam irradiation in the sub-scanning direction according to the width of the pattern on the recording medium, there is an effect that erasing unevenness does not occur and the erasing time can be shortened. According to a fifth aspect of the present invention, in the first aspect of the present invention, means for changing the state of the lens for focusing the laser light on the recording medium is provided, and the state of the lens is changed to change the state of the lens on the recording medium by laser light irradiation. Since the pattern is changed, there is an effect that writing can be performed with good image quality with stable line width, and erasing can be performed in a short time without causing unevenness in erasing. According to a sixth aspect of the present invention, in the first aspect, the oscillation member of the laser beam is CO ₂ −
Since it is made of a N ₂ -He mixed gas, there is an effect that laser light efficiently absorbed by the resin base material can be oscillated.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic perspective view of the writing device and a block diagram of a drive control system.

FIG. 2 is a schematic perspective view showing a line width pattern, a light detecting device, a temperature detecting member, and second and third mirrors of the same.

FIG. 3 is a schematic vertical sectional view showing a part of the photodetector according to the first embodiment.

FIG. 4 is a characteristic diagram showing a relationship between a thermosensitive material, a beam diameter, and a temperature according to the embodiment of the present invention.

FIG. 5 is a characteristic diagram illustrating a relationship between a wave number and a transmittance of the resin base material.

FIG. 6 is a table showing a correspondence between an absorption wave number of laser light of the resin base material and a laser light oscillation member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Writing device 2 Recording medium 3 Light detection device 4 Laser light source 6 Lens 7 Lens drive member 17 CPU 26 Temperature detection member 31 Line width pattern 32 Line width

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-187452 (JP, A) JP-A-58-214124 (JP, A) JP-A-4-303681 (JP, A) JP-A-4- 182148 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41J 2/32 B41M 5/26 B41M 5/36

Claims (6)

(57) [Claims] 1. A sheet-shaped or roll-shaped heat-sensitive recording material is made of a heat-sensitive material having a resin base material capable of repeating writing and erasing of information, wherein said recording material has a main scanning direction and a sub-scanning direction intersecting the main scanning direction. A thermosensitive recording medium that moves laser light irradiation, writes information by heat conversion by laser light irradiation, and erases information written by heat conversion by laser light irradiation that changes the energy state. Wherein the wavelength of the laser beam has an absorption range of the resin base material. 2. The writing device for a thermosensitive recording medium according to claim 1, wherein the resin base material comprises a vinyl chloride-vinyl acetate copolymer. 3. When writing information on a recording medium by heat conversion by laser beam irradiation, preliminary writing is performed, and a detecting means for detecting the pattern is provided, so that the detected pattern becomes a desired pattern. 2. The writing device for a thermosensitive recording medium according to claim 1, wherein writing is performed after controlling laser beam irradiation. 4. A pattern on a heat-sensitive recording medium obtained by adjusting laser light irradiation under conditions set in a writing device when erasing information on the heat-sensitive recording medium by heat conversion by laser light irradiation. 2. The writing apparatus for a thermosensitive recording medium according to claim 1, further comprising means for controlling a movement interval of the laser beam irradiation in the sub-scanning direction according to the width of the laser beam. 5. A heat-sensitive recording medium further comprising means for changing a state of a lens for focusing laser light on the heat-sensitive recording medium, and changing a state of the lens to change a pattern on the heat-sensitive recording medium by laser light irradiation. Writing device for thermosensitive recording medium. 6. The laser beam oscillating member is CO ₂ —N ₂ —He.
2. The writing device for a thermosensitive recording medium according to claim 1, comprising a mixed gas of: