JP7196591B2 - PRINTING DEVICE, PRINTING METHOD AND PRINT CONTROL PROGRAM - Google Patents

Description

The present invention relates to a printing device, a printing method, and a print control program.

2. Description of the Related Art Today, there is known an image recording apparatus that subjects a recording target to processing processing or laser processing such as an image by heating the recording target by irradiating it with a laser beam. Such an image recording apparatus has, for example, a laser irradiation device in which a plurality of semiconductor lasers are arranged in an array. image recording and the like.

Patent document 1 (Japanese Patent Application Laid-Open No. 6-183039) discloses a technique for detecting the temperature and humidity of a thermosensitive recording medium and controlling the output of laser light.

However, the conventional method of absorbing laser light into the recording layer of the thermal recording medium to generate heat and color the thermal recording medium, even if the output of the laser light is controlled at the same level, differs depending on the manufacturer, lot, and type of thermal recording medium. There is a problem that the recording layers have different color development sensitivities and characteristics, making it difficult to obtain a constant print quality.

In addition, due to the heat resistance of the thermal recording medium, if the laser output is excessively increased and the temperature of the medium is raised too high, foreign substances such as smoke or decomposition products will be generated from the medium during laser irradiation, requiring consideration of safety and health. . In addition, when foreign matter or decomposition products are generated, there is a concern that the foreign matter or decomposition products may adhere to the thermal recording medium, adversely affect the amount of laser light absorption, and deteriorate the color development quality.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a printing apparatus, a printing method, and a print control program capable of obtaining a certain print quality.

In order to solve the above-described problems and achieve the object, the present invention provides a printing apparatus for printing by irradiating a recording medium with a laser beam from a laser device, wherein the optical characteristics of the recording medium and the recording Based on the optical characteristics of an irradiation table that faces a laser device that generates laser light across the medium, the intensity of the laser light to be applied to the recording medium is obtained, and the intensity and irradiation time of the laser light are adjusted. and an irradiation control unit for controlling the laser device to irradiate a recording medium with laser light based on the intensity and irradiation time adjusted by the adjustment unit, wherein the adjustment unit controls the surface of the recording medium. Let R1 be the energy ratio of the laser beam reflected by the recording medium, and R2 be the energy ratio of the laser beam that is transmitted through the recording medium, reflected by the irradiation table, and transmitted through the recording medium again. Let T be the energy ratio of the laser beam that passes through the irradiation table, P be the intensity of the laser beam that irradiates the recording medium, and t be the irradiation time per predetermined area of the laser beam,
C={1−(R1+R2+T)}×(P×t)
and adjust the value of (P×t) so that the value of C is constant.

ADVANTAGE OF THE INVENTION According to this invention, it is effective in the ability to obtain fixed printing quality.

FIG. 1 is a perspective view of an image recording system according to an embodiment. FIG. 2 is a perspective view showing the configuration of a recording device provided in the image recording system of the embodiment. FIG. 3 is an enlarged view of the optical fiber provided in the recording device. FIG. 4 is an enlarged view of the vicinity of the array head. FIG. 5 is a diagram showing an example of arrangement of array heads. FIG. 6 is a diagram showing an example of arrangement of array heads. FIG. 7 is a diagram showing an example of arrangement of array heads. FIG. 8 is a diagram showing an example of arrangement of array heads. FIG. 9 is a diagram showing an example of arrangement of array heads. FIG. 10 is a block diagram of an image recording system. FIG. 11 is a diagram showing a modification of the image recording system of the embodiment. FIG. 12 is a diagram showing a modification of the image recording system of the embodiment. FIG. 13 is a functional block diagram of the image recording system of the embodiment. FIG. 14 is a cross-sectional view for explaining the positional relationship between the optical head and the irradiation table of the recording apparatus. FIG. 15 is a cross-sectional view of a thermosensitive recording medium. FIG. 16 is a diagram for explaining the relationship between the optical characteristics and the absorptivity when a thermal recording medium is irradiated with a laser. FIG. 17 is a diagram for explaining laser output control of the image recording system according to the embodiment. FIG. 18 is a diagram showing the relationship between the ratio of the energy absorbed by the thermal recording medium and the image density when a solid image is printed, for each thermal recording medium having a different print layer structure and for each irradiation table having a different material. be. FIG. 19 is a flow chart showing the flow of laser control operation of the image recording system according to the embodiment.

An image recording system according to an embodiment, which is an application example of a printing apparatus, a printing method, and a printing control program, will be described below.

An image recording system (an example of a printing apparatus) according to an embodiment records an image by irradiating a recording target with a laser beam. An “image” is information that can be visually recognized, and can be appropriately selected depending on the purpose. That is, the "image" includes, for example, characters, symbols, lines, figures, solid images, or combinations thereof, barcodes, two-dimensional codes such as QR codes (registered trademark), and the like.

A recording object (an example of a recording medium) is not particularly limited as long as it can be recorded with a laser beam, and can be appropriately selected according to the purpose. Any recording object can be used as long as it can absorb light, convert it into heat, and form an image. Examples of the recording object include a thermal recording medium, a structure having a thermal recording portion, and the like.

The heat-sensitive recording medium comprises a support, an image recording layer on the support, and other layers if necessary. Each of these layers may have a single layer structure or a laminated structure, and may be provided on the other side of the support.

(Image recording layer)
Examples of the image-recording layer include those containing a leuco dye and a developer and, if necessary, other components.

The leuco dye is not particularly limited and can be appropriately selected according to the purpose from those commonly used in heat-sensitive recording materials. Leuco compounds of dyes such as spiropyran and indolinophthalide dyes are preferably used.

As the color developer, various electron-accepting compounds that cause the leuco dye to develop color upon contact, oxidizing agents, and the like can be used.

"Other components" include binder resins, photothermal conversion materials, heat-fusible substances, antioxidants, light stabilizers, surfactants, lubricants, fillers, and the like.

(support)
The shape, structure, size, etc. of the support are not particularly limited, and can be appropriately selected according to the purpose. Examples of the shape include a flat plate shape. The structure may be a single layer structure or a laminated structure. The size can be appropriately selected according to the size of the thermal recording medium.

(Other layers)
"Other layers" include a photothermal conversion layer, a protective layer, an under layer, an ultraviolet absorbing layer, an oxygen barrier layer, an intermediate layer, a back layer, an adhesive layer, an adhesive layer, and the like.

A thermosensitive recording medium can be processed into a desired shape according to its use. Examples of the shape include card-like, tag-like, label-like, sheet-like, and roll-like shapes. Card-shaped cards include, for example, prepaid cards, point cards, and credit cards. Those processed into a tag-like size smaller than the card size can be used as a price tag or the like. Moreover, those processed into a tag-like size larger than the card size can be used for process control, shipping instructions, tickets, and the like. Since labels processed into labels can be affixed, they can be processed into various sizes and affixed to trolleys, containers, boxes, containers, etc. that are repeatedly used, and used for process management, product management, etc. can. In addition, the sheet size larger than the card size can be used for general documents, instructions for process control, etc., because the range for recording images is widened.

The thermal recording portion of the structure includes, for example, a portion where a label-like thermal recording medium is attached to the surface of the structure, a portion where a thermal recording material is applied to the surface of the structure, and the like. Moreover, the structure having the thermal recording portion is not particularly limited as long as it has the thermal recording portion on the surface of the structure, and can be appropriately selected according to the purpose. Examples of structures having a thermal recording unit include various products such as plastic bags, PET bottles, and canned foods, transport containers such as cardboard and containers, work-in-process products, industrial products, and the like.

(Configuration of image recording system)
As an example, an image recording system for recording an image on a container for transportation to which a thermal recording label is attached, which is a structure having a thermal recording portion as a recording object, will be described below.

FIG. 1 is a perspective view of an image recording system 100 according to an embodiment. In the following description, the transport direction of the transport container C is defined as the X-axis direction, the vertical direction as the Z-axis direction, and the direction orthogonal to both the transport direction and the vertical direction as the Y-axis direction.

As will be described in detail below, the image recording system 100 irradiates a thermal recording label RL attached to a transportation container C, which is a recording object, with a laser beam to record an image.

As shown in FIG. 1, the image recording system 100 includes a conveyor device 10, a recording device 14, a system control device 18, a reading device 15, a shielding cover 11, and the like.

The recording device 14 is an example of a laser device, and irradiates the thermal recording label RL with a laser beam to record an image, which is a visible image, on a recording target. The recording device 14 is arranged on the -Y side of the conveyor device 10, that is, on the -Y side of the transport path.

The shielding cover 11 is anodized to have a black porous surface, shields the laser beam emitted from the recording device 14, and reduces diffusion of the laser beam. A portion of the shielding cover 11 facing the recording device 14 is provided with an opening 11a for passing the laser beam. Moreover, in this embodiment, the conveyor device 10 is a roller conveyor, but may be a belt conveyor.

The system control device 18 is connected to the conveyor device 10 , the recording device 14 , the reading device 15 and the like, and controls the entire image recording system 100 . The reading device 15 reads a code image such as a bar code or QR code (registered trademark) recorded on a recording object, as will be described later. Based on the information read by the reading device 15, the system control device 18 verifies whether or not the image is correctly recorded.

(Structure of thermal recording label)
Next, the thermal recording label RL attached to the container C will be described. An image is recorded on the thermosensitive recording label RL, which is a thermosensitive recording medium, by changing the color tone with heat. As the thermosensitive recording label RL, a thermosensitive recording medium capable of image recording once may be used, or a thermoreversible recording medium capable of recording multiple times may be used.

The thermosensitive recording label RL is made of a material that absorbs laser light and converts it into heat (light-to-heat conversion material), as well as a material that causes changes in hue, reflectance, etc. due to heat.

Photothermal conversion materials can be broadly classified into inorganic materials and organic materials. Examples of inorganic materials include particles of carbon black or at least one of metal borides and metal oxides such as Ge, Bi, In, Te, Se, and Cr. As the inorganic material, a material that absorbs light in the near-infrared wavelength region to a large extent and absorbs light in the visible wavelength region to a small extent is preferable. For example, metal borides and metal oxides can be used. At least one selected from, for example, hexaboride, tungsten oxide compound, antimony tin oxide (ATO), indium tin oxide (ITO), and zinc antimonate is suitable as the inorganic material.

Hexaborides include, for example, LaB6, CeB6, PrB6, NdB6, GdB6, TbB6, DyB6, HoB6, YB6, SmB6, EuB6, ErB6, TmB6, YbB6, LuB6, SrB6, CaB6, (La, Ce)B6, etc. mentioned.

As the tungsten oxide compound, for example, as described in International Publication No. 2005/037932 pamphlet, Japanese Patent Application Laid-Open No. 2005-187323, etc., the general formula: WyOz (where W is tungsten, O is oxygen, 2.2 ≦z/y≦2.999), or the general formula: MxWyOz (where M is H, He, alkali metal, alkaline earth metal, rare earth element, Mg, Zr, Cr , Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F , P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and one or more elements selected from I, W is tungsten, O is oxygen , 0.001≦x/y≦1 and 2.2≦z/y≦3.0).

Among these, cesium-containing tungsten oxide is particularly preferable as the tungsten oxide compound because it has high absorption in the near-infrared region and low absorption in the visible region.

As the tungsten oxide compound, among antimony tin oxide (ATO), indium tin oxide (ITO), and zinc pre-tintimate, ITO is particularly preferable because it has high absorption in the near-infrared region and low absorption in the visible region. . These are formed in layers by a vacuum deposition method or by adhering a particulate material with a resin or the like.

As the organic material, various dyes can be appropriately used depending on the light wavelength to be absorbed. Dyes are used. Specifically, organic materials include cyanine dyes, quinone dyes, quinoline derivatives of indonaphthol, phenylenediamine nickel complexes, and phthalocyanine dyes.

The photothermal conversion material may be used singly or in combination of two or more. Further, the photothermal conversion material may be provided on the image recording layer or may be provided on a layer other than the image recording layer. When the photothermal conversion material is used in a layer other than the image recording layer, it is preferable to provide a photothermal conversion layer adjacent to the thermoreversible recording layer.

The photothermal conversion layer contains at least a photothermal conversion material and a binder resin.

As a material that changes hue, reflectance, etc. by heat, known materials such as a combination of an electron-donating dye precursor and an electron-accepting color developer used in conventional thermal paper can be used. In addition, materials that change hue, reflectance, etc. due to heat include materials that undergo a compound reaction between heat and light, such as a discoloration reaction that accompanies solid-state polymerization due to heating of a diacetylene compound and irradiation of ultraviolet light. included.

(Configuration of recording device)
FIG. 2 is a perspective view showing the configuration of the recording device 14. As shown in FIG.

As the recording device 14, a plurality of laser emitting portions of optical fibers are arranged in an array in the main scanning direction (Z-axis direction) perpendicular to the sub-scanning direction (X-axis direction), which is the movement direction of the container C, which is the object to be recorded. Arranged and formed (fiber array). Such a recording device 14 irradiates a recording target with laser light emitted from a laser light emitting element via a fiber array to record an image made up of drawing units. Specifically, the recording device 14 includes a laser array section 14 a , a fiber array section 14 b and an optical section 43 . The laser array section 14a includes a plurality of laser light emitting elements 41 arranged in an array, a cooling unit 50 for cooling the laser light emitting elements 41, and a laser light emitting element 41 provided corresponding to the laser light emitting element 41 to drive the corresponding laser light emitting element 41. and a controller 46 for controlling the plurality of drivers 45 . The controller 46 is connected to a power source 48 for supplying power to the laser light emitting element 41 and an image information output section 47 such as a personal computer for outputting image information.

The laser emitting element 41 can be appropriately selected according to the purpose, and for example, a semiconductor laser, a solid-state laser, a dye laser, or the like can be used. Among these, the laser light emitting element 41 is preferably a semiconductor laser because of its wide wavelength selectivity, its small size, which allows the size of the device to be reduced, and the fact that the price can be reduced.

The wavelength of the laser light emitted by the laser light emitting element 41 is not particularly limited and can be appropriately selected according to the purpose. is more preferred.

In the laser light emitting element 41, the applied energy is not entirely converted into laser light. Normally, the laser light emitting element 41 generates heat by converting energy that is not converted into laser light into heat. Therefore, the cooling unit 50 cools the laser emitting element 41 . In addition, the recording device 14 uses the fiber array section 14b, so that the laser light emitting elements 41 can be arranged separately. As a result, the influence of heat from the adjacent laser light emitting elements 41 can be reduced, and the laser light emitting elements 41 can be efficiently cooled. Therefore, it is possible to avoid temperature rise and variation in the laser light emitting element 41, reduce output variation of laser light, and improve density unevenness and white spots.

Note that the output of laser light is the average output measured by a power meter. There are two types of laser light output control methods, namely, a method of controlling the peak power and a method of controlling the pulse emission ratio (duty: laser emission time/cycle time).

The cooling unit 50 is of a liquid cooling type that circulates a coolant to cool the laser light emitting elements 41, and includes a heat receiving portion 51 in which the coolant receives heat from the laser light emitting elements 41 and a heat radiating portion that dissipates the heat of the coolant. 52. The heat receiving portion 51 and the heat radiating portion 52 are connected by cooling pipes 53a and 53b. The heat-receiving part 51 is provided with a cooling pipe through which a coolant flows, which is made of a good heat-conducting member, inside a case made of a good heat-conducting member. A plurality of laser emitting elements 41 are arranged in an array on the heat receiving portion 51 .

The radiator 52 includes a radiator and a pump for circulating coolant. The cooling liquid sent out by the pump of the heat radiating section 52 flows into the heat receiving section 51 through the cooling pipe 53a. Then, the heat of the laser light emitting elements 41 arranged in the heat receiving part 51 is removed while moving through the cooling pipe in the heat receiving part 51 to cool the laser light emitting elements 41 . The cooling liquid that has flowed out of the heat receiving portion 51 and has increased in temperature by taking heat from the laser light emitting element 41 moves inside the cooling pipe 53b, flows into the radiator of the heat radiating portion 52, and is cooled by the radiator. The coolant cooled by the radiator is pumped out to the heat receiving portion 51 again.

The fiber array section 14b includes a plurality of optical fibers 42 provided corresponding to the laser light emitting elements 41, and the vicinity of the laser emission section 42a (see FIG. 4) of the optical fibers 42 arranged in an array in the vertical direction (Z-axis direction). and an array head 44 to hold. A laser incident portion of each optical fiber 42 is attached to a laser emitting surface of the corresponding laser emitting element 41 .

(Configuration of optical fiber)
3 is an enlarged view of the optical fiber 42, and FIG. 4 is an enlarged view of the vicinity of the array head 44. FIG.

The optical fiber 42 is an optical waveguide for laser light emitted from the laser light emitting element 41 . The shape, size (diameter), material, structure, etc. of the optical fiber 42 are not particularly limited and can be appropriately selected according to the purpose.

The size (diameter d1) of the optical fiber 42 is preferably 15 μm or more and 1000 μm or less. When the diameter d1 of the optical fiber 42 is 15 μm or more and 1000 μm or less, it is advantageous in terms of image definition. As an example, the image recording system 100 of the embodiment uses an optical fiber with a diameter of 125 μm as the optical fiber 42 .

The material of the optical fiber 42 is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include glass, resin, quartz, and the like.

As for the structure of the optical fiber 42, it is preferable to have a structure comprising a central core portion through which laser light passes and a clad layer provided on the outer periphery of the core portion.

The diameter d2 of the core portion is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 10 μm or more and 500 μm or less. The image recording system 100 of the embodiment uses an optical fiber having a core diameter d2 of 105 μm. The material of the core portion is not particularly limited and can be appropriately selected according to the purpose. Examples thereof include glass doped with germanium or phosphorus.

The average thickness of the clad layer is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 10 μm or more and 250 μm or less. The material of the clad layer is not particularly limited and can be appropriately selected according to the purpose. Materials for the cladding layer include, for example, glass doped with boron or fluorine.

As shown in FIG. 4, the vicinity of the laser emitting portions 42a of the optical fibers 42 is held in an array by an array head 44 so that the pitch of the laser emitting portions 42a of the optical fibers 42 is 127 μm. In the recording device 14, the pitch of the laser emitting portions 42a is set to 127 μm so that an image with a resolution of 200 dpi can be recorded.

If one array head 44 were to hold all the optical fibers 42, the array head 44 would be elongated and easily deformed. As a result, it becomes difficult for a single array head 44 to maintain the linearity of the beam arrangement and the uniformity of the beam pitch. Therefore, it is assumed that the array head 44 holds 100 to 200 optical fibers 42 . In addition, a plurality of array heads 44 holding 100 to 200 optical fibers 42 are arranged side by side in the Z-axis direction, which is a direction perpendicular to the conveying direction of the container C, so that the recording device 14 can be preferably configured. In the image recording system 100 of the embodiment, 200 array heads 44 are arranged side by side in the Z-axis direction.

(Arrangement of array head)
5 to 9 are diagrams showing an example of arrangement of the array head 44. FIG.

FIG. 5 shows an example in which a plurality of array heads 44 of the fiber array section 14b in the recording device 14 are arranged in an array in the Z-axis direction. FIG. 6 shows an example in which a plurality of array heads 44 of the fiber array section 14b in the recording device 14 are arranged in a zigzag pattern.

From the standpoint of ease of assembly, it is preferable to arrange the plurality of array heads 44 in a zigzag manner as shown in FIG. 6 rather than linearly arranging them in the Z-axis direction as shown in FIG.

FIG. 7 shows an example in which a plurality of array heads 44 of the fiber array section 14b in the recording device 14 are arranged to be inclined in the X-axis direction. By arranging the plurality of array heads 44 as shown in FIG. 7, the pitch P in the Z-axis direction of the optical fibers 42 can be made narrower than the arrangement shown in FIGS. 5 and 6, thereby achieving higher resolution. can be done.

8 shows two array head groups in which a plurality of array heads 44 of the fiber array section 14b in the recording device 14 are arranged in a zigzag pattern, arranged in the sub-scanning direction (X-axis direction), and one array head In this example, one group is shifted from the other array head group by half the arrangement pitch of the optical fibers 42 of the array head 44 in the main scanning direction (Z-axis direction). By arranging the plurality of array heads 44 as shown in FIG. 8, the pitch P in the Z-axis direction of the optical fibers 42 can be made narrower than in the arrangement shown in FIGS. can be done.

By the way, the recording device 14 of the image recording system 100 according to the embodiment prints the thermal recording label RL attached to the transportation container C, which is the object to be recorded, under the control of the system control device 18 shown in FIG. It transmits and records image information in a direction perpendicular to the scanning direction. Therefore, if there is a difference between the timing of scanning the thermal recording label RL and the timing of transmitting image information in the orthogonal direction, the recording apparatus 14 accumulates the image information in the memory, so that the image accumulation amount increases. Become. In such a case, the arrangement example of the plurality of array heads 44 shown in FIG. 8 can reduce the amount of information stored in the memory of the system controller 18 rather than the arrangement example of the plurality of array heads 44 shown in FIG. .

Further, FIG. 9 shows an example in which two array head groups in which a plurality of array heads 44 shown in FIG. 8 are arranged in a staggered manner are laminated as one array head group. The array head 44, in which two such array head groups are stacked as one array head group, can be easily produced in terms of manufacturing, and high resolution can be achieved. In addition, the arrangement example of the array heads 44 shown in FIG. 9 can reduce the amount of information stored in the memory of the system controller 18 more than the arrangement example of the plurality of array heads 44 shown in FIG.

As shown in FIG. 2, the optical unit 43 includes a collimating lens 43a that converts divergent laser beams emitted from the optical fibers 42 into parallel beams, and a surface of the thermosensitive recording label RL, which is a laser irradiation surface. and a condensing lens 43b for condensing the laser light. Whether or not to provide the optical section 43 may be appropriately selected depending on the purpose.

An image information output unit 47 such as a personal computer inputs image data to the controller 46 . The controller 46 generates a drive signal for driving each driver 45 based on the input image data. The controller 46 transmits the generated drive signal to each drive driver 45 . Specifically, controller 46 includes a clock generator. The controller 46 transmits a drive signal for driving each driver 45 to each driver 45 when the number of clocks oscillated by the clock generator reaches a specified number of clocks.

Each drive driver 45 drives the corresponding laser light emitting element 41 upon receiving the drive signal. The laser light emitting element 41 emits laser light according to the drive of the driver 45 . The laser light emitted from the laser light emitting element 41 enters the corresponding optical fiber 42 and is emitted from the laser emitting portion 42 a of the optical fiber 42 . The laser light emitted from the laser emitting portion 42a of the optical fiber 42 passes through the collimating lens 43a and the condensing lens 43b of the optical portion 43, and is then irradiated onto the surface of the thermal recording label RL of the container C, which is the object to be recorded. . An image is recorded on the surface of the thermosensitive recording label RL by heating the surface of the thermosensitive recording label RL with the laser beam irradiated thereon.

When a recording device 14 that uses a galvanometer mirror to deflect a laser beam to record an image on a recording object is used, an image such as a character is irradiated with a laser beam so as to be written in one stroke by rotating the galvanometer mirror. to record. Therefore, when recording a certain amount of information on a recording target, there is a problem that the recording cannot be completed in time unless the recording target is stopped.

On the other hand, by using a laser array in which a plurality of laser light emitting elements 41 are arranged in an array like the recording device 14 of the image recording system 100 of the embodiment, ON/OFF of the laser light emitting element 41 corresponding to each pixel can be performed. An image can be recorded on the recording object under control. As a result, even if the amount of information is large, the image can be recorded on the recording object without stopping the transportation of the container C. Therefore, the image recording system 100 of the embodiment can record an image without reducing productivity even when recording a large amount of information on a recording object.

As will be described later, the recording device 14 of the image recording system 100 according to the embodiment records an image on the recording target by irradiating the recording target with laser light to heat the recording target. Since the conventional laser ray recording apparatus does not have the fiber array section 14b, it is necessary to arrange the laser emitting elements 41 in an array at intervals corresponding to the resolution. Therefore, in the conventional laser ray recording apparatus, it is necessary to arrange the laser light emitting elements 41 at a very narrow pitch in order to achieve a resolution of 200 dpi. As a result, in the conventional laser ray recording apparatus, the heat of the laser light emitting element 41 is difficult to escape, and the temperature of the laser light emitting element 41 becomes high.

In the conventional laser ray recording apparatus, when the temperature of the laser light emitting element 41 becomes high, the wavelength and light output of the laser light emitting element 41 fluctuate, making it difficult to heat the recording object to a specified temperature, and thus producing a good image. difficult to obtain. Further, in the conventional laser ray recording apparatus, in order to suppress such a temperature rise of the laser light emitting element 41, it is necessary to reduce the transport speed of the recording object to increase the light emission interval of the laser light emitting element 41, which reduces productivity. It becomes difficult to raise it sufficiently.

Normally, a chiller system is often used for the cooling unit, and in this system, only cooling is performed without heating. Therefore, the temperature of the light source does not become higher than the set temperature of the chiller, but the temperature of the cooling unit 50 and the laser light emitting element 41 which is the laser light source in contact with the cooling unit 50 fluctuates due to the environmental temperature.

On the other hand, when a semiconductor laser is used as the laser light emitting element 41, a phenomenon occurs in which the laser output changes depending on the temperature of the laser light emitting element 41 (the laser output increases as the temperature of the laser light emitting element 41 decreases). In order to control the laser output, the temperature of the laser light emitting element 41 or the temperature of the cooling unit 50 is measured, and the laser output is controlled according to the measurement result to the driver 45 for controlling the laser output. is preferably controlled to perform normal image formation.

On the other hand, the recording device 14 of the image recording system 100 of the embodiment is a fiber array recording device using the fiber array section 14b. By using a fiber array recording device, the laser emitting portions 42a of the fiber array portion 14b can be arranged at a pitch corresponding to the resolution, and the pitch between the laser emitting elements 41 of the laser array portion 14a can be set to a pitch corresponding to the image resolution. no longer need to. As a result, the pitch between the laser light emitting elements 41 can be sufficiently widened, the heat of the laser light emitting elements 41 can be sufficiently radiated, and the laser light emitting elements 41 can be prevented from becoming hot. Therefore, fluctuations in the wavelength and light output of the laser light emitting element 41 can be suppressed, and a good image can be recorded on the recording object. Moreover, even if the light emission interval of the laser light emitting element 41 is shortened, the temperature rise of the laser light emitting element 41 can be suppressed, the transport speed of the container C can be increased, and the productivity can be improved.

(Hardware configuration of recording device)
Further, in the recording apparatus 14 of the present embodiment, the cooling unit 50 is provided to liquid-cool the laser light emitting element 41, so that the temperature rise of the laser light emitting element 41 can be further suppressed. Therefore, the light emission interval of the laser light emitting element 41 can be further shortened, the transport speed of the container C can be increased, and the productivity can be improved.

Although the laser light emitting element 41 is liquid-cooled, the laser light emitting element 41 may be air-cooled using a cooling fan or the like. Liquid cooling has high cooling efficiency and can cool the laser light emitting element 41 well. Air cooling lowers the cooling efficiency, but can cool the laser emitting element 41 at low cost.

Next, FIG. 10 shows a block diagram of the image recording system 100 of the embodiment. The system control device 18 shown in FIG. 10 includes a CPU (Center Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a non-volatile memory, and the like. The system control device 18 performs drive control of each section in the image recording system 100 and various kinds of arithmetic processing. Connected to the system control device 18 are the conveyor device 10, the recording device 14, the reading device 15, the timer 16, the storage device 17, the operation panel 181, the image information output section 47, and the like.

The operation panel 181 has a touch panel display and various keys, displays images, and receives various types of information input by operator's key operations.

The system control device 18 controls the recording device 14 by the operation of the CPU according to a program stored in a storage unit such as a ROM, and the recording device moves relative to the laser irradiation device in a direction different from the predetermined direction. An image is recorded by heating the object to be recorded by irradiating the object with a laser through an optical fiber array.

In addition, the CPU of the system control device 18 operates based on an image recording program (an example of a print control program) stored in a storage unit such as a ROM, etc., based on the optical characteristics of the thermal recording label RL and the irradiation table. , to control the laser output of the recording device 14 . Even when the plurality of thermosensitive recording labels RL have different optical characteristics, it is possible to obtain a constant print quality. Details will be described later.

(Image recording operation (printing operation) of image recording system)
Next, operation of the image recording system 100 will be described with reference to FIG. First, a container C containing cargo is placed on the conveyor device 10 by an operator. The operator places the container C on the conveyor device 10 so that the side surface of the main body of the container C to which the thermal recording label RL is attached is located on the -Y side, that is, so that the side surface faces the recording device 14. .

When the operator operates the operation panel 181 to designate the start of transportation, the operation panel 181 transmits a transportation start signal to the system control device 18 . The system control device 18 that has received the transport start signal drives and controls the conveyor device 10 so as to start transporting the container C. As shown in FIG. As a result, the container C placed on the conveyor device 10 is conveyed toward the recording device 14 by the conveyor device 10 . An example of the transport speed of the container C is 2 m/sec.

A sensor for detecting the container C being transported on the conveyor device 10 is arranged upstream of the recording device 14 in the transport direction of the container C. As shown in FIG. When the container C is detected by this sensor, a detection signal is transmitted from the sensor to the system control device 18 . Time information indicating the time measured by the timer 16 is supplied to the system control device 18 . The system control device 18 starts time measurement based on the time information from the timer 16 at the timing of receiving the detection signal from the sensor. Then, the system control device 18 grasps the timing at which the container C reaches the recording device 14 based on the elapsed time from the reception timing of the detection signal.

When the elapsed time from the reception timing of the detection signal reaches T1 and the container C arrives at the recording device 14, the system control device 18 detects the heat-sensitive recording label RL attached to the container C passing through the recording device 14. A recording start signal is output to the recording device 14 to record the image.

Upon receiving the recording start signal, the recording device 14 emits a laser beam of a predetermined power toward the thermal recording label RL of the container C moving relative to the recording device 14 based on the image information received from the image information output unit 47. Irradiate. As a result, an image is recorded on the thermal recording label RL in a non-contact manner.

The image recorded on the thermosensitive recording label RL (image information transmitted from the image information output unit 47) includes, for example, a character image such as the content of the package contained in the container C, the information on the destination, and the container It is a code image such as a bar code or a two-dimensional code in which information such as the contents of the package stored in C and the information of the transportation destination is coded.

The container C on which the image was recorded while passing through the recording device 14 passes through the reading device 15 . At this time, the reading device 15 reads a code image such as a bar code or two-dimensional code recorded on the thermosensitive recording label RL, and obtains information such as the content of the package contained in the container C and the information on the transportation destination. do. The system control device 18 collates the information obtained from the code image with the image information sent from the image information output unit 47 to check whether the image is recorded correctly. If the image is correctly recorded, the system controller 18 sends the container C to the next process (for example, transport preparation process) by the conveyor device 10 .

On the other hand, when the image is not correctly recorded, the system control device 18 temporarily stops the conveyor device 10 and displays an error message to the effect that the image is not correctly recorded on the operation panel 181 . Further, when the image is not recorded correctly, the system control device 18 may transport the container C to a predetermined transport destination.

(Vibration suppression operation)
Here, when the recording device 14 performs recording processing on the container C vibrating during transportation by the conveyor device 10, this vibration may affect the quality of the image recorded on the thermosensitive recording label RL. There is

For example, the vibration of the container C disturbs the character image recorded on the heat-sensitive recording label RL, which not only impairs the appearance of the character but also makes it difficult for a person to read the information. Also, in the case of a two-dimensional code, there is a possibility that the image may be destroyed by vibration, making it difficult to read the information.

Therefore, when the two-dimensional code is not recorded on the container C, the image recording system 100 sets the vibration amplitude of the conveyor device 10 to 6 mm or less. Further, when recording a two-dimensional code with a line width of 0.375 mm on the container C, the image recording system 100 reduces the amplitude of vibration of the conveyor device 10 to 2 mm or less by the vibration isolation device. Further, when recording a two-dimensional code with a line width of 0.5 mm on the container C, the image recording system 100 sets the vibration amplitude of the conveyor device 10 to 3 mm or less.

By setting the vibration amplitude of the conveyor device 10 to 2 mm or less, both the two-dimensional code and the character image can be recorded on the recording object with good quality. For suppressing the vibration of the conveyor device 10, for example, the conveyor device 10 may be provided with a vibration isolation device.

The image recording system 100 for recording a barcode on a recording object transmits image information for recording the bar of the barcode on the thermosensitive recording label RL in the direction orthogonal to the conveying direction of the container C from the image information output unit 47 . As a result, when the barcode is recorded on the container C, even if the container C vibrates during transportation by the conveyor device 10, the influence of the vibration on the quality of the image recorded on the thermosensitive recording label RL is reduced. be able to.

Also, if the recording device 14 and the conveyor device 10 vibrate at the same time, the image recorded on the thermosensitive recording label RL of the container C is not affected by the vibration. Therefore, the recording device 14 may be attached to the conveyor device 10, or the resonance frequencies of the recording device 14 and the conveyor device 10 may be matched. Further, when the conveyor device 10 is a roller conveyor, each roll moves up and down, and since each roll is not perfectly circular, vibration is likely to occur. However, vibration can be suppressed by using a belt conveyor as the conveyor device 10 .

Also, if the recording target is lightweight or has a large volume, it may move under the influence of air currents when an image is recorded on the thermosensitive recording label RL. Therefore, the image recording system 100 may be provided with a rectifying (windbreak) device.

Further, if the period of vibration of the container C is sufficiently long with respect to the time for recording an image on the thermosensitive recording label RL, even if the amplitude of the vibration of the container C is somewhat large, the vertical movement of the container C during recording of the image can be minimized. The amount of movement in the direction (Z-axis direction) is small, and the effect on image quality is small. Therefore, when it is difficult to sufficiently suppress the vibration amplitude of the container C, the conveyor device 10 may be designed so that the natural frequency of the conveyor device 10 is low.

Further, when an image is recorded on the thermosensitive recording label RL of the container C, which is the object to be recorded, an object may collide with the conveyor device 10, causing sudden vibration. In this case, the container C may vibrate greatly, making it impossible to record a high-quality image on the recording object. In such a case, the conveyor device 10 may be provided with a vibration detection sensor, and the conveyor device 10 may be stopped when the vibration detection sensor detects the vibration of the conveyor device 10 exceeding a specified value.

(Modification)
11 and 12 are diagrams showing modifications of the image recording system 100 according to the embodiment. As shown in FIGS. 11 and 12, the image recording system 100 according to the embodiment may record an image on the thermal recording label RL of the container C, which is the recording target, by moving the recording device 14. . The image recording system 100 of this modified example has a mounting table 150 on which the container C is mounted. The recording device 14 is supported by a rail member 141 so as to be movable in the horizontal direction in the figure.

In the image recording system 100 of this modified example, first, the operator sets the container C on the mounting table 150 so that the surface of the container C to which the thermal recording label RL is attached faces up. After setting the container C, the operation panel 181 is operated to start the image recording process. When the image recording process starts, the recording device 14 located on the left side in FIG. 11 moves to the right side in the drawing as indicated by the arrow in FIG. Then, the recording device 14 irradiates the recording target (the thermal recording label RL of the container C) with a laser beam while moving to the right side in the drawing, and records an image. After recording the image, the recording device 14 located on the right side in FIG. 12 moves to the left side in the drawing as indicated by the arrow in FIG. 12 and returns to the position shown in FIG.

(Decrease in printing quality due to differences in optical characteristics)
Here, as in the image recording system 100 of the embodiment, the heat-sensitive recording medium used in the method in which the recording layer absorbs laser light to generate heat and develop color varies depending on the manufacturer. The thickness and the like are often different. For this reason, the optical characteristics of the printed layer due to the reflection and absorption of light differ for each manufacturer, and even when the same image is formed with the same laser light output control, the color development density differs in the printed layer for each manufacturer's thermal recording medium. cause inconvenience. Also. Since the irradiation tables facing the laser light source through the thermal recording medium also have different optical characteristics, there arises a problem that the color density of the printed layer differs from one irradiation table to another. Due to such a difference in optical characteristics, there is a concern that print quality will vary with respect to thermal recording media after printing.

In the laser printing method, the image recording system 100 according to the embodiment maintains the energy absorbed by the medium during laser light irradiation based on the optical characteristics of the print layer of the medium such as a thermal recording medium and the optical characteristics of the irradiation table. By doing so, the temperature reached to the recording layer is kept substantially constant. As a result, the color densities of the recording layers are made approximately the same for each medium, and a constant print quality is obtained.

Specifically, the storage device 17 shown in FIG. 10 has a laser control program executed by the CPU of the system control device 18 . The storage device 17 also stores medium optical characteristic data and irradiation table optical characteristic data used for calculations for laser control performed based on the laser control program. The medium optical characteristic data is data indicating optical characteristics including light reflectance and light absorption of each medium such as a thermal recording medium. Similarly, the irradiation table optical characteristic data is data indicating the optical characteristics including reflectance and absorptivity of each manufacturer's irradiation table.

An administrator or the like of the image recording system 100 designates a medium such as a thermal recording medium on which printing is to be performed and an irradiation stand to be used for printing via the operation panel 181 . The CPU of the system control device 18 receives the medium optical characteristic data corresponding to the medium designated by the administrator or the like and the irradiation table optical characteristic data corresponding to the irradiation table to be used (placed) from the storage device 17. It is read out and used for calculation for laser control, which will be described later.

In this example, the medium optical characteristic data and the irradiation table optical characteristic data corresponding to the medium and the irradiation table designated by the administrator or the like are read out from the storage device 17 and used for calculation. However, the medium optical characteristic data and the irradiation table optical characteristic data input by the administrator or the like via the operation panel 181 may be used for the calculation, or the medium optical characteristic data and the irradiation table optical characteristic data may be obtained from a database on the network. It may be downloaded and used for calculation.

(Function of image recording system)
FIG. 13 is a functional block diagram of each function realized by executing the laser control program stored in the storage device 17 by the CPU of the system control device 18. As shown in FIG. As shown in FIG. 13, the CPU of the system control device 18 executes a laser control program to obtain a data acquisition unit 61, a time information acquisition unit 62, an adjustment unit 63, a laser control unit 64 (an example of an irradiation control unit). ), and the laser output acquisition unit 65 .

The data acquisition unit 61 acquires from the storage device 17 the medium optical characteristic data and the irradiation table optical characteristic data corresponding to the medium and the irradiation table designated by the administrator or the like. The time information acquisition unit 62 acquires time information from the timer 16 and counts the irradiation time of the laser light. Based on the acquired medium optical characteristic data and irradiation table optical characteristic data, the adjusting unit 63 performs calculations for performing laser control to obtain a certain print quality according to the optical characteristics of the medium and the irradiation table. The laser control unit 64 performs laser control of the recording device 14 based on the calculation result. The laser output acquisition unit 65 acquires laser output information indicating the current laser output, which is fed back from the recording device 14 . This laser output information is used for laser output adjustment by the laser control unit 64 .

(Positional relationship between recording device and irradiation table)
FIG. 14 is a sectional view showing the positional relationship between the recording device 14 and the irradiation table 70. As shown in FIG. The irradiation table 70 is made of, for example, an aluminum material, and is anodized to have a black surface. This structure makes it difficult for the irradiated laser light to scatter. Also, as shown in FIG. 14, the irradiation table 70 is provided facing the recording device 14 via the thermal recording medium RL. The irradiation table 70 supports the thermal recording medium RL during transport, and suppresses variations in the thermal recording medium RL along the transport path. As a result, laser irradiation can be performed at an appropriate position by the recording device 14, and the density, dot size, etc. of the printed image can be stabilized.

The irradiation table 70 also plays a role of blocking the laser light and preventing the laser light from being transmitted to the opposite side. As a result, it is possible to prevent the energy of the laser beam from causing an abnormal temperature rise in the recording device 14 .

(Structure of thermosensitive recording medium)
FIG. 15 is a cross-sectional view of the thermosensitive recording medium RL. As shown in FIG. 15, the thermal recording medium RL has a substrate RL1, a recording layer RL2, a printing layer RL3, and a protective layer (not shown). The base material RL1 is made of PET (Polyethylene Terephthalate), for example, and supports the recording layer RL2. The recording layer RL2 is made of, for example, a color former such as a leuco dye, a developer, a photothermal conversion material, and the like. The recording layer RL2 absorbs the incident laser light with the photothermal conversion material to generate heat, and as the temperature rises, the color developer reacts with the color former to develop color. Thus, an image is formed on the thermal recording medium RL. An image is formed on the recording layer RL2 by a chemical reaction, but the method of forming the image is not limited to this.

The printing layer RL3 forms the background of the image printed on the recording layer RL2, and is formed with a color, material, and thickness selected by the manufacturer of the thermal recording medium RL. Therefore, the color, material and thickness of the printed layer RL3 vary from manufacturer to manufacturer. Also, the print layer RL3 is a layer that is optionally provided when the user uses the image recording system 100 of the embodiment.

In addition, a protective layer may be provided. By providing the protective layer, the image can be retained while preventing permeation of water, chemicals, etc., and rubbing and scraping of the image. Furthermore, a layer or the like that absorbs ultraviolet rays may be provided in order to prevent deterioration of the coloring agent due to ultraviolet rays. Note that the lamination order (arrangement) of the layers from the substrate RL1 to the print layer RL3 may be an order other than the lamination order shown in FIG.

(Relationship between optical characteristics and absorptance at the time of laser irradiation to thermal recording medium)
FIG. 16 is a diagram for explaining the relationship between the optical characteristics of the thermal recording medium RL and the facing irradiation table 70 and the absorptance. In FIG. 16, the thick arrow indicates the path of the laser beam, and the hatched portion of the recording layer RL2 indicates the absorption of heat. A part of the laser light incident from the substrate RL1 side is reflected by the surface of the substrate RL1 and the interface between the substrate RL1 and the recording layer RL2. A portion of the laser light transmitted through the interface between the substrate RL1 and the recording layer RL2 is absorbed as heat in the recording layer RL2, a portion is reflected at the interface between the recording layer RL2 and the printing layer RL3, and the rest is thermally recorded. It penetrates the medium RL. After that, a part of the laser beam incident on the irradiation table 70 is reflected by the surface of the irradiation table 70, and is again incident on the thermal recording medium RL. happens. Others are transmitted through the surface of the irradiation table 70 .

Here, the ratio of the energy of the initially incident laser light reflected by the thermal recording medium RL (the surface of the substrate RL1, the interface between the substrate RL1 and the recording layer RL2, or the area between the recording layer RL2 and the printing layer RL3 The sum of the proportions reflected at the interface) is defined as "R1". Also, let "R2" be the ratio of light transmitted through the thermal recording medium RL, reflected by the irradiation table 70, and transmitted through the thermal recording medium RL again. Further, the ratio of transmission through the thermal recording medium RL and transmission through the surface of the irradiation table 70 is defined as "T". Also, the ratio of the light that first enters the thermal recording medium RL and is absorbed, and the ratio that the light passes through the thermal recording medium RL, is reflected on the surface of the irradiation table 70, and enters the thermal recording medium RL again for the first time and is absorbed. Let the sum of the above be "A".

Since all laser beams other than "R1", "R2" and "T" are absorbed by the thermal recording medium RL, it can be expressed as "R1+R2+T+A=1". Then, "A=1-(R1+R2+T)" is obtained. Note that these parameters "R1", "R2", "T", and "A" are assumed to be the central wavelength of the laser light in the recording device 14, since they may be wavelength dependent. In addition, the laser beam that is reflected twice or more can be ignored because of its small proportion.

Based on the above concept, the absorption rate in the recording layer RL2 of the thermal recording medium RL can be obtained by considering the optical characteristics of the thermal recording medium RL (especially the printed layer RL3) and the irradiation table 70 due to reflection and transmission. As a result, even if the user arbitrarily changes the thermal recording medium RL and the irradiation table 70, A can be obtained in consideration of the influence thereof, and the output of the laser light can be optimally controlled as described later to keep the image quality constant and stable. can be made

(Method for measuring and inputting optical properties)
Next, a method of measuring and inputting the parameters "R1", "R2", and "T" required to obtain the aforementioned "A" will be described. "R1" measures the reflectance of the thermal recording medium RL at the wavelength of the laser light using a spectrophotometer or the like. Since "R2" is the ratio of transmission through the thermal recording medium RL twice and reflection from the irradiation table 70, it is calculated as the product of the square of the transmittance of the thermal recording medium RL and the reflectance of the irradiation table 70. do. Alternatively, in the arrangement of FIG. 16 as the sum of "R1" and "R2", the light reflected by the thermal recording medium RL or the irradiation table 70 is combined with the incident laser light to obtain the reflected ratio. Also good.

“T” is calculated as the product of the transmittance of the thermal recording medium RL and the transmittance of the surface of the irradiation table 70 (1-reflectance may be used). Diffuse reflection may occur due to roughening on the surface of the thermal recording medium RL and the interface between the layers, so reflected light may be collected and measured with an integrating sphere or the like.

The medium optical characteristic data (“R1” and “R2”) and the irradiation table optical characteristic data (“T”) of the thermal recording medium RL are measured in advance by an administrator or the like and stored in the storage device 17. . As described above, parameters such as “R1”, “R2”, and “T” may be input by the administrator via the operation panel 181. FIG. Also, the sum of "R1" and "R2" may be used instead of "R1" and "R2".

Based on the parameters "R1", "R2" and "T", the ratio "A" of the energy absorbed by the thermal recording medium RL can be calculated from the above equation. Also, the laser irradiation time t [s] per unit area is set as follows. That is, when the pitch of one dot is 200 dpi, it becomes 127 [μm]. It is also assumed that the media transport speed is 5 [m/s]. In this case, the laser irradiation time t [s] per unit area is "t=127/5=25.4 [μs]". In addition to the laser irradiation time, for example, the reciprocal of the transport speed of the medium such as the resolution or the thermal recording medium RL may be used.

(laser output control)
FIG. 17 is a diagram showing the relationship between the ratio "A" of the energy absorbed by the thermal recording medium RL calculated by the system control device 18 based on the above equation and the laser output of the recording device 14. As shown in FIG. The system control device 18 controls the recording device 14 so that the laser output P [W] satisfies “A×P×t=5.0×10 ³ [J]”. The left side indicates the Joule heat absorbed per unit area (for example, 1 pitch 127 μm square) of the thermal recording medium RL. This is a value obtained by multiplying the output P [W] of the irradiated laser and the irradiation time t [s] by the rate A of the energy absorbed by the thermal recording medium RL.

The system control device 18 controls the recording device 14 so that this value becomes a constant value as shown on the right side. As a result, even if the material of the print layer RL3 of the thermal recording medium RL or the irradiation table 70 is changed by the user and has different optical characteristics, the thermal recording medium RL absorbs even if the value of "A" changes. The energy can be controlled to be constant.

As a result, the chemical reaction between the color development layer and the color development layer of the recording layer RL2 becomes insufficient when the energy is too small, and the risk of not being able to obtain a sufficient image density can be suppressed. In addition, the risk of image deterioration due to excessive energy reaching the melting point or deterioration temperature of any material in the thermal recording medium RL can be suppressed, and the image density can be stabilized at a constant level.

In this example, the system controller 18 controls A×P×t to be a constant value. Affects image density. Therefore, the left side may be corrected by about ±20% depending on the material in view of the thermal characteristics. As a result, the image density can be further stabilized.

In this example, the system controller 18 changes the laser output P so as to satisfy "AxPxt=5.0x10 ³ [J]", but changes the irradiation time t. may In this case, the system controller 18 changes, for example, the transport speed according to the thermal recording medium RL.

Also, in this example, the wavelength of the laser light of the recording device 14 is 950 nm. Also, the parameters "R1", "R2", "T" and "A" are set according to the color of the print layer RL3, as shown in Table 1 below. Specifically, when the color of the print layer RL3 is a transparent color, the parameter R1 is "0.04", the parameter R2 is "0.48", the parameter T is "0.30", and the parameter A is "0.18". ” and stored in the storage device 17 as medium-specific optical characteristic data or irradiation table optical characteristic data. Similarly, when the color of the printed layer RL3 is red, the parameter R1 is set to "0.04", the parameter R2 to "0.47", the parameter T to "0.29", and the parameter A to "0.20". and stored in the storage device 17 as medium-specific optical characteristic data or irradiation table optical characteristic data.

For the transparent printed layer RL3, the parameter R1, which is the rate of reflection from the thermal recording medium RL, is set to "0.04", but this value is based on substantially all of the laser light. This means that it is a reflection on the surface of the material RL1. On the other hand, in the case of the white printed layer RL3, of the 0.35 parameter R1, 0.04 is the reflection on the surface of the substrate RL1, and the remaining 0.31 is the reflection at the interface between the recording layer RL2 and the printed layer RL3. It is the percentage that is reflected. Thus, it can be seen that the reflection ratio of the laser light varies greatly depending on the color of the printed layer.

(Laser light output control operation)
FIG. 19 is a flow chart showing the flow of laser control operation executed by the system controller 18 based on the laser control program. 18, the operator or the like of the image recording system 100 performs an input for designating or selecting the thermal recording medium RL to be used for printing via the operation panel 181, and performs a printing start operation. Processing starts from S1. In step S1, the data acquisition unit 61 of the system control device 18 shown in FIG. get.

In step S2, the adjustment unit 63 adjusts the ratio of the energy of the light reflected by the laser beam irradiated surface of the thermal recording medium RL to R1, and transmits the thermal recording medium and is reflected by the irradiation table 70. R2 is the ratio of energy of transmitted light, T is the ratio of energy of light transmitted through the surface of the thermal recording medium and irradiation table 70, P [W] is the output of laser light, and irradiation time per area of laser light is As t[s], the calculation shown by the following formula is performed.

C={1−(R1+R2+T)}×(P×t)

Next, in step S<b>3 , the time information acquiring unit 62 starts acquiring time information of the time kept by the timer 16 . Then, in step S4, the laser control unit 64 controls the recording device 14 to start laser light irradiation. In step S<b>5 , the laser output acquisition unit 65 acquires the current laser output value fed back from the recording device 14 . The laser control unit 64 adjusts the value of (P×t) in the above formula while keeping time based on the time information, and controls the laser output so that the value C is substantially constant.

While performing such laser output control, the laser control unit 64 determines in step S6 whether or not the value of C is substantially constant, such as within ±20%. It is determined whether the value of C is substantially constant, such as within ±20%. If it is determined to be substantially constant (step S6: Yes), the process proceeds to step S7, and the laser control unit 64 determines whether or not printing has ended. If it is determined that printing is not finished (step S7: No), the laser control unit 64 returns the process to step S4 to continue laser control. On the other hand, if it is determined that printing has ended (step S7: Yes), the laser control unit 64 ends the processing of the flowchart of FIG.

Next, when the adjustment unit 63 determines in step S6 that the value of C is not substantially constant (step S6: No), the adjustment unit 63 proceeds to step S8 and sets the value of C to be constant. , the value of (Pxt) in the above formula is changed, and the process returns to step S2. Then, the adjustment unit 63 performs the above calculation again based on the changed value of (P×t). The laser control unit 64 performs laser output control based on the result of the second calculation. As a result, the laser output can be controlled so that the value of C is substantially constant.

In this manner, the image recording system 100 according to the embodiment performs laser output control while changing the value of (P×t) so that the value C is substantially constant. As a result, regardless of the optical characteristics of the thermal recording medium RL and the irradiation table 70, the print density of the thermal recording medium RL can be kept constant, and the printing quality can be improved.

(Effect of Embodiment)
As is clear from the above description, the image recording system 100 of the embodiment performs laser control based on the optical characteristics of the thermal recording medium RL and the irradiation table 70, thereby performing various types (optical characteristics) of thermal recording. Corresponding to the medium RL and the irradiation table 70, the print density of the thermal recording medium RL can be stabilized. Therefore, it is possible to improve the print quality.

(Constantization of laser output corresponding to the type of thermal recording medium and irradiation table)
More specifically, FIG. 18 shows the thermal polarities obtained by changing the color and thickness of the printed layer RL3 of the thermal recording medium RL and by changing the material of the irradiation table 70 and performing measurements. 4 is a diagram showing the relationship between the ratio A (parameter A) of energy absorbed by the recording medium RL and the image density (OD); FIG. In FIG. 18, the graph indicated by black circles “●” is the characteristics of a comparative example obtained by setting the irradiation output to be constant (for example, P=3.9 [W]). In the case of this comparative example, it can be seen that the image density increases according to the ratio of the energy absorbed by the thermal recording medium RL. It can be seen that the image density changes when the user arbitrarily changes the thermal recording medium RL or the irradiation table 70 . In particular, when the image density reaches the highest level, scorching occurs due to deterioration of the thermal recording medium RL, resulting in image deterioration.

On the other hand, the graph indicated by white circles "◯" is the characteristics of the image recording system 100 of the embodiment. As can be seen from the graph of the white circles "○", in the case of the image recording system 100 of the embodiment, the image density is 1.0 to 1.2 regardless of how the thermal recording medium RL or the irradiation table 70 is changed. becomes approximately constant within the range of . As a result, the reaching temperature of the recording layer RL2 of the thermosensitive recording medium RL can be made substantially constant, and the color density of the recording layer RL2 can be made approximately the same for each medium such as the thermosensitive recording medium RL, thereby obtaining a constant print quality. be able to.

(Gradation expression)
Further, the image recording system 100 of the embodiment can keep the image density constant regardless of the printing layer RL3, suppress image deterioration, and supply stable image quality. can also provide consistent image quality. The image density depends on the output, and the higher the output, the darker the image obtained. Therefore, the system control device 18 changes the amount of energy on the right side of the above-described arithmetic expression "A×P×t=5.0×10 ³ [J]" according to the gradation. As a result, a constant and stable image quality (print quality) can be obtained at each gradation regardless of the material of the thermal recording medium RL or the irradiation table 70 .

(Stabilization of image density for white print layer)
As described using Table 1, in the case of the thermal recording medium RL in which all or part of the printing layer RL3 is white, part of the laser light is reflected at the interface between the recording layer RL2 and the printing layer RL3, and is recorded again. Pass through layer RL2. This increases the energy absorbed and increases the value of parameter "A" discussed above. As the value of the parameter "A" increases, the energy absorbed by the thermal recording medium RL increases, resulting in different color densities for the thermal recording medium RL having the print layer RL3 of a color other than white.

As described above, the image recording system 100 of the embodiment can stabilize the energy absorbed by the thermal recording medium RL to stabilize the image density. It can be obtained more remarkably with a thermal recording medium RL having a white printed layer with a reflection ratio of 0.10 or more.

In addition, in the description of the above embodiment, the values of the parameters R1, R2, and T that are measured in advance are used. However, all or part of the parameters R1, R2, T, etc. may be measured and used immediately before or during printing. As a result, since the laser can be controlled based on the parameters obtained in real time, it is possible to obtain more stable print quality without being affected by aging of the apparatus.

(Suppression of generation of foreign matter from thermal recording medium)
Also, let us consider that the thermal recording medium (especially the recording layer) is irradiated with an excessive amount of laser light. In this case, there is concern that the temperature of the thermosensitive recording medium will rise to a temperature exceeding the heat resistance, the material of the recording layer will be thermally decomposed, and foreign substances such as smoke and decomposition products will be generated. The applicant of the present invention conducted a prototype test of the image recording system 100 according to the embodiment, and as a result, it was verified that the generation of such foreign matter and decomposed matter can be suppressed.

Therefore, the image recording system 100 according to the embodiment can prevent the inconvenience of handling a thermal recording medium with foreign matter attached to it by an operator in the vicinity of the recording apparatus 14 that irradiates the laser, thereby improving the safety of the system. can be done. In addition, it is possible to prevent the problem that foreign substances or decomposed substances adhere to the transport system of the thermal recording medium and adversely affect the amount of laser light absorbed by the thermal recording medium, resulting in deterioration of the printed image quality. In addition, it is possible to prevent the inconvenience of the generation of foreign matter.

Finally, the above-described embodiments are presented as examples and are not intended to limit the scope of the invention. Each novel embodiment can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. In addition, the embodiments and modifications of the embodiments are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

10 Conveyor Device 11 Shielding Cover 14 Recording Device 14a Laser Array Section 14b Fiber Array Section 15 Reading Device 16 Timer 17 Storage Device 18 System Control Device 41 Laser Light Emitting Element 42 Optical Fiber 42a Laser Emitting Section 43 Optical Section 43a Collimating Lens 43b Condensing Lens 44 Array head 45 Drive driver 46 Controller 47 Image information output unit 48 Power supply 50 Cooling unit 51 Heat receiving unit 52 Heat radiation unit 53a Cooling pipe 53b Cooling pipe 61 Data acquisition unit 62 Time information acquisition unit 63 Adjustment unit 64 Laser control unit 65 Laser acquisition unit 100 Image recording system 141 Rail member 150 Mounting table 181 Operation panel C Container P Pitch of optical fibers in the Z-axis direction (laser irradiation pitch)
RL Thermal recording label

JP-A-6-183039

Claims (5)

A printing device for printing by irradiating a laser beam from a laser device onto a recording medium,
Based on the optical characteristics of the recording medium and the optical characteristics of an irradiation table provided facing the laser device with the recording medium therebetween, the intensity of the laser beam irradiated to the recording medium is obtained, and the recording is performed. an adjustment unit that adjusts the intensity and irradiation time of the laser beam so that the energy absorbed by the medium has a constant intensity;
an irradiation control unit that controls the laser device to irradiate the recording medium with the laser light based on the intensity and irradiation time adjusted by the adjustment unit ;
The adjustment unit
Let R1 be the ratio of the energy of the laser beam reflected on the surface of the recording medium,
R2 is the energy ratio of the laser light that passes through the recording medium, is reflected by the irradiation table, and then passes through the recording medium again;
Let T be the energy ratio of the laser light that passes through the recording medium and the irradiation table,
P is the intensity of the laser beam irradiated to the recording medium;
Assuming that the irradiation time per predetermined area of the laser light is t,
C={1−(R1+R2+T)}×(P×t)
performs the calculation of
Adjusting the value of (P × t) so that the value of C is constant
A printing device characterized by: Furthermore, having a data acquisition unit,
2. The printing apparatus according to claim 1, wherein the data acquisition unit acquires the optical characteristic data of the recording medium and the optical characteristic data of the irradiation table. 3. The printing apparatus according to claim 2, wherein the data acquisition unit acquires the optical characteristic data of the recording medium used for printing and the optical characteristic data of the irradiation table by designating them. A printing method for printing by irradiating a recording medium with a laser beam from a laser device,
Based on the optical characteristics of the recording medium and the optical characteristics of an irradiation table provided facing the laser device with the recording medium interposed therebetween, the intensity of the laser beam irradiated to the recording medium is obtained, and the laser an adjustment step of adjusting the light intensity and irradiation time;
an irradiation control step of controlling the laser device to irradiate the recording medium with the laser beam with the intensity adjusted in the adjusting step ;
In the adjustment step,
Let R1 be the ratio of the energy of the laser beam reflected on the surface of the recording medium,
R2 is the energy ratio of the laser light that passes through the recording medium, is reflected by the irradiation table, and then passes through the recording medium again;
Let T be the energy ratio of the laser light that passes through the recording medium and the irradiation table,
P is the intensity of the laser beam irradiated to the recording medium;
Assuming that the irradiation time per predetermined area of the laser light is t,
C={1−(R1+R2+T)}×(P×t)
performs the calculation of
A printing method , wherein the value of (P×t) is adjusted so that the value of C is constant . A print control program to be executed in a computer having a laser device and having a function of irradiating a recording medium with a laser beam from the laser device to perform printing ,
said computer,
Based on the optical characteristics of the recording medium and the optical characteristics of an irradiation table provided facing the laser device with the recording medium interposed therebetween, the intensity of the laser beam irradiated to the recording medium is obtained, and the laser an adjustment unit that adjusts the intensity and irradiation time of light;
functioning as an irradiation control unit for controlling the laser device to irradiate the recording medium with the laser light based on the intensity and irradiation time adjusted by the adjustment unit ;
The adjustment unit
Let R1 be the ratio of the energy of the laser beam reflected on the surface of the recording medium,
R2 is the energy ratio of the laser light that passes through the recording medium, is reflected by the irradiation table, and then passes through the recording medium again;
Let T be the energy ratio of the laser light that passes through the recording medium and the irradiation table,
P is the intensity of the laser beam irradiated to the recording medium;
Assuming that the irradiation time per predetermined area of the laser light is t,
C={1−(R1+R2+T)}×(P×t)
performs the calculation of
A print control program characterized in that the value of (P×t) is adjusted so that the value of C is constant .

Images