JPS63279267A - Multiple color printing method for thin metal - Google Patents

Abstract

PURPOSE:To instantaneously execute the multiple color printing of image information in an original onto a surface of a thin metal by means of non-plate printing by pressing a heated metal plate to a band-like belt to which multiple color images are successively transferred to transfer toner images. CONSTITUTION:A toner image is stuck to the surface of a photosensitive body 22 in an intermediate electrophotographic unit 2 by an electrostatic charging device 23, an exposure device 24 and a developing device 25, transferred to the band-like belt 1 by a transfer device 26 and fixed by a fixing device 8. Then, respective color images are similarly formed by units 3, 4. The belt 1 and cylindrical metal plate 51 are held by a press contact roll 53 and a pinch roll 54 in a thermal transfer device 5 and the multiple color images are transferred and melted by heating the images by means of a high frequency induction heating device 52. Thereby, a photoengraving process can be omitted, the matching of respective colors can be accurately executed by a detector 10 and an image similar to a silver salt photographing can be clearly formed on the curved surface of a thin metal.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a multicolor printing method for thin metal. More specifically, the present invention relates to a multicolor printing method for thin metal. This invention relates to a multicolor printing method for thin-walled metals that can be carried out by thermal printing.

(Prior Art) Conventionally, flat plate offset printing and letterpress printing have been used as methods for performing multicolor printing on thin metals such as metal plates and metal foils. In the lithographic offset printing method, ink is applied to the image area of a lithographic plate, which has an oleophilic image area and a hydrophilic non-image area, and then the ink on the flat plate is transferred to a rubber blanket. The letterpress printing method is a method of printing on a printing material, and is a method in which ink is applied to the convex image area on a printing plate, and this ink is printed on the printing material.

Although these conventional printing methods are superior in terms of productivity during mass production, they all require plates, and the plate-making process that precedes printing is time-consuming and labor-intensive, and when printing with multiple colors, it is difficult to register each color. The disadvantage is that it requires time and effort.

In recent years, electronics have progressed in the field of printing, with computers using layout scanners used in the manuscript production stage, and direct plate-making systems being developed in the plate-making process. However, the above-mentioned drawbacks have not yet been solved.

Also, 1iIiI! With the diversification of printing, the demand for high-mix, low-volume printing is increasing, and it has become difficult for conventional printing methods, which lack instant printing capability, to cope with this demand.

On the other hand, as printing techniques that do not use printing plates, when the printing medium is paper, there are so-called non-impact printing techniques such as electrophotography and inkjet methods. These techniques can directly obtain images from computer image output without using printing plates. In particular, electrophotography is used in copiers, facsimile machines, printers, etc., and is attracting attention as a technology that can replace conventional printing.

However, multicolor metal printing using electrophotography has not been put to practical use.

In addition, as a multicolor printing method on curved surfaces, a release agent is applied to a heat-resistant thin plastic film (base film), and a color image is printed on it using offset printing or gravure printing. There is a method of printing an image on a curved surface by placing an image on a base film in close contact with a curved surface and pressing a hot roll against the back side of the base film to melt the thermoplastic resin forming the image.

This thermal transfer printing technology is a method for printing on complex curved surfaces to which printing methods using ordinary plates cannot be applied.

[Problem that the invention seeks to solve]

When applying an electrophotographic method or a thermal transfer printing method as a multicolor printing method to a metal plate, there are the following problems.

In electrophotography, when the printing material is paper, only the surface can be heated because of its low thermal conductivity, and therefore energy consumption is low. In addition, cooling is fast, and multicolor printing can be performed at high speed.

On the other hand, when the printing material is metal, it is difficult to heat only the surface because of its high thermal conductivity, and the entire metal is heated.
Therefore, there is a drawback that energy consumption is large.

In addition, in the case of multicolor printing, it is necessary to cool down to room temperature and print the next color after each printing, making it difficult to increase the speed. The thermal transfer printing method requires a printing plate to form an image on the base film, and there are problems related to the plate-making process and registration for each color as described above, and the expensive base film is disposable. The problem is that you have to do it.

An object of the present invention is to provide an energy-saving, high-speed multicolor printing method for thin metal, which improves the above-mentioned problems.

Another object of the present invention is to provide a multicolor printing method for thin-walled metal, which allows image information of a document stored in a computer to be immediately printed and thermal plate printing is possible.

Still another object of the present invention is to provide a multicolor printing method for thin metal that enables printing on a curved metal plate.

Still another object of the present invention is to provide a method for multicolor printing of thin metals that produces images resembling silver halide photographs.

(Means for Solving the Problems) According to the present invention, a one-color toner image formed by electrophotography on a photosensitive drum is transferred to a moving, replaceable belt and fixed. Toner images of other colors are repeatedly transferred and fixed on the toner image formed on the belt-like belt in the same manner as described above to form a multicolor toner image on the belt-like belt, and then There is provided a multicolor printing method for thin metal, characterized in that the toner image is transferred from a belt-like belt to a metal plate by pressing a heated metal plate. If the metal plate is heated by an induction heating method, faster transfer is possible.

(Function) In the present invention, electrophotography is used to form a multicolor self-made image on a belt-like belt, so the alignment of each color image is performed using a register set on a belt-like belt that moves at a predetermined speed. The alignment point is detected, and the image output from the computer is synchronized with the detection signal to form an image on the photosensitive drum. The photosensitive drum on which the image has been formed and the belt-like belt are fed synchronously, and the image is transferred onto the belt-like belt. By forming images of each color one after another on the belt-like belt in this manner, a multicolor image without positional deviation can be obtained on the belt-like belt. Multicolor printing on a metal plate is performed by thermally transferring this multicolor image onto a metal plate. At this time, if the metal plate is heated by high-frequency dielectric heating, transfer can be performed at an extremely high speed.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a partially cutaway side view of a first embodiment of the present invention. In the figure, reference numeral 1 denotes a belt-shaped belt made of a flexible electrical insulator, which is fed by a feed roller and a guide (not shown) to pass intermediate electrophotographic units 2 and 3 and a final electrophotographic unit 4. A multicolored image is now formed on its surface. This multicolor image is a thermal transfer bag N5
The image is transferred onto a cylindrical metal plate 51. Thereafter, the strip belt is cleaned by a brush 6, further cooled by a cooling device 7, and then goes around. A drum-shaped conductor 2 is provided in the intermediate electrophotographic unit 2.
A layered photoreceptor 22 made of a resin on which vapor-deposited amorphous silicon, vapor-deposited amorphous selenium, or zinc oxide or an organic photoconductor (polyvinyl carbazole, phthalcyanine, etc.) is dispersed rotates in close proximity to the belt-like belt 1. A charging device 23 charges the photoconductor 22 in close proximity to the 22 arIA photoconductors arranged as shown in FIG. A developing device a25 is provided to form an image on the photoreceptor 22, and a transfer device 26 that transfers the toner on the photoreceptor 22 onto the strip/belt 1 using an electric field, and a toner remaining on the photoreceptor 22 is removed by brushing. A cleaning device 27 is provided for removing. Exposure system @2
4 is a laser oscillator 241, an optical modulator 242, and a mirror 24
3. It is composed of a rotating polygon 1244 and an fθ relevator 245, and the laser beam emitted from the laser oscillator 241 is modulated by the optical modulator 242 according to the signal from the image memory, and is then transmitted to a mirror 243, a rotating polygon mirror 244, and an fθ reref. 24
5, the light is focused onto the photoreceptor 22 and scanned in a direction perpendicular to the traveling direction of the photoreceptor 22, thereby forming a charged latent image on the photoreceptor 22 corresponding to the image. In the developing device, brush-shaped spikes formed of magnetic toner on a sleeve that rotates around a permanent magnet rub against the photoconductor 22, and the toner, which is charged to the opposite polarity to the photoconductor 22 due to frictional charging, is removed. It is attached to the photoreceptor 22. The toner is transferred onto the surface of the belt-shaped belt 1 passing very close to the photoreceptor 22 by an electric field applied by the transfer device 26. The dirt remaining on the photoreceptor 22 is removed by a cleaning device 27, and the photoreceptor 22 is uniformly charged again by a charging device 23 for the next printing. The image transferred onto the belt 1 is heated by a fixing device 8 consisting of an infrared lamp and a reflecting mirror and fixed onto the belt 1.The belt 1 is further cooled by a cooling device 9 and transferred to the next intermediate electrophotographic unit 3. sent to. In the cooling device N9, the belt on the side on which no image is formed is brought into contact with a water-cooled metal roll to cool the belt and send the belt to the next medium-wage electrophotographic unit. When forming an image in the intermediate electrophotographic unit, the transparency of the toner is taken into consideration, and in this example, the first intermediate electrophotographic unit 2 uses yellow toner, the second unit 3 uses magenta toner, and the last unit uses yellow toner. 4 uses cyan toner. Intermediate electrophotographic unit 3
The intermediate electrophotographic unit 2 is constructed in the same manner as the intermediate electrophotographic unit 2 except that magenta toner is used. The final electrophotographic unit 4 is constructed similarly to the intermediate electrophotographic unit 2.3, except that cyan toner is used. Each electrophotographic unit is provided with a detection device 10 in front of the photoreceptor 22 in the moving direction of the strip belt 1, and the registration point marked on the strip belt 1 is detected and a detection signal is sent to a computer that controls the exposure device. sent to. A thermal transfer device 5 is provided in the path of the belt 1 after passing through the electrophotographic unit 4 . The thermal transfer device 5 includes a rotary table 50 that rotates intermittently, and a cylindrical metal plate 5 provided on the rotary table 50.
1 and rotates the cylindrical metal plate holding device 55.
55 . . . High frequency induction heating device 52 52 . . . Pressure roller 53 that plunges into the cylindrical metal plate 51 and rotates with the cylindrical metal plate 51 and the strip belt 1 sandwiched between it and the pinch roll 54 . It is composed of The above embodiment is constructed as described above, and its operation will be explained next. The photoreceptor 22 in the intermediate electrophotographic unit 2 is first charged by a charging device 23 so that the photoconductor layer is uniformly charged. Next, when the charged layer is exposed by the exposure device 24 in accordance with the image stored in the memory, a charged latent image corresponding to the image is formed. Yellow toner charged by rIJ frictional charging is attached to the charged latent image thus formed by the developing device 25, and this yellow toner is transferred to the belt-like belt 1 by the action of an electric field in the transfer device 26. Belt 1
The toner image above is the fixing device! At step 8, it is heated and melted using an infrared lamp and fixed onto a belt-like belt. Similarly, in the intermediate electrophotographic unit 3, magenta toner is fixed on the belt in correspondence with the image. Further, in the final electrophotographic unit 4, cyan toner is fixed on the belt-like belt in correspondence with the image, and the belt-like belt 1 on which images have been formed with the three-color toners is sent to the thermal transfer 11iff5. Registration during image formation in each intermediate electrophotographic unit is performed by detecting registration points provided on a belt that moves at a predetermined speed.The detection signal outputs an image signal from the computer, and the image is formed on the drum. Since this is done by an image forming system in which the image on the drum is transferred onto the belt, registration for each image is extremely easy and accurate. Thermal transfer ￥1lt5,
The cylindrical metal plates 51 to be printed are sequentially supplied to the rotary table 50 by a supply device (not shown), sent to a position where they come into close contact with the belt-like belt 1, and then stopped. At this position, the belt-shaped belt 1 and the cylindrical metal plate 51 are pressed together by the pressure roll 53 and the pinch roll 54 in a rolling state. Cylindrical metal plate 5
1 is heated to a desired temperature by a high-frequency induction heating device 52, so that the multicolor image on the belt 1 is transferred to the cylindrical metal plate 51 and fused to its surface.

In the high frequency induction heating device 52, a cylindrical metal plate 51 is placed in a high frequency magnetic field generated by a heating coil through which a high frequency TI flow flows.
By passing it through, an eddy current is induced in the cylindrical metal plate 51, and the cylindrical metal plate 51 is heated to a desired temperature by Joule heat. According to high-frequency induction heating, it is easy to control the temperature of the metal plate 51, which is the object to be heated, and it can be heated uniformly in a short time, so the color image on the belt-shaped belt is extremely well fused to the cylindrical metal plate 51. can. In order to ensure complete transfer by the thermal transfer device, the same type of binder as the binder contained in the toner of the color image is applied on the cylindrical metal plate 51 in advance, and the surfaces of J3 and the belt-shaped belt are coated with toner peeling. Preferably, a release agent is applied to facilitate the removal. FIG. 2 is a side view showing a second embodiment of the present invention, in which the exposure device d24 of the apparatus shown in FIG. 1 is replaced with the exposure device 28 shown in FIG. There is. In the figure, reference numeral 281 denotes a document table on which originals of each color are placed, and reference numeral 282 denotes a light source lamp 283, which is a mirror, which moves at a constant speed from the position indicated by the solid line in the figure to the position indicated by the dashed-dot line during exposure. Similarly, the mirror 284 is moved from the position of the solid line to a point g.
Move to position IIil.

In the second embodiment, when the registration position on the strip belt 1 is detected by the detection device 10, the light source lamp 282,
Mirrors 283 and 284 start moving from the solid line position,
The reflected light from the band-shaped portion of the original on the original platen 281 follows the path along the dashed line in the figure, that is, mirror 283, mirror 284,
The light passes through a lens 285, a mirror 286, and a mirror 287, and is focused onto the photoreceptor 22. In the second embodiment, since the exposure is performed in a band-like manner, the exposure time can be made shorter than in the first embodiment in which the exposure is performed in a dot-like manner. In the second embodiment, the same equipment as in the first embodiment is used except for the exposure device. The developing device 25 is a device that uses a dry developing method in this embodiment, but it adsorbs ions, etc. in an insulating liquid such as petroleum-based or olefin-based solvents such as isoparaffin, carbon tetrachloride, fluorinated chlorinated ethylene, and cyclohexane. A developing device may also be used which disperses and suspends the charged toner particles and causes them to adhere to the photoreceptor layer by Coulomb force due to a latent field. In this embodiment, an endless belt is used as the belt-like belt, but the invention is not limited to this, and a belt supplied in a coiled form may also be used.

Further, in this embodiment, yellow toner is used in the first electrophotographic unit, magenta toner is used in the second unit, and cyan toner is used in the last unit, but the present invention is limited to this embodiment. Various changes can be made without being changed.

For example, a first intermediate electrophotographic unit may use a yellow toner, a second unit a cyan toner, and a final unit a magenta toner. Further, if necessary, the number of intermediate electrophotographic units may be increased from this example to form an image using black toner.

These toners include Disazo Yellow, Cardin 6B,
Pigments such as copper phthalocyanine and carbon black are dispersed in a binder. Further, as the binder, wax, thermoplastic resin, thermosetting resin, etc. are used.

Thermoplastic resins include acrylic resin and polyester resin, while thermosetting resins include epoxy resin,
There are polyurethane resins, etc. Further, although not shown in this embodiment, after the toner image is transferred to the cylindrical metal plate 51, it is preferable to cover the printed surface with a finishing varnish.

〔Effect of the invention〕

Since the metal plate printing method according to the present invention uses electrophotography, there is no need for a plate-making process, and color correction can be easily performed.
Registration for multicolor printing is extremely easy and can be done extremely accurately.

Furthermore, since it is an electrophotographic method, images can be formed on the belt-like belt without applying much pressure compared to printing methods using printing plates, so the belt-like belt that is used repeatedly is not damaged.

Another feature of electrophotography is that the gradation is continuous, and it is possible to obtain fine-grained images similar to those obtained by silver halide photography.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway side view of a first embodiment of the invention, and FIG. 2 is a side view of the second embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Band-shaped belt, 2.3... Intermediate electrophotographic unit, 4... Final electrophotographic unit, 5... Thermal transfer device, 6... Brush, 7... Cooling device, 8... - Fixing device ffi, 9... Cooling device, 10... Detection device, 2
4... Exposure device. Applicant/Applicant's agent Fu Fujimoto Sakiraku 2 Figure

Claims (1)

[Claims] 1. Transferring a one-color toner image formed by electrophotography onto a photosensitive drum onto a moving flexible belt;
After fixing, toner images of other colors are superimposed on the thus formed toner image on the belt-like belt and are transferred and fixed in the same manner as described above to form a multi-colored toner image on the belt-like belt, A multicolor printing method for thin metal, characterized in that the toner image is transferred from the belt-like belt to the metal plate by then pressing a heated metal plate against the belt-like belt. 2. The multicolor printing method for thin metal according to claim 1, wherein the metal plate is heated by an induction heating method.