RU2190534C1 - Method of printing - Google Patents

Abstract

FIELD: simple and decorative printing on different carriers. SUBSTANCE: method includes creation of mirror layer for reflection of laser beams on surface of form cylinder followed by application of layer of paint for forming image by removal of preset points of paint layer by pulses of laser radiation. Action on one and the same volume of paint layer limited by sizes of light spot, incident ray and reflected ray ensures reduction of power of laser radiation sources. EFFECT: possibility of using low-cost radiation sources; increased rate of printing. 7 cl, 5 dwg

Description

Technical field
The present invention relates to printing devices. More specifically, the invention relates to means for printing both the simplest and highly artistic printed products on various types of media.

State of the art
There is a known printing method, which consists in placing the information medium between the printing and printing cylinders, applying a paint layer on the printing cylinder, applying laser pulses to the given points of the paint layer to obtain images on the printing cylinder and transferring it to a medium (RF patent 2100207, cl. 6 B 41 F 9/00).

 In the known method, the paint is removed by laser pulses from all specified points on the surface of the plate cylinder, which are not involved in creating an image transferred to the carrier, causing a light-hydraulic effect for each point in the area of the light spot near the surface of the plate cylinder (opening diploma 65, BI 19 1969) with the subsequent ejection of a drop from this point.

 A printing plate is also known, which is a plate cylinder having a surface in the form of a solid solution or an alloy of a material of its base and a material capable of emitting acoustic pulses under the influence of laser pulses (RF application 2000105959/12, decision to grant a patent dated March 14, 2000) .

 Thanks to such a surface of the mold, the maximum energy release of laser radiation occurs at the boundary between the form and paint and a more efficient emission of droplets of paint of any color. The known method, especially in combination with the specified printing form, allows you to effectively remove ink of any color from predetermined points on the surface of the plate cylinder. However, the energy for droplet ejection from each given point on the surface still remains significant, which does not allow printing using cheap low-power lasers. In addition, droplets escaping from the surface of the plate cylinder complicate the operation of optics focusing laser radiation at given points on this surface.

Disclosure of invention
The basis of the invention is the creation of such a printing method that would drastically reduce the energy required to remove ink from predetermined points on the surface of the plate cylinder, protect the optics of the laser emitters from droplets of ink flying from the surface of the plate cylinder, and use cheap low-power lasers to remove ink at the same time provide the ability to print on both flexible and solid media.

 The problem is solved in that in the printing method, which consists in placing the information medium between the printing and printing cylinders, applying a paint layer on the printing cylinder, applying laser pulses to the given points of the paint layer to obtain images on the printing cylinder and transferring it to the medium, in accordance with the invention, a laser beam at each given point on the plate cylinder is passed through a layer of paint and reflect it from the surface of the cylinder, while the incident and reflected beams follow but within the laser spot, the paint is compacted, ionized, followed by decomposition and removal of the paint from the spot.

 With this printing method, the same laser beam twice affects the ink volume at a given point of the ink layer due to the fact that the laser beam, reflected from the surface of the form, re-enters the same ink volume limited by the size of the laser spot, but from the opposite side . Under the influence of a laser incident beam, the molecules of the paint are compressed and the paint is compacted. The light-hydraulic effect that arose at the interface between the media and the paint under the influence of the incident beam leads to an even greater compaction of the paint in the volume limited by the laser spot. The reflected beam, acting on the compacted paint, ionizes it, causing a chemical reaction of the paint ions with oxygen in the air and, as a result, decomposition of the paint in this volume, the removal of its decay products and the complete release of paint from the surface area of the mold within the laser beam spot.

 It is clear that in order to create images on the surface of the plate cylinder in accordance with the proposed method, it must reflect the pulses of laser radiation with maximum efficiency and be coated with the minimum layer necessary for transferring ink to the carrier. Therefore, it is advisable that a smooth polished mirror is formed on the surface of the plate cylinder to reflect laser beams.

 It is advisable that on the surface of the plate cylinder form a smooth polished mirror to reflect laser beams with many recesses for paint. It is also advisable that when filling in the recesses with paint on the surface of the plate cylinder, it is removed from the spaces between the recesses.

 This embodiment of the printing method will allow even more efficient to remove ink from the recesses that is unnecessary to create an image on the surface of the plate cylinder, and removing ink from the spaces between the recesses will prevent it from smearing on the carrier.

 It is advisable that a smooth polished mirror layer for reflection of laser beams is applied to the elastic surface layer of the plate cylinder.

 This embodiment of the printing method allows you to seal not only flexible media, such as paper, but also hard, such as plastic cards.

 It is advisable that the thickness of the ink layer on the plate cylinder is limited to a value that is minimally necessary for transferring to the carrier and obtaining an image on it.

 This embodiment of the printing method will reduce to a minimum the energy required to remove ink from those points of the ink layer on the plate cylinder that are not involved in the formation of the image on its surface, and therefore will allow the use of low-power, low-cost radiation sources.

 It is advisable that the thickness of the ink layer on the mold is limited to 2-5 microns, which is quite sufficient for transferring ink from the plate cylinder to the carrier.

Brief Description of the Drawings
The invention is further explained in the description of specific, but not limiting, embodiments of the invention and the accompanying drawings, in which
FIG. 1 illustrates the proposed method of printing with a smooth surface of the plate cylinder and its direct interaction with the printing cylinder;
FIG. 2 - the same, with recesses on the smooth surface of the plate cylinder and its direct interaction with the printing cylinder;
figure 3 is a section along II in figure 2;
figure 4 illustrates the proposed printing method in the interaction of the plate cylinder with the printing by means of an intermediate cylinder;
FIG. 5 illustrates the proposed printing method when applying a laser reflective layer to an elastic surface layer of a plate cylinder.

The best embodiments of the invention
The proposed printing method is as follows. The carrier 1 (Fig. 1) is placed between the printing 2 and plate 3 cylinders. A layer 4 is formed on the surface of the plate cylinder 3, which reflects the laser radiation. A thin layer of paint 6 is applied on top of this layer with a roller 5. A laser beam 7 is passed through a layer of paint 6 at each given point of the plate cylinder and reflects it from layer 4 on the surface of cylinder 3. under the influence of incident and reflected rays in the area of the light spot, paint is removed from the reflecting surface 4. The paint remaining on the layer 4 forms a colorful image, which is transferred from the plate cylinder 3 to the carrier 1.

 The removal of paint at each given point of the plate cylinder is carried out strictly within the light spot, which is largely due to the effect of self-focusing - a decrease in the divergence of radiation due to non-linear effects arising from the beam itself. Since in the proposed printing method the same volume of the ink layer in the area of the light spot is exposed from the opposite sides of the incident and reflected rays, in this layer under the influence of the incident beam the ink layer is densified and a transverse gradient of the nonlinear refractive index appears, resulting in the reflected the beam is compressed, which further increases the density of its radiation.

 The proposed method can be implemented both with a smooth surface of the reflective layer 4 with sufficient adhesion of the paint to it, and when performing the reflective layer 4 with many recesses 8 for the paint (figure 2). In this case, the paint is removed from the spaces between the recesses. If the diameter of the spot of the light beam significantly exceeds the diameter of the recess for the paint, then each colorful dot on the carrier is formed by transferring paint to it from the number of recesses on the plate cylinder, which is located within the boundaries of this spot.

 In the case of transferring the image from the plate cylinder to the carrier by means of an intermediate cylinder (FIG. 4), the paint is removed not only from the spaces between the recesses, but also its remnants 9 after sealing the carrier from this cylinder. According to the proposed printing method, a hard medium 10 can be sealed (Fig. 5). For this, the laser reflecting layer 4 is applied to the elastic surface layer II of the plate cylinder 3.

Industrial applicability
The printing method is intended for high-quality printing without changing printing plates on any type of media with minimal energy costs for creating a colorful image on a printed form and minimum power of pulsed light sources.

Claims (7)

 1. The printing method, which consists in placing the information medium between the printing and printing cylinders, applying a paint layer to the printing cylinder, applying laser radiation pulses to predetermined points of the ink layer to obtain images on the printing cylinder and transferring it to a medium, characterized in that the laser beam at each given point of the plate cylinder they pass through a layer of paint and reflect it from the surface of the cylinder, while the incident and reflected rays sequentially compact the paint within the laser spot, ionize it, followed by decomposition and removal of paint from the area of this spot.  2. The printing method according to claim 1, characterized in that a smooth polished mirror is formed on the surface of the plate cylinder to reflect laser beams.  3. The printing method according to any one of claims 1 and 2, characterized in that a smooth polished mirror is formed on the surface of the plate cylinder to reflect laser beams with many recesses for paint.  4. The printing method according to any one of claims 1 and 3, characterized in that when ink is filled in the recesses on the surface of the plate cylinder, it is removed from the spaces between the recesses.  5. The printing method according to any one of claims 1 to 3, characterized in that a smooth polished mirror layer for reflecting laser beams is applied to the elastic surface layer of the plate cylinder.  6. The printing method according to claim 1, characterized in that the thickness of the ink layer on the plate cylinder is limited to a value minimally necessary for transferring to a medium and obtaining an image on it.  7. The printing method according to any one of paragraphs. 1 and 6, characterized in that the thickness of the ink layer on the form is limited to 2-5 microns.

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