JP2011104640A - Laser printing method and laser printing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser printing method by which, even for an image with a fine gradation, a visually distinguishable image is printed without foaming a workpiece, and to provide a laser printing device using the laser printing method. <P>SOLUTION: Binarized images Pa to Pd obtained by binarizing a gradation image P is generated using different threshold values ThA to ThD set to the lightness (density) of the gradation image P, the generated binarized images Pa to Pd are successively selected one by one and the prescribed range 4 of the workpiece is irradiated with laser beam based on the selected binarized image. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a laser printing method and a laser printing apparatus.

  2. Description of the Related Art Conventionally, there has been provided a laser printing apparatus using a laser printing method that irradiates a laser beam to print a grayscale image such as a character or a figure on a workpiece (for example, Patent Document 1).

  The conventional laser printing method is a photographic printing that irradiates a workpiece with a laser beam once while changing the output power of the laser beam based on the change width of the density of the grayscale image captured in the laser printer. Is expressed.

JP 2003-31447 A

  The print density with respect to the output power of the laser beam is shown in FIG. As shown in the graph G1 of FIG. 11, when the output power of the laser beam is increased, it is possible to print darkly on the work. It should be noted that if the print density is higher than the visual discrimination density K0, it can be visually recognized.

  However, in the conventional laser printing method, depending on the type of resin forming the workpiece, as shown in the graph G2 in FIG. 11, when the output power exceeds the foaming level Pw2 (second level), the workpiece is excessive due to excessive energy. May foam and the quality of the appearance and the like may be deteriorated. Therefore, even if the output power of the laser beam is increased, the work is foamed and not always printed darkly. In addition, when printing a gray image with a fine density gradation and a large change width, it is necessary to increase the output power of the laser beam in a portion where the density is high, but if the output power exceeds Pw2 (first level), the work Foams. Further, it is necessary to reduce the output of the laser beam in the portion where the density is low. However, when the output power is lower than the visual discrimination level Pw1 (first level), the printed density becomes lighter than the visual discrimination density K0, which is visually detected. It becomes impossible to distinguish. Therefore, in the conventional laser printing method, there is a problem that an imperfect image with poor quality is printed when a grayscale image having a small density gradation is printed.

  The present invention has been made in view of the above-described reasons, and its purpose is to perform laser printing that can print an image that can be visually discerned without foaming a workpiece, even if the image has a fine gradation. A method and a laser printing apparatus using the method.

  The invention of claim 1 generates a plurality of binary images obtained by binarizing the grayscale image using a plurality of different threshold values set for the density of the grayscale image, and the generated plurality of binary images are displayed. One image is selected sequentially, and laser light is irradiated to a predetermined range of the workpiece based on the selected binary image.

  According to the present invention, a plurality of binary images having different threshold values are sequentially selected one by one, and laser light is irradiated to a predetermined range of the workpiece based on the selected binary image. Therefore, as the print density increases. The number of times of laser light irradiation increases, and the number of times of laser light irradiation decreases as the print density decreases. Thereby, the density of the printed image can be expressed. Further, since the output power of the laser beam can be set individually, the print density can be adjusted. Therefore, even a grayscale image with a fine density gradation can be printed so as to be visually distinguishable without foaming the workpiece.

  According to a second aspect of the invention, in the first aspect of the invention, the output of at least one of the sequentially irradiated laser beams can be printed with a density that can be discriminated by human vision. The total output of the laser beams that are sequentially irradiated is smaller than the second level at which the workpiece is foamed.

  According to the present invention, it is possible to color the portion that is desired to be expressed most thinly without foaming the portion that is desired to be expressed the darkest.

  The invention according to claim 3 is a laser printer, wherein the threshold value setting means for setting a plurality of different threshold values for the density of the grayscale image, and the binarization of the grayscale image using the plurality of threshold values set by the threshold value setting means, Binary image generating means for generating a plurality of binary images, and sequentially selecting the generated plurality of binary images one by one, and irradiating a predetermined range of the workpiece with laser light based on the selected binary images And a laser beam irradiating means.

  According to the present invention, a plurality of binary images having different threshold values are sequentially selected one by one, and laser light is irradiated to a predetermined range of the workpiece based on the selected binary image. Therefore, as the print density increases. The number of times of laser light irradiation increases, and the number of times of laser light irradiation decreases as the print density decreases. Thereby, the density of the printed image can be expressed. Further, since the output power of the laser beam can be individually set based on the sequentially selected binary images, the print density can be adjusted. Therefore, even a grayscale image with a fine density gradation can be printed so as to be visually distinguishable without foaming the workpiece.

  As described above, the present invention has an effect that even an image with a small gradation can be printed so as to be visually discriminable without foaming a workpiece.

(A)-(d) It is a figure which shows the laser printing process of this invention. It is a figure which shows schematic structure of a laser printing apparatus same as the above. It is a figure which shows a grayscale image. It is a figure which shows the brightness after (a) the brightness of a grayscale image, and (b)-(e) binarization processing. (A)-(d) It is a figure which shows a binary image. It is a figure which shows (a) printing density with respect to output power, and (b) printing density. It is a figure which shows the printing result of a grayscale image. (A)-(c) It is a figure which shows the printing image by the conventional laser printing method. (A)-(c) It is a figure which shows the printing image by the conventional laser printing method. (A) (b) It is a figure which shows the printing image by the laser printing method of this invention. The relationship of print density to output power is shown.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment)
FIG. 2 shows a schematic configuration as an embodiment of the present invention. In this embodiment, a condition setting personal computer 1 (hereinafter referred to as a condition setting PC 1), a laser head 2 that prints by irradiating a laser beam onto a work 4 formed of, for example, an ABS resin, and the laser head 2 are provided. The controller 3 is configured to control the output power and the irradiation location of the laser beam to be irradiated based on the setting of the condition setting PC 1. The condition setting PC 1 includes a grayscale image storage unit 11, a threshold setting unit 12, A binary image generation unit 13, a binary image storage unit 14, and a laser light output setting unit 15 are provided.

  Below, the case where marble-like printing is performed on the workpiece 4 using the laser printing method of the present invention will be described. First, a photograph of marble is taken using a photographing means (not shown). Then, the photograph of the photographed marble shown in FIG. 3 (hereinafter referred to as the gray image P) is stored in the gray image storage means 11 of the condition setting PC 1.

  Then, the threshold setting unit 12 sets four different thresholds ThA to ThD for the brightness (density) of the gray image P stored in the gray image storage unit 11. FIG. 4A shows the brightness of the grayscale image P. Note that whiteness is expressed as the brightness increases, and black is expressed as the brightness decreases. The threshold values ThA to ThD are set in order from the higher (white) brightness of the grayscale image P. Next, the binary image generating means 13 is 0 (black) for a lightness (black) portion lower than each threshold ThA to ThD in the grayscale image P, and 1 (white) for a lightness higher (white) than each threshold ThA to ThD. The binarization process is performed on the grayscale image P, and four binary images Pa to Pd are generated and stored in the binary image storage unit 14.

  FIGS. 4B to 4E show the brightness after binarization using the threshold values ThA to ThD, and FIGS. 5A to 5D show the binary images Pa to Pd. As shown in FIGS. 4B to 4E and FIGS. 5A to 5D, the threshold ThA is created because the brightness is set higher than the other thresholds ThB to ThD. In the binary image Pa, the black portion is the largest and the white portion is the smallest. Conversely, since the threshold value ThD is set to a value that is lighter than the other threshold values ThA to ThC, the generated binary image Pd has the smallest black portion and the largest white portion.

  Next, the laser light output setting means 15 is used to allow the user to determine the laser light irradiation location, laser light output power, etc. based on the binary images Pa to Pd stored in the binary image storage means 14. Set the output conditions. Then, the controller 3 controls the operation of the laser head 2 based on the output condition, and performs printing by irradiating the workpiece 4 with laser light.

  1A to 1D show the printing process. As shown in FIGS. 5A to 5D, the binary images Pa to Pd have a marble pattern. However, in FIGS. .

  First, laser beam output conditions are set using the binary image Pa. As shown in FIG. 1A, a print image Pa ′ is printed by irradiating a portion corresponding to a black portion of the binary image Pa in a predetermined range of the workpiece 4 with a laser beam. FIG. 6A shows the relationship between the output power of the irradiated laser beam and the print density. Since the output power PwA is set to the same value as the visual discrimination density Pw1 (first level) described above, the print density Ka is the thinnest visual discrimination density K0 that can be discriminated by human vision. In the binary image Pa, a portion having a lightness (white) higher than the threshold ThA in the grayscale image P is not printed.

  Next, the laser beam output conditions are set using the binary image Pb. As shown in FIG. 1B, a print image Pb ′ is printed by irradiating a portion corresponding to the black portion of the binary image Pb in the predetermined range of the workpiece 4 with a laser beam. The threshold value ThB used when generating the binary image Pb has a lower brightness (black) than the threshold value ThA used when generating the binary image Pa. Therefore, the laser beam is irradiated based on the binary image Pb. All the portions are portions that have already been irradiated with laser light based on the binary image Pa. Therefore, since the laser beam with the output power PwB is irradiated to the portion that has already been irradiated with the laser beam with the output power PwA, the laser beam is based on the binary image Pb as shown in FIG. The total output power of the laser light in the portion irradiated with is PwA + PwB, and the print density Kb is higher than the print density Ka.

  Similarly, when laser beam output conditions are sequentially set using the binary images Pc and Pd and the predetermined range of the workpiece 4 is sequentially irradiated with the laser beam, the print image Pc is displayed as shown in FIGS. 'And Pd' are printed. As explained above, since the portion that is irradiated with laser light later is the portion that has already been irradiated with laser light, the output power of the laser light in the irradiated portion of the laser light is added, and the print density is high. It will become. Therefore, as shown in FIGS. 6A and 6B, the relationship between the print densities Ka to Kd is Ka <Kb <Kc <Kd, and the density can be expressed.

  Further, the output powers PwA to PwD are set so that the total output power (PwA + PwB + PwC + PwD) of the laser light irradiated based on the binary images Pa to Pd is smaller than Pw2 (second level) where the workpiece 4 is foamed. Therefore, the work 4 is not foamed and quality such as appearance is not deteriorated.

  FIG. 7 shows a print result P ′ of the marble photograph (grayscale image P) shown in FIG. As described above, the binary images Pa to Pd are sequentially selected one by one, the output location of the output location and output power is set based on the selected binary image, and the laser beam is applied to a predetermined range of the work 4. Irradiate. As a result, the number of times of laser light irradiation increases as the print density increases, and the number of times of laser light irradiation decreases as the print density decreases, so that light and shade can be expressed. Further, by setting the output power PwA to be equal to or higher than the visual discrimination level Pw1 (first level), the print density Ka can be made higher than the visual discrimination density K0, so that the portion that is to be expressed lightest can be surely colored. it can. Further, by making the total output power (PwA + PwB + PwC + PwD) smaller than the foaming level Pw2 (second level), the work 4 of the portion that is most strongly expressed is not foamed. Further, by setting a large number of threshold values and increasing the number of binary images, even if the density gradation of the grayscale image P is fine and the density change range is large, it can be visually discriminated without foaming the workpiece 4. Can be printed.

  Further, by using the laser printing method of the present embodiment, it is possible to adjust the change (gradation) of the printing density. In the conventional laser printing method, since the photographic printing is performed by only one irradiation while changing the output of the laser beam based on the change width of the density of the grayscale image, it is possible to change the density of the entire printed image. Although it was possible, the degree of change in print density could not be adjusted. FIGS. 8A to 8C and FIGS. 9A to 9C show printing examples printed by a conventional laser printing method.

  For example, when it is desired to express a thin portion darkly in a print image printed by the conventional laser printing method shown in FIGS. 8 (a) and 9 (a), the conventional laser printing method uses FIGS. 8 (b) and 9 (b). ), The degree of change in the print density does not change, the entire printed image becomes dark, and the output power of the laser beam in the dark portion increases, so that the workpiece 4 may foam. Further, when it is desired to express a dark portion lightly, as shown in FIGS. 8C and 9C, the degree of change in the print density does not change, and the entire printed image becomes thin, and the laser in the originally thin portion is displayed. There is a possibility that visual discrimination cannot be performed due to a reduction in the output power of light.

  However, in the present embodiment, the degree of change in print density (gradation) can be adjusted by individually adjusting the laser light output powers PwA to PwD based on the binary images Pa to Pd. For example, when it is desired to express a thin portion deeply, when setting the output condition based on the binary image Pa, the output power PwA of the laser beam is set larger than the visual discrimination level Pw1 (first level). As shown in 10 (a), only a thin portion can be expressed deeply. In this way, by making the total output power smaller than the foaming level Pw2 (second level), the dark portion does not foam. When it is desired to express the dark portion lightly, the output power PwA is set to the same value as the visual discrimination level Pw1 (first level), and the output powers PwB to PwD are set to be small so that the degree of change in print density. As shown in FIG. 10B, only a dark portion can be expressed lightly, and a thin portion can also be visually determined. In addition to the above settings, the output power PwA is not less than the visual discrimination level Pw1 (first level), and the sum of the output powers PwA to PwD may be set to be smaller than the foaming level Pw2 (second level).

  Thus, in the laser printing method of the present embodiment, the output powers PwA to PwD can be individually adjusted, so that the user can adjust the degree of change in print density.

4 Work Pa 'Print image Pb' Print image Pc 'Print image Pd' Print image

Claims (3)

  Using a plurality of different threshold values set for the density of the grayscale image, generating a plurality of binary images obtained by binarizing the grayscale image, sequentially selecting the generated binary images one by one, A laser printing method comprising irradiating a predetermined range of a workpiece with laser light based on the selected binary image.   Of the laser beams that are sequentially irradiated, the output of at least one laser beam is a first level or higher that can print a density that can be discriminated by human vision, and the total output of the laser beams that are sequentially irradiated is 2. The laser printing method according to claim 1, wherein the workpiece is smaller than a second level at which the workpiece is foamed. Threshold setting means for setting a plurality of different thresholds for the density of the grayscale image;
Binary image generation means for binarizing a grayscale image using a plurality of threshold values set by the threshold setting means and generating a plurality of binary images;
Laser printing, comprising: a plurality of generated binary images one by one sequentially, and laser light irradiation means for irradiating a predetermined range of the workpiece with laser light based on the selected binary images apparatus.