JP4108026B2 - Building board printer - Google Patents

Description

  The present invention relates to a building board printing apparatus using ink jet printing technology, and more particularly to a building board printing apparatus capable of expressing a wide gradation.

  In a conventional inkjet printing apparatus, a small-diameter nozzle and a large-diameter nozzle are provided, and a small-diameter nozzle is used for normal high-definition printing. A large-diameter nozzle is used when high-definition printing is not required. Has been proposed (see, for example, Patent Document 1).

JP 2000-6442 A

  However, in the conventional ink jet printing apparatus, the nozzle arrangement pitch is the same, for example, the nozzle arrangement pitch is the same for both nozzles, so that the density is sufficiently high to very low. There is a problem that gradation expression over a wide range of colors cannot be performed.

  In view of the above problems, an object of the present invention is to provide a building board printing apparatus capable of expressing gradations over a wide range from a high density to a low density by devising the aperture and arrangement of the inkjet nozzles.

The building board printing apparatus according to the present invention includes a first nozzle array in which a plurality of inkjet nozzles having a first diameter are fixedly arranged in a lateral direction (a direction orthogonal to a traveling direction of the building board) at a first pitch. a plurality of ink jet nozzles the longitudinal direction (the direction perpendicular to the horizontal direction, i.e., building board traveling direction) to the first pitch by being staggered in a zigzag shape having a larger second diameter than the first bore in the second pitch of half being disposed laterally to the first nozzle array and the longitudinal be fixedly disposed at predetermined intervals, two second nozzles which eject a first nozzle array and the same color of ink And the inkjet nozzles of the two second nozzle arrays eject ink simultaneously .

  In addition, the first nozzle array includes a plurality of nozzle arrays in which the respective inkjet nozzles are arranged at the same position in the horizontal direction, so that many gradations can be expressed by the plurality of nozzle arrays.

According to the present invention, gradation expression over a wide range of density can be achieved in an ink jet type construction board printing apparatus. In addition, since a region having a high print density where nozzle clogging is likely to occur is printed with a large-diameter nozzle, the occurrence of nozzle clogging can be reduced. Furthermore, since the second nozzle array has two inkjet nozzles arranged in a staggered pattern in the vertical direction and ejects ink at the same time, it is possible to perform almost solid high density printing without streaking. In addition, an unnatural line does not occur at the boundary between the printing areas formed by the large-diameter nozzle array and the small-diameter nozzle array.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a diagram illustrating an arrangement example of a print head of a building board printing apparatus according to an embodiment of the present invention. The printing surface, which is the design surface of the building board, has been subjected to printing ground treatment in advance. As the printing ground treatment, for example, a cement sealer treatment is performed with a color sealer. In this case, the background color is, for example, white or light, and is determined in consideration of the printed image tone (color mixing effect). While the building board is conveyed in the direction of travel of the building board, the black normal density correspondence head HK1 and the high density correspondence head HK2, the cyan normal density correspondence head HC1 and the high density correspondence head HC2, and the magenta color normal A density corresponding head HM1 and a high density corresponding head HM2, a yellow normal density corresponding head HY1, and a high density corresponding head HY2 are provided. Each of the print heads HK1, HK2, HC1, HC2, HM1, HM2, HY1, and HY2 is a fixed head and has a head separation method for each color.

  FIG. 2 is a diagram illustrating an example of the nozzle arrangement on the lower surface of the print head. Here, the case of the black normal density correspondence head HK1 and the high density correspondence head HK2 will be described as an example. The same applies to other colors. First, the normal density correspondence head HK1 has a nozzle pitch p (= V / f, V = building board conveyance speed) in a straight line in the horizontal direction (direction orthogonal to the building board traveling direction) of the inkjet nozzle having an opening area S1. Three rows of nozzle arrays arranged at intervals of f = ink ejection frequency are further arranged at intervals of the nozzle pitch p in the vertical direction (building plate traveling direction).

  The high density compatible head HK2 is a nozzle array in which inkjet nozzles having an opening area S2 (S2> 3 × S1) are arranged in two rows in the horizontal direction and staggered in the vertical direction at intervals of the nozzle pitch p / 2. Is placed. The nozzle pitch in the horizontal direction of each row is p. In the case of high-density image formation, this nozzle arrangement is based on the fact that the dot density per unit area is high, the blank area is extremely small, and the print state is substantially solid. It is an array for realizing the printing state.

  Further, the distance between the nozzle center of the third row of the normal density support head HK1 and the nozzle center of the first row of the high density support head HK2 is set to q (> p) in terms of housing design.

  FIG. 3 is a diagram showing a comparison of the size of the printed dots to be formed. When one drop of ink is printed using the normal density compatible head HK1, the print dot diameter is a1, and the print dot area is S1. The print dot area S1 is not necessarily the same as the inkjet nozzle opening area S1, but is approximately the same size. Similarly, in the case of two ink drops, the print dot diameter is a2, and in the case of three ink drops, the print dot diameter is a3. When the high density head HK2 is used, the print dot diameter is b, and the print dot area is S2. The print dot area S2 is not necessarily the same as the inkjet nozzle opening area S2, but is approximately the same size.

  FIG. 4 is a diagram illustrating a relative arrangement relationship of the printed dots to be formed. The printing dots by the high density corresponding head HK2 are circles having a diameter of about p, and the adjacent printing dots are almost fused at the ends (the hatched portions in the figure). This leads to a phenomenon that the number of blank areas (non-printing areas) is extremely small because the pixel configuration of the high-density image has a high density arrangement.

  On the other hand, the adjacent print dots by the normal density corresponding head HK1 are separated from each other, and the influence of the background color is inevitable.

  FIG. 5 is a diagram showing a procedure for creating print control data. All the actual work is done using the display screen of the image processing computer.

  First, the printed surface of the building board and the printed image reproduced there are displayed on a display screen in a reduced scale (FIG. 5 (a)).

  For the printing surface and print image displayed on the screen, RGB (Red Green Blue) → CMYK (Cyan Magenta Yellow Black) data conversion is performed, and data correction is performed based on the characteristics of the ink used to obtain CMYK data. Further, this is converted into halftone dots by a dot generator. Thus, the area is divided into two areas, a high density area and a medium to low density area, according to a predetermined threshold value set based on the number of halftone dots obtained. Based on the obtained position data for each color of CMYK for the high density area (FIG. 5B), it is converted to on / off data for the nozzles at the corresponding positions to obtain print control data (4).

  Further, for the medium to low density region, the obtained position data for each color of CMYK (FIG. 5 (c)) is classified into three levels of density based on the number of halftone dots, and the obtained classified position data (FIG. 5). Based on (d), FIG. 5 (e), and FIG. 5 (f)), the print control data (1), (2), and (3) are converted into on / off data for the nozzles at the corresponding positions. .

  Accordingly, the dark color print control data (1), the medium color print control data (2), the light color print control data (3) by the normal density compatible head HK1, and the high density print by the high density compatible head HK2. Control data (4) is acquired.

  FIG. 6 is a diagram for explaining the printing operation. As shown in FIG. 6A, in order to form printed dots having the size shown in the drawing in the rectangular areas to be printed A1 to E1 arranged in parallel in the horizontal direction and the rectangular areas to be printed X1 adjacent in the vertical direction, The execution timing of the assigned nozzle is controlled as shown in FIG.

  For the printing rectangular area A1, the nozzles in the first row are turned on at time t = 1. At this time, the front end line of the printed surface of the building board has reached the position y1. Further, the nozzles in the second row are turned on at time t = 3. At this time, the leading end line of the printed surface of the building board has reached the position y2. Further, the front end line of the next sequential area A2 in the vertical direction has reached the position y1, and control for forming a print dot for the next area A2 is started. Further, at time t = 5, the nozzles in the third row are turned on. At this time, the front end line of the printing surface of the building board has reached the position y3. As a result, high-density color dots (both hatched circles) are printed. The tip line of the next order area A2 has reached the position y2, and the tip line of the next order area A3 has reached the position y1. Then, control for forming a print dot for the area A3 is started.

  Similarly, for the region B1, the nozzles in the first row are turned on at time t = 3, and the nozzles in the second row are turned on at time t = 5. As a result, color dots in density (circles with diagonal lines) are printed. For region C1, the nozzles in the first row are turned on at time t = 5. As a result, low-density color dots (white circles) are printed. The same control is repeated for the subsequent areas B2, B3,..., C2, C3,.

  For the regions D1, E1, and X1, the nozzles in the first and second rows are simultaneously turned on at time t = 11 when Δt 2 + Δt 1 (= q / V + p / V) has elapsed from time t = 5. At this time, the leading end line of the printed surface of the building board has reached the position y6. Thereafter, printing dots are formed in the high density region in units of two columns at a cycle of 2 × Δt1.

  The present invention is not limited to the above embodiment. For example, it is of course possible to use only one of the first to third columns in the normal density compatible head. In this case, it goes without saying that the control can be performed very easily.

It is a figure which shows the example of arrangement | positioning of the print head of the building board printing apparatus by one embodiment of this invention. It is a figure which shows the example of nozzle arrangement | sequence of a print head lower surface. It is a figure which shows the comparison of the magnitude | size of the printing dot formed. It is a figure which shows the relative arrangement | positioning relationship of the printing dot formed. It is a figure which shows the preparation point of printing control data. It is a figure explaining printing operation.

Explanation of symbols

A1-X1 Rectangular area to be printed HK1, HC1, HM1, HY1 Normal density print head HK2, HC2, HM2, HY2 High density print head

Claims (2)

A first nozzle array in which a plurality of inkjet nozzles having a first diameter are fixedly arranged in a lateral direction (a direction perpendicular to a traveling direction of a building board) at a first pitch;
A plurality of inkjet nozzles having a second diameter larger than the first diameter are arranged in a staggered manner in the vertical direction (the direction orthogonal to the horizontal direction, that is, the traveling direction of the building board), thereby half the first pitch . second it has been arranged laterally at a pitch in the first nozzle array and the longitudinal be fixedly disposed at predetermined intervals, two of the second nozzle array for ejecting a first nozzle array and the same color of ink And the inkjet nozzles of the two second nozzle arrays discharge ink simultaneously .   2. The building board printing apparatus according to claim 1, wherein the first nozzle array includes a plurality of nozzle arrays in which the respective inkjet nozzles are arranged at the same position in the horizontal direction.

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