KR100823286B1 - Shingling printing method - Google Patents

Abstract

The disclosed shingling printing method comprises the steps of: conveying paper in a forward direction; A second step of conveying the paper in a reverse direction; Moving the inkjet head in the main scanning direction; And repeatedly performing and printing the series of processes. Unlike the conventional invention, the present invention can perform a shingling in the main scanning direction at the same time as the shingling in the paper feed direction to implement a high quality image.

Description

Shingling printing method

1 is a cross-sectional view schematically showing an embodiment of an inkjet image forming apparatus according to the present invention.

FIG. 2 is a diagram illustrating a configuration of the inkjet head and the transfer unit of FIG. 1.

3 is a view showing a nozzle portion of the inkjet head.

4 is a view showing the configuration of an inkjet image forming apparatus for shingling printing.

5 is a perspective view illustrating the eccentric cam of FIG. 4.

6 is a view for explaining a printing method according to an embodiment of the shingling printing method of the present invention.

FIG. 7 is a view illustrating a process of forming an image on a sheet during printing by the shingling printing method of FIG. 6.

8 is a view for explaining a printing method according to another embodiment of the shingling printing method of the present invention.

9 is a flow chart showing an algorithm of a shingling printing method according to a preferred embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

5 ....... inkjet head 10 ....... body

11 ...... Nozzle part 12, 13 ... Medium roller

15 ...... Feeding Roller 17 ....... Pickup Roller

M ....... Main Scan Direction S ........ Sub Scan Direction

30 ...... Paper transport 60 ....... Head feed

70 ...... Adjustment part 72 ....... Eccentric Cam

76 ...... Drive 80 ....... Control

90 ...... Bias section 91 ....... Elastic member

92 ... body frame

The present invention relates to an inkjet image forming apparatus, and more particularly, to an inkjet image forming apparatus of a line printing method having an inkjet head having a nozzle portion having a length corresponding to the width of a sheet.

In general, the inkjet image forming apparatus refers to an apparatus for forming an image by ejecting ink from an inkjet head reciprocated in a direction perpendicular to the conveyance direction of the sheet at a predetermined interval from the upper surface of the sheet. As such, an image forming apparatus for printing an image by injecting ink onto the sheet while being conveyed in a direction perpendicular to the conveying direction of the sheet is called a shuttle type inkjet image forming apparatus. The inkjet head of the shuttle-type inkjet image forming apparatus is provided with a nozzle portion having a plurality of nozzles for ejecting ink.

In recent years, attempts have been made to implement high-speed printing by using inkjet heads having nozzle portions having a length corresponding to the width of the paper instead of inkjet heads reciprocally transported in the width direction of the paper. The image forming apparatus operated in this manner is called a line printing inkjet image forming apparatus. In such a line printing type inkjet image forming apparatus, the inkjet head is fixed, and only paper is conveyed. Therefore, the driving device of the inkjet image forming apparatus is simple and high speed printing can be realized.

However, in the above-mentioned line printing inkjet image forming apparatus, when some of the nozzles are damaged and ink cannot be ejected, the printing is not performed on the part of the paper corresponding to the damaged nozzle, such as a white line. Defects appear. In order to prevent such a poor image quality, the shuttle type inkjet image forming apparatus prints using a shingling method. Here, the shingling method refers to a technique of repeatedly overlapping printing while moving a print position finely.

However, in the conventional line-printing inkjet image forming apparatus, ink is sprayed only once in the advancing direction of the paper, and it is not easy to print by the shingling method in order to solve the above problems due to its structural characteristics. In addition, in the line printing type inkjet image forming apparatus, the resolution of the printout is determined by the physical distance between the nozzles. However, in the conventional line printing type inkjet image forming apparatus, since the inkjet head is fixed, it cannot be output at a higher resolution than the actual resolution.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide an inkjet image forming apparatus of a line printing method capable of outputting a higher resolution than the actual resolution. Further, an object of the present invention is to provide an inkjet image forming apparatus of a line printing method which can prevent deterioration of image quality by multi-printing a damaged nozzle area when some of the nozzles are damaged and cannot eject ink. Another object of the present invention is to provide an inkjet image forming apparatus of a line printing method which can be printed using a shingling method.

The shingling printing method according to the present invention comprises: an inkjet head for printing an image by ejecting ink onto a paper by nozzles arranged in the main scanning direction, and using an inkjet image forming apparatus having a feeding roller and a delivery roller for transporting the paper. In shingling printing method,

A first step of printing the paper by transporting it in the forward direction; A second step of conveying the paper in a reverse direction; A third step of moving the inkjet head in the main scanning direction; And a fourth step of repeatedly performing the first step, the second step, and the third step n times and printing the same.

In one embodiment, the second step, it is preferable to transfer the paper less than or equal to the distance from the top end nozzle close to the feeding roller to the feeding roller.

In one embodiment, the distance that the paper is conveyed in the reverse direction is preferably smaller than the distance that the paper is conveyed in the forward direction.

In an embodiment, the third step may include moving the inkjet head in stages by a size equal to a physical distance between the nozzles for determining the resolution in the horizontal direction.

In an exemplary embodiment, the third step may include moving the inkjet head stepwise by a size obtained by dividing the physical distance between the nozzles for determining the resolution in the horizontal direction by a size obtained by multiplying the distance between the nozzles by an integer multiple. It is preferable to make it.

In an embodiment, the third step may include: when the resolution of the actual nozzle is l and the resolution to be printed is m, the inkjet head by the size equal to the physical distance between the nozzles equal to m / l in the horizontal direction. It is preferable to move step by step. Here, the nozzle is preferably formed longer than the width of the paper. In addition, the discharge roller is characterized in that it comprises a star wheel installed in the main scanning direction, and a support roller facing the support of the back of the paper.

An inkjet image forming apparatus according to the present invention comprises: an inkjet head which is installed to be reciprocated in a main scanning direction by printing ink by spraying ink onto a paper by a nozzle disposed in the main scanning direction; A paper conveying unit having a feeding roller and an ejecting roller for conveying the paper in a forward or reverse direction; A head transfer part which moves in the main scanning direction by interfering with the ink jet head; And a control unit for controlling the operation of the paper transfer unit and the head transfer unit.

The control unit controls the operation of the paper conveying unit to transfer the paper in the forward direction and to print the paper in the reverse direction, and controls the operation of the head conveying unit to move the inkjet head in the main scanning direction when conveying in the reverse direction. Characterized in that.

In one embodiment, the control unit, characterized in that for repeating the transfer of the paper in the reverse direction n times and printing on the paper.

In one embodiment, the control unit, it is preferable to convey the paper in the reverse direction less than or equal to the distance from the top end nozzle close to the feeding roller to the feeding roller.

In one embodiment, the control unit, it is preferable to convey the paper so that the distance that the paper is conveyed in the reverse direction is smaller than the distance that the paper is conveyed in the forward direction.

In one embodiment, the control unit, it is preferable to move the inkjet head in steps by a size equal to the physical distance between the nozzles for determining the resolution in the horizontal direction.

In an exemplary embodiment, the controller may move the inkjet head stepwise by a size obtained by dividing the physical distance between the nozzles for determining the resolution in the horizontal direction by a size obtained by multiplying the distance between the nozzles by an integer multiple. desirable.

In one embodiment, the control unit, when the resolution of the actual nozzle is l and the resolution to be printed to m, the inkjet head in stages by the size equal to the physical distance between the nozzles divided by m / l in the horizontal direction It is preferable to move.

In one embodiment, the head transfer unit, the control unit for moving the inkjet head in the main scanning direction step by step to interfere with the inkjet head; And a bias unit for biasing the inkjet head moved by the adjusting unit to its original position.

In one embodiment, the control unit, the eccentric cam rotatably installed on the main frame to interfere with the inkjet head; And a drive source for rotating the eccentric cam.

In an embodiment, the bias unit may include an elastic member installed between the main body frame and the inkjet head to elastically bias the inkjet head to its original position.

Here, the nozzle is preferably formed longer than the width of the paper. In addition, the discharge roller is characterized in that it comprises a star wheel installed in the main scanning direction, and a support roller facing the support of the back of the paper.

Hereinafter, a shingling printing method and a line printing type inkjet image forming apparatus according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. In this process, the thickness of the lines or the size of the components shown in the drawings are exaggerated for quick understanding of the description. Also, for convenience of description, an inkjet image forming apparatus having a line-printing inkjet head having a nozzle portion having a length corresponding to the width of a paper will first be described, followed by a shingling printing method.

1 is a cross-sectional view schematically showing an embodiment of an inkjet image forming apparatus according to the present invention, and FIG. 2 is a view showing a configuration of an inkjet head and a transfer unit of FIG. 1. 3 is a view showing the nozzle portion of the inkjet head, Figure 4 is a view showing the configuration of the inkjet image forming apparatus for shingling printing, Figure 5 is a perspective view showing the eccentric cam of FIG. 6 is a view for explaining a printing method according to an exemplary embodiment of the shingling printing method of the present invention, and FIG. 7 illustrates a process of forming an image on paper during printing by the shingling printing method of FIG. 6. 8 is a view for explaining a printing method according to another embodiment of the shingling printing method of the present invention.

Referring to FIG. 1, an inkjet image forming apparatus includes a paper feed cassette 20, a pickup roller 17, an inkjet head 5, a support member 14 positioned to face the sheet, and a paper P. FIG. A paper conveying section 30 for conveying in the sub-scanning direction S, and a stacking section 50 for stacking the paper P after discharge. In addition, the paper conveying unit 30 includes a feeding roller 15 and discharge rollers 12 and 13, and conveys the paper P along a predetermined path. Here, the main scanning direction M means the width direction of the paper P to be conveyed, and the sub scanning direction S means the conveying direction of the paper P.

The paper P is loaded in the paper feed cassette 20, and the paper P is conveyed in the sub-scanning direction S by the pickup roller 17 and the paper feeder 30. In addition, a pickup roller 17 is installed at one side of the paper feed cassette 20 to transfer the paper P loaded on the paper feed cassette 20 to the feeding roller 15. The pick-up roller 17 rotates the upper surface of the paper P in a pressurized state to transfer the paper P out of the paper cassette 20.

The paper feeder 30 is rotated forward and backward by a driving source (not shown) such as a motor, and transfers the paper P in the forward or reverse direction of the sub-scanning direction S. FIG. Here, the forward direction means the direction in which the paper P is picked up by the pickup roller 17 and conveyed to the inkjet head 5, and the reverse direction means the opposite direction.

The feeding roller 15 is installed at the mouth side of the inkjet head 5, and transfers the paper P drawn out from the paper feed cassette 20 to the inkjet head 5, or in the reverse direction for shingling printing. . In this case, the feeding roller 15 may perform a function of aligning the paper P so that ink may be sprayed onto a desired portion of the paper P before the paper P passes through the inkjet head 5. . The feeding roller 15 may be composed of a driving roller that provides a feed force for transferring the paper P, and an idle roller that is elastically engaged thereto. Between the pickup roller 17 and the feeding roller 15, a pair of feed rollers 16 for transferring the paper P may be further installed.

The discharge rollers 12 and 13 are installed at the exit side of the inkjet head 5 to discharge the printed paper P out of the image forming apparatus or to convey the paper P in the reverse direction for shingling printing. . As shown in FIGS. 1 and 2, the discharge rollers 12 and 13 have a star wheel 12 installed in the main scanning direction M, and a support roller facing the back surface of the paper P for supporting the back wheel of the paper P. 13). The paper P, into which ink is injected onto the upper surface while passing through the nozzle unit 11, may be wetted by the ink to generate waves. If the wave becomes severe, the paper P may come into contact with the bottom of the nozzle unit 11 or the body 10 to spread ink which has not been dried yet and contaminate the image. Moreover, the possibility that the space | interval of the paper P and the nozzle part 11 is not maintained is very high. The star wheel 12 may be formed by contacting the bottom surface of the nozzle unit 11 or the body 10 with the paper P transported below the nozzle unit 11 or changing the distance between the paper P and the nozzle unit 11. In order to prevent this, at least a part is provided to protrude more than the nozzle portion 11 and is in point contact with the upper surface of the paper (P). According to such a configuration, the star wheel 12 can be prevented from being contaminated by the top surface of the paper P by being sprayed on the top surface of the paper P to contaminate the ink image that is not yet dry. In addition, a plurality of star wheels may be installed to smoothly transport the paper P. When a plurality of star wheels are installed side by side in the sub-scanning direction S, it is preferable that a plurality of support rollers corresponding to each star wheel is further provided.

The support member 14 supports the back surface of the paper P, which is provided below the ink jet head 5 and conveyed so that the nozzle unit 11 and the paper P maintain a predetermined interval. The distance between the nozzle part 11 and the paper P is about 0.5-2.5 mm.

2 and 3, the inkjet head 5 prints an image by ejecting ink onto the paper P by nozzles 11C, 11M, 11Y, and 11K arranged in the main scanning direction M, It is installed to reciprocate in the main scanning direction (M). In one embodiment, the inkjet head 5 may be coupled to a guide member (not shown) installed in parallel to the nozzle unit 11 on the main body frame and reciprocated in the main scanning direction M. FIG. Since such a coupling method is well known to those skilled in the art of inkjet head, a detailed description thereof will be omitted. However, the inkjet head 5 of the present invention is not a shuttle type inkjet head for printing an image by injecting ink onto the paper while being transported in a direction perpendicular to the conveying direction of the paper, but having a nozzle portion having a length corresponding to the width of the paper. And a line printing type inkjet head for printing an image by ejecting ink at a fixed position. However, the present invention uses an inkjet head of a line printing method, but is installed to be movable in the main scanning direction M for shingling printing.

The inkjet head 5 includes a body 10 and a nozzle portion 11 provided on the bottom surface of the body 10. The feeding roller 15 is installed at the inlet side of the nozzle unit 11 and the star wheel 12 is installed at the outlet side. Referring to FIG. 3, a plurality of nozzles 11C, 11M, 11Y, and 11K for ejecting ink are arranged in the main scanning direction M in the nozzle unit 11. The nozzle unit 11 may be provided with four nozzle arrays for injecting ink of, for example, cyan (C), magenta (M), yellow (Y), and black (K) colors for color printing. Can be. The nozzles 11C, 11M, 11Y, and 11K, that is, four nozzle rows, are preferably formed longer than the width of the paper P. The body 10 contains ink. Although not shown in the drawings for accommodating cyan (C), magenta (M), yellow (Y), and black (K) colors, the body 10 may be divided into four storage spaces. In addition, although not shown in the drawings, the body 10 includes a chamber provided with injection means (for example, a piezo element and a heater) that communicate with the respective nozzles of the nozzle unit 11 and provide a pressure for jetting ink. A flow path for supplying ink contained in the body 10 to the chamber is further provided. Chambers, injection means, flow paths and the like are well known to those skilled in the art of inkjet heads, so a detailed description thereof will be omitted. For convenience of explanation, the nozzle unit 11 will be described by taking an example in which the nozzles 11 are arranged in the order of cyan (C), magenta (M), yellow (Y), and black (K). In the present exemplary embodiment, the nozzle unit 11 of the color inkjet method has been described as an example, but the nozzle unit 11 may have various forms in addition to the above, and the technical scope of the present invention is not limited to those illustrated in FIG. 3.

4 and 5, the head transfer unit 60 moves in the main scanning direction M by interfering with the ink jet head 5. That is, the head transfer unit 60 moves in the main scanning direction M step by step while interfering with the inkjet head 5 during printing by the shingling printing method described later in order to increase the resolution. The head transfer unit 60 includes an adjustment unit 70 and a bias unit 90.

The adjusting unit 70 moves the ink jet head 5 stepwise in the main scanning direction M by interfering with the ink jet head 5. In one embodiment, the adjusting unit 70 is provided to be rotatable in the main body frame (not shown) and includes an eccentric cam 72 that interferes with the inkjet head 5, and a driving source 76 for rotating the eccentric cam. . The eccentric cam 72 is composed of a rotating portion 74 rotatably inserted into the main body frame, and an interference portion 73 that interferes with the inkjet head 5. Rotating portion 74 is inserted into the coupling hole (not shown) provided in the main body frame is rotatably installed around one point (75). Rotating portion 74 is preferably composed of a gear member so as to receive a rotational force from the drive source 76 to be described later. In addition, the interference portion 73 is formed to be eccentric with respect to the rotation portion 74 so that the ink jet head 5 can be moved in the main scanning direction M by interfering with the ink jet head 5 when the rotation portion 74 is rotated. It is preferable. Unlike shown, the interference part 73 may be manufactured in an elliptical shape. The drive source 76 provides a driving force for rotating the eccentric cam 72. As the drive source 76, a piezoelectric element or the like which is mainly used in an apparatus requiring precise position control may be used. Piezoelectric elements are widely known in the art to which the present invention pertains, and thus detailed description thereof will be omitted.

The bias unit 90 biases the inkjet head 5 moved by the adjusting unit 70 to its original position. That is, the bias unit 90 elastically biases the inkjet head 5 in the direction of contact with the adjusting unit 70 during printing by the shingling printing method described below. In one embodiment, the bias unit 90 preferably includes an elastic member 91 provided between the main frame 92 and the inkjet head 5 to elastically bias the inkjet head 5 to its original position. . As described above, the inkjet head 5 is reciprocated by the adjusting unit 70 and the bias unit 90.

Referring to FIG. 4, the controller 80 controls the operations of the paper transfer unit 30 and the head transfer unit 60 so that the inkjet image forming apparatus can print by shingling printing. The shingling printing method according to the present invention is to finely move the printing position of the inkjet head 5 in the main scanning direction (M) while dividing and repeatedly printing an image corresponding to one pixel at several times to form a high quality image. Means the way. In the present embodiment, the control unit 80 controls the operation of the paper conveying unit 30 to convey the paper P in the forward direction, and then to the reverse direction after printing, and to move the ink jet head 5 in the reverse direction. The operation of the head transfer unit 60 is controlled to transfer in the main scanning direction M. In one embodiment, the control unit 80 repeats the transfer of the paper (P) in the reverse direction n times and prints on the paper (P). Here, n means the number of times the paper (P) is conveyed in the reverse direction.

When printing by shingling printing method, if the feed amount in the reverse direction is larger than the distance from the topmost nozzle 11C close to the feeding roller 15 to the feeding roller 15, it is sprayed on the upper surface of the paper P and is still The ink image, which is not dry, may be contaminated as it is drawn between the feeding rollers 15. Therefore, the control unit 80 reversely moves the paper P in a reverse direction so as to be smaller than or equal to a distance (D: see FIG. 2) from the nozzle 11C at the uppermost end close to the feeding roller 15 to the feeding roller 15. It is preferable to transfer.

As an exemplary embodiment, as shown in FIG. 6, the controller 80 has a distance D _b at which the paper P is conveyed in a reverse direction than a distance D _{f at} which the paper P is conveyed in the forward direction. It is preferable to convey the paper P so that it is. Here, the distance D _b at which the paper P is conveyed in the reverse direction should be smaller than or equal to the distance D (see FIG. 2) from the nozzle 11C at the uppermost end to the feeding roller 15.

In addition, in order to print by the shingling printing method, it is preferable that the control unit 80 moves the physical distance (d: see FIG. 3) between the nozzles, which is a factor for determining the resolution, stepwise by an equal amount in the horizontal direction. . That is, it is preferable that the controller 80 controls the operation of the head conveyer 60 to move the inkjet head 5 by the size equal to the above in the horizontal direction whenever the paper P is conveyed in the reverse direction. . However, since the size of dividing the physical distance d between the nozzles in the horizontal direction is very small, it is not easy to move the inkjet head 5 as described above. Therefore, the controller 80 may move the inkjet head 5 step by step by the size obtained by multiplying the physical distance d between the nozzles by the integral multiple as described above. As an example, when the physical distance between the nozzles is d and the number of times the paper P is conveyed in the reverse direction is n, the inkjet head 5 is d / (n + 1) every time the paper P is conveyed in the reverse direction. It is preferable to convey the size or size by multiplying the physical distance d between the nozzles by an integer multiple.

As an embodiment, when the actual resolution of the nozzle unit is l and the resolution to be printed is m, the control unit 80 gradually divides the physical distance d between the nozzles by the size equal to m / l in the horizontal direction. It is preferable to move the inkjet head 5 with the. Therefore, the number n of sheets P to be conveyed in the reverse direction may satisfy the relationship of n = m / l −1. At this time, it is preferable that the number n of the papers P being conveyed in the reverse direction is controlled to satisfy the relationship of D _b / D _f = n / (n + 1).

Hereinafter, for quick understanding of the description, the inkjet head 5 having a distance D from the topmost nozzle 11C to the feeding roller 15 is 30 mm and the resolution l of the actual nozzle is 300 dpi is used. The case where the resolution m of 1200 dpi is to be outputted is described as an example. Here, since the distance D _{b at} which the paper P is conveyed in the reverse direction should be smaller than or equal to the distance D from the nozzle 11C at the uppermost end to the feeding roller 15, it is assumed that D _b = D. The number n of sheets P being conveyed in the reverse direction is n = 1200 (m) / 300 (l)-1, so n = 3. At this time, the distance D _{f in} which the paper P is conveyed in the forward direction should satisfy the relationship D _b / D _f = n / (n + 1), so D _f is 40 mm. That is, in order to output a resolution of 1200 dpi using the inkjet head 5 having 300 dpi, the paper P must be transported at least three times in the reverse direction when printing by the shingling printing method. That is, it is necessary to spray ink four times on the paper P to realize a resolution of 1200 dpi.

The shingling printing process as described above will be described in detail with reference to the accompanying drawings. Reference numbers P ₁ , P ₂ , P ₃ , and P ₄ refer to the paper being conveyed in the forward direction, D _f is the distance the paper P is fed in the forward direction, and D _b is the distance the paper is fed in the reverse direction. do. In addition, D ₁ , D ₂ , D ₃ , and D ₄ mean one pixel. For quick understanding of the description, the pixels are exaggerated than the actual size in FIGS. 6 and 7.

6 and 7, the ink is ejected only to a region corresponding to a resolution of 300 dpi by the ink ejected from the inkjet head 5 while the paper P ₁ is transported by D _f in the forward direction during initial printing. An image is formed. Then, the sheet of paper P ₁ is conveyed by the sheet conveying unit 30 by D _b in the reverse direction. At this time, the inkjet head 5 is moved by the head transfer part 60 in the main scanning direction M by a predetermined distance. That is, the inkjet head 5 is moved to a position where ink can be injected into the region c shown in FIG. In the second printing, the paper P ₂ is conveyed by D _f in the forward direction, and ink is ejected to a region corresponding to a resolution of 300 dpi by the ink ejected from the inkjet head 5 to form an image. Repeating the above process, the ink is ejected to the e region of the paper P ₃ during the third printing, and the image is formed, and the ink is ejected to the g region of the paper P ₄ during the fourth printing, and the image is formed. . That is, an image corresponding to 1200 dpi is printed on the paper through three reverse feeds D _b and four forward feeds D _{f as} described above. In the present exemplary embodiment, the printing is performed in the order of the a region, the c region, the e region, and the g region. For example, it may be printed in the order of a region, e region, c region, and g region.

In another embodiment, in FIG. 8, the paper is repeatedly printed four times while feeding the paper by the same distance in the forward and reverse directions, and then doubled the paper in the forward direction (2 * D _f ) during the fourth printing. A method of repeating printing four times is shown. By repeating this process, an image corresponding to 1200 dpi can be printed on the paper.

Hereinafter, a shingling printing method according to a preferred embodiment of the present invention will be described.

9 is a flow chart showing an algorithm of a shingling printing method according to a preferred embodiment of the present invention.

2 and 9, when printing starts (step 100), the control unit 80 (see FIG. 4) determines whether or not to print using the shingling printing method (step 102). The operation of the transfer unit 60 is controlled. When printing in the normal mode, the paper (P) is transported in the forward direction to print (step 120). When printing is finished, the paper P is transferred out of the image forming apparatus by the discharge rollers 12 and 13 (step 130).

When printing by the shingling printing method, the paper P is conveyed in the forward direction to perform a printing operation (step 104).

Then, the paper P is conveyed in the reverse direction (step 106). When conveying the paper P in the reverse direction, it is preferable to transport the paper P to be smaller than or equal to the distance D from the topmost nozzle 11C close to the feeding roller 15 to the feeding roller 15. . In addition, it is preferable that the distance that the paper P is conveyed in the reverse direction is smaller than or equal to the distance that the paper P is conveyed in the forward direction.

When the paper P is conveyed in the reverse direction as described above, the inkjet head 5 is moved in the main scanning direction M by the head conveying unit 60 (step 108). The step (106) of transferring the paper P in the reverse direction and the step (108) of moving the inkjet head 5 may be performed simultaneously, or one step may be performed before the other step. At this time, the inkjet head 5 is moved in steps by the size equal to the physical distance between the nozzles (d: see FIG. 3) in the horizontal direction, or the integer multiple of the physical distance (d) between the nozzles to the equal size as described above. Preferably, the multiplied size is moved in steps by the size. Alternatively, when the resolution of the actual nozzle is l and the resolution to be printed is m, the inkjet head 5 may be moved by the size equal to the physical distance d between the nozzles equal to m / l in the horizontal direction.

When the paper P is conveyed in the reverse direction as described above, the paper P is transferred again in the forward direction to perform a printing operation (step 110). The above process is repeated until the desired image is printed (step 112). When printing is finished, the paper P is transferred out of the image forming apparatus by the discharge rollers 12 and 13 (step 130).

As described above, the shingling printing method and the inkjet image forming apparatus according to the present invention can implement a high-quality image by performing the shingling in the main scanning direction and the shingling in the paper feed direction as well as the conventional invention. . In addition, the resolution of the inkjet head is physically determined by the distance between the nozzles, and the present invention can output the printed matter at a higher resolution than the actual resolution by using the shingling printing method. In addition, even when some of the nozzles provided in the inkjet head are damaged, the image can be reduced by moving the inkjet head in the main scanning direction to reduce the quality deterioration caused by the damaged nozzle. In addition, the present invention can improve the print quality by multi-printing by printing the color first at a low resolution and then filling the image again after a predetermined time has elapsed.

Although the present invention has been described with reference to the embodiments shown in the drawings, this is merely exemplary, and those skilled in the art to which the art belongs can make various modifications and other equivalent embodiments therefrom. Will understand. Therefore, the true technical protection scope of the present invention will be defined by the claims below.

Claims (21)

A shingling printing method using an inkjet image forming apparatus having an inkjet head for printing an image by line printing by spraying ink onto a paper by a plurality of nozzles arranged in the main scanning direction, and a feeding roller and a discharge roller for conveying the paper. To Transferring the paper in a forward direction and printing an image at a resolution l of the inkjet head; Conveying the paper in a reverse direction; Moving the inkjet head in the main scanning direction corresponding to the resolution m to be printed; And Repeating the above steps and printing; The shingling printing method characterized in that the conveying distance in the reverse direction is smaller than the conveying distance in the forward direction. A shingling printing method using an inkjet image forming apparatus having an inkjet head for printing an image by line printing by spraying ink onto a paper by a plurality of nozzles arranged in the main scanning direction, and a feeding roller and a discharge roller for conveying the paper. To Transferring the paper in a forward direction and printing an image at a resolution l of the inkjet head; Moving the inkjet head in the main scanning direction corresponding to m for resolution to be printed; Conveying the paper in a reverse direction; And Repeating the above steps and printing; The shingling printing method characterized in that the conveying distance in the reverse direction is smaller than the conveying distance in the forward direction. The method according to claim 1 or 2, A shingling printing method, characterized in that for conveying the paper in a reverse direction less than or equal to the distance from the feeder nozzle closest to the feeding roller to the feeding roller. delete The method of claim 3, wherein the moving of the ink jet head in the main scanning direction comprises: The shingling printing method according to claim 1, wherein the inkjet head is moved in steps of the physical distance between the nozzles for determining the resolution l by the size equal to m / l in the main scanning direction. The method of claim 3, wherein the moving of the ink jet head in the main scanning direction comprises: Characterized in that the inkjet head is moved in steps by a size obtained by dividing the physical distance between the nozzles determining the resolution l by m / l in the main scanning direction, and multiplying the distance between the nozzles by an integer multiple. How to print shingling. delete The method of claim 3, The nozzle printing method, characterized in that the nozzle is formed longer than the width of the paper. The method of claim 3, The discharge roller is shingling printing method characterized in that it comprises a star wheel installed in the main scanning direction and a support roller facing the paper support to support the back of the paper. delete delete delete delete delete delete delete delete delete delete delete The method according to claim 1 or 2, When the number of times the paper is conveyed in the reverse direction is N, N = (m / l) -1 characterized in that shingling printing method.

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