JP7183882B2 - LIQUID EJECTING APPARATUS AND LIQUID EJECTING METHOD - Google Patents

Description

The present invention relates to a liquid ejecting apparatus and a liquid ejecting method.

2. Description of the Related Art Conventionally, a liquid ejecting apparatus that ejects liquid onto a medium is known. As a typical example of a liquid ejecting apparatus, there is known an inkjet recording apparatus equipped with an inkjet head that ejects liquid ink onto a sheet-like medium to record an image. Ink jet recording apparatuses are also known that record images on both sides of a sheet.

When images are recorded on both sides of a sheet, the sheet expands and contracts due to the ink used to record the image on the front side, and the image on the back side is printed at a position shifted from the desired position. As a countermeasure against misalignment when printing an image on a sheet, there is known a technique of reading a test pattern printed on the sheet and generating correction data for each nozzle row of an inkjet head (see, for example, Patent Document 1). ).

However, the technique described in Patent Document 1 generates correction data prior to recording an image, so it is not possible to correct misalignment on the back side of the sheet in accordance with the image recorded on the front side of the sheet. Further, the technique described in Patent Document 1 applies one correction data to the entire sheet, so it cannot deal with local expansion and contraction of the sheet.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a liquid ejection device capable of adjusting the landing position of liquid on the back surface in more detail with respect to the liquid that has landed on the front surface.

In order to solve the above technical problem, one aspect of the present invention is a liquid ejecting apparatus that ejects liquid onto a front surface and a back surface of a medium to be ejected, comprising: a storage unit that stores a target position on the medium to be ejected; a first ejection unit for ejecting a non-transparent liquid that reflects or absorbs visible light onto the surface of the ejection receiving medium; and the surface read from the storage unit for dividing the ejection receiving medium into a plurality of small regions a transparent liquid ejecting section for ejecting a transparent liquid that transmits visible light to the target position of the target position; for each of the small regions on the back surface corresponding to the plurality of small regions, based on the difference between the target position read from the storage unit and the actual position read by the reading unit. a computing unit for individually computing landing positions of the non-transparent liquid; and a discharge part.

According to the present invention, the landing position of the liquid on the back surface can be adjusted in more detail with respect to the liquid that has landed on the front surface.

FIG. 2 is a hardware configuration diagram of an inkjet printer according to the embodiment; FIG. 2 is a schematic diagram showing the internal structure of an inkjet printer; Conceptual diagram showing the position of the transparency plot before and after inversion. The figure which shows the example of arrangement|positioning of a 1st target position. The figure which shows the example of arrangement|positioning of a 2nd target position. 4 is a flowchart of double-sided printing processing; 4 is a flowchart of image deformation processing; The figure which shows the state which recorded the image and transparency plot on the surface. FIG. 4 is a conceptual diagram showing the relationship between the target position and the actual position of the transparency plot;

[Embodiment of the present invention]
An inkjet printer 100 according to the present embodiment will be described below with reference to FIGS. 1 and 2. FIG. FIG. 1 is a hardware configuration diagram of an inkjet printer 100. As shown in FIG. FIG. 2 is a schematic diagram showing the internal structure of the inkjet printer 100. As shown in FIG.

As shown in FIG. 1, the inkjet printer 100 includes a CPU (Central Processing Unit) 110, a RAM (Random Access Memory) 120, a ROM (Read Only Memory) 130, a HDD (Hard Disk Drive) 140, an operation panel 150, and an I /F 160 are connected via a common bus 180 .

The CPU 110 is a computing means (computing section) and a controller that controls the operation of the entire inkjet printer 100 . The RAM 120 is a volatile storage medium from which information can be read and written at high speed, and is used as a working area when the CPU 110 processes information. The ROM 130 is a read-only non-volatile storage medium and stores programs such as firmware. The HDD 140 is a non-volatile storage medium capable of reading and writing information and having a large storage capacity, and stores an OS (Operating System), various control programs, application programs, and the like.

The inkjet printer 100 processes a control program stored in the ROM 130 , an information processing program (application program) loaded into the RAM 120 from a storage medium such as the HDD 140 , and the like using the computing function of the CPU 110 . A software control unit including various functional modules of the inkjet printer 100 is configured by the processing. A combination of the software control section configured in this way and the hardware resources installed in the inkjet printer 100 configures functional blocks that implement the functions of the inkjet printer 100 .

The operation panel 150 is a user interface including a display for displaying a screen, a touch panel superimposed on the display, push buttons, and the like. The touch panel and push buttons accept operator's operations for inputting various types of information, which will be described later. The I/F 160 includes a transport section 210 , a front surface recording section (first ejection section) 220 , a back surface recording section (second ejection section) 230 , a plot recording head (transparent liquid ejection section) 240 , and a reading section 250 . , and the drying section 260 to the common bus 180 .

As shown in FIG. 2, the inkjet printer 100 causes the conveying unit 210 to convey the continuous sheet S along the conveying path P, and ink ( This is an example of a liquid ejecting apparatus that records an image on a continuous sheet S by ejecting a liquid. However, a specific example of the liquid ejection device is not limited to the inkjet printer 100 . That is, the liquid ejecting apparatus is not limited to an apparatus that records an image on an ejection receiving medium, and may be an apparatus that applies a treatment liquid.

The continuous sheet S is an example of a medium to be ejected that is transported by the transport unit 210 . The continuous sheet S is a long strip of paper, and is cut into a predetermined length after ink is ejected from each of the heads 220-240. However, a specific example of the medium to be ejected is not limited to the continuous form sheet S, and may be, for example, cut paper cut into a predetermined size (for example, A4, B5, etc.). A typical example of the ejection receiving medium is paper or cloth woven with fibers that expand and contract when the absorbed ink dries.

The transport path P passes through the internal space of the inkjet printer 100 through which the continuous sheet S can pass, facing the heads 220 to 240, as indicated by the dashed lines in FIG. More specifically, the transport path P refers to the space between each head 220 to 240 and guide rollers 213, 214 and 215, which will be described later. In addition, although the straight transport path P is shown in FIG. 1, the shape of the transport path P is not limited to this, and may be partially curved, for example.

The conveying unit 210 includes, for example, conveying rollers 211 and 212 that convey the continuous sheet S in the conveying direction (leftward direction in FIG. 2). The transport roller 211 is arranged on the upstream side of the transport path P from the heads 220-240. The conveying roller 211 is rotated by the driving force of the conveying motor, and feeds the pre-wound continuous sheet S to the conveying path P. As shown in FIG. The transport roller 212 is arranged on the downstream side of the transport path P from the heads 220-240. The conveying roller 212 is rotated by the driving force of the conveying motor, and winds up the continuous sheet S on which ink has been ejected from the heads 220 to 240 .

Further, the transport section 210 includes guide rollers 213 , 214 and 215 arranged between the transport rollers 211 and 212 . The guide rollers 213 to 215 are arranged on the side opposite to the heads 220 to 240 with the transport path P interposed therebetween. The guide rollers 213 to 215 are idle rollers that are brought into contact with the continuous sheet S conveyed on the conveying path P and rotated by the movement of the conveyed continuous sheet S. As shown in FIG.

Further, the transport section 210 includes a reversing mechanism 216 that reverses the continuous sheet S. As shown in FIG. 3A and 3B are top views of the continuous sheet S before and after the reversing mechanism 216. FIG. As shown in FIG. 3, when the continuous sheet S passes through the reversing mechanism 216, it rotates around an imaginary line extending in the conveying direction and is turned upside down. The reversing mechanism 216 can be realized with a known configuration including various rollers. Hereinafter, the upper surface of the continuous sheet S before passing through the reversing mechanism 216 is referred to as "front side", and the upper surface of the continuous sheet S after passing through the reversing mechanism 216 is referred to as "back side".

The surface recording unit 220 records an image on the surface of the continuous sheet S by ejecting colored ink toward the surface of the continuous sheet S transported on the transport path P. FIG. The surface recording unit 220 includes a plurality of recording heads 221, 222, 223, and 224 that eject inks of different colors. In this embodiment, the print head 221 ejects black (Bk) ink, the print head 222 ejects cyan (C) ink, the print head 223 ejects magenta (M) ink, and the print head 224 ejects yellow (Y) ink. . However, the number and combination of colors ejected by the surface recording portion 220 are not limited to the above example.

The recording heads 221 to 224 are, for example, full-line type recording heads in which ink ejection holes are provided throughout the width direction of the continuous sheet S that intersects (perpendicularly) with the conveying direction. However, specific examples of the recording heads 221 to 224 are not limited to this, and for example, they may be of a carriage type in which a carriage having ink ejection holes formed therein ejects ink while moving in the width direction (main scanning direction). Further, the specific principle by which the recording heads 221 to 224 eject ink is not particularly limited. For example, ink may be ejected from the nozzles by vibrating piezoelectric elements due to drive voltage applied from the CPU 110 .

The back surface recording unit 230 records an image on the back surface of the continuous sheet S by ejecting colored ink toward the back surface of the continuous sheet S transported on the transport path P. FIG. The back surface recording unit 230 includes a plurality of recording heads 231, 232, 233, and 234, each of which ejects ink of a different color. The specific structure of the recording heads 231 to 234 and the color of the ink to be ejected are common to those of the recording heads 221 to 224, and thus the description thereof will be omitted.

The plot recording head 240 records a transparent plot on the surface of the continuous form sheet S by ejecting transparent ink toward the surface of the continuous form sheet S conveyed on the conveying path P. FIG. The specific structure of plot recording head 240 may be common to recording heads 221-224 and 231-234. On the other hand, the plot recording head 240 differs from the recording heads 221 to 224 and 231 to 234, which eject colored ink, in that it ejects transparent ink.

Here, colored ink is an example of a non-transparent liquid that has the property of reflecting or absorbing visible light. Specifically, white ink reflects all visible light, black ink absorbs all visible light, and other colored inks reflect some visible light and absorb other visible light. In other words, colored ink is a liquid with a color that can be perceived through human vision.

On the other hand, transparent ink is an example of a transparent liquid that has the property of transmitting visible light. In other words, transparent ink is ink that does not reflect or absorb visible light. In other words, transparent ink is ink that has the property of reflecting or absorbing specific invisible light (eg, ultraviolet rays, infrared rays, X-rays, gamma rays, etc.). That is, the transparent ink is a liquid that is imperceptible to the human eye and perceptible by the reading unit 250 .

The reading unit 250 is a scanner capable of reading transparent ink that has landed on the continuous sheet S. As shown in FIG. If the transparent ink has a property of reflecting ultraviolet rays, the reading unit 250 includes, for example, an LED that outputs ultraviolet rays toward the continuous sheet S and a photodiode that receives the ultraviolet rays reflected by the continuous sheet S. . Thus, the specific configuration of the reading unit 250 is appropriately selected according to the properties of the transparent ink.

Drying section 260 includes a first drying section 261 and a second drying section 262 . The first drying section 261 dries the ink that has landed on the surface of the continuous sheet S. As shown in FIG. The second drying section 262 dries the ink that has landed on the back surface of the continuous sheet S. The drying section 260 can employ a known configuration, and may include, for example, a heating drum arranged near the conveying path P, or a fan for blowing the continuous sheet S, or the like.

The components of the inkjet printer 100 are arranged in the positional relationship shown in FIG. 2, for example. However, the positional relationship of each component is not limited to the example of FIG. 2, and any arrangement that allows each component to play its role can be adopted. Also, some of the components shown in FIG. 2 can be omitted without departing from the scope of the present invention.

The surface recording unit 220, the back surface recording unit 230, and the plot recording head 240 are all arranged above the transport path P, and eject ink from the same direction (upward) onto the continuous sheet S on the transport path P. do. However, the arrangement of the back surface recording section 230 is not limited to the example in FIG. As another example, the back surface recording unit 230 is arranged on the opposite side of the transport path P to the front surface recording unit 220 (that is, below the transport path P), and is arranged with respect to the continuous sheet S on the transport path P. Ink may be ejected from below. In this case, the reversing mechanism 216 is omitted.

The front surface recording unit 220 is downstream of the transport roller 211 in the transport path P and upstream of the transport path P from the transport roller 212 , the reversing mechanism 216 , the back surface recording unit 230 , the plot recording head 240 , the reading unit 250 and the drying unit 260 . placed on the side. The back surface recording unit 230 is downstream of the transport roller 211 , the reversing mechanism 216 , the front surface recording unit 220 , the plot recording head 240 , the reading unit 250 , and the first drying unit 261 on the transport path P. It is arranged on the upstream side of the transport path P from the portion 262 .

When the ejection receiving medium is a continuous sheet, the front side recording section 220 and the back side recording section 230 are realized by independent hardware. On the other hand, when the ejection receiving medium is cut paper, the front side recording section 220 and the back side recording section 230 may be realized by common hardware (hereinafter referred to as "image recording section (liquid ejection section)"). . In this case, the inkjet printer 100 is equipped with a switchback path (reversal transport path) that reverses the cut paper on which an image has been recorded by the image recording unit and guides it to the position facing the image recording unit again.

The plot recording head 240 is downstream of the transport roller 211 and the surface recording unit 220 in the transport path P, and upstream of the transport roller 212 , the reversing mechanism 216 , the back surface recording unit 230 , the reading unit 250 and the drying unit 260 . are placed in However, the arrangement of the plot recording head 240 is not limited to the above example. As another example, the plot recording head 240 may be arranged on the upstream side of the conveying path P from the surface recording section 220 and eject transparent ink onto the rear surface of the continuous sheet S on the conveying path P. FIG. That is, it is not limited to the surface of the continuous sheet S that the transparent ink lands.

The reading unit 250 is downstream of the transport roller 211, the reversing mechanism 216, the surface recording unit 220, the plot recording head 240, and the first drying unit 261 on the transport path P, and includes the transport roller 212, the back surface recording unit 230, and the second drying unit 261. It is arranged on the upstream side of the transport path P from the drying section 262 . The reading unit 250 is arranged on the opposite side of the plot recording head 240 across the transport path P, and reads the transparent ink that has landed on the surface of the continuous sheet S from below the transport path P. However, the arrangement of the reading unit 250 is not limited to the above example. As another example, the reading unit 250 may be arranged on the upstream side of the transport path P from the reversing mechanism 216 and on the same side of the transport path P as the plot recording head 240 .

As shown in FIG. 3, the plot recording head 240 ejects transparent ink to a plurality of target positions within the image recording area indicated by the broken lines in the continuous sheet S, thereby forming a plurality of transparent plots P ₁₁ to P ₄₃ . Record. The image recording area is, for example, an area where colored ink ejected from the surface recording section 220 can land. Further, the image recording area is, for example, an area that becomes cut paper of a predetermined size (for example, A3, A4, B5, etc.) after the continuous sheet S is cut.

The target position is a position where the image recording area can be divided into a plurality of small areas. In the example of FIG. 3, the small area is a rectangle (rectangle, square). Then, the target position is set to the position of the vertex of the small area. Hereinafter, the shape of the small area connecting the target positions is referred to as "target shape". However, the target shape of the small area is not limited to a rectangle.

Further, in the example of FIG. 3, the target positions are set at four locations (12 locations in total) in the transportation direction at each of the left end, the center, and the right end in the width direction (main scanning direction) perpendicular to the transportation direction. That is, in the example of FIG. 3, the image recording area is divided into six small areas. Furthermore, the target positions are set at regular intervals within the image recording area, for example. That is, in the example of FIG. 3, all small regions have the same shape and size. However, the shape and size of the small regions may be different from each other.

The target position is specified by coordinates (distances in the transport direction and the width direction) with reference to a predetermined origin O on the continuous sheet S. As shown in FIG. The coordinates of each target position are stored in advance in the storage unit (RAM 120, ROM 130, HDD 140). That is, the controller reads out the coordinates of the target position from the storage unit, and reads the image indicating the origin O (indicated by ♦ in FIG. 3) with the scanner. Then, the controller causes the plot recording head 240 to eject clear ink so that the clear ink lands on the continuous sheet S at positions separated from the origin O by the coordinates of each target position.

4 and 5 are diagrams showing variations of target positions stored in the storage unit. The storage unit stores a coordinate set of M first target positions and a coordinate set of N second target positions. For example, FIG. 4 exemplifies the arrangement of the first target positions when M=12. Moreover, FIG. 5 exemplifies the case where N is 20. As shown in FIG. That is, M<N, and at least a portion of the first target position and the second target position are different positions. However, the number of coordinate sets stored in the storage unit and the number and arrangement of coordinates (that is, target positions) included in each coordinate set are not limited to the examples in FIGS.

The transparency plots P ₁₁ -P ₄₃ are mirror-reversed before and after the reversing mechanism 216 . That is, the transparent plot _P11 positioned at the left front end of the image recording area before passing through the reversing mechanism 216 is positioned at the right front end of the image recording area after passing through the reversing mechanism 216 . In other words, the corresponding small areas on the front and back sides of the continuous sheet S are horizontally reversed within the image recording area. The small area surrounded by the transparency plots P ₁₁ , P ₁₂ , P ₂₁ , and P ₂₂ is located at the left front end on the front surface of the continuous sheet S and located at the right front end on the back surface of the continuous paper sheet S.

In the example of FIG. 3, the transparent plots P ₁₁ to P ₄₃ have a "+" shape, but the specific shape is not limited to this. It can be of any shape. As other examples, "●", "♦", etc., or ruled lines (straight lines extending in the transport direction and width direction) forming each side of the small area may be used. Similarly, the image indicating the origin O is not limited to "-". Also, the image showing the origin O may be recorded with colored ink or with transparent ink.

Next, the operation of the inkjet printer 100 according to this embodiment will be described with reference to FIGS. 6 and 7. FIG. FIG. 6 is a flowchart of double-sided printing processing. FIG. 7 is a flowchart of image transformation processing. The double-sided printing process in FIG. 6 is started, for example, when an instruction to record images on both sides of the continuous form sheet S is input through the operation panel 150 .

First, the controller of the inkjet printer 100 records the image instructed by the operator on the surface of the continuous sheet S (S601). The process of step S601 is an example of the first ejection step. Specifically, the controller drives the conveying motor to cause the conveying rollers 211 and 212 to convey the continuous sheet S, and applies a driving voltage to the recording heads 221 to 224 at predetermined timings to eject colored ink.

Next, the controller compares the unevenness of the amount of impact of the colored ink on the surface of the continuous sheet S with a predetermined threshold value (S602). Then, when the controller determines that the deviation of the impact amount is less than the threshold (S602: Yes), it reads the coordinate set of the first target position shown in FIG. 4 from the storage unit (S603). On the other hand, when the controller determines that the deviation of the impact amount is equal to or greater than the threshold value (S602: No), it reads the coordinate set of the second target position shown in FIG. 5 from the storage unit (S604). Steps S603 and S604 are an example of a read step. In this embodiment, the following processing will be described assuming that the coordinate set shown in FIG. 4 has been read.

As an example, the controller divides the image data into a plurality of unit areas, and integrates the amount of ink that has landed on each unit area. Then, the controller may calculate the difference in the amount of impact between the unit area with the largest amount of impact and the unit area with the smallest amount of impact as the "bias in amount of impact". Note that the unit area may have a shape and size different from those of the small areas described above.

As another example, the controller may determine that the deviation of the impact amount is less than the threshold when the image to be recorded on the surface includes only one of patterns (for example, photographs, illustrations) and characters (S602: Yes ). On the other hand, the controller may determine that the deviation of the impact amount is equal to or greater than the threshold when the image to be recorded on the surface includes both a pattern and characters (S602: No). However, the specific method of determination in S602 is not limited to these.

Next, the controller records a transparent plot on the surface of the continuous sheet S by causing the plot recording head 240 to eject transparent ink at a plurality of target positions indicated by the coordinate sets read in steps S603 and S604. (S605). The process of step S605 is an example of the transparent liquid ejection step. Specifically, the controller drives the conveying motor to cause the conveying rollers 211 and 212 to convey the continuous sheet S, and applies a drive voltage to the plot recording head 240 at a predetermined timing to eject clear ink.

FIG. 8 is a diagram showing a state in which images and transparency plots P ₁₁ to P ₄₃ are recorded on the surface of the continuous sheet S. As shown in FIG. The image shown in FIG. 8 includes a bar graph pattern and a character string represented by "x". That is, the left front end region where the bar graph is printed has a large amount of colored ink, the right rear end region where only characters are printed has a small amount of colored ink, and the left rear end region where nothing is printed is colored. Ink has not landed. Also, in the example of FIG. 8, the transparency plots P ₁₁ to P ₄₃ are not recorded overlapping the image, but even if the transparency plots P ₁₁ to P ₄₃ overlap the image, there is no effect on the visibility of the image. .

Next, the controller causes the first drying unit 261 to dry the colored ink and the transparent ink that have landed on the surface of the continuous sheet S (S606). Next, the controller causes the reversing mechanism 216 to reverse the continuous sheet S (S607). FIG. 9 shows the positions of the transparency plots P ₁₁ -P ₄₃ after drying the continuous sheet S of FIG. In FIG. 9, the transparent plots P ₁₁ to P ₄₃ recorded on the front surface of the continuous sheet S are shown as seen through from the rear surface side. Therefore, in FIGS. 8 and 9, the positions of the transparency plots P ₁₁ to P ₄₃ are horizontally reversed.

The ink used to record the image on the surface is absorbed to some extent from the surface of the continuous sheet S and dried. This drying causes the continuous sheet S to expand and contract. The direction and amount of expansion and contraction differ depending on the type of the continuous form sheet S. For example, the larger the amount of ink impacted, the larger the amount of contraction, and the contraction is greater in the width direction than in the transport direction. Therefore, part of the transparent plots P ₁₁ to P ₄₃ recorded at the target positions in step S605 shifts from the recorded positions due to the expansion and contraction of the continuous sheet S. FIG.

In FIG. 9, the transparent plot indicated by black cross-shaped marks indicates the actual position of the transparent plot after the ink that has landed on the continuous sheet S is dried. The position displaced due to expansion and contraction of the continuous sheet S due to drying is referred to as the "actual position". On the other hand, the transparency plot indicated by a white cross-shaped mark indicates the target position of the transparency plot. That is, in the illustration of FIG. 9, the transparency plots P ₁₁ , P ₁₃ , P ₂₃ to P ₄₁ match the target position and the actual position. On the other hand, transparent plots P ₁₂ , P ₂₁ , and P ₂₂ do not exist at the target positions, and are located at actual positions as transparent plots P′ ₁₂ , P′ ₂₁ , and P′ ₂₂ . The shape of the small area connecting the transparent plots at the actual positions is referred to as "real shape".

More specifically, on the surface of the continuous sheet S shown in FIG. 8, the left front end region where the bar graph is recorded locally shrinks significantly. Therefore, after executing step S606, the transparency plots _P12 , _P21 , and _P22 recorded near the bar graph are displaced toward the transparency plot _P11 as shown in FIG. As a result, small regions (hereinafter referred to as “shrinking regions”) whose vertices are the transparent plots P ₁₁ , P ₁₂ , P ₂₁ , and P ₂₂ are deformed (reduced in the example of FIG. 9) by executing step S606. do.

On the other hand, since the continuous form sheet S is restrained by various rollers of the conveying section 210, the outer dimensions of the continuous form sheet S hardly change. Therefore, the positions of the transparency plots P ₁₁ , P ₁₃ , P ₄₁ , and P ₄₃ located at each vertex of the image recording area hardly change. As a result, the small regions adjacent to the contracted region are deformed (shape change and area increase in the example of FIG. 9) by execution of step S606.

Next, the controller executes the image deformation processing shown in FIG. 7 (S608). The image transformation process is a process of individually calculating the landing positions of colored ink for each of a plurality of small regions on the back surface based on the difference between the target positions and the actual positions of the transparency plots _P11 to _P43 . More specifically, the image transformation process transforms the image to be recorded in each of the plurality of small areas from the target shape to the actual shape, and adjusts the impact position so that the transformed image is recorded on the back side. It is a process of calculating.

First, the controller controls the origin O recorded on the surface of the continuous sheet S and the transparency plots P ₁₁ , P' ₁₂ , P ₁₃ , P' 21 , P' ₂₂ , P ₂₃ , P ₃₁ , P ₃₂ , P ₃₂ , P ₃₃ , P ₄₁ , P ₄₂ and P ₄₃ are read by the reading unit 250 (S701). The processing of step S701 is an example of the reading step. Also, the controller substitutes an initial value (=1) for the variable n stored in the RAM 120 (S702). A value specifying the n-th small area to be processed among the plurality of small areas in the image recording area is substituted for the variable n.

In FIG. 9, the small regions with the transparent plots P ₁₁ , P′ ₁₂ , P′ ₂₁ and P′ ₂₂ as vertices are referred to as “first small regions”, and the transparent plots P′ ₁₂ , P ₁₃ , P′ ₂₂ , A small region having _P23 as a vertex is denoted as "second small region", and a small region having transparent plots _P'21 , _P'22 , _P31 , and _P32 as vertices is denoted as "third small region". , transparent _plots P′ ₂₂ , P ₂₃ , P ₃₂ , and _{P 33} as vertices _is referred to as _a “fourth small region”, The region will be referred to as a "fifth small region", and the small regions whose vertices are the transparent plots _P32 , _P33 , _P42 , and _P43 will be referred to as a "sixth small region".

Next, the controller calculates the coordinates of the actual positions of the transparent plots P ₁₁ , P′ ₁₂ , P′ ₂₁ , and P′ ₂₂ , which are the vertices of the first small area, in the coordinate system based on the origin O ( S703). More specifically, the controller may calculate the distances between the origin O and each transparent plot P ₁₁ , P′ ₁₂ , P′ ₂₁ , P′ ₂₂ in the transport direction and width direction.

Next, the controller compares the coordinates of the target position included in the coordinate set read in steps S603 and S604 with the coordinates of the actual position calculated in step S703 for the transparency plot of each vertex of the first small region ( S704). In other words, the controller determines whether the shape and size of the first small region have changed before and after step S606.

The controller determines that the shape of the first small region has changed because the transparent plots P' ₁₂ , P' ₂₁ , and P' ₂₂ at the actual positions are shifted from the target positions (S704: No). Then, the controller transforms the image to be recorded in the first small area of the continuous form sheet S from the target shape of the first small area to the actual shape (S705). Further, the controller calculates the landing positions of the colored inks for drawing the image so that the image deformed to the actual shape is recorded on the back surface of the continuous form sheet S. The specific processing contents for deforming the image will be described later.

Next, the controller determines whether or not the processes of steps S703 to S705 have been executed for all small areas (S706). Then, when the controller determines that the processing of steps S703 to S705 has not been executed for some of the small areas (S706: No), it increments the variable n (S707), and The processing after step S703 is executed. On the other hand, when the controller determines that the processes of steps S703 to S705 have been executed for all small areas (S706: Yes), it ends the image deformation process. The processing of steps S703 to S705 is an example of calculation steps.

In this embodiment, the controller determines that the shapes of the first to fourth small areas have changed (S704: No), and changes the image to be recorded in the first to fourth small areas on the back side from the target shape to the actual shape. Transform (S705). On the other hand, the controller determines that the shapes of the fifth and sixth small regions have not changed (S704: Yes), and proceeds to step S706 without executing the processing of step S705 for the fifth and sixth small regions. move on.

The processing of step S705 is realized by a combination of known image processing. As an example, when the target shape and the actual shape are similar like the first small area, the controller may thin out (interpolate) pixels according to the reduction ratio (enlargement ratio). On the other hand, when the target shape and the actual shape are accompanied by shape changes like the second to fourth small regions, the controller may use a known image conversion algorithm such as trapezoidal correction.

Next, returning to FIG. 6, the controller records the image transformed by the image transformation process on the back side of the continuous sheet S (S609). The process of step S609 is an example of the second ejection step. Specifically, the controller drives the conveying motors to cause the conveying rollers 211 and 212 to convey the continuous sheet S, and at the timing when the colored ink lands on the landing positions calculated in step S705, the recording heads 231 to 234 A drive voltage is applied to eject colored ink.

Next, the controller causes the second drying unit 262 to dry the colored ink that has landed on the back surface of the continuous sheet S (S610). Then, the controller causes the area of the continuous form sheet S on which the image is recorded to be taken up by the conveying roller 212, and completes the double-sided printing process.

According to the above embodiment, the landing position of the ink on the back surface can be adjusted in detail with respect to the ink that has landed on the front surface. More specifically, it is possible to finely adjust the landing positions of the ink used for recording the image on the back side based on the actual amount of expansion and contraction of the continuous form sheet S due to the recording of the image on the front side. For example, the following effects are obtained.

According to the above embodiment, the expansion and contraction of each small area of the continuous sheet S due to the colored ink that has landed on the front side is detected as the difference between the target position and the actual position of the transparent ink (transparent plot). The landing position can be adjusted for each small area. Since the transparent ink does not overwrite the colored ink, the transparent ink can be ejected to any position on the continuous form sheet S (for example, the image recording area). As a result, the degree of freedom in setting small areas on the continuous sheet S increases.

Further, according to the above-described embodiment, an image deformed according to the expansion and contraction of each small area is recorded on the back surface of the continuous sheet S. Here, the continuous sheet S released from the restraint by the conveying section 210 tries to return to the shape before expansion and contraction. Therefore, if a deformed image is recorded on the back side, an image close to the original shape is recorded on the back side of the continuous feed sheet S ejected from the inkjet printer 100 .

In addition, areas with a large amount of colored ink deposited tend to have a large amount of expansion and contraction, and areas with a small amount of colored ink deposited tend to have a small amount of expansion and contraction. Therefore, if the impact amount of the colored ink is unevenly distributed, the expansion/contraction difference between the small regions becomes large. In such a case, it is desirable to flexibly cope with local expansion and contraction of the continuous sheet S by increasing the number of small areas. On the other hand, when the bias in the ejection amount of the colored ink is small, the difference in expansion and contraction for each small area is small. In such a case, it is desirable to reduce the number of sub-regions to reduce the amount of computation of the controller.

Further, the amount of expansion and contraction of the continuous sheet S increases as the color ink that has landed is dried. Therefore, by applying the present invention to the inkjet printer 100 having the drying section 260, a particularly remarkable effect can be expected. However, the present invention can also be applied to the inkjet printer 100 that naturally dries while being conveyed by the conveying unit 210 instead of being actively dried by the drying unit 260 . That is, the drying section 260 can be omitted.

It should be noted that the present invention is not limited to a liquid ejection apparatus represented by the inkjet printer 100, but is also conceived as a liquid ejection method for ejecting liquid onto the front and back surfaces of an ejection receiving medium as shown in FIGS. be able to.

In addition, the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the technical scope of the invention. All of are covered by the present invention. Although the above embodiment shows a preferred example, a person skilled in the art can realize various modifications from the disclosed contents. Such modifications are also included in the technical scope described in the claims.

100 inkjet printer 110 CPU
120 RAMs
130 ROMs
140 HDDs
150 Operation panel 160 I/F
180 common bus 210 conveying unit 216 reversing mechanism 220 surface recording unit 230 back surface recording unit 240 plot recording head 250 reading unit 260 drying unit

JP 2016-182759 A

Claims (9)

A liquid ejecting apparatus that ejects liquid onto the front and back surfaces of a medium to be ejected,
a storage unit that stores a target position on the ejection receiving medium;
a first ejection unit that ejects a non-transparent liquid that reflects or absorbs visible light onto the surface of the ejection receiving medium;
a transparent liquid ejection unit that ejects a transparent liquid that transmits visible light to the target position on the surface read from the storage unit in order to divide the ejection receiving medium into a plurality of small areas;
a reading unit that reads an actual position of the transparent liquid that has landed on the ejection receiving medium after the non-transparent liquid is ejected by the first ejection unit;
Based on the difference between the target position read from the storage unit and the actual position read by the reading unit, the non-transparent liquid is applied to each of the small regions of the back surface corresponding to the plurality of small regions. a computing unit that computes the impact position individually;
and a second ejection unit configured to eject the non-transparent liquid onto the back surface of the ejection receiving medium so as to land on the landing position calculated by the calculation unit. The transparent liquid ejecting unit ejects the transparent liquid onto a plurality of target positions corresponding to vertices of each of the small regions of the surface, respectively, and
For each of the plurality of small regions on the back surface, the computing unit
transforming an image to be recorded in the small area from a target shape connecting the plurality of target positions corresponding to each vertex to a real shape connecting the plurality of actual positions corresponding to each vertex;
2. The liquid ejecting apparatus according to claim 1, wherein the landing position is calculated so that the image deformed to the actual shape is recorded on the back surface. The computing unit identifies the actual shape by computing the coordinates of each of the plurality of actual positions corresponding to each vertex in a coordinate system based on a predetermined origin on the ejection receiving medium. 3. The liquid ejecting apparatus according to claim 2, characterized by: The storage unit
a first target position that divides the ejection receiving medium into the M small areas;
partitioning the ejection receiving medium into N (N>M) small areas and storing a second target position different from the first target position;
The transparent liquid ejection part is
ejecting the transparent liquid onto the first target position on the surface read from the storage unit when the non-transparent liquid impact amount bias on the surface is less than a threshold;
3. The liquid ejecting apparatus according to claim 1, wherein the transparent liquid is ejected to the second target position on the surface read out from the storage unit when the deviation of the landing amount is equal to or greater than a threshold. a transport unit that transports the ejection target medium along a transport path;
A drying unit is provided downstream of the first ejection unit in the transport path and upstream of the transport path from the reading unit, and dries liquid that has landed on the surface of the ejection receiving medium. 5. The liquid ejecting apparatus according to any one of claims 1 to 4. The transparent liquid ejection section is arranged downstream of the first ejection section in the transport path and ejects the transparent liquid onto the surface;
6. The liquid ejecting apparatus according to claim 5, wherein the drying section dries the non-transparent liquid and the transparent liquid that have landed on the surface of the ejection receiving medium. A transport unit that transports the ejection receiving medium along a transport path,
7. The apparatus according to any one of claims 1 to 6, wherein the second discharge section is provided independently of the first discharge section downstream of the first discharge section in the conveying path. A liquid ejection device as described. The conveying unit includes a reversing mechanism for reversing the ejection receiving medium between the first ejecting unit and the second ejecting unit,
8. The liquid ejection apparatus according to claim 7, wherein the first ejection section and the second ejection section eject the non-transparent liquid from the same direction with respect to the transport path. A liquid ejection method for ejecting liquid onto the front and back surfaces of a medium to be ejected, comprising:
a reading step of reading a target position on the ejection receiving medium;
a first ejection step of ejecting a non-transparent liquid that reflects or absorbs visible light onto the surface of the ejection receiving medium;
a transparent liquid ejecting step of ejecting a transparent liquid that transmits visible light to the target position of the surface read in the reading step in order to divide the ejection receiving medium into a plurality of small areas;
a reading step of reading an actual position of the transparent liquid that has landed on the ejection receiving medium after the non-transparent liquid is ejected in the first ejection step;
Based on the difference between the target position read out in the reading step and the actual position read out in the reading step, the non-transparent region corresponding to each of the plurality of small regions on the back surface is determined. a calculation step of individually calculating the landing position of the liquid;
and a second ejection step of ejecting the non-transparent liquid onto the back surface of the ejection receiving medium so as to land on the landing position calculated in the calculation step.

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