JP7650194B2 - Inkjet recording apparatus and method - Google Patents

Description

The present invention mainly relates to an inkjet recording device.

Generally, when ink is applied to a recording medium, a difference in expansion and contraction occurs between the surface to which the ink is applied and the opposite surface, which can cause deformation (curving) of the recording medium. This can cause unexpected transport problems in the transport mechanism within the recording device. Patent Document 1 describes a recording device capable of double-sided printing, in which a waiting time is set after recording on the first side is completed and before recording on the second side begins, based on the amount of ink applied to the first side.

JP 2012-245674 A

According to the configuration of Patent Document 1, the above-mentioned waiting time is set based on the amount of ink applied to the first side of the recording medium, and the second side is not taken into consideration. This can cause an unnecessary decrease in throughput, so there is room for improvement in terms of improving printing efficiency.

The present invention aims, for example, to prevent transport problems caused by deformation of the recording medium while suppressing a decrease in throughput in a recording device capable of double-sided printing.

One aspect of the present invention relates to an inkjet recording apparatus, comprising:
An inkjet recording apparatus capable of double-sided printing,
a recording head capable of recording by applying ink to a first surface and a second surface of a recording medium;
A conveying mechanism for conveying the recording medium;
A recording control unit,
The recording control unit
a first process for acquiring first information indicating an amount of ink applied to a first region on the first surface and second information indicating an amount of ink applied to a second region on the second surface, the second region being located on the opposite side to the first region;
a second process of printing on the first side while transporting the recording medium on a first transport path, and then inverting the recording medium and transporting the recording medium on a second transport path while printing on the second side;
providing a waiting time based on the first information and the second information acquired in the first process when the recording medium is conveyed by the conveying mechanism after the printing on the first side in the second process is completed ;
The recording control unit is characterized in that, in the second processing, it determines whether the second information is necessary based on the first information, and if it is determined that the second information is necessary, it sets the waiting time based on the first information and the second information .

The present invention makes it possible to prevent transport problems caused by deformation of the recording medium while suppressing a decrease in throughput.

FIG. 1 is a schematic diagram illustrating an example of the configuration of a recording apparatus according to an embodiment. 1A and 1B are schematic diagrams showing deformation modes of a recording medium. FIG. 4 is a schematic diagram showing an example of an area for acquiring an amount of applied ink. FIG. 4 is a diagram illustrating an example of a table used for transport control according to the embodiment. 13A and 13B are schematic diagrams showing other examples of areas for acquiring the amount of applied ink. FIG. 11 is a diagram showing another example of a table used for transport control. FIG. 11 is a diagram showing another example of a table used for transport control. FIG. 11 is a diagram showing another example of a table used for transport control. FIG. 13 is a schematic diagram for explaining an example of a transportation malfunction. 3A and 3B are schematic diagrams illustrating configuration examples of a paper discharge unit and a handle unit. 1A and 1B are diagrams illustrating examples of stop positions for conveying a recording medium in a recording apparatus.

The following embodiments are described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe multiple features, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicate explanations are omitted.

FIG. 1(a) is a simplified schematic diagram showing an example of the internal configuration of a recording device 900 according to an embodiment. The recording device 900 includes a pickup roller 1, a supply unit 2, a pair of transport rollers 3 and 4, a recording head 5, a transport path switching unit 6, a discharge unit 7, a discharge tray 8, and a recessed portion 9.

In this embodiment, the recording device 900 is an inkjet recording device that performs recording using an inkjet recording method. The recording device 900 is also configured to be able to change the posture of a sheet-like recording medium P (typically paper) using the transport roller pairs 3 and 4 and the transport path switching unit 6, and perform recording on both sides of the recording medium P using the recording head 5. That is, the recording device 900 can perform recording on one side of the recording medium P using the transport roller pairs 3 and 4 (single-sided printing), and can also perform recording on the other side of the recording medium P using the transport path switching unit 6 (double-sided printing).

The recording head 5 is configured to be long so that it can perform recording across the entire width of the recording medium P at once. Such a recording head 5 can also be referred to as a line head, full line head, etc.

First, the operation in the case of single-sided printing will be described. The recording medium P is picked up by the pickup roller 1 from the supply unit 2 that supplies the recording medium P and supplied. The supplied recording medium P is conveyed at a predetermined speed in the direction of the arrow Y (conveyance direction) while being sandwiched between the conveyance roller pairs 3 and 4 along the conveyance path indicated by the arrow X, and during this conveyance, the recording head 5 records on the recording medium P. The recording medium P is then output or discharged via the discharge unit (which may be expressed as an "discharge port"; in this embodiment, since the recording medium P is paper, it may also be expressed as a "paper discharge port") 7 to the discharge table (which may be expressed as an "discharge unit"; in this embodiment, since the recording medium P is paper, it may also be expressed as a "paper discharge unit") 8.

The recess 9 is a depression recessed into the top surface of the paper discharge section 8. To make it easier for the user to remove the recording medium P that has been output or discharged to the paper discharge section 8, the recess 9 is provided on the front side of the main body, which is the removal direction of the recording medium P, so that the user can access the lower side of the recording medium P with their hands. This recess 9 is also called a handhold.

The recording head 5 is disposed between a pair of conveying rollers 3 on the upstream side of the conveying direction (the supply section 2 side of the conveying path) and a pair of conveying rollers 4 on the downstream side (the discharge section 7 side of the conveying path). The recording head 5 ejects ink of four colors, K (black), C (cyan), M (magenta) and Y (yellow), toward the recording medium P based on the recording data input to the recording device 900. Here, the recording head 5 is provided with a plurality of elements that generate energy for ejecting ink, such as electrothermal conversion elements (heaters) and piezoelectric elements, as recording elements, and the recording head 5 ejects ink from the ejection openings (nozzles) using the plurality of recording elements. A plurality of such ejection openings are arranged along a direction that intersects (substantially perpendicular in this example) with the conveying direction of the recording medium P, and they form an ejection opening row (nozzle row).

Next, the transport path of the recording medium P in double-sided printing will be described. First, recording is performed on one side (back side) of the recording medium P in the same procedure as in single-sided printing, and then the transport path of the recording medium P is switched by the transport path switching unit 6, and recording is performed by the recording head 5 on the other side (front side) of the inverted recording medium P.

Specifically, after the rear end of the recording medium P passes through the conveying path switching unit 6, the conveying of the recording medium P is temporarily stopped, and the conveying path switching unit 6 switches the conveying path so that the recording medium P is conveyed in the direction of the arrow Z. As a result, the recording medium P is conveyed to the switched conveying path. The recording medium P is conveyed in the direction of the arrow Z, passes through the conveying roller pairs 3 and 4 again in an inverted state, and after the recording head 5 performs recording on the back side, it is discharged to the discharge unit 8 via the paper discharge port 7. In this way, the recording medium P is discharged with the front side facing down (towards the discharge unit 8). When the user removes the recording medium P from the discharge unit 8, he or she can simply pick up the recording medium P with its bottom side facing the user. In addition, when printing multiple sheets of the recording medium P, by printing with each front side facing down, the multiple sheets of the recording medium P are stacked in page order, with the discharge unit 8 side being the first page.

FIG. 1B is a block diagram showing an example of the system configuration of the recording device 900. The recording device 900 further includes a main control unit 20, a transport motor 26, and a personal computer (PC) 29.

The main control unit 20 comprises a CPU (recording control unit) 21, a ROM 22, a RAM 23, an EEPROM 24, and an input/output port 25. The CPU 21 executes processing operations such as calculation, selection, judgment, and control to realize each function described in this specification. The ROM 22 stores control programs to be executed by the CPU 21. The RAM 23 is used as a buffer for recording data. The EEPROM 24 stores image data and mask patterns. In addition, a drive circuit 27 corresponding to a conveying motor (which can also be expressed as a line feed (LF) motor) 26 is connected to the input/output port 25, and a drive circuit 28 corresponding to the recording head 5 is also connected. The PC 29 is also expressed as a host computer (host device), and the PC 29 is connected to the main control unit 20.

Figures 2(a) to 2(c) are schematic diagrams for explaining deformation (curl) that may occur in recording medium P when ink is applied to the recording medium P. Figure 2(a) shows an example of an aspect in which an image 201 is recorded and ink is applied to the leading edge (downstream side) of the recording medium P in the discharge direction. In this embodiment, the recording medium P on which the image 201 is recorded is discharged to the paper discharge section 8 so that the side on which the image 201 is recorded faces downward.

2B is a schematic diagram showing the recording medium P discharged to the paper discharge section 8 and the accompanying image (ink application section) 201 from the viewpoint of the horizontal direction of the recording medium P and the width direction of the recording medium P. FIG. 2C is a schematic diagram showing the recording medium P discharged to the paper discharge section 8 and the image 201 from the viewpoint of the horizontal direction of the recording medium P and the conveying direction of the recording medium P. When ink is applied to the recording medium P, the recording medium P is deformed as shown in FIG. 2C due to the difference in expansion and contraction (difference in expansion and contraction rate) of the recording medium P that may occur between the front side to which ink is applied and the back side to which ink is not applied. This difference in expansion and contraction is caused by the difference in the amount of ink applied between both sides (front and back). In general, the individual elements and conveying paths of the recording device 900, such as the paper discharge port 7 and the paper discharge section 8, are required to be designed so that paper jams (so-called jams) do not occur during the conveying of the recording medium P even if such deformation occurs.

The degree of deformation (amount of deformation) may vary depending on the time that has passed since ink was applied to the recording medium P. Immediately after ink is applied to the recording medium P, the difference in expansion and contraction between the two sides of the recording medium P is small or practically nonexistent, so the amount of deformation is small or practically nonexistent. This amount of deformation then increases over time. As time passes, the ink applied to the surface penetrates (deeply) into the interior of the recording medium P, reducing the difference in expansion and contraction between the two sides of the recording medium P, and the amount of deformation gradually decreases.

As described with reference to Figures 2(a) to 2(c), deformation of the recording medium P occurs due to the difference in the amount of ink applied between both sides (front and back). On the other hand, if the amount of ink applied to both sides is relatively large, the difference in expansion and contraction that can occur between the two sides of the recording medium P becomes small, so the above deformation is less likely to occur or does not actually occur. In the following description, the first side will be referred to as the side that is printed first (here, the back side), and the second side will be referred to as the side that is printed after the first side (here, the front side).

In addition, if the amount of ink applied to the second side (front side) is greater than the amount of ink applied to the first side (back side), the direction of deformation of the recording medium P will be the same as in the case of single-sided printing. Therefore, even if the configuration of the recording device 900 is the conventional one (dedicated for single-sided printing), the recording medium P can be transported properly. However, if the amount of ink applied to the first side (back side) is greater than the amount of ink applied to the second side (front side) by more than a certain amount, the recording medium P may deform in the opposite direction to the case of single-sided printing. Therefore, a transport malfunction such as a jam may occur at any position within the recording device 900 during transport, or at the paper discharge port 7 or paper discharge unit 8 during discharge. Specific examples of places where such a transport malfunction may occur include the transport path switching unit 6 in FIG. 1(a) and the handle unit 9 provided in the paper discharge unit 8.

The causes of the jams described above are described below. Figures 9(a) to 9(f) are schematic diagrams for explaining the method of switching the transport path by the transport path switching unit 6 and the effect of deformation of the recording medium P during the switching.

Figure 9(a) shows the state of the transport path switching unit 6 when the printed recording medium P is transported in the discharge direction (from bottom to top in the figure). The transport path switching unit 6 includes a switching member 601 as a mechanism capable of switching the transport path, and a switching member support unit 602 that rotatably supports the switching member 601, and the transport path of the recording medium P is selectively guided by rotating the switching member 601. The transport path when performing double-sided printing (i.e., the path in direction Z) is closed by the transport switching member 601.

Figure 9 (b) shows the state of the transport path switching unit 6 when the recording medium P is guided to the transport path (path in the direction of the arrow Z) for double-sided printing. The switching member 601 rotates around the switching member support part 602 to block the transport path to the recording head 5. As a result, the recording medium P that has passed through the transport path switching unit 6 and been guided upward in the discharge direction is transported from the top to the bottom in the figure (in the reverse direction) and is guided to the transport path in the direction of the arrow Z.

Figure 9(c) shows a state in which a jam occurs, as one type of transport malfunction that can occur when the recording medium P is transported in the reverse direction. If the above-mentioned deformation occurs in the recording medium P, as shown in Figure 9(c), there is a possibility that the leading edge of the recording medium P transported from the top to the bottom in the figure will interfere with the switching member 601. As a result, the leading edge of the recording medium P is bent by the switching member 601, causing a transport malfunction (here, a jam).

Figure 9 (d) is a schematic diagram showing an example of the configuration of the transport path switching unit 6 for preventing the occurrence of the above-mentioned transport malfunction. The transport path switching unit 6 may further include a recessed portion 603. The recessed portion 603 is provided so as to be able to avoid interference between the recording medium P and the tip of the switching member 601, and in this embodiment, when the switching member 601 rotates, its tip fits into the recessed portion 603. With this configuration, the tip of the switching member 601 is hidden by the recessed portion 603, making it possible to avoid interference between the recording medium P and the switching member 601.

Figure 9(e) shows the state when a recording medium P with its front side printed is transported to the transport path switching unit 6 in the structure of the transport path switching unit 6 with the recessed portion 603. When printing on the front side is complete, as shown in the figure, ink is applied to the left side of the recording medium P, so the recording medium P deforms on the side opposite the ink application side (see Figures 2(a) to 2(c)). Therefore, as shown in Figure 9(e), the leading edge of the recording medium P is transported without interfering with the recessed portion 603, and no transport problems occur. The same is true when the amount of ink applied to the front side is greater than the amount of ink applied to the back side.

Figure 9(f) shows, like Figure 9(e), a state in which the amount of ink applied to the back surface is greater than the amount of ink applied to the front surface in a structure of a transport path switching unit 6 that includes a recessed portion 603. In this case, the recording medium P will deform in the opposite direction to the example in Figure 9(e), and the leading edge of the recording medium P may interfere with or collide with the recessed portion 603, causing transport problems.

In addition, if the amount of ink applied to the leading edge of the recording medium P in the transport direction is substantially none or relatively small on either side, the above-mentioned deformation does not substantially occur or is unlikely to occur at the leading edge of the recording medium P.

The above-mentioned deformation can cause similar transport problems in the handhold section 9.

Figure 10(a) is a perspective view of a portion of the recording device 900 including the paper discharge port 7, paper discharge section 8, and handle section 9. After recording is completed, the recording medium P is discharged from the paper discharge port 7 and placed on the paper discharge section 8. In this embodiment, as described above, the paper discharge section 8 is provided with the handle section 9 so that the user can relatively easily remove the recording medium P loaded on the paper discharge section 8.

Figure 10(b) is a top view (plan view) of the paper discharge section 8, and Figure 10(c) is a cross-sectional view of the paper discharge section 8 cut along a plane passing through the handle 9. In the case of single-sided printing, or in the case of double-sided printing where the amount of ink applied to the front side is greater than the amount of ink applied to the back side by more than a standard amount, as described above, it can be said that transport problems do not actually occur (see Figure 2(c)). However, in the case of double-sided printing where the amount of ink applied to the back side is greater than the amount of ink applied to the front side by more than a standard amount, the recording medium P is deformed in the opposite direction to the above example (see Figure 2(c)). Therefore, both ends of the downstream side of the recording medium P are discharged from the paper discharge port 7 in a state where they are curved downward, and as a result, the downstream tip of the recording medium P interferes with the handle 9, which may cause transport problems.

(First embodiment)
3A is a schematic diagram showing a first acquisition range W1 for acquiring the amount of ink applied to the first side (here, the back side) as a first embodiment. In this example, after printing on the first side (back side), the conveying direction of the recording medium (paper) P is reversed and printing on the second side (front side) is performed. Therefore, the leading edge of the paper P after printing on the first side (back side) (the downstream edge when ejected with single-sided printing) becomes the trailing edge (the upstream edge) when printing on the second side (front side) after the paper P is turned over and the attitude of the paper P is changed.

As mentioned above, transport problems (e.g. jams) are likely to occur when there is a large amount of deformation at the leading edge in the transport direction (the downstream end). Therefore, the area for acquiring the amount of ink applied should be a specified area at the leading edge in the transport direction when printing on the second surface. In this example, for the acquisition range W1 at the rear end of the first surface (leading edge of the second surface), the average number of ng (nanograms) of ink applied in a 600 dpi x 600 dpi range is acquired.

Like FIG. 3(a), FIG. 3(b) is a schematic diagram showing a second acquisition range W2 for acquiring the amount of ink applied to the second side (front side). The recording medium P passes through the transport path switching unit 6, is turned over, and then recording on the back side begins. At this time, an acquisition range W2 is set on the opposite side of the acquisition range W1, and the average amount of ink applied within the set acquisition range W2 in a range of 600 dpi x 600 dpi is acquired in the same manner as for the first side.

Figure 4 shows a reference table TB4 for transport control corresponding to the ink application amounts for each of the acquisition ranges W1 and W2. Table TB4 is used to set or determine the waiting time after printing of the first side is completed. As shown in Figure 4, the waiting time is set to be longer the greater the ink application amount on the first side is compared to the ink application amount on the second side. In this example, by referring to table TB4, a waiting time is set after printing of the first side is completed (and incidentally before printing of the second side begins) based on the difference in the ink application amounts between the front and back during double-sided printing, and transport of the recording medium P is stopped during that time.

Figure 11 shows positions 1101, 1102, and 1103 as examples of stop positions for the above-mentioned transport of the recording medium P. Stop position 1101 indicates the position after the rear end of the recording medium P has passed the pair of transport rollers 4 after printing on the first side is completed. Stop position 1102 indicates the position where transport is temporarily stopped after the rear end has passed the transport path switching unit 6, and incidentally due to switching of the transport path by the transport path switching unit 6. Stop position 1103 indicates the position before the leading edge of the recording medium P passes again through the pair of transport rollers 3 after being inverted in the transport path switching unit 6 and passing through the transport path for double-sided printing to print on the back side.

In order to appropriately prevent the above-mentioned transport malfunction, it is advisable to provide a waiting time immediately after printing. On the other hand, a certain amount of time is required to calculate, analyze or refer to the amount of ink applied to the second side. Furthermore, when the main body of the recording device 900 is made smaller, the distance from the recording head 5 to the transport path switching unit 6 becomes shorter. In that case, the leading edge of the recording medium P in the transport direction reaches the transport path switching unit 6 (the location where the transport malfunction occurs (see Figure 9)) during recording by the recording head 5. For these reasons, it is even more advisable to set the stop position of the above-mentioned transport for the recording medium P to position 1102.

In the above example, the front side is the second side and the back side is the first side, but if printing on the back side is done before printing on the front side, double-sided printing can be done in the same manner as above, with the back side as the second side and the front side as the first side.

Referring again to FIG. 4 (table TB4), for example, if the amount of ink applied to the first surface in acquisition range W1 is 35 ng, and the amount of ink applied to the second surface in acquisition range W2 is 0 ng, the wait time is set to 9 seconds. After printing on the first surface is completed, a wait time of 9 seconds is set in the transport of the recording medium P before printing on the second surface begins. This allows the ink applied to the first surface to penetrate into the interior of the recording medium P, reducing the difference in expansion and contraction between the front and back of the recording medium P, and once the amount of deformation of the recording medium P has reduced, it becomes possible to properly start printing on the second surface.

As another example, if the amount of ink applied to the first surface in the acquisition range W1 is 35 ng, and the amount of ink applied to the second surface in the acquisition range W2 is 35 ng, the waiting time is set to 0 seconds (i.e., no waiting time is set). If the ink application amounts are equal between the front and back, the difference in expansion and contraction between the front and back of the recording medium P is small or does not occur substantially, and the amount of deformation of the recording medium P is small or does not deform substantially. Therefore, there is no need to set the above-mentioned waiting time. As a result, by considering the amount of ink applied to the second surface in addition to the amount of ink applied to the first surface, the waiting time is not set unnecessarily, and it is possible to prevent unnecessary reductions in throughput during double-sided printing.

As yet another example, if the amount of ink applied to the first surface in acquisition range W1 is 0 ng, and the amount of ink applied to the second surface in acquisition range W2 is 35 ng, the waiting time is set to 0 seconds (i.e., no waiting time is set). If the amount of ink applied to the second surface is large, the recording medium P will deform in the same manner as in single-sided printing. Therefore, in this case, no waiting time is required.

As mentioned above, applying ink to the recording medium P causes deformation of the recording medium P, and then, over time, the ink penetrates into the recording medium P, reducing the deformation. Therefore, a wait based on the above-mentioned waiting time (temporary stop of transport) must be performed after printing on the first side.

If the location where a transport malfunction may occur due to deformation of the recording medium P after double-sided printing is downstream of the position of the leading end of the recording medium P when printing on the second side is completed, a wait may be executed after printing on the second side. However, if the transport path switching unit 6 is located downstream and close to the recording head 5, with the aim of reducing the size of the recording device 900 body, the leading end of the recording medium P may reach the transport path switching unit 6 during printing on the second side, and the above-mentioned transport malfunction (e.g., a jam) may occur. In particular, in this embodiment in which the inkjet recording device 900 is equipped with a line head 5, stopping the recording medium P during printing reduces the quality of the image. Therefore, in such a case, a wait based on the above-mentioned waiting time may be executed before printing on the second side so that transport is not temporarily stopped during printing.

As described above, according to this embodiment, when double-sided printing is performed, the ink application amount for each of the acquisition ranges W1 and W2 is acquired, a waiting time is set based on the acquired ink application amount, and the transport of the recording medium P is temporarily suspended for the waiting time after printing on the first side is completed. This makes it possible to execute a wait according to the ink application amount on the front and back sides of the recording medium P when performing double-sided printing, preventing transport problems during double-sided printing and suppressing a decrease in throughput.

(Second Example)
FIG. 5A is a schematic diagram showing the acquisition ranges W1, L1 (L1 ₁ to L1 ₄ ), and R1 (R1 ₁ to R1 ₄ ) for acquiring the amount of ink applied to the first side (front side) as a second embodiment. As described above, the leading edge of the recording medium (paper) P when printing on the second side (reverse side) corresponds to the trailing edge of the paper P when printing on the first side. Therefore, the acquisition ranges W1 and the like are the trailing edge of the paper P. In addition, the manner in which the aforementioned transport malfunction occurs may differ between the left edge (left leading edge) and the right edge (right leading edge) of the leading edge of the paper P. Therefore, it is advisable to acquire the amount of ink applied for the acquisition ranges W1, L1, and R1.

Furthermore, the leading edge of the recording medium P is more susceptible to deformation of the recording medium P due to the application of ink, so the acquisition range L1 of the left leading edge is divided into four (respectively ranges _L11 , _L12 , _L13 , and _L14 ), and the acquisition range R1 of the right leading edge is divided into four (respectively ranges _R11 , _R12 , _R13 , and _R14 ).

The ink application amounts obtained in the ranges L1 ₁ to L1 ₄ and R1 ₁ to R1 ₄ are normalized by weighting as follows:
L1'=
(L1 ₁ ×4+L1 ₂ ×3+L1 ₃ ×2+L1 ₄ ×1)/(4+3+2+1),
R1'=
(R1 ₁ ×4+R1 ₂ ×3+R1 ₃ ×2+R1 ₄ ×1)/(4+3+2+1).

The above-mentioned load addition and normalization make it possible to perform transport control that further considers the influence of the ink application amount at the end of the recording medium P. In this way, the area from which the ink application amount is obtained may include the leading edge in the transport direction after printing on the second side, or may include multiple adjacent areas. In this example, for each of the acquisition ranges W1, L1, and R1, W1, L1', and R1' are obtained as the print duty of each area (first side duty (first information)).

5(b) is a schematic diagram showing acquisition ranges W2, L2 (L2 ₁ to L2 ₄ ), and R2 (R2 ₁ to R2 ₄ ) for acquiring the amount of ink applied to the second surface, similar to FIG. 5(a). In the same procedure as for acquisition ranges L1 and R1, W2, L2', and R2' are acquired as the print duties of each area for acquisition ranges L2 and R2 (second surface side duty (second information)):
L2'=
(L2 ₁ ×4+L2 ₂ ×3+L2 ₃ ×2+L2 ₄ ×1)/(4+3+2+1),
R2'=
(R2 ₁ ×4+R2 ₂ ×3+R2 ₃ ×2+R2 ₄ ×1)/(4+3+2+1).

For the sake of convenience, in the explanations of this specification, symbols such as L1 and L1' may indicate not only the acquisition range but also the corresponding duty or amount of ink applied.

Figure 6 (a) shows a reference table TB6 for transport control in this example. The aforementioned waiting time is set or determined based on table TB6 according to the first surface side duties W1, L1', and R1' and the second surface side duties W2, L2', and R2'.

Here, when the recording medium (paper) undergoes a difference in expansion and contraction due to the application of ink, it often deforms parallel to its long side (curves in the short side) as shown in FIG. 2(c). Here, transport in the long side direction can be called "vertical transport", and transport in the short side direction can be called "horizontal transport". Considering that the deformed paper P is held or clamped by a transport mechanism such as the transport roller pair 3 while being transported, the "horizontal transport" has a greater effect on the deformation of the paper P than the "vertical transport", which may cause the transport malfunction described above. On the other hand, since the transport distance of a single sheet of paper is shorter in the short side direction, it can be said that "horizontal transport" can improve throughput more than "vertical transport".

In this example, the recording device 900 is configured to be able to perform both "vertical feed conveyance" and "horizontal feed conveyance". In the case of vertical feed conveyance (SEF (Short Edge Feed)), the paper P can be appropriately pressed by a conveyance mechanism such as the conveyance roller pair 3 so as to suppress deformation. Therefore, the above-mentioned conveyance malfunction is unlikely to occur. Therefore, as shown in FIG. 6(a), in the case of SEF, the waiting time is set to 0 seconds. In contrast, in the case of horizontal feed conveyance (LEF (Long Edge Feed)), it is more difficult to press the paper P to suppress deformation than in the case of SEF, so in LEF, the waiting time is set according to the above-mentioned Duty.

As mentioned above, examples of locations where transport malfunctions may occur include the transport path switching unit 6 and the handhold unit 9. The wait times (temporary stop of transport) required for these, i.e., the aforementioned waiting times, may differ from each other. Therefore, in the example of FIG. 6(a), the waiting times to prevent transport malfunctions at the transport path switching unit 6 are set in the B1_W, B1_Left, and B1_Right rows. Also, the waiting times to prevent transport malfunctions at the handhold unit 9 are set in the B2_W, B2_Left, and B2_Right rows.

In "Decision 1" shown in FIG. 6A, it is determined whether or not a wait time is unnecessary based only on the first side duty. If the first side duty (W1, L1', and R1') is less than the threshold value (10% in FIG. 6A), the wait time is set to 0 seconds without referring to the second side duty. This means that if both the first side duty and the second side duty are always referred to (as in the first embodiment), the length of the wait time to be set after printing on the first side cannot be determined until the second side duty is calculated. Therefore, if this wait time is unnecessary, unnecessary calculation time will be generated, which will actually reduce the throughput during double-sided printing. Therefore, if the first surface side duty is low (low duty) and it can be said that there is no need to refer to the second surface side duty, i.e., if it can be determined that no waiting time will occur, it can be determined that there is no need to wait based only on the first surface side duty.

In "Judgment 2" shown in FIG. 6(a), the wait time is set based on both the first side duty and the second side duty. If the first side duty is equal to or greater than the threshold value of "Judgment 1" (10% in this example), "Judgment 2" in table TB6 is referenced, and a wait time is set according to the difference between the first side duty and the second side duty (W1-W2, L1'-L2', and W1'-W2'). Specifically, these differences are compared, and the one determined to be the longest wait time is selectively set.

Figure 6(b) is a diagram to explain some examples of selectively setting the above-mentioned waiting time.

"Example 1" in Figure 6 (b) shows a case where the first side duty is relatively low at 5% (low duty case). In this case, the first side duty is 5%, i.e., less than the threshold value (10%) of "Decision 1" above, so no wait time is required based solely on the first side duty (a wait time of 0 seconds is set). In this way, when the first side duty is low, no wait time is required without referring to the second side duty, so throughput during double-sided printing does not substantially decrease.

"Example 2" in Figure 6 (b) shows a case where the first side duty is relatively high at 70% (high duty case) and the second side duty is 0% (blank) (i.e., a case where printing is done upside down compared to single-sided printing). First, the image data (which can also be expressed as print data, recording data, etc.) used for printing on the first side is processed to obtain the first side duty. The obtained first side duty is higher than the threshold value (10%) of "Decision 1" above. For this reason, it can be said that it is necessary to refer to the second side duty.

The second side duty is obtained by performing image processing on the image data used for printing on the second side during printing on the first side. As a result, the waiting time is set based on the difference (70% in this example) between the first side duty (70% in this example) and the second side duty (0% in this example) (see FIG. 6(a)). In this example, the waiting time is 9 seconds according to B1_W, 9 seconds according to B1_Left, 9 seconds according to B1_Right, 6 seconds according to B2_W, 6 seconds according to B2_Left, and 10 seconds according to B2_Right. The longest of these (10 seconds in this example) is selected and set as the waiting time before printing on the second side begins.

"Example 3" in FIG. 6(b) shows a case where the first side duty is W1 35%, L1 50%, and R1 20%, and the second side duty is 0% (blank). In this case, W1-W2=35%, L1'-L2'=50%, and R1'-R2'=20%. Therefore, the waiting time is 3 seconds according to B1_W, 6 seconds according to B1_Left, 1 second according to B1_Right, 2 seconds according to B2_W, 4 seconds according to B2_Left, and 1 second according to B2_Right. Therefore, the longest of these (6 seconds in this example) is set as the waiting time.

"Example 4" in FIG. 6(b) shows a case where the duty on the first side and the duty on the second side are both relatively high (high duty case) at 70%. In this way, even if the duties on both sides are both high duty, if the difference between them is substantially none or small, there is substantially none or small difference in expansion and contraction between both sides of the recording medium P. Therefore, the recording medium P does not substantially deform, or the amount of deformation is relatively small, and no waiting time is required. Therefore, in this example, although the duty on the second side is referenced, the difference in duty between both sides is 0%, so no waiting time is required (the waiting time is set to 0 seconds).

"Example 5" in Figure 6 (b) shows a case where the duty on the first side is 0% (blank paper) and the duty on the second side is relatively high at 70% (high duty). In this case, the amount of ink applied to the second side is greater than the amount of ink applied to the first side. Therefore, the recording medium P can be deformed in a similar manner to the case of single-sided printing. Therefore, in this example, no waiting time is required, and since the duty on the first side is 0%, as in "Decision 1" above, no waiting time is required without referring to the duty on the second side (the waiting time is set to 0 seconds).

"Example 6" in FIG. 6(c) shows an example of a configuration that allows Wait to be executed at multiple positions (i.e., multiple Waits) depending on the location where the aforementioned transport malfunction may occur.

Referring again to FIG. 1(a), the handle portion 9 is located at a position relatively far away from the recording head 5. Therefore, when printing on the second side is completed (double-sided printing is completed), the leading edge of the recording medium P has not yet reached the handle portion 9. In such a case, a wait may be executed after printing on the second side is completed.

On the other hand, the transport path switching unit 6 is provided near the downstream side of the recording head 5 in order to reduce the size of the recording device 900 body, and the leading edge of the recording medium P may reach the transport path switching unit 6 before printing on the second side is completed. Therefore, a waiting time must be provided before printing on the second side to prevent transport malfunctions that may occur in the transport path switching unit 6. As a specific example, in a case where the duty on the first side is 70% and the duty on the second side is 0% (i.e., a case similar to "Example 2" in FIG. 6B), the waiting time is 9 seconds according to B1_W, 9 seconds according to B1_Left, 9 seconds according to B1_Right, 6 seconds according to B2_W, 6 seconds according to B2_Left, and 10 seconds according to B2_Right.

In this case, for B2_W (6 seconds), B2_Left (6 seconds), and B2_Right (10 seconds), which correspond to transport problems that may occur in the handhold unit 9, the longest of these, 10 seconds, may be set as the waiting time, and Wait may be executed after printing on the second side is completed. On the other hand, for B1_W (9 seconds), B1_Left (9 seconds), and B1_Right (9 seconds), which correspond to transport problems that may occur in the transport path switching unit 6, the longest of these, 9 seconds, may be set as the waiting time, and Wait may be executed before printing on the second side is completed. Therefore, in this example, the waiting time to prevent transport problems that may occur in the transport path switching unit 6 before printing on the second side may be set to 9 seconds, and the waiting time to prevent transport problems that may occur in the handhold unit 9 after printing on the second side may be set to the remaining 1 second.

The wait position may be selected from positions 1101, 1102, and 1103 (see FIG. 11), but may be another position.

Figure 6 (d) shows another table TB6' for setting the wait time. In the example of Figure 6 (a) described above, the print duty threshold is common regardless of the combination of the location where transport malfunctions may occur, the acquisition range W1, etc. However, as shown in Figure 6 (d), the print duty for executing Wait may be changed for each combination using a combination of the print duty threshold and the wait time as a parameter. According to this aspect, it becomes possible to set the wait time according to the print duty, and it becomes possible to provide various transport controls according to this embodiment in various aspects.

In this example, of the vertical feed conveyance (SEF) and horizontal feed conveyance (LEF), in the case of LEF, which is prone to conveyance malfunction due to deformation of the recording medium (paper) P, Wait is executed. In addition, the ranges W1, L1, and R1 for acquiring the ink application amount are set to one or more areas on the leading end side of the conveyance direction when printing on the second side. This makes it possible to set the Wait time (standby time) according to the degree of conveyance malfunction that may occur. In addition, by adding the information indicating the ink application amount obtained from the above-mentioned areas W1, L1, and R1 and normalizing it by weight addition, it is possible to execute conveyance control to prevent conveyance malfunction in consideration of the tendency of the conveyance malfunction to occur. In addition, by determining whether or not Wait is necessary by referring to the second side duty based on the first side duty when printing on the first side, it is possible to suppress a decrease in throughput when the first side duty is low duty when printing on both sides. In addition, by setting the wait time based on the difference in print duty between the first and second sides, it is possible to set an appropriate wait time when the duty on the first side is higher than the duty on the second side.

(Third Example)
7A shows a table TB7 for carrying out transport control according to the third embodiment. In this example, if the difference in print duty is equal to or greater than a reference value, the transport speed of the recording medium P is reduced and then a wait is executed. Table TB7 is used to set the waiting time and the transport speed in this example.

First, as in the second embodiment described above, when performing double-sided printing, a determination is made as to whether or not to execute a wait when printing on the first side based on the first side duty (Decision 1 (see FIG. 6(a))).

Next, if the first side duty is equal to or greater than the reference value, the second side duty is referenced in addition to the first side duty, and the difference in print duty between the first and second sides is calculated. In this example, if this difference is equal to or greater than the reference value, the transport speed of the recording medium P is reduced, for example, from 15 ips (ips = inches/second) to 5 ips. This makes it possible to delay the time until the leading edge of the recording medium P reaches the location where the aforementioned transport malfunction may occur after printing on the first side. Therefore, the same effect as executing Wait can be obtained.

Figure 7(b) is a diagram for explaining some examples of the selective method of lowering the transport speed and setting the waiting time. Depending on the structure of the recording device 900, lowering the transport speed may be more advantageous in avoiding transport malfunctions than executing Wait. Therefore, by lowering the transport speed, it is possible to obtain the same effect as executing Wait, and to prevent the user from mistaking the temporary suspension of transport for a malfunction.

According to this example, when double-sided printing is performed, if the difference in print duty between the first and second sides is equal to or greater than a reference value, the transport speed is first reduced, and then a wait is executed. This prevents transport problems that may occur during double-sided printing, and makes it possible to suppress unnecessary decreases in throughput during such printing.

(Fourth Example)
8(a) and 8(b) respectively show tables TB8a and TB8b for carrying out transport control according to the fourth embodiment. In this embodiment, in addition to the contents of the other embodiments described above, environmental information indicating the environment such as temperature and humidity, and medium information indicating the type (media type) of the recording medium P are further used. This is because the deformation that may occur when ink is applied to the recording medium P generally differs depending on the environment and media type.

Table TB8a (see FIG. 8(a)) is a correction value table used to refer to environmental information. In the second and third embodiments described above, the ink application amount W1 and L1' and R1' obtained by adding the weights and normalizing L1 and R1 were used to determine whether or not it is necessary to refer to the second surface side duty and to set the standby time. In this example, instead of W1, L1', and R1', W1", L1" and R1" obtained by correcting these with the correction value shown in FIG. 8(a) (referred to as "correction value Env") are used to determine whether or not it is necessary and to set the standby time.

The corrected W1", L1", and R1" are obtained by correcting W1, L1', and R1' as follows:
W1”=W1-Env;
L1″=L1′-Env; and R1″=R1′-Env.

As an example, we will describe the cases where the ink application amount W1 = 50%, the temperature is 25°C and the humidity is 50%, and the temperature is 15°C and the humidity is 10%. In the figure, S indicates temperature and H indicates humidity.

First, the case of "temperature 25°C and humidity 50%" will be described. According to FIG. 8(a), the correction value Env at "temperature 25°C and humidity 50%" is "60". Therefore, W1" (W1 after correction) is obtained by subtracting the correction value Env (=60) from W1 (=50%), and it becomes W1" = 50 - 60 = -10%. In the case of the above-mentioned third embodiment 3 (see FIG. 7(a)), that is, when the correction value Env is not used, a waiting time of 2 seconds is set at a conveying speed of 5 ips for W1 = 50%, whereas in the case of this example, that is, when the correction value Env is used, it becomes W1" = -10%. Therefore, in this example, there is no need to reduce the conveying speed or set a waiting time.

Next, the case of "temperature 15°C and humidity 10%" will be described in the same manner as above. According to FIG. 8(a), the correction value Env at "temperature 15°C and humidity 10%" is "0". Therefore, W1" = 50%, and a waiting time of 2 seconds is set at a transport speed of 5 ips. In the explanation of the above two examples, when W1 = 50%, at "temperature 25°C and humidity 50%" where the deformation of the paper P is relatively small, there is essentially no decrease in throughput during double-sided printing, but at "temperature 15°C and humidity 10%" where the deformation of the paper P is relatively large (transport problems may occur), the throughput during double-sided printing may decrease.

Here, "B1_W" has been described as an example for avoiding transport problems that may occur in the transport path switching unit 6 due to the amount of ink applied W1 at the leading edge of the paper P, but the same can be said for the other "B1_Left" to "B2_Right". Also, in this example, one type of correction value Env is used, but corresponding correction values may be prepared for each of "B1_W" to "B2_Right". Also, the correction values may be set appropriately based on other conditions, for example, they may be set for each print mode (e.g., high quality mode, high speed print mode, etc.) or they may be set based on manual input by the user.

Table TB8a (see FIG. 8(b)) is a table used to set the wait time by referencing the media information. Here, for simplicity of explanation, only "B1_W" is illustrated. In the above-mentioned third embodiment, "B1_W" was not differentiated by media type, but in this embodiment, "B1_W" is further classified by media type, and the print duty threshold and wait time can be set according to the classification. This makes it possible to set an appropriate wait time according to the media type for the same ink application amount, and to avoid unnecessary reduction in throughput when printing on both sides.

For example, considering the case where W1 = 50% and W2 = 0%, according to FIG. 8(b), the conveying speed is reduced to 5 ips, and the waiting times are set to 3 seconds, 8 seconds, 3 seconds, and 0 seconds for plain paper, thin paper, thick paper, and recycled paper, respectively. Therefore, if the above medium information is not referenced, the longest of these (8 seconds) will be set as the waiting time, regardless of the type of recording medium P. However, according to this example, by referencing the medium information, it is possible to set the waiting time according to the media type, and unnecessary decreases in throughput during double-sided printing can be avoided.

Alternatively/as an addendum, the presence or absence (or amount of loading) of the recording medium P in the paper discharge section 8 (see FIG. 1(a)) may be further referenced. As described above, the transport malfunction that may occur in the grip section 9 occurs when the recording medium P is deformed in a manner different from that in the case of single-sided printing due to double-sided printing (curved in the opposite direction from that in the case of single-sided printing). For this reason, when the recording medium P is already loaded on the paper discharge section 8, the grip section 9 is covered by the recording medium P, so transport malfunction does not substantially occur. In other words, while there is a possibility of transport malfunction occurring when printing on the first recording medium P, transport malfunction does not substantially occur when printing on the second or subsequent recording media P. Therefore, when the recording medium P is loaded on the paper discharge section 8, it is not necessary to set a waiting time or reduce the transport speed to avoid transport malfunction that may occur in the grip section 9.

In addition, if one print job instructs printing on multiple recording media P, the second and subsequent recording media P can be stacked on top of the first recording media P that covers the handle section 9. Therefore, for the second and subsequent recording media P, it may be unnecessary to set a waiting time or reduce the conveying speed to avoid possible conveying problems in the handle section 9. This can be achieved with a relatively simple configuration by configuring the recording device 900 to be able to detect whether or not a recording medium P is stacked on the paper discharge section 8; for example, a sensor for detecting the presence or absence of a recording medium P may be provided in the paper discharge section 8.

According to these aspects, transport control can be performed based on environmental information, medium information, the presence or absence of recording medium P in the paper discharge unit 8, and/or whether printing is being performed on the first sheet of recording medium. This makes it possible to further suppress a decrease in throughput during double-sided printing.

According to the above embodiment, when performing double-sided printing, during transport by the transport mechanism after printing on the first side is completed, a wait time based on the difference in print duty between the first and second sides can be executed, and/or the transport speed can be reduced based on this difference. With this configuration, deformation that may occur in the recording medium P is suppressed during transport, and the transport mechanism can continue the transport appropriately. Therefore, according to the embodiment, it is possible to appropriately transport the recording medium P during double-sided printing, without unnecessarily reducing the throughput, and without the need to make structural changes to the recording device 900.

The recording device 900 is not limited to the above-described configuration, and may be modified within the scope of the invention. For example, in the embodiment, the recording head 5 is a line head, but all or part of the contents of the embodiment can be applied to the case where the recording head 5 is a serial head.

(program)
The present invention may be realized by supplying a program for implementing one or more of the functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in a computer of the system or device read and execute the program. For example, the present invention may be realized by a circuit (e.g., an ASIC) for implementing one or more of the functions.

(others)
In the above description, the recording device 900 using the inkjet recording method is taken as an example, but the recording method is not limited to the above. The recording device 900 may be a single-function printer having only a recording function, or a multi-function printer having multiple functions such as a recording function, a FAX function, and a scanner function. The recording device 900 may also be a manufacturing device for manufacturing color filters, electronic devices, optical devices, microstructures, etc., using a predetermined recording method.

In addition, the term "recording (printing)" in this specification should be interpreted broadly. Therefore, the form of "recording" does not matter whether the object formed on the recording medium is significant information such as characters or figures, or whether it is something that is visible to humans and can be perceived visually.

The term "recording medium" should be interpreted broadly, just like the term "recording" above. Therefore, the concept of "recording medium" can include any material capable of receiving ink, such as commonly used paper, cloth, plastic film, metal plate, glass, ceramics, resin, wood, leather, etc.

Furthermore, "ink" should be interpreted broadly, just like "recording" above. Therefore, the concept of "ink" includes not only liquid that is applied to a recording medium to form an image, design, pattern, etc., but also incidental liquid that can be used for processing the recording medium, treating the ink (for example, solidifying or insolubilizing the coloring material in the ink applied to the recording medium), etc. From this perspective, the recording head 5 can also be expressed as a liquid ejection head, and similarly, the recording device 900 can also be expressed as a liquid ejection device.

The invention is not limited to the above-described embodiment, and various modifications and variations are possible without departing from the spirit and scope of the invention. Therefore, the following claims are appended to disclose the scope of the invention.

900: Recording device, P: Recording medium, 5: Recording head, 3-4: Pair of transport rollers, 6: Transport path switching unit, 21: CPU (recording control unit).

Claims (10)

An inkjet recording apparatus capable of double-sided printing,
a recording head capable of recording by applying ink to a first surface and a second surface of a recording medium;
A conveying mechanism for conveying the recording medium;
A recording control unit,
The recording control unit
a first process for acquiring first information indicating an amount of ink applied to a first region on the first surface and second information indicating an amount of ink applied to a second region on the second surface, the second region being located on the opposite side to the first region;
a second process of printing on the first side while transporting the recording medium on a first transport path, and then inverting the recording medium and transporting the recording medium on a second transport path while printing on the second side;
providing a waiting time based on the first information and the second information acquired in the first process when the recording medium is conveyed by the conveying mechanism after the printing on the first side in the second process is completed ;
The inkjet recording apparatus, characterized in that, in the second process, the recording control unit determines whether the second information is necessary based on the first information, and if it is determined that the second information is necessary, sets the waiting time based on the first information and the second information . An inkjet recording apparatus capable of double-sided printing,
a recording head capable of recording by applying ink to a first surface and a second surface of a recording medium;
A conveying mechanism for conveying the recording medium;
A recording control unit,
The recording control unit
a first process for acquiring first information indicating an amount of ink applied to a first region on the first surface and second information indicating an amount of ink applied to a second region on the second surface, the second region being located on the opposite side to the first region;
a second process of printing on the first side while transporting the recording medium on a first transport path, and then inverting the recording medium and transporting the recording medium on a second transport path while printing on the second side;
providing a waiting time based on the first information and the second information acquired in the first process when the recording medium is conveyed by the conveying mechanism after the printing on the first side in the second process is completed;
In the second process, the recording control unit
After the printing on the first side is completed and before the printing on the second side is started, the transport mechanism temporarily stops transporting the sheet and/or reduces a transport speed;
the inkjet recording apparatus further comprising : a stoppage of conveyance by the conveying mechanism and/or a reduction in conveying speed after starting printing on the second side. An inkjet recording apparatus capable of double-sided printing,
a recording head capable of recording by applying ink to a first surface and a second surface of a recording medium;
A conveying mechanism for conveying the recording medium;
A recording control unit,
The recording control unit
a first process for acquiring first information indicating an amount of ink applied to a first region on the first surface and second information indicating an amount of ink applied to a second region on the second surface, the second region being located on the opposite side to the first region;
a second process of printing on the first side while transporting the recording medium on a first transport path, and then inverting the recording medium and transporting the recording medium on a second transport path while printing on the second side;
providing a waiting time based on the first information and the second information acquired in the first process when the recording medium is conveyed by the conveying mechanism after the printing on the first side in the second process is completed;
The inkjet recording apparatus, wherein in the second process, the recording control unit sets the waiting time further based on environmental information and/or medium information. 4. The inkjet recording apparatus according to claim 1, wherein the recording head is a line head. 5. The inkjet recording apparatus according to claim 1, wherein the recording control unit, in the second process, temporarily suspends the transport by the transport mechanism and/or reduces a transport speed based on the waiting time. The inkjet recording apparatus according to claim 1 , wherein the second area is one or more areas on a leading end side in a transport direction when printing is performed on the second surface. A discharge unit that discharges the recording medium is further provided,
The inkjet recording apparatus according to claim 1 , wherein the recording control unit, in the second process, sets the waiting time further based on the presence or absence of the recording medium discharged to the discharge unit. 8. The inkjet recording device according to claim 1, wherein, when the print job instructs printing on a plurality of recording media, the recording control unit, in the second process, sets the waiting time further based on whether printing is to be performed on a first recording medium or not. 1. A method for controlling an inkjet recording device capable of double-sided printing, comprising:
The inkjet recording apparatus includes a recording head capable of recording by applying ink to a first side and a second side of a recording medium, and a transport mechanism that transports the recording medium;
acquiring first information indicating an amount of ink applied to a first region on the first surface, and second information indicating an amount of ink applied to a second region on the second surface, the second region being located on the opposite side of the first region;
printing on the first side while transporting the recording medium on a first transport path, and then inverting the recording medium and transporting the recording medium on a second transport path while printing on the second side;
providing a waiting time based on the first information and the second information when the recording medium is conveyed by the conveying mechanism after the printing on the first side is completed ;
The method according to claim 1, wherein in the printing step, it is determined whether the second information is necessary based on the first information, and if it is determined that the second information is necessary, the waiting time is set based on the first information and the second information . The method according to claim 9, characterized in that, when the transport mechanism transports the recording medium after printing on the first side is completed, the transport mechanism temporarily stops transporting the recording medium and/or reduces the transport speed based on the waiting time .

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