JP2021172081A - Flushing timing adjustment method and ink jet recording device - Google Patents

Abstract

To accurately perform flushing by properly adjusting flushing timing without forming an opening into an excessively large size in oder to reduce influence of a tolerance of an opening detection sensor.SOLUTION: In a flushing timing adjustment method, at a plurality of discharge timings which are preset with reference to a detection time point of a recording medium by a recording medium detection sensor, ink is discharged from a prescribed nozzle of a recording head, thereby recording a first chart on the recording medium. Also, at a plurality of discharge timings which are preset with reference to a detection time point of the recording medium by the opening detection sensor, ink is discharged from another nozzle of the recording head, thereby recording a second chart on the recording medium side by side with the first chart. On the basis of an instruction input after recording of the first and second charts on the recording medium, a flushing timing which is set with reference to a detection time point of the opening by the opening detection sensor is adjusted.SELECTED DRAWING: Figure 13

Description

The present invention relates to a flushing timing adjusting method in an inkjet recording device and the inkjet recording device thereof.

When a quick-drying ink is used in an inkjet recording device such as an inkjet printer, the nozzle of the recording head is likely to be clogged due to the thickening due to the drying of the ink. Therefore, before printing on paper, it is necessary to eject and discard the thickened ink. The ink ejection operation that does not contribute to the formation of an image on paper is also referred to as flushing (empty ejection) here.

Conventionally, techniques for flushing are disclosed in, for example, Patent Documents 1 to 3. In Patent Document 1, flushing is performed by ejecting ink from a recording head between papers supplied to a transport belt (so-called paper-to-paper) and passing the ink through an opening provided in the transport belt. I am trying to do it. The position of the opening of the transport belt is detected by the opening detection sensor, and the ink ejection in flushing is controlled based on the detection result.

Patent Document 2 discloses a technique for correcting the ink ejection timing with respect to the opening in consideration of the influence of the fluctuation of the pitch of the opening in the paper transport direction due to the peripheral length tolerance of the transport belt and the like. ..

Further, for example, when the paper is placed on the transport belt so as to overlap the opening, the paper is bent and the distance (gap) between the recording head and the paper becomes non-uniform. Therefore, there is a concern that the quality of the image recorded on the paper will deteriorate. In Patent Document 3, by supplying the paper to the transport belt so as not to overlap the opening, the deterioration of the quality of the recorded image due to the bending of the paper is suppressed.

Japanese Unexamined Patent Publication No. 2001-113690 Japanese Unexamined Patent Publication No. 2012-45867 Japanese Unexamined Patent Publication No. 2006-21399

By the way, the opening detection sensor has a detection tolerance (variation in detection accuracy) and also has a tolerance in installation position (variation in installation position). Even if the device is designed with the center value of each tolerance, if each tolerance is accumulated, the variation in the ink ejection timing (flushing timing) at the time of flushing between the devices becomes large. In order to easily cope with such variations in flushing timing, for example, a method of forming a large opening provided in the transport belt can be considered. However, if the opening is formed large, the strength of the transport belt may decrease, leading to tearing of the transport belt. Further, as mentioned in Patent Document 3, forming a large opening leads to a decrease in print quality due to a change in the gap due to bending of the paper overlapping the opening. Therefore, it is preferable to make the opening as small as possible.

Therefore, the ink discharged from the recording head during flushing can pass through the opening accurately without forming the opening larger than necessary in order to reduce the influence of the tolerance of the opening detection sensor. In addition, it is necessary to appropriately adjust the flushing timing for each device. However, no such adjustment of flushing timing has been proposed so far.

In view of the above problems, in order to reduce the influence of the tolerance of the opening detection sensor, the present invention appropriately adjusts the flushing timing and accurately performs flushing without forming the opening larger than necessary. It is an object of the present invention to provide a flushing timing adjusting method capable of adjusting the flushing timing and an inkjet recording apparatus capable of adjusting such a flushing timing.

The flushing timing adjusting method in the inkjet recording apparatus according to one aspect of the present invention is the flushing timing which is the ejection timing of the ink when flushing the ink is ejected from the recording head toward the opening of the endless conveyor belt. Is a way to adjust. In the above adjustment method, the recording medium supplied from the recording medium supply unit to the transport belt is detected by the recording medium detection sensor, and the opening detection sensor that detects the opening that moves due to the traveling of the transport belt is used for the transport. The recording medium conveyed by the belt is detected, and ink is ejected from a predetermined nozzle of the recording head at a plurality of ejection timings preset with reference to the detection time of the recording medium by the recording medium detection sensor. The first chart is recorded on the recording medium, and ink is ejected from another nozzle of the recording head at a plurality of ejection timings preset with reference to the detection time of the recording medium by the opening detection sensor. By discharging, the second chart is recorded on the recording medium side by side with the first chart, and based on the instruction input after recording the first chart and the second chart on the recording medium. , The flushing timing set with reference to the detection time of the opening by the opening detection sensor is adjusted.

The inkjet recording apparatus according to another aspect of the present invention conveys a recording head having a plurality of nozzles for ejecting ink and a recording medium, and the ink is transmitted at a timing different from the timing at which the recording head contributes to image formation. An endless transport belt having openings for passing the ink at a plurality of locations in the transport direction of the recording medium when flushing is executed, and a recording medium supply that supplies the recording medium to the transport belt. A recording medium detection sensor that detects a recording medium supplied from the recording medium supply unit to the transport belt, and an opening that moves as the transport belt travels, and on the transport belt. It includes an opening detection sensor that detects the recording medium, and an ejection control unit that controls ejection of the ink from the recording head. The ejection control unit ejects ink from a predetermined nozzle of the recording head to the recording medium at a plurality of ejection timings set in advance with reference to the detection time of the recording medium by the recording medium detection sensor. The first chart is recorded, and ink is ejected from another nozzle of the recording head at a plurality of ejection timings preset with reference to the detection time of the recording medium by the opening detection sensor. The second chart is recorded on the recording medium side by side with the first chart.

Based on the instruction input after recording the first chart and the second chart on the recording medium, the flushing timing set with reference to the detection time of the opening by the opening detection sensor is adjusted. As a result, even if there is a tolerance (detection tolerance, installation position tolerance) in the opening detection sensor, when flushing is performed when the device is used by the user, ink is ejected from the recording head at a pre-adjusted flushing timing. It is possible to pass through the opening of the transport belt. Therefore, in order to reduce the influence of the above tolerance, flushing can be performed accurately without forming the opening larger than necessary. Further, it is possible to realize an inkjet recording apparatus capable of adjusting such flushing timing.

It is explanatory drawing which shows the schematic structure of the printer as the inkjet recording apparatus which concerns on one Embodiment of this invention. It is a top view of the recording part provided in the said printer. It is explanatory drawing which shows typically the structure around the paper transport path from the paper feed cassette of the printer to the 2nd transport unit through the 1st transport unit. It is a block diagram which shows the hardware composition of the main part of the said printer. It is a top view which shows one structural example of the 1st transfer belt which the 1st transfer unit has. It is explanatory drawing which shows typically an example of the pattern of the opening group for flushing when the 1st transport belt of FIG. 5 is used, and the paper which is arranged on the 1st transport belt according to the said pattern. be. It is explanatory drawing which shows the other example of the said pattern, and the paper which is arranged on the said 1st transport belt according to the said pattern schematically. It is explanatory drawing which shows still another example of the said pattern, and the paper which is arranged on the said 1st transport belt according to the said pattern. It is explanatory drawing which shows still another example of the said pattern, and the paper which is arranged on the said 1st transport belt according to the said pattern. It is explanatory drawing which shows typically the light amount distribution of the reflected light when the object is irradiated with light. It is sectional drawing which shows the schematic structure of the opening detection sensor provided in the said printer. It is explanatory drawing which shows typically the variation of the signal output from the said opening detection sensor. It is a flowchart which shows the flow of operation by the adjustment method of a flushing timing. 6 is a timing chart showing an example of output signals of various sensors and various timings when paper is supplied on the first transport belt. It is explanatory drawing which shows typically an example of the 1st chart and the 2nd chart recorded on the paper when the said adjustment method is carried out. It is explanatory drawing which shows typically the state which the position | displacement occurred in the 1st chart and the 2nd chart of the structure shown in FIG. It is explanatory drawing which shows typically the other example of the said 1st chart and the said 2nd chart. It is explanatory drawing which shows typically the state which the position | displacement occurred in the 1st chart and the 2nd chart of the structure shown in FIG. It is a timing chart which shows at least the flushing execution timing for each opening of the two opening rows belonging to each opening group of the 1st transport belt.

[1. Inkjet recording device configuration]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing a schematic configuration of a printer 100 as an inkjet recording device according to an embodiment of the present invention. The printer 100 includes a paper feed cassette 2 which is a paper storage unit. The paper cassette 2 is arranged below the inside of the printer main body 1. Paper P, which is an example of a recording medium, is housed inside the paper cassette 2.

The paper feed device 3 is arranged on the downstream side of the paper feed cassette 2 in the paper transport direction, that is, above the right side of the paper feed cassette 2 in FIG. By the paper feeding device 3, the paper P is separated and sent out one by one toward the upper right side of the paper feed cassette 2 in FIG.

The printer 100 includes a first paper transport path 4a inside. The first paper transport path 4a is located on the upper right side of the paper feed cassette 2 in the paper feed direction. The paper P sent out from the paper feed cassette 2 is vertically upwardly conveyed along the side surface of the printer main body 1 by the first paper conveying path 4a.

A resist roller pair 13 is provided at the downstream end of the first paper transport path 4a in the paper transport direction. Further, the first transport unit 5 and the recording unit 9 are arranged in the immediate vicinity of the resist roller pair 13 on the downstream side in the paper transport direction. The paper P sent out from the paper feed cassette 2 reaches the resist roller pair 13 through the first paper transport path 4a. The resist roller pair 13 measures the timing of the ink ejection operation executed by the recording unit 9 while correcting the diagonal feed of the paper P, and the paper is directed toward the first transport unit 5 (particularly, the first transport belt 8 described later). Send out P. That is, the resist roller pair 13 constitutes a recording medium supply unit that supplies the paper P on the first transport belt 8.

The paper P fed to the first transport unit 5 by the resist roller pair 13 is transported by the first transport belt 8 to a position facing the recording unit 9 (particularly, the recording heads 17a to 17c described later). An image is recorded on the paper P by ejecting ink from the recording unit 9 onto the paper P. At this time, the ink ejection in the recording unit 9 is controlled by the control device 110 inside the printer 100.

In the paper transport direction, the second transport unit 12 is arranged on the downstream side (left side in FIG. 1) of the first transport unit 5. The paper P on which the image is recorded by the recording unit 9 is sent to the second transport unit 12. The ink ejected onto the surface of the paper P is dried while passing through the second transport unit 12.

In the paper transport direction, a decaler portion 14 is provided on the downstream side of the second transport unit 12 and near the left side surface of the printer main body 1. The paper P whose ink has been dried by the second transport unit 12 is sent to the decaler unit 14, and the curl generated on the paper P is corrected.

A second paper transport path 4b is provided on the downstream side (upper side of FIG. 1) of the decaler portion 14 in the paper transport direction. When double-sided recording is not performed, the paper P that has passed through the decaler portion 14 passes through the second paper transport path 4b and is discharged to the paper ejection tray 15 provided outside the left side surface of the printer 100.

An inversion transport path 16 for double-sided recording is provided above the recording unit 9 and the second transport unit 12 in the upper part of the printer main body 1. When double-sided recording is performed, the paper P that has passed through the second transport unit 12 and the decaler section 14 after the recording on one side (first side) of the paper P is completed is reversed through the second paper transport path 4b. It is sent to the transport path 16.

The paper P sent to the reverse transport path 16 is subsequently switched in the transport direction for recording on the other side (second side) of the paper P. Then, the paper P passes through the upper part of the printer main body 1 and is fed toward the right side, and is fed to the first transport unit 5 again in a state where the second side is facing upward through the resist roller pair 13. In the first transfer unit 5, the paper P is conveyed to a position facing the recording unit 9, and an image is recorded on the second surface by ejecting ink from the recording unit 9. The paper P after double-sided recording is discharged to the paper discharge tray 15 via the second transport unit 12, the decaler section 14, and the second paper transport path 4b in this order.

Further, a maintenance unit 19 and a cap unit 20 are arranged below the second transport unit 12. The maintenance unit 19 moves horizontally below the recording unit 9 when executing purging, wipes the ink extruded from the ink ejection port of the recording head, and collects the wiped ink. Note that purging refers to an operation of forcibly pushing out ink from the ink ejection port of the recording head in order to eject thickened ink, foreign matter, and air bubbles in the ink ejection port. The cap unit 20 moves horizontally below the recording unit 9 when capping the ink ejection surface of the recording head, and further moves upward and is mounted on the lower surface of the recording head.

FIG. 2 is a plan view of the recording unit 9. The recording unit 9 includes a head housing 10 and line heads 11Y, 11M, 11C, and 11K. The line heads 11Y to 11K have a predetermined interval (for example,) with respect to the transport surface of the endless first transport belt 8 stretched on a plurality of rollers including the drive roller 6a, the driven roller 6b, and the tension rollers 7a and 7b. It is held by the head housing 10 at a height at which 1 mm) is formed. The drive roller 6a causes the first transport belt 8 to travel in the transport direction (arrow A direction) of the paper P. The drive of the drive roller 6a is controlled by the main control unit 110c (see FIG. 4) of the control device 110. The plurality of rollers are arranged in the order of the tension roller 7a, the tension roller 7b, the driven roller 6b, and the driving roller 6a along the traveling direction of the first transport belt 8.

The line heads 11Y to 11K each have a plurality of (here, three) recording heads 17a to 17c. The recording heads 17a to 17c are arranged in a staggered manner along the paper width direction (arrow BB'direction) orthogonal to the paper transport direction (arrow A direction). The recording heads 17a to 17c have a plurality of ink ejection ports 18 (nozzles). The ink ejection ports 18 are arranged side by side at equal intervals in the width direction of the recording head, that is, in the paper width direction (arrow BB'direction). From the line heads 11Y to 11K, inks of each color of yellow (Y), magenta (M), cyan (C), and black (K) are first conveyed through the ink ejection ports 18 of the recording heads 17a to 17c. The ink is ejected toward the paper P conveyed by the belt 8.

FIG. 3 schematically shows the configuration around the transport path of the paper P from the paper feed cassette 2 to the second transport unit 12 via the first transport unit 5. Further, FIG. 4 is a block diagram showing a hardware configuration of a main part of the printer 100. In addition to the above configuration, the printer 100 further includes a resist sensor 21, a paper detection sensor 22, an opening detection sensor 23, and a belt sensor 24.

The resist sensor 21 detects the paper P that is conveyed from the paper cassette 2 by the paper feeding device 3 and sent to the resist roller pair 13. The resist sensor 21 is located on the upstream side of the resist roller pair 13 in the supply direction of the paper P. The paper supply control unit 110b, which will be described later, of the control device 110 can control the rotation start timing of the resist roller pair 13 based on the detection result of the resist sensor 21. For example, the paper supply control unit 110b can control the supply timing of the paper P to the first transport belt 8 after skew (skew) correction by the resist roller pair 13 based on the detection result of the resist sensor 21. ..

The paper detection sensor 22 is a recording medium detection sensor that detects the passage (timing) of the tip of the paper P supplied from the resist roller pair 13 to the first transport belt 8. The paper detection sensor 22 is located upstream of the opening detection sensor 23 in the paper transport direction. The ejection control unit 110a receives ink for the paper P that reaches a position facing the line heads 11Y to 11K (recording heads 17a to 17c) by the first conveyor belt 8 based on the detection result of the paper P by the paper detection sensor 22. The discharge timing can be controlled.

The opening detection sensor 23 detects an opening 80 (see FIG. 5) provided on the first transport belt 8 to be described later. The opening detection sensor 23 is located on the upstream side of the recording unit 9 and on the downstream side of the paper detection sensor 22 in the paper transport direction (traveling direction of the first transport belt 8). The ejection control unit 110a controls the recording heads 17a to 17c based on the detection result of the opening 80 by the opening detection sensor 23, and can eject ink at a predetermined timing at the time of flushing described later.

The belt sensor 24 detects the position of the opening group 82, which is a reference when the paper is conveyed, among the plurality of opening groups 82 (openings 80) in the first conveying belt 8. For example, in the first transport belt 8, a marker is provided at a position corresponding to the reference opening group 82, and the belt sensor 24 detects the marker to detect the reference opening group 82. Can be done.

The belt sensor 24 is located upstream of the driven roller 6b on which the first transport belt 8 is stretched in the paper transport direction (traveling direction of the first transport belt 8) in the paper transport direction. Therefore, the belt sensor 24 may be located between the driven roller 6b and the other roller 7b, or may be located between the roller 7a and the roller 7b. The driven roller 6b is located on the upstream side of the first transport belt 8 in the traveling direction with respect to the recording unit 9. The paper supply control unit 110b controls the resist roller pair 13 so as to supply the paper P to the first transport belt 8 at a predetermined timing based on the detection result of the opening group 82 by the belt sensor 24. be able to.

The paper detection sensor 22, the opening detection sensor 23, and the belt sensor 24 described above can be composed of a transmissive or reflective optical sensor, a CIS sensor (Contact Image Sensor, a close contact image sensor), and the like. In particular, the opening detection sensor 23 is preferably composed of an optical sensor that detects specularly reflected light and diffusely reflected light, and the reason will be described later.

In addition, the printer 100 may be provided with a meandering detection sensor that detects the meandering of the first conveying belt 8, and may be configured to correct the meandering of the first conveying belt 8 based on the detection result.

Further, the printer 100 further includes an operation panel 27, a storage unit 28, and a communication unit 29.

The operation panel 27 is an operation unit for receiving various setting inputs. For example, the user can operate the operation panel 27 to input information on the size of the paper P to be set in the paper feed cassette 2, that is, the size of the paper P to be conveyed by the first transfer belt 8. The user can also operate the operation panel 27 to input the number of sheets of paper P to be printed or to instruct the start of the print job.

The storage unit 28 is a memory that stores the operation program of the control device 110 and various information, and includes a ROM (Read Only Memory), a RAM (Random Access Memory), a non-volatile memory, and the like. There is. The information set by the operation panel 27 (for example, the size information of the paper P) is stored in the storage unit 28. Further, the storage unit 28 also stores information on the position of each opening 80 of the first transport belt 8 and information on the pattern of the opening 80 through which ink is passed during flushing, which will be described later.

The communication unit 29 is a communication interface for transmitting and receiving information to and from an external device (for example, a personal computer (PC)). For example, when the user operates a PC and sends a print command to the printer 100 together with the image data, the above image data and the print command are input to the printer 100 via the communication unit 29. In the printer 100, the ejection control unit 110a controls the recording heads 17a to 17c based on the image data to eject ink, so that an image can be recorded on the paper P.

From the above, it can be said that the operation panel 27 and the communication unit 29 described above function as an input reception unit 30 that receives input of various information.

Further, the printer 100 of this embodiment includes a control device 110. The control device 110 is composed of, for example, a CPU (Central Processing Unit), and includes a discharge control unit 110a, a paper supply control unit 110b, and a main control unit 110c. The ejection control unit 110a controls the ejection of ink in the recording heads 17a to 17c. The paper supply control unit 110b controls the resist roller pair 13 as the recording medium supply unit based on the detection result of the opening group 82 by the belt sensor 24, and controls the paper P supply by the resist roller pair 13. It is a recording medium supply control unit. The main control unit 110c controls the operation of each unit inside the printer 100. The ejection control unit 110a, the paper supply control unit 110b, and the main control unit 110c may further have functions as a calculation unit for performing necessary calculations and a timekeeping unit for timing the time.

Further, as shown in FIG. 3, the printer 100 has ink receiving portions 31Y, 31M, 31C, and 31K on the inner peripheral surface side of the first transport belt 8. When flushing is executed by the recording heads 17a to 17c, the ink receiving portions 31Y to 31K receive and collect the ink discharged from the recording heads 17a to 17c and passed through the opening 80 of the first transport belt 8. Therefore, the ink receiving portions 31Y to 31K are provided at positions facing the recording heads 17a to 17c of the line heads 11Y to 11K via the first transport belt 8. The ink collected by the ink receiving units 31Y to 31K is sent to, for example, a waste ink tank and discarded, but the ink may be reused without being discarded.

Here, flushing is from the ink ejection port 18 at a timing different from the timing that contributes to image formation (image recording) on the paper P for the purpose of reducing or preventing clogging of the ink ejection port 18 due to ink drying. It refers to ejecting ink. The execution of flushing in the recording heads 17a to 17c is controlled by the discharge control unit 110a.

The second transport unit 12 described above includes a second transport belt 12a and a dryer 12b. The second transport belt 12a is stretched by two driving rollers 12c and a driven roller 12d. The paper P conveyed by the first transfer unit 5 and whose image is recorded by ink ejection by the recording unit 9 is conveyed by the second transfer belt 12a, dried by the dryer 12b during transfer, and transferred to the decaler unit 14 described above. Be transported.

[2. Details of the first transport belt]
(2-1. Example of configuration of the first transport belt)
Next, the details of the first transport belt 8 of the first transport unit 5 will be described. FIG. 5 is a plan view showing a configuration example of the first transport belt 8. In this embodiment, a negative pressure suction method is adopted in which the paper P is attracted to the first transport belt 8 by negative pressure suction and transported. Therefore, the first transport belt 8 is provided with innumerable suction holes 8a through which the suction air generated by the negative pressure suction passes.

Further, the first transport belt 8 is also provided with an opening group 82. The opening group 82 is a set of openings 80 through which ink discharged from each nozzle (ink ejection port 18) of the recording heads 17a to 17c is passed during flushing. The opening area of one opening 80 is larger than the opening area of one suction hole 8a. The first transport belt 8 has a plurality of opening groups 82 in the transport direction (A direction) of the paper P in one cycle, and the present embodiment has six. Note that one cycle refers to a period during which the first transport belt 8 makes one revolution. When the opening groups 82 are distinguished from each other, the six opening groups 82 are referred to as opening groups 82A to 82F from the downstream side in the A direction. The suction hole 8a is located between the opening group 82 and the opening group 82 that are adjacent to each other in the A direction. That is, in the first transport belt 8, the suction hole 8a is not formed in the region overlapping the opening group 82 (around the opening 80).

The opening group 82 is irregularly located in the A direction in one cycle of the first transport belt 8. That is, in the A direction, the distance between the adjacent opening group 82 and the opening group 82 is not constant but different. At this time, the maximum distance between the two opening groups 82 adjacent to each other in the A direction (for example, the distance between the opening group 82A and the opening group 82B in FIG. 5) is the minimum printable size (for example, A4 size (horizontal placement)). ) Is longer than the length of the paper P in the A direction when it is placed on the first transport belt 8.

The opening group 82 has an opening row 81. The opening row 81 is configured by arranging a plurality of openings 80 in the belt width direction (paper width direction, BB'direction) orthogonal to the A direction. One opening group 82 has at least one opening row 81 in the A direction, and in the present embodiment, has two rows of opening rows 81. When distinguishing the two rows of openings 81 from each other, one is referred to as the opening row 81a and the other is referred to as the opening row 81b.

In one opening group 82, the opening 80 of any opening row 81 (eg, opening row 81a) is in the BB'direction with the opening 80 of the other opening row 81 (eg, opening row 81b). It is positioned so as to be offset and overlap with a part of the opening 80 of another opening row 81 (for example, opening row 81b) when viewed in the A direction. Further, in each opening row 81, the plurality of openings 80 are located at equal intervals in the BB'direction.

By arranging the plurality of opening rows 81 in the A direction to form one opening group 82 as described above, the width of the opening group 82 in the BB'direction is the BB' direction of the recording heads 17a to 17c. It is larger than the width of. Therefore, the opening group 82 covers the entire ink ejection region of the recording heads 17a to 17c in the BB'direction, and the ink ejected from all the ink ejection ports 18 of the recording heads 17a to 17c during flushing is opened. It passes through any opening 80 of the group 82.

From the above, the first transport belt 8 has a plurality of opening groups 82 including openings 80 through which the ink discharged by the recording heads 17a to 17c passes during flushing at different intervals in the A direction, which is the transport direction. It can be said that it has a place.

(2-2. About the pattern of the opening group used for flushing)
In the present embodiment, the ejection control unit 110a controls the recording heads 17a to 17c based on the image data transmitted from the outside (for example, a PC) while conveying the paper P using the first conveying belt 8. As a result, the image is recorded on the paper P. At that time, clogging of the ink ejection port 18 is reduced or prevented by causing the recording heads 17a to 17c to perform flushing (flushing between papers) between the conveyed paper P and the paper P. ..

Here, in the present embodiment, the discharge control unit 110a uses a pattern (combination) in the A direction of a plurality of opening groups 82 used for flushing in one cycle of the first transport belt 8 and is the size of the paper P. Determined according to. The size of the paper P to be used is based on the information stored in the storage unit 28 by the ejection control unit 110a (size information of the paper P input by the operation panel 27a) or the image data transmitted from the outside together with the print command. Can be recognized. The pattern of the opening group 82 is literally distinguished from the placement pattern of the paper P, which will be described later.

6 to 9 show an example of a pattern of the opening group 82 for each paper P having a different size. For example, when the paper P to be used is A4 size (horizontal placement) or letter size (horizontal placement), the ejection control unit 110a selects the pattern of the opening group 82 shown in FIG. That is, the discharge control unit 110a selects the opening groups 82A, 82C, and 82F as the opening group 82 used for flushing from the six opening groups 82 shown in FIG. When the paper P to be used is A4 size (vertical installation) or letter size (vertical installation), the ejection control unit 110a has, as shown in FIG. 7, among the six opening groups 82, the opening group used for flushing. As 82, the opening groups 82A and 82D are selected. When the paper P to be used is A3 size, B4 size or legal size (all vertically installed), the ejection control unit 110a has an opening used for flushing from among the six opening groups 82 as shown in FIG. As the group 82, the opening groups 82A, 82B, 82E are selected. When the paper P to be used has a size of 13 inches × 19.2 inches, as shown in FIG. 9, the ejection control unit 110a opens as the opening group 82 used for flushing from the six opening groups 82. Select groups 82A and 82D. In each drawing, the opening 80 of the opening group 82 belonging to the above pattern is shown in black for convenience.

Then, the discharge control unit 110a causes the recording heads 17a to 17c to perform flushing at the timing when the opening group 82 located in the determined pattern faces the recording heads 17a to 17c by the traveling of the first transport belt 8. Here, the traveling speed (paper transport speed) of the first transport belt 8 and the positional relationship between the recording heads 17a to 17c and the opening detection sensor 23 with respect to the first transport belt 8 are all known. Therefore, when the opening detection sensor 23 detects that the opening 80 of the predetermined opening group 82 has passed by the traveling of the first transport belt 8, the predetermined opening group 82 records the number of seconds after the detection time. It can be seen whether or not the heads pass through the positions facing the heads 17a to 17c. Therefore, the ejection control unit 110a ejects ink from the recording heads 17a to 17c at the ejection timing determined based on the detection result of the opening 80 by the opening detection sensor 23, so that the openings are located in the pattern determined above. The recording heads 17a to 17c can be flushed so that the ink passes through the opening 80 of the group 82.

(2-3. Paper placement pattern)
The paper supply control unit 110b controls the supply of the paper P to the first transport belt 8 by the resist roller pair 13 so as to deviate in the A direction from the opening group 82 located in the pattern determined above. That is, the paper supply control unit 110b supplies the paper P by the resist roller pair 13 between the plurality of opening groups 82 arranged in the A direction in the above pattern on the first transport belt 8.

For example, when the paper P to be used is A4 size (horizontal placement) or letter size (horizontal placement), the paper supply control unit 110b has an opening group 82A on the first transport belt 8 as shown in FIG. Two sheets of paper P are arranged between the opening group 82C and two sheets of paper P are arranged between the opening group 82C and the opening group 82F, and the opening group 82F and the opening of the next cycle are arranged. The resist roller pair 13 is controlled to supply the paper P to the first transport belt 8 at a predetermined supply timing so that one sheet P is arranged between the group 82A and the group 82A. At this time, the paper supply control unit 110b is separated from the opening groups 82A, 82C, 82F located in the above pattern on the first transport belt 8 in the A direction (including both the upstream side and the downstream side) by a predetermined distance or more. The resist roller pair 13 is controlled to supply the paper P to the first transport belt 8 so that the paper P is arranged at the vertical position. The predetermined distance is set to 10 mm as an example here.

Here, the supply timing of the paper P by the resist roller pair 13 can be determined by the paper supply control unit 110b based on the detection result of the predetermined opening group 82 by the belt sensor 24. For example, when the belt sensor 24 detects that the reference opening group 82 (for example, the opening group 82A) has passed due to the traveling of the first transport belt 8, the paper supply control unit 110b registers several seconds after the detection time. If the paper P is supplied to the first transport belt 8 by the roller pair 13, it can be determined whether the paper P can be arranged at each position shown in FIG. Therefore, the paper supply control unit 110b determines the supply timing of the paper P based on the detection result of the opening group 82 by the belt sensor 24, and the resist roller pair 13 is supplied so that the paper P is supplied at the determined supply timing. To control. As a result, the paper P can be arranged at each position shown in FIG. 6 on the first transport belt 8 at approximately equal intervals. In the example of FIG. 6, five sheets of paper P can be conveyed in one cycle of the first conveying belt 8, and 150 ipm (images per minute) is realized as the number of prints (productivity) per minute of the paper P. be able to.

When the paper P to be used is A4 size (vertical installation) or letter size (vertical installation), the paper supply control unit 110b has an opening group 82A and an opening on the first transport belt 8 as shown in FIG. The resist roller pair 13 is controlled so that two sheets of paper P are arranged between the group 82D and two sheets of paper P are arranged between the opening group 82D and the opening group 82A of the next cycle. Then, the paper P is supplied to the first transport belt 8 at a predetermined supply timing. In the example of FIG. 7, four sheets of paper P can be conveyed in one cycle of the first conveying belt 8, and a productivity of 120 ipm can be realized.

When the paper P to be used is A3 size, B4 size or legal size (all vertically installed), the paper supply control unit 110b opens the opening group 82A and the opening on the first transport belt 8 as shown in FIG. One sheet of paper P is arranged between the part group 82B, one sheet of paper P is arranged between the opening group 82B and the opening group 82E, and the opening group 82E and the opening group of the next cycle are arranged. The resist roller pair 13 is controlled to supply the paper P to the first transport belt 8 at a predetermined supply timing so that one sheet P is arranged between the paper P and the 82A. In the example of FIG. 8, three sheets of paper P can be conveyed in one cycle of the first conveying belt 8, and a productivity of 90 ipm can be realized.

When the paper P to be used has a size of 13 inches × 19.2 inches, the paper supply control unit 110b has the opening group 82A and the opening group 82D on the first transport belt 8 as shown in FIG. A predetermined number of sheets P are controlled by controlling the resist roller pair 13 so that one sheet of paper P is arranged between them and one sheet of paper P is arranged between the opening group 82D and the opening group 82A of the next cycle. Paper P is supplied to the first transport belt 8 at the supply timing. In the example of FIG. 9, two sheets of paper P can be conveyed in one cycle of the first conveying belt 8, and a productivity of 60 ipm can be realized.

That is, as shown in FIGS. 6 to 9, the pattern of the opening group 82 used for flushing is determined according to the size of the paper P used, and thereby the paper located offset from the opening group 82 in the A direction. The placement pattern of P is determined. From this, it can be said that the placement pattern of the paper P mounted on the first transport belt 8 is determined according to the size of the paper P to be used.

Here, the supply speed of the paper P (running speed of the first transport belt 8), the relative positional relationship between the recording heads 17a to 17c and the paper detection sensor 22 is known. Therefore, when the paper detection sensor 22 detects the passage of the paper P, it is possible to know how many seconds after the detection time the paper P passes the position facing the recording heads 17a to 17c. Therefore, the ejection control unit 110a ejects ink from the recording heads 17a to 17c at the ejection timing determined based on the detection result of the paper P by the paper detection sensor 22, so that the ink ejected from the recording heads 17a to 17c is ejected. The image can be recorded on the paper P by landing on the paper P.

(3. Adjustment of flushing timing)
During normal printing, as described in (2-3) above, the ejection control unit 110a starts from the recording heads 17a to 17c at the first ejection timing determined based on the time when the paper P is detected by the paper detection sensor 22. Ink is ejected. Here, the first ejection timing is defined as, for example, a time when T1 time (unit: seconds) has elapsed from the time when the paper P is detected by the paper detection sensor 22. On the other hand, when flushing is executed, as described in (2-2) above, the discharge control unit 110a records at the second discharge timing determined based on the detection time of the opening 80 by the opening detection sensor 23. Ink is ejected from the heads 17a to 17c. Here, the second ejection timing is defined as, for example, a time when T2 hours (unit: seconds) have elapsed from the time when the paper P is detected by the opening detection sensor 23. Since the paper detection sensor 22 is located upstream of the opening detection sensor 23 with respect to the recording heads 17a to 17c (recording unit 9), T1> T2.

The above-mentioned second ejection timing varies from device to device (printer 100) depending on the detection tolerance and the installation tolerance of the opening detection sensor 23. In this embodiment, in order to easily deal with such variations in the second discharge timing for each device, the second discharge timing is adjusted for each device by the method described later. Here, before explaining the second discharge timing, that is, the adjustment of the flushing timing, the details of the above-mentioned opening detection sensor 23 used for the adjustment of the flushing timing will be described first.

(3-1. Details of the opening detection sensor)
In the present embodiment, as the opening detection sensor 23, an optical analog sensor (optical sensor) that detects specular reflected light and diffuse reflected light is used. In addition, such an optical sensor is also called an image density sensor (ID sensor). FIG. 10 schematically shows the light amount distribution of reflected light (specular reflected light, diffusely reflected light) when the object is irradiated with light. As shown in the figure, when an object is irradiated with light, the light is reflected on the surface of the object. When the angle is constant, it is determined according to the characteristics of the object (for example, the refractive index). The ID sensor is usually used as a sensor for detecting the state of the detection target (for example, image density) by utilizing the fact that the light amount distribution of the reflected light changes according to the characteristics of the object.

FIG. 11 is a cross-sectional view showing a schematic configuration of the opening detection sensor 23. The opening detection sensor 23 includes, for example, a light source 23a made of an LED, a first light receiving unit 23b for detecting specularly reflected light, and a second light receiving unit 23c for detecting diffuse reflected light in the housing 23d. It is composed of. The first light receiving unit 23b and the second light receiving unit 23c are composed of, for example, a photodiode. The light emitted from the light source 23a passes through the lens 23e provided in the housing 23d and is applied to the first transport belt 8. Then, of the light reflected by the first transport belt 8, the specularly reflected light passes through the lens 23e again and is received by the first light receiving unit 23b. Therefore, a signal corresponding to the intensity of the specularly reflected light is output from the first light receiving unit 23b. On the other hand, of the light reflected by the first transport belt 8, the diffusely reflected light passes through the lens 23e again and is received by the second light receiving unit 23c. Therefore, a signal corresponding to the intensity of the diffuse reflected light is output from the second light receiving unit 23c.

FIG. 12 schematically shows a variation of the signal output from the opening detection sensor 23. In FIG. 12, the signal output from the first light receiving unit 23b is referred to as “output 1”, and the signal output from the second light receiving unit 23c is referred to as “output 2”.

As shown in the figure on the left side of FIG. 12, when the object is the first transport belt 8, the level (strength) of the output 1 is relatively high, and the level of the output 2 is relatively low. Further, as shown in the central figure of FIG. 12, when the light enters the opening 80 of the first transport belt 8, the light passes through the opening 80, so that the level of the output 1 and the level of the output 2 are different. Both are low.

On the other hand, as shown in the figure on the right side of FIG. 12, when the light is incident on the paper P on the first transport belt 8, the degree of diffusion of the incident light is higher than that when the light is directly incident on the first transport belt 8. Therefore, the level of output 1 becomes low, and conversely, the level of output 2 becomes high. Each level of output 1 and output 2 changes depending on the type of paper P used (glossiness, whiteness, etc.) and the sensitivity of the light receiving portion.

Therefore, by using the ID sensor that detects the reflected light and the diffuse reflected light as the opening detection sensor 23, the control device 110 (for example, the discharge control unit 110a) is based on the output signal from the opening detection sensor 23. The object that has passed the position facing the opening detection sensor 23 is (i) the first transport belt 8, (ii) the opening 80 of the first transport belt 8, or (iii) the first transport belt. It can be determined whether the paper P is on the 8th sheet. By adjusting the gain of the output signal according to the sensitivities of the first light receiving unit 23b and the second light receiving unit 23 of the opening detection sensor 23, the control device 110 can clearly distinguish the above three states. It may be.

(3-2. How to adjust the flushing timing)
Next, a method of adjusting the flushing timing using the opening detection sensor 23 described above will be described. FIG. 13 is a flowchart showing an operation flow according to the flushing timing adjusting method of the present embodiment. Further, FIG. 14 shows an output signal of the paper detection sensor 22 and an output signal of the opening detection sensor 23 (normally reflected light detection signal, when the paper P is supplied onto the first transport belt 8 having the opening 80. It is a timing chart which shows each of the diffuse reflection light detection signal), the ink ejection timing (at the time of image recording, at the time of flushing), and the timing at which flushing can be executed. Since the paper P is adsorbed on the first transport belt 8 and transported, the transport speed of the first transport belt 8 and the transport speed of the paper P are the same.

First, for example, in a state before factory shipment of the device (printer 100), a worker involved in manufacturing the device operates the operation panel 27 to select a mode for adjusting the flushing timing (S1). By selecting this mode, the opening detection sensor 23 that normally detects the opening 80 that moves due to the traveling of the first transport belt 8 is used as a sensor that detects the paper P, and the paper P in the opening detection sensor 23 is used. It is possible to eject ink from the recording heads 17a to 17c based on the detection of.

Next, the paper detection sensor 22 detects the passage of the tip of the paper P supplied to the first transport belt 8 by the resist roller pair 13 (S2), and then the opening detection sensor detects the passage of the tip of the paper P to the first transport belt 8. When the paper P conveyed by the paper P is detected (S3), the ejection control unit 110a controls the ejection of ink by the recording heads 17a to 17c to apply a check pattern (first chart, second chart) to the paper P. Record (S4).

More specifically, in S4, the ejection control unit 110a has a plurality of ejection timings preset with reference to the detection time point t0 of the paper P by the paper detection sensor 22, and predetermined nozzles (ink ejection ports) of the recording heads 17a to 17c. By ejecting ink from 18), the first chart C1 is recorded on the paper P. Further, the ejection control unit 110a ejects ink from another nozzle of the recording heads 17a to 17c at a plurality of ejection timings preset with reference to the detection time point t2 of the paper P by the opening detection sensor 23. The second chart C2 is recorded on the paper P side by side with the first chart C1 described above.

FIG. 15 schematically shows an example of the first chart C1 and the second chart C2. The first chart C1 includes a first reference line Cr1 and a plurality of first auxiliary lines Cs1. The first reference line Cr1 is based on the detection of the paper P by the paper detection sensor 22 at the reference ejection timing from the predetermined nozzles of the recording heads 17a to 17c (for example, from the time t0 when the paper P is detected by the paper detection sensor 22). A line formed by the ejected ink (after the lapse of T1 hour). The first auxiliary line Cs1 is a line formed by ink ejected from a plurality of timings before and after the reference ejection timing from the predetermined nozzle. The plurality of first auxiliary lines Cs1 are arranged on the paper P in the transport direction of the first reference line Cr1 and the paper P. The first reference line Cr1 and the plurality of first auxiliary lines Cs1 are formed on the paper P in the longitudinal direction of the recording heads 17a to 17c, that is, in parallel with the width direction (belt width direction) of the paper P.

“A to I, 0 to 9” in the figure are reference numerals assigned for convenience corresponding to each position of the first reference line Cr1 and the plurality of first auxiliary lines Cs1. Of these, the reference numeral "0" corresponds to the position of the first reference line Cr1, and the reference numerals "AI, 1 to 9" correspond to the positions of the first auxiliary lines Cs1. In particular, reference numerals “1 to 9” are attached in order from the first reference line Cr1 toward the upstream side for each of the first auxiliary lines Cs1 located on the upstream side with respect to the first reference line Cr1. Further, the symbols "AI" are assigned in order from the first reference line Cr1 toward the downstream side for each of the first auxiliary lines Cs1 located on the downstream side with respect to the first reference line Cr1.

Further, it is assumed that the ejection interval of the ink forming the first reference line Cr1 and the plurality of first auxiliary lines Cs1 is, for example, 50 μsec. Therefore, the ejection timing of the ink forming each line of the first chart C1 is, for example, T1-50 (for example, from the first reference line Cr1 toward the upstream side, based on the ejection timing of the first reference line Cr1. μsec), T1-50 × 2 (μsec), T1-50 × 3 (μsec), ... From the first reference line Cr1 toward the downstream side, for example, T1 + 50 (μsec), T1 + 50 × 2 ( μsec), T1 + 50 × 3 (μsec), ...

On the other hand, the second chart C2 includes a second reference line Cr2 and a plurality of second auxiliary lines Cs2. The second reference line Cr2 is based on the detection of the paper P by the opening detection sensor 23 at the reference ejection timing from another nozzle of the recording heads 17a to 17c (for example, when the paper P is detected by the opening detection sensor 23). A line formed by the ejected ink (after the lapse of t2 to T2 hours). The second auxiliary line Cs2 is a line formed by ink ejected from a plurality of timings before and after the reference ejection timing from the other nozzles. The plurality of second auxiliary lines Cs2 are arranged on the paper P in the transport direction of the second reference line Cr2 and the paper P. The second reference line Cr2 and the plurality of second auxiliary lines Cs2 are formed on the paper P in the longitudinal direction of the recording heads 17a to 17c, that is, in parallel with the width direction (belt width direction) of the paper P.

Further, the ejection interval of the ink forming the second reference line Cr2 and the plurality of second auxiliary lines Cs2 is, for example, 60 μsec. Therefore, the ejection timing of the ink forming each line of the second chart C2 is, for example, T1-60 (for example, T1-60 (), with reference to the ejection timing of the second reference line Cr2, toward the upstream side from the second reference line Cr2. μsec), T1-60 × 2 (μsec), T1-60 × 3 (μsec), ... From the second reference line Cr2 toward the downstream side, for example, T1 + 60 (μsec), T1 + 60 × 2 ( μsec), T1 + 60 × 3 (μsec), ...

As described above, the ink ejection intervals forming each line are different between the first chart C1 and the second chart C2. Therefore, the interval D1 in the transport direction of the paper P of all the lines (first reference line Cr1, first auxiliary line Cs1) included in the first chart C1 and all the lines included in the second chart C2 (first). 2 The distance D2 in the transport direction of the paper P on the reference line Cr2 and the second auxiliary line Cs2) is different from each other. In this embodiment, for example, D1 <D2.

When the check pattern shown in FIG. 15 is recorded on the paper P, the operator looks at the first chart C1 and the second chart C2 on the paper P and is based on the paper detection by the paper detection sensor 22. It is possible to determine the presence or absence and degree of deviation between the ink ejection timing and the ink ejection timing based on the paper detection by the opening detection sensor 23. For example, in the example of FIG. 15, since the first reference line Cr1 of the first chart C1 and the second reference line Cr2 of the second chart C2 are aligned as timings, the operator can eject both of the above inks. It can be determined that the timing is correct (there is no deviation in the discharge timing).

In this way, when the operator looks at the paper P on which the check pattern is recorded in S4 and determines that the ink ejection timings of both of the above are correct (No in S5), it is not necessary to change the flushing timing. , The operator operates the operation panel 27 to input the end of the flushing timing adjustment (S6). In this case, the discharge control unit 110a sets the flushing timing based on the detection time t1 of the opening 80 by the opening detection sensor 23, which is the reference discharge timing immediately before the end of the flushing timing adjustment, that is, the second reference line Cr2. The ejection timing of the ink to be formed (T2 hours after the detection time) is set (maintained) as the flushing timing and stored in the storage unit 28.

When flushing is executed in the installation environment on the user side after the device is shipped, the discharge control unit 110a sets the recording heads 17a to 17c after T2 hours have elapsed from the detection time t1 of the opening 80 by the opening detection sensor 23. Ink is ejected from each nozzle. Since the flushing timing is set as described above, the ink ejected from the recording heads 17a to 17c can pass through the opening 80.

When performing normal printing in the installation environment on the user side, the ejection control unit 110a sets the recording head after the lapse of T1 hours from the time point t0 with reference to the time point t0 when the paper P is detected by the paper detection sensor 22. An image can be recorded on the paper P by ejecting ink from 17a to 17c.

On the other hand, FIG. 16 schematically shows a state in which the first chart C1 and the second chart C2 are displaced. As shown in the figure, when the first reference line Cr1 and the second reference line Cr2 are deviated from each other in the paper transport direction, the operator can perform the ink ejection timing based on the paper detection by the paper detection sensor 22 and the opening. It can be determined that there is a deviation from the ink ejection timing based on the paper detection by the detection sensor 23. Further, in the example of FIG. 16, since the second reference line Cr2 of the second chart C2 is shifted in the earlier direction by the five scales of the first auxiliary line Cs1 of the first chart C1, the ink is ink. As the amount of time lag in the discharge timing of, one scale discharge interval (50 μsec) × number of scales (-5) = -250 μsec can be grasped (minus sign indicates that the discharge timing is earlier than the reference). Indicates that there is).

In this way, the operator looks at the paper P on which the check pattern is recorded in S4, and the ink ejection timing based on the paper detection by the paper detection sensor 22 and the ink ejection based on the paper detection by the opening detection sensor 23. When it is determined that there is a deviation from the timing (Yes in S5), it is necessary to change the flushing timing. Therefore, the operator operates the operation panel 27 to input the adjustment value of the flushing timing (S8). For example, in the example of FIG. 16, the operator inputs a value corresponding to a time shift amount of the ink ejection timing as an adjustment value. As the adjustment value, for example, the number of scales indicating the amount of deviation (for example, "-5") or the value of the amount of deviation itself (for example, "-250") can be used.

As a result, the ejection control unit 110a changes the ejection timing of the ink forming each line of the second chart C2 according to the amount of deviation. For example, the ejection control unit 110a sets the ejection timing of the ink forming the second reference line Cr2 from "T2 hours after the time when the opening 80 is detected by the opening detection sensor 23" to "the opening detection sensor 23. It is changed to "after T2'hours from the time when the opening 80 is detected". In the above example, T2'(sec) = T2 (sec) + 250 (μsec) = T2 + 0.25 (sec). Further, the ejection control unit 110a changes the ejection timing of the ink forming the plurality of second auxiliary lines Cs2 by back calculation based on the ejection timing (after the change) of the ink forming the second reference line Cr2. After that, it returns to S2 and repeats the processing after S2.

After that, the operator looks at the paper P on which the check pattern is recorded in S4, and the ink ejection timing based on the paper detection by the paper detection sensor 22 and the ink ejection timing based on the paper detection by the opening detection sensor 23. If there is a discrepancy in, the operator inputs the adjustment value again in S8 and repeats the above process.

On the other hand, if the operator determines in S4 that there is no such deviation, the process proceeds to S6, and the operator operates the operation panel 27 to input the end of flushing timing adjustment. In this case, the discharge control unit 110a forms a discharge timing, that is, a second reference line Cr2, which is a reference immediately before the end of the flushing timing adjustment as the flushing timing based on the detection time of the opening 80 by the opening detection sensor 23. The flushing timing (after T2'hours from the time when the opening 80 is detected by the opening detection sensor 23) is set as the flushing timing and stored in the storage unit (S7).

When flushing is executed in the installation environment on the user side after the device is shipped, the discharge control unit 110a determines the recording heads 17a to 17c after the time T1 to T2'time when the opening 80 is detected by the opening detection sensor 23 has elapsed. Ink is ejected from each nozzle of. As a result, the ink ejected from the recording heads 17a to 17c at the adjusted flushing timing passes through the opening 80 of the first transport belt 8.

In the above, an example of adjusting the flushing timing for an arbitrary opening 80 of each opening group 82 has been described, but as in the present embodiment, the openings 80 of each opening group 82 are located in a staggered pattern. In the configuration, it is necessary to provide a time difference in flushing timing between the first row (for example, opening row 81a) and the second row (for example, opening row 81b) of each opening group 82. However, the position information of each opening 80 in one opening group 82 (position information between the opening 80 of the opening row 81a and the opening 80 of the opening row 81b) is stored in the storage unit 28 in advance. Since the traveling speed of the first transport belt 8 is constant, the above time difference can be obtained by calculation.

Therefore, for example, when the flushing timing for the opening 80 of the opening row 81a is set (maintained or changed) by the above method, the flushing timing for the opening 80 of the next opening row 81b is set to the opening of the opening row 81a. It can be set (maintained or changed) by adding the above time difference to the flushing timing with respect to 80. Therefore, by ejecting ink from the corresponding nozzles of the recording heads 17a to 17c at the flushing timing set above, flushing that allows the ink to pass through the opening 80 of the opening row 81b can be executed. ..

(4. Effect)
As described above, in the present embodiment, the opening detection sensor 23 that originally detects the opening 80 is also used as a sensor that detects the paper P, and the ejection timing based on the detection of the paper P by the paper detection sensor 22. Ink is ejected and the first chart C1 is recorded on the paper P, and the ink is ejected at the ejection timing based on the detection of the paper P by the opening detection sensor 23, and the second chart C2 is ejected on the paper P. Is recorded (S2 to S4). Then, based on the instruction input by the operation panel 27 after recording the first chart C1 and the second chart C2 on the paper P, the setting time is set with reference to the detection time point of the opening 80 by the opening detection sensor 23. The flushing timing is adjusted (S6 to S8). To adjust the flushing timing, not only the flushing timing is changed based on the input of the adjustment value in S8, but also the default flushing timing is maintained as it is based on the input of the adjustment end in S6. That is also included.

By recording the first chart C1 and the second chart C2 on the paper P as described above, the operator involved in the manufacture of the apparatus sees the first chart C1 and the second chart C2 and sees the opening. It is possible to easily determine whether or not the ink ejection timing based on the detection by the detection sensor 23 matches the regular timing. That is, the operator determines whether or not the ink ejection timing at the time of flushing based on the detection of the opening 80 by the opening detection sensor 23 is correct (whether or not the ejected ink can pass through the opening 80). An image (second chart C2) obtained by actually ejecting ink onto the paper P at a timing based on the detection of the paper P by the opening detection sensor 23, and a paper by another sensor (paper detection sensor 22). It can be easily determined by comparing it with another image (first chart C1) obtained by ejecting ink at a timing based on the detection. Then, the worker can input an instruction to adjust (change or maintain) the flushing timing based on the above determination result.

Further, a user using the manufactured printer 100 can grasp the state of the printer 100 by having the printer 100 record a check pattern (first chart C1 and second chart C2).

A user who feels that the printer 100 may be malfunctioning can operate the operation panel 27 to record a check pattern. The user can know about recording such a check pattern from a help screen stored in the storage unit 28 and displayed on the operation panel 27, a manual attached to the printer 100, or the like. The user can determine the state of the printer 100 with respect to the ink ejection timing at the time of flushing by looking at the check pattern according to the help screen or the manual. Alternatively, the user may send a check pattern to a person who manufactured the printer 100, a person who sold the printer 100, or the like to determine the state of the printer 100.

When it is found from the check pattern that it is better to adjust the printer 100, the user may adjust the flushing timing in the same manner as the above-mentioned worker, or the person who manufactured or sold the printer 100, etc. You may ask for adjustment.

Further, the main control unit 110c may record a check pattern at predetermined intervals so that the user can confirm the state of the printer 100. The recording interval may be for each number of prints, or for each time such as the elapsed time or the operating time of the printer 100. Further, instead of recording the check pattern, the main control unit 110c may display a display prompting the operation panel 27 to record the check pattern at predetermined intervals.

On the device side, the flushing timing is adjusted for each device based on the above instruction input, so even if there are tolerances (detection tolerance, installation position tolerance) in the opening detection sensor 23, the installation on the user side after the device is shipped. When flushing is performed in an environment, ink can be ejected from the recording heads 17a to 17c at an appropriate flushing timing for each device so that the ink can pass through the opening 80 with high accuracy. Therefore, in order to reduce the influence of the tolerance of the opening detection sensor 23, it is not necessary to form the opening 80 of the first transport belt 8 to be large. As a result, the following effects can be further obtained.

That is, since the size of the opening 80 can be suppressed to the minimum necessary, it is possible to suppress a decrease in the strength of the first transport belt 8. Further, even when the paper P is placed on the first transport belt 8 so as to overlap the opening 80 not used for flushing during normal image formation, the paper P is inside the opening 80 because the opening 80 is small. It is possible to suppress bending. Therefore, deterioration of the image quality of the recorded image due to the bending of the paper P can be suppressed.

Further, since the influence of the tolerance of the opening detection sensor 23 is reduced, it is possible to expand the design margin of the device related to the installation and assembly of the component including the opening detection sensor 23.

Further, according to the method of adjusting the flushing timing of the present embodiment, the flushing timing can be easily adjusted based on the instruction input of the operator, and the work required for the adjustment can be easily completed.

In particular, in S6, the flushing timing is adjusted based on the adjustment value input after recording the first chart C1 and the second chart C2 on the paper P. This makes it possible to appropriately change the flushing timing based on the above adjustment value.

Further, the first chart S1 includes the first reference line Cr1, and the second chart S2 includes the second reference line Cr2. By recording such a first chart C1 and a second chart C2 on the paper P, the first reference line Cr1 of the first chart C1 and the second chart C2 in the transport direction of the paper P are recorded. 2 Presence or absence of deviation between the ink ejection timing based on the detection of the paper P by the paper detection sensor 22 and the ink ejection timing based on the detection of the paper P by the opening detection sensor 23 based on the positional deviation from the reference line Cr2. Can be easily recognized by the operator. Therefore, the operator can easily determine whether or not it is necessary to adjust the flushing timing (ink ejection timing based on the detection of the opening 80 by the opening detection sensor 23).

Further, the first chart C1 further includes a plurality of first auxiliary lines Cs1, and the second chart C2 further includes a plurality of second auxiliary lines Cs2. In this case, the amount of deviation between the first reference line Cr1 of the first chart C1 and the second reference line Cr2 of the second chart C2 in the transport direction of the paper P is set between the first reference line Cr1 and the second reference. The operator can recognize the line Cr2 in association with the time interval between the line Cr2 and the first auxiliary line Cs1 formed at the same discharge timing, and the recognition becomes easy. That is, in the example of FIG. 15, the discharge timing deviation between the first reference line Cr1 and the second reference line Cr2 is formed so that the discharge timings of the first reference line Cr1 and the second reference line Cr2 coincide with each other. It becomes easy for the operator to recognize it in association with the time interval (for example, 50 μsec × 5 (absolute value)) between the first auxiliary line Cs1 of the symbol “5”.

Further, the distance D1 in the transport direction of the paper P of all the lines included in the first chart C1 and the distance D2 in the transport direction of the paper P of all the lines included in the second chart C2 are different from each other ( See FIG. 14). In this case, the operator can easily find the lines formed by matching the discharge timings on the first chart C1 and the second chart C2. This makes it easier for the operator to recognize the amount of deviation between the first reference line Cr1 and the second reference line Cr2.

The opening detection sensor 23 is an optical sensor that detects specularly reflected light and diffusely reflected light. By using such an opening detection sensor 23, the discharge control unit 110a is detected based on the output signal from the opening detection sensor 23, that is, the detection signal of the positively reflected light and the detection signal of the diffusely reflected light. Is the first transport belt 8 (the area where the paper P is not placed), the opening 80 of the first transport belt 8, or the paper P on the first transport belt 8 to be reliably distinguished and recognized. be able to. This makes it possible to reliably realize the above-mentioned flushing timing adjusting method using the opening detection sensor 23. Further, an ID sensor that detects specular reflected light and diffuse reflected light can be used as the opening detection sensor 23, and the ID sensor can be effectively used.

The opening detection sensor 23 may be a reflection type optical sensor that detects specularly reflected light. Since the reflection type optical sensor outputs a detection signal such as the output 1 shown in FIG. 12, the discharge control unit 110a detects the first transport belt 8 based on the detection signal of the specularly reflected light. It is possible to realize the flushing timing adjusting method of the present embodiment by distinguishing and recognizing which of the opening 80 of the first transport belt 8 and the paper P on the first transport belt 8 is. Further, the method of adjusting the flushing timing of the present embodiment can also be applied to a case where the paper transfer control is performed so as to be completely separated from the opening of the transfer belt, as in Patent Document 3, for example. In some cases, it is also possible to use a reflective optical sensor as the opening detection sensor 23.

In the above, the example in which the operator directly operates the operation panel 27 to input the flushing timing instruction (instruction of the end of adjustment or input of the adjustment value) has been described, but the operator inputs the instruction on the PC. You may do it. In this case, when the device (printer 100) receives the above-mentioned instruction input via the communication unit 29, the device side can adjust the flushing timing based on the above-mentioned instruction input.

From the above, the inkjet recording apparatus (printer 100) directly used to carry out the above-mentioned flushing timing adjustment method can be expressed as follows. That is, the inkjet recording device conveys the recording heads 17a to 17c having a plurality of nozzles and the paper P, and executes flushing to eject ink at a timing different from the timing at which the recording heads 17a to 17c contribute to image formation. When the ink is passed, the endless first transport belt 8 having openings 80 for passing the ink at a plurality of locations in the transport direction of the paper P, and the resist roller pair 13 for supplying the paper P to the first transport belt 8 , The paper detection sensor 22 that detects the paper P supplied from the resist roller pair 13 to the first transport belt 8, and the opening 80 that moves as the first transport belt 8 travels, and the first transport belt It includes an opening detection sensor 23 that detects the upper paper P, and an ejection control unit 110a that controls the ejection of ink in the recording heads 17a to 17c. Then, the ejection control unit 110a ejects ink from predetermined nozzles of the recording heads 17a to 17c at a plurality of ejection timings preset with reference to the time when the paper P is detected by the paper detection sensor 22, thereby ejecting the paper P. To record the first chart C1 and eject ink from different nozzles of the recording heads 17a to 17c at a plurality of ejection timings preset with reference to the time when the paper P is detected by the opening detection sensor 23. The second chart C2 is recorded side by side with the first chart C1 on the paper P. Further, the printer 100 has an input receiving unit 30 (operation panel 27, communication unit 29) that receives an instruction input for adjusting the flushing timing indicating the timing of ejecting ink when the recording heads 17a to 17c execute flushing. Further prepare. The discharge control unit 110a adjusts the flushing timing set based on the detection time of the opening 80 by the opening detection sensor 23 based on the instruction input received by the input reception unit 30.

(5. Other examples of check patterns)
FIG. 17 schematically shows another example of the first chart C1 and the second chart C2 recorded on the paper P when the flushing timing is adjusted. As shown in the figure, the intervals in the paper transport direction of all the lines (first reference line Cr1 and first auxiliary line Cs1) included in the first chart C1 and all the lines included in the second chart C2. The intervals of the lines (second reference line Cr2, second auxiliary line Cs2) in the paper transport direction may be the same as each other. Further, the line widths of all the lines included in the first chart C1 may be different from each other, and the line widths of all the lines included in the second chart C2 may be different from each other. Then, the first chart C1 may include lines having the same line width as the individual lines included in the second chart C2.

FIG. 18 schematically shows a state in which the first chart C1 and the second chart C2 having the configuration shown in FIG. 17 are displaced from each other. Even when the first chart C1 and the second chart C2 are recorded on the paper P in the flushing timing adjustment mode, the operator recognizes the positional deviation between the first chart C1 and the second chart C2. be able to. That is, based on the first chart C1 and the second chart C2, the ink ejection timing based on the detection of the paper P by the paper detection sensor 22 and the ink ejection based on the detection of the paper P by the opening detection sensor 23. The operator can recognize the deviation from the timing. Therefore, even when the first chart C1 and the second chart C2 are recorded on the paper P, the operator needs to adjust the flushing timing based on the first chart C1 and the second chart C2. It is possible to easily determine the presence or absence of.

(6. Identification of flushing execution timing (1))
In the printer 100 of the present embodiment, as shown in FIGS. 6 to 9, the ink passes through the opening 80 (the portion shown in black) of the opening group 82 located in a pattern corresponding to the size of the paper P. In the configuration in which the flushing is performed so as to be performed, each paper P is supplied to the first transport belt 8 so that the paper P is positioned so as to be displaced from the opening 80 in the paper transport direction. When performing such paper transport control, the ejection control unit 110a flushes based on the detection result of the opening 80 by the opening detection sensor 23 and the detection result of the paper P by the opening detection sensor 23. The executable timing may be specified. Here, the flushing execution enable timing is any one of the inks ejected from the recording heads 17a to 17c among the openings 80 of the openings group 82 located at a plurality of locations in the paper transport direction. It is an ink ejection timing that can pass through at least a part of the opening 80 of the ink.

For example, as shown in FIG. 6, when a plurality of sheets P of A4 size (horizontal placement) are supplied to the first transport belt 8 at equal intervals, the opening detection sensor 23 uses the opening groups 82A, 82C, 82F. Each of the openings 80 is detected. Further, since the paper P is placed on the openings 80 of the openings groups 82B, 82D, and 82E so as to overlap each other, these openings 80 are not detected by the opening detection sensor 23 (the paper P described above is the opening detection). Detected by sensor 23). Therefore, the discharge control unit 110a determines the timing at which the openings 80 of the openings groups 82A, 82C, and 82F detected by the opening detection sensor 23 face the recording heads 17a to 17c due to the traveling of the first transport belt 8. It can be specified as the above flushing enablement timing.

By specifying the flushing executable timing by the ejection control unit 110a, when the flushing is actually executed, ink is ejected from the recording heads 17a to 17c at at least one of the specified flushing executable timings, and the paper P It can pass through an opening 80 that does not overlap with. As a result, flushing can be performed with high accuracy.

Further, the paper P is controlled to be supplied to the first transport belt 8 so that the paper P is placed on the first transport belt 8 so as to be displaced from the opening groups 82A, 82C, and 82F in the paper transport direction. However, the transport of the paper P is delayed for some reason (for example, slip on the roller surface during the transport to the first transport belt 8), and the paper P becomes the openings 80 of the openings groups 82A, 82C, and 82F. It is also possible that they are placed on top of each other. Even in this case, since the flushing execution timing is specified based on the actual detection of the opening 80 and the paper P by the opening detection sensor 23 in the vicinity of the upstream side of the recording heads 17a to 17c, the paper P overlaps. The closed opening 80 is not detected by the opening detection sensor 23, and the timing at which the opening 80 and the recording heads 17a to 17c face each other is not specified as the flushing executable timing. As a result, it is possible to avoid executing flushing at the timing when the opening 80 and the recording heads 17a to 17c face each other, and to avoid a situation in which the paper P overlapping the opening 80 is contaminated with ink during flushing.

When the paper P is placed so as to overlap the opening 80 to be flushed for some reason as described above, the ejection control unit 110a avoids the execution of flushing to the opening 80 and takes the following alternative measures. Control to execute (1) to (3) may be performed.

(1) The ejection control unit 110a is an opening 80 (an opening located in a pattern according to the size of the paper P), which was not planned to be flushed next to the paper P placed so as to overlap the opening 80. When an opening 80) other than the 80) is detected by the opening detection sensor 23, the recording heads 17a to 17c are relative to the opening 80 (at the timing when the opening 80 faces the recording heads 17a to 17c). May perform flushing.

(2) The discharge control unit 110a executes flushing (star flushing) on the recording heads 17a to 17c with respect to the paper P overlapping the opening 80 (at the timing when the paper P faces the recording heads 17a to 17c). You may let me. In this case, it is desirable to disperse and eject the ink on the paper P so as not to affect the image quality of the recorded image on the paper P.

(3) The paper supply control unit 110b controls the resist roller pair 13 so that the opening 80 appears between the paper P placed so as to overlap the opening 80 and the paper P to be supplied next. , The delivery of the next-supplied paper P is delayed. Then, the discharge control unit 110a flushes the recording heads 17a to 17c with respect to the opening 80 located between the two sheets P (at the timing when the opening 80 faces the recording heads 17a to 17c). You may let it run.

When flushing is performed on the paper P, for example, the main control unit 110c may display an error on the display unit of the operation panel 27 to notify the outside that such flushing has been performed. good. Further, the supply timing of the paper P is controlled by the control of the resist roller pair 13 by the paper supply control unit 110b according to the frequency with which the paper P is placed so as to overlap the opening 80 to be flushed, and the first transport belt 8 The position of the paper P placed on the paper P may be corrected. Further, in the main control unit 110c, in order to reduce the situation where the back surface of the paper P (the surface in contact with the first transport belt 8) placed so as to overlap the opening 80 is contaminated with the ink adhering to the periphery of the opening 80. Depending on the frequency, a display prompting the cleaning of the first transport belt 8 may be displayed on the display unit of the operation panel 27.

In the above, the first transport belt 8 is configured by using a belt in which a plurality of opening groups 82 are irregularly located in the paper transport direction (the intervals in the paper transport direction of each opening group 82 change). However, even if each opening group 82 or each opening 80 is configured by using a belt located at equal intervals in the paper transport direction and at intervals equal to or less than the length of the minimum size paper P in the paper transport direction. good. When such a first transport belt 8 is used, for example, the paper supply control unit 110b first transports a plurality of sheets of paper P at regular intervals regardless of the position of the opening 80 of the first transport belt 8. Each paper P can be sequentially supplied to the first transport belt 8 by controlling the resist roller pair 13 so that the paper P is placed on the belt 8. Even in this case, the discharge control unit 110a identifies the flushing execution timing by the same method as described above, that is, based on the detection results of the opening 80 and the paper P by the opening detection sensor 23, and the recording heads 17a to 17a. It is possible to have 17c perform flushing, which can provide the same effect as described above.

By the way, when the discharge control unit 110a specifies a plurality of flushing executable timings, the recording heads 17a to 17c may execute flushing at all of the specified flushing executable timings, and some of them may be flushed. The recording heads 17a to 17c may be made to execute flushing at the timing when flushing can be executed. For example, the ejection control unit 110a selects and selects the timing at which ink is actually ejected from the recording heads 17a to 17c according to the usage state of each nozzle of the recording heads 17a to 17c from a plurality of flushing executable timings. The recording heads 17a to 17c may be flushed at the timing. In this case, the recording heads 17a to 17c are flushed at the minimum necessary timing, and the nozzle clogging prevention effect due to the flushing can be obtained. Further, the usage state of each nozzle can be determined by the ejection control unit 110a based on, for example, the image data used for printing (image data of the image recorded on the paper P). Therefore, by executing flushing according to the usage state of each nozzle, unnecessary flushing can be avoided and an increase in ink consumption due to unnecessary flushing can be avoided.

(7. Identification of flushing execution timing (2))
As shown in FIG. 5, the first transport belt 8 of the present embodiment has a configuration in which one opening group 82 has a plurality of staggered openings 80. More specifically, the first transport belt 8 has openings 82 at a plurality of positions in the paper transport direction. The opening group 82 has a plurality of rows of openings 81 in which the openings 80 are arranged in the belt width direction perpendicular to the paper transport direction. In each opening group 82, the opening 80 of each opening row 81 is positioned so as to partially overlap the opening 80 of the adjacent opening row 81 in the belt width direction when viewed from the paper transport direction. do.

The opening detection sensor 23 used in the present embodiment is provided with a size for detecting one opening 80 (see FIG. 5). In this case, it can be said that the opening detection sensor 23 detects a specific opening 80 of a specific opening row 81 (for example, the opening row 81a) in each opening group 82. Further, as described above, the storage unit 28 stores in advance the position information of all the openings 80 of the first transport belt 8.

In such a configuration that the printer 100 has the first transport belt 8 and the opening detection sensor 23, the discharge control unit 110a may perform the following control. That is, the discharge control unit 110a includes preset position information of each opening 80, a detection result of the opening 80 of the specific opening row 81a detected by the opening detection sensor 23, and an opening detection sensor. Based on the detection result of the paper P detected in 23, whether or not there is an opening 80 overlapping the paper P in the other opening row 81b of the opening group 82 to which the specific opening row 81a belongs. The determination may be made, and based on the determination result, the flushing execution enable timing for the opening 80 of the other opening row 81b may be specified.

For example, when the ejection control unit 110a determines that the paper P does not overlap the other opening row 81b, the ejection control unit 110a specifies the ink ejection timing for the opening 80 of the other opening row 81b as the flushing executable timing. May be good. Further, when the ejection control unit 110a determines that the paper P completely overlaps the opening 80 of the other opening row 81b, the ejection control unit 110a flushes the ink ejection timing with respect to the opening 80 of the other opening row 81b. It may be excluded from the possible timing. Further, when the ejection control unit 110a determines that the paper P overlaps a part of the opening row 81b, the ejection control unit 110a determines the ink ejection timing for the remaining region of the opening row 81b (the region that does not overlap with the paper P). It may be specified as the flushing enablement timing.

FIG. 19 shows the output signals of various sensors, and shows the output signals of the two openings 80 of the two opening rows 81a (first opening row) and 81b (second opening row) belonging to each opening group 82. It is a timing chart which shows the relationship between the position and the flushing execution possible timing. In the example of the figure, the ejection control unit 110a is the ink for the opening 80 of the opening row 81b of the opening row 81b of each opening group 82 where the papers P do not overlap (positions shifted in the transport direction). Is specified as the flushing executable timing (see tm3 and tm4). Further, when a part of the opening 80 of the opening row 81b overlaps with the paper P, the ejection control unit 110a determines the timing of ejecting ink to the remaining region of the opening 80 excluding the part. , It is specified as the flushing executable timing (see tm1 and tm2).

In the first transport belt 8, each opening 80 is staggered, and in a configuration in which the opening detection sensor 23 detects the opening 80 of the specific opening row 81a, the opening detection sensor 23 is the other opening. Even if the opening 80 of the row 81b cannot be detected, the discharge control unit 110a can obtain the position information of each opening 80, the detection result of the opening 80 of the specific opening row 81a, and the detection result of the paper P. It can be determined whether or not the paper P is placed on the opening 80 of the other opening row 81b so as to overlap with the opening 80. Therefore, the discharge control unit 110a sets the flushing execution enable timing based on the above determination result, so that even if the opening detection sensor 23 cannot detect the opening 80 of the other opening row 81b, the opening Flushing can be appropriately performed on the unit 80.

Further, as described above, when the ejection control unit 110a determines that the paper P is positioned at a position deviated from the opening 80 of the other opening row 81b, the ejection control unit 110a can flush the ink ejection timing with respect to the opening 80. It is specified as the timing. In this case, the ejection control unit 110a can eject ink to the recording heads 17a to 17c at the specified flushing executable timing to flush the opening 80 of the opening row 81b.

Further, when the ejection control unit 110a determines that the paper P overlaps a part of the opening 80 of the other opening row 81b, the ejection control unit 110a can flush the ink ejection timing with respect to the remaining region of the opening 80. It is specified as the timing. In this case, the ejection control unit 110a ejects ink to the recording heads 17a to 17c at the specified flushing executable timing, and flushes the region of the opening 80 of the opening row 81b that does not overlap with the paper P. be able to. It should be noted that the discharge control unit 110a can determine and determine whether or not flushing is actually performed at the specified flushing execution timing.

Further, when the ejection control unit 110a determines that the opening 80 of the opening row 81b overlapping the paper P exists, it is desirable that the ejection of ink to the opening 80 by the recording heads 17a to 17c is stopped. That is, it is desirable that the ejection control unit 110a excludes the ink ejection timing for the opening 80 from the flushing executable timing. In this case, during flushing based on the flushing enablement timing, ink is not ejected to the paper P placed so as to overlap the opening 80, and it is possible to avoid a situation in which the paper P is contaminated with the ink. ..

Further, when the paper P overlaps a part of the opening 80, the length of the remaining area of the opening 80 (the area that does not overlap with the paper P) in the paper transport direction becomes a predetermined value (for example, several mm) or less. In this case, when flushing is performed on the remaining area of the opening 80, ink directed to other than the remaining area of the opening 80 lands on the paper P due to the variation in the ejection angle of the ink ejected during flushing. Paper P may become dirty.

Therefore, it is desirable that the ejection control unit 110a stops the ejection of ink to the opening 80. That is, the ejection control unit 110a determines that the paper P overlaps a part of the opening 80 of the opening row 81b, and the length of the remaining region of the opening 80 in the paper transport direction is equal to or less than a predetermined value. If this is the case, it is desirable to stop the ink ejection from the recording heads 17a to 17c to the opening 80. In this case, it is possible to avoid the above-mentioned situation in which the paper P is soiled due to the variation in the ink ejection angle at the time of executing flushing with respect to the opening 80 (particularly the remaining area that does not overlap with the paper P).

Further, even when the opening 80 of each opening group 82 (opening row 81a, opening row 81b) and the paper P are separated on the first transport belt 8, for example, the paper P is separated for some reason. When the transfer of the ink is delayed and the separation distance becomes a predetermined distance (for example, several mm) or less, when flushing is performed on the opening 80, the ejection angle of the ink ejected at the time of flushing is determined in the same manner as described above. Due to the variation, ink directed to other than the opening 80 may land on the nearby paper P and stain the paper P.

Therefore, the ejection control unit 110a obtains the separation distance between the opening 80 and the paper P in the paper transport direction based on the detection result of the opening 80 and the paper P by the opening detection sensor 23, and the separation distance is predetermined. When the distance is less than or equal to the distance, it is desirable to stop the ink ejection from the recording heads 17a to 17c to the opening 80. In this case, it is possible to avoid the above-mentioned situation in which the paper P placed in the vicinity of the opening 80 becomes dirty due to the variation in the ejection angle of the ink when flushing the opening 80.

In the above, the example in which one opening detection sensor 23 is used corresponding to one opening 80 of the specific opening row 81a has been described, but further, the opening 80 of the other opening row 81b has been described. Another opening detection sensor for detection may be provided. Then, the paper P is detected by the opening detection sensor, and the ejection control unit 110a detects the other openings 80 and the paper P of the other opening row 81b by the opening detection sensor. The flushing enablement timing for the opening 80 in row 81b may be specified.

As described above, the printer 100 as the inkjet recording device of the present embodiment includes the opening detection sensor 23 that detects the specular reflected light and the diffuse reflected light. In this case, as described above, the discharge control unit 110a can distinguish and recognize the first transport belt 8, the opening 80, and the paper P based on the output signal from the opening detection sensor 23. Therefore, before the printer 100 is shipped from the factory, the above-described flushing timing adjustment method can be implemented based on the output result of the opening detection sensor 23. On the other hand, after shipment from the factory, the above-mentioned flushing control can be performed by the discharge control unit 110a based on the output result of the opening detection sensor 23. That is, the opening detection sensor 23 used for adjusting the flushing timing before shipment from the factory can be effectively used for flushing control after shipment from the factory.

(8. Others)
In the above, the case where the paper P is attracted to the first transport belt 8 by negative pressure suction and transported has been described. However, the first transport belt 8 is charged and the paper P is electrostatically attracted to the first transport belt 8. It may be transported (electrostatic adsorption method).

In the above, an example of using a color printer that records a color image using four colors of ink has been described as an inkjet recording device, but when a monochrome printer that records a monochrome image using black ink is used. However, it is possible to apply the flushing timing adjustment method and flushing control of the present embodiment.

The present invention can be used in an inkjet recording device such as an inkjet printer.

8 1st transport belt 13 Resist roller pair (recording medium supply unit)
17a to 17c Recording head 18 Ink ejection port (nozzle)
22 Paper detection sensor (recording medium detection sensor)
23 Opening detection sensor 27 Operation panel (input reception)
29 Communication Department (Input Reception Department)
30 Input reception unit 80 Openings 81, 81a, 81b Opening rows 82, 82A to 82F Openings 100 Printer (inkjet recording device)
110a Discharge control unit C1 1st chart C2 2nd chart Cr1 1st reference line Cr2 2nd reference line Cs1 1st auxiliary line Cs2 2nd auxiliary line P paper (recording medium)

Claims (18)

A flushing timing adjusting method in an inkjet recording apparatus that adjusts the flushing timing, which is the ink ejection timing when flushing ink is ejected from a recording head toward an opening of an endless conveyor belt.
The recording medium supplied from the recording medium supply unit to the transport belt is detected by the recording medium detection sensor, and the recording medium is detected by the recording medium detection sensor.
The recording medium transported by the transport belt is detected by the opening detection sensor that detects the opening that moves as the transport belt travels.
The first chart is recorded on the recording medium by ejecting ink from a predetermined nozzle of the recording head at a plurality of ejection timings preset with reference to the detection time of the recording medium by the recording medium detection sensor. In addition, ink is ejected from another nozzle of the recording head at a plurality of ejection timings preset with reference to the detection time of the recording medium by the opening detection sensor, whereby the recording medium is subjected to a second ejection. The chart is recorded side by side with the first chart.
Based on the instruction input after recording the first chart and the second chart on the recording medium, the flushing timing set based on the detection time of the opening by the opening detection sensor is adjusted. Flushing timing adjustment method characterized by doing. Adjusting the flushing timing is characterized by including adjusting the flushing timing based on the adjustment values input after recording the first chart and the second chart on the recording medium. The flushing timing adjusting method according to claim 1. The first chart shows a first reference line formed by ink ejected from the predetermined nozzle of the recording head at a reference ejection timing based on the detection of the recording medium by the recording medium detection sensor. Including,
The second chart shows a second reference line formed by ink ejected from the other nozzle of the recording head at a reference ejection timing based on the detection of the recording medium by the opening detection sensor. The flushing timing adjusting method according to claim 1 or 2, wherein the flushing timing adjustment method is included. The first chart is formed by ink ejected from a plurality of timings before and after a reference ejection timing from the predetermined nozzle, and a plurality of first charts arranged in the transport direction of the first reference line and the recording medium. Including auxiliary lines
The second chart is formed by ink ejected from a plurality of timings before and after a reference ejection timing from the other nozzles, and a plurality of second charts arranged in the transport direction of the second reference line and the recording medium. The flushing timing adjusting method according to claim 3, further comprising an auxiliary line. The spacing of all the lines included in the first chart in the transport direction of the recording medium and the spacing of all the lines included in the second chart in the transport direction of the recording medium are different from each other. The flushing timing adjusting method according to claim 4, wherein the flushing timing is adjusted. The spacing in the transport direction of the recording medium for all the lines included in the first chart and the spacing in the transport direction of the recording medium for all the lines included in the second chart are the same as each other. can be,
The line widths of all the lines included in the first chart are different from each other.
The line widths of all the lines included in the second chart are different from each other.
The flushing timing adjusting method according to claim 4, wherein the first chart includes lines having the same line width as the individual lines included in the second chart. The flushing timing adjusting method according to any one of claims 1 to 6, wherein the opening detection sensor is an optical sensor that detects specular reflected light and diffuse reflected light. A recording head with multiple nozzles that eject ink,
When flushing is performed to eject the ink at a timing different from the timing at which the recording head contributes to image formation while conveying the recording medium, an opening through which the ink is passed is formed in the conveying direction of the recording medium. Endless transport belts in multiple locations and
A recording medium supply unit that supplies the recording medium to the conveyor belt, and a recording medium supply unit.
A recording medium detection sensor that detects a recording medium supplied from the recording medium supply unit to the conveyor belt, and a recording medium detection sensor.
An opening detection sensor that detects the opening that moves as the transport belt travels and also detects the recording medium on the transport belt.
A discharge control unit for controlling the discharge of the ink in the recording head is provided.
The ejection control unit ejects ink from a predetermined nozzle of the recording head to the recording medium at a plurality of ejection timings set in advance with reference to the detection time of the recording medium by the recording medium detection sensor. The first chart is recorded, and ink is ejected from another nozzle of the recording head at a plurality of ejection timings preset with reference to the detection time of the recording medium by the opening detection sensor. An inkjet recording apparatus characterized in that a second chart is recorded on a recording medium side by side with the first chart. Further, an input receiving unit for receiving an instruction input for adjusting the flushing timing indicating the timing of ejecting the ink when the recording head executes the flushing is provided.
The claim is characterized in that the discharge control unit adjusts the flushing timing set with reference to the detection time of the opening by the opening detection sensor based on the instruction input received by the input reception unit. Item 8. The inkjet recording apparatus according to item 8. The discharge control unit identifies the flushing execution possible timing based on the detection result of the opening by the opening detection sensor and the detection result of the recording medium.
The flushing execution timing is such that the ink ejected from the recording head at the time of executing the flushing can pass through at least a part of any of the openings among the plurality of openings. The inkjet recording apparatus according to claim 8 or 9, wherein the ejection timing is the same as that of the ink jet recording apparatus. 10. The discharge control unit is characterized in that when a plurality of the flushing executable timings are specified, the recording head executes the flushing at at least one of the specified flushing executable timings. The inkjet recording apparatus according to the above. The discharge control unit determines the usage state of each nozzle of the recording head based on the image data of the image recorded on the recording medium, and based on the determination result, actually from the plurality of flushing executable timings. The inkjet recording apparatus according to claim 11, wherein a timing for ejecting the ink from the recording head is selected, and the recording head is made to execute the flushing at the selected timing. The transport belt has openings at the plurality of locations.
The opening group is configured to have a plurality of rows of openings in which the openings are arranged in a belt width direction perpendicular to the transport direction of the recording medium.
In each opening group, the openings of each opening row are positioned so as to partially overlap the openings of the adjacent opening rows in the belt width direction when viewed from the transport direction.
The opening detection sensor detects a specific opening in a specific row of openings in each opening group.
The discharge control unit detects the preset position information of each opening, the detection result of the opening of the specific opening row detected by the opening detection sensor, and the opening detection sensor. Based on the detection result of the recording medium, it is determined whether or not there is an opening overlapping the recording medium in another opening row of the opening group to which the specific opening row belongs, and the determination is made. The inkjet recording apparatus according to any one of claims 10 to 12, wherein the flushing enable timing with respect to the opening of the other opening row is specified based on the result. When the ejection control unit determines that the recording medium is located at a position deviated from the opening of the other opening row in the transport direction, the ejection timing of the ink with respect to the opening is set as the flushing executable timing. The inkjet recording apparatus according to claim 13, wherein the inkjet recording apparatus is specified. When the ejection control unit determines that the recording medium overlaps a part of the openings in the other opening row, the ejection control unit can execute the flushing of the ink ejection timing with respect to the remaining region of the openings. The inkjet recording apparatus according to claim 13 or 14, characterized in that it is specified as a timing. The discharge control unit determines that the recording medium overlaps a part of the openings in the other opening row, and the length of the remaining region of the openings in the transport direction is equal to or less than a predetermined value. The inkjet recording apparatus according to claim 15, further comprising stopping the ejection of the ink to the opening by the recording head. The discharge control unit obtains a separation distance between the opening and the recording medium in the transport direction based on the detection result of the opening and the recording medium by the opening detection sensor, and the separation distance is predetermined. The inkjet recording apparatus according to any one of claims 10 to 16, wherein when it is determined that the distance is equal to or less than the distance, the ejection of the ink to the opening by the recording head is stopped. The inkjet recording device according to any one of claims 8 to 17, wherein the opening detection sensor is an optical sensor that detects specular reflected light and diffuse reflected light.

Images