Patent Application
20230146482
The present invention relates to a flushing timing adjustment method of an inkjet recording device and an inkjet recording device therefor.
Use of quick-drying ink in inkjet printers and other inkjet recording devices tends to clog nozzles of recording heads easily due to thickening of ink by drying. Thickened ink needs to be discharged before printing on the paper. An ink discharging operation that does not contribute to image formation on the paper is also referred to herein as flushing (idle discharge).
Conventional flushing techniques are disclosed in, for example, Patent Literature 1 to 3. In Patent Literature 1, the flushing is performed by discharging ink from the recording heads between sheets of paper (so-called “between the papers”) supplied to a conveyance belt and causing the ink to pass through openings of the conveyance belt. An opening detection sensor detects the positions of the openings in the conveyance belt, and the discharge of ink during flushing is controlled in accordance with the detection result.
Patent Literature 2 discloses a technique to correct the ink discharge timing relative to the openings by taking into account the effect of variations in the pitch of the openings in the paper conveyance direction due to, for example, a perimeter tolerance of the conveyance belt.
For example, when the paper is placed on the conveyance belt overlapping the openings, paper deflection occurs and a distance (gap) between the recording head and the paper becomes uneven. This may degrade the quality of the image to be recorded on the paper. In Patent Literature 3, the paper is supplied to the conveyance belt so as not to overlap the openings, thus suppressing the deterioration in quality of the recorded image due to the paper deflection.
An opening detection sensor has a detection tolerance (variations in detection accuracy) and an installation position tolerance (variations in installation position). Even when a device is designed using a center value of each tolerance, accumulating the tolerances should increase the variations in ink discharge timing during flushing (flushing timing) between devices. To facilitate handling of such variations in the flushing timing, it may be possible, for example, to enlarge the openings of the conveyance belt. However, the enlarged openings may lead to a decrease of the strength of the conveyance belt and eventually break the conveyance belt. In addition, the enlarged openings may also lead to a decrease in print quality due to the change of the gap caused by the deflection of the paper that overlaps the openings, as described in Patent Literature 3. For this reason, it is preferable to form the openings as small as possible.
Therefore, without forming the opening larger than necessary to reduce the effect of the tolerance of the opening detection sensor, it is necessary to properly adjust the flushing timing for each device such that the ink discharged from the recording heads during flushing can accurately pass through the openings. Such flushing timing adjustment, however, has not been proposed in the past.
In view of the above problems, it is an object of the present invention to provide a flushing timing adjustment method capable of properly adjusting the flushing timing and executing the flushing accurately, without unnecessarily enlarging the openings to decrease the effect of the tolerance of the opening detection sensor, and also provide an ink jet recording device capable of executing such flushing timing adjustment.
A flushing timing adjustment method according to an aspect of the present invention is a flushing timing adjustment method of an inkjet recording device for adjusting a flushing timing which is an ink discharge timing for flushing to discharge ink from a recording head toward openings of an endless conveyance belt. The adjustment method includes detecting a recording medium supplied from a recording medium supply portion to the conveyance belt by a recording medium detection sensor, detecting the recording medium conveyed by the conveyance belt by an opening detection sensor that detects the openings that move by running of the conveyance belt, recording a first chart on the recording medium by discharging ink from a predetermined nozzle of the recording head at a plurality of discharge timings set in advance using a detection time point at which the recording medium is detected by the recording medium detection sensor as a reference time point, and recording a second chart on the recording medium alongside the first chart by discharging ink from another nozzle of the recording head at a plurality of discharge timings set in advance using a detection time point at which the recording medium is detected by the opening detection sensor as a reference time point, and adjusting the flushing timing in accordance with the an input of an instruction following the recording of the first chart and the second chart are recorded on the recording medium, the flushing timing being set using the detection time point at which the opening is detected by the opening detection sensor as a reference time point.
An inkjet recording device according to another aspect of the present invention includes a recording head having a plurality of nozzles for discharging ink, an endless conveyance belt that conveys a recording medium and has openings at a plurality of locations in the conveyance direction of the recording medium, the plurality of openings allowing ink to pass through when the recording head executes flushing for discharging ink at timing different from timing that contributes to image formation, a recording medium supply portion that supplies the recording medium to the conveyance belt, a recording medium detection sensor that detects the recording medium supplied from the recording medium supply portion to the conveyance belt, an opening detection sensor that detects the openings that move by running of the conveyance belt, and also detects the recording medium on the conveyance belt, and a discharge control portion that controls discharging of the ink in the recording head. The discharge control portion causes a first chart to be recorded on the recording medium by discharging ink from a predetermined nozzle of the recording head at a plurality of discharge timings set in advance using a detection time point at which the recording medium is detected by the recording medium detection sensor as a reference time point, and causes a second chart to be recorded on the recording medium alongside the first chart by discharging ink from another nozzle of the recording head at a plurality of discharge timings set in advance using a detection time point at which the recording medium is detected by the opening detection sensor as a reference time point.
The flushing timing, which is set using the detection time point of the openings by the opening detection sensor as the reference time point, is adjusted in accordance with the input of the instruction following the recording of the first chart and the second chart on the recording medium. When the flushing is performed during the use of the device on the user side, the ink can be discharged from the recording heads at the pre-adjusted flushing timing and passes through the openings of the conveyance belt, even though the opening detection sensor has the tolerance (detection tolerance, installation position tolerance). Therefore, it is possible to perform the flushing accurately without enlarging the openings unnecessarily to reduce the effect of the tolerance. Furthermore, the inkjet recording device capable of such flushing timing adjustment can be implemented.
An embodiment of the present invention will be described below with reference to the accompanying drawings.
A paper feeder 3 is disposed on a downstream side of the paper-feed cassette 2 in a paper conveyance direction, that is, on an upper right side of the paper-feed cassette 2 in
The printer 100 includes a first paper conveyance path 4a therein. The first paper conveyance path 4a is located on the upper right side of the paper-feed cassette 2 in the paper-feed direction. The paper P, which is fed out of the paper-feed cassette 2, is conveyed perpendicularly upward along the first paper conveyance path 4a on a side surface of the printer body 1.
A registration roller pair 13 is provided at a downstream end of the first paper conveyance path 4a in the paper conveyance direction. In addition, a first conveyance unit 5 and a recording portion 9 are disposed in the immediate vicinity on a downstream side of the registration roller pair 13 in the paper conveyance direction. The paper P is fed out of the paper-feed cassette 2 and reaches the registration roller pair 13 through the first paper conveyance path 4a. The registration roller pair 13 measures timing for an ink discharge operation executed by the recording portion 9 while correcting diagonal feed of the paper P, and feeds the paper P toward the first conveyance unit 5 (particularly to a first conveyance belt 8 which will be described later). That is, the registration roller pair 13 is a recording medium supply portion that supplies the paper P onto the first conveyance belt 8.
The paper P fed to the first conveyance unit 5 by the registration roller pair 13 is conveyed by the first conveyance belt 8 to a position facing the recording portion 9 (in particular, recording heads 17a to 17c, which will be described below). Ink is discharged onto the paper P from the recording portion 9 to record an image on the paper P. The ink discharge in the recording portion 9 is controlled by a controller 110 in the printer 100.
In the paper conveyance direction, a second conveyance unit 12 is disposed on a downstream side (left side in
In the paper conveyance direction, a de-curler portion 14 is provided on the downstream side of the second conveyance unit 12 and near the left side of the printer body 1. The paper P, on which the ink has been dried by the second conveying portion 12, is conveyed to the de-curler portion 14 to uncurl the curling of the paper P.
In the paper conveyance direction, a second paper conveyance path 4b is provided on the downstream side (upper side in
A reverse conveyance path 16 for the double-sided recording is provided at an upper portion of the printer body 1 and above the recording portion 9 and the second conveyance unit 12. In a case where the double-sided recording is performed, the paper P, on which recording is completed on one surface (first surface) thereof and which has passed through the second conveyance unit 12 and the de-curler portion 14, is conveyed to the reverse conveyance path 16 through the second paper conveyance path 4b.
The conveyance direction of the paper P, which has been conveyed to the reverse conveyance path 16, is switched for subsequent recording on the other surface (second surface) of the paper P. Then, the paper P passes through the upper portion of the printer body 1 to proceed rightward, and is conveyed to the first conveyance unit 5 again via the registration roller pair 13 with the second surface thereof faces upward. In the first conveyance unit 5, the paper P is conveyed to the position facing the recording portion 9, and the ink is discharged from the recording portion 9 to the second surface to record the image thereon. After the double-sided recording is performed, the paper P is discharged to the paper discharge tray 15 through the second conveyance unit 12, the de-curler portion 14, and the second paper conveyance path 4b in this order.
A maintenance unit 19 and a cap unit 20 are provided below the second conveyance unit 12. The maintenance unit 19 moves horizontally below the recording portion 9 in execution of purging, wipes the ink pushed out of ink discharge port of the recording head, and collects the wiped ink. Purging refers to an operation to forcibly push out the ink from the ink discharge port of the recording head in order to discharge thickened ink, a foreign substance, or air bubbles in the ink discharge ports. The cap unit 20 moves horizontally toward the position below the recording portion 9 when capping the ink discharge surface of the recording head, then farther moves upward and is mounted on a lower surface of the recording head.
The line heads 11Y to 11K each have a plurality of (three in this case) recording heads 17a to 17c. The recording heads 17a to 17c are arranged in a staggered manner along a paper width direction (arrow BB′ direction) perpendicular to the paper conveyance direction (the arrow A direction). Each of the recording heads 17a to 17c has a plurality of ink discharge ports 18 (nozzles). The ink discharge ports 18 are arranged at equally-spaced intervals in a width direction of the recording head, that is, the paper width direction (arrow BB′ direction). The inks of yellow (Y), magenta (M), cyan (C), and black (K) colors are discharged respectively onto the paper P that is conveyed on the first conveyance belt 8 from each of the line heads 11Y to 11K via the ink discharge ports 18 of the recording heads 17a to 17c.
The registration sensor 21 detects the paper P that is conveyed from the paper-feed cassette 2 by the paper feeder 3 and is fed to the registration roller pair 13. The registration sensor 21 is located on the upstream side of the registration roller pair 13 in a paper supply direction of the paper P. A paper supply control portion 110b, which will be described later, of the controller 110, can control a rotation start timing of the registration roller pair 13 in accordance with the detection result of the registration sensor 21. For example, the paper supply control portion 110b can control the paper supply timing of the paper P to the first conveyance belt 8 after skew correction by the registration roller pair 13 in accordance with the detection result of the registration sensor 21.
The paper detection sensor 22 is a recording medium detection sensor that detects the passage (timing) of a leading edge of the paper P fed from the registration roller pair 13 to the first conveyance belt 8. The paper detection sensor 22 is located on the upstream side of the opening detection sensor 23 in the paper conveyance direction. In accordance with the detection result of the paper P by the paper detection sensor 22, the discharge control portion 110a can control the ink discharge timing for the paper P that reaches the position facing line heads 11Y to 11K (recording heads 17a to 17c) by the first conveyance belt 8.
The opening detection sensor 23 detects openings 80 (see
The belt sensor 24 detects the position of an opening group 82 (openings 80) which is used as a reference during conveyance of the paper among a plurality of opening groups 82 of the first conveyance belt 8. For example, a marker may be attached on the first conveyance belt 8 at a position corresponding to the reference opening group 82, so that the belt sensor 24 can detect the reference opening group 82 by detecting the marker.
The belt sensor 24 is located on the upstream side of the driven roller 6b on which the first conveyance belt 8 stretches in the paper conveyance direction (running direction of the first conveyance belt 8). Therefore, the belt sensor 24 may be located between the driven roller 6b and the other roller 7b, or between the rollers 7a and 7b. The driven roller 6b is located on the upstream side of the recording portion 9 in the running direction of the first conveyance belt 8. The paper supply control portion 110b can control the registration roller pair 13 such that the paper P is supplied to the first conveyance belt 8 at a predetermined timing in accordance with the detection result of the opening group 82 by the belt sensor 24.
The paper detection sensor 22, the opening detection sensor 23, and the belt sensor 24, which have been described above, can be provided as transmissive or reflective optical sensors, contact image (CIS) sensors, or the like. In particular, the opening detection sensor 23 is desirably provided as the optical sensor capable of detecting both regularly reflected light and the diffusely reflected light, the reasons for which will be described later.
Furthermore, the printer 100 may include a meandering detection sensor that detects meandering of the first conveyance belt 8 and correct the meandering of the first conveyance belt 8 in accordance with the detection result.
The printer 100 further includes an operation panel 27, a storage 28, and a communication portion 29.
The operation panel 27 is a control panel for accepting various types of input for setting. For example, the user can operate the operation panel 27 to enter information on the size of the paper P to be set in the paper-feed cassette 2, that is, the information on the size of the paper P to be conveyed by the first conveyance belt 8. The user can also operate the operation panel 27 to enter the number of sheets of the paper P to be printed or instruct to start print jobs.
The storage 28 is a memory that stores an operating program of the controller 110 and various types of information, and is configured to include a read only memory (ROM), a random access memory (RAM), a non-volatile memory, or the like. The storage 28 stores the information set using the operation panel 27 (for example, the information on the size of the paper P). The storage 28 also stores information on the position of each opening 80 of the first conveyance belt 8 and a pattern of the openings 80 through which ink is passed during the flushing which will be described later.
The communication portion 29 is a communication interface used to exchange information with an external device (for example, a personal computer (PC)). For example, when the user operates the PC to send a print command and image data to the printer 100, the image data and the print command are entered to the printer 100 via the communication portion 29. In the printer 100, the discharge control portion 110a controls the recording heads 17a to 17c in accordance with the image data to discharge ink to record the image on the paper P.
In view of the above, the operation panel 27 and communication portion 29 can also be regarded as functioning as an input accepting portion 30 that accepts input of various types of information.
The printer 100 of the present embodiment also includes the controller 110. The controller 110 is composed of, for example, a central processing unit (CPU), and includes the discharge control portion 110a, the paper supply control portion 110b, and the main control portion 110c. The discharge control portion 110a controls the discharge of ink from the recording heads 17a to 17c. The paper supply control portion 110b is a recording medium supply control portion that controls the registration roller pair 13 as the recording medium supply portion in accordance with the detection result of the opening group 82 by the belt sensor 24, thus controlling the supply of the paper P to the registration roller pair 13. The main control portion 110c controls the operation of individual parts in the printer 100. The discharge control portion 110a, the paper supply control portion 110b, and the main control portion 110c may further function as an arithmetic portion that performs necessary calculations and as a timekeeping portion that measures time.
Furthermore, as illustrated in
Here, the flushing means the discharge of ink from the ink discharge ports 18 at timing different from timing that contributes to the image formation (image recording) on the paper P for the purpose of reducing or preventing clogging of the ink discharge ports 18 caused by drying of the ink. The discharge control portion 110a controls the execution of flushing in the recording heads 17a to 17c.
The above-described second conveyance unit 12 includes a second conveyance belt 12a and a dryer 12b. The second conveyance belt 12a stretches over two drive rollers 12c and a driven roller 12d. The paper P, which is conveyed by the first conveyance unit 5, and on which the image is recorded by the ink discharge by the recording portion 9, is conveyed by the second conveyance belt 12a, dried by the dryer 12b during the conveyance, and is then conveyed to the de-curler portion 14.
Next, the first conveyance belt 8 in the first conveyance unit 5 is described in detail below.
The first conveyance belt 8 also includes the opening groups 82. The opening groups 82 is a group of the openings 80 to allow the ink discharged from the nozzles (ink discharge ports 18) of the recording heads 17a to 17c to pass through during flushing. An opening area of one opening 80 is larger than an opening area of one suction hole 8a. The first conveyance belt 8 includes a plurality of opening groups 82 in one cycle of conveying the paper P in the conveyance direction of the paper P (direction A), and six group are provided in the present embodiment. One cycle means a period in which the first conveyance belt 8 makes one round. To distinguish the opening groups 82 from each other, the six opening groups 82 are referred to as opening groups 82A to 82F from the downstream side in the direction A. The suction holes 8a are located between adjacent opening groups 82 in the direction A. That is, in the first conveyance belt 8, no suction holes 8a are formed in an area overlapping the opening groups 82 (around the openings 80).
In one cycle of the first conveyance belt 8, the opening groups 82 are irregularly located in the direction A. That is, in the direction A, a distance between adjacent opening groups 82 is not constant but varies. At this time, the maximum distance between the two adjacent opening groups 82 in the direction A (for example, a distance between the opening group 82A and the opening group 82B in
Each opening group 82 includes opening rows 81. Each opening row 81 is formed by arranging the plurality of openings 80 in the belt width direction (paper width direction, direction BB′) perpendicular to the direction A. One opening group 82 includes at least one opening row 81 in the direction A, and two opening rows 81 are provided in the present embodiment. To distinguish the two opening rows 81 from each other, it is assumed that one of them is an opening row 81a, and the other is an opening row 81b.
In one opening group 82, the openings 80 in any one of the opening rows 81 (for example, the opening row 81a) are shifted in the direction BB′ from the openings 80 in the other opening row 81 (for example, the opening row 81b), and are arranged so as to partially overlap the openings 80 in the other opening row 81 (for example, the opening row 81b) when viewed in the direction A. In each opening row 81, the plurality of openings 80 are located at equally-spaced intervals in the direction BB′.
Since the plurality of opening rows 81 are arranged in the direction A to form one opening group 82 as described above, a width of the opening group 82 in the direction BB′ is greater than a width of the recording heads 17a to 17c in the direction BB′. This means that each opening group 82 covers an entire ink discharge area in the direction BB′ of the recording heads 17a to 17c, and the ink discharged from all the ink discharge ports 18 of the recording heads 17a to 17c during flushing passes through any one of the openings 80 in the opening group 82.
In view of the above, the first conveyance belt 8 can be regarded as including the opening groups 82 each including the openings 80 through which the ink discharged from the recording heads 17a to 17c passes during flushing at the plurality of locations at different intervals in the direction A which is the conveyance direction.
In the present embodiment, the discharge control portion 110a controls the recording heads 17a to 17c to record images on the paper P, while the paper P is conveyed using the first conveyance belt 8, in accordance with the image data transmitted from the outside (for example, the PC). At this time, the recording heads 17a to 17c are made to perform the flushing between the sheets of paper P that are conveyed (flushing between the papers) to reduce or prevent clogging of the ink discharge ports 18.
Here, in the present embodiment, the discharge control portion 110a determines a pattern (combination) of the plurality of opening groups 82 in the direction A used in the flushing in one cycle of the first conveyance belt 8, based on the size of the paper P to be used. The size of the paper P to be used can be recognized by the discharge control portion 110a in accordance with the information stored in the storage 28 (information on the size of the paper P entered by the operation panel 27a) or the image data transmitted with an externally entered printing command. The pattern of the opening groups 82 is literally distinguished from a placement pattern of the paper P, which will be described later.
The discharge control portion 110a then causes the recording heads 17a to 17c to execute flushing at the timing when the opening groups 82 located according to the determined pattern brought to face the recording heads 17a to 17c by the running of the first conveyance belt 8. Here, the running speed of the first conveyance belt 8 (paper conveyance speed) and the positional relationship of the recording heads 17a to 17c and the opening detection sensor 23 relative to the first conveyance belt 8 are known in advance. Accordingly, when the opening detection sensor 23 detects that the first conveyance belt 8 runs and passes the openings 80 of a predetermined opening group 82, how many seconds after the detection time point the predetermined opening group 82 passes the position facing the recording heads 17a to 17c is known. Therefore, the discharge control portion 110a can cause the recording heads 17a to 17c to execute flushing so that the ink passes through the openings 80 of the opening group 82 located in the pattern determined above by having the recording heads 17a to 17c discharge ink at the discharge timing determined in accordance with the detection result of the openings 80 by the opening detection sensor 23.
The paper supply control portion 110b controls the supply of the paper P to the first conveyance belt 8 by the registration roller pair 13 such that the paper P is displaced in the direction A from the opening group 82 located in the pattern determined above. In other words, the paper supply control portion 110b causes the registration roller pair 13 to supply the paper P between the plurality of opening groups 82 lined up in the direction A in the above pattern on the first conveyance belt 8.
For example, when the paper P to be used is A4 size (landscape) or letter size (landscape), the paper supply control portion 110b, the registration roller pair 13 is controlled such that, as illustrated in
Here, the paper supply control portion 110b can determine the timing for supplying the paper P by the registration roller pair 13 in accordance with the detection result of the predetermined opening group 82 by the belt sensor 24. For example, when the belt sensor 24 detects that the first conveyance belt 8 runs and pass the reference opening group 82 (for example, the opening group 82A), the paper supply control portion 110b can determine how many seconds after the detection time point the paper P should be supplied to the first conveyance belt 8 by the registration roller pair 13 to place the paper P at respective positions illustrated in
When the paper P to be used is A4 size (portrait) or letter size (portrait), the paper supply control portion 110b controls the registration roller pair 13 to supply the paper P to the first conveyance belt 8 at a predetermined supply timing such that two sheets of paper P are placed between the opening groups 82A and 82D and between the opening group 82D and the opening group 82A of the next cycle on the first conveyance belt 8, as illustrated in
When the paper P to be used is A3 size, B4 size or legal size (all in portrait), the paper supply control portion 110b controls the registration roller pair 13 to supply the paper P to the first conveyance belt 8 at a predetermined supply timing such that one sheet of paper P is placed between the opening groups 82A and 82B, one sheet of paper P is placed between the opening groups 82B and 82E, and one sheet of paper P is placed between the opening group 82E and the opening group 82A of the next cycle on the first conveyance belt 8, as illustrated in
When the paper P to be used is 13″×19.2″ in size, the paper supply control portion 110b controls the registration roller pair 13 to supply the paper P to the first conveyance belt 8 at a predetermined supply timing such that one sheet of paper P is placed between the opening groups 82A and 82D, and one sheet of paper P is placed between the opening group 82D and the opening group 82A of the next cycle on the first conveyance belt 8, as illustrated in
Thus, as illustrated in
Here, the supply speed of the paper P (running speed of the first conveyance belt 8), and the positional relationship between the recording heads 17a to 17c and the paper detection sensor 22 are known in advance. Therefore, when the paper detection sensor 22 detects the passage of the paper P, how many seconds after the detection time point the paper P passes the positions facing the recording heads 17a to 17c is known. Therefore, the discharge control portion 110a causes the ink to be discharged from the recording heads 17a to 17c at the discharge timing determined in accordance with the detection result of the paper P by the paper detection sensor 22, so that the ink discharged from the recording heads 17a to 17c lands on the paper P and the image is recorded on the paper P.
In normal printing, as described in (2-3) above, the discharge control portion 110a causes the ink to be discharged from the recording heads 17a to 17c at the first discharge timing determined in accordance with the detection time point when the paper P is detected by the paper detection sensor 22. Here, it is assumed that the first discharge timing is set, for example, at the time when time T1 (unit: second) has elapsed after the detection time point of the paper P by the paper detection sensor 22. When executing flushing, as described in (2-2) above, the discharge control portion 110a causes the ink to be discharged from the recording heads 17a to 17c at the second discharge timing determined in accordance with the detection time point of the openings 80 by the opening detection sensor 23. Here, it is assumed that the second discharge timing is set, for example, at the time when time T2 (unit: second) has elapsed after the detection time point of the paper P 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 portion 9), T1>T2 is satisfied.
The second discharge timing mentioned above varies for each device (printer 100), depending on the detection tolerance and the installation tolerance of the opening detection sensor 23. To facilitate handling of such variations in the second discharge timing from device to device, the second discharge timing is adjusted by means described later for each device in the present embodiment. Before describing the adjustment of the second discharge timing or the flushing timing, the opening detection sensor 23 described above used to adjust the flushing timing is described in details.
In the present embodiment, an optical analog sensor (optical sensor) that detects both regularly reflected light and diffusely reflected light is used as the opening detection sensor 23. Such an optical sensor is also called an image density sensor (ID sensor).
As illustrated on the left-hand side of
On the other hand, as illustrated on the right-hand side of
Thus, by using the ID sensor that detects the reflected light and the diffusely reflection light as the opening detection sensor 23, the controller 110 (for example, the discharge control portion 110a) can determine, in accordance with the output signal from the opening detection sensor 23, whether the object passing through the position facing the opening detection sensor 23 is (i) the first conveyance belt 8, (ii) the opening 80 of the first conveyance belt 8, or (iii) the paper P on the first conveyance belt 8. The output signal gain may be adjusted according to the sensitivity of the first and second light receiving portions 23b and 23 of the opening detection sensor 23, so that the controller 110 can clearly distinguish the above three states.
Next, a flushing timing adjustment method using the opening detection sensor 23 described above is described.
First, for example, in the factory settings of the device (printer 100), an operator involved in manufacturing the device operates the operation panel 27 to select a flushing timing adjustment mode (S1). This selection of the mode allows the opening detection sensor 23, which normally detects the openings 80 moved by the running of the first conveyance belt 8, to be used as a sensor to detect the paper P, and allows the ink to be discharged from the recording heads 17a to 17c in accordance with the detection of the paper P by the opening detection sensor 23.
Next, when the paper detection sensor 22 detects the paper P fed to the first conveyance belt 8 by the registration roller pair 13 (S2), and the opening detection sensor detects the paper P conveyed by the first conveyance belt 8 (S3), the discharge control portion 110a controls the discharge of the ink by the recording heads 17a to 17c to record a check pattern (first chart, second chart) on the paper P (S4).
Specifically, in S4, the discharge control portion 110a causes the recording heads 17a to 17c to discharge inks from predetermined nozzles (ink discharge ports 18) at a plurality of predetermined discharge timings set in advance using the detection time point t0 of paper P as a reference time point by the paper detection sensor 22 to record a first chart C1 on the paper P. The discharge control portion 110a also causes the recording heads 17a to 17c to discharge ink from other nozzles at the plurality of discharge timings set in advance using the detection time point t2 of the paper P by the opening detection sensor 23 as the reference time point, thus recording the second chart C2 on the paper P alongside the first chart C1.
In the drawing, “A to I, 0 to 9” are signs given for convenience corresponding to each position of the first reference line Cr1 and the plurality of first auxiliary lines Cs1. Of these signs, the sign “0” corresponds to the position of the first reference line Cr1, and the signs “A-I, 1 to 9” correspond to the positions of the first auxiliary line Cs1. In particular, the signs “1 to 9” are given to the first auxiliary lines Cs1 located on the upstream side of the first reference line Cr1 in this order upstream from the first reference line Cr1. The signs “A to I” are given to the first auxiliary lines Cs1 located on the downstream side of the first reference line Cr1 in this order downstream from the first reference line Cr1.
It is assumed that the interval between the discharges of ink to form the first reference line Cr1 and the plurality of the first auxiliary lines Cs1 is, for example, 50 μsec. Therefore, using the discharge timing of the first reference line Cr1 as a reference timing, the ink discharge timing for forming each line of the first chart C1 is, for example, T1−50 (μsec), T1−50×2 (ρsec), T1−50×3 (μsec), . . . , upstream from the first reference line Cr1, and, for example, T1+50 (μsec), T1+50×2 (μsec), T1+50×3 (μsec), . . . , downstream from the first reference line Cr1.
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 a line formed by the ink discharged at a reference discharge timing (for example, after time T2 has elapsed from the detection point t2 of the paper P by the opening detection sensor 23) from other nozzles of the recording heads 17a to 17c in accordance with the detection of the paper P by the opening detection sensor 23. The second auxiliary lines Cs2 are lines formed by the ink discharged at a plurality of timings before and after the reference discharge timing from the other nozzles. The plurality of the second auxiliary lines Cs2 are lined up with the second reference line Cr2 on the paper P in the conveyance direction of 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.
It is assumed that the ink discharge interval to form the second reference line Cr2 and the plurality of the second auxiliary lines Cs2 is, for example, 60 μsec. Therefore, using the discharge timing of the second reference line Cr2 as a reference discharge timing, the ink discharge timing to form the lines of the second chart C2 is, for example, T1−60 (μsec), T1−60×2 (μsec), T1−60×3 (μsec), . . . , upstream from the second reference line Cr2, and, for example, T1+60 (μsec), T1+60×2 (μsec), T1+60×3 (μsec), . . . , downstream from the second reference line Cr2.
Thus, the ink discharge interval to form the lines is different between the first chart C1 and the second chart C2. Therefore, an interval D1 between all lines included in the first chart C1 in the conveyance direction of the paper P (first reference line Cr1, first auxiliary lines Cs1) is different from a distance D2 between all lines included in the second chart C2 (second reference line Cr2, second auxiliary lines Cs2) in the conveyance direction of the paper P. For example, D1<D2 is satisfied in the present embodiment.
Once the check pattern illustrated in
Thus, when the operator sees the paper P on which the check pattern is recorded in S4 and determines that both ink discharge timings match up (No in S5), there is no need to change the flushing timing, and the operator operates the operation panel 27 to enter the end of the flushing timing adjustment (S6). In this case, the discharge control portion 110a sets (maintains), as the flushing timing, the reference discharge timing immediately before the end of the flushing timing adjustment, that is, the ink discharge timing to form the second reference line Cr2 (after time T2 from the detection time point), in accordance with the detection time point t1 of the openings 80 by the opening detection sensor 23, and stores the flushing timing in the storage 28.
When the flushing is executed in the installation environment on the user side after shipment of the device, the discharge control portion 110a causes the nozzles of the recording heads 17a to 17c to discharge ink after time T2 has elapsed from the detection time point t1 of the opening 80 by the opening detection sensor 23. With the flushing timing set as described above, the ink discharged from the recording heads 17a to 17c can pass through the openings 80.
When the normal printing is performed in the installation environment on the user side, the discharge control portion 110a can allow the image to be recorded on the paper P by discharging the ink from the recording heads 17a to 17c after time T1 has elapsed from the detection time point t0, using the detection time point t0 when the paper P is detected by the paper detection sensor 22 as the reference time point.
On the other hand,
Thus, when the operator sees the paper P on which the check pattern is recorded in S4 and determines that there is a discrepancy between the ink discharge timing based on the paper detection by the paper detection sensor 22 and the ink discharge timing based on the paper detection by the opening detection sensor 23 (Yes at S5), the flushing timing needs to be changed, and the operator operates the operation panel 27 to enter the flushing timing adjustment value (S8). For example, in the example of
Thus, the discharge control portion 110a changes the ink discharge timing to form the lines of the second chart C2 according to the discrepancy amount. For example, the discharge control portion 110a changes the ink discharge timing to form the second reference line Cr2 from “after time T2 from the detection time point of the openings 80 by the opening detection sensor 23” to “after time T2′ from the detection time point of the openings 80 by the opening detection sensor 23”. In the above example, T2′ (sec)=T2 (sec)+250 (μsec)=T2+0.25 (sec). In addition, the discharge control portion 110a changes the ink discharge timing to form the plurality of second auxiliary lines Cs2 by back calculation in accordance with the ink discharge timing (after the change) to form the second reference line Cr2. The process then returns to S2 and repeats the process from S2 onward.
Subsequently, if the operator sees the paper P with the check pattern recorded in S4 and there is a discrepancy between the ink discharge timing based on the paper detection by the paper detection sensor 22 and the ink discharge timing based on the paper detection by the opening detection sensor 23, the operator enters 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 discrepancy, the operator proceeds to S6 and operates the operation panel 27 to enter the end of flushing timing adjustment. In this case, the discharge control portion 110a sets, as the flushing timing, the reference discharge timing immediately before the end of the flushing timing adjustment, that is, the ink discharge timing to form the second reference line Cr2 (after time T2′ from the detection time point of the openings 80 by the opening detection sensor 23), in accordance with the detection time point of the openings 80 by the opening detection sensor 23), and stores the flushing timing in the storage (S7).
When executing the flushing in the installation environment on the user side after the device is shipped, the discharge control portion 110a causes the ink to be discharged from the nozzles of the recording heads 17a to 17c after time T2′ has elapsed from the detection time point t1 of the openings 80 by the opening detection sensor 23. As a result, the ink discharged from the recording heads 17a to 17c at the adjusted flushing timing passes through the openings 80 in the first conveyance belt 8.
The example of adjusting the flushing timing for any one of the openings 80 in each of the opening groups 82 has been described above, but as in the present embodiment, in the structure in which the openings 80 of each opening group 82 are arranged in the staggered manner, a time difference in flushing timing needs to be provided between the first row (for example, the opening row 81a) and the second row (for example, the opening row 81b) of each opening group 82. The positional information of the openings 80 of one opening group 82 (positional information of the openings 80 of the opening row 81a and openings 80 of the opening row 81b) is stored in the storage 28 in advance, and the running speed of the first conveyance belt 8 is constant, so that the above time difference can be obtained by calculation.
For example, when the flushing timing for the openings 80 of the opening row 81a is set (maintained or changed) in the above manner, the flushing timing for the openings 80 of the next opening row 81b can be set (maintained or changed) by adding the above time difference to the flushing timing for the openings 80 of the opening row 81a. By causing the ink to be discharged from the corresponding nozzles of the recording heads 17a to 17c at the flushing timing set above, it is possible to execute flushing to allow the ink to pass through the openings 80 of opening row 81b.
As described above, the present embodiment uses the opening detection sensor 23, which originally detects the openings 80, as a sensor to detect the paper P, thus discharging the ink at the timing in accordance with the detection of the paper P by the paper detection sensor 22 to record the first chart C1 on the paper P, while recording the second chart C2 on the paper P by discharging the ink at the discharge timing in accordance with the detection of the paper P by the opening detection sensor 23 (S2 to S4). After the first chart C1 and the second chart C2 are recorded on the paper P, the flushing timing, which is set using the detection time point of the openings 80 by the opening detection sensor 23, is adjusted in accordance with the input of instruction from the operation panel 27 (S6 to S8). The flushing timing adjustment may include changing the flushing timing in accordance with the input of the adjustment value in S8, and also include maintaining the initial setting of the flushing timing without change in accordance with the input of the end of adjustment in S6.
By recording the first chart C1 and the second chart C2 on the paper P as described above, the operator who is involved in the manufacturing of the device can see the first chart C1 and the second chart C2 to easily determine whether the ink discharge timing based on the detection by the opening detection sensor 23 matches the normal timing. In other words, the operator can easily determine whether the ink discharge timing during flushing in accordance with the detection of opening 80 by the opening detection sensor 23 is correct (whether the discharged ink can pass through the openings 80) by comparing the image (second chart C2) obtained by actually discharging ink onto the paper P at the timing based on the detection of paper P by the opening detection sensor 23 (second chart C2) and another image (first chart C1) obtained by discharging ink at the timing based on the detection of the paper P by another sensor (paper detection sensor 22). The operator can then enter the instruction to adjust (change or maintain) the flushing timing in accordance with the determination result.
In addition, the user of the manufactured printer 100 can also recognize the state of the printer 100 by letting the printer 100 to record the check pattern (first chart C1 and second chart C2).
When the user feels that the printer 100 may be malfunctioning, the user can operate the operation panel 27 to have the check pattern recorded. The user can find information about recording such check patterns from the help screen stored in the storage 28 and displayed on the operation panel 27 or in the manuals that come with the printer 100. By viewing the check pattern according to the help screen or the manuals, the user can determine the state of the printer 100 with respect to the ink discharge timing during flushing. Alternatively, the user can send the check pattern to the manufacturer, the distributor, or the like of the printer 100 to check the state of the printer 100.
When the check pattern indicates that the printer 100 should be adjusted, the user may adjust the flushing timing in the same way as the operator described above, or may ask someone who manufactured or sold the printer 100 to make the adjustment.
The main control portion 110c may record the check pattern at predetermined intervals to allow the user to check the state of the printer 100. The interval between recordings may be by the number of sheets printed or by time, such as the elapsed time or the operating time of the printer 100. Instead of recording the check pattern, the main control portion 110c may cause the operation panel 27 to display to urge recording of the check pattern at predetermined intervals.
On the device side, the flushing timing is adjusted for each device in accordance with the input of the instruction. Even when the opening detection sensor 23 has the tolerance (detection tolerance, installation position tolerance), the ink can be discharged from the recording heads 17a to 17c at an appropriate flushing timing for each device and made to accurately pass through the openings 80 to execute the flushing in the installation environment on the user side after the device is shipped. This eliminates the need to form larger openings 80 in the first conveyance belt 8 to reduce the effect of the tolerance of the opening detection sensor 23. As a result, the following effects can further be obtained.
Specifically, the size of the openings 80 can be kept to the minimum necessary, thus suppressing the decrease of the strength of the first conveyance belt 8. Even when the paper P is placed to overlap the openings 80 that are not used for flushing on the first conveyance belt 8 during the normal image formation, the deflection of the paper P toward the inside of the openings 80 can be suppressed due to the small size of the openings 80. Thus, the degradation in quality of the recorded image caused by the deflection of the paper P can be suppressed.
Since the effect of the tolerance of the opening detection sensor 23 is reduced, it is possible to expand the design margin of the device regarding the installation and assembly of the components including the opening detection sensor 23.
According to the flushing timing adjustment method of the present embodiment, the flushing timing can be easily adjusted in accordance with the input of instruction by the operator, thus simplifying the work required for the adjustment.
In particular, in S6, the flushing timing is adjusted in accordance with the adjustment value entered after the first chart C1 and the second chart C2 are recorded on the paper P. This makes it possible to change the flushing timing appropriately in accordance with the adjustment value.
The first chart S1 includes the first reference line Cr1 and the second chart S2 includes the second reference line Cr2. By recording the first chart C1 and the second chart C2 on the paper P, the operator can easily recognize whether there is a discrepancy between the ink discharge timing based on the detection of the paper P by the paper detection sensor 22 and the ink discharge timing based on the detection of the paper P by the opening detection sensor 23 in accordance with the positional discrepancy between the first reference line Cr1 of the first chart C1 and the second reference line Cr2 of the second chart C2 in the conveyance direction of the paper P. Therefore, the operator can easily determine whether it is necessary to adjust the flushing timing (ink discharge timing based on the detection of the openings 80 by the opening detection sensor 23).
The first chart C1 further includes the plurality of the first auxiliary lines Cs1, and the second chart C2 further includes the plurality of the second auxiliary lines Cs2. In this case, the operator can recognize and recognize easily the amount of discrepancy between the first reference line Cr1 of the first chart C1 and the second reference line Cr2 of the second chart C2 in the paper P conveyance direction by corresponding it to the time interval between the first reference line Cr1 and the first auxiliary line Cs1 formed by matching the discharge timing with the second reference line Cr2. Specifically, in the example of
The interval D1 between all lines of the first chart C1 in the conveyance direction of the paper P is different from the interval D2 between all lines of the second chart C2 in the conveyance direction of the paper P (see
The opening detection sensor 23 is the optical sensor that detects both the regularly reflected light and the diffusely reflected light. By using such an opening detection sensor 23, the discharge control portion 110a can reliably distinguish and recognize whether the detection target is the first conveyance belt 8 (area on which the paper P is not placed), the openings 80 of the first conveyance belt 8, or the paper P on the first conveyance belt 8, in accordance with the output signals from the opening detection sensor 23, that is, the detection signal of the regularly reflected light and the detection signal of the diffusely reflected light. This ensures the implementation of the flushing timing adjustment method described above using the opening detection sensor 23. The ID sensor that detects both the regularly reflected light and the diffusely reflected light can be used as the opening detection sensor 23, thus effectively utilizing the ID sensor.
The opening detection sensor 23 may be a reflective optical sensor that detects the regularly reflected light. The reflective optical sensor outputs the detection signal such as the output 1 illustrated in
In the example described above, the operator directly operates the operation panel 27 to enter the instruction on the flushing timing (enter the instruction to end the adjustment or enter the adjustment value). Alternatively, the operator may enter the instructions on the PC. In this case, the device (printer 100) receives the input of the instruction via the communication portion 29, and the flushing timing is adjusted on the device side in accordance with the input of the instruction.
According to the above description, the inkjet recording device (printer 100) that is directly used to implement the flushing timing adjustment method described above can be expressed as below. Specifically, the inkjet recording device includes the recording heads 17a to 17c each having the plurality of nozzles, the endless first conveyance belt 8 that conveys the paper P and includes the openings 80 at the plurality of locations in the conveyance direction of the paper P, the ink passing through the openings 80 during the execution of the flushing to discharge the ink at the timing different from the timing at which the recording heads 17a to 17c contribute to the image formation, the registration roller pair 13 that supplies the paper P to the first conveyance belt 8, the paper detection sensor 22 that detects the paper P to be supplied to the first conveyance belt 8 through the registration roller pair 13, the opening detection sensor 23 that detects the openings 80 that move by the running of the first conveyance belt 8 and detects the paper P on the first conveyance belt, and the discharge control portion 110a that controls the ink discharge by the recording heads 17a to 17c. The discharge control portion 110a causes the ink to be discharged from the predetermined nozzles of the recording heads 17a to 17c at the plurality of discharge timings set in advance using the detection time point of the paper P by the paper detection sensor 22 as the reference time point to record the first chart C1 on the paper P, while causing the ink to be discharged from other nozzles of the recording heads 17a to 17c at the plurality of discharge timings set in advance using the detection time point of the paper P by the opening detection sensor 23 as the reference time point to record the second chart C2 alongside the first chart C1 on the paper P. The printer 100 further includes the input accepting portion 30 (operation panel 27, communication portion 29) that accepts the input of the instruction for the flushing timing adjustment which indicates the timing for discharging the ink when the recording heads 17a to 17c execute the flushing. The discharge control portion 110a adjusts the flushing timing set by using the detection time point of the openings 80 by the opening detection sensor 23 as the reference time point, in accordance with the input of instruction accepted by the input accepting portion 30.
In the printer 100 according to the present embodiment, as illustrated in
For example, as illustrated in
By identifying the flushing executable timing by the discharge control portion 110a, the ink can be discharged, in the actual execution of the flushing, from the recording heads 17a to 17c at least at one identified flushing executable timing to pass through the openings 80 that do not overlap the paper P. Thus, the flushing can be performed with accuracy.
Even when the supply of the paper P to the first conveyance belt 8 is controlled such that the paper P is shifted from the opening groups 82A, 82C, and 82F on the first conveyance belt 8, it may be possible that the conveyance of the paper P is delayed for some reason (for example, slippage on the surface of the rollers on the way to the first conveyance belt 8) and the paper P is placed on top of the openings 80 of opening groups 82A, 82C, and 82F. In this case, the flushing executable timing is identified in the upstream vicinity of the recording heads 17a to 17c in accordance with the detection of the actual openings 80 and the paper P by the opening detection sensor 23. Therefore, the opening detection sensor 23 does not detect the openings 80 where the paper P overlaps the openings 80, and the timing when the recording heads 17a to 17c face such openings 80 is not identified as the flushing executable timing. This avoids the execution of flushing at the timing when such openings 80 face the recording heads 17a to 17c, and prevents soiling of the paper P overlapping the openings 80 with ink during flushing.
In a case where the paper P is placed overlapping the openings 80 to be flushed for some reason as described above, the discharge control portion 110a may avoid the flushing for such openings 80, or may also control to perform the following alternative measures (1) to (3).
(1) When the opening detection sensor 23 detects, subsequent to the paper P placed on top of the openings 80, openings 80 (openings 80 other than the openings 80 located in the pattern corresponding to the size of the paper P) that are not scheduled to perform the flushing, the discharge control portion 110a may cause the recording heads 17a to 17c to execute the flushing for such openings 80 (at the timing when such openings 80 are brought to face the recording heads 17a to 17c).
(2) The discharge control portion 110a may cause the recording heads 17a to 17c to execute the flushing (stir flushing) for the paper P that overlaps the openings 80 (at the timing when the paper P faces the recording heads 17a to 17c). In this case, it is desirable to discharge the ink in a dispersed manner to the paper P so as not to affect the quality of the recorded image on the paper P.
(3) The paper supply control portion 110b may control the registration roller pair 13 to delay the conveyance of the next paper P to be supplied, so that the openings 80 appear between the paper P that is placed on top of the openings 80 and the next paper P to be supplied. Then, the discharge control portion 110a may cause the recording heads 17a to 17c to execute the flushing for such openings 80 located between the two sheets of paper P (at the timing when the openings 80 face the recording heads 17a to 17c).
When the flushing is performed for the paper P, the main control portion 110c, for example, displays an error on the operation panel 27 to notify to the outside that such flushing has been performed. It may also be possible that, depending on the frequency that the paper P overlaps the openings 80 to be flushed, the paper supply control portion 110b may control the registration roller pair 13 to control the supply timing of the paper P and correct the placement position of the paper P on the first conveyance belt 8. In addition, the main control portion 110c may cause the operation panel 27 to display to urge cleaning of the first conveyance belt 8 according to the frequency, so as to reduce the possibility that the back side of the paper P (side that is in contact with the first conveyance belt 8) that overlaps the openings 80 is soiled with ink that is adhered around the openings 80.
In the above, the first conveyance belt 8 may be provided using the belt having the plurality of opening groups 82 which are irregularly positioned in the paper conveyance direction (the interval between the opening group 82 in the paper conveyance direction changes). Alternatively, a belt having the opening groups 82 or the openings 80 located at equally-spaced intervals in the paper conveyance direction and at intervals equal to or smaller than the length of the smallest size paper P in the paper conveyance direction. When using such a first conveyance belt 8, for example, the paper supply control portion 110b can control the registration roller pair 13 such that the plurality of sheets of paper P are placed on the first conveyance belt 8 at constant intervals and supply the sheets of paper P sequentially to the first conveyance belt 8 regardless of the positions of the openings 80 of the first conveyance belt 8. In this case, the discharge control portion 110a can also use the same method as above, that is, in accordance with the detection results of the openings 80 and the paper P by the opening detection sensor 23, identifying the flushing executable timing and causing the recording heads 17a to 17c to execute the flushing, thus obtaining the same effect as above.
If the plurality of flushing executable timings are identified, the discharge control portion 110a may cause the recording heads 17a to 17c to execute flushing at all of the identified flushing executable timings, or may cause the recording heads 17a to 17c to execute the flushing at some of the identified flushing executable timings. For example, the discharge control portion 110a may select the timing to actually discharge ink from the recording heads 17a to 17c from the plurality of flushing executable timings depending on the usage state of each nozzle of the recording heads 17a to 17c, and cause the recording heads 17a to 17c to execute flushing at the selected timing. In this case, the flushing can be executed by the recording heads 17a to 17c at the minimum necessary timings to obtain the effect of preventing nozzle clogging by flushing. The usage state of each nozzle may be determined by the discharge control portion 110a in accordance with, 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 the increase in ink consumption due to unnecessary flushing can be avoided.
As illustrated in
The opening detection sensor 23 used in the present embodiment is sized to detect one opening 80 (see
In the structure in which the printer 100 includes such a first conveyance belt 8 and an opening detection sensor 23, the discharge control portion 110a may perform the following control process. Specifically, in accordance with the position information of each opening 80 set in advance, the detection result of the opening 80 of the particular opening row 81a detected by the opening detection sensor 23, and the detection result of the paper P detected by the opening detection sensor 23, the discharge control portion 110a may determine whether there are the openings 80 that overlap with the paper P in the other opening row 81b of the opening group 82 to which the particular opening row 81a belongs and, in accordance with the determination result, identify the flushing executable timing for the openings 80 of the other opening row 81b.
For example, when it is determined that no paper P overlaps the other opening row 81b, the discharge control portion 110a may identify the ink discharge timing for the openings 80 of the other opening row 81b as the flushing executable timing. When it is determined that the paper P completely overlaps the openings 80 of the other opening row 81b, the discharge control portion 110a may exclude the ink discharge timing for the openings 80 of the other opening row 81b from the flushing executable timing. When it is determined that the paper P overlaps part of the openings 80 of the other opening row 81b, the discharge control portion 110a may identify the ink discharge timing for the remaining area of the opening row 81b (area that is not overlapped by the paper P) as the flushing executable timing.
In the first conveyance belt 8 in which the openings 80 are arranged in the staggered manner and the opening detection sensor 23 detects the openings 80 of the particular opening row 81a, even when the opening detection sensor 23 does not detect the openings 80 of the other opening row 81b, the discharge control portion 110a can determine whether the paper P is placed on top of the openings 80 of the other opening row 81b, in accordance with the position information of each opening 80, the detection result of the openings 80 in the particular opening row 81a, and the detection result of the paper P. Therefore, by setting the flushing executable timing in accordance with the determination result, the discharge control portion 110a can execute the flushing appropriately for the openings 80 of the other opening row 81b even though the opening detection sensor 23 does not detect the openings 80.
When it is determined that the paper P is shifted from the openings 80 of the other opening row 81b as described above, the discharge control portion 110a identifies the ink discharge timing for the openings 80 as the flushing executable timing. In this case, the discharge control portion 110a can perform the flushing for the openings 80 of the opening row 81b by causing the recording heads 17a to 17c to discharge ink at the identified flushing executable timing.
When it is determined that the paper P overlaps part of the openings 80 of the other opening row 81b, the discharge control portion 110a identifies the ink discharge timing for the remaining area of the openings 80 as the flushing executable timing. In this case, the discharge control portion 110a can perform the flushing for the area of the openings 80 of the opening row 81b where the paper P does not overlap by causing the recording heads 17a to 17c to discharge ink at the identified flushing executable timing. The discharge control portion 110a can determine whether the flushing is actually performed at the identified flushing executable timing.
When it is determined that there are the openings 80 of the opening row 81b that overlap with the paper P, it is desirable that the discharge control portion 110a stops the ink discharge from the recording heads 17a to 17c for the openings 80. In other words, it is desirable that the discharge control portion 110a excludes such an ink discharge timing for the openings 80 from the flushing executable timing. In this case, the ink is not discharged onto the paper P placed on top of the openings 80 during flushing according to the flushing executable timing, so that the possibility of soiling the paper P with ink can be avoided.
When a length of the remaining area of the openings 80 (area that does not overlap with the paper P) in the paper conveyance direction is equal to or smaller than a predetermined value (for example, several millimeters) due to the paper P overlapping part of the openings 80, the execution of flushing for the remaining area of the openings 80 may cause soiling of the paper P by the ink proceeding to the area other than the remaining area of the openings 80 and landing on and soiling the paper P due to variations of an ink discharge angle of the ink discharged during flushing.
Therefore, it is desirable that the discharge control portion 110a stops the ink discharge toward the openings 80. In other words, when it is determined that the paper P overlaps part of the openings 80 of the opening row 81b and the length of the remaining area of the openings 80 in the paper conveyance direction is equal to or smaller than the predetermined value, the discharge control portion 110a desirably stops the ink discharge by the recording heads 17a to 17c for the openings 80. This avoids the possibility of soiling the paper P due to the variations in the ink discharge angle when executing the flushing for the openings 80 (especially for the remaining area that does not overlap the paper P).
Even when the paper P is separated from the openings 80 of each opening group 82 (opening row 81a, opening row 81b) on the first conveyance belt 8, if the conveyance of the paper P is delayed, for example, for some reason and the separation distance is equal to or smaller than the predetermined distance (for example, several millimeters), if flushing is performed on the above-mentioned openings 80, a risk of causing soiling the paper P with the ink proceeding in the direction other than the direction of the openings 80 and landing on and soiling the nearby paper P due to variations in the discharge angle of the ink discharged during the flushing.
Therefore, it is desirable that the discharge control portion 110a calculates the separation distance between the openings 80 and the paper P in the paper conveyance direction in accordance with the detection results of the openings 80 and the paper P by the opening detection sensor 23, and stops the ink discharge from the recording heads 17a to 17c for the openings 80 when the separation distance is equal to or smaller than the predetermined distance. This avoids the possibility of soiling the paper P that is placed near the openings 80 due to the variations of the ink discharge angle during the flushing for the openings 80.
In the above description, one opening detection sensor 23 is used to detect one opening 80 in the particular opening row 81a. In addition, another opening detection sensor that detects the openings 80 of the other opening row 81b may also be provided. Then, such an opening detection sensor detects the paper P, and the discharge control portion 110a may identify the flushing executable timing for the openings 80 of the other opening row 81b in accordance with the detection results of the openings 80 of the other opening row 81b and the paper P by the opening detection sensor.
As described above, the printer 100 that functions as the inkjet recording device according to the present embodiment includes the opening detection sensor 23 that detects both regularly reflected light and diffusely reflected light. In this case, as described above, the discharge control portion 110a can recognize the first conveyance belt 8, the openings 80, and the paper P separately in accordance with the output signal from the opening detection sensor 23. Therefore, in the factory settings of the printer 100, the flushing timing adjustment method described above can be carried out in accordance with the output results of the opening detection sensor 23. After shipment from the factory, the flushing control described above can be performed by the discharge control portion 110a in accordance with the output results of the opening detection sensor 23. In other words, the opening detection sensor 23 used for the flushing timing adjustment in the factory settings can also be effectively used to control the flushing after shipment from the factory.
In the above, the case where the paper P is suctioned onto and conveyed on the first conveyance belt 8 by the negative-pressure suction has been described. Alternatively, the first conveyance belt 8 may electrically be charged, and the paper P is electrostatically suctioned onto and conveyed on the first conveyance belt 8 (electrostatic suctioning).
In the above, the case where the color printer that records color images using four-color inks has been described as an example of the inkjet recording device has been described. Alternatively, the flushing timing adjustment method and the flushing control are applicable to the case where a monochrome printer that records monochrome images with black ink is used.
The invention is applicable to inkjet printers and other inkjet recording devices.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-075586 | Apr 2020 | JP | national |
| 2021-020462 | Feb 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/015703 | 4/16/2021 | WO |
