Image recording device

Abstract

To surely detect abnormal conveyance of a recording medium.SOLUTION: An image recording device comprises: a sensor group 8 including a plurality of sensors that can sense presence or absence of sheets P at a plurality of sensing positions separated with respect to a conveyance direction on a conveyance passage for the sheets P by a conveying mechanism 2; and a media sensor 7, mounted on a carriage 4 and arranged at a position in parallel to a nozzle along a scanning direction, the media sensor which can obtain color density of the sheet P. A control part 9, when the sensors included in the sensor group 8 sense presence of the sheet P at all sensing positions on the conveyance passage, determines whether the conveyance mechanism 2 conveys the sheet P normally or not, on the basis of the color density of the sheet P obtained by the media sensor 7.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image recording device for recording an image on a recording medium. [Background technology]

[0002] Patent Document 1 discloses a paper transport system that transports paper (recording media) in an image forming system (image recording device) such as an inkjet printer. This paper transport system is equipped with a sensor group including multiple sensors that are spaced apart on the paper transport path. Based on detection signals from the sensor group, it is determined that a paper jam has occurred when a sensor located at a position where paper should be present if paper transport is normal does not detect paper. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-152533 Summary of the Invention [Problem to be solved by the invention]

[0004] In an image recording device equipped with the paper transport system described above, it is possible to record an image on a recording medium whose length along the transport direction is longer than the distance between the sensor located most upstream and the sensor located most downstream in the paper transport direction on the transport path. In such a case, the paper may be detected by all sensors in the sensor group. If an abnormality occurs in this state that prevents the paper from being transported, the abnormality cannot be detected by the detection signals from the sensor group.

[0005] An object of the present invention is to provide an image recording apparatus that can reliably detect abnormalities in the conveyance of a recording medium. [Means for solving the problem]

[0006] The image recording device of the present invention includes a transport mechanism that transports a recording medium in a transport direction, a carriage, a movement mechanism that reciprocates the carriage in a direction intersecting the transport direction, a head mounted on the carriage and having nozzles that can eject ink onto the recording medium transported by the transport mechanism, a plurality of first sensors that can detect the presence or absence of a recording medium at at least two detection positions spaced apart in the transport direction on a path along which the recording medium is transported by the transport mechanism, a second sensor that is mounted on the carriage and aligned with the nozzles along the intersecting direction and can acquire the color density of the recording medium, and a control unit. When the plurality of first sensors detect that the recording medium is present at all of the detection positions, the control unit determines whether the recording medium is being transported normally by the transport mechanism based on the color density of the recording medium acquired by the second sensor. [Effects of the Invention]

[0007] When a recording medium is present at all of the detection positions of the multiple first sensors, it is not possible to determine whether the conveyance mechanism is properly conveying the recording medium based on the output signals from each of the first sensors. If the conveyance mechanism is no longer properly conveying the recording medium, ink is ejected multiple times onto the same position on the recording medium. The more ink is ejected onto the same position on the recording medium, the higher the color density of the recording medium at that position becomes. Therefore, according to the image recording device of the present invention, by obtaining the color density of the recording medium using the second sensor, it is possible to reliably detect abnormalities in the conveyance of the recording medium. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic side view showing the internal structure of a printer according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic plan view of the movement mechanism shown in FIG. [Figure 3] FIG. 2 is a block diagram showing the electrical configuration of the printer shown in FIG. [Figure 4]10 is a graph showing the relationship between the detection value of the media sensor and the position of the paper in the scanning direction when a color density acquisition process is executed. [Figure 5] 10 shows a screen displayed on a display during abnormality notification processing. [Figure 6] 6 is a flowchart illustrating an example of a processing procedure executed in the printer according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] A printer 1 (corresponding to the "image recording device" of the present invention) according to a preferred embodiment of the present invention will be described below with reference to Figures 1 to 3. The up-down direction, front-rear direction, and left-right direction shown in Figure 1 are the up-down direction, front-rear direction, and left-right direction of the printer 1.

[0010] As shown in FIG. 1, the printer 1 mainly comprises a housing 11, a feed tray 12, a feed roller 13, a manual feed tray 15, a feed roller 16, a conveying mechanism 2, a cutter 3, a carriage 4, a head 5, a moving mechanism 6, a media sensor 7, a paper output tray 18, a group of sensors 8, and a control unit 9.

[0011] The feed tray 12 is disposed below the head 5 within the housing 11. The feed tray 12 can be inserted into and removed from the housing 11 in the front-to-rear direction through an opening 17a formed in the front wall of the housing 11. The feed tray 12 can accommodate a roll R. The feed tray 12 has a roll support portion 12a that supports the roll R. The feed tray 12 may also be able to accommodate cut paper in addition to the roll R. The roll R is a long piece of paper P wound in a roll shape around the outer peripheral surface of a cylindrical core Rc.

[0012] The feed roller 13 feeds the paper P unwound from the roll R supported by the roll support portion 12a from the feed tray 12. The feed roller 13 is rotated by the drive of a feed motor 13a (see FIG. 3). When the feed motor 13a is driven under the control of the control portion 9, the feed roller 13 rotates, and a conveying force is applied from the front to the rear to the paper P in contact with the feed roller 13. This causes the paper P to be fed out of the feed tray 12. The rear wall 12b provided at the rear end of the feed tray 12 is inclined so that the upper end is located further rearward than the lower end. Therefore, the paper P fed out of the feed tray 12 is directed diagonally upward.

[0013] The manual tray 15 is provided behind the head 5. The manual tray 15 is a plate-like member rotatably supported by the housing 11. The manual tray 15 can be housed in an opening 17b formed in the rear wall of the housing 11. When the manual tray 15 is housed in the opening 17b, the manual tray 15 forms the rear wall of the housing 11. As shown in FIG. 1, the manual tray 15 can be rotated from the position housed in the opening 17b to a position where paper P can be placed. A-size or B-size cut paper, or long paper whose longitudinal length is longer than that of cut paper, is placed on the manual tray 15.

[0014] The feed roller 16 comes into contact with the paper P placed on the manual tray 15 and feeds the paper P from the manual tray 15. When multiple sheets of paper P are stacked on the manual tray 15, the feed roller 16 feeds the uppermost sheet of paper P from the manual tray 15. The feed roller 16 is rotated by the drive of a feed motor 16a (see FIG. 3). When the feed motor 16a is driven under the control of the control unit 9, the feed roller 16 rotates and a conveying force is applied in a direction from rear to front to the paper P in contact with the feed roller 16. As a result, the paper P is sent out from the manual tray 15.

[0015] The transport mechanism 2 transports the paper P in the transport direction. The transport mechanism 2 includes an intermediate roller pair 21, transport roller pairs 22 and 23, a discharge roller pair 24, and guide members 25 and 26.

[0016] The intermediate roller pair 21 is composed of a drive roller that rotates when driven by an intermediate motor 21a (see FIG. 3) and a driven roller that rotates along with the drive roller. When the intermediate motor 21a is driven under the control of the control unit 9, the intermediate roller pair 21 rotates while sandwiching the paper P, thereby transporting the paper P. The intermediate roller pair 21 is located above the rear end of the feed tray 12. The intermediate roller pair 21 sandwiches and transports the paper P upward as the paper P is fed from the feed tray 12 by the feed roller 13 and heads diagonally upward.

[0017] Guide member 25 is located above intermediate roller pair 21. Guide member 25 guides forward paper P that is transported upward by intermediate roller pair 21. Guide member 26 is located in front of feed roller 16. Guide member 26 guides forward paper P that has been sent out from manual tray 15 by feed roller 16.

[0018] The transport roller pair 22 is located behind the head 5, and the transport roller pair 23 is located in front of the head 5. The transport roller pairs 22 and 23 are each composed of a drive roller that rotates when driven by transport motors 22a and 23a (see FIG. 3), and a driven roller that rotates along with the drive roller. When the transport motors 22a and 23a are driven under the control of the control unit 9, the transport roller pair 22 and 23 rotate while sandwiching the paper P to transport the paper P. The transport roller pair 22 transports the paper P guided forward by guide members 25 and 26 forward. The transport roller pair 23 sandwiches the paper P transported forward by the transport roller pair 22 and transports it forward.

[0019] The discharge roller pair 24 is located in front of the transport roller pair 23 and behind the paper output tray 18. The discharge roller pair 24 is composed of a drive roller that rotates when driven by a discharge motor 24a (see FIG. 3), and a driven roller that rotates along with the drive roller. When the discharge motor 24a is driven under the control of the control unit 9, the discharge roller pair 24 rotates while sandwiching the paper P, and transports the paper P.

[0020] When the paper P is being conveyed forward by the conveying roller pair 22, 23, the discharge roller pair 24 conveys the paper P forward together with the conveying roller pair 22, 23. This allows the paper P to be discharged onto the paper discharge tray 18.

[0021] Furthermore, when a switchback sensor 85 (described later) detects that the rear end of the paper P (the upstream end in the transport direction) is located between the transport roller pair 23 and the discharge roller pair 24, the discharge motor 24a is rotated in the opposite direction to when the paper P is discharged to the paper output tray 18. At this time, the discharge roller pair 24 transports the paper P rearward. This allows the paper P to be sent to the switchback path 32 located below the transport roller pairs 22, 23. In other words, the discharge roller pair 24 functions as a switchback roller.

[0022] Here, the path along which the paper P sent out from the feed tray 12 is conveyed by the conveyance mechanism 2 is referred to as the first conveyance path 31a. In the first conveyance path 31a, the paper P is sent out diagonally upward from the feed tray 12 as shown by the arrow A1 in FIG. 1, then conveyed upward by the intermediate roller pair 21, guided forward by the guide member 25, and conveyed forward by the conveyance roller pairs 22 and 23 and the discharge roller pair 24. In this way, the conveyance mechanism 2 conveys the paper P unwound from the roll R along the first conveyance path 31a in the conveyance direction from the feed tray 12 toward the discharge tray 18.

[0023] The path along which the paper P sent out from the manual tray 15 is conveyed by the conveyance mechanism 2 is referred to as the second conveyance path 31b. In the second conveyance path 31b, the paper P is sent forward from the manual tray 15 as shown by arrow A2 in FIG. 1, then guided forward by a guide member 26 and conveyed forward by pairs of conveyance rollers 22 and 23 and a pair of discharge rollers 24. The conveyance mechanism 2 conveys the paper P placed on the manual tray 15 along the second conveyance path 31b in the conveyance direction from the manual tray 15 toward the discharge tray 18. Note that the downstream side of the guide member 25 in the first conveyance path 31a in the conveyance direction is the same as the downstream side of the guide member 26 in the conveyance direction in the second conveyance path 31b.

[0024] As described above, the paper sheet P conveyed rearward by the discharge roller pair 24 is conveyed diagonally downward while heading rearward in the switchback path 32 as shown by the arrow B in Fig. 1. The paper sheet P sent to the switchback path 32 is sent to a midpoint of the first conveying path 31a and is sent to the conveying roller pair 22 from the upstream side in the conveying direction.

[0025] The cutter 3 is located between the rear end of the feed tray 12 and the pair of intermediate rollers 21. The cutter 3 is composed of, for example, a disk-shaped rotary blade and a driven blade. The rotary blade of the cutter 3 is rotated by the driving of a cutting motor 3a (see FIG. 3), and the cutter 3 moves back and forth in the left-right direction. The paper P unwound from the roll R and transported is cut in the width direction of the paper P by the cutter 3 when the cutting motor 3a is driven under the control of the control unit 9.

[0026] The head 5 includes a plurality of nozzles 51 (see FIG. 2) formed on its underside, and a driver IC 52 (see FIG. 3). As shown in FIG. 2, the plurality of nozzles 51 form a nozzle row 51a along the transport direction (the direction from top to bottom in the figure). The head 5 has a plurality of nozzle rows 51a arranged in a direction (scanning direction) perpendicular to the transport direction. When the driver IC 52 is driven under the control of the control unit 9, ink is ejected from the nozzles 51, and an image is recorded on the paper P when the paper P transported by the transport mechanism 2 passes an image recording position facing the underside of the head 5. The head 5 is mounted on a carriage 4.

[0027] The movement mechanism 6 has two guide rails 61, 62 and a carriage motor 63 (see FIG. 3). As shown in FIG. 2, the two guide rails 61, 62 are arranged spaced apart from each other in the front-rear direction and extend in the left-right direction. The carriage 4 is arranged to straddle the two guide rails 61, 62. The carriage 4 is connected to the carriage motor 63 via a belt (not shown) or the like. When the carriage motor 63 is driven under the control of the control unit 9, the carriage 4 moves in the left-right direction (scanning direction) along the guide rails 61, 62.

[0028] The media sensor 7 is mounted on the carriage 4. As shown in FIG. 2, the media sensor 7 is positioned to align with the nozzles 51 in the scanning direction. In this embodiment, the media sensor 7 is positioned to align with the nozzles 51 located most upstream in the transport direction in the scanning direction. The media sensor 7 is positioned on one side (left side) of the multiple nozzle rows 51a in the scanning direction.

[0029] The media sensor 7 is composed of a known optical sensor. The media sensor 7 has a light-emitting unit and a light-receiving unit. The media sensor 7 is configured so that the light-emitting unit emits light and the light-receiving unit receives the light reflected from the paper P located at the image recording position opposite the underside of the head 5. The higher the color density of the paper P, the less light is reflected from the paper P. Therefore, the media sensor 7 can obtain the color density of the paper P based on the amount of light reflected from the paper P. In other words, the media sensor 7 corresponds to the "second sensor" of the present invention.

[0030] The paper output tray 18 is disposed in front of the head 5 within the housing 11 and above the feed tray 12. The paper output tray 18 can be inserted into and removed from the housing 11 in the front-to-rear direction through an opening 17c formed in the front wall of the housing 11. The paper P on which an image has been recorded by the head 5 is received in the paper output tray 18.

[0031] The sensor group 8 consists of five sensors: a roll detection sensor 81, a paper presence / absence detection sensor 82, an intermediate registration sensor 83, a registration sensor 84, and a switchback sensor 85. Each sensor included in the sensor group 8 can detect the presence or absence of paper P at detection positions D1 to D5 on the transport path of paper P. The detection positions D1 to D5 of the sensors included in the sensor group 8 are spaced apart from each other in the transport direction. In other words, each sensor included in the sensor group 8 corresponds to a "first sensor" of the present invention.

[0032] The detection positions D1 to D5 of all sensors included in the sensor group 8 are located on the first transport path 31a. Of the five sensors included in the sensor group 8, the detection positions D4 and D5 of the registration sensor 84 and the switchback sensor 85 are located in a portion of the first transport path 31a that is common to the second transport path 31b.

[0033] Of the sensors included in the sensor group 8, the detection positions D1 to D4 of the roll detection sensor 81, paper presence / absence detection sensor 82, intermediate registration sensor 83, and registration sensor 84 are all located upstream in the transport direction from the path of reciprocating movement of the carriage 4 by the movement mechanism 6. In addition, the detection position D5 of the switchback sensor 85 is located downstream in the transport direction from the path of reciprocating movement of the carriage 4 by the movement mechanism 6.

[0034] A known method can be used as a method for detecting the presence or absence of paper P by each sensor included in the sensor group 8. For example, a light emitting unit emits light toward the detection position, and a light receiving unit receives the light reflected from paper P located at the detection position, thereby detecting the presence of paper P at the detection position. Alternatively, an actuator that displaces when it comes into contact with paper P may be provided at the detection position, and the presence of paper P at the detection position may be detected by detecting the displacement of the actuator.

[0035] The roll detection sensor 81 detects the presence or absence of paper P at a detection position D1 near the rear end of the roll support section 12a. By detecting paper P unwound from the roll R by the roll detection sensor 81, it is possible to detect that the roll R is supported by the roll support section 12a.

[0036] The paper presence / absence detection sensor 82 detects the presence or absence of paper P at a detection position D2 near the feed roller 13. By detecting the paper P with the paper presence / absence detection sensor 82, it is possible to detect that the paper P is placed in a position where it can be fed by the feed roller 13.

[0037] The intermediate registration sensor 83 detects the presence or absence of the paper P at a detection position D3 near the intermediate roller pair 21, upstream of the intermediate roller pair 21 in the conveying direction, and downstream of the cutter 3 in the conveying direction.

[0038] The registration sensor 84 detects the presence or absence of the paper P at a detection position D4 that is near the pair of conveying rollers 22 and upstream in the conveying direction from the pair of conveying rollers 22. By detecting the paper P with the registration sensor 84, it can be detected that the paper P has been conveyed to the vicinity of the pair of conveying rollers 22.

[0039] The switchback sensor (SB sensor) 85 detects the presence or absence of the paper P at a detection position D5 between the pair of conveying rollers 23 and the pair of discharge rollers 24. By detecting the paper P with the switchback sensor 85, it can be detected that the rear end of the paper P is located between the pair of conveying rollers 23 and the pair of discharge rollers 24.

[0040] The control unit 9 controls the entire printer 1. As shown in Fig. 3, the control unit 9 is electrically connected to the feed motors 13a and 16a, the intermediate motor 21a, the transport motors 22a and 23a, the discharge motor 24a, the cutting motor 3a, the driver IC 52, the carriage motor 63, the media sensor 7, the sensors included in the sensor group 8, the display 96, etc.

[0041] The display 96 is provided on the outer surface of the housing 11. The display 96 displays various information related to the printer 1 to notify the user, and corresponds to the "notification means" of the present invention. The notification means may be a speaker.

[0042] 3, the control unit 9 includes a CPU (Central Processing Unit) 91, a ROM (Read Only Memory) 92, a RAM (Random Access Memory) 93, and an ASIC (Application Specific Integrated Circuit) 94. The ROM 92 stores programs executed by the CPU 91 and the ASIC 94, various fixed data, etc. The RAM 93 temporarily stores data (image data, etc.) required when executing a program.

[0043] The control unit 9 determines whether the transport of the paper P by the transport mechanism 2 is being performed normally based on the output signals from each sensor included in the sensor group 8. That is, the control unit 9 predicts the position of the paper P transported by the transport mechanism 2 based on the driving status of the feed motors 13a, 16a, the intermediate motor 21a, the transport motors 22a, 23a, and the discharge motor 24a. Then, the control unit 9 determines that the transport of the paper P by the transport mechanism 2 is not being performed normally when the paper P is not detected at a detection position that is the predicted position of the paper P among the detection positions D1 to D5 of each sensor included in the sensor group 8, or when the paper P is detected at a detection position where the paper P is not expected to be present.

[0044] After the registration sensor 84 detects that the paper P being transported in the transport direction has reached a detection position D4 near the pair of transport rollers 22, the control unit 9 controls the transport motor 22a that drives the pair of transport rollers 22 to perform a cueing operation to transport the paper P to the print start position L0 (see FIG. 1). The paper P positioned at the print start position L0 faces at least the nozzle 51 positioned most upstream in the transport direction.

[0045] After aligning the paper P, the control unit 9 performs a transport process in which the transport roller pair 22, 23 transports the paper P a predetermined distance at a time in the transport direction, and a scanning process in which ink is ejected from the multiple nozzles 51 of the head 5 while moving the carriage 4 in the scanning direction, thereby recording an image on the paper P. In other words, the printer 1 is a serial type. In this embodiment, in the scanning process, ink is ejected from the nozzles 51 when the carriage 4 is moved from one side in the scanning direction (left side in FIG. 2) to the other side (right side in FIG. 2).

[0046] When the sensors included in the sensor group 8 detect that paper P is present at all detection positions located on the transport path along which the paper P on which an image is recorded is transported, the control unit 9 determines whether the transport mechanism 2 is transporting the paper P normally based on the color density of the paper P acquired by the media sensor 7.

[0047] 1, when the leading edge of the sheet P fed from the feed tray 12 reaches the detection position D5 of the switchback sensor 85, the sheet P is positioned at all of the detection positions D1 to D5 on the first transport path 31a. In this state, the sensors in the sensor group 8 always only detect the presence of the sheet P, regardless of whether the sheet P is being transported normally by the transport mechanism 2 or if a jam or other problem occurs that prevents the sheet P from being transported normally by the transport mechanism 2. Therefore, it is not possible to determine whether the sheet P is being transported normally by the transport mechanism 2 based on the output signals from the sensors in the sensor group 8. Therefore, the control unit 9 determines whether the sheet P is being transported normally by the transport mechanism 2 based on the color density of the sheet P acquired by the media sensor 7.

[0048] When an image is recorded on paper P unwound from a roll R stored in the feed tray 12, the paper P is transported along the first transport path 31a. Therefore, when the control unit 9 detects that paper P is present at all of the detection positions D1 to D5 located on the first transport path 31a, the control unit 9 determines whether the transport mechanism 2 is transporting the paper P normally, based on the color density of the paper P acquired by the media sensor 7.

[0049] Furthermore, when an image is recorded on paper P placed on the manual feed tray 15, the paper P is transported along the second transport path 31b. Therefore, when the control unit 9 detects that paper P is present at all of the detection positions D4 and D5 located on the second transport path 31b, it determines whether the transport mechanism 2 is transporting the paper P normally, based on the color density of the paper P acquired by the media sensor 7.

[0050] The control unit 9 executes a color density acquisition process to acquire the color density of the paper P at each position in the scanning direction using the media sensor 7 while moving the carriage 4 in the scanning direction using the movement mechanism 6. In this embodiment, the color density acquisition process is executed when the carriage 4 is moved from one side in the scanning direction (the left side in FIG. 2) to the other side (the right side in FIG. 2), similar to the timing at which ink is ejected from the nozzles 51 in the scanning process.

[0051] The color density acquisition process includes a first color density acquisition process that acquires the color density (first color density) of the paper P before ink is ejected from the nozzles 51, and a second color density acquisition process that is performed for each pass of image recording and acquires the color density (second color density) of the paper P onto which ink has been ejected from the nozzles 51. The first color density acquisition process is executed after the paper P has been indexed and before image recording begins. The first color density, which is the color density of the paper P acquired in the first color density acquisition process, is stored in RAM 93.

[0052] Here, the relationship between the detection value of the media sensor 7 when the color density acquisition process is executed and the position in the scanning direction of the paper P will be explained with reference to the graph shown in Figure 4. The graph shown by the solid line in Figure 4 is the detection value of the media sensor 7 obtained by executing the first color density acquisition process when the paper P is plain white. Because the color density of the paper P before ink is ejected is constant regardless of location, the detection value of the media sensor 7 obtained in the first color density acquisition process (the amount of light reflected from the paper P) is approximately constant in the scanning direction of the paper P.

[0053] When the paper P is colored, the detection value (amount of light reflected from the paper P) of the media sensor 7 obtained in the first color density acquisition process is smaller than when the paper P is white, and is constant in the scanning direction of the paper P. When the paper P has a pattern, for example, the detection value (amount of light reflected from the paper P) of the media sensor 7 obtained in the first color density acquisition process may fluctuate in the scanning direction of the paper P.

[0054] The dashed line in Figure 4 shows the detection values ​​of the media sensor 7 obtained by moving the carriage 4 from one side of the scanning direction (left in Figure 2) to the other side (right in Figure 2) to record an image for one pass on plain white paper P, while simultaneously executing the second color density acquisition process (first time). After one pass of image recording has been performed, the color density of the portions of the paper P onto which ink has been ejected becomes higher than before image recording. Therefore, the detection values ​​of the media sensor 7 obtained in the second color density acquisition process (amount of light reflected from paper P) are partially smaller than the detection values ​​of the media sensor 7 obtained in the first color density acquisition process.

[0055] In addition, in the area of ​​the paper P where one pass of image recording is performed, the detection value of the media sensor 7 obtained in the second color density acquisition process is almost the same as the detection value of the media sensor 7 obtained in the first color density acquisition process in the area where no ink is ejected. More specifically, due to detection errors, there are some areas where the detection value of the media sensor 7 obtained in the second color density acquisition process is larger than the detection value of the media sensor 7 obtained in the first color density acquisition process.

[0056] The graph shown by the dashed dotted line in Figure 4 is the detection value of the media sensor 7 obtained by performing a second color density acquisition process (for the second time) at the same time as performing another one-pass image recording on a location on the paper P where one pass of image recording has already been performed. By performing two passes of image recording on the same location on the paper P, the color density of the paper P becomes higher than when one pass of image recording is performed. Therefore, the detection value of the media sensor 7 obtained in the second second color density acquisition process (amount of light reflected from the paper P) is smaller than the detection value of the media sensor 7 obtained in the first second color density acquisition process.

[0057] In other words, if the transport mechanism 2 is not transporting the paper P normally and multiple passes of image recording are performed at the same position on the paper P, the detection value of the media sensor 7 (amount of reflected light from the paper P) obtained in the second color density acquisition process gradually becomes smaller.

[0058] For each pass of image recording, the control unit 9 executes a comparison process that compares a density difference, which is the difference between the first color density of the paper P acquired in the first color density acquisition process and the second color density of the paper P acquired in the second color density acquisition process, with a predetermined threshold. That is, in the comparison process, the increase in color density from the paper P before ink is ejected from the nozzles 51 is compared with the threshold. When ink is ejected multiple times at the same position on the paper P, the paper P, which contains a large amount of ink, bends. When the paper P bends, the bottom surface of the head 5 is rubbed by the paper P. Therefore, for example, the threshold is set to the increase in color density of the paper P when ink is ejected onto the paper P to the extent that the paper P bends enough to rub against the bottom surface of the head 5.

[0059] Furthermore, the control unit 9 executes a judgment process to determine whether the transport mechanism 2 is transporting the paper P normally, based on the difference in color density of the paper P acquired in the first color density acquisition process and the second color density acquisition process. That is, in the judgment process, if the density difference exceeds a threshold value in the comparison process, it is determined that the transport mechanism 2 is not transporting the paper P normally.

[0060] Furthermore, if the control unit 9 determines that the transport of the paper P by the transport mechanism 2 is not being performed normally, it executes an abnormality notification process to display an abnormality notification screen 97 containing a message to that effect on the display 96, as shown in Figure 5.

[0061] Next, the operation of the printer 1 when recording an image on paper P will be described with reference to the flowchart shown in Fig. 6. The flowchart in Fig. 6 shows the operation when recording an image for one page.

[0062] First, the control unit 9 starts feeding the paper P (S1). When an image is to be recorded on the paper P unwound from the roll R, the control unit 9 controls the feed motor 13a to feed the paper P from the feed tray 12. When an image is to be recorded on the paper P placed on the manual feed tray 15, the control unit 9 controls the feed motor 16a to feed the paper P from the manual feed tray 15.

[0063] Thereafter, the control unit 9 determines whether the transport of the paper P by the transport mechanism 2 is being performed normally based on the output signals from each sensor included in the sensor group 8 (S2). If it determines that the transport is not being performed normally (S2: NO), the process proceeds to S15, which will be described later. On the other hand, if it determines that the transport is being performed normally (S2: YES), the control unit 9 determines whether the paper P has been detected by the register sensor 84 (S3). If it determines that the paper P has not been detected by the register sensor 84 (S3: NO), the process returns to S2.

[0064] Then, when it is determined that the paper P has been detected by the registration sensor 84 (S3: YES), the control unit 9 performs a cueing operation to transport the paper P to the print start position L0 (S4). Next, the control unit 9 executes a first color density acquisition process to acquire the color density (first color density) of the paper P before ink is ejected from the nozzles 51 using the media sensor 7 (S5). Then, the control unit 9 stores the first color density acquired in the first color density acquisition process in the RAM 93 (S6).

[0065] Next, the control unit 9 determines whether the sensors included in the sensor group 8 have detected the presence of paper P at all detection positions located on the transport path along which paper P on which an image is to be recorded is transported (S7). If there are detection positions at which the presence of paper P is not detected (S7: NO), the control unit 9 executes image recording for one pass (S8). That is, while moving the carriage 4 in the scanning direction, the control unit 9 executes a scanning process in which ink is ejected from the multiple nozzles 51 of the head 5, and a transport process in which paper P is transported a predetermined distance in the transport direction.

[0066] Thereafter, the control unit 9 determines whether image recording for all passes to be recorded on one page has been completed (S9). If it determines that image recording for all passes has been completed (S9: YES), the process ends. If it determines that image recording for all passes has not yet been completed (S9: NO), the control unit 9 determines whether the transport of the paper P by the transport mechanism 2 is proceeding normally based on the output signals from each sensor included in the sensor group 8 (S10). If it determines that transport is not proceeding normally (S10: NO), the process proceeds to S15, which will be described later. On the other hand, if it determines that transport is proceeding normally (S10: YES), the process returns to S7.

[0067] Furthermore, in S7, if it is determined that the paper P is present at all detection positions (S7: YES), the control unit 9 performs image recording for one pass and simultaneously executes second color density acquisition processing to acquire the color density (second color density) of the paper P onto which ink is ejected from the nozzles 51 (S11). Thereafter, the control unit 9 determines whether image recording for all passes to be recorded on one page has been completed (S12). If it is determined that image recording for all passes has been completed (S12: YES), the processing ends.

[0068] On the other hand, if it is determined that image recording for all passes has not yet been completed (S12: NO), the control unit 9 executes a comparison process (S13) in which the density difference, which is the difference between the first color density acquired in S5 and the second color density acquired in S11, is compared with a predetermined threshold. Note that if the process of S11 has been executed multiple times, the comparison process of S13 uses the second color density acquired in the most recent S11. Then, the control unit 9 determines whether the density difference exceeds the threshold (S14).

[0069] If it is determined that the density difference exceeds the threshold value (S14: YES), the control unit 9 executes an abnormality notification process (S15) to display an abnormality notification screen 97 (see FIG. 5) including a message that the transport mechanism 2 is not transporting the paper P normally on the display 96. On the other hand, if it is determined that the density difference does not exceed the threshold value (S14: NO), the process returns to S7.

[0070] (Effects of the embodiment) As described above, the printer 1 of the first embodiment includes the transport mechanism 2 that transports the paper P in the transport direction, the carriage 4, the movement mechanism 6 that moves the carriage 4 back and forth in the scanning direction, the head 5 that is mounted on the carriage 4 and has the nozzles 51 that can eject ink onto the paper P transported by the transport mechanism 2, the sensor group 8 that includes multiple sensors that can detect the presence or absence of the paper P at multiple detection positions D1 to D5 that are spaced apart in the transport direction on the transport path of the paper P by the transport mechanism 2, the media sensor 7 that is mounted on the carriage 4 and positioned alongside the nozzles 51 in the scanning direction and can acquire the color density of the paper P, and the control unit 9. When the sensors included in the sensor group 8 detect that the paper P is present at all detection positions on the transport path, the control unit 9 determines whether the transport mechanism 2 is transporting the paper P normally based on the color density of the paper P acquired by the media sensor 7.

[0071] With the above-described configuration, when paper P is present at all detection positions on the transport path, it is not possible to determine whether the transport mechanism 2 is transporting the paper P normally based on the output signals from each sensor included in the sensor group 8. If the transport mechanism 2 is no longer transporting the paper P normally, ink is ejected multiple times onto the same position on the paper P. The more ink is ejected onto the same position on the paper P, the higher the color density of the paper P at that position. Therefore, by obtaining the color density of the paper P using the media sensor 7, it is possible to reliably detect transport abnormalities in the paper P.

[0072] Furthermore, in the printer 1 of the above-described embodiment, the control unit 9 executes a color density acquisition process in which the media sensor 7 acquires the color density of the paper P at each position in the scanning direction while moving the carriage 4 in the scanning direction using the movement mechanism 6, and a determination process in which the transport mechanism 2 determines whether the paper P is being transported normally based on the difference in the color densities of the paper P acquired in each of the two color density acquisition processes. If the paper P is colored, it may be difficult to detect a transport abnormality in the paper P based on the color density of the paper P acquired in a single color density acquisition process. With the above-described configuration, it is determined whether the paper P is being transported normally based on the difference in the color densities of the paper P acquired in each of the two color density acquisition processes, so that transport abnormalities in the paper P can be detected more reliably.

[0073] Furthermore, in the printer 1 of the above-described embodiment, the color density acquisition process includes a first color density acquisition process that acquires the color density of the paper P before ink is ejected from the nozzles 51, and a second color density acquisition process that is performed for each pass of image recording and acquires the color density of the paper P after ink is ejected from the nozzles 51. The control unit 9 then performs a comparison process for each pass of image recording in which a density difference, which is the difference between the first color density, which is the color density of the paper P acquired in the first color density acquisition process, and the second color density, which is the color density of the paper P acquired in the second color density acquisition process, is compared with a predetermined threshold. In the determination process, if the density difference in the comparison process exceeds the threshold, it is determined that the paper P is not being transported normally by the transport mechanism 2. If the paper P is not being transported normally and multiple passes of image recording are performed at the same position, the color density acquired in the second color density acquisition process gradually becomes darker. Therefore, if the density difference, which is the difference between the first color density, which is the color density of the paper P before ink is ejected, and the second color density, which is the color density of the paper P after ink has been ejected, exceeds a predetermined threshold value, it is determined that the paper P is not being transported normally, thereby making it possible to more reliably detect abnormalities in the transport of the paper P.

[0074] Additionally, the printer 1 of the above-described embodiment further includes a display 96 for notifying the user of information. When the control unit 9 determines that the transport mechanism 2 is not transporting the paper P normally, it displays an abnormality notification screen 97 containing a message to that effect on the display 96, and further executes an abnormality notification process for notifying the user of the transport abnormality in the transport mechanism 2. Therefore, the user can be notified that a transport abnormality has occurred and be prompted to take action.

[0075] Furthermore, in the printer 1 of the above-described embodiment, the transport mechanism 2 transports paper P unwound from a roll R, which is a long piece of paper P wound around a core Rc. In some cases, an end of the long piece of paper P is fixed to the core Rc of the roll R. In such a case, when all of the paper P is unwound from the roll R, the transport mechanism 2 is no longer able to transport the paper P. In this embodiment, even in such a case, it is possible to detect that the paper P is not being transported based on the color density of the paper P acquired by the media sensor 7.

[0076] Furthermore, in the printer 1 of the above-described embodiment, the multiple sensors included in the sensor group 8 can detect the presence or absence of paper P at detection positions D1 to D4 located upstream of the path of reciprocating movement of the carriage 4 by the movement mechanism 6 in the transport direction, and at detection position D5 located downstream. When the multiple sensors included in the sensor group 8 detect the presence of paper P at detection positions located upstream and downstream of the path of reciprocating movement of the carriage 4, the paper P is located at an image recording position facing the underside of the head 5. Therefore, it is suitable for a printer 1 configured in this way to employ the present invention, which determines whether paper P is being transported normally by the transport mechanism 2 based on the color density of the paper P acquired by the media sensor 7.

[0077] Although the embodiments of the present invention have been described above with reference to the drawings, the specific configurations should not be considered to be limited to these embodiments. The scope of the present invention is defined by the claims rather than the above description of the embodiments, and further includes all modifications within the meaning and scope of the claims.

[0078] In the above-described embodiment, the detection positions D1 to D5 of all sensors included in the sensor group 8 are located on the first transport path 31a, and the detection positions D4 and D5 of the registration sensor 84 and the switchback sensor 85 are located on the second transport path 31b. However, this is not limiting. It is sufficient that at least two detection positions spaced apart in the transport direction are located on the first transport path 31a and the second transport path 31b. These two detection positions are preferably located upstream and downstream of the path of reciprocating movement of the carriage 4 by the movement mechanism 6 in the transport direction, respectively. However, they may be located only on either the upstream or downstream side of the path of reciprocating movement of the carriage.

[0079] Furthermore, in the above embodiment, the media sensor 7 is positioned in a position aligned in the scanning direction with the nozzle 51 located most upstream in the transport direction, but this is not limited to this. The media sensor 7 may be positioned between the nozzle 51 located most downstream in the transport direction and the nozzle 51 located most upstream in the transport direction.

[0080] Furthermore, in the above-described embodiment, the media sensor 7 is disposed on one side (left side) of the plurality of nozzle rows 51a in the scanning direction. When recording an image for one pass, ink is ejected from the nozzles 51 while the carriage 4 is moved from one side (left side in FIG. 2) to the other side (right side in FIG. 2) in the scanning direction. The color density acquisition process is executed when the carriage 4 is moved from one side (left side in FIG. 2) to the other side (right side in FIG. 2) in the scanning direction, similar to the ink ejection timing when recording an image for one pass. However, this is not limited to this. For example, when recording an image for one pass, ink may be ejected from the nozzles 51 while the carriage 4 is moved from the other side (right side in FIG. 2) to one side (left side in FIG. 2) in the scanning direction, and the color density acquisition process may be executed when the carriage 4 is moved from one side (left side in FIG. 2) to the other side (right side in FIG. 2) in the scanning direction.

[0081] In the above embodiment, the scanning direction is perpendicular to the transport direction, but the present invention is not limited to this. In other words, the scanning direction may be any direction that intersects with the transport direction.

[0082] Additionally, in the embodiment, a case has been described in which it is determined whether the transport of the paper P by the transport mechanism 2 is proceeding normally based on the difference between the color densities of the paper P acquired in two color density acquisition processes, but this is not limiting. In other words, it may be determined whether the transport of the paper P is proceeding normally based on whether the color density of the paper P acquired in one color density acquisition process exceeds a predetermined threshold value.

[0083] In the above-described embodiment, the case where whether the transport mechanism 2 is transporting the paper P normally is described based on the color density of the paper P before ink is ejected from the nozzles 51 (first color density) acquired in the first color density acquisition process and the color density of the paper P after ink is ejected from the nozzles 51 (second color density) acquired in the second color density acquisition process is described. However, this is not limited to this. For example, whether the transport of the paper P is normal may be determined by comparing the second color densities acquired in the second color density acquisition process, which is performed for each pass of image recording. In other words, if the transport mechanism 2 is not transporting the recording medium normally, multiple passes of image recording are performed at the same position on the paper P. Therefore, the second color density acquired in the second color density acquisition process gradually increases with each pass of image recording. Therefore, if the second color density acquired in the second color density acquisition process gradually increases after multiple passes of image recording, it can be determined that the transport of the paper P is not normal.

[0084] Furthermore, in the above embodiment, when it is determined that the transport of the paper P by the transport mechanism 2 is not being performed normally, an abnormality notification screen 97 including a message to that effect is displayed on the display 96. However, this is not limited to this. For example, a message to the effect that the transport of the paper P by the transport mechanism 2 is not being performed normally may be played through a speaker. Also, a lamp may be provided that lights up when the transport of the paper P by the transport mechanism 2 is not being performed normally.

[0085] The present invention can be applied to any image recording apparatus that performs serial image recording. The recording medium is not limited to paper, but may be cloth or the like. [Explanation of symbols]

[0086] 2. Transport mechanism 4 carriages 5 heads 6 Moving mechanism 7 Media sensor (second sensor) 8 Sensors 9 Control Unit 31a First transport route 31b Second transport route 51 nozzles 81 Roll detection sensor (first sensor) 82 Paper presence detection sensor (first sensor) 83 Intermediate registration sensor (first sensor) 84 Register sensor (first sensor) 85 Switchback sensor (first sensor) 96 Display (notification means) P Paper (recording medium) R roll body Rc winding core

Claims

1. a conveying mechanism that conveys the recording medium in a conveying direction; A carriage; a moving mechanism that moves the carriage back and forth in a direction intersecting the conveying direction; a head mounted on the carriage and having nozzles capable of ejecting ink onto the recording medium transported by the transport mechanism; a plurality of first sensors capable of detecting the presence or absence of a recording medium at at least two detection positions spaced apart in a conveying direction on a conveying path of the recording medium by the conveying mechanism; a second sensor mounted on the carriage and arranged in a position aligned with the nozzles along the intersecting direction, the second sensor being capable of acquiring color density of the recording medium; a control unit; and The control unit determines whether the conveying mechanism is conveying the recording medium normally based on the color density of the recording medium obtained by the second sensor when the plurality of first sensors detect that the recording medium is present at all of the detection positions.

2. The control unit a color density acquisition process for acquiring a color density of the recording medium at each position in the intersecting direction by the second sensor while moving the carriage in the intersecting direction by the movement mechanism; The image recording device according to claim 1, further comprising: a judgment process for determining whether the conveying mechanism is conveying the recording medium normally based on the difference in color density of the recording medium acquired in each of the two color density acquisition processes.

3. The color density acquisition process includes: a first color density acquisition process for acquiring a color density of the recording medium before ink is ejected from the nozzles; a second color density acquisition process for acquiring the color density of the recording medium onto which the ink is ejected from the nozzles, the second color density acquisition process being performed for each pass of image recording, The control unit a comparison process is further performed for each pass of image recording, in which a density difference, which is a difference between the color density of the recording medium acquired in the first color density acquisition process and the color density of the recording medium acquired in the second color density acquisition process, is compared with a predetermined threshold value; 3. The image recording apparatus according to claim 2, wherein, in the judgment process, if the density difference in the comparison process exceeds the threshold value, it is judged that the conveying mechanism is not conveying the recording medium normally.

4. The device further includes a notification means for notifying a user of information, The image recording device described in any one of claims 1 to 3, characterized in that the control unit further executes an abnormality notification process in which the notification means notifies the user of a transport abnormality in the transport mechanism when it determines that the transport mechanism is not transporting the recording medium normally.

5. 5. The image recording device according to claim 1, wherein the transport mechanism transports a long sheet of medium unwound from a roll body in which the long sheet of medium is wound around a core.

6. An image recording device as described in any one of claims 1 to 5, characterized in that the multiple first sensors are capable of detecting the presence or absence of a recording medium at two detection positions located upstream and downstream, respectively, of the path of reciprocating movement of the carriage by the moving mechanism at least in the transport direction.

Images