JP4678010B2 - Belt conveying device and liquid ejection device provided with the same - Google Patents

Description

  The present invention relates to a belt conveyance device that conveys a recording medium by an endless conveyance belt, and a liquid ejection device including the belt conveyance device.

  Patent Document 1 discloses an ink jet recording apparatus that is a liquid ejection apparatus that includes a cleaning roller for cleaning a conveyance belt on which a recording sheet that is a conveyance medium is conveyed, and a line sensor that reads the surface of the conveyance belt. Yes. This inkjet recording apparatus periodically reads the surface of the conveyor belt with a line sensor, detects the contamination level of the conveyor belt from the read data, and there is a difference between the detected contamination level and the contamination level after completion of the previous cleaning. In some cases, cleaning is performed by a cleaning roller.

Japanese Patent Laid-Open No. 11-192692 (FIG. 1)

  However, when the contamination of the conveyance belt is directly detected and it is determined whether or not cleaning is performed based on the detected contamination level, cleaning is performed even for light ink contamination that does not adhere to the conveyance medium. The conveyance efficiency decreases.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a belt conveyance device with improved conveyance efficiency and a liquid ejection device including the belt conveyance device.

The belt conveyance device according to the present invention includes two rollers having rotation axes parallel to each other and the two rollers, and the conveyance medium is in contact with the lower surface of the conveyance medium as the two rollers rotate. a conveyor belt having an outer peripheral surface for conveying the, on the basis of the bottom surface image obtained by the first imaging means and said first imaging means for imaging the lower surface of the transport medium after being conveyed by the conveyor belt, Determination means for determining whether or not the lower surface of the transport medium exceeds a permissible upper limit level . Then, based on the determination means comparing the lower surface image with a reference image having the same size for each corresponding minute region, the lower surface of the transport medium is soiled beyond the allowable upper limit level. Determine whether or not.

According to the belt conveyance device of the present invention, it is possible to quickly detect the contamination of the conveyance belt by imaging the lower surface of the conveyance medium. Since the contamination of the conveying belt is not directly detected, the contamination of the conveying belt that does not contaminate the conveying medium is not detected, and only the contamination of the conveying belt that contaminates the conveying medium is detected. Therefore, unnecessary cleaning of the transport belt and / or stop of the transport belt can be minimized, and transport efficiency is improved. Further, by automating the determination regarding the contamination of the transport belt, it is possible to reduce the time and effort of the user. In addition, it is possible to identify a dirty area on the conveyor belt.

  In addition, the image forming apparatus further includes a second imaging unit that images the lower surface of the conveyance medium before being conveyed by the conveyance belt, and the determination unit uses the image obtained by the second imaging unit as the reference. It is preferable to use it as an image. According to this, by using the lower surface image immediately before the conveyance by the conveyance belt as the reference image, for example, in the case of conveying a conveyance medium having an original pattern, the determination accuracy is improved.

  In addition, when the determination unit determines that the lower surface of the transport medium is dirty beyond the allowable upper limit level, it is preferable to further include a notification unit that notifies the user to that effect. Accordingly, the user can deal with the detected contamination of the conveyor belt with respect to his / her intention.

  In addition, it is preferable that the apparatus further includes a roller stopping unit that stops the rotation of the two rollers when the determination unit determines that the lower surface of the transport medium is dirty beyond the allowable upper limit level. According to this, it is possible to prevent the conveyance medium newly conveyed on the conveyance belt from becoming dirty beyond the allowable upper limit level.

  Furthermore, on the upstream side in the transport direction in which the transport medium is transported, a transport medium supply device that supplies the transport medium to the transport belt, and the lower surface of the transport medium is soiled beyond the allowable upper limit level. It is preferable that the apparatus further includes a conveyance stop unit that stops the conveyance medium supply device when the determination unit determines. According to this, it is possible to reliably prevent the newly transported transport medium from being contaminated exceeding the allowable upper limit level.

  In addition, it is preferable to further include a cleaning means for cleaning the outer peripheral surface of the transport belt. As a result, the dirty conveying belt can be cleaned.

  The cleaning unit may automatically clean the outer peripheral surface of the transport belt when the determination unit determines that the lower surface of the transport medium is dirty beyond the allowable upper limit level. According to this, it is possible to reduce the labor of the user by automatically starting the cleaning.

In another aspect, the belt conveyance device of the present invention is wound around two rollers having mutually parallel rotation shafts and the two rollers, and the conveyance medium is rotated along with the rotation of the two rollers. Obtained by a transport belt having an outer peripheral surface for transporting a transport medium while being in contact with the lower surface, a first imaging unit for capturing an image of the lower surface of the transport medium after being transported by the transport belt, and the first image capturing unit. And determining means for determining whether the lower surface of the transport medium is dirty beyond an allowable upper limit level based on the lower surface image, and a cleaning means for cleaning the outer peripheral surface of the transport belt. The cleaning unit automatically cleans the outer peripheral surface of the transport belt when the determination unit determines that the lower surface of the transport medium is dirty beyond the allowable upper limit level, and the determination unit Is for determining the level of contamination when the lower surface of the transport medium is soiled exceeding an allowable upper limit level, and the time for cleaning the outer peripheral surface of the transport belt by the cleaning device is determined by the determining device. It is preferable to further include a cleaning control means for controlling based on the dirt level determined by the above. Accordingly, it is possible to quickly detect the contamination of the conveyor belt by imaging the lower surface of the conveyor medium. Since the contamination of the conveyance belt is not directly detected, the contamination of the conveyance belt that does not contaminate the conveyance medium is not detected, but only the contamination of the conveyance belt that stains the conveyance medium is detected. Therefore, unnecessary cleaning of the transport belt and / or stop of the transport belt can be minimized, and transport efficiency is improved. Further, by automating the determination regarding the contamination of the transport belt, it is possible to reduce the time and effort of the user. In addition, the dirty conveyor belt can be cleaned. In addition, by automatically starting the cleaning, it is possible to reduce the user's trouble. Also, the cleaning execution time can be made appropriate.

  The liquid ejection apparatus according to the present invention includes any one of the belt conveyance devices described above and a liquid ejection head that ejects liquid toward the conveyance medium that is conveyed on the conveyance belt.

  According to the liquid ejection apparatus of the present invention, even when the conveyance belt is contaminated by performing borderless printing, the contamination of the lower surface (non-printing surface) of the conveyance medium can be reduced.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a side view showing the overall configuration of an ink jet printer according to the present invention. As shown in FIG. 1, the inkjet printer 1 (liquid ejection device) is a color inkjet printer having four inkjet heads 2 (liquid ejection heads) and a belt conveying device 20. Further, the ink jet printer 1 includes a control unit 60 (see FIG. 2) for controlling the ink jet printer 1.

  The belt conveyance device 20 includes a paper feeding unit 11 on the left side in FIG. 1 and a paper discharge unit 12 on the right side in FIG. 1, and paper (conveyance medium) from the paper supply unit 11 toward the paper discharge unit 12. Is formed. A pair of feed rollers 5 a and 5 b that sandwich and convey a sheet are disposed immediately downstream of the sheet feeding unit 11. The paper is fed from the left to the right in FIG. 1 by the pair of feed rollers 5a and 5b. The sheet feeding unit 11 and the feed rollers 5a and 5b constitute a transport medium supply device.

  Two belt rollers 6 and 7 having rotation axes parallel to each other and an endless conveyor belt 8 wound around the rollers 6 and 7 are provided at an intermediate portion of the sheet conveyance path. ing. The outer peripheral surface 8a of the conveyance belt 8 is subjected to silicone treatment and has an adhesive force. A pressing roller 4 is disposed at a position facing the belt roller 7, and the sheet fed from the sheet feeding unit 11 by the feeding rollers 5 a and 5 b and fed through the guide 54 is sent to the outer peripheral surface of the conveying belt 8. 8a.

  A transport motor 9 is disposed below the transport belt 8, and a drive belt 10 is bridged between a shaft 9 a of the transport motor 9 and a shaft 6 a of the belt roller 6. As the rotation shaft 9a of the transport motor 9 rotates clockwise in FIG. 1, the belt roller 6 is rotationally driven clockwise. Then, the conveyance belt 8 stretched around the belt rollers 6 and 7 travels in the sheet conveyance direction (direction indicated by an arrow in FIG. 1) as the belt roller 6 rotates. In this way, the conveyance belt 8 holds the paper pressed against the outer peripheral surface 8a by the pressing roller 4 in a state where it is in contact with its adhesive force, and the downstream side is driven by the clockwise rotation of the belt roller 6 in FIG. Transport toward (right).

  A peeling mechanism 13 is provided immediately downstream of the conveying belt 8 along the sheet conveying path. The peeling mechanism 13 peels the paper adhered to the conveyance surface 8a of the conveyance belt 8 from the conveyance surface 8a and sends it to the discharge plate 55 provided in the right discharge unit 12 in FIG.

  Below the guide 54 (between the feed rollers 5a and 5b and the pressing roller 4) is a line for imaging the lower surface (non-printing surface) of the paper supplied from the paper supply unit 11 before being transported by the transport belt 8. An image sensor 51 (second imaging means) is provided. The guide 54 is provided with a window so that the line image sensor 51 can image the lower surface of the sheet.

  Below the discharge plate 55, a line image sensor 52 (first imaging means) that images the lower surface of the sheet after being transported by the transport belt 8 is provided. The discharge plate 55 is provided with a window so that the line image sensor 52 can image the lower surface of the sheet.

  An absorber 21 is disposed at a position obliquely below and to the right of the belt roller 6 so that the conveyor belt 8 is sandwiched between the belt roller 6 and is always in contact with the outer peripheral surface 8 a of the conveyor belt 8. The absorber 21 has a rectangular parallelepiped shape having a longitudinal direction in the direction perpendicular to the paper surface in FIG. 1, and the width in the longitudinal direction is substantially the same as the width of the conveying belt 8 (width in the direction perpendicular to the paper surface in FIG. 1). ing. The absorber 21 is connected to a tank (not shown) via an opening / closing valve 24 (see FIG. 2), and when the opening / closing valve 24 is set to the “open state” by a command from a determination unit 66 described later, A cleaning liquid is supplied to the absorber 21. On the other hand, when the on-off valve 24 is brought into the “closed state” by a command from the determination unit 66, the supply of the cleaning liquid to the absorber 21 is shut off. In this way, the absorbent body 21 absorbs the cleaning liquid and applies it to the outer peripheral surface 8 a of the transport belt 8.

  Downstream of the absorbent body 21 in the running direction of the conveyor belt 8 (downstream of the belt roller 6 and upstream of the belt roller 7 immediately upstream of the four inkjet heads 2); A blade 31 is disposed at a position diagonally to the left of the belt roller 6 so that the tip always contacts the outer peripheral surface 8 a of the conveyor belt 8. The blade 31 scrapes off the cleaning liquid or ink adhering to the outer peripheral surface 8 a of the conveyor belt 8 at the tip, and discards the scraped cleaning liquid or the like in a disposal unit 32 provided below the blade 31. As described above, the absorber 21, the blade 31, and the disposal unit 32 constitute a cleaning device 53 (cleaning unit) that cleans the outer peripheral surface 8a of the transport belt 8.

  The four inkjet heads 2 are arranged side by side along the paper transport direction corresponding to four color inks (magenta, yellow, cyan, and black). That is, the ink jet printer 1 is a line printer. Each of the four inkjet heads 2 has a head body 3 at the lower end thereof. The head main body 3 has an elongated rectangular parallelepiped shape that is long in a direction orthogonal to the paper transport direction (a direction perpendicular to the paper surface in FIG. 1). In addition, on the bottom surface of the head main body 3, a large number of nozzles having a small diameter for ejecting ink downward are arranged side by side, and this bottom surface is an ink ejection surface 3a facing the outer peripheral surface 8a.

  The head body 3 is disposed such that the ink discharge surface 3a and the outer peripheral surface 8a of the conveyor belt 8 on the ink jet head 2 side are parallel to each other, and a small amount of gap is formed between these surfaces. This gap portion constitutes a part of the paper transport path and serves as an image forming area on which paper is printed. With this configuration, when the paper transported on the transport belt 8 sequentially passes immediately below the four head bodies 3, ink of each color is ejected from the nozzles toward the upper surface of the paper, that is, the printing surface. Thus, a desired color image can be formed on the paper.

  Next, the control system of the inkjet printer 1 will be described with reference to FIG. FIG. 2 is a schematic block diagram showing a control configuration of the ink jet printer according to the present invention. The control unit 60 included in the inkjet printer 1 includes a CPU (Central Processing Unit) that is an arithmetic processing device, a ROM (Read Only Memory) that stores a control program executed by the CPU and data used for the control program. A RAM (Random Access Memory) for temporarily storing data during program execution.

  As shown in FIG. 2, the control unit 60 includes a head control unit 61, a conveyance control unit 62, a roller control unit 63, a reference image data acquisition unit 64, a captured image data acquisition unit 65, a determination unit 66, and a cleaning control unit 67. Have.

  When the control unit 60 receives a print signal from a PC (personal computer) 80, the head control unit 61 controls the head drive circuit 71 to eject ink from the corresponding inkjet head 2.

  When the control unit 60 receives a print signal from the PC 80, the transport control unit 62 drives the feed motor 14 to rotate both the feed rollers 5a and 5b so as to supply the paper onto the transport belt 8. The motor driver 72 is controlled.

  When the control unit 60 receives a print signal from the PC 80, the roller control unit 63 drives the transport motor 9 to rotate the belt roller 6 so that the paper on the transport belt 8 is transported in the paper transport direction. The motor driver 73 is controlled.

  The reference image data acquisition unit 64 acquires the image data of the lower surface of the paper before being conveyed by the conveyance belt 8 read by the line image sensor 51 as reference image data.

  The captured image data acquisition unit 65 acquires, as captured image data, image data of the lower surface of the sheet after being transported by the transport belt 8 read by the line image sensor 52.

  The determination unit 66 (determination means) compares the reference image data acquired by the reference image data acquisition unit 64 and the captured image data acquired by the captured image data acquisition unit 65 for each corresponding minute region. Here, the comparison is to measure the density for each pixel in a minute area corresponding to each of the reference image data and the captured image data. Then, the densities of all the pixels in the measured minute area are summed, and it is compared whether there is a difference of a predetermined value or more between the minute area of the reference image data and the minute area of the captured image data. If there is a difference greater than or equal to a predetermined value, it is determined that the minute area is dirty. The comparison is made in all the minute areas of the sheet, and the lower surface of the sheet is conveyed on the conveying belt 8 when the number of minute areas determined to be dirty exceeds a predetermined value (allowable upper limit level). It is determined that the transport belt 8 is soiled to the extent that the lower surface of the paper is soiled, and the transport control unit 62 stops the driving of the feed motor 14 and stops the rotation of the both feed rollers 5a and 5b. At the same time, the roller controller 63 stops the driving of the conveyance motor 9 to stop the rotation of the belt roller 6. That is, the conveyance control unit 62 constitutes a conveyance stop unit, and the roller control unit 63 constitutes a roller stop unit.

  In addition, the determination unit 66 determines the contamination level from the number of the dirty minute regions. Further, the determination unit 66 notifies the user that the lower surface of the sheet is dirty beyond the allowable upper limit level by the alarm device 74 (notification unit). The alarm device 74 may have any configuration as long as it notifies the user such as blinking a lamp (not shown) or generating an alarm sound.

  When the determination unit 66 determines that the lower surface of the sheet is dirty beyond the allowable upper limit level, the cleaning control unit 67 performs a cleaning device based on the cleaning time corresponding to the contamination level determined by the determination unit 66. 53, the outer peripheral surface 8a of the conveyor belt 8 is cleaned.

  Next, a series of operations for cleaning the outer peripheral surface 8a of the conveyor belt 8 will be described with reference to FIG. FIG. 3 is a flowchart for cleaning the outer peripheral surface 8 a of the conveyor belt 8.

  First, when the control unit 60 receives a print signal from the PC 80, the roller control unit 63 drives the conveyance motor 9 to cause the conveyance belt 8 to travel. Further, the conveyance control unit 62 drives the feed motor 14 to start supplying paper to the conveyance belt 8. Thereafter, the reference image data acquired by the reference image data acquisition unit 64 and the captured image data acquired by the captured image data acquisition unit 65 are compared for each corresponding micro area by the determination unit 66 (S1). When the number of minute areas determined to be dirty is equal to or less than the allowable upper limit level (S1: No), the outer peripheral surface 8a of the conveyor belt 8 is not dirty or is dirty enough not to stain the lower surface of the paper. Judge that there is, and continue printing. When the number of minute areas determined to be dirty by comparison exceeds the allowable upper limit level (S1: Yes), an alarm is generated by the alarm device 74, so that the outer peripheral surface 8a of the conveyor belt 8 is made to the user. Notify that it is dirty (S2). Further, driving of the feed motor 14 is stopped by the transport control unit 62, and driving of the transport motor 9 is stopped by the roller control unit 63. At this time, the rotation of both the feed rollers 5a and 5b is stopped (S3), and the rotation of the belt roller 6 is stopped (S4), so that the supply of the paper to the transport belt 8 and the transport of the paper by the transport belt 8 are stopped.

  Subsequently, the user selects whether to perform automatic cleaning or manual cleaning (S5). When performing manual cleaning (S5: No), when the casing (not shown) of the inkjet printer 1 is opened, the belt roller 6 is rotated by the roller control unit 63, and the transport belt 8 is traveled by a predetermined length. At this time, if the sheet remains on the conveyor belt 8, it is discharged and moved so that the dirty outer peripheral surface 8a of the conveyor belt 8 is positioned on the opening surface. Then, the outer peripheral surface 8a of the conveyor belt 8 is manually cleaned by the user (S7).

  When automatic cleaning is performed (S5: Yes), the cleaning device 53 performs automatic cleaning of the outer peripheral surface 8a of the transport belt 8 based on the cleaning time by the cleaning control unit 67 (S6). In this automatic cleaning, the rotational driving of the belt roller 6 is resumed with the feed rollers 5a and 5b stopped. The paper on the conveyor belt 8 is discharged. The rotation speed at this time is lower than the rotation speed during printing. In accordance with the start of rotation of the belt roller 6, the opening / closing valve 24 is opened, and a certain amount of cleaning liquid is supplied to the absorber 21. Thereafter, the open / close valve 24 is closed. When the belt roller 6 is rotated, the absorber 21 applies the cleaning liquid while sliding on the outer peripheral surface 8a of the conveyor belt 8. On the downstream side of the absorber 21, the blade 31 wipes off the ink adhering to the outer peripheral surface 8a together with the cleaning liquid. When cleaning is completed in this way, printing is automatically resumed (S8). Note that after the automatic cleaning is finished, the printing may be started after the manual cleaning is performed without automatically restarting the printing.

  According to the inkjet printer 1 described above, the reference image data that is the image data of the lower surface of the paper before being conveyed by the conveyance belt 8 acquired by the line image sensor 51, and the conveyance belt acquired by the line image sensor 52. 8 is compared with captured image data that is image data of the lower surface of the sheet after being transported by the sheet 8. As a result of this comparison, the stain on the lower surface of the sheet is detected from the number of minute areas determined to be dirty as a result of the comparison, so that the stain on the conveyor belt 8 can be detected quickly. Further, since the contamination of the conveyor belt 8 is not directly detected, the contamination of the conveyor belt 8 that does not contaminate the paper is not detected, but only the contamination of the conveyor belt 8 that contaminates the paper is detected. Therefore, unnecessary cleaning of the transport belt 8 and / or stop of the transport belt 8 can be minimized, and transport efficiency is improved. Even when the conveyance belt 8 is soiled by performing borderless printing or the like, the stain on the lower surface of the paper can be reduced.

  Further, the determination unit 66 can automate the determination regarding the contamination of the transport belt 8, thereby reducing the user's trouble. Further, the determination unit 66 compares the reference image data and the captured image data for each corresponding minute area, so that the dirty area of the conveyor belt 8 can be specified. Thus, it is advantageous to be able to identify a dirty area. For example, if a plurality of absorbers 21 are discretely arranged across the width direction of the conveyor belt 8, the cleaning liquid may be supplied only to the absorber 21 corresponding to the specified region, and the cleaning liquid is wasted. Is no longer used.

  Furthermore, by using the image of the lower surface of the sheet acquired by the line image sensor 51 as the reference image data, the determination accuracy is improved, for example, when a sheet with an original pattern is conveyed.

  In addition, since the alarm device 74 is provided, the user can deal with the detected dirt on the conveyor belt 8 with respect to his / her intention.

  When the determination unit 66 determines that the lower surface of the sheet is dirty beyond the allowable upper limit level, the conveyance control unit 62 stops the rotation of the both feed rollers 5a and 5b, and the roller control unit 63 By stopping the rotation of the belt roller 6, new paper is not supplied, and it is possible to reliably prevent the newly supplied paper from becoming dirty beyond the allowable upper limit level.

  Furthermore, the dirty conveying belt 8 can be cleaned by having the cleaning device 53. At this time, the cleaning control unit 67 determines the cleaning time corresponding to the level of dirt on the lower surface of the paper determined by the determination unit 66, so that the cleaning execution time can be made appropriate.

  Next, modified examples in which various modifications are added to the above-described embodiment will be described. However, about the thing which has the structure similar to this embodiment mentioned above, the same code | symbol is attached | subjected and the description is abbreviate | omitted suitably.

  In the embodiment described above, as shown in FIG. 3, when it is determined that the outer peripheral surface 8a of the conveyor belt 8 is dirty (S1: Yes), the user always selects automatic cleaning or manual cleaning. However, the user may confirm whether or not to perform cleaning, and automatic cleaning or manual cleaning may be performed according to the user's judgment. For example, as shown in FIG. 4, when it is determined that the outer peripheral surface 8a of the conveyor belt 8 is dirty (S101: Yes), the user is notified that the outer peripheral surface 8a of the conveyor belt 8 is dirty (S102). At the same time, the rotation of both the feed rollers 5a and 5b and the rotation of the belt roller 6 are stopped (S103, S104), and the printing is stopped. Then, the user visually confirms the lower surface of the printed paper immediately before stopping printing (S105). If it is determined that cleaning is necessary (S106: Yes), a cleaning method is selected (S107), automatic cleaning (S108) or manual cleaning (S109) is performed, and printing may be resumed (S110).

  As shown in FIG. 5, when it is determined that the outer peripheral surface 8a of the conveyor belt 8 is dirty (S201: Yes), the user is notified that the outer peripheral surface 8a of the conveyor belt 8 is dirty (S202). . At this time, the printing is continued without stopping the rotation of the both feed rollers 5a and 5b and the rotation of the belt roller 6. Then, the user visually confirms the lower surface of the printed paper immediately before the notification (S203). If it is determined that cleaning is necessary (S204: Yes), the rotation of the feed rollers 5a and 5b and the rotation of the belt roller 6 are stopped (S205, S206), the cleaning method is selected (S207), and the automatic cleaning is performed. (S208) or manual cleaning (S209) may be performed to resume printing (S210).

  Further, in the above-described embodiment, when it is determined that the conveyor belt 8 is dirty, the user selects whether to perform automatic cleaning or manual cleaning every time. May be selected.

  Furthermore, in the above-described embodiment, the determination unit 66 determines whether or not the lower surface of the sheet is dirty beyond the upper limit level. However, if only the state of the lower surface of the sheet is detected, the determination unit 66 66, the roller control unit 63 and the conveyance control unit 64 may not be provided.

  In addition, in the above-described embodiment, the image of the lower surface of the paper acquired by the line image sensor 51 is used as the reference image data. However, by storing the lower surface of the paper as the reference image data in advance, the line image sensor 51 may not be provided.

  In the above-described embodiment, the cleaning device 53 is provided. However, if the cleaning is performed manually, the cleaning device 53 may not be provided.

  Further, in the above-described embodiment, the supply of paper from the paper supply unit 11 is stopped by the roller control unit 63 and the conveyance control unit 64. However, even if only the conveyance control unit 64 is provided, the paper supply unit 11 is provided. The paper supply from can be stopped.

  In addition, in the embodiment described above, the cleaning control unit 67 sets the cleaning time based on the contamination level determined by the determination unit 66. However, the cleaning control unit 67 is not provided, and the conveyance belt 8 is contaminated. A sufficient cleaning time that can be removed may be fixed.

  In the above-described embodiment, when one wide endless belt is used as the conveyor belt 8, the line image sensor 51 that acquires the reference image data and the line image sensor 52 that acquires the captured image data are arranged in the conveyor direction. It is preferable to arrange a plurality of positions corresponding to each of the positions easily contaminated. For example, the sensors 51 and 52 are arranged corresponding to both ends in the width direction of the paper when performing borderless printing. Thereby, it is possible to accurately know the degree of dirt on the back side of the paper.

  In the above-described embodiment, when a plurality of endless belts are used as the conveyor belt 8, the line image sensor 51 that acquires the reference image data and the line image sensor 52 that acquires the captured image data are either It is good to arrange on the extension line of the endless belt. At this time, as the endless belt, it is preferable to select a belt in a position where it is easily soiled by printing. Thereby, only the dirty endless belt can be reliably cleaned. In addition, the load on the drive source can be reduced, and the amount of cleaning liquid used can be reduced. Of course, both sensors 51 and 52 may be arranged in correspondence with each endless belt in the transport direction. At this time, only the dirty endless belt can be cleaned by individually arranging the cleaning devices 53 (the absorber 21 and the blade 31) corresponding to each endless belt.

  In the above-described embodiment, the line image sensor 52 is disposed below the discharge plate 55. However, the line image sensor 52 may be disposed below the separation mechanism 13 positioned upstream and across the separation mechanism 13 and the discharge plate 55. good. When the peeling mechanism 13 and the discharge plate 55 are separated from each other, they may be disposed between them. As a result, the contamination of the conveyor belt 8 can be known at an early timing.

  In the above-described embodiment, the absorber 21 and the blade 31 constituting the cleaning device 53 are arranged so as to always scrutinize the outer peripheral surface 8a of the conveyance belt 8. The rubbing by the absorber 21 and the blade 31 creates resistance against the rotational driving of the belt roller 6. If the driving force of the driving source does not have a margin, it is better to scrutinize only when cleaning is performed. This reduces the load on the drive source. Further, the life of the absorber 21 and the blade 31 can be extended.

  The present invention is not limited to the ink jet printer as in the above-described embodiment, and can be applied to various apparatuses as long as it is a belt conveying apparatus.

1 is a side view illustrating an overall configuration of an inkjet printer according to an embodiment of the present invention. It is a schematic block diagram which shows the control structure of the inkjet printer which concerns on this invention. 4 is a flowchart for cleaning the outer peripheral surface 8a of the conveyor belt 8. It is a flowchart which performs cleaning by automatically stopping printing according to a modification. It is a flowchart which performs printing by manually stopping printing according to another modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet printer 2 Inkjet head 5a, 5b Feed roller 6,7 Belt roller 8 Conveying belt 8a Outer peripheral surface 11 Paper feeding part 20 Belt conveying apparatus 51,52 Line image sensor 53 Cleaning apparatus 60 Control part 62 Conveyance control part 63 Roller control part 66 Judgment Unit 67 Cleaning Control Unit 74 Alarm Device

Claims (9)

Two rollers having rotational axes parallel to each other;
A conveyor belt that is wound around the two rollers and has an outer peripheral surface that conveys the conveyance medium while contacting the lower surface of the conveyance medium as the two rollers rotate.
First imaging means for imaging the lower surface of the transport medium after being transported by the transport belt ;
Determination means for determining whether or not the lower surface of the transport medium is soiled exceeding an allowable upper limit level based on a lower surface image obtained by the first imaging means ;
Whether the lower surface of the transport medium is soiled beyond the allowable upper limit level based on the determination means comparing the lower surface image with a reference image having the same size for each corresponding minute region. belt conveying device, characterized in that to determine. A second imaging means for imaging the lower surface of the conveyance medium before being conveyed by the conveyance belt;
It said determination means, a belt conveying device according to claim 1, characterized in that use an image obtained by the second imaging means as the reference image. 3. The information processing apparatus according to claim 1, further comprising a notification unit that notifies the user when the determination unit determines that the lower surface of the transport medium is dirty beyond the allowable upper limit level. The belt conveyance apparatus as described in. 2. The apparatus according to claim 1, further comprising: a roller stop unit that stops the rotation of the two rollers when the determination unit determines that the lower surface of the transport medium is dirty beyond the allowable upper limit level. The belt conveyance apparatus of any one of 1-3 . A transport medium supply device that supplies the transport medium to the transport belt on the upstream side in the transport direction in which the transport medium is transported;
2. The apparatus according to claim 1, further comprising a conveyance stop unit that stops the conveyance medium supply device when the determination unit determines that the lower surface of the conveyance medium is dirty beyond the allowable upper limit level. The belt conveyance apparatus of any one of 1-4 . Belt conveyor device according to any one of claims 1 to 5, characterized in that it further comprises a cleaning means for cleaning the outer circumferential surface of the conveyor belt. The cleaning unit automatically cleans the outer peripheral surface of the transport belt when the determination unit determines that the lower surface of the transport medium is dirty beyond the allowable upper limit level. Item 7. The belt conveying device according to Item 6 . Two rollers having rotational axes parallel to each other;
A conveyor belt that is wound around the two rollers and has an outer peripheral surface that conveys the conveyance medium while contacting the lower surface of the conveyance medium as the two rollers rotate.
First imaging means for imaging the lower surface of the transport medium after being transported by the transport belt;
Determination means for determining whether or not the lower surface of the transport medium is soiled exceeding an allowable upper limit level based on a lower surface image obtained by the first imaging means;
Cleaning means for cleaning the outer peripheral surface of the conveyor belt,
The cleaning unit automatically cleans the outer peripheral surface of the transport belt when the determination unit determines that the lower surface of the transport medium is dirty beyond the allowable upper limit level,
The determination means determines a contamination level when the lower surface of the conveyance medium is dirty exceeding an allowable upper limit level,
The belt conveyance device further comprising: a cleaning control unit that controls a cleaning time of the outer peripheral surface of the conveyance belt by the cleaning unit based on a dirt level determined by the determination unit. The belt conveyance device according to any one of claims 1 to 8 ,
A liquid ejection apparatus comprising: a liquid ejection head that ejects liquid toward the conveyance medium being conveyed on the conveyance belt.

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