JP6114059B2 - Printing device - Google Patents

Description

  The present invention relates to a printing apparatus that performs printing on a sheet, and more particularly, to a printing apparatus that appropriately cleans a conveyance roller.

  In general, an ink jet printing apparatus to which an ink jet method is applied is configured to eject ink from nozzles of an ink jet head based on print data such as image information and character information on a sheet conveyed by a conveyance roller. Print characters.

  As described above, in a printing apparatus that prints on a sheet to be transported, the sheet is transported by the transport roller. Therefore, the ink on the printed sheet may be transferred to the transport roller and the transport roller may become dirty.

  Patent Document 1 proposes an image forming apparatus that cleans a conveyance path.

  In this image forming apparatus, a light amount detection unit that detects light transmitted through the transparent guide member is provided in the conveyance path, and the degree of contamination of the conveyance path is determined from the light transmission amount of the transparent guide member of the light amount detection unit. If the degree of contamination on the conveyance path is greater than or equal to the predetermined degree of dirt, the sheet conveyance motor is driven so that the cleaning sheet in the cleaning sheet cassette is circulated through the conveyance path and the reverse conveyance path while being transparent at the light amount detection unit. The amount of light transmitted through the guide member is detected. Then, the control unit circulates the cleaning sheet through the conveyance path and the reverse conveyance path until the light amount detected by the light amount detection unit rises to the predetermined light amount, and when the detection light amount of the light amount detection unit rises to the predetermined light amount, It is determined that the path has been cleaned, the cleaning sheet is discharged, and the cleaning operation is terminated.

Japanese Patent Laid-Open No. 11-116087

  In the image forming apparatus described in Patent Document 1, when the cleaning sheet is circulated through the conveyance path and the reverse conveyance path, and the amount of light transmitted through the transparent guide member installed in the conveyance path rises to a predetermined amount, the conveyance path is cleaned. The cleaning sheet is discharged. That is, the image forming apparatus described in Patent Document 1 does not detect the degree of contamination of the cleaning sheet itself or the change thereof.

  When the cleaning sheet for removing dirt on the conveyance path is used for cleaning, the cleaning sheet itself becomes dirty, so that the ability to remove dirt is reduced. Therefore, unless the cleaning sheet itself is detected to be dirty, it cannot be determined whether or not the dirt removal capability remains on the cleaning sheet being circulated and conveyed.

  The image forming apparatus described in Patent Document 1 circulates and conveys the next cleaning sheet when the predetermined amount of light is not reached by the first cleaning sheet, but discharges the cleaning sheet from which dirt has been wiped off. The timing is determined by whether or not the number of circulating conveyances reaches a predetermined number of circulations. However, since the cleaning sheet is discharged only by the circulation number, the cleaning sheet is continuously circulated even when the removal capability is lost before the circulation number is reached. As a result, the time required for cleaning becomes longer, and the apparatus cannot be used during this time, which may be inconvenient for the user.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a printing apparatus that appropriately cleans the conveying means.

    In order to achieve the above object, a first feature of a printing apparatus according to the present invention is that a sheet feeding unit that supplies a medium placed on a sheet feeding table to a circulation conveyance path, and a medium that is supplied by the sheet feeding unit. Conveying means for conveying the medium on the circulation conveyance path, printing means for performing a printing process on a medium conveyed by the conveyance means, and a medium subjected to the printing process by the printing means and discharged from the circulation conveyance path A paper discharge means for placing the paper, a dirt detection means for detecting the degree of dirt on the medium transported by the conveyance means, and the degree of dirt detected by the dirt detection means is a predetermined upper limit. An upper limit determining means for determining whether or not a value has been exceeded, a difference determining means for determining whether or not a difference between the previous and current dirt levels detected by the dirt detecting means is smaller than a predetermined threshold, and the conveying means of When the leaning process is requested, the medium is fed to the sheet feeding unit, and the medium is circulated and conveyed on the conveying unit without performing the printing process by the printing unit, and the cleaning process of the conveying unit is performed. A control unit that executes the medium that is circulated and conveyed, and the control unit has a stain degree exceeding a predetermined upper limit value by the upper limit determination unit when the cleaning process is started. If the difference determining unit determines that the difference in the degree of contamination is smaller than a predetermined threshold, the medium conveyed through the circulation conveyance path is discharged to the sheet discharging unit and cleaned. When the processing is finished and the upper limit determination unit determines that the degree of contamination exceeds a predetermined upper limit value, the medium conveyed through the circulation conveyance path is transferred to the discharge unit. With discharging, it is a new medium from said feeding means to continue the circulation is supplied to the transport cleaning process.

  A second feature of the printing apparatus according to the present invention is that the control unit further determines in advance that the difference determination unit determines that the difference between the previous and current stain levels is smaller than a predetermined threshold value. When the occurrence occurs continuously a number of times, the medium conveyed through the circulation conveyance path is discharged to the discharge unit.

  According to the first feature of the printing apparatus according to the present invention, when the control unit starts cleaning the transport unit, the upper limit determination unit determines that the degree of contamination does not exceed a predetermined upper limit value. When the difference determination unit determines that the difference between the previous and current stain levels is smaller than a predetermined threshold, the medium conveyed on the circulation transport path is discharged to the sheet discharge unit, and the stain level is determined by the upper limit determination unit. When it is determined that the upper limit of the medium is exceeded, the medium conveyed through the circulation conveyance path is discharged to the sheet discharge means, and the medium is supplied from the sheet supply means to the circulation conveyance path. For this reason, when the change in the contamination of the medium becomes sufficiently small even though the ability to remove the dirt on the medium is sufficient, it can be determined that the conveying means has been sufficiently cleaned and the ability to remove the dirt on the medium is limited. Since the cleaning is performed with a new sheet when reaching the above, the conveying means can be appropriately cleaned.

  According to the second feature of the printing apparatus according to the present invention, the control unit further determines in advance that the difference determination unit determines that the difference between the previous and current stain levels is smaller than a predetermined threshold value. When the occurrence occurs continuously, the medium conveyed through the circulation conveyance path is discharged to the paper discharge unit, so that the transfer unit can be cleaned with higher accuracy.

1 is a diagram illustrating an outline of an inkjet printing apparatus 100 according to an embodiment of the present invention. It is the figure which showed the function structure of the inkjet printing apparatus 100 which is one Embodiment of this invention. It is the flowchart explaining the process sequence of the inkjet printing apparatus 100 which is one Embodiment of this invention. FIG. 6 is a diagram illustrating the number of times a sheet is detected by a sheet detection unit and the degree of stain detected by the sheet detection unit in the inkjet printing apparatus 100 according to an embodiment of the present invention.

  Embodiments of the present invention will be described with reference to the drawings.

<Configuration of inkjet printing apparatus>
In one embodiment of the present invention, black or color ink is ejected from nozzles of an inkjet head based on print data such as image information and character information on a sheet conveyed through a circulation conveyance path by rotation driving of a conveyance roller. An ink jet printing apparatus that prints images and characters will be described as an example.

  FIG. 1 is a diagram showing an outline of an inkjet printing apparatus according to an embodiment of the present invention.

  As shown in FIG. 1, the inkjet printing apparatus 100 displays, for example, a menu or starts printing based on a control unit 10 including a controller board on which a CPU and the like are arranged and a user operation. And an operation panel 50 that supplies operation signals for requesting various operations to the control unit 10.

  In addition, the inkjet printing apparatus 100 serves as a paper feed mechanism that supplies the paper P. The side paper feed stand 320 exposed outside the side surface of the housing and a plurality of paper feed trays (330a, 330b) provided inside the housing. , 330c, 330d).

  Then, the paper P fed one by one from the paper feed mechanism of either the side paper feed tray 320 or the paper feed tray 330 is fed into a paper feed transport path FR (black in the figure) by a drive mechanism such as a roller. (Bold line) and guided to the resist portion Rg. Here, the registration unit Rg is provided to perform alignment and skew correction of the leading edge of the paper P, and includes a pair of registration rollers 350. The fed paper P is temporarily stopped by the registration unit Rg for skew correction, and is conveyed toward the printing mechanism at a predetermined timing.

  Therefore, a junction point where the conveyance path of the fed paper P and the path on which the paper P on which one side is printed is circulated is merged exists in front of the registration unit Rg in the conveyance direction. To do. Based on this merging point, the path on the paper feed mechanism side is referred to as a paper feed conveyance path FR, and the other path is referred to as a circulation conveyance path CR.

  A plurality of inkjet heads 130 are provided further on the conveyance direction side of the registration portion Rg on the circulation conveyance path CR, and C (cyan), M (magenta), Y (yellow), They are arranged in the order of K (black). The color order is not limited to this order, and each user may set an optimal order as appropriate. The printing paper is printed line by line with ink ejected from each inkjet head 130 while being conveyed at a speed determined by printing conditions by an annular conveyance belt 360 provided on the opposite surface of the inkjet head 130. The ink jet head 130 corresponds to the printing means in the claims.

  A sheet detection unit 110 is provided between the registration unit Rg on the circulation conveyance path CR and the inkjet head 130.

  The paper detection unit 110 has a scanner (CIS: Contact Image Sensor) in which a plurality of image pickup devices are arranged in a direction orthogonal to the conveyance direction of the paper P, and detects dirt on the paper P by the output of the scanner. To do. In addition, the paper detection unit 110 detects an end in the direction orthogonal to the conveyance direction of the paper P conveyed to the inkjet head 130 and its position, and outputs the detected position to the control unit 10. Based on this detection result, the nozzle of the inkjet head 130 used for the printing process is determined by the control unit 10. In addition, the paper detection unit 110 can detect the leading end of the paper P in the transport direction, and can be used for adjusting the timing of starting recording by the inkjet head 130, or can detect whether the front end of the paper is bent or not.

  A suction fan 370 is provided inside the transport belt 360. A large number of air holes are formed on the surface of the conveyance belt 360, and the printing paper is adsorbed to the conveyance belt 360 and conveyed by the suction force generated by the rotation of the suction fan 370.

  The printed paper P is further transported in the housing by a driving mechanism such as transport rollers 390 provided at a plurality of locations in the circulation transport path CR.

  The transport roller 390 is mechanically connected to a drive motor (not shown) serving as a drive source, and includes a drive roller 390a that rotates by driving of the drive motor, and a driven roller 390b that rotates by pressure contact with the drive roller 390a. The paper P is transported on the circulation transport path CR at a predetermined transport speed by rotating the driving roller 390a and the driven roller 390b in pressure contact with each other.

  In the case of single-sided printing in which printing is performed only on one side of the paper P, the paper P is directly guided to the paper discharge port 340 to be discharged, and is printed on a paper discharge table 345 provided as a receiving table for the paper discharge port 340. Loaded with the side down. The paper discharge table 345 has a tray shape protruding from the casing, and has a certain thickness. The paper discharge table 345 is inclined, and the paper P discharged from the paper discharge port 340 and slid along the inclination is naturally arranged and overlapped by a wall formed at a lower position of the inclination. ing.

  In the case of double-sided printing in which printing is performed on both sides of the paper P, the front side (the first printed side is “front side” and the next printed side is “back side”) is not guided to the paper discharge port 340 at the end of printing. In addition, it is transported in the housing. For this reason, the inkjet printing apparatus 100 includes a switching mechanism 380 for switching the conveyance path for backside printing. The paper P that has not been guided to the paper discharge port 340 by the switching mechanism 380 is drawn into the switchback path SR, and is switched back, so that the front and back are reversed with respect to the transport path. Then, it is guided again to the registration portion Rg by a driving mechanism such as a roller and temporarily stops for skew correction. Thereafter, the sheet is conveyed in the direction of the printing mechanism at a predetermined timing, and the back side is printed by the same procedure as that for the front side. The paper P on which the back side has been printed and images are formed on both sides is again transported in the housing by a driving mechanism such as transport rollers 390 provided at a plurality of locations on the circulation transport path CR.

  At this time, the ink ejected from each inkjet head 130 onto the paper P may be transferred to the transport roller 390 or the like. Then, when the ink transferred to the transport roller 390 is retransferred to the next transported paper P, the paper P becomes dirty.

  The paper P transported by the transport roller 390 is guided to the paper discharge port 340 and discharged, and is stacked on a paper discharge table 345 provided as a receiving base for the paper discharge port 340.

<Functional Configuration of Inkjet Printing Apparatus 100>
Next, the functional configuration of the inkjet printing apparatus 100 according to an embodiment of the present invention will be described.

  FIG. 2 is a diagram illustrating a functional configuration of the inkjet printing apparatus 100 according to the embodiment of the present invention.

  As shown in FIG. 2, the inkjet printing apparatus 100 includes a control unit 10, an operation panel 50, a registration roller 350 of the registration unit Rg, a paper detection unit 110, a conveyance roller 390, a side paper feed table 320, A plurality of paper feed trays (330a, 330b, 330c, 330d) and a switching mechanism 380 are provided. Among these configurations, the side paper feed tray 320, the plurality of paper feed trays (330a, 330b, 330c, 330d), and the switching mechanism 380 have been described above, and thus description thereof is omitted. In addition, the area | region shown to 101 in the figure has shown the top view of the registration roller 350 of the registration part Rg, the paper detection part 110, and the conveyance roller 390. FIG.

  As indicated by 101 in the figure, a sheet detection unit 110 is provided on the conveyance direction side of the registration unit Rg on the circulation conveyance path CR, and a conveyance roller 390 is further provided on the conveyance direction side of the sheet detection unit 110. ing.

  The registration roller 350 of the registration portion Rg has a cylindrical shape made of rubber or resin, and minute irregularities are formed on the outer peripheral surface by ceramic particles to prevent slippage and to make transfer dirt inconspicuous ( In other words, it has a roller 350b, a roller 350c, a roller 350d, a roller 350e, and a roller 350f (with ceramic coating), and these rollers are provided with a direction orthogonal to the transport direction of the paper P as a rotation axis. It is fixed to the shaft 350a.

  Thus, the roller 350b, the roller 350c, the roller 350d, the roller 350e, and the roller 350f that are in contact with the paper P are provided on the shaft 350a, so that the ink transferred to the registration roller 350 is transported next. When retransferred to P, the ink is retransferred to the positions of P101, P102, P104, P106, and P107 corresponding to the positions of the rollers 350b, 350c, 350d, 350e, and 350f, respectively.

  Similarly, the transport roller 390 has a cylindrical shape made of rubber or resin, and has rollers 390s and 390t in which fine particles of anti-slip ceramic particles are formed on the outer peripheral surface. These rollers are fixed to a shaft 390r provided with a direction orthogonal to the conveyance direction of the paper P as a rotation axis. Note that the drive side of the transport roller 390 (the upper right roller in FIG. 1) does not come into contact with the surface on which the paper P is printed by reversing the front and back, and therefore may not be ceramic coated.

  Thus, since the shaft 390r is provided with the rollers 390s and 390t that come into contact with the paper P, when the ink transferred to the transport roller 390 is transferred again to the paper P to be transported next, the roller 390s. , 390t, the ink is retransferred to the positions of P103 and P105 corresponding to the positions of 390t.

  The operation panel 50 includes a display / input panel (not shown), a start key for starting reading and printing, a stop key for stopping reading and printing, a numeric keypad for inputting the number of prints, etc. And an operation signal based on a user operation is supplied to the control unit 10.

  The display / input panel of the operation panel 50 includes a pressure-sensitive or electrostatic transparent touch panel disposed on the front surface and a liquid crystal display panel disposed on the back surface of the touch panel for displaying various display screens (none of which are shown). ). The user touches the surface of the touch panel directly with his / her finger while looking at the display screen of the liquid crystal display panel, thereby depressing various buttons such as a roller cleaning button for requesting cleaning of the roller displayed on the display screen. It can be carried out.

  The control unit 10 performs central control of the inkjet printing apparatus 100. The control unit 10 includes an upper limit determination unit 11, an upper limit value storage unit 12, a difference determination unit 13, a dirt value storage unit 14, a dirt position determination unit 15, a roller position information storage unit 16, and a device control. Unit 17.

  The upper limit determination unit 11 determines whether the stain detected by the paper detection unit 110 exceeds a predetermined upper limit value Dth.

  The upper limit storage unit 12 stores an upper limit value Dth.

  The difference determination unit 13 determines whether or not the change in the stain degree D detected by the paper detection unit 110 is smaller than the stain degree difference threshold ΔDth that is a predetermined threshold. More specifically, the difference determination unit 13 extracts the difference between the previously measured stain condition stored in the stain value storage unit 14 and the stain degree measured this time, and this difference is smaller than the difference threshold ΔDth. It is determined whether or not.

  The stain value storage unit 14 stores the stain degree D detected by the paper detection unit 110, the counter value, and the stain degree difference threshold ΔDth.

  The roller position information storage unit 16 stores P101, P102, P104, P106, and P107 as the position of the registration roller 350 of the registration unit Rg, and P103 and P105 as the positions of the transport roller 390 as roller position information.

  The smear position determination unit 15 uses the position of the registration roller 350 or the conveyance roller 390 of the registration unit Rg stored in the roller position information storage unit 16 in the direction orthogonal to the conveyance direction of the circulation conveyance path CR, and the sheet detection unit 110. Based on the detected dirt position, it is determined which of the registration rollers 350 or the transport rollers 390 of the registration unit Rg is dirty. For example, when the positions of the stains detected by the paper detection unit 110 are P101 and P102, the registration unit Rg is contaminated based on the roller position information stored in the roller position information storage unit 16. The registration roller 350 is determined.

  When the cleaning process is started, the device control unit 17 determines that the stain level does not exceed the predetermined upper limit value Dth by the upper limit determination unit 11, and the difference determination unit 13 sets the stain level difference to the stain level difference. When it is determined that it is smaller than the threshold value ΔDth, by switching the switching mechanism 380, the sheet P conveyed on the circulation conveyance path CR is discharged to the discharge table 345, and the cleaning process is ended.

  In addition, when the difference determination unit 13 determines that the difference in the contamination level is smaller than the contamination level difference threshold ΔDth, the device control unit 17 causes the circulation conveyance path CR to pass through the circulation conveyance path CR. The conveyed paper P may be discharged onto the paper discharge tray 345.

  Furthermore, when the upper limit determination unit 11 determines that the stain detected by the paper detection unit 110 has exceeded the predetermined upper limit value Dth, the device control unit 17 switches the switching mechanism 380 to change the circulation conveyance path CR. Paper P is discharged to a paper discharge tray 345, and the paper P before use is 1 from either the side paper feed tray 320 or a plurality of paper feed trays (330a, 330b, 330c, 330d). The sheet is fed and the cleaning process is continued.

<Operation of Inkjet Printing Apparatus 100>
Next, the operation of the inkjet printing apparatus 100 according to an embodiment of the present invention will be described. FIG. 3 is a flowchart illustrating the processing procedure of the inkjet printing apparatus 100 according to an embodiment of the present invention.

  As shown in FIG. 3, the control unit 10 determines whether roller cleaning is requested (step S100). Specifically, when a roller cleaning button for requesting roller cleaning processing is pressed by a user operation from the display / input panel of the operation panel 50, it is determined that roller cleaning is requested. As a result, a cleaning operation is started in which cleaning is performed by transporting the paper P along the circulation transport path CR.

  In step S100, when roller cleaning is requested (S100; YES), the control unit 10 controls the paper from either the side paper feed tray 320 or the plurality of paper feed trays (330a, 330b, 330c, 330d). One sheet of P is fed (step S110).

  Next, the upper limit determination unit 11 of the control unit 10 determines whether or not the stain degree D detected by the paper detection unit 110 exceeds a predetermined upper limit value Dth (step S120).

  FIG. 4 is a diagram illustrating determination processing by the control unit 10 in the inkjet printing apparatus 100 according to the embodiment of the present invention. In FIG. 4, the number of times the paper P is detected by the paper detection unit 110 is shown on the x axis, and the degree of dirt (stain degree) D detected by the paper detection unit 110 is shown on the y axis. Here, Dth is an upper limit value of the degree of stain, and indicates the stain at the use limit, which is the limit of the stain removal capability of the paper P. That is, when the degree of contamination of the paper P reaches the upper limit value Dth, the capability of removing the contamination of the paper P is low, and the contamination of the roller cannot be removed even if the paper P is further conveyed, so that the paper P needs to be replaced.

  As shown in FIG. 4, the stain degree 201 has reached the upper limit value Dth at the fourth time, and the paper P may need to be replaced in order to remove the stain on the roller. Recognize.

  Returning to FIG. 3, when it is determined in step S120 that the stain degree D detected by the paper detection unit 110 exceeds the predetermined upper limit value Dth (S120; YES), the paper P is at the limit of the stain removal capability. Since the usage limit is exceeded, the device control unit 17 discharges the paper P (step S130). Specifically, the device control unit 17 switches the switching mechanism 380 so that the paper P is guided to the paper discharge port 340. As a result, the paper P is guided to the paper discharge port 340 and discharged, and is stacked on a paper discharge table 345 provided as a receiving base for the paper discharge port 340.

  Then, the process proceeds to step S110, and the control unit 10 feeds one sheet of paper P from either the side paper feed tray 320 or the plurality of paper feed trays (330a, 330b, 330c, 330d).

  On the other hand, if it is determined in step S120 that the stain degree D detected by the paper detection unit 110 does not exceed the predetermined upper limit value Dth (S120; NO), the difference determination unit 13 calculates the stain degree difference ΔD. (Step S140). Specifically, the difference determination unit 13 stores the value of the degree of stain D detected by the paper detection unit 110 in the stain value storage unit 14 as the current value, and the previous value stored in the stain value storage unit 14. A value of a certain degree of dirt D is extracted. Then, the difference determination unit 13 calculates the difference between the previous value and the current value as the stain degree difference ΔD.

  Next, the difference determination unit 13 determines whether or not the stain degree difference ΔD is smaller than the stain degree difference threshold ΔDth (step S150).

In the example shown in FIG. 4, the change in the degree of contamination 203 is gradually reduced. That is, the degree of dirt and fourth and fifth degree of dirt and the difference [Delta] D _{1, fifth} and dirt degree difference [Delta] D 2 of the _{sixth, sixth} and dirt degree difference [Delta] D 3 and 7 _{th, 7} th and 8 th The difference ΔD ₄ is gradually reduced, and it is assumed that the following inequality sign is established.

ΔD ₁ > ΔD ₂ > ΔD ₃ >ΔDth> ΔD ₄ (Equation 1)
At this time, in the eighth time, the difference determination unit 13 determines that the contamination degree difference ΔD is smaller than the contamination degree difference threshold ΔDth.

  Returning to FIG. 3, if it is determined in step S150 that the stain degree difference ΔD is greater than or equal to the stain degree difference threshold ΔDth (S150; NO), it can be determined that the change in the stain on the paper P is large. That is, since it can be determined that the stain can still be removed by the paper P, after the difference determination unit 13 resets the counter (step S155), the device control unit 17 circulates and conveys the paper P by a driving mechanism such as the conveyance roller 390. The road CR is circulated (step S160).

  On the other hand, if it is determined in step S150 that the stain degree difference ΔD is smaller than the stain degree difference threshold ΔDth (S150; YES), the difference determination unit 13 continues N times and the stain degree difference ΔD is changed to the stain degree difference. It is determined whether or not it is determined that it is smaller than the threshold value ΔDth (step S170).

  In step S170, when it is determined that N times are not continuous (S170; NO), the counter is incremented by “1” and stored in the dirt value storage unit 14 (step S180).

  On the other hand, when it is determined in step S170 that the stain degree difference ΔD is smaller than the stain degree difference threshold ΔDth for N consecutive times (S170; YES), the difference determination unit 13 resets the counter (step S190). After completing the cleaning process, the device control unit 17 discharges the paper P (step S200).

  In this manner, the upper limit determination unit 11 determines that the stain degree D detected by the paper detection unit 110 does not exceed the predetermined upper limit value Dth in step S120, and the difference determination unit 13 continues N times. When it is determined that the stain degree difference ΔD is smaller than the stain degree difference threshold ΔDth, the change in the stain on the paper P is sufficiently small even though the stain removal capability of the paper P is sufficient. It can be determined that the cleaning was sufficient.

As mentioned above, according to the inkjet printing apparatus 100 which is one Embodiment of this invention,
A transport roller 390 that is provided on the circulating transport path CR and transports the supplied paper P on the circulating transport path CR, and a sheet P that is connected to the circulating transport path CR and discharged from the circulating transport path CR is placed. A paper discharge table 345 that is provided on the circulation conveyance path CR, detects the degree of contamination of the paper P conveyed by the conveyance roller 390, and the degree of contamination detected by the paper detection unit 110 is a predetermined level. An upper limit determination unit 11 that determines whether or not the upper limit value has been exceeded, a difference determination unit 13 that determines whether or not a change in the degree of contamination detected by the paper detection unit 110 is smaller than a predetermined threshold, and a cleaning process are started. Then, the upper limit determination unit 11 determines that the degree of contamination does not exceed a predetermined upper limit value, and the difference determination unit determines that the difference in the degree of contamination is smaller than a predetermined threshold value. In this case, when the paper P conveyed on the circulation conveyance path CR is discharged to the paper discharge tray 345 to finish the cleaning process, and the upper limit determination unit 11 determines that the degree of contamination exceeds a predetermined upper limit value, The paper P conveyed on the circulation conveyance path CR is discharged to the paper discharge tray 345, and a new paper P is fed from either the side paper feed tray 320 or the plurality of paper feed trays (330a, 330b, 330c, 330d). Since the apparatus control unit 17 is provided to be supplied to the circulation conveyance path CR and to continue the cleaning process, the conveyance roller can be appropriately cleaned.

  In the inkjet printing apparatus 100 according to the embodiment of the present invention, cleaning is performed by transporting the paper P through the circulation transport path CR. However, the paper P may be plain paper or thick paper. It may also be a cleaning sheet dedicated to cleaning.

  Further, in the embodiment of the present invention, the ink jet type ink jet printing apparatus 100 that performs printing in line units has been described as an example. However, the present invention is not limited to this, and a serial ink jet method, a laser method, a stencil printing method, etc. It may be a printing device.

  Further, the registration roller 350 has been described as having an outer peripheral surface coated with ceramic. However, since the registration roller 350 is located farthest from the inkjet head 130 in the conveyance direction of the printed paper and is the most difficult to accumulate dirt among the rollers in the apparatus, the registration roller 350 may not be ceramic coated.

CR: Circulation conveyance path FR: Paper feed conveyance path Rg: Registration section SR ... Switchback path 10 ... Control section 11: Upper limit determination section 12 ... Upper limit value storage section 13 ... Difference determination section 14 ... Dirt value storage section 15 ... Dirt position Determination unit 16 ... roller position information storage unit 17 ... device control unit 50 ... operation panel 100 ... ink jet printing apparatus 110 ... paper detection unit 130 ... ink jet head 320 ... side paper feed stand (paper feed stand)
330 ... paper feed tray (paper feed tray)
340 ... Paper discharge port 345 ... Paper discharge table 350 ... Registration roller (conveying means)
360 ... Conveying belt 370 ... Suction fan 380 ... Switching mechanism 390 ... Conveying roller (conveying means)

Claims (2)

A paper feeding means for feeding the medium placed on the paper feeding table to the circulation conveyance path;
Conveying means for conveying the medium supplied by the paper feeding means on the circulation conveying path;
Printing means for performing a printing process on the medium conveyed by the conveying means;
A paper discharge means for placing the medium subjected to the printing process by the printing means and discharged from the circulation conveyance path;
A stain detecting means provided on the circulation transport path for detecting the degree of dirt on the medium transported by the transport means;
Upper limit determination means for determining whether the degree of dirt detected by the dirt detection means exceeds a predetermined upper limit;
Difference determining means for determining whether or not the difference between the previous and current dirt levels detected by the dirt detecting means is smaller than a predetermined threshold;
When a cleaning process is required for the transporting unit, the medium is fed to the sheet feeding unit, and the medium is circulated and transported on the transporting unit without being subjected to a printing process by the printing unit. A control unit that executes the cleaning process of the medium by the medium that is circulated and conveyed,
A printing apparatus comprising:
When the cleaning process is started, the control unit
When the upper limit determination unit determines that the degree of contamination does not exceed a predetermined upper limit value, and the difference determination unit determines that the difference in contamination level is smaller than a predetermined threshold value, the upper limit determination unit conveys the circulating conveyance path. The medium to be discharged is discharged to the paper discharge means to finish the cleaning process,
When it is determined by the upper limit determination means that the degree of contamination does not exceed a predetermined upper limit value, and the difference determination unit determines that the difference in the degree of contamination is equal to or greater than a predetermined threshold value, Circulating the medium,
When the upper limit determination unit determines that the degree of contamination exceeds a predetermined upper limit value, the medium conveyed on the circulation conveyance path is discharged to the discharge unit and a new medium is discharged from the sheet supply unit. A printing apparatus, wherein the cleaning process is continued by supplying the circulating conveyance path. The control unit further includes:
When the difference determination unit continuously determines that the difference in the degree of contamination is smaller than a predetermined threshold value for a predetermined number of times, the medium conveyed through the circulation conveyance path is transferred to the sheet discharge unit. The printing apparatus according to claim 1, wherein the printing apparatus discharges paper.

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