JP2016022710A - Medium transportation mechanism, liquid discharge device and medium transportation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To satisfy both suppression of a paper jam at a place where a medium goes onto a platen surface and suppression of a reduction in transportation accuracy.SOLUTION: A transportation mechanism 30 of an ink jet printer 1 is provided with a release mechanism 37 releasing a nip state of a transportation roller 32a and a driven roller 32b. A transportation mechanism 30 can switch a transportation path feeding recording paper 11 to a platen surface 31a by release operation of the release mechanism 37 between a first transportation path 2A not having a step with respect to the platen surface 31a and a second transportation path 2B having a height from the platen surface 31a is greater than that of the first transportation path. At the time of release, the recording paper 11 is fed to the platen surface 31a via the second transportation path 2B by delivering force of a recording paper supply mechanism 10, and, subsequently, a state of a transportation roller pair 32 is switched to the nip state, the transportation roller 32a is driven and the recording paper 11 is transported via the first transportation path 2A.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a medium transport mechanism that feeds a sheet-shaped medium between a suction platen and a liquid discharge head, a medium transport method thereof, and a liquid discharge apparatus including the medium transport mechanism.

  In a liquid discharge apparatus such as an ink jet printer, a medium is fed onto a platen surface that supports a sheet-like medium, and liquid is discharged from a liquid discharge head onto a medium that is conveyed along the platen surface. A medium transport mechanism that transports a medium along the platen surface includes a pair of transport rollers that transport the medium with the medium sandwiched on the upstream side of the platen. In such a medium transport mechanism, conventionally, when a medium is fed from the nip portion of the transport roller pair to the platen surface, the medium floats from the platen surface by causing the medium to enter obliquely from above the platen surface. It is avoiding. Patent Document 1 discloses this type of liquid ejection device (inkjet printer).

JP 2010-201680 A

  When the medium is fed obliquely from above the platen surface as in Patent Document 1, a pair of transport rollers is disposed above the platen surface, and a medium transport path having a step between the transport roller and the platen surface is provided. Form. However, in such a medium conveyance path, the medium is bent in a curved shape when the medium fed obliquely from above is in a posture along the platen surface, and the degree of the bending changes depending on the strength of the medium and the crease. For example, the position of the step in the media transport path (conveying roller) when the stiffness of the part of the mount between the labels is weak or the media with creases such as fanfold paper is used. When a weak portion or fold passes through the boundary between the pair and the suction platen), the bending shape of the medium changes. Accordingly, the conveyance speed of the medium is disturbed, and the conveyance accuracy is lowered.

  In order to prevent such a disturbance in the conveyance accuracy, a medium conveyance path that does not cause the medium to bend, specifically, a medium conveyance path that is flat (straight) at the boundary between the conveyance roller pair and the suction platen. It is desirable to form. However, in such a medium transport path, when the medium enters the platen surface, the leading edge of the medium may be caught on the end of the suction platen, and paper jam may occur.

  SUMMARY OF THE INVENTION In view of the above-described problems, an object of the present invention is to provide a medium transport mechanism, a liquid discharge apparatus, and a medium transport method capable of achieving both suppression of paper jam at a portion where a medium enters the platen surface and suppression of decrease in transport accuracy. It is to propose.

  In order to solve the above-described problems, the medium transport mechanism of the present invention is directed toward the platen surface by the suction platen that sucks the sheet-like medium with the platen surface, and the first transport path having no step with the platen surface. From a pressing position that presses the medium against the other roller, a conveying roller that conveys the medium, a driven roller that sandwiches the medium between the conveying rollers, and one of the conveying roller and the driven roller. A release mechanism that moves to a release position away from the other roller, and a second conveyance path that is higher in height from the platen surface than the first conveyance path when the one roller moves to the release position. And a medium transport guide for guiding the medium so as to pass therethrough.

  In the present invention, as described above, a release mechanism that separates one of the transport roller and the driven roller from the other is provided, and when the medium is sandwiched between the transport roller and the driven roller, the first transport path has no step with the platen surface. When the medium is transported and the transport roller and the driven roller are in the release state, the medium is guided by the medium transport guide so that the height from the platen surface passes through the second transport path higher than the first transport path. In such a configuration, the medium is transported by either the first transport path having no step difference from the platen surface or the second transport path higher than the platen surface by the release operation of the roller pair (transport roller and driven roller) that transports the medium. It can be switched whether to carry. Therefore, when the conveyance accuracy is to be maintained, the medium is conveyed through the first conveyance path having no level difference from the platen surface, and a decrease in the conveyance accuracy due to the bending of the medium can be suppressed. Further, when there is a possibility that the medium is caught in the gap between the suction platen and the pair of transport rollers and the paper jam occurs, the medium can be transported by switching to the second transport path having a low risk of such a situation. Therefore, both paper jam suppression and reduction in conveyance accuracy can be achieved.

  The medium transport mechanism of the present invention further includes a medium supply mechanism that supplies the medium to the transport roller, and a control unit that controls operations of the medium supply mechanism, the transport roller, and the release mechanism, The control unit drives the medium supply mechanism with the one roller moved to the release position, and supplies the medium to a position higher than the platen surface in the second transport path; and It is preferable to perform a medium transport operation in which the transport roller is driven in a state where the one roller is moved to the pressing position, and the medium is transported along the platen surface in the first transport path. In this case, when the leading edge of the medium is fed to the platen surface (at the time of paper feeding), the medium is caught in the gap between the suction platen and the pair of conveyance rollers, and a paper jam is caused. Can be avoided. Further, when media processing such as printing is performed while transporting the medium, switching to the first transport path having no step is performed to suppress a decrease in transport accuracy, and a decrease in medium processing accuracy such as print accuracy can be suppressed.

  In the medium transport mechanism of the present invention, a first guide position that guides the medium at the same height as a nip position by the transport roller pair, and a height that is higher than the first guide position is higher than the first guide position. A guide moving mechanism that moves the medium conveyance guide to a second guide position, and the guide movement mechanism moves the medium conveyance guide to the second guide position when the one roller moves to the release position. The medium conveying guide may be moved to the first guide position when the one roller moves to the pressing position. In this way, when the medium is transported along the first transport path, the path from the medium transport guide to the transport roller pair can be made flat.

  In the medium transport mechanism of the present invention, it is preferable that the one roller is the driven roller and the other roller is the transport roller. If it does in this way, the conveyance roller which is a drive side roller, and the mechanism which rotates this can be installed in a fixed state. Therefore, a simple configuration can be achieved as compared with a structure in which a transport roller that is a driving roller is moved and released.

  Next, a liquid ejection apparatus according to the present invention includes the above-described medium transport mechanism, a liquid ejection head that can move to a printing position that faces the suction platen, and a retracted position that is retracted from above the suction platen. As described above, such a liquid ejecting apparatus can suppress the occurrence of a paper jam when the leading end of the medium is fed into the platen surface (at the time of paper feeding). Further, when printing is performed by ejecting liquid while transporting the medium, it is possible to suppress the decrease in the transport accuracy by switching to the first transport path having no step, thereby suppressing the decrease in the liquid discharge accuracy.

  Next, the medium conveying method of the present invention includes a first step of moving one of a conveying roller and a driven roller that conveys a sheet-shaped medium with a sheet-shaped medium interposed therebetween to a release position separated from the other roller, and a suction platen. The medium is guided by a medium conveyance guide so that the medium passes through a second conveyance path whose height from the platen surface is higher than the nip position of the medium by the conveyance roller and the driven roller, and the medium is guided above the platen surface. There is no step between the second step of feeding the medium, the third step of moving the one roller to a pressing position that presses the medium against the other roller, and the platen surface by driving the transport roller And a fourth step of transporting the medium along the platen surface in a first transport path. According to such a transport method, when the leading edge of the medium is fed to the platen surface (at the time of paper feeding), the first step and the second step are performed, the path through which the medium passes is switched to the second transport path, and the platen The medium can be fed to an upper position away from the surface. Accordingly, it is possible to avoid a paper jam due to the medium being caught in the gap between the suction platen and the conveying roller pair. In addition, when media processing such as printing is performed while feeding the medium after feeding, the third step and the fourth step are performed, and the path through which the medium passes is switched to the first transport path having no step to reduce the transport accuracy. Can be suppressed. Accordingly, it is possible to suppress a decrease in medium processing accuracy such as printing accuracy.

It is explanatory drawing which shows typically the principal part of the inkjet printer to which this invention is applied. It is a schematic block diagram which shows the control system of an inkjet printer. 6 is a flowchart of control for conveying a recording sheet by switching between a first conveyance path and a second conveyance path.

  Embodiments in which the present invention is applied to an inkjet printer, a recording paper transport mechanism, and a recording paper transport method will be described below with reference to the drawings.

  FIG. 1A and FIG. 1B are explanatory views schematically showing main parts of an ink jet printer to which the present invention is applied, and FIG. 1A is conveying a recording sheet through a first conveyance path. FIG. 1B shows a state where the recording paper is being conveyed through the second conveyance path. Hereinafter, in this specification, the three directions of the printer longitudinal direction Y, the printer vertical direction Z, and the printer width direction (not shown) are orthogonal to each other. Also, one side of the printer longitudinal direction Y is the printer front Y1, the other side is the printer rear Y2, one side of the printer vertical direction Z is the printer upper Z1, and the other side is the printer lower Z2.

  The ink jet printer 1 (liquid ejection device) includes a recording paper supply mechanism 10 (medium supply mechanism), a tension mechanism 20, a transport mechanism 30, a printing mechanism 40, and the like. The recording paper supply mechanism 10, the tension mechanism 20, and the conveyance mechanism 30 constitute a recording paper conveyance mechanism (medium conveyance mechanism) to which the present invention is applied. As shown in FIGS. 1A and 1B, the recording paper supply mechanism 10 is disposed at the lower part of the ink jet printer 1, and the tension mechanism 20 is disposed obliquely above the rear Y2 side of the printer. The recording paper supply mechanism 10 includes a roll paper drive shaft 13 for mounting a roll paper 12 obtained by winding a long recording paper 11 (medium) in a roll shape, and a roll paper drive motor 14 for rotating the roll paper drive shaft 13 (see FIG. 2). When the roll paper drive shaft 13 rotates, the recording paper 11 is fed obliquely upward toward the tension mechanism 20 from the roll paper 12 that is non-rotatably mounted on the roll paper drive shaft 13.

  The tension mechanism 20 includes a tension lever 21, a tension roller 22 provided at the tip of the tension lever 21, and a biasing member (not shown) such as a spring that biases the tension lever 21 toward the printer rear Y2. The recording paper 11 drawn obliquely upward from the roll paper 12 is hung on the tension roller 22 and drawn to the front Y1 side of the printer and supplied to the transport mechanism 30. The recording paper 11 is conveyed in a state where a predetermined tension is applied by the urging force of the tension mechanism 20. Further, the load fluctuation when the recording paper 11 is conveyed is reduced by the swinging of the tension lever 21. Accordingly, the tension mechanism 20 suppresses a decrease in the conveyance accuracy of the recording paper 11 due to a variation in the conveyance load.

  The transport mechanism 30 includes a suction platen 31 having a substantially horizontal platen surface 31 a facing the printer upper side Z <b> 1, a transport roller pair 32 disposed on the printer rear Y <b> 2 side of the suction platen 31, and the suction platen 31 on the printer front Y <b> 1 side. A pair of discharged paper rollers 33, a recording paper transport guide 34 (medium transport guide) disposed between the tension lever 21 and the transport roller pair 32, and a transport roller 32a that is a driving roller of the transport roller pair 32. 2, a pressing mechanism 36 that presses the driven roller 32 b of the transport roller pair 32 against the transport roller 32 a, and a release mechanism 37 that separates the driven roller 32 b from the transport roller 32 a.

  A number of suction holes are formed in the platen surface 31 a of the suction platen 31. The suction platen 31 includes a suction space communicating with the suction hole of the platen surface 31a, a suction pump 31b (see FIG. 2) that forms a negative pressure in the suction space, and the like. When the suction pump 31b is driven, the recording paper 11 passing over the platen surface 31a is sucked to the platen surface 31a. This prevents the recording paper 11 from being lifted from the platen surface 31a when the recording paper 11 is fed onto the platen surface 31a.

  The recording paper 11 supplied to the transport mechanism 30 via the tension mechanism 20 is guided by a recording paper guide surface 34 a that is the upper end surface of the recording paper transport guide 34, and is driven by a transport roller 32 a constituting the transport roller pair 32. It passes between the rollers 32b and is fed onto the platen surface 31a. The recording paper 11 transported along the platen surface 31a by the transport force of the transport roller pair 32 passes between the paper discharge roller 33a and the driven roller 33b constituting the paper discharge roller pair 33 and is further sent to the front Y1 side of the printer. It is.

  The conveyance roller 32a is disposed at a position where the recording paper 11 is conveyed at the same height as the platen surface 31a. Further, the driven roller 32b is disposed on the upper Z1 side of the printer with respect to the transport roller 32a. The driven roller 32b is supported by a roller support lever 38 so as to be movable in the vertical direction Z of the printer. The pressing mechanism 36 includes an urging member such as a spring that urges the roller support lever 38 toward the lower Z2 side of the printer, and the urging force moves the driven roller 32b at the pressing position A1 that presses the recording paper 11 against the conveyance roller 32a. (See FIG. 1A). Thereby, a nip state of the recording paper 11 by the conveying roller pair 32 is formed.

  The transport mechanism 30 drives the transport motor 35 to rotate the transport roller 32a in a state where the recording paper 11 is pressed against the transport roller 32a by the pressing mechanism 36, and transports the recording paper 11 to the front Y1 side of the printer. At this time, the recording paper 11 is fed from the conveyance roller pair 32 to the platen surface 31a through a straight first conveyance path 2A as shown in FIG. The first transport path 2A is a path that is not stepped from the platen surface 31a. More specifically, the height of the nip position of the recording paper 11 by the transport roller pair 32 (position in the printer vertical direction Z) is the platen surface 31a. The path is set to be the same as the height of the adsorbed recording paper 11.

  The release mechanism 37 includes a release motor 37a (see FIG. 2) and a power transmission mechanism (not shown) that swings the roller support lever 38 in the direction opposite to the urging direction of the pressing mechanism 36 based on the output rotation of the release motor 37a. ). For example, a swing shaft that swings integrally with the roller support lever 38 is provided, and the rotation of the release motor 37a is decelerated and transmitted to the swing shaft to swing the roller support lever 38. The release mechanism 37 moves the driven roller 32b from the pressing position A1 shown in FIG. 1A to the release position A2 shown in FIG.

  When the conveyance roller pair 32 is released by the release mechanism 37, the recording paper 11 supplied from the recording paper supply mechanism 10 is conveyed at a height determined by the recording paper guide surface 34 a of the recording paper conveyance guide 34. The recording paper transport guide 34 is a paper guide member having a substantially horizontal recording paper guide surface 34a formed on the upper end thereof. As shown in FIG. 1B, the second transport path 2B is higher in height from the platen surface 31a than the first transport path 2A, and is sent to a position away from the platen surface 31a toward the printer upper Z1 side.

  That is, in this example, the transport roller 32a and the platen surface 31a are arranged to transport the recording paper 11 at the same height, whereas the recording paper guide surface 34a of the recording paper transport guide 34 is a platen surface. It is located on the upper Z1 side of the printer with respect to 31a. Accordingly, when the recording paper 11 is supplied from the recording paper supply mechanism 10 to the conveyance mechanism 30 with the conveyance roller pair 32 being in the release state, the recording paper 11 supported by the recording paper guide surface 34a is positioned higher than the recording paper guide surface 34a. Now, it passes through the position above the printer Z1 side with respect to the transport roller 32a. Accordingly, the recording paper 11 is fed above the platen surface 31a in the second conveyance path 2B higher than the first conveyance path 2A.

  The printing mechanism 40 includes an inkjet head 41 (liquid ejection head) that ejects ink onto the recording paper 11 conveyed along the platen surface 31a of the suction platen 31, and an inkjet head 41 that reciprocates in the printer width direction (not shown). And a head moving mechanism 42 to be moved. The head moving mechanism 42 includes, for example, a carriage 42a on which the inkjet head 41 is mounted, a carriage guide shaft 42b extending in the printer width direction, and a belt mechanism (not shown) that moves the carriage 42a along the carriage guide shaft 42b. And a carriage motor 42c (see FIG. 2) for driving the belt mechanism. The head moving mechanism 42 performs ink jetting between a printing position 41A (see FIG. 1A) facing the platen surface 31a from above the printer Z1 and a retracted position (not shown) retracted from the platen surface 31a. The head 41 is moved. FIG. 1B shows a state in which the inkjet head 41 has been retracted from above the platen surface 31a.

(Control system)
FIG. 2 is a schematic block diagram illustrating a control system of the ink jet printer 1. The ink jet printer 1 includes a control unit 50 that controls the recording paper supply mechanism 10, the transport mechanism 30, the printing mechanism 40, and the like based on print data and control signals supplied from a host device. The control unit 50 includes a communication unit 51 that inputs / outputs print data and control signals to / from a host device. In addition, the control unit 50 receives an output of a sensor or the like provided in each unit of the inkjet printer 1. On the other hand, the roll paper drive motor 14, the suction pump 31b, the transport motor 35, the release motor 37a, the carriage motor 42c, and the like are connected to the output side of the control unit 50.

  The control unit 50 drives the roll paper drive motor 14 to perform a feeding operation for feeding the recording paper 11 from the roll paper 12 toward the tension lever 21. Further, in conjunction with this feeding operation, the release motor 37a and the transport motor 35 of the transport mechanism 30 are driven to switch between the first transport path 2A and the second transport path 2B, and recording is performed on the second transport path 2B. A recording paper supply operation for supplying the paper 11 and a recording paper transport operation for transporting the recording paper 11 through the first transport path 2A are performed.

  Further, when transporting the recording paper 11 through the first transport path 2A, the control unit 50 drives the suction pump 31b of the suction platen 31 to transport the recording paper 11 while sucking the recording paper 11 onto the platen surface 31a. . Further, the control unit 50 determines the transport position of the recording paper 11 based on the driving amount of the sensor and the transport motor 35. When the print area of the recording paper 11 passes below the ink jet head 41, ink is ejected from the ink jet head 41 in conjunction with the recording paper transport operation by the transport motor 35, and printing on the recording paper 11 is performed. .

(Control for transporting the recording paper 11 by switching the first and second transport paths 2A and 2B)
FIG. 3 is a flowchart of control for conveying the recording paper 11 by switching between the first conveyance path 2A and the second conveyance path 2B. The controller 50 starts this control before the recording paper 11 fed from the roll paper 12 loaded in the recording paper supply mechanism 10 reaches the platen surface 31a. Further, when starting this control, the control unit 50 keeps the inkjet head 41 retracted from the platen surface 31a.

  First, the control unit 50 performs the release operation of the transport roller pair 32 by the release mechanism 37 (step S1). Specifically, the release motor 37a is driven to swing the roller support lever 38, and the driven roller 32b is retracted to the release position A2 of the printer upper Z1. As a result, the transport path of the recording paper 11 is switched to the second transport path 2B for transporting the recording paper 11 at a height guided by the recording paper guide surface 34a of the recording paper transport guide 34.

  Next, the controller 50 maintains the release roller pair 32 in the release state, and performs a recording paper supply operation for feeding the recording paper 11 onto the platen surface 31a through the second conveyance path 2B (step S2). Specifically, the roll paper drive motor 14 is driven to rotate the roll paper drive shaft 13 and the roll paper 12, and the recording paper 11 is fed out. The fed recording paper 11 is sent to the transport mechanism 30 by the feeding force of the roll paper drive motor 14, and is transported to the printer front Y1 along the recording paper guide surface 34a. Then, the recording paper 11 is sent to an upper position away from the platen surface 31a through the second conveyance path 2B passing above the conveyance roller 32a.

  Subsequently, the control unit 50 performs an operation of returning the transport roller pair 32 to the nip state (step S3). Specifically, the release motor 37a is driven in the opposite direction to that at the time of release, the driven roller 32b is moved to the pressing position A1 of the printer lower Z2, and the recording paper 11 is pressed against the conveying roller 32a. As a result, the transport path of the recording paper 11 is lowered from the height of the recording paper guide surface 34a to the height of the transport roller 32a, and the first transport path 2A that transports the recording paper 11 at the height of the transport roller 32a. Can be switched.

  After returning the conveyance roller pair 32 to the nip state, the controller 50 drives the carriage motor 42c to move the inkjet head 41 to the printing position 41A, and the distance (platen gap) between the inkjet head 41 and the platen surface 31a. The inkjet head 41 is positioned so that becomes a predetermined dimension (step S4). Further, the suction pump 31 b is driven to suck the recording paper 11 by the suction platen 31. Thereafter, the roll paper drive motor 14 and the transport motor 35 are driven in conjunction with each other, and the recording paper 11 is transported by the transport force of the transport roller pair 32 while the recording paper 11 is fed by the feed force of the roll paper drive motor 14. A paper transport operation is performed (step S5). As described above, ink is ejected from the inkjet head 41 in accordance with the transport position of the recording paper 11 while performing the recording paper transport operation, and printing on the recording paper 11 is performed.

(Function and effect)
As described above, the ink jet printer 1 of the present example includes the release mechanism 37 that releases the nip state between the conveyance roller 32a and the driven roller 32b, and the recording paper 11 is moved to the platen surface 31a by the release operation of the release mechanism 37. Can be switched to the first transport path 2A having no level difference from the platen surface 31a and the second transport path 2B having a height from the platen surface 31a higher than that of the first transport path 2A. Therefore, when the conveyance accuracy is to be maintained, the recording paper 11 is conveyed through the first conveyance path 2 </ b> A having no step with the platen surface 31 a, and a decrease in the conveyance accuracy due to the bending of the recording paper 11 can be suppressed. Further, when there is a possibility that the recording paper 11 is caught in the gap between the suction platen 31 and the conveyance roller pair 32 and the paper is jammed, the recording paper 11 is switched to the second conveyance path 2B which has a low possibility of such a situation. Can be transported. Therefore, both paper jam suppression and reduction in conveyance accuracy can be achieved.

  Specifically, in this example, the recording paper supply mechanism 10 that supplies the recording paper 11 to the conveyance mechanism 30 is provided, and the control unit 50 of the ink jet printer 1 sets the conveyance roller pair 32 to the release state and records the recording paper. By driving the supply mechanism 10, a recording paper supply operation for feeding the recording paper 11 to a position higher than the platen surface 31a in the second transport path 2B is performed. Further, by driving the transport roller 32a with the transport roller pair 32 in a nip state, a recording paper transport operation for transporting the recording paper 11 along the platen surface 31a is performed in the first transport path 2A. As described above, by feeding the leading end of the recording paper 11 above the platen surface 31a through the second transport path 2B during paper feeding, the recording paper is inserted into the gap between the end of the suction platen 31 on the Y2 side behind the printer and the transport roller 32a. There is a low possibility that paper jam will occur due to the tip of 11 being caught. At this time, since the inkjet head 41 is retracted from above the platen surface 31a, even if the recording paper 11 is sent through the second transport path 2B, the leading edge of the recording paper 11 collides with the inkjet head 41 and a paper jam occurs. I will not let you. On the other hand, after feeding, the recording paper 11 can be transported by the transport roller 32a with high transport accuracy on the first transport path 2A having no step with the platen surface 31a. Accordingly, it is possible to achieve both suppression of paper jam at the time of paper feeding and suppression of lowering of conveyance accuracy at the time of printing, and it is possible to ensure printing accuracy while suppressing paper jam.

(Modification)
(1) In the above embodiment, the recording paper supply mechanism 10 is configured to feed the recording paper 11 by rotating the roll paper 12 that is mounted on the roll paper drive shaft 13 so as not to be relatively rotatable. Instead, a feeding roller is disposed between the shaft on which the roll paper 12 is mounted and the tension mechanism 20, and the recording paper 11 pulled out from the roll paper is brought into contact with the feeding roller, and the recording paper 11 is fed out by rotation of the feeding roller. You may comprise. Alternatively, the recording paper 11 may be fed out from the roll paper 12 stored in a rollable state in the roll paper storage unit without providing a shaft for mounting the roll paper 12.

(2) In the above embodiment, the paper guide member disposed between the tension mechanism 20 and the pair of transport rollers 32 is used as the recording paper transport guide 34. However, instead of such a paper guide member, the tension mechanism 20 is used. This member may also be used as a recording paper conveyance guide for guiding the recording paper 11 so as to pass through the second conveyance path 2B. For example, when the tension mechanism 20 is configured not to swing the tension roller 22 in the vertical direction Z of the printer with the tension lever 21 but to move the tension roller 22 in the longitudinal direction Y of the printer, It can also be used as a recording paper conveyance guide. Alternatively, when the tension mechanism 20 is omitted, a feeding roller disposed between the roll paper 12 and the transport mechanism 30 may be used as a recording paper transport guide. In these configurations, the tension roller 22 and the feeding roller are arranged at a position higher than the platen surface 31a, so that recording is performed so as to pass through the second transport path 2B that is farther from the platen surface 31a than the first transport path 2A. It is possible to guide the paper 11.

(3) In the above embodiment, when releasing the transport roller pair 32, the transport roller 32a is not moved and the driven roller 32b is retracted to the upper Z1 of the printer. However, the transport roller 32a and the driven roller 32b are arranged upside down. Thus, the release may be performed by retracting the transport roller 32a to the upper Z1 of the printer.

(4) The driven roller 32b is retracted to the upper Z1 of the printer to perform the release in the same manner as in the above embodiment. At the time of release, the conveyance roller 32a may be raised to the same height as the recording paper conveyance guide 34. If it does in this way, when conveying by the 2nd conveyance path 2B, the recording paper 11 can be supported by the conveyance roller 32a. In this case, the recording paper conveyance guide 34 can be omitted.

(5) In the above embodiment, the recording paper transport guide 34 is fixed at a position where the recording paper guide surface 34a is at the same height as the second transport path 2B, but the recording paper transport guide 34 is moved in the vertical direction Z of the printer. The recording paper conveyance guide 34 may be configured to move to the lower Z2 of the printer at a timing when the conveyance path of the recording paper 11 is switched to the first conveyance path 2A by a release operation. The guide moving mechanism for moving the recording paper transport guide 34 can be configured to move the recording paper transport guide 34 in synchronization with the release operation, for example, using the release motor 37a of the release mechanism 37 as a drive source. .

  That is, the guide moving mechanism moves the recording paper conveyance guide 34 to the first guide position for guiding the recording paper 11 at the same height as the nip position by the conveyance roller pair 32 when the driven roller 32b moves to the pressing position A1. Let Further, the guide moving mechanism is configured such that when the driven roller 32b moves to the release position A2, the second guide position (for example, FIG. 1B of the above-described form in FIG. 1B) is higher than the first guide position. The recording paper transport guide 34 is moved to (position). In this way, when the recording paper 11 is transported along the first transport path 2A, it is possible to avoid the recording paper 11 from being greatly bent between the recording paper transport guide 34 and the transport roller pair 32. .

(6) In the above embodiment, the roll paper is loaded and printed on the recording paper 11 fed out of the roll paper. However, the present invention is applied to an ink jet printer that loads fanfold paper and supplies it to the transport mechanism 30. Is also applicable.

(Other forms)
In the above embodiment, the present invention is applied to the ink jet printer 1 that prints by ejecting ink onto the recording paper 11 with the ink jet head 41. However, the present invention ejects liquid other than ink onto a sheet-like medium. The present invention can be applied to various liquid ejection devices.

DESCRIPTION OF SYMBOLS 1 ... Inkjet printer (liquid discharge apparatus), 2A ... 1st conveyance path, 2B ... 2nd conveyance path, 10 ... Recording paper supply mechanism (medium supply mechanism), 11 ... Recording paper, 12 ... Roll paper, 13 ... Roll paper Drive shaft, 14 ... roll paper drive motor, 20 ... tension mechanism, 21 ... tension lever, 22 ... tension roller, 30 ... recording paper transport mechanism, 31 ... suction platen, 31a ... platen surface, 31b ... suction pump, 32 ... transport Roller pair, 32a ... conveying roller (the other roller), 32b ... driven roller (one roller), 33 ... discharge roller pair, 33a ... discharge roller, 33b ... driven roller, 34 ... recording paper transport guide (medium transport) Guide), 34a ... Recording paper guide surface, 35 ... Conveyance motor, 36 ... Pressing mechanism, 37 ... Release mechanism, 37a ... Release motor 38, roller support lever, 40 ... printing mechanism, 41 ... inkjet head, 41A ... printing position, 42 ... head moving mechanism, 42a ... carriage, 42b ... carriage guide shaft, 42c ... carriage motor, 50 ... control unit, 51 ... Communication section, A1 ... Pressing position, A2 ... Release position, Y ... Front / rear direction of printer, Y1 ... Front of printer, Y2 ... Back of printer, Z ... Up / down direction of printer, Z1 ... Upper side of printer, Z2 ... Lower side of printer

Claims (6)

A suction platen for sucking a sheet-like medium on the platen surface;
A transport roller for transporting the medium toward the platen surface in a first transport path having no step with the platen surface;
A driven roller that sandwiches the medium between the conveying rollers;
A release mechanism for moving one of the transport roller and the driven roller from a pressing position for pressing the medium against the other roller to a release position separated from the other roller;
A medium conveyance guide that guides the medium so that when the one roller moves to the release position, the medium passes through a second conveyance path whose height from the platen surface is higher than the first conveyance path. A medium transport mechanism characterized by the above. further,
A medium supply mechanism for supplying the medium to the transport roller;
A control unit that controls operations of the medium supply mechanism, the transport roller, and the release mechanism,
The controller is
A medium supply operation of driving the medium supply mechanism in a state where the one roller is moved to the release position, and feeding the medium to a position higher than the platen surface in the second transport path;
A medium conveying operation of driving the conveying roller in a state where the one roller is moved to the pressing position and conveying the medium along the platen surface in the first conveying path. The medium transport mechanism according to claim 1. further,
The medium transport guide is moved to a first guide position for guiding the medium at the same height as a nip position by the transport roller pair, and to a second guide position whose height from the platen surface is higher than the first guide position. A guide moving mechanism
The guide moving mechanism is
When the one roller moves to the release position, the medium transport guide is moved to the second guide position,
3. The medium conveyance mechanism according to claim 1, wherein when the one roller moves to the pressing position, the medium conveyance guide is moved to the first guide position. 4. The one roller is the driven roller;
The medium transport mechanism according to claim 1, wherein the other roller is the transport roller. The medium transport mechanism according to any one of claims 1 to 4,
A liquid discharge apparatus comprising: a printing position facing the suction platen; and a liquid discharge head movable to a retreat position retracted from above the suction platen. A first step of moving one of a transport roller and a driven roller for transporting the sheet-like medium in a release position away from the other roller;
The medium is guided by the medium transport guide so that the suction platen passes through the second transport path in which the height from the platen surface of the suction platen is higher than the nip position of the medium by the transport roller and the driven roller, and above the platen surface. A second step of feeding the medium into
A third step of moving the one roller to a pressing position for pressing the medium against the other roller;
And a fourth step of transporting the medium along the platen surface in a first transport path having no step between the transport roller and the platen surface. .

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