Patent Description:
A large format inkjet printer may perform printing on sheets of different sheet lengths. For example, in a printer that performs printing on a roll sheet, it is possible to change the sheet length of a discharged sheet by changing the cutting position of the roll sheet. Further, there has been proposed a printer including a plurality of discharge paths having different path lengths, in which the discharge path can be selectively switched (for example, <CIT>). In this printer, in accordance with switching of the discharge path, separation between a pair of rollers which nip and convey a sheet is switched.

Accordingly, if the discharge path is not switched, the number of pairs of rollers which simultaneously nip the sheet changes depending on the sheet length. This causes scratches on the sheet or a decrease in conveyance accuracy. Thus, when conveying sheets of different sheet lengths, various problems occur. Therefore, it is necessary to appropriately configure the pair of rollers, the separation mechanism for the pair of rollers, the switching mechanism for the discharge paths, and the conveyance mechanism including the conveyance path in accordance with the problems. <CIT> relates to a sheet carrying device in which a skew of a sheet carried along a passage is corrected relative to a carrying direction. <CIT> relates to a printing apparatus with a common driving source configured to apply a driving force to a first roller pair and a second roller pair, and a clutch mechanism configured to cut power from the driving source to the second roller pair.

The present invention provides a printing apparatus that can appropriately convey sheets of different sheet lengths.

The present invention provides a printing apparatus as specified in claims <NUM> to <NUM>.

<FIG> is an external perspective view of a printing apparatus <NUM> according to an embodiment of the present invention, and <FIG> is a schematic view showing the internal structure of the printing apparatus <NUM>. An arrow X indicates the widthwise direction (left-and-right direction) of the printing apparatus <NUM>, an arrow Y indicates the depth direction (front-and-rear direction) of the printing apparatus <NUM>, and an arrow Z indicates the vertical direction. Note that "printing" includes not only forming significant information such as characters and graphics but also forming images, figures, patterns, and the like on print media in a broad sense, or processing print media, regardless of whether the information formed is significant or insignificant or whether the information formed is visualized so that a human can visually perceive it. In addition, although in this embodiment, sheet-like paper is assumed as a "print medium" serving as a print target, sheet-like cloth, a plastic film, and the like may be used as print media.

An operation panel 1a for accepting user's instruction is provided in the front portion of the printing apparatus <NUM>. A user can use various kinds of switches and the like provided in the operation panel 1a to input various kinds of commands such as a designation of the sheet size and setting of the discharge destination of a printed sheet.

In the lower portion of the printing apparatus <NUM>, a plurality of feeding units <NUM> are vertically arranged in a plurality of stages (two stages in this example). Each feeding unit <NUM> forms a storage section that stores a roll sheet R as a print medium. Each feeding unit <NUM> includes support portions that support the roll sheet R so as to be rotatable around the X-direction axis, and also includes a feeding mechanism that pulls out a sheet from the roll sheet R and feeds it to a conveyance path RT. In this embodiment, the widthwise direction of the sheet is the X direction. The user can perform a replacement operation of the roll sheet R from the front of the printing apparatus <NUM>. Note that in this embodiment, the roll sheet R is exemplified as the print medium, but the print medium may be a cut sheet.

The conveyance path RT is a sheet path defined by a guide structure which guides a sheet, and extends from the feeding unit <NUM> to a discharge port <NUM> or a discharge port <NUM> while curving in the midway. In the following description, an upstream side and a downstream side are the upstream side and the downstream side with respect to the sheet conveyance direction, respectively.

The sheet pulled out from the roll sheet R is supplied via a conveyance unit <NUM> to a position facing a printhead <NUM>. The conveyance unit <NUM> includes a conveying roller 3a, which is a driving rotating body, and a nip roller 3b, which is a driven rotating body pressed against the conveying roller 3a. While being nipped by the conveying roller 3a and the nip roller 3b, the sheet is conveyed on the conveyance path RT in the arrow direction by rotation of the rollers.

The printhead <NUM> is arranged on the downstream side of the conveyance unit <NUM>. The printhead <NUM> in this embodiment is an inkjet head which prints an image on a sheet by discharging ink. The printhead <NUM> uses a discharge energy generating device such as an electrothermal transducer (heater) or a piezoelectric device to discharge ink from the discharge port. The printing apparatus <NUM> according to this embodiment is a serial scanning inkjet printing apparatus, and the printhead <NUM> is mounted on a carriage <NUM>. The carriage <NUM> is configured to be reciprocated in the X direction (the widthwise direction of the sheet) by a driving mechanism (not shown). In the vicinity of the printhead <NUM>, the sheet is conveyed in the Y direction. By alternately repeating intermittent conveyance of the sheet by the conveyance unit <NUM> and an operation including moving the carriage <NUM> and ink discharge by the printhead <NUM>, an image is printed on the sheet.

Note that the serial scanning printing apparatus is exemplarily shown in this embodiment, but the present invention is also applicable to a full-line printing apparatus. In this case, a long printhead extending in the widthwise direction of a sheet is used as the printhead <NUM>. Then, by discharging ink from the printhead while continuously conveying the sheet, an image is printed on the sheet. Further, although the inkjet printing apparatus is exemplarily shown in this embodiment, the present invention is also applicable to printing apparatuses of other printing types.

A cutting unit <NUM> is arranged on the downstream side of the printhead <NUM>. The cutting unit <NUM> cuts the sheet, which has been pulled out from the roll sheet R and has an image printed thereon, in the widthwise direction of the sheet. With this, the sheet pulled out from the roll sheet R is cut by the cutting unit <NUM> and becomes a cut sheet. A sheet guide structure adjacent to the cutting unit <NUM> includes a movable support member <NUM>. The movable support member <NUM> is one of guide members which forms the conveyance path RT while supporting the sheet from below. The movable support member <NUM> is configured to be moved at the time of a cutting operation of the cutting unit <NUM>. The details will be described later.

A discharge unit <NUM> is arranged on the downstream side of the cutting unit <NUM>. The discharge unit <NUM> is one of conveyance units for conveying the sheet. The discharge unit <NUM> is a unit for discharging the sheet having undergone printing. The discharge unit <NUM> includes a discharge roller 7a, which is a driving rotating body, and a nip roller 7b, which is a driven rotating body pressed against the discharge roller 7a. While being nipped by the discharge roller 7a and the nip roller 7b, the sheet is conveyed on the conveyance path RT in the arrow direction by rotation of the rollers. In this embodiment, the discharge unit <NUM> is configured to be switchable between a nip state (a nip state between the rollers) for nipping the sheet and a nip released state (a nip released state between the rollers). The details will be described later.

The conveyance path RT branches at a branch point BR on the downstream side of the discharge unit <NUM>, and includes a plurality of discharge paths including a discharge path RT1 and a discharge path RT2. The discharge path RT1 is a sheet discharge path extending from the branch point BR to the discharge port <NUM>, and a path for discharging the sheet to the rear side in the Y direction. The discharge path RT2 is a sheet discharge path extending from the branch point BR to the discharge port <NUM>, and a path for discharging the sheet to the front side in the Y direction. In this embodiment, the path length of the discharge path RT1 is longer than that of the discharge path RT2, and the discharge path RT1 extends in the Y direction in the upper portion of the printing apparatus <NUM>.

The branch point BR is a path switching position where a path switching member <NUM> is arranged. The path switching member <NUM> includes a shaft 14a extending in the X direction, and is provided so as to be pivotable with the shaft 14a as the pivot center. The path switching member <NUM> switches, between the plurality of discharge paths RT1 and RT2, the discharge path used to discharge a sheet having undergone printing by the printhead <NUM>. Switching of the discharge paths is performed in accordance with, for example, user's selection instruction. The position of the path switching member <NUM> shown in <FIG> is the position for selecting the discharge path RT1.

The discharge port <NUM> is located in the rear portion of the printing apparatus <NUM>, and open in the back face of the printing apparatus <NUM>. A plurality of guides 9b that restrict a warp of the sheet is provided in the upper portion of the discharge port <NUM>. The discharge path RT1 passes above the shaft 14a, and a reversing section <NUM>, a discharge unit <NUM>, and a stacking section <NUM> are provided midway along the discharge path RT1 from the upstream side toward the downstream side.

The reversing section <NUM> is a structure for reversing the sheet having undergone printing. In this embodiment, by forming, midway along the discharge path RT1, a curved portion (in this embodiment, a U shape (an inverted C shape in the side view shown in <FIG>)) where the shape of the path is curved, the sheet is reversed. At the time of having passed through the printhead <NUM>, the upper surface of the sheet is the image printed surface, but the image printed surface of the sheet becomes the lower surface after passing through the reversing section <NUM>. The reversing section <NUM> includes a guide member <NUM>, which forms a U-shaped outer path forming wall (guide surface), and a guide member <NUM>, which forms the inner path forming wall (guide surface), and the path is formed between the guide members <NUM> and <NUM>.

The discharge unit <NUM> is one of the conveyance units for conveying the sheet. The discharge unit <NUM> is a unit for discharging the sheet having undergone printing. The discharge unit <NUM> includes a discharge roller 8a, which is a driving rotating body, and a nip roller 8b, which is a driven rotating body pressed against the discharge roller 8a. While being nipped by the discharge roller 8a and the nip roller 8b, the sheet is conveyed by rotation of the rollers. The stacking section <NUM> is arranged on the downstream side of the discharge unit <NUM>, and the discharge unit <NUM> conveys, to the stacking section <NUM>, the sheet with the image printed thereon by the printhead <NUM>. In this embodiment, the discharge unit <NUM> cannot be switched between a nip state and a nip released state like the discharge unit <NUM>, and it is always in the nip state.

The stacking section <NUM> forms a tray which receives a plurality of sheets discharged from the discharge unit <NUM>, and the stacking section <NUM> is arranged inside the printing apparatus <NUM>. The stacking section <NUM> forms the discharge path RT1 which is almost horizontal in the rear portion in the Y direction and slopes upward toward the rear portion in the front portion in the Y direction. Depending on the length of the sheet, the end portion of the sheet may come out of the discharge port <NUM>. The stacking section <NUM> forms a part of the discharge path RT1.

A window portion 9a for exposing the stacking section <NUM> is formed in the top portion of the printing apparatus <NUM>, so that the user can visually recognize the stacking amount of sheets on the stacking section <NUM> via the window portion 9a. A plurality of guide members 9c are disposed in the window portion 9a to prevent the sheet discharged onto the stacking section <NUM> from being discharged from the window portion 9a.

The discharge port <NUM> is located in the front portion of the printing apparatus <NUM> and open to the front of the printing apparatus <NUM>. The discharge path RT2 is a path passing below the shaft 14a, and does not have a structure for reversing the sheet like the reversing section <NUM>. That is, the image printed surface of the sheet discharged from the discharge port <NUM> is the upper surface. Further, no sheet conveyance mechanism like the discharge unit <NUM> is provided midway along the discharge path RT2. Accordingly, the sheet is conveyed by conveyance of the conveyance unit <NUM>, cut by the cutting unit <NUM>, and discharged from the discharge port <NUM> due to its own weight or by a manual operation of the user.

As has been described above, in this embodiment, it is possible to select whether to discharge the sheet to the stacking section <NUM> on the upper side or to the front of the printing apparatus <NUM>. For example, if the number of discharged sheets is large, the stacking section <NUM> may be selected, and if the sheet length is long, discharge from the discharge port <NUM> may be selected. In this manner, it is possible for the user to arbitrarily select the discharge path.

<FIG> shows an example of the operation mode of the printing apparatus <NUM>. In the example shown in <FIG>, a printed sheet S has been discharged onto the stacking section <NUM>. The position of the path switching member <NUM> in <FIG> is the position for selecting the discharge path RT2. If the discharge path RT2 is selected, the printed sheet S is discharged from the discharge port <NUM> to the front of the printing apparatus <NUM> in the mode shown in <FIG>. At this time, the discharged sheet S is collected by a basket <NUM> as exemplarily shown in <FIG>. The basket <NUM> may be a member different from the printing apparatus <NUM>, or may be provided in the lower portion of the printing apparatus <NUM> so as to be retractable.

<FIG> is a block diagram of a control unit <NUM> of the printing apparatus <NUM>. The control unit <NUM> includes a processing unit 18a which is a processor such as a CPU, a storage unit 18b which is a storage device such as a ROM or a RAM, and an interface unit 18c which relays signals from/to external devices. The processing unit 18a executes programs stored in the storage unit 18b and, for example, controls an actuator group 19A based on setting information accepted using the operation panel 1a or a detection result of a sensor group 19B. As the setting information, the kind and width of the sheet S, selection information of the discharge path, and the like are included. The actuator group 19A includes the driving source (for example, motor) of each of the feeding unit <NUM> and the conveyance unit <NUM>, motors M1 to M3 to be described later, an electromagnetic clutch provided in a gear <NUM> to be described later, and the like. The sensor group 19B includes, in addition to sensors <NUM> and <NUM> to be described later, a plurality of sheet detection sensors for detecting the leading end position and the trailing end position of the sheet S in the conveyance path RT, and the like.

The components in vicinity of the reversing section <NUM> and driving systems for driving them will be described. <FIG> is a sectional view showing the vicinity of the reversing section <NUM>. From the upstream side on the conveyance path RT, the cutting unit <NUM>, the movable support member <NUM>, the discharge unit <NUM>, the path switching member <NUM>, and the discharge unit <NUM> are arranged. The discharge unit <NUM> is arranged at a position higher than the discharge unit <NUM>, and the path (the U-shaped portion of the discharge path RT1) of the reversing section <NUM> is arranged between the discharge unit <NUM> and the discharge unit <NUM>. Further, an elevating mechanism <NUM> which vertically moves the nip roller 7b is arranged in a space between the discharge unit <NUM> and the discharge unit <NUM> in the Z direction.

In this embodiment, the movable support member <NUM> and the elevating mechanism <NUM> are driven by a driving unit (DU1), and the discharge rollers 7a and 8a and the path switching member <NUM> are driven by a driving unit (DU2). The arrangement of each driving unit will be described below.

<FIG> is a schematic view of the driving unit DU1. The driving unit DU1 forms a moving mechanism that moves the movable support member <NUM> to a support position for supporting a sheet and a retreat position retreated from the support position. The driving unit DU1 also forms a state switching mechanism that switches the nip state and the nip released state of the discharge unit <NUM>. In order to switch the nip state and the nip released state, the state switching mechanism causes the elevating mechanism <NUM> to vertically move the nip roller 7b between a position where the nip roller 7b is pressed against the driving roller 7a and a position where the nip roller 7b is separated from the driving roller 7a. The driving unit DU1 includes the motor M1 as a common driving source. A driving force of the motor M1 is transmitted to each component by a transmission mechanism <NUM> which forms a transmission path of the driving force. The motor M1 and the transmission mechanism <NUM> are concentratedly arranged outside (left side) the conveyance path RT in the widthwise direction (X direction) of the sheet.

First, the moving mechanism for the movable support member <NUM> will be described. <FIG> is a perspective view showing the cutting unit <NUM> and the portion of the moving mechanism for the movable support member <NUM> in the driving unit DU1. The cutting unit <NUM> in this embodiment is a mechanism for cutting a sheet in the widthwise direction by moving, in the X direction, a scan unit <NUM> including a cutter blade. The scan unit <NUM> is movably supported by a guide member <NUM> extending in the X direction. The guide member <NUM> supports the motor M2 as a driving source, and a belt transmission mechanism <NUM> is provided inside the guide member <NUM>. The belt transmission mechanism <NUM> includes a driving pulley and a driven pulley spaced apart from each other in the X direction, and an endless belt wounded between the pulleys. The scan unit <NUM> is fixed to the endless belt. When the motor M2 causes the driving pulley to rotate, the endless belt travels and the scan unit <NUM> moves.

The movable support member <NUM> is arranged adjacent to the guide member <NUM> in the sheet conveyance direction. Upon moving the scan unit <NUM>, the movable support member <NUM> is moved to avoid interference between the scan unit <NUM> and the movable support member <NUM>. Refer to <FIG> in addition to <FIG>. <FIG> are views for explaining the moving mechanism for the movable support member <NUM>. <FIG> shows a state in which the movable support member <NUM> is located in the support position, and <FIG> shows a state in which the movable support member <NUM> is located in the retreat position. The movable support member <NUM> is provided so as to be pivotable with an X-direction shaft 17a as the pivot center, and a gear <NUM> is fixed to the shaft 17a. Further, the movable support member <NUM> is biased to the support position by an elastic member 17b. The elastic member 17b is a coil spring. One end of the elastic member 17b is fixed to the movable support member <NUM>, and the other end thereof is fixed to the main body of the printing apparatus <NUM>.

The transmission mechanism <NUM> includes a gear train formed by gears <NUM> to <NUM>. The driving force of the motor M1 is transmitted to the gear <NUM> via the gear train, and the movable support member <NUM> is caused to pivot to the retreat position as shown in <FIG>. In the retreat position, the movable support member <NUM> retreats (moves diagonally downward) from the scan space of the scan unit <NUM>. Each arrow in <FIG> indicates the rotation direction of each component.

Among the gears <NUM> to <NUM>, the gear <NUM> is a gear provided with an electromagnetic clutch between an input gear and an output gear, and transmission of the driving force can be connected/disconnected by connecting/disconnecting the electromagnetic clutch. When the electromagnetic clutch is in a connection state, if the motor M1 is rotated in the N1 direction, the moving mechanism is operated and the movable support member <NUM> pivots from the support position to the retreat position. However, when the electromagnetic clutch is in a disconnection state, even if the motor M1 is rotated, the movable support member <NUM> does not pivot. After the movable support member <NUM> moves to the retreat position, by switching the electromagnetic clutch from the connection state to the disconnection state, the movable support member <NUM> returns to the support position due to the bias of the elastic member 17b.

Next, the state switching mechanism for the discharge unit <NUM> will be described with reference to <FIG>, <FIG>, <FIG>, and <FIG>. <FIG> are views for explaining the operation. <FIG> shows a case in which the discharge unit <NUM> is in the nip released state (a case in which the nip roller 7b is located in an upper retreat position), and <FIG> shows a case in which the discharge unit <NUM> is in the nip state (a case in which the nip roller 7b is located in a lower nip position). <FIG> is a perspective view of a support structure of the nip roller 7b.

A plurality of the nip rollers 7b are arranged in the X direction, and each nip roller 7b is supported by a support unit <NUM>. Each support unit <NUM> is supported by a frame <NUM> via a coupling member <NUM>.

The support unit <NUM> includes a main body portion 33a, and a movable portion 33b supported so as to be displaceable in the Z direction with respect to the main body portion 33a. The nip roller 7b is rotatably supported by the movable portion 33b. The movable portion 33b includes a projection portion 33c projecting in the X direction, and an elastic member 33d which biases the movable portion 33b to the nip position is provided between the main body portion 33a and the movable portion 33b.

An operation shaft <NUM> extends in the X direction. The operation shaft <NUM> includes an arcuate peripheral surface 31a, and also includes a recess portion 31b in a part of the peripheral surface. An operation arm <NUM> is an L-shaped member provided for each nip roller 7b, and pivotable with a shaft 32a in its central portion as the pivot center. An abutting portion P1 of the operation arm <NUM> abuts against the peripheral surface 31a of the operation shaft <NUM>, and an abutting portion P2 thereof abuts against the projection portion 33c of the movable portion 33b from below.

As shown in <FIG>, in the nip released state, the abutting portion P1 of the operation arm <NUM> abuts against the peripheral surface 31a of the operation shaft <NUM> so that the clockwise pivot of the operation arm <NUM> is restricted. Accordingly, the operation arm <NUM> restricts the downward movement of the movable portion 33b and the nip roller 7b is separated from the driving roller 7a. As shown in <FIG>, if the operation shaft <NUM> is rotated, the abutting portion P1 falls from the peripheral surface 31a into the recess portion 31b. This frees the clockwise pivot of the operation arm <NUM>, and the restriction on the downward movement of the movable portion 33b by the operation arm <NUM> is released. The movable portion 33b is moved downward due to the bias of the elastic member 33d, and the discharge unit <NUM> is set in the nip state in which the nip roller 7b is pressed against the driving roller 7a.

Referring to <FIG>, a gear <NUM> is fixed to the end portion of the operation shaft <NUM>. The transmission mechanism <NUM> includes a gear train formed by the gear <NUM> and gears <NUM> to <NUM>. The driving force of the motor M1 is transmitted to the gear <NUM> via the gear train, and the operation shaft <NUM> is rotated. The gear <NUM> is provided with a detection piece 29a. By detecting the detection piece 29a by the sensor <NUM>, the rotation position of the operation shaft <NUM> is specified and it is determined whether the discharge unit <NUM> is in the nip state or the nip released state. The sensor <NUM> is an optical sensor such as a photointerrupter.

When operating the state switching mechanism, the motor M1 is rotated in the N2 direction opposite to the N1 direction which is a predetermined rotation direction for moving the movable support member <NUM>. The gear <NUM> incorporates a one-way clutch, so that it transmits rotation of the motor M1 in the N2 direction but does not transmit rotation in the N1 direction. <FIG> is a perspective view of the gear <NUM>, and <FIG> are exploded perspective views of the gear <NUM>.

The gear <NUM> has an arrangement in which a small-diameter gear 26c and a large-diameter gear 26d are arranged on a common shaft 26a and held on the shaft 26a by a retaining ring 26e in the end portion of the shaft 26a. The shaft 26a is provided with a pin 26b. Engagement between the small-diameter gear 26c and the pin 26b enables transmission of a rotational force between the shaft 26a and the small-diameter gear 26c regardless of the rotation direction. On the other hand, a one-way clutch 26f is provided between the large-diameter gear 26d and the shaft 26a, and the rotational force is transmitted between the shaft 26a and the large-diameter gear 26d only in one rotation direction.

With the arrangement described above, by using the rotation direction of the motor M1, the electromagnetic clutch of the gear <NUM>, and the one-way clutch 26f of the gear <NUM>, it is possible to move the movable support member <NUM> and vertically move the nip roller 7b independently. That is, when moving the movable support member <NUM> to the retreat position, the motor M1 is rotated in the N1 direction and the electromagnetic clutch of the gear <NUM> is set in the connection state. This allows the movable support member <NUM> to operate. At this time, due to the action of the one-way clutch 26f, the gear <NUM> does not transmit the rotational force. When moving the movable support member <NUM> to the support position, the electromagnetic clutch of the gear <NUM> is set in the disconnection state. When moving the nip roller 7b to the nip position or the retreat position, the motor M1 is rotated in the N2 direction and the electromagnetic clutch of the gear <NUM> is set in the disconnection state.

<FIG> is a schematic view of the driving unit DU2. The driving unit DU2 forms a roller driving mechanism for driving the driving roller 7a of the discharge unit <NUM> and the driving roller 8a of the discharge unit <NUM>. The driving unit DU2 also forms a path switching mechanism for selectively switching the discharge path to the discharge path RT1 or RT2 by switching the position of the path switching member <NUM>. The driving unit DU2 includes the motor M3 as a common driving source. A driving force of the motor M3 is transmitted to each component by a transmission mechanism <NUM> which forms a transmission path of the driving force. The motor M3 and the transmission mechanism <NUM> are concentratedly arranged outside (left side) the conveyance path RT in the widthwise direction (X direction) of the sheet. That is, in this embodiment, the motor M1 and transmission mechanism <NUM> of the driving unit DU1 and the motor M3 and transmission mechanism <NUM> of the driving unit DU2 are concentratedly arranged on the left side of the conveyance path RT. With this arrangement, it is possible to suppress expansion of spaces for the mechanism systems on both sides of the conveyance path RT in the X direction. Thus, it is possible to store the mechanism systems in a compact driving space while achieving multifunctional driving.

First, the roller driving mechanism will be described. <FIG> is a partially enlarged view of <FIG>, and <FIG> is a view for explaining a mode of transmitting a driving force by the transmission mechanism <NUM>. A plurality of the driving rollers 7a are arranged in the X direction so as to be spaced apart from each other, and fixed to a roller shaft 7c extending in the X direction. A gear 43d is fixed to one end portion of the roller shaft 7c. Similarly, a plurality of the driving rollers 8a are arranged in the X direction so as to be spaced apart from each other, and fixed to a roller shaft 8c extending in the X direction. A gear 42d is fixed to one end portion of the roller shaft 8c.

The transmission mechanism <NUM> includes a gear train formed by gears <NUM> and 42a to 42c. The driving force of the motor M3 is transmitted to the gear 42d via the gear train, and the roller shaft 8c is rotated. The transmission mechanism <NUM> also includes a gear train formed by the gear <NUM> and gears 43a to 43c. The driving force of the motor M3 is transmitted to the gear 43d via the gear train, and the roller shaft 7c is rotated. As shown in <FIG>, if the motor M3 is rotated in the N3 direction, each of the rollers 7a and 8a is rotated and the sheet is conveyed.

With reference to <FIG>, <FIG>, the path switching mechanism will be described. <FIG> shows the position (to be referred to as the RT2 selection position) of the path switching member <NUM> for selecting the discharge path RT2, and <FIG> shows the position (to be referred to as the RT1 selection position) of the path switching member <NUM> for selecting the discharge path RT1. The path switching position (branch point BR) of the path switching member <NUM> is located on the conveyance path RT between the discharge unit <NUM> and the discharge unit <NUM>.

The path switching member <NUM> includes the shaft 14a extending in the X direction. The shaft 14a is rotatably supported, and the path switching member <NUM> pivots with the shaft 14a as the pivot center. The path switching member <NUM> includes a guide portion 14b which forms a sheet guide surface, a lever portion 14c, and an elastic member 14d. The elastic member 14d in this embodiment is a screw spring, and biases the path switching member <NUM> to the RT1 selection position.

The transmission mechanism <NUM> includes a gear <NUM> including a cam portion 46a. The cam portion 46a abuts against the lever portion 14c of the path switching member <NUM>, thereby causing the path switching member <NUM> to pivot from the RT1 selection position to the RT2 selection position. The pivot amount of the gear <NUM> is detected by the sensor <NUM>. The sensor <NUM> is an optical sensor such as a photointerrupter which detects a detection piece 46b provided in the gear <NUM>.

As a component for rotating the gear <NUM>, the transmission mechanism <NUM> includes a pendulum gear G. The pendulum gear G includes a gear <NUM> and a gear <NUM> meshing with each other. The gear <NUM> meshes with the gear <NUM>. If the gear <NUM> meshes with the gear <NUM> due to a swinging motion, the driving force is transmitted. If the gear <NUM> does not mesh with the gear <NUM>, the transmission of the driving force is cut off. If the motor M3 is rotating in the N3 direction as shown in <FIG>, the pendulum gear G swings in the D1 direction, so the driving force is not transmitted to the gear <NUM>. If the motor M3 is rotating in the N4 direction which is a predetermined rotation direction opposite to the N3 direction as shown in <FIG>, the pendulum gear G swings in the D2 direction, so that the driving force is transmitted to the gear <NUM>. This allows the path switching member <NUM> to operate. That is, the cam portion 46a abuts against the lever portion 14c of the path switching member <NUM>, and this can cause the path switching member <NUM> to pivot to the RT2 selection position. If the gear <NUM> further rotates and the cam portion 46a passes through the lever portion 14c, the path switching member <NUM> returns to the RT1 selection position due to the bias of the elastic member 14d.

During sheet conveyance by the conveyance units <NUM> and <NUM>, the motor M3 rotates in the N3 direction so the gear <NUM> does not mesh with the gear <NUM>. Accordingly, the position of the path switching member <NUM> does not change. If the motor M3 is rotating in the N4 direction, the driving rollers 7a and 8a rotate in a direction opposite to the sheet conveyance direction. However, by switching the discharge path by the path switching member <NUM> at a timing other than during a printing operation, a sheet is not conveyed reversely. Alternatively, for example, a one-way clutch may be provided in any of the gears involved in the transmission of the driving force to each of the roller shafts 7c and 8c so that only the rotation in the sheet conveyance direction is transmitted to each of the roller shafts 7c and 8c. In this case, it is possible to switch the discharge path during a printing operation.

The printing apparatus <NUM> is provided with a plurality of conveyance mechanisms (discharge units <NUM> and <NUM>) on the downstream side of the printhead <NUM>. They generate a sheet conveyance force, but since they nip the printed sheet, the printed surface of the sheet may be scratched due to the pressing force of the conveyance mechanism, or the conveyance accuracy may be decreased due to a difference in conveyance speed between the conveyance mechanisms. In this embodiment, as has been described above, it is configured such that the state of the discharge unit <NUM> can be switched between the nip state and the nip released state. Therefore, in a case in which a sheet is sufficiently long so that the discharge unit <NUM> alone can generate an enough conveyance force or in a case of handling a sheet which is easily damaged, the discharge unit <NUM> can be set in the nip released state so as not to nip the sheet. On the other hand, in a case of a short sheet, the discharge unit <NUM> can be set in the nip state to ensure the conveyance force. Thus, it is possible to convey sheets of different sheet lengths and prevent generation of an unnecessary load on the sheet during the conveyance.

A processing example of the control unit <NUM> related to state switching of the discharge unit <NUM> and the like will be described below. <FIG> is a flowchart illustrating an example of processing performed by the processing unit 18a. In this embodiment, the processing is started with the discharge unit <NUM> set in the nip released state.

In step S <NUM>, preparation processing is performed. Here, the processing based on user's setting contents is performed. For example, switching of the discharge path by the path switching member <NUM> is performed. The processing example described blow assumes a case in which the discharge path RT1 is selected. In step S2, a printing operation is started. By alternately repeating intermittent conveyance of a sheet by the conveyance unit <NUM> and an operation including moving the carriage <NUM> and ink discharge by the printhead <NUM>, an image is printed on the sheet. Further, the respective driving rollers 7a and 8a of the discharge units <NUM> and <NUM> are rotated.

In step S3, based on a detection result of a sheet detection sensor (not shown), it is determined whether the sheet has reached a predetermined position. If the sheet has reached, the process advances to step S4. The predetermined position here is a position where the leading end of the sheet has passed through the movable support member <NUM> (for example, a position where the leading end of the sheet has reached the discharge unit <NUM>). In step S4, the movable support member <NUM> is moved to the retreat position. Since the leading end of the sheet has already passed through the movable support member <NUM>, even if the movable support member <NUM> is moved to the retreat position, the sheet is supported within the conveyance path RT. Thereafter, the printing operation is performed up to the image printing range set by the user in advance. In step S5, the sheet is conveyed to the position where it is to be cut by the cutting unit <NUM>, and the conveyance is temporarily stopped. The conveyance amount at this time is determined based on, for example, the sheet length after cutting set by the user in advance.

In step S6, it is determined whether the sheet length after cutting is equal to or smaller than a threshold (equal to or shorter than a predetermined length). <FIG> is a view for explaining a predetermined length L which serves as a criterion for the determination. In <FIG>, a length L1 indicates the path length of the conveyance path RT from the cutting unit <NUM> (more specifically, the cutting position) to the discharge unit <NUM> (more specifically, the nip position). A length L2 indicates the path length of the conveyance path RT (discharge path RT1) from the discharge unit <NUM> (more specifically, the nip position) to the discharge unit <NUM> (more specifically, the nip position). The predetermined length L is expressed by L = L1 + L2, which is the path length from the cutting unit <NUM> to the discharge unit <NUM>.

The predetermined length L is shorter than the minimum length of the sheet after cutting which is supposed to be conveyed. For example, due to the specifications of the printing apparatus <NUM>, if the minimum length of the sheet after cutting is <NUM>, the predetermined length L is shorter than <NUM>. Similarly, the length L2 is shorter than the minimum length of the sheet after cutting which is supposed to be conveyed. Thus, the sheet of the minimum length can be nipped and conveyed by at least one of the conveyance units <NUM> and <NUM>.

If the sheet length of the sheet after cutting is equal to or shorter than the predetermined length L, the leading end of the sheet has not reached the discharge unit <NUM>. Then, the discharge unit <NUM> is set in the nip state in step S7 to use the discharge unit <NUM> to convey the sheet (<FIG>). The short sheet after cutting can be reliably discharged. If the sheet length of the sheet after cutting is longer than the predetermined length L, the leading end of the roll sheet R has reached the discharge unit <NUM>. Then, the process does not advance to step S7 and the discharge unit <NUM> is maintained in the nip released state (<FIG>).

In step S8, the roll sheet R is cut by the cutting unit <NUM>. In step S9, the respective driving rollers 7a and 8a of the discharge units <NUM> and <NUM> are rotated, and the sheet after cutting is conveyed to the stacking section <NUM>. In this embodiment, due to the configuration of the apparatus, the driving roller 7a is rotated even if the discharge unit <NUM> is in the nip released state. However, since the nip roller 7b is not pressed against the driving roller 7a, substantially no conveyance force is generated.

In step S <NUM>, the movable support member <NUM> is returned to the support position. In step S <NUM>, based on a detection result of the sheet detection sensor, it is determined whether the sheet after cutting has been discharged to the stacking section <NUM>. For example, if it is detected that the trailing end of the sheet has passed through the discharge unit <NUM>, it is determined that the sheet has discharged to the stacking section <NUM>. If it is determined that the sheet has been conveyed to the stacking section <NUM>, the process advances to step S12 and the rotation of each of the driving rollers 7a and 8a of the discharge units <NUM> and <NUM> is stopped.

In step S13, it is determined whether the discharge unit <NUM> has been set in the nip state by the processing in step S7. If the discharge unit <NUM> has been set in the nip state, the process advances to step S14 and the discharge unit <NUM> is returned to the nip released state. With the processing described above, the process (one job) ends.

With the procedure described above, it is possible to discharge the sheet while selecting, in accordance with the sheet length after cutting, whether to press the nip roller 7b against the driving roller 7a or separate the nip roller 7b from the driving roller 7a. Thus, it is possible to appropriately convey the sheets of different sheet lengths. The processing example shown in <FIG> is merely an example. For example, it may be controlled such that as soon as the sheet is held by the discharge unit <NUM>, the discharge unit <NUM> in the nip state is switched to the nip released state. Alternatively, if the discharge unit <NUM> is set in the nip state in step S7, a next job may be waited without returning the discharge unit <NUM> to the nip released state in step S14. In this case, the discharge unit <NUM> may be returned to the nip released state at the beginning of the next job, or the discharge unit <NUM> may be returned to the nip released state if it is determined that the sheet length is longer than the predetermined length L in step S6 for the next job. Note that when discharging the sheet from the discharge path RT2, the discharge unit <NUM> is set in the nip released state. However, as needed, the discharge unit <NUM> may be set in the nip state.

In the embodiment described above, the arrangement has been exemplarily shown in which two discharge paths (RT1 and RT2) are provided. However, the number of the discharge paths may be three or more, or may be one. Further, although the reversing section <NUM> is provided in the discharge path RT1, the arrangement may be employed in which no reversing section <NUM> is provided.

Claim 1:
A printing apparatus (<NUM>) comprising:
printing means (<NUM>) arranged to perform printing on a sheet;
first conveyance means (<NUM>) configured to convey the sheet to the printing means with nipping the sheet;
second conveyance means (<NUM>) provided on a downstream side of the printing means in a conveyance direction of the sheet and configured to convey the sheet with nipping the sheet, the sheet being conveyed by the first conveyance means;
third conveyance means (<NUM>) provided on a downstream side of the second conveyance means in the conveyance direction and configured to convey the sheet with nipping the sheet;
cutting means (<NUM>) configured to cut the sheet; and
switching means (DU1) configured to switch a nip state of the second conveyance means and a released state in which the nip state is released,
characterized in that
the cutting means (<NUM>) is arranged at a position between the printing means (<NUM>) and the second conveyance means (<NUM>) in a conveyance path of the sheet, and
the switching means (DU1) switches the nip state and the released state in accordance with a length of the sheet from a cut position on the sheet by the cutting means (<NUM>) to a leading end of the sheet.