Patent Grant
8585047
1. Field of the Invention
The present invention relates to a sheet conveyance apparatus and a recording apparatus that records an image on a sheet.
2. Description of the Related Art
In an image forming apparatus discussed in Japanese Patent Application Laid-Open No. 2005-156974, misregistration and a misaligned posture of the tip of a long sheet are corrected by causing the long sheet to move along a bump guide in parallel along a conveyance direction by a skew roller pair whose rotation surface is tilted toward the bump guide. Twist tension generated in the long sheet is reduced by generating a loop in a loop conveyance unit provided upstream of the guide immediately before the long sheet being caused to move along the bump guide so that skew correction processing with a reduced load can be performed.
Then, image formation with less skew is realized by sandwiching the sheet between a line feed roller pair on the downstream side and restarting conveyance after the skew roller pair being detached.
However, in a configuration, such as that discussed in Japanese Patent Application Laid-Open No. 2005-156974, in which the skew roller pair is detached after the skew at the tip of a long sheet is corrected to allow the long sheet to be conveyed, an issue actually arises of deteriorating conveyance precision with the sheet skewed during conveyance. Reasons for the issue include a factor that because the skew roller pair is detached, torsional tension of the long sheet directly affects the line feed roller pair to deteriorate conveyance balance, resulting in the skew.
If the long sheet is made to be conveyed along the bump guide by the skew rollers, there is an issue that satisfactory image quality cannot be obtained due to an occurrence of surface defects of the sheet because the sheet is conveyed in a state in which the surface thereof is slidingly rubbed by the skew rollers.
Japanese Patent Application Laid-Open No. 2007-225947 discusses a printing apparatus in which a pair of regulatory guides on the left and right sides is provided on a paper path route of roll paper to prevent meandering. Meandering of the roll paper can be prevented by moving the left and right guides to pushed-in positions narrower than the width of the roll paper to correct the posture of the roll paper and then, moving the roll paper width guide position.
In an apparatus discussed in Japanese Patent Application Laid-Open No. 2007-225947, a conveyance roller is provided upstream and downstream of a paper width guide to sandwich and convey roll paper. When meandering is corrected, pressure contact of the conveyance rollers is released and an operation of pushing in roll paper edges further narrower than the paper width by a guide unit is performed. Also, the position of the guide unit is moved according to the width dimension of the roll paper input into the apparatus in advance.
However, to respond to user needs more wide-ranging than in the past, issues cited below manifest themselves when an attempt is made to obtain better printing results by conveying various media with higher precision than in the past:
According to an aspect of the present invention, an apparatus includes a first conveyance unit configured to convey a sheet, a first guide located downstream of the first conveyance unit in a conveyance direction and configured to guide a first side end of the conveyed sheet, a skew unit configured to convey the sheet in an oblique direction to come closer to the first guide, a second guide configured to contact a second side end opposite the first side end to guide the second side end, a second conveyance unit located downstream of the first guide in the conveyance direction, and a control unit configured to perform control so that, after conveying the sheet by the skew unit with the first guide contacting the first side end while the second guide is separated from the second side end, the second guide moves to a position close to the second side end.
According to exemplary embodiments of the present invention, a sheet conveyance apparatus capable of suppressing skew of a sheet with high precision can be provided.
A recording apparatus using an inkjet system according to a first exemplary embodiment of the present invention is a high-speed line printer that uses a continuous sheet wound like a roll and supports both one-sided printing and two-sided printing. For example, the recording apparatus is suitable for printing of a large quantity of printing in a printing laboratory or the like. The present invention can be widely applied to printing apparatuses such as printers, multifunction peripherals, copying machines, facsimile machines, and manufacturing equipment of various devices. Moreover, in addition to printing processing, the present invention can be applied to sheet processing apparatuses that perform various kinds of processing (such as recording, working, coating, irradiation, reading, and inspection) on roll sheets.
The sheet feeding unit 1 is a unit that houses and feeds a continuous sheet wound like a roll. The sheet feeding unit 1 can hold two rolls R1 and R2 and is configured to alternatively pull out and feed the roll. The number of rolls that can be housed is not limited to two and one roll or three rolls or more may be housed.
The decurling unit 2 is a unit that reduces curling (warping) of a sheet fed from the sheet feeding unit 1. The decurling unit 2 uses two pinch rollers for one driving roller to reduce curling by a decurling force by causing the sheet allowed to pass to be curved in such a way that warping opposite to the curling is given.
The skew correction unit 3 is a unit that corrects the skew (tilt to the original traveling direction) of a sheet that has passed through the decurling unit 2. The skew of a sheet is corrected by pushing a sheet edge on the side to be a reference against a guide member.
The printing unit 4 is a unit that forms an image on a sheet by a print head 14, which is a recording unit for a conveyed sheet. The printing unit 4 includes a plurality of conveyance rollers that convey a sheet. The print head 14 has a line print head in which nozzle lines of an inkjet system are formed in a range to cover the maximum width of a sheet whose usage is assumed. The printing unit 4 has a plurality of print heads arranged in parallel along the conveyance direction. In the present exemplary embodiment, the printing unit 4 has seven print heads corresponding to seven colors of C (cyan), M (magenta), Y (yellow), LC (light cyan), LM (light magenta), G (gray), and B (black). However, the number of colors and that of print heads are not limited to seven. As the inkjet system, a system using heater elements, a system using piezoelectric elements, a system using electrostatic elements, a system using MEMS elements or the like can be adopted. The respective colors of ink are supplied from ink tanks thereof to the print head 14 through ink tubes, respectively.
The inspection unit 5 is a unit that determines whether an image is correctly printed by optically reading an inspection pattern or image printed on a sheet by the printing unit 4 and inspecting the state of print head nozzles, sheet conveyance state, and image positions. The inspection unit 5 includes a CCD image sensor or CMOS image sensor as the scanner.
The cutter unit 6 is a unit that includes a mechanical cutter to cut a printed sheet to a predetermined length. The cutter unit 6 also includes a plurality of conveyance rollers to send out a sheet for the next process.
The information recording unit 7 is a unit that records print information (information specific to each image) such as the serial number and date on the back side of a cut sheet.
The drying unit 8 is a unit that dries attached ink in a short time by heating the sheet printed by the printing unit 4. Inside the drying unit 8, the ink attached side is dried by blowing hot air at least from below to the passing sheet. The drying method is not limited to the method of blowing hot air and may be a method of irradiating a sheet surface with electromagnetic waves (such as ultraviolet rays and infrared rays). The drying unit 8 also includes a conveyance belt and a conveyance roller to send out a sheet for the next process.
The sheet conveyance route from the sheet feeding unit 1 to the drying unit 8 described above is called a first route. The first route has a U-turn shape between the printing unit 4 and the drying unit 8 and the cutter unit 6 is positioned at some midpoint of the U-turn shape.
The sheet winding unit 9 (or reversing unit 9) is a unit to reverse a continuous sheet whose front-side printing is completed by temporarily winding the continuous sheet when two-sided printing is performed. The sheet winding unit 9 is provided on a route (loop path) (called a second route) from the drying unit 8 to the printing unit 4 through the decurling unit 2 for supplying the sheet passed through the drying unit 8 to the printing unit 4 again. The sheet winding unit 9 includes a rotating wind-up drum to wind up a sheet. A continuous sheet whose printing on the front side (first side) is completed and which is not yet cut is temporarily wound by the wind-up drum. When winding is completed, the wind-up drum rotates in the opposite direction to feed the wound sheet in the reverse order in which the sheet is wound to the decurling unit 2 before the sheet being fed to the printing unit 4. The sheet is reversed and thus, the rear side (second side) can be printed by the printing unit 4. A more concrete operation of the two-sided printing will be described below.
The discharge/conveyance unit 10 is a unit to convey a sheet cut by the cutter unit 6 and dried by the drying unit 8 to deliver the sheet to the sorter unit 11. The discharge/conveyance unit 10 is provided on a route (called a third route) different from the second route where the sheet winding unit 9 is provided. To selectively lead a sheet conveyed on the first route to one of the second route and the third route, a route switching mechanism having a movable flapper is provided at the branching position of the route.
The sorter unit 11 and the discharge tray 12 are provided near the side of the sheet feeding unit 1 and at an end of the third route. The sorter unit 11 is a unit that distributes and discharges printed sheets in groups to different trays of the discharge tray 12 if necessary. Sorted sheets are discharged to the discharge unit 12 composed of a plurality of trays. Thus, the third route is laid out to discharge a sheet to the opposite side of the printing unit 4 and the drying unit 8 across the sheet feeding unit 1 after passing below the sheet feeding unit 1.
The control unit 13 is a unit that manages control of each unit of the whole recording apparatus. The control unit 13 has a controller 15 including a central processing unit (CPU), memory, and various input/output (I/O) interfaces and a power supply. The operation of the recording apparatus is controlled based on commands from the controller 15 or a host apparatus 211 such as a host computer connected to the controller 15 via an I/O interface.
For a unit that requires high-speed data processing, a dedicated processing unit is provided. The image processing unit 207 performs image processing of print data handled by the printing apparatus. The image processing unit 207 converts the color space (for example, YCbCr) of input image data into the standard RGB color space (for example, sRGB). The image processing unit 207 also performs various kinds of image processing such as resolution conversions, image analysis, and image corrections on image data if necessary. Print data obtained after the above image processing is stored in the RAM 203 or the HDD 204. The engine control unit 208 performs driving control of the print head 14 of the printing unit 4 according to print data based on a control command received from the CPU 201 or the like. The engine control unit 208 further controls the transport mechanism of each unit inside the printing apparatus. The individual unit control unit 209 is a sub-controller to individually control each unit of the sheet feeding unit 1, the decurling unit 2, the skew correction unit 3, the inspection unit 5, the cutter unit 6, the information recording unit 7, the drying unit 8, the sheet winding unit 9, the discharge/conveyance unit 10, the sorter unit 11, and the discharge tray 12. Based on a command by the CPU 201, the individual unit control unit 209 controls the operation of each unit. An external interface 205 is an interface (I/F) to connect the controller to the host apparatus 211 and is a local I/F or a network I/F. The above components are connected by a system bus 210.
The host apparatus 211 is an apparatus serving as a feeding source of image data the printing apparatus is caused to print. The host apparatus 211 may be a general-purpose or dedicated computer or a dedicated imaging device such as an image capturing device, digital camera, and photo storage. If the host apparatus 211 is a computer, the OS, application software that generates image data, and a printer driver for the printing apparatus are installed into a storage apparatus of the computer. Incidentally, it is not necessary to realize all above processing by software and part or all of the above processing may be realized by hardware.
Next, the basic operation of printing will be described. The operation of one-sided printing and that of two-sided printing are different and thus, each type of printing will be described.
Thus, in one-sided printing, a sheet is processed by passing through the first route and the third route and does not pass through the second route. In summary, a sequence of operations (1) to (6) shown below is executed under the control of the control unit 13 in a one-sided printing mode:
After the front side printing sequence described above, the printing sequence is switched to the back side printing sequence. The wind-up drum of the sheet winding unit 9 rotates opposite to the direction for winding (clockwise in the drawing). The edge of the wound sheet (the sheet back end during winding becomes the sheet tip when the sheet is sent out) is fed into the decurling unit 2 along a route of a broken line in
Thus, in two-sided printing, a sheet is processed by passing through the first route, the second route, the first route, and the third route in this order. In summary, a sequence of operations (1) to (11) shown below is executed under the control of the control unit 13 in a two-sided printing mode:
Next, the skew correction unit 3 in a recording apparatus configured as described above will be described in more detail.
The skew correction unit includes a first driving roller 311, a first driven roller 312, a top surface guide 313, a bottom surface guide 314, a roller 315, a skew driving roller 316, a skew driven roller 317, a reference guide 318, and an auxiliary guide 319 from upstream.
The skew correction unit has a curved paper path of substantially 90 degrees between the first driving roller 311 and the roller 315. The skew correction unit includes a driving transmission unit that transmits driving from a loop R motor 231 (
The skew driving roller 316 rotates by being driven by a skew R motor 333. The skew driven roller 317 can be moved between a position in contact with the skew driving roller 316 by pressure by a skew R release motor 332 and a position away from the skew driving roller 316. The reference guide 318, which is a first guide, can be moved by a reference guide motor 331 in a direction crossing the conveyance direction. The reference guide 318 is moved by the reference guide motor 331 to the reference position of a first sheet side end, which is one side edge of a sheet. The reference guide 318 that has moved to the reference position comes into contact with the first sheet side end, which is one side edge of the sheet conveyed by the skew driving roller 316 in an oblique direction, and guides the first sheet side end to make a skew correction of the sheet.
Similarly, the auxiliary guide 319 can be moved by an auxiliary guide motor 334 in a direction crossing the conveyance direction. The auxiliary guide 319, which is a second guide, is moved to a position away from the reference guide 318 by a distance corresponding to the sheet width by the auxiliary guide motor 334 to guide a second sheet side end on the opposite side of the first sheet side end. The sheet is prevented from being skewed by both side ends of the sheet being guided by the reference guide 318 and the auxiliary guide 319 away from each other by the sheet width.
The printing unit 4 has a second driving roller 411 and a second driven roller 412. The second driven roller 412 can be moved between a position in contact with the second driving roller 411 by pressure by an imaging R release motor 431 and a position away from the second driving roller 411.
In
A sensor unit 130 is a group of sensors to detect the state of the apparatus. In the present exemplary embodiment, in addition to a first sheet tip detection sensor 351 and a second sheet tip detection sensor 451, the recording apparatus has a temperature sensor provided to detect an environmental temperature sensor (not illustrated) and various sensors.
A motor driver 170 drives a loop R motor 231 and a loop guide motor 222. The first driving roller 311 is driven by driving the loop R motor 231 to have the sheet conveyed in a downstream direction. The top surface guide 313 is opened/closed by driving the loop guide motor 222.
A motor driver 180 drives the skew R motor 333, the auxiliary guide motor 334, the skew R release motor 332, and the reference guide motor 331. The skew driving roller 316 is driven by driving the skew R motor 333 to have the sheet conveyed obliquely to the reference guide. Skew rollers are attached or detached by driving the skew R release motor 332. The auxiliary guide 319 is driven by the auxiliary guide motor 334 and the reference guide 318 is driven by the reference guide motor 331 so that each guide is brought into contact with the sheet edge on the side on which each is arranged.
A motor driver 190 drives the imaging R release motor 431. The second driven roller 412 is attached or detached by driving the imaging R release motor 431.
When paper feeding is started, the controller 15 drives the loop R motor 231 so that the first driving roller 311 starts to rotate. As illustrated in
If, in step S102, the sheet tip is detected by the first sheet tip detection sensor 351 arranged in the skew correction unit 3 (YES in step S102), processing proceeds to step S103. In step S103, the controller 15 stops the loop R motor 231 and all conveyance rollers upstream thereof simultaneously in the timing when the sheet tip reaches between the skew driving roller 316 and the skew driven roller 317.
In step S104, as illustrated in
After a loop sufficient for skew correction is formed in the continuous sheet, in step S108, the controller 15 drives the skew driving roller 316 at a speed so that, as illustrated in
The conveyance direction of the skew driving roller 316 is tilted toward a direction in which the continuous sheet is pressed against the reference guide 318 and thus, the side end of the continuous sheet is pressed against the reference guide 318 while the continuous sheet is being conveyed in the normal conveyance direction. The continuous sheet is conveyed while the side end thereof is slidingly rubbed against the reference guide 318 to correct the skew.
If, in step S109, the sheet tip is detected by the second sheet tip detection sensor 451 arranged in the printing unit 4 (YES in step S109), processing proceeds to step S110, in which the controller 15 stops the loop R motor 231, the skew R motor 333, and all conveyance rollers upstream thereof simultaneously.
In step S111, the controller 15 drives the imaging R release motor 431 to sandwich the sheet tip, as illustrated in
Thus, according to the first exemplary embodiment, when a sheet conveyed by the first driving roller 311 is detected by the first sheet tip detection sensor 351, a loop is generated between the first driving roller 311 and the skew driving roller 316. The skew driving roller 316 is driven to have the sheet conveyed to the printing unit 4 while the sheet is brought into contact with the reference guide 318. When the conveyed sheet is detected by the second sheet tip detection sensor 451, the auxiliary guide 319 is moved to the sheet edge position and the skew is prevented by making the sheet to be conveyed while both edges of the sheet are brought into contact with the reference guide 318 and the auxiliary guide 319.
According to the first exemplary embodiment, a loop is generated to reduce torsional tension of a continuous sheet and, therefore, the continuous sheet can be made to smoothly move along the reference guide 318 while causing a skew unit to convey the continuous sheet so that the skew at the tip of the continuous sheet can easily be corrected.
Moreover, an influence of torsional tension of a continuous sheet on the printing unit 4 can be reduced by sandwiching the sheet between conveyance units of the printing unit 4 and while the skew at the tip of the sheet is corrected and guiding both side ends of the continuous sheet by the reference guide 318 and an auxiliary guide 319.
Through a sequence of operations, the skew can be suppressed when conveyance is restarted and a sheet conveyance apparatus with less disturbed images can be provided.
The skew correction unit includes, as illustrated in
Like in the first exemplary embodiment, when a continuous sheet conveyed up to the printing unit 4 while being brought into contact with the reference guide 318 by a skew unit is detected by the second sheet tip detection sensor 451, driving of each conveyance roller and the skew unit is stopped.
Then, the sheet tip is sandwiched between the second driving roller 411 and the second driven roller 412 and the skew driven roller 317 is moved away from the skew driving roller 316. In this state, the auxiliary guide 319′ retracted from the sheet edge position moves to the sheet edge position to perform skew prevention processing by pressing the edge of the continuous sheet in a direction crossing the conveyance direction.
The block diagram of the control unit in the present exemplary embodiment has the same configuration as that in the first exemplary embodiment and thus, an illustration and a description thereof will not be repeated.
According to the second exemplary embodiment, a continuous sheet can be made to be conveyed by reliably guiding the continuous sheet with a simple configuration that does not use a sensor or a special control unit irrespective of the width tolerance of a sheet.
Next, a third exemplary embodiment of the present invention will be described.
In a print area 110 downstream of the first conveyance roller pair, seven line print heads 14a to 14g corresponding to each color are arranged along the sheet conveyance direction. The line print heads 14a to 14g and the pinch rollers 104a to 104g are alternately arranged one by one. Platens 112a to 112g are provided at positions opposite to the print heads 14a to 14g respectively to support the sheet S. Both sides of the sheet S are nipped by a roller pair and supported by a platen at each of positions opposite to the print heads 14a to 14g so that a behavior of sheet conveyance is stabilized. Particularly when a sheet is first introduced, the sheet tip passes through a plurality of nip positions in a short period so that lifting of the sheet tip is suppressed, leading to stable introduction of the sheet.
A loop area 156 forms a loop shape on a sheet and a loop guide 157 controls the loop shape. Meandering correction guides 153 and 154, which are a pair of edge guide members, are arranged at two locations opposite to both edges of the sheet near the loop area 156 on the downstream side. The meandering correction guide 153 guides sheet edges after coming into contact with at least one side edge of the sheet. Further, sheet edge sensors 151 and 152, which are sheet edge detection units to detect sheet edge positions, are provided in the vicinity thereof on the downstream side. The configuration of the meandering correction guide and that of the sheet edge sensor will be described with reference to
Second sheet edge sensors 160 and 161 are second sheet edge detection units to detect the sheet edge position. A second movement guide 185 can move the second sheet edge sensors to any position in the sheet width direction. The printing unit 4 also includes a scanner 170, scanner rollers 172 and 174 that convey a sheet before or after the scanner, and pinch rollers 171 and 173 to press the sheet. A second loop area 175 forms a loop of a sheet between the scanner 170 and a cutter 182. A second loop guide 176 controls the loop shape. Second meandering correction guides 177 and 178 are second edge guide members that guide sheet edges by coming into contact with at least one side edge of the sheet. A third movement guide 179 moves the second meandering correction guides to any position in the sheet width direction. A pre-cutter conveyance roller 181 is arranged downstream of the second meandering correction guides and a pinch roller 180 presses the sheet.
Operations of sheet conveyance in the above configuration will be described. A meandering correction operation is described in the flow chart in
The meandering correction guides 153 and 154 are, as illustrated in
Subsequently, the sheet tip portion is conveyed by the conveyance roller pair of the print unit. Here, to carry out sheet conveyance of sheet edges along the meandering correction guides 153 and 154 against a force to meander the sheet, the optimum configuration is to enable the sheet to easily rotate using the meandering correction guides 153 and 154 as a fulcrum. In the present configuration, the loop area 156 is provided upstream of the meandering correction guides 153 and 154. Since a sheet can be moved somewhat freely in the sheet width direction in the loop area, the meandering correction guide 153 or 154 is used as a fulcrum to make the sheet downstream therefrom rotatable. Thus, even if a force to meander acts on a sheet, the sheet can be conveyed easily along the meandering correction guides 153 and 154. While it is effective to increase a pressing force of a conveyance roller to improve feeding precision and an equivalent pressure is applied also in the present configuration, improved feeding precision can be made compatible with meandering corrections for the reason described above. If a pressing force (nipping force) of the conveyance roller is set lower or an operation to release a nip is performed halfway through conveyance to make a meandering correction easier, precision of the conveyance direction disadvantageously deteriorates even though meandering can be corrected. Forces that generate meandering by a conveyance roller pair include, for example, nonuniformity of a pressing force of a pinch roller in the sheet width direction and cylindricity (outside diameter error) of each roller in the sheet width direction. If, in contrast to the present configuration, a conveyance roller pair is provided also upstream of the meandering correction guides 153 and 154, a sheet may be constrained both upstream and downstream of the meandering correction guides so that the posture of the sheet cannot be changed by the meandering correction guides 153 and 154. As a result, depending on the type of sheet to be used, a malfunction such as buckling of the sheet or a crimped edge may occur. Such a malfunction is more likely to occur particularly when stiffness of the sheet is low.
After the sheet tip portion passes through the print area 110, in step S3, the controller 300 detects the sheet edge position by the second sheet edge sensors 160 and 161. In step S4, the controller 300 determines the amount of movement to cause the second meandering correction guides 177 and 178 to move to a position aligned with sheet edges based on the sheet edge position detection result. Then, the controller 300 moves the second meandering correction guides 177 and 178 by the determined amount of movement to move the second meandering correction guides 177 and 178 to the position aligned with sheet edges. The sheet tip generates a loop in the second loop area 175 after passing through the scanner 170 before being conveyed to between the second meandering correction guides 177 and 178 fitting to the sheet width. Subsequently, the sheet is conveyed by the pre-cutter roller pair (180 and 181) and is cut to desired sizes by the cutter 182 if necessary. Like the configuration upstream of the print area, an integral movable configuration may be adopted for the second sheet edge sensors 160 and 161 and the second meandering correction guides 177 and 178 by arranging both at close positions. Thus, the position of the second meandering correction guides 177 and 178 is aligned with sheet edges based on detection results by the second sheet edge sensors and, therefore, an alignment error of the guides to the sheet can be reduced so that an excellent meandering correction can be made. In an apparatus that has, like the present configuration, a plurality of heads and a wide print area, a higher meandering correction effect can be expected by arranging the second meandering correction guides also downstream of the print area to control a behavior of the sheet before and after the print area. Moreover, the second meandering correction guides 177 and 178 are provided near the cutter 182 on the upstream side and, therefore, meandering when the sheet is cut can be reduced so that excellent sheet cutting precision can be ensured. Further, the configuration has the second loop area 175 arranged near the second meandering correction guides 177 and 178 on the upstream side and the pre-cutter roller pair (180 and 181) arranged on the downstream side and, therefore, like upstream of the print area, an excellent meandering correction can be made without causing buckling of the sheet or broken edges.
Next, the operation when a sheet is conveyed in a direction opposite to the normal conveyance direction (in a direction opposite to the direction A) to rewind the sheet will be described with reference to the flowchart in
In the above exemplary embodiments, the printing unit 4 has a line print head of each color provided therein, but a similar configuration can also be implemented by another configuration, for example, a serial single print head. The meandering correction guide may have a configuration in which one side that comes into contact with a sheet edge presses against the sheet edge with an elastic member such as a spring. In this case, a slight positioning error of the meandering correction guide to the sheet edge can be absorbed depending on the type of sheet and thus, a margin for sheet buckling is further increased. The meandering correction guide can achieve an effect to a sheet edge even on one side. A configuration in which the sheet is pressed onto one side by, for example, a skew roller may be adopted.
A printing apparatus according to the exemplary embodiments described above has an arrangement relationship that a conveyance roller pair to convey a sheet using a nip is provided upstream of the printing unit 4, sheet edge sensors and meandering correction guides are provided further upstream thereof, and a loop area is provided still further upstream thereof. The printing apparatus also has the arrangement relationship that sheet edge sensors and meandering correction guides are provided also downstream of the printing unit and a loop area is further provided near the meandering correction guides on the upstream side thereof. With the above configuration, operation effects shown below can be achieved:
(1) Even if a nipping force of a conveyance roller pair downstream of meandering correction guides is set higher, a meandering connection can be made with precision. Thus, conveyance precision and meandering correction precision of roll paper can be achieved at the same time.
(2) The meandering correction guides can be brought into contact with sheet edges with precision. Thus, a precise meandering correction can be made without causing sheet buckling, crimps, and wrinkles.
(3) A print area, the conveyance roller pair, and the meandering correction guide pair are arranged substantially in one plane and thus, conveyance is less likely to be subject to stiffness of a sheet. Thus, it is relatively easy to control the sheet with precision. Consequently, excellent printing precision can be ensured.
(4) Meandering correction guides are provided also downstream of the print area so that excellent meandering correction precision can be maintained even if the print area is wide by guiding the sheet upstream and downstream of the print area.
(5) Excellent cutting precision can be ensured by arranging meandering correction guides upstream of a cutter unit. As a result, an excellent quality of a printed product can be maintained.
With the operation effects (1) to (5) described above, conveyance precision and meandering correction precision of sheet conveyance can be achieved at the same time at a high level so that a printing apparatus at a high level of printing quality can be provided.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all modifications, equivalent structures, and functions.
This application claims priority from Japanese Patent Applications No. 2010-104295 filed Apr. 28, 2010 and No. 2010-108789 filed May 10, 2010, which are hereby incorporated by reference herein in their entirety.
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