Recording apparatus and sheet processing method

An apparatus includes a guide unit configured to guide surfaces of a sheet, which is conveyed after passing through a recording unit, with respect to a vertical direction, the guide unit having an interval variable in the vertical direction, and a correction mechanism for correcting skew of the sheet, which is inserted into the guide unit, by pushing the sheet from both sides thereof in a sheet width direction. The interval of the guide unit in the vertical direction widens when the sheet is cut compared with that when correction is executed by the correction mechanism, and when the sheet is cut, conveyance of the sheet is temporarily stopped in a position of the cutter. In cutting, a loop of the sheet is formed on the guide unit the interval of which in the vertical direction has widened.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a recording apparatus for recording an image on a continuous sheet.

2. Description of the Related Art

In a recording apparatus having the function of executing recording on a continuous sheet to cut the sheet for each unit length, a technique to correct the skew of the sheet is important. For example, a recording apparatus discussed in Japanese Patent Application Laid-Open No. 2004-98327 includes a mechanism to detect an inclination by a sensor and execute skew correction by a skew roller. In a case in which the inclination of a sheet is large when the sheet is cut with the skew remaining uncorrected, the sheet may be cut on a skew to cut off the end of a recorded image. Thus, in this case, the sheet is not cut and discharged as it is.

In Japanese Patent Application Laid-Open No. 2004-98327, when the sheet is not cut and discharged, a user is later forced into cutting by hand. Thus, it is inconvenient. In particular, when a large quantity of different images is continuously recorded and discharged, if sheets different in length are mixed among cut sheets stacked on a discharge tray, this causes the user to be confused. Even if the user extracts only a sheet large in length to cut by hand, the order of images may be changed. If the order is significant, it becomes inconvenient.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, a recording apparatus includes a recording unit configured to record data on a sheet, a guide unit configured to guide, in a first direction, at least one surface of the sheet, wherein the sheet is conveyed to the guide unit from the recording unit, the guide unit having an interval variable in the first direction, a correction unit configured to correct skew of the sheet, which is received by the guide unit, by urging the sheet from at least one side thereof in a second direction which is perpendicular to the first direction, and a cutting unit configured to cut the sheet having undergone skew-correction by the correction unit, wherein the guide unit is configured such that the interval of the guide unit in the first direction is wider when the sheet is at a position to be cut by the cutting unit than that when skew correction is executed by the correction unit, the recording apparatus further comprising a control unit for temporarily stopping conveyance of the sheet when the sheet is at the position to be cut by the cutting unit.

According to another aspect of the present invention, a sheet processing method includes guiding, with a guide unit, at least one surface of a sheet in a first direction along a conveying path, correcting skew of the sheet, received by the guide unit, by urging the sheet from at least one side thereof in a second direction which is perpendicular to the first direction, setting an interval of the guide unit in the first direction to be wider when the sheet is at a cutting position than when skew correction is executed, and temporarily stopping conveyance of the sheet in a cutting position.

DESCRIPTION OF THE EMBODIMENTS

As an exemplary embodiment of the present invention, a printer of an inkjet method using a line type print head will be described as an example. In this description, “printer” is not limited to an apparatus for exclusive use specialized in a print function. “Printer” includes a multifunction peripheral combining the print function and the other functions, a manufacturing apparatus for forming an image and a pattern on the media, and the like.

FIG. 1illustrates the whole configuration of a printer using a sheet roll (continuous sheet longer than a length of a print unit is wound in a roll pattern). The whole apparatus includes a sheet roll unit1, a conveyance unit2, a head unit3, a print head4, a cutter unit5, a drying unit6, a speed absorption unit7, a control unit8, and an ink tank9. These are disposed in a casing of the apparatus. The control unit8contains a control section including a controller and various types of input-output (I/O) interfaces, and is responsible for various types of control of the whole apparatus.

The sheet roll unit1includes both of an upper stage sheet cassette11aand a lower stage sheet cassette11b. A user fits a sheet roll on a holder and inserts it into a printer main body from the front to fit it. A sheet pulled out from the upper stage sheet cassette11ais conveyed in a direction of arrow a inFIG. 1and a sheet pulled out from the lower stage sheet cassette11bis conveyed in a direction of arrow b inFIG. 1. The sheet from either unit also travels in a direction of arrow c inFIG. 1to reach the conveyance unit2. The conveyance unit2conveys the sheet in a direction of arrow d (horizontal direction) inFIG. 1in process of printing by a plurality of rotating rollers. Above the conveyance unit2, the head unit3is oppositely disposed. On the head unit3, the independent print head4for a plurality of colors (six colors) is retained along a conveyance direction of the sheet. In synchronization with conveyance of the sheet by the conveyance unit2, ink is discharged from the print head4to form an image on the sheet. The recording unit includes the conveyance unit2, the head unit3, and the print head4. The ink tank9independently stores ink of each color. The ink is supplied from the ink tank9to a sub tank provided corresponding to each color by a tube. The ink is supplied from the sub tank to each print head4by a tube. The control unit8includes a controller and various types of I/O interfaces, and is responsible for various types of control of the whole apparatus.

The sheet discharged from the conveyance unit2is conveyed in a direction of arrow e and inserted into the cutter unit5. In the cutter unit5, the sheet (sheet roll) is cut into a length of a predetermined print unit. The length of the predetermined print unit is different according to the size of an image to be printed. For example, in an L size photograph, the length in the conveyance direction is 135 mm. In an A4 size, the length in the conveyance direction will be 297 mm.

The drying unit6is a unit configured to heat the sheet passing through inside the unit in a direction of arrow g inFIG. 1with warm air in order to dry the sheet applied with ink in a short time. The sheet cut into a unit length passes through inside the drying unit6one by one, is discharged in a direction of arrow h inFIG. 1, and is stacked on a discharge tray. On a conveyance channel, between the cutter unit5and the drying unit6, the speed absorption unit7for absorbing a difference in conveyance speed of the front and the rear is provided. On the speed absorption unit7, the sheet is conveyed in a direction of arrow f inFIG. 1.

FIG. 2illustrates the configuration of the sheet roll unit1. In each of the upper stage sheet cassette11aand the lower stage sheet cassette11b, the sheet roll is loaded. Each cassette can be loaded with the sheet roll having various sheet widths. InFIG. 2, the upper stage sheet cassette11ais loaded with a sheet having a minimum width and the lower stage sheet cassette11bis loaded with a sheet having a maximum width. The sheet roll pulled out from either of the sheet cassettes is supplied to the conveyance unit2. A conveyance speed at this time is a speed A (e.g., 75 mm/sec.). This speed is equal to a speed A of the sheet that is conveyed by the conveyance unit2in process of printing operation.

FIG. 3illustrates the configuration of the conveyance unit2. The rotation driving force of a conveyance motor21is transmitted by a belt23and a conveyance roller24is rotated. The state of rotation (rotation angle) of the conveyance roller24is detected by a rotary encoder22. Based on output of detection by the rotary encoder22, the conveyance motor21is subjected to feedback control and also ink discharge timing for printing is controlled. The rotation driving force of the conveyance roller24is transmitted to a plurality of feed rollers25(in this example, seven) by a transmission mechanism of a belt26and a pulley27. All of the plurality of feed rollers25and the conveyance roller24are rotated at the same circumferential speed to convey the sheet10. A conveyance speed of the sheet10in process of print operation is a fixed speed A.

FIG. 4illustrates the configuration of the head unit3. On the print head4, heads for respective colors (six colors) are aligned along a direction of arrow d in printing. A lined head of each color may be seamlessly formed by a single nozzle chip. A divided nozzle chip may regularly be aligned in a line or a staggered array. In the present exemplary embodiment, a so-called full multi head is used in which nozzles are aligned in the range that the width of a maximum sheet to be used is covered. As an inkjet method for discharging ink from a nozzle, methods of using a heater element, a piezoelectric element, an electrostatic element, or a micro electromechanical systems (MEMS) element can be employed. Based on print data, ink is discharged from a nozzle of each head. The timing of discharge is determined by an output signal of the rotary encoder22. The present invention is not limited to a printer of the inkjet method but is applicable to various print methods such as a thermal printer (sublimation type, thermal transfer type, etc.) and a laser printer.

FIG. 5illustrates the configuration of the cutter unit5. In the cutter unit5, the sheet is conveyed in a direction of arrow e inFIG. 5. A conveyance speed when entering the cutter unit5is the same speed A as the conveyance speed in the conveyance unit2. A motor55is a driving source for conveying the sheet in the cutter unit5. Further, on the cutter unit5, a correction mechanism120for correcting the skew of the sheet10is provided. An upper guide plate111ais a member included in the correction mechanism120. The detail thereof will be described below.

FIG. 6illustrates the configuration of the drying unit6. The sheet is shifted while being interposed between a plurality of conveyance belts61and a plurality of rollers62. To the plurality of conveyance belts61, the rotation driving force of a motor65is transmitted. The state of rotation of the motor65is detected by a rotary encoder66and the motor65is subjected to feedback control. A print face which is applied with ink and needed to be dried is turned downward. Air heated by a heater64is circulated in a direction of arrow z inFIG. 6by a fan63to facilitate drying of the sheet to be conveyed in a direction of arrow g inFIG. 6at the speed A. By fast drying, the sheet easily causes a curvature. However, the sheet is interposed between the conveyance belt61and the roller62during drying, the curvature is suppressed.

The configuration and the operation of the correction mechanism120contained in the cutter unit5illustrated inFIG. 5will be described. The following operation sequence is executed based on a command from the control section of the control unit8.

FIG. 7illustrates the configuration of the correction mechanism120and is a top view of the sheet10as viewed from above.FIGS. 8A and 8Billustrate cross-sectional views of the correction mechanism120as viewed from the side. As a correction mechanism for correcting the skew of the sheet by pushing the sheet10from both sides thereof in a direction of the sheet width, a roller mechanism, which includes two reference guide rollers112and113and one movable guide roller114, is provided. Both of the reference guide rollers112and113are retained in a secured position so as to be freely rotated and brought into contact with one side of the sheet10in a width direction at two places. Thus, it is determined that the sheet turns toward a correct direction. On another side of the sheet10in a width direction, the movable guide roller114, which can be shifted in the width direction, is retained so as to be freely rotated. The movable guide roller can be shifted at a predetermined stroke in a direction of arrow i inFIG. 7. When the tip of the continuous long sheet10is inserted into the guide unit, before the tip of the sheet reaches a conveyance roller117, the movable guide roller114is shifted in the direction of arrow i. The sheet10is pushed on the side of the reference guide rollers112and113to position the sheet at three places. Thus, even if a skew is present, the sheet can be corrected toward a correct direction.

In the apparatus in the present exemplary embodiment, the width of the sheet10can correspond to various sizes. A sheet10ainFIG. 7is a sheet having a minimum width supplied from the upper stage sheet cassette11a, whereas a sheet10billustrated by a dashed line is a sheet having a maximum width supplied from the lower stage sheet cassette11b. In order to deal with a difference between the minimum width and the maximum width, the movable guide roller114has a shift stroke by a distance obtained by adding a margin of skew to a distance of the difference between the minimum width and the maximum width of a sheet that is assumed to be used. A position114cis a waiting position of the movable guide roller114. The movable guide roller114is shifted from the position114cto a position114bwith respect to the sheet10bhaving the maximum width. An interval between two positions114cand114bis a margin of skew. Further, the movable guide roller114is shifted from the position114cto a position114awith respect to the sheet10ahaving the minimum width. A distance between two positions114band114acorresponds to a difference between the minimum width and the maximum width of the sheet. Furthermore, when a sheet has an intermediate size between the minimum width and the maximum width, the movable guide roller114is shifted to an intermediate position between the position114aand the position114b. The control section performs control to shift the movable guide roller114to a suitable position within a stroke corresponding to the size of a sheet to be used.

Further, in order to guide the sheet10by pushing surfaces of the sheet10from above and below (with respect to a vertical direction), the upper guide plate111aand the lower guide plate111bare provided, and the guide unit is formed with both the guide plates111aand111b.FIG. 8Aillustrates the state of the guide unit when skew correction is executed. In order to prevent buckling (locally large bend and fold) of a sheet when the sheet is interposed from both sides in a width direction and pushed thereon, in the guide unit, the top and the bottom are narrowed to the utmost to form a conveyance channel. Furthermore, as illustrated inFIG. 8B, the upper guide plate111ais rotated about a support shaft115provided at the end on the downstream side. For this rotation, a driving force of a motor mechanism110, which is a driving source, is provided to the support shaft115. The lower guide plate111bdoes not move and is continuously secured. A position of the upper guide plate111ain the open state inFIG. 8Ais a first position and a position of the upper guide plate111ain the closed state inFIG. 8Bis a second position.

On the downstream side of the guide unit, the conveyance roller117and a cutter118are provided. The cutter118is an auto cutter mechanism such as a circle cutter, a guillotine cutter, or a rotary cutter, which automatically cuts a sheet by a vertical blade. On the side more upstream than the cutter118and the conveyance roller117, and also in the vicinity of the most downstream of the guide unit, a sensor119for detecting the tip of a sheet is provided. The sensor119also detects the cutting position of a sheet other than the tip of the sheet. The cutting position is a blank portion between images continuously formed by the recording unit. In the blank portion, a sheet is cut for each predetermined unit length corresponding to the size of an image.

In the above configuration, the sheet10is inserted into the guide unit at the speed A by the conveyance roller116on the side more upstream than the guide unit. When the sensor119has detected that the tip of the sheet is inserted into the guide unit, before the sheet reaches the conveyance roller117, the movable guide roller114is shifted to a suitable position corresponding to the size of a sheet to be used. Thus, the sheet is interposed from both sides in a width direction to provide a suitable pushing force. While the sheet is shifted, on the guide unit, as illustrated inFIG. 8A, while buckling is prevented with the sheet vertically narrowly guided, the sheet is securely subjected to skew correction. The sheet10the direction of which is rightly corrected is interposed and retained by the conveyance roller117, which rotates at the conveyance speed A, and then reaches the cutter118. At this time, since the cutting blade of the cutter118is in an open state as illustrated inFIG. 8A, the tip of the sheet travels further ahead.

The sensor119optically detects a cut mark or a predetermined blank formed between an image of a first sheet and an image of a second sheet to detect a cutting position of the sheet. A predetermined unit length is determined according to the size of an image. Thus, the cutting position can roughly be predicted. In a roughly predicted range, an accurate cutting position is detected by the sensor119. When the sensor119detects the cutting position of the sheet, the control section conveys the sheet10until the cutting position is located on the cutting blade of the cutter118and then temporarily stops only the conveyance roller117. Even if the conveyance roller117in the vicinity of the position of the cutter118is temporarily stopped, the conveyance roller116on the side more upstream than that continues rotation. The cutter118accurately cuts the sheet whose conveyance is temporarily stopped in the position of the cutter118.

Simultaneously when the conveyance roller117is stopped or slightly prior to the stop, the control section controls the motor mechanism110to rotate the upper guide plate111afrom the first position to the second position in a direction of arrow k inFIG. 8B. Thus, the interval of the guide unit in a vertical direction widens when the sheet is cut by the cutter118compared with that when correction is executed by the correction mechanism120. When the upper guide plate111areaches the second position, on the guide unit, a wedge-shaped space is formed in which the interval of the guide unit in a vertical direction widens on the upstream side along a direction to which the sheet is conveyed and gradually narrows with travel toward the downstream side. While the sheet is cut, the conveyance roller117is stopped but the conveyance roller116continues rotation. Thus, the sheet is fed from the upstream side to the guide unit with the downstream side interrupted and the idle portion of the sheet10forms a loop10cin the wedge-shaped space of the guide unit. Since the upper guide plate111aescapes to the second position, the guide unit becomes wide in interval to provide a sufficient space. Thus, formation of the loop10cis not obstructed.

When the sheet has been cut by the cutter118, the control section starts rotation of the conveyance roller117to restart conveyance of the sheet in the position of the cutter118. At this time, the conveyance roller117is set with a rotation speed so as to be conveyed at a speed B larger than the speed A (e.g., speed 1.5 to 2 times as high as the speed A). A cut sheet having one unit length cut as described above is discharged from the cutter unit5, passes through the speed absorption unit7, and is fed to the drying unit6.

The conveyance roller116continuously conveys the sheet at the fixed speed A. Thus, the loop10cof the sheet10is gradually dissipated by a difference in speed (B−A). Timing to dissipate the loop10cis determined based on the speed A, the speed B, a time required for the speed 0 to reach the speed B, a time required for the speed B to reach the speed A, and a time required for cutting by the cutter118(each speed or time is a determined fixed value). In timing to dissipate the loop10c, the control section performs control so that the conveyance roller117reduces a conveyance speed from the speed B to the speed A, thereby eliminating a difference in speed between the conveyance roller117and the conveyance roller116. Only when the tip of the sheet is inserted into the guide unit and the skew correction is executed, the upper guide plate111ais located in the first position to narrow the interval between the vertical guides. Thereafter, the upper guide plate111ais located in the second position. After the upper stage sheet cassette11aand the lower stage sheet cassette11bare switched, or after the sheet role is replaced, the tip of the sheet is inserted.

The cut sheet having one unit length cut as described above is discharged from the cutter unit5, passes through the speed absorption unit7, and is fed to the drying unit6.

The recording unit records a plurality of images for each unit length while conveying the sheet at the fixed speed A. Also in an image after the second sheet, when the cutting position is detected by the sensor119, similarly the sheet is cut for each predetermined unit length.

When the tip of the continuous sheet is inserted into the guide unit, a conveyance defect such as jamming can be reduced when the upper guide plate111aopens a large space in the second position. Thus, in an initial state, as illustrated inFIG. 9, the upper guide plate111amay be located in the second position. When the tip of the sheet is inserted, the position may be switched to the first position, then the movable guide roller114may be shifted, and the skew correction may also be executed. Even if the sheet10is inserted into the position10edeviating from the original position10d, the conveyance defect does not occur and reliability is improved.

According to the above-described present exemplary embodiment, the recording apparatus includes the guide unit the interval of which in a vertical direction (first direction) is variable and the correction mechanism for correcting the skew of the sheet with the sheet present on the guide unit interposed from both sides in a width direction of the sheet (second direction). Then, the interval of the guide unit in a vertical direction is controlled so as to widen when the sheet is cut by the cutter compared with that when the correction is executed by the correction mechanism and also when the sheet is cut by the cutter, conveyance of the sheet is controlled so as to be temporarily stopped in the position of the cutter. When the sheet is cut by the cutter, on the guide unit the interval of which in the vertical direction widens, the loop of the sheet is formed. This allows a highly reliable recording apparatus and sheet processing method capable of executing secure skew correction and cutting of a sheet to be realized.

Further, in a layout of the apparatus in the present exemplary embodiment, there are no places to unnaturally bend a sheet. Thus, the apparatus can deal with sheets having various types of stiffness and realizes a printer compatible with miniaturization of the apparatus and various types of sheets. Furthermore, as the arrangement in which the sheet roll unit1, the recording unit, and the drying unit6, each having a large volume, are stacked in a direction of gravity, a sheet is roughly circumferentially circulated in the apparatus in order of processing. Thus, a printer having a small installation area (footprint) is realized.

This application claims priority from Japanese Patent Application No. 2009-165788 filed Jul. 14, 2009, which is hereby incorporated by reference herein in its entirety.