Performing marginless printing based on image data

Marginless printing is performed by using a printhead which ejects ink. Information on an inclination of a sheet to be conveyed is obtained, and in performing the marginless printing at a leading end of the sheet, an image region with respect to which ink is discarded to an outside of the sheet is set based on the obtained information. Further, a platen which supports the sheet by sucking in a manner facing the printhead which ejects the ink is provided and control is performed such that in performing printing sequentially from the leading end to a trailing end of the sheet, suction force of the platen is decreased upon approach of a portion to be printed to the trailing end of the sheet.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a technique of inkjet printing which can perform marginless printing.

Description of the Related Art

In marginless printing performed by an inkjet printing apparatus, a printing operation is performed based on image data corresponding to a region which is larger in size than a sheet such that a border does not remain on the sheet even though errors in sheet conveyance or the like occur. Japanese Patent Laid-Open No. 2006-021475 discloses a printing apparatus which can perform marginless printing.

In sheet conveyance, a phenomenon called skewing occasionally occurs, in which a sheet is conveyed with an inclination relative to an advance direction. In Japanese Patent Laid-Open No. 2006-021475, since the influence of the occurrence of skewing in performing marginless printing is not taken into consideration, if skewing occurs, the quantity of ink discarded to the outside of the sheet increases, and as a result, unnecessary ink consumption increases in some cases. Further, in Japanese Patent Laid-Open No. 2006-021475, a sheet is sucked by a suction platen. In this configuration, in performing marginless printing at a trailing end of the sheet, atomized ink mist is occasionally sucked into a gap between the sheet and a suction unit, resulting in adhesion of the ink mist to the reverse of the sheet particularly at the trailing end thereof to smear the sheet.

SUMMARY OF THE INVENTION

An object of the present invention is to suppress an increase in unnecessary ink consumption even though skewing occurs on a sheet in performing marginless printing. Another object of the present invention is to reduce the quantity of ink mist which adheres to the reverse of the sheet in a printing apparatus having a suction platen.

One aspect of the present invention is a printing method for performing marginless printing by using a printhead which ejects ink, the method including the steps of: obtaining information on an inclination of a sheet to be conveyed; and setting, in performing the marginless printing at a leading end of the sheet, based on the obtained information, an image region with respect to which the ink is discarded to the outside of the sheet.

DESCRIPTION OF THE EMBODIMENTS

With reference to the drawings, an embodiment according to the present invention will be described in detail.

FIG. 1is a schematic perspective view showing the configuration of a printing apparatus1.FIG. 2is a schematic cross-sectional view showing the configuration of the printing apparatus1. The printing apparatus1is an inkjet printer which ejects ink from an ejection port, and is a printer of a serial type which can perform marginless printing in which ink is ejected to a sheet up to its border. Here, an explanation will be given of an apparatus having a printing function only, but the present invention is applicable to an apparatus having a copying function, a facsimile function, and the like.

The printing apparatus1has a feeder40and prints an image or the like on a sheet fed from the feeder40. The feeder40has a feed tray5and a feed roller6. The feed roller6contacts the sheet stacked on the feed tray5and rotates to unroll the sheet one by one from the feeder40and the sheet is fed to the printing apparatus1. The printing apparatus1includes also a printhead3, a carriage4, a conveyance roller7, a pinch roller8, a platen9, discharge rollers10, a pulley11, a discharge tray12, and a tube pump15.

The sheet fed from the feeder40is held by a conveyance roller pair of the conveyance roller7and the pinch roller8and is conveyed, by their rotation, downstream in a sheet conveyance direction (a y direction shown in the drawings) to move to a space between the printhead3and the platen9. On an ejection port forming surface facing in a gravity direction (a z direction shown in the drawings) of the printhead3, a plurality of ejection ports are formed. The printhead3is mounted on the carriage4. The carriage4is supported by a carriage guide shaft41and a carriage rail42which extend in a direction (an x direction shown in the drawings) transverse to the conveyance direction, and is capable of making a reciprocating motion in the x direction. The platen9is disposed at a position facing the ejection port forming surface of the printhead3and supports the sheet from the reverse of the sheet facing the ejection port forming surface. A duct27and a negative pressure generation mechanism43are disposed in the z direction downward of the position of the platen9. The x direction is a widthwise direction of the sheet to be conveyed as well as a moving direction of the carriage4and the y direction is the sheet conveyance direction.

The sheet conveyed, by the conveyance roller pair, downstream in the y direction is held by a discharge roller pair of the discharge roller10and the pulley11and is discharged, by their rotation, toward the discharge tray12from the inside of the printing apparatus1. An intermittent feeding operation (sub scanning) of the sheet performed by the roller pairs and an ejecting operation of ejecting ink from the ejection port of the printhead3together with a scanning movement (main-scanning) of the carriage4are repeated to perform serial printing an image in a serial printing system.

The feeder40, carriage guide shaft41, carriage rail42, platen9, and the like are fixed to a chassis28.

As shown inFIG. 2, an end detection lever48and a lever detection sensor49are disposed between the feed roller6and the conveyance roller pair. The end detection lever48is disposed at a position where the end detection lever48contacts the sheet conveyed from the feed roller6to the conveyance roller pair and is configured such that its postures are different in states in which the end detection lever48contacts and does not contact the sheet. The lever detection sensor49is a reflective light sensor and constitutes a detection unit for detecting that the leading end or the trailing end of the sheet to be conveyed reaches a detection position, based on a change in the posture of the end detection lever48caused by the passage of the sheet.

FIG. 3is a perspective view showing the peripheral structure of the carriage4. It should be noted that the view shows a state in which the printhead3is removed. On one of side surfaces in the x direction of the carriage4, a carriage sensor44(a sheet end detection sensor) is mounted. The carriage sensor44is a sensor constituting a detection unit for detecting an end of a sheet2. The carriage sensor44is a reflective light sensor having a light emitting unit and a light receiving unit, in which the light emitting unit emits light in the z direction, light reflected from the platen9or the sheet2is received at the light receiving unit, and the received light is converted into an electric signal to be output.

The carriage sensor44is disposed further downstream in the y direction of a most downstream ejection port in the y direction. The printhead3and the carriage sensor44are in a positional relation in which in single pass printing, results of detection of a side end obtained from the carriage sensor44in one movement of the carriage4can be reflected to the ejecting operation of the printhead3along with the next movement of the carriage4. The detection of a left and a right end will be described later with reference toFIG. 14.

Here, an explanation will be given of printing an image in a serial printing system by the single pass printing. Printing of an image is not limited to this, but may be performed by multiple pass printing in which an image is completed in a predetermined region by an ink ejecting operation of the printhead3along with the movement of the carriage4multiple times. In this case, the timing of reflecting the results of detection of the left and the right ends obtained by the carriage sensor44are adjusted as appropriate.

The carriage4is driven by a carriage drive motor104. The carriage4has a flexible cable45connected thereto. A drive signal to the printhead mounted on the carriage4is transmitted from a CPU101, which will be described later with reference toFIG. 11, through the flexible cable45to the printhead3. Further, a detection signal from the carriage sensor44is input via the flexible cable45to the CPU101.

With reference toFIG. 4toFIG. 8, the platen9will be described.FIG. 4is a perspective view showing the platen9.FIG. 5is a perspective view showing the platen9before an absorbing member35shown inFIG. 4is disposed thereon.FIG. 6is an enlarged perspective view of a portion VI enclosed with a dotted line shown inFIG. 5.FIG. 7is a cross-sectional view taken along a dotted line VII-VII shown inFIG. 4.FIG. 8is a cross-sectional view taken along a dotted VIII-VIII shown inFIG. 4.

As shown inFIG. 4toFIG. 6, the platen9is provided with an upstream supporting portion32and a downstream supporting portion33at portions upstream and downstream in the y direction thereof, respectively. At a position between the upstream supporting portion32and the downstream supporting portion33, supporting portions14are provided. These supporting portions support the sheet from the reverse of the sheet. The upstream supporting portion32guides the sheet conveyed by the conveyance roller pair to the supporting portion14. The downstream supporting portion33guides the sheet conveyed by the conveyance roller pair to the discharge roller pair. As shown inFIG. 6, the supporting portion14has a supporting surface13and a recess17. The upstream supporting portion32and the downstream supporting portion33are ribs provided such that they contact the sheet at the same height (position in the z direction) as that of the supporting surface13and the plurality of upstream supporting portions32and the plurality of downstream supporting portions33are provided. The supporting portion14is in a rectangular shape and its outer periphery forms the supporting surface13having a predetermined width and the inside portion of the supporting portion14forms the recess17which is more deeply recessed than the supporting surface13. Further, as shown inFIG. 4toFIG. 6andFIG. 8, an end in the y direction upstream of the supporting portion14is inclined upward in the z direction from the upstream side toward the downstream side in the y direction and the sheet can be smoothly conveyed downstream in the y direction along the inclination. As shown inFIG. 4andFIG. 5, the supporting portions14in a plurality of types in different sizes are disposed. Most of the recesses17of the supporting portions14are provided with suction holes18. Further, the recess17in a relatively large size of the supporting portion14is provided with a rib extending in the y direction and being positioned at the same height as that of the supporting surface13for preventing the sheet from denting at the recess17, and the rib also supports the sheet as the supporting surface13.

As shown inFIG. 5toFIG. 8, in the surroundings of the supporting portion14, ink discarding grooves31(ink receivers) are provided adjacent to the supporting portion. As shown inFIG. 8, each of the grooves31is defined by a bottom31awhich is at a lower position than the supporting surface13and side walls31band is formed in a shape capable of temporarily storing ink therein. The groove31receives ink ejected to the outside of the sheet in performing the marginless printing or ejected by preliminary ejection. The size and arrangement of the supporting portion14and the arrangement of the grooves31are determined such that the grooves31are arranged at ends of the sheet in any size to be actually used among sheets in various sizes assumed to be used.

As shown inFIGS. 4, 7, and 8, the absorbing member35is disposed so as to cover the grooves31. Ink which is not applied to the sheet is received, through the absorbing member35, at the groove31which is positioned in the z direction downward of the absorbing member35. In order to prevent the ink applied to the absorbing member35from splashing and adhering to the reverse of the sheet or the like, it is preferable to use, as the absorbing member35, a member capable of suppressing the splash upon the adhesion of ink. Here, a member made of expanded urethane is used as the absorbing member35. The absorbing member35is supported by the side walls31band the bottom31aof the groove31. Further, the absorbing member35is locked by lock claws38shown inFIG. 4. As shown inFIG. 4, the lock claws38are provided at portions in the y direction upstream and downstream of the platen9. The ink which has permeated the absorbing member35and been received at the groove31flows into a channel31cwhich is a portion of the groove31. The channel31cincludes an upstream channel31c1provided upstream in the y direction and extending in the x direction, a downstream channel31c3provided downstream in the y direction and extending in the x direction, and a center channel31c2provided at a center portion in the x direction and extending in the y direction. The channels31c1and31c3are provided so as to communication with the groove31extending in the y direction and have a relatively large area. The center channel31c2is connected to the upstream channel31c1and the downstream channel31c3and allows the upstream channel31c1and the downstream channel31c3to communicate with each other.

As shown inFIG. 7, a bottom surface of the downstream channel31c3is inclined downward in the z direction from both ends in the x direction to the center portion and a downstream accumulation portion31d3is provided at the most downward portion of the bottom surface of the downstream channel31c3. The upstream channel31c1is in a form similar to the downstream channel31c3and an upstream accumulation portion31d1is provided at its most downward portion. As shown inFIG. 8, the downstream accumulation portion31d3is positioned in the z direction downward of the upstream accumulation portion31d1. The center channel31c2allows the upstream channel31c1and the downstream channel31c3to communicate with each other so as to flow the ink accumulated in the upstream accumulation portion31d1toward the downstream accumulation portion31d3. With this configuration, the ink received at the groove31through the absorbing member35passes through the channel to be accumulated in the downstream accumulation portion31d3. The bottom surface of the channel is inclined so as to flow the ink along the inclination. In a case of accelerating the ink flow, grooves or the like may be provided along the inclination of the inclined bottom surface.

As shown inFIGS. 5, 7, and 8, the platen9is provided with an outer peripheral wall20at its outer periphery. The outer peripheral wall20is provided with a discharge port30. As shown inFIG. 8, the discharge port30communicates with the downstream accumulation portion31d3. The ink received at the groove31through the absorbing member35passes through the channels to be accumulated in the downstream accumulation portion31d3and is discharged through the discharge port30to the outside of the platen9.

FIG. 9is a cross-sectional view showing the peripheral structure of the duct27and an enlarged cross-sectional view showing a portion of the cross section shown inFIG. 2. As shown inFIG. 2andFIG. 9, the duct27is disposed between the platen9and the negative pressure generation mechanism43. The duct27is formed by a cover member23and a base member24. The cover member23and the base member24are provided with a first opening34and a second opening36, respectively. The base member24is disposed on the negative pressure generation mechanism43so as to allow the second opening36and a suction port37of the negative pressure generation mechanism43to communicate with each other and the cover member23is disposed on the base member24, thereby forming the duct27by the base member24and the cover member23to forma second negative pressure chamber25inside the duct27. With the engagement of the first opening34on the upper surface of the cover member23with the bottom surface of the outer peripheral wall20of the platen9, a first negative pressure chamber22is formed in the inner space which is in communication with the suction holes18of the platen9. It should be noted that the base member24is fixed to the chassis28shown inFIG. 1

The engagement portion of the first opening34of the cover member23with the bottom surface of the outer peripheral wall20and an engagement portion of the second opening36of the base member24with the suction port37of the negative pressure generation mechanism43each have a seal member26thereon to prevent leakage of air. It is preferable that the seal member26should be formed of a soft member that has high sealability such that other members such as the platen9are not deformed by the repulsive force at the time of compression. Here, an expanded rubber member made of ethylene propylene diene rubber (EPDM) is used as the seal member26.

As explained with reference toFIG. 5and the like, the discharge port30is provided on the outer peripheral wall20on the side surface in the y direction downstream of the platen9. Therefore, the duct27can be provided in a relatively wide space in the z direction downward of the platen9and the space in the second negative pressure chamber25in the duct27can be relatively wide, thereby enabling stabilization, in the second negative pressure chamber25, of the negative pressure generated by the negative pressure generation mechanism43.

Further, as shown inFIG. 9, the negative pressure generation mechanism43has a suction fan19. The negative pressure generation mechanism43rotates the suction fan19to suck air from a gap between the reverse of the sheet on the platen9and the recess17or the like and bring the sheet into tight contact with the supporting surface13of the supporting portion14to support the sheet. Here, a sirocco fan is used for the suction fan19. Suction force of the suction fan19can be changed and by control of the CPU101, which will be described later with reference toFIG. 11, the suction force of the suction fan19is adjusted according to the type of sheet, the state of a sheet, environmental conditions, and the like.

FIG. 10is a perspective view showing the tube pump15. As shown inFIG. 10, the tube pump15includes a tube16, a pump case21, a roller29, and a roller holder39. The discharge port30of the platen9is connected to a suction port at an end of the tube16and a waste ink tank (not shown) is connected to a discharge port at the other end of the tube16. The roller29is rotatably mounted on the roller holder39. The roller holder39rotates by a drive force transmitted from a pump drive motor107, which will be described later with reference toFIG. 11, via a gear train (not shown). The tube pump15is driven by the pump drive motor107, which squeezes the tube16while being pressed against an inner diameter surface of the pump case21by the roller29, thereby generating a negative pressure inside the tube16to suck the ink to discharge the ink through the discharge port30. Then, the ink accumulated in the accumulation portion31d3is discharged, through the discharge port30and the tube pump15, to the waste ink tank.

The timing of the tube pump15to be driven, that is, the timing of ink discharge by the tube pump15is set, for example, in a case where the quantity of the ink discharged to the absorbing member35exceeds a predetermined threshold. In this case, backflow of the ink to the absorbing member35or the like, which occurs in a case where the quantity of the ink accumulated in the accumulation portion31d3exceeds the accumulation capacity of the accumulation portion31d3, and adhesion of dried ink to the accumulation portion or the channels can be prevented. Further, the timing of ink discharge may be set such that ink is discharged at power-off of the printing apparatus1, after a predetermined time has elapsed since the previous discharge, upon receipt of an instruction from a user, or the like.

FIG. 11is a block diagram showing the configuration of a control system of the printing apparatus1. A head drive circuit102, a motor drive circuit103, and a sensor signal processing circuit108are connected to the CPU101(an obtaining unit, a control unit). The CPU101controls the overall operation of the printing apparatus1. It should be noted that the operation of the printing apparatus1may be controlled by an external control device which is not installed in the printing apparatus1. The head drive circuit102is a circuit to drive a printing element which is an ejection energy generation element (such as a heater and a piezoelectric element) of the printhead3. The CPU101controls, via the head drive circuit102, the ink ejecting operation of the printhead3. The motor drive circuit103is a circuit to drive the carriage drive motor104, a conveyance roller drive motor105, a feed roller drive motor106, the pump drive motor107, and the suction fan19. The CPU101is a control unit installed in the printing apparatus and is connected, via an interface, to a host computer (an external control unit) connected to the printing apparatus.

The sensor signal processing circuit108is connected to the carriage sensor44and the lever detection sensor49. The CPU101controls, via the sensor signal processing circuit108, turning on and off of the power to the carriage sensor44and the lever detection sensor49. Signals from the carriage sensor44and the lever detection sensor49are input to the sensor signal processing circuit108to be processed. The processed information is output from the sensor signal processing circuit108to the CPU101. The CPU101obtains, based on the information output from the sensor signal processing circuit108, the position and skewing (an inclination relative to an advance direction) of the sheet2and according to the position and skewing, the CPU101controls processing with respect to the leading end of the sheet in the printing operation. The description will be given in detail later with reference toFIG. 12or the like. It should be noted that the leading end refers to an end positioned in the y direction downstream of the sheet, a left and a right end each refers to each of both ends in the x direction of the sheet, and the trailing end refers to an end positioned in the y direction upstream of the sheet.

With reference toFIG. 12toFIG. 15, a description will be given of processing with respect to the leading end, left and right side ends, and trailing end of the sheet in the marginless printing operation.FIG. 12is a flowchart for explaining a flow of the marginless printing operation,FIGS. 13A and 13Bare views for explaining the position of the sheet in each of operations,FIG. 14is a schematic view for explaining processing with respect to the leading end and left side and right side ends of the sheet, andFIG. 15is a schematic view for explaining processing with respect to the trailing end of the sheet.

A description will be given of processing performed after a marginless printing start instruction is input to the CPU101. In the printing apparatus according to the present embodiment, marginless printing and border printing can be selectively performed and it is determined, in advance, whether marginless printing processing is performed. In a case of performing the marginless printing, a sequence shown inFIG. 12is performed. It should be noted that the sequence control is performed by the CPU101installed in the printing apparatus, but the same sequence control may be performed by a host computer connected to the printing apparatus.

As shown inFIG. 12, upon the input of the marginless printing start instruction from a user to the CPU101, the CPU101starts the marginless printing processing (S201). The printing start instruction includes information on the type (the size as well) of sheet, but the information on the type of sheet may be detected by the detection unit such as a sensor to be input to the CPU101. Upon receipt of the marginless printing instruction, the CPU101generates image data (data for driving the head) for the marginless printing corresponding to a region which is larger in size than the sheet such that a border does not remain on the sheet even though errors or the like in sheet conveyance occur.

The CPU101actuates, via the motor drive circuit103, the suction fan19to prepare to suck the sheet2to the platen9for supporting the sheet2(S202). The CPU101defines the width (the length in the x direction) of the sheet based on the information on the type of sheet (S203) and moves the carriage4to a position inward of an end portion of the sheet2by a predetermined amount. To be specific, the CPU101moves the carriage4such that the carriage4is positioned inward by a distance α from a position where a corner E of the sheet2shown inFIG. 14is presumably positioned (S204). In a case where the carriage4is moved to the position where the corner E of the sheet2is presumably positioned and the corner E of the sheet2is detected by the carriage sensor44, if skewing or the like occurs on the sheet2, the corner E of the sheet2may not be detected in some cases. Therefore, even though skewing occurs, a position where the sheet2is presumably positioned is set to be the predetermined position inward by the distance α from the position where the corner E is presumably positioned and the carriage sensor44is positioned such that a detection position of the carriage sensor44is set to this predetermined position. The CPU101moves the carriage4to a desired position based on detection results obtained from a linear encoder for detecting the position of the carriage4and stops the carriage4. It should be noted that the corner E is selected as a more downstream apex of the sheet and in a case where the inclination of the sheet is in the reverse direction, a corner F is selected and a similar processing is performed.

The CPU101drives the feed roller6by the feed roller drive motor106to feed the sheet2to the inside of the printing apparatus1(S205). Further, the conveyance roller7is driven by the conveyance roller drive motor105to convey the fed sheet2downstream in the y direction by the conveyance roller pair (S205). Upon arrival of the sheet2at a detectable range of the carriage sensor44, the leading end of the sheet2is detected by the carriage sensor44(S206), and then the detection result is sent to the CPU101. The position information on a position P of the detected leading end is stored in a predetermined memory of the CPU101. Upon detection of the leading end of the sheet2by the carriage sensor44, the CPU101stops conveying the sheet2(S207).

Next, the CPU101moves the carriage4such that the detection position of the carriage sensor44is set inward by the distance α from the corner F on the opposite side of the corner E shown inFIG. 14and then stops the carriage4(S208). At the same time, the CPU101conveys the sheet2so as to return the sheet2upstream in the y direction (S208) and sets the leading end of the sheet2at a position in the y direction upstream of the position of the carriage sensor44. It should be noted that the processing is not limited to the aspect in which the movement of the carriage4and the return of the sheet2are simultaneously performed, but may be performed such that one of the operations is performed prior to the other.

After returning the sheet2upstream in the y direction until the leading end of the sheet2is positioned in the y direction upstream of the position of the carriage sensor44, the CPU101again conveys the sheet2downstream in the y direction (S209). Similarly to the detection of the position P, upon detection of the leading end of the sheet2by the carriage sensor44(S210), position information on a position Q of the detected leading end is stored in a predetermined memory. Upon detection of the leading end of the sheet2by the carriage sensor44, the CPU101stops conveying the sheet2.

Subsequently, based on the position information on the positions P and Q, the CPU101virtually defines a line including the positions P and Q as a leading end border FL of the sheet2(S211). If there is skewing in the sheet conveyance, the leading end border FL line is inclined relative to the x direction and if there is no skewing, the line is a straight line parallel to the x direction. The CPU101calculates the inclination of the leading end border FL relative to the direction (the x direction) in which the carriage4moves, and obtains the positions (relative positions) of the two apexes, the corners E and F, of the leading end of the sheet from the width of the sheet to be used and the distance α. Then, it is determined which of the two corners is a more downstream corner of the sheet. In the example ofFIG. 14, the corner E is selected, but in a case where the sheet is inclined in a different direction, the corner F is selected. In a case where there is no inclination, any of the corners may be selected. Further, the CPU101obtains a mean value of the positions P and Q to calculate a position, in the y direction, of a center C (a reference position of a center reference) of the leading end border of the sheet2(S211). It should be noted that the processing is not limited to the mode in which the leading end of the sheet is detected at two positions, but the information for calculation may be obtained by performing detection at three positions.

By using these calculation results, the CPU101determines image data for driving the head for use in printing at the leading end portion of the sheet2(S212). Data obtained by excluding, from data corresponding to the region in the y direction downstream of the image data for the marginless printing generated according to the size of the sheet, data corresponding to a region where the sheet is not positioned, is determined to be data for use in printing at the leading end portion. In this case, considering detection errors by the carriage sensor44, errors in the conveyance by the conveyance roller7, and the like, data to be used is determined so as to prevent a border from remaining on the leading end portion of the sheet2.

More specifically, as shown inFIG. 14, image data which is supposed to be printed with respect to the region in the y direction downstream of a line DL which is offset by a predetermined distance β outward and parallel to the calculated leading end border FL is determined to be image data to be discarded47. That is, data corresponding to the region in the y direction downstream of the position away from the leading end border FL by a predetermined amount is determined to be the image data to be discarded. The image data to be discarded47is discarded and data excluding the image data to be discarded47from the image data46is set to be image data for use in printing. It should be noted that inFIG. 14, the line DL is shown as a straight line, but is not necessarily a straight line. The line DL may be a stepwise line close to a straight line depending on a resolution and processing capability of the CPU101.

In this manner, in performing the marginless printing at the leading end of the sheet, based on the information on the inclination of the sheet, an image region with respect to which ink is discarded to the outside of the sheet is set. If viewed from a different perspective, an image region with respect to which the ink is no longer discarded to the outside of the leading end of the sheet is set. Here, the information on the inclination of the sheet includes relative positions of the two corners E and F of the leading end of the sheet. Further, the more downstream corner (the corner E in the example ofFIG. 14) of the sheet is important in setting the image region with respect to which the ink is discarded.

The CPU101conveys the sheet2such that the sheet2is located at a position (a printing start position) on the supporting surface13of the platen9(S213). A rotary encoder is mounted on the conveyance roller drive motor105and the CPU101confirms, based on the detection result of the rotary encoder, the amount of the sheet2to be conveyed to adjust the amount.

FIG. 13Ashows the position (the printing start position) of the sheet2at printing operation start timing andFIG. 13Bshows a position (a print completion position) of the sheet2at printing operation completion timing. In the state shown inFIG. 13A, the leading end border of the sheet2is positioned in the z direction above the groove31downstream in the y direction and in the y direction upstream of a most downstream ejection port3d. An end positioned most downstream in the y direction is set to be a reference and this end is positioned in the z direction above the groove31downstream in the y direction and in the y direction upstream of the most downstream ejection port3d. Upon start of the ejecting operation in this state, since all portions at the leading end border of the sheet2are positioned in the y direction upstream of the most downstream ejection port3d, a border can be prevented from appearing on the leading end border of the sheet2. In this state, a portion which was not applied to the sheet of the ink ejected from the ejection port is received at the absorbing member35disposed downstream in the y direction and on both sides in the x direction outside of the sheet2.

After setting the sheet2at the printing start position, the printing operation is started (S214). The ink ejecting operation in which the ink is ejected from the printhead3along with the movement of the carriage4in the x direction is performed (S215). As described above, an image is printed on the sheet by the single pass printing in which image printing with respect to a predetermined region is completed by performing an ink ejecting operation along with one movement of the carriage4. Further, each time the carriage4is positioned at the end portion in the x direction, that is, each time the carriage sensor44is set at a position where a side end of the sheet2can be detected, the position of the side end of the sheet2is detected by the carriage sensor44(S216). Based on the detection results of left and right side ends obtained in one movement of the carriage4, image data for use in the ink ejecting operation along with the next movement of the carriage4is determined. Considering detection errors of the carriage sensor44and errors in the conveyance by the conveyance roller7, the image data for use in printing is determined such that a border does not remain on the side end portion of the sheet2. As shown inFIG. 14, image data up to lines (virtual lines) RL and LL which are offset by a predetermined distance γ outside and parallel to the detected side ends is set to be the image data for use in printing. The conveying operation for conveying the sheet2downstream in the y direction is performed (S217).

Each time the operation of conveying the sheet2is completed, the CPU101confirms the detection result of the lever detection sensor49to determine whether the timing of starting the printing at the trailing end portion of the sheet2has arrived (S218). The CPU101detects the trailing end of the sheet2by using the lever detection sensor49to determine, based on the detection results of the lever detection sensor49and the rotary encoder, whether the timing of starting the printing at the trailing end portion of the sheet2has arrived.

Since the ink is already applied to a region in the y direction downstream of the sheet, in performing printing at the trailing end portion, if the end portion is detected while the conveyance direction of the sheet is being changed, similarly to the detection of skewing at the leading end, the image may be smeared with wet ink. A method may be considered in which after the detection of the trailing end of the sheet2by the carriage sensor44, data corresponding to a region in the y direction upstream of the trailing end is deleted. However, in a case where there is skewing on the sheet2, if the data corresponding to the region in the y direction upstream of an end portion after the detection of the end portion positioned most downstream in the y direction, is deleted, a border of the image may remain on the trailing end of the sheet2depending on the amount of skewing. On the other hand, even though the data corresponding to the region upstream of an end portion is attempted to be deleted after the detection of the end portion positioned most upstream in the y direction, there may be a case where the amount of image data which is not yet used for printing is small. Furthermore, there may be a case in which data processing may be missed without stopping temporarily the printing operation in data processing, in which case, temporarily stopping the printing operation requires time until the completion of the printing.

In view of these circumstances, detection of skewing is not performed with respect to the trailing end of the sheet. Instead, the center of the trailing end is detected by using the end detection lever48and the lever detection sensor49, which are disposed at positions in the y direction upstream of the carriage sensor44and relatively far from the printhead3.

The end detection lever48is disposed at a position through which any centers of sheets in various sizes presumably pass, and contacts a center portion of the sheet2. That is, sheets in various widths are fed by a system called the center reference. The CPU101obtains the position of the center portion of the sheet2based on the detection results of the lever detection sensor49and the rotary encoder.

Moreover, with respect to the center portion of the sheet2, immediately before the ejecting operation performed at a region of a distance ε inward of the trailing end of the sheet2shown inFIG. 15, the CPU101decreases the suction force to reduce the amount of air to be sucked. The center portion of the sheet2is positioned inward by a predetermined amount in the y conveyance direction downstream of the trailing end of the sheet2and then immediately before the ejecting operation at the region including the center portion of the sheet2, the suction force is decreased. In such a manner, in performing printing sequentially from the leading end to the trailing end of the sheet, control is performed such that a portion to be printed approaches the trailing end of the sheet and then the suction force of the platen is decreased. As a result, the quantity of the ink mist flowing into the recess17from a slight gap between the reverse of the sheet2and the recess17can be reduced.

In this manner, in the configuration in which the sheet2is sucked to the platen9, even though processing of deleting data is not performed with respect to the trailing end, unlike the processing performed with respect to the leading end, adhesion of the ink mist to the reverse of the sheet2can be reduced. Since the ink is already applied to the sheet2in printing at the trailing end, even though the suction force of the suction fan19is decreased, it is unlikely that the sheet2floats to contact the ejection port forming surface3ashown inFIG. 13AandFIG. 13B. It should be noted that detection of skewing is not performed with respect to the trailing end, and thus it is preferable that the distance ε is set to be a value greater than the distance β or the distance γ. The distance ε is set to be, for example, from 1 mm to 10 mm.

Before the printing at the trailing end portion is started (NO in S218), the processing returns to S215. At the timing of starting printing at the trailing end portion (YES in S218), the CPU101controls the motor drive circuit103to decrease the driving rotational speed of the suction fan19from the previous speed (S219). This decreases the suction force of the suction fan19. The “decreasing the suction force” includes stopping the rotational operation of the suction fan19to decrease the suction force to zero. The driving rotational speed of the suction fan19is determined according to the type of sheet2, the type of ink to be applied to the sheet2, environmental conditions inside the printing apparatus1, and the like.

The CPU101determines whether the printing operation is completed or not (S220). The CPU101determines, based on whether image data to be printed still remains, whether the printing operation is completed or not. At the timing in which the most upstream end portion in the y direction of the trailing end of the sheet2reaches the print completion position shown inFIG. 13B, the printing operation for one sheet is completed. In the state shown inFIG. 13B, the most upstream trailing end in the y direction of the sheet2is positioned above the groove31upstream in the y direction and in the y direction downstream of a most upstream ejection port3c. In this state, since any portion of the trailing end of the sheet2is positioned in the y direction downstream of the most upstream ejection port3c, completing the ejecting operation in this state can prevent a border from appearing on the trailing end border of the sheet2. In a case where the printing operation is not yet completed, that is, image data to be printed still remains (NO in S220), the processing returns to S215. In a case where the printing operation is completed, that is, image data to be printed does not remain (YES in S220), the sheet2is discharged to the discharge tray12from the inside of the printing apparatus1(S221) and the marginless printing processing is completed (S222).

As described above, in performing the marginless printing at the leading end of the sheet, the image region with respect to which the ink is discarded to the outside of the sheet is set based on the information on the inclination of the sheet. Two positions at the leading end of the sheet are detected to define the leading end border of the sheet and data corresponding to the region outside the leading end border is discarded. That is, the image region with respect to which the ink is discarded to the outside of the sheet is set such that the ink is discarded up to the downstream parallel to and away, by the predetermined distance β, from a side of the leading end of the sheet and the ink is not discarded further downstream. Focusing on the further downstream corner of the sheet which is important, in applying the ink to the corner E of the sheet, the ink is discarded up to the downstream away from the corner E of the sheet by the predetermined distance β and the ink is not discarded further downstream.

In performing the marginless printing, even though skewing occurs on the sheet, the ink to be discarded to the outside of the sheet particularly at the leading end side of the sheet is suppressed to reduce the unnecessary consumption of ink. Further, as compared to a case in which data is not discarded, the quantity of the ink mist generated is reduced due to the reduction in the quantity of the ink to be ejected and adhesion of the ink mist to components of the printing apparatus or the reverse of the sheet is reduced.

Meanwhile, with respect to the trailing end portion of the sheet2, the suction force of the suction fan19is decreased starting from a predetermined position to reduce the quantity of air taken into the suction holes18, thereby reducing the quantity of the ink mist as well as the air taken into the suction holes18to enable the reduction in the quantity of the ink mist adhering to the reverse of the trailing end of the sheet2. In this manner, also in the configuration in which the suction fan19is used, the quantity of the ink mist adhering to the reverse of the sheet2can be reduced. With respect to the trailing end portion of the sheet2, by stopping the operation of the suction fan19in decreasing the suction force, the effect of reducing the quantity of the ink mist adhering to the reverse of the sheet2can be improved.

FIG. 16is a schematic view for explaining another example of processing with respect to the leading end of the sheet2. The left and right side ends and the trailing end are processed in the same manner as in the above processing.

Specifically, in S211ofFIG. 12, based on the detection results of the positions P and Q, the position of the corner E most downstream in the y direction is calculated. In S212, with respect to the image data46, a virtual line DL is set, which passes a region which is away, by a predetermined distance β outside in the downstream, from the position of the corner E, which is a downstream apex of the sheet, and parallel to the scanning direction (the x direction) of the carriage4. Then, data corresponding to the region in the y direction downstream of the virtual line DL is set to be the image data to be discarded47. The corner E is selected as the apex in the downstream of the inclination, and if the inclination of the sheet is in the reverse direction, the corner F is selected and a similar processing is performed. In this manner, data obtained by excluding, from the image data46, the image data to be discarded47is set to be the image data for use in printing at the leading end portion of the sheet2. That is, in applying the ink to the further downstream corner E of the sheet in the marginless printing, the image region with respect to which the ink is discarded to the outside of the sheet is set such that the ink is discarded up to the downstream away from the corner E of the sheet by the predetermined distance β and the ink is not discarded further downstream.

In the case shown inFIG. 16, as compared to the case explained with reference toFIG. 14, processing time in S212ofFIG. 12can be reduced. Also in the case shown inFIG. 16, if skewing occurs on the sheet2, data corresponding to the region outside the most downstream position in the y direction of the leading end of the sheet2is discarded, and thus the ink consumption for the corresponding region of the data can be suppressed. That is, in performing the marginless printing, even though skewing occurs on the sheet, the quantity of the ink to be discarded to the outside of the sheet at particularly the leading end side of the sheet is suppressed to reduce unnecessary ink consumption. The quantity of the ink mist adhering to each member of the printing apparatus1and the reverse of the sheet2can also be reduced.

This application claims the benefit of Japanese Patent Applications No. 2015-108004, filed May 27, 2015, No. 2015-108006, filed May 27, 2015 which are hereby incorporated by reference wherein in their entirety.