Method of setting maintenance regions posterior to unavailable printing regions in duplex printer

When a plurality of images is printed on both the surfaces of a continuous sheet, an optimum scheduling is carried out including maintenance of a print head, thereby suppressing amount of consumption of a sheet as a whole. For such a purpose, acquiring information regarding on which of the first and second surfaces and where on the surface of the continuous sheet a unique portion exists, the unique portion is unsuitable for image printing that exists on the continuous sheet; and setting, based on the acquired information, a print unavailable region including the unique portion and a maintenance region posterior thereto on a specific sheet surface having the unique portion existing thereon, and another print unavailable region and a maintenance region posterior thereto on a reverse side of the specific sheet surface, the another print unavailable region being set so as to include a region corresponding to the maintenance region.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a technology for executing duplex printing of a plurality of images on a continuous sheet.

2. Description of the Related Art

A continuous sheet for printing may include a unique portion which is region composed of a part of the sheet whose characteristic differs from the rest of the sheet, the unique portions unintentionally created in the sheet manufacturing process. If the image is printed on such the region in which unique portion exists, the image cannot be obtained as a good product.

Japanese Patent Laid-Open No. 2011-240493 discloses a method for executing duplex printing on a continuous sheet including unique regions inappropriate for printing, wherein the printing is executed while avoiding the unique regions on the obverse surface and the reverse surface of a sheet in consideration of the unique regions on both the surfaces of the sheet. In this method, when the unique portion on the continuous sheet is detected during the printing on the first surface, a unavailable region is set in the print schedule for a first surface, and a unavailable region at the position corresponding to the unique portion on the first surface is also set in a second surface print schedule, thereby continuing the printing.

The apparatus described in Japanese Patent Laid-Open No. 2011-240493 is not one in which an optimization is done to the extent of a schedule of maintenance (head maintenance) for a preliminary ejection3and the like, which is necessary for ink jet printing, so that it is susceptible to improvement.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a technique capable of suppressing the amount of consumption of a sheet as a whole when printing an image on both the surfaces of a continuous sheet by carrying out an optimum scheduling including maintenance of a print head.

Accordingly, a feature of the present invention is a print control method for printing a plurality of images on a first surface and a second surface of a continuous sheet, the method comprising: acquiring information regarding on which of the first and second surfaces and where on the surface of the continuous sheet a unique portion exists, the unique portion is unsuitable for image printing that exists on the continuous sheet; and setting, based on the acquired information, a print unavailable region including the unique portion and a maintenance region posterior thereto on a specific sheet surface having the unique portion existing thereon, and another print unavailable region and a maintenance region posterior thereto on a reverse side of the specific sheet surface, the another print unavailable region being set so as to include a region corresponding to the maintenance region.

According to the present invention, when a plurality of images is sequentially printed on both the surfaces of a continuous sheet, an optimum scheduling is carried out including maintenance of a print head even if a unique portion exists on the sheet, thereby suppressing the amount of consumption of a sheet as a whole.

DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention will be described below with reference to drawings. A printing apparatus of the present invention uses a long, continuous sheet for printing (a continuous sheet longer than a length of a print unit (which is referred to as one page or a unit image) that is repeated in a conveyance direction), and is a high-speed line printer capable of both simplex printing and duplex printing. For example, such the printing apparatus is suited to fields in which a large quantity of sheets is printed, such as at a print lab.

In addition, in this specification, even if a plurality of small images, characters, or blanks, is included in a region of one print unit (one page), objects included in the region are collectively referred to as one unit image. More specifically, the unit image means one print unit (one page) in a case where a plurality of pages is sequentially printed on the continuous sheet. Instead of the unit image, simply an image may be used.

The present invention is widely applicable to a printing apparatus which uses ink and is required to be dried, such as a printer, a multifunction printer, a copying machine, a facsimile machine, manufacturing apparatus of various devices.

FIG. 1is a cross-sectional schematic diagram showing an internal structure of a printing apparatus to which the present embodiment is applicable. The printing apparatus of the present embodiment can print on both a first surface and a second surface of a sheet using a sheet wound in a roll shape, where the second surface is on the back side of the first surface. Roughly speaking, the inside of the printing apparatus provides each of the units, i.e., a sheet feeding unit1, a decurling unit2, a positional deviation correction unit3, a printing unit4, an inspection unit5, a cutter unit6, an information recording unit7, a drying unit8, a reversing unit9, a discharge conveyance unit10, a sorter unit11, a discharge unit12, and a control unit13.

The discharge unit12refers to the unit which includes the sorter unit11and performs discharge processing of the sheet after printed. The sheet is conveyed by a conveyance mechanism composed of pairs of rollers and belts along a sheet conveyance path indicated by solid lines in the figure, and then processed at each unit. In addition, at an arbitrary position on the sheet conveyance path, a side closer to the sheet feeding unit1is referred to as an “upstream” side and an opposite side is referred to as a “downstream” side.

The sheet feeding unit1is the unit for holding and feeding the continuous sheet wound in a roll shape. The sheet feeding unit1is structured to be able to accommodate two rolls R1and R2, and to alternatively draw and feed the sheet. In addition, the rolls that can be accommodated are not limited to two, but one or three or more rolls may be accommodated. Furthermore, the sheet is not limited to a roll shape type as long as it is a continuous sheet. Furthermore, the sheet is not limited to a sheet wound in a roll shape, as long as it is a continuous sheet. For example, the sheet may be used in which a continuous sheet having perforations for each unit length applied thereto is folded back at each perforation and stacked, and then accommodated in the sheet feeding unit1.

The continuous sheet used here is one having marks which are previously recorded in order that unique portions such as stains can be detected. The unique portions are regions that are unsuitable for printing an image as a final product. A mark sensor17is provided in the vicinity of an outlet of the sheet feeding unit1so as to detect marks applied on the continuous sheets that is fed from the sheet feeding unit1.

The decurling unit2is the unit which reduces a curl (warpage) of the sheet fed from the sheet feeding unit1. The decurling unit2uses two pinch rollers for one drive roller to pass the sheet therethrough while curving the sheet so as to give the sheet the curling in a direction opposite to the curling thereof, so that a decurling force operates to reduce the curling.

The positional deviation correction unit3is the unit which corrects a positional deviation (tilt with respect to the original traveling direction) of the sheet which has passed through the decurling unit2. The positional deviation of the sheet can be corrected by pressing an end portion of the sheet on a reference side against a guide member. A loop is formed on the sheet being conveyed in the positional deviation correction unit3. The printing unit4is a sheet processing unit that performs print processing on the sheet being conveyed by a print head14from above to form an image. More specifically, the printing unit4is a processing unit that performs predetermined processing on the sheet.

The printing unit4is also provided with a plurality of conveying rollers for conveying the sheet. The print head14is provided with a line type print head in which an inkjet nozzle array is formed over a range that covers the maximum width of the sheet that is expected to be used. The print head14has a plurality of print heads aligned in parallel along the conveying direction. In the present embodiment, it is provided seven print heads corresponding to seven colors of cyan (C), magenta (M), yellow (Y), light cyan (LC), light magenta (LM), grey (G), and black (K). In addition, the number of colors and the number of print heads are not limited to seven.

As the ink jet method, methods can be employed such as a method using a heating element, a method using a piezoelectric element, a method using an electrostatic element, and a method using an MEMS element. Each color ink is supplied from an ink tank to the print head14via each ink tube.

The inspection unit5is the unit which uses a scanner to optically read an inspection pattern and an image that the printing unit4has printed on the sheet, and inspects the nozzle state in the print head, the sheet conveying state, the image position and the like, thereby determining whether the image is correctly printed. The scanner has a CCD image sensor and a CMOS image sensor.

The cutter unit6is the unit which is provided with a mechanical cutter18for cutting the sheet after printed to a predetermined length. The cutter unit6is also provided with a cut mark sensor for optically detecting cut marks recorded on the sheet, and a plurality of conveying rollers for delivering the sheet to the next step. A waste box19is provided in the vicinity of the cutter unit6. The waste box19is for accommodating small sheet fragments which are produced by being cut with the cutter unit6and discharged as waste. The cutting unit6is provided with a separating mechanism that discharges the cut-off sheet to the waste box19or brings the cut sheets to the original conveying path.

The information recording unit7is the unit which records printing information (unique information), such as print serial numbers and dates, in nonprinting regions of the cut-off sheet. The printing information is recorded by printing characters and codes using an ink jet method, a thermal transfer method, and the like.

The drying unit8is the unit which heats the sheet undergone the printing at the printing unit4so as to dry the ink applied thereto in a short time. Inside of the drying unit8, hot air is applied to the sheet passing therethrough at least from the underside surface thereof to dry the surface on which ink is applied. In addition, the drying method is not limited to applying hot air, but may be the method for irradiating the sheet surface with electromagnetic waves (such as ultraviolet rays and infrared rays).

The sheet conveying path from the sheet feeding unit1to the drying unit8described above is referred to as a first path. The first path has a shape of making U-turn between the printing unit4and the drying unit8, and the cutter unit6is located halfway through the U-turn shape.

The reversing unit9is the unit which, in a case where the duplex printing is executed, temporarily rolls up the continuous sheet in which the printing on the obverse surface is completed, and turns over the obverse and reverse surfaces. The reversing unit9is provided midway of a path (loop path) (referred to as a second path) from the drying unit8to the printing unit4via the decurling unit2for supplying the sheet passed through the drying unit8to the printing unit4again. The reversing unit9is provided with a winding rotary body (drum) that rotates to roll up the sheet.

The continuous sheet, which has undergone the printing on the obverse surface and is not cut yet, is temporarily rolled up by the winding rotary body. When finishing the rolling up, the winding rotary body inversely rotates to deliver the rolled sheet in an inverse sequence to the rolling up. The sheet is fed to the decurling unit2, and then sent to the printing unit4. Since the obverse and reverse surfaces of the sheet are reversed, the printing can be executed on the reverse surface at the printing unit4. If the sheet feeding unit1is a first sheet feeding unit, the reversing unit9can be regarded as a second sheet feeding unit. More specific operation of duplex printing will be described below.

The discharge conveyance unit10is the unit which conveys the sheet that is cut at the cutter unit6and dried at the drying unit8to pass the sheet to the sorter unit11. The discharge conveyance unit10is provided in a path (referred to as a third path) separate from the second path in which the reversing unit9is provided. In order to selectively guide the sheet conveyed through the first path to one of the second or third path, a path switching mechanism having a movable flapper is provided at the branching point of the path (referred to as a “discharge branching position”).

The discharge unit12including the sorter unit11is provided by a side of the sheet feeding unit1and at the end of the third path. The sorter unit11is the unit for sorting the printed sheets by group, as necessary. The sorted sheets are discharged into a plurality of trays that the discharge unit12has. In this way, the third path has a layout which passes below the sheet feeding unit1and discharges the sheet to a side opposite to the printing unit4and the drying unit8across the sheet feeding unit1.

As described above, the first path includes the units sequentially provided from the sheet feeding unit1to the drying unit8. The path ahead of the drying unit8branches into the second path and the third path. The reversing unit9is provided midway of the second path, and the path ahead of the reversing unit9merges to the first path. The discharge unit12is provided at the end of the third path.

The control unit13is the unit responsible for controlling each of units in the entire printing apparatus. The control unit13has a CPU, a storage device, a controller provided with various control units, an external interface, and an operating unit15by which a user carries out the input and output. The operation of the printing apparatus is controlled based on instructions from a controller, or a host device16, such as a host computer, which is connected via the external interface connected to the controller.

FIG. 2is a block diagram showing the concept of the control unit13. The controller (a region surrounded by a broken line) included in the control unit13is composed of a CPU201, a ROM202, a RAM203, an HDD204, an image processing unit207, an engine control unit208, and an individual unit control unit209. The CPU (central processing unit)201integratively controls the operation of each of the units in the printing apparatus. The ROM202stores a program that the CPU201is to execute, and a fixed data required for various operations of the printing apparatus.

The RAM203is used as a work area for the CPU201, is used as a temporary storage area of a variety of received data, and stores various setting data. The HDD (hard disc)204can store and read out a program that the CPU201is to execute, printing data, and setting information required for various operations of the printing apparatus. The operating unit15is an input/output interface for a user, and includes an input unit such as hard keys and a touch panel, and an output unit such as a display and an audio generator for providing information.

Dedicated processing units are provided for the units to which a high-speed data processing is required. The image processing unit207carries out image processing of printing data handled by the printing apparatus. The color space (for example, YCbCr) of the input image data is converted to a standard RGB color space (for example, sRGB). Furthermore, a variety of image processing, such as resolution conversion, image analysis, image correction, etc., is carried out on the image data as necessary. The printing data acquired by the image processing is stored in the RAM203or the HDD204.

The engine control unit208carries out the drive control of the print head14of the printing unit4in accordance with the printing data based on the control commands received from the CPU201and the like. The engine control unit208also controls the conveyance mechanism of each of the units in the printing apparatus. The individual unit control unit209is a sub-controller for individually controlling each of the units, i.e., the sheet feeding unit1, the decurling unit2, the positional deviation correction unit3, the inspection unit5, the cutter unit6, the information recording unit7, the drying unit8, the reversing unit9, the discharge conveyance unit10, the sorter unit11, and the discharge unit12.

The individual unit control unit209controls the operation of each of the units based on the commands from the CPU201. An external interface205is an interface (I/F) for connecting the controller to the host device16, and is a local I/F or a network I/F. The components described above are connected via a system bus210.

The host device16is the device as being a supply source of image data so that the printing apparatus executes the printing. The host device16may be a general-use or dedicated computer, or may be dedicated image equipment, such as image capturing equipment having an image reader unit, a digital camera, or a photo-storage. In a case where the host device16is a computer, an OS, application software for generating image data, and printer driver for the printing apparatus are installed in the storage device included in the computer. In addition, all processing described above does not necessarily have to be achieved by software, but a part or all of them may be achieved by hardware.

Then, the basic operation at the time of printing will be described. In the printing operation, the operation in the simplex printing mode is different from that in the duplex printing mode, so that each operation will be described separately. First, in the simplex printing mode, the sheet is fed from the sheet feeding unit and processed at each of the decurling unit2and the positional deviation correcting unit3, followed by undergoing the printing on the obverse surface (first surface) at the printing unit4. Images having a predetermined unit length (unit images) in the conveying direction are printed in sequence on the long continuous sheet to form an alignment of a plurality of images on the sheet.

The printed sheet is conveyed through the inspection unit5to the cutting unit6where the sheet is cut into unit images. The information recording unit7records printing information on the reverse surface of the sheet that has been cut (the cut sheet) as required. Then, the cut sheet is conveyed to the drying unit8one by one, where it is dried. Then, the cut sheets are conveyed through the discharge conveyance unit10and sequentially discharged into the discharge unit12of the sorter unit11to be stacked there. On the other hand, the rest of the sheet that is left on the side of the printing unit4at the time of cutting the last unit image is sent back to the sheet feeding unit1, and is rolled up to the roll R1or R2. In this way, in the simplex printing, the sheet is processed through the first and third paths, but does not pass through the second path.

On the other hand, in the duplex printing mode, the obverse surface (first surface) printing sequence is executed, followed by the reverse surface (second surface) printing sequence. In the obverse surface printing sequence that is to be firstly executed, the operation of each of the units from the sheet feeding unit1to the inspection unit5is the same as the operation in the simplex printing described above. The sheet is not cut at the cutter unit6, but is conveyed to the drying unit8as being the continuous sheet. The ink on the obverse surface is dried at the drying unit8, and then the sheet is guided not to the path on the side of the discharge conveyance unit10(third path), but to the path on the side of the reversing unit9(second path).

In the second path, the sheet is rolled up by the winding rotary body of the reversing unit9that rotates in the forward direction (counterclockwise in figure). When all of the scheduled printing on the obverse surface at the printing unit4is completed, the cutter unit6cuts the continuous sheet at the trailing edge of the printing area of the continuous sheet. Relative to the cut position, the continuous sheet on the downstream side of the conveying direction (printed side) is completely rolled up to the trailing edge of the sheet (cut position) at the reversing unit9through the drying unit8.

On the other hand, simultaneously to the winding at the reversing unit9, the continuous sheet that is left on the upstream side of the conveying direction (the side of the printing unit4) from the cutting position is sent back to the sheet feeding unit1to roll up the sheet onto the roll R1or R2so that the leading edge (cutting position) of the sheet does not remain in the decurling unit2. The sending back (backfeeding) enables the sheet to be prevented from colliding with a sheet supplied again in the reverse surface printing sequence described below.

After the obverse surface printing sequence described above, the sequence is switched to the reverse surface printing sequence. The winding rotary body of the reversing unit9rotates in a direction opposite to that during rolling up (clockwise in figure). The edge of the rolled up sheet (the trailing edge of the sheet at the time of rolling up is the leading edge at the time of delivering) is fed to the decurling unit2along the path represented by a broken line in figure. The curling of the sheet applied at the winding rotary body is corrected at the decurling unit2.

More specifically, the decurling unit2is provided between the sheet feeding unit1and the printing unit4in the first path and between the reversing unit9and the printing unit4in the second path, so as to be provided as the unit for executing the decurling that is common to both paths. The sheet whose obverse and reverse surfaces have been reversed is conveyed through the positional deviation correction unit3to the printing unit4, where printing is executed on the reverse surface of the sheet. The printed sheet is conveyed through the inspection unit5and is cut at the cutter unit6for each predetermined unit length set in advance.

The printing is applied to both surfaces of the cut sheets, so that the information is not recorded at the information recording unit7. The cut sheets are conveyed one by one to the drying unit8, and sequentially discharged and stacked in the discharge unit12of the sorter unit11through the conveying unit10. In this way, in the duplex printing, the sheet passes through in sequence the first path, the second path, and the third path in order to be processed.

Then, a unique portion existing in the continuous sheet will be described in detail. The unique portion refers to a region which is a part of the continuous sheet having the feature different from that of the rest of the sheet, i.e., the region which includes stains, bores, flaws, connecting portions between the sheets, folds, tears, admixture of foreign matters, discoloration, uneven thickness, impurities, and the like.

A mark for identifying the unique portion is the mark which is recorded within the predetermined range and anterior and posterior thereto to the unique portion on the sheet taking the deviation into consideration, and refers to the existence of the unique portion at the marked position. More specifically, the unique portion mark is recorded as information indicating the position of the unique portion. The unique portion mark is previously recorded at the time of manufacturing the sheet, and is not recorded by the printing apparatus of the embodiment.

The unique portion mark may be one that can be detected by the mark sensor17, such as a simple rectangle, a bar code, a QR code, a specific pictorial figure, and a character. In addition to that, the mark is recorded in a state where it can be determined whether the unique region is located on the first surface of the sheet, or on the second surface that corresponds to the reverse side thereof. The mark is recorded at the position in the vicinity of each of the unique portions and slightly away from the downstream side of the unique portion (front end side of the roll paper).

In addition, the information indicating the position of the unique portion existing on the sheet is not limited to one that is recorded as the unique portion mark in the middle of the sheet, but may be one that is recorded collectively in the form of the bar code, for example, at the front end of the sheet. Furthermore, the information is not necessarily recorded on the sheet itself, but the structure may be employed in which the information is collectively recorded on a package for packing the sheet to be input by a user to the host device. Furthermore, the structure may be employed in which a memory media in which the information is collectively recorded is attached to the package of the sheet and a user inputs the information to the host device. The information is acquired by reading out the information input in the host device.

In the printing apparatus of the present embodiment, the mark sensor17is provided as an optical sensor on the side of the sheet feeding unit1. Furthermore, the mark for identifying the unique portion of the roll of paper is recorded only on the first surface in a state where it can be determined whether the unique portion is located on the first surface of the sheet, or on the second surface that corresponds to the reverse side thereof. More specifically, the marked portion cannot be detected when the sheet is fed from the reversing unit9when the printing is executed on the second surface, so that the position of the marked portion upon printing on the second surface is estimated from the data based on the detection of the marked portion upon printing on the first surface, and then the avoiding operation is carried out.

FIGS. 3A and 3Bare diagrams showing marks recorded on the continuous sheet. The continuous sheet may include a unique portion, such as a stain and a connecting portion between the sheets, which is a region composed of a part of the sheet whose characteristic differs from the rest of the sheet in order to reduce the manufacturing cost. When the continuous sheet is stained in the manufacturing process, regarding the entire continuous sheet as being defective due to a partial defect may result in increase in the manufacturing cost.

Furthermore, the sheets having the length less than the predetermined length which are produced in the manufacturing process are not suitable for products as they are, but there is no problem in terms of the quality. Therefore, a single sheet may be made by joining these sheets. The region on the continuous sheet including the unique portion, such as a stain and a connecting portion between the sheets, is the region that is inappropriate for printing an image as a final product. Then, a mark is previously recorded in the vicinity of the unique portion at the time of manufacturing the continuous sheet, and is detected at the time of printing. The printing is thus executed while avoiding the region including the unique portion and the mark (hereinafter referred to as a unique region).

FIG. 3Ais a diagram showing a mark in the case where the unique portion on the continuous sheet is located on the first surface. The upper side is the first surface and the lower side is the reverse side thereof (the second surface located at the same position as the first surface). A stain31athat is a unique portion is located on the first surface of the continuous sheet30a, and a single line-shaped mark32aindicating that the unique portion is located on the first surface is recorded in the vicinity thereof on the reverse side. There is no unique portion such as a stain on the reverse side thereof.

FIG. 3Bis a diagram showing a mark in the case where the unique portion on the continuous sheet is located on the second surface. The upper side is the first surface and the lower side is the reverse side thereof (the second surface located at the same obverse/reverse position as the first surface). A stain31bthat is a unique portion is located on the second surface of the continuous sheet30b, and two line-shaped mark32bindicating that the unique portion is located on the second surface is recorded in the vicinity thereof on the reverse side, i.e., on the first surface.

In theFIG. 3B, there is no unique portion such as a stain even in the vicinity of the mark32b. In addition, the mark is not limited to the line-shaped mark as illustrated in the present invention. Furthermore, in addition to the recording at the time of manufacturing, the mark can be formed by a tape, a notch, a bore and the like.

FIG. 4is a flow chart showing an operational sequence of the duplex printing. The processing in the printing operation will be described below along the flow chart. The processing is achieved by the control by the control unit13.

At step S401, a first surface print schedule is created based on the instruction of printing. The first surface print schedule is the data that defines the sequence of items such as a plurality of unit images to be sequentially printed on the first surface of the continuous sheet, cut marks formed in a margin region between the images adjacent to each other, a preliminary ejection pattern, an ejection failure monitoring pattern, a margin region. In addition, the preliminary ejection pattern is the pattern of ejection of ink that does not contribute to printing, and the preliminary ejection is executed as a part of maintenance operations of the print head. The procedure proceeds to step S402, and, at step S402, the unit images and maintenance patters are sequentially printed on the continuous sheet in the predetermined order in accordance with the first surface print schedule that is created at step S401.

Then, at step S403, it is determined whether all of the printings on the first surface defined in the first surface print schedule are completed (YES) or not (NO). If it is determined to be YES at step S403, a first surface print sequence for is terminated and the procedure proceeds to step S406. In contrast, if it is determined to be NO at step S403, the procedure proceeds to step S404.

At step S404, it is determined whether the mark sensor17detects the marked portion on the continuous sheet during the printing. IF it is determined to be YES, the procedure proceeds to step S405. If it is determined to be NO, the procedure returns to step S403to repeat the processing.

At step S405, the update processing of the first surface print schedule is executed. The update processing of the print schedule executes setting of the print unavailable region corresponding to the detected mark and insertion of the preliminary ejection region. Step S405will be described in detail usingFIG. 5. The termination of the printing on the first surface is determined at step S403. The procedure proceeds to step S406, and the latest first surface print schedule is stored in the memory (the RAM or HDD) of the control unit. If the originally generated schedule is not deleted, that can be maintained without storing a new one.

At step S407, the data in the schedule recorded in the memory is read out. Then, the second surface print schedule is created at step S408. The creating of the schedule is executed based on the first surface print schedule read out at step S407. This is because it is necessary to correctly align the unit images with the unit images printed on the first surface so as to print them on the second surface. When the print unavailable region is set in the first surface print schedule, the print unavailable region is set also in the section concerned on the second surface of the sheet.

At step S409, the unit image and maintenance patterns are sequentially printed on the second surface (the reverse surface) of the continuous sheet, which is rolled by the winding rotary body, in a predetermine order in accordance with the created second surface print schedule.

At step S410, it is determined whether all of the printing on the second surface defined in the second surface print schedule are completed (YES) or not (NO). If it is determined to be YES, it means that all the duplex printing is completed, so that the sequence is terminated. If it is determined to be NO, the procedure returns to step S410to repeat the processing.

FIG. 5is a flow chart showing an operational sequence of the update processing of the first surface print schedule at step S405inFIG. 4.

At step S501, the region of a predetermined length is created anterior and posterior to the mark, and the unique region is created in the region on the reverse surface that corresponds to the region of the predetermined length. The unique region is the region which includes the unique portion composed of a part of the sheet having the characteristic different from the rest of the sheet. The length of the region may be determined previously, or may be settable at the printing apparatus. At step S502, it is determined whether the unique region is located on the first surface or the second surface by the mark pattern.

Also in the present embodiment, a single-line mark means that the unique region is located on the first surface, whereas a double-line mark means that the unique region is located on the second surface. If it is determined that the unique region is located on the first surface, the procedure proceeds to step S503. If it is determined that the unique region is located on the second surface, the procedure proceeds to step S504.

At step S503, a preliminary ejection region of the first surface is kept from the trailing edge of the unique region created at step S501toward the trailing edge side of the sheet (in a normal region following the unique region). This is because the unique portion is located in the unique region on the first surface, and thus the unique region on the first surface cannot be used as the preliminary ejection region.

At step S504, a preliminary ejection region of the first surface (the first surface) is kept from the trailing edge of the unique region created at step S501toward the leading edge side of the sheet, i.e., inside of the unique region (in the unique region). This is because the unique portion is located on the second surface, and thus the unique region on the first surface that is located at the reverse surface corresponding thereto is merely marked. There is no problem in quality except for the marked portion, and the portion can be used as the preliminary ejection region.

Then, the procedure proceeds to step S505. At step S505, a preliminary ejection region of the second surface (the second surface) is kept on the leading edge side of the sheet of the unique region created at step S501. This is because the printing on the second surface is executed from the trailing edge side of the sheet, so that, when the printing is executed, the unique region comes first, followed by the preliminary ejection region (the preliminary ejection region of the second surface) that is on the leading edge side of the sheet. Furthermore, since the unique portion is located on the second surface, the unique region on the second surface cannot be used as the preliminary ejection region.

At step S506, the printable image is settled in the position anterior to the unique region if the unique portion is located on the first surface, while being settled in the position anterior to the region of the preliminary ejection length of the second surface that is kept anterior to the unique region. More specifically, when the image to be printed is scheduled from the leading edge side of the sheet, it is determined to the extent of which image the printing is executed anterior to the unique region and from which image the printing is started by skipping the unique region.

At step S507, the start position and the end position of the print unavailable region of the first surface is defined. The start position of the print unavailable region is set to be the trailing edge of the image to be printed anterior to the unique region, which is settled at step S506. The end position of the print unavailable region is set to be the start position of the preliminary ejection region of the first surface that is kept at step S503if it is determined at step S502that the unique region is located on the first surface, or at step S504if it is determined that the unique region is located on the second surface. Then, at step S508, the preliminary ejection region of the first surface is inserted posterior to the print unavailable region. Then, at step S509, the position for inserting a maintenance pattern, such as an ejection failure monitoring pattern, to the following image is updated.

The processing for keeping the print unavailable region and the preliminary ejection region in the vicinity of a mark in a case of detecting the mark will be described below usingFIGS. 6 to 14.

FIGS. 6 to 9are diagrams showing the unique region assigned in the vicinity of a mark indicating that the unique portion is located on the first surface when the mark is detected. In the figures, the upper side of the sheet30ais the first surface, the lower side is the second surface, the left side is the leading edge side of the sheet, and the right side is the trailing edge side of the sheet. Furthermore, the printing direction of the first surface is the direction from the leading edge side of the sheet toward the trailing edge side of the sheet, and the printing direction of the second surface is in the opposite direction thereof.FIG. 6is a diagram showing the unique region of a predetermined length including the unique portion31acreated anterior and posterior to the mark32aby detecting the mark32a.

A unique region of the first surface601is defined between a start position602and an end position603. Furthermore, a unique region of the second surface604is created on the reverse side thereof. The unique region of the second surface604is defined between a start position603and an end position602. This region is the region corresponding to the reverse side of the unique region of the first surface601where the unique portion31aexists, and does not include the unique portion.

FIG. 7is a diagram showing a preliminary ejection region of the first surface611that is kept on the trailing edge side of (posterior to) the sheet of the end position603of the unique region of the first surface after the unique regions are created on the first and second surfaces. The preliminary ejection region of the first surface611is provided between the end position603and the end position612of the unique region of the first surface.

FIG. 8is a diagram showing a print unavailable region of the first surface621. In a case of updating the first surface print schedule, the images are arranged from the leading edge side of the sheet, and it is necessary to prevent the images and the unique region of the first surface601from overlapping with each other. At that time, the start position622of the print unavailable region of the first surface621serves as the trailing edge of the image to be printed anterior to the unique region of the first surface601. Furthermore, the interval between the start position622of the print unavailable region of the first surface and the start position602of the unique region of the first surface601varies depending on the size of the image to be printed and the positional relationship with the mark.

FIG. 9is a diagram showing a print unavailable region of the second surface631and a preliminary ejection region of the second surface641which are kept at the time of creating the second surface print schedule. When the second surface print schedule is created, the locations of the print unavailable region of the first surface621and the preliminary ejection region of the first surface611on the first surface are already revealed. Therefore, when the images to be printed on the second surface are arranged from the trailing edge side of the sheet, the trailing edge of the image to be printed on the reverse surface of the image that is arranged on the trailing edge side of the sheet of the preliminary ejection region of the first surface611serves as the start position632of the print unavailable region of the second surface631.

At that time, the start position632of the print unavailable region of the second surface631corresponds with the end position612of the preliminary ejection region of the first surface611. The length of the print unavailable region of the second surface631is same as that of the print unavailable region of the first surface621, and the end position633of the print unavailable region of the second surface631serves as the start position of the preliminary ejection region of the second surface641. Since the end position642of the preliminary ejection region of the second surface corresponds with the start position622of the print unavailable region of the first surface, the alignment of the images on the first surface and the second surface is correctly executed.

As described above, when the unique portion is located on the first surface, the print unavailable region of the first surface621includes the unique region of the first surface601, and the printing on the unique region of the first surface601is completely avoided. Furthermore, the print unavailable region of the second surface631does not include the unique portion of the second surface604, and the unique region of the second surface604is utilized as the preliminary ejection region.

FIGS. 10 to 14are diagrams showing the unique region assigned in the vicinity of a mark indicating that the unique portion is located on the second surface when the mark is detected. In the figures, the upper side of the sheet30bis the first surface, the lower side is the second surface, the left side is the leading edge side of the sheet, and the right side is the trailing edge side of the sheet. Furthermore, the printing direction of the first surface is the direction from the leading edge side of the sheet toward the trailing edge side of the sheet, and the printing direction of the second surface is in the opposite direction thereof.FIG. 10is a diagram showing the unique region of a predetermined length including the unique portion31bcreated anterior and posterior to the mark32bby detecting the mark32a. The start position of the unique region of the first surface701is denoted by702, and the end position thereof is denoted by703. Furthermore, a unique region of the second surface704is created on the reverse side thereof. The unique region of the second surface704is defined between the start position703and the end position702.

FIG. 11is a diagram showing a preliminary ejection region of the first surface711that is kept on the leading edge side of the sheet of the end position703of the unique region of the first surface after the unique regions are created on the first and second surfaces. The preliminary ejection region of the first surface711is defined between the start position712and the end position703. Here, the unique region of the first surface701overlaps the preliminary ejection region of the first surface711, but does not include the unique part. Therefore, the region can be used as a preliminary ejection region.

FIG. 12is a diagram showing a region of the preliminary ejection length of the second surface721that is kept on the leading edge side of the sheet of the start position702in the unique region of the first surface701. When the mark indicating that the unique portion is located on the second surface is detected, it is necessary to keep the preliminary ejection region of the second surface on the leading edge side of the sheet that is nearer than the end position702of the unique region of the second surface, in a case of creating the second surface print schedule. Therefore, the region having the length required for the preliminary ejection of the second surface is previously kept as the region721of the preliminary ejection length of second surface at the time of updating the first surface print schedule. In this way, the region721of the preliminary ejection length for the second surface is defined between the start position722and the start position702of the unique region of the first surface701.

FIG. 13is a diagram showing a print unavailable region of the first surface731. In a case of updating the first surface print schedule, the images are arranged from the leading edge side of the sheet, and it is necessary to prevent the images and the region721of the preliminary ejection length of the second surface from overlapping with each other. At that time, the start position732of the print unavailable region of the first surface731serves as the trailing edge of the image to be printed anterior to the region721of the preliminary ejection length for the second surface. Furthermore, the interval between the start position732of the print unavailable region of the first surface and the start position722of the region721of the preliminary ejection length for the second surface varies depending on the size of the image to be printed and the positional relationship with the mark. The end position of the print unavailable region of the first surface731is the start position712of the preliminary ejection region of the first surface711.

FIG. 14is a diagram showing a print unavailable region of the second surface741and a preliminary ejection region of the second surface751which are kept at the time of creating the second surface print schedule. When the second surface print schedule is created, the locations of the print unavailable region of the first surface731and the preliminary ejection region of the first surface711on the first surface are already revealed. Therefore, when the images to be printed on the second surface are arranged from the trailing edge side of the sheet, the trailing edge of the image to be printed on the reverse surface of the image that is arranged on the trailing edge side of the sheet of the preliminary ejection region of the first surface711serves as the start position742of the print unavailable region of the second surface741.

At that time, the start position742of the print unavailable region of the second surface corresponds with the end position703of the unique region of the first surface701and the preliminary ejection region of the first surface711. The length of the print unavailable region of the second surface741is same as that of the print unavailable region of the first surface731, and the end position743of the print unavailable region of the second surface741serves as the start position of the preliminary ejection region of the second surface751. In addition, the preliminary ejection region of the second surface751also can be arranged immediately anterior to the end position702of the unique region of the second surface704, i.e., on the exact reverse side of the region721of the preliminary ejection length for the second surface.

In such a case, however, producing a gap between the preliminary ejection region of the second surface751and the following image may cause deterioration in the image quality. It is thus desirable to minimize the interval between the preliminary ejection region of the second surface751and the following image. Therefore, the start position742of the print unavailable region of the second surface741corresponds with the end position703of the preliminary ejection region of the first surface711, and the end position752of the preliminary ejection region of the second surface751corresponds with the start position732of the print unavailable region of the first surface731. The positions are brought into correspondence with each other in this way, so that the alignment of the images on the first surface and the second surface is correctly executed.

As described above, when the unique portion is located on the second surface, the print unavailable region of the second surface741includes the unique region of the second surface704, and the printing on the unique region of the second surface704is completely avoided. Furthermore, the print unavailable region of the first surface731does not include the unique region of the first surface701, and the unique region of the first surface701is effectively utilized as the preliminary ejection region.

Then, an example of update processing of the first surface print schedule, and an example of creating processing of the second surface print schedule will be described usingFIGS. 15A to 16C. In each ofFIGS. 15A to 15CandFIGS. 16A to 16C, the upper side of the figure is the leading edge side of the continuous sheet, and the lower side is the trailing side of the continuous sheet. More specifically, the printing proceeds from the upper side to the lower side at the time of printing on the first surface (FIGS. 15A and 15B, andFIGS. 16A and 16B), whereas the printing proceeds from the lower side to the upper side at the time of printing on the second surface (FIG. 15CandFIG. 16C).

FIG. 15Ais a diagram showing an initial first surface print schedule created at step S401(refer toFIG. 4). In this case, the schedule is created so that the preliminary ejection is inserted at the top of the printing, and the ejection failure monitoring patterns are inserted at predetermined intervals and at the end of the image.FIG. 15Bis an example of the updated first surface print schedule in a case where a marked portion detection processing at step S404detects that the unique portion is located on the first surface side during the printing.

The unique region of a predetermined length is created anterior and posterior to the mark32a, and it is determined to the extent of which image the printing can be executed anterior to the unique region. If the determination result is obtained in which the printing can be done to a cut mark81posterior to an image F, the start position of a print unavailable region82is defined at the trailing edge of the cut mark81posterior to the image F. The end position of the print unavailable region82is still at the end position of the unique region. The print unavailable region82is defined, and then a preliminary ejection region of the first surface83and a cut mark84are inserted posterior thereto. With regard to a following image G and the images subsequent thereto, the insertion position is updated so that the maintenance patterns are inserted at predetermined intervals.

FIG. 15Cis an example of the second surface print schedule created at step S408based on the updated first surface print schedule inFIG. 15B. The schedule is created so that each of the images is arranged at the position on the second surface which is opposite to each of the images on the first surface, such as an image D to an image V. On the second surface, since the printing is executed from the trailing edge side of the continuous sheet, the trailing edge of the cut mark85posterior to an image S opposite to an image G serves as the start position of a print unavailable region of the second surface86. The length of the print unavailable region of the second surface86is equal to that of the print unavailable region of the first surface82, and a preliminary ejection region of the second surface87and a cut mark88are inserted posterior to the print unavailable region of the second surface86.

As described above, the print unavailable region is arranged so that the image is not arranged in the unique region of the first surface, and the preliminary ejection region of the first surface83is arranged posterior thereto. Furthermore, the preliminary ejection region of the second surface87is arranged at the position overlapped with the print unavailable region of the first surface82. This is because the marked portion detection processing at step S404(refer toFIG. 4) detects that the unique portion is located on the first surface side, so that the second surface does not include any unique portions and can be utilized for the maintenance processing of the print head.

FIG. 16Ais a diagram showing an initial first surface print schedule created at step S401(refer toFIG. 4). Similar toFIG. 15A, the schedule is created so that the preliminary ejection is inserted at the top of the printing, and the ejection failure monitoring patterns are inserted at predetermined intervals and at the end of the image.FIG. 16Bis an example of the updated first surface print schedule in a case where a marked portion detection processing at step S404detects that the unique portion is located on the second surface side opposite to the first surface during the printing.

First, a unique region of a predetermined length is created anterior and posterior to the mark32b. The actual unique portion such as a stain is located on the reverse side of the unique region created here, i.e., in the unique region of the second surface, so that the first surface can be utilized for the head maintenance except for the marked portion. Therefore, the preliminary ejection region of the first surface93is kept from the trailing edge of the unique region to the inside of the unique region, i.e., toward the leading edge side of the sheet, and further the region of the preliminary ejection length of the second surface is kept from the leading edge of the unique region toward the leading edge side of the sheet.

In this state, it is determined to the extent of which image the printing can be executed anterior to the kept region of the preliminary ejection length of the second surface. If it is resultingly determined that the printing can be executed to an image E, the trailing edge of a cut mark91posterior to the image E serves as the start position of the print unavailable region92, and the end position of the print unavailable region92is positioned on the side of the leading edge of the sheet for the length from the trailing edge of the unique region to the preliminary ejection region of the first surface93. The print unavailable region92is defined, and then the preliminary ejection region of the first surface94is inserted posterior thereto. The preliminary ejection region of the first surface93is inserted, followed by a cur mark94. Then, a following image F and the images subsequent thereto are arranged. Furthermore, the insertion position is updated so that the maintenance patterns are inserted at predetermined intervals.

FIG. 16Cis an example of the second surface print schedule created at step S408based on the updated first surface print schedule inFIG. 16B. The schedule is created so that each of the images is arranged at the position on the first surface which is opposite to each of the images on the second surface, such as an image D to an image V. On the second surface, since the printing is executed from the trailing edge side of the continuous sheet, the trailing edge of the cut mark95posterior to an image T opposite to an image F serves as the start position of a print unavailable region of the second surface96.

The length of the print unavailable region of the second surface96is equal to that of the print unavailable region of the first surface92, and a preliminary ejection region of the second surface97and a cut mark98are inserted posterior to the print unavailable region of the second surface96.

As described above, the print unavailable region96is arranged so that the image is not arranged in the unique region of the second surface, and the preliminary ejection region97is inserted posterior thereto. Furthermore, the preliminary ejection region of the first surface93is arranged inside of the unique region of the first surface. This is because the marked portion detection processing at step S404detects that the unique portion is located on the second surface side, so that the first surface does not include any unique portions and can be utilized for the maintenance processing of the print head.

In the present embodiment, it is confirmed which of the surfaces out of the first and second surfaces include a unique portion by means of a mark applied on the sheet, and the unique region is created at the predetermined length anterior and posterior to the mark. Then, when the first surface includes the unique portion, the preliminary ejection region is provided posterior to the unique region on the first surface and, on the second surface, the preliminary ejection region is provided posterior to the print unavailable region including the unique region on the second surface. In contrast, when the second surface includes the unique portion, the preliminary ejection region including the trailing edge portion of the unique region of the first surface is provided in the unique region on the first surface and, on the second surface, the print unavailable region is provided, followed by the preliminary ejection region.

If a more general, a print unavailable region including a unique portion and a maintenance region following thereto are set on a specific sheet surface on which a unique portion exists, and also, on a sheet surface which is a reverse side of the specific sheet surface, a print unavailable region is set so as to include a region corresponding to the maintenance region, and also a maintenance region following thereto is set. The regions (a total of the print unavailable regions and the maintenance regions), which are set on each of the specific sheet surface and the sheet surface on the reverse side thereof so that an image cannot be printed due to the unique portion, correspond with each other on the observe and reverse sides of the sheet in terms of locations and lengths.

Furthermore, in the continuous sheet for use in the printing method based on such a technical idea, information indicating the location of the unique portion is previously recorded on the continuous sheet itself. Alternatively, the information is collectively recorded on a package of the continuous sheet, or is collectively recorded in a memory media attached to the package. The unique portion thus can be detected by acquiring the information. Namely, the continuous sheet itself is characteristic.

According to the embodiments described above, even If a unique portion exists on a sheet when a plurality of images is sequentially printed on both the surfaces of the continuous sheet, the optimum scheduling including maintenance of the print head enables the amount of consumption of the sheet to be suppressed as a whole.

This application claims the benefit of Japanese Patent Application No. 2012-169937, filed Jul. 31, 2012, which is hereby incorporated by reference herein in its entirety.