JP2016182759A - Method for adjusting printing position and printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing position adjustment method capable of suitably adjusting a conveyance speed and a printing positional deviation during both surface printing and back printing in a printing device which can perform double-side printing.SOLUTION: A back adjustment pattern corresponding to a real image is printed together with a normal test pattern in surface printing. After that, in back adjustment, a test pattern is printed and read in a state where a sheet is conveyed while bringing a conveyance roller into contact with an area where an adjustment pattern is printed.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a printing apparatus capable of double-sided printing on a sheet and a printing position adjusting method.

  In an apparatus that prints an image on a sheet that is conveyed at a predetermined speed using a print head that is fixed in the apparatus, if the sheet conveyance speed varies or the print head includes an installation error, the output image has a density. Unevenness or color shift may be confirmed. For this reason, it is preferable to appropriately detect the sheet conveyance speed and the print position of each print head, and adjust the conveyance speed and the drive timing of the print head based on the detection result.

  In Patent Document 1, in a configuration in which a predetermined number of timing signals are generated while a conveyance roller that conveys a sheet rotates once, the drive timing of the print head is controlled based on the sheet conveyance amount per unit rotation amount of the conveyance roller. A method is disclosed. Further, in Patent Document 2, a predetermined test pattern is printed on a print head, the test pattern is read by a reading unit disposed downstream of the print head in the transport direction, and the print pattern is printed based on the read result. A method for correcting misregistration is disclosed. If the methods of Patent Literature 1 and Patent Literature 2 are employed, the conveyance speed and the print position deviation can be appropriately adjusted at a timing such as when the sheet type is exchanged.

JP 2012-179903 A JP 2012-35477 A

  However, in the case of a printing apparatus capable of printing on both sides of a sheet, the conveyance speed and the degree of variation thereof vary between the front surface and the back surface of the sheet. More specifically, the sheet and the sheet are conveyed in the state in which the blank area of the sheet is in contact with the surface of the conveyance roller and in the state in which the sheet surface on which the image has already been printed is in contact with the surface of the conveyance roller. The friction with the roller is different, and the conveyance speed and its variation also change.

  FIGS. 1A and 1B are diagrams for explaining the conveyance speed and the degree of variation in each of the front surface print and the back surface print. FIG. 1A shows a case where a predetermined image including a high density region and a low density region is printed at random. At the time of front side printing, the sheet is conveyed in a state where the blank paper region (back surface) is in contact with the surface of the conveyance roller, so that the friction between the surface of the conveyance roller and the back surface of the sheet is stable and the conveyance speed is also stable. On the other hand, at the time of printing on the back surface, the sheet is transported in a state where the image surface that has absorbed the ink is in contact with the surface of the transport roller, so the friction between the surface of the transport roller and the back surface of the sheet is greater than at the time of front surface printing, The conveyance speed is also relatively increased. Since the amount of ink absorbed by the sheet is different depending on whether it is a high density region or a low density region, the friction coefficient and thus the transport speed also change. As a result, the variation in the conveyance speed during backside printing is greater than during frontside printing.

  On the other hand, FIG. 1B shows a case where the predetermined image described in FIG. 1A is printed using different temperature / humidity environments or different types of sheets. Although the state in which the conveyance speed on the back surface is larger than the conveyance speed on the front surface does not change, each conveyance speed and the degree of variation are different from those in FIG.

  In such a state, even if the method of Patent Document 1 or Patent Document 2 is employed during printing on the front surface to acquire the conveyance speed or the print position deviation, the correction amount obtained therefrom is effective at the time of printing on the back surface. I can not say. Even if correction of the conveyance speed and drive timing is performed based on the results obtained at the time of front side printing, the sheet is conveyed at a different conveyance speed and variation at the time of reverse side printing, so appropriate correction is made. It is because it becomes impossible to do.

  The present invention has been made to solve the above problems. Therefore, an object of the present invention is to provide a printing apparatus and a printing method capable of suitably adjusting the conveyance speed and the print position deviation in both the front surface printing and the back surface printing in the printing apparatus capable of performing double-sided printing. That is.

  To this end, the present invention is a method for adjusting a print position for printing an image on both sides of a sheet, and using a print head on the first surface of the sheet in a state where a conveyance roller is conveying the sheet. A uniform adjustment pattern is printed, the front and back surfaces of the sheet are reversed so that the second surface of the sheet faces the print head, and the conveyance roller contacts the area where the adjustment pattern is printed. While the sheet is being conveyed, a test pattern is printed on the second surface of the sheet using the print head, and the test pattern is read to adjust the print position of the print head on the second surface. When the correction data is generated and the image is printed on the second surface, the print data is printed using the correction data. And adjusting the.

  According to the present invention, in a printing apparatus capable of double-sided printing, it is possible to suitably adjust the print position deviation during front-side printing and back-side printing.

Diagram showing front-and-back printing speed and variation Schematic of the cross section showing the internal configuration of the printing device The block diagram which shows the concept of the control part 13 Diagram for explaining operations in duplex printing mode and simplex printing mode The figure for demonstrating the detailed structure of a printing part. Flowchart for explaining the print position adjustment mode of the first embodiment The figure explaining the layout of the image printed on the front and back of the sheet | seat of 1st Embodiment Flowchart for explaining a print position adjustment mode of the second embodiment The figure explaining the layout of the image printed on the front and back of the sheet | seat of 2nd Embodiment The figure which shows the relationship between the duty of a back surface adjustment pattern, and a correction value

(First embodiment)
Hereinafter, an embodiment of a printing apparatus using an ink jet system will be described as an example of a sheet conveying apparatus that can be employed in the present invention. The printing apparatus of the present embodiment is a high-speed line printer capable of performing single-sided printing and double-sided printing on a long continuous sheet. For example, it is suitable for the field of printing a large number of sheets in a print laboratory or the like.

  FIG. 2 is a schematic cross-sectional view showing the internal configuration of the printing apparatus 100. The printing apparatus 100 according to the present embodiment can perform double-sided printing on a first surface (front surface) and a second surface (back surface) of a sheet using a sheet wound in a roll shape. Inside the printing apparatus 100, there are a sheet supply unit 1, a decurling unit 2, a skew correction unit 3, a printing unit 4, an inspection unit 5, a cutter unit 6, an information printing unit 7, a drying unit 8, a reversing unit 9, and a discharge conveyance. Unit 10, sorter unit 11, discharge unit 12, and control unit 13 are provided. The sheet is conveyed by a conveyance mechanism including a roller pair and a belt along a sheet conveyance path indicated by a solid line and a broken line in the drawing, and is processed in each unit.

  The sheet supply unit 1 is a unit for holding and supplying a continuous sheet wound in a roll shape. The sheet supply unit 1 can store two rolls R <b> 1 and R <b> 2, and is configured to selectively pull out and supply a sheet. The number of rolls that can be stored is not limited to two, and one or three or more rolls may be stored.

  The decurling unit 2 is a unit that reduces curl of sheets supplied from the sheet supply unit 1 or the reversing unit 9. In the decurling unit 2, two pinch rollers are nipped with respect to one driving roller, and the sheet is curved and conveyed so as to give a warp in a direction opposite to the curl. By passing the decurling unit 2, curling due to being wound in a roll shape is reduced, and the sheet surface becomes smooth.

  The skew correction unit 3 is a unit that corrects skew (inclination with respect to the original traveling direction) of the sheet that has passed through the decurling unit 2. By pressing the sheet end on the reference side against the guide member, the skew in the traveling direction of the sheet is corrected.

  The printing unit 4 is a processing unit that forms an image by performing a printing process on the conveyed sheet from above with the print head 14. The printing unit 4 includes a plurality of rollers that convey the sheet and various sensors. The print head 14 is a line-type print head formed by arranging a plurality of inkjet-type nozzles within a range that covers the maximum width of a sheet that is assumed to be used. In the print head 14, a plurality of nozzle rows corresponding to the ink colors are arranged in parallel along the transport direction. In this example, there are seven nozzle rows corresponding to seven colors of C (cyan), M (magenta), Y (yellow), LC (light cyan), LM (light magenta), G (gray), and K (black). . Note that the number of colors and the number of nozzle rows are not limited to seven. As the inkjet method, a method using a heating element, a method using a piezo element, a method using an electrostatic element, a method using a MEMS element, or the like can be adopted. Each color ink is supplied from the ink tank to the print head 14 via an ink tube. The print unit 4 will be described in detail later.

  A mark reader 18 is provided between the skew correction unit 3 and the printing unit 4. The mark reader 18 is a reflective optical sensor for timing in order to match the print position on the back surface (second surface) with the print position on the front surface (first surface) during double-sided printing. When printing the front surface (first surface), the print head 14 prints a mark for indicating the position of the image on the surface of the sheet, but when printing the back surface (second surface), the mark is positioned on the back surface. Yes. Therefore, the mark reader 18 receives a light source (for example, a white LED) that irradiates the back surface of the sheet and a photodiode or an image sensor that detects reflected light of the back surface for each RGB component so that the back surface of the sheet can be inspected. It is composed of a vessel.

  The inspection unit 5 optically reads the test pattern or image printed on the sheet by the printing unit 4 using a scanner, and inspects the nozzle state of the print head, the sheet conveyance state, the image position, etc., and the image is printed correctly. This is a unit for determining whether or not. The scanner has a CCD image sensor and a CMOS image sensor. A test pattern for detecting a print position shift described later is also inspected by the inspection unit 5.

  The cutter unit 6 is a unit including a mechanical cutter that cuts a printed sheet into a predetermined length. The cutter unit 6 also includes a plurality of conveyance rollers for sending out the sheet to the next process. When performing double-sided printing, the cutter unit 6 does not perform cutting processing on the sheet at the stage where printing on the front surface (first surface) has been completed. Only the single-sided printed sheet and the sheet that has been printed on the back surface (second surface) in double-sided printing are cut in units of pages. A trash can 17 is provided in the vicinity of the cutter unit 6 and accommodates a blank area cut off by the cutters 20a and 20b.

  The information print unit 7 is a unit that prints print information (unique information) such as a serial number and date in a non-print area of the cut sheet. Characters and codes are printed by an inkjet method, a thermal transfer method, or the like. A sensor 21 for detecting the leading edge of the cut sheet is provided on the upstream side of the information printing unit 7 and the downstream side of the cutter unit 6, and the timing at which information is printed by the information printing unit 7 is determined by the sensor 21. Is controlled based on the timing at which the tip is detected.

  The drying unit 8 is a unit for heating the sheet printed by the printing unit 4 to promote drying of the applied ink. Inside the drying unit 8, hot air is applied at least from the lower surface side to the passing sheet to dry the ink application surface. The drying method is not limited to the method of applying hot air, and may be a method of irradiating the sheet surface with electromagnetic waves (such as ultraviolet rays and infrared rays).

The sheet conveyance path from the sheet supply unit 1 to the drying unit 8 is referred to as a first path. The first path has a U-turn shape between the printing unit 4 and the drying unit 8.
The reversing unit 9 is a unit for temporarily winding a continuous sheet on which front surface printing has been completed when performing double-sided printing, and reversing the front and back. The reversing unit 9 is provided in the middle of a route (referred to as a second route) from the drying unit 8 through the decurling unit 2 to the printing unit 4 for supplying the sheet that has passed through the drying unit 8 to the printing unit 4 again. It has been. The reversing unit 9 includes a winding rotary body (drum) for winding the sheet. The continuous sheet that has been printed on the front surface and has not been cut in units of pages is temporarily wound around the winding rotary member. When the winding is finished, the winding rotary body rotates in the reverse direction, and the winding sheet is sent to the printing unit 4 through the decurling unit 2 and the skew correction unit 3. This sheet is fed into the printing section with the back surface (second surface) located on the back surface facing the print head 14 at the time of front surface printing, and the end portion which is the rear edge at the time of front surface printing as the leading edge. . The specific operation of duplex printing will be described later.

  The discharge conveyance unit 10 is a unit for conveying the sheet cut by the cutter unit 6 and dried by the drying unit 8 and delivering the sheet to the sorter unit 11. The discharge conveyance unit 10 is provided in a route (referred to as a third route) different from the second route in which the reversing unit 9 is provided. In order to selectively guide the sheet conveyed on the first path to one of the second path and the third path, a path switching mechanism having a movable flapper is provided at a branch position of the path.

The sorter unit 11 and the discharge unit 12 are provided on the side of the sheet supply unit 1 and at the end of the third path. The sorter unit 11 is a unit for sorting printed sheets for each group as necessary. The sorted sheets are discharged to the discharge unit 12 including a plurality of trays. In this way, the third path has a layout that passes below the sheet supply unit 1 and discharges the sheet to the opposite side of the printing unit 4 and the drying unit 8 across the sheet supply unit 1.
The control unit 13 is a unit that controls each unit of the entire printing apparatus 100. The control unit 13 includes a controller 15 having a CPU, a storage device, and the like, an external interface, and an operation unit on which a user inputs and outputs. The operation of the printing apparatus 100 is controlled based on a command from a host device 16 such as a controller or a host computer connected to the controller via an external interface.

  FIG. 3 is a block diagram illustrating the concept of the control unit 13. A controller 15 (range enclosed by a broken line) included in the control unit 13 includes a CPU 201, a ROM 202, a RAM 203, an HDD 204, an image processing unit 207, an engine control unit 208, and an individual unit control unit 209. A CPU 201 (central processing unit) controls the operation of each unit of the printing apparatus 100 in an integrated manner. The ROM 202 stores programs to be executed by the CPU 201 and fixed data necessary for various operations of the printing apparatus 100. The RAM 203 is used as a work area for the CPU 201, used as a temporary storage area for various received data, and stores various setting data. The HDD 204 (hard disk) can store and read programs executed by the CPU 201, print data, and setting information necessary for various operations of the printing apparatus 100. The operation unit 206 is an input / output interface with the user, and includes an input unit such as a hard key and a touch panel, and an output unit such as a display for presenting information and a sound generator.

  A dedicated processing unit is provided for units that require high-speed data processing. An image processing unit 207 performs image processing of print data handled by the printing apparatus 100. The color space (for example, YCbCr) of the input image data is converted into a standard RGB color space (for example, sRGB). Various image processing such as resolution conversion, color conversion corresponding to the ink color to be used, image analysis, image correction, and the like is performed on the image data as necessary. Print data obtained by these image processes is stored in the RAM 203 or the HDD 204. The engine control unit 208 performs drive control of the print head 14 of the print unit 4 according to print data based on a control command received from the CPU 201 or the like. The engine control unit 208 further controls the transport mechanism of each unit in the printing apparatus 100. The individual unit control unit 209 includes a sheet supply unit 1, a decurling unit 2, a skew correction unit 3, an inspection unit 5, a cutter unit 6, an information printing unit 7, a drying unit 8, a reversing unit 9, a discharge conveyance unit 10, and a sorter unit. 11 and a sub-controller for individually controlling each unit of the discharge unit 12. The individual unit control unit 209 controls the operation of each unit based on a command from the CPU 201. The external interface 205 is an interface (I / F) for connecting the controller 15 to the host device 16 and is a local I / F or a network I / F. The above components are connected by the system bus 210.

  The host device 16 is a device serving as a supply source of image data for causing the printing apparatus 100 to perform printing. The host device 16 may be a general-purpose or dedicated computer, or a dedicated image device such as an image capture having an image reader unit, a digital camera, or a photo storage. When the host device 16 is a computer, an OS, application software for generating image data, and a printer driver for the printing device 100 are installed in a storage device included in the computer. Note that it is not essential to implement all of the above processing by software, and a part or all of the processing may be realized by hardware.

  Next, the basic operation during printing will be described. Since the printing operation differs between the single-sided printing mode and the double-sided printing mode, each will be described. FIG. 4A is a diagram for explaining the operation in the single-sided printing mode. The sheet supplied from the sheet supply unit 1 and processed by the decurling unit 2 and the skew feeding correction unit 3 is printed on the front surface (first surface) by the printing unit 4. An image (unit image) having a predetermined unit length in the conveyance direction is sequentially printed on a long continuous sheet to form a plurality of images side by side. The printed sheet passes through the inspection unit 5 and is cut for each unit image in the cutter unit 6. The cut cut sheet is printed with print information on the back side of the sheet by the information printing unit 7 as necessary. Then, the cut sheets are conveyed one by one to the drying unit 8 and dried. Thereafter, the sheet is sequentially discharged and stacked on the discharge unit 12 of the sorter unit 11 via the discharge conveyance unit 10. On the other hand, the sheet left on the side of the printing unit 4 by cutting the last unit image is sent back to the sheet supply unit 1 and taken up by the roll R1 or R2. Thus, in single-sided printing, the sheet passes through the first path and the third path and is processed, and does not pass through the second path.

  FIG. 4B is a diagram for explaining the operation in the duplex printing mode. In duplex printing, a back surface (second surface) print sequence is executed after a front surface (first surface) print sequence. In the front surface print sequence, the operation in each unit from the sheet supply unit 1 to the inspection unit 5 is the same as the single-sided printing operation described above. However, the printing unit 4 prints a mark for use as a reference for the print position when printing the back surface (second surface) together with the input image data. Further, the cutter unit 6 does not perform the cutting operation for each page, and only the position of the rear end portion of the last page is cut. After passing through the drying unit 8, the sheet whose rear end is cut is guided not to the path (third path) on the discharge conveyance unit 10 side but to the path (second path) on the reversing unit 9 side. Then, it is wound around the winding rotary body of the reversing unit 9 that rotates in the forward direction (counterclockwise direction in the drawing).

  On the other hand, at the same time as the winding, the continuous sheet remaining on the upstream side in the conveying direction (on the printing unit 4 side) with respect to the cutting position is not supplied to the decurling unit 2 at the sheet leading end (cutting position). It is rewound onto one roll R1 or R2. By this rewinding, collision with the sheet supplied again in the following back surface printing sequence is avoided.

  After the above-described front surface printing sequence, the back surface printing sequence is executed. First, the winding rotary body of the reversing unit 9 rotates in the direction opposite to that during winding (clockwise direction in the drawing). As a result, the trailing edge of the wound sheet becomes the leading edge, and is sent to the printing unit 4 via the decurling unit 2, the skew correction unit 3, and the mark reader 18. The printing unit 4 performs a printing operation on the back surface (second surface) of the sheet using the mark read by the mark reader 18 as a reference. The sheet on which the second surface is printed passes through the inspection unit 5 and is cut into predetermined unit lengths set in advance in the cutter unit 6. Since the cut sheet is printed on both sides, the information print unit 7 does not print. Thereafter, the cut sheets are conveyed one by one to the drying unit 8, and sequentially discharged and stacked on the discharge unit 12 of the sorter unit 11 via the discharge conveyance unit 10. In this way, in duplex printing, the sheet is processed in the order of the first path → second path → first path → third path.

  FIG. 5 is a diagram for explaining a detailed configuration of the print unit 4. In the printing unit 4, the sheet S is sandwiched between three pairs of rollers and conveyed in the direction of the arrow. A pair of a pre-conveying roller 34 and a pre-pinch roller 35 that is driven by the pair, a pair of a main conveying roller 30 and a main pinch roller 31 that judos to this, a pair of a sub-conveying roller 32 and a sub-pinch roller 33 that judos to this pair. In this order, they are arranged from the upstream. The print head 14 is located between the conveyance roller 30 and the sub-conveyance roller 32 and ejects ink toward a sheet that is kept smooth by sandwiching these roller pairs. At this time, the timing at which the print head 14 starts ejecting ink is adjusted based on the timing at which the leading edge detection sensor 41 disposed immediately upstream detects the leading edge of the sheet.

  A rotary encoder 36 that rotates coaxially is attached to the transport roller 30 so that the amount of rotation of the transport roller 30 is detected. On the other hand, a laser Doppler velocimeter 40 is installed between the conveying roller 30 and the pre-conveying roller 34 to detect the moving distance of the sheet S moving below. Under such a configuration, the control unit 13 detects the actual conveyance amount of the sheet S with respect to the unit rotation amount of the conveyance roller 30, and based on the detected result, the main conveyance roller 30 via the engine control unit 208. The conveyance speed can be controlled. Specifically, a table based on the detected transport speed is selected from drive tables stored in advance in the ROM 202 or the like, and a stepping motor that is a drive source of the transport roller 30 is driven according to the table. In the drive table, a drive pulse table to be applied to the stepping motor in order to realize an ideal transport speed is stored in association with the actually measured transport speed.

  The control unit 13 controls the sheet conveyance so that the sheet forms a loop on the upstream side of the conveyance roller 30 and the downstream side of the sub-conveyance roller 32. In this way, by relaxing the sheet outside the pair of conveying rollers located on both sides of the print head 14, it is possible to prevent other rollers from affecting the area during printing by the print head 14. . Further, the pressing force of the main pinch roller 31 applied to the conveying roller 30 is sufficiently larger than the pressing force of the sub-pinch roller 33 applied to the sub-conveying roller 32 and the pressing force of the pre-main conveying pin 34 applied to the pre-main conveying roller 34. doing. Thereby, it is possible to maintain a state in which the sheet S is conveyed mainly as the main conveying roller 30 rotates. Although not shown in the figure, a temperature sensor and a humidity sensor are also provided around the print unit 4 so that the ambient temperature and humidity can be detected from time to time.

  The characteristic print position adjustment mode of the present invention will be described below. The print position adjustment mode is used to detect the conveyance speed of the sheet and the amount of print position deviation between the print heads so that the actual image formed on the sheet does not cause any adverse effects due to these factors. This is a mode for obtaining the correction amount of the drive timing. As described above, when performing double-sided printing, the sheet transport speed differs between front side printing and back side printing, so the print position deviation between print heads also differs between front side printing and back side printing. Of course, the appropriate correction amount is also expected to be different. For this reason, in the print position adjustment mode of this embodiment, an adjustment mode for front side printing and an adjustment mode for back side printing are prepared, and the correction amount for front side printing and the correction amount for back side printing are separately provided. To manage.

  FIG. 6 is a flowchart for explaining the steps executed by the CPU 201 of the control unit 13 when executing the print position adjustment mode. When this process is started, first, in step S11, the CPU 201 executes a preparation operation for front side printing. Specifically, after executing a predetermined pre-printing sequence such as a print head maintenance process, the sheet S is pulled out from the sheet supply unit 1 and the conveying operation is continued for a predetermined time.

  In step S <b> 12, the CPU 201 acquires the rotation amount of the main conveyance roller 30 and the movement amount of the sheet S per unit time using the rotary encoder 36 and the laser Doppler velocimeter 40. Further, the process proceeds to step S13, and the correction amount for the transport operation is set based on the result obtained in step S12. Specifically, a drive table for realizing an ideal transport speed is selected from a plurality of drive tables stored in advance in the ROM 202 or the like based on the result obtained in step S12, and the transport motor is selected according to the drive table. Drive. Thereafter, the corrected sheet conveying speed in the front surface printing is maintained.

  In step S <b> 14, the CPU 201 uses the print head 14 to print a test pattern for print position adjustment on the sheet S being conveyed. In step S15, the test pattern printed in step S14 is read using the scanner of the inspection unit 5. Further, in step S16, correction data for each of the nozzle arrays arranged in the print head is generated based on the reading result in step S15, and is stored as the first surface correction data for the surface. The first surface correction data includes correction data for correcting a print position shift between individual nozzle rows, correction data for correcting a print position shift in one nozzle row, and the like.

  Thereafter, the CPU 201 proceeds to step S17 and prints a back surface adjustment pattern in which ink droplets are uniformly applied at a predetermined duty. The back surface adjustment pattern is a state in which the area is in contact with the conveyance roller 30 at the timing when the conveyance amount is obtained, the test pattern is printed, or the test pattern is read in the adjustment mode for the front surface to be performed later. It is a pattern to produce. The back surface adjustment pattern only needs to have a duty comparable to that of a general actual image. Here, a pattern having a duty of about 50% is printed. By setting such an intermediate duty value, even if the duty of the image actually printed on the front surface is reduced or increased, the fluctuation range of the conveyance speed can be suppressed as much as possible. As described above, steps S12 to S17 are the adjustment mode for the surface.

  In the subsequent step S18, a sheet reversal process is performed. That is, the CPU 201 cuts the continuous sheet at the position where the rear end of the back surface adjustment pattern printed in step S17 has passed in the cutter unit 6, conveys the sheet S to the reversing unit 9, and reverses the front and back and the front and rear ends. In the state, it is carried into the printing unit 4 again. Thereafter, in step S21, a preparation operation for back side printing is executed, and then an adjustment mode for the back side is entered.

  Steps S22 to S26 in the back surface adjustment mode are the same as steps S12 to S16 in the front surface adjustment mode. That is, in steps S22 and S23, a correction amount at the time of back surface conveyance is obtained and set. At this timing, the roller pair of the conveyance roller 30 and the main pinch roller 31 sandwiches the region where the back surface adjustment pattern is printed in the front surface adjustment mode. Therefore, the actual transport speed is relatively higher than that at the time of front surface printing, and in step S23, a correction amount for setting a transport speed different from the front surface to the target transport speed is set.

  In step S24, a test pattern is printed while driving the carry motor with the back surface drive table set in step S23. The test pattern printed here may be the same as or different from the test pattern printed on the surface. The area where the print head 14 prints the test pattern is the back side of the area where the back surface adjustment pattern is printed in the front surface adjustment mode. Therefore, during printing, the roller pair of the conveyance roller 30 and the main pinch roller 31 sandwiches the area where the back surface adjustment pattern is printed, and using the correction amount set in step S23 in such a state, The sheet is being conveyed.

  Thereafter, in step S25, the sheet S being conveyed is inspected using the scanner of the inspection unit 5, and the test pattern printed on the back surface is read in step S24. Further, in step S26, based on the reading result in step S25, the correction amount for each of the plurality of nozzle rows in the print head 14 is obtained, and this is stored as the second surface correction data for the back surface. This is the end of the back surface adjustment mode. Further, the CPU 201 proceeds to step S27 and performs a sheet discharging operation. This completes the print position adjustment mode.

  Thereafter, when performing an actual printing operation, the CPU 201 executes the printing operation using the first surface correction data at the time of single-sided printing or double-sided printing. On the other hand, at the time of reverse side printing of double-sided printing, the printing operation is executed using the second side correction data.

  FIGS. 7A and 7B are diagrams for explaining the layout of images printed on the front and back surfaces of the sheet in the print position adjustment mode of the present embodiment. FIG. 7A shows a printed image for the front surface, and FIG. 7B shows a printed image for the back surface. As already described, the transport direction is reversed between the front surface print and the back surface print.

  In the front-side print image shown in FIG. 7A, there are a non-print area for adjusting the conveyance speed in step S12, an area for printing a test pattern in step S14, and an area for printing a back surface adjustment pattern in step S17. In this order in the transport direction. On the other hand, in the printed image for the back side shown in FIG. 7B, the non-print area for adjusting the conveyance speed in step S22 and the area for printing the test pattern in step S24 are arranged in this order in the conveyance direction. Is done. The non-print area for adjusting the conveyance speed in step S22 and the area where the test pattern is printed in step S24 are laid out on the back surface of the area where the back surface adjustment pattern is printed in step S17. In other words, in step S17, it is required to adjust the conveyance speed in step S22 and print the back surface adjustment pattern having a length that sufficiently includes the area for printing the test pattern in step S24.

  As described above, according to the present embodiment, at the time of front side printing in the print position adjustment mode, the back side adjustment pattern having the same degree of duty as the actual image is printed together with the normal test pattern. As a result, it is possible to perform the adjustment for the back surface under the same conditions as those for actual image printing.

  In the above description, in the adjustment mode for the front surface, the test pattern is printed and then the back surface adjustment pattern is printed. However, the order is not particularly limited. In the adjustment mode for the back surface, it is only necessary to generate a situation in which the transport roller 30 is transporting the back surface adjustment pattern at the timing when the transport speed is adjusted or the test pattern is printed. The order may be reversed.

  In the above description, the duty of the back surface adjustment pattern is 50% as an example. However, of course, this value is not limited. For example, the duty may be set by the user. Also, a means for storing the print duty history of the actual image may be provided, and when executing the print position adjustment mode, the back surface adjustment pattern duty may be set according to the history so far. By adopting such a setting method, it is possible to adjust the print position in a state suitable for actual use by the user.

(Second Embodiment)
In the present embodiment, as in the first embodiment, the case where the printing apparatus 100 described with reference to FIGS. 2, 3, and 4 is used will be described. In the first embodiment, the back surface adjustment pattern is printed based on a duty set in a prescribed or some way, and the correction data corresponding to the duty is used as the second surface correction data for the back surface. On the other hand, in this embodiment, a plurality of correction data corresponding to a plurality of duties is obtained as the second surface correction data.

  FIG. 8 is a flowchart for explaining the steps executed by the CPU 201 of the control unit 13 when executing the print position adjustment mode in the present embodiment. Steps S1 to S16 are the same as those in the first embodiment. In subsequent step S30, the CPU 201 according to the present embodiment sequentially prints N back surface adjustment patterns having different duties in N stages.

  FIGS. 9A and 9B are views for explaining an image to be printed in the print position adjustment mode of the present embodiment while comparing it with FIGS. 7A and 7B. Referring to FIG. 9A, in this embodiment, after the non-print area and the front surface test pattern for adjusting the conveyance speed are arranged, N back surface adjustment patterns having different duties are continuously arranged. ing.

  Returning to the flowchart of FIG. When N back surface adjustment patterns are printed in step S30, the process proceeds to step S18, and the CPU 201 performs sheet reversal processing. That is, the CPU 201 cuts the continuous sheet at the position where the rear end of the back surface adjustment pattern printed in step S17 passes, conveys the sheet S to the reversing unit 9, and carries it back to the printing unit 4 with the front and back reversed. To do. Thereafter, in step S21, a preparation operation for back side printing is executed, and then an adjustment mode for the back side is entered.

  Subsequent steps S31 to S35 are routine processes repeated N times. In steps S31 and S32, the conveyance correction amount is obtained, the test pattern is printed in step S33, the test pattern is read in step S34, and the process of obtaining correction data in step S35 is repeated N times. Each routine is executed at a position corresponding to the back surface adjustment patterns having different duties, as shown in FIG. 9B. In step S35, correction data is stored in association with each duty.

  When the N back printing routines as described above are completed, the CPU 201 proceeds to step S27 and performs a sheet discharging operation. This completes the print position adjustment mode.

  FIG. 10 is a diagram showing the relationship between the duty of the back surface adjustment pattern and the correction value obtained by printing the test pattern on the back surface of each pattern. Here, N = 6, and the results of obtaining correction values for different six-stage duties are indicated by black circles. In this embodiment, such a jump correction value is stored in association with the duty. Then, from such a jump correction value, an approximate curve indicated by a solid line is obtained using a known method, and when performing an actual print operation, a correction value according to the print duty of the actual image printed on the surface Set. According to this embodiment as described above, it is possible to perform the adjustment for the back surface under appropriate conditions regardless of the print duty of the actual image.

  In the above description, the first surface correction data for the front surface and the second surface correction data for the back surface are obtained in one print position adjustment mode. However, the present invention is not limited to this. A print position adjustment mode for single-sided printing may be prepared independently of the above-described print position adjustment mode for double-sided printing, or a print position adjustment mode dedicated to the back side may be prepared. When a print position adjustment mode dedicated to the back side is prepared, a test pattern is not printed on the front side, only the back side adjustment pattern is printed, a reversal process is performed, and then a series of processes for back side adjustment is performed.

  Further, in consideration of the case where temperature and humidity change, the first surface correction data and the second surface correction data can be stored in association with a combination of temperature and humidity. In such a case, when printing an actual image, the print position can be adjusted according to the correction value corresponding to the combination closest to the temperature and humidity detected at the present time. Further, if an approximate curve as described with reference to FIG. 10 is obtained in advance based on correction data associated with a plurality of temperatures and a plurality of humidity, even if the environment changes variously, it is appropriate for both sides of the sheet. Correction processing can be performed.

  In the above description, the control unit of the printing apparatus executes the print position adjustment mode and manages and uses correction data for the printing apparatus. However, the present invention is not limited to such a form. Absent. For example, print driver software for controlling the printing apparatus is installed in the host apparatus 16 described with reference to FIG. 3, and the host apparatus controls various mechanisms of the printing apparatus according to a predetermined program, so that the above-described print position adjustment mode is performed. It can also be executed. In this case, the entire system including the host device and the printing device falls within the scope of the present invention.

  Furthermore, a process of supplying a program that realizes one or more functions of the above-described embodiment to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus reading and executing the program But it is feasible. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

  Furthermore, the present invention described above can be widely applied to printer multifunction devices, copiers, facsimile machines, various device manufacturing apparatuses, etc., in addition to the printing apparatus described above. Furthermore, various methods such as an ink jet method, an electrophotographic method, a thermal transfer method, a dot impact method, and a liquid developing method can be adopted as a printing method. Furthermore, the present invention is not limited to image print processing, but can be applied to various types of processing (printing, processing, application, irradiation, reading, inspection, etc.) on a sheet.

9 Reversing part
13 Control unit
14 Print head
30 Conveying roller 100 Printing device
S sheet

Claims (8)

A method for adjusting a print position for printing an image on both sides of a sheet,
In a state where the conveyance roller is conveying the sheet, a uniform adjustment pattern is printed on the first surface of the sheet using a print head,
The front and back surfaces of the sheet are reversed so that the second surface of the sheet faces the print head,
In a state where the conveyance roller conveys the sheet while contacting an area where the adjustment pattern is printed, a test pattern is printed on the second surface of the sheet using the print head,
Reading the test pattern, generating correction data for adjusting the print position of the print head on the second surface,
A method for adjusting a print position, wherein when printing an image on the second surface, the print position is adjusted using the correction data.   In a state where the conveyance roller conveys the sheet while contacting the area where the adjustment pattern is printed, the conveyance roller detects a conveyance speed by the conveyance roller, and generates correction data for controlling the conveyance roller. The print position adjusting method according to claim 1, wherein the print position is adjusted.   In a state where the conveyance roller conveys the sheet while contacting an area where an image is not printed, a test pattern is printed on the first surface of the sheet using the print head, and the test pattern is read. The print position adjustment method according to claim 1, wherein correction data for adjusting the print position of the print head on the first surface is generated.   The print position adjustment method according to claim 1, wherein the adjustment pattern is a uniform pattern having a predetermined duty.   5. The print position adjusting method according to claim 4, wherein the predetermined duty is set by a user or based on a print history of a printing apparatus.   2. The adjustment pattern according to claim 1, wherein the adjustment pattern is a plurality of uniform patterns having different duties, and the correction data on the second surface is generated corresponding to the different duties. 4. The method for adjusting a print position according to any one of items 3 to 3.   A program for causing a computer to execute the print position adjustment method according to any one of claims 1 to 6. A printing device that prints images on both sides of a sheet,
A conveying roller that contacts and conveys the sheet;
Means for printing a uniform adjustment pattern on the first surface of the sheet using a print head in a state where the conveyance roller is conveying the sheet;
Means for inverting the front and back surfaces of the sheet such that the second surface of the sheet faces the print head;
Means for printing a test pattern on the second surface of the sheet using the print head in a state where the conveyance roller conveys the sheet while being in contact with a region where the adjustment pattern is printed;
Means for reading the test pattern and generating correction data for adjusting the print position of the print head on the second surface;
A printing apparatus comprising:

Images