JP5464262B2 - Image forming apparatus - Google Patents

Description

  According to the present invention, a plurality of nozzles capable of discharging an image forming material by driving correspondingly provided driving elements correspond to the entire image formable range in a direction intersecting the conveyance direction of the image forming medium. The present invention relates to a formed image forming apparatus, and more particularly, to a control technology for a flushing operation in which a driving element is driven to discharge an image forming material from a nozzle.

  2. Description of the Related Art Conventionally, inkjet printers that form images by ejecting ink, which is an example of an image forming material, are known. As such an ink jet printer, printing is performed in the paper width direction by moving a carriage on which a head having a plurality of nozzles for ejecting ink is mounted in a direction perpendicular to the paper transport direction (paper width direction). Things are generally known.

  In such an ink jet printer, in order to prevent clogging of ink in the nozzle, deterioration of the ink, and the like, a flushing operation for ejecting ink from the nozzle regardless of printing is performed.

  For example, in an inkjet printer that prints by moving the head, the process of moving one or more lines by moving the head and the process of transporting the paper to the position to print the next line are executed alternately. . In such an ink jet printer, for example, the head is moved to a position outside the sheet after the process of printing one or more lines is finished and the process of conveying the sheet to the next printing position is completed. The flushing operation is performed at that position.

  Also, as an inkjet printer technology, each waveform pattern corresponding to each drive waveform mode consisting of startup, print, and end is stored in the storage unit, and the corresponding waveform pattern is selected according to the mode in printing. Is known (see, for example, Patent Document 1).

  By the way, as described above, the printer that prints by moving the head alternately executes the process of printing one or more lines by moving the head and the process of transporting the paper to the position for printing the next line. Therefore, there is a problem that the image forming speed is slow.

  Therefore, in recent years, a line ink jet printer that has a head module capable of ejecting ink over an entire row in the paper width direction and that can print in the paper width direction without moving the head has appeared.

JP 2001-187445 A

  In the above-described line ink jet printer, for example, printing is performed by controlling ejection of ink by each head while sequentially transporting sheets at a substantially constant speed.

  For this reason, the time during which the flushing operation can be performed is limited to the time from the end of the ejection of ink to a certain sheet to the start of the ejection of ink to the next sheet. For this reason, as compared with a printer that performs printing by moving the head, the time during which the flushing operation can be performed becomes extremely short.

  For example, after the printing is finished, the waveform data of the flushing waveform signal for performing the flushing operation is read into the memory, and the drive signal is generated based on the waveform data and supplied to the drive element, thereby performing the flushing operation. It takes a long time to finish, and there is a possibility that it may not be in time for printing on the next sheet.

  SUMMARY An advantage of some aspects of the invention is that a plurality of nozzles capable of ejecting an image forming material in correspondence with the entire area of an image formable range in a direction intersecting with a conveyance direction of an image forming medium. It is an object of the present invention to provide a technique capable of promptly executing a flushing operation in an image forming apparatus in which is formed.

In order to achieve the above object, in the image forming apparatus according to the first aspect of the present invention, a plurality of nozzles capable of ejecting an image forming material by driving a corresponding driving element are provided for conveying an image forming medium. In the image forming apparatus formed corresponding to the entire image formable range in the direction intersecting with the direction, the flushing waveform data representing the flushing waveform signal supplied to the driving element for performing the flushing operation, and the image forming operation Waveform data storage means for storing image forming waveform data representing the image forming waveform signal to be supplied to the drive element, and a waveform signal including the image forming waveform signal and the flushing waveform signal based on the image forming waveform data and the flushing waveform data Based on the waveform signal output means for generating and outputting the position of the image forming medium in the conveyance direction And determining means for determining whether or not it is a flushing operation time point, and when the determination means determines that it is the flushing operation time point, selecting the flushing waveform signal from among the waveform signals and According to the selective supply means for supplying to the driving element and the conveying speed of the image forming medium, the amount of deviation between the reference timing and the timing for outputting the waveform signal is grasped, and the generation timing for outputting the waveform signal is determined as described above. Timing adjustment means for adjusting the amount of deviation and notifying the waveform signal output means .

  According to the image forming apparatus, the waveform signal including the image forming waveform signal and the flushing waveform signal is generated and output based on the image forming waveform data and the flushing waveform data, and at the time of the flushing operation, the output waveform signal is output. By selecting the flushing waveform signal therein, the flushing waveform signal can be supplied to the driving element. For this reason, the flushing operation can be executed quickly.

  In the image forming apparatus, the image forming waveform signal includes a plurality of partial image forming waveform signals that enable execution of a plurality of image forming patterns, and the selection supply unit applies the image forming medium to the image forming medium at the time of image formation. Based on the image formation data indicating the image formation pattern to be formed, one or more partial image formation waveform signals corresponding to the image formation pattern may be selected from a plurality of partial image formation waveform signals and supplied to the drive element. Good. According to such an image forming apparatus, an image can be formed by selecting an appropriate image forming pattern from among a plurality of image forming patterns.

  Further, in the image forming apparatus, the selection supply unit includes a switch that opens and closes the circuit from the waveform signal output unit to the driving element, and the flushing waveform in the waveform signal when it is determined that the flushing operation time is reached. You may make it have a switch control means which controls a switch to a closed state so that a signal may be supplied to a drive element. According to such an image forming apparatus, the flushing waveform signal in the waveform signal can be easily and appropriately supplied to the drive element by controlling the opening and closing of the switch.

  The image forming apparatus may further include a timing adjusting unit that adjusts a generation timing for outputting the waveform signal in accordance with a conveyance speed of the image forming medium and notifies the waveform signal output unit of the generated timing. According to such an image forming apparatus, since the generation timing at which the waveform signal is output is adjusted according to the conveyance speed of the image forming medium, the image forming material can be ejected to an appropriate position.

  In the image forming apparatus, the waveform signal output unit outputs the waveform signal based on the notification of the timing at which the waveform signal is output from the timing adjustment unit, and notifies the selection supply unit of the timing at which the waveform signal is output. The selection supply unit may select the flushing waveform signal from the waveform signals based on the timing notified from the waveform signal output unit. According to such an image forming apparatus, it is possible to eject the image forming material to an appropriate position during the flushing operation.

  Further, in the above image forming apparatus, the waveform data storage means has a plurality of storage areas for storing the flushing waveform data, and the waveform signal output means changes each time the image forming medium to be image formed changes. The flushing waveform signal may be generated using the flushing waveform data stored in the storage area. According to such an image forming apparatus, when an image is formed on one image forming medium using data in one storage area, the waveform is used for image formation and flushing of another image forming medium in another storage area. The data can be used for subsequent processing by changing it according to various states. For this reason, image formation and flushing of each image forming medium can be appropriately performed according to the state.

  The image forming apparatus includes a transport unit that transports the image forming medium and a detection unit that detects a transport amount of the image forming medium by the transport unit, and the determination unit is based on the transport amount detected by the detection unit. Thus, the position in the conveyance direction of the image forming medium may be specified. According to such an image forming apparatus, it is possible to appropriately specify the position in the conveyance direction of the image forming medium and appropriately determine whether or not it is the time of the flushing operation.

1 is a partial side view of a printer according to an embodiment of the present invention. 1 is a partial top view of a printer according to an embodiment of the present invention. FIG. 2 is a functional configuration diagram of a printer according to an embodiment of the present invention. It is a figure explaining the timing adjustment of the waveform output which concerns on one Embodiment of this invention. It is a figure explaining the storage area in the waveform memory which concerns on one Embodiment of this invention. It is a figure explaining the printing waveform signal of the printer which concerns on one Embodiment of this invention, SI data, and SP data. It is a figure explaining the common waveform which concerns on one Embodiment of this invention. It is a figure explaining the command output by the waveform output part which concerns on one Embodiment of this invention.

  Embodiments of the present invention will be described with reference to the drawings. The embodiments described below do not limit the invention according to the claims, and all the elements and combinations described in the embodiments are essential for the solution of the invention. Is not limited.

  First, a line inkjet printer (also referred to as a printer) as an example of an image forming apparatus according to an embodiment of the present invention will be described.

  FIG. 1 is a partial side view of a printer according to an embodiment of the present invention, and FIG. 2 is a partial top view of the printer according to an embodiment of the present invention.

  The printer 1 is provided with a belt 2 that conveys an image forming medium (paper M) such as paper, an OHP sheet, and cloth supplied from a paper feed tray (not shown). The belt 2 is stretched over rollers 3a, 3b, and 3c of the paper transport unit 3, and is driven by a motor (not shown). When printing on the sheet M, the belt 2 conveys the sheet M from the sheet conveyance direction X, that is, from the upstream side (left side in FIG. 1) to the downstream side (right side in FIG. 1) at a substantially constant speed.

  The printer 1 can perform printing on a plurality of sizes of paper M. In the present embodiment, the printer 1 can print on paper M of various sizes up to a width W2 (maximum printable width) as shown in FIG. The printer 1 of the present embodiment is configured such that the approximate center of the sheet M in the sheet width direction Y is conveyed along the approximate center of the belt 2 in the sheet width direction Y regardless of the size of the sheet. If it is the paper M, it is conveyed so as to pass through the approximate center of the belt 2 as shown in FIG.

  Above the belt 2, an encoder 9 is provided so as to detect the movement amount of the belt 2 (corresponding to the conveyance amount of the paper M by the belt 2) so as to face the belt 2. In an area where the paper M of the belt 2 is not conveyed (near the lower end side in FIG. 2), an encoder pattern (not shown) is formed at regular intervals in the paper conveyance direction X. The encoder 9 irradiates the belt 2 with light, receives the reflected light from the belt 2, and outputs a signal corresponding to the light receiving state. When the belt 2 is driven, a pulse signal is output from the encoder 9 due to the difference in reflected light between the encoder pattern and a portion other than the pattern. According to this pulse signal, since the number of patterns that have passed can be grasped as the number of pulses, the amount of movement of the belt 2 can be grasped.

  In the printer 1, a plurality of head modules 4 (4A, 4B) are arranged in the paper transport direction X. The head module 4 has a plurality of heads 5. The head module 4 can be removed from the printer 1 and replaced with a similar head module, so that the printer 1 can be easily repaired.

  In the head 5, a plurality of nozzles 5 a that eject ink as an example of an image forming material are provided toward the side where the paper M is conveyed (lower side in FIG. 1). In the present embodiment, the head 5 is formed with a nozzle row in which a plurality of (for example, 180) nozzles 5a are arranged in the paper width direction Y (the depth direction in FIG. 1) perpendicular to the paper transport direction X, for example. The nozzle rows are formed in a plurality of rows (for example, 8 rows) in the paper transport direction X. For example, if the printer 1 performs printing with four colors of ink, two nozzle rows are assigned to each of yellow, magenta, cyan, and black, and the same color nozzle row is defined in the sheet width direction Y. The nozzles are arranged so that the positions of the nozzles are shifted by a predetermined amount (for example, half the nozzle pitch in the nozzle row). The head 5 is provided with a piezoelectric vibrator (drive element) 5b that expands and contracts according to the supplied drive signal so as to correspond to each nozzle 5a. By controlling the expansion and contraction of the piezoelectric vibrator 5b, The ejection of ink from the nozzle 5a can be controlled.

  As shown in FIG. 2, the head module 4 (4A, 4B) includes a head row in which a plurality of heads 5 are arranged in the paper width direction Y, and the head row is arranged in a plurality of rows (for example, The plurality of heads 5 are arranged in a staggered manner (alternately) in the paper width direction Y. The plurality of heads 5 in the first row (shown in order from the upstream side, hereinafter the same) are arranged along the paper width direction Y at a predetermined interval. Each of the plurality of heads 5 in the second row is a portion that cannot be printed by the head 5 in the first row in the entire image formable range (maximum printable width) in the sheet width direction Y (for example, the first row It is arranged so as to supplement printing between the heads 5). With the heads 5 in the first and second rows, ink can be ejected at a predetermined resolution (for example, 360 dpi) over the entire maximum printable width in the paper width direction Y.

  The first head module 4A (upstream head module) and the second head module 4B (downstream head module) have the same configuration, but the first head module 4A and the second head module 4B. Are arranged such that the positions of the corresponding nozzles are shifted in the paper width direction Y by a predetermined amount (for example, ¼ of the nozzle pitch in the nozzle row). As described above, since the positions of the corresponding nozzles of the first head module 4A and the second head module 4B in the paper width direction Y are shifted by a predetermined amount, the resolution over the entire maximum printable width is reduced to one head module. The resolution can be doubled (for example, 720 dpi).

  The printer 1 has a paper detection sensor 6. The paper detection sensor 6 is provided on the upstream side of the first head module 4A, and detects whether or not the paper M is present at a position on the belt 2 immediately below the first head module 4A. In the present embodiment, the paper detection sensor 6 detects the position of the belt 2 in the approximate center of the sheet width direction Y, that is, the position where the approximate center of the sheet M in the sheet width direction Y passes regardless of the size. Therefore, it is possible to appropriately detect whether or not the sheet M exists regardless of the size.

  The printer 1 is provided with a plurality of sprockets 8a, 8b, 8c, and 8d. A chain 7 is looped over the sprockets 8a, 8b, 8c, and 8d. A flushing sheet FLS that receives ink ejected from the nozzles 5 a of the head 5 at the time of flushing is attached to the chain 7. The flushing sheet FLS may be a member that does not absorb ink or may be a member that absorbs ink. In the present embodiment, flushing sheets FLS are mounted at three locations on the chain 7. As shown in FIG. 2, the chains 7 are provided at positions on both outer sides of the belt 5, and the flushing sheet FLS is attached to both the chains 7. A motor (not shown) is connected to the sprockets 8a, 8b, 8c and 8d, and the chain 7 and the flushing sheet FLS are driven in the clockwise direction in FIG. In the present embodiment, the flushing sheet FLS is driven so as to be positioned between the paper M conveyed on the belt 2 and the next paper M in the next order.

  Next, the functional configuration of the printer 1 will be described.

  FIG. 3 is a functional configuration diagram of the printer according to the embodiment of the present invention.

  The printer 1 includes a plurality of head modules 4 (4A, 4B), an encoder 9, a communication interface unit (communication I / F unit) 11, a RAM (Random Access Memory) 12, a ROM (Read Only Memory) 13, and the like. And a control unit 14 and a head drive circuit 15.

  The communication I / F unit 11 mediates exchange of print data and the like between a host device (not shown) and the control unit 14.

  The RAM 12 is used as an area for storing programs and data, or as a work area for storing data used for processing by the control unit 14. In the present embodiment, the RAM 12 stores print data received from a host device (not shown). As print data, for example, SI data corresponding to the gradation value of each pixel in an image to be printed, and a drive pulse (partial image forming waveform signal) in a print waveform signal to be selected corresponding to each gradation, which will be described later. SP data is shown. In this embodiment, the SI data represents each pixel with a gradation value of 1 to 4, and is 2-bit data for each pixel. Details of SI data and SP data will be described later. The ROM 13 stores various programs such as a boot program executed by the control unit 14.

  The control unit 14 controls operations of the units 11, 12, 13, and 15. For example, the control unit 14 receives print data from a host device (not shown) via the communication I / F unit 11 and stores it in the RAM 12. Further, the control unit 14 controls the moving speed of the belt 2 by controlling the motor of the paper transport unit 3. Further, the control unit 14 controls the drive of the chain 7. In addition, the control unit 14 reads SI data and SP data from the RAM 12 and passes them to the head drive circuit 15.

  The head drive circuit 15 includes a state management unit 21 as an example of a determination unit, a waveform output unit 22 as an example of a waveform signal output unit, a timing adjustment unit 23 as an example of a timing adjustment unit, and an example of a switch control unit. As a command analysis unit 24 and an output selection unit 25. Here, the selection supply unit includes a command analysis unit 24 and an output selection unit 25. In the present embodiment, the command analysis unit 24 and the output selection unit 25 are configured by hardware circuits.

  The state management unit 21 receives the signal from the encoder 9 and counts the number of pulses in the signal from a predetermined time (for example, the time when the paper M is detected by the paper detection sensor 6), and based on the number of pulses, each piezoelectric vibration is counted. The operation state to be executed is grasped by the child 5b, and the designation of the waveform to be output is notified to the waveform output unit 22. For example, the state management unit 21 may grasp the operation state for each nozzle 5a of each head 5, and operates for each of a plurality of nozzles 5a arranged in the sheet conveyance width Y direction in the same operation state. You may make it grasp | ascertain a state. In the present embodiment, the state management unit 21 grasps whether it is a printing operation time point, a flushing operation time point, or another state, and designates a waveform corresponding to the grasped state as a waveform output unit 22. Notify The state management unit 21 also designates a storage area in which waveform data used for generating a waveform is stored. In the present embodiment, the state management unit 21 designates that a waveform is generated using waveform data in a different storage area each time the target paper M changes.

  The timing adjustment unit 23 receives a signal from the encoder 9 and, based on the frequency of occurrence of pulses in this signal, determines the amount of deviation between the timing at which the waveform output unit 22 should output the signal and the rise of the pulse signal of the encoder 9. To grasp. In addition, the timing adjustment unit 23 sends a signal indicating that a predetermined waveform signal should be output as a drive signal to the waveform output unit 22 when the grasped amount of deviation has elapsed from the rising edge of the pulse signal of the encoder 9. Notice.

  Here, adjustment of waveform output timing by the timing adjustment unit 23 will be described.

  FIG. 4 is a diagram for explaining timing adjustment of waveform output according to an embodiment of the present invention.

  4A shows a signal of the encoder 9 when the paper M is being conveyed at a constant speed, and FIG. 4A-1 shows a predetermined signal output by the waveform output unit 22 based on the rising edge of the pulse of the encoder 9. FIG. 4B shows an example of a signal supplied to the piezoelectric vibrator 5b when the output of the waveform signal is started. FIG. 4B shows a signal of the encoder 9 when the conveyance speed of the paper M changes. 4 (b-1) shows an example of a signal supplied to the piezoelectric vibrator 5b when the waveform output unit 22 starts outputting a predetermined waveform signal based on the rising edge of the pulse of the encoder 9, and FIG. (B-2) is supplied to the piezoelectric vibrator 5b when the waveform output unit 22 starts to output a predetermined waveform signal based on the timing when the timing of the pulse of the encoder 9 is adjusted. Shows an example of the signal .

  As shown in FIG. 4A, when the sheet M is conveyed at a constant speed, the signal from the encoder 9 rises at a constant interval. Accordingly, when a predetermined waveform signal is output by the waveform output unit 22 on the basis of the rise of the pulse of the signal from the encoder 9, for example, as shown in FIG. Since the correspondence relationship with the signal W is kept substantially constant, the reference position and the position at which ink is ejected can be made a substantially constant distance.

  On the other hand, as shown in FIG. 4B, when the transport speed of the paper M is decreased, the pulse from the signal from the encoder 9 does not rise at regular intervals. In the case of the figure, the pulse rising interval becomes long. In such a case, when a signal is output by the waveform output unit 22 with reference to the rise of the pulse, as shown in FIG. 4B-1, the correspondence between the transport distance D and the signal W for ejecting ink is obtained. It depends on the case. For example, when the conveyance speed of the paper M is slowed down, the conveyance amount of the paper M during the output of the signal W is reduced. For this reason, as the conveyance speed of the sheet M becomes slower, the ink is ejected near the reference position corresponding to the rising of the pulse, and the position where the ink is ejected varies.

  On the other hand, in this embodiment, as shown in FIG. 4B-2, the waveform output unit 22 performs a predetermined waveform signal on the basis of the timing when the timing adjustment unit 23 performs timing adjustment from the reference position. Therefore, when the same waveform signal is supplied, ink can be ejected at a substantially constant distance from the reference position regardless of the conveyance speed of the paper M.

  The waveform output unit 22 includes a waveform memory 26 that stores waveform data for generating various waveform signals.

  FIG. 5 is a diagram for explaining a storage area in the waveform memory according to the embodiment of the present invention.

  The waveform memory 26 has a non-printing fine vibration A surface 27A and a non-printing fine vibration B surface 27B as a plurality of storage areas for storing waveform data at a time point different from the printing time point and the flushing time point (non-printing time point). And. Non-printing fine vibration A surface 27A and non-printing fine vibration B surface 27B store non-printing fine vibration waveform data, respectively. It should be noted that a waveform necessary at the time of printing can be generated by using one of the non-printing fine vibration waveform data on the non-printing fine vibration A surface 27A or the non-printing fine vibration B surface 27B.

  The waveform memory 26 includes a printing A surface 28A and a printing B surface 28B as a plurality of storage areas for storing waveform data at the time of printing. On each of the printing A surface 28A and the printing B surface 28B, startup waveform data which is startup waveform data at the time of printing, pre-printing fine vibration waveform data which is fine vibration waveform data, and Print waveform data that is waveform data used for actual printing and end-down waveform data that is end-down waveform data are stored. It should be noted that a waveform required at the time of printing can be generated by using the waveform data of either the printing A surface 28A or the printing B surface 28B.

  The waveform memory 26 includes a flushing A surface 29A and a flushing B surface 29B as a plurality of storage areas for storing waveform data at the time of flushing. Each of the flushing A surface 29A and the flushing B surface 29B includes startup waveform data that is startup waveform data at the time of flushing, and pre-FL microvibration waveform data that is microvibration waveform data before flushing, FL waveform data that is waveform data used for actual flushing operation and end-down waveform data that is end-down waveform data are stored. A waveform required at the time of flushing can be generated by using waveform data of either the flushing A surface 29A or the flushing B surface 29B.

  Here, a print waveform signal (image forming waveform signal) generated based on the print waveform data by the waveform output unit 22 will be described, and SI data and SP data will be described together.

  FIG. 6 is a diagram for explaining a print waveform signal, SI data, and SP data in a printer according to an embodiment of the present invention, FIG. 6A is a diagram for explaining a print waveform signal, and FIG. 6B is a diagram for explaining SI data. FIG. 6C is a diagram for explaining the configuration of transmitted SI data and SP data.

  The print waveform signal generated based on the print waveform data by the waveform output unit 22 has a plurality of drive pulses (partial image forming waveform signals). In the present embodiment, as shown in FIG. 4A, the print waveform signal includes a first drive pulse P1, a second drive pulse P2, a third drive pulse P3, and a fourth drive pulse P4. In the present embodiment, the first drive pulse P1 and the third drive pulse P3 have similar waveforms.

  In the present embodiment, by selecting a drive pulse to be supplied to the piezoelectric vibrator 5b from among the plurality of drive pulses P1 to P4, it is possible to eject ink droplets having a plurality of sizes. That is, an image having a plurality of patterns can be formed.

  When the first drive pulse P1 is supplied to the piezoelectric vibrator 5b, for example, 13 pl of ink is ejected from the corresponding nozzle 5a, and medium dots are formed on the paper M. When the second drive pulse P2 is supplied to the piezoelectric vibrator 5b, for example, 6 pl of ink is ejected from the corresponding nozzle 5a to form a small dot. Further, when the third drive pulse P3 is supplied to the piezoelectric vibrator 5b, for example, 13 pl of ink is ejected from the nozzle 5a to form a medium dot. When the fourth drive pulse P4 is supplied to the piezoelectric vibrator 31, the piezoelectric vibrator 5b vibrates slightly, but no ink is ejected from the corresponding nozzle 5a, and no dots are formed on the paper M.

  The correspondence between the SI data for one pixel and the selected drive pulse is as shown in FIG. 6B. That is, in the case of the gradation value 1 corresponding to no dot (00 in SI data), only the fourth drive pulse P4 is selected. Further, in the case of the gradation value 2 (01 in SI data) corresponding to the small ink dot, only the second drive pulse P2 is selected. Thereby, a small dot is formed. When the gradation value is 3 (10 in SI data) corresponding to the ink dot, only the first drive pulse P1 is selected. As a result, medium dots are formed. Further, in the case of the gradation value 4 (11 in SI data) corresponding to the large ink dot, the first drive pulse P1 and the third drive pulse P3 are selected. As a result, medium dots are ejected twice to form large dots.

  In this embodiment, as shown in FIG. 6B, the correspondence between each gradation value of SI data and the drive pulse selected for each gradation value is “1” for the selected drive pulse, and “ 0 ”, from the position corresponding to the maximum gradation value of the fourth drive pulse P4 (TOP) to the position corresponding to the first gradation value of the first drive pulse P1 (BOTTOM) according to the order of the arrows in the drawing. It is indicated by data arranged in order (SP data). In the case of the correspondence shown in FIG. 6B, the SP data is 16-bit data “0001100000101100” as shown in FIG. 6C.

  The waveform output unit 22 generates and outputs a signal for each piezoelectric vibrator 5 b including a waveform designated by the state management unit 21 based on the waveform data of the waveform memory 26 using a predetermined signal as a trigger. The signal for each piezoelectric vibrator 5b may be different depending on the position of each piezoelectric vibrator 5b in the paper transport direction X and the like. In the present embodiment, the waveform output unit 22 acquires waveform data of a specified waveform from the storage area specified by the state management unit 22 using a signal indicating that the output timing is from the timing adjustment unit 23 as a trigger. Then, a drive signal is generated based on the waveform data, and is output to the output selection unit 25 so as to be supplied to each piezoelectric vibrator 5b.

  In the present embodiment, the waveform output unit 22 outputs a drive signal including a waveform at the time of printing and a waveform at the corresponding flushing time when a waveform at the time of printing or flushing is designated. For example, when the waveform designated by the state management unit 21 is a printing startup waveform or a flushing startup waveform, the waveform output unit 22 includes a printing startup waveform and a flushing startup waveform. When the waveform specified by the state management unit 21 is a print waveform or a flushing waveform, a waveform signal including the print waveform signal and the flushing waveform signal is generated and output.

  FIG. 7 is a diagram illustrating an output waveform according to an embodiment of the present invention.

  When the print waveform or the flushing waveform is designated, the waveform output unit 22 has a first drive pulse P1, a second drive pulse P2, a third drive pulse P3, and a fourth drive pulse P4 as shown in FIG. Subsequently to the print waveform signal including, a flushing waveform signal (FL waveform signal) including the FL drive pulse P5 is output. In the present embodiment, the FL drive pulse P5 of the flushing waveform signal is different from any drive pulse of the print waveform signal, but may have the same shape as any drive pulse.

  The waveform output unit 22 transmits a command indicating a waveform signal to be selected from among the drive signals to the command analysis unit 24 with a signal indicating that the output timing is from the timing adjustment unit 23 as a trigger. In the present embodiment, the transmission timing of this command corresponds to the timing of outputting a predetermined waveform by the waveform output unit 22.

  FIG. 8 is a diagram for explaining a command output by the waveform output unit according to the embodiment of the present invention.

  FIG. 8 shows designation of a storage area (memory area designation) used for generating waveform data notified from the state management unit 21 and designation of a waveform to be selected for supply to the piezoelectric vibrator 5b (waveform designation). ) And a command (output command) to be output to the command analysis unit 24.

  For example, when the waveform output unit 22 receives a notification from the state management unit 21 that the memory area designation is not selected and the waveform designation is not selected, the waveform output unit 22 outputs the output command as the output command. A command (“00”) indicating that a signal to be supplied to the piezoelectric vibrator 5b is not selected from the drive signal is transmitted. When the waveform output unit 22 receives notification of “printing A side” or “printing B side” as the memory area designation, the waveform output unit 22 prints out of the drive signals output from the waveform output unit 22. A command (“01”) that means selecting the waveform signal is transmitted. Further, when the waveform output unit 22 receives a notification of “flushing A side” or “flushing B side” as the memory area designation, the waveform output unit 22 uses the flushing drive signal output from the waveform output unit 22 for flushing. A command (“10”) that means selection of a waveform signal is transmitted.

  The command analysis unit 24 receives the command from the waveform output unit 22, and selects the output selection unit 25 based on the command reception timing so as to select the waveform corresponding to the command from the drive signal output from the waveform output unit 22. Control. In this embodiment, since the output selection unit 25 is controlled based on the command reception timing, a desired portion of the signal output by the waveform output unit 22 is appropriately selected and supplied to the piezoelectric vibrator 5b. can do. Therefore, ink can be ejected to an appropriate position. That is, at the flushing time, ink can be ejected to a predetermined position of the flushing sheet FLS.

  In the present embodiment, when the command analysis unit 24 receives a command meaning that a waveform signal for printing is selected, an output selection is performed so that the waveform signal for printing is selected based on the reception timing of the command. When the control unit 25 is controlled and a command that means selecting a waveform signal for flushing is received, the output selection unit 25 is selected so that the waveform signal for flushing is selected based on the reception timing of the command. Control. For example, when a waveform signal including a print waveform signal and a flushing waveform signal is output from the waveform output unit 22 and the command analysis unit 24 receives a command indicating that a waveform signal for printing is received. Controls the output selection unit 25 based on the reception timing of the command so as to select the drive pulse corresponding to the gradation value of the SI data of each pixel in the print waveform signal of the waveform signal. Further, when the command analysis unit 24 receives a command that means selecting a flushing waveform signal, the command reception timing is used as a reference so that the FL driving pulse P5 of the flushing signal in the common waveform is selected. The output selection unit 25 is controlled.

  Here, with respect to the print waveform signal, a process of selecting a drive pulse to be supplied to the piezoelectric vibrator 5b from a plurality of drive pulses of the print waveform signal is performed, so that the drive pulse of the print waveform signal includes the FL drive pulse. It is also conceivable to perform the process of selecting the above. However, if the selection process including the FL driving pulse is performed, it is necessary to increase the gradation value indicating the FL driving pulse by one. As a result, the gradation value data corresponding to one nozzle is necessary. The bit is changed from 2 bits to 3 bits. As a result, the data (SI data) for all the nozzles has a considerable amount of data, which causes a problem that it takes time to transfer data and a problem that the amount of memory required increases. Therefore, in the present embodiment, as described above, the selection of the flushing waveform signal is performed based on the command.

  The output selection unit 25 includes, for example, a plurality of switches, and closes or opens each circuit between the waveform output unit 22 and each piezoelectric vibrator 5b in accordance with control by the command analysis unit 24. . When the switch circuit of the output selection unit 25 is closed, the drive signal input from the waveform output unit 22 is supplied to the corresponding piezoelectric vibrator 5b of the head 5, and the piezoelectric vibrator 5b is driven. The On the other hand, when the switch circuit of the output selection unit 25 is opened, the drive signal input from the waveform output unit 22 is not supplied to the corresponding piezoelectric vibrator 5 b of the head 5.

  Next, a printing process according to an embodiment of the present invention will be described.

  When the sheet M is being conveyed on the belt 2 by the sheet conveying unit 3, the encoder 9 outputs a signal corresponding to the driving of the belt 2. The state management unit 21 acquires a signal from the encoder 9, and based on the number of pulses included in the signal, whether each nozzle 5a of each head 5 is at the time of printing on the paper M or at the time of flushing. , Or any other time, and which signal should be supplied.

  Here, for the sake of explanation, the operation will be described by paying attention to a certain nozzle 5a (referred to as a target nozzle) among the plurality of nozzles 5a. The same operation is performed for nozzles other than the target nozzle.

  As a result of the determination by the state management unit 21, when it is determined that the print waveform signal for actually ejecting ink should be supplied to the nozzle of interest at the time of printing, the state management unit 21 uses one for printing Are designated (for example, a memory area different from the memory area used when printing the immediately preceding paper M), and a notification for designating the print waveform is sent to the waveform output unit 22.

  On the other hand, the timing adjustment unit 23 acquires a signal from the encoder 9, and according to the generation frequency of pulses included in the signal, the timing at which the waveform output unit 22 should output the signal and the rise of the pulse signal of the encoder 9 The waveform output unit 22 receives a signal indicating that the designated waveform signal should be output as a drive signal when the detected amount of deviation has elapsed from the rising edge of the pulse signal of the encoder 9. Notice.

  The waveform output unit 22 generates a waveform signal including a print waveform signal and a flushing waveform signal based on the signal from the timing adjustment unit 23 and outputs it as a signal for the piezoelectric vibrator 5a corresponding to the target nozzle. And a command indicating that a waveform signal for printing is selected is transmitted to the command analysis unit 24.

  Based on the timing at which the command is received, the command analysis unit 24 selects a drive pulse corresponding to the SI data from the print waveform signals among the common waveform signals and supplies the selected drive pulse to the piezoelectric vibrator 5b of the nozzle of interest. Thus, the output selection unit 25 is controlled. As a result, ink droplets corresponding to the gradation values are ejected from the nozzle of interest, and desired printing is performed. The same processing as described above is executed until the state management unit 21 determines that the target nozzle is at the flushing time.

  When the state management unit 21 determines that the nozzle of interest is at the flushing time, the state management unit 21 notifies the waveform output unit 22 of a notification for designating the flushing waveform signal.

  On the other hand, the timing adjustment unit 23 acquires a signal from the encoder 9, and according to the frequency of pulses included in the signal, the timing at which the waveform output unit 22 should output the signal and the rise of the pulse signal of the encoder 9 The amount of deviation is grasped, and when the grasped amount of deviation elapses from the rising edge of the pulse signal of the encoder 9, a signal indicating that a predetermined waveform signal should be output as a drive signal is notified to the waveform output unit 22. .

  The waveform output unit 22 generates a common waveform signal including a print waveform signal and a flushing waveform signal based on the signal from the timing adjustment unit 23 and outputs it as a signal for the piezoelectric vibrator 5a corresponding to the target nozzle. A command indicating that the waveform signal for flushing is selected is transmitted to the command analysis unit 24.

  The command analysis unit 24 controls the output selection unit 25 so that the flushing waveform signal in the common waveform signal is selected and supplied to the piezoelectric vibrator 5b of the nozzle of interest based on the timing at which the command is received. As a result, ink droplets for flushing are ejected from the target nozzle. In the present embodiment, when the printing operation is changed to the flushing operation, it is not necessary to write the flushing waveform data to the waveform memory 26, and only the waveform signal selected by the command analysis unit 24 is switched to quickly change from the printing operation to the flushing operation. You can switch to That is, the flushing operation can be started quickly. Accordingly, it is possible to shorten the distance between the transported sheets M to be flushed, increase the transport speed of the sheets M, and improve the printing efficiency.

  Further, in the present embodiment, when switching from the flushing operation to the printing operation, it is possible to quickly switch by the process similar to the above, and it is possible to start the printing operation quickly.

  Although the present invention has been described based on the embodiments, the present invention is not limited to the above-described embodiments, and can be applied to various other modes.

  For example, in the above embodiment, when the printing operation is performed, the common waveform signal including the printing waveform signal and the FL waveform signal is sequentially generated. However, the present invention is not limited to this. For example, the flushing is performed. A common waveform signal including the FL waveform signal may be generated when the operation is performed or immediately before the operation is performed.

  Further, in the above-described embodiment, the print waveform signal includes a plurality of partial waveform signals, and a plurality of sizes of ink droplets can be selected and ejected by selecting the partial waveform signal as a unit. However, the present invention is not limited to this, and the print waveform signal may be a waveform signal for ejecting ink droplets of a predetermined size.

  In the above embodiment, the head module 4 (4A, 4B) is configured to print only a part of the maximum printable width in order to print the entire image formable range (maximum printable width) in the paper width direction. A plurality of printable heads are provided, and these heads are arranged to allow printing of the entire maximum printable width. However, the present invention is not limited to this, and the entire maximum printable width can be printed. One head, that is, one head having a plurality of nozzles arranged so as to print the entire maximum printable width may be provided.

  In the above embodiment, the two head modules 4A and 4B are provided in the paper conveyance direction. However, the present invention is not limited to this, and three or more head modules 4 may be provided in the paper conveyance direction. Good. In the above embodiment, a single head module 4 ejects a plurality of colors of ink. However, the present invention is not limited to this. For example, one head module ejects a predetermined color of ink. In this case, a plurality of head modules having different ink colors may be provided.

  In the above embodiment, a line inkjet printer has been described as an example of the image forming apparatus. However, the present invention is not limited to this, and an image forming apparatus that ejects a liquid other than ink or a powdery substance such as toner is used. The present invention can also be applied to an image forming apparatus that flies.

  1 line inkjet printer, 2 belt, 3 paper transport unit, 3a, 3b, 3c roller, 4 head module, 4A first head module, 4B second head module, 5 head, 5a nozzle, 5b piezoelectric vibrator, 6 paper detection Sensor, 7 Chain, 8a, 8b, 8c, 8d Sprocket, 9 Encoder, 11 Communication I / F section, 12 RAM, 13 ROM, 14 Control section, 15 Head drive circuit, 21 State management section, 22 Waveform output section, 23 Timing adjustment unit, 24 command analysis unit, 25 output selection unit, 26 waveform memory, FLS flushing sheet, M paper.

Claims (5)

A plurality of nozzles capable of ejecting an image forming material by driving the moving element driving is, in the image forming apparatus which is formed corresponding to the entire region in the direction of the image forming range intersecting the transport direction of the image forming medium,
Waveform data storage for storing flushing waveform data representing a flushing waveform signal supplied to the driving element for performing a flushing operation and image forming waveform data representing an image forming waveform signal supplied to the driving element for performing an image forming operation Means,
Waveform signal output means for generating and outputting a waveform signal including an image forming waveform signal and a flushing waveform signal based on the image forming waveform data and the flushing waveform data;
Determining means for determining whether or not it is a flushing operation time point for performing a flushing operation based on a position of the image forming medium in the conveyance direction;
A selection supply means for selecting the flushing waveform signal in the waveform signal and supplying the same to the drive element when the determination means determines that it is the time of the flushing operation;
Timing adjustment means for adjusting a deviation amount between a generation timing at which the waveform signal should be output and a reference timing according to a conveyance speed of the image forming medium and notifying the waveform signal output means ; apparatus. The image forming waveform signal includes a plurality of partial image forming waveform signals that enable execution of a plurality of image forming patterns,
The selection supply means is one or more corresponding to the image formation pattern from a plurality of partial image formation waveform signals based on image formation data indicating an image formation pattern to be formed on the image formation medium at the time of the image formation. The image forming apparatus according to claim 1, wherein the partial image forming waveform signal is selected and supplied to the driving element. The selective supply means includes
A switch for opening and closing a circuit from the waveform signal output means to the drive element;
2. Switch control means for controlling the switch to a closed state so that the flushing waveform signal in the waveform signal is supplied to the drive element when it is determined that the flushing operation time is reached. Alternatively, the image forming apparatus according to claim 2. The waveform signal output means outputs the waveform signal based on the notification of the generation timing from the timing adjustment means, and notifies the selection supply means of the timing for outputting the waveform signal,
4. The image formation according to claim 1 , wherein the selection supply unit selects the flushing waveform signal from the waveform signals based on the timing notified from the waveform signal output unit. apparatus. Conveying means for conveying the image forming medium;
Detecting means for detecting a transport amount of the image forming medium by the transport means;
Said determination means on the basis of the said conveying amount detected by the detecting means, the image forming apparatus according to any one of claims 1 to 4 for identifying the position of the conveying direction of the image forming medium .

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