JP2006130830A - Line dot recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a line dot recording device that moves a printing medium with a rotating drum, overcomes a decrease (lengthening of time) in a throughput (printing time per sheet) when an image is formed in a prescribed printing area of the medium by multi-pass dot recording and efficiently forms a high quality image on a plurality of printing mediums. <P>SOLUTION: The line dot recording device A is provided with a nozzle head 1 having a recording element using many inkjet ink discharge openings (nozzles) as a recording head, a rotary drum 2, the outside periphery of which is provided close thereto, a paper feeding means 3 feeding papers to the drum, a mounting/holding means 4 mounting and holding the four sheets of papers on the drum, and a paper delivery means 5 delivering the papers. By rotating the drum at four times the speed by a four-pass multi-pass method in a sub-scanning direction, the recording device forms an image by four rotations, solves a decrease in a throughput, and obtains a high quality image. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a line dot recording apparatus that efficiently prints on a printing medium (paper) attached to a peripheral surface of a rotating body by ink jet recording dots in which recording elements having a plurality of ink ejection openings are arranged in a line.

  As a method of forming and printing an image on a printing medium (paper) by spraying droplets with an ink jet head, an ink jet type recording head having a plurality of ink jet nozzles (ejection ports) on a carriage is provided reciprocally. A so-called serial printing method in which the ink jet head is moved and scanned in the width direction (main scanning direction) of the paper (standard size) of the print medium, and the paper is advanced little by little in the orthogonal direction (sub scanning direction), and ink jet recording There is a line printing method in which ink jet nozzles corresponding to one line portion (one line) of paper are arranged in a line on the head, the head is placed in a stationary state, and recording is performed while scanning in the paper feed direction.

  Of these, line-print printers are capable of high-speed printing, and are employed in, for example, on-demand inkjet line printers. Of course, in the serial printing method, even in the inkjet recording method by the inkjet line printer, the multi-pass method dot recording method for recording the image thinned out in a plurality of times with a little delay has already been generally adopted. Various proposals have been made in order to prevent the image quality from being deteriorated due to uneven density or ink bleeding on the paper and to improve the image quality at the time of image formation.

  As a cause of image quality deterioration due to density unevenness or bleeding, the ink discharge volume (amount) and direction from the ink discharge port (nozzle), which is a recording element in an inkjet line printer, vary depending on the individual ink discharge port. Variation occurs in dot size and dot position. Such variation in dot positions results in non-uniform distances between adjacent dots, high density in close locations, low density in remote locations, and sometimes white streaks, resulting in image quality degradation. In addition, the variation in dot size results in a difference in density between adjacent dots, which is recognized as a streak pattern and causes deterioration in image quality.

  As a dot recording method for preventing such image quality deterioration, Japanese Patent Laid-Open No. 10-138520 discloses a conventional dot recording method (Japanese Patent Laid-Open No. 10-138520) that performs dot recording (printing) of necessary pixels by two or four rotations of a rotating drum. Explains the method. In the method of printing with two rotations of the rotating drum, a number of jet nozzles corresponding to the prescribed number of pixels in the main scanning direction (each row) to be printed on the paper mounted on the rotating drum are arranged in the main scanning direction, In the main scanning direction, dot recording is performed with one rotation of the rotating drum for each row on the paper that moves with the rotation of the rotating drum with nozzles arranged in every other row, and then dots are recorded between the remaining columns with the second rotation of the rotating drum. And printing.

  In addition, the dot recording method with four rotations of the rotating drum is such that, on the paper mounted on the rotating drum, in the first rotation of the drum, every other dot in the main scanning direction (each row direction) and in the sub-scanning direction (each column direction). Also, every other dot is recorded, and in the second rotation, dots are recorded in a checkered pattern in the middle of every other dot. In this recording method, dots are recorded and all pixels are recorded by four rotations of the rotating drum. Such a dot recording method can delay each ink drying time until dot recording (printing) is performed for all adjacent dots after each dot recording, which is one step higher than a means for increasing the printing speed. It is said to be suitable for image quality printing.

  In Patent Document 2, the recording head is arranged so as to be movable in the direction in which the recording elements are arranged, that is, in the main scanning direction, and jet nozzle discharge ports as recording elements are provided at a pitch that is, for example, twice that of the pixel to be recorded. Dot recording is performed at the first rotation of the rotating drum at a thinning interval of 1 dot in the main scanning direction and at a thinning interval of 1 dot in the sub-scanning direction, and the recording head is moved by 1 dot at the second rotation of the rotating drum. A dot recording method is disclosed in which dot recording is performed and the recording setting position with respect to the basic resolution of the dots is shifted between the odd and even lines in the main scanning line. In this dot recording method, it is said that the occurrence of streaky density unevenness can be effectively reduced in printing that requires intermediate gradation.

  On the other hand, Patent Document 3 discloses a dot recording method by multi-pass printing in a so-called serial printing type jet nozzle printer. In this dot recording method, a plurality of jet nozzle ejection openings of the recording element are arranged in a direction orthogonal to the scanning direction of the carriage that moves in the width direction of the recording medium. In this dot recording method, various multi-pass double-speed printing lines from 2-pass double-speed printing to 4-pass quad-speed printing are shown. In this method, it is possible to perform double speed or quadruple speed printing by setting the scanning speed in the second recording mode faster than the scanning speed in the first recording mode.

  However, the dot recording methods according to Patent Documents 1 and 2 described above are multipass dot recording systems based on drum rotation and arranged with a plurality of jet nozzles in the main scanning direction, but mainly focus on preventing image quality degradation. For example, dot recording is performed with a little delay in the remaining pixel portion passed by two or four rotations of the rotating drum, and the purpose is to prevent density unevenness and ink bleeding. Do not print with dot recording.

  On the other hand, Patent Document 3 discloses a dot recording method for multipass printing in a serial printing method, and for example, high-speed printing such as double speed or quadruple speed in the main scanning direction is possible. However, the serial printing method is a method in which an inkjet nozzle head held by a carriage is moved and scanned to perform dot recording, and the nozzle head is provided with a predetermined number of ejection openings, but the nozzle head length is Since the length is limited to a fraction of the paper width, the number of ejection ports is plural, but it is not possible to provide as many ejection ports as a line printer. Therefore, high-speed printing is attempted at 2 × or 4 × speed.

  Therefore, even if it is assumed that the multipass dot recording method in the serial printer is applied to the multipass dot recording method using the rotary drum type line printer, the serial printer cannot be applied as it is because it is not the rotary drum type. Further, only one sheet is mounted on the rotary drum of the line printer according to Patent Documents 1 and 2, and dot recording cannot be performed continuously and efficiently on a plurality of sheets.

  The reason why the multipass dot recording method in the serial printer described above cannot be applied to a rotary drum line printer is that, as described above, in the serial printer, the nozzle head is printed at a high speed of 2 × or 4 × in the main scanning direction. However, if a clear image is formed by increasing the number of passes in the multi-pass method, the number of scans of the nozzle head increases, and the throughput (printing time per sheet) becomes very long accordingly. On the other hand, a rotary drum line printer is intended to print a large amount of printed matter at high speed, and thus a method with such a long throughput cannot be used for high-speed printing as it is.

  If the scanning speed of the nozzle head carriage is increased with a serial printer in order to prevent a decrease in throughput, the carriage movement will be extremely high, and the acceleration and deceleration at both ends of the movement will be extremely large, A mechanical structure that can withstand deceleration is required. As a result, the size of the apparatus is increased, and the manufacturing cost is increased to increase the strength and accuracy. If the strength and accuracy are the same, the durability is reduced. In addition, since an area for acceleration / deceleration of carriage movement is required, stroke areas that do not directly contribute to image formation are necessary at both ends of the stroke necessary for actual image formation. However, increase the scanning speed to reduce acceleration. Then, the stroke of this part will become remarkably large.

  Furthermore, as acceleration / deceleration increases at both ends of the carriage movement, there is a problem in smooth ink supply from the ink chamber in the nozzle head to the nozzles, or the carriage moves at high speed and is accelerated / decelerated. Of course, the inconvenience that the vibration and noise of the apparatus increase is expected. Accordingly, the nozzle heads arranged in a line are not moved or moved at a low speed that does not cause such various inconveniences, and at a high speed such as double speed or quadruple speed in the sub-scanning direction. Although it is conceivable to apply a multipass dot recording method to a plurality of sheets mounted on a rotating drum, there has been no example of such a trial yet.

In addition, although the general configuration is the same as that of the apparatus that mounts a plurality of sheets of paper in the sub-scanning direction in such a sub-scanning direction and performs dot recording with multipass and multiple rotations, the dot recording method at a high speed as described above. In addition, an apparatus that records dots at a predetermined speed or less can be considered.
JP 2001-18374 A Japanese Patent Laid-Open No. 11-115220 JP-A-4-366645

  With this invention in mind, the throughput (printing time per sheet) that occurs when a printing medium is moved by a rotating drum and an image is formed by multipass dot recording in the predetermined printing area is reduced. It is a first object to provide a line dot recording apparatus that eliminates (longer time) and can efficiently form high-quality images on a plurality of print media.

Also, in the above line dot recording apparatus, a line dot recording apparatus capable of continuously feeding and discharging a plurality of print media and uniformly forming the image quality printed on each of the plurality of print media. It is a second problem to provide the above.
Furthermore, in a configuration generally similar to the above line dot recording apparatus, line dot recording that forms an image on a plurality of printing media with good efficiency (temporal throughput) captured by the number of printed sheets per time (for example, per second). It is a third problem to provide an apparatus.

  As a means for solving the above first problem, the present invention has a predetermined outer peripheral length capable of mounting a print medium on the outer periphery, and is driven by a drum driving unit and is in proximity to the outer periphery of the drum. A recording head arranged in a line in the main scanning direction at intervals corresponding to a predetermined pixel density in a predetermined printing area where a recording element to be printed by a plurality of jet nozzle ejection ports is to be printed, and mounted on and held by the rotating drum Position adjusting means for adjusting the position of the recording head in the radial direction of the rotary drum so that the gap between the print medium and the plurality of jet nozzle ejection openings is a gap position suitable for the print medium, The length of the print medium in the sub-scanning direction is set as a reference length, and the drum has an outer peripheral length of N times as an integer equal to or larger than 2 and on which N print media are mounted and held. of The drum is rotated so that the printing medium moves in the sub-scanning direction with respect to the recording head at a double speed higher than the reference speed at which the dot recording on each pixel of the printing medium has a predetermined pixel density in the operation cycle of the recording head. This is a line dot recording apparatus configured to record dots on each pixel by N-pass printing with N rotations to form an image on a printing medium.

  According to the line dot recording apparatus of the present invention configured as described above, the throughput is reduced in a multi-pass method (printing time per printing medium) for a predetermined printing area of a plurality of printing media mounted on the rotating drum. Image quality can be efficiently formed without causing a long period of time. However, when the rotating drum is rotated at the reference speed as in the past without rotating the rotating drum at a reference speed or higher and dots are recorded so that the recording head has a predetermined pixel density, each pixel in the sub-scanning direction is recorded. Since dots are recorded successively and sequentially adjacent to each other, if this dot recording operation is performed by N-pass printing, dots are recorded every N pixel intervals, but dot recording is completed on all pixels of N sheets. Requires N times as much time and throughput decreases.

  Therefore, if the N-pass printing operation is performed and the drum rotation speed (circumferential speed) is set to a double speed higher than the reference speed, a decrease in throughput is prevented. For example, when this double speed is set to N times the reference speed, the drum recording time for each pixel at every N pixel interval is 1 / N times, that is, the original recording speed is returned to N sheets of the printing medium. The speed reduction due to the increase in speed, that is, the reduction in throughput, is eliminated, and the recording operation can be performed with the highest efficiency while operating the head at the maximum operating frequency. Since dots are recorded on one printing medium by N-pass printing, the first and Nth pixels are dot-recorded on each printing medium every rotation, and N sheets are printed at N rotation. Dots are recorded for all the pixels.

  The variable N is N sheets of print media, N rotations of the drum, and N pass of printing is an integer of 2 or more. However, the speed above the reference speed of the drum is not only N times but above the reference speed (1 or more). It is sufficient that the improvement in throughput is at least fast enough to be effectively recognized as compared with the conventional reference speed. That is, not only N times the integer but also a real number m times larger than the reference speed, such as 1.5 times or 3.8 times.

  The recording head is supported by a support means, and the position of the recording head can be adjusted in the radial direction of the rotary drum by a member that adjusts the position so as to hold the optimum gap with respect to the printing medium according to the thickness of the printing medium. It is supported by the position adjusting means. In this case, the optimum gap means that various errors such as a difference in the thickness of the printing medium, the roundness of the circumferential surface of the rotating drum occur, and the mechanism for holding the printing medium is further than the outer circumference of the printing medium. The gap is suitable for supporting the plurality of inkjet nozzle outlets closest to the print medium in accordance with the size of the rotating drum and ink landing points so that dot recording can be performed without any trouble even when a business trip is made. In this way, by setting an optimal gap, a uniform (uniform) pixel (image) can be formed for each print medium.

Further, the line dot recording apparatus may be an apparatus having the following configuration instead of the recording apparatus. That is, a rotary drum having a predetermined outer peripheral length on which the print medium can be mounted on the outer periphery and driven to rotate by the drum driving means, and a recording element by a plurality of jet nozzle discharge ports are printed in the vicinity of the outer periphery of the drum. And a recording head arranged in a line in the main scanning direction at intervals corresponding to a predetermined pixel density in a predetermined printing area, and the rotating drum has a length in the sub-scanning direction of the print medium as a reference length. The drum is a drum on which N print media are mounted and held, and the dot recording on each pixel of the reference length print medium is performed by the recording head. The drum is rotated so that the printing medium moves in the sub-scanning direction with respect to the recording head at a real multiple speed that is equal to or higher than a reference speed that provides a predetermined pixel density in the operation cycle. Pixel It can be Tsu preparative recorded and constructed by a line dot recording apparatus to form an image on a print medium.
The operation of such a line dot recording apparatus is basically the same as that of the first invention except for the function of the position adjusting means.

  In the dot recording apparatus having the above configuration, in order to form a more uniform and clear image on each pixel of N sheets, head moving means for moving the recording head in the main scanning direction and the return direction with respect to the rotating drum is provided. It is preferable to connect to a recording head and perform dot recording on each pixel. This is because each nozzle has subtle variations in shape and size, and the recording head is moved to make this uniform. However, the movement distance, movement, reversal time, acceleration, and deceleration of the recording head are set to the extent necessary for multi-pass printing of N sheets, N rotations, double speeds higher than the reference speed, and N-pass. It is not as big as the method.

  By applying the N-pass multi-pass printing method using the rotating drum as described above, N printing media are mounted on the outer peripheral surface of the drum, and the printing is performed on the N printing media at a double speed higher than the reference speed and N rotations. In order to continuously perform the dot recording in the apparatus, it is necessary to include a printing medium feeding means, a drum mounting / holding means, and a paper discharging means (second problem described above). As means adapted to this, a paper feeding means for feeding the rotary drum at a predetermined paper feed position at a predetermined number of rotations of the rotary drum, a means for mounting / holding N print media on the rotary drum, and a mounting The rotary drum is provided with a paper discharge means for removing the discharged print medium at a predetermined discharge position for each predetermined number of rotations of the rotary drum, and discharging the plurality of print media to the rotary drum sequentially at a predetermined timing. A configuration in which images of the same quality are continuously formed on a plurality of print media by feeding, mounting / holding, and discharging can be employed.

  With such a configuration, a plurality of print media can be continuously fed to the drum at predetermined timings (at regular intervals), and an image of the same quality can be formed on each print medium. In this case, the nozzles of different recording elements may be operated for a plurality of print media, and the print images may be dot-recorded on the plurality of media in the same order to form an image, or printing may be performed. The images may be formed in the order of different print images using the same nozzle with respect to the print image of the medium. In either case, the obtained image has a uniform image quality on all of the plurality of print media.

  As means for solving the third problem, a rotating drum having a predetermined outer peripheral length capable of mounting a print medium on the outer periphery and driven to rotate by the drum driving means, and a plurality of jet nozzles in the vicinity of the outer periphery of the drum And a recording head arranged in a line in the main scanning direction at intervals corresponding to a predetermined pixel density in a predetermined printing area where the recording element by the discharge port is to be printed. This is the reference length, and the outer peripheral length is N times or more, which is an integer of 2 or more, and is a drum on which N print media are loaded and held. In this way, dots are recorded on each pixel to form an image on the printing medium, and a sheet feeding unit that feeds the rotating drum at a predetermined sheet feeding position, and N printing media are mounted and held on the rotating drum. Means and fitted The rotating drum is provided with a discharging unit that removes the printed medium at a predetermined discharging position and discharges the printed medium, and feeds and discharges the sheet by the feeding unit every (1 + 1 / N) rotation of the drum with respect to the rotating drum. It is preferable that the line dot recording apparatus is configured to perform paper discharge by paper means.

  In the line dot recording apparatus having such a configuration, the paper is fed and discharged by the paper supply means and the paper discharge means once for each (1 + 1 / N) rotation of the drum.

  The efficiency (temporal throughput) grasped by the number of printed sheets per time (for example, per second) by performing dot feeding by performing such paper feeding and paper discharge on the drum at the above-mentioned fixed time intervals is not necessarily plural. Even if a single print medium is mounted on the drum, the print quality is not lowered, and the print quality is improved without lowering the time efficiency at the drum rotation speed.

  As described above in detail, the line dot recording apparatus according to the present invention has a plurality of recording elements arranged in a line in the main scanning direction at intervals corresponding to a predetermined pixel density in the vicinity of a rotating drum capable of mounting N sheets. And a rotating drum capable of dot recording on each pixel at a predetermined pixel density at a speed equal to or higher than a reference speed, and an image is formed by N rotation in an N-pass multi-pass method. In addition, it is possible to eliminate the decrease in throughput when forming an image by multi-pass recording and to efficiently form a high-quality image on a sheet.

  Further, a head moving means for moving the recording head in the main scanning direction and the return direction is connected to the recording head with respect to the apparatus having the above configuration, and a sheet feeding means for feeding the rotating drum at a predetermined number of revolutions, and N sheets A sheet loading / holding unit and a sheet discharging unit that discharges paper at a predetermined number of rotations are provided, so that continuous printing can be performed at high speed while uniformly maintaining the print quality of each sheet by continuously supplying the sheet. This makes it possible to obtain a remarkable effect that a large amount of printed matter can be efficiently printed by a jet nozzle type dot recording apparatus.

  In the above-described continuous supply type line dot recording apparatus, the recording head is moved to N positions, and dots are recorded by the recording elements in the same print image order in each pixel, thereby printing images on N sheets in the same order. By performing dot recording and making the overlapping of the printing colors for each paper the same, and making the printing colors the same, it is possible to obtain an effect that the printing quality for each paper can be ensured uniformly. Alternatively, when the recording head is moved to N positions and the same nozzle is used for printing for each sheet, the color tone and the dot position change due to the difference in nozzle are eliminated, and the printing color is the same. By doing so, it is possible to obtain an effect that the print quality for each sheet can be ensured uniformly.

  Further, in the line dot recording apparatus in which sheet feeding by the sheet feeding unit and sheet ejection by the sheet discharging unit are performed for each (1 + 1 / N) rotation of the drum, the time efficiency is lowered. The machine structure can be simplified by improving the print quality by continuous paper feeding at predetermined intervals without repeating a series of operations from paper feeding to paper discharge at the same intervals. An effect is obtained.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram illustrating a schematic configuration of a line dot recording apparatus according to an embodiment. As shown in the figure, the line dot recording apparatus A includes a nozzle head 1 having a large number of ink jet type ejection ports (nozzles), and a rotary drum 2 provided so as to be rotatable in the vicinity of the nozzle head 1. .

  The rotary drum 2 is provided with a paper feed means 3 comprising a paper feed roller 3c and the like for feeding a sheet of printing medium sent from the conveyor 3a to the rotary drum 2 via a swing gripper 3b. The leading edge of the supplied paper is attached to the drum circumferential surface with a claw 4a, and a mounting / holding means 4 is provided by a clamp 4b for holding the middle of the paper, and a discharge roller 5a and a chain 5b are provided on the discharge side. Further, a paper discharge means 5 comprising a gripper claw 5c and the like is provided. Reference numeral 6 denotes a suction feed unit, and 7 denotes a paper storage case.

In FIG. 1, only one nozzle head 1 is shown for simplification of the drawing, but actually, a total of 10 sets of nozzle heads 1 are arranged along the substantially upper half circumference of the drum 2 as shown in FIG. (1 _Y , 1 _M , 1 _C , 1 _B ) are provided, and each of the three colors 1 _Y , 1 _M , 1 _C is made up of two nozzle heads, each one color unit, for black In order to ensure a reliable black color, four nozzle heads are separately provided to make the color black. In the illustrated example, the rotating drum 2 has an outer peripheral length capable of mounting at least four sheets of standard size A ₃ , and mounting / holding means for mounting and holding each of the four sheets on the drum peripheral surface. Four sets of 4 are also provided. The rotary drum 2 is rotationally driven at a predetermined rotational speed and a constant speed by a drive motor (not shown). The rotation speed will be described in more detail later.

FIG. 3 is a diagram showing a lower bottom surface on the drum outer peripheral surface side of the nozzle head 1, and FIG. 4 is a cross-sectional view seen from an arrow IV-IV in FIG. As shown, the nozzle head 1, under the bottom plate 1 _FB U-shaped cross section of the support frame 1 _F shown in cross section in FIG. 4, (7 pairs in the illustrated example) a plurality of which two nozzle units back to back The nozzle unit pairs 1 _Y1 to 1 _Y7 are provided in a staggered manner and arranged in the main scanning direction which is the paper width direction (drum width direction), and has a moving means 10 for moving the entire nozzle head 1 to the left and right. .

The subscript Y indicates the 1 _Y head of the nozzle head 1, and the subscripts are M, C, and B for 1 _M , 1 _C , and 1 _B , respectively. The “main scanning direction” simply means the width direction of the paper, and ink is simultaneously ejected from every other (thinned out) nozzle ejection port in the main scanning direction (a plurality of nozzle ejection ports in the main scanning direction are The ink is not ejected by scanning with a slight delay in ejection timing). However, in the illustrated example, every other nozzle outlet is ejected, but the number of thinning out nozzles can be two or more, or irregular thinning such as one and two, two and three. Also, the discharge can be performed without thinning.

Nozzle head 1 _Y, 1 _M, 1 _C, as shown in FIG. 2, has two heads a pair, for example 1 _Y, 1 nozzle unit provided in the 1-way head 1 _Y of the _Y 1 _Y1 The two units have a nozzle discharge port with a resolution of 150 dpi per unit, so that the nozzle unit 1 _Y1 has 300 dpi and the two heads 1 _Y and 1 _{Y have} a resolution (pixel density) of 600 dpi. It will have a discharge port. The nozzle discharge ports of this resolution are all provided in the same manner for the other nozzle units 1 _Y2 to 1 _Y7 .

The resolution (pixel density) of 600 dpi by both of the two heads 1 _Y and 1 _Y is such that when two nozzle units 1 _Y1 are combined back to back in one head 1 _Y , the pitch between two adjacent dots is 150 dpi. When the recording elements of the respective ejection ports (nozzles) are provided at a gap (about 0.17 mm) with a half-pitch shift to 300 dpi, the two heads 1 _Y and 1 _Y are combined. It is set by combining so that the pitch between the recording elements is located at ¼ pitch (about 40 μm).

The reference period (frequency) of each nozzle unit 1 _Y1 (maximum dot recording speed by nozzle discharge) is 9.6 kHz in the illustrated example, and the rotating drum 2 has a rotating speed of 11.25 rpm (drum peripheral speed 24 m / min, drum When rotating at a diameter D = 70 cm), the speed at which the nozzle dot diameter of 40 μm is arranged adjacent to each other in the sub-scanning direction is used as a reference speed, and the drum is driven to rotate at a rotational speed (45 rpm) four times the reference speed. Dots are recorded so as to have a resolution. However, the quadruple speed of the reference speed is shown as an example, and the speed is not necessarily limited to the quadruple speed. It is not less than the reference speed (one or more real number m times), and at least the improvement of the throughput is the conventional reference speed. It is sufficient that it is as fast as it can be effectively recognized as compared with the case of. That is, not only N times the integer but also a real number m times larger than the reference speed, such as 1.5 times or 3.8 times.

Accordingly, the drum rotation speed (peripheral speed) may be equal to or higher than the reference speed, but particularly when it is described as an integer multiple value such as a quadruple speed, for example, it can be regarded effectively as a quadruple speed such as 3.8 times. The range is referred to as quadruple speed for convenience. The same applies to the case of integer multiple speeds of 2, 3, 5, 6, 7,. However, in the following description, a specific example will be described focusing on the case of quadruple speed for easy understanding. The nozzle unit 1 _Y1 and 1 _Y7 at both ends is provided to match the maximum width of paper to be used (e.g., long side lengths of A ₃ paper), the feed of the image signals for the smaller sheets which The nozzle discharge port corresponding to the necessary width is operated by limiting.

The head moving means 10 is independently connected to the nozzle head 1 so as to move each head of the nozzle head 1 (1 _Y , 1 _M , 1 _C , 1 _B ) in the main scanning direction. a stepping motor 10m fixed to, attachment through the output shaft, and penetrated the screw shaft 10s coupled to the output shaft to the support frame 1 _F through a ball screw joint 10 _T, when rotating the stepping motor 10m The support frame 1 _F is configured to be movable in the main scanning direction (and the opposite direction). Note that become possible on the other of the fixed frame 11 detects the end surface of the support frame 1 _F, detects the position of the origin of the movement of the carriage (moving means 10). 10 _G is a guide rod for guiding and supporting the nozzle head 1 supported by the support frame 1 _F in the axial direction.

  As will be described later, the head moving means 10 is moved and stopped from a predetermined position at a plurality of positions (N) with respect to the paper, and the acceleration / deceleration at the time of stopping the movement is 0. The movement distance is about 1 G, and the maximum movement distance at one time is about 20 mm, and the whole is about 30 mm. The operation time in one direction is about 0.3 seconds, and the time from the stop to the start of the next operation is about 1.3 seconds.

  The paper feed means 3 feeds the end of the paper sent from the conveyor 3a to the paper feed roller 3c with a swing gripper 3b, and further holds the end of the paper at a predetermined timing with a gripping claw provided on the paper feed roller 3c. When the rotary drum 2 rotates with the gripping claw 4a of the drum 2 and the gripper 4a of the drum 2 is rotated, the paper is fed by being lightly pressed by the clamp 4b so that the paper does not float from the outer periphery of the drum. The clamp 4b clamps the paper by lightly pressing it with a pressing member of the clamp 4b provided on the outer peripheral surface of the drum (provided in the drum width direction, but not shown for simplification). Yes.

  The suction feed unit 6 provided in front of the conveyor 3a of the paper feeding means 3 rotates after sucking the leading edge of the paper by the suction arm 6b from the storage case 6a for storing paper and raising the suction arm 6b by a predetermined stroke. The suction arm 6b can be moved up and down and can rotate about the shaft 6x so as to deliver the paper onto the conveyor 3a. Further, a plurality of suction arms 6b are installed in the width direction of the paper, and the plurality of suction arms 6b can be moved up and down all at once and rotated. The sheet fed onto the conveyor 3a is aligned with the position in the width direction and the position in the longitudinal direction with respect to the front end portion by the registering means 3d provided near the downstream end of the conveyor 3a, and is sent to the swing gripper 3b at a predetermined timing. Sent out.

  The paper discharge means 5 is formed by attaching a gripping claw 5c to an endless chain 5b. When the end of the paper comes to a predetermined position before the paper discharge roller 5a, the gripping claw 5c is moved at a necessary timing. The gripper claw 4a on the drum side is pressed to peel off the end of the paper from the drum, the end of the paper is gripped by the gripper claw 5c, and the sheet is fed downward by the paper discharge roller 5a. The storage provided below the two rollers. The case 7 is stored.

Further, reference numeral 12 in FIG. 2 denotes a fulcrum shaft, which is a shaft that rotatably supports the wing frame 13 having a curved shape along the peripheral surface of the drum for mounting the 10 sets of nozzle heads 1 described above. The wing frame 13 is divided into two parts on the left and right at a position directly above the drum 2 and is configured such that both ends jump up with the fulcrum shaft 12 as a fulcrum. The support frame 1 _F of each nozzle head 1 described above is fixed to both ends of the wing frame. Therefore, the support shaft 12 and the wing frame 13 form a support means T for the nozzle head 1.

The nozzle head 1 serving as the recording head is attached to the wing frame 13 so that the position of the nozzle can be adjusted in the radial direction of the rotary drum 2 so as to maintain an optimum gap according to the thickness of the printing medium by the position adjusting means T. It has been. As a specific example of the position adjusting means, an example is shown in FIGS. 12A to 12C. 12A is a view of the position adjusting means T viewed from the outside of the wing frame 13 (however, only a part of the right wing frame 13 and the left wing frame 13 is shown), and FIG. 12B is a view showing each nozzle head 1 (for example, 1 _Y ) is a partial cross-sectional side view taken at the position of the guide rod 10 _G of. As shown in FIG. 12A, the position adjusting means T screws the bevel gear 14b at the shaft end of the adjusting knob (handle) 14a into the gear shaft 14c, and the gear shaft 14c extends along the length of the curved right wing frame 13. one side of the whole nozzle head 1 (1 _Y, 1 _M, 1 _C) to over to partially connecting rod, universal joint, the screw shaft 15a, via a gear 15b or the like rotates in the adjustment shaft 15x each nozzle head 1 is transmitted Are connected to each other. However, manual adjustment using the adjustment knob (handle) 14a may be an automatic adjustment method using a motor.

Further, as shown in FIG. 12B, the position adjusting means T is attached to the lower end of the fixed frame 11 are provided outside the two support frames 1 _F. A suspension member 11b is extended below a leg portion 11a provided at the lower end of the fixed frame 11. As shown in FIG. 12C, the suspension member 11b has an eccentric cam (an eccentric member) at the end of the adjustment shaft 15x. ) 15 is fitted. When the rotation is transmitted to the adjustment shaft 15x through the screw shaft 15a and the gear 15b, the suspension member 11b moves in the vertical direction (vertical direction in FIG. 12B) with respect to the wing frame 13 by the eccentric phase position of the eccentric cam 15. The position shifts.

In this case, as shown in FIGS. 12B and 12C, a pair of guide holes having different diameters are formed in the suspension member 11 b, and project from the wing frame 13 corresponding to each nozzle head 1. A pair of guide rods 11d are erected in parallel to each other on the provided support plate 11c, the pair of guide rods 11d are inserted into the pair of guide holes, and a coil spring of an elastic member is placed on the large diameter side of the guide holes. 11e is inserted. The elastic member is always inserted in a compressed manner so as to push up the space between the suspension members 11b relative to the support plate 11c, and the position of the suspension member 11b relative to the support plate 11c, that is, the wing frame 13 can be adjusted by the phase position of the eccentric cam 15. It is configured. Accordingly, the position of the nozzle head 1 between the frames 1 _F and 1 _F supported by the guide rods 10 _G and 10 _G through which the fixing plate 11 provided on the suspension member 11 b is inserted is also adjustable. It will be.

  Ideally, the optimum gap is as small as possible. In practice, however, the thickness of the paper, the roundness or eccentricity of the rotating drum 2, errors on the surface of the rotating drum of the printing medium, etc. Considering various errors such as unevenness of adhesion at each circumferential position, the gap can not be zero, and even if each error occurs, dot recording can be performed without trouble, and multiple ink jet nozzle outlets can be formed on the paper This is the gap that is most suitable for the closest placement and is an empirically determined amount. In the example shown in the figure, for example, it is set to about 0.9 mm, and the approach and separation can be adjusted very slightly according to the thickness of the sheet with the gap size as the center.

  Further, the grip claw 4 a and the clamp 4 b of the drum 2 described above are provided as close contact means M for closely contacting the sheet to the peripheral surface of the drum 2. When the sheet floats even slightly from the drum peripheral surface, the gap with the inkjet nozzle discharge port varies depending on the position of the sheet, and a uniform (uniform) image cannot be printed for each sheet. It is also an important means for optimally maintaining the gap with the discharge port. As another example of the close contact means M, the inside of the drum may be lowered by a suction pump, and a plurality of small holes may be provided on the drum peripheral surface to suck and close the paper. In that case, it is preferable to divide the inside into the same number corresponding to at least four sheets (N sheets) so that suction can be brought into contact with each section.

In the line dot recording apparatus A of the embodiment configured as described above, dot recording (printing) is performed as follows. In order to avoid complicating the description, a single nozzle head 1 will be described as a representative as shown in FIG. 1 (the so-called nozzle unit may be described as a nozzle head for convenience. ). In the actual apparatus A, color printing is performed by linking the following operation of one nozzle head 1 with two sets and / or four sets for each color as a whole. In FIG. 5A, for example, the nozzle head 1 _Y7 is assumed to be representative. As shown in the figure, each nozzle head 1 _Y7 has an interval of each pixel corresponding to the pixel density required for the paper corresponding to a plurality of ink ejection ports (nozzles) No. 1 to 14 in the main scanning direction. Are provided at the same pitch.

In FIG. 5B, numbers 1 to 14 in the main scanning direction indicate dot recording positions on the paper, and numbers 1 to 9 in the sub scanning direction indicate dot recording positions in the sub scanning direction on the paper. One of the squares represents one dot. Accordingly, in this case, it is assumed that the area to be dot-recorded by one nozzle head 1 _Y7 extends rightward at addresses No. 1 to 14 to in the main scanning direction in FIG. By rotating, the sheet is fed in the direction opposite to the sub-scanning direction in the figure, and dot recording is also performed in the sub-scanning direction.

At the start of dot recording, it is assumed that the nozzle No. of the nozzle head 1 _Y7 coincides with the address No. in the main scanning direction shown in FIG. In addition, (b) the numerical symbols in the figure represent the nozzle number for recording the dot and the dot recording order. For example, 1-1 indicates that dot recording was performed at the position indicated by the first dot recording of the No. 1 nozzle, and 1-2 indicates the second dot recording of the No. 1 nozzle. (Not shown) 2-1 indicates the first dot recording of the No. 2 nozzle, 2-2 indicates that the second dot recording (not shown) of the No. 2 nozzle is performed, respectively. .

At the start of dot recording, the nozzle head 1 _Y7 is placed at the position of the uppermost carriage position No. 1 in (a), and No. 1, 3, 5, ₇ ,. ... (Odd number of rows) of nozzle ejection ports are ejected all at once, and dots No. 1-1, 3-1, 5-1,. Then, when the nozzle head 1 _Y7 advances relatively in the sub-scanning direction due to the rotation of the drum 2 and the nozzle head 1 _Y7 is positioned at the address No. 5 in the sub-scanning direction, the odd number No. Ink is ejected from the nozzle ejection openings of FIG.

Further, the same dot recording in the main scanning direction is performed one after another at each address position No. 9, 13, 17,... In the sub scanning direction, and multipass dot recording is performed every four dots in the sub scanning direction. . When such multi-pass dot recording of the first rotation is performed on the entire printing area in the sub-scanning direction of one sheet, the nozzle head 1 _Y7 is moved until the next multi-pass dot recording of the second rotation is started. (A) As shown in the figure, it is placed at a carriage position No. 3 which is moved by 6 dots in the example shown in the direction opposite to the main scanning direction.

The carriage position No. is set to No. 1 with the position of the nozzle head 1 _Y7 at the start of recording as a reference position, and is set to 2, 3, and 4 in order from the reference position. Therefore, the carriage No. is 3 because the second multi-pass dot recording moves by 6 dots. At the time of dot recording at the second rotation, as shown in the drawing, even-numbered nozzle discharge ports thinned out one by one in the row in the sub-scanning direction No. 1, that is, nozzle discharge ports No. 8, 10, 12, 14,. ... Dots are recorded on even-numbered No. pixels, that is, No. 2, 4, 6, 8,...

When the nozzle head 1 _Y7 advances relatively in the sub-scanning direction, the odd-numbered nozzle discharge ports thinned out one by one in the No. 3 row, that is, the nozzle discharge ports No. 7, 9, 11, 13, Are dot-recorded on the odd-numbered No. pixels, that is, No. 1, 3, 5, 7,..., And the nozzle head 1 _Y7 is installed in the sub-scanning direction. As the process proceeds, dot recording is performed in the same manner in each of No. 7, 11,. Thereafter, before the dot recording of the third rotation is started, the nozzle head 1 _Y7 further moves 3 dots in the direction opposite to the main scanning direction, and is placed at the position of the carriage position No. 4.

When the first sheet enters the third rotation, the even nozzle discharge ports in the row in the sub-scanning direction No. 2, that is, the nozzle discharge ports No. 10, 12, 14, 16,. No. 1, 3, 5, 7,..., Dots are recorded. Then, when the nozzle head 1 _Y7 advances in the sub-scanning direction, No. 2 at each nozzle of the odd-numbered nozzle discharge ports, that is, nozzle discharge ports No. 11, 13, 15,. Dot recording is performed on each of the pixels 4, 6, 8,. Further, when the nozzle head 1 _Y7 advances in the sub-scanning direction, each nozzle of the even-numbered nozzle discharge port in the No. 6 row, each nozzle of the odd-numbered nozzle discharge port in the No. 8 row, and so on. For each even-numbered row, even-numbered and odd-numbered nozzle discharge ports are dot-recorded alternately every other dot.

Thereafter, before shifting to dot recording at the fourth rotation of the drum, the nozzle head 1 _Y7 is returned to the main scanning direction, moved 6 dots, and placed at the carriage position No.2. In the fourth rotation of the drum, the nozzles of the odd-numbered nozzle discharge ports in the row in the sub-scanning direction No. 2, that is, the nozzles of the nozzle discharge ports No. 5, 7, 9, 11,. .., That is, dots of (5-4), (7-4), (9-4),... Are recorded.

Then, when the nozzle head 1 _Y7 advances in the sub-scanning direction, No. 4 at the nozzles of even-numbered nozzles, that is, nozzles of nozzles No. 4, 6, 8, 10,. .., That is, dots (4-4), (6-4), (8-4),... Are odd-numbered in the No. 6 row. Nozzle outlets, that is, nozzle outlets No. 5, 7, 9, 11,..., Each pixel No. 2, 4, 6, 8,. , (7-4), (9-4),...

As described above, when the nozzle head 1 _Y7 is moved to N positions (N = 4) including the reference position in the main scanning direction and the return direction, within the maximum moving distance in the main scanning direction (in the illustrated example, 9 dots), and moves to and stops between adjacent positions (for example, carriage positions No. 1 and No. 2 and No. 2 and No. 3) at equal positions (3 dots in the example shown). The head moving means is connected to the nozzle head so as to be movable by a distance (print images 1, 2, 3, 4) that can form a plurality of predetermined print images. However, it is an example for explanation that the equal distance between adjacent positions is 3 dots, and this distance is arbitrarily set. For example, if the number of nozzle discharge ports of the nozzle head is increased, the number Depending on, a large distance such as 5, 10, 10,... Dots is set.

The nozzle head 1 _Y7 moves from the position of the carriage position No. 1 as the reference position in the direction opposite to the main scanning direction, and the nozzle discharge port located outside the predetermined dot recording area, for example, the carriage position No. 3 Nozzle outlets No. 1 to No. 6 stop the ink discharge operation during the second dot recording. The same applies to the nozzle discharge ports No. 1 to 9 at the carriage position No. 4 and the nozzle discharge ports No. 1 to 3 at the carriage position No. 2. The above operation is repeated with the nozzle heads 1 _Y7 to 1 _Y1 and with the two nozzle head units to perform dot recording for one color in the required recording area of one sheet of paper, and the same operation is performed for the other colors. Is repeated to perform color printing.

  As described above, when the carriage position No. moves from 1 → 3 → 4 → 2, the acceleration / deceleration is about 0.1 G, the maximum movement distance is about 30 mm, and the one-way operation time is about 0.3 seconds. Although the time from the start to the start of operation is about 1.3 seconds, such a movement and stop mode is achieved by a conventional serial printer (see, for example, Patent Document 3) in which the carriage quickly and rapidly adjusts the entire width of the paper. This is because, in this example, the line head printer type is basically adopted and the recording head is configured to move and stop at an extremely small distance, acceleration / deceleration, and short operation time. .

  Moreover, the moving distance, acceleration / deceleration, and operation time settings described above are in the form of a rotating drum and correspond to the printing operation on four sheets of paper, dot recording at four rotations, four times speed, and four passes. is there. Therefore, when setting the above moving distance, acceleration / deceleration, operation time, etc. for N sheets other than N = 4, N rotation, double speed over reference speed, N pass, respectively, it is optimal according to the value of N Set to

  The above is the action of dot recording on the first sheet based on FIG. 5, and FIG. 5 shows the result of dot recording for four rotations overlaid on all the pixels. FIG. 6 shows the relationship between the nozzle number used for dot recording on each pixel and each pixel for each rotation. However, in this figure, the first rotation ○ 1 is (1-1), ○ 2 is (2-1), ○ 3 is (3-1), ○ 4 is (4-1),. Δ7 in the second rotation represents (7-2), Δ8 represents (8-2), Δ9 represents (9-2), and Δ10 represents (10-2). 10 is (10-3), ▽ 11 is (11-3), ▽ 12 is (12-3), ▽ 13 is (13-3), □ 4 of the fourth rotation is (4-4), □ 5 represents (5-4), □ 6 represents (6-4), and □ 7 represents (7-4).

In FIG. 6, C ₁ , C ₃ , C ₄ and C ₂ indicate carriage position codes. In the first sheet, the carriage changes in the order of C ₁ → C ₃ → C ₄ → C ₂ as described above. You can see that FIG. 6 shows that dot recording is performed on the second sheet in the same image order as the first sheet. In this case, nozzles with different numbers are used as nozzles corresponding to the same pixel position. For example, the print image number 1 of the first rotation of the first sheet has nozzles No. 1, 3,... On the first line, and nozzles No. 2, 4,. In print image number 2, nozzles No. 8, 10... Are operated in the first line, and nozzles No. 7, 9,. Has been.

  On the other hand, the printing image number 1 of the first rotation of the second sheet is such that the nozzles No. 7, 9... In the print image number 2, the nozzles No. 11, 13... Are operated in the first line, and the nozzles No. 10, 12,. Is formed. Therefore, it can be seen that the first print image number and the second sheet print image number of the first rotation are exactly the same (print image number 1), and the nozzles are nozzles of different numbers. The same applies to the third and fourth sheets.

However, carriage position of the first rotation in the second sheet is C _3, the second rotation C ₁ and changes in C _2, 4 revolution in C _4, 3 th rotation, the third sheet C ₄ → C ₂ → The carriage position at the start of printing changes every second rotation of the first sheet, such as C ₁ → C ₃ , C ₂ → C ₁ → C ₃ → C _{4 in} the _fourth sheet. It turns out that it changes in a cycle starting from one by one in the same order. The above description is based on a representative nozzle head for one color. Actually, the nozzle heads for each color perform the same operation with a slight shift in timing. The color overlap is also the same, and the printing color of each paper can be made the same.

In the above embodiment, the head moving means 10 causes the nozzle head 1 (1 _Y , 1 _M , 1 _C , 1 _B ) to move in the main scanning direction by a predetermined short distance range as shown in FIG. has been described on the assumption that reciprocate within a 1 each nozzle head without providing _Y head moving means 10, 1 _M, 1 _C, 1 in the example of the plurality of sets of nozzle heads each (shown in _B 4 pairs Thus, the same dot recording action as described above can be obtained. However, in this case, as shown in FIG. 5A, the plurality of sets of nozzle heads are not fixed at the moved positions, but the plurality of sets of nozzle heads are all at the same reference position as the carriage position No. 1. The positions are adjacent and fixed in the sub-scanning direction. Accordingly, in the example shown and described in FIG. 5, it is possible to obtain the same recording action by operating different jet nozzle discharge ports of a plurality of nozzle heads so as to have the same recording action as the dot recording shown in FIG. it can.

  The above-described printing on the four sheets is a case where the maximum number of sheets that can be mounted on the drum is preliminarily mounted and dot recording is performed with four rotations by a four-pass multi-pass method, and until all four sheets are printed. It is assumed that the sheet is held on the rotary drum 2 and thereafter the same printing is repeated by replacing four sheets. However, since the printing of the first sheet is actually finished before the fourth rotation of printing on the second and subsequent sheets starts, the first sheet is printed when printing is performed efficiently in large quantities. After discharging, if the next sheet is supplied to that position, continuous printing can be performed. Therefore, a case where a large amount of printing is performed in which paper is continuously supplied at regular time intervals and printing is continuously performed will be described below.

  In the rotating drum 2, four gripping claws 4a allow four sheets to be mounted on the drum at equal intervals (however, four sheets are not always mounted at the same time). As shown, No. 1 gripping claw at the paper feeding position where the paper is fed from the right paper feeding means 3, and No. 2, No. 3, in the rearward direction of the drum rotation direction (counterclockwise), No. 4 four grip claws are provided, and the paper is discharged by the paper discharge means 5 when the paper comes between the positions No. 3 and No. 2. FIG. 8 is a diagram for explaining the sheet feeding sequence with respect to the drum rotation position (phase). It changes in the order of (a) → (i) in the figure, and four sheets are sequentially mounted on the four claws No.1 to No.4.

  However, since description will be complicated if all the actual nozzle heads 1 shown in FIG. 2 are described, a schematic diagram in which one nozzle head 1 is representatively placed above the drum on the drum center line in FIG. As shown. Therefore, in the following description, FIGS. 9A and 9B will also explain the relationship between the supply of each sheet, the printing order, and the paper discharge in correspondence with this schematic diagram.

  9A and 9B are pseudo time chart diagrams showing fluctuation states in which the paper feed timing, printing, and paper discharge state at each nail No. change using the base pulse BP as a reference timing signal. The base pulse BP is expressed as one pulse every 1/4 rotation of the drum, and the base pulse 1 is set when the nail of No. 1 is in the horizontal position on the right side of the drum, and thereafter the drum rotates 1/4. Increment by one each time.

  FIG. 8A shows a sheet feeding start state, and when the first sheet is fed from the sheet feeding means 3 at a predetermined timing, it is held by the claw No. 1 and is mounted on the drum peripheral surface to be drums. Sent with 2 rotations. When the base pulse BP becomes 2, the first sheet starts to pass under the nozzle head 1 and printing is started, and dot recording is performed on a predetermined area of the first sheet by the dot recording method described above. When the first rotation of printing on the first sheet is completed and the base pulse BP becomes 3, since the second sheet is not yet loaded on the drum 2, the carriage is moved at that position. .

  This is because the carriage position is moved to No. 3 in the second dot recording on the first sheet described above, and the carriage of the nozzle head 1 at a timing when there is no sheet under the nozzle head 1. This is because the position needs to be moved. FIG. 8B shows the state of the drum when the nozzle head 1 starts to move to the carriage position No. 3. Further, when the drum 2 continues to rotate and rotates once by the base pulse 4, and then further rotates by 1/4 by the base pulse 5, as shown in FIG. At the same time, the second sheet is supplied from the sheet feeding means 3, and the nail No. 2 clamps the leading edge of the sheet.

  The drum 2 is further rotated 1/4 by the base pulse 6, and the second dot recording described above is performed on the first sheet during the transition from FIG. 8 (c) to FIG. 8 (d). When the dot recording is completed, the second sheet of paper added by the nail No. 2 reaches immediately before the nozzle head 1. Therefore, while the drum 2 is further rotated 1/4 by the base pulse 7, dot recording of the first rotation is performed on the second sheet on the second sheet (e). move on.

  When the drum 2 further rotates 1/4 of the state shown in FIG. 8E with the base pulse 8, the third sheet is not yet loaded on the claw No. 3, so that the carriage is moved during this timing. The carriage No. shifts from 3 to 4. With this 1/4 rotation, the drum starts the third rotation through the reference position of the first claw No.1. Then, after 1/4 rotation with the base pulse 9, the dot recording of the third rotation is performed on the first sheet while the base pulse 10 further rotates 1/4, and the second sheet is used for this sheet. Begins the second turn.

  FIG. 8F shows a state in which the dot recording of the third rotation on the first sheet is completed with the base pulse 10 and the 1/4 rotation is advanced just before the second rotation of the second sheet starts. As shown in the figure, at this time, the nail No. 3 is supplied with the third sheet from the sheet feeding means 3, and the leading end of the sheet is held by the nail No. 3. Then, the second pulse is recorded on the second sheet by the base pulse 11, and the second recording starts for the third sheet, and the third sheet advances by 1/4 rotation and proceeds to just before the nozzle head 1. Further, while the base pulse 12 is advanced by ¼ rotation, the first rotation dot recording is performed on the third sheet. The state when the dot recording is completed is shown in FIG.

  In the base pulse 13, it is not necessary to record dots on any of the claws No. 1, 2 and 3 during the quarter rotation by this pulse, and the fourth sheet is not yet added to the claws No. 4. At this timing, the nozzle head 1 is moved from the carriage position No. 4 to No. 2. The first sheet starts the fourth rotation by the base pulse 13. In the base pulse 14, the fourth dot recording is performed on the first sheet, and the second sheet enters the third rotation. A third dot recording is performed on the second sheet by the base pulse 15, and the third sheet enters the second rotation.

  Then, the first sheet is discharged by the base pulse 16, the second rotation dot recording is performed on the third sheet, and the fourth sheet is added by the nail No.4. The state at the beginning of the action at the base pulse 16 is shown in FIG. (H), and the state at the end of the action at the base pulse 16 is shown in FIG. It should be noted that at the timing of (i), since the nozzle head 1 is moved after dot recording on the fourth sheet with the next base pulse 16, 5 pulses from the discharged base pulse 16 to the nail No. 1 Paper is not fed until the end (after 1 + 1/4 rotation).

  In the base pulse 17, the first rotation of the fourth sheet is printed, and in the next base pulse 18, the nozzle head 1 is moved, so that the carriage position is set from No. 2 to 1, and the base pulse In 19, after the fourth rotation is printed on the second sheet, the third rotation is printed on the third sheet in the base pulse 20. As described above, the drum outer peripheral position on which the first sheet loaded with the nail No. 1 is returned to the reference position, the sheet is fed again at the next base pulse 21, and the above cycle is repeated.

  Therefore, the relationship between the carriage position with respect to the four sheets performed in the above cycle, the number of times of printing, and the print image is as follows.

C _{1 to} C ₄ indicate the carriage position No., and I _{m1 to} I _m4 indicate symbols of the print image No. The print image is an entire image of a dot recording pattern shown in FIG. 6, for example, which is dot-recorded every rotation of the first sheet, and No. is given for each rotation.

  10A and 10B show different examples of cycles. In this example, the carriage position number for printing and the print image number for printing at that time are the same. In this case, the order of the print images when printing on four sheets differs depending on the sheets, but instead the head nozzles when printing the same print image are the same. FIG. 11 shows the relationship between the image number and the corresponding nozzle for each of the four sheets in this case.

  As can be seen from FIG. 11, for example, at the second rotation of the first sheet, the pixel position (2-1) (intersection of 2 rows and 1 column), and (2-3) the nozzle positions No. 7 and 9 The whole image recorded by dots No. 8 and 10 in (4-2) and (4-4) is the image of image number 3 in FIG. 6, and similarly the pixel position (2-2) at the third rotation. , (2-4), (4-1), and (4-3) correspond to the nozzles No. 11, 13, 10, and 12, respectively, the image of image number 4, the normal position at the fourth rotation (1-2) , (1-4), (3-1), and (3-3) are dot-recorded with the image No. 2 corresponding to the nozzles No. 5, 7, 4, and 6.

  In the second and subsequent sheets, for example, dot recording is performed in a state where the image number 3 of the first sheet is shifted in the first rotation in the second sheet, and thereafter an image image having the same number as the carriage number is recorded. Dot recording is performed such that the carriage number is shifted. From the above, it can be seen that in this example, the same nozzle is used as the head nozzle when printing the same print image.

  From the above, it can be seen that even when the same nozzle is used for one color in printing for each paper, it is possible to ensure uniform print quality, but in this case as well, each timing is shifted slightly for each color in the same cycle. Since the printing is performed for each paper, the change in color density and dot position due to the difference in nozzles can be eliminated by using the same nozzle, and the printing color for each paper is the same, and the printing is performed for each paper. The quality can be made uniform.

In each of the above embodiments, the print medium is mounted on the outer periphery of N (N = 4) drums with the maximum standard size (A ₃ ). However, this print medium may be N sheets of long paper. In this case, N images of the image formed on the maximum standard size paper are formed on each long paper, and then the long paper is cut into N sheets to form the same quality image on each paper. It is also possible to form a long image according to the long paper, and to obtain a long printed material without cutting after the image formation.

  In the above embodiment, an example of four-sheet rotating drum, four-pass multi-pass method, four-rotation, and four-times speed printing is shown. However, the setting number 4 is 2 or more except for the rotation speed setting number 4. Since any number can be applied as long as it is an integer, the set number is generally expressed as N, and N may be any of 2, 3, 4, 5, 6, 7,. However, in practice, the value of N and the diameter of the rotating drum are within the limits that can be actually applied. Further, when N is changed to 2, 3,..., Nozzle discharge in the main scanning direction is, for example, discharged in the thinned-out state in the same manner as in the case of N = 2 or 3 and N = 4. In the case of N = 5, the discharge is performed in every fourth thinning state, and even if the number of N increases thereafter, the same thinning state as in N = 5 may be used. Various other thinning modes can be selected.

  In the above embodiment, the description has been made centering on the case where the set rotational speed of the drum is N = 4. However, the set number of parameters for N sheets, N-pass multi-pass method, and N-rotation image format parameters. As described above, even if N is an integer of 2, 3, 4, 5, 6, 7,..., The set multiple speed is not only the same integer multiple as N, but also a multiple speed (real number multiple speed) higher than the reference speed. ). For example, even if the parameter N = 4, it can be set to a real number speed that is significantly different from 4 such as 1.5 times the reference speed, and such a real number m (m is a real number of 1 or more) times speed. However, it is only necessary to use a double speed that effectively improves the throughput (shortens the time) as compared with the case of rotating at the conventional reference speed.

  Further, in each of the above-described embodiments, the apparatus for rotating the rotating drum 2 at a high speed equal to or higher than the reference speed to print a large amount of printed matter has been described. Embodiment of a dot recording apparatus including a sheet feeding unit 3, a sheet loading / holding unit 4, and a sheet discharging unit 5 for the number N, N multi-pass, dot recording conditions by N rotation, and continuous printing at a constant interval Can be mentioned. However, since the external configuration is the same as that of the previous embodiment, the illustration is omitted.

  In the line dot recording apparatus of this embodiment, since the rotary drum 2 is rotationally driven at a reference speed or lower, the periodic speed, which is the ink discharge timing from the ink jet discharge port of the nozzle head 1, decreases accordingly. Let In this embodiment as well, the nozzle head 1 may be moved by a predetermined short distance by the head moving means 10, or the head moving means 10 may be omitted and a plurality of nozzle heads 1 may be moved to the position of the moving method described above. These units may be fixed, and each nozzle head 1 may be selected and operated to obtain the same operation as the head moving method. The subsequent scheme is similarly applied to the previous embodiment.

  Further, when the paper supply / discharge means 3 and 5 and the mounting / holding means 4 are provided and the paper is supplied and discharged, the supply / discharge timing is set to (1 + 1 / N) as in the previous embodiment. By making it once per rotation, the paper is continuously fed and discharged at regular intervals in harmony with the dot recording timing, allowing smooth feeding without reducing time efficiency (number of prints per second, time throughput) By discharging the paper, the print quality (image quality) can be improved efficiently even at a low speed. In this case, it is possible to improve the landing position accuracy of the ink dots ejected from the ink jet nozzles on the printing medium, and to reduce the amount of satellites in which small droplets are scattered at positions away from the normal landing position. In order to improve print quality, the double speed value can be set to a value of 1 or less.

  The line dot recording apparatus according to the present invention is widely used in a printing machine or the like as a line printer using jet nozzles that continuously feed a plurality of printing sheets onto a drum and perform mass printing.

Schematic diagram of schematic configuration of dot recording apparatus of embodiment Cross-sectional view of the main part of the device Bottom view of 1 nozzle head of the same device Sectional view seen from arrow IV-IV in FIG. The figure explaining the carriage movement position of 1 nozzle head and the dot recording position and order to many pixels of a printing area Explanatory diagram showing the relationship between the print image and carriage number for each rotation on four sheets of paper Schematic showing the relationship between drum and nail No. Explanatory drawing of feeding timing to drum and paper loading status A diagram for explaining the interrelationship between the base pulse reference carriage position, nail No., printing, paper feed, and paper discharge timing (base pulses 1 to 18) A diagram for explaining the interrelationship between the base pulse reference carriage position, nail No., printing, paper feed, and paper discharge timing (base pulses 19 to 36) A diagram for explaining the interrelationship between the base pulse reference carriage position, nail No., printing, paper feed, and paper discharge timing (base pulses 1 to 18) A diagram for explaining the interrelationship between the base pulse reference carriage position, nail No., printing, paper feed, and paper discharge timing (base pulses 19 to 36) Explanatory drawing which shows the relationship between the print image for every rotation, and the other example of a carriage number Schematic side view of nozzle head position adjusting means for adjusting the gap between the nozzle head and the paper in the radial direction of the rotating drum Sectional side view of the position adjusting means viewed at the position of the guide rod 10 _{G in} FIG. 12A Partial cross-sectional view taken along the line CC in FIG. 12B.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Nozzle head 2 Rotating drum 3 Feeding means 3a Conveyor 3b Oscillating gripper 3c Feeding roller 3d Registration means 4 Mounting / holding means 4a Holding claw 4b Clamp 5 Paper discharging means 5a Paper discharging roller 5b Chain 5c Holding claw 6 Suction feed unit 6a Storage case 6b Suction arm 6x Shaft 7 Storage case

Claims (12)

  A rotary drum having a predetermined outer peripheral length capable of mounting a print medium on the outer periphery and driven to rotate by drum driving means, and a predetermined recording element to be printed by a plurality of jet nozzle outlets in the vicinity of the outer periphery of the drum The gap between the recording head arranged in a line in the main scanning direction at intervals corresponding to a predetermined pixel density in the printing area, and the printing medium mounted and held on the rotating drum and the plurality of jet nozzle discharge ports is the printing medium Position adjusting means for adjusting the position of the recording head in the radial direction of the rotary drum so that the gap position is suitable for the rotary drum, and the rotary drum uses the length of the print medium in the sub-scanning direction as a reference length. A drum having an outer peripheral length equal to or greater than N times the integer number and having N print media mounted and held thereon, and dot recording on each pixel of the reference length print medium is a recording head. The drum is rotated so that the printing medium moves in the sub-scanning direction with respect to the recording head at a double speed higher than the reference speed at a predetermined pixel density in the operation cycle, and each pixel is subjected to N-pass multipass printing with N rotations of the drum. A line dot recording apparatus configured to form an image on a printing medium by dot recording.   2. The line dot recording apparatus according to claim 1, wherein the speed equal to or higher than the reference speed is set to N times the reference speed in the sub-scanning direction of the print medium.   Head moving means for moving the recording head in the main scanning direction and the return direction with respect to the rotating drum is connected to the recording head, and the recording head is moved to N positions including a reference position with respect to the drum. The line dot recording apparatus according to claim 1, wherein an image is formed by operating a recording element corresponding to a dot recording area of the printing medium.   A sheet feeding means for feeding the rotating drum at a predetermined feeding position at a predetermined number of rotations of the rotating drum, a means for mounting / holding N print media on the rotating drum, and a predetermined printing medium The rotating drum is provided with a discharging means for removing and discharging the rotating drum at a predetermined number of rotations at a predetermined discharging position, and feeding, mounting and holding a plurality of print media to the rotating drum sequentially at a predetermined timing. 3. The line dot recording apparatus according to claim 1, wherein the line dot recording apparatus discharges the paper and continuously forms images of the same quality on a plurality of print media.   A sheet feeding means for feeding the rotating drum at a predetermined feeding position at a predetermined number of rotations of the rotating drum, a means for mounting / holding N print media on the rotating drum, and a predetermined printing medium The rotating drum is provided with a discharging means for removing and discharging the rotating drum at a predetermined number of rotations at a predetermined discharging position, and feeding, mounting and holding a plurality of print media to the rotating drum sequentially at a predetermined timing. The line dot recording apparatus according to claim 3, wherein the line dot recording apparatus is configured to discharge and form images of the same quality continuously on a plurality of print media.   While feeding, mounting, holding, and discharging the plurality of print media, dots are recorded by the recording elements in the same print image order for each pixel for each N print media, and printing of the N print media is performed. 6. The line dot recording apparatus according to claim 4, wherein the images are formed so that the image order is the same.   During feeding, loading, holding, and discharging of the plurality of print media, dots are recorded with a recording element using the same nozzle for each pixel for each of the N print media, and a print image of the N print media is recorded. 6. The line dot recording apparatus according to claim 4, wherein an image is formed with the same nozzle.   When the recording head is moved to N positions including the reference position in the main scanning direction and the return direction, the recording head is moved to the sequential position where the distances between adjacent positions are equal within the maximum moving distance in the main scanning direction. 6. The line dot recording apparatus according to claim 5, wherein a head moving means is connected to the recording head so as to be stopped and movable by a distance capable of forming a plurality of predetermined print images.   2. The recording head according to claim 1, wherein a plurality of recording elements correspond to each pixel at each of N positions, and an even-numbered element or an odd-numbered element is configured to be capable of dot recording at each position. The line dot recording apparatus in any one of thru | or 8.   9. The apparatus according to any one of claims 4 to 8, wherein the rotating drum is configured to perform sheet feeding by the sheet feeding unit and sheet discharging by the sheet discharging unit once every (1 + 1 / N) rotation of the drum. A line dot recording apparatus according to any one of the above.   The print medium is a long sheet N times as long as the maximum standard size paper in the sub-scanning direction, and N sheets of images formed on the maximum standard size paper are formed for each long paper. The line dot recording apparatus according to claim 1, wherein the line dot recording apparatus is a line dot recording apparatus.   A rotary drum having a predetermined outer peripheral length capable of mounting a print medium on the outer periphery and driven to rotate by drum driving means, and a predetermined recording element to be printed by a plurality of jet nozzle outlets in the vicinity of the outer periphery of the drum Recording heads arranged in a line in the main scanning direction at intervals corresponding to a predetermined pixel density in the printing area, and the rotating drum has a length in the sub-scanning direction of the print medium as a reference length, and two or more A drum having an outer peripheral length of N or more times that is an integer and having N print media mounted and held thereon, and printing dots by recording dots in each pixel by N-pass multi-pass printing with N rotations of the drum An image is formed on the rotating drum, and a sheet feeding unit that feeds the rotating drum at a predetermined sheet feeding position; a unit that mounts and holds N printing media on the rotating drum; At the paper output position. The sheet discharge means for discharging the sheet is provided for the rotating drum, and the sheet is fed by the sheet feeding means and discharged by the sheet discharging means for each (1 + 1 / N) rotation of the drum. Line dot recording device.

Images