JP3637345B1 - Line dot recording device - Google Patents

Abstract

The throughput (printing time per sheet) generated when a printing medium is moved by a rotating drum and image formation is performed by multipass dot recording in a predetermined printing area is reduced (time is increased). It is an object of the present invention to provide a line dot recording apparatus that can solve the problem and efficiently form a high-quality image on a plurality of print media.
A line dot recording apparatus A includes a nozzle head 1 having a recording element using a large number of ink-jet ink discharge ports (nozzles) as a recording head, and a rotating drum provided with an outer peripheral surface in proximity thereto. 2, a paper feeding means 3 for feeding paper to the drum, a mounting / holding means 4 for mounting and holding four sheets of paper on the drum, and a paper discharging means 5 for discharging the paper. This is a four-pass multi-pass method in the scanning direction, and the drum is rotated at a quadruple speed to form an image by four rotations, so that a reduction in throughput is eliminated and a high-quality image can be obtained.
[Selection] Figure 1

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 results in non-uniform distances between adjacent dots, high density at close locations, low density at distant locations, white streaks and the like, and image quality degradation.

  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 the third rotation, a blank portion in the main scanning direction is recorded in the fourth rotation, and in a sub scanning direction in the fourth rotation. 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, when 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 per sheet (printing time) 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 very 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 moved at such a low moving speed that does not cause such various inconveniences, and at the same time a multi-pass dot at a high speed such as double speed or quadruple speed in the sub-scanning direction. Although it is conceivable to apply the recording method to a plurality of sheets mounted on a rotating drum, there has been no example of such a trial yet.
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 an object of the present invention 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 subject to provide

As a means for solving the above-described problems, the present invention has a predetermined outer peripheral length capable of mounting a print medium on the outer periphery, and a plurality of rotating drums that are driven to rotate by the drum driving means and are adjacent to the outer periphery of the drum. sub-scanning of a recording head arranged in the main scanning direction in a line shape at an interval corresponding to a predetermined pixel density in a predetermined print area to be printed recording element by the jet nozzle discharge opening, the rotary drum printing medium direction length as a reference length, a 2 or more N or more times the length outer peripheral length of an integer of that, mounting the N sheets of the print medium, the drum being held, the reference length of the drum was rotated so that the dots recorded for each pixel of the print medium a predetermined multiple speed print media reference speed which is a predetermined pixel density operation period of the recording head is moved in the sub-scanning direction relative to the recording head, the drum N rotation of the The N-pass printing in 査 direction than was constructed line dot recording apparatus to form an image on a print medium by dots recorded in each pixel.

  According to the line dot recording apparatus of the present invention having the above-described configuration, throughput is reduced (the printing time is increased) by a multi-pass method with respect to a predetermined printing area of a plurality of printing media mounted on a rotating drum. Therefore, it is possible to efficiently form a high-quality image without doing so. However, when the rotating drum is rotated at the reference speed and the recording head is dot-recorded so as to have a predetermined pixel density, each pixel in the sub-scanning direction is successively dot-recorded adjacent to each other. When the dot recording operation is performed by N-pass printing, dots are recorded every N pixel intervals, but N times are required to complete dot recording for all pixels, and throughput is reduced.

Therefore, when the N-pass printing operation is performed and the drum rotation speed is set to N times as a predetermined speed of the reference speed, the drum recording time for each pixel every N pixel intervals is 1 / N times, that is, the original recording speed is restored. Become. In this case, since dots are recorded by N-pass printing on one printing medium, the first and Nth pixels are dot-recorded on each printing medium for each rotation, and N rotations are performed. Thus, dots are recorded for all pixels. When N print media are mounted on the rotating drum, the length of one print medium in the sub-scanning direction is 1 / N of the drum 1 rotation length. Dot recording is performed on all pixels of the sheet.

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 performing the above-mentioned N sheets, N rotations, a predetermined double speed, and N-pass multi-pass printing. It is not a big thing.

In the above-described apparatus for applying the N-pass multi-pass printing method using the rotating drum as described above, mounting N printing media on the drum outer peripheral surface, and printing on the N printing media at a predetermined double speed and N rotations. In order to perform the dot recording continuously, it is necessary to provide a printing medium feeding means, a drum mounting / holding means, and a paper discharging means. 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, 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 activated for a plurality of print media, and dots may be recorded on the plurality of media in the same order as the print images, or an image may be formed. You may make it form an image with the same nozzle with respect to the print image of a printing medium. In either case, the obtained image has a uniform image quality on all of the plurality of print media.

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 at a predetermined pixel density at a predetermined double speed of the reference speed is rotated, 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 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.

  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 four sheets of standard size A ₃ , and mounting / holding means 4 for mounting and holding each of the four sheets on the drum peripheral surface. There are also 4 sets each. The rotary drum 2 is rotationally driven at a predetermined rotational speed and a constant speed by a drive motor (not shown).

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 discharge port is discharged, but the number of thinning nozzles may be two or more or irregular thinning such as one, two, two, and three.

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.

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).

  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. In addition, the operation time in one direction is about 0.3 seconds, and the time until stopping and reversing 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 rotary drum 2 rotates, the paper is fed by gently pressing it with the clamp 4b so that the middle of the paper does not rise from the outer periphery of the drum. It is done. 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.

Reference numeral 12 in FIG. 2 denotes a fulcrum shaft, which is a shaft that rotatably supports the wing frame 13 for mounting the above-described 10 sets of nozzle heads 1. 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.

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, 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 set to 3 dots. The setting of this distance is arbitrary. For example, if the number of nozzle discharge ports of the nozzle head increases, the number of the nozzles increases. Depending on, a large distance such as 5, 10, 100,..., 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 speed is about 0.1 G, the maximum movement distance is about 30 mm, the one-way operation time is about 0.3 seconds, and the stop reversal is performed. The time until the time is about 1.3 seconds, however, such a movement and stop mode is that the carriage moves at high speed and rapid acceleration / deceleration over the entire width of the paper in a conventional serial printer (see, for example, Patent Document 3). In contrast, 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. Accordingly, when the above-mentioned moving distance, acceleration / deceleration, operation time, etc. are set for N sheets other than N = 4, N rotation, N double speed, and N pass, they are optimally set according to the value of N. The

  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.

  The 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. In practice, the first sheet is printed on two sheets. Since printing is completed before the fourth rotation on the first and subsequent sheets starts, if printing is performed continuously in large quantities, the first sheet is ejected and then the next sheet is fed to that position. It will be possible to print. Accordingly, a case where a large amount of printing is performed in which paper is continuously supplied 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) at the nozzle No. 7 and 9, the pixel position 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 maximum standard size (A ₃ ) is mounted on the outer periphery of N (N = 4) drums. However, the 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. Will be able to.

  In the above-described embodiment, an example of printing by a 4-pass multi-pass method, a four-sheet-mounted rotary drum, quadruple speed, and four rotations is shown. However, the set number 4 is any number as long as it is an integer of 2 or more. In general, the setting number is represented 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 performed in the thinned-out state in the same manner as in the case of N = 2 or 3 when N = 2 or 3, and N In the case of = 5, ejection is performed in every fourth thinning state, and even if the number of N increases thereafter, the same thinning state as N = 5 may be used.

  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

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 Claw claw 4b Clamp 5 Paper discharge means 5a Paper discharge roller 5b Chain 5c Claw claw 6 Suction feed unit 6a Storage case 6b Suction arm 6x Shaft 7 Storage case

Claims (10)

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 and a recording head arranged in the main scanning direction in a line shape at an interval corresponding to a predetermined pixel density in the printing area of the rotary drum is the reference length a length in the sub-scanning direction of the print medium, 2 of their more a a is N times the length outer peripheral length of the integer, N sheets of the print medium is mounted, and the drum is held, the dot recording on the pixels of the reference length of the print medium is a recording head print media at a predetermined multiple speed reference speed at operation period becomes a predetermined pixel density rotates the drum so as to move in the sub-scanning direction relative to the recording head, multipath N paths in the sub-scanning direction at a N rotation of the drum Each pixel by printing Configured line dot recording apparatus to form an image on a printing medium by the dot recording.   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. 2. The line dot recording apparatus according to claim 1, wherein an image is formed by operating a recording element corresponding to an area to be recorded with dots on a 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. 2. The line dot recording apparatus according to claim 1 , wherein the line dot recording apparatus is configured to discharge and form images of the same quality continuously on a plurality of print media. Paper feeding means for feeding the rotating drum at a predetermined feeding position at a predetermined number of rotations of the rotating drum, means for mounting / protecting N printing 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 2, 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. line dot recording apparatus according to claim 3 or 4, characterized in that the image sequence is to form an image so as to respectively 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. it has to form an image Te in the same nozzle line dot recording apparatus according to claim 3 or 4, wherein. 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. is stopped, and a plurality of line dot recording apparatus according to claim 2 or 4, characterized in that the concatenation of the head moving means of the distance component movably recording head capable of forming a predetermined print image. Claim 2, wherein the recording head corresponding to a plurality of recording elements in each pixel at each position of the N position, and the even-numbered or odd-numbered elements configured freely dot recording operation for each position Or the line dot recording device of 4. 4. The apparatus according to claim 3, wherein the rotating drum is configured to perform sheet feeding by the sheet feeding unit and sheet discharging by the sheet discharging unit once for each ( 1 + 1 / N) rotation of the drum. The line dot recording apparatus according to any one of 8 . 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. line dot recording apparatus according to any one of claims 1 to 9, characterized in that the.

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