JP6025355B2 - Inkjet recording apparatus and inkjet recording method - Google Patents

Description

  The present invention relates to an ink jet recording apparatus and an ink jet recording method, and more particularly to an ink jet recording apparatus and an ink jet recording method for recording an image on a recording medium by bidirectional recording.

  In an ink jet recording apparatus, a method of recording an image by scanning a predetermined recording area (band) a plurality of times in both directions (reciprocating directions) is known.

  When recording is performed by this method, the ink ejection order differs between a band starting from forward recording and a band starting from backward recording. For this reason, the color tone is different for each adjacent band, resulting in color unevenness, which may reduce the recording quality.

  The color unevenness can be suppressed by increasing the number of scans (pass number) for completing the recording of one band, but it takes time to complete an image when the number of scans is increased. Therefore, it is necessary to suppress the number of passes in order to prevent a decrease in recording speed.

  Therefore, Patent Document 1 discloses a recording method for eliminating the color unevenness by two-pass bidirectional recording in which one band is recorded by two reciprocating scans to complete an image. In the recording method described in Japanese Patent Laid-Open No. 2004-228561, the ink ejection order for each adjacent band is made uniform by changing the conveyance direction and conveyance amount of the recording medium after each reciprocating scan, and the difference in color (color unevenness) is obtained. It has been resolved.

Japanese Patent No. 3176130

  However, according to the recording method disclosed in Patent Document 1, it is necessary to frequently change the conveyance direction of the recording medium. If the conveyance direction of the recording medium is frequently changed, for example, the conveyance means may be rattled or the conveyance resistance applied to the recording medium may be different.

  The present invention has been made in view of the above problems. The object is to provide an ink jet recording apparatus and an ink jet recording method capable of eliminating the color unevenness caused by the ink ejection order without changing the transport direction of the recording medium in two-pass bidirectional recording in which recording is completed by reciprocating scanning. There is to do.

Therefore, in the present invention, a recording head in which a plurality of nozzle rows for ejecting different color inks to a recording medium is arranged, and a recording head alternately in the forward direction and the backward direction in the direction in which the plurality of nozzle rows are arranged. An ink jet recording apparatus comprising: a scanning unit that scans the recording medium; and a transport unit that transports the recording medium in the nozzle arrangement direction of the nozzle row between forward scanning and backward scanning. A natural number, N is the number of nozzles arranged in the nozzle row, p is the pitch of the nozzles in the nozzle row, and m + n nozzles positioned at the extreme end on the downstream side in the conveyance direction of the recording medium in the forward scanning ink so as not to eject from the ink from the backward in the scan in the transport direction of the recording medium upstream of the (m + n) located at the outermost end nozzles (where, n> 2n + m) Further comprising limiting means to avoid out, the conveying means, the forward conveyance amount after scanning conveying the recording medium such that the n × p, the transport amount after the reverse scan is (N-2n -M) The recording medium is conveyed so as to satisfy xp.

  According to the above configuration, in the two-pass bidirectional recording in which the recording is completed by reciprocating scanning, the color for each adjacent band caused by the different ink ejection order by aligning the ink ejection order for each adjacent band. Unevenness can be eliminated. Further, according to the above configuration, there is no need to change the conveyance direction of the recording medium. Therefore, in the ink jet recording apparatus according to the present invention, it is possible to eliminate color unevenness for each adjacent band caused by the ink ejection order without changing the conveyance direction of the recording medium.

1 is a schematic perspective view showing an ink jet recording apparatus according to a first embodiment. FIG. 3 is a schematic diagram illustrating a nozzle surface of the recording head according to the first embodiment. FIG. 2 is a block diagram illustrating a schematic configuration of a control unit of the recording apparatus according to the first embodiment. (A) And (b) is a figure for demonstrating recording operation and conveyance operation. It is a flowchart which shows the operation | movement which sets the conveyance amount correction value of 2nd Embodiment. It is an example of the data table which shows the correction value of the conveyance amount of 2nd Embodiment.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

(First embodiment)
First, the configuration of the ink jet recording apparatus 300 according to the first embodiment will be described. FIG. 1 is a schematic perspective view illustrating an ink jet recording apparatus 300 according to the present embodiment, and FIG. 2 is a schematic diagram illustrating nozzle surfaces 101 to 104 of recording heads 201 to 204 according to the present embodiment. As shown in FIG. 1, the ink jet recording apparatus 300 includes a recording unit 215, a transport roller 209, a transport roller 210, an auxiliary roller 211, and an auxiliary roller 212.

  The recording unit 215 performs recording by ejecting ink while reciprocating in the main scanning direction (x direction shown in FIG. 1) intersecting the conveyance direction (sub-scanning direction / y direction shown in FIG. 1) of the recording medium 214. Recording on the medium 214. The recording unit 215 is provided with a carriage 213, and a plurality of ink tanks 205 to 208 are mounted on the carriage 213 so that ink can be supplied to the plurality of recording heads 201 to 204 of the carriage 213. The ink tank 205 contains black ink (Bk), the ink tank 206 contains cyan ink (C), the ink tank 207 contains magenta ink (M), and the ink tank 208 contains yellow ink (Y). Has been.

  As shown in FIG. 2, the nozzle surfaces 101 to 104 of the plurality of recording heads 201 to 204 are provided with a plurality of ejection openings, respectively. A nozzle (recording element) 100 capable of ejecting ink is constituted by the ejection port and an ejection energy generating element (not shown). In the drawing, nozzle rows (printing element rows) each including eight nozzles 100 are arranged on a straight line. As shown in the figure, a plurality of printing element arrays are arranged along the main scanning direction (x direction shown in FIG. 2), and the arrangement direction of the printing elements constituting each printing element array is the sub-scanning direction (FIG. 2 along the y direction).

  Black ink is ejected from the nozzle on the nozzle surface 101, cyan ink is ejected from the nozzle on the nozzle surface 102, magenta ink is ejected from the nozzle on the nozzle surface 103, and yellow ink is ejected from the nozzle on the nozzle surface 104.

  The ink tanks 205 to 208 and the recording heads 201 to 204 of the present embodiment are configured to be detachably mounted on the carriage 213, but the present invention is not limited to this. That is, a cartridge in which the ink tanks 205 to 208 and the recording heads 201 to 204 are integrated may be mounted on the carriage 213. Further, a multi-color integrated head that can eject inks of a plurality of colors from a single recording head may be mounted on the carriage 213.

  The conveyance roller 209 and the conveyance roller 210 rotate while pinching the recording medium 214 to convey the recording medium 214 and also have a role of holding the recording medium 214. The auxiliary roller 211 and the auxiliary roller 212 assist the movement of the transport roller 209 and the transport roller 210. The conveyance roller 209 and the conveyance roller 210 are provided on the upstream side in the conveyance direction, that is, the paper feeding direction side, and the auxiliary roller 211 and the auxiliary roller 212 are provided on the downstream side in the conveyance direction, that is, the paper discharge direction side.

  Each of the rollers 209 to 212 is preferably a metal roller that is processed so that a large frictional force can be generated by forming fine irregularities on the surface in order to convey the recording medium 214 with high accuracy.

  Next, reciprocating scanning by the recording unit 215 will be described with reference to FIG. At the time of non-recording, the recording unit 215 is controlled to stand by at the home position h shown in FIG. When a recording start command is input, the recording heads 201 to 204 standing by at the home position h move away from the home position h in the main scanning direction (x direction shown in FIG. 1) together with the recording unit 215 (forward direction). Move to. Along with this movement, ink is ejected from the nozzles and recorded on the recording medium 214.

  The recording unit 215 that has moved to the recording area of the recording medium 214 ejects ink and records on the recording medium 214 while moving in the direction (reverse direction) approaching the home position h, which is the opposite direction. After the previous scan is completed and before the next scan starts, the transport roller 209 and the transport roller 210 rotate to transport the recording medium 214 in the transport direction. At that time, the auxiliary roller 211 and the auxiliary roller 212 assist the movement of the conveying roller 209 and the conveying roller 210.

  In this way, while the recording heads 201 to 204 are reciprocated along the x direction, the recording scan for ejecting ink from the nozzles and the operation for transporting the recording medium 214 in the transport direction are repeated. By doing so, recording is performed on the recording medium 214.

  The recording operation for ejecting ink from the recording heads 201 to 204 is performed when the head drivers 306 to 309 drive the recording heads 201 to 204 under the control of the control unit 301 described later. The operation of transporting the recording medium 214 is performed when the motor driver 304 drives the transport motor 310 and the transport roller 209 and the transport roller 210 rotate under the control of the control unit 301 described later.

  FIG. 3 is a block diagram illustrating a schematic configuration of the control unit 301 of the inkjet recording apparatus 300 according to the present embodiment. As shown in the figure, the inkjet recording apparatus 300 is connected to a data supply apparatus such as a host computer (hereinafter referred to as a host PC) 303 via an interface 302. The ink jet recording apparatus 300 includes a control unit 301, a motor driver 304, a motor driver 305, head drivers 306 to 309, a transport motor 310, a carriage motor 311, and recording heads 201 to 204.

  The control unit 301 is for controlling the motor driver 304, the motor driver 305, and the head drivers 306 to 309. Various data, control signals related to recording, and the like are input from the host PC 303 to the control unit 301 via the interface 302. Then, the control unit 301 controls the motor driver 304, the motor driver 305, and the head driver 306 according to the control signal. In addition, the control unit 301 processes the input recording data.

  The motor driver 304 drives the transport motor 310, and the motor driver 305 drives the carriage motor 311. The conveyance motor 310 rotates the conveyance roller 209 and the conveyance roller 210 for conveying the recording medium 214. As the transport roller 209 and the transport roller 210 rotate, the recording medium 214 is transported in the direction of the arrow y, which is a fixed direction. The carriage motor 311 is for reciprocating the carriage 213 on which the recording heads 201 to 204 are mounted in the main scanning direction (x direction).

  The head drivers 306 to 309 are for driving the recording heads 201 to 204, and each correspond to one recording head. That is, a plurality of head drivers are provided corresponding to the number of recording heads. Control of the nozzles of the recording heads 201 to 204 is performed by the head drivers 306 to 309 driving the recording heads 201 to 204 under the control of the control unit 301.

  4A and 4B are diagrams for explaining the recording operation and the conveying operation of the present embodiment. As described with reference to FIG. 2, the recording head according to the present embodiment has four color recording heads arranged therein. However, for convenience of explanation, here, the recording operation of the recording head of one color (recording head 202) will be described with reference to FIG. Therefore, in the actual recording operation, recording is performed by reciprocal scanning according to the color order shown in FIG. 2, and C → Y and Y → C shown in FIG. 4A indicate the ink ejection order in the actual recording operation. ing.

  The present embodiment is a two-pass bidirectional recording in which one band is recorded to complete an image by performing scanning once each in the forward direction and the backward direction.

  The recording head 202 of this embodiment has nozzles N1 to N8. One square in FIG. 4A shows one nozzle, and the width thereof is the same as the nozzle pitch 105 shown in FIG. Recording operations 401 to 404 each indicate a recording operation. White squares indicate that the nozzles are restricted (no ink is ejected), and black squares indicate that the nozzles are not restricted (ink is ejected).

  The nozzle N1 is on the downstream side in the transport direction (the paper discharge side / auxiliary roller 211 and auxiliary roller 212 side), and indicates the first nozzle counted from the downstream side. That is, the nozzle N1 is a nozzle located at the endmost portion on the downstream side in the transport direction. The nozzle N8 is on the upstream side in the transport direction (the paper feed side / the transport roller 209 and the transport roller 210 side), and indicates the eighth nozzle counted from the downstream side. That is, the nozzle N8 is a nozzle located at the extreme end on the upstream side in the transport direction. Areas 405 to 407 indicate areas where recording is completed.

  Next, actual recording operation and conveyance operation will be described. In general, the side where the home position h and the recording medium 214 shown in FIG. Therefore, in order to minimize the scanning distance, it is desirable to start the first recording operation from the home position h side. A description will be given with reference to FIG.

  First, the recording unit 215 performs a recording operation 401 while performing forward scanning. At this time, among the nozzles located on the downstream side of the nozzles N1 to N8 of the recording head 202, the nozzle located on the most downstream side and the nozzle adjacent thereto are limited. When the recording unit 215 reaches the reverse recording start end, the recording medium 214 is conveyed by the length of one nozzle in the direction of the arrow y.

  After the recording medium 214 is conveyed, the recording unit 215 performs a recording operation 402 while performing backward scanning. At this time, among the nozzles located upstream of the nozzles N1 to N8 of the recording head 202, the nozzle located most upstream and the nozzle adjacent thereto are limited.

  When the recording unit 215 reaches the forward recording start end, the recording medium 214 is conveyed by the length of five nozzles in the conveying direction. After the recording medium 214 is conveyed, the recording unit 215 performs a recording operation 403 while performing forward scanning. At that time, the nozzles of the same position and number as in the recording operation 401 are limited. When the recording unit 215 reaches the reverse recording start end, the recording medium 214 is conveyed by the length of one nozzle in the conveying direction.

  After the recording medium 214 is conveyed, the recording unit 215 performs a recording operation 404 while performing backward scanning. At that time, the same number of nozzles as in the recording operation 402 are controlled. When the recording unit 215 reaches the forward scanning start end, the recording medium 214 is conveyed by the length of five nozzles in the conveyance direction. Thus, recording is performed on the recording medium 214 by repeating the recording operation and the conveying operation.

  In the area 405, the recording operation 401 and the recording operation 402 are recorded in this order. That is, the forward recording (C → Y) and the backward recording (Y → C) are recorded in this order. In the area 406, the recording operation 401 and the recording operation 404 are recorded in this order. Also in this case, recording is performed in the order of forward recording (C → Y) and backward recording (Y → C). Further, in the area 407, since recording is performed in the order of the recording operation 403 and the recording operation 404, recording is performed in the order of forward recording (C → Y) and backward recording (Y → C). Therefore, in any of the areas 405 to 407, the order of recording the inks matches.

The above recording operation is expressed as follows. If m and n are arbitrary natural numbers, the number of nozzles restricted in forward recording and the number of nozzles restricted in backward recording are m + n (where N> 2n + m) .

In the present embodiment, since the number of nozzles to be limited is two, m = 1 and n = 1. When the nozzle pitch 105 is p and the number of nozzles arranged in the nozzle row is N, the transport amount of the recording medium 214 after forward recording (after forward scanning) is n × p, and the recording medium after reverse recording conveyance amount 214 is (N-2n-m) × p. In addition, m × p is the length of the region 406.

  FIG. 4B is a diagram showing an area where the recording is completed by the recording operation and the transport operation described above. In this embodiment, since the ink ejection order is uniform in all the areas 405 to 407, as shown in the figure, a recorded matter having no difference in color can be obtained in all the areas. Therefore, in the present embodiment, it is possible to eliminate color unevenness caused by the ink ejection order without changing the conveyance direction of the recording medium.

  In the present embodiment, the recording heads 201 to 204 each having eight nozzles have been described. However, the present invention is not limited to this, and a longer recording head may be used. For example, even when a 2-inch recording head configured with a nozzle length of 2400 nozzles and a nozzle pitch of 1200 dpi is used as a long recording head, the same effects as in the present embodiment can be obtained as long as the above formula is satisfied. .

  In the present embodiment, all the areas 405 to 407 can be recorded in the order of forward recording and backward recording by the method described above. Therefore, there is no bias in the order in which ink is recorded, and the occurrence of color unevenness due to the order in which ink is recorded can be eliminated. In the present embodiment, it is not necessary to change the conveyance direction of the recording medium 214 for each recording scan. Therefore, in this embodiment, it is possible to eliminate color unevenness for each adjacent band caused by the ink ejection order without changing the conveyance direction of the recording medium 214.

  Further, in this embodiment, since it is not necessary to change the transport direction, for example, rattling occurs in the transport means, a difference occurs in transport resistance applied to the recording medium, and control is complicated. There is no.

(Second Embodiment)
In the present embodiment, in the recording control of the first embodiment, when the recording medium is in a condition that is slippery during conveyance, the conveyance amount of the recording medium is corrected based on the condition. Since other configurations and operations are the same as those in the first embodiment, the description thereof is omitted. In this embodiment, the type and size of the recording medium are described as examples of the condition that the recording medium is slippery. However, there is a factor that causes an error in a desired conveyance amount of the recording medium under other conditions. If there is, the conveyance amount of the recording medium may be corrected accordingly. For example, the conveyance amount of the recording medium may be corrected according to the environmental conditions of the ink jet recording apparatus.

  FIG. 5 is a flowchart illustrating an operation of setting a correction value for the carry amount according to this embodiment. FIG. 6 is an example of a data table showing correction values for the carry amount according to the present embodiment. As shown in FIG. 5, recording starts when a recording command is input by the user to the host PC 303 (S501). Next, the selected recording mode is determined (S502). In the present embodiment, the recording mode is the recording mode described with reference to FIG. 4A of the first embodiment. Next, the type and width of the recording medium 214 are determined (S503). The type and width of the recording medium 214 are determined based on information input to the host PC 303 by the user.

  Based on these results, a correction value for the conveyance amount of the recording medium 214 is determined. Therefore, a data table (correspondence relationship) stored in a predetermined memory in the inkjet recording apparatus 300 is referred to (S504). Details of the data table will be described later. By referring to this data table, a correction value suitable for the recording medium 214 is determined (S505).

  As shown in FIG. 6, in the data table, a correction value corresponding to the type of the recording medium 214 is set for each width of the recording medium 214 after the forward recording and after the backward recording. FIG. 6 illustrates plain paper, coated paper, and glossy paper as types of the recording medium 214. Specific correction values will be described with reference to FIG. First, when the type of the recording medium 214 is plain paper, the conveyance amount correction value after forward recording is 0 when the width of the plain paper is large, and 1 when the width of the plain paper is small. It is. On the other hand, the correction value of the conveyance amount after the reverse recording is 2 when the width of the plain paper is large and 4 when the width of the plain paper is small.

  Next, when the type of the recording medium 214 is coated paper, the correction value of the conveyance amount after forward recording is 0 when the width of the coated paper is large, and when the width of the coated paper is small. 1. On the other hand, the correction value of the conveyance amount after the reverse recording is 2 when the width of the coated paper is large, and is 4 when the width of the coated paper is small. When the type of the recording medium 214 is glossy paper, the correction value of the conveyance amount after forward recording is 1 when the width of the glossy paper is large, and is 2 when the width of the glossy paper is small. . On the other hand, the correction value of the conveyance amount after the reverse recording is 4 when the width of the glossy paper is large and 8 when the width of the glossy paper is small.

  As described above, the correction value for glossy paper is set larger than the correction value for plain paper and coated paper. This is because the surface of glossy paper that uses a resin layer made of polyethylene as a base material is smoother than the surface of plain paper or coated paper based on paper, and is slippery during transportation. .

  In any type of recording medium 214, the correction value is set larger when the width of the recording medium 214 is smaller than when the width of the recording medium 214 is large. This is because when the width of the recording medium 214 is small, the portion of the recording medium 214 that is sandwiched between the conveyance roller 209 and the conveyance roller 210 is small, and thus the recording medium 214 is easily slipped. This phenomenon that the recording medium easily slips easily occurs particularly when a recording medium having a shape in which the recording medium is wound around a cylindrical member is used.

  Further, in this embodiment, as described in the first embodiment, the transport distance of the recording medium 214 after forward recording and the transport distance of the recording medium 214 after backward scanning are different, so that after the forward recording and after the backward recording. And the slip amount and slip ratio of the recording medium 214 are also different. In addition, the position (positional relationship) between the recording unit 215 and the recording medium 214 may be different after the forward recording or after the backward recording due to the influence of the deflection of the conveying means or the deflection of the recording medium. In this case, the landing position of the ink droplet ejected from the nozzle on the recording medium 214 is shifted.

  In consideration of the above, in the present embodiment, the correction value at the time of conveyance after the reverse recording is set larger than that at the time of conveyance after the forward recording, based on the numerical value obtained from the experimental result.

  The correction value setting will be described with an example. For example, when the type of the recording medium 214 is plain paper and the width is large, the conveyance amount correction value after the forward recording shown in FIG. 6 is 0, so the conveyance amount is not corrected and the conveyance after the recording operation 401 is performed. The amount is conveyed by the length of one nozzle in the y direction.

  Next, for the conveyance amount after the recording operation 402, the correction value of the conveyance amount after the reverse recording shown in FIG. 6 is 2, so that the conveyance amount for the length of 5 nozzles in the y direction is 9600 dpi. The recording medium 214 is transported at a distance obtained by adding 2 dots depending on the unit. In this way, by correcting the transport amount, an error in the transport amount due to slipping of the recording medium 214 or the like is corrected. The above correction of the conveyance amount is performed by the motor driver 304 driving the conveyance motor 310 under the control of the control unit 301.

  In the present embodiment, since the conveyance amount of the recording medium 214 is corrected, an error in the conveyance amount of the recording medium 214 can be further eliminated as compared with the configuration of the first embodiment. Therefore, also in the present embodiment, it is possible to eliminate color unevenness for each adjacent band caused by the ink ejection order without changing the conveyance direction of the recording medium 214.

101-104 Nozzle surfaces 201-204 Recording head 300 Inkjet recording apparatus 301 Control unit

Claims (6)

A recording head in which a plurality of nozzle rows for discharging different color inks to the recording medium are arranged, and a scanning unit for alternately scanning the recording head in the forward direction and the backward direction in the direction in which the plurality of nozzle rows are arranged, and An inkjet recording apparatus comprising: a transport unit configured to transport the recording medium in a nozzle array direction of the nozzle row between forward scan and backward scan;
m and n are arbitrary natural numbers, N is the number of nozzles arranged in the nozzle row, p is the pitch of the nozzles in the nozzle row, and in the forward scanning, at the most downstream end in the transport direction of the recording medium ink so as not to eject the (m + n) nozzles positioned, the (m + n) of the nozzle located in the outmost portion of the upstream side in the transport direction of the recording medium in the backward scan (where, n> 2n + m) do not eject ink from Further comprising a limiting means to
The transport means transports the recording medium so that the transport amount after the forward scan is n × p, and the recording medium so that the transport amount after the backward scan is (N−2n−m) × p. An ink jet recording apparatus for conveying a medium.   The ink jet recording apparatus according to claim 1, wherein the transport unit corrects the transport amount after the forward scan and the transport amount after the backward scan according to an environmental condition of the ink jet recording apparatus.   The inkjet recording apparatus according to claim 1, wherein the transport unit corrects the transport amount after the forward scan and the transport amount after the backward scan according to the type of the recording medium. A scanning step of alternately scanning a recording head in which a plurality of nozzle rows for discharging inks of different colors onto a recording medium are arranged in the forward direction and the backward direction in the direction in which the plurality of nozzle rows are arranged;
A conveying step of conveying the recording medium in the nozzle array direction of the nozzle row between the forward scan and the backward scan;
An inkjet recording method comprising:
m and n are arbitrary natural numbers, N is the number of nozzles arranged in the nozzle row, p is the pitch of the nozzles in the nozzle row, and in the forward scanning, at the most downstream end in the transport direction of the recording medium ink so as not to eject the (m + n) nozzles positioned, the (m + n) of the nozzle located in the outmost portion of the upstream side in the transport direction of the recording medium in the backward scan (where, n> 2n + m) do not eject ink from Further including a limiting step to
In the transporting process, the recording medium is transported so that the transport amount after the forward scanning is n × p, and the recording is performed so that the transport amount after the backward scanning is (N−2n−m) × p. An ink jet recording method comprising conveying a medium.   5. The ink jet recording method according to claim 4, wherein, in the transporting step, the transport amount after the forward scan and the transport amount after the backward scan are corrected according to environmental conditions of the ink jet recording apparatus.   5. The ink jet recording method according to claim 4, wherein, in the transporting step, the transport amount after the forward scan and the transport amount after the backward scan are corrected according to the type of the recording medium.

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