JP5238121B2 - Image forming apparatus - Google Patents

Description

The present invention relates to an image forming equipment to correct the positional deviation of the image formation occurring during the image formation to the image-forming material.

  Conventionally known liquid jet forming apparatuses that form information such as characters and images by ejecting a recording liquid from a recording head include a serial type image forming apparatus and a full line type image forming apparatus.

The former serial type image forming apparatus performs image formation by a carriage-mounted recording head while moving the carriage along the platen holding the image forming material (main scanning direction) and a direction orthogonal to the carriage moving direction ( form in the sub-scanning direction) forms the feed of the image forming material, or the form of a further carriage without the feed forms a Ri also sent to the sub-scanning direction of the image forming material also.

In the latter case, the recording head has a liquid ejection / discharge port (nozzle) in the main scanning direction, and image formation is performed while moving the recording head relative to the image forming material in the sub-scanning direction. It is a form to do.
In addition, there has been proposed an apparatus configured to perform not only single-color image formation but also color image formation by arranging a plurality of recording heads while taking the above-described form.

  FIG. 11A is a simplified diagram of the configuration of the conventional image forming apparatus disclosed in Patent Document 1, and is a serial type image forming apparatus that does not move the above-described image forming material in the sub-scanning direction.

In FIG. 11A, a carriage 82 having a recording head of another arrangement form to be described later is schematically shown by a two-dot chain line. As shown in FIG. 11A, serial type image formation is performed. In the apparatus 61, one rotation of a motor 63 in which a carriage 69 having recording heads 70, 71, 72, and 73 arranged to face the upper side of a fixedly mounted image forming material 80 is fixed to one of support members 68. A moving mechanism driving unit 62 in the main scanning direction having a pulley 65 on the shaft and a rotary encoder 64 on the other rotating shaft is disposed. The pulley 65 and a pulley 66 arranged to face the pulley 65 in the main scanning direction. By rotating the endless belt 67 that is bridged with the endless belt 67, the carriage 69 connected by the endless belt 67a can reciprocate in the main scanning direction. Further, the other end of the support member 68 has 79a connected to an endless belt 79 that reciprocates the support member 68 in the sub-scanning direction. One end of the endless belt 79 is a pulley 78 and the other is a motor 75. By rotating an endless belt 79 bridged with the pulley 77 by a moving mechanism driving unit 74 in the sub-scanning direction having a pulley 77 on one rotating shaft and a rotary encoder 74 on the other rotating shaft, The carriage 69 can reciprocate in the sub-scanning direction.

  With the configuration as described above, it is possible to perform image formation based on the scanning locus 81 while detecting the amount of movement of the carriage 69 in the main scanning direction or sub-scanning direction with respect to the image forming material 80.

  Next, FIG. 11B shows the details of the arrangement of the recording heads arranged on the carriage 69 and the method of correcting the heavy color shift shown in Patent Document 1, and FIG. 11 shows the recording heads of other arrangements. This will be described in (c).

FIG. 11 (b), at the established form of the recording head shown in Patent Document 1, for example, a color corresponding (K) color 70, (C) color 71, (M) color 7 2 and (Y) color 7 3 each color recording heads are arranged on the carriage 69 at equal intervals L ₂ in the main scanning direction.

In Patent Document 1, when the moving speed of the carriage 69 in the main scanning direction is V, each color recording head forms an image with an ejection time of L ₂ / V, thereby forming a heavy color of each recording head in the main scanning direction. A method for correcting the deviation is proposed. Further, in the multi-color shift of each recording head in the main scanning direction, a shift larger than the dot interval is delayed based on the timing signal of the rotary encoder 64 in the moving mechanism driving unit 62 in the main scanning direction. For a deviation smaller than the interval, a method of delaying based on a signal having a higher frequency than the timing signal has been proposed.

  Next, FIG. 11 (c) is different from the arrangement of the recording head disclosed in Patent Document 1, for example, (K) color 83, (C) color 84, (M) color 85, and (Y) color 86 corresponding to color. The color recording heads are arranged in the sub-scanning direction with a predetermined equal interval or substantially no interval in the sub-scanning direction. For example, the carriage 82 is supported by the support member 68 and the moving mechanism driving units 62 and 74 are arranged. Thus, it is possible to carry out scanning by returning the scanning locus 81 of the carriage 69.

  As described above, FIGS. 11B to 11C show a serial type image forming apparatus in which four head arrays are arranged in a predetermined direction.

FIG. 12A is a simplified diagram of the configuration of the conventional image forming apparatus disclosed in Patent Document 2, and is a full-line image forming apparatus that feeds and moves the above-described image forming material in the sub-scanning direction. .
As shown in FIG. 12A, the full-line type image forming apparatus 87 performs, for example, (K) color 95 and (C) color corresponding to the image forming material 80 conveyed from the upstream side in the conveyance direction. 96, a carriage 94 in which each color recording head of (M) color 97 and (Y) color 98 has a liquid ejection / discharge port (nozzle) in the main scanning direction and is arranged at a predetermined interval in the sub-scanning direction; A rotary encoder 93 is provided on the rotating shaft of one roller 89 and a motor 92 is provided on the rotating shaft of the other roller 90 for conveying the image forming material 80 in the sub-scanning direction below the recording head. 89 and 90 are bridged with an endless belt 91 and a conveying mechanism 88 on which the image forming material 80 is placed is disposed oppositely.

The image forming timing of each color recording head with respect to the image forming material 80 is set by the number of pulses of the rotary encoder 93.
With the above configuration, it is possible to perform image formation by driving the color recording heads arranged on the carriage 94 in accordance with the amount of movement of the image forming material 80.

  Next, FIG. 12A shows details of the recording head arrangement form arranged on the carriage 94 and the method of correcting the heavy color shift shown in Patent Document 2, and FIG. 12 shows other recording head arrangement forms. This will be described in b).

As shown in FIG. 12A, for example, (K) color 95 discharge ports (nozzles) 95h ₁ ... 95h _{n corresponding} to color are formed, and a (K) color head array of 95h ₁ ... 95h _n is formed. Each of the (K) color recording head 95 and the (C) color recording head 96, (M) color recording head 97, and (Y) color recording head 98 corresponding to the color similarly has a head row, and has a predetermined row. This is a full-line type image forming apparatus in which four head arrays formed in the direction (main scanning direction in this case) are arranged at predetermined intervals in the sub-scanning direction.

In Patent Document 2, the endless belt 91 includes a pair of rollers, a pick-up roller 99a and a pressure roller 99b, which are disposed so as to be sandwiched between the front and back sides of the endless belt 91. A method has been proposed for correcting the fluctuation in the conveyance distance caused by the uneven thickness and the roundness unevenness of the rollers 89 and 90.
There has also been proposed a method for generating a timing that cancels a detection error due to the eccentricity of the pickup roller 99a and the pressure roller 99b.

Next, FIG. 12 (b) is different from the recording head arrangement form of Patent Document 2 described above. For example, each color recording head, which has a predetermined overlap in the main scanning direction and is composed of two rows, is arranged in the sub-scanning direction. (K) colors 100A ₁ , 100A ₂ , 100A ₃ , 100B ₁ , 100B ₂ , 100B ₃ and (C) colors 101A ₁ , 101A ₂ , 101A ₃ , 101B ₁ , 101B ₂ , 101B ₃ and (M) colors 102A ₁ , 102A ₂ , 102A ₃ , 102B ₁ , 102B ₂ , 102B ₃ , and (Y) colors 103A ₁ , 103A ₂ , 103A ₃ , 103B ₁ , 103B ₂ , 103B ₃ A form having 24 head rows in the scanning direction and a form arranged on the carriage 94 is also possible.

In this case, the full line image formation is, for example, 100A ₁ h ₁ ... 1 0 0B ₃ h _{n at the} (K) color discharge ports (nozzles).
12A is a full-line image forming apparatus in which four head rows are arranged in a predetermined direction, and FIG. 12B is a full line in which 24 head rows are arranged in a predetermined direction. Type image forming apparatus.

Further, Patent Document 3 proposes a mechanism for preventing bending when a support member having a different expansion coefficient and a guide member are expanded and contracted by different amounts due to a temperature change in the carriage support member as described in Patent Document 1 above. Has been.
Patent No. 2812461 Patent No. 2918905 JP 2002-200810 A

  However, when the serial type image forming apparatus 61 shown in FIG. 11A is mounted with the carriage 82 as shown in FIG. 11C, the support member 68 that supports the carriage 82 is used. When slight bending occurs, for example, as shown in FIG. 13A, the carriage 82 draws a carriage movement trajectory 104 (indicated by a dotted line) that does not inherently bend, whereas 104α (indicated by a solid line). It moves by drawing a moving trajectory with a large deflection.

As shown in FIG. 13A, each head row in each color recording head of (K) color 83, (C) color 84, (M) color 85, and (Y) color 86 described above (FIG. 13 (a)). In this case, the recording head length, the recording head row length, and the image forming image length in the head row length are defined to be the same length). The locus 104, that is, near the center of the support member 68 in the main scanning direction without deflection, is substantially perpendicular to the main scanning direction (K) color 83i ₁ , (C) color 84i ₁ , (M) color 85i ₁ and (Y) The color 86i ₁ is image-formed, and on the other hand, the carriage movement locus 104α, that is, near the both sides in the main scanning direction in the portion where the support member 68 is bent, is substantially perpendicular to the main scanning direction. a (K) color 83i _2, (C) color 84 _2, an image forming (M) color 85i ₂ and (Y) color 86i _2.

For example, when a (Y) color 86i ₁ is formed on the (K) color 83i ₁ , the carriage 82 is moved a distance corresponding to three head lengths in the sub-scanning direction, and then the (K) color 83i _{1 is used.} By forming an image with the same delay time, a heavy color image is formed.

However, for example, (K) If on color 83i ₂ a (Y) color 86i ₂ to heavy color image forming, after the carriage 82 was distance movement of the head length three in the sub-scanning direction, the (K) color 83i ₂ and same delay time imaging to be heavy color image forming is not performed, the distance X of the image forming position shift (heavy color shift) occurs as shown in Figure 13 (b).

This is because the deflection of the carriage support member 68 causes the carriage movement locus 104α of the carriage 82 to be generated.
For example, the following description will be made on the assumption that an inclination of 100 μm occurs when the carriage 82 moves 100 mm.

The amount of inclination of the carriage 82 is 0.001 from tan θ = 100 μm / 100 mm.
If each color recording head of (K) color 83, (C) color 84, (M) color 85, and (Y) color 86 is formed with 300 dpi and 512 nozzles, the head row length is 25.4 mm / From 300 × 512, it is about 43 mm. The total number of the (K) color 83, (C) color 84, (M) color 85, and (Y) color 86 when assuming that the head row length = head length and the recording heads of each color are arranged without gaps. The head length is 172 mm.

From the above, as shown in FIG. 13A, in the case where the (Y) color 86i ₂ is formed on the (K) color 83i ₂ , the carriage 82 is set to each recording head length: y ₁ + y ₂ + y. ₃ = Heavy-color image formation is performed by moving by a distance of Y, that is, Y is 43 mm × 3 = 129 mm.
Accordingly, the deviation amount X in the main scanning direction in the formation of the heavy color image is tan θ × 129 mm = 89 μm.

If an image is formed by adding only the delay time of the recording head (Y) color 86 to X in order to correct the deviation amount Δx ₃ = X in the main scanning direction, it is on the carriage movement locus 104α. The (K) color 83i ₂ and the (Y) color 86i ₂ are corrected so as to form a heavy color image, but the (K) color 83i ₁ and the (Y) color 86i ₁ on the carriage movement locus 104 are corrected. On the other hand, a heavy color shift as indicated by 86'i ₁ occurs with respect to the (K) color 83i ₁ .

As described above, such a shift in the image forming position cannot be corrected only by the conventional technique disclosed in Patent Document 1 described above.
Further, as a conventional technique for preventing the bending of the support member 68 that supports the carriage 82, the above-described Patent Document 3 has been proposed. Providing a plurality of support members 68 for supporting the carriage 82 increases the cost, and further increasing the length of the support member 68 as the image forming material increases in size (increases in width). It is necessary, and a case where a sufficient effect cannot be obtained only by preventing the bending in the plurality of coupling mechanisms is also assumed.

Further, as shown in FIG. 12 of Patent Document 2 described above (a), for example a color corresponding (K) has a discharge port of the color 95 _{(nozzle) 95h 1 ... 95h n, 95h} 1 ... of 95h _n ( K) The (K) color recording head 95 in which the color head row is formed, and the (C) color recording head 96, the (M) color recording head 97, and the (Y) color recording head 98 corresponding to the color respectively. In full-line type image formation in which four head rows are arranged at predetermined intervals in the sub-scanning direction, and are arranged in a predetermined direction (in this case, the main scanning direction). It has a pick-up roller 99a and a pressure roller 99b which are a pair of rollers arranged so as to be sandwiched between the front and back of the endless belt 91, and the thickness unevenness generated in the manufacturing process of the endless belt 91 and the two rollers 89, 9
A method for avoiding periodic transport distance fluctuations due to zero roundness unevenness is proposed. There has also been proposed a method for generating a timing for canceling a detection error due to the eccentricity of the pickup roller 99a and the pressure roller 99b.

  According to Japanese Patent Laid-Open No. 2004-260688, when a variation in the thickness of the endless belt 91 in the manufacturing process and a periodic conveyance distance variation due to the roundness unevenness of the two rollers 89 and 90 are uniformly generated across the recording head width. Improvements will be made.

However, with the increase in the length of the recording head, the cause of deviation of the image forming position of the image forming material in the periodic conveyance distance fluctuation due to the unevenness in thickness and the unevenness in roundness is a head array (nozzle array) of the recording head. It is not always uniform in the main scanning direction. 12 For example, as shown in (b) (K) color recording heads 100A _1, 100A _2, 100A ₃ and 100B _1, of the 100B _2, 100B _3, the recording head _{100A 1, 100A 2, 100A 3} , a main scanning Even if there are different factors in the image forming position on the direction side, the conventional technique described in Patent Document 2 described above can only correct the same delay time for the recording heads 100A ₁ , 100A ₂ , and 100A _3. is there. That is, it is not possible to correct the recording head 100A _1, 100A _2, 100A deviation factor different image forming position in the main scanning direction with respect to ₃ (recording head 100A _1, 100A _2, 100A separate delay time every ₃₎ .

The recording heads 95... 98 in FIG. 12A are also replaced with, for example, the nozzle arrays 95h _{1 to} 95h _n in the head array of the recording head 95 by 95h _{1 to} 95h _a , 95h _{b to} 95h _c , 95h _{d to} 95h _e , and 95h _e . _f ... 95h _g , 95h _h ... 95h _i and 95h _j ... 95h _If the nozzle row is divided into six and corrected with an independent delay time for each nozzle row, the cause of the deviation of the image forming position that differs on the main scanning direction side Can be corrected, but such correction cannot be performed.

In view of this, the present invention provides an image in which an image forming position shift when an image is formed by relative movement between an image forming material and a recording head is corrected by discharging the recording head for each head row. and to provide a forming equipment.

In order to achieve the above object, the present invention provides a recording head having a nozzle row formed by a plurality of ejection nozzles arranged along a main scanning direction orthogonal to the conveyance direction of an image forming material for each ink color. A plurality of image forming units arranged in the conveying direction, an image forming material conveying mechanism arranged to be opposed to the plurality of nozzle rows and holding and conveying the image forming material, and the nozzle rows of the respective recording heads are predetermined. A plurality of head rows of each color divided by the number of ejection nozzles, and a plurality of transport speed detectors for detecting the transport speed of the image forming material transport mechanism corresponding to each of the head rows. In the line type image forming apparatus for forming a heavy color image on the image forming material conveyed by the nozzle rows of the plurality of recording heads arranged in the conveyance direction, the control unit includes a plurality of the conveyance In the image forming position relative deviation amount of each head row calculated by the detection result of a transporting speed of from degrees detection unit, based on the image forming position relative displacement amount of one head row, heavy color shift other heads column An image forming apparatus having a control unit that controls ink ejection timing so as to correct the above is provided.

According to the present invention, the deviation of the image forming position when being imaged by the relative movement between the recording head and the image-forming material, an image forming equipment to correct the deviation of the image forming position by the ejection control for each head row it is possible to provide a.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a conceptual configuration example in an embodiment of an image forming apparatus according to the present invention. As shown in FIG. 1, a head formed by a predetermined number of ejection nozzles is placed above a mounting table or a transport mechanism 2 on which an image forming material 1 is placed and fixed or held movably in a predetermined direction. recording head 4 or 6H 1 _... 6H _n having at least a plurality of columns are arranged opposite the on the image-forming material 1, the image formed by the relative movement of the object image forming material 1 and the recording head 4 or 6H 1 _... 6H _n It is the structure to do.

In FIG. 1, on the other hand, the recording head 4 is disposed on the moving body 3, and a moving mechanism (not shown) that supports the moving body 3 so as to be movable in a predetermined direction causes Hx _{0 to} Hx _n ( 2 shows a recording head of a serial type image forming apparatus that moves between (main scanning direction) and / or Hy _{0 to} Hy _n (sub-scanning direction), and on the other (shown by a two-dot chain line), A plurality of recording heads 6H ₁ ... 6H _n of a full-line image forming apparatus are provided that are arranged in a plurality of directions at a predetermined interval and have at least a nozzle row having a width equal to or larger than the width of the image forming material 1 in the main scanning direction.

In this full-line type image forming apparatus, the leading end portion 1 a in the sub-scanning direction of the image forming material 1 is moved between My _{0 to} My _n by the transport mechanism 2.
When the image forming material 1 and the recording head 4 or the recording head 4 or 6H ₁ ... 6H _n form an image and the image forming position deviation correction is necessary, the control unit 7 controls the image forming material / recording. the movement control of the head, said implement relative movement between the object image forming material 1 the recording head 4 or 6H 1 _... 6H _n, and the in the recording head 4 or 6H 1 _... 6H _n, discharge of each head lines The shift of the image forming position is corrected by the control.

  Next, a first embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings. The first embodiment of the present invention can be applied to a serial type image forming apparatus (first mechanism form) and a full line type image forming apparatus (second mechanism form).

As shown in FIG. 2, in the first embodiment, the control unit 11 having the plane memory 12 and the carriage 16 having the recording head or the moving body 16 that carries the image forming material (not shown) are conveyed. A moving mechanism 13 having a moving mechanism driving unit 14 and a moving position information generating unit 15 in movement, a discharge information generating unit 17 having a positional deviation information memory 18 of an image forming position, and a plurality of head arrays _{1... N} discharge timing circuit 22D. ₁ ... 22D _n and a timing generator 20 having a plurality of head rows _{1 ... n} discharge data memory _21M 1 ... _{21M n,} a plurality of heads column drive circuit _23D 1 ... _{23D n,} a plurality of the head arrays _24H 1 ... 24H _n Consists of

  The control unit 11 includes, for example, a CPU and the like, and controls the movement mechanism driving unit 14 in the movement mechanism 13, signal processing of the movement position information generation unit 15, signal processing of the ejection information generation unit 17, The image forming apparatus is comprehensively controlled such as signal processing for the timing generation unit 20 and storage of the image forming data 25 in the plane memory 12. Further, the moving mechanism drive unit 14 in the moving mechanism 13 is configured by, for example, a motor, and the moving position information generating unit 15 is configured by, for example, a rotary encoder. The movement position information generation unit 15 may include a high frequency generation circuit that multiplies the frequency of the pulse signal generated by the rotary encoder as an integral number as necessary. In addition, the ejection information generation unit 17 stores in advance in the misregistration information memory 18 image formation misregistration information (details will be described later) calculated by the image device 26 that is an external device of the image forming apparatus. Discharge information for each head row is generated based on the image forming position deviation information and then transmitted to the control unit 11.

Further, the timing generator 20, the 1-line image forming data at the head string transmitted from the control unit 11, temporarily stored in the head row _{1 ... n} discharge data memory 21M 1 _... 21M _n, and the control Based on the ejection timing correction value for each head row _{1... N} transmitted from the unit 11, the ejection timing for each head row _{1... N} is generated by the head row _{1... N} ejection timing circuit 22D ₁ . by driving the head column drive circuit _23D 1 ... _{23D n,} the deviation of the image forming position in the image formation is performed in the head array _24H 1 ... 24H _n is corrected. Incidentally, wherein the head row _{1 ... n} ejection timing circuit _22D 1 ... 22D _n, is composed of, for example, program delay circuit between Bull setting method or the like.

Next, an arrangement example of the image forming apparatus configured as described above in the serial type image forming apparatus (first mechanism form) will be described.
As shown in FIG. 3, the mechanism portion 32 of the serial type image forming apparatus has shafts that pass through two pairs of rollers 35 on the upstream side of the conveyance path along which the image forming material 31 is conveyed in the sub-scanning direction. An upper transport roller 33a (driven side) and a lower transport roller 33b (drive side), which are pivotally supported on both sides of 34a and 34b, are disposed substantially parallel to the main scanning direction. Both sides of the shaft 34a of the upper transport roller 33a are rotatably supported by bearings, and the lower transport roller 33b is supported by one of the shafts 34b of the lower transport roller 33b by a bearing and the other after passing through the bearing. By rotating the shaft 34b by the movement mechanism 36 having the motor 37 and the rotary encoder 38, the image forming material 31 is sandwiched between the two pairs of rollers 35 and is moved downstream in the sub-scanning direction. Move (convey).

  The edge of the image forming material 31 to be moved is detected by an edge sensor 31a, and the image formation start position is determined by the number of pulse signals generated by the rotary encoder 38 using the sensor 31a as a trigger.

For example, (K) color 24H ₁ head row ₁ corresponding to color, (C) color 24H ₂ head row ₂ and (M), which are opposed to the placement material 45 on which the image forming material 31 is placed. The carriage 16 in the moving body having each color recording head of the color 24H ₃ head row ₃ and the (Y) color 24H ₄ head row ₄ is moved in the main scanning direction by the support members 40 supported by the fixing members 39a and 39b on both sides. Supported as possible.

  The movement of the carriage 16 in the main scanning direction is such that an endless belt 43 bridged by a pulley 42 arranged one on the pulley 41 and the other on the pulley 41 connects the carriage 16 with a connecting portion 44a. The moving mechanism 13 having the motor 14 in the moving mechanism driving unit and the rotary encoder 15 in the moving position information generating unit is connected to the rotation shaft of the pulley 43, and the endless belt 43 is rotated to reciprocate in the main scanning direction. Is possible.

Next, an image forming position deviation correction method will be described using a serial type image forming apparatus as an example.
In this description, description will be made with reference to FIGS. 3 to 4 and FIGS. 13 (a) to 13 (b).

The image device 26 that is an external device of the image forming apparatus according to the first embodiment includes an image processor including a scanner and a computer, for example.
The image device 26 reads an image forming material 31 on which a predetermined image forming pattern has been formed before the image formation position deviation correction by a scanner in the image device 26, and is image formation position deviation information from the read image. The coordinates on the image forming material 31 at the position where the image forming position is shifted and the shift amount in the main scanning direction at the coordinates are calculated.

The predetermined image forming pattern is, for example, a head row _{1... 4} in each color recording head of (K) color 24H ₁ , (C) color 24H ₂ , (M) color 24H ₃ and (Y) color 24H _{4 corresponding} to color _. However, in the process of performing one scan in the main scanning direction, first, (K) color 24H ₁ head row ₁ (nozzle row ₁ ) among the color recording heads arranged linearly in the sub-scanning direction, a predetermined pitch interval. (For example, 25.4 mm / 300 dpi = about 85 μm), and forming a line in the sub-scanning direction with all nozzles at a head row (nozzle row) length (for example, 85 μm × 512 = about 43 mm for 300 dpi 512 nozzles) at intervals of several pitches (For example, dot diameter: 85 μm × √2 = about 120 μm), and then the carriage 16 is moved in the sub-scanning direction by the moving mechanism 13 with each color recording head length: 43 mm (in the first embodiment, recording is performed). Head length = head Column is defined as (the nozzle row) in length.) Was followed, by imaging at (C) color 24H ₂ from the head array ₂ (K) color 24H ₁ same ejection timing as a head array ₁ (no correction), In the recording head (K) color 24H ₁ head row _{1 in the} image formation position of the recording head (C) color 24H ₂ head row ₂ , the predetermined image forming pattern is formed.

In the same procedure, the recording head (K) color 24H ₁ head row _{1 is} formed by the recording head (M) color 24H ₃ head row _{3 at the} image forming position, and the recording head (K) color 24H ₁ head row ₁ is used. The predetermined image forming pattern is image-formed by the formation of a heavy color image by the (Y) color 24H ₄ head row _{4 at the} image forming position.

  FIG. 13A shows the calculation of the main scanning direction coordinates on the image forming material 31 where the image forming position is shifted as the image forming position shift information and the shift amount in the main scanning direction at the coordinates. For example, an image forming material on which a heavy color image is formed by the recording head (Y) color 86 with respect to the entire image forming area (the carriage movement locus 104α) in the main scanning direction of the recording head (K) color 83 is, for example, For example, by extracting (Y) color by the image processor of the image device 26, the main scanning direction coordinates of the position where the image forming position is shifted on the carriage movement locus 104α and the coordinates are shown in FIG. 13B. The image forming position deviation amount X in the main scanning direction is calculated.

  The coordinates of the position where the image forming position is shifted and the image forming position shift amount at the coordinates calculated by the image device 26 are stored in the position shift information memory 18 of the ejection information generating unit 17.

  The ejection information generation unit 17 is calculated by the image device 26 in an area where the carriage movement locus 104 and the carriage movement locus 104α do not overlap as shown in FIG. As shown in FIG. 4, the image forming position deviation amount at the coordinates of the plurality of positions where the plurality of image forming positions is shifted is stored in the position deviation information memory 18 as a data table as shown in FIG. Preparation for deviation correction is completed.

The present invention can also be applied to the second mechanism form (full line type image forming apparatus) of the image forming apparatus as shown in FIG. 12 (a), and the head of the recording head 95 in FIG. 12 (a). The nozzles 95h ₁ ... H _n in the row are divided into, for example, six head rows with a predetermined number of nozzles, and the relative image forming position deviation between the six head rows is shown in the data table as shown in FIG. By registering it in the misregistration information memory 18, it is possible to correct misregistration for image formation.

Or a recording head (K) colors 100A ₁ ~100A ₃ and 100B ₁ ~100B ₃ of the aforementioned Figure 12 (b), and (C) color 101A ₁ ~101A ₃ and 101B ₁ ~1001B _3, (M) color 102A ₁ -102A ₃ and 102B _{1 to} 102B ₃ and (Y) colors 103A _{1 to} 103A ₃ and 103B _{1 to} 103B ₃ are also corrected for, for example, the image formation positional deviations of 100A ₂ to 100A ₃ with respect to (K) color 100A ₁ Next, after correcting the image forming position deviations of 100B ₂ to 100B ₃ for (K) color 100B _1, (C) colors 101A _{1 to} 101A ₃ and (M) color 102A for (K) colors 100A _{1 to} 100A ₃ are corrected. _{1 to} 102A ₃ and (Y) colors 103A _{1 to} 103A ₃ are corrected, and (C) color 101 for (K) colors 100B _{1 to} 100B ₃ FIG. 4 shows the relative image forming position shifts between the head rows so that the corrections of B _{1 to} 101B ₃ , (M) colors 102B _{1 to} 102B ₃ and (Y) colors 103B _{1 to} 103B ₃ are performed. As shown in the table, the data table is stored in the misregistration information memory 18 so that the image misregistration misregistration can be corrected. A pick-up roller 99a and a pressure roller 99b, which are a pair of rollers disposed so as to be sandwiched between the endless belt 91, are provided. In addition to the effect in the method of correcting the variation in the transport distance, it is possible to correct the image formation deviation factor in the main scanning direction.

Next, a processing method when the image forming data 25 is stored in the plane memory 12 of the control unit 11 and the image forming positional deviation correction is actually started will be described.
The control unit 11 sandwiches the image forming material 31 shown in FIG. 3 between the upper transport roller 33a and the lower transport roller 33b, and moves (transports) it in the sub-scanning direction by driving control of the moving mechanism 36. The image forming material 31 is moved to the image formation start position according to the number of pulse signals generated by the rotary encoder 38 using a signal obtained by detecting the edge of the forming material 31 by the sensor 31 a as a trigger, and from the plane memory 12. Each color image formation data for one scan is stored in (K) color head row ₁ discharge data memory 21M ₁ , (C) color head row ₂ discharge data memory 21M ₂ , and (M) color head row ₃ discharge data memory in FIG. 21M ₃ and (Y) are transmitted to the color head column ₄ discharge data memory 21M ₄ stores.

The control unit 11 controls the movement of the moving mechanism 13 so that the (K) color 24H ₁ disposed on the carriage 16 in the moving body is a (K) color image at a predetermined discharge timing (the number of pulse signals generated by the rotary encoder 15). Perform formation. In this case the (K) color head array ₁ set ejection timing circuit 22D ₁ (variable amount) is 0 (zero), it is corrected relative to the (K) color 24H _1.

When the formation of the (K) color image is completed, the control unit 11 drives and controls the moving mechanism 13 to return the carriage 16 to the image start position, and controls the moving mechanism 36 for one head length. The image forming material 31 is moved by a distance. (In the first embodiment, the gaps between the color recording heads arranged in the carriage 16 in the sub-scanning direction are defined as zero.)
Next, the control unit 11 forms an image due to the bending of the support member 40 of the carriage 16 or the like in the heavy color image formation on the (K) color image formation of the image forming material 31 in the (C) color. the (CΔx _n for CΔx 1 _... Cx _n for Cx ₁₎ ejection correction data for correcting the positional deviation, the variable amount is set in the aforementioned Figure 4 read from the data table, wherein (C) color head _two rows ejection timing circuit 22D ₂ The

Note that at this time (M) color and (Y) colors also reads each ejection correction data at the same time, (M) color head _three rows discharge circuit 22D ₃ and (Y) respectively variable color head ₄ columns discharge circuit 22D ₄ The amount may be set, or may be read and set before the formation of the heavy color image on the (K) color image formation.

The ejection correction data is based on an empirical value that the amount of image formation position deviation that needs to be corrected is 1/8 pitch or more, and the amount of deviation of 1/8 dot or more at a pitch of 85 μm in the above-described 300 dpi image formation, for example. Becomes a correction target and becomes about 11 μm or more.
Accordingly, the rotary encoder 15 in the moving mechanism 13 needs to generate ejection timing in image formation of at least 2400 dpi.

  As a method not using such a relatively high-resolution rotary encoder, for example, an encoder signal generated at a dot interval in the main scanning direction is converted into a high-frequency signal using an N-times (integer multiple) high-frequency generation circuit. There is a way to control. For example, if the N-fold high-frequency generation circuit generates an 8-fold high frequency and performs discharge control, the image formation pitch at the discharge timing per step: 85 μm × 1/8 = about 11 μm can be corrected and controlled.

  Next, a correction method in the formation of a multicolor image of another color recording head on the (K) color image formation of the image forming material 31 will be described with reference to the conceptual diagram, taking the 8 × high frequency generation circuit in the N-fold high frequency generation circuit as an example. To do.

  FIG. 5A shows an ejection timing generation method in a conventional 8-fold high frequency generation circuit, and is shown in a timing chart when a carriage having a recording head moves from the left to the right (main scanning direction) in the drawing. ing.

  The first stage is “encoder signal”, the second stage is “converted to eight times high frequency” by the eight times high frequency generation circuit based on the encoder signal, and the third stage is “discharge timing 0”. / 8T ", the fourth row shows" dispensing the ejection timing by 1 / 8T ". The period T of the “encoder signal” indicates the ejection timing of 1-dot ejection in the recording head, and the “ejection timing 0 / 8T” is shifted by the ejection timing after conversion to 8 times higher frequency in the “encoder signal”. The state of quantity 0 (zero) is shown. In addition, “shift the ejection timing by 1 / 8T” indicates a state in which the ejection timing is shifted by 1 / 8T with respect to the “encoder signal” cycle T.

  As described above, according to the prior art, in the ejection timing change of 1 dot or less when the carriage having the recording head moves from the left to the right (main scanning direction), 1 dot or less in a certain period T during the carriage movement. The discharge timing can be changed.

Next, FIG. 5B shows an ejection timing generation method in the 8-fold high-frequency generation circuit of the present invention. The timing at the first stage when the carriage having the recording head moves in the right direction (main scanning direction) from the left in the figure. Is the "encoder signal", the second stage is "converted to an eight-fold high frequency" converted to an eight-fold frequency by the eight-fold high-frequency generating circuit based on the encoder signal, the third stage is "eject timing is 1 / 8T “From the shifted state, the ejection cycle T (1T) is converted to 7 / 8T in the middle”. The period T of the “encoder signal” indicates the ejection timing of 1-dot ejection in the recording head, and “the ejection period T is converted to 7 / 8T in the middle from the state where the ejection timing is shifted by 1 / 8T” is The part where the period T (1T) is converted into the 7 / 8T period from the middle is different from the period T where the ejection timing is shifted by 1 / 8T of 1 dot or less at the beginning.
The conversion to the 7 / 8T cycle is performed based on the above-described misregistration information memory 18, and cannot be performed by the conventional technique shown in FIG.

  Next, FIG. 6 shows an ejection timing correction method of the (Y) color recording head with respect to the (K) color recording head in the carriage movement locus 104α shown in FIG. 13 (a). "The second stage is" (K) discharge timing 0 / 8T ", the third stage is" (Y) discharge cycle T is converted to 7 / 8T ", the fourth stage is" (Y) discharge timing relative to (K) " "Deviation".

  Further, in FIG. 6, the carriage movement locus (deflection) 104α is defined as a positive quadratic curve, and (Y) the color recording head ejection position with respect to the (K) color recording head ejection position at both ends of the carriage movement locus 104α. 1 dot image formation position shift at the position (image formation position) (1 dot on the left side of the (Y) color is (K) at the left end in the carriage movement locus 104α, and (Y) color is (K) at the right end. Assume that one dot) occurs on the right side of the color.

Further, in FIG. 6, in the process of image formation by the (K) color recording head and the (Y) color recording head during the movement of the carriage movement locus 104α, the number of ejection times of each color recording head: F1 to F17 (17 times). It is defined as
The “(K) discharge timing 0 / 8T” indicates a state where the discharge timing shift amount 0 (zero) after conversion to 8 times higher frequency in the “encoder signal”.

Next, “(Y) Discharge period T is converted to 7 / 8T” is that the period T in “(K) Discharge timing 0/8” is advanced to a period of 7 / 8T, and at this point, (K) F9 With the coincidence of the discharge timing and (Y) F9 discharge timing as the boundary (center), (Y) F1 with respect to (K) F1, (Y) F1 is shifted to the discharge timing side earlier by one dot (−8 / 8T), (K) F17 is (Y) F17, and (Y) F17 is shifted to the discharge timing side which is delayed by +1 dot (+ 8 / 8T), and (Y) F1 is (+ 8 / 8T) discharge timing correction and (Y ) F17 shows a state where (-8 / 8T) ejection timing correction is necessary. Needless to say, (Y) F2 to F8 and (Y) F10 to F16 require correction for the illustrated ejection timing deviation.
As described above, according to the present invention, in the discharge timing correction of one dot or less when the carriage having the recording head moves from the left to the right (main scanning direction), the fixed period T in the discharge timing is set to the value during the movement of the carriage. At the time of image formation, the ejection timing can be corrected by 1 dot or less by changing the ejection timing by a predetermined variable amount after conversion into the predetermined period T.

  In the above-described embodiment, the rotary encoder 15 in the moving mechanism 13 described above is equivalent to the combination of the above-described N-fold high-frequency generating circuit by combining the rotary encoder 15 capable of generating ejection timing in image formation of at least 2400 dpi. The effect is obtained.

Further, according to the first embodiment, the above-described misregistration information memory 18 is provided with the coordinates of the position where the image forming position deviates in the carriage movement locus 104α and the ejection timing correction amount as shown in FIG. By storing in advance and correcting at the image formation timing in the (C) color, (M) color, and (Y) color recording heads at the time of image formation, it is possible to correct the misalignment in the formation of the heavy color image.
In the above description, the above-described carriage movement locus (deflection) 104α is defined as a positive quadratic curve. However, the present invention is not limited to this, and can be applied to an arbitrary curve (curvature).

Next, a second embodiment of the image forming apparatus according to the present invention will be described.
The second embodiment of the present invention can be applied to a full-line image forming apparatus (second mechanism form) . Contact name in the description of the second embodiment are denoted by the same reference numerals the same components as the first embodiment described above, description thereof is omitted for the same advantages as the first embodiment To do . This second embodiment, for the first embodiment described above, as shown in FIG. 9, a plurality detector 19 is added to the configuration in place except for the positional deviation information Note Li 18.

  The plurality of detection units 19 are a plurality of sensors that detect the speed of the placement surface of the image forming material 31 on an endless belt on a platen described later on which the image forming material 31 is placed and conveyed.

 Next, an arrangement example of the image forming apparatus configured as described above in the second mechanism form (full line type image forming apparatus) will be described.

As shown in FIG. 7, the mechanism portion 46 of the full-line image forming apparatus has, for example, a color-compatible (K) larger than the width in the main scanning direction of the image forming material 31 conveyed from the upstream side in the conveying direction. Only a single recording head 24 having the head row divided into, for example, six head rows 24H ₁ ... 24H ₆ with a predetermined number of nozzles is disposed for the liquid ejection / ejection ports (nozzles) in color, or the recording head 24 The (C) color 50, (M) color 51, and (Y) color 52 recording heads having the same head row configuration are arranged on the carriage 49 arranged at predetermined intervals in the sub-scanning direction. The moving position information generating unit 15 having a rotary encoder is disposed on the rotation shaft of one roller 48a, and the motor is disposed on the rotation shaft of the other roller 48b. The moving mechanism driving unit 14 is disposed, and the rollers 48a and 48b are opposed to the conveying mechanism 13 that bridges the endless belt 16 of the moving body and places (moves) the image forming material 31 thereon. The arrangement is arranged.

  The image forming material 31 moves in the sub-scanning direction at each ejection timing when the (K) color 24, (C) color 50, (M) color 51, and (Y) color 52 are formed. It is determined by the number of pulses generated by the movement position information generation unit 15 using a detection signal of the edge sensor 47 that is (conveyed) and detects the edge of the tip as a trigger signal.

On the upstream side of the _six head rows 24H ₁ ... 24H _{6 in} the sub-scanning direction, at least 19S ₁ ... 19S ₆ in the plurality of detection units 19 are disposed substantially parallel to the _six head rows 24H ₁ . The image forming material 31 is moved (conveyed) in the sub-scanning direction, the edge sensor 47 detects the edge of the leading edge, and the average speed immediately before the image formation timing of the recording head 24 is sampled. The average speed fluctuation (reference (specification) speed in the transport mechanism 13: speed deviation with respect to β) in each width region of the _six head rows 24H ₁ ... 24H ₆ of the endless belt 16 in the moving body is calculated as 19S. ₁ ... 19S ₆ detects an image formation deviation factor in the main scanning direction.

For example, in the configuration in which only the recording head 24 is provided, each average speed of 19S ₁ ... 19S ₆ with respect to a reference (specification) speed: β in the transport mechanism 13 in a data table as shown in FIG. based on the speed deviation [Delta] [beta] ₁ ... [Delta] [beta] ₆ in, while calculating the head column _24H 1 ... 24H ₆ image forming position relative displacement amount Δx 1 _... Δx ₆ in the previous ejection data generating unit 17, via the aforementioned control unit 11 By transmitting to the timing generation unit 20, it is possible to correct the image formation position deviation of each of the head arrays 24H ₁ ... 24H ₆ in the recording head 24.

Further, for example, in the configuration in which the color recording heads of the (K) color 24, (C) color 50, (M) color 51, and (Y) color 52 are provided, the image forming position relative deviation amount Δx ₁ ... Δx ₆ The (C) color 50, (M) color 51, and (Y) color 52 color recording head arrays are superimposed on the (K) color recording head 24 having the head arrays 24H ₁ ... 24H ₆ to be corrected. The image is formed by correcting the ejection timing, or preferably, a data table as shown in FIG. 8B, that is, each color recording head of (C) color 50, (M) color 51, and (Y) color 52. The 19S ₁ ... 19S ₆ are equally arranged for the rows, and (C) CΔx ₁ ... CΔx ₆ in the (C) color recording head 50 for each head row 24H ₁ ... 24H ₆ in the (K) color recording head 24. , MΔx 1 _... MΔx ₆ in (M) color recording heads 51, Oyo (Y) ejection timing may be imaged by correcting to heavy color based on the image forming position relative displacement amount of YΔx 1 _... YΔx ₆ in the color recording head 52.

  As described above, according to the second embodiment, at least one recording head formed to be equal to or larger than the width in the main scanning direction of the image forming material conveyed from the upstream side in the conveying direction is divided into n by a predetermined number of nozzles. The n head arrays formed in this manner are independently controlled for ejection, and the same number of n detectors as the n head arrays are arranged substantially in parallel on the upstream side in the sub-scanning direction of the n head arrays, Image formation timing correction based on the speed fluctuation for each n head array in the moving body on which the forming material is placed can be performed.

Next, a third embodiment of the image forming apparatus according to the present invention will be described.
The third embodiment of the present invention can be applied to a serial type image forming apparatus (first mechanism form) and a full line type image forming apparatus (second mechanism form).

  In the description of the third embodiment, the same reference numerals are assigned to the same components as those in the first and second embodiments described above, and the same operations and effects as those in the first and second embodiments. The description is omitted.

The third embodiment, for the first embodiment described above, as shown in FIG. 10, Oh in alternative configurations in which the image device 26 and the mode setting unit 27 is added to excluding the positional displacement information memory 18 The

The mode setting unit 27 is a part of the operation panel of the image forming apparatus or another operation panel, and performs self-diagnosis and correction of the image forming position deviation in the image forming apparatus. This is a configuration with a mode function.
The image device 26 is configured by, for example, a scanner and image processing software, and the control unit 11 controls them.

  When the mode setting unit 27 executes the self-diagnosis mode for image formation position deviation, for example, (C) on a line formed with an image forming material by a (K) color recording head at a predetermined dot interval (C ) Only one color is formed with a heavy color image with one line, only (M) color is formed with one line with a heavy color image, and only (Y) color is formed with one line with a heavy color image.

  Next, the image forming material on which the heavy color image has been formed is read by a scanner in the image device 26, and (C) color, (M) color and (Y) are read by the image processing software installed in the control unit 11. Each color is extracted. In the control unit 11, an optimum threshold value for each color extraction is set in advance so as not to extract a portion overlapping with the (K) color. Further, the mode setting unit 27 is configured to be able to arbitrarily set or select a default value from γ in 1 / γ dot, which is a criterion for determining image formation position shift (overlapping color shift).

  Next, when the heavy color shift is completed, for example, a scale drawing of the image forming material is displayed on the operation panel in the mode setting unit 27, and the location of the heavy color shift is displayed on the scale drawing together with the value of the shift amount. The marking display or the number of occurrences of heavy color misregistration and the amount of heavy color misregistration are displayed, respectively, and a confirmation display as to whether or not to perform image forming position misalignment correction (heavy color misalignment correction) is displayed.

  When execution of image forming position deviation correction is selected, the coordinates of the position where the image forming position is shifted on the image forming material and the image forming position deviation amount at the coordinates are the data of the ejection information generation unit 17 described above. The image forming position deviation correction is performed based on the data table stored in the table and the next image formation.

  As described above, according to the third embodiment, the self-diagnosis mode for the image forming position shift is set by the operation of the operation panel in the mode setting unit 27, and the determination criterion for the image forming position shift (heavy color shift) is set. Can be arbitrarily set or selected from default values.

  Also, the scale of the image forming material is displayed on the operation panel, and the image formation position deviation (heavy color deviation) is displayed on the scale drawing together with the deviation amount value, or the occurrence of heavy color deviation The number and the amount of heavy color deviation are displayed, and a confirmation display as to whether or not to perform image formation position deviation correction (heavy color deviation correction) is displayed.

  Further, the coordinates of the position where the image forming position is shifted on the image forming material and the image forming position shift amount at the coordinates are stored in the data table of the ejection information generating unit 17 and are stored in the data table at the next image formation. Based on this, it is possible to perform image formation position deviation correction.

  Further, the present invention is not limited to the first embodiment, the second embodiment, and the third embodiment described above, and in the implementation stage, the constituent elements are modified without departing from the necessity. And can be materialized. For example, instead of the ejection data memory and the ejection timing circuit in the timing generation unit of the first embodiment and the second embodiment described above, all image formation data stored in the plane memory of the control unit is used as the information of the ejection information generation unit. This can also be realized by calling image formation data line by line on the basis of the image formation timing for each head row and forming an image with a drive circuit for each head row.

  Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the first embodiment, the second embodiment, and the third embodiment. For example, some components may be deleted from the overall components shown in the first embodiment, the second embodiment, and the third embodiment. Furthermore, you may combine the component covering different embodiment suitably.

1 is a diagram illustrating a conceptual configuration example in an embodiment of an image forming apparatus according to the present invention. 1 is a diagram for explaining a first embodiment of an image forming apparatus according to the present invention; FIG. FIG. 5 is a diagram for explaining an arrangement example of the serial type image forming apparatus (first mechanism form) in the first embodiment. It is a figure for demonstrating the data table of the serial type image forming apparatus (1st mechanism form) in 1st Embodiment. FIG. 10 is a diagram illustrating a comparison between a discharge timing correction timing chart in the prior art and a discharge timing correction timing chart of the image forming apparatus according to the present invention. FIG. 6 is a timing chart illustrating a (Y) head row ejection timing shift with respect to the (K) head row of the image forming apparatus according to the present invention. It is a figure for demonstrating the example of arrangement | positioning of the full line type image forming apparatus (2nd mechanism form) in 2nd Embodiment. It is a figure for demonstrating the data table of the full line type image forming apparatus (2nd mechanism form) in 2nd Embodiment. FIG. 6 is a diagram for explaining a second embodiment of the image forming apparatus according to the invention. FIG. 10 is a diagram for explaining a third embodiment of the image forming apparatus according to the invention. It is a figure which shows the example of 1 structure of the conventional serial type image forming apparatus. It is a figure which shows the example of 1 structure of the conventional full line type image forming apparatus. FIG. 10 is a diagram illustrating a change in carriage movement locus due to a deflection of a carriage support member in a conventional serial type image forming apparatus, and an image forming position shift in the main scanning direction of each recording head row.

Explanation of symbols

1,31 ... the image forming material, 1a ... an image forming material tip, 2 ... transport mechanism, 3,16 ... mobile, 4, _"6H 1 ... 6H _n", 50, 51, 52 ... print head, 5 , 49 ... Carriage, 7, 11 ... Control unit, 12 ... Plane memory, 13 ... Movement mechanism, 14 ... Movement mechanism drive unit, 15 ... Movement position information generation unit, 17 ... Discharge information generation unit, 18 ... Displacement information memory , 19 ... multiple detection units, 20 ... timing generation unit, "21M ₁ ... 21Mn" ... head row _{1 ... n} ejection data memory, "22D ₁ ... 21Dn" ... head row _{1 ... n} ejection timing circuit, "23D ₁ ... 23Dn "... head array _{1 ... n} driving circuit," _24H 1 ... 24Hn "... head array _{1 ...} n, 25 ... image formation data, 26 ... imaging equipment, 31a, 47 ... edge sensor, 32 ... mechanism of serial type image forming apparatus Part , 33a ... upper conveying roller, 33b ... lower conveying roller, 34a, 34b ... shaft, 35 ... pair of rollers, 36 ... moving mechanism, 37 ... motor, 38 ... rotary encoder, 39a, 39b ... fixing material, 40 ... supporting member 41, 42 ... pulley, 43 ... endless belt, 44a ... connecting portion, 45 ... mounting material, 46 ... mechanical part of full-line type image forming apparatus, 48a, 48b ... platen roller.

Claims (2)

An image forming unit that arranges a plurality of recording heads having nozzle rows formed by a plurality of ejection nozzles arranged along a main scanning direction orthogonal to a conveying direction of an image forming material in the conveying direction for each ink color; ,
An image forming material transport mechanism that is disposed opposite to the plurality of nozzle rows and holds and transports the image forming material;
A plurality of head arrays of each color obtained by dividing the nozzle array of each of the recording heads by a predetermined number of ejection nozzles are detected, and the transport speed of the image forming material transport mechanism is detected corresponding to each of the head arrays. A plurality of conveyance speed detectors,
Have
In a line type image forming apparatus for forming a heavy color image on the image forming material conveyed by the nozzle rows of the plurality of recording heads arranged in the conveying direction,
The control unit is configured to determine, based on the image formation position relative deviation amount of one head row, the image formation position relative deviation amount of each head row calculated based on the detection result of the conveyance speed from the plurality of conveyance speed detection units. An image forming apparatus comprising: a control unit that controls ink ejection timing so as to correct a heavy color shift of another head row.   The image forming apparatus according to claim 1, wherein the plurality of conveyance speed detection units are laser Doppler meters or ultrasonic Doppler meters.

Images