JP2009248348A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which is capable of preventing the occurrence of ink contamination due to floating and cockling of a paper, during passing through a line type recording head. <P>SOLUTION: A plurality of line type recording heads 51 and 52 each having an image forming range with a predetermined width are arranged in a zigzag pattern above a conveying surface 3, a first conveying roller 41 in the front step is arranged on the upstream side of the first line type recording head 51 in the front step and a second conveying roller 42 in the rear step is arranged outside the image forming range of the first line type recording head 51 in the front step. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus in which a plurality of line-type recording heads, for example, a plurality of ink-jet type line-type recording heads, are arranged in parallel to substantially increase the width of a recording area, and in particular, a technique for suppressing sheet lifting. It is related to.

Conventionally, in order to obtain a clear printing result in an inkjet image forming apparatus, for example, an inkjet printer, there are several problems.
One is the problem with paper. It is necessary to set the recording medium to be printed, generally the gap between the printing paper and the inkjet recording head, as narrow as possible.

However, when the printing paper absorbs moisture, it often causes a paper entrainment phenomenon, that is, a curling phenomenon due to a difference in moisture content between the front and back surfaces.
As an ink for an ink jet printer, an aqueous ink containing almost no oil component is mainly used. For this reason, when liquid ink is imprinted on the paper surface during printing, the ink moisture rapidly penetrates into the paper from the paper surface, and the curl phenomenon occurs rapidly. Or a phenomenon that the paper surface undulates, that is, cockling occurs.

  Therefore, in an ink jet printer, a clear print result can be obtained by performing printing while preventing the paper surface from being lifted from the paper transport surface to the ink jet recording head and keeping the space between the papers as narrow as possible.

  For this reason, in Patent Document 1, regardless of the state of the recording medium (cockling, curl, etc.), the recording medium is guided and supported at the position facing the recording head in order to prevent the recording medium from floating toward the recording head. An elastic member that holds the recording medium toward the platen is arranged upstream of the recording area, and the elastic member is elastically deformed according to the rigidity of the recording medium.

  Next, as a method of expanding the width of the recording area in an ink jet printer, a plurality of line-type recording heads are arranged in parallel to form a head unit, and the plurality of head units are arranged in multiple stages in the printing paper conveyance direction. In addition, there is a configuration in which the line type recording heads are arranged in a staggered manner.

However, in this configuration, the above-described problem, that is, the occurrence of paper floating and cockling becomes more remarkable.
For this reason, in Patent Document 2, in a line head type recording apparatus including a head unit composed of a plurality of recording heads, a position downstream of the recording head in the paper transport direction is used to prevent the recording medium from being bent. The bending prevention member is disposed so as to be rotatably supported by the rotation shaft, and the deflection prevention member is formed of a substantially polygonal thin plate member having a sharp apex.
JP 11-138923 A JP 2007-176002 A

  However, in the configuration of Patent Document 1, the position where the elastic member exerts the action on the printing paper that is the recording medium is only the paper introduction portion that is the most upstream position in the paper transport direction in the ink jet recording head, and the ink jet recording head The pressing action does not reach the paper that is passing through.

  Further, in the configuration of Patent Document 2, the deflection preventing member arranged to prevent the deflection of the recording medium is located on the downstream side of the recording head in the sheet conveying direction and immediately after printing. Since it abuts on the printing surface, there is a problem that smear due to ink occurs on the paper surface.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of preventing the occurrence of ink stains due to paper floating and cockling while passing through a line type recording head.

  In order to solve the above problems, an image forming apparatus according to the present invention includes a pair of upper and lower transport rollers that move a recording medium in a transport direction on a transport surface, and an image forming range having a predetermined width in a direction perpendicular to the transport direction. A plurality of line type recording heads arranged in a zigzag pattern above the conveying surface and arranged in parallel at a predetermined interval in a direction orthogonal to the conveying direction. The head row is formed, the recording head rows are arranged in multiple stages along the conveyance direction, the conveyance rollers are arranged in multiple stages along the conveyance direction, and the upstream conveyance roller is located upstream of the previous line type recording head. And the rear transport roller is disposed outside the image forming range of the front line type recording head.

Further, in the image forming apparatus of the present invention, the rear-stage transport roller is arranged between the front-stage printhead array and the rear-stage printhead array.
In the image forming apparatus of the present invention, the transport roller includes an upper transport roller and a lower transport roller that are paired up and down, and the rotational axis of the lower transport roller is more than the rotational shaft of the upper transport roller. It is located upstream in the transport direction.

  Further, in the image forming apparatus of the present invention, a regulating member that regulates the contact between the recording medium and the preceding line type recording head outside the image forming range of the preceding stage type recording head on the upstream side of the latter conveying roller, It is characterized in that it is arranged opposite to the conveying surface.

  In the image forming apparatus of the present invention, a paper introduction member having a predetermined width at least equal to that of the line type recording head in a direction orthogonal to the conveyance direction is opposed to the conveyance surface on the upstream side of the preceding line type recording head. It is characterized by having arranged.

  In the image forming apparatus according to the present invention, a suction conveyance unit that conveys the recording medium in the conveyance direction is provided downstream of the last line type recording head in the conveyance direction.

  In the image forming apparatus of the present invention, a point contact roller that makes point contact with the recording medium is provided downstream of the last line type recording head in the transport direction.

  As described above, according to the present invention, each line type recording head of the recording head array arranged in multiple stages along the recording medium conveyance direction forms an image on the recording medium in an image forming range of a predetermined width, thereby An image is formed at an arbitrary position on the medium.

  That is, the recording medium is conveyed between the preceding line type recording head and the conveying surface in a state in which lifting is prevented by the preceding conveying roller, and an image is formed on the recording medium by the preceding line type recording head. Further, the recording medium that has passed through the preceding line-type recording head is conveyed between the latter-stage line-type recording head and the conveying surface in a state that prevents the recording medium from being lifted by the latter-stage conveying roller. An image is formed on.

  At this time, since the line type recording heads are arranged in a staggered manner above the conveyance surface, the image forming range of the preceding line type recording head and the image forming range of the succeeding line type recording head do not overlap with each other. This conveyance roller can be disposed outside the image forming range of the preceding line type recording head.

  Therefore, it is possible to prevent the recording roller from coming up from the conveyance surface by contacting the recording medium without touching the image-formed area formed by the preceding line-type recording head.

  Therefore, even if the gap between the recording medium and the line type recording head is set narrow, the recording medium does not come into contact with the line type recording head, and a clear printing result can be obtained. Next, by disposing the rear-stage transport roller between the front-stage print head array and the rear-stage print head array, the transport direction in which the front-stage transport roller and the rear-stage transport roller separate the front-stage line-type print head. Prevents the recording medium from floating at the front and rear positions, and achieves a clear print result.

  Next, in the conveyance roller, the rotation axis of the lower conveyance roller is positioned upstream of the rotation axis of the upper conveyance roller in the conveyance direction, so that the recording medium is conveyed on the conveyance surface when passing through the conveyance roller. It is sent out obliquely downward. Accordingly, the recording medium passes between the line type recording head and the conveying surface while being urged in a direction away from the line type recording head, so that the gap between the recording medium and the line type recording head is between the sheets. Even if it is set narrowly, the recording medium does not come into contact with the line-type recording head, ink smear does not occur, and a clear printing result can be obtained.

  Next, a regulating member that regulates contact between the recording medium and the preceding line type recording head is disposed opposite the conveying surface outside the image forming range of the preceding line type recording head on the upstream side of the latter conveying roller. Thus, when the recording medium passes through the preceding line-type recording head, the regulating member prevents the recording medium from floating along the transport direction, so that there is a gap between the recording medium and the line-type recording head. The recording medium does not come into contact with the line-type recording head even if it is set narrowly, ink smear does not occur, and a clear printing result can be obtained.

  Next, on the upstream side of the previous line type recording head, by disposing a paper introduction member having a predetermined width at least equal to the line type recording head in a direction orthogonal to the conveying direction, facing the conveying surface, It is possible to suppress the occurrence of jam when the recording medium is introduced between the preceding line type recording head and the conveying surface.

  Next, by providing a suction conveying means for conveying the recording medium in the conveying direction downstream from the last line type recording head in the conveying direction, the image forming surface of the recording medium is contacted after forming the image. Without this, the recording medium can be transported by the suction transport means.

  Next, by providing a point contact roller that makes point contact with the recording medium downstream from the last line type recording head in the transport direction, the point contact with the image forming surface of the recording medium is performed after the image is formed. The recording medium can be conveyed in a state where the roller is in minimal contact.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, an ink jet printing apparatus will be described as an image forming apparatus.
1 to 5, an inkjet printing apparatus 1 includes a pair of upper and lower transport rollers 4 that move a printing sheet 2 that is a recording medium in a transport direction A on a transport surface 3, and a plurality of line-type recording heads 5. is doing. The line type recording head 5 has an image forming range having a predetermined width in a direction orthogonal to the conveying direction A, and a plurality of lines formed in a line shape as schematically and transparently shown in FIGS. The ink discharge portions 5a are arranged in a plurality of stages along the transport direction A, and may be of a type that discharges a plurality of colors in one ink discharge portion 5a. A single color is discharged in one ink discharge portion 5a. The ink discharge unit 5a may be of a type that discharges a different color, and the structure thereof is a known one, so that the description thereof is omitted.

  The conveyance surface 3 may be composed of a low friction member, may be coated with a low friction agent, or may be formed with a plurality of ribs along the conveyance direction A. A plurality of line-type recording heads 5 are arranged in a staggered manner above the conveyance surface 3, and a recording head array is formed by a plurality of line-type recording heads 5 arranged in parallel at a predetermined interval in a direction orthogonal to the conveyance direction A. The recording head arrays are arranged in multiple stages along the transport direction A, and the transport surface 3 is provided with openings 6 a at positions corresponding to the respective line-type recording heads 5.

  For this reason, in the direction orthogonal to the conveyance direction A, the image forming ranges of all the line type recording heads 5 do not overlap each other, and a plurality of line type recording heads 5 are arranged in parallel to substantially reduce the width of the recording area. An image forming apparatus with a widened area. In the present embodiment, two recording head arrays are arranged before and after the transport direction A, but the number of recording head arrays is not limited to the configuration exemplified in the present embodiment.

  In the following description, the line-type recording head 5 is described as a first line-type recording head 51 arranged in the preceding recording head row, and as the second line-type recording head 52 arranged in the following recording head row. The transport roller 4 will be described as a first transport roller 41 in the front stage, a second transport roller 42 in the rear stage, and a third transport roller 43 in the last stage.

  The transport rollers 4 are arranged in multiple stages along the transport direction A, the first transport rollers 41 are disposed on the upstream side of the first line type recording head 51 in the preceding stage, and the second line type recording head in the subsequent stage. A second transport roller 42 is disposed on the upstream side of 52, and a third transport roller 43 is disposed on the downstream side of the recording head row at the subsequent stage. The number of transport rollers 4 in the transport direction A is not limited to the configuration exemplified in this embodiment.

  The second transport roller 42 corresponds to a position outside the image forming range of the first line-type recording head 51 of the preceding stage, that is, between the adjacent first line-type recording heads 51, and the first stage of the preceding stage in the transport direction A. The line-type recording head 51 and the second line-type recording head 52 in the subsequent stage are disposed.

The third conveyance roller 43 corresponds to an area outside the image forming range of the second line type recording head 52 in the subsequent stage, that is, between the adjacent second line type recording heads 52.
As shown in FIG. 3, the 1st conveyance roller 41, the 2nd conveyance roller 42, and the 3rd conveyance roller 43 are arrange | positioned at the opening part 6b provided in the conveyance surface 3, and make a pair up and down, respectively. It consists of upper conveying rollers (driven rollers) 41a, 42a, 43a and lower conveying rollers (driving rollers) 41b, 42b, 43b. In the first transport roller 41 and the second transport roller 42, the rotational axis of the drive shaft 7 of the lower transport rollers 41b and 42b is transported in the transport direction more than the rotational axis of the driven shaft 8 of the upper transport rollers 41a and 42a. In A, it is located upstream. In the third conveyance roller 43, the rotation axis of the drive shaft 7 of the lower conveyance roller 43b is located downstream in the conveyance direction A with respect to the rotation axis of the driven shaft 8 of the upper conveyance roller 43a. The upper conveyance roller 43 a of the third conveyance roller 43 is a point contact roller that makes point contact with the printing paper 2.

  A regulating member 9 is disposed above the conveying surface 3 so as to face the conveying surface 3 and be spaced from the conveying surface 3 with a predetermined gap (for example, 2 mm). As shown in FIG. 3B, the regulating member 9 extends a predetermined distance upstream of the first line type recording head 51 in the conveying direction A, and the second line type recording head in the conveying direction A. It extends to the immediate upstream side of 52.

  The regulating member 9 is made of a conductive material, removes static electricity charged on the printing paper 2 to prevent the paper from sticking, and regulates the contact between the printing paper 2 and the first line type recording head 51 in the previous stage. The lower surface of the regulating member 9 protrudes downward by a predetermined distance (for example, 0.5 mm) from the lower surfaces of the first line type recording head 51 and the second line type recording head 52, and the lower conveying rollers 41b and 42b. Protrudes upward from the conveying surface 3 by a predetermined distance (for example, 0.8 mm).

  The regulating member 9 is located on the upstream side of the second line type recording head 52 at the rear stage, outside the image forming range of the first line type recording head 51 at the front stage, that is, between the adjacent first line type recording heads 51 adjacent to each other. Is located.

On the upstream side of the first line-type recording head 51 in the preceding stage, the paper introduction member 10 is disposed so as to face the conveyance surface 3 and with a predetermined gap (for example, 2 mm) between the conveyance surface 3. . As shown in FIG. 3A, the paper introduction member 10 extends from the immediate upstream side of the first line-type recording head 51 by a predetermined distance from the upstream side in the transport direction A.
The paper introduction member 10 has a predetermined width at least equal to that of the first line-type recording head 51 in a direction orthogonal to the transport direction A, and is disposed between the restriction member 9 and the restriction member 9. The paper introduction member 10 and the regulating member 9 have a shape in which the corner portion of the upstream end surface in the transport direction A is chamfered, and is wide open from the transport surface 3 so that the edge of the print paper 2 is released.

  Below the transport surface 3, the cap 11 faces the first line type recording head 51 and the second line type recording head 52 through the opening 6 a. The cap 11 is fitted to the first line type recording head 51 and the second line type recording head 52 during printing standby or the like and fulfills a moisture retaining function. The first, second and third transport rollers 41 are provided. , 42 and 43, the installation of the printing paper 2 is facilitated compared to the case where a belt is used to transport the printing paper 2.

  As shown in FIG. 4, it is possible to provide an auxiliary guide 12 on the upstream side of the second conveying roller 42. The auxiliary guide 12 moves the printing paper 2 between the upper conveying roller 42a and the lower conveying roller 42b. Toward the upper side from the transport surface 3.

  Further, as shown in FIG. 6, in place of the third conveyance roller 43, a suction conveyance belt device 13 that constitutes a suction conveyance means is disposed downstream in the conveyance direction A from the second line type recording head 52 at the subsequent stage. The suction conveyance belt device 13 attracts the printing paper 2 to the conveyance belt 14 by air suction and conveys it in the conveyance direction A.

With the above-described configuration, the present embodiment has the following operational effects.
The recording head rows are arranged in multiple stages along the conveyance direction A of the printing paper A, and the first line type recording head 51 and the second line type recording head 52 of each recording head row are within an image forming range having a predetermined width. By forming an image (printing) on the printing paper 2, an image can be formed at an arbitrary position on the printing paper 2.

  That is, the upper conveyance roller 41a and the lower conveyance roller 41b of the first conveyance roller 41 in the preceding stage are conveyed in the conveyance direction A in a state in which the printing paper 2 is pinched and prevented from being lifted, and the printing paper 2 is conveyed to the first conveyance roller 41b. The image is formed between the line type recording head 51 and the conveying surface 3 and an image is formed on the printing paper 2 by the first line type recording head 51.

  Further, the printing paper 2 that has passed through the first line-type recording head 51 is conveyed in the conveying direction A in a state where the upper conveying roller 42a and the lower conveying roller 42b of the second conveying roller 42 are pinched to prevent lifting. Then, the printing paper 2 is conveyed between the second line type recording head 52 and the conveying surface 3, and an image is formed on the printing paper 2 by the second line type recording head 52.

  At this time, since the line type recording heads 5 are arranged in a staggered manner above the conveying surface 3, the image forming range of the first line type recording head 51 at the front stage and the second line type recording head 52 at the rear stage. The second image forming range does not overlap, and the second transport roller 42 at the rear stage can be disposed outside the image forming range of the first line type recording head 51 at the first stage.

  Therefore, the second conveyance roller 42 at the rear stage abuts on the printing paper 2 without touching the image-formed area formed by the first line-type recording head 51 at the front stage, and the printing paper 2 is moved from above the conveyance surface 3. Can prevent floating.

  Further, by disposing the second transport roller 42 at the rear stage between the recording head row at the front stage and the recording head row at the rear stage, the first transport roller 41 at the front stage and the second transport roller 42 at the rear stage are arranged. The printing paper 2 is prevented from floating at the front and rear positions in the transport direction A across the first line type recording head 51 at the preceding stage.

  Therefore, even if the gap between the printing paper 2 and the first and second line type recording heads 51 and 52 is set narrow, the printing paper 2 becomes the first and second line type recording heads 51 and 52. A clear print result can be obtained without contact.

  Next, in the first and second transport rollers 41 and 42, the rotational axis of the lower transport rollers 41b and 42b is positioned upstream in the transport direction A with respect to the rotational shaft of the upper transport rollers 41a and 42a. Thus, when passing through the transport rollers 41 and 42, the printing paper 2 is sent obliquely downward toward the transport surface 3. That is, the printing paper 2 is corrected so as to curl downward.

  Therefore, the printing paper 2 is urged in the direction away from the first and second line type recording heads 51 and 52, while the first and second line type recording heads 51 and 52 and the conveyance surface 3 are between them. Pass through. Further, when the printing paper 2 passes through the first line-type recording head 51 in the preceding stage, the regulating member 9 prevents the printing paper 2 from floating along the transport direction A. By correcting the conveyance rollers 41 and 42 so that the printing paper 2 is curled downward, the printing paper 2 is prevented from floating in the region along the second line-type recording head 52 in the conveyance direction A. There is no need to arrange a regulating member.

  Therefore, even if the gap between the printing paper 2 and the first and second line type recording heads 51 and 52 is set narrow, the printing paper 2 becomes the first and second line type recording heads 51 and 52. There is no contact, ink smear does not occur, and a clear print result can be obtained.

Further, the paper introduction member 10 suppresses the occurrence of a jam when the printing paper 2 is introduced between the first line type recording head 51 and the transport surface 3 in the previous stage.
Next, the upper conveying roller 43a of the third conveying roller 43 forms a point contact roller, so that after the image is formed, the printing paper 2 is brought into minimal contact with the image forming surface of the printing paper 2. Can be transported.

  Further, in the case where the suction conveyance belt device 13 is disposed instead of the third conveyance roller 43, the print paper 2 is sucked by air suction without contacting the image forming surface of the print paper 2 after the image is formed. It can be attracted to the transport belt 14 and transported in the transport direction A.

The top view which shows the structure of the inkjet printing apparatus in embodiment of this invention Plan view showing the configuration of the inkjet printing apparatus 2 shows a configuration of the inkjet printing apparatus, wherein (a) is a cross-sectional view taken along the line AA in FIG. 2, and (b) is a cross-sectional view taken along the line BB in FIG. Side view showing an auxiliary guide in the inkjet printing apparatus A perspective view showing the ink jet printing apparatus Side view showing another configuration of the inkjet printing apparatus

Explanation of symbols

A Conveying direction 1 Inkjet printing apparatus 2 Printing paper 3 Conveying surface 4 Conveying roller 5 Line type recording head 5a Ink ejection part 6a, 6b Opening 7 Drive shaft 8 Driven shaft 9 Restricting member 10 Paper introducing member 11 Cap 12 Auxiliary guide 13 Suction Conveying belt device 14 Conveying belt 41 First conveying roller 42 Second conveying roller 43 Third conveying roller 41a, 42a, 43a Upper conveying roller (driven roller)
41b, 42b, 43b Lower conveyance roller (drive roller)
51 First line type recording head 52 Second line type recording head

Claims (7)

A pair of upper and lower transport rollers for moving the recording medium on the transport surface in the transport direction, and a line type recording head having an image forming range of a predetermined width in a direction orthogonal to the transport direction,
A plurality of line-type recording heads are arranged in a zigzag pattern above the conveying surface, and a plurality of line-type recording heads arranged in parallel at a predetermined interval in a direction orthogonal to the conveying direction form a recording head row. Are arranged in multiple stages along the conveying direction,
Conveying rollers are arranged in multiple stages along the conveying direction, the preceding conveying roller is arranged upstream of the preceding line type recording head, and the succeeding conveying roller is arranged outside the image forming range of the preceding line type recording head. An image forming apparatus.   The image forming apparatus according to claim 1, wherein the rear-stage transport roller is disposed between the front-stage printhead array and the rear-stage printhead array.   The transport roller is composed of an upper transport roller and a lower transport roller that are paired up and down, and the rotational axis of the lower transport roller is positioned upstream of the rotational axis of the upper transport roller in the transport direction. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   That the regulating member that restricts the contact between the recording medium and the preceding line type recording head is disposed opposite the conveying surface outside the image forming range of the preceding line type recording head on the upstream side of the latter conveying roller. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   A sheet introducing member having a predetermined width at least equal to that of the line type recording head in a direction orthogonal to the conveying direction is disposed on the upstream side of the preceding line type recording head so as to face the conveying surface. Item 5. The image forming apparatus according to any one of Items 1 to 4.   The image according to claim 1, further comprising a suction conveyance unit that conveys the recording medium in the conveyance direction downstream from the last line type recording head in the conveyance direction. Forming equipment.   The image forming apparatus according to claim 1, further comprising a point contact roller that makes point contact with a recording medium downstream from the last line type recording head in the transport direction.

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