JP2003094742A - Inkjet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet printer capable of preventing a paper from being stained when the paper on which cockling or bending occurs is brought into contact with a recording head. SOLUTION: A plurality of platen ribs 44 are provided to a top face of a platen 43 in the inkjet printer 1 such that the platen ribs 44 are provided in parallel to a conveyance direction of a paper X at a predetermined distance. A paper discharge roller 54 and a paper guide 51 are provided to a portion at a downstream side of the platen 43. The paper discharge roller 54 is provided between extension lines extended from the platen ribs 44 in the conveyance direction of the paper X and the paper X is urged from the upper side. A paper discharge rib 52 protruding toward the paper X is provided to a position corresponding to an extension line of the platen rib in the lower end section of the paper discharge guide 51.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet printer.

[0002]

2. Description of the Related Art In an ink jet printer, for example, a platen is arranged diagonally below and opposite to a head for printing by ejecting ink, and a printing paper (recording medium) is carried on the upper surface of the platen. The printing is performed by the head in the state of being placed on. Then, for example, a transport roller for transporting the paper is disposed on the upstream side of the platen in the transport direction of the paper, and a discharge roller and a discharge roller for guiding the printed and transported paper are provided on the downstream side of the platen. A guide is provided.

When an image such as a photograph is printed on a sheet in an ink jet printer, the ink is applied in a state where a portion corresponding to the image is filled. Therefore, when an image is printed on almost the entire size of the paper, the ink is applied so as to fill the entire area of the paper. Further, when a gradation is expressed using light color ink, a large amount of ink is applied to the paper to express a dark color.

For this reason, paper coated with a large area of ink or coated with a large amount of ink spreads when the ink soaks into the paper, which is called cockling. I'll be sick. In addition, when the paper is impregnated with a relatively large amount of ink, the paper is stretched and its own weight is heavy, and the paper is easily bent.

[0005]

In the ink jet printer as described above, the cockled or folded paper is rubbed against the recording head when it is conveyed, so that the paper is not contaminated with ink or the like. It may adhere. In particular, when the cockling-generated paper passes through the platen, the two adjacent ridges of the cockling become one large ridge, and the ridges spill over to the upstream side in the paper conveyance direction. There is a problem that it is easy to contact the recording head.

Further, when plain paper, which is easier to absorb ink than glossy paper or the like, is used, the above problem becomes remarkable.

It is an object of the present invention to prevent cockling or breakage of a sheet-shaped recording medium during printing, and prevent the recording medium from coming into contact with the recording head and causing dirt to adhere to the recording medium. It is to provide an inkjet printer that can do the above.

[0008]

The invention according to claim 1 is
A conveying unit that conveys a sheet-shaped recording medium, a head that ejects ink onto the recording medium that is conveyed by the conveying unit to print, and a recording medium that is printed by the head are supported from the back side. An inkjet printer provided with a platen disposed so as to face the head, wherein the platen has a plurality of protrusions extending in the transport direction of the recording medium by the transport unit and protruding toward the head side. And an embedded portion having an upper surface that does not project to the head side with respect to the upper portion of the platen ribs, at least on the upstream side in the transport direction between the plurality of platen ribs.

According to the ink jet printer of the first aspect, the sheet-shaped recording medium being printed by the head is supported from the back side at the position of the platen rib provided on the platen when the back side is supported by the platen. In this state, a gap is formed between the platen ribs between the recording medium and the platen, but when the printed recording medium absorbs ink and extends, the recording medium enters the gap. become. As a result, a wave (that is, a cockling) generated when the recording medium absorbs ink and expands is guided so as to have peaks at the platen ribs and valleys between the platen ribs.

Therefore, based on the period in which the platen ribs are formed, the period and amplitude of peaks and troughs when cockling (wave) occurs in the recording medium (amplitude is affected by the period).
Can be adjusted to be substantially constant, so that a wave having a large amplitude such that the recording medium comes into contact with the head is prevented from occurring, and the period of the wave generated in the recording medium is disturbed to increase the amplitude. It is possible to avoid rubbing between the head and the head.

Further, when the platen rib is simply provided on the platen, in printing by the head, the recording medium supported from the back side of the platen is slightly wavy due to the platen rib before cockling occurs.
If the distance from the head to the recording medium changes slightly depending on the location, there is a possibility that the ink landing position may be displaced, which may affect print quality such as uneven density. Therefore,
By providing a filling portion having an upper surface that does not project to the head side with respect to the upper portion of the platen ribs between the platen ribs, it is possible to suppress the waviness of the recording medium by the platen ribs, and between the head and the recording medium. Since the distance is almost constant, it is possible to suppress the influence of providing the platen rib and to secure good printing quality.

When the upper surface of the filling portion is formed so as to completely fill the space between the platen ribs,
Since the effect of regulating the period and amplitude of the cockling wave by the platen rib is weakened, the platen upstream of the recording medium in the transport direction, that is, the portion where the ink ejected from the head does not soak into the recording medium At the downstream side of the platen in the conveyance direction of the recording medium, that is, at the portion where ink begins to seep and the recording medium begins to expand, the embedded portion is formed It is preferable that the height between the platen ribs is reduced without forming the groove to maintain the effect of regulating the cycle of the cockling wave of the recording medium by the platen ribs.

According to a second aspect of the present invention, there is provided a conveying means for conveying a sheet-shaped recording medium, a head for ejecting ink onto the recording medium conveyed by the conveying means for printing, and a print for printing by the head. An inkjet printer provided with a platen arranged so as to face the head so as to support a recording medium to be performed from the back side, wherein the platen has a recording medium along a conveyance direction of the recording medium by the conveying means. Between a plurality of platen ribs extending and protruding toward the head side, and between the plurality of platen ribs,
An embedding portion that is provided with a space from the platen rib, has an upper surface that does not project to the head side with respect to the upper portion of the platen rib, and has a notch that widens toward the downstream side in the transport direction. It is an inkjet printer characterized by having.

According to the ink jet printer of the second aspect, since the notch is formed on the downstream side of the filling portion in the conveying direction, the notch is widened toward the downstream side. Therefore, the ink is sucked on the downstream side of the filling portion. When the expanded recording medium enters the notch, the cockling is formed in the recording medium in a state in which the period is regulated by the platen rib, as in the case where the filling portion is not provided. Therefore, it is possible to make the period and the amplitude of the wave generated on the recording medium that has been absorbed by the ink during printing and extended substantially constant.
As a result, rubbing between the recording medium and the head can be avoided, and good print quality can be ensured. That is, if the valley portion of the recording medium is pushed up in the filling portion and the wave of the paper is made too gentle, the extended amount of the recording medium absorbed by the ink cannot be escaped, but the recording medium is further extended. By providing a notch on the downstream side of the filling section of the platen that is in a state that expands toward the downstream side in response to the expansion of the paper, the valley portion of the paper is deepened and the expansion of the paper is released. it can. Accordingly, it is possible to reliably cause the paper to undergo cockling in which peaks and valleys are repeated at a predetermined cycle while suppressing the influence of the platen rib on the printing quality. It should be noted that the notch provided in the filling portion is not only the fact that the filling portion is not provided at the notch portion on the platen, and that the notch portion has a filling portion lower than the upper surface of the filling portion. Alternatively, the notch may be a recess that is deeper than the bottom surface of the platen.

According to a third aspect of the present invention, there is provided a transporting means for transporting the sheet-shaped recording medium, and a head for ejecting ink onto the recording medium transported by the transporting means for printing.
An inkjet printer provided with a platen arranged so as to face the head so as to support a recording medium on which printing is performed from the back side from the back side. Between a plurality of pairs of grooves extending in parallel with each other along the transport direction and between the grooves of the pair of grooves, the width widens toward the downstream side in the transport direction. An ink jet printer having a recess.

According to the ink jet printer of the third aspect, the portion between the grooves of the pair of grooves provided on the platen has the same function as the filling section of the second aspect, and the two grooves are provided. The pair has a function similar to that of the platen rib of the second aspect, and the recess has a function similar to that of the notch of the second aspect, and the same effect as the second aspect can be obtained.

The invention according to claim 4 is the invention according to claim 1 or 2.
In the inkjet printer described above, a discharge roller and a discharge guide are provided on the downstream side of the platen in the transport direction, and the discharge roller is in a region extending between the plurality of platen ribs in the transport direction. The paper ejection guide is provided so as to come into contact with the printing surface of the recording medium, and the paper ejection guide is a region corresponding to a position where the platen rib is extended in the transport direction and protrudes so as to guide the recording medium from the back side. It is an inkjet printer characterized by having.

According to the ink jet printer of the fourth aspect, the same effect as that of the ink jet printer of the first aspect or the second aspect can be obtained, and at the position of the platen, the period of peaks and valleys on the recording medium is formed by the platen ribs or the recesses. And cockling occurs in a state in which the amplitude is adjusted to be substantially constant, and when the leading side of the recording medium reaches the discharge roller, it is within a region extending between the platen ribs in the transport direction, that is, At the portion corresponding to the valley of the cockling arranged by the platen rib, the printing surface side of the recording medium is pressed from above by the paper discharge roller.

Further, a plurality of paper discharge ribs provided in a region corresponding to a position where the platen rib of the paper discharge guide is extended in the carrying direction and projecting so as to guide the recording medium from the rear side are provided. The part that becomes the mountain of the cock ring is supported from the back side. By these paper discharge rollers and paper discharge ribs, the peaks and valleys of the cockling of the recording medium passing through the platen are held. Then, in the recording medium in a state where it is arranged from the platen to the part of the paper discharge roller and the paper discharge guide, the peaks and valleys of the cock ring arranged by the platen rib are maintained from the platen to the paper discharge roller and the paper discharge guide. As a result of this, it is ensured that adjacent peaks on the downstream side of the platen will stick to each other and the amplitude will increase, and this will spread to the upstream side of the recording medium, causing the recording medium to contact the head. It can be prevented. In addition, the plurality of peaks and troughs from the platen to the paper ejection roller and the paper ejection guide are held in the recording medium, so that the recording medium is reinforced by the peaks and troughs, and the recording medium is folded. Can be prevented. In addition, in the area corresponding to the position where the platen rib is extended in the transport direction, the paper discharge rib protruding so as to guide the recording medium from the back side is, of course, the width of the paper discharge rib (in the direction orthogonal to the transport direction). (Length) is not the same as the width of the platen rib. It is particularly preferable that the width of the paper discharge rib is substantially the same as the width of the platen rib, but it may be smaller than the width of the platen rib or may be appropriately large, and it is preferably about twice or less the width of the platen rib.

According to a fifth aspect of the present invention, there is provided a conveying means for conveying a sheet-shaped recording medium, a head for ejecting ink onto the recording medium conveyed by the conveying means for printing, and printing by the head. An inkjet printer comprising a platen arranged so as to face the head so as to support the recording medium to be performed from the back side, wherein the platen extends along the conveyance direction of the recording medium by the conveying means. A plurality of platen ribs that are present and project toward the head are provided, and a discharge guide unit that guides the recording medium substantially along the transport direction is provided downstream of the platen in the transport direction. A first guide member provided so as to come into contact with the printing surface of the recording medium in a region extending between the plurality of platen ribs in the transport direction, Ratenribu in an area corresponding to a position extending in the conveying direction, an ink jet printer, characterized in that it comprises a second guide member which projects so as to guide the recording medium from the back side.

According to the ink jet printer of the fifth aspect, the period and amplitude of the peaks and troughs of the cockling generated on the recording medium are adjusted to be constant by the platen rib. Further, on the downstream side of the platen, discharge guide means for guiding the recording medium that has been printed and carried out is provided, and the discharge guide means is provided with a first guide member and a second guide member.

The first guide member has a region extending between the plurality of platen ribs in the carrying direction, that is,
The second guide member is arranged in the valley portion of the cock ring arranged by the platen ribs of the recording medium, and the second guide member is a region corresponding to the position where the platen ribs are extended in the transport direction, that is, the cock arranged by the platen ribs of the recording medium. It is placed in the mountain part of the ring. Then, on the downstream side of the platen, the first guide member presses the valley portion of the recording medium from above and the second guide member supports the mountain portion of the recording medium from below, and the platen rib is provided on the downstream side of the platen. It is possible to maintain the peaks and valleys of the cockling arranged by the above.

Thus, it is possible to prevent a situation in which adjacent peaks are stuck to each other on the downstream side of the platen and the amplitude is increased, which ripples to the upstream side of the recording medium and the recording medium comes into contact with the head. Further, since the plurality of peaks and troughs are maintained up to the downstream side of the platen, the recording medium is in a state of being reinforced by the peaks and troughs, so that the recording medium can be prevented from being broken.

According to a sixth aspect of the present invention, there is provided a conveying means for conveying a sheet-shaped recording medium, a head for ejecting ink onto the recording medium conveyed by the conveying means for printing, and printing by the head. An inkjet printer comprising a platen arranged so as to face the head so as to support the recording medium to be performed from the back side, wherein the platen extends along the conveyance direction of the recording medium by the conveying means. A plurality of platen ribs that are present and protrude toward the head side are provided, and a paper discharge roller and a paper discharge guide are provided on the downstream side of the platen in the transport direction, and the paper discharge roller is provided between the plurality of platen ribs. Is provided so as to come into contact with the printing surface of the recording medium in a region extended in the transport direction, and the paper ejection guide extends the platen rib in the transport direction. In the region corresponding to the position, an ink jet printer characterized by comprising a projecting sheet discharge ribs to guide the recording medium from the back side.

According to the ink jet printer of the sixth aspect, the paper discharge roller corresponds to the first guide member of the fifth aspect,
The discharge rib corresponds to the second guide member of claim 6, and
The same operational effect as can be obtained.

The invention according to claim 7 is the invention according to claim 4 or 6.
In the inkjet printer according to the description, an end paper discharge roller is provided on the downstream side of the platen in the transport direction so as to come into contact with a side edge portion of a print surface of a recording medium, and the end paper discharge roller is An inkjet printer having a diameter larger than that of a paper discharge roller.

According to the invention described in claim 7, the same action and effect as in claim 4 or 6 can be obtained, and the end portion discharge roller discharges the side edge portion of the recording medium on the downstream side of the platen. When it is pushed deeper than the rollers and the side edge of the recording medium that has been soaked with ink curls and rises,
This can be suppressed, and the side edge of the recording medium can be prevented from coming into contact with the head and rubbing. Further, if the diameter of the paper ejection roller is increased, the load on the conveyed recording medium is increased. However, since the diameter of the end paper ejection roller corresponding to the side edge of the recording medium is increased, the paper ejection property of the recording medium is increased. It is possible to prevent the side edges of the recording medium from being lifted up due to curling without decreasing the value.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments to which the present invention is applied will be described below in detail with reference to the drawings. In the present embodiment, an example in which the inkjet printer of the present invention is applied to a large-format inkjet printer will be described. However, the present invention can be applied to various inkjet printers and may include an inkjet printer mechanism. For example, the present invention can be applied to a copying machine, a facsimile, and other devices having a built-in printer mechanism.

FIG. 1 is a cross-sectional view of an ink jet printer 1 according to this embodiment as seen from the lateral direction. As shown in the figure, the ink jet printer is covered with a case 2 on the outer side, and inside the case 2, a paper feed section 3 is provided at an upper portion thereof, and a print section 4 is provided below the paper feed section 3. A paper discharge unit 5 is arranged below the printing unit 4. Then, a sheet conveying path extending from the sheet feeding section 3 to the sheet discharging section 5 via the printing section 4 is formed in a substantially straight state obliquely from the back side of the upper portion to the front side of the lower portion in the case 2. .

FIG. 2 is an enlarged view of the peripheral portion of the printing unit 4 of the ink jet printer 1 according to this embodiment. The paper feed unit 3 includes a spindle 31 (shown in FIG. 1), a paper feed guide 32, a conveyance roller 33a and a pressing roller 33b.
It has and.

A roll-shaped sheet X (recording medium) is detachably attached to the sheet feeding section 3 by a spindle 31. Further, the transport roller 33 a and the pressing roller 33 b are arranged on the upstream side of the recording head 42. The paper feed guide 32 guides the conveyance of the paper X from the spindle 31 to the printing unit 4 along the paper conveyance path.

The transport roller 33a and the pressing roller 33b are
The sheet X is conveyed to the printing unit 4, and the pressing roller 33b presses the sheet X against the conveyance roller 33a that is rotationally driven to convey the sheet. Further, the transport roller 33a and the pressing roller 33b are arranged so as to feed the paper along the paper transport path. In this embodiment, a roll-shaped sheet is used as the sheet X, but a cut sheet-shaped sheet may be used.

The printing unit 4 comprises an ink jet type recording head 42, a carriage 41 equipped with the recording head 42 and moving, and a platen 43 arranged so as to face the recording head 42.

Ink such as cyan (C), magenta (M), yellow (Y), and black (K) is supplied to the recording head 42 by a tube or an ink cartridge (not shown). The carriage 41 is configured to move in the main scanning direction which is a direction perpendicular to the paper conveyance direction (sub scanning direction).

Then, with the back surface of the paper X supported on the upper surface 43a of the platen 43 facing the recording head 42, the recording head 42 moves the paper X on the platen 43.
Ink is ejected on. Therefore, the printing surface is the upper surface side of the paper X that is obliquely conveyed along the paper conveyance path.
Printing is performed with the back surface of the paper X opposite to the printing surface supported by the platen 43. A suction chamber (not shown) is provided on the back side of the platen 43, and a suction port (not shown) made up of a plurality of small holes communicating with the suction chamber is provided so that the recording head 42 can perform printing. The sheet X is held by suction on the sheet transport surface.

As shown in FIG. 3, on the upper surface 43a of the platen 43 facing the recording head 42, a plurality of platen ribs 44, which are ridges extending parallel to the transport direction of the paper X, are provided. That is, the platen rib 44 projects from the upper surface 43 a of the platen 43 toward the back surface of the paper X on the platen 43, and
It has a long shape along the transport direction. Further, the platen ribs 44 are arranged at equal intervals in the direction orthogonal to the transport direction of the paper X. Further, the spacing between the platen ribs 44 is set so that the cockling of the paper X on the platen 43 occurs as described later.
The cycle of the wave peaks due to the cockling of the paper sheet X is the cycle desired in advance. That is, when the platen ribs 44 are provided on the upper surface 43a of the platen 43 along the transport direction of the paper X, the platen ribs 44 have the above-mentioned peaks and the spaces between the platen ribs 44 have the above-mentioned valleys. Cockling occurs at X.

Here, if the space between the platen ribs 44 is made large to some extent, the cycle in which the peaks and valleys repeat becomes long, and the amplitude also increases correspondingly to the cycle and the peaks become high. The shorter, the shorter the period and the smaller the amplitude.
If the spacing between the platen ribs 44 is too large or too small, the peaks and the platen ribs 44 do not always have a one-to-one correspondence. From the above, if the spacing between the platen ribs 44 is set to be a certain spacing, the peak portion due to cockling can be lowered, and even if cockling occurs, the portion where the paper becomes a peak becomes the recording head 42.
It is possible to prevent contact with. Although the optimum spacing between the platen ribs 44 is influenced by the type of recording medium such as the paper X, the optimum spacing can be experimentally determined.

The paper discharge section 5 mainly includes a paper discharge guide 51.
And a disk-shaped paper discharge roller 54 and an end paper discharge roller 55 provided on the rotary shaft 53.

The rotary shaft 53 is rotatably supported by a bearing portion (not shown) at a position downstream of the recording head 42 and the platen 43 in the transport direction of the paper X. Also,
The rotation axis is arranged in a direction orthogonal to the paper X conveyance direction, and is arranged slightly above the paper conveyance path.

Then, as shown in FIG.
Is provided with a paper discharge roller 54 that guides the paper X so that it does not float up, and an end paper discharge roller 55 that guides the side edge of the paper X so that it does not curl up and float. The paper discharge roller 54 is arranged in a region where a portion between the platen ribs 44 is extended along the transport direction, and more specifically, is located at a position where the extension lines of the platen ribs along the transport direction are substantially bisected. It is arranged. Further, the edge portion discharge rollers 55 are arranged at positions corresponding to the left and right side edge portions of the sheet X, respectively. Further, the paper discharge rollers 54 and the end paper discharge rollers 55 are arranged so that the outer peripheral portions thereof overlap the paper transport path, and are configured to come into contact with the transported paper X and rotate. Further, the paper discharge roller 54 and the end paper discharge roller 55 are coaxially arranged, for example, with the rotation center of the rotation shaft 53 as the rotation center, and the paper discharge roller 54
The diameter of the end portion discharge roller 55 is larger than that of the end discharge roller 55.

The paper discharge guide 51 is provided on the downstream side of the platen 43, below the paper transport path, so as to guide the paper X from the back side, and the paper discharge roller 5 is provided.
4 and the portion corresponding to the edge discharge roller 55 are the discharge rollers 5
4 and the end portion discharge rollers 55 are in a recessed state so as not to interfere with them. Then, the paper discharge guide 51 is arranged up to the vicinity of the carry-out port for discharging the paper X of the case 2, and a plurality of paper discharge ribs 52 are provided at the end portion on the end side of the paper discharge guide 51.

The discharge rib 52 is, for example, the discharge guide 51.
Is formed by bending the downstream end of the. Further, the paper discharge ribs 52 are provided in the regions corresponding to the positions of the platen ribs 44 extended in the carrying direction. In addition, the discharge rib 52 does not depend on the bending process,
It may be formed by thickening the downstream end of the paper ejection guide or by attaching another member.

The operation from the time the paper X is supplied / printed to the printing unit 4 to the time the paper is ejected will be described below. The roll-shaped paper X is set on the spindle 31, and the leading end of the paper is guided along the paper feed guide 32 to the conveying roller 33a and the pressing roller 33b to align the leading end of the paper.

The sheet X is conveyed while being sandwiched between the conveying roller 33a and the pressing roller 33b, and reaches the printing unit 4.
In the printing unit 4, the recording head 42 prints the paper X while the paper X is supported by the platen 43. At this time, in the upstream side portion of the upper surface 43 a of the platen 43, the paper X is not in a state of absorbing a large amount of ink and extending, and the paper X is supported by the platen ribs 44 from the back surface side and the platen ribs 44 A space is provided between the sheet X and the upper surface 43a of the platen 43 between them. It should be noted that the upstream portion of the platen 43 is a portion corresponding to a portion above a substantially central portion of an attachment position where ink is attached by the recording head 42 of the paper X supported by the platen 43, and the platen 43. The downstream side portion of is a portion below the upstream side portion.

In the downstream portion of the platen 43, for example, when an image is printed so as to fill the printing surface of the paper X, the paper X absorbs ink and extends toward the downstream side. Therefore, between the platen ribs 44, there is no platen rib 44 that supports the back surface of the paper X, and therefore the paper X approaches the upper surface 43a of the platen 43 in accordance with the expansion of the paper X. Further, since the platen 43 is adapted to suck the paper X as described above, when the paper X approaches the upper surface 43a of the platen 43, the paper X is sucked from the back surface side, and between the platen ribs 44. , Paper X is platen 4
3 is in contact with the upper surface 43a. From the above, the sheet X is in a state in which the portion supported by the platen ribs 44 is a mountain on the downstream side of the platen 43 and the wave between the platen ribs 44 is a valley. That is,
Due to the platen ribs 44 and suction, the paper X is almost forcibly cocked, and the platen ribs 4
The peaks and troughs of the cockling are formed in a cycle based on the interval between the four, and the amplitude of the peaks and valleys is also regulated by the above cycle.

That is, the cycle and the amplitude of the cockling generated on the paper X can be adjusted to be substantially constant, and the predetermined cockling can be reliably formed. Therefore, it is possible to prevent cockling with a large amplitude from occurring on the paper X, and to avoid rubbing between the paper X and the recording head 42 due to the disturbance of the cycle of the cockling occurring on the paper X to increase the amplitude. Therefore, good printing quality can be secured.

Subsequently, the paper X delivered onto the paper ejection guide 51 is pressed by the paper ejection roller 54 so as not to float up. At this time, the paper ejection roller 54
Is a platen rib 44 on the downstream side of the platen 43.
Since it is provided substantially at the center between the extension lines of the sheet X along the conveyance direction, the valley portion of the cockling generated on the sheet X is pressed as described above. As a result, even on the downstream side of the platen 43, the above-mentioned peaks and troughs of the cockling of the sheet X are maintained. Therefore, even on the downstream side of the platen 43, the cycle and amplitude of the cockling generated on the paper X can be adjusted to be substantially constant. In addition, at the position corresponding to the paper discharge roller 54, both side edges of the paper X are fed by the end paper discharge rollers 55 provided at the positions corresponding to the side edge portions of the paper X.
It is pressed from the printing surface side (upper side). As a result, when the side edge of the paper X in which the ink is soaked is about to curl, it can be pressed down. Further, the end paper discharge rollers 55 are arranged coaxially with the paper discharge rollers 54 (the distance between the rotation center of the end paper discharge rollers 55 and the paper X is the rotation center of the paper discharge rollers 54 and the paper X). The diameter of the end discharge roller 55 is larger than the diameter of the discharge roller 54. Therefore, the end discharge roller 55 is located on the side of the paper X. It is possible to prevent the curl of the paper X by pressing the edge portion further downward. Also,
Increase the diameter of the paper discharge roller 54 and the end paper discharge roller 55,
If the paper X is configured to be pressed downward significantly, the load of moving the paper X in the transport direction will be heavy, but by increasing only the diameter of the end paper discharge roller 55, it is possible to prevent the paper X from moving. It is possible to ensure a smooth movement of the paper X with the increase of the load being minimized.

Then, the sheet passes over the sheet ejection guide 51 and is ejected to the outside of the case 2. Here, since the sheet discharge ribs 52 are provided at the ends of the sheet discharge guide 51 on the sheet discharge side at the positions corresponding to the extension lines of the platen ribs 44 along the transport direction of the sheet X, respectively. The mountain portion of the cock ring corresponding to the platen rib 44 is supported by the paper discharge rib 52 from the lower side.

Therefore, due to the above-mentioned paper discharge rollers 54 and paper discharge ribs 52, the cockling peaks and valleys of the paper X are maintained in the above-described cycle even on the downstream side of the platen rib 44. At the same time, the peaks and valleys of the cockling are maintained until the paper X is ejected from the inkjet printer by the paper ejection ribs 52. As a result, on the downstream side of the platen rib 44, it is possible to prevent the cycle of the cockling wave from being disturbed so that the peaks due to the cockling of the paper sheet X stick to each other and spread to the upstream side.

Further, by maintaining the peaks and troughs of the paper X at the same cycle from the downstream side of the platen 43 to almost the end of the paper ejection guide 51, the paper X becomes a corrugated plate and is reinforced so as not to be easily folded. Will be done. Then, the paper X is cut at a predetermined length for each printing unit by a cutter (not shown) arranged on the downstream side of the recording head 42 at a certain distance from the recording head 42.

FIG. 4 shows the platen 4 of the above-described embodiment.
It is the schematic which showed the modification of No. 3. In this modification, the parts other than the platen 43 are the same as those in the above example.

On the upper surface of the platen 43, platen ribs 44 are provided as in the above example. In addition, the platen rib 44 is provided at the side edge portion on the downstream side of the platen 43.
After reaching the position of the upper surface 43a of No. 3, it becomes high again. Further, the upper surface 45 having substantially the same height as or lower than the platen ribs 44 (higher than the upper surface 43a in the above example) so as to fill up the space between the platen ribs 44 with a slight gap from the platen ribs 44.
A buried portion 45 having a is provided. That is, the upper surface 45 a of the embedded portion 45 does not project to the head 42 side beyond the upper portion of the platen rib 44. In this example, the height of the upper surface 45a of the embedded portion 45 is slightly lower than the height of the platen rib 44. Further, a wedge-shaped recess 47 (notch) is provided on the lower side of the filling portion 45 in the transport direction of the paper X, and the boundary portion between the upper surface 45 a of the filling portion 45 and the surface of the recess 47 is an inclined portion. It is 46. The wedge-shaped recess 4
Reference numeral 7 is a recess 47 formed so as to widen toward the downstream side. In addition, the filling portion 45 and the platen rib 4
4 are arranged at a slight distance from each other, and a groove is formed between them, and the bottom of the groove 48 is the upper surface 4
It has a height of 3a. Further, the bottom of the recess 47 is also at the height of the upper surface 43a, and the bottom surfaces of the groove 48 and the recess 47 are substantially the upper surface 43a of the above example. The heights of the bottoms of the grooves 48 and the recesses 47 are not limited to this, and the embedded portions 45 and the upper surfaces 45a of the pre-point ribs 44,
It should be lower than 44a.

By providing the filling portion 45 between the platen ribs 44, the paper X is supported on the upstream side of the platen 43, that is, in the portion where the paper X before the ink is sufficiently infiltrated during printing is supported. The part corresponding to the space between the X platen ribs 44 is slightly on the upper surface 43a.
It is prevented from sinking toward. As a result, in this portion, the distance between the recording head 42 and the surface of the paper X becomes substantially constant. Therefore, the recording head 4 faces the paper X.
When the ink is ejected from No. 2, it is possible to suppress the occurrence of the unevenness of the coloring density due to the ink due to the deviation of the landing position of the ink.

Further, at the downstream side of the platen rib 44, when the paper X is infiltrated with ink for the first time and the expansion of the paper X starts, the width of the upstream side of the recess 47 is narrow, so that the paper X is recessed. The portion between the platen ribs 44 of the paper X corresponds to the concave portion 47 moving toward the downstream side and widening while the ink soaking progresses without largely sinking in the portion of the sheet X. Will gradually sink. Therefore, the platen 43
Since the peaks and valleys having the desired amplitude are not formed suddenly on the downstream side of the sheet X, it is possible to minimize the occurrence of density unevenness due to the deviation of the ink landing position. it can.

Further, since the above-mentioned concave portion 47 is provided on the downstream side of the filling portion 45 in the conveying direction, the paper X
A cock ring having substantially the same amplitude as when the buried portion 45 is not provided is formed on the. Therefore, the paper can be discharged in a state where the cockling cycle and amplitude are adjusted to be substantially constant. As a result, as in the above example, it is possible to avoid rubbing between the paper X and the recording head 42, and it is possible to ensure good print quality.

Here, assuming that the height of the main filling portion 45 is substantially the same as the height of the platen rib 44, the height position of the upper surface 45a of the filling portion 45 of the platen 43 should be the height of the entire upper surface of the platen 43. You can When interpreted in this way, the platen rib 44 is attached to the upper surface 43a of the platen 43.
It is considered that the groove 48 is formed in the upper surface (upper surface 45a) of the platen 43 between the platen rib 44 and the filling portion 45, and the recess 47 is formed instead of forming the filling portion 45. be able to.

That is, a plurality of sets of two grooves 48 are formed at a position on the upper surface of the platen 43 between the platen ribs 44 and the filling portion 45, and the grooves 4 of the two grooves 48 of the same set are formed.
It can be considered that the concave portion 47 is formed on the downstream side between the eight members. In this case, the grooves 4 in the same group
8, the interval between the sets of the grooves 48 becomes narrower, and the recess 47 is formed in a portion where the intervals between the grooves 48 are wider among the intervals of the formed grooves 48. It should be noted that the basic configuration is similar to that of the embedding unit 45 only by changing the viewpoint.
Since it is the same as the platen 43 having the above, the same effect can be obtained even in such a platen 43.

The present invention is not limited to the above-mentioned embodiments, and it is needless to say that specific detailed structures and the like can be appropriately changed. For example, the shape of the recess 47 is not limited to the wedge shape, and the shape gradually widens toward the downstream side or the shape in which the entire downstream side is a recess, that is, the filling portion 45 is provided on the downstream side. It does not matter if it has no shape

[0059]

According to the ink jet printer according to the first to third aspects of the present invention, the cycle and amplitude of the peaks and valleys when cockling occurs on the recording medium can be adjusted to be substantially constant at the platen position. Therefore, it is possible to prevent a wave having a large amplitude such that the recording medium comes into contact with the head from being generated, and the period of the wave generated on the recording medium is disturbed to increase the amplitude to thereby cause a gap between the recording medium and the head. Rubbing can be avoided. Further, it is possible to ensure good print quality by keeping the distance between the head and the recording medium substantially constant while maintaining the above effects.

According to the ink jet printer of the fourth to seventh aspects of the present invention, as described above, the cycle and amplitude of peaks and troughs when cockling occurs on the recording medium at the position of the platen are adjusted to be substantially constant. , That state can be maintained even on the downstream side of the platen. Therefore, it is possible to surely prevent a situation in which adjacent peaks are stuck to each other on the downstream side of the platen and the amplitude is increased, which ripples to the upstream side of the recording medium and the recording medium comes into contact with the head. Also,
On the downstream side of the platen from the platen of the recording medium, the recording medium is in a state of being reinforced by peaks and troughs, and it is possible to prevent the recording medium from being broken.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an inkjet printer according to an embodiment of the present invention as viewed in a lateral direction.

FIG. 2 is an enlarged view of a recording head peripheral portion of the inkjet printer according to the present embodiment.

FIG. 3 is a schematic diagram for explaining a positional relationship among a platen, a platen rib, a paper ejection rib, a paper ejection roller, a paper ejection roller and the like of the inkjet printer according to the present embodiment.

FIG. 4 is a schematic diagram for explaining a positional relationship between a platen, a platen rib, and a filling portion in a modified example of the present embodiment.

[Explanation of symbols]

1 Inkjet Printer 2 Main Body Frame 3 Paper Feeding Section 31 Spindle 32 Paper Feeding Guides 33a, 33b Conveying Rollers 4 Printing Section 41 Carriage 42 Recording Head 43 Platen 43a Upper Surface 44 Platen Rib 45 Embedded Area 45a Upper Surface 46 Slope 47 Concave 48 Groove 5 Discharge Part 51 Paper ejection guide (ejection guide means) 52 Paper ejection rib (second guide member) 53 Rotating shaft 54 Paper ejection roller (ejection guide means, first guide member) 55 End paper ejection roller X Paper

Claims (7)

[Claims] 1. A transport unit for transporting a sheet-shaped recording medium, a head for ejecting ink onto the recording medium transported by the transport unit for printing, and a recording medium for printing by the head on the back side. An ink jet printer including a platen arranged to face the head so as to be supported from the side, wherein the platen extends along a transport direction of a recording medium by the transport unit and the head. An inkjet printer having a plurality of platen ribs projecting to the side, and an embedded portion having an upper surface that does not project to the head side from the upper part of the platen ribs at least on the upstream side in the transport direction between the plurality of platen ribs. Printer. 2. A transporting means for transporting a sheet-shaped recording medium, a head for ejecting ink onto the recording medium transported by the transporting means for printing, and a recording medium for printing by the head on the back side. An ink jet printer including a platen arranged to face the head so as to be supported from the side, wherein the platen extends along a transport direction of a recording medium by the transport unit and the head. A plurality of platen ribs protruding to the side, and between the plurality of platen ribs, the platen ribs are provided with an interval, with an upper surface that does not protrude to the head side from the upper part of the platen ribs,
An ink jet printer, comprising: a filling portion having a notch that widens toward the downstream side in the transport direction. 3. A conveying unit for conveying a sheet-shaped recording medium, a head for ejecting ink onto the recording medium conveyed by the conveying unit for printing, and a recording medium for printing by the head on the back side. An ink jet printer including a platen arranged to face the head so as to be supported from the side, and extending in parallel to each other along the conveyance direction of the recording medium by the conveyance means on the platen. An ink jet characterized in that a plurality of sets of grooves formed as a set of two and a recess between the grooves of the set of two and a recess that widens toward the downstream side in the transport direction are provided. Printer. 4. The ink jet printer according to claim 1, further comprising a paper discharge roller and a paper discharge guide on the downstream side of the platen in the transport direction, wherein the paper discharge roller is provided between the plurality of platen ribs. Is provided so as to come into contact with the printing surface of the recording medium in an area extending in the transport direction, and the paper ejection guide is an area corresponding to a position where the platen rib is extended in the transport direction and the recording medium An ink jet printer having a discharge rib protruding so as to guide it from the side. 5. A conveyance unit that conveys a sheet-shaped recording medium, a head that ejects ink onto the recording medium that is conveyed by the conveyance unit to perform printing, and a recording medium on which printing is performed by the head is a rear surface. An ink jet printer comprising: a platen arranged to face the head so as to be supported from the side, wherein the platen extends in the platen transport direction of the recording medium by the transporting unit and the head. A plurality of platen ribs projecting to the side, and a discharge guide means for guiding the recording medium substantially along the carrying direction downstream of the platen in the carrying direction, the discharge guiding means comprising the plurality of platen ribs. A first guide member provided so as to come into contact with the printing surface of the recording medium within a region extending in the conveyance direction, and the platen rib. Serial in a region corresponding to a position extending in the conveying direction, ink jet printers characterized in that it comprises a second guide member which projects so as to guide the recording medium from the back side. 6. A conveyance unit configured to convey a sheet-shaped recording medium, a head configured to eject ink to perform printing on the recording medium conveyed to the conveyance unit, and a recording medium to be printed by the head disposed on a back surface. An ink jet printer including a platen arranged to face the head so as to be supported from the side, wherein the platen extends along the conveying direction of the recording medium by the conveying unit and the head side. A plurality of platen ribs protruding in the direction of the platen, and a discharge roller and a discharge guide on the downstream side of the platen in the transport direction, the discharge roller extending between the plurality of platen ribs in the transport direction. Is provided so as to be able to come into contact with the printing surface of the recording medium within the area, and the paper ejection guide corresponds to a position where the platen rib is extended in the transport direction. An ink jet printer characterized in that a discharge rib protruding so as to guide the recording medium from the rear side is provided in a certain area. 7. The ink jet printer according to claim 4 or 6, wherein an end paper discharge roller is provided downstream of the platen in the transport direction so as to come into contact with a side edge of a print surface of a recording medium. An ink jet printer characterized in that the end discharge rollers have a diameter larger than that of the discharge rollers.