JP2002225358A - Image recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image recorder wherein it is possible to prevent a paper from being floated from a paper support means even when the paper has bends at both ends of the paper in a widthwise direction, to prevent an image recording means from being damaged without markedly lowering the image quality, and to prevent the paper from being jammed at a portion between the image recording means and the paper support means. SOLUTION: This image recorder comprises the paper support means 38a1 for supporting a paper in a conveying condition, a sucking means for sucking the paper on the paper support means, and the image recording means for recording an image on the paper conveyed on the paper support means to be sucked by the sucking means. The paper support means includes a first paper support face S1 with which the both end sections of the paper in the widthwise direction are contacted, and a second support face S2 with which the intermediate section positioned between the both end sections in the widthwise direction Y is contacted. The length of the contacted surface of the first paper support face S1 along a paper conveyance direction X is set to be greater than the length of the contacted surface of the second support surface S2 along the paper conveyance direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an image recording apparatus,
In particular, the present invention relates to an image recording apparatus that records an image while supporting a sheet on a platen.

[0002]

2. Description of the Related Art Various types of image recording apparatuses of this type are known. In recent years, ink jet recording methods have been widely used because they are relatively inexpensive and small.

In an image recording apparatus of an ink jet recording system (hereinafter, referred to as an ink jet printer), a sheet is intermittently conveyed by a conveying means such as a nipple roller, and the sheet is usually called a platen during the conveyance. It is supported on paper support means. While the sheet being transported is stopped on the platen, ink is ejected toward the sheet on the platen by the ink jet head constituting the image recording means in this ink jet printer, and a desired image is formed on the sheet. Is done.

In order to obtain a desired image quality in an ink jet printer, it is necessary to keep a predetermined distance (for example, 1 to 2 mm, preferably 1 mm or less) between a sheet on a platen and an ink jet head. Therefore, if the paper floats above the platen by more than this predetermined distance, not only the desired image quality is not obtained, but also the inkjet head collides with the paper, and as a result, the fine inkjet nozzles of the inkjet head may be damaged. Deform or break. Further, in addition to such a result, the paper colliding with the inkjet head has a high possibility of causing a paper jam between the inkjet head and the platen. As described above, the ink jet printer has a technical problem that it is necessary to sufficiently suppress the sheet on the platen from rising from the sheet supporting surface.

A structure for preventing such a floating of a sheet from a platen in an ink jet printer is known from, for example, JP-A-8-156351 and JP-A-9-220837. These two
Each of the two publications discloses a plurality of elongated grooves formed extending in the paper transport direction at a plurality of positions on a flat paper support surface of a platen in a direction orthogonal to the paper transport direction. Then, by sucking air from the plurality of elongated grooves, the sheet is attracted to the sheet supporting surface of the platen,
The paper is prevented from rising from the paper support surface.

[0006]

In the field of image recording devices, improving the image recording speed is an eternal problem. One answer to this problem in inkjet printers is to increase the size of the inkjet head in the paper transport direction. As a result, the dimension of the platen in the paper transport direction must necessarily be increased to correspond to the dimensions of the inkjet head.

However, in this case, if a long platen is used, the possibility that the above-mentioned problem of floating of the paper occurs increases.

The following are conceivable reasons why this problem occurs.

(1) At both ends in the width direction of the paper, residual stress generated when the paper is trimmed to a predetermined width direction during the manufacture of the paper becomes apparent, and the influence of moisture absorption after the manufacture of the paper. As a result, the paper is likely to be extended in the paper transport direction, and as a result, the paper is likely to be wavy in the paper transport direction at both ends in the width direction of the paper.

In an ink jet printer having a conventional platen whose length in the paper transport direction is relatively short, even if such a paper float occurs, the paper float is applied to the paper support surface corresponding to the recording range on the platen. , And no paper floating appeared on the paper supporting surface corresponding to the recording range on the platen.

(2) Paper floating occurring at both ends in the width direction of the paper for the above-mentioned reason is caused by an increase in the area of the paper support surface due to an increase in the length of the platen and an increase in the area of the paper supported on the platen. It will be very large. In addition, the paper float cannot be reliably brought into close contact with the paper support surface only by the suction force of the platen, and because the length of the paper support surface in the paper transport direction is long, the paper float may escape out of the recording range. Not easily.

(3) Further, the paper floating generated as described above is caused by the fact that the extension in the paper transport direction generated at both ends of the paper is larger than the extension generated at the center of the paper. Therefore, the direction in which the convex portion of the paper float extends coincides with the paper width direction (the direction orthogonal to the paper transport direction X) (see FIG. 6), and the platen disclosed in the two publications mentioned above. It is not sucked into the groove formed on the paper support surface of the paper so as to extend in the paper transport direction. In other words, if the extending direction of the convex portion of the paper floating occurs along the paper transport direction, the paper floating may be able to be sucked into the groove, but the extending direction of the convex portion of the paper floating is Is generated along the paper width direction, it is not possible to effectively suction only by the grooves disclosed in the above two publications extending along the paper conveyance direction.

The present invention has been made in view of the above circumstances, and an object of the present invention is to lift a sheet from a sheet supporting surface of a sheet supporting means even if the sheet floats at both ends of the sheet in a direction perpendicular to the conveying direction. As a result, it is possible to prevent the image recording means from being damaged due to the contact with the paper, and further to prevent the paper jam between the image recording means and the paper supporting surface of the paper supporting means. To provide an image recording apparatus capable of performing the following.

[0014]

In order to achieve the above-mentioned object, an image recording apparatus according to the present invention comprises a sheet conveying means for conveying a sheet in a predetermined direction, and an image recording apparatus for recording an image on the sheet. Means, and a sheet supporting means for supporting the sheet at a position facing the image recording means, wherein the sheet supporting means is formed corresponding to both ends in the width direction of the sheet, and the both ends are formed. Are formed corresponding to a first sheet support surface supported along the predetermined direction and a center in the width direction of the sheet, and the second sheet support is supported at the center along the predetermined direction. And a surface,
The ratio of the length of the paper support surface to the predetermined length of the paper support means along the predetermined direction is formed so that the first paper support surface is larger than the second paper support surface. It is characterized by that.

The cause of paper floating is that the lengths at both ends in the paper width direction and the vicinity thereof are longer than the lengths at the center in the paper width direction, whereas the paper support surface of the paper support means is flat. It is because it has become. Therefore, the ratio of the length of the paper support surface to the predetermined length of the paper support means in the predetermined direction (paper transport direction) is set to be smaller than the second paper support surface supporting the center in the paper width direction. By increasing the size of the first sheet supporting surface supporting the end portion in the direction and the vicinity thereof, the extension generated at both ends in the sheet width direction and the vicinity thereof can be adsorbed on the first sheet supporting surface. Can be prevented from contacting the image recording means.

Further, it is preferable that a plurality of recesses are formed on the first paper support surface in the above-described configuration so as to be separated from each other along a predetermined direction.

In order to sufficiently adsorb both ends in the sheet width direction and the vicinity thereof where the paper has been stretched to the first sheet support surface, one large and deep recess is formed in the first sheet support surface. However, in this case, the adverse effect on the image quality of the recorded image is large.

Therefore, by adopting the above configuration, the end portion in the sheet width direction can be attracted to the first sheet support surface, and the adverse effect on the image quality of the image can be reduced.

The recess in the above configuration has a shape as viewed from a direction facing the front surface of the paper support means (a direction perpendicular to the front surface of the paper support means), and the width of the paper support means in the width direction of the paper support means. It is preferable to select from a warhead shape, a semi-elliptical shape, and a semi-circular shape spreading from the center of the means toward the end of the paper supporting means.

In short, the shape of the recess is preferably a shape capable of sufficiently absorbing the floating of the paper generated at the end in the width direction of the paper. It is preferable to make the shape symmetrical to the shape of the paper float generated in the paper. According to the experiments performed by the present inventors, the shape of the paper floating that occurs at the end in the paper width direction when the front surface of the paper support means is viewed from the direction facing the front is from the center of the paper support means to the end of the paper support means. In many cases, it became a warhead shape, a semi-elliptical shape, or a semi-circular shape spreading toward. Therefore, the shape of the recess was made to correspond to the shape of the paper float.

With this configuration, the paper floating generated at the end in the width direction of the paper can be sufficiently absorbed on the paper support surface, and the adverse effect on the image quality of the image can be suppressed.

Hereinafter, various embodiments of the image forming apparatus of the present invention will be described in detail with reference to the accompanying drawings.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a first embodiment of an image forming apparatus according to the present invention will be described in detail with reference to FIGS. In this embodiment, the image forming apparatus is an inkjet recording type inkjet printer.

FIG. 1 is a schematic longitudinal sectional view of a main part of an ink jet printer; FIG. 2 is a main part of the ink jet printer of FIG. A paper feed roll,
FIG. 3 is a schematic front view showing a transport roller and a paper discharge roller as transport means disposed above and below a platen;
FIG. 3A is a schematic front view of a carriage holding six inkjet heads as image recording means in a main part of the inkjet printer of FIG.
FIG. 3B shows the position of the platen block, which is arranged at the left end in the left-right direction, of the seven platen blocks constituting the platen in FIG. 2 in the paper transport direction relative to the carriage in FIG. FIG. 4A is an enlarged front view of a platen block disposed at the center in the left-right direction among the seven platen blocks in FIG. 2; FIG. 4B is a schematic longitudinal sectional view of the platen block of FIG. 4A taken along line BB; FIG. 5A is an enlarged view of the platen block of FIG. 5B is a schematic front view, and FIG.
FIG. 5C is a schematic longitudinal sectional view of the platen block of FIG. 5A taken along line BB. FIG. 5C is a front view of the platen block of FIG. A length L1 in the paper transport direction including a curved bottom surface of the plurality of recesses of the first paper support surface corresponding to one end in the width direction of the transported paper, and a width L1 in the width direction of the paper transported on the front surface. The length L2 of the straight and flat second sheet supporting surface corresponding to the central portion and not including the plurality of recesses in the sheet conveying direction.
FIG. 6A is a diagram showing a comparison between FIG. 6A and FIG. 6A; FIG. 6A is a view showing a residual stress at the time of paper production that becomes apparent when the paper is trimmed at a predetermined width, and a width direction due to moisture absorption after the production. FIG. 7B is an enlarged perspective view schematically illustrating a typical shape of a wavy paper float (a paper float in which a convex portion of the paper float extends in the paper width direction) generated at both ends of the sheet; 6) is an enlarged front view schematically showing a typical shape of the wavy paper float shown in FIG.

As shown in FIGS. 1 and 2, the ink jet printer according to the present embodiment is located at two positions separated from each other in the front-rear direction (the left-right direction in FIG. 1) above the support frame 10. Hold two sheets of paper 11 wound in a roll shape. Each of the papers 11 has the same material and the same size, and in the present embodiment, each paper 11 has a width of 1372 mm (54 inches).
A pair of disc-shaped paper tube holders 12 are concentrically attached to both ends of each of the roll-shaped papers 11. It is rotatably mounted on a pair of roll paper support rollers 16a and 16b provided at two positions. A rotary encoder for detecting the remaining amount of the corresponding roll-shaped paper 11 is connected to one of the pair of roll paper support rollers 16a and 16b.

A nip point between the transport roller 18 and the transport pinch roller 20 is disposed below the support frame 10 between the two roll-shaped sheets 11. The transport roller 18 is constituted by a single roller slightly longer than the width WY0 of the sheet 11, and can be rotated at a predetermined speed in a predetermined direction by a known driving means such as a motor (not shown). I can do it. The transport pinch roller 20 is composed of a plurality of free-rotating rollers that are separated from each other at a predetermined interval in the longitudinal direction of the transport roller 18, and is biased toward the transport roller 18 by a biasing unit (not shown). It is being rushed.

The rolled paper 11 at the front (left side in FIG. 1)
Are drawn out to the nip point between the front paper feed roller 22 and the front pinch roller 24 and the nip point between the transport roller 18 and the transport pinch roller 20 via the front paper guide path 26. The front paper feed roller 22 can be rotated at a predetermined speed in a predetermined direction by a known driving means such as a motor (not shown). A front paper feed sensor 28 that detects the presence or absence of the paper 11 is disposed in the front paper guide path 26.

The rear (right side in FIG. 1) roll-shaped paper 11
Is pulled out to a position just before the nip point between the transport roller 18 and the transport pinch roller 20, that is, immediately above the nip point between the rear paper feed roller 30 and the rear pinch roller 32 and the rear paper guide path 34. . The rear paper feed roller 30 can also be rotated at a predetermined speed in a predetermined direction by a known driving means such as a motor (not shown). A rear paper feed sensor 36 that detects the presence or absence of the paper 11 is disposed in the rear paper guide path 34.

The support roller 10 also includes a transport roller 1.
A platen 38 functioning as a sheet supporting means is disposed below and behind the nip point between the transfer pinch roller 8 and the transport pinch roller 20 (right side in FIG. 1). The front surface 39 of the platen 38 extends two-dimensionally in the paper transport direction and the paper width direction.
As is clear from FIG. 2, the sheet 11 has a width WP slightly longer than the width WY0.

The platen 38 is composed of seven platen blocks 38a1 to 38a7 in the sheet width direction (the horizontal direction in FIG. 2).
And are combined adjacent to each other. The platen blocks 38a1 to 38a7 are platen stays 10a fixed to the support frame 10.
Are detachably fixed by known fixing means such as fixing screws. Platen blocks 38a1-38a
7 has the same configuration as each other except for the two platen blocks 38a1 and 38a7 located at both ends in the paper width direction. However, the two platen blocks 38a1 and 38a7 at both ends also have most of the configuration. Are the same as the respective configurations of the platen blocks 38a2 to 38a6 except for these. The two platen blocks 38a1 and 38a7 at both ends in the sheet width direction are symmetrical with respect to the center in the sheet width direction.

The platen stay 10a is covered with an air-tight material except for a portion to which the seven platen blocks 38a1 to 38a7 are fixed. 38b. The platen stay 10a is provided with a suction fan 43 as suction means for making the platen chamber 38b a negative pressure.

A paper cutter 46 is attached to the lower end of the platen stay 10a. Below the paper cutter 46, a nip point between a paper discharge roller 48 fixed to the support frame 10 and a paper discharge pinch roller 50 is provided. Are located. Further, a paper discharge sensor 51 is disposed between the paper cutter 46 and the paper discharge roller 48.

In this embodiment, the combination of the front paper feed roller 22 and the front pinch roller 24, the combination of the conveyance roller 18 and the conveyance pinch roller 20, and the combination of the paper ejection roller 48 and the paper ejection pinch roller 50 are described. The combination constitutes a sheet transport unit for transporting the front roll-shaped sheet 11 in a predetermined direction, and the combination of the rear paper feed roller 30 and the rear pinch roller 32,
The combination of the transport roller 18 and the transport pinch roller 20 and the combination of the discharge roller 48 and the discharge pinch roller 50 constitute a paper transport unit for transporting the rear roll-shaped paper 11 in a predetermined direction. are doing.

In the support frame 10, the platen 38
2, a carriage 52 on which a plurality of ink jet heads for ejecting a plurality of types of inks having different densities are mounted as image recording means. FIG. 3A shows a plurality of inkjet heads.
As shown in detail therein, six ink jet heads K, C, M, which eject ink of six colors (black, cyan, magenta, light cyan, light magenta, yellow) to form an image in full color. LC, L
M and Y are included.

The above three ink jet heads K, C,
M is arranged on the surface of the carriage 52 facing the platen 38 so as not to overlap with each other in the sheet conveyance direction, and is sequentially shifted to one side in the sheet width direction of the platen 38 toward the lower side. The three ink jet heads LC, LM, and Y are arranged below the three ink jet heads K, C, and M like the three ink jet heads K, C, and M. I have. Each of the six ink jet heads K to Y has a nozzle row L of a predetermined number of nozzles arranged at the same predetermined intervals in the paper transport direction. Although the nozzle rows L of the six ink jet heads K to Y are shifted in the paper width direction, they are arranged at the same predetermined interval from each other if attention is paid only to the paper transport direction.

Above and below the carriage 52, two moving guide rods 54 extending horizontally in a mutually parallel state are arranged.
Fixed to.

The two moving guide rods 54 are also parallel to the front surface of the platen 38, and the carriage 52
The guide is provided so as to be able to reciprocate in parallel with the reference numeral 8. A linear encoder 58 for detecting the position of the carriage 52 in the paper width direction is interposed between the carriage 52 and the upper moving guide rod 54.

The carriage 52 can reciprocate along two moving guide rods 54 within a predetermined range by known reciprocating drive means (not shown). This predetermined range is the carriage 5
This is between the home position of No. 2 and the reversal position during the reciprocation. The carriage 52 is further provided with a paper edge detection sensor 60 at a position corresponding to the upper end of the front surface 39 of the platen 38.

Next, the structure of the platen 38 will be described in more detail with reference to FIGS.

Each of the platen blocks 38a2 to 38a6 located at the center of the platen 38 has a flat front surface 39 like a typical platen block 38a2 shown in FIGS. 4A and 4B. A plurality of positions at predetermined intervals along a paper width direction Y (horizontal direction in FIG. 4A) orthogonal to the transport direction X (a direction from top to bottom in FIGS. 4A and 4B). And has a plurality of grooves 40 extending parallel to each other in the sheet transport direction X. The dimension of each of the plurality of grooves 40 in the sheet width direction Y, that is, the groove width is set within 20 times the thickness of the thinnest sheet used in this inkjet printer.

Each of the plurality of grooves 40 has a sheet conveying direction X
A first suction through-hole 41 is formed at the upstream end of the groove 40 in FIG. These first suction through holes 41 are formed in a straight line with each other in the sheet width direction Y. In addition,
As for the other platen blocks, the first suction through holes 41 are formed at the upstream ends of the plurality of grooves 40 in the sheet conveyance direction X. As a result, the first suction through holes are formed in the entire platen 38. 41 is formed on a straight line.

In each of the plurality of grooves 40, a plurality of second suction through-holes 42 are formed at the same predetermined intervals in the direction in which the grooves 40 extend (paper transport direction). Further, in two grooves 40 adjacent to each other, one of the grooves 4
The second suction through-hole 42 of the other groove 40 is located at substantially the center of the interval between two adjacent second suction through-holes 42 in one groove 40 with respect to the second suction through-hole 42 of zero. It is arranged as follows.

In FIGS. 4A and 4B, in order to prevent the drawings from being complicated, all of the plurality of grooves and the first and second suction through-holes correspond to these. Are not indicated by reference numerals 40, 41, and 42.

The portion of the front surface 39 of the platen block 38a2 where the plurality of grooves 40 are not formed is the paper 11
Constitute a sheet supporting surface that is slid and conveyed. That is, the front surface 39 excluding the groove 40 constitutes the sheet supporting surface. The paper support surface has been subjected to a friction reduction process to reduce friction generated between the paper support surface and the paper 11 that is in sliding contact with the paper support surface. In the present embodiment, Teflon (registered trademark), which is a kind of friction reduction material, is used as the material. Covered on the paper support surface.

Next, FIGS. 3B, 5A and 5B
The configuration of the platen block 38a1 disposed at the left end of the two platen blocks 38a1 and 38a7 at both ends in the paper width direction will be described in detail with reference to FIG. Components that perform the same functions as the components of the platen block 38a2 described above are denoted by the same reference numerals as those used in the description of the platen block 38a2, and detailed description thereof will be omitted.

As shown in FIG. 3B, in the platen block 38a1, at a portion corresponding to the left end portion in the sheet conveying direction X and the sheet width direction Y, at a plurality of positions along the sheet conveying direction X, Seven recesses 44a, 44b, 44c, 4
4d, 44e, 44f and 44g are formed. This 7
Six recesses 44b-4 of the four recesses 44a-44g
4g is a carriage 5 as shown in FIG.
6 are moved along the front surface 39 of the platen block 38a1, and the six inkjet heads K, C, M, LC,
The movement trajectories T1, T2, T3, and LM of the nozzle rows L of LM and Y, respectively.
The recesses 44a correspond to T4, T5, and T6, and are formed so as to correspond to the upstream side of the movement trajectory T1 of the nozzle row L of the ink jet head K on the most upstream side in the paper transport direction X.

The shapes and dimensions of the recesses 44a to 44g are the same as each other, and the shape of the front surface 39 as viewed from the front as shown in FIG. It has a so-called warhead shape or semi-elliptical shape that gradually opens outward (edge) of Y and gradually closes inward (center) in the paper width direction Y. Further, as shown in FIG. 5B, the cross section of each bottom surface of the recess along the sheet transport direction X is from the front surface 39 to the rear (FIG. 5B).
It is formed as a curved surface that is concave toward (B, middle, right). Further, the cross section along the sheet width direction Y is formed so as to gradually become shallower toward the inside in the sheet width direction Y.

In the present embodiment, these recesses 44a to 44a
The maximum width of each of the 4 g papers along the paper transport direction X is about 30 mm, the maximum width along each paper width direction Y is about 90 mm, and the maximum depth from the front surface 39 is about 1.0 mm. Is set to

Further, in this embodiment, as shown in FIG. 5A, the front surface 3 of the platen block 38a1
9, a plurality of third suction through-holes 45 are formed in portions adjacent to the contours of the seven recesses 44a to 44g and in the bottom surfaces of the recesses, respectively. In FIG. 5B, reference numeral 45 is given only to a part of the third suction through hole in order to avoid complication of the drawing.

The bottom surfaces of the recesses 44a to 44g are preferably processed to have the same surface roughness as the sheet supporting surface of the front surface 39 of the platen block 38a1, and in the present embodiment, Teflon ( (Registered trademark) coating. Further, the recesses 44a to 44g
Of the front shape of the platen block 38a1 and the boundary of the front surface 39 of the platen block 38a1
Are chamfered and rounded so as not to be caught.

Further, the cross section of the front surface 39 along the sheet transport direction X between each of the recesses 44a to 44g is formed by connecting the adjacent two rounded boundaries between the recesses 44a to 44g as described above. It can also be configured as a continuously formed waveform. Of course, the portion of the corrugated shape protruding toward the front surface 39 is formed so as not to protrude forward (toward the inkjet head) from the front surface 39.

Each of these recesses 44a to 44g can be formed by various known processing methods. However, when processing using a metal saw on a milling machine, the direction of rotation of the metal saw is changed to the platen block 38a.
It is preferable to match the sheet conveyance direction X on the front surface 39 of the printer 1. Because, as a result, a cutting trace formed on the bottom surface of the recess is formed along the sheet transport direction X, the paper 11 conveyed on the front surface 39 is caught by the cutting trace at the bottom surface of the recess. It is because it can suppress. In other words, even if the processing is relatively rough, the occurrence of paper jam can be suppressed, which leads to a reduction in the manufacturing cost of the platen block.

In each of these recesses 44a to 44g, the distance in the sheet transport direction X of the plane (front surface 39) between the adjacent boundaries of two adjacent recesses is 10
It has been found that it is more preferable to secure the length in mm. If the distance of the plane between the boundaries is shorter than this, the stiffness of the paper 11 itself is reduced by the third paper suction hole 45 formed in the plane between the boundaries. Overcomes the suction force generated by the third sheet, and the plane between the boundaries (front 3
This is because the possibility of no close contact with 9) increases.

Further, as shown in FIG. 3B and FIG. 5A, the straight portions extending in the sheet conveying direction X in the contours of the front shapes of the recesses 44a to 44g are platens. It is preferable that the sheet 11 conveyed on the front surface 39 of the block 38a1 is positioned outward in the direction Y perpendicular to the left end in the width direction of the sheet 11 conveyed. This is because, by this, each of the recesses 44a-44g can better fulfill their original function as described below.

As shown in FIG. 5A, the front surface 39 of the platen block 38a1 has a front surface 39 on which the plurality of grooves 40 are not formed.
Concave portions 44a to 44g are formed in a region facing the left end in the width direction of the paper 11 conveyed above and extending in the paper conveyance direction X. Hereinafter, this region is defined as a first paper support surface S1. I do. Also, on the paper supporting surface, a front surface 39 is provided.
The recess 44 facing the center of the sheet 11 conveyed above in the width direction.
An area where a to 44g is not formed is hereinafter defined as a second paper support surface S2. The platen block 38a
7 also has a first paper support surface S1 which is an area extending in the paper transport direction X where the recesses 44a to 44g are formed, but the description thereof is omitted here.

Then, as shown in FIG. 5C,
The length L1 of the sheet supporting surface including the curved bottom surfaces of the recesses 44a to 44g of the first sheet supporting surface S1 in the sheet conveying direction X is longer than the length L0 of the front surface of the platen in the sheet conveying direction. .

On the other hand, the linear flat length L2 of the second paper support surface S2 in the paper transport direction X not including the recesses 44a to 44g is equal to the length L0 of the front surface of the platen in the paper transport direction. Compared to be the same.

That is, the ratio of the sheet conveying surface to the same predetermined length in the sheet conveying direction length of the platen is the second
The first paper support surface is larger than the first paper support surface. This is because the concave portions 44a to 44g formed on the first sheet supporting surface are elongated only by the curved portions on the bottom surface.

Next, the operation of the ink jet printer according to the present embodiment will be described in detail with reference to FIGS.

When the ink-jet printer starts operation, the front roll-shaped long paper 11 on the support frame 10 moves through the nip point between the front paper feed roller 22 and the front pinch roller 24 and the front paper guide path 26. The paper 11 is pulled out to the nip point between the transport roller 18 and the transport pinch roller 20 via the transport roller 18, and the leading edge of the paper 11 is detected by the paper leading edge detection sensor 60 located at the upper end of the platen 38. During this time, the carriage 52 is disposed at one of the standby positions on the pair of movement guide rails 54 on either side of the platen 38 in the left-right direction.

As shown in an enlarged manner in FIGS. 6A and 6B, both ends in the width direction of the sheet 11 are provided in the sheet conveying direction X.
In many cases, a continuous paper float 11 'is generated along. When viewed from a direction perpendicular to the plane of the sheet 11, these sheet floats 11 'have a so-called warhead shape or a substantially semi-elliptical shape that gradually expands from the inside of the sheet toward the end in the sheet width direction. There are many. The protruding portion of the paper float extends along the paper width direction, and its height is often increased toward the paper width direction end.

After the sheet edge detection sensor 60 detects the sheet 11, the conveying roller 18 and the conveying pinch roller 20
The paper 11 is moved to the inkjet head K for black ink.
Is conveyed to just before the uppermost stream end of the nozzle row L in the paper conveying direction X. Next, the paper 11 is transported so as to cover the nozzle row of the inkjet head K on the carriage 52, and thereafter, the paper 11 is transported intermittently in units of the length of the nozzle row L. As a result, the sheet 11 is guided on the front surface 39 of the platen 38.

While the transport roller 18 and the transport pinch roller 20 are intermittently transporting the paper 11, the suction fan 43
Is operated. As a result, the negative pressure generated through the first suction through hole 41 at the upper end of the platen 38 is
The sheet 11 that has reached the upper end of the sheet 9 is sucked to the front surface 39.

Here, the recesses 44a to 44g are formed on the front surface 39.
On the second sheet supporting surface S2 at the center of the platen 38 where no is formed, the center of the sheet 11 in the width direction is sucked by the negative pressure generated through the second suction through hole 42.

On the first paper support surface S1 provided at the end in the direction Y perpendicular to the platen 38 where the recesses 44a to 44g are formed on the front surface 39, in addition to the second suction through hole, Negative pressure generated through the bottom surfaces of the recesses 44a to 44g and the third suction through holes 45 around the bottoms sucks the widthwise end of the sheet 11.

The grooves 40 on all front surfaces 39 of the platen blocks 38a1-38a7 allow the suction of the paper 11 onto the front surface 39 as described above, while the front surface 39
The above-mentioned intermittent conveyance of the sheet 11 along the line is also possible. Moreover, the frictional force generated between the front surface 39 and the front surface 39 during the intermittent conveyance is increased, and the smooth conveyance of the sheet 11 is prevented, thereby preventing the sheet 11 from rising.

Further, as described above, the width of the plurality of grooves 40 in the direction Y orthogonal to each other is set within 20 times the thickness of the thinnest paper used in this ink jet printer. Even if the sheet is thin, the sheet 11 does not enter the groove 40.

Further, as shown in FIG. 5C, on the first sheet supporting surface S1 on the platen 38, which supports both ends in the width direction of the sheet 11, as described above, there are seven curved portions. Since the concave portions 44a to 44g are formed, the length L1
Is longer than the length L2 of the paper support surface in the paper transport direction X of the second paper support surface S2 having a flat paper support surface. For this reason, the extension generated at both ends in the width direction of the sheet 11 can be absorbed by the first sheet supporting surface S1. That is, even if the paper float 11 'as shown in FIG. 6 is generated, the negative pressure from the second suction hole 42 and the third suction through hole 45 causes the protrusion of the paper float 11' from the front surface 39. The portion is sucked into the seven concave portions 44a to 44g and becomes a convex portion facing rearward, so that both ends in the width direction of the sheet 11 may protrude forward (toward the inkjet head) from the front surface 39 of the platen 38. Absent. In addition, even while the paper 11 is being intermittently conveyed, the paper floats 11 ′ generated at both ends of the paper 11 are sucked into the seven recesses 44 a to 44 g, and the convex portions of the paper floats 11 ′ come from the front surface 39. It does not protrude forward. Also, since the shape of each of the seven recesses 44a to 44g is similar to the shape of the paper float 11 'generated at both ends in the width direction of the paper 11, the paper float 11' generated at both ends of the paper 11 is The bottoms of the three recesses 44a to 44g are better drawn along, are slid better, and are sucked into the bottoms.

It should be noted that paper floats 1 are provided at both ends in the width direction of the paper 11.
If 1 'does not occur, or if paper float 11' occurs and is extremely small, both ends of paper 11 are recessed 44a to 44a.
It only slightly recesses toward 44g and does not touch the bottom surfaces of the recesses 44a to 44g. However, even when the paper 11 is intermittently conveyed, both ends of the paper 11 do not protrude forward of the front surface 39 from inside the recesses 44a to 44g due to the suction force from the third suction through hole. .

Each time the sheet 11 conveyed intermittently while being sucked by the front surface 39 of the platen 38 is temporarily stopped, the carriage 52 moves leftward or rightward.
Each of the inkjet heads K, C, M, LC, LM, and Y ejects ink toward the paper 11 based on the image information while the carriage 52 is moving to form a desired image on the paper 11. . In order to form an image in this manner, the carriage 52 is moved to the left and right sides 3
9, the carriage 52 does not protrude forward from above the front surface 39, regardless of whether or not the paper 11 has paper floats 11 'at both ends in the width direction. There is no collision or contact with 11.
For this reason, the ink jet heads K, C, M, LC, LM, and Y on the carriage 52, particularly, the nozzle holes are not damaged, and the paper 11 colliding with each ink jet head is brought into contact with the front surface 39 of the platen 38. Carriage 5
There is no paper jam between the two.

Further, since the center of the sheet 11 in the width direction is sucked onto the flat second sheet supporting surface S2 of the front surface 39 of the platen 38, the ink jet heads K, C, M, LC, LM on the carriage 52 are provided. , Y and the paper 11 are always kept at a predetermined value that maximizes the image quality of the image.

Further, both ends in the width direction of the sheet 11 are also sucked on the first sheet supporting surface S1 in which the seven concave portions 44a to 44g of the front surface 39 of the platen 38 are formed. Although the distance between each of the ink jet heads K to Y and the paper 11 is slightly increased, the image quality of the image is not significantly reduced.

After the sheet 11 on which the desired image has been formed is detected by the sheet ejection sensor 50 below the platen 38, the sheet ejection roller 48 and the sheet ejection pinch roller 5 further below the sheet 11 are detected.
It is nipped at a nip point of 0, and is further discharged downward at a predetermined speed. The paper ejection sensor 50 is
Is detected for a predetermined time, that is, after the paper 11 moves a predetermined length on the front surface 39 of the platen 38 for recording an image, the paper cutter 46 moves the paper 11 of the predetermined length on which the image is recorded. Cut off.

When the front roll sensor 11 no longer detects the paper 11 and the front edge sensor 60 no longer detects the paper 11, the rear paper feed roller 30 and the rear pinch The roller 32 draws the paper 11 from the rear roll-shaped paper 11 to the nip point between the transport roller 18 and the transport pinch roller 20 via the rear paper guide path 34. Further, the transport roller 18
And the transport pinch roller 20 and the rear roll-shaped paper 11
Is pulled out until the leading end of the sheet 11 is detected by the sheet end detection sensor 60 corresponding to the upper end of the platen 38, the conveyance of the sheet 11 is stopped, and preparation for the next image recording is performed. Do.

In this embodiment, the platen 38
Platen blocks 38a1 at both ends in the left-right direction of FIG.
The number, arrangement, shape, size, etc. of the seven recesses 44a to 44g of the respective
Paper floating 1 generated at both ends in the width direction of paper 11 conveyed above
It is preferable to design the number and arrangement of 1 'so as to be substantially equal to each shape and size. The number, arrangement, shape, size, and the like of the paper floats 11 'generated at both ends in the width direction of the paper 11 can be predicted to some extent by experiments, statistics, and the like according to the material and dimensions of the paper 11, the manufacturing process, and the degree of moisture absorption. Become.

The number, arrangement, shape and size of the recesses formed on the front surface 39 of the platen 38 do not necessarily correspond to the paper floating 11 'to be generated.
The suction can be performed in the recesses formed in each of the three platen blocks 38a1 and 38a7, without projecting forward from the front surface 39, and it is only necessary that the carriage 52 and the inkjet heads K to Y do not collide with or come into contact with each other.

Therefore, if such a condition is satisfied, the recess formed on the front surface 39 of the platen 38
It is not necessary to form them in correspondence with the movement trajectories of the nozzle rows L of the six inkjet heads K to Y on the second.

(Second Embodiment) For example, FIGS. 7A and 7B show that the first sheet supporting surface S1 of the front surface 39 has a recess 4 on the assumption that the above-described conditions can be satisfied.
A front view and a sectional view of an example of a platen block 38a1 in which only one 4a is formed are shown.

In this embodiment, a large number of third suction through-holes 45 are formed in the first sheet supporting surface S1 in a portion other than the bottom surface of the recess 44a and its periphery. With this configuration, both ends of the sheet 11 that is easily lifted from the first sheet supporting surface S1 due to the presence of the sheet floating 11 ′ are held at the recesses 44a on the first sheet supporting surface S1. Can be absorbed, and it can be prevented from floating forward from the front surface 39.

Then, on the first paper support surface S1,
The ink jet heads K, C, M,
If there is no recess 44a corresponding to the transport trajectory (see FIGS. 3A and 3B) in the direction Y orthogonal to the nozzle rows L of LC, LM, and Y, the first portion other than the recess 44a is used. The flat portion of the paper support surface S1 corresponds to the transport trajectory of each of the nozzle rows L of the six inkjet heads K to Y.

Therefore, if the embodiment shown in FIGS. 7A and 7B is adopted, the image quality of the image formed on the paper 11 supported on the first paper support surface S1 and the second The image quality of the image formed on the paper 11 supported by the paper support surface S2 is the same.

(Third Embodiment) It is dark ink that easily affects the quality of an image formed in an ink jet printer. In the ink jet printer according to the first embodiment, black is the darkest, followed by black. Is cyan or magenta.

FIGS. 8A and 8B show a front view and a sectional view of the platen block 38a1 of the present embodiment.

The collision of the sheet 11 on the platen 38 with the carriage 52, the jamming of the sheet 11 between the carriage 52 and the platen 38, the sheet 1
Assuming that the above-mentioned condition regarding the image quality of the image formed for the first image can be satisfied, the first
Is transported in the sheet width direction Y of the nozzle row L of the inkjet head K using the black ink having the highest density among the inkjet heads K, C, M, LC, LM, and Y on the carriage 52 on the paper support surface S1 of the carriage 52. At a position corresponding to the trajectory (see FIGS. 3A and 3B), only a large number of third suction through holes are formed without forming a recess. Other configurations are the same as those of the first embodiment.

As described above, the transport trajectory of the nozzle row L of the inkjet head K in the paper width direction Y (FIG. 3A)
And (B)), the deterioration of the image quality of the image formed by the black ink can be suppressed. Further, the image quality of the image formed by other inks is an image formed by relatively low-density ink, although a slight decrease is observed particularly on the first paper support surface S1 where the recess is formed. However, a slight decrease in image quality is not so noticeable as a whole. Therefore, the paper floats 11 'generated at both ends in the width direction of the paper 11 can be sucked into the recess, and the deterioration of the image quality of the entire image can be suppressed.

(Fourth Embodiment) This embodiment is a modification of the third embodiment.

FIGS. 9A and 9B are a front view and a sectional view of a platen block 38a1 of the present embodiment.

The collision of the sheet 11 on the platen 38 with the carriage 52, the jam of the sheet 11 between the carriage 52 and the platen 38, the sheet 1
Assuming that the above-mentioned condition regarding the image quality of the image formed for the first image can be satisfied, the first
Of the ink jet heads K, C, M, LC, LM, and Y on the carriage 52, not only the ink jet head K using the black ink having the highest density, but also the cyan ink having the next highest density. Concave portions are also formed at positions corresponding to the transport trajectories (see FIGS. 3A and 3B) of the respective nozzle rows L of the inkjet heads C and M using ink and magenta ink in the paper width direction Y. Instead, only a large number of third suction through holes are formed. Other configurations are the same as those of the first embodiment.

As described above, no recess is formed corresponding to the transport trajectory in the paper width direction Y of each nozzle row L of the inkjet heads K, C, and M using black ink, cyan ink, and magenta ink with high density. In addition, it is possible to suppress deterioration in image quality due to not only black ink but also cyan ink and magenta ink having relatively high density. As a result, it is possible to make the deterioration of the image quality of the entire image inconspicuous. Further, as for the paper floating 11 ′ generated at both ends in the width direction of the paper 11, the recesses 44a, 4
Since the suction is performed in the spaces 4e, 44f, and 44g, it is possible to suppress the floating of the paper float 11 'from coming in front of the front surface 39, and to prevent the problem that the convex portion of the paper float 11' comes into contact with the inkjet head.

(Fifth Embodiment) FIGS. 10A and 10B
Also, the sheet 1 on the platen 38 with respect to the carriage 52
1, the jam of the sheet 11 between the carriage 52 and the platen 38, and the first condition of the front surface 39, assuming that the above-mentioned conditions regarding image quality can be satisfied.
In the sheet support surface S1, the eight recesses 47a, 47b, 47 are independent of the transport trajectory in the sheet width direction Y of each of the nozzle rows L of the six inkjet heads K to Y.
A front view and a cross-sectional view of an example of a platen block 38a1 on which c, 47d, 47e, 47f, 47g, and 47h are formed are shown.

Further, each of these recesses 47a to 47h has the same shape as the recess 44 described in the first to fourth embodiments.
a to 44 g, but have a so-called long warhead shape elongated in the sheet width direction Y.

Also in this embodiment, a large number of third suction through holes 45 are formed on the bottom surface of each of the eight recesses 47a to 47h of the first sheet support surface S1 and the periphery thereof. Both ends in the width direction of the paper 11 are the first paper support surface S1.
To prevent it from rising from

Further, an image on the sheet 11 supported on the eight recesses 47a to 47h of the first sheet supporting surface S1 and an image on the sheet 11 supported on a flat position on the second sheet supporting surface S2. In order to make no noticeable difference between FIG. 1 and FIG.
As shown in FIG. 0 (B), the cross section in the paper transport direction X is formed by a curved surface that is convex toward the rear, and a chamfering R process is performed at the boundary between the concave portion and the front surface 39.

The long warhead-shaped recess is formed on the first paper support surface S1 by the transport trajectory of each of the nozzle rows L of the inkjet heads K to Y in the paper width direction Y (FIG. 3).
(See (A) and (B)), and may be formed at a position corresponding to the nozzle row L of the inkjet head K further upstream as described in the first embodiment. Seven additional ones may be formed at positions corresponding to the sides.

(Sixth Embodiment) FIGS. 11A and 11B
2 shows a front view and a cross-sectional view of the platen block 38a1 of the present embodiment.

This embodiment is an example in which the third embodiment and the fifth embodiment are combined. The position and number of the recesses are the same as in the third embodiment, and the shape and size of the recesses are the same as those in the fifth embodiment. It is the same as.

The operation and effect of this embodiment are the same as the operation and effect described in the third embodiment, and a description thereof will be omitted.

(Seventh Embodiment) FIGS. 12A and 12B
2 shows a front view and a cross-sectional view of the platen block 38a1 of the present embodiment.

This embodiment is an example in which the fourth and fifth embodiments are combined. The position and the number of the recesses are the same as in the fourth embodiment, and the shape and size of the recesses are the same as those in the fifth embodiment. It is the same as the form.

The operation and effect of this embodiment are the same as the operation and effect described in the fourth embodiment, and a description thereof will be omitted.

The number of the long warhead-shaped recesses depends on the collision of the paper 11 on the platen 38 with the carriage 52,
If the above-mentioned conditions regarding the jam of the sheet 11 between the carriage 52 and the platen 38 and the image quality of the image formed on the sheet 11 by the carriage 52 can be satisfied, the number described in each of the above-described embodiments can be satisfied. Not limited. For example, the recess formed in the first paper support surface S1 is a transport locus in the paper width direction Y of each of the six nozzle rows L of the inkjet heads K to Y (see FIGS. 3A and 3B). Irrespective of or one of them, or two or three.

(Eighth Embodiment) Further, by combining a plurality of types of recesses, the nozzle arrays of the six inkjet heads K to Y are provided on the first paper support surface S1 of the front surface 39 of the platen 38a1. The recess may be formed independently of the transport trajectory L in the sheet width direction Y (see FIGS. 3A and 3B) or in combination with any one of the recesses.

FIGS. 13A and 13B are a front view and a sectional view of a platen 38a1 of the eighth embodiment.

In the present embodiment, on the first paper support surface S1, in the paper width direction Y of the nozzle row L of the inkjet head K using the black ink having the highest density among the six inkjet heads KY. The transport trajectory in the paper width direction Y of each nozzle row L of the inkjet heads C and M using the cyan ink or the magenta ink having the second highest density after the black ink without forming a recess at the position corresponding to the transport trajectory in FIG. Warp-shaped recesses 44c and 44d having a short length in the paper width direction Y are formed at positions corresponding to the above, and the remaining inkjet heads LC, LM and
A warhead-shaped recess 49 having a longer length in the paper width direction Y is provided at a position corresponding to each of Y and a position upstream of a position corresponding to the inkjet head K in the paper transport direction X.
a, 49e, 49f, and 49g are formed.

Regarding the depth of the recess, the warp-shaped recesses 49a, 49e, and 49e having a longer length in the sheet width direction Y than the warhead-shaped recesses 44c and 44d having a shorter length in the sheet width direction Y.
49f and 49 are deeper, and a large number of suction through holes 45 are formed in the first sheet supporting surface S1 regardless of whether a recess is formed.

(Ninth Embodiment) FIGS. 14A and 14B
Shows a front view and a cross-sectional view of a platen 38a1 of the ninth embodiment.

In the present embodiment, the shape of the recess formed on the first paper support surface S1 is rectangular. More specifically, on the first paper support surface S1, the inkjet head K that uses the black ink having the highest density among the six inkjet heads KY, and the density next to the black ink is No recess is formed at a position corresponding to the transport trajectory in the paper width direction Y of each nozzle row L of the inkjet heads C and M using dark cyan ink and magenta ink, and other inkjet heads LC, LM and Paper width direction Y of each nozzle row L of Y
And the rectangular recesses 53a, 53e, 53f, 53 at positions upstream of the position corresponding to the transport locus and the position corresponding to the inkjet head K in the paper transport direction X.
g is formed.

Each of the rectangular recesses 53a, 53e, 53f,
The cross-sectional shape of the 53g along the paper transport direction X is a V-shape in which the upstream side in the paper transport direction X is much shorter than the downstream side. This is a configuration for smoothly transporting the paper 11 sucked into the recess from the inside of the recess to the front surface 39.

On the first sheet supporting surface S1,
Regardless of whether or not the recess is formed, a number of third suction through holes 45 are formed.

(Tenth Embodiment) FIGS. 15A and 15B are a front view and a sectional view of a platen 38a1 of a tenth embodiment.

In the present embodiment, the shape of the recess formed on the first paper support surface S1 is rectangular. More specifically, a rectangular recess is provided on the first paper support surface S1 at a position corresponding to the transport trajectory in the paper width direction Y of each of the nozzle rows L of the six inkjet heads K to Y. 55a, 55b, 55c, 55d, 55e, 55f, 5
5 g are formed.

As shown in FIG. 15B, the bottom surface of each of the rectangular recesses 55a to 55g is formed by a curved surface whose cross section in the paper transport direction X is backward.

In the present embodiment, various modifications are also possible. For example, in the first sheet supporting surface S1, the sheet width direction of the nozzle row L of the ink jet head K using the black ink having the highest density is used. The above-described rectangular recess is not formed at a position corresponding to the transport trajectory in Y, and further, each of the inkjet heads C and M that use cyan ink or magenta ink having the next highest density after black ink. The rectangular recess as described above may not be formed at a position corresponding to the transport trajectory of the nozzle row L in the sheet width direction Y.

Further, on the first sheet supporting surface S1, 6
Rectangular recesses can be formed at a plurality of positions irrespective of the transport trajectory in the paper width direction Y of each of the nozzle rows L of the individual inkjet heads K to Y, and the rectangular dimensions can be variously changed. It can be set, and can be formed in various combinations with rectangular recesses of various dimensions and various shapes other than rectangular.

Also in the present embodiment, a large number of third suction through-holes 45 are formed in the first paper support surface S1 regardless of the presence or absence of a recess, and the first paper support surface S1 is provided with the paper float 11 '. One of the two ends of the sheet 11 that easily rises from the first sheet support surface S1 is prevented from rising from the above-mentioned portion where the recess is not formed on the first sheet support surface S1.

(Eleventh Embodiment) In the ink jet printer described above, the dimension in the width direction is 1372.
Although the type in which only paper having a width of 54 mm (mm) can be used, the ink jet printer described below can form a desired image using paper having various other width dimensions. It is a type that can be done. Acceptable paper is 1270 mm (50 inches) or 10
It has a width of 67 mm (42 inches), 914 mm (36 inches), 840 mm (A0 paper) or 594 mm (A1 paper).

FIG. 16 shows a platen of an ink jet printer corresponding to six types of paper widths and a configuration around the platen.

In the platen 38, various paper width dimensions WY0 (1372 mm) and WY1 (1270) are used.
mm), WY2 (1067 mm), WY3 (914 m
m), WY4 (840 mm), and WY5 (594 mm), a warhead-shaped recess is formed on the front surface supporting both ends in the width direction of each sheet. That is, six sets of first sheet supporting surfaces DP0, DP1, DP2, DP3, DP4, and DP5 in which warhead-shaped recesses are formed along the sheet width direction Y are formed.

Each of the first paper support surfaces DP0 to DP
5, seven warhead-shaped recesses and a large number of third through-suction holes are formed along the sheet transport direction X. The formation positions of these seven recesses in the sheet transport direction X are the same as the formation positions of the recesses in the first embodiment.

If such a platen 38 is used, various widthwise dimensions WY0, WY1, WY2, WY3, WY
Regardless of which paper 11 is used among the papers 4 and WY5, the paper floating occurring at both ends in the width direction of the paper 11 is caused by the platen 3 formed corresponding to the both ends in the width direction of each paper.
8, and can be prevented from protruding forward from the front surface 39 of the platen 38.
Therefore, it is possible to suppress damage to the ink jet head and occurrence of paper jam.

The collision of the paper 11 on the platen 38 with each concave carriage 52, the jam of the paper 11 between the carriage 52 and the platen 38, the carriage 52
On the assumption that the above-described conditions regarding the image quality of the image formed on the sheet 11 can be satisfied by the first and second sheet supporting surfaces DP0 to DP5,
The size, number, and arrangement position can be set as appropriate.

For example, in FIG. 17, among the six first paper support surfaces DP0 to DP5, five first paper support surfaces DP0 to DP5 inside the platen are provided.
FIG. 4 is a diagram showing a preferred example of the shape of the recess of the paper support surfaces DP1 to DP5.

When a sheet having a width of WY0 is used for an ink jet printer having a platen 38 on which the first sheet support surfaces DP0 to DP5 are formed, only the widthwise ends of the sheet are used. Instead, the sheet is also supported by the first sheet supporting surfaces DP1 to DP5 at the center in the width direction of the sheet. At this time, if the sheet is slightly extended at the center in the width direction of the sheet, the sheet is sucked into the recesses of the first sheet supporting surfaces DP1 to DP5 by the extension. That is, the first paper support surface D
If the recesses P1 to DP5 have a warhead shape as shown in FIG. 16, the paper portion to be sucked will be sucked along the warhead shape of the recess.

In the case of a warhead-shaped recess, a boundary between the front surface 39 and a straight line portion along the sheet transport direction X exists. Therefore, the paper portion sucked into the recess is formed along the straight line portion. It will be sucked.

However, the paper portion supported at the boundary of the straight line portion sharply bends at the boundary portion as compared with the paper portion supported at another curved boundary, so that the image quality of the image is remarkable. It gets worse.

In view of such inconvenience, the recesses of the first paper support surfaces DP1 to DP5 formed inside the platen 38 are symmetrical and have no linear portion along the paper transport direction X. A shape is preferable, and as an example, an oval shape shown in FIG. 17 is preferable. As another example, a perfect circle may be used.

Although the embodiments based on the present invention have been described, the present invention can be described as follows.

(1) The ratio of the length of the paper support surface to the length of the platen is greater on the second paper support surface than on the first paper support surface. An image recording device that records an image on the sheet, and a sheet supporting unit that supports the sheet at a position facing the image recording unit, wherein the sheet supporting unit includes both ends in the width direction of the sheet. And a first sheet supporting surface whose both ends are supported along the predetermined direction, and a center formed in the width direction of the sheet, and the center is formed along the predetermined direction. And a second paper support surface, wherein the ratio of the length of the paper support surface to the predetermined length of the paper support means along the predetermined direction is the second paper support surface. So that the first paper support surface is larger than And an image recording apparatus.

(2) “A plurality of recesses are formed in the first paper support surface” The first paper support surface includes a plurality of recesses that are spaced apart from each other along the predetermined direction. 2. The image recording apparatus according to claim 1, comprising:

(3) “Opening shape of recess” The shape of the recess viewed from the direction facing the front surface of the paper support means is a warhead shape, semicircular shape, circular shape, elliptical shape,
3. The image recording apparatus according to claim 2, wherein the image recording apparatus is one selected from a rectangular shape.

(4) “A plurality of first paper support surfaces are formed” The paper transport means is capable of transporting a plurality of papers having different widths, and the first paper support means of the paper support means 2. The image recording apparatus according to claim 1, wherein a plurality of surfaces are formed corresponding to both ends in the width direction of the plurality of sheets having different widths.

(5) “Cross-Sectional Shape of Bottom of Recess” The image recording apparatus according to item 2, wherein the bottom of the recess is formed by a curved surface.

(6) “Cross-Sectional Shape of Bottom of Recess” The image recording apparatus according to claim 2, wherein the bottom of the recess is formed by a slope facing the front of the sheet supporting means. .

(7) "Relationship between the number of third suction through-holes on the first and second paper support surfaces" Further, the plurality of suction holes formed on the first and second paper support surfaces are Suction means for sucking a sheet onto the first and second sheet support surfaces via the plurality of suction holes, wherein the number of suction holes formed on the first sheet support surface is The image recording apparatus according to any one of claims 1 to 6, wherein the number of suction holes is greater than the number of suction holes formed on the second paper support surface.

(8) "Relationship of suction force on first and second paper support surfaces" Further, a plurality of suction holes formed on the first and second paper support surfaces and a plurality of the suction holes are formed. And suction means for sucking a sheet on the first and second sheet supporting surfaces via the first sheet supporting surface, and applying a sheet suction force on the first sheet supporting surface to the second sheet supporting surface. The image recording apparatus according to any one of claims 1 to 6, wherein the sheet suction force is higher than the sheet suction force.

(9) The suction hole is formed in the recess. The plurality of suction holes are formed on the bottom surface of the plurality of recesses. The image recording according to claim 7 or 8, wherein apparatus.

(10) “Recording means is an ink jet head” The image recording means includes a plurality of ink jet heads and moves ink toward the paper while moving in a direction orthogonal to the predetermined direction. The image recording apparatus according to any one of claims 1 to 9, wherein the image is recorded by ejecting the recording medium.

(11) "Position where no recess is formed" The plurality of ink jet heads eject inks having different densities, and the recess is formed by the image recording means in a direction orthogonal to the predetermined direction. A first feature is not formed at a position facing a transport trajectory of an inkjet head that ejects high-density ink when moving.
Item 7. The image recording apparatus according to Item 0.

(12) "Position where no recess is formed (position not corresponding to ink jet head K)" The image recording means includes at least one of the plurality of ink jet heads for ejecting black ink, and 11. The image forming apparatus according to claim 10, wherein when the image recording unit moves in a direction orthogonal to the predetermined direction, the image recording unit is not formed at a position facing a transport trajectory of the inkjet head that ejects the black ink. Image recording device.

(13) "Position where no recess is formed (position not corresponding to ink jet heads K, C and M)" The image recording means is provided with at least black ink, cyan ink and magenta ink among the plurality of ink jet heads. The image recording means moves in a direction perpendicular to the predetermined direction, the inkjet head ejects the black ink, the inkjet head ejects the cyan ink, 11. The image recording apparatus according to claim 10, wherein the recording head is not formed at a position facing each of the transport trajectories of an inkjet head that ejects magenta ink.

(14) “Position for Forming Recess” The recess is provided for the ink jet head located at the most upstream side in the paper transport direction when the image recording means moves in a direction orthogonal to the predetermined direction. 14. The image recording apparatus according to any one of claims 10 to 13, wherein the image recording apparatus is formed further upstream in a sheet transport direction than a position facing the transport path.

(15) “Position for Forming Concave Section” The concave section is a trajectory of an ink jet head for ejecting high-density ink when the image recording means moves in a direction perpendicular to the predetermined direction. 12. The image recording apparatus according to claim 11, wherein the image recording apparatus is formed at a position facing both sides of the transport trajectory in the predetermined direction, without being formed at a position facing the device.

(16) “Position for Forming a Concave Section” The concave section is formed on the transport trajectory of the ink jet head for ejecting the black ink when the image recording means moves in a direction orthogonal to the predetermined direction. 13. The image recording apparatus according to claim 12, wherein the image recording apparatus is not formed at a position facing each other, but is formed at a position facing both sides of the transport trajectory in the predetermined direction.

(17) "Position for Forming Concave Section" The concave section is provided by an ink jet head for ejecting the black ink when the image recording means moves in a direction perpendicular to the predetermined direction, and the cyan ink. Is not formed at a position facing each transport trajectory of the inkjet head that ejects the magenta ink, but is formed at a position facing both sides of the transport trajectory in the predetermined direction. Item 14. The image recording apparatus according to Item 13,

(18) “Comparison of recess shape” The plurality of ink jet heads eject inks having different densities. When the image recording means moves in a direction perpendicular to the predetermined direction, The recess formed at the position facing the transport trajectory of the inkjet head that ejects the low-concentration ink is smaller than the recess formed at the position facing the transport trajectory of the inkjet head that ejects the high-density ink. 11. The image recording apparatus according to claim 10, wherein the image recording apparatus is configured to have a large shape.

(19) "Comparison of Depth of Concave Section" The plurality of ink jet heads eject inks having different densities, and are used when the image recording means moves in a direction orthogonal to the predetermined direction. The recess formed at the position facing the transport trajectory of the inkjet head that ejects the low-density ink is smaller than the recess formed at the position facing the transport trajectory of the inkjet head that ejects the high-density ink. 11. The image recording apparatus according to claim 10, wherein a depth dimension of the image recording apparatus is increased.

[0147]

As is apparent from the above description, according to the image forming apparatus of the present invention, even if the paper floats at both ends of the paper in the direction perpendicular to the transport direction, the paper is supported. Means for preventing the image recording means from being damaged without significantly lowering the image quality, and further, preventing the image recording means and the paper supporting means from supporting the paper. Prevention of paper jam with the front surface can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of a main part of an ink jet printer according to a first embodiment of an image forming apparatus of the present invention.

FIG. 2 is a diagram illustrating a main part of the ink jet printer shown in FIG. 1, in which a platen functioning as a sheet supporting unit is formed by feeding a long sheet to be supplied to the platen into a roll shape; FIG. 4 is a schematic front view showing a transport roller and a discharge roller constituting transport means disposed above and below a platen to pull out long paper from a paper feed roll and transport the long paper along the platen.

3A is a schematic front view of a carriage holding a plurality of inkjet heads functioning as image forming means in a main part of the inkjet printer of FIG. 1; FIG. In the plurality of platen blocks constituting the platen, the platen block disposed at one end in the left-right direction which is a direction orthogonal to the sheet conveyance direction on the platen in FIG. It is a schematic front view which shows a vertical position correspondingly.

FIG. 4A is a view showing a platen block disposed at the center in the left-right direction which is a direction orthogonal to the sheet conveying direction on the platen in FIG. 2 among a plurality of platen blocks constituting the platen in FIG. FIG. 4B is an enlarged front view of FIG. 4B; FIG.
FIG. 3 is a schematic longitudinal sectional view taken along line B.

5 (A) is an enlarged schematic front view of the platen block of FIG. 3 (B); FIG. 5 (B) is a view taken along line BB of the platen block of FIG. 5 (A). 5C is a schematic longitudinal sectional view taken along the line; FIG. 5C is a first sheet supporting surface on the front surface of the platen block of FIG. 5A corresponding to one widthwise end of a sheet conveyed on the front surface; A plurality of recesses corresponding to a length L1 in the paper transport direction including the curved low surface of the plurality of recesses of the paper support surface and an intermediate portion between both ends in the width direction of the paper transported on the front surface. FIG. 9 is a diagram showing a comparison between a straight and flat second sheet supporting surface not including a length L2 in the sheet conveying direction.

FIG. 6A is a diagram illustrating a state in which both ends in the width direction are caused due to residual stress at the time of manufacturing the paper and moisture absorption after the manufacturing, which become apparent when the paper is cut in a predetermined width direction, for example, in a long paper. FIG. 4B is an enlarged perspective view schematically showing a typical shape of a wavy paper floating along the longitudinal direction of the paper generated in FIG.
FIG. 7 is an enlarged front view schematically showing a typical shape of the wavy paper float shown in FIG.

7A is formed on a first sheet supporting surface corresponding to one widthwise end of a sheet conveyed on the front surface on the sheet supporting surface on the front surface of the platen block in FIG. 5A. FIG. 8B is an enlarged schematic front view showing a first modified example of the plurality of recesses; FIG. 7B is a schematic longitudinal sectional view taken along line BB of the platen block in FIG. FIG.

8A is formed on a first sheet supporting surface corresponding to one widthwise end of a sheet conveyed on the front surface on the sheet supporting surface on the front surface of the platen block in FIG. 5A. FIG. 9B is an enlarged schematic front view showing a second modified example of the plurality of recesses; FIG. 8B is a schematic longitudinal sectional view taken along line BB of the platen block in FIG. FIG.

9A is formed on a first sheet supporting surface corresponding to one widthwise end of a sheet conveyed on the front surface on the sheet supporting surface on the front surface of the platen block in FIG. 5A. FIG. 10B is an enlarged schematic front view showing a third modification of the plurality of recesses; FIG. 9B is a schematic longitudinal sectional view of the platen block of FIG. 9A taken along line BB. FIG.

10A is formed on a first sheet supporting surface corresponding to one widthwise end of a sheet conveyed on the front surface on the sheet supporting surface on the front surface of the platen block in FIG. 5A. FIG. 11B is an enlarged schematic front view showing a fourth modified example of the plurality of recesses; FIG. 10B is a schematic longitudinal sectional view taken along line BB of the platen block in FIG. FIG.

11A is formed on a first sheet supporting surface corresponding to one widthwise end of a sheet conveyed on the front surface on the sheet supporting surface on the front surface of the platen block in FIG. 5A. 11B is an enlarged schematic front view showing a fifth modification of the plurality of recesses; FIG. 11B is a schematic vertical cross-sectional view of the platen block of FIG. 11A taken along line BB. FIG.

12A is formed on a first sheet supporting surface corresponding to one widthwise end of a sheet conveyed on the front surface on the sheet supporting surface on the front surface of the platen block in FIG. 5A. FIG. FIG. 13 is an enlarged schematic front view showing a sixth variation of the plurality of recesses; FIG. 12B is a schematic vertical cross-sectional view of the platen block of FIG. FIG.

13A is formed on a first sheet supporting surface corresponding to one widthwise end of a sheet conveyed on the front surface on the sheet supporting surface on the front surface of the platen block in FIG. 5A. FIG. 14B is an enlarged schematic front view showing a seventh modified example of the plurality of recesses; FIG. 13B is a schematic longitudinal sectional view taken along line BB of the platen block in FIG. FIG.

14A is formed on a first sheet supporting surface corresponding to one widthwise end of a sheet conveyed on the front surface on the sheet supporting surface on the front surface of the platen block in FIG. 5A. FIG. FIG. 16B is an enlarged schematic front view showing an eighth modification of the plurality of recesses; FIG. 14B is a schematic vertical cross-sectional view of the platen block of FIG. FIG.

15A is formed on a first sheet supporting surface corresponding to one widthwise end of a sheet conveyed on the front surface on the sheet supporting surface on the front surface of the platen block in FIG. 5A. FIG. 17B is an enlarged schematic front view showing a ninth modification of the plurality of recesses; FIG. 15B is a schematic vertical cross-sectional view of the platen block of FIG. FIG.

FIG. 16 illustrates a plurality of pairs of first paper sheets corresponding to both ends of various width-direction papers when various width-direction papers are used in the paper support portion on the front surface of the platen in FIG. 2;
FIG. 4 is a front view schematically showing various recesses formed on the paper support surface of FIG.

FIG. 17A shows a plurality of recesses formed in a first sheet supporting surface corresponding to one widthwise end of a sheet conveyed on the front side on the sheet supporting surface on the front side of the platen block in FIG. FIG. 18B is an enlarged schematic front view showing a tenth modification of FIG. 17; FIG. 17B is a schematic longitudinal sectional view of the platen block of FIG. 17A taken along line BB.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Paper 18 Transport roller (paper transport means) 20 Transport pinch roller (paper transport means) 22 Front feed roller (paper transport means) 24 Front pinch roller (paper transport means) 30 Rear paper feed roller (paper transport means) 32 Back Pinch roller (paper transport means) 38 Platen (paper support means) 43 Suction fan (suction means) 44a, 44b, 44c, 44d, 44e, 44f, 4
4g recesses 47a, 47b, 47c, 47d, 47e, 47f, 4
7g, 47h recess 48 paper discharge roller (paper transport means) 49a, 49b, 49c, 49d, 49e, 49f, 4
9g recess 50 discharge pinch roller (paper transport means) 51a, 51b, 51c, 51d, 51e, 51f, 5
1g recesses 53a, 53b, 53c, 53d, 53e, 53f, 5
3g recesses 55a, 55b, 55c, 55d, 55e, 55f, 5
5g recess DP0, DP1, DP2, DP3, DP4, DP5 recess K, C, M, LC, LM, Y inkjet head
(Image Forming Means) S1 First paper support surface S2 Second paper support surface WO0, WO1, WO2, WO3, WO4, WO5 Paper width X Paper transport direction Y Paper width direction

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobuyuki Koyama 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Industrial Co., Ltd. (72) Inventor Yasuo Murata 2-43-2 Hatagaya, Shibuya-ku, Tokyo Within Olympus Optical Co., Ltd. (72) Mineo Hashimoto 2-43-2, Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Co., Ltd. Masahiro Nakanishi 2-43-2, Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd. F term (reference) 2C058 AB17 AC07 AD04 AE04 AF31 AF36 AF51 AF54 DA03 DA04 DA11 DA38

Claims (3)

[Claims] An image recording unit configured to record an image on the sheet; and a sheet supporting unit configured to support the sheet at a position facing the image recording unit. In the image recording apparatus, the paper support means is formed corresponding to both ends in the width direction of the paper, and both ends are supported along the predetermined direction; A second sheet support surface formed corresponding to the center, the center being supported along the predetermined direction, and a second length corresponding to the predetermined length of the sheet support means along the predetermined direction. So that the ratio of the length of the paper support surface is greater on the first paper support surface than on the second paper support surface,
An image recording device, which is formed. 2. The image recording apparatus according to claim 1, wherein the first paper support surface has a plurality of recesses arranged apart from each other along the predetermined direction. apparatus. 3. The shape of the recess as viewed from the direction facing the front surface of the paper support means is one selected from a warhead shape, a semicircular shape, a circular shape, an elliptical shape, and a rectangular shape. ,
The image recording apparatus according to claim 2, wherein: