JP2001302060A - Ink jet picture image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a recording face from becoming dirty due to the slide contact of next recording paper on a recording paper discharged on a paper discharge tray previously when a plurality of recording papers are continuously printed irrespective of size of recording paper. SOLUTION: A paper discharge upper roller 10 in which a plurality of star wheels 12 are arranged at an equal interval and a paper discharge lower roller 20 in which a plurality of rollers 22 with rib are arranged at positions deviated in the axial direction for the star wheel 12 are attached in a paper discharge part with such positional relation that allows mutual lapping of an outer peripheral part of the star wheel 12 and an outer peripheral part of the roller 22 with rib when viewed in the axial direction. Moreover, the paper discharge lower roller 20 is moved in the axial direction to adjust a distance 1 between the star wheel 12 and the roller 22 with rib.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge roller provided in the vicinity of a discharge port while forming an image on a sheet-like recording sheet by discharging ink from a recording head and then naturally drying the ink. The present invention relates to an inkjet image forming apparatus that discharges the recording paper by a pair.

[0002]

2. Description of the Related Art In an ink jet type image forming apparatus,
Due to its nature, it takes time to dry the ink after printing, especially when the printing area ratio is large. Therefore, when a special drying device or the like is not mounted, the recording paper may be discharged onto the discharge tray before the ink is completely dried. When continuous printing of a plurality of sheets is performed in such a state, FIG.
As shown in FIG.
There is a problem that the next recording paper P is slid in contact with the upper side, and the printing surface of the recording paper discharged earlier is stained.

For example, Japanese Unexamined Patent Publication No. Hei 6-91861 discloses a method for delaying the time until the next recording sheet slides on the recording sheet discharged on the discharge tray.
On both sides of the paper discharge unit, both side support members that support both sides of the recording paper from the back side are provided. At the center of the paper discharge unit, a press-down unit that presses down the recording paper from the front side is provided. 2. Description of the Related Art An ink jet printer has been proposed in which a sheet is ejected onto a sheet ejection tray while being forcibly biased to a shape.

[0004]

However, in the above-mentioned conventional ink jet printer, since the positions of both side supporting members for supporting both sides of the recording paper are fixed, it is not possible to cope with a small-sized recording paper. there were.

Japanese Patent Laid-Open Publication No. 4-45942 discloses that a recording sheet is passed between a comb-shaped upper discharge roller and a lower discharge roller arranged in a staggered manner in the width direction so that the recording sheet is discharged in the discharge direction. There has been proposed an ink jet recording apparatus which discharges a sheet while forcing it to a waveform when viewed from the viewpoint. However, in this ink jet recording apparatus, a fixing device is installed upstream of the paper discharge section, and it is assumed that the ink is completely dry at the time of paper discharge. It is not intended to delay the time until the next recording paper slides on the recording paper discharged to the paper, but to correct the curl of the recording paper and prevent the loadability on the paper output tray from lowering. belongs to. Further, in the above-described ink jet recording apparatus, since it is assumed that the ink is dry at the time of paper ejection as described above, a roller which presses the recording surface of the recording paper in a planar manner is used as the paper ejection upper roller. However, if such a paper discharge upper roller is mounted on a naturally drying type ink jet recording apparatus having no fixing device or the like, the recording surface may be rubbed by the paper discharge upper roller and become dirty.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to discharge paper onto a paper discharge tray first during continuous printing of a plurality of sheets regardless of the size of recording paper. An object of the present invention is to provide an ink jet image forming apparatus capable of preventing a recording surface from being stained due to the next recording paper slidingly contacting a completed recording paper.

[0007]

In order to achieve the above object, the present invention provides a method of forming an image on a recording sheet by ejecting ink from a recording head, and then drying the ink while discharging the ink in the vicinity of a discharge port. In the inkjet image forming apparatus for discharging the recording paper by a discharge roller pair provided in the printer, the discharge roller pair is mounted on the recording surface side of the recording paper, and a plurality of star wheels are disposed in the axial direction. A discharge upper roller, and a lower discharge roller, in which a plurality of ribbed rollers are axially offset from a plurality of star wheels of the upper discharge roller,
The upper discharge roller and the lower discharge roller are mounted in a positional relationship such that an outer peripheral portion of the star wheel and an outer peripheral portion of the ribbed roller overlap each other when viewed in the axial direction. This is configured as an inkjet image forming apparatus that performs the above-described operations.

With such a configuration, the recording paper is curved in a waveform as viewed in the paper discharge direction when passing between the upper discharge roller and the lower discharge roller. Does not hang down, so that the recording surface can be prevented from being stained due to the leading edge of the next recording sheet rubbing on the recording sheet previously discharged onto the discharge tray. In addition, since a star wheel is used for the upper discharge roller, the recording surface of the recording paper is point-pressed by the star wheel.
The recording surface is not stained by rubbing with the rollers. Further, since the star wheel and the ribbed roller are mounted in a plurality of sets in the axial direction, the recording paper can be surely curved into a waveform regardless of the paper size, and can be adapted to a small-sized recording paper. .

Further, if an axial distance adjusting means for changing the axial distance between the corresponding star wheel and the ribbed roller is provided, the degree of curvature of the waveform of the recording paper can be determined, for example, by the size of the recording paper (discharge size). Since the adjustment can be made according to the length in the paper direction) and the thickness, the above-described effects can be reliably achieved regardless of the type of recording paper. The axial distance adjusting means may change the relative position of the upper discharge roller in the axial direction with respect to the lower discharge roller, for example.
One of the lower rollers can be moved in the axial direction,
Alternatively, it can be realized by making any one of the star wheel and the ribbed roller slidable with respect to its rotation axis. However, in this case, it is desirable to make the roller on the paper discharge upper side having the star wheel movable, since it is mechanically simpler to make the roller on which the drive is not performed movable.

[0010] The size of the recording paper (length in the paper discharging direction)
The larger the is, the longer the cantilever is supported until the sheet is completely discharged, so that it is necessary to further increase the curvature of the waveform in order to prevent the tip from sagging. Therefore, the larger the size of the recording paper, the smaller the axial distance between the star wheel and the ribbed roller by the axial distance adjusting means, so that the curvature of the waveform can be increased. It is possible to prevent the leading end of the recording paper from hanging down when the recording paper is discharged.

The axial distance between the star wheel and the ribbed roller can be adjusted manually. However, the axial distance adjustment means includes a size detecting means for detecting the size of the recording paper. By automatically changing the axial distance between the star wheel and the ribbed roller based on the detection result of the size detecting means, the effect of preventing the leading end of the recording paper from sagging is more reliable. It becomes something. Here, as the size detecting means, for example, a means for detecting the size of the recording paper based on the position of a movable regulating member for regulating the width direction of the recording paper, and a plurality of widths provided in the width direction of the recording paper A detection unit that detects the size of the recording paper based on the detection result of the direction end detection sensor, or the recording paper based on a detection result of a paper cassette detection unit that detects a type of a paper cassette that stores the recording paper. One that can detect the size of an image is conceivable.

Further, the thinner the recording paper, the weaker the stiffness. Therefore, in order to prevent the tip of the recording paper from sagging, it is necessary to increase the curvature of the waveform. Therefore, as the thickness of the recording paper is smaller, the axial distance between the star wheel and the ribbed roller is reduced by the axial distance adjusting means, whereby the waveform can be more strongly curved. It is possible to prevent the leading end of the recording paper having such a thickness from sagging at the time of discharge. Also in this case, the adjustment of the axial distance between the star wheel and the ribbed roller can be performed manually, but it is provided with a thickness detecting means for detecting the thickness of the recording paper, and The distance adjusting means automatically changes the axial distance between the star wheel and the ribbed roller based on the detection result of the thickness detecting means, thereby preventing the leading end of the recording paper from sagging. The effect is more certain.

Further, if the curvature of the recording paper by the pair of paper discharge rollers is transmitted to a position facing the recording head on the upstream side of the recording paper, the recording paper is hindered in order to hinder image formation. It is desirable to provide a flat surface holding means.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments and examples of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention. The following embodiments and examples are examples embodying the present invention, and do not limit the technical scope of the present invention.

(First Embodiment) First, a schematic configuration of an ink jet image forming apparatus Z1 according to a first embodiment will be described with reference to FIG. 1 and other drawings. In the inkjet image forming apparatus Z1, the recording paper P is placed on the paper feed cassette 1. When a print request based on image information from a computer or the like (not shown) is issued to the image forming apparatus Z1, one recording sheet P is pulled out from the sheet cassette 1 by the pickup roller 2 having a half-moon cross section. The recording paper P pulled out by the pickup roller 2 is transported by the transport roller 3 while being inverted upward as indicated by an arrow Y1, and further transported along the surface of the platen 5 by the transport roller pair 4.

A recording head 6 is provided above the platen 5 so as to face the platen 5. The recording head 6 is capable of reciprocating in a main scanning direction (a direction perpendicular to the plane of FIG. 1) perpendicular to the direction in which the recording paper P is conveyed. The recording paper P is intermittently moved along the platen 5 by the ink ejection width of the recording head 6 (arrow Y).
2). At this time, while the recording paper P is stopped, the recording head 6 moves in the main scanning direction while discharging ink, and forms an image corresponding to the width of the recording head 6 on the recording paper P. I do. By repeating this operation, an image corresponding to the image information is continuously formed on the recording paper P. Recording paper P on which an image has been formed on platen 5
Is discharged onto a paper discharge tray 30 by a paper discharge upper roller 10 and a paper discharge lower roller 20 provided on the downstream side of the platen 5.

Here, the configuration of the upper discharge roller 10 and the lower discharge roller 20, which are features of the first embodiment, will be described in detail. As shown in FIG. 2, the upper discharge roller 10 includes a rotating shaft 11 rotatably mounted on the side plate 40 and a plurality of star wheels 12 mounted on the rotating shaft 11 at equal intervals. ing. The upper discharge roller 10 is a driven roller that rotates in accordance with the rotation of the lower discharge roller. As shown in FIG. 2, the lower discharge roller 20 has a rotating shaft 21 rotatably and axially movable with respect to the side plate 40, and the same as the star wheel 12 on the rotating shaft 21. And a plurality of ribbed rollers 22 attached at intervals. The lower discharge roller 20 is a drive roller connected to a drive motor (not shown). Here, the ribbed rollers 22 are respectively mounted at positions shifted in the axial direction with respect to the star wheel 12, and the upper discharge roller 10 and the lower discharge roller 20 are connected to the star wheel 12. And the outer peripheral portion of the ribbed roller 22 are attached in a positional relationship such that they overlap each other when viewed in the axial direction.

As a result, when the recording paper P passes between the upper discharge roller 10 and the lower discharge roller 20, the recording paper P is curved in a waveform when viewed in the discharge direction (see FIG. 3). As shown in FIG. 1, the leading end of the recording sheet P does not hang down at the time of discharge, and therefore, the leading end of the next recording sheet P rubs on the recording sheet P discharged onto the discharge tray 30 first. Can prevent the recording surface from being stained. Further, since the star wheel 12 is used for the upper discharge roller 10, the recording surface of the recording paper P is point-pressed by the star wheel 12, and the recording surface is not stained by rubbing with the roller. Further, since a plurality of sets of the star wheel 12 and the ribbed rollers 22 are attached to the upper discharge roller 10 and the lower discharge roller 20 at equal intervals, it is possible to surely bend the waveform into a waveform regardless of the paper size. It can also handle small-sized recording paper.

In the image forming apparatus Z1, the rotating shaft 21 of the lower discharge roller 20 is moved in the axial direction, so that the ribbed roller 22 and the star wheel 12 are moved.
Can be varied in the range of l ₁ to l ₂ (where l ₁ > l ₂ ) (see FIG. 3). In addition, the lower paper discharge roller 20 is moved by a spring member (not shown) in the direction of increasing the distance l (the end 21a of the rotating shaft 21).
(FIG. 2) is elastically biased in the direction in which it protrudes from the side plate 40). Further, as shown in FIG. 2, a plate-shaped rotating member 41 in which a tapered surface 41a and a lever 41b are integrally formed is attached to the side plate 40. When the rotating member 41 is rotated counterclockwise by operating the lever 41b, the tapered surface 41a axially presses the rotating shaft end 21a of the discharge lower roller 20, and the ribbed roller 22 Star wheel 12
Is gradually reduced from the maximum l ₁ (see FIG. 3).
(A) → (b)). From that state, on the contrary, the rotating member 4
When 1 is rotated clockwise, the pressing of the rotating shaft end 21a by the tapered surface 41a is relaxed, and the distance l gradually increases (FIG. 3 (b) → (a)). Thus, by adjusting the amount of rotation of the rotating member 41, the distance l between the ribbed roller 22 and the star wheel 12 can be adjusted to an appropriate value between l ₁ and l _2. is there. Note that the lower discharge roller 2 is movable in the axial direction.
0, an example of the axial distance adjusting means is constituted by the rotating member 41 and the like.

Here, as shown in FIG. 3, when the distance l between the ribbed roller 22 and the star wheel 12 is long (FIG. 3 (a)), the curved shape of the waveform of the recording paper P becomes gentle. When the distance 1 is short (FIG. 3B), the curved shape of the recording paper P becomes tight. Therefore, the recording paper P
When the size (length in the conveying direction) of the recording paper P is large or when the paper thickness is small (the waist is weak), the size of the recording paper P is reduced in a direction in which the distance l between the ribbed roller 22 and the star wheel 12 is reduced. When the recording paper P is small, or when the paper thickness is thick (the waist is strong), the amount of rotation of the rotating member 41 is adjusted in the direction of increasing the distance l so that the recording paper P is always discharged regardless of the type. It is possible to prevent the leading end of the paper from sagging at the time of paper and prevent the recording surface of the recording paper P on the discharge tray 30 from being stained.

In the above example, the lower discharge roller 20 is moved to change the distance l between the ribbed roller 22 and the star wheel 12, but the upper discharge roller 10 is moved. Is also good. Of course, both may be movable. In many cases, the mechanism is considered to be simpler when the driven upper discharge roller 10 is moved.

As described above, in the ink jet image forming apparatus Z1 according to the first embodiment, the upper paper discharge roller 10 provided with the plurality of star wheels 12 and the plurality of ribbed rollers 22 are provided. A discharge roller pair is constituted by the discharge lower roller 20, and the discharge upper roller 10 and the discharge lower roller 20 face each other in a state where the ribbed roller 22 and the star wheel 12 are shifted from each other in the axial direction. Further, since the outer peripheral portions of the recording paper P are mounted so as to overlap with each other when viewed in the axial direction, the recording paper P is moved when passing between the upper discharge roller 10 and the lower discharge roller 20. It is curved in a waveform when viewed in the paper discharge direction. Therefore, the leading end of the recording sheet P does not hang down during ejection, and the leading end of the next recording sheet P rubs on the recording sheet P ejected onto the ejection tray 30 earlier. Dirt can be prevented.

Since the star wheel 12 is used for the upper discharge roller 10, the recording surface side of the recording paper P is point-pressed by the star wheel 12, and the recording surface may become dirty due to friction with the roller. Absent. Further, since a plurality of sets of the star wheel 12 and the ribbed rollers 22 are attached at equal intervals in the paper width direction, the recording paper can be surely curved into a waveform regardless of the paper size. It can also handle recording paper.
Further, the star wheel 12 and the ribbed roller 2
Since the distance l from the rotating member 2 can be adjusted by the amount of rotation of the rotating member 41, if the amount of rotation of the rotating member 41 is adjusted according to the size and thickness of the recording sheet P, for example, the type of the recording sheet P can be adjusted. Regardless of this, it is possible to always prevent the leading end of the sheet from sagging when the sheet is discharged, and prevent the recording surface of the recording sheet P on the discharge tray 30 from being stained.

(Other Embodiments) First Embodiment
Now, the star wheel 12 and the ribbed roller 2
Although the example has been described in which the user moves the lower paper discharge roller 20 (or the upper paper discharge roller 10) in the axial direction manually to adjust the distance 1 to the recording paper P, It is also possible to carry out automatically in response. For example, a drive motor for rotating the rotating member 41 (FIG. 2) and size detection means for detecting the size of the recording paper P are provided, and drive control of the drive motor is performed based on the detection result from the size detection means. It is possible to do. FIG. 4 shows an example of such a configuration. The position of a movable regulating member 53 that regulates the width direction of the recording paper P is detected by a sensor 52 (an example of a size detecting unit), and a drive motor 51 that drives a rotating member 41 (FIG. 2) is detected by the sensor 52. It is configured to perform control based on

As the size detecting means for detecting the size of the recording paper P, various types can be considered other than the sensor 52 for detecting the position of the movable regulating member 53 as shown in FIG. For example, as shown in FIG. 5, a plurality of sensors 54 for detecting the presence or absence of the recording paper P are arranged in the width direction of the recording paper P, and the size of the recording paper P is detected based on the detection signals. Is also good. When a different paper cassette is used for each paper size, as shown in FIG. 6, a different detected part 1a (for example, a different number of protrusions) is provided for each paper cassette 1 and the detected part 1a is provided. Is detected by the detection unit 55 to determine the size of the recording paper P.

As means for moving the lower discharge roller 20 (or upper discharge roller 10) in the axial direction according to the size of the recording paper P, in addition to using a sensor and a drive motor as described above, a link or the like may be used. It is also possible to realize only with the simple mechanism described above. In the example shown in FIG.
Restricting member 53 and discharge lower roller 2 for restricting the width direction of sheet
0 is connected to the rotating shaft 21 by a link arm 56, and the lower discharge roller 20 is moved in accordance with the amount of movement of the movable regulating member 53.
Are configured to move in the axial direction. By using such a simple mechanism, the cost of the apparatus can be reduced.

In the above example, the distance l between the star wheel 12 and the ribbed roller 22 is adjusted according to the size of the recording paper P. However, the distance l is adjusted according to the thickness of the recording paper P. The distance l may be adjusted. In this case, the thickness of the recording paper P
Can be detected by measuring the distance between the shafts of the transport rollers when passing through. Of course, other known techniques may be used.

In the above example, the star wheel 12
To adjust the distance 1 between the ribbed roller 22 and
The ribbed roller 22 (or the star wheel 12) is configured to be moved together with the rotating shaft 21 (or the rotating shaft 11). For example, the rotating shaft 21 and the like are fixed in the axial direction, and the ribbed roller 22 is rotated. It is also possible to adjust the distance 1 between the star wheel 12 and the ribbed roller 22 by sliding with respect to the shaft 21.

In the image forming apparatus Z1 shown in FIG.
The recording paper P is conveyed to the opposing portion of the recording head 6 in a state in which the recording paper P is curved along the conveying roller 3, so that a strong force acts to maintain a flat state at the opposing portion with the recording head 6. . Therefore, if the recording head 6 is mounted at a position sufficiently close to the transport roller 3, even if the recording paper P is curved in the waveform as described above in the downstream paper discharge section, the curvature is not affected by the recording. It does not travel to the portion facing the head 6 and does not hinder image formation. However, if there is a possibility that the curvature in the downstream paper discharge section may be transmitted to the print head facing section, for example, when the distance between the print head 6 and the transport roller 3 is large, the above-mentioned area near the print head facing section is used. It is desirable to mount a plane holding means for holding the recording paper P on a plane. As the flat surface holding means, for example, a configuration including a roller for pressing the recording paper P against the platen 5 on the downstream side of the recording head 6 can be considered.

[0030]

As described above, according to the present invention, after an image is formed on a recording paper by discharging ink from a recording head, the ink is naturally dried, and the paper discharge provided near the paper discharge port is formed. In an inkjet image forming apparatus for discharging the recording paper by a roller pair, the discharge roller pair is attached to a recording surface side of the recording paper,
An upper discharge roller having a plurality of star wheels disposed axially, and a lower discharge roller having a plurality of ribbed rollers disposed axially offset with respect to the plurality of star wheels of the upper discharge roller. The upper discharge roller and the lower discharge roller are mounted in a positional relationship such that the outer peripheral portion of the star wheel and the outer peripheral portion of the ribbed roller overlap each other when viewed in the axial direction. When the recording paper passes between the upper discharge roller and the lower discharge roller, the recording paper is curved in a waveform as viewed in the discharge direction when the recording sheet passes between the upper discharge roller and the lower discharge roller. The leading end of the next recording sheet does not hang down when the sheet is fed, so that the recording surface can be prevented from being stained by the leading end of the next recording sheet rubbing on the recording sheet previously ejected onto the sheet ejection tray. In addition, since a star wheel is used for the upper discharge roller, the recording surface side of the recording paper is pressed pointwise by the star wheel, and the recording surface is not stained by friction with the roller. Further, since the star wheel and the ribbed roller are mounted in a plurality of sets in the axial direction, the recording paper can be surely curved into a waveform regardless of the paper size, and can be adapted to a small-sized recording paper. .

Further, if an axial distance adjusting means for changing the axial distance between the corresponding star wheel and the ribbed roller is provided, the degree of curvature of the recording paper waveform can be determined, for example, by the size of the recording paper (discharged paper). Since the adjustment can be made according to the length in the paper direction) and the thickness, the above-described effects can be reliably achieved regardless of the type of recording paper. The axial distance adjusting means may change the relative position of the upper discharge roller in the axial direction with respect to the lower discharge roller, for example.
One of the lower rollers can be moved in the axial direction,
Alternatively, it can be realized by making any one of the star wheel and the ribbed roller slidable with respect to its rotation axis. However, in this case, it is desirable to make the roller on the paper discharge upper side having the star wheel movable, since it is mechanically simpler to make the roller on which the drive is not performed movable.

The size of the recording paper (length in the paper discharge direction)
The larger the is, the longer the cantilever is supported until the sheet is completely discharged, so that it is necessary to further increase the curvature of the waveform in order to prevent the tip from sagging. Therefore, the larger the size of the recording paper, the smaller the axial distance between the star wheel and the ribbed roller by the axial distance adjusting means, so that the curvature of the waveform can be increased. It is possible to prevent the leading end of the recording paper from hanging down when the recording paper is discharged.

The axial distance between the star wheel and the ribbed roller can be adjusted manually. However, the axial distance adjusting means includes a size detecting means for detecting the size of the recording paper. By automatically changing the axial distance between the star wheel and the ribbed roller based on the detection result of the size detecting means, the effect of preventing the leading end of the recording paper from sagging is more reliable. It becomes something. Here, as the size detecting means, for example, a means for detecting the size of the recording paper based on the position of a movable regulating member for regulating the width direction of the recording paper, and a plurality of widths provided in the width direction of the recording paper A detection unit that detects the size of the recording paper based on the detection result of the direction end detection sensor, or the recording paper based on a detection result of a paper cassette detection unit that detects a type of a paper cassette that stores the recording paper. One that can detect the size of an image is conceivable.

The thinner the recording paper, the weaker the stiffness. Therefore, in order to prevent the leading end from sagging, it is necessary to increase the curvature of the waveform. Therefore, as the thickness of the recording paper is smaller, the axial distance between the star wheel and the ribbed roller is reduced by the axial distance adjusting means, whereby the waveform can be more strongly curved. It is possible to prevent the leading end of the recording paper having such a thickness from sagging at the time of discharge. Also in this case, the adjustment of the axial distance between the star wheel and the ribbed roller can be performed manually, but it is provided with a thickness detecting means for detecting the thickness of the recording paper, and The distance adjusting means automatically changes the axial distance between the star wheel and the ribbed roller based on the detection result of the thickness detecting means, thereby preventing the leading end of the recording paper from sagging. The effect is more certain.

Further, if the curvature of the recording paper by the pair of paper ejection rollers is transmitted to a position facing the recording head on the upstream side thereof, it will hinder image formation. Therefore, the recording paper is held flat in the vicinity of the recording head. It is desirable to provide a flat surface holding means.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall schematic configuration of an inkjet image forming apparatus Z1 according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a paper discharge upper roller 10, a paper discharge lower roller 20, and the periphery thereof, which are characteristic parts of the inkjet image forming apparatus Z1.

FIG. 3 is an explanatory diagram showing a difference in a curved state of a recording sheet P when a distance 1 between a star wheel 12 and a ribbed roller 22 is changed.

FIG. 4 is a diagram showing an example of a configuration in which a distance 1 between a star wheel 12 and a ribbed roller 22 is automatically changed based on a detection result of a size detection unit that detects the size of a recording sheet P.

FIG. 5 is a diagram showing another example of the size detecting means.

FIG. 6 is a diagram showing another example of the size detecting means.

FIG. 7 is a diagram showing an example of a configuration in which a distance 1 between a star wheel 12 and a ribbed roller 22 is automatically changed according to the size of a recording sheet P.

FIG. 8 is a diagram showing an overall schematic configuration of a conventional inkjet image forming apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Paper feed cassette 1a ... Detected part 5 ... Platen 6 ... Recording head 10 ... Discharge upper roller 11 ... Rotating shaft 12 ... Starwheel 20 ... Discharge lower roller (constituting an example of an axial distance adjusting means) 21 ... Rotation Shaft 22 ... Ribbed roller 41 ... Rotating member (an example of an axial distance adjusting means) 51 ... Drive motor 52 ... Sensor (an example of a size detection sensor) 53 ... Movable regulating member 54 ... Sensor (an example of a size detection sensor) 55 ... Detector (an example of a size detection sensor) 56 ... Link arm (an example of an axial distance adjusting means)

Continued on the front page (72) Inventor Masanori Yamada 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka F-term (reference) 2C056 EB13 EB46 HA28 HA34 2C059 BB07 BB10 BB12 BB22 3F049 AA10 CA03 CA23 DA11 LA01 LB03 3F053 HA07 HB03 LA01 LB03

Claims (12)

[Claims] An image is formed on a recording sheet by discharging ink from a recording head, and the recording sheet is discharged by a pair of discharge rollers provided near a discharge port while the ink is naturally dried. In the ink jet image forming apparatus, the discharge roller pair is mounted on the recording surface of the recording paper, and a plurality of star wheels are disposed in the axial direction. A lower discharge roller disposed at a position axially displaced from the plurality of star wheels of the roller,
The upper discharge roller and the lower discharge roller are mounted in a positional relationship such that an outer peripheral portion of the star wheel and an outer peripheral portion of the ribbed roller overlap each other when viewed in the axial direction. Inkjet image forming apparatus. 2. The ink jet image forming apparatus according to claim 1, further comprising an axial distance adjusting means for changing an axial distance between the star wheel and the ribbed roller. 3. The ink-jet image forming apparatus according to claim 2, wherein said axial distance adjusting means changes an axial relative position of said upper discharge roller with respect to said lower discharge roller. 4. The ink jet image forming apparatus according to claim 3, wherein said axial distance adjusting means is configured to change an axial position of said upper discharge roller. 5. The axial distance between said star wheel and said ribbed roller is reduced by said axial distance adjusting means as the size of said recording paper increases.
5. The inkjet image forming apparatus according to any one of items 1 to 4, 6. A size detecting means for detecting a size of the recording sheet, wherein the axial distance adjusting means determines an axial direction of the star wheel and the ribbed roller based on a detection result by the size detecting means. 6. The ink jet image forming apparatus according to claim 5, wherein the distance is automatically changed. 7. An ink jet image forming apparatus according to claim 6, wherein said size detecting means detects the size of said recording paper based on a position of a movable regulating member which regulates a width direction of said recording paper. 8. The recording sheet according to claim 6, wherein the size detecting means detects the size of the recording sheet based on the detection results of a plurality of width direction edge detection sensors provided in the width direction of the recording sheet.
The inkjet image forming apparatus as described in the above. 9. The ink jet recording apparatus according to claim 6, wherein said size detecting means detects the size of the recording paper based on a detection result of a paper feeding cassette detecting means for detecting a type of a paper feeding cassette accommodating the recording paper. Image forming device. 10. The axial distance between the star wheel and the ribbed roller by the axial distance adjusting means, as the thickness of the recording paper decreases.
5. The inkjet image forming apparatus according to any one of 4. 11. A thickness detecting means for detecting a thickness of the recording paper, wherein the axial distance adjusting means is configured to control the star wheel, the ribbed roller and the rib based on a detection result by the thickness detecting means. The inkjet image forming apparatus according to claim 10, wherein the axial distance is automatically changed. 12. The ink-jet image forming apparatus according to claim 1, further comprising a plane holding means for holding said recording sheet on a plane near said recording head.