JP2001287848A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a trouble caused by a bend of a flap part of a long shaped envelope. SOLUTION: This device includes a sheet loading means 105 loading sheets, a sheet feeding means 106 feeding sheets loaded on the sheet loading device 105 one by one, image forming means 102a, 102b, 102c, 102d forming images on the sheets, sheet conveying means 107, 108, 109, 110a, 110b, 110c, 110d, 110e conveying sheets fed by the sheet feeding means 106 at least to the image forming means. The sheet conveying means convey sheets to the image forming means 102a, 102b, 102c, 102d in a manner that a part of a sheet fed later overlaps a sheet fed earlier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming an image on a cut sheet, and more particularly to an image forming apparatus suitable for continuously transporting a long envelope as a sheet.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a printer, a sheet stacking section provided with a stacking tray or a stacking cassette for stacking cut sheet materials (hereinafter simply referred to as sheets), and a sheet stacking section. A sheet feeding unit such as a feeding roller for sequentially feeding the stacked sheets one by one;
An image forming unit such as a print head for forming an image on a sheet,
The image forming apparatus includes a sheet conveying unit that conveys the sheet fed by the sheet feeding unit along a print head and the like, a sheet discharging unit that discharges an image-formed sheet outside the apparatus, and the like.

In the image forming apparatus, when continuously forming images on a plurality of sheets, in order to continuously supply the plurality of sheets to the image forming unit, the plurality of sheets are stacked on the sheet stacking unit in advance. Each sheet is sequentially fed one by one at predetermined intervals by a feed roller or the like of a sheet feeding unit, and is conveyed to an image forming unit by a sheet conveying unit.

Hereinafter, timing control of sheet conveyance when the image forming section is an image forming apparatus of an ink jet system will be described. In this case, the sheet supplied to the image forming unit is conveyed by the sheet conveying unit below the image forming unit (print head unit) for discharging ink, and the ink discharged from the print head unit lands. The sheet is conveyed to the sheet discharge unit by the sheet conveyance unit while the ink is landed as needed by the print head unit, and is discharged outside the machine.

Here, in the case of forming an image continuously on a plurality of sheets, for example, after the first sheet passes under the print head and this passage is detected by a sensor or the like, the second sheet is formed. Sheets are fed or the second sheet is conveyed under the print head when the first sheet passes under the print head. Is fed, and in the image forming apparatus,
Conventionally, an image is continuously formed on a plurality of sheets by repeating such an operation.

Here, when an image is formed on a sheet, in order to surely land ink at a predetermined position on the sheet,
In order to recognize the timing of starting ink ejection, it is necessary to detect the position of the leading edge of the conveyed sheet.

When the image to be printed is longer than the length of the sheet in the feed direction, if ink is ejected when there is no sheet below the print head, the ink is ejected to the sheet transport section. And the sheet conveyance section becomes dirty, or the image to be formed on the previous sheet is formed on the next sheet, so that in order to avoid this, one sheet It is necessary to detect the position of the trailing end of the sheet and to surely end the ejection of the image based on one image data with the length of one sheet.

As described above, in the image forming apparatus, it is necessary to detect the leading edge and the trailing edge of the conveyed sheet in the feeding direction in order to surely form the image one sheet at a time.

Under such a premise, in a conventional image forming apparatus, in order to detect the leading edge and the trailing edge of one sheet, a plurality of images are continuously fed to each of the sequentially conveyed sheets. In the case of forming a sheet, it is necessary to leave at least a predetermined interval between a sheet conveyed earlier and a sheet conveyed later, and a sheet conveyed later is compared with a sheet conveyed earlier. Were not able to catch up and overlap.

[0010]

However, in recent years,
As a sheet on which an image is formed by an image forming apparatus, various types of sheets, such as envelopes, postcards, plastic films, and cardboard, have been used as well as ordinary fixed-size paper and special paper. However, the conventional image forming apparatus has the following problems.

For example, in a conventional ink jet type image forming apparatus, a gap between a conveyed sheet and a print head is narrow, and therefore, the sheet warps toward the print head or the sheet floats. In some cases, for example, the sheet touches the print head, causing problems such as image failure, conveyance failure, and print head failure.

Conventionally, in order to solve such a problem, the sheet is conveyed while being pressed by rollers or the like on the front and rear sides or the left and right sides with respect to the sheet conveyance direction, or the sheet is held only before and after the print head. In addition, measures have been taken to prevent the floating of the sheet by using the stiffness of the sheet by bending the conveying path through which the sheet is conveyed.

However, an image forming apparatus in which a sheet cannot be conveyed while being sandwiched between rollers and the like, for example, an image forming apparatus having an image forming section for forming an image on the entire surface of the sheet, or a sheet perpendicular to the sheet conveying direction If the movement width of the print head is longer than the length in the sheet width direction, it is very difficult to completely suppress the sheet warpage immediately below the print head.

In particular, when an image is formed by transporting a long envelope as a sheet, the structure of the envelope is a bag-like shape, and the main part of the envelope is overlapped with the sheet and has a thickness.
Since the end portion to be sealed has such a shape that one sheet is thin with one sheet (hereinafter, referred to as “flap portion”),
The following problems have occurred.

That is, when printing a long envelope with the image forming apparatus, the portion (flap portion) of one sheet is likely to be warped, so that the sheet is stacked on the sheet stacking portion and the sheet feeding portion and the sheet conveying portion. In the case where the paper is fed, the flap portion comes into contact with the print head, and a defective image is likely to occur.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problem caused by contact with the image forming section due to the warpage of the rear end of the sheet, and particularly to prevent the problem caused by the warp of the flap portion in a long envelope. It is an object of the present invention to provide an image forming apparatus capable of performing the following.

[0017]

The main components of the image forming apparatus according to the present invention include sheet stacking means for stacking sheets, sheet feeding means for sequentially feeding sheets stacked on the sheet stacking means, and sheet feeding means. An image forming unit that forms an image on the sheet, and a sheet conveying unit that conveys a sheet fed by the sheet feeding unit to at least the image forming unit. Then, the sheet fed later is conveyed to the image forming means so that a part of the sheet is overlapped.

[0018]

Embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment] First, the first embodiment of the present invention will be described.
The embodiment will be described with reference to FIGS. FIG. 1 is a schematic sectional view showing a schematic configuration of an image forming apparatus to which the present invention is applied.

This image forming apparatus has a configuration in which an image forming apparatus main body 101 in which an image forming means is arranged and a sheet feeding section 103 for feeding a sheet to the image forming means are connected.

Here, the sheet feeding section 103 includes a sheet stacking section 105 for stacking sheets, and a sheet stacking section 105.
A feeding roller 106, a pair of separation rollers 107, and a skew feeding correction roller 108 for feeding the sheets stacked on the image forming apparatus main body 101 are disposed.

The sheet stacking section 105 includes the sheet feeding section 10
3, a sheet stacking tray 105a and a sheet stacking tray 105a configured to be vertically movable with respect to the wall 105c.
A tray detection sensor 105b for detecting the height of the sheet stacking tray 105, and a tray driving unit (not shown) for adjusting the height of the sheet stacking tray 105a based on the output of the tray detection sensor 105b, as shown in FIG. A large amount of sheets can be stacked on the sheet stacking tray 105a. Further, in the sheet stacking unit 105, a long envelope can be used as a sheet to be stacked on the sheet stacking unit 105. The details of the long envelope and the operation when the long envelope is stacked will be described later. .

The feeding roller 106 is movable in the vertical direction in FIG. 1 so that, when feeding a sheet, it comes into contact with the highest one of the sheets 104 stacked on the sheet stacking section 105. The sheet is moved and rotated in the counterclockwise direction in FIG. 1 to feed the uppermost sheet in the direction of the separation roller 107.

The upper pair of separation rollers 107a are driven to rotate counterclockwise in FIG.
And a lower retard roller 107b opposite to the feed roller 107a and to which a driving torque is applied in a counterclockwise direction in FIG. In this embodiment, the upper delivery roller 107a is movable in the vertical direction, and is pressed against the lower retard roller 107b by the urging force of a spring (not shown).

The separation roller pair 107 includes the delivery roller 1
In a state where there is no sheet in the nip portion between the sheet roller 07a and the retard roller 107b, and in a state where only one sheet is fed by the feed roller 106 and fed into the nip portion, the retard roller 107b is moved out of the feed roller 107a.
, The sheet is conveyed in the direction of the skew correction roller 108.

On the other hand, when a plurality of sheets are fed by the feed roller 106 and a plurality of sheets are fed to the nip portion between the feed roller 107a and the retard roller 107b, the retard roller 107b
The roller is rotated counterclockwise in FIG. 1 by the driving torque of FIG.
05, and only the uppermost sheet is
8 is conveyed.

The skew correction roller 108 includes a separation roller pair 1
One sheet sent from 07 is sent to the image forming apparatus main body 101 while correcting skew. Here, the skew correction roller 108 has a skew feeding mechanism (not shown) that can skew the sheet so that the sheet fed to the image forming apparatus main body 101 is straight. ing.

On the other hand, in the image forming apparatus main body 101, as image forming means for forming an image on a sheet, a plurality (four in this embodiment) for ejecting ink on the sheet is provided.
Print heads 102a, 102b, 102c, 102d
Constitute the inkjet discharge units 102 arranged in the sheet conveying direction. This inkjet discharge unit 10
No. 2 is such that each of the print heads 102a to 102d ejects ink of a different color to form an image on a sheet by a full-color ink jet method.

In the image forming apparatus main body 101, there is provided a sheet conveying section 109 for conveying the sheet sent from the skew feeding correcting roller 108 of the sheet feeding section 103. The sheet conveying unit 109 includes the skew correction roller 10.
8 is sent to the inkjet discharge unit 1
02, and is discharged and stacked on a sheet discharge tray (not shown) arranged outside the image forming apparatus main body 101. Specifically, each print head 102a to 102d is conveyed along the position of each print head 102a to 102d. A transport belt 109a disposed along the positions of the print heads 102a to 102d, and an upstream drive pulley 109b, a downstream driven pulley 109c, and a drive pulley 109b for driving the transport belt 109a rotatably spanning the transport belt 109a. Roller 109 which comes into pressure contact with the drive motor, the drive pulley 109b and the transport belt 109a.
d, each print head 102a
A plurality of spurs 110a arranged at positions between -102d
To 110e. The roller 109d and the spurs 110a to 110e are pressed downward in FIG. 1 by a spring (not shown) so as to be pressed against the transport belt 109a.

In the sheet conveying section 109, a driving motor (not shown) rotates the driving pulley 109b clockwise in FIG.
9a is driven to rotate in the same direction, and the sheet sent from the skew feeding correction roller 108 is conveyed while being pinched by the conveying belt 109a and the rollers 109d and spurs 110a to 110e pressed against the conveying belt 109a. The sheet is conveyed to the outside of the image forming apparatus main body 101 while preventing the occurrence of warpage or floating.

An image forming apparatus main body 101 having such an ink jet discharging section 102 and a sheet conveying section 109
Then, the sheet sent from the skew correction roller 108 of the sheet feeding unit 103 is conveyed while being nipped by the conveyance belt 109a, the rollers 109d and the spurs 110a to 110e pressed against the conveyance belt 109a, and the print heads 102a to
An image is formed while each color ink is ejected on the upper surface of the sheet by 102d, and is discharged and stacked on the sheet discharge tray.

Next, the detailed configuration and operation of the sheet transfer section for transferring sheets from the sheet feeding section 103 to the image forming apparatus 101 will be described with reference to FIG.

As shown in FIG. 2A, a guide member 107c for guiding the conveyance of the sheet is provided at the sheet delivery portion.
108c, sheet detection sensors 202 and 203 for detecting the passage of the sheet, and a guide plate 201 are arranged.
Here, the height position of the nip portion of the skew feeding correction roller 108 is disposed below the height position of the nip portion of the separation roller pair 107. Specifically, at least a rectangular shape described in detail later is used. It is installed on the lower side at a distance equal to or greater than the thickness of two envelopes 300.

The guide member 107c includes a pair of separation rollers 10
7 and the skew correction roller 108, and more specifically, is bent downward from the vicinity of the nip portion of the separation roller pair 107 to be slightly lower than the nip portion of the skew correction roller 108. Extending to On the other hand, the guide member 108c
Are arranged from the vicinity of the nip portion of the skew feeding correction roller 108 to the vicinity of the nip portion between the transport belt 109a and the roller 109d.

The sheet detection sensor 202 is disposed between the separation roller pair 107 and the skew feeding correction roller 108 and below the guide member 107c. On the other hand, the sheet detection sensor 203 includes a skew correction roller 108 and a drive pulley 109
b and below the guide member 108c.

The guide plate 201 is disposed above the sheet detection sensor 202 and between the separation roller pair 107 and the skew correction roller 108. As shown in FIG.
The leading end of the sheet is positioned close to the main surface of the roller above the skew correction roller 108, so that the sheet that has passed through the separation mechanism 107 is smoothly transferred to the skew correction roller 108.

Each of the sheet detection sensors 202 and 203 is a reflection type sensor that irradiates light and detects passage of a sheet or the like based on a difference in reflectance, and when the reflectance is low, the absence of a sheet is detected. When the reflectance is high, it is detected that the sheet is passing. Further, when the sheet is a long envelope, since the reflectance of the flap portion and that of the main body portion are different, when the reflectance is higher, during passage through the main body portion, when the reflectance is relatively low. Can be detected as being passing through the flap portion.

FIG. 3 is a plan view of the back side showing the configuration of a long envelope as a sheet to be stacked on the sheet stacking section 105. The long envelope 300 shown in FIG. 3 has a general outer shape formed by folding one sheet of paper and bonding a glue margin portion, and has a flap portion 301 as a thin portion.
Further, a marking portion 302 for recognizing the flap portion 301 is formed at an end near the flap portion 301. The marking section 302 has a higher reflectance than the surrounding area.

In the image forming apparatus according to the embodiment, the long envelope 300 is stacked on the sheet stack tray 105a such that the back side faces downward and the flap portion 301 faces the rear end in the feeding direction. Is done. In the image forming apparatus, when the long envelope 300 stacked on the sheet stacking unit 105 is fed, the sheet detection sensors 202 and 203 are arranged at positions facing the marking unit 302 passing therethrough. , 203, the passage of the marking section 302 is detected.

Hereinafter, the long envelope 3 in the sheet transfer section will be described.
The transporting operation of 00 will be described with reference to FIGS. FIG. 2A shows a state immediately before the long envelope 300 is fed, and from this state, the feeding roller 106 and the feeding roller 107 of the separation roller pair 107.
a is rotated in the counterclockwise direction in FIG.
As shown in (b), the uppermost long envelope 300 is sent out, and its leading end passes through the nip portion of the separation roller pair 107 and hits the guide plate 201. At this time, since the leading end of the long envelope 300 passes over the sheet detection sensor 202, the leading end of the long envelope 300 is detected by the sheet detection sensor 202.

When a plurality of long envelopes 300 are sent out by the feed roller 106, as described above, they are separated by the separation roller pair 107, and
Only the sheet is conveyed by the separation roller pair 107, and its leading end abuts on the guide plate 201.

The long envelope 300 whose leading end in the transport direction abuts on the guide plate 201 is thereafter moved to the guide plate 20.
1 is supplied to the nip portion of the skew feeding correction roller 108 while sliding smoothly, and is conveyed by the separation roller pair 107 and the skew feeding correction roller 108.

At this time, the long envelope 300 is as shown in FIG.
As shown in the figure, the separation roller pair 107 and the skew feed correction roller 1
The sheet is conveyed while flexing and deforming at a position between the positions 08 and 08. Also, at this time, since the leading end of the long envelope 300 passes over the sheet detection sensor 203, the leading end of the long envelope 300 is detected by the sheet detection sensor 203. Then, when the sheet detection sensor 203 detects the passage of the leading end of the long envelope 300, the upper delivery roller 107a of the separation roller 107 is retracted upward, and only the skew feeding correction roller 108 is conveyed. The front end of the envelope 300 is fed into the nip between the conveying belt 109a and the roller 109d of the sheet conveying unit 109 while correcting the skew. At this time, the linear speed of sheet conveyance by the sheet conveying unit 109 is set to be equal to or slightly higher than the linear speed of the skew feeding correction roller 108. Thereafter, as shown in FIG. 2D, the flap portion 301 at the rear end of the long envelope 300 passes through the nip portion of the separation roller pair 107.

In the image forming apparatus according to the embodiment, when the flap portion 301 passes through the nip portion of the separation roller pair 107, as shown in FIG. Based on this detection signal, the feed roller 106 and the separation roller pair 107 are driven to rotate so as to start feeding the next long envelope 300b, as shown in FIG. The previously fed long envelope 300a is nipped and conveyed by the conveying belt 109a and the roller 109d with the skew feeding correction roller 108, and the long envelope 300
b passes through the separation roller pair 107 and the next long envelope 30
The leading end of Ob overlaps the flap 301 which is the rear end of the long envelope 300a.

That is, the relationship between the linear velocity of sheet conveyance by the feed roller 106 and the linear velocity of sheet conveyance by the separation roller 107 is such that the flap portion 301 of the long envelope 204a When the nip position is reached, the leading end of the next long envelope 204b is set to come to the nip position.

Then, as shown in FIG. 2 (f), while the overlapping state of the leading end portion of the later long envelope 300b and the flap portion 301 of the preceding long envelope 300a is maintained, they are simultaneously conveyed. 2 (g), the ink is supplied to the inkjet discharge unit 102. Further, the marking portion 302 of the long envelope 300a is used as the sheet detection sensor 2
03, and based on the detection result, each of the print heads 102a to 102
The ink ejection timing by d is controlled, and a full-color image is formed on the long envelope 300.

According to the above-described operation, according to the image forming apparatus of the embodiment, the flap portion 301 of the long envelope fed first and the leading end portion of the long envelope fed later overlap. Since the print heads 102a to 102c are conveyed to the inkjet discharge unit 102, the print heads 102a to 102c
This makes it possible to prevent troubles such as contact with the 102d, stabilize the image formation of the long envelope, and form an image on the entire surface other than the flap portion.

[Second Embodiment] A second embodiment of the present invention will be described with reference to FIGS. 4 (a) and 4 (b). FIGS. 4A and 4B are schematic cross-sectional views of a sheet transfer unit in the image forming apparatus according to the second embodiment, and the same parts as those in the first embodiment are denoted by the same reference numerals. The description is omitted as appropriate.

The image forming apparatus according to the second embodiment is similar to the above-described first embodiment, and includes an image forming apparatus main body in which the image forming means is disposed and a sheet feeding apparatus for feeding a sheet to the image forming means. The image forming apparatus is configured to be connected to a feeding unit, and the configuration of the image forming apparatus main body is the same as that of the first embodiment.

In the second embodiment, as shown in FIG. 4, the sheet feeding section employs a so-called lower sheet feeding method, and the lowermost sheet among the stacked sheets (long envelope 300) is used. The sheet is fed by a feed roller 404. Here, the feeding roller 404 is a half-moon roller, and is rotated in the clockwise direction in FIG. 4 so that only the lowermost long envelope of the loaded long envelope 300 is moved by a predetermined amount. It is designed to be fed.

In the second embodiment, a conveying roller 403 for conveying a sheet is disposed in a sheet conveying path between the feeding roller 404 and the above-described sheet conveying section 109. The sheet detection sensor 405 that detects the passage of the sheet is disposed at the position where the sheet passes.

The transport roller 403 is driven to rotate in a counterclockwise direction in FIG. 4 so that the long envelope 300 fed by the feed roller 404 is moved to each print head 102a.
The sheet is conveyed to the sheet conveying section 109 in which the sheet conveyance units 109 to 102d are arranged. In addition, the long envelope 3 by the half-moon-shaped feeding roller 404 is used.
The feed amount of 00 is set to a distance that allows the leading end of the loaded long envelope 300 to be transported from the wall 105 c to the transport roller 403.

The sheet detection sensor 405 is a reflection type sensor similar to the sheet detection sensors 202 and 203 in the first embodiment, and can detect the front end portion, the rear end portion, and the marking portion 302 of the long envelope 300. It has become.

The direction in which the long envelope 300 is loaded,
And the long envelope 30 loaded with the sheet detection sensor 405
The arrangement for 0 is the same as in the first embodiment.

Hereinafter, the feeding operation of the thus configured long envelope 300 according to the second embodiment will be described.

In the second embodiment, the feeding roller 404 is driven to rotate clockwise in FIG. 4, and the long envelope 300a reaches the transport roller 403 and is driven to rotate counterclockwise. The long envelope 300 a is transported to the sheet transport unit 109 by the transport roller 403. At this time, the marking portion 302 formed on the long envelope 300a is detected by the sheet detection sensor 405, and this detection signal is output.

Then, the feed roller 404 is driven to rotate clockwise in FIG. 4 based on this detection signal, and as shown in FIG.
Start feeding. At this time, the feed linear speed of the feed roller 404 is substantially the same as the transport linear speed of the transport roller 403.

By repeating the above operation, the second
Also in the second embodiment, the stacked long envelopes 300 can be reliably transported without interruption, and the same effects as those of the first embodiment can be obtained.

[Third Embodiment] A third embodiment of the present invention will be described with reference to FIGS. FIGS. 5A to 5C are schematic cross-sectional views of a sheet transfer unit in the image forming apparatus according to the third embodiment, and the same parts as those in the first embodiment are denoted by the same reference numerals. The description is omitted as appropriate.

The image forming apparatus according to the third embodiment is similar to the above-described first embodiment, and includes an image forming apparatus main body in which the image forming means is disposed and a sheet feeding apparatus for feeding sheets to the image forming means. The transmission unit is connected. Here, the sheet feeding unit of the third embodiment is the same as the first embodiment.
Similarly to the sheet feeding unit of the embodiment, a so-called upper sheet feeding method is adopted, and the sheet is stacked on a sheet stacking tray (see FIG. 1) configured to be vertically movable with respect to a wall 105c in the sheet feeding unit. A feed roller 106 for feeding the fed sheet to the image forming apparatus main body is arranged. In this embodiment, a claw separation method is adopted as a sheet separation method, and a structure in which a separation roller pair or the like is not used is adopted.

The configurations of the image forming means and the sheet conveying section 109 on the image forming apparatus main body side are the same as those in the first embodiment, and the illustration of the conveying belt 109a and the like is omitted in FIG.

In the sheet transfer section of the third embodiment, the cam-shaped pressing member 503 and the position of the pressing member 503 are detected in the sheet conveying path between the feeding roller 106 and the roller 109d. Member detection sensor 505 is disposed. In the sheet transfer section of the third embodiment, the distance between the feeding roller 106 and the roller 109d is shorter than the length of the long envelope 300 in the conveying direction, and the length of the sheet fed by the feeding roller 106 is shorter. The envelope 300 can be transferred to the roller 109d.

The pressing member 503 is disposed close to the feeding roller 106, and extends from an upward position shown in FIGS. 5A and 5C to a horizontal position shown in FIG. Is configured to be rotatable along the sheet conveying path.

The pressing member 503 is urged in the counterclockwise direction in FIG. 5 by a spring (not shown), and as shown in FIGS. 5 (a) and 5 (c), the distal end portion 503a in the initial state. Face upward (vertically). In this initial state, the pressing member 50
3 is higher than the position of the uppermost sheet (the long envelope 300) fed by the feed roller 106.
It is located on the upper side.

The member detection sensor 505 includes a pressing member 503
5B, when the pressing member 503 reaches a predetermined angle as shown in FIG. 5B, this is detected and turned on.

The loading direction of the long envelopes 300 is the same as that of the first embodiment. In this embodiment, it is not necessary to form the marking portion 302 on the long envelope 300.

Hereinafter, the feeding operation of the thus configured long envelope 300 according to the third embodiment will be described.

In the third embodiment, when the feeding roller 106 is driven to rotate in the counterclockwise direction in FIG. 5 and the long envelope 300 is fed, the leading end of the long envelope 300 is moved. When the pressing member 503 abuts against the pressing member 503,
Rotates clockwise in FIG. 5 against the urging force of the spring (see FIG. 5B). At this time, the member detection sensor 5
05 outputs an ON detection signal.

Here, since the pressing member 503 is installed close to the feeding roller 106 as described above, while the long envelope 300 is being fed by the feeding roller 106, the pressing of the envelope is As a result, it is rotated clockwise in FIG. Then, the long envelope 300
When the flap portion 301, which is the rear end portion, passes through the feeding roller 106, the pressing member 503 returns to the initial position at the front end portion 503a. At this time, the detection signal of the member detection sensor 505 is turned off, and FIG. As shown in FIG. 5 (a), the distal end portion 503a of the pressing member 503 is used to
Is lifted upward.

When the detection signal of the member detection sensor 505 is turned off, the feed roller 106 is driven to rotate in the counterclockwise direction in FIG.
The feeding of b is started (FIG. 5A). Feed roller 10
6, the long envelope 300b is similarly conveyed while pressing the pressing member 503 and rotating clockwise in the drawing. At this time, the linear velocity of the feeding roller 106 is faster than the linear velocity of the sheet conveying unit 109. For this reason, the feeding speed of the later long envelope 300b becomes faster than the feeding speed of the long envelope 300a that has been transported earlier, and as shown in FIG.
Immediately after 0 passes through the leading end portion 503a of the pressing member 503, the pressing member 503 is rotated by the subsequent long envelope 300b, and the flap portion 301 of the long envelope 300a that has been conveyed is moved downward by the pressing member 503. Pushed in the direction.

As shown in FIG. 5C, since the linear velocity of the feeding roller 106 is faster than the linear velocity of the sheet conveying section 109, the subsequent long envelope 300b is not in contact with the roller 109d. At the time when the long envelope 300b is nipped and conveyed by the illustrated conveyance belt, the long envelope 300b is conveyed while being overlapped on the flap portion 301 of the previous long envelope 300a, and an image can be formed by the ink jet discharge unit 102.

By repeating the above operation, the third
Also in the second embodiment, the stacked long envelopes 300 can be reliably transported without interruption, and the same effects as those of the first embodiment can be obtained. Further, in the third embodiment, after the flap portion 301 of the preceding long envelope 300 is bent downward by the pressing member 503 as the urging member, the leading end of the next long envelope 300 overlaps. Thus, the flap 301 is prevented from warping or floating, and the reliability of the image forming process is improved.

In each of the above embodiments, an example in which the present invention is applied to a printer has been described. However, the present invention is not limited to this, and can be applied to other image forming apparatuses such as a copying machine. is there.

Further, in each of the above-described embodiments, an example in which an ink jet system is adopted as an image forming unit has been described. However, the present invention is not limited to this. May be adopted.

[0075]

As described above, the present invention provides:
In the present invention, the front end of a long envelope coming from behind during conveyance is superimposed on the sheet, especially the rear end flap portion of the long envelope, and conveyed to form an image. Can be prevented, and the above-mentioned problems such as image defects and conveyance defects can be eliminated, thereby improving the reliability of the image forming apparatus and the reliability of the apparatus. is there.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a first embodiment.

FIG. 2 is a schematic cross-sectional view of a first embodiment of a sheet transfer unit and a diagram illustrating a state of feeding and transporting a long envelope;
(A) shows an initial state before feeding of the long envelope, (b) shows a state immediately after starting feeding of the long envelope, and (c) shows a state where the long envelope reaches the skew correction roller. (D) shows a state in which the long envelope has reached the sheet conveying section, (e) shows a state in which feeding of the next long envelope has started, and (f) shows a state in which each long envelope has Indicates a state where the ends are conveyed while overlapping,
(G) shows a state in which each of the long envelopes has reached below the ink jet discharge section.

FIG. 3 is a plan view on the back side showing a configuration of a long envelope as a sheet to be stacked on a sheet stacking unit.

FIG. 4 is a schematic cross-sectional view of a second embodiment of a sheet delivery unit and a diagram illustrating a state of feeding and transporting a long envelope;
(A) shows a state at the time of feeding by the feed roller, and (b) shows a state where the feed roller is on standby.

FIG. 5 is a schematic cross-sectional view of a third embodiment of a sheet transfer unit and a diagram illustrating a state of feeding and transporting a long envelope;
(A) shows a state in which the flap portion of the long envelope is pushed up by the pressing member, and (b) shows a state in which the pressing member is pressed by the distal end portion of the subsequent long envelope, and the flap portion of the preceding long envelope is lowered. (C) shows a state in which each of the long envelopes is conveyed in an overlapping manner.

[Explanation of symbols]

 101 Image Forming Apparatus Main Body 102 Inkjet Discharge Units 102a-d Print Head 103 Sheet Feeding Unit 104 Sheet 105 Sheet Stacking Unit 106 Feeding Roller 107 Separation Roller 108 Skew Correction Roller 109 Sheet Transporting Unit 109a Transport Belt 109b Drive Pulley 109c Followed Pulley 109d Rollers 110a-e Spurs 201 Guide plates 202, 203 Reflective sensors 204 Sheets 300 Long envelopes 301 Flap portions 302 Marks 403 Convey rollers 404 Feed rollers 405 Sheet detection sensors 503 Pressing members (biasing members) 505 Transmission sensors

Continued on the front page F-term (reference) 2C059 AA04 AA12 AA26 AA59 3F101 LA01 LA07 LB05 3F102 AA01 AA11 AB02 BA02 BA07 CA05 CB01 DA08 EA03 FA08 3F343 FA17 FB01 FC11 GA01 GB02 GC01 GD01 JA01 KA02 MA03 MA16 MA13 MB03

Claims (11)

[Claims] 1. A sheet stacking unit for stacking sheets, a sheet feeding unit for sequentially feeding sheets stacked on the sheet stacking unit, an image forming unit for forming an image on a sheet, and the sheet feeding unit. And a sheet conveying unit that conveys the sheet fed by at least to the image forming unit, wherein the sheet conveying unit is configured such that a part of a sheet fed later is part of a sheet fed earlier. An image forming apparatus, wherein the sheet is conveyed to the image forming unit so as to overlap. 2. The image forming apparatus according to claim 1, wherein the sheet stacking unit can stack a long envelope as a sheet. 3. The sheet stacking means is stacked so that a flap portion of the long envelope is located at a rear end in a feeding direction, and the sheet conveying means is a sheet having a flap portion of a long envelope fed earlier. 3. The image forming apparatus according to claim 2, wherein the long-form envelope fed later is conveyed to the image forming unit such that a part of the long envelope overlaps. 4. A sheet feeding means for detecting a flap portion of the long envelope, wherein the sheet feeding means detects a flap portion of the long envelope when the detection means detects the flap portion of the long envelope. The image forming apparatus according to claim 3, wherein feeding is started. 5. The image forming apparatus according to claim 1, wherein the image forming unit includes one or more print heads that eject ink onto a sheet by an ink jet method.
The image forming apparatus as described in the above. 6. The image forming apparatus according to claim 1, wherein the sheet feeding unit separates and feeds the sheets stacked on the sheet stacking unit into one sheet. 7. An image forming apparatus according to claim 1, wherein said sheet feeding means includes a skew feeding correcting means for correcting skew of the sheet. 8. The sheet feeding device according to claim 1, wherein the sheet feeding unit sequentially feeds the sheets stacked on the sheet stacking unit from a top one.
The image forming apparatus as described in the above. 9. The sheet feeding means according to claim 1, wherein the sheet feeding means sequentially feeds the sheets stacked on the sheet stacking means from the lowest one.
The image forming apparatus as described in the above. 10. An urging member for urging a rear end side of a sheet conveyed by said sheet conveying means downward at a transfer portion between said sheet feeding means and said sheet conveying means. Any one of claims 1 to 8
The image forming apparatus as described in the above. 11. The sheet feeding device according to claim 11, wherein the urging member urges a rear end side of the sheet downward by moving while being abutted against a leading end of the sheet fed by the sheet feeding unit. The image forming apparatus according to claim 10, wherein