JP3668711B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there has been known an image forming apparatus capable of forming an image on a wide sheet having a size equal to or larger than, for example, a Japanese Industrial Standard (JIS) A row No. 1 (hereinafter referred to as “A1”). This type of image forming apparatus includes an image forming unit including, for example, a photosensitive drum, a main charger, an LED print head, and a developing device. The surface of the photosensitive drum is uniformly charged by the main charger and then selectively exposed by the LED print head, whereby a so-called electrostatic latent image is written. The electrostatic latent image is developed into a toner image by a developing device, and the toner image is transferred onto a sheet.
[0003]
In the image forming apparatus, for example, a paper storage unit for storing paper such as roll paper is provided at a lower portion thereof, and the paper is sent out from the paper storage unit toward the image forming unit at a predetermined timing. It has become.
Some image forming apparatuses of this type include a manual paper feeding unit for manually setting paper in addition to the paper storage unit. In the manual sheet feeding unit, for example, a registration roller for sending out a sheet at a predetermined timing toward the image forming unit is arranged. The registration rollers are arranged so as to extend in the width direction substantially orthogonal to the sheet conveyance direction, and are provided with a driven roller facing upward.
[0004]
A driving mechanism is connected to the rotation shaft of the registration roller, and the registration roller is rotated when a motor included in the driving mechanism is rotationally driven. The registration roller has, for example, eight registration roll bodies arranged in parallel along the width direction.
The driven roller has, for example, eight driven roll bodies corresponding to each registration roll body. Each driven roll body is brought into pressure contact with a corresponding registration roll body at a predetermined nip pressure, and is rotated as the registration roller rotates. The paper supplied to the manual paper feed unit is sandwiched between the registration roller and the driven roller, and is sent between them to the image forming unit.
[0005]
[Problems to be solved by the invention]
However, due to variations in assembly accuracy, the nip pressure between each registration roll body and the corresponding driven roll body may vary. In this case, when a wide sheet is manually fed, the sheet may be sent obliquely (skew) with respect to the sheet conveyance direction.
In view of this, a configuration has been proposed in which a feed roller for supplying a sheet to the registration roller side is disposed closer to the sheet conveyance direction than the registration roller. The feed rollers are arranged so as to extend substantially parallel to the registration rollers, and have, for example, eight (the same number as the registration roll bodies) feed roll bodies arranged in parallel along the width direction. Of the eight registration roll bodies, the two registration roll bodies arranged at both ends of the registration roller are, for example, on the outer side in the width direction than the two feed roll bodies arranged at both ends of the feed roller. Is arranged. That is, the sheet passing range in the width direction of the feed roller is on the inner side than the sheet passing range of the registration roller.
[0006]
According to this configuration, the sheet can be supplied straight to the registration roller along the sheet conveyance direction by the action of the feed roller. Therefore, even when a wide sheet is manually fed, the sheet can be fed straight along the sheet conveyance direction from the registration roller to the image forming unit without being skewed.
However, in the above configuration, since the sheet passing range in the width direction of the feed roller is on the inner side of the sheet passing range of the registration roller, when a wide sheet is manually fed, when passing the feed roller There has been a problem that wrinkles in the width direction of the generated paper cannot be released outside the sheet passing range of the registration rollers, and wrinkles may occur.
[0007]
In particular, when manually feeding thin paper such as tracing paper or so-called material paper, wrinkles are likely to occur.
The present invention has been made under such a background, and an object of the present invention is to provide an image forming apparatus in which paper is not easily wrinkled during paper feeding.
[0008]
[Means for Solving the Problems and Effects of the Invention]
In order to achieve the above object, an invention according to claim 1 is an image forming apparatus (1) having an image forming section (14) capable of forming an image on a wide sheet of A1 size or larger, wherein the image forming section includes And a registration roller (43) arranged to extend in a width direction substantially orthogonal to the sheet conveyance direction (A), and a sheet more than the registration roller. A feed roller (47) disposed on the front side in the conveying direction so as to extend substantially parallel to the registration roller, and for feeding paper to the registration roller side; The image forming apparatus is characterized in that the range (R2) is inside the sheet passing range (R1) of the feed roller.
[0009]
In addition, the alphanumeric characters in parentheses represent corresponding components in the embodiments described later. The same applies hereinafter.
According to this configuration, even when a wide sheet is fed, the bending in the width direction of the sheet that occurs when the sheet passes through the feed roller is reduced in the sheet passing range (R2) of the registration roller when the sheet passes through the registration roller. Can escape to the outside. Accordingly, it is difficult for the paper to be wrinkled during paper feeding.
[0010]
According to a second aspect of the present invention, the registration roller (43) has a plurality of registration roll bodies (43b) for transporting paper, and the feed roller (47) is for transporting paper. If it has a plurality of feed roll bodies (47b) and the resist roll body is configured to be smaller than the feed roll body, it is possible to prevent wrinkles from occurring more suitably.
Further, as in the invention described in claim 3, the feed roll body (47b) is preferably formed of a sponge.
[0011]
For example, when the paper is supplied from the feed roller to the registration roller side, the registration roller is stopped. Thus, the leading edge of the sheet fed by the feed roller is temporarily stopped (registered) by the registration roller, and the sheet conveyance direction is adjusted. Since the feed roller continues to rotate, the leading edge of the sheet is bent in the sheet conveyance direction between the feed roller and the registration roller.
According to the configuration of the present invention, by forming the feed roll body with a sponge having low frictional resistance, the paper can be slid at the feed roller at the time of registration, and the bending occurring obliquely with respect to the paper conveyance direction can be released. Wrinkles are less likely to occur.
[0012]
According to a fourth aspect of the present invention, the registration roller (43) and the feed roller (47) are provided in a manual paper feed section (40) for manually setting paper. The image forming apparatus according to any one of?
According to this configuration, it is possible to provide an image forming apparatus in which when a wide sheet is manually fed from the manual sheet feeding unit, the sheet is less likely to be wrinkled.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
FIG. 1 is a schematic sectional view showing a configuration of a copying machine 1 according to an embodiment of the present invention. The copying machine 1 is an image forming apparatus capable of forming an image on a wide sheet up to, for example, A0 size. In FIG. 1, the right side is assumed to be the front and the left side is assumed to be the rear.
[0014]
The copying machine 1 is partitioned by a substantially rectangular housing 2, and includes a document reading unit 10 having a reading device 13 for reading a document, a paper storage unit 11 for storing paper such as roll paper, and conveyance. An image forming unit 14 for transferring a toner image based on an image of a document read from the reading device 13 to a sheet to be read, a fixing device 15 for fixing the toner image transferred to the sheet, and the like are provided. .
The document reading unit 10 includes, for example, two pairs of document conveying rollers 25 and 26 extending in the left-right direction. On the upper surface of the housing 2, a placing table 4 for setting a document is provided. The document is set on the placing table 4 so that the front surface faces downward. When an operator operates, for example, a start button of an operation panel (not shown) protruding from the upper surface of the housing 2 with the document set on the mounting table 4, the document passes through the document transport rollers 25 and 26. It is designed to be conveyed from the near side to the rear side.
[0015]
The reading device 13 is disposed between the two pairs of document conveying rollers 25 and 26. The document passes over a transparent contact glass (not shown) in the process of being conveyed backward through the document conveying rollers 25 and 26. The reading device 13 is disposed below the contact glass, and can read an image of a document passing over the contact glass from below.
A pressing roller 31 extending in the left-right direction, for example, is disposed above the reading device 13. The pressing roller 31 presses the document passing over the contact glass so that it does not float from the surface of the contact glass, and reflects when the light emitted from the reading device 13 toward the document is reflected by the document when reading the document. A so-called shading correction function for correcting variations in the amount of light is also provided.
[0016]
The image forming unit 14 is disposed in the upper part of the housing 2 and includes a photosensitive drum 16 that is driven to rotate counterclockwise in FIG. The photosensitive drum 16 has a photosensitive layer on the outer peripheral surface thereof, and is uniformly charged by the discharge of the main charger 17, and then the LED print head 18 based on the image of the original read from the reading device 13. It is exposed by the light irradiated from. As a result, a so-called electrostatic latent image is formed on the surface of the photosensitive drum 16.
[0017]
Toner is attached to the surface of the photosensitive drum 16 on which the electrostatic latent image is formed by the developing device 19 to form a toner image. When the photosensitive drum 16 is further rotated, the toner image is transferred to the conveyed paper by the transfer device 20. The toner remaining on the surface of the photosensitive drum 16 after the toner image is transferred is collected by the cleaning device 21.
The sheet on which the toner image has been transferred is guided to the fixing device 15, subjected to fixing processing by the fixing device 15, and then discharged to the outside of the housing 2 by the discharge roller 22.
[0018]
On the rear side of the housing 2, a sheet conveyance path 12 for guiding the sheet from the sheet storage unit 11 to the image forming unit 14 extends straight up and down. In the middle of the paper transport path 12, a registration roller 23 for sending the paper stored in the paper storage unit 11 toward the image forming unit 14 at a predetermined timing is disposed. Further, a feed roller 24 for supplying paper to the registration roller 23 side is disposed on the front side of the registration roller 23 in the paper conveyance direction.
[0019]
At the time of image formation, the paper stored in the paper storage unit 11 is sent to the registration roller 23 side by the feed roller 24, and the conveyance is temporarily stopped when the leading end of the paper reaches the registration roller 23. Then, the rotation of the registration roller 23 is started so that the sheet reaches the image forming unit 14 at the timing when the toner image formed on the surface of the photosensitive drum 16 in the above-described manner comes to a position facing the transfer device 20. It has come to be.
[0020]
A cutter mechanism 27 for cutting the roll paper is disposed between the registration roller 23 and the feed roller 24. In the vicinity of the cutter mechanism 27, a paper detection sensor (not shown) for detecting the passage of paper is provided. Based on the detection signal of the paper detection sensor, the length of the fed roll paper is determined. The roll paper is cut by the cutter mechanism 27 with a length corresponding to the detected paper size.
[0021]
The copier 1 according to the present embodiment is provided with a manual paper feed unit 40 for manually setting cut sheets in addition to the paper storage unit 11. A paper supply port 41 for manually supplying paper is formed on the front surface of the housing 2, and the paper is supplied to the manual paper feed unit 40 by inserting the leading end of the paper from the paper supply port 41. Can be done.
FIG. 2 is an enlarged cross-sectional view of a main part showing the configuration of the manual paper feed unit 40. With reference to FIG. 2, a manual feed unit 40 is provided with a registration roller 43 for sending out a sheet at a predetermined timing toward the image forming unit 14, for example. The registration rollers 43 are arranged so as to extend in a width direction substantially orthogonal to the paper transport direction A, and are provided with a driven roller 44 facing the upper side.
[0022]
The registration roller 43 is rotatably held by a rotation shaft 43a. A driving mechanism (not shown) is connected to the rotating shaft 43a, and the motor included in the driving mechanism is driven to rotate, whereby the registration roller 43 is rotated counterclockwise in FIG. Yes.
The driven roller 44 is rotatably held by a rotating shaft 44a. The driven roller 44 is in pressure contact with the registration roller 43, and is rotated clockwise in FIG. 2 as the registration roller 43 rotates.
[0023]
The sheet supplied to the registration roller 43 is sandwiched between the registration roller 43 and the driven roller 44, and is sent to the image forming unit 14 through them.
The paper transport path 46 of the manual paper feed unit 40 is formed by an upper guide plate 45a and a lower guide plate 45b. The rotation shaft 43a of the registration roller 43 is held by a machine body side plate (not shown) below the lower guide plate 45b, and the rotation shaft 44a of the driven roller 44 is held by the upper guide plate 45a.
[0024]
A feed roller 47 for supplying paper to the registration roller 43 side is disposed on the front side of the registration roller 43 in the paper conveyance direction A. The feed roller 47 is rotatably held by a rotation shaft 47 a arranged so as to extend substantially parallel to the rotation shaft 43 a of the registration roller 43. The rotation shaft 47a is connected to the drive mechanism for rotating the registration roller 43 described above, and the feed roller 47 is rotated counterclockwise in FIG. 2 when the motor included in the drive mechanism is driven to rotate. It has become so. The rotation shaft 47a of the feed roller 47 is held by a machine body side plate (not shown) below the lower guide plate 45b.
[0025]
The feed roller 47 is attached in a state pressed against the upper guide plate 45a from below, and the paper supplied from the paper supply port 41 to the manual paper feeding unit 40 is fed to the upper guide plate 45a by the feed roller 47. It is sent to the registration roller 43 side along the lower surface.
In the present embodiment, the upper part from the upper guide plate 45a of the housing 2 serves as a drawer part 2a that can be pulled out to the front side (see FIG. 1). An opening is formed on the upper surface of the housing 2 by pulling out the drawer portion 2a toward the front side, and maintenance inside the housing 2 can be performed by inserting a hand through the opening. ing.
[0026]
When the drawer portion 2a is pulled out to the near side, the upper guide plate 45a is displaced to the near side with respect to the lower guide plate 45b, and the registration roller 43 and the feed roller 47 attached to the lower guide plate 45b side are exposed. ing. Accordingly, by pulling out the drawer portion 2a, a hand can be put in from the opening formed on the upper surface of the housing 2, and not only the driven roller 44 but also the registration roller 43 and the feed roller 47 can be maintained.
[0027]
Further, when a paper jam (JAM) occurs in the paper conveyance path 46 of the manual paper feed unit 40, the jammed paper can be easily removed by pulling out the drawer 2a and turning a paper jam release dial (not shown). it can.
Further, in the present embodiment, the sheet can be supplied straight to the registration roller 43 along the sheet conveyance direction A by the action of the feed roller 47. Therefore, even when a wide sheet is manually fed, the sheet can be fed straight along the sheet conveyance direction A from the registration roller 43 toward the image forming unit 14 without being skewed.
[0028]
FIG. 3 is a plan view of the lower guide plate 45b as viewed from above, and shows only the main part. 2 and 3, the registration roller 43 includes, for example, six registration roll bodies 43b arranged in parallel along the width direction. Each registration roll body 43b is made of, for example, rubber, and its outer peripheral surface protrudes upward from the lower guide plate 45b and faces the paper conveyance path 46. Of the six registration roll bodies 43b, the central two roll bodies are arranged with a slightly shorter interval than the short side of the A4 size paper, and the registration rollers 43 have a minimum of A4 size paper. It can be conveyed in the vertical direction.
[0029]
The driven roller 44 has, for example, six driven roll bodies 44b that face each registration roll body 43b. Each driven roll body 44b is made of, for example, POM (polyoxymethylene), and its outer peripheral surface protrudes downward from the upper guide plate 45a and faces the paper conveyance path 46.
Each driven roll body 44b is brought into pressure contact with the corresponding registration roll body 43b with a predetermined nip pressure, and is rotated as the registration roller 43 rotates.
[0030]
The feed roller 47 has, for example, eight feed roll bodies 47b (more than the resist roll bodies 43b) arranged in parallel along the width direction. Each feed roll body 47b is formed of, for example, sponge, and its outer peripheral surface projects upward from the lower guide plate 45b and faces the paper conveyance path 46. The outer surface of the feed roll body 47b is pressed against the lower surface of the upper guide plate 45a and attached in a distorted state. Thereby, the feed roll body 47b rotates in a state where the outer peripheral surface thereof is rubbed against the lower surface of the upper guide plate 45a.
[0031]
The registration roll body 43b of the registration roller 43 and the feed roll body 47b of the feed roller 47 are arranged in a staggered manner. Accordingly, it is possible to prevent the rigidity of the lower guide plate 45b from being lowered as compared with the case where the registration roll bodies 43b and the feed roll bodies 47b are arranged side by side along the paper transport direction A.
The feature of this embodiment is that two of the eight feed roll bodies 47b are arranged at two end portions of the feed roller 47, and the two feed roll bodies 47b are arranged at both end portions of the registration roller 43. It exists in the point arrange | positioned so that it may become the width direction outer side from the roll body 43b. That is, the sheet passing range R2 in the width direction of the registration roller 43 is inside the sheet passing range R1 of the feed roller 47.
[0032]
According to this configuration, even when a wide sheet is manually fed from the manual sheet feeding unit 40, the bending in the width direction of the sheet that has occurred when the sheet passes through the feed roller 47 is registered when the sheet passes through the registration roller 43. The roller 43 can escape to the outside of the sheet passing range R2. Accordingly, it is difficult for the paper to be wrinkled during paper feeding.
When image formation is performed in the copying machine 1, for example, in response to an operator operating the operation panel to select manual feed and inserting paper from the paper supply port, the feed roller 47 of the manual paper feed unit 40 is used. Starts to rotate.
[0033]
For example, two sheet detection sensors 48 and 49 for detecting the passage of the sheet in the sheet conveyance path 46 are arranged side by side along the sheet conveyance direction A at the approximate center of the upper surface of the upper guide plate 45a in the width direction. It has been. Each of the paper detection sensors 48 and 49 is a so-called optical reflection type, and detects whether or not the irradiated light is reflected on the paper and is incident on the sensors 48 and 49 again. It is to detect.
[0034]
The sheet detection sensor 48 disposed on the front side in the sheet transport direction A is disposed immediately upstream of the position where the feed roll body 47b contacts the upper guide plate 45a, and detects the leading edge of the manually fed sheet. Thus, immediately after that, the feed roller 47 can be rotated to feed paper.
The drive mechanism for rotating the feed roller 47 and the registration roller 43 is provided with a clutch (not shown) for switching the rotation and stop of the registration roller 43. When manual sheet feeding is selected and the leading end of the sheet is inserted from the sheet supply port 41, the sheet is fed to the registration roller 43 side by the rotating feed roller 47. At this time, the registration roller 47 is stopped by the action of the clutch of the drive mechanism. As a result, the sheet fed by the feed roller 47 is stopped (registered) at the position (nip position) where the leading edge of the sheet is in contact with the registration roller 43 and the driven roller 44, and the sheet conveyance direction is adjusted. Since the feed roller 47 continues to rotate, the leading edge of the sheet is bent in the sheet conveyance direction A between the feed roller 47 and the registration roller 43. In this embodiment, by forming the feed roll body 47b with a sponge having low frictional resistance, the paper can be slid by the feed roller 47 during registration, and the bending that occurs obliquely with respect to the paper conveyance direction can be released. It is less likely to occur.
[0035]
The paper detection sensor 48 detects the leading edge of the paper that has passed the registration roller 43 and transmits a detection signal to a control unit (not shown) provided in the copying machine 1. The control unit switches the clutch of the drive mechanism to start the rotation of the registration roller 43 after a predetermined time (for example, 0.75 seconds) has elapsed since the detection signal from the paper detection sensor 48 has been received. As a result, the sheet fed by the registration roller 43 reaches the image forming unit 14 at the timing when the toner image on the surface of the photosensitive drum 16 comes to a position facing the transfer device 20.
[0036]
On the other hand, the paper detection sensor 49 disposed on the rear side in the paper transport direction A is for detecting JAM. That is, if the detection signal from the paper detection sensor 49 is not yet transmitted even after a predetermined time has elapsed since the registration roller 43 started to rotate, the control unit determines that JAM has occurred and copies the copy. The image forming operation of the machine 1 is stopped, and the operator is notified of the occurrence of JAM by, for example, a warning sound.
[0037]
The present invention is not limited to the contents of the above embodiments, and various modifications can be made within the scope of the claims.
For example, the configuration of the registration rollers and the feed rollers of the manual sheet feeding unit 40 is configured to have a plurality of roll bodies 43b and 47b as long as the sheet passing range of the registration rollers is inside the sheet passing range of the feed rollers. Not limited to this, each roll may be constituted by a single roll body that is long in the axial direction.
[0038]
The configuration of the registration roller and the feed roller as described above is not limited to the manual sheet feeding unit 40, for example, a registration disposed in the sheet conveyance path 12 for guiding the sheet from the sheet storage unit 11 toward the image forming unit 14. You may apply to the roller 23 and the feed roller 24. FIG.
Further, although the copying machine 1 has been described as an embodiment of the present invention, the present invention is not limited to the copying machine but can be applied to an image forming apparatus such as a printer and a facsimile.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a configuration of a copying machine according to an embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of a main part showing a configuration of a manual paper feed unit.
FIG. 3 is a plan view of the lower guide plate as viewed from above.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Copier 14 Image formation part 40 Manual paper feed part 43 Registration roller 43b Registration roll body 47 Feed roller 47b Feed roll body A Paper conveyance direction R1, R2 Paper passing range

Claims (4)

An image forming apparatus having an image forming unit capable of forming an image on a wide sheet of A1 size or larger,
A roller for sending out a sheet at a predetermined timing toward the image forming unit, and a registration roller disposed so as to extend in a width direction substantially orthogonal to the sheet conveyance direction;
A feed roller for supplying paper to the registration roller side, which is disposed on the front side in the paper conveyance direction from the registration roller so as to extend substantially parallel to the registration roller.
An image forming apparatus, wherein a sheet passing range in the width direction of the registration roller is inside a sheet passing range of the feed roller. The registration roller has a plurality of registration roll bodies for conveying paper,
The feed roller has a plurality of feed roll bodies for conveying paper,
The image forming apparatus according to claim 1, wherein the resist roll body is configured to be smaller than the feed roll body. The image forming apparatus according to claim 2, wherein the feed roll body is formed of a sponge. The image forming apparatus according to claim 1, wherein the registration roller and the feed roller are provided in a manual paper feed unit for manually setting paper.

Images