JP3092986B2 - Paper transport positioning device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet transport positioning device for transporting a sheet while positioning the sheet on a recording section in an image forming apparatus such as a copying machine or a printer.

[0002]

2. Description of the Related Art In a paper transport positioning device used in this type of equipment, a paper is positioned by abutting a paper against a reference guide surface. In this case, it is generally known that the bottom surface of the narrow groove is used as a guide surface so as not to buckle the paper, and the following three methods are employed as a method of forming a guide having this groove. . 1. A groove is made by cutting a metal block that serves as a guide. 2. A member forming the bottom of the groove and a member forming the side surface are formed separately, and these are combined to form a guide. 3. Created by integral molding of a synthetic resin mold.

[0003]

According to the first method,
Burrs are formed at the bottom of the groove to cause a paper jam, and the processing cost becomes expensive. Further, in the second method, a gap may be formed at a place where members are combined with each other, and if such a gap exists, the paper is pinched, which causes a paper jam. In the third method, the guide can be manufactured at a low cost, and the groove and the guide can be formed in a complicated shape. However, since the bottom of the groove is rubbed by the side edge of the sheet, there is a drawback that the durability is poor. . . SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a paper transport positioning device which is inexpensive, does not cause a paper jam, and has excellent durability.

[0004]

According to the present invention, there is provided a sheet transport positioning device, comprising: a sheet edge guide for guiding one side edge of a sheet substantially parallel to a sheet transport direction; and a position not in contact with the sheet edge guide. And a sheet conveying means for conveying the sheet located in the sheet edge guide toward the sheet edge guide. The sheet conveying means, which has a higher hardness than the sheet edge guide and projects from the sheet guide portion of the sheet edge guide toward the sheet conveying means, has a predetermined distance from each other. And at least two abrasion-resistant members substantially in line contact with the sheet to be conveyed.

[0005]

In the paper transport positioning device of the present invention, the paper is transported toward the bottom of the guide groove at an acute angle to the paper transport direction, and guided while the side edge abuts against the bottom and is positioned. The side edge of the sheet is slid on the abrasion-resistant member when the sheet is abutted or guided.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, referring to FIG. 1, the overall configuration of an image forming apparatus based on ionography using a sheet transport positioning device according to an embodiment of the present invention will be described.

A paper cassette 9 for storing unused paper sheets and detachably attached to the apparatus main body is mounted in two upper and lower tiers. A paper feed roller 13 for feeding paper is provided above the leading end of each cassette 9, and a pair of separation rollers 14 and 15 for separating paper into one sheet are provided rotatably on the apparatus body side in front of the leading end of the cassette. I have. An image carrier 2 formed of a dielectric drum is rotatably provided in the apparatus main body. Then, a recording head 3 composed of an ion cartridge for recording a latent image on the image carrier 2, a developing unit 4 for visualizing the latent image with toner, and toner on the image carrier 2 are conveyed. A corona charger 22 for transferring the image onto the incoming paper, a cleaning unit 58 for removing transfer residual toner from the image carrier 2, and the like are sequentially arranged around the image carrier 2. A registration roller 20 for transporting a sheet between the image carrier 2 and the corona charger 22, that is, a recording unit, is rotatable with respect to the apparatus main body, and the connection with the drive system can be released. It is held substantially parallel. A first paper path 59 is formed between the upper paper feed cassette 9 and the registration roller 20 by the upper surface of the guide 17 and the lower rib of the developing unit 4 located above the guide 17. . A second paper path 60 is formed between the lower sheet feed cassette 9 and the registration roller 20 by the lower surface of the guide 17 and the upper surface of another guide 18. The third paper path 61 leading to the registration roller 20 is formed by the lower surface of the guide 18 and another guide 19.
Are formed. The third paper path 61 is provided when an elevator mechanism (not shown) is attached to the apparatus main body.
The transport path of the sheet sent from this mechanism. Further, the rollers 56 and 57 of the duplex unit 8
Between the pair of rollers and the registration roller 20, the guide 19 and the right side surface of the transfer unit 6 serve as a paper guide.
A fourth paper path 62 is formed. These first to fourth
The paper paths 59 to 62 merge into one on the paper feed cassette side of the registration roller 20, and a first actuator 21 for detecting the presence / absence of paper is disposed at this portion. A vacuum fan 63 (FIG. 14) is provided downstream of the corona charger 22 in the sheet transport direction. The transfer unit 6 supports the corona charger 22, the vacuum fan 63, and the pinch roller 64 so as to move together with the rotation of the transfer unit 6. The pinch roller 64 is pressed by the registration roller 20 so that the sheet can be conveyed toward the recording unit with the sheet interposed therebetween. Further downstream of the transfer unit 6, a fixing unit 5 for fixing the toner image transferred onto the sheet to the sheet is provided. Further, the fixing unit 5
A transport unit 10 having a function of sorting the paper path is provided on the downstream side. As shown in detail in FIG. 2, the transport unit 10 is provided with first to fifth transport rollers 27 to 31 so as to be rotatable. The sheet transported from the fixing unit 5 is guided to the transport unit 10 through a fifth paper path 49 formed between the lower surface of the guide 48 and the unit 101. That is, the sheet is first guided between the second roller 28 and the first roller 27 pressed by the second roller 28. A third roller 29 is pressed against the second roller 28 on the side opposite to the first roller 27. These rollers 2
A fourth roller 30 and a fifth roller 31 for discharging paper to the sample tray 25 are disposed downstream of the rollers 7 and 28, and one roller 31 is pressed by the other roller 30. . Further, a switching gate 33 is loosely fitted to the fourth roller 30 so as to be swingable about the rotation axis of the roller. On the other hand, the second
A second actuator 32 is loosely fitted to the roller 28 so as to be swingable about the rotation axis, and can detect the presence or absence of a sheet. When the switching gate 33 is at the first lower side in FIG. 2, the fifth paper path 49 is connected to the upper surface 33 a of the switching gate 33 and the sixth paper path 49 at the downstream side of the first and second rollers 27 and 28. The paper is communicated with the paper discharge unit 11 (FIG. 1) via the paper path 50. On the other hand, when the switching gate 33 is turned to the second upper state shown in FIG.
And the fourth and fifth rollers 3 via an eighth paper path 52 downstream of the first and second rollers 27, 28.
It is communicated between 0 and 31. That is, the eighth paper path 52
Are arranged in parallel with the sixth paper path 50 with the switching gate 33 interposed therebetween.

As shown in FIG. 4, a pair of pinch rollers including a driving roller 35 and a driven roller 36 pressed by the driving roller 35 are rotatably supported on the sheet discharging unit 11. A substantially L-shaped third actuator 37 is provided on the driven roller 36 so as to be swingable about the rotation axis.
Is loosely fitted at the center with the rotating shaft. A photo interrupter 38 is provided near the actuator 37 to detect the operation thereof. These rollers 3
Reference numerals 5 and 36 can be rotated forward and backward by a drive mechanism (not shown), and have a function of discharging the paper transported from the transport unit 10 to the tray 24 at the top of the apparatus during forward rotation, and return the paper to the transport unit 10 again during reverse rotation. Has functions.
That is, at the time of reverse rotation, since the switching gate 33 is in the first state shown in FIG.
It communicates with the nip portion between the second roller 28 and the third roller 29, and further communicates with the duplex unit 8 (FIG. 1) via the seventh paper path 51.

As shown in FIG. 1, the duplex unit 8 is provided with an aligner roller 54 for feeding a sheet in a direction inclined with respect to the sheet conveying direction, and a pinch roller 55 pressed by the aligner roller 54. Further, on the downstream side of the roller 5, the above-described roller 5 provided substantially in parallel with the registration roller 20 in order to send the paper to the registration roller 20 again.
6 and a roller 57 pressed against it.
The duplex unit 8 is located almost directly below the transfer unit 6, and can be retrofitted by a user. A toner collection unit 7 is provided between the transfer unit 6 and the duplex unit 8.
Is disposed, and unnecessary toner collected from the image bearing member 2 by the cleaning unit 58 is sent to the toner collecting unit 7 and accumulated therein until the amount becomes constant.

With the above configuration, the paper feed cassette 9
From the first or second paper path 5
The sheet is sent to the nip portion between the registration roller 20 and the pinch roller 64 through 9 or 60, where it is sent to the recording section at the timing of the image, and the image is transferred by the corona charger 22. Thereafter, the toner image is fixed by the fixing rollers 26a and 26b of the fixing unit 5, is nipped by the first roller 27 and the second roller 28 through the fifth paper path 49, and is held in the first state. Guided by the guide surface 33a, which is the upper surface of the switching gate 33, through the sixth paper path 50,
Is transported to the nip portion between the normally rotated rollers 35 and 36. Then, the sheet is nipped by these rollers 35 and 36, inverted, and discharged onto the tray 24 with the recording surface facing down. Thus, one-sided recording is completed.

On the other hand, in the case of double-sided recording, the trailing edge of the paper is the first.
In addition, the second actuator 32 detects that it has passed the nip portion between the second rollers 27 and 28,
Is reversed. As a result, the paper is returned and nipped by the second roller 28 and the third roller 29, and the seventh paper path 5
1 and is led to the duplex unit 8. In this unit 8, the sheet side edge is positioned by the aligner roller 54, is reversed by the rollers 56 and 57, is again guided to the registration roller 20 through the fourth paper path 62, and is similar to the recording on the first side. The second side is recorded in the process. When the switching gate 33 is rotated to the second state as shown in FIG. 3, the switching gate 33 is guided by the guide surface which is the lower surface 33b of the switching gate 33 through the eighth paper path 52 and Fifth roller 30, 3
1 is sent to the nip portion. As a result, these rollers 3
The sheet is nipped by 0, 31 and discharged to the sample tray 25 with the recording surface facing up. Assuming that the peripheral speed of the image carrier 2 is 1, for example, the transport speed and the nip force of each roller are
The following relationship is set. Roller: Nip force (kgf); Speed ratio Circumferential speed of image carrier 2;-; 1 Transport of feed roller 13 and separation roller 14; 0.5; 3 Transport of registration roller 20 and pinch roller 64; 3; 1 1; conveyance of the first roller 27 and the second roller 28; 0.5; 1.1 conveyance of the second roller 28 and the third roller 29; 0.5; 1.7 Transport of the fourth roller 30 and the fifth roller 31; 0.5; 1.1 Transport of the roller 35 and the roller 36 during normal / reverse rotation; 0.5; 1.7 Aligner roller 54 and pinch roller 55 0.1; 5 Transport of rollers 56 and 57; 0.3; 1.7

As described above, the feeding speed of the paper feed roller 13 and the separation roller 14 is set to be about three times as fast as possible to increase the number of recordings within a certain period of time. Further, the fixing roller pair 26a and 26b and the registration roller 20
The transport speed of the image carrier is made almost equal to the peripheral speed of the image carrier.
This is to stabilize the conveyance of the sheet in the recording unit and reduce the expansion and contraction of the image. The reason why the conveying speed of the first and second rollers 27 and 28 is set to 1.1 times speed is to reduce the curl by applying tension to the sheet coming out of the fixing rollers 26a and 26b. The reason why the roller transport speed for the subsequent double-sided recording is increased is to return the sheet to the registration roller 20 again in a short time so as to increase the number of recordings within a certain time during double-sided recording. Thus, at the same time as increasing the transport speed of the rollers, the transport path for double-sided recording is shortened as much as possible.
A compact device and timeless paper transport can be achieved.

Next, a detailed configuration of the transport unit 10 will be described. As shown in FIG. 5, the second roller 28 has a horizontally extending stainless steel shaft 28e, and two stainless steel shafts 28e rotatably fitted to the shaft 28e and arranged at a predetermined interval from each other. And a plastic roller portion 28d. Rubber rollers 28c fixed to a shaft 28e are provided on both outer sides of the rollers 28d. The outer diameters of these roller portions 28d and 28c are set to be substantially the same. The shaft 28e is rotatably supported by both frames projecting from the outer cover 10a of the unit via bearings at both ends, and a reduction gear 45 is fixed at an end on the driving side outside the frame. . This second roller 2
8, the first roller 27 is pressed by a spring 47 via bearings located at both ends of the first roller 27. The roller 27 includes a stainless steel shaft 27c, two rubber roller portions 27a fixed to the shaft 27c at predetermined intervals and having the same diameter and length, and three rubber roller portions 27b having a smaller diameter and a shorter diameter. Having. These small rubber roller portions 27b are fixed to the shaft 27c so as to be located on both outer sides and between the large rubber roller portions 27a. A drive gear 44a is fixed to an end of the drive-side shaft 27c, and the drive gear 44a meshes with a small-diameter gear portion of the reduction gear 45. As a result, the large rubber roller portion 27a and the roller portion 28d are pressed against each other by the force of the spring 47, and the small rubber roller portions 27b and the roller portions 28c on both sides are pressed.
There is a gap between them. The center-to-center distance between the drive gear 44a and the reduction gear 45 is set wider than the regular distance. As a result, the force of the spring 47 is not affected by the gears, and all of the large rubber roller 27a and the roller 28d
And the nip pressure. On the other hand, the third roller 29 is also pressed toward the second roller 28 by a spring 47 via bearings at both ends. The third roller 29 is composed of two plastic roller portions 29a and one plastic roller portion 29b coaxially fixed to a shaft 29c thereof.
a is pressed by the rubber roller portion 28c. When the reduction gear 45 is rotated by this mechanism, the second roller 28 rotates, and the third roller 29 is driven by the nip pressure between the plastic roller portion 29a and the rubber roller portion 28c. At the same time, the first roller 27 is driven at a lower rotational speed than the second roller 28 due to the reduction ratio between the reduction gear 45 and the drive gear 44a. Since the roller portion 28d of the second roller 28 is driven by the large rubber roller portion 27a, it rotates in the same direction as the shaft at a low rotation speed. Therefore, the small rubber roller portion 27a and the roller portion 28d
Assuming that the transport speed of the paper nipped in the above is 1, the speed of the paper nipped and transported by the rubber roller portion 28c and the roller portion 29a increases, for example, to 1.7 as described above. can do. The fourth roller 30
Are rotatably fixed to the frame of the outer cover 10a of the unit by bearings at both ends of the shaft 30e. The shaft 30e has a gear 44b on the drive side outside the frame.
However, near the center, a rubber roller portion 30d of the same diameter
Each is fixed. The fifth roller 31 has both ends of the shaft 31b pressed in the direction of the fourth roller 30 by a spring 47 via bearings. This roller 31
Has two plastic roller portions 31a fixed to a shaft 31b, and these roller portions 31a are rubber roller portions 3a.
0d. The portion of the plastic roller portion 31a where the nip is not nipped, that is, the outer end portion, has a large diameter, and functions to make the paper stiff. And FIG.
As shown in FIG. 5, the small-diameter gear portion of the reduction gear 45 fixed to the third roller 28 is provided with a drive train from there via a gear train composed of two idler gears 46 so as to receive the driving force.
A gear 44b fixed to the fourth roller 30 is gear-connected. Thus, a drive system of the transport roller having the speed reduction mechanism is configured. Next, the second actuator 32 for detecting a sheet will be described with reference to FIGS.

This actuator is made of a synthetic resin molded integrally, and has a shaft 28e of the second roller 28.
Two small-diameter portions 28 formed at a predetermined interval from each other
a, 28b (FIG. 5) is supported by being able to swing around the roller 28 by pushing and expanding a bearing part whose outer periphery has been partially cut. A metal weight 32d is inserted and fixed below the actuator 32. Further, the arm portion 3 of the actuator 32 extending upward and downward so as to actually contact the sheet.
2a and 32b are a first roller 27 and a second roller 28
Tangent to the second roller 28 and the third roller 2
9, and its tip is located downstream of the nip point in the sheet conveyance. Therefore, only the leading edge of the sheet securely nipped between these rollers pushes the actuator 32, and the actuator 32 is weighted by the weight 32d.
Is rotated about the second roller 28 against the weight of the second roller 28. The actuator 32 is provided with a light-shielding portion 32c having a function of shielding light.
2c is when the sheet is not detected, that is, when the sheet is between the first and second rollers 27 and 28, or when the second and third rollers 2
When it is not between the positions 8 and 29, as shown in FIG. 6, the photo interrupter 38 comes into contact with the moment of the weight 32d to block the optical axis of the photo interrupter 38. Then, the leading end of the paper nipped by the roller is moved to the arm portion 32a or 3d.
When the user presses 2b, the light shielding portion 32c is rotated counterclockwise in FIG.
Is released, and paper can be detected. With such a configuration, it is possible to detect a sheet in different paper paths conveyed in different directions by using one actuator 32 and the photo interrupter 38 in a compact space without providing a new holding member for the actuator 32. I have. Next, the switching gate 33 will be described.

The switching gate 33 is formed by integral molding of the mold, and as shown in FIG.
At the positions corresponding to the small-diameter portions 30a, 30b, and 30c, respectively, have a bearing portion with a part of the outer periphery cut out. It is fitted so as to be swingable about 30e. Then, a boss 33c provided at the drive side end of the switching gate 33 protrudes out of the frame of the outer cover, and fits into a hole 41a (FIG. 8) formed on the upper part of the stainless steel link 41. ing. The link 41 is engaged with the plunger of the solenoid 40 by a U-shaped groove 41b formed at the lower end, and is attached to the plunger by a tension spring 42 spanned between a hole 41c formed at the upper end and the frame. It is biased in the direction opposite to the biasing direction. This hole 41
a, the U-shaped groove 41b, and the hole 41c are formed so as to be substantially aligned. Thus, when the solenoid 40 is turned on, the switching gate 33 is
Rotates downward about the axis of the fourth roller 30 to be in the first state shown in FIG. 8 (the state shown in FIG. 2). On the other hand, when the solenoid 40 is turned off, the link 41 moves upward by the urging force of the spring 42, and the switching gate 33 rotates to the second state (the state shown in FIG. 3). This link 41
Is determined by the position of the solenoid 40 and the position of a stopper (not shown) for the link 41.

As described above, the switching gate 33 is connected to the fourth gate.
By rotating the tip in the vicinity of the first, second and third rollers 27 to 29 around the axis of the roller 30,
There is no need to provide a new center of rotation and the switching gate 3
3, a function to guide the paper in the direction of the paper discharge unit 11, a function to guide the paper from the paper discharge unit 11 to the duplex unit 8, and a paper to guide the paper from the paper discharge unit 11 to the sample tray 25. With the ability to
By providing the functions of three paper guides, a compact device can be provided. Next, the guide film 34 will be described with reference to FIGS.

A guide 48 is mounted on the sheet discharging unit 10 so as to be thermally expandable in a direction perpendicular to the sheet conveying direction. The guide 48 having such thermal characteristics is used in order to prevent the guide from thermally expanding in the sheet transport direction due to the heat of the sheet heated by the fixing roller 26, thereby preventing the sheet from being disturbed. It is. This guide 48 is
8a is a paper guide surface, and one end of a guide film 34 is fixed to the upper surface with an adhesive. Since the guide film 34 is provided near the fixing roller 26, it is required to have heat resistance (melting point of 70 ° C. or more), and is required to have abrasion resistance because it is worn by friction with paper. Therefore, in this embodiment, a polyimide sheet having a thickness of 200 μm and a width of 10 mm is used. The guide film 34 includes first and second rollers 27, 2
The sheet passes through the non-nip portion between the rollers 8 and abuts the switching gate 33 by its elastic force, extends in the direction of the sixth paper path 50, and has an end protruding out of the paper path through a hole 102 provided in the unit. The protruding end is not fixed, and the width is set to be larger than the width of the hole 102 so that the sixth paper path 5
The end is prevented from entering the inside of 0. In order to make the apparatus compact, first to third rollers 27 to
The diameter of 29 is designed to be small (about 12 mm in this embodiment). When such a small-diameter roller is used, if there is a curl at the rear end of the paper, the paper that has escaped from the fifth paper path 49 to the sixth paper path 50 is rotated in reverse by the rollers 35 (FIG. 4) of the paper discharge unit 11. This makes it difficult to accurately enter the nip portion between the second and third rollers 28 and 29.
For this reason, the guide film 34 functions to reliably guide the paper to the seventh paper path 51 by pressing the vicinity of the rear end of the paper against the switching gate 33 with its elastic force. The effect of the guide film 34 increases as the guide film 34 protrudes near the tip of the second roller 28 and the switching gate 33. At this time, the first paper path from the fifth paper path 49 side does
Is provided between the first roller 27 and the second roller 28. Since the interval between the two rollers 27 and 28 is narrow, the guide film 34 is formed of a thin sheet material so as not to interfere with the axis of the roller 27. The reason why one end of the guide film 34 protrudes out of the sixth paper path 50 is to prevent the thin guide film 34 from being damaged in the processing in the event of a paper jam. Further, the guide film 34
Is made of a thin sheet material, so that even when the switching gate 33 rotates, the upper surface 33 a pushes the guide film 34 as shown in FIG. 3 to form the eighth paper path 52, and the paper is discharged to the sample tray 25. Becomes possible.

The timing at which the roller 35 provided in the paper discharge unit 11 switches between the normal rotation and the reverse rotation is important. The first-recorded sheet conveyed from the fifth sheet path 49 is first and second rollers 27 and 28.
And the roller 35 must be rotated in the reverse direction after the trailing edge of the sheet has passed the nip portion without fail.
If the reverse rotation is too early, a paper jam occurs, and if the reverse rotation is too late, wasteful time is required for the movement of the paper. In the present embodiment, the light-shielding portion 3 passes through one arm 32a of the second actuator 32 having the above-described configuration when the rear end of the sheet passes.
The nip of the first and second rollers 27 and 28 is ensured by setting the timing at which the optical axis 2c interrupts the optical axis of the photointerrupter 38 (FIG. 6) or the sequence in which the roller 35 is reversed after a predetermined time T1 described later. Can be conveyed in the reverse direction at the timing when the trailing edge of the sheet has passed and with minimal waste of time. Also,
The reversed sheet is nipped by the second and third rollers 28 and 29 in the normal conveyance state, and is again moved by the actuator 3.
Since the optical axis of the photo-interrupter 38 is interrupted for a certain time by the light-shielding portion 32c by pressing the other arm portion 32b of the second device 2, by detecting this, it is possible to know that the paper has been conveyed to the seventh paper path 51 without fail. Can be. Therefore, even if a sheet is not conveyed to the seventh sheet path due to some kind of paper jam, this can be detected promptly, and failure or damage of the apparatus can be prevented. Next, the above-described paper discharge unit 11 shown in FIG. 4 will be described in detail.

The driven roller 36 of the paper discharging unit 11
Are pressed by a spring (not shown) toward the center of the drive roller 35 via a bearing and pressed against the drive roller 35, and follow the rotation of the roller 35. And this roller 36
A small-diameter portion is formed substantially at the center of the stainless steel rotary shaft, and an L-shaped third actuator 37 is fitted by pushing and expanding a bearing portion having a partially cut outer periphery, and is rotatably loosened. Mated. One arm 37d of the actuator 37 has an arc shape, and the tip 37a protrudes toward the tray 24. The tray 24 is inclined so that the sheet discharging unit 11 side is lower as shown in the figure. The lower surface of the arm portion 37d directly contacts the leading edge of the sheet, but its arc shape is set so that the angle with the leading edge of the sheet is always small. A metal weight 3 is located near the tip of the actuator 37.
7b, and the moment of the weight 37b causes the other arm portion 37c, which is a light shielding portion, to be in contact with the photointerrupter 38. At this time, the optical axis of the photointerrupter 38 is blocked by the light blocking portion 37c, and it is detected that there is no paper. A sheet is conveyed from the conveyance unit 10 through a sixth paper path 50 by a nip portion of first and second rollers 35 and 36,
One arm 37d of the actuator 37 at the leading end of the paper
When the actuator 37 comes into contact with the lower surface of FIG.
During the rotation, the light blocking unit 37c is rotated counterclockwise to separate the light blocking unit 37c from the optical axis of the photo interrupter 38, and detects that a sheet has arrived. Thereafter, when the trailing edge of the sheet leaves the rollers 35 and 36 and the sheet falls into the tray 24, the actuator 37 returns to the state shown in FIG. 4 again by its own weight (by the action of the weight 37b), and the photo interrupter 38 The optical axis is blocked. If this operation is repeated each time a sheet is conveyed, the recorded sheets are sequentially stacked on the tray 24. And
When a predetermined number of sheets are stacked on the tray 24, the leading end 37a of the actuator 37 rides on the stacking paper upper surface 23, the actuator 37 is rotated counterclockwise, and the optical axis of the photo interrupter 38 is blocked. Disappears. If the optical axis of the actuator 37 is not interrupted for a certain period of time during the discharge operation during a period in which a plurality of sheets are discharged, it is determined that the stacked sheets on the tray 24 are full and a new paper feed operation is performed. At the same time, the setting is set so that the full sheet information is sent to a panel (not shown) so that the operator can recognize this state. This paper feeding operation is prohibited for tray 2
The recorded paper on 4 is removed by the operator's hand, and is released when the optical axis of the photo interrupter 38 is shielded by the light shielding portion 37c of the actuator 37, and the information on the panel is also erased. This third actuator 37
Only the full sheets of the stacked paper on the tray 24 are detected, and when a sorter described later is not mounted, a paper jam due to paper traveling is not detected. This is to prevent the erroneous information of a paper jam from being output when the actuator 37 is erroneously touched from outside the apparatus. As in the present embodiment, the third
By mounting the actuator 37 on the shaft of the driven roller 35, no new holding member is required, and the full paper detection mechanism can be configured compactly. Further, the actuator can pass from the upstream side to the downstream side of the nip portion between the rollers 35 and 36, and is conveyed by making one of the arm portions 37d into an arc shape and the tray 24 having an inclination. The contact angle with the incoming paper is always kept small, so that it is possible to form the paper into a shape that does not damage the leading end of the paper.
The length of the upward projection can be reduced. As a result, when the operator removes the sheets stacked on the tray 24, the actuator 37 does not interfere.

FIG. 9 shows the second actuator 3 described above.
The operation timing of the second and third actuators 37 is shown. When the second actuator 32 repeatedly outputs ON and OFF during the predetermined operation time T1, it is detected that there is no paper jam in the transport path to the actuator 32. If the next detection signal is not detected even after the predetermined time T1, it is determined that a paper jam has occurred. The third actuator 37 detects the front end of the sheet after a lapse of a predetermined time T2 from the detection of the front end of the sheet by the second actuator 32 (that is, T2 is the second end).
(Corresponding to the paper movement time from the second actuator 32 to the third actuator 37), and the second actuator 3
2 detects the trailing edge of the sheet when the sheet is not detected. The third actuator 37 is operated for a predetermined time (T3 +
T4) If the detection signal continues to be output even after the lapse of time, it is determined that the tray 24 is full.

As shown in FIG. 10, a sorter 16 or the like can be optionally mounted on the apparatus. This sorter 16 conveys the fed paper upward by an endless belt, except for a switching gate 33 shown below, and sorts and discharges the paper sequentially to a plurality of trays arranged vertically. Because it is a well-known configuration,
The description is omitted. The switching gate 39 is for selectively switching the paper path between the tray 24 and the sorter 16, and when the sorter 16 is mounted on the apparatus,
It is located above the tray 24 and near the rollers 35 and 36. The switching gate 39 is rotatably provided on the sorter main body around a shaft 39a, and the position of the distal end 39b of the roller 3 is adjusted by a driving mechanism (not shown).
The position is selectively switched between a position below the nip tangent line 5 and 36 (the position shown in FIG. 10) and a position above the nip tangent. The switching gate 39 has a central portion facing the third actuator 37 cut away as shown in FIG. 11, into which one arm portion 37a of the actuator 37 can be inserted. Therefore, the actuator 37 and the switching gate 39 are wrapped in a skewer shape so as not to interfere in the operation range. Even if sheets are stacked on the tray 24 in a full state, the switching gate 39 is set at a position where the stacked sheets do not interfere with each other.
Whether the paper is sent to the sorter 16 or discharged to the tray 24 is determined based on a command from the host computer.
When the paper is sent to the sorter 16, as shown in FIG. 10, while the paper is passing, the actuator 37 is rotated counterclockwise to lift the leading end 37a and release the interruption of the optical axis of the photo interrupter 38. Is done. When the sheet passes through the actuator 37, the actuator 37 returns to the original position as described above, and the photo interrupter 38 is cut off the optical axis. At this time, that is, when the sorter 16 is used, the photo interrupter 38 uses the actuator 37 not for detecting the full sheet but for detecting the passage of the leading end or the trailing end of the sheet. Therefore, it is not necessary to newly provide a paper detection sensor in the sorter 16. When the paper is discharged onto the tray 24, or when a part of the paper is once put out onto the tray 24 in the double-sided recording mode and the roller 35 is rotated again to feed the paper into the apparatus, the switching gate is used. Reference numeral 39 slightly rotates clockwise in FIG. 10 to move the distal end 39 b to a position on the arm 37 d of the actuator 37. With such a configuration, it is possible to cope with a case where the entire length of the paper to be recorded on both sides is long and a long portion is to be put on the tray 24 from between the rollers 35 and 36, as in the case where the sorter 16 is not attached. Has become. Further, even when the sheet is discharged onto the tray 24, the actuator 37 can be used for detecting the full sheet as in the case where the sorter 16 is not provided. That is, when the sorter 16 is mounted, if the optical axis of the photo-interrupter 38 is not interrupted by the timing of no paper while the sheet is being discharged to the tray 24, a new sheet for recording to be sent to the sorter 16 is used. Such a paper feed is immediately prohibited, and the prohibition is canceled when the paper on the tray 24 is removed and the optical axis of the photo-interrupter 38 is cut off. As a result, when the paper is sent to the sorter 16, the actuator 37 is used to detect the leading and trailing edges of the paper, and when the paper is discharged to the tray 24, it is used to detect the full paper. Since the sorter 16 is not provided with a new sheet detecting mechanism, the communication of the sorter 16 with the apparatus main body can be simplified. In addition, the optional sorter 16 and the standard tray 24 are arranged vertically, and the sorter 16 can be mounted while utilizing the full-sheet detection mechanism and the paper storage function of the tray 24.

In this embodiment, the sorter 16 can be mounted while the function of the standard tray 24 is maintained, and the switching gate 39 is provided on the sorter 16 side. Thus, for example, even if the standard tray 24 becomes unusable without the switching gate 39, the actuator 3
If the sorter 16 is used when the sorter 16 is mounted and the sorter 16 is not mounted and the method of use is simply switched to detect the fullness of the stacked paper on the tray 24, no new paper detection mechanism is required on the sorter side. Is effective. Full paper detection when the sorter 16 is not installed,
The paper detection operation when the sorter 16 is mounted will be described with reference to FIG.

When the power supply P is turned on, it is determined whether or not the detection signal from the third actuator 37 is Off (S).
1). In the case of No, the sheet feeding operation is prohibited (S2), and a display indicating that the sheet is full is displayed. On the other hand, in the case of Yes,
The counter C is set to the initial state (K = 0), and it is determined whether the sheet feeding to the sorter 16 is set (S3). In the case of No, the switching gate 39
Is maintained at the upper position (S4). When the sheet feeding is started and the detection signal is output from the second actuator 32 (S5), the counter B is set to the initial state (J = 0).
Then, the counter C is turned on, and this constant (J = J +
When 1) is counted (S6), it is determined whether or not the detection signal from the third actuator 37 is Off (S6).
7). In the case of Yes, when the time set by the count J becomes longer than the time (T3 + T4; see FIG. 9) (S8), the counter B is turned off (S9). On the other hand, if the result of step 7 is No, the counter C starts counting (K = K + 1) (S10), and compares the count number K with the set value M (S11). When B is turned off and K becomes larger than M, the paper on the tray 24 is full, and the paper feeding operation is prohibited (S2).

The paper is discharged to the tray 24 as described above. On the other hand, if the discharge to the sorter 16 is set (Yes in step 3), the switching gate 3
9 is turned on and turned to the lower position as shown in FIG. After this, the count J of the counter C is T3 + T4
If it is longer than the above, the paper is discharged in the same step as the paper discharge to the tray 24 except that the paper jam is detected. Next, the transfer unit 6 will be described.

The transfer unit 6, as shown in FIG.
It is provided on the back side of the plastic body molded integrally with the mold.
Two bosses 601 (only one is visible in the figure) horizontally separated from each other are held in a frame 68 of the apparatus main body so as to be rotatable in the vertical direction. The front side of the plastic body is hooked on the unit 1 with a hook (not shown), and as shown by a solid line,
It is held substantially horizontally (horizontal position). By removing the hook, the operator swings the transfer unit 6 from the horizontal state to the state in which the front side is lowered by its own weight (inclination position), indicated by the two-dot broken line, around the boss 601 on the rear side. Is possible. The transfer unit 6 has a guide portion 602 formed on one side to form a paper path for guiding the paper to the registration roller 20 as shown in FIG.
The corona charger 22, the pinch roller 64, and a mechanism for pressing the pinch roller 64 against the registration roller 20, the corona charger 22 and the pinch roller 6
Guide portion 6 formed to form a lower side of the paper path between
03 parts are provided. Further, a fan 63 for sucking the transferred paper and bringing it into close contact with the transfer unit 6 side is held at the upper part. Therefore, when the transfer unit 6 is maintained at the horizontal position, the pinch roller 64 presses the registration roller 20 horizontally, and
And works to convey the paper. The corona charger 22 is located on the lower side near the image carrier 2, and
A function 03 guides the sheet and guides the sheet between the image carrier 2 and the corona charger 22. When the operator rotates the transfer unit 6 to the inclined position, the transfer unit 6
It turns by 6.5 degrees and abuts on a frame (not shown) to be fixed. In this state, the front side is opened along the paper path, that is, the lower surface of the transfer unit 6 at the horizontal position and the Ducles unit 8 at the horizontal position described later.
Processing space (processing space) 7 regulated between the upper surface of
Through the holes 0 and holes 69 formed in the front part of the frame 68, it is possible to remove jammed paper on the transfer unit 6 and to replace a corona charger which is a regular replacement part. Next, the toner collecting unit 7 will be described.

The toner collecting unit 7 is mounted in a processing space 70 regulated between the transfer unit 6 and the Ducles unit 8 as shown in FIG. As shown in FIGS. 15 and 16, the toner collection unit 7 includes a bottle holder 71 made of sheet metal and a bottle 72 made of plastic and serving as a storage member for actually storing toner.
It is composed of Since the bottle 72 is periodically replaced or the toner therein is discarded, the bottle 72 is disposed between the mounting portions 71c and 71d projecting upward so as to face the bottle holder 71 at a predetermined interval. Are fitted using the elastic force of the two, and both are detachably integrated. The bottle holder 71 is provided with a bent portion 71 formed on a stay portion extending from the front side to the rear side of the frame 68.
b is slidably held along this. When the toner recovery unit 7 is mounted at the operating position,
The mounting portion 71a is positioned by fitting with the frame 68 (FIG. 15), and the bottle 72 is disposed at the rear (second position) of the processing space 70. The residual toner collected by the cleaning unit 58 (FIG. 1) is passed through a not-shown gut (toner conveying means) on the rear side and is stored in the bottle from an opening 72b of the bottle 72. The bottle holder 71 can be pulled out to the front side as shown in FIG. 16 up to a position where the protruding portion 71e contacts the frame 68,
At this position (first position), the bottle 72 is placed in the bottle holder 7.
1 is attached and detached. That is, the remaining toner can be stored in the bottle 72 with the toner collection unit 7 inserted in the rear side, and the bottle 72 can be replaced with the bottle 72 pulled out in the front side. In addition, when the transfer unit 6 is turned to the inclined position in the mounting position, as shown in FIG. 17, the bottle 72 is positioned at the rotation center side (rear part) so as not to hinder the rotation. And the upper surface front portion 72a
Is inclined. Next, the duplex unit 8 provided with the sheet transport positioning device of the present invention will be described.

As shown in FIG. 14, the duplex unit 8 is provided on the bottom of the apparatus with a processing space 70 therebetween so as to be located immediately below the transfer unit 6 and the toner recovery unit 7. As shown in FIGS. 1, 14, and 20, the duplex unit 8 is driven by the roller 56 intermittently driven from the apparatus main body via the clutch 85 in parallel with the roller 56. And a roller 57. These roller pairs 56 and 57
Are arranged in parallel with the registration roller 20. The driven roller 57 is supported at the rear by a rotating shaft 81 extending in parallel with the rotating shaft of the transfer unit 6, and is supported by a paper guide body 82 provided rotatably around the rotating shaft 81. By lifting the paper guide body 82, the nip with the roller 56 is released. This paper guide body 82
The paper guide 8 has a part on the front side that spreads substantially horizontally in a plane toward the aligner roller 54 and faces the lower surface.
The upper surface of the roller 4 guides the leading edge of the sheet to the nip of the rollers 56 and 57. Further, the paper guide 84 extends so as to be curved upward toward the upstream side, and receives the rotational force of the roller 56 via the pulley 86 and the belt 87 at this extended portion. And inclined in the direction in which the paper is transported backward with respect to the paper transport direction (5 to 5).
An aligner roller 54 attached at 20 °),
A pinch roller 55 which is pressed in parallel with and driven by the pinch roller 55 is rotatably mounted (FIG. 14). Accordingly, the aligner roller 54 is driven and rotated simultaneously when the roller 56 is driven. A groove 83 for positioning the rear edge of the paper is integrally molded with the paper guide 84 formed by integral molding of a synthetic resin along the transport direction.
That is, the groove 83 is formed on the guide rib surface 84a of the paper guide 84.
A protruding rim 82b located above is formed on one side, a groove bottom 83b is formed at right angles to the paper side edge receiving portion 84b, and the longitudinal direction is formed along the transport path. This groove 83 has a width (vertical direction) of 1 to 2 mm,
The depth of the groove is 10 mm, and the bottom of the groove is parallel to the rear edge of the sheet at the time of the transfer of the first surface when viewed in the sheet conveyance direction and is positioned 2 mm behind. That is, with respect to the fifth and sixth transport paths 49 and 50 for transporting the sheet immediately after the first surface is recorded,
In the transport path defined by the groove 83, the latter is shifted backward by 2 mm (toward the paper surface in FIG. 1 and to the right in FIG. 15). The groove 83 also extends upwardly along the guide rib surface 84a of the paper guide 84 toward the aligner roller 54 along the guide rib surface 84a, and guides one side edge of the paper according to this shape.

The one-side recorded paper which has been inverted by the paper discharge unit 11 and conveyed to the duplex unit 8 through the transport unit 10 and the seventh paper path 51 is
One side is guided by the groove 83, and the lower surface is supported by the guide rib surface 84 over the entire width, and is conveyed to the nip portion of the rollers 56 and 57 by the aligner roller 54. At this time, the conveying force of the aligner roller 54 is equal to the second and third rollers 28,
Since the conveyance force is set smaller than the conveyance force of the sheet 29 and the conveyance speed is set to be high, the sheet slips on the sheet while the rear end of the sheet is nipped by the rollers 28 and 29, and the rear end of the sheet is At the point of time after passing the nip 29, the sheet is conveyed toward the rollers 56 and 57 while being shifted at the conveying speed of the aligner 54 toward the bottom of the groove 83 which is the conveying direction of the aligner roller 54. As a result, the paper
The rear end is positioned at the bottom of the groove 83 and the roller 5
6 and 57, and guided by the guide 19 and the guide portion 602 of the transfer unit 6, and
Transported to At this time, since the transport speed of the aligner roller 54 is faster than the transport speed of the roller 56, after the leading edge of the sheet is nipped by the rollers 56 and 57, the sheet rotates while slipping on the sheet. However, the conveying force of the aligner roller 54 is weak, the rear edge of the sheet is guided between the upper and lower surfaces of the narrow groove 83, and the groove 8
3 and the effect of the paper guide 84 being curved,
Even thin thin paper can be transported without buckling. When the leading edge of the paper reaches the registration roller 20, the rotation of the registration roller 20 is stopped. The leading edge of the paper is detected by the first actuator 21, and the leading edge of the paper is applied to the nip point between the pinch roller 64 and the registration roller 20. After the loop is formed, the driving of the roller 56 is stopped by the clutch 85. In this state, since the guide 19 is curved, there is no space for the paper to buckle and form a loop, so that the loop formed here is very small. Next, the registration roller 20 is driven again in synchronization with the image on the image carrier 2, and the sheet is conveyed to transfer the second surface. The roller 56 is driven by 85 to feed the trailing edge of the sheet toward the registration roller 20. Although the transport speed of the roller 56 is faster than that of the registration roller 20, the paper buckles due to the curved fourth paper path 62 and the effect that the transport force of the roller 56 is small and slips on the paper. Without the registration roller 20
Transported at a speed of With such a sequence, registration of a sheet and an image can be reliably performed even in a sheet path where only a minute loop can be formed. Further, the load on the roller 56 at a position where the conveyance direction is different from that of the registration roller 20 is reduced to reduce the load on the registration roller 20.
Can be reliably transported. In the transfer of the second surface, the sheet is at a position shifted by 2 mm deeper than the first surface due to the positioning of the groove 83. In accordance with this, the image on the image carrier 2 by the recording head 3 is also 2 mm.
The image is shifted and recorded in the horizontal direction (the direction perpendicular to the transport direction).

In this embodiment, the groove 83 is formed by integral molding of the mold.
By forming the paper guide 84 having the shape, an inexpensive and complicated shape is made possible. However, in the case of synthetic resin, the bottom of the groove 83 is worn by the rear edge of the paper, which makes it impossible to position the paper or causes paper jam. To solve this problem, a cylindrical pin 88 made of stainless steel is press-fitted into the bottom of the groove 83 (FIG. 19). These pins 88 extend substantially perpendicular to the direction in which the grooves extend,
The pin is inserted and fixed to the paper guide 84 so that the most protruding portion of the outer peripheral surface is flush with the downstream portion 83 a of the bottom surface of the groove 83. Each of the pins 88 is arranged one by one on the upstream side and the downstream side in the paper transport direction from the transport position of the aligner roller 54. Then, as shown in FIG. 19A, the downstream groove bottom portion 83a is separated from the downstream pin 88 by a boundary.
The upstream groove bottom portion 83b is made deeper, and
3b does not contact the paper. When the sheet is being conveyed only by the aligner roller 54, these two pins 88 receive a rotational moment generated on the sheet by the conveying force of the aligner roller 54 and the resistance of the paper path. When the trailing end of the sheet comes off the pin 88 on the upstream side, the leading end of the sheet is already positioned and conveyed by the rollers 56. However, only the trailing edge of the paper rotates, and the groove bottom 83
When it comes into contact with b, abrasion occurs at the bottom and the paper trailing edge is caught in the groove created by the abrasion, causing paper jam.
The bottom portion 83b is at a position where it has been released by a predetermined distance (l) so as not to contact the paper. In this embodiment, l = 0.5 mm
And The rotation of the paper varies depending on the number, nip width, and shape of the aligner rollers 54, but at least if a metal pin is provided on the paper transport direction upstream from the center of gravity of the paper when the paper starts moving in the direction of the groove 83, The present invention is effective not only in the present embodiment but also in preventing wear of the groove bottom. When the aligner roller 54 is set upstream of the center of gravity of the sheet as in this embodiment, it is more effective to provide the pins further upstream than the aligner roller 54. In this embodiment, since the paper guide 84 has a curved shape, even a slightly curled paper is conveyed along the paper guide 84, and the rear edge is formed by the groove 83.
Therefore, the paper path 82 can be formed by simply extending the paper guide 82 to guide the other side. Therefore, even in the event of a paper jam, the paper guide body 82 can be easily processed by opening the paper guide body 82 upward around the opening / closing center 81. In the above embodiment, a stainless steel pin was used as the wear-resistant member, but the material and shape are not limited to this. That is, any material may be used as long as it has higher hardness than the paper guide. Further, as for the shape, it is preferable that the surface that comes into contact with the paper has an arc shape so as to make substantial line contact with the paper. Below, the recording head (ion cartridge)
The third drive circuit will be described with reference to FIG.

An output side of a raster image processor (RIP) 100 for transmitting a video signal in byte units is connected to a buffer unit 102 via an interface (I / F unit) 101. Also, this I / F unit 101
Is connected to one output side of a CPU 103, and the CPU 103 is connected to a side registration setting unit 104. A one-side recording switch 105 and a two-side recording switch 106 are connected to the side registration setting unit 104. These switches 105 and 106 are provided on an operation panel (not shown) of the apparatus main body, and are selectively operated by a user. When the single-sided recording switch 105 is selected, and when the single-sided recording switch 106 is selected and one side is recorded, the CPU 103 drives the buffer unit 102 with a predetermined command to output a normal recording signal. Then, the buffer unit 102 is driven via the side registration setting unit 104 so as to output a shift recording signal described later when the double-sided recording switch 106 is set and recording on the other side is performed. The side resist setting unit 104
Is connected to the input side of the buffer unit 102. The output side of the buffer unit 102 is provided with a deskew unit 107 for converting the recording signal sent from the buffer unit 102 into a matrix recording signal so as to be a drive signal for the finger electrode and the ion electrode of the recording head 3.
It is connected to the. The output side of the deskew unit 107 is connected to an ion cartridge (ICG) driver 108, and the ion cartridge (ICG) 3 is driven by a driving high voltage signal based on a recording signal from the deskew unit 107.

The image carrier 2 is provided with an encoder 110 for detecting the number of rotations of the image carrier.
Is output via the timing generation unit 111
The recording signals are input to the I / F unit 101, the buffer unit 102, and the deskew unit 107 and output at predetermined timings. That is, the double-sided recording switch 1
When 06 is selected, the other side recording timing is set.

The recording head 3 has 2532 dots, of which 2456 dots are used for actual recording, leaving room for 32 dots on both sides. And
In the case of single-sided recording, white data of 5 bytes, that is, 40 dots, is added to the head of the recording signal of each recording line.
On the other hand, in the case of the other side recording, the CPU sets the white data to be 64 dots. Therefore, the recording signal of each recording line is shifted backward by 64-40 = 24 dots. Since the recording head is set to record 12 dots in 1 mm, recording shifted in the horizontal direction by 2 mm (24 dots) is eventually possible. Next, the relationship between each unit and the frame 68 will be described.

The frame 68 is made entirely of a plastic integral molding, and has a large hole 69 on the front side. Through this hole 69, the process unit 1,
The developing unit 4, the fixing unit 5, the transfer unit 6, the toner collecting unit 7, the duplex unit 8 and the like can be operated or detached. The transfer unit 6 and the duplex unit 8 are substantially opposed to each other, and the toner collecting unit 7 is located behind the processing space 70 therebetween. Since the toner recovery unit 7 is disposed on the rear side, even if the front side of the transfer unit 6 is lowered, it does not interfere with the toner recovery unit 7. Further, since only the front side of the transfer unit 6 is planar as shown in FIG. 17, the transfer unit 6 does not interfere with the toner recovery unit 7. Since the transfer unit 6 and the duplex unit 8 are opposed to each other across the processing space 70, the transfer unit 6 and the duplex unit 8 can be opened and closed alternately in the same space. As a result, when a paper jam occurs, the processing space 70 is used as a space for lowering the transfer unit 6 to remove the paper (FIG. 13) or raising the paper guide body 82 to remove the paper (FIG. 20). That is, since the rotation ranges of the transfer unit 6 and the duplex unit 8 in the space 70 overlap, the space can be reduced as compared with the case where the moving spaces for both are formed independently. . Also, when the corona charger, which is a consumable, is exchanged, it is used as a space for lowering the transfer unit 6. Further, when the bottle 72 is replaced, it is used as a space for drawing out the toner collecting unit. Since these use states do not occur at the same time, one space can be used for multiple purposes, thereby realizing a compact apparatus. In addition, as compared with the transfer unit 6, the position of the paper guide body 82 in the vicinity of the frame hole 69 is located on the back side of the apparatus (see FIG.
0), that is, since the total length of the paper guide body 82 is set shorter than the entire length of the transfer unit 6, the transfer unit 6 can be opened at a larger angle. Also, the paper guide body 82 can be opened at a larger angle.
Of course, the entire length of the transfer unit 6 may be set longer than the entire length of the paper guide 82.

Next, a description will be given of the paper jam removal of the transport unit 10 part. As shown in FIG. 21, the transport unit 10 is integrally held with the outer cover 10 a and is held openably and closably about a rotation center 65 with respect to the apparatus main body.
It is possible to rotate 45 degrees. As a result, in the opened state, it is possible to open all of the fifth paper path 49, the sixth paper path 50, and a part of the seventh paper path 51 at the same time. In this embodiment, the paper path for discharging the paper to the tray 24 and the paper path for reversing the paper are shared by the sixth paper path 50, and the path length from the sixth paper path 50 to the seventh paper path 51 is the paper length. Because it is sufficiently shorter than this, there is no distinction between single-sided recording unit and double-sided recording unit,
The paper jam can be cleared simply by opening the transport unit 10. Also, in the case of paper discharge to the sample tray 25, the fifth
Since the distance from the paper path 49 to the sample tray 25 is shorter than the length of the paper, a part of the paper always appears by opening the transport unit 10. As a result, processing can be performed by opening the transport unit 10 even when the sheet is discharged to either the tray 24 or the sample tray 25.

[0035]

In the paper transport positioning apparatus according to the present invention, a paper guide body having a guide groove substantially parallel to the paper transport direction and guiding one side edge of the paper is formed by integral molding of a synthetic resin. Therefore, it can be formed at low cost and without the risk of paper jam. A wear-resistant member having a hardness higher than that of the paper guide is provided at at least one position at the bottom of the guide groove, thereby guiding the paper guided to the guide groove for positioning. Excellent in nature.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating an entire image forming apparatus including a sheet transport positioning device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating the transport unit of the image forming apparatus in a state where a switching gate thereof is located at a lower position.

FIG. 3 is a view showing the transport unit of the image forming apparatus in a state where a switching gate thereof is at an upper position.

FIG. 4 is a diagram illustrating a paper discharge unit of the image forming apparatus.

FIG. 5 is a diagram illustrating a transport roller speed reduction mechanism of the transport unit shown in FIG. 3;

FIG. 6 is a diagram illustrating a drive system of a transport roller of the transport unit illustrated in FIG. 3;

FIG. 7 is a front view showing a switching gate of the transport unit shown in FIG. 3 together with a driving mechanism thereof.

8 is a front view showing a switching gate of the transport unit shown in FIG. 3 together with a drive mechanism thereof.

FIG. 9 is an explanatory diagram of output signals of a sensor by second and third actuators used in the image forming apparatus.

FIG. 10 is a diagram illustrating the sorter and a sheet discharging unit when the sorter is mounted on the image forming apparatus.

FIG. 11 is an exploded perspective view for explaining a positional relationship between a switching gate of the sorter and an actuator of a sheet discharging unit when the sorter is mounted on the image forming apparatus.

FIG. 12 is a view for explaining sheet conveyance when a sorter is attached to the image forming apparatus.

FIG. 13 is a diagram illustrating a relationship between the transfer unit of the image forming apparatus and a duplex unit having the sheet transport positioning device according to the embodiment of the present invention when the transfer unit is lowered.

FIG. 14 is a diagram illustrating a relationship among a transfer unit, a toner collection unit, and a duplex unit of the apparatus.

FIG. 15 is a side view for explaining a relationship between a toner collecting unit and a duplex unit of the image forming apparatus.

FIG. 16 is a plan view illustrating removal of a toner collecting unit of the image forming apparatus from the apparatus main body.

FIG. 17 is a side view for explaining movement of the transfer unit with respect to the toner collecting unit of the image forming apparatus.

FIG. 18 is a circuit diagram for explaining processing of a recording signal on an image bearing member of the image forming apparatus.

19A and 19B show a groove of a paper guide body of the positioning device of the image forming apparatus according to the present invention, wherein FIG. 19A is a sectional view taken along line AA of FIG. .

FIG. 20 is a side view showing a state where the duplex unit is opened when a paper jam occurs.

FIG. 21 is a side view showing a state where an outer cover of the transport unit is opened when a paper jam occurs.

[Explanation of symbols]

2. Image carrier, 6 Transfer unit, 8 Duplex unit, 22 Corona charger, 54 Aligner roller, 82 Paper guide body, 83 Groove, 88 Pin.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B65H 5/38 B65H 9/16

Claims (3)

(57) [Claims] 1. A paper edge guide that guides one side edge of a sheet substantially parallel to a paper transport direction, and transports a sheet that is not in contact with the paper edge guide toward the sheet edge guide. And a sheet conveying means having a hardness higher than that of the sheet edge guide and projecting from the sheet guide portion of the sheet edge guide toward the sheet conveying means at a predetermined distance from each other, and substantially the same as the sheet to be conveyed. And at least two wear-resistant members that make line contact with the sheet transport positioning device. 2. The apparatus according to claim 1, wherein the wear-resistant member has an arc shape. 3. The paper transport positioning device according to claim 1, wherein the wear-resistant member is provided upstream and downstream in the paper transport direction from the transport means.