JPH0535015A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an image forming device whose size is not large and which is simple in constitution, and can cope with jamming of a sheet to a recording part and a both-side carrying path. CONSTITUTION:The device is provided with a corona charger 22 provided in the vicinity of an image carrier, a transfer unit 6 which supports the corona charger 22 and can move so that its one end is seperated from the image carrier to a process space 70; and a duplex unit 8 provided down ward the transfer unit 6 apart from the space 70 and can move in this space 70. A sheet carrying path and the both-side path are regulated at the upper side of the transfer unit 6 and with the process space 70, repectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention records on the first side of a sheet conveyed to a recording section through a sheet conveying path, reverses the sheet on the double-sided conveying path and sends it to the recording section. The present invention relates to an image forming apparatus capable of recording on one side, that is, on both sides of a sheet.

[0002]

2. Description of the Related Art In this type of image forming apparatus, conventionally, a paper jam is dealt with by independently considering the recording section and the double-sided conveyance path. That is, in the case of a large size, two holes are provided in the apparatus main body so as to correspond to the recording section and the double-sided conveyance path, respectively, and the paper jam is processed through these holes. Also, for small-sized ones, the clamshell method is used to eliminate the paper jam in the recording unit to eliminate the space for dealing with the paper jam inside the device. It is dealt with by a method different from.

[0003]

However, if a paper jam is dealt with at a different place between the recording section and the double-sided conveyance path as in the conventional case, the apparatus becomes larger in size. Further, if the clamshell method is adopted, the configuration for opening the recording unit becomes complicated.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image forming apparatus capable of coping with a paper jam between a recording section and a double-sided conveyance path with a simple structure without increasing the size of the apparatus itself.

[0005]

SUMMARY OF THE INVENTION An image forming apparatus according to the present invention has a double-sided path for reversing a sheet having one side printed in a recording section through a sheet conveying path and again conveying the sheet to the recording section. However, the paper guide forming a part of the double-sided path is located opposite to the unit forming a part of the paper carrying path with the space interposed, and the paper carrying path of the recording unit is opened by the movement of the unit. When not
The paper guide is configured to move over the movable range of the unit, and a part of the double-sided path can be opened.

[0006]

In the image forming apparatus of the present invention, when a paper jam occurs in the recording unit, the unit is moved into the space to release the paper conveyance path, and when a paper jam occurs in the double-sided conveyance path. In order to deal with paper jams at both locations, the paper guide is moved into the space to release the double-sided conveyance path.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, referring to FIG. 1, the overall construction of an ionographic image forming apparatus according to an embodiment of the present invention will be described.

Paper feed cassettes 9 for accommodating unused paper sheets and detachable from the main body of the apparatus are mounted in two upper and lower stages. A paper feed roller 13 for feeding the paper is provided above the tip of each cassette 9, and a pair of separation rollers 14 and 15 for separating the paper into one sheet are provided rotatably on the apparatus body side in front of the tip of the cassette. There is. An image carrier 2 made of a dielectric drum is rotatably provided in the main body of the apparatus. Then, the recording head 3 including 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 the toner on the image carrier 2 are conveyed. A corona charger 22 for transferring to an incoming sheet, 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. Between the image carrier 2 and the corona charger 22, that is, the registration roller 20 for transporting the paper to the recording unit is rotatable with respect to the main body of the apparatus, 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 sheet feeding 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 feeding cassette 9 and the registration roller 20 by the lower surface of the guide 17 and the upper surface of another guide 18. The lower surface of the guide 18 and another guide 19 lead to the third paper path 61 leading to the registration roller 20.
Are formed. The third paper path 61 is provided when an elevator mechanism (not shown) is attached to the apparatus body.
It serves as a conveyance path for the paper sent from this mechanism. Further, the roller 56 and the roller 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,
The fourth paper path 62 is formed. These first to fourth
The paper paths 59 to 62 are merged into one on the paper feed cassette side of the registration roller 20, and the first actuator 21 for detecting the presence or absence of paper is arranged at this portion. Further, a vacuum fan 63 (FIG. 14) is provided on the downstream side of the corona charger 22 in the sheet conveying direction. The transfer unit 6 is supported by 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 paper is sandwiched between the two and the paper can be conveyed toward the recording unit. A fixing unit 5 for fixing the toner image transferred on the paper to the paper is provided further downstream of the transfer unit 6. Furthermore, this fixing unit 5
A transport unit 10 having a function of allocating a paper path is provided on the downstream side of. As shown in detail in FIG. 2, the transport unit 10 is provided with first to fifth transport rollers 27 to 31 rotatably. The sheet transported from the fixing unit 5 is guided to the transport unit 10 through the fifth sheet path 49 formed between the lower surface of the guide 48 and the unit 101 section. 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 the paper to the sample tray 25 are arranged on the downstream side of the sheets 7 and 28, and one roller 31 is pressed by the other roller 30. . Further, a switching gate 33 is loosely fitted to the rotation shaft of the fourth roller 30 so as to be swingable about the rotation shaft 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 paper. In the state where the switching gate 33 is on the first lower side in FIG. 2, the fifth paper path 49 is located on the upper surface 33a side of the switching gate 33 and on the sixth downstream side of the first and second rollers 27 and 28. It communicates with the paper discharge unit 11 (FIG. 1) through the paper path 50. On the other hand, when the switching gate 33 is rotated to be in the second upper state shown in FIG. 3, the fifth paper path 49 has the lower surface 33b of the switching gate 33.
Side, and the fourth and fifth rollers 3 via the eighth paper path 52 downstream of the first and second rollers 27, 28.
It is connected to between 0 and 31. That is, this 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, the paper discharge unit 11 rotatably supports a pair of pinch rollers including a driving roller 35 and a driven roller 36 pressed by the driving roller 35. The driven roller 36 includes a substantially L-shaped third actuator 37 so that the driven roller 36 can swing about the rotation axis.
Is loosely fitted to the rotating shaft at the center. A photo interrupter 38 is provided near the actuator 37 to detect its operation. These rollers 3
Reference numerals 5 and 36 can be rotated forward and backward by a drive mechanism (not shown). At the time of forward rotation, the sheet has a function of discharging the sheet conveyed from the conveyance unit 10 to the tray 24 at the upper part of the apparatus, and at the time of reverse rotation, returns the sheet to the conveyance unit 10 again. It has a function.
That is, at the time of reverse rotation, since the switching gate 33 is in the first state shown in FIG. 2, the sixth paper path 50 is
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) through the seventh paper path 51.

As shown in FIG. 1, the duplex unit 8 is provided with an aligner roller 54 for feeding the 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-mentioned roller 5 provided substantially parallel to the registration roller 20 in order to send the sheet to the registration roller 20 again.
6 and a roller 57 pressed against it.
The duplex unit 8 is located directly below the transfer unit 6 and can be retrofitted by the user. A toner collecting unit 7 is provided between the transfer unit 6 and the duplex unit 8.
The unnecessary toner collected from the image carrier 2 by the cleaning unit 58 is sent to the toner collecting unit 7 and is accumulated there until it reaches a certain amount.

With the above configuration, the paper feed cassette 9
The paper fed out from the first or second paper path 5
It is sent to the nip portion between the registration roller 20 and the pinch roller 64 through 9 or 60, and is sent to the recording portion at a timing with the image, and the image is transferred by the corona charger 22. After that, the toner images are fixed by the fixing rollers 26a and 26b of the fixing unit 5, passed through the fifth paper path 49, nipped between the first roller 27 and the second roller 28, and held in the first state. The guide surface 33a, which is the upper surface of the switching gate 33, passes through the sixth paper path 50 and passes through the paper discharge unit 11
Is conveyed to the nip portion between the roller 35 and the roller 36 which are normally rotated. Then, it is nipped by these rollers 35 and 36, inverted, and discharged onto the tray 24 with the recording surface facing down. Thus, single-sided recording is completed.

On the other hand, in the case of double-sided recording, the trailing edge of the paper is the first
Also, the second actuator 32 detects that the nip portion of the second rollers 27 and 28 has passed, and the roller 35
Is reversed. As a result, the paper is returned and nipped between the second roller 28 and the third roller 29, and the seventh paper path 5
It is led to the duplex unit 8 through 1. In this unit 8, the side edge of the sheet is positioned by the aligner roller 54, inverted by the rollers 56 and 57, and guided again to the registration roller 20 through the fourth sheet path 62, like the recording on the first side. The second side is recorded in the process of. Then, as the switching gate 33 is rotated to the second state as shown in FIG. 3, the switching gate 33 passes through the eighth paper path 52 and is guided by the guide surface which is the lower surface 33b of the switching gate 33, and the fourth and the fourth sheets are guided. Fifth rollers 30, 3
1 is sent to the nip portion. As a result, these rollers 3
The sheets are nipped by 0, 31 and discharged onto the sample tray 25 with the recording surface facing up. For example, when the peripheral speed of the image carrier 2 is 1, the transport speed and the nip force of each roller are
The following relationships are set. Roller; Nip force (kgf); Speed ratio Peripheral speed of image carrier 2;-; 1 Conveyance of paper feed roller 13 and separation roller 14; 0.5; 3 Conveyance of registration roller 20 and pinch roller 64; 3; 1 Conveyance of fixing rollers 26a and 26b; 10; 1 Conveyance of first roller 27 and second roller 28; 0.5; 1.1 Conveyance of second roller 28 and third roller 29; 0.5; 1.7 Conveyance of the fourth roller 30 and the fifth roller 31; 0.5; 1.1 Conveyance of the roller 35 and the roller 36 in forward and reverse rotations; 0.5; 1.7 Aligner roller 54 and pinch roller 55 Transport of 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 about 3 times in order to increase the number of sheets to be printed within a fixed time. In addition, the pair of fixing rollers 26a and 26b and the registration roller 20
The conveyance speed of is almost the same as the peripheral speed of the image carrier,
This is to stabilize the conveyance of the paper 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 1.1 times is that the curl is reduced by applying tension to the paper coming out from the fixing rollers 26a and 26b. Further, the reason why the conveyance speed of the roller for double-sided recording thereafter is increased is to return the sheet to the registration roller 20 again in a short time so as to increase the number of sheets to be printed in a certain time during double-sided recording as much as possible. Thus, at the same time as increasing the roller conveyance speed, the conveyance path for double-sided recording should be as short as possible.
A compact device and paper conveyance without time waste are possible.

Next, the detailed structure of the transport unit 10 will be described. As shown in FIG. 5, the second roller 28 includes a horizontally extending stainless steel shaft 28e and two stainless steel shafts 28e that are rotatably fitted to the shaft 28e and are arranged at a predetermined distance from each other. And a plastic roller portion 28d. Rubber roller portions 28c fixed to a shaft 28e are provided on both outer sides of the roller portions 28d, respectively. The outer diameters of the roller portions 28d and 28c are set to be substantially the same. Both ends of the shaft 28e are rotatably supported by both frames protruding from the outer cover 10a of the unit via bearings, and the reduction gear 45 is fixed at the end on the drive side outside the frame. . This second roller 2
8, the first roller 27 is pressed by the spring 47 via the 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 with a predetermined distance from each other and having the same diameter and length, and three rubber roller portions 27b having a smaller diameter and a shorter diameter. Have. These small rubber roller portions 27b are fixed to the shaft 27c so as to be located on both outer sides and between both sides of the large rubber roller portion 27a. A drive gear 44a is fixed to the end of the drive-side shaft 27c, and the drive gear 44a meshes with the small-diameter gear portion of the reduction gear 45. As a result, the large rubber roller portion 27a and the roller portion 28d are brought into pressure contact with each other by the force of the spring 47, and the small rubber roller portion 27b and the roller portion 28c on both sides are pressed.
There is a gap between them. The distance between the centers of 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 received by the gears, and the large rubber roller portion 27a and the roller portion 28d are all used.
It becomes the nip pressure with. On the other hand, the third roller 29 is also pressed toward the second roller 28 by the 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 which are coaxially fixed to the shaft 29c of the third roller 29, and one roller portion 29 is formed by a spring 47.
a is pressed against the rubber roller portion 28c. When the reduction gear 45 is rotated by this mechanism, the second roller 28 is rotated, 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 rotational speed slower than that of the second roller 28 due to the reduction ratio of 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 slow rotation speed. Therefore, the small rubber roller portion 27a and the roller portion 28d
If the conveyance speed of the sheet nipped to and is 1, the speed of the sheet nipped and conveyed by the rubber roller portion 28c and the roller portion 29a is increased as described above, for example, 1.7. can do. The fourth roller 30
Both ends of the shaft 30e are rotatably fixed to the frame of the outer cover 10a of the unit by bearings. The shaft 30e has a gear 44b on the outside of the frame on the drive side.
However, a rubber roller portion 30d having the same diameter is provided near the center.
Each is fixed. Both ends of the shaft 31b of the fifth roller 31 are pressed in the direction of the fourth roller 30 by springs 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.
It is pressed against 0d. The non-nipped portion of the plastic roller portion 31a, that is, the outer end portion, has a large diameter, and serves to make the paper stiff. And FIG.
As shown in FIG. 3, the small-diameter gear portion of the reduction gear 45 fixed to the third roller 28 receives a driving force from the small gear portion via a gear train composed of two idler gears 46.
A gear 44b fixed to the fourth roller 30 is gear-connected. Thus, the drive system of the transport roller provided with the speed reduction mechanism is configured. Next, the second actuator 32 that detects the sheet will be described with reference to FIGS.

This actuator is made of synthetic resin by integral molding, and the shaft 28e of the second roller 28 is formed.
Two small-diameter portions 28 formed at a predetermined distance from each other
The bearing portions, the outer periphery of which is partially cut off, are spread and fitted into a and 28b (FIG. 5), so that they are swingably supported around the rollers 28. A metal weight 32d is inserted and fixed to the lower portion of the actuator 32. Also, the arm portion 3 extending upward and downward so that the actuator 32 actually contacts the paper.
2a and 32b are a first roller 27 and a second roller 28.
Nip tangent to the second roller 28 and the third roller 2
9 protrudes longer than the nip tangent line to 9 and its tip is located downstream of the nip point in the sheet conveyance direction. Therefore, only the leading edge of the sheet, which is securely nipped between the rollers, pushes the actuator 32 so that the weight 32d
The second roller 28 is rotated about its weight. The actuator 32 is provided with a light shielding portion 32c that has a function of shielding light.
2c indicates when the sheet is not detected, that is, when the sheet is between the first and second rollers 27 and 28 or the second and third rollers 2 and 2.
When it is not between 8 and 29, as shown in FIG. 6, the photo interrupter 38 is in contact with the photo interrupter 38 with the moment of the weight 32d to block the optical axis of the photo interrupter 38. Then, the leading end of the sheet nipped by the roller is the arm portion 32a or 3
When 2b is pressed, the light shielding portion 32c is rotated counterclockwise in FIG. 6 and is separated from the optical axis portion, and the photo interrupter 38 is moved.
Can be released and the paper can be detected. With this configuration, one actuator 32 and the photo interrupter 38 can detect paper in different paper paths conveyed in different directions in a compact space without providing a new holding member for the actuator 32. There is. Next, the switching gate 33 will be described.

The switching gate 33 is formed by molding integrally with the mold and, as shown in FIG. 7, the fourth roller 30.
Has a bearing part with a part of the outer periphery cut out at positions corresponding to the small diameter parts 30a, 30b, 30c, respectively. By pushing the bearing part and fitting it into the shaft 30e, the shaft of the roller 30 It is fitted so as to be swingable around 30e. Then, the boss 33 portion c provided at the driving side end portion of the switching gate 33 projects outward from the frame of the outer cover and fits into the hole 41a (FIG. 8) formed in the upper portion of the stainless steel link 41. ing. This link 41 engages with the plunger of the solenoid 40 at the U groove 41b formed at the lower end, and is attached to the plunger by a tension spring 42 hung between the hole 41c formed at the upper end and the frame. It is biased in the direction opposite to the bias direction. This hole 41
The a, the U groove 41b, and the hole 41c are formed so as to be aligned in a substantially straight line. Thus, when the solenoid 40 is turned on, the switching gate 33 is connected via the link 41.
Rotates downward about the axis of the fourth roller 30 to the first state shown in FIG. 8 (state shown in FIG. 2). On the other hand, when the solenoid 40 is turned off, the link 41 is moved upward by the urging force of the spring 42, and the switching gate 33 is rotated to the second state (the state shown in FIG. 3). This link 41
The rotation range of 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 has the fourth gate.
By rotating the tip about the axis of the roller 30 in the vicinity of the first and second to third rollers 27 to 29,
Switching gate 3 without providing a new center of rotation
3, the function of guiding the paper in the direction of the paper discharge unit 11, the function of guiding the paper in the direction of the duplex unit 8 from the paper discharge unit 11, and the function of guiding the paper in the direction of the sample tray 25 from the paper discharge unit 11 With the function to
A compact device can be provided by providing the functions of three paper guides. Next, the guide film 34 will be described with reference to FIGS. 2 and 3.

A guide 48 is mounted on the paper discharge unit 10 so as to be capable of thermal expansion in a direction perpendicular to the paper conveyance direction. The guide 48 having such a thermal characteristic is used in order to prevent the guide from being thermally expanded in the sheet conveyance direction by the heat of the sheet heated by the fixing roller 26 and hindering the conveyance of the sheet. Is. This guide 48 has a lower surface 4
8a is a paper guide surface, and one end of the guide film 34 is fixed to the upper surface with an adhesive. The guide film 34 is required to have heat resistance (melting point of 70 ° C. or higher) because it is provided near the fixing roller 26, and is also required to have abrasion resistance because it is worn by friction with the paper. Therefore, in this embodiment, a polyimide sheet having a thickness of 200 μ and a width of 10 mm is used. This guide film 34 is used for the first and second rollers 27, 2
It passes through the non-nip portion between 8 and contacts the switching gate 33 by its elastic force, extends in the direction of the sixth paper path 50, and the end portion projects from the hole 102 provided in the unit to the outside of the paper path. The protruding end is not fixed, and the width is set to be larger than the width of the hole 102.
It is designed so that the end does not go into 0. In order to make the device compact, the first to third rollers 27-
The diameter of 29 is designed small (about 12 mm in diameter in this embodiment). When a roller with a small diameter is used as described above, if there is curl at the trailing edge of the paper, the paper ejected from the fifth paper path 49 to the sixth paper path 50 is reversed by the roller 35 (FIG. 4) of the paper discharge unit 11. This makes it difficult to accurately enter the nip portion of the second and third rollers 28, 29.
Therefore, the guide film 34 serves 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 by its elastic force. This guide film 34 is more effective as it projects nearer the tip of the second roller 28 and the switching gate 33. At that time, in order not to prevent the leading edge of the paper coming from the fifth paper path 49 from being obstructed, the first paper path 49 side is moved to the first position.
Is provided between the roller 27 and the second roller 28. Further, since the distance between the two rollers 27 and 28 is small, 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 projects from the sixth paper path 50 to the outside of the path is to prevent the thin guide film 34 from being damaged by the processing when a paper jam should occur. Furthermore, the guide film 34
Since the sheet is made of a thin sheet material, even when the switching gate 33 is rotated, the upper surface 33a pushes the guide film 34 as shown in FIG. 3 to form the eighth sheet path 52, and the sheet is discharged to the sample tray 25. Is possible.

It is important for the roller 35 provided in the paper discharge unit 11 to switch between normal rotation and reverse rotation. The first-side recorded sheet that has been conveyed from the fifth sheet path 49 is the first and second rollers 27, 28.
It is necessary to reversely rotate the roller 35 after the trailing edge of the sheet is reliably passed through this nip portion by being conveyed by the above.
If this reverse rotation is too early, paper jam will occur, and if it is too late, useless time will be required for movement of the paper. In the present embodiment, the rear end of the sheet passes through one arm portion 32a of the second actuator 32 configured as described above, and the light shielding portion 3 is formed.
The timing when 2c interrupts the optical axis of the photo interrupter 38 (FIG. 6) or the sequence in which the roller 35 is rotated in the reverse direction after a certain time T1 described later ensures the nip between the first and second rollers 27 and 28. The sheet 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 transport state, and the actuator 3 is again driven.
Since the optical axis of the photo interrupter 38 is blocked for a certain period of time by pressing the other arm 32b of No. 2 by the light shield 32c, it is possible to know that the paper has been reliably conveyed to the seventh paper path 51 by detecting this. You can Therefore, even if the paper is not conveyed to the seventh paper path due to some kind of paper jam, this can be detected promptly and the 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 discharge unit 11
Is pressed against the drive roller 35 by a spring (not shown) in the direction of the center of the drive roller 35, and is driven by the rotation of the roller 35. And this roller 36
A small-diameter portion is formed substantially at the center of the stainless rotary shaft, and an L-shaped third actuator 37 is fitted into the bearing by cutting off a part of the outer periphery of the actuator to spread it loosely and loosely. It is fitted. One arm portion 37d of the actuator 37 has an arc shape, and a tip portion 37a thereof projects toward the tray 24. The tray 24 is inclined so that the side of the paper discharge unit 11 becomes lower as shown in the figure. The lower surface of the arm portion 37d is in direct contact with 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 provided near the tip of the actuator 37.
7b is inserted, 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 photo interrupter 38. At this time, the optical axis of the photo interrupter 38 is blocked by the light blocking portion 37c, and it is detected that there is no sheet. The sheet is conveyed from the conveying unit 10 through the sixth sheet path 50 and is conveyed by the nip portions of the first and second rollers 35 and 36,
One arm portion 37d of the actuator 37 at the leading edge of the sheet
When contacting the lower surface of the
The inside is rotated counterclockwise, and the light shielding portion 37c is separated from the optical axis of the photo interrupter 38, and it is detected that the paper comes. After that, when the trailing edge of the paper leaves the rollers 35 and 36 and the paper falls into the tray 24, the actuator 37 returns to the state shown in FIG. 4 by its own weight (by the action of the weight 37b), and the photo interrupter 38 moves. The optical axis is blocked. When 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 front end portion 37a of the actuator 37 rides on the stacked paper upper surface 23, the actuator 37 is rotated counterclockwise, and the optical axis of the photo interrupter 38 is blocked. Disappear. In this way, when the optical axis of the actuator 37 is not interrupted for a certain period of time during the paper discharge operation for a time period during which a plurality of paper sheets are discharged, it is determined that the stacked paper on the tray 24 is full and a new paper feed operation is performed. In addition to prohibition, full paper information is sent to a panel (not shown) so that the operator can know this state. This paper feed operation prohibition is for tray 2
The recorded sheet 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 shield section 37c of the actuator 37, and the information on the panel is also erased. The third actuator 37 is
Only full sheets of paper stacked on the tray 24 are detected, and when a sorter described later is not installed, paper jam of paper traveling is not detected. This is to prevent the actuator 37 from outputting erroneous information about a paper jam when the actuator 37 is erroneously touched from outside the device. As in this embodiment, the third
The actuator 37 is attached to the shaft of the driven roller 35, so that a new holding member is not required and a full-paper detection mechanism can be configured compactly. Further, the actuator can be passed from the upstream side to the downstream side of the nip portion between the rollers 35 and 36, and the one arm portion 37d has an arc shape and the tray 24 has an inclination so that it can be conveyed. The contact angle with the incoming paper can be kept small at all times, and the shape can be made so as not to damage the leading edge of the paper, and the tray 24 of the actuator 37 is provided.
It is possible to shorten the protruding length upward. As a result, the actuator 37 does not get in the way when the operator removes the sheets stacked on the tray 24.

FIG. 9 shows the second actuator 3 described above.
The operation timings of the second actuator 37 and the third actuator 37 are shown. When the second actuator 32 repeatedly outputs ON and OFF at a predetermined operation time T1, it is detected that there is no paper jam in the conveyance path to the actuator 32. Then, when the next detection signal is not detected even after the predetermined time T1, the paper jam is determined to have occurred. The third actuator 37 detects the front edge of the sheet after a predetermined time T2 has elapsed since the second actuator 32 detected the front edge of the sheet (that is, T2 is the second edge).
Corresponding to the sheet moving time from the actuator 32 of the third actuator 37 to the third actuator 37), the second actuator 3
When 2 does not detect the paper, it detects the trailing edge of the paper. This third actuator 37 is operated for a predetermined time (T3 +
If the detection signal continues to be output even after T4) has elapsed, it is determined that the tray 24 is full.

As an option, a sorter 16 or the like may be attached to the apparatus as shown in FIG. With the exception of the switching gate 33 described below, the sorter 16 conveys the fed paper upward by an endless belt, and sequentially sorts the paper into a plurality of trays arranged vertically and discharges the paper. Since it is a well-known configuration that has been configured,
The description is omitted. The switching gate 39 selectively switches 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, 36. The switching gate 39 is rotatably provided on the sorter main body around the shaft 39a, and the tip portion 39b of the switching gate 39 is located at the roller 3 by a drive mechanism (not shown).
The position below the tangent line of Nos. 5 and 36 (the position shown in FIG. 10) and the position above the nip tangent line are selectively switched. The center portion of the switching gate 39 facing the third actuator 37 is cut as shown in FIG. 11, and one arm portion 37a of the actuator 37 can be inserted into this. Therefore, the actuator 37 and the switching gate 39 are wrapped in a comb shape so as not to interfere with each other in the operation range. Even if the sheets are stacked on the tray 24 in the full state, the switching gate 39 and 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 sending to the sorter 16, as shown in FIG. 10, the actuator 37 is rotated counterclockwise while the sheet is passing, the tip portion 37a is lifted and the interruption of the optical axis of the photo interrupter 38 is released. To be done. When the paper passes through the actuator 37, the actuator 37 returns to the original position as described above, and the photo interrupter 38 is blocked from the optical axis. At this time, that is, when the sorter 16 is used, the photo interrupter 38 does not use the actuator 37 as a full-paper detection, but as a passage detection of the leading edge or the trailing edge of the sheet. Therefore, it is not necessary to newly provide the paper detection sensor in the sorter 16. Further, when the paper is discharged onto the tray 24, or when a part of the paper is once put out on the tray 24 in the double-sided recording mode and the roller 35 is reversed again to feed the paper into the apparatus, the switching gate is used. The knob 39 is rotated slightly clockwise in FIG. 10 to move its tip 39b to a position on the arm portion 37d of the actuator 37. With such a configuration, it is possible to cope with the case where the total length of the sheet to be double-sided printed is long and the long portion is put out 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 full sheet detection as in the case where the sorter 16 is not provided. That is, when the sorter 16 is mounted, and when the optical axis of the photo interrupter 38 is not blocked by the time-depleted timing when the paper is discharged to the tray 24, a new recording for sending to the sorter 16 is performed. The paper is immediately prohibited, and the prohibition is released when the paper on the tray 24 is removed and the optical axis of the photo interrupter 38 is blocked. As a result, when the paper is fed to the sorter 16, the actuator 37 is used to detect the leading edge and the trailing edge of the paper, and when the paper is discharged to the tray 24, it is used to detect the full paper. It is possible to simplify communication with the apparatus main body of the sorter 16 without newly providing a paper detection mechanism on the sorter 16 side. Further, the optional sorter 16 and the standard equipment tray 24 are arranged above and below, and the sorter 16 can be mounted while making full use of the tray 24 full paper detection mechanism and the paper storage function.

In this embodiment, the sorter 16 can be mounted while maintaining the function of the standard tray 24, and the switching gate 39 is provided on the sorter 16 side. Therefore, for example, without the switching gate 39, even if the standard tray 24 becomes unusable, the actuator 3
7 is used as a sheet detection when the sorter 16 is attached, and when the sorter 16 is not attached, switching the usage method to detect a full sheet on the tray 24 does not require a new sheet detection mechanism on the sorter side. Has an effect on. Full paper detection when the sorter 16 is not installed,
The sheet detection operation when the sorter 16 is attached will be described with reference to FIG.

When the power P is turned on, it is determined whether the detection signal from the third actuator 37 is Off (S).
1). In the case of No, the paper feeding operation is prohibited (S2) and the paper full is displayed. On the other hand, if Yes,
It is determined whether the counter C is set to the initial state (K = 0) and the paper 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 feeding is started and a detection signal is output from the second actuator 32 (S5), the counter B is in the initial state (J = 0).
Then, the counter C is turned on, and this constant (J = J +
When 1) is counted (S6), it is judged whether 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, when the result of step 7 is No, the counter C starts counting (K = K + 1) (S10), compares the count number K with the set value M (S11), and while K does not exceed M, the counter is counted. When B is turned off and K becomes larger than M, the paper on the tray 24 is full, so the paper feeding operation is prohibited (S2).

The paper is discharged to the tray 24 as described above. On the other hand, when discharge to the sorter 16 is set (Yes in step 3), the switching gate 3
9 is turned on and rotated to the lower position as shown in FIG. After this, the count J of the counter C is T3 + T4
If it becomes 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 rear side of the plastic body that is integrally molded,
Two boss portions 601 (only one can be seen in the figure) that are horizontally separated from each other are rotatably fitted and held in the frame 68 of the apparatus main body in the vertical direction. The front side of this plastic body is hooked on the unit 1 with a hook (not shown), and as shown by the solid line,
It is held substantially horizontally (horizontal position). By removing this 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 (inclined position), which is indicated by the two-dot broken line, around the rear boss portion 601. Is possible. In the transfer unit 6, as shown in FIG. 14, a guide portion 602 formed on one side so as to form a paper path for guiding the paper to the registration roller 20.
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
A guide portion 6 formed below the paper path between the four
And 03 parts are provided. Further, a fan 63 for sucking the sheet after the transfer 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 in the horizontal position, the pinch roller 64 presses the registration roller 20 horizontally, and the registration roller 20 is pressed.
It follows the function of conveying paper. The corona charger 22 is located below the image carrier 2 in the vicinity thereof, and has a guide portion 6
Reference numeral 03 serves to guide the paper and guide it 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 moves about 1
It rotates 6.5 degrees and abuts and is fixed to a frame portion (not shown). In this state, the front side is opened along the paper path, that is, the lower surface of the transfer unit 6 in the horizontal position and the deyucreps unit 8 in the horizontal position described later.
The processing space (processing space) 7 that is regulated between the upper surface of the
It is possible to remove jammed paper on the transfer unit 6 and to replace the corona charger, which is a regular replacement part, through the holes 0 and the holes 69 formed in the front part of the frame 68. Next, the toner recovery unit 7 will be described.

As shown in FIG. 14, the toner recovery unit 7 is mounted in the processing space 70 which is regulated between the transfer unit 6 and the deucrepse unit 8. As shown in FIGS. 15 and 16, the toner recovery unit 7 includes a bottle holder 71 made of sheet metal and a bottle 72 made of plastic which is a storage member for actually storing toner.
It is composed of Since the bottle 72 is regularly replaced or the toner inside is discarded, the bottle 72 is mounted between the mounting portions 71c and 71d projecting upward so as to face the bottle holder 71 at a predetermined interval. It is fitted by utilizing the elastic force of, and both are detachably integrated. The bottle holder 71 includes a bent portion 71 formed on a stay portion passed from the front side to the rear side of the frame 68.
It is held slidably along b. When the toner collecting unit 7 is mounted in the operating position,
The mounting portion 71a is fitted and positioned with respect to the frame 68 (FIG. 15), and the bottle 72 is arranged at the rear portion (second position) of the processing space 70. The residual toner collected by the cleaning unit 58 (FIG. 1) passes through a not-shown gukto (toner conveying means) on the rear side and is accumulated in the bottle from the opening 72b of the bottle 72. The bottle holder 71 can be pulled out to the front side as shown in FIG. 16 to a position where the protruding portion 71e comes into contact with the frame 68,
At this position (first position), the bottle 72 is in the bottle holder 7
It is attached to and detached from 1. That is, the residual toner can be stored in the bottle 72 with the toner collecting unit 7 inserted in the rear side, and the bottle 72 can be replaced with the bottle 72 pulled out to the front side. It should be noted that the bottle 72, at the mounting position, as shown in FIG. 17, when the transfer unit 6 is rotated to the inclined position, the bottle 72 does not interfere with this rotation so that the bottle 72 is located at the rotation center side (back side). Located on the upper surface of the front portion 72a
Is inclined. Next, the duplex unit 8 will be described.

As shown in FIG. 14, the duplex unit 8 is provided directly below the transfer unit 6 and the toner recovery unit 7 and is provided on the bottom surface of the apparatus with a processing space 70 therebetween. As shown in FIG. 15, the duplex unit 8 includes a roller 56 that is intermittently driven from the main body of the apparatus via a clutch 85.
And a roller 57 that is pressed against and is driven in parallel with this. These roller pairs 56 and 57 are arranged parallel to the registration roller 20. The driven roller 57 is supported by a rotary shaft 81 extending in parallel with the rotary shaft of the transfer unit 6 at a rear portion thereof, and is held by a paper guide body 82 rotatably provided around the rotary shaft 81. Paper guide body 82
The nip with the roller 56 is released by lifting. A part of the front side of the paper guide body 82 spreads out in a substantially horizontal plane toward the aligner roller 54,
The lower surface and the upper surface of the paper guide 84 facing each other serve to guide the leading edge of the paper to the nip portion of the rollers 56 and 57. Further, the paper guide body 82 extends toward the upstream side so as to be curved upward, and the roller 56 is provided at this extending portion.
Receives the rotational force of via the pulley 86 and the belt 87,
An aligner roller 54, which is located near the rear edge of the sheet and is inclined (5 to 20 degrees) in the direction in which the sheet is conveyed rearward with respect to the sheet conveying direction, and a pinch that is pressed in parallel with and is driven by the aligner roller 54. The roller 55 and the roller 55 are rotatably mounted (FIG. 14). Therefore, the aligner roller 54 is driven to rotate when the roller 56 is driven.
The paper guide body 82 is formed by integral molding of synthetic resin,
A groove 83 for positioning the rear edge of the paper is integrally molded along the transport direction. That is, this groove 83
Has a ridge edge 82b protruding upward from the guide rib surface 84a of the paper guide 84 on one side. The depth direction is rearward and the longitudinal direction is along the transport path on the front surface of the ridge edge 84b. Is formed in this way. The groove 83 has a width (vertical direction) of 1 to 2 mm and a depth of 10 mm, and the groove bottom is 2 mm in parallel with the rear side edge of the sheet at the time of transfer of the first side when viewed in the sheet conveying direction. It is located on the rear side. 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, the transport path defined by the groove 83 is backward by 2 mm (in FIG. 1). (It is shifted in the direction of the paper surface when viewed, and in the right direction when viewed in FIG. 15). Similar to the guide rib surface 84a of the paper guide 84, the groove 83 also extends upward along the same in the direction of the aligner roller 54, and guides one side edge of the paper in accordance with this shape.

The one-side recorded sheet that has been driven to reverse by the sheet discharge unit 11 and has been conveyed to the duplex unit 8 through the transport unit 10 and the seventh sheet path 51 is
One side is guided by the groove 83, the lower surface is supported by the guide rib surface 84 over the entire width, and the aligner roller 54 conveys the nip portion between the rollers 56 and 57. At this time, the conveying force of the aligner roller 54 is the second and third rollers 28,
Since the conveying force is smaller than the conveying force of 29 and the conveying speed is set to be high, the sheet slips on the sheet while the trailing edge of the sheet is nipped by the rollers 28 and 29, and the trailing edge of the sheet moves to the rollers 28 and 29. After passing the nip of 29, the sheet is conveyed toward the rollers 56 and 57 while being shifted toward the bottom of the groove 83, which is the conveying direction of the aligner roller 54, at the conveying speed of the aligner 54. As a result, the paper is
The rear end portion is positioned at the bottom of the groove 83, and the roller 5
6 and 57, and is guided by the guide 19 and the guide portion 602 of the transfer unit 6, and again the registration roller 20
Be carried to. At this time, since the transport speed of the aligner roller 54 is higher than the transport speed of the roller 56, after the leading edge of the sheet is nipped by the rollers 56 and 57, the aligner roller 54 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 that the paper guide 84 is curved,
Even thin thin paper can be transported without buckling. When the leading edge of the sheet reaches the registration roller 20, the rotation of the registration roller 20 is stopped, the first actuator 21 detects the leading edge of the sheet, and the leading edge of the sheet is applied to the nip point between the pinch roller 64 and the registration roller 20. After forming the loop, the driving of the roller 56 is stopped by the clutch 85. In this state, since the guide 19 is curved, the sheet reversely buckles and there is no space to form a loop, so the loop formed here is minute. Next, the registration roller 20 is driven again in synchronism with the image on the image carrier 2, and the sheet is conveyed so as 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 conveyance speed of the roller 56 is faster than that of the registration roller 20, the sheet buckles due to the curved fourth paper path 62 and the effect that the conveyance force of the roller 56 is small and the sheet slips. Without registration roller 20
It is transported at the speed of. By adopting such a sequence, it is possible to reliably carry out registration between the paper and the image even in the paper path where only minute loops can be formed. Further, the load on the roller 56 located at a position different from the registration roller 20 in the conveying direction is reduced to reduce the load.
It is possible to ensure reliable transportation in. In the transfer of the second surface, the paper is positioned by the position of the groove 83 and is shifted to the rear side by 2 mm as compared with the case of the first surface. In accordance with this, the image on the image carrier 2 by the recording head 3 is also 2 mm.
The recording is performed by shifting in the lateral direction (direction orthogonal to the transport direction).

In this embodiment, the groove 83 is formed by integral molding.
By forming the paper guide 84 having the shape, an inexpensive and complicated shape is possible. However, with a 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. In order 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 at right angles to the extending direction of the groove,
The pin is inserted and fixed in the paper guide 84 such that the outer peripheral surface of the pin is flush with the downstream side portion 83a of the bottom surface of the groove 83.
One of these pins 88 is arranged on each of 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 upstream groove bottom portion 83b is deeper than the downstream groove bottom portion 83a with the downstream pin 88 as a boundary, and the bottom portion 83b does not contact the paper. Is done. Align paper with roller 5
When the sheet is conveyed only by 4, the two pins 88 receive a rotational moment generated on the sheet due to the conveying force of the aligner roller 54 and the resistance of the sheet path. When the trailing edge of the sheet comes off the upstream pin 88, the leading edge of the sheet has already been positioned and conveyed by the roller 56. However, when only the trailing edge of the paper rotates and comes into contact with the groove bottom portion 83b, the bottom portion is abraded, and the trailing edge of the paper is pinched by the groove portion caused by the abrasion to cause a paper jam.
Is at a position that is released by a predetermined distance (l) so as not to contact the paper. In this embodiment, l = 0.5 mm.
The rotation of the paper depends on the number of aligner rollers 54, the nip width,
Although it depends on the shape, if at least a metal pin is provided on the upstream side of the center of gravity of the paper when the paper starts moving in the direction of the groove 83 in the paper transport direction, it is not limited to this embodiment and it is possible to prevent wear of the groove bottom. effective. When the aligner roller 54 is set upstream of the center of gravity of the sheet as in the present embodiment, it is more effective to provide the pin 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 side edge is guided by the groove 83. Therefore, in order to guide the front side, Part guide body 82
The conveyance path can be constructed by simply extending the sheet. Therefore, even if a paper jam occurs, by opening the paper guide body 82 upward around the opening / closing center 81, it becomes possible to easily perform processing. The drive circuit of the recording head (ion cartridge) 3 will be described below with reference to FIG.

An output side of a raster image processor (RIP) 100 that transmits a video signal in byte units is connected to a buffer section 102 via an interface (I / F section) 101. In addition, this I / F unit 101
Is connected to one output side of the CPU 103, and the CPU 103 is connected to the side registration setting unit 104. A single-sided recording switch 105 and a double-sided 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 the user. When the one-sided recording switch 105 is selected, and when the both-sided recording switch 106 is selected and one side is recorded, the CPU 103 drives the buffer unit 102 with a predetermined command and outputs a normal recording signal. Then, the double-sided recording switch 106 is set to drive the buffer unit 102 via the side-registration setting unit 104 so as to output a shift recording signal to be described later when recording on the other surface. The side registration setting unit 104
The output side of is connected to the input side of the buffer unit 102. The output side of the buffer unit 102 converts the recording signal sent from the buffer unit 102 into a matrix-shaped 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 section 107 is connected to an ion cartridge (ICG) driver 108, and the ion cartridge (ICG) 3 is driven by a high voltage signal for driving based on a recording signal from the deskew section 107.

The image carrier 2 is provided with an encoder 110 for detecting the number of rotations of the image carrier 2.
The detection signal from the
The recording signals are input to the I / F unit 101, the buffer unit 102, and the deskew unit 107, respectively, and each recording signal is output at a predetermined timing. That is, double-sided recording switch 1
When 06 is selected, the timing for recording on the other surface is set.

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

The frame 68 is entirely made of plastic 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 located substantially opposite to each other, and the toner recovery unit 7 is located behind the processing space 70 between them. Since the toner collecting unit 7 is arranged on the rear side, even if the front side of the transfer unit 6 is lowered, it does not interfere with the toner collecting unit 7. Further, as shown in FIG. 17, the transfer unit 6 has a planar surface only on the front side, so that it does not interfere with the toner recovery unit 7. Since the transfer unit 6 and the duplex unit 8 are opposed to each other with the processing space 70 in between, it is possible to alternately open and close 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 rotational ranges of the transfer unit 6 and the duplex unit 8 in this space 70 overlap, the space can be made smaller than the case where independent moving spaces for both are formed. . It is also used as a space for lowering the transfer unit 6 when the corona charger, which is a consumable item, is replaced. Further, when replacing the bottle 72, it is used as a space for pulling out the toner recovery unit. Since these usage states do not occur at the same time, one space can be used for multiple purposes, and the device can be made compact. Further, 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 inner side of the apparatus (see FIG. 2).
0), that is, the total length of the paper guide body 82 is set shorter than the total length of the transfer unit 6, so that the transfer unit 6 can be opened at a larger angle. Further, the paper guide body 82 can also be opened at a larger angle.
Of course, the total length of the transfer unit 6 may be set longer than the total length of the paper guide body 82.

Next, the paper jam removal of the transport unit 10 will be described. As shown in FIG. 21, the transport unit 10 is integrated with the outer cover 10a and is openably and closably held with respect to the apparatus main body about a rotation center 65 as a fulcrum.
It is possible to rotate 45 degrees. As a result, in the opened state, all of the fifth paper path 49, the sixth paper path 50 and the seventh paper path 51 can be opened at the same time. In the present embodiment, the paper path for discharging 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. It is much shorter than that, so there is no distinction between single-sided recording part and double-sided recording part.
The paper jam can be dealt with only by opening the transport unit 10. In addition, when the paper is discharged 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, opening the transport unit 10 ensures that a part of the paper will appear. As a result, even when the paper is discharged to either the tray 24 or the sample tray 25, the processing can be performed by opening the transport unit 10.

[0036]

In the image forming apparatus of the present invention, when a paper jam occurs in the recording unit, the unit is moved into the space to release the paper conveyance path, and the paper jam occurs in the double-sided conveyance path. In such a case, the paper guide is moved into the space to release the double-sided conveyance path, and the paper jam at both places is dealt with. Therefore, the space for releasing the paper conveyance path and the double-sided conveyance path are released. Can be shared with space. For this reason, the total space for releasing both paths is small, and it is possible to downsize the entire apparatus and simplify the configuration.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an entire image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a transfer unit of the same apparatus with a switching gate of the transfer unit in a lower position.

FIG. 3 is a diagram showing a transfer unit of the same apparatus with a switching gate of the transfer unit in an upper position.

FIG. 4 is a diagram showing a paper discharge unit of the apparatus.

5 is a diagram illustrating a transport roller deceleration mechanism of the transport unit shown in FIG.

FIG. 6 is a diagram illustrating a drive system of a transport roller of the transport unit shown in FIG.

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

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

FIG. 9 is an explanatory diagram of output signals of the sensor by the second and third actuators used in the present device.

FIG. 10 is a view showing the sorter and the paper discharge unit when the sorter is attached to the apparatus.

FIG. 11 is an exploded perspective view for explaining the positional relationship between the switching gate of the sorter and the actuator of the paper discharge unit when the sorter is attached to the apparatus.

FIG. 12 is a diagram for explaining conveyance of a sheet when a sorter is attached to the apparatus.

FIG. 13 is a diagram illustrating a relationship with the duplex unit when the transfer unit of the apparatus is lowered.

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

FIG. 15 is a side view for explaining the relationship between the toner recovery unit and the duplex unit of the same device.

FIG. 16 is a plan view for explaining how the toner recovery unit of the apparatus is taken out from the apparatus body.

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

FIG. 18 is a circuit diagram for explaining processing of a recording signal to the image carrier of the apparatus.

FIG. 19 is a sectional view taken along the line AA of (B) showing the groove of the paper guide body of the duplex unit of the apparatus.
And (B) is a top view.

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

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

[Explanation of symbols]

2 ... Image bearing member, 6 ... Transfer unit, 8 ... Duplex unit, 22 ... Corona charger, 49 ... Fifth paper path, 59 ... First paper path, 60 ... Second paper path, 61 ... Third
Paper path, 70 ... Processing space,

Claims (5)

[Claims] 1. A paper guide which forms a part of the double-sided path having a double-sided path for reversing the paper having one side printed in the recording section through the paper-conveying path and again conveying the paper to the recording section. The paper guide is located at a position facing a unit forming a part of the paper transport path across the space and the paper transport path of the recording unit is not opened by the movement of the unit. An image forming apparatus, wherein the image forming apparatus is configured to move over a possible range and to open a part of the double-sided path. 2. The unit and the paper guide each have a center of rotation on the back side of the apparatus main body, extend toward the front side of the apparatus main body, and have different lengths up to the extended end portion. The image forming apparatus according to claim 1, wherein the image forming apparatus comprises: 3. A recording section for recording an image on a sheet, a first transport path passing through the recording section, and a sheet having the first side recorded by the recording section is reversed and recorded on the second side of the sheet. As described above, there is a second transport path for transporting the sheet to the recording section, which constitutes one side of the first transport path facing the recording section, and which includes the transfer section which constitutes the recording section and which transfers the image to the sheet. A sheet guide for one side of the second conveyance path, the unit and the sheet guide are opposed to each other with a space in the apparatus main body, and the first and second sheet paths are connected to each other. It is held so that it can be opened alternately in a common space, and one hole corresponding to the space is provided in the device frame, and the unit and paper guide can be moved from that hole. And an image forming apparatus. 4. The image forming apparatus according to claim 4, wherein the paper path section from the paper guide to the recording unit can be opened by moving the unit and the paper guide. 5. An image forming apparatus according to claim 4, further comprising a storage member for storing the remaining toner, wherein the storage member can be taken out from the apparatus main body through a moving range of the unit and the paper guide. apparatus.