JP2001130840A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide compact construction by eliminating the need for an auxiliary carrying passage for carrying sheet in both-side printing and improve the reliability of feeding performance in refeeding sheet. SOLUTION: A sheet feed port 41 communicating with an imaging part 2 is provided in a sheet discharging part 4 under a sheet discharge port 24. A sheet refeeding part 40 consisting of a pair of rollers 50 is provided to be movable between the discharge port 24 and the feed port 41. When discharged from the discharge port 24, printed sheet is held with the rear end interposed between the rollers 50. In such a state, the rollers 50 are moved to the feed port 41 and the sheet is fed from the feed port 41 for both-side printing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a printer or a copying machine capable of forming (printing) an image on one side or both sides of a sheet or a sheet.

[0002]

2. Description of the Related Art In a conventional image forming apparatus capable of performing double-sided printing, as shown in FIG.
A main transport path A for transporting the sheet along the image forming process is provided, and a sub transport path B for guiding the sheet printed on one side to the main transport path A again is provided.

[0003]

In the above-described image forming apparatus capable of printing on both sides, when a paper jam (paper jam) occurs in the main conveyance path or the sub conveyance path, a part of the cabinet is opened. Then you have to remove the paper. Therefore, Japanese Patent Publication No. 8-18724
Japanese Patent Application Laid-Open No. 1-92135 discloses an opening / closing mechanism so that a unit formed of members constituting each transport path can be opened from the side of the cabinet in order to eliminate a paper jam in each transport path. It is disclosed that the main conveyance path and the sub conveyance path are respectively opened.

However, in recent years, in order to reduce the size of the apparatus and the area occupied by the apparatus, the image forming apparatus has been made vertical and the front access method has been adopted. If such an image forming apparatus is provided with an opening / closing mechanism for opening the side surface, a problem arises in the operability of the user depending on the location of the apparatus, and the effect of the vertical formation is reduced. Moreover, the opening / closing mechanism complicates the device.

Further, since a sub-transport path must be formed in the cabinet, a space corresponding to the sub-transport path is required, which hinders compactness. Furthermore, since the transport path can be opened, the transport roller and the pressure roller in the transport path are separated from each other, making it difficult to accurately maintain the dimensional accuracy of each roller.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a more compact image forming apparatus capable of performing double-sided printing without a sub-conveying path and using only a main conveying path.

[0007]

The object of the present invention is to provide a sub-transport for double-sided printing by using a paper discharge section from which printed paper is discharged as a paper supply section for performing double-sided printing. A paper feed port for feeding paper to the main transport path (paper transport path) is formed in the paper discharge section, and the paper feed port is disposed below the paper discharge port. The paper re-feeding section is provided so that the paper discharged from the paper output port can be guided toward the paper feeding port using the space of the paper discharging section. The paper re-feeding unit has a paper discharging function as well as a paper feeding function.

As a result, a sheet on which single-sided printing has been performed, for example, a sheet on which backside printing has been performed, is discharged to the sheet discharging section with the front side up by the re-feeding section. At this time, the sheet re-feeding unit does not completely discharge the sheet, holds the rear end, and moves toward the sheet feeding port as it is. Then, the paper is fed from the paper feed port to the main transport path with the front side facing up by the re-feeding unit, and is printed on the front side to perform double-sided printing.

That is, the paper discharge section forms a part of the sub-transport path for transporting the paper to the image forming section, and since this transport path is located outside the cabinet instead of inside, the cabinet is made compact. it can. In addition, since the discharged paper is held and carried to the paper feed port while being held, the paper can be reliably fed, and paper jams in the sub-transport path can be almost eliminated.

Here, a known transport mechanism such as a pair of rollers or a belt can be used as the re-feed section. Therefore, if a roller is used, it is mechanically simple and requires less space. Further, a driving unit for applying a rotational driving force to each roller may be provided integrally with the paper re-feeding unit. However, the driving unit is separated and provided near the paper feeding port and the paper discharging port, respectively. The structure of the paper section can be made compact and simple, so that the moving mechanism for moving the paper re-feeding section can be simplified, and the paper section can be moved quickly.

The driving force is transmitted from the driving section to the rollers by a plurality of gears. If a one-way clutch is provided in the driven gear on the roller side, one roller is driven to rotate and the other roller is driven. Since the rotation is driven, the paper can be smoothly supplied and discharged. Alternatively, instead of providing the one-way clutch, the gears on the roller side may be shifted in the axial direction. As a result, the driving force can be transmitted to one of the rollers, and the other roller is driven and rotated because the driving force is not directly transmitted, so that the paper can be smoothly fed and discharged. Alternatively, an intermediate gear meshing with the driven gear is provided so that the driving force is transmitted to only one of the rollers, and the driving gear is meshed with the intermediate gear. With this configuration, one roller is always driven to rotate, and the other roller does not become a load for rotation, so that the paper can be smoothly fed and discharged.

Further, since the re-feed section moves, there is a problem in meshing the gear on the driving side with the gear on the roller side. However, by making the driving side gear an oscillating idle gear, smooth operation is achieved. Can engage.

By the way, if the moving distance of the paper re-feeding unit is shortened, the time required for the movement can be reduced, and the printing time can be shortened. Therefore, it is preferable to make the paper feed port approach the paper discharge port. At this time, if the re-feed unit is swung, the paper feed port can be brought as close as possible to the paper discharge port.
The moving time can be further reduced, and high-speed printing can be achieved.
Along with this, the height from the bottom surface of the paper discharge unit to the paper feed port is increased, so that the amount of stored paper can be increased,
The original function of the paper discharge unit can also be improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) As shown in FIG. 1, an image forming apparatus capable of performing double-sided printing according to a first embodiment includes a scanner unit 1, an image forming unit 2, a paper feeding unit 3, The unit 4 and the like are provided in the cabinet 5. Scanner unit 1
Has a platen 6 and a scanner optical system 7,
Is made of transparent glass or the like, and is disposed on the upper surface of the cabinet 5. The scanner optical system 7 includes the platen 6
, And comprises an exposure light source 8, a reflecting mirror 9, an imaging lens 10, a photoelectric conversion element (CCD) 11, and the like.

When an original is placed on an original table 6 and the original is irradiated with light from an exposure light source 8, the emitted light is reflected by the original, and the light is reflected by a reflecting mirror 9. The light is focused by the imaging lens 10 arranged in the optical path. The condensed light passes through the imaging lens 10 and is guided to the CCD 11, and original image information converted into an electric signal is obtained.

The image forming section 2 includes a laser scanning unit (LSU) 12, a photosensitive member 13, a developing device 14, a transfer charger 15, a cleaning device 16, a main charger 17, a fixing device 18, and the like. LSU12 is
Based on image data read by the CCD 11 and subjected to image processing by the image processing unit of the control device, a laser beam is irradiated on a laser irradiation point on the surface of the photoconductor 13 to form an electrostatic latent image. The photoconductor 13 is a drum-shaped image carrier that is driven to rotate in a predetermined direction. The surface of the photoconductor 13 is charged to a predetermined potential by the main charger 17, and an electrostatic latent image is formed on the surface by exposure of the LSU 12. . Developing device 14
Develops the electrostatic latent image on the surface of the photoconductor 13 into a visible image with toner. The transfer charger 15 transfers the toner image on the photoconductor 13 to a sheet. The cleaning device 16 removes the toner remaining on the surface of the photoconductor 13 after the transfer. The fixing device 18 fixes the toner image transferred to the sheet.
Then, the developing device 14, the transfer charger 15, the cleaning device 16, and the main charger 1 are arranged around the photoconductor 13 along the rotation direction from the laser irradiation point on the surface of the photoconductor 13.
7 are arranged in order, and a fixing device 18 is arranged downstream of the photoconductor 13 in the sheet conveying direction.

The paper feed unit 3 is provided below the image forming unit 2 and includes a paper cassette 20 detachable from the cabinet 5, a half-moon roller (pickup roller) 21, a transport roller, a registration roller 22, and the like. The manual feed tray 23 for manually feeding paper is located at a position facing
Is provided.

The paper discharge unit 4 is for stacking and storing sheets discharged from a paper discharge port 24 formed in the cabinet 5, and is a space formed outside the cabinet 5, that is, a side of the image forming unit 2. , An image forming unit 2, a sheet feeding unit 3, which is located above the sheet feeding unit 3 and below the scanner unit 1.
The space surrounded by the scanner unit 1 is used as a sheet storage space, and the front side is open, so that the sheet can be taken out therefrom. Note that the paper discharge unit 4 may be provided inside the cabinet 5 without being exposed to the outside.

A main transport path 26 from the paper feed unit 3 to the paper discharge unit 4 via the image forming unit 2 is formed, and the paper on which printing is performed is transported to the photoconductor 13 and discharged. It is a route for. The half-moon roller 2 moves downstream from the paper cassette 20 located upstream of the main transport path 26 in the transport direction.
1. Pre-registration detection switch 27, registration roller 2
2. The photosensitive member 13 and the transfer charger 15 of the image forming section 2, the fixing device 18, the fixing paper detection switch, the transport roller 28, and the paper discharge detection switch 29 are arranged in this order. In the drawings, some switches are omitted and not shown.

The paper stored in the paper cassette 20 is fed to the main transport path 26 by the half moon roller 21, and when the pre-registration detection switch 27 detects the passage of the paper, the registration roller 22 outputs the output of the pre-registration detection switch 27. The paper is conveyed between the photoconductor 13 and the transfer charger 15 at the timing of forming the toner image on the photoconductor 13 based on the signal. The toner image transferred to the sheet by the transfer charger 15 is fixed on the sheet by passing between the upper fixing roller and the lower fixing roller of the fixing device 18. The fixing paper detection switch detects that the paper has passed through the fixing device 18, and the discharge detection switch 29 detects the paper discharge port 2.
4 is detected that the sheet has arrived.

Here, in the present image forming apparatus, in order to perform double-sided printing, instead of eliminating the conventional sub-conveying path,
A sheet re-feeding unit 40 is provided for feeding a sheet printed on one side and discharged to the sheet discharging unit 4 to the image forming unit 2 again. That is, the paper discharge unit 4 is used as a part of the sub-transport path.

A paper feed port 41 is formed in the paper discharge section 4 below the paper discharge port 24. A re-feeding path 42 is formed from the sheet feeding port 41 to the registration roller 22 through the space between the image forming section 2 and the sheet feeding section 3, and merges with the main conveyance path 26 downstream of the registration roller 22. Paper feed port 4 of refeed path 42
In the vicinity of 1, a paper feed detection switch 43 is arranged to detect the passage of the fed paper. Further, a step 44 is formed between the paper feed port 41 and the bottom surface of the paper discharge unit 4 to prevent the discharged paper from entering the paper feed port 41.

The paper re-feeding section 40 has a function of discharging paper from the main transport path 26 and a function of transporting the paper to the paper re-feeding path 42. The transported sheet is transported to the main transport path 26 by the transport roller 45. Then, the re-feeding unit 40 is connected to the paper discharge port 24 and the paper
1 and a driving unit that applies a driving force for conveying the sheet to the sheet re-feeding unit 40.

As shown in FIG. 2, the re-feeding section 40 has a pair of upper and lower rollers 50, and each roller shaft 51
2 are rotatably supported, and driven gears 53 are respectively attached to ends of the respective roller shafts 51, and these are integrally unitized. Then, as shown in FIG. 3, both roller shafts 51 are connected by a pressure spring 54,
The zeros are pressed against each other with a predetermined load, and the driven gear 53 also meshes. An opening is formed in the frame 52 so that the sheet can pass through.

The moving section is a general one using a belt 55 or a chain. Both sides of the frame 52 are fixed to a belt 55 wound around a pair of upper and lower pulleys 56 disposed on both left and right sides. A pulley gear 57 coaxial with 56 is engaged with a motor gear 59 of a moving motor 58 mounted in the cabinet 5. Moving motor 5
As the belt 8 rotates forward and backward, the belt 55 rotates in the up-down direction, and the re-feeding unit 40 is moved up and down.

A position sensor 60 is provided to stop the sheet re-feeding section 40 at a position facing the sheet discharge port 24 and the sheet supply port 41. The position sensor 60 is composed of an optical sensor arranged near the paper discharge port 24 and the paper supply port 41, and a protrusion 61 for turning the position sensor 60 on and off is formed on the frame 52. As a result, the control device controls the driving of the moving motor 58 of the moving unit based on the detection signal from the position sensor 60, so that the rollers 50 of the re-feeding unit 40 Accurate positioning.

As shown in FIG. 4, the drive section drives the roller 50 to rotate by a drive motor 62. The drive section 62 and the sheet discharge port 24 are driven so that the motor gear 63 of the drive motor 62 meshes with the driven gear 53. Each of them is arranged in the cabinet 5 near the opening 41. When the re-feed unit 40 is located at the discharge port 24, the motor gear 63 of the discharge drive unit meshes with the upper driven gear 53 so that the sheet can be discharged. Motor gear 63
Are meshed with the driven gear 53 on the lower side, and the paper can be fed. The lower roller 50 rotates following the rotation of the upper roller 50 by the operation of the paper discharge side driving unit, and the paper is discharged from the paper discharge port 24.

When performing double-sided printing, the rear end of the paper passes through the paper discharge detection switch 29 so that the rear end of the paper is held between the rollers 50 without completely discharging the paper. The control is performed to stop the drive motor 62 at a predetermined timing from the start, or to stop the drive motor 62 at a predetermined timing according to the paper size after the leading end of the paper passes the paper discharge detection switch 29.

Next, the printing operation will be described. First,
When performing one-sided printing, unprinted paper S is taken out of the paper cassette 20 one by one into the main transport path 26 by the half-moon roller 21 and fed to the registration roller 22. Paper S temporarily stopped by registration roller 22
Is transported at the timing when the leading edge of the toner image on the photoconductor 13 and the leading edge of the paper S match, and the transfer charger 15 transfers the toner image on the photoconductor 13 to the paper S by electrostatic force.
Transfer onto one side of After that, the fixing device 18 fixes (fixes) the toner to the sheet S.

The paper S printed on one side, for example, the back side,
The paper is discharged from the paper discharge port 24 to the paper discharge unit 4 by the rollers 50 with the back side, which is the printing surface, facing down. At this time, as shown in FIG. 5A, the sheet re-feeding unit 40 remains at the sheet discharge port 24. The surface to be printed is the image forming unit 2
Depending on the arrangement location, there is also a case where printing is performed not only on the back surface but also on the front surface and discharged.

The paper S discharged from the paper discharge port 24 by the rotation of the roller 50 falls in the space by its own weight, is placed on the bottom surface of the paper discharge unit 4 with its back face down, and is stacked one by one. . The paper S fed from the manual feed tray 23 is transferred and fixed in the same process, and is stored in the paper discharge unit 4. Then, the paper S on which the back surface printing has been performed can be taken out from the front side of the paper discharge unit 4.

In the case of performing double-sided printing, for example, when a command for double-sided printing is input to the control device from an operation key, when the paper S having the back side printed as described above is discharged from the paper discharge port 24, The drive motor 62 is stopped at a predetermined timing after passing through the discharge detection switch 29, and the rear end of the sheet S is held in a state sandwiched by the rollers 50.

Then, as shown in FIG. 5B, the moving motor 58 is operated, and the sheet re-feeding unit 40 descends while the sheet S is sandwiched, and stops when the sheet re-feeding unit 40 is located at the sheet feeding port 41. Then, the lower driven gear 53 meshes with the motor gear 63 of the paper discharge side driving unit.

Thereafter, the drive motor 62 of the sheet discharge side drive unit is driven in accordance with the timing of image formation on the photoconductor 13, and the sheet S is sent out from the sheet feeding port 41 to the sheet re-feeding path 42. When the sheet S reaches the registration roller 22 and is conveyed at a predetermined timing, the unprinted surface becomes the photosensitive member 1.
3 so that printing is performed on this surface and double-sided printing is performed.

At this time, as shown in FIG. 6, the paper S advances in the re-feeding path 42, and the trailing end thereof is
After passing through 3, the moving motor 58 is operated, and the re-feeding unit 40 is raised to the discharge port 24 during printing. The paper S printed on both sides is discharged from the paper discharge port 24,
The sheets fall onto the bottom surface of the sheet discharge unit 4 and are stacked.

Therefore, by providing the re-feeding section 40 for double-sided printing in the paper discharge section 4 and using the paper discharge section 4 as a sub-conveyance path, a sub-conveyance path for performing double-sided printing as in the related art is provided. This eliminates the necessity of providing the apparatus, thereby making the entire apparatus compact and eliminating the need for a member for switching the transport path, thereby simplifying the structure and control.

Further, since the re-feeding path 42 from the sheet feeding port 41 to the image forming section 2 can be shortened, the occurrence of paper jams is greatly reduced, and the reliability of the sheet feeding performance during double-sided printing can be improved. it can. In addition, the discharged sheet S is
By moving the paper to the paper feed port 41 while holding the paper, it is possible to re-feed quickly and eliminate paper feed errors.
Efficient double-sided printing becomes possible.

(Second Embodiment) In this embodiment, as shown in FIG. 7, a one-way clutch 70 is interposed between a roller shaft 51 and a driven gear 53, and one roller 50 is driven to rotate. At this time, when the driven gear 53 of the other roller 50 idles, the other roller 50 is smoothly driven and rotated. In other words, the paper is
When the sheet is conveyed, the other roller 50 that is not driven becomes a resistance to prevent the sheet from being conveyed smoothly.

As shown in FIGS. 7 to 9, the driving force from the driving motor 62 is directly applied to the driven re-feeding unit 40 by a driven gear, as shown in FIGS. The transmission is not performed to the gear 53 but to a plurality of gears. That is, the idle gear 71 includes an idle gear 71 that meshes with the driven gear 53, and a pair of pulley gears 72 and a belt 73 that transmit the driving force from the drive motor 62 to the idle gear 71. The other pulley gear 72 is meshed with the idle gear 71, and the driving force from the drive motor 62 is transmitted to the idle gear 71 via the pulley gear 72 and the belt 73, and transmitted from the idle gear 71 to one driven gear 53. .

The drive motor 62 is, as shown in FIG.
At the vicinity of the paper discharge port 24 and the paper supply port 41, they are mounted on the rear side inside the cabinet 5 by mounting plates 74, respectively.
One pulley gear 72 is rotatably supported by the mounting plate 74. The other pulley gear 72 is rotatably supported by a support shaft 75 attached to the cabinet 5, and a fan-shaped pendulum plate 76 is rotatably supported by the support shaft 75. On this pendulum plate 76, the idle gear 71 is
7, and is rotatably supported around the idle gear 71.
Are swingable about the support shaft 75.

A spring 78 is interposed between the pendulum plate 76 and the mounting plate 74 to urge the pendulum plate 76 away from the sheet re-feeding unit 40, that is, to push the idle gear 71 against the driven gear 53. are doing. Here, a stopper 79 that regulates the movement of the pendulum plate 76 is provided to prevent the idle gear 71 from swinging too much and becoming out of mesh with the driven gear 53, so that reliable meshing can be obtained.

Here, the center shaft 77 of the idle gear 71
Is the roller shaft 5 between the support shaft 75 and the roller shaft 51.
It is arranged so as to be shifted toward the support shaft with respect to the extension line in the movement direction of (1). Such a positional relationship between the gears enables the idle gear 71 to smoothly mesh with the moving driven gear 53, thereby preventing damage such as gear tooth jumps and reducing the rotational load torque.

The other structure is the same as that of the first embodiment, and the printing operation is the same.
Here, transmission of the driving force to the re-feed unit 40, which is a feature of the present embodiment, will be described. When the printed sheet is discharged from the paper discharge port 24, the re-feeding unit 40
And the upper driven gear 53 is the idle gear 7
1 is pushed up slightly, but the two gears 53 and 71 are meshed by the urging force of the spring 78.

Then, the pulley gear 72 rotates, the idle gear 71 rotates, the further driven gear 53 rotates, and the upper roller 50 rotates by the operation of the drive motor 62 on the paper discharge side. The lower driven gear 53 meshing with the upper driven gear 53 also rotates, but the one-way clutch 70
As a result, the lower roller shaft 51 does not rotate, and the driving force is not transmitted to the lower roller 50. However, the lower roller 50 rotates following the rotation of the upper roller 50. As a result, the paper is smoothly discharged from the paper discharge port 24.

When performing double-sided printing, the rotation of the roller 50 is stopped in a state where the rear end of the paper is sandwiched without completely discharging the paper. Thereafter, the moving motor 58 is operated, and the roller 50 descends to the paper feed port 24 while holding the paper, and stops at the fixed position. Then, as shown in FIG. 8, the lower driven gear 53 is engaged with the idle gear 71 on the paper feed side, and the paper can be fed. Subsequent operations are performed in the same manner as described above, paper is fed, and double-sided printing is performed.

(Third Embodiment) In the present embodiment, FIG.
, The upper driven gear 53 and the lower driven gear 5
3 are displaced in the axial direction and do not mesh with each other. As shown in FIGS. 12 to 15, idle gears 71 are provided so as to mesh with the respective driven gears 53, and the other configuration is the same as that of the second embodiment except for the one-way clutch. In such a structure, a one-way clutch is not required, so that the mechanism of the drive unit is simplified.

In this configuration, when the paper is discharged from the paper discharge port 24, as shown in FIGS.
0 is located at the discharge port 24, and the idle gear 71 is meshed with the upper driven gear 53. Then, by the operation of the drive motor 62 on the sheet discharging side, the driving force is transmitted from the idle gear 71 to the driven gear 53, and the upper roller 50 rotates. On the other hand, no driving force is transmitted to the lower driven gear 53, but the lower roller 50 pressed against the upper roller 50 is driven to rotate. As a result, the paper is smoothly discharged from the paper discharge port 24.

In the case of performing double-sided printing, the rotation of the roller 50 is stopped with the rear end of the paper being sandwiched without completely discharging the paper, and the paper is lowered to the paper feed port 41 as it is. Then, as shown in FIGS. 14 and 15, the lower driven gear 53 is engaged with the idle gear 71 on the paper feed side, and the driving force of the drive motor 62 is transmitted to the roller 50 as described above, and the paper can be fed.

(Fourth Embodiment) In this embodiment, FIG.
As shown in FIG. 7, an intermediate gear 80 meshing with the upper driven gear 53 is provided, and the intermediate gear 80 meshes with the idle gear 71 on the paper discharge side and the paper supply side. The intermediate gear 80 is connected to the frame 5
2 is rotatably supported by a shaft 81 attached to the shaft 2 and is formed wide in the axial direction. The driven gear 53 is not provided on the lower roller 50, and the driven roller 53 is not provided on the lower roller 50.
0 is always driven to rotate. Other configurations are the same as those of the third embodiment.

In this configuration, when the re-feeding section 40 is located at the paper discharge port 24 or the paper supply port 41, when
As shown in FIG. 8, the intermediate gear 80 meshes with the idle gear 71. The driving force from the driving motor 62 is the idle gear 7
1, transmitted to the upper driven gear 53 via the intermediate gear 80. Then, the upper roller 50 is rotated, and accordingly, the lower roller 50 is driven to rotate, and the paper can be discharged or fed.

As described above, by using the intermediate gear 80, the engagement with the idle gear 71 is reliably performed when the re-feed unit 40 moves. Therefore, it is not necessary to make the position accuracy of the gear strict, and the mounting work becomes easier. Furthermore, parts such as a one-way clutch are not required, and an inexpensive mechanism can be obtained.

(Fifth Embodiment) In this embodiment, FIG.
As shown in FIGS. 9 and 20, the paper feed port 41 is formed so as to be closer to the paper discharge port 24 than in the above-described embodiments. The main transport path 26 leading to the paper discharge port 24 is slightly inclined downward in the discharge direction, and the re-feed path 42 from the paper supply port 41 is slightly downwardly inclined in the paper supply direction. And the extension lines in each direction intersect at one point. The configuration of the sheet re-feeding unit 40 and the driving unit is any of the above-described embodiments, and the other configurations are the same as those of the first embodiment.

As described above, the paper feed port 41 and the paper discharge port 24
By disposing them close to each other, the distance between them is reduced, so that the moving time of the re-feeding unit 40 can be reduced, and the speed of double-sided printing can be increased. Therefore, when two-sided printing is performed on a long sheet, the sheet is fed, the trailing edge of the sheet passes through the sheet feed detection switch 43, and then the sheet is re-fed until the leading end of the printed sheet reaches the sheet discharge port 24. The unit 40 is the paper discharge port 2
4 can be completed, the sheet is reliably discharged by the roller 50, and a paper jam in the middle of discharging and a disorder of the stacked state of the discharged sheet can be eliminated.

Further, since the paper discharge port side of the main transport path 26 and the paper supply port side of the re-feed path 42 are respectively formed to be inclined, the paper can be discharged and fed smoothly. Further, since the distance from the bottom surface of the paper discharge unit 4 to the paper feed port 41 becomes large, the height of the step can be increased and the amount of stored paper can be increased.

By the way, the paper re-feeding section 40 moves linearly in the vertical direction, but as shown in FIG. 21, the paper re-feeding section 40 moves along an arc centered at the intersection of each extension line. It may be. For example, the frame 52 is
Is provided, the frame 52 moves along the guide rail. Thus, the re-feeding unit 40
Is moved, the straight line connecting the centers of the upper and lower rollers 50 is orthogonal to the discharge direction or the paper supply direction, so that the transport direction by the pair of rollers 50 can be made to coincide with the traveling direction of the paper. The roller 50 smoothly enters the nip of the roller 50, and also smoothly enters the paper feed port 41, so that a discharge failure or a paper supply failure does not occur.

Further, since the sheet storage capacity can be increased, it is preferable to provide an expandable paper discharge tray 82 in the paper discharge unit 4 as shown in FIG. As the paper discharge tray 82, a part of the outer side wall of the paper discharge unit 4 may be opened and closed freely, and the area of the bottom surface is expanded. Used as a tray 82. Alternatively, a slidable paper discharge tray 82 is provided on the bottom surface without providing a side wall, and is pulled out and used as needed.

Further, as shown in FIG. 23, near the roller 50 of the paper re-feeding section 40, for example, on the side facing the wall surface of the paper discharge section, a paper sensor such as an optical sensor for detecting the paper A detection switch 83 may be provided. The paper detection switch 83 fulfills the function of the paper ejection detection switch 29 when the re-feed unit 40 is located at the paper exit 24, and fulfills the function of the paper feed detection switch 43 when the re-feed unit 40 is located at the paper exit 41. It also functions as a switch. It should be noted that a flexible wiring board is connected to the paper detection switch 83 so that a signal can be output even when the paper detection switch 83 moves. Therefore,
There is no need to provide two switches in the cabinet 5, and the number of components can be reduced and space can be saved.

(Sixth Embodiment) In the present embodiment, FIG.
As shown in FIGS. 4 and 25, the paper discharge port 24 and the paper supply port 41 are further brought closer to each other, and the main transport path 26 leading to the paper discharge port 24 is formed.
Is slightly inclined downward as in the fifth embodiment, and the re-feeding path 42 has a shape curved upward toward the discharge port 24. Then, the paper is discharged and fed by moving the re-feeding unit 40 to swing freely.

The configuration of the paper re-feeding section 40 is any of the above-described embodiments, and the frame 52 is supported by the cabinet 5 so as to be rotatable around a support shaft 85. When the support shaft 85 is integrally attached to the frame 52 as a moving unit, a motor is used and the support shaft 85 is rotated to rotate the paper refeeding unit 40. When the support shaft 85 is attached to the cabinet 5 and the frame 52 is rotatably supported by the support shaft 85, a solenoid
Rotate 2 directly. As in the above embodiments, two driving units are provided, or a driving motor 62 is attached to the frame 52, and the roller shaft 51 is directly driven to rotate so that the roller 50 rotates forward and backward. Other configurations are first
This is the same as the embodiment.

At this time, since the paper re-feeding section 40 rotates near the side wall of the paper discharging section 4, the re-feeding section 40 is rotated between the paper discharging port 24 and the paper feeding port 41 so that the frame 52 can rotate without contacting the wall surface. The wall is concave. Since a gap is formed between the frame 52 and the wall surface, a guide piece 86 is formed on the frame 52 in order to fill the gap and smoothly advance the sheet. Further, the paper feed port 41 is larger than the paper discharge port 24 and is opened so as to expand toward the support shaft 85, so that paper can easily enter.

In the above configuration, when the sheet re-feeding section 40 faces the sheet discharge port 24, the straight line connecting the centers of the upper and lower rollers 50 is orthogonal to the discharge direction, so that the sheet is Smoothly into the roller 5
It is discharged by zero forward rotation. In the case of double-sided printing, when the sheet re-feeding unit 40 rotates with the rear end of the sheet sandwiched therebetween and faces the sheet feeding port 41, the sheet is fed to the sheet feeding port 41 by the reverse rotation of the roller 50. It is.

According to this, the distance from the bottom surface of the paper discharge unit 4 to the paper feed port 41 is increased, so that the amount of stored paper can be further increased. Further, the moving time of the sheet re-feeding unit 40 is further reduced, and the speed can be further increased.

Note that the present invention is not limited to the above embodiment, and it goes without saying that many modifications and changes can be made to the above embodiment within the scope of the present invention. For example, if a vacuum suction type conveyance belt is used instead of the roller of the paper re-feeding unit, the sheet can be held by suction while the sheet is conveyed. Further, a drive motor may be provided in the re-feeding unit, and the rollers may be directly driven to rotate. As the moving unit, a rack and pinion may be used instead of using a belt.

Further, a second paper discharge unit is provided in addition to the paper discharge unit, so that the paper printed on both sides is discharged to the second paper discharge unit, and the paper printed on one side is discharged to the paper discharge unit. Providing a means for switching the discharge direction enables continuous printing of the same image on a plurality of sheets, which is useful when performing double-sided printing of a plurality of copies. Furthermore, a new sheet can be stored in the sheet discharging unit, and the printed sheet can be discharged to the second sheet discharging unit, so that the sheet discharging unit can be used as a sheet feeding unit.

[0065]

As is apparent from the above description, according to the present invention, a paper feed port is formed in the paper discharge section, and the paper discharged from the paper discharge port is moved to the paper feed port by moving the re-feed section. By performing the guidance, the paper discharge unit becomes a part of the transport path, and double-sided printing can be performed. Therefore, by using the existing paper discharge unit, it is not necessary to provide the sub-transport path in the cabinet, and the entire apparatus can be made compact and simple.

Since the movable paper re-feeding unit has both a paper discharging function and a paper feeding function, it is not necessary to separately provide a paper discharging roller, a paper feeding roller, and the like, and the apparatus can be made compact. Further, since the sheet can be reliably guided to the sheet feeding port and sent out, it is possible to prevent a paper jam or a sheet feeding failure.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a refeeding unit and a moving unit;

FIG. 3 is a diagram illustrating rollers of a paper re-feeding unit.

FIG. 4 is a front view and a side view showing states of a driving unit at the time of paper ejection and paper feeding.

5A and 5B are diagrams illustrating an operation of a paper re-feeding unit, where FIG.

FIG. 6 is a diagram illustrating an image forming apparatus during duplex printing.

FIG. 7 is a diagram illustrating a driving unit when a re-feed unit according to a second embodiment is positioned at a discharge port;

FIG. 8 is a diagram showing a driving unit when the re-feeding unit is located at the paper feeding port.

FIG. 9 is a plan view of a driving unit.

FIG. 10 is a configuration diagram when the image forming apparatus is viewed from the back side.

FIG. 11 is a diagram illustrating rollers of a paper re-feeding unit according to a third embodiment.

FIG. 12 is a diagram showing a meshing state of gears at the time of paper ejection.

FIG. 13 is a diagram illustrating a driving unit when a paper re-feeding unit is positioned at a paper discharge outlet;

FIG. 14 is a diagram illustrating a meshing state of gears during paper feeding.

FIG. 15 is a diagram illustrating a driving unit when a paper re-feeding unit is positioned at a paper feeding port;

FIG. 16 is a plan view of a driving unit according to a fourth embodiment.

FIG. 17 is a diagram illustrating a driving unit when a paper re-feeding unit is positioned at a paper discharge port;

FIG. 18 is a diagram illustrating a driving unit when a paper re-feeding unit is positioned at a paper feeding port;

FIG. 19 is a configuration diagram of an image forming apparatus according to a fifth embodiment.

FIG. 20 is a configuration diagram of an image forming apparatus when performing double-sided printing.

FIG. 21 is a configuration diagram of an image forming apparatus according to another embodiment.

FIG. 22 is a configuration diagram of an image forming apparatus provided with a discharge tray.

FIG. 23 is a configuration diagram of an image forming apparatus according to another embodiment.

FIG. 24 is a configuration diagram of an image forming apparatus according to a sixth embodiment.

FIG. 25 is a configuration diagram of an image forming apparatus when performing double-sided printing.

FIG. 26 is a diagram illustrating a transport path of a conventional image forming apparatus.

[Explanation of symbols]

 4 Discharge Portion 24 Discharge Port 26 Main Transport Path 40 Refeed Section 41 Paper Feed Port 42 Refeed Path 50 Roller 53 Follower Gear 55 Belt 58 Moving Motor 62 Drive Motor 70 One-Way Clutch 71 Idle Gear 76 Pendulum Plate 80 Intermediate gear

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Atsushi Saito 22-22 Nagaike-cho, Abeno-ku, Osaka-shi Inside Sharp Corporation (72) Inventor Shinji Oishi 22-22 Nagaike-cho, Abeno-ku, Osaka-shi Osaka (72) Inventor Kayoshi Shiraishi 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Sharp Corporation (72) Inventor Yasushi Yasutomo 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Sharp Corporation (72) Inventor Shinichiro Hiraoka 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Inside Sharp Co., Ltd. (72) Inventor Hiroaki Hori 22-22 Nagaikecho, Abeno-ku, Osaka City, Osaka Sharp Co., Ltd. (72) Invention Yosuke Kashu 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka F-term (reference) 2H028 BA06 BA16 BB04 3F100 AA02 CA02 CA 12 DA01 EA03

Claims (17)

[Claims] An image forming section for forming an image on a sheet, a sheet conveying path for conveying the sheet to the image forming section, and a sheet discharging section for accommodating a sheet on which an image has been formed and discharged;
A paper discharge port for discharging paper from the paper transport path and a paper feed port connected to the paper transport path are formed in the paper discharge unit, and the paper discharged from the paper discharge port to perform duplex image formation. Is provided from the paper supply port to the paper transport path, the re-paper supply section is movable between the paper discharge port and the paper supply port, An image forming apparatus having a paper discharging function as well as a paper feeding function. 2. A paper discharge port is disposed above a paper supply port, and a moving unit is provided for moving a paper re-feed unit between the paper discharge port and the paper supply port. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus moves while holding the image. 3. The image forming apparatus according to claim 2, further comprising a position detector for detecting that the re-feed unit has reached a paper discharge port or a paper feed port. 4. The paper re-feeding section has a pair of rotatable rollers, and moves up and down from a paper discharge port toward a paper feed port while holding the paper between the rollers. The image forming apparatus according to claim 2. 5. The image forming apparatus according to claim 4, wherein a driving unit that applies a rotational driving force to each roller is provided in the vicinity of the paper feed port and the paper discharge port. 6. A driven gear is provided for a roller shaft of each roller. One of the driven gears is connected to the paper discharge side drive when the roller moves to the paper discharge port, and the other is driven when the roller moves to the paper discharge port. The image forming apparatus according to claim 5, wherein the driven gear is connected to the sheet feeding side driving unit. 7. A driven gear of each roller shaft is meshed with each other, a one-way clutch is provided for each driven gear, and when one roller is driven to rotate, the other roller is driven and rotated. The image forming apparatus according to claim 6, wherein 8. The apparatus according to claim 1, wherein the rollers are urged in a direction in which the rollers are pressed against each other, the driven gears are arranged offset in the axial direction, and the other roller is rotated by the rotation of one roller. The image forming apparatus according to claim 6. 9. The driving unit has an idle gear that meshes with a driven gear of the roller, wherein the idle gear is swingable about a fulcrum and urged in a direction that meshes with the driven gear. 9. The image forming apparatus according to claim 7, wherein: 10. Each of the rollers is urged in a direction of pressing against each other, and a driven gear attached to a roller shaft of one of the rollers and an intermediate gear meshing with the driven gear are provided. The image forming apparatus according to claim 5, wherein a driving force is transmitted from a driving unit to the driven gear, and the other roller is rotated by rotation of one roller. 11. A drive unit having an idle gear meshing with an intermediate gear, wherein the idle gear is swingable about a fulcrum and urged in a direction meshing with the intermediate gear. The image forming apparatus according to claim 10. 12. The idle gear according to claim 9, wherein a center axis of the idle gear is attached to a pendulum plate that swings around a fulcrum, and the center axis is offset from the roller axis toward the fulcrum. Or the image forming apparatus according to 11. 13. A step is formed between the bottom surface of the paper discharge unit and the paper feed port to prevent the accommodated paper from entering the paper feed port, and a step is formed when one-sided image formation is performed. The image forming apparatus according to claim 2, wherein the sheet feeding unit discharges the sheet while being positioned at a sheet ejection port. 14. The paper discharge port and the paper supply port are brought close to each other so that the extension line in the discharge direction of the paper discharge port intersects with the extension line in the paper supply direction of the paper supply port. Image forming apparatus. 15. The image forming apparatus according to claim 14, wherein the sheet re-feeding unit moves up and down on an arc centered on an intersection of each extension line between the sheet discharge port and the sheet supply port. apparatus. 16. A paper re-feeding section rotatably supported around a support shaft provided near a paper discharge port, and the paper supply port is opened close to the paper discharge port. The image forming apparatus according to claim 2. 17. The image forming apparatus according to claim 14, wherein an expandable paper discharge tray is provided on a bottom surface of the paper discharge unit.