JP3984926B2 - Duplex printing unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine, a printer, or a facsimile using an electrophotographic process, and more particularly to a duplex printing unit used in the image forming apparatus.
[0002]
In general, as an image forming apparatus, after an image is formed (printed) on one side (first side) of a recording sheet by an image forming unit, the image-formed recording sheet is reversed on the first side and the image is again displayed. 2. Description of the Related Art An image forming apparatus is known that forms an image on both sides of a recording sheet by transporting it to a forming unit and forming an image on the other side (second side) of the recording sheet.
[0003]
In order to support double-sided printing, the image forming apparatus is equipped with a double-sided printing unit, and in the double-sided printing mode, the recording paper on which image formation has been performed on one side is sent to the double-sided printing unit, and the double-sided printing unit uses the recording paper. Then, the recording paper is sent again to the image forming unit to form an image on the other side.
[0004]
By the way, in the single-sided printing mode, the recording paper is discharged to a paper discharge tray or the like without sending the recording paper to the double-sided printing unit. There are so-called face-up discharge for discharging paper, and so-called face-down discharge for discharging to the discharge tray with the printing surface facing downward. Similarly, in the case of duplex printing, the second surface is turned upward. When the recording sheet is discharged to the discharge tray, the face-up discharge is performed, and when the second sheet is discharged downward, the face-down discharge is performed.
[0005]
In face-up discharge and face-down discharge, the page order of the recording sheets discharged to the discharge tray is reversed. For this reason, in recent years, there has been known an image forming apparatus in which a user can select face-up discharge or face-down discharge as required.
[0006]
For example, the recording paper that has passed through the fixing unit is discharged face-down onto a paper discharge tray provided at the top of the image forming apparatus main body via a paper discharge path. On the other hand, when performing face-up discharge, the recording paper is discharged to a separately provided face-up tray.
[0007]
However, when the duplex printing unit is attached to the image forming apparatus as described above, the face-up tray may not be used. In order to prevent such a problem, there is known an image forming apparatus in which a double-sided printing unit can be easily attached to the main body of the image forming apparatus and face-up discharge can be performed.
[0008]
Here, when performing double-sided image formation, the face-up tray is closed to a substantially vertical position. As a result, the relay tray is pushed up by the cam member 58, and the recording paper is conveyed to the path 55 formed by the face-up tray and the relay tray.
On the other hand, when performing face-up discharge, the face-up tray is opened at a position close to the horizontal). As a result, the relay tray pushed up by the cam member follows the cam member by its own weight and descends to a position shown in the figure that is substantially parallel to the face-up tray (see Patent Document 1).
[0009]
[Patent Document 1]
JP-A-8-188344 (paragraph (0060) to paragraph (0065), FIGS. 1 to 3).
[0010]
[Problems to be solved by the invention]
By the way, in the image forming apparatus described in Patent Document 1, when the face-up tray is opened, the relay tray pushed up by the cam member becomes substantially parallel to the face-up tray by its own weight, and thereby the recording paper In the face-up state, the sheet is discharged to the face-up tray via the relay tray, but the relay tray needs to be interlocked with the opening and closing operation of the face-up tray. There is a problem that an interlocking mechanism including a cam member or the like is required and the configuration becomes extremely complicated.
[0011]
Furthermore, the image forming apparatus described in Patent Document 1 has a problem that a relay tray is required and the number of parts increases.
[0012]
An object of the present invention is to provide a double-sided printing unit that can perform face-up discharge with a simple configuration when mounted on an image forming apparatus.
[0013]
[Means for Solving the Problems]
According to the present invention, an image forming unit that forms an image on a recording sheet, and a fixing unit that is disposed downstream of the image forming unit and fixes the recording sheet on which the image is formed by the image forming unit. Used together with an image forming apparatus, arranged on the image forming apparatus, receives a recording sheet on which an image is formed on one side through the fixing unit, reverses the surface of the recording sheet, and sends the recording sheet to the image forming unit A double-sided printing unit, a recording sheet reversing unit that reverses the recording sheet and sends the recording sheet to the image forming unit, and a recording that is positioned between the fixing unit and the recording sheet reversing unit and is conveyed from the fixing unit A path defining unit that defines a duplex printing conveyance path for feeding the sheet to the recording sheet reversing unit; the path defining unit projects from one side of the image forming apparatus; The double-sided printing conveyance path is defined in the closed state so as to be rotatable around the fulcrum axis of the sheet, and when the open state is reached, the double-sided printing conveyance path is interrupted in the middle and passes through the fixing unit. A double-sided printing unit is provided that includes a paper discharge receiving member that receives the recording paper in a face-up state.
[0014]
In this way, the path defining portion of the duplex printing unit protrudes from one side surface of the image forming apparatus, and is disposed on the path defining portion so as to be rotatable about a predetermined fulcrum axis. If the paper is provided with a paper receiving member that receives the recording paper that has passed through the fixing unit in a face-up state by blocking the double-sided printing conveyance path in the middle of Even when mounted on the forming apparatus, the recording sheet can be discharged face-up with a very simple configuration.
[0015]
In the present invention, the duplex printing unit can be attached to and detached from the image forming apparatus, and the duplex transport path is positioned on the fixing unit side and extends substantially horizontally, and is positioned on the downstream side of the horizontal portion. An arcuate portion extending in an arcuate shape, and a vertical portion located on the downstream side of the arcuate portion and extending in a substantially vertical direction, and the discharge receiving member corresponds to the horizontal portion and the arcuate portion. The fulcrum shaft is provided corresponding to the lower end of the arcuate portion.
[0016]
As described above, the double-sided conveyance path is positioned on the fixing unit side and extends substantially horizontally, on the downstream side of the horizontal portion, the arc-shaped portion extending in an arc shape, and on the downstream side of the arc-shaped portion. And a vertical portion extending in a substantially vertical direction, and a sheet receiving member is provided corresponding to the horizontal portion and the arc-shaped portion, and a fulcrum shaft is provided corresponding to the lower end of the arc-shaped portion. The recording sheet sent from the fixing unit can be received by the discharge receiving member without opening any other mechanism by simply opening the discharge receiving member.
[0017]
In the present invention, the paper discharge receiving member forms a part of the exterior of the duplex printing unit main body, is formed on the inner surface of the cover that defines the duplex printing conveyance path, and the duplex printing conveyance path And a lower end of the rib portion is located below the fulcrum shaft when the discharge receiving member is closed, and the discharge receiving member is in an open state. When this occurs, the double-sided printing conveyance path is blocked in the middle at the lower end of the rib portion.
[0018]
As described above, the discharge receiving member forms a part of the double-sided printing unit main body exterior, covers that define the double-sided printing conveyance path, and rib portions that are formed on the inner side surface of the cover and extend along the double-sided printing conveyance path And the lower end of the rib portion is positioned below the fulcrum shaft when the discharge receiving member is closed. The double-sided printing conveyance path is interrupted in the middle of the printing paper, so that the recording paper is not inserted into the paper reversing part side.
[0019]
And the inclined part which inclines outside toward the downstream is prescribed | regulated at the lower end part of the rib part in the state which the said paper discharge receiving member was closed, and when the said paper discharge receiving member is in an open state, The inclined portion is inclined upward from the fixing unit side toward the downstream side.
[0020]
In this way, when the discharge receiving member is closed, by defining an inclined portion that is inclined outward toward the downstream side at the lower end of the rib portion, when the discharge receiving member is in the open state, The inclined portion is inclined upward from the fixing unit side toward the downstream side, so that the recording sheet can be discharged smoothly.
[0021]
In the present invention, the double-sided printing unit is provided with detection means for detecting that the paper discharge receiving member is in an open state and sending a cover open signal. A paper discharge path connected to the fixing unit, a paper discharge tray that receives the recording paper face down through the paper discharge path, and a path switch that selectively connects the fixing unit to the duplex printing conveyance path or the paper discharge path. And a control unit that controls the path switching member in response to the cover opening signal to connect the fixing unit and the duplex printing conveyance path.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are not intended to limit the scope of the present invention only to the description unless otherwise specified. It is just an example.
[0023]
First, referring to FIG. 1, the illustrated image forming apparatus is an image forming apparatus using an electrophotographic process, and this image forming apparatus includes a photosensitive drum 11, which is a latent image carrier, a developing device, a charging device, An exposure unit and a cleaning unit (developer, charger, exposure unit, and cleaning unit are not shown) are provided. After the photosensitive drum 11 is charged by the charger, the exposure unit responds to image data. Thus, the photosensitive drum 11 is exposed, and an electrostatic latent image is formed on the photosensitive drum 11. Thereafter, the electrostatic latent image on the photosensitive drum 11 is developed by a developing device to form a toner image.
[0024]
The image forming apparatus main body 10 is detachably mounted with a paper feed cassette 16 containing recording paper. The paper feed cassette 16 is disposed on the front side of the image forming apparatus main body 10 (right side: one side in FIG. 1). It is mounted so that it can be pulled out. One sheet of recording paper loaded in the paper feed cassette 16 is picked up by the pickup roller 16a, reaches the registration roller pair 16d through the paper transport path P by the feed roller pair 16b and the transport roller 16c, and the photosensitive drum. 11 and the nip portion of the transfer roller 17. Then, the toner image on the photosensitive drum 11 is transferred onto a recording sheet to become a transfer image.
[0025]
Thereafter, the recording paper is sent to the fixing unit (fixing roller pair) 18 through the paper conveyance path P, and the transfer image on the recording paper is fixed here. The residual toner remaining on the photosensitive drum 11 is removed by the cleaning unit. An image forming unit is configured by the photosensitive drum 11, the developing device, the charging device, the developing device, the exposure unit, the transfer roller, and the like.
[0026]
In the example shown in FIG. 1, a duplex printing unit (paper reversing unit) 19 is mounted on the lower side of the paper feeding cassette 16, and this paper reversing unit 19 is attached to the image forming apparatus main body 10 on its back side (paper feeding cassette). 16 is attached to the image forming apparatus main body 10 as necessary (that is, the sheet reversing unit 19 is optionally provided later as the image forming apparatus main body 10). Can be incorporated into). If the sheet reversing unit 19 is incorporated in the image forming apparatus main body 10, double-sided printing can be performed on the recording sheet as will be described later.
[0027]
In the illustrated example, one end portion (left end portion in the figure) protrudes from the back side of the image forming apparatus main body 10 with the sheet reversing unit 19 mounted on the image forming apparatus main body 10. In this protruding portion, a conveyance path (double-sided printing conveyance path) R for conveying the paper is defined, and a sheet reversing roller 19b is accommodated in the lower part thereof (hereinafter, this protruding portion is simply referred to as a path defining portion). I will decide). A paper discharge receiving member (cover member) 191 that constitutes a part of the exterior of the duplex printing unit is provided in an upper portion of the path defining portion 19a. When the cover member 191 is opened as described later, A cover member 191 is used as a face-up tray. Further, when the cover member 191 is closed, the cover member 191 constitutes an upper portion of the transport path R and plays a role of protecting the transport path R.
[0028]
Now, when the single-sided printing mode is selected on the operation panel 10a provided in the main body of the image forming apparatus with the cover member 191 closed, the path switching member 21 located at the rear stage of the fixing unit 18 is discharged from the upper discharge tray. The recording sheet sent from the fixing unit 18 at the sheet position passes through the sheet discharge path Q and is discharged face-down to a sheet discharge tray 10b formed on the upper surface of the image forming apparatus main body.
[0029]
On the other hand, when the double-sided printing mode is selected on the operation panel 10a with the cover member 191 closed, the path switching member 21 enters the double-sided printing mode position, and the recording paper sent from the fixing unit 18 passes through the conveyance path R. Then, the sheet is conveyed into the sheet reversing unit 19.
[0030]
When the recording paper is transported to the transport path R, the recording paper is detected by a reverse paper detection sensor (not shown), and the control device (not shown) drives the paper reverse roller 19b to rotate in the direction indicated by the solid line arrow. Control. As a result, the recording sheet is conveyed along a path indicated by a solid arrow and reaches a path (hereinafter referred to as a reverse path) S.
[0031]
When a recording sheet is detected by a sheet detection sensor (not shown) arranged in the reversing path S, the control device controls the rotation of the sheet reversing roller 19b in the direction indicated by the broken line arrow. As a result, the recording paper is sent from the reversing path S in the direction indicated by the broken-line arrow, and is transported by the transporting roller 19e through the path (hereinafter referred to as the reversing path) T, and reaches the above-mentioned paper transporting path P. 16d is reached.
[0032]
A paper detection sensor (not shown) is disposed in the reversing path T. When the paper is detected by the paper detection sensor, the photosensitive drum 11 is driven to rotate and charge and expose as described above. Is started. Thereafter, as described above, the toner image on the photosensitive drum 11 is transferred to the other surface of the recording paper and fixed by the fixing unit 18. Then, the recording paper subjected to double-sided printing passes through the paper discharge path Q to the paper output tray 10b formed on the upper surface of the image forming apparatus main body by the path switching member 21 returned to the upper surface paper discharge tray paper discharge position. Paper.
[0033]
Here, referring to FIG. 2, in FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals. As shown in the figure, on the downstream side of the fixing unit 18 (not shown in FIG. 2), the paper transport path P branches into a paper discharge path Q and a transport path R. Is arranged, and the above-described path switching member 21 is arranged.
[0034]
Referring also to FIG. 3, the above-described transport path R is defined by a cover member 191 and a path defining member (conveying rib member) 32 facing the cover member 191, and the path defining member 32 is substantially vertical. It has a vertical surface (vertical surface) 32a extending, an arcuate surface 32b, and a horizontal surface 32c extending substantially in the horizontal direction, and one end (right end in FIG. 2) of the horizontal surface 32c reaches the aforementioned branch point.
[0035]
On the other hand, the cover member 191 includes a cover 192 formed in a substantially arc shape, and a plurality of ribs 33 projecting in a direction perpendicular to the inner side surface on the inner side surface of the cover 192 and extending in an arc shape along the transport path R. Is formed. The cover member 191 is disposed above the arcuate surface 32b corresponding to the arcuate surface 32b described above, and one end (the lower end in FIG. 2) of the cover member 191 with respect to the fulcrum shaft 34 provided in the path defining portion 19a. It is free to rotate.
[0036]
The lower end of the rib 33 is located below the fulcrum shaft 34 in a state where the cover member 191 is closed, and the inclined side 35 is inclined from the lowest point toward the upstream side of the transport path R. Is formed. That is, an inclined side 35 that is inclined from the lowest point toward the route defining member 32 is formed at the lower end of the rib 33 (in other words, at the lower end of the rib 33 with the cover member 191 closed). An inclined side 35 that is inclined outward toward the downstream side is defined).
[0037]
Then, as will be described later, when the cover member 191 is rotated around the fulcrum shaft 34 and the cover member 191 is opened, the conveyance path R is blocked by the lower ends of the ribs 33.
[0038]
As shown in FIG. 3, hook portions 191a are formed at both end portions of the cover member 191, and when the cover member 191 is closed, the cover member 191 is held by the path defining portion 19a by the hook portion 191a. Will be.
[0039]
Here, referring to FIG. 3 and FIG. 4, when the user wants to perform face-up discharge in single-sided printing, the user selects the single-sided printing mode by the mode operation panel and the user presses the cover member 191. When the cover member 191 is opened by rotating around the fulcrum shaft 34 (in this case, the cover member 191 is stopped at a predetermined rotation angle by a stopper (not shown) as shown in FIG. 3). A cover opening signal indicating that the cover is open is provided to the control device from a cover opening / closing detection sensor (not shown). When the control device receives the cover opening signal when the single-sided printing mode is selected, the control device positions the path switching member 21 at the double-sided printing mode position.
[0040]
As described above, the recording paper on which an image is formed on one side by the image forming unit passes through the fixing unit 18 and reaches a branch point. At this time, since the path switching member 21 is in the double-sided printing mode position, the recording paper is sent to the transport path R side without being sent to the paper discharge path Q side. Since the cover member 191 is open, the recording paper ST is discharged face-up onto the inner surface of the cover member 191 from the middle of the transport path R.
[0041]
When the recording paper is discharged to the cover member 191, the lower end of the rib 33 blocks the conveyance path R, and as described above, the inclined side 35 is formed at the lower end of the rib 33. When the cover member 191 is opened, as shown in FIG. 3, the inclined side 35 is inclined upward from the upstream side toward the downstream side, and the recording paper ST is smoothly faced to the cover member 191. Can be ejected up.
[0042]
Further, as shown in FIG. 5, even when the recording sheet ST after passing through the fixing unit 18 is curled downward, the conveyance path R is blocked by the lower end of the rib 33. The recording paper ST does not enter the reversing path S side, and the inclined side 35 is inclined upward from the upstream side toward the downstream side as described above. Even if the recording paper ST is curled, the recording paper ST is discharged along the inclined side 35.
[0043]
In the double-sided printing mode, if the recording sheet ST printed on one side passes through the transport path R and then the cover member 191 is opened, the recording sheet ST can be discharged face up on the cover member 191. . In addition to the cover member 191, a discharge receiving member that can be opened and closed can be provided inside the cover member 191.
[0044]
【The invention's effect】
As described above, according to the present invention, the path defining portion of the duplex printing unit protrudes from one side surface of the image forming apparatus, and is disposed on the path defining portion so as to be rotatable around a predetermined fulcrum shaft. The printer is equipped with a paper discharge receiving member that defines the double-sided printing conveyance path when the printer is in the open state and intercepts the double-sided printing conveyance path in the middle when it is open and receives the recording paper that has passed through the fixing unit in a face-up state. Therefore, even when the double-sided printing unit is mounted on the image forming apparatus, the recording paper can be discharged face-up with a very simple configuration.
[0045]
In the present invention, the double-sided conveyance path is positioned on the fixing unit side and extends substantially horizontally, on the downstream side of the horizontal portion, the arc-shaped portion extending in an arc shape, and on the downstream side of the arc-shaped portion. And a vertical portion extending in a substantially vertical direction, the discharge receiving member is provided corresponding to the horizontal portion and the arc-shaped portion, and the fulcrum shaft is provided corresponding to the lower end of the arc-shaped portion. There is an effect that the recording sheet sent from the fixing unit can be received by the discharge receiving member only by opening the discharge receiving member without requiring another mechanism.
[0046]
In the present invention, the paper discharge receiving member constitutes a part of the exterior of the duplex printing unit main body, defines a duplex printing conveyance path, and a rib portion that is formed on the inner surface of the cover and extends along the duplex printing conveyance path When the paper discharge receiving member is closed, the lower end of the rib portion is located below the fulcrum shaft. The double-sided printing conveyance path is interrupted in the middle of the printing paper, so that the recording paper is not inserted into the paper reversing part side.
[0047]
In the present invention, since the discharge receiving member is closed, the lower end portion of the rib portion is provided with an inclined portion that is inclined outward toward the downstream side. At this time, the inclined portion is inclined upward from the fixing unit side toward the downstream side, so that the recording paper can be discharged smoothly.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing an image forming apparatus equipped with an example of a duplex printing unit according to the present invention.
FIG. 2 is a cross-sectional view showing a part of the duplex printing unit shown in FIG. 1 in a state in which a paper discharge receiving member (cover member) is closed.
3 is a perspective view showing a part of the duplex printing unit shown in FIG. 1 in a state in which a paper discharge receiving member (cover member) is opened. FIG.
4 is a cross-sectional view showing an example of a state where a part of the duplex printing unit shown in FIG.
FIG. 5 is a cross-sectional view showing another example of a state in which a discharge receiving member (cover member) is opened for a part of the duplex printing unit shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Image forming apparatus main body 11 Photosensitive drum 16 Paper feed cassette 17 Transfer roller 18 Fixing unit (fixing roller pair)
19 Duplex printing unit (paper reversing unit)
191 Discharge receiving member (cover member)
21 Path switching member 32 Path defining member (conveying rib member)
33 rib 34 fulcrum shaft 35 inclined side

Claims (6)

The image forming apparatus includes an image forming unit that forms an image on a recording sheet, and a fixing unit that is disposed on the downstream side of the image forming unit and fixes the recording sheet on which the image is formed by the image forming unit. A double-sided printing unit that is disposed in the image forming apparatus, receives a recording sheet having an image formed on one side through the fixing unit, inverts the surface of the recording sheet, and sends the recording sheet to the image forming unit. And
A recording paper reversing unit that inverts the recording paper and sends it to the image forming unit;
A path defining unit that is positioned between the fixing unit and the recording sheet reversing unit and that defines a duplex printing conveyance path for feeding the recording sheet conveyed from the fixing unit to the recording sheet reversing unit;
The path defining portion protrudes from one side surface of the image forming apparatus,
The path defining portion is disposed so as to be rotatable around a predetermined fulcrum shaft, defines the duplex printing conveyance path when closed, and interrupts the duplex printing conveyance path when opened. And a sheet receiving member for receiving the recording sheet that has passed through the fixing unit in a face-up state. The duplex printing unit according to claim 1, wherein the duplex printing unit is detachable from the image forming apparatus. The double-sided printing conveyance path is positioned on the fixing unit side and extends substantially horizontally,
An arcuate portion located on the downstream side of the horizontal portion and extending in an arcuate shape;
A vertical portion located on the downstream side of the arc-shaped portion and extending in a substantially vertical direction,
3. The sheet discharge receiving member is provided corresponding to the horizontal portion and the arc-shaped portion, and the fulcrum shaft is provided corresponding to a lower end of the arc-shaped portion. The duplex printing unit as described. The paper discharge receiving member constitutes a part of a double-sided printing unit main body exterior, and a cover that defines the double-sided printing conveyance path;
A rib portion formed on the inner surface of the cover and extending along the double-sided printing path;
When the paper discharge receiving member is closed, the lower end of the rib portion is located below the fulcrum shaft,
4. The duplex printing unit according to claim 3, wherein when the sheet receiving member is in an open state, the duplex printing conveyance path is blocked in the middle at the lower end of the rib portion. An inclined portion that is inclined outward toward the downstream side is defined at the lower end portion of the rib portion in a state in which the paper discharge receiving member is closed,
5. The double-sided printing according to claim 4, wherein when the sheet receiving member is in an open state, the inclined portion is inclined upward from the fixing unit side toward the downstream side. unit. Detecting means for detecting that the paper discharge receiving member is in an open state and sending a cover open signal;
The image forming apparatus includes a paper discharge path connected to the fixing unit, a paper discharge tray for receiving the recording paper face down through the paper discharge path, and the fixing unit for the duplex printing conveyance path or the paper discharge. A path switching member selectively connected to the path; and a control unit that controls the path switching member in response to the cover opening signal to connect the fixing unit and the duplex printing conveyance path. The double-sided printing unit according to any one of claims 1 to 5.

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