JP2004323216A - Double-side printing unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform face-up delivery of paper by simple structure when a double-side printing unit is installed on an image forming device. <P>SOLUTION: This double-side printing unit 19 comprises a recording paper reversal part reversing recording paper and feeding the recording paper to an image forming part and a route specifying part 19a in which a double-side printing carrying route R positioned between a fixing unit 18 and the recording paper reversal part and feeding the recording paper carried from the fixing unit to the recording paper reversal part is specified. The route specifying part is projected from one side face of the image forming device 10, and a delivery paper receiving member 191 disposed rotatably about a specified pivot shaft, specifying the double-side printing carrying route in a closed state, and receiving the recording paper passed through the fixing unit in a face-up state by interrupting the double-side printing carrying route midway in the closed state is installed in the route specifying part. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile using an electrophotographic process, and more particularly, to a duplex printing unit used in an image forming apparatus.
[0002]
In general, as an image forming apparatus, an image forming section forms an image (printing) on one side (first side) of a recording sheet, and then reverses the image-formed recording sheet on the first side and re-images the image. 2. Description of the Related Art An image forming apparatus that conveys a recording sheet to form an image on the other side (second surface) of a recording sheet and forms an image on both sides of the recording sheet is known.
[0003]
In order to support double-sided printing, the image forming apparatus is provided with a double-sided printing unit, and in a double-sided printing mode, a recording sheet on which an image has been formed on one side is sent to the double-sided printing unit. Then, the recording paper is sent to the image forming section again 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 is a so-called face-up discharge in which the paper is discharged, and a so-called face-down discharge in which the print surface is discharged to the discharge tray with the print surface facing down. Similarly, in the case of duplex printing, the second surface is directed upward. When the recording paper is discharged to the discharge tray, the face-up discharge is performed, and when the recording paper is discharged with the second surface facing down, the face-down discharge is performed.
[0005]
In face-up discharge and face-down discharge, the page order of the recording paper discharged to the discharge tray is reversed. For this reason, in recent years, an image forming apparatus has been known in which a user can select face-up discharge or face-down discharge as necessary.
[0006]
For example, the recording paper that has passed through the fixing unit is discharged face-down to a discharge tray provided at the top of the image forming apparatus main body via a 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 mounted on the image forming apparatus as described above, the face-up tray may not be used in some cases. In order to prevent such a problem, there has been known an image forming apparatus in which a double-sided printing unit can be easily mounted on an image forming apparatus main body and face-up discharge can be performed.
[0008]
Here, when performing double-sided image formation, the face-up tray is closed at a substantially vertical position. Thus, the relay tray is pushed up by the cam member 58, and the recording sheet is transported 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 to a position near 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 drawing, which is substantially parallel to the face-up tray (see Patent Document 1).
[0009]
[Patent Document 1]
JP-A-8-188344 (paragraphs (0060) to (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. In the face-up state, the sheet is discharged to the face-up tray via the relay tray.However, the relay tray needs to be linked with the opening / closing operation of the face-up tray. There is a problem that an interlocking mechanism including a cam member and the like is required, and the configuration becomes extremely complicated.
[0011]
Further, the image forming apparatus described in Patent Document 1 has a problem that a relay tray is required and the number of components increases.
[0012]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a double-sided printing unit capable of performing 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, the image forming apparatus includes: 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 in conjunction with an image forming apparatus, disposed on the image forming apparatus, receives a recording sheet on which an image has been formed on one side after passing through the fixing unit, reverses the side of the recording sheet, and sends it to the image forming section. A double-sided printing unit, comprising: a recording sheet reversing unit for reversing the recording sheet and sending it to the image forming unit; and a recording sheet conveyed from the fixing unit positioned between the fixing unit and the recording sheet reversing unit. A path defining unit that defines a double-sided printing conveyance path for feeding a sheet to the recording sheet reversing unit; the path defining unit protrudes from one side of the image forming apparatus; Is disposed so as to be rotatable about a fulcrum axis, and defines the double-sided printing transport path when in the closed state, and cuts off the double-sided printing transport path halfway through the fixing unit when in the open state. A double-sided printing unit is provided, which is provided with a paper discharge receiving member for receiving recording paper in a face-up state.
[0014]
In this way, the path defining portion of the duplex printing unit protrudes from one side of the image forming apparatus, and is disposed on the route defining portion so as to be rotatable around a predetermined fulcrum axis. If a double-sided printing conveyance path is interrupted in the middle of the opening state and a sheet receiving member for receiving the recording sheet passing through the fixing unit in a face-up state when the opening state is provided, the two-sided printing unit can Even when the recording paper is mounted on the forming apparatus, the recording paper can be discharged face-up with a very simple configuration.
[0015]
In the present invention, the double-sided printing unit is detachable from the image forming apparatus, and the double-sided conveyance path is located on the fixing unit side and extends substantially horizontally, and is located on the downstream side of the horizontal portion. An arc-shaped portion extending in an arc shape, and a vertical portion located on the downstream side of the arc-shaped portion and extending in a substantially vertical direction, wherein the paper discharge receiving member corresponds to the horizontal portion and the arc-shaped portion. The fulcrum shaft is provided corresponding to a lower end of the arc-shaped portion.
[0016]
As described above, the two-sided conveyance path is located on the fixing unit side and extends substantially horizontally, the arc portion is located downstream of the horizontal portion and extends in an arc, and is located on the downstream side of the arc portion. And a vertical portion extending substantially in the vertical direction, the paper 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. By simply opening the paper discharge receiving member, the recording paper sent from the fixing unit can be received by the paper discharge receiving member without requiring any other mechanism.
[0017]
Further, in the present invention, the discharge receiving member constitutes a part of the exterior of the duplex printing unit main body, and a cover that defines the duplex printing transport path, and is formed on an inner surface of the cover, and the duplex printing transport path is formed. And a lower end of the rib portion is located below the fulcrum shaft when the paper discharge receiving member is closed, and the paper discharge receiving member is in an open state. At this time, the double-sided printing conveyance path is interrupted at the lower end of the rib portion.
[0018]
As described above, the paper discharge receiving member forms a part of the exterior of the duplex printing unit main body, and defines the cover that defines the duplex printing transport path, and the rib that is formed on the inner surface of the cover and extends along the duplex printing transport path. Since the lower end of the rib portion is located below the fulcrum shaft when the discharge receiving member is closed, when the discharge receiving member is opened, the lower end of the rib portion is closed. Since the double-sided printing conveyance path is interrupted halfway, the recording paper is not inserted into the paper reversing section.
[0019]
When the discharge receiving member is closed, an inclined portion which is inclined outward toward the downstream side is defined at a lower end portion of the rib portion, and when the discharge receiving member is opened, The inclined portion is inclined upward from the fixing unit toward the downstream side.
[0020]
In this way, if the inclined portion that inclines outward toward the downstream side is defined at the lower end of the rib portion in a state where the sheet receiving member is closed, when the sheet receiving member is opened, The inclined portion is inclined upward from the fixing unit side toward the downstream side, so that the recording paper can be smoothly discharged.
[0021]
Further, in the present invention, the duplex printing unit is provided with a detecting means for detecting that the paper discharge receiving member is in an open state and transmitting a cover open signal, while the image forming apparatus has 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 a path switching for selectively connecting the fixing unit to the double-sided printing conveyance path or the paper discharge path. And a control means for controlling the path switching member in response to the cover opening signal to connect the fixing unit to the double-sided printing conveyance path.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention thereto, unless otherwise specified. It is only an example.
[0023]
First, referring to FIG. 1, the illustrated image forming apparatus is an image forming apparatus using an electrophotographic process, and the image forming apparatus includes a photosensitive drum 11 as a latent image carrier, a developing device, a charging device, An exposure unit and a cleaning unit (a developing unit, a charger, an exposure unit, and a cleaning unit are not shown) are provided. After the photosensitive drum 11 is charged by the charger, the exposure unit responds to image data. The photosensitive drum 11 is exposed to light, 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 be a toner image.
[0024]
A paper cassette 16 containing recording paper is detachably mounted on the image forming apparatus main body 10, and the paper cassette 16 is located on the front side (the right side in FIG. 1: one side) of the image forming apparatus main body 10. It is attached so that it can be pulled out. One of the recording sheets stacked in the sheet cassette 16 is picked up by a pickup roller 16a, and reaches a registration roller pair 16d through a sheet conveyance path P by a feed roller pair 16b and a conveyance roller 16c. It is sent to the nip between the transfer roller 11 and the transfer roller 17. Then, the toner image on the photosensitive drum 11 is transferred onto the recording paper to form a transfer image.
[0025]
Thereafter, the recording paper is sent to the fixing unit (pair of fixing rollers) 18 through the paper transport path P, where the transfer image on the recording paper is fixed. Then, the residual toner remaining on the photosensitive drum 11 is removed by the cleaning unit. Note that an image forming unit is configured by the above-described photosensitive drum 11, a developing device, a charging device, a developing device, an exposure unit, a transfer roller, and the like.
[0026]
In the example shown in FIG. 1, a double-sided printing unit (sheet reversing unit) 19 is mounted below the sheet feeding cassette 16, and the sheet reversing unit 19 is attached to the image forming apparatus main body 10 on its rear side (sheet feeding cassette). 16 is detachable from the front side on which the image forming apparatus 16 is mounted, and is mounted on the image forming apparatus main body 10 as necessary (that is, the sheet reversing unit 19 is optionally provided later). 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 described later.
[0027]
In the illustrated example, one end (the left end in the figure) of the sheet reversing unit 19 is mounted on the image forming apparatus main body 10 and protrudes from the rear side of the image forming apparatus main body 10. A conveyance path (double-sided printing conveyance path) R through which the sheet is conveyed is defined in the protruding portion, and a sheet reversing roller 19b is accommodated below the conveyance path R (hereinafter, this protruding portion is simply referred to as a path defining portion). I will). A paper discharge receiving member (cover member) 191 constituting a part of the exterior of the duplex printing unit is provided on the upper side of the path defining portion 19a. When the cover member 191 is opened as described later, The cover member 191 is used as a face-up tray. 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 print mode is selected on the operation panel 10a provided in the image forming apparatus main body with the cover member 191 closed, the path switching member 21 located at the subsequent stage of the fixing unit 18 discharges the upper surface 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 two-sided print mode is selected on the operation panel 10a with the cover member 191 closed, the path switching member 21 is set to the two-sided print mode position, and the recording paper sent from the fixing unit 18 travels along the transport path R. Then, the sheet is conveyed into the sheet reversing unit 19.
[0030]
When the recording sheet is conveyed to the conveyance path R, the recording sheet is detected by a reversing sheet detection sensor (not shown), and the control device (not shown) rotates the sheet reversing roller 19b in the direction shown by the solid line arrow. Control. As a result, the recording sheet is transported along the path indicated by the solid arrow, and reaches the 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 dashed arrow. As a result, the recording sheet is sent from the reversing path S in the direction indicated by the dashed arrow, is conveyed by the conveying roller 19e through a path (hereinafter referred to as a reversing path) T, reaches the above-described sheet conveying path P, and Reaches 16d.
[0032]
A paper detection sensor (not shown) is disposed in the reversing path T. When a paper is detected by the paper detection sensor, the photosensitive drum 11 is driven to rotate, and charging and exposure are performed 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 sheet on which double-sided printing has been performed is discharged to the discharge tray 10b formed on the upper surface of the image forming apparatus main body through the discharge path Q by the path switching member 21 returning to the upper discharge tray 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. And the above-described path switching member 21 is disposed.
[0034]
Referring also to FIG. 3, the above-described transport path R is defined by a cover member 191 and a path defining member (transport rib member) 32 facing the cover member 191, and the path defining member 32 extends in a substantially vertical direction. It has an extending vertical plane (vertical plane) 32a, an arc-shaped surface 32b, and a horizontal plane 32c extending in a substantially horizontal direction, and one end (the right end in FIG. 2) of the horizontal plane 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 protruding in a direction perpendicular to the inner surface on the inner 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 arc-shaped surface 32b corresponding to the above-described arc-shaped surface 32b, and has one end (the lower end in FIG. 2) with respect to the fulcrum shaft 34 provided in the path defining portion 19a. It is rotatable.
[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 inclined from the lowest point toward the upstream side of the transport path R. Is formed. That is, the inclined side 35 inclined in the direction approaching the path defining member 32 from the lowest point 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 inclined outward toward the downstream side is defined).
[0037]
Then, as described later, when the cover member 191 is rotated about the fulcrum shaft 34 and the cover member 191 is opened, the transport path R is blocked by the lower end of the rib 33.
[0038]
As shown in FIG. 3, hook portions 191a are formed at both end portions of the cover member 191. When the cover member 191 is closed, the cover member 191 is held by the route defining portion 19a by the hook portions 191a. Will be done.
[0039]
Here, referring to FIG. 3 and FIG. 4, when the user wants to perform face-up discharge in one-sided printing, the user selects the one-sided printing mode using the mode operation panel, and the user attaches the cover member 191. When the cover member 191 is opened by rotating about 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 open signal indicating that the cover is open is provided to the control device from a cover open / close detection sensor (not shown). When the control device receives the cover open 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 sheet 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 sheet is not sent to the sheet discharge path Q but is sent to the transport path R. Then, since the cover member 191 is in the opened state, the recording sheet ST is discharged face-up to the inner side surface of the cover member 191 from the middle of the transport path R.
[0041]
When the recording paper is ejected to the cover member 191, the lower end of the rib 33 blocks the transport path R, and the inclined side 35 is formed at the lower end of the rib 33 as described above. When the cover member 191 is opened, as shown in FIG. 3, the inclined side 35 is inclined upward from the upstream side to the downstream side, and the recording paper ST is smoothly faced to the cover member 191. You can eject paper 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 transport path R is blocked by the lower end of the rib 33. Since the recording sheet ST does not enter the reversing path S and the inclined side 35 is inclined upward from the upstream side to the downstream side as described above, The recording paper ST is discharged along the inclined side 35 even if the recording paper ST is curled.
[0043]
In the double-side printing mode, if the cover member 191 is opened after the recording sheet ST printed on one side passes through the transport path R, the recording sheet ST can be discharged face-up on the cover member 191. . Further, a configuration in which an openable / closable paper discharge receiving member is provided inside the cover member 191 separately from the cover member 191 may be adopted.
[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 of the image forming apparatus, and is disposed on the path defining portion so as to be rotatable around a predetermined fulcrum axis. A double-sided printing conveyance path is defined in the state, and a sheet receiving member for receiving the recording sheet passing through the fixing unit in a face-up state by shutting off the double-sided printing conveyance path in the middle when the state is opened is provided. Therefore, even when the duplex printing unit is mounted on the image forming apparatus, the recording paper can be discharged face-up with a very simple configuration.
[0045]
According to the present invention, the two-sided conveyance path includes a horizontal portion that is located on the fixing unit side and extends substantially horizontally, an arc-shaped portion that is located downstream of the horizontal portion and that extends in an arc shape, and that is located downstream of the arc-shaped portion. And a vertical portion extending in a substantially vertical direction, and the paper ejection 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 sheet discharge receiving member only by opening the sheet 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 main body of the duplex printing unit, a cover defining the duplex printing transport path, and a rib portion formed on the inner surface of the cover and extending along the duplex printing transport path. Since the lower end of the rib portion is located below the fulcrum shaft when the discharge receiving member is closed, when the discharge receiving member is opened, the lower end of the rib portion is closed. Since the double-sided printing conveyance path is interrupted halfway, the recording paper is not inserted into the paper reversing section.
[0047]
In the present invention, since the inclined portion that is inclined outward toward the downstream side is defined at the lower end portion of the rib portion in a state where the sheet receiving member is closed, the sheet receiving member is opened. In this case, the inclined portion is inclined upward from the fixing unit side toward the downstream side, and there is an effect that the recording paper can be smoothly discharged.
[Brief description of the drawings]
FIG. 1 is a view schematically showing an image forming apparatus to which an example of a duplex printing unit according to the present invention is attached.
FIG. 2 is a cross-sectional view showing a part of the duplex printing unit shown in FIG. 1 in a state where a sheet discharge receiving member (cover member) is closed.
FIG. 3 is a perspective view showing a part of the duplex printing unit shown in FIG. 1 in a state where a sheet discharge receiving member (cover member) is opened.
FIG. 4 is a cross-sectional view illustrating an example of a state in which a sheet receiving member (cover member) is opened for a part of the duplex printing unit illustrated in FIG.
FIG. 5 is a cross-sectional view illustrating another example of a state in which a discharge receiving member (cover member) is opened for a part of the duplex printing unit illustrated in FIG. 1;
[Explanation of symbols]
Reference Signs List 10 Image forming apparatus main body 11 Photoconductor drum 16 Paper feed cassette 17 Transfer roller 18 Fixing unit (fixing roller pair)
19 Double-sided printing unit (paper reversing unit)
191 Paper receiving member (cover member)
21 path switching member 32 path defining member (transport rib member)
33 rib 34 fulcrum shaft 35 inclined side

Claims (6)

Used together with an image forming apparatus that includes 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. A double-sided printing unit disposed in the image forming apparatus, receiving a recording sheet on which an image is formed on one surface side after passing through the fixing unit, inverting the surface of the recording sheet, and sending the recording sheet to the image forming unit; hand,
A recording paper reversing unit for reversing the recording paper and sending it to the image forming unit,
A path defining unit is provided between the fixing unit and the recording sheet reversing unit, the path defining unit defining a double-sided printing conveyance path for sending the recording sheet transported from the fixing unit to the recording sheet reversing unit.
The path defining unit protrudes from one side of the image forming apparatus,
The path defining section is disposed so as to be rotatable around a predetermined fulcrum axis, defines the double-sided printing transport path in a closed state, and shuts off the double-sided printing transport path in the middle of the opening state. A double-sided printing unit, further comprising a sheet receiving member for receiving the recording sheet passing 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, a horizontal portion located on the fixing unit side and extending substantially horizontally,
An arc-shaped portion located downstream of the horizontal portion and extending in an arc shape;
A vertical portion that is located on the downstream side of the arc-shaped portion and extends in a substantially vertical direction,
The paper 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. Double-sided printing unit as described. The discharge receiving member constitutes a part of the exterior of the duplex printing unit main body, and a cover that defines the duplex printing transport path;
A rib portion formed on the inner surface of the cover and extending along the double-sided printing path;
When the paper receiving member is closed, the lower end of the rib portion is located below the fulcrum shaft,
4. The double-sided printing unit according to claim 3, wherein the double-sided printing conveyance path is interrupted at the lower end of the rib portion when the discharge receiving member is opened. At the lower end portion of the rib portion in a state where the sheet receiving member is closed, an inclined portion inclined outward toward the downstream side is defined.
5. The double-sided printing according to claim 4, wherein when the discharge receiving member is opened, the inclined portion is inclined upward from the fixing unit side toward the downstream side. 6. unit. Detecting means for detecting that the sheet receiving member is in an open state and transmitting a cover open signal is provided,
The image forming apparatus includes a paper discharge path connected to the fixing unit, a paper discharge tray that receives the recording sheet face down through the paper discharge path, A path switching member selectively connected to the path, and control means for controlling the path switching member in response to the cover opening signal to connect the fixing unit to the double-sided printing conveyance path. The double-sided printing unit according to claim 1.

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