JP2005289541A - Optional discharge device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable selection of the number of discharge trays according to user's need. <P>SOLUTION: The optional discharge device (U6) is equipped with an upper attaching/detaching part (1a) which is installed on an upper end part of the optional discharge device (U6) and detachably constituted relative to a lower attaching/detaching part (19) of the other optional discharge device (U6) disposed on the upper part, the lower attaching/detaching part (19) which is installed on a lower end part of the optional discharge device (U6) and detachably constituted relative to the upper attaching/detaching part (1a) of the other optional discharge device (U6) disposed on the lower part, a common carrying path (64) where the sheet carried from the other optional discharge device (U6) disposed on the lower part is carried, optional discharge paths (61, 62) where the sheet discharged to a discharge tray (TRh2) is carried, and an upper carrying path (63) where the sheet carried to the other optional discharge device (U6) disposed on the upper part is carried. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a fax machine, a printer, and a copying machine, and an optional discharge device added to the image forming apparatus for discharging a sheet on which an image is recorded, and in particular, configured to be detachable from the image forming apparatus main body The present invention relates to an optional discharge device and an image forming apparatus to which the optional discharge device is attached and detached.

  In a conventional image forming apparatus, a sheet discharge member (discharge roller or the like) that discharges a sheet on which an image is recorded to a discharge tray is provided in the image forming apparatus main body. In addition to the sheet discharge member provided in the main body, an image forming apparatus including an optional discharge device such as a sorter device or a mailbox sorter device that sorts and discharges the discharged sheets is disclosed in the following prior art ( J01) and (J02) are known.

(J01) Technology described in Patent Document 1 (Japanese Patent Laid-Open No. 7-315668) Patent Document 1 describes a face-down paper discharge tray (16) that is discharged in a state where the image recording surface is the bottom surface, and an image recording surface. In addition to the face-up discharge tray (18) discharged in the upper surface state, a sorter having a plurality of trays (47a) above the image forming apparatus main body or above each discharge tray (16 or 18) ( 40) is provided.

(J02) Technology described in Patent Document 2 (Japanese Patent Laid-Open No. 9-301602) In Patent Document 2, a mail box (12) having four trays (30a to 30d) is mounted above the main body of the image forming apparatus. An image forming apparatus is described. Patent Document 2 describes an image forming apparatus in which a one-bin device (121) having one sheet discharge tray (125) is installed above a sheet discharge member of an image forming apparatus main body.

JP-A-7-315668 ("0013" to "0015", "0021" to "0025", FIGS. 1, 4, and 5) JP-A-9-301602 ("0014" to "0018", "0034" to "0035", FIGS. 1 and 19)

In the prior arts (J01) and (J02), a predetermined number of trays are provided in optional discharge devices such as a sorter (40), a mail box (12), and a 1-bin device (121). Accordingly, when the optional discharge device is installed in the image forming apparatus main body, the number of trays required by the user is determined in advance, and the required number of trays, discharge members (discharge rollers) for each tray, It is necessary to prepare an optional discharge device including a switching device for switching trays to be discharged.
However, if the number of trays required by the user fluctuates after installation of the optional discharge tray, it is necessary to remove the installed optional discharge tray and prepare an optional discharge tray according to the number of trays after the change. There is a problem that the number of trays cannot be changed flexibly according to the user's needs. In addition, since the entire optional discharge device is replaced, there is a problem that the burden on the user in terms of cost and the burden of replacement work increase.

  In addition, in anticipation of an increase in the number of necessary trays, if an optional discharge device with an excessive number of trays is installed, the entire image forming apparatus becomes unnecessarily large due to unnecessary trays and discharge members. There is a problem. Further, when the number of necessary trays is reduced and the optional discharge device is not replaced, there is a problem that the entire image forming apparatus is unnecessarily large due to unnecessary trays and the like.

In view of the above-described circumstances, the present invention has the following description contents (O01) and (O02) as technical problems.
(O01) The number of discharge trays can be selected according to the user's needs.
(O02) To prevent the entire image forming apparatus from becoming larger than necessary.

(Invention)
Next, the present invention that has solved the above problems will be described. In order to facilitate the correspondence between the elements of the present invention and elements of specific examples (examples) of the embodiments described later, Add the code enclosed in parentheses. The reason why the present invention is described in correspondence with the reference numerals of the embodiments described later is to facilitate understanding of the present invention, and not to limit the scope of the present invention to the embodiments.

(First invention)
In order to solve the technical problem, the optional discharge device of the first invention is characterized by comprising the following structural requirements (A01) to (A06).
(A01) A lower detachable portion (19; 16, 18, 19) of another optional discharge device (U6; U6 ') provided at the upper end of the optional discharge device (U6; U6') and disposed above. Upper detachable part (1a; 1a, U11 ′, U16 ′ to U19 ′) configured to be detachable with respect to
(A02) Upper attachment / detachment portion (1a; 1a, U11 ′, U16 ′) of another option discharge device (U6; U6 ′) provided at the lower end of the option discharge device (U6; U6 ′) and disposed below To U19 ′), a lower detachable part (19; 16, 18, 19) configured to be detachable.
(A03) A common conveyance path (64) through which a sheet conveyed from another optional discharge device (U6; U6 ′) arranged below is conveyed,
(A04) An optional discharge path (61, 62) connected to the common transport path (64) and transported to a discharge tray (TRh1, TRh1 ′, TRh2; TRh2, TRh4 to TRh6);
(A05) An upper conveyance path (63) that is connected to the common conveyance path (64) and conveys a sheet to be conveyed to another optional discharge device (U6; U6 ′) disposed above.
(A06) A tray that is disposed at a connection portion of the common conveyance path (64), the optional discharge path (61, 62), and the upper conveyance path (63), and conveys the sheet to the optional discharge path (61, 62). A conveyance path switching gate (54) movable between a discharge position and an upper conveyance position for conveying a sheet to the upper conveyance path (63).

(Operation of the first invention)
In the optional discharge device (U6; U6 ′) according to the first aspect of the present invention having the structural requirements (A01) to (A06), the upper attachment / detachment portion (1a; provided at the upper end of the optional discharge device (U6; U6 ′)). 1a, U11 ′, U16 ′ to U19 ′) are attached to and detached from the lower attachment / detachment portion (19; 16, 18, 19) of another optional discharge device (U6; U6 ′) disposed above. The lower attachment / detachment portion (19; 16, 18, 19) provided at the lower end of the option discharge device (U6; U6 ′) is an upper attachment / detachment portion of another option discharge device (U6; U6 ′) disposed below. It is attached to and detached from (1a; 1a, U11 ′, U16 ′ to U19 ′). A common conveyance path (64) conveyed from another optional discharge device (U6; U6 ′) disposed below and a sheet discharged to the discharge trays (TRh1, TRh1 ′, TRh2; TRh2, TRh4 to TRh6) are conveyed. The connection path between the option discharge path (61, 62) and the upper transfer path (63) where the sheet to be transferred to another option discharge device (U 6; U 6 ′) disposed above is conveyed A switching gate (54) is arranged. The tray switching gate (54) can move between a tray discharge position for conveying the sheet to the optional discharge path (61, 62) and an upper conveyance position for conveying the sheet to the upper conveyance path (63). .

  Therefore, in the option discharge device (U6; U6 ′) of the first invention, another option discharge device (U6; U6 ′) can be attached and detached below and above the option discharge device (U6; U6 ′). As a result, the optional discharge devices (U6; U6 ′) can be mounted as many as the number of discharge trays (TRh1, TRh1 ′, TRh2; TRh2, TRh4 to TRh6) according to the user's needs, which the user needs. Even if the number of trays varies, the optional discharge device (U6; U6 ′) and the discharge trays (TRh1, TRh1 ′, TRh2; TRh2, TRh4 to TRh6) can be easily varied. Therefore, the number of optional discharge devices (U6; U6 ′) and discharge trays (TRh1, TRh1 ′, TRh2; TRh2, TRh4 to TRh6) can be increased / decreased as required by the user.

  In addition, it is possible to adapt to the number of optional discharge devices (U6; U6 ′) and discharge trays (TRh1, TRh1 ′, TRh2; TRh2, TRh4 to TRh6) according to the needs of the user, so unnecessary optional discharge devices. (U6; U6 ′) and discharge trays (TRh1, TRh1 ′, TRh2; TRh2, TRh4 to TRh6) can prevent the whole from becoming unnecessarily large. Since the number of optional discharge devices (U6; U6 ′) and discharge trays (TRh1, TRh1 ′, TRh2; TRh2, TRh4 to TRh6) can be adjusted according to the needs of the user, an excessive number of discharge devices and trays are necessary. Therefore, it is possible to make a cost burden and a work burden according to the required number of users, and it is possible to suppress an unnecessary burden. Further, since the optional discharge device (U6; U6 ′) can be attached / detached, the attachment / detachment operation can be easily performed even if the number required by the user increases or decreases.

(First Embodiment 1)
An optional discharge device (U6; U6 ′) according to the first aspect of the present invention is characterized in that in the first aspect of the present invention, the following structural requirements (A07) and (A08) are provided.
(A07) a face-down conveyance path (61) for conveying the sheet to face-down trays (TRh1, TRh1 ′; TRh4 to TRh6) from which the sheet is discharged in a face-down state where the image recording surface on which the image is recorded is the bottom surface; ,
A face-up conveyance path (62) for conveying the sheet to a face-up tray (TRh2) from which the sheet is discharged in a face-up state in which the image recording surface is an upper surface;
The optional discharge path (61, 62),
(A08) A face-up discharge position as the tray discharge position for discharging sheets to the face-up tray (TRh2), and a tray discharge position for discharging sheets to the face-down trays (TRh1, TRh1 ′; TRh4 to TRh6) The transfer path switching gate (54) that can move between the face-down discharge position and the upper discharge position.

(Operation of Form 1 of the First Invention)
In the optional discharge device (U6; U6 ′) according to the first aspect of the first invention having the above-described structural requirements (A07) and (A08), the optional discharge path (61, 62) is a face-down tray (TRh1, TRh1 ′; A face-down conveyance path (61) for conveying the sheet to TRh4 to TRh6) and a face-up conveyance path (62) for conveying the sheet to the face-up tray (TRh2). The tray switching gate (54) includes a face-up discharge position for discharging sheets to the face-up tray (TRh2), and a face-down for discharging sheets to the face-down trays (TRh1, TRh1 ′; TRh4 to TRh6). It is possible to move between the discharge position and the upper transport position. Therefore, the optional discharge device (U6; U6 ′) according to the first aspect of the first invention can discharge the sheet in the face-up state or the face-down state. Therefore, the number of optional discharge devices (U6; U6 ′), face-up trays (TRh2) and face-down trays (TRh1, TRh1 ′; TRh4 to TRh6) can be changed according to the user's needs.

(Second invention)
In order to solve the technical problem, the image forming apparatus of the second invention is characterized by comprising the following structural requirements (B01) to (B03).
(B01) A main body discharge tray (TRh) that is provided in the image forming apparatus main body (U1) and discharges a sheet on which an image is recorded,
(B02) a main body discharge member (R1) for discharging the sheet to the main body discharge tray (TRh),
(B03) A lower detachable portion (19; 16, 18, 19) of another optional discharge device (U6; U6 ') provided at the upper end of the optional discharge device (U6; U6') and disposed above. An upper detachable portion (1a; 1a, U11 ′, U16 ′ to U19 ′) configured to be detachable from the device;
Another optional discharge device (U6; U6 ') provided at the lower end of the optional discharge device (U6; U6') or the upper attachment / detachment portion (1a, U12) of the image forming apparatus main body (U1). 1a, U11 ', U16'-U19'), a lower detachable part (19; 16, 18, 19) configured to be detachable;
A common conveyance path (64) through which a sheet conveyed from another optional discharge device (U6; U6 ′) or an image forming apparatus main body (U1) disposed below is conveyed;
An optional discharge path (61, 62) connected to the common transport path (64) and transporting sheets discharged to the discharge trays (TRh1, TRh1 ′, TRh2; TRh2, TRh4 to TRh6);
An upper conveyance path (63) that is connected to the common conveyance path (64) and that conveys a sheet conveyed to another optional discharge device (U6; U6 ′) disposed above;
A tray discharge position that is disposed at a connection portion of the common conveyance path (64), the optional discharge path (61, 62), and the upper conveyance path (63), and conveys the sheet to the optional discharge path (61, 62); An optional discharge device (U6; U6 ') having a conveyance path switching gate (54) movable between an upper conveyance position for conveying the sheet to the upper conveyance path (63).

(Operation of the second invention)
In the image forming apparatus according to the second aspect of the present invention having the structural requirements (B01) to (B03), the main body discharge tray (TRh) provided in the main body (U1) of the image is imaged by the main body discharge member (R1). The sheet on which is recorded is discharged. The upper attachment / detachment portion (1a; 1a, U11 ′, U16 ′ to U19 ′) provided at the upper end of the option discharge device (U6; U6 ′) is connected to another option discharge device (U6; U6 ′) disposed above. ) Is attached to and detached from the lower attaching / detaching portion (19; 16, 18, 19). The lower attachment / detachment portion (19; 16, 18, 19) provided at the lower end of the optional discharge device (U6; U6 ′) is another optional discharge device (U6; U6 ′) or an image forming apparatus disposed below. The main body (U1) is attached to and detached from the upper attaching / detaching portions (1a, U12; 1a, U11 ′, U16 ′ to U19 ′). A common conveyance path (64) conveyed from another optional discharge device (U6; U6 ′) disposed below and a sheet discharged to the discharge trays (TRh1, TRh1 ′, TRh2; TRh2, TRh4 to TRh6) are conveyed. The connection path between the option discharge path (61, 62) and the upper transfer path (63) where the sheet to be transferred to another option discharge device (U 6; U 6 ′) disposed above is conveyed A switching gate (54) is arranged. The conveyance path switching gate (54) moves between a tray discharge position for conveying the sheet to the optional discharge path (61, 62) and an upper conveyance position for conveying the sheet to the upper conveyance path (63). it can.

  Therefore, in the image forming apparatus of the second invention, another optional discharge device (U6; U6 ′) can be attached and detached below and above the optional discharge device (U6; U6 ′). As a result, the optional discharge devices (U6; U6 ′) can be mounted as many as the number of discharge trays (TRh1, TRh1 ′, TRh2; TRh2, TRh4 to TRh6) according to the user's needs, which the user needs. Even if the number of trays varies, the optional discharge device (U6; U6 ′) and the discharge trays (TRh1, TRh1 ′, TRh2; TRh2, TRh4 to TRh6) can be easily varied. Therefore, the number of optional discharge devices (U6; U6 ′) and discharge trays (TRh1, TRh1 ′, TRh2; TRh2, TRh4 to TRh6) can be selected according to the needs of the user.

  In addition, it is possible to adapt to the number of optional discharge devices (U6; U6 ′) and discharge trays (TRh1, TRh1 ′, TRh2; TRh2, TRh4 to TRh6) according to the needs of the user, so unnecessary optional discharge devices. (U6; U6 ′) and discharge trays (TRh1, TRh1 ′, TRh2; TRh2, TRh4 to TRh6) can prevent the whole from becoming unnecessarily large. Since the number of optional discharge devices (U6; U6 ′) and discharge trays (TRh1, TRh1 ′, TRh2; TRh2, TRh4 to TRh6) can be adjusted according to the needs of the user, more discharge devices and trays than necessary. Therefore, it is possible to make a cost burden and a work burden according to the required number of users, and it is possible to suppress an unnecessary burden. Further, since the optional discharge device (U6; U6 ′) can be attached and detached, the attachment and detachment work can be easily performed even if the number required by the user increases or decreases.

The above-described present invention has the following effects (E01) to (E02).
(E01) The number of discharge trays can be selected as required by the user.
(E02) It is possible to prevent the entire image forming apparatus from becoming larger than necessary.

Next, specific examples (examples) of the embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples.
In order to facilitate understanding of the following description, in the drawings, the front-rear direction is the X-axis direction, the left-right direction is the Y-axis direction, the up-down direction is the Z-axis direction, and arrows X, -X, Y, -Y, The direction indicated by Z and -Z or the indicated side is defined as the front side, the rear side, the right side, the left side, the upper side, the lower side, or the front side, the rear side, the right side, the left side, the upper side, and the lower side, respectively.
In the figure, “•” in “○” means an arrow heading from the back of the page to the front, and “×” in “○” is the front of the page. It means an arrow pointing from the back to the back.

1 is a perspective explanatory view of an image forming apparatus according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram of the image forming apparatus according to the first embodiment.
1 and 2, a digital copying machine U as an image forming apparatus according to the first embodiment includes an image forming apparatus main body U1 and an automatic document feeder U2. A sheet reversing device U3 is detachably mounted on the upper left side surface of the image forming apparatus main body U1.
The image forming apparatus main body U1 includes an IOT (image output terminal) and an IIT (image input terminal, that is, an image reading unit).
The automatic document feeder U2 is supported on the platen glass PG on the top surface of the IIT.
A sheet discharge tray (main body discharge tray) TRh is provided between the upper surface of the IOT and the upper IIT.

3A and 3B are perspective explanatory views for explaining a state in which the optional discharge unit is attached to the image forming apparatus of the present invention, FIG. 3A is an overall perspective explanatory view, and FIG. 3B is an enlarged explanatory view of a main part indicated by an arrow IIIB in FIG. FIG. 3C is an enlarged explanatory view of the main part viewed from the direction of arrow IIIC in FIG. 3A.
In FIG. 1, a lower top cover U1a is detachably attached to the left upper end portion of the sheet discharge tray TRh with respect to the image forming apparatus main body U1, and the upper top cover U1a is located above the lower top cover. 'Is detachably attached to the image forming apparatus main body U1. In FIG. 3, a left side cover U1b is rotatably supported on the left side of the image forming apparatus main body U1. The top covers U1a and U1a ′ are removed when an optional discharge unit (U6) described later is mounted.

  In FIG. 3, when the top covers U1a and U1a ′ are removed, the main body connector U11 (see FIG. 3A) and the upper left portion of the IOT are exposed. On the exposed upper portion of the IOT, unit right support frames (upper detachable portions) U12 and U12 extending in the front-rear direction are provided at intervals in the vertical direction. In FIG. 3B, a rear bracket U13 is formed at the rear end of each unit right support frame U12. In FIG. 3C, a front bracket U14 protruding rearward is formed at the front end of the unit right support frame U12. The brackets U13 and U14 are formed with discharge unit positioning holes U16 and U17. The front and rear frames support discharge unit lock pins U18 and U19 that protrude inward.

1 and 2, the automatic document feeder U2 has a document feed tray TG1 on which a plurality of documents Gi to be copied are stacked. Each of the plurality of documents Gi placed on the document feed tray TG1 is sequentially passed through a copy position on the platen glass PG and discharged to the document discharge tray TG2. The automatic document feeder U2 is rotatable with respect to the upper surface of the platen glass PG by a hinge shaft (not shown) provided in the rear end portion (−X end portion) extending in the left-right direction. When a person puts it on the platen glass PG by hand, it is rotated upward.
The image forming apparatus main body U1 has a UI (user interface) through which a user inputs an operation command signal such as a copy start.

In FIG. 2, an exposure optical system A for reading a document image is disposed below the transparent platen glass PG.
Reflected light from a document conveyed on the upper surface of the platen glass PG by the automatic document feeder U2 or a document (not shown) manually placed on the platen glass PG is passed through the exposure optical system A to a CCD ( It is converted into an electrical signal by a solid-state imaging device).
An IPS (image processing system) converts an electrical signal input from a CCD into image data and temporarily stores it, and outputs the image data to a laser drive circuit DL as image data for forming a latent image at a predetermined timing. To do.
The laser drive circuit DL outputs a laser drive signal to the ROS (latent image forming apparatus) according to the input image data. The operation of the UI (user interface), IPS and laser drive signal output device DL, and a power supply circuit E for applying a bias voltage to the developing roll Ga and transfer roll Rt described later are controlled by a controller C.

In FIG. 2, a toner image forming device Up for forming a black toner image is disposed on the left side of the ROS. A laser beam L emitted from the laser diode (not shown) of the latent image forming optical system ROS enters the rotating photoconductor PR.
In FIG. 2, the toner image forming apparatus Up includes an image carrier PR constituted by a photosensitive drum rotating in an arrow direction (see FIG. 2), a charging roll (charging member) CR, a developing device G, and a cleaner. CL. The toner image forming apparatus Up is unitized, and is configured to be detachable from the image forming apparatus main body U1 as a process unit Up. The process unit (toner image forming apparatus) Up is attached and detached with the front cover U1c (see FIG. 1) supported on the front surface of the image forming apparatus main body U1 being openable and closable.

The surface of the image carrier PR is uniformly charged by a charging roll CR, and then exposed and scanned by a laser beam L of the ROS (latent image forming apparatus) at a latent image writing position to form an electrostatic latent image. Is done.
The surface of the image carrier PR on which the electrostatic latent image is formed rotates and moves sequentially through a developing area (area facing the developing roll) and a transfer area (area facing the transfer roll) Q3.
The developing device G includes a developing roll Ga to which a developing bias is applied, developer stirring members Gb, Gc, and Gd that transport the developer to the developing roll Ga while stirring the developer, and the developing roll Ga and the developer stirring members Gb to Gd. And a developing container V for rotatably supporting the developer. Then, the electrostatic latent image on the image carrier PR passing through the developing area is developed into a toner image by the developing roll Ga.

A plurality of paper feed trays TR1 to TR4 (see FIGS. 1 and 2) for storing recording sheets to be conveyed to the transfer area Q3 are arranged in the front-rear direction (the direction perpendicular to the paper surface in FIG. 2) on both the left and right sides. It is supported so as to be movable along a pair of rails RL1 and RL1 arranged along the rails.
The recording sheets taken out from the paper feed trays TR1 to TR4 by the pick-up roll Rp are separated one by one by a separating roll Rs having a retard roll and a paper feed roll, and arranged along the sheet conveyance path SH. The sheet is conveyed by a plurality of sheet conveying rolls Ra and conveyed to the transfer area Q3 by a registration roll Rr at a predetermined timing.
The recording sheet S fed from the manual feed tray TR0 is also transported to the transfer region Q3 by the sheet transport roll Ra and the registration roll Rr arranged along the sheet transport path SH.
A sheet conveying device (SH + Ra + Rr) is configured by the sheet conveying path SH, the sheet conveying roll Ra, the registration roll Rr, and the like.

A transfer roll (transfer device) Rt to which a transfer bias is applied is disposed in the transfer region Q3. The transfer roll Rt is in pressure contact with the image carrier PR in the transfer area Q3. When the recording sheet passes through the transfer area Q3, the transfer roll Rt is supplied to the transfer roll Rt from a power supply circuit E controlled by the controller C. At this timing, a transfer bias (transfer voltage) is applied. At this time, the toner image on the image carrier PR is transferred to the recording sheet by the transfer roll Rt.
After the toner image on the surface of the image carrier PR is transferred to the recording sheet in the transfer region Q3, the toner remaining on the surface of the image carrier PR is collected by the cleaner CL (see FIG. 2). The image carrier PR from which the residual toner adhering to the surface is collected by the cleaner CL is charged again by the charging roll CR.

In FIG. 2, the recording sheet on which the unfixed toner image is transferred in the transfer area Q3 is conveyed to the fixing device F disposed above the transfer roll Rt with the toner image being unfixed.
In FIG. 2, the fixing device F has a pair of fixing members Fh and Fp configured by a heating roll (heating fixing member) Fh and a pressure roll (pressing fixing member) Fp rotating in pressure contact with each other. ing. The fixing device F is unitized, and is configured to be detachable from the image forming apparatus body U1 as the fixing unit F.
The recording sheet S on which the unfixed toner image is transferred is conveyed to a fixing region Q4 formed by a pressure contact region between the heating roll Fh and the pressure roll Fp, and the toner image is fixed by the heating roll Fh and the pressure roll Fp. Is done.

  In FIG. 2, the recording sheet on which the fixing toner image is formed is guided by the right sheet guide SG1, the left sheet guide SG2, and the discharge device switching gate (discharge switching gate) GT1, and is conveyed to the main body discharge roll (main body discharge member) R1. Then, it is discharged to the sheet discharge tray TRh by the main body discharge roll R1. The left sheet guide SG2 is rotatably supported by the case of the fixing device F. Further, the discharge device switching gate GT1 controls a discharge device switching gate motor (stepping motor or the like) (not shown) to discharge a sheet to the main body discharge tray TRh, and a sheet reversing device during duplex printing. It moves between a reversing device conveyance position for guiding the sheet to U3 and an optional discharge position for conveying the sheet to an optional discharge unit U6 described later. Note that the discharge device switching gate GT1 can be moved between the three positions by using a plurality of solenoids and springs (for example, see Japanese Patent Application Laid-Open No. 7-315668) without using a motor.

  A reversing path transporting roll R2 that transports the sheet to the sheet reversing device U3 during duplex printing is disposed on the left side of the paper discharge roll R1. In the image forming apparatus U illustrated in FIG. 2, when performing image recording on both sides of a recording sheet, when the trailing edge of the recording sheet that has been recorded on one side (recorded on the first side) is conveyed to the paper discharge roll R <b> 1, The paper discharge roll R1 rotates reversely and is switched back. And it is guided by the upper surface of left sheet guide SG2, and is conveyed by the said reverse path conveyance roll R2. The sheet conveyed to the reversing path conveying roll R2 passes through the sheet reversing path SH1 formed inside the sheet reversing apparatus U3, and is retransmitted to the transfer area Q3 in a state where the front and back are reversed. Is recorded.

FIG. 4 is an explanatory diagram of an image forming apparatus equipped with a sheet post-processing apparatus and an optional discharge unit.
In FIG. 4, the image forming apparatus U <b> 1 according to the first exemplary embodiment includes a finisher (sheet post-processing apparatus) U <b> 4 that performs post-processing of a sheet and a finisher conveyance apparatus that conveys the sheet discharged from the discharge roll R <b> 1 to the finisher U <b> 4. A post-processing sheet conveying device (U5) can be additionally mounted. Further, two optional discharge units (optional discharge devices) U6 can be additionally mounted on the image forming apparatus U1 of the first embodiment.
The finisher U4 includes a top tray U4a that discharges the sheet conveyed to the finisher U4 as it is, an end binding device U4b that binds the ends of the sheet bundle after aligning the plurality of sheets, and a sheet bundle after aligning the plurality of sheets. And a saddle stitching device U4c that binds the central portion of each. Since such a finisher (post-processing device) U4 is conventionally known (see, for example, JP-A-2003-89463), detailed description thereof is omitted.

The finisher transfer device U5 includes a lower main body U5a and an upper main body U5b supported by the lower main body U5a. The lower surface U5c of the lower main body U5a is supported on the upper surface of the main body discharge tray TRh. A plurality of lower finisher transport rollers R3a are rotatably supported on the upper surface of the lower main body U5a.
On the lower surface of the upper body U5b, an upper finisher transport roller R3b is rotatably supported corresponding to the lower finisher transport roller R3a. Accordingly, a finisher conveyance path SH2 is formed between the lower main body U5a and the upper main body U5b, and the sheet conveyed to the finisher conveyance path SH2 by the main body discharge roller R1 is finished by the pair of upper and lower finisher conveyance rollers R3a and R3b. Transported to U4.

Further, on the upper surface of the upper main body U5b, a lower option face-down tray (option) on which sheets discharged from the option discharge unit U6 disposed below among the two option discharge units U6 mounted are placed. A discharge tray (discharge tray) TRh1 is formed. The optional face-down tray TRh1 according to the first exemplary embodiment discharges a sheet in a face-down state in which the image recording surface of the sheet is the lower surface.
The image forming apparatus U according to the first embodiment has the finisher U4. However, when the finisher U4 is not attached and an option discharge unit to be described later is attached, the image forming apparatus U has only the option face-down tray TRh1 and has the finisher. It is also possible to detachably mount an optional discharge tray unit in which the transport rollers R3a and R3b and the finisher transport path SH2 are omitted.

  In FIG. 4, above the option face-down tray TRh1, there is an upper option face-down tray (option discharge tray, discharge tray) TRh1 ′ on which a sheet discharged from the option discharge unit U6 disposed above is placed. Is provided. The upper option face-down tray TRh1 ′ is attached to the rear frame of the image forming apparatus main body U1.

FIG. 5 is a perspective explanatory view seen from the face-down tray side of the optional discharge unit to which the face-up tray is attached.
6A and 6B are perspective explanatory views as seen from the face-up tray side of the optional discharge unit, FIG. 6A is a perspective explanatory view when the face-up tray is not mounted, and FIG. 6B is a perspective explanatory view when the face-up tray is mounted. It is.
FIG. 7 is a front end view of the optional discharge unit.
FIG. 8 is a rear end view of the optional discharge unit.

9A and 9B are cross-sectional explanatory views of main parts of the optional discharge unit, FIG. 9A is a cross-sectional explanatory view of main parts when the face-up tray is not mounted, and FIG. 9B is a cross-sectional description of main parts when the face-up tray is mounted. FIG.
FIG. 10 is an explanatory perspective view of the optional discharge unit with the upper end portion opened.
FIG. 11 is a front end view of the optional discharge unit with its upper end opened, and corresponds to FIG.
FIG. 12 is a rear end view of the option discharge unit with the upper end opened, and corresponds to FIG.
FIG. 13 is a rear end view of the option discharge unit with the option face-up tray rotated upward, and corresponds to FIG.

5-12, the optional discharge unit U6 attached to the image forming apparatus main body U1 includes a right face-down case 1, a left face-up case 2, a front cover 3, and a rear cover 4. have. The lower end portion of the face-down side case 1 and the lower end portion of the face-up side case 2 are connected by a pair of front and rear hinge shafts 6 and 6 (see FIGS. 7 and 8). Therefore, the upper end portion of the face-down side case 1 and the upper end portion of the face-up side case 2 are between the case closed state shown in FIGS. 5 to 9 and the case open state shown in FIGS. It is comprised so that opening and closing is mutually possible. In the option discharge unit U6 according to the first exemplary embodiment, when the upper ends of the cases 1 and 2 are opened with the option discharge unit U6 attached to the image forming apparatus main body U1, the face-down side case 1 has the image. It becomes a fixed part supported by the forming apparatus main body U1, and becomes a rotating part in which the face-up side case 2 rotates with respect to the face-down side case 1.
The front cover 3 and the rear cover 4 are detachably attached to the front and rear ends of the face-down side case 1.

(Description of face down side case 1)
In FIG. 5, a unit support surface 1 a that supports a supported surface (described later) of an optional discharge unit U <b> 6 mounted on the upper side is provided on the upper surface of the face-down case 1. A face-down discharge port 11 is formed on the right end surface (+ Y-side end surface) of the face-down side case 1. A full detection sensor 12 is arranged above the center portion in the front-rear direction of the face-down discharge port 11. The full detection sensor 12 is a conventionally known sensor that detects whether or not the optional face down tray TRh1 is fully loaded by the sheet bundle discharged and stacked on the optional face down tray TRh1. Further, an option side connector 13 that protrudes to the right is provided at the rear portion (−X side portion) of the face down side case 1.

  7, 8, 11, and 12, the front and rear end surfaces of the left lower end portion (−Y side −Z end portion) of the face-down side case 1 can be rotated around the hinge shaft 6. A lock member 16 is supported. The mounting lock member 16 includes a mounting contact inclined surface 16a formed at the right end (+ Y end) and a mounting pin engagement provided on the left side (−Y side) of the mounting contact inclined surface 16a. It has a joint part 16b and an unlocking operation part 16c. The mounting lock member 16 is normally held in the state shown in FIGS. 7 and 8 by a torsion spring (not shown).

7, 8, 11, and 12, on the right side of the mounting lock member 16, pin support portions 17, 17 are integrally formed on the face-down side case 1, and the pin support portion 17. , 17 are fixedly supported by mounting positioning pins 18 and 18 that protrude to the right (+ Y side).
Further, when the image forming apparatus main body U1 is mounted, the upper right surface of the image forming apparatus main body U1, the unit right support frame U12, or an optional discharge unit U6 mounted below is mounted on the lower right side of the face-down side case 1. A supported surface (lower attachment / detachment portion) 19 supported by the upper unit support surface 1a and the like is formed.

7 and 11, a plate support arm (angle holding member support arm) 20 is supported above the hinge shaft 6 of the face-down side case 1 so as to be rotatable about an arm rotation shaft 20a.
8, 12, and 13, a sensor support member 21 is supported on the rear end surface of the face-down side case 1. A sensor support bent portion 21a bent in the rear is integrally formed at the upper left end (−Y side end portion) of the sensor support member 21, and the sensor support bent portion 21a includes: A tray detection sensor SN1 is supported. The tray detection sensor SN1 includes a sensor main body 22 and a tray detection bar 23 that can project and be accommodated with respect to the sensor main body 22.

  5 and 9, the face-down discharge port 11 has a face-down discharge roller (an optional discharge member, which includes a drive roller 26 that rotates and a corrugation roller 27 that contacts and faces the drive roller 26. A face-down discharge member) 28 is disposed. The drive roller 26 is driven to rotate forward when discharging the sheet to the optional face-down tray TRh1, and is driven to rotate backward when conveying the sheet to the sheet reversing device U3 side during duplex printing. The corrugation roller 27 is a conventionally known roller (for example, Japanese Patent Laid-Open No. Hei 8-208091) that curls the sheet and applies a strain to the sheet in order to improve the straightness of the sheet discharged to the optional face-down tray TRh1. Therefore, detailed description is omitted. Further, the face-down discharge roller 28 according to the first embodiment has an offset discharge function for shifting (offset) the sheets discharged to the option face-down tray TRh1 in the width direction. The configuration for discharging the offset is well known in the art (see, for example, Japanese Patent Application Laid-Open No. Hei 8-208098), and thus detailed description thereof is omitted.

  9 and 10, a plurality of face-down seat guides 31 are integrally supported on the left portion (−Y side portion) of the face-down side case 1. In FIG. 9, a common conveyance path driven roller 32 is disposed below the face-down sheet guide 31. A right common conveyance path sheet guide 33 is supported by the face-down side case 1 below the common conveyance path driven roller 32. The common conveyance path driven roller 32 is driven to rotate forward when the sheet is conveyed upward (+ Z direction), and is driven to rotate reversely when the sheet is conveyed downward (−Z direction).

(Description of face-up side case 2)
5 and 6, an additional unit accommodating portion cover 2a is detachably attached to the upper end surface of the face-up side case 2. 5 to 8, a case opening operation unit 41 is provided at the front upper end of the face-up side case 2. 11 and 12, a case locking member 42 having a locking claw 42a is connected to the case opening operation portion 41, and the case locking member 42 is normally fitted with a locking member (not shown). It is latched by the joint hole and is held in the case closed state shown in FIGS. When the user operates the case opening operation portion 41, the case locking member 42 rotates and the engagement with the locking member fitting hole (not shown) is released. At this time, the face-up side case 2 rotates about the hinge shaft 6 with respect to the face-down side case 1, and the upper end portion of the face-up side case 2 is opened with respect to the upper end portion of the face-down side case 1. The

  In FIG. 6, when the optional face-up tray (optional discharge tray, discharge tray) TRh2 (see FIG. 6B) is not attached to the optional discharge unit U6, the discharge port sealing cover 42 is provided on the left end surface (−Y end surface). Is installed. In FIG. 6B, when the optional face-up tray TRh2 is attached to the optional discharge unit U6, the discharge port sealing cover 42 is removed. When the discharge port sealing cover 42 is removed, the face-up discharge port 43 formed on the left end surface of the face-up side case 2 is exposed.

  7 and 11, a tray support plate (face-up tray support member) 46 is supported at the front end portion of the face-up side case 2. A front tray support shaft (face-up tray support member) 47 is fixedly supported on the tray support plate 46. An optional face-up tray (optional discharge tray) TRh2 is mounted on the tray support shaft 47, and a lower left portion of a tray angle holding plate (mounting surface angle holding member) 48 is rotatably supported. The upper right portion of the tray angle holding plate 48 is rotatably supported by the plate support arm 20 that is rotatably supported by the face-down side case 1. A tray locking surface 48a (see FIGS. 7 and 11) is formed at the lower portion of the tray angle holding plate 48, and a gate position holding engagement portion is provided at the upper right edge of the tray angle holding plate 48. 48b is formed.

Therefore, even when the face-up side case 2 is opened and closed with respect to the face-down side case 1, the tray angle holding plate 48 is brought into a predetermined posture by the tray support plate 46 and the plate support arm 20 before and after opening and closing. Retained.
The tray support plate 46, the front tray support shaft 47, the tray angle holding plate 48, the plate support arm 20 and the like constitute a mounting surface angle holding link mechanism L.
8 and 12, a rear tray support shaft (face-up tray support member) 49 is fixedly supported at the rear end portion of the face-up side case 2.

  In FIG. 6B and FIG. 9, the face-up discharge port 43 is rotatably supported by a face-up discharge roller (option discharge member, face-up discharge member) 51 having a driving roller and a driven roller. 9 and 10, a plurality of face-up sheet guides 52 are integrally supported by the face-up side case 2 at the lower right of the face-up discharge roller 51. A tray switching gate (conveying path switching gate) 54 is rotatably supported on the upper right side of the face-up sheet guide 52. The tray switching gate 54 has a face-down gate portion 56 disposed on the face-down discharge port 11 side and a face-up gate portion 57 disposed on the face-up discharge port 43 side.

  In FIG. 10, a plurality of face-down gate portions 56 and face-up gate portions 57 are arranged side by side in the front-rear direction, and face-down gate portions 56 adjacent to each other in the front-rear direction, or face-up gate portions. 57 are connected to each other by a connecting portion 54a. The face-down gate portion 56 and the face-up gate portion 57 are connected at both front and rear ends, and are rotatably supported by the face-up side case 2. Accordingly, the plurality of gate portions 56 and 57 are configured to be integrally rotatable around the rotation centers 56a and 57a.

In FIG. 9, a face down guide surface 56b is formed on the right side surface (+ Y side surface) of the face down gate portion 56, and a right upper transport guide surface 56c is formed on the left side surface. Further, a face-up guide surface 57b is formed on the left side surface (−Y side surface) of the face-up gate portion 57, and a left upper conveyance guide surface 57c is formed on the right side surface.
Further, in FIGS. 7, 10, and 11, an opening engagement portion 54c that protrudes further forward is integrally formed at the front end portion of the face-down gate 56.

  Two solenoids and springs (not shown) are connected to the tray switching gate 54, and sheets are discharged to the face-down tray TRh1 by on / off control of two solenoids (face-up solenoid and face-down solenoid). A face-down discharge position (tray discharge position, position shown in FIG. 9A), a face-up discharge position (tray discharge position, position shown in FIG. 9B) for discharging a sheet to the face-up tray TRh2, and an option arranged above It is configured to be movable between an upper conveyance position for conveying the sheet to the discharge unit U6 (a position indicated by the tray switching gate 54 of the optional discharge unit U6 mounted below in FIG. 4). The configuration for rotating the tray switching gate 54 with a solenoid or the like is conventionally known (for example, see Japanese Patent Application Laid-Open No. 7-315668), and thus detailed description thereof is omitted.

In FIGS. 9 and 10, below the face-up sheet guide 52, a common path conveyance path driving roller 58 that faces and contacts the common conveyance path driven roller 32 is supported by the face-up side case 2. Yes. A left common conveyance path sheet guide 59 is supported by the face-up side case 2 below the common path conveyance path driving roller 58. The common conveyance path driven roller 32 and the common conveyance path drive roller 58 constitute a common conveyance path sheet conveyance roller 60.
In FIG. 9, above the tray switching gate 54, an additional unit accommodating portion 2b in which the common conveying path sheet conveying roller 60 and the common conveying path sheet guides 33 and 59 of the optional discharge unit U6 disposed above are accommodated. Is provided. The upper part of the additional unit accommodating portion 2b is closed by the additional unit accommodating portion cover 2a.

  In FIG. 9, when the tray switching gate 54 is moved to the face-down discharge position (position shown in FIG. 9A), a face-down conveyance path (optional discharge) is provided between the face-down guide surface 56b and the face-down sheet guide 31. Road) 61 is formed. When the tray switching gate 54 is moved to the face-up discharge position (position shown in FIG. 9B), a face-up conveyance path (optional discharge path) is provided between the face-up guide surface 57b and the face-up sheet guide 52. 62 is formed. Further, in a state where the tray switching gate 54 is moved to the upper conveyance position (the position indicated by the tray switching gate 54 of the optional discharge unit U6 mounted below in FIG. 4), the right upper conveyance guide surface 56c and the left upper conveyance guide. An upper conveyance path 63 is formed between the surface 57c. A common conveyance path 64 is formed between the lower part of the face-down sheet guide 31 and the lower part of the face-up sheet guide 52 and between the common conveyance path sheet guides 33 and 59.

  Therefore, when the tray switching gate 54 moves to the face-down discharge position (see FIG. 9A), the sheet conveyed upward through the common conveyance path 64 by the common conveyance path sheet conveyance roller 60 is conveyed to the face-down conveyance path 61. And discharged to the option face down tray TRh1. Further, when the tray switching gate 54 moves to the face-up discharge position (see FIG. 9B), the sheet conveyed upward through the common conveyance path 64 by the common conveyance path sheet conveyance roller 60 is conveyed to the face-up conveyance path 62. , And discharged to the optional face-up tray TRh2. Further, when the tray switching gate 54 is moved to the upper conveyance position (see FIG. 4), the sheet conveyed upward on the common conveyance path 64 by the common conveyance path sheet conveyance roller 60 is conveyed to the upper conveyance path 63, and The sheet is conveyed to the optional discharge unit U6 disposed in the position.

  In FIG. 7, the optional discharge unit U <b> 6 according to the first embodiment is configured so that the opening engagement portion 54 c is in a state where the face-down side case 1 and the face-up side case 2 are closed (the state shown in FIG. 7). Is configured not to contact the plate support arm 20, the tray switching gate 54 is movable between a face-down discharge position and a face-up discharge position. On the other hand, in FIGS. 10 and 11, when the upper end portion of the face-up side case 2 is opened with respect to the upper end portion of the face-down side case 1 (the state shown in FIGS. 10 and 11), The joining portion 54 c engages with the gate position holding engagement portion 48 b of the tray angle holding plate 48. In this state, the tray switching gate 54 is configured to be held at the face-up discharge position (position shown in FIG. 9B).

(Explanation of optional face-up tray TRh2)
7, 8, and 10 to 12, the optional face-up tray TRh <b> 2 includes a face-up tray main body 71 having a sheet placement surface 71 a on which the sheet discharged from the face-up discharge port 43 is placed on the upper surface. Have. A substantially arc-shaped front supported portion (supporting member engaging portion) 72 and a rear supported portion (supporting member engaging portion) 73 are integrally formed at both front and rear ends of the face-up tray main body 71. The front supported portion 72 and the rear supported portion 73 are rotatably supported by the front tray support shaft 47 and the rear tray support shaft 49. Therefore, the option face-up tray TRh2 is detachably mounted with the tray support shafts 47 and 49 as the rotation center.

  7 and 11, a mounting surface angle setting unit 74 is formed integrally with the face-up tray main body 71 below the front supported portion 72. The front end portion (upper right end portion) of the mounting surface angle setting section 74 abuts on the tray locking surface 48a of the tray angle holding plate 48 when the option face-up tray TRh2 is mounted on the option discharge unit U6. And locked. Therefore, the sheet mounting surface 71a is held at a predetermined angle (see FIG. 7) inclined upward from the horizontal by the engagement between the mounting surface angle setting unit 74 and the tray locking surface 48a. When the face-up side case 2 is opened with respect to the face-down side case 1 (see FIG. 11), the tray angle holding plate 48 is held in a predetermined posture by the mounting surface angle holding link mechanism L described above. Therefore, the inclination angle (see FIG. 11) of the sheet placement surface 71a with respect to the horizontal hardly changes compared to before the face-up side case 2 is opened.

8, 12, and 13, a detection bar contact portion 73 a is formed at the upper right end edge (+ Y + Z side end edge) of the rear supported portion 73. And the detection bar non-contact part 73b is formed in the upper end edge of the rear side supported part 73 adjacent to the left (-Y direction) of the detection bar contact part 73a.
Therefore, when the face-up side case 2 is closed with respect to the face-down side case 1 (the state shown in FIG. 8), the tray detection bar 23 of the tray detection sensor SN1 comes into contact with the detection bar contact portion 73a. In this case, the tray detection bar 23 is accommodated in the sensor main body 22, the internal detection switch is turned on, and the tray detection sensor SN1 detects that the optional face-up tray TRh2 is mounted in a state where the sheet can be discharged. .

  On the other hand, the face-up side case 2 is opened with respect to the face-down side case 1 (state shown in FIG. 12), or the tip of the optional face-up tray TRh2 is turned upward (state shown in FIG. 13). Then, the tray detection bar 23 faces the detection bar non-contact portion 73b and does not come into contact therewith. Further, when the option face-up tray TRh2 is not mounted, there is no member with which the tray detection bar 23 comes into contact. In these cases, the tray detection sensor SN1 detects that the sheet cannot be discharged to the option face-up tray TRh2.

(Description of attachment / detachment of the optional discharge unit U6 to the image forming apparatus)
In FIG. 3, when the optional discharge unit U6 is mounted on the image forming apparatus main body U1, first, the front cover 3 and the rear cover 4 of the option discharge unit U6 are removed. Then, the first optional discharge unit U6 is brought close to the image forming apparatus main body U1 from which the lower top cover U1a has been removed, and the optional discharge unit lock pins U18 and U19 are brought into contact with the contact inclined surface 16a of the mounting lock member 16. The mounting positioning pins 18 and 18 are opposed to the optional discharge unit positioning holes U16 and U17, respectively. In this state, when the optional discharge unit U6 is pushed to the right (+ Y side), the optional discharge unit lock pins U18 and U19 are pushed in contact with the contact inclined surface 16a, so that the right end (+ Y) of the mounting lock member 16 is pushed. The end) rotates downward against the elastic force of the torsion spring. When pushed to the end, the mounting positioning pins 18 and 18 are fitted into the optional discharge unit positioning holes U16 and U17, and the optional discharge unit lock pins U18 and U19 are engaged with the mounting pin engaging portion 16b. Then, the mounting lock member 16 returns to the normal position by the force of the torsion spring.

  Accordingly, in this state, the optional discharge unit U6 is mounted on the image forming apparatus main body U1 while being positioned by the mounting positioning pins 18 and 18 and the optional discharge unit positioning holes U16 and U17, and the optional discharge is performed. The unit lock pins U18 and U19 and the pin engaging portion 16b at the time of mounting are locked so as not to move. The option side connector 13 and the main body side connector U11 are constituted by drawer connectors. When the option discharge unit U6 is attached to the image forming apparatus main body U1, the option side connector 13 is attached to the main body side connector U11. The Therefore, the option discharge unit U6 and the image forming apparatus main body U1 are electrically connected, and control signals, currents, and the like are transmitted from the image forming apparatus U1 via the connectors U11 and U13.

  When the second optional discharge unit U6 is mounted, the additional unit accommodating portion cover 2a of the optional discharge unit mounted below is removed, and the upper top cover U1a ′ is removed from the image forming apparatus main body U1. In the state where the common transport path sheet transport roller 60 and the common transport path sheet guides 33 and 59 of the second option discharge unit U6 are stored in the additional unit storage portion 2b of the first option discharge unit U6, As with the first optional discharge unit U6, it is pushed in from the side and attached.

(Description of the control part of Example 1)
FIG. 14 is a block diagram (functional block diagram) illustrating functions provided in the control unit of the image forming apparatus according to the first exemplary embodiment.
In FIG. 14, the controller C stores I / O (input / output interface) that performs input / output of signals to / from the outside and adjustment of input / output signal levels, programs and data for performing necessary processing, and the like. ROM (read-only memory), RAM (random access memory) for temporarily storing necessary data, CPU (central processing unit) that performs processing according to the program stored in the ROM, clock oscillator, etc. Various functions can be realized by executing a program stored in the ROM.

(Signal input element connected to the controller C)
The controller C receives the output signals of the next signal output elements UI and SN1.
UI: User interface The user interface UI includes a display unit UI1, a copy start key (copy start key) UI2, a copy number input key UI3, a numeric keypad UI4, a duplex printing designation key UI5, a discharge tray setting key UI6, a post-processing setting key UI7, and the like. It has.
SN1: Tray detection sensor The tray detection sensor SN1 detects whether or not the optional face-up tray TRh2 is mounted in a state where sheets can be discharged.

(Controlled element connected to controller C)
The controller C outputs a control signal for the next controlled element.
CG: Document Conveying Device Controller The document conveying device controller CG is a controller built in the automatic document conveying device U2, and operates the automatic document conveying device U2 according to a control signal output from the controller C of the image forming apparatus main body U1. Control.
CI: Image Scanner Controller The image scanner controller CI is a controller built in the image scanner (image reading unit, ie, IIT), and controls the operation of the IIT according to a control signal output from the controller C of the image forming apparatus body U1. To do.
CA: Post-processing device controller The post-processing controller CA is a controller built in the finisher (post-processing device) U4, and controls the operation of the finisher U4 according to a control signal output from the controller C of the image forming apparatus body U1. .

DL: Laser drive circuit The laser drive circuit DL drives a laser diode (not shown) of a ROS (latent image forming apparatus) to form an electrostatic latent image on the surface of the photoreceptor PR.
D1: Main Motor Drive Circuit The main motor drive circuit D1 drives the main motor M to rotationally drive the photoconductor PR and the developing roll Ga (see FIG. 2) of the developing device G through a gear (not shown).

E: Power supply circuit The power supply circuit E has the following power supply circuit.
E1: Power supply circuit for developing bias The power supply circuit for developing bias E1 applies a developing bias to the developing roll Ga of the developing device G.
E2: Charging power supply circuit The charging power supply circuit E2 applies a charging bias to the charging roll CR (see FIG. 2).
E3: Transfer Power Supply Circuit The transfer power supply circuit E3 applies a transfer bias to the transfer roll Rt (see FIG. 2).
E4: Power Supply Circuit for Fixing The power supply circuit for fixing E4 supplies heating power to the heating roll Fh.

D2: Sheet conveyance drive circuit The sheet conveyance drive circuit D2 drives the pickup roll Rp and the registration roll Rr via the clutches CL and CL by driving the sheet conveyance drive motor M3, and also supplies the sheet feed roll Rs and conveyance. The roll Ra, the reverse path transport roll R2, and the like are directly driven. Further, the sheet conveying drive circuit D2 drives the main body discharge roller R1 via the main body forward rotation clutch CL1 and the main body reverse rotation clutch CL2. When the main body forward rotation clutch CL1 is turned on and the main body reverse rotation clutch CL2 is turned off, the main body discharge roller R1 is driven to rotate forward (drive for discharging the sheet to the tray), and the main body forward rotation clutch CL1 is turned off. When the main body reverse rotation clutch CL2 is turned on, the main body discharge roller R1 performs reverse rotation driving (drive for conveying the sheet to the sheet reversing path SH1). Note that the main body discharge roller R1 can be configured to be driven to rotate forward and backward by using a sheet conveying drive motor that can rotate forward and backward without using the clutches CL1 and CL1.

D3: Tray switching solenoid drive circuit The tray switching solenoid drive circuit D3 includes two solenoids SL1 for the tray switching gate 54 in accordance with the designation of the discharge tray (TRh1, TRh1 ′, TRh2) from which the sheet is discharged. By controlling the on / off of SL2, the tray switching gate 54 is moved to the face-down discharge position (position shown in FIG. 9A), the face-up discharge position (position shown in FIG. 9B), and the upper transport position (lower position in FIG. 4). The position is moved between the positions indicated by the optional discharge unit U6. The tray switching solenoid drive circuit D3 according to the first embodiment turns off the two solenoids SL1 and SL2 in the normal state or when the upward conveyance position is set, and conveys the tray switching gate 54 upward by the elastic force of the spring. Hold in position. When discharge to the optional face-down tray TRh1 (or TRh1 ′) is designated, only the face-down solenoid SL1 is turned on, and the tray switching gate 54 is moved to the face-down position. When discharge to the optional face-up tray TRh2 is designated, the tray switching solenoid drive circuit D3 turns on only the face-up solenoid SL2 and moves the tray switching gate 54 to the face-up discharge position. .

D4: Discharge device switching motor drive circuit The discharge device switching motor drive circuit D4 controls the rotation angle of the motor for the discharge device switching gate GT1, thereby bringing the discharge device switching gate GT1 into the main body tray discharge position and the reversing device conveyance. Move between the position and the option discharge position.

D5: Option Discharge Unit Drive Circuit The option discharge unit drive circuit D5 drives the option discharge unit drive motor M4, thereby causing the face-down discharge roller 28 to pass through the option forward rotation clutch CL3 and the option reverse rotation clutch CL4. And the common conveyance path sheet conveyance roller 60 is driven, and the face-up discharge roller 51 is directly driven. When the optional forward rotation clutch CL3 is turned on and the optional reverse rotation clutch CL4 is turned off, the optional discharge roller (the face-down discharge roller 28 and the common conveyance path sheet conveyance roller 60) is driven to rotate in the positive direction. When CL3 is turned off and the optional reverse rotation clutch CL4 is turned on, the optional discharge rollers 28 and 60 are driven in reverse rotation. The optional discharge unit drive circuit D5, the optional discharge unit drive motor M4, the optional clutches CL3 and CL4, and the like are built in the optional discharge unit U6. The optional discharge rollers 28 and 60 can be driven to rotate forward and backward by using a sheet conveying drive motor that can rotate forward and backward without using the clutches CL3 and CL4.

(Function of the controller C)
The controller C has a program (function realization means) that realizes a function of executing a process according to an output signal from each signal output element and outputting a control signal to each control element. Next, a program (function realization means) for realizing various functions of the controller C will be described.
C1: Main motor rotation control means The main motor rotation control means C1 controls the main motor drive circuit D to control the rotation of the photoconductor PR, the developing roll Ga of the developing device G, the fixing device F, and the like.

C2: Power supply circuit control means The power supply circuit control means C2 includes the following means C2a to C2d, and controls the power supply circuit E to control the development bias, charging bias, transfer bias, and heater of the heating roll Fh. Control on-off etc.
C2a: Development Bias Control Unit The development bias control unit C2a controls the development bias applied to the development roll Ga of the developing unit G by controlling the operation of the development bias power supply circuit E1.
C2b: Charging Bias Control Unit The charging bias control unit C2b controls the operation of the charging bias power supply circuit E2 to control the charging bias applied to each charging roll CR.

C2c: Transfer Bias Control Unit The transfer bias control unit C2c controls the transfer bias applied to the transfer roll Rt by controlling the operation of the transfer power supply circuit E3.
C2d: Fixing power supply control means The fixing power supply control means C2d controls the operation of the fixing power supply circuit E4 to turn on and off the heater of the heating roll Fh.
C3: Latent image formation control means The latent image formation control means C3 controls the operation of the laser drive circuit DL to drive each laser diode (not shown) of the ROS (latent image forming apparatus), and to carry out the image carrier PR. An electrostatic latent image is formed on the surface.

C4: Option discharge unit mounting storage means The option discharge unit mounting storage means C4 stores whether or not the option discharge unit U6 is mounted on the image forming apparatus body U1. In the first embodiment, the mounting of the optional discharge unit U6 is configured to be stored by an input from the user interface UI. However, it is also possible to automatically detect and store the sensor by providing a sensor.
C5: Finisher transport device mounting storage means The finisher transport device mounting storage means C5 stores whether or not the finisher transport device U5 is mounted on the main body discharge tray TRh. In the first embodiment, the installation of the finisher transport device U5 is configured to be stored by input from the user interface UI. However, it is also possible to automatically detect and store the sensor by providing a sensor.

C6: Option face-up tray discharge possibility determination means The option face-up tray discharge possibility determination means C6 determines whether the sheet can be discharged to the option face-up tray TRh2 based on the detection signal from the tray detection sensor SN1. Remember. That is, when the tray detection sensor SN1 cannot detect the optional face-up tray TRh2 (when the sensor is off), the optional discharge tray TRh2 is not mounted or the leading end is pivoted upward, and the sheet is discharged. It is determined that the sheet cannot be discharged, and the prohibition of discharging the sheet to the option face-up tray TRh2 is stored. On the contrary, when the tray detection sensor SN1 detects the optional face-up tray TRh2, it is determined that the sheet can be discharged and stored.
C7: Double-sided printing designation storage unit The double-sided printing designation storage unit C7 determines whether single-sided printing or double-sided printing is designated according to a user input with the double-sided printing designation key UI5 of the user interface UI. Remember.

C8: Ejection tray designation storage means The ejection tray designation storage means C8 is a main body ejection tray TRh, optional face down trays TRh1, TRh1 ', and optional face up according to a user input with the ejection tray setting key UI6 of the user interface UI. Which of the trays TRh2 is designated is stored. When the finisher transport device U5 is mounted and the main body discharge tray TRh is designated, the sheet is transported to the finisher U4.
C9: Post-processing designation storage means The post-processing designation storage means C9 is designated to be ejected as it is to the top tray U4a according to the user input with the post-treatment setting key UI7 of the user interface UI, It stores whether the end binding for binding the end portion is designated or the saddle stitching for binding the center portion of the sheet is designated.

C10: Sheet Feed Control Unit The sheet feed control unit C10 includes a immediately preceding sheet conveyance determination unit C10A, a sheet conveyance determination unit C10B, a duplex printing sheet feedable position passage determination unit C10C, and an inter-sheet sheet feeding position. And a passage discriminating means C10D for controlling the sheet feeding timing by the pickup roll Rp.
C10A: Immediately preceding sheet conveyance determining means When the immediately preceding sheet conveyance determining means C10A feeds a sheet, whether or not the sheet (immediately preceding sheet) fed immediately before is being conveyed on the sheet conveying path (sheet path). Determine whether or not.

C10B: Pre-sheet conveyance determination means The pre-sheet conveyance determination means C10B determines whether or not a sheet fed before the immediately preceding sheet (pre-sheet) is being conveyed when feeding a sheet. Is determined.
C10C: Double-sided printing paper feedable position passage judging means The double-sided paper feeding position passage judging means C10C is a double-sided printing after the immediately preceding sheet that is switched back and conveyed to the sheet reversing device U3 at the front end of the fed sheet. It is determined whether or not the immediately preceding sheet has passed through a predetermined position that reaches after the end (a position capable of duplex printing and feeding). The double-sided sheet feeding position passage determining unit C10C according to the first exemplary embodiment performs determination based on the elapsed time from the start of feeding the immediately preceding sheet. It is also possible to determine.

C10D: Inter-sheet feedable position passage determining means The inter-sheet feedable position passage determining means C10D is a sheet to be fed when feeding a sheet between the preceding sheet and the immediately preceding sheet during duplex printing. It is determined whether or not the sheet has passed through a predetermined position (position where sheets can be fed between sheets) where the leading edge of the sheet reaches after the trailing edge of the preceding sheet. The inter-sheet feedable position passage determining unit C10D according to the first exemplary embodiment performs the determination based on the elapsed time from the start of sheet feeding before the sheet feeding. It is also possible to determine whether or not.
C11: Tray switching gate control means The tray switching gate control means C11 is a tray switching gate of each option discharge unit U6 according to the trays (option face down trays TRh1, TRh1 ′, option face up tray TRh2) designated by the user. 54 is moved to any one of a face-down discharge position, a face-up discharge position, and an upper conveyance position.

C12: Discharge Device Switching Gate Control Unit The discharge device switching gate control unit C12 includes a gate passage determination unit C12A and a first-side printed determination unit C12B. The discharge device switching gate GT1 is connected to the main body tray discharge position and the reversing device. Move to either the transport position or the optional discharge position.
C12A: Gate Passing Discriminating Unit The gate passing discriminating unit C12A discriminates whether or not the rear end in the sheet transport direction has passed through the discharge device switching gate GT1. The gate passage determination unit C12A according to the first exemplary embodiment makes a determination based on the elapsed time from the start of sheet feeding, but it is also possible to detect and determine whether or not a sheet sensor has been disposed.

C12B: First side printed discrimination means The first side printed discrimination means C12B prints the first side during duplex printing on the sheet that is next conveyed to the discharge device switching gate GT1, that is, the sheet that has passed through the fixing device F. Whether the second sheet is a printed sheet or not is discriminated 2.
C13: Option discharge roller rotation control means (option discharge member rotation control means)
The optional discharge roller rotation control means C13 controls the rotation of the optional discharge unit drive motor M4 to drive the optional discharge rollers (face-down discharge roller 28, face-up discharge roller 51, and common conveyance path sheet conveyance roller 60). Control.

(Description of Flowchart of Example 1)
(Description of main flowchart of sheet feeding process)
FIG. 15 is a main flowchart of the sheet feeding process of the image forming apparatus according to the first exemplary embodiment.
The processing of each ST (step) in the flowchart of FIG. 15 is performed according to a program stored in the ROM or hard disk of the controller C. This process is executed in a multitasking manner in parallel with other various processes of the image forming apparatus U.
The sheet feeding process flow shown in FIG. 15 is started when the image forming apparatus U is turned on.
In ST1 of FIG. 15, it is determined whether or not the job is started, that is, whether or not the copy start key UI2 is turned on. If no (N), ST1 is repeated, and if yes (Y), the process proceeds to ST2.

In ST2, it is determined whether or not single-sided printing is designated. If yes (Y), the process proceeds to ST3, and, if no (N), the process proceeds to ST4.
In ST3, a normal single-sided paper feed process is executed. That is, the sheets are sequentially fed in order to execute single-sided printing. Then, the process returns to ST1.
In ST4, it is determined whether or not the optional discharge unit U6 is attached. If no (N), the process moves to ST5, and if yes (Y), the process moves to ST6.
In ST5, a normal paper feed process for double-sided printing is executed. That is, a new sheet is fed each time the sheet immediately before being conveyed back to the sheet reversing device U3 by being switched back by the main body discharge roller R1 passes the set position where the duplex printing can be fed. Then, the process returns to ST1.

In ST6, it is determined whether or not the main body discharge tray TRh is designated. That is, when the finisher U4 and the finisher transport device U5 are mounted, it is determined whether or not transport to the finisher U4 is designated. If yes (Y) (when main body discharge tray TRh or finisher U4 is designated), the process proceeds to ST7, and if no (N), the process proceeds to ST8.
In ST7, sheet feeding processing when performing duplex printing using the optional discharge unit U6 and discharging it to the main body discharge tray TRh (the finisher U4 in the image forming apparatus U of Embodiment 1 in which the finisher U4 is mounted). When the main body discharge tray is designated, double-sided printing paper feed processing (see a subroutine of FIG. 16 described later) is executed. Then, the process returns to ST1.

  In ST8, for duplex printing when an optional discharge tray is designated, which is a paper feed process when discharging a sheet printed on both sides to an optional discharge tray (option face-down tray TRh1, TRh1 'or option face-up tray TRh2) specified by the user Execute paper feed processing. In other words, a new sheet is fed each time the sheet immediately before being switched back by the face-down ejection roller 28 of the optional ejection unit U6 and conveyed to the sheet reversing device U3 passes through the set double-sided printing paper feeding position. To do. Then, the process returns to ST1.

(Explanation of the flowchart of paper feed processing for duplex printing when the main body discharge tray is specified)
FIG. 16 is a flowchart of the double-sided printing paper feed process when the main body discharge tray is specified in the first embodiment, and is a flowchart of the subroutine of ST7 in FIG.
In ST11 of FIG. 16, it is determined whether there is image data for the first page. That is, it is determined whether or not a new sheet needs to be fed. If yes (Y), the process proceeds to ST12, and, if no (N), the process proceeds to ST17.

In ST12, it is determined whether or not the immediately preceding sheet is being conveyed on a sheet path (any one of the sheet conveyance path SH, the sheet reversing path SH1, the face-down conveyance path 61, and the common conveyance path 64). If yes (Y), the process proceeds to ST13, and, if no (N), the process proceeds to ST16.
In ST13, it is determined whether or not the sheet before the immediately preceding sheet, that is, the sheet before the sheet is being conveyed in the sheet path. If yes (Y), the process proceeds to ST14, and, if no (N), the process proceeds to ST15.
In ST14, it is determined whether or not the trailing edge position in the sheet conveyance direction of the preceding sheet has passed the inter-sheet feedable position. If yes (Y), the process proceeds to ST16, and, if no (N), ST14 is repeated.

In ST15, it is determined whether or not the rear end position of the immediately preceding sheet in the sheet conveyance direction has passed the double-sided printing paper feedable position. If yes (Y), the process proceeds to ST16, and, if no (N), ST15 is repeated.
In ST16, the pickup roll Rp is driven to feed a new sheet. Then, the process proceeds to ST17.
In ST17, it is determined whether or not the job is completed, that is, whether or not there is remaining image data. If no (N), the process moves to ST11, and if yes (Y), the subroutine of FIG. 16 is terminated and the process returns to the main routine of FIG.

(Description of main flowchart of discharge device switching gate switching process)
FIG. 17 is a main flowchart of the discharge device switching gate switching process of the image forming apparatus according to the first embodiment.
The processing of each ST (step) in the flowchart of FIG. 17 is performed according to a program stored in the ROM or hard disk of the controller C. This process is executed in a multitasking manner in parallel with other various processes of the image forming apparatus U.
The sheet feeding process flow shown in FIG. 17 is started when the image forming apparatus U is turned on.
In ST21 of FIG. 17, it is determined whether or not the job is started, that is, whether or not the copy start key UI2 is turned on. If no (N), ST21 is repeated, and if yes (Y), the process proceeds to ST22.

In ST22, it is determined whether or not single-sided printing is designated. If yes (Y), the process proceeds to ST23, and, if no (N), the process proceeds to ST28.
In ST23, it is determined whether or not the optional discharge unit U6 is attached. If yes (Y), the process proceeds to ST24, and, if no (N), the process proceeds to ST25.
In ST24, it is determined whether or not the main body discharge tray TRh is designated as a tray for discharging sheets (in the image forming apparatus U of the first embodiment, post-processing at the finisher U4 is designated). If yes (Y), the process proceeds to ST25, and, if no (N), the process proceeds to ST26.

In ST25, the discharge device switching gate GT1 is set at the main body tray discharge position for discharging the sheet to the main body discharge tray TRh. Then, the process proceeds to ST27.
In ST26, the discharge device switching gate GT1 is set at the optional discharge position for discharging the sheet to the optional discharge tray (optional face down tray TRh1, TRh1 ′ or optional face up tray TRh2). Then, the process proceeds to ST27.
In ST27, it is determined whether or not the job is finished. If no (N), ST27 is repeated, and if yes (Y), the process returns to ST21.

In ST28, it is determined whether or not the optional discharge unit U6 is attached. If no (N), the process proceeds to ST29, and if yes (Y), the process proceeds to ST30.
In ST29, normal double-sided printing gate switching processing is executed. That is, when a sheet on which an image is recorded during duplex printing is guided to the main body discharge tray TRh side, the discharge device switching gate GT1 is set at the main body tray discharge position, and the sheet is moved from the main body discharge tray TRh side to the sheet reversing device U3 side. Is guided, the discharge device switching gate GT1 is set at the reversing device conveyance position. Then, the process proceeds to ST21.

In ST30, it is determined whether or not the main body discharge tray TRh is designated as a tray for discharging sheets. If yes (Y), the process proceeds to ST31, and, if no (N), the process proceeds to ST32.
In ST31, when the main body discharge tray is designated, which is a switching process of the discharge device switching gate GT1 when performing duplex printing using the optional discharge unit U6 and discharging to the main body discharge tray TRh (or finisher U4) A switching process (refer to a subroutine of FIG. 18 described later) is executed. Then, the process returns to ST21.
In ST32, an optional discharge tray which is a switching process of the discharge device switching gate GT1 when discharging a double-side printed sheet to an optional discharge tray (option face down tray TRh1, TRh1 'or option face up tray TRh2) designated by the user. When designated, double-sided printing gate switching processing (see a subroutine of FIG. 19 described later) is executed. Then, the process returns to ST21.

(Explanation of double-sided printing gate switching process when main body discharge tray is specified)
FIG. 18 is a flowchart of the double-sided printing gate switching process when the main body discharge tray is designated, and is a flowchart of the subroutine of ST31 in FIG.
In ST41 of FIG. 18, it is determined whether the sheet that has passed through the fixing device F has been printed on both sides. If yes (Y), the process proceeds to ST42, and, if no (N), the process proceeds to ST45.
In ST42, the discharge device switching gate GT1 is set to the main body tray discharge position. Then, the process proceeds to ST43.

In ST43, it is determined whether or not the trailing end in the sheet conveyance direction of the sheet discharged to the main body discharge tray has passed the position of the discharge device switching gate GT1. If no (N), ST43 is repeated, and if yes (Y), the process proceeds to ST44.
In ST44, it is determined whether or not the job is finished. If NO (N), the process returns to ST41, and if YES (Y), the double-sided printing gate switching process at the time of specifying the main body discharge tray in FIG. 18 is terminated, and the process returns to the discharge apparatus switching gate switching process in FIG.

In ST45, the discharge device switching gate GT1 is set to the optional discharge position. Then, the process proceeds to ST46.
In ST46, it is determined whether or not the trailing end in the sheet conveyance direction of the sheet conveyed to the optional discharge unit U6 has passed the position of the discharge device switching gate GT1. If no (N), ST46 is repeated, and if yes (Y), the process proceeds to ST47.
In ST47, the discharge device switching gate GT1 is set to the main body tray discharge position. Then, the process proceeds to ST48.

In ST48, it is determined whether or not the sheet that has passed through the fixing device F has been printed on both sides. If yes (Y), the process proceeds to ST43, and, if no (N), the process proceeds to ST49.
In ST49, it is determined whether or not the trailing end in the sheet conveyance direction of the sheet conveyed to the sheet reversing device U3 has passed the position of the discharge device switching gate GT1. If no (N), ST49 is repeated, and if yes (Y), the process moves to ST45.

(Explanation of double-sided gate switching process when optional discharge tray is specified)
FIG. 19 is a flowchart of the double-sided printing gate switching process when the main body discharge tray is specified, and is a flowchart of the subroutine of ST32 in FIG.
In ST61 of FIG. 19, the discharge device switching gate GT1 is set to the optional discharge position. Then, the process proceeds to ST62.
In ST62, it is determined whether or not the rear end in the sheet conveyance direction of the sheet on which the image is recorded has passed through the discharge device switching gate GT1 from below to above. If no (N), ST62 is repeated, and if yes (Y), the process proceeds to ST63.
In ST63, it is determined whether or not the sheet that has passed through the discharge device switching gate GT1 is a sheet that has been printed on both sides. If no (N), the process moves to ST64, and if yes (Y), the process moves to ST66.

In ST64, the discharge device switching gate GT1 is set at the main body discharge tray discharge position. Then, the process proceeds to ST65.
In ST65, whether or not the rear end of the sheet conveyed in the sheet reversing device U3 has passed through the position of the discharge device switching gate GT1 from the upper side (optional discharge unit U6 side) to the lower side (sheet reversing device U3 side). Is determined. If no (N), ST65 is repeated, and if yes (Y), the process proceeds to ST66.
In ST66, it is determined whether or not the job is finished. If no (N), the process returns to ST61, and if yes (Y), the double-sided printing gate switching process at the time of option discharge tray designation in FIG. 19 ends, and the process returns to the discharge apparatus switching gate switching process in FIG.

(Operation of Example 1)
In the image forming apparatus U of Example 1 having the above-described configuration, the toner image formed on the surface of the photoconductor PR is transferred to the sheet by the transfer roll Rt and is fixed by the fixing device F. Then, when the finisher U4, the finisher conveying device U5, and the optional discharge unit U6 are not mounted (the case shown in FIGS. 1 and 2), the sheet after the toner image is fixed is discharged to the main body discharge tray TRh. When the finisher U4, the finisher transport device U5, and the optional discharge unit U6 are mounted (in the case shown in FIG. 4), the discharge trays specified by the user (option face down trays TRh1, TRh1 ′, option face up tray TRh2, top The tray U4a, the stack tray of the end binding device U4b, and the discharge tray of the saddle stitching device U4c).

FIG. 20 is an explanatory diagram of a sheet conveyed through the sheet path during duplex printing according to the first exemplary embodiment. FIG. 20A is a diagram illustrating a state immediately after the first sheet is fed, and FIG. 20B is a second sheet. FIG. 6 is a diagram illustrating a state immediately after a sheet is fed.
FIG. 21 is an explanatory diagram of a sheet conveyed through the sheet path during double-sided printing according to the first exemplary embodiment. FIG. 21A illustrates a state immediately after the third sheet is fed, and FIG. 21B illustrates the first sheet. FIG. 6 is a diagram illustrating a state in which a second sheet passes above the discharge device switching gate while the sheet passes below the discharge device switching gate.
FIG. 22 is an explanatory diagram of a sheet conveyed through the sheet path during duplex printing according to the first exemplary embodiment, and illustrates a state in which the third sheet is conveyed to the optional discharge unit.

20 to 22, in the image forming apparatus U according to the first embodiment, when the optional discharge unit U6 is mounted, when duplex printing is designated and the finisher U4 is designated to perform post-processing, Double-sided printing is executed using the discharge unit U6 (see FIGS. 16 and 18).
In FIG. 20A, the immediately preceding sheet is not conveyed immediately after the start of the job, so the first sheet S1 is fed by the processing of ST11, ST12, and ST16 of FIG. When printing is performed on the first surface of the first sheet S1, the discharge device switching gate GT1 is moved to the optional discharge position (position shown in FIG. 20A) by the processing of ST41 and ST45 in FIG. 18, and the sheet S1 is optional. It is conveyed to the discharge unit U6 (see FIG. 20B).

  When the rear end of the first sheet S1 in the sheet conveyance direction passes the discharge device switching gate GT1, the discharge device switching gate GT1 is moved to the main body tray discharge position (position shown in FIG. 20B) by the processing of ST46 and ST47 in FIG. To do. In FIG. 20B, when the first sheet S1 is conveyed to a predetermined position, the face-down discharge roller 28 is reversely driven to switch back the first sheet S1. Accordingly, the first sheet S1 switched back by the option discharge unit U6 is guided to the sheet reversing path SH1.

  At this time, when the rear end in the sheet conveyance direction of the first sheet S1 passes through the duplex printing paper feed position, the second sheet S2 is fed by the processes of ST11 to ST13, ST15, and ST16 of FIG. The Note that the double-sided printing paper feed position varies depending on the sheet size (A4, B5, etc.) to be fed.

The first sheet S1 is conveyed to the sheet reversing path SH1, and the rear end of the first sheet S1 moves upward from the discharge device switching gate GT1 (optional discharge unit U6 side) to the left (sheet reversing path SH1 side). When passing, the discharge device switching gate GT1 is moved to the optional discharge position (position shown in FIG. 20A) by the processing of ST48, ST49, and ST45 in FIG. Therefore, the second sheet S2 that has passed through the fixing device F is guided to the optional discharge unit U6. At this time, since the interval between the first sheet S1 and the second sheet S2 is the double-sided printing paper feeding interval, the second sheet after the rear end of the first sheet S1 passes. The sheet S2 is conveyed to the discharge device switching gate GT1.
In FIG. 21A, when the trailing edge of the second sheet S2 passes through the discharge device switching gate GT1, the discharge device switching gate GT1 is moved to the main body tray discharge position (position shown in FIG. 21A) by the processing of ST46 and ST47 in FIG. Moving.

  In FIG. 21A, when the rear end in the sheet conveyance direction of the first sheet S1 that has passed through the sheet reversing path SH1 and retransmitted to the transfer area Q3 passes through the inter-sheet feedable position, ST11 to ST14 in FIG. Through the process of ST16, the third sheet S3 is fed. The inter-sheet feedable position varies depending on the trays TR1 to TR4 to be fed, but a predetermined interval (interval for margin) from the rear end of the preceding sheet (in this case, the first sheet S1). The position at which the third sheet can be conveyed continuously with the gap opened can be set as the inter-sheet feedable position.

  In FIG. 21B, since the first sheet S1 that has passed through the fixing device F has recorded the second image (double-sided printed), the discharge device switching gate moved to the main body tray discharge position in ST48 and ST43 in FIG. It is guided by the lower right surface of GT1 and conveyed to the finisher conveyance path SH2. At this time, the second sheet S2 switched back by the face-down discharge roller 28 is guided by the upper left surface of the discharge device switching gate GT1 and conveyed to the sheet reversing path SH1. That is, the first sheet S1 passes from the lower side (fixing device F side) to the right side (main body discharge tray TRh side) below the discharge device switching gate GT1, and the second sheet passes above the discharge device switching gate GT1. Sheet S2 passes from the top to the left.

  In FIG. 22, when the trailing edge of the first sheet S1 passes the discharge device switching gate GT1, the discharge device switching gate GT1 is moved to the optional discharge position (position shown in FIG. 22) by the processing of ST43, ST41, and ST45 in FIG. ) Therefore, the third sheet S3 is guided by the discharge device switching gate GT1 and conveyed to the optional discharge unit U6. When there are fourth and subsequent image data, the states of FIGS. 21A to 22 are repeated until the job is completed.

  Therefore, in the prior art in which the sheet is not reversed using the optional discharge unit U6, the main body discharge roller R1 is used to perform the switchback, so that the trailing edge of the immediately preceding sheet is the discharge device switching gate GT1. The next sheet could not enter the discharge device switching gate GT1 until it passed. However, in the image forming apparatus U of the first embodiment, since the sheet is reversed using the optional discharge unit U6, double-sided printing is performed during the switchback of the second sheet S2, as shown in FIG. 21B. The completed first sheet can enter the discharge device switching gate GT1 and be discharged.

  As a result, the image forming apparatus U according to the first exemplary embodiment can shorten the sheet interval during double-sided printing, as compared with the conventional technique in which the next sheet must be fed until the immediately preceding sheet passes. The interval between the sheets to be fed can be shortened, and the image forming speed (productivity) can be improved. Further, in the image forming apparatus U according to the first exemplary embodiment, the conveyance from the optional discharge unit U6 to the sheet reversing path SH1 and the conveyance from the fixing device F to the main body discharge tray TRh are performed by one discharge device switching gate GT1. Can do. Therefore, the number of parts can be reduced and the cost can be reduced.

  In the image forming apparatus U according to the first embodiment, the face-up tray is not attached to the image forming apparatus body U1, but the face-up tray (option face-up tray TRh2) is attached to the option discharge unit U6. Therefore, compared with the conventional case where the face-up tray is installed in the sheet reversing device U3 of the image forming apparatus U1, the horizontal width (length in the Y-axis direction) of the entire image forming apparatus U can be made compact. Further, since the option face-up tray TRh2 is detachable and rotatable by the tray support shafts 47 and 48, when the option face-up tray TRh2 is not used, the image can be removed or rotated upward to obtain an image. The lateral width of the forming apparatus U can be further reduced. As a result, the image forming apparatus U can be downsized.

  Further, in the option discharge unit U6 according to the first embodiment, the face-up tray TRh2 is mounted on the option discharge unit U6. Therefore, the face-up tray can be used for an image forming apparatus that does not include the face-up tray according to the needs of the user. TRh2 can be added. Accordingly, work such as replacement of parts of the image forming apparatus main body U1 and replacement of the sheet reversing apparatus U3, which are necessary when the face-up tray is mounted on an image forming apparatus that does not include the face-up tray, is omitted. The configuration can be simplified and the cost can be reduced. Further, in the option discharge unit U6 of the first embodiment, the option face-up tray TRh2 is detachably mounted, so that the face-up tray can be easily added.

Further, the optional discharge unit U6 according to the first embodiment can automatically determine whether or not the sheet can be discharged to the face-up tray TRh2 by the tray detection sensor SN1. Therefore, when the sheet cannot be discharged to the face-up tray TRh2, it is possible to prevent the sheet from being erroneously discharged.
Further, in the optional discharge unit U6 of the first embodiment, even when the face-up side case 2 is opened with respect to the face-down side case 1 by the placement surface angle holding link mechanism L, the sheet placement surface 71a is above the horizontal. The angle is held at a predetermined angle. Therefore, even if the face-up side case 2 is opened while the sheets are stacked on the sheet placement surface 71a, it is possible to prevent the sheets from falling from the optional face-up tray TRh2. As a result, when a jam (paper jam) occurs in the face-down transport path 61, the face-up transport path 62, or the common transport path 64, the jammed paper is jammed without removing the sheets stacked on the optional face-up tray TRh2. The sheet can be removed, and the work becomes easier.

  Further, in a state where the face-up side case 2 is opened with respect to the face-down side case 1, the opening-time engaging portion 54c is engaged with the gate position holding engaging portion 48b of the tray angle holding plate 48, and the tray switching gate. 54 is held at the face-up discharge position (position shown in FIG. 9B). Therefore, when a paper jam occurs in the face-up conveyance path 62, the jammed sheet can be easily removed because the face-up conveyance path 62 is opened with the face-up side case 2 opened. If a jam (paper jam) occurs in the face-down conveyance path 61 or the common conveyance path 64, the jammed sheet can be easily removed by simply opening the face-up side case 2.

The optional discharge unit U6 according to the first exemplary embodiment is mounted from the side (left side) with respect to the image forming apparatus main body U1, and is positioned, locked, and electrically connected when mounted. Therefore, even in a copier (image forming apparatus U) having an IIT, the optional discharge unit U6 can be easily mounted without removing the IIT.
Further, since the option discharge unit U6 of the first embodiment has an offset discharge function, it can be discharged to the option face down trays TRh1 and TRh1 ′. Therefore, when the main body discharge roller R1 of the image forming apparatus main body U1 has no offset discharge function, the offset discharge function can be added according to the needs of the user by mounting the optional discharge unit U6.

  Further, in the image forming apparatus U according to the first exemplary embodiment, when the finisher U4 (post-processing apparatus) is mounted, the sheet conveying path inside the image forming apparatus main body U1 is changed, or a sheet conveying path for the finisher is provided in advance. Even if there is no problem, the finisher U4 can be used by mounting the finisher transport device U5. In the finisher transport device U5 of the first embodiment, only the finisher transport path SH2 is formed inside, and the gate and the transport roller for discharging the sheet are not provided in the option face down tray TRh1 on the upper surface. Therefore, the optional discharge tray TRh1 and the finisher transport path SH2 can be added with a simple configuration and low cost, and since there is no gate or the like, it is possible to prevent the optional discharge tray TRh1 from being reduced in length in the sheet discharge direction. Further, since the configuration is simple, the interval between the finisher transport path SH2 and the option face down tray TRh1 can be narrowed, and the interval between the option face down tray TRh1 and the lower surface of the IIT can be widened. Therefore, the number of sheets that can be stacked on the option face down tray TRh1 can be increased, and when the user takes out the sheets stacked on the option face down tray TRh1, the takeout opening becomes wide and the takeout becomes easy.

  Further, in the image forming apparatus U according to the first embodiment, the optional discharge unit U6 and the face-up tray TRh2 can be mounted according to the number of trays required by the user. Even if the required number fluctuates, the optional discharge unit U6 and the face-up tray TRh2 can be easily added or removed, and the user's needs can be appropriately handled. Further, the number of the face-down trays TRh1 and TRh1 ′ and the number of the face-up trays TRh2 can be easily adjusted according to the needs of the user. In addition, compared to a conventional unit having an unnecessarily large number of discharge devices and trays, the cost burden and work burden according to the required number of users can be set, and the overall cost burden can be suppressed. Furthermore, since the optional discharge unit U6 and the discharge trays TRh1 ′ and TRh2 that are no longer necessary can be removed, the entire image forming apparatus can be prevented from becoming unnecessarily large or heavy.

FIG. 23 is an explanatory cross-sectional view of a main part of the image forming apparatus according to the second embodiment.
FIG. 24 is a perspective explanatory view of the optional discharge unit of the second embodiment and corresponds to FIG. 6A of the first embodiment.
In the description of the second embodiment, components corresponding to those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
The second embodiment is different from the first embodiment in the following points, but is configured in the same manner as the first embodiment in other points.
In FIG. 23, a total of three optional discharge units U6 ′ are mounted on the printer U ′ as the image forming apparatus of the second embodiment. 23 and 24, a rear upper surface cover 111 is mounted on the upper surface of the rear end portion of the face-down side case 1 'of the optional discharge unit U6' of the second embodiment, and the front upper surface cover is disposed on the upper surface of the front end portion. 112 is attached.

  When the rear upper surface cover 111 is removed, the additional mounting rear concave portion 1b formed at the rear end of the face down side case 1 'is exposed, and when the front upper surface cover 112 is removed, the face down side case 1' The additional mounting front recess 1c formed at the front end is exposed. The additional mounting rear concave portion 1b includes an additional mounting connector (upper detachable portion) U11 'configured similarly to the main body side connector U11, a rear option discharge unit positioning hole (upper detachable portion) U16', A rear option discharge unit lock pin (upper detachable portion) U18 'is provided. The additional mounting front recess 1c is provided with a front option discharge unit positioning hole (upper detachable portion) U17 'and a front option discharge unit lock pin (upper detachable portion) U19'.

  Accordingly, the optional discharge unit U6 ′ of the second embodiment includes the additional mounting connector U11 ′, the optional discharge unit positioning holes U16 ′ and U17 ′, and the optional discharge unit lock pin U18 disposed on the upper surface of the face-down side case 1 ′. Corresponding to ′ and U19 ′, a mounting lock member (lower attaching / detaching portion) 16 and positioning pins (lower attaching / detaching portions) 18, 18 at the time of mounting are arranged downward (not shown). The main body side connector (upper detachable part) U11 of the printer main body U1 ', the optional discharge unit positioning holes (upper detachable part) U16, U17, and the optional discharge unit lock pins (upper detachable part) U18, U19 are the optional discharge unit. It is provided on the upper end surface according to the mounting lock member 16 of U6 ′ and the positioning pins 18 and 18 at the time of mounting. Accordingly, the option discharge unit U6 ′ according to the second embodiment is mounted on the printer main body U1 ′ or the option discharge unit U6 ′ from above, unlike the first embodiment, which is mounted on the printer main body U1 ′ from the left (side). . And it connects electrically with a connector at the time of mounting | wearing. When the optional discharge unit U6 ′ according to the second embodiment is mounted on the printer main body U1 ′ or the optional discharge unit U6 ′, the front cover 3 and the rear cover 4 are mounted without being removed.

  In FIG. 25, in the printer U ′ of the second embodiment, an option face down tray (option discharge tray, discharge tray) TRh4 is mounted on the rear end portion of the printer main body U1 ′, and an option is mounted on the rear end portion of the option face down tray TRh4. A face-down tray (optional discharge tray, discharge tray) TRh5 is mounted. Above that, an optional face-down tray (option discharge tray, discharge tray) TRh6 for small size is mounted.

(Operation of Example 2)
In the printer (image forming apparatus) U ′ according to the second embodiment having the above-described configuration, an optional discharge unit U6 ′ can be added by mounting sequentially from above. Therefore, the number of option face-up trays TRh2 and option face-down trays TRh4 to TRh6 can be easily increased / decreased as required by the user.

(Example of change)
As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the said Example, A various change is performed within the range of the summary of this invention described in the claim. It is possible. Modification examples (H01) to (H05) of the present invention are exemplified below.
(H01) In each of the embodiments described above, the present invention is not limited to an electrophotographic image forming apparatus, and can be applied to an inkjet recording image forming apparatus.
(H02) In each of the above embodiments, the common conveyance path sheet conveyance roller 60 is provided at the lower end portion of the optional discharge units (option discharge members) U6, U6 ′, but may be installed at the upper end portion of the image forming apparatus body U1. It is also possible to arrange at the upper end of the optional discharge unit U6 ′.

(H03) In each of the embodiments, the sheet reversing path SH1 is provided in the sheet reversing unit that can be attached to and detached from the image forming apparatus main bodies U1 and U1 ′. However, the sheet reversing path SH1 may be provided in the image forming apparatus main body.
(H04) In each of the above embodiments, the tray switching gate 54 is disposed at a position where the face-down conveyance path 61 and the face-up conveyance path 62 branch from the common conveyance path 64. The face-down branch position where the path 61 branches and the face-up branch position where the face-up transport path 62 branches from the common transport path 64 are shifted in the vertical direction, and tray switching gates are respectively set at the face-down branch position and the face-up branch position. It is also possible to arrange.

(H05) In the second embodiment, the option discharge unit mounted on the printer is not limited to the option discharge unit U6 ′ mounted from above, but as in the first embodiment, the option discharge unit U6 mounted from the side. Can also be used. In this case, for example, connectors similar to the main body side connector U11 can be provided in the option face-down trays TRh4 to TRh6. In this case, since the optional discharge unit U6 can be mounted on a copying machine and a printer, the optional discharge unit U6 can be shared.

1 is a perspective explanatory view of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is an explanatory diagram of the image forming apparatus according to the first embodiment. 3A and 3B are perspective explanatory views for explaining a state in which the optional discharge unit is attached to the image forming apparatus of the present invention, FIG. 3A is an overall perspective explanatory view, and FIG. FIG. 3C is an enlarged explanatory view of the main part viewed from the direction of arrow IIIC in FIG. 3A. FIG. 4 is an explanatory diagram of an image forming apparatus equipped with a sheet post-processing apparatus and an optional discharge unit. FIG. 5 is a perspective explanatory view seen from the face-down tray side of the optional discharge unit to which the face-up tray is attached. 6A and 6B are perspective explanatory views as seen from the face-up tray side of the optional discharge unit, FIG. 6A is a perspective explanatory view when the face-up tray is not mounted, and FIG. 6B is a perspective explanatory view when the face-up tray is mounted. It is. FIG. 7 is a front end view of the optional discharge unit. FIG. 8 is a rear end view of the optional discharge unit. FIG. 9 is a cross-sectional explanatory view of the main part of the optional discharge unit, FIG. 9A is a cross-sectional explanatory view of the main part when the face-up tray is not mounted, and FIG. FIG. FIG. 10 is an explanatory perspective view of the optional discharge unit with the upper end portion opened. FIG. 11 is a front end view of the optional discharge unit with its upper end opened, and corresponds to FIG. FIG. 12 is a rear end view of the option discharge unit with the upper end opened, and corresponds to FIG. FIG. 13 is a rear end view of the option discharge unit with the option face-up tray rotated upward, and corresponds to FIG. FIG. 14 is a block diagram (functional block diagram) illustrating functions provided in the control unit of the image forming apparatus according to the first exemplary embodiment. FIG. 15 is a main flowchart of the sheet feeding process of the image forming apparatus according to the first exemplary embodiment. FIG. 16 is a flowchart of the double-sided printing paper feed process when the main body discharge tray is specified in the first embodiment, and is a flowchart of the subroutine of ST7 in FIG. FIG. 17 is a main flowchart of the discharge device switching gate switching process of the image forming apparatus according to the first embodiment. FIG. 18 is a flowchart of the double-sided printing gate switching process when the main body discharge tray is designated, and is a flowchart of the subroutine of ST31 in FIG. FIG. 19 is a flowchart of the double-sided printing gate switching process when the main body discharge tray is specified, and is a flowchart of the subroutine of ST32 in FIG. FIG. 20 is an explanatory diagram of a sheet conveyed through the sheet path during duplex printing according to the first exemplary embodiment. FIG. 20A is a diagram illustrating a state immediately after the first sheet is fed, and FIG. 20B is a second sheet. FIG. 6 is a diagram illustrating a state immediately after a sheet is fed. FIG. 21 is an explanatory diagram of a sheet conveyed through the sheet path during double-sided printing according to the first exemplary embodiment. FIG. 21A illustrates a state immediately after the third sheet is fed, and FIG. 21B illustrates the first sheet. FIG. 6 is a diagram illustrating a state in which a second sheet passes above the discharge device switching gate while the sheet passes below the discharge device switching gate. FIG. 22 is an explanatory diagram of a sheet conveyed through the sheet path during duplex printing according to the first exemplary embodiment, and illustrates a state in which the third sheet is conveyed to the optional discharge unit. FIG. 23 is an explanatory cross-sectional view of a main part of the image forming apparatus according to the second embodiment. FIG. 24 is a perspective explanatory view of the optional discharge unit of the second embodiment and corresponds to FIG. 6A of the first embodiment.

Explanation of symbols

1a, U12; 1a, U11 ', U16'-U19' ... upper detachable part,
19; 16, 18, 19 ... Lower attachment / detachment part,
54 ... Tray switching gate,
61, 62 ... Optional discharge path,
63 ... Upper conveyance path,
64 ... common conveyance path,
R1 ... main body discharge member,
TRh ... main unit discharge tray,
TRh1, TRh1 ', TRh2; TRh2, TRh4 to TRh6 ... discharge tray,
TRh1, TRh1 '; TRh4 to TRh6 ... Face down tray,
TRh2 ... Face-up tray,
U1 ... Image forming apparatus main body,
U6; U6 '... Optional discharge device.

Claims (3)

An optional discharge device comprising the following configuration requirements (A01) to (A06);
(A01) An upper attachment / detachment portion provided at the upper end portion of the option discharge device and configured to be attachable / detachable to / from a lower attachment / detachment portion of another option discharge device disposed above.
(A02) a lower attachment / detachment portion provided at the lower end portion of the option discharge device and configured to be attachable / detachable with respect to an upper attachment / detachment portion of another option discharge device disposed below;
(A03) a common conveyance path through which a sheet conveyed from another optional discharge device disposed below is conveyed;
(A04) An optional discharge path that is connected to the common conveyance path and that conveys the sheet discharged to the discharge tray;
(A05) An upper conveyance path that is connected to the common conveyance path and that conveys a sheet conveyed to another optional discharge device disposed above.
(A06) A tray discharge position that is disposed at a connection portion of the common conveyance path, the option discharge path, and the upper conveyance path, and conveys a sheet to the option discharge path, and an upper conveyance position that conveys the sheet to the upper conveyance path Transfer path switching gate that can move between the two. The optional discharge device according to claim 1, comprising the following constituent elements (A07) and (A08):
(A07) a face-down conveyance path for conveying the sheet to a face-down tray from which the sheet is discharged in a face-down state in which the image recording surface on which the image is recorded is the bottom surface;
A face-up conveyance path for conveying a sheet to a face-up tray from which the sheet is discharged in a face-up state in which the image recording surface is an upper surface;
Said optional discharge path, having
(A08) A face-up discharge position as the tray discharge position for discharging a sheet to the face-up tray, a face-down discharge position as the tray discharge position for discharging a sheet to the face-down tray, and the upper transport position The transfer path switching gate that can move between the two. An image forming apparatus comprising the following structural requirements (B01) to (B03):
(B01) a main body discharge tray provided in the main body of the image forming apparatus and on which a sheet on which an image is recorded is discharged;
(B02) a main body discharge member for discharging the sheet to the main body discharge tray;
(B03) an upper attachment / detachment portion provided at the upper end portion of the option discharge device and configured to be attachable / detachable with respect to a lower attachment / detachment portion of another option discharge device disposed above;
A lower attachment / detachment portion provided at a lower end portion of the option discharge device and configured to be attachable / detachable to another option discharge device disposed below or an upper attachment / detachment portion of the image forming apparatus main body;
A common conveyance path through which a sheet conveyed from another optional discharge device disposed below or the image forming apparatus main body is conveyed;
An optional discharge path connected to the common conveyance path, through which a sheet discharged to a discharge tray is conveyed;
An upper conveyance path that is connected to the common conveyance path and that conveys a sheet conveyed to another optional discharge device disposed above;
Between the tray discharge position that conveys the sheet to the optional discharge path and the upper conveyance position that conveys the sheet to the upper conveyance path, which is disposed at a connection portion of the common conveyance path, the option discharge path, and the upper conveyance path A transfer path switching gate that can be moved,
With optional discharge device.

Images