JP2005289540A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the cost of an image forming device equipped with a face up tray and a face down tray. <P>SOLUTION: The image forming device comprises a face down discharge member (28) discharging the sheet to the face down tray, a face up discharge member (51) discharging the sheet to the face up tray (TRh2), a face down carrying path (61) carrying the sheet to the face down tray (TRh1), a face up carrying path (62) carrying the sheet to the face up tray (TRh2), and a tray switching gate (54) carrying the sheet carried in the common carrying path (63) by switching the face down carrying path (61) or the face up carrying path (62). The image forming device is equipped with an optional discharge device (U6) detachably mounted to the upper part of the main body discharge member (R1). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a FAX, a printer, and a copying machine, and more particularly to an image forming apparatus that can include a plurality of sheet discharge trays for discharging sheets.

  2. Description of the Related Art Conventionally, an image forming apparatus having a plurality of sheet discharge trays for discharging a sheet on which an image is recorded is known. As the sheet discharge tray, a face-down tray that discharges sheets in a state where the image recording surface (second surface during double-sided printing) on which an image is recorded is a lower surface (so-called face-down state), and the image recording surface is an upper surface And a face-up tray in which sheets are discharged in a state (face-up state). The following prior art (J01) is known as an image forming apparatus provided with two discharge trays of the face-up tray and the face-down tray.

(J01) Technology described in Patent Document 1 (Japanese Patent Laid-Open No. 7-315668) Patent Document 1 describes an image forming apparatus including a face-up tray (16) and a face-down tray (18). Furthermore, there is described an image forming apparatus in which a sorter (40) having a plurality of trays (47) is mounted on the upper surface of the image forming apparatus.

Japanese Patent Laid-Open No. 7-315668 ("0011" to "0020", FIG. 1)

  However, in the prior art (J01), when the face-up tray and the face-down tray are provided in the image forming apparatus, the face-up transport path for transporting the sheet to the face-up tray and the face for transporting the sheet to the face-down tray It is necessary to provide a down conveyance path in the main body of the image forming apparatus. Therefore, there is a problem that the configuration of the image forming apparatus main body becomes complicated and the cost increases. In addition, since the face-up conveyance path and the face-down conveyance path are provided in the image forming apparatus main body, for example, an image forming apparatus having only a face-down tray and no face-up tray can be used later. It was difficult to add a face-up conveyance path.

  Furthermore, in order to enable double-sided printing in the image forming apparatus, when a sheet reversing unit in which a sheet reversing path for reversing the sheet is formed is added, the sheet reversing unit is supported on the side surface of the image forming apparatus. . In such an image forming apparatus capable of duplex printing, the face-up tray is usually mounted on the side wall of the sheet reversing unit. Accordingly, in the case of such an image forming apparatus capable of double-sided printing, there is a problem that it is difficult to reduce the size of the image forming apparatus because the width of the entire image forming apparatus is increased by the sheet reversing unit and the face-up tray.

  Further, as described above, in the conventional image forming apparatus, the face down tray and the face up tray are usually installed in the image forming apparatus main body (or the sheet reversing unit). The optional discharge device such as a sorter mounted on the upper surface of the described image forming apparatus has conventionally been provided with only one of the face-up tray and the face-down tray.

In view of the above-described circumstances, the present invention has the following contents (O01) to (O03) as technical problems.
(O01) To reduce the cost of an image forming apparatus having a face-up tray and a face-down tray.
(O02) Make it possible to easily add a face-up tray.
(O03) To downsize an image forming apparatus including a face-up tray and a face-down tray.

(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 above technical problem, the image forming apparatus of the first invention is characterized by comprising the following structural requirements (A01) to (A03).
(A01) A main body discharge tray (TRh) provided in the image forming apparatus main body (U1, U1 ′) and on which a sheet on which an image is recorded is discharged,
(A02) A main body discharge member (R1) for discharging a sheet to the main body discharge tray (TRh),
(A03) a face-down discharge member (28) for discharging a sheet to a face-down tray (TRh1, TRh3 to TRh5) from which the sheet is discharged in a face-down state in which an image recording surface on which an image is recorded is a lower surface;
A face-up discharge member (51) for discharging 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 the upper surface;
A common conveyance path (63) through which a sheet conveyed from the image forming apparatus main body (U1, U1 ′) is conveyed;
A face-down conveyance path (61) connected to the common conveyance path (63) and conveying a sheet to the face-down trays (TRh1, TRh3 to TRh5);
A face-up conveyance path (62) connected to the common conveyance path (63) and conveying a sheet to the face-up tray (TRh2);
A tray switching gate (54) for switching and conveying the sheet conveyed through the common conveyance path (63) to the face-down conveyance path (61) or the face-up conveyance path (62);
And an optional discharge device (U6, U6 ′) that is detachably mounted above the main body discharge member (R1).

(Operation of the first invention)
In the image forming apparatus according to the first aspect of the present invention having the structural requirements (A01) to (A03), the main body discharge tray (TRh) provided in the image forming apparatus main body (U1, U1 ′) has a main body discharge member (R1). ) Discharges the sheet on which the image is recorded. The face-down discharge member (28) of the optional discharge device (U6, U6 ′) detachably mounted above the main body discharge member (R1) is in a face-down state in which the image recording surface on which the image is recorded is the lower surface. The sheet is discharged to the face-down tray (TRh1, TRh3 to TRh5) from which the sheet is discharged. Further, the face-up discharge member (51) of the optional discharge device (U6, U6 ′) discharges the sheet to the face-up tray (TRh2) where the sheet is discharged in a face-up state where the image recording surface is the upper surface. The sheet conveyed from the image forming apparatus main body (U1, U1 ′) and conveyed through the common conveyance path (63) is conveyed to the face-down trays (TRh1, TRh3 to TRh5) by the tray switching gate (54). The face-down conveyance path (61) or the face-up conveyance path (62) for conveying the sheet to the face-up tray (TRh2) is switched and conveyed.

  Therefore, in the image forming apparatus according to the first aspect of the present invention, the face-down transport path (61) and the face-up transport path (62) are connected to the optional discharge devices (U6, U6 ') that can be attached to and detached from the image forming apparatus body (U1, U1'). The sheet can be discharged from the optional discharge device (U6, U6 ′) to the face-down tray (TRh1, TRh3 to TRh5) or the face-up tray (TRh2). Therefore, in the image forming apparatus of the first invention, when a face-up tray (TRh2) is added later to an image forming apparatus that is not provided with a face-up tray (TRh2), a sheet is placed on the face-up tray (TRh2). There is no need to replace parts or to provide parts in advance in order to add parts, members, and the like for conveyance to the inside of the image forming apparatus main body (U1, U1 ′). As a result, the configuration of the image forming apparatus main body (U1, U1 ′) and the entire image forming apparatus is simplified, and the cost can be reduced.

In the image forming apparatus according to the first aspect of the present invention, a sheet is discharged in a face-down state or a face-up state by additionally mounting a removable option discharge device (U6, U6 ′) as required by the user. Can be added. Therefore, a face-up discharge function and a face-down discharge function can be easily added.
In the image forming apparatus according to the first aspect of the invention, the face-up tray (TRh2) is provided for the optional discharge device (U6, U6 ′) mounted above the image forming apparatus body (U1, U1 ′). Compared with the prior art in which a face-up tray (TRh2) is provided on the side surface of the sheet reversing unit supported on the side surface of the image forming apparatus, the overall width of the image forming apparatus can be reduced, and the image forming apparatus can be downsized.

(First Embodiment 1)
An image forming apparatus according to Embodiment 1 of the first invention is characterized in that, in the first invention, the following configuration requirement (A04) is provided.
(A04) A face-up discharge position for discharging the sheet conveyed through the common conveyance path (63) to the face-up tray (TRh2), and a face-down for discharging the sheet to the face-down trays (TRh1, TRh3 to TRh5) The tray switching gate (54) movable between the discharge positions.

(Operation of Form 1 of the First Invention)
In the image forming apparatus according to the first aspect of the first invention having the configuration requirement (A04), the tray switching gate (54) transfers the sheet conveyed through the common conveyance path (63) to the face-up tray (TRh2). And a face-down discharge position for discharging sheets to the face-down trays (TRh1, TRh3 to TRh5). Therefore, a single tray switching gate (54) can switch between discharging sheets to the face-down trays (TRh1, TRh3 to TRh5) and discharging sheets to the face-up tray (TRh2). The cost can be reduced.

(First Embodiment 2)
An image forming apparatus according to a second aspect of the present invention is characterized in that, in the first aspect of the present invention or the first aspect of the first aspect, the following structural requirements (A05) and (A06) are provided.
(A05) a face-up tray support member (47, 49) for detachably supporting the face-up tray (TRh2);
A tray detection sensor (SN1) for detecting whether or not the face-up tray (TRh2) is mounted in a state where sheets can be discharged;
The optional discharge device (U6, U6 ′) having
(A06) The face-up tray (TRh2) having support member engaging portions (72, 73) that can be engaged with the face-up tray support members (47, 49).

(Operation of the second aspect of the first invention)
In the image forming apparatus according to the second aspect of the first invention having the structural elements (A05) and (A06), the face-up tray (TRh2) can be engaged with the face-up tray support members (47, 49). It has engagement parts (72, 73) and is detachably supported by the face-up tray support members (47, 49) of the optional discharge devices (U6, U6 ′). The tray detection sensor (SN1) of the optional discharge device (U6, U6 ′) detects whether or not the face-up tray (TRh2) is mounted in a state where sheets can be discharged.

  Accordingly, in the image forming apparatus according to the second aspect of the first invention, the face-up tray (TRh2) can be easily attached to and detached from the optional discharge device (U6, U6 ′), and is added later as the user needs. It can also be attached or used only during use, and removed when not in use. Since the tray detection sensor (SN1) can automatically detect whether or not the face-up tray (TRh2) is attached, the sheet is erroneously discharged toward the face-up tray (TRh2) that is not attached. Can be prevented.

(Embodiment 3 of the first invention)
An image forming apparatus according to a third aspect of the first invention is characterized in that, in the first invention or the first and second aspects of the first invention, the following configuration requirement (A07) is provided.
(A07) a face down side case (1, 1 ') for rotatably supporting the face down discharge member (28);
A face-up side case (2, 2 ') that rotatably supports the face-up discharge member (51);
A hinge shaft (6) connecting the lower end of the face-down side case (1, 1 ') and the lower end of the face-up side case (2, 2');
The optional discharge device has an upper end portion of the face-up side case (2, 2 ') and an upper end portion of the face-down side case (1, 1') around the hinge shaft (6). (U6, U6 ').

(Operation of the third aspect of the first invention)
In the image forming apparatus according to the third aspect of the first invention having the structural requirement (A07), a lower end portion of the face-down side case (1, 1 ') that rotatably supports the face-down discharge member (28); The lower end of the face-up side case (2, 2 ') that rotatably supports the face-up discharge member (51) is connected by a hinge shaft (6), and the face-up side around the hinge shaft (6) The upper end of the case (2, 2 ') and the upper end of the face-down side case (1, 1') are configured to be openable and closable. Therefore, when a paper jam occurs in the face-up conveyance path (62) or the face-down conveyance path (61), the upper end of the face-up side case (2, 2 ') and the face around the hinge axis (6) The jammed paper can be taken out by opening the upper end portion of the down case (1, 1 ').

(First aspect 4)
An image forming apparatus according to a fourth aspect of the present invention is characterized in that, in the third aspect of the first aspect of the present invention, the following structural requirements (A08) and (A09) are provided.
(A08) a face-up tray main body (71) provided with a sheet placement surface (71a) on which the discharged sheet is placed;
A mounting surface angle setting section (74) formed integrally with the face-up tray body (71);
The face-up tray (TRh2),
(A09) the face-up tray support member (47, 49) supported by the face-up side case (2, 2 ');
The sheet mounting surface (71a) is supported by the face up tray support members (47, 49) so as to be rotatable and engages with the mounting surface angle setting section (74) when the face up tray is mounted. A mounting surface angle holding member (48) for holding at a predetermined angle from the horizontal and the face down side case (1, 1 ') are rotatably supported and the mounting surface angle holding member (48) can be rotated. An angle holding member supporting arm (20) for supporting the face up side case (2, 2 ') with respect to the face down side case (1, 1') before and after opening and closing the seat. A mounting surface angle holding link mechanism (L) for holding the angle of the mounting surface (71a) at an angle upward from the horizontal;
The optional discharge device (U6, U6 ′) having

(Operation of the fourth aspect of the first invention)
In the image forming apparatus according to the fourth aspect of the first invention having the structural requirements (A08) and (A09), the mounting surface angle setting formed integrally with the face-up tray body (71) when the face-up tray is mounted. The part (74) engages with the mounting surface angle holding member (48) rotatably supported by the face-up tray support members (47, 49) supported by the face-up side case (2, 2 '). The sheet placement surface (71a) is held at a predetermined angle from the horizontal. An angle holding member support arm (20) of the optional discharge device (U6, U6 ') is rotatably supported by the face-down case (1, 1') and rotates the mounting surface angle holding member (48). Support as possible. The mounting surface angle holding link mechanism (L) having the mounting surface angle holding member (48) and the angle holding member support arm (20) is configured such that the face-up side case (2, 2 ') is connected to the face. The sheet placement surface (71a) is held at an angle upward from the horizontal before and after opening and closing with respect to the down-side case (1, 1 ').

  Therefore, in the state where the sheet is placed on the face-up tray (TRh2) supported by the face-up tray support members (47, 49) of the face-up side case (2, 2 ′), the face-up side case ( 2, 2 ′), the sheet placement surface (71a) of the face-up tray (TRh2) is held at an angle upward from the horizontal even when the face-up tray (TRh2) is opened and closed. Can be prevented. As a result, the operation of removing the jammed paper can be performed without taking out the sheets stacked on the face-up tray (TRh2), and the operation becomes easy.

(First embodiment 5)
An image forming apparatus according to a fifth aspect of the present invention is characterized in that, in the fourth aspect of the first aspect of the present invention, the following configuration requirement (A010) is provided.
(A010) the tray switching gate (54) supported by the face-up side case (2, 2 ');
An opening engaging portion (54c) integrally supported by the tray switching gate (54);
With the face-up side case (2, 2 ') being opened with respect to the face-down side case (1, 1'), the tray switching gate is engaged with the engaging portion (54c) when opened. The mounting surface angle holding link mechanism (L) having a gate position holding engagement portion (48b) for holding (54) at the face-up discharge position;
The optional discharge device (U6, U6 ′) having

(Operation of the fifth aspect of the first invention)
In the image forming apparatus according to the fifth aspect of the first invention having the structural element (A010), the tray switching gate (54) supported by the face-up side case (2, 2 ') has an engaging portion at the time of opening. (54c) is supported integrally. In the state where the face-up side case (2, 2 ') is opened with respect to the face-down side case (1, 1'), the gate position holding member of the mounting surface angle holding link mechanism (L). The joining portion (48b) engages with the engaging portion (54c) when opened, and holds the tray switching gate (54) at the face-up discharge position. Therefore, when the face-up side case (2, 2 ') is opened, the tray switching gate (54) is held at the face-up discharge position, and the face-up conveyance path (62) is held open. As a result, when a paper jam occurs in the face-up conveyance path (62), it is easy to remove the jammed sheet.

The above-described present invention has the following effects (E01) to (E03).
(E01) The cost of an image forming apparatus provided with a face-up tray and a face-down tray can be reduced.
(E02) A face-up tray can be easily added.
(E03) The image forming apparatus including the face-up tray and the face-down tray can be downsized.

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.
1 and 3, a top cover U1a is detachably attached to a left upper end portion of the sheet discharge tray TRh, and a left side cover U1b (see FIG. 3) is rotatably supported. The top cover U1a is removed when an optional discharge unit (U6) described later is mounted. In FIG. 3, when the top cover U1a is removed, the main body connector U11 (see FIG. 3A) and the upper left part of the IOT are exposed. Further, a unit right support frame U12 extending in the front-rear direction is provided on the exposed IOT. A rear bracket U13 (see FIG. 3B) is formed at the rear end of the 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, and normally contacts the right sheet guide SG1 by its own weight. Then, when the sheet conveyed from the fixing device F passes between the sheet guides SG1 and SG2, it receives a force from the conveyed sheet and rotates upward, and a conveyance path is formed between the sheet guide SG1 and the right sheet guide SG1. The sheet is formed and guided to the main body discharge roll R1. 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 the left sheet guide SG2 rotated to the right sheet guide SG1 side by its own weight, and is conveyed to the reversing 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.
4, the image forming apparatus U1 according to the first exemplary embodiment includes a finisher (sheet post-processing apparatus) U4 that performs post-processing of a sheet, and a finisher transport apparatus U5 that transports the sheet discharged from the paper discharge roll R1 to the finisher U4. An optional discharge unit (optional discharge device) U6 can be additionally mounted.
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.

An optional face down tray (optional discharge tray) TRh1 on which a sheet is placed is formed on the upper surface of the upper body U5b. 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.

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 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, a supported surface 19 that is supported on the upper surface of the image forming apparatus main body U1 when the image forming apparatus main body U1 is mounted is formed on the lower right side surface of the face-down side case 1.

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 is integrally formed at the left end portion (−Y side end portion) of the sensor support member 21, and the sensor support bent portion 21a is integrally formed with the sensor support bent portion 21a. 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 arranged side by side in the front-rear direction are integrally supported by the face down side case 1 at the left part (−Y side portion) of the face down side case 1. Has been. 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 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 option face-up tray TRh2 (see FIG. 6B) is not attached to the option discharge unit U6, the discharge port sealing cover 42 is attached to the left end surface (−Y end surface). 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 that are arranged in the front-rear direction (X-axis direction) and are integrally supported by the face-up side case 2 are provided at the lower right of the face-up discharge roller 51. And a tray switching gate (conveyance path switching gate) 54 supported so as to be rotatable about the rotation shaft 53. In FIG. 9, the tray switching gate 54 extends in the front-rear direction, and is connected to a connecting portion 54 a (see FIG. 10) that is rotatably supported by the rotary shaft 53 at both front and rear ends. A substantially triangular gate body 54b that is integrally connected to the connecting portion 54a, and an engagement portion 54c that is opened when protruding forward from the front end of the connecting portion 54a (see FIGS. 7, 10, and 11). ).

  In FIG. 9, the gate main body 54 b has a right face down guide surface 56 and a left face up guide surface 57. A solenoid and a spring (not shown) are connected to the tray switching gate 54, and a face-down discharge position (position shown in FIG. 9A) for discharging a sheet to the face-down tray TRh1 by on / off control of the solenoid, It is configured to be movable between a face-up discharge position (position shown in FIG. 9B) for discharging the sheet to the face-up tray TRh2. 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 conveyance roller 60.

  Accordingly, 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 conveyance path) is provided between the face-down guide surface 56 and the face-down sheet guide 31. 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 conveyance path) is provided between the face-up guide surface 57 and the face-up sheet guide 52. 62 is formed. Further, a common conveyance path (optional conveyance path) 63 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. Accordingly, by moving the tray switching gate 54 to the face-down discharge position or the face-up discharge position, the sheet conveyed upward on the common conveyance path 63 by the common conveyance path conveyance roller 60 is changed to the optional face-down tray TRh1 or the option It is discharged to the face-up tray TRh2.

  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.

(Explanation of mounting the optional discharge unit U6 to the image forming apparatus main body U1)
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 optional discharge unit U6 is brought close to the image forming apparatus main body U1 from which the 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, thereby positioning at the time of mounting. The 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.

(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 discharge roller R1 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 CL1 and CL2.

D3: Tray switching solenoid drive circuit The tray switching solenoid drive circuit D3 controls the on / off state of the solenoid for the tray switching gate 54 to move the tray switching gate 54 to the face-down discharge position (position shown in FIG. 9A). And the face-up discharge position (see FIG. 9B). The tray switching solenoid drive circuit D3 according to the first embodiment turns off the solenoid and keeps the tray switching gate 54 in the face-down discharge position by a spring at the normal time or when the optional face-down tray TRh1 is designated. . When the user designates the optional face-up tray TRh2, the tray switching solenoid drive circuit D3 turns on the solenoid 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 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 conveyance roller 60) is driven to rotate forward, and the optional normal rotation clutch CL3. Is turned off and the optional reverse rotation clutch CL4 is turned on, the optional discharge rollers 28, 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: Discharge tray designation storage means The discharge tray designation storage means C8 stores the main body discharge tray TRh, the optional face down tray TRh1, and the optional face up tray TRh2 in response to a user input with the discharge tray setting key UI6 of the user interface UI. Remember which one is specified. 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 moves the tray switching gate 54 to the face-down discharge position or face-up according to the tray (option face-down tray TRh1 or option face-up tray TRh2) designated by the user. Move to one of the discharge positions.

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 control the drive of the optional discharge rollers (the face-down discharge roller 28, the face-up discharge roller 51, and the common conveyance path conveyance roller 60). To do.

(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, a paper feed process 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 option discharge tray (option face down tray TRh1 or option face up tray TRh2) designated by the user. Execute. 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 through a sheet path (any one of the sheet conveying path SH, the sheet reversing path SH1, the face-down conveying path 61, and the common conveying path 63). 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 option discharge position for discharging the sheet to the option discharge tray (option face down tray TRh1 or option 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, both sides at the time of option discharge tray designation, which is a switching process of the discharge device switching gate GT1 when discharging a sheet printed on both sides to the option discharge tray (option face down tray TRh1 or option face up tray TRh2) designated by the user. A print gate switching process (refer to 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 attached (in the case shown in FIG. 4), the discharge tray specified by the user (the optional face down tray TRh1, the optional face up tray TRh2, the top tray U4a, It is discharged to 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 63, 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. When a jam (paper jam) occurs in the face-down conveyance path 61 or the common conveyance path 63, the jammed sheet can be easily removed simply by 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 tray 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.

FIG. 23 is a front view of the image forming apparatus according to the second embodiment. FIG. 23A is a front view in a state where an optional discharge unit is not mounted, and FIG. 23B is a front view in a state where one optional discharge unit is mounted.
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, the printer U ′ as the image forming apparatus according to the second embodiment omits the IIT and the automatic document feeder U2 as compared with the copying machine U according to the first embodiment. Accordingly, image formation (printing) is executed based on image data transmitted from an information processing apparatus such as a personal computer and discharge tray designation data. A top cover U1a ′ for protecting a main body side connector (not shown) configured similarly to the main body side connector U11 of the first embodiment is mounted on the upper end surface of the printer main body U1 ′ of the printer U ′ of the second embodiment. ing.

In FIG. 23B, in the printer U ′ of the second embodiment, the same option discharge unit U6 as the option discharge unit U6 of the first embodiment is mounted. The optional discharge unit U6 is mounted from the side and is electrically connected to the main body side connector.
An optional face down tray TRh3 is fixedly supported on the image forming apparatus main body U1 ′. The optional face-down tray TRh3 according to the second embodiment is supported by a plate-shaped tray main body 101 having a face-down sheet placement surface 101a on the upper surface and a rear end portion (−X end portion) of the image forming apparatus main body U1 ′. And a main body mounting portion 102.
The printer U ′ according to the second embodiment does not have the IIT support frame extending in the vertical direction unlike the copying machine U according to the first embodiment. Therefore, when the optional discharge unit U6 is mounted on the printer main body U1 ′. The front cover 3 and the rear cover 4 are attached to the printer body U1 ′ without being removed.

(Operation of Example 2)
In the image forming apparatus (printer) U ′ of the second embodiment having the above-described configuration, the sheet is discharged to either the main body discharge tray TRh, the option face-down tray TRh3, or the option face-up tray TRh2 according to the user's specification. it can. Further, since the option discharge unit U6 of the second embodiment is the same as the option discharge unit U6 of the copier U of the first embodiment, the option discharge unit U6 of the copier U and the printer U ′ can be shared. In addition, the image forming apparatus (printer) U ′ according to the second embodiment has the same effects as the image forming apparatus (copier) U according to the first embodiment.

FIG. 24 is an explanatory perspective view of the image forming apparatus according to the third embodiment.
In the description of the third embodiment, components corresponding to those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
The third 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. 24, the printer main body U1 ′ of the printer U ′ as the image forming apparatus of the third embodiment is configured in the same manner as the printer main body U1 ′ of the printer U ′ of the second embodiment, and is disposed on the main body discharge tray TRh. A finisher transfer device U5 similar to the finisher transfer device U5 of the first embodiment is mounted.

(Operation of Example 3)
In the printer U ′ of the third embodiment having the above-described configuration, the finisher transport device U5 similar to that of the copier U of the first embodiment can be mounted, so that the finisher transport device U5 and a finisher (post-processing device) (not shown) are shared. it can. In addition, the printer U ′ of the third embodiment has the same effects as the image forming apparatuses U and U ′ of the first and second embodiments.

FIG. 25 is an explanatory cross-sectional view of a main part of the image forming apparatus according to the fourth embodiment.
FIG. 26 is a perspective explanatory view of the optional discharge unit of the fourth embodiment and corresponds to FIG. 6A of the first embodiment.
In the description of the fourth embodiment, components corresponding to those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
The fourth 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. 25, in the printer U ′ of the fourth embodiment, an option face down tray TRh4 is attached to the rear end of the printer body U1 ′, and an option face down tray TRh5 is attached above the option face down tray TRh4. Above that, an optional face-down tray TRh6 for small size is mounted.

  In FIG. 25, the printer U ′ serving as the image forming apparatus of the fourth embodiment is equipped with three optional discharge units U6 ′ that can be additionally mounted with optional discharge units U6 ′. 25 and 26, 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 option discharge unit U6' of the fourth 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 1a formed at the rear end of the face down side case 1 'is exposed. When the front upper surface cover 112 is removed, the face down side case 1' is removed. The additional mounting front recess 1b formed at the front end is exposed. The additional mounting rear recess 1a is provided with an additional mounting connector U11 'configured similarly to the main body connector U11, a rear option discharge unit positioning hole U16, and a rear option discharge unit lock pin U18. It has been. The additional mounting front recess 1b is provided with a front option discharge unit positioning hole U17 and a front option discharge unit lock pin U19.

  Therefore, the optional discharge unit U6 ′ of the fourth embodiment includes the additional mounting connector U11 ′ disposed on the upper surface of the face-down side case 1 ′, optional discharge unit positioning holes (additional discharge device mounting members) U16 and U17, and options. Corresponding to the discharge unit lock pins (additional discharge device mounting members) U18 and U19, the mounting lock member (additional discharge device mounted member) 16 and the positioning pins (additional discharge device mounted members) 18 and 18 at the lower side It is arranged toward the. The main body side connector U11 of the printer main body U1 ′, the optional discharge unit positioning holes U16 and U17, and the optional discharge unit lock pins U18 and U19 are the mounting lock member 16 of the optional discharge unit U6 ′, the positioning pin 18 when mounting, 18 is provided on the upper end surface. Therefore, the option discharge unit U6 ′ of the fourth embodiment is mounted on the printer body U1 ′ or the option discharge unit U6 ′ from above, unlike the embodiments 1 to 3 which are mounted on the printer body U1 ′ from the left (side). Is done. And it connects electrically with a connector at the time of mounting | wearing.

25 and 26, an additional discharge device mounting portion cover 113 is mounted on the right side of the front-rear central portion of the face-up side case 2 '. When the additional discharge device mounting portion cover 113 is removed, additional discharge is performed. The device mounting portion 114 (see FIG. 25) is exposed.
In FIG. 25, the optional discharge unit U6 ′ according to the fourth embodiment is replaced with the face-up discharge position and the face-down instead of the tray switching gate 54 according to the first embodiment that can move between the face-up discharge position and the face-down discharge position. A tray switching gate 54 ′ that can move between the discharge position and the additional apparatus transfer position is provided.

  The tray switching gate 54 ′ is provided with a pair of solenoids and springs (not shown), and controls the on / off of the pair of solenoids to thereby discharge a sheet to the optional face-up tray TRh 2 (a tray-up discharge position (tray). 25, a position indicated by the uppermost tray switching gate 54 ′ in FIG. 25, and a face-down discharge position for discharging sheets to the optional face-down trays TRh4 and TRh5 (tray discharge position, the second stage from the top in FIG. 25) A position indicated by a tray switching gate 54 ') and an additional apparatus conveying position (shown by the tray switching gate 54' in the third row from the top in FIG. 25) for conveying a sheet to an optional discharge unit U6 'mounted additionally above. Position). The configuration for moving the position of the tray switching gate 54 'by a pair of solenoids and springs is conventionally known (see, for example, Japanese Patent Laid-Open No. 7-315668, etc.), and will not be described in detail.

(Operation of Example 4)
In the printer (image forming apparatus) U ′ of the fourth embodiment having the above-described configuration, an optional discharge unit U6 ′ can be added by sequentially mounting 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 (H06) 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 the first to third embodiments, only one optional discharge unit U6 is mounted. However, a plurality of option discharge units U6 may be mounted side by side in the vertical direction.

(H03) In the fourth embodiment, the tray switching gate 54 'is movable between three positions: a face-up discharge position (tray discharge position), a face-down discharge position (tray discharge position), and an additional apparatus transport position. Although configured, for example, when the face-down tray is not mounted, it is also possible to configure to be movable between two positions, a face-up discharge position (tray discharge position) and an additional apparatus transport position.
(H04) In each of the above embodiments, the common transport path transport roller 60 is provided at the lower end of the optional discharge units (option discharge members) U6, U6 ′. It is also possible to arrange at the upper end of the discharge unit U6 ′.

(H05) In each of the embodiments described above, 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 can also be provided inside the image forming apparatus main body.
(H06) 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 63. 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 63 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.

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 a front view of the image forming apparatus according to the second embodiment. FIG. 23A is a front view in a state where an optional discharge unit is not mounted, and FIG. 23B is a front view in a state where one optional discharge unit is mounted. FIG. 24 is an explanatory perspective view of the image forming apparatus according to the third embodiment. FIG. 25 is an explanatory cross-sectional view of a main part of the image forming apparatus according to the fourth embodiment. FIG. 26 is a perspective explanatory view of the optional discharge unit of the fourth embodiment and corresponds to FIG. 6A of the first embodiment.

Explanation of symbols

1, 1 '... Face down side case,
2, 2 '... Face-up side case,
6 ... Hinge shaft,
20 ... An angle holding member support arm,
28: Face-down discharge member,
47, 49 ... Face-up tray support member,
48: Mounting surface angle holding member,
51. Face-up discharge member,
54 ... Tray switching gate,
54c ... engaging portion when opened,
61 ... Face-down conveyance path,
62 ... Face-up transport path,
63 ... Common transport path,
71a ... Sheet placement surface,
71. Face-up tray body,
72, 73 ... support member engaging portion,
74: Placement surface angle setting unit,
L: Placement surface angle holding link mechanism,
R1 ... main body discharge member,
SN1 ... tray detection sensor,
TRh ... main unit discharge tray,
TRh1, TRh3-TRh5 ... Face down tray,
TRh2 ... Face-up tray,
U1, U1 '... image forming apparatus main body,
U6, U6 '... Optional discharge device.

Claims (6)

An image forming apparatus comprising the following structural requirements (A01) to (A03):
(A01) A main body discharge tray which is provided in the image forming apparatus main body and discharges a sheet on which an image is recorded,
(A02) A main body discharge member for discharging a sheet to the main body discharge tray,
(A03) a face-down discharge member that discharges 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 lower surface;
A face-up discharge member that discharges the sheet to a face-up tray from which the sheet is discharged in a face-up state in which the image recording surface is the upper surface;
A common conveyance path through which a sheet conveyed from the image forming apparatus main body is conveyed;
A face-down conveyance path connected to the common conveyance path and conveying a sheet to the face-down tray;
A face-up conveyance path that is connected to the common conveyance path and conveys a sheet to the face-up tray;
A tray switching gate for conveying the sheet conveyed on the common conveyance path by switching to the face-down conveyance path or the face-up conveyance path;
And an optional discharge device that is detachably mounted above the main body discharge member. The image forming apparatus according to claim 1, further comprising: (A04):
(A04) The tray switching gate movable between a face-up discharge position for discharging a sheet conveyed on the common conveyance path to the face-up tray and a face-down discharge position for discharging a sheet to the face-down tray. . The image forming apparatus according to claim 1, further comprising: (A05) and (A06):
(A05) a face-up tray support member that removably supports the face-up tray;
A tray detection sensor that detects whether or not the face-up tray is mounted in a state where sheets can be discharged;
The optional discharge device,
(A06) The face-up tray having a support member engaging portion that can be engaged with the face-up tray support member. The image forming apparatus according to any one of claims 1 to 3, further comprising the following configuration requirement (A07):
(A07) a face-down case that rotatably supports the face-down discharge member;
A face-up side case that rotatably supports the face-up discharge member;
A hinge shaft connecting the lower end of the face-down side case and the lower end of the face-up side case;
And the upper end portion of the face-up side case and the upper end portion of the face-down side case are capable of opening and closing each other around the hinge axis. The image forming apparatus according to claim 4, comprising the following constituent elements (A08) and (A09):
(A08) a face-up tray main body provided with a sheet placement surface on which the discharged sheet is placed;
A mounting surface angle setting unit formed integrally with the face-up tray body;
The face-up tray having,
(A09) the face-up tray support member supported by the face-up side case;
A mounting surface that is rotatably supported by the face-up tray support member and engages with a mounting surface angle setting unit when the face-up tray is mounted, and holds the sheet mounting surface at a predetermined angle from the horizontal. An angle holding member; and an angle holding member support arm rotatably supported by the face-down side case and rotatably supporting the mounting surface angle holding member. The face-up side case is connected to the face-down side. A mounting surface angle holding link mechanism that holds the angle of the sheet mounting surface at an angle upward from the horizontal before and after opening and closing with respect to the case;
The optional discharge device. The image forming apparatus according to claim 5, comprising the following configuration requirements (A010):
(A010) the tray switching gate supported by the face-up side case;
An opening engagement portion integrally supported by the tray switching gate;
With the face-up side case open to the face-down side case, the gate position holding engagement that engages with the opening engaging portion to hold the tray switching gate at the face-up discharge position. The mounting surface angle holding link mechanism described above having a portion;
The optional discharge device.

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