Image forming apparatus that only prompts an inspection request after a predetermined number of failures of a rotary guide member

An image forming apparatus has a rotary guide including a path for a sheet being conveyed. The guide is rotatable so that an exit of the path faces one of at least two conveyance destinations. A motor rotates the guide, and a detector outputs a detection signal when a predetermined posture of the guide is detected. An instructing section outputs instruction signals to the motor to rotate the guide toward the predetermined posture. A judging section judges whether a detection signal has been received in response to the instruction signal, and a notifying section counts a consecutive occurrence number of a judgment result to the effect that no detection signal was received in response to the instruction signal this time and gives a notification prompting an inspection request of the image forming apparatus when the consecutive occurrence number reaches a set number.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image forming apparatus provided with a sheet conveying direction switching mechanism for switching a conveying direction of a sheet being conveyed.

2. Description of the Related Art

Conventionally, there has been known a sheet conveying direction switching device used in a sheet conveyor system of an image forming apparatus. For example, a device for switching a conveyance destination of a sheet having a toner image formed on a surface upon the completion of an image forming process between a discharge tray and a switchback conveyance path for a two-sided printing process is known as such a sheet conveying direction switching device. Such a sheet conveying direction switching device includes a rotary guide member disposed at a diverging point to discharge destinations for switching the conveyance destination of the sheet.

This rotary guide member is composed of a pair of circular side plates arranged to face at a distance slightly longer than the width of the sheet, four guide plates extending between these circular side plates and rotary shafts each projecting from the corresponding circular side plate. The rotary guide member is rotatable about the rotary shafts. Different guide paths (straight guide path in the center and reversing guide paths at the opposite sides) are defined between the respective guide plates. Which of the guide paths the sheet conveyed to the rotary guide member passes is determined based on a rotation amount from a reference phase (rotational position as a reference) of the rotary guide member. According to the guide path along which the sheet passes, the sheet is discharged to the preset conveyance destination.

Such a rotary guide member is driven and rotated about the rotary shafts by a stepping motor which is driven and rotated according to a pulse number of a pulse signal. In this way, the posture of the rotary guide member is set (i.e. the conveyance destination of the sheet being conveyed is set).

The stepping motor rotates only by an angle corresponding to the pulse number of the pulse signal from the present position. Thus, the rotary guide member is first set in a preset reference posture and, in this state where the rotary guide member is set in the reference posture, the stepping motor is rotated, for example, by a pulse signal having a pulse number corresponding to the discharge tray or by a pulse signal having a pulse number corresponding to a switchback conveyance path, whereby the rotary guide member can be set (positioned) in the reference posture (rotational position) determined beforehand according to the conveyance destination. Thus, the image forming apparatus of this type normally includes a reference posture detection sensor for detecting that the rotary guide member has reached the reference posture in order to position the rotary guide member in the reference posture.

On the other hand, there has been conventionally provided no means (sensor) for directly detecting an abnormality of the motor for driving the rotary guide member. Thus, an abnormality is indirectly judged to have occurred in the motor if the rotary guide member was not rotated and no detection signal was output from the reference posture detection sensor even through an instruction was given to drive and rotate the rotary guide member.

In this way, the abnormality of the motor was judged when the rotary guide member was not rotated. Thus, an abnormally was judged to have occurred in the stepping motor and a notification was given to inform the abnormality of the stepping motor and prompt an inspection request to a service person not only when the abnormality occurred in the stepping motor itself, but also when the rotation of the rotary guide member was hindered, for example, by a mere sheet jam.

However, there are causes of abnormalities that can be dealt with by a user himself without requiring the service person to inspect. One example is a case where the rotation of the rotary guide member is hindered by a sheet jam. If the user contacts the service person and lets him to deal with a problem although this problem can be dealt with by the user himself, it increases burdens on a party in charge of apparatus maintenance and is not also preferable to the user since the user cannot use the image forming apparatus until a problem solving operation by the service person is completed.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an image forming apparatus capable of maximally reducing the number of operations by a service person upon the occurrence of a problem that no detection signal is output from a reference posture detection sensor for detecting that a rotary guide member has reached a reference posture (has been positioned at a reference position).

One aspect of the present invention is directed to an image forming apparatus, comprising a rotary guide member including a guide path capable of permitting the passage of a sheet being conveyed and rotatable about a supporting shaft extending in a direction orthogonal to a conveying direction to change the posture thereof in such a manner that the exit of the guide path faces toward any one of at least two conveyance destinations; a motor for changing the posture of the rotary guide member; a detector for outputting a detection signal when a predetermined posture of the rotary guide member is detected; an instructing section for outputting an instruction signal to the motor to operate the rotary guide member toward the predetermined posture when a predetermined operation which triggers the start of a process for confirming the operation of the rotary guide member using the detector is performed to the image forming apparatus; a judging section for judging whether or not the detection signal has been received from the detector in response to the instruction signal by the instructing section this time; and a notifying section for counting a consecutive occurrence number of a judgment result to the effect that no detection signal was received in response to the instruction signal this time when the judging section judged that no detection signal was received in response to the instruction signal this time and giving at least one of a notification prompting an inspection request of the image forming apparatus and a notification relating to prompting of the inspection request when the consecutive occurrence number reaches a set plural number.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, one embodiment of an image forming apparatus according to the present invention is described with reference to the drawings. In the respective drawings, constructions identified by the same reference numerals are the same constructions and not repeatedly described.FIG. 1is a front view in section showing an exemplary construction of an image forming apparatus10according to the present invention, andFIG. 2is an enlarged diagram showing a conveying direction switching portion109as a mechanical part of a conveying direction switching device20shown inFIG. 1and its periphery. The conveying direction switching portion109is formed in an apparatus main body11of the image forming apparatus10. InFIGS. 1 and 2, X-X directions are referred to as lateral directions, particularly −X direction being a leftward direction and +X direction being a rightward direction.

The image forming apparatus10shown inFIG. 1is a copier of the so-called internal discharge type and provided with the apparatus main body11, an image forming unit12, a fixing unit13, a sheet storing unit14, a discharge unit15, an image reading unit16and an operation unit17. A part (internal discharge tray151to be described later) of the discharge unit15is formed by denting a part of the apparatus main body11below the image reading unit16. Thus, this image forming apparatus10is called to be of the internal discharge type.

The apparatus main body11includes a lower main body111having a rectangular parallelepipedic outer shape, an upper main body112having a flat rectangular parallelepipedic outer shape arranged to face the lower main body111from above, and a connecting part113disposed between these upper main body112and lower main body111. The connecting part113is a structure for connecting the lower and upper main bodies111,112with each other with the internal discharge tray151of the discharge unit15formed between the lower and upper main bodies111,112.

The image forming unit12, the fixing unit13and the sheet storing unit14are housed in the lower main body111, and the image reading unit16is mounted in the upper main body112. The operation unit17is provided on a front edge part of the upper main body112.

The operation unit17is for receiving operation inputs relating to an image forming process and includes a numerical pad used to input the number of sheets P to be processed, various operation keys171, a touch panel172including an LCD (Liquid Crystal Display) used for touch input, a power button173used to turn on and off power supply required by the respective parts of the image forming apparatus1, etc.

The operation unit17also receives type information of sheets P indicating whether the sheets P stored in or on sheet storage units such as the sheet storing unit14and a manual feed tray18are ordinary sheets, thick sheets or transparent resin sheets such as those for OHP (OverHead Projector). In the following description, sheet members other than paper sheets such as OHP sheets are also written as sheets P.

The sheet storing unit14includes sheet cassettes141detachably insertable at positions right below the image forming unit12in the lower main body111and large capacity decks142detachably insertable at a position below the sheet cassettes141and capable of storing a large number of sheets P. In this embodiment, two sheet cassettes141are arranged one above the other and two large capacity decks142are arranged side by side.

Upon performing the image forming process, sheets P are dispensed one by one from a sheet stack P1stored in the sheet cassette141or large capacity deck142and fed to the image forming unit12to have the image forming process (printing process) performed thereto.

The discharge unit15includes the internal discharge tray (first discharge tray; switchback tray)151formed between the lower and upper main bodies111,112, an external discharge tray (second discharge tray)152formed outside the apparatus main body11and an internal finisher153provided at a position right above the internal discharge tray151. A sheet having a toner image already transferred thereto and conveyed from the image forming unit12to the conveying direction switching portion109provided in the connecting part113via the fixing unit13is discharged to any one of the internal discharge tray151, the external discharge tray152and the internal finisher153set as discharge destinations beforehand by the conveying direction switching portion109. The internal finisher153is for performing post-processing such as punching or stapling to the discharged sheets P.

The internal discharge tray151is also used as a switchback tray (switchback portion) for turning sheets P, one side of each of which is completed with the printing process, upside down to perform the printing process also to the other side upon performing a two-sided printing process to the sheet P in addition to being simply used to discharge sheets P. In other words, the sheets P each completed with the printing process on one side thereof are switched back with the last one in the lead and returned to the image forming unit12after being temporarily discharged to the internal discharge tray151. The sheets P completed with one-sided printing have the printing process performed to the other sides in the image forming unit12and are discharged to the internal discharge tray151or the external discharge tray152.

The image reading unit16includes a contact glass161mounted in an upper opening of the upper main body112and used to place a document, an openable and closable document pressing cover162for pressing the document placed on the contact glass161, an automatic document reader163mounted in the document pressing cover162and a scanning mechanism164for scanning an image of the document placed on the contact glass161.

An image of a document placed on the contact glass161or fed onto the contact glass161by the automatic document feeder163is converted into a digital signal and output to an exposure unit123to be described later for the image forming process after being read as analog information by the scanning mechanism164.

The manual feed tray18is provided at a position right above the sheet storing unit14on the right surface of the lower main body111. This manual feed tray18has its bottom part supported rotatably about a supporting shaft181and is displaceable between a closing posture in which it stands to close a manual feed port and an opening posture in which it projects rightward. With such a manual feed tray18set in the opening posture, sheets P are manually fed one by one. The sheets P manually fed from such a manual feed tray18are fed toward a nip between a photoconductive drum121and a transfer roller125to be described later via a vertical sheet conveyance path101(main conveyance path).

An openable and closable maintenance door19(opening door) is provided on the left surface of the lower main body111. The external discharge tray152is provided at a position above this maintenance door19. A sheet P completed with the printing process in the image forming unit12is selectively discharged to either one of this external discharge tray152and the internal discharge tray151.

The photoconductive drum121is arranged at a left position in a substantially vertical middle part of the image forming unit12. This photoconductive drum121is rotated clockwise about a drum center. The photoconductive drum121has the circumferential surface thereof uniformly charged by a charger unit122arranged immediately to the right while being rotated.

The exposure unit123for irradiating the circumferential surface of the photoconductive drum121with a laser beam based on image information of a document image read by the image reading unit16is arranged to the right of the photoconductive drum121. An electrostatic latent image is formed on the circumferential surface of the photoconductive drum121by the irradiation of the laser beam from this exposure unit123. Toner is supplied toward this electrostatic latent image from a developing unit124arranged below the photoconductive drum121, whereby a toner image in conformity with the electrostatic latent image is formed on the circumferential surface of the photoconductive drum121.

A sheet P is conveyed upward from the sheet cassette141or the large capacity deck142along the vertically extending vertical sheet conveyance path101to be fed to the photoconductive drum121having a toner image formed thereon via a pair of registration rollers143for adjusting timing. The sheet P having reached the photoconductive drum121has the toner image on the circumferential surface of the photoconductive drum121transferred thereto by the action of the transfer roller125arranged to the left of the photoconductive drum121and facing the photoconductive drum121. The sheet P having the toner image transferred thereto is separated from the photoconductive drum121and conveyed to the fixing unit13.

The photoconductive drum121completed with a process of transferring the toner image to the sheet P continues to be rotated clockwise, whereby the circumferential surface thereof is cleaned by a cleaning device126arranged right above the photoconductive drum121and heads for the charging unit122for the next image forming process.

The fixing unit13includes a heating roller131internally provided with a heating element such as a halogen lamp, a fixing roller132arranged at the left side and facing the heating roller131, a fixing belt133mounted between the fixing roller132and the heating roller131and a pressure roller134arranged at the left side and facing the outer surface of the fixing belt133. The sheet P conveyed from the image forming unit12to the fixing unit13receives heat of the heating roller131via the fixing belt133while passing a nip between the fixing belt133and the pressure roller134, whereby the toner image is fixed to the sheet P.

The sheet P after the fixing process has the conveyance destination thereof switched by the conveying direction switching portion109above the fixing unit13to be discharged to the external discharge tray152via a discharge conveyance path102(second auxiliary conveyance path) or to the internal discharge tray151via a reciprocating conveyance path103(first auxiliary conveyance path) when the sheet P is for one-sided printing, and is temporarily discharged to the internal discharge tray151(switchback portion), which doubles as a switchback tray, via the reciprocating conveyance path103(third auxiliary conveyance path) for two-sided printing.

In the case of two-sided printing, the sheet P completed with the printing process on one side has the front half thereof discharged to the internal discharge tray151via the reciprocating conveyance path103. Then, this sheet P is conveyed in a reverse direction via a vertically extending reversing conveyance path104provided in the maintenance door19and fed to the image forming unit12again to have the printing process performed to the other side while being turned upside down. The sheet P completed with two-sided printing is discharged to the internal discharge tray151or the external discharge tray152.

The maintenance door19includes a cover member191which is provided immediately to the right of the reversing conveyance path104and the right surface of which faces the left surface of the image forming unit12. This cover member191is mounted on the right surface of the maintenance door19. With the maintenance door19closed, a part of the vertical sheet conveyance path101for conveying sheets P fed from the sheet cassettes141, the large capacity decks142and also the manual feed tray18is formed between the right surface of the cover member191and the left surface of the image forming unit12.

As shown inFIG. 2, the conveying direction switching portion109is set in a space right above a housing135of the fixing unit13and to the left of a left wall151aof the internal discharge tray151. A first arcuate guide plate108ahaving a curved surface concave downward and extending into the internal discharge tray151beyond the upper edge of the left wall151aof the internal discharge tray151is disposed to the right and above the conveying direction switching portion109. Further, a second arcuate guide plate108bconcave downward to convey the sheet P toward the revering conveyance path104located below at the left side of the fixing unit13is disposed to the left and above the conveying direction switching portion109.

Between the left end of the first arcuate guide plate108aand the right end of the second arcuate guide plate108b, a clearance is formed to receive the sheet P discharged upward from the fixing unit13via the conveying direction switching portion109. An upper-end conveyance path101aas a part of the vertically extending vertical sheet conveyance path101is formed above this clearance.

A switching guide member107having a substantially isosceles triangular shape is disposed right above this upper-end conveyance path101a. This switching guide member107is for switching the discharge destination of the sheet P fed from the upper-end conveyance path101abetween the internal finisher153and the external discharge tray152and is so postured that a part corresponding to a vertex of the isosceles triangular shape faces downward.

Such a switching guide member107is displaceable between a finisher posture for guiding the sheet P to the internal finisher153along the right surface by being rotated clockwise about a guide shaft107asupporting the switching guide member107substantially at a center-of-gravity position and an external-discharge-tray posture for guiding the sheet P to the external discharge tray152along the left surface by being rotated counterclockwise about the guide shaft107a.

In other words, sheets completed with the image forming process in the image forming unit12and the fixing process in the fixing unit13are discharged to the respective discharge destinations according to the purpose after being temporarily guided to the conveying direction switching portion109. The conveying direction switching portion109includes a rotary guide member30instead of a conventional triangular switching guide.

A plurality of conveyor rollers are arranged around this rotary guide member30, and a sheet P is smoothly taken in and out of the rotary guide member30by these conveyor rollers. Such conveyor rollers include fixing-unit exit rollers106aarranged at an exit position of the fixing unit13and right before (right below) the rotary guide member30, first discharge rollers106barranged below the first arcuate guide plate108a(i.e. in the reciprocating conveyance path103) and right before the internal discharge tray151for discharging the sheet P to the internal discharge tray151, reversing-conveyance-path conveyor rollers106carranged below the second arcuate guide plate108bfor conveying the sheet toward the reversing conveyance path104, switching-guide-member conveyor rollers106darranged right below the switching guide member107at the downstream end of the upper-end conveyance path101afor conveying the sheet P toward the switching guide member107, second discharge rollers106earranged at the upstream end of the external discharge tray152and third discharge rollers106farranged at the entrance of the internal finisher153.

Various sheet sensors are arranged around the rotary guide member30to detect a state of conveyance of the sheet P via the rotary guide member30. Such sheet sensors include a fixing sensor105a(leading end take-in timing obtaining portion) arranged at the downstream end of the fixing unit13(on the upper part of the housing of the fixing unit13), a first discharge sensor105bdisposed at the entrance of the internal discharge tray151, a reverse-feed sensor105cdisposed at an upstream end position of the reversing conveyance path104, a second discharge sensor105darranged near the second discharge rollers106eat the upstream end of the external discharge tray152and a third discharge sensor105earranged near the third discharge rollers106fat the entrance of the internal finisher153.

The sheet P fed from the fixing unit13is conveyed toward a specified position by the detection of the sheet P by these sensors and preset operations of the conveying direction switching portion109and the switching guide member107based on these detection results.

The conveying direction switching portion109is described below with reference toFIGS. 3 to 5.FIGS. 3 and 4are perspective views partly cut away showing one embodiment of the conveying direction switching portion109, whereinFIG. 3shows a state viewed obliquely from above, i.e. viewed from an exit side for the sheet P andFIG. 4shows a state viewed obliquely from below, i.e. viewed from an entrance side for the sheet P.FIG. 5is a section along V-V of the conveying direction switching portion109shown inFIG. 3. InFIG. 5, a state where the rotary guide member30is set in a reference posture S1(reference rotational position) is shown by chain double-dashed line and a state where the rotary guide member30is set in a standing posture S2is shown by solid line. InFIGS. 3 to 5, X directions and Y directions are referred to as lateral directions and forward and backward directions and, particularly, −X, +X, −Y and +Y directions are respectively referred to as leftward, rightward, forward and backward directions.

First, as shown inFIG. 3, the conveying direction switching portion109includes the rotary guide member30for receiving a sheet P fed from the fixing unit13(FIG. 2) via the fixing-unit exit rollers106aand guiding this sheet P to be discharged to a specified position set beforehand, guide pulleys40attached to this rotary guide member30for guiding the sheet P in such a manner as not to adversely affect a toner image formed on the sheet P, a posture changer50for changing the posture of the rotary guide member30by rotating the rotary guide member30in forward and reverse directions about specified guide shafts (supporting shaft)34, and a reference position detector60for detecting that the rotary guide member30is located at the reference rotational position.

The rotary guide member30includes a pair of side plates31facing in forward and backward directions, a pair of arcuate guide plates32mounted between the respective side plates31and facing in lateral directions, a plurality of guide fins33fixed to the left arcuate guide plate32while being arranged side by side to face in forward and backward directions, a pair of front and rear guide shafts34projecting concentrically in opposite directions from substantially center-of-gravity positions of the front and rear side plates31, and a cover body35mounted between the upper edges of the pair of side plates31.

Each side plate31is formed by setting a substantially square basic shape when viewed from front and then deforming some parts of the square shape. By mounting the left and right arcuate guide plates32between this pair of side plates31, the pair of arcuate guide plates32function as structural members and the rotary guide member30is formed to be structurally strong.

The pair of arcuate guide plates32are so formed that facing surfaces arcuately bulge out in opposite directions when viewed from front. Such a pair of arcuate guide plates32are so set that an interval (lateral distance) between them is widest at their bottom ends and gradually reduced toward the upper ends. A guide path320for guiding the sheet P fed from the fixing unit13is formed between the arcuate guide plates32.

In other words, the pair of arcuate guide plates32are arranged to face at a distance and form one guide path320for guiding the sheet P fed from the fixing unit13. The arcuate guide plates32include arcuate surfaces extending in an extending direction of this guide path320. As a result of including such arcuate surfaces, the distance between the arcuate guide plates32is wide between the bottom edges and gradually reduced toward the upper ends when viewed from front.

The interval between the bottom edges (bottom end opening side) of the pair of arcuate guide plates32serves as a receiving opening321(entrance) for receiving the sheet P discharged from the fixing unit13and the interval between the upper edges (upper end opening side) serves as a discharge opening322(exit) for discharging the sheet P. The sheet P discharged from the fixing unit13is introduced to between the pair of arcuate guide plates32from the receiving opening321via a detection position of the fixing sensor105aand discharged upward via the discharge opening322and a later-described discharge port351(exit) formed in the cover body35. The destination of the sheet P discharged from the discharge port351through the guide path320of the rotary guide member30is predetermined depending on the posture of the rotary guide member30. This is described in detail later.

The guide fins33receive and guide the sheet P being conveyed toward the reversing conveyance path104from the internal discharge tray151where the sheet P was temporarily stored with the rotary guide member30set in a reversing-conveyance-path posture S4(seeFIG. 7B) to be described later. At this time, the sheet P is the one for two-sided printing, to the other side of which the printing process should be performed. The upper end surfaces (guide surfaces) of such guide fins33are formed to have arcuate shapes convex upward similar to the upper end surfaces of the side plates31with the rotary guide member30set n the reversing-conveyance-path posture S4(FIG. 7B). Accordingly, in the reversing-conveyance-path posture S4, an upstream end part (third auxiliary conveyance path) of the reversing conveyance path104is formed by the upper end surfaces of the guide fins33and the second arcuate guide plate108bcurved downwardly.

The pair of guide shafts34projecting concentrically in opposite directions from the pair of side plates31are supported on an unillustrated frame of the apparatus main body11. By the driving of the posture changer50, the rotary guide member30can be integrally rotated in forward and reverse directions about the centers of the guide shafts34.

The cover body35is for preventing the entrance of foreign matters such as dust into the rotary guide member30, covers an upper part of the rotary guide member30as shown inFIG. 3and is mounted between the upper edges of the pair of side plates31inFIG. 3. At a top part of such a cover body35, the discharge port351(exit) extending in forward and backward directions for the discharge of the sheet P is formed at a position facing the discharge opening322of the pair of arcuate guide plates32.

A plurality of pairs of guide pulleys40are arranged one behind another with the pair of left and right arcuate guide plates32located between each pair. A pair of guide pulleys40are supported rotatably about a pair of left and right pulley shafts41. The pair of pulley shafts41are mounted between the pair of side plates31at laterally outer positions of the left and right arcuate guide plates32while penetrating through the respective guide fins33(only left pulley shaft41).

On the other hand, the left and right arcuate guide plates32are formed with through windows323as shown inFIG. 4at positions corresponding to the respective guide pulleys40. The respective guide pulleys40enter the guide path320between the pair of arcuate guide plates32through these through windows323. In this way, the circumferential surfaces of each pair of guide pulleys40partly project into the guide path320and face each other.

Accordingly, the sheet P discharged from the fixing unit13passes between the circumferential surfaces of the left and right guide pulleys40without the image forming surface of the sheet P coming into contact with the pair of arcuate guide plates32while being introduced to between the pair of arcuate guide plates32via the receiving opening321. At this time, even if the image forming surface of the sheet P should come into contact with the circumferential surfaces of the guide pulleys40, the guide pulleys40are rotated about the pulley shafts41by this contact, wherefore the image forming surface of the sheet P does not come into sliding contact with the inner surfaces of the arcuate guide plates32. Thus, the occurrence of problems such as an image disturbance caused by the sliding contact of the image forming surface of the sheet P can be effectively prevented.

The posture changer50is for setting the posture of the rotary guide member30in accordance with a control signal from a controller200to be described later. Such a posture changer50includes a stepping motor51, a drive gear52concentrically and integrally rotatably fitted on a drive shaft511of the stepping motor51, and a section gear53integrally rotatably fixed to the rear guide shaft34and engaged with the drive gear52.

Since the stepping motor51is so constructed as to set an angle of rotation according to a pulse number of a pulse signal, the angle of rotation of the stepping motor51, i.e. the posture of the rotary guide member30is highly accurately controlled by supplying a signal having a preset pulse number to the stepping motor30according to purpose.

Accordingly, in the case of using the stepping motor51, the posture can be highly accurately changed and, in addition, there is no such inconvenience of generating abnormal noise as compared with the case where a guiding destination is changed by changing the posture of a specified guiding member by turning on and off power supply, for example, to a solenoid as in the prior art.

Such a stepping motor51is horizontally installed at a rear upper part of the rotary guide member30so that the drive shaft511extends forward. A drive force of the stepping motor51is transmitted to the rotary guide member30via the drive gear52and the section gear53. Thus, the rotary guide member30is rotated in forward and reverse directions about the guide shafts34to change its posture by the stepping motor51being driven in forward and reverse directions.

The reference position detector60includes a light blocking piece61projecting radially outward from the section gear53and an optical sensor62arranged on a rotational path of the light blocking piece61about the guide shaft34to face the light blocking piece61with the rotary guide member30set in the reference posture S1(FIG. 6A) as a home position.

The optical sensor62is a so-called photointerrupter constructed such that a light emitting element623and a light receiving element624are arranged to face each other in a forked supporting case621including a pair of element supporting arms622.

The supporting case621is so positioned that the respective element supporting arms622are located at the opposite sides of the rotational path of the light blocking piece61and the light blocking piece61is located between the pair of element supporting arms622with the rotary guide member30set in the reference posture S1. The light emitting element623is provided in one element supporting arm622and the light receiving element624is so provided in the other element supporting arm622as to face the light emitting element623. The reference posture S1is an example of a predetermined posture.

Accordingly, unless the rotary guide member30is set in the reference posture S1, light emitted from the light emitting element623is received by the light receiving element624to turn the light receiving element624on. In this way, it can be detected that the rotary guide member30is not set in the reference posture S1.

On the contrary, if the rotary guide member30is set in the reference posture S1, the light blocking piece61is located between the pair of element supporting arms622and light from the light emitting element623is blocked by the light blocking piece61, wherefore the light receiving element624is turned off. In this way, it can be detected that the rotary guide member30is set in the reference posture S1.

In other words, a signal indicating an off-state of the light receiving element624serves as a detection signal indicating that the rotary guide member30is located in the reference posture S1(reference rotational position). The detection signal indicating that the rotary guide member30is located in the reference posture S1(reference rotational position) is merely called as a detection signal below.

With a rotational position of the stepping motor51when the light receiving element624is turned off set as the reference rotational position, excitation pulses are supplied to the stepping motor51from this reference rotational position on, whereby the stepping motor51is rotated by a desired angle of rotation according to the number of the excitation pulses to set the rotary guide member30in a desired posture.

For example, the reference posture S1is located at a furthest counterclockwise position out of the reference posture S1(reference rotational position), the standing posture S2, the internal-discharge-tray posture S3and the reversing-conveyance-path posture S4to be described later. Accordingly, regardless of in which posture the rotary guide member30is set, the rotary guide member30is rotated to reach the reference posture S1(reference rotational position) and turn the light receiving element624off if an instructing section202to be described later continues to output excitation pulses as an instruction signal to rotate the stepping motor51in such a direction as to rotate the rotary guide member30counterclockwise (direction toward the reference posture S1).

The instructing section202can set the rotary guide member30in the reference posture S1by stopping the output of the excitation pulses when the light receiving element624is turned off.

Sheet guiding postures of the rotary guide member30are described below with reference toFIGS. 6 and 7.FIGS. 6 and 7are front views in section of the rotary guide member30showing the sheet guiding postures of the rotary guide member30.FIG. 6Ashows a state where the rotary guide member is set in the reference posture S1andFIG. 6Bshows a state where the rotary guide member30is set in the standing posture S2.

FIG. 7Ashows a state where the rotary guide member30is set in the internal-discharge-tray posture S3andFIG. 7Bshows a state where the rotary guide member30is set in the reversing-conveyance-path posture S4. It should be noted that direction indication by X inFIGS. 6 and 7is as inFIG. 1(−X: leftward, +X: rightward).

First of all, when the rotary guide member30is set in the reference posture S1as shown inFIG. 6A, the guide path320between the pair of arcuate guide plates32is rotated counterclockwise by about 30° about the guide shafts34from a vertical position, thereby being inclined toward the left.

In this state, the light blocking piece61fixed to the section gear53is located between the pair of element supporting arms622of the optical sensor62to block light from the light emitting element623(FIG. 3) so that no light is incident on the light receiving element624. In this way, it is detected that the rotary guide member30is set in the reference posture S1and the reference position of the stepping motor51is detected.

Further, when the rotary guide member30is set in the standing position S2as shown inFIG. 6B, the discharge port351is so positioned as to face toward the upper-end conveyance path101a. In the standing posture S2, a sheet P discharged from the fixing unit13is introduced into the guide path320of the rotary guide member30from the receiving opening321via the detection position of the fixing sensor105a, passes between the pairs of guide pulleys40and is discharged upward toward the upper-end conveyance path101afrom the discharge port351.

Thereafter, the sheet P is directly discharged to the external discharge tray152or discharged to the external discharge tray152as one of a sheet bundle after being temporarily discharged to the internal finisher153and post-processing such as stapling is applied.

When the rotary guide member30is set in the internal-discharge-tray posture S3as shown inFIG. 7A, the discharge port351is so positioned as to face the discharge rollers106b. In the internal-discharge-tray posture S3, the sheet P discharged from the fixing unit13passes along the guide path320of the rotary guide member30and is discharged to the internal discharge tray151while being guided by the first arcuate guide plate108aafter exiting from the discharge port351. The internal-discharge-tray posture S3is also used for switching the sheet P back to turn the sheet P upside down in the case of performing two-sided printing to the sheet P.

When the rotary guide member30is set in the reversing-conveyance-path posture S4as shown inFIG. 7B, the guide fins33are arranged to extend between the first discharge rollers106band the reversing conveyance path104. In this way, the sheet P conveyed in the reverse direction by the first discharge rollers106bfrom the internal discharge tray151upon the switchback at the time of two-sided printing can be conveyed to the reversing conveyance path104by being guided by the guide fines33.

FIG. 8is a block diagram showing an exemplary electrical construction of the image forming apparatus10shown inFIG. 1. The image forming apparatus10includes the controller200in addition to the above mechanical parts. InFIG. 8, various rollers, switching guides, etc. for conveying sheets are collectively shown as a conveying mechanism120.

The controller200includes a CPU (Central Processing Unit) for executing, for example, specified arithmetic processings, a ROM (Read Only Memory) storing a specified control program, a RAM (Random Access Memory) for temporarily storing data, a timer circuit, and peripheral circuits of these. The image reading unit16, the image forming unit12, the fixing unit13, the conveying mechanism120and the operation unit17are connected to the controller200.

Various sensors such as the optical sensor62and the fixing sensor105aare also connected to the controller200. Further, the stepping motor51is connected to the controller200. The controller200functions as a copy controlling section201, the instructing section202, a judging section203and a notification processing section204(notifying section), for example, by executing the control program stored in the ROM.

The fixing sensor105ais in the form of a lever. When a sheet P is discharged from the fixing unit13by the fixing-unit exit rollers106a, the fixing sensor105ais pushed up by the sheet P to be turned on, thereby detecting the sheet P. When the sheet P is further conveyed and the trailing end thereof passes beyond the position of the fixing sensor105a, the fixing sensor105areturns to its initial position to be turned off.

In this way, the fixing sensor105ais turned on while the sheet P is present at the position of the fixing sensor105a, i.e. while the sheet P discharged from the fixing unit13is passing the position leading to the receiving opening321of the guide path320. Accordingly, a turn-on timing of the fixing sensor105aindicates an entrance timing of the leading end of the sheet P into the receiving opening321and a turn-off timing of the fixing sensor105aindicates an entrance timing of the trailing end of the sheet P into the receiving opening321.

The fixing sensor105ais not necessary a lever-type sensor and may be a sheet sensor using, for example, an optical sensor or an electrostatic sensor.

The copy controlling section201controls the operations of the respective parts in the apparatus to copy a document image. Specifically, the copy controlling section201causes the conveying mechanism120to convey a sheet P and transmits an image data read from a document by the image reading unit16to the image forming unit12, thereby causing the image forming unit12to form an image on the sheet P.

The instructing section202is for instructing the respective parts of the image forming apparatus10to perform a warm-up operation when the maintenance door19is closed. The warm-up operation includes, for example, heating-up of the fixing roller and various units and the rotation of the photoconductive drum121. The instructing section202outputs an instruction signal indicating an instruction to execute the warm-up operation and an instruction to confirm the operation of the rotary guide member30to the stepping motor51.

Specifically, the instructing section202continues to output excitation pulses as the instruction signal for rotating the rotary guide member30in the counterclockwise direction, thereby rotating the stepping motor51to drive and rotate the rotary guide member30. Upon receiving a detection signal from the reference position detector60, the instructing section202stops outputting the instruction signal, thereby causing the rotary guide member30to be positioned in the reference posture S1(reference rotational position).

In this way, the rotary guide member30is set in the reference posture S1when the warm-up operation is completed.

The judging section203is for judging whether or not a detection signal indicating that the rotary guide member30is in the reference posture S1(reference rotational position) has been received in response to the instruction signal output to the stepping motor51by the instructing section202this time.

The notification processing section204counts a consecutive occurrence number of a judgment result to the effect that no detection signal was output in response to the instruction signal this time if the judging section203judged that no detection signal was received in response to the instruction signal by the instructing section202this time. The notification processing section204judges whether or not this count value has reached, for example, “3” as a preset number and, for example, causes the LCD to visually notify the occurrence of a sheet jam, assuming that the detection signal output from the instructing section202this time was not received due to the sheet jam if the count value has not reached “3”.

Presumable sheet jams include a sheet jam which occurs upon the collision of the leading end of a sheet P with the arcuate guide plate32due to a curved state of the sheet P beyond a presumable range, for example, when the sheet P from the fixing unit13is guided to the guide path320and a sheet jam which occurs upon the collision of the leading end of a sheet with the frame or the like in the apparatus due to a curved state of the sheet beyond a presumable range during the conveyance of the sheet discharged from the discharge opening322of the rotary guide member30toward the switching-guide-member conveyor rollers106d. If such a sheet jam occurs, the rotation of the rotary guide member30is hindered.

On the other hand, the notification processing section204causes the LCD to visually notify the occurrence of an abnormality in the stepping motor51and prompt an inspection request of the image forming apparatus10to a service person. The form of notification is not limited to the visual one, and an auditory notification using, for example, a loudspeaker can also be adopted.

Next, a series of notification operations of the image forming apparatus10constructed as described above are described.FIG. 9is a flow chart showing an exemplary operation of the image forming apparatus10shown inFIG. 1.

First of all, as shown inFIG. 9, when the controller200detects that the opened maintenance door was closed (YES in Step #1), the instructing section202instructs the respective parts in the image forming apparatus10to start the warm-up operation and outputs an instruction signal indicating an instruction to confirm the operation of the rotary guide member30, i.e. an instruction signal for rotating the rotary guide member30toward the reference posture S1, to the stepping motor51(Step #2).

Subsequently, the judging section203judges whether or not a detection signal indicating that the rotary guide member30has reached the reference rotational position has been received from the reference posture detector60within a preset judgment period after the start of the output of the instruction signal to the stepping motor51by the instructing section202(Step #3), and the controller200sets the image forming apparatus10in a standby state (Step #7) after the warm-up operation is completed if the detection signal is judged to have been received within the judgment period (YES in Step #3).

For example, a period necessary to rotate the rotary guide member30from the reversing-conveyance-path posture S4most distant from the reference posture S1(largest rotation amount) out of the postures, which the rotary guide member30can take, to the reference posture S1by rotating the stepping motor51in accordance with the instruction signal is set as the judgment period.

Further, the judging section203initializes the count value of the consecutive occurrence number to be described later to zero in Step #7.

On the other hand, the judging section203counts the consecutive occurrence number of the judgment result to the effect that no detection signal was received in response to the instruction signal this time when judging that no detection signal was received from the reference posture detector60within the judgment period, and judges based on the count value of the consecutive occurrence number whether or not the judgment result this time to the effect that no detection signal was received in response to the instruction signal this time is the first or second one (Step #4).

At this time, if the stepping motor51is rotated in accordance with the instruction signal output from the instructing section202even once and the detection signal was output from the reference posture detector60within the judgment period, the count value of the consecutive occurrence number is initialized to zero in Step #7. Thus, if the count value of the consecutive occurrence number is 2 or larger, it means the consecutive occurrence of an event where no detection signal indicating the presence at the reference rotational position within the judgment period was obtained even though the instructing section202output the instruction signal.

If the judging section203judges that the judgment result this time is the first or second one (YES in Step #4), the notification processing section204causes, for example, the LCD to visually notify the occurrence of a sheet jam (Step #5). On the other hand, if the judging section203judges that the judgment result this time is neither the first nor the second one, i.e. if the judgment result this time is the third or later one (NO in Step #4), the notification processing section204causes, for example, the LCD to visually notify the occurrence of an abnormality in the stepping motor51and a message prompting an inspection request of the image forming apparatus10to the service person (Step #6).

The message prompting the inspection request of the image forming apparatus10is, for example, a message saying that “Abnormality occurred in stepping motor51. Contact a service person to request an inspection”.

As described above, in this embodiment, when the maintenance door19is closed, an instruction signal for locating the rotary guide member30at the reference rotational position is output to the stepping motor51. If no detection signal was received from the reference posture detector60within the judgment period after the start of the output of the instruction signal to the stepping motor51, the consecutive occurrence number of the judgment result to the effect that no detection signal was received in response to the instruction signal this time was counted. If the judgment result is the first or second one, the notification processing section204notifies the occurrence of a sheet jam. On the other hand, if the judgment result is the third or later one, the notification processing section204notifies the occurrence of an abnormality in the stepping motor51and prompts the inspection request of the image forming apparatus10to the service person.

In this way, a user is let to deal with abnormalities and inspection requests of the image forming apparatus10to the service person are avoided until the consecutive occurrence number of the judgment result to the effect that no detection signal was output in response to the instruction signal this time reaches 3. Thus, the number of notifications to the service person and the number of inspections by the service person can be reduced by as much as inspections and the like dealt with by the user himself as long as the consecutive occurrence number is equal to or below 2 as compared with a construction for giving a notification prompting the inspection request of the image forming apparatus10to the service person regardless of the cause of abnormality.

As a result, burdens on the service person side can be reduced more than before and the user's chances of being forced to wait on standby for the utilization of the image forming apparatus10until an abnormality solving operation by the service person is completed can be reduced.

The content of notification until the consecutive occurrence number of the judgment result to the effect that no detection signal was output in response to the instruction signal this time reaches the predetermined plural number (here, 3) includes the conformation of an abnormality and the occurrence of a sheet jam that can be highly probably dealt with by the user. Thus, the user can reliably confirm and deal with the abnormality.

The present invention can also be modified as follows instead of or in addition to the above embodiment.

[1] The motor for driving and rotating the rotary guide member30is not limited to the stepping motor51. For example, a DC motor may be used instead of the stepping motor. In the case of using the DC motor, an instruction signal may be, for example, a current signal for rotating the DC motor in such a direction as to rotate the rotary guide member30toward the reference rotational position.

[2] Although the closing of the maintenance door19is assumed as a predetermined operation which triggers the start of the process for confirming the operation of the rotary guide member30in the embodiment, the present invention is not limited to this and an operation of turning on the power button173for turning on and off power supply to the respective parts of the image forming apparatus10can also be assumed as an example of such an operation.

[3] In the embodiment, the occurrence of an abnormality in the stepping motor51and an instruction to contact the service person to inform such an occurrence are notified when the consecutive occurrence number of the judgment result to the effect that no detection signal was output in response to the instruction signal this time is 3 or larger. A judgment reference value for the consecutive occurrence number is not limited to 3 and may be any plural number.

However, as the judgment reference value increases, the number of operations imposed on the user until the user contacts the service person to inform the abnormality (operations of opening and closing the maintenance door19or turning the power button173on and off) increases to trouble the user. On the other hand, if the judgment reference value is set at 2, there is a high possibility that the user opens and closes the maintenance door19or turns the power button173on and off without reliably checking a sheet jam when the occurrence of the sheet jam is notified for the first time.

Accordingly, in the embodiment, the judgment reference value is set at 3 which is most preferable in terms of a balance between a reduction in the number of contacts with the service person and time and effort caused by the operations imposed on the user.

[4] When the consecutive occurrence number of the judgment result to the effect that no detection signal was output in response to the instruction signal this time reaches 3, both the notification informing the occurrence of an abnormality in the stepping motor51and the notification prompting the inspection request of the image forming apparatus10to the service person are given. However, either one of the notification prompting the inspection request of the image forming apparatus10to the service person and the notification leading to prompting of the inspection request of the image forming apparatus10to the service person may be given.

[5] Although the copier is adopted as the image forming apparatus10, the image forming apparatus10may be a printer or a facsimile machine without being limited to the copier.

That is to say, an image forming apparatus according to one aspect of the present invention comprises a rotary guide member including a guide path capable of permitting the passage of a sheet being conveyed and rotatable about a supporting shaft extending in a direction orthogonal to a conveying direction to change the posture thereof in such a manner that the exit of the guide path faces toward any one of at least two conveyance destinations; a motor for changing the posture of the rotary guide member; a detector for outputting a detection signal when a predetermined posture of the rotary guide member is detected; an instructing section for outputting an instruction signal to the motor to operate the rotary guide member toward the predetermined posture when a predetermined operation which triggers the start of a process for confirming the operation of the rotary guide member using the detector is performed to the image forming apparatus; a judging section for judging whether or not the detection signal has been received from the detector in response to the instruction signal by the instructing section this time; and a notifying section for counting a consecutive occurrence number of a judgment result to the effect that no detection signal was received in response to the instruction signal this time when the judging section judged that no detection signal was received in response to the instruction signal this time and giving at least one of a notification prompting an inspection request of the image forming apparatus and a notification relating to prompting of the inspection request when the consecutive occurrence number reaches a set plural number.

According to this construction, when the predetermined operation is performed, the instruction signal for operating the rotary guide member is output to the motor by the instructing section and the operation of the rotary guide member is confirmed using the detector. Then, whether or not a detection signal has been received from the detector in response to the instruction signal by the instructing section this time is judged by the judging section.

Here, when the judging section judged that no detection signal was received in response to the instruction signal by the instructing section this time, the notifying section counts the consecutive occurrence number of the judgment result to the effect that no detection signal was received in response to the instruction signal this time and gives at least one of the notification prompting the inspection request of the image forming apparatus to a service person and the notification relating to prompting of the inspection request.

In this way, the inspection request of the image forming apparatus to the service person by the user is avoided until the consecutive occurrence number of the judgment result to the effect that no detection signal was received in response to the instruction signal this time reaches the set number.

As a result, the number of notifications to the service person can be reduced by as much as inspections and the like dealt with by the user himself as compared with a construction for giving a notification prompting the inspection request of the image forming apparatus to the service person regardless of the cause of an abnormality.

The notifying section preferably assumes the occurrence of a sheet jam and gives a corresponding notification until the consecutive occurrence number reaches the set number after the first judgment by the judging section that no detection signal was received in response to the instruction signal this time.

According to this construction, the occurrence of the sheet jam that can be dealt with by the user himself is assumed and the corresponding notification is given until the consecutive occurrence number reaches the set number after the first judgment by the judging section that no detection signal was received in response to the instruction signal this time. Thus, the user can be let to confirm and deal with abnormalities as much as possible until the consecutive occurrence number reaches the set plural number.

An operation of closing an opening door for exposing the interior of the image forming apparatus and an operation of turning on a power button to supply power necessary for respective parts of the image forming apparatus are presumed as examples of the predetermined operation that triggers the start of the process for setting the rotary guide member in the predetermined posture.

The consecutive occurrence number (set number) is preferably set at 3 in view of a balance between a reduction in the number of notifications to the service person (number of operations) and time and effort of the user (time and effort resulting from the operation of opening and closing the opening door or turning the power button on and off until the notification of the occurrence of a trouble disappears).

Further, the judging section preferably judges that no detection signal was received in response to the instruction signal this time when no detection signal was output from the detector within a judgment period set beforehand after the output of the instruction signal by the instructing section was started.

Since the posture of the rotary guide member is not known when the output of the instruction signal by the instructing section is started, a period required for the rotary guide member to reach the predetermined posture after the start of the instruction signal is unknown even when the rotary guide member normally operates. Accordingly, a maximum period presumed as a period required for the rotary guide member to reach the predetermined posture after the start of the driving of the rotary guide member is, for example, set as the judgment period beforehand. If it is judged that no detection signal was received from the detector in response to the instruction signal when no detection signal was output from the detector within the judgment period after the output of the instruction signal by the instructing section was started, accuracy in judging an inoperative state of the rotary guide member is increased.

The rotary guide member further includes a guide pulley which freely rotates about a shaft parallel with the supporting shaft and a part of which projects into the guide path.

According to this construction, a sheet is permitted to smoothly pass along the guide path by the guide pulley.

It is preferable that a pair of the guide pulleys are provided and that parts of one and the other guide pulleys project into the guide path with the circumferential surfaces thereof facing each other.

According to this construction, a sheet guided into the guide path of the rotary guide member is moved by the free rotation of the guide pulleys due to the contact with the circumferential surfaces of the guide pulleys without an image forming surface of the sheet coming into contact with the inner wall surface of the guide path during the movement in the guide path. Thus, the image forming surface of the sheet is not rubbed against the inner wall surface of the guide path, whereby the occurrence of an image formation failure can be suppressed.

It is preferable that the guide path is formed by a pair of guide plates arranged to face at a distance and that one end opening between the guide plates facing each other serves as an entrance for the sheet and the other end opening serves as an exit for the sheet.

According to this construction, the guide path including the entrance and the exit can be easily formed.

It is preferable that at least one guide plate has an arcuate surface along an extending direction of the guide path and that the entrance end opening is made wider than the exit end opening by the arcuate surface.

According to this construction, the sheet can be better received into the entrance side.

It is preferable that the image forming apparatus further comprises an image forming unit for forming an image on the sheet, a first discharge tray as a first discharge destination of the sheet, a second discharge tray as a second discharge destination different from the first discharge destination, a main conveyance path for conveying the sheet via the image forming unit and an auxiliary conveyance path provided downstream of the main conveyance path and including a first auxiliary conveyance path for conveying the sheet to the first discharge tray and a second auxiliary conveyance path for conveying the sheet to the second discharge tray; and that the rotary guide member is provided between the main conveyance path and the auxiliary conveyance path for switching the sheet conveying direction with the first auxiliary conveyance path and the second auxiliary conveyance path as conveyance destinations.

According to this construction, the discharge of the sheet to the first discharge tray or to the second discharge tray can be easily and properly switched by the action of the rotary guide member.

It is preferable that the image forming apparatus further comprises, for two-sided printing, a reversing conveyance path for conveying the sheet in a reverse direction to a side of the main conveyance path upstream of the image forming unit and a switchback portion arranged downstream of the rotary guide member for switching the sheet back to feed the sheet to the reversing conveyance path; and that the auxiliary conveyance path further includes a third auxiliary conveyance path for conveying the sheet to the switchback portion.

According to this construction, the sheet can be accurately conveyed not only to the first discharge tray or the second discharge tray, but also to the reversing conveyance path for two-sided printing.

According to the above constructions, since the number of notifications to the service person can be reduced more than before, burdens on the service person side can be reduced and the user's chances of being forced to wait on standby for the utilization of the image forming apparatus until a trouble is solved by the service person can be reduced.

This application is based on Japanese patent application NO. 2009-138179, filed in Japan Patent Office on Jun. 9, 2009, the contents of which are hereby incorporated by reference.