Image forming system and stacking apparatus

An image forming system includes: an image former that forms an image; a stacker that stacks a recording medium on which an image has been formed by the image former and which has been discharged from the image former; a lifter that raises or lowers the stacker between a stacking position where the recording medium is stacked and a lower position located below the stacking position; a recording medium detector that detects the recording medium stacked on the stacker; and a hardware processor that controls driving of the lifter so as to lower the stacker from the stacking position to the lower position when it is determined that the recording medium is on the stacker on the basis of a detection result of the recording medium detector within start-up time from a time when power is switched on to a time of shifting to an image formable state.

The present invention claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2019-051422, filed on Mar. 19, 2019, the entire content of which is incorporated herein by reference.

BACKGROUND

Technological Field

The present disclosure relates to an image forming system and a stacking apparatus.

Description of the Related Art

JP 2010-189148 A discloses an image forming system including an image forming apparatus and a stacking apparatus that stacks a recording medium on which an image has been formed by the image forming apparatus. Regarding the image forming system, JP 2010-189148 A discloses that when power is switched off, a tray (stacker) on which a recording medium is stacked is lowered and the recording medium can be taken out from the apparatus, and then the power is switched off.

However, in the related art described in JP 2010-189148 A, when a trouble such as a power failure occurs and power is switched off, the stacker is not lowered, and therefore a user cannot take out the recording medium. Therefore, a user may forget to take out the recording medium from the stacker.

SUMMARY

The present invention has been achieved in view of such circumstances, and an object of the present invention is to provide an image forming system and a stacking apparatus that can prevent a user from forgetting to take a recording medium even when power is switched off due to a trouble such as a power failure and the recording medium remains in the stacker.

To achieve the abovementioned object, according to an aspect of the present invention, an image forming system reflecting one aspect of the present invention comprises: an image former that forms an image; a stacker that stacks a recording medium on which an image has been formed by the image former and which has been discharged from the image former; a lifter that raises or lowers the stacker between a stacking position where the recording medium is stacked and a lower position located below the stacking position; a recording medium detector that detects the recording medium stacked on the stacker; and a hardware processor that controls driving of the lifter so as to lower the stacker from the stacking position to the lower position when it is determined that the recording medium is on the stacker on the basis of a detection result of the recording medium detector within start-up time from a time when power is switched on to a time of shifting to an image formable state.

DETAILED DESCRIPTION OF EMBODIMENTS

First Embodiment

FIG. 1is a front view schematically illustrating a configuration of an image forming system100according to the present embodiment.FIG. 2Ais a configuration view illustrating a main part of a stacking apparatus2mainly including a first tray21and a carriage40. The image forming system100according to the present embodiment includes an image forming apparatus1and the stacking apparatus2.

The image forming apparatus1is an electrophotographic image forming apparatus such as a copying machine, and forms an image on a sheet P (recording medium) on the basis of image data. The image forming apparatus1includes a document reader5, a photoreceptor11, a charger12, an image exposing unit13, a developing unit14, a sheet cassette17A, a transfer unit15A, a separating unit15B, a cleaner16, an intermediate conveyance unit17B, a fixing device18, a sheet discharge roller17C, a conveyance path switching plate17D, a reverse conveyance unit17E, an image forming controller19(controller), a power switch91(power), and a power button92(power).

The document reader5is disposed in an upper portion of a housing1aof the image forming apparatus1, and includes an automatic document feeder that automatically moves a document when an image is read. The document reader5reads an image formed on a document and outputs a predetermined image signal. The output image signal is subjected to A/D conversion, and is thereby created as image data. An image reading controller (not illustrated) included in the document reader5performs processing such as shading correction, dither processing, or compression on the image data, and outputs data obtained by this processing as final image data to the image forming controller19.

The photoreceptor11carries an electrostatic latent image with the charger12and the image exposing unit13described later, and carries a toner image with toner of the developing unit14described later. The charger12uniformly charges a surface of the photoreceptor11. The image exposing unit13scans and exposes the surface of the photoreceptor11with a laser beam on the basis of output information output from the image forming controller19described later on the basis of the image data, and forms an electrostatic latent image. The developing unit14develops the electrostatic latent image on the surface of the photoreceptor11with toner to form a toner image.

The sheet cassette17A stores a sheet P. The transfer unit15A transfers the toner image on the surface of the photoreceptor11onto a sheet P fed from the sheet cassette17A to the transfer unit15A. The separating unit15B separates a sheet P onto which a toner image has been transferred from the photoreceptor11. The cleaner16removes toner remaining on the surface of the photoreceptor11after a toner image is transferred onto a sheet P. The intermediate conveyance unit17B conveys a separated sheet P to the fixing device18.

The fixing device18performs a fixing process for fixing an image to a sheet P by heating and pressing. The sheet discharge roller17C discharges a sheet P that has been subjected to the fixing process to the outside of the housing1a.

When image formation is performed on both sides of a sheet P, the conveyance path switching plate17D switches a conveyance direction of the sheet P that has been subjected to the fixing process by the fixing device18from the sheet discharge roller17C side to a lower (reverse conveyance unit17E) side. The reverse conveyance unit17E inverts the front and back of a sheet P by switching back the sheet P, and then conveys the sheet P to the transfer unit15A.

The image forming controller19controls the image forming apparatus1. As the image forming controller19, a microcomputer mainly including a CPU, a ROM, a RAM, and an I/O interface can be used. The CPU executes various programs (processor). The ROM stores various programs executed by the CPU in a form of program codes readable by the CPU. The ROM stores data necessary for executing a program. The RAM is a memory serving as a working storage area. When the program and data stored in the ROM are read by the CPU, the program and data are developed on the RAM. Then, the CPU performs various processes on the basis of the program and data developed on the RAM. The function of the image forming controller19will be described in detail later.

The power switch91is a main power and keeps the image forming apparatus1in an operating state all the times. If the power switch91is turned on, the image forming apparatus1can receive FAX information and form an image, or can receive data from a personal computer and form an image.

The power button92is pressed in order to shift the image forming apparatus1to a sleep state or to release the sleep state to shift the image forming apparatus1to a standby state. The power button92can shift the stacking apparatus2to a sleep state, or can release the sleep state to shift the stacking apparatus2to a standby state in addition to the image forming apparatus1.

When the power switch91is switched from off to on and the power button92is switched from off to on, the power of the image forming apparatus1is switched on. For example, when a user presses the power switch91with a finger to switch the power switch91from off to on, and then the user presses the power button92with a finger to switch the power button92from off to on, the power of the image forming apparatus1is switched on. The power switch91is pressed so as to be on but the power switch91is turned off due to a power failure, and a user presses the power button92with a finger to switch the power button92from off to on after the power failure is over and the power switch91is turned on. As a result, the power of the image forming apparatus1is switched on.

The power of the image forming apparatus1is switched off by switching the power switch91from on to off or switching the power button92from on to off

The stacking apparatus2stacks and stores a sheet P fed from the image forming apparatus1when the sheet P is taken into a housing2a(stacking apparatus main body). The stacking apparatus2is disposed on a downstream side of the image forming apparatus1in a sheet conveyance direction so as to be adjacent to the image forming apparatus1. The stacking apparatus2includes a sheet discharge unit20, a first tray21(stacker), a sheet detector55(recording medium detector), a stacking amount detector56, a lifting device24(lifter), a carriage40, a stacking controller31(controller), and a power switch93(power).

The sheet discharge unit20is formed of a pair of rollers that receives a sheet P fed from the image forming apparatus1, takes the sheet P into the housing2aof the stacking apparatus2, and discharges the sheet P to the first tray21. The position of the sheet discharge unit20is set so as to correspond to the sheet discharge roller17C of the image forming apparatus1.

On the first tray21, a sheet P on which an image has been formed by the image forming apparatus1and which has been discharged from the image forming apparatus1is stacked. The first tray21is a flat plate-like member having a horizontal plane, and receives a sheet P on the horizontal plane.

The sheet detector55detects a sheet P stacked on the first tray21and is a sensor disposed above the first tray21. For the sheet detector55, for example, a photo reflector is used. The sheet detector55includes a light emitting unit55aand a light receiving unit55b.

For example, as illustrated inFIG. 2B, when a sheet P is not disposed on the first tray21, light emitted from the light emitting unit55ais absorbed by the first tray21and does not reach the light receiving unit55b. As a result, it is determined that a sheet P is not disposed on the first tray21. As illustrated inFIG. 2C, when a sheet P is disposed on the first tray21, light emitted from the light emitting unit55ais reflected by the sheet P on the first tray21and reaches the light receiving unit55b. As a result, it is determined that a sheet P is disposed on the first tray21.

The stacking amount detector56is a sensor that is disposed on a downstream side of the sheet discharge unit20in a sheet conveyance direction and is disposed on an upstream side of the first tray21in the sheet conveyance direction. For example, a photo sensor is used for the stacking amount detector56. The stacking amount detector56includes a light emitting unit56aand a light receiving unit56b.

For example, as illustrated inFIG. 2D, when a sheet P is not interposed between the light emitting unit56aand the light receiving unit56b, light emitted from the light emitting unit56areaches the light receiving unit56b. As illustrated inFIG. 2E, when a sheet P is interposed between the light emitting unit56aand the light receiving unit56b, light emitted from the light emitting unit56ais blocked by the sheet P and does not reach the light receiving unit56b. Therefore, by counting the number of times light emitted from the light emitting unit56adoes not reach the light receiving unit56bafter the light emitted from the light emitting unit56areaches the light receiving unit56b, the stacking amount (number of sheets) of sheets P stacked on the first tray21is detected.

The lifting device24raises or lowers the first tray21between a stacking position L1(seeFIG. 5A) at which a sheet P is stacked and a lower position L2(seeFIG. 5B) located below the stacking position L1. Here, description is given with reference toFIG. 2Aagain. The lifting device24includes a base member23a, a wheel support member23b, a wheel26, a guide27, a frame35, pulleys36aand36b, and a belt37.

To the base member23a, an end surface of the first tray21is fixed. The wheel support member23bis fixed to the base member23aand supports the wheel26rotatably. The wheel26can move in the vertical direction along the guide27. Two guides27are disposed so as to extend in the vertical direction.

The frame35is disposed on the back side of the base member23a. The pulley36ais rotated by driving a motor (not illustrated), and is rotatably attached to the frame35. The pulley36bis rotatably attached to the frame35. The belt37is stretched around the pulleys36aand36b.

The carriage40includes a carrier41, a handle42, and a wheel43. The carrier41is disposed below the first tray21and receives a sheet P stacked on the first tray21from the first tray21. The handle42is attached to the carrier41and operated by a user.

The stacking controller31controls the stacking apparatus2. As the stacking controller31, a microcomputer mainly including a CPU, a ROM, a RAM, and an I/O interface can be used. The CPU executes various programs (processor). The ROM stores various programs executed by the CPU in a form of program codes readable by the CPU. The ROM stores data necessary for executing a program. The RAM is a memory serving as a working storage area. When the program and data stored in the ROM are read by the CPU, the program and data are developed on the RAM. Then, the CPU performs various processes on the basis of the program and data developed on the RAM.

The power switch93is a main power and keeps the stacking apparatus2in an operating state all the times. The power switch93is switched on or off, and the stacking apparatus2is thereby switched on or off.

Considering the power-on of the image forming apparatus1and the power-on of the stacking apparatus2, the power of the image forming system100is switched on when the power switch91and the power switch93are switched on and the power button92is further switched on.

[Component Related to Lowering Control of First Tray Among Components of Image Forming Controller and Stacking Controller]

FIG. 3is a block diagram of the image forming apparatus1and the stacking apparatus2. As illustrated inFIG. 3, the image forming controller19is connected to a continuation information receiver62, a job content storage63, a continuation command storage64, an inter-device communicator81, and an image former90. The image forming controller19has a position fixing mode. The image forming controller19includes an automatic power starter65(automatic power-on unit), a sleep mode unit66(automatic power-off unit), and an off-time measurer67.

The continuation information receiver62receives job continuation information indicating that a job executed before the power of the image forming apparatus1is switched from on to off continues when the power is next switched on. The job content storage63stores contents of a job before the image forming apparatus1is turned off. The continuation command storage64stores a command to continue a job stored in the job content storage63when the power is next switched on.

The inter-device communicator81is connected to the stacking controller31via an inter-device communicator82of the stacking apparatus2. The image former90includes the above-described photoreceptor11, charger12, image exposing unit13, developing unit14, sheet cassette17A, transfer unit15A, separating unit15B, cleaner16, fixing device18, and the like. The position fixing mode is a mode for a service person that controls driving of the lifting device24so as to keep the first tray21at the stacking position L1.

The automatic power starter65automatically switches on powers of the image forming apparatus1and the stacking apparatus2at a predetermined time. The automatic power starter65is connected in view of mechanism such that the power is turned on, but stops a current flow until a predetermined time, starts the current flow at the predetermined time, and switches on the powers of the image forming apparatus1and the stacking apparatus2. As a result, the image forming apparatus1and the stacking apparatus2start.

The sleep mode unit66automatically switches off the power button92of the image forming apparatus1when there is no user operation for a predetermined time or more. The sleep mode unit66is operable when the power switch91is in an on state. In this state, when there is no user operation for a predetermined time or more, the sleep mode unit66switches the power button92from on to off and switches off the power of the image forming apparatus1.

The off-time measurer67measures off-time from the time when the power of the image forming apparatus1is turned off to the time when the power is switched on.

[Control of Lowering First Tray Among Controls of Image Forming Controller and Stacking Controller]

The image forming controller19transmits information of being within start-up time to start the image forming system100to the stacking controller31via the inter-device communicators81and82. The stacking controller31determines that a sheet P is on the first tray21on the basis of a detection result of the sheet detector55within the start-up time. In this case, the stacking controller31controls driving of the lifting device24so as to lower the first tray21from the stacking position L1to the lower position L2.

The start-up time here refers to a period of time from the time when power is switched on to the time of shifting to an image formable state. The time when power is switched on is the time when the power switches91and93are switched on and the power button92is switched on as described above. The image formable state is a state where preparation for starting image formation such as initial driving is completed. The image forming controller19lowers the first tray21by controlling rotation of a motor (not illustrated) that drives the pulley36a.

[Control that does not Lower First Tray Among Controls of Image Forming Controller and Stacking Controller]

It is assumed that the image forming controller19transmits job continuation information received by the continuation information receiver62to the stacking controller31via the inter-device communicators81and82. In this case, the stacking controller31controls driving of the lifting device24so as to keep the first tray21at the stacking position L1.

It is assumed that the image forming controller19receives a signal that the continuation information receiver62stops the job after the power is switched on and transmits the signal to the stacking controller31via the inter-device communicators81and82. In this case, the stacking controller31controls driving of the lifting device24so as to lower the first tray21from the stacking position L1to the lower position L2.

It is assumed that the image forming controller19transmits setting information for automatically switching on powers of the image forming apparatus1and the stacking apparatus2included in the automatic power starter65at a predetermined time to the stacking controller31via the inter-device communicators81and82. In this case, the stacking controller31controls driving of the lifting device24so as to keep the first tray21at the stacking position L1.

It is assumed that the image forming controller19transmits switching information indicating that the off state by the sleep mode unit66is released and the power is switched on to the stacking controller31via the inter-device communicators81and82. In this case, the stacking controller31controls driving of the lifting device24so as to keep the first tray21at the stacking position L1.

It is assumed that the image forming controller19receives that off-time measured by the off-time measurer67is a predetermined time or less as information and transmits the information to the stacking controller31via the inter-device communicators81and82. In this case, the stacking controller31controls driving of the lifting device24so as to keep the first tray21at the stacking position L1.

It is assumed that the image forming controller19transmits selection information of a position fixing mode to the stacking controller31via the inter-device communicators81and82when the position fixing mode is selected. In this case, the stacking controller31controls driving of the lifting device24so as to keep the first tray21at the stacking position L1even when the power is switched on.

It is assumed that the stacking controller31determines that the stacking amount of sheets P on the first tray21is a predetermined amount or less on the basis of a detection result of the stacking amount detector56. In this case, the stacking controller31controls driving of the lifting device24so as to keep the first tray21at the stacking position L1.

The stacking controller31determines whether the carriage40is disposed below the first tray21. The stacking controller31does not drive the lifting device24when the carriage40is not disposed. When the carriage40is disposed, the stacking controller31controls driving of the lifting device24such that the first tray21is lowered to the lower position and the carriage40receives a sheet P.

[Control of First Tray by Stacking Controller]

As illustrated inFIG. 3, the stacking controller31is connected to the lifting device24, the sheet detector55, the stacking amount detector56, and the inter-device communicator82. The stacking controller31controls driving of the lifting device24such that the first tray21is disposed at the stacking position L1while a sheet P on which an image has been formed is discharged from the image forming apparatus1. When a sheet P is discharged from the sheet discharge unit20, the stacking controller31controls driving of the lifting device24so as to lower (move) the first tray21such that an uppermost sheet P stacked on the first tray21maintains a predetermined height.

The stacking position L1of the first tray21here is a home position L10(seeFIG. 5A) of the first tray21when stacking of a sheet P is started in a case where no sheet P is disposed on the first tray21. The stacking position L1of the first tray21is a stacking intermediate position L11(seeFIG. 5A) of the first tray21when the position of an uppermost surface of sheets P is set to the position of the first tray21at the time of start of stacking the sheets P in a case where the number of sheets P set by a user are disposed on the first tray21. Therefore, the stacking position L1corresponds to a position from the home position L10of the first tray21when no sheet P is stacked on the first tray21to the stacking intermediate position L11of the first tray21when the set number of sheets P are stacked on the first tray21.

When the number of sheets P stacked on the first tray21reaches the set number, the lifting device24lowers the first tray21to the lower position L2where the sheets P can be taken out with respect to the carriage40. When the sheets P are completely taken out from the first tray21to the carriage40, the lifting device24raises the first tray21from the lower position L2to the home position L10.

Hereinafter, operation of the image forming system100according to the present embodiment will be described. Here,FIG. 4is a flowchart illustrating a flow of control of the first tray21within start-up time.FIGS. 5A to 5Dare explanatory diagrams for explaining a flow of operation of the first tray21. The processing illustrated in this flowchart is executed by the image forming controller19and the stacking controller31with a user's print start command as a trigger.

First, in step S10, a user turns on powers of the image forming apparatus1and the stacking apparatus2. The image forming controller19starts devices in the image forming apparatus1and the stacking apparatus2within start-up time from the time when powers of the image forming apparatus1and the stacking apparatus2are switched on to the time when the image forming apparatus1is shifted to an image formable state.

In step S11, the stacking controller31determines whether there is a sheet P on the first tray21on the basis of a detection result of the sheet detector55. If there is a sheet P on the first tray21, an affirmative determination is made in step S11, and the process proceeds to step S12. The sheet P on the first tray21was stacked on the first tray21when the power was previously turned on. Meanwhile, if there is no sheet P on the first tray21, negative determination is made in step S11, and control within the start-up time is ended.

In step S12, the image forming controller19determines whether the continuation information receiver62has received job continuation information indicating that a job before power off is continued after the next power on. If the continuation information receiver62has received the job continuation information, an affirmative determination is made in step S12, and the process proceeds to step S14. Meanwhile, if the continuation information receiver62has not received the job continuation information, a negative determination is made in step S12, and the process proceeds to step S13.

In step S13, the image forming controller19confirms whether the automatic power starter65has set power start-up time. If the start-up time has been set by the automatic power starter65, an affirmative determination is made in step S13, and control within the start-up time is ended. Meanwhile, if the start-up time has not been set by the automatic power starter65, a negative determination is made in step S13, and the process proceeds to step S15.

In step S14, if the continuation information receiver62has received the job continuation information, the image forming controller19determines whether a job stop signal for stopping the job received by the continuation information receiver62has been received. If the job stop signal has been received, an affirmative determination is made in step S14, and the process proceeds to step S18. Meanwhile, if the job stop signal has not been received, a negative determination is made in step S14, and the process returns to step S14.

In step S15, the image forming controller19confirms whether power (power button92) has been turned on by release of the sleep mode by the sleep mode unit66. If power (power button92) has been turned on by release of the sleep mode, an affirmative determination is made in step S15, and control within the start-up time is ended. Meanwhile, if power (power button92) has not been switched on by release of the sleep mode, a negative determination is made in step S15, and the process proceeds to step S16.

In step S16, the image forming controller19confirms that off-time measured by the off-time measurer67is a predetermined time or less. If the off-time is the predetermined time or less, an affirmative determination is made in step S16, and control within the start-up time is ended. Meanwhile, if the off-time is more than the predetermined time, a negative determination is made in step S16, and the process proceeds to step S17.

In step S17, the image forming controller19confirms whether the mode is a position fixing mode for a service person. If the mode is a position fixing mode for a service person, an affirmative determination is made in step S17, and control within the start-up time is ended. Meanwhile, if the mode is not a position fixing mode for a service person, a negative determination is made in step S17, and the process proceeds to step S18.

In step S18, the stacking controller31confirms whether the number of sheets P stacked on the first tray21detected by the sheet detector55is a predetermined number or more. If the stacking amount of sheets P on the first tray21is the predetermined number or more, an affirmative determination is made in step S18, and control within the start-up time is ended. Meanwhile, if the stacking amount of sheets P stacked on the first tray21is less than the predetermined number, a negative determination is made in step S18, and the process proceeds to step S19.

In step S19, the stacking controller31determines whether the carriage40is disposed below the first tray21(seeFIG. 5A). If the carriage40is not disposed below the first tray21, an affirmative determination is made in step S19, and the process proceeds to step S21. Meanwhile, if the carriage40is disposed below the first tray21, a negative determination is made in step S19, and the process proceeds to step S20.

In step S20, the stacking controller31lowers the first tray21toward the carriage40, and ends control within the start-up time.

Thereafter, a user moves a sheet P on the first tray21onto the carriage40(seeFIG. 5B). A user discharges the carriage40outside the image forming apparatus1(seeFIG. 5C). When the carriage40is discharged outside the image forming apparatus1, the stacking controller31raises the first tray21(seeFIG. 5D). Thereafter, furthermore, the image forming controller19executes an image forming operation. By this image forming operation, a series of processes such as feeding of a sheet P, forming an image on a fed sheet P, and discharging a sheet P on which an image has been formed to the stacking apparatus2are performed. The stacking controller31controls driving of the sheet discharge unit20, receives a sheet P fed from the image forming apparatus1in the sheet discharge unit20, and discharges the sheet P to the first tray21.

In step S21, the stacking controller31determines whether the carriage40is prepared. If the carriage40is prepared, an affirmative determination is made in step S21, and the process proceeds to step S20. If the carriage40is not prepared, a negative determination is made in step S21, and the process returns to step S21.

As described above, in the present embodiment, the image forming controller19recognizes a state within the start-up time from the time when power of the image forming apparatus1is switched on to the time when the image forming apparatus1is shifted to an image formable state. Within this start-up time, the stacking controller31controls driving of the lifting device24so as to lower the first tray21from the stacking position L1to the lower position L2when the sheet detector55detects a sheet P. This configuration can prevent a user from forgetting to take a sheet P even when power is switched off due to a trouble such as a power failure and the sheet P remains in the first tray21. Immediately after power of the image forming system100is switched on, presence of a sheet P on the first tray21indicates that there is a high possibility that a user has forgotten to take the sheet P. Therefore, when the power is switched on, the first tray21is controlled so as to be automatically lowered to the lower position L2, and a user is urged to take out the sheet P.

In addition, the image forming system100includes the continuation information receiver62that receives job continuation information indicating that a job executed before the powers of the image forming apparatus1and the stacking apparatus2are switched from on to off continues when the powers are next switched on. The image forming controller19receives information indicating that the continuation information receiver62has received the job continuation information, and transmits the information to the stacking controller31. The stacking controller31controls driving of the lifting device24so as to keep the first tray21at the stacking position L1. According to this configuration, when there is a job to be continued, the first tray21is not lowered to the lower position L2, but the job is continuously executed immediately. Therefore, convenience and productivity for a user are improved. For example, there is a case where a large number of jobs are output until 5:00 pm that is closing time, the power is turned off with work unfinished, and the power is turned on the next day at 9:00 am to continue output of the jobs. In this case, even if the power is switched on, the first tray21is not lowered, but the job is continued, which is convenient for a user

The image forming controller19transmits the job stop information received by the continuation information receiver62to the stacking controller31after the power of the image forming apparatus1is switched on. The stacking controller31controls driving of the lifting device24so as to lower the first tray21to the lower position L2. According to this configuration, when there is no job to be output on the next day and to be continued, the first tray21is lowered to the lower position L2where a sheet P is easily taken out even if there is no instruction to lower the first tray21by a user. Therefore, a user can be prevented from forgetting to take the sheet P

The image forming system100also includes the automatic power starter65that automatically switches on the power of the image forming apparatus1at a predetermined time. The image forming controller19transmits switching information indicating that the power of the image forming apparatus1is turned on and set by the automatic power starter65to the stacking controller31. The stacking controller31controls driving of the lifting device24so as to keep the first tray21at the stacking position L1. A user can use this configuration, for example, in a case where working hours of the user's company start at 9:00 am, when the user desires to set the image forming apparatus1such that the image forming apparatus1is automatically turned on 8:55 am by operating the automatic power starter65. With this setting, the power is turned on immediately before the user's working hours and the image forming apparatus1is warmed up. Therefore, the user's standby time can be shortened. If the power is turned on at night when there is no user, confidentiality of information an image of which has been formed on a sheet P may be impaired. Therefore, confidentiality is maintained.

The image forming system100also includes the sleep mode unit66that automatically switches off the power (power button92) of the image forming apparatus1when there is no user operation for a predetermined time or more. The image forming controller19transmits switching information indicating that the off state by the sleep mode unit66is released and the power (power button92) is switched from off to on to the stacking controller31. The stacking controller31controls driving of the lifting device24so as to keep the first tray21at the stacking position L1. According to this configuration, for example, a user can suppress a phenomenon that the first tray21is lowered every time the image forming apparatus1is released from the sleep mode. That is, in the sleep mode, a user does not intend to stop outputting a job for a long time in some cases. For this reason, the job is restored immediately after release of the sleep mode, and the job can be output, which is convenient for a user

In addition, the image forming system100includes the off-time measurer67that measures off-time from the time when the power of the image forming apparatus1is turned off to the time when the power is switched on. The image forming controller19determines that the off-time measured by the off-time measurer67is a predetermined time or less. In this case, the stacking controller31controls driving of the lifting device24so as to keep the first tray21at the stacking position L1. According to this configuration, when the off-time is the predetermined time or less, there is a high possibility that a user has a weak intention (or no intention) to switch off the power. For this reason, the user can execute next image formation while the first tray21is not lowered to the lower position L2, which is convenient for a user

The image forming controller19has a position fixing mode for a service person, the mode controlling driving of the lifting device24so as to keep the first tray21at the stacking position L1. According to this configuration, since the first tray21is not lowered to the lower position L2every time powers of the image forming apparatus1and the stacking apparatus2are turned on, a service person can immediately perform maintenance work of the image forming system100, which is convenient for a service person.

The sheet detector55detects the stacking amount of sheets P stacked on the first tray21. When the stacking amount detected by the sheet detector55is a predetermined amount or less, the stacking controller31controls driving of the lifting device24so as to keep the first tray21at the stacking position L1. According to this configuration, when the stacking amount of sheets P is the predetermined amount or less, a user can take out a sheet P by himself/herself while the first tray21is not lowered to the lower position L2. For example, if the stacking amount of sheets P is 3000 sheets, the weight may exceed 70 kg, and it is difficult for a user to take out a bundle of sheets P manually. However, if the stacking amount of sheets P is small, a user can easily take out a bundle of sheets P manually. Since time and electric power are required for lowering the first tray21, such time and electric power are reduced when the stacking amount of sheets P is small.

The stacking controller31determines whether the carriage40is disposed below the first tray21. The stacking controller31does not drive the lifting device24when the carriage40is not disposed. The stacking controller31controls driving of the lifting device24such that the first tray21is lowered to the lower position and the carriage40receives a sheet P when the carriage40is disposed. According to this configuration, even if a user does not give an instruction to lower the first tray21after setting the carriage40, the first tray21can be automatically lowered immediately.

Second Embodiment

FIG. 6is a front view schematically illustrating a configuration of an image forming system200according to a second embodiment. Hereinafter, the image forming system200according to the second embodiment will be described with reference toFIG. 6. The image forming system200according to the second embodiment is different from the image forming system100according to the first embodiment in the configuration of the stacking apparatus2. Description overlapping with that of the first embodiment is omitted, and the following description will be focused on the difference.

A stacking apparatus2includes a sheet discharge unit20, a first tray21(stacker), a sheet detector55(recording medium detector), a stacking amount detector56, a lifting device24(lifter), a second tray25(receiver), a front/rear drive device28(mover), and a stacking controller31.FIG. 7is a configuration view illustrating a main part of the stacking apparatus2mainly including the first tray21and the second tray25. The configurations of the sheet discharge unit20, the sheet detector55, and the stacking amount detector56are similar to the configurations thereof in the first embodiment, and description thereof is omitted.

On the first tray21, a sheet P that has been discharged from the sheet discharge unit20is stacked. The first tray21has a plurality of comb teeth21aand a support21b. The plurality of comb teeth21aextends in a direction perpendicular to a sheet conveyance direction and in the horizontal direction. The plurality of comb teeth21ais arranged in the horizontal direction at a predetermined pitch in the sheet conveyance direction. The plurality of comb teeth21ais arranged such that upper surfaces21cthereof are located on the same horizontal plane. The support21bsupports horizontal ends (longitudinal ends) of the plurality of comb teeth21a. The support21bis fixed to a base member23alocated on a rear side (apparatus back side).

The lifting device24raises or lowers the first tray21between a stacking position L1at which a sheet P is stacked and a lower position L2located below the stacking position L1. When the number of sheets P stacked on the first tray21reaches the set number, the lifting device24lowers the first tray21from the stacking position L1to the lower position L2. When delivery of a sheet P from the first tray21to the second tray25is completed, the lifting device24raises (moves) the first tray21from the lower position L2to a home position L10(seeFIG. 10A).

The second tray25is disposed below the first tray21and receives a sheet P stacked on the first tray21when the first tray21is lowered. The second tray25has a plurality of comb teeth25aand a support25b. The plurality of comb teeth25aextends in a direction perpendicular to a sheet conveyance direction and in the horizontal direction. The plurality of comb teeth25ais arranged in the horizontal direction at a predetermined pitch in the sheet conveyance direction. The plurality of comb teeth25ais arranged such that upper surfaces25cthereof are located on the same horizontal plane. Each of the comb teeth25aprotrudes upward from an upper surface of the support25b. The plurality of comb teeth25ais fixed to a surface of the support25b, and the support25bis fixed to a pedestal29of the front/rear drive device28described later.

FIG. 8is an explanatory diagram illustrating a relationship between the first tray21and the second tray25. The plurality of comb teeth25aof the second tray25is disposed at positions corresponding to spaces (gaps) between the plurality of comb teeth21aformed on the first tray21. Therefore, even when the first tray21moves downward and the first tray21and the second tray25exist on the same horizontal plane, the first tray21and the second tray25do not interfere with each other. That is, the first tray21and the second tray25can pass each other in the vertical direction.

With this configuration, the upper surface21cof the first tray21is lowered below the upper surface25cof the second tray25, and a sheet P stacked on the first tray21can be thereby delivered to the second tray25. The above-described lower position L2for delivering a sheet P is determined in advance as a position where the upper surface21cof the first tray21exists below the upper surface25cof the second tray25according to the height of the second tray25.

Here, the configuration will be described with reference toFIG. 7again. The front/rear drive device28includes the pedestal29and a drive unit30. On the pedestal29, the second tray25is detachably mounted. The drive unit30includes a pedestal support32(seeFIG. 10C) and a guide33(seeFIG. 10C). The pedestal support32is guided by the guide33and can move between the lower position L2(seeFIG. 10B) inside a housing2aand an outer position L3(seeFIG. 10C) outside the housing2a. Therefore, the pedestal29on the pedestal support32can move in the front-rear direction by driving of the drive unit30, and the second tray25on the pedestal29can be discharged to the outside of the housing2a.

The front/rear drive device28disposes the second tray25below the first tray21inside the housing2a. When a sheet P is delivered from the first tray21to the second tray25, the front/rear drive device28moves the second tray25and the pedestal29to the front side, and sends out the second tray25and the pedestal29to the outside of the housing2a. A user inserts a carrier41of the carriage40between the pedestal29and the pedestal support32. When a user moves the carriage40away from the stacking apparatus2, the second tray25is removed from the pedestal29and attached to the carriage40. As a result, a user can convey the carriage40while the second tray25on which a sheet P is placed is mounted on the carriage40.

Thereafter, a user removes the sheet P from the second tray25mounted on the carriage40, removes the second tray25from the carriage40, and attaches the second tray25to the pedestal29. When the second tray25is attached to the pedestal29, the front/rear drive device28moves the second tray25into the housing2aand returns the first tray21to the home position L10. Note that the housing2aof the stacking apparatus2has a shutter83(seeFIGS. 10A to 10E). The shutter83is opened or closed in response to enter/exit of the second tray25.

The image forming controller19transmits that the time is within the start-up time from the time when power that switches on/off of a current flowing in the system is switched on to the time of shifting to an image formable state as information to the stacking controller31. When the sheet detector55detects a sheet P within the start-up time, the stacking controller31controls driving of the lifting device24such that the first tray21is lowered from the stacking position L1to the lower position L2and the second tray25receives the sheet P, and controls driving of the front/rear drive device28such that the second tray25is moved from the lower position L2in the system to the outer position L3outside the system.

FIG. 9is a flowchart illustrating a flow of control of the first tray21and the second tray25within start-up time.FIGS. 10A to 10Eare explanatory diagrams for explaining a flow of operation of the first tray21and the second tray25. The processing illustrated in this flowchart is executed by the image forming controller19and the stacking controller31with a user's print start command as a trigger. S10to S17are described in a similar manner toFIG. 4, and therefore description thereof is omitted.

In step S18, the stacking controller31confirms whether the number of sheets P stacked on the first tray21detected by the sheet detector55is a predetermined number or more. If the stacking amount of sheets P on the first tray21is the predetermined number or more, an affirmative determination is made in step S18, and control within the start-up time is ended. Meanwhile, if the stacking amount of sheets P stacked on the first tray21is less than the predetermined number, a negative determination is made in step S18, and the process proceeds to step S30.

In step S30, the stacking controller31determines whether the second tray25is disposed below the first tray21(seeFIG. 10A). If the second tray25is not disposed below the first tray21, an affirmative determination is made in step S30, and the process proceeds to step S32. Meanwhile, if the second tray25is disposed below the first tray21, a negative determination is made in step S30, and the process proceeds to step S31.

In step S31, the stacking controller31controls driving of the lifting device24to lower the first tray21(seeFIG. 10A). The first tray21is lowered until the first tray21reaches the lower position L2for delivering a sheet P (seeFIG. 10B). The lower position L2is set according to the height of the second tray25mounted on the pedestal29. When the first tray21reaches the lower position L2, the upper surface25cof the second tray25arrives above the upper surface21cof the first tray21. Therefore, a sheet P stacked on the first tray21is delivered from the first tray21to the second tray25(seeFIG. 10B).

In step S33, the stacking controller31controls the front/rear drive device28to move the pedestal29forward (seeFIG. 10C), and ends control in-start-up time.

Note that this forward movement is performed until the pedestal29and the second tray25are discharged to the outside of the stacking apparatus2. Thereafter, the stacking controller31controls the lifting device24to raise the first tray21to the home position L10(seeFIG. 10D). Thereafter, the second tray25discharged to the outside of the image forming apparatus1is removed from the pedestal29while the sheet P is stacked on the second tray25, and is attached to the carriage40prepared outside the image forming apparatus1(seeFIG. 10E). A user can convey the carriage40while the second tray25on which the sheet P is placed is fixed onto the carriage40.

Thereafter, when a user removes the sheet P stacked on the second tray25and the second tray25becomes empty, a user removes the second tray25from the carriage40and attaches the second tray25to the pedestal29. When the second tray25is attached, the stacking controller31controls the front/rear drive device28to move the pedestal29backward. This backward movement is performed until the pedestal29and the second tray25mounted thereon reach the home position of the housing2a. As a result, the second tray25is returned to the inside of the apparatus.

In step S32, the stacking controller31determines whether the second tray25is prepared. If the second tray25is prepared, an affirmative determination is made in step S32, and the process proceeds to step S31. If the second tray25is not prepared, a negative determination is made in step S32, and the process returns to step S32.

Note that the second tray25is preferably returned to the pedestal29before the number of sheets P stacked on the first tray21reaches the set number. When the pedestal29is discharged to the outside of the apparatus and is left as it is, the pedestal29may be impeditive. Therefore, the pedestal29may be returned to the inside of the apparatus before the second tray25is removed from the pedestal29and attached to the pedestal29again.

As described above, in the present embodiment, the image forming controller19recognizes a state within the start-up time from the time when power of the image forming apparatus1is switched on to the time when the image forming apparatus1is shifted to an image formable state. When the sheet detector55detects a sheet P within the start-up time, the stacking controller31controls driving of the lifting device24such that the first tray21is lowered from the stacking position L1to the lower position L2and the second tray25receives the sheet P, and controls driving of the front/rear drive device28such that the second tray25is moved to the outer position L3outside the system. According to this configuration, even in a case where power is switched off due to a trouble such as a power failure and a sheet P remains in the first tray21, when the power is turned on, the first tray21is automatically lowered, the sheet P is delivered to the second tray25, and the second tray25is automatically moved out of the system. Therefore, it is possible to prevent a user from forgetting to take the sheet P.

When the continuation information receiver62receives job continuation information, when the off state of the power button92by the sleep mode unit66is released and the power button92is switched on, when the off-time measured by the off-time measurer67is a predetermined time or less, when the mode is a position fixing mode for a service person, or when it is determined that the stacking amount of sheets P is a predetermined amount or less on the basis of a detection result detected by the stacking amount detector56, the stacking controller31controls driving of the lifting device24so as to keep the first tray21at the stacking position L1, and controls driving of the front/rear drive device28so as to keep the second tray25at a position in the system (lower position L2).

Hereinabove, the image forming system and the stacking apparatus according to an embodiment of the present invention have been described. However, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the invention.

For example, in the present embodiments, the control of the image forming controller19and the control of the stacking controller31are independent from each other. However, the present invention is not limited to the above embodiments. The image forming controller may include the configuration of the stacking controller31, and the image forming controller may perform control including control of the stacking controller31.

In the present embodiments, the stacking amount of sheets P on the first tray21is based on the number of sheets P stacked. However, the present invention is not limited to the above embodiments. The stacking amount of sheets P on the first tray21may be based on the position of the first tray21on which the sheets P are stacked, the height of the sheets P stacked on the first tray21, or the weight of the sheets P stacked on the first tray21.

In the present embodiments, it is determined that there is a sheet P on the first tray21within the start-up time from the time when power of the image forming apparatus1is switched on to the time when the image forming apparatus1is shifted to an image formable state. However, the present invention is not limited to the above embodiments. It may be determined that there is a sheet P on the first tray21within start-up time from the time when power of the stacking apparatus2is switched on to the time of shifting to an image formable state.

In the present embodiments, the image forming system100includes two apparatuses of the image forming apparatus1and the stacking apparatus2. At the same time, this means that the image forming system100includes a component of the image former90and a component of the stacking apparatus2. The present invention is not limited to the above-described embodiments, and the image forming apparatus1may be regarded as an apparatus including a component of the image former90and a component of the stacking apparatus2.

In the present embodiments, each of the image forming apparatus1and the stacking apparatus2includes a power switch and a power button. However, the present invention is not limited to the above embodiments. The image forming apparatus1is connected to the stacking apparatus2via a cable (not illustrated). When power of the image forming apparatus1is switched on by operation of the power switch91and the power button92of the image forming apparatus1, power of the stacking apparatus2may be switched on. Similarly, when power of the image forming apparatus1is switched off by operation of the power switch91and the power button92of the image forming apparatus1, power of the stacking apparatus2may be switched off.