Image forming apparatus

An image forming apparatus includes an attachment portion, an attachment detection unit, an output portion, a first cover, a first detection portion, a second cover, and a control unit. A control unit is configured to control opening movement of the first cover to open the first cover linked with movement that the second cover is opened when the output portion outputs information of replacing the developer accommodating container. After the first detection portion detects that the first cover is in a closed state after the first cover has been opened based on information output by the output portion, the first detection portion detects whether the developer accommodating container is attached to the attachment portion or not, and if the first detection portion detects that the developer accommodating container is not attached to the attachment portion, the control unit controls the first cover to open.

BACKGROUND OF THE INVENTION

Field of the Invention

Description of the Related Art

As an image forming apparatus of an electrophotographic system, the image forming apparatus in which a toner is filled in a developer accommodating container (hereinafter referred to as a toner container) which is disposed in an attachable and detachable manner to and from an apparatus body is widely used in the market. In general, in a case where a residual quantity of the toner in the toner container is lessened and it becomes unable to supply a desired quantity of the toner to a developing unit, a control unit provides a message on a display to urge a user to replace the toner container and notifies the user that the time has come to replace the toner container.

Further, as the image forming apparatus, different from a front cover (a second cover) disposed at a front face of the apparatus body, a configuration to dispose a small door (a first cover), by which each of insertion slots of toner containers is made openable and closable, inside the front cover is suggested (Japanese Patent Laid-Open No. 2011-59296). In this suggested image forming apparatus, when the user opens the front cover in accordance with a displayed replacement message after the toner in the toner container has been lessened, only the small door corresponding to the toner container whose toner has been lessened is automatically opened. When the user has replaced the toner container, and has closed the small door and then the front cover, the toner is supplied to the apparatus body from a replaced toner container. To be noted, in a case where the toner container has been unattached, the message is displayed, and an image formation is not performed until the toner container is attached.

However, in the image forming apparatus disclosed in Japanese Patent Laid-Open No. 2011-59296 described above, in a case where the toner container is unattached, the display of the message about an unattachment of the toner container is provided after the small door and the front cover have been closed. Thus, the user then finds out the unattachment of the toner container, and thereafter needs to carry out complicated works, i.e. opening the front cover by hands, waiting for the small cover to open automatically, and attaching a new toner container to the apparatus body.

The present invention provides the image forming apparatus which improves an operability in a case where the toner container is unattached at the replacement of the toner container.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, an image forming apparatus includes an attachment portion which is provided in the image forming apparatus and to which a developer accommodating container configured to accommodate a developer is detachably attached, an attachment detection unit configured to detect whether the developer accommodating container is attached to the attachment portion, an output portion configured to output information of replacing the developer accommodating container, a first cover disposed at the attachment portion and configured to be opened to an open state where the developer accommodating container is attachable to and detachable from the attachment portion and closed to a closed state where the developer accommodating container is not attachable to nor detachable from the attachment portion, a first detection portion configured to detect the open state and the closed state of the first cover, a second cover configured to be opened to an open state where the first cover is exposed in an openable and closable manner and closed to a closed state where the first cover is covered, and a control unit configured to control opening movement of the first cover to open the first cover linked with movement that the second cover is opened when the output portion outputs the information of replacing the developer accommodating container. After the first detection portion detects that the first cover is in the closed state after the first cover has been opened based on the information output by the output portion, the first detection portion detects whether the developer accommodating container is attached to the attachment portion or not, and if the first detection portion detects that the developer accommodating container is not attached to the attachment portion, the control unit controls the first cover to open.

According to a second aspect of the present invention, an image forming apparatus includes a developer accommodating container configured to be detachably attached to an apparatus body and accommodate a developer inside, an attachment portion which is provided in the apparatus body and to which the developer accommodating container is attached, a first cover configured to be opened to an open state where an opening portion of the attachment portion is opened and closed to a closed state where the opening portion is closed, a first detection portion configured to detect an open state and a closed state of the first cover, a driving unit configured to bring the first cover from the closed state to the open state, an attachment detection unit configured to detect whether or not the developer accommodating container is attached to the attachment portion, and a control unit configured to control the driving unit to bring the first cover from the closed state to the open state in a case where the attachment detection unit detects an unattachment of the developer accommodating container to the attachment portion and the first detection portion detects that the first cover is in the closed state.

DESCRIPTION OF THE EMBODIMENTS

First Embodiment

Hereinafter, a first embodiment of the present disclosure will be described in detail with reference toFIGS.1to8. To be noted, a tandem type full color printer is described as an example of an image forming apparatus in a first embodiment. However, this disclosure is not limited to the tandem type image forming apparatus, and the image forming apparatus of another system is acceptable. Further, this disclosure is not limited to the full color printer, and a monochrome or mono-color printer is acceptable.

General Configuration of Image Forming Apparatus

As shown inFIG.2, the image forming apparatus1includes an apparatus body10, an image reading unit20, a sheet feeding unit30, an image forming unit40, and a control unit70. As shown inFIGS.1and2, an operation unit11is disposed at a front upper position of the apparatus body10. Other than operation buttons, an operation panel, i.e., display unit11a, which is capable to display a state of the image forming apparatus1and consists of a touch panel with a touch operation capability is disposed in the operation unit11. The operation panel11ais coupled to the control unit70, and capable to output information from the control unit70, and also capable to input information by the touch operation of a user to the control unit70. To be noted, in this description, a front direction and back side direction of the image forming apparatus1are respectively referred to as a forward F and backward B.

As shown inFIG.2, the image reading unit20is disposed in an upper part of the apparatus body10. The image reading unit20includes a platen glass, not shown, as a document placing plate, a light source, not shown, to irradiate a light on a document placed on the platen glass, and an image sensor, not shown, to convert a reflected light into a digital signal. The sheet feeding unit30is disposed in a lower part of the apparatus body10, and includes a sheet cassette31to pile and store a sheet S, and a feed roller32. The sheet feeding unit30feeds the stored sheet S to the image forming unit40in a timing synchronizing with a toner image transferred onto an intermediate transfer belt44b, described later. To be noted, the sheet S is a recording material on which the toner image is formed, and includes, for example, a standard paper, a sheet made of a resin which substitutes the standard paper, a cardboard, and a sheet for an overhead projector.

The image forming unit40includes image forming units80y,80m,80c, and80k, a laser scanner43, an intermediate transfer unit44, a secondary transfer unit45, and a fixing unit46. The image forming unit40is capable of forming an image on the sheet S based on an image information. The image forming apparatus1of the first embodiment corresponds to a full color printing. In this regard, the image forming units80y,80m,80c, and80krespectively correspond to 4 colors of yellow (y), magenta (m), cyan (c), and black (k), and are disposed independently from each other with a similar configuration. To be noted, the image forming units80y,80m,80c, and80kincluded in the image forming apparatus1are similar in a structure except for a difference in a color of a developer. Therefore, the image forming unit80ywill be described below as a representative, and descriptions of other image forming units are omitted herein.

In a case of the first embodiment, a toner container, i.e., developer accommodating container42, is attached to the apparatus body10to store the developer which is supplied to a developing unit83, described later, of the image forming unit80y. The toner container42is, similar to the image forming units80y,80m,80c, and80k, provided for each of 4 colors of yellow (y), magenta (m), cyan (c), and black (k) with a same configuration, and disposed independently from each other. The toner container42is capable of storing the developer, and disposed above the image forming unit80y. The toner container42is attached to an attachment portion12yof a hole shape (refer toFIG.1) disposed in the apparatus body10in an attachable and detachable manner. A plurality of the attachment portions12y,12m,12c, and12kare disposed corresponding to the toner containers of the different colors.

The toner container42is, for example, a cylindrical bottle with a toner discharge port at a first end, and having a spiral projection portion on an inner circumferential surface. By rotating the projection portion, the toner container42conveys the toner to the toner discharge port on the backward B. A supply mechanism, not shown, is disposed on the backward direction B of the attachment portion12y, and an end of the toner container42on the backward B attached to the attachment portion12yis coupled to the supply mechanism. A toner container drive motor47(refer toFIG.3) is disposed in the supply mechanism, and the toner container drive motor47drivingly rotates the toner container42to convey the toner to the supply mechanism. That is, with respect to an insert direction to insert the toner container42into the attachment portion12y, the drive motor47is disposed downstream of the attachment portion12y. Then, a pump included in the supply mechanism is moved by rotation of the toner container42, and discharges and supplies the toner conveyed to the supply mechanism to the developing unit83. In the first embodiment, the toner which is obtained by kneading a binder resin mainly composed of polyester with a pigment and thereafter pulverized and classified is used, and has an average particle size of approximately 6 μm.

As shown inFIG.1, in a forepart of the apparatus body10, a plurality of small doors, i.e., first covers,13y,13m,13c, and13kare disposed in an openable and closable manner corresponding to the attachment portions12y,12m,12c, and12k, respectively. That is, with respect to the insert direction of the toner container42, the small door13yis disposed upstream of the attachment portion12y. For example, when the small door13yis opened, the toner container42is attachable to and detachable from the forepart of the apparatus body10. Similarly, when the small doors13m,13c, and13kare opened, the respective toner containers are attachable to and detachable from the forepart of the apparatus body10. That is, the small door13yis openable and closable so that the toner container42is capable of attaching to and detaching from the attachment portion12yin an open state of the small door13y, and the toner container42is not capable of attaching to and detaching from the attachment portion12yin a closed state of the small door13y. To be noted, a detailed configuration of the small door13ywill be described later.

In the forepart of the apparatus body10, a front cover, i.e., second cover14, which is capable of opening by pivoting to the forward F is disposed. The front cover14is openable and closable so that the front cover14exposes the small door13yin the open state and covers the small door13yin the closed state. That is, the front cover14in the open state exposes the small doors13y,13m,13c, and13kin the openable and closable manner, and in the closed state covers the small doors13y,13m,13c, and13k. Although, in the first embodiment, all the small doors13y,13m,13c, and13kare covered with one piece of the front cover14, it is acceptable to include a plurality of the front covers (for example 2) and configure to cover one or plurality of the small door(s) with the respective plurality of the front covers. As shown inFIGS.1and2, the front cover14is capable of exposing and covering, by an opening and closing thereof, the image forming units80y,80m,80c, and80kand the intermediate transfer unit44, in addition to the small doors13y,13m,13c, and13k. Therefore, it is possible to perform a replacement or inspection of these units by opening the front cover14. Further, a front cover opening/closing sensor, i.e., second detection portion,15which detects the opening and closing of the front cover14is disposed in the apparatus body10(refer toFIG.4).

As shown inFIG.2, the image forming unit80yincludes a photosensitive drum81, a charge roller82, the developing unit83, and a cleaning unit84. In the first embodiment, the image forming unit80yis attachable to and detachable from the apparatus body10. For example, the image forming unit80ymay be attachable to and detachable from the apparatus body10as a process cartridge including all of these units. On the other hand, it is also acceptable to configure the developing unit83attachable to and detachable from the apparatus body10as a developing cartridge, and configure a drum cartridge, in which the photosensitive drum81, the charge roller82, and the cleaning unit84are integrally included, attachable to and detachable from the apparatus body10independently from the developing cartridge.

The photosensitive drum81is rotated with a drum motor, not shown, and a surface of the photosensitive drum81is charged with the charge roller82at a time of the image formation. A laser beam is irradiated on a charged surface of the photosensitive drum81with the laser scanner43based on the image information, and an electrostatic latent image is born on the surface of the photosensitive drum81. The developing unit83includes a developing sleeve87rotatably disposed in a developing container, and develops to visualize the electrostatic latent image born on the photosensitive drum81with the toner. In the developing unit83, a two-component developer which is a mixture of a nonmagnetic toner and a magnetic carrier is stored, and the toner is supplied from the toner container42filled with the toner.

A toner concentration sensor, i.e., residual quantity detection unit85, (refer toFIG.3) is disposed in a part of a bottom of the developing unit83. The toner concentration sensor85, for example, consists of an inductance sensor, and is capable of detecting a toner concentration inside the developing unit83, and sends a detection result to the control unit70. The toner concentration sensor85is capable of detecting information regarding a residual quantity of the developer in the toner container42. In this embodiment, the toner concentration sensor85is capable of detecting the residual quantity of the developer in the toner container42. Also, the toner concentration sensor85corresponds to an output portion configured to output information of replacing the toner container42. A method to detect the residual quantity of the developer in the toner container42with the toner concentration sensor85will be described later. In a case where the toner concentration detected with the toner concentration sensor85is lower than a target toner concentration, the control unit70drives the toner container drive motor47(refer toFIG.3) and supplies the toner from the toner container42to the developing unit83.

The intermediate transfer unit44is disposed above the image forming units80y,80m,80c, and80k. The intermediate transfer unit44includes a plurality of rollers, such as a drive roller44a, a driven roller, not shown, and a primary transfer roller48, and the intermediate transfer belt44bwhich is wound around these rollers. The primary transfer roller48is disposed to face the photosensitive drum81and abuts on the intermediate transfer belt44b.

The intermediate transfer belt44bis provided with larger than a certain degree of a tensile force also at an idle time, and disposed in a contactable and separable manner with respect to the photosensitive drum81. By applying a positive polarity transfer bias to the intermediate transfer belt44b, respective negative polarity toner images on the photosensitive drums81are successively superimposed on the intermediate transfer belt44bon each other. Thus, the intermediate transfer belt44bis transferred and moved with the toner image of the full color which has been formed by developing the electrostatic latent image born on the surface of the photosensitive drum81.

The secondary transfer unit45includes a secondary transfer internal roller45aand a secondary transfer external roller45b. By applying a secondary transfer bias of a positive polarity to the secondary transfer external roller45b, a full color image formed on the intermediate transfer belt44bis transferred to the sheet S. To be noted, the secondary transfer internal roller45astretches the intermediate transfer belt44bfrom an inside thereof, and the secondary transfer external roller45bis disposed to face the secondary transfer internal roller45aacross the intermediate transfer belt44b.

The fixing unit46includes a fixing roller46aand a press roller46b. By conveying the sheet S between the fixing roller46aand the press roller46bin a sandwiched manner, the toner image transferred to the sheet S is heated and pressed, and fixed to the sheet S. The sheet S fed from the sheet feeding unit30is passed through the secondary transfer unit45and the fixing unit46, and conveyed to a sheet discharge tray50. The sheet discharge tray50is a facedown tray, and stacks the sheet S discharged in an arrow X1 direction from a sheet discharge port10a.

As shown inFIG.3, the control unit70includes a central processing unit (CPU)71, a read only memory (ROM)72which stores a program to control each unit, a random access memory (RAM)73which temporarily stores data, and an input/output circuit (I/O)74to input/output a signal from and to outside. Further, the control unit70includes a pulse width modulation (PWM) unit75, an A/D conversion unit (A/D)76, a motor driving unit, i.e., driver,77to perform a motor drive control, and a timer78to generate a control timing. The I/O74is coupled to the cover opening/closing sensor15of each color, a small door opening/closing sensor, i.e., first detection portion,24, and an attachment detection sensor, i.e., attachment detection unit,25. The PWM unit75is coupled to a solenoid21of each color, and is capable of performing control to disengage a lock of the small door13y(refer toFIG.1) in the closed state. The A/D76converts an analog signal of the detection result from the toner concentration sensor85of each color to a digital signal. The motor driving unit77is coupled to the toner container drive motor47of each color and a developing screw drive motor86of each color. Further, the control unit70is coupled to an upper rank computer, not shown. The control unit70is capable of operating the operation unit11, and based on an instruction from the upper rank computer, not shown, capable of performing a setting change of a printer, and starting an image forming job.

When the image forming job is submitted, the CPU71drives the developing screw drive motor86of each color. Based on information such as the detection result of the toner concentration sensor85of each color, the CPU71drives the toner container drive motor47and supplies the toner to the developing unit83. For example, in a case where a threshold value for a number of times of toner absence is an X time, the control unit70judges that the toner in the toner container42is absent when the detection result of the toner concentration sensor85is smaller than a lower concentration limit y after drivingly rotated the toner container drive motor47the X times. Thus, in a case where, based on the detection result of the toner concentration sensor85and the number of times which the toner container drive motor47has driven, the control unit70judges that the toner is absent in the toner container42, the control unit70, for example, displays a message urging to replace the toner container42on the operation panel11a. Alternatively, the control unit70outputs information to an external computer coupled to the image forming apparatus1, and displays the message urging to replace the toner container42on a monitor of the computer. That is, based on the detection result of the toner concentration sensor85, the control unit70urges a user to replace the toner container42. In this case, in a case where the control unit70detects the opening of the front cover14with the cover opening/closing sensor15, the control unit70opens the small door13ywith an opening mechanism27(refer toFIG.4), described later.

Further, in a case where the attachment detection sensor25is an OFF state, the control unit70judges that the toner container42is not attached. That is, the attachment detection sensor25is capable of detecting an attachment and unattachment of the toner container42to and from the attachment portion12y(refer toFIG.1). In the first embodiment, in a case where the control unit70judges that the toner in any one of the toner containers of yellow, magenta, cyan, and black is absent, the control unit70moves a mode to a color degeneration mode which allows only a monochrome image formation. On the other hand, in a case where the toner in the toner container42for black is judged to be absent, the mode is moved to a toner absent mode where the image formation is not allowed.

Small Door and Front Cover

Next, a configuration of the small door13yand the front cover14will be described in detail usingFIGS.4to7. As shown inFIG.4, in a case where the front cover14is in the closed state (an imaginary line, i.e., two-dot chain line, inFIG.4), a shield portion14adisposed at an upper part of the front cover14is detected with the cover opening/closing sensor15. The cover opening/closing sensor15, for example, consists of a transmissive photosensor having a light emitting component and a photo sensing portion, and is capable of detecting whether or not the front cover14is in the closed state based on whether or not the light from the light emitting component to the photo sensing portion is blocked with the shield portion14aof the front cover14.

The small door13yregulates the attachment and detachment of the toner container42to and from the attachment portion12yby displacing to the closed state. Inside the small door13y, a claw portion13a, which protrudes upward, and a shield portion13bare disposed. In the closed state of the small door13y, the claw portion13ais formed such that a surface on the forward F is upright and a surface on the backward B is inclined. The small door13yis pivotable around a shaft member13ddisposed at a lower position as a center, and always urged in an R1 rotation direction, that is, an opening direction with an urging spring, i.e., urging portion,19consisting of a torsion coil spring.

As shown inFIG.4, when the small door13yis in the open state, the shield portion13bof the small door13yis detected with the small door opening/closing sensor24. The small door opening/closing sensor24, for example, consists of the transmissive photosensor having the light emitting component and the photo sensing portion, and is capable of detecting the opening and closing of the small door13ybased on whether or not the light from the light emitting component to the photo sensing portion is blocked with the shield portion13bof the small door13y.

Inside the apparatus body10, a latch, i.e., locking unit16, is disposed in adjacencies of the claw portion13aof the small door13yin the closed state shown inFIG.4. The latch16includes a lock portion16awhich is capable of engaging with the claw portion13aof the small door13yin the closed state, an engagement portion16bwhich is pivotable with the lock portion16aand engages with a link22coupled to the solenoid21. The latch16is disposed rotatably around a shaft member17disposed in the apparatus body10as a center. The latch16is always urged in an R2 rotation direction, i.e., a direction in which the lock portion16ais engaged with the claw portion13a, with an urging spring18consisting of a return coil spring. Herewith, the latch16is capable to lock the small door13yin the closed state. That is, the small door13yis lockable in the closed state. In the apparatus body10, the solenoid21, as an example of the driving unit, and the link22coupled to the aforementioned solenoid21are disposed. The link22is movable in a front-back direction, and urged to the forward F with a return spring23consisting of a compression coil spring. Further, the link22is disposed such that the link22is capable of engaging with a front portion of the engagement portion16bof the latch16.

In the case of the first embodiment, when the small door13yis in the closed state, the solenoid21is in the OFF state (a non-energized state), and the link22is positioned on a front side by being pressed to the forward F direction with the return spring23. At this time, the latch16is urged with the urging spring18in the R2 rotation direction, and the lock portion16aengages with the claw portion13aso that the small door13ydoes not rotate to open in the R1 rotation direction by being urged with an urging spring19and is locked in the closed state. To be noted, by engaging the upright surface in the front side of the claw portion13awith the lock portion16a, an unexpected opening of the small door13ywith an urging force of the urging spring19is prevented.

As shown inFIG.6, in a case where the solenoid21is in an ON state (an energized state), the link22moves to the backward B against an urging force of the return spring23. Then, a force to pivot the engagement portion16bwhich engages with the link22is provided, the latch16pivots in an opposite direction of the R2 rotation direction against an urging force of the urging spring18. Thus, the lock portion16ais disengaged from the claw portion13a, and the small door13yis automatically opened in the R1 rotation direction with the urging spring19(brought to the open state). That is, the control unit70performs an opening movement of the small door13yby turning the solenoid21to the ON state and disengaging the lock with the latch16.

In the first embodiment, the solenoid21, the urging spring19, and the latch16form the opening mechanism, i.e., opening unit,27. That is, the opening mechanism27is capable of automatically opening the small door13yfrom the closed state to the open state, and, to open the small door13y, the control unit70disengage the lock of the small door13yin the closed state with the latch16.

To be noted, in the first embodiment, a rod coupled to the link22is moved to the backward B by energizing the solenoid21, and, by non-energizing the solenoid21, is moved in an opposite direction to return to an original position by the urging force of the return spring23. However, depending on a form of an engagement of the link22and the lock portion16a, it is acceptable to configure the movement such that the rod is moved to the forward F by energizing the solenoid21and returned with the return spring when the solenoid21is non-energized. Further, in the first embodiment, the urging spring is used to obtain the urging force to open the small door13y, it is not limited to this. For example, it is acceptable to use a motor or a solenoid, or, by positioning a gravity center of the small door13yat an opposite side of the attachment portion12ywith respect to a swing center line of the small door13y, acceptable to configure to open the small door13yunder an own weight thereof.

As described above, after the small door13yhas been brought to the open state by turning the solenoid21to the OFF state, in a case where the user moves the small door13yin the open state in an opposite direction of the R1 rotation direction, the small door13yis closed. At this time, along with a pivot of the small door13y, the claw portion13aof the small door13ypushes up the lock portion16aof the latch16so that the lock portion16apivots against the urging force of the urging spring18. At this point, by engaging an inclined rear surface of the claw portion13awith the lock portion16a, it is possible to easily push up the lock portion16aagainst the urging force of the urging spring18, and engage the claw portion13awith the lock portion16a. When the claw portion13ais pushed into a position where the claw portion13ais engaged with the lock portion16a, the lock portion16ais engaged with the claw portion13awith the urging spring18at a position shown inFIG.4. To be noted, configurations to open and close the small door13yand to lock in the closed state are not limited to the configurations described above, needless to say, it is acceptable to apply other configurations which were hitherto known.

As shown inFIGS.5and7, on the backward B of the attachment portion12y, the attachment detection sensor25and an attachment detection flag26are disposed. The attachment detection sensor25, for example, consists of the transmissive photosensor having the light emitting component and the photo sensing portion. The attachment detection flag26is disposed rotatably around a shaft member26a, which is a rotation shaft extending in the front-back direction, as a center, and capable of moving rotationally between a position to block the attachment detection sensor25, as shown inFIG.5, and a position not to block the attachment detection sensor25, as shown inFIG.7. As shown inFIG.5, when the toner container42is attached, the edge of the toner container42on the backward B pushes up the attachment detection flag26by abutting thereon, and the attachment detection flag26is detected with the attachment detection sensor25. On the other hand, as shown inFIG.7, when the toner container42is moved from an attaching position to a detached position, the attachment detection flag26is released from the edge of the toner container42on the backward B and rotationally moved downward under the own weight thereof, and becomes not detected with the attachment detection sensor25. Therefore, the attachment detection sensor25is capable of detecting whether the toner container42is in an attached state or not in the attached state, that is, in an unattached state based on a detection result of whether or not the light from the light emitting component to the photo sensing portion is blocked with the attachment detection flag26.

Next, in the image forming apparatus1described above, a processing sequence which is performed when the front cover14is opened will be described along a flowchart shown inFIG.8. The CPU71judges whether or not the toner is absent in the toner container42of each color (step S1). At this step, in a case where the detection result of the toner concentration sensor85does not exceed the lower limit of the concentration Y after having rotatably driven the toner container drive motor47the X times continually, the CPU71judges that the toner in the toner container42of the color is absent. The CPU71ends processing in a case where the toner container42is judged to be not absent of the toner (NO at step S1).

In a case where the toner container42of any color is judged to be absent of the toner (YES at step S1), the CPU71starts the processing to replace the toner container42of the color. The CPU71judges with the cover opening/closing sensor15whether or not the front cover14is in the open state (step S2). In a case where the front cover14is judged to be not in the open state (NO at step S2), the CPU71ends the processing. In a case where the front cover14is judged to be in the open state (YES at step S2), the CPU71turns on the solenoid21of the toner container42of a target for replacement corresponding to the color and disengages the lock in the closed state of the small door13ycorresponding to the color (step S3). Thus, by disengaging the lock in the closed state of the small door13ywith the latch16, the small door13yis opened with the urging spring19(step S4). That is, based on the detection result of the toner concentration sensor85, the CPU71opens the small door13yto replace the toner container42attached to the attachment portion12ywhen the front cover14is in the open state. In the first embodiment, only the small door13yof the attachment portion12yto which the toner container42of the target for the replacement is attached is opened.

When the CPU71detects with the small door opening/closing sensor24that the small door13yis in the open state, the CPU71turns off the solenoid21of the toner container42corresponding to the color. Thus, it is possible to reduce unnecessary electricity. Since, at this time, both of the front cover14and the small door13ywhich correspond to the toner container42requiring the replacement are in the open state, the user is able to detach the toner container42and attach the new toner container.

The CPU71judges with the small door opening/closing sensor24whether or not the small door13yis brought from the open state to the closed state (step S5). In a case where the small door13yis judged to be not in the closed state (NO at step S6), the CPU71performs a judgement again (step S5). In a case where the small door13yis judged to be in the closed state (YES at step S5), the CPU71judges with the attachment detection sensor25whether or not the toner container42of the color is unattached (step S6). In a case where the toner container42of the color is judged to be not unattached, that is, attached (NO at step S6), the CPU71ends the processing.

On the other hand, in a case where the toner container42is judged to be unattached (YES at step S6), the CPU71turns on the solenoid21and disengages the lock in the closed state of the small door13ycorresponding to the color (step S7). That is, in a case where the toner container42is detected to be unattached to the attachment portion12ywith the attachment detection sensor25, the CPU71opens the small door13ywith the opening mechanism27when the closed state of the small door13yis detected with the small door opening/closing sensor24after the small door13yhas been opened. As described above, when the solenoid21of the opening mechanism27is turned on to disengage the lock in the closed state of the small door13ywith the latch16, the small door13yis brought to the open state with the urging spring19(step S8). Further, in a case where the small door13yis detected to be in the open state with the small door opening/closing sensor24, the CPU71turns the solenoid21into the OFF state. Herewith, it is possible to reduce the unnecessary electricity. Thus, in a case where the toner container is unattached, by automatically reopening the small door13ywhen the small door13yis closed, it is possible for the user to recognize that the toner container42is unattached.

Further, in a case where the small door13yis closed with the toner container42unattached to the attachment portion12y, it is acceptable to configure the CPU71such that the operation panel11aas the display unit displays the message informing an unattachment of the toner container42to the attachment portion12y. Alternatively, it is acceptable to emit a warning sound from a built-in speaker of the image forming apparatus.

As described above, in the image forming apparatus1of the first embodiment, in a case where the toner container42is detected to be unattached to the attachment portion12ywith the attachment detection sensor25, the control unit70performs the processing as described below. That is, in a case where the small door opening/closing sensor24detects the closed state of the small door13ywith the toner container42unattached, the control unit70brings the small door13yto the open state with the opening mechanism27. Herewith, in a case where, at the replacement of the toner container42, the user has closed the small door13ywithout noticing the unattachment of the toner container42, the small door13yis automatically opened, and the user is able to recognize the unattachment of the toner container42before closing the front cover14. In other words, in a case where the user has closed the small door13yof the attachment portion12ywithout attaching the toner container42, it is possible to prevent a troublesome work, such as, to open the front cover14again. That is, when the toner container42is unattached, it is possible to improve an operability.

Further, in the image forming apparatus1of the first embodiment, in a case where the replacement of the toner container42has become necessary, such as a case where a residual quantity of the developer in the toner container42attached to the attachment portion12yhas been lessened to less than a predetermined quantity, the control unit70is capable of automatically opening the small door13ywith the opening mechanism27. Thus, it is possible to facilitate a replacement work of the toner container42to be carried out by the user. To be noted, in the first embodiment, the small door13yof the target is opened in a case where the front cover14is detected to be in the open state. However, for example, it is acceptable to configure the processing such that, by disengaging the lock of the small door13yof the target in advance even if the front cover14has been closed, the small door13ywith the lock already disengaged is opened when the front cover14is opened.

To be noted, although, in the image forming apparatus1of the first embodiment, the solenoid21is configured to return with the return spring when the electricity is turned off, a configuration of the solenoid is not limited to this. For example, it is acceptable to use a self-holding type solenoid, which does not return to an original position when the electricity is turned off and maintains a position displaced when the electricity was turned on, for the solenoid21. Herewith, for example, in a case where the electricity is turned off while the lock of the small door13yis being disengaged, disengagement of the lock is maintained. In this case, when the small door13yis closed by the user with the lock of the small door13ydisengaged, and the closed state of the small door13yis detected with the small door opening/closing sensor24, the control unit70refers to the attachment detection sensor25. In a case where the attachment detection sensor25detects the unattachment of the toner container42, the control unit70does not turn on the electricity to the solenoid21, and holds the lock of the small door13yin a disengaging state. Further, in a case where the attachment detection sensor25detects an attachment of the toner container42, the control unit70turns on the electricity to the solenoid21, and lock the small door13yin the closed state.

Further, although, in the image forming apparatus1of the first embodiment, the residual quantity of the toner in the toner container42is detected based on the detection result of the toner concentration sensor85, it is not limited to this. For example, it is acceptable to provide a storage container at a toner hopper to store the toner discharged from the toner container42, and dispose a residual quantity detection sensor, i.e., the residual quantity detection unit, on a wall of the storage container. This residual quantity detection sensor is, for example, a piezo type sensor, capable of detecting information regarding the residual quantity of the developer in the toner container42by detecting a height of a toner powder using a change in an output voltage due to presence and absence of the toner in adjacencies of a sensor surface.

Second Embodiment

Next, a second embodiment of the present disclosure will be described in detail with reference toFIGS.9to22. An electric drive motor is used as a mechanism to open a small door, and the second embodiment is different from the first embodiment at this point.

General Configuration of Image Forming Apparatus

FIG.9is a cross-sectional view of an image forming apparatus200which is an example of the second embodiment of the present disclosure. The second embodiment is a color image forming unit using an electrophotographic system, and recently an intermediate transfer tandem type, in which image forming units of 4 colors are arranged on an intermediate transfer belt, becomes a mainstream because of advantages in adaptability to various sheet materials and good printing productivity. In the second embodiment, an image is formed with 4 colors of yellow (Y), cyan (C), magenta (M), and black (B). Needless to say, a number of the colors are not limited to 4, and a sequence of the colors is not limited to this. An image forming process to form an image on a sheet with the image forming apparatus which is an example of the second embodiment will be described below.

A sheet S is stored in a sheet storage portion162in a stacked form, and fed with a sheet feeding unit163in a timing synchronizing with an image formation. The sheet S sent out with the sheet feeding unit163passes through a sheet conveyance path164, and is conveyed to a registration roller165. At the registration roller165, having corrected a sheet skew of the sheet S conveyed from the sheet storage portion162, the sheet S is conveyed to a secondary transfer portion in a predetermined timing synchronizing with a toner image formed on an intermediate transfer belt161. The secondary transfer portion is a toner image transfer nip portion to transfer a toner image onto the sheet S, and formed with a secondary transfer internal roller166and a secondary transfer external roller167facing each other. The secondary transfer portion transfers the toner image formed on the intermediate transfer belt161onto the sheet S by providing a predetermined pressure and an electrostatic load bias. The image forming process to form the toner image on the intermediate transfer belt161will be described next.

An image forming unit600is principally configured with such as a photosensitive member601, a charge roller602as a charge member, a developing unit603, a primary transfer roller604as a primary transfer member, and a photosensitive member cleaner605. Further, a similar configuration is applied to the 4 colors of yellow (Y), cyan (C), magenta (M), and black (B), and the image forming unit600of each color is arranged in parallel with each other. To be noted, the image forming units600are similar in a structure except for a difference in the color of a developer. Therefore, the image forming unit600for black will be described below as a representative, and descriptions of other image forming units are omitted herein. A toner supply apparatus606is disposed above the image forming unit600, and a toner container110is provided as a developer accommodating container corresponding to each color of the image forming units. The toner supply apparatus606will be described later in detail.

Regarding the image forming process, first, an electrostatic latent image is born on a surface of the photosensitive member601based on a signal of image information sent from an exposing unit609. To be noted, the surface of the photosensitive member601has been uniformly charged with the charge roller602in advance. Then, the electrostatic latent image born on the photosensitive member601is developed with the toner in the developing unit603, and visualized as the toner image on the photosensitive member601. Thereafter, by providing a predetermined pressure and an electrostatic load bias with the primary transfer roller604, the toner image is transferred onto the intermediate transfer belt161. A transfer residual toner barely remained on the photosensitive member601is recovered with the photosensitive member cleaner605. Further, the toner consumed with the developing unit603is supplied from a toner container110, and the image forming apparatus200is prepared for a next image formation again. The intermediate transfer belt161is stretched with rollers, such as driven rollers168,169, a tension roller170, and the secondary transfer internal roller166, drivingly conveyed in an arrow X2 direction inFIG.9. The image forming process with each of the image forming units of colors Y, M, C, and K described above is performed in parallel with each other in a timing to superimpose the toner image on the toner image of an upstream color on the intermediate transfer belt161. Therefore, the toner image of a full color is eventually formed on the intermediate transfer belt161, and conveyed to the secondary transfer portion.

Along the process described above, the full color toner image is secondarily transferred to the sheet S at the secondary transfer portion. Thereafter, the sheet S is conveyed to a fixing unit171. The fixing unit171fixes the toner image on the sheet S with a predetermined pressure force with such as rollers or belts facing each other and adding a heat with a heat source such as, generally, a heater and fusion bonding the toner image. The sheet S given a fixing process in the fixing unit171is discharged to a sheet discharge tray211, and an image forming operation is completed.

Toner Supply Apparatus

FIGS.10A and10Bshow an external view of the image forming apparatus200, andFIGS.11A and11Bshow a perspective view of the toner supply apparatus606. As shown inFIGS.10A and10B, on a front side of the image forming apparatus200, a front cover270which is openable and closable with hands is disposed, and by opening the front cover270the toner supply apparatus606is accessible (refer toFIG.10B). The front cover270is an example of a second cover. To be noted, the toner supply apparatus606is provided with a same structure for each of 4 colors of yellow (Y), magenta (M), cyan (C), and black (K), and disposed in parallel with each other, and the toner supply apparatus606of each color has a same structure except for a difference in a developing color. That is, each constituent of the toner supply apparatus606is disposed plurally in accordance with the developing colors.

As shown inFIGS.11A and11B, for example, the toner supply apparatus606for black is configured as described below. That is, the toner supply apparatus606includes the toner container110which is attachable and detachable, a toner cartridge tray221, a toner cartridge driving device205, a small door213, a locking device206, an internal cover224, and an attachment portion212. The toner cartridge tray221is capable of guiding the toner container110to the image forming apparatus200at an attachment of the toner container110and holding the toner container110after attached. The toner cartridge driving device205is capable of drivingly rotating the toner container110, and, by rotating, the toner container110is capable of conveying (supplying) the toner in the toner container110to the developing unit603(refer toFIG.9).

As shown inFIG.11B, an attachment/detachment port224a, which is an example of an opening portion corresponding to each color of the toner cartridge, is provided in the internal cover224, and the attachment and detachment of the toner container110to and from the attachment portion212is performed in a front-back direction of the forward F and the backward B through the attachment/detachment port224a. To be noted,FIG.11Bshows a case of the toner container110of black, and cases of toner cartridges of other colors are similar to this. The small door213is an example of a first cover and the door used for a replacement of the toner cartridge, and the door to open and close the attachment/detachment port224a, and the attachment and detachment of the toner container110is possible only when the small door213is opened. The locking device206, which is an example of the opening portion, is capable of performing a lock of the small door213in the closed state and disengaging the lock, and receives a drive force to disengage the lock from the toner cartridge driving device205. The small door213is disposed immediately inside the front cover270, and an opening and closing operation of the small door213is allowed only when the front cover270is in the open state. An opening and closing of the front cover270is detected with an opening/closing detection sensor271(refer toFIG.10B), which is an example of a second opening/closing detection unit. Hereinafter, a detail configuration of each constituent of the toner supply apparatus606will be described.

Toner Cartridge Driving Device

As shown inFIGS.12and13, the toner cartridge driving device205includes such as a base251, a driving motor252, a pinion gear253, a speed reduction gear254, a transmission gear255, a transmission shaft256, a driving gear257, a small door opening/closing sensor258. The driving motor252consists of an electric motor, which is an example of a driving unit, and is fixed to the base251, and the pinion gear253is pressed into a rotation shaft of the driving motor252. The speed reduction gear254is rotatably supported with respect to the base251, and disposed at a position where the speed reduction gear254engages with the pinion gear253and the transmission gear255. Herewith, a driving force is transmitted from the pinion gear253to the transmission gear255. The transmission shaft256is rotatably supported with the base251, and fixes each of the transmission gear255and the driving gear257to a different edge thereof, and couples the transmission gear255and the driving gear257together. Incidentally, the transmission shaft256is disposed along the front-back direction. Further, the driving gear257is disposed upstream of the transmission gear255and the driving motor252in the front-back direction, that is, on the forward F.

The small door opening/closing sensor258(refer toFIG.13) is, for example, an optical sensor having a light emitting component and a photo sensing portion to receive a light from the light emitting component. The small door opening/closing sensor258is capable of detecting a position of a shaft262, described later, by detecting whether or not the shaft262blocks the light between the light emitting component and the photo sensing portion (refer toFIGS.15A to15C). The small door opening/closing sensor258is the sensor which detects an opening and closing of the small door213by detecting the position of the shaft262in an axial direction, and will be described in detail in a description of a lock mechanism described later.

A rotary drive of the driving motor252is transmitted to the driving gear257via the pinion gear253, the speed reduction gear254, the transmission gear255, and the transmission shaft256. In a case where the toner container110is attached to the attachment portion212A, a cartridge gear110aand the driving gear257included in the toner container110are disposed at a position to engage each other, and the toner container110is rotated by a rotation of the driving gear257. To be noted, a rotation direction of the driving gear257is such that the driving gear257rotates the toner container110in an R3 rotation direction, which is a first rotation direction, to supply the toner to the developing unit603. That is, the driving gear257is coupled to the driving motor252, and, by rotating the toner container110fitted in the attachment portion212in the R3 rotation direction, is capable of feeding the developer from the toner container110. An attachment detection sensor240, which is an example of an attachment detection unit, blocks a light path of the sensor in a case where the toner container110is attached to the toner cartridge tray221. Herewith, it is possible to detect whether or not the toner container110is attached to the toner supply apparatus606.

Small Door

Next, usingFIGS.14to15C, the small door213will be described. The small door213includes a door body233, a pair of center holes234, a claw portion235, and a rotation stopper portion236. The pair of center holes234are disposed on a left and right as a pair, and rotatably engaged with a rotation shaft237included in the internal cover224, and herewith the small door213is rotatably supported with the internal cover224. To be noted, in a state where the small door213stands upright (refer toFIG.14), a weight center of the small door213is on the forward F with respect to a center line connecting the pair of the center holes234. Accordingly, the small door213is rotatably supported with respect to the pair of the center holes234, and in a case where an external force is absent, falls to the forward F under its own weight thereof and is opened. Thus, it is possible to eliminate a need to provide a dedicated spring member to open the small door213.

As shown inFIG.15A, when the small door213is in a closed state, the claw portion235engages with a locking portion260don the forward F of a latch260, described later. Therefore, the small door213is held in the closed state without swinging toward the internal cover224(refer toFIG.11A). To be noted, the latch260is a component constituting the lock device206, and will be described in detail in a description of the locking device206. As shown inFIG.15B, when the latch260swings and an engagement of the locking portion260dof the latch260with the claw portion235is disengaged, the small door213becomes capable of swinging. At this time, since the weight center of the small door213is on a side of opening the small door213, when the engagement of the latch260with the claw portion235is disengaged, the small door213swings in the opening direction under the own weight thereof. As shown inFIG.15C, the small door213swings until reaching to a position where the rotation stopper portion236abuts on a stopper238disposed in the internal cover224, and a posture of the small door213at a time of abutting is defined. In this state, the small door213is maximally opened.

Lock Device

Next, with referring toFIGS.16to19B, the locking device206will be described. As shown inFIGS.16and17, the locking device206includes the latch260, a base261, the shaft262, a latch driving unit263, a latch spring264, a shaft spring, i.e., shaft urging portion,265, a one-way gear266(refer toFIG.15A). The shaft, i.e., rotation shaft,262, which is rotatable by a driving force from the driving motor252, and the latch driving unit, i.e., sleeve,263of a cylindrical shape, which is slidably disposed on a circumference of the shaft262, forms a transmission unit, which is rotatable by a driving force from the driving motor252. Further, the transmission unit is disposed such that a direction of a rotational axis thereof is along the front-back direction which is the insert direction to fit the toner container110into the attachment portion212. To be noted, the base261is fixed to an upper portion of the internal cover224(refer toFIG.11A), but an illustration of the base261is omitted inFIG.17.

A longitudinal direction of the latch260, as a locking unit, is the front-back direction, and the latch260is supported approximately at a center in the front-back direction with a swing shaft267in a manner capable of swinging with respect to the base261. The latch260includes a swing hole260asupported with the swing shaft267in a manner capable of swinging, an engaged portion260bdisposed on the backward B, and a hook260cdisposed on the forward F. A center line of the swing shaft267is along a left to right direction of an apparatus body210, and the swing shaft267is fixed to the base261. That is, the swing shaft267is disposed between the locking portion260dand the engaged portion260b, and makes the latch260capable to swing around a rotational axis direction perpendicularly intersecting with a rotational axis direction of the shaft262, which is the front-back direction. To be noted, the latch260and the swing shaft267form a locking portion.

The latch260is supported with the base261in a manner capable of swinging, and the hook260cis stretched with the latch spring264which consists of a tension spring and works as a locking urging portion. A lower and an upper edge of the latch spring264are respectively fixed to the hook260cand the base261, and the latch spring264urges the backward B of the latch260upward.

The shaft262is supported rotatably and movably along a rotational axis direction thereof with the base261in adjacencies of an edge on the forward F. In adjacencies of an edge on the backward B of the shaft262, the one-way gear266(refer toFIG.15A) is fixed. The shaft spring265consists of a compression spring, and an edge on the forward F thereof abuts on a flange portion262afixed to the shaft262, and an edge of the shaft spring265on the backward B abuts on the base261(refer toFIG.16). Herewith, the shaft spring265urges the shaft262toward the small door213along the rotation direction of the shaft262, and with respect to the base261the shaft262is always urged toward the forward F.

The latch driving unit263having a shape of the sleeve is slidably held on the circumference of the shaft262, and is disposed such that a position thereof is fixed in an axial direction with respect to the base261. As shown inFIG.18, the latch driving unit263has an approximately cylindrical shape, and held by the shaft262passing through inside the latch driving unit263of the cylinder shape. On a circumferential surface of the shaft262, an engagement protrusion, i.e., first protrusion,262bis disposed. On an inner circumferential surface of the latch driving unit263an engaged protrusion, i.e., second protrusion,263a, which is capable to engage with the engagement protrusion262bin a rotation direction, is disposed (refer toFIG.19A), and on a circumferential surface of the latch driving unit263an engagement portion263bis disposed. The engagement portion263bprotrudes in a radial direction on a circumference of the latch driving unit263.

As shown inFIG.19B, shapes of the engagement protrusion262band the engaged protrusion263aare similar to shapes of an internal tooth and external tooth of a gear, and by engaging each other a rotary drive of the shaft262is transmitted to the latch driving unit263in synchronizing each other. To be noted, the shaft262is slidable to the latch driving unit263in the axial direction thereof. Therefore, a transmission of the rotary drive is limited to a case where the engagement protrusion262band the engaged protrusion263aoverlap each other at least partially, such as a case of the small door213being in the closed state (refer toFIG.15A). In a case where the engagement protrusion262band the engaged protrusion263ado not overlap each other entirely, such as a case of the small door213being in the open state (refer toFIG.15B), the rotary drive is not transmitted. That is, the latch driving unit263is movable to a first position (refer toFIG.15A) and a second position (refer toFIG.15B) along the rotational axis direction. The first position is a position where the engagement protrusion262band the engaged protrusion263aengage each other in the rotation direction. On the other hand, the second position is the position where the engagement protrusion262band the engaged protrusion263ado not engage each other in the rotation direction. The shaft262is configured to relatively move in the rotational axis direction of the shaft262with respect to the latch driving unit263, and, by a relative movement in the rotational axis direction, relative positions of the shaft262and the latch driving unit263is switched between an engaging position where the shaft262and the latch driving unit263engage each other and rotate integrally and a disengaging position where the shaft262and the latch driving unit263does not engage each other and rotate idly.

Further, in a case where the small door213is in the closed state, the latch driving unit263is at the first position (refer toFIG.15A), and in a case where the small door213is in the open state, the latch driving unit263is at the second position (refer toFIGS.15B and15C). To be noted, when the latch driving unit263moves from the second position to the first position in the axial direction, there is a possibility that the engagement protrusion262band the engaged protrusion263aabut each other in the axial direction and prevent a movement of the latch driving unit263. Therefore, in this embodiment, a taper is formed on a facing surface of an at least one of the engagement protrusion262band the engaged protrusion263ain the axial direction so that the engagement protrusion262band the engaged protrusion263acircumvent each other in the rotational direction when the engagement protrusion262band the engaged protrusion263aabut each other.

Assembly of the lock device206to the apparatus body210is performed such that the base261is fixed to the internal cover224, and the edge of the shaft262on the backward B is held with the base261rotatably and movably in the axial direction. As shown inFIGS.15A to15C, the one-way gear266always engages with the driving gear257regardless of a position of the shaft262in the axial direction. The edge of the shaft262on the backward B is, by a movement of the shaft262in the axial direction, capable of displacing between a position, where the shaft262blocks a detection area of the small door opening/closing sensor258(refer toFIG.15A), and a position, where the shaft262retreats from the detection area of the small door opening/closing sensor258(refer toFIG.15B).

As shown inFIG.13, the one-way gear266includes a driven gear266awhich engages with the driving gear257, and a one-way clutch266bfixed to the shaft262. In a case where the driving gear257rotates in the R3 rotation direction, the driven gear266ais idly rotated around the shaft262with this one-way clutch266b, and in a case where the driving gear257rotates in an R4 rotation direction, which is a second rotation direction opposite to the R3 rotation direction, the driven gear266atransmits the rotary drive to the shaft262with the one-way clutch266b, and the shaft262is driven. That is, the one-way clutch266bis interposed between the driven gear266aand the shaft262, and disposed on a power transmission path between the driving motor252and the toner container42. To be noted, since the toner is supplied from the toner container110to the developing unit603when the driving gear257is rotated in the R3 rotation direction, the one-way gear266idly rotates when the toner is supplied from the toner container110to the developing unit603. Further, when the driving gear257is rotated in the R4 rotation direction which is opposite to the rotation direction of supplying the toner, the rotary drive is transmitted to the shaft262and the lock in the closed state of the small door213is disengaged.

Opening/Closing Movement of Small Door

Next, a series of movements of the locking device206to open and close the small door213will be described with referring toFIGS.15A to15C. As shown inFIG.15A, when the small door213is in the closed state, since the claw portion235disposed in the small door213is held with the locking portion260dof the latch260, the small door213does not swing and is held in the closed state. That is, the latch260is capable of holding the small door213in the closed state, and the locking portion260dis capable of engaging with the small door213, and lock the small door213in the closed state. A position of the latch260at this time is an original position, and the latch260is held at the original position unless an external force is provided since the latch260is urged in a direction to lock the small door213with the latch spring264.

The shaft262is urged to the forward F of the apparatus body210with the shaft spring265, and the position of the shaft262in the axial direction is defined by a front edge262cof the shaft262abutting on the small door213in the closed state. That is, the shaft spring265urges the shaft262toward the small door213along the rotational axis direction. At this time, the edge of the shaft262on the backward B is at a position of blocking the detection area of the small door opening/closing sensor258, and a control unit400judges that the small door213is in the closed state. Further, the latch driving unit263is at the first position in the axial direction, and the engagement protrusion262bof the shaft262and the engaged protrusion263aof the latch driving unit263are at the engagement position in the rotation direction (refer toFIG.18). Therefore, the shaft262and the latch driving unit263are at the relative positions where it is possible to transmit the driving force in the rotation direction by synchronizing each other.

As shown inFIG.15B, for opening the small door213, the driving gear257is rotated in the R4 rotation direction by driving the driving motor252(refer toFIG.13). By the rotation of the driving gear257, the rotary drive is transmitted to the one-way gear266and the shaft262, and the shaft262is rotated in an R5 rotation direction. At this time, since the shaft262and the latch driving unit263are at the relative positions where the rotary drive is transmitted, the latch driving unit263is also rotated in the R5 rotation direction. By the rotation of the latch driving unit263, the engagement portion263bpushes down the engaged portion260bof the latch260, and the latch260swings in an R6 rotation direction, and the claw portion235of the small door213are disengaged from the locking portion260dof the latch260. That is, the engagement portion263band the engaged portion260bengage each other by the rotation of the shaft262and the latch driving unit263. Thus, a locked state where the small door213is locked in the closed state (refer toFIG.15A) is switched to an unlocked state where the closed state of the small door213is unlocked (refer toFIGS.15B and15C). Thus, the small door213starts to swing toward an opening direction under the own weight thereof.

Since a thrust position regulation of the front edge262cby the small door213is removed, the shaft262moves to the forward F in the rotational axis direction with the shaft spring265. That is, when the engagement portion263bswitches the latch260to the unlocked state, the small door213is pressed and brought to the open state with the shaft spring265. To be noted, a force of the shaft spring265to move the shaft262along the axial direction provides an auxiliary force to swing the small door213. That is, although the small door213swings under the own weight thereof, for example, there is a possibility that a foreign material is stuck in a moving part of the small door213and the small door213becomes difficult to swing under the own weight thereof. Even in these cases, since the force of the shaft spring265to move the shaft262along the axial direction works as a force to press the small door213in the opening direction thereof, it is possible to securely open the small door213. Further, since the edge of the shaft262on the backward B is at a position separated from the detection area of the small door opening/closing sensor258, the control unit judges that the small door213is in the open state.

Further, as shown inFIG.15C, when the small door213is maximally opened, the shaft262which is removed of the positional regulation by the small door213moves in the axial direction until the flange portion262aof the shaft262abuts on a regulation portion261adisposed at the base261. Thus, a position of the shaft262in the open state of the small door213is defined. At this time, since the latch driving unit263is at the second position in the axial direction and the engagement protrusion262b, disposed at the shaft262, and the engaged protrusion263a, disposed at the latch driving unit263, are out of alignment in the axial direction each other, the rotary drive is not transmitted. Since the latch driving unit263becomes rotatable without a driving force from the shaft262and a force to push down the engaged portion260bof the latch260with the engagement portion263bof the latch driving unit263is removed, the latch260returns to the original position with the latch spring264. Along with the return of the latch260to the original position, the engaged portion260bof the latch260pushes up the engagement portion263bof the latch driving unit263. Further, since the edge of the shaft262on the backward B is at a position separated from the detection area of the small door opening/closing sensor258, the control unit400judges that the small door213is in the open state. As described above, since the small door213to which the toner container110of the target for the replacement is attached is automatically opened, it is possible for the user to identify the toner container110of the target without a mistake.

At a time of returning the small door213in the open state to the closed state again, the user closes the small door213in the open state with hands. At this time, the front edge262cof the shaft262is pushed into the backward B with the small door213, and the claw portion235pushes up the locking portion260dof the latch260so that the claw portion235is engaged with the locking portion260dand returns to a state shown inFIG.15A. Since the edge of the shaft262on the backward B moves to the position to block the detection area of the small door opening/closing sensor258, the control unit400judges that the small door213is in the closed state. At this point, since the shaft262and the latch driving unit263are different components and capable to perform relative movements in the axial direction from each other, the latch driving unit263barely moves in the axial direction. Therefore, regardless of a position of the shaft262in the axial direction and the open or closed state of the small door213, relative positions of the engaged portion260bof the latch260and the engagement portion263bof the latch driving unit263in the axial direction barely change. Accordingly, it is possible to obviate an interruption of a swinging movement of the small door213, which may be caused by an abutment of the engaged portion260bof the latch260and the engagement portion263bof the latch driving unit263in the axial direction when the small door213is brought from the open state to the closed state.

As described above, it is possible to control the opening movement of the small door213using a same driving source as the toner container110. To be noted, when the toner container110is rotated to perform a normal supply movement, the small door213is not affected since the driving gear257is rotated in the R3 rotation direction shown inFIG.13and a driving force is not transmitted to the shaft262.

Next, a control configuration of the toner supply apparatus606will be described.FIG.20is a block diagram showing the control configuration to control a movement of the toner supply apparatus606. As shown inFIG.20, the control unit400includes a CPU401, a ROM402, a RAM403, and an electrically erasable programmable read-only memory (EEPROM)404. The ROM402stores a control program to control a whole of the image forming apparatus200. The RAM403is a volatile memory device used for a workspace of the CPU401and a temporary storage of various data such as image data. The EEPROM404is a nonvolatile memory device to store various data such as a residual quantity of the toner in the developing unit603.

The CPU401controls the whole of the image forming apparatus200by executing the control program, which the CPU401reads out and sends to the RAM403, stored in the ROM402. The CPU401is electrically coupled to driving units such as a system controller410, a front cover control unit421, a toner supply control unit422, and a developing unit control unit423via a control block or various drivers, not shown. The system controller410controls a display panel273which is an example of a display unit. The front cover control unit421detects and controls an opening and closing of the front cover270. The toner supply control unit422controls a toner supply movement and an opening and closing of the small door213. The developing unit control unit423controls such as a toner concentration in the developing unit603. In this embodiment, a toner concentration sensor631consisting of, for example, an inductance sensor is disposed as an example of a residual quantity detection unit, and the toner concentration sensor631is capable of detecting the toner concentration in the developing unit603, and the detection result thereof is sent to the developing unit control unit423.

Flow of Movement of Small Door

Next, a control flow of a lock disengagement movement of the small door213will be described with reference to a flowchart illustrating a movement of the small door shown inFIG.21. The CPU401judges whether or not the toner is absent in the toner container110of each color (step S11). For example, by estimating the toner concentration in the toner container110from the toner concentration in the developing unit603detected with the toner concentration sensor631, the CPU401judges whether or not the toner is absent in the toner container110. However, it is not limited to this method. For example, it is acceptable to measure a weight of the toner container110, or acceptable to apply a method to estimate the residual quantity of the toner from a quantity per supply and number of times supplied. The CPU401ends processing when the toner in the toner container110is judged to be not absent (No at step S11).

In a case where the toner in the toner container110of any color is judged to be absent (YES at step S11), the CPU401starts the processing to replace the toner container110of the corresponding color. The CPU401judges with the cover opening/closing detection sensor271whether or not the front cover270is in the open state (step S12). In a case where the front cover270is judged to be not in the open state (NO at step S12), the CPU401ends the processing. In a case where the front cover270is judged to be in the open state (YES at step S12), the CPU401rotates the driving motor252of a station (color) corresponding to the toner container110of the target in an opposite direction (step S13). To be noted, a rotation direction in which the toner container110rotates in a normal toner supply operation is defined as a positive rotation, and a rotation direction to bring the small door213to the open state is defined as an inverse rotation.

The CPU401monitors the small door opening/closing sensor258of the target station for the replacement, and judges whether or not the small door213is brought from the closed state to the open state (step S14). In a case where the CPU401judges that the small door213is not in the open state (NO at step S14), the CPU401performs the judgement again (step S14). In a case where the CPU401judges that the small door213is in the open state (YES at step S14), the CPU401stops the driving motor252and ends the processing (step S15). Since, by the processing described above, the small door213to which the toner container110of the target for the replacement is attached is automatically opened, it is possible for the user to identify the target toner container without a mistake.

Next, a movement flow to identify a state of the attachment of the toner container110will be described with reference to a flowchart illustrating a movement for identification of a toner container attachment shown inFIG.22. The CPU401monitors the small door opening/closing sensor258of the target station for the identification, and judges whether or not the small door213is brought from the open state to the closed state (step S21). In a case where the CPU401judges that the small door213is not brought to the closed state (NO at step S21), the CPU401performs the judgement again (step S21). In a case where the CPU401judges that the small door213is brought to the closed state (YES at step S21), the CPU401judges whether or not the toner container110is unattached (step S22). In a case where the CPU401judges that the toner container110is not unattached (NO at step S22), the CPU401ends the processing.

In a case where the CPU401judges that the toner container110is unattached (YES at step S22), the CPU401judges with an opening/closing detection sensor271whether or not the front cover270is in the open state (step S23). In a case where the CPU401judges that the front cover270is in the open state (YES at step S23), the CPU401inversely rotates the driving motor252corresponding to the target station (step S24). The CPU401monitors the small door opening/closing sensor258of the target station for the replacement, and judges whether or not the small door213is brought from the closed state to the open state (step S25). In a case where the CPU401judges that the small door213is not brought to the open state (NO at step S25), the CPU401performs the judgement again (step S25). In a case where the CPU401judges that the small door213is brought to the open state (YES at step S25), the CPU401stops the driving motor252and ends the processing (step S26).

As described above, in a case where the user closes the small door213without attaching the toner container110at the replacement of the toner container110by a mistake, an unattachment of the toner container110is shortly detected, and once detected the small door213is immediately opened. Thus, it is possible for the user to return to an attachment work of the toner container110again without a waiting time. To be noted, as described above, when the toner container110is judged to be unattached, the small door213is immediately opened. Therefore, it barely occurs that the small door213is in the closed state with the toner container110unattached and also with the front cover270being in the closed state (NO at step S23). However, in a case where the aforementioned state occurs, for example, by closing the small door213and the front cover270at the same time, it is not possible to open the small door213. Supposing that it is possible to open the small door213inside the front cover270, it is not possible for the user to recognize that the small door213is in the open state since the front cover270is closed. Therefore, in this embodiment, in a case where the toner container110is unattached with the small door213and the front cover270being in the closed state, a message to inform the unattachment of the toner container110is displayed (step S27) on the display panel273(refer toFIG.10A). Herewith, it is possible to inform the user of the state described above.

As described above, in the image forming apparatus200of the second embodiment, in a case where the user closes the small door213without noticing the unattachment of the toner container110at the replacement of the toner container110, the small door213is automatically opened. Therefore, it is possible for the user to recognize the unattachment of the toner container110before closing the front cover270. Herewith, in a case where the small door213is closed without attaching the toner container110, it is possible to prevent a complicated work such as to open the front cover270again after closed the front cover270without noticing the unattachment, and an operability is improved at a time when the toner container110is unattached.

Further, in this embodiment, the mechanism to use the driving motor252which is a driving source to supply the toner from the toner container110is applied to disengage the lock in the closed state of the small door213. Therefore, it is possible to prevent an increase in high price components of the driving unit, and, with a simple configuration and low cost, it is possible to achieve to perform the disengagement of the lock in a case where the small door213is locked in the closed state.

Third Embodiment

Next, a third embodiment of the present disclosure will be described in detail with referring toFIGS.23and24. In the third embodiment, in a case where the small door213is closed a plurality of times, the small door213is held in the closed state, and the third embodiment is different from the second embodiment at this point. To be noted, descriptions overlapping with the second embodiment described above will be omitted herein by putting a same mark as in the second embodiment.

FIGS.23and24are flowcharts showing a sequence of the processing to replace the toner container110in the third embodiment. In the control flow of the third embodiment, the CPU401defines a repeat count number N, and at a start of the flow N is set at zero (step S31). The CPU401monitors the small door opening/closing sensor258of the target station, and judges whether the small door213is brought from the open state to the closed state (step S32). In a case where the CPU401judges that the small door213is not in the closed state (NO at step S32), the CPU401performs the judgement again. In a case where the CPU401judges that the small door213is in the closed state (YES at step S32), the CPU401judges whether or not the toner container110is unattached (step S33). In a case where the CPU401judges that the toner container110is not unattached (NO at step S33), the CPU401ends the processing.

In a case where the CPU401judges that the toner container110is unattached (YES at step S33), the CPU401judges with the opening/closing detection sensor271whether or not the front cover270is in the open state (step S34). In a case where the CPU401judges with the opening/closing detection sensor271that the front cover270is not in the open state (NO at step S34), the CPU401displays the message informing the unattachment of the toner container110on the display panel273and ends the processing (step S35). In a case where the CPU401judges with the opening/closing detection sensor271that the front cover270is in the open state (YES at step S34), the CPU401judges whether or not the repeat count number is larger than a threshold value which is one (step S36). To be noted, although the threshold value of the repeat count number is set at one in this embodiment, it is not limited to this, and acceptable to set appropriately.

In a case where the CPU401judges that the repeat count number N is not greater than 1 (NO at step S36), the CPU401monitors the small door opening/closing sensor258of the target station, and judges whether or not the small door213is brought from the closed state to the open state (step S38). In a case where the CPU401judges that the small door213is not brought to the open state (NO at step S38), the CPU401performs the judgement again (step S38). In a case where the CPU401judges that the small door213is brought to the open state (YES at step S38), the CPU401stops the driving motor252(step S37). The CPU401count up the repeat count number N by 1 (step S40), and returns to the step S32. Having returned to the step S32, unless proceeding to NO at the step S33or S34, the CPU401repeatedly returns to a branch step of the step S36, where the processing is branched based on the repeat count number N, with counting up the repeat count number N by 1 each time. The flow described above is repeated until the repeat count number N exceeds the threshold value.

In a case where the repeat count number N exceeds the threshold value (YES at step S36), the CPU401judges that the toner container110is unattached with the small door213being in the closed state. That is, although the toner container110is unattached and the small door213is in the closed state, in this condition the small door213is not brought to the open state. Thereafter, the CPU401judges with the opening/closing detection sensor271whether or not the front cover270is in the open state (step S41). In a case where the CPU401judges that the front cover270is not in the open state (NO at step S41), the CPU401performs the judgement again (step S41). In a case where the CPU401judges that the front cover270is brought to the open state (YES at step S41), the CPU401displays the message informing the unattachment of the toner container110(step S35) on the display panel273, and ends the processing.

Accordingly, in this embodiment, the opening and closing of the small door213changes in a sequence of the opening, closing, and opening when N is equal to 0, and in a sequence of the opening, closing, and opening when N is equal to 1. When N becomes equal to 2, the opening and closing of the small door213starts with the opening and then changes to the closing. At this time, the CPU401holds the small door213in the closed state. Therefore, in a case where the CPU401detects that the small door213is in the closed state after twice repeated a switch between the open state and the closed state, the CPU401holds the small door213in the closed state. That is, in a case where the CPU401detects that the small door213is in the closed state after repeating the switch between the open state and the closed state, as an example of predetermined times, 4 times, the CPU401holds the small door213in the closed state.

In the above configuration, in a case where a movement to close the small door213is carried out a plurality of times (3 times in a case of this embodiment) with the toner container110unattached, the CPU401judges that the toner container110is intentionally unattached, and holds the small door213in the closed state. Herewith, it is possible to perform a recovery work which is required when the user closes the small door213with the toner container unattached by a mistake. Further, it is possible to intentionally hold the toner container110unattached in cases of such as moving the apparatus body210of the image forming apparatus200and using the image forming apparatus200in a color degeneration mode (such as monochrome only mode).

As described above, the image forming apparatus200of the third embodiment is able to address a case where the user wants to intentionally hold the toner container110unattached.

The present disclosure improves an operability at a time when the accommodating container of the developer is unattached.

Other Embodiments

This application claims the benefit of Japanese Patent Application No. 2019-120819, filed Jun. 28, 2019 and No. 2020-070947, filed Apr. 10, 2020 which are hereby incorporated by reference herein in their entirety.