Image forming apparatus

An image forming device includes: a developing device; a first toner container; a second toner container; a first vertical transport part; a second vertical transport part; a first horizontal transport part; a second horizontal transport part; a third horizontal transport part; a third vertical transport part, a counting unit; and a consumption amount calculation unit. The consumption amount calculation unit, in accordance with a rotation time accumulated by the counting unit, calculates a flow rate of toner flowing in the third horizontal transport part in each of the first supply state and the second supply state, and thereby calculates a toner consumption amount of each of the first toner container and the second toner container.

INCORPORATION BY REFERENCE

This application is based on Japanese Patent Application Serial No. 2018-050717 filed with the Japan Patent Office on Mar. 19, 2018, the contents of which are hereby incorporated by reference.

BACKGROUND

The present disclosure relates to an image forming device for forming an image on a sheet.

Conventionally, an image forming device such as a printer or a copier employing the electrophotographic method includes: a photoreceptor drum that carries an electrostatic latent image; a developing device that supplies toner to the photoreceptor drum and visualizes the electrostatic latent image into a toner image; and a transfer device that transfers the toner image from the photoreceptor drum onto a sheet.

Further, an image forming device is known which has a plurality of developing devices in correspondence to color toners of respective colors and in which, for each developing device, two toner containers for supplying supplement toner to the developing device are disposed. Even when one of the toner containers becomes empty, toner from the other toner container can be supplied. Hence, the time over which the image forming device is forced to stop (print incapable time) is shortened. Particularly when a print job involving a large number of sheets to be printed is executed, a situation in which the job is interrupted halfway due to toner shortage can be prevented.

Also, a technique is known of calculating a toner consumption amount of a toner container based on a rotation count of a transport screw arranged in a transport path between the toner container and a developing device.

SUMMARY

An image forming device according to one aspect of the present disclosure includes: a device main body; a photoreceptor drum; a developing device; a first toner container; a second toner container; a first vertical transport part; a second vertical transport part; a first horizontal transport part; a second horizontal transport part; a first transport member; a second transport member; a third horizontal transport part; a third transport member; a third vertical transport part; a first transport driving unit; a second transport driving unit; a container driving unit; a first detection sensor; a second detection sensor; a drive control unit; a counting unit; and a consumption amount calculation unit. The photoreceptor drum is rotated about a predetermined axis and has a circumferential surface that allows an electrostatic latent image to be formed and carries a toner image that is in accordance with the electrostatic latent image. The developing device supplies toner to the photoreceptor drum to visualize the electrostatic latent image into the toner image. The first toner container and the second toner container store toner inside and are capable of discharging the toner. The first vertical transport part guides toner discharged from the first toner container downward along a vertical direction. The second vertical transport part guides toner discharged from the second toner container downward along the vertical direction. The first horizontal transport part communicates with a lower end part of the first vertical transport part and guides toner having flowed in from the first vertical transport part in a first direction along a horizontal direction. The second horizontal transport part communicates with a lower end part of the second vertical transport part and guides toner having flowed in from the second vertical transport part in a second direction along the horizontal direction. The first transport member is rotatably arranged in the first horizontal transport part and transports toner in the first direction. The second transport member is rotatably arranged in the second horizontal transport part and transports toner in the second direction. The third horizontal transport part communicates with each of a first direction downstream portion of the first horizontal transport part and a second direction downstream portion of the second horizontal transport part, and receives toner having been transported by the first transport member and toner having been transported by the second transport member at an inside of the third horizontal transport part and guides the toner in a third direction along the horizontal direction. The third transport member is rotatably arranged in the third horizontal transport part and transports toner in the third direction. The third vertical transport part communicates with a third direction downstream portion of the third horizontal transport part and guides toner having been transported by the third transport member to the developing device along the vertical direction. The first transport driving unit generates driving force for selectively rotating the first transport member or the second transport member. The second transport driving unit generates driving force for rotating the third transport member. The container driving unit generates driving force for selectively discharging toner from the first toner container or the second toner container. The first detection sensor is arranged at the first vertical transport part and detects whether or not toner is present in the first vertical transport part. The second detection sensor is arranged at the second vertical transport part and detects whether or not toner is present in the second vertical transport part. The drive control unit controls the first transport driving unit, the second transport driving unit, and the container driving unit. The drive control unit is capable of switching between a first supply state and a second supply state, the first supply state being a state in which, in accordance with a toner supply request from the developing device, toner is supplied to the developing device from the first toner container, the first vertical transport part, the first horizontal transport part, the third horizontal transport part, and the third vertical transport part, the second supply state being a state in which, in accordance with the toner supply request from the developing device, toner is supplied to the developing device from the second toner container, the second vertical transport part, the second horizontal transport part, the third horizontal transport part, and the third vertical transport part, and in the first supply state, the drive control unit, in accordance with information that is detected by the first detection sensor and indicates a toner-less state in the first vertical transport part, controls the container driving unit and causes toner to be discharged from the first toner container to the first vertical transport part, and in accordance with the toner supply request, controls the first transport driving unit and the second transport driving unit to cause the first transport member and the third transport member to rotate in a state in which rotation of the second transport member is stopped, and in the second supply state, the drive control unit, in accordance with information that is detected by the second detection sensor and indicates a toner-less state in the second vertical transport part, controls the container driving unit and causes toner to be discharged from the second toner container to the second vertical transport part, and in accordance with the toner supply request, controls the first transport driving unit and the second transport driving unit to cause the second transport member and the third transport member to rotate in a state in which rotation of the first transport member is stopped. The counting unit accumulates a rotation time of the third transport member. The consumption amount calculation unit calculates a flow rate of toner flowing in the third horizontal transport part in each of the first supply state and the second supply state and thereby calculates a toner consumption amount of each of the first toner container and the second toner container in accordance with the rotation time accumulated by the counting unit.

DETAILED DESCRIPTION

Hereinafter, an image forming device10according to an embodiment of the present disclosure will be described in detail with reference to the drawings. In the present embodiment, description is provided of a tandem-type color printer as one example of an image forming device. The image forming device may be, for example, a copier, a facsimile device, a multifunctional printer incorporating a copier and a facsimile device, or the like. Further, the image forming device may be a printer, a copier, or the like that forms single-color (monochromatic) images.

FIG. 1is a cross-sectional view illustrating the internal structure of the image forming device10. The image forming device10includes a device main body11having a box-shaped housing structure. Inside the device main body11: a sheet feeding unit12that feeds a sheet P; an image forming part13that forms a toner image to be transferred onto the sheet P fed from the sheet feeding unit12; an intermediate transfer unit14at which primary transfer of the toner image takes place; a secondary transfer roller145; and a fixing unit16that performs processing of fixing the unfixed toner image having been formed on the sheet P onto the sheet P are provided. Further, a sheet discharge part171is provided on the upper part of the device main body11. The sheet P having been subjected to the fixing processing in the fixing unit16is discharged from the sheet discharge part171.

Further, at the right side of the image forming part13inside the device main body11, a sheet transport path111that extends in the vertical direction is formed. A transport roller pair that transports the sheet P is provided at an appropriate position along the sheet transport path111. Further, a resist roller pair113that corrects the skew of the sheet P and sends the sheet P to a later-described secondary transfer nip part at a predetermined timing is also provided at the upstream side of this nip part along the sheet transport path111. The sheet transport path111is a transport path that transport the sheet P from the sheet feeding unit12to the sheet discharge part171, via the image forming part13(secondary transfer nip part) and the fixing unit16.

The sheet feeding unit12includes: a sheet feeding tray121; and a pickup roller122. The sheet feeding tray121is attached to a lower position of the device main body11in insertable/removable state, and stores a sheet bundle in which a plurality of the sheets P are stacked. The pickup roller122feeds the uppermost sheet P of the sheet bundle stored in the sheet feeding tray121one by one.

The image forming part13forms a toner image to be transferred onto the sheet P, and includes a plurality of image forming units that form toner images of different colors. In the present embodiment, a yellow unit13Y that uses yellow (Y) toner, a cyan unit13C that uses cyan (C) toner, a magenta unit13M that uses magenta (M) toner, and a black unit13BK that uses black (BK) toner are provided as image forming units. These units are disposed in this order in correspondence with the toner of the plurality of colors from the upstream side to the downstream side (from the left side to the right side inFIG. 1) in the rotation direction of a later-described intermediate transfer belt141. Each unit includes: a photoreceptor drum20and the following devices arranged around the photoreceptor drum20: a charging device21; a developing device23; and a cleaning device25. In addition, a light exposure device22shared by the units is arranged below the image forming units.

The photoreceptor drum20is rotationally driven about a predetermined axis extending in the front-rear direction, and has a circumferential surface that allows an electrostatic latent image to be formed and carries a toner image. The charging device21uniformly charges the surface of the photoreceptor drum20. The light exposure device22has various optical devices such as a light source, a polygon mirror, a reflecting mirror, and a deflecting mirror, and irradiates the circumferential surface of the uniformly charged photoreceptor drum20with light modulated based on image data to form an electrostatic latent image. Further, the cleaning device25cleans the circumferential surface of the photoreceptor drum20after a toner image has been transferred. In the present embodiment, the photoreceptor drum20, the charging device21, and the cleaning device25are integrated with one other to constitute a drum unit2(FIGS. 1 and 2).

The developing device23supplies toner onto the circumferential surface of the photoreceptor drum20in order to develop (visualize) an electrostatic latent image having been formed on the photoreceptor drum20into a toner image. The developing device23accommodates therein magnetic one-component toner as a developer. In the present embodiment, the toner has a characteristic such that the toner is capable of being charged to the positive polarity. In another embodiment, the developing device23may adopt other developing methods, such as a method in which a two-component developer constituted of toner and a carrier is used or a method in which a non-magnetic one component developer is used.

The intermediate transfer unit14is arranged above the image forming part13. The intermediate transfer unit14includes: an intermediate transfer belt141; a driving roller142; a driven roller143; and primary transfer rollers24.

The intermediate transfer belt141is an endless belt-shaped rotating body, and is suspended across the driving roller142and the driven roller143so that the circumferential surface-side of the intermediate transfer belt141contacts the circumferential surface of each photoreceptor drum20. The intermediate transfer belt141is driven to rotate in one direction and carries toner images transferred thereon from the photoreceptor drums20on the surface thereof.

The driving roller142holds the intermediate transfer belt141in tensioned state at the left end-side of the intermediate transfer unit14and drives the intermediate transfer belt141to rotate. The driving roller142is constituted of a metal roller. The driven roller143holds the intermediate transfer belt141in tensioned state at the right end-side of the intermediate transfer unit14. The driven roller143applies tension to the intermediate transfer belt141.

Each primary transfer roller24forms a primary transfer nip part with a photoreceptor drum20with the intermediate transfer belt141therebetween, and performs primary transfer of the toner image on the photoreceptor drum20onto the intermediate transfer belt141. For the photoreceptor drum20of each color, an opposing primary transfer roller24is arranged.

The secondary transfer roller145is arranged to oppose the driving roller142with the intermediate transfer belt141therebetween. The secondary transfer roller145is pressed against the circumferential surface of the intermediate transfer belt141to form the secondary transfer nip part. The toner image having been primarily transferred onto the intermediate transfer belt141undergoes secondary transfer onto the sheet P supplied from the sheet feeding unit12at the secondary transfer nip part. The intermediate transfer unit14and the secondary transfer roller145of the present embodiment constitute a transfer unit of the present disclosure. The transfer unit transfers the toner image having been formed in the image forming part13from the photoreceptor drums20onto the sheet P.

The sheet P supplied to the fixing unit16passes through the fixing nip part and is thereby heated and pressurized. As a result, the toner image having been transferred onto the sheet P at the secondary transfer nip part is fixed onto the sheet P.

The sheet discharge part171is formed by the top part of the device main body11being recessed. The sheet P having been subjected to the fixing processing is discharged onto the sheet discharge part171via the sheet transport path111, which is disposed to extend from the upper part of the fixing unit16.

FIG. 2is a front view of the image forming part13of the image forming device10according to the present embodiment.FIGS. 3 and 4are perspective views of a toner supplying unit5Y and a developing device23Y for the color yellow, in the image forming device10according to the present embodiment.

With reference ofFIGS. 2 to 4, the image forming device10further includes toner supplying units5corresponding to the respective colors. The toner supplying units5supply toner to the developing devices23of the respective colors. In the present embodiment, toner supplying units5(5BK,5M,5C,5Y) of the respective colors are arranged adjacent to one other in the horizontal direction, as illustrated inFIG. 2. Since the toner supplying units5of the respective colors have the same structure and the developing devices23of the respective colors have the same structure, description is provided in the following based on the toner supplying unit5Y and the developing device23Y for the color yellow, as necessary.

The toner supplying units5of the respective colors each have: an upper toner container51(a first toner container); a lower toner container52(a second toner container); an upper housing50A; and a lower housing50B.

The upper toner container51and the lower toner container52each extend along the axial direction of the photoreceptor drums20, and is configured to be capable of storing toner therein and discharging the toner. The upper toner container51and the lower toner container52are mounted onto the device main body11of the image forming device10along a mounting direction DM (the rear direction inFIG. 3). The mounting direction DM is parallel to the axial direction of the photoreceptor drums20. In the present embodiment, the upper toner container51and the lower toner container52are provided with a cylindrical shape, and spiral grooves extending spirally along the axial direction are formed on the outer circumferential surfaces thereof. The spiral grooves form spiral protrusions protruding into the space inside the upper toner container51and space inside the lower toner container52. Further, the upper toner container51and the lower toner container52are rotated by a later-described container driving unit MC, whereby the toner inside is transported toward the rear by the spiral protrusions. The upper toner container51has: a fixed part51A; and a first container gear51G (FIG. 3). The fixed part51A does not rotate, and the portion of the upper toner container51further toward the front than the fixed part51A is configured to be capable of rotating relative to the fixed part51A. The first container gear51G is a gear that is fixed to the outer circumferential part of the upper toner container51at the front of the fixed part51A. Rotational force is transmitted from the container driving unit MC to the first container gear51G, whereby the front portion of the upper toner container51rotates.

Similarly, the lower toner container52has: a fixed part52A; and a second container gear52G (FIG. 3). The fixed part52A does not rotate, and the portion of the lower toner container52further toward the front than the fixed part52A is configured to be capable of rotating relative to the fixed part52A. The second container gear52G is a gear that is fixed to the outer circumferential part of the lower toner container52at the front of the fixed part52A. Rotational force is transmitted from the container driving unit MC to the second container gear52G, whereby the front portion of the lower toner container52rotates.

Note that the upper toner container51has a toner discharge port510(seeFIG. 7) formed in the front end-side thereof (the fixed part51A) in the mounting direction DM, which is the direction in which the upper toner container51is mounted onto the upper housing50A, and the lower toner container52has an undepicted toner discharge port formed in the front end-side thereof (the fixed part52A) in the mounting direction DM, which is the direction in which the lower toner container52is mounted onto the lower housing50B. Toner is discharged from these toner discharge ports. Further, the upper toner container51and the lower toner container52are provided with shutters51S and52S (FIGS. 3 and 4) for sealing the toner discharge ports. When the upper toner container51and the lower toner container52are mounted onto the upper housing50A and the lower housing50B, these shutters are slidingly moved to open the respective toner discharge ports, as will be described later. Further, in the present embodiment, the upper toner container51and the lower toner container52are toner containers of the same shape. In other words, the toner container of each color applied to the image forming device10can be mounted onto either one of the upper housing50A and the lower housing50B in the toner supplying unit5of the corresponding color. Note that the upper toner container51and the lower toner container52of each color are arranged in a container space S of the device main body11illustratedFIG. 1.

In the device main body11, the upper housing50A is arranged above the developing device23with a space therebetween. The upper housing50A allows the upper toner container51to be mounted inside the upper housing50A along the mounting direction DM and accommodates the upper toner container51. In the device main body11, the lower housing50B is arranged above the developing device23and below the upper housing50A. The lower housing50B allows the lower toner container52to be mounted inside the lower housings50B along the mounting direction DM and accommodates the lower toner container52.

With reference toFIG. 3, note that in the present embodiment, the lower housing50B positions the lower toner container52inside the device main body11so that the mounting direction front end part of the lower toner container52(i.e., the rear end part of the lower toner container52) is arranged at the same position in the mounting direction as the mounting direction front end part of the upper toner container51mounted onto the upper housing50A (i.e., the rear end part of the upper toner container51). Further, in the device main body11, the lower housing50B is arranged at a position that is above the developing device23, is below the upper housing50A, and is shifted toward the left with respect to the upper housing50A in a direction (the left-right direction) that is horizontal and is perpendicular to the axial direction of the photoreceptor drums20(FIG. 2toFIG. 4). As a result, a later-described first vertical transport part56can be arranged in a space that is below the mounting direction front end part of the upper toner container51(i.e., the rear end part of the upper toner container51) and faces the mounting direction front end part of the lower toner container52in the direction that is horizontal and is perpendicular to the axial direction of the photoreceptor drums20, without interfering with the lower toner container52.

FIG. 5is a perspective view of a first transport driving unit101, a second transport driving unit102, a first transport screw74, a second transport screw75, and a third transport screw85according to the present embodiment, andFIG. 6is a lateral view of the same.

The toner supplying unit5further includes: a first vertical transport part56; a second vertical transport part57; a first horizontal transport part58; a second horizontal transport part59; a merging part500(a horizontal merging part60and a third vertical transport part65); the first transport screw74(a first transport member); the second transport screw75(a second transport member); the third transport screw85(a third transport member); a screw driving unit70; the container driving unit MC (FIG. 8); a first sensor S1(a first detection sensor); a second sensor S2(a second detection sensor); and a control unit90(FIG. 8).

The first vertical transport part56is a pipe-shaped member provided to the device main body11so as to extend downward from near the first container shutter51S. The first vertical transport part56guides toner discharged from the upper toner container51downward along the vertical direction. Therefore, when the upper toner container51is mounted onto the upper housing50A, the first vertical transport part56and the fixed part51A of the upper toner container51communicate with one another.

The second vertical transport part57is a pipe-shaped member provided to the device main body11so as to extend downward from near the second container shutter52S. The second vertical transport part57guides toner discharged from the lower toner container52downward along the vertical direction. Therefore, when the lower toner container52is mounted onto the lower housing50B, the second vertical transport part57and the fixed part52A of the lower toner container52communicate with one another.

The first horizontal transport part58is a pipe-shaped member extending in the horizontal direction. The first horizontal transport part58receives toner from the first vertical transport part56and transfers the toner to the merging part500(the horizontal merging part60) while transporting the toner toward the rear left (a first direction) along the horizontal direction. In other words, the first horizontal transport part58communicates with the lower end part of the first vertical transport part56, and guides the toner flowing in from the first vertical transport part56in the first direction along the horizontal direction.

The second horizontal transport part59is a pipe-shaped member extending in the horizontal direction. The second horizontal transport part59receives toner from the second vertical transport part57and transfers the toner to the merging part500(the horizontal merging part60) while transporting the toner toward the front right (a second direction) along the horizontal direction. In other words, the second horizontal transport part59communicates with the lower end part of the second vertical transport part57, and guides the toner flowing in from the second vertical transport part57along the second direction.

The first transport screw74(FIG. 5) is rotatably arranged in the first horizontal transport part58and transports toner in the first direction (arrow D1inFIG. 5). The first transport screw74has: a first shaft741; a first main transport blade742; and a first paddle743.

The first shaft741serves as the rotation axis of the rotation of the first transport screw74. The first main transport blade742is a spiral blade arranged on the first shaft741. The first paddle743is a paddle arranged on the first shaft741and sends toner into the horizontal merging part60(arrow DL1inFIG. 5). The first main transport blade742transports toner from the position (see arrow T1inFIG. 5) at which toner flows into the first horizontal transport part58from the first vertical transport part56toward the first paddle743at the rear.

The second transport screw75(FIG. 5) is rotatably arranged in the second horizontal transport part59and transports toner in the second direction (arrow D2inFIG. 5). The second transport screw75has: a second shaft751; a second main transport blade752; and a second paddle753.

The second shaft751serves as the rotation axis of the rotation of the second transport screw75. The second main transport blade752is a spiral blade arranged on the second shaft751. The second paddle753is a paddle arranged on the second shaft751and sends toner into the horizontal merging part60(arrow DL1inFIG. 5). The second main transport blade752transports toner from the position (see arrow T2inFIG. 5) at which toner flows into the second horizontal transport part59from the second vertical transport part57toward the second paddle753at the front.

The merging part500communicates with each of the first horizontal transport part58and the second horizontal transport part59. The merging part500receives therein the toner transported by the first transport screw74and the toner transported by the second transport screw75, and transports the toner toward the developing device23(23Y inFIG. 3). The merging part500has: the horizontal merging part60(a third horizontal transport part); and a third vertical transport part65.

The horizontal merging part60has a pipe shape arranged to extend in parallel with the first horizontal transport part58and the second horizontal transport part59below the first horizontal transport part58and the second horizontal transport part59. The horizontal merging part60communicates, through a same undepicted opening, with each of a first direction downstream portion (below the first paddle743) of the first horizontal transport part58and a second direction downstream portion (below the second paddle753) of the second horizontal transport part59, and receives therein the toner transported by the first transport screw74and the toner transported by the second transport screw75. Further, the horizontal merging part60guides the toner so received toward the front right (a third direction; arrow D3inFIG. 5) along the horizontal direction. The horizontal merging part60has the third transport screw85(the third transport member), which is rotatably arranged inside the pipe shape (FIG. 5). The third transport screw85has the function of transporting toner in the third direction inside the horizontal merging part60. The third transport screw85has: a third shaft850; a third main transport blade851; and a third paddle852.

The third shaft850(FIG. 5) serves as the rotation axis of the rotation of the third transport screw85. The third main transport blade851is a spiral blade arranged on the third shaft850. The third main transport blade851causes the toner received from the first horizontal transport part58(the first transport screw74) and the second horizontal transport part59(the second transport screw75) to flow into the third vertical transport part65while transporting the toner toward the front right (the third direction) along the horizontal direction. The third paddle852is a paddle arranged on the third shaft850at the downstream side of the third main transport blade851. The third paddle852helps the toner that is transported by the third main transport blade851as the third transport screw85rotates to flow into the third vertical transport part65(arrow DL2inFIG. 5).

The third vertical transport part65has a pipe shape arranged to extend downward along the vertical direction from the third direction downstream portion of the horizontal merging part60. The upper end part of the third vertical transport part65communicates with the horizontal merging part60and the lower end part of the third vertical transport part65communicates with the developing device23Y. That is, the third vertical transport part65guides the toner transported by the third transport screw85to the developing device23along the vertical direction.

The screw driving unit70(FIG. 3) generates driving force for causing the first transport screw74, the second transport screw75, and the third transport screw85to rotate. The screw driving unit70includes: the first transport driving unit101; the second transport driving unit102; and a PI sensor91. The first transport driving unit101includes: a first motor M1; a first worm wheel71(a first intermediate gear); a first one-way gear72(a one-way clutch; a first transmission member); and a second one-way gear73(a one-way clutch; a second transmission member). The second transport driving unit102includes: a second motor M2; and a second worm wheel81(a second intermediate gear).

The first motor M1is a motor that is configured to be rotatable in a first rotation direction and a second rotation direction opposite the first rotation direction. The rotation, the stopping, and the rotation direction of the first motor M1are controlled by a drive control unit901of the later-described control unit90. As a result, the first motor M1generates driving force for selectively driving the first transport screw74or the second transport screw75to rotate.

The first worm wheel71is connected to an output shaft M11(FIG. 6) of the first motor M1. The first worm wheel71is configured so that the first worm wheel71can also rotate in different rotation directions depending upon the rotation direction of the first motor M1. The first worm wheel71is rotatably supported by an end part of the third shaft850of the third transport screw85. Note that the first worm wheel71and the third transport screw85rotate independently of one another other. The first worm wheel71is arranged coaxially with the third transport screw85at one end side of the third transport screw85, and receives the end of the third transport screw85therein (allows one end of the third transport screw85to be inserted therethrough). Further, the first worm wheel71is rotatable relative to the third transport screw85. The first worm wheel71transmits rotational driving force of the first motor M1to the first one-way gear72and the second one-way gear73. According to such a configuration, the space occupied by the first transport driving unit101and the second transport driving unit102can be made compact, as illustrated inFIG. 5.

The first one-way gear72is a gear engaged with the first worm wheel71, and is fixed to one end of the first shaft741of the first transport screw74. When rotational driving force is transmitted from the first worm wheel71to the first one-way gear72, the first transport screw74rotates and toner is transported. The first one-way gear72is interposed between the first motor M1and the first transport screw74. The first one-way gear72allows the first transport screw74to rotate when the first motor M1is rotated in the first rotation direction, whereas the first one-way gear72inhibits the first transport screw74from rotating when the first motor M1is rotated in the second rotation direction.

Similarly, the second one-way gear73is a gear engaged with the first worm wheel71at a position differing from the position at which the first one-way gear72is engaged with the first worm wheel71, and is fixed to one end of the second shaft751of the second transport screw75. When rotational driving force is transmitted from the first worm wheel71to the second one-way gear73, the second transport screw75rotates and toner is transported. The second one-way gear73is interposed between the first motor M1and the second transport screw75. The second one-way gear73allows the second transport screw75to rotate when the first motor M1is rotated in the second rotation direction, whereas the second one-way gear73inhibits the second transport screw75from rotating when the first motor M1is rotated in the first rotation direction.

The second motor M2is a motor that is configured to be rotatable in a predetermined rotation direction. The second motor M2generates driving force for rotating the third transport screw85. The rotation, the stopping, and the rotation direction of the second motor M2are controlled by the drive control unit901of the later-described control unit90. The second motor M2is provided with an output shaft M21.

The second worm wheel81is a gear engaged with the output shaft M21(FIG. 6) of the second motor M2, and is fixed to an end part of the third shaft850of the third transport screw85. Therefore, the second worm wheel81and the third transport screw85rotate integrally. That is, the second worm wheel81has the function of transmitting rotational driving force of the second motor M2to the third transport screw85. The second worm wheel81is provided with a detection-target piece81H. The detection-target piece81H is fixed to one end of the second worm wheel81in the axial direction, and has a pair of slits formed therein in the circumferential direction, as illustrated inFIG. 5. The rotation of the detection-target piece81H is detected by the PI sensor91, whereby the rotation count (cumulative rotation count) of the third transport screw85is detected.

As described above, the PI sensor91is arranged in the device main body11of the image forming device10so as to face the detection-target piece81H of the second worm wheel81. The PI sensor91includes: an undepicted emission unit for emitting detection light; and a light reception unit for receiving the detection light. The detection-target piece81H blocks the detection light while the slit portions of the detection-target piece81H allow the detection light to pass through, whereby the rotation of the second worm wheel71, or that is, the rotation of the third transport screw85is detected.

The container driving unit MC (FIG. 8) generates driving force for selectively discharging toner from the upper toner container51or the lower toner container52. In the present embodiment, the container driving unit MC includes an undepicted motor connected to each of the first container gear51G and the second container gear52G. The motor may be arranged one for each of the first container gear51G and the second container gear52G. Alternatively, the motor may be such that the first container gear51G or the second container gear52G is selectively rotated depending upon the rotation direction of one motor, similarly to the above-described screw driving unit70. Note that the toner discharge amount from the upper toner container51and the lower toner container52is desirably set to be greater than the toner supply amount required at the developing device23.

The first sensor S1(FIGS. 3 and 8) is arranged to face the lower end part of the first vertical transport part56, and detects whether or not toner is present inside the pipe of the first vertical transport part56. Similarly, the second sensor S2(FIG. 8) is arranged to face the lower end part of the second vertical transport part57, and detects whether or not toner is present inside the pipe of the second vertical transport part57. These sensors are constituted of magnetic permeability sensors. When a sufficient amount of toner is present inside the first vertical transport part56or the second vertical transport part57, the corresponding sensor outputs a HIGH signal (+5V). Meanwhile, when hardly any toner is present inside the first vertical transport part56or the second vertical transport part57, the corresponding sensor outputs a LOW signal (0V). In other embodiments, these sensors may be PI sensors (photosensors). In such a case, the first vertical transport part56and the second vertical transport part57are constituted of transparent pipe members, and whether or not colored toner is present inside the first vertical transport part56and the second vertical transport part57is detected by the PI sensors. Further, the first sensor S1and the second sensor S2may be other optical sensors (transmission sensors, reflection sensors), piezoelectric sensors, etc.

With reference toFIGS. 2 and 3, the upper toner container51, which has a cylindrical shape extending along a predetermined longitudinal direction, is configured to be attachable and detachable to and from a first position inside the device main body11, and the lower toner container52, which has the same shape as the upper toner container51, is configured to be attachable and detachable to and from a second position that is below the first position inside the device main body11. Further, the lower toner container52having been mounted onto the second position is arranged at a position shifted toward the left from the upper toner container51having been mounted onto the first position. Here, the upper toner container51and the lower toner container52are respectively mounted onto the first position and the second position along the mounting direction DM, which is parallel to the longitudinal direction. Meanwhile, the vertical direction length of the first vertical transport part56is set longer than the vertical direction length of the second vertical transport part57.

FIG. 7is a schematic cross-sectional view illustrating a state in which the upper toner container51is being attached to the device main body11of the image forming device10according to the present embodiment. Note that the lower toner container52and the second vertical transport part57also have structures similar to the structures illustrated inFIG. 7. In addition to the above-described first container shutter51S, the upper toner container51has: the toner discharge port510; a spring512; a spring fixing part513; and a shutter pressing part514. The toner discharge port510is opened at the front end part of the upper toner container51, and allows toner to be discharged. The first container shutter51S is held by the main body portion of the upper toner container51to be slidingly-movable along the front-rear direction. The first container shutter51S opens and seals the toner discharge port510. The first container shutter51S has an L shape in lateral view. The spring512biases the first container shutter51S in the direction in which the first container shutter51S seals the toner discharge port510. The base end part of the spring512is fixed to the spring fixing part513, which is disposed to protrude from the main body portion of the upper toner container51. The shutter pressing part514is a protrusion protruding toward the rear from the front end part of the upper toner container51.

Meanwhile, the first vertical transport part56has: a toner inflow port560; a main body-side shutter561; a spring562; and a spring fixing part563. The toner inflow port560is an opening opened at the upper end part of the first vertical transport part56, and receives toner from the toner discharge port510. The main body-side shutter561is supported by the upper end part of the first vertical transport part56to be slidingly-movable in the front-rear direction. The main body-side shutter561opens and seals the toner inflow port560. The main body-side shutter561has an L shape in lateral view. The spring562biases the main body-side shutter561in the direction in which the main body-side shutter561seals the toner inflow port560. The base end part of the spring562is fixed to the spring fixing part563. A shutter pressing part564is a protrusion disposed to protrude toward the front from the upper end part of the first vertical transport part56at the opposite side from the spring562.

When the upper toner container51is mounted onto the first position (FIGS. 2 and 3) of the device main body11along the direction of the arrow DM inFIG. 7, the shutter pressing part514of the upper toner container51pushes the main body-side shutter561toward the rear (arrow D71), whereby the toner inflow port560opens while the spring562is compressed. Meanwhile, when the upper toner container51is mounted, the shutter pressing part564of the first vertical transport part56pushes the first container shutter51S toward the rear (arrow D72). As a result, the toner discharge port510opens while the spring512is compressed. That is, the toner discharge port510and the toner inflow port560are put in communication with one another.

Hence, in the present embodiment, a configuration is made so that, when the upper toner container51is mounted onto the first position inside the device main body11, at least a part of the toner in the upper toner container51is capable of flowing into the first vertical transport part56by free fall (arrow D73). Similarly, a configuration is made so that, when the lower toner container52is mounted onto the second position inside the device main body11, at least a part of the toner in the lower toner container52is capable of flowing into the second vertical transport part57by free fall. Accordingly, when a new upper toner container51is mounted after the first vertical transport part56becomes empty of toner therein, the first sensor S1detects the toner that has freely fallen and the control unit90is thereby capable of detecting that the upper toner container51has been replaced. The same applies to the lower toner container52.

FIG. 8is a block diagram of the control unit90of the image forming device10according to the present embodiment. The control unit90is constituted of: a central processing unit (CPU); a read only memory (ROM) that stores a control program; a random access memory (RAM) that is used as the CPU working area; etc. In addition to the first sensor S1, the second sensor S2, the PI sensor91, the container driving unit MC, the first motor M1, and the second motor M2, which have been described above, a display unit92, a toner sensor93, etc., are electrically connected to the control unit90. Further, the control unit90is connected to a network in order to transmit operation information and failure information of the image forming device10to an information management center located at a remote location.

The toner sensor93(FIGS. 3 and 8) is provided to each developing device23(23Y), and outputs a detection signal that is in accordance with the amount of toner inside the developing device23. When the amount of toner inside the developing device23is equal to or more than a predetermined threshold value, the toner sensor93outputs a HIGH signal (+5V). Meanwhile, when the amount of toner inside the developing device23is less than the predetermined threshold value, the toner sensor93outputs a LOW signal (0V). The toner sensor93may be configured so that the more the amount of toner inside the developing device23, the greater the detection signal (voltage) that is output. The detection signal output by the toner sensor93is referred to by the drive control unit901of the control unit90as a toner supply request from the developing device23.

The display unit92is provided to an undepicted operation unit of the image forming device10. The display unit92displays information for operating the image forming device10, the operation state of the image forming device10, etc.

By the CPU executing the control program stored in the ROM, the control unit90functions to include: the drive control unit901; a counting unit902; a consumption amount calculation unit903; and a storage unit904.

The drive control unit901controls the drive of the first motor M1, the second motor M2, and the container driving unit MC. The drive control unit901performs switching between a first supply state and a second supply state. In the first supply state, in accordance with the toner supply request from the developing device23(23Y), toner is supplied to the developing device23from the upper toner container51, the first vertical transport part56, the first horizontal transport part58, the horizontal merging part60, and the third vertical transport part65. In the second supply state, in accordance with the toner supply request from the developing device23(23Y), toner is supplied to the developing device23from the lower toner container52, the second vertical transport part57, the second horizontal transport part59, the horizontal merging part60, and the third vertical transport part65.

In the first supply state, the drive control unit901, in accordance with a LOW signal (information indicating toner-less state in the first vertical transport part56) detected by the first sensor S1, controls the container driving unit MC and thereby causes toner to be discharged from the upper toner container51to the first vertical transport part56, and also, the drive control unit901, in accordance with the toner supply request, controls the first motor M1to drive in the first rotation direction and causes the first transport screw74to rotate in a state in which the rotation of the second transport screw75is stopped, and also controls the second motor M2to drive and thereby causes the third transport screw85to rotate.

Meanwhile, in the second supply state, the drive control unit901, in accordance with a LOW signal (information indicating toner-less state in the second vertical transport part57) detected by the second sensor S2, controls the container driving unit MC and thereby causes toner to be discharged from the lower toner container52to the second vertical transport part57, and also, the drive control unit901, in accordance with the toner supply request, controls the first motor M1to drive in the second rotation direction and causes the second transport screw75to rotate in a state in which the rotation of the first transport screw74is stopped, and also controls the second motor M2to drive and thereby causes the third transport screw85to rotate.

The counting unit902separately accumulates the rotation time of the third transport screw85in the first supply state and the rotation time of the third transport screw85in the second supply state. In doing so, the counting unit902detects the rotation time of the third transport screw85by referring to the output signal from the PI sensor91, which is in accordance with the rotation of the detection-target piece81H of the second worm wheel81.

The consumption amount calculation unit903, in accordance with the rotation times accumulated by the counting unit902, calculates the flow rate of toner flowing in the horizontal merging part60in each of the first supply state and the second supply state, and thereby calculates the toner consumption amount of each of the upper toner container51and the lower toner container52. The toner flow rate in the horizontal merging part60can be calculated as the product of the cross-sectional area of the pipe shape of the horizontal merging part60, the rotation count (the rotation speed) of the third transport screw85, and the spiral blade pitch of the third main transport blade851. Here, the first horizontal transport part58and the second horizontal transport part59are kept in toner-filled state, because toner is supplied as necessary from the upper toner container51to the first vertical transport part56in accordance with detection signals from the first sensor S1, and toner is supplied as necessary from the lower toner container52to the second vertical transport part57in accordance with detection signals from the second sensor S2. Accordingly, the horizontal merging part60, which receives toner from the first horizontal transport part58and the second horizontal transport part59, is also kept in toner-filled state, and thus, toner flow rate can be accurately calculated by calculating the above-described product. Further, the toner flow rate in the horizontal merging part60having been calculated and the cumulative rotation times counted by the counting unit902are multiplied, whereby the toner consumption amount of each of the upper toner container51and the lower toner container52can be calculated.

Note that the counting unit902resets the respective cumulative rotation times when a new upper toner container51and a new lower toner container52are mounted onto the image forming device10. For the acquisition of information regarding the mounting of the new upper toner container51and the new lower toner container52, information from an undepicted RFID memory provided to each container may be referred to besides the output from the first sensor S1and the second sensor S2. Further, information regarding the mounting of the new upper toner container51and the new lower toner container52may be input from the undepicted operation unit of the image forming device10by a user or a maintenance worker. Further, when the consumption amount of each toner container approaches the amount of toner filling new toner containers, the consumption amount calculation unit903causes the display unit92to display empty information of the toner container. As a result, a user can recognize that a toner container is approaching empty state or has reached the empty state. Note that when one of the upper toner container51and the lower toner container52becomes empty, the drive control unit901switches the drive of the container driving unit MC, the first motor M1, and the second motor M2between the first supply state and the second supply state so that toner is supplied to the developing device23from the other toner container.

The storage unit904has stored therein in advance information of various threshold values and calculation information such as constants to be used for calculation, which are to be referred to by the drive control unit901and the consumption amount calculation unit903.

As described above, in the present embodiment, in the device main body11, two toner containers are arranged with respect to the developing device23. Further, toner can be selectively supplied from the two toner containers to the developing device23, and thus the amount of time can be shortened during which the operation of the image forming device10stops as a result of a toner container becoming empty of toner. The upper toner container51and the lower toner container52are arranged inside the device main body11so that the upper toner container51and the lower toner container52are adjacent to one another in the vertical direction and the horizontal direction (in an oblique arrangement). Therefore, an increase in the horizontal direction width of the device main body11can be suppressed compared to a case in which two toner containers are arranged to be adjacent to one another only in the horizontal direction. Further, the drive control unit901of the control unit90controls the driving system (the container driving unit MC, the first motor M1, and the second motor M2) of the toner supplying unit5so that toner is supplied to the developing device23from one toner container among the upper toner container51and the lower toner container52and so that, when this toner container becomes empty, toner is supplied to the developing device23from the other toner container among the upper toner container51and the lower toner container52. Hence, a configuration is made so that, even when the upper toner container51becomes empty, an image forming operation can be promptly executed by using the lower toner container52. As a result, the frequency and time are reduced of stops of the image forming operation occurring due to a situation in which a toner container becomes empty of toner and the toner container is replaced.

Further, in the present embodiment, the first transport screw74of the first horizontal transport part58and the second transport screw75of the second horizontal transport part59, which transport toner to the horizontal merging part60, are selectively driven to rotate. Hence, a situation in which toner from the upper toner container51and toner from the lower toner container52are mixed inside the horizontal merging part60is suppressed compared to a case in which both the first transport screw74and the second transport screw75are simultaneously rotated. Thus, the toner consumption amount of the upper toner container51and the toner consumption amount of the lower toner container52can each be calculated based on the toner flow rate in the horizontal merging part60. In particular, it is possible to calculate the consumption amounts of the two toner containers independently and accurately. Further, the container driving unit MC is controlled in accordance with detection information from the first sensor S1and the second sensor S2so that the first vertical transport part56and the second vertical transport part57, which are respectively located at the upstream side of the first horizontal transport part58and the second horizontal transport part59, are filled with toner. Thus, the toner consumption amount of the upper toner container51and the toner consumption amount of the lower toner container52can each be calculated accurately based on the toner flow rate in the horizontal merging part60, because the horizontal merging part60is filled with toner.

Further, in the present embodiment, the upper toner container51and the lower toner container52are arranged at the same mounting direction position inside the device main body11. Therefore, the size of the device main body11in the front-rear direction can be reduced compared to a case in which the upper toner container51and the lower toner container52are arranged to be displaced from one another in the front-rear direction. Further, the first vertical transport part56is arranged below the mounting direction front end part of the upper toner container51mounted onto the first position so that, in the horizontal direction, the first vertical transport part56faces the mounting direction front end part of the lower toner container52mounted onto the second position (FIG. 3). Therefore, a part of the toner supplying unit5(the first vertical transport part56) can be efficiently arranged by utilizing a step portion formed by the two toner containers. Therefore, the vertical direction size and the horizontal direction size of the image forming device10can be made compact.

Further, in the present embodiment, the transmission destination of rotational driving force of the first motor M1is switched between the first transport screw74and the second transport screw75depending upon the rotation direction of the first motor M1. Therefore, it becomes possible to selectively rotate the first transport screw74or the second transport screw75by using the rotational driving force of one first motor M1. Hence, it is possible to selectively transport toner in the first horizontal transport part58or the second horizontal transport part59, and thus, the toner supply system of the image forming device10can be realized with a compact size and at a low cost.

Further, in the present embodiment, the position at which the first horizontal transport part58and the horizontal merging part60communicate with one another is arranged at a predetermined distance along the horizontal direction with respect to the position at which the first vertical transport part56and the first horizontal transport part58communicate with one another (a step shape is formed). Further, the position at which the second horizontal transport part59and the horizontal merging part60communicate with one another is arranged at a predetermined distance along the horizontal direction with respect to the position at which the second vertical transport part57and the second horizontal transport part59communicate with one another (a step shape is formed). Since such step shapes are provided, a situation in which toner inside the first vertical transport part56flows into the horizontal merging part60while the rotation of the first transport screw74is being stopped can be prevented. Similarly, a situation in which toner inside the second vertical transport part57flows into the horizontal merging part60while the rotation of the second transport screw75is being stopped can be prevented.

In the present embodiment, when the upper toner container51is mounted onto the device main body11, a part of the toner inside the upper toner container51flows into the first vertical transport part56by free fall, as illustrated inFIG. 7. Similarly, when the lower toner container52is mounted onto the device main body11, a part of the toner inside the lower toner container52flows into the second vertical transport part57by free fall. Further, the vertical direction length of the first vertical transport part56is set longer than the vertical direction length of the second vertical transport part57. According to such a configuration, the amount of toner flowing into the first vertical transport part56when a new upper toner container51is mounted onto the first position tends to be greater than the amount of toner flowing into the second vertical transport part57when a new lower toner container52is mounted onto the second position. In such a case, it becomes difficult to accurately calculate the consumption amounts of the toner containers if toner rapidly flows into the horizontal merging part60from the first vertical transport part56and the second vertical transport part57through the first horizontal transport part58and the second horizontal transport part59, respectively. Even in such a case, a situation in which toner inside the first vertical transport part56flows into the horizontal merging part60while the rotation of the first transport screw74is being stopped can be prevented, because the toner supply system of the image forming device10is provided with the structure as illustrated inFIG. 5according to this configuration. Similarly, a situation in which toner inside the second vertical transport part57flows into the horizontal merging part60while the rotation of the second transport screw75is being stopped can be prevented. Therefore, it is possible to accurately calculate the consumption amount of each toner container.

Further, in the present embodiment, the image forming part13includes a plurality of image forming units13BK,13M,13C,13Y arranged in correspondence with toners of a plurality of colors, and the upper toner containers51of the plurality of image forming units are arranged adjacent to one another in the horizontal direction and the lower toner containers52of the plurality of image forming units are arranged adjacent to one another in the horizontal direction. Further, when viewed along the axial direction of the photoreceptor drums20, the upper toner containers51and the lower toner containers52of the plurality of image forming units are arranged in a staggered pattern. Therefore, even when a configuration is adopted in which an image is formed on a sheet P by using toner of a plurality of colors, the frequency of occurrence of a situation in which the image forming operation stops due to the replacement of toner containers of the respective colors can be reduced and an increase in size of the device main body11in the horizontal direction can be suppressed. Further, as illustrated inFIG. 2, the intermediate transfer unit14is arranged by utilizing the height across which toner is supplied from the upper toner containers51and the lower toner containers52to the developing devices23of the respective colors. In other words, the toner supplying units5of the respective colors are arranged by using positions above and behind the intermediate transfer unit14.

Further, in the present embodiment, the upper toner container51and the lower toner container52are mounted onto the device main body11along the predetermined horizontal mounting direction DM (the rear direction), and the first direction and the second direction are inclined by a predetermined angle with respect to the mounting direction (FIG. 4). Therefore, the space occupied by the first horizontal transport part58and the second horizontal transport part59can be made compact.

The image forming device10according to one embodiment of the present disclosure has been described in detail above. According to such a configuration, it is possible to provide an image forming device that includes a toner supply system in which toner discharged from a plurality of toner containers is supplied to a developing device after merging and that is capable of accurately calculating the toner consumption amount of each toner container. Note that the present disclosure is not limited to this. For example, the present disclosure can adopt modified embodiments as described in the following.

(1) In the above embodiment, description has been provided based on a form in which a toner supplying unit5and a developing device23are arranged for toner of each of the four colors. However, the present disclosure may also be applied to an image forming device (a monochromatic device or the like) that includes a structure as illustrated inFIG. 3.

(2) In the above-described embodiment, description is provided based on a form in which the upper toner container51and the lower toner container52transport toner inside by the main body portions of the containers rotating. However, the toner containers may be those in which rotatable toner transport members, such as screws, are provided inside the toner containers.

(3) Further, the toner supply request from the developing device23that the drive control unit901refers to for executing toner discharge from the upper toner container51and the lower toner container52is not limited to the output from the toner sensor93. A form may be adopted in which the judgment of toner supply with respect to the developing device23is made based on other types of information, such as image information in the image forming device10, density information of patch images on the intermediate transfer belt141of the intermediate transfer unit14, etc.

(4) In the structure of the image forming device10illustrated inFIG. 2, an individual openable/closable cover may be provided in front of each of the eight toner containers (the upper toner containers51and the lower toner containers52). The toner containers can be replaced by opening these covers. Further, it is desirable that the opening/closing of each cover is locked/unlocked by an undepicted lock mechanism. In such a case, the control unit90releases the lock mechanism of the cover facing a toner container that has become empty, whereby erroneous replacement of toner containers in which toner is present can be prevented.