Patent ID: 12204261

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, an image forming apparatus according to one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the disclosed embodiments. In the following description, the same parts are assigned with the same reference signs. Their names and functions are also the same. Therefore, detailed description thereof is not repeated.

FIG.1is a view illustrating an example of a schematic internal configuration of an image forming apparatus in an embodiment of the present invention. InFIG.1, members required for describing the present invention are illustrated, and the image forming apparatus of the present invention is not limited to the example illustrated inFIG.1. With reference toFIG.1, An image forming apparatus1includes a main body11, a paper feeding device13, and a winding device15. The paper feeding device13is arranged at a preceding stage of the main body11, and the winding device15is arranged at a subsequent stage of the main body11. The paper feeding device13feeds roll paper R to the main body11in a conveyance direction indicated by an arrow inFIG.1. The winding device15winds the roll paper R on which an image is formed by the main body11. The roll paper R wound by the winding device15is processed by a post-processer (not illustrated). The post-processor cuts out, for example, a label image, a package image and the like formed on the roll paper R.

The main body11includes an image former IM and a controller90. The controller90controls the image former IM. The controller90includes a central processing unit (CPU) and a memory and controls the image former IM by executing a program stored in the memory. The image former IM includes image forming units20Y,20M,20C,20K, and20W corresponding to yellow, magenta, cyan, black, and white, respectively. Herein, “Y”, “M”, “C”, “K”, and “W” represent yellow, magenta, cyan, black, and white, respectively. When at least one of the image forming units20Y,20M,20C,20K, and20W is driven, an image is formed. When all of the image forming units20Y,20M,20C,20K, and20W are driven, a full-color image is formed. Printing data of yellow, magenta, cyan, black, and white are input to the image forming units20Y,20M,20C,20K, and20W, respectively. The image forming units20Y,20M,20C,20K, and20W are the same except for different colors of toner to be handled, so that the image forming unit20Y for forming a yellow image is herein described.

The image forming unit20Y includes a developing device21Y, a photosensitive drum22Y as an image carrier, a bottle storage40Y to which a toner bottle30Y is detachably attached, a first toner storage50Y, and a second toner storage60Y. The developing device21Y includes a developing roller25Y; the developing roller25Y includes a built-in magnet roller and holds charged toner stored in the developing device21Y by an action of a magnetic force. The photosensitive drum22Y has a cylindrical shape, and a charging roller23Y, an exposure device24Y, the developing roller25Y, and a primary transfer roller26Y are sequentially arranged around the photosensitive drum22Y in a rotation direction of the photosensitive drum22Y.

The photosensitive drum22Y is irradiated with laser light emitted by the exposure device24Y after a surface thereof is charged by the charging roller23Y. The exposure device24Y exposes an image corresponding portion on the surface of the photosensitive drum22Y to form an electrostatic latent image. As a result, the electrostatic latent image is formed on the photosensitive drum22Y Subsequently, the developing device21Y develops the electrostatic latent image formed on the photosensitive drum22Y with toner. Specifically, the toner held by the developing roller25Y is placed on the electrostatic latent image formed on the photosensitive drum22Y by an action of an electric field force, so that a toner image is formed on the photosensitive drum22Y The toner image formed on the photosensitive drum22Y is transferred onto an intermediate transfer belt29as an image carrier by an action of an electric field force by the primary transfer roller26Y.

The intermediate transfer belt29is suspended by a driving roller R1and a driven roller R2so as not to slack. When the driving roller R1rotates clockwise inFIG.1, the intermediate transfer belt29rotates clockwise in the drawing at a predetermined speed. As the intermediate transfer belt29rotates, the driven roller R2rotates clockwise.

As a result, the image forming units20Y,20M,20C,20K, and20W transfer the toner images onto the intermediate transfer belt29in this order. A timing at which each of the image forming units20Y,20M,20C,20K, and20W transfers the toner image onto the intermediate transfer belt29is adjusted by detection of a reference mark attached to the intermediate transfer belt29. As a result, yellow, magenta, cyan, black, and white toner images are superimposed on the intermediate transfer belt29.

The toner image formed on the intermediate transfer belt29is transferred onto the roll paper R by an action of an electric field force by a secondary transfer roller R3. The roll paper R onto which the toner image is transferred is conveyed to a fixing roller pair R4to be heated and pressurized. As a result, the toner is melted to be fixed to the roll paper R.

The image forming apparatus1drives all of the image forming units20Y,20M,20C, and20K in a case of forming a full-color image, but drives any one of the image forming units20Y,20M,20C,20K, and20W in a case of forming a monochrome image. It is also possible to form an image by combining two or more of the image forming units20Y,20M,20C,20K, and20W.

A terminal device such as a personal computer operated by a user is connected to the controller90via a network not illustrated. The controller90executes a job input from the terminal device and controls the image forming units20Y,20M,20C,20K, and20W to form an image on the roll paper R. The job includes image data indicating images to be formed by the image forming units20Y,20M,20C,20K, and20W, and includes image forming conditions for forming the image of the image data. The image forming conditions include a position where the image of the image data is arranged on the roll paper R, the number of images of the image data to be formed on the roll paper R and the like. In a case where the controller90executes the job, the controller90controls the image forming units20Y,20M,20C,20K, and20W such that the image of the image data is formed under the image forming conditions defined by the job.

FIG.2is a plan view illustrating an internal configuration of the image forming unit.FIG.3is a cross-sectional view taken along line A-A inFIG.2.FIG.4is a view illustrating a part of a cross section taken along line B-B inFIG.2.FIG.5is a view illustrating a part of a cross section taken along line C-C inFIG.3. InFIGS.2to5, some members are omitted to illustrate the internal configuration of the image forming unit20Y. Hereinafter, for the sake of description, a direction orthogonal to the conveyance direction of the roll paper R is referred to as a front-back direction. A direction from a back surface toward a front surface is referred to as a direction to the front, and a direction from the front surface to the back surface is referred to as a direction to the back.

With reference toFIGS.2to5, the image forming unit20Y includes the bottle storage40Y, the first toner storage50Y, and the second toner storage60Y. The bottle storage40Y, the first toner storage50Y, and the second toner storage60Y are arranged in this order on a path through which the toner is conveyed. The bottle storage40Y is arranged on a most upstream side, and the second toner storage60Y is arranged on a most downstream side. The second toner storage60Y is arranged immediately before the developing device21Y. The toner is supplied from the second toner storage60Y to the developing device21Y via a toner conveyance path.

More specifically, the bottle storage40Y, the first toner storage50Y, and the second toner storage60Y are arranged in this order in the conveyance direction of the roll paper R. The bottle storage40Y and the first toner storage50Y are connected to each other by a first conveyance path70Y. The first toner storage50Y and the second toner storage60Y are connected to each other by a second conveyance path80Y.

The bottle storage40Y extends in a rectangular tube shape in one direction and is arranged such that a longitudinal direction thereof is horizontal and parallel to the front-back direction. The bottle storage40Y includes an internal space in which the toner bottle30Y can be stored. The bottle storage40Y has an opening that opens the internal space to the outside on a side surface on a front side.

The toner bottle30Y includes a body portion31Y, a tapered portion32Y, and a gripped portion33Y The body portion31Y extends in a substantially cylindrical shape and includes a bottom34Y at one end. The tapered portion32Y extends from the other end of the body portion31Y toward the gripped portion33Y so as to be gradually smaller in diameter. The gripped portion33Y extends in a cylindrical shape from a tip end of the tapered portion32Y and includes a ceiling35Y at one end. A fitting groove36Y is formed on the ceiling35Y. An opening38Y opened to the outside is formed in a cylindrically extending portion of the gripped portion33Y.

An axial center of the toner bottle30Y is referred to as a center line CL, and a direction orthogonal to the center line CL is referred to as a radial direction. In this example, the toner bottle30Y is attached to the bottle storage40Y in a state in which the center line CL is horizontal. The toner bottle30Y includes an inner peripheral surface extending from the bottom34Y toward the ceiling35Y about the center line CL. The toner bottle30Y includes a protrusion37Y that protrudes inward from the inner peripheral surface and extends spirally about the center line CL from the bottom34Y to the opening38Y.

The bottle storage40Y includes a bottle rotating mechanism41Y. The bottle rotating mechanism41Y includes a bottle motor42Y, a gripping member43Y, and a guide member44Y. The guide member44Y extends in a cylindrical shape and includes one end fixed to a side wall on a back side of the bottle storage40Y in the internal space of the bottle storage40Y. The other end side of the guide member44Y forms an opening that opens an internal space of the guide member44Y to the outside. On the guide member44Y, an opening45Y that opens the internal space of the guide member44Y downward is formed in a portion extending in a cylindrical shape.

The bottle motor42Y is fixed to the side wall on the back side of the bottle storage40Y in the internal space of the guide member44Y The gripping member43Y is connected to a tip end of a rotating shaft of the bottle motor42Y A fitting claw is formed on a surface on a front side of the gripping member43Y.

The toner bottle30Y is detachably attached to the bottle storage40Y. The toner bottle30Y is inserted from the opening on the front side of the bottle storage40Y toward the internal space of the bottle storage40Y in a horizontal state. The ceiling35Y of the toner bottle30Y enters the internal space of the bottle storage40Y toward the back side. When the toner bottle30Y further enters, the ceiling35Y enters the internal space of the guide member44Y, and the fitting claw formed on the gripping member43Y fits into the fitting groove36Y formed on the ceiling35Y of the toner bottle30Y.

A rotational force of the bottle motor42Y is transmitted to the toner bottle30Y in a state in which the fitting claw formed on the gripping member43Y is fitted into the fitting groove36Y. Therefore, the bottle motor42Y rotates the toner bottle30Y. An inner diameter of the guide member44Y is set to be equal to or slightly larger than an outer diameter of the gripped portion33Y of the toner bottle30Y As a result, the toner bottle30Y rotates while sliding on an inner peripheral surface of the guide member44Y, so that the toner bottle30Y can be smoothly rotated about the center line CL thereof.

Positions of the opening45Y formed on the guide member44Y and the opening38Y formed on the gripped portion33Y of the toner bottle30Y are determined such that distances in a horizontal direction from the side wall on the back side of the bottle storage40Y become the same in a state in which the fitting claw formed on the gripping member43Y is fitted into the fitting groove36Y.

The first conveyance path70Y conveys the toner supplied from the toner bottle30Y to the first toner storage50Y The first conveyance path70Y includes a tubular member71Y, a first conveyance screw72Y, and a first conveyance motor75Y. The first conveyance motor75Y is a DC motor. Therefore, a cost of the first conveyance motor75Y can be reduced. The tubular member71Y has a shape extending in a tube shape in the conveyance direction of the roll paper R and in an upward direction and includes one end arranged below the guide member44Y and the other end positioned above the first toner storage50Y. On the tubular member71Y, a first reception port73Y is formed as an opening that opens an internal space thereof upward at a lower position facing the opening45Y formed on the guide member44Y. Therefore, the opening45Y and the first reception port73Y overlap with each other in plan view. A gap is formed between the opening45Y formed on the guide member44Y and the first reception port73Y formed on the tubular member71Y On the tubular member71Y, a first supply port74Y, which is an opening that opens the internal space thereof downward, is formed at an end on a side opposite to the end at which the first reception port73Y is formed.

On the toner bottle30Y, the protrusion37Y extending spirally about the center line CL is formed on the inner peripheral surface thereof. Therefore, when the toner bottle30Y is rotated by the bottle rotating mechanism41Y, the toner in the toner bottle30Y is conveyed backward by the protrusion37Y A part of the toner that reaches the gripped portion33Y is discharged to the outside from the opening38Y formed on the gripped portion33Y The toner discharged from the opening38Y falls into the internal space of the tubular member71Y via the opening45Y formed on the guide member44Y, the gap, and the first reception port73Y formed on the tubular member71Y.

The first conveyance screw72Y includes a rotating shaft extending in one direction and a blade, which is a protrusion extending spirally from one end to the other end about an axial center of the rotating shaft. The first conveyance screw72Y is rotatably stored in the internal space of the tubular member71Y such that the axial center thereof overlaps with an axial center of the tubular member71Y. An outer diameter of the first conveyance screw72Y is the same as or slightly smaller than an inner diameter of the tubular member71Y The first conveyance screw72Y is connected to a first conveyance motor75Y via a gear, and a rotational force of the first conveyance motor75Y is transmitted to the first conveyance screw72Y.

When the first conveyance screw72Y is rotated by the first conveyance motor75Y, the toner received from the first reception port73Y formed on the tubular member71Y is conveyed in the internal space of the tubular member71Y in a direction from the end at which the first reception port73Y is formed toward the end at which the first supply port74Y is formed of the tubular member71Y, and falls from the first supply port74Y.

The first toner storage50Y includes a housing including an internal space for storing the toner. The housing extends in a rectangular tube shape in one direction and is arranged such that a longitudinal direction thereof is horizontal and parallel to the front-back direction. An opening55Y that opens the internal space upward is formed on the housing. The internal space is communicated with the internal space of the first conveyance path70Y via the opening55Y and the first supply port74Y The first toner storage50Y includes a first supply motor51Y, a first supply screw52Y, two first stirring members53Y and54Y, and a first stirring motor59Y The first supply screw52Y includes a rotating shaft extending parallel to the front-back direction and a blade, which is a protrusion extending spirally from one end to the other end about an axial center of the rotating shaft. The first supply screw52Y is arranged substantially at the center in the conveyance direction of the roll paper R at the bottom of the internal space of the housing.

Each of the two first stirring members53Y and54Y includes a rotating shaft extending parallel to the front-back direction and a plurality of stirring plates. The plurality of stirring plates is dispersedly arranged in a rotating shaft direction and extends in a plate shape perpendicularly from the rotating shaft. A plurality of holes is formed on the plurality of stirring plates.

Each of the two first stirring members53Y and54Y is arranged above the first supply screw52Y such that the rotating shaft thereof is parallel to the rotating shaft of the first supply screw52Y The two first stirring members53Y and54Y are arranged with the first supply screw52Y interposed therebetween in plan view.

In the housing of the first toner storage50Y, an inner surface of a bottom thereof has a shape in which parts of side surfaces of three cylinders are arranged in parallel. In the housing of the first toner storage50Y, in a cross section in a plane parallel to the conveyance direction of the roll paper R, the inner surface of the bottom includes a part of a circle centered on the rotating shaft of the first supply screw52Y and parts of circles centered on the rotating shafts of the two first stirring members53Y and54Y, respectively.

At the bottom of the housing of the first toner storage50Y, the first discharge port58Y that opens the internal space thereof downward is formed at an end on a back side. The first discharge port58Y overlaps with a part of the first supply screw52Y in plan view.

The first supply screw52Y is connected to the first supply motor51Y via a gear, and a rotational force of the first supply motor51Y is transmitted to the first supply screw52Y. Each of the two first stirring members53Y and54Y is connected to the first stirring motor59Y via a gear, and a rotational force of the first stirring motor59Y is transmitted to the first stirring members53Y and54Y The two first stirring members53Y and54Y rotate in different directions.

When the two first stirring members53Y and54Y are rotated by the first stirring motor59Y, the toner stored in the internal space of the first toner storage50Y is stirred by the two first stirring members53Y and54Y. When the first supply screw52Y is rotated by the first supply motor51Y, the toner in the vicinity of the bottom of the internal space out of the toner stored in the internal space of the first toner storage50Y is conveyed in a direction from the front toward the back and falls from the first discharge port58Y.

The first supply motor51Y and the first stirring motor59Y are DC motors. Therefore, a cost of the first supply motor51Y and the first stirring motor59Y can be reduced.

The second conveyance path80Y conveys the toner supplied from the first toner storage50Y to the second toner storage60Y The second conveyance path80Y includes a tubular member81Y, a second conveyance screw82Y, and a second conveyance motor85Y. The second conveyance motor85Y is a DC motor. Therefore, a cost of the second conveyance motor85Y can be reduced. The tubular member81Y has a shape extending in a tube shape in the conveyance direction of the roll paper R and in an upward direction and includes one end arranged below the first toner storage50Y and the other end positioned above the second toner storage60Y On the tubular member81Y, a second reception port83Y is formed as an opening that opens an internal space thereof upward at a lower position facing the first discharge port58Y formed on the housing of the first toner storage50Y Therefore, the first discharge port58Y and the second reception port83Y overlap with each other in plan view. A gap is formed between the first discharge port58Y formed on the housing of the first toner storage50Y and the second reception port83Y formed on the tubular member81Y On the tubular member81Y, a second supply port84Y, which is an opening that opens the internal space thereof downward, is formed at an end on a side opposite to the end at which the second reception port83Y is formed.

The second conveyance screw82Y includes a rotating shaft extending in one direction and a blade, which is a protrusion extending spirally from one end to the other end about an axial center of the rotating shaft. The second conveyance screw82Y is rotatably stored in the internal space of the tubular member81Y such that the axial center thereof overlaps with an axial center of the tubular member81Y. An outer diameter of the second conveyance screw82Y is the same as or slightly smaller than an inner diameter of the tubular member81Y. The second conveyance screw82Y is connected to a second conveyance motor85Y via a gear, and a rotational force of the second conveyance motor85Y is transmitted to the second conveyance screw82Y.

When the second conveyance screw82Y is rotated by the second conveyance motor85Y, the toner received from the second reception port83Y formed on the tubular member81Y is conveyed in the internal space of the tubular member81Y in a direction from the end at which the second reception port83Y is formed toward the end at which the second supply port84Y is formed of the tubular member81Y, and falls from the second supply port84Y.

FIG.6is a perspective view of the second toner storage. With reference toFIGS.2,3, and6, the second toner storage60Y includes a housing including an internal space in which the toner is stored having a rectangular shape elongated in one direction in plan view. An opening65Y that opens the internal space upward is formed on the housing. The internal space is communicated with the internal space of the second conveyance path80Y via the opening65Y and the second supply port84Y In this embodiment, the second toner storage60Y is arranged such that a longitudinal direction thereof is parallel to the conveyance direction of the roll paper R. The second toner storage60Y includes a second supply motor61Y, a second supply screw62Y, and two second stirring members63Y and64Y The second supply screw62Y includes a rotating shaft extending parallel to the longitudinal direction of the internal space and a blade, which is a protrusion extending spirally from one end to the other end about an axial center of the rotating shaft. The second supply screw62Y is arranged substantially at the center in the front-back direction at the bottom of the internal space.

Each of the two second stirring members63Y and64Y includes a rotating shaft extending parallel to the longitudinal direction of the internal space and a plurality of stirring plates. The plurality of stirring plates is dispersedly arranged in a rotating shaft direction and extends in a plate shape perpendicularly from the rotating shaft. A plurality of holes is formed on the plurality of stirring plates.

Each of the two second stirring members63Y and64Y is arranged above the second supply screw62Y such that the rotating shaft thereof is parallel to the rotating shaft of the second supply screw62Y The two second stirring members63Y and64Y are arranged with the second supply screw62Y interposed therebetween in plan view.

In the housing of the second toner storage60Y, an inner surface of a bottom thereof has a shape in which parts of side surfaces of three cylinders are arranged in parallel. In the housing of the second toner storage60Y, in a cross section in a plane perpendicular to the conveyance direction of the roll paper R, the inner surface of the bottom includes a part of a circle centered on the rotating shaft of the second supply screw62Y and parts of circles centered on the rotating shafts of the two second stirring members63Y and64Y, respectively.

At the bottom of the housing of the second toner storage60Y, the second discharge port68Y that opens the internal space thereof downward is formed at the end on the side opposite to the opening65Y in the conveyance direction of the roll paper R. The second discharge port68Y overlaps with a part of the second supply screw62Y in plan view.

A reception port211Y, which is an opening that opens the internal space outward, is formed on the developing device21Y The second discharge port68Y overlaps with the reception port211Y formed on the developing device21Y in plan view. A gap is formed between the second discharge port68Y and the reception port211Y below the second discharge port68Y The toner discharged from the second discharge port68Y enters the internal space of the developing device21Y from the reception port211Y via the gap. The gap between the second discharge port68Y and the reception port211Y is a toner conveyance path.

The second supply screw62Y is connected to the second supply motor61Y via a gear, and a rotational force of the second supply motor61Y is transmitted to the second supply screw62Y Each of the two second stirring members63Y and64Y is connected to the second stirring motor69Y via a gear, and a rotational force of the second stirring motor69Y is transmitted to the second stirring members63Y and64Y. The two second stirring members63Y and64Y rotate in different directions.

When the two second stirring members63Y and64Y are rotated by the second stirring motor69Y, the toner stored in the internal space of the second toner storage60Y is stirred by the two second stirring members63Y and64Y When the second supply screw62Y is rotated by the second supply motor61Y, the toner in the vicinity of the bottom of the internal space out of the toner stored in the internal space of the second toner storage60Y is conveyed in the conveyance direction of the roll paper R by the second supply screw62Y and falls from the second discharge port68Y to the developing device21Y.

The second supply motor61Y is a stepping motor. Therefore, a rotation amount of the second supply screw62Y can be adjusted by controlling a rotation amount of the second supply motor61Y, so that an amount of toner falling into the developing device21Y can be accurately adjusted. The second stirring motor69Y is a DC motor. Therefore, a cost of the second stirring motor69Y can be reduced.

In this embodiment, a toner capacity storable in the first toner storage50Y is larger than a toner capacity storable in the second toner storage60Y. The toner capacity is a weight of the toner storable in the internal space. The toner capacity storable in the second toner storage60Y is equal to or larger than a toner capacity storable in the developing device21Y. Therefore, even in a case where the toner is rapidly consumed in the developing device21Y, an appropriate amount of toner can be supplied to the developing device21Y, and toner density in the developing device21Y can be maintained constant. The toner capacity storable in the first toner storage50Y is equal to or larger than 10% of a toner capacity storable in the toner bottle30Y. More preferably, the toner capacity storable in the first toner storage50Y is equal to or larger than 50% of the toner capacity storable in the toner bottle30Y. Therefore, the internal space of the image forming apparatus1does not become too large and can be effectively used. It is possible to secure a sufficient time for replacing the toner bottle30Y with a new toner bottle30Y after the toner bottle30Y becomes empty.

The toner capacity storable in the first toner storage50Y may be a capacity with which it is possible to continuously print on the roll paper R of 1,000 m or longer at a predetermined printing rate in the developing device21Y The printing rate is a ratio of an area in which the toner image is formed per unit area. In a case where there is a plurality of types of roll paper R having different widths, the toner capacity storable in the first toner storage50Y is determined based on the roll paper R having the maximum width. Since the amount of toner consumed per unit area can be calculated from the printing rate, the toner capacity storable in the first toner storage50Y is obtained from the area determined by the width of the roll paper R and the length of the roll paper R and a toner consumption amount per unit area. The predetermined printing rate is preferably 15%. Furthermore, the total toner capacity storable in the toner bottle30Y, the first toner storage50Y, and the second toner storage60Y is preferably a capacity with which it is possible to print on continuous paper by 3,000 m or longer.

In order to keep the toner density in the developing device21Y constant, it is necessary to accurately and precisely supply the toner of an amount corresponding to the amount of toner consumed in the developing device21Y to the developing device21Y. In this embodiment, the amount of toner to be supplied to the developing device21Y can be accurately adjusted by using a stepping motor capable of controlling with high accuracy as the second supply motor61Y included in the second toner storage60Y arranged immediately before the developing device21Y The first toner storage50Y on an upstream side of the second toner storage60Y has a larger toner storage amount than that of the second toner storage60. Therefore, the first supply motor51Y included in the first toner storage50Y is a DC motor. The DC motor has a larger torque than that of the stepping motor. By using the DC motor (other than the stepping motor) as the first supply motor51Y, the driving can be stably controlled even in a case where a load is large. Since the first toner storage50Y and the second toner storage60Y share their roles, it is possible to achieve both maintenance in image quality and productivity with roll paper.

<Toner Conveyance Control>

With reference toFIGS.3and5, the first toner storage50Y includes an upper limit sensor56Y and a lower limit sensor57Y in the internal space. The upper limit sensor56Y is arranged above the lower limit sensor57Y. The lower limit sensor57Y is arranged at the same height as an upper surface of the toner in a state in which the toner of half the toner amount storable in the first toner storage50Y is stored in the first toner storage50Y As a result, it is possible to detect that the toner stored in the first toner storage50Y is half from an output of the lower limit sensor57Y The upper limit sensor56Y and the lower limit sensor57Y output an ON signal to the controller90when detecting the toner and output an OFF signal to the controller90while the toner is not detected. The upper limit sensor56Y and the lower limit sensor57Y are, for example, piezoelectric elements. Therefore, while the upper limit sensor56Y outputs the ON signal, the lower limit sensor57Y outputs the ON signal. While the upper limit sensor56Y outputs the OFF signal, the lower limit sensor57Y outputs the ON signal or the OFF signal.

With reference toFIGS.3and6, the second toner storage60Y includes a toner sensor66Y in the internal space. The toner sensor66Y outputs an ON signal to the controller90when detecting the toner, and outputs an OFF signal to the controller90while the toner is not detected. The toner sensor66Y is, for example, a piezoelectric element.

The developing device21Y stores a developer including a carrier and toner. Atoner density sensor SEY (refer toFIG.2) is arranged in a space in which the developer is stored of the developing device21Y The toner density sensor SEY detects the toner density of the developer. The toner density is a ratio of the toner to the carrier.

The controller90controls the bottle storage40Y, the first toner storage50Y, the second toner storage60Y, the first conveyance path70Y, and the second conveyance path80Y, and adjusts the amount of toner stored in the developing device21Y to be appropriate.

The controller90controls the bottle storage40Y and the first conveyance path70Y based on the outputs of the upper limit sensor56Y and the lower limit sensor57Y and adjusts the amount of toner stored in the first toner storage50Y to be appropriate. Processing in which the controller90controls the bottle storage40Y and the first conveyance path70Y is referred to as first control processing. The controller90controls the first toner storage50Y and the second conveyance path80Y based on the output of the toner sensor66Y and adjusts the amount of toner stored in the second toner storage60Y to be appropriate. Processing in which the controller90controls the first toner storage50Y and the second conveyance path80Y is referred to as second control processing. The controller90controls the second toner storage60Y based on the output of the toner density sensor SEY included in the developing device21Y and adjusts the density of toner stored in the developing device21Y to be appropriate. Processing in which the controller90controls the second toner storage60Y is referred to as third control processing.

The controller90executes the first control processing, the second control processing, and the third control processing while executing the job received from the outside. In other words, the controller90can execute processing of executing the job received from the outside, the first control processing, the second control processing, and the third control processing in parallel.

FIG.7is a flowchart illustrating an example of a flow of the first control processing. The first control processing is processing executed by the controller90when the CPU included in the controller90executes a control program stored in the memory. With reference toFIG.7, the controller90determines whether the output of the upper limit sensor56Y changes from the ON signal to the OFF signal (step S01). While the upper limit sensor56Y outputs the ON signal, a standby state is set (NO at step S01), and when the upper limit sensor56Y outputs the OFF signal (YES at step S01), the processing shifts to step S02.

At step S02, the first conveyance motor75Y and the bottle motor42Y are driven, and the processing shifts to step S03. As a result, the toner bottle30Y rotates, so that the toner is supplied from the toner bottle30Y to the first conveyance path70Y Since the first conveyance screw72Y rotates, the toner supplied from the toner bottle30Y to the first conveyance path70Y is conveyed by the first conveyance screw72Y to be supplied to the first toner storage50Y.

At step S03, it is determined whether the output of the upper limit sensor56Y changes from the OFF signal to the ON signal. When the ON signal is output from the upper limit sensor56Y, the processing shifts to step S04, and otherwise, the processing shifts to step S05. While the OFF signal is output from the upper limit sensor56Y, the processing shifts to step S05.

At step S04, the first conveyance motor75Y and the bottle motor42Y are stopped, and the processing ends. As a result, the toner bottle30Y stops rotating, so that the toner is no more supplied from the toner bottle30Y to the first conveyance path70Y, and the first conveyance screw72Y stops rotating, so that the toner is no more supplied to the first toner storage50Y. Therefore, the toner stored in the first toner storage50Y is kept at a height equal to or higher than the height at which the upper limit sensor56Y is installed.

At step S05, it is determined whether the output of the lower limit sensor57Y changes from the ON signal to the OFF signal. When the OFF signal is output from the lower limit sensor57Y (YES at step S05), the processing shifts to step S06, and otherwise, the processing returns to step S03. In a case where the ON signal is output from the lower limit sensor57Y while the OFF signal is output from the upper limit sensor56Y, the toner stored in the first toner storage50Y is half or more. In this case, the processing returns to step S03, and the first conveyance motor75Y and the bottle motor42Y are continuously driven until the upper limit sensor56Y outputs the ON signal.

In contrast, in a case where the OFF signal is output from the lower limit sensor57Y while the OFF signal is output from the upper limit sensor56Y, the toner stored in the first toner storage50Y is less than half. In this case, the processing shifts to step S06.

At step S06, notification is made that the toner bottle30Y becomes empty and that the amount of toner stored in the first toner storage50Y is half or less. For example, a message prompting replacement of the toner bottle30Y and a message indicating that the amount of toner stored in the first toner storage50Y is half or less are displayed on a display device included in the image forming apparatus1. Sound may be generated from a speaker. For example, the message may be output by voice. Notification may be made by light by causing an LED and the like to emit light.

At subsequent step S07, it is determined whether the output of the lower limit sensor57Y changes from the OFF signal to the ON signal. When the ON signal is output from the lower limit sensor57Y (YES at step S07), the processing shifts to step S08, and otherwise, the processing returns to step S06. At step S08, the controller90ends the notification and the procedure returns to step S03. A case where the output of the lower limit sensor57Y changes from the OFF signal to the ON signal is a case where the amount of toner stored in the first toner storage50Y increases. In this case, the toner is supplied from the toner bottle30Y, so that the first conveyance motor75Y and the bottle motor42Y are continuously driven until the upper limit sensor56Y outputs the ON signal. In contrast, in a case where the output of the lower limit sensor57Y does not change from the OFF signal to the ON signal, the notification is continued. Since the toner is continuously consumed by the developing device21Y, if the toner bottle30Y is not replaced, the toner stored in the first toner storage50Y decreases. A time for replacing the toner bottle30Y is secured by a period until entire toner stored in the first toner storage50Y is consumed by the developing device21Y.

FIG.8is a flowchart illustrating an example of a flow of the second control processing. The second control processing is processing executed by the controller90when the CPU included in the controller90executes a control program stored in the memory. With reference toFIG.8, the controller90determines whether the output of the toner sensor66Y changes from the ON signal to the OFF signal (step S11). While the toner sensor66Y outputs the ON signal, a standby state is set (NO at step S11), and when the toner sensor66Y outputs the OFF signal (YES at step S11), the processing shifts to step S12.

At step S12, the second conveyance motor85Y and the first supply motor51Y are driven, and the processing shifts to step S13. As a result, the first supply screw52Y rotates, so that the toner is supplied from the first toner storage50Y to the second conveyance path80Y. The second conveyance screw82Y rotates, so that the toner supplied from the first toner storage50Y to the second conveyance path80Y is supplied to the second toner storage60Y.

At step S13, it is determined whether the output of the toner sensor66Y changes from the OFF signal to the ON signal. When the ON signal is output from the toner sensor66Y, the processing shifts to step S14, and otherwise, the processing returns to step S13. While the OFF signal is output from the toner sensor66Y, the second conveyance motor85Y and the first supply motor51Y are continuously driven.

At step S14, the second conveyance motor85Y and the first supply motor51Y are stopped, and the processing ends. As a result, the first supply screw52Y stops rotating, so that the toner is no more supplied from the first toner storage50Y to the second conveyance path80Y, and the second conveyance screw82Y stops rotating, so that the toner is no more supplied to the second toner storage60Y. Therefore, the toner stored in the second toner storage60Y is kept at a height equal to or higher than the height at which the toner sensor66Y is installed.

FIG.9is a flowchart illustrating an example of a flow of the third control processing. The third control processing is processing executed by the controller90when the CPU included in the controller90executes a control program stored in the memory. With reference toFIG.9, the controller90compares the toner density with a threshold TH (step S21). The toner density is detected based on an output value of the toner density sensor SEY. When the toner density is equal to or larger than the threshold TH, a standby state is set (NO at step S21), and when the toner density is smaller than the threshold TH (YES at step S21), the processing shifts to step S22. In a case where the toner density is smaller than the threshold TH, the amount of toner stored in the developing device21Y is smaller than a target toner amount.

At step S22, the second supply motor61Y is driven, and the processing shifts to step S23. As a result, the second supply screw62Y rotates, so that the toner is supplied from the second toner storage60Y to the developing device21Y.

At step S23, the toner density is compared with the threshold TH. When the toner density is smaller than the threshold TH, the processing shifts to step S25, and when the toner density is equal to or larger than the threshold TH, the processing shifts to step S24. While the toner density is smaller than the threshold TH, the second supply motor61Y is continuously driven.

At step S24, the second supply motor61Y is stopped, and the processing ends. As a result, the second supply screw62Y stops rotating, so that the toner is no more supplied from the second toner storage60Y to the developing device21Y. Therefore, the toner density of the developer stored in the developing device21Y is kept constant.

At step S25, it is determined whether a predetermined time elapses since it is determined that the toner density is smaller than the threshold TH. When a predetermined time elapses, the processing shifts to step S26, and otherwise, the processing returns to step S23. At step S26, driving of the image former IM is stopped, and the processing ends. A case where a predetermined time elapses after the toner density is determined to be smaller than the threshold TH is a case where the toner is not supplied from the first toner storage50Y to the second toner storage60Y Since this case corresponds to a case where the toner bottle30Y is not replaced, the image former IM is stopped so that an image forming operation is not executed in a state in which there is no toner in the second toner storage60Y.

As described above, the image forming apparatus1according to this embodiment can form the toner image on the roll paper R, which is continuous paper. The image forming apparatus1includes the developing device21Y that develops the latent image formed on the photosensitive drum22Y to form the toner image, the toner bottle30Y that stores the toner and is detachably attached to the main body11, and the first toner storage50Y and the second toner storage60Y, and the toner is supplied from the toner bottle30Y to the developing device21Y via the first toner storage50Y and the second toner storage60Y. Therefore, even in a state in which the toner stored in the toner bottle30Y runs out, the toner is stored in the first toner storage50Y and the second toner storage60Y Even in a state in which the toner stored in the toner bottle30Y runs out, the toner stored in the first toner storage50Y and the second toner storage60Y is supplied to the developing device21Y, so that the toner image can be continuously formed on the roll paper R. Therefore, it is possible to secure a time for replacing the toner bottle30Y with a new toner bottle30Y after the toner in the toner bottle30Y runs out. Therefore, it is not necessary to increase a size of the toner bottle30Y. The toner image can be continuously formed on the roll paper R without stopping the image forming operation.

The toner capacity of the first toner storage50Y is larger than the toner capacity of the second toner storage60Y Therefore, a size of the second toner storage60Y can be reduced, and space saving, and power saving can be achieved. The toner storage amount in the entire image forming apparatus1can be improved, and the toner can be accurately supplied to the developing device21Y in order to maintain the toner density of the developing device21Y.

The toner is supplied from the first toner storage50Y on the upstream side to the developing device21Y via the second toner storage60Y on the downstream side. Therefore, the direction in which the toner is conveyed is one direction, so that the path through which the toner is conveyed can be shortened.

The first toner storage50Y on the upstream side stores the toner supplied from the toner bottle30Y, and the second toner storage60Y on the downstream side stores the tonner conveyed from the first toner storage50Y on the upstream side and supplies the toner to the developing device21Y according to the toner density in the developing device21Y. Therefore, even when the toner bottle30Y becomes empty, the first toner storage50Y can supply the toner to the second toner storage60Y Even when the first toner storage50Y becomes empty, the second toner storage60Y can supply the toner to the developing device21Y Therefore, it is possible to secure a time from when the toner bottle30Y becomes empty until the second toner storage60Y becomes unable to supply the toner to the developing device21Y.

Each of the first toner storage50Y and the second toner storage60Y may store the toner supplied from the outside during the job and may convey the toner to the outside during the job. Therefore, the toner is supplied from the toner bottle30Y to the developing device21Y while the job defining processing of forming the toner image on the roll paper R is being executed in the image forming apparatus1. Therefore, the toner image can be formed on the roll paper R without interrupting the job.

The second toner storage60Y on the upstream side of the developing device21Y has the toner capacity equal to or larger than the toner capacity of the developing device21Y. Therefore, even in a case where the toner is rapidly consumed in the developing device21Y, an appropriate amount of toner can be supplied to the developing device21Y, and toner density in the developing device21Y can be maintained constant.

A value obtained by summing up the toner capacities of the first toner storage50Y and the second toner storage60Y is equal to or larger than the toner capacity of the developing device21Y Therefore, it is possible to secure a time for replacing the toner bottle30Y while maintaining the toner density in the developing device21Y constant.

The first toner storage50Y and the second toner storage60Y have different driving sources. The toner is independently supplied in each of the first toner storage50Y and the second toner storage60Y Therefore, the control of supplying the toner in each of the first toner storage50Y and the second toner storage60Y may be made different.

Although embodiments of the present invention have been described and illustrated in detail, the disclosed embodiments are made for purposes of illustration and example only and not limitation. The scope of the present invention should be interpreted by terms of the appended claims.