JP2022126883A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can determine a near-empty state of a toner container at an appropriate timing.

SOLUTION: A toner contained in a toner container 41 is supplied to a developing device 33 through an intermediate hopper 43. A toner sensor 49 detects a toner empty state on the upstream side of a conveying screw 47 of the intermediate hopper 43 in the direction of conveyance of toner. A control unit 8 drives a rotation mechanism 45 such that every time the toner sensor 49 detects the empty state, the toner is discharged from the toner container 41. The control unit 8 calculates the amount of conveyed toner conveyed from the intermediate hopper 43 during a period from when the toner sensor 49 detects the empty state until when it detects the empty state again, on the basis of the history of the drive of a motor for conveyance 77. When the calculated amount of conveyed toner is equal to or less than a first conveyance amount threshold continuously for a plurality of times, the control unit 8 determines that the toner container 41 is in a near empty state.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to an image forming apparatus having a toner replenishing device that replenishes toner to a developing device.

The image forming apparatus described in Patent Document 1 has a toner container, an intermediate hopper, a developing device, and a control section. The toner stored in the toner container is supplied to the developing device through the intermediate hopper. The controller measures the time from when the toner container starts supplying the toner to the intermediate hopper until the remaining amount of toner in the intermediate hopper reaches a predetermined amount. The controller estimates the remaining amount of toner in the toner container based on the measured time.

JP 2008-304822 A

The image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 2002-200330 has a problem that the remaining amount of toner in the toner container cannot be accurately estimated when the capacity of the intermediate hopper is small. As a result, if the near-empty determination of the toner container is delayed, the user cannot secure enough time to prepare a new toner container, resulting in downtime of the image forming apparatus.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an image forming apparatus capable of making a near-empty determination for a toner container at an appropriate timing.

An image forming apparatus of the present invention includes a developing device, a toner container, an intermediate transport path, a first transport section, a second transport section, a first detection section, and a control section. The developing device develops the electrostatic latent image into a toner image. The toner container accommodates toner to be replenished to the developing device. Toner is supplied from the toner container to the intermediate conveying path. The first transport section transports toner from the toner container to the intermediate transport path, and the second transport section transports toner from the intermediate transport path to the developing device. The first detection section detects empty toner on the upstream side in the toner conveying direction of the second conveying section. The control section controls the first conveying section and the second conveying section independently of each other. The control unit drives the first conveying unit for a first drive time each time the first detection unit detects empty. Based on the driving history of the second conveying unit, the control unit determines the amount of toner conveyed from the intermediate conveying path during the period from when the first detecting unit detects the empty state to when the empty state is detected again. calculated by The controller determines that the toner container is near empty when the calculated toner transport amount is equal to or less than a first transport amount threshold for a plurality of consecutive times.

Another image forming apparatus of this torch includes a developing device, a toner container, a transport section, a detection section, and a control section. The developing device develops the electrostatic latent image into a toner image. The toner container accommodates toner to be replenished to the developing device. The transport unit transports toner from the toner container to the developing device. The detection unit detects the concentration of toner in the developing device. The control section controls the transport section. The control section drives the conveying section for a first drive time each time the detecting section detects that the density of toner in the developing device has decreased below a predetermined value. The control unit calculates the amount of toner transported from the toner container from the time when the detection unit detects the decrease in density until the time when the detection unit detects the decrease in density again, from the electrostatic latent image formation information. calculate. The controller determines that the toner container is near empty when the calculated toner transport amount is equal to or less than a first transport amount threshold for a plurality of consecutive times.

According to the above-described image forming apparatus of the present invention, it is possible to perform the near-empty determination of the toner container at appropriate timing.

1 is a diagram illustrating an example of an image forming apparatus according to a first embodiment; FIG. 1 is a diagram showing an example of a toner replenishing device according to a first embodiment; FIG. It is a figure which shows an example of the control part which concerns on 1st Embodiment. 5 is a diagram showing an example of the relationship between the amount of toner remaining in a toner container and the amount of toner conveyed to a developing device; FIG. 5 is a diagram showing an example of the relationship between the amount of toner remaining in a toner container and the amount of toner conveyed to a developing device; FIG. 6 is a flowchart showing an example of processing of a control unit; 6 is a flowchart showing an example of processing of a control unit; 6 is a flowchart showing an example of processing of a control unit; 6 is a flowchart showing an example of processing of a control unit; 6 is a flowchart showing an example of processing of a control unit; FIG. 10 is a diagram showing an example of a toner replenishing device according to a second embodiment; It is a figure which shows an example of the control part which concerns on 2nd Embodiment. 6 is a flowchart showing an example of processing of a control unit; 6 is a flowchart showing an example of processing of a control unit; 6 is a flowchart showing an example of processing of a control unit;

Embodiments of the present invention will be described below with reference to FIGS. 1 to 15. FIG. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

[First embodiment]
First, an image forming apparatus 1 according to the first embodiment will be described with reference to FIGS. 1 and 2. FIG. FIG. 1 is a diagram showing an example of an image forming apparatus 1 according to the first embodiment. FIG. 2 is a diagram showing an example of the toner replenishing device 37 according to the first embodiment. The image forming apparatus 1 functions as a color printer.

As shown in FIG. 1, the image forming apparatus 1 includes a paper feed section 2, a toner image forming section 3, a transfer section 4, a fixing device 5, a paper discharge section 6, a paper transport path 7, and a controller. a part 8;

The paper feed unit 2 includes a paper feed cassette 11 that stores paper and a paper feed device 13 that feeds the paper from the paper feed cassette 11 to the transport path 7 .

The toner image forming section 3 has an exposure device 15 and a toner image forming unit 17 provided for each of the four colors, and forms a toner image of each color. The four colors are, for example, Y (yellow), M (magenta), C (cyan), and B (black).

The transfer section 4 has an intermediate transfer belt 19 , four primary transfer rollers 21 and a secondary transfer roller 23 . The four primary transfer rollers 21 primarily transfer the toner images of each color formed by the toner image forming section 3 onto the intermediate transfer belt 19 . A secondary transfer roller 23 secondarily transfers the full-color toner image from the intermediate transfer belt 19 onto a sheet.

The fixing device 5 fixes the secondary-transferred full-color toner image on the paper.

The paper discharge section 6 has a discharge device 25 and a discharge tray 27 . The discharging device 25 discharges the paper on which the full-color toner image is fixed. The discharge tray 27 receives the discharged paper.

A conveying path 7 extends from the paper feeding section 2 through the transfer section 4 and the fixing device 5 to the paper discharging section 6 .

The control unit 8 causes the paper feeding unit 2, the toner image forming unit 3, the transfer unit 4, the fixing device 5, and the paper discharging unit 6 to perform respective operations, and moves the paper along the transport path 7 so as to correspond to each operation. transport along.

Next, the toner image forming unit 17 will be described. The toner image forming unit 17 has a photosensitive drum 29 , a charging device 31 , a developing device 33 and a cleaning device 35 . The charging device 31 , the developing device 33 and the cleaning device 35 are arranged around the photosensitive drum 29 . The toner image forming unit 17 further has a toner supply device 37 for supplying toner to the developing device 33, as shown in FIG.

In the toner image forming unit 17, the photosensitive drum 29 is charged by the charging device 31 and then exposed by the exposure device 15 to form an electrostatic latent image. The developing device 33 has a toner supply port 33a as shown in FIG. 2, and develops the electrostatic latent image into a toner image using toner supplied by the toner supply device 37. The developing device 33 further has a toner density sensor 39 that detects the density D of toner in the developing device 33 . The toner density D indicates the ratio of the toner in the two-component developer containing the toner and the carrier. The toner concentration sensor 39 is electrically connected to the control section 8 and transmits detection results to the control section 8 . The cleaning device 35 shown in FIG. 1 removes toner remaining on the photosensitive drum 29 after the toner image is primarily transferred onto the intermediate transfer belt 19 . The toner density sensor 39 corresponds to an example of the "second detection section" and the "detection section".

As shown in FIG. 2, the toner supply device 37 includes a toner container 41, a toner container attaching/detaching portion 65, an intermediate hopper 43, a rotating mechanism 45, a conveying screw 47, a conveying motor 77, and a toner sensor 49. , and a rotation detection mechanism 51 .

The toner container 41 accommodates toner to be supplied to the developing device 33 . The toner container 41 has a bottle shape with a discharge port 61, and has a cylindrical body portion 41a and a neck portion 41b having a diameter smaller than that of the body portion 41a. A protrusion 63 protruding into the body portion 41a is spirally formed on the inner peripheral surface of the body portion 41a. A discharge port 61 is formed on the side surface of the neck portion 41b.

The toner container attaching/detaching portion 65 detachably supports the toner container 41 . The toner container 41 is attached/detached to/from the toner container attachment/detachment portion 65 in a lateral posture. As shown in FIG. 1, toner containers 41 for four colors are attached to the image forming apparatus 1 .

Toner is temporarily supplied from the toner container 41 to the intermediate hopper 43 . The intermediate hopper 43 has a storage section 67 , a horizontal conveying section 69 and a vertical conveying section 71 . The storage section 67 is arranged below the toner container 41 and extends in the vertical direction. The horizontal conveying portion 69 extends horizontally with one end communicating with the lower end of the storage portion 67 . The vertical conveying portion 71 communicates with the other end of the horizontal conveying portion 69 and extends downward along the vertical direction. An upper end opening of the storage portion 67 is connected to the toner container attaching/detaching portion 65 so as to be below the neck portion 41 b of the toner container 41 . A lower end opening of the vertical conveying portion 71 is connected to the toner supply port 33 a of the developing device 33 . The intermediate hopper 43 corresponds to an example of an "intermediate conveying path".

The rotating mechanism 45 conveys toner from the toner container 41 to the intermediate hopper 43 . The rotation mechanism 45 has a grip portion 73 that grips the neck portion 41 b of the toner container 41 and a supply motor 75 that rotates the grip portion 73 . When the supply motor 75 rotates the grip portion 73, the toner container 41 rotates. When the toner container 41 rotates, the toner stored in the body portion 41a is conveyed toward the neck portion 41b by the spiral protrusion 63 formed on the body portion 41a. The toner drops from the outlet 61 into the reservoir 67 of the intermediate hopper 43 when the outlet 61 of the neck portion 41b faces downward. The supply motor 75 is electrically connected to the controller 8, and is controlled by the controller 8 to rotate the toner container 41 at a constant rotational speed. The rotating mechanism 45 corresponds to an example of the "first transport section". The supply motor 75 corresponds to an example of a "first motor".

A conveying screw 47 conveys the toner from the intermediate hopper 43 to the developing device 33 . The conveying screw 47 is rotatably supported by the horizontal conveying section 69 . The toner in the horizontal conveying portion 69 is conveyed toward the vertical conveying portion 71 by the rotation of the conveying screw 47 . The conveying screw 47 corresponds to an example of a "second conveying section".

The transport motor 77 is electrically connected to the controller 8 and driven by the controller 8 to rotate the transport screw 47 at a constant rotational speed. The transport motor 77 corresponds to an example of a “second transport unit” and a “second motor”.

The toner sensor 49 detects empty toner on the upstream side of the conveying screw 47 in the toner conveying direction. The toner sensor 49 is provided below the reservoir 67 of the intermediate hopper 43 . The toner sensor 49 detects empty when the upper surface of the toner stored in the horizontal conveying portion 69 and the storage portion 67 decreases to the detection height H. FIG. As the toner sensor 49, a transmissive or reflective photosensor, a piezoelectric sensor, or the like can be used. The toner sensor 49 is electrically connected to the control section 8 and transmits to the control section 8 a detection result indicating whether or not it is empty. The toner sensor 49 corresponds to an example of the "first detection section".

The rotation detection mechanism 51 has a pulse plate 81 fixed to one end of the conveying screw 47 and a transmissive photosensor 83 . The pulse plate 81 is formed with a plurality of slits arranged at regular intervals in the circumferential direction. The transmissive photosensor 83 has a light-emitting portion and a light-receiving portion facing each other with the pulse plate 81 interposed therebetween. The transmissive photosensor 83 outputs a pulse waveform when the slit of the pulse plate 81 passes through the optical path between the light emitting portion and the light receiving portion. The transmissive photosensor 83 is electrically connected to the controller 8 . The controller 8 can calculate the number of revolutions of the conveying screw 47 by counting the pulse waveforms output from the transmissive photosensor 83 .

Next, the controller 8 according to the first embodiment will be described. FIG. 3 is a diagram showing an example of the control section 8. As shown in FIG.

As shown in FIG. 3 , the image forming apparatus 1 has a storage section 91 in addition to the control section 8 . The control unit 8 includes a processor such as a CPU (Central Processing Unit). The storage unit 91 includes a storage device and stores data and computer programs. The storage unit 91 includes a main storage device such as a semiconductor memory and an auxiliary storage device such as a semiconductor memory and/or a hard disk drive. The processor of the control section 8 controls each component of the image forming apparatus 1 by executing a computer program stored in the storage device of the storage section 91 .

As described above, the toner replenishing device 37 has the supply motor 75 , the transport motor 77 , the transmissive photosensor 83 , and the toner sensor 49 . The developing device 33 also has a toner density sensor 39 . The control unit 8 has an adjusting unit 101 , a calculating unit 102 and an estimating unit 103 . The processor of the control unit 8 is electrically connected to the supply motor 75, the transport motor 77, the transmissive photosensor 83, the toner sensor 49, and the toner concentration sensor 39, and functions as the adjustment unit 101, the calculation unit 102, and the estimation unit 103. Function.

The adjustment unit 101 adjusts the density D of toner in the developing device 33 by driving the transport motor 77 based on the detection result of the toner density sensor 39 . The toner density D should be kept constant. However, when the toner in the developing device 33 is consumed, the toner density D decreases. Therefore, the adjustment unit 101 drives the transport motor 77 to rotate the transport screw 47 so that the toner is transported from the intermediate hopper 43 to the developing device 33 when the toner density D becomes equal to or less than the threshold value TD1. As a result, the toner density D is kept substantially constant.

The calculation unit 102 calculates the transport amount Y of the toner transported from the intermediate hopper 43 from when the toner sensor 49 detects empty until it detects empty again, based on the drive history of the transport motor 77 . . As the driving history of the transport motor 77, the number of revolutions of the transport motor 77, that is, the number of revolutions of the transport screw 47 is used. Regarding the number of revolutions of the transport motor 77, the amount of toner transported per rotation of the transport screw 47 obtained by counting the pulse waveform output from the transmissive photosensor 83 by the calculator 102 is substantially constant. The calculation unit 102 calculates the toner transport amount Y for the same period based on the number of revolutions of the transport screw 47 during the period from when the toner sensor 49 detects the empty state to when it detects the empty state again.

The estimation unit 103 estimates the remaining amount (percentage) X of toner in the toner container 41 from the calculated toner transport amount Y. FIG.

4 and 5 are diagrams showing an example of the relationship between the toner remaining amount X and the toner conveying amount Y. FIG. In FIGS. 4 and 5, the horizontal axis indicates the remaining amount X of toner, and the vertical axis indicates the amount Y of toner conveyed. Each dot in FIGS. 4 and 5 represents an experimental result representing the relationship between the remaining amount of toner X and the amount Y of toner transported. A regression curve Y=F(X) is obtained from the experimental results. A regression curve Y=F(X) indicates that the toner conveying amount Y decreases as the toner remaining amount X decreases. The estimating unit 103 in FIG. 3 estimates the toner remaining amount X from the toner conveyed amount Y using the regression curve Y=F(X). The control unit 8 presents the toner gauge to the user based on the estimated remaining amount X of toner.

In FIGS. 4 and 5, values F(0) and F(100) are defined. The value F(0) is obtained by extrapolating the regression curve Y=F(X) to X=0%. The value F(100) is obtained by extrapolating the regression curve Y=F(X) to X=100%.

In FIG. 4, a first transport amount threshold TC1 and a second transport amount threshold TC2 are set. The first transport amount threshold TC1 is set smaller than the value F(0). For example, TC1=F(0)×0.5. Also, when X>20%, TC2=F(100)×1.5, and when X≦20%, TC2=F(0).

In FIG. 5, a first gauge threshold TG1, a second gauge threshold TG2, a third gauge threshold TG3, and a fourth gauge threshold TG4 are set. For example, TG1=30%, TG2=30%, TG3=10%, and TG4=20%. Note that TG1>TG2 may be satisfied.

Next, the processing of the control unit 8 will be described with reference to FIGS. 6 to 10. FIG. FIG. 6 is a flowchart showing an example of toner concentration adjustment processing by the control section 8. As shown in FIG. The toner density adjustment process is executed in steps S101 to S103.

Step S101: The controller 8 determines whether the toner density D detected by the toner density sensor 39 is equal to or less than the threshold value TD1. If the controller 8 determines that the toner density D is equal to or less than the threshold value TD1 (YES in step S101), the process of the controller 8 proceeds to step S103. If the control unit 8 determines that the toner density D is not equal to or less than the threshold value TD1 (NO in step S101), the processing of the control unit 8 ends.

Step S103: The controller 8 drives the transport motor 77 for a certain period of time so as to rotate the transport screw 47 . As a result, a substantially constant amount of toner is conveyed from the intermediate hopper 43 to the developing device 33 . After that, the processing of the control unit 8 returns to step S101.

In the toner density adjustment process of steps S101 to S103, the controller 8 controls the transport motor 77 based on the detection result of the toner density sensor 39. FIG. As a result, the toner density D in the developing device 33 is kept substantially constant.

7 and 8 are flowcharts showing an example of the near-empty determination processing of the control unit 8. FIG. The near-empty determination process is executed in steps S201 to S229.

Step S201: The controller 8 sets the flag F to zero. Flag F is a flag for confirming whether or not a specific event has occurred multiple times in succession.

Step S203: The controller 8 determines whether or not the toner transport amount Y is greater than or equal to the second transport amount threshold TC2. When the controller 8 determines that the toner transport amount Y is equal to or greater than the second transport amount threshold TC2 (YES in step S203), the process of the controller 8 proceeds to step S205. When the controller 8 determines that the toner transport amount Y is not equal to or greater than the second transport amount threshold TC2 (NO in step S203), the process of the controller 8 proceeds to step S207.

Step S205: The controller 8 calls a container rotation subroutine, which will be described later with reference to FIG. 10, so as to rotate the toner container 41. FIG. Specifically, the controller 8 drives the supply motor 75 for the first drive time. After the process of step S205 is completed, the process of the control unit 8 returns to step S203.

Step S207: Based on the detection result of the toner sensor 49, the controller 8 determines whether the intermediate hopper 43 is empty. When the control unit 8 determines that the intermediate hopper 43 is not empty (NO in step S207), the process of the control unit 8 returns to step S203. When the control unit 8 determines that the intermediate hopper 43 is empty (YES in step S207), the processing of the control unit 8 proceeds to step S209.

Step S209: The controller 8 calls a container rotation subroutine to rotate the toner container 41. FIG. Specifically, the controller 8 drives the supply motor 75 for the first drive time. After the process of step S209 is completed, the process of the control unit 8 proceeds to step S211.

Step S211: The controller 8 calculates the toner transport amount Y based on the integrated screw rotation speed data. After the process of step S211 is completed, the process of the control section 8 proceeds to step S213.

Step S213: The controller 8 estimates the remaining amount X of toner from the amount Y of toner transported. When the process of step S213 is finished, the process of the control section 8 proceeds to step S215 in FIG.

Step S215: The controller 8 determines whether or not the toner remaining amount X is equal to or less than the first gauge threshold value TG1. If the controller 8 determines that the toner remaining amount X is not equal to or less than the first gauge threshold value TG1 (NO in step S215), the process of the controller 8 returns to step S203. If the controller 8 determines that the toner remaining amount X is equal to or less than the first gauge threshold value TG1 (YES in step S215), the process of the controller 8 proceeds to step S217.

Step S217: The controller 8 determines whether or not the toner transport amount Y is less than or equal to the first transport amount threshold TC1. When the controller 8 determines that the toner transport amount Y is not equal to or less than the first transport amount threshold TC1 (NO in step S217), the process of the controller 8 proceeds to step S219. If the controller 8 determines that the toner transport amount Y is equal to or less than the first transport amount threshold TC1 (YES in step S217), the process of the controller 8 proceeds to step S221.

Step S219: The controller 8 sets the flag F to zero. When the processing of step S219 ends, the processing of the control section 8 returns to step S203.

Step S221: The controller 8 determines whether or not the toner remaining amount X is equal to or less than the third gauge threshold value TG3. If the controller 8 determines that the toner remaining amount X is equal to or less than the third gauge threshold value TG3 (YES in step S221), the process of the controller 8 proceeds to step S223. If the controller 8 determines that the toner remaining amount X is not equal to or less than the third gauge threshold value TG3 (NO in step S221), the process of the controller 8 proceeds to step S225.

Step S223: The controller 8 determines that the toner container 41 is near empty. When the process of step S223 ends, the near-empty determination process of the control unit 8 ends.

Step S225: The control unit 8 determines whether the flag F is 1 or not. If the control unit 8 determines that the flag F is not 1 (NO in step S225), the processing of the control unit 8 proceeds to step S227. If the control unit 8 determines that the flag F is 1 (YES in step S225), the processing of the control unit 8 proceeds to step S229.

Step S227: The controller 8 sets the flag F to 1; When the process of step S227 is finished, the process of the control section 8 returns to step S203.

Step S229: The controller 8 determines that the toner container 41 is near empty. When the process of step S229 ends, the near-empty determination process of the control unit 8 ends.

In the near-empty determination process of steps S201 to S229, the controller 8 drives the supply motor 75 for the first drive time each time the toner sensor 49 detects empty (step S209 in FIG. 7). Based on the driving history of the transport motor 77, the control unit 8 determines the transport amount Y of the toner transported from the intermediate hopper 43 from when the toner sensor 49 detects empty until it detects empty again. Calculate (step S211). Further, the control unit 8 determines that the toner container 41 is near empty when the calculated toner transport amount Y is equal to or smaller than the first transport amount threshold value TC1 for two consecutive times (step S229 in FIG. 8). .

As the remaining amount of toner X decreases, the amount of toner discharged from the toner container 41 decreases. When the amount of discharged toner decreases, the interval at which the toner sensor 49 detects empty becomes shorter. In the first embodiment, the controller 8 makes a near-empty determination for the toner container 41 by using the decrease in the empty detection interval. Therefore, when the toner container 41 is started to be used, the toner in the toner container 41 is prevented from being aggregated without excessive toner supply. In addition, when the toner is consumed, delay in replenishment from the toner container 41 is prevented, and the remaining amount of toner X when empty is reduced. In this way, the control unit 8 makes the near-empty determination of the toner container 41 at an appropriate timing.

It is known that when the remaining amount of toner X reaches several percent, the amount of conveyed toner Y suddenly decreases. The toner conveying amount Y varies depending on the conveying capacity of the toner container 41 and the shape and capacity of the intermediate hopper 43 . Therefore, although the first transport amount threshold TC1 is not particularly limited, it is preferable to set it small so as to be outside the range of variation in the toner transport amount Y until the toner remaining amount X reaches several percent.

Further, in the near-empty determination processing of steps S201 to S229, the control unit 8 estimates the toner remaining amount X in the toner container 41 from the calculated toner transport amount Y (step S213 in FIG. 7). Further, when the estimated toner remaining amount X is equal to or less than the first gauge threshold value TG1, the controller 8 determines that the calculated toner transport amount Y becomes equal to or less than the first transport amount threshold value TC1 two consecutive times. , the toner container 41 is determined to be near empty (step S229 in FIG. 8).

The reason for setting the first gauge threshold value TG1 is to prevent erroneous determination of "near empty" even if the toner in the toner container 41 is weakly aggregated, for example, in a storage state. Especially when the toner container 41 starts to be used, it may be difficult to discharge the toner from the toner container 41 . If the toner transport amount Y is greatly reduced before the remaining toner amount X becomes equal to or less than the first gauge threshold value TG1, the controller 8 may execute a special discharge sequence from the toner container 41 . Alternatively, the control unit 8 may perform display such as asking the user to take out the toner container 41 and shake it.

Further, in the near-empty determination processing of steps S201 to S229, when the calculated toner transport amount Y is equal to or greater than the second transport amount threshold value TC2, the controller 8 drives the supply motor 75 for the first driving time. (step S205 in FIG. 7). The driving of the supply motor 75 in step S205 is executed even if the toner sensor 49 does not detect empty. As shown in FIG. 4, the second transport amount threshold TC2 is set to decrease as the remaining amount of toner X in the toner container 41 decreases around X=20%.

At the beginning of use of the toner container 41, the amount of remaining toner X is large, so the amount of discharged toner container 41 is large. Therefore, the amount of toner accumulated in the intermediate hopper 43 is large when the toner container 41 is driven for a certain period of time. Therefore, there is no need to drive the toner container 41 frequently, and the drive time may be short. Conversely, if the toner container 41 is driven frequently and for a long time, the toner is compressed in the intermediate hopper 43 and the fluidity of the toner deteriorates. Therefore, when the toner remaining amount X is large, the second transport amount threshold TC2 is set to a large value. As a result, the probability that step S203 in FIG. 7 is determined to be NO increases. As a result, control using the detection result of toner sensor 49 (from step S207) is mainly executed.

As the consumption of toner progresses and the remaining amount of toner X decreases, the discharge amount of the toner container 41 decreases. Therefore, the amount of toner stored in the intermediate hopper 43 decreases when the toner container 41 is driven for a certain period of time. When the amount of toner consumed by the developing device 33 increases while the amount of toner in the intermediate hopper 43 is reduced, the supply of toner from the toner container 41 is delayed, causing various problems such as insufficient toner in the intermediate hopper 43 . Therefore, when the toner remaining amount X is small, the second transport amount threshold TC2 is set to a small value. This increases the probability of a YES determination in step S203 of FIG. Therefore, the toner container 41 is forcibly rotated regardless of whether or not the toner sensor 49 detects the empty state (step S205). As a result, the toner remaining amount X when the toner container 41 is empty is reduced.

Further, in the near-empty determination processing of steps S201 to S229, the control unit 8 determines that the toner container 41 is near-empty when the estimated remaining toner amount X is equal to or less than the third gauge threshold value TG3 ( Step S223 in FIG. 8). The near-empty determination in step S223 is executed even if the calculated toner transport amount Y is not equal to or smaller than the first transport amount threshold value TC1 for a plurality of consecutive times.

Either the first method in which the calculated toner transport amount Y is equal to or less than the first transport amount threshold value TC1 twice consecutively, or the second method in which the estimated remaining toner amount X is equal to or less than the third gauge threshold value TG3. By determining the near-empty at , the reliability of the near-empty determination is improved. Among these methods, the first method, in which it is determined that the toner container 41 is near empty when the calculated toner transport amount Y is equal to or smaller than the first transport amount threshold value TC1 for two consecutive times, is the first method. It is suitable for the case of about 500 sheets. The second method of determining the near-empty state when the estimated remaining toner amount X is equal to or less than the third gauge threshold value TG3 is suitable when the number of remaining printed sheets by the toner container 41 is 500 or more.

FIG. 9 is a flow chart showing an example of empty determination processing of the control unit 8 . The empty determination process is executed in steps S301 to S309.

Step S301: The controller 8 determines whether or not the toner remaining amount X is equal to or less than the second gauge threshold value TG2. When the control unit 8 determines that the toner remaining amount X is not equal to or less than the second gauge threshold value TG2 (NO in step S301), the empty determination processing of the control unit 8 ends. If the controller 8 determines that the toner remaining amount X is equal to or less than the second gauge threshold value TG2 (YES in step S301), the process of the controller 8 proceeds to step S303.

Step S303: Based on the detection result of the toner sensor 49, the controller 8 determines whether the intermediate hopper 43 is empty. When the control unit 8 determines that the intermediate hopper 43 is not empty (NO in step S303), the empty determination process of the control unit 8 ends. When the control unit 8 determines that the intermediate hopper 43 is empty (YES in step S303), the processing of the control unit 8 proceeds to step S305.

Step S305: The controller 8 calls a container rotation subroutine, which will be described later, so as to rotate the toner container 41. FIG. Specifically, the controller 8 drives the supply motor 75 for the second drive time. After the process of step S305 is completed, the process of the control unit 8 proceeds to step S307.

Step S307: The controller 8 determines whether or not the toner transport amount Y is equal to or less than the third transport amount threshold TC3 and the intermediate hopper 43 is empty. If the controller 8 determines that the toner transport amount Y is not equal to or less than the third transport amount threshold value TC3 or determines that the intermediate hopper 43 is not empty (NO in step S307), the controller 8 performs empty determination processing. ends. If the controller 8 determines that the toner transport amount Y is equal to or less than the third transport amount threshold TC3 and that the intermediate hopper 43 is empty (YES in step S307), the process of the controller 8 proceeds to step S309.

Step S309: The controller 8 determines that the toner container 41 is empty. When the process of step S309 ends, the empty determination process of the control unit 8 ends.

In the empty determination process of steps S301 to S309, the control unit 8 determines that the toner container 41 is empty when the toner remaining amount X is equal to or less than the second gauge threshold value TG2. The condition is that the toner transport amount Y is equal to or less than the third transport amount threshold value TC3 even if the supply motor 75 is driven for the second driving time after the toner sensor 49 detects the empty condition, and the toner sensor 49 detects the empty state. The problem is that the detection does not go away.

FIG. 10 is a flow chart showing an example of processing of the container rotation subroutine of the control unit 8. As shown in FIG. The container rotation subroutine is executed through steps S401 to S411.

Step S401: The control unit 8 determines whether or not the empty determination process described with reference to FIG. 9 is being executed. If the control unit 8 determines that the empty determination process is being executed (YES in step S401), the process of the control unit 8 proceeds to step S409. When the control unit 8 determines that the empty determination process is not being executed (NO in step S401), the processing of the control unit 8 proceeds to step S403.

Step S403: The controller 8 determines whether or not the toner remaining amount X is equal to or less than the fourth gauge threshold value TG4. If the controller 8 determines that the toner remaining amount X is equal to or less than the fourth gauge threshold value TG4 (YES in step S403), the process of the controller 8 proceeds to step S407. If the controller 8 determines that the toner remaining amount X is not equal to or less than the fourth gauge threshold value TG4 (NO in step S403), the process of the controller 8 proceeds to step S405.

Step S405: The controller 8 sets the rotation time RT of the toner container 41 to the first rotation time RT1. The first rotation time RT1 is, for example, 3 seconds or more and less than 7 seconds. When the process of step S405 is completed, the process of the control section 8 proceeds to step S411.

Step S407: The controller 8 sets the rotation time RT of the toner container 41 to the second rotation time RT2. The second rotation time RT2 is, for example, 7 seconds or more and less than 15 seconds. When the process of step S407 is finished, the process of the control section 8 proceeds to step S411.

Step S409: The controller 8 sets the rotation time RT of the toner container 41 to the third rotation time RT3. The third rotation time RT3 is, for example, 15 seconds or longer. When the processing of step S409 ends, the processing of the control section 8 proceeds to step S411.

Step S411: The controller 8 rotates the toner container 41 by driving the supply motor 75 for the rotation time RT. When the process of step S411 ends, the process of the container rotation subroutine of the control section 8 ends.

In the processing of the container rotation subroutine of steps S401 to S411, the drive time (first drive time) of the supply motor 75 during the near-empty determination is set to the first rotation time RT1 or the second rotation time RT2. Further, the drive time (second drive time) of the supply motor 75 during the empty determination is set to the third rotation time RT3. The first drive time is set around the fourth gauge threshold value TG4 so as to become longer as the remaining amount of toner X decreases. As a result, the toner remaining amount X when the toner container 41 is empty is reduced. Also, the second drive time is set longer than the first drive time so that the toner remaining in the toner container 41 can be discharged even a little.

[Second embodiment]
Next, the image forming apparatus 1 according to the second embodiment will be described. Since the overall configuration of the image forming apparatus 1 is the same as that of FIG. 1, the description thereof is omitted. FIG. 11 is a diagram showing an example of the toner replenishing device 37 according to the second embodiment.

In the second embodiment, the toner replenishing device 37 includes the vertical conveying section 120, but does not include the intermediate hopper 43, the conveying screw 47, the conveying motor 77, the toner sensor 49, and the rotation detection mechanism 51. Different from the form.

A toner container 41 shown in FIG. 11 contains toner to be supplied to the developing device 33 . The toner container 41 has a bottle shape with a discharge port 61, and has a cylindrical body portion 41a and a neck portion 41b having a diameter smaller than that of the body portion 41a. A protrusion 63 protruding into the body portion 41a is spirally formed on the inner peripheral surface of the body portion 41a. A discharge port 61 is formed on the side surface of the neck portion 41b.

The toner container attaching/detaching portion 65 detachably supports the toner container 41 . The toner container 41 is attached/detached to/from the toner container attachment/detachment portion 65 in a lateral orientation. As shown in FIG. 1, toner containers 41 for four colors are attached to the image forming apparatus 1 .

The vertical conveying portion 120 extends vertically between the toner container attaching/detaching portion 65 and the developing device 33 . An upper end opening of the vertical conveying section 120 is connected to the toner container attaching/detaching section 65 so as to be below the neck portion 41 b of the toner container 41 . A lower end opening of the vertical conveying portion 120 is connected to the toner supply port 33 a of the developing device 33 .

The rotating mechanism 45 conveys toner from the toner container 41 to the developing device 33 . The rotation mechanism 45 has a grip portion 73 that grips the neck portion 41 b of the toner container 41 and a supply motor 75 that rotates the grip portion 73 . When the supply motor 75 rotates the grip portion 73, the toner container 41 rotates. When the toner container 41 rotates, the toner stored in the body portion 41a is conveyed toward the neck portion 41b by the spiral protrusion 63 formed on the body portion 41a. The toner drops from the discharge port 61 of the neck portion 41b to the developing device 33 when the discharge port 61 faces downward. The supply motor 75 is electrically connected to the controller 8, and is controlled by the controller 8 to rotate the toner container 41 at a constant rotational speed. The rotating mechanism 45 corresponds to an example of a "conveyor". The supply motor 75 corresponds to an example of a "motor".

Next, the controller 8 according to the second embodiment will be described. FIG. 12 is a diagram showing an example of the control unit 8. As shown in FIG.

As shown in FIG. 12 , the image forming apparatus 1 has a storage section 91 in addition to the control section 8 . The control unit 8 includes a processor such as a CPU (Central Processing Unit). The storage unit 91 includes a storage device and stores data and computer programs. The storage unit 91 includes a main storage device such as a semiconductor memory and an auxiliary storage device such as a semiconductor memory and/or a hard disk drive. The processor of the control section 8 controls each component of the image forming apparatus 1 by executing a computer program stored in the storage device of the storage section 91 .

As described above, the toner supply device 37 has the supply motor 75 . The developing device 33 also has a toner density sensor 39 . The control unit 8 has a calculation unit 201 and an estimation unit 202 . The processor of the control section 8 is electrically connected to the supply motor 75 and the toner density sensor 39 and functions as a calculation section 201 and an estimation section 202 .

The calculation unit 201 calculates the transport amount Y of the toner transported from the toner container 41 during the period from when the toner density sensor 39 detects a decrease in the toner density D until when it detects a decrease in the toner density D again, as an electrostatic latent value. It is calculated based on the image formation information, for example, the integrated data of the coverage rate.

The estimation unit 202 estimates the remaining amount (percentage) X of toner in the toner container 41 from the calculated toner transport amount Y. FIG.

The contents described with reference to FIGS. 4 and 5 are also applied to the control unit 8 according to the second embodiment. However, the toner transport amount Y is the amount of toner transported from the toner container 41 after the toner density sensor 39 detects a decrease in the toner density D until it detects a decrease in the toner density D again.

Next, the processing of the control unit 8 will be described with reference to FIGS. 13 to 15. FIG. 13 and 14 are flowcharts showing an example of the near-empty processing of the control unit 8. FIG. The near-empty process is executed through steps S201 to S229.

Step S201: The controller 8 sets the flag F to zero. Flag F is a flag for confirming whether or not a specific event has occurred multiple times in succession.

Step S203: The controller 8 determines whether or not the toner transport amount Y is greater than or equal to the second transport amount threshold TC2. When the controller 8 determines that the toner transport amount Y is equal to or greater than the second transport amount threshold TC2 (YES in step S203), the process of the controller 8 proceeds to step S205. When the controller 8 determines that the toner transport amount Y is not equal to or greater than the second transport amount threshold TC2 (NO in step S203), the process of the controller 8 proceeds to step S207a.

Step S205: The controller 8 calls the container rotation subroutine described above with reference to FIG. 10 so as to rotate the toner container 41. FIG. Specifically, the controller 8 drives the supply motor 75 for the first drive time. After the process of step S205 is completed, the process of the control unit 8 returns to step S203.

Step S207a: The controller 8 determines whether the toner density D detected by the toner density sensor 39 is equal to or less than the threshold value TD1. If the controller 8 determines that the toner density D is not equal to or lower than the threshold value TD1 (NO in step S207a), the process of the controller 8 returns to step S203. If the controller 8 determines that the toner density D is equal to or less than the threshold value TD1 (YES in step S207a), the process of the controller 8 proceeds to step S209.

Step S209: The controller 8 calls a container rotation subroutine to rotate the toner container 41. FIG. Specifically, the controller 8 drives the supply motor 75 for the first drive time. After the process of step S209 is completed, the process of the control unit 8 proceeds to step S211a.

Step S211a: The control unit 8 calculates the toner transport amount Y based on the integrated coverage data. After the process of step S211a is completed, the process of the control unit 8 proceeds to step S213.

Step S213: The controller 8 estimates the remaining amount X of toner from the amount Y of toner transported. When the process of step S213 is finished, the process of the control section 8 proceeds to step S215 in FIG.

Step S215: The controller 8 determines whether or not the toner remaining amount X is equal to or less than the first gauge threshold value TG1. If the controller 8 determines that the toner remaining amount X is not equal to or less than the first gauge threshold value TG1 (NO in step S215), the process of the controller 8 returns to step S203. If the controller 8 determines that the toner remaining amount X is equal to or less than the first gauge threshold value TG1 (YES in step S215), the process of the controller 8 proceeds to step S217.

Step S217: The controller 8 determines whether or not the toner transport amount Y is less than or equal to the first transport amount threshold TC1. When the controller 8 determines that the toner transport amount Y is not equal to or less than the first transport amount threshold TC1 (NO in step S217), the process of the controller 8 proceeds to step S219. If the controller 8 determines that the toner transport amount Y is equal to or less than the first transport amount threshold TC1 (YES in step S217), the process of the controller 8 proceeds to step S221.

Step S219: The controller 8 sets the flag F to zero. When the processing of step S219 ends, the processing of the control section 8 returns to step S203.

Step S221: The controller 8 determines whether or not the toner remaining amount X is equal to or less than the third gauge threshold value TG3. If the controller 8 determines that the toner remaining amount X is equal to or less than the third gauge threshold value TG3 (YES in step S221), the process of the controller 8 proceeds to step S223. If the controller 8 determines that the toner remaining amount X is not equal to or less than the third gauge threshold value TG3 (NO in step S221), the process of the controller 8 proceeds to step S225.

Step S223: The controller 8 determines that the toner container 41 is near empty. When the process of step S223 ends, the near-empty determination process of the control unit 8 ends.

Step S225: The control unit 8 determines whether the flag F is 1 or not. If the control unit 8 determines that the flag F is not 1 (NO in step S225), the processing of the control unit 8 proceeds to step S227. If the control unit 8 determines that the flag F is 1 (YES in step S225), the processing of the control unit 8 proceeds to step S229.

Step S227: The controller 8 sets the flag F to 1; When the process of step S227 is finished, the process of the control section 8 returns to step S203.

Step S229: The controller 8 determines that the toner container 41 is near empty. When the process of step S229 ends, the near-empty determination process of the control unit 8 ends.

In the near-empty determination processing of steps S201 to S229, the controller 8 activates the supply motor 75 each time the toner density sensor 39 detects that the toner density D in the developing device 33 has decreased below the threshold value TD1. Drive for the first drive time (step S209 in FIG. 13). In addition, the controller 8 determines the transport amount Y of the toner transported from the toner container 41 during the period from when the toner density sensor 39 detects a decrease in the density D to when it detects a decrease in the density D again. It is calculated from the image formation information (step S211a). Further, the controller 8 determines that the toner container 41 is near empty when the calculated toner transport amount Y is equal to or smaller than the first transport amount threshold value TC1 for two consecutive times (step S229 in FIG. 14). .

As the remaining amount of toner X decreases, the amount of toner discharged from the toner container 41 decreases. When the toner discharge amount decreases, the intervals at which the toner concentration sensor 39 detects the decrease in the toner concentration D become shorter. In the second embodiment, the controller 8 makes a near-empty determination for the toner container 41 by using the decrease in the interval for detecting the decrease in the toner density D. FIG. Therefore, when the toner container 41 is started to be used, the toner in the toner container 41 is prevented from being aggregated without excessive toner supply. In addition, when the toner is consumed, delay in replenishment from the toner container 41 is prevented, and the remaining amount of toner X when empty is reduced. In this way, the control unit 8 makes the near-empty determination of the toner container 41 at an appropriate timing.

It is known that when the remaining amount of toner X reaches several percent, the amount of conveyed toner Y suddenly decreases. The toner transport amount Y varies depending on the transport capability of the toner container 41 . Therefore, although the first transport amount threshold TC1 is not particularly limited, it is preferable to set it small so as to be outside the range of variation in the toner transport amount Y until the toner remaining amount X reaches several percent.

Further, in the near-empty determination process of steps S201 to S229, the control unit 8 estimates the toner remaining amount X in the toner container 41 from the calculated toner transport amount Y (step S213 in FIG. 13). Further, when the estimated toner remaining amount X is equal to or less than the first gauge threshold value TG1, the controller 8 determines that the calculated toner transport amount Y becomes equal to or less than the first transport amount threshold value TC1 two consecutive times. , the toner container 41 is determined to be near empty (step S229 in FIG. 14).

The reason for setting the first gauge threshold value TG1 is to prevent erroneous determination of "near empty" even if the toner in the toner container 41 is weakly aggregated, for example, in a storage state. Especially when the toner container 41 starts to be used, it may be difficult to discharge the toner from the toner container 41 . If the toner transport amount Y is greatly reduced before the remaining toner amount X becomes equal to or less than the first gauge threshold value TG1, the controller 8 may execute a special discharge sequence from the toner container 41 . Alternatively, the control unit 8 may perform display such as asking the user to take out the toner container 41 and shake it.

Further, in the near-empty determination processing of steps S201 to S229, when the calculated toner transport amount Y is equal to or greater than the second transport amount threshold value TC2, the controller 8 drives the supply motor 75 for the first driving time. (step S205 in FIG. 13). The driving of the supply motor 75 in step S205 is executed even if the toner concentration sensor 39 does not detect a decrease in the toner concentration D. As shown in FIG. 4, the second transport amount threshold TC2 is set to decrease as the remaining amount of toner X in the toner container 41 decreases around X=20%.

At the beginning of use of the toner container 41, the amount of remaining toner X is large, so the amount of discharged toner container 41 is large. Therefore, a large amount of toner is supplied to the developing device 33 by driving the toner container 41 for a certain period of time. Therefore, there is no need to drive the toner container 41 frequently, and the drive time may be short. Therefore, when the toner remaining amount X is large, the second transport amount threshold TC2 is set to a large value. As a result, the probability that step S203 in FIG. 13 is determined to be NO increases. As a result, control using the detection result of the toner concentration sensor 39 (from step S207a) is mainly executed.

As the consumption of toner progresses and the remaining amount of toner X decreases, the discharge amount of the toner container 41 decreases. Therefore, the amount of toner supplied to the developing device 33 decreases when the toner container 41 is driven for a certain period of time. If the amount of toner consumed by the developing device 33 increases while the amount of toner supplied to the developing device 33 is reduced, a problem arises that the toner supply from the toner container 41 is delayed. Therefore, when the toner remaining amount X is small, the second transport amount threshold TC2 is set to a small value. This increases the probability of a YES determination in step S203 of FIG. Therefore, the toner container 41 is forced to rotate regardless of whether the toner density sensor 39 detects a decrease in the toner density D (step S205 in FIG. 13). As a result, the toner remaining amount X when the toner container 41 is empty is reduced.

Further, in the near-empty determination processing of steps S201 to S229, the control unit 8 determines that the toner container 41 is near-empty when the estimated remaining toner amount X is equal to or less than the third gauge threshold value TG3 ( Step S223 in FIG. 14). The near-empty determination in step S223 is executed even if the calculated toner transport amount Y is not equal to or smaller than the first transport amount threshold value TC1 for a plurality of consecutive times.

Either the first method in which the calculated toner transport amount Y is equal to or less than the first transport amount threshold value TC1 twice consecutively, or the second method in which the estimated remaining toner amount X is equal to or less than the third gauge threshold value TG3. By determining the near-empty at , the reliability of the near-empty determination is improved. Among these methods, the first method, in which it is determined that the toner container 41 is near empty when the calculated toner transport amount Y is equal to or smaller than the first transport amount threshold value TC1 for two consecutive times, is the first method. It is suitable for the case of about 500 sheets. The second method of determining the near-empty state when the estimated remaining toner amount X is equal to or less than the third gauge threshold value TG3 is suitable when the number of remaining printed sheets by the toner container 41 is 500 or more.

FIG. 15 is a flow chart showing an example of empty determination processing of the control unit 8 . The empty determination process is executed in steps S301 to S309.

Step S301: The controller 8 determines whether or not the toner remaining amount X is equal to or less than the second gauge threshold value TG2. When the control unit 8 determines that the toner remaining amount X is not equal to or less than the second gauge threshold value TG2 (NO in step S301), the empty determination processing of the control unit 8 ends. If the controller 8 determines that the toner remaining amount X is equal to or less than the second gauge threshold value TG2 (YES in step S301), the process of the controller 8 proceeds to step S303a.

Step S303a: The controller 8 determines whether the toner density D detected by the toner density sensor 39 is equal to or less than the threshold value TD1. If the control unit 8 determines that the toner concentration D is not equal to or less than the threshold value TD1 (NO in step S303a), the empty determination process of the control unit 8 ends. If the controller 8 determines that the toner density D is equal to or less than the threshold value TD1 (YES in step S303a), the process of the controller 8 proceeds to step S305.

Step S305: The controller 8 calls a container rotation subroutine to rotate the toner container 41. FIG. Specifically, the controller 8 drives the supply motor 75 for the second drive time. When the process of step S305 is completed, the process of the control section 8 proceeds to step S307a.

Step S307a: The controller 8 determines whether the toner transport amount Y is equal to or less than the third transport amount threshold TC3 and the toner density D is equal to or less than the threshold TD1. If the control unit 8 determines that the toner transport amount Y is not equal to or less than the third transport amount threshold value TC3 or that the toner density D is not equal to or less than the threshold value TD1 (NO in step S307a), the control unit 8 is empty. Judgment processing ends. When the controller 8 determines that the toner transport amount Y is equal to or less than the third transport amount threshold TC3 and the toner density D is equal to or less than the threshold TD1 (YES in step S307a), the process of the controller 8 proceeds to step S309. .

Step S309: The controller 8 determines that the toner container 41 is empty. When the process of step S309 ends, the empty determination process of the control unit 8 ends.

In the empty determination process of steps S301 to S309, the control unit 8 determines that the toner container 41 is empty when the toner remaining amount X is equal to or less than the second gauge threshold value TG2. The condition is that the toner transport amount Y is equal to or less than the third transport amount threshold value TC3 even if the supply motor 75 is driven for the second drive time after the toner density sensor 39 detects a decrease in the density D, and the toner density The problem is that the detection of the decrease in the density D by the sensor 39 is not resolved.

Further, as described with reference to FIG. 10, in the processing of the container rotation subroutine of the control unit 8 (steps S401 to S411 in FIG. 10), the drive time (first drive time) of the supply motor 75 during the near-empty determination time) is referred to as a first rotation time RT1 or a second rotation time RT2. Further, the drive time (second drive time) of the supply motor 75 during the empty determination is set to the third rotation time RT3. The first drive time is set around the fourth gauge threshold value TG4 so as to become longer as the remaining amount of toner X decreases. As a result, the toner remaining amount X when the toner container 41 is empty is reduced. Also, the second drive time is set longer than the first drive time so that the toner remaining in the toner container 41 can be discharged even a little.

Since the above description of each embodiment describes a preferred embodiment of the present invention, various technically preferable limitations may be attached, but the technical scope of the present invention is particularly limited to the present invention. is not limited to these embodiments unless otherwise specified. That is, the constituent elements in the above embodiments can be appropriately replaced with existing constituent elements and the like, and various variations including combinations with other existing constituent elements are possible. The above description of the embodiment is not intended to limit the scope of the invention described in the claims.

(1) In the first embodiment, the rotation detection mechanism 51 has the pulse plate 81 and the transmissive photosensor 83 . The control unit 8 counts the pulse waveform output from the transmissive photosensor 83 to calculate the rotation speed of the transport motor 77 . Alternatively, a stepping motor may be employed as the transfer motor 77 and the stepping motor may be pulse-controlled. Further, the drive time of the transport motor 77 may be integrated.

(2) In the first embodiment, the controller 8 controls the supply motor 75 and the transport motor 77 independently of each other. However, a configuration in which the transport motor 77 always rotates during printing, or a configuration in which the supply motor 75 and the transport motor 77 rotate in conjunction with each other is also conceivable. In these assumed configurations, the toner container 41 and the intermediate hopper 43 constitute one toner container, and the supply motor 75 and the transport motor 77 constitute one toner transport section. Then, it is possible to apply the near-empty determination using the toner concentration sensor 39 as described in the second embodiment.

(3) In the second embodiment, the calculation of the toner transport amount Y by the control unit 8 is based on the cumulative coverage data. Alternatively, the calculation of the toner transport amount Y by the controller 8 may be based on the drive history of the rotating mechanism 45 .

(4) In the first and second embodiments, the number of toner containers 41 rotated by one supply motor 75 was one. Alternatively, the number of toner containers 41 rotated by one supply motor 75 may be two or more. The number of supply motors 75 can be reduced, and the cost can be reduced. The rotation time RT of the supply motor 75 is determined by each toner supply device 37, and each toner container 41 is rotated according to the longest rotation time RT. As a result, it is possible to avoid a situation in which the amount of toner supplied from the toner container 41 to the intermediate hopper 43 or the amount of toner supplied from the toner container 41 to the developing device 33 is insufficient.

INDUSTRIAL APPLICABILITY The present invention can be used in the field of image forming apparatuses.

1 image forming device 8 control section 33 developing device 37 toner supply device 39 toner density sensor (second detection section, detection section)
41 toner container 43 intermediate hopper (intermediate conveying path)
45 rotation mechanism (first transport unit, transport unit)
47 transport screw (second transport unit)
49 toner sensor (first detector)
51 rotation detection mechanism 75 supply motor (first motor, motor)
77 transport motor (second transport section, second motor)
TC1 First transport amount threshold TC2 Second transport amount threshold TC3 Third transport amount threshold TG1 First gauge threshold TG2 Second gauge threshold TG3 Third gauge threshold TG4 Fourth gauge threshold X Remaining toner amount Y Toner transport amount

Claims (7)

a developing device that develops the electrostatic latent image into a toner image;
a toner container containing toner to be replenished to the developing device;
a conveying unit that conveys toner from the toner container to the developing device;
a detection unit that detects the concentration of toner in the developing device;
A control unit that controls the transport unit,
The control unit
driving the conveying unit for a first driving time each time the detecting unit detects that the concentration of toner in the developing device has decreased below a predetermined value;
calculating, based on the electrostatic latent image formation information, a transport amount of toner transported from the toner container during a period from when the detection unit detects the density decrease until when the density decrease is detected again;
estimating the remaining amount of toner in the toner container from the calculated amount of conveyed toner;
When the estimated remaining amount of toner is equal to or less than the first gauge threshold and the calculated toner transport amount becomes equal to or less than the first transport amount threshold for a plurality of consecutive times, the toner container is near empty. An image forming device that determines that The first transport amount threshold is smaller than a value F(0) indicating a result of extrapolating the regression curve Y=F(X) to X=0%,
The regression curve Y=F(X) is defined by the remaining amount X of the toner in the toner container and the toner container after the detection unit detects the decrease in density until it detects the decrease in density again. 2. The image forming apparatus according to claim 1, which represents the relationship between the amount Y of the toner conveyed from . 3. The image forming apparatus according to claim 1, wherein said conveying section has a motor for rotating said toner container so as to convey toner from said toner container to said developing device. When the calculated toner transport amount is equal to or greater than a second transport amount threshold, the control unit drives the transport unit for the first drive time even if the detection unit does not detect a decrease in density. death,
The image forming apparatus according to any one of claims 1 to 3, wherein the second transport amount threshold is set to decrease as the amount of toner remaining in the toner container decreases. The image forming apparatus according to any one of claims 1 to 4, wherein the first drive time is set to increase as the remaining amount of toner in the toner container decreases. The control unit
estimating the remaining amount of toner in the toner container from the calculated amount of conveyed toner;
When the estimated remaining amount of toner is equal to or less than the second gauge threshold, even if the conveying unit is driven for the second drive time after the detection unit detects a decrease in density, the toner is not conveyed from the toner container. determining that the toner container is empty when the conveyed amount of toner is less than or equal to a third conveyed amount threshold and the detection of the decrease in density by the detection unit is not resolved;
6. The image forming apparatus according to claim 1, wherein said second driving time is longer than said first driving time. The control unit
estimating the amount of toner in the toner container from the calculated toner transport amount;
When the estimated remaining amount of toner is equal to or less than the third gauge threshold value, the toner container may continue to be discharged even if the calculated toner transport amount is not equal to or less than the first transport amount threshold value for a plurality of consecutive times. 7. The image forming apparatus according to claim 1, wherein the image forming apparatus determines that it is near empty.

Images