Image forming apparatus

Abstract

Improve the toner replenishment process. [Solution] The rotary tiller is a rotary tiller to which a toner cartridge containing toner can be attached and detached, and comprises a developing roller and a storage section for storing the developer supplied from the toner cartridge. The state of the storage section when the remaining amount of toner in the storage section exceeds a first threshold is the first state. The state of the storage section when the remaining amount of toner in the storage section is less than the first threshold is the second state. The time the rotary tiller assumes the replenishment posture in the replenishment mode performed when the storage section is in the first state is the first time. The time the rotary tiller assumes the replenishment posture in the replenishment mode performed when the storage section is in the second state is the second time. The second time is longer than the first time.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus. Background Art

[0002] The image forming apparatus described in Patent Document 1 interrupts a monochrome print job and performs toner supply when the amount of black toner in a developing chamber is equal to or less than a predetermined amount after the start of the monochrome print job. Prior Art Documents Patent Documents

[0003] Patent Document 1 Japanese Unexamined Patent Application Publication No. 2009-008794 Summary of the Invention Problem to be Solved by the Invention

[0004] According to Patent Document 1, the supply operation is not changed depending on the remaining amount of toner in the developing chamber. Therefore, the supply amount has not been adjusted depending on the remaining amount of toner in the developing chamber. Means for Solving the Problem

[0005] The present invention provides, for example, a rotary to which a toner cartridge containing toner can be attached and detached, the rotary including a developing roller and an accommodating portion that accommodates developer supplied from the toner cartridge; a control unit that controls rotation of the rotary; wherein the rotary can assume a supply posture in which toner is supplied from the toner cartridge to the accommodating portion, the control unit executes a supply mode in which the rotary is rotated to assume the supply posture, a state of the accommodating portion when the remaining amount of toner in the accommodating portion exceeds a first threshold is defined as a first state, The state of the storage unit when the remaining amount of toner in the storage unit is less than the first threshold is defined as the second state. In the replenishment mode performed when the housing is in the first state, the time during which the rotary assumes the replenishment posture is defined as the first time. In the replenishment mode performed when the housing is in the second state, the time during which the rotary assumes the replenishment posture is defined as the second time. The control unit executes the replenishment mode such that the second time is longer than the first time. The present invention provides an image forming apparatus characterized by the following features. [Effects of the Invention]

[0006] According to the present invention, the toner replenishment operation is improved. [Brief explanation of the drawing]

[0007] [Figure 1] Diagram illustrating an image forming apparatus. [Figure 2] Diagram showing developing position and standby position. [Figure 3] Diagram showing development and replenishment positions. [Figure 4] Diagram illustrating the developing assembly. [Figure 5] Diagram explaining the controller [Figure 6] Diagram explaining the predetermined quantity [Figure 7] Diagram explaining how supply levels are determined. [Figure 8] Flowchart showing the control method [Figure 9] Flowchart showing the control method [Figure 10] Diagram explaining the predetermined quantity [Figure 11] Diagram explaining how supply levels are determined. [Modes for carrying out the invention]

[0008] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. The following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of the plurality of features are essential to the invention, and the plurality of features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and duplicate descriptions are omitted.

[0009] 1. First Embodiment As shown in FIG. 1, the image forming apparatus 1 is a printer adopting a rotary developing system. In each of the following drawings, it is assumed that the image forming apparatus 1 is disposed parallel to a horizontal plane. The X direction and the Y direction are each parallel to the horizontal plane. The Z direction is parallel to the vertical direction. The Y direction is parallel to the rotation axis 90C of the rotary main body 90. The X direction, the Y direction, and the Z direction are orthogonal to each other.

[0010] 1-1. Image Forming Apparatus The image forming apparatus 1 is a laser beam printer that forms an image on a sheet S by an electrophotographic method. The image forming apparatus 1 includes four developing units 50y, 50m, 50c, and 50k each having a different color. The four developing units 50y, 50m, 50c, and 50k are held by the rotary main body 90. In the present specification, ymck is an abbreviation for yellow, magenta, cyan, and black, which are toner colors, respectively. When matters common to ymck are described, the characters ymck may be omitted from the reference numerals. Examples of the sheet S, which is a recording material (recording medium), include paper such as plain paper and cardboard, plastic film, cloth, sheet materials subjected to surface treatment such as coated paper, and specially shaped sheet materials such as envelopes and index paper.

[0011] The image forming apparatus 1 includes an image forming apparatus main body (hereinafter referred to as apparatus main body 1A), and toner cartridges 70y, 70m, 70c, and 70k as toner containers detachably attachable to the apparatus main body 1A. The apparatus main body 1A is a portion of the image forming apparatus 1 excluding the toner cartridges 70y, 70m, 70c, and 70k.

[0012] The apparatus main body 1A includes an electrophotographic photosensitive member having a drum shape (cylindrical shape) (hereinafter, photosensitive drum 2) as an image bearing member that bears an electrostatic latent image. Around the photosensitive drum 2, a charging roller 3, an exposure device (scanner 4), and a cleaning unit 6 are arranged.

[0013] The charging roller 3 is an example of a charging means that uniformly charges the surface of the photosensitive drum 2. The scanner 4 is an example of an exposing means that forms an electrostatic latent image by irradiating the photosensitive drum 2 with laser light corresponding to image information. The cleaning unit 6 is an example of a cleaning means that removes toner remaining on the surface of the photosensitive drum 2.

[0014] The rotary main body 90 develops the electrostatic latent image to form a toner image by supplying toner to the photosensitive drum 2. The primary transfer roller 11 transfers the toner image from the photosensitive drum 2 to the intermediate transfer unit 10 (primary transfer).

[0015] The intermediate transfer unit 10 includes an intermediate transfer belt 10a, a drive roller 10b, a tension roller 10c, a cleaning device 13, and the primary transfer roller 11. The intermediate transfer belt 10a is an example of an intermediate transfer member that bears an image transferred from the photosensitive drum 2, conveys the image, and transfers the image onto a sheet S. The intermediate transfer belt 10a is stretched around the drive roller 10b and the tension roller 10c. The drive roller 10b is a drive member that rotationally drives the intermediate transfer belt 10a.

[0016] The main body of the device 1A includes a sheet storage section 35, a pickup roller 36, a feed roller 38, a separation roller 37, a transport roller pair 39, a secondary transfer roller 12, a fixing device 40, and an intermediate transfer unit 10. The sheet storage section 35 can accommodate multiple sheets S. The pickup roller 36 is an example of a feeding means for feeding sheets S from the sheet storage section 35 to the transport path. The feed roller 38 and separation roller 37 are examples of a separation transport unit that separates and transports one sheet S from multiple sheets S. The secondary transfer roller 12 is an example of a transfer means for transferring an image (toner image) from the intermediate transfer belt 10a to the sheet S.

[0017] The fixing device 40 supplies heat and pressure to the toner image and the sheet S. This fixes the toner image onto the sheet S. The sheet S is then discharged to the outside of the image forming apparatus 1.

[0018] 1-2. Rotary body The rotary body 90 is a rotating body. The rotary body 90 has trays 80y, 80m, 80c, and 80k. Toner cartridges 70y, 70m, 70c, and 70k are removablely mounted in trays 80y, 80m, 80c, and 80k, respectively. Trays 80y, 80m, 80c, and 80k are support members that support the toner cartridges 70y, 70m, 70c, and 70k, respectively.

[0019] The 50y, 50m, 50c, and 50k developing units are supplied with yellow toner, magenta toner, cyan toner, and black toner, respectively, from the 70y, 70m, 70c, and 70k toner cartridges. The 50y, 50m, 50c, and 50k developing units then use the yellow toner, magenta toner, cyan toner, and black toner, respectively, to form a toner image.

[0020] Each developing unit 50y, 50m, 50c, and 50k has developing rollers 51y, 51m, 51c, and 51k, and supply rollers 52y, 52m, 52c, and 52k, respectively. The supply rollers 52y, 52m, 52c, and 52k are supply members that supply toner contained in the developing units 50y, 50m, 50c, and 50k to the developing rollers 51y, 51m, 51c, and 51k, respectively. Each developing roller 51y, 51m, 51c, and 51k is a developer carrier that carries toner, rotates, and supplies it to the photosensitive drum 2.

[0021] 1-2. Rotation position of the rotary body 1-2-1. Development posture Figure 2(A) shows the developing position of the rotary unit 90 (yellow developing position). As the rotary unit 90 rotates, one of the multiple developing units 50y, 50m, 50c, and 50k faces the photosensitive drum 2. In this example, the yellow developing unit 50y faces the photosensitive drum 2. That is, the yellow developing unit 50y is positioned in the developing position. When the rotary unit 90 rotates clockwise by about 90 degrees, the magenta developing unit 50m is positioned in the developing position (magenta developing position). When the rotary unit 90 rotates clockwise by another 90 degrees, the cyan developing unit 50c is positioned in the developing position (cyan developing position). When the rotary unit 90 rotates clockwise by another 90 degrees, the black developing unit 50k is positioned in the developing position (black developing position).

[0022] 1-2-2. Exchange posture Figure 2(B) shows the replacement position (black replacement position). The toner cartridges 70y to 70k are detachably held in trays 80y to 80k, respectively. The trays 80y to 80k are slidably supported by the rotary body 90. Therefore, the toner cartridges 70y to 70k slide together with the trays 80y to 80k. According to Figure 2(B), the black toner cartridge 70k is positioned for replacement. The exterior of the device body 1A has an openable and closable cover 14. When the cover 14 is opened, the tray 80k and toner cartridge 70k, which are in the replacement position, slide in the -X direction. This exposes the toner cartridge 70k to the outside of the image forming apparatus 1, allowing the user to replace the toner cartridge 70k.

[0023] When the rotary unit 90 rotates approximately 90 degrees clockwise, the yellow toner cartridge 70y is positioned for replacement (yellow replacement position). When the rotary unit 90 rotates another 90 degrees clockwise, the magenta toner cartridge 70m is positioned for replacement (magenta replacement position). When the rotary unit 90 rotates another 90 degrees clockwise, the cyan toner cartridge 70c is positioned for replacement (cyan replacement position).

[0024] When the rotary body 90 assumes the replacement position, the oscillating shaft 91 oscillates the rotary body 90, separating it from the photosensitive drum 2. Once the toner cartridge 70 replacement is complete, the oscillating shaft 91 oscillates the rotary body 90, bringing it into contact with the photosensitive drum 2. In other words, when the rotary body 90 assumes the developing position, it is in contact with the photosensitive drum 2.

[0025] 1-2-3. Standby position Figure 3(A) shows an example of a standby posture (standby position). By rotating around the rotation axis 90C, the rotary body 90 can assume a standby posture in which none of the developing rollers 51y, 51m, 51c, and 51k are facing the photosensitive drum 2. The standby posture is the position in which the photosensitive drum 2 is positioned between the developing rollers 51c and 51k. In the standby posture, the developing rollers 51 and the photosensitive drum 2 are separated. The rotary body 90 maintains the standby posture while waiting for image formation to be performed.

[0026] 1-2-4. Supply posture Figure 3(B) shows the rotary body 90 in the replenishment position (black replenishment position). In this example, the black toner contained in the toner cartridge 70k is pulled down by gravity and replenished from the toner cartridge 70k to the developer unit 50k. In other words, as the rotary body 90 rotates, the developer unit 50 and the toner cartridge 70 pass through a predetermined range of rotation. This replenishes toner from the container of the toner cartridge 70 to the container of the developer unit 50. The predetermined range of rotation includes the replenishment position shown in Figure 3(B).

[0027] When the rotary unit 90 rotates approximately 90 degrees clockwise, the yellow toner cartridge 70y is positioned in the replenishment position (yellow replenishment position). When the rotary unit 90 rotates another 90 degrees clockwise, the magenta toner cartridge 70m is positioned in the replenishment position (magenta replenishment position). When the rotary unit 90 rotates another 90 degrees clockwise, the cyan toner cartridge 70c is positioned in the replenishment position (cyan replenishment position). Therefore, one full rotation of the rotary unit 90 replenishes toner to each of the developing units 50y, 50m, 50c, and 50k.

[0028] 1-3. Details of the toner cartridge and developer unit As shown in Figure 4, the developing assembly 400 includes a developing unit 50 and a toner cartridge 70. The toner cartridge 70 has a toner frame 71. The toner frame 71 comprises a toner container 71a for containing toner and an outlet opening 71b communicating with the toner container 71a.

[0029] The developing unit 50 has a developing frame (storage frame) 53. The developing frame 53 includes a toner supply chamber 53a and a receiving opening 53b that communicates with the toner supply chamber 53a. The toner supply chamber 53a is a container that houses the toner supplied from the toner cartridge 70. The developing unit 50 has a developing roller 51 and a supply roller 52. For the sake of simplicity, these components are omitted in Figure 4.

[0030] The toner cartridge 70 is slidable between an installed position (supplyable position) and a retracted position (replacement position) relative to the developing frame 53. When the toner cartridge 70 is in the installed position, the discharge opening 71b faces the receiving opening 53b. In other words, the toner container 71a of the toner cartridge 70 and the toner supply chamber 53a of the developing unit 50 are in communication via the discharge opening 71b and the receiving opening 53b. As the rotary body 90 rotates, at least a portion of the receiving opening 53b may be positioned below (-Z side) at least a portion of the discharge opening 71b. At this time, toner is supplied from the toner cartridge 70 to the developing unit 50 via the discharge opening 71b and the receiving opening 53b.

[0031] As shown in Figure 4, the replenishment posture includes all postures in which the direction from the first opening, the discharge opening 71b, to the second opening, the receiving opening 53b, includes a downward component G in the vertical direction. Thus, the force applied to the toner contained in the toner cartridge 70 is a vector and is composed of two or more components. It is sufficient that these two or more components include a component oriented in the vertical direction. The operation in which the rotary body 90 assumes the replenishment posture and toner is replenished from the toner cartridge 70 to the developing unit 50 may be called the replenishment operation or replenishment mode. There is a replenishment posture for each of the four colors of toner. For example, Figure 3(B) shows the replenishment posture for black. Since the discharge opening 71b for black is located below the toner cartridge 70k, gravity efficiently pushes the black toner to the developing unit 50k. In other words, the toner contained in the toner container 71a is discharged from the discharge opening 71b, and the toner discharged from the discharge opening 71b is received into the toner supply chamber 53a through the receiving opening 53b. The toner contained in the toner supply chamber 53a is supplied to the developing roller 51. Through this supply path, the toner contained in the toner container 71a is supplied to the developing roller 51.

[0032] 1-4. Controller Figure 5 shows the controller of the image forming apparatus 1 that performs image forming operations. The CPU 501 is a processor that controls the image forming apparatus 1 by executing a control program stored in the ROM area of ​​the memory 502. The CPU 501 may include one or more processors or one or more processor cores. ROM is an abbreviation for read-only memory. The memory 502 includes a random access memory (RAM) area that functions as a work area. Note that the memory 502 is not limited to semiconductor memory elements and may include a hard disk drive (HDD), etc.

[0033] The controller 500 controls, for example, motors M1, M2, M3, and M4. Motor M1 is a drive source that rotates the rotary body 90 around the rotation axis 90C. Motor M2 slides the tray 80 that is in the replacement position among the trays 80y, 80m, 80c, and 80k via a drive force transmission device (e.g., gears, shafts, belts). Motor M3 drives components other than those driven by motors M1 and M2. For example, motor M3 drives the photosensitive drum 2, developing units 50y, 50m, 50c, 50k, pickup roller 36, feed roller 38, transport roller pair 39, secondary transfer roller 12, drive roller 10b, and fixing device 40. Motor M4 rotates the oscillating shaft 91. Note that the components driven by motors M1, M2, M3, and M4 can be changed as appropriate. Any two or more of motors M1, M2, M3, and M4 may be combined into a single motor. On the other hand, motors other than M1, M2, M3, and M4 and drive sources (e.g., solenoids) may be added.

[0034] The CPU 501 implements several functions by executing a control program. One or more, or all, of these functions may be implemented by other hardware circuits (e.g., ASIC, FPGA). ASIC stands for Application-Specific Integrated Circuit. FPGA stands for Field-Programmable Gate Array.

[0035] The acquisition unit 511 acquires the remaining toner amount Ta in each of the developing units 50y, 50m, 50c, and 50k, and the remaining toner amount Tb in each of the toner cartridges 70y, 70m, 70c, and 70k. The acquisition unit 511 has a detection unit 512 and a calculation unit 513. The detection unit 512 detects the remaining toner amount Ta of the developing units 50y, 50m, 50c, and 50k using sensors 503y, 503m, 503c, and 503k. The sensors 503y, 503m, 503c, and 503k each have, for example, a light-emitting element that emits light into windows provided on two opposing walls of the developing units 50y, 50m, 50c, and 50k, and a light-receiving element that receives the light through the windows. One window is called the light-ingress window, and the other window is called the light-emission window. The detection unit 512 detects the remaining toner amount Ta based on the intensity of light received by the light-receiving element. Here, the window is positioned according to a predetermined amount T1 used as a threshold for the remaining toner amount Ta. If the remaining toner amount Ta is greater than the predetermined amount T1, the light from the light-emitting element toward the light-receiving element is blocked by the toner. If the remaining toner amount Ta is less than the predetermined amount T1, the light from the light-emitting element toward the light-receiving element is not blocked by the toner. Therefore, the detection unit 512 can detect whether the remaining toner amount Ta exceeds the predetermined amount T1 or not. The window, light-emitting element, and light-receiving element may be positioned at a location corresponding to a predetermined amount T2 that is greater than the predetermined amount T1. In this case, the detection unit 512 can also detect whether the remaining toner amount Ta exceeds the predetermined amount T2 or not.

[0036] In this way, the CPU 501 detects or determines whether the remaining toner amount Ta exceeds a predetermined amount T1. The CPU 501 also detects or determines whether the remaining toner amount Ta exceeds a predetermined amount T2. However, this is just one example. The replenishment operation should be changed according to the remaining toner amount Ta. For example, a predetermined replenishment operation is performed when the remaining toner amount Ta exceeds a predetermined amount T2. If the remaining toner amount Ta is less than or equal to the predetermined amount T2 but exceeds the predetermined amount T1, another predetermined replenishment operation is performed. Similarly, when the remaining toner amount Ta falls below a predetermined amount T1, yet another predetermined replenishment operation is performed.

[0037] The detection unit 512 detects the remaining toner amount Tb of toner cartridges 70y, 70m, 70c, and 70k using sensors 504y, 504m, 504c, and 504k. Sensors 504y, 5034, 504c, and 504k each have, for example, a light-emitting element that emits light into windows provided on two opposing walls of toner cartridges 70y, 70m, 70c, and 70k, and a light-receiving element that receives the light through the windows. The detection unit 512 detects the remaining toner amount Tb based on the intensity of the light received by the light-receiving element. Here, the windows are provided according to a predetermined amount T3 used as a threshold for the remaining toner amount Tb. If the remaining toner amount Tb is greater than the predetermined amount T3, the light from the light-emitting element toward the light-receiving element is blocked by the toner. If the remaining toner amount Tb is less than the predetermined amount T3, the light from the light-emitting element toward the light-receiving element is not blocked by the toner. Therefore, the detection unit 512 can detect whether the remaining toner amount Tb exceeds a predetermined amount T3 or not. A window, light-emitting element, and light-receiving element may be positioned at a location corresponding to a predetermined amount T4 that is greater than the predetermined amount T3. In this case, the detection unit 512 can also detect whether the remaining toner amount Tb exceeds a predetermined amount T4 or not.

[0038] In this way, the CPU 501 detects or determines whether the remaining toner amount Tb exceeds a predetermined amount T3. The CPU 501 also detects or determines whether the remaining toner amount Tb exceeds a predetermined amount T4. However, this is just one example. The replenishment operation should be changed according to the remaining toner amount Tb. For example, a predetermined replenishment operation is performed when the remaining toner amount Tb exceeds a predetermined amount T4. If the remaining toner amount Tb is less than or equal to the predetermined amount T4 but exceeds the predetermined amount T3, another predetermined replenishment operation is performed. Similarly, when the remaining toner amount Tb falls to or below a predetermined amount T3, yet another predetermined replenishment operation is performed.

[0039] The arithmetic unit 513 calculates the remaining toner amount Ta of the developing units 50y, 50m, 50c, and 50k using counters 505y, 505m, 505c, and 505k. The counters 505y, 505m, 505c, and 505k count the amount of toner consumed, which is obtained by analyzing the image data that forms the basis of the image. The counters 505y, 505m, 505c, and 505k accumulate the consumption amount. Memory 502 or memories 507k, 507m, 507c, and 507k store the initial value (toner amount when full) of the remaining toner amount Ta of the developing units 50y, 50m, 50c, and 50k. Memories 507k, 507m, 507c, and 507k are memories held in the toner cartridges 70y, 70m, 70c, and 70k. The calculation unit 513 subtracts the toner consumption amounts indicated by counters 505y, 505m, 505c, and 505k from their respective initial values. This gives the remaining toner amounts Ta for the developing units 50y, 50m, 50c, and 50k.

[0040] The calculation unit 513 calculates the remaining toner amount Tb of toner cartridges 70y, 70m, 70c, and 70k using counters 506y, 506m, 506c, and 506k. Counters 506y, 506m, 506c, and 506k count the amount of toner consumed, which is obtained by analyzing the image data that forms the basis of the image. Counters 506y, 506m, 506c, and 506k accumulate the consumption. Memory 502 or memories 507k, 507m, 507c, and 507k store the initial value (amount of toner when full) of the remaining toner amount Tb of toner cartridges 70y, 70m, 70c, and 70k. The calculation unit 513 subtracts the toner consumption indicated by counters 506y, 506m, 506c, and 506k from their respective initial values. This allows you to obtain the remaining toner level Tb for toner cartridges 70y, 70m, 70c, and 70k.

[0041] Counters 505 and 506 count toner consumption, but may also be configured to count the remaining toner levels Ta and Tb. In this case, counters 505 and 506 subtract the amount of toner consumed from the remaining toner level each time toner is consumed from an initial value.

[0042] Counter 505 counts the remaining toner amount Ta in the developing unit 50. If the remaining toner amount Tb in the toner cartridge 70 is sufficiently high, counter 505 is reset to its initial value each time a replenishment operation is performed. Counter 506 is reset to its initial value each time the toner cartridge 70 is replaced with a new one.

[0043] In the first embodiment, sensor 503 is used, and sensors 504 and counters 505 and 506 are optional. In other words, counter 505 may be used instead of sensor 503. In the second embodiment, sensors 503 and counter 506 are used. In this case, sensor 504 may be used instead of counter 506. Furthermore, counter 505 may be used instead of sensor 503.

[0044] The level determination unit 514 determines the replenishment level using at least one of the toner levels: the toner level Ta of the developing unit 50 and the toner level Tb of the toner cartridge 70. For example, the replenishment level is determined such that the lower the toner level Ta, the greater the amount of toner replenished from the toner cartridge 70 to the developing unit 50. To increase the amount of toner replenished, a more enhanced replenishment operation is performed. For example, the replenishment operation at replenishment level Lv2 is more enhanced than the replenishment operation at replenishment level Lv1. The replenishment operation at replenishment level Lv3 is more enhanced than the replenishment operation at replenishment level Lv2. In other words, the replenishment operation at replenishment level Lvi+1 is more enhanced than the replenishment operation at replenishment level Lvi. i is a positive integer greater than or equal to 1. By enhancing the replenishment operation, the time for which the replenishment posture is maintained increases, or the reliability of toner replenishment increases.

[0045] The event monitoring unit 515 monitors for the occurrence of events that trigger replenishment. These events include, for example, the completion of image formation or error events that interrupt image formation (e.g., jamming of sheet S).

[0046] The position management unit 516 detects and manages the rotational position (rotational phase) of the rotary body 90. For example, an encoder is attached to the rotation axis 90C of the rotary body 90. The position management unit 516 determines the rotational position of the rotary body 90 based on the position signal output from the encoder. The position management unit 516 may also detect the home position of the rotary body 90 using a home position sensor that detects a notch or magnet provided at a specific position on the circumferential surface of the rotary body 90. In this case, the position management unit 516 counts the number of drive pulses supplied to the motor M1 using a counter that is reset each time the home position is detected. The position management unit 516 may also determine the rotational position of the rotary body 90 based on the count value of the counter. The counter of the position management unit 516 is reset to zero each time the rotary body 90 rotates once (360 degrees). As a result, the count value of the counter will always indicate the absolute rotational position.

[0047] The replenishment control unit 517 performs a replenishment operation to supply the developing unit 50 with a replenishment amount corresponding to the remaining toner (or replenishment level). Under the same toner level conditions, the amount of toner supplied changes depending on the replenishment level. For example, under the same toner level conditions, the amount of toner supplied by the replenishment operation at replenishment level Lv2 is greater than the amount of toner supplied by the replenishment operation at replenishment level Lv1. Under the same toner level conditions, the amount of toner supplied by the replenishment operation at replenishment level Lv3 is greater than the amount of toner supplied by the replenishment operation at replenishment level Lv2. The replenishment control unit 517 may repeat the replenishment operation a number of times corresponding to the remaining toner (or replenishment level). The replenishment control unit 517 may rotate the rotary body 90 a number of times corresponding to the remaining toner (or replenishment level). In other words, the number of rotations is variable (adjusted, selected, or determined) according to the remaining toner. The replenishment control unit 517 may rotate the rotary body 90 at a rotation speed corresponding to the remaining toner (or replenishment level). For example, the replenishment control unit 517 may temporarily reduce the rotation speed of the developing unit 50 to be replenished when it is in the replenishment position, below the normal rotation speed. The amount of reduction in rotation speed may be determined according to the remaining toner. Increasing the amount of reduction in rotation speed may increase the time that the replenishment position is maintained. The replenishment control unit 517 may stop the rotary body 90 for a predetermined stop period when the developing unit 50 to be replenished is in the replenishment position. The stop period is the state in which the rotation of the rotary body 90 is stopped. The replenishment control unit 517 may increase the stop period as the remaining toner decreases. The replenishment control unit 517 may measure the stop period using a timer 509 and restart the rotation of the rotary body 90 when the stop period has expired. By stopping the rotary body 90 for a predetermined stop period, the replenishment position is maintained for the predetermined stop period.

[0048] The replenishment control unit 517 refers to a table (data) stored in the ROM area of ​​the memory 502 to determine the amount of replenishment according to the remaining toner level. In this case, the table is determined in advance by experiment or simulation and written to the ROM area.

[0049] Furthermore, when the same replenishment operation is performed, the amount of toner replenished tends to be greater when the toner level Tb in the toner cartridge 70 is high. Therefore, as described later, the replenishment control unit 517 determines the number of times the replenishment operation is performed (e.g., the number of rotations of the rotary body 90) based on the toner level Tb.

[0050] When the toner level Tb of toner cartridge 70 approaches zero, the CPU 501 displays a message on the display device 508 prompting the user to replace toner cartridge 70.

[0051] 1-5. Examples of predetermined quantities Figure 6 illustrates predetermined amounts T1 and T2. In Figure 6, the developing unit 50k is described as a representative of the developing units 50y, 50m, 50c, and 50k, but the predetermined amounts T1 and T2 for the developing units 50y, 50m, and 50c are similar. In this example, the rotary body 90 is in the black developing position, so the developing roller 51k of the developing unit 50k is in contact with the photosensitive drum 2. In other words, in the developing position, the developing roller 51k can come into contact with the photosensitive drum 2. The remaining toner amount Ta of the developing unit 50k is obtained in the black developing position. Here, predetermined amounts T1 and T2 are predetermined to correspond to the position of the upper surface (interface) of the toner contained in the developing unit 50k. In particular, predetermined amount T1 is set to a slightly larger amount than the amount of toner that would result in insufficient toner supply and cause image defects. If the supply roller 52k is exposed from the toner interface, smudging will occur in solid images. Therefore, the predetermined amount T1 is the sum of the minimum amount of toner required so that the supply roller 52k is not exposed from the toner interface, and the margin. The margin is, for example, the amount of toner required to form a solid image across the entire surface of a single sheet.

[0052] The predetermined amount T2 is set to be slightly less than, for example, the effective toner upper limit Tmax of the developing unit 50. The toner upper limit Tmax is the amount of toner remaining beyond which it becomes difficult to supply toner to the developing unit 50. As shown in Figure 6, the predetermined amount T2 is defined as the amount of toner remaining at which the lower end of the receiving opening 53b in the developing position becomes the toner interface. If the upper surface of the toner is at a position higher than the lower end of the receiving opening 53b in the developing position, the toner supply path may become narrower. Toner may also flow back from the developing unit 50 to the toner cartridge 70. As a result, the amount of toner supplied will decrease significantly. The predetermined amount T2 is determined by subtracting a margin from the amount of toner remaining at which the toner interface exists at the lower end of the receiving opening 53b in the developing position. Here, the margin is the minimum amount of toner supplied from the toner cartridge 70 to the developing unit 50 when the rotary body 90 rotates once.

[0053] 1-6. Examples of supply levels Figure 7 illustrates the method for determining the replenishment level. In this example, the replenishment level is determined such that the lower the toner remaining amount Ta in the developing unit 50, the longer the replenishment posture is maintained. In other words, the lower the toner remaining amount Ta in the developing unit 50, the stronger the replenishment operation. When the toner remaining amount Ta exceeds a predetermined amount T2 (state J1), the replenishment level is determined to be Lv1. When the toner remaining amount Ta is less than or equal to the predetermined amount T2, and also exceeds a predetermined amount T1 (state J2), the replenishment level is determined to be Lv2. When the toner remaining amount Ta is less than or equal to the predetermined amount T1 (state J3), the replenishment level is determined to be Lv3. The amount of replenishment at replenishment level Lv3 is greater than the amount of replenishment at replenishment level Lv2. The amount of replenishment at replenishment level Lv2 is greater than the amount of replenishment at replenishment level Lv1. Thus, the lower the toner remaining amount Ta, the longer the replenishment posture is maintained, making it less likely for toner shortages to occur in the developing unit 50. Image defects formed on the sheet S will also be less likely to occur.

[0054] Thus, the replenishment level changes depending on either or both of the state of the toner supply chamber 53a and the state of the toner cartridge 70. In Figure 7, the state J1 (or state J2) of the toner supply chamber 53a when the remaining toner amount Ta exceeds the first threshold is the first state. The state J2 (or state J3) of the toner supply chamber 53a when the remaining toner amount Ta is less than the first threshold (e.g., T2) is the second state. Note that the state J2 of the toner supply chamber 53a when the remaining toner amount Ta is less than the first threshold and exceeds the second threshold may also be the second state. The state J3 of the toner supply chamber 53a when the remaining toner amount Ta is less than the second threshold is the third state.

[0055] In the replenishment mode performed when the toner supply chamber 53a is in the first state, the time for the rotary body 90 to assume the replenishment position is set to the first time. In the replenishment mode performed when the toner supply chamber 53a is in the second state, the time for the rotary body 90 to assume the replenishment position is set to the second time. The second time is longer than the first time. In the replenishment mode performed when the toner supply chamber 53a is in the third state, the time for the rotary body 90 to assume the replenishment position is the third time. The third time is longer than the second time.

[0056] 1-7. Flowchart Figure 8 shows the control method executed by the CPU 501 according to the control program. Here, a monochrome print job is assumed in which the image is formed using only black toner. The remaining toner amount of the developing unit 50k is taken into consideration, but the remaining toner amount Tb of the toner cartridge 70k is not taken into consideration.

[0057] In step S801, the CPU 501 moves the rotary body 90 from the standby position to the black development position. For example, the CPU 501 controls the motor M1 to rotate the rotary body 90. The motor M1 is supplied with a predetermined number of drive pulses from the controller 500. Here, the predetermined number is the number of pulses that corresponds to moving the rotary body 90 from the standby position to the black development position.

[0058] At step S802, the CPU 501 starts image formation. That is, the CPU 501 controls the image forming apparatus 1 based on the image data and forms a monochrome image on the sheet S.

[0059] In S803, the CPU 501 determines, based on the detection result of the sensor 503k, whether the toner level Ta of the developing unit 50k has fallen below a predetermined amount T1. The toner level Ta is acquired when the rotary body 90 is in the black developing position. However, the timing of acquiring the toner level Ta does not necessarily have to be when the black unit is in the developing position. The toner level Ta may be acquired at any position between the time the rotary body 90 passes through the replenishment position and when it enters the developing position. The sensor 503k that acquires the toner level Ta detects the toner level Ta as an analog quantity. Alternatively, the sensor 503k outputs "00" when the toner level Ta falls below a predetermined amount T1. The sensor 503k outputs "01" when the toner level Ta exceeds a predetermined amount T1 and falls below a predetermined amount T2. The sensor 503k outputs "10" or "11" when the toner level Ta exceeds a predetermined amount T2. If the toner level Ta is not below the predetermined amount T1, CPU 501 proceeds from S803 to S805. If the toner level Ta is less than the predetermined amount T1, CPU 501 proceeds from S803 to S804.

[0060] In S804, the CPU 501 interrupts image formation in the image forming apparatus 1 and performs a replenishment operation. The CPU 501 interrupts image formation by stopping the motor M3. At this time, the CPU 501 controls the motor M4 to separate the rotary body 90 from the photosensitive drum 2. Furthermore, the replenishment control unit 517 replenishes toner from the toner cartridge 70k to the developing unit 50k by rotating the rotary body 90 N times. N is a natural number. For example, N is 1. In other words, the replenishment level of the replenishment operation performed during the interruption is Lv1. This will reduce the interruption time. Here, the replenishment level is fixed at Lv1, but this is just an example. For example, the replenishment level may be fixed at Lv2 or Lv3. Furthermore, the CPU 501 may dynamically determine the replenishment level according to the remaining toner amount Ta.

[0061] In step S805, the CPU 501 instructs the image forming apparatus 1 to resume image formation. The CPU 501 controls the motor M4 to bring the rotary body 90 into contact with the photosensitive drum 2. Furthermore, it restarts the motor M3 to resume the rotation of the photosensitive drum 2 and other components.

[0062] In S806, the CPU 501 determines whether image formation is complete. For example, in a print job to form images on a predetermined number of sheets S (e.g., M sheets), the CPU 501 determines that image formation is complete when images have been formed on all M sheets S. In this case, the CPU 501 proceeds from S806 to S807. If there are still sheets S on which images have not been formed, the CPU 501 returns from S806 to S802 and starts forming images on the next sheet S.

[0063] In S807, the CPU 501 determines the replenishment level based on the remaining toner amount Ta obtained by the sensor 503k. In other words, the CPU 501 determines the replenishment level according to the remaining toner state of the developing unit 50. As shown in Figure 7, the level determination unit 514 determines the replenishment level by comparing the remaining toner amount Ta with predetermined amounts T1 and T2. A formula, table, or program module may be used to convert the remaining toner amount Ta to the replenishment level Lv.

[0064] In the S808, the CPU 501 performs a refueling operation according to the determined refueling level Lv. Refueling level Lv1 is, for example, a level that rotates the rotary body 90 once. This causes the rotary body 90 to assume the refueling position once before transitioning to the standby position. Refueling level Lv2 is a level that rotates the rotary body 90 twice. In this case, the rotary body 90 assumes the refueling position twice before transitioning to the standby position. Refueling level Lv3 is, for example, a level that rotates the rotary body 90 three times. In this case, the rotary body 90 assumes the refueling position three times before transitioning to the standby position. In other words, the higher the refueling level, the greater the amount of rotation of the rotary body 90. Furthermore, the higher the refueling level, the longer the time the rotary body 90 maintains the refueling position may also increase.

[0065] In the first embodiment, the lower the toner level Ta in the developing unit 50, the more effective (higher performance) the replenishment operation is performed. This makes it less likely for the toner level Ta in the developing unit 50 to run out. Therefore, even if the same monochrome print job is executed again, it becomes less likely for the developing unit 50 to run out of toner. For example, even if image formation is performed continuously with black toner, it will be less likely for image formation to be interrupted, or the timing of the interruption will be delayed. The higher the toner level Ta in the developing unit 50, the lower the replenishment level Lv will be selected. In other words, the higher the toner level Ta in the developing unit 50, the less replenishment is required. This means that the execution time of the replenishment operation after image formation is completed will be reduced.

[0066] Incidentally, an image forming apparatus may perform a first image forming operation based on a first job and a second image forming operation based on a second job received after the first job. In this case, the replenishment operation is performed at least one of the following: after the first image forming operation, after the second image forming operation, before the first image forming operation, or before the second image forming operation. The preparation operation after the image forming operation is called a post-rotation. The preparation operation before the image forming operation is called a pre-rotation. That is, the replenishment operation is performed during either the post-rotation or the pre-rotation.

[0067] 2. Second Example In the first embodiment, the amount of toner supplied is adjusted according to the remaining toner amount Ta in the developing unit 50. However, this is only one example; instead of the remaining toner amount Ta in the developing unit 50, the remaining toner amount Tb in the toner cartridge 70 may be considered. Furthermore, both the remaining toner amount Ta and the remaining toner amount Tb may be considered. Therefore, in the second embodiment, a control method that considers both the remaining toner amount Ta and the remaining toner amount Tb will be described. Since the common parts between the second embodiment and the first embodiment have already been described, that description will be omitted in the second embodiment.

[0068] 2-1. Flowchart Figure 9 is a flowchart of the control method in the second embodiment. In Figure 9, S807 shown in Figure 8 is replaced with S907. In S907, the CPU 501 (level determination unit 514) determines the replenishment level Lv based on the remaining toner amounts Ta and Tb of the developing unit 50. The level determination unit 514 determines the replenishment level Lv corresponding to the remaining toner amounts Ta and Tb using a formula, table, or program module that takes the remaining toner amounts Ta and Tb as input and outputs the replenishment level Lv. It was explained that in the first embodiment, when proceeding from S803 to S804, the replenishment level executed in S804 is Lv1. Furthermore, it was explained that in the first embodiment, this replenishment level may be determined according to the remaining toner amount Ta. In the second embodiment, the remaining toner amount Tb may also be considered. In this case, the replenishment level of the replenishment operation executed in S804 is determined based on the remaining toner amounts Ta and Tb, similar to S907.

[0069] 2-2.Predetermined amount T3, T4 Figures 10(A) and 10(B) illustrate predetermined amounts T3 and T4 compared to the remaining toner amount Tb. Here, black toner is explained as an example, but the same applies to other colors. In Figure 10(A), the rotary unit 90 is in the black developing position. In Figure 10(B), the rotary unit 90 is in the black developing position.

[0070] The predetermined amount T3 is the amount of toner at which the amount of toner supplied becomes extremely small as the remaining toner amount Tb in the toner cartridge 70 decreases. As shown in Figure 10(B), the predetermined amount T3 is the amount of toner contained in the toner cartridge 70 when the toner interface (upper surface) is at one end 71f of the discharge opening 71b in the replenishment position. As shown in Figure 10(A), the position of the upper surface of the toner when the toner amount Tb is the predetermined amount T3 in the development position is indicated by a dashed line. When the amount falls below the predetermined amount T3, the amount of toner near the discharge opening 71b in the replenishment position decreases. In other words, the amount of toner supplied from the toner cartridge 70 to the development unit 50 during the replenishment operation becomes extremely small.

[0071] As shown in Figure 10(A), the predetermined amount T4 is greater than the predetermined amount T3. The predetermined amount T4 is the amount of toner at which the amount of toner supplied becomes extremely large as the remaining toner amount Tb in the toner cartridge 70 increases. The dashed line indicates the predetermined amount T4. In other words, the predetermined amount T4 is the amount of toner at which the toner interface is located at one end 71f of the discharge opening 71b in the developing position. When the remaining toner amount Tb exceeds the predetermined amount T4, toner is more easily supplied to the developing unit 50 when transitioning from the supply position to the developing position, and the amount of toner supplied to the toner cartridge 70 can become extremely large.

[0072] 2-3. How to determine supply levels Figure 11 shows the relationship between toner amounts Ta and Tb and replenishment level Lv. To make these relationships visually clearer, the remaining toner in the developing unit 50 and the remaining toner in the developing cartridge 70 are shown.

[0073] In Figure 11, the remaining toner levels of the developing unit 50 are classified into states J1, J2, and J3 as described in Figure 7. The remaining toner levels of the toner cartridge 70 are classified into states K1, K2, and K3. State K1 is when the remaining toner level Tb exceeds a predetermined amount T4. State K2 is when the remaining toner level Tb is less than or equal to a predetermined amount T4 and exceeds a predetermined amount T3. State K3 is when the remaining toner level Tb is less than or equal to a predetermined amount T3. In Figure 11, the replenishment level is determined according to the combination of the remaining toner levels of the developing unit 50 and the toner cartridge 70.

[0074] If the remaining toner amount Ta exceeds a predetermined amount T2, the replenishment level Lv is determined to the first level Lv1, regardless of the remaining toner amount Tb. In other words, if the remaining toner status of the developer unit 50 is state J1, the replenishment level is determined to be Lv1 regardless of whether the remaining toner status of the toner cartridge 70 is state K1 to K3. If the remaining toner amount Tb exceeds a predetermined amount T4, the replenishment level Lv is determined to be the first level Lv1, regardless of the remaining toner amount Ta. In other words, if the remaining toner status of the toner cartridge 70 is state K1, the replenishment level is determined to be Lv1 regardless of whether the developing unit 50 is state J1 to J3.

[0075] If the remaining toner in the developing unit 50 is in state J2 and the remaining toner in the toner cartridge 70 is in state K1 or K2, the replenishment level is determined to be Lv1. If the remaining toner in the developing unit 50 is in state J2 and the remaining toner in the toner cartridge 70 is in state K3, the replenishment level is determined to be Lv2.

[0076] If the remaining toner in the developing unit 50 is in state J3 and the remaining toner in the toner cartridge 70 is in state K1, the replenishment level is determined to be Lv1. If the remaining toner in the developing unit 50 is in state J3 and the remaining toner in the toner cartridge 70 is in state K2, the replenishment level is determined to be Lv2. If the remaining toner in the developing unit 50 is in state J3 and the remaining toner in the toner cartridge 70 is in state K3, the replenishment level is determined to be Lv3.

[0077] The lower the toner level in the developing unit 50 and the lower the toner level in the toner cartridge 70, the more toner is supplied from the toner cartridge 70 to the developing unit 50. The higher the toner level in the developing unit 50 and the higher the toner level in the toner cartridge 70, the less toner is supplied from the toner cartridge 70 to the developing unit 50.

[0078] Thus, the state of toner cartridge 70 when the remaining toner amount Tb exceeds the third threshold (e.g., T3 or T4) is the third state (e.g., states K2, K1). The state of toner cartridge 70 when the remaining toner amount Tb is less than the third threshold is the fourth state (e.g., states K3, K2).

[0079] In the replenishment mode performed when the developing unit 50, which is the storage unit, is in the second state (e.g., state J2 or J3) and the toner cartridge is in the third state, the time the rotary body 90 takes the replenishment position is the third time (Lv1 or Lv2). In the replenishment mode performed when the developing unit 50 is in the second state and the toner cartridge 70 is in the fourth state, the time the rotary body 89 takes the replenishment position is the fourth time (Lv2 or Lv3). The fourth time (e.g., replenishment levels Lv3, Lv2) is longer than the third time (e.g., replenishment levels Lv2, Lv1).

[0080] Furthermore, the fourth state may be the state K2 of the accommodating portion when the remaining amount of toner in the toner cartridge 70 is smaller than a third threshold value (e.g., T4) and exceeds a fourth threshold value (e.g., T3) that is smaller than the third threshold value. In this case, the state K3 of the toner cartridge 70 when the remaining toner amount Tb in the toner cartridge 70 is smaller than the fourth threshold value is the fifth state. In the supply mode implemented when the toner cartridge 70 is in the fifth state, the time period for which the rotary main body 90 assumes the supply posture is a fifth time period. The CPU 501 executes the supply mode such that the fifth time period (e.g., supply levels Lv3, Lv2) is longer than the fourth time period (e.g., supply levels Lv2, Lv1).

[0081] As described above, the supply level is determined at the timing when the rotary main body 90 shifts from the developing posture to the standby posture, and a supply operation corresponding to the supply level is executed. In particular, the smaller the remaining toner amount Ta in the developing unit 50 is, the supply operation with a higher supply effect is executed. As a result, the remaining toner amount Ta in the developing unit 50 after shifting to the standby posture approaches a substantial upper limit amount of toner. Therefore, even if a plurality of images are continuously printed on the sheet S in a monochrome print job of the same color again, image formation is less likely to be interrupted. Alternatively, the interruption timing can be delayed. Compared with the first embodiment, the second embodiment determines that the supply level Lv is smaller when the remaining toner amount Tb in the toner cartridge 70 is large. Therefore, the execution time of the supply operation after the completion of image formation will be further reduced.

[0082] The conditions shown in Fig. 11 may be changed. The magnitude relationship of A≦B may be replaced with the magnitude relationship of A<B. Conversely, the magnitude relationship of A<B may be replaced with the magnitude relationship of A≦B. The statement "a certain value is equal to or greater than a threshold value" may be replaced with "a certain value exceeds the threshold value". The statement "a certain value is equal to or less than a threshold value" may be replaced with "a certain value is less than the threshold value".

[0083] 3. Modifications In the first and second embodiments, the replenishment level Lv is determined at the timing when the rotary body 90 returns from the developing position to the standby position after image formation is complete, and the replenishment operation is executed. However, this is just one example. For example, the event monitoring unit 515 may detect another event unrelated to the remaining toner amounts Ta and Tb in the middle of a monochrome job. Another event could be an error event that interrupts the print job, such as a jam in the sheet S or an abnormal temperature rise in the fuser 40. In this case, the replenishment control unit 517 executes S807 or S907 and S808 as a replenishment operation during the interruption of the print job caused by the error event. This makes it less likely for subsequent interruptions of the monochrome job to occur, or delays the timing of the interruption.

[0084] In the first and second embodiments, it is assumed that only the toner cartridge 70 is replaceable, and the developer unit 50 is not. When only the toner cartridge 70 is replaceable, immediately after replacing the toner cartridge 70, the toner level Ta in the developer unit 50 tends to be low, while the toner level Tb in the toner cartridge 70 tends to be high. In other words, when only the toner cartridge 70 is replaceable, the effects of this embodiment are often obtained. However, the first and second embodiments are also applicable even if the toner cartridge 70 and the developer unit 50 are integrated.

[0085] In the first and second embodiments, the higher the replenishment level Lv, the greater the number of rotations of the rotary body 90, thereby increasing the total time the replenishment position is maintained. However, this is only one example. For example, instead of, or along with, the number of rotations of the rotary body 90 may be adjusted, the rotational speed in the replenishment position may be adjusted. For example, the higher the replenishment level Lv, the greater the rotational speed in the replenishment position may be reduced. Alternatively, the replenishment control unit 517 may stop the rotary body 90 in the replenishment position. In this case, the higher the replenishment level Lv, the greater the stopping time may be increased.

[0086] In the first and second embodiments, predetermined amounts T1 and T2 are provided for the developing unit 50; however, only one of these predetermined amounts may be adopted. Furthermore, three or more predetermined amounts may be adopted. When n predetermined amounts are adopted, it becomes possible to determine n+1 replenishment levels, where n is a natural number greater than or equal to 1. The same applies to the predetermined amounts T3 and T4 for the toner cartridge 70 in the second embodiment. Only one of these predetermined amounts may be adopted. Furthermore, three or more predetermined amounts may be adopted.

[0087] In the first and second embodiments, the remaining toner amounts Ta and Tb are detected by a sensor device or calculated by the CPU 501. Furthermore, the same method may be used for each of the predetermined amounts T1 to T4, or different methods may be applied. The comparison result between the remaining toner amount Ta and the predetermined amount T1 is detected by sensor 503. The comparison result between the remaining toner amount Ta and the predetermined amount T2 is detected by counter 505. The comparison results between the remaining toner amount Tb and the predetermined amounts T3 and T4 are detected by counter 506. This is just one example. The comparison result between the remaining toner amount Ta and the predetermined amount T1 may also be calculated using counter 505. The comparison result between the remaining toner amount Ta and the predetermined amount T2 may be detected by sensor 503. The comparison results between the remaining toner amount Tb and the predetermined amounts T3 and T4 may be detected by sensor 504. Note that the method using sensors 503 and 504 is advantageous in terms of detection accuracy compared to the method using counters 505 and 506. The method using counters 505 and 506 is advantageous in terms of manufacturing cost compared to the method using sensors 503 and 504.

[0088] In the first and second embodiments, the remaining toner amounts Tby, Tbm, Tbc, and Tbk of the toner cartridge 70 are stored in memories 507y, 507m, 507c, and 507k, respectively. However, this is just one example. For example, the remaining toner amounts Tby, Tbm, Tbc, and Tbk may be stored in memory 502. In this case, when the toner cartridge 70 is replaced with a new one, the remaining toner amount Tb is reset. For example, the CPU 501 detects that the toner cartridge 70 has been replaced with a new one by monitoring the unique identification information (e.g., manufacturing serial number) of the toner cartridge 70 stored in memory 507. If the unique identification information read last time is different from the unique identification information read this time, it can be determined that a replacement with a new one has been performed.

[0089] Although the above embodiment describes a monochrome print job, it is also applicable to color print jobs. In this case, in S803, when the toner level Ta of at least one of the four toners falls below a predetermined value T1, a replenishment operation is performed. As a result, not only the toner of the one color whose toner level Ta falls below the predetermined value T1 is replenished, but also the toners of the other colors. This is because the rotary body 90 rotates at least once during the replenishment operation. In S807 and S907, replenishment levels Lvy, Lvm, Lvc, and Lvk are determined for each of the four colors. In S808, a replenishment operation is performed according to the highest replenishment level among the replenishment levels Lvy, Lvm, Lvc, and Lvk. The replenishment operation does not depend on the number of rotations, but on the stop time or the rotation speed in the replenishment position. In this case, for each toner color, the stop time or rotation speed is determined according to the corresponding replenishment level Lv.

[0090] In the embodiment described above, the replenishment level Lv is defined such that the replenishment amount increases as the replenishment level Lv increases. However, this is just one example. The replenishment level Lv may also be defined such that the replenishment amount increases as the replenishment level Lv decreases. In any case, it is sufficient that a more enhanced replenishment operation is performed as the remaining toner levels Ta and Tb decrease.

[0091] 4. Remarks The developing assembly 400 is an example of a developing means having a first container (e.g., toner cartridge 70) for containing toner and a second container (e.g., developing unit 50) for containing toner supplied from the first container. The rotary body 90 is an example of a rotating body that rotates while holding a plurality of developing assemblies 400. The photosensitive drum 2 is an example of an image carrier that is positioned opposite the rotating body and carries an image to be developed by toner supplied from one of the plurality of developing means positioned at the developing position. The motor M1 is an example of a driving means that rotates the rotating body to position one of the developing means at the developing position, or to position each of the plurality of developing means in a standby position not facing the image carrier. The controller 500 is an example of a control means that controls the amount of toner supplied from the first container to the second container in the developing means to be supplied, according to the remaining amount of toner in the developing means to be supplied among the plurality of developing means. This improves the toner supply operation.

[0092] The controller 500 rotates the rotary body 90 via the motor M1, causing the developing assembly 400 to pass through a predetermined rotation range (replenishment position). This causes toner to fall from the toner cartridge 70 of the developing assembly 400 to the developing unit 50. As a result, the mechanism for performing the replenishment operation is simplified.

[0093] The CPU 501, acquisition unit 511, sensors 503 and 504, and counters 506 and 507 are examples of acquisition means for acquiring toner levels Ta and Tb.

[0094] The lower the toner level Ta in the developing unit 50, the longer the replenishment position is maintained. This should reduce the likelihood of image defects caused by insufficient toner.

[0095] The toner replenishment operation when the toner level Ta of the developing unit 50 does not exceed a threshold (e.g., a predetermined value T1) is more powerful than the toner replenishment operation when the toner level Ta exceeds the threshold. The controller 500 performs the replenishment operation by rotating the rotary body 90 via the motor M1. In this way, controlling the replenishment amount using a threshold simplifies the replenishment control.

[0096] As illustrated in Figure 7, the amount of toner replenished when the toner level Ta does not exceed the first threshold (e.g., predetermined value T1) is greater than the amount of toner replenished when the toner level Ta exceeds the first threshold but does not exceed the second threshold (e.g., predetermined value T2). The amount of toner replenished when the toner level Ta exceeds the first threshold but does not exceed the second threshold is greater than the amount of toner replenished when the toner level Ta exceeds the second threshold. As a result, the toner level Ta in the developing unit 50 will be maintained at an appropriate amount.

[0097] In the first and second embodiments, predetermined values ​​T1 and T2 are exemplified, but more thresholds may be used. For example, the toner replenishment operation when the toner level Ta exceeds the first threshold but does not exceed the second threshold is stronger than the toner replenishment operation when the toner level Ta exceeds the second threshold but does not exceed the third threshold T5. The toner replenishment operation when the toner level Ta exceeds the second threshold but does not exceed the third threshold T5 is stronger than the toner replenishment operation when the toner level Ta exceeds the third threshold T5. In other words, the more toner level Ta there is, the less toner is replenished. The less toner level Ta there is, the longer the replenishment posture is maintained.

[0098] In the first and second embodiments, two threshold values ​​(predetermined values ​​T1 and T2) are used for the toner remaining amount Ta, but this is merely an example. One threshold value, such as either predetermined value T1 or predetermined value T2, may be used.

[0099] As described in the second embodiment, the supply amount and the supply operation are determined using the remaining toner amount Tb in the toner cartridge 70, the first threshold value and the second threshold value (e.g., predetermined values T3, T4). As suggested in FIG. 11, the supply operation when T3 < Tb is more enhanced than the supply operation when T4 < Tb < T3. The supply operation when T4 < Tb < T3 is more enhanced than the supply operation when T4 < Tb. That is, the smaller the remaining toner amount Tb is, the more the number of times of performing the supply operation is increased. This increases the time for which the supply posture is maintained. It should be noted that the larger the remaining toner amount Tb is, the more the number of times of performing the supply operation may be reduced.

[0100] A replenishment level determined based on the remaining amount of toner is employed. For example, the replenishment level is defined such that as the replenishment level increases, the time for which the replenishment posture is maintained increases. The replenishment level is defined such that as the replenishment level increases, the replenishment operation is enhanced.

[0101] As exemplified in FIG. 7, when the remaining toner amount Ta does not exceed the predetermined value T1 (or T2), the replenishment level Lv is determined to be Lv3 (or Lv2). When the remaining toner amount Ta does not exceed the predetermined value T1 (or T2), the replenishment level Lv is determined to be Lv2 (or Lv1).

[0102] As shown in FIG. 7, when Ta < T1, the replenishment level Lv is determined to be Lv3. When T1 < Ta < T2, the replenishment level Lv is determined to be Lv2. When T2 < Ta, the replenishment level Lv is determined to be Lv1. That is, the higher the replenishment level Lv is, the more enhanced replenishment operation is performed. The smaller the remaining toner amount Ta is, the more enhanced replenishment operation is performed.

[0103] As shown in FIG. 11, when Ta < T1 and Tb < T3, the supply level is determined to be Lv3. When Ta < T1 and T3 < Tb < T4, the supply level is determined to be Lv2. When T1 < Ta < T2 and Tb < T3, the supply level is determined to be Lv2. When T2 < Ta, the supply level is determined to be Lv1. When T4 < Tb, the supply level is determined to be Lv1. Here, the supply operation at supply level Lvi+1 is enhanced compared to the supply operation at supply level Lvi. i is a natural number. As described above, by considering both the remaining toner amount Ta of the developing unit 50 and the remaining toner amount Tb of the toner cartridge 70, the supply operation can be performed more appropriately. As a result, image defects will be reduced, or the execution time of the supply operation will be reduced. Further, the number of times forced supply operations are performed due to interruption of image formation will be reduced.

[0104] As suggested in FIG. 11, when T1 < Ta < T2 and T3 < Tb < T4, the supply level is determined to be Lv1.

[0105] As shown in FIG. 4, the discharge opening 71b of the toner cartridge 70 is an example of the first opening of the first container. The receiving opening 53b is an example of the second opening of the second container. The toner cartridge 70 supplies toner to the developing unit 50 through the discharge opening 71b and the receiving opening 53b.

[0106] As shown in FIG. 6 and the like, the acquisition unit 511 acquires the remaining toner amount Ta when the developing roller 51 of the developing assembly 400 to be supplied is positioned at the developing position. The rotary body 90 is rotatable 360 degrees. Therefore, it is problematic at which position of the developing unit 50 the remaining toner amount Ta should be measured. In order to suppress or avoid a shortage of the remaining toner amount Ta in the developing unit 50 during development, the remaining toner amount Ta should be measured when the developing unit 50 is positioned at the developing position.

[0107] As mentioned in the first embodiment, the sensor 503 and the detection unit 512 are examples of detection means for detecting the remaining toner amount Ta through a window provided on the wall surface of the developing unit 50. In this case, the window is provided at least one of a position corresponding to a predetermined amount T1 and a position corresponding to a predetermined amount T2.

[0108] The sensor 504 and the detection unit 512 detect the remaining toner amount Tb through a window provided on the wall of the toner cartridge 70. The window is provided at least one of a position corresponding to a predetermined amount T3 and a position corresponding to a predetermined amount T4.

[0109] As explained in relation to Figure 5, the calculation unit 513 is an example of a calculation means that determines the amount of toner consumed by analyzing the image data that forms the basis of the image, accumulates the amount of toner consumed, and calculates the remaining amount of toner based on the accumulated amount of toner consumed.

[0110] As explained with respect to Figure 5, the remaining toner amount Ta is detected by the sensor 503 and the detection unit 512. The remaining toner amount Tb is calculated by the calculation unit 513.

[0111] As shown in Figures 8 and 9, once image formation is complete for M sheets S, a replenishment operation is performed. This reduces the likelihood of replenishment operations being performed during image formation, thus reducing user waiting time.

[0112] When an error event occurs, a replenishment operation is performed. This means that the error event resolution operation and the replenishment operation are performed in parallel. As a result, user waiting time should be reduced.

[0113] Thus, an error event is a jam in the sheet. An error event is an event that interrupts image formation.

[0114] The replenishment operation is performed by rotating the rotary body 90. Therefore, increasing the number of rotations of the rotary body 90 enhances the replenishment operation.

[0115] The replenishment operation includes temporarily reducing the rotational speed of the rotary body 90 within a predetermined rotational range that includes the rotational phase (replenishment position) in which toner is replenished. Increasing the amount of reduction in rotational speed enhances the replenishment operation. Note that increasing the number of rotations and decreasing the rotational speed may be combined.

[0116] The replenishment operation includes stopping the rotary body 90 when the developing unit 50 is located at the replenishment position. The replenishment operation is enhanced by increasing the stopping time. An increase in the number of rotations may be combined with an increase in the stopping time. A temporary decrease in the rotation speed may be combined with an increase in the stopping time. An increase in the number of rotations may be combined with an increase in the stopping time.

[0117] 5. Summary (Item 1) A rotary that allows for the attachment and detachment of a toner cartridge containing toner, comprising a developing roller and a storage section for containing the developer supplied from the toner cartridge, A control unit that controls the rotation of the rotary, Equipped with, The rotary is capable of assuming a supply position in which toner is supplied from the toner cartridge to the storage section. The control unit executes a replenishment mode that rotates the rotary so that it assumes the replenishment position. The state of the storage unit when the remaining amount of toner in the storage unit exceeds a first threshold is defined as the first state. The state of the storage unit when the remaining amount of toner in the storage unit is less than the first threshold is defined as the second state. In the replenishment mode performed when the housing is in the first state, the time during which the rotary assumes the replenishment posture is defined as the first time. In the replenishment mode performed when the housing is in the second state, the time during which the rotary assumes the replenishment posture is defined as the second time. The control unit executes the replenishment mode such that the second time is longer than the first time. An image forming apparatus characterized by the following features. (Item 2) The second state is the state of the storage unit when the remaining amount of toner in the storage unit does not exceed the first threshold and exceeds a second threshold which is smaller than the first threshold. The state of the storage unit when the remaining amount of toner in the storage unit is less than the second threshold is defined as the third state. In the replenishment mode performed when the housing is in the third state, the time during which the rotary assumes the replenishment posture is defined as the third time. The control unit executes the replenishment mode such that the third time is longer than the second time. The image forming apparatus according to item 1, characterized in that it is a picture forming apparatus. (Item 3) The toner cartridge is provided with a first opening. The housing section is provided with a second opening that communicates with the first opening, In the refueling position, the direction from the first opening to the second opening of the rotary includes a downward component in the vertical direction. The image forming apparatus according to item 1, characterized in that it is a picture forming apparatus. (Item 4) In the replenishment mode, the time the rotary assumes the replenishment position is determined based on the remaining toner in the storage unit and the remaining toner in the toner cartridge. The image forming apparatus according to item 1, characterized in that it is a picture forming apparatus. (Item 5) The state of the toner cartridge when the remaining toner amount in the toner cartridge exceeds the third threshold is defined as the third state. The state of the toner cartridge when the remaining toner amount in the toner cartridge is less than the third threshold is defined as the fourth state. In the replenishment mode performed when the storage unit is in the second state and the toner cartridge is in the third state, the time during which the rotary assumes the replenishment posture is set to the third time. In the replenishment mode performed when the housing is in the second state and the toner cartridge is in the fourth state, the time during which the rotary assumes the replenishment posture is defined as the fourth time. The fourth time is longer than the third time. The image forming apparatus according to item 4, characterized in that it is a picture forming apparatus. (Item 6) The image forming apparatus according to any one of items 1 to 5, characterized in that the control unit increases the number of rotations of the rotary to increase the time the rotary assumes the replenishment posture in the replenishment mode. (Item 7) The image forming apparatus according to any one of items 1 to 5, characterized in that the control unit increases the time the rotary is stopped in the replenishment position, thereby increasing the time the rotary assumes the replenishment position in the replenishment mode. (Item 8) The image forming apparatus according to any one of items 1 to 5, characterized in that the control unit slows down the rotational speed of the rotary in the replenishment position to increase the time the rotary assumes the replenishment position in the replenishment mode. (Item 9) The image forming apparatus performs a first image forming operation based on a first job and a second image forming operation based on a second job received after the first job. The replenishment mode is performed at least one of the following: after the first image forming operation, after the second image forming operation, before the first image forming operation, and before the second image forming operation. An image forming apparatus according to any one of items 1 to 5, characterized by the features described above. (Item 10) The rotary is capable of adopting a developing position in which the developing roller can come into contact with the image carrier. When the rotary assumes the developing position, if the remaining toner in the storage unit is less than the second threshold, the control unit interrupts the image forming operation and executes the replenishment mode. The control unit restarts the image forming operation after the replenishment mode is completed. The image forming apparatus according to item 2, characterized in that it is a picture forming apparatus. (Item 11) The fourth state is the state of the storage unit when the remaining amount of toner in the toner cartridge is less than the third threshold and exceeds a fourth threshold that is less than the third threshold. The state in the storage section when the remaining amount of toner in the toner cartridge is less than the fourth threshold is defined as the fifth state. In the replenishment mode performed when the toner cartridge is in the fifth state, the time during which the rotary assumes the replenishment posture is defined as the fifth time. The control unit executes the replenishment mode such that the fifth time is longer than the fourth time. The image forming apparatus according to item 5, characterized in that it is a picture forming apparatus. (Item 12) The image forming apparatus according to item 10, wherein the remaining amount of toner in the storage unit and the remaining amount of toner in the toner cartridge are obtained when the rotary is in the developing position. (Item 13) The image forming apparatus according to item 12, further comprising means for acquiring the remaining amount of toner in the storage unit. (Item 14) The image forming apparatus according to item 12, further comprising means for acquiring the remaining amount of toner in the toner cartridge. (Item 15) The image forming apparatus according to any one of items 1 to 5, further comprising a calculation means for accumulating toner consumption by analyzing image data which is the basis of an image formed on a recording medium by the image forming apparatus, and calculating the remaining toner amount based on the accumulated toner consumption.

[0118] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of symbols]

[0119] 1...Image forming apparatus, 2...Photosensitive drum, 50...Developing unit, 70...Toner cartridge, 500...Controller, M1...Motor

Claims

1. A rotary that allows for the attachment and detachment of a toner cartridge containing toner, comprising a developing roller and a storage section for containing the developer supplied from the toner cartridge, A control unit that controls the rotation of the rotary, Equipped with, The rotary is capable of assuming a supply position in which toner is supplied from the toner cartridge to the storage section. The control unit executes a replenishment mode that rotates the rotary so that it assumes the replenishment position. The state of the storage unit when the remaining amount of toner in the storage unit exceeds a first threshold is defined as the first state. The state of the storage unit when the remaining amount of toner in the storage unit is less than the first threshold is defined as the second state. In the replenishment mode performed when the housing is in the first state, the time during which the rotary assumes the replenishment posture is defined as the first time. In the replenishment mode performed when the housing is in the second state, the time during which the rotary assumes the replenishment posture is defined as the second time. The control unit executes the replenishment mode such that the second time is longer than the first time. An image forming apparatus characterized by the following features.

2. The second state is the state of the storage unit when the remaining amount of toner in the storage unit is less than the first threshold and exceeds a second threshold that is less than the first threshold. The state of the storage unit when the remaining amount of toner in the storage unit is less than the second threshold is defined as the third state. In the replenishment mode performed when the housing is in the third state, the time during which the rotary assumes the replenishment posture is defined as the third time. The control unit executes the replenishment mode such that the third time is longer than the second time. The image forming apparatus according to feature 1.

3. The toner cartridge is provided with a first opening. The housing section is provided with a second opening that communicates with the first opening, In the refueling position, the direction from the first opening to the second opening of the rotary includes a downward component in the vertical direction. The image forming apparatus according to feature 1.

4. In the replenishment mode, the time the rotary assumes the replenishment position is determined based on the remaining toner in the storage unit and the remaining toner in the toner cartridge. The image forming apparatus according to feature 1.

5. The state of the toner cartridge when the remaining toner amount in the toner cartridge exceeds the third threshold is defined as the third state. The state of the toner cartridge when the remaining toner amount in the toner cartridge is less than the third threshold is defined as the fourth state. In the replenishment mode performed when the storage unit is in the second state and the toner cartridge is in the third state, the time during which the rotary assumes the replenishment posture is set to the third time. In the replenishment mode performed when the housing is in the second state and the toner cartridge is in the fourth state, the time during which the rotary assumes the replenishment posture is defined as the fourth time. The fourth time is longer than the third time. The image forming apparatus according to feature 4.

6. The image forming apparatus according to any one of claims 1 to 5, characterized in that the control unit increases the number of rotations of the rotary to increase the time the rotary assumes the replenishment posture in the replenishment mode.

7. The image forming apparatus according to any one of claims 1 to 5, characterized in that the control unit increases the time the rotary is stopped in the replenishment position, thereby increasing the time the rotary assumes the replenishment position in the replenishment mode.

8. The image forming apparatus according to any one of claims 1 to 5, characterized in that the control unit slows down the rotational speed of the rotary in the replenishment position to increase the time the rotary assumes the replenishment position in the replenishment mode.

9. The image forming apparatus performs a first image forming operation based on a first job and a second image forming operation based on a second job received after the first job. The replenishment mode is performed at least one of the following: after the first image forming operation, after the second image forming operation, before the first image forming operation, and before the second image forming operation. The image forming apparatus according to any one of claims 1 to 5.

10. The rotary is capable of adopting a developing position in which the developing roller can come into contact with the image carrier. When the rotary assumes the developing position, if the remaining toner in the storage unit is less than the second threshold, the control unit interrupts the image forming operation and executes the replenishment mode. The control unit restarts the image forming operation after the replenishment mode is completed. The image forming apparatus according to feature 2.

11. The fourth state is the state of the storage unit when the remaining amount of toner in the toner cartridge is less than the third threshold and exceeds a fourth threshold that is less than the third threshold. The state of the toner cartridge when the remaining amount of toner in the toner cartridge is less than the fourth threshold is defined as the fifth state. In the replenishment mode performed when the toner cartridge is in the fifth state, the time during which the rotary assumes the replenishment posture is defined as the fifth time. The control unit executes the replenishment mode such that the fifth time is longer than the fourth time. The image forming apparatus according to feature 5.

12. The image forming apparatus according to claim 10, wherein the remaining amount of toner in the storage unit and the remaining amount of toner in the toner cartridge are obtained when the rotary is in the developing position.

13. The image forming apparatus according to claim 12, further comprising an acquisition means for acquiring the remaining amount of toner in the storage unit.

14. The image forming apparatus according to claim 12, further comprising means for acquiring the remaining amount of toner in the toner cartridge.

15. The image forming apparatus according to any one of claims 1 to 5, further comprising a calculation means for accumulating toner consumption by analyzing image data which is the basis of an image formed on a recording medium by the image forming apparatus, and calculating the remaining toner amount based on the accumulated toner consumption.

Images