Image forming apparatus and method for controlling image forming apparatus

Abstract

An image forming device and a method for controlling an image forming device. An image forming device according to one embodiment includes a photosensitive drum, an exposure device, a developer, a toner supply motor, and a processor. The exposure device exposes the photosensitive drum based on image data. The developer forms a toner image on the photosensitive drum using toner supplied from a toner cartridge. The toner supply motor supplies toner from the toner cartridge to the developer. The processor detects that the toner is exhausted when a toner supply rate calculated based on the cumulative value of pixel count values of the image data and the cumulative value of the drive time of the toner supply motor is less than a predetermined threshold value.

Description

Technical Field

[0001] Embodiments of the present invention generally relate to an image forming apparatus and a method for controlling the image forming apparatus. Background Art

[0002] The image forming apparatus performs an image forming process in which it receives toner from a toner cartridge, forms a toner image on a photosensitive drum, and transfers the toner image on the photosensitive drum to a print medium.

[0003] The image forming apparatus calculates the remaining amount of toner in the toner cartridge based on the drive amount (drive time) of a motor (toner supply motor) for rotating a screw that delivers toner from the toner cartridge to the image forming apparatus. When the remaining amount of toner is less than a near-end threshold, the image forming apparatus detects that the toner is near end, indicating that little toner remains in the toner cartridge. In addition, the image forming apparatus includes a toner concentration sensor that detects the toner concentration in a developer that receives toner from the toner cartridge. When the image forming apparatus detects that the toner concentration has decreased, it supplies toner via the toner supply motor. When the image forming apparatus detects that the toner concentration has not recovered even though the toner supply motor is activated, it detects that the toner in the toner cartridge is exhausted, indicating that the toner is exhausted.

[0004] However, when determining toner end based on toner density, there is a problem in that the number of printed sheets from detection of toner near end to detection of toner end varies depending on the print rate of the image data used for printing. Summary of the Invention

[0005] An image forming device comprises: a photosensitive drum; an exposing device for exposing the photosensitive drum based on image data; a developing device for forming a toner image on the photosensitive drum using toner supplied from a toner cartridge; a toner supply motor for supplying toner from the toner cartridge to the developing device; and a processor for detecting that the toner is exhausted when a toner supply rate calculated based on an accumulated value of pixel count values of the image data and an accumulated value of a driving time of the toner supply motor is less than a preset threshold value.

[0006] A method for controlling an image forming device, wherein the image forming device comprises: a photosensitive drum; an exposure device for exposing the photosensitive drum based on image data; a developer for forming a toner image on the photosensitive drum using toner supplied from a toner cartridge; a toner supply motor for supplying toner from the toner cartridge to the developer; and a processor for detecting that the toner is exhausted when a toner supply rate calculated based on an accumulated value of pixel count values of the image data and an accumulated value of a driving time of the toner supply motor is less than a predetermined threshold value. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 A diagram for explaining a configuration example of an image forming apparatus according to an embodiment.

[0008] Figure 2 This is a diagram for explaining a configuration example of a portion of an image forming unit according to an embodiment.

[0009] Figure 3 This is an explanatory diagram for explaining an example of the operation of the image forming apparatus according to one embodiment.

[0010] Figure 4 This is an explanatory diagram for explaining an example of the operation of the image forming apparatus according to one embodiment.

[0011] Figure 5 This is an explanatory diagram for explaining an example of the operation of the image forming apparatus according to one embodiment.

[0012] Figure 6 This is an explanatory diagram for explaining an example of the operation of the image forming apparatus according to one embodiment.

[0013] Figure 7 This is an explanatory diagram for explaining an example of the operation of the image forming apparatus according to one embodiment.

[0014] Description of reference numerals:

[0015] 1. Image forming device; 2. Toner cartridge; 11. Housing; 12. Communication interface; 13. System controller; 14. Display unit; 15. Operation interface; 16. Paper tray; 17. Paper discharge tray; 18. Conveyor unit; 19. Image forming unit; 20. Fuser; 21. Processor; 22. Memory; 31. Paper feed path; 32. Paper discharge path; 33. Pickup roller; 41. Loading unit; 42. Processing unit; 43. Exposure unit; 44. Transfer unit Printing mechanism; 51. Toner containing container; 52. Toner feeding mechanism; 61. Toner supply motor; 71. Photosensitive drum; 72. Cleaner; 73. Charger; 74. Developer; 81. Developer container; 82. Stirring mechanism; 83. Developing roller; 84. Scraper; 85. ATC sensor; 91. Primary transfer belt; 92. Secondary transfer opposing roller; 93. Primary transfer roller; 94. Secondary transfer roller; 95. Heating roller; 96. Pressurizing roller. DETAILED DESCRIPTION

[0016] An image forming apparatus according to one embodiment includes a photosensitive drum, an exposure device, a developer, a toner supply motor, and a processor. The exposure device exposes the photosensitive drum based on image data. The developer forms a toner image on the photosensitive drum using toner supplied from a toner cartridge. The toner supply motor supplies toner from the toner cartridge to the developer. The processor detects toner exhaustion when a toner supply rate, calculated based on the cumulative pixel count of the image data and the cumulative drive time of the toner supply motor, falls below a predetermined threshold.

[0017] Hereinafter, an image forming apparatus and a method for controlling the image forming apparatus according to an embodiment will be described with reference to the drawings.

[0018] Figure 1 It is an explanatory diagram for explaining a configuration example of the image forming apparatus 1 according to one embodiment.

[0019] The image forming apparatus 1 is, for example, a multifunction printer (MFP) that performs various processes such as image formation while conveying a recording medium such as a print medium. The image forming apparatus 1 is, for example, a solid-state scanning printer (e.g., an LED printer) that uses a scanning LED array to convey a recording medium such as a print medium while conveying various processes such as image formation.

[0020] For example, the image forming apparatus 1 receives toner from the toner cartridge 2 and forms an image on a print medium using the received toner. The toner may be a monochrome toner or a color toner such as cyan, magenta, yellow, or black.

[0021] like Figure 1As shown, the image forming apparatus 1 includes a housing 11 , a communication interface 12 , a system controller 13 , a display unit 14 , an operation interface 15 , a plurality of paper trays 16 , a paper discharge tray 17 , a conveying unit 18 , an image forming unit 19 , and a fixing unit 20 .

[0022] The housing 11 is a main body of the image forming apparatus 1 and houses a communication interface 12 , a system controller 13 , a display unit 14 , an operation interface 15 , a plurality of paper trays 16 , a paper discharge tray 17 , a conveying unit 18 , an image forming unit 19 , and a fixing unit 20 .

[0023] The communication interface 12 is an interface for communicating with other devices. For example, the communication interface 12 is used to communicate with a host device (external device). For example, the communication interface 12 is configured as a LAN connector. Alternatively, the communication interface 12 can wirelessly communicate with other devices using standards such as Bluetooth (registered trademark) or Wi-Fi (registered trademark).

[0024] The system controller 13 controls the image forming apparatus 1. The system controller 13 includes, for example, a processor 21 and a memory 22.

[0025] The processor 21 is a computing element that performs arithmetic processing. The processor 21 is, for example, a CPU. The processor 21 performs various processes based on data such as programs stored in the memory 22. The processor 21 functions as a control unit capable of performing various operations by executing the programs stored in the memory 22.

[0026] The memory 22 is a storage medium that stores programs and data used in the programs. In addition, the memory 22 also functions as a working memory. That is, the memory 22 temporarily stores data being processed by the processor 21 and programs executed by the processor 21.

[0027] The processor 21 performs various information processing by executing programs stored in the memory 22. For example, the processor 21 generates a print job based on an image acquired from an external device via the communication interface 12. The processor 21 stores the generated print job in the memory 22.

[0028] A print job includes image data representing an image to be formed on a print medium P. The image data may be data for forming an image on a single print medium P or data for forming images on multiple print media P. Furthermore, a print job includes information indicating whether color printing or monochrome printing is to be performed.

[0029] The processor 21 also functions as a controller (engine controller) that controls the operations of the transport unit 18, the image forming unit 19, and the fuser 20 by executing programs stored in the memory 22. Specifically, the processor 21 controls the transport unit 18 to transport the print medium P, the image forming unit 19 to form an image on the print medium P, and the fuser 20 to fuse the image onto the print medium P.

[0030] Alternatively, the image forming apparatus 1 may include an engine controller independently of the system controller 13. In this case, the engine controller controls the conveyance of the print medium P by the conveyance unit 18, the formation of an image on the print medium P by the image forming unit 19, and the fixing of the image on the print medium P by the fuser 20. In this case, the system controller 13 supplies information required for control by the engine controller to the engine controller.

[0031] The display unit 14 includes a display that displays screen images based on image signals input from a display control unit such as the system controller 13 or a graphic controller (not shown). For example, the display unit 14 displays screen images for various settings of the image forming apparatus 1 and information such as the remaining toner level.

[0032] The operation interface 15 is connected to an operating member (not shown). The operation interface 15 supplies an operation signal corresponding to the operation of the operating member to the system controller 13. The operating member may be, for example, a touch sensor, a numeric keypad, a power key, a paper feed key, various function keys, or a keyboard. The touch sensor acquires information indicating a designated position within a certain area. The touch sensor is integrally formed with the display unit 14 as a touch panel, and inputs a signal indicating the touched position on the screen displayed by the display unit 14 to the system controller 13.

[0033] The plurality of paper trays 16 are cassettes that respectively accommodate printing media P. The paper trays 16 are configured to be able to supply the printing media P from the outside of the housing 11 . For example, the paper trays 16 are configured to be able to be pulled out from the housing 11 .

[0034] The paper discharge tray 17 is a tray that supports the print medium P discharged from the image forming apparatus 1 .

[0035] Next, a configuration for conveying the printing medium P of the image forming apparatus 1 will be described.

[0036] The transport unit 18 is a mechanism for transporting the printing medium P within the image forming apparatus 1. Figure 1 As shown, the transport unit 18 includes a plurality of transport paths. For example, the transport unit 18 includes a paper feed transport path 31 and a paper discharge transport path 32.

[0037] The paper feed path 31 and paper discharge path 32 are each composed of multiple motors, multiple rollers, and multiple guides (not shown). The multiple motors rotate shafts under the control of the system controller 13, which in turn rotates the rollers in conjunction with the shaft rotation. The rotation of the multiple rollers moves the print medium P. The multiple guides control the conveyance direction of the print medium P.

[0038] The paper feed conveyor path 31 receives print media P from the paper tray 16 and supplies the received print media P to the image forming unit 19. The paper feed conveyor path 31 includes pickup rollers 33 corresponding to each paper tray. Each pickup roller 33 receives print media P from the paper tray 16 into the paper feed conveyor path 31.

[0039] The paper discharge conveyance path 32 is a conveyance path for discharging the print medium P on which an image is formed from the housing 11 . The print medium P discharged from the paper discharge conveyance path 32 is supported by the paper discharge tray 17 .

[0040] Next, the image forming section 19 will be described.

[0041] The image forming unit 19 is a configuration for forming an image on the print medium P. Specifically, the image forming unit 19 forms an image on the print medium P based on a print job generated by the processor 21 .

[0042] The image forming unit 19 includes a plurality of loading units 41, a plurality of processing units 42, a plurality of exposure devices 43, and a transfer mechanism 44. The image forming unit 19 includes a loading unit 41 and an exposure device 43 for each processing unit 42. Since the processing units 42, the loading units 41, and the exposure devices 43 have the same structure, the following description will use one processing unit 42, one loading unit 41, and one exposure device 43 as an example.

[0043] Figure 2 It is an explanatory diagram for explaining an example of a configuration of a part of the image forming unit 19 .

[0044] First, the toner cartridge 2 mounted in the loading portion 41 will be described.

[0045] like Figure 2 As shown, the toner cartridge 2 includes a toner storage container 51 and a toner delivery mechanism 52. In addition, the toner cartridge 2 includes an IC chip (not shown).

[0046] The toner storage container 51 is a container that stores toner.

[0047] The toner delivery mechanism 52 is a mechanism for delivering the toner in the toner storage container 51. The toner delivery mechanism 52 is, for example, a screw provided in the toner storage container 51 and delivering the toner by rotating.

[0048] The IC chip includes a memory pre-stored with various control data. Examples of the control data include an "identification code" and a "near-end threshold." The "identification code" indicates the type and model of the toner cartridge 2. The "near-end threshold" is a threshold used by the image forming apparatus 1 to determine whether the remaining toner in the toner cartridge 2 is low.

[0049] Next, the loading portion 41 to which the toner cartridge 2 is mounted will be described.

[0050] like Figure 2 As shown, the loading sections 41 are modules into which toner cartridges 2 filled with toner are mounted. Each of the multiple loading sections 41 includes a space for mounting the toner cartridges 2 and a toner replenishing motor 61. Furthermore, each of the multiple loading sections 41 includes a communication interface (not shown) that connects the IC chip of the toner cartridge 2 to the system controller 13.

[0051] The toner supply motor 61 drives the toner delivery mechanism 52 of the toner cartridge 2 under the control of the processor 21. When the toner cartridge 2 is loaded into the loading portion 41, the toner supply motor 61 is connected to the toner delivery mechanism 52 of the toner cartridge 2. When energized, the toner supply motor 61 rotates its shaft under the control of the processor 21, thereby driving the toner delivery mechanism 52 of the toner cartridge 2. By driving the toner delivery mechanism 52, the toner supply motor 61 supplies the toner in the toner container 51 to the developing device (described later).

[0052] Next, the processing unit 42 will be described.

[0053] The processing units 42 are structures that form toner images. For example, multiple processing units 42 are provided for each toner. For example, multiple processing units 42 correspond to color toners such as cyan, magenta, yellow, and black. Specifically, each processing unit 42 is connected to a toner cartridge 2 containing a different color toner.

[0054] like Figure 2 As shown, the process unit 42 includes a photosensitive drum 71 , a cleaner 72 , a charger 73 , and a developer 74 .

[0055] The photosensitive drum 71 is a photosensitive body including a cylindrical drum and a photosensitive layer formed on the outer peripheral surface of the drum. The photosensitive drum 71 is rotated at a constant speed by a driving mechanism (not shown).

[0056] The cleaner 72 removes toner remaining on the surface of the photoconductive drum 71 .

[0057] The charger 73 uniformly charges the surface of the photosensitive drum 71. For example, the charger 73 applies a voltage to the photosensitive drum 71 using a charging roller, thereby charging the photosensitive drum 71 to a uniform negative potential. The charging roller rotates as the photosensitive drum 71 rotates while applying a predetermined pressure to the photosensitive drum 71.

[0058] The developing device 74 is a device that causes toner to adhere to the photosensitive drum 71. The developing device 74 includes a developer container 81, a stirring mechanism 82, a developing roller 83, a doctor blade 84, an automatic toner control (ATC) sensor 85, and the like.

[0059] The developer container 81 is a container for storing developer including toner and carrier. The developer container 81 receives the toner fed from the toner cartridge 2 by the toner feeding mechanism 52. The carrier is stored in the developer container 81 when the developing device 74 is manufactured.

[0060] The stirring mechanism 82 is driven by a motor (not shown) to stir the toner and the carrier in the developer container 81 .

[0061] The developing roller 83 rotates in the developer container 81 , thereby causing the developer to adhere to the surface.

[0062] The scraper 84 is disposed at a predetermined distance from the surface of the developing roller 83. The scraper 84 removes a portion of the developer adhering to the surface of the rotating developing roller 83. This forms a layer of developer on the surface of the developing roller 83 having a thickness corresponding to the distance between the scraper 84 and the surface of the developing roller 83.

[0063] The ATC sensor 85 is, for example, a magnetic flux sensor having a coil and detecting a voltage generated in the coil. The detection voltage of the ATC sensor 85 changes depending on the density of the magnetic flux from the toner in the developer container 81. Specifically, the system controller 13 can determine the concentration ratio (abbreviated as "concentration") of the toner remaining in the developer container 81 relative to the carrier based on the detection voltage of the ATC sensor 85.

[0064] Next, the exposure device 43 will be described.

[0065] The exposure device 43 includes multiple light-emitting elements. The exposure device 43 irradiates light from the light-emitting elements onto the charged photosensitive drum 71, thereby forming a latent image on the photosensitive drum 71. The light-emitting elements are, for example, light-emitting diodes (LEDs) or laser diodes (LDs). Each light-emitting element is configured to irradiate light at a single point on the photosensitive drum 71. The multiple light-emitting elements are arranged in a direction parallel to the rotation axis of the photosensitive drum 71, i.e., in the main scanning direction.

[0066] The exposure device 43 irradiates light onto the photosensitive drum 71 using a plurality of light emitting elements arranged in the main scanning direction, thereby forming a latent image corresponding to one line on the photosensitive drum 71. Furthermore, the exposure device 43 forms a latent image corresponding to multiple lines by continuously irradiating light onto the rotating photosensitive drum 71.

[0067] In the above-described structure, when light is irradiated from the exposure device 43 onto the surface of the photosensitive drum 71, which has been charged by the charger 73, an electrostatic latent image is formed. When the layer of developer formed on the surface of the developing roller 83 approaches the surface of the photosensitive drum 71, the toner contained in the developer adheres to the latent image formed on the surface of the photosensitive drum 71. As a result, a toner image is formed on the surface of the photosensitive drum 71.

[0068] Next, the transfer mechanism 44 will be described.

[0069] The transfer mechanism 44 is configured to transfer the toner image formed on the surface of the photosensitive drum 71 to the printing medium P.

[0070] like Figure 1 as well as Figure 2 As shown, the transfer mechanism 44 includes, for example, a primary transfer belt 91 , a secondary transfer opposing roller 92 , a plurality of primary transfer rollers 93 , and a secondary transfer roller 94 .

[0071] The primary transfer belt 91 is an endless belt wound around a secondary transfer counter roller 92 and a plurality of winding rollers. The inner surface (inner circumference) of the primary transfer belt 91 contacts the secondary transfer counter roller 92 and the plurality of winding rollers, while the outer surface (outer circumference) faces the photosensitive drum 71 of the process unit 42.

[0072] The secondary transfer opposing roller 92 is rotated by a motor (not shown). The secondary transfer opposing roller 92 rotates to convey the primary transfer belt 91 in a predetermined conveying direction. The plurality of winding rollers are configured to be freely rotatable. The plurality of winding rollers rotate as the primary transfer belt 91 is conveyed by the secondary transfer opposing roller 92.

[0073] The plurality of primary transfer rollers 93 are configured to bring the primary transfer belt 91 into contact with the photosensitive drums 71 of the process units 42. The primary transfer rollers 93 are positioned to correspond to the photosensitive drums 71 of the process units 42. Specifically, the primary transfer rollers 93 are positioned to face the photosensitive drums 71 of the corresponding process units 42, with the primary transfer belt 91 interposed therebetween. The primary transfer rollers 93 contact the inner circumference of the primary transfer belt 91, displacing the primary transfer belt 91 toward the photosensitive drums 71. This causes the primary transfer rollers 93 to bring the outer circumference of the primary transfer belt 91 into contact with the photosensitive drums 71.

[0074] The secondary transfer roller 94 is positioned opposite the primary transfer belt 91. The secondary transfer roller 94 contacts and applies pressure to the outer circumference of the primary transfer belt 91. This forms a transfer nip where the secondary transfer roller 94 and the outer circumference of the primary transfer belt 91 are in close contact. When the print medium P passes through the transfer nip, the secondary transfer roller 94 presses the print medium P passing through the transfer nip against the outer circumference of the primary transfer belt 91.

[0075] The secondary transfer roller 94 and the secondary transfer opposing roller 92 rotate to sandwich and convey the print medium P supplied from the paper feed conveyance path 31. As a result, the print medium P passes through the transfer nip.

[0076] In the above structure, when the outer peripheral surface of the primary transfer belt 91 contacts the photosensitive drum 71, the toner image formed on the surface of the photosensitive drum is transferred to the outer peripheral surface of the primary transfer belt 91. Figure 1 As shown, when the image forming unit 19 includes multiple process units 42, the primary transfer belt 91 receives toner images from the photosensitive drums 71 of the multiple process units 42. The toner image transferred to the outer peripheral surface of the primary transfer belt 91 is conveyed by the primary transfer belt 91 to a transfer nip where a secondary transfer roller 94 is in close contact with the outer peripheral surface of the primary transfer belt 91. When a print medium P is present in the transfer nip, the toner image transferred to the outer peripheral surface of the primary transfer belt 91 is transferred to the print medium P in the transfer nip.

[0077] Next, the configuration related to fixing of the image forming apparatus 1 will be described.

[0078] The fuser 20 fuses the toner transferred to the print medium P, thereby fixing the toner image. The fuser 20 operates under the control of the system controller 13. The fuser 20 includes a heating member for applying heat to the print medium P and a pressure member for applying pressure to the print medium P. For example, the heating member is a heating roller 95. Furthermore, for example, the pressure member is a pressure roller 96.

[0079] The heating roller 95 is a fixing rotating body rotated by a motor (not shown). The heating roller 95 comprises a hollow metal core and an elastic layer formed on the outer circumference of the core. The heating roller 95 is heated to a high temperature by a heater located inside the hollow core. The heater is, for example, a halogen heater. Alternatively, the heater may be an induction heating (IH) heater that heats the core through electromagnetic induction.

[0080] The pressure roller 96 is positioned opposite the heating roller 95. The pressure roller 96 includes a core rod formed of metal with a predetermined outer diameter and an elastic layer formed on the outer periphery of the core rod. The pressure roller 96 applies pressure to the heating roller 95 by applying stress from a tension member (not shown). By applying pressure from the pressure roller 96 to the heating roller 95, a nip (fixing nip) is formed in which the pressure roller 96 and the heating roller 95 are in close contact. The pressure roller 96 is rotated by a motor (not shown). The rotation of the pressure roller 96 moves the print medium P that has entered the fixing nip and presses the print medium P against the heating roller 95.

[0081] According to the above configuration, the heating roller 95 and the pressure roller 96 apply heat and pressure to the print medium P passing through the fixing nip. This fixes the toner image to the print medium P that has passed through the fixing nip. The print medium P that has passed through the fixing nip is guided into the paper discharge conveyor 32 and discharged outside the housing 11. The fixing unit 20 is not limited to the above configuration. The fixing unit 20 may also be configured in an on-demand manner such that heat is applied to the print medium P to which the toner image has been transferred via a film-like member, causing the toner to melt and fix.

[0082] Next, control of the image forming apparatus 1 by the system controller 13 will be described.

[0083] Figure 3 This is a flowchart for explaining the processing related to toner by the system controller 13. The processor 21 of the system controller 13 executes Figure 3 For example, the processor 21 may be configured to execute the process each time a sheet of printing is executed. Figure 3 The processing can also be configured to be executed every time a printing job is completed. Figure 3 The processing can also be configured to be executed every time multiple printing is executed. Figure 3 processing.

[0084] The processor 21 accumulates the number of pixels (pixel count value) based on the pixel values of the image data for printing (ACT 11). For example, the processor 21 accumulates the pixel count value based on the pixel values of the image data for printing. Specifically, the processor 21 converts the image data into an image signal for driving each exposure device 43. Based on the image signal, the processor 21 accumulates the pixel count value for each color of the toner after the toner cartridge 2 is replaced. The processor 21 stores the pixel count value in the memory 22, for example. By accumulating the pixel count value, the processor 21 updates the pixel count value in the memory 22.

[0085] The processor 21 accumulates the driving amount (driving time) of the toner supply motor 61 after the toner cartridge 2 is replaced (ACT 12). The processor 21 stores the driving time in the memory 22. The processor 21 updates the driving time in the memory 22 by accumulating the driving time.

[0086] The processor 21 calculates the remaining toner amount indicating the remaining toner amount in the toner storage container 51 of the toner cartridge 2 (ACT 13). The processor 21 stores the calculated remaining toner amount in, for example, the memory 22. The processor 21 calculates the remaining toner amount based on, for example, the accumulated value of the driving time.

[0087] The processor 21 calculates the toner supply amount based on, for example, the accumulated value of the drive time. The toner supply amount is the ratio of the amount of toner supplied from the toner cartridge 2 to the developer 74 to the initial value of the toner amount within the toner container 51 of the toner cartridge 2. The initial value of the remaining toner amount in the memory 22 is 100%. The processor 21 updates the remaining toner amount in the memory 22 based on the calculated toner supply amount and the remaining toner amount in the memory.

[0088] Specifically, the processor 21 calculates the rotation amount based on the rotation speed (rotation amount) of the toner supply motor 61 shaft per unit drive time and the cumulative value of the toner supply motor 61 drive time. Based on the calculated rotation amount and the toner supply amount per unit rotation amount, the processor 21 calculates the toner supply amount [%] corresponding to the cumulative value of the drive time. The processor 21 calculates the current toner remaining amount [%] in the toner cartridge 2 by subtracting the calculated toner supply amount [%] from the initial value of 100 [%].

[0089] In addition, the rotation speed (rotation amount) of the colorant supply motor 61 shaft per unit driving time and the colorant supply amount per unit rotation amount are predetermined in consideration of the average value of the evaluation results of each model of the image forming apparatus 1 and the colorant cartridge 2, and the deviation between image forming apparatuses 1.

[0090] The processor 21 causes the display unit 14 to display the remaining toner amount on the memory 22 (ACT 14 ). The processor 21 may be configured to cause the display unit 14 to display the remaining toner amount based on an operation input, or may be configured to notify other devices of the remaining toner amount via the communication interface 12 .

[0091] The processor 21 performs a toner replenishment process (ACT 15 ) described later. In the toner replenishment process, the processor 21 determines whether toner replenishment is necessary, detects toner exhaustion, and drives the toner replenishment motor 61 .

[0092] The processor 21 determines whether the calculated remaining toner amount is equal to or greater than a preset near-end threshold (ACT 16 ). If the processor 21 determines that the calculated remaining toner amount is equal to or greater than the preset near-end threshold (ACT 16 , Yes), the process proceeds to ACT 22 described below.

[0093] When the processor 21 determines that the calculated remaining toner amount is less than a preset near-end threshold value (ACT 16 , No), it detects near-end (ACT 17 ). Near-end indicates that little toner remains in the toner cartridge 2 .

[0094] When the processor 21 detects that the toner cartridge is nearly empty, the processor 21 outputs a message urging replacement of the toner cartridge (displaying that the toner cartridge is nearly empty) through the display unit 14 (ACT 18 ).

[0095] The processor 21 performs a toner replenishment rate calculation process (ACT 19 ) described later. In the toner replenishment rate calculation process, the processor 21 calculates the toner replenishment rate and detects toner end.

[0096] Next, the processor 21 determines whether toner exhaustion has been confirmed (ACT 20). The processor 21 determines whether toner exhaustion has been confirmed based on the toner exhaustion detection results of the toner replenishment process and the toner exhaustion detection results of the toner replenishment rate calculation process. For example, if toner exhaustion is detected in either the toner replenishment process or the toner replenishment rate calculation process, the processor 21 determines that toner exhaustion has been confirmed.

[0097] When the processor 21 determines that the toner is not yet exhausted (ACT 20 , No), the process proceeds to ACT 22 .

[0098] When the processor 21 determines that the toner is exhausted (ACT 20 , YES), the processor 21 outputs a message (toner exhaustion display) urging replacement of the toner cartridge 2 via the display unit 14 (ACT 21 ), and proceeds to ACT 22 .

[0099] The processor 21 determines whether to end the processing (ACT22). For example, when the processor 21 performs an operation to end the action of the image forming device 1 or when there is no subsequent printing, the processor 21 determines that the processing is to be ended. When there is subsequent printing and the processor 21 determines that the processing is not to be ended (ACT22, No), the processor 21 transfers to the processing of ACT11. Thus, each time printing is executed, the processor 21 repeatedly executes the processing of ACT11 to ACT22. In addition, when the processor 21 determines that the processing is to be ended (ACT22, Yes), the processor 21 ends the processing. Figure 3 processing.

[0100] Next, the toner replenishment process will be described.

[0101] Figure 4 : is a flowchart for explaining the toner supply process. Figure 4 The processing is equivalent to Figure 3 Processing of ACT15.

[0102] The processor 21 obtains the toner concentration based on the detection result of the ATC sensor 85 (ACT 31). The detection voltage of the ATC sensor 85 changes according to the density of the magnetic flux from the toner in the developer container 81. The processor 21 calculates the toner concentration relative to the carrier in the developer container 81 based on the detection voltage of the ATC sensor 85 and a predetermined coefficient or function.

[0103] Processor 21 compares the toner concentration [%] with a preset reference concentration [%] (step S32). The reference concentration is the toner concentration required for stable operation of developer 74 and is pre-stored in memory 22, for example. For example, processor 21 calculates the difference between the toner concentration obtained in ACT 31 and the reference concentration.

[0104] The processor 21 determines whether the toner concentration has decreased by 1.0% or more (ACT 33). In other words, the processor 21 determines whether the toner concentration minus the reference concentration is equal to or greater than -1.0%. In other words, the processor 21 determines whether the toner concentration in the developer container 81 is equal to or greater than a predetermined threshold.

[0105] When the processor 21 determines that the amount of reduction in the toner concentration is not greater than 1.0% (ACT 33, No), the process ends. Figure 4 processing.

[0106] When the processor 21 determines that the toner concentration has decreased by 1.0% or more (ACT 33 , YES), it determines whether the toner replenishment operation has continued for a predetermined time or longer (ACT 34 ). Specifically, the processor 21 determines whether the toner replenishment motor 61 is being driven and whether the toner replenishment motor 61 has been driven for a predetermined time or longer.

[0107] If the processor 21 determines that the toner replenishment operation has not continued for a predetermined time or longer (ACT 34, NO), it performs a toner replenishment operation (ACT 35) and proceeds to the processing of ACT 31. Specifically, the processor 21 drives the toner replenishment motor 61 to replenish toner from the toner cartridge 2 to the developer 91. The processor 21 continues the toner replenishment operation until, for example, the amount of toner concentration reduction becomes less than 1.0% or until a predetermined time has elapsed.

[0108] When the processor 21 determines that the toner replenishing operation has continued for a predetermined time or longer (ACT 34 , YES), it determines whether the toner concentration has decreased by 1.5% or more (ACT 36 ). Specifically, the processor 21 determines whether the toner concentration minus the reference concentration is equal to or greater than -1.5%.

[0109] When the processor 21 determines that the amount of decrease in the toner concentration is not greater than 1.5% (ACT 36, No), the process ends. Figure 4 processing.

[0110] When the processor 21 determines that the amount of decrease in the toner concentration is 1.5% or more (ACT 36, YES), it detects that the toner is exhausted (ACT 37), and ends the process. Figure 4 That is, the processor 21 detects that the toner is exhausted when the toner concentration does not recover even after the toner replenishment operation is performed for a predetermined time.

[0111] Next, the toner replenishment rate calculation process will be described.

[0112] Figure 5 1 is a flowchart for explaining the toner replenishment rate calculation process. Figure 5 The processing is equivalent to Figure 3 Processing of ACT19.

[0113] The processor 21 determines whether the interval print count is greater than a preset threshold value (ACT 41). The interval print count indicates the number of printed documents. Whenever the interval print count exceeds the threshold value, the processor 21 resets the interval print count.

[0114] When the processor 21 determines that the number of printed sheets in the interval is less than the preset threshold value (ACT 41, No), the process ends. Figure 5 processing.

[0115] When the processor 21 determines that the number of printed sheets per section is equal to or greater than a preset threshold value (ACT 41 , YES), the processor 21 resets the number of printed sheets per section and executes the processes of ACT 42 to ACT 44 described later.

[0116] When the processor 21 determines that the number of printed sheets in the interval is greater than a preset threshold (ACT 41 , YES), it calculates the toner replenishment rate during printing for the number of printed sheets in the interval (ACT 42 ). Specifically, the processor 21 calculates the toner replenishment rate each time the number of printed sheets in the interval reaches the preset threshold.

[0117] The toner replenishment rate is the ratio of the toner usage to the toner supply amount during the period from when the number of printed sheets in the interval is reset to when the threshold is reached (hereinafter referred to as the replenishment rate calculation interval). The toner usage can be estimated based on the pixel count value. The toner supply amount can be estimated based on the drive time of the toner supply motor 61. The processor 21 calculates the toner replenishment rate based on the cumulative value of the pixel count value and the cumulative value of the drive time of the toner supply motor 61. For example, the processor 21 calculates the toner replenishment rate based on the increase in the cumulative value of the pixel count value in the replenishment rate calculation interval and the increase in the cumulative value of the drive time of the toner supply motor 61 in the replenishment rate calculation interval. More specifically, the processor 21 calculates the toner replenishment rate as the value obtained by dividing the normalized value of the cumulative value of the pixel count value by the normalized value of the increase in the cumulative value of the drive time of the toner supply motor 61. That is, the toner replenishment rate is a ratio of the pixel count value to the driving time of the toner replenishment motor 61 .

[0118] The processor 21 determines whether the calculated toner replenishment rate is equal to or less than a preset toner replenishment rate threshold (ACT 43). The toner replenishment rate threshold is predetermined by taking into account the average value of the evaluation results for each model of the image forming apparatus 1 and the toner cartridge 2, as well as variations between image forming apparatuses 1. The toner replenishment rate threshold is pre-stored in the memory 22, for example.

[0119] When the processor 21 determines that the toner replenishment rate is not less than the toner replenishment rate threshold (ACT 43, No), the process ends. Figure 5 processing.

[0120] When the processor 21 determines that the toner replenishment rate is less than the toner replenishment rate threshold (ACT 43, YES), it detects that the toner is exhausted (ACT 44), and ends the process. Figure 5 That is, when the driving time of the toner replenishment motor 61 becomes longer relative to the pixel count value and the toner replenishment rate becomes less than the toner replenishment rate threshold, the processor 21 detects that the toner is empty.

[0121] Figure 6 This is a diagram illustrating the relationship among the toner replenishment rate, the number of printed sheets, and the printing rate. Figure 6 The vertical axis represents the toner replenishment rate. Figure 6 The horizontal axis represents the number of printed sheets. Figure 6 The curves in FIG. 1 represent different printing rates. Figure 6 The relationship between the number of printed sheets and the toner replenishment rate before and after the time when the toner cartridge 2 is substantially empty (number of printed sheets = 0) is shown. Figure 6 In the example of , the toner replenishment rate threshold is set to 100.

[0122] like Figure 6 As shown, the toner replenishment rate decreases in proportion to the number of printed sheets. In other words, the toner replenishment rate decreases in proportion to the amount of toner in the toner cartridge 2. This is because as the amount of toner in the toner cartridge 2 decreases, the amount of toner supplied per unit drive of the toner cartridge 2's delivery mechanism 52 decreases, and the drive time of the toner replenishment motor 61 required to supply the same amount of toner increases.

[0123] Furthermore, the degree of reduction in the toner replenishment rate varies depending on the printing rate. Specifically, the higher the printing rate, the greater the reduction in the toner replenishment rate per unit number of printed sheets, and the lower the printing rate, the smaller the reduction in the toner replenishment rate per unit number of printed sheets. Therefore, for example, if the printing rate of the printed image is 10% or less, the toner replenishment rate threshold value will be lowered after 100 sheets are printed from a state where there is substantially no toner. Alternatively, for example, if the printing rate of the printed image is 1% or less, the toner replenishment rate threshold value will not be lowered after 100 sheets are printed from a state where there is substantially no toner, and the toner replenishment rate threshold value will be lowered after 150 sheets are printed. Alternatively, for example, if the printing rate of the printed image is 20% or more, toner exhaustion is detected based on the toner concentration before the toner replenishment rate threshold value is reached.

[0124] Figure 7 This is an explanatory diagram for explaining the relationship between a toner replenishment rate method for detecting toner end based on the toner replenishment rate and a toner concentration sensor detection method for detecting toner end based on the toner concentration. Figure 7 The vertical axis represents the number of printed sheets from the state where there is substantially no toner until the toner exhaustion is detected. Figure 7 The horizontal axis represents the printing rate.

[0125] like Figure 7 As shown, in the toner concentration sensor detection method, at low printing rates, the number of printed sheets until toner end detection tends to increase. This is because at low printing rates, it takes time for the toner concentration in the developer container 81 to decrease after toner supply from the toner cartridge 2 stops.

[0126] In contrast, the toner replenishment rate method tends to show a stable number of printed sheets until toner end is detected, regardless of the printing rate. This is because, regardless of the state of the developer container 81, when the developer container 81 is substantially empty of toner, the cumulative drive time of the toner replenishment motor 61 increases relative to the cumulative pixel count, significantly reducing the toner replenishment rate. In other words, at low printing rates, where toner end detection is delayed, the toner concentration sensor detection method can detect toner end earlier than the toner concentration sensor detection method.

[0127] As in Figure 3 As described in ACT 20 of FIG. 1 , the processor 21 determines that the toner is exhausted when it detects that the toner is exhausted by any one of the toner concentration sensor detection method and the toner replenishment rate method. Figure 7 In the example of printing rate = less than 10 [%]), the toner exhaustion detection based on the toner supply rate method is used. At high printing rate ( Figure 7 In the example of FIG, the printing rate = 10 [%] or more), the toner end detection method based on the toner concentration sensor is adopted.

[0128] As described above, the image forming apparatus 1 includes: a photosensitive drum 71; an exposure device 43 for exposing the photosensitive drum 71 based on image data; a developer 74 for forming a toner image on the photosensitive drum 71 using toner supplied from the toner cartridge 2; a toner supply motor 61 for supplying toner from the toner cartridge 2 to the developer 74; and a processor 21. The processor 21 calculates a toner supply rate based on the accumulated pixel count values of the image data and the accumulated drive time of the toner supply motor. The processor 21 detects toner exhaustion when the toner supply rate falls below a preset threshold.

[0129] Thus, the image forming apparatus 1 can prevent the number of printed sheets from being detected as near-toner end until toner end is detected from being skewed by the print rate of the image data being printed. In particular, the image forming apparatus 1 can prevent an increase in the number of printed sheets until toner end is detected when the print rate of the image data being printed is low. As a result, the developer 74 operates for an extended period of time while the toner concentration in the developer container 81 of the developer 74 is low, thereby preventing a load on the developer 74.

[0130] Furthermore, in the above embodiment, the processor 21 calculates the value obtained by dividing the cumulative value of the pixel count by the cumulative value of the drive time of the toner replenishment motor 61 as the toner replenishment rate. However, the present invention is not limited to this configuration. The processor 21 may also calculate the value obtained by dividing the cumulative value of the drive time of the toner replenishment motor 61 by the cumulative value of the pixel count as the toner replenishment rate.

[0131] In addition, in the above embodiment, it is described that each time a number of sheets preset as the interval printing number is printed, the processor 21 calculates the cumulative value of the pixel count value and the cumulative value of the driving time of the colorant supply motor 61, but it is not limited to this structure. The processor 21 may have any structure as long as it calculates the cumulative value of the pixel count value and the cumulative value of the driving time of the colorant supply motor 61 in units of a preset processing interval. For example, the processing interval may be determined based on the cumulative value of the pixel count value or the cumulative value of the driving time of the colorant supply motor 61. That is, Figure 5 ACT 41 may be replaced by a determination of “whether the integrated value of the pixel count value has increased by a preset value” or “whether the integrated value of the driving time of the toner replenishing motor 61 has increased by a preset value”.

[0132] For example, when the processing interval is determined based on the cumulative value of the pixel count, the processor 21 calculates the amount of increase in the cumulative value of the drive time of the toner replenishment motor 61 each time the cumulative value of the pixel count increases by a predetermined value. In other words, the processor 21 calculates the toner replenishment rate based on the amount of increase in the cumulative value of the drive time of the toner replenishment motor 61 during the period in which the cumulative value of the pixel count increases by the predetermined value.

[0133] Furthermore, for example, when the processing interval is determined based on the cumulative value of the drive time of the toner replenishment motor 61, the processor 21 calculates the amount of increase in the cumulative value of the pixel count value each time the cumulative value of the drive time of the toner replenishment motor 61 increases by a predetermined value. In other words, the processor 21 calculates the toner replenishment rate based on the amount of increase in the cumulative value of the pixel count value during the period in which the cumulative value of the drive time of the toner replenishment motor 61 increases by the predetermined value.

[0134] Furthermore, in the above embodiment, the remaining amount of toner in the toner container 51 of the toner cartridge 2 is calculated based on the cumulative value of the drive time of the toner replenishing motor 61 after the toner cartridge 2 is replaced. However, the present invention is not limited to this configuration. The processor 21 may also be configured to calculate the remaining amount of toner in the toner container 51 of the toner cartridge 2 based on the cumulative value of the pixel count value after the toner cartridge 2 is replaced.

[0135] Furthermore, in the above embodiment, the processor 21 detects near-end of toner based on the remaining toner amount calculated based on the accumulated drive time of the toner replenishment motor 61 and the near-end threshold value. However, the present invention is not limited to this configuration. The processor 21 may also detect near-end of toner based on the replenishment rate.

[0136] For example, the processor 21 calculates the toner replenishment rate per print interval (predetermined processing interval), independent of the toner near-end detection based on the remaining toner level. The processor 21 detects that the toner is near-end when the calculated toner replenishment rate is less than a predetermined threshold (a near-end threshold value compared to the toner replenishment rate). Furthermore, the processor 21 detects that the toner is near-end when the calculated toner replenishment rate is less than a predetermined threshold value (the aforementioned toner replenishment rate threshold value).

[0137] Furthermore, the functions described in the above embodiments are not limited to being configured using hardware, but may be implemented using software by having a computer read a program describing each function. Furthermore, each function may be configured using either software or hardware as appropriate.

[0138] Although several embodiments have been described, these embodiments are provided for illustrative purposes only and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways and can be omitted, replaced, or modified without departing from the spirit of the invention. These embodiments and their variations are intended to be included within the scope and spirit of the invention and are also intended to be included within the scope of the invention set forth in the claims and their equivalents.

Claims

1. An image forming apparatus comprising: Photosensitive drum; an exposure device for exposing the photosensitive drum based on image data; a developer for forming a toner image on the photosensitive drum using toner supplied from a toner cartridge; a toner supply motor for supplying toner from the toner cartridge to the developer; as well as The processor detects that the toner is exhausted when a toner replenishment rate calculated based on an integrated value of pixel count values of the image data and an integrated value of a driving time of the toner replenishment motor is less than a preset threshold value. The toner replenishment rate is the ratio of the toner usage amount to the toner replenishment amount in the replenishment rate calculation interval. The processor calculates the toner replenishment rate based on an increase in an integrated value of the pixel count value in the replenishment rate calculation interval and an increase in an integrated value of a driving time of the toner replenishment motor in the replenishment rate calculation interval.

2. The image forming apparatus according to claim 1, wherein The processor calculates the toner replenishment rate based on an integrated value of the pixel count value and an integrated value of the driving time of the toner replenishment motor in a predetermined processing section.

3. The image forming apparatus according to claim 2, wherein: The processing interval is determined based on a predetermined number of printed sheets.

4. The image forming apparatus according to claim 2, wherein: The processing interval is a interval determined based on the accumulated value of the pixel count value.

5. The image forming apparatus according to claim 2, wherein: The processing section is a section determined based on the accumulated value of the driving time of the toner replenishing motor.

6. The image forming apparatus according to any one of claims 1 to 5, wherein The processor calculates the toner replenishment rate when detecting that the toner is nearly empty based on the accumulated value of the driving time of the toner replenishment motor.

7. The image forming apparatus according to any one of claims 1 to 5, wherein The image forming apparatus further includes a toner concentration sensor configured to detect a toner concentration in the developer in the developing device. The processor drives the toner supply motor when the toner concentration is less than a preset threshold value. When the toner concentration is not restored by driving the toner supply motor, it is detected that the toner is exhausted. Toner end is determined based on either detection of toner end based on the toner replenishment rate or detection of toner end based on the toner concentration.

8. A method for controlling an image forming apparatus, wherein: The image forming device comprises: a photosensitive drum; an exposure device for exposing the photosensitive drum based on image data; a developer for forming a toner image on the photosensitive drum using toner supplied from a toner cartridge; and a toner supply motor for supplying toner from the toner cartridge to the developer. and the processor, The processor detects toner exhaustion when a toner replenishment rate calculated based on an integrated value of pixel count values of the image data and an integrated value of a driving time of the toner replenishment motor is less than a preset threshold value. The toner replenishment rate is the ratio of the toner usage amount to the toner replenishment amount in the replenishment rate calculation interval. The processor calculates the toner replenishment rate based on an increase in an integrated value of the pixel count value in the replenishment rate calculation interval and an increase in an integrated value of a driving time of the toner replenishment motor in the replenishment rate calculation interval.

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