Image forming apparatus

Abstract

To reduce a detection error in a system for detecting the amount of developer in a developer container by measuring the number of pixels of an image part.SOLUTION: An image forming apparatus 200 has: an image carrier 201; electrostatic image forming means 202, 204 that form an image part of an electrostatic image on the image carrier 201; a developing device 209 in which developer is supplied to a storage unit 207 from a supply container 223 connected with the storage unity 207; and an acquisition unit 240 that acquires first information on the number of pixels of the image part, and corrects the first information according to second information on the amount of developer supplied from the supply container 223 to the storage unit 207 and acquires the corrected information as third information on the amount of developer in the storage unit 207.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus, such as a copying machine, a printer, or a facsimile machine, that uses an electrophotographic or electrostatic recording method. [Background technology]

[0002] In an image forming apparatus using an electrophotographic method, an electrostatic latent image formed on an image carrier is developed by a developing device that supplies toner as a developer, and a toner image is formed on the image carrier. The toner image formed on the image carrier is transferred to a recording material and then fixed to the recording material. The developing device has, for example, a developing container (frame) that contains toner, and a developing roller that is rotatably arranged at the opening of the developing container and serves as a developing member (developer carrier) that carries the toner and rotates to transport the toner from the inside of the developing container to the outside.

[0003] In such image forming apparatuses, a process cartridge system in which a process cartridge is detachably attached to the main body of the image forming apparatus is widely adopted in order to facilitate the replacement and maintenance of consumables such as an image carrier and toner. A process cartridge is a system in which an image carrier and a process means such as a developing device acting on the image carrier are detachably attached to the main body of the image forming apparatus as a whole. Also adopted is a toner cartridge system in which a toner cartridge containing toner to be replenished to a developing container of a developing device is detachably attached to the process cartridge separately.

[0004] According to the process cartridge system, the user can perform maintenance of the image forming apparatus without relying on a serviceman. According to the toner cartridge system, when the toner runs out, the user can replace only the toner cartridge, thereby reducing the cost and labor involved in replacement. The developing device may be detachably attached to the main body of the image forming apparatus as a part of the process cartridge, or may be detachably attached to the main body of the image forming apparatus as an independent unit.

[0005] Generally, toner is replenished from the toner cartridge to the developing container when a developer remaining amount detection unit detects that the toner in the developing container has decreased to a predetermined amount.

[0006] Patent Document 1 describes a method for obtaining the amount of toner consumption based on the number of pixels of an image to be output. This method for obtaining the amount of toner consumption is generally called a pixel counting method. In the pixel counting method, for example, the amount of toner consumed by image formation is obtained by multiplying the number of pixels of an image portion exposed by a laser on an image carrier by the amount of toner consumed per pixel (unit amount of toner consumption). Then, the amount of toner remaining in the developing container is obtained by subtracting the amount of toner consumed from the amount of toner filled in the developing container.

[0007] Furthermore, Patent Document 2 describes a method of acquiring the amount of consumed toner using a unit toner consumption amount corresponding to the amount of toner remaining in a developing container in a pixel counting method. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2001-242766 A [Patent Document 2] Japanese Patent Application Publication No. 10-239979 Summary of the Invention [Problem to be solved by the invention]

[0009] However, the conventional pixel counting method has the following problems.

[0010] In other words, the conventional pixel counting method does not take into account the effects that occur when toner is replenished from a toner cartridge to a developing device, such as the effects of fogging. Fogging is a phenomenon in which toner adheres to areas other than the image area (non-image area) on the image carrier.

[0011] The following describes an example of the effect of fogging on the pixel counting method when toner is replenished to the developing device. For example, in an image forming apparatus configured to replenish toner from a toner cartridge to a developing container, when toner is replenished from the toner cartridge to the developing container, a toner with a low charge may be coated on the upper layer of the toner coat on the developing roller. This is considered to be due to the difference in lubricity and chargeability between the new toner replenished from the toner cartridge and the toner in the developing container housed in the developing container. This makes fogging more likely to occur, and an error (hereinafter also simply referred to as "detection error") may occur between the detection result of the toner remaining amount by the pixel counting method and the actual remaining amount of toner. If the amount of toner in the developing container decreases due to the accumulation of this detection error, toner deterioration may be accelerated, and streaky image defects may occur.

[0012] The same problem may also occur when reproducing a process cartridge by reusing the developing container of a used process cartridge and refilling it with new toner (hereinafter, also referred to as "recycled production"). Furthermore, the same problem may also occur when toner adheres to the surface of the developing roller due to repeated use of the developing roller.

[0013] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to suppress detection errors in a method for detecting the amount of developer in a developer container by measuring the number of pixels in an image portion. [Means for solving the problem]

[0014] The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention is an image forming apparatus including an image carrier, an electrostatic image forming means for forming an image portion on the image carrier by an electrostatic image, a developing member for supplying a developer to the image portion on the image carrier to form a developer image on the image carrier, and a container for containing the developer to be supplied to the developing member, the developing device being configured to supply developer to the container from a supply container connected to the container, and an acquisition unit for acquiring first information on the number of pixels of the image portion, correcting the first information according to second information on the amount of developer supplied from the supply container to the container, and acquiring third information on the amount of developer in the container.

[0015] According to another aspect of the present invention, there is provided an image forming apparatus comprising: an image carrier; an electrostatic image forming means for forming an image portion on the image carrier using an electrostatic image; a developing device including a developing member for supplying developer to the image portion on the image carrier to form a developer image on the image carrier, and a storage section for storing the developer to be supplied to the developing member; a memory section for storing first information regarding an amount of developer replenished to the storage section of the developing device produced by reusing the storage section; and an acquisition section for acquiring second information regarding the number of pixels of the image portion, and correcting the second information in accordance with the first information stored in the memory section to acquire third information regarding the amount of developer in the storage section.

[0016] According to yet another aspect of the present invention, there is provided an image forming apparatus comprising: an image carrier; an electrostatic image forming means for forming an image portion on the image carrier using an electrostatic image; a developing device including a developing member for supplying developer to the image portion on the image carrier to form a developer image on the image carrier, and a container for containing the developer to be supplied to the developing member; a first acquisition unit for supplying a current or voltage to the developing member to acquire first information regarding an electrical resistance value of the developing member; and a second acquisition unit for acquiring second information regarding the number of pixels of the image portion, correcting the second information according to the first information, and acquiring third information regarding an amount of developer in the container. Effect of the Invention

[0017] According to the present invention, it is possible to suppress detection errors in a method for detecting the amount of developer in a developer container by measuring the number of pixels in an image portion. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic cross-sectional view of an image forming apparatus. [Diagram 2] FIG. 4 is a flowchart of a toner supply operation in the first embodiment. [Diagram 3] FIG. 11 is a graph showing the transition of the fogging level due to toner replenishment. [Figure 4] 11 is a table showing settings of correction coefficients according to amounts of supplied toner. [Diagram 5] FIG. 11 is a graph showing the transition of the fogging level due to toner replenishment. [Figure 6] 11 is a table showing settings of correction coefficients according to amounts of replenished toner. [Figure 7] FIG. 11 is a schematic cross-sectional view of another example of an image forming apparatus. [Figure 8] 4 is a graph showing the change in the electric resistance value (current value) of a developing roller. [Figure 9] FIG. 11 is a graph showing the transition of the fogging level depending on the remaining life of the developing device. [Figure 10] 11 is a table showing settings of correction coefficients according to the electric resistance value (current value) of the developing roller. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

[0020] [Example 1] 1. Image forming device First, the overall configuration of an image forming apparatus 200 of this embodiment will be described with reference to Fig. 1. The image forming apparatus 200 of this embodiment is a monochrome laser beam printer that employs a process cartridge system and a toner cartridge system and is capable of forming a black monochrome image on a sheet-shaped recording material P using an electrophotographic system. Fig. 1 is a schematic cross-sectional view of the image forming apparatus 200 in a state in which a process cartridge 222 and a toner cartridge 223 are attached. The image forming apparatus 200 forms and outputs an image on a recording material P based on image information (image signal) input from an external device such as a personal computer.

[0021] An electrophotographic image forming apparatus is an apparatus that forms an image on a recording material using an electrophotographic image forming process. Examples of image forming apparatuses include copying machines, printers (laser beam printers, LED printers, etc.), facsimile machines, multifunction machines (multifunction printers) that have a plurality of functions, and word processors. A process cartridge is an apparatus that is detachably attached to the main body of an image forming apparatus, and includes an image carrier and at least one of a charging means, a developing means, and a cleaning means as process means acting on the image carrier. A toner cartridge is an apparatus that is detachably attached to the main body of an image forming apparatus, and includes a supply developer container that contains a supply developer to be supplied to a developing container of a developing device. The main body of an image forming apparatus (hereinafter, also simply referred to as the "main body") is the portion of the image forming apparatus excluding the process cartridge and the toner cartridge.

[0022] The image forming apparatus 200 has a photosensitive drum 201, which is a rotatable drum-type (cylindrical) photosensitive body (electrophotographic photosensitive body) serving as an image carrier. When an image forming operation is started, the photosensitive drum 201 is driven to rotate in the direction of the arrow R1 (clockwise direction) in the figure. The surface of the rotating photosensitive drum 201 is uniformly charged to a predetermined potential of a predetermined polarity (negative polarity in this embodiment) by a charging roller 202, which is a roller-type charging member serving as a charging means. During charging, a predetermined charging voltage (charging bias) including a DC voltage component of the same polarity (negative polarity in this embodiment) as the charging polarity of the photosensitive drum 201 is applied to the charging roller 202 by a charging power source (high voltage power source) 271 serving as a charging voltage application means. The surface of the charged photosensitive drum 201 is scanned and exposed according to image information (image signal) by an exposure device (laser scanner) 204 serving as an exposure means, and an electrostatic latent image (electrostatic image) is formed on the photosensitive drum 201. The exposure device 204 irradiates the photosensitive drum 201 with a laser beam emitted from a semiconductor laser 203 to selectively expose the surface of the photosensitive drum 201, thereby forming an electrostatic latent image on the photosensitive drum 201. In this embodiment, the charging roller 202 and the exposure device 204 constitute an electrostatic image forming means for forming an electrostatic image on the photosensitive drum 201.

[0023] The electrostatic latent image formed on the photosensitive drum 201 is developed (visualized) by supplying toner 231 as a developer by a developing device 209 as a developing means, and a toner image (toner image, developer image) is formed on the photosensitive drum 201. During development, a predetermined development voltage (developing bias) including a DC voltage component of the same polarity as the charging polarity of the photosensitive drum 201 (negative polarity in this embodiment) is applied to the developing roller 224 of the developing device 209 by a developing power source (high voltage power source) 255 as a developing voltage application means. In this embodiment, toner charged to the same polarity as the charging polarity of the photosensitive drum 201 (negative polarity in this embodiment) is attached to the exposed portion (image portion) on the photosensitive drum 201, the absolute value of the potential of which has been reduced by being exposed after being uniformly charged (reverse development method). In this embodiment, the normal charging polarity (normal polarity) of the toner, which is the main charging polarity of the toner during development, is negative polarity.

[0024] A transfer roller 208, which is a roller-type transfer member serving as a transfer means, is disposed opposite the photosensitive drum 201. The transfer roller 208 is pressed against the photosensitive drum 201 to form a transfer portion Nt, which is a contact portion between the photosensitive drum 201 and the transfer roller 208. The toner image formed on the photosensitive drum 201 is transferred to a recording material (recording medium, transfer material, sheet) P, which is sandwiched and conveyed between the photosensitive drum 201 and the transfer roller 208, at the transfer portion Nt. During transfer, a transfer voltage (transfer bias), which is a DC voltage of the opposite polarity to the normal charging polarity of the toner, is applied to the transfer roller 208 by a transfer power source (high voltage power source) 272 serving as a transfer voltage application means. The recording material P, such as recording paper or a plastic sheet, is stored in a cassette 261 serving as a recording material storage portion, and is sent out one by one from the cassette 261 by a feed roller 262 serving as a feed member. This recording material P is transported to the transfer portion Nt by a transport roller 210 as a transport member in synchronization with the toner image on the photosensitive drum 201.

[0025] The recording material P onto which the toner image has been transferred is transported to a fixing device 219 as a fixing means. The fixing device 219 heats and pressurizes the toner to fix (fuse) it onto the recording material P in the process of nipping and transporting the recording material P carrying the unfixed toner image between a pair of fixing rotors. The fixing device 219 is provided with a temperature thermistor 225 for controlling the fixing temperature of the fixing device 219. The recording material P onto which the toner image has been fixed is transported by a discharge roller 211 as a transport member and is discharged (output) onto a discharge tray 217 as a discharge section provided at the top of the device main body 220.

[0026] In this embodiment, the toner remaining on the photosensitive drum 201 after transfer (transfer residual toner) is charged by the charging roller 202 and then collected by the developing device 209. However, this is not limited to this, and the image forming apparatus 200 may have a cleaning device as a dedicated cleaning means for removing and collecting the transfer residual toner from the photosensitive drum 201. The cleaning device may be configured to have a cleaning blade as a cleaning member arranged in contact with the photosensitive drum 201, a cleaning container that contains the toner removed from the photosensitive drum 201 by the cleaning blade, and the like.

[0027] The image forming apparatus 200 also has a top sensor 214 for synchronizing the conveyance of the recording material P with the formation of a toner image on the photosensitive drum 201. The image forming apparatus 200 also has a discharge sensor 215 for detecting the presence or absence of the recording material P after passing through the fixing device 219. The image forming apparatus 200 also has an engine controller 212 as a control unit for controlling each unit of the image forming apparatus 200 as described above. The engine controller 212 is configured with a CPU 213 as a calculation processing means which is a central element for performing calculation processing, a main body storage unit 216 such as a ROM, RAM, and non-volatile memory as a storage means (storage medium), an input / output circuit (not shown), and the like. The ROM stores a control program, a data table obtained in advance, and the like. The RAM stores information input to the engine controller 212, detected information, calculation results, and the like. The input / output circuit inputs and outputs signals between the engine controller 212 and devices connected thereto. Further, the image forming apparatus 200 is provided with a display unit 250 for displaying the state of the image forming apparatus 200, such as the amount of toner remaining in the developing device 209 and the amount of toner remaining in the toner cartridge 223, and the like.

[0028] In this embodiment, the image forming apparatus 200 has a process cartridge 222 that is detachably attached to the apparatus main body 220. The process cartridge 222 is easily detachably attached to the apparatus main body 220 via attachment means such as an attachment guide and a positioning member provided on the apparatus main body 220 and the process cartridge 222. In this embodiment, the process cartridge 222 has a photosensitive drum 201, a charging roller 202, and a developing device 209. In this embodiment, the process cartridge 222 is provided with a non-volatile memory 230 as a storage means (storage medium) for storing information. The CPU 213 of the engine controller 212 can read and write information from and to the non-volatile memory 230 of the process cartridge 222 attached to the apparatus main body 220.

[0029] In this embodiment, the developing device 209 has a developing container (developing frame) 207 as a container that contains toner 231 as a developer. In this embodiment, the developing device 209 has a developing roller 224 as a developing member (developer carrier) that carries the toner 231 in the developing container 207 and transports it to a portion facing (contacting) the photosensitive drum 201. In this embodiment, the developing device 209 has a conductive developing blade 305 as a regulating member that regulates the amount of toner (layer thickness of the toner coat) on the developing roller 224. In this embodiment, the developing device 209 has a supply roller 228 with a sponge-like elastic layer as a supply member that scrapes off the toner 231 on the developing roller 224 and supplies the toner 231 in the developing container 207 onto the developing roller 224. In this embodiment, the developing device 209 has a transport member 227 that agitates the toner 231 in the developing container 207 and transports it toward the supply roller 228. The developing roller 224, the supply roller 228, and the transport member 227 are rotatably supported in the developing container 207. The developing blade 305 is also supported in the developing container 207. In this embodiment, the developing container 207 contains a non-magnetic one-component developer (toner) as a developer.

[0030] In this embodiment, the developing roller 224 is disposed in contact with the photosensitive drum 201, and is driven to rotate in the direction of the arrow R2 (counterclockwise direction) in the figure. Also, in this embodiment, the supply roller 228 is disposed in contact with the developing roller 224, and is driven to rotate in the direction of the arrow R3 (counterclockwise direction) in the figure. Also, in this embodiment, the transport member 231 is configured to include a shaft member and a sheet member attached to the shaft member, and is driven to rotate in the direction of the arrow R4 (clockwise direction) in the figure. Also, in this embodiment, the developing blade 305 is disposed in contact with the developing roller 224.

[0031] The photosensitive drum 201, the developing roller 224, the supply roller 228, and the transport member 227 are rotated by a driving force transmitted from a driving motor (not shown) serving as a driving source constituting a driving means provided in the main body 220 of the apparatus. The charging roller 202 is disposed in contact with the photosensitive drum 201, and is rotated in accordance with the rotation of the photosensitive drum 201. A developing voltage (developing bias) and a regulating voltage (regulating bias) are applied to the developing roller 224 and the developing blade 305 by a developing power source 255 provided in the main body 220 of the apparatus. A charging voltage (charging bias) is applied to the charging roller 202 from a charging power source (not shown) provided in the main body 220 of the apparatus.

[0032] In the present embodiment, the image forming apparatus 200 has a toner cartridge 223 that is detachably attached to the apparatus main body 220. The apparatus main body 220, the process cartridge 222, and the toner cartridge 223 are provided with attachment means such as an attachment guide and a positioning member. The toner cartridge 223 is easily detachably attached to the apparatus main body 220 and the process cartridge 222 (developing device 209) via the attachment means. The toner cartridge 223 has a supply developer storage section 280 and a supply path 226 that is connected to a supply port 270 provided in the developing container 207 of the developing device 209. The supply developer storage section 280 of the toner cartridge 223 contains, as a supply developer (supply toner), a toner 232 that is the same as the toner 231 contained in the developing container 207 of the developing device 209. The inside of the supply developer storage section 280 and the inside of the developing container 207 are in communication with each other via the supply path 226 and the supply port 270.

[0033] A conveying screw 229 constituting a supply device as a supplying means is provided in the supply path 226. The conveying screw 229 rotates by a driving force transmitted from a driving motor (not shown) constituting a driving means provided in the apparatus main body 220. When the toner 231 in the developing container 207 decreases to a predetermined amount, the conveying screw 229 is driven to rotate, so that the toner 232 in the toner cartridge 223 is replenished into the developing container 207 through the supply path 226. In addition, the toner cartridge 223 is provided with a supply toner remaining amount detection device 234 as a supply developer remaining amount detection means that detects the remaining amount of toner in the toner cartridge 223. In this embodiment, the supply toner remaining amount detection device 234 detects the remaining amount (presence or absence in this embodiment) of the toner 232 in the toner cartridge 223 by accumulating the number of rotations of the conveying screw 229. Then, when the number of rotations of the conveying screw 229 reaches a predetermined threshold, the supply toner remaining amount detection device 234 determines that the remaining amount of toner in the toner cartridge 223 has decreased to a predetermined amount (effectively zero in this embodiment). Then, the supply toner remaining amount detection device 234 notifies the CPU 213 of the engine controller 212 that the remaining amount of toner in the toner cartridge 223 has decreased to the predetermined amount. Note that the supply toner remaining amount detection device 234 can detect the remaining amount of toner in the toner cartridge 223 based on an index value that correlates with the drive amount of the conveying screw 229, such as the rotation time (drive time), in addition to the number of rotations of the conveying screw 229.

[0034] 2. Developer remaining amount detection device Next, a method for detecting the amount of toner remaining in the developing container 207 (developing device 209) by pixel counting in this embodiment will be described.

[0035] In this embodiment, the CPU 213 of the engine controller 212 is provided with a toner remaining amount detection device 240 as a developer remaining amount detection means for detecting the amount of toner remaining in the developing container 207. The toner remaining amount detection device 240 has a pixel count measurement unit 241 that measures (counts) a count value (pixel count value) of the number of pixels of an output image formed on the recording material P by an image forming operation. The toner remaining amount detection device 240 also has a toner remaining amount calculation unit 242 that calculates the amount of toner remaining in the developing container 207 based on the measured pixel count value. In this embodiment, the toner remaining amount detection device 240 (pixel count measurement unit 241, toner remaining amount calculation unit 242) is realized by the CPU 213 executing a program stored in the ROM.

[0036] The pixel count measurement unit 241 counts the number of pixels where the semiconductor laser 203 of the exposure device 204 irradiates the photosensitive drum 201 with laser light, based on image data during image formation operation, each time an image is output onto one sheet of recording material P. The count value of the number of pixels counted by this pixel count measurement unit 241 is set to a "pixel count value VCn." The image forming apparatus 200 of this embodiment has a resolution of 600 dpi, and the width of one pixel in the main scanning direction (a direction substantially parallel to the rotation axis direction of the photosensitive drum 201) is 42 μm. In this embodiment, the pixel count measurement unit 241 samples one pixel at a sampling period of 80 MHz.

[0037] The toner remaining amount calculation unit 242 calculates the amount of toner actually consumed from the developing container 207 based on the pixel count value VCn. The amount of toner consumed varies depending on the accumulated usage amount of the photosensitive drum 201 (e.g., the accumulated number of sheets used) and the usage environment of the image forming apparatus 200 (e.g., the temperature and humidity of the printing environment). Therefore, the toner remaining amount calculation unit 242 calculates a "toner consumption pixel count value VCnt" by multiplying the pixel count value VCn by a printing condition correction coefficient γ every time an image is output onto one sheet of recording material P. In this embodiment, the printing condition correction coefficient γ is set in consideration of the transfer efficiency. That is, in this embodiment, the toner remaining amount calculation unit 242 calculates the toner consumption pixel count value VCnt by the following formula (1). VCnt = VCn × γ (1)

[0038] The remaining toner amount calculation unit 242 accumulates the toner consumption pixel count value VCnt calculated each time an image is output onto one sheet of recording material P, and stores the accumulated toner consumption pixel count value VCnt in the nonvolatile memory 230 provided in the process cartridge 222. That is, the nonvolatile memory 230 provided in the process cartridge 222 stores a "cumulative toner consumption pixel count value VCd" from a state in which the toner 231 in the developing container 207 is full (toner remaining amount 100%). The remaining toner amount calculation unit 242 accumulates the calculated toner consumption pixel count value VCnt to the cumulative toner consumption pixel count value VCd stored in the nonvolatile memory 230, and updates and stores the cumulative toner consumption pixel count value VCnt in the nonvolatile memory 230.

[0039] Further, the toner remaining amount calculation unit 242 calculates the toner remaining amount TP in the developing container 207 based on a predetermined toner-out pixel count threshold VCth and a cumulative toner consumption pixel count value VCd. In this embodiment, the toner-out pixel count threshold VCth is set in advance and stored in the non-volatile memory 230. That is, in this embodiment, the toner remaining amount calculation unit 242 calculates the toner remaining amount TP in the developing container 207 by the following formula (2). TP[%]=(1-VCd / VCth)×100 (2)

[0040] In this embodiment, the amount of toner remaining in the developing container 207 is detected as described above, and the supply of toner from the toner cartridge 223 to the developing container 207 is controlled.

[0041] Compared to optical detection methods and capacitive detection methods, the pixel count method does not require any physical components in the process cartridge (developing device), and is therefore advantageous in making the device smaller and less expensive.

[0042] 3. Replenishing toner from the toner cartridge to the developing container Next, the supply of toner from the toner cartridge 223 to the developing container 207 (developing device 209) in this embodiment will be described.

[0043] In this embodiment, when the CPU 213 determines that the remaining toner amount TP in the developing container 207 obtained as described above is equal to or less than a predetermined toner supply threshold, the CPU 213 controls to execute toner supply from the toner cartridge 223 to the developing container 207. In this embodiment, the toner supply threshold is set in advance and stored in the non-volatile memory 230. In this embodiment, the toner supply threshold is set to 70% remaining toner. FIG. 2 is a flow chart for explaining the toner supply operation in this embodiment.

[0044] When the print operation is started (S010), the CPU 213 measures a pixel count value VCn based on image data in the pixel count measurement unit 241 (S020). The CPU 213 also calculates a toner consumption pixel count value VCnt in the toner remaining amount calculation unit 242 and adds it to the cumulative toner consumption pixel count value VCd (S025). The CPU 213 also calculates the toner remaining amount TP in the developing container 207 in the toner remaining amount calculation unit 242 (S030).

[0045] The CPU 213 compares the toner remaining amount TP in the developing container 207 with a predetermined toner supply threshold value and judges whether the toner remaining amount TP in the developing container 207 is equal to or less than the toner supply threshold value (S040). When the CPU 213 judges in S040 that the toner remaining amount TP in the developing container 207 is equal to or less than the toner supply threshold value, it sets the number of necessary supply operations (S050). In addition, the CPU 213 judges whether there is toner in the toner cartridge 223 (S060). When the CPU 213 judges in S060 that there is toner in the toner cartridge 223, it executes a toner supply operation from the toner cartridge 223 to the developing container 207 (S070). That is, the CPU 213 operates a drive motor (not shown) that drives the conveying screw 229 of the toner cartridge 223 to rotate the conveying screw 229 a predetermined number of times. Here, a toner supply operation for the predetermined number of rotations of the conveying screw 229 is regarded as one toner supply operation. Thereafter, the CPU 213 subtracts the number of toner supply operations that have been performed from the number of necessary supply operations that was set in S050, and updates the number of necessary supply operations (S080). The CPU 213 also determines whether the number of necessary supply operations has reached 0 (S090). If there is toner in the toner cartridge 223, the CPU 213 repeats the processes of S060 to S090 until the number of necessary supply operations reaches 0, and executes the toner supply operation for the number of necessary supply operations. If the number of necessary supply operations reaches 0 (S090), the CPU 213 stops the toner supply operation (S100). Thereafter, the CPU 213 resets the cumulative toner consumption pixel count value VCd to an initial value (zero in this embodiment) (S110). Then, the CPU 213 ends the print operation (S120).

[0046] Furthermore, if the CPU 213 determines in S040 that the remaining toner amount TP in the developing container 207 has not reached the toner supply threshold (is less than the toner supply threshold), it ends the printing operation without executing the toner supply operation (S120).

[0047] If the CPU 213 determines in S060 that the toner in the toner cartridge 223 is depleted, it suspends the toner supply operation (S061). The CPU 213 also resets the cumulative toner consumption pixel count value VCd to an initial value (zero in this embodiment) (S062). The CPU 213 then converts the number of necessary supply operations remaining at that time back into a pixel count value and records it as the cumulative toner consumption pixel count value VCd (S063). That is, the CPU 213 obtains a toner supply amount corresponding to the number of necessary supply operations remaining at the present time based on a previously obtained toner supply amount by one toner supply operation and the number of necessary supply operations remaining at the present time. The CPU 213 also converts the toner supply amount into a pixel number based on the previously obtained toner supply amount and a previously obtained toner consumption amount per pixel (unit toner consumption amount). The CPU 213 then stores the converted pixel number in the non-volatile memory 230 as the cumulative toner consumption pixel count value VCd, assuming that the toner equivalent to the above-mentioned toner supply amount has already been consumed. Thereafter, CPU 213 executes a notification on display unit 250 (S064) to prompt the user to replace toner cartridge 223. Then, CPU 213 ends the printing operation (S120).

[0048] In addition, the life of the process cartridge 222 may be set separately based on index values ​​of usage such as the number of rotations and rotation time of the developing roller 224 in the developing device 209, or index values ​​of usage such as the number of rotations and rotation time of the photosensitive drum 201.

[0049] In this embodiment, when the toner in the toner cartridge 223 runs out, even if the toner cartridge 223 is not replaced, the print operation can be performed until the remaining amount of toner in the developing container 207 reaches 0% (the cumulative toner consumption pixel count value VCd reaches the toner out pixel count threshold value VCth). Therefore, when the toner cartridge 223 is replaced, a large amount of toner is replenished to the developing container 207 at once in order to fill the toner in the developing container 207 (toner remaining amount 100%). However, when a large amount of toner is replenished to the developing container 207 at once, as described above, fogging is likely to occur, and more toner may be consumed than the toner consumption amount measured by the pixel count method. This may result in a state in which the actual remaining amount of toner is less than the remaining amount of toner detected by the pixel count method, causing image defects.

[0050] FIG. 3 is a graph showing the transition of the fog level when toner is replenished. The fog was quantified as follows. Using a reflection densitometer TC-MOR-45 manufactured by Tokyo Denshoku Co., Ltd., the reflection density D1 (%) of a new recording material P and the reflection density D2 (%) of the recording material P used for printing were measured, and the reflection density difference "D1-D2" (%) was taken as the fog value. In addition, the process cartridge 222 used had a toner amount (toner remaining amount) of 100 g in the developing container 207 when it was full (toner remaining amount 100%). In addition, three types of process cartridges 222 with different toner remaining amounts of 50%, 70%, and 90% were prepared. In addition, toner amounts of 50 g, 30 g, and 10 g were replenished to these three types of process cartridges 222 so that the toner in the developing container 207 was full. The toner replenishment amount can be expressed as a replenishment toner amount ratio. The replenishment toner amount ratio is expressed as the ratio (percentage) of the toner replenished this time to the amount of toner in the developing container 207 after this replenishment. Here, the replenishment toner amount ratios for the above three types of process cartridges 222 are 50%, 30%, and 10%. Then, using each process cartridge 222, the fog values ​​were measured for up to 100 prints before and after replenishment.

[0051] From the results in Figure 3, it can be seen that the fog value changes significantly before and immediately after replenishment, and that the fog value immediately after replenishment is greater than the fog value before replenishment. It can also be seen that the fog value tends to increase as the amount of toner replenished increases. It can also be seen that the fog value decreases as the number of prints increases immediately after replenishment, and after printing about 100 sheets, the fog value decreases to almost the same level as before replenishment (fog recovers). This is thought to be due to the following reasons.

[0052] The toner supplied from the toner cartridge 223 to the developing container 207 is new toner. In contrast, the toner in the developing container 207 is toner (referred to as toner in the developing container) that has rubbed against the members in the developing container 207 (developing roller 224, supply roller 228, developing blade 305, conveying member 227, etc.) or rubbed against each other. The difference between the new toner and the toner in the developing container appears in the difference in lubricity and chargeability, and the new toner tends to have higher lubricity and chargeability than the toner in the developing container. Therefore, immediately after replenishment, the new toner is supplied to the developing roller 224 in a lump and is coated on the lower layer of the toner coat on the developing roller 224. On the other hand, the toner in the developing container is coated on the upper layer of the toner coat on the developing roller 224. However, the chargeability of the toner in the developing container is reduced due to use, and the new toner is in the lower layer of the toner coat on the developing roller 224 and is not rubbed against the surface of the developing roller 224, so the charge amount (tribo: charge amount per unit mass) is reduced. This makes it easier for toner to adhere to areas other than the image area, resulting in fogging.

[0053] That is, new toner replenished from the toner cartridge 223 to the developing container 207 is selectively coated on the lower layer of the toner coat on the developing roller 224, and the toner in the developing container in the developing container 207 is coated on the upper layer of the toner coat on the developing roller 224. The toner in the developing container coated on the upper layer of the toner coat on the developing roller 224 does not come into contact with the surface of the developing roller 224. As a result, the toner in the developing container with a low charge amount is coated on the upper layer of the toner coat on the developing roller 224, and some of the toner may be charged to a positive polarity opposite to the normal charging polarity. This makes it easier for toner to adhere to areas other than the image area, resulting in fogging.

[0054] When the above-mentioned fog occurs, toner adheres to and is consumed in the white areas other than the areas that make up the image, resulting in more toner being consumed than the amount of toner consumed calculated from the number of pixels. As a result, a detection error may occur in which the actual amount of toner remaining is less than the amount of toner detected by the pixel count method.

[0055] Thereafter, as the printing operation is performed, the new toner in the developing container 207 and the toner in the developing container gradually mix together, and the toner coated on the developing roller 224 becomes uniform, thereby improving the above-mentioned fog.

[0056] Therefore, in this embodiment, the toner remaining amount calculation unit 242 multiplies the toner consumption pixel count value VCnt by a pixel count correction coefficient γt according to the ratio of the amount of replenished toner during a predetermined period until the fog is improved after toner is replenished from the toner cartridge 223 to the developing container 207. That is, in this embodiment, the toner remaining amount calculation unit 242 calculates the toner consumption pixel count value VCnt by the following formula (3). VCnt = VCn × γ × γt (3)

[0057] In this embodiment, the toner consumption pixel count value VCnt calculated by the above formula (3) is used to detect the amount of toner remaining in the developing container 207 as described above.

[0058] Here, in this embodiment, the pixel count correction coefficient γt is determined according to the supply toner amount ratio as described above. Also, the influence of fogging differs depending on the printing rate of the output image. Therefore, in this embodiment, the pixel count correction coefficient γt is determined according to the printing rate. The printing rate can be expressed as the ratio (percentage) of the number of pixels in the image portion to the total number of pixels in the image forming area (area where a toner image can be formed) on one sheet of recording material P, that is, the area ratio (percentage) of the image portion in the image forming area. That is, in this embodiment, the pixel count correction coefficient γt is determined according to the supply toner amount ratio and the printing rate.

[0059] FIG. 4 is a table showing the setting of the pixel count correction coefficient γt in this embodiment. In this embodiment, information on the pixel count correction coefficient γt as shown in FIG. 4 is preset and stored in the non-volatile memory 230 as table data or the like. As shown in FIG. 4, in this embodiment, if the printing rate is the same, the pixel count correction coefficient γt is made larger as the supply toner amount ratio increases. Also, if the supply toner amount ratio is the same, the pixel count correction coefficient γt is made smaller as the printing rate increases. Note that, for supply toner amount ratios between the supply toner amount ratios shown in FIG. 4, a pixel count correction coefficient γt obtained by interpolating the values ​​shown in FIG. 4 may be used.

[0060] In this embodiment, the toner supply threshold for determining whether toner supply is necessary is set to 70% of the toner remaining in the developing container 207. If toner supply is performed from when the toner remaining in the developing container 207 reaches 70% until the developing container 207 is full (toner remaining amount 100%), the supply toner amount ratio becomes 30%. In pixel count measurement when printing is performed thereafter, a pixel count correction coefficient γt according to the print rate is applied for the period until 100 sheets are printed. For example, when the print rate is 10%, the pixel count correction coefficient γt is selected as γt=1.0283, and is multiplied by the toner consumption pixel count value VCnt. In addition, the higher the print rate, the less susceptible to the effect of fogging, so the pixel count correction coefficient γt is selected and used as a value closer to 1 (smaller value).

[0061] If the toner in the toner cartridge 223 runs out during a toner supply operation, the supply toner amount ratio becomes smaller than the original supply toner amount ratio of 30%. In that case, the pixel count correction coefficient γt corresponding to the supply toner amount ratio calculated based on the amount of toner supplied until the toner in the toner cartridge 223 runs out is selected and used.

[0062] Furthermore, when the toner cartridge 223 is replaced, the supply toner amount ratio may become greater than 30%. In that case, the effect of fogging also becomes greater, so a larger value is selected and used as the pixel count correction coefficient γt.

[0063] In this embodiment, the toner-out pixel count threshold is set corresponding to a state in which the toner remaining in the developing container 207 is 0%. In such a case, for example, an upper limit on the amount of toner replenishment may be set separately. For example, when the amount of toner in the toner cartridge 223 is less than the amount of toner in the developing container 207, an upper limit on the amount of toner replenishment can be set. This makes it possible to prevent a situation in which all of the toner in the toner cartridge 223 is replenished to the developing container 207 at once, causing a notification to replace the toner cartridge 223 again immediately after replacing the toner cartridge 223.

[0064] Also, the fog value tends to be the largest on the first print immediately after the replenishment, and gradually decrease (the fog is improved) over the course of 100 prints. However, in this embodiment, the pixel count correction coefficient γt is set to a predetermined value obtained by averaging the increase in the amount of toner consumed due to fog until 100 prints are made. However, this is not limited to this, and the pixel count correction coefficient γt may be changed according to the number of prints. For example, the pixel count correction coefficient γt may be set to a value closer to 1 (smaller value) as the number of prints increases. Also, in this embodiment, the predetermined period for applying the pixel count correction coefficient γt is set to the period from when the toner is replenished from the toner cartridge 223 to the developing container 207 until 100 prints are made. However, this is not limited to this, and the predetermined period for applying the pixel count correction coefficient γt may be appropriately set according to the number of prints at which fog is likely to occur. Also, this predetermined period is not limited to being set according to the number of prints, and may be set according to any index value that correlates with the usage amount of the developing device 209 (developing roller 224), such as the number of rotations or driving time of the developing roller 224.

[0065] In this embodiment, the remaining amount of toner in the developing container 207 is calculated using the supply toner amount ratio, but the present invention is not limited to this, and the remaining amount of toner in the developing container 207 can be calculated based on information about the amount of toner supply (supplied toner). For example, the remaining amount of toner in the developing container 207 may be calculated using the amount of toner supply itself.

[0066] Using the image forming apparatus 200 of this embodiment, printing operations were performed continuously until the toner cartridge 223 was replaced several times. As a result, the detection error of the remaining toner amount by the pixel count method was sufficiently suppressed, and the occurrence of streaky image defects caused by a decrease in the amount of toner in the developing container 207 was sufficiently suppressed.

[0067] Thus, in this embodiment, the image forming apparatus 200 is a developing device 209 including an image carrier (photosensitive drum) 201, an electrostatic image forming means (charging roller 202, exposure device 204) for forming an image portion by an electrostatic image on the image carrier, a developing member (developing roller) 224 for supplying a developer to the image portion on the image carrier 201 to form a developer image on the image carrier 201, and a container (developing container) 207 for containing the developer to be supplied to the developing member 224. The developing device 209 supplies developer to the storage section 207 from a supply container (toner cartridge) 223 supplied with developer, and an acquisition section (toner remaining amount detection device) 240 acquires first information (video count value) on the number of pixels of the image portion and corrects the first information according to second information (toner supply amount, supply toner amount ratio) on the amount of developer supplied from the supply container 223 to the storage section 207 to acquire third information (toner remaining amount) on the amount of developer in the storage section. In this embodiment, the acquisition unit 240 is configured to acquire the third information by applying a correction coefficient (pixel count correction coefficient) γt according to the second information to the first information, and applies the first correction coefficient as the correction coefficient γt when the ratio of the amount of replenished developer to the amount of developer in the storage unit 207 after replenishment indicated by the second information (replenished toner amount ratio) is a first ratio, and applies a second correction coefficient larger than the first correction coefficient as the correction coefficient γt when the ratio indicated by the second information is a second ratio larger than the first ratio. Particularly, in this embodiment, the acquisition unit 240 corrects the first information according to the second information and fourth information (print rate) related to the area rate of the image portion to acquire the third information.In this case, the acquisition unit 240 is configured to acquire the third information by applying a correction coefficient γt according to the second information and the fourth information to the first information, and when a ratio of the amount of replenished developer to the amount of developer in the container 207 after replenishment indicated by the second information is a first ratio, if the area ratio indicated by the fourth information is a first area ratio, the acquisition unit 240 applies a first correction coefficient as the correction coefficient γt, and if the area ratio indicated by the fourth information is a second area ratio larger than the first area ratio, the acquisition unit 240 acquires the third information by applying a correction coefficient γt according to the second information and the fourth information. A second correction coefficient smaller than the first correction coefficient is applied as the coefficient γt, and when the ratio indicated by the second information is the second ratio larger than the first ratio, if the area ratio indicated by the fourth information is the first area ratio, a third correction coefficient larger than the first correction coefficient is applied as the correction coefficient γt, and if the area ratio indicated by the fourth information is the second area ratio, a fourth correction coefficient larger than the second correction coefficient and smaller than the third correction coefficient is applied as the correction coefficient γt. In this embodiment, the acquisition unit 240 corrects the first information according to the second information for a predetermined period correlated with the usage amount of the developing device 209 after the developer is replenished from the supply container 223 to the storage unit 207.

[0068] As described above, according to this embodiment, it is possible to suppress errors in detecting the remaining amount of toner using the pixel count method even if the amount of toner consumed increases due to fogging, which is likely to occur when toner is replenished to the developing container 207. This makes it possible to suppress the occurrence of streak-like image defects and the like.

[0069] [Example 2] Next, another embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the image forming apparatus of embodiment 1. Therefore, in the image forming apparatus of this embodiment, elements having the same or corresponding functions or configurations as those of the image forming apparatus of embodiment 1 are given the same reference numerals as those of embodiment 1, and detailed explanations are omitted.

[0070] In this embodiment, a case will be described in which the developing container 207 of a process cartridge 222 that has been used up to an accumulated usage amount equivalent to its lifespan (for example, the accumulated number of sheets used) is reused and refilled with new toner to produce a recycled process cartridge 222 (recycled production). When the process cartridge 222 is recycled, refilling the developing container 207 with new toner can easily cause fogging, increasing the amount of toner consumed and causing an error in detecting the amount of remaining toner using the pixel count method. In this embodiment, to prevent this, a correction coefficient to be multiplied by the toner consumption pixel count value VCnt is set (changed) according to the amount of new toner refilled (toner refill amount).

[0071] In this embodiment, the process cartridge 222 in which the developing container 207 is reused is produced through the following steps. Step 1: Removing the toner from the developer container A process of discharging the toner remaining in the developer container 207 from a toner filling port (not shown) provided in the developer container 207. ·Step 2: Cleaning A process to remove toner and dust from the reusable parts in the developing container 207 by air blowing or the like. Step 3: Replacement of parts A process of replacing non-reusable parts in the developing container 207 with new parts. Step 4: Toner refill A process of refilling new toner through a toner filling port (not shown) provided in the developer container 207 so that the toner in the developer container 207 reaches a predetermined amount, and then sealing the toner filling port.

[0072] However, even if the toner in the developing container is removed in the above step 1 and the toner in the developing container is cleaned in the above step 2, it is difficult to completely remove the toner in the developing container 207. Therefore, in the above step 4, new toner is replenished into the developing container 207 while the toner remains in the developing container 207.

[0073] Therefore, when the reused process cartridge 222 is first used, new toner refilled in the developing container 207 is selectively coated on the lower layer of the toner coat on the developing roller 224, and the toner in the developing container remaining in the developing container 207 is coated on the upper layer of the toner coat on the developing roller 224. The toner in the developing container coated on the upper layer of the toner coat on the developing roller 224 does not come into contact with the surface of the developing roller 224. As a result, the toner in the developing container with a low charge amount is coated on the upper layer of the toner coat on the developing roller 224, and some of the toner may be charged to a positive polarity. This makes it easier for toner to adhere to areas other than the image area, causing fogging.

[0074] FIG. 5 is a graph showing the transition of the fogging level at the start of use of a recycled process cartridge 222. The method of quantifying fogging is the same as that described in Example 1. Furthermore, in the recycled production of the process cartridge 222, three types of process cartridges 222 with different amounts of replenished toner were prepared. The amount of replenished toner can be expressed as a replenished toner amount ratio. The replenished toner amount ratio is expressed as the proportion (percentage) of the replenished toner to the amount of toner in the developing container 207 after replenishment. Here, three types of process cartridges 222 with replenished toner amount ratios of 100%, 90%, and 80% were prepared.

[0075] From the results in Figure 5, we can see that the smaller the replenishment toner amount ratio, the larger the fog value immediately after replenishment. In addition, when the replenishment toner amount ratio is 90% or 80%, the fog value decreases as the number of prints increases, and after printing about 100 sheets, the fog value decreases to almost the same level as when the replenishment toner amount ratio is 100% (fog is improved).

[0076] When the above-mentioned fog occurs, as in the first embodiment, the amount of toner consumed increases, and an error in detecting the amount of remaining toner using the pixel count method may occur.

[0077] Therefore, in this embodiment, the toner remaining amount calculation unit 242 multiplies the toner consumption pixel count value VCnt by a reuse production condition correction coefficient γrt corresponding to the toner replenishment amount (replenishment toner amount ratio) in the above-mentioned process 4 during a predetermined period from the start of use of the reused process cartridge 222 until the fogging is improved.

[0078] 6 is a table showing the setting of the reuse production condition correction coefficient γrt in this embodiment. In this embodiment, the information of the reuse production condition correction coefficient γrt as shown in FIG. 6 is set in advance and stored in the non-volatile memory 230 as table data or the like.

[0079] When there is no remaining toner in the developing container 207, the replenishment toner amount ratio is 100%, and the reuse production condition correction coefficient γrt is selected and used as 1. When the replenishment toner amount ratio is smaller than 100%, a larger value is selected and used as the reuse production condition correction coefficient γrt. Also, as described in the first embodiment, since the influence of fogging varies depending on the printing rate of the output image, the reuse production condition correction coefficient γrt according to the printing rate is selected and used. As shown in FIG. 6, in this embodiment, if the printing rate is the same, the reuse production condition correction coefficient γrt is made larger as the replenishment toner amount ratio is smaller. Also, if the replenishment toner amount ratio is the same, the reuse production condition correction coefficient γrt is made smaller as the printing rate is larger. Note that, for the replenishment toner amount ratio between the replenishment toner amount ratios shown in FIG. 6, the reuse production condition correction coefficient γrt obtained by interpolating the values ​​shown in FIG. 6 may be used.

[0080] In this embodiment, information on the amount of toner replenished (replenished toner amount ratio) in reuse production is recorded in the nonvolatile memory 230 provided in the process cartridge 222. For example, information on the amount of toner replenished (replenished toner amount ratio) in reuse production is stored in the nonvolatile memory 230 at the time of reuse production or at the time of shipping from a factory. When calculating the amount of toner actually consumed from the pixel count value VCn, the toner remaining amount calculation unit 242 determines the reuse production condition correction coefficient γrt by referring to the toner replenished amount (replenished toner amount ratio) recorded in the nonvolatile memory 230. Then, the toner remaining amount calculation unit 242 calculates the toner consumption pixel count value VCnt by the following formula (4). VCnt = VCn × γ × γrt (4)

[0081] In this embodiment, the predetermined period for applying the reuse production condition correction coefficient γrt is from the start of use of the reused process cartridge 222 until 100 sheets are printed. However, this is not limited to this, and the predetermined period for applying the reuse production condition correction coefficient γrt can be appropriately set according to the number of prints at which fogging is likely to occur. Also, the reuse production condition correction coefficient γrt may be changed according to the number of prints. For example, as the number of prints increases, the reuse production condition correction coefficient γrt can be set to a value closer to 1 (a smaller value). Also, this predetermined period is not limited to being set by the number of prints, and can be set by any index value that correlates with the usage amount of the developing device 209 (developing roller 224), such as the number of rotations or driving time of the developing roller 224.

[0082] In addition, in this embodiment, the process cartridge 222 of the image forming apparatus 200 configured to replenish new toner from the toner cartridge 223 to the developing container 207 is recycled, but the present invention is not limited to this. For example, even when the process cartridge 222 integrated with the toner cartridge 223 in this embodiment is recycled, the same effect as in this embodiment can be obtained by applying the control using the above-mentioned recycled production condition correction coefficient γrt similar to that in this embodiment.

[0083] Using the image forming apparatus 200 of this embodiment, printing operations were continuously performed with the recycled process cartridge 222. As a result, the detection error of the remaining toner amount by the pixel count method was sufficiently suppressed, and the occurrence of streaky image defects caused by a decrease in the amount of toner in the developing container 207 was sufficiently suppressed.

[0084] As described above, in this embodiment, the image forming apparatus 200 has a memory unit 230 that stores first information (toner replenishment amount, replenishment toner amount ratio) regarding the amount of developer replenished to the storage unit 207 of the developing device 209 produced by reusing the storage unit (developing container) 207, and an acquisition unit (toner remaining amount detection device) 240 that acquires second information regarding the number of pixels of the image portion on the image carrier 201, corrects the second information according to the first information stored in the memory unit 230, and acquires it as third information (toner remaining amount) regarding the amount of developer in the storage unit 207. In this embodiment, the acquisition unit 240 is configured to acquire the third information by applying a correction coefficient (recycling production condition correction coefficient) γrt according to the first information to the second information, and when the ratio of the amount of replenished developer to the amount of developer in the storage unit 207 after replenishment indicated by the first information (replenishment toner amount ratio) is a first ratio, the acquisition unit 240 applies a first correction coefficient as the correction coefficient γrt, and when the ratio indicated by the first information is a second ratio smaller than the first ratio, the acquisition unit 240 applies a second correction coefficient larger than the first correction coefficient as the correction coefficient γrt. Particularly, in this embodiment, the acquisition unit 240 corrects the second information according to the first information and fourth information (printing rate) related to the area rate of the image portion to acquire the third information.In this case, the acquisition unit 240 is configured to acquire the third information by applying a correction coefficient γrt according to the first information and the fourth information to the second information, and when the ratio of the amount of replenished developer to the amount of developer in the container 207 after replenishment indicated by the first information (replenished toner amount ratio) is a first ratio, if the area ratio indicated by the fourth information is a first area ratio, a first correction coefficient is applied as the correction coefficient γrt, and if the area ratio indicated by the fourth information is a second area ratio larger than the first area ratio, A second correction coefficient smaller than the first correction coefficient is applied as the correction coefficient γrt, and when the ratio indicated by the first information is a second ratio smaller than the first ratio, if the area ratio indicated by the fourth information is the first area ratio, a third correction coefficient larger than the first correction coefficient is applied as the correction coefficient γrt, and if the area ratio indicated by the fourth information is the second area ratio, a fourth correction coefficient larger than the second correction coefficient and smaller than the third correction coefficient is applied as the correction coefficient γrt. In this embodiment, the developing device 209 is detachable from the device body 220 of the image forming device 200, and the storage unit 230 is detachable from the device body 220 together with the developing device 209. In this embodiment, the acquisition unit 240 corrects the second information according to the first information for a predetermined period correlated with the usage amount of the developing device 209 from the start of use of the developing device 209 after the developer is replenished in the storage unit 207.

[0085] As described above, according to this embodiment, even if the amount of toner consumed increases due to fogging, which is likely to occur when starting to use a recycled process cartridge 222, it is possible to suppress detection errors of the amount of remaining toner using the pixel count method. This makes it possible to suppress the occurrence of streak-like image defects.

[0086] [Example 3] Next, another embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the image forming apparatus of embodiment 1. Therefore, in the image forming apparatus of this embodiment, elements having the same or corresponding functions or configurations as those of the image forming apparatus of embodiment 1 are given the same reference numerals as those of embodiment 1, and detailed explanations are omitted.

[0087] In this embodiment, the deterioration state of the developing roller 224 is detected, and a correction coefficient by which the toner consumption pixel count value VCnt is multiplied is set (changed) according to the deterioration state.

[0088] In this embodiment, the deteriorated state of the developing roller 224 is a state represented by an increase in the electrical resistance value of the developing roller 224 caused by toner adhering to the surface of the developing roller 224. When toner adheres to the surface of the developing roller 224, the toner in the toner coat on the developing roller 224 cannot come into contact with the surface of the developing roller 224, so that triboelectricity due to frictional charging decreases, and fogging becomes more likely to occur. In other words, fogging becomes more likely to occur due to the same mechanism as when new toner is coated on the lower layer of the toner coat on the developing roller 224 in the first and second embodiments. This increases the amount of toner consumed, which may cause an error in detecting the remaining toner amount using the pixel count method.

[0089] A method for detecting the electrical resistance value of the developing roller 224 in this embodiment will be described.

[0090] FIG. 7 is a schematic cross-sectional view of the image forming apparatus 200 of this embodiment. FIG. 7 shows a state when detecting the electrical resistance value of the developing roller 224 (a state in which the developing roller 224 is separated from the photosensitive drum 201 as described later). In this embodiment, a potential difference of 50 V is provided between the developing voltage (DC bias) applied to the developing roller 224 by the developing power source 255 and the regulated voltage (DC bias) applied to the developing blade 305 by the developing power source 255. Then, a current flowing between the developing roller 224 and the developing blade 305 is detected by a current detection circuit (current detection unit) 256 as a current detection means provided in the developing power source 255. In this embodiment, the CPU 213 measures this current value as an index value indicating the volume resistance of the developing roller 224. In this embodiment, the current value when a predetermined voltage is applied is measured as an index value indicating the electrical resistance value, but is not limited thereto. The voltage value when a predetermined current is supplied may be measured as an index value indicating the electrical resistance value, or the electrical resistance value itself may be measured based on the voltage value and current value (voltage-current characteristics). The CPU 231 stores information on the measured electrical resistance value (current value) of the developing roller 224 in the non-volatile memory 230.

[0091] In this embodiment, the current value (electrical resistance value) is measured while rotating the developing roller 224. This makes it possible to measure the average volume resistance of the developing roller 224 in the rotational direction.

[0092] In this embodiment, the current value (electrical resistance value) is measured during post-rotation after image formation (during cleanup (preparation) operation after image formation) as a non-image formation time. However, this is not limited to this, and the current value (electrical resistance value) can be measured at any timing during non-image formation such as during pre-rotation before image formation, during the sheet interval corresponding to the recording material P and recording material P during continuous image formation, during post-rotation after image formation, etc.

[0093] In addition, in this embodiment, in order to measure the current value (electrical resistance value) with as little toner as possible carried on the surface of the developing roller 224, the developing roller 224 is rotated with the rotation of the supply roller 228 and the transport member 227 stopped, and the current value (electrical resistance value) is measured.

[0094] Furthermore, in this embodiment, in order to measure the current value between the developing roller 224 and the regulating member 305, the current value (electrical resistance value) is measured in a state in which the developing roller 224 is separated from the photosensitive drum 201 by the separating mechanism 257.

[0095] 8 is a graph showing the change in current value measured by the above-mentioned method in a durability test in which images are formed from a new process cartridge 222 (remaining life 100%) to a low print rate (e.g., print rate 1%). The remaining life (%) of the process cartridge 222 is expressed as 100% when the process cartridge 222 is new and as 0% when the process cartridge 222 reaches a life set based on the number of rotations of the developing roller 224, etc. From the results in FIG. 8, it can be seen that the current value starts to decrease when the remaining life is about 25%, and when the remaining life exceeds 0%, the current value decreases to 1 / 5 to 1 / 10 of the value when the remaining life is 100%.

[0096] 9 is a graph showing the transition of the fog level in the durability test. The method of quantifying the fog is the same as that described in Example 1. From the results in FIG. 9, it can be seen that the fog value increases in synchronization with the large drop in the detected current value of the developing roller 224 shown in FIG.

[0097] This is believed to be due to the following reasons. That is, the adhesive force between the surface of developing roller 224 and toner increases due to wear of the surface of developing roller 224 and other reasons. As a result, the toner adheres to the surface of developing roller 224, increasing the electrical resistance value of developing roller 224, and toner in the toner coat on developing roller 224 may not be able to contact the surface of developing roller 224. As a result, toner with a low charge is coated on the upper layer of the toner coat on developing roller 224, and some of the toner may be charged to a positive polarity. This makes it easier for toner to adhere to areas other than the image area, resulting in fogging.

[0098] When the above-mentioned fog occurs, as in the first and second embodiments, the amount of toner consumed increases, and an error in detecting the amount of remaining toner using the pixel count method may occur.

[0099] Therefore, in this embodiment, when calculating the amount of toner actually consumed from the pixel count value VCn, the remaining toner calculation unit 242 determines the developing roller correction coefficient γrd by referring to the detected current value (electrical resistance value) of the developing roller 224. Then, the remaining toner calculation unit 242 calculates the toner consumption pixel count value VCnt by the following formula (5). VCnt = VCn × γ × γrd (5)

[0100] Fig. 10 is a table showing the setting of the developing roller correction coefficient γrd in this embodiment. The current value ratio is expressed with the current value of the developing roller 224 (process cartridge 220) when it is new being set as 100%. In this embodiment, information on the developing roller correction coefficient γrd as shown in Fig. 10 is set in advance and stored in the non-volatile memory 230 as table data or the like.

[0101] When the developing roller 224 is new, the current value ratio is 100%, and the developing roller correction coefficient γrd is selected and used as 1. When the developing roller 224 is used repeatedly and the current value ratio decreases, a larger value is selected and used as the developing roller correction coefficient γrd. Also, as described in the first embodiment, the influence of fogging varies depending on the printing rate of the output image, so the developing roller correction coefficient γrd according to the printing rate is selected and used. As shown in FIG. 10, in this embodiment, if the printing rate is the same, the developing roller correction coefficient γrd is increased as the current value ratio decreases (the electrical resistance value increases). Also, if the current value ratio (electrical resistance value) is the same, the developing roller correction coefficient γrd is decreased as the printing rate increases. Note that, for the current value ratios between the current value ratios shown in FIG. 10, the developing roller correction coefficient γrd obtained by interpolating the values ​​shown in FIG. 10 may be used.

[0102] Using the image forming apparatus 200 of this embodiment, printing was performed continuously while measuring the current value (electrical resistance value) of the developing roller 224. As a result, the detection error of the remaining toner amount by the pixel count method was sufficiently suppressed, and the occurrence of streaky image defects caused by a decrease in the amount of toner in the developing container 207 was sufficiently suppressed.

[0103] Thus, in this embodiment, the image forming apparatus 200 has a first acquisition unit (current detection circuit 256, CPU 213) that supplies a current or voltage to the developing member (developing roller) 224 to acquire first information (current value) regarding the electrical resistance value of the developing member 224, and a second acquisition unit (toner remaining amount detection device) 240 that acquires second information regarding the number of pixels of the image portion on the image carrier 201, corrects the second information according to the first information, and acquires it as third information (toner remaining amount) regarding the amount of developer in the storage unit 207. In this embodiment, the second acquisition unit 240 is configured to acquire the third information by applying a correction coefficient (developing roller correction coefficient) γrd according to the first information to the second information, and applies a first correction coefficient as the correction coefficient γrd when the electric resistance value indicated by the first information is a first value, and applies a second correction coefficient larger than the first correction coefficient as the correction coefficient γrd when the electric resistivity indicated by the first information is a second value larger than the first value. Particularly, in this embodiment, the second acquisition unit 240 corrects the second information according to the first information and fourth information related to the area ratio of the image portion to acquire the third information. In this case, the second acquisition unit 240 is configured to acquire the third information by applying a correction coefficient γrd corresponding to the first information and the fourth information to the second information, and when the electrical resistance value indicated by the first information is a first value, if the area ratio indicated by the fourth information is a first area ratio, a first correction coefficient is applied as the correction coefficient γrd, and when the area ratio indicated by the fourth information is a second area ratio larger than the first area ratio, a second correction coefficient smaller than the first correction coefficient is applied as the correction coefficient γrd; when the electrical resistance value indicated by the first information is a second value larger than the first value, if the area ratio indicated by the fourth information is the first area ratio, a third correction coefficient larger than the first correction coefficient is applied as the correction coefficient γrd; and when the area ratio indicated by the fourth information is the second area ratio, a fourth correction coefficient larger than the second correction coefficient and smaller than the third correction coefficient is applied as the correction coefficient γrd.In this embodiment, the developing device 209 is equipped with a regulating member (developing blade) 305 that contacts the developing member 224 to regulate the amount of developer on the developing member, and the first acquisition unit 213 forms a potential difference between the developing member 224 and the regulating member 305, and acquires the above-mentioned first information based on the current flowing between the developing member 224 and the regulating member 305.

[0104] As described above, according to this embodiment, it is possible to suppress errors in detecting the remaining amount of toner using the pixel count method even when the amount of toner consumed increases due to fogging, which is likely to occur when the developing roller 224 deteriorates. This makes it possible to suppress the occurrence of streak-like image defects and the like.

[0105] [others] Although the present invention has been described above with reference to specific embodiments, the present invention is not limited to the above-mentioned embodiments.

[0106] The notification (notification) of information to an operator such as a user or a service person, such as a display, which has been described in the above embodiment as being performed on the display unit of the image forming apparatus, may be performed on an external device such as a personal computer communicably connected to the image forming apparatus. The notification (notification) of information to an operator is not limited to the display of a message on the display unit. For example, the notification may be a warning sound or voice generated by a sound generating unit, or a light turned on or blinked by a light emitting unit.

[0107] Furthermore, the image forming apparatus to which the present invention can be applied is not limited to the image forming apparatus having the basic configuration shown in the above embodiment. For example, the present invention can be applied to a color laser printer that has multiple detachable process cartridges and transfers multiple color toner images to a recording material using an intermediate transfer body such as an intermediate transfer belt to form a full color image. In the above embodiment, the image forming apparatus is configured so that the process cartridge is detachable, but the present invention can also be applied to an image forming apparatus in which a process unit similar to that constituting the process cartridge in the above embodiment is provided in the apparatus main body.

[0108] In the above embodiment, the developing device uses a contact development method in which the image carrier and the developer carrier are arranged in contact with each other, but is not limited to this. The developing device may use a two-component development method using a two-component developer, or a non-contact development method in which the image carrier and the developer carrier are arranged opposite each other with a predetermined gap therebetween.

[0109] In addition, the amount of developer in the developing container is not limited to being counted down as the remaining amount of developer, but may be counted up as the amount of developer consumed. In this case, when the container is full, the developer consumption is 0%, and when the amount of developer in the developing container has decreased to a predetermined amount, the developer consumption is 100%.

[0110] In addition, the supply device that supplies developer from the supply container to the developing container is not limited to a conveying screw, and may be, for example, a variable volume pump, etc. In addition, the amount of developer in the supply container is not limited to detection based on the driving amount of the supply device, such as the number of rotations of the conveying screw, and may be detected by a conventionally known optical detection method or electrostatic capacitance detection method, etc.

[0111] Furthermore, the information stored in a memory unit provided in a unit (process cartridge) that is detachable from the main body of the image forming apparatus in the above-described embodiment may also be stored in a memory unit provided in the main body of the image forming apparatus, or in a memory unit provided in a device connected to the image forming apparatus via a network.

[0112] In the above embodiment, the correction coefficients γt, γrt, and γrd are set according to the print rate in addition to the supply toner amount ratio (amount of developer supply), the replenishment toner amount ratio (amount of developer supply), and the current value ratio (electrical resistance value of the developing member), but are not limited to this. The correction coefficients γt, γrt, and γrd may be set according to only the supply toner amount ratio (amount of developer supply), the replenishment toner amount ratio (amount of developer supply), and the current value ratio (electrical resistance value of the developing member).

[0113] In the above embodiment, the pixel number information is multiplied by the correction coefficient to obtain the corrected developer amount information, but the present invention is not limited to such an embodiment. For example, the information on the unit toner consumption amount may be set according to the developer supply amount (embodiment 1), the developer refill amount (embodiment 2), or the electrical resistance value of the developing member (embodiment 3) so as to obtain the same result as the correction using the correction coefficient in the above embodiment. [Explanation of symbols]

[0114] 200 Image forming device 201 Photosensitive drum (image carrier) 207 Developer container 209 Developing device 222 Process cartridge 223 Toner cartridge (supply container) 224 Developing roller 231 Toner in developing container 232 Toner in toner cartridge 240 Toner remaining amount detection device (acquisition unit)

Claims

1. an image carrier; an electrostatic image forming means for forming an image portion by an electrostatic image on the image carrier; a developing device including a developing member that supplies a developer to the image portion on the image carrier to form a developer image on the image carrier, and a container that contains the developer to be supplied to the developing member, wherein the developer is replenished to the container from a supply container connected to the container; an acquiring unit that acquires first information regarding the number of pixels of the image portion, corrects the first information according to second information regarding the amount of developer replenished from the supply container to the container, and acquires the corrected information as third information regarding the amount of developer in the container; An image forming apparatus comprising:

2. The image forming apparatus of claim 1, wherein the acquisition unit is configured to acquire the third information by applying a correction coefficient corresponding to the second information to the first information, and when the ratio of the amount of replenished developer to the amount of developer in the storage unit after replenishment indicated by the second information is a first ratio, the acquisition unit applies a first correction coefficient as the correction coefficient, and when the ratio indicated by the second information is a second ratio greater than the first ratio, the acquisition unit applies a second correction coefficient greater than the first correction coefficient as the correction coefficient.

3. 2. The image forming apparatus according to claim 1, wherein the acquisition unit acquires the third information by correcting the first information in accordance with the second information and fourth information relating to the area ratio of the image portion.

4. The acquisition unit a correction coefficient according to the second information and the fourth information is applied to the first information to acquire the third information; When the ratio of the amount of replenished developer to the amount of developer in the container after replenishment, which is indicated by the second information, is a first ratio, if the area ratio indicated by the fourth information is a first area ratio, a first correction coefficient is applied as the correction coefficient, and if the area ratio indicated by the fourth information is a second area ratio that is larger than the first area ratio, a second correction coefficient that is smaller than the first correction coefficient is applied as the correction coefficient; 4. The image forming apparatus according to claim 3, wherein, when the ratio indicated by the second information is a second ratio greater than the first ratio, if the area ratio indicated by the fourth information is the first area ratio, a third correction coefficient greater than the first correction coefficient is applied as the correction coefficient, and if the area ratio indicated by the fourth information is the second area ratio, a fourth correction coefficient greater than the second correction coefficient and smaller than the third correction coefficient is applied as the correction coefficient.

5. The image forming apparatus according to any one of claims 1 to 4, characterized in that the acquisition unit corrects the first information according to the second information for a predetermined period of time that correlates with the amount of usage of the developing device since developer was replenished from the supply container to the storage unit.

6. an image carrier; an electrostatic image forming means for forming an image portion by an electrostatic image on the image carrier; a developing device including a developing member that supplies a developer to the image portion on the image carrier to form a developer image on the image carrier, and a container that contains the developer to be supplied to the developing member; a storage unit configured to store first information regarding an amount of developer replenished in the container of the developing device produced by reusing the container; an acquiring unit that acquires second information related to the number of pixels of the image portion, corrects the second information according to the first information stored in the storage unit, and acquires the second information as third information related to the amount of developer in the container; An image forming apparatus comprising:

7. The image forming apparatus of claim 6, wherein the acquisition unit is configured to acquire the third information by applying a correction coefficient corresponding to the first information to the second information, and when the ratio of the amount of replenished developer to the amount of developer in the storage unit after replenishment indicated by the first information is a first ratio, the acquisition unit applies a first correction coefficient as the correction coefficient, and when the ratio indicated by the first information is a second ratio smaller than the first ratio, the acquisition unit applies a second correction coefficient larger than the first correction coefficient as the correction coefficient.

8. 7. The image forming apparatus according to claim 6, wherein the acquisition unit acquires the third information by correcting the second information in accordance with the first information and fourth information relating to the area ratio of the image portion.

9. The acquisition unit a correction coefficient according to the first information and the fourth information is applied to the second information to acquire the third information; When the ratio of the amount of replenished developer to the amount of developer in the container after replenishment, which is indicated by the first information, is a first ratio, if the area ratio indicated by the fourth information is a first area ratio, a first correction coefficient is applied as the correction coefficient, and if the area ratio indicated by the fourth information is a second area ratio that is larger than the first area ratio, a second correction coefficient that is smaller than the first correction coefficient is applied as the correction coefficient; 9. The image forming apparatus according to claim 8, wherein, when the ratio indicated by the first information is a second ratio smaller than the first ratio, if the area ratio indicated by the fourth information is the first area ratio, a third correction coefficient larger than the first correction coefficient is applied as the correction coefficient, and if the area ratio indicated by the fourth information is the second area ratio, a fourth correction coefficient larger than the second correction coefficient and smaller than the third correction coefficient is applied as the correction coefficient.

10. 10. The image forming apparatus according to claim 6, wherein the developing device is detachable from the main body of the image forming apparatus, and the storage unit is detachable from the main body together with the developing device.

11. An image forming apparatus according to any one of claims 6 to 9, characterized in that the acquisition unit corrects the second information according to the first information for a predetermined period of time that correlates with the amount of usage of the developing device from the start of use of the developing device after developer is replenished in the storage unit.

12. an image carrier; an electrostatic image forming means for forming an image portion by an electrostatic image on the image carrier; a developing device including a developing member that supplies a developer to the image portion on the image carrier to form a developer image on the image carrier, and a container that contains the developer to be supplied to the developing member; a first acquiring unit that supplies a current or a voltage to the developing member to acquire first information relating to an electrical resistance value of the developing member; a second acquiring unit that acquires second information related to the number of pixels of the image portion, corrects the second information according to the first information, and acquires third information related to the amount of developer in the container; An image forming apparatus comprising:

13. The image forming apparatus of claim 12, wherein the second acquisition unit is configured to acquire the third information by applying a correction coefficient corresponding to the first information to the second information, and to apply a first correction coefficient as the correction coefficient when the electrical resistance value indicated by the first information is a first value, and to apply a second correction coefficient larger than the first correction coefficient as the correction coefficient when the electrical resistance value indicated by the first information is a second value larger than the first value.

14. 13. The image forming apparatus according to claim 12, wherein the second acquisition unit acquires the third information by correcting the second information in accordance with the first information and fourth information relating to an area ratio of the image portion.

15. The second acquisition unit a correction coefficient according to the first information and the fourth information is applied to the second information to acquire the third information; When the electrical resistance value indicated by the first information is a first value, if the area ratio indicated by the fourth information is a first area ratio, a first correction coefficient is applied as the correction coefficient, and if the area ratio indicated by the fourth information is a second area ratio that is larger than the first area ratio, a second correction coefficient that is smaller than the first correction coefficient is applied as the correction coefficient; 15. The image forming apparatus according to claim 14, wherein, when the electrical resistance value indicated by the first information is a second value greater than the first value, if the area ratio indicated by the fourth information is the first area ratio, a third correction coefficient greater than the first correction coefficient is applied as the correction coefficient, and if the area ratio indicated by the fourth information is the second area ratio, a fourth correction coefficient greater than the second correction coefficient and smaller than the third correction coefficient is applied as the correction coefficient.

16. the developing device includes a regulating member that contacts the developing member to regulate the amount of developer on the developing member; 16. The image forming apparatus according to claim 12, wherein the first acquisition unit forms a potential difference between the developing member and the regulating member, and acquires the first information based on a current flowing between the developing member and the regulating member.

Images