Image forming apparatus

Abstract

In an image forming apparatus that performs toner ejection, the amount of toner consumed is suppressed. [Solution] The image forming apparatus comprises an image carrier, a charging member, an exposure apparatus, a developing member that supplies toner to the image carrier, an intermediate transfer body onto which the toner image is transferred, and a control unit that controls the surface potential of the image carrier, the control unit being configured to perform an image forming operation in which a toner image is transferred from the image carrier to the intermediate transfer body, and a toner ejection operation in which toner is supplied from the developing member to the image carrier, a portion of the supplied toner is recovered by the developing member, and a portion is moved to the intermediate transfer body, and a consumption amount acquisition unit that acquires the amount of toner consumed in the toner ejection operation based on a value relating to the amount of toner supplied from the developing member to the image carrier in the toner ejection operation and a correction coefficient relating to the amount of toner recovered by the developing member in the toner ejection operation.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus that forms an image on a recording material.

Background Art

[0002] Conventionally, as an image forming apparatus such as a copying machine or a laser beam printer, an image forming apparatus having a developing device that houses toner inside and an intermediate transfer body is known. In such an image forming apparatus, for example, if an image with a low printing rate is continuously output, the consumption of toner in the developing device hardly occurs, and the toner in the developing device may deteriorate, causing a decrease in image quality.

[0003] Patent Document 1 and Patent Document 2 disclose an image forming apparatus capable of executing an operation of discharging (forcing consumption of) deteriorated toner in a developing device separately from an image forming operation.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the above-described configuration, in the toner discharging operation, in addition to the deteriorated toner, fresh toner that has not deteriorated much is also discharged at the same time. That is, since toner that can be used without problems in the image forming operation is forcibly discharged, the toner consumption amount increases, and the life of the developing device and the cartridge having the developing device is shortened.

[0006] The present invention has been made in view of the above-mentioned problems, and aims to suppress toner consumption in an image forming apparatus that performs a toner ejection operation. [Means for solving the problem]

[0007] To achieve the above-mentioned objectives, the image forming apparatus according to this application is: Image carrier and, A charging member that charges the image carrier, An exposure apparatus that exposes the surface of the image carrier to form an electrostatic latent image, A developing member supplies toner to the image carrier and develops the electrostatic latent image formed on the surface of the image carrier to form a toner image, An intermediate transfer body that comes into contact with the image carrier to form a transfer nip, and in the transfer nip, the toner image formed on the surface of the image carrier is transferred; A control unit for controlling the surface potential of the image carrier, configured to perform an image forming operation in which a toner image is transferred from the image carrier to the intermediate transfer body, and a toner ejection operation in which toner is supplied from the developing member to the image carrier, a portion of the supplied toner is recovered by the developing member, and a portion is moved to the intermediate transfer body, A consumption amount acquisition unit acquires the amount of toner consumed in the toner ejection operation based on a value relating to the amount of toner supplied from the developing member to the image carrier in the toner ejection operation and a correction coefficient relating to the amount of toner recovered by the developing member in the toner ejection operation. It is characterized by being equipped with [the following features]. [Effects of the Invention]

[0008] According to the present invention, toner consumption can be suppressed in an image forming apparatus that performs a toner ejection operation. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view showing the general configuration of the printer engine of Example 1. [Figure 2] This is a schematic cross-sectional view showing the general configuration of the developing unit according to Example 1. [Figure 3] This is an explanatory diagram of the hardware configuration according to Example 1. [Figure 4] This is an explanatory diagram of the configuration of the engine control unit according to Embodiment 1. [Figure 5] This is an explanatory diagram of the weak exposure control of the image formation process according to Example 1. [Figure 6] This is an explanatory diagram of the method for recovering residual toner from transfer according to Example 1. [Figure 7] This is an explanatory diagram of the degraded toner ejection operation according to Example 1. [Figure 8] This is an explanatory diagram of the voltage and potential control for degraded toner ejection control according to Example 1. [Figure 9] This flowchart shows the control flow according to Example 1. [Figure 10] This is an explanatory diagram of the configuration of the engine control unit according to Embodiment 2. [Modes for carrying out the invention]

[0010] The embodiments for carrying out this invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in these embodiments should be appropriately modified depending on the configuration of the device to which the invention is applied and various conditions. In other words, the scope of this invention is not intended to be limited to the following embodiments. Furthermore, not all of the features described in the following embodiments are essential to the solution of the invention.

[0011] [Example 1] Hereinafter, an image forming apparatus according to Embodiment 1 to which the present invention is applicable will be described. In the following description, a case where the present invention is applied to an image forming apparatus using an electrophotographic image forming method for forming an image on a recording medium using an electrophotographic image forming process will be described. Examples of the image forming apparatus using the electrophotographic image forming method include an electrophotographic copying machine, an electrophotographic printer (such as an LED printer, a laser beam printer, etc.), an electrophotographic facsimile apparatus, and the like.

[0012] <Image forming apparatus> First, an overview of the overall configuration of a laser printer engine as the image forming apparatus according to Embodiment 1 will be described with reference to FIG. 1. FIG. 1 is a schematic cross-sectional view showing the schematic configuration of the printer engine 100 of this embodiment. With reference to FIG. 1, the configuration, operation, and control of the printer engine 100 of this embodiment will be described.

[0013] The printer engine 100 of this embodiment is a full-color laser printer adopting an in-line method and an intermediate transfer method.

[0014] The printer engine 100 can form a full-color image on a recording material P (for example, recording paper, plastic sheet) according to image information. The image information is input to the printer engine 100 from an image reading device or a host computer 1000 such as a personal computer communicably connected to the printer engine 100.

[0015] The printer engine 100 has first, second, third, and fourth process cartridges Sa, Sb, Sc, and Sd for forming images of respective colors of yellow (Y), magenta (M), cyan (C), and black (K) as a plurality of image forming units. In this embodiment, the first to fourth process cartridges Sa, Sb, Sc, and Sd are arranged in a row in a direction intersecting the vertical direction. In this embodiment, the first to fourth process cartridges Sa, The configuration and operation of Sb, Sc, and Sd are substantially the same, except that they form different colors in the resulting images. Therefore, unless otherwise specified, the subscripts a, b, c, and d used to indicate that an element is provided for a particular color will be omitted, and a general explanation will be provided.

[0016] In this embodiment, the printer engine 100 has four drum-type electrophotographic photoreceptors, namely photosensitive drums 1 (1a, 1b, 1c, 1d), arranged in parallel in a direction intersecting the vertical direction, as multiple image carriers. The photosensitive drums 1 are image carriers that are rotationally driven by a photosensitive drum drive source 85, which is a driving means. Around the photosensitive drums 1 are charging rollers 2 (2a, 2b, 2c, 2d), scanner units (exposure devices) 3 (3a, 3b, 3c, 3d), and developing units (developing devices) 4 (4a, 4b, 4c, 4d).

[0017] The charging roller 2 is a rotatable charging means (charging member) that uniformly charges the surface of the photosensitive drum 1. The scanner unit 3 is an exposure device (exposure means) that irradiates a laser to form an electrostatic image (electrostatic latent image) on the photosensitive drum 1 based on the output calculated by the CPU 207 from image information input from a host computer 1000 such as a personal computer. When the exposure means forms an electrostatic latent image corresponding to the image signal, the surface potential of the photosensitive drum 1 is stabilized by uniformly and weakly exposing the non-image area of ​​the surface of the photosensitive drum 1. Hereinafter, the formation of an electrostatic image by the exposure means will be distinguished as exposure, and uniformly exposing the non-image area will be distinguished as weak exposure. The developing unit 4 is a developing means that develops the electrostatic image as a developer (hereinafter referred to as toner) image.

[0018] The photosensitive drum 1, the charging roller 2 which acts as a process means on the photosensitive drum 1, and the developing unit 4 are integrated to form a process cartridge S. The process cartridge S is a cartridge that can be attached to and detached from the printer engine 100 via mounting means such as mounting guides and positioning members provided on the printer engine 100.

[0019] An intermediate transfer belt 10 is positioned opposite the four photosensitive drums 1, serving as an intermediate transfer body for transferring the toner image on the photosensitive drums 1 to the recording material P. The intermediate transfer belt 10, formed as an endless belt, contacts all of the photosensitive drums 1 and moves (rotates) in a circular motion in the direction of arrow R3 (clockwise) in Figure 1. The intermediate transfer belt 10 is stretched across multiple support members: a drive roller 11, a tension roller 12, and a secondary transfer opposing roller 13. The drive roller 11, as a drive member, rotates in the direction of arrow R2 (clockwise) in Figure 1, thereby driving the intermediate transfer belt 10 to rotate in the direction of arrow R3.

[0020] On the inner circumferential surface of the intermediate transfer belt 10, four primary transfer rollers 14 (14a, 14b, 14c, 14d) are arranged in parallel, facing each photosensitive drum 1, as primary transfer means. The primary transfer rollers 14 are (primary) transfer members that contact the intermediate transfer belt 10, press the intermediate transfer belt 10 toward the photosensitive drum 1, and form a primary transfer section (primary transfer nip) where the intermediate transfer belt 10 and the photosensitive drum 1 come into contact. A voltage with the opposite polarity to the normal charging polarity of the toner is applied to the primary transfer rollers 14 from a primary transfer high-voltage power supply circuit 15, which serves as a primary transfer voltage application means. As a result, the toner image on the photosensitive drum 1 is primary transferred onto the intermediate transfer belt 10. When forming a full-color image, the above process is performed sequentially in the first to fourth process cartridges Sa, Sb, Sc, and Sd, and the toner images of each color are superimposed and primary transferred onto the intermediate transfer belt 10.

[0021] A secondary transfer roller 20 is positioned on the outer circumferential surface of the intermediate transfer belt 10, facing the secondary transfer opposing roller 13, as a secondary transfer means. The secondary transfer roller 20 presses against the secondary transfer opposing roller 13 via the intermediate transfer belt 10, forming a secondary transfer portion (secondary transfer nip) where the intermediate transfer belt 10 and the secondary transfer roller 20 come into contact. That is the case.

[0022] A voltage opposite to the normal charging polarity of the toner is applied to the secondary transfer roller 20 from the secondary transfer high-voltage power supply circuit 21, which serves as a secondary transfer voltage application means. As a result, the four-color toner images on the intermediate transfer belt 10 are transferred collectively onto the recording material P by the action of the secondary transfer roller 20, which is in contact with the intermediate transfer belt 10 via the recording material P. The recording material P stored in the cassette 51 is transported to the secondary transfer section by the feeding means 50 in synchronization with the movement of the intermediate transfer belt 10.

[0023] The secondary transfer opposing roller 13 is cleaned and removed by an intermediate transfer belt cleaning device 16 via an intermediate transfer belt 10, and the residual secondary transfer toner remaining on the intermediate transfer belt 10 is collected in a waste toner container 17.

[0024] After the secondary transfer is complete, the recording material P, which carries the four-color toner images, is transported to the fixing device 30, specifically the fixing nip section formed by the fixing roller 31 and the pressure roller 32. There, the recording material P is heated and pressurized, causing the four colors of toner to melt and mix, fixing the recording material P, and it is then discharged from the printer engine 100. The printer engine 100 is also equipped with an environmental sensor 70 capable of detecting the temperature and humidity of the environment in which the device is installed.

[0025] Furthermore, the printer engine 100 is configured to form monochrome or multicolor images using only one desired image forming unit, or using only some (but not all) of the image forming units.

[0026] <Processing Cartridge> Next, the overall configuration of the process cartridge S installed in the printer engine 100 of this embodiment will be described.

[0027] The process cartridge S is composed of a photosensitive unit equipped with a photosensitive drum 1 and a charging roller 2, and a developing unit (developing device) 4 equipped with a developing roller 22, etc., integrated together. The device configuration of the developing unit 4 will be explained with reference to Figure 2. Figure 2 is a schematic cross-sectional view showing the general configuration of the developing unit 4.

[0028] The photosensitive drum 1 is rotatably supported on the main body of the printer engine 100 via a bearing (not shown). The photosensitive drum 1 is configured to rotate in the direction of arrow R1 (counterclockwise) in Figure 1 in accordance with the image forming operation when the driving force of a driving means (driving source) (not shown) is transmitted to the photoreceptor unit. The charging roller 2 is configured to rotate driven by the pressure of a conductive rubber roller portion that makes pressure contact with the photosensitive drum 1. In this embodiment, the charging roller 2 that makes pressure contact with the photosensitive drum 1 is used as the charging member that charges the photosensitive drum 1, but this is not the only option, and a non-contact charging method such as a corona charger may also be used.

[0029] As shown in Figure 2, the developing unit 4 includes a developing roller 22 (developer-carrying member) that carries toner T, a developing blade 23 (regulating member), and a developing frame 24 that fixes these together. The developing frame 24 includes a developing chamber 241 in which the developing roller 22 is arranged, and an anti-blowing sheet 242 that seals the developing opening (opening) that connects the developing chamber 241 to the outside world. The developing chamber 241 is a toner storage section that stores toner inside.

[0030] One end of the developing blade 23 is fixed to a fixing member 25. The fixing member 25 is fixed to the developing frame 24, so that the developing blade 23 and the developing frame 24 are integrated. The other end of the developing blade 23, opposite to the one end, is in contact with the developing roller 22, and is configured to regulate the amount of toner T coated on the developing roller 22 and to apply an electric charge. The developing roller 22 is It is positioned at the developing aperture and is arranged so as to be in contact with the photosensitive drum 1.

[0031] As shown in Figure 2, the developing roller 22 is a roller with an outer diameter of φ10 mm, having a structure in which a metal core 221, a base layer 222, and a surface layer 223 are sequentially laminated. The metal core 221 is φ6.0 mm. The base layer 222 is 2.0 mm thick and made of conductive silicone rubber. The surface layer 223 is made of urethane. The developing roller 22 is arranged to rotate in the direction of arrow R4 (clockwise direction) in Figure 2. The developing roller 22 rotates with a speed difference relative to the photosensitive drum 1 in order to control the amount of toner T developed onto the photosensitive drum 1.

[0032] As shown in Figure 2, the developing blade 23 is in contact with the developing roller 22 in a direction that is counter to the direction of rotation of the developing roller 22, thereby regulating the amount of toner T coated and imparting charge through triboelectricity. In other words, the direction from the end of the developing blade 23 on the side of the fixed member 25 to the end on the side of contact with the developing roller 22 is opposite to the direction of rotation of the developing roller 22 at the contact point between the developing blade 23 and the developing roller 22. Furthermore, by applying a predetermined DC voltage to the developing blade 23 and controlling the potential difference with the voltage applied to the developing roller 22, the amount of toner T coated and the amount of toner charge are controlled.

[0033] The supply roller 26 is constructed by providing a foamed urethane layer 262 around a core metal electrode 261 with an outer diameter of φ5.5 mm, which is a conductive support. The overall outer diameter of the supply roller 26, including the foamed urethane layer 262, is φ11 mm. At the point where the supply roller 26 contacts the developing roller 22, it rotates in the direction of arrow R5 in Figure 2 (clockwise) so that they have opposite speeds. The powder pressure of the toner T present around the foamed urethane layer 262 acts on it, and as the supply roller 26 rotates, the toner T is drawn into the foamed urethane layer 262.

[0034] The supply roller 26 containing toner T supplies toner T to the developing roller 22 at the point of contact with the developing roller 22, and further friction imparts a preliminary triboelectric charge to the toner T. On the other hand, the supply roller 26 that supplies toner T to the developing roller 22 also has the role of peeling off toner T that remains on the developing roller 22 without being developed in the developing section.

[0035] A predetermined DC voltage is applied to the supply roller 26. By controlling the potential difference between the voltage applied to the supply roller 26 and the voltage applied to the developing roller 22, the toner supply amount and the amount of preliminary triboelectric charge are controlled.

[0036] The toner T according to Example 1 is a non-magnetic toner with a normal charge polarity of negative polarity, manufactured by suspension polymerization, and becomes negatively charged when supported on the developing roller 22.

[0037] Due to prolonged friction with the developing blade 23, the toner T may deform in shape, or the external additives on the toner surface may peel off or become embedded. The deformation of the toner shape increases the contact area between the toner T and the photosensitive drum 1. Additionally, the peeling off of the external additives on the toner surface causes the resin component of the toner to come into contact with the photosensitive drum 1, and the embedding of the external additives into the toner further increases the contact area between the toner and the photosensitive drum 1. As a result, the non-electrostatic adhesion force to the photosensitive drum 1 becomes higher compared to when it is new. In the following explanation, this phenomenon will be referred to as the deterioration of toner T.

[0038] The process cartridge S is equipped with a cartridge non-volatile memory 27, which serves as a cartridge information storage unit that stores unique information for each color cartridge. The printer engine 100 uses the cartridge information stored in the cartridge non-volatile memory 27 (27a, 27b, 27c, 27d) to determine the toner consumption during image formation and the process cartridge S. Determine the remaining toner level.

[0039] <Hardware Configuration> Next, the hardware configuration in this embodiment will be explained using Figure 3. Figure 3 is an explanatory diagram of the hardware configuration according to this embodiment.

[0040] The printer engine 100 consists of a controller 200 and an engine control unit 201. The controller 200 receives image information and print commands from an external device, the host computer 1000. The controller 200 analyzes the received image information, converts it into bit data, and sends a print reservation command, a print start command, and a video signal for each page to the engine control unit 201 via the video interface unit 330.

[0041] The engine control unit 201 is a control IC (integrated circuit) consisting of a CPU 207, ROM 208, RAM 209, and I / O port 211. The CPU 207 loads the program and various data into the ROM 208 and executes the program using the RAM 209 as a working area. The above components can access the I / O port 211 via a bidirectional system bus 210.

[0042] Each I / O port 211 is connected to the laser illumination count circuit 800, the photosensitive drum drive source 85, the high-voltage charging power supply circuit 80, the high-voltage developing power supply circuit 81, the high-voltage developing blade power supply circuit 82, the high-voltage supply roller power supply circuit 83, the high-voltage primary transfer power supply circuit 15, the high-voltage secondary transfer power supply circuit 21, and the laser driver 62 of the scanner unit 3. The engine control unit 201 is a control unit that controls each actuator that realizes the image formation operation and ejection operation via these I / O ports 211. In addition, an environmental sensor 70 is connected to the I / O port 211 to detect the ambient temperature and humidity of the printer engine 100.

[0043] <Function Block> The configuration of the engine control unit 201, which controls the entire printer engine, will be explained using Figure 4. Figure 4 is an explanatory diagram of the configuration of the engine control unit 201 according to Embodiment 1.

[0044] As shown in Figure 4, the engine control unit 201 comprehensively controls the image forming execution unit 250, the ejection execution unit 251, the image forming control unit 252, and the cartridge life determination unit 254. The image forming control unit 252 comprehensively controls the photosensitive drum control unit 206, the primary transfer control unit 212, the secondary transfer control unit 202, the development control unit 203, the exposure control unit 204, the charging control unit 205, the development blade control unit 401, and the supply roller control unit 403. The cartridge life determination unit 254 comprehensively controls the consumption determination unit 253, which determines (acquires) the amount of toner consumed by various operations.

[0045] The photosensitive drum control unit 206 controls the photosensitive drum drive source 85 and controls the operation of the photosensitive drum 1, such as its rotation speed. The charging control unit 205 controls the charging high-voltage power supply circuit 80 and controls the charging voltage applied to the charging roller 2. The developing control unit 203 controls the developing high-voltage power supply circuit 81 and controls the developing voltage applied to the developing roller 22. The supply roller control unit 403 controls the supply roller high-voltage power supply circuit 83 and controls the voltage applied to the supply roller 26. The developing blade control unit 401 controls the developing blade high-voltage power supply circuit 82 and controls the voltage applied to the developing blade 23. The primary transfer control unit 212 controls the primary transfer high-voltage power supply circuit 15 and controls the transfer voltage (primary transfer voltage) applied to the primary transfer roller 14. The secondary transfer control unit 202 controls the secondary transfer high-voltage power supply circuit 21 and controls the transfer voltage (secondary transfer voltage) transferred to the secondary transfer roller 20. The exposure control unit 204 controls the exposure amount of the scanner unit 3. Thus, the engine control unit 201 (image forming control unit 252) is configured to control the voltages applied to various components, such as the charging voltage, developing voltage, and transfer voltage, as well as the exposure amount.

[0046] When the controller 200 receives print information and a print command from the host computer 1000, it instructs the engine control unit 201 to start printing. When the image forming execution unit 250 receives the instruction to start printing from the controller 200, it instructs the image forming control unit 252 to perform a print operation (image forming operation). When the image forming control unit 252 receives the instruction to perform a print operation, it executes the image forming operations necessary for the print operation. When the ejection execution unit 251 meets the ejection execution conditions, it instructs the image forming control unit 252 to perform an ejection operation. When the image forming control unit 252 receives the instruction to perform an ejection operation, it executes the image forming operations necessary for the ejection operation. The ejection execution unit 251 also counts up and clears the page counter used in the ejection execution conditions.

[0047] The consumption determination unit 253 (consumption acquisition unit) determines (acquires) the amount of toner consumed based on the laser illumination count value obtained from the laser illumination count circuit 800 and the cartridge information stored in the cartridge non-volatile memory 27. The consumption determination unit 253 changes the toner consumption calculation method according to the operation instructions from the image formation control unit 252. The cartridge life determination unit 254 determines the remaining amount of toner based on the toner consumption determined by the consumption determination unit 253 and the cumulative value of the toner consumption stored in the cartridge non-volatile memory 27. The cartridge life determination unit 254 also notifies the ejection execution unit 251 of the remaining toner amount for use under ejection execution conditions.

[0048] In this embodiment, toner consumption is measured using an image dot detection method that measures the number of image dots projected onto the surface of the photosensitive drum 1, which is a photoreceptor. As shown in the block diagram of Figure 4, the controller 200 receives an image signal S1 from the host computer 1000 and converts the image signal S1 into control signals for laser illumination amount and illumination timing. The controller 200 transmits these as image signals S1 to the laser illumination count circuit 800. The laser illumination count circuit 800 detects the laser illumination amount from the image signal S1 of the page transmitted from the controller 200, acquires and stores the pixels to which toner should be applied.

[0049] The laser illumination count circuit 800 is composed of a synchronous digital circuit. However, the system lock is not shown in Figure 4. As shown in Figure 4, the laser illumination count circuit 800 is composed of at least a flip-flop (hereinafter referred to as DF / F) 801, a gate 802, a counter 803, and a sample timing generation unit 804.

[0050] The image signal S1 input from the controller 200 is received by the flip-flop (DF / F) 801 and converted into a synchronization signal.

[0051] The sample timing generation unit 804 receives a horizontal enable signal S2 indicating the image area in the laser scanning direction and a vertical enable signal S3 indicating the image printing area perpendicular to the laser scanning direction. The horizontal enable signal S2 can be generated by a control logic circuit (not shown) inside the printer engine based on a horizontal synchronization signal (not shown). The vertical enable signal S3 can be generated by a control logic circuit (not shown) inside the printer engine 100 according to the image formation timing.

[0052] Gate 802 goes high (HIGH) when the signal synchronized with image signal S1 is ON at a timing determined by sample timing generation unit 804. Counter 803 counts the number of times gate 802 goes high (HIGH) within a predetermined image area, that is, the number of times image signal S1 is ON. The number of times image signal S1 is ON, as counted by counter 803, will be referred to as the count value Tcnt.

[0053] The count value Tcnt is sent to the CPU 207's consumption determination unit 253 when the controller 200 has received all of the image signals S1 for the page in question. The consumption determination unit 253 determines the toner consumption based on this count value Tcnt. In this embodiment, the remaining toner amount is determined by the cartridge life determination unit 254 accumulating the toner consumption determined by the consumption determination unit 253, and then using the ratio of the accumulated value to the toner life determination threshold.

[0054] In the example above, various processes were explained as being performed based on the processing of CPU207, but of course, some or all of the processing performed by CPU207 could be performed by an ASIC, which is an integrated circuit.

[0055] <Weak exposure in non-image areas> The control of weak exposure in the non-image area implemented in this embodiment will be explained using Figure 5. Figure 5 is an explanatory diagram of weak exposure control in the non-image area during the image formation process. In Figure 5, the image signal sent from the controller 200 is a multi-level signal (0 to 255) with 8 bits = 256 gradations in the depth direction. When this signal is 0, the laser light is off; when it is 255, it is fully on; and between 1 and 254, it has a value intermediate between the two.

[0056] The exposure level for non-image areas can be arbitrarily set by the level of the multi-level signal described above. In the following description, a level of 32 is used for this multi-level signal to perform exposure of non-image areas. Non-image areas where the image signal sent from the controller 200 to the exposure control unit 204 is 0 are converted to 32 by the image signal conversion circuit 68, and for image signals with values ​​from 1 to 255, they are compressed and converted from 33 to 255. Subsequently, the frequency modulation circuit 61 converts it into a serial time-axis signal, which in this example is used for pulse width modulation of each dot pulse with a resolution of 600 dots / inch.

[0057] This signal drives the laser driver 62, causing the laser diode 63 to emit light and the laser beam L to be emitted. This laser beam L passes through a correction optical system 67, which includes a polygon mirror 64, a lens 65, and a folding mirror 66, and is then irradiated onto the photosensitive drum 1 as scanning light. The frequency modulation circuit 61 may be located on the controller side, separate from the laser driver 62.

[0058] <Toner development and collection of leftover toner> The development of toner and the recovery of residual toner in the developing unit will be explained using Figures 6(a) to (d). Figures 6(a) to (d) are explanatory diagrams of the method for recovering residual toner. In Figures 6(a) and (c), circles enclosed by solid lines represent the toner after movement, and circles enclosed by dashed lines represent the toner before movement.

[0059] First, we will explain toner development using Figures 6(a) and 6(b). Figure 6(a) is a schematic diagram of the potential relationship when toner is developed. Figure 6(b) is a schematic diagram of the vicinity of the developing unit when toner is developed.

[0060] In this embodiment, the charging voltage Vpri applied to the charging roller 2 during image formation is -1200V, and the surface potential (post-charging potential Vp, post-charging drum potential) of the photosensitive drum 1 after charging is approximately -700V. Furthermore, the post-weak exposure potential Vd (post-weak exposure drum potential) formed in the non-image area of ​​the photosensitive drum 1 due to weak exposure is approximately -480V. The developing voltage Vdc applied to the developing roller 22 is -300V, and the post-exposure potential VL (post-exposure drum potential) of the photosensitive drum 1, whose charge has decayed due to exposure, is approximately -150V.

[0061] Primary transfer is the potential difference between the post-exposure potential VL and the primary transfer voltage Vtr. This is performed by the development voltage ΔVtr1. As shown in Figures 6(a) and (b), the potential difference between the development voltage Vdc and the post-exposure potential VL (hereinafter referred to as the development contrast ΔVc) causes the electrostatic latent image to be revealed in the development section where the negatively charged toner comes into contact with the photosensitive drum 1, and a toner image is formed. In addition, the potential difference between the development voltage Vdc and the post-exposure potential Vd formed by weak exposure (hereinafter referred to as the back contrast ΔVb) electrically holds the toner on the development roller 22 so that it does not transfer to the non-image area.

[0062] Next, we will explain how to process the toner that remains on the surface of the photosensitive drum 1 without being transferred to the intermediate transfer belt 10 during the primary transfer process (hereinafter referred to as residual toner).

[0063] In this embodiment, the remaining toner is recovered by the developing roller 22 and reused. The method of recovering the remaining toner by the developing roller 22 (hereinafter referred to as developing and recovering) will be explained using Figures 6(c) and 6(d). Figure 6(c) is a schematic diagram of the potential relationship during developing and recovering. Figure 6(d) is a schematic diagram of the vicinity of the developing unit during developing and recovering.

[0064] Of the toner developed on the photosensitive drum 1, the toner with a low charge and nearly neutral polarity cannot be transferred to the intermediate transfer belt 10 in the primary transfer process and remains on the surface of the photosensitive drum 1 as transfer residue toner. As shown in Figures 6(c) and (d), the transfer residue toner is charged to a normal charge polarity by the charging voltage Vpri as it passes through the contact area with the charging roller 2. At the same time, a post-charge potential Vp is formed on the surface of the photosensitive drum 1 by the charging voltage Vpri, and subsequently a post-weak exposure potential Vd is formed by weak exposure.

[0065] A potential difference (back contrast ΔVb) is generated between the potential of the developing roller 22 (developing voltage Vdc) formed by applying a DC voltage to the developing roller 22 and the potential Vd after weak exposure. The transfer residue toner on the drum surface where the potential Vd after weak exposure is formed is collected by the developing roller 22 by the electric field caused by the potential difference (back contrast ΔVb). The toner collected by the developing roller 22 is then reused. At this time, the transfer residue toner on the drum surface where the potential Vd after weak exposure is formed is charged with a normal charging polarity.

[0066] <Ejecting degraded toner> The printer engine 100 according to Example 1 is configured to efficiently discharge and process deteriorated toner generated as a result of using the process cartridge S from the developing container without discharging a large amount of toner that has not deteriorated significantly. In the following description, toner that has not deteriorated significantly will be referred to as fresh toner, and toner that has deteriorated as a result of using the process cartridge S will be referred to as deteriorated toner.

[0067] In this embodiment, the toner in the developing container (including both degraded toner and fresh toner) is ejected onto the photosensitive drum 1. Subsequently, the fresh toner is selectively recovered in the developing unit, and the degraded toner is recovered into the waste toner container 17 by the intermediate transfer belt cleaning device 16. Hereafter, the operation control of this toner ejection operation will be referred to as degraded toner ejection control.

[0068] The printer engine 100 according to Example 1 can selectively discharge deteriorated toner from the developing container while recovering a portion of the fresh toner into the developing container through deteriorated toner discharge control. Therefore, efficient discharge can be achieved, and unnecessary toner consumption can be suppressed.

[0069] The degraded toner ejection control (toner ejection operation) will be explained in more detail below using Figures 7(a) to (f) and Figure 8. Hereafter, the toner ejected from the developing container will be referred to as ejected toner. Figures 7(a) to (f) are explanatory diagrams of the degraded toner ejection operation, and the degraded toner This is a schematic diagram showing the movement of ejected toner when toner ejection control is performed. Figure 8 is an explanatory diagram of the voltage and potential control of degraded toner ejection control, and schematically represents the potential of the photosensitive drum 1, the developing voltage, the primary transfer voltage, and the movement of toner along the time axis during degraded toner ejection control. Figure 8 shows a graph with potential / voltage on the vertical axis and time on the horizontal axis, and the surface potential of a predetermined area that moves with the rotation of the photosensitive drum 1 is shown by a thick line, and the toner attached to that area is also shown. In Figures 7(a) to (f) and Figure 8, fresh toner is shown by a black circle, and degraded toner is shown by a white circle. In Figure 8, circles enclosed by a solid line represent the toner after movement, and circles enclosed by a dashed line represent the toner before movement.

[0070] This control system can be broadly divided into the following steps: A. Toner ejection from the developer unit, B. Toner passing through the primary transfer section, C. Toner passing through the charging section, D. Toner sorting in the developer unit, E. Transfer of degraded toner, and F. Processing of degraded toner. Each step will be explained below. Note that each step from A to E corresponds to Figures 7(a) to (e), and the range corresponding to each step is also indicated by arrows in Figure 8.

[0071] (A. Toner ejection from the developing unit 4) Figure 7(a) shows the toner ejection process within the developing unit 4. The toner ejection process is the process in which toner is supplied from the developing roller 22 to the photosensitive drum 1. When the degraded toner ejection control operation is started, the photosensitive drum 1 is uniformly charged to a predetermined negative potential by the charging roller 2 during the rotation process, and then exposed by the scanner unit 3. This creates a latent image potential of post-exposure potential VL on the photosensitive drum 1. In this embodiment, the post-charging potential Vp = -700V and the post-exposure potential VL = -100V.

[0072] Subsequently, as shown in Figure 7(a), at the position where the developing roller 22 and the photosensitive drum 1 come into contact, the toner carried on the developing roller 22 is ejected onto the photosensitive drum 1 by the potential difference between the developing voltage Vdc and the post-exposure potential VL (developing contrast ΔVc). At this time, the ejected toner contains a mixture of degraded toner and fresh toner. In this embodiment, the developing voltage Vdc is set to -300V. That is, the absolute value of the developing contrast ΔVc is 200V. In this embodiment, the development control unit 203 shown in Figure 3 can change the rotation speed of the developing roller 22 relative to the rotation speed of the photosensitive drum 1. In the ejection control of this embodiment, the developing roller 22 rotates at a speed of 140% (1.4 times) that of the photosensitive drum 1.

[0073] In this ejection control, the exposure amount by the scanner unit 3 is different from that during the image formation operation. Compared to the image formation operation, the post-exposure potential VL is increased (from -150V to -100V) (approaching a positive value), and the absolute value of the development contrast ΔVc is increased (from 150V to 200V). The post-exposure potential VL is increased to ensure that the toner on the development roller 22 is properly developed onto the photosensitive drum 1.

[0074] In the rotational direction of the photosensitive drum 1, the length of toner ejected at one time is preferably at least the length of one rotation of the developing roller 22, and preferably within the length of one rotation of the photosensitive drum 1. Since toner near the developing roller 22 is expected to be consumed, it is preferable that the length be at least the length of one rotation of the developing roller 22 in order to eject all the toner coated on the developing roller 22 immediately before ejection control. On the other hand, due to the potential relationship of the photosensitive drum, if toner ejection in the developing unit and the recovery of fresh toner in the developing unit described later are performed simultaneously, the recovery efficiency may decrease. Therefore, it is preferable that the length of the ejected toner in the rotational direction of the photosensitive drum 1 is within the length of one rotation of the photosensitive drum 1.

[0075] In this embodiment, during ejection control, toner equivalent to two rotations of the developing roller 22, totaling 44.8 mm (= 10 mm × 3.14 ÷ 1.4 × 2), is ejected. The length of the minute is 62.8 mm (= 20 mm × 3.14), and the length in the rotational direction of the photosensitive drum 1 from which the toner is ejected is less than the length of one rotation of the photosensitive drum 1. Although there is a limit to the length of toner ejected at one time in the rotational direction of the photosensitive drum 1, the total amount of toner ejected can be adjusted by repeating this ejection control.

[0076] (B. Passage of ejected toner through the primary transfer section) Figure 7(b) shows the process of the ejected toner passing through the primary transfer section. The primary transfer section is the process in which the toner supply section of the photosensitive drum 1, which is supplied with toner from the developing roller 22, first passes through the primary transfer section, which is the contact section between the photosensitive drum 1 and the intermediate transfer belt 10. When the ejected toner passes through the primary transfer section, a voltage of -600V is applied to the primary transfer roller 14 from the primary transfer high-voltage power supply circuit 15. As shown in Figure 7(b), a potential difference ΔV1 is formed between the post-exposure potential VL and the potential formed between the photosensitive drum 1 and the intermediate transfer belt 10 in the primary transfer section, such that the ejected toner (normally charged polarity) remains on the photosensitive drum 1. As a result, as shown in Figure 7(b), the toner ejected onto the toner supply section passes through the primary transfer section while remaining supported on the photosensitive drum 1.

[0077] If the potential formed on the intermediate transfer belt 10 is negative and its absolute value is greater than the absolute value of the post-exposure potential VL of the photosensitive drum 1, the ejected toner can be left on the photosensitive drum 1. This is because the ejected toner is charged to a normal charge polarity (negative polarity) due to friction with the developing blade 23. In other words, the toner is electrostatically attracted to the photosensitive drum 1 by the intermediate transfer belt 10, which has a negative potential greater than the absolute value of the potential of the photosensitive drum 1 (post-exposure potential VL). As for the potential difference, if it is about the same as or greater than the primary transfer contrast ΔVtr1 during image formation, the ejected toner can be left on the photosensitive drum 1. However, if the potential difference ΔV1 is too large, there is a risk that abnormal discharge will occur in the primary transfer section and reverse the polarity of the ejected toner, so in the configuration of this embodiment, it is preferable that the potential difference ΔV1 is less than 1500V. In this embodiment, a potential of -600V was formed on the intermediate transfer belt 10 by the primary transfer high-voltage power supply circuit 15 so that the absolute value of the potential difference ΔV1 was 500V.

[0078] (C. Passage of the charged part of the ejected toner) Figure 7(c) shows the process of the ejected toner passing through the charged section. The process of passing through the charged section is the process in which the toner supply section of the photosensitive drum 1, which is supplied with toner from the developing roller 22, passes through the charged section, which is the contact point between the photosensitive drum 1 and the charging roller 2. The ejected toner that has passed through the primary transfer section passes through the position where the charging roller 2 and the photosensitive drum 1 are in contact (the charged section). As shown in Figure 8, when the ejected toner passes through the charged section, a negative voltage of -1200V is applied to the charging roller 2. As a result, the potential difference between the potential of the photosensitive drum 1 and the voltage of the charging roller 2 (hereinafter referred to as the charging contrast ΔV2) allows the ejected toner to pass through without adhering to the charging roller 2. At this timing, the formation of the post-charged potential Vp and the imparting of charge to the ejected toner also occur simultaneously.

[0079] Furthermore, from any of the above viewpoints, it is preferable for the charge contrast ΔV2 to be somewhat large, and it is sufficient if it is equal to or greater than the charge contrast during image formation. On the other hand, if the charge contrast ΔV2 is too large, abnormal discharge may occur in the charged area, reversing the toner polarity and potentially causing it to adhere to the charged roller 2. For this reason, in this embodiment, the charge contrast ΔV2 was set to 1100V.

[0080] (D. Toner sorting in the developing department) Figure 7(d) shows the toner sorting process in the developing section. The toner sorting process is a process in which a portion of the toner on the surface of the photosensitive drum 1 supplied from the developing roller 22, that is, a portion of the toner from the toner supply section, is recovered by the developing roller 22. The discharged toner passes through the charged section. Afterward, the deteriorated toner and fresh toner are separated at the point where the developing roller 22 and the photosensitive drum 1 come into contact (hereinafter referred to as the developing section). The ejected toner that has passed through the charged section then passes through the developing section as the photosensitive drum 1 rotates. At this time, as shown in Figure 8, a developing voltage Vdc = -300V is applied to the developing roller 22, and a Vd = -600V is formed on the surface of the photosensitive drum due to weak exposure. The ejected toner is recovered by the back contrast ΔVb, which is the potential difference between this post-weak exposure potential Vd and the developing voltage Vdc.

[0081] The ejected toner contains a mixture of fresh toner and degraded toner. Degraded toner is toner whose shape has been deformed due to prolonged friction with the developing blade 23, or whose external additives on the toner surface have been peeled off or embedded. The deformation of the toner shape increases the contact area between the toner and the photosensitive drum 1. For example, when the external additive on the toner surface peels off, the resin component of the toner comes into contact with the photosensitive drum 1, and the external additive becomes embedded in the toner, increasing the contact area between the toner and the photosensitive drum 1. As a result, degraded toner has a higher non-electrostatic adhesion force to the photosensitive drum 1 compared to fresh toner. On the other hand, fresh toner has less degradation, and therefore has a lower non-electrostatic adhesion force to the photosensitive drum 1, the opposite of degraded toner.

[0082] As mentioned above, there is a difference in the non-electrostatic adhesion force between degraded toner and fresh toner. Therefore, when the ejected toner is recovered in the developer unit, fresh toner is more easily recovered, while degraded toner is less easily recovered. In Example 1, this difference in the non-electrostatic adhesion force between degraded toner and fresh toner is used to selectively recover fresh toner in the developer unit (and not selectively recover degraded toner), as shown in Figure 7(d). With this configuration, a large amount of fresh toner with less degradation can be recovered from the ejected toner, thus extending the lifespan of the developer unit 4 without wasting toner. Furthermore, the toner sorting process allows for toner sorting from the early stages of use of the process cartridge S (when it is in a near-new condition). On the other hand, as the usage time of the process cartridge S increases and the lifespan of the process cartridge S approaches its end, the proportion of degraded toner increases. Therefore, toner sorting is more effective when performed in the latter half of the lifespan of the process cartridge S, when the proportion of degraded toner is high.

[0083] The recovery efficiency of the ejected toner when it is collected by the developing roller 22 can be controlled by the back contrast ΔVb. First, as the absolute value of the back contrast ΔVb increases within the range below the discharge threshold, the electric field that moves the ejected toner toward the developing roller 22 becomes stronger, thus improving the recovery efficiency. However, if the back contrast ΔVb is greater than the discharge threshold between the developing roller 22 and the photosensitive drum 1, the polarity of the ejected toner is reversed due to discharge, and the recovery efficiency decreases.

[0084] On the other hand, if the absolute value of the back contrast ΔVb is small, not only does the recovery efficiency decrease, but the toner coated on the developing roller 22 cannot be retained on the developing roller 22 and is developed onto the photosensitive drum 1. This unintended development is called fogging. Therefore, the back contrast ΔVb must be set to be below the discharge threshold, within a range where fogging does not occur, and so that fresh toner is selectively recovered by the developing roller 22. Specifically, the back contrast ΔVb should be between 100V and 500V, and should be adjusted appropriately according to the properties of the toner being used (adhesion, charge amount, shape, and degree of degradation).

[0085] In this embodiment, the voltage applied to the developing roller 22 (developing voltage Vdc) was set to -300V so that the absolute value of the back contrast ΔVb was 300V. Although the back contrast ΔVb was formed by weak exposure in this embodiment, the configuration is not limited to this. For example, in the case of an image forming apparatus that does not have (or cannot implement) weak exposure, the charging voltage can be adjusted. By doing so, appropriate charge contrast ΔV2 and back contrast ΔVb can be ensured.

[0086] As described above, by controlling various voltages and exposure levels, a large portion of the fresh toner can be recovered by the developing roller 22, while a large portion of the degraded toner can be left on the photosensitive drum 1.

[0087] (E. Transfer of degraded toner) Figure 7(e) shows the degraded toner transfer process. The degraded toner transfer process is a process in which the toner supply section of the photosensitive drum 1, which has been supplied with toner from the developing roller 22, passes through the transfer section again, and the toner moves from the photosensitive drum 1 to the intermediate transfer belt 10. In other words, after the sorting and recovery process of the developing section, the degraded toner remaining on the photosensitive drum 1 is transferred to the intermediate transfer belt 10. The degraded toner that has passed through the developing section is charged with negative polarity (normal charge polarity). Therefore, as shown in Figure 7(e), a positive primary transfer voltage is applied to the primary transfer roller 14 to transfer the degraded toner to the intermediate transfer belt 10. At this time, as shown in Figure 8, the potential of the surface of the photosensitive drum 1 where the degraded toner remains is the post-weak exposure potential Vd. Then, the degraded toner is transferred to the intermediate transfer belt 10 by the potential difference ΔVtr2 between the post-weak exposure potential Vd and the primary transfer voltage Vtr.

[0088] As described above, degraded toner has a higher adhesion to the photosensitive drum 1 compared to fresh toner. Therefore, when transferring degraded toner to the intermediate transfer belt 10, the same potential difference as during normal image formation makes it difficult for the degraded toner to transfer to the intermediate transfer belt 10. For this reason, the potential difference ΔVtr2 needs to be set so that the degraded toner can be transferred to the intermediate transfer belt 10.

[0089] The degraded toner remaining on the photosensitive drum 1 is toner that was not collected by the developing roller 22 at the back contrast ΔVb during the previous recovery by the developing roller 22. Therefore, it is preferable that the potential difference ΔVtr2 be greater than or equal to the back contrast ΔVb during the development and recovery of fresh toner. Also, as mentioned above, the degraded toner has a high adhesion force to the photosensitive drum 1 and is difficult to transfer. For this reason, it is preferable that it be greater than the transfer contrast ΔVtr1 during normal image formation operation. In other words, it is preferable that the potential difference ΔVtr2 be greater than the larger of the back contrast ΔVb during the development and recovery of fresh toner and the transfer contrast ΔVtr1 during normal image formation operation. However, if the potential difference ΔVtr2 is too large, there is a risk of abnormal discharge in the primary transfer section, so it is preferable that the potential difference ΔVtr2 be less than 2000V.

[0090] In this example, when transferring the degraded toner to the intermediate transfer belt 10, the potential difference ΔVtr2 = 900V is set between the post-weak exposure potential Vd = -600V and the primary transfer voltage Vtr = +300V.

[0091] (F. Cleaning deteriorated toner) Figure 7(f) shows the cleaning process for degraded toner. The degraded toner transferred to the intermediate transfer belt 10 is sent to the intermediate transfer belt cleaning device 16 by the rotation of the intermediate transfer belt 10, and is collected and processed in the waste toner container 17.

[0092] In this embodiment, once the ejected toner has finished passing through the developing section (between Figure 7(e) and Figure 7(f)), the developing roller 22 is immediately separated from the photosensitive drum 1, and the rotation of the developing roller 22 is stopped. This is because, as the developing roller 22 rotates, the toner on the developing roller 22 rubs against the developing blade 23. Therefore, the purpose is to immediately separate the developing roller 22 from the photosensitive drum 1 when contact between the developing roller 22 and the photosensitive drum 1 is no longer necessary, thereby avoiding unnecessary rubbing.

[0093] In this embodiment, the degraded toner that has been negatively charged on the intermediate transfer belt 10 is transferred to the intermediate transfer belt When the material is sent to the cleaning device 16, a negative voltage is applied to the secondary transfer roller 20. This prevents degraded toner on the intermediate transfer belt 10 from adhering to the secondary transfer roller 20.

[0094] If the absolute value of the voltage applied to the secondary transfer roller 20 when the degraded toner on the intermediate transfer belt 10 passes through the contact area with the secondary transfer roller 20 is too low, the degraded toner will adhere to the secondary transfer roller 20. Conversely, if the absolute value of the applied voltage is too high, the toner polarity will reverse due to abnormal discharge, causing the degraded toner to adhere to the secondary transfer roller 20. Therefore, the voltage applied to the secondary transfer roller 20 is preferably around -300 to -1000V. In this embodiment, a voltage of -500V is applied to the secondary transfer roller 20. In this embodiment, although the secondary transfer roller 20 is in contact with the intermediate transfer belt 10, if there is a mechanism for separating the secondary transfer roller 20, the secondary transfer roller 20 may be separated from the intermediate transfer belt 10 to prevent the degraded toner from adhering to the secondary transfer roller 20.

[0095] Furthermore, the degraded toner transferred onto the intermediate transfer belt 10 does not necessarily need to be sent to the intermediate transfer belt cleaning device 16 during the ejection control. For example, the ejection control may be terminated once the degraded toner has been transferred onto the intermediate transfer belt 10. In this case, the degraded toner remaining on the intermediate transfer belt 10 may be sent to the intermediate transfer belt cleaning device 16 by the rotation of the intermediate transfer belt 10 during the next normal image forming operation, where it can be collected and processed. Doing so makes it possible to perform ejection control without causing unnecessary downtime.

[0096] In this embodiment, during output mode, the development voltage Vdc is operated at the same Vdc=-300V as during image formation, and the charging voltage and exposure amount are different from those during image formation. However, the configuration is not limited to this. For example, the development voltage Vdc may be changed to change the back contrast ΔVb or the development contrast ΔVc.

[0097] <Explanation of toner consumption and how toner level is determined> Next, the method for determining toner consumption and remaining toner in this embodiment will be explained. First, the method for determining toner consumption in this embodiment will be explained. In the degraded toner ejection control in this embodiment, a portion of the ejected toner is developed and recovered as fresh toner. Therefore, when determining toner consumption during degraded toner ejection, it is necessary to consider the amount of toner developed and recovered in relation to the amount of toner ejected. Hereinafter, the amount of toner consumed in the degraded toner ejection control will be referred to as the toner consumption Tcon. The toner consumption Tcon in this embodiment can be calculated by the following (Equation 1). (Equation 1) Tcon = (1-K) × Tcnt

[0098] In (Equation 1), Tcnt is the count value from the counter 803, as described above, and is the count value at which the image signal was turned on by the amount of toner ejected. In other words, the count value Tcnt is synonymous with the amount of toner supplied from the developing unit 4 to the surface of the photosensitive drum 1. Also, K in (Equation 1) is a correction coefficient that represents the estimated amount of toner to be developed and recovered. Specifically, the correction coefficient K is the ratio of the amount of toner recovered by the developing roller 22 to the amount of toner supplied from the developing roller 22 to the photosensitive drum 1 during the degraded toner ejection operation. The toner consumption Tcon when the toner ejection operation is performed will be smaller than the count value Tcnt, taking into account the amount of toner recovered by the developing unit 4.

[0099] In Example 1, the toner consumption Tcon during the toner ejection operation was obtained by multiplying the count value Tcnt, which corresponds to the amount of toner supplied from the developing unit 4, by a correction coefficient K, which corresponds to the toner recovery ratio. However, the configuration is not limited to this. For example, a different value related to the amount of toner may be used instead of the count value Tcnt, or the correction coefficient K may be used instead. Alternatively, a different correction coefficient related to the toner recovery amount or recovery rate may be used. Here, the value related to the toner amount includes the toner amount itself, a value equivalent to the toner amount, and a value proportional to the toner amount. In other words, the count value Tcnt and the correction coefficient K are merely examples, and the toner consumption amount Tcon should be obtained based on a value related to the amount of toner supplied from the developing roller 22 to the photosensitive drum 1 and a correction coefficient related to the amount of toner recovered by the developing roller 22 during the toner ejection operation.

[0100] Next, the method for determining the remaining toner amount Trem in the process cartridge S in this embodiment will be described. In this embodiment, the remaining toner amount Trem is determined from the cumulative value of the toner consumption Tcon and the toner remaining amount threshold. In this embodiment, the remaining toner amount Trem is calculated using the current cumulative value of the toner consumption Tcon. Specifically, the remaining toner amount Trem is calculated such that when the cumulative value of the toner consumption Tcon reaches the toner remaining amount threshold, the remaining toner amount Trem is 0%, and when the cumulative value of the toner consumption Tcon is 0, the remaining toner amount Trem is 100%. In this embodiment, the cumulative value of the toner consumption Tcon is stored in the cartridge non-volatile memory 27, so the remaining toner amount Trem can be carried over even if the process cartridge S is replaced.

[0101] <Control flow in Example 1> Next, the method for determining the toner consumption Tcon in Example 1 will be described. In Example 1, the correction coefficient K, which represents the estimated amount of toner recovered (recovery rate) during the deteriorated toner ejection operation, is set to a predetermined fixed value. In Example 1, the correction coefficient K is set to 0.7, and it is estimated that 70% of the ejected toner is developed and recovered. Furthermore, the correction coefficient K in Example 1 is a value stored in the cartridge non-volatile memory 27, and a value corresponding to the characteristics of the toner may be stored in the cartridge non-volatile memory 27 during cartridge manufacturing.

[0102] Next, the frequency of execution of degraded toner ejection control in Example 1 will be described. The purpose of degraded toner ejection control is to selectively eject a large amount of degraded toner from within the developing device. Therefore, it is preferable to execute the ejection control in the latter half of the lifespan of the process cartridge S, when the proportion of degraded toner increases. The correction coefficient K in Example 1 is a value determined by the inventors of this application through diligent study, and is a parameter determined on the premise that degraded toner ejection control is executed every 100 sheets. Therefore, in Example 1, degraded toner ejection control is performed every 100 sheets when the toner remaining amount is less than 50%, which is the latter half of the lifespan of the process cartridge S. In this example, the decision to execute degraded toner ejection control was made based on the remaining amount of toner, but the configuration is not limited to this. For example, the timing of starting degraded toner ejection control may be determined by the rotation distance of the photosensitive drum 1 or the amount of wear on the surface of the photosensitive drum 1.

[0103] It is preferable to perform the degraded toner ejection control during the post-rotation phase of the image formation operation, after the completion of the image formation operation, or between sheets of paper when forming images on multiple recording materials P consecutively, so as not to delay the start of the image formation operation.

[0104] Next, the control flow for the print operation and the degraded toner ejection operation in Example 1 will be explained using the flowchart shown in Figure 9. Figure 9 is a flowchart showing the control flow for the print operation (image forming operation) and the degraded toner ejection operation in Example 1. In Example 1, the engine control unit 201 of the printer engine 100 controls the operation of each part to enable the execution of the print operation and the degraded toner ejection operation.

[0105] First, in step (hereinafter referred to as S) 901, the image forming execution unit 250 determines whether or not it has received a print operation instruction. Specifically, if the image forming execution unit 250 has not received a print reservation command or a print start command, it determines whether or not it has received a print operation instruction. If it determines that it does not trust the system, it waits until it receives a print reservation command and a print start command. Meanwhile, when the image forming execution unit 250 receives the print reservation command and the print start command and the conditions are met, the image forming execution unit 250 instructs the image forming control unit 252 to start the image forming operation for the print operation.

[0106] When the image forming operation starts, at S902, the image forming control unit 252 performs pre-processing for the print operation (hereinafter referred to as the "pre-rotation sequence"). After the pre-rotation sequence is completed, at S903, the image forming control unit 252 outputs a / TOP signal and starts the print operation according to the first print reservation command.

[0107] In S904, the ejection unit 251 increments the page counter (count value Tcnt). Then, in S905, the consumption determination unit 253 determines the toner consumption per page during printing. Furthermore, in S906, the cartridge life determination unit 254 obtains (determines) the latest toner remaining amount Trem after printing based on the toner consumption determined in S905. In this embodiment, the toner consumption is determined in S905 and the toner remaining amount Trem is determined in S906 for each printed page, but the configuration is not limited to this. For example, the configuration may be such that the toner consumption and toner remaining amount Trem for multiple printed pages are determined all at once after the printing of multiple pages is completed.

[0108] Next, in S907, the ejection execution unit 251 determines whether or not to execute the degraded toner ejection sequence (operation). The ejection execution unit 251 determines to execute the degraded toner ejection sequence if the toner remaining amount Trem is less than 50% (Trem < 50%) and the page counter is 100 pages or more (Tcnt ≥ 100). On the other hand, if the toner remaining amount Trem is 50% or more (Trem ≥ 50%), or the page counter is less than 100 pages (Tcnt < 100), the ejection execution unit 251 determines not to execute the degraded toner ejection sequence.

[0109] If S907 determines YES (execute the degraded toner ejection sequence), proceed to S908 and execute the degraded toner ejection sequence. On the other hand, if S907 determines NO (do not execute the degraded toner ejection sequence), proceed to S912 without executing the degraded toner ejection sequence.

[0110] After the degraded toner ejection sequence is executed in S908, the ejection execution unit 251 clears the page counter in S909 (setting the count value Tcnt to zero). Next, in S910, the consumption determination unit 253 determines the toner consumption Tcon at the time of degraded toner ejection. Then, in S911, the cartridge life determination unit 254 obtains (determines) the latest toner remaining amount Trem after degraded toner ejection based on the toner consumption determined in S910. After obtaining the toner remaining amount Trem, the process proceeds to S912.

[0111] In S912, the image forming execution unit 250 determines whether or not the printing operation for the next page can be started. If it is determined that the printing operation for the next page cannot be started yet, it waits for the timing when the printing operation becomes possible. On the other hand, if it is determined that the printing operation for the next page can be started, the process proceeds to S913.

[0112] In S913, the image forming execution unit 250 determines whether or not it has received the next print operation instruction (print reservation command and print start command). If it has received the next print operation instruction, it returns to step S903 and starts printing the next page. On the other hand, if it has not received the next print operation instruction, it proceeds to S914. Then, in S914, the image forming control unit 252 performs post-processing of the print operation (hereinafter referred to as the "post-rotation sequence") and terminates the print operation.

[0113] Based on the above, the configuration of Example 1 enables efficient toner ejection by performing degraded toner ejection control, which selectively ejects degraded toner from the developing container while partially recovering fresh toner into the developing container. Furthermore, it is possible to obtain the remaining toner amount while considering the toner recovered during the toner ejection operation. In other words, it is possible to provide an image forming apparatus that suppresses unnecessary toner consumption while simultaneously suppressing deviations in the remaining toner amount due to development and recovery.

[0114] [Example 2] Next, Example 2 of the present invention will be described. Example 2 differs from Example 1 in the method for determining the correction coefficient K. Below, only the differences between the configuration of Example 2 and the configuration of Example 1 will be described. Components in the configuration of Example 2 that are the same as those in Example 1 are denoted by the same reference numerals and their descriptions are omitted.

[0115] Example 1 describes a method to suppress wasted toner consumption and reduce toner level discrepancies due to development and recovery by performing degraded toner ejection control using a predetermined fixed value correction coefficient K. Example 2 describes a method to further suppress toner level discrepancies due to development and recovery by performing degraded toner ejection control using a correction coefficient K that is suitable for the printer's installation environment and the user's printer usage.

[0116] <Function Block> The configuration of the engine control unit 201 in Example 2 will be explained with reference to Figure 10. Figure 10 is an explanatory diagram of the configuration of the engine control unit 201 according to Example 2.

[0117] The engine control unit 201 comprehensively controls the image formation control unit 252 and the cartridge life determination unit 254, as well as the environment detection unit 255 and the development drive distance measurement unit 256. The environment detection unit 255 acquires temperature information of the installation environment from the environment sensor 70 and notifies the consumption determination unit 253. The development drive distance measurement unit 256 measures the rotation distance of the development roller 22 and notifies the consumption determination unit 253. The development drive distance measurement unit 256 also measures the driving time of a motor (not shown) that rotates the development roller 22.

[0118] Furthermore, the consumption determination unit 253 in Example 2 determines the toner consumption based on the laser illumination count value obtained from the laser illumination count circuit 800 and information regarding the degree of toner degradation. The information regarding the degree of toner degradation in the consumption determination unit 253 includes, for example, temperature information and development rotation distance information.

[0119] <Description of the control flow in Example 2> Next, the method for determining toner consumption in Example 2 will be described. The correction coefficient K, which represents the estimated amount of toner developed and recovered in Example 2, is determined based on information regarding the degree of toner degradation. Specifically, the correction coefficient K is calculated by the following (Equation 2). (Formula 2) K=E×D

[0120] In Equation 2, E is the correction coefficient based on temperature information, and D is the correction coefficient based on development rotation distance (development travel distance). As shown in Equation 2, in Example 2, the correction coefficient K is determined based on the correction coefficient E based on temperature information and the correction coefficient D based on development rotation distance. The correction coefficient E based on temperature information is a value obtained by linear interpolation based on the values ​​shown in Table 1 below (Correction coefficient E based on temperature (environment) information).

[0121] [Table 1]

[0122] Toner degrades more easily in low-temperature environments and less easily in high-temperature environments. Therefore, in Example 2, the correction coefficient E in the environmental information is set higher as the ambient temperature in which the printer engine 100 is placed increases. Specifically, in Example 2, the correction coefficient E is set to 0.56 when the ambient temperature is 10°C, 0.7 when it is 23°C, and 0.7 when it is 32°C. Let's set it at 7.

[0123] When calculating the correction coefficient K, if the temperature information is greater than the upper limit, it is set to the upper limit (32°C in this example); if it is less than the lower limit, it is set to the lower limit (10°C in this example). The values ​​shown in Table 1 in Example 2 are values ​​stored in the cartridge non-volatile memory 27, which were determined in advance through evaluation tests and past performance data. The values ​​for determining the correction coefficient E are not limited to those described above; values ​​corresponding to the toner characteristics, etc., may be stored in the cartridge non-volatile memory 27 during cartridge manufacturing.

[0124] The correction coefficient D due to the development rotation distance, which is the rotation distance of the development roller 22, shall be a value linearly interpolated based on the values ​​shown in Table 2 (Correction coefficient D due to development rotation distance) below.

[0125] [Table 2]

[0126] Toner deteriorates more easily with longer contact times with the developing blade 23 and less easily with shorter contact times. Therefore, in Example 2, the correction coefficient D due to the developing rotation distance decreases as the contact time between the developing blade 23 and the toner increases. Specifically, in Example 2, the correction coefficient D is set to 0.8 when the developing rotation distance is 420,000 mm and to 1.0 when it is 210,000 mm. Note that the developing rotation distance of 420,000 mm is equivalent to the distance of passing 100 sheets of A3 paper, and the developing rotation distance of 210,000 mm is equivalent to the distance of passing 100 sheets of A4 paper.

[0127] When calculating the correction coefficient K, if the development rotation distance is greater than the upper limit, it is attached to the upper limit (420,000 mm in this example); if it is less than the lower limit, it is attached to the lower limit (210,000 mm in this example). The values ​​shown in Table 2 in Example 2 are values ​​stored in the cartridge non-volatile memory 27, which were determined in advance through evaluation tests and past performance data. The values ​​for determining the correction coefficient D are not limited to those described above; values ​​corresponding to the toner characteristics, etc., may be stored in the cartridge non-volatile memory 27 during cartridge manufacturing.

[0128] In Example 2, we described a case where the development rotation distance and temperature information are used to determine the correction coefficient K, which represents the estimated amount of toner to be developed and recovered. The configuration is not limited to the above. For example, the correction coefficient K may be determined based on only one of the development rotation distance and temperature information. Alternatively, the correction coefficient K may be determined based on unique information of the process cartridge S other than the development rotation distance, or based on information regarding the degree of toner degradation other than the development rotation distance and temperature information. Or, other parameters such as the saturated water vapor amount determined from temperature and humidity information, or average print density information during printing that can estimate the usage status of degraded toner may be used.

[0129] As explained above, by performing degraded toner ejection control using a correction coefficient K suitable for the printer's installation environment and usage conditions, it is possible to provide an image forming apparatus that can further suppress deviations in toner levels due to development and recovery.

[0130] In applying the present invention, the processes described in each of the above embodiments as being performed by one device may be divided and executed by multiple devices. Alternatively, the processes described as being performed by different devices may be executed by one device. For example, the control of the image forming control unit 252 and the control of the cartridge life determination unit 254 may be performed by different control units.

[0131] This embodiment includes the following configuration. (Composition 1) Image carrier and, A charging member that charges the image carrier, An exposure apparatus that exposes the surface of the image carrier to form an electrostatic latent image, A developing member supplies toner to the image carrier and develops the electrostatic latent image formed on the surface of the image carrier to form a toner image, An intermediate transfer body that comes into contact with the image carrier to form a transfer nip, and in the transfer nip, the toner image formed on the surface of the image carrier is transferred; A control unit for controlling the surface potential of the image carrier, configured to perform an image forming operation in which a toner image is transferred from the image carrier to the intermediate transfer body, and a toner ejection operation in which toner is supplied from the developing member to the image carrier, a portion of the supplied toner is recovered by the developing member, and a portion is moved to the intermediate transfer body, A consumption amount acquisition unit acquires the amount of toner consumed in the toner ejection operation based on a value relating to the amount of toner supplied from the developing member to the image carrier in the toner ejection operation and a correction coefficient relating to the amount of toner recovered by the developing member in the toner ejection operation. An image forming apparatus characterized by comprising: (Configuration 2) The correction coefficient is the ratio of the amount of toner recovered by the developing member to the amount of toner supplied from the developing member to the image carrier during the toner ejection operation. The image forming apparatus according to configuration 1, characterized in that the consumption acquisition unit acquires the toner consumption by multiplying the value relating to the toner amount by the correction coefficient. (Composition 3) The image forming apparatus according to configuration 1 or 2, characterized in that the correction coefficient is a predetermined fixed value. (Composition 4) The image forming apparatus according to configuration 1 or 2, characterized in that the correction coefficient is determined based on information regarding the degree of toner deterioration. (Composition 5) The image forming apparatus according to configuration 4, characterized in that the information regarding the degree of deterioration of the toner is temperature information of the environment in which the image forming apparatus is installed. (Composition 6) The image forming apparatus according to configuration 4, characterized in that the information regarding the degree of deterioration of the toner is the rotation distance of the developing member. (Composition 7) The image forming apparatus according to configuration 4, characterized in that the information regarding the degree of deterioration of the toner is the saturated water vapor amount determined based on temperature information and humidity information of the environment in which the image forming apparatus is installed. (Composition 8) The image forming apparatus according to configuration 4, characterized in that the information regarding the degree of toner degradation is the average print rate in the image forming operation. (Composition 9) A cartridge comprising the image carrier, the charging member, and the developing member, The cartridge includes a cartridge information storage unit that is mounted on the cartridge and stores the cartridge's unique information, Furthermore, The image forming apparatus according to any one of configurations 1, 2, or 6, characterized in that the correction coefficient is determined based on a value stored in the cartridge information storage unit. (Composition 10) The image forming apparatus according to configuration 9, characterized in that the control unit acquires the remaining amount of toner stored in the cartridge based on the consumption amount acquired by the consumption amount acquisition unit. (Composition 11) The transfer member further comprises contacting the intermediate transfer body, The image forming apparatus according to any one of configurations 1 to 10, characterized in that the control unit controls the charging voltage applied to the charging member, the exposure amount of the exposure apparatus, the developing voltage applied to the developing member, and the transfer voltage applied to the transfer member to control the surface potential of the image carrier. (Composition 12) The control unit, in the toner ejection operation, When the toner supplied to the image carrier first passes through the transfer portion, which is the contact portion between the image carrier and the intermediate transfer body, the transfer voltage is controlled to be negative and the absolute value of the transfer voltage is greater than the absolute value of the surface potential of the image carrier. The image forming apparatus according to configuration 11, characterized in that the value of the transfer voltage is controlled to become positive when the toner remaining on the surface of the image carrier passes through the transfer section again. [Explanation of Symbols]

[0132] 1...Photosensitive drum (image carrier), 2...Charging roller (charging component), 3...Scanner unit (exposure device), 10...Intermediate transfer belt (intermediate transfer body), 100...Image forming apparatus, 201...Engine control unit (control unit), 253...Consumption determination unit

Claims

1. Image carrier and, A charging member that charges the image carrier, An exposure apparatus that exposes the surface of the image carrier to form an electrostatic latent image, A developing member supplies toner to the image carrier and develops the electrostatic latent image formed on the surface of the image carrier to form a toner image, An intermediate transfer body that comes into contact with the image carrier to form a transfer nip, and in the transfer nip, the toner image formed on the surface of the image carrier is transferred; A control unit for controlling the surface potential of the image carrier, configured to perform an image forming operation in which a toner image is transferred from the image carrier to the intermediate transfer body, and a toner ejection operation in which toner is supplied from the developing member to the image carrier, a portion of the supplied toner is recovered by the developing member, and a portion is moved to the intermediate transfer body, A consumption amount acquisition unit acquires the amount of toner consumed in the toner ejection operation based on a value relating to the amount of toner supplied from the developing member to the image carrier in the toner ejection operation and a correction coefficient relating to the amount of toner recovered by the developing member in the toner ejection operation. An image forming apparatus characterized by comprising:

2. The correction coefficient is the ratio of the amount of toner recovered by the developing member to the amount of toner supplied from the developing member to the image carrier during the toner ejection operation. The image forming apparatus according to claim 1, characterized in that the consumption acquisition unit acquires the toner consumption by multiplying the value relating to the toner amount by the correction coefficient.

3. The image forming apparatus according to claim 1 or 2, characterized in that the correction coefficient is a predetermined fixed value.

4. The image forming apparatus according to claim 1 or 2, characterized in that the correction coefficient is determined based on information regarding the degree of toner deterioration.

5. The image forming apparatus according to claim 4, characterized in that the information regarding the degree of deterioration of the toner is temperature information of the environment in which the image forming apparatus is installed.

6. The image forming apparatus according to claim 4, characterized in that the information regarding the degree of deterioration of the toner is the rotation distance of the developing member.

7. The image forming apparatus according to claim 4, characterized in that the information regarding the degree of deterioration of the toner is the saturated water vapor amount determined based on temperature information and humidity information of the environment in which the image forming apparatus is installed.

8. The image forming apparatus according to claim 4, characterized in that the information regarding the degree of deterioration of the toner is the average printing rate in the image forming operation.

9. A cartridge comprising the image carrier, the charging member, and the developing member, The cartridge includes a cartridge information storage unit that is mounted on the cartridge and stores the cartridge's unique information, Furthermore, The image forming apparatus according to claim 1 or 2, characterized in that the correction coefficient is determined based on a value stored in the cartridge information storage unit.

10. The image forming apparatus according to claim 9, characterized in that the control unit acquires the remaining amount of toner stored in the cartridge based on the consumption amount acquired by the consumption amount acquisition unit.

11. The transfer member further comprises contacting the intermediate transfer body, The image forming apparatus according to claim 1, characterized in that the control unit controls the charging voltage applied to the charging member, the exposure amount of the exposure apparatus, the developing voltage applied to the developing member, and the transfer voltage applied to the transfer member to control the surface potential of the image carrier.

12. The control unit, in the toner ejection operation, When the toner supplied to the image carrier first passes through the transfer portion, which is the contact portion between the image carrier and the intermediate transfer body, the transfer voltage is controlled to be negative and the absolute value of the transfer voltage is greater than the absolute value of the surface potential of the image carrier. The image forming apparatus according to claim 11, characterized in that the value of the transfer voltage is controlled to become positive when the toner remaining on the surface of the image carrier passes through the transfer section again.

Images