Image forming apparatus

Abstract

To provide an image forming apparatus that can improve the accuracy of calculating toner consumption.SOLUTION: An image forming apparatus comprises: a photoreceptor; a toner storage unit that stores toner; a developing member that carries the toner stored in the toner storage unit, supplies the toner to the photoreceptor, and develops a latent image on the photoreceptor into a toner image; a mounting unit on which a supply container storing the toner can be mounted, the mounting unit allowing execution of toner supply from the supply container to the toner storage unit, in a state in which at least part of the supply container is on the outside of the image forming apparatus; and a control unit that calculates toner consumption by multiplying a count value correlated to the number of pixels forming the toner image by a coefficient. When the toner supply is executed, the control unit changes the value of the coefficient.SELECTED DRAWING: Figure 10

Description

[Technical Field]

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

[0002] A known replenishment method (toner replenishment method, external replenishment method) uses a replenishment container to replenish toner from outside the image forming device to a toner storage section that stores toner as developer inside the image forming device. Patent Document 1 describes an image forming device that has a developer storage chamber and an attachment port to which a developer supply bottle can be detachably attached, and is configured so that when the developer supply bottle is attached to the attachment port, the developer in the bottle moves into the developer storage chamber by its own weight. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-86450 Summary of the Invention [Problem to be solved by the invention]

[0004] One method by which the control unit of an image forming device determines the amount of toner remaining in the toner storage unit is the dot count method (also called the pixel count method), which calculates the amount of toner consumed based on the number of pixels on which a toner image is formed. However, when toner is replenished, there have been cases where the amount of toner consumed calculated using the dot count method differs from the actual amount of toner consumed.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an image forming apparatus that can improve the accuracy of calculating the amount of toner consumption. [Means for solving the problem]

[0006] One aspect of the present invention is an image forming device comprising: a photosensitive body; a toner storage section that stores toner; a developing member that carries the toner stored in the toner storage section and supplies it to the photosensitive body, thereby developing the latent image on the photosensitive body into a toner image; an attachment section to which a supply container that stores toner can be attached, the attachment section allowing toner to be replenished from the supply container to the toner storage section while at least a portion of the supply container is outside the image forming device; and a control section that calculates the amount of toner consumed by multiplying a count value that correlates to the number of pixels that make up the toner image by a coefficient, wherein the control section changes the value of the coefficient when toner is replenished. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an image forming apparatus capable of improving the accuracy of calculating the amount of toner consumption. [Brief explanation of the drawings]

[0008] [Figure 1] 1A is a schematic diagram of an image forming apparatus according to a first embodiment, and FIG. 1B is a schematic diagram of an image forming apparatus equipped with a toner pack. [Figure 2] 3A and 3B are explanatory views of a developing container and a toner pack according to the first embodiment. [Figure 3] 3A and 3B are explanatory views of a developing container and a toner pack according to the first embodiment. [Figure 4] FIG. 2 is an explanatory diagram of a toner pack according to the first embodiment. [Figure 5] 3A to 3C are explanatory diagrams of toner packs according to the first embodiment and a modified example. [Figure 6] FIG. 2 is a block diagram showing a control configuration of the image forming apparatus according to the first embodiment. [Figure 7] 3A to 3C are explanatory diagrams of a remaining amount display panel according to the first embodiment. [Figure 8] 4 shows an example of a screen display of a remaining amount display unit according to the first embodiment. [Figure 9] 6A to 6C are graphs (a to c) showing an example of the transition of the remaining toner amount and the display of the remaining toner amount in Example 1. [Figure 10]3 is a flowchart showing a control method according to the first embodiment. [Figure 11] 10A and 10B are diagrams showing examples of control of charging voltage and developing voltage according to the second embodiment. [Figure 12] 10 is a graph showing an example of the transition of the remaining toner amount display in the second embodiment. [Figure 13] Graphs (a, b) showing an example of the transition of the remaining toner amount and the display of the remaining toner amount in Modification 1. [Figure 14] 10A is an explanatory diagram of density fluctuations of a halftone image in Modification 2, and FIG. 10B is a diagram showing a determination flow of the coefficient k. [Figure 15] Graphs (a) to (d) show an example of the transition of the remaining toner amount and the display of the remaining toner amount in Modification 2. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0010] Example 1 A first embodiment of the present disclosure will be described. FIG. 1(a) is a schematic diagram showing an image forming apparatus 100 according to the first embodiment. The image forming apparatus 100 is an electrophotographic monochrome laser beam printer. The image forming apparatus 100 forms an image on a recording material P based on image data (image information) input from an external computer. A variety of sheet materials of different sizes and materials can be used as the recording material P (recording medium), including paper such as plain paper and cardboard, surface-treated sheet materials such as coated paper, specially shaped sheet materials such as envelopes and index paper, plastic film, cloth, etc. The maximum size of recording material P on which the image forming apparatus 100 of this embodiment can form an image is letter size (215.9 mm) in the width direction perpendicular to the recording material transport direction.

[0011] 1(a), the image forming apparatus 100 includes an apparatus main body M, a process unit 9, an exposure device 10, a transfer roller 13, a fixing device 14, and a control unit 90. The apparatus main body M has a housing including a frame member that forms the frame of the apparatus main body M, and a cover member that forms the outer surface of the apparatus main body M. The process unit 9, the exposure device 10, the transfer roller 13, the fixing device 14, and the control unit 90 are attached to the apparatus main body M.

[0012] The process unit 9 may be fixed to the apparatus main body M in a manner that does not anticipate attachment or detachment by the user. Alternatively, the process unit 9 may be a unit (cartridge) that can be attached or detached to the apparatus main body M by the user.

[0013] The process unit 9 is a direct transfer type electrophotographic unit. The process unit 9 has a photosensitive drum 1 and at least one process means acting on the photosensitive drum 1. The process means is a unit or member for performing at least one of the steps of charging, exposing, developing, transferring, discharging, and cleaning in electrophotography. The process unit 9 of this embodiment has the photosensitive drum 1, a charging roller 2 as charging means, a developing device 20 as developing means, a discharging device 11 as discharging means, and a brush member 12.

[0014] The photosensitive drum 1 is a photoconductor (image carrier) that carries a latent image and a toner image. The photosensitive drum 1 is cylindrical (drum-shaped) and rotatable about a rotation axis CP. In this embodiment, the photosensitive drum 1 has a photosensitive layer formed of a negatively charged organic photoconductor on a drum-shaped aluminum substrate. More specifically, the photosensitive drum 1 is a rigid member constructed by sequentially applying a resistive layer, an undercoat layer, and a photosensitive layer to the outer surface of an aluminum cylinder with a diameter of 24 mm using a dip coating method. The photosensitive layer includes a charge generation layer and a charge transport layer. The charge transport layer has a film thickness of 22 μm. During image formation, the photosensitive drum 1 is driven to rotate at a predetermined peripheral speed around the rotation axis CP in the direction of arrow L by a motor M1 (FIG. 6) located within the apparatus main body M. The peripheral speed of the photosensitive drum 1 determines the speed of image formation by the image forming apparatus 100, and is therefore also referred to as the process speed.

[0015] The charging roller 2, which serves as a charging member, contacts the photosensitive drum 1 with a predetermined pressure to form a charging portion N2. A charging voltage is applied to the charging roller 2 from a charging voltage application circuit 71 (FIG. 6), thereby uniformly charging the surface 1a of the photosensitive drum 1 to a predetermined potential. The surface 1a of the photosensitive drum 1 is charged by the charging roller 2 to a pre-exposure potential VD, which is the same polarity as the normal polarity of the toner (negative in this embodiment). A DC voltage of -1400 V, for example, is applied to the charging roller 2 in this embodiment as a charging voltage, thereby charging the surface potential (pre-exposure potential VD) of the photosensitive drum 1 to -800 V.

[0016] An example of the charging roller 2 has a core metal with a diameter of 6 mm, a base layer of hydrin rubber, and a surface layer of urethane, and is formed to have an outer diameter of 12 mm. The resistance of the charging roller 2 is, for example, 1×10 6 Ω or less. The hardness of the charging roller 2 is, for example, 70 degrees as measured by an MD-1 rubber hardness tester. Although the charging voltage in this embodiment is a DC voltage, it may also be a voltage in which an AC voltage is superimposed on a DC voltage.

[0017] The exposure device 10 is an exposure means that exposes the photosensitive drum 1. The exposure device 10 in this embodiment is a laser scanner unit. That is, the exposure device 10 includes a light source 10a that emits laser light and a scanning optical system (polygon mirror, fθ lens, etc.) that guides the laser light from the light source 10a to the photosensitive drum 1 and scans the surface 1a of the photosensitive drum 1 with the laser light. The light source 10a is a semiconductor laser that emits laser light with a wavelength of, for example, 800 nm. The light source 10a is also capable of changing the amount of laser light it outputs. Note that the exposure device 10 is not limited to a laser scanner unit, and may be, for example, an LED exposure device having an LED array as a light source, in which multiple LEDs are arranged along the rotational axis direction of the photosensitive drum 1.

[0018] The developing device 20 has a developing container 8, a developing roller 4, and a supply roller 5. The developing container 8 forms the frame of the developing device 20. The developing container 8 is also an example of a toner storage section that stores toner as a developer. Inside the developing container 8, a storage chamber 8a and a developing chamber 8b are formed as spaces for storing toner. The storage chamber 8a and the developing chamber 8b are connected to each other so as to allow the toner to move between them.

[0019] The developing roller 4 and the supply roller 5 are rotatably supported by a developer container 8. The developing roller 4 is a developing member (developer carrier) that carries and supplies toner to the photosensitive drum 1, developing the latent image on the photosensitive drum 1 into a toner image. The developing roller 4 is disposed at the opening of the developer container 8 so as to face the photosensitive drum 1. A developing section 21 is formed where the developing roller 4 and the photosensitive drum 1 face each other. The supply roller 5 abuts against the developing roller 4 and scrapes off toner remaining on the developing roller 4 without transferring to the photosensitive drum 1 at the developing section 21. The supply roller 5 also supplies toner contained in the developer container 8 to the surface of the developing roller 4. The rotation direction of the supply roller 5 may be a direction in which the surface of the developing roller 4 moves in the opposite direction to the surface of the supply roller 5 at the facing portion with the developing roller 4 (counter direction), or a direction in which the supply roller 5 rotates along with the developing roller 4 (with direction). In this embodiment, the supply roller 5 rotates in a counter direction relative to the developing roller 4.

[0020] The developing device 20 of this embodiment uses a contact development method. That is, a toner layer carried on the developing roller 4 comes into contact with the photosensitive drum 1 in the developing section 21. A developing voltage is applied to the developing roller 4 from a developing voltage application circuit 72 (FIG. 6). The developing voltage is, for example, a DC voltage of the same polarity as the normal polarity of the toner. Under the developing voltage, the toner carried on the developing roller 4 is transferred from the developing roller 4 to the surface 1a of the photosensitive drum 1 in accordance with the potential distribution on the surface 1a, thereby developing the electrostatic latent image into a toner image.

[0021] This embodiment employs a reversal development method. That is, after being charged in the charging process, the toner adheres to the surface area (exposed area / image area) of the photosensitive drum 1, where the charge amount is attenuated by exposure in the exposure process, and a toner image is developed. On the other hand, toner does not adhere to the surface area (non-exposed area / non-image area) of the photosensitive drum 1 that was not exposed in the exposure process, and a toner image is not developed.

[0022] An example of the developing roller 4 has a core metal with a diameter of 6 mm, a base layer formed of silicone rubber on the outer periphery of the core metal, and a surface layer formed of urethane rubber on the outer periphery of the base layer, and is formed to have an outer diameter of 15 mm. The resistance value of the developing roller 4 is, for example, 1×10 4 ~1×10 12 Ω. An example of the supply roller 5 is a conductive and elastic sponge roller having a core metal with a diameter of 6 mm and a conductive foam layer formed on the outer periphery of the core metal. The resistance value of the supply roller 5 is, for example, 1×10 4 ~1×10 8 The hardness of the supply roller 5 can be measured by measuring the load when a flat plate with a width of 50 mm in the direction of the rotation axis of the supply roller 5 is inserted 1 mm from the surface of the supply roller 5 toward the rotation axis, and in this embodiment, it is 200 gf.

[0023] An agitating member 7 is disposed inside the developing container 8. The agitating member 7 is driven to rotate by a motor M1, thereby agitating the toner inside the developing container 8. The agitating member 7 also sends the toner toward the developing roller 4 and the supply roller 5. The agitating member 7 also circulates the toner that has not been used for development and has been scraped off from the developing roller 4 inside the developing container 8, thereby serving to make the toner inside the developing container 8 uniform.

[0024] A developing blade 6 is disposed at the opening of the developing container 8 in which the developing roller 4 is disposed, and regulates the amount of toner carried by the developing roller 4. The toner supplied to the surface of the developing roller 4 is uniformly thinned into a thin layer as it passes through the opposing portion between the developing roller 4 and the developing blade 6 as the developing roller 4 rotates, and is charged to the normal polarity (negative polarity) by frictional charging.

[0025] An example of the developing blade 6 is a metal plate (for example, a stainless steel plate) having a thickness of 0.1 mm, and its base (fixed end) is supported by a support provided in the developing container 8. The developing blade 6 is positioned so that its tip abuts against the surface of the developing roller 4, with an inclined attitude such that the direction from the base (fixed end) to the tip (free end) faces upstream in the rotation direction of the developing roller 4. The developing blade 6 used in this embodiment is a sheet metal member obtained by cutting the tip of a stainless steel plate (SUS sheet metal) from the side of the surface that abuts against the developing roller 4. The tip portion of the developing blade 6 is bent in the cutting direction by the cutting process.

[0026] The transfer roller 13 as a transfer means is in contact with the photosensitive drum 1, forming a transfer portion N1 between the photosensitive drum 1 and the transfer roller 1. An example of the transfer roller 13 has a core metal with a diameter of 6 mm and a base layer of ion conductive sponge formed on the outer periphery of the core metal so as to have an outer diameter of 15 mm. The resistance value of the transfer roller 13 is, for example, 4×10 in an environment at a temperature of 22°C. 7 The hardness is 30 degrees as measured by an Asker C rubber hardness tester manufactured by Kobunshi Keiki Co., Ltd. The width of the outer peripheral surface of the transfer roller 13 in the direction of the rotation axis of the photosensitive drum 1 is approximately equal to letter size (8.5 inches = 215.9 mm).

[0027] The static eliminator 11, which eliminates static electricity from the surface 1a of the photosensitive drum 1, is provided downstream of the transfer section N1 and upstream of the charging section N2 in the rotation direction (direction of arrow L) of the photosensitive drum 1. More specifically, the static eliminator 11 is disposed between the brush member 12 and the charging roller 2 in the rotation direction of the photosensitive drum 1. The static eliminator 11 eliminates the surface potential of the photosensitive drum 1 before it reaches the charging section N2 in order to generate a stable discharge at the charging section N2.

[0028] The brush member 12 is supported by a support member (not shown) and is fixed in position. The brush member 12 rubs against the surface of the photosensitive drum 1 as the photosensitive drum 1 rotates. The brush member 12 collects paper dust transferred from the recording material P onto the photosensitive drum 1 at the transfer portion N1, and reduces the amount of paper dust that reaches the charging portion N2 and the developing portion 21, which are downstream of the brush member 12 in the rotation direction of the photosensitive drum 1.

[0029] The fixing device 14 is a thermal fixing device that fixes an image by heating and melting the toner on the recording material P. The fixing device 14 in this embodiment has a fixing film 14a as a heating member (fixing member), a heater as a heat source for heating the heating member, and a pressure roller 14b that contacts the fixing film 14a. The fixing film 14a is a flexible, cylindrical thin film. The heater is, for example, a ceramic heater with a heating resistor pattern printed on a ceramic substrate, and is disposed in the internal space of the fixing film 14a. The pressure roller 14b is disposed so as to sandwich the fixing film 14a together with the heater. A nip portion (fixing nip) is formed between the fixing film 14a and the pressure roller 14b.

[0030] The heating member may be, for example, a cylindrical fixing roller or an endless fixing belt stretched over multiple rollers.The heat source may be a halogen heater that emits radiant heat or a coil unit that generates heat through electromagnetic induction in a conductive layer in the heating member.

[0031] [Image formation operation] The following describes a series of operations (image forming operation, printing operation) in which image forming apparatus 100 forms an image on recording material P using toner while conveying recording material P. When an image formation command is output to image forming apparatus 100, image forming operation is started based on image data input from an external device connected to image forming apparatus 100.

[0032] In the image forming operation, the photosensitive drum 1 is driven by a motor M1 (FIG. 6) and rotated in the direction of arrow L in FIG. 1(a) at a predetermined rotation speed (140 rpm in this embodiment). The charging roller 2 uniformly charges the surface of the rotating photosensitive drum 1 so that the surface potential (pre-exposure potential VD) is -800 V. The exposure device 10 is driven by a video signal sent by the control unit 90 based on input image data, and irradiates the photosensitive drum 1 with a laser in accordance with the video signal. As a result, an electrostatic latent image is formed on the uniformly charged surface 1a of the photosensitive drum 1. In this embodiment, the exposure device 10 emits a light of 0.45 μJ / cm so that the post-exposure potential VL (light area potential) of the photosensitive drum 1 is -100 V. 2 The laser beam is irradiated.

[0033] A toner layer is formed on the surface of the developing roller 4 by toner charged to the normal polarity. When a developing voltage is applied to the developing roller 4, the toner is transferred from the developing roller 4 to the exposed area on the surface 1a of the photosensitive drum 1 in the developing unit 21. This develops the electrostatic latent image on the surface 1a of the photosensitive drum 1, and a toner image is formed on the surface 1a of the photosensitive drum 1. In this embodiment, a DC voltage of -400 V is applied to the developing roller 4 as the developing voltage.

[0034] In parallel with the above-described toner image forming process, a recording material P stored in a storage compartment at the bottom of the image forming apparatus 100 is fed by a feeding roller. The recording material P is transported to the transfer section N1 in accordance with the timing when the toner image formed on the photosensitive drum 1 reaches the transfer section N1. Also, a transfer voltage is applied to the transfer roller 13 in accordance with the timing when the toner image formed on the photosensitive drum 1 reaches the transfer section N1. As a result, the toner image carried on the photosensitive drum 1 is transferred to the recording material P passing through the transfer section N1. In this embodiment, a DC voltage of +1500 V is applied to the transfer roller 13 as the transfer voltage.

[0035] The recording material P onto which the toner image has been transferred is transported to the fixing device 14. The fixing device 14 heats and pressurizes the toner image on the recording material P while nipping and transporting the recording material P in a fixing nip, thereby fixing the toner image to the recording material P. After passing through the fixing device 14, the recording material P is discharged to the outside of the image forming apparatus 100 by a pair of discharge rollers and is stacked on a discharge tray provided on the top surface of the apparatus main body M.

[0036] In this embodiment, the transfer residual toner that is not transferred to the recording material P at the transfer portion N1 and remains on the photosensitive drum 1 is collected into the developer container 8 by the developing roller 4. In other words, this embodiment employs a so-called cleanerless configuration (simultaneous development and cleaning configuration) in which the toner that is not transferred to the recording material P, which is the transfer target, at the transfer portion N1 is collected into a toner storage portion by a developing member.

[0037] After the transfer process, the surface area of ​​the photosensitive drum 1 receives a transfer current when passing through the transfer section N1, resulting in a reduced surface potential. In this embodiment, the surface potential (potential of the non-exposed area) of the photosensitive drum 1 after the transfer process is −150 V. The surface area of ​​the photosensitive drum 1 after the transfer process is neutralized by the neutralization device 11 so that the remaining surface potential becomes 0 V, and the photosensitive drum 1 moves toward the charging section N2.

[0038] The residual toner after transfer is a mixture of positively charged toner and negatively charged toner that does not have a sufficient charge. The photosensitive drum 1 after transfer is neutralized by the static eliminator 11, and uniform discharge is caused by the charging roller 2, so that the residual toner can be charged negatively again. The residual toner that has been negatively charged again at the charging unit N2 reaches the developing unit 21 as the photosensitive drum 1 rotates, and is collected into the developer container 8 by the developing roller 4.

[0039] That is, the potential of the developing roller 4 (DC component of the developing voltage, −400 V) is positive with respect to the surface potential of the non-exposed region of the photosensitive drum 1 (pre-exposure potential VD, −800 V), and negative with respect to the surface potential of the exposed region of the photosensitive drum 1 (post-exposure potential VL, −100 V). Therefore, the transfer residual toner adhering to the non-exposed region of the photosensitive drum 1 when it reaches the developing unit 21 is transferred from the photosensitive drum 1 to the developing roller 4 in the developing unit 21 and is collected in the developer container 8. On the other hand, the transfer residual toner adhering to the exposed region of the photosensitive drum 1 when it reaches the developing unit 21 does not transfer to the developing roller 4 in the developing unit 21, but remains on the photosensitive drum 1, and forms a toner image together with newly supplied toner from the developing roller 4.

[0040] As described above, in this embodiment, the process unit 9 has a cleaner-less configuration in which the transfer residual toner is collected and reused in the developing device 20. By configuring the process unit 9 as a cleaner-less configuration, there is no need for installation space for a collection container for collecting the transfer residual toner, etc., making it possible to further reduce the size of the image forming apparatus 100. Furthermore, by reusing the transfer residual toner, the toner consumption rate can be suppressed, which also helps reduce printing costs.

[0041] [toner] In this embodiment, a toner having a particle size of 6 μm and a normal polarity (normal charging polarity) of negative polarity is used. The toner in this embodiment is, for example, a polymerized toner produced by suspension polymerization. The toner in this embodiment does not contain a magnetic component and is a so-called non-magnetic one-component developer that is supported on the developing roller 4 mainly by intermolecular forces and electrostatic forces (image forces). However, a one-component developer containing a magnetic component may also be used as the developer (toner). In addition to the toner particles, the one-component developer may contain additives (e.g., wax or silica particles) to adjust the fluidity and charging performance of the toner. Alternatively, the toner may contain an organosilicon polymer having a unit structure represented by the following formula (1) on the surface of the toner particles: R-SiO 3 / 2 (1) In formula (1), R is an alkyl group having 1 to 6 carbon atoms, or a phenyl group. By including this organosilicon polymer, convex portions are formed on the surface of the toner particles, improving the performance of the toner.

[0042] Alternatively, a two-component developer containing a non-magnetic toner and a magnetic carrier may be used as the developer. When a magnetic developer is used, a cylindrical developing sleeve with a magnet disposed inside is used as the developer carrier. The developing device 20 may also be a non-contact developing device, in which a predetermined gap is maintained between the developing device 20 and the photosensitive drum 1.

[0043] [Developer container and toner pack] Next, the developing container 8 and the toner pack 40 serving as a supply container in this embodiment will be described. Fig. 2(a) is a perspective view showing the process unit 9 including the developing container 8 and the toner pack 40, and Fig. 2(b) is a front view showing the process unit 9 and the toner pack 40. Fig. 3(a) is a cross-sectional view taken along line 40A-40A in Fig. 2(b), and Fig. 3(b) is a cross-sectional view taken along line 40B-40B in Fig. 2(b).

[0044] 2(a)(b) and 3(a)(b), the storage chamber 8a of the developer container 8 extends over substantially the entire length of the developer container 8 in the longitudinal direction of the developing device 20 (the direction of the rotational axis of the developing roller 4). The developer container 8 also has a protruding portion 37 that protrudes upward from one end of the storage chamber 8a in the longitudinal direction and communicates with the storage chamber 8a.

[0045] An attachment portion 57 is provided at the upper end (tip) of the protruding portion 37, to which the toner pack 40 can be attached. The attachment portion 57 is formed with a supply port 32a that enables toner to be replenished from the toner pack 40 to the storage chamber 8a. When the toner pack 40 is attached to the attachment portion 57, the internal space of the toner pack 40 communicates with the storage chamber 8a inside the developing container 8 through the supply port 32a, allowing toner to move from the toner pack 40 to the storage chamber 8a.

[0046] The toner pack 40 is attached to the attachment portion 57 with at least a portion of the toner pack 40 exposed to the outside of the image forming apparatus 100 (see FIG. 1(b)). A user can expose the attachment portion 57 by, for example, opening an opening / closing member 101 provided on the top surface of the apparatus main body M, and then attach the toner pack 40 to the attachment portion 57. When the opening / closing member 101 is closed, the attachment portion 57 is covered by the opening / closing member 101. In other words, the attachment portion 57 is configured to allow toner to be replenished from the toner pack 40 to the developing container 8 with at least a portion of the toner pack 40 located outside the image forming apparatus 100.

[0047] The developing container 8 is configured so that toner introduced into the supply port 32a can reach the agitator 7 by its own weight alone. Here, "by its own weight alone" means that the toner moves along the path from the supply port 32a to the agitator 7 mainly by the action of gravity, without receiving force from a toner transport member (such as a screw) that receives driving force from a drive source such as a motor. The agitator 7 is the rotating body closest to the supply port 32a, and is arranged so that by rotating it sends the toner in the storage chamber 8a toward the developing roller 4 or the supply roller 5.

[0048] The developing container 8 has a handle portion 39 (FIGS. 2(a) and 2(b)). The handle portion 39 has a knob portion 39a that a user can grip by hooking their fingers. The knob portion 39a is formed so as to protrude upward from the top surface of the handle portion 39.

[0049] The protrusion 37 is hollow and has a supply port 32a formed on the top surface thereof. The supply port 32a is configured to be connectable to the toner pack 40.

[0050] The toner pack 40 is detachably attached to a mounting portion 57 provided on the protruding portion 37. The toner pack 40 also has a shutter member 41 that can open and close an outlet of the main body of the toner pack 40, and a plurality of (three in this embodiment) protrusions 42 formed in correspondence with a plurality of (three in this embodiment) grooves 32b formed in the mounting portion 57. When replenishing toner into the developing container 8, the user aligns the plurality of protrusions 42 of the toner pack 40 so that they pass through the plurality of grooves 32b of the mounting portion 57, and then mounts the toner pack 40 in the mounting portion 57.

[0051] When the toner pack 40 attached to the attachment portion 57 is rotated 180 degrees, the shutter member 41 of the toner pack 40 abuts against an abutment portion (not shown) of the attachment portion 57, causing the shutter member 41 to rotate relative to the main body of the toner pack 40 and move from the closed position to the open position. The closed position is a position where the shutter member 41 closes the discharge port, and the open position is a position where the shutter member 41 is retracted so as to open the discharge port. This connects the discharge port and the supply port 32a, and the toner stored inside the toner pack 40 flows down into the protrusion 37 via the discharge port and the supply port 32a. The shutter member 41 may also be provided on the supply port 32a side (the side of the device main body M).

[0052] The protrusion 37 has a slope 37a at a position facing the supply port 32a in the vertical direction (a position below the supply port 32a). The slope 37a is inclined downward in a direction approaching the storage chamber 8a (a direction approaching the rotation axis of the stirring member 7). Therefore, the toner supplied to the developer container 8 through the supply port 32a is guided into the storage chamber 8a by the slope 37a.

[0053] 3(a) and 3(b), the agitating member 7 has an agitating shaft 7a extending in the longitudinal direction of the developing device 20 and blade portions 7b fixed to the agitating shaft 7a and protruding radially outward from the agitating shaft 7a. The blade portions 7b are flexible sheets. The agitating member 7 rotates around the agitating shaft 7a.

[0054] Toner supplied from the supply port 32a, which is located upstream of the agitator 7 in the conveying direction, is sent toward the developing roller 4 and the supply roller 5 as the agitator 7 rotates. When viewed in the longitudinal direction of the developing device 20 (the direction of the rotation axis of the developing roller 4), the agitator 7 conveys toner from the supply port 32a toward the developing roller 4. The agitator 7 can also convey toner in the longitudinal direction. The supply port 32a and the protrusion 37 are located at one end of the developer container 8 in the longitudinal direction, but repeated rotation of the agitator 7 distributes toner throughout the entire developer container 8 in the longitudinal direction. Note that instead of the agitator 7 having the agitator shaft 7a and the blade portion 7b, a spiral agitator (screw or coil spring), for example, may be used to convey toner.

[0055] As shown in Figures 4 and 5(a), the toner pack 40 serving as a supply container in this embodiment has a toner storage portion formed of an easily deformable plastic bag. However, the supply container is not limited to this, and may be, for example, a substantially cylindrical bottle container 40B shown in Figure 5(b) or a paper container 40C made of paper shown in Figure 5(c). There are no particular limitations on the material and shape of the supply container.

[0056] Furthermore, the method of discharging toner from the toner pack is preferably for the user to squeeze the toner pack 40 or paper container 40C with their fingers, and for the bottle container 40B, it is preferably for the user to shake the container by tapping it or the like to cause the toner to leak. Furthermore, to discharge toner from the bottle container 40B, a discharge mechanism may be provided within the bottle container 40B, which allows the toner to be discharged without relying on the toner's own weight. The discharge mechanism may be a piston that slides against a cylindrical portion (cylinder portion) of the bottle container 40B. Furthermore, the discharge mechanism may be configured to engage with the device main body M and receive a driving force from the device main body M.

[0057] Furthermore, the shutter member 41 may be omitted from any of the supply containers (40, 40B, 40C), and a sliding shutter member may be used instead of the rotating shutter member 41. Furthermore, the shutter member 41 (sealing member) may be configured to be destroyed when the supply container is attached to the attachment portion 57 or when the toner pack is rotated while attached, or may have a removable lid structure such as a seal.

[0058] As described above, this embodiment employs a toner supply system that enables toner to be supplied to the developing container 8 (toner storage unit) inside the image forming apparatus 100 from outside the apparatus using a toner pack 40. With the cartridge system, every time the toner runs out, the toner cartridge that stores the toner, the developing device 20 (developing cartridge) having the developing roller 4, or the process unit 9 (process cartridge) having the photosensitive drum 1 and the developing roller 4 are all replaced. In contrast, with the toner supply system, it is only necessary to supply toner into the developing container 8, and this system can reduce the environmental impact compared to the cartridge system.

[0059] [Image forming device control system] 6 is a block diagram showing a control system of image forming apparatus 100. Image forming apparatus 100 has a control unit 90 as a control means for controlling the operation of image forming apparatus 100. Control unit 90 has a CPU 91 as a calculation unit, a RAM 92 used as a work area for CPU 91, and a ROM 93 for storing various programs. Control unit 90 also has an I / O interface 94 as an input / output port for connecting to external devices.

[0060] An attachment sensor 53 is connected to the input side of the control unit 90. The attachment sensor 53 is an example of a detection means for detecting attachment and detachment (at least one of attachment and detachment) of the toner pack 40 to and from the attachment unit 57. The attachment sensor 53 is, for example, a pressure-sensitive switch that is provided in the supply port 32a and outputs a detection signal when pressed by the protrusion 42 of the toner pack 40. Based on the detection signal from the attachment sensor 53, the control unit 90 can determine that toner replenishment has been performed when it detects that the toner pack 40 has been removed after being attached.

[0061] The control unit 90 is also connected to an operation unit 300, the image forming unit 60, a remaining amount display unit 400, and a power supply board 70. The operation unit 300 (operation panel) has a display unit 301, such as a liquid crystal panel, capable of displaying various setting screens, and an input unit, such as a touch panel function of the display unit 301 or physical keys. The image forming unit 60 has a motor M1 as a drive source and an exposure device 10. In this embodiment, the motor M1 is a common drive source for the photosensitive drum 1, the developing roller 4, the supply roller 5, and the agitating member 7. Note that the photosensitive drum 1, the developing roller 4, the supply roller 5, and the agitating member 7 may each be driven by a separate motor. The exposure device 10 performs an exposure process by irradiating the photosensitive drum 1 with laser light modulated based on a video signal sent from the control unit 90.

[0062] The power supply board 70 is connected to an external commercial power source and supplies power to drive the control unit 90, motor M1, etc., and outputs a high voltage to be applied to the charging roller 2, developing roller 4, transfer roller 13, etc. The power supply board 70 includes a charging voltage application circuit 71 (first voltage application unit) that applies a charging voltage (first voltage) to the charging roller 2, and a developing voltage application circuit 72 (second voltage application unit) that applies a developing voltage (second voltage) to the developing roller 4.

[0063] The remaining amount display unit 400 is a display unit that displays information (remaining amount information) regarding the remaining amount of toner in the developing container 8 (toner storage unit). FIGS. 7(a) to 7(c) show a remaining amount display panel 401 as an example of the remaining amount display unit 400. The remaining amount display panel 401 includes a plurality of lamps (three in this embodiment) 401a, 401b, and 401c. The remaining amount display panel 401 is disposed, for example, on the front surface of the apparatus main body M (the surface on the downstream side in the direction in which the recording material is discharged from the apparatus main body M). The remaining amount display panel 401 displays the remaining amount information of toner depending on whether or not the plurality of lamps 401a to 401c are lit, or the lighting state thereof.

[0064] The remaining amount display panel 401 of this embodiment functions as a scale (indicator) in which the number of lit lamps increases or decreases according to the amount of toner remaining in the developer container 8. The lamp 401c in the lower row corresponds to the lowest remaining toner level (Low level) among the multiple remaining toner levels that can be displayed by the remaining amount display panel 401. The lamp 401b in the middle row corresponds to a medium remaining toner level (Mid level), and the lamp 401a in the upper row corresponds to the highest remaining toner level (Full level).

[0065] That is, when the amount of toner remaining in the developing container 8 is equal to or less than the first threshold, only the lower lamp 401c is lit, and the other lamps 401a and 401b are turned off, as shown in Fig. 7(a). This display state indicates that the toner in the developing container 8 will soon run out (near empty), or that toner can be replenished. The control unit 90 can execute an operation of notifying the user of information urging the user to replenish toner (toner replenishment notification) by, for example, setting the remaining amount display panel 401 to the display state shown in Fig. 7(a).

[0066] When the amount of toner remaining in the developing container 8 is equal to or greater than a second threshold value that is greater than the first threshold value, all of the lamps 401a to 401c are lit, as shown in FIG. 7(c). This display state indicates that the current amount of toner remaining is 100% or close to 100% (full state) relative to the amount of toner that can be accommodated in the developing container 8. When the amount of toner remaining in the developing container 8 is greater than the first threshold value and less than the second threshold value, the lower and middle lamps 401b and 401c are lit, and the upper lamp 401a is turned off, as shown in FIG. 7(b). This display state indicates that the toner in the developing container 8 is between a near-empty state and a full state.

[0067] The specific configuration of remaining battery level display panel 401 and the display mode of remaining battery level information are not limited to those described above. The number of lamps may be one, two, or four or more. The lighting modes that each lamp can take are not limited to on and off, but may also be a combination of blinking, changes in light intensity, changes in light color, etc.

[0068] Furthermore, remaining amount display unit 400 is not limited to remaining amount display panel 401 using a lamp, and may display information regarding the remaining amount of toner by a screen display (image) as shown in Fig. 8. In this case, remaining amount display unit 400 may be operation unit 300 (operation panel) of image forming apparatus 100, or may be an external device (such as a user's personal computer) connected to image forming apparatus 100 so as to be able to communicate with it.

[0069] The screen display in FIG. 8 includes remaining toner information indicating the amount of toner remaining in the developer container 8, including a bar-shaped gauge G1 that changes continuously from 0% to 100% and a numerical value G2 (63%) representing the remaining toner amount. In the illustrated example, the remaining toner amount indicates 63%. That is, in this embodiment, the remaining toner amount changes from 100% to 0% as toner is consumed. The remaining toner amount information displayed on the screen by the remaining toner amount display unit 400 is not limited to this, and only either the gauge G1 or the numerical value G2 may be displayed. Alternatively, for example, an image that changes gradually depending on the remaining toner amount level may be used instead of the gauge G1. The control unit 90 can also execute a toner replenishment notification using the operation unit 300. The information displayed on the display unit 301 of the operation unit 300 for toner replenishment notification may be, for example, a text message, a voice message, or a buzzer sound. Alternatively, the toner amount may change continuously from 0% to 100% based on the amount of toner used (toner consumption).

[0070] [Dot count method] The control unit 90 of this embodiment uses a dot count method (pixel count method) to calculate the amount of toner consumed and the amount of toner remaining in the developing container 8. The dot count method is a method for calculating the amount of toner consumed during image formation and the amount of toner remaining after image formation, based on a count value (hereinafter referred to as the dot count value) corresponding to the number of pixels that make up an image formed on the recording material P.

[0071] As a mechanism by which the control unit 90 of the image forming apparatus 100 grasps the remaining toner amount, there is a dot counting method in which the remaining toner amount is calculated by software, as well as a method that uses a sensor to detect the remaining toner amount (sensor method, hardware detection method). Types of sensors include optical detection method, capacitance method, weight method, etc. The dot counting method is superior to the sensor method in that it is less expensive, there are no restrictions on hardware configuration, and the calculation accuracy does not depend on the amount of remaining toner.

[0072] Here, the control unit 90 performs image processing to analyze image data received from outside and develop it into a raster image, which is data in raster format. Based on the developed raster image, the control unit 90 transmits a video signal, which is a time-series signal that specifies whether or not to expose each pixel and the amount of light during exposure, to the exposure device 10. The exposure device 10 exposes or does not expose an area corresponding to each pixel on the photosensitive drum 1 with the amount of light corresponding to the value of the video signal.

[0073] The dot count value may be calculated using data or signals at any stage in the image forming operation, as long as the value correlates with the number of pixels that make up the image formed on the recording material P. In this embodiment, based on the raster image developed by the control unit 90, the number of dots that make up the raster image (the number of pixels to develop a toner image; the number of print pixels) is set as the dot count value.

[0074] However, the dot count value may be a numerical value representing the cumulative number of times light is emitted or the cumulative light emission time of the light source 10a in the exposure apparatus 10. For example, the dot count value may be the count result of a counter (counting circuit) that monitors the light emission of the laser element, which is the light source 10a of the exposure apparatus 10 in this embodiment, and counts the number of pixels at which the laser element emits light. The counter may be provided on a semiconductor substrate that drives the laser element (i.e., as part of the exposure apparatus 10). Alternatively, the counter may be provided in the control unit 90 and calculate an integrated value of the value of the video signal sent to the exposure apparatus 10. Alternatively, the dot count value may be a value obtained by measuring the cumulative light emission time of the laser element.

[0075] The dot count value may be counted as two values ​​per pixel: "0 (toner image not developed)" or "1 (toner image developed)," or the maximum count per pixel may be allowed to be greater than 1. For example, if the exposure light amount for one pixel is controlled in five steps of 20% from 0% to 100% by turning the light source 10a on and off for each of the four regions of a pixel, the count per pixel is set to five steps of 1 from "0" to "4." In this case, the maximum dot count value when one image is printed is four times the number of pixels in the effective image area (the maximum area where a toner image can be formed on the photosensitive drum 1). Also, for example, the count per pixel may be allowed to be a decimal.

[0076] Furthermore, the dot count value may be a value obtained by sampling and counting a portion of the data to be counted (the number of dots in a raster image or the cumulative number of times light is emitted by the light source 10a) in order to reduce the processing load, for example. In other words, the dot count value does not need to strictly match the number of pixels that make up the image to be formed on the recording material P, as long as it is calculated as a numerical value that correlates with the number of pixels that make up the image to be formed on the recording material P.

[0077] In this embodiment, the control unit 90 can calculate the dot count value. However, the counting circuit that calculates the dot count value may be disposed in a circuit separate from the control unit 90.

[0078] [Toner Level and Toner Level Display] 9(a) and 9(b) are used to explain the relationship between the remaining toner amount in the developer container 8 and the toner remaining amount display when a predetermined image is repeatedly printed using the image forming apparatus 100 of this embodiment. The horizontal axis of the graph in FIG. 9(a) represents the number of prints, and the vertical axis represents the remaining toner amount Q (g) in the developer container 8. Test images were repeatedly printed based on test image data with a 4% print coverage, which mixed halftone and text. The dot count value for each image formation operation is assumed to be constant. In the graph, Qfull represents the remaining toner amount Q immediately after toner replenishment, and Qout represents the predetermined threshold value of the remaining toner amount Q at which toner replenishment to the developer container 8 should be initiated. For example, when the remaining toner amount is displayed using a continuous gauge as shown in FIG. 8, "100%" is displayed when Q=Qfull, and "0%" is displayed when Q=Qout. As mentioned above, the remaining toner amount display may be a step-by-step display as shown in FIGS. 7(a) to 7(c).

[0079] The dot count value per test image is C, the amount of toner consumed when printing one test image is T (g), and the coefficient used to calculate the amount of toner consumed T is k. The control unit 90 of this embodiment calculates T using the following equation (2). T=k C (2)

[0080] The above formula (2) is an example of a function (T=f(C)) that expresses the toner consumption amount T using the dot count value C as a variable. The function f(C) may be different from formula (2).

[0081] The control unit 90 subtracts the toner consumption amount T from the value of the remaining toner amount Q each time a test image is printed from the state where Q=Qfull. When the remaining toner amount Q falls below Qout, the control unit 90 sets the display on the remaining amount display unit 400 to 0%, stops accepting any further image forming operations, and notifies the user to replenish toner. Hereinafter, the point at which the remaining toner amount Q reaches Qout will be referred to as "just before toner replenishment," and the point at which toner replenishment is performed from the state just before toner replenishment and the remaining toner amount Q reaches Qfull will be referred to as "just after toner replenishment."

[0082] In this embodiment, the value of the coefficient k is changed when toner is replenished as a measure to deal with the change in the pace of toner consumption due to toner replenishment. A change in the pace of toner consumption means that the amount of toner consumed T differs when an image is formed based on the same image data (i.e., when the dot count value C for one image is the same) immediately before and after toner replenishment.

[0083] The reason why the pace of toner consumption changes depending on toner replenishment can be explained as follows: When the toner of this embodiment is unused (fresh), there are many charge sites on the toner surface and the toner has high charging performance. The charge sites are mainly formed by additives (external additives) such as silica added to the toner.

[0084] On the other hand, the toner in the developer container 8 immediately before toner replenishment is in a state where it has been repeatedly used in image formation operations until the remaining toner amount Q decreases from Qfull to Qout. During image formation, the toner in the developer container 8 is carried by the developing roller 4 and rubs against the developing blade 6, photosensitive drum 1, and supply roller 5. Furthermore, the toner in the developer container 8 rubs against each other as the agitating member 7 rotates. For this reason, the toner in the developer container 8 immediately before toner replenishment contains a high proportion of toner particles whose charging performance has decreased due to additives being embedded in the toner surface or migrating from the toner surface to other components.

[0085] When toner with a high proportion of toner particles in a state where the charging performance has deteriorated (referred to as deteriorated toner) is mixed with newly replenished toner with high charging performance (referred to as fresh toner), charge transfer occurs between the fresh toner and the deteriorated toner due to the difference in charging performance. For this reason, the fresh toner tends to have a higher charge amount than when it is not mixed with the deteriorated toner, and the deteriorated toner tends to have a lower charge amount than when it is not mixed with the fresh toner. Also, the fresh toner has higher fluidity than the deteriorated toner and has a property of being more easily carried on the developing roller 4 than the deteriorated toner. As a result, the average charge amount of the toner carried on the developing roller 4 immediately after toner replenishment is larger than the average charge amount of the toner carried on the developing roller 4 immediately before toner replenishment. In other words, the absolute value of the average charge amount of the toner carried on the developing member after toner replenishment is larger than the average charge amount of the toner carried on the developing member before toner replenishment.

[0086] Since the charge amount of the toner on the developing roller 4 is larger after toner replenishment than before toner replenishment, the amount of toner required to fill the potential (post-exposure potential) of the electrostatic latent image on the photosensitive drum 1 in the state after toner replenishment is less than before toner replenishment. As a result, even if an image is formed based on the same image data before and after toner replenishment, the toner consumption amount T per sheet of the image after toner replenishment is less than the toner consumption amount T per sheet of the image before toner replenishment.

[0087] Therefore, in this embodiment, when toner replenishment is performed, the value of the coefficient k for calculating the toner consumption amount T based on the dot count value C is changed to a value smaller than before toner replenishment.

[0088] That is, the value k1 of the coefficient k after the first toner replenishment and before the second toner replenishment is smaller than the value k0 of the coefficient k before the first toner replenishment (k1 < k0). Similarly, based on the installation time point of the image forming apparatus, the value of the coefficient k after the Nth toner replenishment and before the (N + 1)th toner replenishment is k nThe value of the coefficient k after the N-1th toner supply and before the Nth toner supply is k n-1 In this case, k n <k n-1 That is, in this embodiment, the value of the coefficient k is decreased every time toner is replenished. In this embodiment, the value of the coefficient k is, for example, the ratio k of the values ​​of the coefficient k before and after toner replenishment. n / k n-1 is set to be within the range of 0.5 to 0.95.

[0089] In other words, when image forming operations are repeatedly performed based on the same image data (dot count value C is constant), the control unit 90 changes the value of the coefficient k when toner is replenished so that the calculated result of the toner consumption in the image forming operation after toner replenishment is less than the calculated result of the toner consumption in the image forming operation after toner replenishment.

[0090] Fig. 9(b) is a graph showing an example of changes in the remaining toner amount display in Example 1. Fig. 9(b) shows the relationship between the number of prints and the remaining toner amount display when the same test image as Fig. 9(a) is repeatedly printed.

[0091] As described above, in the first embodiment, the value of the coefficient k is reduced when toner is replenished. As a result, the value calculated as the toner consumption amount T per test image after the Nth toner replenishment is less than the value calculated as the toner consumption amount T per test image before the Nth toner replenishment. In other words, in FIG. 9(b), the slope D of the graph after the Nth toner replenishment is n is the slope D of the graph before the Nth toner replenishment n-1 It will be slower than

[0092] Therefore, the value of toner consumption amount T calculated based on the dot count value C can be made closer to the actual toner consumption amount. Also, the remaining toner amount (FIG. 9(b)) calculated based on toner consumption amount T calculated based on the dot count value C can be made closer to the actual remaining toner amount Q (FIG. 9(a)). Also, the timing when the actual remaining toner amount Q decreases to Qout and the timing when the calculated remaining toner amount decreases to Qout (the timing when the remaining toner amount display reaches 0%) become closer. Therefore, the user can be notified of the need for toner replenishment at a more appropriate timing.

[0093] In this embodiment, the value of coefficient k is decreased each time toner is replenished. Therefore, if test images are continued to be printed after the (N+1)th toner replenishment in FIG. 9(b), the relationship between the number of prints and the displayed remaining toner amount will be as shown in FIG. 9(c). In other words, each time toner is replenished, the value calculated as the toner consumption amount T per test image decreases, and the slope of the graph becomes gentler.

[0094] In addition, the number of prints from the Nth toner supply to the N+1th toner supply is P n So,... <P n-1 <P n <P n+1 <P n+2 <... In other words, when image formation operations based on the same image data are repeatedly performed, the more frequently toner is replenished, the greater the number of printed sheets between the previous toner replenishment and the next toner replenishment (the longer the interval between toner replenishments).

[0095] (Comparative Example 1) As Comparative Example 1, we will assume a case where the toner consumption amount T and the remaining toner amount Q are calculated without changing the value of coefficient k even when toner is replenished. The configuration of the device and the method of calculating the toner consumption amount T and the remaining toner amount Q are the same as in Example 1, except that the value of coefficient k after the Nth toner replenishment is the same as before toner replenishment. Therefore, as shown in Figure 9(a), the change in the actual remaining toner amount Q when the above-mentioned test image is repeatedly output is consistent with Example 1.

[0096] On the other hand, in Comparative Example 1, the toner consumption amount T per test image calculated based on the dot count value C does not change before and after the Nth toner replenishment. Therefore, as shown by the dashed line in FIG. 9(b), the slope D of the graph after the Nth toner replenishment n ' is the slope D of the graph before the Nth toner replenishment n-1 The slope D of the graph after the Nth toner supply in Example 1 is the same as n is relatively steeper than

[0097] As a result, the number of prints Pb at which the remaining toner amount Q calculated in Comparative Example 1 becomes 0% is less than the number of prints Pa at which the remaining toner amount Q becomes 0% calculated in Example 1. In other words, in Comparative Example 1, even though there is actually more toner remaining in the developer container 8 than Qout at the time of the number of prints Pb, a toner replenishment notification is issued. In contrast, according to this example, it is possible to issue a toner replenishment notification at or near the time of the number of prints Pa at which the actual remaining toner amount Q in the developer container 8 becomes equal to or less than Qout.

[0098] (Control method) A flowchart illustrating an example of a control method according to this embodiment is shown in Fig. 10. Each step of this flowchart is implemented by the CPU 91 of the control unit 90 reading and executing a program from the ROM 93. This flowchart is continuously processed while the main power of the image forming apparatus 100 is ON.

[0099] Each time an image forming operation is performed (S1 Yes), the control unit 90 acquires a dot count value C of the image to be formed in the image forming operation (S2). Based on the acquired dot count value C, the control unit 90 calculates the amount of toner consumed to form the image, T, and calculates the amount of toner remaining in the developer container 8 after the image forming operation is performed (S3). Specifically, the calculated amount of toner consumed T in this embodiment is a value obtained by multiplying the dot count value C by a coefficient k, and the amount of toner remaining Q after the image forming operation is performed is a value obtained by subtracting the amount of toner consumed T from the amount of toner remaining Q before the image forming operation is performed.

[0100] If the remaining toner amount Q after the image forming operation is equal to or less than a preset threshold (Qout) (S4 Yes), the control unit 90 does not accept a new image forming operation and issues a toner replenishment notification, prompting the user to replenish toner (S5). If the control unit 90 subsequently detects that toner replenishment has been performed (S6 Yes), it changes the value of the coefficient k (S7) and returns to the beginning to wait for the next image forming instruction. In this embodiment, toner replenishment is determined to have occurred when the control unit 90 detects, based on the detection signal from the installation sensor 53, that the toner pack 40 has been installed in the installation unit 57 and then removed. On the other hand, if the remaining toner amount Q after the image forming operation is greater than the threshold (Qout) (S4 No), the control unit 90 waits for the next image forming instruction without issuing a toner replenishment notification or changing the value of the coefficient k.

[0101] The value of the coefficient k after the Nth toner supply is k n (n=1, 2, 3, ...). In this embodiment, each k n The value of k is determined in advance in accordance with, for example, the specific manufacturing method of the toner and the specific configuration of the developing device 20, and is stored in the ROM 93 (FIG. 6) as a preset value. The CPU 91 counts up the number of toner replenishments each time toner is replenished, and calculates k according to the number of toner replenishments up to now. n The value is read from the ROM 93 and used to calculate the toner consumption amount T in the next and subsequent image forming operations.

[0102] The value of coefficient k may be calculated as needed depending on the toner consumption pattern between toner replenishment and the next toner replenishment. The toner consumption pattern may be, for example, the relationship between the average print rate (the average print rate of images output from the previous toner replenishment to the present) and the degree of toner deterioration. For example, when the average print rate is high, toner is consumed faster than the toner deterioration, so a toner replenishment notification will be issued early even when the toner deterioration is not very advanced. In such cases, the value of coefficient k may not be changed when toner is replenished, or the change amount may be smaller than when the average print rate is low.

[0103] (Summary of this Example) As described above, in this embodiment, when toner is replenished, the value of coefficient k used in calculating toner consumption T based on the dot count value C is changed. This makes it possible to bring the calculated toner consumption T closer to the actual toner consumption even if the actual toner consumption changes when forming an image based on the same image data before and after toner replenishment.

[0104] That is, according to this embodiment, it is possible to improve the accuracy of calculating the amount of toner consumption.

[0105] As described above, this embodiment uses a toner replenishment method (external replenishment method) in which toner is replenished from a toner pack 40 (replenishment container) located outside the image forming apparatus 100 to the developing container 8 (toner storage unit) inside the apparatus. In the toner replenishment method, it is important to accurately grasp the remaining toner amount Q in the developing container 8, reflect this in the display on the remaining amount display unit 400, and notify the user at an appropriate time to prompt them to replenish toner. If the calculation accuracy of the remaining toner amount Q is low, for example, if the user replenishes toner when a toner replenishment notification is issued even though the actual remaining toner amount Q is high, it is possible that not all of the toner in the toner pack 40 will be replenished to the developing container 8, resulting in some toner being wasted. Furthermore, if a toner replenishment notification is not issued even though the actual remaining toner amount Q is less than Qout, the toner in the developing container 8 may run out, resulting in poor image quality or damage to the developing roller 4.

[0106] Furthermore, this embodiment employs a cleanerless configuration in which the developing roller 4 collects residual toner that was not transferred to the recording material P (transfer receiving member) at the transfer unit N1 into the developer container 8. In a cleanerless configuration, a portion of the toner developed on the photosensitive drum 1 passes through the transfer unit N1, the charging unit N2, etc. and is collected into the developer container 8, where it is repeatedly used for image formation. This tends to increase the proportion of degraded toner with reduced charging performance. As a result, the mixing of fresh toner and degraded toner can easily increase the average charge amount of the toner on the developing roller 4, resulting in a change in the amount of toner consumed per image. Therefore, this technology, which changes the value of the coefficient k used to calculate the amount of toner consumed T before and after toner replenishment, can be particularly advantageous in a cleanerless configuration.

[0107] However, even in a configuration that includes a cleaning member that removes residual toner between the transfer unit N1 and the charging unit N2, toner deterioration itself occurs due to friction with the agitator 7 and the developing blade 6 in the developing container 8. Therefore, in an image forming apparatus that does not have a cleaner-less configuration, the value of the coefficient k may be changed when toner is replenished, as in this embodiment.

[0108] (Modification with a larger value of coefficient k) In Example 1, it was explained that when fresh toner and degraded toner are mixed due to toner replenishment, the average charge amount of the toner on the developing roller 4 becomes larger than before the toner replenishment, and the toner consumption per test image becomes smaller than before the toner replenishment. However, there may be cases where the average charge amount of the toner on the developing roller 4 becomes smaller due to toner replenishment than before the toner replenishment, and as a result, the toner consumption per test image becomes larger than before the toner replenishment.

[0109] For example, when the chargeability of the base resin of toner particles is very high, making it difficult to control the developability and transferability, additives that suppress the chargeability of the toner may be added. Specifically, additives with low electrical resistance can be used to dissipate charge from the base resin of toner particles, or slightly larger additives can be used to reduce the contact area between the toner and various components and suppress the charge amount. In this case, the toner immediately before toner replenishment has a higher chargeability than fresh toner because the additives have been embedded in the toner surface or migrated from the toner surface to other components due to repeated use in image formation. On the other hand, fresh toner supplied by toner replenishment has its chargeability suppressed by the additives and has high fluidity, so it tends to be preferentially carried by the developing roller 4. As a result, the average charge amount of the toner on the developing roller 4 immediately after toner replenishment is lower than that immediately before toner replenishment.

[0110] In such a case, when toner is replenished to the developing container 8, the control unit 90 changes the value of the coefficient k so that the value of the coefficient k after the toner replenishment is greater than the value of the coefficient k before the toner replenishment. In other words, the value of the coefficient k after the Nth toner replenishment and before the N+1th toner replenishment is changed to k n The value of the coefficient k after the N-1th toner supply and before the Nth toner supply is k n-1 In this case, in this modification, k n >k n-1 The value of the coefficient k is changed so that: By doing so, it is possible to improve the accuracy of calculating the amount of toner consumption in this modified example as well.

[0111] In this modified example, the interval between toner replenishment (P in FIG. 9(c)) when test images are repeatedly printed based on the same image data is n-1 , P n , P n+1 , …) is, ···>P n-1 >P n >P n+1 >P n+2 The relationship is as follows:

[0112] The value of coefficient k after toner replenishment compared to before toner replenishment can be appropriately adjusted by the designer of image forming apparatus 100 after understanding the characteristics of the toner and the apparatus.

[0113] (Modification regarding detection of toner replenishment) The attachment sensor 53 of this embodiment is merely one example of a detection means for detecting toner replenishment from the toner pack 40 (supply container). For example, when toner replenishment is complete, the user may operate the operation unit 300 to input the completion of toner replenishment, and the control unit 90 may detect toner replenishment based on the information from the operation unit 300. When toner replenishment is complete, the user may operate an external computer communicatively connected to the image forming apparatus 100 to input the completion of toner replenishment, so that the control unit 90 may detect toner replenishment. In this case, the operation unit 300 or a receiving unit (external interface) in the control unit 90 that receives a signal from the external computer is an example of a detection means for detecting toner replenishment. Alternatively, a tag (storage medium) may be attached to the toner pack 40, and when the toner pack 40 is attached to the attachment unit 57, the control unit 90 may read information from the tag to detect toner replenishment.

[0114] Example 2 In Example 2, we will explain how to change the charging voltage and / or developing voltage when toner is replenished. Below, elements with the same reference symbols as in Example 1 have basically the same configurations and functions as those explained in Example 1 unless otherwise explained, and we will mainly explain the parts that are different from Example 1.

[0115] One reason for changing the charging voltage and / or developing voltage when toner is replenished is to improve fog images. A fog image is an image defect in which a thin layer of toner adheres to the surface area (non-exposed area) on the photosensitive drum 1 where a toner image should not be developed, resulting in a thin image being formed in an area (white area) on the recording material P where an image should not be formed. The toner adhering to the non-exposed area of ​​the surface area on the photosensitive drum 1 that has passed through the developing unit 21 is called fog toner.

[0116] One of the causes of fog images is that the charging performance is reduced due to contamination of the charging roller 2, and the pre-exposure potential VD, which is the surface potential of the photosensitive drum 1 after the charging process, is reduced (its absolute value is smaller) than the designed value (-800 V in this embodiment). When the pre-exposure potential VD is reduced, a sufficient potential difference is not formed between the non-exposed area of ​​the photosensitive drum 1 and the developing roller 4 in the developing unit 21, and some of the toner on the developing roller 4 moves to the non-exposed area of ​​the photosensitive drum 1, resulting in fog toner.

[0117] One of the causes of contamination of the charging roller 2 is an increase in the number of toner particles that invade the charging section N2 (the nip between the charging roller 2 and the photosensitive drum 1) due to toner deterioration. That is, during repeated use in image formation, additives in the toner may become embedded in the toner surface due to rubbing by the developing blade 6 or the like, or the toner particles may become deformed, which may increase the adhesion of the toner to the photosensitive drum 1. When the adhesion of the toner to the photosensitive drum 1 increases, residual toner is more likely to be generated, and the amount of residual toner that reaches the charging section N2 increases. Furthermore, the increase in the adhesion of the toner to the photosensitive drum 1 itself is a factor that makes it easier for fogging toner to occur.

[0118] When there is little fog toner or transfer residual toner, even if toner adheres to the charging roller 2, it is charged to negative polarity by frictional charging caused by the sliding of the photosensitive drum 1 and the charging roller 2 at the charging section N2, and is gradually returned to the photosensitive drum 1. When there is an increase in fog toner or transfer residual toner, the pace at which toner adheres to the charging roller 2 increases, and depending on the above mechanism, the toner adhering to the charging roller 2 may not be sufficiently removed, causing gradual accumulation of dirt.

[0119] Therefore, when the proportion of undegraded fresh toner on the developing roller 4 increases due to toner replenishment, the occurrence of fog toner and transfer residual toner decreases, and the contamination of the charging roller 2 can be improved.

[0120] In this embodiment, we propose increasing the charging voltage when toner is replenished to further reduce fog toner and improve fog images. Increasing the charging voltage refers to increasing the absolute value of the DC component of the charging voltage. Increasing the charging voltage increases the surface potential (pre-exposure potential VD) of the photosensitive drum 1 after the charging process. As a result, in the developing unit 21, the potential difference Vback between the surface potential (pre-exposure potential VD) of the non-exposed area of ​​the photosensitive drum 1 and the potential (DC component of the developing voltage) of the developing roller 4 increases. The potential difference Vback is sometimes called the fog removal contrast because it prevents toner charged to the normal polarity from migrating from the developing roller 4 to the non-exposed area of ​​the photosensitive drum 1.

[0121] FIG. 11 shows an example of control of the charging voltage and developing voltage in this embodiment. The control unit 90 in this embodiment changes the charging voltage from −1400 V to −1500 V when toner is replenished. As a result, the pre-exposure potential VD of the portion of the photosensitive drum 1 that was not affected by the contamination of the charging roller 2 changes from −800 V to approximately −900 V. Even in the portion affected by the contamination of the charging roller 2, the pre-exposure potential VD becomes higher (increased in absolute value) than before the change in the charging voltage. Meanwhile, in the illustrated example, the developing voltage is constant at −400 V before and after toner replenishment. In this case, in the portion of the photosensitive drum 1 that was not affected by the contamination of the charging roller 2, the potential difference Vback before toner replenishment is −400 V, while the potential difference Vback after toner replenishment is −500 V. Furthermore, even in the portion of the photosensitive drum 1 that was affected by the contamination of the charging roller 2, the absolute value of the potential difference Vback after toner replenishment is greater than the potential difference Vback before toner replenishment. In this way, by increasing the absolute value of the potential difference Vback, it is possible to ensure a sufficient pre-exposure potential VD and potential difference Vback even if there are areas where the charging performance has decreased due to contamination of the charging roller 2, thereby further reducing the fog toner and improving the fog image.

[0122] 11 illustrates an example in which the charging voltage is increased when toner is replenished, but the developing voltage may also be decreased (its absolute value may be reduced) when toner is replenished. Also, the charging voltage may be increased and the developing voltage may be decreased. In either case, the potential difference Vback after toner replenishment is increased compared to before toner replenishment, providing the same advantages as in this embodiment.

[0123] In this way, the control unit 90 changes at least one of the charging voltage (first voltage) and the developing voltage (second voltage) when toner is replenished. In particular, the surface potential (pre-exposure potential VD) of the photosensitive drum 1 after charging by the charging roller 2 to which the charging voltage (first voltage) is applied is set to the first potential, and the potential of the developing roller 4 to which the developing voltage (second voltage) is applied is set to the developing potential (second potential). In this case, when toner is replenished, the control unit 90 of this embodiment changes at least one of the charging voltage (first voltage) and the developing voltage (second voltage) so that the potential difference Vback between the pre-exposure potential VD (first potential) and the developing potential (second potential) increases.

[0124] The charging voltage and / or developing voltage may be changed each time toner is replenished, or may be changed when toner is replenished a predetermined number of times since the installation of the image forming apparatus 100. The trigger for changing the charging voltage and / or developing voltage may be, for example, a detection signal from the attachment sensor 53, as in the first embodiment. The trigger may be an input operation indicating completion of toner replenishment on the operation unit 300 or an external computer, or reading of information from a tag on the toner pack 40.

[0125] In this embodiment, the potential difference Vback increases before and after toner replenishment. When the potential difference Vback increases, the amount of toner consumed decreases, especially at the edges of lines or text in an image and in halftone areas. The reason for this can be explained as follows.

[0126] In the development process, toner adheres to areas of the surface of the photosensitive drum 1 that are at a lower potential (closer to 0 V) ​​than the development potential (the DC component of the development voltage), developing a toner image. Meanwhile, the potential distribution of the latent image formed in the exposure process does not rise vertically from the pre-exposure potential VD to the post-exposure potential VL, but rises at a certain gradient. Therefore, as the potential difference Vback increases, the area that is at a lower potential than the development potential becomes narrower, and less toner adheres to the surface of the photosensitive drum 1. Because the above mechanism occurs at the edges of the latent image, it is more likely to occur in images with edges (images containing line drawings or text) than in solid images without edges, and is particularly noticeable in halftone areas with a high density of edges.

[0127] As described above, in this embodiment, the average charge amount of the toner carried on the developing roller 4 changes before and after toner replenishment, and in addition the potential difference Vback increases, so the toner consumption rate after toner replenishment is further reduced compared to embodiment 1. However, in this embodiment, by reducing the value of the coefficient k in consideration of the effect of the increase in potential difference Vback when toner is replenished, it is possible to appropriately respond to the change in the toner consumption rate.

[0128] Therefore, according to this embodiment, it is possible to improve the accuracy of calculating the toner consumption amount T based on the dot count value C. Also, just like in Figures 9(a) and 9(b) of the first embodiment, it is possible to maintain a correct relationship between the actual remaining toner amount and the displayed remaining toner amount.

[0129] When the image forming apparatus 100 of this embodiment is repeatedly printed with test images based on the same image data and toner is repeatedly replenished, it behaves as shown in Figure 12. In this example, when the Nth toner replenishment is performed, the charging voltage is changed to increase the potential difference Vback and the value of the coefficient k is decreased. When the N-1th and N+1th toner replenishment are performed, the charging voltage and the value of the coefficient k are not changed.

[0130] In this case, the actual toner consumption per test image after the Nth toner replenishment is less than before the Nth toner replenishment due to the influence of the change in the average charge amount of the toner and the widening of the potential difference Vback. Meanwhile, the value of the coefficient k after the Nth toner replenishment is changed to a smaller value than before the Nth toner replenishment. Therefore, after the Nth toner replenishment, the toner consumption per test image calculated based on the dot count value C decreases, and the slope of the graph becomes gentler. The number of prints from the Nth toner replenishment to the (N+1)th toner replenishment is defined as P n Then, P n-2 =P n-2 <P n =P n+1 It will look like this.

[0131] In this embodiment, an example has been described in which the charging voltage and / or developing voltage is changed when toner is replenished so that the potential difference Vback is wider than before toner replenishment. This is not limiting, and the charging voltage and / or developing voltage may be changed so that the potential difference Vback is narrower than before toner replenishment. In this case, the value of coefficient k after toner replenishment may be changed to a larger value than before toner replenishment. The potential difference Vback may be narrowed, for example, in the first embodiment, when toner replenishment increases the average charge amount of toner on the developing roller 4, resulting in an overall decrease in image density and the resulting thin or faint appearance of thin lines or small dots.

[0132] (Variation 1) Immediately after toner replenishment, the average charge amount of the toner on the developing roller 4 increases due to the mechanism described in the first embodiment, and the rate of toner consumption decreases. However, as the number of prints increases thereafter, the difference in properties between the toner replenished in the most recent toner replenishment and the old toner that was in the developing container 8 before the most recent toner replenishment is alleviated. As a result, the rate of toner consumption may return to the same level as before the most recent toner replenishment.

[0133] In this modified example, a configuration is proposed that can handle a situation in which the pace of toner consumption increases after the number of printed sheets has increased to a certain extent compared to immediately after toner replenishment.

[0134] 13(a) is a graph showing the change in the remaining toner amount Q in the developing container 8 in this modified example. When test images based on the same image data are repeatedly printed while toner is repeatedly replenished, the rate at which the remaining toner amount Q decreases immediately after the Nth toner replenishment is slower than before the toner replenishment. On the other hand, for the reasons described above, once the number of prints increases to a certain extent after the Nth toner replenishment, the rate at which the remaining toner amount Q decreases increases to about the same as before the Nth toner replenishment.

[0135] 13B is a graph showing the transition of the remaining amount of toner in the remaining amount display unit 400. In this modification, the value of the coefficient k (k n However, after a predetermined number of images have been output immediately after the Nth toner replenishment, the value of the coefficient k is returned to the same value as immediately before the Nth toner replenishment. Therefore, from immediately after the Nth toner replenishment until a predetermined number of images have been output, the slope D of the remaining toner amount calculated based on the dot count value C is n is the slope D just before the Nth toner supply n-1 On the other hand, after a predetermined number of images have been output, the slope D of the remaining toner amount calculated based on the dot count value C becomes gentler than n ″ is the slope D just before the Nth toner supply. n-1 It will be about the same.

[0136] In other words, the control unit 90 changes the value of the coefficient k after the current toner replenishment to the first value (k n-1 ) smaller than the second value (k n ), and before the next toner supply, the coefficient value is changed to the second value (k n ) and a third value (k n-1In this embodiment, if the third value is the same as the first value, that is, if the value of the coefficient k is changed to k n-1 From k n After changing to k n-1 However, the third value may be different from the first value.

[0137] By performing the above control, the remaining toner amount calculated based on the dot count value C becomes equal to or less than Qout (0%) at approximately the same timing as the number of prints Pd at which the actual remaining toner amount Q becomes equal to or less than Qout. Therefore, even if the pace of toner consumption increases after the number of prints has increased to a certain extent after toner replenishment, toner replenishment notification can be given at the appropriate time.

[0138] In the second embodiment, even if the potential difference Vback is increased for a while after toner replenishment and then returned to its original value after a period of time has passed in which the contamination of the charging roller 2 is eliminated, the rate of toner consumption may increase. Therefore, in the second embodiment, the charging voltage and / or the developing voltage may be changed when toner replenishment is performed, and then the charging voltage and / or the developing voltage may be returned to their original values. In other words, the control unit 90 may change at least one of the charging voltage (first voltage) and the developing voltage (second voltage) so as to increase the potential difference Vback after the current toner replenishment, and then change at least one of the charging voltage (first voltage) and the developing voltage (second voltage) so as to narrow the potential difference Vback before the next toner replenishment. This allows the toner replenishment notification to be issued at an appropriate time, even if the rate of toner consumption increases after a certain number of prints have been made since the toner replenishment, compared to immediately after the toner replenishment.

[0139] (Variation 2) In Example 1, when the charge amount of toner on the developing roller 4 increases due to toner replenishment, there may be cases where the toner consumption amount decreases for halftone images, while the toner consumption amount remains almost unchanged for text images and solid images. Also, in Example 2, when the potential difference Vback is increased after toner replenishment, there may be cases where the toner consumption amount decreases for halftone images, while the toner consumption amount remains almost unchanged for text images and solid images.

[0140] This is because, due to the characteristics of electrophotography, halftone images are more susceptible to the effects of toner charge than solid images, and are also more susceptible to changes in the potential difference Vback. The reason why the toner consumption of halftone images decreases when the potential difference Vback increases is as explained in Example 2.

[0141] The reason why the amount of toner consumed in a halftone image tends to decrease as the charge amount of toner on the developing roller 4 increases can be explained as follows using Figure 14(a). The horizontal axis of Figure 14(a) represents the average potential on the photosensitive drum 1, and the vertical axis represents the image density. The direction of the horizontal axis is such that the post-exposure potential VL is on the right and the pre-exposure potential VD is on the left. The average potential on the photosensitive drum 1 is the surface potential of the photosensitive drum 1 averaged over the surface area of ​​the photosensitive drum 1 such that the image density is constant. Vdc on the horizontal axis is the potential of the developing roller 4 (the DC component of the developing voltage).

[0142] In the surface region on the photosensitive drum 1 corresponding to the halftone image, regions of post-exposure potential VL and regions of pre-exposure potential VD are intermingled in small increments. Therefore, as shown in Figure 14(a), in the surface region on the photosensitive drum 1 corresponding to the halftone image, the average potential on the photosensitive drum 1 is an intermediate potential between the post-exposure potential VL and the pre-exposure potential VD. On the other hand, the region on the photosensitive drum 1 corresponding to the solid image (solid black region) is uniformly at the post-exposure potential VL, and the region on the photosensitive drum 1 corresponding to the white background (solid white region) is uniformly at the pre-exposure potential VD.

[0143] Increasing Vback causes fluctuations in the average potential on the photosensitive drum 1. In solid black areas, even if the average potential of the photosensitive drum 1 fluctuates slightly (fluctuation range ΔV), the fluctuation range ΔBk of the image density is small. On the other hand, in halftone areas, when the average potential of the photosensitive drum 1 fluctuates by the same fluctuation range ΔV, the fluctuation range ΔHT of the image density becomes large. One reason for this is that in solid black areas, toner is developed in multiple layers, whereas in halftone areas, toner is developed in a single layer and the coverage of the recording material is low, so a reduction in the amount of toner developed has a significant impact on the image density.

[0144] In any case, when the charge amount of the toner on the developing roller 4 is increased or the potential difference Vback is widened in Example 1 or Example 2, the amount of toner consumed may decrease in halftone images, while the amount of toner consumed may remain almost unchanged in text images or solid images.

[0145] To address this situation, this modified example changes the value of coefficient k used to calculate toner consumption based on the area occupied by the halftone region in the image formed in one image formation operation. In this embodiment, the value of coefficient k is changed so that the larger the area of ​​the halftone region, the smaller the value of coefficient k. The area of ​​the halftone region can be calculated, for example, by counting the pixels with a density range of 10% to 90% in a raster image obtained by image processing image data.

[0146] 14B shows an example of a decision flow for determining the value of the coefficient k in this modified example. Let S be the area of ​​the halftone region, and let S be a preset threshold value. A , S B , S C Let's say S A B C and S A corresponds to about 15% of the area of ​​the A4 size recording material P, and S B is about 30%, S C corresponds to about 50% of the area.

[0147] ​​The value of the coefficient k before the Nth toner supply is k n-1 The value of the coefficient k after the Nth toner supply is k n In this modification, the area S of the halftone region of the image to be printed is set to S A If it is less than (S11YES), k n k n-1 Set the area S equal to S A Bigger S B If it is less than (S12YES), k n k n-1 0.8 times (k n / k n-1 =0.8). The area S is set to S B Bigger S C If it is less than (S13YES), k n k n-1 0.65 times (k n / k n-1 =0.65). The area S is set to S c If it is equal to or greater than (S13NO), k n k n-1 0.5 times (k n / k n-1 =0.5).

[0148] The above-mentioned judgment flow may be performed for each image data to be formed. In other words, in continuous printing, the area S of the halftone region in the first image may differ from the area S of the halftone region in the second image. In this case, the value k of the coefficient k used to calculate the toner consumption amount for the first image may be n and the value k of the coefficient k used to calculate the toner consumption amount for the second image. n may be different.

[0149] An example of the remaining toner amount and the transition of the toner remaining amount display in this modified example is shown in FIGS. 15(a) to 15(d).

[0150] FIG. 15(a) shows the change in the remaining toner amount when an image (S13NO) with a large area S of halftone regions, such as a full halftone image, is continuously printed. When the Nth toner replenishment is performed, the charge amount of the toner on the developing roller 4 increases, and as a result, the pace of toner consumption slows compared to before the toner replenishment. FIG. 15(b) shows the change in the remaining toner amount display on the remaining toner amount display unit 400 under the same circumstances as FIG. 15(a). In FIGS. 15(a) and 15(b), an image with a large area S of halftone regions is printed, so the value k of the coefficient k is n is k n-1 As a result, the value of the coefficient k after toner replenishment is set to k n The rate of decrease (slope DDn) of the remaining toner amount calculated using the coefficient k before toner replenishment is k n-1 The rate of decrease (slope DD) of the remaining toner amount calculated using

[0151] By performing the above control, the remaining toner amount calculated based on the dot count value C becomes equal to or less than Qout (0%) at approximately the same timing as the number of prints Pe at which the actual remaining toner amount Q becomes equal to or less than Qout. Therefore, even when printing an image that includes many halftone images that are easily affected by the charge amount of toner, toner replenishment notification can be performed at an appropriate timing.

[0152] FIG. 15(c) shows the change in the remaining toner amount when an image containing only text and no halftone areas is continuously printed. After the Nth toner replenishment, the charge amount of the toner on the developing roller 4 increases, but the toner consumption rate remains almost unchanged from before the toner replenishment. FIG. 15(d) shows the change in the remaining toner amount display on the remaining toner amount display unit 400 under the same circumstances as FIG. 15(c). In FIGS. 15(c) and 15(d), an image containing no halftone areas (S=0) is printed, so the value k of the coefficient k is n is k n-1 As a result, the value of the coefficient k after toner replenishment is set to k n The rate of decrease (slope DA) of the remaining toner amount calculated using the coefficient k before toner replenishment is k n-1The rate of decrease (slope DA) of the remaining toner amount calculated using

[0153] By performing the above control, the remaining toner amount calculated based on the dot count value C becomes equal to or less than Qout (0%) at approximately the same timing as the number of prints Pf at which the actual remaining toner amount Q becomes equal to or less than Qout. Therefore, even when printing an image that is less affected by the amount of charge on the toner (an image that does not include a halftone image), toner replenishment notification can be given at an appropriate timing.

[0154] In the above-described embodiments and modifications, there are cases where the rate of change in the toner remaining amount display per print before toner replenishment differs from the rate of change in the toner remaining amount display per print after toner replenishment (e.g., Example 1 in FIG. 9B). To determine the rate of change in the toner remaining amount display (the slope Dn of the graph), for example, monitor the remaining amount display panel 401 in FIG. 7 or the gauge G1 or value G2 in FIG. 8. When determining the rate of change in the toner remaining amount display, it is not necessary to continue printing images from 100% to 0% toner remaining. It is advisable to check whether the change in the toner remaining amount display after printing, for example, approximately 100 images, differs before and after toner replenishment. It is also advisable to check whether the number of prints required for the display on the remaining amount display panel 401 in FIG. 7 to change by one level differs before and after toner replenishment.

[0155] In the above explanation, it has been assumed that the toner present in the developer container 8 before toner replenishment (toner in the container) and the toner replenished into the developer container 8 by toner replenishment (replenishment toner) are the same toner in their new state. However, this is not limited to this, and the present technology can also be applied to cases where the toner in the container and the replenishment toner are different toners. "Different toners" means that at least one of the toner characteristics (e.g., particle size, viscoelasticity, shape, hardness, fluidity, charging performance, material, etc.), additives (material, size, number of parts added, addition strength), or manufacturing method (suspension polymerization method, pulverization method, solution suspension method, emulsion aggregation method), etc. are different.

[0156] If the type of toner in the container and the type of replenished toner are different, a defective image may occur due to the mixture of multiple types of toner in the developer container 8. In such a case, there is a method of replenishing new toner to recover from the defective image. The user may attempt to recover by replenishing new toner, or a service technician may replenishing new toner. Furthermore, as in Example 2, an attempt may be made to recover by changing the latent image settings (settings of charging voltage and developing voltage).

[0157] To summarize the cases described so far, there are cases where the toner in the container and the replenished toner are the same, cases where the toner in the container and the replenished toner are of different types, cases where the toner in the container is a mixture of multiple types of toner and the toner being replenished is one type of toner or a toner different from any of the multiple types.Furthermore, there are cases where the user or service person only replenishes toner, and cases where the latent image setting is changed after toner replenishment by replenishment operation detection, memory tag, or manual setting by the user or service person.

[0158] In any of the above cases, the present technology can be applied and provides the same advantages as the above-described embodiment: When toner is replenished, the accuracy of calculating the amount of toner consumption can be improved by changing the value of the coefficient k used to calculate the amount of toner consumption based on the dot count value.

[0159] In the above embodiment, the coefficient k is changed in accordance with the change in toner consumption after toner replenishment. However, it is also possible to change the image formation conditions so that the toner consumption does not change before and after toner replenishment. Examples of changing the image formation conditions include correcting the γ curve (tone curve), adjusting the line width / dot size, and changing the latent image settings. Correcting the γ curve refers to correcting the relationship between the half-tone density of the input data and the half-tone density of the output data in image processing to create data for driving the exposure device 10 from externally input image data. Adjusting the line width / dot size refers to changing the line width of the fine line pattern that constitutes the halftone or the size of each point in the dot pattern. Changing the latent image settings refers to changing the difference (Vback) from the pre-exposure potential VD, the difference (Vcont) between the development potential and the post-exposure potential VL, or the development potential by adjusting the charging voltage, development voltage, laser light intensity, etc.

[0160] Although changing the image forming conditions can suppress changes in image density and toner consumption for the same image data before and after toner replenishment, it may be difficult to adjust the image density and toner consumption so that they do not change at all. According to this technology, even in cases where changing the image forming conditions is difficult, it is possible to improve the accuracy of calculating toner consumption and remaining toner, and at least provide the user with accurate information on remaining toner and notify them of toner replenishment at an appropriate time. Note that this technology may be used in combination with a technology for changing the image forming conditions to suppress changes in image density before and after toner replenishment.

[0161] In the above embodiment, a monochrome printer has been described as an example, but the present technology can also be applied to a color printer that forms color images using toner of multiple colors. In the case of a color printer, the toner consumption amount and the remaining toner amount are calculated for each of the multiple color toners.

[0162] In the above embodiment, a direct transfer type image forming apparatus in which a toner image formed on the photosensitive drum 1 (photosensitive member) is directly transferred onto a recording material P as a transfer recipient has been described, but the present technology can also be applied to an intermediate transfer type image forming apparatus. In the intermediate transfer type, the toner image formed on the photosensitive drum 1 (photosensitive member) is primarily transferred onto an intermediate transfer member as a transfer recipient, and then the toner image is secondarily transferred from the intermediate transfer member onto the recording material P.

[0163] In the above embodiment, a configuration has been exemplified in which toner is replenished with the toner pack 40 (supply container) attached to the attachment portion 57. However, the present technology is not limited to this, and may be applied to an image forming apparatus configured such that replenishment toner is poured from a supply container that is not attached to the apparatus main body through a supply port exposed to the outside of the apparatus main body, for example.

[0164] (Other embodiments) The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program.The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0165] Summary of the Disclosure The present disclosure includes at least the following configurations or methods. (Configuration 1) A photoreceptor; a toner storage unit that stores toner; a developing member that carries the toner contained in the toner container and supplies it to the photosensitive member, thereby developing the latent image on the photosensitive member into a toner image; a mounting portion to which a supply container containing toner can be attached, the mounting portion allowing toner to be replenished from the supply container to the toner storage portion in a state where at least a portion of the supply container is located outside the image forming apparatus; a control unit that calculates the amount of toner consumption by multiplying a count value that correlates with the number of pixels that constitute the toner image by a coefficient; Equipped with the control unit changes the value of the coefficient when the toner is replenished. An image forming apparatus characterized by: (Configuration 2) the control unit sets the value of the coefficient after the toner replenishment to a value smaller than the value of the coefficient before the toner replenishment. 2. The image forming apparatus according to claim 1, (Configuration 3) an average charge amount of the toner carried on the developing member after the toner replenishment is greater in absolute value than an average charge amount of the toner carried on the developing member before the toner replenishment is performed; 3. The image forming apparatus according to configuration 2. (Configuration 4) the control unit decreases the value of the coefficient every time the toner is replenished. 4. The image forming apparatus according to configuration 2 or 3. (Configuration 5) when the control unit repeatedly executes image forming operations based on the same image data, the control unit changes the value of the coefficient when the toner is replenished so that a calculation result of the amount of toner consumed in the image forming operations after the toner is replenished is smaller than a calculation result of the amount of toner consumed in the image forming operations after the toner is replenished. 5. The image forming apparatus according to any one of configurations 1 to 4. (Configuration 6) the control unit changes the value of the coefficient to a second value smaller than the first value, which is the value of the coefficient before the current toner replenishment, after the current toner replenishment is performed, and then changes the value of the coefficient to a third value larger than the second value before the next toner replenishment is performed. 4. The image forming apparatus according to any one of configurations 1 to 3. (Configuration 7) the control unit sets the value of the coefficient after the toner replenishment to a value greater than the value of the coefficient before the toner replenishment. 2. The image forming apparatus according to claim 1, (Configuration 8) A charging member; a first voltage applying section that applies a first voltage to the charging member to charge the surface of the photosensitive member; a second voltage applying section that applies a second voltage to the developing member to develop the latent image; Further provided with the control unit changes at least one of the first voltage and the second voltage when the toner is replenished. 8. The image forming apparatus according to any one of configurations 1 to 7. (Configuration 9) a surface potential of the photosensitive member after being charged by the charging member to which the first voltage has been applied is defined as a first potential, and a potential of the developing member to which the second voltage has been applied is defined as a second potential; the control unit changes at least one of the first voltage and the second voltage so that a potential difference between the first potential and the second potential increases when the toner is replenished. 9. The image forming apparatus according to configuration 8, (Configuration 10) the control unit changes at least one of the first voltage and the second voltage so that the potential difference increases after the current toner supply is performed, and then changes at least one of the first voltage and the second voltage so that the potential difference decreases before the next toner supply is performed. 10. The image forming apparatus according to configuration 9, (Configuration 11) the control unit changes the value of the coefficient used to calculate the amount of toner consumed by the image forming operation according to the size of a halftone region of the image formed by the image forming operation after the toner replenishment. 11. The image forming apparatus according to any one of configurations 1 to 10. (Configuration 12) The image forming apparatus further includes a transfer unit that transfers the toner image from the photosensitive member to a transfer-receiving member in a transfer unit, the toner that has not been transferred to the transfer object in the transfer unit is collected in the toner storage unit by the developing member; 12. The image forming apparatus according to any one of configurations 1 to 11. (Configuration 13) the control unit calculates the amount of toner remaining in the toner storage unit based on the calculated amount of toner consumed, and when the amount of toner remaining becomes equal to or less than a predetermined threshold, issues a notification to a user urging them to replenish the toner. 13. The image forming apparatus according to any one of configurations 1 to 12. (Configuration 14) the control unit causes a display unit to display remaining amount information regarding the remaining amount of toner in the toner storage unit based on the count value and the toner consumption amount calculated using the coefficient. 13. The image forming apparatus according to any one of configurations 1 to 12. (Configuration 15) the display unit is an operation panel included in the image forming apparatus, the remaining amount information is displayed on a screen of the operation panel. 15. The image forming apparatus according to configuration 14. (Configuration 16) the display unit has a plurality of lamps provided on an outer surface of the image forming apparatus, The remaining amount information is displayed by whether or not the plurality of lamps are lit, or by the manner in which they are lit. 15. The image forming apparatus according to configuration 14. (Configuration 17) further comprising a detection means for detecting attachment / detachment of the supply container to / from the attachment portion, the control unit changes the value of the coefficient based on the detection by the detection means of the attachment or detachment of the refill container. 17. The image forming apparatus according to any one of configurations 1 to 16. (Configuration 18) further comprising an operation unit that accepts operations from a user; the control unit changes the value of the coefficient based on an input to the operation unit indicating completion of the toner replenishment using the replenishment container. 17. The image forming apparatus according to any one of configurations 1 to 16. (Configuration 19) further comprising an exposure device that exposes the photosensitive member; the control unit develops the image data into a raster image, and drives the exposure device based on the raster image to form the latent image on the photosensitive member; The count value is the number of dots that constitute the raster image. 19. The image forming apparatus according to any one of configurations 1 to 18. (Configuration 20) an exposure device having a light source and exposing the photosensitive member to light emitted by the light source; The count value is the cumulative light emission time of the light source. 19. The image forming apparatus according to any one of configurations 1 to 18. [Explanation of symbols]

[0166] 1... photosensitive member (photosensitive drum) / 4... developing member (developing roller) / 8... toner storage section (developing container) / 40... supply container (toner pack) / 57... mounting section / 90... control section

Claims

1. A photoreceptor; a toner storage unit that stores toner; a developing member that carries the toner contained in the toner container and supplies it to the photosensitive member, thereby developing the latent image on the photosensitive member into a toner image; a mounting portion to which a supply container containing toner can be attached, the mounting portion allowing toner to be replenished from the supply container to the toner storage portion in a state where at least a portion of the supply container is located outside the image forming apparatus; a control unit that calculates the amount of toner consumption by multiplying a count value that correlates with the number of pixels that constitute the toner image by a coefficient; Equipped with the control unit changes the value of the coefficient when the toner is replenished. An image forming apparatus characterized by:

2. the control unit sets the value of the coefficient after the toner replenishment to a value smaller than the value of the coefficient before the toner replenishment.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

3. an average charge amount of the toner carried on the developing member after the toner replenishment is greater in absolute value than an average charge amount of the toner carried on the developing member before the toner replenishment is performed; 3. The image forming apparatus according to claim 2, wherein the image forming apparatus is a recording medium.

4. the control unit decreases the value of the coefficient every time the toner is replenished.

3. The image forming apparatus according to claim 2, wherein the image forming apparatus is a recording medium.

5. when the control unit repeatedly executes image forming operations based on the same image data, the control unit changes the value of the coefficient when the toner is replenished so that a calculation result of the amount of toner consumed in the image forming operations after the toner is replenished is smaller than a calculation result of the amount of toner consumed in the image forming operations after the toner is replenished.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

6. the control unit changes the value of the coefficient to a second value smaller than the first value, which is the value of the coefficient before the current toner replenishment, after the current toner replenishment is performed, and then changes the value of the coefficient to a third value larger than the second value before the next toner replenishment is performed.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

7. the control unit sets the value of the coefficient after the toner replenishment to a value greater than the value of the coefficient before the toner replenishment.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

8. A charging member; a first voltage applying section that applies a first voltage to the charging member to charge the surface of the photosensitive member; a second voltage applying section that applies a second voltage to the developing member to develop the latent image; Further provided with the control unit changes at least one of the first voltage and the second voltage when the toner is replenished.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

9. a surface potential of the photosensitive member after being charged by the charging member to which the first voltage has been applied is defined as a first potential, and a potential of the developing member to which the second voltage has been applied is defined as a second potential; the control unit changes at least one of the first voltage and the second voltage so that a potential difference between the first potential and the second potential increases when the toner is replenished.

9. The image forming apparatus according to claim 8,

10. the control unit changes at least one of the first voltage and the second voltage so that the potential difference increases after the current toner supply is performed, and then changes at least one of the first voltage and the second voltage so that the potential difference decreases before the next toner supply is performed.

10. The image forming apparatus according to claim 9,

11. the control unit changes the value of the coefficient used to calculate the amount of toner consumed by the image forming operation according to the size of a halftone region of the image formed by the image forming operation after the toner replenishment.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

12. The image forming apparatus further includes a transfer unit that transfers the toner image from the photosensitive member to a transfer-receiving member in a transfer unit, the toner that has not been transferred to the transfer object in the transfer unit is collected in the toner storage unit by the developing member; 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

13. the control unit calculates the amount of toner remaining in the toner storage unit based on the calculated amount of toner consumed, and when the amount of toner remaining becomes equal to or less than a predetermined threshold, issues a notification to a user urging them to replenish the toner.

13. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

14. the control unit causes a display unit to display remaining amount information regarding the remaining amount of toner in the toner storage unit based on the count value and the toner consumption amount calculated using the coefficient.

13. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

15. the display unit is an operation panel included in the image forming apparatus, the remaining amount information is displayed on a screen of the operation panel.

15. The image forming apparatus according to claim 14.

16. the display unit has a plurality of lamps provided on an outer surface of the image forming apparatus, The remaining amount information is displayed by whether or not the plurality of lamps are lit, or by the manner in which they are lit.

15. The image forming apparatus according to claim 14.

17. further comprising a detection means for detecting attachment / detachment of the supply container to / from the attachment portion, the control unit changes the value of the coefficient based on the detection by the detection means of the attachment or detachment of the refill container.

13. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

18. further comprising an operation unit that accepts operations from a user; the control unit changes the value of the coefficient based on an input to the operation unit indicating completion of the toner replenishment using the replenishment container.

13. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

19. further comprising an exposure device that exposes the photosensitive member; the control unit develops the image data into a raster image, and drives the exposure device based on the raster image to form the latent image on the photosensitive member; The count value is the number of dots that constitute the raster image.

13. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

20. an exposure device having a light source and exposing the photosensitive member to light emitted by the light source; The count value is the cumulative light emission time of the light source.

13. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

Images