Image forming apparatus

Abstract

An image forming apparatus is disclosed. An image forming apparatus includes: a photosensitive member; a toner storage portion; a developing member configured to develop the latent image on the photosensitive member into a toner image; an attachment portion to which a replenishment container containing toner is attached, the attachment portion configured to allow toner replenishment from the replenishment container into the toner storage portion; and a control unit configured to calculate a toner consumption amount by multiplying a count value related to a number of pixels constituting the toner image by a coefficient, the control unit configured to change a value of the coefficient in a case where toner replenishment is performed.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus for forming an image on a recording material. Background Art

[0002] The following replenishment type (toner replenishment type or external replenishment type) is known: toner is replenished from outside the image forming apparatus to a toner storage portion storing toner as a developer using a replenishment container inside the image forming apparatus. Japanese Patent Application Publication No. 2020-86450 discloses an image forming apparatus including a developer storage chamber and an attachment port through which a developer supply bottle is attached or detached. The image forming apparatus is configured so that when the developer supply bottle is attached to the attachment port, the developer in the developer supply bottle moves into the developer storage chamber by its own weight.

[0003] As a method for the control unit of an image forming apparatus to grasp the remaining amount of toner in the toner storage portion, there is a dot counting method (also referred to as a pixel counting method) that calculates the toner consumption amount based on the number of pixels forming a toner image. However, when toner is replenished, the toner consumption amount calculated by the dot counting method may deviate from the actual consumption amount. Summary of the Invention

[0004] This embodiment provides an image forming apparatus that can improve the accuracy of calculating toner consumption.

[0005] According to one aspect of the present invention, an image forming device includes: a photosensitive member; a colorant storage portion configured to store colorant; a developing member configured to carry the colorant stored in the colorant storage portion, supply the colorant to the photosensitive member, and develop the latent image on the photosensitive member into a colorant image; an attachment portion to which a replenishing container containing the colorant is attached, the attachment portion being configured to allow replenishment of the colorant from the replenishing container to the colorant storage portion in a state where at least a portion of the replenishing container is outside the image forming device; and a control unit configured to calculate a toner consumption by multiplying a count value related to the number of pixels constituting the colorant image by a coefficient, the control unit being configured to change the value of the coefficient when the toner replenishment is performed.

[0006] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1A is a schematic diagram of the image forming apparatus according to the first embodiment.

[0008] Figure 1B is a schematic diagram of the image forming apparatus with a toner pack attached according to the first embodiment.

[0009] Figure 2A 1 and 2 are views for explaining a developing container and a toner package according to the first embodiment.

[0010] Figure 2B 1 and 2 are views for explaining a developing container and a toner package according to the first embodiment.

[0011] Figure 3A 1 and 2 are views for explaining a developing container and a toner package according to the first embodiment.

[0012] Figure 3B 1 and 2 are views for explaining a developing container and a toner package according to the first embodiment.

[0013] Figure 4 1 and 2 are views for explaining a toner package according to the first embodiment.

[0014] Figure 5A 1 and 2 are views for explaining a toner package according to the first embodiment.

[0015] Figure 5B It is a diagram for explaining a toner pack according to a modified example.

[0016] Figure 5C It is a diagram for explaining a toner pack according to a modified example.

[0017] Figure 6 is a block diagram illustrating a control configuration of the image forming apparatus according to the first embodiment.

[0018] Figure 7A 1 and 2 are views for explaining the remaining amount display panel according to the first embodiment.

[0019] Figure 7B 1 and 2 are views for explaining the remaining amount display panel according to the first embodiment.

[0020] Figure 7C 1 and 2 are views for explaining the remaining amount display panel according to the first embodiment.

[0021] Figure 8 is an example of a display screen on the remaining amount display unit according to the first embodiment.

[0022] Figure 9A is a graph showing an example of transition of the remaining toner amount in the first embodiment.

[0023] Figure 9B is a graph showing an example of transition of the remaining toner amount indication in the first embodiment.

[0024] Figure 9C is a graph showing an example of transition of the remaining toner amount indication in the first embodiment.

[0025] Figure 10 is a flowchart illustrating a control method according to the first embodiment.

[0026] Figure 11 is a diagram illustrating an example of controlling the charging voltage and the developing voltage according to the second embodiment.

[0027] Figure 12 is a graph showing an example of transition of the remaining toner amount indication in the second embodiment.

[0028] Figure 13A is a graph showing an example of transition of the remaining toner amount in the first modification.

[0029] Figure 13B is a graph showing an example of transition of the remaining toner amount indication in the first modification.

[0030] Figure 14A 1 and 2 are diagrams for explaining density fluctuation of a halftone image in the second modification.

[0031] Figure 14B is a diagram illustrating a flow for determining the coefficient k in the second modification.

[0032] Figure 15A is a graph showing an example of transition of the remaining toner amount in the second modification.

[0033] Figure 15B is a graph showing an example of transition of the remaining toner amount indication in the second modification.

[0034] Figure 15C is a graph showing an example of transition of the remaining toner amount in the second modification.

[0035] Figure 15D is a graph showing an example of transition of the remaining toner amount indication in the second modification. DETAILED DESCRIPTION

[0036] Hereinafter, embodiments according to the present disclosure will be described with reference to the accompanying drawings.

[0037] First embodiment

[0038] A first embodiment of the present disclosure will be described. Figure 1Ais a schematic diagram illustrating an image forming apparatus 100 according to a 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. As the recording material P (recording medium), various sheet materials of different sizes and materials such as paper (such as plain paper and thick paper), sheet materials subjected to surface treatment such as coated paper, sheets with special shapes such as envelopes and index paper, plastic films, and cloth can be used. The maximum size of the recording material P on which an image can be formed by the image forming apparatus 100 of this embodiment is a letter size (215.9 mm) having a certain length in the width direction orthogonal to the recording material conveying direction.

[0039] like Figure 1A , the image forming apparatus 100 includes an apparatus body M, a process unit 9, an exposure unit 10, a transfer roller 13, a fixing unit 14, and a control unit 90. The apparatus body M has a housing including a frame member forming a frame of the apparatus body M and a cover member forming an outer surface of the apparatus body M. The process unit 9, the exposure unit 10, the transfer roller 13, the fixing unit 14, and the control unit 90 are attached to the apparatus body M.

[0040] The process unit 9 may be fixed to the device body M under the assumption that, for example, the process unit 9 is not attached or detached by a user. The process unit 9 may be a unit (cartridge) attachable to or detachable from the device body M by a user.

[0041] Process unit 9 is a direct transfer electrophotographic unit. It includes a photosensitive drum 1 and at least one processing unit that acts on the photosensitive drum 1. A processing unit is a unit or component that performs at least one of the steps of charging, exposure, development, transfer, neutralization, and cleaning in electrophotography. In this embodiment, process unit 9 includes the photosensitive drum 1, a charging roller 2 serving as a charging unit, a developing unit 20 serving as a developing unit, a neutralizing unit 11 serving as a neutralizing unit, and a brush member 12.

[0042] The photosensitive drum 1 is a photosensitive member (image bearing member) that carries a latent image and a toner image. The photosensitive drum 1 is a photosensitive member that is rotatable around a rotation axis CP and is formed into a cylindrical shape (drum shape). The photosensitive drum 1 of this embodiment has a photosensitive layer formed of a negatively charged organic photosensitive member on a drum-shaped substrate formed of aluminum. More specifically, the photosensitive drum 1 is a rigid member formed by sequentially applying a resistance layer, a primer layer, and a photosensitive layer on the peripheral surface of an aluminum cylinder having a diameter of 24 mm by a dip coating method. The photosensitive layer includes a charge generating layer and a charge transporting layer. The charge transporting layer has a film thickness of 22 μm. When the image is formed, the photosensitive drum 1 is driven by a motor M1 ( Figure 6) is driven to rotate about a rotation axis CP at a predetermined peripheral speed in a direction indicated by an arrow L. The peripheral speed of the photosensitive drum 1 defines the speed at which the image forming apparatus 100 forms an image, and is therefore referred to as a process speed.

[0043] The charging roller 2 serving as a charging member contacts the photosensitive drum 1 with a predetermined pressure contact force to form a charging portion N2. Figure 6 ) applies a charging voltage to uniformly charge 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 having the same polarity as the normal polarity of the toner (in this embodiment, negative polarity). For example, a DC voltage of -1400 V is applied to the charging roller 2 of this embodiment as the charging voltage, and the surface 1a of the photosensitive drum 1 is charged until the surface potential of the photosensitive drum 1 (pre-exposure potential VD) reaches -800 V.

[0044] As an example, the charging roller 2 includes a core metal having a diameter of 6 mm, a base layer of polyepichlorohydrin rubber, and a surface layer of urethane, and is formed to have an outer diameter of 12 mm. The charging roller 2 has, for example, a 1×10 6 The charging roller 2 has a resistance of Ω or less. The charging roller 2 has a hardness of, for example, 70 degrees as a measured value obtained by an MD-1 rubber hardness meter. Note that the charging voltage in this embodiment is a direct current (DC) voltage, but may be, for example, a voltage obtained by superimposing an alternating current (AC) voltage on a DC voltage.

[0045] The exposure unit 10 is an exposure portion that exposes the photosensitive drum 1. The exposure unit 10 of the present embodiment is a laser scanner unit. That is, the exposure unit 10 includes a light source 10a that emits laser light and a scanning optical system (polygonal mirror, fθ lens, etc.) that guides the laser light emitted 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 and emits, for example, a laser light with a wavelength of 800nm. In addition, the light source 10a can change the amount of laser light to be output. Note that the exposure unit 10 is not limited to a laser scanner unit, and for example, an LED exposure unit having an LED array as a light source can be used, in which a plurality of LEDs are arranged along the rotation axis direction of the photosensitive drum 1.

[0046] The developing unit 20 includes a developing container 8, a developing roller 4, and a supply roller 5. The developing container 8 constitutes the frame of the developing unit 20. The developing container 8 is an example of a toner storage unit that stores toner as a developer. A storage chamber 8a and a developing chamber 8b are formed inside the developing container 8 as spaces for accommodating toner. The storage chamber 8a and the developing chamber 8b are connected to each other to allow the toner to move between them.

[0047] The developing roller 4 and the supply roller 5 are rotatably supported by the developing container 8. The developing roller 4 is a developing member (developer carrying member) that carries toner, supplies toner to the photosensitive drum 1, and develops the latent image on the photosensitive drum 1 into a toner image. The developing roller 4 is disposed in the opening of the developing 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 is adjacent to the developing roller 4 and removes toner that remains on the developing roller 4 and has not been transferred to the photosensitive drum 1 by the developing section 21. The supply roller 5 supplies the toner stored in the developing container 8 to the surface of the developing roller 4. The rotation direction of the supply roller 5 can be such that the movement direction of the surface of the developing roller 4 and the movement direction of the surface of the supply roller 5 are opposite in the portion facing the developing roller 4 (reverse direction), or the supply roller 5 and the developing roller 4 can rotate together (co-rotating direction). The supply roller 5 of this embodiment rotates in the reverse direction relative to the developing roller 4.

[0048] The developing unit 20 of this embodiment uses a contact developing method as a developing method. That is, the toner layer carried on the developing roller 4 contacts the photosensitive drum 1 in the developing portion 21. Figure 6 ) applies a development voltage to the developing roller 4. For example, the development voltage is a DC voltage having the same polarity as the normal polarity of the toner. Under the development 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 according to the potential distribution of the surface 1a, thereby developing the electrostatic latent image into a toner image.

[0049] In this embodiment, a reversal development system is employed. That is, a toner image is developed by toner adhering to the surface area of ​​the photosensitive drum 1 (exposed area / image area) whose charge amount decays when the surface area of ​​the photosensitive drum 1 is exposed in the exposure step after being charged in the charging step. On the other hand, no toner adheres to the surface area of ​​the photosensitive drum 1 that was not exposed in the exposure step (non-exposed area / non-image area), and no toner image is developed.

[0050] As an example, the developing roller 4 includes a core metal having a diameter of 6 mm, a base layer formed of silicone rubber on the outer peripheral side 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 to 1×10 12 Ω. As an example, the supply roller 5 is a rubber roller having electrical conductivity and elasticity and including a core metal having 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 to 1×10 8The hardness of the supply roller 5 can be measured by measuring the load when a flat plate having a width of 50 mm in the rotation axis direction of the supply roller 5 is inserted 1 mm from the surface of the supply roller 5 toward the rotation axis, and is 200 gf in this embodiment.

[0051] A stirring member 7 is disposed inside the developing container 8. The stirring member 7 is driven to rotate by the motor M1 to stir the toner in the developing container 8. The stirring member 7 feeds the toner toward the developing roller 4 and the supply roller 5. In addition, the stirring member 7 has a function of circulating the toner that is not used for development but is peeled off from the developing roller 4 in the developing container 8 to make the toner in the developing container 8 uniform.

[0052] A developing blade 6 that limits the amount of toner carried on the developing roller 4 is disposed at an opening portion of the developing container 8 where the developing roller 4 is disposed. The toner supplied to the surface of the developing roller 4 is uniformly thinned as it passes through a portion where the developing roller 4 and the developing blade 6 face each other while the developing roller 4 is rotating, and is charged to a normal polarity (negative polarity) by friction charging.

[0053] As an example, the developing scraper 6 is a metal plate (for example, a stainless steel plate) having a thickness of 0.1 mm, and its base portion (fixed end) is supported by a support portion provided in the developing container 8. The developing scraper 6 is arranged in a posture inclined upstream in the direction of rotation of the developing roller 4 from the base (fixed end) toward the top end (free end), so that the top end is adjacent to the surface of the developing roller 4. The developing scraper 6 used in this embodiment is a sheet metal member processed by cutting the top end of a stainless steel plate (using a stainless steel: SUS metal sheet) from the side whose surface is adjacent to the developing roller 4. By the cutting process, the top end portion of the developing scraper 6 is bent in the cutting direction.

[0054] The transfer roller 13 serving as a transfer unit is adjacent to the photosensitive drum 1 to form a transfer portion N1 between the transfer roller 13 and the photosensitive drum 1. As an example, the transfer roller 13 includes a core metal having a diameter of 6 mm and a base layer of ion-conductive sponge formed on the outer peripheral side of the core metal with an outer diameter of 15 mm. The resistance value of the transfer roller 13 in an environment with a temperature of 22°C is, for example, 4×10 7 Ω, and the hardness as a measurement value obtained by an Asker C rubber durometer manufactured by Kobunshi Keiki Co., Ltd. is 30 degrees. The width of the outer peripheral surface of the transfer roller 13 in the rotation axis direction of the photosensitive drum 1 is substantially equal to the letter size (8.5 inches = 215.9 mm).

[0055] A neutralization unit 11 that neutralizes the surface 1a of the photosensitive drum 1 is provided downstream of the transfer portion N1 and upstream of the charging portion N2 in the rotational direction (direction indicated by arrow L) of the photosensitive drum 1. More specifically, the neutralization unit 11 is disposed between the brush member 12 and the charging roller 2 in the rotational direction of the photosensitive drum 1. The neutralization unit 11 neutralizes the surface potential of the photosensitive drum 1 before reaching the charging portion N2, so as to generate stable discharge in the charging portion N2.

[0056] The brush member 12 is supported by a support member (not shown) and its position is fixed. As the photosensitive drum 1 rotates, the brush member 12 rubs against the surface of the photosensitive drum 1. The brush member 12 collects paper dust transferred from the recording material P to 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 downstream of the brush member 12 in the rotational direction of the photosensitive drum 1.

[0057] The fixing unit 14 is a thermal fixing type that performs an image fixing process by heating and melting the colorant on the recording material P. The fixing unit 14 of the present embodiment includes a fixing film 14a serving as a heating member (fixing member), a heater serving as a heat source for heating the heating member, and a pressure roller 14b adjacent to the fixing film 14a. The fixing film 14a is a tubular film having flexibility. The heater is, for example, a ceramic heater having a pattern of a heating resistor printed on a ceramic substrate, and is disposed in the internal space of the fixing film 14a. The pressure roller 14b is disposed in such a manner that the fixing film 14a is sandwiched between the pressure roller 14b and the heater. A clamping portion (fixing clamping portion) is formed between the fixing film 14a and the pressure roller 14b.

[0058] As the heating member, for example, a cylindrical fixing roller or an endless fixing belt stretched around a plurality of rollers can be used. As the heat source, a halogen heater that generates radiant heat or a coil unit that generates heat from a conductive layer in the heating member by electromagnetic induction can be used.

[0059] Image forming operation

[0060] A series of operations (image forming operation and printing operation) in which the image forming apparatus 100 forms an image on a recording material P using toner while conveying the recording material P will be described. When an image forming command is output to the image forming apparatus 100, the image forming operation is started based on image data input from an external device connected to the image forming apparatus 100.

[0061] In the image forming operation, the photosensitive drum 1 is driven by a motor M1 ( Figure 6 ) is driven and rotates at a predetermined speed (in this embodiment, 140 rpm) by Figure 1AThe charging roller 2 uniformly charges the surface of the rotating photosensitive drum 1 so that the surface potential (pre-exposure potential VD) becomes -800 V. The exposure unit 10 is driven according to the video signal sent by the control unit 90 based on the input image data, and irradiates the photosensitive drum 1 with laser light corresponding to 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 amount of light emitted by the exposure unit 10 is 0.45 μJ / cm 2 The laser light is applied to the photosensitive drum 1, so that the post-exposure potential VL (the potential in the bright portion) of the photosensitive drum 1 becomes -100V.

[0062] On the surface of the developing roller 4, a toner layer is formed from toner charged to a normal polarity. When a development voltage is applied to the developing roller 4, the toner is transferred from the developing roller 4 to the exposed areas of the surface 1a of the photosensitive drum 1 in the developing section 21. As a result, the electrostatic latent image on the surface 1a of the photosensitive drum 1 is developed, forming a toner image 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 development voltage.

[0063] In parallel with the toner image formation process described above, recording material P stored in a storage unit in the lower portion of image forming apparatus 100 is fed by a feed roller. When the toner image formed on photosensitive drum 1 reaches transfer unit N1, recording material P is conveyed to transfer unit N1. Furthermore, when the toner image formed on photosensitive drum 1 reaches transfer unit N1, a transfer voltage is applied to transfer roller 13. As a result, the toner image carried on photosensitive drum 1 is transferred to recording material P passing through transfer unit N1. In this embodiment, a DC voltage of +1500 V is applied to transfer roller 13 as the transfer voltage.

[0064] The recording material P to which the toner image has been transferred is conveyed to the fixing unit 14. The fixing unit 14 heats and pressurizes the toner image on the recording material P while gripping and conveying the recording material P at the fixing nip. As a result, the toner image is fixed to the recording material P. The recording material P that has passed through the fixing unit 14 is discharged to the outside of the image forming apparatus 100 by a pair of sheet discharge rollers and is stacked on a sheet discharge tray provided on the upper surface of the apparatus main body M.

[0065] In the present embodiment, transfer residual toner that has not been transferred to the recording material P in the transfer portion N1 and remains on the photosensitive drum 1 is collected by the developing roller 4 in the developing container 8. That is, the present embodiment adopts a so-called cleaner-less configuration (development-while-cleaning configuration) in which the toner that has not been transferred to the recording material P as a transfer object in the transfer portion N1 is collected by the developing member in the toner storage portion.

[0066] The surface area of ​​the photosensitive drum 1 after the transfer step receives the transfer current while passing through the transfer section N1, and thus the surface potential decreases. The surface potential of the photosensitive drum 1 after the transfer step in this embodiment (the potential of the unexposed area) is -150 V. The surface area of ​​the photosensitive drum 1 after the transfer step is neutralized by the neutralization section 11 so that the remaining surface potential becomes 0 V, and moves toward the charging section N2.

[0067] Transfer residual toner consists of a mixture of positively charged toner and negatively charged toner that lacks sufficient charge. After transfer, the photosensitive drum 1 is neutralized by the neutralization unit 11, and a uniform discharge is generated by the charging roller 2, allowing the transfer residual toner to be charged back to negative polarity. The transfer residual toner, negatively charged in the charging section N2, reaches the developing section 21 while the photosensitive drum 1 is rotating and is collected in the developing container 8 by the developing roller 4.

[0068] That is, the potential of the developing roller 4 (the DC component of the developing voltage, -400 V) is positive relative to the surface potential in the non-exposed area of ​​the photosensitive drum 1 (pre-exposure potential VD, -800 V), and is negative relative to the surface potential in the exposed area of ​​the photosensitive drum 1 (post-exposure potential VL, -100 V). Therefore, the transfer residual toner adhering to the non-exposed area of ​​the photosensitive drum 1 upon reaching the developing section 21 is transferred from the photosensitive drum 1 to the developing roller 4 in the developing section 21 and collected in the developing container 8. On the other hand, the transfer residual toner adhering to the exposed area of ​​the photosensitive drum 1 upon reaching the developing section 21 is not transferred to the developing roller 4 in the developing section 21 and remains on the photosensitive drum 1, and forms a toner image together with the toner newly supplied from the developing roller 4.

[0069] As described above, in this embodiment, the process unit 9 has a cleaner-less configuration in which transfer residual toner is collected and reused in the developing unit 20. The cleaner-less configuration of the process unit 9 eliminates the need for a space for a collection container for collecting transfer residual toner and the like, and the size of the image forming apparatus 100 can be further reduced. In addition, by reusing the transfer residual toner, the toner consumption rate can be suppressed, and printing costs can be reduced.

[0070] Toner

[0071] In this embodiment, a toner having a particle size of 6 μm is used, and the normal polarity (normal charging polarity) of the toner is negative. For example, the toner of this embodiment is a polymerized toner produced by a suspension polymerization method. In addition, the toner of this embodiment does not contain a magnetic component, and is a so-called non-magnetic single-component developer that is mainly carried on the developing roller 4 by intermolecular force or electrostatic force (mirror force). However, a single-component developer containing a magnetic component can be used as a developer (toner). In addition to the toner particles, the single-component developer may also contain additives (for example, wax or silica particles) for adjusting the fluidity and charging properties of the toner. In addition, the toner may contain an organic silicon polymer having a unit structure represented by the following formula (1) on the surface of the toner particles.

[0072] R-SiO 3 / 2 (1)

[0073] Here, in formula (1), R is an alkyl group or a phenyl group having 1 or more and 6 or less carbon atoms. By including the organosilicon polymer, protrusions are formed on the surface of the toner particles, and the performance of the toner is improved.

[0074] As a developer, a two-component developer containing a non-magnetic toner and a magnetic carrier can be used. When using a magnetic developer, for example, a cylindrical developing sleeve equipped with a magnet is used as a developer carrying member. Furthermore, the developing unit 20 may be a non-contact developing type in which the developing unit 20 is arranged with a predetermined gap from the photosensitive drum 1.

[0075] Developer container and toner pack

[0076] Next, the developing container 8 and the toner pack 40 serving as a replenishing container in this embodiment will be described. Figure 2A is a perspective view illustrating a process unit 9 including a developing container 8 and a toner pack 40, and Figure 2B 1 is a front view illustrating the process unit 9 and the toner pack 40 . Figure 3A It is along Figure 2B A cross-sectional view taken along line 40A-40A in FIG. Figure 3B It is along Figure 2B A cross-sectional view taken along line 40B-40B in FIG.

[0077] like Figure 2A 、 Figure 2B 、 Figure 3A and Figure 3B, the storage chamber 8a of the developing container 8 extends substantially over the entire length of the developing container 8 in the longitudinal direction of the developing unit 20 (the direction of the rotation axis of the developing roller 4). In addition, the developing container 8 has a protruding portion 37 as a protruding portion that protrudes upward from one end portion of the storage chamber 8a in the longitudinal direction and communicates with the storage chamber 8a.

[0078] An attachment portion 57 to which the toner pack 40 can be attached is provided at the upper end portion (top end portion) of the protruding portion 37. The attachment portion 57 has a replenishment port 32a that enables toner replenishment 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 replenishment port 32a, thereby allowing toner to move from the toner pack 40 to the storage chamber 8a.

[0079] The toner pack 40 is attached to the attachment portion 57 (see FIG. 1 ) in a state where at least a portion of the toner pack 40 is exposed to the outside of the image forming apparatus 100. Figure 1B ). For example, the user can expose the attachment portion 57 by opening the opening / closing member 101 provided on the upper surface of the apparatus body M, and 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. That is, the attachment portion 57 is configured to allow toner replenishment from the toner pack 40 to the developing container 8 in a state where at least a portion of the toner pack 40 is outside the image forming apparatus 100.

[0080] The developer container 8 is configured so that the toner input into the replenishment port 32a reaches the stirring member 7 solely by its own weight. The phrase "by its own weight" here means that the toner moves along the path from the replenishment port 32a to the stirring member 7 primarily by gravity, without receiving any force from a toner conveying member (screw, etc.), to which a driving force is supplied from a drive source such as a motor. The stirring member 7 is a rotating member closest to the replenishment port 32a and is arranged to supply the toner in the storage chamber 8a toward the developing roller 4 or the supply roller 5 by rotating.

[0081] The developing container 8 has a grip portion 39 ( Figure 2A and Figure 2B The grip portion 39 has a handle portion 39 a that a user can grip with their fingers. The handle portion 39 a is formed to protrude upward from the top surface of the grip portion 39 .

[0082] The protrusion 37 is formed to be hollow inside, and a replenishment port 32 a is formed in an upper surface thereof. The replenishment port 32 a is configured to be connectable to the toner pack 40 .

[0083] The toner pack 40 is attachable to and detachable from the attaching portion 57 provided in the protruding portion 37. The toner pack 40 includes a shutter member 41 capable of opening and closing a sheet discharge port of the main body of the toner pack 40, and a plurality of (in this embodiment, three) protrusions 42 formed corresponding to the plurality of (in this embodiment, three) groove portions 32b formed in the attaching portion 57. When replenishing the developing container 8 with toner, the user attaches the toner pack 40 to the attaching portion 57 by aligning the plurality of protrusions 42 of the toner pack 40 so as to pass through the plurality of groove portions 32b of the attaching portion 57.

[0084] When the toner pack 40 attached to the attachment portion 57 rotates 180 degrees, the shutter member 41 of the toner pack 40 abuts against an abutting portion (not shown) of the attachment portion 57, thereby rotating relative to the main body of the toner pack 40 and moving from a closed position to an open position. The closed position is a position in which the shutter member 41 closes the sheet discharge port, and the open position is a position in which the shutter member 41 retracts to open the sheet discharge port. As a result, the sheet discharge port and the replenishment port 32a communicate with each other, and the toner stored in the toner pack 40 flows downward into the protruding portion 37 via the sheet discharge port and the replenishment port 32a. The shutter member 41 may be provided on the side of the replenishment port 32a (the side of the apparatus main body M).

[0085] The protruding portion 37 has an inclined surface 37a at a position vertically facing the replenishing port 32a (a position below the replenishing port 32a). The inclined surface 37a is inclined downward toward the storage chamber 8a (toward the rotation axis of the stirring member 7). Therefore, the toner supplied to the developing container 8 through the replenishing port 32a is guided to the storage chamber 8a by the inclined surface 37a.

[0086] like Figure 3A and Figure 3B As shown in FIG, the stirring member 7 includes a stirring shaft 7a extending in the longitudinal direction of the developing unit 20 and a blade portion 7b fixed to the stirring shaft 7a and projecting radially outward relative to the stirring shaft 7a. The blade portion 7b is a flexible sheet. The stirring member 7 rotates around the stirring shaft 7a.

[0087] The toner replenished from the replenishment port 32a disposed upstream of the stirring member 7 in the conveying direction is fed toward the developing roller 4 and the supply roller 5 while the stirring member 7 is rotating. When viewed in the longitudinal direction of the developing unit 20 (the direction of the rotation axis of the developing roller 4), the stirring member 7 conveys the toner in the direction from the replenishment port 32a toward the developing roller 4. The stirring member 7 can also convey the toner in the longitudinal direction. The replenishment port 32a and the protruding portion 37 are disposed at one end of the developing container 8 in the longitudinal direction, but by repeating the rotation of the stirring member 7, the toner is diffused throughout the developing container 8 in the longitudinal direction. Instead of the stirring member 7 having the stirring shaft 7a and the blade portion 7b, for example, a spiral stirring member (a screw or a coil spring) may be used to convey the toner.

[0088] like Figure 4 and Figure 5A As shown in FIG, the toner pack 40 used as the replenishing container of the present embodiment has a toner storage portion formed of a plastic bag member that is easily deformed. The replenishing container is not limited thereto, and for example, a toner pack 40 may be used. Figure 5B The substantially cylindrical bottle container 40B shown in FIG. Figure 5C The material and shape of the supplementary container are not particularly limited.

[0089] In addition, as a method for discharging toner from the toner pack, if the replenishing container is toner pack 40 or paper container 40C, it is preferred that the user squeeze the toner with their fingers. If the replenishing container is bottle container 40B, it is preferred that the user tap the container, for example, to cause vibration, causing the toner to leak out. Furthermore, to discharge the toner from bottle container 40B, a discharge mechanism may be provided in bottle container 40B to discharge the toner independently of the weight of the toner. The discharge mechanism may be a piston that slides relative to the cylindrical portion (barrel portion) of bottle container 40B. Furthermore, the discharge mechanism may be engaged with the device body M to receive a driving force from the device body M.

[0090] In addition, the shutter member 41 may be omitted in any of the replenishing containers (40, 40B, 40C), and a sliding shutter member may be applied instead of the rotating shutter member 41. In addition, the shutter member 41 (sealing member) may be destroyed by attaching the replenishing container to the attaching portion 57 or rotating the toner pack in the attached state, or may have a detachable capping structure such as a seal.

[0091] As described above, in this embodiment, a toner replenishment type is employed in which toner can be replenished from outside the image forming apparatus 100 to the developing container 8 (toner storage portion) inside the apparatus using a toner pack 40. In the cartridge type, each time the toner runs out, the toner cartridge storing the toner, the developing unit 20 (developer cartridge) including the developing roller 4, or the process unit 9 (process cartridge) including the photosensitive drum 1 and the developing roller 4 is completely replaced. On the other hand, in the toner replenishment type, only the toner needs to be replenished to the developing container 8, and the environmental load can be reduced compared to the cartridge type.

[0092] Control system for image forming apparatus

[0093] Figure 6 is a block diagram illustrating a control system of image forming apparatus 100. Image forming apparatus 100 includes a control unit 90 that controls the operation of image forming apparatus 100. Control unit 90 includes a CPU 91 serving as a computing device, a RAM 92 serving as a work area for CPU 91, and a ROM 93 storing various programs. Furthermore, control unit 90 includes an I / O interface 94 serving as an input / output port for connecting to external devices.

[0094] The attachment sensor 53 is connected to the input side of the control unit 90. The attachment sensor 53 is an example of a detection unit for detecting attachment and detachment (at least one of attachment and detachment) of the toner pack 40 to and from the attachment portion 57. The attachment sensor 53 is, for example, a pressure-sensitive switch provided in the replenishment port 32a to output a detection signal when pressed by the protrusion 42 of the toner pack 40. When the toner pack 40 is detached after being attached, based on the detection signal of the attachment sensor 53, the control unit 90 can grasp that toner replenishment has been performed.

[0095] The control unit 90 is connected to the operating unit 300, the image forming unit 60, the remaining amount display unit 400 and the power supply board 70. The operating unit 300 (operation panel) includes 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 or physical keys of the display unit 301. The image forming unit 60 includes a motor M1 serving as a drive source and an exposure unit 10. The motor M1 of this embodiment is a common drive source for the photosensitive drum 1, the developing roller 4, the supply roller 5, the stirring member 7, etc. Note that the photosensitive drum 1, the developing roller 4, the supply roller 5 and the stirring member 7 can be driven by separate motors. The exposure unit 10 irradiates the photosensitive drum 1 with laser light modulated based on a video signal sent from the control unit 90 to perform an exposure step.

[0096] The power supply board 70 is connected to an external commercial power source to supply power for driving the control unit 90, the motor M1, etc., and outputs a high voltage for application to the charging roller 2, the developing roller 4, the 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.

[0097] The remaining amount display unit 400 is a display unit that displays information (remaining amount information) related to the remaining toner amount of the developing container 8 (toner storage portion). 7A to 7C The remaining amount display panel 401 is shown as an example of the remaining amount display unit 400. The remaining amount display panel 401 includes a plurality of (in this embodiment, three) lamps 401a, 401b, and 401c. The remaining amount display panel 401 is disposed on, for example, the front surface of the device body M (the surface on the downstream side in the direction in which the recording material is discharged from the device body M). The remaining amount display panel 401 displays information about the remaining amount of the toner according to the on / off state of the plurality of lamps 401a to 401c or the lighting pattern of the plurality of lamps 401a to 401c.

[0098] The remaining amount display panel 401 of the present embodiment has a function as a scale (indicator) that increases or decreases the number of lamps to be turned on according to the remaining toner amount of the developing container 8. The low level lamp 401c corresponds to the lowest remaining toner amount level (low level) among a plurality of remaining toner amount levels that can be displayed on the remaining amount display panel 401. The middle level lamp 401b corresponds to an intermediate remaining toner amount level (middle level), and the high level lamp 401a corresponds to the highest remaining toner amount level (full level).

[0099] That is, when the remaining toner amount of the developing container 8 is equal to or less than the first threshold value, as shown in FIG. Figure 7A As shown in FIG, only the low level lamp 401c is turned on, and the other lamps 401a and 401b are turned off. This display state indicates that the toner in the developing container 8 is almost exhausted (close to empty) or that the toner can be replenished. For example, by setting the remaining amount display panel 401 to Figure 7A In the display state of , the control unit 90 may perform an operation of notifying the user of information for prompting toner replenishment (toner replenishment notification).

[0100] When the remaining toner amount of the developing container 8 is equal to or greater than a second threshold value which is larger than the first threshold value, as shown in FIG. Figure 7CAs shown in FIG, all the lamps 401a to 401c are turned on. This display state indicates that the current remaining toner amount relative to the amount of toner that can be stored in the developing container 8 is 100% or close to 100% (full state). When the remaining toner amount of the developing container 8 is greater than the first threshold value and less than the second threshold value, as shown in FIG. Figure 7B , the low level lamp 401b and the medium level lamp 401c are turned on, and the high level lamp 401a is turned off. This display state indicates that the toner in the developing container 8 is between a nearly empty state and a full state.

[0101] It is noted that the specific configuration of the remaining quantity display panel 401 and the remaining quantity information display mode are not limited to those described above. The number of lamps can also be one, two, or four or more. The lighting mode that each lamp can take is not limited to two modes: on mode and off mode, and can be a combination of a flashing mode, a light quantity change mode, a light color change mode, etc.

[0102] In addition, the remaining amount display unit 400 is not limited to the remaining amount display panel 401 using a lamp, and may be configured to display the remaining amount of the battery as shown in FIG. Figure 8 The remaining amount display unit 400 in this case may be the operation unit 300 (operation panel) of the image forming apparatus 100, or may be an external device (such as a user's personal computer) communicably connected to the image forming apparatus 100.

[0103] Figure 8 The screen display includes a rod-shaped gauge G1 that changes continuously from 0% to 100% and a numerical value G2 (63%) indicating the remaining colorant amount as remaining amount information indicating the remaining colorant amount of the developing container 8. The illustrated example indicates that the remaining colorant amount is 63%. That is, in this embodiment, the remaining amount of the colorant changes from 100% to 0% as the colorant is consumed. The remaining amount information displayed on the screen by the remaining amount display unit 400 is not limited to this, and only one of the gauge G1 and the numerical value G2 may be displayed. In addition, for example, instead of the gauge G1, an image that changes step by step according to the remaining colorant amount level may be used. In addition, the control unit 90 may use the operating unit 300 to perform a toner replenishment notification. The information displayed on the display unit 301 of the operating unit 300 in the toner replenishment notification may be, for example, a text message, a voice message, or a buzzer sound. In addition, the remaining amount of the toner may be continuously changed from 0% to 100% based on the toner usage amount (toner consumption amount).

[0104] Point counting method

[0105] The control unit 90 according to the present embodiment calculates the toner consumption amount and the remaining toner amount of the developing container 8 by a dot counting method (pixel counting method). The dot counting method is a method of calculating the toner consumption amount when forming an image or the remaining toner amount after image formation based on a count value corresponding to the number of pixels constituting the image formed on the recording material P (hereinafter referred to as a dot count value).

[0106] As a mechanism for the control unit 90 of the image forming apparatus 100 to grasp the remaining toner amount, in addition to the dot counting method that calculates the remaining toner amount using software, there are also methods using sensors for detecting the remaining toner amount (sensor methods and hardware detection methods). Sensor types include light detection, capacitance, and weight types. The dot counting method is superior to the sensor method because it is low-cost, has no restrictions on hardware configuration, and its calculation accuracy does not depend on the amount of remaining toner.

[0107] Here, the control unit 90 performs image processing by analyzing image data received from the outside and developing the image data into a raster image, which is data in a raster format. Based on the developed raster image, the control unit 90 transmits a video signal to the exposure unit 10. This video signal is a time-series signal that specifies whether each pixel is to be exposed and the amount of light during exposure. The exposure unit 10 exposes or does not expose the area corresponding to each pixel on the photosensitive drum 1 using the amount of light corresponding to the value of the video signal.

[0108] The dot count value may be calculated using data or signals at any stage in the image forming operation, as long as the dot count value is a numerical value related to the number of pixels constituting the image formed on the recording material P. In the present embodiment, based on the raster image developed by the control unit 90, the number of dots constituting the raster image (the number of pixels to be developed for the toner image, the number of print pixels) is set as the dot count value.

[0109] Without limitation, the dot count value may be a numerical value indicating the cumulative number of times or cumulative emission time of the light source 10a in the exposure unit 10. For example, the light emission of the laser element, which is the light source 10a of the exposure unit 10 in this embodiment, may be monitored, and the count result of a counter (counting circuit) that counts the number of pixels from which the laser element emits light may be used as the dot count value. The counter may be provided on the semiconductor substrate that drives the laser element (i.e., as part of the exposure unit 10). Furthermore, the counter may be provided in the control unit 90 to calculate the integral value of the value of the video signal sent to the exposure unit 10. The value obtained by measuring the cumulative emission time of the laser element may be used as the dot count value.

[0110] In addition, the dot count value may be counted as a binary value of "0 (toner image not developed)" or "1 (toner image developed)" for each pixel, or the maximum count value for each pixel may be allowed to be greater than 1. For example, in a case where the exposure amount of one pixel is controlled to one of five levels from 0% to 100% in increments of 20% by turning on / off the light source 10a for each area obtained by dividing one pixel into four areas, the count value for each pixel is set to one of five levels from "0" to "4" in increments of 1. In this case, the maximum value of the dot count value when printing one image is four times the number of pixels in the effective image area (the maximum area in which a toner image can be formed on the photosensitive drum 1). In addition, for example, the count value for each pixel may be allowed to be a decimal number.

[0111] Furthermore, for example, the dot count value may be a value obtained by sampling and counting some of the data to be counted (the number of dots in the raster image or the cumulative number of times the light source 10a emits light) in order to reduce the processing load. That is, the dot count value does not need to strictly coincide with the number of pixels constituting the image to be formed on the recording material P, and only needs to be calculated as a numerical value related to the number of pixels constituting the image to be formed on the recording material P.

[0112] In this embodiment, the control unit 90 may calculate the dot count value. However, the counting circuit that calculates the dot count value may be arranged in a circuit different from the control unit 90.

[0113] Remaining toner amount and remaining toner amount indicator

[0114] refer to Figure 9A and Figure 9B , the relationship between the remaining toner amount in the developing container 8 and the remaining toner amount indication when a predetermined image is repeatedly printed by the image forming apparatus 100 according to the present embodiment will be described. Figure 9A In the graph of , the horizontal axis represents the number of printed sheets, and the vertical axis represents the remaining toner amount Q (g) in the developing container 8. Test images are repeatedly printed based on test image data in which halftones and text are mixed at an image coverage rate of 4%. It is assumed that the dot count value in each image forming operation is constant. Figure 9A In FIG. 1 , Qfull represents the value of the remaining toner amount Q immediately after toner replenishment, and Qout represents a predetermined threshold value of the remaining toner amount Q at which toner replenishment to the developing container 8 needs to be performed. Figure 8 In the case where the remaining toner amount is displayed by a continuous gauge as illustrated in FIG, “100%” is displayed when Q=Qfull, and “0%” is displayed when Q=Qout. As described above, the remaining toner amount indication may be as follows: 7A to 7C Step-by-step instructions are shown in the figure.

[0115] The dot count value of each test image is defined as C, the toner consumption when printing one test image is defined as T(g), and the coefficient for calculating the toner consumption T is defined as k. The control unit 90 of this embodiment calculates T according to the following formula (2).

[0116] T=k·C (2)

[0117] The above formula (2) is an example of a function (T=f(C)) representing the toner consumption amount T using the dot count value C as a variable. The function f(C) may be different from the formula (2).

[0118] Each time a test image is printed from the state where Q = Qfull, the control unit 90 subtracts the toner consumption amount T from the value of the remaining toner amount Q. When the remaining toner amount Q becomes equal to or less than Qout, the control unit 90 causes the remaining amount display unit 400 to display 0% and notifies the user to initiate toner replenishment without accepting any further image forming operations. Hereinafter, the point in time when the remaining toner amount Q becomes Qout is referred to as "immediately before toner replenishment," and the point in time when toner is replenished from the state immediately before toner replenishment and the remaining toner amount becomes Qfull is referred to as "immediately after toner replenishment."

[0119] Here, in this embodiment, as a countermeasure against the change in the toner consumption rate due to toner replenishment, the value of the coefficient k is changed when toner is supplied. The change in the toner consumption rate means that the toner consumption amount T differs when an image is formed based on the same image data immediately before and immediately after toner replenishment (that is, when the dot count value C of one image is the same).

[0120] The reason for the change in toner consumption rate due to toner replenishment can be described as follows. In the toner of this embodiment, in an unused (fresh) state, many charged sites exist on the toner surface, and the toner has high charging performance. These charged sites are primarily formed by additives (external additives) such as silica added to the toner.

[0121] On the other hand, the toner in developer container 8 immediately before toner replenishment is in a state where it is repeatedly used for image formation until the remaining toner amount Q decreases from Qfull to Qout. During image formation, the toner in developer container 8 is carried by developer roller 4 and rubs against developer blade 6, photosensitive drum 1, and supply roller 5. Furthermore, while stirring member 7 is rotating, the toner particles in developer container 8 rub against each other. For this reason, the toner in developer container 8 immediately before toner replenishment contains a high proportion of toner particles in a state where charging performance has deteriorated due to additives being embedded in the toner surface or transferred from the toner surface to another member.

[0122] When newly replenished toner with high charging performance (referred to as fresh toner) mixes with toner with a high ratio of toner particles in a state of degraded charging performance (referred to as degraded toner), charge transfer occurs between the fresh toner and the degraded toner due to the difference in charging performance. Therefore, the charge amount of the fresh toner tends to be greater than the charge amount when the fresh toner and the degraded toner are not mixed, and the charge amount of the degraded toner tends to be less than the charge amount when the degraded toner and the fresh toner are not mixed. Furthermore, fresh toner has higher fluidity than degraded toner and is more easily carried by the developing roller 4 than degraded toner. As a result, the average charge amount of the toner carried on the developing roller 4 immediately after toner replenishment is greater 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 performed is larger than the absolute value of the average charge amount of the toner carried on the developing member before toner replenishment is performed.

[0123] Since the amount of toner charge on the developing roller 4 is greater 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 after toner replenishment is less than that before toner replenishment. As a result, even if images are formed based on the same image data before and after toner replenishment, the toner consumption T per image after toner replenishment is less than the toner consumption T per image before toner replenishment.

[0124] Therefore, in the present embodiment, when toner replenishment is performed, the value of the coefficient k used for calculating the toner consumption amount T based on the dot count value C is changed to a value smaller than the value before toner replenishment.

[0125] 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, the value of the coefficient k after the Nth toner replenishment and before the (N+1)th toner replenishment with respect to the time point when the image forming apparatus is installed is defined as k n , and the value of the coefficient k after the (N-1)th toner replenishment and before the Nth toner replenishment is defined as k n-1 In this case, k n <k n-1 That is, in this embodiment, the value of the coefficient k is reduced every time toner replenishment is performed. In this embodiment, the value of the coefficient k is set so that, for example, the ratio k of the values ​​of the coefficient k before and after toner replenishment is n / k n-1 Falling within the range of 0.5 to 0.95.

[0126] In other words, when repeatedly performing an image forming operation based on the same image data (the dot count value C is constant), the control unit 90 changes the value of the coefficient k when performing colorant replenishment, so that the calculated result of the colorant consumption consumed in the image forming operation after performing the colorant replenishment is less than the calculated result of the colorant consumption consumed in the image forming operation before performing the colorant replenishment.

[0127] Figure 9B is a graph showing an example of changes in the remaining toner amount indication in the first embodiment. Figure 9B The diagram shows that when repeated printing and Figure 9A The relationship between the number of prints and the remaining toner amount indication when the same test pattern is printed.

[0128] As described above, in the first embodiment, when toner replenishment is performed, the value of the coefficient k decreases. As a result, the value calculated as the toner consumption amount T per test image after the Nth toner replenishment is performed is smaller than the value calculated as the toner consumption amount T per test image before the Nth toner replenishment is performed. That is, Figure 9B The slope D of the graph after the Nth toner replenishment is performed n The slope D of the graph before the Nth toner replenishment is performed is n-1 gentle.

[0129] Therefore, the value of the toner consumption amount T calculated based on the dot count value C can be made close to the actual toner consumption amount. In addition, the remaining toner amount ( Figure 9B ) is close to the actual remaining toner amount Q( Figure 9AIn addition, the timing when the actual remaining toner amount Q decreases to Qout is close to the timing when the calculated remaining toner amount decreases to Qout (the timing when the remaining toner amount indication becomes 0%). Therefore, the user can be notified of toner replenishment at a more appropriate timing.

[0130] In this embodiment, the value of the coefficient k decreases every time toner replenishment is performed. Figure 9B In the case where the printing of the test image is continued during the (N+1)th and subsequent toner replenishment periods, the relationship between the number of prints and the remaining toner amount indication is as follows: Figure 9C That is, every time toner replenishment is performed, the value of the toner consumption amount T calculated for each test image becomes smaller, and the slope of the graph becomes gentler.

[0131] When the number of printed sheets from the Nth toner replenishment to the (N+1)th toner replenishment is defined as P n hour,... <P n-1 <P n <P n+1 <P n+2 That is, when the image forming operation is repeatedly performed based on the same image data, as the number of toner replenishments increases, the number of printed sheets from the previous toner replenishment to the next toner replenishment increases (the interval between toner replenishments increases).

[0132] Comparative Example 1

[0133] As Comparative Example 1, it is assumed that the toner consumption T and the remaining toner amount Q are calculated without changing the value of the coefficient k even when toner replenishment is performed. The configuration of the apparatus and the calculation method of the toner consumption T and the remaining toner amount Q are the same as those in the first embodiment, except that the value of the coefficient k after the Nth toner replenishment is the same as that before the toner replenishment. Therefore, as Figure 9A As illustrated in FIG, transition of the actual remaining toner amount Q when the above-described test image is repeatedly output is consistent with that in the first embodiment.

[0134] On the other hand, the toner consumption amount T of each test image calculated based on the dot count value C in Comparative Example 1 does not change before and after the Nth toner replenishment. Figure 9B The dotted line in FIG indicates the slope D of the graph after the Nth toner replenishment. n The slope D of the graph before the Nth toner replenishment n-1 The same as that of the graph after the Nth toner replenishment in the first embodiment, and the inclination D is greater than that of the graph after the Nth toner replenishment in the first embodiment. n Relatively steeper.

[0135] As a result, the number of prints Pb calculated in Comparative Example 1, at which the remaining toner amount Q is 0%, is smaller than the number of prints Pa calculated in the first embodiment, at which the remaining toner amount Q is 0%. That is, in Comparative Example 1, even if a toner amount greater than Qout actually remains in the developer container 8 at the time of the number of prints Pb, a toner replenishment notification is executed. In contrast, according to this embodiment, a toner replenishment notification can be executed at or near the time of the number of prints Pa, at which the actual remaining toner amount Q in the developer container 8 is equal to or less than Qout.

[0136] Control methods

[0137] Figure 10 1 is a flowchart illustrating an example of a control method according to the present embodiment. Each step of this flow is implemented by the CPU 91 of the control unit 90 reading a program from the ROM 93 and executing the program. In addition, this flow is continuously processed during the period when the main power of the image forming apparatus 100 is on.

[0138] Whenever an image forming operation is performed (S1: "Yes"), the control unit 90 acquires the dot count value C of the image formed in the image forming operation (S2). The control unit 90 calculates the toner consumption T used to form the image based on the acquired dot count value C, and calculates the remaining toner amount Q in the developing container 8 after the image forming operation is performed (S3). Specifically, in this embodiment, the toner consumption T calculated is a value obtained by multiplying the dot count value C by a coefficient k, and the remaining toner amount Q after the image forming operation is a value obtained by subtracting the toner consumption T from the remaining toner amount Q before the image forming operation is performed.

[0139] If the remaining toner amount Q after the image forming operation is equal to or less than a preset threshold value (equal to or less than Qout) (S4 "Yes"), the control unit 90 performs a toner replenishment notification without accepting a new image forming operation and prompts the user to replenish the toner (S5). Thereafter, upon detecting that toner replenishment has been performed (S6 "Yes"), the control unit 90 changes the value of the coefficient k (S7), returns to the start, and waits for the next image forming instruction. In this embodiment, the control unit 90 determines that the toner has been replenished when it detects, based on the detection signal of the attachment sensor 53, that the toner pack 40 has been attached to the attachment portion 57 and then removed. On the other hand, if the remaining toner amount Q after the image forming operation is greater than the threshold value (Qout) (S4 "No"), the control unit waits for the next image forming instruction without performing a toner replenishment notification and without changing the value of the coefficient k.

[0140] The value of coefficient k after the Nth toner replenishment is defined as k n(n=1,2,3,…). In this embodiment, each k n The value of is considered in advance according to, for example, a specific toner manufacturing method and a specific configuration of the developing unit 20, and is stored as a preset value in the ROM 93 ( Figure 6 ) Every time toner replenishment is executed, the CPU 91 counts the number of toner replenishments and reads k corresponding to the number of toner replenishments so far from the ROM 93. n , to calculate the toner consumption T in the next image forming operation and subsequent image forming operations using the read value.

[0141] The value of coefficient k can be calculated, if necessary, based on the pattern of toner consumption during the period from one toner replenishment to the next. For example, the pattern of toner consumption can be expressed as the relationship between the average image coverage (the average image coverage of images output from the previous toner replenishment until the current time) and the degree of toner degradation. For example, when the average image coverage is high, toner is consumed earlier than toner degradation, and thus toner replenishment notification is performed earlier, while toner degradation is not progressing much. In this case, the value of coefficient k may not change during toner replenishment, or the change width may be smaller than when the average image coverage is low.

[0142] Overview of this embodiment

[0143] As described above, in this embodiment, when toner replenishment is performed, the value of the coefficient k used when calculating the toner consumption T based on the dot count value C is changed. As a result, even when the actual toner consumption changes when an image based on the same image data is formed before and after toner replenishment, the calculated toner consumption T can be made close to the actual toner consumption.

[0144] That is, according to this embodiment, the accuracy of calculating the toner consumption amount can be improved.

[0145] As described above, this embodiment employs a toner replenishment type (external replenishment type) in which toner is replenished from a toner pack 40 (replenishment container) outside the image forming apparatus 100 to the developer container 8 (toner storage portion) within the apparatus. In this toner replenishment type, it is important to accurately determine the remaining toner amount Q in the developer container 8, reflect this amount on the remaining amount display unit 400, and notify the user at an appropriate time to prompt toner replenishment. If the calculation accuracy of the remaining toner amount Q is low, for example, if a toner replenishment notification is issued even though the actual remaining toner amount Q is large and the user replenishes toner, there is a possibility that not all the toner in the toner pack 40 will be replenished into the developer container 8, and some toner will be wasted. Furthermore, if a toner replenishment notification is not issued even though the actual remaining toner amount Q is less than Qout, there is a possibility that image defects may occur or the developer roller 4 may be damaged due to depletion of toner in the developer container 8.

[0146] Furthermore, in this embodiment, a cleanerless configuration is employed in which transfer residual toner that has not yet been transferred to recording material P (the transfer target) in transfer section N1 is collected by developer roller 4 in developer container 8. In a cleanerless configuration, since some of the toner developed on photosensitive drum 1 is collected in developer container 8 via transfer section N1, charging section N2, and the like and reused for image formation, the proportion of degraded toner with degraded charging performance tends to be high. As a result, the mixture of fresh toner and degraded toner can easily cause an increase in the average charge of the toner on developer roller 4 and an accompanying change in toner consumption per image. Therefore, the present technique of varying the value of coefficient k used to calculate toner consumption T before and after toner replenishment can be particularly advantageous in a cleanerless configuration.

[0147] However, even in a configuration including a cleaning member that removes transfer residual toner between the transfer portion N1 and the charging portion N2, the toner itself deteriorates because the toner rubs against the stirring member 7 or the developing blade 6 in the developing container 8. Therefore, in an image forming apparatus that does not have a cleaner-less configuration, as in the present embodiment, the value of the coefficient k may be changed when replenishing the toner.

[0148] Modification example when the value of coefficient k increases

[0149] In the first embodiment, it has been described that when toner replenishment results in a mixture of fresh toner and deteriorated toner, the average charge amount of the toner on the developing roller 4 becomes larger than the average charge amount before toner replenishment, and the toner consumption amount per test image becomes smaller than the toner consumption amount before toner replenishment. However, toner replenishment can reduce the average charge amount of the toner on the developing roller 4 compared to before toner replenishment, and as a result, the toner consumption amount per test image can increase compared to before toner replenishment.

[0150] For example, when the charging properties of the base material (base resin) of the toner particles are very strong and it is difficult to control the developability and transferability, an additive that suppresses the charging properties of the toner can be added. Specifically, the charge amount can be suppressed by using a low-resistance additive to release the charge from the base material of the toner particles, or by using a slightly higher-resistance additive to reduce the contact area with the toner or each component. In this case, because the additive is embedded in the toner surface or transferred from the toner surface to another component due to repeated use in image formation, the toner immediately before toner replenishment is in a state of improved charging properties compared to fresh toner. On the other hand, because the charging properties are suppressed by the additive and the fluidity is high, the fresh toner supplied by toner replenishment tends to be preferentially carried on the developer roller 4. As a result, the average charge amount of the toner on the developer roller 4 immediately after toner replenishment becomes smaller than that immediately before toner replenishment.

[0151] In this case, when toner is replenished into 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. That is, the value of the coefficient k after the Nth toner replenishment and before the (N+1)th toner replenishment is defined as k n , and the value of the coefficient k after the (N-1)th toner replenishment and before the Nth toner replenishment is defined as k n-1 In this case, in this modification, the value of the coefficient k is changed so that k n >k n-1 As a result, also in this modification, the toner consumption amount calculation accuracy can be improved.

[0152] In this modification, when the test images are repeatedly printed based on the same image data, the interval of toner replenishment ( Figure 9C P in n-1 、P n 、P n+1 ...) has the following relationship: ...>P n-1 >P n >P n+1 >P n+2>... is satisfied.

[0153] The value of the coefficient k after toner replenishment compared to the value before toner replenishment can be appropriately adjusted by the designer of the image forming apparatus 100 after understanding the characteristics of the toner and the apparatus.

[0154] Modification of Detection of Toner Replenishment

[0155] The attachment sensor 53 of this embodiment is merely an example of a detection unit for detecting toner replenishment from the toner pack 40 (replenishment container). For example, when toner replenishment is complete, the user can operate the operation unit 300 to input the completion of toner replenishment, and the control unit 90 can detect toner replenishment based on the information from the operation unit 300. When toner replenishment is complete, the user can operate an external computer communicably connected to the image forming apparatus 100 to input the completion of toner replenishment, causing the control unit 90 to detect toner replenishment. In this case, the receiving unit (external interface) in the operation unit 300 or the control unit 90 that receives a signal from the external computer is an example of a detection unit for detecting toner replenishment. In the case where a tag (storage medium) is attached to the toner pack 40 and the toner pack 40 is attached to the attachment portion 57, the control unit 90 can detect toner replenishment by reading information from the tag.

[0156] Second embodiment

[0157] As a second embodiment, a description will be given of a case where the charging voltage and / or the developing voltage is changed when toner replenishment is performed. Hereinafter, unless otherwise specified, elements denoted by the same reference numerals as those in the first embodiment have substantially the same configurations and operations as those described in the first embodiment, and primarily the differences from the first embodiment will be described.

[0158] The reason for changing the charging voltage and / or developing voltage when performing toner replenishment is to improve fogged images. Fogging is an image defect in which toner thinly adheres to the surface areas (non-exposed areas) of the photosensitive drum 1 where a toner image should not be developed, resulting in a thin image being formed in areas (white portions) of the recording material P where an image should not be formed. Toner that adheres to the non-exposed areas of the surface area of ​​the photosensitive drum 1 that has passed through the developing unit 21 is called fogged toner.

[0159] One of the causes of fogged images is contamination of the charging roller 2, which degrades the charging performance. This causes the pre-exposure potential VD, which is the surface potential of the photosensitive drum 1 after the charging step, to be lower (the absolute value becomes smaller) than the designed value (in this embodiment, -800 V). When the pre-exposure potential VD decreases, 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 section 21, and some of the toner on the developing roller 4 moves to the non-exposed area of ​​the photosensitive drum 1 and becomes fogged toner.

[0160] One cause of contamination of the charging roller 2 is toner degradation, which increases the amount of toner particles that enter the charging portion N2 (the nip between the charging roller 2 and the photosensitive drum 1). Specifically, during repeated use for image formation, toner additives may become embedded in the toner surface or toner particles may become deformed due to friction with the developing blade 6 and other components, potentially increasing toner adhesion to the photosensitive drum 1. Increased toner adhesion to the photosensitive drum 1 increases the likelihood of residual toner being transferred, and the amount of residual toner that reaches the charging portion N2 increases. Furthermore, increased toner adhesion to the photosensitive drum 1 itself can contribute to the susceptibility of toner fogging.

[0161] In a state where the amount of fogged toner and transfer residual toner is small, even if the toner adheres to the charging roller 2, the toner is charged to a negative polarity by frictional electrification caused when the photosensitive drum 1 and the charging roller 2 rub against each other in the charging portion N2, and gradually returns to the photosensitive drum 1. When the amount of fogged toner and transfer residual toner increases, the speed at which the toner adheres to the charging roller 2 increases, and the toner adhering to the charging roller 2 may not be sufficiently removed by the above-mentioned mechanism, resulting in the gradual accumulation of dirt.

[0162] Therefore, when the ratio of non-degraded fresh toner on the developing roller 4 is increased by replenishing the toner, the occurrence of fog toner and transfer residual toner is reduced, and the contamination of the charging roller 2 can be improved.

[0163] In this embodiment, it is proposed to further reduce the fogged colorant and further improve the fogged image by increasing the charging voltage when performing colorant replenishment. The increase in the charging voltage means increasing the absolute value of the DC component of the charging voltage. When the charging voltage is increased, the surface potential of the photosensitive drum 1 after the charging step (pre-exposure potential VD) increases. As a result, in the developing part 21, the potential difference Vback between the surface potential (pre-exposure potential VD) in the non-exposed area of ​​the photosensitive drum 1 and the potential of the developing roller 4 (DC component of the developing voltage) increases. The potential difference Vback is used to prevent the colorant charged to the normal polarity from moving from the developing roller 4 to the non-exposed area of ​​the photosensitive drum 1, and can therefore be called a fog prevention contrast.

[0164] Figure 11 The diagram illustrates an example of controlling the charging voltage and developing voltage according to this embodiment. The control unit 90 of this embodiment changes the charging voltage from -1400 V to -1500 V at the timing of toner replenishment. As a result, the pre-exposure potential VD of the portion of the photosensitive drum 1 not affected by contamination of the charging roller 2 changes from -800 V to approximately -900 V, while the pre-exposure potential VD of the portion affected by contamination of the charging roller 2 is higher (larger in absolute value) than before the change in charging voltage. On the other hand, in the illustrated example, the developing voltage is held constant at -400 V before and after toner replenishment. In this case, in the portion of the photosensitive drum 1 not affected by 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, in the portion of the photosensitive drum 1 affected by contamination of the charging roller 2, the absolute value of the potential difference Vback after toner replenishment is greater than the absolute value of the potential difference Vback before toner replenishment. In this way, by increasing the absolute value of the potential difference Vback, sufficient pre-exposure potential VD and potential difference Vback can be ensured even in the presence of a portion where charging performance deteriorates due to contamination of the charging roller 2, thereby further reducing fogged colorant and improving fogged images.

[0165] Although Figure 11 While the example in which the charging voltage increases when toner replenishment is shown, the developing voltage may decrease (the absolute value may decrease) when toner replenishment is performed. Alternatively, the charging voltage may increase, and the developing voltage may decrease. In either case, the potential difference Vback increases after toner replenishment compared to before toner replenishment, thus achieving advantages similar to those of this embodiment.

[0166] In this manner, when toner replenishment is performed, the control unit 90 changes at least one of the charging voltage (first voltage) and the developing voltage (second voltage). Specifically, the surface potential (pre-exposure potential VD) of the photosensitive drum 1 after being charged by the charging roller 2, which is applied with the charging voltage (first voltage), is defined as the first potential, and the potential of the developing roller 4, to which the developing voltage (second voltage) is applied, is defined as the developing potential (second potential). In this case, when toner replenishment is performed, 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.

[0167] The charging voltage and / or the developing voltage may be changed each time toner replenishment is performed, or when toner replenishment is performed a predetermined number of times from the time the image forming apparatus 100 is installed. Furthermore, for example, a trigger for changing the charging voltage and / or the developing voltage may be a detection signal from the attachment sensor 53 as in the first embodiment. This trigger may be operating the operating unit 300 or an external computer to input toner replenishment completion, or reading information from a label on the toner pack 40.

[0168] In this embodiment, the potential difference Vback increases before and after toner replenishment. When the potential difference Vback increases, the toner consumption decreases, especially at the edges of lines or text in the image and in the halftone area. The reason for this can be explained as follows.

[0169] In the development step, the toner image is developed with the toner adhering to the area on the side (closer to 0V) where the potential of the surface of the photosensitive drum 1 is lower than the development potential (DC component of the development voltage). On the other hand, the potential distribution of the latent image formed in the exposure step does not rise vertically from the pre-exposure potential VD to the post-exposure potential VL, but rises at a certain degree of inclination. Therefore, when the potential difference Vback increases, the area on the side where the potential is lower than the development potential becomes narrower, and the toner adhering to the surface of the photosensitive drum 1 decreases. Since the above-mentioned mechanism occurs at the edge of the latent image, it is more likely to occur in an image with an edge (an image containing a line drawing or text composed of lines) than in a solid image without an edge, and is particularly more prominent in a halftone area with a high edge density.

[0170] As described above, in this embodiment, since the potential difference Vback increases in addition to the change in the average charge amount of the toner carried on the developing roller 4 before and after toner replenishment, the toner consumption rate after toner replenishment is further reduced compared to the first embodiment. However, in this embodiment, by reducing the value of the coefficient k in consideration of the influence of the increase in the potential difference Vback when toner replenishment is performed, it is possible to appropriately cope with the change in the toner consumption rate.

[0171] Therefore, according to the present embodiment, it is possible to enhance the accuracy of calculating the toner consumption amount T based on the dot count value C. Figure 9A and Figure 9B , the relationship between the actual remaining toner amount and the remaining toner amount indication can be correctly maintained.

[0172] In the case where toner replenishment is repeated when a test image based on the same image data is repeatedly printed by the image forming apparatus 100 of the present embodiment, for example, as shown in FIG. Figure 12The behavior illustrated in FIG. In this example, when performing the Nth toner replenishment, the charging voltage is changed to increase the potential difference Vback and decrease the value of the coefficient k. When performing the (N-1)th toner replenishment and the (N+1)th toner replenishment, the charging voltage and the value of the coefficient k are unchanged.

[0173] In this case, due to the influence of the change in the average charge amount of the toner and the increase in the potential difference Vback, the actual toner consumption of each test image after the Nth toner replenishment is less than that before the Nth toner replenishment. On the other hand, the value of the coefficient k after the Nth toner replenishment is changed to a smaller value than that before the Nth toner replenishment. Therefore, after the Nth toner replenishment is performed, the toner consumption of each test image calculated based on the dot count value C decreases, and the slope of the graph becomes gentle. When the number of printed sheets from the Nth toner replenishment to the (N+1)th toner replenishment is defined as P n When P n-2 =P n-2 <P n =P n+1 .

[0174] Note that in this embodiment, an example has been described in which the charging voltage and / or the developing voltage are changed so that the potential difference Vback increases when toner replenishment is performed compared to before toner replenishment is performed. Without limitation, the charging voltage and / or the developing voltage may be changed so that the potential difference Vback decreases compared to before toner replenishment is performed. In this case, the value of the coefficient k after toner replenishment may be changed to a value greater than that before toner replenishment. As an example of a case where the potential difference Vback decreases, as in the first embodiment, there is a case where it is desired to prevent an overall decrease in image density due to toner replenishment (which increases the average charge of the toner on the developing roller 4), thereby causing the image of thin lines or small dots to become thinner or lighter.

[0175] First Modification

[0176] Immediately after toner replenishment, the mechanism described in the first embodiment increases the average charge of the toner on the developing roller 4 and reduces the toner consumption rate. However, as the number of printed sheets increases, the difference in properties between the toner replenished by the immediately preceding toner replenishment and the old toner present in the toner container 8 before the immediately preceding toner replenishment is reduced. As a result, the toner consumption rate can be restored to the same level as before the immediately preceding toner replenishment.

[0177] This modification proposes a configuration capable of coping with a situation in which the toner consumption speed increases at a stage in which the number of printed sheets increases to a certain extent after toner replenishment compared to immediately after toner replenishment.

[0178] Figure 13A Graph 1 is a graph showing the transition of the remaining toner amount Q in the developing container 8 in this modified example. When toner replenishment is repeatedly performed while repeatedly printing test images based on the same image data, the rate of decrease of the remaining toner amount Q immediately after the Nth toner replenishment is lower than that before the toner replenishment. On the other hand, for the reasons described above, when the number of printed sheets increases to a certain extent since the Nth toner replenishment, the rate of decrease of the remaining toner amount Q increases to the same level as before the Nth toner replenishment.

[0179] Figure 13B : is a graph showing the transition of the remaining toner amount in the remaining amount display unit 400. In this modification, from immediately after the Nth toner replenishment until a predetermined number of images are output (until the cumulative number of printed sheets reaches Pc), the value of the coefficient k (k n ). However, after a predetermined number of images are output from immediately after the Nth toner replenishment, the value of the coefficient k is returned to the same value as that immediately before the Nth toner replenishment. Therefore, from immediately after the Nth toner replenishment until the predetermined number of images are output, the inclination D of the remaining toner amount calculated based on the dot count value C is n than the inclination D immediately before the Nth toner replenishment n-1 On the other hand, after a predetermined number of images are output, the inclination D of the remaining toner amount calculated based on the dot count value C is n ″ becomes the same as the inclination D immediately before the Nth toner replenishment n-1 Basically the same.

[0180] In other words, after the current toner replenishment is performed, the value of the coefficient k is changed to a first value (k ) which is smaller than the value of the coefficient before the current toner replenishment is performed. n-1 ) Small second value (k n ), and thereafter, before the next toner replenishment is performed, the control unit 90 changes the value of the coefficient to a value greater than the second value (k n )The third value (k n-1 ). In this embodiment, it has been described that the third value is the same as the first value, that is, the value of the coefficient k is changed from k n-1 Change to k n Then return to k n-1 , but the third value may be different from the first value.

[0181] By executing the above control, the remaining toner amount calculated based on the dot count value C becomes equal to or less than Qout (0%) at substantially the same timing as the number of printed sheets Pd at which the actual remaining toner amount Q becomes equal to or less than Qout. Therefore, even if the toner consumption rate increases when the number of printed sheets increases to a certain extent after toner replenishment, toner replenishment notification can be executed at appropriate timing.

[0182] In the second embodiment, the toner consumption rate may increase when the potential difference Vback increases for a certain period of time after toner replenishment is performed and returns to its original value after a period of time has passed in which dirt on the charging roller 2 has been removed. Therefore, when toner replenishment is performed in the second embodiment, control can be performed to change the charging voltage and / or the developing voltage, and then return the charging voltage and / or the developing voltage to their base values. In other words, the control unit 90 can change at least one of the charging voltage (first voltage) and the developing voltage (second voltage) to increase the potential difference Vback after the current toner replenishment is performed, and then change at least one of the charging voltage (first voltage) and the developing voltage (second voltage) to decrease the potential difference Vback before the next toner replenishment is performed. As a result, even if the toner consumption rate increases when the number of printed sheets increases to a certain extent after toner replenishment compared to immediately after toner replenishment, toner replenishment notification can be performed at an appropriate timing.

[0183] Second Modification

[0184] In the first embodiment, when toner replenishment increases the charge amount of the toner on the developing roller 4, the toner consumption amount in the halftone image decreases, but the toner consumption amount in the text image and the solid image hardly changes. In the second embodiment, when the potential difference Vback increases when toner replenishment is performed, the toner consumption amount in the halftone image decreases, but the toner consumption amount in the text image or the solid image hardly changes.

[0185] This is because, due to the characteristics of electrophotography, halftone images are more likely to be affected by changes in the toner charge amount and potential difference Vback than solid images. The reason why the toner consumption of halftone images decreases when the potential difference Vback increases is the same as explained in the second embodiment.

[0186] You can refer to Figure 14A The reason why the toner consumption of the halftone image tends to decrease as the charge amount of the toner on the developing roller 4 increases is explained as follows. Figure 14AIn the graph, the horizontal axis represents the average potential on the photosensitive drum 1, and the vertical axis represents image density. In the horizontal axis direction, the right side indicates the post-exposure potential VL, and the left side indicates the pre-exposure potential VD. 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 where 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).

[0187] In the surface area on the photosensitive drum 1 corresponding to the halftone image, the area of ​​the post-exposure potential VL and the area of ​​the pre-exposure potential VD are finely mixed. Figure 14A As shown in the figure, in the surface area 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 area on the photosensitive drum 1 corresponding to the solid image (pure black area) is uniformly at the post-exposure potential VL, and the area on the photosensitive drum 1 corresponding to the white background portion (pure white area) is uniformly at the pre-exposure potential VD.

[0188] Increasing Vback causes the average potential on the photosensitive drum 1 to fluctuate. In a solid black area, 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 a halftone area, when the average potential of the photosensitive drum 1 fluctuates within the same fluctuation range ΔV, the fluctuation range ΔHT of the image density increases. This is because, in the solid black area, toner is developed in multiple overlapping layers, while in the halftone area, toner is developed in a single layer and the coverage of the recording material is also low. Therefore, the reduced amount of toner to be developed significantly affects the image density.

[0189] In any case, in the first embodiment or the second embodiment, when the charge amount of the colorant on the developing roller 4 increases or when the potential difference Vback increases, the colorant consumption in the halftone image may decrease, while the colorant consumption in the text image or the solid image may hardly change.

[0190] In this modified example, to address such situations, the value of coefficient k used in calculating toner consumption is changed based on the area occupied by the halftone area in an image formed by a single image forming operation. In this embodiment, the value of coefficient k is changed so that the larger the area of ​​the halftone area, the smaller the value of coefficient k. For example, the area of ​​the halftone area can be obtained by counting pixels with a density range of 10% to 90% in a raster image obtained through image processing of the image data.

[0191] Figure 14BThe figure shows an example of a determination flow for determining the value of the coefficient k in this modification. The area of ​​the halftone region is defined as S, and the preset threshold is defined as S A 、S B and S C . S A B C , and for example, S A The area S corresponds to about 15% of the A4-sized recording material P. B corresponds to about 30% of the area, and S C This corresponds to approximately 50% of the area.

[0192] The value of coefficient k before the Nth toner replenishment is defined as k n-1 , and the value of coefficient k after the Nth toner replenishment is defined as k n In this modification, when the area S of the halftone region of the image to be printed is equal to or smaller than S A When (S11 “Yes”), k n is set equal to k n-1 When the area S is greater than S A and equal to or less than S B When (S12 “Yes”), k n is set to k n-1 0.8 times (k n / k n-1 =0.8). When the area S is larger than S B and equal to or less than S C When (S13 “Yes”), k n is set to k n-1 0.65 times (k n / k n-1 =0.65). When the area S is equal to or greater than S c When (S13 “No”), k n is set to k n-1 0.5 times (k n / k n-1 =0.5).

[0193] The above-described determination process can also be performed for each image data sheet that is the target of the image forming operation. That is, in continuous printing, the area S of the halftone area in the first image may be different from the area S of the halftone area in the second image. In this case, the value k of the coefficient k used in calculating the toner consumption for the first image may be different from the area S of the halftone area in the second image. n The value k of the coefficient k used in calculating the toner consumption for the second image n It can be different.

[0194] ​​ 15A to 15D An example of the remaining toner amount and the transition of the remaining toner amount indication in the present modification is illustrated.

[0195] Figure 15A The figure shows the transition of the remaining toner amount when continuously printing an image of a large area S having a halftone area such as a full-surface halftone (S13 "No"). When the Nth toner replenishment is performed, the charge amount of the toner on the developing roller 4 increases, and as a result, the toner consumption speed becomes slower than before the toner replenishment. Figure 15B The diagram shows Figure 15A The remaining toner amount indication on the remaining amount display unit 400 is changed under the same conditions as in FIG. Figure 15A and Figure 15B In the example, since a large area S of an image with halftone regions is printed, the value of the coefficient k is k n is set to k n-1 As a result, the value k of the coefficient k is used after toner replenishment. n The calculated rate of decrease of the remaining toner amount (gradient DDn) is the value k of the coefficient k used before toner replenishment. n-1 Half of the rate (gradient DD) at which the calculated remaining toner amount decreases.

[0196] By executing the above-described control, the remaining toner amount calculated based on the dot count value C becomes equal to or less than Qout (0%) at substantially the same timing as the number of printed sheets Pe at which the actual remaining toner amount Q becomes equal to or less than Qout. Therefore, even in the case of an image including a large number of halftone images that are easily affected by the toner charge amount, a toner replenishment notification can be executed at appropriate timing.

[0197] Figure 15C The figure shows the transition of the remaining toner amount when continuously printing an image including only text without halftone areas. When the Nth toner replenishment is performed, the charge amount of the toner on the developing roller 4 increases, but the toner consumption speed has hardly changed since before the toner replenishment. Figure 15D The diagram shows Figure 15C The remaining toner amount indication on the remaining amount display unit 400 is changed under the same conditions as in FIG. Figure 15C and Figure 15D In the example, since an image not including a halftone area (S=0) is printed, the value of the coefficient k is n is set equal to k n-1 As a result, the value of coefficient k is used after toner replenishment. n The calculated rate of decrease of the remaining toner amount (inclination DA) is equal to the value k of the usage coefficient k before toner replenishment. n-1 The rate at which the remaining toner amount decreases (inclination DA) is calculated.

[0198] By executing the above-described control, the remaining toner amount calculated based on the dot count value C becomes equal to or less than Qout (0%) at substantially the same timing as the number of printed sheets Pf at which the actual remaining toner amount Q becomes equal to or less than Qout. Therefore, even when printing an image that is hardly affected by the amount of toner charge (excluding halftone images), a toner replenishment notification can be executed at appropriate timing.

[0199] In the above-described embodiments and modifications, there are cases where the rate of change of the remaining toner amount indication for each printed sheet before toner replenishment is different from the rate of change of the remaining toner amount indication for each printed sheet before toner replenishment (e.g., Figure 9B In order to obtain the rate of change of the remaining toner amount indication (the inclination Dn of the graph), for example, monitoring 7A to 7C The remaining amount display panel 401 or Figure 8 When obtaining the rate of change of the remaining toner amount indication, it is not necessary to continuously print images from 100% to 0% of the remaining toner amount. For example, it is possible to check whether the change of the remaining toner amount indication in the case of printing about 100 images is different before and after toner replenishment. In addition, it is possible to check until 7A to 7C Whether the number of printed sheets until the indication on the remaining amount display panel 401 changes by one level is different before and after toner replenishment.

[0200] In the above description, it has been assumed that the toner present in the developing container 8 before toner replenishment (in-container toner) and the toner replenished into the developing container 8 by toner replenishment (replenished toner) are the same toner in their new state. Without being limited to this, the present technology can also be applied to a case where the in-container toner and the replenished toner are different toners. Different toners means that at least one of the toner properties (e.g., particle size, viscoelasticity, shape, hardness, fluidity, charging performance, material, etc.), additives (material, size, number of additions, strength of addition), and manufacturing methods (suspension polymerization, pulverization, dissolution suspension, and emulsion aggregation) is different.

[0201] When the toner in the container differs from the type of toner being replenished, the mixture of multiple types of toner in the developing container 8 may cause image defects. In this case, as a method of restoring the image defects, fresh toner can be replenished. The user can attempt restoration by replenishing fresh toner, or a maintenance engineer can replenish fresh toner. Furthermore, as in the second embodiment, restoration can be attempted by changing the latent image settings (settings for the charging voltage and the developing voltage).

[0202] To summarize the situations discussed so far, there may be cases where the toner in the container is the same as the toner being replenished, cases where the toner in the container is of a different type than the toner being replenished, and cases where the toner in the container is a mixture of multiple types of toners and a toner of a different type than one or all of the multiple types of toners is replenished. Furthermore, there may be cases where the user or a service engineer simply performs toner replenishment, and cases where the latent image setting is changed after toner replenishment by detecting a replenishment operation, a memory tag, and manual settings by the user or a service engineer.

[0203] In any of the above cases, the present technology can be applied and the same advantages as those of the above embodiments can be obtained. That is, by changing the value of the coefficient k used to calculate the toner consumption based on the dot count value when performing toner replenishment, the toner consumption calculation accuracy can be enhanced.

[0204] In addition, in the above-mentioned embodiment, an example of changing the coefficient k according to the change in the toner consumption after the toner replenishment has been described, but it can also be considered that the image forming conditions are changed so that the toner consumption does not change before the toner replenishment and after the toner replenishment. Examples of changes in image forming conditions include correcting the γ curve (tone curve), adjusting the line width / dot size, and changing the latent image setting. Correction of the γ curve refers to correcting the relationship between the halftone density of the output data and the halftone density of the input image in the image processing for creating data for driving the exposure unit 10 based on image data input from the outside. Adjustment of the line width / dot size refers to changing the line width of the fine line pattern constituting the halftone and the size of each dot of the dot pattern. Changing the latent image setting 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, and the development potential by adjusting the charging voltage, the development voltage, the laser light amount, etc.

[0205] By changing image formation conditions, it is possible to suppress changes in image density and toner consumption for the same image data before and after toner replenishment. However, it can be difficult to adjust image density and toner consumption so that they do not change at all. According to this technology, even if it is difficult to cope with these changes by changing image formation conditions, it is possible to improve the accuracy of calculating toner consumption and remaining toner amount, provide the user with accurate remaining toner amount information, and notify the user of toner replenishment at an appropriate time. Note that this technology can be used in conjunction with a technology that changes image formation conditions to suppress changes in image density before and after toner replenishment.

[0206] In the above embodiment, a monochrome printer is described as an example, but the present technology can also be applied to a color printer that forms a color image using multiple colors of toner. In the color printer, the toner consumption and the remaining toner amount are calculated for each of the multiple colors of toner.

[0207] In the above embodiment, a direct transfer type image forming apparatus has been described in which a toner image formed on the photosensitive drum 1 (photosensitive member) is directly transferred to a recording material P serving as a transfer target. However, the present technology is also applicable to an intermediate transfer type image forming apparatus. In the intermediate transfer type, a toner image formed on the photosensitive drum 1 (photosensitive member) is primarily transferred to an intermediate transfer member serving as a transfer target, and then the toner image is secondarily transferred from the intermediate transfer member to the recording material P.

[0208] In the above embodiment, a configuration is exemplified in which toner replenishment is performed in a state in which the toner pack 40 (replenishment container) is attached to the attachment portion 57. Without being limited thereto, the present technology can be applied to an image forming apparatus having, for example, a configuration in which toner for replenishment is poured from a replenishment container not attached to the apparatus main body through a replenishment port exposed to the outside of the apparatus main body.

[0209] Other embodiments

[0210] The embodiment(s) of the present invention may also be implemented by a computer of a system or device that reads and executes computer-executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be more fully referred to as a "non-transitory computer-readable storage medium") to perform the functions of one or more of the above-described embodiment(s) and / or includes one or more circuits (e.g., application-specific integrated circuits (ASICs)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by a computer of the system or device, for example, by reading and executing computer-executable instructions from a storage medium to perform the functions of one or more of the above-described embodiment(s) and / or controlling one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may include one or more processors (e.g., a central processing unit (CPU), a microprocessing unit (MPU)), and may include a network of separate computers or separate processors to read and execute computer-executable instructions. The computer-executable instructions may be provided to the computer, for example, from a network or storage medium. The storage medium may include, for example, a hard disk, a random access memory (RAM), a read-only memory (ROM), a storage device of a distributed computing system, an optical disk (such as a compact disk (CD), a digital versatile disk (DVD), or a Blu-ray disk (BD)). TM ), one or more of flash memory devices, memory cards, etc.

[0211] Other embodiments

[0212] The embodiments of the present invention can also be implemented by the following method, that is, software (including computer program products of computer programs / instructions) that perform the functions of the above-mentioned embodiments is provided to a system or device through a network or various storage media, and a computer (central processing unit (CPU), microprocessing unit (MPU)) of the system or device reads and executes the computer program / instructions.

[0213] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. An image forming apparatus, comprising: photosensitive member; a toner storage portion configured to store toner; a developing member configured to carry the toner stored in the toner storage portion, supply the toner to the photosensitive member, and develop the latent image on the photosensitive member into a toner image; an attachment portion to which a replenishing container containing toner is attached, the attachment portion being configured to allow replenishment of toner from the replenishing container into the toner storage portion in a state where at least a portion of the replenishing container is outside the image forming apparatus; as well as A control unit is configured to calculate a toner consumption amount by multiplying a count value related to the number of pixels constituting the toner image by a coefficient, the control unit being configured to change a value of the coefficient when the toner replenishment is performed.

2. The image forming apparatus according to claim 1, wherein The control unit is configured to set a value of the coefficient after the toner replenishment is performed to a value smaller than a value of the coefficient before the toner replenishment is performed.

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

4. The image forming apparatus according to claim 2, wherein: The control unit is configured to decrease a value of the coefficient each time the toner replenishment is performed.

5. The image forming apparatus according to claim 1, wherein In a case where an image forming operation is repeatedly performed based on the same image data, the control unit is configured to change the value of the coefficient when the colorant replenishment is performed so that a result of calculating the amount of colorant consumed in the image forming operation after the colorant replenishment is performed is less than a result of calculating the amount of colorant consumed in the image forming operation before the colorant replenishment is performed.

6. The image forming apparatus according to claim 1, wherein In a case where the value of the coefficient is a first value before a current colorant replenishment is performed, the control unit is configured to change the value of the coefficient to a second value smaller than the first value after the current colorant replenishment is performed, and then change the value of the coefficient to a third value larger than the second value before a next colorant replenishment is performed.

7. The image forming apparatus according to claim 1, wherein The control unit is configured to set a value of the coefficient after the toner replenishment is performed to a value greater than a value of the coefficient before the toner replenishment is performed.

8. The image forming apparatus according to claim 1 , further comprising: charging member; a first voltage applying unit configured to apply a first voltage for charging the surface of the photosensitive member to the charging member; as well as a second voltage applying unit configured to apply a second voltage for developing the latent image to the developing member; Here, the control unit is configured to change at least one of the first voltage and the second voltage when the toner replenishment is performed.

9. The image forming apparatus according to claim 8, wherein When the surface potential of the photosensitive member after being charged by the charging member with the first voltage applied thereto is a first potential, and the potential of the developing member with the second voltage applied thereto is a second potential, the control unit is configured to change at least one of the first voltage and the second voltage so that the potential difference between the first potential and the second potential increases when the colorant replenishment is performed.

10. The image forming apparatus according to claim 9, wherein The control unit is configured to change at least one of the first voltage and the second voltage so that the potential difference increases after current toner replenishment is performed, and then change at least one of the first voltage and the second voltage so that the potential difference decreases before next toner replenishment is performed.

11. The image forming apparatus according to claim 1, wherein The control unit is configured to change a value of the coefficient to be used in calculating a toner consumption amount consumed in the image forming operation according to a size of a halftone area of ​​an image formed by the image forming operation after the toner replenishment is performed.

12. The image forming apparatus according to claim 1, further comprising: a transfer unit configured to transfer the toner image from the photosensitive member to a transfer object in a transfer portion, wherein the toner that has not been transferred to the transfer object in the transfer portion is collected in the toner storage portion by the developing member.

13. The image forming apparatus according to any one of claims 1 to 12, wherein: The control unit is configured to calculate a remaining toner amount in the toner storage portion based on the calculated toner consumption amount, and In a case where the remaining toner amount is equal to or smaller than a predetermined threshold, the control unit is configured to notify a user to prompt execution of the toner replenishment.

14. The image forming apparatus according to any one of claims 1 to 12, wherein: The control unit is configured to cause a display unit to display remaining amount information related to a remaining toner amount in the toner storage portion based on the toner consumption amount calculated using the count value and the coefficient.

15. The image forming apparatus according to claim 14, wherein The display unit is an operation panel included in the image forming apparatus, and The remaining amount information is displayed by displaying a screen on the operation panel.

16. The image forming apparatus according to claim 14, wherein The display unit includes a plurality of lamps provided on an outer surface of the image forming device, and The remaining amount information is displayed by turning on / off the plurality of lamps or by a lighting pattern of the plurality of lamps.

17. The image forming apparatus according to any one of claims 1 to 12, further comprising: a detection unit configured to detect attachment / detachment of the replenishing container to the attachment portion, Here, the control unit is configured to change a value of the coefficient based on detection of attachment / detachment of the replenishing container by the detection unit.

18. The image forming apparatus according to any one of claims 1 to 12, further comprising: an operation unit configured to receive an operation from a user, Here, the control unit is configured to change the value of the coefficient based on an input to the operation unit, the input indicating that the toner replenishment using the replenishment container has been completed.

19. The image forming apparatus according to any one of claims 1 to 12, further comprising: an exposure unit configured to expose the photosensitive member, wherein the control unit is configured to develop the image data into a raster image and drive the exposure unit based on the raster image so that the latent image is formed on the photosensitive member, and The count value is the number of dots constituting the raster image.

20. The image forming apparatus according to any one of claims 1 to 12, further comprising: an exposure unit including a light source and configured to expose the photosensitive member using light emitted from the light source; The count value is the accumulated light emission time of the light source.

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