Determination method and recovery method

Abstract

To provide a determination method with which it is possible to determine whether a plurality of types of toner are mixed, and a recovery method with which it is possible to recover from an image defect caused by the mixing of the plurality of types of toner.SOLUTION: A determination method includes: an output step of, by using an image forming apparatus, outputting, to a recording material, a pattern image including a first area in which a halftone image is formed and a second area in which a halftone image is formed comprising dots with a smaller average dot size than the first area; a comparison step of comparing the density of the first area and the density of the second area; and a determination step of determining that a plurality of types of toner are mixed in a toner storage unit when the density of the first area is visually recognized to be higher than the density of the second area in the comparison step.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a method for determining whether or not a plurality of types of toner are mixed in a toner container in an image forming apparatus, and a recovery method for recovering from image defects in an image forming apparatus. [Background technology]

[0002] In image forming devices, methods for replenishing developer (toner) include a cartridge method and an external replenishing method. The cartridge method uses a process cartridge or toner cartridge that is detachable from the main body of the image forming device, and when the amount of developer remaining in the cartridge becomes low, it is replaced with a new cartridge. In the external replenishing method, when the amount of developer remaining in the toner storage unit of the image forming device becomes low, developer is replenished from the outside of the image forming device using a replenishing container that stores developer to the toner storage unit. Patent Document 1 describes a configuration in which toner is replenished from the outside of the image forming device using a toner pack as a replenishing container. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-154302 Summary of the Invention [Problem to be solved by the invention]

[0004] When the toner already stored in the toner storage unit of an image forming apparatus is different from the toner newly replenished from a supply container such as a toner pack or toner cartridge, the mixture of multiple types of toner in the toner storage unit can cause image defects. When an image defect occurs, there is a need for a method for determining whether the image defect is caused by the mixture of multiple types of toner. There is also a need for a recovery method that can appropriately recover from the image defect when the image defect occurs due to the mixture of multiple types of toner.

[0005] Therefore, an object of the present invention is to provide a determination method capable of determining whether multiple types of toner are mixed, and a recovery method capable of recovering image defects caused by the mixing of multiple types of toner. [Means for solving the problem]

[0006] One aspect of the present invention is a method for determining whether multiple types of toner are mixed in a toner storage unit of an image forming device that can replenish toner using a replenishment container, the method comprising: an output step of using the image forming device to output onto a recording material a pattern image including a first region in which a halftone image is formed and a second region in which a halftone image consisting of dots whose average dot size is smaller than that of the first region is formed; a comparison step of comparing the density of the first region with the density of the second region of the pattern image output onto the recording material; and a determination step of determining that multiple types of toner are mixed in the toner storage unit if the density of the first region is visually recognized to be higher than the density of the second region in the comparison step under conditions of an illuminance of 30 lux or more.

[0007] Another aspect of the present invention is a method for determining whether multiple types of toner are mixed in a toner storage unit of an image forming device that can replenish toner in the toner storage unit using a replenishment container, the method comprising: an output step of using the image forming device to output onto a recording material a pattern image including a first region in which a halftone image is formed and a second region in which a halftone image consisting of dots whose average dot size is smaller than that of the first region is formed; a comparison step of comparing the density of the first region with the density of the second region of the pattern image output onto the recording material; and a determination step of determining that multiple types of toner are mixed in the toner storage unit if, in the comparison step, the density of the first region is higher than the density of the second region and the difference between the density of the first region and the density of the second region satisfies a predetermined condition.

[0008] Another aspect of the present invention is a method for determining whether multiple types of toner are mixed in a toner storage section of an image forming device that can replenish toner in the toner storage section using a supply container, the method comprising: a first output step for using the image forming device to output a first pattern image onto a first recording material, the first pattern image including a boundary line indicating the boundary of a predetermined area in the main scanning direction during image formation; a first confirmation step for confirming whether there is an image other than the first pattern image within the predetermined area of ​​the first recording material; and a determination step for determining whether multiple types of toner are mixed in the toner storage section based on the results of the first confirmation step.

[0009] Another aspect of the present invention is a recovery method for recovering from image defects in an image forming device that can replenish toner to a toner storage section within the image forming device using a replenishment container, the recovery method including: an output step of using the image forming device to output onto a recording material a pattern image including a first region in which a halftone image is formed and a second region in which a halftone image consisting of dots whose average dot size is smaller than that of the first region is formed; a comparison step of comparing the density of the first region with the density of the second region of the pattern image output onto the recording material; and a replenishment step of replenishing toner to the toner storage section, wherein the replenishment step is executed if, in the comparison step, it is possible to visually determine that the density of the first region is higher than the density of the second region under conditions of illuminance of 30 lux or more.

[0010] Another aspect of the present invention is a recovery method for recovering from image defects in an image forming device that can replenish toner in a toner storage section within the image forming device using a replenishment container, the recovery method including: an output step of using the image forming device to output onto a recording material a pattern image including a first region in which a halftone image is formed and a second region in which a halftone image consisting of dots whose average dot size is smaller than that of the first region is formed; a comparison step of comparing the density of the first region with the density of the second region of the pattern image output onto the recording material; and a replenishment step of replenishing toner in the toner storage section, wherein the replenishment step is executed if, in the comparison step, the density of the first region is higher than the density of the second region and the difference between the density of the first region and the density of the second region satisfies a predetermined condition.

[0011] Another aspect of the present invention is a recovery method for recovering from image defects in an image forming device that is capable of replenishing toner to a toner storage section within the image forming device using a replenishing container, the recovery method including: a first output step using the image forming device to output onto a first recording material a first pattern image including a boundary line indicating the boundary of a predetermined area in the main scanning direction during image formation; a first confirmation step to confirm whether or not there is an image other than the first pattern image within the predetermined area of ​​the first recording material; and a replenishing step to replenishing toner to the toner storage section, wherein the replenishing step is executed if there is an image other than the first pattern image within the predetermined area in the first confirmation step. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a determination method capable of determining whether multiple types of toner are mixed, and a recovery method capable of recovering image defects caused by the mixing of multiple types of toner. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic diagram of an image forming apparatus according to a first embodiment. [Figure 2]2A and 2B are a perspective view and a front view of a process unit and a toner pack according to the first embodiment. [Figure 3] 2A and 2B are cross-sectional views of a process unit according to the first embodiment. [Figure 4] FIG. 2 is an explanatory diagram of a toner pack according to the first embodiment. [Figure 5] FIG. 2A is a diagram showing a toner pack according to the first embodiment, FIG. 2B is a diagram showing a first modified example of the toner pack, and FIG. 2C is a diagram showing a second modified example of the toner pack. [Figure 6] FIG. 2 is a block diagram showing a control system of the image forming apparatus according to the first embodiment. [Figure 7] 3 shows a determination pattern according to the first embodiment. [Figure 8] 5A and 5B are explanatory diagrams of the dot structure in each region of the determination pattern according to the first embodiment. [Figure 9] 10 is a modified example of a determination pattern according to the first embodiment. [Figure 10] 3 is a flowchart of a determination method according to the first embodiment. [Figure 11] 10 shows examples of determination pattern states and determination results according to the first embodiment. [Figure 12] 1A and 1B are conceptual diagrams showing toner charge distribution when different types of toner are mixed (a) and not mixed (b). [Figure 13] 10 shows a determination pattern according to the second embodiment. [Figure 14] 10 is a flowchart of a determination method according to a second embodiment. [Figure 15] 10A and 10B show examples of image defects and judgment results when a judgment pattern is output according to the second embodiment. [Figure 16] 10 is a modified example of a determination pattern according to the second embodiment. [Figure 17] 10 is a flowchart of a determination method according to a third embodiment. [Figure 18] 10 is a flowchart of a determination method according to a modified example of the third embodiment. [Figure 19] 10 is a flowchart of a recovery method according to a fourth embodiment. [Figure 20] 10 is a flowchart of a recovery method according to a modified example of the fourth embodiment. [Figure 21]10A and 10B are flowcharts of a recovery method according to a modified example of the fourth embodiment. [Figure 22] 10 is a flowchart of a recovery method according to a modified example of the fourth embodiment. [Figure 23] 10 is a flowchart of a recovery method according to a fifth embodiment. [Figure 24] 13 is a flowchart of a recovery method according to a modified example of the fifth embodiment. [Figure 25] 13 is a flowchart of a recovery method according to a modified example of the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0015] Example 1 A first embodiment will be described. FIG. 1 is a schematic diagram showing a cross section of an image forming apparatus 100 according to the first embodiment. The image forming apparatus 100 is an electrophotographic monochrome laser beam printer. Based on image information received from, for example, an external device, the image forming apparatus 100 forms an image on an A4-sized recording material P using toner as a developer while conveying the recording material P in a longitudinal direction. A variety of sheet materials of different sizes and materials can be used as the recording material P (recording medium), including paper such as plain paper and cardboard, surface-treated sheet materials such as coated paper, specially shaped sheet materials such as envelopes and index paper, plastic film, and cloth. Longitudinal feeding refers to conveying the recording material P in a direction in which the long side of the recording material P is parallel to the conveyance direction of the recording material P (long side feeding).

[0016] As shown in FIG. 1, the image forming apparatus 100 includes a process unit 9 and an apparatus main body M that houses the process unit 9. The process unit 9 includes a photosensitive drum 1 and a plurality of process sections arranged around the photosensitive drum 1. In this embodiment, the plurality of process sections are a charging roller 2, a developing device 20, a static eliminator 11, and a brush member 12. The image forming apparatus 100 also includes a mounting section 57 and a locking mechanism 57L. The locking mechanism 57L will be described in Example 4.

[0017] In this embodiment, the process unit 9 is configured to be detachable from the apparatus main body M. However, the present invention is not limited to this, and the process unit 9 may be configured to be non-detachable from the apparatus main body M. Furthermore, only a part of the process unit 9 (for example, the developing device 20 or the developing container 8) may be configured to be detachable from the apparatus main body M.

[0018] The apparatus main body M also has a scanner unit 10 as an exposure device and a transfer roller 13 as a transfer member. The transfer roller 13 abuts against the surface 1a of the photosensitive drum 1, and forms a transfer nip N1 as a transfer portion between the transfer roller 1 and the photosensitive drum 1.

[0019] The photosensitive drum 1 functions as an image carrier that carries an electrostatic latent image and a developer image. The photosensitive drum 1 is a rotatable photosensitive element molded into a cylindrical (drum-shaped) shape. In this embodiment, the photosensitive drum 1 has a photosensitive layer formed of a negatively chargeable organic photosensitive material on a drum-shaped aluminum substrate. More specifically, the photosensitive drum 1 is a rigid body constructed by sequentially applying a resistive layer, an undercoat layer, and a photosensitive layer to the outer surface of an aluminum cylinder with a diameter of 24 mm using a dip coating method. The photosensitive layer includes a charge generation layer and a charge transport layer. The charge transport layer has a film thickness of, for example, 22 μm. The photosensitive drum 1 is driven by a drive motor to rotate around a rotation axis CP at a predetermined peripheral speed in the direction indicated by arrow R. The peripheral speed of the photosensitive drum 1 determines the speed of image formation by the image forming apparatus 100 and is also referred to as the process speed.

[0020] The charging roller 2, which serves as a charging member, contacts the photosensitive drum 1 with a predetermined pressure, forming a charging section N2. In this embodiment, a certain speed difference occurs between the surface speeds of the photosensitive drum 1 and the charging roller 2. A charging voltage, which is a DC voltage, is applied to the charging roller 2 from a charging voltage application section 55a (FIG. 6), and the charging roller 2 uniformly charges the surface 1a of the photosensitive drum 1 to a predetermined potential (referred to as a dark potential VD). The dark potential VD is a negative potential, the same polarity as the toner.

[0021] The charging roller 2 of this embodiment has a core metal with a diameter of 6 mm, a base layer of hydrin rubber, and a surface layer of urethane, and is a roller member with an outer diameter of 12 mm. The resistance of the charging roller 2 is 1×10 6 The hardness is 70 degrees measured by an MD-1 rubber hardness tester. Although a DC voltage is used as the charging voltage in this embodiment, the present invention is not limited to this and may be a voltage in which an AC voltage is superimposed on a DC voltage.

[0022] The scanner unit 10 scans and exposes the surface 1a of the photosensitive drum 1 by irradiating the photosensitive drum 1 with a laser corresponding to image information input from an external device using a polygon mirror. This exposure forms an electrostatic latent image corresponding to the image information on the surface 1a of the photosensitive drum 1. The scanner unit 10 has a semiconductor laser light source, irradiates a laser with a wavelength of 800 nm, and is capable of changing the amount of laser light. Note that the scanner unit 10 is not limited to a laser scanner device, and may be, for example, an LED exposure device having an LED array in which multiple LEDs are arranged along the longitudinal direction of the photosensitive drum 1.

[0023] The developing device 20 has a developing container 8 that forms the frame of the developing device 20, a developing roller 4, and a supply roller 5 that supplies toner to the developing roller 4. The developing container 8 functions as a toner storage section (developer storage section) that stores toner as a developer. Inside the developing container 8, there are formed a storage chamber 8a that is a space for storing toner, and a developing chamber 8b that has the developing roller 4. The developing roller 4 and the supply roller 5 are rotatably supported by the developing container 8. The developing roller 4 is disposed at the opening of the developing container 8 so as to face the photosensitive drum 1. The supply roller 5 abuts against the developing roller 4, and the toner stored in the developing container 8 is applied to the surface of the developing roller 4 by the supply roller 5.

[0024] The developing device 20 of this embodiment uses a contact development method. That is, the toner layer carried on the developing roller 4 comes into contact with the photosensitive drum 1 at a developing portion N3 where the photosensitive drum 1 and the developing roller 4 face each other. In other words, the developing roller 4 as a developing member forms the developing portion N3 between itself and the photosensitive drum 1. A developing voltage, which is a DC voltage, is applied to the developing roller 4 from a developing voltage application unit 55b (FIG. 6). Under the developing voltage, the toner carried on the developing roller 4 is transferred from the developing roller 4 to the surface 1a of the photosensitive drum 1 in accordance with the potential distribution on the surface 1a, thereby developing the electrostatic latent image into a toner image.

[0025] This embodiment employs a reversal development method. Specifically, in the charging process, light is irradiated onto the area of ​​the photosensitive drum 1 where a toner image is to be formed, which has been charged to a dark potential VD. This attenuates the surface potential of the exposed area to a potential (referred to as a light potential VL) whose absolute value is smaller than the dark potential VD. Meanwhile, the development voltage is set to a value between the dark potential VD and the light potential VL. That is, the development voltage has the same polarity as the normal polarity of the toner with respect to the light potential VL and the opposite polarity to the normal polarity of the toner with respect to the dark potential VD. Therefore, in the development station N3, toner from the development roller 4 adheres to the exposed area, which is the area of ​​the light potential VL on the photosensitive drum 1, while toner from the development roller 4 does not adhere to the unexposed area, which is the area of ​​the dark potential VD. This visualizes the potential distribution on the surface 1a of the photosensitive drum 1 with toner, and the electrostatic latent image is developed into a toner image.

[0026] The developing roller 4 in this embodiment is a roller member having a core metal with a diameter of 6 mm, and coated with a base layer of silicone rubber and a surface layer of urethane rubber so that the outer diameter of the entire roller is 15 mm. The resistance value of the developing roller 4 is, for example, 1×10 4 ~1×10 12 The supply roller 5 is a conductive elastic sponge roller with a foam layer formed on the outer periphery of a core metal with a diameter of 6 mm. The resistance value of the supply roller 5 is, for example, 1×10 4 ~1×10 8The hardness of the supply roller 5 in this embodiment is a value measured by the load when a flat plate having a longitudinal width of 50 mm is inserted 1 mm into the surface of the supply roller 5.

[0027] An agitating member 7 is provided inside the developing container 8. The agitating member 7 is driven to rotate by a motor M1 (FIG. 6) serving as a drive source, thereby agitating the toner inside the developing container 8 and sending the toner toward the developing roller 4 and the supply roller 5. The agitating member 7 also circulates, inside the developing container 8, the toner that has been scraped off from the developing roller 4 and not used in development, and plays a role in making the toner inside the developing container 8 uniform.

[0028] A developing blade 6 is disposed at the opening of the developing container 8 in which the developing roller 4 is disposed, and regulates the amount of toner carried by the developing roller 4. The toner supplied to the surface of the developing roller 4 passes through the area facing the developing blade 6 as the developing roller 4 rotates, whereby the toner is uniformly formed into a thin layer and is negatively charged by frictional charging.

[0029] The developing blade 6 is, for example, a 0.1 mm thick metal plate (for example, a stainless steel (SUS) sheet metal). One end (fixed end) of the developing blade 6 is fixed, and the other end (free end) is in contact with the developing roller 4. The developing blade 6 is arranged so that the direction from the fixed end to the free end is inclined toward the upstream side in the rotation direction of the developing roller 4 (counter direction). The developing blade 6 of this embodiment is made by cutting the tip of a SUS sheet metal from the side of the surface that contacts the developing roller 4. The tip portion of the developing blade 6 is bent in the cutting direction by the cutting process.

[0030] The transfer roller 13 functions as a transfer member (transfer unit). The transfer roller 13 has a core metal with a diameter of 5 mm. The transfer roller 13 also has a base layer of ion-conductive sponge formed on the outer periphery of the core metal so that the outer diameter of the entire roller is 12.5 mm. The resistance value of the transfer roller 13 is, for example, 4×10 in an environment at a temperature of 22°C. 7The hardness is 30 degrees, for example, as measured by an Asker C rubber hardness tester manufactured by Kobunshi Keiki Co., Ltd.

[0031] When an image formation command is output to the image forming apparatus 100, a series of operations (image forming operations) is started to form an image on a recording material P based on image information input from an external computer or storage medium connected to the image forming apparatus 100. When the image forming operation is started, the photosensitive drum 1 is driven by a drive source (not shown) and rotated in the direction of arrow R in Fig. 1 at a predetermined process speed. In this embodiment, the process speed of the photosensitive drum 1 is 140 mm / sec.

[0032] The process unit 9 is provided with a static eliminator 11 that eliminates static electricity from the photosensitive drum 1, downstream of the transfer nip N1 and upstream of the charging section N2 in the rotation direction of the photosensitive drum 1. More specifically, the static eliminator 11 as a static eliminator is disposed between the brush member 12 and the charging roller 2 in the rotation direction of the photosensitive drum 1. The static eliminator 11 eliminates the surface potential of the photosensitive drum 1 before it reaches the charging section N2 in order to generate a stable discharge at the charging section N2.

[0033] The charging roller 2 uniformly charges the surface of the rotating photosensitive drum 1 to a dark potential VD. The scanner unit 10 irradiates the photosensitive drum 1 with a laser based on input image information. This forms an electrostatic latent image on the surface 1a of the photosensitive drum 1.

[0034] Meanwhile, a toner layer charged to a predetermined polarity is formed on the surface of the developing roller 4. Then, by applying a developing voltage to the developing roller 4, the electrostatic latent image on the photosensitive drum 1 is developed at the developing unit N3, and a toner image is formed on the photosensitive drum 1. The number of effective pixels of the toner image formed by the above process by the image forming apparatus 100 according to this embodiment is 400 dpi.

[0035] In parallel with the creation of the toner image described above, recording materials P stored in the lower portion of the image forming apparatus 100 are fed one by one. The recording materials P are transported to the transfer nip N1 in synchronization with the timing at which the toner image formed on the photosensitive drum 1 reaches the transfer nip N1. In addition, a DC transfer voltage is applied to the transfer roller 13 from the transfer voltage application unit 55e (FIG. 6) in synchronization with the timing at which the toner image formed on the photosensitive drum 1 reaches the transfer nip N1. As a result, the toner image carried on the photosensitive drum 1 is transferred to the recording material P passing through the transfer nip N1. In this embodiment, the transfer voltage is set to, for example, +1500 V.

[0036] The recording material P onto which the toner image has been transferred is conveyed to the fixing device 14. The fixing device 14 is a thermal fixing device that fixes the image by heating and melting the toner on the recording material P. The fixing device 14 includes, for example, a fixing film 14a, a heat source (heater) such as a ceramic heater that heats the fixing film 14a, and a pressure roller 14b that presses against the fixing film 14a. When the recording material P passes through the nip between the fixing film 14a and the pressure roller 14b, the toner image is heated and pressurized. This melts the toner particles and then fixes them, thereby fixing the toner image to the recording material P. After passing through the fixing device 14, the recording material P is discharged to the outside of the image forming apparatus 100 by a pair of discharge rollers (not shown).

[0037] The image forming apparatus 100 also has an environment detection unit (not shown). The environment detection unit is disposed inside the image forming apparatus 100 and detects the ambient temperature and humidity. Based on the detection results, the voltages applied to the charging roller 2 and the developing roller 4, the scanner unit 10, the transfer roller 13, the fixing device 14, etc. are controlled.

[0038] [Recovery of Transfer Residual Toner] Residual toner remaining on the photosensitive drum 1 without being transferred to the recording material P is removed in the following process. The surface potential of the photosensitive drum 1 after the transfer process is generally lower than the dark potential VD. This is because the surface of the photosensitive drum 1 is affected by the transfer voltage applied to the transfer roller 13 when it passes through the transfer nip N1. In this embodiment, the surface potential of the photosensitive drum 1 after the transfer process is approximately -150V.

[0039] After the transfer process, the surface of the photosensitive drum 1 is neutralized by the neutralization device 11 so that the remaining surface potential is 0V. The residual toner includes a mixture of toner charged to a positive polarity opposite to the normal polarity (negative in this embodiment) and toner charged to a negative polarity but with insufficient charge. The neutralization device 11 neutralizes the photosensitive drum 1 after transfer, and the charging roller 2 generates a uniform discharge, thereby re-charging the residual toner to a negative polarity. The residual toner, negatively charged again at the charging device N2, moves toward the developing device N3 as the photosensitive drum 1 rotates. Furthermore, the surface area of ​​the photosensitive drum 1 that has passed the charging device N2 is exposed to light by the scanner unit 10, and an electrostatic latent image is written onto the surface, with the residual toner still attached to the surface.

[0040] Here, the behavior of the transfer residual toner that has reached the development unit N3 will be explained separately for the exposed area and the non-exposed area of ​​the photosensitive drum 1. The transfer residual toner adhering to the non-exposed area of ​​the photosensitive drum 1 is transferred to the development roller 4 in the development unit 21 due to the potential difference between the development voltage and the dark area potential VD of the non-exposed area of ​​the photosensitive drum 1, and is then collected in the development container 8. This is because the development voltage applied to the development roller 4 is a voltage of positive polarity relative to the dark area potential VD of the non-exposed area. The toner collected in the development container 8 is stirred by the stirring member 7 together with the toner in the development container 8, and is carried by the development roller 4 to be used again in the development process.

[0041] On the other hand, the transfer residual toner adhering to the exposed area of ​​the photosensitive drum 1 does not transfer from the photosensitive drum 1 to the developing roller 4 at the developing portion N3, but remains on the surface 1a of the photosensitive drum 1. This is because the developing voltage applied to the developing roller 4 has a negative polarity relative to the light area potential VL of the exposed area. The transfer residual toner remaining on the surface 1a of the photosensitive drum 1 is carried by the photosensitive drum 1 together with other toner transferred from the developing roller 4 to the exposed area, and moves to the transfer nip N1, where it is transferred to the recording material P.

[0042] In this way, the process unit 9 of this embodiment has a cleaner-less configuration (simultaneous development and cleaning configuration) in which the transfer residual toner is collected and reused in the developing device 20. By making the process unit 9 a cleaner-less configuration, there is no need for installation space for a collection container for collecting the transfer residual toner, etc., making it possible to further reduce the size of the image forming apparatus 100. Furthermore, by reusing the transfer residual toner, it is possible to reduce printing costs.

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

[0044] As shown in FIGS. 2(a) to 3(b), the developer container 8 has a storage chamber 8a that stores the agitator 7. The storage chamber 8a, which serves as a storage space for storing toner, extends over substantially the entire length of the developer container 8 in the longitudinal direction (left-right direction). The inner wall of the storage chamber 8a is formed integrally with a frame that rotatably supports the developing roller 4 and the supply roller 5. The storage chamber 8a stores toner as a developer to be carried by the developing roller 4.

[0045] The developing container 8 also has a first protrusion 37 that protrudes upward from one end of the storage chamber 8a in the longitudinal direction and communicates with the storage chamber 8a, and a second protrusion 38 that protrudes upward from the other end of the storage chamber 8a in the longitudinal direction. An attachment portion 57 to which a toner pack 40 can be attached is provided at the upper end (tip) of the first protrusion 37. A resupply port 32a is formed in the attachment portion 57, through which developer is replenished from the toner pack 40 to the storage chamber 8a. The toner pack 40, which serves as a resupply container, can be attached to the attachment portion 57, with at least a portion of the toner pack 40 exposed to the outside of the image forming apparatus 100.

[0046] The developing container 8 is configured so that toner supplied from the supply port 32a reaches the agitating member 7 by its own weight alone. Here, "by its own weight alone" means that the developing container 8 is configured so that the toner reaches the agitating member 7 by its own weight, without including a rotating or swinging agitating member (conveying member) for transporting the toner between the supply port 32a of the developing container 8 and the agitating member 7. In addition, in the developing container 8, the agitating member 7 is the rotating body closest to the supply port 32a, and is arranged so that the toner in the storage chamber 8a reaches the developing roller 4 or the supply roller 5 by rotating.

[0047] The handle 39 has a knob 39a that can be gripped by a user's fingers. The knob 39a is formed to protrude upward from the top surface of the handle 39. The first protrusion 37 is hollow, and has a supply port 32a formed on its top surface. The supply port 32a is configured to be connectable to a toner pack 40.

[0048] The toner pack 40 is configured to be detachably attached to the mounting portion 57 of the first protrusion 37. The toner pack 40 also includes a bag body, an openable / closable shutter member 41 provided at the opening of the bag body, and a plurality of (three in this embodiment) protrusions 42 formed corresponding to a plurality of (three in this embodiment) grooves 32b formed in the mounting portion 57. When replenishing toner into the developing container 8, the user aligns the toner pack 40 so that the protrusions 42 pass through the grooves 32b of the mounting portion 57, and then connects the toner pack 40 to the mounting portion 57. Then, when the toner pack 40 is rotated 180 degrees in this state, the shutter member 41 of the toner pack 40 abuts against an abutment portion (not shown) of the mounting portion 57, causing the toner pack 40 to rotate relative to the main body of the toner pack 40 and open. This causes toner contained in the toner pack 40 to leak out of the toner pack 40 and enter the hollow first protrusion 37 through the replenishing port 32a. The shutter member 41 may be provided on the supply port 32a side.

[0049] The first protrusion 37 has a slope 37a (FIG. 3(a)) at a position facing the opening of the supply port 32a. The slope 37a is inclined downward toward the storage chamber 8a. Therefore, the toner supplied through the supply port 32a is guided into the storage chamber 8a by the slope 37a. As shown in FIGS. 3(a) and 3(b), the agitator 7 has an agitator shaft 7a extending in the longitudinal direction and blade portions 7b fixed to the agitator shaft 7a and extending radially outward from the agitator shaft 7a. The blade portions 7b are flexible sheets. The agitator 7 rotates around the agitator shaft 7a. The toner supplied through the supply port 32a, which is located upstream of the agitator 7 in the transport direction, is sent toward the developing roller 4 and the supply roller 5 as the agitator 7 rotates.

[0050] In this embodiment, the toner pack 40 is formed from a deformable plastic bag as shown in FIGS. 4 and 5(a), but is not limited thereto. For example, the toner pack may be formed from a substantially cylindrical bottle container 40B as shown in FIG. 5(b), or from a paper container 40C as shown in FIG. 5(c). In either case, the toner pack may be formed from any material and any shape. Furthermore, the toner is preferably discharged from the toner pack by squeezing the toner pack 40 or the paper container 40C with the user's fingers. In the case of the bottle container 40B, the toner is preferably discharged by vibrating the container by tapping, etc. A discharge mechanism may be provided within the bottle container 40B to discharge the toner from the bottle container 40B. Furthermore, the discharge mechanism may be configured to engage with the image forming apparatus 100 and receive driving force from the image forming apparatus 100.

[0051] Furthermore, the shutter member 41 may be omitted in either toner pack, or a sliding shutter member may be used instead of the rotating shutter member 41. The shutter member 41 may be configured to be destroyed when the toner pack is attached to the replenishing port 32a or when the toner pack is rotated while attached, or may have a removable lid structure such as a seal.

[0052] [Control system of image forming apparatus] 6 is a block diagram showing a control system of image forming apparatus 100. Control unit 90, which serves as control means for image forming apparatus 100, includes a CPU 91 as a calculation device, a RAM 92 used as a work area for CPU 91, and a ROM 93 for storing various programs. Control unit 90 also includes an I / O interface 94 as an input / output port connected to external devices, and an A / D conversion unit 95 for converting analog signals into digital signals.

[0053] The input side of the control unit 90 is connected to a remaining toner amount sensor 51 and an installation sensor 53. The remaining toner amount sensor 51 is configured so that a detection signal changes depending on the amount of toner remaining in the developing container 8. The remaining toner amount sensor 51 may be, for example, an optical sensor arranged so that its optical path passes through the inside of the developing container 8 and configured so that its detection signal changes while the optical path is blocked by toner splashed up by the agitating member 7. The installation sensor 53 detects that the toner pack 40 has been installed in the installation portion 57 (supply port 32a) of the developing container 8. For example, the installation sensor 53 may be a pressure-sensitive switch that is provided in the supply port 32a and outputs a detection signal when pressed by the protrusion 42 of the toner pack 40.

[0054] The control unit 90 is also connected to an operation unit 300, the image forming unit 60, and a toner remaining amount panel 400 as a notification unit capable of notifying information related to the amount of remaining toner. The operation unit 300 has a display unit 301 capable of displaying various setting screens, physical keys, etc. The display unit 301 is configured, for example, with a liquid crystal panel. The image forming unit 60 has a motor M1 as a drive source for driving the photosensitive drum 1, developing roller 4, supply roller 5, agitator 7, etc. Note that the photosensitive drum 1, developing roller 4, supply roller 5, and agitator 7 may each be driven by a separate motor.

[0055] The remaining toner amount panel 400 displays information regarding the amount of toner remaining in the developing container 8. The remaining toner amount panel 400 is, for example, one or several lamps, and is controlled so that the lighting state changes stepwise based on the detection signal of the remaining toner amount sensor 51. The user replenishes toner to the developing container 8 using the toner pack 40 based on the lighting state of the lamps on the remaining toner amount panel 400 and / or the screen display of the display unit 301. In addition, the control unit 90 controls the outputs of various high-voltage application circuits (55a to 55e) mounted in the image forming apparatus 100.

[0056] [Latent image settings] Next, the latent image setting of the process unit 9 when printing a determination pattern, which will be described later, will be described. In this embodiment, a charging voltage of −1350 V is applied to the charging roller 2 so that the surface potential (dark area potential VD) of the photosensitive drum 1 becomes −780 V. Then, the scanner unit 10 irradiates the photosensitive drum 1 with a laser based on input image information. As a result, an electrostatic latent image is formed on the uniformly charged surface 1a of the photosensitive drum 1. In this embodiment, the light intensity is set (0.35 μJ / cm in this embodiment) so that the potential (light area potential VL) of the area (solid black area) where the scanner unit 10 has continuously exposed a wide range of light becomes −100 V. 2 Using this light intensity setting, an electrostatic latent image is formed based on image information of a determination pattern, which will be described later.

[0057] On the other hand, the developing voltage in this embodiment is set to −380 V. A voltage of −580 V is applied to the supply roller 5 and the developing blade 6 from a supply voltage application unit 55c and a blade voltage application unit 55d (FIG. 6), respectively.

[0058] [Judgment pattern] The determination pattern used in this embodiment will now be described. Fig. 7 shows the determination pattern TP of this embodiment printed on an A4-sized recording material P. In this embodiment, as will be described later, this determination pattern TP is used to determine whether or not multiple types of toner with different properties are mixed in the developer container 8. Hereinafter, the case where multiple types of toner are mixed in the developer container 8 may be referred to as "different toners mixed," and the case where multiple types of toner are not mixed in the developer container 8 may be referred to as "different toners not mixed."

[0059] The judgment pattern TP is a pattern image (test chart) including multiple areas (A, B) in which halftone images are formed. The judgment pattern TP of this embodiment includes area A consisting of a first dot pattern and area B consisting of a second dot pattern. In other words, the judgment pattern TP as a pattern image used for judgment includes area A as a first area in which a halftone image is formed, and area B as a second area in which a halftone image consisting of dots with an average dot size smaller than that of the first area is formed. The first dot pattern and the second dot pattern differ from each other in the average dot size of the dots that make up the halftone image (the average number of pixels that make up a dot).

[0060] Figure 8 is a schematic diagram showing the dot structure of areas A and B. Each square shown by the dotted grid in Figure 8 represents one pixel at 400 dpi. The colored pixels are pixels where toner is developed to form dots (printed pixels).

[0061] In area A, multiple pixels are connected to form one dot. In this embodiment, the dots in area A are 3x3 pixel squares, and the dot size is 9 pixels. On the other hand, in area B, dots are formed from a single pixel (1x1 pixel). In other words, in this embodiment, the dot size in area B is 1 pixel.

[0062] The halftone images in regions A and B are formed by repeating the pattern shown in Figure 8. It is preferable that the density of the halftone within each region is uniform. The dots are preferably arranged regularly, or randomly, as shown in Figure 8, with the distance between dots as uniform as possible to prevent variations in density.

[0063] In this embodiment, the ratio of the number of printed pixels to the total number of pixels in the pattern (printing rate, coverage rate) is set to 0.136 for region A and 0.124 for region B. This means that the average inter-dot distance is greater in region A than in region B. The printing rate for each region is set so that the visual density of regions A and B is roughly equivalent when no different toners are present in the image forming apparatus 100 of this embodiment. This is to ensure clear visual judgment criteria in the judgment flow described below. However, the above printing rates are not limited to those mentioned above as long as they can be used to judge the presence of different toners. Furthermore, the printing rates for regions A and B are based on the latent image settings described above and may vary depending on the latent image settings of the image forming apparatus used, the laser characteristics of the scanner unit, and other factors.

[0064] In this embodiment, a determination pattern TP is used in which area A and area B are adjacent to each other, as shown in Figure 7. This makes it easier to visually recognize that a density difference has occurred between area A and area B. Furthermore, by using a determination pattern TP in which one area (here, area A) is sandwiched between another area (here, area B), as shown in Figure 7, the density difference becomes easier to visually recognize. Note that the determination pattern TP in which one of areas A and B is sandwiched between the other may be such that the entire periphery of one of areas A and B is surrounded by the other of areas A and B.

[0065] In this embodiment, the pattern is such that an area A having a width of 3 mm in the sub-scanning direction D2 is sandwiched between two areas B having a width of 9 mm in the sub-scanning direction D2. Each of areas A and B is printed with a width of 50 mm in the main scanning direction D1. The rectangular determination pattern TP is printed in the center of the recording material P in the main scanning direction D1 (the center of the area where the process unit 9 can form an image). This is because forming the determination pattern TP in the center in the main scanning direction D1, which is less susceptible to the influence of various variation factors, can improve the stability of the determination.

[0066] (Modification of the judgment pattern) In this embodiment, the pattern is such that area A and area B are adjacent to each other and sandwiched between them for visibility reasons, but this is not limiting as long as it allows for determination based on density differences. For example, area A and area B, which are not adjacent, may be compared as shown in FIG. 9. Alternatively, area A may be printed on the first sheet of recording material P, and area B may be printed on the second sheet of recording material P, and the densities of the first and second sheets may be compared. Alternatively, a sample that serves as a reference density for determination may be prepared in advance, and a determination pattern including only area B may be printed on recording material P and compared with the sample.

[0067] Furthermore, in this embodiment, an example has been described in which each of region A and region B is formed with only one type of dot, but one or both of region A and region B may be formed with multiple types of dots with different dot sizes. For example, region A may be formed with dots with 1 to 2 pixels on a side, and region B may be formed with dots with 3 to 4 pixels on a side. Furthermore, the shape of the dots does not need to be limited to a square as shown in FIG. 8, and other shapes may be used. In such cases, it is sufficient that the average dot size in region A is larger than the average dot size in region B.

[0068] In this embodiment, the printing rate PA of area A is set to a value equal to or greater than the printing rate PB of area B. In other words, the ratio of pixels on which dots are formed to all pixels in area A (first area) is equal to or greater than the ratio of pixels on which dots are formed to all pixels in area B (second area). In this embodiment, PA = 0.136 and PB = 0.124. This is because the distance between dots in area A is large, and the reflective component in areas without scattered toner around the dots is large, making the printed halftone appear brighter (the density is perceived as lighter). Therefore, to ensure that the visual densities of area A and area B are equivalent when different toners are not mixed, it is preferable to set the printing rate PA of area A to a value equal to or slightly greater than the printing rate PB of area B (PA ≥ PB). However, the magnitude relationship between PA and PB is not limited to this, as it can vary depending on the latent image settings and number of effective pixels, as described above.

[0069] Furthermore, in this embodiment, a determination pattern TP is used in which an area A with a large average dot size is sandwiched between areas B with a small average dot size, but a determination pattern in which the relationship between the two is reversed may also be used.

[0070] [Decision flow] The determination flow of this embodiment will be described with reference to Fig. 10. This determination flow will be described assuming that it is performed by a service representative. However, the entity that performs this determination flow is not limited to a service representative, and it may also be performed by a user.

[0071] The service representative first prints the determination pattern TP as the output step (S1). In this embodiment, information about the determination pattern TP is stored in advance in a storage device (ROM 93) within the image forming apparatus 100. When the control unit 90 of the image forming apparatus 100 is instructed to execute the determination mode, it executes an image forming operation based on the information about the determination pattern TP read from the ROM 93, and prints the determination pattern TP on the recording material P. The determination mode may be executed, for example, by displaying an operation screen on a PC screen connected to the image forming apparatus 100 and clicking an execute button on the screen. Alternatively, the determination mode may be executed by operating a button on the operation unit 300 of the image forming apparatus 100.

[0072] Next, in the comparison step (S2), the density DA of region A of the determination pattern TP output on the recording material P is visually compared with the density DB of region B. That is, in the comparison step, the density of the first region of the pattern image output on the recording material P is compared with the density of the second region. Here, in the comparison step of this embodiment, CopyKid paper (manufactured by UPM, A4 size, basis weight 70 g / m) is used as the recording material. 2), but this is not limited to this. Furthermore, in this embodiment, the density comparison of the judgment pattern TP was performed with the angle between the line of sight of the observer (service technician) and the surface of the recording material set perpendicular, and with the distance between the service technician's eyes and the judgment pattern TP on the recording material set at approximately 30 cm. However, these angles and distances are merely examples of common-sense observation conditions, and the present invention is not limited to these conditions. Furthermore, the comparison process is preferably performed in an environment with an illuminance of 500 lux or more, and in this embodiment, it was performed at approximately 800 lux. In fact, if the illuminance is 30 lux or more, it is possible to make a judgment in the judgment process in this embodiment.

[0073] Next, in the determination step (S3), if the visual comparison result is DA>DB (area A is darker), it is determined that different types of toner are mixed in the developer container 8 (S3A), and otherwise it is determined that different types of toner are not mixed (S3B). That is, in the determination step, if the density of the first area is higher than the density of the second area in the comparison step, it is determined that multiple types of toner are mixed in the toner storage section.

[0074] FIG. 11 shows an example of the density relationship of the determination pattern and the determination results. As described above, in this embodiment, a determination pattern TP is used in which region A is located in the center and region A is sandwiched between regions B on both sides. The upper part of FIG. 11 shows a case in which the density DA of region A is higher than the density DB of region B. In this case, it is determined in the determination step S3 that different types of toner are present in the developer container 8 (S3A). The middle part of FIG. 11 shows a case in which the densities DA and DB of regions A and B are approximately equal, and the lower part shows a case in which the density DA of region A is lower than the density DB of region B. In these cases, it is determined in the determination step S3 that different types of toner are not present in the developer container 8 (S3B). The density comparison is not limited to visual inspection and may be performed by measuring the density with a densitometer. Considering the workload, visual inspection is preferable as it allows service personnel and users to make a simple determination. In other words, in this embodiment, if the density of the first region is visually recognized as higher than the density of the second region in the determination step, it is determined that multiple types of toner are mixed in the toner storage unit.

[0075] The following measures can be taken after the determination. If it is determined that different types of toner are mixed, it can be assumed that the cause of the image defect is the mixing of different types of toner, and so, for example, the developer container 8 is replaced. If it is difficult to replace the developer container 8 alone, the process unit 9 may also be replaced. Furthermore, toner may be replenished to change the ratio of the different types of toner mixed in the developer container 8 and thereby recover from the image defect. For example, if the first toner described below is the toner that has been used previously and the second toner is a toner different from the first toner, it is better to replenish the developer container 8 with the first toner to reduce the ratio of the second toner.

[0076] If it is determined that no different types of toner are mixed, it is assumed that the cause of the image defect is not due to the mixing of different types of toner, and other causes continue to be identified. For example, if the cause of the image defect is damage to a component, such as damage to the photosensitive drum 1 for some reason, the photosensitive drum 1 is replaced. If the photosensitive drum 1 cannot be replaced alone, the process unit 9 may be replaced.

[0077] 〔toner〕 An example of two types of toner will be described below to explain why the above determination flow can determine whether different types of toner are mixed in the developer container 8. The two types of toner described below are merely examples, and a similar phenomenon can occur if multiple types of toner with different charging properties are mixed in the developer container 8.

[0078] The first toner is a non-magnetic, single-component polymerized toner whose normal polarity is negative. The average particle size of the first toner is 7 μm. Known methods can be used to manufacture the toner particles, including kneading and grinding methods and wet manufacturing methods. From the viewpoint of uniform particle size and shape controllability, wet manufacturing methods are preferred. Furthermore, wet manufacturing methods that can be used include suspension polymerization, dissolution suspension, emulsion polymerization aggregation, and emulsion aggregation. The suspension polymerization method is used for the first toner. The core particles of the first toner are made of a binder resin whose main component is a styrene-acrylic resin, and have a surface layer containing an organosilicon polymer, and the organosilicon polymer has a structure represented by the following formula (1): R-SiO 3 / 2 Formula (1) (In the formula, R represents a hydrocarbon group having 1 to 6 carbon atoms.)

[0079] Since the surface layer of the first toner has a negative charge polarity, deterioration in charging performance over long-term use is suppressed compared to toners without this surface layer. Furthermore, it is preferable that the surface layer containing the organosilicon polymer and the toner core particles are in contact with each other without any gaps. This suppresses bleeding due to resin components and release agents, etc., inside the toner particles rather than the surface layer, resulting in a toner with excellent storage stability, environmental stability, and development durability. External additives may also be added to the toner particles to ensure fluidity and improve charging properties.

[0080] The second toner, like the first toner, is a non-magnetic, single-component polymerized toner whose normal polarity is negative. The average particle size of the first toner is 7 μm. It uses an inorganic particle-added toner, with inorganic silicon added to the base particles to ensure fluidity and improve charging properties. The second toner uses an emulsion polymerization aggregation method. The core particles of the second toner are made of a binder resin whose main component is styrene-acrylic resin, and do not have a surface layer containing an organosilicon polymer.

[0081] Here, a toner having a surface layer containing an organosilicon polymer is given as an example of the first toner, and a toner not having a surface layer containing an organosilicon polymer is given as an example of the second toner, but the first toner may have a higher charging performance than the second toner. The first toner does not necessarily have to contain an organosilicon polymer, and it does not have to have a core-shell structure in which core particles are covered with a surface layer made of a different material. According to the determination flow of this embodiment, regardless of the specific composition of the toner, it is possible to determine whether multiple types of toner, including a first toner and a second toner having a lower charging performance than the first toner, are mixed in the developer container 8.

[0082] The "charging performance" here refers to the ease with which toner particles are charged, and an index such as the q / d value (charge amount / toner particle diameter) is used. The charging performance of a toner can be defined as the peak q / d value measured when multiple types of toner are not mixed together.

[0083] A specific example of a method for measuring the toner charging performance is as follows. After performing an image forming operation to output one plain (solid white) image using the image forming apparatus 100 and process unit 9 of this embodiment, toner on the developing roller 4 is sampled. The toner sampling position on the developing roller 4 is downstream of the contact position of the developing blade 6 and upstream of the developing unit in the direction of rotation of the developing roller 4. The charge amount (q / d value) of the sampled toner is measured using an E-SpartAnalyzer manufactured by Hosokawa Micron Corporation, and the distribution shown in Figure 12(a) is obtained.

[0084] Figure 12(a) is a simultaneous plot of the distribution of q / d values ​​obtained when the first toner is contained alone in the developing container 8 and the distribution of q / d values ​​obtained when the second toner is contained alone in the developing container 8. When the absolute value of the peak p1 of the q / d value of the first toner is greater than the absolute value of the peak p2 of the q / d value of the second toner, as in Figure 12(a), it can be said that the first toner has higher charging performance than the second toner.

[0085] Methods for increasing the chargeability of the first toner compared to the second toner include forming the surface layer of the first toner with an organosilicon polymer, as well as increasing the amount of external additives that enhance chargeability. Chargeability can also be increased by increasing the amount of charge control agent dispersed in the binder resin of the first toner. Furthermore, the material forming the surface of the first toner may be selected to be on the normal polarity side of the toner (negative polarity in this embodiment) in the triboelectric series relative to the material forming the surface of the second toner. Furthermore, the chargeability of the first toner can be increased compared to the second toner by increasing the amount of external additives that reduce chargeability (to adjust performance other than chargeability) or by forming the core particles of the second toner from a material that is less easily charged.

[0086] Furthermore, as in the modified example described below, even if the toner is manufactured using the same method, the same phenomenon may occur due to differences in charging performance when new toner immediately after being replenished to the developing container 8 is mixed with old toner that has been used repeatedly for image formation. In other words, in this embodiment, the multiple types of toner are not limited to types of toner distinguished by the material of the toner particles, the layer structure of the toner particles, the type and amount of external additives, etc., but may also be types distinguished by changes in the properties of the toner (particularly charging performance) that occur after manufacturing.

[0087] [Image defects and judgment patterns due to the mixing of different toners] The relationship between the image defects and the judgment pattern that occur when the first toner and the second toner are mixed in the developer container will be described below.

[0088] The first toner has a surface layer containing an organosilicon polymer having the structure represented by formula (1), and because the surface layer itself is easily charged to a negative polarity and the surface layer is bonded to the core particle, it has good charging performance and excellent stability. On the other hand, the second toner does not have a surface layer containing an organosilicon polymer, so its charging performance is inferior to that of the first toner.

[0089] 12(a) is a conceptual diagram showing the distribution of the charge amount (q / d value) of the toner particles carried on the developing roller 4 when either the first toner or the second toner is present alone in the developing container 8. In both the case where only the first toner is present in the developing container 8 and the case where only the second toner is present, the distribution of the charge amount has one peak (p1 or p2).

[0090] Figure 12(b) is a conceptual diagram showing the distribution of the charge amount (q / d value) of toner particles carried on the developing roller 4 when the first toner and the second toner are mixed in the developing container 8. When the first toner and the second toner are mixed in the developing container 8, friction between the different toners causes an exchange of charge, increasing the negative charge amount of the first toner and decreasing the charge amount of the second toner. As a result, the toner particles carried on the developing roller 4 are polarized into a group with a high charge amount and a group with a low charge amount, and as shown in Figure 12(b), two peaks p1' and p2' may appear in the distribution of the charge amount of the toner particles.

[0091] Peak p1', which has a larger charge amount, is mainly composed of the first toner, but due to the transfer of charge between the first toner and the second toner, it is shifted to a higher charge side than peak p1 (Figure 12(a)) when the first toner is present alone. Peak p2', which has a smaller charge amount, is mainly composed of the second toner, but due to the transfer of charge between the first toner and the second toner, it is shifted to a lower charge side than peak p2 (Figure 12(a)) when the second toner is present alone. Note that when multiple types of toner with different charging properties are mixed, even if the two peaks p1' and p2' do not appear as clearly as in Figure 12(b), image defects as described below may occur.

[0092] The second toner with a reduced charge amount is transferred as fog toner to the non-exposed area on the photosensitive drum 1 during development, and may also be transferred from the photosensitive drum 1 to the recording material P. As a result, a defective image (fog image) may occur in which a thin layer of toner adheres to an area on the recording material P where an image should not be formed.

[0093] Furthermore, in a cleanerless configuration such as that of this embodiment, the fog toner may contaminate the charging roller 2, leading to a decrease in charging performance, and the dark potential VD may decrease, making the fog image more noticeable.

[0094] Next, the relationship between the presence of different toner types and the judgment pattern will be explained. In area A of the judgment pattern TP, the dot size is large, and almost all of the toner on the surface area of ​​the developing roller 4 corresponding to each dot is developed onto the photosensitive drum 1. For this reason, in area A, there is little difference in the amount of toner developed between when different toner types are mixed and when they are not, and the density of the halftone is less affected by the presence of different toner types.

[0095] On the other hand, in region B of the determination pattern TP, the dot size is small, and only a portion of the toner on the surface area of ​​the developing roller 4 corresponding to each dot is transferred to the photosensitive drum 1. Therefore, when different toners are mixed, and the toner charge distribution is polarized as shown in Figure 12(b), the first toner, which is more negatively charged, is selectively transferred to the photosensitive drum 1, while a portion of the second toner, which is less charged, remains on the developing roller 4. As a result, even if the surface potential (latent image potential) of the photosensitive drum 1, which has been reduced by exposure, is the same, when different toners are mixed, the total amount of toner transferred to the photosensitive drum 1 is less than when no toners are mixed, and the density of the halftone in region B becomes lighter. As a result, when different toners are mixed, the density in region B becomes relatively lighter than that in region A.

[0096] In this way, by using the determination pattern TP including multiple halftone regions with different dot sizes, it is possible to visualize, as halftone density, the change in the charge state of the toner due to the mixture of different toner types in the developer container 8. As a result, when an image defect occurs, it can be determined whether the image defect is due to the mixture of different toner types.

[0097] [Dot size in areas A and B] As described above, in order to visualize the mixture of different toners as a difference in halftone density, it is desirable to set the dot sizes in areas A and B within an appropriate range. As will be explained below, in this embodiment, the halftone image in area A (first area) is made up of dots that are 3x3 pixels or larger in size, and the halftone image in area B (second area) is made up of dots that are 2x2 pixels or smaller in size.

[0098] First, if the dot size in region B is large, the potential (latent image potential) of the surface region corresponding to the dots on the photosensitive drum 1 drops to the bright area potential VL, making it difficult to realize the difference with region A. Therefore, it is advisable to set the dot size so that the latent image potential of the surface region corresponding to the dots on the photosensitive drum 1 becomes a value between the development voltage and the bright area potential VL.

[0099] Specifically, in the image forming apparatus 100 of this embodiment, the latent image potential in an area where one or two consecutive pixels are exposed becomes a value between the development voltage and the bright area potential VL, and when three or more consecutive pixels are exposed, the latent image potential drops to the bright area potential VL. Therefore, it is preferable to set the dot size in area B in the range of 1x1 pixel to 2x2 pixels. Note that this range includes 1x2 pixels, 2x1 pixels, and 2x2 pixels minus any one pixel.

[0100] Increasing the ratio of 1x1 pixel dots in region B makes it easier to detect changes in halftone density when different toners are present, making it easier to determine whether different toners are present. However, in image forming devices with higher resolution than this embodiment, the small size of one pixel makes it difficult to form an appropriate latent image potential. In other words, with 1x1 pixel dots, the latent image potential does not decrease sufficiently upon exposure, and regardless of whether different toners are present, the halftone image is not developed and remains blank, making it impossible to determine whether different toners are present. Therefore, when using an image forming device with higher resolution than this embodiment, it is desirable to set the dot size in region B to the number of pixels that will result in an appropriate latent image potential.

[0101] On the other hand, in the area A, dots of stable density can be formed by lowering the potential (latent image potential) of the surface area corresponding to the dots on the photosensitive drum 1 to the light area potential VL. As described above, in the image forming apparatus 100 of this embodiment, when three or more pixels are exposed consecutively, the latent image potential drops to the light area potential VL. Therefore, it is preferable to form dots of 3 × 3 pixels or more in the area A.

[0102] However, if the dots are made too large, the distance between the dots will also be increased in order to maintain the density relationship with area B, making the dot structure visually noticeable and making it difficult to determine the density. In this example, when the dot size was 5x5 pixels or larger, the dot structure became visually apparent. Therefore, it is preferable to set the dot size in area A to 4x4 pixels or less. To alleviate this visual problem, small dots may be placed between larger dots to increase the average dot size while making the gaps less noticeable. Note that the range of 3x3 pixels to 4x4 pixels includes 4x4 pixels minus any of the 12 outermost pixels.

[0103] In this embodiment, an image forming apparatus 100 with a resolution of 400 dpi was used, but the dot sizes in regions A and B may be changed depending on the resolution of the image forming apparatus. For example, the upper limit of the dot size in region A (4 x 4 pixels) is determined based on the visual coarseness of the dots printed on the recording material P. 4 x 4 pixels at 400 dpi corresponds to approximately 0.01 square inches (0.254 mm square). Therefore, if an image forming apparatus 100 with a resolution of 600 dpi is used, the dot size in region A should be set to 6 x 6 pixels or less, which corresponds to approximately 0.01 square inches (0.254 mm square) at 600 dpi. Meanwhile, the upper and lower limits of the dot size in region B and the lower limit of the dot size in region A are primarily determined in relation to the latent image potential, but these may also be changed depending on the resolution of the image forming apparatus. For example, the dot size of area B may be set to a size equivalent to 1×1 pixel or more and 2×2 pixels at 400 dpi (an area of ​​63.5 μm square or more and 127 μm square or less).

[0104] (Variation) In the above description, we have taken the example of a case where multiple types of toner manufactured by different methods are mixed. However, the same thing can also happen when, for example, new toner is replenished after excessive toner degradation. If there is a large difference in the charging performance of the toner before and after replenishment, image defects (fog images) similar to those observed when the first and second toners are mixed, even though the toner is originally the same, can occur. This situation can also be considered a situation where multiple types of toner are mixed. According to the determination method of this embodiment, even in such a case, it is possible to determine whether the image defects are caused by the mixing of old, degraded toner and new toner.

[0105] Furthermore, although in this embodiment the information on the judgment pattern TP is recorded in a storage device within the image forming apparatus 100, the information on the judgment pattern TP does not necessarily have to be stored in the image forming apparatus 100. For example, an image file of the judgment pattern TP may be sent from an external device such as a PC connected to the image forming apparatus 100 and printed. Furthermore, if a dedicated judgment mode is not set, the judgment pattern TP may be printed manually by sending an image file of the judgment pattern TP to the image forming apparatus 100 in the same way as during normal printing.

[0106] In addition, in this embodiment, the determination is made by comparing the densities of area A and area B, but the comparison is not limited to two areas. For example, area C may be provided as a third area of ​​dot size between area A and area B, and an additional comparison of the densities of area A and area C, or area B and area C, may be made.

[0107] In this embodiment, the comparison step (S3) is described as a process in which the service staff visually compares the halftone densities of areas A and B, but the following method may be used to improve the accuracy of the judgment. As shown in Fig. 11, a judgment chart is prepared in advance that includes three levels of standard images (sample images, reference images) with different magnitude relationships between the halftone densities DA and DB of areas A and B, and the service staff compares the actually output judgment pattern TP to determine which level of standard image it is closest to.

[0108] The density difference between areas A and B measured using the determination pattern TP of this embodiment was actually measured using a densitometer (for example, a spectrodensitometer 500 series manufactured by X-rite, model number 504) and compared with the visibility of the density difference as seen with the naked eye. In this case, when DA>DB, the density difference was almost impossible to visually recognize when the density difference was less than 0.01. Therefore, in this embodiment, if the halftone of area A is darker than the halftone of area B and the density difference is greater than 0.01, it is determined that different toners are mixed in.

[0109] As described above, the density comparison in the determination method of this embodiment is not limited to visual inspection, but may be performed by comparison with a standard image of a previously prepared determination chart, or by density measurement with a densitometer. In other words, it may be determined that multiple types of toner are mixed in the toner storage unit not only when the density difference between the first region and the second region can be visually confirmed, but also when the density of the first region is higher than the density of the second region in the comparison process and the difference between the density of the first region and the density of the second region satisfies a predetermined condition.

[0110] When a judgment chart is used, the predetermined condition is, for example, that the density level in the judgment chart differs by at least one step between the standard image closest to the density of the first region and the standard image closest to the density of the second region.When a densitometer is used, the predetermined condition is, for example, that the difference between the measured values ​​of the density of the first region and the density of the second region measured using the aforementioned X-rite densitometer (spectrodensitometer 500 series, model number: 504) is 0.01 or more.

[0111] Example 2 Next, Example 2 will be described. Example 2 is a modification of the determination pattern of Example 1. Below, elements with the same reference symbols as Example 1 have basically the same configurations and functions as those described in Example 1 unless otherwise specified, and differences from Example 1 will be mainly described. In this example, it will be explained that the determination pattern of Example 1 may not be able to correctly determine whether different types of toner are mixed, and a determination method that can correctly determine whether different types of toner are mixed even in such cases.

[0112] [Judgment pattern] The determination pattern TP of this embodiment will be described with reference to Fig. 13. The determination pattern TP of this embodiment is obtained by adding two reference vertical lines L to the outside of the pattern of embodiment 1. The two reference vertical lines L are examples of boundary lines that indicate the boundaries of a predetermined area in the main scanning direction during image formation.

[0113] In this embodiment, a determination pattern TP is used in which a reference vertical line L is added 60 mm outside the determination pattern TP (FIG. 7) of embodiment 1 in the main scanning direction D1. By using this determination pattern TP, the toner state can be determined using a determination criterion different from that of embodiment 1.

[0114] [Decision flow] The determination flow of this embodiment will be described with reference to Fig. 14. As in the first embodiment, this determination flow will be described on the assumption that it is carried out by a service representative.

[0115] First, in the output step (S11), the service technician prints a test pattern TP on recording material P. Next, in the comparison step (S12), the technician visually compares the density DA of area A of the test pattern TP output on the recording material with the density DB of area B. If the visual comparison shows that DA > DB (area A is darker), the process proceeds to the determination step (S14), where it is determined that different types of toner are mixed in the developer container 8 (S14A). On the other hand, if the result is not DA > DB, the determination is withheld and the process proceeds to the print confirmation step (S13).

[0116] In the print confirmation step (S13), it is confirmed whether there is any printing other than the judgment pattern inside the two reference vertical lines L of the judgment pattern TP output on the recording material P. In this embodiment, printing other than the judgment pattern is, for example, vertical lines as shown in Figure 15. Figure 15 shows an example of judgment in the print confirmation step.

[0117] Next, in the determination step (S14), if there is a vertical line inside the two reference vertical lines L as shown in FIG. 15(a), it is determined that different types of toner are mixed (S14A). That is, in this embodiment, if there is printing other than a pattern image within the predetermined area in the print confirmation step, it is determined that multiple types of toner are mixed in the toner storage unit. If there is a vertical line outside the two reference vertical lines L as shown in FIG. 15(b), or if there is no vertical line, it is determined that different types of toner are not mixed (S14B). Furthermore, in this embodiment, if there are vertical lines both inside and outside the two reference vertical lines L, it is determined that different types of toner are mixed (S14A). The response after the determination is the same as in Example 1.

[0118] The above has been explained using a flowchart, but it is also possible to prepare a table in advance that can compare the judgment results according to the combination of the results of the density comparison process and the print confirmation process, as shown in Table 1, and compare the printed judgment pattern TP to determine which case it applies to.

[0119] [Table 1]

[0120] 〔toner〕 An example of two types of toner will be described below to explain why the two reference vertical lines L added in this embodiment can be used to determine whether different types of toner are mixed in the developing container 8. The two types of toner described below are merely examples, and are not limited to this, as long as the combination of toners has different shapes.

[0121] The first toner is the same as in Example 1. The third toner is a non-magnetic single-component toner with negative charging polarity. The core particles of the third toner are made of a binder resin whose main component is a styrene-acrylic resin, and have an average particle size of 10 μm. This toner is manufactured by mixing raw materials, melting them, cooling them to solidify them, and then pulverizing and surface-treating the powder raw materials while adjusting the temperature in a mechanical pulverizer. The third toner uses an inorganic particle-added toner in which inorganic silicon is externally added to the base particles to ensure fluidity and improve charging properties.

[0122] Due to the manufacturing process, the third toner, which is a pulverized toner, has a larger particle size variation than the first toner, which is a polymerized toner, and the upper limit of the particle size distribution tends to be larger than the average particle size difference. Furthermore, the average circularity of the first toner is about 0.99, while that of the third toner in this embodiment is about 0.92, meaning that the toner shapes are large and distorted. However, even between polymerized toners or pulverized toners, differences in circularity may occur due to differences in manufacturing process, and toner with low circularity is also likely to fuse to the developing blade 6, as described below.

[0123] In this example, the average circularity was used as a simple method for quantitatively expressing the shape of particles, and was calculated as follows: First, the particle shape of the toner particles was measured using a flow particle image analyzer FPIA-2100 manufactured by Toa Medical Electronics Co., Ltd., and the circularity was calculated using the following formula (1): Ci represents the circularity of the ith toner particle.

[0124]

number

[0125] Furthermore, as shown in the following formula (Equation 2), the average circularity is defined as the value obtained by dividing the sum of the circularities of all the measured particles by the total number of particles (m).

[0126]

number

[0127] [Image defects and judgment patterns due to the mixing of different toners] The relationship between the image defects and the judgment pattern that occur when the first toner and the third toner are mixed in the developing container 8 will be described.

[0128] First, we will explain the image defects caused by the third toner. The third toner has a large particle size due to its manufacturing process, and its shape is also distorted due to the manufacturing process. Therefore, when the toner supplied to the developing roller 4 passes through the area facing the developing blade 6, some of the toner may be caught (pressed hard) by the developing blade 6, resulting in fusion. In the areas where this fusion occurs, the developing blade 6 cannot sufficiently charge the toner on the developing roller 4, and a fog image with vertical black streaks may occur, as shown in Figure 15.

[0129] In particular, in a cleanerless configuration such as this embodiment, the vertical black streak-like fog toner may contaminate the charging roller 2, making the vertical black streak-like image defect more noticeable.

[0130] 15 shows continuous vertical black streaks, but there are also cases where image defects appear as discontinuous vertical dotted lines in the sub-scanning direction D2 at a period corresponding to one rotation of the charging roller 2. In the judgment flow described above, the vertical black streaks are regarded as vertical lines that serve as a marker for determining whether different types of toner are mixed in, and judgment is made in the print confirmation process.

[0131] Next, we will explain the characteristics of vertical black streaks that occur when the first toner and the third toner are mixed. Here, the toner mixed with the third toner is referred to as the first toner. However, this is not necessarily limited to this, as long as it is a polymeric toner with a uniform particle size and shape. The first toner has a surface layer containing an organosilicon polymer and, as described in Example 1, has good charging performance and excellent stability. On the other hand, the third toner has an irregular shape due to its manufacturing process, and therefore has even inferior charging performance compared to the second toner in Example 1. When there is such a large difference in charging performance, the first toner is electrostatically selectively developed and consumed when the mixed toner in the developer container 8 is supplied from the supply roller 5 to the developer roller 4. Then, when the remaining amount of the first toner in the developer container 8 becomes low, the third toner begins to be supplied to the developer roller 4 at a high rate.

[0132] In this way, in the case of a toner combination like that of this embodiment, even if different types of toner are mixed in the developer container 8, one of the toners is selectively coated on the developing roller 4. Therefore, the situation in which toners are mixed on the developing roller 4 as shown in Figure 12(b) is temporary, and the presence of different types of toner may not be properly determined using the determination pattern TP of the first embodiment.

[0133] When the third toner starts to be supplied to the developing roller 4, vertical black streaks start to appear as described above. At this time, the vertical black streaks start to appear within the range of the maximum area (image area) in which the developing roller 4 can develop a toner image in the main scanning direction D1. The reason for this is as follows.

[0134] In the image area, toner is consumed as the toner image is developed, but at least in the non-image area at the edges, including the margins, almost no toner is consumed. Therefore, in the image area, as toner is consumed, the toner supplied to the developing roller 4 changes from the first toner to the third toner, but the first toner remains on the developing roller 4 in the non-image area. In other words, image defects due to toner jamming are more likely to occur in the image area than in the non-image area, and can be said to be a phenomenon that occurs when toners are mixed.

[0135] However, vertical black streaks are less likely to occur in non-image areas compared to image areas, but they do not completely disappear. Therefore, in the above-mentioned judgment flow, if vertical black streaks occur both inside and outside the two reference vertical lines L, it is determined that different toners are mixed in. However, the judgment method is not limited to this, and it may also be determined based on the occurrence ratio of vertical black streaks inside and outside the two reference vertical lines L, taking into account the occurrence probability of vertical black streaks. Furthermore, if vertical black streaks occur outside the two reference vertical lines L, it may also be determined that different toners are not mixed in, regardless of whether vertical black streaks exist inside the two reference vertical lines L.

[0136] In this embodiment, the two reference vertical lines L are printed slightly inside the boundary between the non-image area (margin) and the image area. In other words, the predetermined area indicated by the boundary line of the pattern image (reference vertical lines L) is an area that is included within the maximum area in which the image forming device can form an image in the main scanning direction. Therefore, based on the presence or absence of image defects (vertical black streaks) inside the two reference vertical lines L, it is possible to determine whether the cause of the image defects is the mixing of different types of toner.

[0137] In this embodiment, the positions of the two reference vertical lines L are set slightly inside the boundary between the non-image area and the image area, taking into consideration the possibility that a portion of the first toner remaining in the non-image area in the developing container 8 may flow into the inside of the image area. However, the present invention is not limited to this, and the two reference vertical lines L may be formed at the boundary position between the non-image area and the image area, for example.

[0138] Furthermore, in this embodiment, the boundary of the area where the image defect (vertical black stripe) occurs is represented by two reference vertical lines L, but this is not limited to this. For example, as shown in FIG. 16, a pattern may have a judgment area surrounded by a rectangle with two sides at the same positions as the two reference vertical lines L, and the print confirmation process may be performed within the judgment area to make the judgment. Furthermore, the two reference vertical lines L are not necessarily required for the judgment; the service staff may use a ruler to perform the print confirmation process inside the position that marks the boundary. To simplify the judgment process for the service staff, it is preferable to print the reference vertical lines L or a substitute for them within the judgment pattern.

[0139] As described above, according to this embodiment, even when the determination pattern of the first embodiment cannot correctly determine whether different types of toner are mixed, it is possible to more appropriately determine whether different types of toner are mixed.

[0140] Example 3 Next, a description will be given of Example 3. Example 3 is a modification of the judgment flow of Example 2. Hereinafter, elements with the same reference symbols as Example 2 will be considered to have basically the same configurations and functions as those described in Example 2 unless otherwise specified, and differences from Example 2 will be mainly described.

[0141] [Preliminary action] In this embodiment, in order to improve the accuracy of the judgment using the judgment pattern TP, the judgment pattern TP is printed on two sheets of recording material P. Also, in this embodiment, a process of performing a preparatory operation is provided between printing the first and second sheets.

[0142] The reason for performing the preliminary operation in this embodiment will be explained. Since the determination pattern TP in the first embodiment primarily determines the state of the toner in the developer container 8 solely based on the difference in halftone density, it may become difficult to make a determination if the surface potential of the photosensitive drum 1 fluctuates due to secondary factors such as the following. For example, because the image forming apparatus 100 in this embodiment has a cleanerless configuration, some of the fog toner adhering to the non-exposed area of ​​the photosensitive drum 1 adheres to the charging roller 2. Under conditions where a large amount of fog toner is generated, the amount of toner adhering to the charging roller 2 also increases, changing the charging performance and causing the dark potential VD to fluctuate. When the dark potential VD shifts more negatively, the halftone density becomes lighter overall, but this is particularly likely to occur in region B of the determination pattern TP due to the small dot size. Therefore, there is a possibility that a misjudgment may be made that different types of toner are mixed in the developer container 8, even when they are not.

[0143] This phenomenon is likely to occur in a high humidity environment. Particularly in conditions such as first thing in the morning when the image forming apparatus 100 is first used, the charge of the toner in the developing container 8 is attenuated by the influence of moisture in the atmosphere, and a large amount of fog toner is likely to occur. Therefore, in this embodiment, the following preliminary operation is performed to improve the accuracy of the determination.

[0144] The preliminary operation in this embodiment is an operation for cleaning the charging roller 2 to remove the fogging toner while driving the developing roller 4 to rotate, and is made up of a combination of the following two operations.

[0145] The first operation will be described. In the first operation, a voltage of -600V is applied to the charging roller 2 and transfer roller 13, and a voltage of +150V is applied to the developing roller, causing idle rotation (driving each component to rotate without forming an image). At this time, the surface potential of the photosensitive drum 1 is approximately -50V. In this operation, a positive voltage is applied to the developing roller 4, thereby reducing the occurrence of fog toner due to insufficient charging of the charging roller 2. This operation also negatively polarizes the toner adhering to the charging roller 2 due to the friction caused by the difference in peripheral speed between the charging roller 2 and the photosensitive drum 1, and the negatively polarized toner is then ejected onto the photosensitive drum 1 due to the potential difference. The toner ejected onto the photosensitive drum 1 is collected by the developing roller 4 in the developing section.

[0146] In this way, in the first operation, a voltage of the same polarity as the normal polarity of the toner is applied to the charging roller 2, and a voltage of the opposite polarity to the normal polarity of the toner is applied to the developing roller 4, while the charging roller 2 and the photosensitive drum 1 are rotated so that they rub against each other.

[0147] Next, the second operation will be described. In the second operation, a voltage of +150 V is applied to the developing roller 4, causing it to idle, while the voltage applied to the charging roller 2 is turned ON and OFF at regular intervals. In this embodiment, the applied voltage when ON is -900 V, and is repeatedly switched ON and OFF at intervals of 900 ms, which is more than one rotation of the photosensitive drum, to form a surface potential corresponding to one rotation of the photosensitive drum. At this time, the surface potential of the photosensitive drum 1 is approximately -350 V, and the toner adhering to the charging roller 2 is expelled onto the photosensitive drum 1 by turning the voltage application to the charging roller 2 ON and OFF. Furthermore, in this embodiment, the voltage application to the charging roller 2 is turned ON and OFF, but it does not necessarily have to be turned OFF. As long as the voltage is more positive than -350 V, toner of the same polarity as when the voltage is OFF can be expelled onto the photosensitive drum.

[0148] In this way, in the second operation, a voltage of the same polarity as the normal polarity of the toner and a voltage of the opposite polarity to the normal polarity are alternately applied to the charging roller 2, and the photosensitive drum 1 is rotated while a voltage of the opposite polarity to the normal polarity of the toner is applied to the developing roller 4.

[0149] In this embodiment, the preliminary operation, which includes the first and second operations, is performed for approximately 80 seconds. By performing this preliminary operation, even in the morning in a high-humidity environment where the toner charge has decayed, the toner charge is increased, reducing the amount of fog toner and cleaning the charging roller 2 to which the fog toner has adhered. This suppresses fluctuations in the surface potential of the photosensitive drum 1 due to secondary factors, and the half-tone density of region B of the determination pattern TP more appropriately reflects the state of the toner in the developer container 8. This allows for more accurate determination in the comparison process.

[0150] Furthermore, since the vertical lines checked in the print confirmation process in Example 2 are prints that occur due to insufficient charging of the charging roller 2 as described in Example 2, the level of the vertical lines tends to be better after the preliminary operation compared to before the preliminary operation. Indicators of the level of the vertical lines here include the width, number, and density of the vertical lines, and the wider the width, the more number, or the higher the density, the worse the level. Therefore, only the print confirmation process is performed on the first test pattern TP to determine whether or not different types of toner are mixed.

[0151] As a method for executing the preparatory operation, for example, an operation screen for executing the preparatory operation may be displayed on the screen of a PC connected to the image forming apparatus 100, and an execution button may be clicked. Alternatively, the preparatory operation may be executed by operating a button on the screen of the operation unit 300 of the image forming apparatus 100.

[0152] [Decision flow] The determination flow of this embodiment will be described with reference to Fig. 17. As in the first embodiment, this determination flow will be described on the assumption that it is carried out by a service representative.

[0153] First, as a first output step (S21), the service representative causes the image forming apparatus 100 to execute the judgment mode and print a judgment pattern TP similar to that in the second embodiment onto a recording material P. The judgment pattern TP output at this time is set as the first judgment pattern. Here, the method of executing the judgment mode is the same as in the first embodiment. That is, in the first output step, the image forming apparatus 100 outputs onto a first recording material a first pattern image including a boundary line indicating the boundary of a predetermined area in the main scanning direction during image formation.

[0154] Next, in the first print confirmation step (S22, first confirmation step), it is confirmed whether there is a vertical line inside the two reference vertical lines L of the judgment pattern on the first sheet. If there is a vertical line in S22, the process proceeds to the judgment step S27 (different toner mixture judgment step), where it is determined that different toners are mixed (S27A). If there is no vertical line in S22, the process proceeds to the preliminary operation execution step (S23).

[0155] Next, in a preliminary operation execution step (S23), the image forming apparatus 100 is caused to perform a preliminary operation. After the preliminary operation is completed, in a second output step (S24), the image forming apparatus 100 is caused to execute a judgment mode, thereby printing a judgment pattern TP similar to that in the second embodiment again onto the recording material P. The judgment pattern TP output at this time is set as the second judgment pattern. In other words, in the second output step, after the preliminary operation, the image forming apparatus 100 is caused to output onto the second recording material a second pattern image including a first region where a halftone image is formed and a second region where a halftone image consisting of dots with an average dot size smaller than that of the first region is formed.

[0156] Next, in the comparison step (S25), the density DA of region A of the test pattern TP on the second sheet is visually compared with the density DB of region B. If DA>DB (region A is darker), the test pattern TP on the second sheet is judged to contain different toners (S27A). On the other hand, if DA>DB, the test pattern TP on the second sheet is checked to see if a vertical line exists inside the two reference vertical lines L of the test pattern, as in the second embodiment. If no vertical line exists in S26, the test pattern TP on the second sheet is judged to contain different toners (S27B). On the other hand, if a vertical line exists in S26, the test pattern TP on the second sheet is judged to contain different toners (S27A). The process after the judgment may be the same as in the first embodiment.

[0157] The above judgment flow is the same as preparing a table in advance that can compare judgment results according to combinations of the results of the density comparison process and the print comparison process, as shown in Table 2, and then judging by comparing which case in Table 2 the judgment patterns TP of the first and second sheets apply to. Either a method of making a judgment in order according to the flowchart in Fig. 17 or a method of making a judgment according to a judgment table such as Table 2 may be used.

[0158] [Table 2]

[0159] By carrying out the preliminary operation step in the above determination flow, contamination of the charging roller 2 by fog toner can be reduced, and therefore the accuracy of determining the presence of foreign toner based on the density difference of halftones can be improved.

[0160] In the judgment flow of FIG. 17, areas A and B of the judgment pattern TP on the first sheet are not used for judgment. Therefore, the judgment pattern TP on the first sheet may be a pattern on which only the two reference vertical lines L added in the second embodiment are printed. Furthermore, since the purpose of the preliminary operation is to improve the accuracy of density comparison and also to improve vertical black stripes, it is possible to judge the presence of different toner types by performing only the comparison step S25 and without performing the second print confirmation step S26. Therefore, the judgment pattern TP of the first embodiment, which does not have the reference vertical lines L, may be used as the judgment pattern TP on the second sheet.

[0161] As described above, by carrying out the determination flow of this embodiment, it is possible to improve the accuracy of determining whether or not different types of toner are mixed in the developing container 8.

[0162] In this embodiment, the preparatory operation is performed for approximately 80 seconds, but the duration of the preparatory operation may be changed depending on the temperature and humidity detected by the environment detection unit. For example, if the duration of the preparatory operation is lengthened as the humidity increases, the accuracy of the determination can be improved with the minimum time required depending on the environment at the time of determination.

[0163] Furthermore, in this embodiment, the judgment flow is such that the preliminary operation is performed during the period between printing two judgment patterns TP, but the judgment flow of embodiment 1 may also be such that the preliminary operation is performed before printing the judgment pattern TP, thereby improving the judgment accuracy in the judgment method of embodiment 1.

[0164] (Variation) In the third embodiment, the print confirmation process was performed separately for the first and second sheets (S22, S26), and if a vertical line was found inside the reference vertical line L on at least one of the first and second sheets, it was determined that different toners were mixed. However, as mentioned above, the level of the vertical line caused by the mixing of different toners tends to change before and after the preliminary operation process. Therefore, the level of the vertical line in the determination pattern TP for the first and second sheets may be compared, as shown in the determination flow in FIG. 18.

[0165] The first output process S31, the preparatory operation execution process S32, the second output process S33, and the comparison process S34 in this modification are the same as the first output process S21, the preparatory operation execution process S23, the second output process S24, and the comparison process S25 in the second embodiment shown in Fig. 17. On the other hand, in this modification, if there is a vertical line inside the reference vertical line L in the first judgment pattern TP (Yes in S35) and the level of the vertical line in the second judgment pattern TP is improved compared to the first page (Yes in S36), it is determined that a different type of toner is present. If there is no vertical line inside the reference vertical line L in the first judgment pattern TP (No in S35), it is determined that a different type of toner is not present, regardless of the level of the vertical line in the second judgment pattern TP. Also, even if there is a vertical line inside the reference vertical line L in the first judgment pattern TP (S35 Yes), or if the level of the vertical line in the second judgment pattern TP has not improved compared to the first page (S36 No), it is determined that there is no mixing of different toners.

[0166] In this manner, in this embodiment, the presence of different types of toner is determined based on the change in the level of the vertical lines before and after the execution of the preparatory operation step. In other words, if the level of the image other than the pattern image that appears in the specified area when the pattern image is output after the preparatory operation step is improved compared to the image other than the pattern image that appears in the specified area when the pattern image is output before the preparatory operation step, it is determined that multiple types of toner are present in the toner storage unit.

[0167] This makes it possible to more accurately determine whether different types of toner are mixed, based on the mechanism by which vertical lines occur.

[0168] The judgment flow of this modified example is the same as preparing a judgment table like Table 3 below in advance and comparing the judgment patterns TP of the first and second sheets to determine which case applies. A "-" in the table indicates that the judgment result in the right column is applied regardless of whether the item is Yes or No. Either a method of making a judgment in order according to the flowchart in FIG. 18 or a method of making a judgment according to a judgment table like Table 3 may be used.

[0169] [Table 3]

[0170] Example 4 Next, a fourth embodiment will be described. In the fourth embodiment, a series of procedures (recovery flow) for selectively carrying out a process for recovering from an image defect will be described in addition to the determination flow described in the first embodiment. Hereinafter, elements with the same reference numerals as those in the first embodiment will have basically the same configurations and functions as those described in the first embodiment unless otherwise specified, and differences from the first embodiment will be mainly described.

[0171] In this embodiment, the process unit 9 is configured to be detachable from the apparatus main body M, and a service technician can replace the process unit 9. However, the process unit 9 includes the photosensitive drum 1, the charging roller 2, the developing device 20, the static eliminator 11, and the brush member 12, and components unrelated to the cause of image defects may also be replaced as part of the process unit 9. For this reason, it is preferable to keep the replacement of the process unit 9 to a minimum.

[0172] [Recovery flow] A series of flows in this embodiment will be described with reference to Fig. 19. This flow will be described assuming that it will be performed by a service representative. However, the entity that performs this flow is not limited to a service representative, and it may also be performed by a user.

[0173] The service representative first prints the determination pattern TP in the output step (S1). Next, in the comparison step (S2), the service representative visually compares the density DA of area A and the density DB of area B of the determination pattern TP output onto the recording material P. That is, in the comparison step (S2), the density of the first area and the density of the second area of ​​the pattern image output onto the recording material P are compared. Up to this point, the process is the same as in the first embodiment.

[0174] Next, if the comparison result in the comparison step (S2) is DA>DB (area A is darker), the service person mounts a new toner pack 40 in the mounting portion 57 and replenishes toner (R3A) as the recovery step (R3). That is, if it is determined in the first embodiment that different types of toner are mixed in the developing container 8 (S2 Yes in FIG. 10), toner is replenished in this embodiment as the recovery step (R3) (R3A, replenishment step).

[0175] On the other hand, if the comparison result in the comparison step (S2) is not DA>DB (area B is darker or the toners are about the same), the service technician replaces the process unit 9 (R3B). In other words, if it is not determined in Example 1 that different types of toner are mixed in the developer container 8 (S2No in FIG. 10), the process unit 9 is replaced as the recovery step (R3) in this example (R3B, replacement step).

[0176] [Recovery of poor image quality by toner replenishment] In the above flow, the reason why the image defect can be recovered by replenishing toner when the comparison result in the comparison step (S2) is DA>DB will be explained.

[0177] As explained in the first embodiment, when multiple types of toner with different charging performance are mixed in the developer container 8, the toner with lower charging performance (second toner) may cause a defective image (fog image). Also, as explained in the first embodiment, the mixture of different types of toner with different charging performance in the developer container 8 can be visualized as a density difference between area A and area B in the test pattern TP.

[0178] Hereinafter, we consider a case where an image defect occurs due to the mixture of the first toner and the second toner in the developing container 8, and the flow of Fig. 19 is performed. In this case, the comparison result in the comparison step (S2) is DA>DB (area A is denser), and toner is replenished into the developing container 8 using the toner pack 40 (R3A) in the recovery step (R3). The toner to be replenished may be the first toner or the second toner, as will be explained below.

[0179] First, we will explain the case where the first toner is replenished in the recovery process (R3). When the first toner is replenished, the ratio of the first toner to the total toner in the developer container 8 increases. Also, the ratio of the first toner to the toner carried on the developing roller 4 increases, and the ratio of the second toner, which is likely to become fog toner, decreases. Therefore, by replenishing the first toner, it is possible to reduce the amount of fog toner and at least partially recover from image defects (fog images).

[0180] Next, we will explain the case where the second toner is replenished in the recovery process (R3). When the second toner is replenished, the proportion of the second toner in the total toner in the developer container 8 increases. Furthermore, while the proportion of the second toner in the toner carried on the developing roller 4 increases, the proportion of the first toner decreases. This reduces the opportunity for each toner particle of the second toner to exchange charge with the toner particles of the first toner. As a result, the proportion of toner with a low charge amount, which is prone to becoming fog toner, decreases. In other words, when the second toner is replenished in the state shown in Figure 12(b), the peak p2' with a low charge amount shifts to the negative polarity (high charge side), and the proportion of toner particles with a charge amount close to zero decreases. Therefore, by replenishing the second toner, the fog toner can be reduced and image defects (fog images) can be at least partially recovered.

[0181] (Summary of this Example) Thus, in this embodiment, when an image defect occurs and it can be determined that the cause of the image defect is the mixing of different types of toner, new toner is replenished (R3A) as a recovery step (R3). In other words, if it is visually recognized in the comparison step (S2) that the density DA in area A (first area) is higher than the density DB in area B (second area) under conditions of illuminance of 30 lux or more, as in Example 1, a replenishment step (R3A) is executed to replenish toner to the developer container 8 (toner storage unit). This makes it possible to recover from an image defect (fog image) caused by the mixing of different types of toner.

[0182] In other words, this embodiment provides a recovery method capable of recovering from image defects caused by the mixture of multiple types of toner, and can recover from image defects without replacing the process unit 9, which is one of the common methods for dealing with image defects.

[0183] The comparison method in the comparison step (S2) is not limited to visual inspection as described in the first embodiment, but may also be comparison with a standard image of a prepared judgment chart or density measurement using a densitometer. That is, in the comparison step (S2), if the density DA of region A (first region) is higher than the density DB of region B (second region) and the difference between the density DA and the density DB satisfies a predetermined condition, the replenishing step (R3A) may be executed. This makes it possible to repair image defects (fog images) caused by the mixing of different toners.

[0184] Furthermore, according to this embodiment, if it cannot be determined that the cause of the image defect is the mixing of different types of toner, the process unit 9 is replaced (R3B) as a recovery step (R3). That is, if it is not visually recognized in the comparison step (S2) that the density DA of area A (first area) is higher than the density DB of area B (second area) under the above-mentioned conditions, a replacement step (R3B) is executed to replace at least a part of the image forming mechanism of the image forming apparatus 100. This makes it possible to recover from image defects caused by reasons other than the mixing of different types of toner.

[0185] (Variation) In this embodiment, the process unit 9 is replaced when the comparison step (S2) does not result in DA > DB. However, the replacement target in the replacement step (R3B) can be changed depending on the specific configuration of the image forming apparatus 100. In other words, in the replacement step (R3B), at least a portion of the image forming mechanism of the image forming apparatus 100 may be replaced in a unit other than the process unit 9 to resolve the image defect. The "image forming mechanism" refers to the entire set of devices, units, and components required to perform any of the steps in the electrophotographic process. In this embodiment, the image forming mechanism includes the process unit 9, the scanner unit 10, the transfer roller 13, and the fixing device 14. For example, if the developing device 20 can be attached and detached independently of the other units in the apparatus main body M, only the developing device 20 may be replaced when the comparison step (S2) does not result in DA > DB. Furthermore, if the component causing the image defect can be identified, only that component (e.g., only the photosensitive drum 1 or only the charging roller 2) may be replaced.

[0186] Furthermore, if the comparison step (S2) shows that DA is not greater than DB, that is, if it cannot be determined that the cause of the image defect is due to the mixing of different types of toner, and if the cause of the image defect can be identified, then a measure other than the replacement step (S3B) may be taken depending on the cause. For example, if the cause of the image defect is dirt on the surface of the photosensitive drum 1 and the dirt can be removed by cleaning, the service technician may clean the photosensitive drum 1.

[0187] Furthermore, depending on the toner mixture ratio at the time the image defect occurs, a single toner replenishment may not be sufficient to resolve the image defect. In such cases, the same type of toner may be replenished again to increase the ratio of the same type of toner in the developer container 8, thereby further resolving the image defect.

[0188] Furthermore, in this embodiment, it has been explained that either the first toner or the second toner may be replenished in the recovery process (R3), but in consideration of the sustainability of the effect of suppressing image defects, it is more preferable to replenish the first toner. This is because, if toner deterioration progresses during repeated image formation operations after toner replenishment, the higher the proportion of second toner in the developer container 8, the more likely image defects (fog images) tend to occur. On the other hand, if the first toner is replenished in the recovery process (R3), even if the toner deterioration progresses and charging performance decreases somewhat, the proportion of toner particles with a charge amount close to 0, which is likely to become fog toner, is less likely to increase, and image defects (fog images) are relatively less likely to occur.

[0189] Furthermore, in this embodiment, toner is replenished immediately when DA>DB in the comparison step (S2), but if DA>DB in the comparison step (S2), the amount of toner in the developer container 8 may be reduced before toner replenishment. One method for reducing the amount of toner in the developer container 8 is to physically remove the process unit 9, turn it upside down, and drop it through the replenishment port 32a. Another method for reducing the amount of toner in the developer container 8 is to continuously print images with a high print rate (for example, a solid image with 100% density). By reducing the amount of toner in the developer container 8 before toner replenishment, the ratio of different toner types mixed together is reduced, which may further improve image defects.

[0190] (Modifications regarding the locking mechanism) Incidentally, in an image forming apparatus that uses a toner supply system in which toner is supplied from the outside using a toner pack 40 (supply container) as in this embodiment, a locking mechanism 57L (FIG. 1) may be provided to restrict toner supply. When the locking mechanism 57L is in a locked state, toner supply by the user is restricted, and when the locking mechanism 57L is in an unlocked state, toner supply by the user is permitted. For example, the control unit 90 locks the locking mechanism 57L based on a detection signal from the toner remaining sensor 51 until the amount of toner remaining in the developing container 8 falls below a predetermined amount, and then unlocks the locking mechanism 57L when the amount of toner remaining falls below the predetermined amount.

[0191] An example of the locking mechanism 57L is a locking member that moves between a position where it engages with the toner pack 40 attached to the mounting portion 57 to restrict rotation of the toner pack 40 and a position where it allows rotation of the toner pack 40, and an actuator such as a solenoid that moves the locking member. Another example of the locking mechanism 57L is a cover member that can move between an open position that exposes the mounting portion 57 and a closed position that covers the mounting portion 57, and a latch member that restricts the opening and closing of the cover member. These are merely examples, and the locking mechanism 57L may be any mechanism that can be placed in a locked state that restricts toner replenishment and an unlocked state that allows toner replenishment.

[0192] In the case of the image forming apparatus 100 equipped with the locking mechanism 57L, there are cases where it is required to replenish toner in order to recover from an image defect, regardless of the amount of toner remaining in the developing container 8. Therefore, as a modified example, an image forming apparatus 100 having a function of releasing the locking mechanism 57L regardless of the amount of toner remaining in the developing container 8 will be described.

[0193] Fig. 20 is a flowchart showing the recovery flow for this modified example. Compared to the flow of the fourth embodiment (Fig. 19), this modification differs in that the unlocking step (R1) is performed when the comparison result in the comparison step (S2) is DA>DB (area A is darker). In other words, in this modified example, the unlocking step (R1) is performed when the replenishing step (R3A) is performed.

[0194] In the unlocking step (R1), the service technician issues an instruction to image forming apparatus 100 to unlock locking mechanism 57L. The instruction may be given, for example, by displaying an operation screen on a PC connected to image forming apparatus 100 and clicking an unlock button on the screen. Alternatively, the instruction may be given by operating a button on the operation screen of operation unit 300 of image forming apparatus 100. Locking mechanism 57L may be unlocked at any stage of the overall flow (for example, before comparison step (S2)) as long as it is performed before toner replenishment (R3A). Furthermore, when unlocking (R1) is performed after comparison step (S2) as shown in FIG. 20 , if the comparison result in comparison step (S2) is not DA>DB, there is no need to unlock locking mechanism 57L.

[0195] According to this modification, in the image forming apparatus 100 equipped with the locking mechanism 57L, when an image defect occurs due to the mixture of different types of toner, the image defect can be corrected by supplying toner.

[0196] (Variations related to voltage control) In this embodiment, toner supply is exemplified as the recovery process (R3) when DA>DB in the comparison process (S2), but in addition to toner supply, image defects (fog images) can also be further improved by switching the execution conditions of the image forming operation. Here, as a modified example of the fourth embodiment, an image forming apparatus 100 capable of switching the execution mode (print mode) of the image forming operation between multiple modes will be described.

[0197] Fig. 21(a) is a flowchart showing the recovery flow for this modified example. It differs from the flow of the fourth embodiment (Fig. 19) in that a mode switching step (R2) for switching the print mode is performed when the comparison result in the comparison step (S2) is DA>DB (area A is darker). That is, the recovery method of this modified example includes a mode switching step for switching the image forming operation mode between a plurality of modes with different execution conditions for the image forming operation in image forming apparatus 100, and the mode switching step (R2) is performed when the supply step (R3A) is performed.

[0198] Switching the print mode changes at least some of the conditions for executing the image forming operation. Switching the print mode in this modified example refers to, for example, increasing the DC component of the charging voltage applied to the charging roller 2 (charging member) from -1350 V, the same as in the first embodiment, to -1450 V (increasing the absolute value). A method for instructing the image forming apparatus 100 to switch modes may be, for example, by displaying an operation screen on a PC screen connected to the image forming apparatus 100 and clicking a mode switching button on the screen. Alternatively, a method for instructing the image forming apparatus 100 may be by operating a button on the operation screen of the operation unit 300 of the image forming apparatus 100. Note that if the comparison result in the comparison step (S2) is not DA>DB, the print mode is not switched.

[0199] Switching the charging voltage from -1350V to -1450V increases the surface potential (absolute value) of the photosensitive drum 1, which has been charged by the charging roller 2. This increases the potential difference Vback between the potential of the developing roller 4 at the development station N3 (development potential Vdc) and the potential of the non-exposed area on the photosensitive drum 1 (dark potential VD). The development potential Vdc is the DC component of the developing voltage applied to the developing roller 4. The potential difference Vback prevents relatively low-charge toner on the developing roller 4 from adhering to the non-exposed area on the photosensitive drum 1 as fog toner, and is also known as the fog removal contrast. Therefore, if the cause of the image defect is determined to be the presence of different toner types (S2 Yes), the image defect (fog image) can be further improved by increasing the charging voltage and widening the potential difference Vback (R2) while supplying toner (R3A).

[0200] Although an example of increasing the charging voltage has been described here, the same advantage can be obtained by increasing the DC component of the developing voltage applied to the developing roller 4 (developing member) to widen the potential difference Vback. Also, both the charging voltage and the developing voltage may be changed.

[0201] The control unit 90 may also control the mode switching step (R2) of this modified example and the unlocking step (R1 in FIG. 20) of the modified example so that they are linked to each other. Also, as shown in FIG. 21(b), the mode switching step (R4) may be performed after toner replenishment (R3A).

[0202] In this modified example, when DA>DB in the comparison step (S2), the print mode is switched in addition to toner replenishment. However, the present invention is not limited to this. When DA>DB in the comparison step (S2), only the print mode is switched (R2) without toner replenishment. In this case, although the effect of improving image defects (fog images) by toner replenishment described in the fourth embodiment cannot be obtained, the fogging toner is reduced by changing the charging voltage, so the image defects can be at least partially corrected.

[0203] (Modification regarding paper passing confirmation) As another modification, as shown in FIG. 22, when DA > DB in the comparison step (S2), a paper feed confirmation step (R5) may be performed after toner replenishment (R3A). In the paper feed confirmation step (R5), the image forming apparatus 100 performs an idle rotation operation, then prints a predetermined number of test images to confirm whether the image defect has been resolved. The idle rotation operation rotates the agitator 7, the developing roller 4, and the photosensitive drum 1 without forming an image. When the idle rotation operation is performed after toner replenishment, most of the mixed toner in the developer container 8 becomes a specific type of toner (the same type as the replenished toner), reducing the opportunity for charge transfer between different toners, and frictional charging of the newly replenished toner progresses. Therefore, the polarization of the toner charge distribution (see FIG. 12(b)) is alleviated during the idle rotation operation. The predetermined number of sheets is, for example, 30, but is not limited to this. Furthermore, the test image may be a solid white (plain) image to check for the presence or absence of a fog image.

[0204] If it is determined that the image defect has not been sufficiently resolved in the paper passing confirmation step (R5), the service technician may wait for the image defect to be resolved by performing an additional paper passing confirmation step (R5). In the above case, the service technician may also attempt to resolve the image defect by causing the image forming apparatus 100 to perform the preparatory operation described in the third embodiment, for example.

[0205] (Other variations) Furthermore, the toner replenished in the toner replenishment (R3A) as a recovery process may be a toner different from any of the multiple types of toner mixed in the developer container 8. This is because if the ratio of the newly replenished toner to the total toner in the developer container 8 is sufficiently high, image defects caused by the mixing of different types of toner can be suppressed.

[0206] Example 5 Next, a description will be given of Example 5. In Example 5, a series of procedures for selectively performing a process for recovering from image defects will be described in addition to the judgment flow described in Example 2. Hereinafter, elements with common reference symbols to Example 2 will have basically the same configurations and functions as those described in Example 2 unless otherwise specified, and differences from Example 2 will be mainly described.

[0207] [Recovery flow] A series of flows in this embodiment will be described with reference to Fig. 23. This flow will be described assuming that it will be performed by a service representative. However, the entity that performs this flow is not limited to a service representative, and it may also be performed by a user.

[0208] The service representative first prints the test pattern TP in the output step (S11). Next, in the comparison step (S12), the service representative visually compares the density DA of area A of the test pattern TP output on the recording material P with the density DB of area B of the test pattern TP output on the recording material P. That is, in the comparison step (S12), the density of the first area of ​​the pattern image output on the recording material P is compared with the density of the second area. If the comparison result in the comparison step (S12) is DA>DB (area A is darker), the service representative mounts a new toner pack 40 in the mounting portion 47 and replenishes toner (R14A) in the recovery step (R14). Up to this point, the process is the same as in the second embodiment.

[0209] On the other hand, if the comparison result in the comparison step (S12) is not DA>DB, the service technician proceeds to the print confirmation step (S13). The print confirmation step (S13) is the same as in the second embodiment. That is, the service technician checks whether an image other than the test pattern is formed inside the two reference vertical lines L of the test pattern TP output on the recording material P.

[0210] In the print confirmation step (S13), if there is a vertical line inside the two reference vertical lines L as shown in Figure 15(a), the service technician performs the recovery step (R14) by installing a new toner pack 40 in the mounting portion 57 and replenishing toner (R14A). That is, if it is determined in the second embodiment that different types of toner are mixed in the developing container 8 (S13 Yes in Figure 14), toner replenishing (R14A) is performed in this embodiment as the recovery step (R14).

[0211] On the other hand, if the vertical line is outside the two reference vertical lines L as shown in Figure 15(b) or if there is no vertical line, the service technician replaces the process unit 9 (R14B) as a recovery step (R14). In other words, if it is not determined in Example 2 that different types of toner are mixed in the developer container 8 (S13 No in Figure 14), the process unit 9 is replaced (R14B) as a recovery step (R14) in this example.

[0212] [Recovery of poor image quality by toner replenishment] In the above flow, the reason why the image defect can be corrected by replenishing toner when an image is present inside the reference vertical line L in the print checking step (S13) will be explained.

[0213] As explained in Example 2, if a first toner with a high degree of circularity and a third toner with a low degree of circularity (i.e., a more distorted shape) are mixed in the developing container 8, the third toner may become caught in the developing blade 6, causing a vertical line-shaped image defect inside the reference vertical line L.

[0214] Consider the following case where a vertical line-shaped image defect occurs due to the mixing of the first toner and the third toner in the developer container 8, and the flow of Figure 23 is performed. In this case, the comparison result in the comparison step (S12) is not DA>DB, and the confirmation result in the print confirmation step (S13) is that a vertical line is present (S13Yes), and toner replenishment (R14A) is performed as the recovery step (R14). As will be explained below, the toner to be replenished is preferably the first toner.

[0215] First, we will explain the case where the first toner is replenished in the recovery process (R14). When the first toner is replenished, the ratio of the first toner to the total toner in the developer container 8 increases. Also, the ratio of the first toner to the toner carried on the developer roller 4 increases. The third toner caught in the developer blade 6 is gradually removed from the opposing portion of the developer blade 6 and the developer roller 4 as the developer roller 4 rotates. When the amount of the third toner on the developer roller 4 becomes sufficiently reduced and the first toner becomes dominant on the developer roller 4, vertical line-shaped image defects caused by toner caught in the developer blade 6 are eliminated or suppressed.

[0216] Next, we will explain the case where the third toner is replenished in the recovery process (R14). When the third toner is replenished, the ratio of the third toner to the total toner in the developer container 8 increases. Also, the ratio of the third toner to the toner carried on the development roller 4 increases. In this case, the toner jamming in the development blade 6 is not improved, and it is thought that the vertical line-shaped image defects caused by the toner jamming are not resolved.

[0217] However, the toner replenished in the recovery process (R14) is not limited to the first toner. Any toner that is not easily caught by the developing blade 6, that is, toner with a high degree of circularity, may be used. For example, the toner replenished in the recovery process (R14) preferably has an average circularity of 0.96 or more, as defined by the above-mentioned formula.

[0218] (Variation) In the fifth embodiment, a series of flows including a recovery process for image defects based on the second embodiment has been described. However, a series of flows including a recovery process for image defects may also be performed based on the third embodiment. In this case, the flow is as shown in Figure 24. If it is determined in the third embodiment that a different type of toner is present in the developer container 8 (Yes in S22, Yes in S25, or Yes in S26), the service technician replenishes toner (R27A) as a recovery process (R27). If it is not determined in the third embodiment that a different type of toner is present in the developer container 8 (No in S26), the service technician replaces the process unit 9 (R27B) as a recovery process (R27).

[0219] This provides the same advantages as in the third embodiment, such as improved accuracy of determination, and allows image defects to be repaired by an appropriate method depending on the cause of the image defects.

[0220] Furthermore, the unlocking step, mode switching step, and paper passage confirmation step described in the modified example of the fourth embodiment may be combined with the fifth embodiment or the above modified example. As an example, FIG. 25 shows a flow in which the mode switching step and paper passage confirmation step are combined with the flow of the modified example (FIG. 24). If it is determined in this flow that different types of toner are present in the developer container 8 (Yes in S22, Yes in S25, or Yes in S26), the mode switching step (R26), toner supply (R27A) as a recovery step (R27), and paper passage confirmation step (R28) are executed. The control unit 90 may perform control so that the mode switching step (R26) and the unlocking step of the modified example (R1 in FIG. 20) are linked to each other.

[0221] This makes it possible to obtain the advantages of each of the modifications and to recover from the image defect in an appropriate manner depending on the cause of the image defect.

[0222] (Other variations) In the above-described embodiments, the image forming apparatus 100 is a direct-transfer monochrome laser beam printer. However, the image forming apparatus may be an intermediate transfer type in which a toner image formed on the photosensitive drum 1 is transferred to a recording material via an intermediate transfer body such as an intermediate transfer belt. The image forming apparatus may also be a color printer that forms color images using multiple colors of toner. In the case of a color printer, a test pattern TP is created for each color of toner, and the presence or absence of mixed toners is determined for each color of toner. In this case, the quantity compared visually or using a measuring instrument in the comparison process is not limited to image density, but may also be color information. For example, a spectrophotometer may be used to determine the lightness or color coordinates of halftones in areas A and B, and then the lightness or color coordinates between areas A and B may be compared.

[0223] Furthermore, in each of the above-described embodiments, the image forming apparatus 100 has been described on the assumption that it is a cleaner-less configuration, but the determination method of the present disclosure may also be applied to an image forming apparatus equipped with a cleaning device that collects residual toner from the photosensitive drum 1.

[0224] Furthermore, in the above-described embodiments, it has been described that a service person (i.e., a human being) executes each step of the determination method described in each flowchart, but some or all of the determination method may be executed by the image forming apparatus 100. For example, the image forming apparatus 100 may be equipped with a densitometer capable of measuring the density of a halftone image, and the image forming apparatus 100 may automatically execute the comparison steps (S2, S12, S25, S34) when the determination mode is executed.

[0225] Furthermore, in the above-described embodiments, an external supply system configuration has been exemplified in which toner can be supplied to the developer container 8 (toner storage unit) inside the image forming apparatus using a toner pack 40 (supply container) from outside the image forming apparatus. However, the image forming apparatus may also be configured such that a supply container (sometimes called a toner cartridge or toner bottle) containing replenishment toner can be attached to and detached from the image forming apparatus main body. In this case, toner is supplied to the developer container 8 from the supply container installed inside the image forming apparatus main body. Even in this case, if the type of toner already contained in the developer container 8 differs from the type of toner newly supplied from the supply container, or if the toner in the developer container 8 has deteriorated, image defects due to the mixing of different types of toner can occur. Therefore, the determination flow described in each embodiment can be used to determine whether the image defects are due to the mixing of different types of toner.

[0226] (Other embodiments) The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program.The present invention can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0227] Summary of the Disclosure The present disclosure includes at least the following: (Configuration 1) 1. A method for determining whether a plurality of types of toner are mixed in a toner storage unit of an image forming apparatus capable of replenishing toner using a replenishing container, the method comprising: an output step of outputting onto a recording material a pattern image including a first region in which a halftone image is formed and a second region in which a halftone image consisting of dots having an average dot size smaller than that of the first region, using the image forming device; a comparing step of comparing the density of the first region with the density of the second region of the pattern image output onto the recording material; a determining step of determining that a plurality of types of toner are mixed in the toner storage unit when the density of the first region is visually recognized as being higher than the density of the second region in the comparing step under a condition of an illuminance of 30 lux or more; Including, A determination method characterized by: (Configuration 2) In the pattern image, the first region and the second region are adjacent to each other. 2. The determination method according to claim 1, (Configuration 3) In the pattern image, one of the first region and the second region is sandwiched between the other of the first region and the second region. 3. The determination method according to configuration 1 or 2. (Configuration 4) the halftone image in the first region is made up of dots with an average dot size of 3x3 pixels or more, and the halftone image in the second region is made up of dots with an average dot size of 2x2 pixels or less; 4. The determination method according to any one of configurations 1 to 3. (Configuration 5) a ratio of pixels on which dots are formed to all pixels in the first region is equal to or greater than a ratio of pixels on which dots are formed to all pixels in the second region; 5. The determination method according to any one of configurations 1 to 4. (Configuration 6) the pattern image is formed at the center of the recording material in the main scanning direction during image formation; 6. The method for determining whether a target object is a target object, comprising: (Configuration 7) the plurality of types of toner include a first toner and a second toner having lower charging performance than the first toner; 7. The determination method according to any one of configurations 1 to 6, (Configuration 8) the toner particles of the first toner have a core particle and a surface layer that contains an organosilicon polymer and covers the surface of the core particle; the toner particles of the second toner do not have a surface layer containing an organosilicon polymer; 8. The determination method according to configuration 7. (Configuration 9) the pattern image includes a boundary line indicating a boundary of a predetermined region in a main scanning direction during image formation, The determination method further includes a confirmation step of confirming whether or not an image other than the pattern image exists within the predetermined area, If an image other than the pattern image is present in the predetermined area in the confirmation step, it is determined that a plurality of types of toner are mixed in the toner storage section. 9. The determination method according to any one of configurations 1 to 8. (Configuration 10) the predetermined area is a maximum area in which the image forming apparatus can form an image in the main scanning direction, or an area inside the maximum area; The determination method according to configuration 9, characterized in that: (Configuration 11) the plurality of types of toner include a first toner and a third toner having an average circularity lower than that of the first toner; 11. The determination method according to configuration 9 or 10. (Configuration 12) the first toner is a polymerized toner, the third toner is a pulverized toner; 12. The determination method according to claim 11. (Configuration 13) 1. A method for determining whether a plurality of types of toner are mixed in a toner storage unit of an image forming apparatus capable of replenishing toner using a replenishing container, the method comprising: an output step of outputting onto a recording material a pattern image including a first region in which a halftone image is formed and a second region in which a halftone image consisting of dots having an average dot size smaller than that of the first region, using the image forming device; a comparing step of comparing the density of the first region with the density of the second region of the pattern image output onto the recording material; a determining step of determining that a plurality of types of toner are mixed in the toner storage unit when the density of the first region is higher than the density of the second region in the comparing step and the difference between the density of the first region and the density of the second region satisfies a predetermined condition; Including, A determination method characterized by: (Configuration 14) In the comparing step, the density of the first region and the density of the second region measured using a densitometer are compared. 14. The determination method according to claim 13. (Configuration 15) the predetermined condition is that the difference between the density of the first region and the density of the second region measured using the densitometer is 0.01 or more; 15. The determination method according to configuration 14. (Configuration 16) In the comparing step, a judgment chart prepared in advance and including a plurality of standard images set to different density levels is used to compare one of the plurality of standard images closest to the density of the first region with one of the plurality of standard images closest to the density of the second region. 14. The determination method according to claim 13. (Configuration 17) the predetermined condition is that the density level in the judgment chart differs by at least one level between the standard image among the plurality of standard images that is closest to the density of the first region and the standard image among the plurality of standard images that is closest to the density of the second region; 17. The determination method according to claim 16, (Configuration 18) The method further includes a preliminary operation execution step of causing the image forming apparatus to execute a preliminary operation for removing fog toner adhering to a charging roller that charges a photosensitive drum, The output step is performed after the preliminary operation execution step. 18. The determination method according to any one of configurations 1 to 17. (Configuration 19) the preliminary operation includes a first operation of rotating the charging roller and the photosensitive drum so that the charging roller and the photosensitive drum rub against each other while applying a voltage of the same polarity as the normal polarity of the toner to the charging roller and applying a voltage of the opposite polarity to the normal polarity of the toner to the developing roller; 19. The determination method according to configuration 18. (Configuration 20) the preliminary operation includes a second operation of alternately applying a voltage of the same polarity as the normal polarity of the toner and a voltage of a polarity opposite to the normal polarity to the charging roller, and rotating the photosensitive drum while applying a voltage of the opposite polarity to the normal polarity of the toner to the developing roller; 20. The determination method according to configuration 18 or 19. (Configuration 21) If the level of the image other than the pattern image generated in the predetermined area when the pattern image is output after the preliminary operation execution step is improved compared to the image other than the pattern image generated in the predetermined area when the pattern image is output before the preliminary operation execution step, it is determined that multiple types of toner are mixed in the toner storage unit. 21. The determination method according to any one of configurations 18 to 20. (Configuration 22) 1. A method for determining whether a plurality of types of toner are mixed in a toner storage unit of an image forming apparatus capable of replenishing toner using a replenishing container, the method comprising: a first output step of outputting, onto a first recording material, a first pattern image including a boundary line indicating a boundary of a predetermined area in a main scanning direction during image formation, using the image forming apparatus; a first confirmation step of confirming whether or not an image other than the first pattern image is present within the predetermined region of the first recording material; a determination step of determining whether or not a plurality of types of toner are mixed in the toner storage unit based on the result of the first confirmation step; Including, A determination method characterized by: (Configuration 23) a preliminary operation execution step of causing the image forming apparatus to execute a preliminary operation for removing fog toner adhering to a charging roller that charges a photosensitive drum after the first output step; a second output step of outputting, after the preliminary operation, onto a second recording material, using the image forming device, a first region where a halftone image is to be formed, a second region where a halftone image consisting of dots having an average dot size smaller than that of the first region where a halftone image is to be formed, and a second pattern image including the boundary line; a second confirmation step of confirming whether or not an image other than the second pattern image is present within the predetermined region of the second recording material; a comparing step of comparing the density of the first region with the density of the second region of the second pattern image output onto the second recording material; Further comprising: In the determination step, it is determined whether or not a plurality of types of toner are mixed in the toner storage unit based on the results of the first confirmation step, the second confirmation step, and the comparison step. 23. The determination method according to claim 22. (Configuration 24) In the first confirmation step, if an image other than the first pattern image is present in the predetermined area, in the second confirmation step, if an image other than the second pattern image is present in the predetermined area, and in the comparison step, if the density of the first area is higher than the density of the second area, it is determined in the determination step that multiple types of toner are mixed in the toner storage unit. 24. The determination method according to claim 23. (Configuration 25) a preliminary operation execution step of executing, after the first output step, a preliminary operation for removing fogging toner adhering to a charging roller that charges a photosensitive drum using the image forming apparatus; a second output step of outputting a second pattern image including the boundary line onto a second recording material using the image forming apparatus after the preliminary operation; a second confirmation step of confirming whether or not an image other than the second pattern image is present within the predetermined region of the second recording material; Further comprising: If an image other than the first pattern image is present in the predetermined area in the first confirmation step, and if a level of the image other than the second pattern image generated in the predetermined area of ​​the second recording material in the second confirmation step is improved compared to the image other than the first pattern image generated in the predetermined area of ​​the first recording material, it is determined in the determination step that multiple types of toner are mixed in the toner storage unit, and if a level of the image other than the second pattern image generated in the predetermined area of ​​the second recording material is not improved, it is determined in the determination step that multiple types of toner are not mixed in the toner storage unit. 23. The determination method according to claim 22. (Configuration 26) A recovery method for recovering an image defect in an image forming apparatus capable of replenishing toner in a toner storage section within the image forming apparatus using a replenishing container, comprising: an output step of outputting onto a recording material a pattern image including a first region in which a halftone image is formed and a second region in which a halftone image consisting of dots having an average dot size smaller than that of the first region, using the image forming device; a comparing step of comparing the density of the first region with the density of the second region of the pattern image output onto the recording material; a replenishing step of replenishing toner in the toner storage section; Including, When the density of the first region is visually recognized as being higher than the density of the second region under an illuminance of 30 lux or more in the comparison step, the replenishment step is carried out. A recovery method characterized by: (Configuration 27) The method further includes a replacement step of replacing at least a part of an image forming mechanism of the image forming apparatus, and performing the exchanging step when the density of the first region is not visually recognized as being higher than the density of the second region under the conditions in the comparing step. 27. The recovery method according to claim 26. (Configuration 28) When the replenishing step is performed in a state in which a first toner and a second toner having lower charging performance than the first toner are mixed in the toner storage unit, the toner to be replenished to the toner storage unit is either the first toner or the second toner. 28. The recovery method according to claim 26 or 27. (Configuration 29) the pattern image includes a boundary line indicating a boundary of a predetermined region in a main scanning direction during image formation, The recovery method further includes a confirmation step of confirming whether or not an image other than the pattern image exists within the predetermined area; If an image other than the pattern image is found in the predetermined area in the checking step, the supplying step is executed. 29. The recovery method according to any one of claims 26 to 28. (Configuration 30) When the replenishing step is performed in a state in which a first toner and a third toner having an average circularity lower than that of the first toner are mixed in the toner storage unit, the toner to be replenished to the toner storage unit is the first toner. 30. The recovery method according to claim 29. (Configuration 31) A recovery method for recovering an image defect in an image forming apparatus capable of replenishing toner in a toner storage section within the image forming apparatus using a replenishing container, comprising: an output step of outputting onto a recording material a pattern image including a first region in which a halftone image is formed and a second region in which a halftone image consisting of dots having an average dot size smaller than that of the first region, using the image forming device; a comparing step of comparing the density of the first region with the density of the second region of the pattern image output onto the recording material; a replenishing step of replenishing toner in the toner storage section; Including, The replenishing step is executed when the concentration of the first region is higher than the concentration of the second region in the comparing step, and when the difference between the concentration of the first region and the concentration of the second region satisfies a predetermined condition. A recovery method characterized by: (Configuration 32) A recovery method for recovering an image defect in an image forming apparatus capable of replenishing toner in a toner storage section within the image forming apparatus using a replenishing container, comprising: a first output step of outputting, onto a first recording material, a first pattern image including a boundary line indicating a boundary of a predetermined area in a main scanning direction during image formation, using the image forming apparatus; a first confirmation step of confirming whether or not an image other than the first pattern image is present within the predetermined region of the first recording material; a replenishing step of replenishing toner in the toner storage section; Including, When an image other than the first pattern image is present in the predetermined area in the first confirmation step, the supply step is executed. A recovery method characterized by: (Configuration 33) a preliminary operation execution step of causing the image forming apparatus to execute a preliminary operation for removing fog toner adhering to a charging roller that charges a photosensitive drum after the first output step; a second output step of outputting, after the preliminary operation, onto a second recording material, using the image forming device, a first region where a halftone image is to be formed, a second region where a halftone image consisting of dots having an average dot size smaller than that of the first region where a halftone image is to be formed, and a second pattern image including the boundary line; a second confirmation step of confirming whether or not an image other than the second pattern image is present within the predetermined region of the second recording material; a comparing step of comparing the density of the first region with the density of the second region of the second pattern image output onto the second recording material; Further comprising: The supplying step is executed in each of the following cases: when an image other than the first pattern image is present in the predetermined area in the first confirmation step; when an image other than the second pattern image is present in the predetermined area in the second confirmation step; and when it is visually recognized that the density of the first area is higher than the density of the second area in the comparison step. 33. The recovery method according to claim 32. (Configuration 34) the image forming apparatus includes a locking mechanism that can be in a locked state that restricts toner replenishment to the toner accommodating unit using the replenishment container and an unlocked state that allows the toner replenishment, The recovery method further includes an unlocking step of changing the locking mechanism from the locked state to the unlocked state, The unlocking step is executed when the supplying step is executed. 34. The recovery method of any one of claims 29 to 33. (Configuration 35) The recovery method further includes a mode switching step of switching a mode of the image forming operation among a plurality of modes that have different execution conditions for the image forming operation in the image forming apparatus, The mode switching step is performed when the supplying step is performed. 35. The recovery method of any one of configurations 29 to 34. (Configuration 36) the image forming apparatus includes a photoreceptor, a charging member that charges the surface of the photoreceptor, and a developing member that supplies toner to the photoreceptor and develops a latent image on the surface of the photoreceptor into a toner image; In the mode switching step, the absolute value of the DC component of the voltage applied to the charging member is increased and / or the absolute value of the DC component of the voltage applied to the developing member is decreased. 36. The recovery method according to claim 35, (Configuration 37) the recovery method further includes a paper passing confirmation step of forming a predetermined image on a recording material using the image forming apparatus to confirm the improvement of the image defect after the supply step. 37. The recovery method of any one of configurations 29 to 36. [Explanation of symbols]

[0228] S1...output process, S2...comparison process, S3...judgment process, R3A...supply process, TP...pattern image (judgment pattern)

Claims

1. 1. A method for determining whether a plurality of types of toner are mixed in a toner storage unit of an image forming apparatus capable of replenishing toner using a replenishing container, the method comprising: an output step of outputting onto a recording material a pattern image including a first region in which a halftone image is formed and a second region in which a halftone image consisting of dots having an average dot size smaller than that of the first region, using the image forming device; a comparing step of comparing the density of the first region with the density of the second region of the pattern image output onto the recording material; a determining step of determining that a plurality of types of toner are mixed in the toner storage unit when the density of the first region is visually recognized as being higher than the density of the second region in the comparing step under a condition of an illuminance of 30 lux or more; Including, A determination method characterized by:

2. In the pattern image, the first region and the second region are adjacent to each other. The method according to claim 1 .

3. In the pattern image, one of the first region and the second region is sandwiched between the other of the first region and the second region. The method according to claim 1 .

4. the halftone image in the first region is made up of dots having an average dot size of 3×3 pixels or more, and the halftone image in the second region is made up of dots having an average dot size of 2×2 pixels or less; The method according to claim 1 .

5. a ratio of pixels on which dots are formed to all pixels in the first region is equal to or greater than a ratio of pixels on which dots are formed to all pixels in the second region; The method according to claim 1 .

6. the pattern image is formed at the center of the recording material in the main scanning direction during image formation; The method according to claim 1 .

7. the plurality of types of toner include a first toner and a second toner having lower charging performance than the first toner; The method according to claim 1 .

8. the toner particles of the first toner have a core particle and a surface layer that contains an organosilicon polymer and covers the surface of the core particle; the toner particles of the second toner do not have a surface layer containing an organosilicon polymer; The method according to claim 7 .

9. the pattern image includes a boundary line indicating a boundary of a predetermined region in a main scanning direction during image formation, The determination method further includes a confirmation step of confirming whether or not an image other than the pattern image exists within the predetermined area, If an image other than the pattern image is present in the predetermined area in the confirmation step, it is determined that a plurality of types of toner are mixed in the toner storage section. The method according to any one of claims 1 to 8.

10. the predetermined area is a maximum area in which the image forming apparatus can form an image in the main scanning direction, or an area inside the maximum area; The determination method according to claim 9,

11. the plurality of types of toner include a first toner and a third toner having an average circularity lower than that of the first toner; The determination method according to claim 9 .

12. the first toner is a polymerized toner, the third toner is a pulverized toner; The method according to claim 11 .

13. 1. A method for determining whether a plurality of types of toner are mixed in a toner storage unit of an image forming apparatus capable of replenishing toner using a replenishing container, the method comprising: an output step of outputting onto a recording material a pattern image including a first region in which a halftone image is formed and a second region in which a halftone image consisting of dots having an average dot size smaller than that of the first region, using the image forming device; a comparing step of comparing the density of the first region with the density of the second region of the pattern image output onto the recording material; a determining step of determining that a plurality of types of toner are mixed in the toner storage unit when the density of the first region is higher than the density of the second region in the comparing step and the difference between the density of the first region and the density of the second region satisfies a predetermined condition; Including, A determination method characterized by:

14. In the comparing step, the density of the first region and the density of the second region measured using a densitometer are compared. The method according to claim 13 .

15. the predetermined condition is that the difference between the density of the first region and the density of the second region measured using the densitometer is 0.01 or more; The method according to claim 14 .

16. In the comparing step, a judgment chart prepared in advance and including a plurality of standard images set to different density levels is used to compare one of the plurality of standard images closest to the density of the first region with one of the plurality of standard images closest to the density of the second region. The method according to claim 13 .

17. the predetermined condition is that the density level in the judgment chart differs by at least one level between the standard image among the plurality of standard images that is closest to the density of the first region and the standard image among the plurality of standard images that is closest to the density of the second region; 17. The method of claim 16.

18. The method further includes a preliminary operation execution step of causing the image forming apparatus to execute a preliminary operation for removing fog toner adhering to a charging roller that charges a photosensitive drum, The output step is performed after the preliminary operation execution step. The method according to any one of claims 1 to 8.

19. the preliminary operation includes a first operation of rotating the charging roller and the photosensitive drum so that the charging roller and the photosensitive drum rub against each other while applying a voltage of the same polarity as the normal polarity of the toner to the charging roller and applying a voltage of the opposite polarity to the normal polarity of the toner to the developing roller; 20. The method of claim 18.

20. the preliminary operation includes a second operation of alternately applying a voltage having the same polarity as the normal polarity of the toner and a voltage having a polarity opposite to the normal polarity to the charging roller, and rotating the photosensitive drum while applying a voltage having a polarity opposite to the normal polarity of the toner to the developing roller; 20. The method of claim 18.

21. If the level of the image other than the pattern image generated in the predetermined area when the pattern image is output after the preliminary operation execution step is improved compared to the image other than the pattern image generated in the predetermined area when the pattern image is output before the preliminary operation execution step, it is determined that multiple types of toner are mixed in the toner storage unit.

20. The method of claim 18.

22. 1. A method for determining whether a plurality of types of toner are mixed in a toner storage unit of an image forming apparatus capable of replenishing toner using a replenishing container, the method comprising: a first output step of outputting, onto a first recording material, a first pattern image including a boundary line indicating a boundary of a predetermined region in a main scanning direction during image formation, using the image forming apparatus; a first confirmation step of confirming whether or not an image other than the first pattern image is present within the predetermined region of the first recording material; a determining step of determining whether or not a plurality of types of toner are mixed in the toner storage unit based on a result of the first checking step; Including, A determination method characterized by:

23. a preliminary operation execution step of causing the image forming apparatus to execute a preliminary operation for removing fog toner adhering to a charging roller that charges a photosensitive drum after the first output step; a second output step of outputting, after the preliminary operation, onto a second recording material, using the image forming device, a first region where a halftone image is to be formed, a second region where a halftone image consisting of dots having an average dot size smaller than that of the first region where a halftone image is to be formed, and a second pattern image including the boundary line; a second confirmation step of confirming whether or not an image other than the second pattern image is present within the predetermined region of the second recording material; a comparing step of comparing the density of the first region with the density of the second region of the second pattern image output onto the second recording material; Further comprising: In the determination step, it is determined whether or not a plurality of types of toner are mixed in the toner storage unit based on the results of the first confirmation step, the second confirmation step, and the comparison step.

23. The method of claim 22.

24. If an image other than the first pattern image is present in the predetermined area in the first confirmation step, if an image other than the second pattern image is present in the predetermined area in the second confirmation step, and if the density of the first area is higher than the density of the second area in the comparison step, it is determined in the determination step that multiple types of toner are mixed in the toner storage unit.

24. The method of claim 23.

25. a preliminary operation execution step of executing, after the first output step, a preliminary operation for removing fogging toner adhering to a charging roller that charges a photosensitive drum using the image forming apparatus; a second output step of outputting a second pattern image including the boundary line onto a second recording material using the image forming apparatus after the preliminary operation; a second confirmation step of confirming whether or not an image other than the second pattern image is present within the predetermined region of the second recording material; Further comprising: If an image other than the first pattern image is present in the predetermined area in the first confirmation step, and if the level of the image other than the second pattern image generated in the predetermined area of ​​the second recording material in the second confirmation step is improved compared to the image other than the first pattern image generated in the predetermined area of ​​the first recording material, it is determined in the determination step that multiple types of toner are mixed in the toner storage unit, and if the level of the image other than the second pattern image generated in the predetermined area of ​​the second recording material is not improved, it is determined in the determination step that multiple types of toner are not mixed in the toner storage unit.

23. The method of claim 22.

26. A recovery method for recovering an image defect in an image forming apparatus capable of replenishing toner in a toner storage section within the image forming apparatus using a replenishing container, comprising: an output step of outputting onto a recording material a pattern image including a first region in which a halftone image is formed and a second region in which a halftone image consisting of dots having an average dot size smaller than that of the first region, using the image forming device; a comparing step of comparing the density of the first region with the density of the second region of the pattern image output onto the recording material; a replenishing step of replenishing toner in the toner storage section; Including, When the density of the first region is visually recognized as being higher than the density of the second region under an illuminance of 30 lux or more in the comparison step, the replenishment step is carried out. A recovery method characterized by:

27. The method further includes a replacement step of replacing at least a part of an image forming mechanism of the image forming apparatus, and performing the replacing step when the density of the first region is not visually recognized as being higher than the density of the second region under the conditions in the comparing step.

27. The recovery method of claim 26.

28. When the replenishing step is performed in a state in which a first toner and a second toner having lower charging performance than the first toner are mixed in the toner storage unit, the toner to be replenished to the toner storage unit is either the first toner or the second toner.

27. The recovery method of claim 26.

29. the pattern image includes a boundary line indicating a boundary of a predetermined region in a main scanning direction during image formation, The recovery method further includes a confirmation step of confirming whether or not an image other than the pattern image exists within the predetermined area; If an image other than the pattern image is found in the predetermined area in the checking step, the supplying step is executed.

27. The recovery method of claim 26.

30. When the replenishing step is performed in a state in which a first toner and a third toner having an average circularity lower than that of the first toner are mixed in the toner storage unit, the toner to be replenished to the toner storage unit is the first toner.

30. The recovery method of claim 29.

31. A recovery method for recovering an image defect in an image forming apparatus capable of replenishing toner in a toner storage section within the image forming apparatus using a replenishing container, comprising: an output step of outputting onto a recording material a pattern image including a first region in which a halftone image is formed and a second region in which a halftone image consisting of dots having an average dot size smaller than that of the first region, using the image forming device; a comparing step of comparing the density of the first region with the density of the second region of the pattern image output onto the recording material; a replenishing step of replenishing toner in the toner storage section; Including, the replenishing step is executed when the concentration of the first region is higher than the concentration of the second region in the comparing step, and when a difference between the concentration of the first region and the concentration of the second region satisfies a predetermined condition. A recovery method characterized by:

32. A recovery method for recovering an image defect in an image forming apparatus capable of replenishing toner in a toner storage section within the image forming apparatus using a replenishing container, comprising: a first output step of outputting, onto a first recording material, a first pattern image including a boundary line indicating a boundary of a predetermined region in a main scanning direction during image formation, using the image forming apparatus; a first confirmation step of confirming whether or not an image other than the first pattern image is present within the predetermined region of the first recording material; a replenishing step of replenishing toner in the toner storage section; Including, the supplying step is executed when an image other than the first pattern image is present in the predetermined area in the first confirmation step. A recovery method characterized by:

33. a preliminary operation execution step of causing the image forming apparatus to execute a preliminary operation for removing fog toner adhering to a charging roller that charges a photosensitive drum after the first output step; a second output step of outputting, after the preliminary operation, onto a second recording material, using the image forming device, a first region where a halftone image is to be formed, a second region where a halftone image consisting of dots having an average dot size smaller than that of the first region where a halftone image is to be formed, and a second pattern image including the boundary line; a second confirmation step of confirming whether or not an image other than the second pattern image is present within the predetermined region of the second recording material; a comparing step of comparing the density of the first region with the density of the second region of the second pattern image output onto the second recording material; Further comprising: The supplying step is executed in each of the following cases: when an image other than the first pattern image is present in the predetermined area in the first confirmation step; when an image other than the second pattern image is present in the predetermined area in the second confirmation step; and when it is visually recognized that the density of the first area is higher than the density of the second area in the comparison step.

33. The recovery method of claim 32.

34. the image forming apparatus includes a locking mechanism that can be in a locked state that restricts toner replenishment to the toner accommodating unit using the replenishment container and an unlocked state that allows the toner replenishment, The recovery method further includes an unlocking step of changing the locking mechanism from the locked state to the unlocked state, The unlocking step is executed when the supplying step is executed.

34. The method of claim 29, wherein the first and second electrodes are connected to a first electrode.

35. The recovery method further includes a mode switching step of switching a mode of the image forming operation among a plurality of modes that have different execution conditions for the image forming operation in the image forming apparatus, The mode switching step is performed when the supplying step is performed.

34. The method of claim 29, wherein the first and second electrodes are connected to a first electrode.

36. the image forming apparatus includes a photoreceptor, a charging member that charges the surface of the photoreceptor, and a developing member that supplies toner to the photoreceptor and develops a latent image on the surface of the photoreceptor into a toner image; In the mode switching step, the absolute value of the DC component of the voltage applied to the charging member is increased and / or the absolute value of the DC component of the voltage applied to the developing member is decreased.

36. The recovery method of claim 35.

37. the recovery method further includes a paper passing confirmation step of forming a predetermined image on a recording material using the image forming apparatus to confirm the improvement of the image defect after the supply step.

34. The method of claim 29, wherein the first and second electrodes are connected to a first electrode.

Images