Determination method and recovery method

Abstract

Determination methods and recovery methods are disclosed. A determination method includes outputting a pattern image including a first region in which a halftone image is formed and a second region in which another halftone image is formed, the halftone image of the second region being constituted by dots whose average dot size is smaller than the average dot size of dots constituting the halftone image of the first region, a density of a first region and a density of a second region in a pattern image output on a recording material are compared, and in a case where a visual density of a halftone image of the first region is higher than a visual density of the second region, it is determined that a plurality of types of toner are mixed in a toner storage portion.

Description

Technical Field

[0001] The present invention relates to a determination method for determining whether a plurality of toners are mixed in a toner storage portion in an image forming apparatus and a recovery method for the image forming apparatus to recover from an image defect. Background Art

[0002] Examples of methods for replenishing developer (toner) to an image forming device include a cartridge system and an external replenishment system. In the cartridge system, a processing cartridge or a toner cartridge that is attachable to and detachable from an image forming device main body is used, and when the remaining amount of developer in the cartridge is small, the cartridge is replaced with a brand new cartridge. In the external replenishment system, when the remaining amount of developer in the toner storage portion of the image forming device is small, the developer is replenished from the outside of the image forming device to the toner storage portion by using a replenishment container for storing the developer. Japanese Patent Publication No. 2020-154302 discloses a configuration for replenishing toner to an image forming device from the outside by using a toner pack as a replenishment container. Summary of the Invention

[0003] The present invention provides a determination method for determining whether mixing of a plurality of toners occurs, and can realize a recovery method for recovering from an image defect caused by the mixing of a plurality of toners.

[0004] According to one aspect of the present invention, a determination method is used to determine whether a plurality of toners are mixed in a toner storage portion in an image forming device, the toner storage portion being capable of being replenished with toner by using a replenishing container, and the determination method includes: outputting a pattern image on a recording material by using the image forming device, the pattern image including a first area in which a halftone image is formed and a second area in which another halftone image is formed, the halftone image of the second area being composed of dots having an average dot size smaller than the average dot size of dots constituting the halftone image of the first area; comparing the concentration of the first area with the concentration of the second area in the pattern image output on the recording material; and determining that the plurality of toners are mixed in the toner storage portion when the visual concentration of the halftone image of the first area is higher than the visual concentration of the second area under the condition of an illumination of 30 lux or greater in the comparison.

[0005] According to another aspect of the present invention, a determination method is used to determine whether multiple colorants are mixed in a colorant storage part in an image forming device, wherein the colorant storage part can be replenished with colorants by using a replenishing container, and the determination method includes: outputting a pattern image on a recording material by using the image forming device, the pattern image including a first area in which a halftone image is formed and a second area in which another halftone image is formed, the halftone image of the second area being composed of dots having an average dot size smaller than the average dot size of dots constituting the halftone image of the first area; comparing the concentration of the first area in the pattern image output on the recording material with the concentration of the second area; and determining that the multiple colorants are mixed in the colorant storage part when the concentration of the first area is higher than the concentration of the second area in the comparison and the difference between the concentration of the first area and the concentration of the second area meets a predetermined condition.

[0006] According to another aspect of the present invention, a determination method is used to determine whether a plurality of toners are mixed in a toner storage portion in an image forming device, the toner storage portion being capable of being replenished with toner by using a replenishing container, and the determination method includes: outputting a first pattern image on a first recording material by using the image forming device, the first pattern image including a boundary line indicating a boundary of a predetermined area in a main scanning direction of image formation; checking whether an image other than the first pattern image exists in the predetermined area on the first recording material; and determining whether the plurality of toners are mixed in the toner storage portion based on a result of the checking.

[0007] According to another aspect of the present invention, a recovery method is used to restore an image forming device from an image defect, the image forming device including a colorant storage portion capable of being replenished with colorant by using a replenishing container, and the recovery method includes: outputting a pattern image on a recording material by using the image forming device, the pattern image including a first area formed with a halftone image and a second area formed with another halftone image, the halftone image of the second area being composed of dots having an average dot size smaller than the average dot size of dots constituting the halftone image of the first area; comparing the concentration of the first area in the pattern image output on the recording material with the concentration of the second area; and replenishing the colorant storage portion with colorant, wherein the replenishment is performed when the visual density of the halftone image of the first area is higher than the visual density of the second area under the condition of an illumination of 30 lux or greater in the comparison.

[0008] According to another aspect of the present invention, a recovery method is used to restore an image forming device from an image defect, the image forming device including a colorant storage portion capable of being replenished with colorant by using a replenishing container, and the recovery method includes: outputting a pattern image on a recording material by using the image forming device, the pattern image including a first area in which a halftone image is formed and a second area in which another halftone image is formed, the halftone image of the second area being composed of dots having an average dot size smaller than the average dot size of dots constituting the halftone image of the first area; comparing the concentration of the first area in the pattern image output on the recording material with the concentration of the second area; and replenishing the colorant storage portion with colorant, wherein the replenishment is performed when the concentration of the first area is higher than the concentration of the second area in the comparison and the difference between the concentration of the first area and the concentration of the second area meets a predetermined condition.

[0009] According to another aspect of the present invention, a recovery method is used to restore an image forming device from an image defect, the image forming device including a toner storage portion capable of being replenished with toner using a replenishing container, and the recovery method includes: outputting a first pattern image on a first recording material by using the image forming device, the first pattern image including a boundary line indicating a boundary of a predetermined area in a main scanning direction of image formation; checking whether there is an image other than the first pattern image in the predetermined area on the first recording material; and replenishing the toner storage portion with toner, wherein the replenishment is performed in the event that an image other than the first pattern image is present in the predetermined area in the checking.

[0010] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic diagram of an image forming apparatus according to Example 1.

[0012] Figure 2A is a perspective view of a process unit and a toner pack according to Example 1.

[0013] Figure 2B is a front view of a process unit and a toner pack according to Example 1.

[0014] Figure 3A and Figure 3B Each is a cross-sectional view of a processing unit according to Example 1.

[0015] Figure 4is an explanatory diagram of a toner package according to Example 1.

[0016] Figure 5A is a diagram illustrating a toner package according to Example 1, Figure 5B is a diagram illustrating a first modification of the toner pack, and Figure 5C 2 is a diagram illustrating a second modification of the toner pack.

[0017] Figure 6 is a block diagram illustrating a control system of the image forming apparatus according to Example 1.

[0018] Figure 7 The determination pattern according to Example 1 is illustrated.

[0019] Figure 8A and Figure 8B is an explanatory diagram of a dot structure of each area of a determination pattern according to Example 1.

[0020] Figure 9 A modification of the determination pattern according to Example 1 is illustrated.

[0021] Figure 10 is a flowchart of a determination method according to Example 1.

[0022] Figure 11 An example of a state of a determination pattern and a determination result according to Example 1 is illustrated.

[0023] Figure 12A is a conceptual diagram illustrating toner charge distribution in the case where different kinds of toners are mixed.

[0024] Figure 12B is a conceptual diagram illustrating toner charge distribution in a case where different kinds of toners are not mixed.

[0025] Figure 13 The determination pattern according to Example 2 is illustrated.

[0026] Figure 14 A flowchart of a determination method according to Example 2 is illustrated.

[0027] Figure 15A and Figure 15B Each illustrates an example of an image defect and a determination result when a determination pattern according to Example 2 is output.

[0028] Figure 16 A modification of the determination pattern according to Example 2 is illustrated.

[0029] Figure 17 A flowchart of a determination method according to Example 3 is illustrated.

[0030] Figure 18A flowchart of a determination method according to a modification of Example 3 is illustrated.

[0031] Figure 19 A flowchart of a recovery method according to Example 4 is illustrated.

[0032] Figure 20 A flowchart of a restoration method according to a modification of Example 4 is illustrated.

[0033] Figure 21A and Figure 21B Each illustrates a flowchart of a restoration method according to a modification of Example 4.

[0034] Figure 22 A flowchart of a restoration method according to a modification of Example 4 is illustrated.

[0035] Figure 23 A flowchart of a recovery method according to Example 5 is illustrated.

[0036] Figure 24 A flowchart of a restoration method according to a modification of Example 5 is illustrated.

[0037] Figure 25 A flowchart of a restoration method according to a modification of Example 5 is illustrated. DETAILED DESCRIPTION

[0038] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings.

[0039] Example 1

[0040] Example 1 will be described. Figure 1 is a schematic diagram illustrating a cross section of an image forming apparatus 100 according to Example 1. The image forming apparatus 100 is a monochrome laser beam printer of an electronic photographic system. For example, the image forming apparatus 100 forms an image on the recording material P based on image information received from an external device when conveying an A4-sized recording material P by longitudinal feeding, by using a toner used as a developer. As the recording material P (recording medium), a variety of sheet materials of different sizes and materials can be used. Examples of the sheet material include surface-treated sheet materials used as coated paper sheets, irregularly shaped sheet materials such as envelopes and index paper sheets, plastic films, and cloth. In addition, 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 conveying direction of the recording material P (long edge feeding).

[0041] like Figure 1As shown in FIG. 1 , the image forming apparatus 100 includes a process unit 9 and an apparatus body M that houses the process unit 9. The process unit 9 includes a photosensitive drum 1 and a plurality of process sections disposed around the photosensitive drum 1. In this example, the plurality of process sections include a charging roller 2, a developing unit 20, a charge removal unit 11, and a brush member 12. Furthermore, the image forming apparatus 100 includes a mounting portion 57 and a locking mechanism 57L. In Example 4, the locking mechanism 57L will be described.

[0042] In this example, the process unit 9 is configured to be attachable to and detachable from the apparatus main body M. This configuration is not limited thereto, and the process unit 9 may be configured to be non-detachable from the apparatus main body M. In addition, a configuration may be adopted in which only a portion of the process unit 9 (for example, the developing unit 20 or the developing container 8) is attachable to and detachable from the apparatus main body M.

[0043] The apparatus body M further includes a scanner unit 10 serving as an exposure unit and a transfer roller 13 serving as a transfer member. The transfer roller 13 abuts against the surface 1a of the photosensitive drum 1, thereby forming a transfer nip N1 serving as a transfer portion therebetween.

[0044] The photosensitive drum 1 serves as an image bearing member for carrying an electrostatic latent image and a developer image. The photosensitive drum 1 is a rotatable photosensitive member formed in a cylindrical shape (drum shape). The photosensitive drum 1 of this example includes an aluminum base formed in a drum shape and a photosensitive layer formed of a negatively charged organic photoconductor on the base. More specifically, the photosensitive drum 1 is a rigid body formed by sequentially applying a resistor layer, a primer layer, and a photosensitive layer on the outer peripheral surface of an aluminum cylinder having a diameter of 24 mm by a dip coating method. The photosensitive layer includes a charge generating layer and a charge transfer layer. The film thickness of the charge transfer layer is, for example, 22 μm. In addition, the photosensitive drum 1 is rotationally driven by a drive motor at a predetermined circumferential speed in the rotation direction indicated by the arrow R around the rotation axis CP. The circumferential speed of the photosensitive drum 1 defines the image forming speed of the image forming device 100 and is also referred to as the process speed.

[0045] The charging roller 2 serving as a charging member contacts the photosensitive drum 1 with a predetermined pressure contact force, thereby forming a charging portion N2. In this example, a configuration is adopted in which there is a certain speed difference between the surface speed of the photosensitive drum 1 and the surface speed of the charging roller 2. The charging roller 2 is charged from the charging voltage applying portion 55a ( Figure 6 ) receives application of a charging voltage as a DC voltage, thereby uniformly charging 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 having the same polarity as the toner.

[0046] The charging roller 2 of this example is a roller member having an outer diameter of 12 mm and including a core metal having a diameter of 6 mm, a base layer formed of alcohol rubber, and a surface layer formed of urethane. In addition, the resistance of the charging roller 2 is 1×10 6 Ω or less, and its hardness measured by the MD-1 rubber durometer is 70°. Note that although DC voltage is used as the charging voltage in this example, the configuration is not limited thereto, and the charging voltage may be a voltage in which AC voltage is superimposed on DC voltage.

[0047] The scanner unit 10 uses a polygonal mirror to irradiate the photosensitive drum 1 with laser light corresponding to image information input from an external device, thereby exposing the surface 1a of the photosensitive drum 1 in a scanning manner. As a result of this exposure, an electrostatic latent image corresponding to the image information is formed on the surface 1a of the photosensitive drum 1. The scanner unit 10 includes a semiconductor laser light source and is capable of emitting laser light with a wavelength of 800 nm and varying the amount of laser light. It should be noted that the scanner unit 10 is not limited to a laser scanner unit and, for example, a light-emitting diode (LED) exposure unit including an LED array having a plurality of LEDs arranged in the longitudinal direction of the photosensitive drum 1 may be employed as the scanner unit 10.

[0048] The developing unit 20 includes a developing container 8 serving as a frame of the developing unit 20, a developing roller 4, and a supply roller 5 that supplies toner to the developing roller 4. The developing container 8 serves as a toner storage portion (developer storage portion) that stores toner serving as a developer. Inside the developing container 8, a storage chamber 8a serving as a space for storing toner and a developing chamber 8b including the developing roller 4 are formed. The developing roller 4 and the supply roller 5 are rotatably supported by the developing container 8. In addition, the developing roller 4 is disposed at the opening portion of the developing container 8 so as to be opposite to the photosensitive drum 1. The supply roller 5 is in contact with the developing roller 4, and the toner contained in the developing container 8 is applied to the surface of the developing roller 4 by the supply roller 5.

[0049] The developing unit 20 of this example adopts a contact developing system as a developing system. That is, the toner layer carried on the developing roller 4 contacts the photosensitive drum 1 at the developing portion N3 where the photosensitive drum 1 and the developing roller 4 are opposed to each other. In other words, the developing roller 4 serving as a developing member forms the developing portion N3 between the developing roller 4 and the photosensitive drum 1. The developing voltage as a DC voltage is applied from the developing voltage applying portion 55b ( Figure 6 ) is applied to the developing roller 4. Under the developing voltage, the toner carried on the developing roller 4 is transferred from the developing roller 4 to the surface 1a according to the potential distribution of the surface 1a of the photosensitive drum 1, so that the electrostatic latent image is developed into a toner image.

[0050] Note that in this example, a reverse development system is employed. That is, the surface of the photosensitive drum 1, which has been charged to a dark potential VD in the charging step, is then illuminated with light in the exposure step to form the toner image. As a result, the surface potential of the exposed area decays to a potential (referred to as the light potential VL) whose absolute value is smaller than the dark potential VD. Simultaneously, 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 toner's normal polarity relative to the light potential VL, and has a polarity opposite to the toner's normal polarity relative to the dark potential VD. Therefore, at the development portion N3, toner adheres from the developing roller 4 to the exposed areas of the photosensitive drum 1, which are areas of the light potential VL, while toner does not adhere from the developing roller 4 to the non-exposed areas, which are areas of the dark potential VD. As a result, the potential distribution on the surface 1a of the photosensitive drum 1 is visualized by the toner, and the electrostatic latent image is developed into a toner image.

[0051] The developing roller 4 of this example is a roller member including a core metal having a diameter of 6 mm and having an overall outer diameter of 15 mm by applying a base layer formed of silicone rubber and a surface layer formed of urethane rubber thereon. The resistance of the developing roller 4 is 1×10 4 Ω or greater and 1×10 12 Ω or less. The supply roller 5 is conductive and is an elastic sponge roller formed by forming a foam layer on the outer peripheral surface of a core metal having a diameter of 6 mm. The resistance of the supply roller 5 is, for example, 1×10 4 Ω or greater and 1×10 8 Ω or less, and the hardness of the supply roller 5 is, for example, 200 gf. Note that the hardness of the supply roller 5 in this example is a value obtained by measuring a load when a flat plate having a longitudinal width of 50 mm is stuck into the surface of the supply roller 5 to a depth of 1 mm.

[0052] The stirring member 7 is provided inside the developing container 8. The stirring member 7 is driven by a motor M1 ( Figure 6 ) is driven to pivot, thereby agitating the toner in the developing container 8 and conveying the toner toward the developing roller 4 and the supply roller 5. In addition, the stirring member 7 has the function of circulating the toner that has not been used for development and has been peeled off from the developing roller 4 in the developing container 8, thereby making the toner in the developing container 8 uniform.

[0053] A developing blade 6 that limits the amount of toner carried on the developing roller 4 is disposed in an opening portion of the developing container 8 in which the developing roller 4 is disposed. The toner supplied to the surface of the developing roller 4 passes through a portion where the developing roller 4 and the developing blade 6 are opposed to each other in accordance with the rotation of the developing roller 4, thereby being formed into a uniform thin layer and charged to a negative polarity by friction charging.

[0054] The developing scraper 6 is, for example, a metal plate having a thickness of 0.1 mm (for example, a metal plate formed of stainless steel (SUS)). One end (fixed end) of the metal plate of the developing scraper 6 is fixed, and the other end (free end) thereof is in contact with the developing roller 4. The developing scraper 6 is arranged so that the direction from the fixed end toward the free end is a direction inclined toward the upstream side in the rotation direction of the developing roller 4 (the opposite direction). The developing scraper 6 used in this example is obtained by performing cutting on the distal end of the SUS metal plate from the side adjacent to the developing roller 4. The distal end portion of the developing scraper 6 is bent in the cutting direction by the cutting.

[0055] The transfer roller 13 serves as a transfer member (transfer unit). The transfer roller 13 includes a core metal having a diameter of 5 mm. In addition, the transfer roller 13 includes a base layer formed of an ion-conductive sponge on the outer peripheral surface of the core metal, so that the total outer diameter of the transfer roller 13 is 12.5 mm. The resistance of the transfer roller 13 is, for example, 4×10 7 Ω, and its hardness measured by Asker C rubber hardness meter manufactured by KOBUNSHIKEIKI CO., LTD. is, for example, 30°.

[0056] When a command to form an image is output to the image forming apparatus 100, a series of operations (image forming operation) for forming an image on the recording material P based on image information input from an external computer, recording medium, etc. connected to the image forming apparatus 100 is started. When the image forming operation is started, the photosensitive drum 1 is driven by a driving source (not shown) and thus operates at a predetermined process speed. Figure 1 The photosensitive drum 1 rotates in the direction of arrow R. In this example, the process speed of the photosensitive drum 1 is 140 mm / sec.

[0057] In the process unit 9, a charge-removing unit 11 that removes electric charge from the photosensitive drum 1 is provided at a position downstream of the transfer nip N1 and upstream of the charging portion N2 in the rotational direction of the photosensitive drum 1. More specifically, the charge-removing unit 11 serving as the charge-removing portion is disposed between the brush member 12 and the charging roller 2 in the rotational direction of the photosensitive drum 1. The charge-removing unit 11 removes the surface potential of the photosensitive drum 1 before reaching the charging portion N2 to induce stable discharge at the charging portion N2.

[0058] The charging roller 2 uniformly charges the surface of the rotating photosensitive drum 1 to a dark potential VD. The scanner unit 10 emits laser light based on input image information toward the photosensitive drum 1. As a result, an electrostatic latent image is formed on the surface 1a of the photosensitive drum 1.

[0059] At the same time, a toner layer charged to a predetermined polarity is formed on the surface of the developing roller 4. Furthermore, as a result of the application of a development voltage to the developing roller 4, the electrostatic latent image on the photosensitive drum 1 is developed at the developing portion N3, thereby forming a toner image on the photosensitive drum 1. In the above-described process, the effective pixel number of the toner image formed by the image forming apparatus 100 according to this example is 400 dpi.

[0060] In parallel with the formation of the above-mentioned toner image, the recording materials P stored in the lower portion of the image forming apparatus 100 are fed one by one. The recording materials P are conveyed to the transfer nip N1 at a timing that matches the timing at which the toner image formed on the photosensitive drum 1 reaches the transfer nip N1. In addition, at a timing that matches the timing at which the toner image formed on the photosensitive drum 1 reaches the transfer nip N1, a transfer voltage is applied from the transfer voltage applying portion 55e ( Figure 6 ) applies a DC transfer voltage to the transfer roller 13. 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. The transfer voltage in this example is set to, for example, +1500V.

[0061] The recording material P to which the toner image has been transferred is conveyed to the fixing unit 14. The fixing unit 14 is a thermal fixing type that fixes the image by heating and melting the toner on the recording material P. The fixing unit 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 is in pressure contact with the fixing film 14a. When the recording material P passes through the nip portion between the fixing film 14a and the pressure roller 14b, the toner image is heated and pressurized. As a result, the toner particles melt and then solidify to adhere to the recording material P, so that the toner image is fixed to the recording material P. The recording material P that has passed through the fixing unit 14 is discharged to the outside of the image forming device 100 by a pair of discharge rollers not shown.

[0062] Image forming apparatus 100 also includes an unillustrated environmental detection unit. This unit is incorporated into image forming apparatus 100 and detects the temperature and humidity of its surroundings. Based on the detection results of the environmental detection unit, the unit controls the voltage applied to the charging roller 2 and developing roller 4, the scanner unit 10, the transfer roller 13, the fixing unit 14, and other components.

[0063] Collection of transfer residual toner

[0064] The following process removes transfer residual toner that remains on the photosensitive drum 1 without being transferred to the recording material P. The surface potential of the photosensitive drum 1 after the transfer step 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 passing through the transfer nip N1. In this example, the surface potential of the photosensitive drum 1 after the transfer step is approximately -150 V.

[0065] After the transfer process, the surface of the photosensitive drum 1 undergoes charge removal by the charge removal unit 11 and moves toward the charging section N2, causing the remaining surface potential to reach 0V. Here, the transfer residual toner is a mixture of toner charged to a positive polarity (the opposite of the normal polarity (in this example, negative polarity) and toner charged to a negative polarity but lacking sufficient charge. After the transfer, the charge of the photosensitive drum 1 is removed by the charge removal unit 11, resulting in a uniform discharge by the charging roller 2, causing the transfer residual toner to be recharged to a negative polarity. The transfer residual toner recharged to a negative polarity in the charging section N2 moves toward the developing section N3 as the photosensitive drum 1 rotates. Furthermore, the surface area of the photosensitive drum 1 that has passed through the charging section N2, while still adhering to the transfer residual toner, is exposed by the scanner unit 10, thereby creating an electrostatic latent image thereon.

[0066] Here, the behavior of transfer residual toner that has reached the development section N3 will be described separately for the exposed and unexposed areas of the photosensitive drum 1. Due to the potential difference between the dark potential VD of the unexposed area of the photosensitive drum 1 and the development voltage, the transfer residual toner adhering to the unexposed area of the photosensitive drum 1 is transferred to the development roller 4 at the development section N3 and collected in the development container 8. This is because the development voltage applied to the development roller 4 is a relatively positive voltage relative to the dark potential VD of the unexposed area. It should be noted that the toner collected in the development container 8 is stirred by the stirring member 7 along with the toner in the development container 8 and, after being carried on the development roller 4, is reused in the development step.

[0067] In contrast, the transfer residual toner adhering to the exposed areas of the photosensitive drum 1 remains on the surface 1a of the photosensitive drum 1 without being transferred from the photosensitive drum 1 to the developing roller 4 at the developing portion N3. This is because the development voltage applied to the developing roller 4 is at a negative potential relative to the light potential VL of the exposed areas. The transfer residual toner remaining on the surface 1a of the photosensitive drum 1 is carried on the photosensitive drum 1 along with other toner transferred from the developing roller 4 to the exposed areas, and moves to the transfer nip N1, where it is transferred onto the recording material P.

[0068] As described above, the process unit 9 of this example is configured to have a cleaner-less configuration (simultaneous development-cleaning configuration) in which transfer residual toner is collected in the developing unit 20 for reuse. As a result of adopting a cleaner-less configuration for the process unit 9, no space is required for installing a collection container for collecting transfer residual toner, etc., thereby further miniaturizing the image forming apparatus 100. Furthermore, by reusing the transfer residual toner, printing costs can be reduced.

[0069] Configuration of developer container and toner pack

[0070] Next, the configurations of the developing container 8 and the toner pack 40 will be described. Figure 2A is a perspective view of the process unit 9 and the toner pack 40, and Figure 2B It is a front view of the process unit 9 and the toner pack 40 . Figure 3A It is along Figure 2B A cross-sectional view taken along line 40A-40A, and Figure 3B It is along Figure 2B A cross-sectional view taken along line 40B-40B.

[0071] like Figures 2A to 3B As shown in FIG. 1 , the developing container 8 includes a storage chamber 8 a that accommodates the stirring member 7. The storage chamber 8 a, which serves as a storage space for storing toner, extends approximately to the total length of the developing container 8 in the longitudinal direction (left-right direction). The inner wall of the storage chamber 8 a is formed integrally with a frame that rotatably supports the developing roller 4 and the supply roller 5. The toner used as the developer to be carried on the developing roller 4 is stored in the storage chamber 8 a.

[0072] In addition, the developing container 8 includes a first protruding portion 37, which serves as a protruding portion 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 protruding portion 38, which protrudes upward from the other end of the storage chamber 8a in the longitudinal direction. A mounting portion 57, to which the toner pack 40 can be attached, is provided at the upper end (distal end) of the first protruding portion 37. A replenishment port 32a for replenishing developer from the toner pack 40 to the storage chamber 8a is provided in the mounting portion 57. The toner pack 40 can be attached to the mounting portion 57 in a state where at least a portion of the toner pack 40, serving as a replenishment container, is exposed to the outside of the image forming apparatus 100.

[0073] The developing container 8 is configured so that the toner supplied through the replenishment port 32a reaches the stirring member 7 only by its weight. Here, "only by its weight" means that a configuration is adopted in which, although no stirring member (conveying member) that rotates or swings to convey the toner is provided between the replenishment port 32a of the developing container 8 and the stirring member 7, the toner reaches the stirring member 7 by its weight. In addition, in the developing container 8, the stirring member 7 is the rotating member closest to the replenishment 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 its rotation.

[0074] The handle portion 39 includes a hook portion 39a that a user can grip by hooking their fingers thereon. The hook portion 39a is formed to protrude upward from the top surface of the handle portion 39. The first protruding portion 37 is formed to have a hollow interior, and the replenishment port 32a is formed in its upper surface. The replenishment port 32a is configured to be coupled to the toner pack 40.

[0075] The toner pack 40 is configured to be attachable to and detachable from the mounting portion 57 of the first protruding portion 37. The toner pack 40 includes a bag body, a shutter member 41 disposed at the opening of the bag body and configured to be openable and closable, and a plurality (in this example, three) of protrusions 42 formed corresponding to the plurality (in this example, three) of recessed portions 32b formed in the mounting portion 57. When replenishing toner to the developing container 8, the user positions the toner pack 40 so that the protrusions 42 pass through the recessed portions 32b of the mounting portion 57 and couples the toner pack 40 to the mounting portion 57. Then, when the toner pack 40 is rotated 180° in this state, the shutter member 41 of the toner pack 40 abuts against an abutting portion (not shown) of the mounting portion 57, thereby rotating relative to the main body of the toner pack 40 and opening. As a result, the toner stored in the toner pack 40 falls from the toner pack 40, and the fallen toner enters the first protruding portion 37 having a hollow interior through the replenishment port 32a. Note that the shutter member 41 may be provided on the replenishment port 32a side.

[0076] The first protruding portion 37 includes an inclined surface 37a ( Figure 3A ). The inclined surface 37a is inclined downward toward the storage chamber 8a. Therefore, the toner supplied through the replenishment port 32a is guided to the storage chamber 8a by the inclined surface 37a. Figure 3A and Figure 3BAs shown in FIG, the stirring member 7 includes a stirring shaft 7a extending in the longitudinal direction, and a scraper portion 7b fixed to the stirring shaft 7a and extending radially outward from the stirring shaft 7a. The scraper portion 7b is a flexible sheet. The stirring member 7 rotates about the stirring shaft 7a. The toner supplied through the replenishment port 32a disposed upstream of the stirring member 7 in the conveying direction is conveyed toward the developing roller 4 and the supply roller 5 by the rotation of the stirring member 7.

[0077] Although in this example Figure 4 and Figure 5A As shown in FIG, the toner pack 40 is made of a plastic bag that is easily deformable, but the configuration is not limited thereto. For example, the toner pack may be made of Figure 5B The bottle container 40B shown in FIG. 1 is formed of a substantially cylindrical shape, or may be formed of a bottle container 40B having a substantially cylindrical shape. Figure 5C , which is formed of paper container 40C shown in the figure. In either case, the toner pack can be made of any material or formed in any shape. Furthermore, as a method of ejecting toner from the toner pack, in the case of toner pack 40 and paper container 40C, squeezing the toner pack with the user's fingers is preferred, and in the case of bottle container 40B, causing the toner to drop from the container while the user vibrates the container by striking it, etc. is preferred. Furthermore, a discharge mechanism may be provided in bottle container 40B to discharge the toner from bottle container 40B. Furthermore, the discharge mechanism may be configured to engage with image forming device 100 and receive a driving force from image forming device 100.

[0078] In addition, the shutter member 41 may be omitted in any of the toner packs, and a sliding shutter member may be employed instead of the rotating shutter member 41. In addition, the shutter member 41 may be configured to be destroyed, for example, by attaching the toner pack to the replenishment port 32a or rotating the toner pack in an attached state, or may have a detachable cover structure such as a sticker.

[0079] Control system for image forming apparatus

[0080] Figure 6 is a block diagram illustrating a control system of the image forming apparatus 100. A controller 90 serving as a control section of the image forming apparatus 100 includes a central processing unit (CPU) 91 serving as a computing device, a random access memory (RAM) 92 serving as a work area for the CPU 91, and a read-only memory (ROM) 93 storing various programs. Furthermore, the controller 90 includes an I / O interface 94 serving as an input / output port for connecting to external devices, and an A / D conversion section 95 that converts analog signals into digital signals.

[0081] The remaining toner sensor 51 and the attachment sensor 53 are connected to the input side of the controller 90. The remaining toner sensor 51 is configured so that its detection signal changes according to the remaining amount of toner in the developing container 8. The remaining toner sensor 51 may be, for example, an optical sensor disposed so that its light path passes through the interior of the developing container 8 and configured so that its detection signal changes when the light path is blocked by the toner struck by the agitating member 7. The attachment sensor 53 detects that the toner pack 40 is attached to the mounting portion 57 (replenishment port 32a) of the developing container 8. For example, the attachment sensor 53 may be a pressure sensor provided at the replenishment port 32a and configured to output a detection signal in response to being pressed by the protrusion 42 of the toner pack 40.

[0082] Furthermore, the controller 90 is connected to an operating section 300, an image forming section 60, and a remaining toner panel 400 serving as a notification member capable of notifying the user of the remaining toner amount. The operating section 300 includes a display section 301 capable of displaying various setting screens, physical keys, and the like. The display section 301 is comprised of, for example, a liquid crystal panel. The image forming section 60 includes a motor M1 serving as a drive source for driving the photosensitive drum 1, the developing roller 4, the supply roller 5, the stirring member 7, and the like. It should be noted that the photosensitive drum 1, the developing roller 4, the supply roller 5, and the stirring member 7 may each be configured to be driven by a different motor.

[0083] The remaining toner panel 400 displays information about the remaining toner in the developing container 8. The remaining toner panel 400 is, for example, one or more lamps, and is controlled so that its lighting state changes step by step based on the detection signal of the remaining toner sensor 51. The user replenishes toner to the developing container 8 by using the toner pack 40 based on the lighting state of the lamp of the remaining toner panel 400 and / or the information displayed on the display portion 301. In addition, the controller 90 controls the outputs of various high-voltage applying circuits (55a to 55e) incorporated in the image forming apparatus 100.

[0084] Latent Image Settings

[0085] Next, the latent image setting of the processing unit 9 in the case of printing a determined pattern to be described later will be described. A charging voltage of -1350 V is applied to the charging roller 2 of this example so that the surface potential (dark potential VD) of the photosensitive drum 1 is -780 V. Then, the scanner unit 10 emits a laser toward the photosensitive drum 1 based on the 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 example, the light amount setting (in this example, 0.35 μJ / cm2) is such that the potential (bright potential VL) of the area (pure black portion) which is a wide area continuously exposed by the scanner unit 10 is -100 V. 2). An electrostatic latent image based on image formation of a determined pattern to be described later is formed by using this light amount setting.

[0086] In contrast, the developing voltage of this example is set to -380 V. In addition, the developing voltage is supplied from the supply voltage applying portion 55c and the blade voltage applying portion 55d ( Figure 6 ) A voltage of -580 V is applied to the supply roller 5 and the developing blade 6 respectively.

[0087] Determine the pattern

[0088] Incidentally, there are cases where image defects may occur due to a mixture of multiple toners within a toner storage unit, for example, when the toner already stored in the toner storage unit of an image forming apparatus is of a different type than the toner newly supplied from a replenishment container such as a toner pack or toner cartridge. In cases where image defects have occurred, it is preferable to provide a determination method for determining whether the image defect is caused by the mixing of multiple toners. Furthermore, in cases where an image defect is caused by the mixing of multiple toners, it is preferable to provide a recovery method for recovering from the image defect using an appropriate method. In this example, a determination method and a recovery method using a pattern image (determination pattern) including a predetermined halftone are proposed.

[0089] The determination pattern used in this example will be described. Figure 7 is a diagram illustrating a determination pattern TP of this example printed on an A4-sized recording material P. In this example, by using the determination pattern TP as will be described later, it is determined whether a plurality of toners having different properties are mixed in the developing container 8. The case where a plurality of toners are mixed in the developing container 8 can be referred to as a different toner mixed state, and the case where a plurality of toners are not mixed in the developing container 8 can be referred to as a different toner non-mixed state.

[0090] The determination pattern TP is a pattern image (test chart) including a plurality of areas (A and B), each of which has a halftone image formed therein. The determination pattern TP of this example includes area A formed with a first dot pattern and area B formed with a second dot pattern. In other words, the determination pattern TP, serving as a pattern image for determination, includes area A serving as a first area in which a halftone image is formed, and area B serving as a second area in which a halftone image is formed with dots having an average dot size smaller than that of the dots in the first area. The first dot pattern and the second dot pattern differ from each other in the average dot size of the dots forming the halftone image (the average value of the number of pixels forming the dots).

[0091] Figure 8A and Figure 8B is a schematic diagram illustrating the dot structure of areas A and B. Figure 8A and Figure 8BIn FIG, each square represented by the dot grid indicates one pixel at 400 dpi. In addition, a color pixel is a pixel (printing pixel) formed by developing with toner.

[0092] In region A, each dot is formed by multiple connected pixels. In this example, each dot in region A has a square shape of 3×3 pixels, resulting in a dot size of 9 pixels. In contrast, in region B, each dot is composed of a single pixel (1×1 pixel). That is, in this example, the dot size of region B is 1 pixel.

[0093] By repetition Figure 8A and Figure 8B The halftone images of regions A and B are formed by a pattern. In addition, the density of the halftone in each region is preferably uniform. The dots are preferably arranged periodically, or as Figure 8A and Figure 8B As illustrated in , it is preferable to adopt a random arrangement in which the intervals between the dots are as constant as possible so that there is no portion where the dots are sparse or dense.

[0094] In this example, the ratio of the number of printed pixels to the total number of pixels in the pattern (image coverage, coverage ratio) is set to 0.136 in area A and to 0.124 in area B. This means that the average inter-dot distance is larger in area A than in area B. In the image forming apparatus 100 of this example, the image coverage of each area is set so that the visual density is approximately equal between area A and area B in different non-mixed states of colorants. This setting is adopted so that the standard for determination by visual observation is clear in the determination process to be described later. It is to be noted that the image coverage is not limited to the above-mentioned image coverage as long as the mixing of different kinds of colorants can be determined. In addition, the image coverage of area A and area B is based on the latent image setting described above, and can also be changed according to the latent image setting of the image forming apparatus to be used, the laser characteristics of the scanner unit, etc.

[0095] In this example, use Figure 7 The determined pattern TP in which the region A and the region B are adjacent to each other is shown in FIG. As a result, a state in which a density difference exists between the region A and the region B can be easily visually recognized. Figure 7 As illustrated in FIG, by using a determination pattern TP in which one area (herein, area A) is sandwiched between another area (herein, area B), visual recognition of density differences can be facilitated. Note that the determination pattern TP in which one of area A and area B is sandwiched between the other area A and area B may be in a form in which the entire periphery of one of area A and area B is surrounded by the other area A and B.

[0096] In this example, the following pattern is used: Area A, having a width of 3 mm in the secondary scanning direction D2, is inserted between two areas B, each having a width of 9 mm in the secondary scanning direction D2. Furthermore, Area A and Area B are each printed to have a width of 50 mm in the main scanning direction D1. A 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 processing unit 9 can form an image). This is because forming the determination pattern TP in the center of the main scanning direction D1, where it is less likely to be affected by various factors of variation, improves the stability of determination.

[0097] Determining the pattern variation

[0098] Note that, although in this example, a pattern in which area A and area B are adjacent to each other and sandwiched between the other is adopted from the viewpoint of visual recognizability, the configuration is not limited thereto as long as determination can be made based on the density difference. For example, the following can be compared: Figure 9 Region A and region B are not adjacent to each other in the recording material P. Alternatively, region A may be printed on a first sheet of recording material P, region B may be printed on a second sheet of recording material P, and the density on the first sheet and the density on the second sheet may be compared. Alternatively, a reference sample serving as a standard density for determination may be prepared, a determination pattern including only region B may be printed on recording material P, and the determination pattern may be compared with the reference sample.

[0099] In addition, although this example describes an example in which regions A and B are each composed of one type of dot, one or both of regions A and B may be composed of multiple types of dots with different dot sizes. For example, region A may be composed of dots with a length of 1 or 2 pixels per side, and region B may be composed of dots with a length of 3 or 4 pixels per side. Furthermore, the dot shape is not limited to the square shape illustrated in FIG8 and may be a variety of shapes. This can be applied as long as the average dot size of region A is larger than the average dot size of region B.

[0100] In addition, in this example, the image coverage PA of region A is set to be equal to or higher than the image coverage PB of region B. In other words, the ratio of pixels forming dots to all pixels in region A (first region) is equal to or higher than the ratio of pixels forming dots to all pixels in region B (second region). In this example, PA is set to 0.136, and PB is set to 0.124. This is because, in region A, the inter-dot distance between dots is large, so the reflection component from the area where there is no toner dispersion around the dots is large, and the printed halftone image is likely to appear brighter (the concentration is likely to be recognized as lower). Therefore, in order to make the visual concentrations of region A and region B equal in different toner non-mixed states, it is preferred that the image coverage PA of region A be set to a value equal to or slightly higher than the image coverage PB of region B (PA ≥ PB). It should be noted that the size relationship between PA and PB may change depending on the latent image setting, the number of effective pixels, etc., and is therefore not limited to this.

[0101] In addition, although the determination pattern TP in which the region A with a large average dot size is sandwiched between the regions B with a small average dot size is used in this example, a determination pattern in which this relationship is reversed may be used.

[0102] Determine the process

[0103] Will refer to Figure 10 The determination process of this example is described. The description will be given under the assumption that this determination process is performed by a service worker. It should be noted that the person who performs this determination process is not limited to the service worker, and the user can perform the determination process.

[0104] First, as an output step (S1), the service worker prints the determination pattern TP. In this example, information about the determination pattern TP is stored in a storage device (ROM 93) within the image forming apparatus 100. Upon receiving an instruction to execute the determination mode, the controller 90 of the image forming apparatus 100 executes an image forming operation based on the determination pattern TP information read from the ROM 93, and prints the determination pattern TP on the recording material P. For example, the determination mode can be executed by displaying an operation screen on a computer connected to the image forming apparatus 100 and clicking an execution button on that screen. Alternatively, the determination mode can be executed by operating a button on the operation unit 300 of the image forming apparatus 100.

[0105] Next, as a comparison step (S2), the concentration DA of area A in the determination pattern TP output on the recording material P is visually compared with the concentration DB of area B. That is, in the comparison step, the concentration of the first area in the pattern image output on the recording material P is compared with the concentration of the second area. Here, although Copy Kid paper (manufactured by UPM, A4 size, grammage: 70g / m2) is used as the recording material in the comparison step of this example, the configuration is not limited to this. In addition, in this example, the concentration comparison of the determination pattern TP is performed in a state where the line of sight of the service worker serving as an observer is orthogonal to the surface of the recording material and the distance between the service worker's eyes and the determination pattern TP on the recording material is about 30cm. It should be noted that this angle and this distance are merely examples of desired observation conditions, and the conditions are not limited to these. In addition, it is preferred that the comparison step be performed in an environment with an illumination of 500 lux or greater, and in this example, the comparison step is performed at about 800 lux. In fact, if the illumination is 30 lux or greater, the determination in the determination step in this example can be performed.

[0106] Next, as a determination step (S3), if the visual comparison result is DA > DB (the density in region A is higher), it is determined that different types of toner are mixed within the developing 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 in the first region is higher than the density in the second region in the comparison step, it is determined that multiple types of toner are mixed within the toner storage portion. Specifically, in this example, if the visual density of the halftone image in the first region is higher than the visual density of the halftone image in the second region, it is determined that multiple types of toner are mixed within the toner storage portion.

[0107] Figure 11 An example of the density relationship and determination result of the determination pattern is illustrated. As described above, in this example, a determination pattern TP in which the region A is disposed at the center and the region A is sandwiched by the regions B from both sides is used. Figure 11 The upper portion of the diagram illustrates a case where the density DA of the region A is higher than the density DB of the region B, and in this case, it is determined in the determination step S3 that different kinds of toners are mixed in the developing container 8 (S3A). Figure 11The middle portion illustrates a case where the concentration DA of region A is approximately equal to the concentration DB of region B, and the lower portion illustrates a case where the concentration DA of region A is lower than the concentration DB of region B, and in these cases, it is determined in the determination step S3 that different kinds of toners are not mixed in the developing container 8 (S3B). The comparison of the concentrations is not limited to being performed by visual observation, and can be performed by measuring the concentration with a densitometer. Considering the workload, etc., determination by visual observation that can be easily determined by service workers and users is preferred. That is, in this example, in the determination step, in a case where it can be visually identified that the concentration of the first region is higher than the concentration of the second region, it is determined that a plurality of toners are mixed in the toner storage portion.

[0108] In response to this determination, the following steps can be performed. If it is determined that different types of toners are mixed, it can be estimated that the cause of the image defect is the mixing of different types of toners, and therefore, for example, the developer container 8 can be replaced. In the event that it is difficult to replace only the developer container 8, the process unit 9 can be replaced. Toner replenishment can be performed to change the ratio of different types of toners mixed in the developer container 8 to recover from the image defect. For example, if the first toner described below is a previously used toner and the second toner is a toner different from the first toner, the developer container 8 can be replenished with the first toner to reduce the ratio of the second toner.

[0109] If it is determined that different types of toners are not mixed, the cause of the image defect is estimated to be other than the mixing of different types of toners, and the search for a different cause is continued. For example, if the cause of the image defect is a damaged component, such as if the photosensitive drum 1 is damaged for some reason, the photosensitive drum 1 is replaced. If the photosensitive drum 1 cannot be replaced alone, the process unit 9 can be replaced.

[0110] Toner

[0111] In order to describe why it is possible to determine whether different types of toners are mixed in the developing container 8 by the above-mentioned determination process, an example of two toners will be described below. The two toners described below are merely examples, and a similar phenomenon may occur when a plurality of toners having different charging properties are mixed in the developing container 8.

[0112] The first colorant is a polymerized colorant, which is a non-magnetic single-component colorant whose normal polarity is negative. The average particle size of the first colorant is 7 μm. As a method for manufacturing the colorant particles, a known method such as a kneading and grinding method or a wet manufacturing method can be used. From the viewpoint of uniformity of particle size and shape controllability, a wet manufacturing method is preferred. In addition, as a wet manufacturing method, a suspension polymerization method, a dissolution suspension method, an emulsion polymerization coagulation method, an emulsion coagulation method, etc. can be used. For the first colorant, a suspension polymerization method is adopted. The core particles of the first colorant are formed of a binder resin containing a styrene-acrylic resin as a main component and have a surface layer containing an organosilicon polymer, and the organosilicon polymer has a structure represented by the following formula (A).

[0113] R-SiO 3 / 2 …(A)

[0114] (wherein R represents a hydrocarbon group having 1 or more and 6 or less carbon atoms.)

[0115] Because the surface layer of the first toner has a negative charging polarity, degradation of charging performance due to long-term use can be suppressed compared to toners without a surface layer. Furthermore, it is preferred that the surface layer containing the organosilicon polymer and the toner core particles be in contact with each other without any gaps therebetween. As a result, oozing caused by resin components, release agents, etc. within the surface layer of the toner particles can be suppressed, resulting in a toner with excellent storage stability, environmental stability, and development durability. Furthermore, external additives may be added to ensure the fluidity of the toner particles and improve their chargeability.

[0116] Similar to the first toner, the second toner is a polymerized toner, a non-magnetic, single-component toner with a negative normal polarity. The average particle size of the second toner is 7 μm. This toner uses externally added inorganic particles, in which inorganic silicon is added to the base particles to ensure fluidity and improve chargeability. The second toner utilizes an emulsion polymerization method. The core particles of the second toner are formed from a binder resin primarily composed of a styrene-acrylic resin and lack a surface layer containing a silicone polymer.

[0117] Although this article describes a toner having a surface layer containing a silicone polymer as an example of the first toner, and a toner without a surface layer containing a silicone polymer as an example of the second toner, any toner can be used as long as the first toner has a higher charging performance than the second toner. The first toner does not necessarily contain a silicone polymer and can have a core-shell structure in which core particles are covered with a surface layer of a different material. According to the determination process of this example, it is possible to determine whether multiple toners containing a first toner and a second toner having a lower charging performance than the first toner are mixed in the developing container 8, regardless of the specific configuration of the toners.

[0118] The "charging performance" mentioned herein indicates the chargeability of toner particles, and for example, the q / d value (charge amount / toner particle size) is used as an indicator thereof. The charging performance of a toner can be defined by the peak of the q / d value measured in a state where a plurality of toners are not mixed.

[0119] A specific example of a method for measuring the charging performance of the toner is as follows. After an image forming operation of outputting a normal (pure white) image is performed by using the image forming apparatus 100 and the processing unit 9 of this example, the toner on the developing roller 4 is collected. The toner collection position on the developing roller 4 is set to a position downstream of the position in contact with the developing blade 6 in the rotation direction of the developing roller 4 and upstream of the developing portion. The charge amount (q / d value) of the collected toner is measured by using an E-SpartAnalyzer manufactured by HOSOKAWA MICRON CORPORATION, and the toner is obtained. Figure 12A distribution.

[0120] exist Figure 12A , the distribution of q / d values obtained in a state where only the first toner is stored in the developing container 8 and the distribution of q / d values obtained in a state where only the second toner is stored in the developing container 8 are plotted on the same graph. Figure 12A As illustrated in FIG, when the peak p1 of the q / d value of the first toner has a larger absolute value than the peak p2 of the q / d value of the second toner, the first toner has higher charging performance than the second toner.

[0121] As a method for making the charging performance of the first colorant higher than the charging performance of the second colorant, for example, in addition to the method of forming the surface layer of the first colorant from an organic silicon polymer, there is also a method of increasing the amount of an external additive having a function of improving the charging performance. In addition, the charging performance can be improved by increasing the amount of a charge control agent dispersed in the binder resin of the first colorant. In addition, as a material for forming the surface of the first colorant, a material can be selected that is positioned on the normal polarity side of the colorant (in this example, the negative polarity side) in the triboelectric electrostatic sequence relative to the material constituting the surface of the second colorant. In addition, in the case of increasing the amount of an external additive that reduces the charging performance of the second colorant (to adjust properties other than the charging performance), or in the case of forming the core particles of the second colorant from a material with lower chargeability, the charging performance of the first colorant is higher than that of the second colorant.

[0122] Furthermore, as in a modified example to be described later, even in the case of toners formed by the same manufacturing method (such as a case where new toner just supplied to the developing container 8 and old toner repeatedly used for image formation are mixed), a similar phenomenon may occur due to differences in charging performance. That is, in this example, the plurality of toners are not limited to toners distinguished by the material of the toner particles, the layer structure of the toner particles, the type and amount of external additives, etc., and may be toners distinguished by changes in the properties of the toner (particularly, charging performance) that have occurred after production.

[0123] Image defects and patterns caused by mixing of different types of toners

[0124] The relationship between the determination pattern and an image defect occurring in a case where the first toner and the second toner are mixed in the developing container will be described.

[0125] The first toner has a surface layer containing an organosilicon polymer having a structure represented by formula (A). Since the surface layer itself is likely to be negatively charged and bonded to the core particles, its charging performance is good and its stability is excellent. In contrast, the second toner does not have a surface layer containing an organosilicon polymer and is therefore inferior to the first toner in terms of charging performance.

[0126] Figure 12A 1 is a conceptual diagram illustrating the distribution of the charge amount (q / d value) of the toner particles carried on the developing roller 4 when only the first toner or only the second toner is present in the developing container 8. In either the case where only the first toner is present in the developing container 8 or the case where only the second toner is present in the developing container 8, only one peak (p1 or p2) exists in the distribution of the charge amount.

[0127] Figure 12BThis is a conceptual diagram illustrating the distribution of the charge amount (q / d value) of the 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, the charge is transferred due to friction between the different types of toners, so the negative charge amount of the first toner increases and the charge amount of the second toner decreases. As a result, the toner particles carried on the developing roller 4 are polarized into a group with a larger charge amount and a group with a smaller charge amount, and as shown in FIG. Figure 12B As illustrated in FIG, two peaks p1′ and p2′ may appear in the distribution of the charge amount of the toner particles.

[0128] The peak p1′ of the group having a larger charge amount is mainly derived from the first toner, but the peak p1′ is increased from the peak p1 ( Figure 12A ) is shifted to the high charge side. The peak p2′ of the group with a smaller charge amount is mainly derived from the second toner, but due to the charge transfer between the first toner and the second toner, the peak p2′ is shifted from the peak p2 ( Figure 12A ) is shifted to the low charge side. Note that, in the case where a plurality of toners having different charging properties are mixed, even if there is no Figure 12B Even in the case of two equally clear peaks p1′ and p2′, the following image defects may occur.

[0129] The second toner whose charge amount has been reduced may be transferred as fog toner to non-exposed areas on the photosensitive drum 1 during development, and may be further transferred from the photosensitive drum 1 to the recording material P. As a result, an image defect (fog image) may occur in which a thin layer of toner adheres to an area on the recording material P where an image is not to be formed.

[0130] In addition, in a cleaner-less configuration as in this example, this fog toner is likely to contaminate the charging roller 2 to cause degradation of charging performance and lower the dark potential VD, which may cause the fog image to be more prominent.

[0131] Next, the relationship between the mixing of different types of toner and the determination pattern will be described. In region A of the determination pattern TP, the dot size is large, and the toner in the surface area of the developing roller 4 corresponding to each dot is substantially completely developed on the photosensitive drum 1. Therefore, in region A, the amount of toner to be developed is unlikely to differ between different toner mixing states and different toner non-mixing states, and therefore, the halftone density is unlikely to be affected by the mixing of different types of toner.

[0132] In contrast, in the area B of the determination pattern TP, the dot size is small, and only the toner in a portion of the surface area of the developing roller 4 corresponding to each dot is transferred to the photosensitive drum 1. Therefore, if in a different toner mixing state, such as Figure 2B As shown in the figure, the charge distribution of the toner is polarized. The more negatively charged first toner is selectively transferred to the photosensitive drum 1 first, and a portion of the second toner with a smaller charge 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 lowered by exposure, remains the same, the total amount of toner transferred to the photosensitive drum 1 in the mixed state with different toners is reduced compared to the unmixed state with different toners, and thus the halftone density in region B is reduced. As a result, in the mixed state with different toners, the density in region B is relatively lower than that in region A.

[0133] As described above, by using the determination pattern TP including a plurality of halftone areas of different dot sizes, the change in the toner charge state caused by the mixing of different types of toner in the developing container 8 can be visualized as the density of the halftone. As a result, in the case where an image defect has occurred, it can be determined whether the image defect has been caused by the mixing of different types of toner.

[0134] Point size of area A and area B

[0135] As described above, in order to visualize the mixture of different types of toner as a density difference in halftones, it is preferable that the dot sizes of region A and region B are each set within an appropriate range. As will be described below, in this example, the halftone image of region A (first region) is composed of dots each having a size of 3×3 pixels or more, and the halftone image of region B (second region) is composed of dots each having a size of 2×2 pixels or less.

[0136] First, if the dot size of the region B is large, the potential (latent image potential) of the surface region of the photosensitive drum 1 corresponding to the dot is lowered to the light potential VL and is less likely to show a difference from the region A. Therefore, the dot size can be set so that the latent image potential of the surface region of the photosensitive drum 1 corresponding to the dot is a value between the development voltage and the light potential VL.

[0137] Specifically, in the image forming apparatus 100 of this example, the latent image potential of an area exposed to light for one pixel or two consecutive pixels is between the development voltage and the light potential VL, while the latent image potential of an area exposed to light for three or more consecutive pixels is reduced to the light potential VL. Therefore, it is preferable to set the dot size of area B within the range of 1×1 to 2×2 pixels. Note that this range includes 1×2 pixels, 2×1 pixels, and 2×2 pixels with one pixel missing.

[0138] When the ratio of 1×1 pixel dots in region B is set higher, it is more likely that the density variation of halftones in a state of mixing different toners will be apparent, and thus, it becomes easier to determine the mixing of different types of toners. However, in an image forming device with a higher resolution than that of this example, because the size of each pixel is smaller, it becomes more difficult to form an appropriate latent image potential. That is, in the case of 1×1 pixel dots, there are cases where the latent image potential is not sufficiently reduced by exposure, and therefore, the halftone image is not developed and the sheet becomes blank, regardless of the presence or absence of different types of toners, and the mixing of different types of toners cannot be determined. Therefore, when using an image forming device with a higher resolution than that of this example, the dot size of region B is preferably set to the number of pixels that achieves an appropriate latent image potential.

[0139] In contrast, in region A, dots of a stable density can be formed by lowering the potential (latent image potential) of the surface area of the photosensitive drum 1 corresponding to the dots to the light potential VL. As described above, when three or more pixels are continuously exposed in the image forming apparatus 100 of this example, the latent image potential is lowered to the light potential VL. Therefore, it is preferable to form dots of 3×3 pixels or more in region A.

[0140] It should be noted that if the size of the dots is excessively increased, the distance between the dots is also increased in order to maintain the concentration relationship with area B, so the dot structure stands out visually and it becomes difficult to determine the concentration. In this example, when the dot size is set to 5×5 pixels or more, the dot structure stands out visually. Therefore, the dot size of area A is preferably set to 4×4 pixels or less. In order to solve such visual problems, small dots can be arranged between large dots to make the gaps less noticeable while increasing the average dot size. It should be noted that the range from 3×3 pixels to 4×4 pixels includes dots obtained by removing any one or more pixels from the 12 pixels in the peripheral portion of the 4×4 pixels.

[0141] Although the image forming apparatus 100 having a resolution of 400 dpi is used in this example, the dot sizes of the regions A and B may vary depending on the resolution of the image forming apparatus. For example, the upper limit of the dot size in the above-mentioned region A (4×4 pixels) is determined based on the visual roughness of the dots printed on the recording material P. 4×4 pixels at 400 dpi corresponds to approximately 0.01×0.01 square inches (0.254×0.254 mm). 2 Therefore, for example, in the case of using the image forming apparatus 100 having a resolution of 600 dpi, the dot size of the area A may be set to be equal to or less than the dot size corresponding to approximately 0.01×0.01 square inches (0.254×0.254 mm).2 ) of 6×6 pixels. In contrast, although the lower and upper limits of the dot size in region B and the lower limit of the dot size in region A are determined mainly based on the relationship with the latent image potential, these can also be changed according to the resolution of the image forming apparatus. For example, the dot size of region B can be set to a size corresponding to 1×1 pixels or more and 2×2 pixels or less in 400 dpi (equal to or greater than 63.5×63.5 μm). 2 and equal to or less than 127×127μm 2 area).

[0142] Modification

[0143] Note that while the example of a mixture of multiple toners produced by different manufacturing methods has been described, a similar situation may occur, for example, when new toner is supplied for replenishment. If there is a significant difference in the charging performance of the toner before and after replenishment, even if the added toners are originally the same, an image defect (fog image) similar to the above-described state of a mixture of the first and second toners may occur. This situation can also be referred to as a state of a mixture of multiple toners. Using the determination method of this example, it is possible to determine whether an image defect has been caused by the mixing of new toner with degraded old toner.

[0144] In addition, although the information of the determination pattern TP is stored in the storage device in the image forming apparatus 100 in this example, the information of the determination pattern TP does not necessarily need to be stored in the image forming apparatus 100. For example, an image file of the determination pattern TP can also be sent from an external device such as a personal computer connected to the image forming apparatus 100 for printing. In addition, if the dedicated determination mode is not set, similar to the case of normal printing, the determination pattern TP can be manually printed by sending the image file of the determination pattern TP to the image forming apparatus 100.

[0145] In addition, although determination is performed by comparing the densities of region A and region B in this example, comparison is not limited to between the two regions. For example, region C may be provided as a third region for dot size between regions A and B, and density comparison may be performed separately between regions A and C or between regions B and C.

[0146] In addition, although the case where the service worker compares the density of the halftones of the region A and the region B by visual observation in the comparison step (S3) has been described in this example, the following operations may be performed to improve the determination accuracy. Figure 11As shown in the figure, determination charges of standard images (sample images, reference images) of three concentration levels including different size relationships between the concentration DA of the halftone of area A and the concentration DB of the halftone of area B are prepared in advance, and a service worker performs a comparison to determine which level of standard image is closest to the determination pattern TP that has been actually output.

[0147] Note that the visual discernibility of the density difference between regions A and B, obtained by actually measuring the determination pattern TP of this example using a densitometer (e.g., Spectral Densitometer 500 Series, Model: 504, manufactured by X-rite), is compared with that observed by eye. In this case, when DA > DB, the density difference is less than 0.01, making the density difference almost impossible to visually discern. Therefore, in this example, when the halftone of region A is denser than that of region B and the density difference is greater than 0.01, it is determined that different types of toner are mixed.

[0148] As described above, the comparison of densities in the determination method of this example is not limited to visual observation and can be performed by comparison with a standard image of a previously prepared determination chart or by density measurement using a densitometer. That is, in addition to visually recognizing the density difference between the first and second areas, it is also possible to determine that a plurality of toners are mixed within the toner storage portion if, in the comparison step, the density of the first area is higher than that of the second area and the difference between the density of the first area and the density of the second area satisfies a predetermined condition.

[0149] In the case of using a determination chart, for example, the predetermined condition is that there is at least one level difference in density level between a standard image having a density closest to the first area and a standard image having a density closest to the second area among a plurality of standard images in the determination chart. In the case of using a densitometer, for example, the predetermined condition is that the difference in the measured density between the first area and the second area, obtained by the aforementioned densitometer manufactured by X-rite (Spectral Densitometer 500 Series, Model: 504), is 0.01 or greater.

[0150] Example 2

[0151] Next, Example 2 will be described. Example 2 has a configuration in which the determination pattern is modified compared to Example 1. In the following description, unless otherwise specified, it is assumed that elements denoted by the same reference symbols as in Example 1 have substantially the same configuration and function as those described in Example 1, and the description will focus on the parts that differ from Example 1. In this example, the fact that there are cases where it is not possible to determine whether different types of toner are mixed using the determination pattern of Example 1 will be described, and a determination method will be described that can correctly determine whether different types of toner are mixed even in such cases.

[0152] Determine the pattern

[0153] Will refer to Figure 13 The determination pattern TP of this example is described. The determination pattern TP of this example has a configuration in which two reference vertical lines L are added to the outside of the pattern of the first example. The two reference vertical lines L are examples of boundary lines indicating the boundary of a predetermined area in the main scanning direction of image formation.

[0154] In this example, a determination pattern TP ( Figure 7 ) are added at positions 60 mm apart on the outside of each of the reference vertical lines L. By using this determination pattern TP, the state of the toner can be determined according to a determination standard different from that of Example 1.

[0155] Determine the process

[0156] Will refer to Figure 14 Describing the determination process of this example: Similar to Example 1, the description will be given assuming that this determination process is performed by a service worker.

[0157] First, as an output step (S11), the service worker prints a determination pattern TP on the recording material P. Next, as a comparison step (S12), the density DA of area A and the density DB of area B in the determination pattern TP output on the recording material P are compared by visual observation. If the comparison result of the visual observation is DA > DB (the density of area A is higher), the process proceeds to the determination step (S14), and it is determined that different types of toner are mixed in the developing container 8 (S14A). In contrast, in cases other than DA > DB, the determination is suspended, and the process proceeds to the print inspection step (S13).

[0158] In the print check step (S13), it is checked whether anything other than the determination pattern is printed inside the two reference vertical lines L relative to the determination pattern TP output on the recording material P. Examples of the thing other than the determination pattern in this example include vertical lines as illustrated in FIG15 . FIG15 illustrates an example of determination in the print check step.

[0159] Next, as a determination step (S14), if Figure 15A As shown in FIG, when there are vertical lines on the inner sides relative to the two reference vertical lines L, it is determined that different kinds of toners are mixed (S14A). That is, in this example, when it is determined in the print checking step that something other than the pattern image is printed in the predetermined area, it is determined that a plurality of toners are mixed in the toner storage portion. Figure 15BIf the vertical line shown in FIG. 1 is outside the two reference vertical lines or if no vertical line exists, it is determined that different types of toners are not mixed (S14B). In this example, if vertical lines exist both inside and outside the two reference vertical lines L, it is determined that different types of toners are mixed (S14A). The response after the determination is the same as in Example 1.

[0160] Although the description is given above with reference to the flowchart, a table to which reference can be made for determination results corresponding to a combination of the results of the concentration comparison step and the print check step as in Table 1 can be prepared in advance, and determination can be made by referring to the table to see to which case the printed determination pattern TP corresponds.

[0161] Table 1

[0162]

[0163] Toner

[0164] In order to describe why it is possible to determine whether different types of toners are mixed in the developing container 8 by using the two reference vertical lines L added in this example, an example of two toners will be described below. The two toners described below are merely examples, and the types of toners are not limited to these as long as the shapes of the toners are different.

[0165] The first toner is the same as that used in Example 1. The third toner is a negatively chargeable, non-magnetic, single-component toner. The core particles of the third toner are formed from a binder resin primarily composed of a styrene-acrylic resin and have an average particle size of 10 μm. This toner is manufactured using a method in which raw materials are mixed, melted, cooled, and solidified, followed by pulverization and surface treatment in a mechanical pulverizer while the temperature is adjusted. The third toner uses externally added inorganic particles, obtained by externally adding inorganic silicon to the base particles to ensure fluidity and improve chargeability.

[0166] Due to the manufacturing method of powdered toners, the particle size of the third toner, a powdered toner, varies significantly compared to the first toner, a polymerized toner, and the upper limit of the particle size distribution is more likely to be greater than the difference in average particle size. Furthermore, while the average circularity of the first toner is approximately 0.99, the average circularity of the third toner in this example is approximately 0.92, and the third toner includes large, non-uniformly shaped particles. It should be noted that even between polymerized toners and powdered toners, circularity may vary due to differences in manufacturing methods, and as will be described later, toners with low circularity may be fused to the developing blade 6.

[0167] The average circularity in this example is used as a simple quantitative representation of the particle shape and is calculated by the following method. First, the particle shape of the toner particles is measured by using a flow-type particle image analyzer FPIA-2100 manufactured by TOA MEDICAL ELECTRONICS Co., Ltd., and the circularity is obtained by the following formula (1).

[0168] Ci=Pi / Qi...(1)

[0169] In formula (1), Ci represents the circularity of the i-th toner particle, Pi represents the circumference of a circle having the same area as the projected image of the i-th toner particle, and Qi represents the circumference of the projected image of the i-th toner particle.

[0170] Furthermore, as represented by the following formula (2), a value (C-bar) obtained by dividing the sum of the circularities of all the measured particles by the total number (m) of the measured particles is defined as the average circularity.

[0171]

[0172] Image defects and patterns caused by mixing of different types of toners

[0173] The relationship between the determination pattern and an image defect occurring in a case where the first toner and the third toner are mixed in the developing container 8 will be described.

[0174] First, we will describe image defects caused by the third toner. Due to its manufacturing method, the third toner has a large particle size and an uneven shape. Therefore, when the toner supplied to the developing roller 4 passes through the portion where the developing roller 4 faces the developing blade 6, a portion of the toner is engaged (strongly pressed) by the developing blade 6 and melts to the developing blade 6. In this melted portion, the developing blade 6 cannot fully charge the toner on the developing roller 4, resulting in a foggy image with vertical black streaks, as illustrated in Figure 15.

[0175] In particular, in the cleaner-less configuration of this example, the misted toner of the vertical black streaks may contaminate the charging roller 2 , and thus the image defect of the vertical black streaks may be more noticeable.

[0176] Here, although continuous vertical black streaks are illustrated in FIG. 15 , an image defect that appears as a discontinuous vertical dotted line in the sub-scanning direction D2 may occur at a period corresponding to each rotation of the charging roller 2. In the above-described determination flow, such vertical black streaks are regarded as vertical streaks for determining whether different types of toner are mixed, and determination is made in the print inspection step.

[0177] Next, we will describe the characteristics of vertical black streaks that appear when a first toner and a third toner are mixed. Although the toner mixed with the third toner is the first toner in this article, the configuration is not limited to this, as long as the toner is a polymerized toner with a uniform particle size. As described in Example 1, the first toner includes a surface layer containing a silicone polymer and has good charging properties and excellent stability. In contrast, the third toner has an uneven shape due to its manufacturing method and has lower charging properties than the second toner of Example 1. In the case of a large difference in charging properties, when the toners mixed in the developer container 8 are supplied from the supply roller 5 to the developer roller 4, the first toner is selectively used electrostatically for development and is consumed earlier. Then, when the remaining amount of the first toner in the developer container 8 is small, the third toner begins to be supplied to the developer roller 4 at a high rate.

[0178] As described above, in the case of the toner combination as in this example, even if different kinds of toners are mixed in the developing container 8, one kind of toner selectively coats the developing roller 4. Figure 12B The state in which different kinds of toners coexist on the developing roller 4 illustrated in FIG. 1 is temporary, and there are cases in which mixing of different kinds of toners cannot be determined by using the determination pattern TP of Example 1.

[0179] When the third toner begins to be supplied to the developing roller 4, vertical black streaks begin to appear, as described above. At this point, vertical black streaks begin to appear within the maximum area (image area) in the main scanning direction D1 where the developing roller 4 can develop a toner image. The reason for this is as follows.

[0180] While toner is consumed in the image area during toner image development, virtually no toner is consumed in the non-image area located at the end portion and including at least the margin. Therefore, the toner supplied to the developing roller 4 transitions from the first toner to the third toner in the image area as toner consumption increases, but the first toner remains in the non-image area on the developing roller 4. This means that image defects caused by toner seizure are more likely to occur in the image area than in the non-image area, and they occur when toner is mixed in.

[0181] Note that vertical black streaks are less likely to appear in non-image areas than in image areas, but this does not mean that vertical black streaks never appear in non-image areas. Therefore, in the above-described determination process, the presence of vertical black streaks both inside and outside the two reference vertical lines L is determined to indicate a mixture of different toner types. Note that the determination method is not limited to this, and, while considering the likelihood of vertical black streaks appearing, the determination can be made based on the ratio of vertical black streaks between inside and outside the two reference vertical lines L. Furthermore, if vertical black streaks already appear outside the two reference vertical lines L, it can be determined that different toner types are not mixed, regardless of the presence or absence of vertical black streaks inside the two reference vertical lines L.

[0182] In this example, the two reference vertical lines L are printed slightly inward relative to the boundary between the non-image area (margin) and the image area. In other words, the predetermined area indicated by the boundary lines (reference vertical lines L) of the pattern image is included within the maximum area in the main scanning direction where the image forming device can form an image. Therefore, the presence or absence of image defects (vertical black streaks) inward relative to the two reference vertical lines L can be used to determine whether the image defect is caused by mixing of different types of toner.

[0183] In this example, the positions of the two reference vertical lines L are set to be slightly inside the non-image area and the image area, taking into account the fact that a portion of the first toner remaining in the non-image area of the developing container 8 flows into the image area. The configuration is not limited to this, and for example, the two reference vertical lines L may be formed at the boundary position between the non-image area and the image area.

[0184] In addition, although in this example, the boundary of the occurrence area of the image defect (vertical black streak) is represented by two reference vertical lines L, the configuration is not limited to this. Figure 16 As illustrated in FIG, determination can be performed by performing a print check step in the determination area using a pattern including a determination area enclosed by a quadrilateral having two sides at the same positions as two reference vertical lines L. Furthermore, determination does not necessarily require two reference vertical lines L, and a service worker can perform the print check step inside the position serving as a boundary by using a ruler. It is more preferable to print reference vertical lines L or a substitute thereof in the determination pattern to facilitate the determination step by the service worker.

[0185] As described above, according to the present example, even in a case where whether or not different kinds of toners are mixed cannot be correctly determined by using the determination pattern of Example 1, mixing of different kinds of toners can be determined more appropriately.

[0186] Example 3

[0187] Next, Example 3 will be described. Example 3 has a configuration in which the determination process of Example 2 is changed. In the following description, it is assumed that elements denoted by the same reference symbols as those in Example 2 have substantially the same configuration and function as those described in Example 2, and portions different from Example 2 will be mainly described.

[0188] Preparatory Operations

[0189] In this example, in order to improve the accuracy of determination using the determination pattern TP, the determination pattern TP is printed on two sheets of the recording material P. Also, in this example, a step of performing a preliminary operation is provided between printing on the first sheet and printing on the second sheet.

[0190] The reason for performing the preliminary operation in this example will be described. Since the determination pattern TP of Example 1 is mainly used to determine the state of the colorant in the developer container 8 based solely on the concentration difference of the halftone, determination may be difficult when the surface potential of the photosensitive drum 1 changes due to secondary factors as described below. For example, since the image forming apparatus 100 of this example has a cleaner-less configuration, a portion of the atomized colorant attached to the non-exposed area on the photosensitive drum 1 adheres to the charging roller 2. Under conditions where a large amount of atomized colorant is generated, the amount of colorant attached to the charging roller 2 also increases, so the charging performance changes, and the dark potential VD also changes. If the dark potential VD is further on the negative side, the overall concentration of the halftone becomes lower, and in particular, because the dot size of area B of the determination pattern TP is small, its concentration may be low. Therefore, even if different types of colorants are not actually mixed in the developer container 8, it is possible to erroneously determine that different types of colorants are mixed.

[0191] This phenomenon is likely to occur in high-humidity environments. In particular, under conditions such as the first thing in the morning when a user begins using image forming apparatus 100, the charge in the toner in developer container 8 has decayed due to the influence of moisture in the air, and more fogged toner may appear. Therefore, in this example, the following preliminary operation is performed to improve the accuracy of determination.

[0192] The preparatory operation of this example is an operation of removing fogged toner by cleaning the charging roller 2 while the developing roller 4 is rotationally driven, and is constituted by a combination of the following two operations.

[0193] The first operation will be described. In the first operation, the charging roller 2, the transfer roller 13, and the developing roller 4 are idling (rotationally driven without forming an image) by applying -600V to the charging roller 2 and the transfer roller 13 and +150V to the developing roller 4. At this time, the surface potential of the photosensitive drum 1 is about -50V. By applying a voltage of positive polarity to the developing roller 4, this operation suppresses the occurrence of atomized colorant caused by a charging failure on the charging roller 2. In addition, through this operation, the polarity of the colorant attached to the charging roller 2 is changed to negative polarity by friction due to the difference in circumferential speed between the charging roller 2 and the photosensitive drum 1, and the colorant whose polarity has been changed to negative polarity is discharged onto the photosensitive drum 1 by the potential difference. The colorant discharged onto the photosensitive drum 1 is collected by the developing roller 4 in the developing section.

[0194] As described above, in the first operation, when a voltage having the same polarity as the normal polarity of the toner is applied to the charging roller 2 and a voltage having a polarity opposite to the normal polarity of the toner is applied to the developing roller 4, the charging roller 2 and the photosensitive drum 1 rotate to rub each other.

[0195] Next, the second operation will be described. In this second operation, while the developing roller 4 is idled by applying a voltage of +150V to it, the voltage applied to the charging roller 2 is switched between ON and OFF at a predetermined cycle. In this example, the voltage applied in the ON state is set to -900V, and the ON and OFF states are repeatedly switched at intervals of 900ms, which is equal to or longer than the time corresponding to one rotation of the photosensitive drum, to establish a surface potential corresponding to one rotation of the photosensitive drum. At this time, the surface potential of the photosensitive drum 1 is approximately -350V, and by switching the voltage application to the charging roller 2 ON and OFF, the toner adhered to the charging roller 2 is discharged onto the photosensitive drum 1. Furthermore, while this example employs an operation in which the voltage application to the charging roller 2 is switched ON and OFF, the voltage application does not necessarily need to be turned OFF, and toner with the same polarity as in the OFF state can be discharged onto the photosensitive drum as long as the applied voltage is further positive than -350V.

[0196] As described above, in the second operation, the photosensitive drum 1 rotates while 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 2, and applying a voltage having a polarity opposite to the normal polarity of the toner to the developing roller 4.

[0197] In this example, the preliminary operation, including the first and second operations, is performed for approximately 80 seconds. As a result of this preliminary operation, even in the early morning, in a high-humidity environment where the toner charge has decayed, the toner charge is increased, suppressing the accumulation of toner fog. This allows the charging roller 2 to be cleaned, even if fogged toner is attached. As a result, changes in the surface potential of the photosensitive drum 1 due to secondary factors are suppressed, and the halftone density of area B of the determination pattern TP more appropriately reflects the state of the toner in the developer container 8. Consequently, a more appropriate determination can be made in the comparison step.

[0198] Furthermore, as described in Example 2, the vertical streaks detected in the print check step of Example 2 are printed due to a charging failure of the charging roller 2. Therefore, there is a tendency for the level of vertical streaks to improve after the preparatory operation compared to the level before the preparatory operation. Examples of indicators of the level of vertical streaks include their width, number, and density, with a greater width, greater number, and higher density corresponding to a worse level. Therefore, the print check step is performed only on the first sheet using the determination pattern TP, thereby determining whether different types of toner are mixed.

[0199] Examples of methods for executing the preliminary operation include a method of displaying an operation screen for executing the preliminary operation on a display of a computer connected to the image forming apparatus 100 and clicking an execution button. Furthermore, examples of methods for executing the preliminary operation include a method of operating a button displayed on a screen of the operation section 300 of the image forming apparatus 100.

[0200] Determine the process

[0201] Will refer to Figure 17 Describing the determination process of this example: Similar to Example 1, the description will be given assuming that this determination process is performed by a service worker.

[0202] First, as a first output step (S21), the service worker causes the image forming apparatus 100 to execute the determination mode, thereby printing a determination pattern TP similar to the determination pattern in Example 2 on the recording material P. The determination pattern TP outputted at this time is the determination pattern on the first sheet. The execution method of the determination mode is similar to that of Example 1. That is, in the first output step, the image forming apparatus 100 outputs a first pattern image on the first recording material, the first pattern image including a boundary line indicating the boundary of a predetermined area in the main scanning direction of image formation.

[0203] Next, as a first print inspection step (S22, first inspection step), a check is performed to determine whether vertical streaks exist within the two reference vertical lines L of the determination pattern relative to the first sheet. If vertical streaks exist within the two reference vertical lines L in S22, the process proceeds to a determination step S27 (different toner mixing determination step), and a determination is made that different types of toners are mixed (S27A). If vertical streaks do not exist within the two reference vertical lines L in S22, the process proceeds to a preparatory operation execution step (S23).

[0204] Next, in the preparatory operation execution step (S23), the image forming apparatus 100 performs a preparatory operation. Once the preparatory operation is complete, the image forming apparatus 100 executes the determination mode as a second output step (S24) to print a determination pattern TP similar to the determination pattern in Example 2 on the recording material P. The determination pattern TP outputted this time is the determination pattern on the second sheet. That is, in the second output step, after the preparatory operation, the image forming apparatus 100 outputs a second pattern image on the second recording material. This second pattern image includes a first area formed with a halftone image and a second area composed of dots having a smaller average dot size than the first area.

[0205] Next, as a comparison step (S25), the density DA of area A and the density DB of area B in the determination pattern TP of the second sheet are visually compared. At this point, as a determination step (S27), if DA > DB (the density of area A is higher), it is determined that different types of toner are mixed (S27A). In contrast, in other cases other than DA > DB, the process proceeds to the second print inspection step (S26, the second inspection step), and to determine the determination pattern TP of the second sheet, a check is performed similar to Example 2 to determine whether vertical streaks exist within the two reference vertical lines L relative to the determination pattern. If no vertical streaks exist within the two reference vertical lines L in S26, the process proceeds to the determination step (S27), and it is determined that different types of toner are not mixed (S27B). In contrast, if vertical streaks exist within the two reference vertical lines L in S26, the process proceeds to the determination step (S27), and it is determined that different types of toner are mixed (S27A). The same processing as in Example 1 can be performed after the determination.

[0206] The above-described determination flow is the same as the determination made by preparing in advance a table such as Table 2 that can be referred to for determination results corresponding to combinations of the results of the density comparison step and the print comparison step, and referring to the table to determine to which case in Table 2 the determination patterns TP on the first and second sheets correspond. Figure 17Any of a method of making determinations sequentially according to the flowchart of Table 2 and a method of making determinations according to a determination table such as Table 2.

[0207] Table 2

[0208]

[0209]

[0210] By performing the preliminary operation steps in the above-described determination flow, contamination of the charging roller 2 by fog toner can be reduced, and thus the accuracy of determination of mixing of different kinds of toners based on the density difference of halftones can be improved.

[0211] Please note that Figure 17 In the case of the determination process described in Example 2, areas A and B in the determination pattern TP for the first sheet are not used for determination. Therefore, the determination pattern TP for the first sheet can be a pattern printed with only the two reference vertical lines L added in Example 2. Furthermore, since the purpose of the preliminary operation is to improve the accuracy of density comparison and improve the problem of vertical black streaks, determination regarding the mixing of different types of toner can also be performed by executing only the comparison step S25 without executing the second print inspection step S26. Therefore, the determination pattern TP of Example 1, which does not include the reference lines L, can be used as the determination pattern TP for the second sheet.

[0212] As described above, by executing the determination flow of this example, it is possible to improve the accuracy of the determination of whether or not different kinds of toners are mixed in the developing container 8 .

[0213] It should be noted that although the preparatory operation is performed for approximately 80 seconds in this example, the execution time of the preparatory operation can be changed according to the detection results of temperature and humidity in the environmental detection section. For example, by adopting a longer execution time for the preparatory operation for higher humidity, it is possible to improve the determination accuracy with the minimum necessary time according to the environment at the time of determination.

[0214] In addition, although the determination flow in this example employs a preparatory operation performed between the printing of the determination pattern TP on two sheets, the determination flow of Example 1 may also print the determination pattern TP after the preparatory operation is performed. As a result, the determination accuracy can also be improved in the determination method of Example 1.

[0215] Modification

[0216] In Example 3, the print inspection steps (S22, S26) are performed for each of the first sheet and the second sheet, and in the case where vertical streaks are present on the inner side relative to the reference vertical line L on at least one of the first sheet and the second sheet, it is determined that different types of toners are mixed. Meanwhile, as described above, there is a tendency that the level of vertical streaks generated by the mixing of different types of toners changes between before and after the preparatory operation. Therefore, as described above, Figure 18 In the determination flow illustrated in FIG, the levels of vertical streaks between the determination patterns TP of the first sheet and the second sheet may be compared.

[0217] The first output step S31, the preparatory operation execution step S32, the second output step S33 and the comparison step S34 in this modification are respectively Figure 17 The first output step S21, preparatory operation execution step S23, second output step S24, and comparison step S25 of Example 2 illustrated in FIG are identical. In contrast, in this modified example, if vertical streaks are present in the determination pattern TP of the first sheet, inward from the reference vertical line L (S35: Yes), and the level of vertical streaks in the determination pattern TP of the second sheet is improved compared to the first sheet (S36: Yes), it is determined that different types of toner are mixed. If vertical streaks are not present in the determination pattern TP of the first sheet, inward from the reference vertical line L (S35: Yes), it is determined that different types of toner are not mixed, regardless of the level of vertical streaks in the determination pattern TP of the second sheet. Furthermore, even if vertical streaks are present in the determination pattern TP of the first sheet, inward from the reference vertical line L (S35: Yes), if the level of vertical streaks in the determination pattern TP of the second sheet is not improved compared to the first sheet (S36: No), it is determined that different types of toner are not mixed.

[0218] As described above, in this example, determination regarding the mixing of different kinds of toner is made based on a change in the level of vertical streaks between before and after the preparatory operation step is performed. That is, when the level of images other than the pattern image generated in the predetermined area when the pattern image is output after the preparatory operation step is improved compared to the level of images other than the pattern image generated in the predetermined area when the pattern image is output before the preparatory operation step is performed, it is determined that different kinds of toner are mixed within the toner storage portion.

[0219] As a result, determination regarding the mixing of different kinds of toners can be made more accurately based on the generation mechanism of vertical streaks.

[0220] The determination flow of this example is the same as the determination performed by preparing a determination table such as Table 3 shown below in advance and referring to the table to determine which case the determination pattern TP on the first sheet and the second sheet corresponds to. "-" in the table indicates that the determination result of the right column is applied regardless of whether the result of the corresponding entry is "yes" or "no". Figure 18 Any of a method of performing determination sequentially according to the flowchart of Table 3 and a method of performing determination according to a determination table such as Table 3.

[0221] Table 3

[0222]

[0223] Example 4

[0224] Next, Example 4 will be described. In Example 4, a series of processes (restoration process) will be described in which a step for restoring from an image defect is selectively performed in addition to the determination process described in Example 1. In the following description, it is assumed that elements denoted by the same reference symbols as in Example 1 have substantially the same configuration and function as those described in Example 1, and portions different from Example 1 will be mainly described.

[0225] In this example, the process unit 9 is configured to be attachable to and detachable from the apparatus main body M, and a service worker can replace the process unit 9. Note that the process unit 9 includes the photosensitive drum 1, the charging roller 2, the developing unit 20, the charge removal unit 11, and the brush member 12, and members unrelated to the cause of the image defect can be replaced together as part of the process unit 9. Therefore, it is preferable that the frequency of replacement of the process unit 9 be the minimum necessary.

[0226] Recovery Process

[0227] Will refer to Figure 19 The flow of this example is described. The description is given assuming that this flow is executed by a service worker. Note that the person who executes this determination flow is not limited to a service worker, and a user can execute this flow.

[0228] First, as an output step (S1), the service worker prints a determination pattern TP. Next, as a comparison step (S2), the density DA of area A and the density DB of area B in the determination pattern TP output on the recording material P are visually compared. That is, in the comparison step (S2), the density of the first area and the density of the second area in the pattern image output on the recording material P are compared. Up to this point, the process is the same as in Example 1.

[0229] Next, in the case where the comparison result in the comparison step (S2) is DA>DB (the density of the area A is higher), as a recovery step (R3), the service worker attaches a new toner pack 40 to the mounting portion 57 and performs toner replenishment (R3A). That is, in the case where it is determined in Example 1 that different kinds of toners are mixed in the developing container 8 (S2: Figure 10 ), toner replenishment (R3A, replenishment step) is executed as the recovery step (R3) in this example.

[0230] In the case where the comparison result in the comparison step (S2) is not DA>DB (the density of region B is higher or approximately the same), the service worker replaces the process unit 9 (R3B). That is, in the case where it is determined in Example 1 that different kinds of toners are not mixed in the developing container 8 (S2: Figure 10 , in this example, as a recovery step (R3), the processing unit 9 is replaced (R3B, a replacement step).

[0231] Recovering from image defects by toner replenishment

[0232] The reason why the image defect can be recovered by replenishing toner in the case where the comparison result in the comparison step ( S2 ) is DA>DB will be described.

[0233] As described in Example 1, in the case where a plurality of toners having different charging properties are mixed in the developing container 8, the toner having the lower charging property (second toner) may cause an image defect (fog image). In addition, as described in Example 1, the mixing of different kinds of toners having different charging properties in the developing container 8 can be visualized as a density difference between the region A and the region B in the determination pattern TP.

[0234] It will be considered that an image defect has occurred due to the mixing of the first toner and the second toner in the developing container 8 and the Figure 19 In this case, the comparison result in the comparison step (S2) is DA>DB (the density of region A is higher), and as the recovery step (R3), the toner is replenished to the developing container 8 by using the toner pack 40 (R3A). As described below, the replenished toner may be the first toner or the second toner.

[0235] First, the case of replenishing the first toner in the recovery step (R3) will be described. When the first toner is supplied, the proportion of the first toner in the total toner in the developing container 8 increases. In addition, the proportion of the first toner in the toner carried on the developing roller 4 increases, and the proportion of the second toner, which may become fogged toner, decreases. Therefore, by replenishing the first toner, fogged toner can be reduced, and recovery from image defects (foggy images) can be achieved at least partially.

[0236] Next, the case where the second colorant is replenished in the recovery step (R3) will be described. When the second colorant is replenished, the ratio of the second colorant in all the toners in the developing container 8 increases. In addition, the ratio of the second colorant in the toner carried on the developing roller 4 increases, while the ratio of the first colorant decreases. In this case, for each toner particle of the second colorant, the chance of transfer of the charge of the toner particles in and out of the first colorant is reduced. As a result, the ratio of the toner with a small charge amount that is likely to become atomized toner is reduced. In other words, when Figure 12B When the second toner is replenished in the state of , the peak p2′ on the side with a smaller charge amount shifts toward the negative polarity side (high charge side), and the ratio of toner particles having a charge amount closer to 0 decreases. Therefore, by replenishing the second toner, fogged toner can be reduced as a result, and recovery from image defects (foggy images) can be achieved at least partially.

[0237] Overview of this example

[0238] As described above, in this example, when an image defect has occurred and it can be determined that the image defect is caused by the mixing of different types of toner, replenishment with new toner (R3A) is performed as a recovery step (R3). In other words, similar to Example 1, in the case where it can be 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 an illumination of 30 lux or greater, the replenishment step (R3A) of replenishing the developing container 8 (toner storage portion) with toner is performed. As a result, recovery from an image defect (foggy image) caused by the mixing of different types of toner can be achieved.

[0239] That is, according to this example, a recovery method can be provided that can achieve recovery from image defects caused by mixing of multiple toners. In addition, recovery from image defects can be achieved without replacing the process unit 9, which is a common way to solve the occurrence of image defects.

[0240] Note that the comparison method in the comparison step (S2) is not limited to visual observation as described in Example 1, and can be performed by comparison with a standard image of a pre-prepared determination chart or by density measurement using a densitometer. That is, if the density DA of region A (first region) is higher than the density DB of region B (second region) in the comparison step (S2), and the difference between density DA and density DB satisfies a predetermined condition, the replenishment step (R3A) can be performed. As a result, the apparatus can recover from image defects (foggy images) caused by the mixing of different types of toner.

[0241] Furthermore, according to this example, 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 the recovery step (R3). In other words, if it cannot be 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), the replacement step (R3B) of replacing at least a portion of the image forming mechanism included in the image forming apparatus 100 is performed. As a result, recovery from image defects caused by causes other than the mixing of different types of toner can be achieved.

[0242] Modification

[0243] Although the processing unit 9 is replaced in the comparison step (S2) in cases other than DA>DB, the object of replacement in the replacement step (R3B) can be changed according to the specific configuration of the image forming apparatus 100. That is, in the replacement step (R3B), recovery from the image defect can be attempted by replacing at least a part of the image forming mechanism included in the image forming apparatus 100 in a unit different from the processing unit 9. The "image forming mechanism" is a collection of devices, units, and components for performing any step of the electrophotographic process. The image forming mechanism in this example includes the processing unit 9, the scanner unit 10, the transfer roller 13, and the fixing unit 14. For example, in a case where the developing unit 20 can be attached to and detached from the apparatus main body M independently of the other units, in a case other than DA>DB in the comparison step (S2), only the developing unit 20 can be replaced. In addition, in a case where a component that is the cause of the image defect can be confirmed, only that component (for example, only the photosensitive drum 1 or only the charging roller 2) can be replaced.

[0244] In addition, in cases other than DA>DB in the comparison step (S2), that is, when it cannot be determined that the cause of the image defect is the mixing of different types of toners and the cause of the image defect can be confirmed, measures other than the replacement step (S3B) can be taken according to the cause. For example, if dirt on the surface of the photosensitive drum 1 is the cause of the image defect and the dirt can be removed by cleaning, the service worker can clean the photosensitive drum 1.

[0245] In addition, depending on the toner mixing ratio when the image defect occurs, there may be a case where the image defect cannot be fully recovered by only one cycle of toner replenishment. In this case, further recovery from the image defect can be achieved by resupplying the same type of toner to increase the ratio of the same type of toner in the developing container 8.

[0246] In addition, although either the first toner or the second toner can be replenished in the recovery step (R3) in this example, it is more preferable to replenish the first toner in view of the sustainability of the effect of suppressing image defects. This is because, when the degradation of the toner progresses during repeated image forming operations after toner replenishment, image defects (fog images) are more likely to occur when the ratio of the second toner in the developing container 8 is high. In contrast, when the first toner is replenished in the recovery step (R3), even if the degradation of the toner has progressed and its charging performance has decreased to a certain extent, the ratio of toner particles with a charge amount close to zero, which is likely to become fogged toner, is less likely to increase, and therefore image defects (fog images) are relatively less likely to occur.

[0247] In addition, although the toner is replenished immediately in the case of DA>DB in the comparison step (S2) in this example, the toner replenishment may be performed after the toner amount in the developer container 8 is reduced in the case of DA>DB in the comparison step (S2). Examples of methods for reducing the toner amount in the developer container 8 include a physical method of disassembling and turning over the processing unit 9 to drop the toner from the replenishment port 32a. In addition, the method for reducing the toner amount in the developer container 8 may be a method of continuously performing printing with a high image coverage (for example, a solid image with a density of 100%). By performing toner replenishment after reducing the toner amount in the developer container 8, the mixing ratio of different kinds of toners is reduced, and image defects can be further improved in some cases.

[0248] Modifications related to the locking mechanism

[0249] Incidentally, in an image forming apparatus of a toner replenishment type in which toner is replenished from the outside by using a toner pack 40 (replenishment container) as in this example, a lock mechanism 57L ( Figure 1 When the lock mechanism 57L is in the locked state, toner replenishment by the user is restricted, and when the lock mechanism 57L is in the unlocked state, toner replenishment by the user is permitted. The controller 90 sets the lock mechanism 57L to the locked state based on the detection signal of the toner remaining amount sensor 51 until the toner remaining amount in the developing container 8 is equal to or less than a predetermined amount, and sets the lock mechanism 57L to the unlocked state when the toner remaining amount is equal to or less than the predetermined amount.

[0250] For example, the locking mechanism 57L includes a locking member and an actuator, such as a solenoid, that moves the locking member to 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 permits rotation of the toner pack 40. Another example of the locking mechanism 57L includes a cover member that is movable 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 opening and closing of the cover member. This is merely an example, and any form may be employed as long as the locking mechanism 57L can assume a locked state that restricts toner replenishment and a released state that permits toner replenishment.

[0251] In the case of the image forming apparatus 100 including the lock mechanism 57L, there are cases where it is necessary to perform toner replenishment to recover from an image defect regardless of the remaining toner amount in the developing container 8. Therefore, as a modified example, an image forming apparatus 100 having a function of setting the lock mechanism 57L to the unlocked state regardless of the remaining toner amount in the developing container 8 will be described.

[0252] Figure 20 4 is a flowchart illustrating the recovery process related to this modification. Figure 19 ), this process differs in that the lock release step (R1) is executed when the comparison result in the comparison step (S2) is DA > DB (the concentration in region A is higher). In other words, in this example, the lock release step (R1) is executed when the replenishment step (R3A) is executed.

[0253] In the lock release step (R1), the service worker instructs the image forming apparatus 100 to set the locking mechanism 57L to the lock release state. For example, the method for instructing the image forming apparatus 100 may be a method of displaying an operation screen on a display of a computer connected to the image forming apparatus 100 and clicking a lock release button on the screen. In addition, the method for instructing the image forming apparatus 100 may be a button operation on the operation screen of the operation portion 300 of the image forming apparatus 100. Note that the lock release of the locking mechanism 57L may be performed at any stage of the process (for example, it may be performed before the comparison step (S2)) as long as the stage is before the toner replenishment (R3A). In addition, in the case of Figure 20 In the figure, when the lock release (R1) is executed after the comparison step (S2) and the comparison result of the comparison step (S2) is different from DA>DB, the lock release of the lock mechanism 57L is not necessarily executed.

[0254] According to this modification, when an image defect caused by a mixture of different types of toners occurs in the image forming apparatus 100 including the lock mechanism 57L, recovery from the image defect can be achieved by toner replenishment.

[0255] Modifications related to voltage control

[0256] In this example, although toner replenishment has been described as an example of the recovery step (R3) executed when DA > DB in the comparison step (S2), further improvement of image defects (foggy images) can be attempted by switching the execution conditions of the image forming operation in addition to toner replenishment. Here, as a modification of Example 4, an image forming apparatus 100 capable of switching the execution mode (printing mode) of the image forming operation between multiple modes will be described.

[0257] Figure 21A 4 is a flowchart illustrating the recovery process according to this modification. Figure 19 ), this process differs in that the mode switching step (R2) is executed when the comparison result in the comparison step (S2) is DA > DB (the density of area A is higher). In other words, the recovery method of this modified example includes a mode switching step for switching the mode of image forming operation between a plurality of modes having different execution conditions for the image forming operation in the image forming apparatus 100, and the mode switching step (R2) is executed when the supplementation step (R3A) is executed.

[0258] Switching the print mode changes at least a portion of the execution conditions for the image forming operation. For example, switching the print mode in this modification refers to increasing the DC component (absolute value) of the charging voltage applied to the charging roller 2 (charging member) from the value of -1350V in Example 1 to -1450V. For example, a method of instructing the image forming apparatus 100 to switch modes may be a method of displaying an operation screen on a display of a computer connected to the image forming apparatus 100 and clicking a mode switching button on the screen. Alternatively, a method of instructing the image forming apparatus 100 may be a button operation on the operation screen of the operation portion 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.

[0259] When the charging voltage is switched from -1350V to -1450V, the surface potential (absolute value) of the photosensitive drum 1 undergoing the charging process by the charging roller 2 increases. In this case, the potential difference Vback between the potential of the developing roller 4 in the developing section N3 (development potential Vdc) and the potential of the non-exposed areas on the photosensitive drum 1 (dark potential VD) increases. The development potential Vdc is the DC component of the development voltage applied to the developing roller 4. The potential difference Vback has the function of suppressing the toner with a relatively small amount of charge on the developing roller 4 from adhering to the non-exposed areas on the photosensitive drum 1 as fogged toner, and is also known as the defogging contrast. Therefore, if it is determined that the cause of the image defect is the mixing of different types of toner (S2: Yes), in addition to performing toner replenishment (R3A), the potential difference Vback is increased by increasing the charging voltage (R2), thereby achieving further improvement in the image defect (foggy image).

[0260] Here, although the example of increasing the charging voltage has been described, similar advantages can also be obtained when the potential difference Vback is increased by increasing the DC component of the developing voltage applied to the developing roller 4 (developing member). In addition, both the charging voltage and the developing voltage can be changed.

[0261] In addition, the controller 90 may perform control so that the mode switching step (R2) of this modification is the same as the lock release step (R3) of the above modification. Figure 20 In addition, if Figure 21B As illustrated in FIG, the mode switching step ( R4 ) may be performed after the toner replenishment ( R3A) is performed.

[0262] In this modification, an example has been described in which, in addition to performing toner replenishment, the print mode is switched when DA > DB in the comparison step (S2). This configuration is not limited to this, and in the comparison step (S2), the print mode (R2) may be switched when DA > DB without performing toner replenishment. In this case, while the improvement effect of toner replenishment on image defects (foggy images) described in Example 4 cannot be achieved, foggy toner can be reduced by changing the charging voltage, thereby at least partially achieving recovery from the image defect.

[0263] Modifications related to sheet inspection

[0264] As another variation, Figure 22 As illustrated in , in the case where DA>DB in the comparison step (S2), the sheet passing inspection step (R5) can be performed after the colorant replenishment (R3A). In the sheet passing inspection step (R5), after causing the image forming apparatus 100 to perform an idling operation, the image forming apparatus 100 is caused to print a predetermined test image on a predetermined number of sheets, thereby inspecting whether the apparatus has recovered from the image defect. The idling operation is an operation of rotationally driving the stirring member 7, the developing roller 4, and the photosensitive drum 1 without forming an image. When the idling operation is performed after the colorant replenishment, most of the different kinds of toners mixed in the developing container 8 are a specific kind of toner (the same kind of toner as the replenished toner), and the friction charging of the newly replenished toner progresses in a state where the chance of charge transfer between the different kinds of toners is reduced. Therefore, during the idling operation, the polarization of the charge amount distribution (see Figure 12B ) is alleviated. The predetermined number is set to, for example, 30, but the configuration is not limited thereto. In addition, in the case of checking the occurrence of a fog image, the test image may be a pure white (blank) image.

[0265] If it is determined in the sheet passage inspection step (R5) that the apparatus has not yet fully recovered from the image defect, the service worker can wait for improvement of the image defect by performing an additional sheet passage inspection step (R5). In addition, in the above case, the service worker can attempt to improve the image defect by, for example, causing the image forming apparatus 100 to perform the preparatory operation described in Example 3.

[0266] Other variations

[0267] In addition, the toner supplied for replenishment in the toner replenishment (R3A) serving as the recovery step may be a toner different from all the toners among the plurality of toners mixed in the developing container 8. This is because, if the ratio of the newly supplied toner among all the toners in the developing container 8 is sufficiently high, image defects caused by mixing of different kinds of toners can be suppressed.

[0268] Example 5

[0269] Next, Example 5 will be described. In Example 5, a series of processes will be described in which a step for recovering from image defects is selectively performed in addition to the determination process described in Example 2. In the following description, it is assumed that elements denoted by the same reference symbols as in Example 2 have substantially the same configuration and function as those described in Example 2, and the parts different from Example 2 will be mainly described.

[0270] Recovery Process

[0271] Will refer to Figure 23 The flow of this example is described. The description is given assuming that this flow is executed by a service worker. Note that the person who executes this determination flow is not limited to a service worker, and a user can execute this flow.

[0272] First, as an output step (S11), the service worker prints the determination pattern TP. Next, as a comparison step (S12), the density DA of area A and the density DB of area B in the determination pattern TP output on the recording material P are visually compared. That is, in the comparison step (S12), the density of the first area and the density of the second area in the pattern image output on the recording material P are compared. If the comparison result in the comparison step (S12) is DA > DB (area A has a higher density), as a recovery step (R14), the service worker attaches a new toner pack 40 to the mounting portion 57 and performs toner replenishment (R14A). Up to this point, the process is the same as in Example 2.

[0273] If the comparison result in the comparison step (S12) is not DA>DB, the service worker proceeds to the print inspection step (S13). The print inspection step (S13) is basically the same as in Example 2. That is, the service worker inspects whether an image other than the determination pattern is formed inside the two reference vertical lines L relative to the determination pattern TP output on the recording material P.

[0274] In such Figure 15A In the case where vertical streaks are present on the inner sides relative to the two reference vertical lines L in the print checking step (S13), the service worker attaches a new toner pack 40 to the mounting portion 57 and performs toner replenishment (R14A) as the recovery step (R14). That is, in the case where it is determined in Example 2 that different kinds of toners are mixed in the developing container 8 (S13: Figure 14 ), as the recovery step (R14) in this example, toner replenishment is performed (R14A).

[0275] In contrast, in Figure 15B In the case where the vertical streaks shown in the figure are outside the two reference vertical lines L or there are no vertical streaks, the service worker performs replacement of the process unit 9 (R14B) as the recovery step (R14). That is, in the case where it is not determined in Example 2 that different kinds of toners are mixed in the developing container 8 (S13: Figure 14 ), as the recovery step (R14) in this example, replacement of the processing unit 9 is performed (R14B).

[0276] Recovering from image defects by toner replenishment

[0277] The reason why it is possible to recover from an image defect by replenishing toner in the case where an image exists on the inner side with respect to the reference vertical line L in the print checking step ( S13 ) will be described.

[0278] As described in Example 2, in a case where a first colorant having a high roundness and a third colorant having a low roundness (that is, having a more uneven shape) are mixed in the developing container 8, the third colorant is bitten by the developing scraper 6, and therefore, an image defect of vertical stripes may appear on the inner side relative to the reference vertical line L.

[0279] In the following description, it will be considered that an image defect in which vertical streaks have occurred due to the mixing of the first toner and the third toner in the developing container 8 and the image defect is performed. Figure 23 In this case, the comparison result in the comparison step (S12) is not DA>DB, the check result in the print check step (S13) is that there are vertical streaks on the inner side (S13: "Yes"), and as the recovery step (R14), toner replenishment (R14A) is performed. The replenished toner is preferably the first toner described below.

[0280] First, the case where the first colorant is replenished in the recovery step (R14) will be described. When the first colorant is replenished, the ratio of the first colorant in all the toners in the developing container 8 increases. In addition, the ratio of the first colorant in the toner carried on the developing roller 4 increases. According to the rotation of the developing roller 4, the third colorant bitten by the developing scraper 6 is gradually removed from the relative portion between the developing scraper 6 and the developing roller 4. When the amount of the third colorant on the developing roller 4 has been sufficiently reduced and the first colorant has become dominant on the developing roller 4, the image defect of the vertical stripes caused by the biting of the toner by the developing scraper 6 is resolved or suppressed.

[0281] Next, the case where the third toner is replenished in the recovery step (R14) will be described. When the third toner is replenished, the proportion of the third toner in the total toner in the developer container 8 increases. Furthermore, the proportion of the third toner in the toner carried on the developer roller 4 increases. In this case, the problem of the toner biting the developer blade 6 is not solved, and therefore it can be considered that the image defect of vertical streaks caused by the toner biting cannot be solved.

[0282] Note that the toner replenished in the recovery step (R14) is not limited to the first toner. It is sufficient as long as the toner is a toner that is unlikely to be bitten by the developing blade 6, that is, a toner having a high circularity. The toner replenished in the recovery step (R14) has, for example, an average circularity of 0.96 or greater as defined in the above formula.

[0283] Modification

[0284] Although a series of processes including a restoration step from an image defect has been described based on Example 2, a series of processes including a restoration step from an image defect may be performed based on Example 3. The process in this case is as follows Figure 24 . If it is determined in Example 3 that different types of toner are mixed in the developing container 8 (S22: Yes, S25: Yes, or S26: Yes), the service worker performs toner replenishment (R27A) as a recovery step (R27). If it is not determined in Example 3 that different types of toner are mixed in the developing container 8 (S26: No), the service worker performs replacement of the process unit 9 (R27B) as a recovery step (R27).

[0285] As a result, advantages similar to those of Example 3 such as improvement in determination accuracy can be obtained, and restoration from an image defect can be achieved by an appropriate method according to the cause of the image defect.

[0286] In addition, the lock release step, mode switching step, and sheet passing inspection step described in the modification of Example 4 may be combined with the above-mentioned Example 5 or the modification. Figure 25 The figure shows the process of combining the mode switching step and the sheet passing inspection step with the above-mentioned modification example ( Figure 24 ) combined. In this process, when it is determined that different kinds of toners are mixed in the developing container 8 (S22: Yes, S25: Yes, or S26: Yes), the mode switching step (R26), the toner replenishment (R27A) serving as the recovery step (R27), and the sheet passing inspection step (R28) are executed. The controller 90 may perform control so that the lock release step ( Figure 20 R1) and the mode switching step (R26) are linked to each other.

[0287] As a result, restoration from an image defect can be achieved by an appropriate method corresponding to the cause of the image defect while obtaining the advantages of each modification.

[0288] Other variations

[0289] In the above example, the image forming device 100 has been described as a direct transfer type monochrome laser beam printer. However, the configuration is not limited thereto, and the image forming device may be an intermediate transfer type that transfers the toner image formed on the photosensitive drum 1 to a recording material via an intermediate transfer member such as an intermediate transfer belt. Alternatively, the image forming device may be a color printer that forms a color image using multiple colors of toner. Note that in the case of a color printer, a determination pattern TP is generated for each color of toner, and a determination is also made regarding the mixing / non-mixing of different types of toner for each color of toner. In this case, the amount compared in the comparison step by visual observation or using a measuring device is not limited to the density of the image and may be color information. For example, the brightness of the halftones in region A and region B or the coordinates in a color space (such as the L*a*b* color space) may be obtained, and the brightness or color coordinates may be compared between region A and region B.

[0290] In addition, although the description is given on the premise that the image forming apparatus 100 has a cleaner-less configuration in the above example, the determination method of the present disclosure may be applied to an image forming apparatus including a cleaning unit that collects transfer residual toner from the photosensitive drum 1 .

[0291] In addition, although the description is given assuming that a service worker (that is, a person) performs each step of the determination method described in each flowchart, the determination method may be partially or entirely performed by the image forming apparatus 100. For example, a densitometer capable of measuring the density of a halftone image may be provided in the image forming apparatus 100, and the image forming apparatus 100 may automatically perform the comparison steps (S2, S12, S25, S34) when executing the determination mode.

[0292] In addition, the above examples have been described as examples of an external replenishment system capable of replenishing developer container 8 (toner storage portion) in an image forming apparatus with toner from outside the apparatus using toner pack 40 (replenishment container). This configuration is not limited to this, and the image forming apparatus may also have a configuration in which a replenishment container (also referred to as a toner cartridge or toner bottle) that holds toner for replenishment is attachable to and detachable from the image forming apparatus main body. In this case, developer container 8 is replenished with toner from the replenishment container attached to the image forming apparatus main body. Furthermore, in this case, if the type of toner already contained in developer container 8 differs from the type of toner newly supplied from the replenishment container, or if the toner in developer container 8 has deteriorated, image defects may occur due to the mixing of different types of toner. Therefore, the determination process described in each example can be used to determine whether an image defect is caused by the mixing of different types of toner.

[0293] Other embodiments

[0294] The embodiment(s) of the present invention may also be implemented by a computer of a system or device that reads and executes computer-executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be more fully referred to as a "non-transitory computer-readable storage medium") to perform the functions of one or more of the above-described embodiment(s) and / or includes one or more circuits (e.g., application-specific integrated circuits (ASICs)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by a computer of the system or device, for example, by reading and executing computer-executable instructions from a storage medium to perform the functions of one or more of the above-described embodiment(s) and / or controlling one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may include one or more processors (e.g., a central processing unit (CPU), a microprocessing unit (MPU)), and may include a network of separate computers or separate processors to read and execute computer-executable instructions. The computer-executable instructions may be provided to the computer, for example, from a network or storage medium. The storage medium may include, for example, a hard disk, a random access memory (RAM), a read-only memory (ROM), a storage device of a distributed computing system, an optical disk (such as a compact disk (CD), a digital versatile disk (DVD), or a Blu-ray disk (BD)). TM ), one or more of flash memory devices, memory cards, etc.

[0295] Other embodiments

[0296] The embodiments of the present invention can also be implemented by the following method, that is, software (including computer program products of computer programs / instructions) that perform the functions of the above-mentioned embodiments is provided to a system or device through a network or various storage media, and a computer (central processing unit (CPU), microprocessing unit (MPU)) of the system or device reads and executes the computer program / instructions.

[0297] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A determination method for determining whether a plurality of toners are mixed in a toner storage portion in an image forming apparatus, the toner storage portion being capable of being replenished with toner by using a replenishment container, the determination method comprising: outputting a pattern image on a recording material by using the image forming device, the pattern image including a first area in which a halftone image is formed and a second area in which another halftone image is formed, the halftone image of the second area being composed of dots having an average dot size smaller than an average dot size of dots constituting the halftone image of the first area; comparing the density of the first area and the density of the second area in the pattern image output on the recording material; and In the case where the visual density of the halftone image of the first area is higher than that of the second area under the illuminance of 30 lux or more in the comparison, it is determined that the plurality of toners are mixed in the toner storage portion.

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

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

4. The determination method according to claim 1, wherein: The halftone image of the first area is composed of dots having an average dot size of 3×3 pixels or more, and the halftone image of the second area is composed of dots having an average dot size of 2×2 pixels or less.

5. The determination method according to claim 1, wherein: The ratio of pixels forming dots in the first area to all pixels of the first area is equal to or higher than the ratio of pixels forming dots in the second area to all pixels of the second area. The determination method according to claim 1 , wherein: The pattern image is formed at a central portion of the recording material in a main scanning direction of image formation.

7. The determination method according to claim 1, wherein: The plurality of toners include a first toner and a second toner having a lower charging performance than the first toner.

8. The determination method according to claim 7, in, The toner particles of the first toner include a core particle and a surface layer including an organic silicon polymer and covering a surface of the core particle, and The toner particles of the second toner do not include a surface layer including an organic silicon polymer.

9. The determination method according to any one of claims 1 to 8, further comprising: checking whether an image other than the pattern image exists in a predetermined area on the recording material in a main scanning direction of image formation, wherein the pattern image includes a boundary line indicating a boundary of the predetermined area, and Here, in the case where an image other than the pattern image exists in the predetermined area in the inspection, it is determined that a plurality of toners are mixed in the toner storage portion.

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

11. The determination method according to claim 9, wherein: The plurality of toners include a first toner and a third toner having a lower average circularity than the first toner.

12. The determination method according to claim 11, in, The first toner is a polymerized toner, and Wherein, the third toner is a powdered toner.

13. A determination method for determining whether a plurality of toners are mixed in a toner storage portion in an image forming apparatus, the toner storage portion being capable of being replenished with toner by using a replenishment container, the determination method comprising: outputting a pattern image on a recording material by using the image forming device, the pattern image including a first area in which a halftone image is formed and a second area in which another halftone image is formed, the halftone image of the second area being composed of dots having an average dot size smaller than an average dot size of dots constituting the halftone image of the first area; comparing the density of the first area and the density of the second area in the pattern image output on the recording material; as well as If the density of the first region is higher than that of the second region in the comparison and a difference between the density of the first region and the density of the second region satisfies a predetermined condition, it is determined that the plurality of toners are mixed in the toner storage portion.

14. The determination method according to claim 13, wherein: In the comparison, the concentration of the first region and the concentration of the second region measured by using a densitometer are compared.

15. The determination method according to claim 14, wherein: The predetermined condition is that a difference between the density of the first region and the density of the second region measured by using the densitometer is 0.01 or more.

16. The determination method according to claim 13, wherein: In the comparison, a determination graph is used to compare a standard image having a concentration closest to the concentration of the first area among a plurality of standard images having different concentration levels with a standard image having a concentration closest to the concentration of the second area among the plurality of standard images, and the determination graph is prepared in advance and includes the plurality of standard images.

17. The determination method according to claim 16, wherein: The predetermined condition is that there is at least one level difference between the density level of a standard image whose density is closest to the density of the first area among the plurality of standard images and the density level of a standard image whose density is closest to the density of the second area among the plurality of standard images in the determination diagram.

18. The determination method according to any one of claims 1 to 8, further comprising: causing the image forming apparatus to perform a preliminary operation for removing fogged toner adhered to a charging roller configured to charge a photosensitive drum, The outputting is performed after the preparatory operation.

19. The determination method according to claim 18, wherein: The preparatory 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 having the same polarity as the normal polarity of the toner to the charging roller and applying a voltage having a polarity opposite to the normal polarity of the toner to the developing roller.

20. The determination method according to claim 18, wherein: The preparatory operation includes the following second operation: rotating the photosensitive drum while 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 of the toner to the charging roller and simultaneously applying a voltage of a polarity opposite to the normal polarity of the toner to the developing roller.

21. The determination method according to claim 18, wherein: It is determined that the plurality of toners are mixed in the toner storage portion when a level of an image other than the pattern image generated in the predetermined area when the pattern image is output after the preparatory operation is improved compared to an image other than the pattern image generated in the predetermined area when the pattern image is output before the preparatory operation.

22. A determination method for determining whether a plurality of toners are mixed in a toner storage portion in an image forming apparatus, the toner storage portion being capable of being replenished with toner by using a replenishment container, the determination method comprising: outputting a first pattern image on a first recording material by using the image forming device, the first pattern image including a boundary line indicating a boundary of a predetermined area in a main scanning direction of image formation; checking whether an image other than the first pattern image exists in the predetermined area on the first recording material; as well as Based on a result of the checking, it is determined whether the plurality of toners are mixed in the toner storage portion.

23. The determination method according to claim 22, further comprising: causing the image forming apparatus to perform a preliminary operation for removing fogged toner after the outputting, the fogged toner being attached to a charging roller configured to charge a photosensitive drum; outputting a second pattern image on a second recording material by using the image forming device after the preparatory operation, the second pattern image including a first area in which a halftone image is formed, a second area of the halftone image composed of dots having an average dot size smaller than dots constituting the halftone image of the first area, and the boundary line; checking whether an image other than the second pattern image exists in the predetermined area on the second recording material; as well as comparing the density of the first area and the density of the second area in the second pattern image output on the second recording material, Wherein, in the determination, whether the plurality of toners are mixed in the toner storage portion is determined based on checking whether there is an image other than the first pattern image in the predetermined area on the first recording material, checking whether there is an image other than the second pattern image in the predetermined area on the second recording material, and the result of the comparison.

24. The determination method according to claim 23, wherein: In the case where an image other than the first pattern image exists in the predetermined area on the first recording material, in the case where an image other than the second pattern image exists in the predetermined area on the second recording material, and in the case where the concentration of the first area is higher than the concentration of the second area in the comparison, it is determined in the determination that the multiple colorants are mixed in the colorant storage part.

25. The determination method according to claim 22, further comprising: causing the image forming apparatus to perform a preliminary operation for removing fogged toner after the outputting, the fogged toner being attached to a charging roller configured to charge a photosensitive drum; outputting a second pattern image including the boundary line on the second recording material by using the image forming device after the preparatory operation; as well as checking whether an image other than the second pattern image exists in the predetermined area on the second recording material, Wherein, in a case where there is an image other than the first pattern image in the predetermined area on the first recording material, (i) when the level of the image other than the second pattern image produced in the predetermined area on the second recording material is improved compared with the image other than the first pattern image produced in the predetermined area on the first recording material, it is determined in the determination that the multiple colorants are mixed in the colorant storage part, and (ii) when the level of the image other than the second pattern image produced in the predetermined area on the second recording material is not improved compared with the image other than the first pattern image produced in the predetermined area on the first recording material, it is determined in the determination that the multiple colorants are not mixed in the colorant storage part.

26. A recovery method for recovering an image forming apparatus from an image defect, the image forming apparatus including a toner storage portion capable of being replenished with toner by using a replenishment container, the recovery method comprising: outputting a pattern image on a recording material by using the image forming device, the pattern image including a first area in which a halftone image is formed and a second area in which another halftone image is formed, the halftone image of the second area being composed of dots having an average dot size smaller than an average dot size of dots constituting the halftone image of the first area; comparing the density of the first area and the density of the second area in the pattern image output on the recording material; as well as replenishing the toner storage portion with toner, The supplementation is performed when the visual density of the halftone image in the first area is higher than the visual density of the second area under the condition of illuminance of 30 lux or greater in the comparison.

27. The recovery method according to claim 26, further comprising: replacing at least a portion of an image forming mechanism included in the image forming apparatus, The replacement is performed when it is not recognized that the visual density of the first area is higher than the visual density of the second area in the comparison under the conditions.

28. The recovery method according to claim 26, wherein: When the replenishment is performed in a state where a first toner and a second toner having a lower charging performance than the first toner are mixed in the toner storage portion, the toner storage portion is replenished with the first toner or the second toner.

29. The recovery method according to claim 26, further comprising: checking whether an image other than the pattern image exists in a predetermined area on the recording material in a main scanning direction of image formation, wherein the pattern image includes a boundary line indicating a boundary of the predetermined area, and The supplementation is performed when an image other than the pattern image exists in the predetermined area during the inspection.

30. The recovery method according to claim 29, wherein: In a case where the replenishment is performed in a state where a first toner and a third toner having a lower average circularity than the first toner are mixed in the toner storage portion, the toner storage portion is replenished with the first toner.

31. A recovery method for recovering an image forming apparatus from an image defect, the image forming apparatus including a toner storage portion capable of being replenished with toner by using a replenishment container, the recovery method comprising: outputting a pattern image on a recording material by using the image forming device, the pattern image including a first area in which a halftone image is formed and a second area in which another halftone image is formed, the halftone image of the second area being composed of dots having an average dot size smaller than an average dot size of dots constituting the halftone image of the first area; comparing the density of the first area and the density of the second area in the pattern image output on the recording material; as well as replenishing the toner storage portion with toner, The supplementation is performed when the concentration of the first region is higher than the concentration of the second region in the comparison and a difference between the concentration of the first region and the concentration of the second region satisfies a predetermined condition.

32. A recovery method for recovering an image forming apparatus from an image defect, the image forming apparatus including a toner storage portion capable of being replenished with toner by using a replenishment container, the recovery method comprising: outputting a first pattern image on a first recording material by using the image forming device, the first pattern image including a boundary line indicating a boundary of a predetermined area in a main scanning direction of image formation; checking whether an image other than the first pattern image exists in the predetermined area on the first recording material; as well as replenishing the toner storage portion with toner, The supplementation is performed when an image other than the first pattern image exists in the predetermined area during the inspection.

33. The recovery method according to claim 32, further comprising: causing the image forming apparatus to perform a preliminary operation for removing fogged toner after the outputting, the fogged toner being attached to a charging roller configured to charge a photosensitive drum; After the preparatory operation, outputting a second pattern image on a second recording material by using the image forming device, the second pattern image including a first area in which a halftone image is formed, a second area in which another halftone image is formed, and the boundary line, the halftone image of the second area being composed of dots having an average dot size smaller than an average dot size of dots constituting the halftone image of the first area; checking whether an image other than the second pattern image exists in the predetermined area on the second recording material; as well as comparing the density of the first area and the density of the second area in the second pattern image output on the second recording material, The supplementation is performed in the case where an image other than the first pattern image exists in the predetermined area on the first recording material, in the case where an image other than the second pattern image exists in the predetermined area on the second recording material, and in the case where the visual density of the halftone image of the first area is higher than the visual density of the halftone image of the second area in the comparison.

34. The recovery method according to any one of claims 29 to 33, in, The image forming apparatus includes a lock mechanism capable of taking a locked state that restricts toner replenishment of the toner storage portion using the replenishment container and a locked unlocked state that allows the toner replenishment, and The recovery method further includes: When the replenishment is performed, the lock mechanism is switched from the locked state to the unlocked state.

35. The recovery method according to any one of claims 29 to 33, further comprising: switching a mode of the image forming operation between a plurality of modes having different execution conditions for the image forming operation in the image forming apparatus, The switching is performed when the supplementation is performed.

36. The recovery method according to claim 35, in, The image forming apparatus includes a photosensitive member, a charging member configured to charge a surface of the photosensitive member, and a developing member configured to supply toner to the photosensitive member to develop a latent image on the surface of the photosensitive member into a toner image, and Here, in the switching, 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.

37. The recovery method according to any one of claims 29 to 33, further comprising: After the replenishment, a predetermined test image is formed on a recording material by using the image forming apparatus to check improvement with respect to the image defect.

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