Developing device, image forming apparatus, developer storage body, and developer filling method

Abstract

To increase image fixability of a developer image printed on a medium even when the initial amount of developer stored in a developing device is increased.SOLUTION: A developing device (10) has: an image carrier (11) that carries an electrostatic latent image and is rotatable about a rotation axis; a storage unit (15) that stores a developer (21b) in which a first developer (A) and a second developer (B) having a higher softening point temperature (T1 / 2) than the first developer (A) are mixed; and a developer carrier (12) that develops the electrostatic latent image. When a first weight ratio of the first developer (A) in the developer (21b) is defined as α, and a second weight ratio of the second developer (B) in the developer (21b) as 1-α, α is 0.2 or more and less than 1. The weight percentage (P) of the weight (N) of the developer (21b) stored in the storage unit (15) to the maximum weight (M) of developer that can be stored in the storage unit (15) is 20% or more.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a developing device, an image forming apparatus having the developing device, a developer container attached to the developing device, and a developer filling method for filling the developing device or the developer container with developer. [Background technology]

[0002] A developing device (image forming unit) of an electrophotographic image forming apparatus contains a developer used to develop an electrostatic latent image formed on the surface of a photosensitive drum (see, for example, Patent Document 1). In general, the initial developer contained in a new (e.g., immediately after purchase) developing device may have different characteristics from the replenishment developer contained in a developer container (toner cartridge) that supplies the developing device with developer. This is because the initial developer contained in the developing device is required to have characteristics that are unlikely to change even over a long period of time.

[0003] Therefore, since the image fixability may differ between printed matter printed using the initial developer and printed matter printed using the replenishment developer, conventional developing devices have reduced the difference in image fixability between printed matter printed using the initial developer and printed matter printed using the replenishment developer by setting the amount of initial developer stored in advance to a small amount. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-276660 Summary of the Invention [Problem to be solved by the invention]

[0005] However, there is a demand for increasing the amount of initial developer pre-stored in the developing device, but if the amount of initial developer is increased, there is a problem that developer images with poor image fixability are formed for a long period of time until the developer is replaced with replenishment developer.

[0006] The present disclosure aims to provide a developing device, an image forming device, a developer container, and a developer filling method that can improve the image fixability of a developer image printed on a medium while ensuring high storage stability of the initial developer. [Means for solving the problem]

[0007] The developing device disclosed herein comprises an image carrier that carries an electrostatic latent image and is rotatable around a rotation axis; a storage section that stores a developer that is a mixture of a first developer and a second developer that has a softening point temperature higher than that of the first developer; and a developer carrier that develops the electrostatic latent image with the developer, wherein when a first weight ratio of the first developer in the developer is α and a second weight ratio of the second developer in the developer is 1-α, α is greater than or equal to 0.2 and less than 1, and the weight percentage of the weight of the developer stored in the storage section relative to the maximum weight of the developer that can be stored in the storage section is 20% or greater.

[0008] Another developing device disclosed herein is the above-described developing device, further comprising a developer container that contains the developer, and the developer is supplied from the developer container to the container portion.

[0009] The image forming apparatus of the present disclosure is characterized by including any one of the developing devices described above.

[0010] The developer container of the present disclosure is a container that is attached to a developing device having a storage section for storing developer, and stores developer to be supplied into the storage section, wherein the developer is a mixture of a first developer and a second developer having a softening point temperature higher than that of the first developer, and wherein when a first weight ratio of the first developer in the developer is α and a second weight ratio of the second developer in the developer is 1-α, α is 0.2 or more and less than 1, and the weight percentage of the weight of the initial developer stored in the storage section relative to the maximum weight of developer that can be stored in the storage section is 20% or more.

[0011] The developer filling method disclosed herein is a method for filling a developer containing a mixture of a first developer and a second developer having a softening point temperature higher than that of the first developer into a storage section of a developing device, and is characterized by including at least a first step of mixing the first developer and the second developer to produce the developer so that α is 0.2 or more and less than 1, where α is the weight ratio of the first developer in the developer and α is 1-α, and a second step of filling the developer into the storage section so that the weight percentage is 20% or more of the maximum weight of developer that can be stored in the storage section.

[0012] Another developer filling method disclosed herein is a method of filling a developer container with a developer that is a mixture of a first developer and a second developer that has a softening point temperature higher than that of the first developer, and is characterized by including at least a first step of mixing the first developer and the second developer to produce the developer so that α is 0.2 or more and less than 1, where α is the weight ratio of the first developer in the developer and α is 1-α, and a second step of filling the developer into the container so that the weight percentage is 20% or more of the maximum weight of developer that can be contained in the container. [Effects of the Invention]

[0013] According to the present disclosure, even when the initial developer capacity is large, it is possible to ensure high storage stability of the initial developer and obtain good image fixability of the developer image printed on the medium. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic cross-sectional view showing a configuration of an image forming apparatus according to an embodiment. [Figure 2] FIG. 2 is a block diagram showing a configuration of a control system of the image forming apparatus according to the embodiment. [Figure 3] 5A and 5B are diagrams illustrating a method for measuring the resistance value of a developing roller of a developing device according to an embodiment. [Figure 4] 10(a) and 10(b) are diagrams showing a method for measuring the pressure between the photosensitive drum and the developing roller. [Figure 5] 1 is a schematic cross-sectional view showing a configuration of a developing device (image forming unit) according to an embodiment. [Figure 6] 1 is a schematic cross-sectional view showing a configuration of a developer carrier (initial developer carrier that accommodates initial developer) according to an embodiment. [Figure 7] (a) and (b) are figures showing examples of initial developer storage ratios, which are the weight percentages of the initial developer stored in the storage section of a developing device relative to the maximum weight of developer that can be stored in the storage section. [Figure 8] 1A and 1B are schematic diagrams showing print patterns used when measuring the image fixation rate of a printed image. [Figure 9] The results of the evaluation test of image fixing property are shown in Table 1. [Figure 10] 1A and 1B are diagrams showing examples of streaks, which are image defects that can occur in a printed image after being left unused for a long period of time. [Figure 11] The results of the evaluation tests for the image fixation of the printed image and the storage stability of the initial developer are shown in Table 2. [Figure 12] 1A to 1C are diagrams illustrating an example of mixing two types of developers. [Figure 13]The results of the evaluation tests for the image fixation of the printed image and the storage stability of the initial developer are shown in Table 3. [Figure 14] 1A to 1C are schematic diagrams showing examples of dot arrangements of developer particles adhering to an adhesive tape used for evaluating the image fixing rate of a printed image. [Figure 15] 10A to 10C are schematic diagrams showing the state of developer adhering at the contact portion between the photosensitive drum and the developing roller immediately before the start of printing after a long period of non-use. DETAILED DESCRIPTION OF THE INVENTION

[0015] Below, we will explain the developing device according to the embodiment, an image forming apparatus having the developing device, a developer container that contains developer to be supplied to the developing device, and a developer filling method for filling the developing device or developer container with developer, with reference to the drawings.

[0016] The developing device according to the embodiment is also called an "image forming unit" or an "image drum (ID) unit." The initial developer (i.e., the initial toner) contained in the developing device according to the embodiment has a softening point temperature T 1 / 2 (or glass transition temperature T g The initial developer is a mixed developer (i.e., mixed toner) in which multiple types of developers (i.e., toners) (different in number) are mixed. In the following explanation, a case will be explained in which the multiple types of developers include a first developer A and a second developer B. The initial developer is, for example, a developer that is stored in advance in the storage section of a new developing device when the device is purchased. The initial developer has different properties from the replenishment developer that is replenished from a replenishment developer storage unit (i.e., a replenishment toner cartridge) during normal use.

[0017] The image forming apparatus according to the embodiment is a printing apparatus, i.e., a printer, that forms an image on a medium using an electrophotographic process. The image forming apparatus according to the embodiment may also be a copier, a facsimile, or a multifunction peripheral. The image forming apparatus according to the embodiment has a developing device, and the initial developer contained in the developing device has a softening point temperature T 1 / 2 (or glass transition temperature T g Multiple types of developers (e.g., different softening temperatures T 1 / 2 It is a mixed developer that is a mixture of two different types of developers.

[0018] The developer container according to the embodiment is a developer container (i.e., a toner cartridge) that supplies initial developer to the developing device. The developer container according to the embodiment is formed so as to be detachable from the developing device. The developer container according to the embodiment has a softening point temperature T 1 / 2 (or glass transition temperature T g Multiple types of developers (e.g., different softening temperatures T 1 / 2 By attaching the initial developer container to the developing device, the initial developer can be supplied to the container of the developing device.

[0019] The developer filling method according to the embodiment is a method for filling (i.e., supplying) an initial developer into a developing device or a developer container. The developer filling method is mainly used in the manufacturing stage of a developing device or a developer container. The initial developer filled by the developer filling method according to the embodiment has a softening point temperature T 1 / 2 (or glass transition temperature T g Multiple types of developers (e.g., different softening temperatures T 1 / 2 The softening point temperature T 1 / 2 The mixed developer having different properties is a developer in which a first developer is mixed with a second developer having a softening point temperature higher than that of the first developer. In a developer filling method for filling a developer into a container of a developing device or a developer container, a first step of mixing the first developer and the second developer to generate the developer, where α is a weight ratio of the first developer in the developer and 1-α is a weight ratio of the second developer in the developer, so that α is equal to or greater than 0.2 and less than 1; a second step of filling the developer into the container so that the developer accounts for 20% or more by weight of the maximum weight of the developer that can be contained in the container; At least includes.

[0020] The following embodiments are merely examples, and may be modified as appropriate. In the drawings, the same reference numerals are used to designate the same or similar components.

[0021] <1> Configuration of the embodiment 1-1 Structure of image forming device 1 FIG. 1 is a schematic cross-sectional view showing the configuration of an image forming apparatus 1 according to an embodiment. As shown in FIG. 1, image forming apparatus 1 is a monochrome printer that can print an image on a medium 80 such as paper by an electrophotographic process using a developer (i.e., toner). While FIG. 1 shows a case in which medium 80 is cut paper, medium 80 may also be a continuous medium such as roll paper. Image forming apparatus 1 may also be a color printer, in which case image forming apparatus 1 includes multiple developing devices (i.e., multiple image forming units).

[0022] 1, the image forming apparatus 1 has a developing device 10 that forms a developer image (i.e., a toner image) made of developer on a photosensitive drum 11 that serves as an image carrier, and a transfer roller 40 that serves as a transfer member that transfers the developer image formed on the photosensitive drum 11 onto a medium (also called a "recording medium") 80 such as paper. The developing device 10 is detachably mounted in a housing 1a that is the main body of the image forming apparatus 1.

[0023] The image forming device 1 further includes a medium supply and transport section 30 that supplies and transports the medium 80, a fixing unit 50, and a pair of rollers 60 as a medium discharge section that discharges the medium 80 that has passed through the fixing unit 50 to the outside of the housing 1a.

[0024] 1, the medium supply and conveyance unit 30 mainly comprises a medium cassette 31, a hopping roller 32 that feeds out a medium 80 one sheet at a time from a plurality of media loaded in the medium cassette 31, and a roller pair 33 that conveys the medium 80 fed out from the medium cassette 31. The medium supply and conveyance unit 30 may also include other components such as other conveyance rollers and a medium sensor.

[0025] An optical head 70 serving as an exposure unit is provided above the developing device 10. The optical head 70 includes a light-emitting element array in which a plurality of light-emitting elements are arranged in the axial direction of the photosensitive drum 11 (a direction perpendicular to the plane of the paper on which FIG. 1 is drawn). The plurality of light-emitting elements are, for example, a plurality of light-emitting diodes (LEDs) or a plurality of light-emitting thyristors. Exposure by the optical head 70 is performed on the uniformly charged surface of the photosensitive drum 11 based on image data for printing. The exposure unit may be configured as a laser optical system including a laser light source and a laser light scanning optical system.

[0026] The developing device 10 includes a photosensitive drum 11 rotatably supported about a central axis, a charging roller 18 as a charging member that uniformly charges the surface of the photosensitive drum 11, and a developing roller 12 that forms a developer image corresponding to the electrostatic latent image on the surface of the photosensitive drum 11 by exposure to light from an optical head 70 and then supplies a developer to the surface of the photosensitive drum 11. The photosensitive drum 11 is composed of, for example, a cylindrical conductive support and a photosensitive layer coated on its surface. The photosensitive layer has a structure in which a blocking layer, a charge generation layer, and a charge transport layer are laminated in this order from the surface of the conductive support.

[0027] Developing device 10 includes at least photosensitive drum 11 as an image carrier and developing roller 12 as a developer carrier that supplies developer to the surface of photosensitive drum 11, both housed in developer container 15. Developing device 10 also includes supply roller 13 as a supply member that supplies the developer contained in container 15 to developing roller 12, and regulating blade 14 as a regulating member that regulates the thickness of the developer layer on the surface of developing roller 12. Developing device 10 also includes agitating members 16a, 16b, and 16c housed in developer container 15. Agitating members 16a, 16b, and 16c are crank-shaped rods that function as agitating mechanisms that agitate developer 21 supplied from developer container 20. Agitating members 16a, 16b, and 16c rotate in the directions indicated by the arrows. The developing device 10 also has a cleaning blade 19 as a cleaning member for collecting developer remaining on the photosensitive drum 11 .

[0028] The fixing device 50 has a pair of rollers, a heating roller 51 and a pressure roller 52, which are in pressure contact with each other. The heating roller 51 has a built-in heater. The pressure roller 52 is pressed against the heating roller 51. A medium 80 having an unfixed developer image thereon passes between the heating roller 51 and the pressure roller 52. At this time, the unfixed developer image is heated and pressurized to be fixed onto the medium 80.

[0029] A discharge path and a pair of discharge rollers 26 are provided downstream of the fixing unit 50 for discharging the medium 80 to the outside of the housing 1a, and the discharged medium 80 is discharged into a stacker on the housing 1a.

[0030] In this embodiment, a contact development system is used. Developing roller 12 supplies developer while in contact with photosensitive drum 11 to develop the electrostatic latent image. Photosensitive drum 11 and developing roller 12 rotate in opposite directions, and as shown in FIG. 1, near the contact point between photosensitive drum 11 and developing roller 12, the contacting portion of photosensitive drum 11 and the contacting portion of developing roller 12 move in the same direction. Supply roller 13 negatively charges the developer through friction with developing roller 12 and scrapes off any undeveloped developer on developing roller 12. In addition, a seal 17 is provided near the bottom of storage compartment 15 to prevent developer leakage.

[0031] Medium 80 is transported in the directions of arrows 81 to 84 by hopping roller 32, roller pair 33, and roller pair 60. Transfer roller 40 is a transfer means for transferring the developer image formed on the surface of photosensitive drum 11 onto medium 80. The transferred developer image is fixed to medium 80 by fixator 50.

[0032] <1-2> Control system of image forming apparatus 1 Fig. 2 is a block diagram showing a schematic configuration of a control system of image forming apparatus 1. As shown in Fig. 2, image forming apparatus 1 includes a controller 124, a recording control unit 123, a charging voltage control unit 118 that applies a charging voltage to charging roller 18 of developing device 10, a developing voltage control unit 119 that applies a developing voltage to developing roller 12, and a supply voltage control unit 121 that applies a supply voltage to supply roller 13. Image forming apparatus 1 also includes a transfer voltage control unit 122 that applies a transfer voltage to transfer roller 40, a regulating blade voltage control unit 125 that applies a regulating blade voltage to regulating blade 14, an emission control unit 126 that causes optical head 70 to emit light in accordance with input image data, and a fixing control unit 129 that controls the heater of fixing unit 50. Furthermore, the image forming apparatus 1 has a motor control unit 130 that controls the drive of each motor that rotates the motor that rotates the photosensitive drum 11 of the developing device 10, the hopping roller 32 that feeds and transports the medium 80, the roller pairs 33 and 34, the transfer roller 40, etc. The recording control unit 123 is controlled by a controller 124 that is responsible for the overall control of the image forming apparatus 1.

[0033] The image forming apparatus 1 also has a communication unit (not shown) that communicates with external devices, a user operation unit (not shown) that inputs user instructions, and a group of sensors (not shown) that detect the position of the medium 80.

[0034] The image forming apparatus 1 has a recording control unit 123 and a controller 124 (for example, a processor such as a CPU (Central Processing Unit)), memory 120 such as a ROM (Read Only Memory) and a RAM (Random Access Memory), input / output ports, a timer, etc., and controls the overall operation of the image forming apparatus 1 by executing a predetermined program. Specifically, the recording control unit 123 receives print data and control commands from an external device such as a personal computer, and causes each unit of the image forming apparatus 1 to perform a print operation.

[0035] <<1-3>> Printing operation of image forming device 1 Next, we will explain the printing operation of the image forming apparatus 1. The recording control unit 123 starts the printing operation when it receives a print command and print data from the host device. The recording control unit 123 temporarily records the print data received from the host device in memory 120, and then edits the recorded print data to generate image data.

[0036] Furthermore, the fixing control unit 129 drives the fixing motor to start rotating the heating roller 51 and the pressure roller 52. Furthermore, the fixing control unit 129 energizes the heater in the heating roller 51, and the heating roller 51 is heated to a predetermined fixing temperature.

[0037] The motor control unit 130 also drives the transport motor, causing the hopping roller 32 to send the medium 80 in the medium cassette 31 to the transport path. The roller pairs 33 and 60 also rotate to transport the medium 80. A charging voltage, a developing voltage, a supply voltage, and a blade voltage are applied to the charging roller 18, the developing roller 12, and the supply roller 13 of the developing device 10, respectively.

[0038] In addition, the photosensitive drum 11 in the developing device 10 is rotated by the motor control unit 130. As the photosensitive drum 11 rotates, the charging roller 18, the developing roller 12, and the supply roller 13 also rotate. The charging roller 18 uniformly charges the surface of the photosensitive drum 11.

[0039] Furthermore, the light emission control unit 126 drives the optical head 70 to irradiate the surface of the photosensitive drum 11 with light. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 11.

[0040] The electrostatic latent image formed on the surface of the photosensitive drum 11 is developed by the developer attached to the developing roller 12, and a developer image is formed on the surface of the photosensitive drum 11. Furthermore, a transfer voltage is applied to the transfer roller 40 from the transfer voltage control unit 122.

[0041] This transfer voltage causes the developer image on the surface of the photosensitive drum 11 to be transferred to the medium 80 passing between the photosensitive drum 11 and the transfer roller 40. The developer that has not been transferred to the medium 80 is scraped off by the cleaning blade 19.

[0042] In the fixing unit 50, heat and pressure are applied to the medium 80 as it passes through the fixing nip between the heating roller 51 and the pressure roller 52, and the developer image is fixed to the medium 80. The medium 80 with the fixed developer image is sent to the medium discharge section, where a pair of rollers 60 discharges the medium 80 from the discharge port. The discharged medium 80 is stacked on a stacker at the top of the housing 1a. This completes the formation of the image on the medium 80.

[0043] 1-3 Developing device 10 The developer 21 contained in the developing device 10 is a non-magnetic, single-component, negatively charged developer. It is composed of developer base particles containing at least a binder resin to which external additives such as inorganic or organic fine powders (hereinafter referred to as "external additives") are added. The binder resin is not particularly limited, but polyester resin, styrene-acrylic resin, epoxy resin, or styrene-butadiene resin is preferred. The binder resin may contain a release agent, a colorant, or other additives, such as a charge control agent, a conductivity adjuster, a flowability improver, or a cleaning improver. The binder resin may also be a mixture of multiple types. In this embodiment, a crystalline polyester resin (CPES) with a crystalline structure is used in addition to multiple amorphous polyester resins. The average particle size of the developer 21 is approximately 7.0 μm, and the circularity is approximately 0.93. The average particle size is measured using a Coulter Multisizer III manufactured by Coulter, and the circularity is measured using a flow particle image analyzer FPIA-3000 manufactured by Sysmex Corporation.

[0044] The supply roller 13 is configured with a foamed elastic layer made of silicone rubber disposed on a conductive core shaft. The core may be made of any material, as long as it has good electrical conductivity, such as iron, aluminum, or stainless steel. The rubber composition forming the foamed elastic layer contains rubber, a foaming agent, a conductivity imparting agent, and, optionally, various additives. Silicon or silicone-modified rubber is preferred for its excellent heat resistance and electrostatic charge characteristics. Any foaming agent may be used for foamed rubber. For example, inorganic foaming agents include sodium bicarbonate and ammonium carbonate, while organic foaming agents include organic azo compounds such as diazoamino derivatives, azonitrile derivatives, and azodicarboxylic acid derivatives. Inorganic foaming agents are used to form open cells in the foamed elastic layer, while organic foaming agents are used to form closed cells. The various additives include fillers, colorants, release agents, and the like, and are blended in the desired amounts. The shape is not particularly limited, and may be straight or have a difference in outer diameter between the longitudinal end and center, but a configuration that ensures uniform pressure distribution with the developing roller 12 in the longitudinal direction is desirable. In this embodiment, a straight shape with a central outer diameter of 15.5 mm is used. The outer diameter of the shaft is 6.0 mm. Although not particularly limited, the average cell diameter is desirably 200 μm to 500 μm. The hardness is desirably approximately 50 degrees to 65 degrees on the Asker F scale, and in this embodiment, a hardness of 50 degrees to 58 degrees is used. The resistance value is desirably approximately 3.5 log Ω to 7.5 log Ω.

[0045] The resistance value was measured using the method shown in Figures 3(a) and (b) using a measuring device 165, a Hewlett-Packard high resistance meter (model number: 4339B). A load of W = 200 g was applied to both axial ends of the supply roller 13, and the supply roller 13 was brought into contact with a metal roller 166 made of SUS (Steel Use Stainless Steel) with a diameter of 30 mm. The metal roller 166 was rotated at a speed of 63 rpm, and a voltage of DC -300 V was applied to the core of the supply roller 13. The measurement was performed in an environment of 20 °C and 50 % humidity. In this embodiment, a resistance of 5.5 log Ω was used. The supply roller 13 was produced by first integrating a conductive shaft (core) and conductive silicone rubber foam, which had been washed with an organic solvent or the like to remove oil, in an extrusion molding machine. The roller was then passed through an infrared oven or the like to foam and harden the material. After that, a secondary vulcanization treatment is carried out at approximately 180°C to 225°C for 5 to 10 hours, and the desired outer diameter is obtained using a grinding machine. Note that conductive carbon black is used as the conductivity imparting agent.

[0046] The device includes an elastic layer disposed on a conductive core metal as a shaft, and a surface layer that covers the surface of the elastic layer. The elastic layer can be made of a common rubber material such as silicone or urethane. When polyurethane is used for the elastic layer, it is preferable that the polyurethane be primarily made of polyether polyol.

[0047] The photosensitive drum 11 has a layered structure consisting of a drum gear, a drum flange, and a cylindrically processed conductive support, which are layered in this order from the surface, with an undercoat layer, a charge generation layer, and a charge transport layer, and the photosensitive layer is composed of the charge generation layer and the charge transport layer. The photosensitive layer can have any structure applicable to known electrophotographic photosensitive members.

[0048] The regulating blade 14 is made of stainless steel and has a plate thickness of 0.08 mm, and is bent at the portion that comes into contact with the developing roller 12. The radius of curvature of the bent portion is, for example, about 0.15 mm to 0.35 mm, and the pressure (linear pressure) on the developing roller 12 is preferably, for example, about 25 gf / cm to 50 gf / cm, and in this embodiment, a linear pressure of 45.5 gf / cm is used.

[0049] The charging roller 18 is made of epichlorohydrin rubber coated with isocyanate, has an outer diameter of 12 mm, and a ten-point surface roughness of about 10 μm to 20 μm.

[0050] Next, a method for measuring the pressure between the photosensitive drum 11 and the developing roller 12 will be described using FIGS. 4(a) and 4(b). The photosensitive drum 11 and the developing roller 12 are rotated in the direction of the arrows, and a polyethylene terephthalate (PET) film 132 is inserted between the two components. The upper part of the film 132 is reinforced with an acrylic plate 133, which has a hole 134. A metal hook 135 is hooked into the hole 134, and the pressure is measured with a connected digital force gauge 131. The rotational speed of the photosensitive drum 11 is 49 pages per minute (ppm), and the developing roller 12 rotates at a peripheral speed 1.26 times that of the photosensitive drum 11. The data from the digital force gauge 131 is output to a PC, and the average value of the results measured over 5 seconds at a sampling interval of 10 ms is calculated. This is defined as the photosensitive drum-developing roller pull-out force [N]. In this embodiment, the pulling force is adjusted to about 0.8 [N] to 1.1 [N].

[0051] The heating roller 51 of the fixing unit 50 is made of a base tube made of aluminum alloy or the like, coated with a fluororesin such as PFA (perfluoroalkoxyalkane), ensuring release properties and preventing the print medium from wrapping around it. The heating roller 51 is heated to a predetermined temperature by the fixing control unit 129, and applies a pressure of 800 [gf / cm] to the pressure roller 52. 2 ]~850[gf / cm 2], the contact width is 6.0 [mm], and the contact area is 40.5 [cm 2 ] is desirable.

[0052] 1-4 Developing device 10 5 is a schematic cross-sectional view showing the configuration of the developing device 10 according to the embodiment. The developing device 10 shown in FIG. 3 is a developing device that contains a first developer A and a second developer B having a softening point temperature T 1 / 2 The storage section 15 stores an initial developer 21b in which the first developer A is mixed with a second developer B having a higher molecular weight. When a first weight ratio of the first developer A in the initial developer 21b is α and a second weight ratio of the second developer B in the initial developer 21b is 1-α, α is equal to or greater than 0.2 and less than 1. An initial developer storage ratio P [%], which is the weight percentage of the weight N [g] of the initial developer 21b stored in the storage section 15 to the maximum weight M [g] of the developer that can be stored in the storage section 15, is equal to or greater than 20 [%], and preferably equal to or greater than 20 [%] and equal to or less than 70 [%].

[0053] 1-5 Developer container 20a 6 is a schematic cross-sectional view showing the configuration of a developer storage body 20a (initial developer storage body storing initial developer 21b) according to an embodiment. The developing device 10 in FIG. 6 has a storage section 15 that stores developer, and an attachment section 10a to which the developer storage body 20a that stores the initial developer 21b to be supplied into the storage section 15 is attached. The initial developer 21b stored in the developer storage body 20a is supplied to the developing device 10 in FIG. 6. The initial developer 21b has a softening point temperature T 1 / 2 The initial developer 21b is a mixed developer in which the first developer A is mixed with the second developer B having a higher molecular weight. When a first weight ratio of the first developer A in the initial developer 21b is α and a second weight ratio of the second developer B in the initial developer 21b is 1-α, α is equal to or greater than 0.2 and less than 1. The initial developer storage ratio P [%], which is the weight percentage of the weight N [g] of the initial developer 21b stored in the storage section 15 to the maximum weight M [g] of the developer that can be stored in the storage section 15, is equal to or greater than 20 [%], and preferably equal to or greater than 20 [%] and equal to or less than 70 [%].

[0054] <2> Operation of the embodiment 2-1 Evaluation test The following describes an evaluation test of the relationship between the amount of initial developer 21b contained in the developing device 10 of the image forming apparatus 1 and image fixability. For the evaluation test, a monochrome LED printer "B432" manufactured by OKI Electric Industry Co., Ltd. was used as the image forming apparatus 1.

[0055] 7(a) and (b) are diagrams showing examples of the initial developer storage ratio (i.e., initial toner storage ratio) P [%], which is the weight percentage of the weight N [g] of the initial developer 21b stored in the storage section 15 relative to the maximum weight M [g] of the developer that can be stored in the storage section 15 of the developing device 10. The initial developer storage ratio P [%] is defined by the following equation (1).

[0056]

number

[0057] FIG. 7(a) shows the case where the storage section 15 stores a maximum weight of developer M [g] (when P=100[%]). FIG. 7(b) shows the case where the storage section 15 stores an initial amount of developer 21b N [g] (when P=20[%]), where M≧N. In FIGS. 7(a) and (b), the upper limit of the amount of developer 21 that can be stored in the storage section 15 is shown as a storage limit line 41a.

[0058] 8(a) and (b) are schematic diagrams showing print patterns used when measuring the image fixation rate of images printed by the image forming apparatus 1. In the image fixation evaluation test, after the developer container 20 is attached to the developing device 10, 10 blank images are printed on A4 size paper fed lengthwise, and after the fixing unit 50 has sufficiently warmed up, the print pattern shown in FIG. 8(a) is printed on 50 A4 size paper fed lengthwise.

[0059] As shown in FIG. 8(a), the printed image has three square solid areas arranged at equal intervals as a predetermined print pattern near the center in the horizontal direction along the printing direction. The printing speed of the image forming apparatus 1 used was 100 s, and the printing speed was 100 s when printing on ordinary plain paper (basis weight 68 [g / cm 2 ]~75[g / cm 2 ]), and the printing speed is 40 [ppm] per side. The temperature of the heating roller 51 when printing the print patterns of Figures 8(a) and (b) is approximately 160 [°C]. The print patterns are printed in an environment with a temperature of 22 [°C] and a humidity of 50 [%], and the voltage values ​​(DC voltages) applied to each roller at that time are adjusted to the following ranges:

[0060] Charging roller 18: -1050[V] Developing roller 12: -195[V] to -150[V] Supply roller 13: -285[V] to -240[V] Regulator blade 14: -285[V] to -240[V] Transfer roller 40: +2000[V]

[0061] Next, a method for determining the image fixability of a printed image will be described. After 50 sheets of the print pattern shown in FIG. 8(a) have been printed, the image fixability X1 [%] of the image on the first medium and the image fixability X2 [%] of the image on the 50th medium are measured after 15 minutes. 50 [%] and X1 [%] are measured. 50 The measurement of [%] was carried out by applying mending tape, which is an adhesive tape with an adhesive surface, to each of the areas F1, F2, and F3 shown in FIG. 8(a), then peeling off the mending tape, and measuring the average value of the ratio of density change before and after the tape application and peeling process using the mending tape for the areas F1, F2, and F3. Here, an image with a high image fixation rate (i.e., an image with excellent image fixation) is an image with a small change in density before and after the tape application and peeling process. The density of area F1 before the tape application and peeling process is defined as Y1 B The density after the tape application and peeling process is Y1 A The density of the area F2 before the tape peeling process is Y2 BThe density after the tape application and peeling process is Y2 A The density of the area F3 before the tape application and removal process is Y3 B The density after the tape application and peeling process is Y3 A Then, the image fixation rate X [%] is calculated by the following formula (2).

[0062]

number

[0063] The density was measured using a spectrophotometer (X-Rite eXact) manufactured by X-Rite Corp. The image fixability was evaluated according to the following criteria.

[0064] An image with a low image fixation rate is an image in which the solid area is left blank after the tape application and removal process, as shown in Figure 8(b). Figure 9 shows the results of the image fixation evaluation test in Table 1. Table 1 shows the image fixation rates X1 [%] and X2 [%] when the initial developer storage ratio P [%] is changed. 50 The trend in [%] is shown.

[0065] Image fixation rate X1 [%] of the image on the first sheet of media and image fixation rate X on the 50th sheet of media 50 [%], X1 [%] ≥ 80 and X 50 If X1 [%] ≥ 90, it is judged as "excellent" (in Figure 9, it is marked with a circle "〇"). 50 If [%] ≥ 90, it is judged as "good" (indicated by a triangle "△" in Figure 9). 50 If it is less than 90, it is judged as "bad" (in Figure 9, it is marked with a cross "x").

[0066] 2-2 Image Fixation Evaluation Method 1 Table 1 in FIG. 9 shows the image fixing rates X1 [%] and X2 [%] when the initial developer storage ratio P [%] is changed. 50 When P=20[%] and when P=30[%], the initial developer 21b in the storage section 15 is replaced with the replenishment developer 21a in the developer storage body 20 by the time 50 sheets are printed, so that a sufficiently good image fixability can be ensured.

[0067] In the cases of P=40[%], P=50[%], P=60[%], and P=70[%], the initial developer 21b in the storage portion 15 is not sufficiently replaced by the replenishment developer 21a in the developer storage body 20, and the image fixing rate X 50 is lower than 90[%]. In other words, the larger the initial developer accommodation ratio P[%], the worse the image fixability tends to be.

[0068] The initial developer storage ratio P [%] is preferably within the range of 20 [%] to 70 [%]. If P [%] is less than 20 [%], the amount of initial developer 21b is too small, causing blurring before the developer storage body 20 is mounted. If P [%] is greater than 70 [%], the amount of initial developer 21b is too large, causing particles of the initial developer 21b to fly out of the storage section 15 and contaminate the inside of the developing device 10. Therefore, the evaluation test of this embodiment was performed under the condition of an initial developer storage ratio P = 70 [%], which results in the poorest image fixation rate. This is because if there is no problem with P = 70 [%], it can be said that there is no problem in practical use.

[0069] Next, in order to solve the problem that the image fixing property deteriorates as the initial developer storage ratio P [%] increases, the glass transition temperature T g [℃] and softening point temperature T 1 / 2 Here, the initial developer filled in the containing portion 15 is designated as 21b, and the replenishment developer filled in the developer containing body 20 is designated as 21a. The glass transition temperature of the replenishment developer 21a filled in the developer containing body 20 is designated as T ga , the softening point temperature T 1 / 2a The glass transition temperature of the initial developer 21b stored in the storage section 15 is T gb , the softening point temperature T 1 / 2b Let's say.

[0070] In the conventional developing device, the glass transition temperature T gband softening point temperature T 1 / 2b The glass transition temperature T ga and softening point temperature T 1 / 2a are low. That is, T ga <T gb , T 1 / 2a <T 1 / 2b In other words, the replenishment developer 21a mounted in the replenishment developer accommodating body 20 is more soluble and fixable than the initial developer 21b filled in the accommodating portion 15.

[0071] Next, the glass transition temperature T gb and softening point temperature T 1 / 2b and the glass transition temperature T ga and softening point temperature T 1 / 2a The reason why the developer 21a and the developer storage body 20 are different from each other will be explained below. If the developer 21a to be supplied to the storage body 15 is stored in the storage section 15, horizontal streaks appearing at intervals corresponding to the period of the photosensitive drum 11 shown in FIG. 10(a) and horizontal streaks appearing at intervals corresponding to the period of the developing roller 12 shown in FIG. 10(b) may appear on the printed image after a long period of storage. This is because the developer 21 has adhered to the contact area between the photosensitive drum 11 and the developing roller 12 and the contact area between the regulating blade 14 and the developing roller 12 during the long period of storage. The glass transition temperature T g and softening point temperature T 1 / 2 If a developer with a low viscosity and that melts easily even at low temperatures (i.e., a developer with a low melting point) is used, there is a high risk that the developer 21 will melt if left unused for a long period of time and adhere to the developing roller 12 or the photosensitive drum 11. In other words, if the same developer is used for the initial developer 21b installed in the storage section 15 and the replenishment developer 21a installed in the developer storage body 20, it will be impossible to achieve both storage stability and image fixability, so different developers are used.

[0072] 11 shows the results of the evaluation test of image fixing property and storage stability in Table 2. Table 2 shows the results of the test of the initial developer 21b, which was adjusted to a glass transition temperature T g and softening point temperature T1 / 2 The results of checking the image fixing property and storage stability of the initial developer 21b with the amount of developer varied are included.

[0073] Glass transition temperature T g and softening point temperature T 1 / 2 Common methods for varying this include adjusting the content ratio of crystalline polyester resin and amorphous polyester resin in the binder resin of the developer, or selectively using amorphous and crystalline resins. Image fixation here is determined by the image fixation rate X1 of the first printed page using the evaluation method described above. This is because the developer container 20 is filled with the same developer 21, and the image fixation rate does not fluctuate even after printing 50 pages. A circle (◯) indicating a good result indicates an image fixation rate X1 [%] ≥ 90, and a cross (×) indicating a poor result indicates an image fixation rate X1 [%] < 90.

[0074] 2-2 Image Fixation Evaluation Method 2 The shelf life is judged by the state of streaks that appear on the printed image in halftone printing after leaving the developing device in an environment of 47°C temperature and 66% humidity for one month. If the developer has stuck and streaks appear in the cycle of the developing roller 12 or the photosensitive drum 11, it is marked with a cross "x" indicating a defect. As a result, T g ≦46[℃] and T 1 / 2 At temperatures below 125°C, an image fixation rate of 90% or more can be ensured. g ≧57[℃] and T 1 / 2 At temperatures above 137°C, no streaks due to developer adhesion occur after long-term storage. However, because there is no favorable range that simultaneously satisfies both image fixation and storage stability, different developers must be filled into the storage section 15 and the developer storage body 20. As mentioned above, if the initial developer storage ratio P exceeds 40%, it will take many prints to replace the initial developer 21b with a low image fixation rate installed in the storage section 15 with the replenishment developer 21a with a high image fixation rate filled in the cartridge. Solving this issue with a single developer alone is difficult.

[0075] Therefore, in this embodiment, the glass transition temperature T gand softening point temperature T 1 / 2 High-temperature developer (good storage stability) and glass transition temperature T g and softening point temperature T 1 / 2 Developers with low viscosity (good image fixability) are mixed using the method shown in Figures 12(a) to (c). First, an arbitrary weight of first developer A is placed in a 500 mL plastic bottle 171. Next, an arbitrary weight of second developer B is placed in the plastic bottle 171. (The order in which the first developer A and the second developer B are placed is not specified.) The lid 172 is closed, and the plastic bottle 171 is turned upside down to allow all the developers to fall out. This process is repeated six times. Next, the plastic bottle 171 is shaken ten times. In this way, the two types of developers are mixed to produce mixed developer 21ab.

[0076] Figure 13 shows the T gA = 46 [℃], T 1 / 2 = 125[℃] g = 57 [℃], T 1 / 2 The glass transition temperature T of the two developers was measured by varying the mixing ratio of the developer 21ab, which was prepared by mixing the second developer B, which had a glass transition temperature T = 137°C, with the developer 21ab prepared by the above method. The results of checking the image fixability and storage stability are shown in Table 3. g and softening point temperature T 1 / 2 From the results of Table 2 above, the lower limit at which the developer alone can satisfy the image fixing property is T g = 57 [℃], T 1 / 2 = 137[℃], the upper limit for the developer alone to satisfy storage stability is T g = 46 [℃], T 1 / 2 = 125[°C], these conditions are assumed to be the prerequisites for the developer to be mixed. The evaluation method and criteria for image fixation and storage stability are as described above (see Evaluation Method 1 for image fixation). As a result, the glass transition temperature T g and softening point temperature T 1 / 2 When two different developers are mixed, the glass transition temperature T g and softening point temperature T 1 / 2 A is a developer with a low glass transition temperature T g and softening point temperature T 1 / 2If the developer with the higher viscosity is designated as B, then the mixing ratio of the second developer B to the first developer A is in the range of 2:8 to 7:3, and the initial developer storage ratio is in the range of 20% to 70%. Here, the effect of the mixed developer 21ab will be explained with reference to Figures 14(a) to 14(c).

[0077] Figures 14(a) to 14(c) are schematic diagrams showing the dot arrangement of developer particles peeled off with mending tape after evaluation of image fixation rate. Figure 14(a) shows the results when a single developer, second developer B, which has poor image fixation properties, is used. Figure 14(b) shows the results when a mixed developer of first developer A and second developer B is used to improve image fixation. Figure 14(c) shows the results when the ratio of first developer A is further increased. In Figures 14(a) to 14(c), the black circle (●) indicates fixed second developer B, and the white circle (○) indicates unfixed second developer B peeled off using the mending tape. The black square (■) indicates fixed first developer A. In Figure 14(a), there are many developer particles that did not fix, but in Figure 14(b), the number of developer particles that did not fix is ​​reduced by mixing in a developer with high image fixation properties. In FIG. 14(c), the number of developer particles that could not be fixed is further reduced.

[0078] Similarly, Figures 15(a) to 15(c) are schematic diagrams showing the state of developer adhesion at the contact point between the photosensitive drum 11 and the developing roller 12 immediately before printing after a long period of use. Figures 15(a) to 15(c) assume that developer has adhered to the surface of the photosensitive drum 11. Adhesion to the developing roller 12 and the regulating blade 14 can also be explained using similar schematic diagrams, so their explanations are omitted. Figure 15(a) shows the case where a single developer, a conventional first developer A with poor storage stability, is used. Figure 15(b) shows the case where a mixed developer of first developer A and second developer B is used to improve storage stability. Figure 15(c) shows the case where an even larger amount of second developer B is used. The black circles (●) indicate particles of adhered first developer A. In Figure 15(a), there is a large amount of adhered first developer A, and if printing is performed in this state, noticeable streaks will occur on the printed image. In Figure 15(b), the second developer B is less likely to adhere, resulting in a state in which the adhered first developer A is sparsely present. In Figure 15(c), the amount of adhered first developer A is even less. In this state, even if printing is carried out as is, no noticeable streaks will appear on the printed image.

[0079] To summarize the results of this embodiment, it is possible to achieve both image fixation (an image fixation rate of 90% can be achieved within 50 sheets after the initial printing) and storage stability (no streaks due to developer adhesion when left unused for a long period of time) within the following favorable range.

[0080] Glass transition temperature T gb and softening point temperature T 1 / 2b The developer with a higher glass transition temperature T ga and softening point temperature T 1 / 2a The developer with the lowest T is designated as the first developer A. ga >T gb , T 1 / 2a >T 1 / 2b is.

[0081] Glass transition temperature T gIn the measurement, the thermal characteristics of the developer were measured by differential scanning calorimetry (DSC) using a thermal analyzer system "DSC6220" manufactured by Seiko Instruments Inc. As a result of the measurement, a characteristic curve was obtained. This characteristic curve showed an endothermic peak near 65°C, which indicates that a glass transition occurs near this temperature.

[0082] Softening point temperature T 1 / 2 In the measurement of the melting temperature T 1 / 2 Using a Shimadzu flow tester "CFT-500D," 1 g of pelletized developer was heated at a temperature increase rate of 3 °C / min from a starting temperature of 50.0 °C under a load of 10 kg and with a die hole diameter of 1 mm. The plunger descent distance of the flow tester was plotted against the temperature, and the temperature at which half of the developer (toner) flowed out was taken as the melting temperature (softening point temperature) T 1 / 2 It was decided.

[0083] The weight of the second developer B is W B The weight of the first developer A is W A When the weight ratio W B :W A The second developer B and the first developer A are mixed to prepare a mixed developer. The weight ratio Z of the second developer B in this mixed developer is B [%] is within the range of the following formula (3). 20≦Z B [%]≦70 (3)

[0084] The lower limit of 20% in formula (3) is the limit value at which good image fixing properties can be ensured, and the upper limit of 70% in formula (3) is the limit value at which good storage stability can be ensured.

[0085] Furthermore, equation (3) is W B :W A This means that it is desirable for the ratio to be in the range of 2:8 to 7:3.

[0086] 《2-3》Prerequisite C1 The glass transition temperature T of the second developer B gb [℃] and softening point temperature T 1 / 2b It is desirable that [°C] satisfy the following conditions (4) and (5). 57≦T gb [℃]≦60 (4) 137≦T 1 / 2b [℃]≦140 (5) The range of 57°C to 60°C shown in condition (4) is the glass transition temperature T g The range of 137°C to 140°C shown in condition (5) is the softening point temperature T 1 / 2 is the numerical range.

[0087] The glass transition temperature T of the first developer A ga [℃] and softening point temperature T 1 / 2a It is desirable that [°C] satisfy the following conditions (6) and (7). 43≦T ga [℃]≦46 (6) 123≦T 1 / 2a [℃]≦126 (7) The range of 43° C. to 46° C. shown in condition (6) is the glass transition temperature T of the first developer A alone so as not to impair its high storage stability. g The range of 123° C. to 126° C. shown in condition (7) is the softening point temperature T 1 / 2 is the numerical range.

[0088] As described above, the second developer B alone does not provide good fixability, while the first developer A alone does not provide high storage stability. Therefore, as in the present embodiment, by mixing the first developer A and the second developer B in the weight ratio described above, a developer that has both high storage stability and good fixability can be obtained. In particular, the glass transition temperature T gBy mixing two types of developers with different glass transition temperatures, it is possible to prevent the developers from flocculating together when left unused for a long period of time. Specifically, by interposing a second developer having a higher glass transition temperature than a first developer between the first and second developers, it is possible to prevent the first developers from flocculating together when left unused for a long period of time. More specifically, if the first difference obtained by subtracting the first glass transition temperature from the second glass transition temperature is 11°C or more and 17°C or less, it is possible to prevent the flocculation.

[0089] Therefore, the glass transition temperature T g and softening point temperature T 1 / 2 Instead of adjusting the glass transition temperature T g and softening point temperature T 1 / 2 After adjusting each of these, they are mixed within the above numerical ranges.

[0090] 《2-4》Prerequisite C2 It is desirable that the initial developer accommodation ratio P [%] satisfies the following formula (8). 20≦P[%]≦70 (8) The lower limit of 20% is the limit at which printing can be performed without blurring before the developer container 20 for developer replenishment is installed. The upper limit of 70% is the limit value that can be used to prevent developer particles from scattering from the container.

[0091] <3> Effects of the embodiment As explained above, the softening point temperature T 1 / 2A (or glass transition temperature T gA and ) a first developer A having a lower glass transition temperature T than the first developer A. gB and softening point temperature T 1 / 2By using the mixed developer obtained by mixing the first developer B with the second developer B having a higher viscosity as the initial developer 21b, even if the amount of initial developer in the storage section 15 of the developing device 10 (i.e., the initial storage amount) is large, it is possible to obtain the effect of ensuring good image fixation without requiring a large number of prints until the initial developer 21b in the developer storage body 20 is replaced with the replenishment developer 21a.

[0092] The initial developer 21b has a glass transition temperature T gB and softening point temperature T 1 / 2 Since the second developer B having a high viscosity is contained, high storage stability of the initial developer 21b can be ensured.

[0093] <4> Aspects of the present disclosure Various aspects of the present disclosure are summarized below as appendices. (Appendix 1) an image carrier (11) that carries an electrostatic latent image and is rotatable around a rotation axis; The first developer (A) and the second developer (B) have a softening point temperature (T 1 / 2 a storage section (15) that stores a developer (21b) mixed with a second developer (B) having a high color density; a developer carrier (12) for developing the electrostatic latent image with the developer (21b); and where a first weight ratio of the first developer (A) in the developer (21b) is α and a second weight ratio of the second developer (B) in the developer is 1-α, α is equal to or greater than 0.2 and less than 1; The weight percentage (P) of the weight (N) of the developer (21b) contained in the container (15) to the maximum weight (M) of the developer that can be contained in the container (15) is 20% or more. A developing device (10) characterized by: (Appendix 2) The developer container (20) further includes the developer (21b), The developer (21b) is supplied from the developer container (20) to the container (15). 2. The developing device (10) according to claim 1. (Appendix 3) The first weight ratio α is 0.2 or more and 0.7 or less. 3. The developing device (10) according to claim 1 or 2. (Appendix 4) The weight percentage (P) is 20% or more and 70% or less. 4. A developing device (10) according to any one of claims 1 to 3. (Appendix 5) The first glass transition temperature (T gA ) is between 43°C and 46°C, The second glass transition temperature (T gB ) is between 57°C and 60°C, 5. A developing device (10) according to any one of appendices 1 to 4. (Appendix 6) The first softening point temperature (T 1 / 2a ) is between 123°C and 126°C, The second softening point temperature (T 1 / 2b ) is between 137°C and 140°C. 6. A developing device (10) according to any one of appendices 1 to 5. (Appendix 7) The second glass transition temperature (T gB ) to the first glass transition temperature (T gA The first difference obtained by subtracting (a) is 11°C or more and 17°C or less. 6. The developing device (10) according to claim 5. (Appendix 8) The second softening point temperature (T 1 / 2b ) to the first softening point temperature (T 1 / 2a The second difference obtained by subtracting the temperature (°C) is 11°C or more and 17°C or less. 7. The developing device (10) according to claim 6. (Appendix 9) An image forming apparatus (1) having a developing device (10) according to any one of appendices 1 to 8. (Appendix 10) A developer container (20) is attached to a developing device (10) having a container (15) for containing a developer, and contains a developer (21b) to be supplied into the container (15), The developer (21b) has a softening point temperature (T 1 / 2 ) and a second developer (B) having a high where a first weight ratio of the first developer (A) in the developer (21b) is α and a second weight ratio of the second developer (B) in the developer (21b) is 1-α, α is equal to or greater than 0.2 and less than 1; The weight percentage (P) of the weight (N) of the developer (21b) contained in the container (15) to the maximum weight (M) of the developer that can be contained in the container (15) is 20% or more. A developer container (20) characterized by: (Appendix 11) a first developer (A) and a second developer (B) having a softening point temperature (T 1 / 2 a developer (21b) mixed with a second developer (B) having a high toner content, into a container (15) of a developing device (10), a first step of mixing the first developer (A) and the second developer (B) to produce the developer (21b) so that α is 0.2 or more and less than 1, where α is a weight ratio of the first developer (A) in the developer (21b) and 1-α is a weight ratio of the second developer (B) in the developer (21b); a second step of filling the developer (21b) into the storage portion (15) so that the weight percentage (P) of the developer (21b) is 20% or more with respect to the maximum weight (M) of the developer that can be stored in the storage portion (15); A developer filling method comprising at least the steps of: (Appendix 12) a first developer (A) and a second developer (B) having a softening point temperature (T 1 / 2a developer (21b) mixed with a second developer (B) having a high color density, into a developer container (20), a first step of mixing the first developer (A) and the second developer (B) to produce the developer (21b) so that α is 0.2 or more and less than 1, where α is a weight ratio of the first developer (A) in the developer (21b) and 1-α is a weight ratio of the second developer (B) in the developer (21b); a second step of filling the developer (21b) into the storage portion (15) so that the weight percentage (P) of the developer (21b) is 20% or more with respect to the maximum weight (M) of the developer that can be stored in the storage portion (15); A developer filling method comprising at least the steps of: [Explanation of symbols]

[0094] 1 image forming apparatus, 1a housing, 10 developing device, 11 photosensitive drum (image carrier), 12 developing roller (developer carrier), 13 supply roller, 14 regulating blade, 15 storage section, 16a, 16b, 16c stirring member, 18 charging roller, 20 developer storage body (toner cartridge), 21a replenishment developer, 21b initial developer, 40 transfer roller, 50 fixing device, 70 optical head, 80 medium, A first developer, B second developer, T 1 / 2 , T 1 / 2a , T 1 / 2b Softening point temperature, T g , T ga , T gb Glass transition temperature.

Claims

1. an image carrier that carries an electrostatic latent image and is rotatable around a rotation axis; a container for containing a developer in which a first developer and a second developer having a softening point higher than that of the first developer are mixed; a developer carrier that develops the electrostatic latent image with the developer; and where a first weight ratio of the first developer in the developer is α and a second weight ratio of the second developer in the developer is 1-α, α is equal to or greater than 0.2 and less than 1; The weight percentage of the weight of the developer contained in the container to the maximum weight of the developer that can be contained in the container is 20% or more. A developing device characterized by:

2. The developer container further includes a developer container for containing the developer. The developer is supplied from the developer container to the storage section.

2. The developing device according to claim 1.

3. The first weight ratio α is equal to or greater than 0.2 and equal to or less than 0.

7.

3. The developing device according to claim 1, wherein the developing device is a developing unit.

4. The weight percentage is 20% or more and 70% or less.

3. The developing device according to claim 1, wherein the developing device is a developing unit.

5. a first glass transition temperature of the first developer is 43° C. or higher and 46° C. or lower; a second glass transition temperature of the second developer is 57° C. or higher and 60° C. or lower; 3. The developing device according to claim 1, wherein the developing device is a developing unit.

6. a first softening point temperature of the first developer is 123° C. or higher and 126° C. or lower; a second softening point temperature of the second developer is 137° C. or higher and 140° C. or lower; 6. The developing device according to claim 5.

7. a first difference obtained by subtracting the first glass transition temperature from the second glass transition temperature is 11° C. or more and 17° C. or less; 6. The developing device according to claim 5.

8. a second difference obtained by subtracting the first softening point temperature from the second softening point temperature is 11° C. or more and 17° C. or less; 7. The developing device according to claim 6.

9. 3. An image forming apparatus comprising the developing device according to claim 1.

10. A developer container that is attached to a developing device having a container portion for accommodating a developer and that accommodates the developer to be supplied into the container portion, the developer is a mixture of a first developer and a second developer having a softening point higher than that of the first developer, where a first weight ratio of the first developer in the developer is α and a second weight ratio of the second developer in the developer is 1-α, α is equal to or greater than 0.2 and less than 1; The weight percentage of the weight of the developer contained in the container to the maximum weight of the developer that can be contained in the container is 20% or more. A developer container characterized by:

11. 1. A developer filling method for filling a developer containing a developer mixture of a first developer and a second developer having a softening point higher than that of the first developer into a container of a developing device, comprising: a first step of mixing the first developer and the second developer to produce the developer, where α is a weight ratio of the first developer in the developer and 1-α is a weight ratio of the second developer in the developer, so that α is 0.2 or more and less than 1; a second step of filling the developer into the container so that the developer accounts for 20% or more by weight of the maximum weight of the developer that can be contained in the container; A developer filling method comprising at least the steps of:

12. 1. A developer filling method for filling a developer accommodating container with a mixture of a first developer and a second developer having a softening point higher than that of the first developer, comprising: a first step of mixing the first developer and the second developer to produce the developer, where α is a weight ratio of the first developer in the developer and 1-α is a weight ratio of the second developer in the developer, so that α is 0.2 or more and less than 1; a second step of filling the developer into the container so that the developer accounts for 20% or more by weight of the maximum weight of the developer that can be contained in the container; A developer filling method comprising at least the steps of:

Images