Image forming apparatus

Abstract

To prevent the occurrence of fixing failure even when new toner is supplied to a developer container while toner remains in the container.SOLUTION: A storage member has an attachment part for determining the position of a container for supply having developer sealed therein and removably attaching the container. In a width direction of a recording material orthogonal to a conveyance direction of the recording material, with respect to the center of conveyance of the recording material, when one side is determined as a first area and the other side as a second area, the attachment part is arranged in the first area, and first temperature detection means is arranged in the second area.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to image forming apparatuses such as laser printers, copiers, and facsimiles.

Background Art

[0002] Generally, an electrophotographic image forming apparatus forms an image by transferring a developer image (toner image) formed on the surface of a photosensitive drum to a recording material as a transfer medium. And various developer supply methods have been proposed. As a supply method, a process cartridge is mentioned. In this process cartridge method, a photosensitive drum and a developer container are integrated, and when the developer runs out, the process cartridge is replaced with a new one. There is an advantage that maintenance can be easily performed by the user himself / herself.

[0003] On the other hand, a toner supply method of newly supplying toner to a developing device when the toner runs out is also known. Patent Document 1 discloses a method in which a toner supply container detachable from an image forming apparatus is provided, and when the toner supply container is attached to the image forming apparatus, toner is conveyed from the toner supply container to a developing container through a toner conveyance path provided with a conveyance screw. Further, Patent Document 2 discloses a method of attaching a toner supply container to an attachment port and supplying toner from the toner supply container to a developing container.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the toner supply method, when new toner is supplied while toner remains in the developing container, toners with different states are accommodated in the developing container. As a result, there was a risk that unevenness in the toner amount in the developed image would occur. Consequently, there was a risk that fixing failure would occur due to an increase in the toner amount.

[0006] The invention according to the present application has been made in view of the above situation, and an object thereof is to suppress the occurrence of fixing failure even when new toner is supplied while toner remains in the developing container.

Means for Solving the Problems

[0007] To achieve the above object, an image carrier, a developer carrier that develops an electrostatic latent image formed on the image carrier into an image with a developer, a frame body that supports the developer carrier and constitutes a housing member that houses the developer supplied to the developer carrier, a transfer means that transfers the developed image to a recording material, a fixing means that fixes the image to the recording material, a first temperature detection means that detects the temperature of the fixing means, and a control means that controls the supply of power to the fixing means based on the detection result by the first temperature detection means, are provided. The housing member can position and attach a supply container filled with a developer, has a supply port for supplying the developer of the attached supply container to the housing member, and when one side is defined as a first region and the other side is defined as a second region in the width direction of the recording material perpendicular to the conveyance direction of the recording material, with the conveyance center of the recording material as a reference, the supply port is only in the first region among the first region and the second region is arranged, and the first temperature detection means is only in the second region among the first region and the second region is arranged, which is characterized in that.

Effect of the Invention

[0008] According to the configuration of the present invention, it is possible to suppress the occurrence of fixing failure even when new toner is supplied while toner remains in the developing container.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments do not limit the invention of the claims, and not all combinations of the features described in the embodiments are essential for the solution means of the present invention.

Embodiment

[0011] [Overall Configuration of Image Forming Apparatus 1] FIG. 1(a) is a schematic configuration diagram of an image forming apparatus 1. The image forming apparatus 1 is a monochrome printer that forms a monochrome image on a recording material P based on image information input from an external device (not shown). The recording material P on which the image is formed includes, for example, paper such as plain paper and thick paper, plastic films such as sheets for overhead projectors, sheets with special shapes such as envelopes and index papers, and cloth. FIG. 1(a) shows the configuration of the image forming apparatus 1 viewed along the direction of the rotation axis of a photosensitive drum 21 described later. The vertical direction is a direction parallel to the vertical direction, and the horizontal direction is a direction parallel to the horizontal direction. Note that the rotation axes of a developing roller 31, a pair of discharge rollers 80, a pair of registration rollers 15, and a cover 83 described later are parallel to the rotation axis of the photosensitive drum 21.

[0012] As shown in FIGS. 1(a) and 2, the image forming apparatus 1 includes a printer main body 100 as a device main body and an operation unit 300 attached to the exterior surface of the printer main body 100. The printer main body 100 includes an image forming unit 10 that forms a toner image, which is an image, on a recording material P, and a feeding unit 60 that feeds the recording material P to the image forming unit 10. Further, the printer main body 100 includes a fixing device 70 that fixes the image formed by the image forming unit 10 onto the recording material P, and a pair of discharge rollers 80 that discharges the recording material P with the image fixed thereon outside the apparatus. The printer main body 100 also includes a control unit 360 for controlling the image forming operation on the recording material P by the image forming unit 10. The image forming unit 10 includes a scanner unit (not shown), an electrophotographic process cartridge 20, and a transfer roller 12 that transfers the image formed on a photosensitive drum 21 included in the process cartridge 20 onto the recording material P. The process cartridge 20 includes the photosensitive drum 21, a charging roller 22 disposed around the photosensitive drum 21, a pre-exposure device 23, and a developing device 30 including a developing roller 31.

[0013] The photosensitive drum 21 is a cylindrical photosensitive member. The photosensitive drum 21 of the present embodiment has a photosensitive layer formed of a negatively chargeable organic photosensitive material on a drum-shaped substrate formed of aluminum. Further, the photosensitive drum 21 as an image carrier is rotationally driven by a motor in a predetermined direction (clockwise in the figure) at a predetermined process speed.

[0014] The charging roller 22 contacts the photosensitive drum 21 with a predetermined pressure contact force to form a charging portion. Further, the charging roller 22 is applied with a desired charging voltage by a charging high-voltage power source to uniformly charge the surface of the photosensitive drum 21 to a predetermined potential. The photosensitive drum 21 of the present embodiment is charged to a negative polarity by the charging roller 22. The pre-exposure device 23 discharges the surface potential on the photosensitive drum 21 before it rotates and moves to the charging portion in order to cause stable discharge in the charging portion.

[0015] A scanner unit (not shown) as an exposure means exposes the surface of the photosensitive drum 21 by scanning the photosensitive drum 21 with a laser beam corresponding to image information input from an external device using a polygon mirror. By being exposed by the scanner unit, an electrostatic latent image corresponding to the image information is formed on the surface of the photosensitive drum 21. Note that the scanner unit is not limited to a laser scanner device, and for example, an LED exposure device having an LED array in which a plurality of LEDs are arranged along the longitudinal direction of the photosensitive drum 21 can also be used.

[0016] The developing device 30 includes a developing roller 31 as a developer carrier that carries a developer, a developing container 32 that serves as a frame of the developing device 30, and a supply roller 33 that can supply the developer to the developing roller 31. The developing roller 31 and the supply roller 33 are rotatably supported by the developing container 32. Further, the developing roller 31 is disposed at an opening of the developing container 32 so as to face the photosensitive drum 21. The supply roller 33 is rotatably in contact with the developing roller 31. The toner as the developer accommodated in the developing container 32 as an accommodating member is applied to the surface of the developing roller 31 by the supply roller 33. Note that a configuration that does not use the supply roller 33 may be employed as long as the developing roller 31 can be sufficiently supplied with toner.

[0017] The developing device 30 of the present embodiment uses a contact development method as a development method. That is, the toner layer carried on the developing roller 31 contacts the photosensitive drum 21 in a developing portion (developing region) where the photosensitive drum 21 and the developing roller 31 face each other. A developing voltage is applied to the developing roller 31 by a developing high-voltage power source. By applying the developing voltage, the toner carried on the developing roller 31 transfers from the developing roller 31 to the surface of the photosensitive drum 21 according to the potential distribution on the surface of the photosensitive drum 21, and the electrostatic latent image is developed as a toner image. Note that in the present embodiment, an inversion development method is employed. That is, after being charged in the charging step, toner adheres to the surface region of the photosensitive drum 21 where the charge amount has decayed by being exposed in the exposure step, thereby forming a toner image.

[0018] The toner of this embodiment has a normal charging polarity with a specific gravity of 1.1 and a negative polarity. The toner particle size is distributed with a width of about 4 to 8 μm, and the central particle size is 6 μm. As an example, the toner of this embodiment employs a polymerized toner generated by a polymerization method. Further, the toner of this embodiment does not contain a magnetic component and is a non-magnetic one-component developer in which the toner is applied to the developing roller 31 mainly by intermolecular forces and electrostatic forces (image forces). However, a one-component developer containing a magnetic component may also be used. In addition, the one-component developer may contain additives (for example, wax and silica fine particles) for adjusting the fluidity and charging performance of the toner in addition to the toner particles. Further, a two-component developer composed of a non-magnetic toner and a magnetic carrier may be used as the developer. When a magnetic developer is used, as the developer carrier, for example, a cylindrical developing sleeve with a magnet disposed inside is used.

[0019] The developing container 32 is provided with a housing portion 36 for housing the toner replenished from the toner pack 40 as a toner supply container, and a stirring member 34 as a stirring means disposed inside the housing portion 36. The stirring member 34 is driven by a motor (not shown) to rotate, thereby stirring the toner in the developing container 32 and feeding the toner toward the developing roller 31 and the supply roller 33. Further, the stirring member 34 has a role of circulating the toner peeled off from the developing roller 31 and not used for development in the developing container and making the toner in the developing container uniform. Note that the stirring member 34 is not limited to a rotating form. For example, a stirring member in a swinging form may be employed.

[0020] Further, at the opening of the developing container 32 where the developing roller 31 is disposed, a developing blade 35 for regulating the amount of toner carried on the developing roller 31 is disposed. The toner supplied to the surface of the developing roller 31 passes through the opposing portion with the developing blade 35 as the developing roller 31 rotates, thereby being uniformly thinned and charged negatively by triboelectrification.

[0021] As shown in Fig. 1(a), the feeding unit 60 includes a front door 61 that is supported by the printer main body 100 so as to be openable and closable, a tray unit 62, and a pickup roller 65 that can be lifted and lowered. The tray unit 62 constitutes the bottom surface of the recording medium storage space that appears when the front door 61 is opened. Note that the front door 61 closes the recording medium storage space in a state where it is closed with respect to the printer main body 100, and supports the recording medium P together with the tray unit 62 in a state where it is opened with respect to the printer main body 100.

[0022] The fixing device 70 of the present embodiment will be described below. The fixing device 70 of the present embodiment is a film heating type heating device aimed at shortening the startup time and reducing power consumption. A cross-sectional view showing an outline of the fixing device 70 in the present embodiment is shown in Fig. 3(a), and a schematic longitudinal view seen from the upstream side in the conveyance direction of the fixing device 70 is shown in Fig. 3(b). The fixing film 112 and the heater holder 130 are shown in a transparent state so that the state of the heater 113 can be easily understood.

[0023] The fixing device 70 of the present embodiment has a configuration in which a heater 113 including a resistance heating element and a substrate on which the heating element is disposed is held by a heater holder 130, and an endless belt, the fixing film 112, is provided around it. The heater holder 130 is preferably made of a material with a low heat capacity so as not to easily take away the heat of the heater 113. In this embodiment, a liquid crystal polymer (LCP), which is a heat-resistant resin, is used. The heater holder 130 is supported from the side opposite to the heater 113 by an iron stay 120 in order to give it strength. The stay 120 is pressurized by a pressure spring (not shown) from both longitudinal ends. As shown in Fig. 3(a), the heater 113 contacts the inner surface of the fixing film 112 to form an inner surface nip, and heats the fixing film 112 from the inside. A pressure roller 110 forms a fixing nip facing the heater 113 so as to sandwich the fixing film 112.

[0024] The pressure roller 110 receives the force of the pressure spring by bearings (not shown) provided at both ends of its core metal 117, and is driven by receiving a driving force from a driving source (not shown) by a driving gear 131 provided at the end of the core metal 117. When the pressure roller 110 is driven, the fixing film 112 is driven to rotate passively by receiving the driving force from the pressure roller 110 at the fixing nip. The fixing film 112 may be offset to either the left or right in the longitudinal direction of the heater 113. Therefore, as shown in FIG. 3(b), fixing flanges 150 for restricting the offset are arranged at both ends of the fixing film 112. The fixing flanges 150 are fitted and fixedly installed on the stay 120. The fixing film 112 is supported from the inner surface at both ends by the fixing flanges 150.

[0025] The fixing film 112 of this embodiment has an outer diameter of 20 mm in a cylindrical state that is not deformed, and has a multilayer structure in the thickness direction of the film. The fixing film 112 includes, as a layer structure, a base layer 126 for maintaining the strength of the film, a conductive primer layer 127, and a release layer 128 for reducing the adhesion of dirt to the surface. The base layer 126 requires heat resistance to receive the heat of the heater 113, and also requires strength to slide with the heater 113. Therefore, it is preferable to use a metal such as SUS (Stainless Used Steel), nickel, or a heat-resistant resin such as polyimide as the material of the base layer 126. Since the metal is stronger than the resin, it can be made thinner, and since the thermal conductivity is also high, it is easy to transfer the heat of the heater 113 to the surface of the fixing film 112. On the other hand, the resin has the advantage that it has a small specific gravity compared to the metal, so it has a small heat capacity and is easy to warm up. In addition, since the resin can be formed into a thin film by coating molding, it can be formed at low cost.

[0026] In this embodiment, the material of the base layer 126 of the fixing film 112 is a polyimide resin. Also, a carbon-based filler is added to improve the thermal conductivity and strength. The thinner the thickness of the base layer 126, the easier it is to transfer the heat of the heater 113 to the surface of the fixing film 112. However, if it is made thinner, the strength will decrease. Therefore, considering the balance between thermal conductivity and strength, about 15 μm to 100 μm is preferable, and it is set to 60 μm in this embodiment. The conductive primer layer 127 is made of a polyimide resin or a fluororesin, and carbon or the like is added to reduce the resistance. In the state where the recording material P is being conveyed through the fixing nip, the potential of the fixing film 112 is stabilized by grounding the exposed portion of the conductive layer.

[0027] As the material of the release layer 128, it is preferable to use a fluororesin such as perfluoroalkoxy resin (PFA), polytetrafluoroethylene resin (PTFE), or tetrafluoroethylene-hexafluoropropylene resin (FEP). In this embodiment, among the fluororesins, PFA, which is excellent in releasability and heat resistance, is used, and a conductive material is dispersed to make the resistance medium. The release layer 128 may be formed by coating a tube, or may be formed by coating the surface with a paint. In this embodiment, the release layer 128 is formed by a coating excellent in thin-wall molding. The thinner the release layer 128, the easier it is to transfer the heat of the heater 113 to the surface of the fixing film 112. However, if it is too thin, the durability will decrease. Therefore, considering the balance, about 5 μm to 30 μm is preferable, and it is set to 10 μm in this embodiment.

[0028] The pressure roller 110 of this embodiment has an outer diameter of 14 mm. An elastic layer 116 with a thickness of 2.5 mm of silicone rubber is formed on a portion of the iron core metal 117 with an outer diameter of 9 mm. The elastic layer 116 is made of heat-resistant silicone rubber or fluororubber, and silicone rubber is used in this embodiment. The outer diameter of the pressure roller 110 is about 10 to 50 mm. A smaller outer diameter can suppress the heat capacity, but if it is too small, the width of the fixing nip will become narrow, so an appropriate diameter is required. In view of the balance, the outer diameter of the pressure roller 110 is set to 14 mm in this embodiment. Regarding the thickness of the elastic layer 116, if it is too thin, heat will escape to the metal core, so an appropriate thickness is required. In view of the balance, the thickness of the elastic layer 116 is set to 2.5 mm in this embodiment.

[0029] A release layer 118 made of perfluoroalkoxy resin (PFA) is formed on the elastic layer 116. The release layer 118, similar to the release layer 128 of the fixing film 112, can be either a coated tube or a surface-coated paint. In this embodiment, a tube with excellent durability is used with a film thickness of 20 μm. As the material of the release layer 118, in addition to PFA, fluororesins such as PTFE and FEP, or fluororubbers and silicone rubbers with good release properties can also be used. The lower the surface hardness of the pressure roller 110, the wider the width of the fixing nip can be obtained with a light pressure, but if it is too low, the durability will decrease. Therefore, in view of the balance, the Asker-C hardness (600 g load) is set to 40° in this embodiment. The pressure roller 110 rotates at a surface moving speed of 150 mm / sec.

[0030] The heater 113 of this embodiment is a general heater used in a film heating type heating device, and resistance heating elements are arranged in series on a substrate made of ceramics. The heater 113 is formed by screen-printing an Ag / Pd (silver palladium) resistance heating element with a height of 10 μm on the surface of an alumina substrate with a width of 6 mm and a thickness of 1 mm, and covering it with glass with a thickness of 50 μm as a heating element protection layer. As shown in FIG. 3(b), a temperature detection element (thermistor) 115 for detecting the temperature of the ceramic substrate is arranged on the back side of the surface on which the resistance heating element of the heater 113 is arranged. The power supplied to the resistance heating element is controlled by controlling the target temperature according to the signal of the temperature detection element 115. The fixing temperature by the heater 113 is 180 °C for plain paper in this embodiment.

[0031] Also, on the surface of the heater 113 where the temperature detection element 115 is arranged, a temperature fuse (not shown), which is a safety element for cutting off the power supplied to the heater 113 when the heater 113 abnormally generates heat, is arranged. The heater 113 is connected to a commercial power supply via the temperature fuse. When the heater 113 abnormally generates heat and becomes high temperature, the temperature fuse blows and the power supply from the commercial power supply to the heater 113 is cut off.

[0032] [Image forming operation] Next, the image forming operation of the image forming apparatus 1 will be described. When an image forming command is input from an external device (not shown), an image forming process by the image forming unit 10 is started based on the image information input from the external device. A scanner unit (not shown) irradiates laser light toward the photosensitive drum 21 based on the input image information. The photosensitive drum 21 is charged by a charging roller 22, and an electrostatic latent image is formed on the photosensitive drum 21 by the irradiation of the laser light. The electrostatic latent image formed on the photosensitive drum 21 is developed as an image with toner by a developing roller 31.

[0033] In parallel with the image forming process, the pickup roller 65 of the paper feeding unit 60 feeds the recording material P stacked on the front door 61 and the tray unit 62. The recording material P is conveyed by the pickup roller 65 to the registration roller pair 15, and the skew is corrected by hitting the nip of the registration roller pair 15. Then, the registration roller pair 15 conveys the recording material P toward the transfer nip formed by the transfer roller 12 and the photosensitive drum 21 in accordance with the transfer timing of the image formed on the photosensitive drum 21.

[0034] The transfer roller 12 as a transfer means transfers the image formed on the photosensitive drum 21 to the recording material P by applying a transfer voltage from a transfer high-voltage power source. The recording material P onto which the image has been transferred is conveyed to the fixing device 70. When being conveyed through the fixing nip of the fixing device 70, it is heated and pressurized. As a result, the toner particles melt and then adhere, so that the image is fixed on the recording material P. The recording material P that has passed through the fixing device 70 is discharged by the discharge roller pair 80 as a discharge means. The recording material P is discharged to the outside (outside the machine) of the image forming apparatus 1 through the discharge port 85 and stacked on the discharge tray 81 arranged above the printer main body 100.

[0035] [Toner Supply from the Toner Pack to the Developing Device] Next, the toner supply from the toner pack 40 to the developing device 30 will be described. The toner pack 40 as a supply container for accommodating toner is configured to be detachable from the attachment port of the image forming apparatus 1. As shown in FIG. 1(b), the toner pack 40 includes an attachment portion 510 and a pouch 503. The pouch 503 is a flexible container capable of accommodating toner.

[0036] The developing device 30 is provided with a supply port 32a which is an attachment portion capable of attaching the attachment portion 510 of the toner pack 40. The supply port 32a is located on the inner side of the main body rather than the exterior of the image forming apparatus 1, and toner is supplied to the developing container 32 of the developing device 30 through the supply port 32a. The supply port 32a can detachably position the toner pack 40.

[0037] When mounting the toner pack 40 on the image forming apparatus 1, the user exposes the supply port 32a by moving and opening the cover 83. As shown in Fig. 1(a), the cover 83 is configured to be movable between a first position (broken line) that covers the inside of the image forming apparatus and a second position (solid line) that enables external access to the inside of the image forming apparatus. Note that the first position is a position that covers the supply port 32a and makes it impossible to access the supply port 32a from the outside, and the second position is a position that opens the supply port 32a and enables access to the supply port 32a from the outside. When the cover 83 moves to the second position, the user can mount the toner pack 40 on the supply port 32a. Alternatively, the toner pack 40 can be removed from the supply port 32a. The cover 83 as an opening / closing member rotates around the hinge on the left side of the cover 83, but is not limited to this configuration. For example, a slide-type door may be used. Also, a double-opening door (butterfly door) having hinges on each of the opposing sides of the opening of the image forming apparatus main body formed by the opening of the cover 83 may be used. Various opening / closing configurations can be applied to the cover 83.

[0038] As shown in Fig. 1(a), when the toner pack 40 is attached to the supply port 32a with the cover 83 moved to the second position, toner is supplied from the toner pack 40 to the developing container 32 of the developing device 30. More specifically, when the toner pack 40 is attached to the supply port 32a, the toner pack 40 and the developing container 32 communicate with each other, and the toner enclosed in the toner pack 40 moves to the developing container 32 by its own weight or the operation of the user pressing the toner pack 40.

[0039] Furthermore, as shown in Fig. 1(a), in a state where the toner pack 40 is attached to the supply port 32a, the upper part of the toner pack 40 in the direction of gravity protrudes outside (upper side in the direction of gravity) the exterior of the image forming apparatus main body. Thereby, it is not necessary to entirely accommodate the toner pack 40 inside the image forming apparatus, and the size of the image forming apparatus can be reduced. Also, the supply port 32a is arranged at a position that does not block the optical path of the laser light irradiated from a scanner unit (not shown).

[0040] [Features of Toner] The toner contained in the developing container 32 has a particle size distribution, and the toner with a smaller particle size is applied to the developing roller 31. This is because the toner with a smaller particle size is more easily affected by intermolecular forces and electrostatic forces (image force) with the developing roller 31. Therefore, the toner contained in the developing container 32 tends to be used starting from the toner with a smaller particle size, leaving behind the toner with a larger particle size.

[0041] Also, the toner applied to the developing roller 31 is regulated to have a predetermined charge amount by passing through the opposing part with the developing blade 35 as the developing roller 31 rotates. Since the toner with a smaller particle size has a larger surface area per unit weight compared to the larger toner, the charge amount becomes larger. Therefore, the amount of toner applied to the developing roller 31 is larger for the toner with a larger particle size than for the toner with a smaller particle size.

[0042] From the above, when image formation is performed and the toner contained in the developing container 32 is used, the developing container 32 will have more toner with a relatively larger particle size. When the amount of toner with a larger particle size increases in this way, the amount of toner applied to the developing roller 31 tends to gradually increase compared to the initial stage. When the amount of toner applied to the developing roller 31 increases, even if an electrostatic latent image corresponding to the same density is formed on the photosensitive drum 21, the amount of toner developing the electrostatic latent image also increases when the amount of toner applied to the developing roller 31 increases.

[0043] [State of Toner at Toner Refill] Next, FIG. 4 shows the flow of toner when new toner is replenished from the toner pack 40 into the developing container 32. FIG. 4(a) is a view of the developing container 32 seen from the same direction as FIG. 1(a). The toner replenished from the toner pack 40 is carried in the direction of the developing roller 31 by the agitation spring 34 when it enters the developing container 32.

[0044] FIG. 4(b) is a view of the developing container 32 as seen from the direction of arrow X in FIG. 1(a). The toner supplied from the toner pack 40 accumulates immediately below the supply port 32a. As the agitation spring 34 rotates, the toner is leveled little by little and moves in the width direction of the recording material P, which is a direction orthogonal to the conveyance direction of the recording material P. However, immediately after the toner is supplied, it is difficult for the supplied toner to move to the vicinity of position Z, which is far in the width direction from the supply port 32a.

[0045] An example of the toner particle size distribution immediately after the toner is supplied is shown in FIG. 4(c). Note that the particle size distribution in FIG. 4(c) is normalized. The particle size distribution width in the vicinity of position Z is about 6 to 8 μm. This is because, in the image formation before the supply, the toner with relatively small particle size was used for development, so relatively large-particle-size toner remains in the vicinity of position Z. On the other hand, the particle size distribution width in the vicinity of position Y, which is immediately below the supply port 32a, is about 4 to 8 μm. This is because the supply of new toner has increased the amount of toner with a smaller particle size than in the vicinity of position Z. Therefore, when developing the electrostatic latent image formed on the photosensitive drum 21 in such a state, even if the density is the same, the image with a larger amount of toner deposited will be formed in the vicinity of position Z than in the vicinity of position Y relatively.

[0046] [Fixing Temperature Control] The fixing device 70 detects the temperature of the heater 113 with the temperature detection element 115 and performs feedback control to maintain the fixing temperature at a predetermined target temperature. As described above, when the amount of toner changes, the amount of heat taken away from the fixing device 70 when fixing the image formed on the recording material P also changes. Therefore, by detecting the temperature of the heater 113 with the temperature detection element 115 and performing feedback control to maintain the fixing temperature at the target temperature even when the amount of toner changes, fixing defects can be suppressed.

[0047] In this embodiment, the relationship between the arrangement of the supply port 32a and the temperature detection element 115 of the fixing device 70 is as shown in FIG. 5. That is, when one region is defined as the first region and the other region is defined as the second region in the width direction of the recording material P with the conveyance center C in the width direction of the recording material P in FIG. 5 as the boundary, the supply port 32a is arranged in the first region. The temperature detection element 115 is arranged in a second region different from the first region. Note that the conveyance center C in the width direction of the recording material P is the central portion of the width restricting members 500a and 500b that restrict the width direction of the recording material P loaded on the front door 61 and the tray portion 62. That is, in a state where the recording material P is defined, in the width direction of the recording material P, the conveyance center C is at the same distance from both of the width restricting members 500a and 500b.

[0048] Here, as an example, the regions are divided based on the conveyance center C in the width direction of the recording material P, but it is not limited to this. For example, the regions may be divided based on the center in the longitudinal direction of the heater 113. Also in this case, when one region is defined as the third region and the other region is defined as the fourth region in the longitudinal direction of the heater 113, the supply port 32a is arranged in the third region, and the temperature detection element 115 is arranged in a fourth region different from the third region. In this case, the conveyance center C in the width direction of the recording material P and the center in the longitudinal direction of the heater do not necessarily have to coincide. As long as the supply port 32a is arranged in one region and the temperature detection element 115 is arranged in the other region.

[0049] Therefore, for example, the regions may be divided based on the center in the longitudinal direction of the resistance heating element included in the heater 113. Also in this case, when one region is defined as the fifth region and the other region is defined as the sixth region in the longitudinal direction of the resistance heating element, the supply port 32a is arranged in the fifth region, and the temperature detection element 115 is arranged in a sixth region different from the fifth region. In this case, the conveyance center C in the width direction of the recording material P and the center in the longitudinal direction of the resistance heating element do not necessarily have to coincide. As long as the supply port 32a is arranged in one region and the temperature detection element 115 is arranged in the other region.

[0050] Further, for example, it can also be represented by the distance from the outer wall (side wall) 600a and the outer wall (side wall) 600b of the image forming apparatus 1. In the longitudinal direction of the heater 113, when one side of the image forming apparatus 1 is defined as the first outer wall and the other side is defined as the second outer wall, the supply port 32a is disposed at a position closer to the second outer wall than the first outer wall, and the temperature detection element 115 is disposed at a position farther from the first outer wall than the second outer wall.

[0051] The reason why the supply port 32a and the temperature detection element 115 are preferably arranged at different positions in the first direction, which is the width direction of the recording material P or the longitudinal direction of the heater 113, will be described. As described with reference to FIG. 4 above, when toner is supplied from the toner pack 40, in the first direction, at a position relatively far from the supply port 32a, the ratio of the toner accommodated in the developing container 32 before supply, that is, the ratio of the toner having a large particle size, increases. As described above, when the amount of toner having a large particle size increases, the amount of toner carried also increases, and the temperature required for fixing also rises. By arranging the temperature detection element 115 in a region where the temperature required for fixing may rise, it is possible to suppress the occurrence of fixing defects by performing feedback control even for temporary unevenness in the amount of toner carried after supply.

[0052] [Effects of the present embodiment] As a comparative example, in a configuration in which the temperature detection element 115 is arranged in the same region as the supply port 32a when the conveyance center C of the recording material P is used as a reference in the first direction, the fixability after toner supply was evaluated.

[0053] The filling amount of the initial toner accommodated in the developing container 32 was set to 100 g, and image formation was performed at a printing rate of 4%. When the amount of toner accommodated in the developing container 32 reached 70 g, 50 g, and 30 g, 30 g of toner was supplied from the supply port 32a, respectively. Immediately after the supply, the following evaluation of the fixability was carried out.

[0054] The fixability evaluation was conducted in a low-temperature and low-humidity environment (temperature: 15 °C, humidity: 10%) where the toner cools down and the influence of the toner loading amount is likely to occur. As the recording material used for the evaluation, Xerox Vitality MultiPurPose PaPer (Letter size, 20 lb) left in the low-temperature and low-humidity environment for 2 days was used. The evaluation image was a full-page printing pattern, and 20 sheets were continuously passed through. After passing 20 sheets, those with no problem in fixability were marked as ○, and those with toner peeling even on one sheet were marked as ×. The evaluation results are shown in Fig. 6(a). Also, the toner loading amount per unit area on each recording material before replenishment is shown in Fig. 6(b).

[0055] As shown in Fig. 6(a), in the configuration of this embodiment, the temperature detection element 115 is arranged in a region where the toner loading amount on the recording material P may increase, and the fixing temperature is controlled according to the temperature detection result of the temperature detection element 115. Therefore, no fixing failure occurred.

[0056] On the other hand, in the comparative example, when the toner amounts stored in the developing container 32 were 70 g and 50 g, no fixing failure occurred. However, when the toner amount stored in the developing container 32 was 30 g, slight toner peeling was observed when forming images on the first and second sheets. This is because when the toner amounts stored in the developing container 32 were 70 g and 50 g, even when new toner was replenished, the unevenness of the toner loading amount in the first direction did not increase much. Therefore, even when the fixing temperature was controlled with the configuration of the comparative example, no fixing failure occurred. However, when the toner amount stored in the developing container 32 was 30 g, the unevenness of the toner loading amount due to replenishing new toner increased. When the fixing temperature was controlled with the configuration of the comparative example, a fixing failure occurred. In the comparative example, since the temperature detection element 115 is arranged in the same region as the replenishment port 32a, when new toner is replenished, the temperature of the region with a relatively low toner loading amount is detected and the fixing temperature is controlled. Therefore, in the region where the toner loading amount relatively increases, the amount of heat for melting the toner is insufficient, and toner peeling occurs.

[0057] In this way, by making the region where the supply port 32a is arranged different from the region where the temperature detection element 115 is arranged in the first direction, fixing failure can be suppressed.

Embodiment

[0058] In this embodiment, a configuration having temperature detection elements 115b and 115c, which are sub-thermistors used for end temperature rise control, in addition to the temperature detection element 115a, which is the main thermistor, will be described. Note that for the same configurations as those in the previous first embodiment, such as an image forming apparatus, detailed descriptions will be omitted in this embodiment.

[0059] FIG. 7 is a diagram showing the configuration of the fixing device in this embodiment. As shown in FIG. 7, in addition to the temperature detection element 115a as the first temperature detection means, temperature detection elements 115b as the second temperature detection means and 115c as the third temperature detection means are arranged on the back surface of the heater 113. The temperature detection element 115a is the same as the temperature detection element 115 described in the previous first embodiment, and is a main thermistor for detecting the temperature of the heater 113 and feeding back for controlling the fixing temperature.

[0060] On the other hand, the temperature detection elements 115b and 115c are arranged at both ends in the first direction which is the longitudinal direction of the heater 113. This is to detect that the ends of the heater 113 are heated up when fixing a recording material P with a short width. The resistance heating element of the heater 113 has a length that can fix even the recording material P with the maximum width among the recording materials P through which paper can pass. Therefore, when fixing a recording material with a width shorter than the maximum width, in the area where the recording material P does not pass, the recording material P is not deprived of heat, so the temperature in the area where the recording material P does not pass rises. The temperature detection elements 115b and 115c are arranged at positions where they can detect the temperature in the area that becomes the area where the recording material P does not pass depending on the width of the recording material P. When the detection results by the temperature detection elements 115b and 115c become higher than a predetermined temperature, it is determined that end heating has occurred. Then, control is performed to reduce the throughput by increasing the conveyance interval of the recording material to eliminate the end heating.

[0061] [Fixing Temperature Control] As shown in FIG. 7(b), also in this embodiment, in the first direction, the area where the supply port 32a is arranged is different from the area where the temperature detection element 115a is arranged. Therefore, when toner is supplied from the toner pack 40, in the first direction, at a position relatively far from the supply port 32a, the ratio of the toner contained in the developing container 32 before supply, that is, the ratio of the toner with a large particle size increases. As described above, when the amount of toner with a large particle size increases, the amount of toner loaded also increases, and the temperature required for fixing also rises. By arranging the temperature detection element 115a in the area where the temperature required for fixing may rise in this way, it is possible to suppress the occurrence of fixing defects by performing feedback control even for the temporary unevenness in the loading amount after supply.

[0062] [Effects of this Embodiment] Similar to the previous Example 1, the fixability was evaluated after replenishing the toner. Also in this example, the temperature detection element 115a is arranged in a region where the amount of toner loaded on the recording material P may increase, and the fixing temperature is controlled according to the temperature detection result of the temperature detection element 115a, so that fixing failure did not occur.

Example

[0063] In this example, the configuration of the heater 113 including the resistance heating elements with different lengths in the longitudinal direction will be described. Regarding the same configurations as in the previous Examples 1 and 2, such as the image formation values, detailed descriptions will be omitted in this example.

[0064] FIG. 8 is a diagram showing the configuration of the fixing device and the heater 113 in this example. As shown in FIG. 8(a), the three resistance heating elements arranged in the heater 113 in this example have different lengths in the longitudinal direction. The length of the longest first resistance heating element 700a is the arrow (A) in FIG. 8(a), the length of the second longest second resistance heating element 700b is the arrow (B), and the length of the shortest third resistance heating element 700c is the arrow (C).

[0065] Fixing is performed by switching the resistance heating element to which power is supplied according to the width of the recording material P on which the image is formed. The first resistance heating element corresponds to the case where the size of the recording material P is A4 or LTR, the second resistance heating element corresponds to the case where the size of the recording material P is B5 or EXE, and the third resistance heating element corresponds to the case where the size of the recording material P is A6 or 4×6. The temperature detection element 115 in this example is arranged inside the third resistance heating element as shown in FIG. 8(b) so that the detection result can be feedback-controlled to the fixing temperature in any case of fixing using any resistance heating element. That is, when viewed in the thickness direction of the heater 113, it can be said that the temperature detection element 115 is arranged at a position overlapping any of the resistance heating elements.

[0066] [Fixing Temperature Control] As shown in FIG. 8(c), also in the present embodiment, in the first direction, the region where the supply port 32a is disposed is different from the region where the temperature detection element 115 is disposed. Therefore, when toner is supplied from the toner pack 40, in the first direction, at a position relatively far from the supply port 32a, the ratio of the toner accommodated in the developing container 32 before supply, that is, the ratio of the toner having a large particle size increases. As described above, when the amount of toner having a large particle size increases, the amount of toner loaded also increases, and the temperature required for fixing also rises. By disposing the temperature detection element 115 in a region where the temperature required for fixing may rise, it is possible to suppress the occurrence of fixing defects by performing feedback control even for a temporary uneven load amount after supply.

[0067] Furthermore, the temperature detection element 115 is disposed inside the third resistance heating element so that the detection result can be feedback-controlled to the fixing temperature even when fixing is performed using any of the three resistance heating elements having different lengths in the longitudinal direction. Therefore, the occurrence of fixing defects can be suppressed regardless of which resistance heating element is used for fixing.

[0068] [Effects of the Present Example] Similar to the previous Examples 1 and 2, the fixability after toner supply was evaluated. Also in this example, since the temperature detection element 115 is disposed in a region where the amount of toner loaded on the recording material P may increase, and the fixing temperature is controlled according to the temperature detection result of the temperature detection element 115, no fixing defect occurred.

Explanation of Reference Numerals

[0069] 32a Supply port 113 Heater 115 Temperature detection element

Claims

1. An image carrier, A developer carrier that develops an electrostatic latent image formed on the image carrier into an image with a developer, A frame that supports the developer carrier and constitutes a housing member that houses the developer supplied to the developer carrier, Transfer means for transferring the developed image to a recording material, Fixing means for fixing the image on the recording material, First temperature detection means for detecting the temperature of the fixing means, Control means for controlling the supply of power to the fixing means based on the detection result by the first temperature detection means, comprising: The housing member can position and attach a supply container filled with a developer, and has a supply port for replenishing the developer in the attached supply container to the housing member. In the width direction of the recording material orthogonal to the conveyance direction of the recording material, when one side is defined as a first region and the other side is defined as a second region with reference to the conveyance center of the recording material, the supply port is disposed only in the first region of the first region and the second region, and the first temperature detection means is disposed only in the second region of the first region and the second region. An image forming apparatus characterized by this.

2. Second temperature detection means for detecting the temperature of the fixing means, Third temperature detection means for detecting the temperature of the fixing means, comprising: The image forming apparatus according to claim 1, wherein the second temperature detection means is disposed in the second region and the third temperature detection means is disposed in the first region.

3. The image forming apparatus according to claim 2, wherein the control means increases the conveyance interval of the recording material when the detection result by either one of the second temperature detection means and the third temperature detection means exceeds a predetermined temperature.

4. The fixing means includes a heater including a substrate on which a plurality of heating elements having different lengths in the width direction are arranged. The image forming apparatus according to any one of claims 1 to 3, wherein the first temperature detecting means is arranged at a position overlapping any of the plurality of heating elements when viewed in the thickness direction of the heater.

5. An image carrier; A developer carrier that develops an electrostatic latent image formed on the image carrier into an image with a developer; A frame body that supports the developer carrier and constitutes a housing member that houses the developer supplied to the developer carrier; Transfer means for transferring the developed image onto a recording material; Fixing means for fixing an image on a recording material, including a heater including a substrate on which a heating element is arranged; First temperature detecting means for detecting the temperature of the fixing means; Control means for controlling the supply of power to the fixing means based on the detection result by the first temperature detecting means. The housing member is capable of positioning and attaching a supply container filled with a developer, and has a supply port for supplying the developer of the attached supply container to the housing member. In the longitudinal direction of the heater, when one side is defined as a third region and the other side is defined as a fourth region with the center of the heater as a reference, the supply port is arranged only in the third region of the third region and the fourth region, and the first temperature detecting means is arranged only in the fourth region of the third region and the fourth region. The image forming apparatus is characterized by this.

6. Second temperature detecting means for detecting the temperature of the fixing means; Third temperature detecting means for detecting the temperature of the fixing means. The image forming apparatus according to claim 5, wherein the second temperature detecting means is arranged in the fourth region, and the third temperature detecting means is arranged in the third region.

7. When the detection result by either one of the second temperature detection means and the third temperature detection means exceeds a predetermined temperature, the control means lengthens the conveyance interval of the recording material. The image forming apparatus according to claim 6, characterized in that.

8. The fixing means includes a plurality of heating elements having different lengths in the longitudinal direction, The first temperature detection means is arranged at a position overlapping with any of the plurality of heating elements when viewed in the thickness direction of the heater. The image forming apparatus according to any one of claims 5 to 7, characterized in that.

9. An image carrier, A developer carrier that develops an electrostatic latent image formed on the image carrier into an image with a developer, A frame that supports the developer carrier and constitutes a housing member that houses the developer supplied to the developer carrier, Transfer means for transferring the developed image to a recording material, Fixing means for fixing an image on a recording material, including a heater having a substrate on which a heating element is arranged, First temperature detection means for detecting the temperature of the fixing means, Control means for controlling the supply of power to the fixing means based on the detection result by the first temperature detection means, The housing member can position and attach a supply container filled with a developer, and has a supply port for supplying the developer in the attached supply container to the housing member, When one side is a fifth region and the other side is a sixth region with the center of the heating element as a reference in the longitudinal direction of the heating element, the supply port is arranged only in the fifth region among the fifth region and the sixth region, and the first temperature detection means is arranged only in the sixth region among the fifth region and the sixth region. An image forming apparatus characterized by that.

10. Second temperature detection means for detecting the temperature of the fixing means, Third temperature detection means for detecting the temperature of the fixing means, The image forming apparatus according to claim 9, wherein the second temperature detecting means is disposed in the sixth region, and the third temperature detecting means is disposed in the fifth region.

11. The image forming apparatus according to claim 10, wherein the control means increases the conveyance interval of the recording material when the detection result by either one of the second temperature detecting means and the third temperature detecting means exceeds a predetermined temperature.

12. The fixing means includes a plurality of heating elements having different lengths in the longitudinal direction, The image forming apparatus according to any one of claims 9 to 11, wherein the first temperature detecting means is disposed at a position overlapping any of the plurality of heating elements when viewed in the thickness direction of the heater.

13. An image carrier, A developer carrier that develops an electrostatic latent image formed on the image carrier as an image with a developer, A frame that supports the developer carrier and constitutes a housing member that houses the developer supplied to the developer carrier, Transfer means for transferring the developed image to a recording material, Fixing means for fixing an image on a recording material, including a heater having a substrate on which a heating element is disposed, First temperature detecting means for detecting the temperature of the fixing means, An image forming apparatus comprising: control means for controlling the supply of power to the fixing means based on the detection result by the first temperature detecting means. The housing member is capable of positioning and attaching a supply container filled with a developer, and has a supply port for supplying the developer of the attached supply container to the housing member. In the longitudinal direction of the heater, when one side of the image forming apparatus is the first outer wall and the other side is the second outer wall, the supply port is disposed only at a position close to the second outer wall among the first outer wall and the second outer wall, and the first temperature detecting means is disposed only at a position close to the first outer wall among the first outer wall and the second outer wall. An image forming apparatus characterized by this.

14. A second temperature detecting means for detecting the temperature of the fixing means; A third temperature detecting means for detecting the temperature of the fixing means, and an image forming apparatus comprising: The second temperature detecting means is disposed at a position farther from the first outer wall than the second outer wall, and the third temperature detecting means is disposed at a position closer to the second outer wall than the first outer wall. The image forming apparatus according to claim 13, characterized in that

15. When the detection result by either one of the second temperature detecting means and the third temperature detecting means exceeds a predetermined temperature, the control means lengthens the conveyance interval of the recording material. The image forming apparatus according to claim 14, characterized in that

16. The fixing means includes a heater including a substrate on which a plurality of heating elements having different lengths in the longitudinal direction are disposed. The first temperature detecting means is disposed at a position overlapping any of the plurality of heating elements when viewed in the thickness direction of the heater. The image forming apparatus according to any one of claims 13 to 15, characterized in that

17. A cover movable between a first position that covers the supply port and makes access from the outside impossible and a second position that opens the supply port and enables access from the outside. When the supply container is attached to the supply port with the cover in the second position, the developer enclosed in the supply container can move to the storage member by its own weight. The image forming apparatus according to any one of claims 1 to 16, wherein the cover is movable from the second position to the first position in a state where the supply container is removed from the replenishment port.

Images