JP5172192B2 - Image forming unit and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming unit and an image forming apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a printer, a copying machine, a facsimile machine, or a multifunction machine, for example, an electrophotographic printer, an image forming unit, an LED head, a transfer roller, and the like are provided. In the image forming unit, the surface of the photosensitive drum uniformly and uniformly charged by the charging roller is exposed by the LED head to form an electrostatic latent image, which is accommodated in the image forming unit. The toner thus supplied is supplied to the surface of a developing roller as a developer carrying member by a toner supply roller, adhered to the electrostatic latent image, and developed to form a toner image. Subsequently, the toner image is transferred onto a sheet by a transfer roller and fixed by a fixing device, whereby an image is formed and printing is performed.

  By the way, in order to prevent the toner from leaking between the photosensitive drum and the casing of the image forming unit, a seal member is disposed inside the casing in contact with the developing roller.

The seal member includes a contact portion that is in contact with the developing roller, and a sponge sheet that is adhered to the back side of the contact portion, and the contact portion of the sponge sheet that is a free end contacts the developing roller. (For example, refer to Patent Document 1).
JP 2002-162828 A

  However, in the conventional image forming unit, for example, when the end of the seal member is bent inward and pressed by the developing roller, a gap is formed between the seal member and the developing roller. The toner may leak from the gap.

  Further, when the image forming unit is replaced or transported, an impact is given to the image forming unit in a state where the developing roller is not rotating and the seal member is in contact with the developing roller. Then, the toner may leak near the center of the seal member.

  The present invention provides an image forming unit and an image forming apparatus capable of solving the problems of the conventional image forming unit and improving the sealing state between the developer carrier and the housing of the image forming unit. The purpose is to provide.

  Therefore, in the image forming unit of the present invention, a housing and a developer carrier that is rotatably disposed in the housing, carries a developer, and develops a latent image formed on the image carrier. And a seal member that is disposed along the axial direction of the developer carrier and prevents the developer from leaking between the developer carrier and the housing.

  The seal member includes a sponge material disposed in contact with the developer carrier, and a surface area of a bottom surface larger than a surface area of an upper surface contacting the sponge material, and a surface area of the upper surface of the sponge material. A core having a larger trapezoidal shape and supporting the sponge material is provided.

  According to the present invention, in the image forming unit, the housing, and the developer carrier that is rotatably disposed in the housing, carries the developer, and develops the latent image formed on the image carrier. And a seal member that is disposed along the axial direction of the developer carrier and prevents the developer from leaking between the developer carrier and the housing.

  The seal member includes a sponge material disposed in contact with the developer carrier, and a surface area of a bottom surface larger than a surface area of an upper surface contacting the sponge material, and a surface area of the upper surface of the sponge material. A core having a larger trapezoidal shape and supporting the sponge material is provided.

  In this case, since the seal member includes a sponge material disposed in contact with the developer carrier, the developer carrier is pressed by the repulsive force. Therefore, since the developer carrying member and the sponge material are brought into close contact with each other, the sealing state between the developer carrying member and the housing of the image forming unit can be improved. As a result, the developer can be prevented from leaking between the developer carrying member and the sponge material. In addition, since the developer carrying member and the sponge material are not in contact with each other, the developer does not leak even when an impact is applied to the image forming unit when the image forming unit is replaced or conveyed. .

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this case, a printer as an image forming apparatus will be described.

  FIG. 2 is a schematic view of the printer according to the first embodiment of the present invention.

  As shown in the drawing, a paper feed cassette 11 serving as a medium accommodating portion for accommodating paper (not shown) as a medium is disposed in the lower part of the printer main body, that is, the apparatus main body, and is adjacent to the front end of the paper feed cassette 11. Thus, a paper feed mechanism for separating and feeding the paper one by one is provided. The paper feed mechanism includes paper feed rollers 12a and 12b, and the paper fed by the paper feed mechanism is sent to the transport roller unit 14 disposed at the top, and further sent to the transport roller unit 15. Thereafter, the transfer belt 17 serving as the transport member and the first transfer member is transported by the transfer belt 17 as the belt belt is driven by a belt motor (not shown) serving as a belt transport drive unit. It is allowed to pass between the forming units 22Bk, 22Y, 22M, and 22C and the transfer unit u1 as a transfer portion. The image forming units 22Bk, 22Y, 22M, and 22C and the transfer unit u1 constitute an image forming unit, and the image forming unit performs image formation for each color of black, yellow, magenta, and cyan.

  The transfer unit u1 includes a drive roller 27 as a first roller, a belt idle roller 28 as a second roller, and the transfer belt 17 stretched between the drive roller 27 and the belt idle roller 28. And a second transfer member disposed opposite to each of the photosensitive drums 52Bk, 52Y, 52M, and 52C as image carriers of the image forming units 22Bk, 22Y, 22M, and 22C with the transfer belt 17 interposed therebetween. Transfer rollers 51Bk, 51Y, 51M, and 51C are provided. The belt idle roller 28 applies tension so that the transfer belt 17 does not loosen.

  The transfer rollers 51Bk, 51Y, 51M, and 51C respectively generate toner images as developer images of the respective colors formed by the photosensitive drums 52Bk, 52Y, 52M, and 52C in the image forming units 22Bk, 22Y, 22M, and 22C. The toner image is transferred to the paper and a color toner image is formed.

  Subsequently, the paper is sent to a fixing device 18 as a fixing device, and a color toner image is fixed on the paper in the fixing device 18 to form a color image. The sheet sent from the fixing device 18 is conveyed by the conveying roller 19 and then discharged out of the apparatus main body by the discharge conveying roller 20. Reference numeral 31 denotes a discharge unit for discharging and depositing the paper sent from the fixing device 18 on the upper cover 23 disposed on the upper portion of the apparatus main body so as to be freely opened and closed.

  Then, in order to expose the surface of each of the photosensitive drums 52Bk, 52Y, 52M, and 52C to form an electrostatic latent image, each LED head 21Bk, 21Y, 21M, and 21C as an exposure device includes each image forming unit. The image forming units 22Bk, 22Y, 22M, and 22C are detachably disposed with respect to the apparatus main body. The LED heads 21Bk, 21Y, 21M, and 21C are held by the upper cover 23.

  The fixing device 18 is provided with a fixing roller 25 as a fixing member that is rotated by a fixing motor (not shown) as a fixing driving unit, and a pressure roller 26 as a pressure member that rotates with the fixing roller 25. Then, the toner as the developer is melted on the sheet by the heat from the heater 25a as the heating member disposed in the fixing roller 25.

  The fixing roller 25 is formed by coating an elastic body such as silicone rubber on a core metal such as iron or aluminum, and a surface of the elastic body is coated with a fluorine resin, and the toner is formed by the fluorine resin. Is prevented from sticking. The pressure roller 26 is formed by coating an elastic body such as silicone rubber on a core metal such as iron or aluminum, and the surface of the elastic body is coated with a fluorine resin, and the fluorine resin This prevents the toner of the toner image that has not been fixed from being offset and adhering to the fixing roller 25 when a paper jam occurs during conveyance of the paper.

  A fixing thermistor 30 serving as a fixing unit temperature detection unit is disposed opposite to the fixing roller 25, and the fixing roller 25 reaches a predetermined fixing temperature based on the temperature detected by the fixing thermistor 30. Thus, the heater 25a is intermittently controlled, that is, on / off controlled. In the present embodiment, an environmental thermistor 32 is provided as an external temperature acquisition unit that detects and acquires an environmental temperature outside the printer, that is, outside the apparatus, and as an environmental temperature detection unit. In the drawing, the environmental thermistor 32 is shown as being disposed in the paper feed mechanism, but in actuality, it is disposed in the immediate vicinity of the exterior member as the casing of the printer.

  Next, the image forming units 22Bk, 22Y, 22M, and 22C will be described. In this case, since the image forming units 22Bk, 22Y, 22M, and 22C have the same structure, the image forming unit 22Bk will be described, and the description of the image forming units 22Y, 22M, and 22C will be omitted.

  FIG. 3 is a conceptual diagram of the image forming unit according to the first embodiment of the present invention.

  As shown in the figure, the image forming unit 22Bk includes a charging roller 40Bk as a charging device that uniformly and uniformly charges the surface of the photosensitive drum 52Bk that rotates in the direction of the arrow, and a static image as a latent image. A developing roller 41Bk as a developer carrying member that develops an electrostatic latent image to form a toner image and a non-magnetic two-component toner 16 are accommodated, and the main body of the image forming unit 22Bk, that is, the image forming unit main body 50 A toner cartridge 42 as a developer accommodating member detachably disposed, and a developer supply member for supplying the toner 16 supplied from the toner cartridge 42 to the developing roller 41Bk and charging the toner 16 by friction. The sponge roller 43Bk is provided. Reference numeral 34 denotes a housing of the image forming unit main body 50.

  In the charging roller 40Bk and the developing roller 41Bk, a difference in peripheral speed, that is, a peripheral speed difference is formed by a gear reduction ratio (not shown) with respect to the photosensitive drum 52Bk. In the sponge roller 43Bk, the developing roller 41Bk The gears are rotated in the same direction by a gear (not shown) to form a peripheral speed difference.

  The developing roller 41Bk is made of urethane rubber, has an outer diameter of 16 [mm], is rotated at a linear speed of 155 [mm / sec], and is -200 [V] from a power source (not shown) during printing operation. A DC voltage is applied.

  Further, the toner 16 is made to have an average particle size of 5.5 [μm] by charging the resin, and is charged to a negative polarity. Reference numeral 47 denotes a sponge member as a seal member. The sponge member 47 includes a sponge material 45 as an elastic body and a core material 46 as a support, and is disposed below the casing 34 of the image forming unit 22Bk. The

  A developing blade 35 is pressed against the developing roller 41Bk to regulate the layer thickness of the toner 16 on the developing roller 41Bk, and 44 is pressed against the photosensitive drum 52Bk and remains on the photosensitive drum 52Bk after transfer. A cleaning blade 48 as a cleaning device for scraping off the toner 16 is scraped off by the cleaning blade 44, and the waste development formed in a part of the toner cartridge 42 to collect the collected waste toner as a waste developer. This is a waste toner reservoir as an agent storage unit.

  By the way, the toner 16 supplied from the toner cartridge 42 into the image forming unit main body 50 is accommodated in a developer accommodating space above the sponge roller 43Bk, and is agitated by an agitation bar (not shown) as an agitating member. 43Bk is supplied. Therefore, the space between the inner peripheral surface of the housing 34 and the developing roller 41Bk is sealed so that the toner 16 in the developer accommodating space does not leak out of the image forming unit main body 50.

  For this purpose, the sponge member 47 is disposed on the inner peripheral surface of the housing 34 so as to face the lower end of the developing roller 41Bk.

  The sponge member 47 has a hardness of 55 (Asker rubber hardness tester F type manufactured by Kobunshi Keiki Co., Ltd.) and a sponge rubber 45 made of silicone rubber having open cells with a cell diameter of 200 to 500 [μm]. And the core material 46 that supports the sponge material 45 and has a higher hardness than the sponge material 45, in the present embodiment, is formed of ABS resin containing glass fiber (for example, hardness 80). That is, the sponge material 45 is disposed in a portion of the sponge member 47 that contacts the developing roller 41Bk. In addition, the said glass fiber comprises a filler and ABS comprises base-material resin.

  The image forming unit 22Bk includes a housing 34, a photosensitive drum 52Bk, a charging roller 40Bk, a developing roller 41Bk, a developing blade 35, a sponge roller 43Bk, a stirring bar, a cleaning blade 44, and a sponge member 47.

  FIG. 1 is a cross-sectional view showing a main part of an image forming unit according to the first embodiment of the present invention, FIG. 4 is a perspective view showing an attached state of a sponge member according to the first embodiment of the present invention, and FIG. FIG. 6 is a first diagram showing the relationship between the developing roller and the sponge member in the first embodiment of the present invention, and FIG. 6 is a second diagram showing the relationship between the developing roller and the sponge member in the first embodiment of the present invention. FIG. 7 is a third view showing the relationship between the developing roller and the sponge member in the first embodiment of the present invention, and FIG. 8 is a sponge member at the time of non-printing in the first embodiment of the present invention. FIG. 9 is a diagram showing the state of the sponge member during printing in the first embodiment of the present invention, and FIG. 10 is a diagram for explaining the force applied to the developing roller in the first embodiment of the present invention. It is a figure to do.

  In FIG. 1, 16 is toner, 34 is a housing, 35 is a developing blade, 41Bk is a developing roller, 43Bk is a sponge roller, 45 is a sponge material, 46 is a core material, and 47 is a sponge member.

  As shown in FIG. 4, the sponge member 47 has a bottom surface at a plurality of locations in the width direction of the image forming unit main body 50 (axial direction of the developing roller 41 </ b> Bk). The casing 34 is fixed by a predetermined fixing element, in the present embodiment, by a screw bt. As shown in FIG. 1, the core material 46 has a trapezoidal cross section in the lateral direction, and the upper surface that contacts the sponge material 45 has a smaller surface area than the bottom surface. The sponge material 45 is adhered to the upper surface of the core material 46 by a predetermined adhesive along the developing roller 41Bk.

  In this case, since the surface area of the bottom surface of the core material 46 is increased, the core material 46 can be stably attached to the housing 34, and the surface area of the upper surface is decreased, so the sponge material for the developing roller 41Bk. The pressing force of 45 can be increased.

  As shown in FIG. 5, the sponge member 47 includes a contact point p1 between the outer peripheral surface of the developing roller 41Bk and the sponge material 45 and a midpoint p2 in the width direction of the upper surface of the sponge material 45, and the tangent line at the contact point p1. The tangent line k2 including the upper surface of the sponge material 45 and the tangent line k3 including the upper surface of the core material 46 are parallel to each other.

Further, as shown in FIGS. 6 and 7, the radius of the developing roller 41Bk is r, the thickness of the sponge material 45 when not in contact with the developing roller 41Bk is L1, and the developing roller 41Bk and the sponge material 45 are When the distance between the central axis sh1 of the developing roller 41Bk and the upper surface of the core material 46 when in contact is L2,
(R + L1-L2) / L1> 0
To be. Since the hardness of the sponge material 45 is lower than the hardness of the core material 46, the sponge material 45 is compressed by being sandwiched between the developing roller 41Bk and the core material 46, and the repulsive force acts on the inside of the developing roller 41Bk. Become.

  As a result, as shown in FIG. 8, the adhesion between the developing roller 41Bk and the sponge member 47 can be increased.

  FIG. 8 shows a state in which the developing roller 41Bk is not rotating during non-printing, for example, during conveyance in the image forming unit 22Bk. At this time, a repulsive force f1 is generated in the direction from the sponge member 47 toward the central axis sh1 of the developing roller 41Bk, that is, in the normal direction at the contact point p1 between the outer peripheral surface of the developing roller 41Bk and the sponge member 47. To press the developing roller 41Bk. Therefore, since the developing roller 41Bk and the sponge member 47 are in close contact with each other, the sealing state between the developing roller 41Bk and the housing 34 can be improved. As a result, the toner 16 does not leak from between the developing roller 41Bk and the sponge material 45. Further, since the developing roller 41Bk and the sponge member 47 are not in contact with each other, the toner 16 leaks even if an impact is applied to the image forming unit 22Bk when the image forming unit 22Bk is replaced or conveyed. There is no.

  9 and 10 show a state where the developing roller 41Bk is rotating during printing. At this time, a load f2 is applied to the portion of the sponge material 45 that is in contact with the developing roller 41Bk in the tangential direction by the rotation of the developing roller 41Bk. As described above, the sponge material 45 presses the developing roller 41Bk with the repulsive force f1 in the normal direction at the contact point p1, so that the resultant force f3 of the repulsive force f1 and the load f2, as shown in FIG. Will occur.

  Since the core member 46 is a rigid body and is fixed to the housing 34, the core member 46 is not deformed with the rotation of the developing roller 41Bk. Therefore, as shown in FIGS. 9 and 10, the resultant force f3 acts on the developing roller 41Bk as a repulsive force from the sponge material 45 to the developing roller 41Bk. As a result, the developing roller 41Bk and the sponge member 47 can be brought into close contact with each other, so that the toner 16 can be prevented from leaking in the direction of arrow E.

Further, since the developing roller 41Bk rotates while being pressed against the sponge material 45, untransferred toner that has not been transferred to the photosensitive drum 52Bk on the developing roller 41Bk is scraped off by the sponge material 45. The scraping of the untransferred toner is controlled by the pressure contact state of the sponge material 45 to the developing roller 41Bk. In this embodiment, the value of (r + L1-L2) / L1 is set as shown in FIGS.
(R + L1-L2) /L1=0.06
It was. By reducing this value (r + L1-L2) / L1, the amount of toner 16 scraped by the sponge material 45, that is, the toner amount can be reduced. As a result, new toner 16 is supplied to the developing roller 41Bk by the sponge roller 43Bk, and the toner 16 damaged by the developing blade 35, the toner 16 that is not normally charged, etc. are mixed with the new toner 16 and used for development. It will not be done. Therefore, a layer composed only of the new toner 16 is formed on the developing roller 41Bk, and stable transfer and development can be performed. As a result, the image quality can be improved.

  Next, the operation of the sponge material 45 will be described.

  FIG. 11 is a first diagram for explaining the operation of the sponge member in the first embodiment of the present invention, FIG. 12 is a second diagram for explaining the operation of the sponge member in the first embodiment of the present invention, FIG. 13 is a diagram for explaining an impact test method according to the first embodiment of the present invention.

  FIG. 11 is a diagram for explaining the difference in action due to the difference in hardness of the sponge material 45. When the hardness of the sponge material 45 is low and less than 30, for example, 25, the developing roller 41Bk is stopped. Represents the state of time. At this time, the pressing force f4 acts on the sponge material 45 in the direction of the arrow to prevent the toner 16 from leaking.

  However, since the sponge material 45 has a low hardness, it is easily deformed by an external force. In this case, when the toner 16 moves in the direction of the arrow H and tries to enter between the developing roller 41Bk and the sponge material 45, the sponge material 45 is deformed and the toner 16 easily enters. As a result, the toner 16 leaks.

  On the other hand, FIG. 12 shows a state where the hardness of the sponge material 45 is higher than 55, for example, 60, and the developing roller 41Bk is rotating in the arrow direction. At this time, since the sponge material 45 is not easily deformed, the sponge material 45 is hardly pulled in the direction of the arrow I by the rotation of the developing roller 41Bk. Therefore, since the sponge material 45 presses the developing roller 41Bk with the repulsive force f1, the toner 16 does not leak.

  However, when the hardness of the sponge material 45 is high, the toner 16 on the developing roller 41Bk may be rubbed and fixed to the surface of the developing roller 41Bk, the sponge material 45, or the like.

  Therefore, the hardness of the sponge material 45 was changed to evaluate the toner leakage and the toner fixing. Table 1 shows the evaluation results.

  The evaluation of toner leakage was carried out by an impact test using a method of 91 [cm] on one corner and three ridges. That is, in the image forming unit main body 50 in a state where the toner cartridge 42 is not attached, the image forming unit main body 50 filled with the toner 16 and the toner supply port sealed with a cover or the like is packed together with a cushioning material. The subject 61 is formed by packaging in a container. Subsequently, the subject 61 was dropped from a height of 91 [cm] with one apex angle down. A drop test was performed once to determine whether or not the toner 16 leaked from between the developing roller 41Bk and the sponge material 45.

  In this case, there was toner leakage when the hardness of the sponge material 45 was 25 or less. On the other hand, when the hardness of the sponge material 45 was higher than 25, there was no toner leakage.

The evaluation of toner adhesion is performed using standard paper (for example, weighing = 80 [g / m ² ], which is A4 size paper size) so that the back side of the side where the wrapping paper is opened becomes the printing side. Set in the printer) in the vertical direction (2 of the 4 sides are transported so that they are the front and rear edges in the transport direction) The distance from the trailing edge of one sheet to the leading edge of the next sheet is set to 60 [mm], and 0.3 [% duty] (printable range of one sheet of A4 size paper (288 [mm] ] × 200 [mm]), printing with an area ratio of 100 [%] is 100 [% duty], so 0.3 [% duty] is 0.86 [mm] × Represents a printing pattern of 200 [mm] horizontal line). The surface of the developing roller 41Bk and the sponge material 45 after printing is observed using a scanning electron microscope (acceleration voltage 15 [kV], magnification 500 to 1000 times). Judged.

  When the hardness of the sponge material 45 was 55 or less, the toner was not fixed on the surfaces of the developing roller 41Bk and the sponge material 45. On the other hand, when the hardness of the sponge material 45 is higher than 55, for example, in 60, the toner adheres to the surface of the developing roller 41Bk and the sponge material 45.

  From these, it can be seen that when the sponge material 45 has a hardness higher than 25 and lower than 55, there is no toner leakage.

  Next, a second embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st Embodiment, the same code | symbol is provided and the effect of the same embodiment is used about the effect of the invention by having the same structure.

  FIG. 14 is a cross-sectional view showing the main part of the image forming unit in the second embodiment of the present invention, and FIG. 15 is a diagram showing the structure in the side frame of the image forming unit in the second embodiment of the present invention. FIG. 16 is a front view of a spiral according to the second embodiment of the present invention.

  In this case, as shown in FIG. 14, in the rotation direction of the developing roller 41Bk, the toner 16 scraped off by the sponge member 47 on the upstream side from the position where the developing roller 41Bk and the sponge member 47 are in pressure contact, and The spiral 16 as a transport member for transporting and collecting the toner 16 leaking from the housing 34 as waste toner and collecting the toner 16 and the transported toner 16 do not leak out of the image forming unit 22Bk. A sealing material 72 is disposed. For this purpose, a bracket Br1 as a mounting portion is formed facing the developing roller 41Bk in the housing 34, the seal material 72 is adhered to the bracket Br1, and the tip of the seal material 72 contacts the developing roller 41Bk. Touched.

  The spiral 71 is provided with a gear (not shown) at one end, in the present embodiment, at the right end, and the gear and a gear (not shown) disposed at the right end of the photosensitive drum 52Bk are engaged with each other. Note that the left end of the spiral 71 exists at the left end of the image forming unit 22Bk.

  In FIG. 15, reference numeral 73 denotes a toothed waste toner conveyance belt as a waste developer conveyance member, and the waste toner conveyance belt 73 is a left side as a side case disposed at both ends of the photosensitive drum 52Bk. It is housed in a groove 101 formed in the side cover 81 and is driven in the direction of the arrow in the groove 101 by driving a conveyance motor as a drive unit (not shown).

  For this purpose, a gear g1 is disposed in the left side cover 81, and the gear g1 and the waste toner conveying belt 73 are engaged with each other. The gear g1 is interlocked with the gear disposed on the photosensitive drum 52Bk via a gear (not shown) disposed on the sponge roller 43Bk, and is accompanied by the rotation of the sponge roller 43Bk and the photosensitive drum 52Bk. Rotates and causes the waste toner conveying belt 73 to travel.

  Further, the left side cover 81 faces the groove 101 at a predetermined position, and waste toner carry-in ports 102 and 103 as first and second waste developer inlets, and waste developer outlets. A waste toner carry-out port 104 is formed. Then, the waste toner conveyed by rotating the spiral 71 enters the groove 101 from the waste toner carry-in port 102, is carried by the waste toner carry belt 73, and is disposed from the waste toner carry-out port 104 through the waste toner reservoir 48 ( 3). Further, the toner 16 scraped from the photosensitive drum 52Bk by the cleaning blade 44 (FIG. 3) is transported and recovered as a waste toner as a transport member and by a spiral (not shown) as a recovery member. The toner enters the groove 101 from the carry-in port 103, is conveyed by the waste toner conveyance belt 73, and is discharged from the waste toner carry-out port 104 to the waste toner reservoir 48.

  The spiral 71 is made of ABS resin containing glass fiber. In this case, the glass fiber constitutes a filler, and the ABS constitutes a base resin. Moreover, the sealing material 72 is formed of resin, in this embodiment, thermoplastic urethane.

  Thus, since the spiral 71 and the photosensitive drum 52Bk are interlocked, the spiral 71 rotates with the rotation of the photosensitive drum 52Bk, and the toner 16 scraped off by the sponge member 47 becomes waste toner. It is sent to the left side cover 81, scraped off by the cleaning blade 44 at the left side cover 81, and sent to the waste toner reservoir 48 together with the conveyed waste toner and collected.

  Therefore, the toner 16 scraped off by the sponge member 47 is not mixed with the new toner 16, and the waste toner can be reliably collected.

  Next, a third embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st, 2nd embodiment, the same code | symbol is provided and the effect of the embodiment is used about the effect of the invention by having the same structure.

  FIG. 17 is a cross-sectional view of a sponge member according to the third embodiment of the present invention.

  In this case, the cross section in the lateral direction of the core material 46 has a trapezoidal shape, and the upper surface that contacts the sponge material 45 has a surface area smaller than that of the first embodiment.

  Accordingly, since the repulsive force per unit area with respect to the developing roller 41Bk is increased, the toner 16 on the developing roller 41Bk can be easily scraped off.

  By the way, in a printer capable of performing printing at high speed, the rotation speed of the developing roller 41Bk is increased, so that the toner 16 easily slips through the sponge material 45, and scraping becomes difficult. Therefore, when the core material 46 having a shape with high scraping property as in the present embodiment is used, scraping can be performed satisfactorily even when printing is performed at high speed.

  The sponge member 47 is formed by adhering the sponge material 45 to the surface of the core material 46, and the sponge member 47 itself is also fixed to the housing 34 by screws bt (FIG. 4). Therefore, the core material 46 can be easily replaced. Further, since the image forming unit 22Bk and the sponge member 47 are independent, for example, the same image forming unit 22Bk can be reused only by replacing the new sponge member 47. Further, by replacing the sponge member 47 suitable for low-speed printing with the sponge member 47 suitable for high-speed printing, printing is performed with two types of printers having different printing speeds using the same image forming unit 22Bk. be able to.

  Next, a fourth embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st-3rd embodiment, the same code | symbol is provided and the effect of the same embodiment is used about the effect of the invention by having the same structure.

  FIG. 18 is a cross-sectional view of a sponge member according to the fourth embodiment of the present invention.

  In this case, the cross section in the lateral direction of the core member 46 has a rectangular shape, and the bottom surface and the surface area of the upper surface in contact with the sponge material 45 are equal.

  As described above, since the contact area between the developing roller 41Bk and the sponge material 45 is increased, the repulsive force of the sponge material 45 on the developing roller 41Bk can be reduced. Therefore, for example, the developing roller 41Bk is rotated at the time of printing by being applied to a printer that performs printing at a low speed, such as a printer that performs monochrome printing, in which the toner 16 does not easily pass through the sponge material 45. The torque can be reduced.

  Next, a fifth embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st-4th embodiment, the same code | symbol is provided and the effect of the embodiment is used about the effect of the invention by having the same structure.

  FIG. 19 is a cross-sectional view showing the main part of an image forming unit according to the fifth embodiment of the present invention.

  In this case, a sheet-like seal is formed on the inner peripheral surface of the housing 34 so as to face a portion downstream of the sponge member 47 in the rotation direction of the developing roller 41Bk and upstream of the contact portion with the sponge roller 43Bk. A film 85 as a member is provided, and the leading end of the film 85 is brought into contact with the developing roller 41Bk.

  In the present embodiment, the toner 85 can be prevented from leaking by the film 85 and the sponge member 47.

  In each of the above embodiments, the printer as the image forming apparatus has been described. However, the present invention can be applied to a copying machine, a facsimile machine, a multifunction machine, and the like.

  The present invention is not limited to the above embodiments, and various modifications can be made based on the gist of the present invention, and they are not excluded from the scope of the present invention.

FIG. 2 is a cross-sectional view showing a main part of the image forming unit in the first embodiment of the present invention. 1 is a schematic diagram of a printer according to a first embodiment of the present invention. FIG. 2 is a conceptual diagram of an image forming unit according to the first embodiment of the present invention. It is a perspective view which shows the attachment state of the sponge member in the 1st Embodiment of this invention. It is a 1st figure which shows the relationship between the developing roller and sponge member in the 1st Embodiment of this invention. It is a 2nd figure which shows the relationship between the developing roller and sponge member in the 1st Embodiment of this invention. It is a 3rd figure which shows the relationship between the developing roller and sponge member in the 1st Embodiment of this invention. It is a figure which shows the state of the sponge member at the time of the non-printing in the 1st Embodiment of this invention. It is a figure which shows the state of the sponge member at the time of the printing in the 1st Embodiment of this invention. It is a figure explaining the force added to the developing roller in the 1st Embodiment of this invention. It is a 1st figure explaining the effect | action of the sponge member in the 1st Embodiment of this invention. It is a 2nd figure explaining the effect | action of the sponge member in the 1st Embodiment of this invention. It is a figure explaining the method of the impact test in the 1st Embodiment of this invention. It is sectional drawing which shows the principal part of the image forming unit in the 2nd Embodiment of this invention. It is a figure which shows the structure in the side frame of the image forming unit in the 2nd Embodiment of this invention. It is a front view of the spiral in the 2nd Embodiment of this invention. It is sectional drawing of the sponge member in the 3rd Embodiment of this invention. It is sectional drawing of the sponge member in the 4th Embodiment of this invention. It is sectional drawing which shows the principal part of the image forming unit in the 5th Embodiment of this invention.

Explanation of symbols

16 Toner 22Bk, 22Y, 22M, 22C Image forming unit 34 Housing 41Bk Developing roller 47 Sponge members 52Bk, 52Y, 52M, 52C Photosensitive drum 85 Film

Claims (7)

(A) a housing;
(B) a developer carrier that is rotatably disposed in the housing, carries a developer, and develops a latent image formed on the image carrier;
(C) a seal member that is disposed along the axial direction of the developer carrier and prevents the developer from leaking between the developer carrier and the housing;
(D) the seal member includes a sponge material disposed in contact with the developer carrier, and a surface area of a bottom surface that is greater than a surface area of an upper surface contacting the sponge material; An image forming unit comprising a core material having a trapezoidal shape larger than a surface area and supporting the sponge material.   The image forming unit according to claim 1, wherein the sponge material is attached to a surface of a core material. (A) a transport member that transports the developer scraped off by the sponge material along the axial direction of the developer carrier, and supplies the developer to a waste developer inlet formed in the side housing;
(B) Disposal that is movably disposed in the side housing, transports the developer supplied to the waste developer inlet to the waste developer outlet, and discharges the developer from the waste developer outlet to the waste developer container. The image forming unit according to claim 1, further comprising a developer conveying member. When the radius of the developer carrier is r, the thickness of the sponge material when not in contact with the developer carrier is L1, and the developer carrier when the developer carrier and the sponge material are in contact with each other When the distance between the center axis of the body and the top surface of the core is L2,
(R + L1-L2) /L1=0.06
The image forming unit according to claim 1.   The image forming unit according to claim 1, wherein the seal member is disposed independently of the housing and is fixed to the housing with screws.   The image forming unit according to claim 1, wherein the sponge material has an Asker hardness of 30 or more and 55 or less.   An image forming apparatus on which the image forming unit according to claim 1 is mounted.

Images