JP4086736B2 - Developing device and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device used for developing and visualizing an electrostatic latent image formed on the surface of an image carrier in an image forming apparatus using an electrophotographic system, and more particularly to an image carrier and a developer carrier. In particular, the present invention relates to a developing device and an image forming apparatus that perform a non-contact development by an AC electric field with a predetermined interval therebetween.

  Conventionally, as an image forming apparatus such as a laser beam printer or a copying machine, an image forming apparatus using an electrophotographic method as shown in FIG. 19 has been proposed. These basic operations will be described below.

  In an image forming process, an electrophotographic photosensitive member (hereinafter referred to as a “photosensitive drum”) 11 that is a normal drum-like, ie, rotating body, as an image carrier is first uniformly formed by a primary charger 12 in a charging process. Is charged. Next, the surface of the photosensitive drum 11 is irradiated with light from the exposure device 13 in accordance with the image information input from the external device in the exposure step, which is a latent image forming step, to form a latent image. Next, in the developing process, the electrostatic latent image on the surface of the photosensitive drum 11 is developed in the developing device 60 with a developer (hereinafter referred to as “toner”) having a triboelectric charge polarity that is the same as the voltage applied to the primary charger 12. .) A visible image, that is, a developer image (toner image) is formed by T. This toner image is transferred to the transfer material Q by the transfer charger 14 in the transfer process. The transfer material Q is separated from the photosensitive drum 11 and subsequently conveyed to the fixing device 16 in a fixing process, and becomes a permanent image after fixing by the fixing device 16. Further, the developer T on the surface of the photosensitive drum 11 remaining without being transferred by the transfer charger 14 is removed by the cleaning device 15, and the photosensitive drum 11 is subjected to the next image forming process (image forming process).

  The developing device 60 that mainly performs the developing step in the image forming process performed by the image forming apparatus will be described.

  The toner T contained in the developing device 60 and used as a developer is a negatively chargeable non-magnetic one-component toner that is negatively charged and contains a pigment of any one of yellow, magenta, cyan, and black.

  The toner T is accommodated in a developing container 60a serving as a developing device main body cover, and is agitated by stirring members 64 and 65 installed in the developing container 60 to be kept uniform. As for the stirring member 64, a toner first stirring member 64 and a toner second stirring member 65 which are formed of plates or screws processed into various shapes are provided in parallel to the axial direction of the photosensitive drum 11, and in the drawing. Rotating in the direction of the arrow, the toner T in the toner container (developing container) 60a is conveyed to the developing roller 61 which is a rotating member as a developer carrying member. The number of the agitating members is not limited to two, and the number of agitating members is not limited as long as the toner can be conveyed from the inside of the developing container 60a to the vicinity of the developing roller 61 according to various developing device configurations.

  The developing container 60a has a developing container partition plate 66 between the developing roller 61 and the stirring member 64 installed on the developing roller 61 side of the two stirring members. That is, the developing container 60a has a developing container 60a. The developing unit 60b for supplying the toner T to the roller 61 and the stirring unit 60c for storing and stirring the toner T are partitioned. The height of the partition plate 66 is optimized so that a constant amount of toner T is always supplied to the surface of the developer supply and stripping roller 62 in the vicinity of the developing roller 61 in the developing portion where the developing roller 61 is provided.

  In the non-magnetic one-component development method, toner cannot be supplied by magnetic force. Therefore, in the developing unit 60b, the developer supply stripping roller 62 made of urethane sponge contacts the developing roller 61 as described above. Has been. The developer supply stripping roller 62 rotates in the counter direction at the nip portion with the developing roller 61 so that the toner T is supplied to the surface of the developing roller 61 and at the same time is not developed even when passing through the position facing the photosensitive drum 11. The toner on the surface of the developing roller 61 is removed.

  The developing roller 61 is in contact with a regulating blade 63 as a developer amount regulating member, regulates toner on the surface of the developing roller 61, forms a thin toner layer, and conveys it to the developing area (drum facing position) 70. This defines the amount of toner to be used. The amount of toner conveyed to the development area 70 is determined by the contact pressure and contact length of the regulating blade 63 that contacts the surface of the development roller 61.

  The regulating blade 63 is adhered or welded to the surface of a thin metal plate made of phosphor bronze, stainless steel or the like having a thickness of several hundreds of μm, and the regulation blade 63 is uniformly abutted against the developing roller 61 by the elasticity of the metallic thin plate. It is a blade. At this time, the contact condition of the regulating blade 63 is determined by the material, thickness, penetration amount, and set angle of the thin metal plate.

  The developing roller 61 is opposed to the surface of the photosensitive drum 11 with a predetermined distance (hereinafter referred to as “SD gap”) in the developing region 70, and an AC electric field that is an oscillating electric field when a bias is applied. Is forming.

  In the above configuration, the toner T adhered to the surface of the developing roller 61 with a desired charge amount and a desired layer thickness and conveyed to the developing region 70 is transferred to the surface of the developing roller 61 by the AC electric field. A reciprocating motion is performed between the developing roller 61 and the photosensitive drum 11 to visualize the electrostatic latent image formed on the surface of the photosensitive drum 11.

  However, in this way, in the developing device 60 that performs development using an alternating electric field, an image defect called “pumping” occurs.

  Hereinafter, the “rushing phenomenon” will be described with reference to FIG. FIG. 20 is a model diagram in which the facing portion 70 between the photosensitive drum 11 and the developing roller 61 is observed from the side with respect to the rotation direction.

  The close-up is a phenomenon in which a large amount of toner collects in the image rear end H that is the upstream portion of the developing roller 61 in the rotation direction in the developing region 70.

  When such a toner image is formed, an image defect in which a dark portion is seen in the image is caused.

  When an AC bias (AC bias) is applied between the photosensitive drum 11 and the developing roller 61 as shown in FIG. 20, a barrel-shaped electric field D is generated. Then, the toner T1 adhering to the surface of the developing roller 61 reciprocates between the photosensitive drum 11 and the developing roller 61 along the electric force line D formed by the electric field D. Then, the photosensitive drum 11 and the developing roller 61 move outward from the closest point S. That is, when an AC bias is applied, the toner T1 in the development area 70 always has a velocity component that moves outward from the development area 70. The toner T1 accumulates on the upstream side H of the developing roller 61 in the rotation direction of the developing roller 61 in accordance with the outward pushing by the electric force line D and the rotating direction of the photosensitive drum 11.

  Here, a case where the photosensitive drum 11 and the developing roller 61 are rotated in the direction of the arrow in the drawing to form a latent image, that is, a case where actual development is being performed will be described. In FIG. 20, a portion A where the photosensitive drum 11 charging potential Vd is −100 V is a latent image portion, and is a region where a toner image is formed. A portion B where Vd is −500 V is a reference potential of the photosensitive drum 11 by the primary charger 12 and is a region where a toner image is not formed. When the latent image portion A reaches the developing region 70, the toner on the surface of the developing roller 61 adheres to the latent image portion A. However, as described above, the flying toner T1 moves to the outside of the developing region 70. Since there is a component, the latent image portion A moves to the upstream side in the rotation direction of the developing roller 61.

  An electric field from −500 V to −100 V is generated at the boundary between the portion A where Vd = −100 V and the portion B where Vd = −500 V. As a result, the negative toner T1 that has moved to the upstream side in the rotation direction of the developing roller 61 of the latent image portion A stays at this boundary. For this reason, the amount of toner upstream of the latent image portion A and the central portion S in the rotation direction of the developing roller 61 increases, and a close-up H is formed in these portions.

As a method for reducing the toner staying portion, that is, the swept image due to the rushing H, a proposal has been made in Patent Document 1 to insert a plate-like member having an electrode in the development region 70 to reduce the lashing. . However, when the image forming operation is repeatedly performed and the developing device 60 is near the end of its life, an image and toner scattering are generated from the edge of the image, that is, from both ends of the paper.
JP-A-8-22185

  SUMMARY OF THE INVENTION An object of the present invention is to provide a developer carrying body and an image carrier over a long period of time with a simple configuration in a developing device that performs a developing operation by moving the developer from the developer carrier to the image carrier by an alternating electric field. It is an object to provide a developing device and an image forming apparatus that suppress the sweeping and scattering toner adhering to occur in a developing area that is a portion opposite to the surface, and form a good image.

The above object is achieved by the developing device and the image forming apparatus according to the present invention. In summary, the first aspect of the present invention includes a developer container that contains a developer, and a developer carrier that is a rotating body that carries and transports the developer, and an electrostatic latent image is formed thereon. The developer carrier is opposed to an image carrier, which is a rotating body that bears an electrostatic latent image, and an oscillating electric field is formed in a developing region located at the facing portion, and the developer carrier is borne by the oscillating electric field. It carries at the surface by the developer conveyed to the developing area, the developing device for developing the electrostatic latent image,
In the image guarantee area of the image carrier in a direction parallel to the axial direction of the developer carrier, a plate-like member having a tip portion entering the development area from the upstream in the rotation direction of the image carrier, the development member agent parallel width in the axial direction of the bearing member, have a broader flight developer control member than before Kiga image assurance area in the same direction, the flight in the longitudinal direction of the end portion of the flying developer control member The developing device is characterized in that a leading end portion of the developer control member is provided so as to protrude downstream from the leading end portion of the flying developer control member in the image guarantee area in the rotation direction of the image carrier .

  According to an embodiment of the first aspect of the present invention, the flying developer control member enters from the upstream side in the rotation direction of the developer carrying member with one end arranged in the developing region, and the flying developer control member The intrusion start portion of the developer control member is an angle in the reverse rotation direction of the developer carrier, and the position connecting the rotation centers of the developer carrier and the image carrier is 0 °, and the direction is 30 °. The distance from the edge of the flying developer control member existing in the development region in a direction along the flying developer control member from a position intersecting with the extension portion extending the radius of the developer carrier. In a long position.

According to a first alternative embodiment of the present invention, the longitudinal end portion of the flying developer control member, the or opposed to the entire region of the developer carrying member rotation direction of the developing region, or the A longitudinal end portion of the flying developer control member has a shape refracted toward the developer carrier, or a longitudinal end portion of the flying developer control member is the image carrier and the developer. It is preferable to be in contact with or close to a member that keeps the distance from the carrier constant.

  According to a second aspect of the present invention, there is provided an image forming apparatus comprising: an image carrier on which an electrostatic latent image is formed on a surface; and the developing device according to the first aspect of the present invention that develops the electrostatic latent image. To do.

In the developing device and the image forming apparatus of the present invention , an electrostatic latent image is formed, and a developer carrying member is opposed to an image carrier that is a rotating member that carries the electrostatic latent image, and a developing region located in a facing portion is provided. Te, the oscillating electric field to form an oscillating electric field, in the developer conveyed by supporting a developing region at the surface of the developer carrying member in the developing device for developing an electrostatic latent image, in the axial direction of the developer carrying member In the image guarantee area of the image carrier in the parallel direction, it is a plate-like member whose leading end has entered the development area from the upstream in the rotation direction of the image carrier , and has a width in a direction parallel to the axial direction of the developer carrier. , have a broader flight developer control member than images guarantee area that put in the same direction, the tip of the flight developer control member in the longitudinal direction of the end of the flight the developer control member, flying developing the image assurance area The rotation direction of the image carrier is lower than the tip of the agent control member Since is provided to protrude, to the developing device life, sweeping of the developer caused in the developing region, to prevent the developer scattering from the end portion, and outputs a stable image.

  Hereinafter, the developing device and the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

Example 1
A developing device in this embodiment is shown in FIG. A developing apparatus 100 shown in FIG. 1 is one in which the present invention is applied to a developing device of a non-magnetic one-component non-contact developing system. Hereinafter, the developing device 100 will be described in detail.

  The developing device 100 of this embodiment is provided at the position of the developing device 60 of the image forming apparatus having the configuration shown in FIG. 19 described in the conventional example, and an image is formed in the developing process of the image forming process described in the conventional example. It is assumed that the electrostatic latent image formed on the surface of the photosensitive drum 1 which is a carrier is developed. In FIG. 1, a developing device 100 is provided in parallel with a peripheral surface facing a photosensitive drum 1 which is a rotating body as an image carrier, and a developer container 100a for containing a developer, and a developer carrier. A developer roller 2 as a rotating member, a developer supply stripping roller 3 as a developer supply member, a toner regulating member 4, a flying developer control member (control member) 5 as a plate member, and a plate-like member And a toner agitating member 6, and the developer container 100 a contains toner T, which is an insulating non-magnetic one-component developer.

  As the photosensitive drum 1 facing the developing device 100, a member constituted by coating a photosensitive material such as OPC on the surface of an aluminum base tube having an outer diameter of 30 mm was used.

  Then, each member included in the developing device 100 will be described.

  As the developing roller 2 as a developer carrier, a member obtained by spray-coating a phenol resin solution in which carbon and graphite are dispersed on the surface of an aluminum base tube having an outer diameter of 16 mm was used. As shown in FIG. 3, rollers 21 are installed at both ends in the axial direction of the developing roller 2 and abut against the surface of the photosensitive drum 1 to maintain a constant SD gap between the photosensitive drum 1 and the developing roller 2. Here, the SD gap was set to 300 μm.

  As the developer supply peeling roller 3, a member in which a 4.5 mm thick urethane foam was formed on the outer periphery of a metal core having an outer diameter of 5 mm was used.

  As the toner regulating member 4, a phosphor bronze plate having a thickness of 0.1 mm was used.

  Here, the operation of the developing device 100 will be described.

  The toner T is a negatively chargeable non-magnetic one-component toner that is negatively charged and contains a pigment of any one of yellow, magenta, cyan, and black.

  In the developing device 100 of this embodiment, one agitating member 6 is provided in the direction of one axis of the photosensitive drum. A toner stirring member 6, which is the stirring member, is arranged so as to be able to rotate in the direction of the arrow in the drawing, and the toner T in the toner storage portion is conveyed to the developing roller 2. Also in this embodiment, like the conventional example, the developing container 100a is divided by the developing container partition plate 7 into the developing unit 100b in which the developing roller 2 is installed and 100c in which the stirring member 6 is installed. The height of the partition plate 7 is optimized so that an amount of toner T is supplied to the surface of the developer supply stripping roller 3 near the developing roller 2.

  The developer supply stripping roller 3 is in contact with the developing roller 2 and rotates in the counter direction at the nip portion to supply the toner T to the surface of the developing roller 2 and at the same time pass through the position facing the photosensitive drum 1. Also, the toner on the surface of the developing roller 2 that was not developed is stripped off.

  The developing roller 2 exposes a part of the peripheral surface from the developing container 100a toward the peripheral surface of the photosensitive drum 1, and the exposed portion is exposed to the opening of the developing container 100a upstream of the developing roller 2 in the rotation direction. The developing roller 2 is in contact with a regulating blade 4 as a toner amount regulating member, regulates the toner on the surface of the developing roller 2 to form a thin toner layer, and the amount of toner conveyed to the developing area 70 At the same time, the toner is charged.

  In the above configuration, the toner T that adheres to the surface of the developing roller 2 with a desired charge amount and a desired layer thickness and is conveyed to the developing region 70 is developed by the developing bias applied to the developing roller 2. The toner T adhering to the surface reciprocates between the developing roller 2 and the photosensitive drum 1 to visualize the electrostatic latent image formed on the surface of the photosensitive drum 1.

  Here, each setting condition in the developing device 100 in the present embodiment will be described.

  The photosensitive drum 1 rotates in the direction of the arrow in the figure, and the developing roller 2 rotates in the direction of the arrow in the figure. That is, in this embodiment, the rotation directions of the photosensitive drum 1 and the developing roller 2 are the same direction, that is, the forward direction, at the facing portion 70. This can be the counter direction depending on the image forming conditions.

  As the developing bias, an oscillating voltage obtained by superimposing a DC bias of −260 V on an AC bias having an AC amplitude of 2 kV and an AC frequency of 3 kHz was used. By this oscillating voltage, an alternating electric field (oscillating electric field) is formed between the developing roller 2 and the photosensitive drum 1 (dark portion potential and light portion potential of the photosensitive drum).

  Further, in order to make the toner T on the surface layer of the developing roller 2 a uniform thin layer, the toner regulating member 4 is provided on the developing roller 2 at a linear pressure of 30 g / cm in the counter direction with respect to the rotating direction of the developing roller 2. Abut.

  In such a developing device 100, the feature of this embodiment is that a flying developer control member (control member) 5 which is a plate-like member is inserted into the developing region 70 in order to prevent toner scattering and ejection in the developing region 70. It was established. The control member 5 of Example 1 is demonstrated using figures. FIG. 2 is an enlarged view of the vicinity of the developing region 70 in the developing device 100 according to the first embodiment, and is a diagram viewed from the side surface in the rotation direction of the developing roller 2 and the photosensitive drum 1.

  The flying developer control member 5 has one end side 5 a of the control member 5 in the developing region 70 from the upstream side in the rotation direction of the developing roller 2 in the developing region 70, which is a facing portion between the photosensitive drum 1 and the developing roller 2. Arrange them so that they invade.

  For example, here, the control member 5 is arranged so that the one end side 5 a of the control member 5 exists at the approximate center S of the development region 70. In other words, the control member 5 enters the developing region 70, that is, the facing portion between the photosensitive drum 1 and the developing device 2 from the upstream side in the rotation direction of the developing roller 2 so that the one end side 5 a that is the foremost end is in the developing region 70. It is a plate-shaped member. In other words, the control member 5 is a plate-like member that protrudes upstream in the rotation direction of the developing roller 2 with the one end 5 a interposed between the photosensitive drum 1 and the developing roller 2. In this embodiment, the other end side 5b symmetrical to the one end side 5a existing in the developing region 70 of the control member 5 is fixed to the developing container 100a of the developing device 100 as shown in FIG. However, if the one end portion 5a is in the developing region 70, the other end 5b serving as a fixing portion may be fixed to a member other than the developing device 100 of the image forming apparatus.

  FIG. 3 is an arrangement configuration diagram of the control member 5 viewed from the photosensitive drum 1 side in the developing device 100 of the first embodiment. SD rollers 21 are provided at both ends of the developing roller 2 in the axial direction, and an SD gap of 300 μm is maintained. The area (width) of the control member 5 in the axial direction of the developing roller 2 is arranged wider than the image guarantee area in which an image is formed in a direction parallel to the axial direction of the developing roller 2.

  The distance between the edge 5a existing in the developing region 70 of the control member 5 and the developing roller 2 and the photosensitive drum 1 is not particularly limited. However, the distance between the photosensitive drum 1 and the developing roller 2 or near the control member 5 is not limited. In order to maintain the position of the one end side 5a, it is preferable to press and contact the surface of the photosensitive drum 1.

  Here, the developing region 70 where the control member 5 is installed is defined and a measuring method thereof is shown.

  In the developing device 100, AC on which the toner on the surface of the developing roller 2 can sufficiently fly in a state where the charged toner T is attached to the surface of the developing roller 2 and the photosensitive drum 1 and the developing roller 2 are stopped. Apply a bias. At that time, on the surface of the developing roller 2 near the surface of the photosensitive drum 1, the toner T does not exist, or a region where the toner layer is less than the surroundings and a region where the toner layer is thick are generated at both ends of the region.

  A model of this situation is shown in FIG. In FIG. 4, when an AC bias is applied between the photosensitive drum 1 and the developing roller 2, a curved electric field is formed between the photosensitive drum 1 and the developing roller 2 as illustrated. The toner near the center 70 of the facing portion 70 moves along the curved electric field in the direction of the arrow in the drawing, that is, toward the outside of the center S of the facing portion 70. Further, as the distance from the center S of the facing portion 70 is increased, the SD gap is increased, so that the influence of the AC bias is reduced and the movement of the toner is also reduced. Outside of a and d in the figure, the toner on the developing roller is not affected by the AC bias. As a result, a portion that is shown symmetrically with respect to the opposite center 70 center S, which is shown as between ab and cd, becomes a thick region of the toner layer T. The thick regions ab and cd The area between bc including the central part S of the development area 70 between the areas where there is no toner T or the toner layer T is smaller than the surrounding area.

  In FIG. 4, a development area 70 is defined between a and d where the thick area and the small area of the toner layer are combined. The development area 70 where the tip 5a of the control member 5 is present is an area between the above-mentioned ad. The width of the development area 70 is the diameter of the photosensitive drum 1 and the development roller 2, the SD gap, the environment such as temperature, humidity, and atmospheric pressure, the development bias, the development bias application time, the charge amount of the toner T, and the toner on the surface of the development roller 2. It varies depending on the amount of adhesion.

In the present embodiment, according to experiments by the present inventors, the diameter of the photosensitive drum 1 is 30 mm, the diameter of the developing roller 2 is 16 mm, the SD gap is 300 μm, the average charge amount of the toner T on the surface of the developing roller 2 is 40 μC / g, The toner adhesion amount per surface area on the developing roller 2 is 0.5 mg / cm ² , and the frequency is 2500 Hz between the photosensitive drum 1 and the developing roller 2 under the environment of 1 atm and 20 ° C. and 60% humidity. When an AC bias having an AC amplitude of 2000 V was applied for 1 second, the developing area 70 was 4 mm in the circumferential direction of the developing roller 2.

  In this way, by providing the control member 5 so that the tip 5a exists in the developing region 70 over a region wider than the image guarantee region of the developing roller 2 in the direction intersecting the circumferential direction, that is, in the axial direction, The sweeping portion is restricted by the control member 5 and does not adhere to the surface of the photosensitive drum 1, and it is possible to form a good image over a long period of time. Further, this effect is ensured by being provided upstream in the rotation direction of the developing roller 2.

Example 2
In this embodiment, only the width of the flying developer control member 5 in the direction of the developing roller 2 axis is changed in the developing device 100 having the same configuration and setting conditions as in the first embodiment.

  FIG. 5 is an arrangement configuration diagram of the control member 5 viewed from the photosensitive drum 1 side in the present embodiment. About the structure and operation | movement of the image development apparatus 100, about the thing similar to Example 1, the description is abbreviate | omitted.

  In the present embodiment, the length of the control member 5 in the axial direction of the developing roller 2 is longer than the width of the toner coat layer in the axial direction of the surface of the developing roller 2.

  Depending on the image forming conditions, development may be performed in an area larger than the image guarantee area. Further, a toner layer may be provided on the developing roller 2 wider than the developing area 70. In such a case, if the control member 5 is provided wider than the toner coat layer of the developing roller 2, the generation of the sweeping toner can be prevented more reliably.

  Here, the effect of Example 1 and Example 2 is demonstrated using the comparative example 1 below.

Comparative Example 1
FIG. 12 is an arrangement configuration diagram of the control member 5 as viewed from the photosensitive drum 1 side in the first comparative example. In this comparative example, only the width of the control member 5 in the axial direction of the developing roller 2 is changed in the developing device 100 having the same configuration and setting conditions as in the first embodiment. About the structure and operation | movement of the image development apparatus 100, about the thing similar to Example 1, the description is abbreviate | omitted.

  In Comparative Example 1, as shown in FIG. 12, the width of the control member 5 in the axial direction of the photosensitive drum 1 and the developing roller 2 is shorter than the image guarantee area.

  Table 1 shows a comparison between the first and second image defects in the first and second embodiments and this comparative example.

  As shown in Table 1, when the flying developer control member 5 has a narrower width in the axial direction of the photosensitive drum 1 and the developing roller 2 than in the image guarantee area as in this comparative example, the edge of the image is gathered. The image cannot be prevented, and the toner swept up at the facing portion between the developing roller 2 and the photosensitive drum 1 is scattered, so that the scattered toner drops onto the surface of the developing roller 2 or the scattered toner of the developing device 100. Dirt is also produced.

  Therefore, as in the first exemplary embodiment, the control member 5 is made longer than the image guarantee area, thereby preventing the image that reaches the edge of the image, the toner dropping, and the toner contamination, and the developing device 100. Can be maintained at a problem-free level until near the end of its service life.

  Further, as in the second embodiment, by making the length of the control member 5 longer than the length of the toner coat layer on the surface of the developing roller 2, it is possible to surely prevent the edge-appearing image and toner from dropping off. It becomes possible.

Example 3
In this embodiment, only the arrangement of the flying developer control member 5 is changed in the developing device 100 having the same configuration and setting conditions as in the first embodiment.

  FIG. 6 is an enlarged view of the vicinity of the developing region 70 as viewed from the side with respect to the rotation direction of the developing roller 2 and the photosensitive drum 1 in this embodiment. FIG. 7 is an arrangement configuration diagram of the control member 5 viewed from the photosensitive drum 1 side in this embodiment. About the structure and operation | movement of the image development apparatus 100, about the thing similar to Example 1, the description is abbreviate | omitted.

  In this embodiment, the control member 5 which is a plate-like member has an end 5a existing in the developing region 70 as a leading end, and a length from the end 5a toward the upstream side in the rotation direction of the developing roller 2 is defined as L. The end length L is determined as follows.

  Here, in the control member 5 that is a plate-like member, the position of the end side 5 b that is symmetrical to the end side 5 a is set to the end side of the region where the plate-like member that constitutes the control member 5 exists as the control member 5. And For example, in this embodiment, the plate-like member constituting the control member 5 has an end portion facing the end side 5a attached to another member, here, the developing container 100a, and the developing container 100a and the control member The width between the portions 5 is narrower than that of the control member 5. The narrowed portion is used as a mounting portion of the developing container 100a, and the developing container 100a mounting portion is ignored, and the boundary between the end of the portion existing as the control member 5, that is, the mounting portion with the developing container 100a. Is considered as the edge 5b. The distance between the end side 5a and the end side 5b, that is, the length in the direction intersecting the end side 5a of the control member 5 that is a plate-like member is defined as the end portion length L.

  When the control member 5 is considered to be a plate-like member that has entered from the upstream side in the rotation direction of the developing roller 2, the intrusion tip is the end side 5a, so the end side 5b can be said to be an entry start portion. The end length L direction is a direction along the control member 5 and can be said to be an entry direction into the development region 70.

  As shown in FIGS. 6 and 7, this end portion length L connects the rotation shafts of the developing roller 2 and the photosensitive drum 1 from the portion facing the front end portion 5 a of the control member 5 on the circumferential surface of the developing roller 2. The length is required to cover the toner coat layer on the surface of the developing roller 2 over an area of 30 ° or more in the reverse rotation direction of the developing roller 2 with respect to the center line segment P1.

  That is, from the center of the developing roller 2, the center line segment P1 is set to 0 ° on the circumferential surface of the developing roller 2, and the developing roller 2 radius extension portion extended from there in the direction of 30 ° in the reverse rotation direction of the developing roller 2. Is set to P2, the control member is located outside the position 5c where the extension P2 and the control member 5 intersect, that is, in the direction along the control member 5, from the position 5c where the development roller 2 radius extension P2 intersects. It is necessary that the intrusion start portion 5b exists at a position where the end portion length L, which is the distance from the end side 5a, is long.

  By determining the end length L as described above, it is possible to prevent the sweeping toner from moving to the photosensitive drum 1 over a long period of time.

  The effect of the present embodiment will be described below using Comparative Example 2.

Comparative Example 2
FIG. 13 is an end layout diagram of the control member 5 as viewed from the photosensitive drum 1 side in the third comparative example. FIG. 14 is an enlarged explanatory view in the vicinity of the development region 70 in this comparative example.

  In this comparative example, only the arrangement of the flying developer control member 5 is changed in the developing device 100 having the same configuration and setting conditions as in the first embodiment. About the structure and operation | movement of the image development apparatus 100, about the thing similar to Example 1, the description is abbreviate | omitted.

  As a feature of this comparative example, as shown in FIGS. 13 and 14, unlike the third embodiment, the end length L is a portion where the front end portion 5 a of the control member 5 faces the developing roller 2 and the photosensitive drum 1. From the center line P1 connecting the rotation axes of the developing roller 2 and the photosensitive drum 1, the length that covers the toner coat layer on the surface of the developing roller 2 over a region of 30 ° or more in the reverse rotation direction of the developing roller 2 Arranged not to.

  Here, the concern in the non-contact developing type developing apparatus in which the member 5 is inserted into the developing region 70 will be described.

  FIG. 15 is a model diagram showing toner movement on the upstream side of the development area 70. The reference numerals are the same as those in the first embodiment, and the description thereof is omitted.

  When a developing bias is applied between the photosensitive drum 1 and the developing roller 2 that are rotationally driven in the forward direction in the direction of the arrow in the drawing, the toner is in the direction of the arrow in the drawing, that is, the developing roller 2 and the photosensitive roller. While moving zigzag in the direction along the surface of the drum 1, it moves in the direction from the developing roller 2 to the photosensitive drum 1.

  That is, the toner near the center of the SD gap is affected by the barrel-shaped electric field and moves outward from the center S of the development area 70. On the other hand, the toner in the vicinity of the surfaces of the photosensitive drum 1 and the developing roller 2 is moved in the rotation direction under the influence of the airflow generated by the rotation of the photosensitive drum 1 and the developing roller 2.

  Due to the movement of the toner T, the toner existing on the upstream side of the developing region 70 moves while swirling as shown in the drawing. Here, when the control member 5 exists, the space in which the toner T moves is reduced by the presence of the control member 5 as shown in FIG. 16 which models the movement of the toner T in that case. The movement of the toner T flying between the developing roller 2 and the control member 5 becomes more intense.

  Due to this phenomenon, the toner T flies also on the upstream side in the rotation direction of the developing roller 2 and outside the developing area 70 at the end of the developing roller 2. Then, the flying toner accumulates on the surface of the control member 5 on the photosensitive drum 1 side. The result is shown in FIG. 17 which is a model diagram. The scattered toner T adheres to the surface of the control member 5 on the side of the photosensitive drum 1, particularly at the end in a direction parallel to the developing roller biaxial direction. When such toner increases due to repeated image forming operations, the following problems occur.

1: Generation of a close-up image at the edge of the image This is because toner accumulated on the side surface of the photosensitive drum 1 of the flying developer control member 5 reciprocates between the photosensitive drum 1 and the control member 5 due to an oscillating electric field of the developing bias. This is an image defect that forms a close-up image.

2: Unevenness of the contact image This is because the control member 5 is deformed into a crown shape or the like by the toner accumulated on the side surface of the photosensitive drum 1 of the control member 5, and the contact is made between the central portion and the end portion in the longitudinal direction. This is an image defect that causes unevenness in the effect of preventing the image.

3: Image failure due to toner-fogging drop This is an image failure in which the toner accumulated on the side surface of the photosensitive drum 1 of the control member 5 falls as a toner lump on the surface of the developing roller 2 and the image density becomes abnormally high only at that portion. is there.

4: Toner contamination of the developing device This is a problem that the toner T collected on the side surface of the photosensitive drum 1 of the control member 5 is scattered by the vibration of the control member 5 itself, and the developing device 100 is contaminated by the scattered toner. In particular, the toner in the developing device 100 that has repeatedly performed the image forming operation is likely to be scattered because the external additive is peeled off and the charging ability is lowered.

  In Comparative Example 2, since the end portion length L of the control member 5 is short, the flying toner T accumulates on the surface of the control member 5 from the upstream side in the rotation direction of the developing roller 2, and the above-described problem occurs.

  Here, the relationship between the surface angle area of the developing roller 2 where the control member 5 covers the developing roller coat layer and the toner scattering amount is shown in FIG. The toner scattering amount is obtained by providing a sheet member for collecting the toner scattered outside the developing region 70 and measuring the weight of the toner attached to the sheet member.

  Using the developing device 100 of Example 1, the amount of toner adhering to the surface of the control member 5 when 4000 sheets were passed was measured. The control member end length L of the developing device 100 was arbitrarily changed, and the diameter of the developing roller 2 was compared using an outer diameter of 16 mm and an outer diameter of 12 mm.

  Here, when the toner scattering amount is 20 mg or less, the above-described problem can be prevented until the end of the developing device life. Further, when the surface angle region of the developing roller 2 where the control member 5 covers the developing roller coat layer is 30 ° or less for both the developing roller diameters of 16 mm and 12 mm, the toner scattering amount is 20 mg or more, and the above-described problem occurs. When the angle was 30 ° or more, the toner scattering amount was 20 mg or less, and the above-described problems could be prevented until the end of the developing device life.

  That is, as in Example 3, the surface angle region of the developing roller 2 where the control member 5 covers the developing roller coating layer is 30 ° or more, that is, the intrusion start portion 5b which is the other end of the control member 5 is From the position intersecting with the extension P2 that extends the radius of the developing roller 2 in the direction of 30 °, where the angle connecting the rotation center of the developing roller 2 and the photosensitive drum 1 is 0 ° at an angle of 2 in the reverse rotation direction. The effect of the present invention can be obtained when the distance L from the control member end side 5a is long in the direction along the control member 5.

  Note that the longer the end length L of the control member 5 is, the more difficult it is to obtain the tip position accuracy.

  Table 2 shows a comparison between Example 3 and this comparative example in terms of image defects.

  As shown in Table 2, the scattered toner splashing and toner contamination that occurred near the life of the developing device in this comparative example should be maintained at a level that does not cause any problem until the life of the developing device is reached in Example 3. Can do.

Example 4
In this embodiment, only the arrangement of the flying developer control member 5 is changed in the developing device 100 having the same configuration and setting conditions as in the first embodiment.

  FIG. 8 is an arrangement configuration diagram of the control member 5 viewed from the photosensitive drum 1 side in this embodiment. About the structure and operation | movement of the image development apparatus 100, about the thing similar to Example 1, the description is abbreviate | omitted.

  As a feature of this embodiment, as shown in FIG. 8, only the end portion of the control member 5 in the direction parallel to the developing roller biaxial direction covers the region G of the developing region 70 in the circumferential direction of the developing roller 2. Arranged. The central portion of the control member 5 in the axial direction of the photosensitive drum 1 and the developing roller 2 covers the central portion of the developing area.

  Here, the end portion of the control member 5 in the axial direction of the developing roller 2 means at least the end portion side of the image guarantee area in the developing roller 2.

  Usually, the scattered toner scatters in the direction of the air flow generated by the rotation of the photosensitive drum 1 and the developing roller 2, but the air flow is disturbed by the SD roller or the like at the end. Therefore, the toner near the end is scattered in various directions. Further, the toner scattered from the vicinity of the end portion is not collected again on the developing roller 2 or the photosensitive drum 1 and is easily scattered outside the developing device 100.

  Therefore, as in this embodiment, the end of the flying developer control member 5 in the longitudinal direction covers the developing area 70 that is the area where the scattered toner is generated, so that the scattering from the end of the developing roller 2 occurs. Therefore, it is possible to reduce the amount of toner, and the above-described problems can be reduced.

Example 5
In this embodiment, only the arrangement of the flying developer control member 5 is changed in the developing device 100 having the same configuration and setting conditions as in the first embodiment.

  FIG. 9 is an enlarged view of an end portion of the developing area 70 in this embodiment. About the structure and operation | movement of the image development apparatus 100, about the thing similar to Example 1, the description is abbreviate | omitted.

  As a feature of this embodiment, as shown in FIG. 9, the axial ends of the flying developer control member 54 in the photosensitive drum 1 and developing roller 2 axial direction are refracted to the developing roller 2 side.

  By adopting the configuration as in the present embodiment, the space from the end of the developing roller 2 toward the outside of the developing device 100 is blocked, so that the scattered toner toward the outside of the developing device 100 is not emitted to the outside. Thereby, the above-mentioned image defects are reduced. In particular, it is possible to prevent the developing device from being contaminated by scattered toner.

Example 6
In this embodiment, only the arrangement of the flying developer control member 5 is changed in the developing device 100 having the same configuration and setting conditions as in the first embodiment.

  FIG. 10 is an enlarged configuration diagram of the end portion of the development area 70 in this embodiment. About the structure and operation | movement of the image development apparatus 100, about the thing similar to Example 1, the description is abbreviate | omitted.

  As shown in FIG. 10 as a feature of the present embodiment, the end of the flying developer control member 5 is arranged in contact with or close to the SD rollers 21 provided at both ends of the developing roller 2.

  As a result, the flying developer control member 5 can be stably attached, toner can be prevented from sweeping for a long time, and good image formation can be realized.

  In addition, the scattered toner is not discharged outside. Thereby, the above-mentioned problems are reduced. In particular, it is possible to prevent the developing device from being contaminated by scattered toner.

Example 7
In this embodiment, only the arrangement of the flying developer control member 5 is changed in the developing device 100 having the same configuration and setting conditions as in the first embodiment.

  FIG. 11 is an arrangement configuration diagram of the flying developer control member 5 viewed from the photosensitive drum 1 side in this embodiment. About the structure and operation | movement of the image development apparatus 100, about the thing similar to Example 1, the description is abbreviate | omitted.

  As a feature of this embodiment, as shown in FIG. 11, the width of the flying developer control member 5 in the axial direction of the rotating drum 1 and the developing roller 2 is arranged wider than the length of the toner coat layer on the surface of the developing roller 2, and The flying developer control member 5 was disposed so as to cover the toner coat layer of the developing roller surface 30 degrees or more from the center line segment P from the front end position of the flying developer control member 5. That is, the configuration is a combination of the second and third embodiments.

  Depending on the image forming conditions, even if development is performed in an area larger than the image guarantee area or a toner layer is provided on the developing roller wider than the development area, the flying development is wider than the toner coat layer of the developing roller over a long period of time. Providing the agent control member 5 can more reliably prevent the generation of sweeping toner.

  Here, the effects of Examples 1 to 7 are summarized in Table 3 below together with Comparative Examples 1 and 2.

  From Table 3, as shown in Example 1 or 2, the flying developer control member, which is a plate-like member that enters the developing area, is installed so as to cover the image forming area or the toner coat area in the axial direction of the image carrier. In addition, it is possible to prevent a close-up image from the edge of the image. Further, as in the third embodiment, in the direction in which the control member further intersects the development region, the developer carrier rotation direction 30 ° portion from the straight line connecting the center of the image carrier and the developer carrier from the tip. The developer carrier has a length up to a position intersecting with the radial extension line of the developer carrier, i.e., the length from the portion facing the front end portion of the control member on the developer carrier circumferential surface is the developer carrier and the image carrier. The developer carrier has a length that covers the toner coat layer on the surface of the developer carrier over a region of 30 ° or more in the reverse rotation direction of the developer carrier relative to the center line segment P1 connecting the rotation axes of Even in the final state, it is possible to reduce the contact image from the end portion of the image, uneven contact, and toner scattering. Further, if the axial end portion of the flying developer control member covers the developing area as in the fourth embodiment, toner scattering from the end portion of the developing roller can be reduced. As in the fifth exemplary embodiment, the axial end portion of the flying developer control member is refracted toward the developer carrying member, so that it is possible to effectively prevent a close-up image and toner scattering. As in the sixth embodiment, the end of the flying developer control member keeps the distance between the image carrier and the developer carrier constant, so that the toner scattering generated from the upstream side in the rotation direction of the developing roller can be ensured. Can be prevented. Then, as in Example 7, by multiplying Examples 2 and 3, as shown in Table 3, it was possible to maintain satisfactory image formation until the lifetime of the developing device more completely.

  In the present embodiment, the non-magnetic one-component non-contact developing device has been described. However, in the non-contact developing device having the flying developer control member in the developing region, the above-described effects can be obtained by applying the present invention. it can.

  The dimensions, materials, shapes, and relative positions of the components of the image forming apparatus described above are not intended to limit the scope of the present invention only to those unless otherwise specified.

It is sectional drawing which shows Example 1-Example 7 of the image development apparatus concerning this invention. It is a side view which shows the member structure of the image development area periphery in Example 1 of this invention. It is a front view which shows the member structure of the image development area periphery in Example 1 of this invention. It is explanatory drawing which shows the definition of the image development area | region which concerns on this invention. It is a front view which shows the member structure of the image development area periphery in Example 2 of this invention. It is a side view which shows the member structure of the image development area periphery in Example 3 of this invention. It is a front view which shows the member structure of the image development area periphery in Example 3 of this invention. It is a front view which shows the member structure of the image development area periphery in Example 4 of this invention. It is a partial front view which shows the developer carrier end part structure in Example 5 of this invention. It is a partial front view which shows the developer carrier end part structure in Example 6 of this invention. It is a front view which shows the member structure of the image development area periphery in Example 7 of this invention. 6 is a front view showing a member configuration around a developing region in Comparative Example 1. FIG. 12 is a side view showing a member configuration around a developing region in Comparative Example 2. FIG. 10 is a front view showing a member configuration around a developing region in Comparative Example 2. FIG. It is explanatory drawing which shows the behavior of the developer in a development area. 6 is an explanatory diagram illustrating a behavior of a developer in a development region in Comparative Example 1. FIG. FIG. 6 is an explanatory diagram illustrating a state where scattered toner adheres to a recording material. 6 is a graph showing a relationship between an angle region from a center line of a developer carrying member covered by a flying developer control member and an end toner scattering amount. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus provided with a developing device of the present invention. It is explanatory drawing which shows the state of the sweeping toner in the image development area | region which concerns on a prior art example.

Explanation of symbols

1 Photosensitive drum (image carrier)
2 Development roller (developer carrier)
5 Flying developer control member 70 Developing area 100 Developing device 21 Roll T Toner (Developer)

Claims (6)

A developing container for accommodating a developer, said has a developer bearing member a developer which is a rotating member for carrying the transport, the electrostatic latent image is formed, it is a rotary member carrying the electrostatic latent image The developer carrying member is made to face the image carrier, and an oscillating electric field is formed in the developing area located at the facing portion. The vibrating electric field is carried on the surface of the developer carrying member and conveyed to the developing area. in the developer which is, in a developing device for developing the electrostatic latent image,
In the image guarantee area of the image carrier in a direction parallel to the axial direction of the developer carrier, a plate-like member having a tip portion entering the development area from the upstream in the rotation direction of the image carrier, the development member agent parallel width in the axial direction of the bearing member, have a broader flight developer control member than before Kiga image assurance area in the same direction, the flight in the longitudinal direction of the end portion of the flying developer control member The developing device according to claim 1, wherein a leading end portion of the developer control member is provided so as to protrude downstream in the rotation direction of the image carrier from the leading end portion of the flying developer control member in the image guarantee area .   The flying developer control member enters from the upstream side in the rotation direction of the developer carrying member with one end arranged in the developing region, and the intrusion start portion of the flying developer control member is the development developer. An extension in which the radius of the developer carrier is extended in the direction of 30 ° with the angle connecting the rotation center of the developer carrier and the image carrier as 0 ° at an angle in the reverse rotation direction of the developer carrier. 2. The distance from the end of the flying developer control member existing in the development region in a direction along the flying developer control member from a position intersecting with a portion is longer. Development device. 3. The developing device according to claim 1 , wherein an end portion of the flying developer control member in a longitudinal direction is opposed to an entire region of the developing region in a rotation direction of the developer carrying member. 3. The developing device according to claim 1, wherein an end portion in a longitudinal direction of the flying developer control member has a shape refracted toward the developer carrying member. 3. The development according to claim 1, wherein an end of the flying developer control member in a longitudinal direction is in contact with or close to a member that maintains a constant distance between the image carrier and the developer carrier. apparatus.   An image forming apparatus comprising: an image carrier on which an electrostatic latent image is formed on a surface; and the developing device according to claim 1 that develops the electrostatic latent image.

Images