JP2014115420A - Image forming apparatus and electric resistance recovery method of developer regulation member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus which prevents changes in toner charging property when electric resistance of a developer regulation member changes after use, and an electric resistance recovery method of the developer regulation member.SOLUTION: An image forming apparatus 100 includes: a developer carrier 41; a developer regulation member 43 having a conductive part 43a formed of a resin containing an ion conductive agent or elastomer; first voltage application means 51 for applying a voltage to the developer carrier 41; second voltage application means 52 for applying a voltage to the developer regulation member 43; and control means 111 which applies a voltage to the developer carrier 41 and the developer regulation member 43, while rotation of the developer carrier 41 is stopped. A relation between values of voltage to be applied to the developer carrier 41 and the developer regulation member 43 is opposite to a relation to be obtained during development.

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile apparatus using an electrophotographic method or an electrostatic recording method, and a method for recovering an electric resistance of a developer regulating member used in the developing device.

  In an image forming apparatus such as a printer using an electrophotographic method (electrophotographic process), an electrophotographic photosensitive member (photosensitive member) as an image carrier is uniformly charged, and the charged photosensitive member is selectively exposed. As a result, an electrostatic image is formed on the photoreceptor. The electrostatic image formed on the photoreceptor is developed (visualized) as a toner image with toner by a developing device. The toner image formed on the photoreceptor is transferred to a transfer material such as recording paper or a plastic sheet, and the toner image is transferred to the transfer material by applying heat or pressure to the toner image transferred onto the transfer material. Then, image recording is performed.

  The developing device is disposed in contact with the surface of the developing roller and a roller-shaped developer carrying member (developing roller) disposed in an opening of a developing container (frame body) containing toner, and the developing roller conveys the developing device. A blade-like developer regulating member (regulating blade) that regulates the toner to a certain amount.

  The toner adhering to the surface of the developing roller is removed from the surface of the developing roller and returned to the developing container when passing between the developing roller and the regulating blade as the developing roller rotates. A thin layer is formed on the developing roller. At the same time, the toner is given triboelectric charge (tribo) by friction with the regulating blade. The photoconductor rotates to face the developing roller. Then, in the portion where the developing roller is exposed from the developing container, the toner moves from the developing roller to the photosensitive member according to the electrostatic latent image on the photosensitive member.

  The regulating blade generally includes a blade member that is brought into contact with the developing roller, and a support member that is installed in the developing device so that the blade member is disposed at a predetermined position. As the blade member, a plate-like member formed of an elastic body such as rubber is used, and the blade member is fixed to a predetermined position of a metal support member by bonding with an adhesive or the like. Thereby, the blade member can be easily brought into contact (pressure contact) with the developing roller with uniform pressure over the entire length, and the durability is also good.

  Since the surface of the blade member that is in contact with the developing roller has a function of controlling the frictional charge of the toner, it is also called a “charge control surface”. Such a charge control surface is formed of a material such as urethane rubber, urethane resin, polyamide elastomer or the like for negative (negatively chargeable) toner, and for positive (positively chargeable) toner. A charge imparting layer such as silicone rubber is laminated. Further, since the toner itself does not have magnetism for the non-magnetic toner used for forming a color image, a thin film must be formed on the developing roller by applying a high triboelectric charge to the toner. For this type of non-magnetic toner, materials such as urethane rubber, polyamide resin, polyamide elastomer, silicone rubber, and silicone resin are used as the charge control material, and the charge control surface of the blade member is finished with high surface accuracy. Is used.

  Further, by applying a voltage between the regulating blade and the developing roller, the toner can be charged regardless of the chargeability of the toner.

  By the way, in a developing device with high speed and high durability, the toner deteriorates as the usage amount of the developing device increases, and it becomes difficult to impart an appropriate charge to the toner by the regulating blade at the end of the life. is there.

  On the other hand, in patent document 1, it is proposed to use what was shape | molded with the electroconductive resin or the elastomer as a blade member. This blade member is advantageous in forming a uniform toner layer on the developing roller and giving an appropriate charge to the toner. In addition, this blade member is advantageous for suppressing image defects such as fog (a phenomenon in which toner adheres to non-image portions) and low density even when fine particle toner is used.

JP 2009-3000936 A

  However, when using a blade member containing an ion conductive material as a conductive agent in a resin or elastomer and applying a voltage between the blade member and the developing roller, there are the following problems. all right.

  In other words, in such a configuration, when the blade member is continuously energized, the conductive agent is ion-polarized to increase the electrical resistance of the blade member, making it impossible to give an appropriate charge to the toner. is there. As a result, at the end of the life of the developing device, the toner holding force on the developing roller may be reduced and appear as fog in the image.

  Accordingly, an object of the present invention is to provide an image forming apparatus capable of suppressing a change in charge imparting property to toner due to a change in electrical resistance of a developer regulating member with use, and an electrical property of the developer regulating member. It is to provide a resistance recovery method.

  The above object can be achieved by the image forming apparatus and the method for recovering the electric resistance of the developer regulating member according to the present invention. In summary, the first aspect of the present invention is a rotatable developer carrier that carries a developer for developing an electrostatic image, and a developer regulating member that regulates the developer on the developer carrier. A developer regulating member having a conductive portion formed of a resin or an elastomer containing an ionic conductive agent, a first voltage applying means for applying a voltage to the developer carrying member, and the developer regulating member. A second voltage applying means for applying a voltage; a voltage value applied to the developer carrying member in a state where rotation of the developer carrying member is stopped; and a voltage applied to the developer regulating member. A voltage whose magnitude relationship with the value of the developer is opposite to that when the developer carrying member rotates and performs the development is applied from the first and second voltage applying means to the developer carrying member. And a control means for executing an operation to be applied to each of the developer regulating members. When an image forming apparatus characterized by having a.

  According to a second aspect of the present invention, there is provided a rotatable developer carrying member for carrying a developer for developing an electrostatic image, and a developer regulating member for regulating the developer on the developer carrying member. A developer regulating member having a conductive portion formed of a resin or an elastomer containing an ionic conductive agent, and a method for recovering the electrical resistance of the developer regulating member, wherein the developer carrying member is rotated. In a state in which the developer carrying member is rotated, the developer carrying member rotates and the development value is related to the magnitude relationship between the voltage value applied to the developer carrying member and the voltage value applied to the developer regulating member. A method for recovering the electrical resistance of the developer regulating member is provided, wherein a voltage that is opposite to that when performing the above is applied to the developer carrying member and the developer regulating member.

  According to the present invention, it is possible to suppress a change in the charge imparting property to the toner due to a change in the electrical resistance of the developer regulating member with use.

1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention. 1 is a schematic cross-sectional view of a process cartridge provided in an image forming apparatus according to an embodiment of the present invention. 2 is a schematic cross-sectional view of an example of a contact / separation mechanism between a photosensitive drum and a developing roller of an image forming apparatus according to an embodiment of the present disclosure. FIG. 1 is a block diagram illustrating a schematic control mode of a main part of an image forming apparatus according to an embodiment of the present invention. FIG. 6 is a timing chart during a printing operation according to the first exemplary embodiment. FIG. 10 is a timing chart during a printing operation in Comparative Examples 1 and 2. It is a graph which shows transition of the electric current which flows into the control blade in Example 1 and Comparative Example 1. FIG. It is a graph which shows transition of fog in Example 1 and Comparative Example 1. FIG. 10 is a timing chart during a printing operation according to the second exemplary embodiment. FIG. 10 is a timing chart during a printing operation according to the third exemplary embodiment. FIG. 10 is a timing chart during the recovery operation of the regulating blade in the fourth embodiment. FIG. 10 is a timing chart during the recovery operation of the regulating blade in the fifth embodiment. FIG. 10 is a timing chart during a printing operation in Embodiment 6.

  Hereinafter, the image forming apparatus and the developer regulating member electrical resistance recovery method according to the present invention will be described in more detail with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the scope to the following embodiments.

[First Embodiment]
1. First, the overall configuration and operation of an image forming apparatus according to an embodiment of the present invention will be described. FIG. 1 is a schematic cross-sectional view showing a schematic configuration of an image forming apparatus 100 of the present embodiment.

  The image forming apparatus 100 includes a photosensitive drum 1 that is a drum-shaped electrophotographic photosensitive member (photosensitive member) as an image carrier. The photosensitive drum 1 is rotationally driven at a predetermined process speed (peripheral speed) in the direction of arrow R1 in the figure with the rotation axis as the center. The surface of the photosensitive drum 1 is charged by a charging roller 2 that is a roller-type charging member as a charging unit. The charging roller 2 is disposed in contact with the surface of the photosensitive drum 1 and is rotated following the rotation of the photosensitive drum 1 in the direction of the arrow R1 in the drawing. A charging voltage (charging bias) composed of, for example, a DC voltage is applied to the charging roller 2 by a charging power source (not shown) as voltage applying means (bias applying means). As a result, the surface of the photosensitive drum 1 is substantially uniformly charged to a predetermined potential having a predetermined polarity.

  The surface of the photosensitive drum 1 after the charging process is exposed according to image information by an exposure device 3 as an exposure unit, and an electrostatic latent image (electrostatic image) is formed. The exposure device 3 includes a laser scanner, a polygon mirror, a reflection lens, and the like, irradiates the surface of the photosensitive drum 1 with laser light based on image information, removes the charge of the irradiated portion, and generates an electrostatic latent image. Form.

  The electrostatic latent image formed on the surface of the photosensitive drum 1 is developed (visualized) as a toner image by attaching a toner as a developer by a developing device 4 as a developing unit. In the present embodiment, the toner charged with the same polarity as the charging polarity (negative polarity in the present embodiment) of the photosensitive drum 1 is exposed to the exposed portion where the absolute value of the potential is reduced by being exposed after being uniformly charged. And the electrostatic latent image is developed (reversal development).

  The toner image formed on the surface of the photosensitive drum 1 is transferred onto the transfer material P by a transfer roller 5 which is a roller-type transfer member as transfer means. The transfer roller 5 is pressed toward the photosensitive drum 1 to form a nip (transfer nip) which is a contact portion between the photosensitive drum 1 and the transfer roller 5 at the transfer portion N. The transfer material P is accommodated in a transfer material accommodating portion (such as a tray or a cassette) 7 and is transferred in synchronization with the toner image on the photosensitive drum 1 by conveying means such as a transfer material supply roller 8 and a registration roller 9. Part N is supplied. The transfer roller 5 is charged with a toner charging polarity (regular charging polarity: negative polarity in this embodiment) of a toner image on the photosensitive drum 1 by a transfer power source (not shown) as a voltage applying unit (bias applying unit). A transfer voltage (transfer bias) having a polarity opposite to that of the above is applied. As a result, the toner image on the photosensitive drum 1 is transferred onto the transfer material P.

  The toner (transfer residual toner) remaining on the surface of the photosensitive drum 1 after the transfer of the toner image is cleaned by a cleaning device 6 as a cleaning unit. The cleaning device 6 removes the transfer residual toner from the surface of the rotating photosensitive drum 1 by a cleaning blade 61 as a cleaning member, and collects it in a recovery toner container 62. Thereafter, the photosensitive drum 1 is used for the next image formation.

  On the other hand, the transfer material P after the toner image is transferred is conveyed to a fixing device 10 as a fixing unit, and heated and pressed by a fixing roller and a pressure roller of the fixing device 10, so that the surface of the transfer material P is transferred. The toner image is fixed. The transfer material P after the toner image is fixed is discharged outside the apparatus main body 11 of the image forming apparatus 100. Thereby, a series of image forming operations is completed.

  In the present embodiment, the photosensitive drum 1 and the charging roller 2, the developing device 4, and the cleaning device 6 as process means that act on the photosensitive drum 1 are integrally configured by a frame and are attached to and detached from the apparatus main body 11. The process cartridge 12 is possible. The process cartridge 12 can be attached to and detached from the apparatus main body 11 via mounting means such as a positioning portion and a mounting guide section provided in the apparatus main body 11. Further, as is well known to those skilled in the art, the process cartridge 12 is driven through a coupling or a contact provided in the process cartridge 12 and the apparatus main body 11 in a state where the process cartridge 12 is mounted at a predetermined position of the apparatus main body 11. Force transmission and voltage application are possible.

2. Next, the overall configuration of the process cartridge 12 in this embodiment will be described.

  FIG. 2 is a schematic cross-sectional view of the process cartridge 12 as viewed along the longitudinal direction (rotational axis direction) of the photosensitive drum 1.

  The process cartridge 12 is configured integrally by connecting a cleaning frame 12a and a developing frame 12b. As will be described later, the cleaning frame 12a and the developing frame 12b are frames that support various elements. The cartridge frame that is the frame of the process cartridge 12 is formed by the cleaning frame 12a and the developing frame 12b. It is configured.

  The photosensitive drum 1 is rotatably attached to the cleaning frame 12a via a bearing (not shown). The photosensitive drum 1 is rotationally driven in the direction of an arrow R1 in the drawing according to an image forming operation by transmitting a driving force of a driving motor 53 (FIG. 4) as a driving means (driving source). In the present embodiment, the photosensitive drum 1 is an organic photosensitive drum in which an aluminum cylinder cylinder is coated with a functional undercoat layer, a carrier generation layer, and a carrier transfer layer in this order.

  Further, the cleaning frame 12 a includes the charging roller 2 and the cleaning device 6. That is, the charging roller 2 is rotatably supported by the cleaning frame 12a so as to contact the peripheral surface of the photosensitive drum 1. A cleaning blade 61 of the cleaning device 6 is supported on the cleaning frame 12a so as to be in contact with the peripheral surface of the photosensitive drum 1, and a collected toner container 62 of the cleaning device 6 is formed by the cleaning frame 12a. ing. The transfer residual toner removed from the surface of the photosensitive drum 1 by the cleaning blade 61 falls into the collected toner container 62 and is stored.

  Here, the charging roller 2 has a roller portion (elastic layer) 22 formed of conductive rubber in contact with the peripheral surface of the photosensitive drum 2 at a predetermined pressure, and is driven by the rotation of the photosensitive drum 1. Rotate. A predetermined DC voltage is applied to the metal core 21 of the charging roller 2 during the charging process, whereby a uniform dark portion potential (Vd) is formed on the surface of the photosensitive drum 1. The surface of the photosensitive drum 1 is exposed with a spot pattern of laser light emitted from the exposure device (scanner unit) 3 in accordance with the image data. The exposed portion of the surface of the photosensitive drum 1 loses its charge due to carriers from the carrier generation layer, and the absolute value of the potential decreases. As a result, an electrostatic latent image is formed on the photosensitive drum 1 with a predetermined light portion potential (Vl) at an exposed portion and a predetermined dark portion potential (Vd) at an unexposed portion.

  On the other hand, the developing frame 12b constitutes a developing container including a developing chamber 4a of the developing device 4 and a developer storage chamber (toner storage chamber) 4b.

  In the developing chamber 4a, a developing roller 41 as a developer carrying member, a supply roller 42 as a developer supplying member, and a regulating blade 43 as a developer regulating member are arranged.

  The supply roller 42 is in contact with the peripheral surface of the developing roller 41 with a predetermined pressure, and a nip (supply nip) Nd is formed at a contact portion with the developing roller 41. The supply roller 42 is rotationally driven in the direction of the arrow R3 in the figure by transmitting the driving force of a driving motor as driving means (not shown). The supply roller 42 is an elastic sponge roller in which an elastic layer 42b made of a foam is formed on the outer periphery of a conductive core metal 42a. The supply roller 42 and the developing roller 41 are in contact with each other with a predetermined intrusion amount ΔE. Here, the intrusion amount ΔE is an amount by which the supply roller 42 is concaved by the developing roller 41, and the value obtained by adding the radius of the developing roller 41 and the radius of the supply roller 42 is the supply amount of the developing roller 41 and the supply roller 42. It is represented by a value obtained by subtracting the distance between the rotation centers with the roller 42. The developing roller 41 and the supply roller 42 rotate with a circumferential speed difference in opposite directions at the contact portion Nd. As a result, the supply roller 42 supplies toner to the developing roller 41 and removes the toner from the developing roller 41. Note that by adjusting the potential difference between the supply roller 42 and the developing roller 41 at that time, it is possible to adjust the amount of toner supplied to the developing roller 41 and the amount of peeling from the developing roller 41.

  The regulating blade 43 is disposed above the developing roller 41 in the drawing and abuts the circumferential surface of the developing roller 41 with a predetermined pressure so that the tip (free end) faces the upstream side in the rotation direction of the developing roller 41. (Counter contact). The regulating blade 43 regulates the coating amount of the toner supplied onto the developing roller 41 by the supply roller 42 to a predetermined amount, and applies a charge to the toner by friction.

  The developing roller 41 is an elastic rubber roller in which an elastic layer 41b made of rubber is formed on the outer periphery of a conductive core metal 41a. The developing roller 41 receives the driving force of a driving motor 54 (FIG. 4) as a driving unit, so that the surfaces of the developing roller 41 are in the same direction (the direction from the top to the bottom in the figure) at the portion facing the photosensitive drum 1. Is driven to rotate.

  In the present embodiment, when the process cartridge 12 is mounted on the apparatus main body 11, the developing roller 41 and the photosensitive drum 1 are substantially in contact with each other only during image formation. In a normal state such as a standby state of the image forming apparatus 100, the developing roller 41 and the photosensitive drum 1 are separated from each other. Therefore, the image forming apparatus 100 includes a contact / separation mechanism as a contact / separation unit that makes the developing roller 41 contact or separate from the photosensitive drum 1. As the abutment / separation mechanism, any available configuration can be used. For example, as shown in FIG. 3, the cleaning frame 12a of the process cartridge 12 is coupled to the developing frame 12b so as to be rotatable about a rotation shaft 12c. As shown in FIG. 3A, the developing frame 12b is moved in the direction indicated by the arrow R5 by the biasing force of the compression coil spring 12d as the biasing means provided between the cleaning frame 12a and the developing frame 12b. And the developing roller 41 is brought into contact with the photosensitive drum 1. The developing frame 12b is provided with a drive receiving portion 12e constituting the contact / separation mechanism 55, and the apparatus main body 11 is provided with the drive portion 13 constituting the contact / separation mechanism 55. Then, as shown in FIG. 3B, the drive receiving portion 12 e is pushed up by the drive portion 13, thereby rotating the developing frame 12 b in the direction of the arrow R <b> 6 and separating the developing roller 41 from the photosensitive drum 1. .

  In the present embodiment, the developing roller 41 is connected to a developing power source 51 (FIG. 4) as a voltage applying unit (bias applying unit), and the developing power source 51 supplies the developing roller 41 with a predetermined DC voltage. A voltage (development bias) can be applied. The toner carried on the developing roller 41 that is negatively charged by frictional charging is formed between the photosensitive drum 1 and the developing roller 41 in the developing portion G where the photosensitive drum 1 and the developing roller 41 abut. Due to the potential difference, the light is transferred only to the bright portion potential portion on the photosensitive drum 1. As a result, the electrostatic latent image on the photosensitive drum 1 is developed (visualized). In the present embodiment, generally, −300 V is applied to the developing roller 41 when the developing roller 41 is rotationally driven. The voltage applied to the developing roller 41 will be described in detail later.

The volume resistance of the developing roller 41 is preferably 1 × 10 ⁹ Ω or less. If the volume resistance of the developing roller 41 is greater than 1 × 10 ⁹ Ω, the developing bias voltage value on the surface of the developing roller 41 decreases, the DC electric field in the developing portion G decreases, and the developing efficiency decreases. The image density may decrease. Further, the volume resistance of the developing roller 41 is usually 1 × 10 ⁴ Ω or more. The volume resistance of the developing roller 41 was calculated by providing an electrical resistance of 10 kΩ on the ground side and measuring the voltage at both ends to calculate the current.

  The toner storage chamber 4b is disposed behind the developing chamber 41 with respect to the photosensitive drum 1 and stores toner therein. The toner chamber 4b is an opening provided in a partition wall between the developing chamber 4a and the developing chamber. It communicates with 4a. A stirring and conveying member 44 is provided in the toner storage chamber 4b. The agitating / conveying member 44 is rotationally driven in the direction of arrow R4 in the drawing to agitate the toner stored in the toner storage chamber 4b and to convey the toner toward the supply roller 42 in the developing chamber 4a.

3. Toner Next, the toner used in this embodiment will be described. The toner used in the present embodiment is a non-magnetic one-component developer manufactured by an emulsion polymerization method, and has a property of being negatively charged by frictional charging. The toner has a volume average particle size of 6 μm, and includes silicon oxide (silica) particles as an insulating external additive, and titanium oxide particles as a conductive external additive having a higher conductivity than this. Externally added.

Here, in general, the conductive external additive has a volume resistivity of 1 × 10 ¹² Ω · cm or less, and the insulating external additive has a volume resistivity higher than that. For example, a conductive external additive having a volume resistivity of 1 × 10 ⁻⁶ Ω · cm or less and an insulating external additive having a higher volume resistivity can be used. Further, the volume resistivity of the conductive external additive is usually 1 × 10 ⁻⁹ Ω · cm or more, and the volume resistivity of the insulating external additive is usually 1 × 10 ²² Ω · cm or less. . Further, an external additive can be externally added in the range of 5 to 10 parts by mass with respect to 100 parts by mass of the resin toner particles.

  By externally adding a highly conductive conductive additive, it is possible to reduce the electrical resistance of the toner, and even between the regulating blade 43 and the developing roller 41 even when the developing roller 41 is not driven to rotate. Current flows due to the potential difference.

  Examples of the conductive external additive include titanium oxide, aluminum oxide, zinc oxide, cerium oxide, tin oxide, strontium titanate, and the toner includes at least one of these (one type alone or two or more types). In combination). In this embodiment, titanium oxide particles are externally added to the toner as a conductive external additive.

Further, the method for reducing the electrical resistance of the toner is not limited to the external addition of an external additive, but a conductive internal additive such as conductive carbon black or conductive magnetic particles may be added to the toner. You may do it. Generally, the volume resistivity of the conductive internal additive is 1 × 10 ¹² Ω · cm or less, and usually 1 × 10 ⁻⁹ Ω · cm or more. In this case, the internal additive can be internally added in the range of 5 to 10 parts by mass with respect to 100 parts by mass of the resin toner particles.

3. Regulation Blade Next, the regulation blade 43 used in this embodiment will be described in more detail.

  The regulating blade 43 used in the present embodiment includes a blade member (conductive portion) 43a that abuts the developing roller 41 over its entire length in the longitudinal direction, and a support member 43b that supports the blade member 43a (FIG. 2). ). The regulating blade 43 regulates the amount of toner that is carried out from the developing container 4b.

  As described above, the leading end (free end) of the regulating blade 43 is in contact with the developing roller 41 so that the leading end (free end) faces the upstream side with respect to the rotation direction of the developing roller 41 (counter contact). Contact). The contact portion of the regulation blade 43 with the developing roller 41 is located downstream of the contact portion Nd between the developing roller 41 and the supply roller 42 in the rotation direction of the developing roller 41. In the present embodiment, the regulating blade 43 is arranged so that the tip thereof faces downward.

  The material of the support member 43b may be any metal or resin. Specific examples include metals such as stainless steel (SUS), phosphor bronze, and aluminum, and resins such as polyethylene terephthalate, acrylic, polyethylene, and polyester. A conductive material can be added to such a resin. The support member 43b can be a flat plate shape or a curved plate shape obtained by bending the flat plate shape. In the present embodiment, a metal plate-like member, in particular, a support member 43b formed of SUS sheet metal is used.

  And in this embodiment, the blade member 43a is shape | molded and integrated at the front-end | tip (free end) side of the support member 43b. In the present embodiment, the blade member 43a is formed of a resin or an elastomer, and has conductivity by containing an ionic conductive agent. The regulating blade 43 is in contact with the peripheral surface of the developing roller 41 at the edge portion on the distal end (free end) side of the blade member 43a and / or the surface on the developing roller 41 side in a predetermined range from the edge portion to the proximal end portion side. .

The conductivity of the blade member 43a can be adjusted according to the type of resin or elastomer used, the conductive agent, and the amount of stitches. The volume resistance value of the blade member 43a is preferably 10 ⁸ Ω or less. By setting it within this range, it is possible to improve the charge imparting property to the toner. The volume resistance value of the blade member 43a is usually 10 ³ Ω or more. In the present embodiment, the volume resistance value of the molded body of the blade member 43a is 10 ⁶ Ω. Here, as the volume resistance value of the molded body of the blade member 43a, a measurement value by a measurement method according to JIS K6911 can be adopted.

  Examples of the resin or elastomer that is preferably used together with a conductive agent include polyester, polyester elastomer, polyethylene terephthalate, polyurethane, silicone rubber, silicone resin, polyamide, polyamide elastomer, and melamine resin. In this embodiment, a polyester elastomer is used.

  In addition, as an ionic conductive conductive agent (ionic conductive agent), a cationic surfactant such as lauryltrimethylammonium chloride, an amphoteric surfactant such as laurylbetaine, and a quaternary ammonium salt such as tetraethylammonium perchlorate. And organic acid lithium salts. In this embodiment, a sulfonate such as an imide lithium salt is used. These can be used alone or in combination of two or more.

  More specifically, in this embodiment, the support member 43b has a thickness of 0.1 mm, a length of 230 mm in the longitudinal direction (substantially parallel to the rotation axis direction of the developing roller 41), and a length of 15 mm in the short direction. It is made of sheet metal. A blade member 43a having a thickness of 0.5 mm, a length of 230 mm in the longitudinal direction (substantially parallel to the rotation axis direction of the developing roller 41), and a length of 3 mm in the short direction is formed on the free end side of the support member 43b. Have been integrated. Of the length in the short direction of the support member 43b, 2.5 mm on the free end side is covered with the blade member 43a.

  The regulation blade 43 is connected to a regulation power source 52 (FIG. 4) as voltage application means (bias application means), and a regulation voltage (regulation bias) which is a predetermined DC voltage from the regulation power source 52 to the regulation blade 43. Can be applied. In the present embodiment, the regulation bias is applied to the blade member 43a via the support member 43b.

  In the present embodiment, generally, −500 V is applied to the regulating blade 43 when the developing roller 41 is rotationally driven. As described above, −300 V is applied to the developing roller 41 at this time. Therefore, the toner coat on the developing roller 41 is stabilized by the potential difference between the developing roller 41 and the regulating blade 43 while receiving frictional charging at the nip portion between the developing roller 41 and the blade member 43a of the regulating blade 43. .

  At this time, a current flows from the developing roller 41 to the regulating blade 43 due to a potential difference between the developing roller 41 and the regulating blade 43. That is, the developing roller 41 has a high potential on the positive polarity (opposite polarity to the normal charging polarity of the toner of the present embodiment), and the regulating blade 43 has the negative polarity (normal charging polarity of the toner of the present embodiment). High potential. When energized continuously in such a state, ions in the blade member 43a of the regulating blade 43 may be unevenly distributed or ion hyperpolarization may occur (these are also simply referred to as “ion polarization”). is there. Therefore, as described above, the electrical resistance of the blade member 43a increases, and it may not be possible to give an appropriate charge to the toner. As a result, at the end of the life of the developing device 4, the toner holding force to the developing roller 41 may be reduced and appear as fog in the image.

  Therefore, one of the objects of the present embodiment is to suppress the change in the charge imparting property to the toner due to the change in the electrical resistance of the regulating blade 43 with use. One of the more detailed purposes of this embodiment is to suppress fogging until the end of the life of the developing device 4 even when an ion conductive material is used as the conductive agent for the blade member 43a of the regulating blade 43. It is.

4). Voltage control (electric resistance recovery method for developer regulating member)
With respect to the above-described problem, in the present embodiment, when the rotation of the developing roller 41 is stopped, the developing roller 41 and the regulating blade 43 are subjected to development (the developing roller 41 rotates and performs development). The control is executed to apply a voltage having a value opposite to the magnitude relationship. In other words, when the rotation of the developing roller 41 is stopped, the potential difference between the developing roller 41 and the regulating blade 43 is the time when an image is formed (when the developing roller 41 rotates and performs development). Control to make the polarity reverse (the direction of the electric field is reversed) is executed. As a result, a current in the opposite direction to that during image formation flows through the regulating blade 43 (hereinafter, this operation is also referred to as “recovery operation”). As a result, ion polarization of the blade member 43a of the regulating blade 43 due to continuous energization can be suppressed, and an increase in electrical resistance of the regulating blade 43 can be suppressed. More detailed control will be described later in detail with reference to the embodiment.

5. Control Mode FIG. 4 shows a schematic control mode of the main part of the image forming apparatus 100 of the present embodiment. The control unit 101 includes a CPU 111 as a control unit that is a central element that performs arithmetic processing, a ROM 112 and a RAM 113 as storage units, and the like. A RAM 113 which is a rewritable memory stores information input to the control unit 101, detected information, calculation results, and the like, and a ROM 112 stores a control program, a data table obtained in advance, and the like. The CPU 111, the ROM 112, and the RAM 113 can transfer and read data from each other.

  The CPU 111 controls each part of the image forming apparatus 100 according to the contents of the control program stored in the ROM 112 to perform a sequence operation. In relation to the present embodiment, the CPU 111 controls ON / OFF and output values of the development power source (first voltage application unit) 51 and the regulation power source (second voltage application unit) 52. The CPU 111 controls ON / OFF of the drive motor 53 for the photosensitive drum 1 and the drive motor 54 for the developing roller 42. Further, the CPU 111 performs control to switch the contact or separation state of the developing roller 42 with respect to the photosensitive drum 1 by the contact / separation mechanism 55.

  Further, an external host device (not shown) such as an image reading device or a personal computer is connected to the apparatus main body 11 of the image forming apparatus 100, and image data is transferred from the host apparatus to the control unit 101 of the apparatus main body 10. Various information signals such as are input.

6). Next, the control of the voltage applied to the developing roller 41 and the regulating blade 43 will be described in more detail with reference to examples, comparative examples, and experimental examples using them.

Example 1
In the present embodiment, after the developing roller 41 is stopped, the voltage is continuously applied to the developing roller 41 for a certain time after the application of the voltage to the regulating blade 43 is stopped. In the toner used in this embodiment, since a conductive external additive is externally added, a current flows from the regulating blade 43 to the developing roller 41. Thereby, it becomes possible to suppress the ion polarization of the blade member 43a of the regulating blade 43 due to continuous energization, and it is possible to suppress an increase in the electrical resistance of the regulating blade 43.

  On the other hand, if the voltage is applied to the developing roller 41 for a certain period of time after the application of the voltage to the regulating blade 43 is stopped while the developing roller 41 is rotationally driven, the details will be described later. The toner falls from the developing roller 41.

  FIG. 5 is a timing chart at the time of the printing operation in the present embodiment (the lower part of the figure shows the applied voltage value at the corresponding timing in the upper part of the figure). Here, the printing operation (or job) refers to a series of image forming operations on one or a plurality of transfer materials according to one image formation start instruction.

  When a print signal (image formation operation start instruction) is input to the image forming apparatus 100 and a print operation is started, first, the rotational driving of the photosensitive drum 1 is started (t1). Thereafter, application of a predetermined voltage to the developing roller 41 and the regulating blade 43 is started (t2). In this embodiment, −300 V is applied to the developing roller 41 and −500 V is applied to the regulating blade 43. After the voltage application is started, the rotation of the developing roller 41 is started (t3), and then the photosensitive drum 1 and the developing roller 41 are brought into contact with each other (t4). Image formation is performed in this contact state, and after the image formation is completed, the photosensitive drum 1 and the developing roller 41 are separated (t5). Thereafter, the rotational driving of the developing roller 41 is stopped (t6), and then the voltage application to the regulating blade 43 is stopped (t7). At this time, the voltage is applied only to the developing roller 41, and a current flows from the regulating blade 43 to the developing roller 41. That is, the regulating blade 43 has a high potential on the positive polarity (opposite polarity to the normal charging polarity of the toner of the present embodiment), and the developing roller 41 has the negative polarity (normal charging polarity of the toner of the present embodiment) side. High potential. After a predetermined time has elapsed, the application of voltage to the developing roller 41 is stopped (t8), and then the rotational driving of the photosensitive drum 1 is stopped (t9).

  In this embodiment, after the application of the voltage to the regulating blade 43 is stopped, −300 V is continuously applied to the developing roller 41 for 2 seconds so that a current flows from the regulating blade 43 to the developing roller 41.

  Here, the current flowing in the direction from the developing roller 41 to the regulating blade 43 is defined as the forward current (sign is +), and the current flowing in the direction from the regulating blade 43 to the developing roller 41 is defined as the reverse current (sign is-). To do. In this embodiment, a current of +3.0 μA flows through the regulating blade 43 during image formation. When a voltage is applied only to the developing roller 41 after the developing roller 41 is stopped, a current of −1.0 μA flows through the regulating blade 43.

  As described above, when the developing roller 41 is stopped, by allowing the current to flow in the direction opposite to that at the time of image formation to flow through the regulating blade 43, it becomes possible to suppress the ion polarization of the blade member 43a, and the life of the developing device 4 Conductivity can be maintained until the end.

  Here, when an excessive voltage is applied between the developing roller 41 and the regulating blade 43 and a leak occurs, an excessive current flows unnecessarily although it does not contribute to suppression of ion polarization of the blade member 43a. End up. Therefore, the voltage applied when a current in the direction opposite to that during image formation is applied to the regulating blade 43 is a voltage within a range where current flows between the developing roller 41 and the regulating blade 43 and no leakage occurs. It is desirable.

  Note that the applied voltage value, the applied current value, the application time, and the like when a current in the reverse direction flows through the regulating blade 43 can have the desired effect depending on the life of the developing device 4, the configuration of the regulating blade 43, and the like. It can be changed as appropriate.

(Comparative Example 1)
FIG. 6A is a timing chart at the time of a printing operation in this comparative example (the lower part of the figure shows the applied voltage value at the corresponding timing in the upper part of the figure).

  In this comparative example, after the developing roller 41 is stopped, the voltage application to the regulating blade 43 and the developing roller 41 is stopped simultaneously. Therefore, the current in the direction opposite to that at the time of image formation does not flow through the regulating blade 43. Other operations are the same as those in the first embodiment.

(Comparative Example 2)
FIG. 6B is a timing chart during the printing operation in this comparative example (the lower part of the figure shows the applied voltage value at the corresponding timing in the upper part of the figure).

  In this comparative example, when the developing roller 41 is driven to rotate, the application of voltage to the regulating blade 43 is stopped and the voltage is applied only to the developing roller 41. Other operations are the same as those in the first embodiment.

(Experimental example 1)
<Experiment method>
In order to confirm the effect of Example 1, the following three experiments (1) to (3) were performed. The evaluation condition was that an image forming apparatus having a nominal life of 7000 sheets was intermittently passed through a horizontal line print (low image ratio print) with an image ratio of 1% in an evaluation environment of 10.0 ° C. and 10% Rh. . Here, intermittent paper passing means that the next printing is performed after a standby state after printing.

(1) Toner Drop from Developing Roller Evaluation of toner dropping from the developing roller 41 is performed by observing the dropping state of the toner from the developing roller 41 when a low image ratio print is intermittently passed. went. The evaluation criteria are as follows.
A: No toner drop occurred B: Toner fall occurred

(2) Electrical resistance change of the regulation blade The electrical resistance change of the regulation blade 43 is evaluated by measuring the current flowing through the regulation blade 43 periodically when a low image ratio print is intermittently passed. went.

(3) Fog Evaluation of the fog was performed by periodically measuring the fog on the evaluation paper when the low image ratio print was intermittently passed. The fog measurement method is as follows. First, the average reflectivity Dr (%) of the evaluation paper before passing through and the reflectivity Ds (%) of the white background portion after passing through are each measured by a reflectometer (“REFLECTOMETER MODEL TC-” manufactured by Tokyo Denshoku Co., Ltd.). 6DS "). Next, the fog (%) was calculated from the obtained Dr and Ds using the following formula, and 3% or less was evaluated as a good image quality as an evaluation standard.
Fog (%) = Dr (%)-Ds (%)

  <Experimental result>

  Table 1 shows the evaluation results of Experiment (1). In Example 1 and Comparative Example 1, toner did not fall during the passing of the paper, but in Comparative Example 2, the toner dropped when 100 sheets were passed. This is because if a current in the reverse direction is passed through the regulating blade 43 during the rotation of the developing roller 41, the toner on the developing roller 41 passes through the regulating blade 43 without obtaining a predetermined charge. . On the other hand, in Example 1, since a current in the reverse direction flows through the regulating blade 43 when the developing roller 41 is stopped, low-charge toner does not go out of the developing container 12b. No toner drop from the developing roller 41 as seen in Example 2 was observed. Thus, it was found that the developing roller 41 needs to be stopped when a current in the reverse direction is passed through the regulating blade 43.

  FIG. 7 shows the transition of the current flowing through the regulating blade 43 during image formation in Example 1 and Comparative Example 1 regarding Experiment (2). In the initial use state of the developing device 1, the current flowing through the regulating blade 43 was equal to +3.0 μA in both Example 1 and Comparative Example 1. However, in Comparative Example 1, the current decreased to +1.5 μA after passing 7000 sheets. On the other hand, in Example 1, it was settled in the fall to about +2.0 microampere. As described above, it was confirmed that a change in electric resistance of the regulating blade 43 was suppressed by flowing a current in the reverse direction to the regulating blade 43. In Comparative Example 2, since the toner dropped, the current flowing through the regulating blade 43 could not be measured.

  Table 2 shows the evaluation result of Experiment (3) (3% or less is good image quality). FIG. 8 shows the transition of fog in Example 1 and Comparative Example 1. In Example 1, the fog was as good as 2% after passing 7000 sheets, but in Comparative Example 1, the fog was 6% after passing 7000 sheets, which deteriorated in the second half of the life. This is because the charging performance of the regulating blade 43 is lowered due to the increase in electrical resistance of the regulating blade 43, and the toner on the developing roller 41 cannot obtain a predetermined charge. In this way, by causing a current in the reverse direction to flow through the regulating blade 43 while the developing roller 41 is stopped, it is possible to suppress a change in the electrical resistance of the regulating blade 43 until the latter half of the life and to suppress fogging. I understood. In Comparative Example 2, fogging could not be evaluated because toner fall occurred.

  Table 3 shows the results of evaluating the fog when only the external additive and the internal additive of the toner in Example 1 were changed. Like the toners 1 to 5, the toner in which a conductive external additive is added to the toner further reduces the charging performance of the regulating blade 43 due to the increase in the electrical resistance of the regulating blade 43 until the latter half of the life, as in the first embodiment. It was possible to suppress well and to suppress fogging. Further, the same effects as in Example 1 could be obtained even with toner in which conductive particles were internally added, such as toners 6-7. On the other hand, in the toner in which only the insulating external additive, silica, was added without adding conductive particles to the toner, fogging deteriorated in the latter half of the life. Thus, it was found that when only the insulating silica was externally added, current hardly flows even when -300 V was applied when the developing roller 41 was stopped, and it was difficult to suppress the change in the electric resistance of the regulating blade 43. However, depending on the setting of the voltage to be applied, the electrical resistance change of the regulating blade 43 may be suppressed to some extent.

  As described above, according to the first embodiment, the image forming apparatus 100 includes the rotatable developer carrying member 41 that carries the developer for developing the electrostatic image. Further, the image forming apparatus 100 is a developer regulating member 43 that regulates the developer on the developer carrying member, and includes a conductive portion 43a formed of a resin or an elastomer containing an ionic conductive agent. 43. In addition, the image forming apparatus 100 includes a first voltage applying unit 51 that applies a voltage to the developer carrier 41 and a second voltage applying unit 52 that applies a voltage to the developer regulating member 43. The image forming apparatus 100 further includes a control unit 111 that executes the following recovery operation. In the recovery operation, when the rotation of the developer carrier 41 is stopped, the magnitude relationship between the values of the voltages applied to the developer carrier 41 and the developer regulating member 43 is as follows. Is applied to the developer carrier 41 and the developer regulating member 43, respectively.

  Thereby, according to Example 1, the electrical resistance change of the control blade 43 can be suppressed and fogging can be suppressed.

(Example 2)
FIG. 9 is a timing chart at the time of a printing operation in this embodiment (the lower part of the figure shows the applied voltage value at the corresponding timing in the upper part of the figure).

  In this embodiment, after the developing roller 41 is stopped, the voltage is continuously applied to the regulating blade 43 for a certain period of time, and the voltage applied to the developing roller 41 is more negative than the voltage applied to the regulating blade 43 ( The toner is increased to the normal charging polarity) side of the toner of this embodiment. Specifically, the voltage of −500 V was continuously applied to the regulating blade 43, and the voltage applied to the developing roller 41 was switched from −300V at the time of image formation to −800V. As a result, a current in the direction opposite to that at the time of image formation flows through the regulating blade 43.

  Also in this example, the same effect as in Example 1 could be obtained.

(Example 3)
FIG. 10 is a timing chart at the time of a printing operation in the present embodiment (the lower part of the figure shows the applied voltage value at the corresponding timing in the upper part of the figure).

  In this embodiment, the application of voltage to the developing roller 41 is stopped for a certain period of time after the developing roller 41 is stopped, and the regulating blade 43 has a positive polarity (opposite to the regular charging polarity of the toner of the present embodiment). The voltage of was applied. This voltage is opposite in polarity to the voltage applied to the regulating blade 43 during image formation. Specifically, the voltage applied to the regulating blade 43 was switched from −500 V at the time of image formation to +300 V. As a result, a current in the direction opposite to that at the time of image formation flows through the regulating blade 43.

  Also in this example, the same effect as in Example 1 could be obtained.

Example 4
FIG. 11 is a timing chart during the recovery operation of the regulating blade 43 in this embodiment (the lower part of the figure shows the applied voltage value at the corresponding timing in the upper part of the figure).

  In Examples 1 to 3, the recovery operation of the regulating blade 43 was performed following the printing operation.

  On the other hand, in this embodiment, a voltage having a negative polarity (a normal charging polarity of the toner of the present embodiment) is applied to the developing roller 41 during a standby time for printing. Here, “waiting for printing” refers to a state in which the image forming apparatus 100, more specifically, the CPU 111 serving as its control means, is waiting for an input of a print signal (image formation start instruction).

  Specifically, the same voltage of −300 V as that applied to the developing roller 41 during image formation was applied to the developing roller 41. As a result, a current in the direction opposite to that at the time of image formation flows through the regulating blade 43. At this time, the photosensitive drum 1 and the developing roller 41 are stopped, the photosensitive drum 1 and the developing roller 41 are separated from each other, and application of voltage to the regulating blade 43 is stopped.

  Also in this example, the same effect as in Example 1 could be obtained.

  Thus, the recovery operation of the regulating blade 43 according to the present invention can be performed at an arbitrary timing during non-image formation. Examples of non-image formation include the following in addition to the above-described print standby. There is a multi-rotation operation before a predetermined preparation operation is performed, such as when the image forming apparatus is turned on or when the image forming apparatus is returned from the sleep mode. In addition, there is a pre-rotation operation in which a predetermined preparation operation is executed from when a print signal (image formation start instruction) is input to when an image corresponding to image information is actually written. In addition, there is a corresponding paper interval between transfer materials during continuous image formation. There is also a post-rotation process in which a predetermined organizing operation (preparation operation) is executed after the image formation is completed. By separating the photosensitive drum from the developing roller, the recovery operation of the regulating blade 43 according to the present invention can be performed even during the period when the photosensitive drum 1 is rotating at each timing.

(Example 5)
FIG. 12 is a timing chart during the recovery operation of the regulating blade 43 in the present embodiment (the lower part of the figure shows the applied voltage value at the corresponding timing in the upper part of the figure).

  In the present embodiment, as in the fourth embodiment, a voltage having a positive polarity (a polarity opposite to the normal charging polarity of the toner of the present embodiment) is applied to the regulating blade 43 during standby for printing. This voltage is opposite in polarity to the voltage applied to the regulating blade 43 during image formation. Specifically, +300 V was applied to the regulating blade 43. As a result, a current in the direction opposite to that at the time of image formation flows through the regulating blade 43. At this time, the photosensitive drum 1 and the developing roller 41 are stopped, the photosensitive drum 1 and the developing roller 41 are separated from each other, and voltage application to the developing roller 41 is stopped.

  Also in this example, the same effect as in Example 1 could be obtained.

(Example 6)
FIG. 13 is a timing chart during the printing operation in the present embodiment (the lower part of the figure shows the applied voltage value at the corresponding timing in the upper part of the figure).

  In the present embodiment, a case where the same control as that in the first embodiment is employed using a long-life process cartridge (nominal life of 50000 sheets) will be described.

  Using a process cartridge with a nominal life of 50000 sheets, confirm whether there is any deterioration in fog in the latter half of the life when a low image ratio print is intermittently passed in an evaluation environment of 10.0 ° C. and 10% Rh. did. As a result, it was found that when a long-life process cartridge is used, the toner may fall before fogging deteriorates under the same control as in the first embodiment.

  This is considered to be caused by the fact that the process cartridge has a particularly long life, and the degree of aggregation of toner has increased in the latter half of the life. That is, in the configuration of the present embodiment, the toner holding force of the developing roller 41 decreases when the toner aggregation degree is 40% or more. At the same time, by applying a voltage to the developing roller 41 in a state where the application of the voltage to the regulating blade 43 is stopped, the toner is urged toward the regulating blade 43 and transferred to the regulating blade 43 side. As a result, it is considered that toner has accumulated on the downstream side of the nip portion between the developing roller 41 and the regulating blade 43, and as a result, the toner has dropped or scattered.

Here, a method for measuring the degree of toner aggregation will be described. A powder tester manufactured by Hosokawa Micron Corporation was used as the measuring device. First, three cylindrical sieves with a diameter of 100 mm are stacked, and in order from the top, 100 mesh (aperture 150 μm), 200 mesh (aperture 75 μm), 400 mesh (aperture 38 μm), and the distance to the mesh is 20 mm. Set as follows. 5.0 [g] of toner is placed on the uppermost 100 mesh screen, and the vibration table is vibrated for 15 seconds with an amplitude of 1 mm. After the vibration is stopped, the weight of the toner remaining on each sieve is measured. At this time, the amount of toner remaining on the 100 mesh screen is A [g], the amount of toner remaining on the 200 mesh screen is B [g], and the amount of toner remaining on the 400 mesh screen is C [g]. And the degree of aggregation expressed as a percentage is obtained from the following formula. The smaller the value of the degree of aggregation, the harder it is to aggregate.
a = (A / 5) × 100 (1)
b = (B / 5) × 100 × (3/5) (2)
c = (C / 5) × 100 × (1/5) (3)
Aggregation degree [%] = a + b + c (4)

  In this embodiment, the control as shown in FIG. That is, a predetermined voltage is applied to the developing roller 41 for a certain period of time (t7 to t8) after the application of the voltage to the regulating blade 43 is stopped (t7) after the developing roller 41 is stopped (t6). ). As a result, a current in the direction opposite to that during image formation flows through the regulating blade 43 (recovery operation).

  In this embodiment, after the application of the voltage to the developing roller 41 is stopped (t8), a predetermined voltage (the same polarity as that during image formation) is applied to the regulating blade 43 for a certain time (t9 to t9). t10). At this time, the voltage is applied only to the regulating blade 43, and a current flows from the developing roller 41 to the regulating blade 43. That is, the developing roller 41 has a high potential on the positive polarity (opposite polarity to the normal charging polarity of the toner of the present embodiment), and the regulating blade 43 has the negative polarity (normal charging polarity of the toner of the present embodiment). High potential. As a result, a current in the same direction as that during image formation flows through the regulating blade.

  Specifically, after the application of the voltage to the regulation blade 43 after the development roller 41 is stopped, −300 V is continuously applied to the development roller 41 for 2 seconds, and then the regulation blade 43 is applied. −500 V was applied for 0.5 seconds.

  In this embodiment, a current of +3.0 μA flows through the regulating blade 43 during image formation. When a voltage is applied only to the developing roller 41 after the developing roller 41 is stopped, a current of −1.0 μA flows through the regulating blade 43. Thereafter, when a voltage is applied only to the regulating blade 43, a current of +1.0 μA flows through the regulating blade 43.

  In order to confirm the effect of this example, the above-described experiment (2) was performed on this example.

  Table 4 shows the evaluation results of the experiment (2) in a process cartridge having a nominal life of 50,000 sheets and a long life. According to this embodiment, after the recovery operation of the regulation blade 43, a voltage is applied to the regulation blade 43 so that a current in the same direction as that during image formation flows again. As a result, the toner accumulated on the regulating blade 43 is urged toward the developing roller 41 and transferred again to the developing roller 41 side. As a result, toner can be prevented from dropping even in a long-life process cartridge. In addition, as in the above embodiments, fogging can be suppressed.

  In particular, as in this embodiment, after the recovery operation of the restriction blade 43, before the subsequent printing operation is performed (typically following the recovery operation), a current in the same direction as that during image formation is passed through the restriction blade 43. By performing the operation, the toner can be effectively prevented from dropping or scattering.

  Note that the applied voltage value, applied current value, and application time when a current in the same direction as that during image formation is passed through the regulating blade 43 also depends on the setting when a current in the reverse direction is passed. It can change suitably so that the effect of this may be acquired.

[Other Embodiments]
The present invention has been described with reference to a specific embodiment. However, the present invention is not limited to the above-described embodiment.

  For example, the applied voltage value, the applied current value, the application time, and the like when a current in the reverse direction flows through the regulating blade 43 may be changed according to the usage amount of the developing device 4 so as to obtain the desired effect. Good. In this case, for example, the image forming apparatus 100 stores a storage unit (counter) that stores the number of images formed using the developing device 4 as a detecting unit (use history detecting unit) that detects information correlated with the usage amount of the developing device 4. Etc. Then, based on the information, the CPU 111 as the control unit changes the applied voltage value, the applied current value, the applied time, and the like when a current in the reverse direction flows through the regulating blade 43 according to the usage amount of the developing device 4. Can be controlled. Typically, as the usage amount of the developing device 4 increases, the potential difference between the developing roller 41 and the regulating blade 43 when a current in the reverse direction is passed through the regulating blade 43 is increased and / or the current is reduced. Control the flow time to be longer. Here, the usage amount of the developing device 4 may be a total usage amount throughout the life of the developing device 4 or may be a usage amount for a predetermined unit such as for each printing operation. The detection unit may be provided in any of the apparatus main body 11, the developing apparatus 4, and the process cartridge 12 of the image forming apparatus 100.

  Further, the image forming apparatus may be an arbitrary image forming apparatus such as a printer, a copier, a facsimile machine, or a multifunction machine combining these functions. The image forming apparatus is a direct transfer type color image forming apparatus that uses a transfer material carrier and sequentially superimposes and transfers a plurality of color toner images onto the transfer material carried on the transfer material carrier. May be. Further, the image forming apparatus uses an intermediate transfer body, and an intermediate transfer type color image forming apparatus that subsequently transfers a multi-toner image obtained by superimposing and transferring a plurality of color toner images onto the intermediate transfer body onto a transfer material. It may be. By applying the present invention to the developing device included in these arbitrary image forming apparatuses, the same effects as described above can be obtained.

  Further, the cartridge that can be attached to and detached from the apparatus main body of the image forming apparatus is not limited to the process cartridge, and may be a developing cartridge in which the developing device is substantially detachable from the apparatus main body. .

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 4 Developing apparatus 12 Process cartridge 41 Developing roller 44 Regulation blade 51 Development power supply 52 Regulation power supply

Claims (14)

A rotatable developer carrier carrying a developer for developing an electrostatic image;
A developer regulating member that regulates the developer on the developer carrying member, the developer regulating member having a conductive portion formed of a resin or an elastomer containing an ionic conductive agent;
First voltage applying means for applying a voltage to the developer carrier;
Second voltage applying means for applying a voltage to the developer regulating member;
When the rotation of the developer carrier is stopped, the magnitude relationship between the value of the voltage applied to the developer carrier and the value of the voltage applied to the developer regulating member is An operation of applying a voltage opposite to that when the body rotates and performing the development from the first and second voltage application means to the developer carrier and the developer regulating member, respectively. Control means to be executed;
An image forming apparatus comprising:   2. The image forming apparatus according to claim 1, wherein a current in a direction opposite to that when the developer carrying member rotates and performs the development flows through the developer regulating member during the operation.   During the operation, the voltage within a range that does not cause a leak between the developer carrying member and the developer regulating member is applied from the first and second voltage applying means to the developer carrying member and the developer regulating member. The image forming apparatus according to claim 1, wherein each of the image forming apparatuses is applied to the image forming apparatus.   The image forming apparatus according to claim 1, wherein the control unit causes the operation to be executed following a printing operation.   The image forming apparatus according to claim 1, wherein the control unit causes the operation to be performed when waiting for a print signal to be input.   The control means, after the operation, in a state where the rotation of the developer carrier is stopped, the value of the voltage applied to the developer carrier and the value of the voltage applied to the developer regulating member Is applied to the developer carrier and the development from the first and second voltage application means so that the developer carrier is rotated and the development is carried out. The image forming apparatus according to claim 1, further performing an operation of applying each to the agent regulating member.   7. The developer carrier according to claim 1, wherein the developer carrier is separated from an image carrier that carries an electrostatic image supplied with a developer from the developer carrier. The image forming apparatus according to claim 1.   The developer regulating member includes the conductive portion and a support member that supports the conductive portion, and the conductive portion is in contact with the developer carrying member. The image forming apparatus according to claim 7.   9. The developer according to claim 1, wherein at least one of titanium oxide, aluminum oxide, zinc oxide, cerium oxide, tin oxide, and strontium titanate is externally added to the developer. Image forming apparatus.   The image forming apparatus according to claim 1, wherein the developer contains conductive carbon black or conductive magnetic particles. A rotatable developer carrying member for carrying a developer for developing an electrostatic image, and a developer regulating member for regulating the developer on the developer carrying member, wherein a resin containing an ionic conductive agent or A developer regulating member having a conductive portion formed of an elastomer, and a developer recovery member electrical resistance recovery method in a developing device having:
When the rotation of the developer carrier is stopped, the magnitude relationship between the value of the voltage applied to the developer carrier and the value of the voltage applied to the developer regulating member is The electrical resistance recovery of the developer regulating member is applied to the developer carrying body and the developer regulating member, respectively, such that a voltage that is opposite to that when the body rotates and performs the development is applied. Method.   12. The development according to claim 11, wherein when the voltage is applied, a current in a direction opposite to that when the developer carrying member rotates and the development is performed flows through the developer regulating member. Method for recovering electrical resistance of agent regulating member.   When applying the voltage, a voltage in a range that does not cause a leak between the developer carrying member and the developer regulating member is applied to the developer carrying member and the developer regulating member, respectively. The method for recovering electrical resistance of a developer regulating member according to claim 11 or 12.   The magnitude of the voltage applied to the developer carrying member and the voltage applied to the developer regulating member in a state where the rotation of the developer carrying member is stopped after the application of the voltage. 2. A voltage is applied to the developer carrier and the developer regulating member so that the relationship is the same as when the developer carrier rotates and performs the development. The method for recovering electrical resistance of the developer regulating member according to any one of claims 11 to 13.

Images