JP4564853B2 - Image forming apparatus and image forming method - Google Patents

Description

  The present invention relates to an image forming apparatus and an image forming method used for a printer, a fax machine, a copying machine, and the like.

  Conventionally, as a developing device for visualizing an electrostatic latent image using a one-component developer, a developer carrying body provided opposite to the electrostatic latent image carrying body is provided, and development is performed around the developer carrying body. A device including a developer regulating member and a developer supply member is known. In this developing apparatus, the one-component developer accommodated in the developing device is supplied to the developer carrying member while being appropriately frictionally charged by the rubbing between the developer carrying member and the developer supply member. The developer carried on the surface of the developer carrying member is regulated by a developer regulating member to be a uniform thin layer and given a desired charge. In the development area between the electrostatic latent image carrier and the developer carrier, the developer on the developer carrier is transferred to the electrostatic latent image on the electrostatic latent image carrier by the developing electric field, The electrostatic latent image is visualized as a toner image. The developer that is not used for development in the development region and remains on the developer carrier is scraped off from the developer carrier at the contact portion with the developer supply member. At the same time, a new developer is supplied onto the developer carrier by the rotation of the developer supply member. On the other hand, the developer scraped off by the developer supply member is mixed with the developer in the developing device by the rotation of the developer supply member. As the developer supply member, a developing device using a single foam is proposed (for example, Patent Document 1). This single-foam developer supply member has a substantial contact area with the developer-carrying member as compared with a conventional open-cell foam, so that the supply rate to the developer-carrying member is improved.

JP-A-8-160735

  However, in many of the developing apparatuses conventionally proposed including Patent Document 1, the functions of the developer supplying member and the triboelectric charging function of the developer supplying member are mentioned, but they are sufficiently necessary for scraping off the development residual toner. The condition is not specified. This is considered to be because, if the developer supply efficiency is improved, the scraping function of the development residual toner becomes rough. In the state where the toner that is not consumed by the development remains without being scraped off from the surface of the developer carrier, the toner remaining on the developer carrier and the toner that is supplied later are different if the toner consumption varies depending on the image. Charge amount will be different. For this reason, for example, if a halftone image is formed after forming a solid image, the development start voltage changes in a toner non-consumed portion, and a uniform halftone image cannot be formed.

  Further, generally used toner is obtained by a pulverization method or a polymerization method, and has a constitution in which a colorant, a release agent, a polarity control agent, etc. are dispersed in a base resin, but has a fluidity function. Therefore, the external additive is scattered on the surface of the base resin. However, when the toner that is not consumed by the development remains without being scraped off the surface of the developer carrier, the external additive is buried in the base resin due to friction with the developer supply member and the developer regulating member, and the fluidity Toner deterioration such as a decrease in toner and a change in toner charging characteristics is promoted. Further, due to the deterioration of the toner, so-called toner filming in which the toner adheres to the developer carrying member is likely to occur, and the charging performance on the surface of the developer carrying member cannot be maintained.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to reduce the deterioration of the toner by suppressing the remaining of the development residual toner on the developer carrying member, and thereby the developer carrying member. It is an object to provide an image forming apparatus and an image forming method capable of maintaining the surface charging performance.

In order to achieve the above object, the image forming apparatus according to claim 1 is a rotatable developer carrying member that is provided opposite to the image carrying member and carries and conveys the developer contained in the developing device. And a developer regulating member that regulates the amount of developer on the developer carrying member, and a rotatable developer supplying member that contacts the developer carrying member and supplies and scrapes the developer. In the image forming apparatus, a single-component developer having a cohesion degree in the range of 4 to 80% is used as the developer , and the developer carrier has a JIS-A hardness of 10 to 70 ° on a core metal. The developer supplying member has an elastic layer, and an elastic layer having a thickness of dmm made of a material having a JIS-A hardness of 10 to 30 ° is formed, and the developer supplying member bites into the developer carrying member. And the developer carrying body is Xmm <0 mm <Xmm <1.8 mm <dmm The ratio of the mutual surface is moved forward in abutment portion, the circumferential speed V _DR of the developer carrying member and the circumferential speed V _SP of the developer supplying member with the developer supplying member is | V _{SP /} V _DR | ≦ 0.5 or 1.5 ≦ | V _SP / V _DR | ≦ 4.
The image forming apparatus according to claim 2 is the image forming apparatus according to claim 1, wherein the ratio is 0.4 ≦ | V _SP / V _DR | ≦ 0.5 or 1.5. .
The image forming apparatus according to claim 3, a rotatable developer carrying member for carrying and conveying the developer contained in the developing device provided opposite to the latent image carrier, the developer bearing member In the image forming apparatus comprising: a developer regulating member that regulates the amount of the developer; and a rotatable developer supply member that contacts the developer carrying member and supplies and scrapes the developer. And the developer carrying member has an elastic layer having a JIS-A hardness of 10 to 70 ° on the core bar, and the developer carrying member has a cohesion degree of 4 to 80%. The developer supply member is formed with a flexible layer having a thickness of dmm made of a flexible material having a JIS-A hardness of 10 to 30 °, and the developer supply member bites into the developer carrier. The amount Xmm is 0 mm <Xmm <1.8 mm <dmm, and the developer carrier and the development Agent mutual surface contact portion between the supplying member is moved in the opposite direction, the ratio of the circumferential speed V _DR of the developer carrying member and the circumferential speed V _SP of the developer supply member is 0.8 ≦ | V _SP / V _DR | ≦ 3 .
An image forming apparatus according to a fourth aspect is the image forming apparatus according to the second aspect, wherein the ratio is 0.8 ≦ | V _SP / V _DR | ≦ 1.5.
An image forming apparatus according to a fifth aspect is the image forming apparatus according to the first or third aspect, wherein the elastic layer of the developer carrying member is made of a rubber material.
An image forming apparatus according to a sixth aspect is the image forming apparatus according to the first or third aspect, wherein the material of the developer supply member is polyurethane foam.
The image forming apparatus according to claim 7, in the image forming apparatus according to claim 1 or 3, further comprising: a developer moving member for transporting direction away the developer in the developing device from the developing agent supplying member It is a feature.
The image forming apparatus according to claim 8, in the image forming apparatus according to claim 1 or 3, the developer of the size of the developer carrying member 18 mm, the diameter of the developer supply member 16 mm, for the developer carrying member The amount of biting of the supply member is 1 mm, and the surfaces of the developer carrier and the developer supply member are moved in opposite directions at the contact portion between the developer carrier and the developer supply member. When the peripheral speed ratio | V _SP / V _DR | is continuously operated under a condition of 0.9, the wear amount of the developer carrying member is 0.5 μm / hr or more.
The image forming apparatus according to claim 9, in the image forming apparatus according to claim 1 or 3, in the developer, the ratio of the projected area to the area by the average diameter of the toner particles is the use of spherical toner is 90% or more It is a feature.
The image forming apparatus according to claim 10, in the image forming apparatus according to claim 1 or 3, the the developer carrying member and the developer regulating member and the developer supplying member, detachably mountable to an image forming apparatus main body It is characterized by being configured as a single integrated component.
The image forming method according to claim 11 , wherein the one-component developer contained in the developing device is supplied to the developer carrying member by the developer supplying member and scraped to develop the developer on the developer carrying member. The toner is regulated by a developer regulating member, and a developer is attached to the latent image on the image carrier by a developing electric field formed between the developer carrier and an image carrier on which a latent image has been previously formed. In the image forming method for forming an image, a one-component developer having a cohesion degree in the range of 4 to 80% is used for the developer , and the developer carrier has a JIS-A hardness of 10 to 70 on a core metal. The developer supplying member has an elastic layer having a thickness of dmm made of a material having a JIS-A hardness of 10 to 30 °, and the developer carrying member of the developer supplying member. The bite amount Xmm is 0 mm <Xmm <1.8 mm <dmm, The developer carrier and the developer supply member are rotated so that their surfaces move in the forward direction at the contact portion between the developer carrier and the developer supply member, and the peripheral speed _VDR of the developer carrier and the peripheral speed V of the developer supply member the ratio of the _{SP |} is characterized in that a _{≦ 4 | V SP / V DR} | ≦ 0.5 or _{1.5 ≦ | V SP / V DR} .
The image forming method of claim 12 is the image forming method of claim 11, wherein the ratio is 0.4 ≦ | V _SP / V _DR | ≦ 0.5 or 1.5. .
The image forming method according to claim 13, wherein the one-component developer contained in the developing device is supplied to the developer carrying member by the developer supplying member and scraped to develop the developer on the developer carrying member. The toner is regulated by a developer regulating member, and a developer is attached to the latent image on the image carrier by a developing electric field formed between the developer carrier and an image carrier on which a latent image has been previously formed. In the image forming method for forming an image, a one-component developer having a cohesion degree in the range of 4 to 80% is used for the developer , and the developer carrier has a JIS-A hardness of 10 to 10 on a cored bar. The developer supplying member has a flexible layer having a thickness of dmm made of a flexible material having a JIS-A hardness of 10 to 30 °. The feed member bites into the developer carrier Xmm is 0 mm <Xmm <1.8 m m <a dmm, the developer carrying member and the developer is rotated so that their surfaces at the contact portion between the supply member moves in the opposite direction, the developer carrying member of the peripheral speed V _DR and the developer The ratio of the supply member to the peripheral speed V _SP is 0.8 ≦ | V _SP / V _DR | ≦ 3.
An image forming method according to a fourteenth aspect is the image forming method according to the thirteenth aspect, characterized in that the ratio is 0.8 ≦ | V _SP / V _DR | ≦ 1.5.
The image forming method of 請 Motomeko 1 5, and characterized in that in the image forming method according to claim 11 or 13, to transfer a direction away from the developer supplying member by the developer moving member the developer within the developing device To do.
The image forming method of claim 16 is the image forming method of claim 11 or 13 , wherein the developer carrying member has a diameter of 18 mm, the developer supply member has a diameter of 16 mm, and the developer with respect to the developer carrying member. The amount of biting of the supply member is 1 mm, the surfaces of the developer carrier and the developer supply member are moved in opposite directions at the contact portion between the developer carrier and the developer phase supply member. When the peripheral speed ratio | V _SP / V _DR | is continuously operated under a condition of 0.9, a material having a wear amount of the developer carrier of 0.5 μm / hr or more is used for the developer carrier. An image forming method.
The image forming method according to claim 17 is the image forming method according to claim 11 or 13 , wherein a spherical toner having a ratio of a projected area to an area based on an average diameter of toner particles of 90% or more is used as the developer. It is a feature.
According to the image forming apparatus and the image forming method, when the developer supply member comes into contact with the developer carrier, the toner on the developer carrier is scraped off, and the toner is newly supplied onto the developer carrier. As a result, the toner on the developer carrier is replaced. At this time, since the peripheral speed ratio between the developer carrier and the developer supply member is set in the above range, the developer supply member has a high scraping rate, as is apparent from the experimental results described later, and the developer. Residual development residual toner is prevented from remaining on the carrier.

  According to the present invention, an image forming apparatus and an image forming apparatus capable of reducing the deterioration of the toner and maintaining the charging performance of the surface of the developer carrying body by suppressing the remaining of the development residual toner on the developer carrying body. There is an excellent effect that a method can be provided.

  A first embodiment when the present invention is applied to a printer which is an image forming apparatus will be described below. First, the overall schematic configuration and operation of the printer will be described. FIG. 1 is a configuration diagram showing an overall schematic configuration of a printer according to the present embodiment. This printer irradiates the photosensitive member 1 with a charging roller 2 that uniformly charges the surface of the photosensitive member 1 and a laser beam modulated based on image information around the drum-shaped photosensitive member 1 that is an image carrier. The exposure device 3, the developing device 4 that develops the electrostatic latent image formed on the photosensitive member 1 to form a toner image, and the transfer that transfers the toner image formed on the photosensitive member 1 onto a transfer paper P as a transfer material A belt 5, a cleaning device 6 for removing toner remaining on the photosensitive member 1 after transfer, and the like are sequentially disposed. Also, a registration roller pair 7 that feeds and conveys the transfer paper P between the photoconductor 1 and the transfer belt 5 from a paper feed tray or the like (not shown) and the toner on the transfer paper P. And a fixing device (not shown) for fixing the image.

  In the printer having the above configuration, the surface of the photosensitive member 1 rotating in the direction of the arrow a is uniformly charged to a predetermined positive or negative charging potential by the charging roller 2, and then a laser beam modulated based on image information is exposed. Scanned and irradiated in the body axis direction. Thereby, an electrostatic latent image is formed on the photoreceptor 1. The electrostatic latent image formed on the photoconductor 1 is developed into a toner image by attaching toner charged by the developing device 4 in the developing region. On the other hand, the transfer paper P is fed / conveyed by a paper feeding / conveying device (not shown), and is sent / conveyed to a transfer portion where the photosensitive member 1 and the transfer belt 5 face each other at a predetermined timing by a pair of registration rollers 7. Then, the transfer belt 5 applies a charge having a polarity opposite to that of the toner image on the photoconductor 1 to the transfer paper 20, whereby the toner image formed on the photoconductor 1 is transferred to the transfer paper P. Next, the transfer paper P is separated from the photoreceptor 1 and sent to a fixing device (not shown). After the toner image is fixed by the fixing device, the transfer paper P is discharged out of the device. The surface of the photoconductor 1 after the toner image is transferred by the transfer belt 5 is cleaned by the cleaning blade 61 of the cleaning device 6, and the toner remaining on the photoconductor 1 is removed.

  FIG. 2 is a configuration diagram showing the configuration of the developing device. As shown in FIG. 2, the developing device 4 includes a developing roller 41 as a developer carrying member that exposes a part of the peripheral surface from the opening of the developing device 40 and faces the photosensitive member 1, and a developer supply member. Supply roller 42 and a regulating blade 43 as a developer regulating member. The developing device 40 includes an agitator 44 as a developer transfer member.

  In the developing device 4, the developer accommodated in the developing device 40 is mechanically supplied and carried on the surface of the supply roller 42 while being stirred by the agitator 44. The supply roller 42 conveys the toner to a portion facing the developing roller 41 while carrying the toner, and supplies the toner while sliding to the developing roller 41 while appropriately frictionally charging. The toner supplied to the developing roller 41 is thinned to an appropriate layer thickness by a regulating blade 43 that is in contact with the developing roller 41 via the toner. At the same time, the toner supplied to the developing roller 41 is rubbed between the developing roller 41 and the regulating blade 43 surface by being sandwiched between the developing roller 41 and the regulating blade 43, and is frictionally charged to a desired polarity. Then, the developing roller 41 is conveyed to a developing region which is a portion facing the photosensitive member 1 by rotation in the arrow direction. In the developing area, the toner layer on the developing roller 41 is transferred to the electrostatic latent image on the photoreceptor 1 by a developing electric field, and the electrostatic latent image is visualized as a toner image. The toner layer that is not used for development in the development area and remains on the development roller 41 is scraped off from the development roller 41 at a contact portion with the supply roller 42. At the same time, the developer is newly supplied onto the developing roller 41 by the rotation of the supply roller 42. On the other hand, the developer scraped off by the supply roller 42 is returned to the developing device 40 by the rotation of the supply roller 42, and transferred in a direction away from the supply roller 42 by the rotation of the agitator 44, and stirred in the developing device 40. Mixed.

  As shown in FIG. 2, the regulation blade 43 is a so-called belly contact where the tip is directed downstream with respect to the rotation direction of the developing roller 41 and the central portion of the regulation blade 43 abuts. The contact method of the regulating blade 43 is not limited to this, and it can be performed in the reverse direction or by edge contact. The material of the regulating blade 43 is a relatively hard material such as a metal such as SUS304 having a thickness of 0.1 to 0.15 [mm], a rubber material such as polyurethane rubber having a thickness of 1 to 2 [mm], or a silicone resin. High resin materials can be used. Since the resistance can be reduced by mixing carbon black or the like other than metal, an electric field can be formed between the developing roller 41 by connecting a bias power source.

The restriction blade 43 is preferably 10 to 15 [mm] as a free end length from the holder. If the upper limit is exceeded, the developing device 4 becomes large and cannot be compactly accommodated. If the lower limit is exceeded, vibration tends to occur when contacting the surface of the developing roller 41, and abnormal images such as unevenness in the horizontal direction are formed on the image. It tends to occur. The contact pressure is in the range of 0.049 to 2.45 [N / cm] (5 to 250 [gf / cm]). If the upper limit is exceeded, the toner adhesion amount on the developing roller 41 decreases and the toner charge amount increases too much, so the development amount decreases and the image density decreases. If the lower limit is not reached, a thin layer may not be formed uniformly, and the toner mass may pass through the regulating blade 43, resulting in a significant reduction in image quality. Further, the contact angle of the regulating blade 43 is preferably 10 to 45 ° with respect to the tangent line of the developing roller 41 in the direction in which the tip faces the downstream side of the developing roller 41. A portion unnecessary for forming a toner thin layer sandwiched between the regulating blade 43 and the developing roller 41 is peeled off from the developing roller 41, and is 0.4 to 0.8 [mg / cm per unit area as a target range. ² ] with a uniform thickness. The toner charging at this time is finally in the range of -10 to -30 [μC / g]. In the present embodiment, a SUS plate having a thickness of 0.1 mm is used as the regulating blade 43, and the contact pressure is set to 60 [gf / cm]. At this time, a target toner adhesion amount could be obtained on the developing roller.

  The supply roller 42 is made of a flexible material, such as foamed polyurethane, and has a structure that can easily hold the toner with a cell having a diameter of 50 to 500 μm. Further, the hardness of the supply roller is relatively low, 10 to 30 ° (JIS-A), and can be brought into contact with the developing roller 41 uniformly.

Next, the linear speed ratio between the developing roller and the supply roller, which is a feature of the present invention, will be described. In the first embodiment, the supply roller 42 is driven to rotate in the direction opposite to the developing roller 41, that is, the surface of the supply roller 42 is moved in the forward direction at the contact portion of both the rollers 41 and 42. The toner of a predetermined polarity existing on the supply roller 42 (or inside the supply roller 42) is sandwiched between the rollers 41 and 42 whose surfaces rotate in the forward direction at the contact portions of the rollers 41 and 42. A charged charge is obtained by the frictional charging effect. The toner on the supply roller 42 is held on the developing roller 41 by the electrostatic force due to the frictional charging effect and the conveying effect due to the surface roughness of the developing roller 41. However, the toner layer on the developing roller 41 at this time is not uniform and is considerably excessively attached (1 to 3 [mg / cm ² ]). Therefore, in this embodiment, when the linear velocity of the developing roller 41 is V _DR and the linear velocity of the supply roller 42 is V _SP , the linear velocity ratio of both rollers 41 and 42 is | V _SP / V _DR | ≦ 0. .5 or 1.5 ≦ | V _SP / V _DR | ≦ 4.

FIG. 3 is a characteristic diagram showing the relationship between the scraping rate and the linear velocity ratio between the developing roller and the supply roller. The definition of the scraping rate is how much mutual movement occurs in one contact when a supply roller carrying one color toner contacts a developing roller carrying another color toner, and the distribution of chromaticity By looking at, it is possible to calculate the initial toner amount and the respective toner amounts after contact. As shown in FIG. 3, when a new toner (shown as New in the figure) is used, the scraping rate is less than 70% in the critical portion where the linear speed ratio is 0.6 and 1.2. When using old toner (denoted by Old in the figure) whose agglomeration rate is 80% due to deterioration, the scraping rate is less than 70% in the critical portion where the linear speed ratio is 0.5 and 1.5. . From the above results, in order to obtain a scraping rate of 70% or more, the linear velocity ratio between the developing roller 41 and the supply roller 42 is set to | V _SP / V _DR | ≦ 0.5 or | V _SP / V _DR | ≧ It can be seen that a range of 1.5 is preferable. When the scraping rate is less than 70%, the toner deteriorates, the toner charging characteristics change over time, or toner filming occurs, and the image quality is lowered. On the other hand, if the linear velocity ratio | V _SP / V _DR | between the developing roller 41 and the supply roller 42 exceeds 4, the difference in linear velocity between the developing roller 41 and the supply roller becomes excessive, and frictional heat is generated at the contact portion. End up. For this reason, the toner present in the vicinity of the contact portion is likely to melt, and filming on the rollers 41 and 42 is likely to occur, which is not preferable.

Next, a second embodiment will be described. FIG. 4 is a configuration diagram showing the configuration of the developing device according to the second embodiment. Note that, in the developing device according to the second embodiment, since the direction other than the rotation direction of the supply roller is the same, the same reference numerals are given and description thereof is omitted. As shown in FIG. 4, in the second embodiment, the supply roller 42 rotates in the forward direction with respect to the developing roller 41, that is, the surfaces of the supply roller 42 move in opposite directions at the contact portion of both the rollers 41 and 42. It is rotationally driven. The toner of a predetermined polarity existing on the supply roller 42 (or inside the supply roller 42) is sandwiched between the rollers 41 and 42 that rotate in opposite directions at the contact point of the rollers 41 and 42, thereby causing a triboelectric charging effect. To obtain a charged charge. The toner on the supply roller 42 is held on the developing roller 41 by the electrostatic force due to the frictional charging effect and the conveying effect due to the surface roughness of the developing roller 41. However, the toner layer on the developing roller 41 at this time is not uniform and is considerably excessively attached (1 to 3 [mg / cm ² ]). Therefore, in this embodiment, the linear velocity of the developing roller 41 and _{V DR,} when the linear velocity of the feed roller 42 and _{V SP,} a 41-wire speed ratio of the rollers 0.8 ≦ _{| V} DR / _{V SP} | ≦ 3.

FIG. 5 is a characteristic diagram showing a scraping rate with respect to a linear speed ratio between the developing roller and the supply roller. As shown in FIG. 5, when a new toner (shown as New in the figure) is used, the scraping rate is less than 70% when the linear speed ratio falls below a critical portion of 0.7. In the case of using old toner (denoted by Old in the figure) that has deteriorated to an aggregation rate of 80%, the scraping rate is less than 70% when the linear speed ratio falls below the critical part of 0.8. From the above results, it can be seen that in order to obtain a scraping rate of 70% or more, it is preferable that the linear velocity ratio of both rollers is in a range of | V _DR / V _SP | ≧ 0.8. When the scraping rate is less than 70%, the toner deteriorates, the toner charging characteristics change over time, or toner filming occurs, and the image quality is lowered. On the other hand, if the linear velocity ratio | V _SP / V _DR | between the developing roller 41 and the supply roller 42 exceeds 3, the linear velocity difference between the developing roller 41 and the supply roller becomes excessive, and frictional heat is generated at the contact portion. End up. For this reason, the toner present in the vicinity of the contact portion is likely to melt, and filming on the rollers 41 and 42 is likely to occur, which is not preferable.

  In the first and second embodiments, it is preferable to set the amount of biting of the supply roller 42 with respect to the developing roller 41 as follows. FIG. 6 is an explanatory diagram for explaining the amount of feed roller biting into the developing roller. As shown in FIG. 6, when the developing roller diameter is R1, the supply member diameter is R2, the thickness of the inner elastic member of the supply roller is d2, and the biting amount is X, 0 <X <1.8 <d2. It is preferable to satisfy the relationship. By adjusting the bite amount X, the scraping rate can be further improved. In this embodiment, a uniform image is obtained with R1 = R2 = 16 mm, d2 = 2 mm, and X = 1.2 mm. However, when the biting amount X exceeds 1.8 mm, the pitch of the elastic body appears on the developing roller. The supply becomes uneven. It should be noted that the amount of biting of the supply roller 42 with respect to the developing roller 41 depends on the toner charging characteristics and supply capability, and therefore it is necessary to set the optimum condition within the above range. Further, since the amount of the supply roller 42 that bites into the developing roller 41 ultimately depends on the characteristics of the motor and gear head that drives the development, it is necessary to consider all the drive systems. is there. In this embodiment, when the unit effective width is 240 mm (A4 length), the required torque is 14.7 to 24.5 N · cm (1.5 to 2.5 [kgf · cm]).

  As shown in FIGS. 2 and 4, an agitator 44, which is a developer transfer member that transfers the developer in the developer 40 in a direction away from the supply roller 42, may be disposed in the developer 40. The frequency of the toner in the developing device 40 passing through the supply nip portion between the developing roller 41 and the supply roller 42 and the regulating nip portion between the developing roller 41 and the regulating blade 43 is reduced by the rotation of the agitator 44. As a result, toner deterioration due to friction at the supply nip portion and the regulation nip portion is reduced, and the life is extended.

  Next, the configuration of the developing roller used in the first and second embodiments will be described. The photoreceptor 1 used in the present embodiment uses a rigid drum based on an aluminum tube. Therefore, it is preferable that the developing roller 41 used in this embodiment has a configuration in which an elastic layer is formed on a cored bar. A rubber material having a hardness (JIS-A) of 10 to 70 ° is preferably used for the elastic layer of the developing roller 41. The diameter of the developing roller 41 is preferably 10 to 30 mm. The surface of the developing roller 41 was appropriately changed to have a surface roughness Rz (10-point average roughness) of 1 to 4 μm. The range of the surface roughness Rz is 13 to 80% with respect to the volume average particle diameter of the toner, and is a range in which the toner is conveyed without being buried in the surface of the developing roller 41. Here, examples of materials that can be used as the rubber material of the developing roller 41 include silicon, butadiene, NBR, hydrin, and EPDM. In this embodiment, the developing roller 41 having a hardness (JIS-A) of 30 ° and a diameter of 16 mm is used.

Further, the surface layer of the developing roller 41 may be coated with a resin. The material for coating the surface layer of the developing roller 41 preferably has a charging polarity opposite to that of the toner. Examples of the material to be used include resins and rubber materials containing silicon, acrylic, polyurethane and the like. In order to obtain conductivity, a conductive material such as carbon black may be appropriately contained. In order to coat the developing roller 41 more uniformly, another resin may be mixed. Regarding the electrical resistance, the volume resistivity of the bulk including the coat layer is set, and the resistance and adjustment of the base layer are performed so that it can be set to 10 ³ to 10 ⁸ Ω · cm.

Further, the developing roller 41 may have a single layer structure, depending on the material. Although the developing roller 41 is scraped over time, toner and other things may adhere to the surface and so-called toner filming may occur on the surface. The cause is largely due to an increase in the adhesion between the toner and the surface of the developing roller 41. However, a decrease in fluidity due to the buried toner additive is also a major factor. Therefore, the developing roller 41 may be actively worn using a material that easily wears the developing roller 41. The developing ability can be stabilized by configuring the developing roller 41 to have the same volume resistivity regardless of the thickness. As a material, a conductive material such as carbon black is dispersed in a rubber material such as silicon, butadiene, NBR, hydrin, and EPDM, but the resistance is not changed no matter how much it is scraped. The development characteristics can be stabilized by improving the uniformity. Specifically, as the material used for the developing roller 41, the diameter of the developing roller 41 is 18 mm, the diameter of the supply roller 42 is 16 mm, and the amount of biting of the supply roller 42 with respect to the developing roller 41 is 1 mm. When the respective surfaces move in the opposite directions at the contact portion with the roller 42 and the peripheral speed ratio | V _SP / V _DR | between the developing roller 41 and the supply roller 42 is 0.9, It is preferable to use a developing roller having an abrasion amount of 0.5 [μm / hr] or more. If the amount of wear is less than [μm / hr], there is no problem as long as the conventional body surface energy material (silicon resin, fluorine resin, etc.) is coated, but with normal rubber materials (butadiene, hydrin, etc.) Those having an affinity for the developer are not preferable because the developer tends to adhere to the film and filming is likely to occur over time.

  Next, the toner used in this embodiment will be described. The toner is made by mixing a charge control agent (CCA) and a colorant with a base resin such as polyester, polyol, styrene acrylic, etc., and flows by adding external additives such as silica and titanium oxide around the toner. Increases sex. The particle size of the additive is usually in the range of 0.1 to 1.5 μm. Examples of the colorant include carbon black, phthalocyanine blue, quinacridone, and carmine. As the toner, a toner obtained by externally adding the above-mentioned types of additives to a base toner in which wax or the like is dispersed and mixed may be used. The volume average particle diameter of the toner is preferably in the range of 3 to 12 μm. The toner used in this embodiment is externally added with polyester as a main resin and silica and titanium as additives. Further, the volume average particle diameter of the toner is 6 μm, and it can sufficiently cope with a high resolution image of 1200 dpi or more.

  In addition, a toner whose aggregation degree changes in the range of 4 to 80% is used. A toner having a toner aggregation degree of less than 4% has extremely high fluidity. However, in practice, it is necessary to add a very large amount of an additive to the toner base. Therefore, the coverage of the toner base material with the additive becomes abnormally high, and at the same time, an additive that has not been able to adhere to the surface of the toner base body is present in the toner. Since the additive has a very high hardness with respect to the resin as typified by silica, it is not preferable because it damages members such as the developing roller 41 and the photoreceptor 1 and promotes member deterioration.

The toner aggregation degree is measured according to the toner aggregation degree measuring method and definition described in JP-A-7-160033. This toner cohesion degree is measured by using a first combination of sieve openings of 150 μm (upper), 75 μm (middle), and 45 μm (lower), and sieve openings of 75 μm (upper) and 45 μm (upper). The middle set) and the second set of 22 μm (lower) combination are used. Then, 2 grams of toner is placed on the upper sieve, the amplitude is 1 mm, and T = 20 + | (1.6−W) /0.016 | [sec] (W is the dynamic apparent specific gravity of the toner, and W = (P−a) c / 100 + a calculated by the following formula, P: firm apparent specific gravity, a: loose apparent specific gravity, c: degree of compression obtained from the ratio of loose apparent specific gravity to solid apparent specific gravity) Then, the weight of the toner remaining on each sieve is measured and calculated by the following formula.
(1) | (weight of toner remaining in the upper stage) / 2 | × 100
(2) | (weight of toner remaining in the middle stage) / 2 | × 100 × (3/5)
(3) | (weight of toner remaining in the lower stage) / 2 | × 100 × (1/5)
The total of the above three calculated values is defined as the degree of toner aggregation.

In addition, as the toner used in the exemplary embodiment, it is preferable to use a spherical toner having a projected area ratio of 90% or more with respect to an area based on an average diameter of toner particles. In a normal pulverized toner, this ratio is smaller than 90%. Spherical toner having this ratio of 90% or more is less likely to adhere to the developing roller, and the occurrence of filming and the like can be suppressed. Moreover, since there are few protrusions and it is easy to rotate, the toner deterioration by stirring can be suppressed. Therefore, toner does not aggregate over time, and filming of the developing roller due to the aggregated toner can be suppressed.
These toners are often produced by a polymerization method (emulsification, suspension, dispersion) or the like. It is also possible to make the toner diameter uniform. In this embodiment, the toner produced by the polymerization method has an average particle diameter of 6 μm and a ratio of 96%.

  Note that some of the plurality of devices constituting the printer may be configured as a process cartridge that is configured to be detachable integrally with the printer main body. FIG. 7 is a schematic diagram showing a configuration around the photoconductor. As shown in FIG. 7, the developing device 4 is a process in which a developing roller 41, a supply roller 42, a regulating blade 43, and an agitator 44 housed in a developing device 40 are integrated components that can be attached to and detached from the printer body. The cartridge 45 may be configured. If the parts such as the developing device 40, the developing roller 41, the supply roller 42, and the regulating blade 43 can be exchanged into a cartridge type, uniform development characteristics can be maintained constantly without being affected by toner deterioration. An image can be obtained. Further, the photosensitive member 1, the charging device 2, the developing device 4, and the cleaning device 6 may be configured as a process cartridge that is an integral structure that can be attached to and detached from the printer main body.

As described above, according to the first and second embodiments, the developing residual toner on the developing roller 41 as the developer carrying member is scraped off by the supply roller 42 as the developer supplying member and Toner is newly supplied and the toner on the developing roller 41 is replaced. At this time, since the linear speed ratio between the developing roller and the supply roller is defined within the above range, the scraping rate by the supply roller 42 is high, and the development residual toner is prevented from remaining on the developing roller 41. Therefore, the deterioration of the toner is reduced, and the charging performance of the developing roller surface can be maintained.
In addition, according to the embodiment, the scraping rate by the supply roller 42 can be further improved by defining the amount of biting of the supply roller 42 into the developing roller 41 within the above range.
Further, according to the present embodiment, since the agitator 44 that is a developer transfer member is provided, the supply nip portion between the developing roller 41 and the supply roller 42 and the restriction between the developing roller 41 and the restriction blade 43 are provided. The number of passes through the nip is reduced. Therefore, the progress of the toner additive burying is suppressed, and the deterioration of the toner is suppressed.
Further, according to this embodiment, since the developing roller 41 is made of a material that easily wears, the toner hardly adheres to the surface of the developing roller 41, and the surface of the developing roller 41 can be maintained at the initial charging performance.
Further, according to the present embodiment, since spherical toner is used, it is difficult to adhere to the developing roller 41, and toner deterioration due to stirring is suppressed.
In addition, according to the present embodiment, by configuring the developing device 4 as a process cartridge that can be attached to and detached from the apparatus main body, a uniform image can be obtained without being affected by toner deterioration.

  FIG. 8 is a configuration diagram of a developing device according to another embodiment. The developing device shown in FIG. 8 includes a developing roller 52 as a developer carrying member that exposes a part of the peripheral surface from the opening of the developing container 50 and faces the photosensitive belt 51. A regulation roller 53 as a developer regulation member, a supply roller 54 as a developer supply member, and agitators 55, 56, and 57 as developer transfer members are provided. In the first and second embodiments, the regulating blade 43 is used as the regulating member. However, as shown in FIG. 8, a thin layer may be formed by contacting a cylindrical regulating roller 53. In the first and second embodiments, one agitator 44 is used as the developer transfer member, but a plurality of agitators 55, 56, and 57 may be provided as shown in FIG. In the first and second embodiments, the developing roller 41 having an elastic layer is used. However, as shown in FIG. 8, when a so-called photosensitive belt is used, the developing roller 41 has a high hardness. Since there is no problem, a metal roller or the like can be used.

  In the above-described embodiment, the image forming apparatus that directly transfers the toner image formed on the photoconductor onto the transfer paper has been described. However, the present invention is not limited to this. For example, the present invention can also be applied to an image forming apparatus that once transfers a toner image on a photosensitive member to an intermediate transfer member and then transfers the toner image on the intermediate transfer member to a transfer sheet. In the above embodiment, a monochrome image forming apparatus having one photoconductor 1 and one developing device 4 has been described as an example. However, the present invention is not limited to this. For example, the present invention can also be applied to a color image forming apparatus that sequentially forms toner images for each color on one photoconductor and sequentially transfers the respective color toner images on the photoconductor on an intermediate transfer body or transfer paper. . Further, for example, a plurality of image forming units including photoconductors are arranged side by side, toner images of different colors are formed on the photoconductors of the image forming units, and the toner images on the photoconductors are transferred to an intermediate transfer body or transfer paper. The present invention can also be applied to a tandem color image forming apparatus that superimposes and transfers the image.

1 is a configuration diagram showing an overall schematic configuration of a printer according to an embodiment. 1 is a configuration diagram showing a configuration of a developing device according to a first embodiment. The characteristic view which shows the scraping rate with respect to the linear velocity ratio of the developing roller and supply roller in the developing device. FIG. 6 is a configuration diagram illustrating a configuration of a developing device according to a second embodiment. The characteristic view which shows the scraping rate with respect to the linear velocity ratio of the developing roller and supply roller in the developing device. Explanatory drawing explaining the biting amount of the supply roller with respect to a developing roller. FIG. 3 is a schematic diagram showing a configuration around a photoconductor. FIG. 6 is a configuration diagram showing a configuration of a developing device according to another embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 4 Developing apparatus 40 Developing device 41 Developing roller 42 Supply roller 44 Agitator

Claims (17)

A rotatable developer carrier that is provided opposite to the image carrier and that carries and conveys the developer contained in the developing device, and a developer that regulates the amount of developer on the developer carrier In an image forming apparatus comprising a regulating member and a rotatable developer supply member that contacts the developer carrying member and supplies and scrapes the developer.
A one-component developer having a cohesion degree in the range of 4 to 80% is used as the developer.
The developer carrier has an elastic layer having a JIS-A hardness of 10 to 70 ° on a cored bar,
The developer supply member is formed with an elastic layer having a thickness of dmm made of a material having a JIS-A hardness of 10 to 30 °.
The amount Xmm of biting into the developer carrier of the developer supply member is 0 mm <Xmm <1.8 mm <dmm,
The ratio of the mutual surface is moved forward in abutment portion, the circumferential speed V _DR of the developer carrying member and the circumferential speed V _SP of the developer supplying member with the developer carrying member and the developer supplying member Is an image forming apparatus, wherein | V _SP / V _DR | ≦ 0.5 or 1.5 ≦ | V _SP / V _DR | ≦ 4.   The image forming apparatus according to claim 1.
  The above ratio is 0.4 ≦ | V _SP / V _DR An image forming apparatus characterized by satisfying | ≦ 0.5 or 1.5. A rotatable developer carrying member that is provided opposite to the latent image carrying member and carries and conveys the developer contained in the developing device, and a developer that regulates the amount of developer on the developer carrying member In an image forming apparatus comprising a regulating member and a rotatable developer supply member that contacts the developer carrying member and supplies and scrapes the developer.
A one-component developer having a cohesion degree in the range of 4 to 80% is used as the developer.
The developer carrier has an elastic layer having a JIS-A hardness of 10 to 70 ° on a cored bar,
The developer supplying member is formed with a flexible layer having a JIS-A hardness of 10 to 30 ° and a thickness of dmm made of a flexible material.
The amount Xmm of biting into the developer carrier of the developer supply member is 0 mm <Xmm <1.8 mm <dmm,
The ratio of the mutual surface move in opposite directions at the contact portion, and the circumferential speed V _DR of the developer carrying member and the circumferential speed V _SP of the developer supplying member with the developer carrying member and the developer supplying member Is an image forming apparatus, wherein 0.8 ≦ | V _SP / V _DR | ≦ 3.   The image forming apparatus according to claim 2.
  The above ratio is 0.8 ≦ | V _SP / V _DR An image forming apparatus characterized by satisfying | ≦ 1.5.   The image forming apparatus according to claim 1 or 3,
  An image forming apparatus, wherein the elastic layer of the developer carrying member is made of a rubber material.   The image forming apparatus according to claim 1 or 3,
  An image forming apparatus, wherein the material of the developer supply member is foamed polyurethane. The image forming apparatus according to claim 1 or 3,
An image forming apparatus comprising: a developer moving member for transferring the developer in the developing device in a direction away from the developer supply member. The image forming apparatus according to claim 1 or 3,
The developer carrying member has a diameter of 18 mm, the developer supplying member has a diameter of 16 mm, and the developer carrying member has a biting amount of 1 mm. The developer carrying member and the developer supplying member The surface of each other moves in the opposite direction at the abutting portion, and continuously operates under the condition that the peripheral speed ratio | V _SP / V _DR | of the developer carrying member and the development phase supply member becomes 0.9. In this case, the developer carrying member has an abrasion amount of 0.5 μm / hr or more. The image forming apparatus according to claim 1 or 3,
An image forming apparatus comprising: a spherical toner having a projected area ratio of 90% or more to an average toner particle diameter area as the developer. The image forming apparatus according to claim 1 or 3,
The image forming apparatus, wherein the developer carrying member, the developer regulating member, and the developer supplying member are configured as an integral component that is detachable from the image forming apparatus main body. The one-component developer accommodated in the developing device is supplied and scraped to the developer carrying member by the developer supplying member, and the developer on the developer carrying member is regulated by the developer regulating member, and the development is performed. In an image forming method of forming a toner image by attaching a developer to a latent image on an image carrier by a developing electric field formed between the agent carrier and an image carrier on which a latent image is formed in advance.
A one-component developer having a cohesion degree in the range of 4 to 80% is used as the developer.
The developer carrier has an elastic layer having a JIS-A hardness of 10 to 70 ° on a cored bar,
The developer supply member is formed with an elastic layer having a thickness of dmm made of a material having a JIS-A hardness of 10 to 30 °.
The amount Xmm of biting into the developer carrier of the developer supply member is 0 mm <Xmm <1.8 mm <dmm,
The developer carrier and the developer supply member are rotated so that their surfaces move in the forward direction at the contact portion between the developer carrier and the developer supply member, and the peripheral speed _VDR of the developer carrier and the peripheral speed V of the developer supply member the ratio of the _{SP | V SP / V DR |} ≦ 0.5 or _{1.5 ≦ | V SP / V DR} | ≦ 4 and image forming method characterized by.   The image forming method according to claim 11.
  The above ratio is 0.4 ≦ | V _SP / V _DR An image forming method characterized by satisfying | ≦ 0.5 or 1.5. The one-component developer accommodated in the developing device is supplied and scraped to the developer carrying member by the developer supplying member, and the developer on the developer carrying member is regulated by the developer regulating member, and the development is performed. In an image forming method of forming a toner image by attaching a developer to a latent image on an image carrier by a developing electric field formed between the agent carrier and an image carrier on which a latent image is formed in advance.
A one-component developer having a cohesion degree in the range of 4 to 80% is used as the developer.
The developer carrier has an elastic layer having a JIS-A hardness of 10 to 70 ° on a cored bar,
The developer supplying member is formed with a flexible layer having a JIS-A hardness of 10 to 30 ° and a thickness of dmm made of a flexible material.
The amount Xmm of biting into the developer carrier of the developer supply member is 0 mm <Xmm <1.8 mm <dmm,
The developer carrier and the developer supply member are rotated so that their surfaces move in opposite directions at the contact portion between the developer carrier and the developer supply member, and the peripheral speed _VDR of the developer carrier and the peripheral speed V of the developer supply member An image forming method, wherein a ratio to _SP is 0.8 ≦ | V _SP / V _DR | ≦ 3.   The image forming method according to claim 13.
  The above ratio is 0.8 ≦ | V _SP / V _DR An image forming method, wherein | ≦ 1.5. The image forming method 請 Motomeko 11 or 13,
An image forming method, wherein the developer in the developing device is transferred in a direction away from the developer supply member by a developer moving member. The image forming method according to claim 11 or 13 ,
The developer carrying member has a diameter of 18 mm, the developer supplying member has a diameter of 16 mm, and the developer carrying member has a biting amount of 1 mm. The developer carrying member and the developer supplying member The surface of each other moves in the opposite direction at the abutting portion, and continuously operates under the condition that the peripheral speed ratio | V _SP / V _DR | of the developer carrying member and the development phase supply member becomes 0.9. An image forming method characterized in that a material having an abrasion amount of 0.5 μm / hr or more is used for the developer carrying member. The image forming method according to claim 11 or 13 ,
An image forming method comprising using, as the developer, a spherical toner having a ratio of a projected area to an area based on an average diameter of toner particles of 90% or more.

Images