JP5834886B2 - Developing device, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device and a process cartridge used in an electrophotographic image forming apparatus, and an image forming apparatus including the developing device.

In an electrophotographic image forming apparatus such as a copying machine, a FAX, a printer, or a multifunction machine having a plurality of these functions, an image is formed using a developer provided in the developing device. As the developer, there is a one-component developer composed of a single toner, and the one-component developer includes a magnetic one-component developer and a non-magnetic one-component developer. In particular, in a developing apparatus using a non-magnetic one-component developer, it is required to maintain the chargeability of the developer in order to maintain stable quality for a long period of time. In particular, in order to achieve low-temperature fixing, it is required to use a low Tg (developer particle glass transition temperature) developer, and a low-stress developing device is required. In a low-stress developing device, when the developer is deteriorated, sufficient charge cannot be applied to the developer. Therefore, there are problems such as a solid follow-up failure and a background stain in which toner is consumed even in a white paper portion.
Therefore, as a technique for increasing the chargeability of the developer, Patent Document 1 describes a reserve for a supply member that supplies toner to a developer carrying body that carries and transports toner for the purpose of maintaining the charge of the toner that becomes the developer. The charging member is brought into contact, and at the contact nip portion between the preliminary charging member and the supply member, a speed difference (for example, a speed difference of 0) is smaller than the supply member peripheral surface in the same direction as the supply member peripheral surface and smaller than the supply member peripheral speed. ) Is disclosed.

  In general, in a developing device using a one-component developer, the developer is charged only when it passes between the developer carrier and the regulating member pressed against the developer carrier. There are few opportunities for the agent to be charged, and particularly after a long period of use, the developer is insufficiently charged, which causes problems such as poor solid tracking and smearing where toner is consumed even in white paper. In Patent Document 1, since the preliminary charging member is brought into contact with the supply member, the current charging shortage of the agent can be compensated. However, since the preliminary charging member has been in contact since the new state, the developer is excessive when it is new. There is a new problem that an abnormal image such as an afterimage is generated by applying a large amount of charge. SUMMARY OF THE INVENTION An object of the present invention is to provide a developing device and an image forming apparatus that can maintain the chargeability of a one-component developer for a long period of time, have less solid follow-up failure and background contamination, and can suppress the occurrence of abnormal images such as afterimages. To do.

  A developing device according to the present invention includes a developer carrier, a supply member that supplies developer to the developer carrier, a regulating member that regulates the amount of developer on the developer carrier, and a developer storage. , A developer storage chamber whose volume changes according to the amount of developer stored, and a contact member movable according to the volume change of the developer storage chamber, the contact member of the developer storage chamber It is characterized by contacting the supply member after the volume change.

  According to the present invention, when the developer is in a new state, the developer conveyed by the supply member is conveyed onto the developer carrier, and is frictionally charged between the developer carrier and the regulating member, so that the appropriate charge The quantity can be obtained. In addition, when the developer is in a deteriorated state and the remaining amount of the developer is reduced, and the volume of the developer storage chamber changes, the contact member comes into contact with the supply member, so that the developer is placed between the supply member and the contact member. The developer is charged, and there are more opportunities for the developer to be charged than when it is new. For this reason, even when the developer deteriorates due to long-term use, the chargeability of the developer on the developer carrier can be maintained, and the developer can be stably charged from a new state for a long period of time. The background stain can be improved and the occurrence of abnormal images such as afterimages can be suppressed.

1 is a diagram showing a schematic configuration of an embodiment of an image forming apparatus to which the present invention is applied. FIG. 3 is a diagram illustrating a configuration of a process cartridge mounted on the image forming apparatus. FIG. 3 is an enlarged view showing a configuration of the developing device according to the present invention and a state when new. FIG. 3 is an enlarged view showing a state when the developing device according to the invention is deteriorated. The block diagram which shows the structure of the power supply meter with respect to a developing device. FIG. 7 is an enlarged view showing a configuration of a developing device in which a modified example of a contact member is adopted and a state at the time of deterioration. The figure which shows the solid follow-up defect evaluation result by run conditions.

  Embodiments of the present invention will be described below with reference to the drawings. According to the present invention, in a developing device using toner which is a one-component non-magnetic developer, the volume of the developer storage chamber changes as the remaining amount of toner decreases, and development is performed according to the change in the storage chamber. A contact member is provided so as to be able to contact and separate from a supply member that supplies toner to the agent carrier.

  First, the overall configuration and operation of the image forming apparatus will be described, and then the features of the present invention will be described. In each embodiment, constituent elements such as members and components having the same function or shape are given the same reference numerals as much as possible, and overlapping descriptions with the previous description are omitted as much as possible.

  FIG. 1 is a schematic diagram of a four-color full-color tandem type image forming apparatus. In the image forming apparatus, a document transport device 105 that transports a document above the apparatus main body 101 and a scanner unit 104 that serves as a document reading device are disposed, and a sheet S that serves as a recording member is fed to the lower portion of the apparatus main body 101. A paper portion 102 is arranged. In the apparatus main body 101, image formation is performed in which a digital signal output from the scanner unit 104 is electrically processed by an image processing unit, and an image is formed on a sheet based on the digital signal output from the image processing unit. Part 103 is arranged. In the scanner unit 104, an image of a document placed on the document placement table is read by a color CCD via an irradiation lamp, a mirror, and a lens, and the data is sent to the image processing unit. In the image processing unit, necessary processing is performed on the data, converted into an image signal, and sent to the image forming unit 103.

  The image forming unit 103 is opposed to the process cartridges 100K, 100Y, 100M, and 100C corresponding to black (K), yellow (Y), magenta (M), and cyan (C), and the process cartridges 100K, 100Y, 100M, and 100C. An intermediate transfer unit 106 including an intermediate transfer belt 121 that is an intermediate transfer belt 121 that is arranged and to which toner images formed by the process cartridges 100K, 100Y, 100M, and 100C are transferred, and transfer from the intermediate transfer belt 121 to the sheet S A fixing unit 107 that fixes the toner image to the sheet S is provided. The intermediate transfer belt 121 is wound around a plurality of roller members 111, 112, and 113, and is configured to move in the clockwise direction in the figure.

  On the intermediate transfer belt 121, primary transfer rollers 108K, 108Y, 108M, and 108C serving as primary transfer members are disposed at positions facing the process cartridges 100K, 100Y, 100M, and 100C to form a primary transfer portion. A secondary transfer roller 124 serving as a secondary transfer member is disposed at a position facing the roller member 111 to form a secondary transfer portion.

  As shown in FIG. 2, the process cartridges 100K, 100Y, 100M, and 100C include photosensitive drums 1K, 1Y, 1M, and 1C that are image carriers. Around each of the photosensitive drums 1K, 1Y, 1M, and 1C, charging rollers 2K, 2Y, 2M, and 2C that are contact charging members for charging the surface of the drum, and the photosensitive members that are uniformly charged by the charging rollers. One-component non-magnetic toner (hereinafter referred to as “toner”) used as a developer on an exposure portion irradiated with laser beams 3K, 3Y, 3M, and 3C, which is irradiated with a laser beam for forming a latent image on the surface of the body drum "Developing devices 5K, 5Y, 5M, and 5C that form toner images by charging and adhering T", and cleaning devices 12K, 12Y, 12M, and 12C for removing residual toner on each photosensitive drum. Are arranged in order. A toner replenishing container 4K, 4Y, 4M, and 4C that stores replaceable toner T and is connected to the developing devices 5K, 5Y, 5M, and 5C and supplies the toner T into each developing device is disposed above each developing device. Is arranged. Among these configurations, each photosensitive drum, each charging roller, each developing device, and each cleaning device is configured as a unit having the same color, and each of the process cartridges 100K, 100Y, 100M, and 100C of each color is provided. It is composed.

  The paper feed unit 102 is fed with a plurality of paper feed trays 140 and 140, paper feed rollers 142 and 142 for feeding the paper S stacked and stored in the paper feed trays 140 and 140, and the paper fed. Conveying rollers 143 and 143 that convey the sheet S toward the registration rollers 144 arranged in the apparatus main body 101 are provided.

  In the tandem type image forming apparatus having such a configuration, monochrome images such as black (K), yellow (Y), magenta (M), and cyan (C) are mainly transferred to the photosensitive drums 1K, 1Y, 1M, and 1C. Form on the surface. When the image formation is performed by a negative positive method (lowering the exposure part potential and attaching the toner), the photoreceptors 1K, 1Y, 1K, 1Y, 1E, whose surfaces are uniformly negatively charged by the charging rollers 2K, 2Y, 2M, and 2C. In 1M and 1C, an electrostatic latent image is formed on the surface of the photosensitive member by exposure 3K, 3Y, 3M, and 3C, and toner T is attached to the surface of the photosensitive member by developing devices 5K, 5Y, 5M, and 5C to visualize the toner image. To do. The toner image is transferred from the surface of each photosensitive drum to the intermediate transfer belt 121 by the primary transfer rollers 108K, 108Y, 108M, and 108C to which a transfer bias is applied, and is not transferred from each photosensitive drum to the intermediate transfer belt 121. The remaining toner components are removed from the surface of the photoreceptor by the cleaning blades 11K, 11Y, 11M, and 11C included in the cleaning devices 12K, 12Y, 12M, and 12C. The toner image transferred to the surface of the intermediate transfer belt 121 is transferred to the paper S conveyed from the paper feed tray 40 by applying a secondary transfer bias to the secondary transfer roller 124. The residual toner component or the external additive component after the transfer is removed by a cleaning member 123 provided in the cleaning device 122. The toner image transferred onto the paper S is transported to the fixing device 107 by the transport device 125 and is fused and fixed on the paper S by the fixing device 107. The fixed sheet S is discharged from a discharge roller 147 onto a discharge tray 148. In the image forming apparatus, such a series of image forming processes is executed for the set number of printed sheets, thereby completing the printing. In the figure, reference numeral 15 denotes a sensor used to adjust the image density and alignment by measuring the amount of toner deposited on the intermediate transfer belt 121 and the position of each color.

  1 and 2 show a full-color image forming apparatus using four-color process cartridges, the present invention is naturally applicable to a monochrome image forming apparatus using one process cartridge.

  Next, the configuration of the developing device, which is a characteristic part of the present invention, will be described with reference to FIGS. Since the developing devices of the respective colors have the same configuration except that the colors of the toners are different, the symbols Y, M, C, and K for identifying the colors are omitted, and one developing device 5 will be described as a representative. .

  FIG. 3 shows a state when the developing device 5 is new, and FIG. 4 shows a state when the toner T is reduced and deteriorated. In the developing device 5, the inside of the casing 5 </ b> A is divided into a developer storage chamber (hereinafter referred to as “toner storage chamber”) 41 and a developing chamber 42 in the vertical direction. In this embodiment, the developing chamber 42 is disposed on the lower side of the casing 5A, and the toner storage chamber 41 is disposed on the upper side of the casing 5A located above the developing chamber 42. The toner storage chamber 41 and the developing chamber 42 are partitioned by a partition member 410 that can move in the vertical direction, and the volume of the toner storage chamber 41 can be varied by moving the partition member 410 in the vertical direction. Has been.

  In the developing chamber 42, a developing roller 43 serving as a developer carrying member disposed opposite to the photosensitive drum 1, a supply roller 46 serving as a supply member that supplies toner T to the developing roller 43, and a developing roller A doctor blade 44 serving as a regulating member for regulating the layer thickness of the toner T held on the surface of the developing roller 43 by contacting the surface of the developing roller 43 to regulate the amount of toner T attached, and a contact member 45 are provided. . The developing roller 43 and the supply roller 46 are arranged so that the surfaces thereof are in contact with each other. The developing roller 43 and the supply roller 46 are rotatably supported by the casing 5A, and are configured to rotate in the same direction by a driving force from a driving source (not shown). That is, the surface movement direction of the developing roller 43 and the surface movement direction of the supply roller 46 are configured to be opposite to each other at the contact portion N1.

  The partition member 410 moves in the vertical direction according to the amount (weight) of toner stored in the toner storage chamber 41. A toner supply port 411 that connects the toner storage chamber 41 and the developing chamber 42 is formed in the center of the partition member 410. The upper ends 410b and 410c of the partition member 410 are supported on the upper surface 41A of the toner storage chamber 41 by a return spring 49 serving as an elastic member, for example, so that the partition member 410 can be displaced vertically. That is, the partition member 410 is supported on the inner wall surface of the toner storage chamber 41 so as to be slidable in the vertical direction.

  The partition member 410 occupies the first position shown in FIG. 3 when the process cartridge 100 is new and the amount of toner in the toner storage chamber 41 is not full, and the toner T is used and the remaining amount of toner T is used. When (capacity) decreases to a specified amount (predetermined amount) or less, it is configured to move upward by the pulling force of the return spring 49. That is, the volume of the toner storage chamber 41 decreases as the remaining amount of toner decreases.

  A toner stirring member 48 is arranged in the toner storage chamber 41. The toner T stored in the toner storage chamber 41 is agitated by the toner agitating member 48 and is supplied by dropping into the developing chamber 42 from the toner supply port 411. The toner stirring member 48 is supported by the partition member 410 and is configured to move together with the movement of the partition member 410. This is to keep the positional relationship between the toner stirring member 48 and the partition member 410 constant and prevent interference with the toner stirring member 48 when the partition member 410 moves. The toner agitating member 48 and the partition member 410 may not be configured to move integrally as long as a space where the both do not interfere with each other can be secured when the partition member 410 moves. However, in this case, since the developing device 5 is increased in size in the vertical direction, it can be said that the toner stirring member 48 is preferably provided so as to move integrally with the partition member 410.

  The partition member 410 is formed with an arm portion 412 that extends into the developing chamber 42. A contact member 45 is provided at a tip 412 a that is a part of the arm portion 412. The contact member 45 has a square cross section and has a block shape extending in the generatrix direction of the supply roller 46. When the toner amount in the toner storage chamber 41 is full and the partition member 410 occupies the first position shown in FIG. 3, the contact member 45 is at a position separated from the surface of the supply roller 46, and the toner storage chamber 41. When the partition member 410 moves upward and occupies the second position shown in FIG. 4, the amount of toner inside is reduced, and is arranged to occupy a position in contact with the surface of the supply roller 46.

  The developing device 5 is provided with a regulating means 450 that regulates a variable amount of the toner storage chamber 41 when the toner T in the toner storage chamber 41 becomes a predetermined amount (predetermined amount) or less. The restricting means 450 includes a lock member 452 that is inserted into a recess 451 formed in the casing 5A so as to freely advance and retreat, and a bias that biases the lock member 452 in a direction in which the lock member 452 protrudes from the recess 451 toward the side surface 410a of the partition member 410. A compression spring 453 is provided as means.

  On the side surface 410 a of the partition member 410, a storage portion 413 for storing the lock member 452 protruding from the recess 451 is formed so as to be recessed in the protruding direction side of the lock member 452. When the partition member 410 is in the first position shown in FIG. 3, the storage portion 413 faces the side surface 410a without facing the lock member 452, and the toner T decreases and the partition member 410 moves upward. When it occupies the second position shown in FIG. 4, it is arranged and configured to face the lock member 45. That is, the restricting means 450 restricts the change of the toner storage chamber 41 by stopping the movement of the partition member 410 when the toner T in the displaceable toner storage chamber 41 becomes less than a predetermined amount (predetermined amount). It has a function.

  As shown in FIG. 5, a bias is applied to the developing roller 43, the supply roller 46, and the contact member 45 from a power source 50, respectively. The bias applied to the developing roller 43 is a so-called developing bias, and the bias is set so that the negatively charged toner T becomes an electric field in a direction in which the toner T moves from the supply roller 46 to the developing roller 43 at the contact portion N1. Yes.

  In this embodiment, when the applied bias to the contact member 45 is Vt and the applied bias to the supply roller 46 is Vs, the relationship of the applied bias is set so that Vt | ≧ | Vt |. That is, the relationship between the applied bias Vt applied to the contact member 45 and the applied bias Vs applied to the supply roller 46 is an electric field in a direction in which the toner T charged to a negative polarity moves from the contact member 45 to the supply roller 46 at the contact portion N2. Is set to The absolute value of the bias applied to the contact member 45 is desirably 30 V or more larger than the absolute value of the bias applied to the supply roller 46. That is, | Vt | − | Vs | ≧ 30V. By setting the relationship between the applied biases as described above, the potential of the toner T can be increased by applying a potential difference between the contact member 45 and the supply roller 46.

Next, a process until a toner thin layer is formed on the developing roller 43 in the developing device 5 will be described.
When the process cartridge (developing device 5) is new and the toner T in the toner storage chamber 41 is full, the partition member 410 is in the first position shown in FIG. doing. In this state, when the developing roller 43 and the supply roller 46 rotate and a bias is applied to each of them, the toner T in the developing chamber 42 is attracted and held on the surface of the supply roller 46, and the supply roller 46 rotates. Conveyed in the direction. The toner T held and conveyed on the supply roller 46 reaches the contact portion N1 between the supply roller 46 and the developing roller 43, and is rubbed and charged by the contact portion N1. At the contact portion N1, the surface movement direction of the supply roller 46 and the surface movement direction of the developing roller 43 are opposite to each other, so that the toner T on the supply roller 46 is easily collected on the developing roller 46 side. Further, since the electric field in the direction in which the negatively charged toner T moves from the supply roller 46 to the development roller 43 is acting on the developing roller 43, more precisely, the contact portion N1, the charged toner T is supplied to the supply roller 46. 46 to the developing roller 43.

  The toner T thus charged is held on the developing roller 43 and conveyed to the contact portion N3 between the doctor blade 44 and the developing roller 43. The toner T is rubbed at the contact portion N3 between the developing roller 43 and the doctor blade 44 and further charged. The relationship between the bias between the doctor blade 44 and the developing roller 43 is set so that an electric field in the direction in which the negatively charged toner moves to the developing roller 43 is set, so that the charged toner T is placed on the developing roller 43. It is held and conveyed to a development area that is a portion facing the photosensitive drum 1.

  On the other hand, when the toner stirring member 48 of the toner storage chamber 41 rotates as the toner T in the developing chamber 42 is consumed, the toner T is supplied from the toner storage chamber 41 to the developing chamber 42 side through the toner supply port 411. The That is, the toner weight decreases as the toner in the toner storage chamber 41 is consumed, and the partition member 410 is moved upward in FIG. 3 to reduce the volume of the toner storage chamber 41 by the action of the return spring 49. Moving. As shown in FIG. 4, when the second position is reached, the lock member 452 and the storage portion 413 that have been prevented from moving by the side surface 410 a face each other, and the lock member 452 protrudes from the recess 451 so that the storage portion 413. Enter inside. As a result, the partition member 410 is fixed at the second position, and the contact member 45 is held in contact with the surface of the supply roller 46. That is, the contact member 45 comes into contact with the supply roller 46 after the volume change of the toner storage chamber 41, specifically, when the toner T in the toner storage chamber 41 falls below a specified amount (predetermined amount), and restricting means. The contact state with the supply roller 46 is maintained by 450. For this reason, even when the deterioration of the toner T progresses, the toner T can be stably charged at the contact portion N2.

  In this state, when the developing roller 43 and the supply roller 46 rotate and a bias is applied to the developing roller 43, the supply roller 46, and the contact member 45, the toner T in the developing chamber 42 is applied to the surface of the supply roller 46. It is sucked and held and conveyed in the rotation direction of the supply roller 46. Then, when passing through the contact portion N <b> 2 between the supply roller 46 and the contact member 45, it is frictionally charged and charged. The bias applied to the contact member 45 and the supply roller 46 is such that the electric field Vt | ≧ | Vt | in the direction in which the negatively charged toner T moves from the contact member 45 to the supply roller 46 at the contact portion N2. Therefore, the charged toner T moves from the contact member 45 to the supply roller 46.

  The charged toner T is held on the supply roller 46, moves to the development roller 43 at the contact portion N1 between the development roller 43 and the supply roller 46, and is rubbed at the contact portion N3 between the development roller 43 and the doctor blade 44. The toner is further charged, held on the developing roller 43, and conveyed to a developing area that is a portion facing the photosensitive drum 1.

  By such a process, a thin toner layer is formed on the developing roller 43. In addition, when the developing device 5 is in a new state, the toner T in the developing chamber 42 is not deteriorated and can be appropriately charged at the contact portion N3 between the developing roller 43 and the doctor blade 44, which is a general configuration. When the developing device 5 is used and the toner T deteriorates, the contact portion N2 between the contact member 45 and the supply roller 46 is charged, so that the toner T on the developing roller 43 is transferred. Charge amount becomes larger than before deterioration.

  For this reason, even when the toner T deteriorates due to long-term use, the charging property of the toner T on the developing roller 43 can be maintained, and the charging of the toner T can be stabilized for a long time from a new state. It is possible to prevent the occurrence of abnormal images such as afterimages as well as to improve the stains.

  As shown in FIGS. 3 and 4, in the developing device 5, the contact member 45 is a block having a square cross section and extending in the generatrix direction of the supply roller 46, but the contact member 45 according to the present invention is like this. For example, as shown in FIG. 6, a roller shape having a circular cross section and extending in the generatrix direction of the supply roller 46 may be used. The roller-shaped supply member 45 </ b> A is rotatably supported at the tip of the arm member 412. In the case of this embodiment, the roller-shaped contact member 45A is configured to be driven to rotate when contacting the supply roller 46 that is rotationally driven. That is, the contact member 45 </ b> A is configured to rotate in the direction opposite to the rotation direction of the supply roller 46 and the mutually opposing portion. With such a configuration, the stress applied to the toner T between the contact member 45A and the supply roller 46 can be reduced.

Next, each member will be described.
The doctor blade 44 serving as a regulating member uses a metal such as SUS304CSP, SUS301CSP, or phosphor bronze.
The supply roller 46 has a configuration in which a foam material 46b is coated on the outer periphery of the cored bar member 46a. The foam material 46b is set to an electric resistance value of 10 to the 14th power.
The developing roller 43 uses a roller member in which the outer periphery of the cored bar member 43a is covered with an elastic rubber layer 43b. The elastic rubber layer 43b is set to have an electric resistance value of the third to the 12th power of 10 of the volume resistance.
For the contact members 45 and 45A, a metal such as SUS304CSP, SUS301CSP, or phosphor bronze is used. In order not to apply excessive stress to the toner T, the contact pressure (linear pressure) at the contact members 45 and 45A, the supply roller 46, and the contact portion N2 is desirably 10 N / m or less.

  In the above embodiment, the toner T is replenished directly from the toner replenishing containers 4K, 4Y, 4M, and 4C into each developing container. However, a replenishment path is provided in the apparatus main body 101, and the replenishment path is provided through the replenishment path. A configuration may be used in which toner is supplied to each of the developing devices 5K, 5Y, 5M, and 5C.

  Also in the case of such an additional supply type developing device, when new toner is supplied into the toner storage chamber 41 from the toner supply containers 4K, 4Y, 4M, and 4C, the toner T in the development chamber 42 is temporarily charged. However, since the deteriorated toner is mixed, the charge amount of the toner T is remarkably reduced. Therefore, even after the replenishment of new toner, the contact members 45, 45A and the supply roller 46 are brought into contact with each other to apply sufficient charge to the toner T to increase the charge, so that even when the toner T deteriorates due to long-term use. The charging property of the toner T on the developing roller 43 can be maintained, the charging of the toner T can be stabilized for a long time from a new state, the solid follow-up failure and the background stain are also improved, and an abnormal image such as an afterimage is generated. Can also be suppressed.

The Example and comparative example concerning this invention are demonstrated using FIG.
FIG. 7 is a diagram showing an evaluation result when a solid toner is determined to be poor following by using a color laser printer IPSIO SP C310 manufactured by Ricoh Co., Ltd. and modifying the developing device of the black toner process cartridge into the developing device of the present invention. It is.
In FIG. 7, the run condition indicates a condition when the developing device is operated. The run conditions include the configuration of the developing device, the presence / absence of the regulating means 450, the bias applied to the contact members 45 and 45A, and the contact pressure (linear pressure) between the contact members 45 and 45A and the supply roller 46. As a configuration of the developing device, one having a block-shaped contact member 45 shown in FIG. 3 and one having a roller-shaped contact member 45A shown in FIG. 6 were used.

The above configuration is passed in a mode in which a chart with a printing rate of 1% is intermittently printed, and every 1000 sheets printed, up to 3000 sheets, development bias of −300 V, supply bias of −100 V (relative to development bias), regulation bias Two solid images were continuously printed at −100 V (vs. developing bias), and the blur rank of the second solid image was evaluated in five stages. (Rank 5 is the highest. Rank 4 and above is OK.)
Those with evaluations 4 and 5 from FIG. Example 1 and Comparative Example 3 and Example 3 and Comparative Example 4 differ only in the contact pressures of the contact members 45 and 45A, respectively. From these comparisons, when the contact pressure of the contact members 45 and 45A is high, the rank of the 3000th sheet is better when the contact pressure is lower. This is presumably because the lower the contact pressure, the lower the stress on the toner.

  Example 1 and Example 3 differ in the shape of the contact member. From these comparisons, the rank in the 200th sheet was higher and better in the roller-shaped contact member 45A than in the case where the block-shaped contact member 45 was used. This is considered that the use of the roller contact member 45A reduces the stress on the toner.

  The first embodiment and the second embodiment are different in whether or not the restriction means 450 is provided. From these comparisons, the rank on the 3000th sheet was higher and better than the case where the restriction means 450 was not provided. This is considered to be because the contact member 45 is in stable contact with the supply roller 46 and the charge is favorably applied to the deteriorated toner.

  Example 1 and Comparative Example 2 differ in whether or not there is a contact member. When the contact member 45 is provided as in the first embodiment, the rank is less decreased even when the number of printed sheets is increased as compared with the case where the contact member 45 is not provided. This is considered to be because the electric charge was favorably imparted to.

  In view of such considerations, by providing at least the contact member 45, it is possible to favorably impart charge to the deteriorated toner, and it is more preferable that the toner is further deteriorated if the regulating means 450 is further provided. Can be charged. Further, it can be said that the stress on the toner can be reduced by setting the contact pressure to 0 <contact pressure ≦ 10 N / m.

5K, 5Y, 5M, 5C Developing device 41 Developer storage chamber 43 Developer carrier 44 Restriction member 45 Contact member 46 Supply member 100K, 100Y, 100M, 100C Process cartridge 450 Restriction means N2 Contact portion T Developer

JP 2007-286399 A

Claims (8)

A developer carrier;
A supply member for supplying a developer to the developer carrier;
A regulating member for regulating the amount of developer on the developer carrying member;
A developer storage chamber in which the developer is stored and the volume of the developer changes according to the amount of developer stored;
A contact member movable according to a change in volume of the developer storage chamber;
The developing device according to claim 1, wherein the contact member is in contact with the supply member after the volume of the developer storage chamber is changed. When a bias is applied to each of the contact member and the supply member, an applied bias to the contact member is Vt, and an applied bias to the supply member is Vs,
The developing device according to claim 1, wherein | Vt | ≧ | Vs |. When a bias is applied to each of the contact member and the supply member, an applied bias to the contact member is Vt, and an applied bias to the supply member is Vs,
2. The developing device according to claim 1, wherein | Vt | − | Vs | ≧ 30V. The contact member and the supply member are rotatable roller members,
The developing device according to claim 1, wherein the contact member rotates in a direction opposite to a rotation direction of the supply member and opposite to each other.   5. The developing device according to claim 1, wherein a linear pressure of a contact portion between the contact member and the supply member is 10 N / m or less.   6. The apparatus according to claim 1, further comprising a restricting means for restricting the change of the developer storage chamber when the developer in the displaceable developer storage chamber becomes a predetermined amount (predetermined amount) or less. The developing device according to claim 1.   A process cartridge comprising the developing device according to any one of claims 1 to 6.   An image forming apparatus comprising the process cartridge according to claim 7.

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