Patent Application
20170299978
The present disclosure relates to image forming apparatuses, such as an electrophotographic printer and an electrophotographic copying machine.
Image forming methods used in image forming apparatuses such as a copier, regularly include an electrophotographic recording method. In such a method, a front surface of a photosensitive drum, which is an image carrying member, is uniformly charged with a charging device, an electrostatic latent image is formed with an exposing device, and the electrostatic latent image is visualized into a toner image using toner, which is a developer, with a developing apparatus. Subsequently, the toner image is transferred to a recording material, such as paper, with a transfer device, such as an intermediate transfer body, and, ultimately, is fixed with a fixing device. Meanwhile, the remaining toner that had not been transferred to the transfer material from the photosensitive drum is collected by a cleaning device abutted against the photosensitive drum.
Regarding the developing apparatus, Japanese Patent Laid-Open No. 6-43745 discloses an apparatus that employs a method in which a non-magnetic mono-component toner accommodated inside a developer container is supplied to a developing roller, which is a developer carrying member, with a supply roller, in which the thickness of the toner on the developing roller is made substantially uniform with a developing blade, which is a developer regulating member, and in which an electrostatic latent image is developed.
Furthermore, Japanese Patent Laid-Open No. 8-44206 proposes a developing apparatus that, while configured to use a non-magnetic single-component toner, does not use a supply roller. The above configuration includes a supply guide that abuts against a developing roller. The toner is conveyed and accumulated in a space formed between the developing roller and the supply guide, and the toner is supplied with a synergistic effect between the toner self-weight and the rotary force of the developing roller.
Moreover, regarding the developing roller, Japanese Patent Laid-Open No. 6-130792 proposes a developing roller employing a method in which portions that have different electric resistances or dielectric constants are exposed and mixed on a front surface thereof at a regular and fixed pattern pitch, and in which a number of micro electric fields are formed on the front surface thereof. By employing the above method, an appropriate amount of toner can be adhered to the electrostatic latent image on the photosensitive drum; accordingly, an image that has high image density and that has an excellent diagram reproducibility and gradation can be obtained.
Note that in the developing roller described above in which portions with different dielectric constants are provided on the front surface, there are cases in which the electric resistance of the dielectric unit dependent on the environment changes depending on the material of the dielectric unit such that the toner adhesion amount on the developing roller changes according to the environment in which the developing roller is used. In order to overcome such a problem, Japanese Patent Laid-Open No. 4-31880 discloses a technique in which a material having a smaller variation difference in the volume resistivity of the dielectric unit is used.
However, with the method using a supply roller, since, other than the developer carrying member (a developing roller), a mechanism for rotating the supply roller is needed and, furthermore, since there is a limit to the extent to which the supply roller can be miniaturized, it is difficult to achieve miniaturization and simplification of the overall developing apparatus.
On the other hand, with the method that does not use a supply roller, while the above problem is alleviated, it will be difficult to supply the developer to the developer carrying member in a stable manner.
In other words, when the pressure of the developer against the front surface of the developer carrying member is insufficient, cases in which the developer required to form an image not being sufficiently carried onto the developer carrying member occur.
On the other hand, if the pressure of the developer against the developer carrying member is too high, aggregated developer becomes easily formed in the vicinity of the developer carrying member. Since the aggregated developer hinders the developer from being supplied to the developer carrying member, there are cases in which the developer is not sufficiently carried onto the developer carrying member.
Furthermore, in the case of the apparatus configuration that does not use the supply roller, the electric resistances of the dielectric units on the front surface of the developing roller disadvantageously changes according to the environment in which the developing roller is used such that, disadvantageously, the toner coat amount on the developing roller changes according to the environment. It is considered to be one of the effective techniques to use a material that has, in the volume resistivity of the dielectric unit, a small variation difference in order to overcome the above problem.
However, the technique of suppressing the resistance variation of the dielectric through the material that is used limits the material that can be used. There are cases in which it is difficult to make the developing roller, which is capable of being mass manufactured inexpensively, to have a desired characteristic; accordingly, a limit is met in the application thereof when balancing with mass productivity.
The present disclosure has been made after a diligent study to overcome the above problem and provides a developing apparatus that, while being configured to supply developer to the developer carrying member in a simple manner, is capable of supplying the developer to a developer carrying member in a stable manner.
The present disclosure provides the following image forming apparatuses and the like.
A developing apparatus including developer, a developer container that accommodates the developer, a developer carrying member that is rotatably supported by the developer container, and that carries the developer, a conveying member that is provided inside the developer container, the conveying member including a shaft portion and a conveying portion connected to the shaft portion, and a restriction portion that restricts the developer carried on the developer carrying member, the restriction portion being disposed so as to oppose the developer carrying member among an area around the developer carrying member, an area where the front surface of the developer carrying member moves gravitationally upwards during an image-forming period. In the developing apparatus, the conveying member moves during at least a portion of a non-image-forming period, and stops and takes a stop position during at least a portion of the image-forming period, and, in the stop position, a straight line, drawn from a base end of the conveying portion that is an end portion on a shaft portion side towards a tip of the conveying portion, intersects a surface of the developer carrying member opposing the inside of the developer container at a portion upstream in a rotation direction of the developer carrying member with respect to the restriction portion.
An image forming apparatus, including the developing apparatus according to the above, and a control unit that performs control such that the conveying member is in the stop position.
A developing apparatus used in an image forming apparatus, including a frame body that accommodates developer, a developer carrying member rotatably disposed in an accommodating chamber of the developer, the developer carrying member carrying the developer, a first member that is disposed so as to abut against or be positioned close to a front surface of the developer carrying member at a portion above a rotating shaft of the developer carrying member, and a second member that is disposed so as to be positioned close to the front surface of the developer carrying member at a position upstream of the first member in a rotation direction of the developer carrying member and below the first member. In the developing apparatus, a distance in the rotation direction between a first position where the first member abuts against or is proximate to the front surface of the developer carrying member, and a second position where the second member is proximate to the front surface of the developer carrying member can be changed, and while the developing apparatus is performing an image forming operation, the distance is maintained.
A developing apparatus used in an image forming apparatus, including a flexible container that forms an accommodating chamber in which developer is accommodated, a movable member provided so as to be movable outside the container, wherein by moving, the position abutted against the container changes such that a shape of the container can be changed, a developer carrying member that is rotatably disposed in the developer chamber, and that carries the developer, and a restriction member that is disposed above a rotating shaft of the developer carrying member so as to abut against or be positioned close to a front surface of the developer carrying member. In the developing apparatus, the container is configured so as to be capable of changing a position of a proximity portion that approaches the front surface of the developer carrying member at a portion upstream with respect to the restriction member in a rotation direction of the developer carrying member and below the restriction member by deformation caused by a movement of the movable member, and a distance in the rotation direction between the proximity portion and a position where the restriction member abuts against or is proximate to the front surface of the developer carrying member is capable of being changed.
A developing apparatus used in an image forming apparatus, including a frame body that accommodates developer, a developer carrying member rotatably disposed in an accommodating chamber of the developer, the developer carrying member carrying the developer, a first restriction member that is disposed so as to abut against a front surface of the developer carrying member at a portion above a rotating shaft of the developer carrying member, and a second restriction member that, at a position upstream with respect to the first restriction member in a rotation direction of the developer carrying member and at a position below the first restriction member, includes a first end portion that approaches the front surface of the developer carrying member, and a second end portion that is away from the front surface. In the developing apparatus, when viewed in a direction in which the rotating shaft of the developer carrying member extends, a distance between a point of contact between the front surface and the first restriction member, and an intersection between an extended virtual line connecting the first end portion and the second end portion of the second restriction member and the front surface is capable of being changed, and the distance is maintained while the developing apparatus is performing an image forming operation.
An image forming apparatus that forms an image on a recording material, including an image carrying member, the developing apparatus developing a latent image formed on the image carrying member into a developer image that is transferred to a recording material, and at least a control unit that controls the developing apparatus.
Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
b are diagrams for describing an arrangement of the developing roller, a restriction portion, and the toner conveying member of the first exemplary embodiment.
Hereinafter, a configuration of the present exemplary embodiment will be exemplified with reference to the drawings. Note that the dimensions, the materials, and the shapes of the components, the relative arrangement of the components, and the like that are described in the present exemplary embodiment are to be appropriately altered based on the configuration of the device to which the present disclosure is applied and on various conditions, and the scope of the present disclosure is not intended to be limited by the following exemplary embodiments.
Referring to
The process cartridge 1 includes a photosensitive drum 10 serving as an image carrying member that carries an electrostatic latent image, a charging roller 11 serving as a charging member, a cleaning device 5, and a developing apparatus 3. The developing apparatus 3 includes a developing roller 31 serving as a developer carrying member, and accommodates developer (hereinafter, referred to as toner) T that is a negatively charged non-magnetic mono-component developer. The developing apparatus 3 is configured so that the developing roller 31 is capable of being abutted against and separated from the photosensitive drum 10.
A predetermined direct current voltage is applied to the charging roller 11 from a voltage applying member 71 for a charging device provided inside the image forming main body 70. Furthermore, the charging roller 11 uniformly charges a front surface of the photosensitive drum 10.
An exposing device 2 serving as an optical member emits a modulated laser beam based on image information sent from an information processing device (not shown) onto the front surface of the photosensitive drum 10. Subsequently, an electrostatic latent image is formed on the front surface of the photosensitive drum 10.
A voltage applying member 72 for the developing apparatus applies a predetermined direct current voltage to the developing roller 31 so as to turn the electrostatic latent image into a visible image with the developing apparatus 3. Furthermore, the developing roller 31 comes into contact with the photosensitive drum 10, and the toner T contained in the developing apparatus 3 is developed on the front surface of the photosensitive drum 10 such that a visible image (hereinafter, referred to as a toner image) is formed.
Synchronizing with the formation of the toner image, a recording material P serving as a recording medium is conveyed from the cassette 76 serving as a feeding unit. A predetermined voltage is applied to a transferring roller 75 serving as a transfer member with a voltage applying member 73 for the transfer device in order to transfer the toner image on the photosensitive drum 10 to the recording material P.
Most of the toner image is transferred to the recording material P; however, a portion remains on the photosensitive drum 10. The remaining toner T is collected by the cleaning device 5.
Furthermore, a fixing device 60 serving as a fixing unit fixes, with heat and pressure, the toner image transferred to the recording material P. The recording material P on which fixing has been completed is discharged onto a sheet discharge tray 74.
After the above, formation of images is continued through repetition of a similar process. In the description hereinafter, an “image-forming period” refers to a period when an electrostatic latent image formed on the front surface of the photosensitive drum 10 based on the image information reaches a position (a developing position) where the photosensitive drum 10 and the developing roller 31 are in contact with each other and when the developing apparatus 3 is turning the electrostatic latent image into a toner image. A “non-image-forming period” refers to a period when the developing apparatus 3 is not turning an electrostatic latent image into a toner image.
Referring to
The developing apparatus 3 includes the toner T, the developing roller 31, a developer container 32 that accommodates the toner T, a toner conveying member 33 serving as a conveying member, and a developing blade 34 serving as a developer regulating member.
The toner T has a non-magnetic negative chargeability, and a material such as, for example, a non-magnetic styrene-acryl-based+polyester-based resin is used.
The developing roller 31 carries the toner T on the surface thereof and is disposed in an opening at the lower portion of the developer container 32. The developing roller 31 is supported by the developer container 32 so as to be rotational in an R1-direction about a central axis (not shown) serving as a rotation center.
The toner conveying member 33 is included inside the developer container 32. The toner conveying member 33 includes a shaft portion 33a, and a conveying portion 33b that is connected to the shaft portion 33a and that conveys the toner T. The shaft portion 33a is formed of high impact polystyrene (HIPS) and the like. The conveying portion 33b is formed of a thin elastic body, such as a polyethylene terephthalate (PET) sheet having a thickness of about 50 to 200 μm. The toner conveying member 33 is rotatable in an arrow R2 direction, and rotates so as to convey the toner T positioned gravitationally below the center of the shaft portion 33a towards the vicinity of the developing roller 31.
The developing blade 34 is formed of a metal plate, such as a stainless steel (SUS) plate having a thickness of 50 to 120 μm. The developing blade 34 abuts against the developing roller 31 at a contact pressure of about 10 to 50 gf/cm so as to restrict the toner T on the developing roller 31 to a substantially uniform thickness.
An opening sealing sheet 29 is provided downstream of the developing blade 34 in the rotation direction R1. The opening sealing sheet 29 is in contact with the developing roller 31 and prevents the toner T inside the developer container 32 from leaking out.
Note that the surface of the developing 31 extending in the rotation direction R1 from the position, serving as a starting point, where the opening sealing sheet 29 abuts against the developing roller 31 to the position where the developing blade 34 abuts against the developing roller 31 is defined as a “surface of the developing roller 31 facing the inside of the developer container 32”.
With the configuration described above, the developing apparatus 3 restricts the amount of toner T carried on the developing roller with the developing blade 34 and supplies the toner T to the photosensitive drum 10.
Before the image formation, the developing roller 31 and the photosensitive drum 10 are separated from each other with a gap of about 100 μm. When an image forming signal is sent, the image forming apparatus drives a drive input unit 36 of the developing apparatus 3 with a drive source (not shown) and rotates the developing roller 31. Subsequently, the developing apparatus 3 is moved about a pivot center 20 with an abutment and separation drive unit 65 (see
Toner carrying of the developing roller 31 will be described with reference to
Toner carrying of the developing roller 31 is performed by creating a toner circulation W and a toner reservoir S illustrated in
As illustrated in
Referring to
As illustrated in
Furthermore, by stopping the toner conveying member 33 at a predetermined position, the toner reservoir S is formed in the space formed by the developing roller 31 and the toner conveying member 33. Accordingly, the toner accumulated in the toner reservoir S can be carried by the developing roller 31.
In the above state, by arranging the center L of the shaft portion 33a of the toner conveying member 33 in the area 81, the toner conveying member 33 will be in a position to form the toner reservoir S more easily. Furthermore, desirably, the center L of the shaft portion 33a of the toner conveying member 33 is arranged gravitationally below the abutting portion 34N. By so doing, the toner reservoir S can be formed in a smaller space.
Note that in the present exemplary embodiment, while an example using the abutting portion 34N of the developing blade 34 as the restriction portion to form a desirable toner circulation W has been given, other configuration may be adopted. For example, as illustrated in
An operation of the toner conveying member will be described with reference to
The toner conveying member 33 interlocks with the abutting and separating operation of the developing roller 31 and the photosensitive drum 10, stops during at least a portion of the image-forming period, and rotates during at least a portion of the non-image-forming period.
Note that as it has been described above, the “image-forming period” refers to a period when an electrostatic latent image formed on the front surface of the photosensitive drum 10 based on the image information reaches a position (a developing position) where the photosensitive drum 10 and the developing roller 31 are in contact with each other and when the developing apparatus 3 is turning the electrostatic latent image into a toner image. The “non-image-forming period” refers to a period when the developing apparatus 3 is not turning an electrostatic latent image into a visible image.
The reason for stopping the toner conveying member 33 at the above timing and the reason for operating the toner conveying member 33 will be described below.
First of all, the toner conveying member 33 is stopped during the image-forming period to carry the toner on the developing roller 31 in a stable manner. As described above, in order to carry the toner in a stable manner, the toner circulation W and the toner reservoir S needs to be formed (see
While the toner conveying member 33 is in the stop position, the toner T is carried on the developing roller 31 with the toner circulation W and the toner reservoir S described above. Accordingly, the amount (a carrying amount) of toner carried by the developing roller 31 when the toner conveying member 33 is in the stop position is larger than when the toner conveying member 33 is in a position other than the stop position (in particular, at a position where no toner reservoir S is formed). In other words, the toner conveying member 33 in the stop position forming the toner reservoir S in the vicinity of the developing roller applies an appropriate toner pressure to the developing roller 31 so that the amount of toner T carried by the developing roller 31 can be increased.
Confirmation of whether the toner conveying member 33 in the stop position has increased the carrying amount of toner T on the developing roller 31 can be performed by measuring the carrying amount of toner T carried by the developing roller 31. Note that the stop position of the toner conveying member 33 may be a position that enables the carrying amount required for forming the image is obtained and a position in which the carrying amount is the largest does not have to be selected.
Furthermore, among other methods, another method to make a confirmation is to rotate and stop the toner conveying member 33 while directly observing the state of the above. In other words, it is only sufficient that the toner reservoir S is in contact with the developing roller 31 when the toner conveying member 33 is at a stop.
Moreover, a further easier method is to actually form images and check whether there are any defective images caused by insufficient toner carrying of the developing roller 31.
Note that the confirmation above includes confirmation that is performed using the amount of toner that is near the end of its life time, which is assumed during use of the developing apparatus 3.
The stop position of the toner conveying member 33 is, desirably, a position where the toner conveying member 33 is close to the developing roller 31.
When assuming that a straight line BF is drawn, as illustrated in
Furthermore, as illustrated in
Furthermore, as illustrated in
Referring now to
While the toner conveying member 33 is in the stop position, in a case in which the straight line drawn from the tip KF towards the base end KB extends gravitationally downwards (in a case in which the tip KF is oriented gravitationally upwards), when the inclination is large, the toner T disadvantageously falls in a direction away from the developing roller 31. Accordingly, in such a case, it is better that an angle θ1 formed between the straight line drawn from the tip KF towards the base end KB and the horizontal line is small, and it is desirable that the angle θ1 be smaller than the angle of repose of the toner T (
Furthermore, while the toner conveying member 33 is in the stop position, in a case in which the straight line drawn from the tip KF towards the base end KB extends gravitationally upwards (in a case in which the tip KF is oriented gravitationally downwards), it is desirable that the inclination be large. Furthermore, it is preferable that the angle θ formed between the straight line drawn from the tip KF towards the base end KB and the horizontal line be larger than the angle of repose of the toner T itself (
Moreover, while the toner conveying member is in the stop position, it is desirable that the toner conveying member 33 and the developing roller 31 be distanced away from each other. The above is to prevent the developing roller 31 and the toner conveying member 33 from becoming worn due to rotation of the developing roller 31 alone while the developing roller 31 and the toner conveying member 33 are in contact with each other. Note that in order to form a satisfactory toner reservoir S, the gap between the toner conveying member 33 and the developing roller 31 in the stop position is, desirably, about 2 mm or under.
Next, the reason for rotating the toner conveying member 33 during the non-image-forming period will be described with reference to
If the toner conveying member 33 is kept stopped and there is a lot of remaining amount of toner, as illustrated in
Furthermore, if the remaining amount of toner is small, as illustrated in
In the present exemplary embodiment, the rotation and stoppage of the toner conveying member 33 synchronizes with the separation and abutment between the photosensitive drum 10 and the developing apparatus 3. During the abutment (the image-forming period), a rotation gear (not shown) of the toner conveying member 33 is disengaged from the drive input unit 36 such that the toner conveying member 33 is stopped. On the other hand, during the separation (the non-image-forming period), the rotation gear of the toner conveying member 33 and the drive input unit 36 are engaged to each other such that the toner conveying member 33 is operated.
Accordingly, a control unit 99 (see
Another method of rotating and stopping the toner conveying member 33 will be described with reference to
The developing apparatus 3 includes a conveyance input member 37 to which drive from the drive input unit 36 is input and that drives the conveyance drive member 33c. The conveyance input member 37 is disposed so as to be coaxial with the conveyance drive member 33c. Furthermore, the conveyance input member 37 is connected to the conveyance drive member 33c while having a friction member 38 serving as a differential absorption member interposed between the conveyance input member 37 and the conveyance drive member 33c.
As illustrated in
As illustrated in
As illustrated in
On the other hand, as illustrated in
During the image-forming period, the conveyance input member 37 receiving a drive from the drive input unit 36 attempts to rotate the conveyance drive member 33c in an R2-direction through the friction member 38. However, since the conveyance position determination portion 33d abuts against the stopper member 39, the friction member 38 slips and the conveyance drive member 33c does not move.
On the other hand, when the photosensitive drum 10 and the developing roller 31 are separated from each other, as described above, the conveyance drive member 33c is capable of rotating freely. Accordingly, the conveyance input member 37 can rotate the conveyance drive member 33c through the friction member 38.
When the photosensitive drum 10 and the developing roller 31 are abutted against each other once more, the pressure of the abutment and separation drive unit 65 is released, the stopper member 39 is brought to the locked state once more, and the conveyance position determination portion 33d is stopped at a desired phase.
Note that the differential absorption member may be a member other than the friction member 38. Moreover, the conveyance drive member 33c, the conveyance position determination portion 33d, and the friction member 38 may be provided at positions different from those described in the present exemplary embodiment as long as the toner conveying member 33 can be positioned in the stop position.
In the present exemplary embodiment, the toner conveying member 33 is configured to interlock with the operation of separating and abutting the photosensitive drum 10 and the developing roller 31 from and against each other, and to stop the conveyance drive member 33c during the image-forming period. However, the present disclosure is not limited to the above configuration. In other words, it is only sufficient that the toner conveying member 33 can be positioned in the stop position during the image-forming period. For example, the toner conveying member 33 may be positioned in the stop position by controlling a separate drive member (a stepping motor or the like). Furthermore, the stopper member 39 may be moved by a separate drive member and a separate control unit.
Furthermore, in the present exemplary embodiment, the configuration of the toner conveying member 33 in which the conveying portion 33b rotates about the center of the shaft portion 33a has been described; however, other configurations may be adopted. In other words, it is only sufficient that the toner conveying member 33 is capable of mixing the toner T, and is capable of being stopped during the image-forming period such that the toner reservoir S is formed in the vicinity of the developing roller 31b. Accordingly, the conveying member 33 may be configured so that the conveying portion 33b swings, or so that a link mechanism or the like is connected to the shaft portion 33a so that the conveying member 33 reciprocates with respect to the developing roller 31.
As described above, in the configuration of the first exemplary embodiment of the present disclosure, by having the toner conveying member 33 operate during the non-image-forming period and stop during the image-forming period, the toner conveying member 33 is made to perform two roles, namely, mixing the toner and supplying the toner. With the above, aggregation of the toner T can be eliminated during the non-image-forming period by operating the toner conveying member 33, and the toner reservoir S can be formed during the image-forming period by stopping the toner conveying member 33. Furthermore, a desirable toner circulation W can be achieved with the abutting portion 34N. With the above, toner can be supplied while using the weight of the toner itself efficiently; accordingly, while miniaturization and simplification of the configuration of the developing apparatus 3 are achieved, supply of toner to the developing roller 31 can be performed in a stable manner.
A second exemplary embodiment of the present disclosure will be described with reference to
Note that in the present exemplary embodiment, description of components that are different from those of the first exemplary embodiment will be given, and description of components that are similar to those of the first exemplary embodiment will be omitted.
A feature of the present exemplary embodiment is that instead of the developing roller 31 described in the first exemplary embodiment, a developing roller 131 configured so that dielectric portions capable of holding a charge, and a conductive portion adjacent to the dielectric portions are provided having minute areas exposed and mixed in the front surface is used.
As illustrated in
A plan view of the developing roller 131 is illustrated in
The charge of the dielectric portions 131d described above becomes larger as the opportunity of sliding between the toner T and the developing roller 131 increases. In other words, as the movement of the toner T on the front surface of the developing roller 131 becomes larger, the amount charged in the dielectric portions 131d becomes larger. In order to increase the movement of the toner T on the front surface of the developing roller 131, all one has to do is to make the toner circulation W active, which has been described in the first exemplary embodiment. In order to make the toner circulation W active, one only has to provide the restriction portion (the abutting portion 34N and the like in the first exemplary embodiment) and operate the toner conveying member 33 in a similar manner to that of the first exemplary embodiment. With the above, the amount of charge in the dielectric portions is increased, and minute closed electric fields are formed in the adjacent portions between the dielectric portions and the conductive portion. Furthermore, the toner conveyed to the toner reservoir S in the vicinity of the developing roller 131 with the toner conveying member 33 receives gradient force and is drawn to and carried on the front surface of the developing roller 131.
As described above, in the present exemplary embodiment, not only the toner on the front surface of the developing roller 131 but the dielectric portions formed in the front surface of the developing roller 131 can be charged with the toner circulation W in the vicinity of the developing roller 131. Accordingly, more minute closed electric fields can be formed such that the gradient force drawing the toner increases and a large amount of toner can be carried.
A third exemplary embodiment of the present disclosure will be described with reference to
A feature of the present exemplary embodiment is that, in a case in which formation of images is performed continuously on a plurality of recording materials P, the toner conveying member 33 is moved during the formation of the image transferred to the preceding recording material P and during the formation of the image transferred to the succeeding recording material P. With the above, the toner in the vicinity of the developing roller 31 is loosened and the supplying of the toner to the developing roller 31 stabilized.
Note that components other than the toner conveying member are the same as those of the first and second exemplary embodiments. In the present exemplary embodiment, components that have configurations that are different from those described in the first exemplary embodiment will be described.
A pivot drive unit 90 that drives a pivoting member described later on the basis of image information sent from an information processing device (not shown) is provided in the image forming apparatus of the present exemplary embodiment. The pivot drive unit 90 is controlled with the control unit 99.
An operation of the toner conveying member 33 according to the present exemplary embodiment will be described with reference to
As described above, during the image-forming period, the toner conveying member 33 needs to be stopped such that the toner reservoir S is formed in the vicinity of the developing roller 31. However, if the toner conveying member 33 is kept stopped and there is a lot of remaining amount of toner, as illustrated in
Even in a case in which continuous printing is performed, from the end of the formation of the image transferred to the preceding recording material P to the start of the formation of the image transferred to the succeeding recording material P (hereinafter, merely referred to as “in-between-recording-materials period”), no images are formed. Accordingly, the toner conveying member 33 can be operated and the toner T can be loosened during the in-between-recording-materials period. Furthermore, during the image-forming period, the toner reservoir S can be re-formed in the vicinity of the developing roller 31 by stopping the toner conveying member 33 once more. In other words, supply of toner to the developing roller 31 can be stabilized without obstructing the image forming operation.
Note that the operation of the toner conveying member 33 during the in-between-recording-materials period may, as illustrated in
The pivotal movement of the toner conveying member 33 during the in-between-recording-materials period will be described with reference to
The pivoting member 92 that operates the toner conveying member 33 during the in-between-recording-materials period is provided in the vicinity of the toner conveying member 33. The pivoting member 92 includes a pivoting shaft 92a, a pivoting plate 92b that rotate and abuts against the conveying portion 33b, and a pivot input portion 92c. The pivoting shaft 92a is formed of HIPS or the like and is capable of being rotated in an arrow R4 direction by having the pivot input portion 92c receive an operational input from the pivot drive unit 90 illustrated in
Furthermore, a spring-like abutting member (not shown) that is capable of expanding and contracting in the longitudinal direction is provided in the pivot input portion 92c. The pivoting member 92 is capable of moving in the longitudinal direction by expansion and contraction of the abutting member.
The pivoting plate 92b is formed of a thin elastic body, such as a polyethylene terephthalate (PET) sheet having a thickness of about 50 to 200 μm. The length of the pivoting plate 92b in a direction extending in the radius of rotation and the length thereof in the rotational axis direction are both shorter than those of the conveying portion 33b of the toner conveying member 33. The pivoting plate 92b is configured to abut against the conveying portion 33b of the toner conveying member 33 in the stop position when the pivoting member 92 is rotated.
The pivoting member 92 receiving an operational input from the pivot drive unit 90 illustrated in
An operation of the pivoting member 92 during periods other than the in-between-recording-materials period is next described in
The pivoting member 92 receiving an operational input from the pivot drive unit 90 illustrated in
In the present exemplary embodiment, particularly, a configuration in which the toner conveying member 33 is pivotally moved using the pivoting member 92 has been described in detail; however, the present disclosure is not limited to the above configuration. The movement of the toner conveying member 33 during the non-image-forming period, as described in the first exemplary embodiment, may be performed during the in-between-recording-materials period.
As described above, by moving the toner conveying member 33 during the in-between-recording-materials period, the toner can be loosened and the supply of toner to the developing roller 31 can be stabilized without obstructing the image formation operation when the operation of continuously forming images on a plurality of recording materials is carried out.
A fourth exemplary embodiment of the present disclosure will be described with reference to
A feature of the present exemplary embodiment is that the operation of the toner conveying member is performed by a stepping motor or the like that operates while synchronizing with pulse power and that is capable of reverse rotation.
Note that components other than the toner conveying member are the same as those of the first and second exemplary embodiments.
The image forming apparatus is provided with a stepping motor 95 that rotates and stops the toner conveying member 133. The stepping motor 95 is controlled with the control unit 99.
A conveyance drive member 133c that receives the drive from the stepping motor 95 is provided in a shaft portion 133a of the toner conveying member 133. The conveyance drive member 133c and the stepping motor 95 are configured so as to be connected to a specific phase. Furthermore, the conveyance drive member 133c and a conveying portion 133b are also configured to be at a specific phase in the rotation direction of the toner conveying member 133.
In other words, the image forming apparatus according to the present exemplary embodiment is capable of independently controlling the operation and stoppage of the toner conveying member 133 with the stepping motor 95 and is capable of directly controlling the stop position of the toner conveying member 133.
During the image-forming period, the toner conveying member 133 is controlled so as to be in the stop position to form the toner reservoir S, such as the one described in the first exemplary embodiment. Furthermore, during the non-image-forming period, the toner conveying member 133 can be moved and the toner T can be loosened.
Moreover, the toner conveying member 133 can be rotated during the in-between-recording-materials period as well when images are formed on a plurality of recording materials. Furthermore, a motion of alternatively repeating a rotation in the forward direction and the rotation in the backward direction can be transmitted to the conveyance drive member 133c so that the toner conveying member 133 is moved towards the front and back in the rotation direction.
As described above, the toner conveying member 133 can be moved with a stepping motor 95, and the operation and stoppage of the toner conveying member 133 can be controlled. Accordingly, supply of toner to the developing roller 31 can be performed in a stable manner. Furthermore, the toner conveying member 133 can be moved and the toner T can be loosened during the in-between-recording-materials period. Accordingly, the supply of toner to the developing roller 31 can be stabilized without obstructing the image formation operation when formation of images on a plurality of recording materials is continuously carried out.
A fifth exemplary embodiment of the present disclosure will be described with reference to
A feature of the present exemplary embodiment is that the photosensitive drum 10, the charging roller 11, the cleaning device 5, and the developing apparatus 3 are incorporated in an integrated manner as a process cartridge PC that is detachable from the image forming apparatus main body.
By employing such a cartridge system, it goes without saying that a similar effect as that of the first exemplary embodiment can be obtained. Furthermore, the maintenance load can be reduced and an image forming apparatus with excellent usability can be provided.
Note that the process cartridge PC may be configured so as to be capable of being divided into a block BR-A and a block BR-B surrounded by broken lines.
The image forming apparatus to which the present disclosure is applied includes a copier, a laser beam printer (LBP), a printer, a fax machine, a microfilm reader-printer, and a recording machine, which employ an image forming process adopting an electrophotographic printing method. Such image forming apparatuses fixes an unfixed developer image that is formed and carried on a recording material (a transfer material, a printing sheet, photosensitive paper, electrostatic recording paper, etc.) by using an intermediate transfer system or a direct transfer system in an image forming process unit. Note that the left-right direction in each diagram coincides with the horizontal direction and the up-down direction coincides with the vertical direction. In other words, gravitational force acts from the upper side towards the lower side of each drawing.
Referring to
Referring to
The developing roller 31 carries the toner T and is disposed in an opening at the lower portion of the developer frame body 32. As illustrated in
The development frame body 32 accommodates the toner T and corresponds to a developer accommodating portion or the developing apparatus. The toner conveying member 33 includes a shaft portion 33a and a conveying portion (sheet-like portion) 33b. The shaft portion 33a is formed of HIPS or the like and is capable of rotating inside the developer accommodating chamber of the development frame body 32 in an arrow R2-direction. Upon rotation of the shaft portion 33a, the angle of the surface of the conveying portion 33b extending from the shaft portion 33a towards the developing roller 31 changes, and the position of the front surface of the developing roller 31 close to the toner conveying member 33 changes. The conveying portion 33b is formed of a thin elastic body, such as a polyethylene terephthalate sheet having a thickness of about 50 to 200 μm, and conveys the toner T to a portion close to the developing roller 31. The developing blade 34 constituted of a plate formed of metal, such as an SUS, having a thickness of about 50 to 120 μm abuts against the developing roller 31 at a contact pressure of about 10 to 50 gf/cm so as to restrict the toner on the developing roller 31 to a substantially uniform thickness. With the configuration described above, the developing apparatus 3 supplies the toner T that is carried by the developing roller 31 and in which the amount thereof has been restricted by the developing blade 34 to the photosensitive drum 10.
Before the image formation, the developing roller 31 and the photosensitive drum 10 are separated from each other with a gap of about 100 μm. Upon reception of an image forming signal, the image forming main body performs a driving input operation to a drive input unit 36 of the developing apparatus with a drive member (not shown) such that rotational drive is started. Subsequently, an abutting operation between the photosensitive drum 10 and the developing roller 31 is performed with an abutting and separating mechanism. In the present exemplary embodiment, while the developing roller 31 and the photosensitive drum 10 are abutted against each other, the drive input unit 36 meshed with a rotation gear of the developing roller 31 rotates the developing roller 31 (in an R3-direction). On the other hand, while the developing roller 31 and the photosensitive drum 10 are separated from each other, the drive input unit 36 meshes with a rotation gear of the toner conveying member 33 and rotates the toner conveying member 33 (in the R2-direction). In other words, the toner conveying member 33 is rotationally driven only during the separation and is stopped during the abutment. The reason for employing such a mechanism will be described later.
Referring to
A plan view of the front surface layer 31c of the developing roller 31 is illustrated in
Desirably, the size of each dielectric portions 31d (the size of the portion (a circular portion) that is exposed to the peripheral surface of the developing roller 31 (the conductive portion 31c1) is about 5 to 500 μm in diameter, for example. The above diameter is an optimum value for adhering the required toner on the developing roller 31 to maintain the charge on the front surface and suppress unevenness in the image. When diameter 5 μm holds true, a sufficient charge can be maintained and sufficient minute closed electric fields can be formed on the front surface of the dielectric portions 31d. When diameter <5 μm holds true, the amount of potential held on the front surface of the dielectric portions 31d is small and sufficient minute closed electric fields cannot be formed. Furthermore, when diameter >500 μm holds true, the potential difference between the dielectric portions 31d and the conductive portion 31c1 will become large and the image will become one with a lot of unevenness.
The charge of the dielectric portions 31d described above becomes larger as the sliding opportunity between the toner and the developing roller increases. In other words, as the movement of the toner on the front surface of the developing roller becomes larger, the amount charged in the dielectric portions 31d becomes larger. In order to increase the movement of the toner on the front surface of the developing roller, all one has to do is to make the toner circulation W active, which is illustrated in
Referring to
A feature of the present exemplary embodiment is that an environment detection member capable of detecting temperature and humidity is mounted in the image forming main body and the stop position of the toner conveying member 33, serving as a second restriction member, is determined according to the output value.
A temperature-humidity environment sensor 78 illustrated in
Referring to
First, the toner conveying member 33 is stopped during the image-forming period to form the toner coating on the developing roller 31 in a stable manner. In order to form a stable toner coating, the toner circulation W and the toner reservoir S described above and illustrated in
The factors that determine the toner coat amount on the developing roller before passing through the developing blade will be described next with reference to
(1) The larger the charge amount of the toner on the developing roller or the dielectric portions 31d, a larger gradient force is at work; accordingly, the toner coat amount increases.
(2) As a toner coating area V (the portion defined by the broken line in the drawing) that is an area in which the toner accumulated in the toner reservoir S formed with the toner conveying member, the developing roller, and the developing blade is in contact with the developing roller becomes larger, a toner suction opportunity increases; accordingly, the toner coat amount increases.
Note that the toner coating area V is an area that can be changed optionally by changing a distance (a gap) between K1 that is a point of contact (the proximate portion) between the developing blade 34 and the developing roller 31, and K2 that is a point of contact between an extended line of the toner conveying member 33 and the developing roller 31. Note that the extended line is a line obtained by extending a virtual line connecting a tip of a mixing portion (conveying portion) 33b, serving as a first end portion, and the shaft portion 33a, serving as a second end portion. Note that while the first position according to the present disclosure corresponds to K1 according to the present exemplary embodiment, the second position according to the present disclosure changes according to the position of the toner conveying member 33, and may coincide with K2 or may be, strictly speaking, a position different to K2. The aim of specifying such positions is to specify the area of the front surface of the developing roller 31 facing the toner retaining space, and in the present exemplary embodiment, description is given while deeming K2 to be at a position that is substantially the same as the second position of the present disclosure. The distance between K1 and K2 can be changed by changing the position of the portion of the developing roller 31 that is close to the toner conveying member 33 by rotating the toner conveying member 33. Furthermore, as described above, during the image forming operation, the rotation of the toner conveying member 33 is stopped; accordingly, the distance between K1 and K2 is maintained at a predetermined distance. Furthermore, the charge amount of the toner T or the dielectric portions 31d described in (1) above is known to vary under an environment during practical use. Specifically, the charge amount decreases as the environment becomes higher in temperature and higher in humidity, and increases as the environment becomes lower in temperature and lower in humidity. Accordingly, the toner coat amount also changes according to the environment in which the apparatus is used, and when on the high-temperature, high-humidity side, the coat amount decreases and when on the low-temperature, low-humidity side, the coat amount increases.
Accordingly, in the present exemplary embodiment, in accordance with a value of an absolute moisture content detected by the temperature-humidity environment sensor 78, the control unit 77 controls the drive unit, changes the stop position of the toner conveying member 33, and changes the toner coating area V. In other words, in a case in which the absolute moisture content acquired by the temperature and the humidity detected by the temperature-humidity environment sensor 78 is under a predetermined threshold (under a first threshold), the control unit 77, determining that it is a low temperature and low humidity environment, executes a control needed for a low temperature and low humidity environment described later. On the other hand, in a case in which the absolute moisture content acquired by the temperature-humidity environment sensor 78 is larger than a predetermined threshold (a second threshold), the control unit 77, determining that it is a high-temperature and high-humidity environment, executes a control needed for a high-temperature and high-humidity environment described later. In a case in which the absolute moisture content acquired with the temperature-humidity environment sensor 78 is equivalent to or higher than the first threshold and is equivalent to or lower than the second threshold, determining that it is a normal-temperature and normal-humidity environment, a state in which the toner coating area V suitable for the normal-temperature and normal-humidity environment is formed is maintained. With the above, the toner coat amount can be substantially uniformized regardless of the change in the environment. Tables 1 and 2 below are experimental results in which the toner coat amount before passing through the developing blade had been measured in a case in which the stop position of the toner conveying member was changed in accordance with the absolute moisture content and in a case in which the stop position of the toner conveying member was not changed.
In the present exemplary embodiment, the environment in which the absolute moisture content is from 0.5 g/m3 or higher to 15.0 g/m3 or lower is referred to as the normal-temperature and normal-humidity environment. In such a case, as illustrated in
As illustrated above, a developing apparatus that is capable of coating the appropriate amount of toner even when there is a change in the environment can be provided by controlling the stop position of the toner conveying member according to the detection result of the environment detection member. In the above table, each of the stop positions of the toner conveying member is varied by 10° with respect to the position proximate to the developing roller; however, the positions may be set in a more minute manner in accordance with the absolute moisture content obtained with the environment sensor. In such a case, for example, the stop positions corresponding to the absolute moisture contents are set in a minute manner in a recording memory of the image forming apparatus main body, and the value obtained with the environment sensor is matched with the stored stop positions and the toner conveying member is stopped at the corresponding stop position. Alternatively, the toner conveying member may be stopped at a position obtained by performing linear interpolation on the three stop positions in the above table and the absolute moisture content.
Furthermore, in the present exemplary embodiment, the rotation and stoppage of the toner conveying member synchronizes with the separation and abutment between the photosensitive drum 10 and the developing apparatus 3. In other words, during the abutment (during the image-forming period), the rotation gear of the toner conveying member is detached from the drive unit and the toner conveying member is stopped, and during the separation (during the non-image-forming period), the rotation gear of the toner conveying member and the drive unit are meshed to each other and the toner conveying member is operated. Accordingly, by controlling the separation time of the non-image-forming period, the control unit inside the image forming body is capable of controlling the stop position of the toner conveying member such that the toner conveying member can always be stopped at the same position during the image-forming period.
Referring to
As the developing apparatus repeats the image forming operation, the toner that remain inside the development frame body 32 without being used for the development of the latent images becomes deteriorated due to, for example, rubbing between the toner themselves, and being rubbed against the toner conveying member 33 and the developing blade 34. When the deterioration of the toner is accelerated, the toner drawing effect created by the minute closed electric fields on the front surface of the developing roller 31 decreases, and a sufficient toner coat amount may not be obtained in the latter half of the life time of the developing apparatus. Lack of toner coat amount may lead to a creation of a defective image. In the present exemplary embodiment, when the number of sheets printed (the number in which image formation has been executed), which can determine that the deterioration of toner has been accelerated, reaches a predetermined number, the toner suction opportunity is increased by enlarging the toner coating area V such that insufficiency in toner coat amount does not occur.
As illustrated above, when a certain number of sheets are printed, the state of the toner disadvantageously changes from the new state, and the toner circulation W illustrated in
Referring to
In the present exemplary embodiment, a detecting operation of the toner coat amount is executed when the power of the image forming apparatus is turned on. In performing the detection of the toner coat amount, in other words, in detecting the applied amount of toner per unit area, a patch of solid image of 5 mm by 5 mm is developed on the photosensitive drum 10 as an image for detection to detect the reflection density of the toner. The toner coat amount on the developing roller 31 is measured by reading the solid image with the concentration detecting sensor 51 disposed in the vicinity of the photosensitive drum 10. The detected reflection density obtained above is, as illustrated in
As described above, by controlling the stop position of the toner conveying member 33 according to the detection result of the toner coated state detecting member, it will be possible to correct the coat amount to the desired toner coat when there is a change in the toner coat amount.
In the present exemplary embodiment, turning on of the image forming apparatus serves as a trigger to execute the present control; however, a detection of the change in the temperature or the humidity detected by the environment sensor, for example, may be the trigger to execute the present control.
Since the present control performs correction after detecting the actual state of the toner coated on the developing roller, in a case in which excessive toner is coated, an adverse effect such as generation of a fog, which is caused by supplying toner to a portion where no image is normally formed, may disadvantageously occur. When developing a solid image on the photosensitive drum, toner may become adhered to portions where no image is normally formed, and a problem such as consuming toner in a wasteful manner may occur. Accordingly, it is desirable that the control is executed in combination with the configuration of the sixth exemplary embodiment. By so doing, rough tuning may be performed through the control of the environment sensor having the configuration of the sixth exemplary embodiment, and fine tuning may be performed with the control in the eighth exemplary embodiment in which the toner coat amount is measured. With the above, the toner coat amount may be corrected to a desired amount in a precise manner without causing any defects.
The configurations of the exemplary embodiments described above may be combined in any possible way.
The present disclosure is capable of stabilizing the adhesion amount of toner, serving as a developer, on the developing roller, serving as a developer carrying member.
While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2016-080140 filed Apr. 13, 2016 and No. 2016-080518 filed Apr. 13, 2016, which are hereby incorporated by reference herein in their entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-080140 | Apr 2016 | JP | national |
| 2016-080518 | Apr 2016 | JP | national |
