Patent Application
20100239273
This application is based on Japanese Patent Application No. 2009-067829 filed in Japan on Mar. 19, 2009, the entire content of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a DEVELOPING APPARATUS and an image forming apparatus.
2. Description of the Related Art
Conventionally, in a so-called trickle type image forming apparatus structured such as to discharge a developer including a deteriorated carrier, and replenish a new developer, for example, the following structure is known.
In other words, in Japanese Unexamined Patent Publication No. 2008-250290, there is disclosed a structure which is provided with an inflow portion making a developer flow from a first accommodating chamber to a second accommodating chamber. The inflow portion is constructed by opening portions (a first opening portion and a second opening portion) at two positions. The first opening portion is arranged in the vicinity of an upstream side of an inverse winding blade of a first feeding member provided in the first accommodating chamber, and the second opening portion is formed in a downstream side thereof. Further, a discharge portion for discharging the developer is formed in the middle of the inverse winding blade, and a replenishing portion for replenishing the developer is formed within the first accommodating chamber in the vicinity of the downstream side thereof.
However, in the DEVELOPING APPARATUS described in the Japanese Unexamined Patent Publication No. 2008-250290 mentioned above, the replenishing portion of the developer is arranged within the first accommodating chamber, and is positioned in the vicinity of the discharge portion. Accordingly, if an amount of the replenished developer is much, there is a problem that the developer is discharged from the discharge portion in spite that it is not deteriorated. Further, since the discharge portion is provided in a region in which the inverse winding blade is arranged, that is, a region in which the developer is apt to stay, there is the danger that the developer is discharged from the discharge portion more than necessary.
Accordingly, an object of the present invention is to provide a DEVELOPING APPARATUS and an image forming apparatus which can prevent a developer from being discharged more than necessary, and can maintain an amount of the developer in an inner portion at an appropriate value so as to obtain a desired toner density.
The present invention adopts a following configuration as means to solve above described problem:
a DEVELOPING APPARATUS including:
a developer carrying member;
a developer accommodating container extending from one end to the other end along the developer carrying member, and in which the developer is accommodated;
a first feeding member provided within the developer accommodating container and feeding the accommodated developer while agitating; and
a second feeding member provided within the developer accommodating container and feeding the developer to the developer carrying member,
wherein the developer accommodating container includes:
a first accommodating portion in which the first feeding member is arranged;
a second accommodating portion in which the second feeding member is arranged;
a first communication portion communicating the first accommodating portion and the second accommodating portion in one end side;
a second communication portion and a third communication portion communicating the first accommodating portion and the second accommodating portion at two positions in the other end side so as to be shifted their positions in a feeding direction of the developer;
a discharge portion arranged between the second communication portion and the third communication portion in the second accommodating portion, and provided for discharging the developer; and
a replenishing portion arranged in a downstream side in the feeding direction of the developer than the third communication portion, in the first accommodating portion, and provided for replenishing the developer.
In accordance with this structure, the developer is fed to the second communication portion side and the third communication portion side by the second feeding member in the second accommodating portion. The developer fed to the third communication portion side is partly discharged via the discharge portion, and thereafter flows to the first accommodating portion via the third communication portion. In the first accommodating portion, the new developer is replenished via the replenishing portion, and is mixed with the developer flowing via the third communication portion so as to be fed. As mentioned above, since the replenishing portion is provided in the first accommodating portion side in place of the second accommodating portion provided with the discharge portion, the replenished developer is not discharged from the discharge portion. Accordingly, it is possible to appropriately regulate the toner density within the developer accommodating container.
It is preferable that the replenishing portion is arranged between the second communication portion and the third communication portion.
In accordance with this structure, the new developer replenished via the replenishing portion is first of all mixed with the remainder of the developer which is discharged by the discharge portion so as to be reduced. Therefore, it is possible to smoothly replenish the developer from the replenishing portion. Further, the remainder of the developer and the newly replenished developer are mixed with the developer which circulates via the second communication portion. Accordingly, a fluctuation of the toner density of the developer is small, and it is possible to obtain a good condition all over a whole of the developer accommodating container.
It is preferable that a conveyance inhibiting portion preventing the conveyance of the developer is provided in the vicinity of an upstream side in a feeding direction of the developer, with respect to the discharge portion.
In accordance with this structure, only the surplus developer running over the conveyance inhibiting portion is fed to the discharge portion. In the discharge portion, after a part of the developer is discharged, the remainder is fed as it is so as to flow to the first accommodating portion via the third communication portion. Accordingly, it is possible to prevent such a problem that the discharging amount in the discharge portion becomes more than necessary from being generated.
It is preferable that an opening degree regulating member for regulating an opening degree of the discharge portion is provided.
In accordance with this structure, in the case that it is not necessary to discharge the developer, it is possible to make the opening degree of the discharge portion small by the opening degree regulating member, or close the discharge portion. The developer passing through the discharge portion flows to the first accommodating portion via the third communication portion, and flows together with the developer circulating via the second communication portion so as to keep up with the circulating movement. Therefore, since it is possible to feed the developer in all the regions within the developer accommodating container, the developer does not stay. Accordingly, it is possible to prevent such a problem that the feeding member is exposed to an unreasonable load so as to be damaged from being generated.
It is preferable that a developer weight presuming member for presuming a weight of the developer within the developer accommodating container; and
an opening degree controller regulating an opening degree of the discharge portion by controlling to drive the opening degree regulating member on the basis of the weight of the developer which is presumed by the developer weight presuming member are further provided.
In accordance with this structure, it is possible to set the weight of the developer discharged via the discharge portion to an appropriate value on the basis of the weight of the developer within the developer accommodating container.
Further, in accordance with the present invention, there is provided an image forming apparatus which is provided with the DEVELOPING APPARATUS described in any one of the aspects mentioned above, as a means for solving the problem mentioned above.
In accordance with the present invention, since the discharge portion is provided at the position within the second accommodating portion running over the second communication portion, and the replenishing portion is provided at the position within the first accommodating portion running over the third communication portion, it is possible to prevent such a problem that the developer replenished from the replenishing portion is directly discharged from the discharge portion from being generated. Therefore, it is possible to appropriately regulate the toner density within the developer accommodating container.
A description will be given below of an embodiment in accordance with the present invention with reference to the accompanying drawings. In this case, in the following description, terms (for example, terms including “upper”, “lower”, “side” and “end”) indicating specific directions and positions are used as occasion demands, however, these terms are used for facilitating the understanding of the invention with reference to the drawings, and a technical range of the present invention is not limited by the meanings of the terms.
The image forming units 1 are arranged at four positions along an intermediate transfer belt 44 of the transfer unit 2, and form a color image on a surface of the intermediate transfer belt 44 by respectively carrying out an image formation of yellow (Y), magenta (M), cyan (C) and black (Bk) from a left side. Each of the image forming units 1 is provided with a charging apparatus 9, a DEVELOPING APPARATUS 10, a cleaning apparatus 11 and the like around a photoreceptor drum 8, as shown in
The charging apparatus 9 forms a predetermined surface potential on a surface of the photoreceptor drum 8. The surface potential comes to an electrostatic latent image by being exposed by the exposure unit 3. In this case, a non-contact type scorotron charger is used as the charging apparatus 9, however, it is possible to use, for example, a contact type such as a blade-shaped, a brush-shaped, and the like, and it is possible to use a charging roller.
The DEVELOPING APPARATUS 10 is structured, as shown in
The developer accommodating container 12 is formed as a long box shape extending from one end side to the other end side, as shown in
The first accommodating portion 20 is provided with a toner density sensor 29 as a means for detecting a toner amount per unit volume. The toner density sensor 29 is a conventionally well-known sensor which outputs a difference of magnetic permeability of the developer (an iron content included in a carrier) as a frequency, and computes a toner density (a weight rate of the toner with respect to the developer).
Further, a developer replenishing port 30 is formed between the second communication portion 23 and the third communication portion 24, in a part (a portion constructed by the tubular portion 17) of the first accommodating portion 20. Further, the structure is made such that a new developer is appropriately replenished from a developer replenishing container 42 via the developer replenishing port 30.
A developer discharge port 31 is formed between the second communication portion 23 and the third communication portion 24, as shown in
The agitating screw 13 is structured, as shown in
The feeding screw 14 is structured, as shown in
The developing roller 15 is structured, as shown in
A developer replenishing container 42 replenishing a replenishing two-component developer (hereinafter, described simply as a developer) constructed by a toner and a carrier is detachably provided, as shown in
The cleaning apparatus 11 recovers the toner staying in the surface of the photoreceptor drum 8 after being transferred to the surface so as to clean, as shown in
The transfer unit 2 is structured, as shown in
The exposure unit 3 irradiates a laser light to the photoreceptor drum 8, as shown in
The fixing unit 4 is structured such as to rotatably support a fixing roller and a pressurizing roller, although not being illustrated. The fixing roller is made of a conductive material, is rotatably driven by a motor (not shown), and is induction heated by an exciting coil (not shown). The pressurizing roller is brought into pressure contact with the fixing roller, and pinches a recording medium 48. Accordingly, it is possible to fix the toner transferred by the transfer unit 2 to the recording medium 48.
The paper feeding unit 5 feeds the recording medium 48 accommodated in a cassette 47 to the secondary transfer portion 46 via a feed roller 49 sequentially, as shown in
The cleaning unit 6 can come close to and away from the intermediate transfer belt 44, and recovers the toner staying in the intermediate transfer belt 44 so as to clean by coming close thereto.
The control unit 7 executes an image forming process on the basis of an input signal as shown in
Next, a description will be given of a motion of the image forming apparatus having the structure mentioned above.
At a time of forming the image, a color print data obtained by reading the image or an image data output from a personal computer or the like is applied to a predetermined signal process, and is thereafter transmitted as an image signal of each of the colors including yellow (Y), magenta (M), cyan (C) and black (Bk) to each of the image forming units 1.
In each of the image forming units 1, an image latent image is formed by projecting a laser light which is modulated by the image signal onto the photoreceptor drum 8. Further, the toner is fed to the photoreceptor drum 8 from the DEVELOPING APPARATUS 10.
In the DEVELOPING APPARATUS 10, a developing process is carried out in accordance with the following manner. In other words, the developer accommodated within the developer accommodating container 12 is circulated while being agitated, by rotatably driving the agitating screw 13 and the feeding screw 14. Further, the toner is fed from the feeding screw 14 to the developing roller 15, is scraped off by the regulating member 12a so as to be set to a fixed amount, and is thereafter fed to the photoreceptor drum 8. In this case, details of the developing process will be mentioned later.
Accordingly, the toner images of yellow, magenta, cyan and black are formed respectively on each of the photoreceptor drum 8. The formed toner images of yellow, magenta, cyan and black are sequentially overlapped on the moving intermediate transfer belt 44 so as to be primarily transferred. The overlapping toner image formed on the intermediate transfer belt 44 as mentioned above is moved to the secondary transfer portion 46 in accordance with a movement of the intermediate transfer belt 44.
Further, the recording medium 48 is fed from the paper feeding unit 5. The fed recording medium 48 is fed to a portion between the secondary transfer portion 46 and the intermediate transfer belt 44 by the feed roller 49, and the toner image formed in the intermediate transfer belt 44 is transferred thereto. The recording medium 48 to which the toner image is transferred is further fed to the fixing unit 4, where the transferred toner image is fixed, and is thereafter discharged to the discharge tray 50.
In the developing process, the developer accommodated within the developer accommodating container 12 is moved in a circulating manner while being agitated, by rotatably driving the agitating screw 13 and the feeding screw 14. In this process, the toner is fed to the developing roller 15 by the feeding screw 14.
In other words, in the second accommodating portion 21, the developer is fed from the first communication portion 22 side to the second communication portion 23 side while being agitated by the first blade portion 37 of the feeding screw 14, and is fed to the developing roller 15. If the developer runs into the vicinity of the second communication portion 23, the developer is exposed to a flow resistance by the inverse wound second blade portion 38. Accordingly, the developer mainly flows into the first accommodating portion 20 via the second communication portion 23. Further, a part of the developer (the surplus developer) gets over the second blade portion 38 so as to flow into the inflow regulation region 25. The third blade portion 39 is provided at a position getting over the second blade portion 38, and the developer is agitated and flows again in a forward direction. Further, the developer discharge port 31 is formed in the middle of the flowing region by this third blade portion 39. Accordingly, a feeding speed of the developer is not lowered in the vicinity of the developer discharge port 31, and an amount of the developer discharged via the developer discharge port 31 does not become more than necessary. The developer which is not discharged from the developer discharge port 31 flows into the first accommodating portion 20 via the third communication portion 24. In this case, the developer discharge port 31 is regulated its opening degree by the opening degree regulating plate 32 on the basis of a difference of developing process condition, as mentioned below.
In the first accommodating portion 20, a fact that the toner is consumed is detected by the toner density sensor 29, and the developer is appropriately replenished from the developer replenishing container 42 to the developer accommodating container 12 on the basis of the detection signal. The developer is replenished via the developer replenishing port 30 formed in the first accommodating portion 20. The developer replenishing port 30 is formed between the second communication portion 23 and the third communication portion 24, and is positioned in a downstream side of the third communication portion 24 with respect to a circulating and moving direction of the developer. Accordingly, the developer flows while being agitated together with the developer flowing via the third communication portion 24 without being discharged from the developer discharge port 31, and flows together with the developer circulating and moving via the second communication portion 23. Accordingly, it is possible to smoothly mix with reason the replenished new developer and the circulating and moving developer, and it is possible to inhibit a dispersion of the toner density from being generated. Further, the replenished developer does not run into the developer discharge port 31 as is different from the prior art.
The opening and closing motion of the opening degree regulating plate 32 may be controlled, for example, in accordance with the following manner.
In other words, the opening degree of the developer discharge port 31 is regulated by presuming a weight of the developer within the developer accommodating container 12 on the basis of the detection signal by the toner density sensor 29, and deciding the open position by the opening degree regulating plate 32 on the basis of a difference of presumed amount of the developer.
In the presumption of the amount of the developer within the developer accommodating container 12, as shown in
Accordingly, the step calculates the toner density in accordance with a graph in
Subsequently, the step presumes the weight of the developer in accordance with a data table shown in
Further, the step calculates a replenishing amount of the developer on the basis of a difference between the detected toner density by the toner density sensor 29 and a previously stored target toner density (a step S6). Further, the step starts a replenishing process for replenishing the calculated replenishing amount of developer from the developer replenishing container 42 (a step S7).
Thereafter, if the replenishing process is finished (a step S8), the step regulates the opening degree of the developer discharge port 31 by controlling to drive the opening degree regulating plate 32 in correspondence to a level of the presumed weight of the developer (a step S9). In this case, since the weight of the developer is presumed by five stages, the opening degree is structured such as to be regulated by five stages including a case that the developer discharge port 31 is fully opened by the opening degree regulating plate 32, and a case that it is fully closed.
In the meantime, even if the opening degree of the developer discharge port 31 becomes small (is closed in some cases), the developer smoothly flows from the second accommodating portion 21 to the first accommodating portion 20 via the third communication portion 24. Therefore, since there is no case that the unreasonable load is applied to the feeding screw 14 and the driving torque is increased, no damage is generated.
In this case, the present invention is not limited to the structure described in the embodiment mentioned above, but can be variously modified.
For example, in the embodiment mentioned above, the developer replenishing port 30 is structured such as to be arranged between the second communication portion 23 and the third communication portion 24, however, may be arranged at any position as far as a position within the first accommodating portion 20. In some cases, the developer replenishing port 30 may be arranged in an upstream side (between the first communication portion 22 and the second communication portion 23) of the second accommodating portion 21. In this case, it is possible to make the mixed state of the developer good so as to prevent a dispersion of the toner density from being generated, as mentioned above, by arranging the developer replenishing port 30 between the second communication portion 23 and the third communication portion 24.
Further, the embodiment mentioned above is structured such that the opening degree of the developer discharge port 31 is regulated by the opening degree regulating plate 32, however, the other structure such as a lens diaphragm may be employed.
Further, in the embodiment mentioned above, the feeding screw 14 is structured such that the first blade portion 37, the second blade portion 38 and the third blade portion 39 are formed in the feeding side rotating shaft 35, however, they may be independently driven, or the first blade portion 37 may be driven independently from the second blade portion 38 and the third blade portion 39. In this case, it is possible to regulate an inflow amount of the developer into the inflow regulation region 25 regardless of a feeding capacity of the developer by the first blade portion 37, by controlling the rotating speed of the second blade portion 38 (in some cases, the opening degree regulating plate 32 may be unnecessary).
Further, in the embodiment mentioned above, the weight of the developer within the developer accommodating container 12 is presumed on the basis of the amplitude of the signal wave form input from the toner density sensor 29 and the toner density, however, may be presumed in the following manner.
For example, the weight of the developer within the developer accommodating container 12 may be presumed in accordance with a data table in
Further, the structure may be made such that a pressure sensor (not shown) is provided in addition to the toner density sensor 29, a pressure directly applied from the developer within the developer accommodating container 12 is detected by the pressure sensor, and the weight of the developer within the developer accommodating container 12 is presumed in accordance with a data table in
Further, each of the embodiments mentioned above is structured such that the weight of the developer is presumed on the basis of the amplitude or the cycle of the signal wave form input from the toner density sensor 29, and the toner density, however, the weight of the developer may be presumed only from the amplitude of the signal wave form, only from the cycle or only from the pressure, although a precision is somewhat low.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-067829 | Mar 2009 | JP | national |
