JP2010128082A - Developing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily adjust a toner concentration to a predetermined value without stopping a printing operation, while keeping constant the weight of developer in a developer storage container. <P>SOLUTION: The developing device includes: the developer storage container 11 that has a supply port 21 and a discharge port 22; a developer conveying means that has conveyance screws 12 and 13 for circulating developer in the developer storage container 11 while agitating it, and a discharge screw 14 having a vane helical in a reverse direction to the conveyance screws 12 and 13 used for discharging developer from the developer storage container 11; a conveying drive means for reciprocally moving the developer conveying means in its axial direction; developer weight detecting means 20 and 6 for detecting the weight of developer in the developer storage container 11; and a discharge control means 6 for controlling the drive of a conveyance drive means based on the weight of developer detected by the developer weight detecting means 20 and 6, thereby controlling the distance of the discharging screw 14 of the developer conveying means to the discharge port 22. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a developing device and an image forming apparatus.

  2. Description of the Related Art Conventionally, a so-called trickle type developing device in which a two-component developer including a toner and a carrier is supplied and discharged is known. In a trickle-type developing device, the developer weight varies greatly between immediately after replenishment with a developer having a high toner concentration and immediately after discharge of surplus developer as compared with a replenishment device that replenishes only toner. To do. For this reason, if the magnetic permeability of the carrier containing iron is detected by the magnetic permeability sensor and the developer weight is calculated based on the detection result, it is impossible to obtain an accurate developer weight.

  Therefore, in the invention described in Patent Document 1, the developer weight within the detection range by the magnetic sensor is periodically increased or decreased, the developer weight is calculated from a value depending on a value near the lower limit of the output waveform of the magnetic sensor, and output. By correcting this value from the amplitude of the waveform, an appropriate developer weight is calculated.

  In the invention described in Patent Document 2, the developer replenishment and discharge operations are performed by estimating the developer weight from the average value and amplitude of the detection signal from the toner density sensor and the detection signal from the image density sensor. ing.

JP 2005-31327 A JP 2006-3682 A

  However, in the invention described in Patent Document 1, the developer weight is calculated from a value depending on the value near the lower limit of the output waveform of the magnetic sensor. That is, the detection signal from the magnetic sensor is only corrected to accurately obtain the developer weight, and the developer weight itself varies. In this case, control of the toner density becomes very difficult, and good image quality cannot be maintained.

  In the invention described in Patent Document 2, an image density sensor is used to estimate the developer weight. For this reason, it is necessary to temporarily stop the printing operation in order to read the detection signal from the image density sensor.

  Accordingly, the present invention provides a developing device and an image forming apparatus that can easily adjust the toner concentration to a desired value without stopping the printing operation by keeping the weight of the developer in the developer container constant. The task is to do.

As a means for solving the above problems, the present invention provides:
Developing device
A replenishing port for replenishing a developer containing toner and a carrier; a developer containing container having a discharge port for discharging;
Developer replenishing means for replenishing the developer via the replenishment port to the developer container;
In order to circulate and move the developer accommodated in the developer accommodating container, a conveying screw composed of spiral blades formed on a rotating shaft, and to discharge the developer from the developer accommodating container, A developer conveying means provided on the rotating shaft, and having a discharge screw having blades wound in reverse to the conveying screw;
A transport driving means for reciprocating the developer transport means in the axial direction;
Developer weight detecting means for detecting the weight of the developer in the developer container;
A replenishment amount determination means for determining a replenishment amount of the developer by the developer replenishment means based on the developer weight detected by the developer weight detection means;
A discharge control means for controlling the distance of the discharge screw of the developer conveying means with respect to the discharge port by drivingly controlling the conveyance driving means based on the developer weight detected by the developer weight detecting means;
It is set as the structure provided with.

  With this configuration, if the developer weight detected by the developer weight detection means is large, the distance of the discharge screw to the discharge port is increased to facilitate the discharge of the developer, and conversely, the detected developer weight is small. For example, the distance between the discharge screw and the discharge port can be reduced to make it difficult to discharge the developer. As a result, it is possible to easily adjust the toner density while keeping the weight of the developer in the developer container constant.

The developer container includes a flow path limiting portion having a small flow path cross-sectional area in an area where the discharge screw reciprocates as compared to other areas,
It is preferable that the discharge screw has a partition blade capable of opening and closing the inlet of the flow path restriction portion.

  With this configuration, the developer discharge amount can be adjusted more accurately and the developer weight in the developer container can be maintained constant.

The developer conveying means comprises a screw provided with a spiral blade around a rotating shaft,
The developer weight detection means calculates the weight of the developer in the developer container based on the difference in amplitude between the magnetic permeability sensor for detecting the magnetic permeability of the developer and the signal waveform input from the magnetic permeability sensor. What is necessary is just to provide the weight estimation part estimated.

  With this configuration, when the developer is conveyed by rotating the screw, the weight of the developer in the detection range of the magnetic permeability sensor periodically varies, but depending on the difference in the weight of the developer in the developer container Since the amplitude of the detection signal in the magnetic permeability sensor fluctuates, the weight of the developer in the developer container can be estimated by the magnetic permeability sensor that can be used for detecting the toner concentration.

The developer conveying means comprises a screw provided with a spiral blade around a rotating shaft,
The developer weight detection means calculates the weight of the developer in the developer container based on the difference in the period of the signal waveform input from the permeability sensor and the permeability sensor. A weight estimation unit for estimation may be provided.

  With this configuration, when the developer is conveyed by rotating the screw, the weight of the developer in the detection range of the magnetic permeability sensor periodically varies, but depending on the difference in the weight of the developer in the developer container The torque required to rotate the screw fluctuates. As the developer weight increases, the screw load increases and the rotation cycle decreases. On the other hand, as the developer weight decreases, the screw load decreases and the rotation cycle increases. Therefore, the weight of the developer in the developer container is estimated by the permeability sensor that can be used to detect the toner concentration based on the change in the period of the detection waveform of the permeability sensor with the fluctuation of the rotation speed of the screw. It becomes possible to do.

  The developer weight detection means includes a pressure sensor that detects a pressure acting from the developer, and a weight estimation unit that estimates the weight of the developer in the developer container based on a detection signal input from the pressure sensor. May be provided.

  With this configuration, it is possible to estimate the weight of the developer in the developer container more accurately based on the detection signal of the pressure sensor that directly changes due to the difference in the weight of the developer in the developer container. It becomes.

  It is preferable that the weight estimation unit further corrects the weight of the developer in the developer container by taking into account the toner concentration calculated from the detection signal from the magnetic permeability sensor.

  With this configuration, the weight of the developer can be estimated more accurately in consideration of the change in the bulk density of the developer due to the difference in the detected toner concentration.

  Further, according to the present invention, as means for solving the above-described problems, an image forming apparatus includes any one of the developing devices.

  According to the present invention, the developer discharge amount is controlled by adjusting the position of the discharge screw with respect to the discharge port, so that the developer weight in the developer container is kept constant, and the toner concentration Can be easily adjusted. This makes it possible to form a good image.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings. In the following description, terms indicating specific directions and positions (for example, “up”, “down”, “side”, “end” and other terms including those terms) are used as necessary. These terms are used for easy understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of these terms.

(Constitution)
FIG. 1 shows a so-called trickle-type image forming apparatus in which a developer containing not only toner but also a small amount of carrier is replenished among electrophotographic systems using a two-component developer. The image forming apparatus generally includes an image forming unit 1, a transfer unit 2, an exposure unit 3, a paper feeding unit 4, a cleaning unit 5, a control unit 6 (see FIG. 6), and the like. However, the present invention is not only applied to this type of image forming apparatus 1, but can also be applied to, for example, a so-called four-cycle color image forming apparatus or a monochrome output image forming apparatus. Further, the present invention can also be applied to a copying machine, a printer, a facsimile machine, or a multi-function machine having a combination of these functions.

  The image forming unit 1 is arranged at four locations along the intermediate transfer belt 27 of the transfer unit 2 and performs image formation of yellow (Y), magenta (M), cyan (C), and black (Bk) from the left side, respectively. As a result, a color image is formed on the surface of the intermediate transfer belt 27. As shown in FIG. 2, each image forming unit 1 includes a charging device 8, a developing device 9, a cleaning device 10, and the like around the photosensitive drum 7.

  The charging device 8 forms a predetermined surface potential on the surface of the photosensitive drum 7. This surface potential becomes an electrostatic latent image when exposed by the exposure unit 3.

  As shown in FIGS. 2 and 3, the developing device 9 stores a stirring screw 12, a supply screw 13, a discharge screw 14, and a developing roller 15 in a developer container 11.

  As shown in FIG. 3, the developer storage container 11 has a long box shape extending from one end side to the other end side, and the interior is divided into a first storage portion 17 and a second storage along the longitudinal direction by a partition wall 16. It is divided into two parts. However, both end sides of the first storage portion 17 and the second storage portion 18 are communicated with each other by communication portions 19 a and 19 b, and the developer can be circulated and moved in the developer storage container 11.

  The first storage unit 17 is provided with a toner concentration sensor 20 as means for detecting the toner amount per unit volume. The toner concentration sensor 20 outputs a difference in magnetic permeability of the developer (iron contained in the carrier) as a frequency, and calculates a toner concentration (weight ratio of the toner to the developer) according to the graph shown in FIG. It is.

  A developer replenishing port 21 is formed on one end side of the first accommodating portion 17, and the developer is replenished from a corresponding developer replenishing container 25 as will be described later. Here, a two-component developer containing toner and carrier is used as the developer. However, an external additive or the like may be further included in the developer.

  A developer discharge port 22 is formed on one end side of the second storage portion 18 so that the carrier deteriorated by discharging the developer appropriately does not remain in the developer storage container 11 over a long period of time. Yes. In addition, a flow path restriction portion 41 having a smaller flow path cross-sectional area than the other areas of the second storage portion 18 is formed in a predetermined range up to the developer discharge port 22. The communication part 19b is formed at a position away from the inlet 41a of the flow path restriction part 41 by a predetermined dimension on the side opposite to the flow path restriction part 41.

  The stirring screw 12 is arranged in the first housing portion 17 with a configuration including a spiral blade 12b around the rotating shaft 12a. The agitation screw 12 is agitated while transporting the developer from one end side to the other end side by being rotationally driven. As a result, the developer weight in the detection range of the toner concentration sensor 20 fluctuates each time the stirring screw 12 rotates once, and the detection signal from the toner concentration sensor 20 has an output waveform shown in the graph of FIG. More specifically, as shown in FIG. 7A, the output of the toner concentration sensor 20 is such that the stirring screw 12 rotates and the developer weight within the detection range of the toner concentration sensor 20 becomes the maximum amount. As a result, the output becomes the minimum value. Conversely, as shown in FIG. 7B, the output becomes the maximum value when the developer weight in the detection range becomes the minimum amount.

  As shown in FIGS. 4 and 5, the supply screw 13 and the discharge screw 14 are formed on the same rotation shaft 40, arranged in the second housing portion 18, and can reciprocate in the axial direction. The supply screw 13 is driven to rotate, thereby transferring the developer from the communication portion 19 b side to the communication portion 19 a side and supplying the developer to the developing roller 15. The discharge screw 14 and a part of the supply screw 13 adjacent to the discharge screw 14 are formed so that the outer diameter of the blade is smaller than that of the other part of the supply screw 13. It is possible to reciprocate within the path restriction unit 41. Further, the discharge screw 14 includes a reverse winding blade 42 and a forward winding blade 43. A partition blade 44 having a larger diameter than both blades is provided at the boundary position between both blades, and the inlet 41a of the flow path restricting portion 41 can be opened and closed. Further, the reverse winding blade 42 is formed to have a smaller pitch than the forward winding blade 43. The reverse winding portion 42 of the discharge screw 14 is disposed so as to be able to reciprocate in an adjustment region between the communication portion 19 and the inlet 41 a of the flow path restriction portion 41. Further, the small-diameter blade 13 </ b> A of the supply screw 13 is disposed so as to be able to reciprocate in the vicinity of the communication portion 19.

  The agitation screw 12 and the supply screw 13 are synchronized with each other by gears 12c and 13c provided at the ends of the rotary shafts 12a and 13a protruding from the developer container 11 and driven by a motor (not shown). And is designed to rotate.

  As shown in FIG. 2, the developing roller 15 has a plurality of permanent magnets 24 accommodated in a cylindrical sleeve 23 (here, five permanent magnets S2, N2, S1, N1, and S3 are connected to the developing roller 15). In order and clockwise.) The sleeve 23 is configured to rotate in the direction of the arrow in the figure by a sleeve driving means (not shown).

  Above the developing device 9, as shown in FIG. 1, a developer replenishing container 25 for replenishing a replenishing two-component developer (hereinafter simply referred to as a developer) composed of toner and carrier is detachable. ing. The developer concentration stored in the developer container 11 in advance is 7%, and the developer concentration supplied from the developer supply container 25 is 80% (carrier concentration is 20%, usually 10-20%). is there.

  After the transfer to the surface of the photosensitive drum 7, the cleaning device 10 collects the toner remaining on the surface and cleans it.

  The transfer unit 2 spans an intermediate transfer belt 27 between a pair of support rollers 26, drives the support roller 26 by a driving means (not shown), and circulates the intermediate transfer belt 27 in an arrow direction. A transfer unit 28 and a secondary transfer unit 29 are provided.

  The exposure unit 3 irradiates the photosensitive drum 7 with laser light to form an electrostatic latent image corresponding to image data read by a scanner (not shown).

  The paper feeding unit 4 sequentially conveys the recording medium 31 stored in the cassette 30 to the secondary transfer unit 29 via the conveyance roller 32. A toner image is transferred to the recording medium 31 conveyed to the secondary transfer unit 29, and the toner image transferred by the fixing unit 33 is fixed, and then is carried out to the discharge tray 34.

  The cleaning unit 5 can come into contact with and separate from the intermediate transfer belt 27, and collects and cleans toner remaining on the intermediate transfer belt 27 when approaching.

  The control unit 6 executes a developer replenishment process based on the detection voltage input from the toner density sensor 20 as described later.

(Operation)
Next, the operation of the image forming apparatus having the above configuration will be described.

  At the time of image formation, color print data obtained by reading an image or image data output from a personal computer or the like is subjected to predetermined signal processing, and then yellow (Y), magenta (M), cyan (C ) And black (Bk) image signals of each color are transmitted to each image forming unit 1.

  In each image forming unit 1, a laser beam modulated by an image signal is projected onto each photosensitive drum 7 to form an image latent image. Then, toner is supplied from the developing device 9 to the photosensitive drum 7.

  In the developing device 9, the developer stored in the developer container 11 is circulated while being stirred by rotationally driving the stirring screw 12 and the supply screw 13. Then, toner is supplied from the supply screw 13 to the developing roller 15, scraped off by the regulating member 11 a, and then transported to the photosensitive drum 7.

  As a result, yellow, magenta, cyan, and black toner images are formed on the respective photosensitive drums 7. The formed yellow, magenta, cyan, and black toner images are primary-transferred by the primary transfer unit 28 while sequentially superposed on the moving intermediate transfer belt 27. The superimposed toner image formed on the intermediate transfer belt 27 in this way moves to the secondary transfer unit 29 as the intermediate transfer belt 27 moves.

  A recording medium 31 is supplied from the paper supply unit 4. The supplied recording medium 31 is conveyed between the secondary transfer unit 29 and the intermediate transfer belt 27 by the conveyance roller 32, and the toner image formed on the intermediate transfer belt 27 is transferred. The recording medium 31 to which the toner image has been transferred is further conveyed to the fixing unit 33, where the transferred toner image is fixed and then discharged to the discharge tray 34.

  By the way, in the developing device 9, the developer replenishing process is performed by estimating the weight of the developer stored in the developer storage container 11 and adjusting the discharge amount as follows according to the flowchart shown in FIG. To do.

(Method for estimating developer weight)
When the printing process is started (step S1), a detection signal from the toner concentration sensor 20 is read while the stirring screw 12 and the supply screw 13 are rotated in synchronization (step S2). The read detection signal has a ripple waveform as shown in the graph of FIG. As shown in FIGS. 9 (a) and 9 (b), the detected magnetic permeability is periodically changed with the fluctuation of the developer weight within the detection range of the toner concentration sensor 20 by the rotation of the stirring screw 12. Because it changes to.

  Therefore, based on the detected value in the state shown in FIG. 9B in which the developer weight in the detection range becomes the minimum value, the toner density is calculated according to the graph of FIG. 7 (step S3). Based on the detection signal from the toner density sensor 20, the detected value in the state shown in FIG. 9A in which the developer weight in the detection range reaches the maximum value, and the developer weight in the detection range is the minimum. The amplitude (maximum amplitude) of the signal waveform is calculated from the detected value in the state shown in FIG. 9B, which is a value (step S4).

  Subsequently, the developer weight is estimated according to the data table shown in FIG. 12 based on the calculated amplitude and the toner concentration detected by the toner concentration sensor 20 (step S5). That is, it is determined that the smaller the amplitude, the greater the developer weight. This is because if the developer weight in the developer container 11 is large, even if the stirring screw 12 is rotated, the developer weight within the detection range of the toner concentration sensor 20 does not change so much and the magnetic permeability is low. It is because it is thought that it does not change so much. Further, it is determined that the larger the amplitude, the smaller the developer weight. This is because if the developer weight in the developer container 11 is small, the developer weight within the detection range is likely to change due to the rotation of the stirring screw 12, and the magnetic permeability is considered to vary greatly. Furthermore, it is determined that the lower the toner concentration, the greater the developer weight. This is because if the developer weight in the developer container 11 is large, carriers contained in the developer tend to gather in the detection range of the toner concentration sensor 20, and the toner concentration in the detection range becomes relatively low. is there. Furthermore, it is determined that the higher the toner concentration, the smaller the developer weight. This is because it is considered that when the developer weight in the developer container 11 is small, the developer is sufficiently stirred and the toner concentration becomes relatively high. Here, the estimation of the developer weight is performed in five stages: small weight 2, small weight 1, appropriate, large weight 1, and heavy weight 2.

  Further, the developer replenishment amount is calculated based on the difference between the toner density detected by the toner density sensor 20 and the target toner density stored in advance (step S6). Then, a replenishment process of a replenishment amount calculated from the developer replenishment container 25 is started (step S7).

(Emission adjustment method)
Thereafter, when the printing process is completed (step S8), the movement dimensions of the supply screw 13 and the discharge screw 14 (from the reference position of the partition blade 44) are determined according to the estimated developer weight level according to the data table of FIG. Determine (step S9).

  Here, the axial length of the adjustment region is 14 mm, and the reference position of the partition blade 44 in the adjustment region is 3 mm from the inlet of the flow path restriction unit 41. Further, the partition blade 44 is set at a reference position shown in FIG. 4A if it is an appropriate amount, and the small-diameter blade 13A of the supply screw 13 is positioned at a position facing the communication portion 19. Moreover, by deviating from an appropriate amount, the partition blade 44 is moved as follows according to the degree of detachment. If the estimation result is a small weight 2, the partition blade 44 is moved from the reference position to a position of 5 mm (+5 mm) on the right side as shown in FIG. Close (almost) the entrance. Thereby, the discharge of the developer from the developer discharge port 22 is prevented, and the developer weight in the developer storage container 11 can be quickly returned to the standard value by the supplied developer. If the estimated result is a small weight 1, as shown in FIG. 4B, the position of 2.5 mm (+2.5 mm) is set on the right side to suppress the developer discharge amount. Further, if the estimated result is a large weight 1, as shown in FIG. 5A, the position is set to 2.5 mm (−2.5 mm) on the left side so that the developer can be easily discharged from the developer discharge port 22. . Furthermore, if the estimation result is a large weight 2, as shown in FIG. 5B, the left side is set to a position of 5 mm (−5 mm), and the discharge screw 14 is moved to the boundary position between the communication portion 19 and the adjustment region. The developer is most likely to flow into the flow path restriction portion 41.

  Thus, according to the embodiment, the weight of the developer in the developer container 11 is estimated, and the replenishment and discharge of the developer are controlled based on the estimated result and the detected toner concentration. I have to. Therefore, it is possible to appropriately adjust the toner density while keeping the developer weight in the developer container 11 constant, and good image formation is possible.

(Other embodiments)
The present invention is not limited to the configuration described in the embodiment, and various modifications can be made. In the following description, the description of the same configuration as that of the above embodiment is omitted, and the same members are denoted by the same reference numerals even in the illustrated members, and the description thereof is omitted.

  In the above-described embodiment, the developer weight in the developer container 11 is estimated based on the amplitude of the signal waveform input from the toner concentration sensor 20 and the toner concentration, but is estimated as follows. Is also possible.

  For example, the developer weight in the developer container 11 may be estimated according to the data table of FIG. 13 based on the period of the signal waveform input from the toner concentration sensor 20 and the toner concentration. That is, when the developer weight in the developer container 11 increases, the load acting on the discharge screw 14 increases and the rotation speed decreases. For this reason, the period of the signal waveform output from the toner density sensor 20 becomes longer. On the other hand, when the developer weight in the developer container 11 is reduced, the load acting on the discharge screw 14 is reduced and the rotation speed is increased. For this reason, the cycle of the signal waveform output from the toner density sensor 20 is shortened. Therefore, the developer weight in the developer container 11 may be estimated from the difference in the period of the signal waveform and the detected toner density according to the data table of FIG.

  In addition to the toner concentration sensor 20, a pressure sensor 35 (see a two-dot chain line in FIG. 3) is provided, and the pressure sensor 35 detects the pressure directly received from the developer in the developer container 11, and the detection result. Based on the toner density, the developer weight in the developer container 11 may be estimated according to the data table of FIG.

  In each of the embodiments described above, the developer weight is estimated from the amplitude or period of the signal waveform input from the toner concentration sensor 20 and the toner concentration. Alternatively, it may be estimated from only the amplitude, only the period, or only the pressure.

  The developer weight level estimated in each of the above embodiments is not limited to five levels, and may be three or four levels, or six or more levels as necessary, and may be stepless depending on circumstances.

  4 and 5, the supply screw 13 and the discharge screw 14 are configured to rotate coaxially. However, the supply screw 13 and the discharge screw 14 may be separately driven. In this case, first, the discharge screw 14 is moved in the axial direction, and if the developer weight in the developer container 11 cannot be adjusted to an appropriate amount within a predetermined time, the rotational speed of the discharge screw 14 is changed. do it. Conversely, if the rotation speed of the discharge screw 14 is changed and the developer weight in the developer container 11 cannot be adjusted to an appropriate amount within a predetermined time, the discharge screw 14 is moved in the axial direction. Also good. Of course, the rotational speed of the discharge screw 14 and the movement in the axial direction may be performed simultaneously. In short, what is necessary is just to control so that the developer weight in the developer container 11 is maintained constant.

1 is a schematic view of an image forming apparatus according to an embodiment. FIG. 2 is a transverse sectional view showing the developing device of FIG. 1. FIG. 2 is a longitudinal sectional view showing the developing device of FIG. 1. FIG. 2 is a partial cross-sectional view showing the developing device of FIG. 1. FIG. 2 is a partial cross-sectional view showing the developing device of FIG. 1. 1 is a block diagram of an image forming apparatus according to an embodiment. 6 is a graph showing a relationship between an output of a toner density sensor and a toner density. It is a graph which shows the change of the output value of a toner concentration sensor accompanying rotation of a stirring screw. FIG. 6 is a cross-sectional view illustrating a state of a developer accompanying rotation of a stirring screw in the vicinity of a toner concentration sensor. It is a data table for determining the position which moves a partition blade according to the level of the estimated developer weight. 3 is a flowchart showing control contents in the developing device of FIG. 1. 6 is a data table for estimating the developer weight in the developer container based on the amplitude of the signal waveform detected by the toner concentration sensor and the toner concentration. 6 is a data table for estimating the developer weight in the developer container based on the period of the signal waveform detected by the toner concentration sensor and the toner concentration. It is a data table for estimating the developer weight in a developer storage container based on the detection result in a pressure sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image formation unit 2 ... Transfer unit 3 ... Exposure unit 4 ... Paper feed unit 5 ... Cleaning unit 6 ... Control unit (Developer weight detection means, supply amount determination means)
DESCRIPTION OF SYMBOLS 7 ... Photosensitive drum 8 ... Charging device 9 ... Developing device 10 ... Cleaning device 11 ... Developer container 12 ... Stirring screw (conveying screw, developer conveying means)
13 ... Supply screw (conveying screw, developer conveying means)
14 ... discharge screw (discharge screw, developer discharge means)
DESCRIPTION OF SYMBOLS 15 ... Developing roller 16 ... Partition wall 17 ... 1st accommodating part 18 ... 2nd accommodating part 19a, 19b, 19c ... Communication part 20 ... Toner density sensor 21 ... Developer supply port 22 ... Developer discharge port 23 ... Sleeve 24 ... Permanent magnet 25 ... developer supply container (developer supply means)
DESCRIPTION OF SYMBOLS 26 ... Support roller 27 ... Intermediate transfer belt 28 ... Primary transfer part 29 ... Secondary transfer part 30 ... Cassette 31 ... Recording medium 32 ... Conveyance roller 33 ... Fixing unit 34 ... Discharge tray 35 ... Pressure sensor 40 ... Rotating shaft 41 ... Channel restricting part 42 ... Reverse winding part 43 ... Forward winding part 44 ... Partition blade

Claims (7)

A replenishing port for replenishing a developer containing toner and a carrier; a developer containing container having a discharge port for discharging;
Developer replenishing means for replenishing the developer via the replenishment port to the developer container;
In order to circulate and move the developer accommodated in the developer accommodating container, a conveying screw composed of spiral blades formed on a rotating shaft, and to discharge the developer from the developer accommodating container, A developer conveying means provided on the rotating shaft, and having a discharge screw having blades wound in reverse to the conveying screw;
A transport driving means for reciprocating the developer transport means in the axial direction;
Developer weight detecting means for detecting the weight of the developer in the developer container;
A replenishment amount determination means for determining a replenishment amount of the developer by the developer replenishment means based on the developer weight detected by the developer weight detection means;
A discharge control means for controlling the distance of the discharge screw of the developer conveying means with respect to the discharge port by drivingly controlling the conveyance driving means based on the developer weight detected by the developer weight detecting means;
A developing device comprising: The developer container includes a flow path limiting portion having a small flow path cross-sectional area in an area where the discharge screw reciprocates as compared to other areas,
The developing device according to claim 1, wherein the discharge screw has a partition blade capable of opening and closing an inlet of the flow path restriction unit.   The developer weight detection means calculates the weight of the developer in the developer container based on the difference in amplitude between the magnetic permeability sensor for detecting the magnetic permeability of the developer and the signal waveform input from the magnetic permeability sensor. The developing device according to claim 1, further comprising a weight estimating unit that estimates the weight.   The developer weight detection means calculates the weight of the developer in the developer container based on the difference in the period of the signal waveform input from the permeability sensor and the permeability sensor. The developing device according to claim 1, further comprising a weight estimating unit that estimates the weight.   The developer weight detection means includes a pressure sensor that detects a pressure acting from the developer, and a weight estimation unit that estimates the weight of the developer in the developer container based on a detection signal input from the pressure sensor. The developing device according to claim 1, further comprising:   6. The weight estimation unit further corrects the weight of the developer in the developer container taking into account the toner concentration calculated from the detection signal from the magnetic permeability sensor. The developing device according to claim 1.   An image forming apparatus comprising the developing device according to claim 1.

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