JP2013020014A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device in which variations in the amount of developer discharge caused by the inclination of a developing container is restrained and the occurrence of developer overflow is suppressed.SOLUTION: An image forming apparatus includes a developing device comprising a developing container 41 for containing developer and stirring conveyance members 42, 43, 48b for stirring and conveying the developer in the developing container 41, and the developing container 41 has a developer discharge port 48a for discharging the developer outside. Also, there are included an inclination angle detection sensor 600 for detecting an inclination of the developing container 41 and toner consumption calculation means for calculating the consumption of toner used for developing. If it is determined, using the inclination angle detection sensor 600, that the developing container is inclined in such a direction as to face the developer discharge port 48a downward, replenishment with the developer is carried out from a hopper. If it is determined, using the inclination angle detection sensor 600, that the developing container is inclined in such a direction as to face the developer discharge port 48a upward, a rotational speed of screws 42, 43, 48b is increased.

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, and a FAX.

  Conventional image forming apparatuses have been proposed in which deterioration of charging performance can be suppressed by supplying developer to the developing apparatus. As this type of apparatus, an ACR configuration as in Patent Document 1 has been proposed. In this configuration, a new developer replenishing device is provided in the developing device, and the developer in the developing device that has become excessive due to the replenishment of new developer by the replenishing device is removed by the developer discharge provided on the wall surface of the developing device. Overflow from the outlet, discharge and collect.

  In such an apparatus, replenishment of new developer and discharge of developer are sequentially repeated, whereby the deteriorated developer in the developing apparatus is replaced with newly supplied toner and carrier. As a result, it is possible to maintain the development characteristics and charging characteristics of the developer in the developing device, and to suppress deterioration in image quality. Further, the developer replacement frequency can be reduced.

  Further, in a developing device having an ACR configuration using a two-component developer, when the developer container is inclined and the developer is excessively discharged and the developer becomes less than a predetermined amount, longitudinal density unevenness, screw pitch unevenness, etc. An image defect occurs. On the other hand, when the developer container is inclined to make it difficult for the developer to be discharged and the developer becomes larger than a predetermined amount, screw lock and developer overflow occur. In order to prevent the developer discharge amount in the developing container from fluctuating due to such inclination of the developing container, configurations such as Patent Documents 2 and 3 have been proposed.

  In Patent Document 2, the transport amount per unit time of the developer transport member in the reservoir in the vicinity of the discharge port is made smaller than other portions. This prevents the developer from being excessively discharged even when the developing container is inclined.

  In Patent Document 3, a plurality of strip-shaped electrodes arranged in parallel are provided, a traveling wave electric field that selectively transports carriers is generated, and the carriers are transported to the discharge port.

JP 59-1000047 A JP 2009-192701 A JP 2007-322970 A

  However, in Patent Document 2, the developer flowing from the clearance between the developing container and the screw cannot be regulated, and excessive discharge of the developer may not be suppressed. Further, screw lock and developer overflow due to the developer amount exceeding a predetermined amount cannot be suppressed.

  In patent document 3, there exists a subject of the cost increase by the additional member for generating a traveling wave electric field, and the enlargement of an apparatus.

  Therefore, the present invention does not increase the size of the apparatus, and at low cost, suppresses fluctuations in the amount of developer discharged in the developer container by tilting the developer container, and causes image defects such as longitudinal density unevenness and screw pitch unevenness. And the purpose of suppressing the occurrence of screw lock.

  In order to solve the above-described problems, a typical configuration of an image forming apparatus according to the present invention includes an image carrier that carries an electrostatic latent image, and a developer that includes a toner and a carrier. Developing means for developing the electrostatic latent image formed, and the developing means has a developing container for containing the developer and an agitating and conveying member for agitating and conveying the developer in the developing container. In the image forming apparatus having a developer discharge port for discharging the developer in the developer container to the outside of the developer container, the developer container includes an inclination detection unit that detects an inclination of the developer container, and the developer unit. Toner consumption calculating means for calculating consumption of toner used for development, and replenishing when the inclination detecting means determines that the developer discharge port is inclined downward Replenish the developer from the container The knowledge unit, when said developer discharge opening is determined to be inclined in a direction in which the upper is characterized by increasing the rotational speed of the stirring carrying member.

  According to the present invention, without increasing the size of the apparatus, the developer container is inclined at a low cost, thereby suppressing fluctuations in the discharge amount of the developer in the developer container, and images such as longitudinal density unevenness and screw pitch unevenness. The occurrence of defects, screw locks, and overflow of developer can be suppressed.

1 is a configuration diagram of an image forming apparatus according to an exemplary embodiment. (A) It is sectional drawing in the longitudinal direction of the developing device which concerns on this embodiment. (B) It is sectional drawing in the transversal direction of the image development apparatus concerning this embodiment. (A) It is sectional drawing of the image development apparatus in the state inclined in the direction in which a stirring chamber becomes relatively lower than a developing chamber. (B) It is sectional drawing of the image development apparatus in the state inclined in the direction in which the opening part by the side of a developer discharge port becomes relatively lower than another opening part. (A) Changes in the inclination angle detected by the inclination detection means when the developing device is inclined as shown in FIG. 3B and the amount of developer in the developing device when the developing device is driven without supply. FIG. (B) It is a figure which shows transition of the developer amount discharged | emitted from the inside of the developing device in each image ratio with respect to the inclination angle of the direction in which a developer reduces. (A) It is a figure which shows the relationship between the inclination angle of the direction in which a developer reduces, and required toner consumption. (B) It is a block diagram of the control part of the image forming apparatus which concerns on this embodiment. 7 is a flowchart of toner discharge control in the present embodiment. (A) It is sectional drawing of the image development apparatus in the state inclined in the direction in which a stirring chamber becomes relatively higher than a developing chamber. FIG. 5B is a cross-sectional view of the developing device in a state where the opening on the developer discharge port side is inclined in a direction in which the other opening is relatively higher. (A) It is a figure which shows transition of the discharge amount of the developer discharged | emitted from the inside of a developing device in each image ratio with respect to the inclination angle when a developing device inclines like FIG.7 (b). (B) is a diagram showing the relationship between the inclination angle in the direction in which the developer increases in this embodiment and the necessary rotational speed of the conveying screw. It is a figure which shows the relationship between the inclination angle of the direction where a developer increases when productivity falls when passing thick paper etc. in this embodiment, and the required rotational speed of a conveyance screw.

  An embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an image forming apparatus according to the present embodiment. As shown in FIG. 1, the image forming apparatus 100 of the present embodiment includes image forming units PY, PM, PC, and PBK that form yellow, magenta, cyan, and black images.

  In the image forming units PY to PBK, the photosensitive drums (image carriers) 1Y to 1BK are charged by the chargers 2Y to 2Bk, irradiated with laser light corresponding to the image information by the exposure device 3, and an electrostatic latent image is formed. It is formed. The electrostatic latent images formed on the photoconductive drums 1Y to 1BK are developed as toner images using toners of respective colors by developing devices (developing means) 4Y to 4BK.

  The developed toner image is primary-transferred over the intermediate transfer belt 51 by the primary transfer members 52Y to 52Bk. Transfer residual toner remaining on the photosensitive drums 1Y to 1BK after the primary transfer is removed by the cleaning devices 7Y to 7BK. The cleaned photosensitive drums 1Y to 1BK are neutralized by the neutralization devices 8Y to 8BK to prepare for the next image formation.

  On the other hand, the sheet S accommodated in the cassette 9 is conveyed to a nip portion (secondary transfer portion) between the secondary transfer roller 53 and the intermediate transfer belt 51 by a pickup roller, a conveyance roller, and a registration roller. Next is transferred. The sheet S on which the toner image is secondarily transferred is heated and pressed by the fixing device 6 to fix the toner image, and is discharged to the discharge tray 10. Deposits such as toner remaining on the intermediate transfer belt 51 after the secondary transfer are removed by the intermediate transfer belt cleaner 54.

(Developing device 4)
FIG. 2A is a cross-sectional view in the longitudinal direction of the developing device 4 according to this embodiment. FIG. 2B is a cross-sectional view of the developing device 4 according to the present embodiment in the short direction.

  As shown in FIGS. 2A and 2B, the developing device 4 includes a developing container 41, and a developing sleeve (developer carrying means) 44 and a regulating blade 46 are provided in the developing container. Yes. There is an opening at a position corresponding to the developing region of the developing container 41 facing the photosensitive drum 1, and the developing sleeve 44 is rotatably disposed in this opening so as to be partially exposed in the direction of the photosensitive drum 1. ing.

  The interior of the developing container 41 is horizontally divided into a developing chamber 41a and an agitating chamber 41b by a partition wall 41c extending substantially perpendicular to the paper surface. The two-component developer including toner and carrier is accommodated in the developing chamber 41a and the stirring chamber 41b.

  At the bottom of the developing chamber 41a, a first conveying screw (first agitating / conveying member) 42 is disposed substantially in parallel along the axial direction of the developing sleeve 44. The first conveying screw 42 rotates in the counterclockwise direction (arrow direction) in FIG. 2B and conveys the developer in the developing chamber 41a in one direction along the axial direction.

  A second conveying screw (second agitating / conveying member) 43 is disposed substantially parallel to the first conveying screw 42 at the bottom of the agitating chamber 41b. The second conveying screw 43 rotates in the opposite direction to the first conveying screw 42 (clockwise in FIG. 2B), and causes the developer in the stirring chamber 41b to move in the opposite direction to the first conveying screw 42. Transport. As described above, the developer is circulated between the developing chamber 41a and the agitating chamber 41b through the openings (communication portions) 41d and 41e at both ends of the partition wall 41c by being conveyed by the rotation of the screws 42 and 43.

  Further, a replenishment developer in which toner and carrier are mixed is supplied from a hopper (replenishment container) 20Y to 20BK (see FIG. 1) to a replenishment port provided in the stirring chamber 41b. On the other hand, excess developer is discharged out of the developing container from a developer discharge port 48a provided in the stirring chamber 41b. The discharged excess developer is transported to a collection box (not shown) by the developer transport member 48b in the surplus developer storage chamber 48.

  In this embodiment, the diameter of the developing sleeve 44 is 20 mm, the diameter of the photosensitive drum 1 is 80 mm, and the closest region between the developing sleeve 44 and the photosensitive drum 1 is a distance of about 300 μm. As a result, the developer conveyed to the development area is set to be able to be developed in a state where it is in contact with the photosensitive drum 1.

  The developing sleeve 44 is made of a nonmagnetic material such as aluminum or stainless steel, and a magnet roller 45 serving as a magnetic field means is installed in a non-rotating state therein. The magnet roller 45 has magnetic poles S1, S2, N1, N2, and N3.

  The developing sleeve 44 rotates in the clockwise direction in FIG. 2B during development, and carries a two-component developer whose layer thickness is regulated by cutting off the magnetic brush by the regulating blade 46. Then, the developer is conveyed to a developing area facing the photosensitive drum 1, and the developer is supplied to the electrostatic latent image formed on the photosensitive drum 1 to develop the latent image.

(Inclination angle detection sensor 600)
As shown in FIG. 2B, the developing device 4 has an inclination angle detection sensor (inclination detection means) 600. The sensor 600 detects the inclination angle of the developing device 4 (developing container 41). The sensor 600 detects various tilt angles with respect to the horizontal in a specific axial direction, detects various tilt angles with respect to the horizontal in all 360 ° directions, and outputs an electrical signal related to the detected tilt angle. A sensor can be used. In this embodiment, an inclination detection sensor of LCF2000 manufactured by JEWELL is used as the sensor 600.

  As shown in FIG. 5B, the sensor 600 is connected to the CPU 81 of the developing device 4. The sensor 600 is always in operation while the image forming apparatus 100 is powered on. Thereby, the inclination angle of the developing device 4 is always detected.

(Toner consumption calculation means)
As shown in FIG. 5B, the image forming apparatus 100 includes a reader unit 201 and a toner consumption calculation unit (image signal processing circuit 202, video counter 203). The toner consumption amount calculating means calculates the consumption amount of toner used for development by the developing device 4 by the following operation.

  The copy original D is projected by the reader unit 201. The reader unit 201 decomposes the document image into a large number of pixel units, and outputs a photoelectric conversion signal corresponding to the density of each pixel. An output from the reader unit 201 is transmitted to the image signal processing circuit 202.

  The image signal processing circuit 202 forms a pixel image signal having an output level corresponding to the density of the pixel for each pixel. At this time, the level of the output signal of the image signal processing circuit 202 is counted for each pixel and integrated by the video counter 203. The video count value V obtained by integrating the output signal level for each pixel corresponds to the amount of toner consumed by the developing device 4 to form one image of the document D. The video count value V is a ratio (%) of toner consumption in actual image formation to toner consumption (known) when an image having the maximum density level is formed on the entire surface of the image forming area, that is, an image ratio. Corresponds to (%).

  The video count value V is integrated every time one image is formed, and the video count integrated value V (n) is calculated. The integrated signal, that is, the video count integrated value V (n) is input to the CPU 81 as the control means and stored in the RAM 55 as the storage means. The video count integrated value V (n) is obtained for each of the image forming units PY to PK and stored in the RAM 55. Assume that the video count integrated values for the image forming units PY to PK are V1 (n), V2 (n), V3 (n), and V4 (n), respectively. The video count integrated values V1 (n) to V4 (n) correspond to values (image ratio integrated value:%) obtained by integrating the image ratio every time one image is formed.

(When the developer container is tilted in the direction of decreasing developer)
Here, the flow of the developer when the developer container 41 is inclined in the direction in which the developer in the developer container 41 decreases (the developer discharge port 48a is directed downward) will be described. FIG. 3A is a cross-sectional view of the developing device 4 in a state in which the stirring chamber 41b is tilted in a relatively lower direction than the developing chamber 41a. FIG. 3B is a cross-sectional view of the developing device 4 in a state where the opening 41d is inclined in a direction relatively lower than the opening 41e.

  As shown in FIG. 3A, when the developing container 41 is inclined in a direction in which the stirring chamber 41b is relatively lower than the developing chamber 41a, the developer is biased toward the wall surface on which the developer discharge port 48a is disposed. . For this reason, more developer is discharged from the developer discharge port 48a than when the developing container 41 is not inclined.

  As shown in FIG. 3B, when the developer container 41 is inclined in a direction in which the opening 41d is relatively lower than the opening 41e, the side where the developer discharge port 48a is disposed, that is, the opening 41d. The developer is biased in the direction. For this reason, more developer is discharged from the developer discharge port 48a than when the developing container 41 is not inclined.

  Therefore, when the developing device 4 tilts as shown in FIGS. 3A and 3B, a large amount of developer is discharged from the developer discharge port 48a, and the developer in the developing device decreases. If the developer is excessively reduced, image defects such as longitudinal density unevenness and screw pitch unevenness occur.

  Therefore, in the present embodiment, the inclination of the developing device 4 is detected by the sensor 600, and the developer is replenished from the hoppers 20Y to 20BK according to the detection result. However, the toner concentration (toner content) of the developer to be replenished is higher than the toner concentration of the developer (discharged developer) in the developing container 41. For example, the ratio of the developer toner and the carrier in the developer container 41 is 10:90, and the ratio of the developer toner and the carrier to be replenished is 90:10. The present invention is not limited to such a ratio, and it is sufficient that the carrier content in the developer in the hoppers 20Y to 20BK is set to be smaller than the toner content.

  Therefore, when the developer is simply replenished by the amount discharged from the developer discharge port 48a, the toner concentration in the developing container 41 increases. As a result, image defects such as fogging, toner scattering deterioration, and longitudinal density unevenness occur. Therefore, it is necessary to consume a predetermined amount of toner (necessary toner consumption) in order to keep the toner concentration in the developing container 41 constant.

  4A shows an inclination angle detected by the sensor 600 when the developing device 4 is inclined as shown in FIG. 3B, and a developer in the developing device when the developing device 4 is driven without supply. It is a figure which shows transition of quantity. FIG. 4B is a graph showing the transition of the amount of developer discharged from the developing device at each image ratio with respect to the inclination angle in the direction in which the developer decreases. FIG. 5A is a diagram showing the relationship between the inclination angle in the direction in which the developer decreases and the required toner consumption.

  Information as shown in FIG. 5A is stored in the CPU 81 as table data. The CPU 81 controls the image forming apparatus 100 so that the toner is consumed so as to reach the necessary toner consumption according to the inclination angle detected by the sensor 600 and the developer is replenished according to the consumption. .

  As a result, the amount of developer in the developing device does not fall below the amount that causes image defects such as uneven longitudinal density and uneven screw pitch. In addition, it is possible to suppress the occurrence of image defects such as fogging, deterioration of toner scattering, and longitudinal density unevenness due to high toner concentration.

  When the image ratio of the output product (calculation result of the toner consumption calculation means) is larger than the value calculated according to the detected inclination angle, it is not necessary to consume more toner. On the other hand, when the image ratio of the output product is smaller than the value calculated in accordance with the tilt angle, each of the image forming units PY to PK receives light from the developing device 4 at a predetermined timing other than during the image forming operation. A toner discharging operation for positively discharging toner to the body drum 1 is performed.

  In the present embodiment, the toner discharged from the developing device 4 is primarily transferred onto the intermediate transfer belt 51. On the other hand, a voltage (negative polarity) opposite to the secondary transfer bias is applied to the secondary transfer roller 53, so that the toner on the intermediate transfer belt 51 is not secondarily transferred to the secondary transfer roller 53 side. Then, it passes through the secondary transfer portion N2. Thereafter, the discharged toner on the intermediate transfer belt 51 is collected by the intermediate transfer belt cleaner 54.

  Further, the amount of discharged toner is increased by increasing the density of the toner image formed on the image carrier in the toner discharging operation, or by increasing the formation time of the toner image (increasing the area of the toner image). Can do.

  The predetermined timing other than the time of image formation is set at the time of pre-rotation, post-rotation, or between papers, or when the amount of toner consumption is not sufficient, a toner discharge operation is performed with a downtime. The pre-rotation is a preparatory operation period for driving the image forming element including the photosensitive drum 1 before the image forming operation for forming an image to be transferred to the intermediate transfer belt 51 and output. The post-rotation is a period of a preparatory operation for driving the image forming element including the photosensitive drum 1 after an image forming operation for forming an image to be transferred to the intermediate transfer belt 51 and output. The interval between sheets is a period corresponding to the interval between successive intermediate transfer belts 51 during a continuous image forming operation for a plurality of intermediate transfer belts 51.

  FIG. 6 is a flowchart of toner discharge control in this embodiment. As shown in FIG. 6, when the operation of the image forming apparatus 100 is started, the number of image formed sheets from the previous toner discharge timing is counted (S1). In the present embodiment, the number of image formations is counted by the CPU 81 that functions as a counter. When the count value reaches the predetermined number n (S2), the CPU 81 sets the image forming units PY to PK based on the video count integrated values V1 (n) to V4 (n) as follows. It is determined whether or not the toner discharging operation is to be executed.

  The CPU 81 calculates an average image ratio (per image) based on the video count integrated values V1 (n) to V4 (n) stored for each of the image forming units PY to PK and the image forming number n. %) (Calculation result of toner consumption calculation means). Here, as described above, the video count integrated values V1 (n) to V4 (n) correspond to the image ratio integrated value (%) in forming a predetermined number n of images. Here, for convenience, the average image ratio (%) for each of the image forming units PY to PK is set to V1 (n) / n, V2 (n) / n, V3 (n) / n, and V4 (n), respectively. Expressed as / n.

  Next, for each of the image forming units PY to PK, the CPU 81 calculates a predetermined amount of necessary toner calculated from the average image ratios V1 (n) / n to V4 (n) / n and the detection result of the sensor 600. The discharge amount values α1, α2, α3, and α4 (%) are compared. Then, when each of the average image ratios V1 (n) / n to V4 (n) / n is smaller than the necessary toner discharge amount values α1 to α4 (%), it is determined to execute the toner discharge operation (S3). To S6).

  When determining that the toner discharging operation is to be executed, the CPU 81 causes the developing device 4 so that the average image ratio of each of the image forming units PY to PK is equal to the corresponding required toner discharge amount values α1 to α4. The amount of toner discharged from the toner to the photosensitive drum 1 is calculated (S7). Then, the CPU 81 causes the toner discharge operation to be executed according to the calculated discharge toner amount (S8).

  In this embodiment, in the toner discharging operation, first, the photosensitive drum 1 is charged by the charging roller 2 as in the normal image forming operation. Thereafter, an electrostatic image is formed on the photosensitive drum 1 by the exposure device 3 so that the average image ratio of each of the image forming units PY to PK is equal to the necessary toner discharge amount values α1 to α4. Then, by developing the electrostatic image with the developing device 4, toner is discharged from the developing device 4 onto the photosensitive drum 1.

  Here, in the present embodiment, the predetermined number n for calculating the average image ratio is 200. In the present embodiment, the necessary toner discharge amount values α1 to α4 are the same as the threshold values of the average image ratio for determining whether or not to execute the toner discharge operation in the image forming units PY to PK, respectively.

  By discharging the toner, the toner density in the developing device 4 decreases, but the toner corresponding to the discharged amount is supplied from the toner hopper 20 (S9). When the toner discharge operation as described above is completed, the counter is reset (S10), and a normal image forming operation is performed (S11).

  Note that the above-described toner discharging operation in this embodiment is performed between sheets. However, the toner discharging operation may be performed as long as it is performed at the time of non-image formation, and may be performed at the time of pre-rotation or post-rotation of the image forming operation, or by providing a down time. Further, such toner discharge operation need not be performed simultaneously in all the image forming units PY to PK, and may be performed at different timings in the respective image forming units PY to PK.

  As described above, when the developing device 4 is tilted in the direction in which the developer decreases, it is possible to suppress image defects such as longitudinal density unevenness and screw pitch unevenness.

  Regarding the configuration of the developing device, in this embodiment, the developing chamber 41a and the agitating chamber 41b are arranged horizontally, but the developing device in which the developing chamber 41a and the agitating chamber 41b are arranged up and down, or other forms The present invention can also be applied to a developing device.

(When the developer container is tilted in the direction of increasing developer)
Here, the flow of the developer when the developer container 41 is tilted in the direction in which the developer in the developer container 41 decreases (the direction in which the developer discharge port 48a faces up) will be described. FIG. 7A is a cross-sectional view of the developing device 4 in a state in which the stirring chamber 41b is inclined in a relatively higher direction than the developing chamber 41a. FIG. 7B is a cross-sectional view of the developing device 4 in a state where the opening 41d is inclined in a direction relatively higher than the opening 41e.

  As shown in FIG. 7A, when the developing container 41 is inclined in a direction in which the stirring chamber 41b is relatively higher than the developing chamber 41a, the developer discharge port 48a is disposed in the developer in the stirring chamber 41b. It is biased toward the partition wall 41c opposite to the wall surface. For this reason, the developer discharged from the developer discharge port 48a is reduced as compared with the case where the developing container 41 is not inclined.

  As shown in FIG. 7B, when the developing container 41 is inclined in a direction in which the opening 41d is relatively higher than the opening 41e, the side opposite to the side where the developer discharge port 48a is disposed, that is, the opening. The developer is biased toward the portion 41e. For this reason, the developer discharged from the developer discharge port 48a is reduced as compared with the case where the developing container 41 is not inclined.

  Therefore, when the developing device 4 is tilted as shown in FIGS. 7A and 7B, the developer discharged from the developer discharge port 48a decreases, and the developer in the developing device increases. If the developer increases too much, screw lock, overflow of the agent, etc. will occur.

  Therefore, in this embodiment, the inclination of the developing device 4 is detected, and the rotational speeds of the screws 42 and 43 are changed in order to reduce the developer according to the detection result. That is, when the developer is inclined in the increasing direction, the rotational speed of the screws 42 and 43 is increased to increase the amount (discharge amount) of the developer passing through the developer discharge port 48a. The developer in 41 is reduced.

  FIG. 8A is a diagram showing the transition of the discharge amount of the developer discharged from the developing device at each image ratio with respect to the inclination angle when the developing device 4 is inclined as shown in FIG. 7B. FIG. 8B is a diagram showing the relationship between the inclination angle in the direction in which the developer increases and the necessary rotational speed of the screws 42 and 43 in this embodiment.

  Information as shown in FIG. 8B is stored in the CPU 81 as table data. The CPU 81 changes the rotational speed of the screws 42 and 43 to a necessary rotational speed in order to prevent the amount of developer in the developing device from exceeding a certain level in accordance with the inclination angle detected by the sensor 600. The image forming apparatus 100 is controlled. Thereby, the occurrence of screw lock and developer overflow is suppressed.

  In the present embodiment, the rotational speed of the screws 42 and 43 when the inclination angle is 0 ° is 250 mm / sec. When the developer is inclined in the increasing direction, the rotation speed of the screws 42 and 43 is increased in accordance with the inclination angle, and the amount (discharge amount) of the developer in the developing device 4 passing through the developer discharge port 48a. ) Is adjusted.

  FIG. 9 is a diagram showing the relationship between the inclination angle in the direction in which the developer increases when the productivity decreases when passing thick paper or the like in the present embodiment, and the necessary rotation speed of the screws 42 and 43. In the image forming apparatus 100 according to the present embodiment, when a sheet S having a large basis weight or a sheet S called glossy coated paper is passed, productivity is reduced in order to ensure fixability. . Decreasing productivity means decreasing the speed of the entire image forming apparatus, and the developing apparatus 4 also decreases the speed as a whole. That is, the speed of the developing sleeve 44 and the screws 42 and 43 in the developing device 4 is also reduced.

  Information indicating the relationship between the necessary rotation speed of the screws 42 and 43 and the inclination angle shown in FIG. 9 assuming such a case is stored in the CPU 81 as table data. Thereby, even when passing thick paper or the like, the occurrence of screw lock and developer overflow can be suppressed.

D ... Original to be copied P ... Image forming section S ... Sheet 1 ... Photosensitive drum (image carrier)
3 ... exposure device 4 ... developing device (developing means)
20 ... Hopper (supplement container)
41... Developing container 41 a... Developing chamber 41 b... Stirring chambers 41 d and 41 e... Opening 42.
43 ... 2nd conveyance screw (stirring conveyance member)
44 ... Development sleeve 45 ... Magnet roller 46 ... Restriction blade 48 ... Excess developer storage chamber 48a ... Developer discharge port 48b ... Developer transport member 51 ... Intermediate transfer belt 55 ... RAM
81 ... CPU
DESCRIPTION OF SYMBOLS 100 ... Image forming apparatus 201 ... Reader part 202 ... Image signal processing circuit (toner consumption calculation means)
203 ... Video counter (toner consumption calculation means)
600 ... Inclination angle detection sensor (inclination detection means)

Claims (3)

An image carrier for carrying an electrostatic latent image;
Developing means for developing the electrostatic latent image carried on the image carrier using a developer comprising toner and a carrier,
The developing means has a developing container for storing a developer, and an agitating and conveying member for stirring and conveying the developer in the developing container,
In the image forming apparatus, the developer container has a developer discharge port for discharging the developer in the developer container to the outside of the developer container.
An inclination detecting means for detecting the inclination of the developing container;
Toner consumption amount calculating means for calculating consumption amount of toner used for development by the developing means,
When it is determined by the tilt detection means that the developer discharge port is tilted in the downward direction, the developer is replenished from the replenishing container,
2. An image forming apparatus according to claim 1, wherein when the inclination detecting unit determines that the developer discharge port is inclined upward, the rotation speed of the agitating and conveying member is increased.
If it is determined by the inclination detection means that the developer discharge port is inclined downward, based on the detection result of the inclination detection means and the calculation result of the toner consumption calculation means, The toner according to claim 1, wherein a predetermined amount of toner is consumed during non-image formation, and the amount of developer in the developer container is adjusted by replenishing the developer in accordance with the toner consumed from the supply container. Image forming apparatus.
  The image forming apparatus according to claim 1, wherein the carrier content in the developer in the replenishing container is set to be lower than the toner content.

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