JP2006106514A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of more stabilizing the replenishment of developer to a developing device. <P>SOLUTION: The image forming apparatus comprising a developing device 4, a first container 51 for storing developer to be replenished to the developing device 4, a first replenishing means 53 for discharging the developer from the first container 51 and replenishing the developer to the developing device 4, a second container 57 for storing developer to be replenished to the first container 51, a second replenishing means 58 for discharging developer from the second container 57 and replenishing the developer to the first container 51, and a detection means 56 for detecting the developer stored in the first container 51 is constituted so as to have a normal replenishment mode for driving the second replenishing means 58 and replenishing the developer to the first container 51 when the detection means 56 detects that the developer in the first container 51 is less than prescribed quantity and a forced replenishment mode for driving the second replenishing means 58 independently of the detection result of the detection means 56 and replenishing the developer to the first container 51. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a copying machine, a laser printer, a facsimile machine, etc. using an electrophotographic system, an electrostatic recording system, etc., which forms an image by developing an electrostatic image formed on an image carrier using a developer. The present invention relates to an image forming apparatus.

  2. Description of the Related Art Conventionally, for example, in an electrophotographic image forming apparatus, an electrostatic image (latent image) formed on an electrophotographic photosensitive member (hereinafter referred to as “photosensitive drum”) that is generally cylindrical as an image carrier is used. A developing device is used for visualizing with a developer. As the developer, a two-component developer including a nonmagnetic toner and a magnetic carrier is widely used.

  As a developing method, the following magnetic brush developing method is known. That is, as a developer carrying member, a magnetic brush is formed on the surface of a developing sleeve having a magnet disposed therein, and this magnetic brush is rubbed or brought close to an opposing photosensitive drum while holding a minute developing gap. Then, by continuously applying an alternating electric field between the developing sleeve and the photosensitive drum (between S and D), the toner particles are repeatedly transferred and reversely transferred from the developing sleeve side to the photosensitive drum side. I do.

  For example, in the image forming apparatus using the two-component developer as described above, the toner is consumed as the image is formed. Therefore, it is necessary to replenish the developer appropriately.

  With reference to FIG. 2, the structure of the developing device for developing the two-component magnetic brush and the developer supplying device for supplying the developer to the developing device will be described. FIG. 2 shows a schematic cross section of the developing device and the developer supply device.

  The developing device 4 includes a developing sleeve 46 as a developer carrying member in a developing container (developing device main body) 41, a magnet roller 47 as a magnetic field generating unit fixedly arranged in the developing sleeve 46, A developing screw 44 and a stirring screw 45 for stirring and transporting the developer, a toner receiving hole 49, and a regulating blade 48 arranged for forming a thin layer of the developer on the surface of the developing sleeve 46 are provided. The inside of the developing container 41 is substantially divided into a developing chamber 42 and a stirring chamber 43. The developing screw 44 is disposed in the developing chamber 42, and the stirring screw 45 is disposed in the stirring chamber 43. As shown in the figure, the developing sleeve 46 is disposed close to the photosensitive drum 1 and rotates in the opposite direction or the same direction as the photosensitive drum 1, and the developer (shaded portion in the figure) comes into contact with the photosensitive drum 1. It is set so that development can be performed in a state.

  The developer supply device 50 includes a sub toner container 51 that stores toner to be supplied to the developing device 4. A toner supply port 60 through which toner can be supplied is formed above the sub toner container 51. Further, below the sub toner container 51, a toner transport pipe 52 capable of transporting toner from the sub toner container 51 is formed in a cylindrical shape so as to protrude in a substantially horizontal direction. A replenishing screw 53 having a spiral surface formed on the rotation shaft is rotatably provided in the toner transport pipe 52. The replenishing screw 53 is connected to a driving means 54 that rotationally drives the replenishing screw 53. The sub-toner container 51 is provided with a toner sensor (toner presence / absence detection sensor) 56 that directly or electrically detects the presence / absence of toner. Furthermore, a stirring member 55 is provided inside the sub toner container 51 so as to be rotatable or rotatable.

  The developer replenishing device 50 further includes a main toner container 57 that is provided above the sub toner container 51 and stores toner to be replenished to the sub toner container 51. In the main toner container 57, a stirring and conveying member 58 is rotatably provided. The agitating / conveying member 58 is connected to a driving means 59 for rotationally driving the agitating / conveying member 58. The main toner container 57 is configured to be detachable from the sub toner container 51 and the image forming apparatus main body, and is generally called a toner cartridge (or toner bottle).

  The developer container 41 contains a two-component developer in which non-magnetic toner particles (toner) and magnetic carrier particles (carrier) are mixed. The mixing ratio of toner and carrier (hereinafter referred to as “T / C ratio”) is kept constant by supplying an amount of toner commensurate with the toner consumed by development. That is, the toner is dropped from the sub-toner container 51 in which the replenishment toner is stored by the replenishment screw 53 through the receiving hole 49 of the developing container 41 to the agitation chamber 43 provided with the agitation screw 45 and then to the developing device 4. Will be replenished. Various methods have been put to practical use as methods for detecting and maintaining the T / C ratio of the developer in the developing container 41 at this time.

  In order to keep the T / C ratio of the developer in the developing container 41 constant, the replenishment screw 53 is driven to rotate for the time or the number of rotations corresponding to the amount of toner consumed by the development, and the toner in the sub-toner container 51 Transport. To stabilize the developer T / C ratio in the developing container 41, and thus stabilize the image density during image formation, the amount of toner conveyed when the replenishing screw 53 is rotated for a predetermined time or number of rotations. That is, it is necessary that the amount of toner replenished per unit time or unit rotation number is stable.

  For this purpose, it is important that the toner density in the sub-toner container 51 is maintained at a certain amount or more. In particular, when the capacity of the sub-toner container 51 is small in a small image forming apparatus or the like, the toner accumulation in the sub-toner container 51 tends to be uneven, and the amount of toner conveyed from the receiving hole 49 tends to vary.

  For example, the amount of toner used at the time of image formation can be calculated from the image density for image formation, and toner can be supplied by rotating a time supply screw according to the calculation result. In this case, it is difficult to stably control the T / C ratio in the developing container 41 unless the amount of toner conveyed per unit time is stable.

  By the way, when the user purchases the device, for example, when the device is installed (when the device shipped from the factory is in a usable state for the first time) or when the main toner container 57 is replaced, The toner is not filled or is in a low state. In view of this, there is known an apparatus that performs a “toner forcible replenishment operation” when the apparatus is installed or when an unused developer is filled in a developing device. In Patent Document 1 and Patent Document 2, a predetermined toner from a main toner container (toner bottle) to a sub toner container (toner replenisher, toner hopper) is detected according to a detection result of a toner end sensor installed in a toner replenisher (sub toner container). Control means for carrying out the supply operation and the developer stirring operation in the developing device is disclosed.

  The above prior art is configured to perform a predetermined toner supply operation in accordance with a detection value of a toner end sensor provided in the toner replenishing unit. That is, when the apparatus is installed, it is determined whether or not the inside of the sub toner container is empty using the detection result of the toner end sensor, and when it is determined that the sub toner container is empty, a predetermined replenishment operation is performed.

  However, according to the study by the present inventors, even when the toner end sensor in the sub toner container detects the presence of toner, the amount of toner in the sub toner container is not always stable. For example, when the main toner container is mounted, if the toner is dropped to the sub toner part by its own weight, the amount of toner falling to the sub toner part when the main toner container is mounted is not constant. This is because the toner state (tightening) in the main toner container varies greatly depending on the storage state of the main toner container and the transport state during transportation. Therefore, when the main toner container is mounted, even if the detection result of the toner end sensor indicates that there is toner, the toner density in the sub toner container may not be sufficient.

  In particular, in the case of a small image forming apparatus, the capacity of the sub-toner container is very small as described above. Furthermore, the fluidity of powders such as toner is likely to decrease due to environmental fluctuations. Therefore, when toner is accumulated in the sub-toner container, it is often accumulated non-uniformly.

  For example, depending on the position of the stirring member in the sub toner container, although there is toner around the toner sensor that detects the presence or absence of toner, there are cases where sufficient toner is not filled in the sub toner container. Alternatively, although there is toner around the toner sensor, there may be a space in the sub-toner container.

  In particular, when replacing the main toner container, normally, after the toner in the main toner container is used up, the toner in the sub toner container is used for a while and image formation is continued. The toner density tends to decrease.

In the above, the conventional problems have been described by taking a developing device for two-component magnetic brush development using a two-component developer as a developer and a magnetic brush developing method as a developing method as an example. In addition to the two-component magnetic brush development method, various methods such as a one-component contact development method have been put into practical use. Even when a developer different from the two-component developer is used and a developing method different from the magnetic brush developing method is used, the sub-toner container (first container) and the main toner container (second container) are separated. In the image forming apparatus including the developer supply device having the same problem as described above may occur.
JP-A-8-227216 JP-A-10-55099

  An object of the present invention is to provide an image forming apparatus capable of further stabilizing the replenishment of developer to a developing device.

  Another object of the present invention is an image forming apparatus including a first container for storing a developer to be replenished in a developing device, and a second container for storing the developer to be replenished in the first container. It is possible to stabilize the toner density in the first container at the time of installation of the apparatus or immediately after replacement of the second container, and to output a stable image with little density fluctuation, particularly in a small-sized image forming apparatus. An image forming apparatus is provided.

The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention relates to a developing device for developing an electrostatic image using a developer, a first container for storing the developer to be replenished to the developing device, and a developer from the first container. A first supply means for discharging and supplying the developer; a second container for storing developer to be supplied to the first container; and discharging the developer from the second container to discharge the first container. An image forming apparatus comprising: a second supply unit that supplies the container; and a detection unit that detects the developer in the first container.
A normal replenishment mode in which the second replenishing unit is driven to replenish the developer in the first container when the detecting unit detects that the developer in the first container is less than a predetermined amount. When,
A forced replenishment mode for replenishing developer to the first container by driving the second replenishment means regardless of the detection result of the detection means;
An image forming apparatus comprising:

  According to the present invention, it is possible to further stabilize the supply of developer to the developing device. According to the invention, there is provided an image forming apparatus including a first container for storing a developer to be replenished to the developing device and a second container for storing the developer to be replenished to the first container. It is possible to stabilize the toner density in the first container at the time of installation of the apparatus or immediately after replacement of the second container, and to output a stable image with little density fluctuation, particularly in a small image forming apparatus. is there.

  The image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.

Example 1
[Overall Configuration and Operation of Image Forming Apparatus]
First, the overall configuration and operation of the image forming apparatus of this embodiment will be described. FIG. 1 shows a schematic overall configuration of the image forming apparatus of this embodiment. The image forming apparatus 100 according to the present exemplary embodiment includes a document reading apparatus connected to an image forming apparatus main body (apparatus main body) or a yellow (Y ), Magenta (M), cyan (C), and black (K) full-color images can be formed on a recording material (recording paper, plastic sheet, cloth, etc.) using an electrophotographic system.

  The image forming apparatus 100 according to the present exemplary embodiment is a quadruple tandem image forming apparatus, and includes first, second, third, and fourth image forming stations PY, PM, PC, and PK as a plurality of image forming units. Have Further, the image forming apparatus 100 of the present embodiment employs an intermediate transfer method. That is, the intermediate transfer belt 7 that can be moved (rotated) as an intermediate transfer member moves in the direction of the arrow in the drawing, and the images of the respective colors are superimposed on the intermediate transfer belt 7 while passing through each image forming station. Then, the toner image on which the respective colors are superimposed on the intermediate transfer belt 7 is transferred to the recording material S to obtain a recorded image.

  In the present embodiment, the configuration of each image forming station is substantially the same except that the development colors are different. Therefore, in the following, unless there is a particular distinction, it is an element belonging to any image forming station. The subscripts Y, M, C, and K given to the reference numerals in order to indicate are omitted and will be described in general.

  The image forming station P has a photosensitive drum 1 as an image carrier. On the outer periphery of the photosensitive drum 1, there are a charging roller 2 as a charging means, an exposure device (laser exposure optical system in this embodiment) 3 as an exposure means, a developing device 4 as a developing means, and a cleaning device 6 as a cleaning means. Is provided. A primary transfer roller 5 as a primary transfer unit is disposed so as to face the photosensitive drum 1 with the intermediate transfer belt 7 interposed therebetween.

  At the time of image formation, the charging roller 2 uniformly charges the rotating photosensitive drum 1. Next, the exposure device 3 scans and exposes the charged surface of the photosensitive drum 1 according to an image information signal. As a result, an electrostatic image is formed on the photosensitive drum 1. The electrostatic image formed on the photosensitive drum 1 is developed as a toner image with a developer by the developing device 4. Thereafter, the toner image formed on the photosensitive drum 1 is transferred onto the intermediate transfer belt 7 at a primary transfer portion (nip) N1 where the intermediate transfer belt 7 and the photosensitive drum 1 abut.

  For example, when a four-color full-color image is formed, an image forming operation is performed at each image forming station with a delay by the time during which the intermediate transfer belt 7 moves the distance between the photosensitive drums 1 sequentially from the first image forming station PY. Done. Thus, as the intermediate transfer belt 7 moves, the toner images of the respective colors are sequentially transferred to the intermediate transfer belt 7 at the primary transfer portion N1 of each image forming station P, and the four color toner images are formed on the intermediate transfer belt 7. Is formed to form a multiple toner image.

  On the other hand, for example, the recording material S accommodated in the cassette 9 as the recording material accommodation portion is transferred to the intermediate transfer belt 7 and the secondary transfer means by a recording material conveying member such as a pickup roller, a conveying roller, and a registration roller. The toner image is conveyed in synchronization with the toner image on the intermediate transfer belt 7 to a secondary transfer portion (nip portion) N2 in contact with the next transfer roller 8.

  Thus, the multiple toner images on the intermediate transfer belt 7 are transferred onto the recording material S at the secondary transfer portion N2. Thereafter, the recording material S is separated from the intermediate transfer belt 7 and conveyed to the fixing device 10. The recording material S is heated and pressurized by the fixing device 10, and an unfixed toner image on the recording material S is fixed. Thereafter, the recording material S is discharged out of the apparatus.

  Deposits such as toner remaining on the photosensitive drum 1 after the primary transfer step are removed by the cleaning device 6. Further, deposits such as toner remaining on the intermediate transfer belt 7 after the secondary transfer step are removed by the intermediate transfer body cleaner 11.

  Note that it is also possible to form a single color or multi-color image by using an image forming unit for a desired single color or some of four colors such as a black single color image.

  In this embodiment, the image forming apparatus 100 is described as adopting the intermediate transfer method, but the present invention is not limited to this. As known to those skilled in the art, instead of the intermediate transfer member 7, there is an image forming apparatus provided with a recording material carrier that carries a recording material and conveys it to the nip portion with each photosensitive drum 1. In this case, in each image forming station, the toner images of the respective colors are multiplex-transferred onto the recording material on the recording material carrier, and then the recorded images are obtained by fixing the multiplex toner images. The present invention is equally applicable to such an image forming apparatus.

[Configuration and operation of the developer]
Next, the developing device 4 will be further described with reference to FIG. As shown in FIG. 2, the developing device 4 disposed opposite to the photosensitive drum 1 includes a developing sleeve 46 as a developer carrying member in a developing container 41 and a magnetic field generating unit disposed in the developing sleeve 46. A fixed magnet roller 47, a regulating blade 48 as a developer amount regulating means arranged to form a thin layer of developer on the surface of the developing sleeve 46, and the developer in the developing container 41 are stirred. And a developing screw 44 and a stirring screw 45 to be conveyed.

  The inside of the developing container 41 is divided into a developing chamber (first chamber) 42 and an agitating chamber (second chamber) 43 by a partition wall 41a extending in a substantially vertical direction. The developing screw 44 is disposed in the developing chamber 42, and the stirring screw 45 is disposed in the stirring chamber 43.

  In the developing container 41, a two-component developer including nonmagnetic toner particles (toner) and magnetic carrier particles (carrier) is accommodated. The agitating screw 45 agitates and conveys the toner replenished from the developer replenishing device 50, which will be described in detail later, through the receiving hole 49, and the developer already in the agitating chamber 43, thereby uniformizing the toner concentration. To do. The developing screw 44 supplies the developer onto the developing sleeve 46 while stirring and conveying the developer. The development screw 44 and the agitation screw 45 convey the developer in opposite directions along the rotation axis direction (longitudinal direction) of the development sleeve 46. In addition, on the front side and the back side of the partition wall 41a, a communication portion through which the developer can pass is formed between the developing chamber 42 and the stirring chamber 43. Thus, the developer circulates in the developing container 41 by the conveying force of the developing screw 44 and the stirring screw 45.

  A part of the developing chamber 42 of the developing device 4 facing the photosensitive drum 1 is opened, and a developing sleeve 46 is rotatably arranged so as to be partially exposed to the opening. In this embodiment, the developing sleeve 46 is made of a non-magnetic material, is disposed close to the photosensitive drum 1, and rotates in the direction indicated by the arrow in the developing operation. The developing sleeve 46 carries the two-component developer whose layer thickness is regulated by the developing blade 48 and conveys it to the developing region facing the photosensitive drum 1. The developer on the developing sleeve 46 rises (magnetic brush) in the developing region and contacts the photosensitive drum 1 by the magnetic field generated by the magnet roller 47. In order to improve development efficiency, a predetermined development bias in which a DC voltage is superimposed on an AC voltage is usually applied to the development sleeve 46 during the development process. Thereby, the toner is transferred from the magnetic brush to the photosensitive drum 1 in accordance with the electrostatic image formed on the photosensitive drum 1.

[Developer supply device]
Next, the developer supply device 50 will be described. The configuration of the developer supply device 50 of the present embodiment is the same as that of the conventional one, but is characterized by drive control of the developer supply device.

  The developer supply device 50 has a sub-toner container 51 as a first container for storing toner to be supplied to the developing device 4. A toner supply port 60 through which toner can be supplied is formed above the sub toner container 51. Further, below the sub toner container 51, a toner transport pipe 52 capable of transporting toner from the sub toner container 51 is formed in a cylindrical shape so as to protrude in a substantially horizontal direction. A supply screw 53 having a spiral surface formed on the rotation shaft is rotatably provided in the toner transport pipe 52 as a first supply means. The replenishing screw 53 is connected to a driving means 54 that rotationally drives the replenishing screw 53. The sub-toner container 51 also detects whether the toner in the sub-toner container 51 has a predetermined amount or more (with toner) or less than the predetermined amount (no toner) as detection means for detecting the toner in the sub-toner container 51. A toner sensor (toner presence / absence detection sensor) 56 for detection is provided. In this embodiment, a piezoelectric element (piezo sensor) is used as the toner sensor 56, and when the toner amount in the sub-toner container 51 is a predetermined amount or more (predetermined density or more), a detection signal indicating the presence of toner is controlled by the control means 90 (FIG. 3). When the amount of toner in the sub-toner container 51 is equal to or less than a predetermined amount (less than a predetermined density), a detection signal indicating no toner is input to the control means 90. Furthermore, a stirring member 55 is provided inside the sub toner container 51 so as to be rotatable or rotatable.

  The developer replenishing device 50 further includes a main toner container 57 as a second container that is provided above the sub toner container 51 and stores toner to be replenished to the sub toner container 51. In the main toner container 57, a stirring and conveying member 58 as a second replenishing means is rotatably provided. The agitating / conveying member 58 is connected to a driving means 59 for rotationally driving the agitating / conveying member 58.

  In FIG. 2A, for easy understanding, the longitudinal direction of the photosensitive drum 1 and the developing container 41 is set to a direction perpendicular to the paper surface, the sub-toner container 51 (replenishment screw 53, toner transport pipe 52) and the main body. Although the longitudinal direction of the toner container 57 is drawn in a direction parallel to the paper surface, in practice, these longitudinal directions are generally the same direction. FIG. 2B is a plan view of the sub toner container 51 and the main toner container 57 viewed in the longitudinal direction.

  First, an operation of replenishing toner from the main toner container 57 to the sub toner container 51 when the toner in the sub toner container 51 decreases as the toner is consumed will be described.

  The agitating member 55 of the sub-toner container 51 acts to rotate or rotate to loosen the toner and prevent the toner from solidifying in the sub-toner container 51. The replenishing screw 53 conveys the toner in the sub-toner container 51 in a longitudinal direction (a direction parallel to the middle sheet surface of FIG. 2A) toward the receiving hole 49 communicating with the developing container 41, and the toner. It pushes out from the receiving hole 49 and drops into the developing container 41.

  After the toner sensor 56 detects the absence of toner, if the toner-free state continues even if the stirring member 55 operates for a predetermined time (predetermined amount), the toner is solidified in a part of the sub-toner container 51. Instead, it can be determined that the toner has run out. In this case, the control means 90 (FIG. 3) executes toner supply from the main toner container 57 to the sub toner container 51 (normal supply mode).

  In order to convey the toner from the main toner container 57 to the sub toner container 51, the stirring and conveying member 58 in the main toner container 57 is driven to rotate. The agitating / conveying member 58 prevents the toner from solidifying in the main toner container 47 by rotating, and also causes the toner in the main toner container 57 to move in the longitudinal direction toward the toner supply port 60 communicating with the sub toner container 51 ( 2A, the toner is pushed out from the toner supply port 60 and dropped into the sub-toner container 51.

  As the agitating / conveying member 58, a blade-like sheet material rotating around the rotation axis can be suitably used. The sheet material is rotated while being appropriately bent so as to rub against the inner wall of the main toner container 57, thereby conveying the toner in the main toner container 57 toward the toner supply port 60 while stirring. As the sheet material of the stirring and conveying member 58, for example, a sheet material such as PET can be suitably used. If the stirring / conveying member 58 made of such a sheet material is used, the toner is not pushed into the sub toner container 51 more than necessary.

  If the toner sensor 56 does not detect the presence of toner even if the stirring / conveying member 58 of the main toner container 57 is rotated for a sufficient time, the toner is not replenished to the sub toner container 51, that is, the toner in the main toner container 58 is also lost. Can be judged. In this case, the control means 90 (FIG. 3) is a display means such as an operation unit (operation panel) (not shown) provided in the image forming apparatus 100 or a screen of a host device connected to be communicable with the image forming apparatus 100. Through this, the user is informed that there is no toner in the main toner container 57. After the agitating and conveying member 58 of the main toner container 57 has been rotated for a sufficient time, when the toner sensor 56 does not detect the presence of toner, it is determined that there is no toner in the main toner container 57. False detection can be prevented.

  In this embodiment, the main toner container 57 is configured to be detachable from the sub toner container 51 and the image forming apparatus main body as a so-called toner cartridge (or toner bottle). When the toner in the main toner container 57 runs out, the main toner container 57 is replaced. Alternatively, a new main toner container 57 is attached when the image forming apparatus is purchased. At this time, the handle (not shown) provided on the main toner container 57 is tilted to attach the main toner container 57 to the image forming apparatus main body, and the toner supply port 60 is opened. When the main toner container 57 is attached, the toner falls from the main toner container 57 to the sub toner container 51 by its own weight.

  However, the present invention is not limited to an embodiment in which the main toner container (second container) 57 is detachable. For example, when the main toner container (second container) 57 is fixed to the main body of the image forming apparatus, the main toner container (second container) 57 is directly filled with toner from another container. It is possible to take.

  Next, a toner replenishing operation from the sub toner container 51 to the developing device 4 will be described.

  The replenishing screw 53 of the sub toner container 51 is rotated by the driving means 54. The number of rotations or the rotation time of the replenishment screw 53 is determined by the control unit 90 in a timely manner according to the amount of toner required for the developing device 4. Then, under the control of the control means 90 (FIG. 3), the replenishment screw 53 rotates by the determined number of rotations or rotation time, and stops rotating when the determined number of rotations or rotation time is reached. As a result, the developer replenishing device 50 conveys as much toner as required by the developing device 4 and replenishes the developing container 41.

  Here, the toner amount required for the developing device 4 can be obtained by any available means. For example, as a method for obtaining a toner replenishment amount corresponding to the amount of toner consumed by development, as a result of detecting the T / C ratio (toner concentration) of the developer provided in the developing device 4 by the toner concentration detection means, the image information signal The image carrier (photosensitive member, intermediate transfer member, recording material carrier) is the integrated value (video count) of density information for each pixel or the density of a reference image (patch image) formed by developing a predetermined electrostatic image. Etc.) and a method of obtaining from the result detected by the image density detecting means or a combination thereof.

  At this time, according to the configuration (size, etc.) of the replenishing screw 53, the toner conveyance amount per rotation or per unit time is made constant in advance. Therefore, it is possible to control to calculate the number of rotations or the rotation time according to the required amount.

  Next, the drive configuration of the developer supply device 50 will be described.

  FIG. 3 shows a layout of the driving configuration of the developing device 4 and the developer supply device 50. As described above, the developing device 4 can develop the electrostatic image on the photosensitive drum 1 into a visible image using the developer stored inside. That is, the developing device 4 includes a developing screw 44 and a stirring screw 45 that are stirring and transporting means for stirring and transporting the developer in the developing device 4. Further, as described above, the developer replenishing device 50 is a sub toner container 51 that stores toner to be replenished to the developing device 4, and a first replenishing unit that discharges toner from the sub toner container 51 and replenishes the developing device 4. A replenishment screw 53, a main toner container 57 for storing toner to be replenished to the sub toner container 51, and a stirring and conveying member 58 as second replenishing means for discharging the toner from the main toner container 57 and replenishing it to the sub toner container 51 are provided.

  The drive mechanism of the developer replenishing device 50 is a motor 80 that is a rotational drive means capable of transmitting the drive to the replenishment screw 53 and the stirring and conveying member 58, and a drive that can transmit the rotation of the motor 80 to the replenishing screw 53 and the stirring and conveying member 58. It has a gear train 70. That is, the drive gear train 70 can be switched between at least two states, a first state in which the rotation of the motor 80 can be transmitted to the replenishment screw 53 and a second state in which the rotation can be transmitted to the stirring and conveying member 58. Have means.

  More specifically, the drive gear train 70 has a first drive gear 73a on the motor 80 side and a second drive gear 73b that meshes with the first drive gear 73a, and the second drive gear 73b is on the supply screw 53 side. It selectively meshes with the first intermediate gear 71 that transmits the drive and the second intermediate gear 72 that transmits the drive to the stirring and conveying member 58 side. Further, the first intermediate gear 71 transmits drive to a supply screw drive gear 54 that is a drive means for the supply screw 53, and the second intermediate gear 72 transmits drive to an agitation transport member drive gear 59 that is a drive means for the agitation transport member. . The second gear 73b is rotatably supported by a lever 73c that is pivotally supported around the rotation center of the first gear 73a. The motor 80 can rotate in both forward and reverse directions, and the control unit 90 controls the rotation and stop of the motor 80 in both forward and reverse directions.

  When the motor 80 rotates in the direction A1 in the figure, the lever 73c rotates in the direction A2 in the figure, and the second drive gear 73b transmits the drive to the first intermediate gear 71. Conversely, when the motor rotates in the direction B1 in the figure, the lever 73c rotates in the direction B2 in the figure, and the second drive gear 73b transmits the drive to the second intermediate gear 72. As a result, when the motor 80 rotates in the direction A1 in the drawing, the replenishing screw 53 rotates with the stirring and conveying member 58 stopped. Further, when the motor 80 rotates in the direction B1 in the drawing, the agitating and conveying member 58 rotates while the replenishing screw 53 is stopped. Thus, since the drive gear train 70 has the lever 73 c, the control unit 90 switches the rotation direction of the motor 80, so that the rotation of the motor 80 can be transmitted to the supply screw 53. The second state can be switched to the stirring and conveying member 58. In the present embodiment, the first drive gear 73a, the second drive gear 73b, the lever 73c, and the switching means capable of switching between the first state and the second state by the control means 90 for controlling the forward / reverse rotation of the motor 80. Is configured.

  With the above configuration, when the replenishing screw 53 is rotated to replenish toner from the sub-toner container 51 to the developing device 4, the motor 80 is rotated in the direction A1 in the drawing. Thereby, it is possible to rotate the replenishment screw 53 with the stirring and conveying member 58 stopped. When the agitating / conveying member 58 is rotated to replenish toner from the main toner container 57 to the sub-toner container 51, the agitating / conveying member 58 can be maintained with the replenishing screw 53 stopped by rotating the motor 80 in the B2 direction in the figure. Can be rotated. By selectively driving the replenishing screw 53 and the agitating / conveying member 58, toner replenishment from the main toner container 57 to the sub toner container 51 and toner replenishment from the sub toner container 51 to the developing device 4 can be made independent. The T / C ratio in the developing device 4 can be maintained stably.

  In the present embodiment, the drive transmission when the motor 80 is switched between forward and reverse rotation is described as using the support lever 73c, but the present invention is not limited to this. A one-way clutch or the like well known to those skilled in the art can also be used. In this embodiment, a single motor 80 performs a toner replenishing operation from the sub-toner container 51 to the developing device 4 and an agitating / conveying operation of the toner in the main toner container 57. It is not limited to. It is also possible to carry out the replenishing operation and the stirring / conveying operation using different driving sources.

  Here, when the operation of replenishing toner from the sub-toner container 51 to the developing device 4 in a state where the developing screw 44 and the agitation screw 45 in the developing device 4 are stopped, the replenished toner is received by a receiving hole (replenishing port). It stagnates in the vicinity of 49 and causes non-uniformity in the T / C ratio of the toner and the developer in the developing device 4. Therefore, it is desirable to perform an operation of supplying toner from the sub-toner container 51 to the developing device 4 while the developing screw 44 and the stirring screw 45 in the developing device 4 are rotating. That is, the developing screw 44 and the stirring screw 45 in the developing device 4 are reliably rotated, that is, the replenishing screw 53 is rotated during image formation, and the toner replenishing operation from the sub toner container 51 to the developing device 4 is performed. Preferably it is done.

  In the case of a small-sized image forming apparatus having a relatively small capacity of the sub toner container 51, the toner can be continuously supplied from the sub toner container 51 to the developing device 4 without supplying the toner from the main toner container 57 to the sub toner container 51. Limited amount of toner. Therefore, in such a case, it is necessary to perform toner supply from the sub toner container 51 to the developing device 4 and toner supply from the main toner container 57 to the sub toner container 51 during image formation.

  FIG. 4 shows a layout of the driving configuration of the developing device 4 and the developer replenishing device 50 at each of the image forming stations PY, PM, PC, and PK in the quadruple tandem type image forming apparatus 100. The first color, the second color, the third color and the fourth color developing device 4, the developer supply device 50, and the driving configuration thereof are the same as those shown in FIG. As shown in FIG. 4, full-color printing is possible by connecting the developing devices 4 for four colors and the developer supply device 50 in series. In the case of this system, the intermediate transfer member (intermediate transfer medium) 7 or the recording material moves in the direction of the arrow shown in the drawing, and the images of the respective colors are overlapped. The image forming operation is delayed.

  In this embodiment, the developing device 200 includes the developing device 4 as described above and the developer supply device 50 including the sub toner container 51, the main toner container 57, and the like.

[Toner forced replenishment mode]
Next, the most characteristic toner forced supply mode in this embodiment will be described.

  FIG. 7 shows the number of rotations of the replenishment screw 53 (horizontal axis) and the amount of toner conveyed to the receiving hole 49 of the developing container 41 by the replenishment screw 53, that is, the amount of toner replenishment to the developing device 4 (vertical axis). It is actual experimental data that measured the relationship. The figure assumes that the apparatus is installed (when the factory-shipped apparatus is ready to be used for the first time), the main toner container 57 is mounted from the state where the sub-toner container 51 is emptied, and toner forcible replenishment described later is performed. The measurement result when the mode is not implemented is shown.

  As can be seen from FIG. 7, the amount of replenishment toner varies greatly immediately after the start of measurement until the replenishment screw 53 is rotated about 100 revolutions. This is considered to be because the toner density in the sub toner container 51 is not sufficient. That is, in this embodiment, when the main toner container 57 is mounted, the toner falls from the main toner container 57 to the sub toner container 51 by its own weight. However, although the output result of the toner sensor 56 in the sub toner container 51 indicates the presence of toner, it is considered that the toner density in the sub toner container 51 was not sufficient.

  During the measurement of the experimental data shown in FIG. 7, every time the replenishment screw 53 is rotated a predetermined number of times, the stirring and conveying member 58 of the main toner container 57 is controlled to rotate for a predetermined time. The ratio of the drive time or rotation speed of the agitating / conveying member 58 to the rotation time or rotation speed of the replenishment screw 53 is larger than the amount of toner replenished into the developing container 41 from the receiving hole 49, and from the main toner container 57 to the sub toner container 51. The amount of toner to be replenished is set to be sufficiently large.

  In FIG. 7, after the replenishment screw 53 is rotated about 100 times, the toner replenishment amount is stable because the toner amount in the sub toner container 51 gradually increases and the toner density in the sub toner container 51 is in a stable direction. It shows that it went.

  As shown in the above experimental results, when the toner density in the sub toner container 51 is not stable, the amount of toner supplied to the developing container 41 is not stable. Further, according to the study by the present inventors, in the case of a very small image forming apparatus, the volume of the sub toner container 51 is very small, and the output value of the toner sensor 56 in the sub toner container 51 indicates the presence of toner. However, the case where the amount of toner in the sub toner container 51 is not sufficient is likely to occur.

  Therefore, in this embodiment, when the toner sensor 56 detects that there is no toner in the sub-toner container 51, the above-mentioned normal replenishment of toner from the main toner container 57 to the sub-toner container 51 by driving the agitating / conveying member 58. Aside from the replenishment mode (normal replenishment operation), when the toner density in the sub-toner container 51 is assumed to be low, by driving the stirring and conveying member 58 by a predetermined amount regardless of the detection result of the toner sensor 56, A toner forced supply mode (toner forced supply operation) in which toner is forcibly supplied from the main toner container 57 to the sub toner container 51 is provided.

  FIG. 5 shows a flowchart of the toner forced supply mode in this embodiment.

  The control unit 90 is an apparatus that is provided by an input from an input unit such as a keyboard of an operation unit included in the image forming apparatus 100 or a host device (such as a personal computer) that is communicably connected to the main body of the image forming apparatus, or automatically. It is detected that the main toner container (toner cartridge, toner bottle) 57 has been replaced (S1). For example, when the apparatus is installed, it can be detected by having a flag in a backupable memory (not shown) in the control means 90. Or it is also possible to take the structure which has a sensor which judges whether it is the time of installation. Further, the replacement of the main toner container 57 can be detected by a memory (not shown) attached to the main toner container 57. As a new / old detection method for the main toner container 57, it is possible to adopt a configuration having a sensor for new / old detection, and without using a sensor or the like, the power supply is turned OFF / ON after the absence of toner is determined, or the main toner container It is also possible to adopt a configuration in which determination is made by attaching / detaching 57.

  Then, the control unit 90 starts a toner forced supply sequence when the apparatus is installed or when the main toner container 57 is replaced (S2).

  When the toner forcible replenishment mode is started, the controller 90 starts driving the motor 80 in the direction in which the stirring / conveying member 58 in the main toner container 57 is rotated (S3). At this time, a display means such as an operation unit of the image forming apparatus 100 or a display unit (not shown) of the host device may display to the operator that toner is being replenished.

  Thus, the agitating and conveying member 58 in the main toner container 57 is driven to rotate, and the toner in the main toner container 57 is conveyed into the sub toner container 51. The control unit 90 monitors the output value of the toner sensor 56 in the sub-toner container 51 after starting the driving of the stirring and conveying member 58 in S3 (S4).

  The controller 90 stops the motor 80 after a predetermined time (m seconds) has elapsed since the detection result of the toner sensor 56 indicating the presence of toner is obtained (S8). At this time, if the display means such as the operation unit of the image forming apparatus 100 or the display unit of the host device displays that toner is being replenished, the display is stopped (terminated). Then, the control unit 90 ends the toner forced supply mode (S9).

  The predetermined time (m seconds) (that is, the predetermined driving amount of the corresponding stirring and conveying member 58) can be selected as appropriate according to the configuration of the developer supply device 50, but the toner density in the sub toner container 51 ( It is preferable to obtain the amount of toner conveyed to the developing container 41 by experiments or the like based on the toner density at which the target amount is the toner amount to be conveyed.

  If there are a plurality of developing devices 200, that is, a plurality of developer replenishing devices 50, the predetermined time from when the detection result of the toner sensor 56 indicating the presence of toner is obtained until the motor 80 is stopped is determined in S5. Depending on the shape of the sub-toner container 51 and the shape of the main toner container 57, it is variable among the plurality of developer supply devices 50. It may be different in all of the plurality of developer supply devices 50. When a plurality of developing devices 200 are provided, the normal replenishment mode and the forced replenishment mode can be performed independently by each developing device 200.

  If the toner sensor 56 does not detect the presence of toner in the determination of S4, the control unit 90 monitors the duration of the detection result of the toner sensor 56 indicating the absence of toner (S6), and the predetermined time (n seconds) ) After the elapse, it is determined that there is no toner in the main toner container 57 (S7). At this time, the operator is notified of the absence of toner on display means such as the operation unit of the image forming apparatus 100 or the display unit of the host device.

  The predetermined time (n seconds) (that is, the predetermined driving amount of the corresponding stirring and conveying member 58) can be appropriately selected according to the configuration of the developer supply device 50. However, the toner density in the sub toner container 51 ( It is preferable to obtain the amount of toner conveyed to the developing container 41 by experiments or the like based on the toner density at which the target amount is the toner amount to be conveyed.

  Here, when a plurality of developer replenishing devices are provided (for each of the plurality of color developing devices), the predetermined time (time-out time) for determining the absence of toner in the determination of S6 is the sub toner container 51, the main toner container It is variable among the plurality of developer supply devices 50 in accordance with the capacity and shape of 57. It may be different in all of the plurality of developer supply devices 50.

  Next, the execution timing of the toner forced supply mode will be further described.

  As described above, the timing at which the toner density in the sub-toner container 51 is assumed to be low includes when the apparatus is installed. That is, when toner supply from the main toner container 57 to the sub toner container 51 is started in a state where the sub toner container 51 is substantially empty, it is assumed that the toner density in the sub toner container 51 becomes low.

  The timing at which the toner density in the sub-toner container 51 is assumed to be low is when the main toner container (cartridge, toner bottle) 57 is replaced. That is, after the main toner container 57 is substantially emptied and the toner supply from the main toner container 57 to the sub toner container 51 is stopped (further, the toner in the sub toner container 51 is consumed for a while), then the main toner When toner supply from the container 57 to the sub toner container 51 is resumed, it is assumed that the toner density in the sub toner container 51 becomes low.

  When the apparatus is installed, the apparatus is provided with the sub-toner container 51 empty. Therefore, when the main toner container 57 is mounted, if the toner does not move to the sub toner container 51, the sub toner container 51 needs to be filled with toner. Further, as described above, even when the toner is dropped and conveyed by its own weight when the main toner container 57 is mounted, the toner density in the sub toner container 51 is not always stable. It is necessary to transport toner.

  The replacement of the main toner container 57 is the same as when the apparatus is installed. As described above, the toner is consumed as the image is formed. When the toner sensor 56 does not detect the presence of toner even if the stirring and conveying member 58 of the main toner container 57 is rotated for a sufficient time, the toner is supplied to the sub toner container 51. Is not replenished, that is, it is determined that the main toner container 57 has run out of toner. Therefore, when the main toner container 57 is replaced, the powder level of the toner in the sub toner container 51 is lower than the toner sensor 56. In such a case, the toner density in the main toner container 51 tends to be low. Therefore, it is necessary to perform the toner forced supply mode.

  FIG. 6 shows the rotation speed (horizontal axis) of the replenishment screw 53 and the amount of toner conveyed to the receiving hole 49 of the developing container 41 by the replenishment screw 53 when the forced toner replenishment mode of the present embodiment is performed, that is, The experimental data which measured the relationship with the amount of toner replenishment (vertical axis) are shown. This measurement data was obtained by the same experiment as the measurement data shown in FIG. 7 except that the forced toner supply mode according to the present invention was performed.

  From FIG. 6, it can be seen that the toner replenishment amount is stabilized immediately after the start of measurement by performing the toner forced replenishment mode according to the present embodiment.

  As described above, when the toner density in the sub toner container 51 is assumed to be lowered when the apparatus is installed or when the main toner container 57 is replaced, the toner density in the sub toner container 51 is implemented. As a result, the amount of toner conveyed to the developing container 41 can be stabilized, and the image density can be stabilized. In other words, in order to stabilize the toner density in the sub toner container 51, when the toner density in the sub toner container 51 is considered to be low, such as when the apparatus is installed or the main toner container 57 is replaced, the output of the toner sensor 56 is output. Regardless of the value, the forced toner supply mode is executed. In particular, in a small image forming apparatus, in a configuration in which the capacity of the sub toner container 51 is small, the toner density in the sub toner container 51 can be stabilized and the image density can be stabilized.

  As described above, according to the present embodiment, it is possible to further stabilize the supply of the developer to the developing device 4.

  As mentioned above, although this invention was demonstrated according to the specific Example, it should be understood that this invention is not limited to the aspect of the said Example. For example, in the above embodiment, the first replenishing means is a screw member (conveying screw 53) having a helical conveying portion on the rotation shaft, and the second replenishing means is a blade-like shape that rotates around the rotation shaft. Although the sheet material (stirring conveyance member 58) has been described as being a sheet material, the present invention is not limited to this. The first replenishing means may be any available means that can transport the required amount of toner to the developing device 4, preferably quantitatively, and replenish the developing device 4. Further, the second replenishing means may be any available means that can transport the developer in the second container toward the supply port for supplying the developer to the first container. For example, a system in which a spiral protrusion is provided on the inner wall of the container and the container itself is rotated may be used.

  In the above embodiment, the image forming apparatus is described as a four-tandem full-color image forming apparatus. However, the number of image forming stations (that is, developing devices and developer replenishing devices) may be larger. May be fewer. Alternatively, the present invention is equally applicable to an image forming apparatus including a single image carrier, a developing device and a developer replenishing device provided correspondingly. It may be an image forming apparatus in which a plurality of developing devices are provided for a single image carrier, and a developer replenishing device is provided for each developing device. For example, as is well known to those skilled in the art, an electrostatic image that is sequentially formed on a single image carrier is developed using a developer that includes developers of different colors, and the developer image is recorded. There is an image forming apparatus of a type in which a color image is obtained by transferring sequentially or collectively to a material, or sequentially transferring to an intermediate transfer member, superimposing, transferring to a recording material, and then fixing. The present invention is equally applicable to such an image forming apparatus.

  Further, in the above-described embodiment, the description has been made assuming that toner is supplied from the developer supply device to the developing device, but the present invention is not limited to this. In a developing device adopting a two-component developing method, a carrier may be supplied together with toner. Thus, the present invention is equally applicable even when toner and carrier are replenished. The present invention is equally applicable to the case where a one-component developer substantially consisting of toner is used as the developer.

1 is a cross-sectional view of an embodiment of an image forming apparatus to which the present invention can be applied. 1 is a side sectional view of an embodiment of a developing device and a developer supply device to which the present invention can be applied. FIG. 3 is a schematic diagram illustrating an example of a driving configuration of a developer supply device and a developing device. FIG. 4 is a schematic diagram illustrating a driving configuration of a plurality of developing devices and a developer supply device in a four-tandem image forming apparatus. FIG. 10 is a flowchart of a toner forced supply mode. FIG. 6 is a graph showing the relationship between the rotation speed of a replenishing screw and the amount of toner replenishment when a toner forced replenishment mode is performed. FIG. 6 is a graph showing the relationship between the rotation speed of a replenishment screw and the amount of toner replenishment when the toner forced replenishment mode is not performed.

Explanation of symbols

1 Photosensitive drum (image carrier, electrophotographic photosensitive member)
2 Charging roller (charging means)
3 Exposure equipment (exposure means)
4 Developer 5 Primary transfer roller (transfer means)
6 Cleaning device (cleaning means)
41 Developing container 49 Receiving hole 51 Sub-toner container (first container)
53 Supply screw (first supply means)
54 Replenishing screw drive means 56 Toner sensor (detection means)
57 Main toner container (second container)
58 Stirring conveying member (second supply means)
59 Agitating and conveying member driving means 60 Toner supply port 70 Drive gear train 80 Motor 100 Image forming apparatus 200 Developing apparatus

Claims (15)

A developer that develops an electrostatic image using a developer, a first container that stores developer to be replenished to the developer, and a developer that is discharged from the first container and replenished to the developer. A first supply means; a second container for storing the developer to be supplied to the first container; and a second supply for discharging the developer from the second container and supplying the developer to the first container. An image forming apparatus comprising: a detecting unit configured to detect a developer in the first container;
A normal replenishment mode in which the second replenishing unit is driven to replenish the developer in the first container when the detecting unit detects that the developer in the first container is less than a predetermined amount. When,
A forced replenishment mode for replenishing developer to the first container by driving the second replenishment means regardless of the detection result of the detection means;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the forced supply mode is performed when the developer is supplied to the first container from a state where the first container is substantially empty.   3. The image forming apparatus according to claim 1, wherein the forced supply mode is performed when the apparatus is installed.   The forced supply mode is when the supply of the developer to the first container is resumed after the second container is substantially emptied and the supply of the developer to the first container is stopped. The image forming apparatus according to claim 1, 2, or 3.   5. The apparatus according to claim 1, wherein the second container is detachable from the main body of the image forming apparatus, and the forced replenishment mode is performed immediately after replacement of the second container. The image forming apparatus described.   The image forming apparatus according to claim 1, wherein the first supply unit and the second supply unit are selectively driven by a common or separate drive source.   In the forced replenishment mode, after the start of driving of the second replenishing unit, the second unit is detected, and after the elapse of a predetermined time after the detecting unit detects that the developer in the first container is more than a predetermined amount, The image forming apparatus according to claim 1, wherein driving of the supply unit is stopped.   In the forced replenishment mode, when the detection unit does not detect that the developer in the first container exceeds a predetermined amount even after a predetermined time has elapsed after the second replenishing unit starts to be driven, The image forming apparatus according to claim 1, wherein the driving of the second supply unit is stopped.   Further, in the forced replenishment mode, when the detection unit does not detect that the developer in the first container exceeds a predetermined amount even after a predetermined time has elapsed after the second replenishing unit starts to be driven. The image forming apparatus according to claim 8, wherein the fact that there is no developer in the second container is notified.   Each having a first and a second developing device each including the developing unit, the first container, the first replenishing means, the second container, the second replenishing means, and the detecting means; The image forming apparatus according to claim 1, wherein the normal supply mode and the forced supply mode can be performed independently by the first and second developing devices.   In the forced replenishment mode, after the start of driving of the second replenishing unit, the second unit is detected, and after the elapse of a predetermined time after the detecting unit detects that the developer in the first container is more than a predetermined amount, 11. The image forming apparatus according to claim 10, wherein driving of the replenishing means is stopped.   In the forced replenishment mode, when the detection unit does not detect that the developer in the first container exceeds a predetermined amount even after a predetermined time has elapsed after the second replenishing unit starts to be driven, 12. The image forming apparatus according to claim 10, wherein the driving of the second supply means is stopped.   Further, in the forced replenishment mode, when the detection unit does not detect that the developer in the first container exceeds a predetermined amount even after a predetermined time has elapsed after the second replenishing unit starts to be driven. The image forming apparatus according to claim 12, wherein the fact that there is no developer in the second container is notified.   14. The image forming apparatus according to claim 11, wherein the predetermined time is variable between the first developing device and the second developing device.   The image forming apparatus according to claim 1, wherein when the forced supply mode is started, the fact that the forced supply mode is being implemented is notified.

Images