JP2018072410A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can accurately determine if a recovery part is filled with developer and cause the recovery part to recover a large amount of developer.SOLUTION: An image forming apparatus comprises: a recovery toner container 8 that recovers a toner removed from the surfaces of photoreceptor drums 11; conveying means that convey the toner to the recovery toner container 8 by a fixed amount, the conveying means consisting of a first conveying screw 1 and a second conveying screw 2, where the amount of toner conveyed per unit time is reduced on the downstream in a conveyance direction compared with the upstream; and a control part 20 that determines that the recovery toner container 8 is filled with toner on the basis of the amount of toner conveyed by the conveying means to the recovery toner container 8.SELECTED DRAWING: Figure 11

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer (for example, a laser beam printer or an LED printer), and more particularly to a technique for collecting toner discharged in the image forming process.

  In an electrophotographic image forming apparatus, a toner as a developer is formed on an electrostatic latent image formed on the surface of a photosensitive drum to form a toner image, and the toner image is transferred to a recording medium to form an image. To do. On the other hand, after the transfer, the toner remaining on the photosensitive drum or the intermediate transfer belt as an image carrier is removed by a cleaning member, and the removed toner is collected in a collected toner container (collecting unit).

  Here, the collected toner container needs to be replaced when the inside of the container is filled with the collected toner. In recent years, as the productivity of image forming apparatuses has improved, the amount of toner collected per unit time has been increasing. To reduce the frequency of replacement of the collected toner container, the capacity of the collected toner container has increased. Progressing. However, there is a space limitation in increasing the capacity of the collected toner container, and it is required to collect more toner with a limited capacity.

  Therefore, conventionally, a configuration for collecting a large amount of toner in a collected toner container has been proposed. For example, in Patent Document 1, the amount of toner collected in a collected toner container is predicted according to pixel information and usage status. Thus, a configuration is described in which the toner amount prediction accuracy is improved and a large amount of toner is collected in a collected toner container.

  In Patent Document 2, the toner is retained in the buffer container before the toner is collected in the collected toner container, and the toner volume is detected by the detection unit provided in the buffer container. Thereafter, the volume of toner detected by the buffer container is transported to the collected toner container, and the fullness of the toner in the collected toner container is determined based on the number of times of transport to the collected toner container. With such a configuration, a larger amount of toner can be collected in the collected toner container than in the configuration in which the toner amount is detected inside the collected toner container.

JP 2010-127989 A JP 2014-21471 A

  However, in the configuration of Patent Document 1, only the prediction accuracy of the amount of collected toner is improved, and the transfer efficiency cannot be estimated accurately, so it is difficult to accurately determine fullness.

  Further, in the configuration of Patent Document 2, the toner retained in the buffer container has more charge than the toner in the state where the toner is left in the collected toner container and discharged in the air. For this reason, the bulk density of the toner whose volume is measured in the buffer container is lower than the bulk density of the toner in the recovered toner container. Therefore, the toner temporarily staying in the buffer container is left in the recovered toner container, the bulk density is increased, and the volume is changed small. As a result, in the configuration of Patent Document 2, since the toner amount is controlled based on the toner volume in the buffer container, the toner volume changes in the recovered toner container so that a toner accumulation space is formed in the recovered toner container. Nevertheless, it is determined that the collected toner container is full.

  Accordingly, the present invention has been made in view of such a current situation, and provides an image forming apparatus capable of accurately determining the fullness of the developer in the collection unit and allowing the collection unit to collect a large amount of developer. With the goal.

  In order to achieve the above object, an image forming apparatus according to the present invention includes a collection unit that collects developer removed from the surface of an image carrier, and a conveyance that conveys the developer to the collection unit by a certain amount. And a transport unit in which the transport amount of the developer per unit time is smaller in the downstream than in the upstream in the transport direction, and the transport amount of the developer that the transport unit transports to the recovery unit. And control means for determining that the developer in the collection unit has reached a predetermined amount.

  According to the present invention, it is possible to accurately determine the fullness of the developer in the collection unit, and to collect a large amount of developer in the collection unit.

1 is a schematic cross-sectional view of an image forming apparatus. FIG. 3 is a schematic cross-sectional view of a toner recovery mechanism. It is the cross-sectional schematic of the upper surface direction of a buffer container. It is the cross-sectional schematic of the front direction of a buffer container. It is the cross-sectional schematic of the final conveyance part of another structure. It is the cross-sectional schematic of the final conveyance part of another structure. It is the cross-sectional schematic of the final conveyance part of another structure. It is the cross-sectional schematic of the final conveyance part of another structure. It is the cross-sectional schematic of a final conveyance part. 2 is a block diagram illustrating a partial configuration of a control system of the image forming apparatus. FIG. 10 is a flowchart of a collected toner container full determination sequence. FIG. 3 is a schematic cross-sectional view of a buffer container and a collected toner container. FIG. 10 is a schematic cross-sectional view of another configuration of a buffer container and a recovered toner container. FIG. 3 is a schematic cross-sectional view of a buffer container and a collected toner container. 10 is a flowchart of a collected toner container full determination sequence.

(First embodiment)
<Image forming apparatus>
First, the overall configuration of the image forming apparatus according to the first embodiment of the present invention will be described with reference to the drawings together with the operation during image formation. Note that the dimensions, materials, shapes, relative arrangements, and the like of the described components are not intended to limit the scope of the present invention only to those unless otherwise specified.

  The image forming apparatus A transfers four color toners (developers) of yellow Y, magenta M, cyan C, and black K to an intermediate transfer belt, and then transfers the image to a sheet (recording material) to form an image. This is an intermediate transfer tandem type and electrophotographic color image forming apparatus. In the following description, although the members using the toners of the respective colors are given subscripts Y, M, C, and K, the configuration and operation of each member are different except that the color of the toner used is different. Since they are substantially the same, subscripts are omitted as appropriate unless distinction is required.

  As shown in FIG. 1, the image forming apparatus A includes an image forming unit that transfers a toner image to a sheet, a sheet feeding unit that supplies the sheet to the image forming unit, a fixing unit that fixes the toner image on the sheet, Is provided.

  The image forming unit includes a photosensitive drum 11 (11Y, 11M, 11C, 11K) as an image carrier arranged in series in a horizontal portion of the intermediate transfer belt 31, and a charging roller for charging the photosensitive drum 11. 12 (12Y, 12M, 12C, 12K). Further, a cleaning blade 15 (15Y, 15M, 15C, 15K), a laser scanner unit 13 (13Y, 13M, 13C, 13K), a developing device 14 (14Y, 14M, 14C, 14K), and an intermediate transfer unit 30 are provided.

  The intermediate transfer unit 30 includes a primary transfer roller 35 (35Y, 35M, 35C, and 35K), an endless cylindrical intermediate transfer belt 31 (image carrier), a secondary transfer roller 41, a secondary transfer counter roller 32, and a cleaning device 101. Etc. The intermediate transfer belt 31 is stretched by a secondary transfer counter roller 32, a driving roller 33, and a tension roller 34, and rotates by receiving a driving force from the driving roller 33.

  Next, an image forming operation will be described. First, when the control unit 20 shown in FIG. 10 receives the image forming job signal, the sheets S stacked and stored in the sheet feeding cassettes 61 (61a to 61d) are conveyed to the sheet conveying path 81 by the feeding rollers 74 (74a to 74d). Thereafter, the sheet S is conveyed to the registration roller 75. The registration roller 75 conveys the sheet S to the image forming unit after matching the operation and timing of the image forming unit.

  On the other hand, in the image forming unit, first, the surface of the photosensitive drum 11 is charged by the charging roller 12. Thereafter, the laser scanner unit 13 irradiates the surface of the photosensitive drum 11 with laser light in accordance with an image signal transmitted from an external device (not shown) or the like, thereby forming an electrostatic latent image on the surface of the photosensitive drum 11. A toner image is formed on the photosensitive drum 11 by developing the electrostatic latent image with the developing device 14 by attaching toner.

  The toner image formed on the photosensitive drum 11 is applied to the intermediate transfer belt 31 by applying a primary transfer bias to the primary transfer roller 35 in a primary transfer portion formed by the photosensitive drum 11 and the primary transfer roller 35. Each is primary transferred.

  Thereafter, the toner image is sent to the secondary transfer portion formed by the secondary transfer roller 41 and the secondary transfer counter roller 32 by the rotation of the intermediate transfer belt 31. In this secondary transfer portion, a secondary transfer bias is applied to the secondary transfer roller 41, whereby the toner image on the intermediate transfer belt 31 is transferred to the sheet S.

  The sheet S to which the toner image has been transferred is sent to the fixing device 90 and heated and pressed to fix the toner image on the sheet S. Then, the sheet S passes through the paper discharge conveyance path 82, the reverse conveyance path 83, and the buffer conveyance path 84. It is discharged to the discharge tray 65 through.

  Further, the toner remaining on the photosensitive drum 11 after the primary transfer is scraped off by the cleaning blade 15 and removed. Similarly, the toner remaining on the intermediate transfer belt 31 after the secondary transfer is scraped off by the cleaning device 101 and removed.

<Toner recovery mechanism>
Next, an outline of a configuration of a toner recovery mechanism that recovers toner generated by the image forming process will be described.

  FIG. 2 is a schematic cross-sectional view of the toner recovery mechanism. As shown in FIG. 2, the toner on the photosensitive drum 11 scraped off by the cleaning blade 15 first accumulates in the first cleaning container 16 (16Y, 16M, 16C, 16K). Thereafter, the first cleaning container 16 is transported in the direction of the rotation axis of the photosensitive drum 11 by a transport screw (not shown) and transported to the vertical pipe 203. The deteriorated toner generated in the developing device 14 is also conveyed to the vertical pipe 203.

  Similarly, the toner on the intermediate transfer belt 31 scraped off by the cleaning device 101 is also temporarily accumulated in the second cleaning container 36 and then conveyed to the vertical pipe 202.

  The toner conveyed to the vertical pipes 202 and 203 in this way passes through the vertical pipes 202 and 203 and merges in the horizontal pipe 204, and is conveyed to the discharge pipe 201 by the conveyance screw 205 disposed in the horizontal pipe 204. Is done. Thereafter, the toner that has passed through the discharge pipe 201 falls into the buffer container 206 from the opening at the top of the buffer container 206 as a staying portion, and is accumulated and stored.

  The toner temporarily retained in the buffer container 206 passes through a final transport unit 208 disposed under the buffer container 206 and then passes through a recovery pipe 209 to be recovered in a recovery toner container 200 as a recovery unit. Is done.

  The collected toner container 8 is configured to be detachable from the main body of the image forming apparatus A (image forming apparatus main body). When the toner in the collected toner container 8 becomes full, the user replaces it with a new collected toner container 8. . Further, the main body of the image forming apparatus A is provided with a collected toner container presence / absence detection unit 210 that detects that the collected toner container 8 is mounted.

<Residual part>
Next, the configuration of the buffer container 206 as a staying part for temporarily retaining the toner collected in the collected toner container 8 will be described.

  3 is a schematic cross-sectional view of the buffer container 206 in the upper surface direction, and FIG. 4 is a schematic cross-sectional view of the buffer container 206 in the front direction. As shown in FIGS. 3 and 4, the buffer container 206 includes a deposition space 220 for temporarily retaining toner, and a final transport unit 208 for transporting the toner in the buffer container 206 to the collected toner container 8. Yes.

  Further, a powder level detection unit 221 (detection unit) for detecting the amount of toner (developer amount) in the buffer container 206 is attached to the side surface of the buffer container 206. The powder level detection unit 221 is turned on when the toner powder level in the buffer container 206 is higher than the detection surface of the powder level detection unit 221. Further, a uniformizing member 222 is provided for uniformizing the powder surface of the toner in the buffer container 206. The toner dropped from the discharge pipe 201 is accumulated in the accumulation space 220, and the powder level is made uniform by the uniformizing member 222 being rotated by a rotation driving unit (not shown).

  The final transport unit 208 includes a first transport path 3 in which the first transport screw 1 is disposed and a second transport path 4 in which the second transport screw 2 is disposed. The first transport path 3 has an opening 5 for connecting the first transport path 3 and the second transport path 4. The first conveying screw 1 and the second conveying screw rotate to convey toner by means of spiral blades provided on the rotation shaft. The second conveying screw 2 is disposed on the downstream side of the first conveying screw in the toner conveying direction. Further, the final transport unit 208 includes a drive unit 25 (see FIG. 10) that drives the first transport screw 1 and the second transport screw 2.

  The outer diameter of the first conveying screw 1 is 16 mm, the shaft diameter is 6 mm, the blade pitch is 11.5 mm, and the diameter of the first conveying path 3 is 18 mm. The outer diameter of the second conveying screw 2 is 13 mm, the shaft diameter is 6.8 mm, the blade pitch is 9 mm, and the diameter of the second conveying path 4 is 14.5 mm. Moreover, the 1st conveyance screw 1 and the 2nd conveyance screw 2 are driven by the same drive source, the gear ratio is 2.1, and the 1st conveyance screw 1 is 2. rather than the 2nd conveyance screw 2. The 1-time rotation speed is fast. With the above configuration, the toner conveyance amount per rotation of the screw is 1.66 [ml] for the first conveyance screw 1 and 1.43 [ml] for the second conveyance screw 2.

  With such a configuration, the toner conveyance amount per unit time is smaller in the second conveyance screw 2 than in the first conveyance screw 1. That is, in the final transport unit 208, the toner transport amount per unit time is smaller downstream than upstream in the transport direction. Therefore, in the final transport unit 208, the toner is transported to the collected toner container 8 while being compressed.

  By compressing the toner in this way, the charge of the toner is removed. For this reason, the bulk density of the toner conveyed from the final conveyance unit 208 to the collected toner container 8 and the toner left in the collected toner container 8 and discharged in the air can be made close to each other.

  In addition, as a configuration for conveying toner while compressing, the following configuration is conceivable. That is, for example, as shown in FIG. 5, a configuration in which the diameter of the rotating shaft of the first conveying screw 1 is smaller than the diameter of the rotating shaft of the second conveying screw 2 can be considered. In addition, as shown in FIG. 6, a configuration in which the diameters of the blades of the first conveyance path 3 and the first conveyance screw 1 are larger than the diameters of the blades of the second conveyance path 4 and the second conveyance screw 2 is also conceivable.

  Further, when the shaft diameter, the diameter, and the screw pitch of the first conveying screw 1 and the second conveying screw 2 are matched, and the diameters of the first conveying path 3 and the second conveying path 4 are matched, A configuration in which the rotational speed is faster than the rotational speed of the second conveying screw 2 is also conceivable. Moreover, when the drive part of the 1st conveyance screw 1 and the drive part of the 2nd conveyance screw 2 are drive separately, the structure which drives the 1st conveyance screw 1 continuously and drives the 2nd conveyance screw 2 intermittently can also be considered. .

  Furthermore, in order to convey the toner while compressing it, it is not always necessary to constitute the toner with a plurality of conveying screws, and it may be constituted with one conveying screw. In this case, for example, as shown in FIG. 7, the diameter of the rotating shaft increases from the upstream to the downstream in the conveying direction of the second conveying screw 2, or the blades from the upstream to the downstream in the conveying direction as shown in FIG. A configuration in which the pitch is reduced is conceivable.

  Furthermore, a combination of the configurations exemplified above may be used. In the process of transporting toner from the buffer container 206 to the collected toner container 8, the transport amount of toner per unit time becomes smaller downstream than upstream in the transport direction. I just need it. However, if the toner is compressed too much, there is a concern about overloading the conveying screw. Therefore, it is preferable to set the compression ratio to about 1.16, which is equivalent to the compression ratio in the present embodiment.

  Next, a configuration for conveying the compressed toner to the collected toner container 8 by a certain amount will be described.

  FIG. 9 is a schematic cross-sectional view of the final transport unit 208. As shown in FIG. 9, the toner conveyed while being compressed by the first conveying screw 1 and the second conveying screw 2 falls from the opening at the top of the collecting pipe 209 and is collected in the collecting toner container 8.

  Here, when the toner is transported in the state where the second transport path 4 is filled with toner, if the second transport screw 2 is rotated once, the volume corresponding to one pitch of the blades of the second transport screw 2 (Vp shown in FIG. 9). ) Is conveyed to the collected toner container 8. Therefore, by driving the second conveyance screw 2 in a state where the second conveyance path 4 is filled, the toner is collected in the collected toner container 8 by a certain amount (a certain volume) according to the number of rotations of the second conveyance screw 2. Can be transported. Therefore, the amount of toner conveyed to the collected toner container 8 can be controlled according to the number of rotations of the second conveyance screw 2. Hereinafter, the conveyance of a constant amount of toner to the collected toner container 8 in a state where the second conveyance path 4 is full will be referred to as quantitative discharge.

  When the fixed amount is discharged, the second conveying screw 2 is driven in a state where the second conveying path 4 is filled with the toner. Therefore, the first conveying screw 1 and the second conveying screw 2 have the powder level detection unit 221 turned on. Thus, the driving is started when the toner in the buffer container 206 reaches a predetermined level or more. As a result, the driving of the second conveying screw 2 is started in the state where the final conveying unit 208 is filled with toner, that is, the first conveying path 3 and the second conveying path 4 are filled with toner, and the compressed toner is discharged quantitatively. can do.

<Control unit>
Next, the configuration of the control unit of the image forming apparatus A, particularly the configuration of the control unit related to the toner recovery mechanism will be described.

  FIG. 10 is a block diagram illustrating a partial configuration of the control system of the image forming apparatus A. As illustrated in FIG. 10, the image forming apparatus A includes a control unit 20 that performs various controls. The control unit 20 includes a memory 22, a drive control unit 23, and a calculation unit 24.

  The calculation unit 24 performs calculations necessary for various controls. The memory 22 stores setting values and the like necessary for various controls, and is called by the control unit 20 as necessary. The drive control unit 23 controls the drive unit 25 that drives the first conveyance screw 1 and the second conveyance screw 2.

  Further, a powder level detection unit 221 and a collected toner container presence / absence detection unit 210 are connected to the control unit 20. For this reason, the control unit 20 can control the drive unit 25 and the like based on the detection results of the powder level detection unit 221 and the collected toner container presence / absence detection unit 210.

  The control unit 20 is connected to an operation panel 21 (notification means). The user can execute an image forming job by operating the operation panel 21, and the control unit 20 operates various devices of the image forming apparatus A in response to a signal from the operation panel 21. Various information is displayed on the operation panel 21.

<Recovered toner container full determination sequence>
Next, a collected toner container full determination sequence for determining whether the collected toner container 8 is full with the above-described configuration will be described with reference to the flowchart shown in FIG.

  First, when the sequence is started, the control unit 20 determines whether or not the collected toner container 8 is replaced (S1). This determination may be performed by a method in which the user operates the operation panel 21 to complete the replacement of the collected toner container 8, or a new / old detection unit is provided in the collected toner container 8, and the new / old detection unit of the collected toner container 8 is provided on the apparatus body side. And a method of determining the presence or absence of replacement based on the detection result.

  Next, when the collected toner container 8 is replaced and it is determined that a new collected toner container 8 is contained, it is determined whether the total rotation number NA of the second conveying screw 2, the number of image formations NB, and driving of the conveying screw 2 are stopped. The value of the flag F to be reset is reset (S2).

  Next, the collected toner container presence / absence detecting unit 28 detects whether or not the collected toner container 8 is attached to the main body of the image forming apparatus A (S3), and if so, the total rotation of the second conveying screw 2 is detected. It is determined whether the number NA is less than the permissible rotational speed NA-MAX (S4). This allowable rotational speed NA-MAX is calculated as follows. That is, the volume of the collected toner container 8 that can be accumulated in the collected toner container 8 is V [L], and the volume of toner (1) that is conveyed to the collected toner container 8 when the second conveying screw 2 rotates once. Let Vp [L] be the pitch). At this time, the allowable number of rotations NA-MAX is the number of times the second conveying screw 2 can be rotated from when the new collected toner container 8 is mounted to when the collected toner container 8 becomes full, and NA-MAX = V / Vp. It is represented by The number of rotations is a natural number.

  Here, when it is determined that the total rotational speed NA is less than the allowable rotational speed NA-MAX, the collected toner container 8 is not full. Therefore, the control unit 20 next determines whether the powder level of the toner in the buffer container 206 is less than the height of the powder level detection unit 221 by the powder level detection unit 221 (S5). If the powder level detection unit 221 is not ON, the final conveyance unit 208 is not filled with toner, so the first conveyance screw 1 and the second conveyance screw 2 are not driven, and the process returns to step S1 and repeats the above steps. .

  At the time of image formation, toner is always dropped into the buffer container 206. Accordingly, when the image forming operation is continued, the powder level of the toner comes above the powder level detection unit 221 and the powder level detection unit 221 is turned on. When determining that the powder level detection unit 221 is ON (S5), the control unit 20 checks the flag F (S6). If the flag F is not set, the first conveyance screw 1 and the second conveyance screw 2 are checked. Is rotated 40 times (S7). As a result, the toner having a volume corresponding to 40 revolutions of the second conveying screw 2 is conveyed to the collected toner container 8. Thereafter, 40 rotations are added to the total rotation number NA of the second conveying screw 2 (S8), and the process returns to step S1 again.

  It should be noted that the value of 40 rotations is higher than the final conveyance unit 208 when the toner of the volume corresponding to 40 rotations of the second conveyance screw is conveyed to the collected toner container 8 after the powder level detection unit 221 is turned on. This is the number of rotations that guarantees that there is a powder surface of the toner. The number of rotations is not limited to 40 as long as the number of rotations guarantees that the toner powder surface is above the final conveyance unit 208 while the second conveyance screw 2 is being driven.

  When such a process is repeated, the total rotation number NA of the second conveying screw 2 increases, and toner accumulates in the collected toner container 8. When the total number of revolutions NA and the allowable number of revolutions NA-MAX match, the control unit 20 determines that the collected toner container 8 is full (the developer in the collecting unit is a predetermined amount or more) (S4). When determining that the collected toner container 8 is full, the control unit 20 causes the operation panel 21 to display a message indicating that the collected toner container 8 is full and a replacement request message (S9). Further, a flag F for determining whether or not the second feed screw 2 is stopped is set (S10).

  According to the configuration described above, the toner is compressed to remove the electric charge of the toner, and the bulk density of the toner conveyed to the collected toner container 8 and the toner left in the collected toner container 8 is made closer and compressed. The toner can be conveyed to the collected toner container 8 by a certain amount. By controlling the amount of toner in the recovered toner container 8 based on the amount of toner transported to the recovered toner container 8 by the second transport screw 2, the recovery is based on the actual toner amount instead of the predicted toner amount. The toner fullness in the toner container 8 can be determined. Therefore, the fullness of the toner in the collected toner container 8 can be accurately determined, and a large amount of toner can be collected in the collected toner container 8.

  Next, the control after determining that the collected toner container 8 is full will be described.

  After determining that the collected toner container 8 is full, the control unit 20 determines again whether or not the powder level detection unit 221 is ON (S5). Thereafter, the same process is repeated until the powder level detection unit 221 is turned on and the powder level of the toner in the buffer container 206 reaches the level of the powder level detection unit 221 (S1 to S5, S9, S10).

  Next, when it is determined that the powder level detection unit 221 is ON, the control unit 20 checks the flag F (S6). Here, the flag F has already been set in step S10. For this reason, it determines with it not being F = 0, and moves to the following step S11.

  In step S11, it is determined whether or not the image forming number NB has reached the allowable image forming number NB-MAX. The allowable image forming number NB-MAX will be described. First, the toner is conveyed to the buffer container 206 based on the volume information of the toner used in the image forming process, the amount G of image forming toner, the amount of toner P for control, the amount of toner H for image stabilization, and the expected transfer efficiency Kp. The predicted value Vt of the toner volume is calculated by the following equation 1. Here, the image forming toner amount G is a volume of toner used for image formation of a toner image formed based on image information designated by the user. The control toner amount P is a volume of toner used for forming a patch image when forming a patch image and performing control for adjusting the color of the image at the time of image formation from the density of the patch image. The image stabilizing toner amount H is a volume of deteriorated toner discharged from the developing device 14 through the vertical pipe 203.

  Vt = G × Kp + P + H (1)

  The number of image formations when the predicted value Vt calculated in this way matches the volume of the space in the buffer container 206 where toner can be accumulated is defined as an allowable image formation number NB-MAX. Here, when the image forming number NB does not reach the allowable image forming number NB-MAX, it is predicted that the buffer container 206 is not filled with toner. That is, in step S6, although it is detected that the powder surface height of the toner in the buffer container 206 is equal to or higher than the powder surface detection unit 221, the space above which toner can be accumulated (shaded portion in FIG. 12). It is predicted that all will not be filled with toner. Therefore, one image is added to the image forming number NB (S12), and the flag F is reset (S13). Thereafter, returning to step 1, image formation is performed until the image formation number NB and the allowable image formation number NB-MAX match.

  If the image forming number NB matches the allowable image forming number NB-MAX (S11), it is predicted that the buffer container 206 is filled with toner. Therefore, in order to prevent the toner from overflowing from the buffer container 206, image formation is stopped (S15), and the sequence is terminated.

  In step S11, a second powder level detection unit may be provided in the buffer container 206, and image formation may be stopped based on the detection result. That is, as shown in FIG. 13, the second powder level detection unit 224 is provided in the vicinity of the uppermost part of the space where toner above the powder level detection unit 221 can be accumulated. When the toner powder level reaches the height of the second powder level detection unit 224, it is determined that the buffer container 206 is filled with toner, and image formation is stopped. As a result, the image formation can be stopped based on the actual toner amount based on the powder level detection instead of the predicted toner amount, and the image formation can be stopped at a more accurate timing.

  If the collected toner container 8 is not attached to the main body of the image forming apparatus A (S3), a message for requesting attachment of the collected toner container 8 is displayed on the operation panel 21 (S9), and the flag F is set (S10). ), The same control as that after the collected toner container 8 is determined to be full is performed.

(Second Embodiment)
Next, a second embodiment of the image forming apparatus A according to the present invention will be described with reference to the drawings. The same parts as those in the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted.

  In the first embodiment, the powder level detector is disposed in the buffer container 206. In the present embodiment, as shown in FIG. 14, the powder level detection unit 300 is not arranged in the buffer container 206 but the powder level detection unit 300 is arranged in the collected toner container 8.

  Hereinafter, the recovery toner container full determination sequence of this embodiment will be described with reference to the flowchart shown in FIG.

  As shown in FIG. 15, first, similarly to the sequence of the first embodiment, it is determined whether or not the collected toner container 8 is replaced (S51). If the recovered toner container 8 is replaced, the total rotation number NA of the second conveying screw 2 is determined. The values of the image forming number NB, the flag F, and the flag Fa are reset (S52). The flag Fa will be described later.

  Next, it is detected whether or not the collected toner container 8 is attached (S53). If the collected toner container 8 is attached, whether the toner powder level in the collected toner container 8 has reached the height of the powder level detection unit 300 or not. Whether or not the powder level detection unit 300 is ON is determined (S54).

  Here, when the toner powder level does not reach the level of the powder level detection unit 300, the first conveyance screw 1 and the second conveyance screw 2 are driven to discharge the toner to the collected toner container 8 (S55), and the final conveyance unit. In step 208, the process returns to step S1 when the toner is empty. By repeating this process, toner is accumulated in the collected toner container 8.

  Next, after the powder level detection unit 300 detects ON, the control unit 20 determines whether or not the total rotation number NA of the second conveying screw 2 is less than the allowable rotation number NA-MAX (S56). If the total rotational speed NA is less than the allowable rotational speed NA-MAX, it is determined whether or not the flag F is set (S57). If the flag F is not set, it is determined whether or not the flag Fa is set. Determine (S58).

  Next, the flag Fa will be described. As described above, since the toner continues to be discharged to the collected toner container 8 by the second conveying screw 2 until the powder level of the toner in the collected toner container 8 reaches the level of the powder level detecting unit 300, the final conveying unit 208 is empty. It is in the state of. For this reason, in order to perform quantitative discharge similarly to 1st Embodiment, it is necessary to be in the following state.

  That is, it is necessary to store in the buffer container 206 the total of the toner volume VBK that fills the final transport unit 208 and the toner volume VBT that is transported to the collected toner container 8 when the transport screw 2 rotates 40 times. In FIG. 14, the volume VBK is shown as the volume of toner deposited below the line V in the buffer container 206, and the volume VBT is shown as the volume of toner between the lines V and W. In the buffer container 206, the volume of the space where the toner above the line W can be deposited is defined as a volume VBJ.

  In addition, when the second conveying screw 2 rotates 40 times while the total amount of toner of the volume VBK and the volume VBT is accumulated in the buffer container 206, the toner volume in the toner buffer container 206 is reduced to the volume VBK. For this reason, it is necessary to store the toner of volume VBT in the buffer container 206 until the next quantitative discharge. In this way, the volume of toner that needs to be accumulated in the buffer container 206 changes from the volume VBK + volume VBT to the volume VBK at the first quantitative discharge and at the second and subsequent quantitative discharges. The flag Fa determines the difference in the volume of toner accumulated in the buffer container 206 in this way. That is, when the flag Fa is not set, it is necessary to store the volume VBK + volume VBT toner in the buffer container 206, and when the flag Fa is set, it is necessary to store the volume VBT toner in the buffer container 206. is there.

  After the collected toner container 8 is replaced, the flag Fa is not set at a stage where the fixed amount discharge has not been performed yet. Therefore, in order to determine whether or not the volume VBK + volume VBT toner remains in the buffer container 206, it is determined whether the image forming number NB is equal to or larger than the allowable image forming number NBK + NBT (S9).

  Next, the allowable image formation number NBK and NBT will be described. As described above, when the predicted value Vt of the volume of toner conveyed to the buffer container 206 during image formation matches the volume of the space in the buffer container 206 where toner can be accumulated, the number of images formed is the allowable image formation. The number of sheets is represented by NB-MAX. On the other hand, the allowable image formation number NBK is the number of image formations when the predicted value Vt and the volume VBK (see FIG. 14) match. The allowable image formation number NBT is the number of image formations when the predicted value Vt matches the volume VBT (see FIG. 14). Further, an allowable image forming number NBJ, which will be described later, is an image forming number when the predicted value Vt matches the volume VBJ (see FIG. 14).

  Here, when the image forming number NB is less than the allowable image forming number NBK + NBT, it is predicted that the toner of volume VBK + volume VBT does not stay in the buffer container 206. For this reason, 1 is added to the image forming number NB (S60), and the process returns to step S51. Thereafter, image formation is continued, and when the image formation number NB becomes equal to or greater than the allowable image formation number NBK + NBT (S59), it is determined that the toner of the volume VBK + volume VBT has accumulated in the buffer container 206, and the flag Fa is set (S61). ).

  After the flag Fa is set, the control unit 20 rotates the first transport screw 1 and the second transport screw 2 40 times (S62). As a result, a volume of toner corresponding to 40 revolutions of the second conveying screw 2 is conveyed to the collected toner container 8, while the toner powder level in the buffer container 206 is lowered from the line W to the line V shown in FIG. Thereafter, 40 rotations are added to the total rotation number NA of the second conveying screw 2 (S63), the image forming number NB is reset (S64), and the process returns to step S51.

  When the above steps are repeated and step S58 is reached again, the flag Fa is in a standing state. Therefore, it is next determined whether or not the image forming number NB is equal to or larger than the allowable image forming number NBT (S65). At this stage, the volume of the toner in the buffer container 206 is at least the volume VBK or more. In other words, the height of the toner powder surface is equal to or higher than the line V shown in FIG.

  Here, when the image forming number NB is less than the allowable image forming number NBT, the volume of the toner in the buffer container 206 is predicted to be smaller than the volume VBK + volume VBT. That is, it is predicted that the toner powder level has not reached the line W shown in FIG. For this reason, 1 is added to the image forming number NB (S60), and the process returns to step S1.

  On the other hand, when the image forming number NB is equal to or larger than the allowable image forming number NBT, the volume of the toner in the buffer container 206 is predicted to be equal to or larger than volume VBK + volume VBT. Therefore, the first conveying screw 1 and the second conveying screw 2 are rotated 40 times (S62), and the toner in the buffer container 206 is quantitatively discharged to the collected toner container 8. Thereafter, 40 rotations are added to the total rotation number NA of the second conveying screw (S63), and the process returns to Step 1.

  When such a process is repeated, the total rotation number NA of the second conveying screw 2 increases, and toner accumulates in the collected toner container 8. When the total rotational speed NA and the allowable rotational speed NA-MAX match, the control unit 20 determines that the collected toner container 8 is full (the developer in the collecting unit is a predetermined amount or more) (S56). When determining that the collected toner container 8 is full, the control unit 20 displays a message indicating that the collected toner container 8 is full and a replacement request message on the operation panel 21 (S66). Further, a flag F for determining whether or not the second feed screw 2 is stopped is set (S67).

  According to the configuration described above, the toner can be compressed to remove the charge of the toner, and the bulk density of the toner conveyed to the collected toner container 8 and the toner left in the collected toner container 8 can be made closer. Further, after the powder level detection unit 300 is turned on, the compressed toner can be conveyed to the collected toner container 8 by a certain amount. By controlling the amount of toner in the recovered toner container 8 based on the amount of toner transported to the recovered toner container 8 by the second transport screw 2, the recovery is based on the actual toner amount instead of the predicted toner amount. The toner fullness in the toner container 8 can be determined. Therefore, the fullness of the toner in the collected toner container 8 can be accurately determined, and a large amount of toner can be collected in the collected toner container 8.

  The control after determining that the collected toner container 8 is full is almost the same as the control in the first embodiment. That is, the controller 20 checks the flag F (S57), and since the flag F has already been set in step S67, the process proceeds to step S68. Thereafter, in step S68, it is determined whether or not the image formation number NB and the allowable image formation number NBT + NBJ match.

  If the image forming number NB is smaller than the allowable image forming number NBT + NBJ, it is predicted that the buffer container 206 is not filled with toner. For this reason, one image is added to the image forming number NB (S69), and the flag F is reset (S70). Thereafter, returning to step 1, image formation is performed until the image formation number NB and the allowable image formation number NBT + NBJ match.

  When the image forming number NB matches the allowable image forming number NBT + NBJ (S68), it is predicted that the buffer container 206 is filled with toner. Therefore, image formation is stopped to prevent the toner from overflowing from the buffer container 206 (S72), and the sequence is terminated.

  If the collected toner container 8 is not attached to the main body of the image forming apparatus A (S53), a message for requesting attachment of the collected toner container 8 is displayed on the operation panel 21 (S71), and the flag F is set (S67). Then, the same control as that after the collected toner container 8 is determined to be full is performed.

1 ... 1st conveyance screw (conveyance means)
2 ... Second conveying screw (conveying means)
8 ... Collected toner container (collection unit)
11 ... Photosensitive drum (image carrier)
20: Control unit 20 (control means)
21 ... Operation panel (notification means)
31. Intermediate transfer belt (image carrier)
206: Buffer container (retention part)
A: Image forming apparatus

Claims (14)

A collection unit for collecting the developer removed from the surface of the image carrier;
A transporting means for transporting the developer by a fixed amount to the recovery unit, wherein the transporting amount of the developer per unit time becomes smaller downstream than upstream in the transporting direction;
Control means for determining that the developer in the recovery unit has reached a predetermined amount based on the transport amount of the developer transported to the recovery unit by the transport unit;
An image forming apparatus comprising: A retention portion for temporarily retaining the developer removed from the surface of the image carrier,
The image forming apparatus according to claim 1, wherein the conveying unit conveys the developer staying in the staying portion to the collecting portion. The transport means includes a transport screw that is disposed in the transport path and rotates to transport the developer by a spiral blade,
The image forming apparatus according to claim 2, wherein the transport screw transports the developer to the recovery unit in a state where the transport path is filled with the developer.   The transport path is disposed in the staying portion, and the transport screw transports the developer to the collecting portion when the amount of the developer staying in the staying portion becomes a predetermined amount or more. The image forming apparatus according to 3.   The image forming apparatus according to claim 4, further comprising a detection unit that detects an amount of the developer retained in the retention unit.   The conveying screw includes a plurality of first conveying screws and a second conveying screw that is disposed on the downstream side in the conveying direction of the first conveying screw and has a lower rotational speed than the first conveying screw. The image forming apparatus according to claim 3, wherein the image forming apparatus is an image forming apparatus.   The transport screw is composed of a plurality of first transport screws and a second transport screw that is arranged downstream of the transport direction of the first transport screw and has a larger rotation shaft diameter than the first transport screw. The image forming apparatus according to claim 3, further comprising:   The conveying screw includes a plurality of first conveying screws and a second conveying screw that is disposed downstream of the first conveying screw in the conveying direction and has a blade diameter smaller than that of the first conveying screw. The image forming apparatus according to claim 3, further comprising:   The image forming apparatus according to claim 3, wherein a diameter of a rotation shaft of the conveying screw increases from upstream to downstream in a conveying direction.   The image forming apparatus according to claim 3, wherein the conveying screw has a pitch of the blades that decreases from an upstream side to a downstream side in a conveying direction. When the volume of the developer conveyed to the collection unit per rotation of the conveyance screw is Vp, the rotation number of the conveyance screw is R, and the volume of the collection unit is V,
11. The image forming apparatus according to claim 3, wherein the control unit determines that the collecting unit is full when R ≧ V / Vp.   12. The image forming apparatus according to claim 11, wherein the control unit stops conveyance of the developer by the conveyance screw when it is determined that the collecting unit is full.   13. The image forming apparatus according to claim 11, wherein the control unit causes the notification unit to notify the fullness of the recovery unit when it is determined that the recovery unit has reached full. 13.   The image forming apparatus according to claim 1, wherein the collection unit is detachable from the image forming apparatus main body.

Images