JP2017090693A - Image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation device that can sufficiently reduce the remaining quantity of toner in a toner container that has reached the end of useful life without sacrificing productivity of image formation even when a large quantity of toner is to be consumed in parallel to toner supply from the toner container.SOLUTION: A controller, if no toner in a toner storage is detected by a toner detector even though the prescribed time for supplying toner from a toner container to the toner storage has arrived (YES at step S10) executes a first mode of driving toner discharging means for a discharging period set to a value regarding the volume of toner supplied from the toner storage to a developing device during a prescribed length of time (step S12). In the first mode, if the supply volume is a first supply volume, the discharging period is set to a first discharging period, or if the supply volume is a second supply volume greater than the first supply volume, the discharging period is set to a second discharging period longer than the first discharging period.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an image forming apparatus such as an electrophotographic system or an electrostatic recording system, and more particularly to an image forming apparatus capable of detecting the replacement timing of a toner container.

  2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus has been widely applied as a copying machine, a printer, a plotter, a facsimile, and a multifunction machine having a plurality of these functions. In these image forming apparatuses, fine powder toner is used as a part of a developer component for image formation. 2. Description of the Related Art Image forming apparatuses using toner are widely used in which a container filled with toner (hereinafter referred to as a toner container) is detachably attached to the apparatus main body.

  In this image forming apparatus, for example, a toner hopper capable of storing toner supplied from a toner container mounted on the apparatus main body and supplying the stored toner to the developing device is provided. The toner hopper is provided with a toner remaining amount detection sensor. When the control unit detects that the toner remaining amount in the toner hopper is low by the toner remaining amount detection sensor, the control unit supplies toner from the toner container to the toner hopper. When the remaining amount of toner in the toner container is low and the desired toner amount cannot be supplied to the toner hopper, the control unit displays on the display unit a prompt to replace the toner container (hereinafter referred to as replacement display), and the user Inform them that it is time to replace the toner container.

  As a technique for detecting that the remaining amount of toner in the toner container has decreased using the toner remaining amount detection sensor of the toner hopper, for example, there are the following methods. For example, an image forming apparatus that detects a toner remaining amount in a toner container by detecting whether or not a state in which the amount of toner in the toner hopper is less than a predetermined amount is longer than a predetermined time by using a toner remaining amount detection sensor of the toner hopper. It has been developed (see Patent Document 1). In this image forming apparatus, when the return time from the time when the toner in the toner hopper is less than the specified amount to the time when the toner is replenished and returned from the toner container is longer than the specified time, the control unit causes the remaining amount of toner in the toner container to be Judge that it is low. Thus, the control unit displays the replacement of the toner container on the display unit, assuming that the toner container has reached the replacement time.

  Further, for example, the toner remaining amount detection sensor of the toner hopper is used to detect the remaining amount of toner in the toner container by forcibly supplying toner from the toner hopper to the developing device without interrupting the image forming operation and consuming the toner. An image forming apparatus is known (see Patent Document 2). In this image forming apparatus, when the toner supply to the developing device is forcibly replenished, it is determined that the remaining amount of toner in the toner container is low if the temporal change in the detection value of the toner remaining amount detection sensor is small. Thus, the control unit displays the replacement of the toner container on the display unit, assuming that the toner container has reached the replacement time.

JP 2010-175792 A JP 2005-309322 A

  However, in the image forming apparatus disclosed in Patent Document 1 described above, since the return time is longer than the specified time, the control unit determines that the remaining amount of toner in the toner container is low and the toner container has reached the replacement time. doing. Here, when the toner is supplied from the toner container to the toner hopper and images with a high printing rate are continuously printed, the following problems may occur. When images with a high printing rate are continuously printed, toner consumption in the developing device increases. For this reason, since a large amount of toner is supplied from the toner hopper to the developing device at the same time as the toner is supplied from the toner container to the toner hopper, even if the remaining amount of toner in the toner container is sufficiently large The time may be longer than the specified time. As described above, since the recovery time varies depending on the amount of toner consumed in the developing device during the recovery operation, there is a possibility that an error in detecting the remaining amount of toner in the toner container may occur. For this reason, even when the remaining amount of toner in the toner container is large, there is a possibility that the toner container is erroneously detected as having a small remaining amount of toner and the replacement of the toner container is displayed. That is, in this image forming apparatus, there is a possibility that the remaining amount of toner in the toner container determined to have reached the replacement time has not been sufficiently reduced.

  In the image forming apparatus disclosed in Patent Document 2 described above, the image forming operation is interrupted and the toner is forcibly replenished. Therefore, the frequency of interrupting the image forming operation increases particularly when the toner in the toner container is reduced. There is a possibility. In particular, when the toner supply capacity from the toner container to the toner hopper is greatly reduced due to a decrease in the remaining amount of toner in the toner container, the frequency of interrupting the image forming operation becomes significant. As a result, there is a possibility that a problem that the productivity of image formation by the image forming apparatus is lowered may occur. As described above, the reduction in the remaining amount of toner in the toner container that is determined to have reached the replacement time is in conflict with the maintenance of productivity by avoiding interruption of the image forming operation. Both were desired.

  According to the present invention, even when a large amount of toner is consumed in parallel with toner replenishment from the toner container, the remaining amount of toner in the toner container that has reached the replacement time is sufficiently reduced without causing a decrease in productivity in image formation. An object of the present invention is to provide an image forming apparatus that can be reduced.

  An image forming apparatus according to the present invention includes a toner container in which toner is stored, a toner discharging unit that can discharge toner from the toner container, a toner storage unit that stores toner discharged from the toner container, and an image carrier. A toner supply unit capable of supplying toner stored in the toner storage unit to a developing device that develops the electrostatic latent image formed on the toner with toner; and whether toner is stored in the toner storage unit A toner detection unit capable of detecting the toner, and a control unit that controls to replenish the toner storage unit from the toner container by driving the toner discharge unit when no toner is detected in the toner storage unit. And the control unit causes the toner detection unit to detect the toner storage unit even when a time for supplying toner from the toner container to the toner storage unit reaches a specified time. When no toner is detected, a discharge mode for driving the toner discharge unit is executed during a discharge time set by a value related to the amount of toner supplied from the toner container to the developing device during the specified time. In the discharge mode, when the supply amount is the first supply amount, the discharge time is the first discharge time, and the supply amount is a second supply amount that is greater than the first supply amount. The discharge time is a second discharge time longer than the first discharge time.

  According to the present invention, the control unit performs the following when the toner detection unit does not detect the toner in the toner storage unit even when the toner replenishment time from the toner container to the toner storage unit reaches a specified time. . In this case, the control unit executes a discharge mode in which the toner discharge unit is driven during a discharge time set by a value related to the amount of toner supplied from the toner storage unit to the developing device during a specified time. In the discharge mode, the discharge time is set as the first discharge time when the supply amount is the first supply amount, and the discharge time is set when the supply amount is the second supply amount larger than the first supply amount. The second discharge time is longer than the first discharge time.

  Accordingly, when it is determined that the toner container replacement time has arrived when the toner detection unit does not detect the toner in the toner storage unit even when the toner supply time from the toner container to the toner storage unit reaches a specified time. In comparison, the remaining amount of toner in the toner container can be further reduced. Further, since it is not necessary to interrupt the image forming operation, it is possible to avoid a decrease in productivity of image formation by the image forming apparatus as compared with a case where the image forming operation is interrupted and toner is forcibly supplied. For this reason, even when a large amount of toner is consumed in parallel with toner replenishment from the toner container, the toner that has reached the replacement time without avoiding interruption of the image forming operation and reducing the productivity in image formation. The remaining amount of toner in the container can be sufficiently reduced.

1 is a perspective view illustrating a schematic configuration of an image forming apparatus according to an embodiment. 1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment. FIG. 3 is an explanatory diagram illustrating connection of a control unit of the image forming apparatus according to the embodiment. 7 is a flowchart illustrating a processing procedure when toner in a toner container is reduced by the image forming apparatus according to the embodiment. 4 is a graph showing each relationship in the image forming apparatus according to the embodiment, where (a) shows the relationship between the remaining amount of toner in the toner container and the discharge amount within a specified time, and (b) shows the discharge time from the toner container and the toner. This is the relationship with the remaining amount of toner in the container. 3 is a graph showing each relationship in the image forming apparatus according to the embodiment, where (a) is a relationship between the toner supply amount within a specified time and a discharge time from the toner container, (b) is a stepped graph, c) is a graph with representative values. FIG. 10 is an explanatory diagram illustrating connection of a control unit of an image forming apparatus according to a modification of the embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. In the present embodiment, a tandem type full color printer is described as an example of an image forming apparatus. However, the present invention is not limited to a tandem type image forming apparatus, but may be an image forming apparatus of another type, and is not limited to a full color, and may be a monochrome or a mono color.

  As shown in FIGS. 1 and 2, the image forming apparatus 1 includes an image forming apparatus main body (hereinafter referred to as an apparatus main body) 10 as a housing. An operation panel 11 is provided on the upper front side of the apparatus main body 10. In addition to the operation buttons, the operation panel 11 is provided with a display unit 11 a that can display the state of the image forming apparatus 1. The display unit 11a is connected to the control unit 70 (see FIG. 3). Accordingly, the display content of the display unit 11a is controlled by the control unit 70.

  As illustrated in FIG. 2, the apparatus main body 10 includes an image reading unit 20, a sheet feeding unit 30, an image forming unit 40, a sheet conveying unit 50, a sheet discharging unit 60, and a control unit 70. ing. Note that the sheet S as a recording material is formed with a toner image, and specific examples include plain paper, a resin sheet as a substitute for plain paper, cardboard, and an overhead projector sheet.

  The image reading unit 20 is provided on the upper part of the apparatus main body 10. The image reading unit 20 includes a platen glass (not shown) as a document placement table, a light source (not shown) that irradiates light on a document placed on the platen glass, and an image sensor (not shown) that converts reflected light into a digital signal. Etc.

  The sheet feeding unit 30 is disposed at the lower part of the apparatus main body 10 and includes sheet cassettes 31a and 31b for stacking and storing sheets S such as recording paper and feeding rollers 32a and 32b. The sheet S is fed to the image forming unit 40.

  The image forming unit 40 includes an image forming unit 80, a toner hopper (toner storage unit) 41, a toner container 42, a laser scanner 43, an intermediate transfer unit 44, a secondary transfer unit 45, and a fixing device 46. ing. The image forming unit 40 can form an image on the sheet S based on the image information. The image forming apparatus 1 according to the present embodiment is compatible with full color, and the image forming units 80y, 80m, 80c, and 80k are yellow (y), magenta (m), cyan (c), black ( Each of the four colors k) is provided separately with the same configuration. Similarly, the toner hoppers 41y, 41m, 41c, and 41k and the toner containers 42y, 42m, 42c, and 42k have the same configuration for each of the four colors of yellow (y), magenta (m), cyan (c), and black (k). It is provided separately. For this reason, in FIG. 2, each of the four color components is shown with the same symbol followed by a color identifier. However, in FIG. 3 and the description, there may be a case where only the symbol is used without adding the color identifier. .

  The toner containers 42y, 42m, 42c, and 42k contain toner, and are disposed above the image forming units 80y, 80m, 80c, and 80k via toner hoppers 41y, 41m, 41c, and 41k. The toner containers 42y, 42m, 42c, and 42k are, for example, cylindrical bottles having a toner discharge port at one end, have a spiral convex portion on the inner peripheral surface, and the convex portion serves as a toner discharge port by rotation. Transport. In this embodiment, a toner having an average particle diameter of about 6 μm obtained by pulverizing and classifying a kneaded pigment in a resin binder mainly composed of polyester is used. Here, as shown in FIG. 1, toner container covers 10y, 10m, 10c, and 10k are provided at the front of the apparatus main body 10 so as to be openable and closable. For example, when the toner container cover 10y is opened, the toner container 42y can be attached to and detached from the front surface of the apparatus main body 10. Similarly, when the toner container covers 10m, 10c, and 10k are opened, the toner containers 42m, 42c, and 42k can be attached to and detached from the apparatus body 10 from the front.

  As shown in FIG. 2, the image forming unit 80 includes photosensitive drums (image carriers) 81y, 81m, 81c, and 81k that form toner images, a charging roller 82, a developing device 83, and a cleaning blade 84. ing. In the present embodiment, the image forming unit 80 is detachable from the apparatus main body 10. Further, the photosensitive drum 81, the charging roller 82, the developing device 83, the cleaning blade 84, and the developing sleeve 87 described later are also yellow (y), magenta (m), cyan (c), and black (k). These four colors are separately provided with the same configuration.

  The photosensitive drum 81 is rotated by a drum motor (not shown), and carries an electrostatic image formed on the basis of image information when an image is formed, and moves around. The charging roller 82 contacts the surface of the photosensitive drum 81 and charges the surface.

  As shown in FIG. 3, the developing device 83 includes a developing container 85, a stirring screw 86, and a developing sleeve 87 (see FIG. 2) rotatably provided at the opening of the developing container 85, and a photosensitive drum. The electrostatic latent image formed on 81 is developed with toner. The developing container 85 is supplied with toner from the replenishing port 85a through the toner hopper 41 from the toner container 42 filled with toner. The developing container 85 contains a two-component developer that is a mixture of non-magnetic toner and magnetic carrier. A screw driving unit 88 having a motor, a gear train, and the like is connected to the stirring screw 86. The stirring screw 86 is rotated by driving the screw driving unit 88, and the toner is triboelectrically charged to the negative polarity by sliding with the magnetic carrier.

  As shown in FIG. 2, the developing sleeve 87 magnetically holds the developer inside the developing container 85 (see FIG. 3) by a magnet fixedly arranged inside, and transports it to the gap portion with the photosensitive drum 81. It has a function. The developing sleeve 87 is connected to a high voltage power supply (not shown) that applies a developing bias in which a DC voltage and an AC voltage are superimposed. The developing sleeve 87 executes a developing process by attaching toner to the electrostatic latent image by a developing bias.

  Further, as shown in FIG. 3, a toner concentration detection sensor 89 is provided at a part of the bottom of the developing container 85. The toner concentration detection sensor 89 can detect the amount of toner in the developing container 85 and transmits the detection result to the control unit 70.

  The toner hopper 41 includes a storage container 47 and a supply screw (toner supply means) 48 provided at a lower portion of the storage container 47 and stores the toner discharged from the toner container 42. The storage container 47 has a substantially vertically long shape, and includes a receiving port 47a that is opened at the top and into which the toner discharge port of the toner container 42 is inserted, and a supply port 47b that is opened at the bottom and faces the replenishing port 85a of the developing container 85. Have. The supply screw 48 discharges the toner stored in the storage container 47 by rotation, and supplies the toner to the developing container 85 from the supply port 85a.

  In the vicinity of the toner hopper 41, a toner container driving unit (toner discharging unit) 71 and a supply screw driving unit (toner supplying unit) 72 are provided. The toner container driving unit 71 has a motor and a gear train, and is connected to the toner container 42 inserted into the receiving port 47a. The toner container 42 can rotate the toner container 42. It can be discharged. The supply screw drive unit 72 includes a motor and a gear train, is connected to the supply screw 48, and can rotate the supply screw 48. That is, the supply screw driving unit 72 and the supply screw 48 can supply the toner stored in the toner hopper 41 to the developing device 83. Note that the toner container driving unit 71 and the supply screw driving unit 72 are both connected to the control unit 70 and controlled by the control unit 70. In addition, the toner hopper 41 can store more toner than the maximum supply amount of toner from the toner hopper 41 to the developing device 83 in a total time of a specified time and a longest discharge time described later.

  In addition, a toner remaining amount detection sensor (toner detection unit) 73 is provided on a part of the side wall of the storage container 47. The toner remaining amount detection sensor 73 is provided so as to be able to detect whether or not the toner hopper 41 contains toner of a maximum supply amount or more, which will be described later. The toner remaining amount detection sensor 73 is, for example, a piezo-type sensor, and detects the height of the toner powder surface using the fact that the output voltage changes depending on the presence or absence of toner near the sensor surface. That is, the toner remaining amount detection sensor 73 can detect whether or not the toner is stored in the toner hopper 41. The toner remaining amount detection sensor 73 is connected to the control unit 70 and transmits a detection result to the control unit 70.

  As shown in FIG. 2, the cleaning blade 84 is disposed in contact with the surface of the photosensitive drum 81 and cleans the developer remaining on the surface of the photosensitive drum 81 after the primary transfer. The cleaning blade 84 is made of, for example, urethane rubber, and is attached to and supported by a metal support plate (not shown).

  The laser scanner 43 exposes the surface of the photosensitive drum 81 charged by the charging roller 82 to form an electrostatic latent image on the surface of the photosensitive drum 81.

  The intermediate transfer unit 44 is disposed above the image forming unit 80. The intermediate transfer unit 44 includes a plurality of rollers such as a driving roller 44a, a follower roller (not shown), primary transfer rollers 44y, 44m, 44c, and 44k, and an intermediate transfer belt 44b wound around these rollers. . The primary transfer rollers 44y, 44m, 44c, and 44k are disposed to face the photosensitive drums 81y, 81m, 81c, and 81k, respectively, and contact the intermediate transfer belt 44b.

  The intermediate transfer belt 44b is under a certain tension even when not being driven, and is not in contact with the photosensitive drums 81y, 81m, 81c, 81k, but is always in contact therewith. By applying a positive transfer bias to the intermediate transfer belt 44b by the primary transfer rollers 44y, 44m, 44c, and 44k, toner images having respective negative polarities on the photosensitive drums 81y, 81m, 81c, and 81k are sequentially transferred to the intermediate transfer belt 44b. Multiple transfer is performed on the belt 44b. Accordingly, the intermediate transfer belt 44b moves by transferring a full-color toner image obtained by developing the electrostatic image on the surface of the photosensitive drums 81y, 81m, 81c, and 81k.

  The secondary transfer unit 45 includes a secondary transfer inner roller 45a and a secondary transfer outer roller 45b. A full color image formed on the intermediate transfer belt 44b is transferred to the sheet S by applying a positive secondary transfer bias to the secondary transfer outer roller 45b. The secondary transfer inner roller 45a stretches the intermediate transfer belt 44b inside the intermediate transfer belt 44b, and the secondary transfer outer roller 45b faces the secondary transfer inner roller 45a across the intermediate transfer belt 44b. It is provided in the position to do.

  The fixing device 46 includes a fixing roller 46a and a pressure roller 46b. When the sheet S is nipped and conveyed between the fixing roller 46 a and the pressure roller 46 b, the toner image transferred to the sheet S is heated and pressurized and fixed to the sheet S. The fixing device 46 constitutes one unit and can be inserted into and removed from the apparatus main body 10.

  The sheet conveying unit 50 includes a pre-secondary transfer conveying path 51, a pre-fixing conveying path 52, a discharge path 53, and a re-conveying path 54, and forms an image of the sheet S fed from the sheet feeding unit 30. The sheet is conveyed from the section 40 to the sheet discharge section 60.

  The sheet discharge unit 60 includes a discharge roller pair 61 disposed on the downstream side of the discharge path 53 and a discharge tray 62 disposed on the downstream side of the discharge roller pair 61. The discharge roller pair 61 feeds the sheet S conveyed from the discharge path 53 from the nip portion and discharges the sheet S to the discharge tray 62 through the discharge port 10 a formed in the apparatus main body 10. The discharge tray 62 is a face-down tray, and stacks the sheets S discharged in the arrow X direction from the discharge port 10a.

  The control unit 70 is configured by a computer and includes, for example, a CPU, a ROM that stores a program for controlling each unit, a RAM that temporarily stores data, and an input / output circuit that inputs and outputs signals to and from the outside. The control unit 70 is connected to the image reading unit 20, the sheet feeding unit 30, the image forming unit 40, the sheet conveying unit 50, and the sheet discharging unit 60 through an input / output circuit, and exchanges signals with each unit and operates. Control. Further, the control unit 70 can be operated and set by the user by a command from a computer (not shown) connected to the apparatus main body 10, an operation of the operation panel 11, and the like.

  When no toner is detected in the toner hopper 41, the control unit 70 drives the toner container driving unit 71 while maintaining the driving state of the supply screw driving unit 72 and the supply screw 48 to supply toner from the toner container 42 to the toner hopper 41. Control to replenish. That is, the control unit 70 performs control so that toner is supplied from the toner container 42 to the toner hopper 41 without interrupting the image forming operation. In addition, when the toner remaining amount detection sensor 73 does not detect the toner in the toner hopper 41 even when the toner replenishment time from the toner container 42 to the toner hopper 41 reaches a specified time, the control unit 70 executes the following control. To do. In this case, the control unit 70 drives the toner container driving unit 71 in the first mode (discharge) during the discharge time set by the value related to the amount of toner supplied from the toner hopper 41 to the developing device 83 during the specified time. Mode). Here, in this first mode, for example, when the toner supply amount is 5% (first supply amount), the control unit 70 sets the discharge time to 120 seconds (first discharge time). (See FIG. 6). In this first mode, for example, when the toner supply amount is 100% (second supply amount) larger than 5%, the control unit 70 sets the discharge time to 500 seconds (first time) longer than 120 seconds. 2 discharge time) (see FIG. 6). The control unit 70 displays on the display unit 11a that it is time to replace the toner container 42 after the end of the first mode.

  In addition, the control unit 70 calculates the amount of toner supplied from the toner hopper 41 to the developing device 83 based on the drive time of the supply screw drive unit 72 at a specified time. Further, when the toner remaining amount detection sensor 73 detects the toner in the toner hopper 41 when the first mode is executed, the control unit 70 stops the driving of the toner container driving unit 71 in the second mode (stopping). Mode).

  Next, an image forming operation in the image forming apparatus 1 configured as described above will be described.

  As shown in FIG. 2, when the image forming operation is started, first, the photosensitive drum 81 is rotated and the surface is charged by the charging roller 82. Then, laser light is emitted from the laser scanner 43 to the photosensitive drum 81 based on the image information, and an electrostatic latent image is formed on the surface of the photosensitive drum 81. When toner adheres to the electrostatic latent image, it is developed and visualized as a toner image, and transferred to the intermediate transfer belt 44b.

  On the other hand, the feeding rollers 32a and 32b are rotated in parallel with the toner image forming operation, and the uppermost sheet S of the sheet cassettes 31a and 31b is fed while being separated. Then, the sheet S is conveyed to the secondary transfer unit 45 via the pre-secondary transfer conveyance path 51 in synchronization with the toner image on the intermediate transfer belt 44b. Further, the image is transferred from the intermediate transfer belt 44b to the sheet S, and the sheet S is conveyed to the fixing device 46, where an unfixed toner image is heated and pressed to be fixed on the surface of the sheet S, and a pair of discharge rollers. 61 is discharged from the discharge port 10a and stacked on the discharge tray 62.

  Next, a processing procedure when the remaining amount of toner in the toner container 42 is reduced by the image forming apparatus 1 described above will be described in detail with reference to the flowchart of FIG. 4 and the graphs of FIGS.

  When the image forming apparatus 1 is powered on, the control unit 70 detects the toner amount in the developing container 85 of the developing device 83 by the toner density detection sensor 89 at an appropriate timing, and the toner amount in the developing device 83 is determined. It is determined whether it is less than a predetermined threshold (step S1). If the control unit 70 determines that the toner amount of the developing device 83 is not less than the predetermined threshold value, the process ends.

  When the controller 70 determines that the amount of toner in the developing device 83 is less than a predetermined threshold, the controller 70 drives the supply screw driving unit 72 to rotate the supply screw 48 and replenishes the developing device 83 with toner from the toner hopper 41 ( Step S2). When toner supply to the developing device 83 is repeated by driving the supply screw driving unit 72, the amount of toner stored in the toner hopper 41 decreases.

  The control unit 70 determines whether the toner remaining in the toner hopper 41 can be detected by the toner remaining amount detection sensor 73 (step S3). When the control unit 70 determines that the toner in the toner hopper 41 can be detected, the process ends. When the control unit 70 determines that the toner in the toner hopper 41 cannot be detected, the control unit 70 starts counting a timer to measure the specified time (step S4). Then, the control unit 70 drives the toner container driving unit 71 to rotate the toner container 42 assuming that the toner hopper 41 is short of toner. As a result, the control unit 70 performs a return operation for supplying toner from the toner container 42 to the toner hopper 41 (step S5). Here, the control unit 70 can execute the replenishment operation (step S5) from the toner container 42 to the toner hopper 41 in parallel with the image process and the replenishment operation (step S2) to the developing device 83, and to the developing device 83. It can be executed independently even when the replenishment operation is not performed.

  In parallel with the return operation, the control unit 70 starts counting the toner supply amount (= toner consumption amount) from the toner hopper 41 to the developing device 83. Specifically, the cumulative replenishment time from the toner hopper 41 to the developing device 83 is obtained by integrating the driving time of the supply screw driving unit 72 of the toner hopper 41 by the control unit 70 (step S6). The controller 70 estimates the remaining amount of toner in the toner container 42 based on the value related to the toner supply amount during the return operation (step S5).

  The controller 70 determines whether or not the toner remaining in the toner hopper 41 can be detected by the toner remaining amount detection sensor 73 (step S7). When determining that the toner in the toner hopper 41 can be detected, the control unit 70 stops driving the toner container driving unit 71 (step S8), and resets the accumulated driving time of the supply screw driving unit 72 (step S9). . When it is determined that the toner in the toner hopper 41 cannot be detected, the control unit 70 determines whether or not the timer has reached a specified time (step S10). When it is determined that the timer has not reached the specified time, the control unit 70 continues the return operation (step S5) and the integration of the drive time of the supply screw drive unit 72 (step S6).

  If the controller 70 determines that the timer has reached the specified time, the supply of toner does not catch up with the toner consumption, assuming that the toner remaining amount detection sensor 73 does not detect the toner in the toner hopper 41 during the specified time. Judge that it is impossible to follow. Here, in order to increase the amount of toner stored in the toner hopper 41 and return to a state where full toner is detected again after the toner remaining amount detection sensor 73 detects the toner shortage, the toner container 42 is used for image formation. A toner discharge amount greater than the toner consumption amount is required. On the other hand, as shown in FIG. 5A, the discharge amount from the toner container 42 which is a cylindrical bottle varies depending on the remaining toner amount inside, and the discharge amount with respect to the rotational drive time decreases as the remaining toner amount decreases. Decreases with it. For this reason, since the remaining amount of toner in the toner container 42 is reduced, a desired discharge amount cannot be obtained even by the replenishment operation from the toner container 42 to the toner hopper 41.

  On the other hand, when an image with a high printing rate is output continuously, the amount of toner consumed per unit time is large (consumption speed is faster) than when an image with a low printing rate is output or output intermittently. As described above, in order to maintain the toner amount stored in the toner hopper 41, the toner container 42 is required to have a toner discharge amount that is equal to or greater than the toner consumption amount. Needs to remain in the toner container 42. Therefore, even if the toner container 42 can follow the output of the low print image, the toner container 42 cannot follow the output of the high print image.

  Suppose that it is determined in step S10 that the toner in the toner container 42 has run out when the timer reaches a specified time. In this case, for example, in the toner container 42 having the toner discharge characteristic shown in FIG. 5A, if it is determined that there is no toner at a printing rate of 5%, the remaining amount of the toner container 42 is 40 (g). On the other hand, if it is determined that the toner container 42 has the maximum toner consumption speed and no toner in the same toner container 42, the remaining amount of the toner container 42 is 150 (g).

  Therefore, in the image forming apparatus 1 of the present embodiment, when the timer reaches the specified time in step S10 and it is determined that the supply from the toner container 42 cannot follow the toner consumption, the remaining toner in the toner container 42 is discharged. Move to discharge operation. However, since this discharging operation is unnecessary when the remaining amount of toner in the toner container 42 is sufficiently small, the remaining amount of toner in the toner container 42 is estimated and the discharging operation is performed so as not to be too long. . In this way, by shortening the length of the discharge time as much as possible, the processing time when the remaining amount of toner in the toner container 42 is reduced can be minimized, and a decrease in productivity can be avoided.

  Here, the image forming operation is continued even during the operation of discharging the remaining toner in the toner container 42. For this reason, when the amount of toner in the toner hopper 41 decreases during the operation of discharging the remaining toner in the toner container 42, the image forming process needs to be stopped because the toner is insufficient and the image cannot be formed. There is. Therefore, simply setting the execution time of the remaining toner discharge operation of the toner container 42 as a result may interrupt the image forming process and cause a decrease in productivity as in the prior art. is there. On the other hand, in this embodiment, the discharge time from the toner container 42 is calculated and appropriately set to avoid a decrease in productivity. It should be noted that the detection of the situation where the toner in the toner hopper 41 is reduced is executed by the following processing method, for example. For example, when the controller 70 detects that there is no toner in the toner hopper 41 for a specified time by the toner remaining amount detection sensor 73 and then counts the toner supply amount from the toner hopper 41 to the developing device 83 by a predetermined amount, Detected. Alternatively, the toner hopper 41 may be provided with a toner end sensor in addition to the toner remaining amount detection sensor 73 to detect the actual toner amount in the toner hopper 41.

  The control unit 70 calculates the discharge time from the toner container 42 based on the integrated value of the drive time of the supply screw drive unit 72 (step S11). A specific method will be described below. A specified time is provided for the operation of driving the toner container 42 and supplying the toner to the toner hopper 41. If the maximum toner consumption during the specified time is V (g), the remaining toner amount T (g) in the toner container 42 necessary for supplying the toner of V (g) can be obtained in advance by experiments. (See FIG. 5 (a)). Further, when the toner remaining amount at the time of replacing the toner container 42 is set to Tmin (g) or less, the driving time t of the toner container 42 necessary for discharging from the state of the toner remaining amount T (g) to Tmin (g). (Seconds) can be obtained by experiment separately. The discharging operation does not have to be the same as that in step S5. For example, the rotation speed of the toner container 42 may be increased, or the on / off ratio of the intermittent operation may be changed.

  FIG. 5B shows the transition of the remaining amount of toner with respect to the discharge operation time of a certain toner container 42. For example, when T = 150 (g) and Tmin = 30 (g), it can be seen that t = 500 (seconds) is required for the discharge operation. Similarly, in the case where the toner consumption amount within the specified time is half of the maximum toner consumption amount V (g), or in the case where the consumption amount is small such as continuous output of an image with a printing rate of 5%, FIGS. The discharge time can be calculated from (b). Examples of the case where the toner consumption amount within the specified time is half of the maximum toner consumption amount V (g) include, for example, continuous output of an image with a printing rate of 50%, intermittent output of a high print image with 50% or more, In the middle, the stop of image formation can be mentioned. For example, if the toner consumption is 0.5 V (g), T1 = 120 (g), t1 = 450 (seconds), and if the toner consumption is 0.05 V (g), T2 = 40. (G), and t2 = 120 (seconds). Even when image formation is stopped, that is, when the toner container 42 cannot be discharged to Tmin (g) even when toner is not consumed, the discharge operation is different from step S5 and the minimum discharge operation amount t0 (seconds) can be set (for example, , T0 = 40 (seconds)).

  FIG. 6A shows the relationship between the discharge operation amount and the toner consumption amount within the specified time obtained as described above. In step S11, the control unit 70 sets the discharge time using the relationship shown in FIG. In mounting, this relationship may be held in the storage unit as a lookup table and sequentially referred to. In this case, the discharge time for an arbitrary toner consumption is obtained by approximating a staircase as shown in FIG. 6B or by interpolating between representative values (white circles) as shown in FIG. 6C. Also good. Here, the look-up table is provided so that the driving amount of the toner container 42 increases as the calculation result of the toner consumption increases, and the remaining amount after the toner discharging operation of the toner container 42 is completed is almost constant. It is preferable to determine so that.

  The controller 70 drives the toner container driving unit 71 to rotate the toner container 42 during the calculated discharging time, and discharges the toner from the toner container 42 to the toner hopper 41 (step S12, first mode). Here, the toner hopper 41 can store toner that exceeds the maximum amount of toner supplied from the toner hopper 41 to the developing device 83 in the total time of the specified time and the discharge time. Therefore, the toner in the toner hopper 41 is not depleted before the toner discharging operation is completed, and a problem that a desired image density cannot be obtained due to the failure to maintain the supply to the developing device 83 is prevented. be able to.

  The controller 70 determines whether or not the toner remaining in the toner hopper 41 can be detected by the toner remaining amount detection sensor 73 (step S13). When the control unit 70 determines that the toner in the toner hopper 41 can be detected, the control unit 70 stops driving the toner container driving unit 71 (step S14, second mode). When determining that the toner in the toner hopper 41 cannot be detected, the control unit 70 determines whether or not the discharging operation is completed (step S15). The determination as to whether or not the discharging operation has been completed here is based on whether or not the discharging time has elapsed.

  If the controller 70 determines that the discharging operation has not been completed, the controller 70 continues discharging toner from the toner container 42 to the toner hopper 41 (step S12). If the controller 70 determines that the discharge operation has been completed, it assumes that the toner in the toner container 42 has run out, and displays the replacement of the toner container 42 on the display unit 11a (step S16).

  As described above, according to the image forming apparatus 1 of the present embodiment, the toner remaining in the toner hopper 41 is not detected by the toner remaining amount detection sensor 73 even when the toner replenishment time from the toner container 42 to the toner hopper 41 reaches a specified time. In the case: In this case, the remaining amount of toner in the toner container 42 can be further reduced as compared with the case where it is determined that the toner container 42 replacement time has been reached. Further, since it is not necessary to interrupt the image forming operation, it is possible to avoid a decrease in productivity of image formation by the image forming apparatus 1 as compared with a case where the image forming operation is interrupted and toner is forcibly supplied. . For this reason, even when a large amount of toner is consumed in parallel with toner replenishment from the toner container 42, the replacement time has been reached without interrupting the image forming operation and causing a decrease in productivity in image formation. The remaining amount of toner in the toner container 42 can be sufficiently reduced.

  Further, according to the image forming apparatus 1 of the present embodiment, the toner hopper 41 can store toner that exceeds the maximum supply amount of toner from the toner hopper 41 to the developing device 83 in the total time of the specified time and the discharge time. . Therefore, the toner in the toner hopper 41 is not depleted before the toner discharging operation is completed, and a problem that a desired image density cannot be obtained due to the failure to maintain the supply to the developing device 83 is prevented. be able to. Accordingly, it is not necessary to interrupt the image formation until the toner container 42 determines that no toner is supplied even after the supply by the toner container 42 cannot follow the consumption, and the productivity of the image forming apparatus 1 can be maintained. .

  In the image forming apparatus 1 according to the present embodiment described above, the control unit 70 calculates the amount of toner supplied from the toner hopper 41 to the developing device 83 based on the drive time of the supply screw drive unit 72 at a specified time. Although described, it is not limited to this. For example, the control unit 70 may calculate the amount of toner supplied from the toner hopper 41 to the developing device 83 based on a value related to the amount of toner consumed by the developing device 83 during a specified time. In this case, the value related to the amount of toner consumed by the developing device 83 is based on the integrated value (for example, the printing rate or video count value) of the image data of the electrostatic latent image developed by the developing device 83 in the specified time. Can be calculated. Further, when the relationship between the replenishment amount and the replenishment time is not stable, such as when the toner supply amount per unit time by the toner hopper 41 is large, it is preferable to obtain and integrate the toner consumption based on the image signal.

  Further, in the image forming apparatus 1 of the present embodiment, the case where the separate drive units 71 and 72 for driving the toner container 42 and the supply screw 48 are described has been described, but the present invention is not limited thereto. For example, as shown in FIG. 7, a common drive unit 74 that drives the toner container 42 and the supply screw 48 may be provided. In this case, a first clutch 75 that is an electromagnetic clutch that can connect and disconnect the common drive unit 74 and the toner container 42, and a second clutch 76 that is an electromagnetic clutch that can connect and disconnect the common drive unit 74 and the supply screw 48. Be prepared. Thereby, since the toner container 42 and the supply screw 48 can be driven by only one common drive unit 74, the number of parts can be reduced. Also in this case, the control unit 70 can execute the replenishment operation (step S5) from the toner container 42 to the toner hopper 41 in parallel with the image process and the replenishment operation (step S2) to the developing device 83 or independently.

  Further, in the image forming apparatus 1 according to the present embodiment, when the control unit 70 determines that the discharging operation has been completed, it is assumed that the toner in the toner container 42 has run out, and the replacement display of the toner container 42 is displayed on the display unit 11a. However, the present invention is not limited to this. For example, information indicating that the toner in the toner container 42 has run out may be transmitted to another computer connected to the image forming apparatus 1 or the operation of the image forming apparatus 1 may be stopped.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 11a ... Display part, 41, 41y, 41m, 41c, 41k ... Toner hopper (toner accommodating part), 42, 42y, 42m, 42c, 42k ... Toner container, 48 ... Supply screw (toner supply means) , 70 ... control unit, 71 ... toner container driving unit (toner discharging unit), 72 ... supply screw driving unit (toner supply unit), 73 ... toner remaining amount detection sensor (toner detection unit), 81, 81y, 81m, 81c , 81k ... photosensitive drum (image carrier), 83 ... developing device.

Claims (7)

A toner container containing toner;
Toner discharging means capable of discharging toner from the toner container;
A toner containing portion for containing toner discharged from the toner container;
A toner supply unit capable of supplying the toner stored in the toner storage unit to a developing device that develops the electrostatic latent image formed on the image carrier with toner;
A toner detection unit capable of detecting whether toner is stored in the toner storage unit;
A control unit that drives the toner discharge unit to control replenishment of toner from the toner container to the toner storage unit when no toner is detected in the toner storage unit;
When the toner detection unit detects no toner in the toner storage unit even when the toner replenishment time from the toner container reaches the toner storage unit reaches a specified time, Executing a discharge mode for driving the toner discharge means during a discharge time set by a value relating to the amount of toner supplied from the toner container to the developing device;
In the discharge mode, when the supply amount is a first supply amount, the discharge time is set as a first discharge time, and when the supply amount is a second supply amount larger than the first supply amount. The discharge time is a second discharge time longer than the first discharge time,
An image forming apparatus. The toner storage unit can store toner that is equal to or more than a maximum supply amount of toner from the toner storage unit to the developing device in a total time of the specified time and the longest discharge time,
The toner detection unit can detect whether or not the toner storage unit stores toner of the maximum supply amount or more.
The image forming apparatus according to claim 1. The control unit calculates the supply amount of toner from the toner storage unit to the developing device based on a driving time of the toner supply unit at the specified time.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The control unit calculates the supply amount of toner from the toner storage unit to the developing device based on a value related to the amount of toner consumed by the developing device during the specified time.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The control unit calculates a value related to the consumption amount of toner consumed by the developing device based on an integrated value of image data of the electrostatic latent image developed by the developing device at the specified time.
The image forming apparatus according to claim 4. The control unit executes a stop mode in which the driving of the toner discharge unit is stopped when toner in the toner storage unit is detected by the toner detection unit during execution of the discharge mode.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. A display unit whose display content is controlled by the control unit;
The control unit displays on the display unit that it is time to replace the toner container after the discharge mode ends.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.

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