JP2024072332A - Image forming device and control method of the same - Google Patents

Abstract

To prevent deterioration in quality of a print image after a developer storage part is replaced.SOLUTION: An image forming device (100) includes: a developer storage part (40) for storing a developer (D); a supply member (90) for executing supply operation of the developer (D) from a developer storage part (20) to the developer storage part (40); agitation members (44, 45) for executing agitation operation of the developer (D) in the developer storage part (40); a supply member driving part (121); an agitation member driving part (122); a detection part (133) for detecting the fact that the developer storage part (20) is replaced; and a control part (110) for controlling the supply member driving part (121) and the agitation member driving part (122) in such a manner that an agitation supply period (S3) in which the agitation operation and the supply operation are simultaneously executed is provided intermittently and an agitation period (S4) in which the agitation operation is executed but the supply operation is not executed during the agitation supply period (S3) is provided after it is detected that the developer storage part (20) is replaced.SELECTED DRAWING: Figure 11

Description

This disclosure relates to an image forming apparatus and a control method thereof.

In an image forming apparatus using an electrophotographic method, the surface of a photosensitive drum is uniformly charged by a charging device, an electrostatic latent image is formed on the surface of the photosensitive drum by an exposure device, a developer image (toner image) is formed on the surface of the photosensitive drum by a developing device, and the toner image is transferred onto a recording medium by a transfer device. The developing device has a developer container (toner container) that contains developer (toner), and a developer storage section (toner cartridge) is attached to the top of the toner container. The developing device also has a rotating shutter member, which is a supply member for supplying toner into the toner container through the supply port of the toner cartridge. When the amount of toner in the toner container falls below a specified low level, or immediately after replacing the toner cartridge, the image forming apparatus rotates the rotating shutter member to perform a toner supply operation until the amount of toner in the toner container reaches a specified level (for example, toner full).

JP 2014-115380 A

However, in the above conventional device, when toner is replenished into the toner storage unit immediately after replacing the toner cartridge, the difference in characteristics between the toner remaining in the toner storage unit (i.e., degraded toner with reduced fluidity) and the replenished toner (i.e., new toner with high fluidity) makes it difficult for the degraded toner and new toner to mix uniformly, resulting in uneven density (e.g., vertical bands) on the printed image.

The present disclosure aims to prevent degradation of print image quality after replacing the developer storage unit.

The image forming apparatus disclosed herein is characterized by having a developer container that contains developer to be supplied to an image carrier, a supply member that performs a supply operation of new developer from a developer storage unit attached to the developer container to the developer container, a stirring member that performs a stirring operation of the developer in the developer container, a supply member drive unit that causes the supply member to perform the supply operation, a stirring member drive unit that causes the stirring member to perform the stirring operation, a detection unit that detects that the developer storage unit has been replaced, and a control unit that performs intermittent operation control to control the supply member drive unit and the stirring member drive unit so that, after it is detected that the developer storage unit has been replaced, a stirring supply period in which the stirring operation and the supply operation are performed simultaneously is intermittently provided, and a stirring period in which the stirring operation is performed and the supply operation is not performed is provided during the stirring supply period.

The control method of the image forming apparatus disclosed herein is a method executed by an image forming apparatus having a developer container that contains developer to be supplied to an image carrier, a supply member that performs a supply operation of new developer from a developer storage unit attached to the developer container into the developer container, a stirring member that performs a stirring operation of the developer in the developer container, a supply member drive unit that causes the supply member to perform the supply operation, a stirring member drive unit that causes the stirring member to perform the stirring operation, and a detection unit that detects that the developer storage unit has been replaced, characterized in that after it is detected that the developer storage unit has been replaced, a stirring supply period in which the stirring operation and the supply operation are performed simultaneously is intermittently provided, and a stirring period in which the stirring operation is performed and the supply operation is not performed is provided during the stirring supply period.

This disclosure makes it possible to prevent degradation of the quality of printed images after replacing the developer storage unit.

1 is a schematic cross-sectional view illustrating a configuration of an image forming apparatus according to an embodiment. FIG. 2 is a schematic cross-sectional view showing a configuration of an image forming unit shown in FIG. 1 . 2 is a block diagram illustrating a schematic configuration of a control system of the image forming apparatus according to the embodiment. FIG. 13A and 13B are diagrams illustrating an operation for detecting the amount of toner in a toner storage unit. 6 is a time chart for explaining an operation of detecting the amount of toner in the toner storage unit. 6 is a time chart for explaining a toner supply operation under normal circumstances. 13 is a table showing the results of an evaluation of the effect of toner replenishment and toner stirring performed immediately after replacing a toner cartridge on the occurrence of vertical bands in a printed image; FIG. 13 is a time chart for explaining the operation immediately after replacement of the toner cartridge of Comparative Example C1. 13 is a time chart for explaining the operation immediately after replacement of the toner cartridge of Comparative Example C2. 13 is a time chart for explaining the operation immediately after replacement of the toner cartridge of Comparative Example C3. 13 is a time chart for explaining the operation immediately after replacement of the toner cartridge in Example E1. 13 is a time chart for explaining the operation immediately after replacement of the toner cartridge in Example E2.

The image forming apparatus and the control method thereof according to the embodiment will be described below with reference to the drawings. The following embodiment is merely an example, and various modifications are possible within the scope of this disclosure.

Configuration of Image Forming Apparatus
1 is a schematic cross-sectional view showing the configuration of an image forming apparatus 100 according to an embodiment. The image forming apparatus 100 is an apparatus that forms an image using toner as a developer, and more specifically, is a printing apparatus that forms an image on a recording medium by an electrophotographic method. The image forming apparatus 100 is, for example, a printer capable of color printing.

Image forming device 100 has image forming units 1K, 1Y, 1M, and 1C (also referred to as "image forming units 1") that form images of black (K), yellow (Y), magenta (M), and cyan (C), respectively. Image forming units 1K, 1Y, 1M, and 1C each have process units 10K, 10Y, 10M, and 10C (also referred to as "process unit 10") and toner cartridges 20K, 20Y, 20M, and 20C (also referred to as "toner cartridge 20") as developer storage units.

The process units 10K, 10Y, 10M, and 10C form toner images using toners of K, Y, M, and C colors, respectively. Each of the process units 10K, 10Y, 10M, and 10C includes a photosensitive drum 11 as an image carrier and a developing device 14 that develops the electrostatic latent image on the photosensitive drum 11 with toner. Above the photosensitive drum 11 of each process unit, an LED (Light Emitting Diode) head 2, which is an exposure device as an electrostatic latent image forming means, is installed with a certain gap therebetween, and the electrostatic latent image on each photosensitive drum 11 is formed by the corresponding LED head 2. Each process unit 10 is, for example, detachably attached to the main body of the image forming apparatus 100. Each developing device 14 includes a toner container (40 in FIG. 2 described later) as a developer container, and a toner cartridge attached to the toner container.

Toner cartridges 20K, 20Y, 20M, and 20C store new toner of the colors K, Y, M, and C, respectively. Toner cartridges 20K, 20Y, 20M, and 20C are disposed above the toner storage section of the developing device 14 of process units 10K, 10Y, 10M, and 10C, respectively, and the new toner stored in each toner cartridge is replenished into the toner storage section of the developing device 14 of the corresponding process unit. Each toner cartridge is, for example, removably attached to the corresponding process unit.

The image forming device 100 has a tray 3 that stores recording media P such as paper, a paper feed roller 4 that picks up the recording media P from the tray 3 one by one, and a transport roller 5 that transports the recording media P picked up by the paper feed roller 4 toward the image forming units 1K, 1Y, 1M, and 1C. The recording media P is transported along a transport path W.

Downstream of the transport roller 5 in the transport direction of the recording medium P, along the transport path W, are image forming units 1K, 1Y, 1M, and 1C, a transfer device 6, a fixing device 7, discharge rollers 8a and 8b, and a stacker cover 9, which is the discharge section.

The transfer device 6 is disposed opposite the image forming units 1K, 1Y, 1M, and 1C across the transport path W, and transfers the toner images formed by each image forming unit onto the recording medium P. The transfer device 6 has an endless transfer belt 6a that transports the recording medium P from the transport roller 5 along the image forming units 1K, 1Y, 1M, and 1C, a drive roller 6b and a driven roller 6c that are tension rollers that tension and drive the transfer belt 6a, and four transfer rollers 6d that are transfer means that transfer the toner images formed on the photosensitive drums 11 of each image forming unit onto the recording medium P on the transfer belt 6a.

The fixing device 7 is disposed downstream of the transfer device 6 in the medium transport direction, and fixes the toner image transferred onto the recording medium P by the transfer device 6. The fixing device 7 includes a heating roller 7a and a pressure roller 7b, and applies heat and pressure to the toner between these rollers to fix the toner to the recording medium P.

The discharge rollers 8a and 8b discharge the recording medium P, on which the toner image has been fixed by the fixing unit 7, to the outside of the device. The stacker cover 9 holds the recording medium P discharged by the discharge rollers 8a and 8b.

Configuration of Image Forming Unit
Fig. 2 is a schematic cross-sectional view showing the configuration of the image forming unit 1K shown in Fig. 1. The configuration of the image forming unit 1K will be described below with reference to Fig. 2. Note that the configurations of the image forming units 1Y, 1M, and 1C are the same as the configuration of the image forming unit 1K.

The process unit 10K has a case 19 and a photosensitive drum 11 arranged inside the case 19. The photosensitive drum 11 is a member that carries an electrostatic latent image and rotates in the direction R11. A charging roller 12 as a charging device, a developing roller 41 as a developer carrier, and a cleaning device 15 are arranged in this order along the rotation direction of the photosensitive drum 11. An LED head 2 is arranged between the charging roller 12 and the developing roller 41, facing the photosensitive drum 11. In addition, a transfer roller 6d is arranged between the developing roller 41 and the cleaning device 15, facing the photosensitive drum 11.

The charging roller 12 uniformly charges the surface of the photosensitive drum 11, and here is a charging roller arranged in contact with the photosensitive drum 11. The LED head 2 may be an exposure device using a light source such as a laser. The developing roller 41 develops the electrostatic latent image formed on the photosensitive drum 11 with toner D to form a toner image. The transfer roller 6d transfers the toner image formed on the photosensitive drum 11 onto the recording medium P. The cleaning device 15 removes the toner D remaining on the surface of the photosensitive drum 11 without being transferred to the recording medium P. The cleaning device 15 has a cleaning blade 15a that contacts the photosensitive drum 11 to scrape off the toner D, and a waste toner conveying member 15b for discharging the toner D scraped off by the cleaning blade 15a.

The developing device 14 has a toner storage section 40 as a developer storage section, a developing roller 41 as a developer carrier, a supply roller 42 as a developer supply member, a regulating blade 43 as a developer regulating member, stirring members 44 and 45, and a toner amount detection member 46. Each of the members 41 to 46 is a member that is long in the longitudinal direction, and is arranged so that the longitudinal directions of each face in the same direction (perpendicular to the paper surface of FIG. 2).

The toner storage section 40 has a toner storage chamber 40a that stores toner D, an opening 40b that opens sideways from the bottom of the toner storage chamber 40a and faces the photosensitive drum 11, and an opening 40c that opens upward from the toner storage chamber 40a. Here, the toner storage section 40 is configured as part of the case 19 of the process unit 10K.

The developing roller 41 is a member that carries toner D, supplies toner D to the electrostatic latent image on the photosensitive drum 11, and develops the electrostatic latent image with toner D. Specifically, the developing roller 41 is disposed in contact with the photosensitive drum 11 at the lower opening 40b of the toner storage chamber 40a, and rotates in the direction R41.

The supply roller 42 is a member that supplies toner D to the developing roller 41. Specifically, the supply roller 42 is disposed in contact with the developing roller 41 at the bottom of the toner storage chamber 40a and rotates in the direction R42.

The regulating blade 43 is a member that regulates the amount of toner D on the developing roller 41, and forms a thin layer of toner D supplied from the supply roller 42 to the developing roller 41. The regulating blade 43 is disposed in contact with the developing roller 41 downstream of the supply roller 42 and upstream of the photosensitive drum 11 in the rotation direction R41 of the developing roller 41.

The stirring members 44 and 45 are members that stir the toner D in the toner storage unit 40. The stirring members 44 and 45 are crank-shaped members that are rotatably supported in the toner storage unit 40. The stirring members 44 and 45 are disposed above the supply roller 42 and below the toner amount detection member 46, and rotate in the R44 direction and the R45 direction, respectively. However, the number of stirring members is not limited to two, and may be one, or three or more.

The toner amount detection member 46 is a member for detecting the amount of toner D (i.e., the remaining amount of toner) in the toner storage unit 40. The toner amount detection member 46 has a shaft portion that is rotatably supported by the toner storage unit 40, and a flat plate portion that protrudes in one radial direction from the shaft portion.

A cover 60 is disposed on the top of the toner storage unit 40 to cover the opening 40c at the top of the toner storage unit 40. A recess 61 is formed on the top of the cover 60 to receive and support the toner cartridge 20K. The cover 60 may be a component that constitutes the process unit 10K.

In FIG. 2, the developing roller 41 and the supply roller 42 are shown as being circular, but in reality, the two rollers elastically deform when they come into contact with each other. Also, the regulating blade 43 and the cleaning blade 15a are shown as being linear, but in reality, they elastically deform when they come into contact with the developing roller 41 and the photosensitive drum 11, respectively.

The configuration of the toner supply mechanism 30 will be described below with reference to FIG. 2. The toner supply mechanism 30 includes a toner cartridge 20K, a cover 60, and a rotating shutter member 90 as a supply member, as described below.

Toner cartridge 20K is placed on cover 60. Toner cartridge 20K has toner cartridge 70 as a developer container, and agitator blade 80 that agitates toner D in toner cartridge 70. Toner cartridge 70 has a toner storage chamber that stores toner D, and discharge port 72 that is a supply port for discharging toner D in the toner storage chamber to the outside of toner cartridge 70. Discharge port 72 is specifically provided at the bottom of toner cartridge 70, and is an opening that opens downward into the toner storage chamber. The agitator blade 80 is rotatably arranged in the toner storage chamber.

In this example, the toner cartridge 70 is composed of a case 73, which is an outer member, and a supply port shutter 74, which is an inner member disposed inside the case 73. The case 73 has an opening at the bottom. The case 73 extends in a longitudinal direction (a direction perpendicular to the paper surface of FIG. 2) parallel to the longitudinal direction of the developing roller 41, and the opening is provided in the center of the case 73 in the longitudinal direction.

A toner supply port is formed in the cover 60 below the discharge port 72 of the toner cartridge 20K, which is an opening that connects the discharge port 72 to the inside of the toner storage section 40 of the developing device 14. The toner supply port is provided in the center of the cover 60 in the longitudinal direction so as to face the discharge port 72.

The process unit 10K is provided with a rotating shutter member 90, which is a transport member that transports the toner D discharged from the discharge port 72 into the toner storage section 40. The rotating shutter member 90 is rotatably arranged below the discharge port 72. In the example of FIG. 2, the rotating shutter member 90 is rotatably arranged around a rotation axis, and rotates in the same rotation direction R90 as the stirring blade 80.

The rotating shutter member 90 has multiple concave developer chambers, or toner chambers, arranged circumferentially on its outer periphery (specifically, the outer periphery of the rotating shaft). When positioned at the top, each toner chamber 91 receives toner D from the discharge port 72, and transports the toner D downward as the rotating shutter member 90 rotates, into the toner storage section 40 of the developing device 14. The toner is transported continuously as the rotating shutter member 90 rotates.

In addition, when toner is not being supplied from the toner cartridge 20K to the toner storage section 40, the rotating shutter member 90 does not rotate and serves to prevent the movement of toner from the toner cartridge 20K to the toner storage section 40.

<Control system configuration>
3 is a block diagram showing a schematic configuration of a control system of the image forming apparatus 100 according to the embodiment. The image forming apparatus 100 includes a control unit 110, a receiving unit 131, a toner amount detection unit 132, a cartridge detection unit 133, a drive control unit 120, a supply member drive unit 121, a drum drive unit 122, a belt drive unit 123, a fixing control unit 124, an exposure control unit 125, a voltage control unit 126, a fixing device 7, an LED head 2, a charging roller 12, a developing roller 41, a supply roller 42, a regulating blade 43, and a transfer roller 6d. The control unit 110 includes a toner supply control unit 111 and a toner remaining amount determination unit 112. The drive control unit 120, the fixing control unit 124, the exposure control unit 125, and the voltage control unit 126 may be part of the control unit 110. The control unit 110 is formed of a processing circuit such as a semiconductor integrated circuit, for example. The processing circuit may be composed of a processor such as a CPU (Central Processing Unit) and a memory serving as a storage device for storing a program, which is software executed by the processor.

When the image forming apparatus 100 receives a print instruction from a host device (not shown) at the receiving unit 131, it sends the print instruction to the control unit 110. When the control unit 110 receives the print instruction, it sends the print information to the drive control unit 120, the fixing control unit 124, the exposure control unit 125, and the voltage control unit 126, and issues an instruction for the print operation. When the drive control unit 120 receives an instruction from the control unit 110, it rotates the drum drive unit 122 and the belt drive unit 123 to rotate the photosensitive drum 11 and the drive roller 6b. When the voltage control unit 126 receives an instruction from the control unit 110, it controls the voltages applied to the charging roller 12, the developing roller 41, the supply roller 42, the regulating blade 43, and the transfer roller 6d. When the exposure control unit 125 receives an instruction from the control unit 110, it causes the LED head 2 to emit light. When the fixing control unit 124 receives an instruction from the control unit 110, it controls the temperature of the fixing unit 7. The toner remaining amount determination unit 112 determines whether the amount of toner in the toner storage unit 40 has decreased based on the detection result of the toner amount detection unit 132. If the toner remaining amount determination unit 112 determines that the amount of toner has decreased, it sends information to the toner supply control unit 111, which in turn issues an instruction to the drive control unit 120 to perform a toner supply operation. When the drive control unit 120 receives an instruction to perform a toner supply operation, it drives the supply member drive unit 121 to rotate the rotating shutter member 90, thereby supplying toner into the toner storage unit 40. The cartridge detection unit 133 is a detection unit that detects that the toner cartridge at the top of the toner storage unit 40 has been replaced.

In this embodiment, the control unit 110 performs intermittent operation control to control the supply member drive unit 121 and the stirring member drive unit so that, after it is detected (for example, immediately after) that the toner cartridge 20 has been replaced, a stirring supply period (for example, S3) in which the stirring operation by the stirring members 44, 45 and the supply operation by the rotating shutter member 90 are performed simultaneously is intermittently provided, and a stirring period (for example, S4) in which the stirring operation is performed but the supply operation is not performed is provided between adjacent stirring supply periods. In addition, it is preferable that the control unit 110 performs intermittent operation control so that the stirring supply period and the stirring period are alternately repeated. In addition, it is preferable that the control unit 110 sets the stirring supply period (for example, S3) per time to a first time, sets the stirring period (for example, S4) per time to a second time, and sets the second time to be equal to or longer than the first time. It is also preferable that the control unit 110 sets the mixing replenishment period (e.g., S3) per one time to a first time, sets the developer replenishment period (e.g., S1) other than immediately after it is detected that the toner cartridge 20 has been replaced to a third time, and sets the first time to a time equal to or less than the third time. Note that the control unit 110 may employ a control method in which the intermittent operation control is performed immediately after it is detected that the remaining amount of toner is at a toner empty level, which is a level at which the toner cartridge 20 needs to be replaced, and the toner cartridge 20 has been replaced with a new one.

"motion"
The printing process will be described. After applying a charging voltage to the charging roller 12 from the voltage control unit 126 to uniformly charge the surface of the photosensitive drum 11, the LED head 2 is caused to emit light in accordance with instructions from the exposure control unit 125 to form an electrostatic latent image on the surface of the photosensitive drum 11. Then, a developing voltage is applied from the voltage control unit 126 to the developing roller 41 on whose surface a thin layer of toner is formed, to develop the electrostatic latent image on the photosensitive drum 11. Here, a supply voltage and a regulating voltage are applied from the voltage control unit 126 to the supply roller 42 and the regulating blade 43 in order to uniformly form the thickness of the thin toner layer on the developing roller 41 and to set the charge amount of the toner in the thin toner layer to a predetermined value.

Next, a transfer voltage is applied to the transfer roller 6d by the voltage control unit 126 to transfer the toner image on the photosensitive drum 11 onto the recording medium P, and the toner image on the recording medium P is then fixed to the recording medium P by the fixing device 7. The fixed recording medium P is discharged outside the device by the discharge rollers 31, completing the printing operation. Any toner remaining on the photosensitive drum 11 that was not transferred is removed by a cleaning device. In addition, the surface potential of the photosensitive drum 11 is reset by exposure to static elimination light.

When the image forming apparatus is operated in a normal temperature and humidity environment using negatively charged toner, the applied voltage settings are, for example, -1050V for the charging roller 12, -200V for the developing roller 41, -300V for the supply roller 42, and -300V for the blade voltage of the regulating blade 43. When a charging voltage of a predetermined value or more is applied to the charging roller 12, the surface of the photosensitive drum 11 is charged, and the surface potential changes in proportion to the applied charging voltage. In this embodiment, when a charging voltage of -1050V is applied, the surface potential of the photosensitive drum 11 becomes -500V. Then, the potential of the electrostatic latent image formed by the light emission of the LED head 2 becomes -50V, and the toner from the developing roller 41 is reversely developed onto the electrostatic latent image. Note that if the toner D is a positively charged toner, the signs of the voltages of the various parts are reversed.

Figures 4(a) and (b) are diagrams for explaining the operation of detecting the toner amount in the toner storage unit 40. Figure 5 is a time chart for explaining the operation of detecting the toner amount in the toner storage unit 40. In the initial state (time t = 0), the toner amount detection member 46 is in the state shown in Figure 4(a). In Figure 4(a), the toner amount detection member 46 (or its center of gravity) is located at the lowest point of its rotation trajectory.

The toner amount detection member 46 rotates in the direction R46 with a rotation period T by receiving a driving force from the drum driving unit 122. The toner amount detection member 46 is rotated as if pushed up by the driving force from the drum driving unit 122, and reaches the top of its rotation locus after a time T/2 has elapsed (time t = T/2) as shown by the dashed line in FIG. 4(a). Then, the toner amount detection member 46 falls while rotating under its own weight. At this time, as shown in FIG. 4(a), when the amount of toner D in the toner storage unit 40 is small and the top surface of the toner is at a low position H1 (toner low), the toner amount detection member 46 does not receive much pressure from the toner D, so it falls under its own weight to the bottom point as shown by the solid line in FIG. 4(a), and reaches the bottom point at time t = T/2 + Δt (0 < Δt < T/2). At this time, the toner remaining amount determination unit 112 outputs a high-level signal. The control unit 110 detects the length of time during which the high-level signal is received (i.e., the residence time T1 below the toner amount detection member 46). Then, as shown in FIG. 5, the control unit 110 detects a toner low (a state in which toner is insufficient) when the residence time T1 is longer than a preset time Tlow.

On the other hand, when the top surface of the toner in the toner storage unit 40 is at a high position H2 (toner full), the toner pressure on the toner amount detection member 46 is high, so the toner amount detection member 46 rotates in synchronization with a drive unit (not shown) without falling under its own weight. The residence time T1 of the toner amount detection member 46 at the bottom detected by the toner remaining amount determination unit 112 is shorter the more toner accumulated in the toner storage unit 40, and when it is shorter than the set time Tlow, the toner remaining amount determination unit 112 determines that the toner is full (a state in which a sufficient amount of toner has accumulated).

The toner supply operation will now be described. When the toner remaining amount determination unit 112 detects a toner low, the toner supply control unit 111 instructs the drive control unit 120 to perform a toner supply operation, and the drive control unit 120 operates the supply member drive unit 121. This causes the rotating shutter member 90 to rotate, and while the rotating shutter member 90 is rotating, the toner in the toner cartridge 20 is continuously supplied to the toner storage unit 40. During this time, the drive control unit 120 operates the drum drive unit 122.

If the toner supply operation continues but the toner low judgment is repeated, the control unit 110 determines that the toner cartridge 20 is empty, and after printing a predetermined number of sheets, determines that the amount of toner is at the empty level, and prompts the user to replace the toner cartridge.

In this embodiment, the amount of toner in the toner storage unit 40 is set to 35 g when the toner is full, 33 g when the toner is low, and 29 g when the toner is empty. The amount of toner supplied by the rotation of the rotating shutter member 90 is 0.3 g/sec. However, these numerical values are merely examples, and other values may be used.

Figure 6 is a time chart for explaining the toner supply operation under normal circumstances. Here, normal circumstances refers to any time other than immediately after the replacement of the toner cartridge. When the toner remaining amount determination unit 112 determines that the toner is low while the drum drive unit 122 is being driven, the drive control unit 120 operates the supply member drive unit 121 to rotate the rotating shutter member 90 as a supply member based on a command from the control unit 110, and supplies new toner from the toner cartridge 20 to the toner storage unit 40. In this embodiment, in the toner supply operation under normal circumstances, it is necessary to supply 2 g (= 35 g - 33 g) of toner to change from the toner low state to the toner full state, so that the supply member drive unit 121 is driven for a period S1 (for example, 7 seconds) to rotate the rotating shutter member 90 and supply approximately 2 g (≒ 0.3 g / sec x 7 seconds). However, if the toner remaining amount determination unit 112 detects a toner full state during the period S1, the drive control unit 120 stops the supply member drive unit 121 at that time point based on a command from the control unit 110. Also, if a toner full state cannot be detected during the period S1, the drive control unit 120 drives the supply member drive unit 121 again based on a command from the control unit 110. In this embodiment, the drum drive unit 122 rotates the photosensitive drum 11, and the stirring members 44 and 45 operate in conjunction with the rotation of the photosensitive drum 11. The drum drive unit 122 stops after the toner supply operation is completed and the period Q has elapsed. The period Q can be appropriately set to a time period longer than 0 seconds. The period Q is, for example, 1 second. Note that the length of the period S1 described in the normal toner supply operation is an example, and other values may be used.

Figure 7 is a table showing the results of an evaluation of the occurrence of vertical bands, which is the effect on printed images of toner replenishment and toner stirring performed immediately after replacing the toner cartridge 20. Figure 7 shows the results of visually checking printed images after five types of toner replenishment and toner stirring: Comparative Examples C1, C2, and C3 and Examples E1 and E2. In Figure 7, items with clear vertical bands are marked with an "X" indicating poor print quality, items with slight vertical bands are marked with a "△" indicating slightly poor print quality, and items with no vertical bands are marked with a "O" indicating good print quality.

Comparative Example C1 is an example of a case where the toner supply stirring operation performed immediately after replacing the toner cartridge 20 is the operation of the conventional technology. The toner supply stirring operation of Comparative Example C1 is shown in FIG. 8 described later. The toner supply stirring operation performed immediately after replacing the toner cartridge 20 of Comparative Example C2 is shown in FIG. 9 described later. The toner supply stirring operation performed immediately after replacing the toner cartridge 20 of Comparative Example C3 is shown in FIG. 10 described later. Example E1 is an example of a case where the toner supply stirring operation performed immediately after replacing the toner cartridge 20 is the operation of this embodiment. The toner supply stirring operation of Example E1 is shown in FIG. 11 described later. Example E2 is an example of a case where the toner supply stirring operation performed immediately after replacing the toner cartridge 20 is the operation of this embodiment. The toner supply stirring operation of Example E2 is shown in FIG. 12 described later.

Figure 8 is a time chart showing the toner supply stirring operation of Comparative Example C1 executed immediately after replacing the toner cartridge 20. In order to change from a toner empty state to a toner full state, 6 g (= 35 g - 29 g) of toner needs to be replenished, so the supply member driving unit 121 is driven during the period S2 (for example, 20 seconds) to rotate the rotating shutter member 90 and supply approximately 6 g (≒ 0.3 g / sec x 20 seconds) of toner. However, if the toner remaining amount determination unit 112 detects a toner full state during the period S2, the drive control unit 120 stops the supply member driving unit 121 at that time based on a command from the control unit 110. Also, if a toner full state cannot be detected during the period S2, the drive control unit 120 drives the supply member driving unit 121 again based on a command from the control unit 110. In Comparative Example C1, the drum driving unit 122 rotates the photosensitive drum 11, but the stirring members 44 and 45 operate in conjunction with the rotation of the photosensitive drum 11. The drum drive unit 122 stops after the toner refill operation has ended and a period Q has elapsed. The period Q can be set appropriately to a time period longer than 0 seconds, for example, 1 second. As shown in the table in FIG. 7, in the case of comparative example C1, clear vertical bands appeared in the printed image. This is thought to be because the fluidity of the toner remaining in the toner storage unit 40 has decreased and the fluidity of the new toner that has been replenished is high, so the toner is not mixed uniformly by the stirring of the stirring members 44 and 45.

9 is a time chart showing the toner supply stirring operation of Comparative Example C2 executed immediately after replacing the toner cartridge 20. Since 6 g of toner needs to be supplied to change from the toner empty state to the toner full state, the supply member driving unit 121 is driven during the period S3 (e.g., 7 seconds) to rotate the rotating shutter member 90 in the supply stirring operation, and the stirring operation is continued and the supply operation is interrupted during the period S4 (S3>S4) to execute the supply stirring operation a predetermined number of times (e.g., 3 times), and about 6 g (≒0.3 g/sec x 7 sec x 3 times) of toner is supplied. If the toner remaining amount determination unit 112 detects the toner full during the period S3, the drive control unit 120 stops the supply member driving unit 121 at that time based on a command from the control unit 110. Also, if the toner full cannot be detected during the three periods S3, the drive control unit 120 drives the supply member driving unit 121 again based on a command from the control unit 110. In comparative example C2, the drum drive unit 122 rotates the photosensitive drum 11, but the stirring members 44, 45 operate in conjunction with the rotation of the photosensitive drum 11. The drum drive unit 122 stops after the toner supply operation is completed and a period Q has elapsed. As shown in the table in FIG. 7, in the case of comparative example C2, slight vertical bands occurred in the printed image. This is thought to be because the period S4 during which stirring is performed by the stirring members 44, 45 is short, and toners with different fluidities are not mixed uniformly.

Figure 10 is a time chart showing the toner supply stirring operation of Comparative Example C3 executed immediately after replacing the toner cartridge 20. In order to change from a toner empty state to a toner full state, it is necessary to supply 6 g of toner. Therefore, during a period S2 (e.g., 20 seconds), the supply member driving unit 121 is driven to rotate the rotating shutter member 90, and the replenishing stirring operation is executed once for a predetermined period (e.g., 22 seconds) by continuing the stirring operation and interrupting the replenishing operation. However, if the toner remaining amount determination unit 112 detects a toner full state during the period S2, the drive control unit 120 stops the supply member driving unit 121 at that time based on a command from the control unit 110. Also, if a toner full state cannot be detected during the period S2, the drive control unit 120 drives the supply member driving unit 121 again based on a command from the control unit 110. In Comparative Example C3, the drum driving unit 122 rotates the photosensitive drum 11, but the stirring members 44 and 45 operate in conjunction with the rotation of the photosensitive drum 11. The drum drive unit 122 stops after the toner supply operation is completed and a period Q has elapsed. As shown in the table in FIG. 7, in the case of comparative example C3, slight vertical bands occurred in the printed image. This is thought to be because toners with different fluidities are not mixed uniformly when a large amount of new toner is supplied in one toner supply operation, even if the period S2 during which stirring is performed by the stirring members 44 and 45 is extended.

11 is a time chart showing the toner supply stirring operation of embodiment E1 executed immediately after replacing the toner cartridge 20. Since it is necessary to supply 6 g of toner to change from the toner empty state to the toner full state, the supply member driving unit 121 is driven during a period S3 (e.g., 7 seconds) to rotate the rotary shutter member 90, and the stirring operation is continued and the supply operation is interrupted during a period S4 to execute the replenishing stirring operation a predetermined number of times (e.g., 3 times). In embodiment E1, in order to prevent vertical bands that occur immediately after replacing the toner cartridge 20 after the toner empty state, a period in which both the toner supply operation and the stirring operation are performed and a period in which only stirring is performed are alternately provided during the period from the toner empty state to the toner full state. If the operating period of the supply member driving unit during normal toner supply operation is S1 (shown in Figure 6), the operating period of the supply member driving unit 121 after replacement of the toner cartridge 20 is S3, and the period during which the supply member driving unit 121 is stopped and only the drum driving unit 122 is driven is S4, in embodiment E1, control is performed to satisfy the following relationships (1) and (2).
S3≦S1 ... (1)
S3 = S4 ... (2)

As shown in formula (1), the operating period S3 of the supply member driving unit 121 is set to be equal to or shorter than the normal toner supply operation period S1. This is to prevent uneven mixing of the deteriorated toner and new toner by making the period S1 during which there are no problems with the mixture of the deteriorated toner and new toner the longest. Also, as shown in formula (2), referring to the results of comparative example C2 in FIG. 7, the operating period S3 of the supply member driving unit 121 is set to be equal to the period S4 during which only the drum driving unit 122 is driven. As shown in the table in FIG. 7, in the case of example E1, a good quality image was obtained with no vertical bands in the printed image.

12 is a time chart showing the toner supply stirring operation of embodiment E2 executed immediately after replacing the toner cartridge 20. Since it is necessary to supply 6 g of toner to change from the toner empty state to the toner full state, the supply member driving unit 121 is driven during a period S3 (e.g., 7 seconds) to rotate the rotary shutter member 90, and the stirring operation is continued and the supply operation is interrupted during a period S4 to execute the replenishing stirring operation a predetermined number of times (e.g., 3 times). In embodiment E2, in order to prevent vertical bands that occur immediately after replacing the toner cartridge 20 after the toner empty state, a period in which both the toner supply operation and the stirring operation are performed and a period in which only stirring is performed are alternately provided during the period from the toner empty state to the toner full state. If the operating period of supply member driving unit 121 during normal toner supply operation is S1, the operating period of supply member driving unit 121 after replacement of toner cartridge 20 is S3, and the period during which supply member driving unit 121 is stopped and only drum driving unit 122 is driven is S4, in embodiment E2, control is performed to satisfy the following relationships (1) and (3).
S3≦S1 ... (1)
S3<S4 ... (3)

As shown in formula (1), the operation period S3 of the supply member driving unit 121 is set to be equal to or shorter than the normal toner supply operation period S1. This is to prevent uneven mixing of the deteriorated toner and the new toner by making the period S1 during which there is no problem with the mixture of the deteriorated toner and the new toner the longest. Also, as shown in formula (3), referring to the results of comparative example C2 in FIG. 7, the period S4 during which only the drum driving unit 122 is driven is set to be longer than the operation period S3 of the supply member driving unit 121. As shown in the table in FIG. 7, in the case of embodiment E2, it was possible to obtain a good quality image without vertical bands in the printed image. Referring to the results in FIG. 8, the operation period S3 of the supply member driving unit 121 is set to be shorter than the period S4 during which only the drum driving unit 122 is driven. As shown in the table in FIG. 7, in the case of embodiment E2, although the total driving time is long, it was possible to obtain a good quality image without vertical bands in the printed image.

"effect"
As described above, according to this embodiment (for example, Examples E1 and E2), during the period from the toner empty state to the toner full state, a replenishment and mixing period in which both toner replenishment and mixing operations are performed is alternated with a mixing period in which replenishment is stopped and only mixing is performed. This eliminates unevenness in the mixing of deteriorated toner in the toner storage section 40 and new toner replenished from the toner cartridge 20, thereby preventing image defects such as vertical bands.

In addition, in recent years, toner melting points have been lowered for the purpose of energy saving, so the toner in the toner storage section 40 is easily deteriorated. As a result, differences in the fluidity and charging characteristics of the toner are likely to occur between the deteriorated toner in the toner storage section 40 and the new toner in the toner cartridge 20. The toner in the toner storage section 40 is stirred by the stirring members 44 and 45 to mix the deteriorated toner in the toner storage section 40 with the new toner supplied from the toner cartridge 20. However, when there is little toner in the toner storage section 40 and a large proportion of new toner is supplied from the toner cartridge 20, such as when replacing the toner cartridge 20 after the toner is empty, the toner cannot be mixed uniformly by stirring with the stirring members 44 and 45, and the difference in toner characteristics appears as uneven density such as vertical bands on the printed image. In this embodiment, in order to prevent vertical bands that occur immediately after replacing the toner cartridge 20 after the toner is empty, the period from the toner empty state to the toner full state is alternated between periods in which both the toner supply operation and the stirring operation are performed and periods in which only stirring is performed, thereby preventing the occurrence of image defects while suppressing an increase in the total driving time.

Note that although the image forming device of this disclosure has been described as a printer, it can also be applied to a copier or multifunction device, etc.

1, 1K, 1Y, 1M, 1C image forming unit, 10, 10K, 10Y, 10M, 10C process unit, 11 photosensitive drum (image carrier), 20, 20K, 20Y, 20M, 20C toner cartridge (developer storage section), 40 toner storage section (developer storage section), 44, 45 stirring member, 90 rotating shutter member (supply member), 100 image forming device, 110 control section, 121 supply member drive section, 122 drum drive section (stirring member drive section), 132 toner amount detection section, 133 cartridge detection section, D toner (developer), S3 stirring supply period, S4 stirring period.

Claims (7)

a developer container that contains a developer to be supplied to an image carrier;
a supply member that supplies new developer from a developer storage unit attached to the developer accommodating unit to the developer accommodating unit;
a stirring member that stirs the developer in the developer accommodating portion;
a supply member driving unit that causes the supply member to perform the supplying operation;
an agitation member driving unit that causes the agitation member to perform the agitation operation;
a detection unit for detecting that the developer storage unit has been replaced;
a control unit that performs intermittent operation control to control the supply member driving unit and the stirring member driving unit so that, after it is detected that the developer storage unit has been replaced, a stirring supply period during which the stirring operation and the supply operation are simultaneously performed is intermittently provided, and a stirring period during which the stirring operation is performed and the supply operation is not performed is provided during the stirring supply period;
An image forming apparatus comprising: The image forming apparatus according to claim 1 , wherein the control unit executes the intermittent operation control such that the mixing and supplying period and the mixing period are alternately repeated. 3. The image forming apparatus according to claim 1, wherein the control unit sets the mixing period per one time to a first time, sets the mixing period per one time to a second time, and sets the second time to be equal to or longer than the first time. 3. The image forming apparatus according to claim 1, wherein the control unit sets the mixing replenishment period per one time to a first time, sets the developer replenishment period other than immediately after it is detected that the developer storage unit has been replaced to a third time, and sets the first time to be equal to or shorter than the third time. The image forming apparatus according to claim 1 or 2, characterized in that the supply member is a rotating shutter member that is rotatably supported in the developer accommodating portion and that performs a supply operation of new developer from the developer storage portion to the developer accommodating portion by rotating. a developer amount detection unit that detects the amount of developer in the developer storage unit,
3. The image forming apparatus according to claim 1, wherein the control unit executes the intermittent operation control immediately after it is detected that the amount of the developer is at an empty level, which is a level at which the developer storage unit needs to be replaced, and the developer storage unit has been replaced. a developer container that contains a developer to be supplied to an image carrier;
a supply member that supplies new developer from a developer storage unit attached to the developer accommodating unit to the developer accommodating unit;
a stirring member that stirs the developer in the developer accommodating portion;
a supply member driving unit that causes the supply member to perform the supplying operation;
an agitation member driving unit that causes the agitation member to perform the agitation operation;
a detection unit for detecting that the developer storage unit has been replaced;
A control method executed by an image forming apparatus having
a control method for an image forming apparatus, comprising: controlling the supply member driving unit and the stirring member driving unit so as to intermittently provide a stirring supply period during which the stirring operation and the supply operation are performed simultaneously after it is detected that the developer storage unit has been replaced, and to provide a stirring period during which the stirring operation is performed but the supply operation is not performed during the stirring supply period.

Images