JP2020086165A - Image formation device - Google Patents

Abstract

To provide an image formation device capable of performing a toner replenishment operation in a developing unit at an appropriate timing.SOLUTION: A developing unit 52 has a replenishment port 67 and a sensor 64. The replenishment port 67 receives replenishment of a toner from a feeding unit 69 on the downstream side of a consumption unit 62. The sensor 64 detects the toner concentration of a developer on the downstream side of the replenishment port 67, on the upstream side of the consumption unit 62. In a first mode for checking the status of the developing unit 52, a controlling unit 100 measures first time required for the developer to be transferred from the replenishment port 67 to the arrangement position of the sensor 64, and predicts second time required for the developer to be transferred from the arrangement position of the sensor 64 to the replenishment port 67 via the consumption unit 62 on the basis of the first time. In a second mode for forming an image, the controlling unit 100 controls the feeding unit 69 so that the feeding unit 69 starts operation after a lapse of delay time equivalent to the second time from the time when a detection result of the sensor 64 indicates a decrease in the toner concentration.SELECTED DRAWING: Figure 2

Description

The present invention relates to an image forming apparatus.

The image forming apparatus described in Patent Document 1 includes a developing unit, a replenishing unit, and a control unit. The developing unit develops the electrostatic latent image into a toner image by using a two-component developer containing toner and carrier. The replenishing unit replenishes the toner to the developing unit. The control unit controls the operation of the replenishment unit so that the replenishment unit starts the operation after a fixed delay time from the time when the detection result of the sensor indicates the decrease of the toner concentration. The fixed delay time corresponds to the time required while the developer is transferred from the position where the sensor is provided to the supply port in the developing section.

JP, 2010-91784, A

The actual time required for the developer to be transferred from the position where the sensor is provided to the replenishment port in the developing section changes according to the fluctuation of the conditions including temperature and humidity. However, since the delay time related to the operation of the replenishing unit is fixed in the past, the timing of the toner replenishing operation is not always appropriate.

In view of the above circumstances, it is an object of the present invention to provide an image forming apparatus that performs a toner replenishing operation in a developing unit at an appropriate timing.

The image forming apparatus of the present invention includes a developing unit, a replenishing unit, and a control unit. The developing unit develops the electrostatic latent image into a toner image using a developer containing toner. The replenishing unit replenishes the toner to the developing unit. The control unit controls the operation of the supply unit. The developing unit includes a container, a stirring member, a consuming unit, a supply port, and a sensor. The container contains the developer. The stirring member transfers the developer along the circulation path while stirring the developer in the container. The consumption section consumes toner for the development in the circulation path. The replenishing port receives replenishment of toner from the replenishing unit on the downstream side of the consuming unit. The sensor detects the toner concentration of the developer on the downstream side of the replenishing port and the upstream side of the consuming unit. In the first mode of checking the state of the developing unit, the control unit measures the first time required for the developer to be transferred from the replenishment port to the position where the sensor is provided, and the first time On the basis of the above, the second time required while the developer is transferred from the position where the sensor is disposed to the replenishment port through the consuming portion is predicted. In the second mode for forming an image, the control unit causes the replenishment unit to start operation after a delay time corresponding to the second time from the time when the detection result of the sensor indicates the decrease of the toner concentration. To control the replenishment section.

According to the present invention, it is possible to provide the image forming apparatus that performs the toner replenishing operation in the developing unit at an appropriate timing.

FIG. 1 illustrates an example of an image forming apparatus according to an exemplary embodiment of the present invention. It is a figure which shows an example of an internal structure of a developing part. FIG. 3 is a diagram showing a developer circulation path divided into two sections. It is a flow chart which shows an example of processing of a control part. 7 is a flowchart illustrating an example of a developing unit check process. (A), (b), and (c) are toner concentration distribution diagrams at different times.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 6. In the drawings, the same or corresponding parts will be denoted by the same reference symbols and description thereof will not be repeated. In this embodiment, the X axis, the Y axis, and the Z axis are orthogonal to each other, the X axis and the Y axis are parallel to the horizontal plane, and the Z axis is parallel to the vertical line.

First, an image forming apparatus 1 according to the embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating an example of the image forming apparatus 1 according to the embodiment. In this embodiment, the image forming apparatus 1 is a printer.

As shown in FIG. 1, the image forming apparatus 1 includes a feeding unit 10, a conveying unit 20, an image forming unit 30, a toner supplying unit 80, a discharging unit 90, a driving source 95, and a control unit 100. In the image forming apparatus 1, a two-component developer is used. That is, the developer contains the toner and the carrier. The carrier is, for example, a magnetic carrier.

The control unit 100 controls each element of the image forming apparatus 1, such as the feeding unit 10, the transporting unit 20, the image forming unit 30, the toner supplying unit 80, the discharging unit 90, and the driving source 95. For example, the control unit 100 includes a processor such as a CPU (Central Processing Unit) and a storage unit. The storage unit includes a main storage device such as a semiconductor memory and an auxiliary storage device such as a semiconductor memory or a hard disk drive.

The feeding unit 10 includes a cassette 11 that stores a plurality of sheets P. The sheet P is, for example, a sheet made of paper or synthetic resin. The feeding unit 10 feeds the sheet P from the cassette 11 to the conveyance unit 20. The transport unit 20 includes a plurality of transport rollers and transports the sheet P to the image forming unit 30. The image forming unit 30 forms an image (a color image in this embodiment) on the sheet P. The transport unit 20 transports the sheet P on which the image is formed to the discharge unit 90. The discharge unit 90 discharges the sheet P to the outside of the image forming apparatus 1.

The image forming unit 30 includes an exposure unit 31, an M unit 32M, a C unit 32C, a Y unit 32Y, a BK unit 32BK, an intermediate transfer belt 33, a secondary transfer roller 34, and a fixing unit 35.

The exposure unit 31 irradiates each of the M units 32M to BK units 32BK with light based on image data to form an electrostatic latent image on each of the M units 32M to BK units 32BK. The M unit 32M forms a magenta toner image based on the electrostatic latent image. The C unit 32C forms a cyan toner image based on the electrostatic latent image. The Y unit 32Y forms a yellow toner image based on the electrostatic latent image. The BK unit 32BK forms a black toner image based on the electrostatic latent image.

On the outer surface of the intermediate transfer belt 33, toner images of four colors are transferred in a superimposed manner to form a color toner image, that is, a color image. The secondary transfer roller 34 transfers the color image formed on the outer surface of the intermediate transfer belt 33 to the sheet P. The fixing unit 35 heats and pressurizes the sheet P to fix the color image on the sheet P.

Each of the M unit 32M to the BK unit 32BK includes a photosensitive drum 50, a charger 51, a developing unit 52, a primary transfer roller 53, and a cleaner 54.

The photoconductor drum 50 rotates around the rotation axis. The charger 51 charges the peripheral surface of the photoconductor drum 50. The peripheral surface of the photoconductor drum 50 is irradiated with light by the exposure unit 31 to form an electrostatic latent image. The developing unit 52 attaches toner to the electrostatic latent image, develops the electrostatic latent image, and forms a toner image on the peripheral surface of the photosensitive drum 50. That is, the developing unit 52 develops the electrostatic latent image with the toner. The primary transfer roller 53 transfers the toner image formed on the peripheral surface of the photosensitive drum 50 to the outer surface of the intermediate transfer belt 33. The cleaner 54 removes the toner remaining on the peripheral surface of the photoconductor drum 50.

The toner supply unit 80 includes a toner container 80M, a toner container 80C, a toner container 80Y, and a toner container 80BK. The toner container 80M stores magenta toner to be supplied to the developing unit 52 of the M unit 32M. The toner container 80C stores the cyan toner to be supplied to the developing unit 52 of the C unit 32C. The toner container 80Y stores the yellow toner to be supplied to the developing unit 52 of the Y unit 32Y. The toner container 80BK contains black toner to be supplied to the developing unit 52 of the BK unit 32BK.

The drive source 95 is, for example, a motor and is connected to a plurality of driven parts via a gear train. The plurality of driven parts include the photosensitive drum 50, the developing part 52, the primary transfer roller 53, the intermediate transfer belt 33, the secondary transfer roller 34, the fixing unit 35, the feeding part 10, the transport part 20, and the discharging part 90. including. Then, the drive source 95 drives the plurality of driven parts based on the control signal output from the control part 100. Specifically, each driven part is a rotating body or includes a rotating body, and when the rotating shaft of the drive source 95 is rotated, each rotating body rotates via the gear train.

Next, the developing unit 52 will be described with reference to FIGS. 1 and 2. FIG. 2 is a diagram showing an example of the internal structure of the developing unit 52. In FIG. 2, the developing unit 52 of the M unit 32M is shown. The structure of the developing unit 52 of the C unit 32C to the BK unit 32BK is the same as the structure of the developing unit 52 of the M unit 32M, and the description thereof will be omitted.

As shown in FIG. 1, the developing unit 52 includes a first stirring member 60, a second stirring member 61, a magnetic roller 62, and a developing roller 63. As shown in FIG. 2, the developing unit 52 further includes a sensor 64 and a container 65. Incidentally, in FIG. 2, the developing roller 63 is omitted for the sake of simplification of the drawing.

The container 65 accommodates the first stirring member 60, the second stirring member 61, the magnetic roller 62, and the developing roller 63. The container 65 further contains a developer. The container 65 has a partition wall 66. The inside of the container 65 is partitioned by a partition wall 66 into a first stirring chamber 65a and a second stirring chamber 65b. Inside the container 65, a passage 65c and a passage 65d are formed at both ends of the partition wall 66. A circulation path 75 for the developer is formed in the container 65 by the first stirring chamber 65a, the passage 65c, the second stirring chamber 65b, and the passage 65d.

The first stirring member 60 is arranged in the first stirring chamber 65a, and the second stirring member 61 is arranged in the second stirring chamber 65b. In the present embodiment, each of the first stirring member 60 and the second stirring member 61 is a screw. Each of the first stirring member 60 and the second stirring member 61 is driven by the driving source 95 to rotate. In the present embodiment, the time for which the first stirring member 60 makes one rotation (that is, the rotation cycle of the first stirring member 60) and the time for which the second stirring member 61 makes one rotation (that is, the rotation cycle of the second stirring member 61) Is the same as.

The first stirring member 60 and the second stirring member 61 transfer the developer along the circulation path 75 while stirring the developer in the container 65. While the developer is transported in the circulation direction D1 to the circulation direction D4, the toner in the developer is charged. The toner is conveyed to the magnetic roller 62 by the second stirring member 61 together with the carrier. The toner is further attached to the peripheral surface of the photosensitive drum 50 via the developing roller 63. As a result, the electrostatic latent image formed on the peripheral surface of the photosensitive drum 50 is developed and a toner image is formed. The magnetic roller 62 and the developing roller 63 correspond to an example of a "consumer".

The sensor 64 is a magnetic permeability sensor in this embodiment. The magnetic permeability sensor detects the magnetic permeability of the developer in the developing section 52. Then, based on the magnetic permeability, the mixing ratio of the toner of the developer contained in the developing unit 52 and the carrier, that is, the toner concentration D is obtained. In the present embodiment, the sensor 64 is arranged outside the bottom plate forming the first stirring chamber 65a at a position downstream of the longitudinal center of the first stirring chamber 65a in the circulation direction D1 of the first stirring chamber 65a.

Next, the replenishment of toner to the developing unit 52 will be described with reference to FIG. The developing section 52 has a toner supply port 67. The supply port 67 is formed in the container 65 of the developing unit 52. The supply port 67 is arranged above the first stirring chamber 65a at a position upstream of the longitudinal center of the first stirring chamber 65a in the circulation direction D1 of the first stirring chamber 65a. That is, the supply port 67 receives the supply of toner on the downstream side of the magnetic roller 62, which is an example of a consumption unit. On the other hand, the sensor 64 detects the toner concentration of the developer on the downstream side of the supply port 67 and the upstream side of the magnetic roller 62.

The image forming apparatus 1 further includes a replenishing unit 69 corresponding to each of the toner containers 80M to 80BK. Note that in FIG. 2, the replenishing unit 69 corresponding to the toner container 80M is shown. The configuration of the replenishing unit 69 corresponding to each of the toner container 80C to the toner container 80BK is the same as the configuration of the replenishing unit 69 corresponding to the toner container 80M, and thus the description thereof will be omitted.

The replenishing unit 69 replenishes the toner to the developing unit 52 via the replenishing port 67. Specifically, the replenishment unit 69 includes a replenishment motor 70 and a conveyance member 71. The control unit 100 controls the operation of the supply unit 69. The supply motor 70 rotates the transport member 71 based on the control signal output from the control unit 100. In the present embodiment, the transport member 71 is a screw. By the rotation of the transport member 71, the toner accommodated in the toner container 80M is transported toward the replenishment port 67, drops from the replenishment port 67, and is replenished to the circulation path 75.

A communication unit 96 is connected to the control unit 100, and the control unit 100 receives an image forming instruction via the communication unit 96.

Next, the length of the circulation path 75 will be described with reference to FIGS. 2 and 3. The length of the circulation path 75 is measured along the center line of the circulation path 75. FIG. 3 is a diagram showing the circulation path 75 divided into two sections.

As shown in FIG. 3, the circulation path 75 is divided into a first section and a second section. The first section is a section from the supply port 67 to the sensor 64. The second section is a section from the sensor 64 to the supply port 67.

The developer flows into the first section having the length L1 over the first time T1. The first time T1 is a time required while the developer is transferred from the supply port 67 to the position where the sensor 64 is provided. The developer flows into the second section having the length L2 for the second time T2. The second time T2 is a time required while the developer is transferred from the position where the sensor 64 is disposed to the replenishment port 67 via the second stirring chamber 65b.

The developer circulates in the circulation path 75 having a length L over a time T. Therefore,
L=L1+L2 (1)
T=T1+T2 (2)
Is. Since the toner advection velocity in the first section and the toner advection rate in the second section are the same,
L1/T1=L2/T2 (3)
Holds. From equation (3),
T2=(L2/L1)T1 (4)
Holds. Further, from the formulas (1) and (4),
T2={(L-L1)/L1}T1 (5)
Holds.

The length L of one round of the circulation path 75 and the length L1 of the first section are known and unchanged when the developing section 52 is specified. Therefore, the second time T2 can be predicted by the calculation of the equation (5) based on the measurement result of the first time T1.

L1=L2=L/2 (6)
If Eq. (5) and Eq. (6) are satisfied,
T1=T2=T/2 (7)
Holds. The second time T2 matches the first time T1 and also matches half of the time T required for one round of the developer.

Next, the processing of the control unit 100 will be described with reference to FIGS. FIG. 4 is a flowchart showing an example of processing of the control unit 100. FIG. 5 is a flowchart showing an example of the developing unit check process in FIG.

Step S100: As shown in FIG. 4, the control unit 100 determines whether or not an image formation instruction is received via the communication unit 96. When control unit 100 receives the image formation instruction (YES in step S100), the process of control unit 100 proceeds to step S102. At this point, the first stirring member 60 and the second stirring member 61 start rotating. When the control unit 100 has not received the image formation instruction (NO in step S100), the process of the control unit 100 returns to step S100.

Step S102: The control section 100 calls the subroutine of the developing section check processing shown in FIG. As a result, the first mode processing for checking the state of the developing unit 52 starts.

Step S200: As shown in FIG. 5, the control unit 100 determines whether or not the detection result of the sensor 64 indicates that the toner density D is uniform. If the output change of the sensor 64 within a certain period of time is minute, it is determined that the toner density D is uniform. If the toner density D is uniform (YES in step S200), the process of the control unit 100 proceeds to step S202. If the toner density D is not uniform (NO in step S200), the process of the controller 100 returns to step S200.

Step S202: The control unit 100 controls the replenishment unit 69 so that a small amount of toner for checking is fed to the replenishment port 67.

Step S204: The control unit 100 measures the time until the toner density D detected by the sensor 64 reaches the maximum value as the first time T1.

Step S206: The control unit 100 predicts the second time T2 required to transfer the developer from the sensor 64 to the replenishment port 67 by using the formula (5).

Step S208: The control unit 100 sets the second time T2 as the delay time DL of the toner replenishment control. When the process of step S208 is completed, the process of the control unit 100 returns to step S104 of FIG. As a result, the second mode processing for forming an image starts.

Step S104: As shown in FIG. 4, the control unit 100 causes the feeding unit 10, the transport unit 20, the image forming unit 30, the toner supply unit 80, the discharge unit 90, and the drive source 95 to execute image formation. Each element of the image forming apparatus 1 as described above is controlled.

Step S106: The control unit 100 determines whether or not the detection result of the sensor 64 indicates that the toner density D has decreased. If the change in the output of the sensor 64 within a fixed time is larger than the threshold value, it is determined that the toner density D has decreased. If the toner density D has decreased (YES in step S106), the process of the control unit 100 proceeds to step S108. If the toner density D has not decreased (NO in step S106), the process of the control unit 100 returns to step S106.

Step S108: The control unit 100 controls the replenishment unit 69 so that the replenishment unit 69 starts the operation after the delay time DL determined in step S208 from the time when the detection result of the sensor 64 indicates the decrease of the toner concentration D. Control.

Step S110: The control unit 100 determines whether the image formation is completed. If the image formation is completed (YES in step S110), the process of the control unit 100 is completed. After a certain period of time, the first stirring member 60 and the second stirring member 61 stop rotating. If the image formation is not completed (NO in step S110), the process of the control unit 100 returns to step S100.

Finally, with reference to FIG. 3, FIG. 6A, FIG. 6B, and FIG. 6C, how the toner density D changes in the developing section check process will be described. FIGS. 6A, 6B, and 6C are toner concentration distribution diagrams at different times. The horizontal axis represents the distance E measured from a certain reference point along the circulation path 75. The vertical axis represents the toner density D.

FIG. 6A is a toner concentration distribution diagram at the time when the toner concentration D becomes uniform. The supply port 67 is located at the distance E1 and the sensor 64 is located at the distance E2. The difference between the distance E1 and the distance E2 is the length L1 described in FIG. In FIG. 6A, the toner density D shows a constant value DS at any position of the distance E. By rotating the first stirring member 60 and the second stirring member 61 for a fixed time, a uniform toner concentration distribution is realized.

FIG. 6B is a toner concentration distribution chart at the time when a small amount of toner for checking is fed into the replenishing port 67. The toner concentration D shows a peak of the maximum value DP1 at the position of the supply port 67. The amount of toner in the container 65 is about 20 grams, while the amount of toner for checking is, for example, ten and several milligrams. By changing the toner concentration D at the replenishing port 67, the change of the toner concentration D becomes remarkable by introducing the check toner into the replenishing port 67 after the toner concentration D becomes uniform.

FIG. 6C is a toner concentration distribution chart at the time when the peak of the toner concentration D reaches the position of the sensor 64. The toner density D shows a peak of the maximum value DP2 at the position of the sensor 64. The maximum value DP2 in FIG. 6(c) is smaller than the maximum value DP1 in FIG. 6(b). Further, the peak width ΔE2 of FIG. 6C is larger than the peak width ΔE1 of FIG. 6B. This is a result of diffusion due to advection of the developer.

The first time T1 measured in this embodiment corresponds to the time from the time point of FIG. 6(b) to the time point of FIG. 6(c). Since the measurement of the first time T1 can be finished at the time when the toner density D detected by the sensor 64 shows the maximum value, the accurate measurement of the first time T1 becomes possible.

According to the present embodiment, the delay time DL of the toner replenishing operation changes according to the measurement result of the first time T1, so that the toner replenishing operation is performed in the developing unit 52 at an appropriate timing. As a result, even if the toner concentration D is partially reduced in the developing section 52 due to the execution of image formation, the uniform distribution of the toner concentration D can be quickly recovered.

Further, according to the present embodiment, the control unit 100 performs the operation in the first mode for checking the state of the developing unit 52 after receiving the image formation instruction and before starting the execution of the image formation in the second mode. Run. As a result, the state of the developer immediately before the image formation is correctly reflected in the timing of the toner replenishing operation.

Since the above description of each embodiment describes preferred embodiments of the present invention, various technically preferable limitations may be attached, but the technical scope of the present invention is not limited to the present invention. Unless otherwise specified, the present invention is not limited to these embodiments. That is, the constituent elements in the above-described embodiments can be appropriately replaced with existing constituent elements and the like, and various variations including combinations with other existing constituent elements are possible. The description of the above embodiments does not limit the contents of the invention described in the claims.

(1) In this embodiment, the image forming apparatus 1 is a color printer that uses four color developers, as shown in FIG. However, the image forming apparatus 1 may be a color printer that uses developers of plural colors other than four colors. Further, the image forming apparatus 1 may be a printer that uses a monochrome developer. Further, the image forming apparatus 1 is not limited to a printer, and is, for example, a copying machine, a facsimile, or a multifunction machine.

(2) In the present embodiment, as shown in FIG. 4, the developing unit check process is executed every time the control unit 100 receives an image forming instruction, but the present invention is not limited to this. The developing unit check process may be executed once each time the image forming instruction is received a plurality of times.

(3) In the present embodiment, as shown in FIG. 4, the developing unit check process is executed before the image formation is executed, but the present invention is not limited to this. After execution of image formation, the developing unit check process may be executed as preparation for the next image formation.

The present invention can be used in the field of image forming apparatuses.

1 Image Forming Device 52 Developing Unit 60 First Stirring Member (Stirring Member)
61 Second stirring member (stirring member)
62 Magnetic Roller (Consumer)
63 developing roller (consumer)
64 sensor 65 container 67 supply port 69 supply unit 75 circuit 100 control unit

Claims (4)

A developing unit that develops an electrostatic latent image into a toner image using a developer containing toner,
A replenishing section for replenishing toner to the developing section,
A control unit for controlling the operation of the replenishment unit,
The developing unit is
A container containing the developer,
A stirring member that transfers the developer along the circulation path while stirring the developer in the container;
A consumption unit that consumes toner for the development in the circulation path;
A replenishing port for replenishing toner from the replenishing unit on the downstream side of the consuming unit
A sensor for detecting the toner concentration of the developer on the downstream side of the replenishment port and on the upstream side of the consuming portion,
In the first mode of checking the state of the developing unit, the control unit measures the first time required for the developer to be transferred from the replenishment port to the position where the sensor is provided, and the first time And predicting a second time required for the developer to be transferred from the position where the sensor is disposed to the replenishment port through the consuming portion,
In the second mode for forming an image, the control unit causes the replenishment unit to start operation after a delay time corresponding to the second time from the time when the detection result of the sensor indicates the decrease of the toner concentration. An image forming apparatus for controlling the supply unit. The image according to claim 1, wherein the control unit executes the measurement for the first time period in a state where the detection result of the sensor indicates that the toner concentration of the developer in the container is uniform. Forming equipment. The control unit controls the replenishment unit to replenish toner for checking from the replenishment port, and then measures the time until the toner concentration detected by the sensor reaches a maximum value as the first time. The image forming apparatus according to claim 2. After receiving an instruction to form an image, the control unit executes the operation in the first mode for checking the state of the developing unit before starting the execution of image formation in the second mode. The image forming apparatus according to any one of claims 1 to 3.

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