Patent Grant
10551785
The entire disclosure of Japanese patent Application No. 2018-020551, filed on Feb. 7, 2018, is incorporated herein by reference in its entirety.
The present invention relates to an image forming apparatus and an image forming apparatus control program. More specifically, the present invention relates to an image forming apparatus provided with a photoreceptor to which a lubricant is applied and an image forming apparatus control program.
Electrophotographic image forming apparatuses include, for example, facsimile machines, copiers, printers, multi function peripherals (MFPs) having a scanner function, a facsimile function, a copy function, a function as a printer, a data communication function, and a server function, and the like.
In general, an electrophotographic image forming apparatus develops an electrostatic latent image formed on an image carrier by using a developing device to form a toner image and transfers the toner image to a sheet. Then, the apparatus forms an image on the sheet by fixing the toner image on the sheet with a fixer. In addition, some image forming apparatuses develop an electrostatic latent image on the surface of a photoreceptor by using a developing device to form a toner image, transfer the toner image to an intermediate transfer belt by using a primary transfer roller, and secondarily transfer the toner image on the intermediate transfer belt to a sheet by using a secondary transfer roller. In this case, the photoreceptor and the intermediate transfer belt serve as image carriers.
Known for cleaning performance and toner releasability improvement is an image forming apparatus in which a lubricant such as zinc stearate is applied to an image carrier. In a case where an extra lubricant is applied to the image carrier in this type of image forming apparatus, the magnetic brush of the toner that is formed on the peripheral surface of a developing roller of a developing device may abut against the image carrier, bonding may occur between the lubricant and the toner, and the lubricant may be recovered in the developing device. Once the lubricant is recovered in the developing device, an image forming operation that is performed by the image forming apparatus may be adversely affected.
The related art provides techniques for preventing lubricant mixing into a developing device and for removing a lubricant mixed in a developing device. Disclosed in JP 2014-211471 A is an image forming apparatus provided with a lubricant recoverer facing a developing roller and recovering a lubricant on the developing roller. In addition, disclosed in JP 2016-212175 A is an image forming apparatus provided with a lubricant remover disposed on the downstream side of a cleaner and the upstream side of a developer in the rotational direction of a photoreceptor and removing a lubricant adhering to the surface of the photoreceptor.
However, in the related art, it is unknown why lubricant mixing into the developing device adversely affects an image forming operation of the image forming apparatus. For this reason, it has been impossible to effectively deter adverse effects on image forming operations of image forming apparatuses.
The present invention is intended to solve the above problems, and an object of the present invention is to provide an image forming apparatus and an image forming apparatus control program with which an adverse effect on an image forming operation can be effectively deterred.
To achieve the abovementioned object, according to an aspect of the present invention, an image forming apparatus reflecting one aspect of the present invention comprises: an image carrier to which a lubricant is applied; a developing device that develops an electrostatic latent image carried on the image carrier with toner, and includes a casing accommodating a toner-containing developer and a developing sleeve supplying the image carrier with the toner contained in the developer accommodated in the casing; and a hardware processor that detects information indicating a state of lubricant adhesion to the developing sleeve, and performs, based on a result of the detection by the hardware processor, a lubricant removing operation as an operation for removing the lubricant adhering to the developing sleeve.
The advantages and features provided by one or more embodiments of the invention will become more fully understood from the detailed description given hereinbelow and the appended drawings which are given by way of illustration only, and thus are not intended as a definition of the limits of the present invention:
Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the disclosed embodiments.
In the following embodiment, a case where an image forming apparatus is an MFP will be described. The image forming apparatus may also be a facsimile machine, a copier, a printer, or the like instead of the MFP.
[Configuration of Image Forming Apparatus]
The configuration of an image forming apparatus 1 according to the present embodiment will be described first.
Referring to
The toner image former 2 synthesizes images having the four colors of yellow (Y), magenta (M), cyan (C), and black (K) in a so-called tandem manner to form a toner image on a sheet. The toner image former 2 includes image forming units 21Y, 21M, 21C, and 21K (hereinafter, any one of the image forming units will be referred to as an image forming unit 21 in some cases) for the colors of Y, M, C, and K, respectively, an intermediate transfer belt 22, a primary transfer roller 23 for each of the colors of Y, M, C, and K, and a secondary transfer roller 24.
The image forming unit 21 for each of the colors of Y, M, C, and K includes, for example, a photoreceptor 25 (an example of an image carrier), a charging device 26, an exposure device 27, a developing device 28, and a cleaning device 29. The photoreceptor 25 is rotationally driven in the direction that is indicated by an arrow α in
The intermediate transfer belt 22 is provided on the left side of the image forming unit 21 for each of the colors of Y, M, C, and K. The intermediate transfer belt 22 is annular and is laid across a plurality of rotating rollers 22a. The intermediate transfer belt 22 is rotationally driven in the direction that is indicated by an arrow β in
The fixing device 3 fixes the toner image on the sheet by transporting the toner image-carrying sheet along the transport route TR while gripping the sheet.
The image forming apparatus 1 charges the surface of the photoreceptor 25 with the charging device 26 by rotating the photoreceptor 25. The image forming apparatus 1 forms an electrostatic latent image on the surface of the photoreceptor 25 by performing exposure in accordance with image formation information with the exposure device 27 with respect to the charged surface of the photoreceptor 25. A lubricant is applied to the surface of the photoreceptor 25.
Next, the image forming apparatus 1 forms the toner image on the surface of the photoreceptor 25 by supplying toner from the developing device 28 with respect to the electrostatic latent image-formed photoreceptor 25 and performing development.
Next, the image forming apparatus 1 sequentially transfers the toner image formed on the photoreceptor 25 to the surface of the intermediate transfer belt 22 by using the primary transfer roller 23 (primary transfer). In the case of a full color image, a toner image in which toner images respectively having the colors of Y, M, C, and K are synthesized is formed on the surface of the intermediate transfer belt 22.
The image forming apparatus 1 removes, with the cleaning device 29, the toner that remains on the photoreceptor 25 without being transferred to the intermediate transfer belt 22.
Subsequently, the image forming apparatus 1 transports the toner image formed on the surface of the intermediate transfer belt 22 to a position facing the secondary transfer roller 24 with the rotating roller 22a.
The image forming apparatus 1 feeds a sheet M and guides the sheet M between the intermediate transfer belt 22 and the secondary transfer roller 24 along the transport route TR with a plurality of transport rollers (not illustrated). Then, the image forming apparatus 1 transfers the toner image formed on the surface of the intermediate transfer belt 22 to the sheet M with the secondary transfer roller 24.
The image forming apparatus 1 guides the toner image-transferred sheet M to the fixing device 3 and fixes the toner image on the sheet M with the fixing device 3. Subsequently, the image forming apparatus 1 discharges the toner image-fixed sheet M to the outside of the image forming apparatus 1.
The image forming apparatus 1 further includes a controller 4 (an example of a remover, a bias detector, a determiner, a reference value decider, and a printing rate detector), an environment sensor 51 (an example of an acquirer), and a concentration detector 52.
The controller 4 includes, for example, a central processing unit (CPU) 4a controlling the entire image forming apparatus 1 in accordance with a control program, a ROM 4b storing the control program, a random access memory (RAM) 4c constituting a work area of the CPU 4a, and a hard disk drive (HDD) 4d storing various types of information.
The environment sensor 51 detects information indicating the environment of the image forming apparatus 1 and outputs the information (here, the information is the temperature and the humidity around the image forming apparatus 1) to the controller 4.
The concentration detector 52 detects the concentration of the toner image formed on the intermediate transfer belt 22 in image stabilization processing (described later) and outputs the concentration to the controller 4.
Referring to
The housing 31 accommodates a developer containing toner and a carrier. The partition wall 32 is provided inside the housing 31. The partition wall 32 partitions the inside of the housing 31 into a stirring tank 31a and a supply tank 31b. Both the stirring tank 31a and the supply tank 31b extend along a rotation axis R of a developing sleeve 33a.
The developing roller 33 has a cylindrical shape and faces the photoreceptor 25 at a required interval. The developing roller 33 is supported by the housing 31. The developing roller 33 includes the developing sleeve 33a and a magnet member 33b. The developing sleeve 33a supplies the photoreceptor 25 with the toner contained in the developer accommodated in the housing 31. The developing sleeve 33a has a cylindrical shape and rotates around the rotation axis R in the direction that is indicated by an arrow AR1. The magnet member 33b has a cylindrical shape, and the outer peripheral surface of the magnet member 33b is alternately magnetized to the north and south poles along the circumferential direction. The developing roller 33 acquires the developer from the inside of the supply tank 31b and guides the acquired developer to a developing region RG facing the photoreceptor 25 with the developing sleeve 33a while holding the acquired developer on the outer peripheral surface of the developing sleeve 33a with the magnetic force of the magnet member 33b.
The regulating member 36 has a plate shape and continuously extends in parallel to the rotation axis R. The regulating member 36 is fixed to the housing 31. The end part of the regulating member 36 that is on the side which is close to the developing roller 33 (end part in a direction perpendicular to the rotation axis R) faces the S pole of the magnet member 33b and is spaced apart from the outer peripheral surface of the rotating developing sleeve 33a. The regulating member 36 regulates the amount of the toner that is supplied to the photoreceptor 25 (amount of the developer that is transported to the developing region RG) by regulating the region through which the developer held on the outer peripheral surface of the developing sleeve 33a passes to the space between the end part and the outer peripheral surface.
The cleaning device 29 includes a cleaning blade 41, a lubricant 42, and an applicator 43. The cleaning blade 41 is in contact with the photoreceptor 25 and recovers the toner that remains on the photoreceptor 25 after the primary transfer. The lubricant 42 is made of zinc stearate or the like. The lubricant 42 is pressed against the applicator 43 by an elastic body such as a spring. The applicator 43 is provided so as to face the photoreceptor 25 on the upstream side of the developing region RG in the rotational direction of the photoreceptor 25. The applicator 43 is made of a brush roller or the like and rotates in the direction that is indicated by an arrow AR4. As a result, the applicator 43 scrapes the surface of the lubricant 42 and applies the lubricant 42 to the photoreceptor 25.
The image forming apparatus 1 further includes a motor 53, an ammeter 54 (an example of a torque detector), and an optical sensor 55 (an example of a glossiness detector). The motor 53 rotationally drives the developing sleeve 33a. The ammeter 54 measures the current value that flows to the motor 53 when the developing sleeve 33a is driven. The optical sensor 55 irradiates the developing sleeve 33a with light and outputs a voltage value corresponding to received reflected light to the controller 4.
[Reasons why Lubricant Mixing into Developing Device Adversely Affects Image Forming Operation]
The inventor of the present application found that lubricant mixing into a developing device adversely affects an image forming operation of an image forming apparatus because of the following reasons.
Referring to
Referring to
Referring to
The amount by which the lubricant LB adheres to the developing sleeve 33a and the developer transport amount of the developing sleeve 33a are inversely proportional to each other. When the amount by which the lubricant LB adheres onto the developing sleeve 33a increases with an increase in the period of use of the developing roller 33, the developer transport amount of the developing sleeve 33a falls below the lower limit value of an allowable range, and then the image forming operation is adversely affected.
Referring to
In a case where a lubricant adheres to the developing sleeve 33a illustrated in
In this regard, the controller 4 detects information indicating the state of lubricant adhesion to the developing sleeve 33a and performs a lubricant removing operation based on the result of the detection at any timing as an operation for removing the lubricant adhering on the developing sleeve 33a.
[Method for Detecting State of Lubricant Adhesion to Developing Sleeve]
Described below are first to fourth detection methods for detecting the information indicating the state of lubricant adhesion to the developing sleeve 33a (adhesion amount in the present embodiment). In the first to fourth detection methods, the necessity of the lubricant removing operation is determined based on a detected value and a reference value. It should be noted that the following first to fourth detection methods can be adopted in appropriate combination. Methods for detecting the information indicating the state of lubricant adhesion to the developing sleeve 33a are not limited to the following first to fourth detection methods, and any method may be used.
(1) First Detection Method
Referring to
The developing bias of the image forming unit 21 for each color is decided in the image stabilization processing. In the case of deciding the developing bias of the image forming unit 21 for a certain color, the controller 4 applies different developing biases to the developing sleeve 33a by using the image forming unit 21 for that color and forms a plurality of patches (image having a predetermined pattern) PA on the intermediate transfer belt 22. The controller 4 optically detects the concentration of each of the plurality of patches PA with the concentration detector 52. The controller 4 decides the developing bias used to form a patch PA1, which is a target concentration, as the value of the developing bias suitable for forming the image of that color.
Referring to
In this regard, the controller 4 detects the value of the developing bias decided as a result of the image stabilizing processing as the first detection method for detecting the information indicating the state of lubricant adhesion to the developing sleeve 33a.
In a case where the first detection method is adopted, the controller 4 sets an upper limit value TH1 of the developing bias at which the transport amount becomes the range Q and determines the necessity of the lubricant removing operation based on the detected developing bias value and the upper limit value TH1. In a case where the detected developing bias value exceeds the upper limit value TH1, the controller 4 determines that the amount of lubricant adhesion to the developing sleeve 33a has reached the upper limit value and performs the lubricant removing operation.
The relationship between the detected developing bias value and the developer transport amount of the developing sleeve 33a varies with the operation environment of the image forming apparatus 1 (temperature and humidity around the image forming apparatus 1). Specifically, in a case where the environment is a high-temperature and high-humidity environment, the value of the developing bias with respect to the transport amount increases and the relationship between the detected developing bias value and the developer transport amount of the developing sleeve 33a becomes the relationship that is indicated by a line LN2. In a case where the environment is a low-temperature and low-humidity environment, the value of the developing bias with respect to the transport amount decreases and the relationship between the detected developing bias value and the developer transport amount of the developing sleeve 33a becomes the relationship that is indicated by a line LN3.
In this regard, the controller 4 may acquire the environment-indicating information (temperature and humidity around the image forming apparatus 1) from the environment sensor 51 and set the upper limit value of the developing bias at which the transport amount becomes the range Q based on the acquired information. Specifically, in a case where the environment is a high-temperature and high-humidity environment, the upper limit value of the developing bias at which the transport amount becomes the range Q is set to an upper limit value TH2 by means of the line LN2. In a case where the environment is a low-temperature and low-humidity environment, the upper limit value of the developing bias at which the transport amount becomes the range Q is set to an upper limit value TH3 by means of the line LN3. As a result, it is possible to more accurately obtain the state of lubricant adhesion to the developing sleeve 33a.
In a case where the first detection method is adopted, the lines LN1, LN2, and LN3 are pre-calculated by experiment or the like and stored in the HDD 4d or the like.
In the first detection method, the controller 4 may detect the developing bias actually applied to the developing sleeve 33a instead of the value of the developing bias decided as a result of the image stabilizing processing.
(2) Second Detection Method
Referring to
In this regard, the controller 4 detects a developing torque-indicating value as the second detection method for detecting the information indicating the state of lubricant adhesion to the developing sleeve 33a. Adopted here as the developing torque-indicating value is the current value measured by the ammeter 54 (current value flowing to the motor 53 when the developing sleeve 33a is driven).
In a case where the second detection method is adopted, the controller 4 sets a lower limit value TH11 of the developing torque at which the transport amount becomes the range Q based on the line LN11 and determines the necessity of the lubricant removing operation based on the detected developing torque value and the lower limit value TH11. In a case where the detected developing torque value is exceeded by the lower limit value TH11, the controller 4 determines that the amount of lubricant adhesion to the developing sleeve 33a has reached the upper limit value and performs the lubricant removing operation.
The relationship between the developing torque value and the developer transport amount of the developing sleeve 33a varies with the operation environment of the image forming apparatus 1 (temperature and humidity around the image forming apparatus 1). Specifically, in a case where the environment is a high-temperature and high-humidity environment, the value of the developing torque with respect to the transport amount decreases and the relationship between the detected developing torque value and the developer transport amount of the developing sleeve 33a becomes the relationship that is indicated by a line LN12. In a case where the environment is a low-temperature and low-humidity environment, the value of the developing torque with respect to the transport amount increases and the relationship between the detected developing torque value and the developer transport amount of the developing sleeve 33a becomes the relationship that is indicated by a line LN13.
In this regard, the controller 4 may acquire the information indicating the environment of the image forming apparatus 1 (temperature and humidity around the image forming apparatus 1) from the environment sensor 51 and set the lower limit value of the developing torque at which the transport amount becomes the range Q based on the acquired information. Specifically, in a case where the environment is a high-temperature and high-humidity environment, the lower limit value of the developing torque at which the transport amount becomes the range Q is set to a lower limit value TH12 by means of the line LN12. In a case where the environment is a low-temperature and low-humidity environment, the lower limit value of the developing torque at which the transport amount becomes the range Q is set to a lower limit value TH13 by means of the line LN13. As a result, it is possible to more accurately obtain the state of lubricant adhesion to the developing sleeve 33a.
In a case where the second detection method is adopted, the lines LN11, LN12, and LN13 are pre-calculated by experiment or the like and stored in the HDD 4d or the like.
(3) Third Detection Method
Referring to
In this regard, the controller 4 detects the glossiness of the surface of the developing sleeve 33a based on the voltage value output from the optical sensor 55 as the third detection method for detecting the information indicating the state of lubricant adhesion to the developing sleeve 33a.
In a case where the third detection method is adopted, the controller 4 sets a lower limit value TH21 of the glossiness at which the transport amount becomes the range Q based on the line LN21 and determines the necessity of the lubricant removing operation based on the detected glossiness and the lower limit value TH21. In a case where the detected glossiness is exceeded by the lower limit value TH21, the controller 4 determines that the amount of lubricant adhesion to the developing sleeve 33a has reached the upper limit value and performs the lubricant removing operation.
In a case where the third detection method is adopted, the line LN21 is pre-calculated by experiment or the like and stored in the HDD 4d or the like.
(4) Fourth Detection Method
Referring to
In this regard, the controller 4 calculates and stores the printing rate of a printed image every time printing is performed and detects the average printing rate of the image that the image forming apparatus 1 printed in the past as the fourth detection method for detecting the information indicating the state of lubricant adhesion to the developing sleeve 33a.
In a case where the fourth detection method is adopted, the controller 4 sets a lower limit value TH31 of the average printing rate at which the transport amount becomes the range Q based on the line LN31 and determines the necessity of the lubricant removing operation based on the detected average printing rate and the lower limit value TH31. In a case where the detected average printing rate is exceeded by the lower limit value TH31, the controller 4 determines that the amount of lubricant adhesion to the developing sleeve 33a has reached the upper limit value and performs the lubricant removing operation.
[Lubricant Removing Operation Performed by Image Forming Apparatus]
Described below is the lubricant removing operation (first and second lubricant removing operations) performed by the image forming apparatus 1. The following first and second lubricant removing operations can be adopted in combination. In addition, the first and second lubricant removing operations may be selectively used in accordance with the amount of lubricant adhesion to the developing sleeve 33a. The lubricant removing operation performed by the image forming apparatus 1 is not limited to the following first and second lubricant removing operations and may be any operation.
(1) First Lubricant Removing Operation
Referring to
Although any image can be adopted as the removal image, it is preferable that the printing rate of the removal image in the sheet transport direction has a value that is at least as high as a predetermined value (such as 20%) over the entire printing region in the direction perpendicular to the sheet transport direction. The printing rate in the sheet transport direction is the ratio of the total length of a length L1 of the printed part to a length L in the sheet transport direction.
Referring to
Referring to
Referring to
Referring to
(2) Second Lubricant Removing Operation
Referring to
The controller 4 switches the lubricant removing member 56 from the separated state to the contact state and rotates the lubricant removing member 56 as the second lubricant removing operation. As a result, the lubricant adhering to the developing sleeve 33a is scraped and recovered by the rotating lubricant removing member 56.
[Flowchart]
A flowchart illustrating the operation of the image forming apparatus 1 will be described below.
Referring to
In a case where it is determined in step S9 that the detected amount of lubricant adhesion deviates from the upper limit or the lower limit of the adhesion amount (YES in S9), the controller 4 shifts to a lubricant removing mode and performs the lubricant removing operation (S11). Next, the controller 4 shifts to the next printing process (S13) and terminates the processing.
In a case where it is determined in step S9 that the detected amount of lubricant adhesion does not deviate from the upper limit or the lower limit of the adhesion amount (NO in S9), the controller 4 shifts to the next printing process without performing the lubricant removing operation (S13) and terminates the processing.
According to the above embodiment, the information that indicates the state of lubricant adhesion to the developing sleeve 33a is detected and the lubricant removing operation is performed based on the result of the detection, and thus an adverse effect on the image forming operation of the image forming apparatus 1 can be effectively deterred.
[Others]
The processing according to the above-described embodiment may be performed by means of software or may be performed by means of a hardware circuit. It is also possible to provide a program for executing the processing according to the above-described embodiment, and a user may be provided with the program recorded on a recording medium such as a CD-ROM, a flexible disk, a hard disk, a ROM, a RAM, and a memory card. The program is executed by a computer such as a CPU. In addition, the program may be downloaded to the apparatus via a communication line such as the Internet.
Although embodiments of the present invention have been described and illustrated in detail, the disclosed embodiments are made for purposes of illustration and example only and not limitation. The scope of the present invention should be interpreted by terms of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-020551 | Feb 2018 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20100239969 | Owada | Sep 2010 | A1 |
| 20150261129 | Hayashi | Sep 2015 | A1 |
| 20160320742 | Ishida et al. | Nov 2016 | A1 |
| 20170038720 | Hirai | Feb 2017 | A1 |
| 20180299810 | Miura | Oct 2018 | A1 |
| 20190101844 | Mochizuki | Apr 2019 | A1 |
| Number | Date | Country |
|---|---|---|
| 2014211471 | Nov 2014 | JP |
| 2016212175 | Dec 2016 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20190243298 A1 | Aug 2019 | US |
