JP7409094B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus.

2. Description of the Related Art Techniques related to contact and separation operations for bringing a cleaning roller into contact with or away from a fixing member or a pressure member have been considered and are already known.
For example, in Patent Document 1, even in a film-type image heating device equipped with a cleaning roller, when fixing the first sheet during continuous fixing, the A configuration is disclosed in which the cleaning roller is separated from the pressure roller and comes into contact with the pressure roller from the second sheet onwards.

However, in the conventional contact/separation operation of the cleaning roller, if the cleaning roller is brought into contact only while paper is passing, repeating rotation and stopping (non-rotation) may result in mechanical loads on the parts of the mechanism that performs the contact/separation of the cleaning roller. There was a problem in that this increased the wear and tear and accelerated wear and deterioration. Further, in the conventional contact/separation operation of the cleaning roller, when changing the temperature of the fixing member, there is a problem that there is a delay in the temperature change of the fixing member due to the cleaning roller being in contact with the fixing member.
SUMMARY OF THE INVENTION An object of the present invention is to improve the contact/separation operation of a cleaning member.

In order to solve the above-mentioned problems, the present invention includes at least a fixing member, a heat source that heats the fixing member, and a pressure member that forms a nip portion between the fixing member and the fixing member. An image forming apparatus comprising a fixing device that conveys a recording medium carrying an unfixed toner image to the recording medium and fixes the unfixed toner image to the recording medium,
a cleaning member that is provided so as to be able to come into contact with and separate from either the pressure member or the fixing member, and cleans the surface of either the pressure member or the fixation member;
a mechanism for moving the cleaning member toward and away from each other;
The image forming apparatus has a paper feeding mode in which the recording medium is repeatedly conveyed and stopped between feeding the recording medium and discharging the recording medium,
The contact/separation mechanism is characterized in that, in the paper passing mode, the cleaning member is separated from either the pressure member or the fixing member.

According to the present invention, it is possible to improve the contact/separation operation of the cleaning member.

FIG. 2 is a schematic diagram illustrating main parts of a fixing device included in an image forming apparatus according to an embodiment. FIG. 2 is a block diagram illustrating a function of a control unit controlling a contact/separation mechanism according to an embodiment. FIG. 3 is a schematic diagram illustrating how collected toner is stacked on a cleaning member. FIG. 7 is a schematic diagram illustrating a problem that occurs when a cleaning member on which toner is stacked comes into contact with the pressing member while the pressure member is stopped. 7 is a graph showing an example of temperature change when the cleaning member is in contact with the pressure member and when the cleaning member is separated from the pressure member when lowering the fixing target temperature. 7 is a graph showing an example of temperature change when the cleaning member is brought into contact with the pressure member and when the cleaning member is separated from the pressure member during the start-up operation of the image forming apparatus.

An image forming apparatus according to the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the embodiments shown below, and may be modified within the scope of those skilled in the art, such as other embodiments, additions, modifications, deletions, etc. These are also included within the scope of the present invention as long as they exhibit the functions and effects of the present invention. Further, in each drawing, components and corresponding parts having the same configuration or function are denoted by the same reference numerals, and the explanation thereof will be omitted.
An image forming apparatus according to an embodiment includes an electrostatic latent image forming device that forms an electrostatic latent image on a latent image carrier, a developing device that develops the electrostatic latent image to form a toner image, and a developing device that records the toner image. It has a transfer device that transfers the image onto a medium, a fixing device that fixes the transferred image transferred to the recording medium, and further includes other devices that are appropriately selected as necessary.

The present invention has the following features regarding adjusting the period during which the cleaning member contacts the pressure member or the fixing member during the contact/separation operation of the cleaning member of the fixing device.
First, if it is known in advance that the cleaning member will repeat rotating/stopping during paper passing (paper passing mode), the cleaning member is separated from the pressure member or the fixing member.
Second, when changing the temperature of the fixing device, the cleaning member is separated from the pressure member or the fixing member. The temperature of the fixing device is changed (adjusted) when the fixing control target temperature is switched to a lower value, or when the image forming apparatus is being started up.
The features of the present invention described above will be explained in detail using the drawings.

First, a fixing device included in an image forming apparatus to which the present invention is applied will be described.
FIG. 1 is a schematic diagram illustrating main parts of a fixing device included in an image forming apparatus according to an embodiment. The fixing device includes a fixing member 11 (also referred to as a "fixing roller"), a pressure member (also referred to as a "pressure roller") 21, a cleaning member (also referred to as a "cleaning roller") 31, and temperature sensors 41a and 41b. , 42. The fixing member 11 has a heat source 12 inside. In the configuration example of FIG. 1, a conveying means for conveying the recording medium to the nip portion N and the like are omitted.

The fixing device forms a nip portion N between the fixing member 11 and the pressure member 21. The image forming apparatus conveys the recording medium 50 carrying the unfixed toner image 51 in the nip portion N to the fixing device, and the fixing device fixes the unfixed toner image 51 to the recording medium 50.

The cleaning member 31 is provided so as to be able to come into contact with and separate from the pressure member 21, and cleans the surface of the pressure member 21.

The temperature sensor 41a detects the surface temperature of the cleaning member 31.
The temperature sensor 41b detects the surface temperature of the pressure member 21.
Temperature sensor 42 detects the surface temperature of fixing member 11 .
The fixing device does not need to include temperature sensors 41a and 41b.
In the following description, when a plurality of temperature sensors are not distinguished, they will be appropriately referred to as "temperature sensor 40."

The image forming apparatus also includes a contact/separation mechanism (also referred to as a "contact/separation mechanism") (not shown in FIG. 1) that brings the cleaning member 31 into contact with or separates from the pressure member 21. (not available). The contact/separation mechanism is composed of, for example, a cam.
The drive of the contact/separation mechanism is controlled by, for example, a control section as a control means included in the image forming apparatus.

The control unit controls the entire image forming apparatus. Further, the control section controls image forming operations in each section of the image forming apparatus, such as a latent image forming device, a developing device, a transfer device, a fixing device, a recording medium transport device, and other appropriately selected devices.
FIG. 2 is a block diagram illustrating the function of the control unit of one embodiment to control the contact/separation mechanism. In FIG. 2, the control unit 110, memory 120, operation unit 130, I/F unit 140, and contact/separation mechanism 150 are shown, and other parts are omitted.

The control unit 110 includes, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and the like.
The CPU executes various programs and controls the entire image processing apparatus based on arithmetic processing and control programs.
RAM is a volatile storage medium for reading and writing information at high speed, and functions as a work area when the CPU executes a program.
ROM is a read-only nonvolatile storage medium that stores various programs and control programs.
Hereinafter, one or both of RAM and ROM will also be referred to as "system memory."

The memory 120 is a storage unit that temporarily or permanently stores data under the control of the image forming apparatus.
The operation unit 130 is a means operated by a user to perform operations and commands such as printing and scanning images. For example, an operation panel may be used as the operation unit 130.
The I/F unit 140 is an interface that has terminals that can communicate with the outside, such as a USB (Universal Serial Bus), a LAN (Local Area Network), and WiFi, and that transmits and receives data.

The contact/separation mechanism 150 causes the cleaning member 31 to come into contact with the pressure member 21 or to separate it from the pressure member 21 . The contact/separation mechanism 150 causes the cleaning member 31 to contact and separate from the pressure member under the control of the control unit 110 .

The control unit 110 detects a predetermined condition described in each embodiment below, and controls the contact/separation mechanism 150 to separate the cleaning member 31 from the pressure member 21 based on the detected predetermined condition. The predetermined conditions may be stored in advance in the memory 120, system memory, or the like. The predetermined conditions may be received from the outside via the I/F unit 140 and stored in the memory 120, system memory, or the like, for example.
Each embodiment will be described below.

Embodiment 1.
In this embodiment, an aspect will be described in which the contact and separation mechanism 150 separates the cleaning member 31 from the pressure member 21 when it is known in advance that the operation is an operation of repeating rotation/stopping during paper passing (paper passing mode). do.

First, a problem that occurs when toner is piled up on the cleaning member 31 will be explained.
FIG. 3 is a schematic diagram illustrating how the collected toner is stacked on the cleaning member. FIG. 4 is a schematic diagram illustrating a problem that occurs when a cleaning member on which toner is stacked comes into contact with the pressure member while the pressure member is stopped.
In the image forming apparatus, when the cleaning member 31 collects the toner that has adhered to the pressure member 21 over time, the toner collected on the cleaning member 31 changes over time from the left side of the arrow to the right side of the arrow in FIG. They are laminated to form a toner layer 52 on the surface.

The cleaning member 31 generally rotates/stops in response to the rotation/stop of the pressure member 21. For example, when the pressure member 21 repeatedly rotates and stops from paper feeding to paper ejection, if the cleaning member 31 is brought into contact with the pressure member 21 while it is stopped, the nip portion may be damaged as shown in FIG. The toner (in the contact area) is melted and plastically deformed, resulting in a flat portion 53. If such a flat portion 53 is formed, the cleaning member 31 may not rotate properly. Therefore, it is necessary to separate them while the rotation is stopped.

On the other hand, in a printing operation, a sheet of paper may repeatedly rotate and stop from being fed to being ejected. For example, in Patent Document 2, in a cleaning mode in which a pressure member is cleaned with a cleaning sheet, a movement of repeatedly rotating and stopping is performed with a sheet between the fixing roller and the pressure roller. For example, when the technique disclosed in Patent Document 2 is applied to an image forming apparatus having a cleaning member 31, if the movement of contacting the cleaning member 31 during rotation and separating it while stopped is repeated, a sheet of paper may From paper feeding to paper ejection, contact/separation operations are performed several dozen times at most. For this reason, when the cleaning member 31 is brought into contact with and separated from the cleaning member 31 multiple times, a load is repeatedly applied to a mechanism such as a cam included in the contact and separation mechanism, which accelerates deterioration and shortens the service life. The load on the contact/separation mechanism is not limited to the cleaning mode, but is a problem that similarly occurs in operations that repeat rotation and stop.

Therefore, in the present invention, the cleaning member 31 is separated from the pressure member 21 not only in the above-mentioned cleaning mode but also in the paper passing mode in which repeated rotation and stop operations can be expected, so that the contact/separation mechanism is activated. Suppress deterioration. In this way, the fixing device included in the image forming apparatus can operate satisfactorily. For example, by reducing the number of operations of the contact/separation mechanism, it becomes possible to suppress deterioration of the cam, etc. included in the contact/separation mechanism, thereby reducing the frequency of replacing parts of the mechanism and reducing costs.

The contact/separation mechanism 150 separates the cleaning member 31 from the pressure member 21 in the above-described paper passing mode.
The paper passing mode may be stored in advance in the memory 120 or the system memory of the control unit 110. For example, the control unit 110 receives a mode selected by the user from the operation unit 130, and if the mode selected by the user matches a pre-stored paper passing mode, the contact/separation mechanism 150 moves the cleaning member 31. Control may be performed so as to perform an operation of separating the pressure member 21 from the pressure member 21.

According to this embodiment, wear of the contact/separation mechanism components of the cleaning member can be suppressed.

Embodiment 2.
In this embodiment, as a case where the temperature of the fixing device is changed, a mode will be described in which the contact/separation mechanism 150 separates the cleaning member 31 from the pressure member 21 when the fixing control target temperature switches to a lowering direction.
In controlling the fixing temperature, if the cleaning member 31 is in contact with the pressure member 21 when the target temperature changes from a high state to a low state, the pressure member 21 will be removed from the cleaning member 31 which is heated and has accumulated heat. Since heat is supplied to the fixing member 21, the temperature of the fixing member 11 cannot be lowered quickly.

FIG. 5 shows an example of temperature change when the cleaning member 31 is brought into contact with the pressure member 21 and when it is separated from the pressure member 21 when lowering the fixing target temperature. In the graph, the broken line shows the target temperature, the solid line shows the temperature change when the cleaning member 31 is separated, and the one-dot broken line shows the temperature change when the cleaning member 31 comes into contact.

In this embodiment, when the target fixing temperature is switched to decrease due to a change in the fixing operation state, the contact/separation mechanism 150 separates the cleaning member 31 from the pressure member 21 . For example, the control unit 110 may control the operation of the contact/separation mechanism 150 when detecting a change in the fixing operation state and performing control to lower the fixing target temperature.
In this way, the temperature of the pressure member 21 can be quickly lowered, and the temperature of the fixing member 11 that is in contact with the pressure member 21 can be lowered quickly.
According to this embodiment, it is possible to suppress the delay in temperature reduction of the fixing member due to the heat capacity of the cleaning member.

Embodiment 3.
In this embodiment, as a case where the temperature of the fixing device is changed, a mode will be described in which the contact/separation mechanism 150 separates the cleaning member 31 from the pressure member 21 during the startup operation of the image forming apparatus.
In fixing temperature control, if the cleaning member 31 is brought into contact with the pressure member 21 during the start-up operation, the heating rate of the fixing member 11 in contact with the pressure member 21 will be reduced due to the heat capacity of the cleaning member 31. This also slows down the process and increases the warm-up time.

FIG. 6 shows an example of temperature change when the cleaning member 31 is brought into contact with the pressure member 21 and when it is separated from the pressure member 21 during the start-up operation of the image forming apparatus. In the graph, the broken line shows the target temperature, the solid line shows the temperature change when the cleaning member 31 is separated, and the one-dot broken line shows the temperature change when the cleaning member 31 comes into contact.

In this embodiment, the contact/separation mechanism 150 separates the cleaning member 31 from the pressure member 21 during the rising operation. For example, the control unit 110 may control the operation of the contact/separation mechanism 150 when detecting startup of the image forming apparatus and performing the startup operation.
In this way, the warm-up time can be shortened.

Here, the start-up operation refers to a return from a sleep state, a return from an abnormal state such as a jam or an open cover, or an operation until printing becomes possible after the power is turned on. In other words, focusing on the fixing temperature, it refers to the operation of increasing the fixing temperature from a low fixing temperature until it recovers to a desired fixing temperature that allows printing.

According to the present embodiment, in the operation of increasing the temperature of the fixing member, it is possible to suppress a delay in increasing the temperature of the fixing member due to the heat capacity of the cleaning roller.

Other embodiments.
Each of the embodiments described above can also be implemented by combining one or more embodiments.

Further, in each of the embodiments described above, the cleaning member 31 is provided so as to be able to come into contact with and separate from the pressure member 21, but the present invention is not limited to this. The cleaning member 31 may be provided so as to be able to approach and separate from the fixing member 11. However, when a cleaning member is provided on the fixing member, it is advantageous in that the fixing member can be directly cleaned, but when the cleaning member is placed in contact with the fixing member, the heat capacity of the cleaning member directly affects the fixing member, resulting in Temperature variations tend to occur, so if you are concerned about temperature variations, it is better to install it on the pressure roller side. Further, the image forming apparatus may include a plurality of cleaning members 31, and the cleaning member 31 may be provided for each of the fixing member 11 and the pressure member 21. When the cleaning member 31 comes into contact with and separates from the fixing member 11, the same operation is performed when the cleaning member 31 comes into contact with and separates from the pressure member 21.

11 Fixing member 12 Heat source 21 Pressure member 31 Cleaning member 40, 41a, 41b, 42 Temperature sensor 110 Control section 120 Memory 130 Operation section 140 I/F section 150 Contact/separation mechanism

Japanese Patent Application Publication No. 6-175520 Japanese Patent Application Publication No. 5-158375

Claims (5)

The recording medium includes at least a fixing member, a heat source that heats the fixing member, and a pressure member that forms a nip portion between the fixing member and the recording medium carrying an unfixed toner image in the nip portion. , an image forming apparatus including a fixing device for fixing an unfixed toner image to the recording medium,
a cleaning member that is provided so as to be able to come into contact with and separate from either the pressure member or the fixing member, and cleans the surface of either the pressure member or the fixation member;
a mechanism for moving the cleaning member toward and away from each other;
The image forming apparatus has a paper feeding mode in which the recording medium is repeatedly conveyed and stopped between feeding the recording medium and discharging the recording medium,
The image forming apparatus is characterized in that the contact/separation mechanism separates the cleaning member from either the pressure member or the fixing member in the paper passing mode. 2. The contact/separation mechanism is configured to separate the cleaning member from either the pressure member or the fixing member when the heat source stops heating the fixing member. 1. The image forming apparatus according to 1 . 3. The apparatus according to claim 1, wherein the contact/separation mechanism separates the cleaning member from either the pressure member or the fixing member during a start-up operation of the fixing device. The image forming apparatus described above. Claims 1 to 3, wherein the contact/separation mechanism separates the cleaning member from either the pressure member or the fixing member when the fixing device lowers the fixing temperature. The image forming apparatus according to any one of the above. 5. The apparatus according to claim 1, wherein the contact/separation mechanism separates the cleaning member from either the pressure member or the fixing member when increasing the temperature of the fixing device . The image forming apparatus according to any one of the items.

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