JP7195877B2 - Fixing member and heat fixing device - Google Patents

Description

The present invention relates to image forming apparatuses such as copiers, printers, facsimiles, and multifunction devices thereof.

2. Description of the Related Art A so-called heat roller type fixing device has been widely used in an image heating device (hereinafter referred to as a fixing device) provided in an image forming apparatus employing an electrophotographic method, an electrostatic recording method, or the like. In a heat roller type fixing device, a recording material bearing an unfixed toner image is passed through a nip portion formed by a fixing roller and a pressure roller that rotate while being pressed against each other, thereby forming a fixed image on the recording material. It is something that is established.

However, in recent years, from the perspective of promoting energy conservation, a film-heating type fixing device that heats via a fixing film (endless belt) with a small heat capacity, that is, a film fixing device, has been developed as an on-demand method with high heat transfer efficiency and quick start-up. A device has been proposed and put into practical use. In this film heating type fixing device, a seamless fixing belt is used in which a releasing layer such as fluororesin is laminated on the outer surface of a heat-resistant film such as polyimide.

In the above configuration, a pressure member such as a pressure pad is provided on the inner peripheral side of the endless belt, and the endless belt and the pressure roller (or the fixing roll) are pressed against the endless belt by the pressure member. A pressure roller (or a fixing roller) is brought into pressure contact. The unfixed toner on the recording medium is fixed on the recording medium by passing the recording medium through a pressurized area between the endless belt and the pressure roller (or fixing roll). Frictional resistance is kept low by interposing a lubricant such as fluorine-based or silicone-based heat-resistant grease or silicone oil between the endless belt and the pressure member, allowing the endless belt to rotate (movable) smoothly. becomes.

On the other hand, as the operation time of the fixing device elapses, deterioration of the lubricant over time, contamination of the inner sliding surface with foreign matter, abrasion of the inner surface of the belt, deterioration of the surface of the nip forming member and the inner surface of the belt, etc. occur, and the sliding load increases. gradually increases. If the sliding load of the fixing device continues to increase, image defects may occur, abnormal noise may occur due to sliding, and troubles such as belt breakage and gear breakage may occur.

Therefore, there is a demand for a mechanism that predicts the need for fixing device replacement and allows a service person to go to the fixing device for maintenance. Conventionally, in order to realize this mechanism, a method using counters for the number of sheets passed, the belt running distance, and the like has been mainly used.

However, with the diversification of device installation environments, frequency of use, types of paper used, etc. for each user, the factors that lead to the end of the life of the fixing device have come to be classified into various cases. If the number of sheets of paper and the distance traveled by the belt are determined only by counters, the belt is often replaced at an earlier stage than the appropriate replacement time.

Therefore, the following proposals have been made as means for predicting the life of the fixing device. Japanese Patent Application Laid-Open No. 2002-101000 includes current detection means for detecting current flowing through a drive means, and replacement timing determination means for determining replacement timing of a fixing device based on the detected current (sliding load, torque).

Japanese Patent Application Laid-Open No. 2001-005353

In the configuration of Patent Document 1, it is possible to determine when the fixing device needs to be replaced and to replace it, but it is not possible to know the cause of the increase in the sliding load. As a countermeasure, therefore, the fixing device has to be replaced, and parts in the fixing device that do not need to be replaced have to be replaced, leading to an increase in cost.

In order to solve the above problems, the invention according to claim 1 includes a heater, a fixing rotator heated by the heater, and a nip forming member that presses against the inner surface of the fixing rotator to form a nip portion. a pressure rotary body forming a nip portion together with a nip forming member via the fixing rotary body; and driving means for rotating at least one of the fixing rotary body and the pressure rotary body; To diagnose a factor of torque increase in a fixing device that pinches and conveys a recording material in a nip portion, heats and presses a recording material at the nip portion, and fixes the recording material, and is provided with torque information detection means for acquiring rotation torque information of the driving means. It is an image forming apparatus capable of

According to a second aspect of the present invention, the diagnosis means acquires torque under a plurality of temperature conditions, and judges whether or not a difference in the acquired torque information is equal to or greater than a predetermined value. The image forming apparatus according to .

According to the image forming apparatus of the present invention, it is possible to clarify the parts to be replaced in the fixing device by isolating the factors of the increase in the sliding load. leads to

1 is a schematic diagram for explaining an image forming apparatus of the present invention; FIG. 1 is a schematic cross-sectional view of a fixing device according to the present invention; FIG. 1 is a longitudinal schematic diagram of a fixing device in the present invention; FIG. It is a block diagram in the present invention. FIG. 5 is a diagram showing the temperature dependence of torque when sliding load increases. FIG. 3 is a diagram showing the temperature dependence of kinematic viscosity characteristics of a single base oil (oil). 3 is a diagram showing temperature dependence of sliding load (torque) in a fixing device; FIG. FIG. 4 is a diagram showing the temperature dependence of torque with and without lubricant. FIG. 10 is a diagram showing a time-series transition of torque when a rotational load increase occurs due to a film unit factor; FIG. 10 is a diagram showing a time-series transition of torque when a circumferential load increase occurs due to a pressure roller factor; FIG. 5 is a diagram for explaining a specific operation for a torque-up factor and a judgment flow; It is a figure which shows the example of a display displayed on a display apparatus. It is a figure which shows the factor which sliding load rises.

Hereinafter, embodiments of the present invention will be described based on the drawings.

[Image forming apparatus]
FIG. 1 is a sectional view of a printer 1, which is an image forming apparatus of this embodiment. The printer 1 is an image forming apparatus that transfers a toner image formed on a photosensitive drum 11 onto a recording material P in an image forming unit 10 and then fixes the image on the recording material P with a fixing device 40 .

As shown in FIG. 1, the printer 1 includes an image forming section (image forming station) 10 for forming toner images of Y (yellow), M (magenta), C (cyan), and Bk (black). there is The image forming unit 10 includes four photosensitive drums 11 (11Y, 11M, 11C, and 11Bk) corresponding to the colors Y, M, C, and Bk in order from the left side of FIG. direction.

A charger 12 , an exposure device 13 , a development device 14 , a primary transfer blade 17 and a cleaner 15 are arranged around each photosensitive drum 11 . The procedure for forming a Bk toner image will be described below, but the procedures for forming toner images of other colors are the same.

First, a procedure for forming a toner image on the recording material P will be described. After the surface of the photosensitive drum 11 is uniformly charged by the charger 12 , an electrostatic latent image is formed on the photosensitive drum 11 by exposure according to image information by the exposure device 13 . Then, the developing device 14 develops toner on the electrostatic latent image obtained by the exposing device 13 to form a toner image on the photosensitive drum 11 . At this time, similar steps are performed for other colors.

The toner image on each photosensitive drum 11 is primarily transferred onto the intermediate transfer belt 31 by the primary transfer blade 17 , and the toner remaining on the photosensitive drum 11 is removed by the cleaner 15 . Thus, the photosensitive drum 11 is ready for the next image formation.

On the other hand, the recording materials P placed on the feed cassette 20 or the multi-feed tray 25 are fed one by one to the registration roller pair 23 by a feeding mechanism (not shown). The pair of registration rollers 23 temporarily stop the recording material P, and if the recording material P is skewed with respect to the conveying direction, it straightens its direction, synchronizes with the toner image on the intermediate transfer belt 31, A recording material P is sent between the intermediate transfer belt 31 and the secondary transfer rollers 34 and 35 . A secondary transfer roller 35 transfers the toner image on the intermediate transfer belt 31 onto the recording material P. As shown in FIG.

The recording material P to which the toner image has been transferred is conveyed to the fixing device 40, and a fixed toner image is formed on the recording material P by heat and pressure processing.

Next, the fixing device 40 is described. FIG. 2 shows a sectional view of the fixing device 40, and FIG. 3 shows a front view of the fixing device 40. As shown in FIG. The film unit 60 that heats the image on the recording material P has a configuration in which the heater 600 that is in contact with the inner surface heats the flexible thin fixing film 603 . As shown in FIG. 2, the fixing film 603 has a nip portion N formed by pressure bonding between the heater 600 and the pressure roller 70, and nips and conveys the recording material P fed to the nip portion N. FIG. At this time, the heat generated by the heater 600 is applied to the recording material P through the fixing film 603, and the toner image T on the recording material P is fused and fixed to the recording material P. FIG.

The film unit 60 is a unit for applying heat and pressure to the image on the recording material P, is provided parallel to the pressure roller, and comprises a heater 600 , a heater holder 601 , a support stay 602 and a fixing film 603 .

The fixing film 603 is pressed toward the pressure roller 70 so that the nip portion N has a predetermined width. The heater 600 includes a substrate 610 and a resistance heating element 620 on the substrate 610 and is fixed to a recess on the bottom surface of the heater holder 601 . In this embodiment, the heating element 620 is provided on the back side of the substrate 610 (the side not in contact with the fixing film 603). ).

In order to reduce the rubbing load between the fixing film 603 and the heater 600, the surface of the substrate 610 is coated with a semi-solid lubricant (hereinafter referred to as grease) composed of a solid component (compound) and a base oil component (oil). , the slidability between the heater 600 and the fixing film 603 and between the heater holder 601 and the fixing film 603 is ensured. Grease compounds include solid lubricants such as graphite and molybdenum disulfide, metal oxides such as zinc oxide and silica, and fluorine resins such as polytetrafluoroethylene (PTFE). Examples of grease oil include heat-resistant polymer resin oils such as silicone oil and fluorosilicone oil. In this embodiment, PTFE powder particles (particle size: 3 μm) are used as the compound, and grease using fluorosilicone oil is used as the oil.

The fixing film 603 is a cylindrical film for applying heat and pressure to the toner image on the recording material at the nip portion N. As shown in FIG. In this embodiment, an elastic layer 603b and a release layer 603c are provided on the substrate 603a, and an inner surface sliding layer 603d is provided on the inner surface of the substrate 603a. Specifically, a cylindrical member made of a nickel alloy having an outer diameter of 30 mm, a length of 340 mm, and a thickness of 30 μm is used as the base material 603a. Further, a silicone rubber layer having a thickness of 400 μm is formed as an elastic layer 603b on the base material 603a, and a fluororesin tube having a thickness of about 20 μm is formed as a release layer 603c on the elastic layer 603b. Furthermore, a polyimide layer (PI layer) having a thickness of about 10 μm is used as the inner sliding layer 603d.

A heater holder 601 (hereinafter referred to as holder 601 ) is a member that holds the heater 600 pressed against the fixing film 603 . Further, the holder 601 has a semicircular cross-sectional shape, and has a function of regulating the rotational trajectory of the fixing film 603 . A highly heat-resistant resin or the like is used for the heater holder 601, and in this embodiment, Zenite 7755 (trade name) manufactured by DuPont is used.

A support stay 602 is a member that supports the heater 600 via the heater holder 601 . The support stay 602 is desirably made of a material that does not easily bend even when a large load is applied, and stainless steel (SUS304) is used in this embodiment.

As shown in FIG. 3, the support stay 602 is supported by flanges 411a and 411b at both ends in the longitudinal direction. The flanges 411a and 411b are collectively called a flange 411. As shown in FIG. The flange 411 regulates the longitudinal movement and circumferential shape of the fixing film 603 . A heat-resistant resin or the like is used for the flange 411, and polyphenylene sulfide (PPS) is used in this embodiment. A compressed pressure spring 415 is provided between the flange 411 and the pressure arm 414 . With the above configuration, the elastic force of the pressure spring 415 is transmitted to the heater 600 via the flange 411 and the support stay 602 . Then, the fixing film 603 is pressed against the pressure roller 70 with a predetermined pressing force, and a nip portion N having a predetermined width is formed. The applied pressure in this embodiment is about 156.8 N on one end side, and the total applied pressure is about 313.6 N (32 kgf).

Further, the connector 500 is a power supply member electrically connected to the heater 600 in order to apply a voltage to the heater 600, and is detachably attached to one end of the heater 600 in the longitudinal direction.

As shown in FIG. 2, the pressure roller 70 is a member that forms the nip portion N by being pressed against the fixing film unit 60 . The pressure roller 70 has a multi-layer structure in which an elastic layer 72 is provided on a metal core 71 and a release layer 73 is provided on the elastic layer 72 . As the cored bar 71, stainless steel (SUS), sulfur and sulfur composite free-cutting steel (SUM), and aluminum can be used. Silicone rubber, sponge rubber, or elastic foam rubber can be used as the elastic layer 72 . A fluorine resin material such as tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) can be used for the release layer 73 . The pressure roller 70 of this embodiment comprises a metal core 71 made of stainless steel, an elastic layer 72 made of silicone rubber, and a release layer 73 made of PFA tube. be.

As shown in FIG. 3, the core metal 71 of the pressure roller 70 is rotatably held via the side plate 41 and the bearings 42a and 42b. The driving force of the motor M93 is transmitted to the core metal 71. As shown in FIG. 2, the pressure roller 70 driven by the fixing driving motor M93 is rotationally driven in the direction of the arrow, and the driving force is transmitted to the fixing film 603 at the nip portion N so that the fixing film 603 is driven to rotate. In this embodiment, the fixing drive motor M93 is controlled by the control circuit section 90 so that the surface speed of the pressure roller 70 is 200 mm/sec. A thermistor (TH) 630, which is temperature detecting means shown in FIG. The thermistor 630 is connected to the control circuit section 90 via the A/D converter 80 and transmits an output corresponding to the detected temperature to the control circuit section 90 . The control circuit unit 90 is a circuit provided with a non-volatile medium such as a CPU and a ROM for performing calculations associated with various controls. Programs are stored in the ROM, and various controls are executed by reading and executing the programs by the CPU.

The control circuit section 90 is electrically connected to the power supply so as to control the energization of the power supply. In addition, the control circuit unit 90 reflects the temperature information acquired from the thermistor 630 in power supply control of the power supply, thereby controlling the power supplied to the heater 600 . In this embodiment, a method is used in which the amount of heat generated by the heater 600 is adjusted by performing wave number control or phase control on the power output. maintained.

[Current Detection Means for Fixing Drive Motor]
As shown in FIGS. 3 and 4, the motor current detection means 94 (torque information detection means) detects the current flowing through the fixing driving motor M93. The detected current value is input to the control circuit section 90 as sliding load information. In the present invention, since a brushless DC motor is used as the fixing drive motor M93, the torque is determined based on the motor current value, utilizing the characteristic that the drive current and torque of the motor are proportional. Based on this current value, the part to be replaced is specified from among the fixing device 40 . In this patent, the motor current detection method is used as the torque information detection means, but the method is not limited to this method, and torque information detection means such as a torque gauge may be used.

FIG. 4 is a block diagram showing the configuration of a rotation drive control system in the image forming apparatus.

The control circuit unit 90 drives and controls the heater energization circuit unit 92 based on the temperature of the fixing film 603 detected by the temperature detection unit 630 during the fixing operation (when the paper is passed). It has a function as temperature control means for controlling the temperature of the fixing device so as to approach a predetermined fixing temperature. The control circuit unit 90 also controls the rotation of the fixing film 603 and the pressure roller 70 by controlling the rotation of the fixing drive motor 93 based on the temperature of the fixing film 603 detected by the temperature detection means 630 . It has a function as a drive control means for driving.

Furthermore, the control circuit section 90 also has a function of notifying the user of the determination result by the determination means via the notification section. As the notification unit, for example, notification by displaying a message on the display panel of the image forming apparatus, notification by a buzzer sound such as an electronic buzzer, notification by a voice message from an internal speaker by voice synthesis, and the like are conceivable.

[Factors of sliding load increase (torque increase) and temperature dependence of torque]
FIG. 13 shows factors that increase the sliding load. Roughly classified, the film unit 60 factor and the pressure roller 70 factor are included. Each will be described in detail below.

Factors of the film unit 60 include deterioration of grease and contamination of scraped dust (abrasion dust). Grease deterioration is the loss of the base oil component (oil) that makes up the grease. It occurs when the grease is exposed to high temperatures for a long period of time, and the loss is accelerated by the evaporation or decomposition of the base oil (oil). will be When the deterioration of the grease is accelerated, the oil film between the fixing film 603 and the heater 600 becomes thinner, and the inner surface of the fixing film 603 contacts the heater 600 more frequently. As a result, abrasion of the inner surface of the film is accelerated, and abrasion dust (abrasion dust) is mixed in the grease interposed between the fixing film 603 and the heater 600 . Shaving dust (abrasion dust) is a factor that hinders the formation of an oil film between the fixing film 603 and the heater 600, leading to an increase in sliding load (torque increase).

On the other hand, factors of the pressure roller 70 include hardness reduction due to softening and deterioration of the elastic layer 72 with the passage of operating time of the fixing device 40, and shaft and bearing wear of the pressure roller 70 due to shaft shaving and bearing shaving. This is due to the contamination of abrasion powder.

FIG. 5 shows the temperature dependence of torque when the sliding load increases. When the sliding load increases due to the film unit 60 factor, in addition to the increase in the absolute value of the torque, the graph shape approaches the horizontal. It can be seen that the temperature dependence tends to decrease. Details will be described later. On the other hand, when the sliding load increases due to the pressure roller 70, the absolute value increases while maintaining the same trend as the normal graph shape (normal time without an increase in sliding load).

The present invention focuses on this phenomenon, and is characterized in that a replacement part is specified by performing a torque-up factor specifying operation based on this phenomenon. A detailed judgment flow will be described later.

[Temperature dependence of oil viscosity, temperature dependence of torque (presence or absence of lubricant)]
FIG. 6 shows the temperature dependence of kinematic viscosity characteristics of the base oil (oil) alone. Kinematic viscosity is the value obtained by dividing the viscosity by the density. It can be seen from FIG. 6 that the kinematic viscosity decreases as the temperature rises. This effect manifests itself as a phenomenon in the fixing device 40 in the sliding load (torque). FIG. 7 shows the temperature dependence of the sliding load (torque) in the fixing device 40. As shown in FIG. The sliding load on the vertical axis is a value obtained by converting the current value on the motor shaft into torque. It can be seen that the torque decreases as the temperature rises, and it can be seen that there is a tendency similar to the kinematic viscosity characteristics of the base oil shown in FIG. Next, FIG. 8 shows the temperature dependence of torque with and without grease. The no-grease state is a state simulating the above-described deteriorated state of the grease and the mixture of shavings. When there is no grease, there is no tendency for the torque to decrease as the temperature rises, and the graph is flat with little temperature dependence. This is because there is no grease, so the kinematic viscosity of the base oil (oil) alone does not affect it.

[Torque-up factor specific operation and judgment flow]
9 and 10 show schematic diagrams of the time-series transition of the sliding load. FIG. 9 is a schematic diagram of when the sliding load increases due to the film unit 60, and FIG. 10 is a schematic diagram of when the sliding load increases due to the pressure roller 70. In FIG. The temperature is heater temperature, and is data of two levels of low temperature (120° C.) condition and normal (200° C.) condition. The replacement part is identified by detecting the features shown in FIGS. 9 is the torque increase due to the film unit 60, so the temperature dependence is small, and FIG. 10 is the torque increase due to the pressure roller 70, so the temperature dependence is large. Become. A torque-up factor specifying operation and a judgment flow will be described with reference to FIG. 11 .

When a job is started, energization and driving are first started (S001). Next, it is determined whether or not the motor current value A is equal to or greater than a predetermined value (S002). If it is equal to or less than the predetermined value, it is determined that there is no problem in using the fixing device 40, and after executing the paper passing job (S003), power supply is stopped (S009), and the process ends.

On the other hand, if the motor current value A is equal to or greater than the predetermined value, the sheet feeding job is not executed, and after changing the temperature (S004), the motor current value B is obtained (S005). Next, it is determined whether or not the difference between the motor current value B and the motor current value A is equal to or greater than a predetermined value (S006). If the value is equal to or greater than the predetermined value, it is determined that the pressure roller 70 is the cause of the increase in the sliding load, and the pressure roller unit 70 is notified to be replaced (S008). If the difference between the motor current value B and the motor current value A is less than a predetermined value, it is determined that the film unit 60 is the cause of the increase in the sliding load, and the replacement of the film unit 60 is notified (S007), and the energization is stopped (S009). and end.
By executing the above steps (S002), (S004), (S005), and (S006), the cause of the torque increase is diagnosed.

The processing from (S001) to (S009) is implemented by the control circuit unit 90 executing the processing. Instructions to the user are displayed on the UI by a display device (not shown), and instructions from the user, service personnel, etc. are accepted from the input.

FIG. 12 shows a display example of displaying the determination result on a display device (not shown). FIG. 12 shows an example of the case where the film unit needs to be replaced due to the torque increase of the film unit 60 factor, and a message and coded information are displayed as specific words so that users and service personnel can understand. doing. In this way, since the content of the replacement part can be known from the specific information, the user, the serviceman, or the like can easily replace the target part.

In this embodiment, the result of the increase in the sliding load and the unit to be replaced are displayed on the display means to inform the user and service personnel, but the present invention is not limited to this. For example, a method of notifying the serviceman via a network may be adopted. In this case, the serviceman can know the parts to be replaced in advance, so that the parts to be replaced are surely carried and maintenance is performed. It can be carried out.

[Effect of Example 1]
As described above, it is possible to identify parts to be replaced in accordance with an increase in sliding load from the fixing device 40, and it is possible to reduce costs because only the specific parts need to be replaced.

1 image forming apparatus, 40 fixing device, 60 film unit,
70 pressure roller, 90 control circuit section, 92 heater energization circuit section,
93 fixing driving motor, 94 motor current detecting means, 603 fixing film

Claims (3)

a rotatable first rotating body that is in contact with the toner image on the recording material and heats the toner image;
a second rotating body in contact with the first rotating body;
The second rotating body forms a nip portion together with the first rotating body, and the nip portion applies heat and pressure to the toner image to fix the toner image on the recording material,
oil applied to the inner peripheral surface of the first rotating body;
driving means for rotating at least one of the first rotating body and the second rotating body;
a detection unit that acquires information about the torque of the driving means;
permitting a fixing operation when the information detected by the detection unit is equal to or less than a first threshold;
When the information detected by the detection unit is greater than the first threshold, the fixing operation is not permitted, and the detection unit detects the first information and the second information,
the temperature of the first rotating body when the first information is detected is higher than the temperature of the first rotating body when the second information is detected;
When the difference between the first information and the second information is equal to or less than a second threshold, a notification is provided to prompt replacement of the first rotating body, and when the difference is greater than the second threshold, the first 1. An image forming apparatus, comprising: a notification unit that performs notification to prompt replacement of a two-rotating body. When the difference between the first information and the second information is equal to or less than the second threshold, a display prompting replacement of the first rotor is displayed, and when the difference is greater than the second threshold, the first 2. The image forming apparatus according to claim 1, further comprising a display section for displaying a prompt to replace the two-rotating body. the driving means comprises a motor;
3. The image forming apparatus according to claim 1, wherein the detector detects current flowing through the motor.

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