JP2010026435A - Fixing device and image forming apparatus equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device whose life is accurately determined regardless of user's using condition. <P>SOLUTION: The fixing device includes a fixing member 12 having a releasing layer on its surface, and a pressure member 17 arranged to be opposed to the fixing member 12, wherein a toner image on a recording medium P is fixed and also the recording medium P is held and conveyed by a fixing nip N formed by the fixing member 12 and the pressure member 17, and either or both of the fixing member 12 and the pressure member 17 are formed of a belt member. The fixing device includes a tension roller 16 tensioning the belt member on the outside of the belt member, and has a position detection means 19 detecting the position of the tension roller 16. When the tension roller 16 bites into the belt member further than a predetermined position, based on a result of detection by the position detection means 19, it is determined as the end of the life. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fixing device for fixing an image by heating and pressurizing an image formed on a recording medium, and image formation of a PPC (plain paper) copying machine, a facsimile, a laser printer, and the like equipped with the fixing device. It relates to the device.

In an image forming apparatus, the quality of a fixed image is greatly influenced by the width of a fixing nip formed by a fixing member and a pressure member, so-called nip width. Fluctuates due to changes in hardness.
In a configuration in which a fixing roller and a pressure roller contact each other, which is generally called a roller fixing system, when the roller is pressed with a constant load, when the roller hardness decreases, the amount of biting between the rollers increases and the nip width increases. Increase. For this reason, the fixing parameter is changed by changing the position of the fixing roller and the pressure roller to stabilize the fixed image quality, the distance between the fixing roller and the pressure roller is kept constant, the roller hardness decreases with time, and the amount of biting is reduced. Some have been proposed that prevent the nip width from increasing and the like (see, for example, Patent Document 1).
However, in the so-called belt fixing method in which the belt is wound around the fixing roller with tension, when the distance between the fixing roller and the pressure roller is constant, the nip width decreases when the fixing roller hardness decreases.
This is because the elastic body in the vicinity of the nip inlet and the outlet is deformed by the belt tension and is separated from the pressure roller due to the decrease in hardness of the elastic body.

FIG. 14 is a schematic diagram for explaining the nip change in the belt fixing system. With reference to FIGS. 14A to 14D, the nip change in the belt fixing method will be described.
14A to 14D, a belt member 101 is wound around the fixing roller 100, and the pressure roller 102 is in pressure contact with the fixing roller 100 via the belt member 101.
14A shows a case where there is no change with time and the fixing roller 100 has an initial diameter (standard state), and FIG. 14B shows that the diameter of the fixing roller 100 changes with time and becomes smaller. In the state shown in FIG. 14 (a) to FIG. 14 (b), the nip width is reduced.
14C shows a case where the fixing roller 100 does not change over time and the roller hardness is in an initial standard state, whereas FIG. 14D shows the hardness of the fixing roller 100 due to change over time. 14 shows a case in which the nip width decreases when the state shown in FIG. 14C is changed to the state shown in FIG. 14D. Particularly, in the case of a fixing device using a sponge roller as the fixing roller 100, the nip width is greatly reduced due to a decrease in the hardness of the sponge roller over time, and a fixing failure occurs. Therefore, the fixing device can be replaced immediately before the decrease in the hardness. Necessary.

In general, the life of the fixing device is determined based on the number of sheets to be passed and the driving time. However, the decrease in the hardness of the sponge roller varies greatly depending on user conditions. For example, since the transfer paper is cold in a low temperature environment, it is used with a high fixing temperature. Compared with the case where the fixing temperature is low, the hardness of the sponge roller is greatly reduced even with the same number of sheets.
Japanese Patent Application Laid-Open No. 2004-228688 proposes a technique for disposing a sensor after the fixing nip, measuring the time to reach the sensor position, directly detecting deterioration of the fixing device by the change, and determining the life of the fixing device. . In this technique, the transfer paper is wound around the fixing member at the fixing outlet over time, and the life is determined based on the degree of winding.
Further, although not a known technique, a technique for changing the fixing temperature, the linear velocity, and the like depending on the position of the tension roller has been studied. According to this technique, the life cannot be determined, but the life of the fixing device can be accurately determined.
JP 2005-257781 A

However, according to the technique of Patent Document 1, even when plain paper is discharged in a wrapping manner over time, when the thick paper is passed, the paper is discharged without being wound around the fixing member because of its high rigidity. For this reason, the lifetime may not be determined.
As described above, it has been difficult to accurately determine the lifetime regardless of the use conditions of the user, and when the fixing device is replaced every time a predetermined number of sheets are output, the fixing device that can be used still has a lifetime. When the fixing device is replaced after a problem such as a paper jam or a fixing failure occurs, there is a problem that the downtime of the image forming apparatus becomes large.
In view of the above-described circumstances, an object of the present invention is to reduce the hardness of the fixing roller or to prevent the fixing roller from being lowered or removed when the tension roller bites into the fixing belt more than a predetermined position in the image forming apparatus having the fixing device. It is an object of the present invention to provide a fixing device and an image forming apparatus equipped with the fixing device that accurately determine the lifetime regardless of the use conditions of the user by determining that the fixing nip is less than a specified value due to the decrease in diameter. .

In order to solve the above problems, the invention described in claim 1 includes a fixing member having a release layer on a surface thereof, and a pressure member disposed to face the fixing member. In a fixing device that fixes a toner image on a recording medium at a fixing nip formed by the pressing member and sandwiches and conveys the recording medium, one or both of the fixing member and the pressing member are belt members. Comprising a tension applying member for applying tension to the belt member on the outside of the belt member, and having a position detecting means for detecting the position of the tension applying member, according to the detection result of the position detecting means, The fixing device is characterized in that when the tension applying member bites into the belt member more than a predetermined position, the fixing device determines that the life has been reached.
The invention according to claim 2 is characterized in that the fixing member is a belt member, and the tension applying member is a fixing tension roller for applying tension to the belt member.
According to a third aspect of the present invention, there is provided a rate-of-change calculating means for calculating a rate of change of the position of the fixing tension roller with respect to the number of passing sheets, and a remaining life calculating means for calculating the remaining life of the fixing device from the calculated value. The fixing device according to claim 1, further comprising a disclosure unit that displays or discloses the remaining life to the outside of the image forming apparatus.
According to a fourth aspect of the invention, there is provided the fixing device according to any one of the first to third aspects, wherein the change rate calculating means calculates a change rate with respect to a usage time of the position of the fixing tension roller. To do.

The invention according to claim 5 is characterized in that the pressure member comprises a belt member, and the tension roller is a pressure tension roller that applies tension to the belt member. .
The invention according to claim 6 is characterized in that the change rate calculating means calculates the change rate with respect to the number of sheets passing through the position of the pressure tension roller.
According to a seventh aspect of the present invention, there is provided the fixing device according to the fifth aspect, wherein the rate of change calculation means calculates a rate of change of the position of the pressure tension roller with respect to usage time.
According to an eighth aspect of the invention, there is provided the fixing device according to the first aspect, wherein both the fixing member and the pressure member are belt members.
According to a ninth aspect of the present invention, one of the fixing member and the pressure member is a belt member, and one of the fixing member and the pressure member opposite to the belt member is a fixed pad. A fixing device according to claim 1 is characterized.
According to a tenth aspect of the present invention, the electrostatic latent image formed on the latent image carrier is visualized by developing with toner, the toner image is transferred onto a recording medium, and the toner on the recording medium is transferred. An image forming apparatus for fixing an image on the recording medium by heat and pressure, wherein the fixing apparatus according to any one of claims 1 to 9 is mounted as a fixing apparatus for fixing the toner image on the recording medium. Features a forming device.

  According to the present invention, when the position of the tension roller bites into the belt more than a predetermined position, it is determined that the fixing nip is less than the specified value due to a decrease in the hardness of the fixing roller or a decrease in the outer diameter. The life of the fixing device can be accurately determined regardless of the use conditions.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view showing an image forming apparatus to which the present invention is applied. In FIG. 1, the image forming process of the image forming apparatus applies a charge to the photosensitive drums 1Y, 1C, 1M, and 1Bk, which are photosensitive members, to uniformly charge the photosensitive drums.
By irradiating the charged surface with a laser from an exposure device (not shown), a part of the photosensitive drums 1Y, 1C, 1M, and 1Bk is exposed and discharged to develop an electrostatic latent image formed. The toner on the developing rollers 3Y, 3C, 3M, and 3Bk of the devices 2Y, 2C, 2M, and 2Bk is moved to form a toner image.
In the case of a color image forming apparatus, an image forming unit (a set of photosensitive drums 1Y, 1C, 1M, and 1Bk and developing devices 2Y, 2C, 2M, and 2Bk) includes black toner, yellow toner, cyan toner, and magenta toner. The four toners are arranged as shown in FIG. 1 or four developing devices are arranged on one photosensitive drum to form a toner image. The toner image formed on the photosensitive drum is transferred onto the intermediate transfer belt 5 of the opposing transfer device 4.

The intermediate transfer belt 5 is stretched by a secondary transfer bias roller 6 and a support roller 7 that also serve as a support roller, and can rotate counterclockwise in the illustrated embodiment. When toner images are formed on the photosensitive drums 1Y, 1C, 1M, and 1Bk, voltages are applied to the primary transfer rollers 8Y, 8C, 8M, and 8Bk corresponding to the respective colors, and the photosensitive drums 1Y, 1C, and 1M are applied. 1Bk toner images are sequentially transferred onto the intermediate transfer belt 5.
A secondary transfer bias roller 6 also serving as the above-described support roller is disposed inside the intermediate transfer belt 5, and the secondary transfer unit 9 is opposed to the secondary transfer bias roller 6 with the intermediate transfer belt 5 interposed therebetween. Has been placed.
A registration roller pair 10 which is a part of the transfer paper transport device is disposed upstream of the secondary transfer unit. The registration roller pair 10 temporarily stops and holds a transfer sheet, which is a recording medium conveyed from a paper feeding device (not shown), and waits until the transfer timing, that is, preparation for the transfer operation is completed.
The registration roller pair 10 is driven at a transfer timing in accordance with the toner image on the intermediate transfer belt 5, and the toner image formed by the secondary transfer unit 9 and the intermediate transfer belt 5 passes through the secondary transfer unit 9 to be transferred. It is transferred to paper.
A general fixing device 11 that also serves as a conveying device is disposed downstream of the transfer device. The transfer paper on which the toner image is fixed with heat and pressure in the fixing device 11 is discharged to the outside through a paper discharge roller (not shown).

FIG. 2 is a schematic view showing a first embodiment of a fixing device according to the present invention. This fixing device 11 has a fixing belt 14 of φ75 which is a belt member whose surface is covered with a PFA tube as a release layer, a fixing roller 14 of foamed silicon rubber of φ40, and a halogen heater 13 included therein. There is an aluminum fixing heating roller 15. Outside the fixing belt 12, there is a φ12 fixing tension roller 16 whose surface is covered with a PFA tube.
The fixing tension roller 16 is a tension applying member that applies tension to the fixing belt 12 from the outside by a tension spring 17. A displacement sensor 19 for detecting the amount of displacement of the fixing tension roller 16 is disposed on the side of the fixing tension roller 16 away from the fixing belt 12. A laser displacement meter is used as the displacement sensor 19. The process linear velocity of this image forming apparatus is 322 mm / sec.
The pressure roller 17 is a second roller member in which a halogen heater 18 is disposed and is pressed against the lower portion of the fixing roller 14 via the fixing belt 12. A fixing nip N is formed by the pressure roller 17 and the fixing roller 14 with the fixing belt 12 interposed therebetween. FIG. 2 further shows the transfer paper P, the roller linear velocity Vr, the nip width Nt, the toner Go before fixing on the transfer paper P, and the toner G after fixing.

The displacement sensor 19 is a detection means that is arranged on the side of the fixing tension roller 16 and is composed of a laser displacement meter. The displacement sensor 19 detects the amount of displacement of the fixing tension roller 16, that is, the amount of biting of the fixing tension roller 16 into the fixing belt 12. .
A CPU (central processing unit) 20 which is a control unit controls the operation of each part of the apparatus. In this embodiment, the CPU 20 receives detection information from the displacement sensor 19 and performs arithmetic processing. Heat generation / heating of the heaters 13 and 18 is controlled via the heater driving members 21 and 22, and the fixing roller 14 and the pressure roller 17 are controlled via the roller driving units 23 and 24.
The function of the CPU 20 includes a function as a rate of change calculating means for calculating a rate of change of the tension roller position with respect to the number of sheets passed, a function as a remaining life calculating means for calculating the remaining life of the fixing device from the calculated value, It has a function as a disclosure means for displaying the remaining life or disclosing it outside the image forming apparatus.
FIG. 3 is a graph showing the relationship between the displacement amount of the fixing tension roller from the initial state and the nip width, and the lower limit nip width (10.3 mm) at which fixing quality can be ensured in the fixing device. In the drawing, the displacement amount of the fixing tension roller 16 indicates that the fixing nip width decreases as the numerical value increases.

FIG. 4 is a flowchart showing the operation of the fixing device according to the present invention. In FIG. 4, when the print signal is on, a fixing motor (not shown) is turned on (S1). It is determined whether 1 second has elapsed after the fixing motor is turned on (S2). If 1 second has elapsed, the displacement amount X of the fixing tension roller 16 (not shown) is measured (S3).
Next, paper feeding is started (S4), an image forming operation is performed (S5), it is determined whether or not the job is finished (S6), and then it is determined whether or not the displacement amount of the fixing tension roller 16 is 8 mm or more (S6). S7) When the displacement amount of the fixing tension roller 16 is detected to be 8 mm or more, it is determined that the fixing device has reached the end of its life, and “Replace fixing unit” is displayed on the display panel of the operation unit of the image forming apparatus (not shown). Then, the fixing motor is turned off (S9).
In the present invention, if the position of the fixing tension roller 16 bites into the fixing belt 11 more than a predetermined position, it is determined that the fixing nip is less than a specified value due to a decrease in the hardness of the fixing roller 14 or a decrease in outer diameter. As a result, the life of the fixing device can be accurately determined regardless of the use conditions of the user.

FIG. 5 is a flowchart showing the first embodiment of the operation of the fixing device according to the present invention. In FIG. 5, when the print signal is on, a fixing motor (not shown) is turned on (S11). It is determined whether 1 second has elapsed after the fixing motor is turned on (S12). If 1 second has elapsed, the displacement amount X of the fixing tension roller 16 (FIG. 2) is measured (S13).
Next, it is determined whether or not the displacement amount X is 7 mm or more (S14). If the displacement amount X is 7 mm or more, the life prediction number counter is turned off (S15), and the remaining life (remaining life = life prediction number counter value) is set. Calculate (S16). If the displacement amount X is not 7 mm or more in step (S14), it is determined whether the displacement amount X is 6 mm or more (S17). If the displacement amount X is 6 mm or more, the life prediction sheet number counter is turned on (S18).
Next to step (S16) and step (S18), and if the displacement amount X is not 6 mm or more, paper feeding is started (S19), an image forming operation is performed (S20), and it is determined whether or not it is a job end ( Next, it is determined whether or not the displacement amount X of the fixing tension roller 16 is 8 mm or more (S22).
When the displacement amount X of the fixing tension roller 16 is detected to be 8 mm or more, it is determined that the fixing device has reached the end of life, and “Replace fixing unit” is displayed on the display panel of the operation unit of the image forming apparatus (not shown). S23). If the displacement amount X is not 8 mm or more in step (S22), it is determined whether or not the displacement amount X is 7 mm or more (S24). If the displacement amount X is 7 mm or more, “remaining life ○○ sheets” is displayed on the operation panel. The display is displayed (S25), and the fixing motor is turned off (S26) in the same manner as in the step (S23).

FIG. 6 is a graph showing the relationship between the fixing tension roller biting amount and the nip width. Referring to FIGS. 2 and 6, when the displacement amount (biting amount) of the fixing tension roller 16 is detected to be 6 mm or more, the “life prediction sheet number counter” is started. When the displacement amount of the fixing tension roller 16 is detected to be 7 mm or more, the “life expectation number counter” is stopped.
The number of sheets until the displacement amount of the fixing tension roller 16 reaches 7 mm, which is the life of the fixing device 11, is equal to the number of sheets required for the displacement amount of the fixing tension roller 16 to reach 7 mm from 6 mm. Therefore, the remaining life when the displacement amount of the fixing tension roller 16 reaches 7 mm is the value of the sheet counter from 6 mm to 7 mm, and the value is displayed on the operation unit display panel (not shown) as the number of sheets.
Further, when the displacement amount of the fixing tension roller 16 is detected to be 8 mm or more, it is determined that the fixing device 11 has reached the end of its life, and “Replace fixing unit” is displayed on the display panel of the operation unit of the image forming apparatus (FIG. 5). Step S23).
The remaining life of the fixing device 11 is calculated by the calculation means for calculating the rate of change of the position of the fixing tension roller 16 with respect to the number of sheets to be passed, and the remaining life of the fixing device 11 is displayed or disclosed outside the image forming apparatus. By informing the user of the number of remaining sheets that can be used and prompting the user to prepare for replacement of the fixing device, the downtime of the image forming apparatus can be shortened.

FIG. 7 is a flowchart showing a second embodiment of the operation of the fixing device according to the present invention. 2 and 7, when the print signal is on, the fixing motor is turned on (S31). It is determined whether or not 1 second has elapsed after the fixing motor (not shown) is turned on (S32), and if 1 second has elapsed, the displacement amount X of the fixing tension roller 16 is measured (S33).
Next, it is determined whether or not the displacement amount X is 7 mm or more (S34). If the displacement amount X is 7 mm or more, the life prediction timer is turned off (S35), and the remaining life (remaining life = life prediction number counter value) is calculated. (S36). If the displacement amount X is not 7 mm or more in step (S34), it is determined whether the displacement amount X is 6 mm or more (S37). If the displacement amount X is 6 mm or more, the life prediction timer is turned on (S38).
Next to step (S36) and step (S38), and if the displacement amount X is not 6 mm or more, paper feeding is started (S39), an image forming operation is performed (S40), and it is determined whether or not the job is ended (S40). Next, it is determined whether the displacement amount X of the fixing tension roller 16 (FIG. 2) is 8 mm or more (S42).
When the displacement amount X of the fixing tension roller 16 is detected to be 8 mm or more, it is determined that the fixing device has reached the end of life, and “Replace fixing unit” is displayed on the display panel of the operation unit of the image forming apparatus (not shown). S43). If the displacement amount X is not 8 mm or more in step (S42), it is determined whether or not the displacement amount X is 7 mm or more (S44). If the displacement amount X is 7 mm or more, “remaining life ○○ sheets” is displayed on the operation panel. The display is displayed (S45), and the fixing motor is turned off (S46) in the same manner as in the step (S43).

FIG. 8 is a graph showing the relationship between the fixing tension roller biting amount and the nip width. Referring to FIGS. 2 and 8, the “life prediction timer” is started when the displacement amount of the fixing tension roller 16 is detected to be 6 mm or more. When the displacement amount of the fixing tension roller 16 is detected to be 7 mm or more, the “life prediction timer” is stopped.
The number of sheets from the displacement amount of the fixing tension roller 16 to 8 mm, which is the life of the fixing device 11, is equivalent to the time required for the displacement amount of the fixing tension roller 16 to reach 7 mm from 6 mm. Therefore, the remaining life when the displacement amount of the fixing tension roller 16 reaches 7 mm is a timer value from 6 mm to 7 mm, and the value is displayed in time on an operation unit display panel (not shown). Further, when the displacement amount of the fixing tension roller 16 is detected to be 8 mm or more, it is determined that the fixing device 11 has reached the end of its life, and “Replace fixing unit” is displayed on the display panel of the operation unit of the image forming apparatus.
By calculating the remaining life of the fixing device 11 by calculating means for calculating the rate of change of the position of the fixing tension roller 16 with respect to the usage time, the remaining life of the fixing device 11 is displayed or disclosed outside the image forming apparatus. By notifying the user of the remaining usable time and prompting the user to prepare for replacing the fixing device, the downtime of the image forming apparatus can be shortened.

FIG. 9 is a schematic view showing a second embodiment of the fixing device according to the present invention. A pressure heating roller of φ30 aluminum in which a pressure roller 28 of φ40 foamed silicon rubber and a halogen heater 27 are included inside a pressure belt 25 of φ75 covered with a PFA tube as a release layer. There are 26.
Outside the pressure belt 25 is a φ12 pressure tension roller 16 whose surface layer is covered with a PFA tube. The pressure tension roller 16 has the same reference numeral as that of the first embodiment, but is provided for the pressure belt 25. Therefore, in the description of the second embodiment, the pressure tension roller 16 This will be described as 16.
The pressure tension roller 16 applies tension to the pressure belt 25 by a tension spring 17. A displacement sensor 19 that detects the amount of displacement of the pressure tension roller 16 is disposed on the side of the pressure tension roller 16 away from the pressure belt 25. A laser displacement meter is used as the displacement sensor 19.

The fixing device 11 includes a fixing roller 29 having a release layer on the surface, a pressure belt 25, a pressure heating roller 26 having an elastic layer inside the pressure belt 25, and a halogen that applies heat to the pressure belt 25. A heater 27 and a pressure tension roller 16 that applies tension to the pressure belt 25 are provided outside the pressure belt 25.
The fixing device 11 includes a holding member that keeps the distance between the fixing roller 29 that is a fixing member and the pressure belt 25 that is a pressure member constant (for example, the shaft of the fixing roller 29 and the shaft of the pressure roller are spaced at a fixed interval). The toner frame on the recording medium is fixed at the fixing nip N formed by the fixing roller 29 and the pressure roller 28, and the recording medium is fixed. Nipped and conveyed.
When the pressure tension roller 16 has a position detecting means 19 for detecting the position of the pressure tension roller 16 and the pressure tension roller 16 bites into the pressure belt 25 from a predetermined position, the hardness of the pressure roller 28 decreases or the outer diameter decreases. Thus, by determining that the fixing nip N is less than the standard, it is possible to accurately determine the life of the fixing device 11 regardless of the use conditions of the user.

FIG. 9 further shows the transfer paper P, the roller linear velocity Vr, the nip width Nt, the toner Go before fixing on the transfer paper P, and the toner G after fixing. The displacement sensor 19 is a detection means that is arranged on the side of the fixing tension roller 16 and is composed of a laser displacement meter. The displacement sensor 19 detects the amount of displacement of the fixing tension roller 16, that is, the amount of biting of the fixing tension roller 16 into the fixing belt 12. .
A CPU (central processing unit) 20 which is a control unit controls the operation of each part of the apparatus. In this embodiment, the CPU 20 receives detection information from the displacement sensor 19 and performs arithmetic processing. Heat generation / heating of the heaters 13 and 18 is controlled via the heater driving members 21 and 22, and the fixing roller 14 and the pressure roller 17 are controlled via the roller driving units 23 and 24.
The function of the CPU 20 includes a function as a rate of change calculating means for calculating the rate of change of the position of the pressure tension roller 16 with respect to the number of sheets to be passed, and a function of calculating the remaining life of the fixing device from the calculated value. It has a function as a disclosure means for displaying or disclosing the remaining life to the outside of the image forming apparatus.

FIG. 10 is a flowchart showing the operation of the fixing device of the present invention according to FIG. 9 and 10, when the print signal is on, the fixing motor is turned on (S51). It is determined whether or not 1 second has elapsed after the fixing motor (not shown) is turned on (S52), and if 1 second has elapsed, the displacement amount X of the pressure tension roller 16 (not shown) is measured (S53).
Next, paper feeding is started (S54), an image forming operation is performed (S55), and it is determined whether or not it is a job end (S56). Next, it is determined whether or not the displacement amount of the pressure tension roller 16 is 8 mm or more. (S57) When the displacement amount of the pressure tension roller 16 is detected to be 8 mm or more, it is determined that the fixing device has reached the end of its life, and “fixing UNIT replacement” is displayed on the display panel of the operation unit of the image forming apparatus (not shown). Is displayed (S58), and the fixing motor is turned off (S59).
When the pressure tension roller 16 has a detecting means 19 for detecting the position of the pressure tension roller 16 and the pressure tension roller 16 bites into the pressure belt 25 from a predetermined position, the hardness of the pressure roller 28 decreases or the outer diameter decreases. By determining that the fixing nip N is less than the standard, it is possible to accurately determine the life of the fixing device regardless of the use conditions of the user.

FIG. 11 is a flowchart showing a first embodiment of the operation of the fixing device shown in FIG. 9 and 11, the print motor is turned on and a fixing motor (not shown) is turned on (S61). It is determined whether 1 second has elapsed after the fixing motor is turned on (S62). If 1 second has elapsed, the displacement amount X of the pressure tension roller 16 is measured (S63).
Next, it is determined whether or not the displacement amount X is 7 mm or more (S64). If the displacement amount X is 7 mm or more, the life prediction number counter is turned off (S65), and the remaining life (remaining life = life prediction number counter value) is set. Calculate (S66). If the displacement amount X is not 7 mm or more in step (S64), it is determined whether the displacement amount X is 6 mm or more (S67). If the displacement amount X is 6 mm or more, the life prediction sheet counter (CPU 20) is turned on (S68). ).
Next to step (S66) and step (S68), and if the displacement amount X is not 6 mm or more, paper feeding is started (S69), an image forming operation is performed (S70), and it is determined whether or not it is a job end ( Next, it is determined whether or not the displacement amount X of the pressure tension roller 16 is 8 mm or more (S72).

When the displacement amount X of the pressure tension roller 16 is detected to be 8 mm or more, it is determined that the fixing device 11 has reached the end of its life, and “Replace fixing unit” is displayed on the display panel of the operation unit of the image forming apparatus (not shown). (S73). If the displacement amount X is not 8 mm or more in step (S72), it is determined whether or not the displacement amount X is 7 mm or more (S74). If the displacement amount X is 7 mm or more, “remaining life ○○ sheets” is displayed on the operation panel. The display is displayed (S75), and the fixing motor is turned off (S76) in the same manner as in the step (S73).
That is, when the displacement amount of the pressure tension roller 16 is detected to be 6 mm or more, the “predictable life counter” is started. When the displacement amount of the pressure tension roller 16 is detected to be 7 mm or more, the “life prediction number counter” is stopped.
The number of sheets until the displacement amount of the pressure tension roller 16 reaches 7 mm, which is the life of the fixing device, is equal to the number of sheets required for the displacement amount of the pressure tension roller 16 to reach 7 mm from 6 mm. For this reason, the remaining life when the displacement amount of the pressure tension roller 16 reaches 7 mm becomes the value of the sheet counter from 6 mm to 7 mm, and the value is displayed on the operation unit display panel as the number of sheets.

Further, when the displacement amount of the pressure tension roller 16 is detected to be 8 mm or more, it is determined that the fixing device 11 has reached the end of life, and “fixing UNIT replacement” is displayed on the display panel of the operation unit of the image forming apparatus.
As described above, in the present embodiment, the change rate calculation means (CPU 20) that calculates the change rate with respect to the number of sheets passing through the position of the pressure tension roller 16 and the remaining life of the fixing device 11 are calculated from the calculated value. The remaining life calculating means (CPU 20) for displaying and the disclosing means (CPU 20) for displaying or disclosing the remaining life of the fixing device 11 to the outside of the image forming apparatus.
Accordingly, the remaining life of the fixing device 11 is calculated by a manual change rate calculation stage (CPU 20) that calculates the change rate of the position of the pressure tension roller 16 with respect to the number of sheets passed, and the remaining life of the fixing device 11 is displayed or imaged. By disclosing outside the forming apparatus, the user can be informed of the remaining number of sheets that can be used and urged to prepare for replacement of the fixing apparatus, thereby reducing the downtime of the image forming apparatus.

FIG. 12 is a flowchart showing a second embodiment of the operation of the fixing device according to the present invention. In FIG. 12, when the print signal is on, the fixing motor is turned on (S81). It is determined whether 1 second has elapsed after the fixing motor is turned on (S82), and if 1 second has elapsed, the displacement amount X of the pressure tension roller 16 is measured (S83).
Next, it is determined whether or not the displacement amount X is 7 mm or more (S84). If the displacement amount X is 7 mm or more, the life prediction timer (CPU 20) is turned off (S85), and the remaining life (remaining life = life prediction number counter value). ) Is calculated (S86). If the displacement amount X is not 7 mm or more in step (S84), it is determined whether the displacement amount X is 6 mm or more (S87). If the displacement amount X is 6 mm or more, the life prediction timer is turned on (S88).
After step (S86) and step (S88), and if the displacement amount X is not 6 mm or more, paper feeding is started (S89), an image forming operation is performed (S90), and it is determined whether or not it is a job end ( Next, it is determined whether or not the displacement amount X of the pressure tension roller 16 is 8 mm or more (S92).

When the displacement amount X of the pressure tension roller 16 is detected to be 8 mm or more, it is determined that the fixing device has reached the end of its life, and “Replace fixing unit” is displayed on the display panel of the operation unit of the image forming apparatus (not shown). (S93). If the displacement amount X is not 8 mm or more in step (S92), it is determined whether or not the displacement amount X is 7 mm or more (S94). If the displacement amount X is 7 mm or more, “remaining life XX sheets” is displayed on the operation panel. The display is displayed (S95), and the fixing motor is turned off (S96) in the same manner as in the step (S93).
That is, the “life prediction timer” is started when the displacement amount of the pressure tension roller 16 is detected to be 6 mm or more. When the displacement amount of the pressure tension roller 16 is detected to be 7 mm or more, the “life prediction timer” is stopped.
The number of sheets until the displacement of the pressure tension roller 16 reaches 7 mm from the displacement of the pressure tension roller 16 reaches 8 mm which is the life of the fixing device 11 is equal to the time required for the displacement of the pressure tension roller 16 to reach 7 mm from 6 mm. Therefore, the remaining life when the displacement amount of the pressure tension roller 16 reaches 7 mm becomes a timer value from 6 mm to 7 mm, and the value is displayed on the operation unit display panel with time.

When the displacement amount of the pressure tension roller 16 is detected to be 8 mm or more, it is determined that the fixing device has reached the end of its life, and “fixing UNIT replacement” is displayed on the display panel of the operation unit of the image forming apparatus.
As described above, in this embodiment, the change rate calculating means (CPU 20) for calculating the change rate of the position of the pressure tension roller 16 with respect to the usage time, and the remaining life for calculating the remaining life of the fixing device 11 from the calculated value. It has a life calculation means (CPU 20) and a disclosure means (CPU 20) for displaying or disclosing the remaining life of the fixing device 11 outside the image forming apparatus.
Accordingly, the remaining life of the fixing device 11 is calculated by a change rate calculating means for calculating the change rate of the position of the pressure tension roller 16 with respect to the usage time, and the remaining life of the fixing device 11 is displayed or displayed outside the image forming apparatus. By disclosing, it is possible to shorten the downtime of the image forming apparatus by informing the user of the remaining usable time and prompting the user to prepare for replacement of the fixing device.

FIG. 13 is a schematic view showing a fixing device having two belt members. As shown in FIG. 13, in this embodiment, the fixing device 11 includes a fixing belt 31 that is a fixing member made of a belt member and a pressure belt 32 that is a pressure member made of a belt member. .
Although not shown in the drawings, the present invention is also applicable to a configuration in which either the fixing member or the pressure member is a belt member, and either the fixing member or the pressure member facing the fixing member is a fixed pad. A suitable fixing device can be obtained by application.

1 is a schematic diagram illustrating an image forming apparatus to which the present invention is applied. 1 is a schematic diagram illustrating a first embodiment of a fixing device according to the present invention. FIG. 6 is a graph showing a relationship between a displacement amount of a fixing tension roller from an initial state and a nip width, and a lower limit nip width (10.3 mm) at which fixing quality can be secured in the fixing device. 3 is a flowchart showing the operation of the fixing device according to the present invention. 3 is a flowchart illustrating a first embodiment of an operation of the fixing device according to the present invention. FIG. 6 is a graph showing the relationship between the amount of fixing tension roller biting and the nip width. 6 is a flowchart illustrating a second embodiment of the operation of the fixing device according to the present invention. FIG. 6 is a graph showing the relationship between the amount of fixing tension roller biting and the nip width. FIG. 6 is a schematic diagram illustrating a second embodiment of a fixing device according to the present invention. 10 is a flowchart showing the operation of the fixing device of the present invention according to FIG. 10 is a flowchart showing a first embodiment of the operation of the fixing device according to FIG. 9; 6 is a flowchart illustrating a second embodiment of the operation of the fixing device according to the present invention. It is a schematic diagram showing a fixing device having two belt members. It is the schematic explaining the change of the nip in a belt fixing system.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Latent image carrier (photosensitive drum), 2 Developing device, 5 Intermediate transfer belt, 11 Fixing device, 12 Fixing member (fixing belt), 14 Fixing roller, 15 Fixing heating roller, 16 Tension applying member (fixing or pressing) Tension roller), 17 pressure member (pressure roller), 19 position detection means (displacement sensor), 20 CPU (change rate calculation means, remaining life calculation means, disclosure means), 25 pressure member (pressure belt), 26 pressure heating roller, 28 pressure roller, 29 fixing member (fixing roller), 31 fixing member (fixing belt), 32 pressure member (pressure belt), N fixing nip, P recording medium

Claims (10)

  A fixing member having a release layer on the surface; and a pressure member disposed opposite to the fixing member; and a toner on a recording medium at a fixing nip formed by the fixing member and the pressure member. In a fixing device that fixes an image and sandwiches and conveys the recording medium, one or both of the fixing member and the pressure member is a belt member, and tension is applied to the belt member outside the belt member. A tension applying member; and a position detecting means for detecting the position of the tension applying member. According to a detection result of the position detecting means, when the tension applying member bites into the belt member more than a predetermined position, the life is shortened. A fixing device characterized by determining that it has been reached.   The fixing device according to claim 1, wherein the fixing member is a belt member, and the tension applying member is a fixing tension roller that applies tension to the belt member.   A rate of change calculating means for calculating a rate of change of the position of the fixing tension roller with respect to the number of sheets to be passed; a remaining life calculating means for calculating a remaining life of the fixing device from the calculated value; and displaying the remaining life or outside the image forming apparatus The fixing device according to claim 1, further comprising a disclosure unit disclosed in the above.   The fixing device according to claim 1, wherein the change rate calculation unit calculates a change rate with respect to a usage time of the position of the fixing tension roller.   The fixing device according to claim 1, wherein the pressure member is a belt member, and the tension applying member is a pressure tension roller that applies tension to the belt member.   The fixing device according to claim 1, wherein the change rate calculation unit calculates a change rate with respect to the number of passing sheets of the position of the pressure tension roller.   The fixing device according to claim 5, wherein the change rate calculating unit calculates a change rate with respect to a usage time of the position of the pressure tension roller.   The fixing device according to claim 1, wherein both the fixing member and the pressure member are belt members.   2. The fixing according to claim 1, wherein one of the fixing member and the pressure member is a belt member, and one of the fixing member and the pressure member facing the belt member is a fixing pad. apparatus.   The electrostatic latent image formed on the latent image carrier is developed and visualized with toner, the toner image is transferred onto a recording medium, and the toner image on the recording medium is transferred onto the recording medium by heat and pressure. An image forming apparatus for fixing, wherein the fixing device according to claim 1 is mounted as a fixing device for fixing the toner image on the recording medium.

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