JP7238625B2 - Fixing device and image forming device - Google Patents

Description

The present invention relates to a fixing device and an image forming apparatus.

In an electromagnetic induction heating type fixing device, a temperature detection means is arranged at a position different from the heat generating portion of an electromagnetic induction heating member for heating the fixing member, and the value detected by this temperature detection means and the integrated value of input power are used to determine the temperature. A technique for detecting rotation abnormality of a fixing member is known.

For example, in Patent Document 1, for the purpose of providing a fixing device and an image forming apparatus capable of detecting a behavior change factor of a fixing member that causes deformation or breakage of the fixing member, a heating portion of an electromagnetic induction heat generating member is disclosed. A technology is disclosed in which a temperature sensor is arranged downstream of the engine and a slip, which is an abnormal rotation, is detected based on the detection result of the temperature sensor.

If the thin fixing belt, which is the fixing member, rotates normally, when the recording material enters the fixing nip portion during continuous printing, the temperature of the fixing nip portion temporarily drops and then remains constant. When the temperature sensor is arranged on the downstream side of the heating region other than the heating region, as in the prior art disclosed in Patent Document 1, the fixing belt is heated, moves, supplies heat to the recording material, and then measures the temperature. is repeated, and the temperature detection by the temperature sensor during printing stabilizes, as in the n-th printing and the (n+1)-th printing in FIG. However, if the fixing belt does not rotate at the same speed as the pressure roller and slips, heat dissipation at the fixing nip (heat supply to the recording material) increases, and as a result, the temperature detected at the position of the temperature sensor decreases (n+2 sheet). printing). When the detected temperature information is lower than the set value in this way, the power supplied to the fixing device does not become constant as in the case of printing the nth and n+1st sheets in FIG. Like, get bigger.

In the configuration in which the temperature detection means is arranged at a position different from the heat generating part, the temperature drop is detected at a position different from the heat generating part, so the heat generating area/heating area, which is the information that the temperature rises the most and is desired for ensuring safety. The actual temperature cannot be known directly, and it is necessary to ensure safety by combining the input power integrated value (the power integrated value becomes higher when slipping). Part damage can occur depending on the condition.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fixing device capable of detecting a slight increase in slip and stopping the driving before a large slip that causes abnormal rotation occurs.

In order to solve the above-described problems, a fixing device according to the present invention includes a heating means, a fixing member heated and rotated by the heating means, and a pressure rotating body that presses against the fixing member to form a fixing nip portion. and a temperature detection means disposed in the range of the heat generation region of the heating means, wherein the number of times per predetermined time that the value detected by the temperature detection means exceeds a preset specified value is a preset specified When the number of times is exceeded, it is determined that the rotation is abnormal.

According to the present invention, it is possible to detect a minute increase in slip and stop driving the fixing device before a large slip that causes abnormal rotation occurs.

1 is a schematic diagram showing the overall configuration of an image forming apparatus according to one embodiment of the present invention; FIG. 1 is a schematic cross-sectional view of a main part of a fixing device according to an embodiment of the invention; FIG. It is a graph which shows a small slip as an output of a temperature sensor. FIG. 10 is a graph showing a torque rise over time, a temperature rise displacement amount, and a temperature rise occurrence rate, and a corresponding graph showing an increase in minute slip (temperature sensor output) over time; FIG. 4 is a flow chart showing an operation flow for detecting minute slips per predetermined time period and avoiding abnormal rotation. 6 is a flow chart showing a slip detection flow that can be used in conjunction with the slip detection flow of FIG. 5; 4 is a flow chart showing an operation flow for detecting a minute slip per predetermined number of sheets passed and avoiding the occurrence of abnormal rotation. To encourage failure avoidance actions when preliminary rotation abnormality is recognized again within a small number of passing sheets even if the fixing device is not replaced even if it is determined that there is a rotation abnormality and an alert is displayed. is a flow chart showing the operation flow of . After it is determined as a preliminary rotation abnormality, the number of sheets passed until the next preliminary rotation abnormality is determined, and when the recorded value is continuously below the specified value, failure can be avoided. 4 is a flow chart showing an operation flow for prompting an action; After it is determined that the rotation is abnormal, the number of sheets passed until the next time it is determined that the rotation is abnormal is recorded for a specified number of times. It is a flow chart which shows a flow. After it is determined that there is a rotation abnormality, the number of sheets passed until the next time it is determined that there is a rotation abnormality is recorded for a specified number of times. It is a flow chart which shows a flow. Operation flow that records the drive time for a specified number of times until the next determination of rotation abnormality after it is determined that there is a rotation abnormality, and when the average value of the recorded values falls below the specified value, it prompts the failure avoidance action. It is a flow chart showing. FIG. 13 is a flowchart showing an operation flow for starting monitoring and operation related to failure avoidance after the number of sheets passed exceeds a predetermined specified value, with respect to the operation flow of FIG. 12 ; FIG. 7 is a graph showing changes in temperature detected by a temperature sensor during continuous printing; 7 is a graph showing transition of input power to a fixing device when continuous printing is performed;

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing the overall configuration of an image forming apparatus according to an embodiment of the invention. The image forming apparatus 1 shown here is a color laser printer, and four image forming units 4Y, 4M, 4C, and 4K are provided at the center of the printer body. The image forming units 4Y, 4M, 4C, and 4K contain developers of different colors of yellow (Y), magenta (M), cyan (C), and black (K) corresponding to the color separation components of the color image. It has the same configuration except that

Specifically, each of the image forming units 4Y, 4M, 4C, and 4K includes a drum-shaped photoreceptor 5 as a latent image carrier, a charging device 6 that charges the surface of the photoreceptor 5, and a surface of the photoreceptor 5. and a cleaning device 8 for cleaning the surface of the photosensitive member 5, and the like. In FIG. 1, only the photosensitive member 5, the charging device 6, the developing device 7, and the cleaning device 8 provided in the image forming unit 4K for black are denoted by reference numerals. omitted.

An exposure device 9 for exposing the surface of the photoreceptor 5 is arranged below the imaging units 4Y, 4M, 4C, and 4K. The exposure device 9 has a light source, a polygon mirror, an f-.theta.

A transfer device 3 is arranged above the image forming units 4Y, 4M, 4C, and 4K. The transfer device 3 includes an intermediate transfer belt 30 , four primary transfer rollers 31 and secondary transfer rollers 36 . Further, the transfer device 3 includes a secondary transfer backup roller 32 , a cleaning backup roller 33 , a tension roller 34 and a belt cleaning device 35 . Here, as the secondary transfer backup roller 32 is driven to rotate, the intermediate transfer belt 30 circulates (rotates) in the direction indicated by the arrow in the figure.

The four primary transfer rollers 31 sandwich the intermediate transfer belt 30 with each photoreceptor 5 to form a primary transfer nip. Each primary transfer roller 31 is connected to the power source of the printer body, and a predetermined DC voltage (DC) and/or AC voltage (AC) is applied to each primary transfer roller 31 . . The secondary transfer roller 36 sandwiches the intermediate transfer belt 30 with the secondary transfer backup roller 32 to form a secondary transfer nip. Further, like the primary transfer roller 31 , the secondary transfer roller 36 is also connected to the power source of the printer main body, and a predetermined direct current (DC) and/or alternating voltage (AC) is applied to the secondary transfer roller 36 . It is designed to be

A bottle storage section 2 is provided in the upper portion of the printer main body, and four toner bottles 2Y, 2M, 2C, and 2K containing toner for replenishment are detachably attached to the bottle storage section 2.例文帳に追加As is well known, a supply path is provided between each toner bottle 2Y, 2M, 2C, 2K and each developing device 7. Through this supply path, each developer is supplied from each toner bottle 2Y, 2M, 2C, 2K. Toner is supplied to the device 7 .

On the other hand, a paper feed tray 10 containing paper P as a recording material, paper feed rollers 11 for carrying out the paper P from the paper feed tray 10, and the like are provided in the lower part of the printer main body.
In the main body of the printer, a transport path R is provided for discharging the paper P from the paper feed tray 10 through the secondary transfer nip to the outside of the apparatus. In the transport path R, a pair of registration rollers 12 as transport means for transporting the paper P to the secondary transfer nip are arranged upstream of the position of the secondary transfer roller 36 in the paper transport direction.

A fixing device 20 for fixing an unfixed image transferred to the paper P is arranged downstream of the position of the secondary transfer roller 36 in the paper transport direction. Further, a pair of paper ejection rollers 13 for ejecting the paper out of the device is provided downstream of the fixing device 20 in the paper transportation direction of the transportation path R. As shown in FIG. A paper discharge tray 14 for stocking the paper discharged outside the apparatus is provided on the upper surface of the printer main body.

The basic operation of the printer as described above is such that even when a full-color image is formed on paper, any one of the four imaging units 4Y, 4M, 4C, and 4K is used to form a monochrome image. , forming a two-color or three-color image using two or three image forming units, and for the sake of simplification, description of these operations will be omitted.

Next, the fixing device 20 will be described with reference to FIG. The fixing device 20 is an electromagnetic induction heating type fixing device driven by a pressure roller. , a rigid reinforcing member 23, a pressure roller 24 (pressure rotating body), and the like.

The fixing belt 21 has a substrate layer, an elastic layer, and a release layer which are sequentially laminated from the inner peripheral surface side, and the total thickness is set to 1 mm or less. The base layer has a layer thickness of 30 to 50 μm and is made of a metal material such as stainless steel or a resin material such as polyimide. The elastic layer has a layer thickness of 100 to 300 μm and is made of a rubber material such as silicone rubber. The release layer has a layer thickness of 10 to 50 μm and is made of a material such as PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer). Further, the diameter of the fixing belt 21 is set to be 15 to 120 mm.

Magnetic cores 25a, 25b, 25c and an exciting coil 26, which constitute electromagnetic induction heating means, are arranged and held inside the metal guide member 22, which is an electromagnetic induction heat generating member. The guide member 22 is heated by the induction heating means. The magnetic core 25 is a ferromagnetic material such as ferrite, and the exciting coil 26 is a Litz wire bundled with thin wires extending in the width direction (perpendicular to the paper surface of the drawing). A cylindrical fixing belt 21 is loosely fitted around the guide member 22 .

The pressure roller 24 is composed of a metal core 24a and a heat-resistant elastic material layer 24b concentrically formed around the metal core 24b in a roller-like shape. freely supported. The guide member 22, to which the fixing belt 21 is fitted, is arranged above the pressure roller 24, and is pushed down by a reinforcing member 23 inserted through the guide member 22 and arranged in contact with the inner bottom surface of the guide member. As a result, the lower surface of the guide member 22 and the upper surface of the pressure roller 24 are pressed against each other with the fixing belt 21 interposed therebetween to form a fixing nip portion N having a predetermined width.

The guide member 22 has a function of applying pressure to the fixing nip portion N, supporting the exciting coil 26 and the magnetic core 25 as magnetic field generating means, supporting the fixing belt 21, and stabilizing the transportation of the fixing belt 21 when it rotates. The guide member 22 is made of an insulating material that does not hinder passage of magnetic flux, and is made of a material that can withstand a high load, such as iron, stainless steel, and aluminum. In this example, the guide member 22 is an electromagnetic induction heat-generating member, and the guide member 22 is first heated by the electromagnetic induction heating means, and the fixing belt 21 is heated by the heated guide member 22. 21 is indirectly heated by induction heating means. However, as disclosed in Japanese Patent Laid-Open No. 2001-102163, the fixing belt 21 may have an electromagnetic induction heating layer and be directly heated by induction heating means.

An insulating member 27 is arranged between the magnetic core 25 and the exciting coil 26 and the reinforcing member 23 . A good heat conducting member 28 is arranged along the longitudinal direction on the lower surface of the guide member 22 corresponding to the fixing nip portion N. Heat generated by the exciting coil 26 and the magnetic core 25, which are magnetic field generating means, is provided. It is arranged outside the magnetic field so as not to be affected by the magnetic field. The good heat-conducting member 28 has the effect of making the temperature distribution in the longitudinal direction of the fixing nip portion N uniform. The heat is transferred to the member 28, and the heat quantity in the non-sheet-passing portion is transferred to the small-size paper-passing portion by heat conduction in the longitudinal direction of the good heat-conducting member 28. As a result, it is also possible to obtain the effect of reducing power consumption when passing small size paper.

The pressure roller 24 is driven to rotate counterclockwise in the drawing by a drive means M. As shown in FIG. When the pressure roller 24 is driven to rotate, a rotational force acts on the fixing belt 21 due to the frictional force between the pressure roller 24 and the outer surface of the fixing belt 21 at the fixing nip portion N, and the fixing belt 21 is guided at the fixing nip portion N. While sliding in close contact with the member 22, it rotates with the guide member 22 at a peripheral speed substantially corresponding to the peripheral speed of the pressure roller 24 in the clockwise direction in the figure. At this time, in order to reduce mutual sliding frictional force between the good heat conductive member 28 and the fixing belt 21 at the fixing nip portion N, lubrication such as heat-resistant grease is applied between the good heat conductive member 28 and the fixing belt 21 at the fixing nip portion N. An agent may be interposed, or the lower surface of the good heat conducting member 28 may be coated with a lubricating member.

Current supply to the excitation coil 26 is controlled based on the result detected by the temperature detection means 29 arranged on the outer surface of the guide member 22, which is the range of the heat generation area by the induction heating means, and the fixing nip portion N reaches a predetermined temperature. The temperature of the fixing belt 21 is adjusted so as to maintain the temperature. A temperature detection unit 29 is a temperature sensor such as a thermistor that detects the temperature of the fixing belt 21 . As the inner surface of the fixing belt 21 slides and rotates on the temperature detecting means 29, the temperature is detected.

A thermoswitch 40, which is a temperature detecting element, is provided at a position facing the heating region of the fixing belt 21 (corresponding to the heat generating region of the guide member 22) to cut off the power supply to the excitation coil 26 during runaway. It is arranged in a non-contact manner.

The fixing device 20 configured as described above operates as follows.
When the pressure roller 24 is rotationally driven and the fixing belt 21 is rotated along with it, the fixing belt 21 is heated at a position facing the induction heating means. Specifically, by passing a high-frequency alternating current through the exciting coil 26, magnetic lines of force are alternately formed around the guide member 22 in two directions, and eddy currents are generated on the surface of the guide member 22, and the guide member 22 itself Joule heat is generated by the electrical resistance of The Joule heat heats the guide member 22 by electromagnetic induction, and the fixing belt 21 is heated by the heated guide member 22 to be adjusted to a predetermined temperature. On the other hand, the paper P discharged from the paper feed tray 10 is introduced between the fixing belt 21 and the pressure roller 24 of the fixing nip portion N with the image surface facing upward, that is, facing the fixing belt surface, and is introduced into the fixing nip. At the portion N, the image surface comes into close contact with the outer surface of the fixing belt 21 and is nipped and conveyed through the fixing nip portion N together with the fixing belt 21 .

Here, the phenomenon in which the fixing belt 21 slips gradually occurs as a minute slip (micro slip) over time. abnormal rotation) does not occur suddenly. A minute slip appears as an output of the temperature detecting means, but it is short, such as several tens to several hundreds of milliseconds, and the temperature output difference from the normal state is also small (FIG. 3).

However, the frequency of occurrence of the minute slip itself gradually increases according to the number of sheets passed and the usage time (FIG. 4). Therefore, the occurrence of a large slip can be predicted from the frequency of occurrence of this temperature overshoot before the temperature rise caused by such a small slip is detected, and before the slip leads to an abnormal state where the temperature rises rapidly. , to prevent serious anomalies (safety-related anomalies, downtime caused by failures) by notifying the user.

In addition to the slippage, the causes that disturb the detection history of the temperature detection means, especially the temperature drop, include the image pattern, power supply voltage change, paper thickness, paper temperature, belt circumference, relationship between heat source heating cycle and paper entry timing, etc. , due to various factors. Therefore, it is difficult to identify the slip only with the value detected by the temperature detecting means arranged at a position different from the heat generating portion, as in the prior art. As for the integrated value of input electric power, which is also used for that purpose, there is a time lag caused by feeding back the value measured by the temperature detection means to increase the power output, and a time lag caused by the configuration in which the temperature detection means is arranged at a position different from the heat generating part. Therefore, the slip can actually be detected after a certain amount of time has passed since the slip started to occur, and only an abnormal operation in which a normal image output cannot be obtained can be detected.

Of the various factors that affect the temperature output of the temperature detection means, factors other than slip do not change according to the number of sheets passed or the time of use. The frequency of occurrence and the amount of displacement increase as the torque increases due to the increase in the frictional force of the moving parts. In the fixing device according to the present embodiment, the temperature detection means is arranged in the heating area and the temperature of the heating area is directly detected. It can be stopped and damage to members can be prevented.

Next, an operation flow for detecting an increase in minute slip before a large slip as rotation abnormality occurs will be described with reference to FIG. The output of the temperature sensor (temperature detecting means 29) is monitored while the fixing device 20 is rotating (S1). When the sensor reading exceeds the threshold value a (preset specified value) (S2), the value of the detection number counter is incremented by 1 (S3). Accumulate the counter value for N seconds (S4), check whether the counter value exceeds the threshold value b after N seconds (S5/number of times exceeding the specified value per predetermined time), and set the threshold value b (preset specified number of times). If it exceeds, it is determined that there is a rotation abnormality (preliminary rotation abnormality) and an alert is displayed (S6) to notify the user of slip detection and prompt replacement. After that, the detection number counter is reset (S7), and the paper feeding operation is completed (S8). In S5, if the number of times the temperature sensor exceeds the threshold value does not exceed the specified number of times (threshold value b) within the predetermined time (N seconds), the main factor affecting the output of the temperature sensor is other than the small slip. Assume that there is, do not display an alert, and reset the detection counter.

A slip detection flow that can be used together with the slip detection flow of FIG. 5 is shown in FIG. 6 and will be described. While the fixing device 20 is rotating, it monitors and records the output of the temperature sensor (temperature detecting means 29) at regular intervals (S11). When the difference between the previous value and the current value exceeds the threshold value a (S12), that is, when the detected rate of temperature rise per predetermined time exceeds a preset specified value, the paper feeding operation is terminated (S13). An alert is displayed (S14) to notify the user of slip detection and prompt replacement.

Next, instead of the operation flow according to FIG. 5, the question is whether the number of times the threshold value of the temperature sensor is exceeded exceeds a specified number of times during a predetermined time (N seconds), in other words, the number of times the threshold value is exceeded per predetermined time. 7, an operation flow for detecting an increase in minute slips based on whether or not the number of times the temperature sensor exceeds the threshold value per number of sheets passed exceeds a predetermined number of times.

The output of the temperature sensor (temperature detecting means 29) is monitored while the fixing device 20 is rotating (S21). When the sensor reading exceeds the threshold value a (S22), the value of the detection number counter is incremented by 1 (S23). The counter value is accumulated until N sheets are passed (S24), and after the N sheets have been passed, it is checked whether the counter value exceeds the threshold value b (S25), and if the threshold value is exceeded, rotation abnormality (preliminary rotation abnormality). Then, an alert is displayed (S26) to inform the user of the slip detection and prompt replacement. After that, the detection number counter is reset (S27), and the paper feeding operation is finished (S28). In S25, if the number of times the temperature sensor exceeds the threshold value does not exceed the specified number of times (threshold value b) during the predetermined number of sheets (N sheets), the main factor affecting the output of the temperature sensor is other than the small slip. Assume that there is, do not display an alert, and reset the detection counter.

In the operation for detecting an increase in minute slip as described above, even if an alert is displayed, a large slip as rotation abnormality does not immediately occur. Therefore, it is conceivable that even if the alert is displayed, the user will not replace the fixing device unless the image quality clearly deteriorates. Therefore, even if it is determined that the rotation is abnormal and the alert is displayed, if the fixing device is not replaced, and if the preliminary rotation abnormality is recognized again before the number of sheets passed is small, the fixing device is replaced. It is preferable to emphasize the alert display prompting the replacement to prompt the failure avoidance operation. For emphasizing the alert display, for example, flashing of the alert display, change of the color of the alert display, and the like can be considered. An operation flow in that case will be described based on FIG.

The output of the temperature sensor (temperature detecting means 29) is monitored while the fixing device 20 is rotating (S31). When the sensor reading exceeds the threshold value a (S32), the value of the detection number counter is incremented by 1 (S33). The counter value is accumulated until N sheets are passed (S34), and it is checked whether the counter value exceeds the threshold value b after passing the N sheets (S35). It is checked whether or not the number of sheets passed from the determination of abnormal rotation is smaller than a preset threshold value c (S36). The counter is reset (S38).

The operation flow according to FIG. 8 and another operation flow will be described based on FIG. This is done by further recording the number of sheets passed until the next preliminary rotation abnormality is determined after the preliminary rotation abnormality has been determined, and when the recorded value has continuously fallen below the specified value. , to prompt the failure avoidance operation.

The output of the temperature sensor (temperature detecting means 29) is monitored while the fixing device 20 is rotating (S41). When the sensor reading exceeds the threshold value a (S42), the value of the detection number counter is incremented by 1 (S43). The counter value is accumulated until N sheets are passed (S44), and it is checked whether the counter value exceeds the threshold value b after passing the N sheets (S45). It is checked whether or not the number of sheets passed is smaller than a preset threshold value c (S46), and if it is determined to be smaller than the threshold value c, the value of the determination counter is incremented by 1 (S47). When the determination number counter reaches 2 (S48/continuously below the threshold value c), an alert display (emphasized alert display) is performed (S49), and the detection number counter is reset.

Another mode of prompting the failure avoidance operation will be described with reference to FIGS. 10 to 12. FIG. In the first mode, after it is determined that rotation is abnormal, the number of sheets passed until it is determined that rotation is abnormal next time is recorded for a specified number of times, and when the average value of the recorded values falls below the specified value, This is to prompt the failure avoidance operation. The output of the temperature sensor (temperature detecting means 29) is monitored while the fixing device 20 is rotating (S51). When the sensor reading exceeds the threshold value a (S52), the numerical value of the total sheet passing counter is recorded (S53). Then, the number of sheets A between recording intervals is calculated from the previous recording (S54), and when the number of times the sensor reading value exceeds the threshold value a exceeds the specified number of times (S55), the paper feeding operation is finished (S56). The calculated number of sheets A is recorded for a specified number of times, and when the average value is below the threshold value b (S57), an alert display (emphasized alert display) is performed (S58).

In the second mode, after it is determined that rotation is abnormal, the number of sheets passed until it is determined that rotation is abnormal next time is recorded for a specified number of times, and when the median value of the recorded values falls below the specified value, This prompts failure avoidance actions (Fig. 11). The output of the temperature sensor (temperature detecting means 29) is monitored while the fixing device 20 is rotating (S61). When the reading value of the sensor exceeds the threshold value a (S62), the value of the total sheet passing counter is recorded (S63). Then, the number of sheets A between recording intervals is calculated from the previous recording (S64), and when the number of times the sensor reading value exceeds the threshold value a exceeds the specified number of times (S65), the paper feeding operation is finished (S66). The calculated number A of sheets is recorded for a specified number of times, and if the intermediate value is below the threshold value b (S67), an alert display (emphasized alert display) is performed (S68).

Still another aspect is to record the drive time for a specified number of times until the next determination of the rotation abnormality after it is determined that the rotation abnormality has occurred, and when the average value of the recorded values falls below the predetermined value, the failure is avoided. Action prompts are shown in FIG. The output of the temperature sensor (temperature detecting means 29) is monitored while the fixing device 20 is rotating (S71). When the sensor reading exceeds the threshold value a (S72), the value of the driving time counter is recorded (S73). Then, the recording interval drive time A is calculated from the previous recording (S74), and when the number of times the sensor read value exceeds the threshold value a exceeds a specified number of times (S75), the paper feeding operation is terminated (S76). The calculated drive time A is recorded for a specified number of times, and if the average value is below the threshold value b (S77), an alert display (emphasized alert display) is performed (S78).

As described above, small slips gradually increase over time before large slips of the fixing belt that are recognized as abnormal rotation occur. There is little need to start Therefore, it is conceivable to start monitoring and operations related to failure avoidance after the numerical value of the travel distance counter of the fixing device or the number of sheets to be recorded exceeds a predetermined specified value. 12, as shown in FIG. 13, first, it is confirmed whether or not the value of the counter for the number of sheets passed has exceeded a predetermined specified number of sheets (S81). The output of the temperature sensor (temperature detecting means 29) is monitored during the rotation operation (S82). When the sensor reading exceeds the threshold value a (S83), the value of the driving time counter is recorded (S84). Then, the recording interval driving time A is calculated from the previous recording (S85), and when the number of times the sensor read value exceeds the threshold value a exceeds the specified number of times (S86), the paper feeding operation is terminated (S87). The calculated driving time A is recorded for a prescribed number of times, and when the average value is below the threshold value b (S88), an alert display (emphasized alert display) is performed (S89).

In the case of starting monitoring and operation related to failure avoidance when the record of the number of sheets passed (or the traveling distance counter of the fixing device) exceeds a predetermined value, the number of sheets passed and the driving time for the specified number of times (2 times or more) to encourage failure avoidance operations, and can also be applied to modes (FIGS. 4 to 8) in which recording is not performed for a specified number of times.

It is possible to use the "emphasized alert display" to prompt the failure avoidance action as the "near-end notification to the user". Also, instead of "alert display" or "emphasized alert display", "machine stop" may be used at that stage to ensure failure avoidance.

20 fixing device 21 fixing belt (fixing member)
22 guide member 24 pressure roller (pressure rotating body)
29 temperature detection means (temperature sensor)

JP-A-2001-102163

Claims (8)

a heating means, a fixing member that is heated and rotated by the heating means, a pressing rotary member that presses against the fixing member to form a fixing nip portion, and is disposed within a heat generating area of the heating means. A fixing device comprising a temperature detection means, wherein the rotation abnormality is determined when the number of times per predetermined time that the value detected by the temperature detection means exceeds a preset specified value exceeds the preset specified number of times. , fuser. 2. The fixing device according to claim 1, wherein rotation abnormality is also determined when a rate of temperature increase per predetermined time detected by said temperature detecting means exceeds a preset specified value. a heating means, a fixing member that is heated and rotated by the heating means, a pressing rotary member that presses against the fixing member to form a fixing nip portion, and is disposed within a heat generating area of the heating means. A fixing device comprising a temperature detection means, wherein a rotation abnormality occurs when the number of times a value detected by the temperature detection means exceeds a preset specified value per sheet passing exceeds a preset specified number of times. The fixing device determines that. 4. The fixing device according to claim 3, wherein the failure avoidance operation is urged when the number of sheets passed until the rotation abnormality is determined next time after the rotation abnormality is determined falls below a preset value. A claim characterized by recording the number of sheets passed until the next determination of rotation abnormality after it is determined that rotation abnormality has occurred, and prompting failure avoidance actions when the recorded value continuously falls below a specified value. Item 4. The fixing device according to item 3. 6. The fixing device according to claim 4, wherein the urging of the failure avoidance operation is a near-end notification to the user. 7. The fixing device according to any one of claims 1 to 6, wherein the machine is stopped when it is determined that the rotation is abnormal or instead of prompting the failure avoidance operation. An image forming apparatus comprising the fixing device according to any one of claims 1 to 7.

Images