JP6773005B2 - Image forming device - Google Patents

Description

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

The electrophotographic image forming apparatus is mainly composed of a photoconductor drum unit, a developing apparatus, a transfer apparatus, and a fixing apparatus. Since the above components deteriorate with the use of the image forming apparatus, they are often treated as consumables in the apparatus design.

The fixing device is a component for fixing the toner on the medium, and includes a heating member, a pressure member, and the like. An example of the above-mentioned deterioration is a decrease in roller hardness of the pressure member. The pressurizing member is deteriorated by being repeatedly heated by the heating member to expand, then cooled and contracted. Since the deterioration of the fixing device depends on the heating time, the standby time, the storage state, and the like, it is difficult to predict based on the number of simple media prints (number of fixing processes).

Therefore, a configuration has been proposed in which a new sensor specialized for diagnosing deterioration of members is provided. For example, in the image forming apparatus described in Patent Document 1, deterioration of the fixing roller is diagnosed by capturing a decrease in the reflected brightness from a thin film provided on the surface of the fixing roller by using an optical sensor. Further, in the image forming apparatus described in Patent Document 2, a failure or deterioration is diagnosed by detecting a scattered reflection component and acquiring information on a transport state of printing paper by using a photodetector array. There is.

Japanese Unexamined Patent Publication No. 2003-255737 Japanese Unexamined Patent Publication No. 2005-41623

However, in the technique disclosed in Patent Documents 1 and 2 above, in which a newly provided sensor is provided to acquire parameters related to deterioration of the fixing device, the newly provided sensor may be used infrequently. As a result, the cost-effectiveness of deterioration diagnosis may be low.

In consideration of the above circumstances, it is an object of the present invention to cost-effectively and appropriately calculate parameters related to deterioration of the fixing device.

In order to achieve the above object, the image forming apparatus of the present invention forms a pressure region by pressing and contacting a heating member that heats the toner on the medium while rotating and the heating member while rotating, and pressurizes the power. A pressurizing member that pressurizes the toner on the medium passing through the region, a heating device that heats the heating member by an input power, a temperature detection device that detects the temperature of the heating member, and a cycle in which the input power changes. A power control unit that periodically changes the input power based on each of the change frequencies corresponding to, a gain calculation unit that calculates a gain that is the ratio of the temperature to the input power for each of the plurality of the change frequencies, and a gain calculation unit. A control device having a resonance parameter calculation unit for calculating a resonance parameter reflecting deterioration of the pressurizing member based on the plurality of gains is provided.

Preferably, the control device further includes a drive speed correction unit that corrects the drive speed of the drive device that drives the pressurizing member so as to compensate for the transport speed of the medium that has decreased due to the deterioration of the pressurizing member. Be prepared.

Preferably, the control device further includes an alert unit that generates an alert when the degree of deterioration of the pressurizing member indicated by the resonance parameter is equal to or greater than a threshold value.

Preferably, the resonance parameter calculation unit calculates the resonance parameter for each predetermined number of prints.

Preferably, the resonance parameter calculation unit calculates the resonance parameter based on an instruction from the operator.

According to the present invention, it is possible to calculate the parameters related to the deterioration of the fixing device with an inexpensive and appropriate configuration.

It is a schematic (front view) which shows the image forming apparatus which concerns on one Embodiment of this invention. It is sectional drawing which shows the fixing device which concerns on one Embodiment of this invention. It is a graph which shows an example of the time characteristic of input power change and temperature change which concerns on one Embodiment of this invention. It is a graph which shows an example of the time characteristic of input power change and temperature change which concerns on one Embodiment of this invention. It is a graph which shows an example of the time characteristic of input power change and temperature change which concerns on one Embodiment of this invention. It is a frequency characteristic diagram which shows the relationship between gain and frequency which concerns on one Embodiment of this invention. It is a figure which shows the electrical structure of the control device which concerns on one Embodiment of this invention. It is a flowchart of deterioration diagnosis processing and deterioration coping processing which concerns on one Embodiment of this invention.

1. 1. Overall Configuration of Image Forming Device The overall configuration of the image forming apparatus 1 according to the embodiment of the present invention will be described with reference to FIG. The image forming apparatus 1 is, for example, a multifunction device having a printing function, a copying function, a fax function, and the like.

Hereinafter, for convenience of explanation, the front side of the paper surface of FIG. 1 is referred to as the front side of the image forming apparatus 1. Further, in each of the following figures, "L" indicates "left", "R" indicates "right", "U" indicates "upper", and "D" indicates "lower".

FIG. 1 is a schematic view (front view) showing the image forming apparatus 1. In the following description, the "transport direction" refers to the direction in which the sheet S (medium) is conveyed. In addition, "upstream" and "downstream" and similar terms refer to "upstream" and "downstream" in the transport direction of the sheet S and similar concepts.

The image forming apparatus 1 includes a substantially box-shaped apparatus main body 2. A paper feed cassette 3 for accommodating a sheet S such as plain paper is detachably provided at the lower part of the apparatus main body 2, and a paper ejection tray 4 is provided at the upper part of the apparatus main body 2. The sheet S as an example of the medium is not limited to paper, and may be made of resin.

The apparatus main body 2 includes a paper feeding device 5, an image drawing device 6, and a fixing device 7. The paper feed device 5 is provided at the upstream end of the transport path 8 extending from the paper feed cassette 3 to the paper output tray 4. The image forming device 6 is provided in the middle portion of the transport path 8, and the fixing device 7 is provided on the downstream side of the transport path 8.

The image forming apparatus 6 includes a toner container 10, a drum unit 11, and an optical scanning apparatus 12. The toner container 10 contains, for example, black toner (developer). The drum unit 11 includes a photoconductor drum 13 (image carrier), a charging device 14, a developing device 15, and a transfer roller 16. The transfer roller 16 contacts the photoconductor drum 13 from below to form a transfer nip. The toner may be a two-component developer in which toner and a carrier are mixed, or may be a one-component developer composed of magnetic toner.

Further, the device main body 2 includes a control device 100 that controls each device. Details of the control device 100 will be described later. Further, the image forming apparatus 1 is provided with a display unit 102 on the upper surface (or side surface) of the apparatus main body 2 for displaying the state of the image forming apparatus 1. The display unit 102 is composed of a touch panel, a display, or the like, and displays, for example, a replacement time of a member included in the fixing device 7. The display unit 102 may include operation keys for operating the image forming apparatus 1, such as a start key, a stop / clear key, and a numeric keypad. The display unit 102 may be separately provided outside the image forming apparatus 1. For example, the display unit 102 may be configured as a display device such as an external display connected to the image forming device 1.

2. Outline of processing of the image forming apparatus Next, the image forming processing by the image forming apparatus 1 having the above-described configuration will be schematically described. The image forming apparatus 1 starts the image forming process when the image data is input from an external computer or the like and the printing start is instructed.

Under the control of the control device 100, the image forming process is executed as follows. First, the charging device 14 charges the surface of the photoconductor drum 13. The optical scanning device 12 emits scanning light corresponding to the image data to form an electrostatic latent image on the surface of the photoconductor drum 13. The developing device 15 develops an electrostatic latent image carried on the photoconductor drum 13 into a toner image by using the toner supplied from the toner container 10. The sheet S is sent out from the paper feeding device 5 to the transport path 8 by the paper feeding device 5, and the toner image is transferred onto the sheet S passing through the transfer nip on the photoconductor drum 13. The fixing device 7 fixes the toner image on the sheet S, and the sheet S on which the toner image is fixed is discharged to the paper output tray 4.

3. 3. Fixing device Next, the configuration and operation of the fixing device 7 will be described with reference to FIG. FIG. 2 is a cross-sectional view of the fixing device 7. As shown in FIG. 2, the fixing device 7 includes a housing 20, a heating member 21, a pressurizing member 22, a heat generating unit 23 (heating device), and a temperature sensor 24 (temperature detecting device).

The housing 20 has a substantially rectangular parallelepiped structure long in the front-rear direction, and includes a case 20A supported inside the device main body 2. Openings for passing the sheet S are formed on both the left and right sides of the case 20A. The right side opening of the case 20A is provided with an entry guide 31 for guiding the sheet S to the fixing nip N (pressurizing region) which is a contact portion between the fixing belt 21A included in the heating member 21 and the pressing member 22. There is. A transport roller pair 32 for feeding the sheet S to the downstream side is provided in the left side opening of the case 20A.

The heating member 21 includes an endless fixing belt 21A formed in a substantially cylindrical shape long in the front-rear direction, and a pair of caps 21B attached to both ends in the axial direction of the fixing belt 21A. The base layer of the fixing belt 21A is made of a synthetic resin material having heat resistance and elasticity such as a polyimide resin. An elastic layer such as silicone rubber is formed on the outer peripheral surface of the base layer, and a surface release layer such as fluororesin (PFA) is formed on the outer peripheral surface of the elastic layer. A pressing structure 26 is provided inside (inside) the fixing belt 21A. The pressing structure 26 includes a supporting member 26A and a pressing member 26C. The support member 26A is formed of, for example, a metal material in a substantially rectangular tubular shape that is long in the front-rear direction. The pressing member 26C is a thick plate-shaped member made of heat-resistant resin fixed to the lower surface of the supporting member 26A, and has a function of receiving the fixing belt 21A pressed against the pressing member 22. Inside the fixing belt 21A, a belt guide 27 for maintaining the shape of the fixing belt 21A is provided. The belt guide 27 is made of an alloy having a large magnetic permeability and is heated by the heat generating unit 23.

The pressurizing member 22 is formed in a substantially cylindrical shape that is long in the front-rear direction. The pressurizing member 22 is made of a metal core metal 22A, an elastic layer 22B such as silicone rubber laminated on the outer peripheral surface of the core metal 22A, and a fluororesin (PFA) laminated on the outer peripheral surface of the elastic layer 22B. A surface release layer 22C is provided. A drive motor 28 (drive device) is connected to the core metal 22A, and the pressurizing member 22 is rotationally driven by the drive motor 28. The elastic layer 22B serves as the main pressure source for the heating member 21. The heating member 21 is driven to rotate by the rotation transmitted from the pressurizing member 22. The pressurizing member 22 presses against the heating member 21 (fixing belt 21A) while rotating to form a fixing nip N, and pressurizes the toner on the sheet S passing through the fixing nip N.

The heat generating unit 23 is arranged above the fixing belt 21A with a gap in between. The heat generating unit 23 includes a unit case 23A and an IH coil 23B. The unit case 23A is formed in a substantially semi-cylindrical shape that is long in the front-rear direction along the upper outer surface of the fixing belt 21A. The IH coil 23B is provided inside the unit case 23A. A magnetic field is generated by applying a high-frequency current to the IH coil 23B, and the belt guide 27 is induced and heated by the magnetic field to locally heat the upper side of the fixing belt 21A. That is, the heat generating unit 23 heats the pressurizing member 22 (fixing belt 21A) by the input power.

As described above, the heating member 21 is driven and rotated by the pressurizing member 22, and is heated by the heat generating unit 23. As a result, the heating member 21 heats the toner on the sheet S while rotating.

The temperature sensor 24 contacts the fixing belt 21A from the inside and detects the temperature of the heating member 21 (fixing belt 21A). The temperature sensor 24 includes a thermistor, which is a semiconductor element whose resistance changes according to the temperature, and transmits a detection signal D corresponding to the detection temperature of the heating member 21 to the control device 100. The temperature sensor 24 may be in contact with the fixing belt 21A from the outside, or may be a non-contact type temperature sensor that detects the temperature apart from the fixing belt 21A.

The heat generating unit 23 (IH coil 23B), the temperature sensor 24, the drive motor 28, and the like described above are electrically connected to the control device 100 via various drive circuits. The heat generating unit 23 (heating device) and the temperature sensor 24 (temperature detecting device) may be provided separately from the fixing device 7.

4. Deterioration of Fixing Device (Pressurizing Member) The pressurizing member 22 included in the fixing device 7 deteriorates as the image forming process is repeatedly executed by the image forming device 1. More specifically, it is as follows. When the fixing process is performed in the fixing device 7, the elastic layer 22B and the surface release layer 22C of the pressing member 22 are heated by the heating member 21 to expand, and then cooled by natural cooling or the like to shrink. By repeating the above expansion and contraction, the elastic layer 22B and the surface release layer 22C deteriorate.

As the deterioration progresses, the hardness of the pressurizing member 22 at the time of pressurization decreases (that is, the pressurizing member 22 softens), and the amount of biting into the heating member 21 also decreases. As a result, the medium transport speed during the fixing process changes, increasing the possibility of transport wrinkles. As described above, since the deterioration of the pressure member 22 depends on a plurality of conditions such as heating time, standby time, and storage state, it is difficult to predict based on the number of simple media prints (number of fixing processes). ..

5. Principle of Deterioration Diagnosis When the pressure member 22 deteriorates and its hardness decreases, the outer diameter of the pressure member 22 decreases. Therefore, under the condition of constant angular velocity, the linear velocity (the speed at which the point on the outer circumference advances, the peripheral velocity). Decreases. When the linear velocity of the pressurizing member 22 decreases, the linear velocity of the heating member 21 (fixing belt 21A) driven by the pressurizing member 22 also decreases. Generally, in a rotating body, under a condition where the angular velocity is constant, the rotation period (time required for one rotation) increases as the linear velocity of points on the outer circumference decreases. Therefore, as the pressurizing member 22 deteriorates, the linear velocity of the heating member 21 decreases and its rotation cycle increases.

Based on the above findings, if an increase in the rotation cycle (or a decrease in linear velocity) of the heating member 21 can be detected in the fixing device 7 as in the present embodiment, the deterioration state of the pressurizing member 22 can be diagnosed. As described above, it is not preferable to provide a new sensor in the image forming apparatus 1 from the viewpoint of cost effectiveness. Therefore, it will be examined below to capture the fluctuation of the rotation cycle of the heating member 21 without adding the sensor.

Here, it is considered that the input power input to the heat generating unit 23 is periodically changed. As described above, the heat generating unit 23 (IH coil 23B) heats the heating member 21 (fixing belt 21A) via the belt guide 27 by applying electric power. Therefore, when the power input to the heat generating unit 23 changes periodically, the heat energy transmitted to the heating member 21 also changes periodically, and a periodic temperature change occurs in the heating member 21. The relationship between the change in input power and the change in temperature will be described below.

3A to 3C are graphs illustrating the time characteristics of input power change and temperature change. The vertical axis of the graph on the left side of each figure shows the magnitude of the input power P applied to the heat generating unit 23, and the vertical axis of the graph on the right side of each figure shows the temperature T of the heating member 21 detected by the temperature sensor 24. The horizontal axis of each graph indicates time t. In each figure, the power input P to the heat generating unit 23 periodically increases or decreases at a specific frequency F (graphs on the left side), and the temperature T of the heating member 21 also periodically increases or decreases at the specific frequency F (each graph on the left). Each graph on the right). More specifically, the frequencies (change frequencies F) corresponding to the periods in which the input power P changes in FIGS. 3A to 3C are 1 Hz, 2 Hz, and 4 Hz, respectively. The temperature T in FIGS. 3A to 3C also changes at 1 Hz, 2 Hz, and 4 Hz, respectively.

On the other hand, the range of change of the input power P in FIGS. 3A to 3C is constant (upper limit 300W-lower limit 100W = 200W). However, as shown in FIGS. 3A to 3C, the change width of the detection temperature T becomes smaller as the change frequency F in which the input power P changes increases. The above phenomenon is caused by the existence of a time lag until the change in the power input P to the heat generating unit 23 appears as the change in the temperature T of the heating member 21. As the cycle of change of the input power P becomes shorter (the change frequency F increases), the change of the temperature T of the heating member 21 becomes difficult to follow the power change due to the time lag, so that the width of the temperature change becomes smaller.

FIG. 4 is a graph (frequency characteristic diagram) showing the frequency characteristics of the change in the input power P and the change in the temperature T described above. The horizontal axis of the graph shows the change frequency F of the input power P, and the vertical axis shows the gain G (temperature T of the heating member 21 / power input P to the heat generating unit 23). Briefly, as described above, as the change frequency F of the input power to the heating unit 23, which is the heating device, increases, the width of the temperature change of the heating member 21 becomes smaller, so that the gain G decreases.

However, in FIG. 4, characteristic changes not explained by the above schematic behavior are observed. That is, while the gain G gradually decreases as the change frequency F rises, the gain G shows a maximum value at a specific change frequency F. This phenomenon is caused by the following factors.

As described above, the heating member 21 is driven to rotate by the pressurizing member 22, and the upper side thereof is locally heated by the heat generating unit 23. In other words, the heated portion on the heating member 21 changes with time according to the driven rotation. Further, as described above, when the power input P to the heat generating unit 23 is changed periodically, the temperature T of the heating member 21 also changes periodically.

Here, when the rotation cycle of the heating member 21 and the change cycle of the input power P to the heat generation unit 23 (that is, the arrival cycle of the power peak) match, a specific heated portion on the heating member 21 receives the input power. It will be repeatedly heated by the peak portion of P. For example, if the rotation cycle of the heating member 21 is 0.5 seconds (rotation frequency R = 2 Hz) and the change cycle of the input power P is 0.5 seconds (change frequency F = 2 Hz), the heating member The specific heated portion on 21 is repeatedly heated by the input power P every 0.5 seconds.

As understood from the above contents, when the change cycle of the input power P matches the rotation cycle of the heating member 21 (in other words, when the change frequency F of the input power P matches the rotation frequency R of the heating member 21). Compared to the case where this is not the case, the temperature T (molecule of gain G) of a specific heated portion becomes higher. In other words, when the rotation of the heating member 21 and the change in the input power P resonate, the temperature T of the specific heated portion becomes higher. As a result, the gain G takes a maximum value at a point (resonance point) where the rotation frequency R of the heating member 21 becomes equal to the change frequency F. For future reference, the frequency at the resonance point (rotation frequency R = change frequency F) is referred to as resonance frequency RF.

The resonance frequency RF is substantially equal to the rotation frequency of the heating member 21. Since the reciprocal of the frequency is the period, the reciprocal of the resonance frequency RF (resonance period RP) is substantially equal to the rotation period of the heating member 21. Therefore, if the resonance frequency RF is obtained, the rotation period of the heating member 21 can be obtained.

As described above (particularly as shown in FIG. 4), a new sensor can be obtained by changing the change period (change frequency F) of the input power P to the heat generating unit 23 over a plurality of values to obtain the resonance frequency RF. It is possible to capture the fluctuation of the rotation cycle of the heating member 21 without adding it.

As described above, as the pressurizing member 22 deteriorates, the outer diameter of the pressurizing member 22 decreases, so that the linear velocity of the heating member 21 decreases and the rotation cycle increases. Since the rotation frequency decreases as the rotation cycle increases, deterioration of the pressurizing member 22 can be diagnosed by detecting a decrease in the resonance frequency RF (= rotation frequency R). In other words, the resonance frequency RF is a value that reflects the deterioration of the pressurizing member 22.

Further, as described above, as the pressurizing member 22 deteriorates, the linear velocity decreases, and eventually the conveying speed of the sheet S decreases. Then, when the progress of deterioration becomes remarkable, the possibility that the quality of the printed image deteriorates and the rubber member such as the elastic layer 22B breaks increases. Therefore, in order to realize stable operation of the fixing device 7, the drive speed is corrected so as to compensate for the reduced transport speed if the deterioration progresses lightly, and if the deterioration progresses significantly, the user is notified. It is preferable to raise an alert.

The configuration and operation of the control device 100 used for diagnosing the deteriorated state of the pressurizing member 22 and dealing with the deterioration will be specifically described below.

6. Control device FIG. 5 is a diagram showing an electrical configuration of the control device 100. The control device 100 is composed of a CPU and the like, and is connected to a storage device 104 including a ROM, a RAM, and the like. Further, the control device 100 is connected to each part of the image forming device 1 such as the fixing device 7 (particularly, the heat generating unit 23, the temperature sensor 24, and the drive motor 28) and the display unit 102. The control device 100 controls each unit connected to the control device 100 based on the control program and the control data stored in the storage device 104. More specifically, it is as follows.

The control device 100 includes a power control unit 110, a gain calculation unit 112, a resonance parameter calculation unit 114, a drive speed correction unit 116, and an alert unit 118. The power control unit 110, the gain calculation unit 112, and the resonance parameter calculation unit 114 are components of the deterioration diagnosis unit 120, and the drive speed correction unit 116 and the alert unit 118 are components of the deterioration coping unit 122.

The power control unit 110 controls so that the input power P applied to the heat generating unit 23 (heating device) changes periodically based on each of the plurality of change frequencies F. The values of the plurality of change frequencies F are stored in the storage device 104. The gain calculation unit 112 calculates the gain G, which is the ratio (T / P) of the detected temperature T of the temperature sensor 24 to the power input P to the heat generating unit 23 for each of the plurality of change frequencies F. The resonance parameter calculation unit 114 calculates the resonance frequency RF, which is a value reflecting the deterioration of the pressurizing member 22, based on the plurality of gains G calculated by the gain calculation unit 112. The drive speed correction unit 116 corrects the drive speed of the drive motor 28 based on the calculated resonance frequency RF so as to compensate for the transfer speed of the seat S that has decreased due to the deterioration of the pressurizing member 22. The alert unit 118 generates an alert when the degree of deterioration of the pressurizing member 22 exceeds the threshold value.

FIG. 6 is a flowchart of deterioration diagnosis processing and deterioration coping processing by the control device 100. When the deterioration diagnosis process is started, the deterioration diagnosis unit 120 selects one from the plurality of change frequencies F stored in the storage device 104 (step S50). In selecting the change frequency F, the deterioration diagnosis unit 120 may select in ascending order of frequency, in descending order of frequency, or randomly select frequencies that have not yet been selected. Alternatively, the frequencies may be selected in a predetermined order stored in the storage device 104.

Next, the power control unit 110 executes control so that the input power P to the heat generating unit 23 changes according to the change frequency F (that is, the change cycle 1 / F) selected by the deterioration diagnosis unit 120 (step S52). ..

In a state where the input power P to the heating unit 23 changes periodically according to the change frequency F, the gain calculation unit 112 receives the detection signal D from the temperature sensor 24 and acquires the detection temperature T of the heating member 21. Then, the gain (T / P), which is the ratio of the detected temperature T to the input power P, is calculated (step S54).

When the calculation of the gain G corresponding to the current change frequency F in step S54 is completed, the deterioration diagnosis unit 120 has completed the calculation of the gain G for all of the plurality of change frequencies F for which the gain is calculated. (Step S56). If the calculation is not completed (step S56: NO), the deterioration diagnosis unit 120 executes steps S50 to S54 again. On the other hand, when the calculation is completed (step S56: YES), the deterioration diagnosis unit 120 advances the process to step S58.

The resonance parameter calculation unit 114 calculates the resonance frequency RF based on the plurality of gains G (step S58). More specifically, the resonance parameter calculation unit 114 specifies the maximum value of the gain G based on the calculated plurality of gains G, and stores the change frequency F corresponding to the specified maximum value as the resonance frequency RF. Store in 104.

When the deterioration diagnosis process of steps S50 to S58 is completed, the deterioration coping unit 122 executes the deterioration coping process. When the resonance frequency RF calculated in step S58 exceeds the threshold value Th (step S60: YES), the deterioration coping unit 122 can deal with the deterioration of the pressurizing member 22 by correction, and thus performs the correction processing in step S62. move on. On the other hand, when the resonance frequency RF is equal to or less than the threshold value Th (step S60: NO), the pressure member 22 is significantly deteriorated, so the process proceeds to the alert process in step S64.

In step S60, "the resonance frequency RF exceeds the threshold value Th" corresponds to "the degree of deterioration of the pressure member 22 is below the threshold value (the pressure member 22 has not reached the end of its life)". "The resonance frequency RF is equal to or less than the threshold value Th" corresponds to "the degree of deterioration of the pressurizing member 22 is equal to or greater than the threshold value (the pressurizing member 22 has reached the end of its life)".

In step S62, the drive speed correction unit 116 corrects the drive speed of the drive motor 28 (drive device) so as to compensate for the transfer speed of the seat S that has decreased due to the deterioration of the pressurizing member 22. More specifically, the drive speed correction unit 116 of the drive motor 28 so that the resonance frequency RF approaches the value at the start of operation of the fixing device 7 (more preferably, the value at the start of operation). Control the drive speed. By the above control, the linear velocity of the pressurizing member 22 approaches the value at the start of operation of the fixing device 7 (more preferably, it becomes the value at the start of operation).

In step S64, the alert unit 118 generates an alert. More specifically, the alert unit 118 transmits an alert signal to the display unit 102 that supports the display of a message indicating that the pressurizing member 22 has reached the replacement time. The display unit 102 displays a message indicating the above alert on the display. Further, the alert unit 118 may transmit an alert signal to a maintenance system existing on the network to which the image forming apparatus 1 is connected, instead of or in addition to transmitting the signal to the display unit 102. Good.

The above deterioration diagnosis process and deterioration coping process may be executed in conjunction with the calibration process executed every time a predetermined number of sheets (for example, 10,000 sheets) are printed, or may be executed in conjunction with the service person (operator). May be executed based on the instruction signal issued by operating the display unit 102.

7. Effect of the present embodiment In the image forming apparatus 1 according to the present embodiment described above, the control device 100 (deterioration diagnosis unit 120) diagnoses the deteriorated state of the pressurizing member 22 of the fixing device 7. That is, the control device 100 calculates the resonance frequency RF, which is a parameter that reflects the deterioration of the pressurizing member 22. With the above configuration, the resonance frequency RF can be calculated without providing a new sensor. Therefore, it is cost-effective for calculation.

Further, according to the image forming apparatus 1 according to the present embodiment, the drive speed correction unit 116 compensates for the transfer speed of the sheet S lowered due to the deterioration of the pressurizing member 22 based on the calculated resonance frequency RF. The drive speed of the drive motor 28 is corrected. According to the above configuration, the influence of deterioration of the pressurizing member 22 (decrease in the linear velocity of the pressurizing member 22) is compensated by the correction of the driving speed, so that a more stable fixing operation is realized.

Further, according to the image forming apparatus 1 according to the present embodiment, the alert unit 118 generates an alert when the degree of deterioration of the pressurizing member 22 indicated by the resonance frequency RF is equal to or greater than the threshold value. According to the above configuration, the life of the pressurizing member 22 appropriately calculated by the resonance frequency RF is transmitted to the user of the image forming apparatus 1.

Further, according to the image forming apparatus 1 according to the present embodiment, the resonance frequency RF is calculated for each predetermined number of printed sheets. According to the above configuration, the resonance frequency RF is calculated periodically and automatically, that is, the degree of deterioration is diagnosed, so that the deterioration of the pressurizing member 22 is suppressed from being overlooked.

Further, according to the image forming apparatus 1 according to the present embodiment, the calculation of the resonance frequency RF is executed based on the instruction from the operator. According to the above configuration, the resonance frequency RF can be calculated, that is, the degree of deterioration can be diagnosed at an arbitrary timing, so that maintenance of deterioration of the pressurizing member 22 becomes easy.

8. Modification Example In the image forming apparatus 1 according to the present embodiment, the resonance frequency RF is calculated as a resonance parameter, but another value, for example, the resonance period RP described above may be calculated as a resonance parameter. That is, an arbitrary value indicating the frequency characteristic of the heating member 21 can be adopted as the resonance parameter. As described above, the deterioration of the pressurizing member 22 can also be diagnosed by detecting the increase in the resonance period RP.

In the image forming apparatus 1 according to the present embodiment, the control device 100 includes both the drive speed correction unit 116 and the alert unit 118, but a configuration in which the control device 100 includes only one of them can be adopted. ..

Further, in the image forming apparatus 1 according to the present embodiment, the heat generating unit 23 is adopted as the heat source, but instead of this, a heat source such as a halogen heater or a carbon heater may be provided inside the fixing belt 21A. Regarding the control of the heat source, the configuration of the present embodiment can be applied as it is.

Further, in the description of the present embodiment, as an example, a case where the present invention is applied to a monochrome printing multifunction device (image forming apparatus 1) is shown, but the present invention is not limited to this, for example, a color printing multifunction device, a single function. The present invention may be applied to a printer, a copier, a facsimile, or the like.

The description of the above embodiment shows one aspect of the image forming apparatus according to the present invention, and the technical scope of the present invention is not limited to the above embodiment.

1 Image forming device 7 Fixing device 21 Heating member 22 Pressurizing member 23 Heat generation unit (heating device)
24 Temperature sensor (Temperature detector)
28 Drive motor (drive device)
100 Control device 102 Display unit 110 Power control unit 112 Gain calculation unit 114 Resonance parameter calculation unit 116 Drive speed correction unit 118 Alert unit N Fixing nip (pressurized area)
S sheet (medium)

Claims (5)

A heating member that heats the toner on the medium while rotating,
A pressure member that presses against the heating member while rotating to form a pressure region and pressurizes the toner on the medium that passes through the pressure region.
A heating device that heats the heating member with the input power,
A temperature detection device that detects the temperature of the heating member, and
A power control unit that periodically changes the input power based on each of the change frequencies corresponding to the cycle in which the input power changes, and a gain that is the ratio of the temperature to the input power for each of the plurality of the change frequencies. An image forming apparatus comprising: a gain calculating unit for calculating a frequency, and a control device having a resonance parameter calculating unit for calculating a resonance parameter reflecting deterioration of the pressurizing member based on the plurality of gains. The control device is
Based on the calculated resonance parameter, a drive speed correction unit that corrects the drive speed of the drive device that drives the pressurizing member so as to compensate for the transport speed of the medium that has decreased due to deterioration of the pressurizing member. The image forming apparatus according to claim 1, further comprising. The control device is
The image forming apparatus according to claim 1 or 2, further comprising an alert unit that generates an alert when the degree of deterioration of the pressurizing member indicated by the resonance parameter is equal to or greater than a threshold value. The image forming apparatus according to any one of claims 1 to 3, wherein the resonance parameter calculation unit calculates the resonance parameter for each predetermined number of printed sheets. The image forming apparatus according to any one of claims 1 to 4, wherein the resonance parameter calculation unit executes calculation of the resonance parameter based on an instruction from the operator.

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