JP7003801B2 - Fixing device and image forming device - Google Patents

Description

The present invention relates to a fixing device for fixing a toner image to a recording medium such as recording paper by heat and pressure in an image forming device such as a printer, a copying machine, or a facsimile, and an image forming device equipped with the fixing device.

An image forming apparatus such as a copying machine, a printer, a facsimile, or a multifunction device integrating these has a fixing device for fixing a toner image formed by an electrophotographic method on a recording medium. As the fixing device is used, the parts deteriorate and the rotational torque becomes heavy, which may cause problems such as paper jams. This is one of the causes of life, and usually, before such a state occurs, regular replacement and maintenance are performed with a sufficient number of used sheets. Further, there is known a technique of detecting torque by detecting a current value of a motor that rotates a fixing device.

However, in the conventional method of performing periodical replacement and maintenance with a predetermined number of sheets, the member is often replaced even when the member is still sufficiently usable, which is uneconomical. Further, in the method of obtaining torque information from the fixing drive motor current value, it is necessary to newly add a motor current detection mechanism, which increases the cost. Furthermore, when the motor that rotates the fixing device also drives other parts, it was not possible to determine what torque was increased.

Therefore, in this type of conventional fixing device, there is known a technique of rotating a roller constituting the fixing mechanism to measure the roller temperature and performing life diagnosis from the roller temperature (see, for example, Patent Document 1). ..

In the fixing device described in Patent Document 1, attention is paid to the characteristic that the temperature rise becomes smaller as the deterioration of the elastic layer progresses while the elastic roller is used continuously, and the life of the elastic roller (elastic layer) is determined from the temperature rise value of the surface of the elastic roller. Judgment is made (paragraph 0060).

However, the fixing device described in Patent Document 1 has a so-called roller fixing structure in which paper is sandwiched between a heating roller and a pressure roller and fixed while being conveyed (see paragraph 0044, FIG. 2). Regarding the life diagnosis method, no consideration was given to the life diagnosis of the fixing device adopting a so-called sliding fixing structure in which an endless belt is sandwiched between the pressure roller and the nip component.

In the fixing device that adopts the sliding fixing structure, the heat capacity between the pressure roller and the belt and the heat generation process are different from those between the rollers in the roller fixing structure, so it is not possible to generate heat efficiently due to frictional force, and the rotational torque. Since it is difficult to detect a suitable temperature for estimation, there is a problem that the life cannot be accurately determined from the estimated rotational torque.

The present invention has been made to solve the above problems. The belt for sliding and fixing is efficiently generated by the frictional force with the pressure member, and the torque increase value is estimated from the temperature of the belt at that time. It is an object of the present invention to provide a fixing device and an image forming device that enable accurate life prediction.

In order to solve the above problems, the fixing device according to the present invention has a flexible endless belt, a pressure member provided on the outside of the belt and facing the belt, and the inside of the belt. A nip forming member provided to form a fixing nip between the belt and the pressurizing member, a heat source for heating the belt, a temperature detecting member for detecting the temperature of the belt, a life diagnosis control means, and the like. The life diagnosis control means measures the temperature of the belt due to frictional heat by rotating the pressurizing member and the belt for a predetermined period in a cold state in which heating by the heat source is stopped. It is characterized in that the life is determined and controlled based on the result of raising the temperature.

According to the present invention, the life can be determined by using the temperature detecting member that is always arranged in the fixing device, the configuration change is unnecessary, and the cost increase can be avoided. Compared with the conventional method in which members such as rollers are replaced uniformly with the number of sheets used, it is possible to suppress the disposal of members in a state where they can still be used, and to use them until the functional life is reached. Therefore, in the present invention, the fixing device that efficiently generates heat by the frictional force with the pressurizing member of the belt for sliding fixing and estimates the torque increase value from the temperature of the belt at that time to enable accurate life prediction. And an image forming apparatus can be provided.

It is sectional drawing which shows the structure of the image forming apparatus which comprises the fixing apparatus which concerns on one Embodiment of this invention. It is sectional drawing of the fixing device of the image forming apparatus which concerns on one Embodiment of this invention. It is a figure which shows the control structure of the image forming apparatus which concerns on one Embodiment of this invention. It is a functional block diagram of the life diagnosis control part of the fixing device of the image forming apparatus which concerns on one Embodiment of this invention. It is a graph which showed the relationship between the belt temperature and the unit torque for each rotation drive period at the time of a cold drive in a sliding fixing type fixing unit. It is a flowchart which shows the life diagnosis control operation by the life diagnosis control part of the fixing device of the image forming apparatus which concerns on one Embodiment of this invention. It is a figure which shows the display example of the life notification screen in step S9 of FIG. It is sectional drawing of the fixing device of the image forming apparatus which concerns on other embodiment of this invention.

Next, an embodiment of the fixing device and the image forming device of the present invention will be described with reference to the drawings.

The image forming apparatus 100 shown in FIG. 1 is a tandem color printer in which image forming portions forming a plurality of color images are juxtaposed along the stretching direction of the belt. The present invention is not limited to this method, and can be applied not only to printers but also to copiers, facsimile machines and the like.

As shown in FIG. 1, the image forming apparatus 100 according to the present embodiment is photosensitive as an image carrier capable of forming an image as an image corresponding to each of the colors decomposed into yellow, cyan, magenta, and black. A tandem structure in which body drums 20Y, 20C, 20M, and 20Bk are arranged side by side is adopted.

In the image forming apparatus 100, the visible images formed on the photoconductor drums 20Y, 20C, 20M, and 20Bk can move in the arrow A1 direction while facing the photoconductor drums 20Y, 20C, 20M, and 20Bk. The primary transfer is performed on the intermediate transfer body (hereinafter referred to as a transfer belt) 11 which is. By executing this primary transfer process, images of each color are superimposed and transferred, and then, by executing a secondary transfer process on the recording material S on which a recording sheet or the like is used, batch transfer is performed.

Around each of the photoconductor drums 20Y, 20C, 20M, and 20Bk, a device for performing image forming processing according to the rotation of the photoconductor drums 20Y, 20C, 20M, and 20Bk is arranged. Explaining the photoconductor drum 20Bk that forms a black image as a representative, a charging device 30Bk, a developing device 40Bk, a primary transfer roller 12Bk, and a cleaning device 50Bk that perform image forming processing along the rotation direction of the photoconductor drum 20Bk are arranged. ing. The optical writing device 8 is used for writing using the writing light Lb performed after charging.

In the superimposed transfer to the transfer belt 11, the visible images formed on the photoconductor drums 20Y, 20C, 20M, and 20Bk are superimposed and transferred to the same position on the transfer belt 11 in the process of moving the transfer belt 11 in the A1 direction. Will be done. For this purpose, the transfer is performed in the A1 direction by applying a voltage by the primary transfer rollers 12Y, 12C, 12M, 12Bk arranged to face the photoconductor drums 20Y, 20C, 20M, 20Bk with the transfer belt 11 interposed therebetween. The timing is staggered from the upstream side to the downstream side.

The photoconductor drums 20Y, 20C, 20M, and 20Bk are arranged in this order from the upstream side in the A1 direction. Each photoconductor drum 20Y, 20C, 20M, 20Bk is provided in an image station for forming yellow, cyan, magenta, and black images, respectively.

The image forming apparatus 100 is arranged so as to face the four image stations that perform image forming processing for each color and above each of the photoconductor drums 20Y, 20C, 20M, and 20Bk, and the transfer belt 11 and the primary transfer roller 12Y. , 12C, 12M, 12Bk; It has a belt cleaning device 13 for cleaning the transfer belt 11 provided, and an optical writing device 8 disposed below the four image stations so as to face each other.

The optical writing device 8 is equipped with a semiconductor laser as a light source, a coupling lens, an fθ lens, a toroidal lens, a folding mirror, a rotating multifaceted mirror as a polarizing means, and the like. The optical writing device 8 emits writing light Lb corresponding to each color for each of the photoconductor drums 20Y, 20C, 20M, and 20Bk to form an electrostatic latent image on the photoconductor drums 20Y, 20C, 20M, and 20Bk. It is configured as. In FIG. 1, the writing light Lb is designated only for the image station of the black image for convenience, but the same applies to the other image stations.

The image forming apparatus 100 is provided with a sheet feeding device 61 as a paper feed cassette loaded with a recording material S conveyed toward between the photoconductor drums 20Y, 20C, 20M, 20Bk and the transfer belt 11. There is. Further, the recording material S conveyed from the sheet feeding device 61 is directed toward the transfer portion between each photoconductor drum and the transfer belt 11 at a predetermined timing in accordance with the formation timing of the toner image by the image station. A pair of resist rollers 4 to be fed are provided. Further, a sensor for detecting that the tip of the recording material S has reached the resist roller pair 4 is provided.

Further, the image forming apparatus 100 includes a fixing device 200 as a roller fixing type fixing unit for fixing the toner image on the recording material S on which the toner image is transferred, and the fixing recording material S on the image forming apparatus 100. A discharge roller 7 for discharging to the outside of the main body is provided. Further, on the upper part of the main body of the image forming apparatus 100, a paper ejection tray 17 for loading the recording material S ejected to the outside of the main body of the image forming apparatus 100 by the ejection roller 7 is provided. Further, on the lower side of the output tray 17, toner bottles 9Y, 9C, 9M, and 9Bk filled with toners of each color of yellow, cyan, magenta, and black are provided.

The transfer belt unit 10 has a drive roller 72 and a driven roller 73 around which the transfer belt 11 is hung, in addition to the transfer belt 11, the primary transfer rollers 12Y, 12C, 12M, and 12Bk.

The driven roller 73 also has a function as a tension urging means for the transfer belt 11. Therefore, the driven roller 73 is provided with a urging means using a spring or the like. The transfer device 71 is composed of such a transfer belt unit 10, primary transfer rollers 12Y, 12C, 12M, 12Bk, a secondary transfer roller 5, and a belt cleaning device 13.

The sheet feeding device 61 is arranged in the lower part of the main body of the image forming apparatus 100, and has a feeding roller 3 that abuts on the upper surface of the uppermost recording material S. The feeding roller 3 is rotationally driven counterclockwise in the drawing, so that the uppermost recording material S is fed toward the resist roller pair 4.

Although not shown in detail, the belt cleaning device 13 provided in the transfer device 71 has a cleaning brush and a cleaning blade arranged so as to face and abut against the transfer belt 11. The belt cleaning device 13 cleans the transfer belt 11 by scraping and removing foreign substances such as residual toner on the transfer belt 11 with a cleaning brush and a cleaning blade.

The belt cleaning device 13 also has a discharging means for carrying out and disposing of the residual toner removed from the transfer belt 11.

The image forming apparatus 100 includes, for example, an operation unit 310 on the upper part of the main body. The operation unit 310 has a touch panel, various keys, and the like, and by operating these tools, the user can input various commands related to, for example, selection of a desired function, various settings related to the function, and the like. ..

In the image forming apparatus 100, for example, a copy function, a copy size, and a number of sheets are selected by the user using the operation unit 310, and when a copy start operation is performed, the sheet feeding device 61 corresponding to the selected size is fed. While feeding the recording material S from the cassette, the electrophotographic process control is executed, and the multicolor superimposed toner image formed by the electrophotographic process is transferred (primary transfer) to the transfer belt 11 and further transferred to the recording material S. The image forming process (secondary transfer) is repeatedly executed for the number of printed sheets. When the recording material S to which the toner image is transferred in this image forming process is then passed through the fixing device 200, the toner image is fixed on the upper surface by heat and pressure by the fixing device 200, and the toner image is discharged to the paper ejection tray 17. Will be done.

Next, a schematic configuration of the fixing device 200 according to the present embodiment will be described with reference to FIG.

As shown in FIG. 2, the fixing device 200 is provided on the fixing belt 201, which is a rotatable fixing member and is made of a flexible endless belt, and is provided on the outside of the fixing belt 201 and faces the fixing belt 201. It has a pressurizing roller 203 as a pressurizing member that is arranged and rotatable, and the fixing belt 201 is directly heated by radiant heat from the inner peripheral side by the halogen heaters 202A and 202B as a plurality of heat sources. The fixing belt 201 and the pressure roller 203 correspond to the belt and the pressure member of the present invention, respectively.

At this time, in the fixing belt 201 of FIG. 2, there is a nip forming member 206 that forms a fixing nip between the fixing belt 201 and the pressurizing roller 203, and the inner surface of the fixing belt 201 and the heat transfer assisting member 216. It is designed to slide indirectly via. The toner image on the recording material S is fixed by heating and pressurizing in the fixing nip portion (hereinafter, nip portion) N. As described above, the pressure roller 203 is provided so as to face the fixing belt 201 at the arrangement position of the nip forming member 206 provided inside the fixing belt 201.

In FIG. 2, the shape of the heat transfer aid member 216 is flat, but it may be concave or other. In the case of the concave nip portion N, the discharge direction of the tip of the recording material is closer to the pressure roller 203, and the separability is improved, so that the occurrence of jam is suppressed.

Inside the fixing belt 201, a nip forming member 206 made of a metal plate arranged facing the pressure roller 203 and an end heater 226 as an end heat source integrally provided at both ends of the nip forming member 206. A stay that holds the nip forming member 206, the heat transfer assisting member 216 that covers the surface of the fixing belt 201 of the end heater 226 facing the inner surface, and the nip forming member 206 against the pressure from the pressurizing roller 203. It has a member 207.

The nip forming member 206, the heat transfer assisting member 216, and the stay member 207 all have a length extending in the axial direction (hereinafter, referred to as “longitudinal direction”) of the fixing belt 201.

The heat transfer assist member 216 is provided to prevent the heat of the end heater 226 from staying locally and to positively transfer the heat in the longitudinal direction to reduce the temperature non-uniformity in the longitudinal direction. .. Therefore, it is desirable that the heat transfer assist member 216 is a material capable of heat transfer in a short time, and it is desirable that the member is a member such as copper, aluminum, or silver having high thermal conductivity. Considering cost, availability, thermal conductivity characteristics, and processability comprehensively, it is most desirable to use copper.

In the present embodiment, the surface of the heat transfer aid member 216 facing the inner surface of the fixing belt 201 is a surface that directly contacts the fixing belt 201 and is a nip forming surface.

The fixing belt 201 is made of a metal belt such as nickel or SUS, or an endless belt or film using a resin material such as polyimide. The surface layer of the fixing belt 201 has a mold release layer such as a PFA or PTFE layer, and has a mold release property so that toner does not adhere. An elastic layer formed of a layer of silicone rubber or the like may be provided between the base material of the fixing belt 201 and the PFA or PTFE layer. If there is no silicone rubber layer, the heat capacity will be smaller and the fixability will be improved. There may be a problem that uneven gloss (Yuzu skin image) remains. In order to improve this, it is necessary to provide a silicone rubber layer of 100 [μm] or more. Due to the deformation of the silicone rubber layer, minute irregularities are absorbed and the yuzu skin image is improved.

The stay member 207 has a shape having an upright portion on the side opposite to the nip N side, and halogen heaters 202A and 202B as heat sources for heating the fixing belt 201 are arranged across the upright portion, and the fixing belt 201 is arranged. Is directly heated by radiant heat from the inner surface side by the halogen heaters 202A and 202B.

A nip forming member 206 and a stay member 207 as a supporting member for supporting the nip portion N are provided inside the fixing belt 201 to prevent the nip forming member 206 receiving pressure from the pressure roller 203 from bending and in the axial direction. To obtain a uniform nip width. The stay member 207 is held, fixed, and positioned on a flange (not shown) as a holding member at both ends. Further, a reflective member 209 is provided between the halogen heaters 202A and 202B and the stay member 207 to suppress wasteful energy consumption due to the stay member 207 being heated by radiant heat from the halogen heaters 202A and 202B. Here, instead of providing the reflective member 209, the same effect can be obtained by performing heat insulation or mirror surface treatment on the surface of the stay member 207.

The pressure roller 203 has an elastic rubber layer 204 wound around a core metal 205, and a mold release layer (PFA or PTFE layer) is provided on the surface in order to obtain mold releasability. The pressure roller 203 rotates by transmitting a driving force from a drive source such as a motor provided in the image forming apparatus 100 via a gear. Further, the pressure roller 203 is pressed against the fixing belt 201 side by a spring or the like, and the elastic rubber layer 204 is crushed and deformed to have a predetermined nip width.

The pressure roller 203 may be a hollow roller, or the pressure roller 203 may have a heating source such as a halogen heater. The elastic rubber layer 204 may be solid rubber, but if there is no heater inside the pressure roller 203, sponge rubber may be used. Sponge rubber is more preferable because it has higher heat insulating properties and is less likely to lose heat from the fixing belt 201.

The fixing belt 201 is rotated around by the pressure roller 203. In the case of FIG. 2, the pressure roller 203 is rotated by the drive source, and the driving force is transmitted to the fixing belt 201 by the nip portion N, so that the fixing belt 201 is rotated. The fixing belt 201 is sandwiched between the nip portions N and rotates, and is guided by flanges (not shown) at both ends except the nip portion N to travel.

With the above configuration, it is possible to realize the fixing device 200 which is inexpensive and has a quick warm-up.

The fixing device 200 according to the present embodiment has a function of performing control for diagnosing the life of the fixing device 200. The term "life" as used herein means that as the fixing device 200 continues to be used, the parts deteriorate and the rotational torque becomes heavy, causing problems such as paper jams.

The life diagnosis control unit 400 shown in FIG. 2 was detected by the fixing belt temperature sensor 410 that detects the temperature of the fixing belt 201 and the in-flight temperature sensor 413 that detects the temperature inside the main body (inside the machine) of the image forming apparatus 100. The life of the fixing device 200 is diagnosed based on the temperature (detection output). The fixing belt temperature sensor 410 is composed of, for example, a non-contact temperature sensor. The life diagnosis control unit 400 and the fixing belt temperature sensor 410 correspond to the life diagnosis control means and the temperature detection member of the present invention, respectively.

Prior to the description of the functional configuration of the life diagnosis control unit 400 (see FIG. 4), the control configuration of the image forming apparatus 100 will be described with reference to FIG.

As shown in FIG. 3, in the control configuration of the image forming apparatus 100, a ROM 301 for storing various programs, a CPU 302 for executing various programs stored in the ROM 301, a RAM 303 for reading and writing processing results by the CPU 302, and various sensors. It includes an engine I / O unit 305 that exchanges information with the 307 and the drive system 304, and a main body interface (hereinafter referred to as a main body I / F) unit 306 that exchanges information with the operation unit 310.

In the control configuration shown in FIG. 3, the various sensors 307 include the fixing belt temperature sensor 410 and the in-flight temperature sensor 413 (see FIG. 2) only for the components related to the life diagnosis control of the fixing device 200. The CPU 302 realizes the life diagnosis control unit 400 (see FIGS. 2 and 4) by executing, for example, a life diagnosis program. The operation unit 310 functions as a notification means for displaying the life determination result by the life diagnosis control unit 400 as a message 320 (see FIG. 7).

Next, the control configuration of the fixing device 200 according to the present embodiment will be described with reference to FIG. As shown in FIG. 4, the fixing device 200 has a life diagnosis control unit 400 that performs life diagnosis control of the fixing device 200. The life diagnosis control unit 400 controls each of the life diagnosis data storage means 401, the temperature detection means 402, the diagnosis timing determination means 403, the temperature environment determination means 404, the diagnosis drive control means 405, the life diagnosis means 406, and the life notification means 407. It has components.

The life diagnosis control unit 400 includes a life diagnosis program in which the CPU 302 is stored in, for example, the ROM 301 together with the diagnosis timing determination means 403, the temperature environment determination means 404, the diagnosis drive control means 405, the life diagnosis means 406, the life notification means 407, and the like. These are the various functions realized by executing.

The life diagnosis data storage means 401 stores information on the temperature (hereinafter referred to as the life diagnosis temperature) as a diagnostic value for diagnosing that the fixing device 200 has reached the end of its life. The life diagnosis temperature can be derived from, for example, the graph shown in FIG. 5, and this point will be described in detail later. As the life diagnosis data storage means 401, for example, a predetermined storage area of the ROM 301 can be allocated.

The temperature detecting means 402 detects the temperature of the object to be measured, and the fixing belt temperature sensor 410 and the in-machine temperature sensor 413 are mounted in the base of the image forming apparatus 100.

The diagnosis timing determination means 403 determines whether or not the life determination timing (timing) has been reached. The diagnosis timing determination means 403, for example, takes in data of the counting result (number of prints) from the number counter 420 for counting the number of prints, and diagnoses the life when the number of prints indicated by the data reaches a predetermined number set in advance. It is determined that the timing has been reached. The number counter 420 corresponds to the counting means of the present invention.

The temperature environment determining means 404 determines whether or not the fixing device 200 has a temperature environment suitable for life diagnosis based on the temperature of each part detected by the temperature detecting means 402. In the temperature environment determination means 404, for example, the difference between the temperature of the fixing belt 201 detected by the fixing belt temperature sensor 410 and the temperature inside the main body (inside the machine) of the image forming apparatus 100 detected by the in-machine temperature sensor 413 is predetermined. When the temperature is smaller than the set temperature, it is determined that the temperature environment is suitable for life diagnosis.

The diagnostic drive control means 405 is a non-heating rotary drive that drives the pressurizing roller 203 and the fixing belt 201 without heating by the halogen heaters 202A and 202B when the fixing device 200 is in a temperature environment suitable for life diagnosis. (Hereinafter, it may also be referred to as drive control at the time of diagnosis). Needless to say, even during this non-heating rotary drive, the fixing belt 201 is driven by the pressure roller 203 and is rotated around.

Specifically, the diagnostic drive control means 405 is determined by the diagnostic timing determining means 403 to reach the diagnostic timing after the power of the image forming apparatus 100 is turned on, and is suitable for the diagnosis of the life by the temperature environment determining means 404. When it is determined that the temperature environment is satisfied, the diagnostic drive control for rotating the pressurizing roller 203 and the fixing belt 201 while the heating by the halogen heaters 202A and 202B is stopped is executed for a predetermined period. The drive control at the time of diagnosis is the temperature of the fixing belt 201 after the transition from the hot time in which the rotation of the pressurizing roller 203 and the heating by the halogen heaters 202A and 202B are performed to the cold time in which the rotation and heating are stopped. Is carried out in a state where is sufficiently lowered.

The life diagnostic means 406 is provided with the fixing device 200 based on the temperature of the fixing belt 201 detected by the fixing belt temperature sensor 410 during the non-heated rotary drive by the above-mentioned drive control at the time of diagnosis and the preset life diagnosis temperature. It determines whether or not the product has reached the end of its useful life. Specifically, the life diagnostic means 406 sequentially captures the temperature of the fixing belt 201 detected by the fixing belt temperature sensor 410 throughout the above-mentioned predetermined period in which the non-heating rotary drive is performed. On the other hand, the life diagnosis means 406 reads the life diagnosis temperature data from the life diagnosis data storage means 401, and the fixing belt 201 detected by the fixing belt temperature sensor 410 during the predetermined period (non-heating rotation drive period). It is determined whether or not the life has been reached based on the temperature change and the preset life diagnosis temperature.

The life notification means 407 notifies that when the life diagnosis means 406 diagnoses that the fixing device 200 has reached the end of its life. As shown in FIG. 7, the life notification means 407 displays, for example, a message 320 indicating that the fixing unit has reached the end of its life in the display area 310a of the touch panel of the operation unit 310. The life notification means 407 is not limited to displaying a message 320 indicating that the life has been reached, and may have other configurations such as notifying the user of the end of the life by sound.

Next, a method of selecting the life diagnosis temperature used by the life diagnosis means 406 for the life diagnosis of the fixing device 200 will be described.

FIG. 5 shows the unit torque when the pressurizing roller 203 is rotated without heating by the halogen heaters 202A and 202B and the fixing belt 201 is rotated with respect to the pressurizing roller 203 when it is cold. It is a graph which shows the relationship of the temperature of the fixing belt 201. This graph shows, in particular, the relationship when the outside air temperature is 23 ° C.

In FIG. 5, the unit torque on the horizontal axis is determined based on the torques of four units (fixing devices) having different torques when normally heated and used. Under the machine conditions this time, the target value that is not judged to be the life of the unit (fixing device 200) is 0.8 Nm or less, so the unit plotted on the rightmost side of the graph is the torque NG unit, that is, the life is reached. It is a unit, and it suffices if it can be detected.

A temperature sensor for control is used for belt (fixing belt) temperature detection. As shown in the graph of FIG. 5, there is a correlation between the belt temperature and the unit torque. That is, from the graph of FIG. 5, it can be read that even if the belt has the same rotation time, the sensitivity of the temperature of the belt to torque is small when the rotation time of the belt is short, and the sensitivity becomes better as the rotation time is longer. Can be done. According to the example of the graph shown in FIG. 5, under the condition that the belt is driven for 60 seconds, the temperature of the durable (in use) belt may be about 4 degrees (deg) higher than that of the new belt. I understand. This temperature (4 degrees) corresponds to the temperature change between points P1 and P2 in FIG.

Further, it can be seen that under the condition of driving for 120 seconds, the temperature of the durable belt (in use) is about 7 degrees higher than that of the new belt. This temperature (7 degrees) corresponds to the temperature change between points P3 and P4 in FIG. Further, it can be seen that under the condition of driving for 300 seconds, the temperature of the durable belt (in use) is significantly higher than the temperature (7 degrees) when driven for 120 seconds with respect to the new belt.

In the case of a fixing unit equipped with a belt (fixing belt 201) having a temperature change characteristic (heating characteristic) as shown in the graph of FIG. 5, the belt is driven for 120 seconds or more in order to more accurately diagnose the life. Is preferable. Since the heat source that determines the temperature of the belt is the frictional heat with the elastic rubber layer 204 of the pressure roller 203, the optimum rotation time differs depending on various conditions such as the material and thickness of the belt, the outer diameter, and the rotation speed. .. Therefore, it is necessary to set the conditions so that there is temperature sensitivity and the measurement time is short. In the present embodiment, a fluorine compound such as PFA or PTFE is preferable as the material of the surface layer of the fixing belt 201. Further, it is preferable not to apply oil. Further, although there is no particular limitation, it is preferable that the belt speed of the nip portion N is high because frictional heat generation is likely to occur.

Based on this point, in the present embodiment, from the temperature rise characteristic corresponding to the drive time shown in the graph of FIG. 5, the life diagnosis temperature is the life diagnosis temperature a1 corresponding to the temperature near the torque NG and the temperature exceeding the torque NG. The life diagnosis temperature a2 corresponding to the above is determined, and the life diagnosis temperatures a1 and a2 are stored in advance in the life diagnosis data storage means 401. The torque for determining the torque NG is, for example, a torque that may cause a problem such as a paper jam due to deterioration of parts.

Next, the life diagnosis control operation of the fixing device 200 by cold drive in the life diagnosis control unit 400 will be described with reference to FIG.

In order to perform the life diagnosis control, first, the timing for measuring the temperature of the fixing belt 201, that is, the life diagnosis timing is determined first. In this case, it is desirable to start from a timing earlier than the expected life. In the present embodiment, the assumed life is assumed that the number of printed sheets reaches 100 k (k = 1000), and the specification is such that measurement is performed from 70 k sheets. After that, the temperature of the fixing belt 201 was measured every 10k sheets until the temperature of the fixing belt 201 reached a predetermined temperature (for example, the life diagnosis temperature a1 described above). The temperature measurement interval of the fixing belt 201 is not limited to the above-mentioned 10k sheet interval, and can be arbitrarily set, and the temperature is set until the temperature rise reaches the NG level (for example, the life diagnosis temperature a2). Just do it.

In the life diagnosis control shown in FIG. 5, the life determination control unit 401 first determines whether or not the power of the image forming apparatus 100 is turned on (ON) (step S1). If it is determined that the power is not turned on (NO in step S1), the process of step S1 is continued.

During this period, if it is determined that the power is turned on (YES in step S1), the diagnosis timing determination means 403 determines whether or not the diagnosis timing has been reached (step S2). Here, the diagnostic timing determining means 403 acquires, for example, the currently counted number of prints from the number counter 420 based on the above-mentioned diagnostic timing setting, and has not reached the diagnostic timing when the number of prints is less than 70 k. (NO in step S2), and the process is terminated.

On the other hand, when the number of printed sheets is 70 k or more, the diagnosis timing determination means 403 determines that the diagnosis timing has been reached (YES in step S2), and proceeds to the process of step S3 and subsequent steps.

As a result, after the processing of step S2, first, the temperature environment determination means 404 determines the temperature difference between the in-flight temperature detected by the in-flight temperature sensor 413 and the temperature of the fixing belt 201 detected by the fixing belt temperature sensor 410. Calculate (step S3).

Next, the temperature environment determination means 404 determines whether or not the temperature difference calculated in step S3 is a preset temperature, for example, 5 degrees or less (step S4). When it is determined that the temperature difference is not 5 degrees or less (NO in step S4), the temperature environment determination means 404 continues the process of step S4. In the fixing device 200, frictional heat cannot be detected when the fixing belt 201 is in a hot state. Step S4 is a process for confirming the cold state by comparing the temperature difference between the temperature inside the machine and the fixing belt 201.

If it is determined that the temperature difference is 5 degrees or less during the process of step S4 (YES in step S4), the diagnostic drive control means 405 continues to be the fixing device for a predetermined period in the cold state. Control is performed to rotationally drive (cold drive) the 200 (step S5). Specifically, the diagnostic drive control means 405 has shifted from a hot time in which the rotation of the pressurizing roller 203 and the driving of the halogen heaters 202A and 202B are performed simultaneously to a cold time in which the rotation and heating are stopped. After confirming by the determination result of S5, the pressure roller 203 is driven in a non-heated rotation for a predetermined period, that is, for 120 seconds in the setting of the present embodiment in the cold state, and is driven by the pressure roller 203. The fixing belt 201 is also rotated (carried).

The diagnostic drive control means 405 sets the pressurizing roller 203 and the fixing belt 201 in a non-heated rotation drive (cold drive) in the cold state in step S5 for a predetermined period, for example, a period in which the fixing belt 201 rotates one round or more. May be. In this case, by rotating the fixing belt 201 one or more turns during the non-heating rotation drive (cold drive), the variation in the detection temperature in the circumferential direction of the fixing belt 201 can be averaged, and more frictional heat can be generated. It can be generated to increase the sensitivity to torque.

In the cold drive in step S5, the pressurizing state of the pressurizing roller 203 is controlled to the same value as, for example, when passing paper. However, the present invention is not limited to this, and if the drive motor for driving the pressurizing roller 203 has a margin, the temperature rise may be accelerated by increasing the pressure or increasing the rotation speed. For example, regarding the rotation speed of the fixing belt 201, the pressurizing roller 203 and the fixing belt 201 may be rotationally driven at a rotation speed higher than the rotation speed at the time of normal printing (printing). If the rotation speed of the fixing belt 201 during cold drive is higher than the rotation speed during normal printing, frictional heat generation becomes large and the waiting time for performing life diagnosis is reduced, which is preferable.

As a process following step S5, the life diagnosis means 406 executes a process of measuring the temperature of the fixing belt 201 while the heating is stopped by the drive control means 405 at the time of diagnosis (step S6). Here, the life diagnosis means 406 takes in the detection output of the fixing belt temperature sensor 410, processes the detection output, and measures the temperature of the fixing belt 201. The measurement of the temperature of the fixing belt 201 is continued for the predetermined period during which the cold drive in step S5 is carried out.

Subsequently, the life diagnosis means 406 reads the data of the life diagnosis temperatures a1 and a2 from the life diagnosis data storage means 401, and the temperature rise result of the fixing belt 201 measured during the predetermined period, that is, the predetermined value. It is determined whether or not the temperature change of the fixing belt 201 detected by the fixing belt temperature sensor 410 during the period is equal to or higher than the life diagnosis temperature a1 (step S7).

Here, when it is determined that the temperature change of the fixing belt 201 during the predetermined period is not equal to or higher than the life diagnosis temperature a1 (NO in step S7), the process returns to the first process.

On the other hand, when it is determined that the temperature change of the fixing belt 201 during the predetermined period is equal to or higher than the life diagnosis temperature a1 (YES in step S7), the life diagnosis means 406 then changes the temperature of the fixing belt 201 to the above. It is determined whether or not the life diagnosis temperature is a2 or higher (step S8).

Here, when it is determined that the temperature rise range of the fixing belt 201 is not equal to or higher than the life diagnosis temperature a2 (NO in step S8), the life notification means 407 notifies that the life of the fixing device 200 is near (NO). Step S9). Specifically, the life notification means 407 is displayed in the display area 310a of the touch panel of the operation unit 310, for example, as shown in FIG. 7, a message 320 such as "The fixing unit is about to reach the end of its life. Please contact the service." Is controlled to display.

After that, this life diagnosis process returns to the beginning. According to the life diagnosis timing setting described above in the present embodiment, the next life diagnosis process is executed after printing 10 k sheets, and thereafter, it is repeatedly executed every time printing of 10 k sheets is completed. ..

On the other hand, when it is determined that the temperature change of the fixing belt 201 during the predetermined period is equal to or higher than the life diagnosis temperature a2 (YES in step S8), the life notification means 407 indicates that the fixing device 200 has reached the end of its life. Notify (step S10). Specifically, the life notification means 407 displays a message having a higher degree of caution than the message 320 shown in FIG. 7 in the display area 310a of the touch panel of the operation unit 310. Specifically, for example, control is performed to display a message such as "The fixing unit has reached the end of its life. It will be stopped soon. Please contact the service immediately." After that, this life diagnosis process ends.

In this way, it is useful for the life diagnosis control unit 400 to change the display method, such as displaying a display indicating that the fixing belt 201 should be replaced immediately when the temperature change within a predetermined period exceeds NG. be. It is necessary to decide whether to stop the machine operation, that is, whether to send a message such as "It will stop soon" according to the characteristics of the machine. Normally, the number of units used is determined by assuming the usage conditions of the user who is strict in how to use it, and the units of all machines are replaced even if they can be used sufficiently, but in this embodiment, they can be practically used. It became possible to use it.

In the life diagnosis control shown in FIG. 6, the temperature of the fixing belt 201 is measured by cold driving for a predetermined period, and the temperature rise range of the fixing belt 201 in the predetermined period is the torque NG level of the fixing unit. The life is diagnosed according to whether or not the temperature is equal to or higher than the above temperature, but the life is not limited to this. The life may be diagnosed according to the inclination of the temperature rise of the belt 201.

Further, in the present embodiment, as a function of the drive control means 405 at the time of diagnosis, a control function for periodically checking the rotation of the fixing belt 201 during non-heating rotation drive is provided based on the counting result of the number counter 420. You may. By this control function, for example, every time the number of printed sheets reaches a predetermined number, or continuously between the pressurizing roller 203 and the fixing nip, the transport interval of the recording material S (distance between papers). ) Increases, the predetermined period during which the non-heating rotation drive is performed in step S5 and the rotation speed of the fixing belt 201 can be adjusted. Further, according to the above-mentioned predetermined period and the configuration in which the rotation speed of the fixing belt 201 can be adjusted, it is possible to grasp the time-dependent fluctuation of the fixing device 200 and perform a highly accurate life diagnosis.

In the fixing device 200 according to the present embodiment, a sliding fixing mechanism is configured by a fixing belt 201, a pressure roller 203, and a nip component, and a lubricant is applied to a sliding portion between the back surface of the fixing belt 201 and the nip component. To use. Since the lubricant has the property that the clay drops at room temperature and the clay rises at high temperature, in the sliding fixing structure, the fixing belt 201 and the pressure roller 203 are rotationally driven at room temperature when fixing. There is no such thing, and it is designed to be done in a heated state. This is to prevent the clay of the lubricant from falling and becoming a high torque at room temperature. For this reason, in the sliding fixing structure, the temperature difference is buried in the above-mentioned heated state, that is, in the hot state. Therefore, the temperature change suitable for estimating the rotational torque must be extracted in the cold state (cold state). Can't be done.

In view of this point, in the present embodiment, when the temperature of the fixing belt 201 is lowered to a temperature at which a sufficient frictional force can be obtained, the fixing belt 201 is rotated without heating for a predetermined period, and the fixing belt 201 is rotated in the predetermined period. In order to determine the life according to the temperature change, the fixing belt 201 is efficiently generated by the frictional force with the pressure roller 203, and the torque increase value is estimated from the temperature change of the fixing belt 201 at that time to accurately predict the life. Will be able to do.

As described above, the present embodiment includes a lifespan diagnosis control unit 400 that controls to diagnose the lifespan of the fixing device 200, and the lifespan diagnosis control unit 400 is a cold state in which heating by the halogen heaters 202A and 202B is stopped. In this state, the pressure roller 203 and the fixing belt 201 are rotated for a predetermined time (predetermined period) to measure the temperature of the fixing belt 201 due to frictional heat, and the life is determined based on the temperature rise result of the fixing belt 201 in the predetermined period. It is a configuration that controls. That is, in the present embodiment, the life determination control is performed according to how many times the temperature of the fixing belt 201 has risen (result of temperature rise) within the predetermined period.

With this configuration, in the present embodiment, the life can be determined by using the temperature sensor (for example, the fixing belt temperature sensor 410) always arranged in the fixing device 200, the configuration change is unnecessary, and the cost increase is avoided. can. Compared with the conventional method in which members such as rollers are replaced uniformly with the number of sheets used, it is possible to suppress the disposal of members in a state where they can still be used, and to use them until the functional life is reached.

Further, in the present embodiment, the life diagnosis control unit 400 controls to determine the life by rotating the fixing belt 201 one or more turns in the cold state. Thereby, in the present embodiment, the variation in the detection temperature in the circumferential direction of the fixing belt 201 can be averaged by rotating the fixing belt 201 one or more turns by the rotation drive control in the cold state. The longer the fixing belt 201 is rotated under the condition that it is rotated more than once, the more frictional heat is generated, the higher the sensitivity to torque, and the higher the accuracy.

Further, in the present embodiment, the life diagnosis control unit 400 rotates the fixing belt 201 at a rotation speed higher than the rotation speed at the time of normal printing in the cold state. As a result, in the present embodiment, by increasing the rotation speed of the fixing belt 201 by the rotation drive control in the cold state, a large amount of frictional heat is generated, and whether or not the fixing device 200 has reached the end of its life can be determined in a short time. You can judge.

Further, in the present embodiment, the life diagnosis control unit 400 periodically checks the rotation of the pressure roller 203 and the fixing belt 201 in a cold state based on the counting result of the number counter 420. There is. As a result, in the present embodiment, it is possible to check the rotation based on the fact that the predetermined number of prints has been reached and the transfer interval (historical distance between papers) of the recording material S has increased, and the fixing device 200 can be checked for rotation. It is possible to grasp the fluctuation with time and perform highly accurate life diagnosis.

Further, in the present embodiment, the nip forming member 206 has a configuration of being a metal plate. As a result, in the present embodiment, the temperature becomes uniform in the axial direction due to the heat conduction of the metal plate, and a minute temperature rise can be accurately measured.

Further, in the present embodiment, the fixing belt temperature sensor 410 is composed of a non-contact temperature sensor. With this configuration, in the present embodiment, the temperature of the fixing belt 201 is detected in a non-contact manner, so that a minute temperature rise can be accurately measured without affecting the temperature rise of the fixing belt 201 due to the frictional force.

Further, in the fixing device 200 according to the present embodiment, in addition to the fixing belt 201, the pressurizing roller 203, the halogen heaters 202A and 202B, and the fixing belt temperature sensor 410, whether or not the life diagnosis timing has been reached is determined. The diagnostic timing determining means 403 for determining, the temperature environment determining means 404 for determining whether or not the temperature environment is suitable for the life diagnosis based on the temperature of the fixing belt 201, and the diagnostic timing are reached after the power is turned on. The pressure roller 203 and the fixing belt 201 are rotated in a cold state in which heating by the halogen heaters 202A and 202B is stopped for a predetermined period by determining that the temperature environment is suitable for the diagnosis of the life. Based on the diagnostic drive control means 405 that performs diagnostic drive control, the temperature change of the fixing belt 201 detected by the fixing belt temperature sensor 410 during a predetermined period, and the preset life diagnosis temperature (a1, a2). It has a lifespan diagnosing means 406 for determining whether or not the life has been reached, and a lifespan notifying means 407 for notifying the fact when it is determined that the life has been reached.

With this configuration, the fixing device 200 according to the present embodiment is surely kept in a cold state at an appropriate diagnosis timing, and then the rotation torque is estimated while efficiently generating heat of the fixing belt 201 by the frictional force with the pressure roller 203. Therefore, the temperature of the fixing belt 201 suitable for this can be detected, and the life can be accurately determined from the estimated rotational torque. In addition, by notifying the user that the life has reached the end of the life, it is possible to promptly promptly respond to the situation.

With the above-described configuration, in the present embodiment, the fixing belt 201 for sliding fixing is efficiently generated by the frictional force with the pressure roller 203, and the torque increase value is estimated from the temperature of the fixing belt 201 at that time to be accurate. It is possible to provide a fixing device 200 and an image forming device 100 that enable a long life prediction.

In the present embodiment, the life diagnosis control unit 400 has a diagnosis timing determination means 403, a temperature environment determination means 404, a diagnosis drive control means 405, a life diagnosis means 406, and a life notification means 407. The invention is not limited to this, and various modifications are possible, such as one in which a part of these components is deleted, one in which a part of these components is added, or one in which each component having a structure different from that of the present embodiment is adopted.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and the technical scope of the present invention described in the claims includes various redesigned embodiments within the scope of the gist of the invention. Will be.

For example, in the present invention, the fixing device 200A having the structure shown in FIG. 8 may be adopted instead of the fixing device 200 having the structure shown in FIG. The fixing device 200A shown in FIG. 8 relates to another embodiment of the present invention, and is the same as the fixing device 200 in that it has a two-piece configuration of halogen heaters 202A and 202B, but the halogen heaters 202A and 202B. The arrangement position of is different from that of the fixing device 200.

In the fixing device 200A according to another embodiment, two halogen heaters 202A and 202B are arranged together on one side of the stay member 207A. Further, the fixing device 200A is different from the fixing device 200 in the configuration of the stay member 207A and the configuration of the reflection member 209A attached to the stay member 207A. The number of halogen heaters is not limited to two, but may be one, and may be configured to include three or more.

As described above, in the fixing device according to the present invention, the belt for sliding fixing is efficiently generated by the frictional force with the pressurizing member, and the torque increase value is estimated from the temperature of the belt at that time to be accurate. It has the effect of enabling life prediction. Therefore, the fixing device according to the present invention can be applied to a fixing device having a sliding fixing mechanism and an image forming device generally equipped with the fixing device.

100 Image forming device 200 Fixing device 201 Fixing belt (belt)
203 Pressurized roller (pressurized member)
206 Nip forming member 202A, 202B Halogen heater (heat source)
400 Lifespan diagnosis control unit (lifespan diagnosis control means)
401 Life diagnosis data storage means 402 Temperature detection means 403 Diagnosis timing judgment means 404 Temperature environment judgment means 405 Drive control means at the time of diagnosis 406 Life diagnosis means 407 Life notification means 410 Fixing belt temperature sensor (temperature detection member)
413 In-flight temperature sensor 420 Sheet counter

Japanese Unexamined Patent Publication No. 2016-130823

Claims (8)

A flexible, endless belt and
A pressure member provided on the outside of the belt and facing the belt,
A nip forming member provided inside the belt and forming a fixing nip between the belt and the pressurizing member, and a nip forming member.
The heat source that heats the belt and
A temperature detecting member that detects the temperature of the belt and
With life diagnosis control means,
The life diagnosis control means rotates the pressurizing member and the belt for a predetermined period in a cold state in which heating by the heat source is stopped, measures the temperature of the belt due to frictional heat, and raises the temperature of the belt. A fixing device characterized in that life judgment control is performed based on the temperature result. The fixing device according to claim 1, wherein the life diagnosis control means is controlled so as to determine the life by rotating the belt one or more turns in the cold state. The fixing device according to claim 1, wherein the life diagnosis control means rotates the belt at a rotation speed higher than the rotation speed at the time of normal printing in the cold state. The life diagnosis control means is characterized in that it periodically checks the rotation of the pressure member and the belt in the cold state based on the counting result of the counting means for counting the number of printed sheets. The fixing device according to 1. The fixing device according to claim 1, wherein the nip forming member is a metal plate. The fixing device according to claim 1, wherein the temperature detecting member is a non-contact temperature sensor. A flexible, endless belt and
A pressurizing member provided on the outside of the belt and facing the belt at the arrangement position of the nip forming member provided on the inside of the belt.
The heat source that heats the belt and
A temperature detecting member that detects the temperature of the belt and
A diagnostic timing determining means for determining whether or not the diagnostic timing for diagnosing the life of the fixing device has been reached, and
A temperature environment determining means for determining whether or not the temperature environment is suitable for diagnosing the life based on the temperature of the belt, and
After the power is turned on, it is determined that the diagnosis timing has been reached, and the temperature environment is suitable for the diagnosis of the life, so that the heating is stopped in the cold state for a predetermined period. A diagnostic drive control means for performing diagnostic drive control to rotate the pressure member and the belt, and a diagnostic drive control means.
A life diagnosis means for determining whether or not the life has been reached based on the temperature change of the belt detected by the temperature detecting member during the predetermined period and the preset life diagnosis temperature.
When it is determined that the life has been reached, a notification means for notifying that fact and a notification means to that effect,
A fixing device characterized by having. An image forming apparatus comprising the fixing apparatus according to any one of claims 1 to 7.

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