JP2005070510A - Fixing controller, image forming apparatus, and fixing control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to properly and safely deal with the abnormality of a fixing device during the stop of a rotational driving source in a way as to prevent the occurrence of a failure, such as the breakage of a belt and the permanent set of the belt, in case of the occurrence of such abnormality in utilizing an induction heating system. <P>SOLUTION: When the abnormality of the fixing device, for example, the high-temperature abnormality due to the runaway etc., of an inverter circuit, is detected during the stoppage of a fixing motor (Y of S 1, N of S 2, S 4), the fixing motor is forcibly turned on to forcibly rotate the fixing belt (S 5), thereby heating the fixing belt in a rotating state even if the induction heating of the fixing belt is continued. The avoidance of the failure in case of the induction heating in at least the stop state, for example, the breakage of a belt and the permanent set of the belt, is made possible. Also, in case of the occurrence of such abnormality, a relay is turned off (S 6) and the power source supply to the induction heating circuit is turned off, by which a reliable measure for safety is obtained. Further, the user is instructed to make a report (S 6) such that the user can be set to employ a proper measure, such as inspection, and a further reliable measure for safety can be obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fixing control device for an induction heating type fixing device, an image forming apparatus such as an electrophotographic copying machine, a printer, and a facsimile machine including such a fixing control device, and a fixing control method.

  An image forming apparatus such as a copying machine or a printer forms an image on a recording medium such as plain paper or OHP. This image forming apparatus employs an electrophotographic system in view of high speed image formation, image quality, cost, and the like. The electrophotographic method is a method in which a toner image is formed on a recording medium, and the formed toner image is fixed on the recording medium with heat and pressure. The heat roller method is currently the most widely used fixing method from the standpoint of safety. Has been.

  In the heat roller system, a heat roller heated by a heat generating member such as a halogen heater and a pressure roller disposed opposite to the heat roller are pressed to form a mutual pressure contact portion called a nip portion, and a toner image is formed in the nip portion. This is a method of heating through a recording medium to which is transferred.

  In recent years, environmental problems have become important and image forming apparatuses such as copiers and printers have been saving energy.

  In considering the energy saving of this image forming apparatus, what cannot be ignored is the power saving of the fixing device for fixing the toner to the recording medium.

  In order to reduce the power consumption of the fixing device during standby of the image forming apparatus, the temperature of the heating roller is maintained at a constant temperature slightly lower than the fixing temperature during standby, so that the temperature can be immediately raised to a usable temperature during use. The temperature of the fixing roller is not waited for. In this case, extra energy is consumed by supplying a certain amount of power even when the fixing device is not used.

  It is desired to reduce power consumption during standby and to further reduce power consumption. In addition, an induction heating fixing method is employed in order to shorten the heating time of the heating roller. An induction heating type fixing device is attracting attention as a method that contributes to environmental problems because it can dramatically shorten the heating time or rise time and has high efficiency.

  Here, in this type of induction heating fixing method, for example, when heating by induction heating with the fixing belt or the like stopped, the temperature rises locally at a stretch, causing belt breakage, belt permanent deformation, May lead to accidents such as smoke and fire.

  There are many patent documents relating to this type of induction heating and fixing method, and examples of the operation stoppage include the following.

  For example, according to Patent Document 1, in the induction heating fixing device, when a signal is not obtained from the rotation detection unit for a predetermined time, the operation of the inverter circuit unit is stopped.

  Further, according to Patent Document 2, in the induction heating fixing device, when the fixing belt becomes a predetermined speed or less, the rotation of the rotating body is stopped and the power supply to the magnetic flux generating means is cut off.

  According to Patent Document 3, in the induction heating fixing device, when it is determined that the toner heating medium is in a stopped state, heating by electromagnetic induction of the induction heating unit is stopped.

  According to Patent Document 4, the induction heating fixing device has an automatic pressure releasing means for the fixing roller by rotating the fixing motor in the reverse direction, and the pressure state cannot be detected in a predetermined time by a sensor that detects the pressure state of the fixing roller. Sometimes it is determined that there is no fixing device.

JP 2002-082549 A JP2003-015445A JP 2001-318546 A JP 2003-091202 A

  However, in the case of the conventional examples shown in these Patent Documents 1 to 4 and the like, although the point of avoiding induction heating when the fixing belt or the like is stopped is taken into consideration, the fixing belt or the like is originally rotationally driven. This assumes an abnormal situation under the circumstances.

  That is, for example, an induction heating circuit that energizes an induction coil or the like for induction heating of a fixing belt or the like, in general, an inverter circuit, even though a fixing heated member such as a fixing belt is in a stopped state. For example, no consideration is given to a case where an abnormality occurs, for example, when the inverter circuit runs away. In such a case, the induction coil is energized by the runaway inverter circuit, and the stationary fixing belt or the like is inductively heated by the induction coil, causing the belt damage, the belt permanent deformation, or the like as described above.

  In the present invention, when using the induction heating method, it is possible to appropriately and safely cope with problems such as belt breakage and belt permanent deformation when an abnormality occurs in the fixing device while the rotation drive source is stopped. It is.

  According to a first aspect of the present invention, there is provided a fixing control device including a fixing member to be heated that includes at least a rotating member that is rotationally driven, a rotation driving source that rotates the rotating member, and induction that heats the fixing member to be heated. A heating unit, an induction heating circuit that drives the induction heating unit, a fixing device abnormality detecting unit that detects whether or not the fixing device is abnormal while the rotation drive source is stopped, and an abnormality caused by the fixing device abnormality detecting unit An abnormality control means for forcibly rotating the rotating member by the rotation drive source when detected.

  Therefore, when an abnormality of the fixing device is detected while the rotation drive source is stopped, the rotation member is forcibly rotated by the rotation drive source, so that the rotation is performed even if induction heating of the heated member for fixing by the induction heating unit is continued. Heating in a state is avoided, and at least a problem in the case of induction heating in a stopped state is avoided.

  According to a second aspect of the present invention, there is provided the fixing control device according to the first aspect, further comprising a rotation detection sensor that detects the rotation of the rotating body, wherein the fixing device abnormality detection means is driven to rotate by the output of the rotation detection sensor. Determine when the source is shut down.

  Therefore, since this type of device is generally provided with a rotation detection sensor, the invention according to claim 1 can be easily realized by using the rotation detection sensor.

  According to a third aspect of the invention, there is provided the fixing control device according to the first or second aspect, further comprising a temperature sensor that detects a temperature of the fixing member to be heated, and the fixing device abnormality detecting means is detected by the temperature sensor. When the temperature of the fixing member to be heated exceeds a predetermined value, it is detected as an abnormality of the fixing device.

  Accordingly, in general, this type of apparatus is provided with a temperature sensor for detecting the temperature of the fixing member to be heated. Therefore, the invention according to claim 1 or 2 can be easily realized by using the temperature sensor.

  According to a fourth aspect of the present invention, in the fixing control device according to any one of the first to third aspects, the induction heating means is an exciting coil, and the induction heating circuit supplies a high frequency current to the exciting coil. It is.

  Therefore, the present invention can be suitably applied when an abnormality occurs such that the inverter circuit runs away while the rotary drive source is stopped. That is, it becomes an appropriate safety measure when the inverter circuit runs away.

  According to a fifth aspect of the present invention, in the fixing control device according to any one of the first to fourth aspects, at least a heat resistant belt as the rotating member, a first support roller inscribed in the heat resistant belt, A second support roller that rotatably supports the heat-resistant belt between the first support roller and the heated member for fixing; the first support roller and the heat-resistant belt; At least one is induction-heated by the induction heating means.

  Therefore, various methods can be applied as the induction heating method, and in particular, it can be suitably applied to a belt method using a heat-resistant belt that causes problems such as belt breakage or belt permanent deformation by receiving induction heating in a stopped state. .

  According to a sixth aspect of the present invention, there is provided the fixing control device according to any one of the first to fifth aspects, further comprising a relay provided in an energization path for the induction heating circuit to intermittently supply power to the induction heating circuit. The abnormality control means forcibly rotates the rotating member by the rotation drive source when the abnormality is detected by the fixing device abnormality detection means, and turns off the relay to supply power to the induction heating circuit. cut off.

  Therefore, in addition to avoiding the continuation of induction heating in the stopped state, the relay is turned off and the power supply to the induction heating circuit is cut off.

  According to a seventh aspect of the present invention, in the fixing control device according to any one of the first to sixth aspects, when the abnormality is detected by the fixing device abnormality detecting unit, the abnormality control unit notifies the error by the notifying unit. Let

  Therefore, in the case where the abnormality is detected, in addition to the above-mentioned measures, the user is also notified through the notification means, so that the user can take appropriate measures such as inspection, and a more reliable safety measure. It becomes.

  According to an eighth aspect of the present invention, in the fixing control device according to any one of the first to seventh aspects, the abnormality control unit includes the fixing device when an abnormality is detected by the fixing device abnormality detecting unit. Error information is distributed to other terminals through a network to which the image forming apparatus is connected.

  Therefore, even when the user is away from the image forming apparatus, the user can be notified of the abnormality immediately through the network, and the user can take appropriate measures such as inspection, and more. This is a reliable safety measure.

  According to a ninth aspect of the present invention, there is provided an image forming apparatus comprising: a fixing device having a fixing member to be heated that is heated by an induction heating method; a printer engine including a photosensitive member; and other electrophotographic process members; and the fixing member to be heated. And a fixing control device according to any one of claims 1 to 8.

  Accordingly, since the fixing control device according to any one of claims 1 to 8 is provided, the same operation as in the case of the invention according to claims 1 to 8 is achieved.

  According to a tenth aspect of the present invention, there is provided a fixing member to be heated that includes at least a rotating member that is rotationally driven, a rotation driving source that rotates the rotating member, and induction heating means that electromagnetically heats the fixing member to be heated. A fixing control method by a fixing control device comprising an induction heating circuit for driving the induction heating means, and a fixing device abnormality detecting step for detecting whether or not the fixing device is abnormal while the rotation drive source is stopped; And an abnormality control step of forcibly rotating the rotating member by the rotation driving source when an abnormality is detected by the fixing device abnormality detecting step.

  Therefore, when an abnormality of the fixing device is detected while the rotation drive source is stopped, the rotation member is forcibly rotated by the rotation drive source, so that the rotation is performed even if induction heating of the heated member for fixing by the induction heating unit is continued. Heating is performed in the state, and at least problems in the case of induction heating in the stopped state are avoided.

  According to the present invention, when an abnormality of the fixing device, for example, a high temperature abnormality due to a runaway of an inverter circuit as an induction heating circuit or the like is detected while the rotation drive source is stopped, the rotation member is forcibly rotated by the rotation drive source. Due to this, even if induction heating of the fixing member to be heated by the induction heating means, for example, the heat-resistant belt, continues to be heated in the rotating state, troubles in the induction heating in the stopped state, for example, belt breakage or belt permanent deformation Etc. can be avoided at least. In addition, when the abnormality occurs, turning off the relay and cutting off the power supply to the induction heating circuit can provide a reliable safety measure. Safe measures can be taken and even more secure safety measures can be taken.

  The best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a schematic front view showing an example of an electrophotographic image forming apparatus to which the present invention is applied. This image forming apparatus is an image forming apparatus having a copying function and other functions such as a printer function and a facsimile function. The copying function, the printer function, and the facsimile function are sequentially switched by an application switching key of the operation unit. It is possible to select. The copy mode is selected when the copy function is selected, the print mode is selected when the printer function is selected, and the facsimile mode is selected when the facsimile mode is selected.

  First, in the copy mode, the operation is as follows. In an automatic document feeder (hereinafter referred to as ADF) 101, a document bundle on which a document is placed on a document table 102 is placed on the document table 102 when the start key on the operation unit is pressed. The paper is fed to a predetermined position on a document table 105 made of contact glass by a paper feed roller 103 and a feed belt 104. The ADF 101 has a count function that counts up the number of documents every time a document is fed. The document on the document table 105 is discharged onto a sheet discharge table 108 by a feeding belt 104 and a discharge roller 107 after image information is read by an image reading device 106 as an image input unit.

  When the document set detector 109 detects that the next document is present on the document table 102, the lowermost document on the document table 102 is similarly documented by the feed roller 103 and the feeding belt 104. The sheet is fed to a predetermined position on the table 105. After the image information is read by the image reading device 106, the document on the document table 105 is discharged onto the sheet discharge table 108 by the feeding belt 104 and the discharge roller 107. Here, the paper feed roller 103, the feed belt 104, and the discharge roller 107 are driven by a carry motor.

  The first paper feeding device 110, the second paper feeding device 111, and the third paper feeding device 112 as paper feeding means were loaded on the first tray 113, the second tray 114, and the third tray 115, respectively, when selected. A transfer sheet as a transfer material is fed, and the transfer sheet is conveyed to a position where it abuts on the photoconductor 117 by the vertical conveyance unit 116. The photoconductor 117 is a drum photoconductor and is driven to rotate by a main motor.

  Image data read from the original by the image reading device 106 is converted into optical information by a writing unit 118 as writing means via an image processing means (not shown), and the photoconductor 117 is uniformly charged by a charger (not shown). After that, it is exposed with light information from the writing unit 118 to form an electrostatic latent image. The electrostatic latent image on the photoconductor 117 is developed by the developing device 119 to become a toner image.

  The conveyance belt 120 serves as a sheet conveyance unit and a transfer unit, and a transfer bias is applied from a power source. The transfer belt 120 conveys the toner image on the photoconductor 117 while conveying the transfer paper from the vertical conveyance unit 116 at the same speed as the photoconductor 117. Transfer to transfer paper. The transfer paper is fixed with a toner image by a fixing device 121 and is discharged to a paper discharge tray 123 by a paper discharge unit 122. The photoreceptor 117 is cleaned by a cleaning device (not shown) after the toner image is transferred. Here, the photoconductor 117, the charger, the writing unit 118, the developing device 119, and the transfer unit constitute a printer engine that forms an image on transfer paper based on image data.

  The above operation is an operation for copying an image on one side of a sheet in a normal mode. However, when copying an image on both sides of a transfer sheet in a duplex mode, one of the paper feed trays 113 to 115 is used. The transfer paper that has been fed and has an image formed thereon as described above is switched by the paper discharge unit 122 to the double-sided paper feed path 124 side instead of the paper discharge tray 123 side, and is switched back by the reversing unit 125. The front and back sides are reversed and conveyed to the duplex conveying unit 126.

  The transfer paper transported to the double-sided transport unit 126 is transported to the vertical transport unit 116 by the double-sided transport unit 126, transported to a position where it abuts on the photoconductor 117 by the vertical transport unit 116, and on the photoconductor 117 as described above. The toner image formed on the back surface is transferred to the back surface and the toner image is fixed by the fixing device 121, whereby double-sided copying is performed. This double-sided copy is discharged to the paper discharge tray 123 by the paper discharge unit 122.

  Further, when the transfer paper is reversed and discharged, the transfer paper that is switched back by the reversing unit 125 and turned upside down is not conveyed to the duplex conveying unit 126 but is discharged via the reverse discharge conveyance path 127. The paper is discharged to the paper discharge tray 123 by the unit 122.

  In the print mode, image data from the outside is input to the writing unit 118 instead of the image data from the image processing means, and an image is formed on the transfer paper by the printer engine. Further, in the facsimile mode, the image data from the image reading means is transmitted to the other party by a facsimile transmission / reception unit (not shown), and the image data from the other party is received by the facsimile transmission / reception unit, instead of the image data from the image processing means. By inputting the data to the writing unit 118, an image is formed on the transfer paper by the printer engine described above.

  Next, a configuration example of the fixing device 121 will be described with reference to FIG. FIG. 2 is a front view illustrating a schematic configuration example of the fixing device 121. The fixing device 121 of the present embodiment is configured as an induction heating type fixing device. First, a fixing roller (second support roller) for heat-dissolving the toner on the transfer paper on which the toner has been transferred and fixing it onto the transfer paper in the same way as the normal halogen heater method, etc. 201 and a pressure roller 202 disposed opposite to the fixing roller 201 to apply pressure to the transfer paper to fix the toner. In addition, a heating roller (first support roller) 203 is provided at a position separated from the fixing roller 201, and a fixing belt (heat resistant belt) 204 is passed between the heating roller 203 and the fixing roller 201. Has been. The fixing belt 204 is a rotating member in a heated member for fixing that is induction-heated by an exciting coil (hereinafter also referred to as an IH coil) 205, and includes a heated metal portion (metal conductor) and a non-thermally conductive portion. It consists of several layers. The exciting coil 205 as induction heating means is for inductively heating the fixing belt 204 by eddy current. In this embodiment, the exciting coil 205 is an external heating method and has a shape that covers the outer peripheral surface of the heating roller 203 part about a half circumference. The substrate 206 has a structure in which a coil is wound in a spiral shape. Such an exciting coil 205 is energized with a current having an arbitrary frequency characteristic by an inverter circuit, which will be described later, and an eddy current flows through the heating roller 203 by receiving a magnetic flux generated by the current and is heated. The heat of the heating roller 203 is transmitted to the rotating fixing belt 204, and the heat and the nip pressure of the fixing roller 201 and the pressure roller 202 cause the heat on the transfer paper to move between the fixing roller 201 and the pressure roller 202 in the rotation direction. The toner is fixed on the transfer paper.

  In addition, the temperature of the fixing belt 204 is always monitored by a thermistor (temperature sensor) 207 that is in close proximity. If the temperature is lower than the control temperature, the current supply to the IH coil 205 is continued, and if higher, the supply is stopped. Temperature control is performed by a main body control circuit, which will be described later, but a safety device that directly shuts off the power supply by the thermostat 208 is mounted when the temperature becomes too high due to control failure.

  The fixing roller 201 is rotationally driven by a fixing motor (rotation drive source) 209, and the fixing belt 204 is moved and rotated by its power. The heating roller 203 is a driven roller that rotates by being suspended by the movement of the fixing belt 204.

  Further, an encoder (rotation detection sensor) 210 for detecting that the fixing belt 204 is rotating is provided on the shaft of the heating roller 203, and the fixing roller 201 is rotated despite the rotation. When the heating roller 203 does not rotate, it is determined that the belt has run out or the belt has slipped, and the operation of the inverter circuit is interrupted to prevent burnout due to an abnormal belt temperature rise in the excitation coil 205. .

  However, the induction heating type fixing device 121 is not limited to the external heating method as shown in the figure, and may be, for example, an internal heating method of a type in which an exciting coil is built in a fixing roller (patent). It can be applied to various methods shown in documents 1 to 4).

  Next, a configuration example of a control system for the fixing belt 204, the exciting coil 205, the thermistor 207, etc., that is, a fixing control device will be described with reference to a schematic block diagram shown in FIG. The fixing control board 301 is in charge of controlling the induction heating type fixing device 121 using the exciting coil 205. A CPU 302 mounted on the fixing control board 301 and responsible for the entire fixing control performs temperature control, abnormality detection, drive control, and the like by a program written in a built-in ROM. The CPU 302 also includes a RAM that stores all control data. These ROM and RAM may be external elements.

  The CPU 302 can always obtain the temperature of the fixing belt 204 by the thermistor 207 via the A / D converter 303. Further, the CPU 302 can recognize the rotation state of the heating roller 203 by obtaining a signal from the encoder 210 via the I / O driver 304. Further, the CPU 302 can perform ON / OFF control of the fixing motor 209 that rotates the fixing roller 201 via the I / O driver 305. On the other hand, the CPU 302 generates a necessary pulse through the PWM control circuit 306, and an inverter circuit 307 as an excitation drive circuit supplies a pulse current to the induction coil 205 in conjunction with the pulse, and induces an induction phenomenon in the induction coil 205. It can be raised and heated. That is, the inverter circuit 307 performs full-wave rectification of the AC power supply, and then supplies a current that is high-frequency switched by a switching control element such as an IGBT or FET as a coil current to the exciting coil 205 and a capacitor (not shown) to resonate. An AC magnetic field is generated and the fixing belt 204 is heated by eddy current.

  The CPU 302 controls the temperature of the fixing belt 204 by the thermistor 207, and controls the drive and stop operations of the inverter circuit 307 through the PWM control circuit 306 to perform control to maintain the necessary temperature. However, when the fixing belt 204 becomes abnormal due to an abnormal state such as a failure, the current supply is cut off by the adjacent thermostat 208. The thermostat 208 is selected so that the fixing device does not cause smoke or fire due to an abnormally high temperature.

  The energization path is set so that AC supply to the inverter circuit 307 is performed via the relay contact 308a of the relay 308. The relay contact 308a is normally closed and is configured to be forcibly opened (relay off) by energization control of the relay coil 308b by the CPU 302.

  In such a configuration, first, in FIG. 4, a fixing motor 209 that rotationally drives the fixing roller 201, an encoder 210 that monitors the rotation of the heating roller 203, an inverter circuit 307 that supplies a pulse current to the induction coil 205, and the fixing belt 204. 6 shows a time chart of each normal signal waveform of the thermistor 207 for monitoring the temperature of.

  At the same time as the fixing motor 209 is turned ON, the inverter circuit 307 generates a pulse current, and the thermistor 207 detects the temperature rise gradually. When the thermistor 207 reaches the target temperature, the inverter circuit 307 stops generating the pulse current, but the rotation of the fixing motor 209 and the pulse detection of the encoder 210 are continued. When it is detected that the thermistor 207 has dropped to a certain temperature, the inverter circuit 307 generates a pulse current again and supplies it to the exciting coil 205. As a result, the temperature detected by the thermistor 207 starts to rise again. By repeating this, the fixing belt 204 is always controlled at a temperature close to the target temperature. Then, at the same time as the fixing motor 209 is turned off, the generation of the pulse current of the inverter circuit 307 is also stopped, and the encoder 210 does not receive a pulse. Further, the detection output of the thermistor 207 also becomes data in which the temperature is gradually lowered.

  On the other hand, in the present embodiment, as an example of particular attention, for example, FIG. 5 shows a time chart example when the inverter circuit 307 causes an abnormal operation when the fixing motor 209 is not ON. That is, the inverter circuit 307 is in a runaway state and the inverter circuit 307 generates a pulse current in a state where the fixing motor 209 is not turned on, so that the fixing belt 204 starts to be heated. Naturally, the encoder 210 does not detect a pulse. When the fixing device abnormality occurs such that the inverter circuit 307 becomes uncontrollable in this way, there is a concern that the fixing belt 204 may rise above the target temperature. This is because only one portion of the fixing belt 204 is heated at a stretch, and the fixing belt 204 runs out of belt due to a local abnormal temperature rise, permanent deformation according to the shape of the heating roller 203, smoke generation, ignition, etc. It can happen.

  In order to avoid such a state, in this embodiment, the fixing motor 209 is forcibly turned on and the fixing belt 204 is rotationally moved to cause an abnormality due to induction heating in the stopped state as described above. To avoid. The time chart shows that the temperature of the fixing belt 204 gradually decreases as the fixing belt 204 is rotated.

  However, since such a countermeasure is temporary and not a fundamental countermeasure, in the present embodiment, when such an abnormality occurs, the relay coil 308b is normally closed in parallel with the above countermeasure. By forcibly opening the relay contact 308a, the power supply to the inverter circuit 307 is cut off, thereby avoiding the expansion and continuation of the abnormal state.

  An example of operation control during such an abnormality executed by the CPU 302 will be described with reference to a schematic flowchart shown in FIG. First, the temperature of the fixing belt 204 acquired through the thermistor 207 is constantly monitored, and it is checked whether or not this temperature exceeds the target temperature (step S1). Even when the thermistor temperature exceeds the target temperature (Y in S1), if there is a pulse signal from the encoder 210 and it is detected that the heating roller 203 and therefore the fixing belt 204 are rotating, (Y in S2), the normal induction heating control operation as described in FIG. 4 is executed (S3). On the other hand, when the thermistor temperature exceeds the target temperature (Y in S1), if the pulse signal from the encoder 210 is not detected and it is detected that the fixing belt 204 is stopped (N in S2), the present embodiment is performed. In this manner, it is determined that the fixing device 121 is abnormal while the fixing motor 209 to be controlled is stopped (S4). The processes in steps S1, S2, and S4 are executed as a function of the fixing device abnormality detection unit 309. When the abnormality is determined, the fixing motor 209 is forcibly turned on immediately (S5), and the heating roller 203, and thus the fixing belt 204, is rotated. As a result, even if the inverter circuit 307 runs away and the fixing belt 204 is subjected to induction heating by the excitation coil 205, the operation is not stopped but is the same as in normal operation. Therefore, at least a problem in the case of induction heating in the stopped state is avoided. Is done. The process of step S5 is executed as a function of the abnormal time control means.

  In parallel with the turning on of the fixing motor 209, the normally closed relay contact 308a is forcibly opened by energizing the relay coil 308b with an abnormality signal from the fixing device abnormality detecting means 309 (see FIG. 3) ( The relay is turned off (S6), and the power supply to the inverter circuit 307 is cut off, thereby implementing a fundamental safety measure for avoiding the expansion and continuation of the abnormal state. The processing in step S6 is also executed as a function of the abnormality control means.

  Thereafter, when the thermistor temperature (the temperature of the fixing belt 204) detected by the thermistor 207 decreases to a predetermined value or less with the passage of time (Y in S7), the fixing motor 209 is turned off (S8), and the heating roller 203 and accordingly. The processing is ended by stopping the fixing belt 204.

  By the way, in the present embodiment, when an abnormality of the fixing device 121 is detected while the fixing motor 209 is stopped (for example, a high temperature abnormality due to a runaway of the inverter circuit 307 or the like), there is also a function to notify the user to that effect. This point will be described with reference to a schematic block diagram shown in FIG. FIG. 7 shows a schematic configuration example on the side of the main control unit 402 mounted on the main body CPU 401 that is responsible for the control of the entire image forming apparatus. The main body CPU 401 has a network I / F 407 for connection to a network environment such as a memory 403 such as a ROM and a RAM used for programs and operations, a serial communication I / F 404, an external computer 405, a network server 406, and the like. Etc. are connected. The LCD 409 functioning as a notification unit of the operation control unit 408 in the image forming apparatus is connected to the main body CPU 401 via the LCD driver 410 and the serial communication I / F 404. On the other hand, the operation control unit 408 is also provided with an LED 411 that functions as a notification unit, and is connected to the main body CPU 401 via an LED driver 412 and an I / O control unit 413. Further, in relation to the above-described fixing control board 301 side, for example, the functional part of the fixing device abnormality detecting means 309 executed by the CPU 302 is connected to the main body CPU 401, and the above-described abnormal signal is notified to the main body CPU 401. It is configured as follows.

  Therefore, in the process of step S6 described with reference to FIG. 6, for example, an error signal is notified from the CPU 302 (fixing device abnormality detecting unit 309) side to the main body CPU 401, thereby displaying an error display on the LCD 409 and an error warning by blinking the LED 411. Thus, the user is notified of the occurrence of an abnormal situation. As a result, the user can take appropriate measures such as inspection of the fixing device 121, which is a more reliable and fundamental safety measure.

  For such error notification, the user may be away from the image forming apparatus. Therefore, the main body CPU 401 notifies the network server 406 of an abnormal signal through the network I / F 407, and this network server 406. Thus, it is preferable to notify the error on the screen of the computer 405 by distributing the abnormality signal to the computer 405 which is a terminal used by the user. According to this, even when the user is away from the image forming apparatus, it is possible to notify the user of the abnormality through the network and to make the user take appropriate measures such as checking the fixing device. This is a more reliable safety measure.

1 is a schematic front view illustrating an example of an electrophotographic image forming apparatus to which the present invention is applied. FIG. 3 is a front view illustrating a schematic configuration example of a fixing device. 2 is a schematic block diagram illustrating a configuration example of a fixing control device. FIG. It is a time chart which shows each signal waveform example at the time of normal operation. It is a time chart which shows each signal waveform example including the example of operation control at the time of abnormality. It is a schematic flowchart which shows the example of operation control. It is a schematic block diagram which shows the structural example by the side of a main control part.

Explanation of symbols

117 photoconductor 121 fixing device 201 second support roller, fixing member to be heated 203 first supporting roller, fixing member to be heated 204 heat resistant belt, fixing member to be heated, rotating member 205 induction coil, induction heating means 207 Temperature sensor 209 Rotation drive source 210 Rotation detection means 307 Inverter circuit, induction heating circuit 308 Relay 309 Fixing device abnormality detection means

Claims (10)

A fixing member to be heated including at least a rotating member that is driven to rotate;
A rotation drive source for rotating the rotating member;
Induction heating means for induction heating the heated member for fixing;
An induction heating circuit for driving the induction heating means;
Fixing device abnormality detecting means for detecting presence or absence of abnormality of the fixing device while the rotation drive source is stopped;
An abnormality control means for forcibly rotating the rotating member by the rotation drive source when an abnormality is detected by the fixing device abnormality detecting means;
A fixing control device. A rotation detection sensor for detecting the rotation of the rotating body;
The fixing control device according to claim 1, wherein the fixing device abnormality detection unit determines that the rotation drive source is stopped based on an output of the rotation detection sensor. A temperature sensor for detecting the temperature of the fixing member to be heated;
3. The fixing control device according to claim 1, wherein the fixing device abnormality detecting unit detects an abnormality of the fixing device when a temperature of the heated member for fixing detected by the temperature sensor exceeds a predetermined value.   4. The fixing control device according to claim 1, wherein the induction heating unit is an excitation coil, and the induction heating circuit is an inverter circuit that supplies a high-frequency current to the excitation coil. 5.   At least a heat-resistant belt as the rotating member, a first support roller inscribed in the heat-resistant belt, and a second support for rotatably supporting the heat-resistant belt between the first support roller 5. The apparatus according to claim 1, further comprising a roller as the member to be heated for fixing, wherein at least one of the first support roller and the heat-resistant belt is induction-heated by the induction heating unit. Fixing control device. A relay provided in the energization path for the induction heating circuit to intermittently supply power to the induction heating circuit;
The abnormality control means forcibly rotates the rotating member by the rotation drive source when the abnormality is detected by the fixing device abnormality detection means, and turns off the relay to cut off the power supply to the induction heating circuit. The fixing control device according to any one of claims 1 to 5.   The fixing control device according to claim 1, wherein the abnormality control unit causes the notification unit to notify an error when an abnormality is detected by the fixing device abnormality detection unit.   2. The abnormality control unit, when an abnormality is detected by the fixing device abnormality detecting unit, causes error information to be distributed to other terminals through a network to which an image forming apparatus including the fixing device is connected. The fixing control device according to any one of 7. A printer including a fixing device having a heated member for fixing heated by induction heating, a photoconductor, and other electrophotographic process members;
The fixing control device according to claim 1, wherein the fixing heated member is controlled.
An image forming apparatus comprising: A fixing member to be heated including at least a rotating member that is driven to rotate, a rotation driving source that rotates the rotating member, induction heating means that electromagnetically heats the fixing member to be heated, and driving the induction heating means A fixing control method by a fixing control device comprising an induction heating circuit,
A fixing device abnormality detection step of detecting whether or not the fixing device is abnormal while the rotation drive source is stopped;
An abnormality control step of forcibly rotating the rotating member by the rotation drive source when an abnormality is detected by the fixing device abnormality detecting step;
A fixing control method comprising:

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