JP2010271542A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-reliability image forming apparatus which can prevent misdetections as to whether an apparatus is in an abnormal state. <P>SOLUTION: The image forming apparatus includes a fixing device 10; a heat source 103 for heating the heat roller 101 of the fixing device 10; a thermistor 104 for detecting the temperature of the heat roller 101; a control device 109 for controlling the heat source 103 so that the temperature of the heat roller 101 has a temperature corresponding to the thickness of paper; and a paper-jamming detecting device 20 for detecting a paper jamming. Then, based on a jam signal SIG2, which is output from the paper-jamming detecting device 20 and indicates the occurrence of a paper jamming, the image forming apparatus determines whether to perform the operation of detecting an abnormal state of a device, such as, a CPU 110. In addition, based on a temperature signal SIG1, which is output from the thermistor 104 and indicates the temperature of the heat roller 101, and a preset abnormal temperature value, the image forming apparatus detects an abnormal state of a device, such as CPU 110, when the temperature signal SIG1 is equal to or higher than the abnormal temperature value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus using, for example, an electrophotographic system.

  Conventionally, as an image forming apparatus using an electrophotographic system, there is one disclosed in Japanese Patent Application Laid-Open No. 2007-133247 (Patent Document 1). The image forming apparatus includes a fixing device that fixes an image on a sheet. The fixing device includes a fixing roller having a built-in heating device and a pressure roller that presses the sheet against the fixing roller.

  In other image forming apparatuses, some devices have been devised to increase the speed of temperature increase of the fixing roller in order to save energy and reduce waiting time during printing. In this case, if the control device for controlling the temperature of the fixing roller breaks down, there is a concern that the fixing roller may be melted and destroyed or a fire and smoke accident may occur. For this reason, it is detected whether or not the temperature of the fixing roller has risen abnormally. When it is detected that the temperature of the fixing roller is abnormally high, the power supply to the heating device that heats the fixing roller is cut off.

  In detecting whether or not the temperature of the fixing roller has risen abnormally, the temperature at which the fixing roller and its surroundings are not melted and damaged is used as a threshold value. When the temperature of the fixing roller exceeds the threshold value, the temperature of the fixing roller is Suppose it is abnormally high. When the temperature of the fixing roller becomes equal to or higher than the threshold value, an error notification indicating that the control device is malfunctioning is performed to alert the user or service person.

  Other image forming apparatuses can print on various types of paper such as plain paper and cardboard. When printing on thick paper, this image forming apparatus secures the fixing performance by lowering the transport speed of thick paper from the transport speed of other paper. Among image forming apparatuses having a constant sheet conveyance speed, there is an apparatus that sets the temperature of the fixing roller when printing thick paper to be higher than the temperature of the fixing roller when printing other sheets.

  As can be seen from the above, the fixing device of the image forming apparatus rises in temperature when the heating device heats the fixing roller or when heat is not removed from the heating device after the heating of the heating device is completed. . The case where the heat is not taken away from the heating device is when the printing is finished and when the heat balance of the fixing device is lost at the time of abnormal stop due to paper jam or the like.

  Therefore, in an image forming apparatus in which the temperature of the fixing roller when printing thick paper is set higher than the temperature of the fixing roller when printing other paper, the temperature of the fixing roller rises when paper jam occurs. Will be over the threshold.

  As a result, there arises a problem that the control device for controlling the heating device is erroneously detected as having failed even though the control device has not failed.

JP 2007-133247 A

  Accordingly, an object of the present invention is to provide a highly reliable image forming apparatus capable of preventing erroneous detection as to whether or not the apparatus is abnormal.

  In an electrophotographic apparatus that melts and fixes toner, a circuit that controls a heating source (infrared heater or induction heating device) for melting the toner, or a case where control of this circuit becomes impossible Equipped with a safety switch such as a thermal switch or relay that cuts off the current to the heating source.

  The safety switch is set so as to eliminate smoke and ignition due to heating of the heating source. However, when the safety switch is activated, there are cases where the resin parts constituting the fixing device melt. If the resin parts are melted, a strange odor may be generated or the fixing device or the like may malfunction. For this reason, before the safety switch is activated, as a protection means at a level that does not cause a problem for the user, the abnormal temperature of the fixing device is detected, the power supply line to the heating source is shut off, and the operation panel Or, abnormal display is performed on the display of a PC (personal computer).

  The detection of the abnormal temperature of the fixing device needs to be detected as soon as possible so as not to damage the device. Therefore, it is determined that the temperature of the fixing device is as low as possible and the temperature of the fixing device is abnormal. There is a need.

  When performing normal printing operations, the temperature of the fixing device does not rise above the abnormal temperature. However, when a paper jam occurs, the paper is used to minimize damage to the device due to the paper jam. Control is performed to stop the conveyance immediately. When the conveyance of the paper is stopped, the supply of energy to a heating source such as a heater lamp is stopped by the control, but the temperature of the fixing device rises above the abnormal temperature by stopping the discharge of heat by the paper. End up. In this case, the circuit for controlling the heating source and the control of this circuit are normal, but an abnormality is displayed on the operation panel or the like.

  In such a case, it is possible to prevent erroneous detection and reduce useless downtime by recognizing that thick paper is being printed and recognizing a situation where the paper is jammed.

That is, the image forming apparatus of the present invention is
A fixing device that includes a fixing roller and a pressure roller that is rotatable in a state in which the fixing roller is pressed, and fixes the image on the recording medium;
A heating device for heating the fixing roller;
A temperature detecting device for detecting the temperature of the fixing roller;
A control device for controlling the heating device such that the temperature of the fixing roller is a temperature corresponding to the thickness of the recording medium;
A clogging detection device for detecting clogging of the recording medium;
Based on the presence or absence of a clogging signal output from the clogging detection device and indicating that the recording medium is clogged, it is determined whether or not to perform an abnormality detection operation of the control device, and the temperature detection An abnormality of the control device is detected when the temperature signal is equal to or higher than the abnormal temperature value based on a temperature signal output from the apparatus and indicating the temperature of the fixing roller and a preset abnormal temperature value. And an abnormality detection unit.

  According to the image forming apparatus having the above configuration, the abnormality detection unit outputs an abnormal temperature based on a temperature signal output from the temperature detection device and indicating the temperature of the fixing roller and a preset abnormal temperature value. When the value is greater than or equal to the value, an abnormality of the control device is detected. Further, the abnormality detection unit determines whether or not to perform an abnormality detection operation of the control device based on the presence or absence of a clogging signal that is output from the clogging detection device and indicates that the recording medium is clogged. Therefore, it is possible to prevent erroneous detection of an abnormality of the control device due to the clogging of the recording medium.

In the image forming apparatus of one embodiment,
The above abnormal temperature value is
A first value used when the recording medium is plain paper;
And a second value used when the recording medium is thick paper thicker than the plain paper.

  According to the image forming apparatus of the embodiment, the abnormal temperature value includes the first value used when the recording medium is plain paper and the second value used when the recording medium is thick paper. Whether the medium is plain paper or thick paper, it is possible to accurately detect abnormality of the control device.

  By the way, the heat capacity of the thick paper is larger than the heat capacity of plain paper, so that the temperature for melting the toner on the thick paper and fixing it to the thick paper can be obtained only by giving the same amount of heat to the plain paper. Absent. For this reason, it is preferable to give the cardboard a heat amount larger than that applied to the plain paper.

  Therefore, from the viewpoint of increasing the accuracy of detection of abnormality of the control device, the second value used when the recording medium is thick paper is made larger than the first value used when the recording medium is plain paper. Is preferred.

In the image forming apparatus of one embodiment,
The abnormal temperature value is higher when the recording medium is clogged than when the recording medium is not clogged.

  According to the image forming apparatus of the above embodiment, the abnormal temperature value is higher when the recording medium is clogged than when the recording medium is not clogged. It is possible to reliably prevent erroneous detection of an abnormality in the control device.

In the image forming apparatus of one embodiment,
The abnormality detection unit detects an abnormality of the control device based on the temperature of the fixing roller indicated by the temperature signal when a preset time has elapsed after receiving the clogging signal.

  According to the image forming apparatus of the above-described embodiment, the abnormality detection unit is configured to control the control device based on the temperature of the fixing roller indicated by the temperature signal when a preset time has elapsed after receiving the clogging signal. Since the abnormality is detected, the time can be shortened and the time required for detecting the abnormality of the control device can be shortened.

In the image forming apparatus of one embodiment,
The abnormality detection unit does not perform the abnormality detection operation of the control device until a preset time elapses after receiving the clogging signal.

  According to the image forming apparatus of the above embodiment, the abnormality detection unit does not perform the abnormality detection operation of the control device until a preset time elapses after receiving the clogging signal. False detection can be reduced.

In the image forming apparatus of one embodiment,
A blower that sends cooling air to the fixing device when the recording medium is jammed is provided.

  According to the image forming apparatus of the above-described embodiment, when the recording medium is clogged, the air blowing device sends cooling air to the fixing device, so that an increase in the temperature of the fixing roller can be suppressed.

  Accordingly, it is possible to prevent the temperature of the fixing roller from rising to an abnormal temperature value, thereby preventing erroneous detection of an abnormality in the control device.

  According to the image forming apparatus of the present invention, the abnormality detection unit performs an abnormality detection operation of the control device based on the presence or absence of a clogging signal output from the clogging detection device and indicating that the recording medium is clogged. Since it is determined whether or not to perform, it is possible to prevent erroneous detection of an abnormality of the control device due to the clogging of the recording medium.

FIG. 1 is a schematic configuration diagram of a color image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of a fixing device according to an embodiment of the present invention. FIG. 3 is another schematic configuration diagram of the fixing device. FIG. 4 is a graph of the change over time in the temperature of the heat roller during printing of thick paper. FIG. 5 is a graph of the change over time in the temperature of the heat roller during printing of thick paper. FIG. 6 is a graph of the change over time in the temperature of the heat roller during printing of thick paper. FIG. 7 is a graph of the change over time in the temperature of the heat roller during printing of thick paper. FIG. 8 is a flowchart of an example of control of the color image forming apparatus. FIG. 9 is a flowchart of another control example of the color image forming apparatus. FIG. 10 is a flowchart of another control example of the color image forming apparatus. FIG. 11 is a flowchart of another control example of the color image forming apparatus.

  An image forming apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a tandem type color image forming apparatus according to an embodiment of the present invention.

  In FIG. 1, 1Y, 1M, 1C, and 1K are toner cartridges that store toner, 2Y, 2M, 2C, and 2K are photosensitive members, 3Y, 3M, 3C, and 3K are developing units, and 4Y, 4M, 4C, and 4K are cleaners. Units 5 are laser exposure units for forming electrostatic latent images on the photoreceptors 2Y, 2M, 2C, and 2K, 6 is a paper cassette, 7 is a feed roller, 8 is a pair of transport rollers, 9 is a transport path, and 10 is a paper P Fixing device for fusing and fixing the toner above, 11 is a blower, 12 is a carry-out roller pair, 13 is an endless intermediate transfer member, 14 is a drive roller, 15 is a driven roller, 16Y, 16M, 16C, and 16K are primary transfer A roller, 17 is a secondary transfer roller for transferring the toner image on the endless intermediate transfer body 13 to the paper P, 18 is a main body casing, 19 is a discharge tray, and 20 is a paper jam detection for detecting a paper jam of the paper P. It is a device. The paper jam detection device 20 is an example of a jam detection device, and the paper P is an example of a recording medium.

  2 and 3 are schematic configuration diagrams of the fixing device 10.

  As shown in FIG. 2, the fixing device 10 includes a rotatable heat roller 101 and a pressure roller 102 that can rotate while being in pressure contact with the heat roller 101. The heat roller is an example of a fixing roller.

  The heat roller 101 incorporates a heating source 103 and melts the toner on the paper P from the conveyance path 9. The temperature of the outer peripheral surface of the heat roller 101 that contacts the paper P (hereinafter referred to as “temperature of the heat roller 101”) can be monitored by the thermistor 104. In addition, the thermal switch 105 prevents a fire in preparation for the case where the control of the heating source 103 becomes impossible. The heating source 103 is an example of a heating device, and the thermistor 104 is an example of a temperature detection device.

  As shown in FIG. 3, the heating source 103 is connected to a power plug 108 via a thermal switch 105, an energizing element 106, and a safety relay 107. The energization element 106 and the safety relay 107 are controlled by the control device 109. The control device 109 is an example of a control device.

  The control device 109 has a CPU (Central Processing Unit) 110, and the CPU 110 controls the energization element 106 to be turned on and off to control the temperature of the heat roller 101 to a target temperature. The target temperature is set based on the paper thickness information input by the user to the operation panel (not shown). For example, when the paper thickness is plain paper thickness, the target temperature is set to be relatively low, while when the paper thickness is thick paper thickness, the target temperature is relatively high. Set as follows. That is, the temperature of the heat roller 101 is changed according to the thickness of the paper P. In addition, a paper thickness detection device that detects the paper thickness of the paper P is installed, and the temperature of the fixing roller 101 is changed based on an output signal of the paper thickness detection device (a signal indicating the paper thickness of the paper P). May be. Here, the thick paper refers to paper thicker than the plain paper.

  Further, the control device 109 receives a temperature signal SIG1 indicating the temperature of the heat roller 101 from the thermistor 104, and a paper jam signal SIG2 indicating that the paper P is jammed from the paper jam detection device 20. Receive. Thus, the CPU 110 can perform control based on the temperature signal SIG1 and the paper jam signal SIG2. The paper jam signal SIG2 is an example of a jam signal.

  In addition, when the paper P is jammed, the control device 109 stops the conveyance of the paper P and stops the supply of power to the heating source 103. This stoppage of power supply is realized by cutting off the power supply path by the energization element 106 and the safety relay 107.

  Further, by stopping the conveyance of the paper P, the rotation of the heat roller 101 and the pressure roller 102 of the fixing device 10 is stopped. For this reason, the heat accumulated in the pressure roller 102 does not move to the outside by the paper P, and the temperature of the heat roller 101 rises. This increased value is constant depending on the heat capacity of the rollers, but when paper jams occur when printing thick paper, rather than when paper jams occur when printing plain paper, The temperature of the heat roller 101 after the rotation of the heat roller 101 and the pressure roller 102 is increased.

  FIG. 4 is a graph showing an example of a change over time in the temperature of the heat roller 101 when thick paper is used as the paper P. The time on the horizontal axis of the graph is the time that has elapsed since the printing of the cardboard started.

  In the example of FIG. 4, the temperature that was 215 ° C. has increased since t0 when the control device 109 receives the signal SIG2. Since this increase value is about 30 ° C., it exceeds a preset abnormal temperature value T1 (for example, 220 <T1 <240). For this reason, if the abnormality determination is performed based on the abnormal temperature value T1 from the time t0 when the control device 109 receives the signal SIG2 until t1 seconds (for example, about 120 seconds) have elapsed, the device such as the CPU 110 is abnormal. The probability of false detection is increased. The abnormal temperature value T1 is an example of a second value.

  Therefore, in the color image forming apparatus according to the present embodiment, an abnormality in an apparatus such as the CPU 110 (hereinafter referred to as “apparatus abnormality”) is performed until t1 seconds elapse from t0 when the control apparatus 109 receives the signal SIG2. Has control that does not perform presence / absence detection.

  The color image forming apparatus according to the present embodiment has high reliability because the power supply circuit to the heating source 103 has two systems of the energization element 106 and the safety relay 107. Further, in the color image forming apparatus of the present embodiment, even if a software bug of the CPU 110 that controls the energization element 106 and the safety relay 107 or a failure of an element on the board occurs, an event different from the software or the hardware circuit As a result, the safety of the thermal switch 105 is secured. Since it is such a color image forming apparatus, detection of apparatus abnormality also serves as protection of the heating source 103 when the control apparatus 109 fails, but t1 seconds have elapsed since t0 when the control apparatus 109 received the signal SIG2. Until then, the system that does not detect abnormality can be adopted.

  Hereinafter, a method in which the abnormality detection is not performed will be described with reference to the flowchart of FIG. Note that the flowchart of FIG. 8 shows processing performed when printing thick paper.

  In the above method, first, in step S1, an operation for detecting the presence or absence of an apparatus abnormality is performed. At this time, if the temperature of the heat roller 101 is equal to or higher than the abnormal temperature value T1, the CPU 110 displays an apparatus abnormality on the operation panel or the display of the PC. Here, the PC refers to a personal computer connected to the color image forming apparatus via a wired LAN (local area network) or a wireless LAN.

  Next, in step S2, it is determined whether a paper jam has occurred. If it is determined in step S2 that no paper jam has occurred, the process returns to step S1 and the operation for detecting whether there is a device abnormality is performed again. On the other hand, if it is determined in step S2 that a paper jam has occurred, the process proceeds to the next step S3.

  Next, in step S3, power supply to the heating source 103 and paper conveyance are stopped.

  Next, in step S4, it is determined whether t1 seconds have elapsed from t0 when the control device 109 receives the signal SIG2. This step S4 is repeated until it is determined that t1 seconds have elapsed from t0 when the control device 109 receives the signal SIG2. If it is determined in step S4 that t1 seconds have elapsed from t0 when the control device 109 receives the signal SIG2, the process returns to step S1 and the operation for detecting whether there is a device abnormality is performed again.

  Here, steps S1, S2, and S4 are examples of the abnormality detection unit.

  Thus, since the operation for detecting whether or not there is a device abnormality is not performed until t1 seconds elapse from t0 when the control device 109 receives the signal SIG2, erroneous detection of the device abnormality can be prevented.

  Further, when the paper P is plain paper, an operation for detecting whether there is an apparatus abnormality may be performed based on an abnormal temperature value lower than the abnormal temperature value T1. The abnormal temperature value lower than the abnormal temperature value T1 is an example of the first value.

  Further, as a method for preventing erroneous detection of the apparatus abnormality, a method as shown in FIG. 5 may be adopted. In FIG. 5, after the power supply to the heating source 103 and the sheet conveyance are stopped, the abnormality detection is continued, but the abnormal temperature value T2 higher by ΔT ° C. than the abnormal temperature value T1 (for example, 220 <T1 <240). Based on (for example, 240 <T1 <260), an operation for detecting presence / absence of an apparatus abnormality is performed. The abnormal temperature value T2 is an example of a second value.

  Hereinafter, a method using the abnormal temperature values T1 and T2 will be described with reference to the flowchart of FIG. Note that the flowchart of FIG. 9 shows processing performed when printing thick paper.

  In the above method, first, in step S11, an operation for detecting presence / absence of an apparatus abnormality is performed. At this time, if the temperature of the heat roller 101 is equal to or higher than the abnormal temperature value T1, the CPU 110 displays an apparatus abnormality on the operation panel or the display of the PC.

  Next, in step S12, it is determined whether a paper jam has occurred. If it is determined in step S12 that no paper jam has occurred, the process returns to step S11 and the operation for detecting the presence or absence of an apparatus abnormality is performed again. On the other hand, if it is determined in step S12 that a paper jam has occurred, the process proceeds to the next step S13.

  Next, in step S13, power supply to the heating source 103 and paper conveyance are stopped.

  Next, in step S14, the setting is changed so that the operation for detecting the presence or absence of an apparatus abnormality is performed based on the abnormal temperature value T2.

  Next, in step S15, an operation for detecting whether there is an apparatus abnormality is performed. At this time, if the temperature of the heat roller 101 is equal to or higher than the abnormal temperature value T2, the CPU 110 displays an apparatus abnormality on the operation panel or the display of the PC.

  Next, in step S16, it is determined whether t1 seconds (for example, about 120 seconds) have elapsed from t0 when the control device 109 receives the signal SIG2. In step S16, when it is determined that t1 seconds have not elapsed from t0 when the control device 109 receives the signal SIG2, the process returns to step S16, and the operation for detecting whether there is a device abnormality is performed again. On the other hand, if it is determined in step S16 that t1 seconds have elapsed from t0 when the control device 109 receives the signal SIG2, the process proceeds to the next step S17.

  Next, in step S17, the setting is changed so that the detection operation for the presence / absence of the device abnormality is performed based on the abnormal temperature value T1, and then the process returns to step S11 to perform the detection operation for the presence / absence of the device abnormality.

  Here, steps S11, S12, and S14 to S17 are an example of an abnormality detection unit.

  In this way, when thick paper is used as the paper P and a paper jam has occurred, the presence / absence of device abnormality is determined based on the abnormal temperature value T2 that is higher by ΔT ° C. (for example, about 20 ° C.) than the abnormal temperature value T1. Since the detection operation is performed, it is possible to reliably prevent erroneous detection of an apparatus abnormality.

  Further, even after the power supply to the heating source 103 and the sheet conveyance are stopped, the detection operation for the presence or absence of the apparatus abnormality is continued, so that the safety can be increased compared with the method of FIG. .

  Further, as a method for preventing erroneous detection of the apparatus abnormality, a method as shown in FIG. 6 may be adopted. In FIG. 6, instead of the temperature table of FIG. 5, the temperature increase rate of the heat roller 101 during t2 seconds (about 30 seconds) is compared with the normal temperature increase rate examined in advance. Based on the result, an operation for detecting the presence or absence of an apparatus abnormality is performed.

  Hereinafter, a method using the temperature increase rate of the heat roller 101 will be described with reference to the flowchart of FIG. Note that the flowchart of FIG. 10 shows processing performed when printing thick paper.

  In the above method, first, in step S21, an operation for detecting the presence or absence of an apparatus abnormality is performed. At this time, if the temperature of the heat roller 101 is equal to or higher than the abnormal temperature value T1 (for example, 220 <T1 <240), the CPU 110 displays an apparatus abnormality on the operation panel or the display of the PC.

  Next, in step S22, it is determined whether a paper jam has occurred. If it is determined in step S22 that no paper jam has occurred, the process returns to step S21, and the operation for detecting the presence or absence of an apparatus abnormality is performed again. On the other hand, if it is determined in step S22 that a paper jam has occurred, the process proceeds to the next step S23.

  Next, in step S23, power supply to the heating source 103 and paper conveyance are stopped.

  Next, abnormality detection is performed at step S24. This abnormality detection is performed by calculating the temperature rise rate of the heat roller 101 from t0 to t2 seconds after the control device 109 receives the signal SIG2, and the temperature rise rate and the normal temperature rise rate checked in advance. It is done by comparing. At this time, if the temperature increase rate of the heat roller 101 exceeds the normal temperature increase rate checked in advance, the CPU 110 displays an apparatus abnormality on the operation panel or the display of the PC.

  Next, in step S25, it is determined whether t1 seconds (for example, about 120 seconds) have elapsed from t0 when the control device 109 receives the signal SIG2. This step S25 is repeated until it is determined that t1 seconds have elapsed since the control device 109 received the paper jam signal SIG2 from the paper jam detection device 20. If it is determined in step S25 that t1 seconds have elapsed since the control device 109 received the paper jam signal SIG2 from the paper jam detection device 20, the process returns to step S21, and an operation for detecting whether there is an apparatus abnormality is performed again.

  Here, steps S21, S22, and S24 are an example of an abnormality detection unit.

  Thus, by comparing the temperature increase rate of the heat roller 101 between t0 and t2 seconds after the control device 109 receives the signal SIG2, the normal temperature increase rate examined in advance is compared. An apparatus abnormality can be detected in a shorter time than the method of FIG.

  Further, in the failure mode in which power supply to the heating source 103 is kept, the temperature rise rate of the heat roller 101 between t0 and t2 seconds after the control device 109 receives the signal SIG2 is examined in advance. It will exceed the normal rate of temperature rise.

  Therefore, the temperature rise rate of the heat roller 101 can be detected by comparing it with a normal temperature rise rate that has been examined in advance, so that a failure that keeps supplying power to the heating source 103 can be detected.

  In the flowchart of FIG. 10, after the supply of power to the heating source 103 and the stop of paper conveyance, the temperature rise rate of the heat roller 101 is compared with the normal temperature rise rate checked in advance once. This comparison may be performed a plurality of times at preset time intervals.

  Further, as a method for preventing erroneous detection of the apparatus abnormality, a method as shown in FIG. 7 may be adopted. In FIG. 7, power supply to the heating source 103, paper conveyance, and the blowing device 11 are stopped, and then cooling air is sent from the blowing device 11 to the fixing device 10 again.

  Hereinafter, a method of sending cooling air from the blower 11 to the fixing device 10 will be described with reference to the flowchart of FIG. Note that the flowchart in FIG. 11 shows processing performed when printing thick paper.

  In the above method, first, in step S31, an operation for detecting presence / absence of an apparatus abnormality is performed. At this time, if the temperature of the heat roller 101 is equal to or higher than the abnormal temperature value T1 (for example, 220 <T1 <240), the CPU 110 displays an apparatus abnormality on the operation panel or the display of the PC.

  Next, in step S32, it is determined whether or not a paper jam has occurred. If it is determined in step S32 that a paper jam has not occurred, the process returns to step S31, and the operation for detecting whether there is a device abnormality is performed again. On the other hand, if it is determined in step S32 that a paper jam has occurred, the process proceeds to the next step S33.

  Next, in step S33, power supply to the heat source 103, paper conveyance, and the blower 11 are stopped.

  Next, in step S <b> 34, the air blower 11 is turned on, and cooling air is sent from the air blower 11 to the fixing device 10.

  Next, in step S35, an operation for detecting whether there is an apparatus abnormality is performed. At this time, if the temperature of the heat roller 101 is equal to or higher than the abnormal temperature value T1, the CPU 110 displays an apparatus abnormality on the operation panel or the display of the PC.

  Next, in step S36, it is determined whether t1 seconds (for example, about 120 seconds) have elapsed from t0 when the control device 109 receives the signal SIG2. If it is determined in step S36 that t1 seconds have not elapsed from t0 when the control device 109 receives the signal SIG2, the process returns to step S35, and the operation for detecting whether there is a device abnormality is performed again. On the other hand, if it is determined in step S36 that t1 seconds have elapsed from t0 when the control device 109 receives the signal SIG2, the process proceeds to the next step S37.

  Next, in step S36, the air blower 11 is turned off, the supply of cooling air to the fixing device 10 is stopped, and then the process returns to step S31.

  Here, steps S31, S32, and S35 are an example of an abnormality detection unit.

  As described above, after the supply of power to the heating source 103 and the conveyance of the paper are stopped, the cooling air from the blower is supplied to the fixing device 10, so that if the device such as the CPU 110 is not abnormal, as shown in FIG. The temperature of the heat roller 101 is less than the abnormal temperature value T1.

  Therefore, it is possible to reliably prevent erroneous detection of the apparatus abnormality without changing the setting of the abnormal temperature value T1 after stopping the power supply to the heating source 103 and the sheet conveyance.

  In the above embodiment, the heating source 103 is arranged in the heat roller 101 and the heat roller 101 is heated by the heating source 103. However, the heating source is arranged in the heat roller 101 and the heating source is used for heating. The roller 101 may be heated.

  In the above embodiment, a belt may be disposed between the heat roller 101 and the pressure roller 102.

DESCRIPTION OF SYMBOLS 10 Fixing device 11 Blower device 20 Paper jam detection device 101 Heat roller 102 Pressure roller 103 Heat source 104 Thermistor 109 Control device SIG1 Temperature signal SIG2 Paper jam signal P Paper

Claims (6)

A fixing device that includes a fixing roller and a pressure roller that is rotatable in a state in which the fixing roller is pressed, and fixes the image on the recording medium;
A heating device for heating the fixing roller;
A temperature detecting device for detecting the temperature of the fixing roller;
A control device for controlling the heating device such that the temperature of the fixing roller is a temperature corresponding to the thickness of the recording medium;
A clogging detection device for detecting clogging of the recording medium;
Based on the presence or absence of a clogging signal output from the clogging detection device and indicating that the recording medium is clogged, it is determined whether or not to perform an abnormality detection operation of the control device, and the temperature detection An abnormality of the control device is detected when the temperature signal is equal to or higher than the abnormal temperature value based on a temperature signal output from the apparatus and indicating the temperature of the fixing roller and a preset abnormal temperature value. An image forming apparatus comprising: an abnormality detection unit. The image forming apparatus according to claim 1.
The above abnormal temperature value is
A first value used when the recording medium is plain paper;
And a second value used when the recording medium is thick paper thicker than the plain paper. The image forming apparatus according to claim 1, wherein
The image forming apparatus according to claim 1, wherein the abnormal temperature value is higher when the recording medium is clogged than when the recording medium is not clogged. The image forming apparatus according to claim 1, wherein
The abnormality detection unit detects an abnormality of the control device based on a temperature of the fixing roller indicated by the temperature signal when a preset time has elapsed after receiving the clogging signal. An image forming apparatus. The image forming apparatus according to claim 1, wherein
The image forming apparatus, wherein the abnormality detection unit does not perform an abnormality detection operation of the control device until a preset time elapses after receiving the clogging signal. In the image forming apparatus according to any one of claims 1 to 5,
An image forming apparatus comprising: a blower that sends cooling air to the fixing device when the recording medium is jammed.

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