JP2011090063A - Fixing device, image forming apparatus, method for controlling fixing heater, program, and recording medium - Google Patents

Abstract

A fixing device, an image forming apparatus, a fixing heater control method, and a program for reliably detecting a case where an application state to a heater becomes abnormal and stopping power supply to the heater to prevent deterioration of the fixing device. And a recording medium.
A fixing device includes a step-down unit that steps down a voltage applied to a fixing heater, a voltage detection unit that detects a heater applied voltage that is a voltage applied to the fixing heater, and a fixing heater. An abnormality detection unit 109 that compares a heater control signal for controlling a voltage applied to the heater and a heater application voltage detected by the voltage detection unit 107 to determine whether or not the application state to the fixing heater 253 is abnormal; A switch 10 that cuts off the application to the fixing heater 253 when the abnormality detection unit 109 determines that the application state to the fixing heater 253 is abnormal.
[Selection] Figure 4

Description

  The present invention relates to a fixing device that controls temperature of a fixing unit, an image forming apparatus, a fixing heater control method, a program, and a recording medium.

  In recent years, an image forming apparatus such as an electrophotographic printer provided with a fixing device including a fixing heater and a fixing heating roller has become widespread. In such an image forming apparatus, techniques such as shortening the warm-up time by supplying a large voltage to the fixing heater have already been proposed (for example, Patent Document 1 and Patent Document 2). However, when the fixing heating roller is excessively heated by the fixing heater, there is a problem that the temperature of the fixing heating roller becomes an abnormal temperature.

  In order to solve the above problem, a technique for performing temperature control has been proposed as a configuration as shown in FIG. In other words, the temperature of the fixing unit is monitored with a thermistor so that the temperature of the fixing unit becomes constant, and power supply to the fixing heater is an integral multiple of the half wavelength of the commercial power supply, with the half wavelength unit of the commercial power supply as the minimum unit. Thus, the control is performed by determining the duty of the energization time and the non-energization time per unit time of the temperature control. FIG. 12 shows operation waveforms when the duty to be applied to the fixing heater is determined based on the detected temperature of the fixing unit and the fixing heater is energized. However, the above-described method has a disadvantage that flicker and fine power control cannot be performed.

  Therefore, as shown in FIG. 13, it is proposed to drive the fixing heater by PWM. By PWM driving the fixing heater at a frequency higher than the commercial power supply frequency, flicker can be suppressed and fine power control can be performed. FIG. 14 shows a current waveform when the duty to be applied to the fixing heater is determined based on the result of detecting the temperature of the fixing unit and the fixing heater is energized.

  Further, in connection with the control of the voltage supplied to the fixing heater, a technique has been proposed in which a switching element is interposed in the power supply path to step down the power supply voltage of the commercial AC power supply and supply power to the fixing heater (for example, Patent Document 3). In this technique, the power supplied to the fixing heater is controlled by switching the switching element at a frequency higher than the frequency of the commercial AC power supply and controlling the duty ratio.

  However, with the above-described technique, it is only possible to detect the fixing temperature and stop the power supply to the fixing heater when the temperature becomes abnormal. That is, there is a problem that the abnormality of the apparatus cannot be detected until the temperature becomes abnormal for the fixing apparatus having a small capacity and rapidly rising. For this reason, even if an abnormality occurs in the apparatus, power is continuously supplied to the fixing heater for a while, so that the fixing heating roller becomes abnormally high temperature and the molding member of the fixing apparatus deteriorates. There was a problem of ending up.

  The present invention has been made in view of such circumstances, and reliably detects a case where an application state to the heater becomes abnormal, and stops power supply to the heater, thereby preventing deterioration of the fixing device. It is an object of the present invention to provide a fixing device, an image forming apparatus, a fixing heater control method, a program, and a recording medium.

  The fixing device according to the present invention includes a step-down means for stepping down a voltage applied to the fixing heater, a voltage detecting means for detecting a heater applied voltage that is a voltage applied to the fixing heater, and a voltage applied to the fixing heater. The heater control signal to be detected is compared with the heater applied voltage detected by the voltage detecting means, and an abnormality detecting means for judging whether or not the application state to the fixing heater is abnormal, and an application to the fixing heater by the abnormality detecting means. And a blocking means for blocking application to the fixing heater when it is determined that the state is abnormal.

  The image forming apparatus according to the present invention includes a control unit that outputs a heater control signal that controls a voltage applied to the fixing heater, a step-down unit that steps down the voltage applied to the fixing heater, and a voltage applied to the fixing heater. The voltage detection means for detecting a heater applied voltage, the heater control signal output by the control means and the heater applied voltage detected by the voltage detection means are compared, and whether or not the application state to the fixing heater is abnormal And an interruption detecting means for interrupting the application to the fixing heater when the abnormality detection means determines that the application state to the fixing heater is abnormal.

  The fixing heater control method of the present invention includes a step-down step for stepping down a voltage applied to the fixing heater, a voltage detection step for detecting a heater applied voltage that is a voltage applied to the fixing heater, and a voltage applied to the fixing heater. The heater control signal for controlling the heater and the heater applied voltage detected in the voltage detection step are compared to determine whether or not the application state to the fixing heater is abnormal, and to the fixing heater in the abnormality detection step And a blocking step for blocking the application to the fixing heater when it is determined that the application state is abnormal.

  The program of the present invention includes a process for stepping down the voltage applied to the fixing heater, a process for detecting a heater applied voltage that is a voltage applied to the fixing heater, and a heater control signal for controlling the voltage applied to the fixing heater. And the heater applied voltage to determine whether the application state to the fixing heater is abnormal or not, and if the application state to the fixing heater is determined to be abnormal, the application to the fixing heater And causing the computer to execute a process for shutting off.

  The recording medium of the present invention is a computer-readable recording medium on which the above program is recorded.

  According to the present invention, it is possible to reliably detect a case where an application state to the heater becomes abnormal, to stop power supply to the heater, and to prevent deterioration of the fixing device.

1 is a diagram illustrating a schematic configuration example of an image forming apparatus according to an embodiment. FIG. 3 is a diagram illustrating a schematic configuration example of a main part of a fixing device according to an exemplary embodiment. 1 is a block diagram illustrating a schematic functional configuration example of an image forming apparatus according to an embodiment. FIG. 4 is a diagram for explaining an example of a fixing heater driving circuit of the fixing device according to the embodiment. It is a figure which shows the example of a relationship between the heater applied voltage of the fixing device which concerns on this embodiment, and a heater voltage detection circuit output. It is a figure which shows the example of a relationship between the heater control signal and heater drive circuit output of the fixing device which concerns on this embodiment. 6 is a flowchart illustrating a flow of an example of heater power supply control operation of the fixing device according to the present exemplary embodiment. 1 is a block diagram illustrating a schematic functional configuration example of an image forming apparatus according to an embodiment. FIG. 4 is a diagram for explaining an example of a fixing heater driving circuit of the fixing device according to the embodiment. 6 is a flowchart illustrating a flow of an example of heater power supply control operation of the fixing device according to the present exemplary embodiment. It is a figure which shows the heater drive circuit of the fixing device relevant to this invention. It is a figure which shows the electric current waveform at the time of supplying with electricity to the fixing heater of the fixing device relevant to this invention. It is a figure which shows the heater drive circuit of the fixing device relevant to this invention. It is a figure which shows the electric current waveform at the time of supplying with electricity to the fixing heater of the fixing device relevant to this invention.

  Hereinafter, examples of embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 shows a schematic functional configuration example of an image forming apparatus according to the present embodiment. Here, a copying machine will be described as an example of the image forming apparatus, but the present invention is not limited to this.

  As shown in FIG. 1, a drum-shaped image carrier (hereinafter referred to as a photoconductor) 12 is provided in an image forming apparatus main body 100 according to the present embodiment. A charging device 13, a developing device 14, a transfer / conveying device 15, a cleaning device 16, a static eliminating device 17, and the like are disposed around the photoreceptor 12. Further, a laser writing device 18 is provided above each of these components. The laser writing device 18 includes a light source 20 such as a laser diode, a scanning rotary polygon mirror 21, a polygon motor 22, a scanning optical system 23 such as an fθ lens, and the like. On the left side of the cleaning device 16 in the figure, a fixing device 250, which will be described in detail later, is disposed. In the present exemplary embodiment, the image forming apparatus 100 is described with an example in which the photosensitive member 12 and one component provided around the photosensitive member 12 are provided. However, the present invention is not limited to this. For example, the image forming apparatus according to the present embodiment may be a tandem type color laser printer including a plurality of components provided on the photosensitive member and its periphery.

  In the image forming unit illustrated in FIG. 1, when a drum-shaped photoconductor 12, which is an example of an image carrier, rotates in the clockwise direction, the surface of the photoconductor is charged to a predetermined polarity by the charging device 13. The charged surface is irradiated with a light-modulated laser beam L emitted from a laser writing device 18 which is an example of an image forming unit, whereby an electrostatic latent image is formed on the surface of the photoreceptor.

  The electrostatic latent image is visualized as a toner image by the developing device 14, and the toner image is transferred onto the recording material fed by the paper feeding unit by the action of the transfer / conveyance device 15. Transfer residual toner adhering to the surface of the photoconductor after the toner image is transferred is removed by a cleaning brush or a cleaning blade provided in the cleaning device 16.

  In the paper feeding unit 43 located at the lower part of the image forming apparatus main body 100, the recording material P made of, for example, sheet-like transfer paper or resin sheet accommodated in the cassette 44 or the like is sent out by the rotation of the feeding roller 45. Then, the recording material P sent out by the paper feed roller 45 waits at the position of the registration roller pair 48 by the rotation of the conveyance roller pairs 74 and 37 and then transfers between the photosensitive member 12 and the transfer / conveyance device 15 at a predetermined timing. Here, as described above, the toner image on the photoreceptor 12 is transferred onto the recording material and carried as an unfixed image Ta. The recording material P onto which the toner image has been transferred is continuously conveyed to the fixing device 250 and fed into the nip portion between the fixing belt 251 and the pressure roller 256 that are in a pressure contact state. Then, the toner image Ta is fixed on the surface of the recording material P by fixing with the heating by the fixing belt 251 and the pressing force of the fixing belt 251 (fixing roller 252) and the pressure roller 256. The recording material P that has passed through the fixing device 250 is discharged onto a tray outside the apparatus.

  1 shows an example in which the image forming apparatus 100 includes the duplex unit 35, but it is not always necessary to include the duplex unit. When recording on the back side of the sheet using the duplex unit 35, after recording on one side, the sheet is conveyed to the duplex unit 35 through the reverse path 39, reversed there, and sent again below the photoreceptor 12. The image separately formed on the photoconductor 12 is similarly transferred to the back surface and then discharged onto the tray.

  A document reading device 30 is provided in the upper part of the image forming apparatus main body 100. The document reading device 30 includes a light source 31, a plurality of mirrors 32, an imaging lens 33, an image sensor 34 such as a CCD (Charge Coupled Device), and the like. Also provided is a known automatic document feeder (ADF) 41 that automatically conveys a sheet document to a document reading position, reads document information, and automatically discharges the document after reading from the document reading position. Yes.

  The document reading device 30 includes a light source (lamp) 31 that scans and irradiates a document on the document stacking table 40. Reflected light from the document obtained by irradiation of the lamp 31 is reflected by a plurality of mirrors 32 and is incident on an imaging lens 33. This light passes through the imaging lens 33 and enters the CCD 34 as a light receiver as image light. The CCD 34 converts the incident image light into a digital signal and outputs it. The output is subjected to necessary processing in the image processing unit in the image recording processing unit, and converted into a signal for image recording formation.

  A control unit (system controller) (not shown) mounted in the image forming apparatus main body 100 includes a CPU (Central Processing Unit), a ROM (Read-Only Memory), a RAM (Random Access Memory), and the like as is well known. Based on image information transmitted from a personal computer (not shown) or the like, a static elimination device (static elimination lamp) 17, a charging device (charging roller) 13, the optical writing unit 18, a developing device 14, a developing bias applying means, the supply A desired image forming operation is performed by controlling driving of the paper portion, transfer bias applying means, transfer roller, fixing heater, and the like.

  In addition, the control unit includes a rotation unit including a motor, each drive system of a transport mechanism, various sensors including a toner density sensor and a reflection density sensor, a data storage unit including a RAM and a ROM, an operation display including a touch panel, and the like. Etc. are connected, and these are controlled. Further, based on the detection result of the reference density toner image, process control for adjusting the bias voltage of the developing sleeve or the like to an appropriate one is also performed.

  FIG. 2 shows a schematic configuration example of the fixing device 250 according to the present embodiment. In the present exemplary embodiment, a fixing belt type fixing device will be described as an example, but the present invention is not limited to this.

  The fixing belt type fixing device 250 includes a fixing roller 252 positioned within the periphery of the fixing belt 251 as a fixing rotating body, and a fixing heating roller 254 that is a heated body including a heater 253 as a heating element therein. It is configured. The fixing heating roller 254 also serves as a tension roller, and is biased outward (upward in the drawing) by a tension spring 255 to apply tension to the fixing belt 251. A pressure roller 256 as a pressure rotator is disposed on the opposite side of the fixing belt peripheral circuit with respect to the fixing roller 252 with the fixing belt 251 interposed therebetween. Forming.

  As the fixing belt 251, for example, a belt whose surface is covered with a PFA tube can be used. As the fixing roller 252, for example, a foamed silicon rubber roller can be used. Note that aluminum can be used as the material of the fixing heating roller 254, but the material is not limited to this.

  Note that the heater 257 may be included in the pressure roller 256 as well. The heater 257 serves as a heating source during the fixing operation. The fixing device 250 according to the present embodiment includes a thermistor 254C that is a temperature sensor as a temperature detecting unit that faces the surface of the fixing belt 251 in a non-contact manner. The output of the heater 253 is controlled based on the detection result of the belt surface temperature by the thermistor 254C, and the temperature of the fixing belt 251, that is, the fixing temperature is adjusted to a desired temperature.

  In FIGS. 1 and 2, the fixing device 250 has been described by taking as an example a configuration in which the two rotating bodies of the fixing roller 252 and the fixing heating roller 254 are held within the periphery of the fixing belt 251. It is not limited. For example, the fixing heating roller 254 may be pressed against the pressure roller 256 without the fixing belt 251. When a heater is also included in the pressure roller 256, power supply control according to this embodiment described later can be applied to the heater included in the pressure roller 256. As the heater 253 and the heater 257, a halogen heater can be used, but is not limited thereto.

  The pressure member pressed against the fixing member is not limited to the pressure roller described above that is a pressure rotating body, and may be a belt that is not tensioned or a pressure belt that is wound around a plurality of rollers. It may be a pressure pad that does not rotate or run.

  In FIG. 2, an example in which one thermistor 254C is provided has been described. However, the present invention is not limited to this, and the position and number of thermistors can be changed as appropriate.

  FIG. 3 shows a schematic functional configuration example of the image forming apparatus 100 according to the present embodiment. FIG. 4 is a diagram for explaining an example of a fixing heater driving circuit of the fixing device 250 according to the present embodiment. As shown in FIG. 3, the image forming apparatus 100 according to the present embodiment includes a heat generating unit 253 that is a heater, a step-down unit 105, a control unit 6, a voltage detection unit 107, a heater driving unit 108, and an abnormality detection unit 109. ing.

  The heat generating part is, for example, a heater 253 and heats the fixing heating roller 254. The step-down unit 105 steps down and supplies the voltage supplied from the commercial power source to the heater 253 via the step-down circuit 5. The control unit 6 transmits and receives, for example, a zero cross signal, a thermistor signal, a heater control signal, and the like to control each unit. More specifically, the control unit 6 controls the duty between the energization time and the non-energization time of the heater 253 based on the zero cross point detected by the zero cross signal detection circuit 2. In addition, a heater control signal is generated based on the thermistor signal output from the thermistor 254C, and power supply to the heater 253 is controlled.

  The voltage detection unit 107 detects the voltage supplied to the heater 253 by the heater voltage detection circuit 7. The heater driving unit 108 controls the heater control signal via the heater driving circuit 8. The abnormality detection unit 109 uses the abnormality detection circuit 9 to detect an abnormality in the heater drive circuit 8 from the voltage supplied to the heater 253 and the heater control signal.

  Also, as shown in FIG. 4, the AC input 11 is connected to the noise filter 1 that removes noise from the AC line, and then input to the noise filter 4 via the zero cross signal detection circuit 2 and DB3. Is done. The zero-cross signal detection circuit 2 is a circuit that outputs the Lo voltage to the control unit 6 when the commercial power supply voltage becomes around 0V. The AC input voltage is full-wave rectified by DB3.

  The power supply voltage rectified by DB3 is input to the step-down circuit 5 including, for example, L2, C2, D1, and Q1 through the LC noise filter 4 including L1 and C1, for example. The voltage input to the step-down circuit 5 is switched by Q1, converted into a voltage corresponding to the heater control signal, and input to the heater 253. The heater control signal of the control unit 6 is controlled via the heater drive circuit 8. As the heater 253, a heat source such as a halogen heater or a carbon heater can be applied. The temperature of the heater 253 is detected by the thermistor 254C. The thermistor signal output from the thermistor 254C is input to the control unit 6 and converted to temperature. Based on the temperature state of the heater 253 detected in this way, the control unit 6 determines the power supplied to the heater 253 and outputs a heater control signal.

  The heater control signal is a PWM signal of 20 KHz or more, and the PWM duty can be varied from 0% to 100%. By controlling the PWM duty, the voltage input to the heater 253 can be controlled, and the power supplied to the heater 253 can be controlled. The reason why the PWM signal is 20 kHz or higher is to prevent the generation of abnormal noise. The coil may vibrate when energized according to the frequency, and the vibration may cause abnormal noise. Therefore, the PWM signal is set to a frequency higher than the human audible range.

  In addition, by providing the LC noise filter 4 that is a noise removing unit including L1 and C1, it is possible to prevent noise having a high pulse current frequency due to PWM driving of the heater 253 from leaking to the power supply side.

  The heater voltage detection circuit 7 detects the voltage applied to the heater 253. In the present embodiment, as shown in FIG. 5, the detection voltage output varies according to the voltage applied to the heater 253. The output voltage is converted into a DC voltage by a low-pass filter. In addition, the heater drive circuit 8 converts the signal into a voltage obtained by smoothing the heater control signal as shown in FIG.

  The abnormality detection circuit 9 compares the heater applied voltage supplied to the heater 253 with the heater control signal, and determines whether the heater applied voltage is abnormal with respect to the heater control signal signal. Specifically, the detected value of the heater applied voltage and the output value of the heater control signal are input to COMP1.

  In the present embodiment, when the operation is normal, the detection value of the heater applied voltage is set to be larger than the output value of the heater control signal regardless of whether or not power is supplied to the heater 253. . When the heater applied voltage corresponding to the heater control signal cannot be detected, COMP1 outputs the Lo voltage and inputs it to COMP2. When the output of COMP1 is Lo voltage for a certain period of time compared to the reference voltage, it is determined that the state is abnormal, COMP2 becomes Lo output, SW10 is opened, and power supply to the heater 253 is cut off. .

  Here, when a halogen heater or the like is applied as the heater 253, a so-called inrush current may occur when the halogen heater or the like is cooled. Therefore, the voltage output from the heater voltage detection circuit 7 with respect to the heater control signal is a smaller value than when the steady-state current of the heater 253 is flowing. Therefore, the output of COMP1 is input to COMP2 via an RC filter and compared with a reference voltage, so that malfunction due to the inrush current of the heater 253 can be prevented.

  FIG. 7 shows a flow of a heater power supply control operation example of the fixing device according to the present embodiment. As described above, the heater voltage detection unit 107 first detects a heater applied voltage that is a voltage applied to the heater 253 (step S701). Next, the heater driving signal output by the control unit 6 is detected by the heater driving unit 108 (step S702). Then, the abnormality detection unit 109 compares the heater applied voltage with the heater control signal (step S703), and determines whether or not the power supply state to the heater 253 is abnormal (step S704). In addition, the process of the said step S701 and step S702 may be performed from any and the order is not specifically limited.

  When the voltage based on the heater control signal is not applied to the heater 253 and it is determined that the power supply state to the heater 253 is abnormal (step S704 / YES), the switch 253 is turned off to turn off the heater 253. The power supply to is stopped (step S705). On the other hand, when it is determined that the power supply state to the heater 253 is normal (step S704 / NO), the process proceeds to step S701, and the above-described process is repeated until an abnormal state is detected.

  According to the present embodiment, it is possible to accurately detect an abnormality in the heater applied voltage. As a result, since the power supply can be cut off before the heater temperature becomes abnormally high, the deterioration of the mold member or the pressure roller that is in contact with the fixing heating roller heated by the heater is prevented. Is possible.

(Embodiment 2)
FIG. 8 shows a schematic functional configuration example of the image forming apparatus 100 according to the present embodiment. FIG. 9 is a diagram for explaining an example of a fixing heater driving circuit of the fixing device 250 according to the present embodiment. As shown in FIGS. 8 and 9, the present embodiment is different from the first embodiment in that it includes a cooling processing unit 112 and a heater abnormality signal is input to the control unit 6. In addition, the same code | symbol is attached | subjected to the same structure and the overlapping description is abbreviate | omitted.

  As described in the first embodiment, when the abnormality detection unit 109 detects an abnormality in the power supply state to the heater 253, a heater abnormality signal is input to the control unit 6 in this embodiment. The heater abnormality signal can be output from, for example, the abnormality detection circuit 11, but is not limited thereto.

  FIG. 10 shows a flow of an example of heater power supply control operation of the fixing device according to this embodiment. As described in the first embodiment, first, the heater voltage detection unit 107 detects a heater applied voltage that is a voltage applied to the heater 253 (step S1001). Next, the heater drive signal output by the control unit 6 is detected by the heater drive unit 108 (step S1002). Then, the abnormality detection unit 109 compares the heater applied voltage with the heater control signal (step S1003), and determines whether the power supply state to the heater 253 is abnormal (step S1004). Note that the processes in step S1001 and step S1002 may be performed from any order, and the order is not particularly limited.

  When it is determined that the voltage based on the heater control signal is not applied to the heater 253 and the power supply state to the heater 253 is abnormal (step S1004 / YES), the switch 10 is turned off to turn off the heater 253. Power supply to is stopped (step S1005). In parallel with the processing in step S1005, a heater abnormality signal is input to the control unit 6. Then, the control unit 6 to which the heater abnormality signal has been input causes the cooling processing unit 112 to perform an operation of cooling the fixing heating roller 254 including the heater 253 (step S1006). On the other hand, when it is determined that the power supply state to the heater 253 is normal (step S1004 / NO), the process proceeds to step S1001 and the above-described process is repeated until an abnormal state is detected. Note that the processes in step S1005 and step S1006 may be performed from any order, and the order is not particularly limited.

  Here, as the cooling processing unit 112 for cooling the fixing heating roller 254 including the heater 253, for example, a fixing heating roller driving unit, a fixing heating roller separation unit, a fixing heating roller cooling unit, or the like, which is a cooling processing unit, is applied. can do. The cooling processing means is an example, but the roller containing the heater can be cooled by combining any one or more of these means. In the present embodiment, the fixing heating roller 254 including the heater 253 is described as an example of the roller that the cooling processing unit 112 cools, but is not limited thereto. The cooling processing unit 112 can perform the cooling process as long as it is a rotating body including a heater, and the cooling processing unit 112 may be one or more. Moreover, the object to be cooled is not limited to the rotating body.

  For example, when the fixing heating roller driving unit is applied as the cooling processing unit, when the abnormality detection unit 109 detects an abnormality in the power supply state to the heater 253, a heater abnormality signal is input to the control unit 6. The controller 6 to which the abnormal signal is input starts rotation of the fixing heating roller 254 including the heater 253 by the fixing heating roller driving unit. By rotating the fixing heating roller 254, heat conduction can be performed by a pressure roller, a fixing belt, or the like that is in contact with the fixing heating roller 254, thereby improving heat radiation efficiency. Thereby, since it is possible to prevent the fixing heating roller 254 from becoming an abnormal temperature, it is possible to prevent deterioration of a mold member or the like that is in contact with the fixing heating roller 254.

  Similarly, for example, when a fixing heating roller separation unit is applied as the cooling processing unit, when the abnormality detection unit 109 detects an abnormality in the power supply state to the heater 253, a heater abnormality signal is input to the control unit 6. The controller 6 to which the abnormal signal is input separates the member such as the mold member or the pressure roller that is in contact with the fixing heating roller 254 from the fixing heating roller 254 by the fixing heating roller separation unit, thereby fixing the fixing heating roller 254. It is possible to prevent deterioration of the mold member and the like that are in contact with each other.

  Similarly, for example, when the fixing heating roller cooling unit is applied as the cooling processing unit, when the abnormality detection unit 109 detects an abnormality in the state of power supply to the heater 253, a heater abnormality signal is input to the control unit 6. The controller 6 to which the abnormal signal is input operates a cooling fan installed for cooling the fixing heating roller 254 by the fixing heating roller cooling unit, and prevents the fixing heating roller 254 from becoming an abnormal temperature. As a result, it is possible to prevent deterioration of the mold member or the like that is in contact with the fixing heating roller 254.

  According to the present embodiment, not only the heater power supply state abnormality is detected and the power supply to the heater is interrupted, but also a means for cooling the rotating body or the like including the heater is provided, so that the deterioration of the mold member or the like can be efficiently performed. It becomes possible to suppress.

  Note that a program for the CPU to execute the processing shown in the flowcharts of the respective drawings constitutes a program according to the present invention. As a computer-readable recording medium for recording the program, a semiconductor storage unit, an optical and / or magnetic storage unit, or the like can be used. By using such a program and recording medium in a system having a different configuration from the above-described embodiments and causing the CPU of the system to execute the program, substantially the same effect as the present invention can be obtained. .

  Although specifically described based on the preferred embodiments, the present invention is not limited to the above-described fixing device, image forming apparatus, fixing heater control method, program, and recording medium, and does not depart from the gist thereof. Needless to say, various changes can be made.

DESCRIPTION OF SYMBOLS 1 Noise filter 2 Zero cross signal detection circuit 3 DB
DESCRIPTION OF SYMBOLS 4 Noise filter 5 Voltage drop circuit 6 Control part 7 Heater voltage detection circuit 8 Heater drive circuit 9 Abnormality detection circuit 10 Switch 11 Commercial power supply 100 Image forming apparatus 105 Voltage reduction part 107 Voltage detection part 108 Heater drive part 109 Abnormality detection part 112 Cooling process part 250 Fixing Device 251 Fixing Belt 253 Heater 254 Fixing Heating Roller 254C Thermistor 256 Pressure Roller

JP 2004-191523 A JP 2005-032558 A JP 2009-033905 A

Claims (17)

A step-down means for stepping down the voltage applied to the fixing heater;
Voltage detection means for detecting a heater application voltage that is a voltage applied to the fixing heater;
An abnormality detection that compares a heater control signal for controlling a voltage applied to the fixing heater with a heater application voltage detected by the voltage detection means to determine whether or not the application state to the fixing heater is abnormal. Means,
A fixing device comprising: a blocking unit configured to block application to the fixing heater when the abnormality detection unit determines that the application state to the fixing heater is abnormal.   The fixing device according to claim 1, further comprising a noise removing unit that removes noise.   2. The apparatus according to claim 1, further comprising at least one cooling processing unit configured to cool a rotating body including the fixing heater when the abnormality detection unit determines that the application state to the fixing heater is abnormal. Or the fixing device according to 2;   The fixing device according to claim 3, wherein the cooling processing unit is a cooling fan.   The fixing device according to claim 3, wherein the cooling processing unit is a rotating body driving unit that drives a rotating body including the fixing heater.   6. The cooling unit according to claim 3, wherein when the fixing heater is included, the cooling processing unit is a rotating unit separating unit that separates the rotating body from another member that contacts the rotating body including the fixing heater. The fixing device according to claim 1. Control means for outputting a heater control signal for controlling a voltage applied to the fixing heater;
A step-down means for stepping down a voltage applied to the fixing heater;
Voltage detection means for detecting a heater application voltage that is a voltage applied to the fixing heater;
An abnormality detection unit that compares the heater control signal output by the control unit with the heater application voltage detected by the voltage detection unit, and determines whether the application state to the fixing heater is abnormal;
An image forming apparatus comprising: a blocking unit configured to block application to the fixing heater when the abnormality detection unit determines that the application state to the fixing heater is abnormal.   8. The image forming apparatus according to claim 7, further comprising noise removing means for removing noise. Comprising at least one cooling processing means for cooling the rotating body containing the fixing heater;
The control unit causes the cooling processing unit to cool the rotating body including the fixing heater when the abnormality detecting unit determines that the application state to the fixing heater is abnormal. The image forming apparatus according to claim 7 or 8.   The cooling processing means includes a cooling fan, a rotating body driving means for driving a rotating body including the fixing heater, and another member that contacts the rotating body and the rotating body including the fixing heater when the fixing heater is included. The image forming apparatus according to claim 9, wherein the image forming apparatus includes at least one of a rotating body separating unit and a rotating body separating unit. A step-down step for stepping down the voltage applied to the fixing heater;
A voltage detection step of detecting a heater application voltage that is a voltage applied to the fixing heater;
An abnormality detection that compares a heater control signal for controlling a voltage applied to the fixing heater and a heater application voltage detected in the voltage detection step to determine whether or not an application state to the fixing heater is abnormal. Steps,
A fixing heater control method comprising: a blocking step of cutting off the application to the fixing heater when it is determined in the abnormality detecting step that the application state to the fixing heater is abnormal.   The fixing heater control method according to claim 11, further comprising a noise removing step for removing noise.   The cooling process step of cooling the rotating body containing the fixing heater when the application state to the fixing heater is determined to be abnormal in the abnormality detection step. The fixing heater control method described in 1. A process of stepping down the voltage applied to the fixing heater;
A process of detecting a heater applied voltage that is a voltage applied to the fixing heater;
A process of comparing a heater control signal for controlling a voltage applied to the fixing heater and the heater applied voltage to determine whether or not an application state to the fixing heater is abnormal;
A program for causing a computer to execute a process of cutting off the application to the fixing heater when it is determined that the application state to the fixing heater is abnormal.   15. The program according to claim 14, further causing the computer to execute processing for removing noise.   16. The program according to claim 14 or 15, further causing a computer to execute a process of cooling a rotating body including the fixing heater when it is determined that an application state to the fixing heater is abnormal. .   The computer-readable recording medium which recorded the program of any one of Claim 14 to 16.

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