JP2008170656A - Fixing controller and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely prevent abnormal heating of a fixing heater. <P>SOLUTION: A power supply unit 4 includes: a relay 47 interposed between a triac 41 and the fixing heater 531, for shutting off power supplied from the triac 41 to the fixing heater 531; a signal generation circuit 42 for generating a zero-cross signal as a pulse signal having a previously set specified width at the zero-cross point of AC voltage applied from a commercial power supply to the triac 41; a counter 43 for counting the number of generated zero-cross signals; a reset circuit 44 for outputting a reset signal to the counter 43 when the zero-cross signal is not input for a prescribed period or longer; and a calculation circuit 46 for deciding whether or not the counted value counted by the counter 43 is equal to a previously set threshold or greater, and for shutting off the power via the relay 47 when it is decided that the value is equal to the threshold or greater. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fixing control apparatus and an image forming apparatus that control the temperature of a fixing roller by intermittently supplying power from a commercial power source to a fixing heater via a TRIAC (TRIAC). In particular, the present invention relates to a copying machine, a facsimile machine, an Internet facsimile machine, a network printer, and a multifunction machine having at least one of these functions.

  2. Description of the Related Art Conventionally, in a fixing control device that is disposed in an image forming apparatus such as a copying machine and controls the temperature of a fixing roller, a CPU (Central Processing Unit) is based on a temperature signal input from a thermistor that detects the temperature of the fixing roller. The power supply to the fixing heater is supplied to and stopped from the triac. However, the fixing roller may become abnormally hot due to software runaway in the CPU, thermistor failure, triac failure, and the like, which may cause damage to the fixing roller.

Various apparatuses and methods have been proposed for the above problems. For example, it is only when it is confirmed that the software that is operating normally is determined by monitoring whether the temperature of the fixing heater is regularly monitored and detecting whether there is an abnormality. A fixing device that cancels forced OFF of a heater relay that controls ON / OFF of a fixing heater (= which enables heating by a fixing heater) is disclosed (see Patent Document 1). According to this fixing device, abnormal heating of the fixing heater can be prevented even when software runaway occurs.
JP 2005-91935 A

  However, even in the fixing device, the fixing roller may become abnormally hot due to a failure of the triac or the like, and the fixing roller may be damaged. For example, if the software is operating normally, the forced relay of the heater relay that controls the on / off of the fixing heater will be released (= heating by the fixing heater will be possible), so if the TRIAC fails in a shorted state In this case, the fixing roller may be heated to an abnormally high temperature by being continuously heated by the fixing heater.

  SUMMARY An advantage of some aspects of the invention is that it provides a fixing control device and an image forming apparatus that can reliably prevent abnormal heating of a fixing heater.

  In order to achieve the above object, a fixing control device according to claim 1 is a fixing control device that intermittently supplies power from a commercial power source to a fixing heater via a triac to control the temperature of a fixing roller. Preliminarily set at a zero-crossing point of an AC voltage applied from the commercial power source to the triac, and a cutoff means interposed between the triac and the fixing heater, which cuts off the electric power supplied from the triac to the fixing heater. A signal generating unit that generates a zero-cross signal that is a pulse signal having a predetermined width, a counting unit that counts the number of zero-cross signals generated by the signal generating unit, and a zero-cross signal generated by the signal generating unit in advance. A reset signal is output to the counting means when there is no input for a predetermined period. It is determined whether the count value counted by the reset means and the counting means is greater than or equal to a preset threshold value. If it is determined that the count value is greater than or equal to the threshold value, the power is shut off via the shut-off means. And a judging means for making it.

  A fixing control device according to a second aspect is the fixing control device according to the first aspect, wherein the shut-off means includes a relay and cuts off the electric power via the relay.

  A fixing control device according to a third aspect is the fixing control device according to the first or second aspect, wherein the reset means outputs a reset signal when a zero-cross signal is not input for approximately 200 msec or more. It is characterized by.

  A fixing control device according to a fourth aspect of the present invention is the fixing control device according to any one of the first to third aspects, further comprising threshold storage means for storing the threshold, and the determination means is the threshold storage. The count value is determined based on the threshold value stored in the means.

  A fixing control device according to a fifth aspect is the fixing control device according to the fourth aspect, wherein the threshold value storage means sets the temperature of the fixing roller to be equal to or lower than a predetermined temperature as the threshold value. The feature is that the value is set.

  A fixing control device according to a sixth aspect is the fixing control device according to the fifth aspect, wherein the fixing roller is made of silicone rubber, and the threshold storage means sets the temperature of the fixing roller as the threshold. The value is set to be approximately 300 ° C. or less which is set in advance.

  An image forming apparatus according to a seventh aspect includes a fixing unit having a fixing roller and a fixing heater for heating the fixing roller, and fixing the transferred toner onto a recording sheet to form an image. 6. A fixing control device according to claim 6, and a triac control means for outputting an instruction signal to control a temperature of the fixing roller with respect to a triac disposed in the fixing control device. The apparatus is characterized in that electric power is intermittently supplied from a commercial power source to a fixing heater provided in the fixing unit to control the temperature of the fixing roller provided in the fixing unit.

  According to the fixing control device according to claim 1, a zero-cross signal that is a pulse signal having a predetermined width set in advance is generated at a zero-cross point of an AC voltage applied to the triac from a commercial power supply, and the generated zero-cross signal is generated. Are counted. In addition, when the generated zero cross signal is not input for a predetermined period or longer, a reset signal for resetting the count value is output. Then, it is determined whether or not the counted value is equal to or greater than a preset threshold value. When it is determined that the counted value is equal to or greater than the threshold value, the power supplied from the triac to the fixing heater is cut off, so that fixing is performed. Abnormal heating of the heater can be reliably prevented.

  In other words, if the triac fails in a shorted state, the power is continuously supplied to the fixing heater, so the count value will not be reset, so the count value is equal to or greater than a preset threshold value. At that time, the power supplied from the triac to the fixing heater is cut off. In a normal state, when the fixing heater reaches a preset temperature, the power supplied from the commercial power source to the fixing heater via the triac is intermittently cut off (= the power is continuously supplied). Therefore, the zero-cross signal is not input for a predetermined period (for example, 200 msec) for a preset period, so that the count value is reset and the count value does not exceed the preset threshold value.

  According to the fixing control device of the second aspect, since the electric power is cut off via the relay, abnormal heating of the fixing heater can be reliably prevented with a simple configuration.

  According to the fixing control device of the third aspect, since the reset signal is output when the zero-cross signal is not input for approximately 200 msec or more, abnormal heating of the fixing heater can be further reliably prevented.

  That is, since the zero cross signal is generated at the zero cross point of the AC voltage applied to the triac from the commercial power supply, it is 8.3 msec (= 1 / (60 × 2) sec) or 10 msec (= 1 / (50 × 2). ) Is generated every sec). In addition, when the fixing heater control is operating normally and the fixing roller reaches a preset temperature (for example, 180 ° C.), the AC voltage applied to the triac is intermittently cut off. Is done. Therefore, since the reset signal is output when the zero-cross signal is not input for approximately 200 msec or longer, the zero-cross point of the AC voltage from the commercial power source can be detected 20 to 30 times during 200 msec. A reset signal is output.

  According to the fixing control device of the fourth aspect, the threshold value of the count value for determining whether or not to cut off the electric power is stored in the threshold value storage unit, and the count is performed based on the threshold value stored in the threshold value storage unit. Since the value is determined, it is possible to appropriately determine whether or not to cut off the power with a simple configuration by storing an appropriate threshold value in the threshold value storage means.

  According to the fixing control device of the fifth aspect, the threshold value storage means sets the threshold value of the count value for determining whether or not to cut off the power so that the temperature of the fixing roller is equal to or lower than a predetermined temperature. Since the value is set, the temperature of the fixing roller can be set to a predetermined temperature (for example, 300 ° C.) or lower, so that abnormal heating of the fixing heater can be prevented more reliably.

  According to the fixing control device of the sixth aspect, the fixing roller is made of silicone rubber, and the temperature of the fixing roller is set in advance as a threshold value of a count value for determining whether or not to cut off the power in the threshold value storage unit. Since the value is set to be approximately 300 ° C. or less, the fixing roller temperature can be approximately 300 ° C. or less, which is the melting temperature of the silicone rubber, so that the fixing roller can be prevented from being damaged. .

  According to the image forming apparatus of the seventh aspect, the fixing control device according to any one of the first to sixth aspects intermittently supplies power from a commercial power source to the fixing heater disposed in the fixing unit. The temperature of the fixing roller provided in the fixing unit is controlled, and an instruction signal is output to control the temperature of the fixing roller to the triac provided in the fixing control device. An image forming apparatus capable of reliably preventing abnormal heating can be realized.

  Hereinafter, an example of an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an example of a schematic configuration of an image forming apparatus according to the present invention. Here, the case where the image forming apparatus is a printer will be described. However, the image forming apparatus may be another image forming apparatus (for example, a facsimile, an internet facsimile, a copying machine, a multifunction machine, etc.) that forms an image on recording paper. Good. As shown in FIG. 1, the printer 100 includes a control unit 1, an operation unit 2, a display unit 3, a power supply unit 4, and a print processing unit 5. The printer 100 is communicably connected to an unillustrated personal computer (PC) or the like, receives an image from the personal computer (PC) or the like, and forms an image corresponding to the received image on a recording sheet.

  The control unit 1 controls the overall operation of the printer 100, and includes a CPU (Central Processing Unit) 11, a RAM (Random Access Memory) 12, and a ROM (Read Only Memory) (not shown).

  The operation unit 2 receives an operation input from a user, generates operation input information corresponding to the received operation input, and outputs the operation input information to the control unit 1 (CPU 11). The operation unit 2 includes, for example, various buttons such as a numeric keypad and a start button, and a touch panel formed integrally with an LCD (Liquid Crystal Display) disposed on the display unit 3.

  The display unit 3 includes an LCD, an LED (Light Emitting Diode), and the like, and displays setting information, guidance information, message information, and the like so as to be visible to the user based on an instruction from the control unit 1 (CPU 11).

  The power supply unit 4 (corresponding to the fixing control device) generates a predetermined DC voltage (for example, 5 V and 24 V) using an AC voltage (for example, 100 V, 60 Hz) supplied from a commercial power source, and the control unit 1 The operation unit 2, the display unit 3, the print processing unit 5, and the like are provided, and a triac 41 is provided. A TRIAC 41 (TRIAC: TRIode AC switch) supplies or cuts power to the fixing heater 531 disposed in the fixing unit 53 of the print processing unit 5 in accordance with an instruction from the CPU 11 (fixing temperature control unit 111 described later). It is.

  The print processing unit 5 forms an image (here, an image corresponding to an image received from a personal computer (PC) or the like) on a recording paper by an electrophotographic method, and includes a developing unit 51, a photosensitive unit 52, In addition, a fixing unit 53 is provided. The developing unit 51 forms a toner image by attaching toner to an electrostatic latent image formed on a photosensitive drum provided in the photosensitive unit 52. The photosensitive unit 52 includes a photosensitive drum. First, the surface of the photosensitive drum is substantially uniformly charged by a charging roller, and then an electrostatic latent image is formed by a laser beam scanning unit (not shown). By 51, a toner is attached to form a toner image, and the toner image formed on the photosensitive drum is transferred to a recording sheet.

  The fixing unit 53 includes a fixing heater 531, a fixing roller 532, and a temperature sensor 533, and conveys the toner image transferred from the photosensitive drum to the recording paper by the photosensitive unit 52 with the fixing roller 532 sandwiching the recording paper. Thus, it is melted and fixed, and fixed on the recording paper.

  The fixing heater 531 heats the fixing roller 532 by Joule heat (or induction heating) such as a halogen lamp. The fixing roller 532 is configured such that its surface is coated with silicone rubber having a melting temperature of about 300 ° C., heated to a predetermined temperature (for example, 180 ° C.) by the fixing heater 531, and discharged from the photosensitive unit 52. The paper is sandwiched and conveyed. The temperature sensor 533 (corresponding to a part of the triac control means) is composed of a thermistor or the like, and measures the surface temperature of the fixing roller 532. A temperature signal corresponding to the measured temperature is sent to the CPU 11 (described later). Is output to the fixing temperature control unit 111).

  FIG. 2 is a block diagram showing an example of the configuration of the fixing control apparatus according to the present invention. The fixing control device (= power supply unit 4) includes a triac 41, a signal generation circuit 42, a counter 43, a reset circuit 44, a threshold memory 45, an arithmetic circuit 46, and a relay 47. As shown in the figure, the triac 41 and the relay 47 are connected in series with a commercial power source together with the fixing heater 531.

  Further, the CPU 11 functionally includes a fixing temperature control unit 111. Here, the CPU 11 functions as a functional unit such as the fixing temperature control unit 111 by reading and executing a program stored in advance in a ROM (not shown) or the like.

  Here, among various data stored in the RAM 12 shown in FIG. 1 or a ROM (not shown), data that can be stored in a removable recording medium includes, for example, a hard disk drive, an optical disk drive, a flexible disk drive, a silicon disk drive, and a cassette. The recording medium may be readable by a driver such as a medium reader. In this case, the recording medium is, for example, a hard disk, an optical disk, a flexible disk, a CD, a DVD, a semiconductor memory, or the like.

  The triac 41 supplies or cuts off power to the fixing heater 531 in accordance with an instruction from the fixing temperature control unit 111. The triac 41 performs heating control using a so-called phase control system, and controls the surface temperature of the fixing roller by controlling the duty ratio of the supplied power.

  The signal generation circuit 42 (corresponding to a signal generation means) generates a zero cross signal that is a pulse signal having a predetermined width (for example, 2 msec) at a zero cross point of an AC voltage applied to the triac 41 from a commercial power source. And output to the counter 43 and the reset circuit 44. The signal generation circuit 42, for example, full-wave rectifies the voltage supplied from the commercial power supply, and zero-crosses the pulse signal that is turned on when the generated pulsating current is equal to or lower than a predetermined threshold voltage set in advance. It is generated as a signal.

  The counter 43 (corresponding to the counting means) counts the number of zero-cross signals input from the signal generation circuit 42. When the reset signal is input from the reset circuit 44, the counter 43 counts the number of zero-cross signals. The count value is reset to zero.

  The reset circuit 44 (corresponding to a reset unit) outputs a reset signal to the counter 43 when a zero-cross signal is not input from the signal generation circuit 42 for a predetermined period (for example, 200 msec). . That is, since the zero cross signal is generated at the zero cross point of the AC voltage applied to the triac from the commercial power supply, it is generated every 8.3 msec (= 1 / (60 × 2) sec). In addition, when the control of the fixing heater 531 is operating normally and the fixing roller 532 reaches a predetermined temperature (for example, 180 ° C.), the AC voltage applied to the triac 41 is intermittent. Is blocked. Therefore, since the reset signal is output when the zero cross signal is not input for 200 msec or longer, the zero cross point of the AC voltage from the commercial power source can be detected 24 (= 200 msec / 8.3 msec) times during 200 msec. is there.

  That is, even when the zero cross signal is not generated from the signal generation circuit 42 due to voltage fluctuations of the commercial power supply or the like, it is possible to prevent the reset signal from being erroneously output from the reset circuit 44 (= It is possible to prevent the timing at which the relay 47 is turned off from being delayed).

  A threshold value memory 45 (corresponding to a threshold value storage means) preliminarily sets a threshold value relating to a count value of a zero cross signal used for determining whether or not to cut off power supplied to the triac 41 via the relay 47 in the arithmetic circuit 46. To store. Here, the threshold value is set so that the temperature of the fixing roller 532 is equal to or lower than a predetermined temperature (300 ° C. in this case) set in advance.

  Specifically, when power is continuously supplied from the triac 41 to the fixing heater 531 for 20 seconds, when the temperature reaches 300 ° C. from normal temperature (= 25 ° C.), for example, zero cross corresponding to 18 seconds. The signal count value is set as a threshold value. Since the zero cross signal is generated every 8.3 msec (= 1 / (60 × 2) sec) by the signal generation circuit 42, 2170 (= 18 sec / (8.3 msec × 0.001)) is set as the threshold value. And stored in the threshold memory 45.

  The arithmetic circuit 46 (corresponding to the determination means) determines whether or not the count value counted by the counter 43 is equal to or greater than a preset threshold value (2170 in this case), and is determined to be equal to or greater than the threshold value. In this case, the power supplied from the commercial power source to the triac 41 is cut off via the relay 47 (= the circuit including the commercial power source, the triac 41, the relay 47, and the fixing heater 531 is opened).

  The relay 47 (corresponding to a cutoff means) is interposed between the triac 41 and the fixing heater 531 according to an instruction from the arithmetic circuit 46, and cuts off the electric power supplied from the triac 41 to the fixing heater 531 (= commercial). A circuit including a power source, a triac 41, a relay 47, and a fixing heater 531 is opened).

  The fixing temperature control unit 111 (corresponding to a part of the triac control unit) instructs the triac 41 to control the temperature of the fixing roller 532 based on a temperature signal indicating the surface temperature of the fixing roller 532 from the temperature sensor 533. To output an instruction signal.

  FIG. 3 is a flowchart showing an example of the operation of the fixing control device (= power supply unit 4). First, the signal generation circuit 42 determines whether or not the triac 41 is in an ON state (= a state in which power is supplied to the fixing heater 531) (S101). If it is determined that the triac 41 is in the ON state (YES in S101), the process proceeds to step S107. If it is determined that the triac 41 is not in the ON state (NO in S101), the reset circuit 44 determines whether or not the zero cross signal has been input for a predetermined period (200 msec in this case) or longer. Is performed (S103). When it is determined that the input has not been input for a predetermined period (here, 200 msec) (YES in S103), the reset circuit 44 outputs a reset signal to the counter 43 (S105), and the process proceeds to step S101. The process after step S101 is repeatedly executed. If it is determined that the period during which no zero cross signal is input has not yet reached the predetermined period (here, 200 msec) (NO in S103), the process returns to step S101, and the processes after step S101 are repeatedly executed. Is done.

  If YES in step S107, a zero cross signal is generated by the signal generation circuit 42 and output to the counter 43 and the reset circuit 44 (S107). Then, the counter 43 increments the count value of the number of zero-cross signals input from the signal generation circuit 42 by 1 (S109). Next, the arithmetic circuit 46 determines whether or not the count value counted by the counter 43 is greater than or equal to a preset threshold value (2170 in this case) (S111). If it is determined that the count value is not equal to or greater than the threshold value (2170 in this case) (= the count value is less than the threshold value) (NO in S111), the process returns to step S101, and the processes after step S101 are performed. It is executed repeatedly. If it is determined that the count value is equal to or greater than the threshold value (2170 in this case) (NO in S111), the arithmetic circuit 46 turns off the relay 47 (= power is cut off) (S113), and the process ends. Is done.

  In this manner, a zero-cross signal that is a pulse signal having a predetermined width (here, 2 msec) set in advance is generated at the zero-cross point of the AC voltage applied to the triac 41 from the commercial power supply. The number is counted. Further, when the generated zero-cross signal is not input for a predetermined period (here, 200 msec) for a predetermined period, a reset signal for resetting the count value is output. Then, it is determined whether or not the counted value is equal to or greater than a preset threshold value (2170 in this case). When it is determined that the counted value is equal to or greater than the threshold value, the triac 41 supplies the fixing heater 531 with the count value. Since the electric power is cut off, abnormal heating of the fixing heater 531 can be reliably prevented.

  In other words, when the triac 41 is in a short-circuited state and fails, power is continuously supplied to the fixing heater 531, and the count value is not reset. Therefore, the count value is set to a preset threshold value (here. In this case, the power supplied from the triac 41 to the fixing heater 531 is cut off when 2170) or more is reached. In a normal state, when the fixing heater 531 reaches a preset temperature (here, 180 ° C.), the power supplied from the commercial power source to the fixing heater 531 via the triac 41 is intermittently cut off ( = No power is continuously supplied), so the zero cross signal is not input for a predetermined period (for example, 200 msec) for a preset time, so the count value is reset and the count value is equal to or greater than a preset threshold value. Never become.

  In addition, since power is cut off via the relay 47, abnormal heating of the fixing heater 531 can be reliably prevented with a simple configuration.

  Further, since the reset signal is output when the zero-cross signal is not input for 200 msec or longer, abnormal heating of the fixing heater 531 can be further reliably prevented.

  That is, since the zero cross signal is generated at the zero cross point of the AC voltage applied to the triac 41 from the commercial power supply, it is generated every 8.3 msec (= 1 / (60 × 2) sec). Further, when the control of the fixing heater 531 is operating normally and the fixing roller 532 reaches a predetermined temperature (180 ° C. in this case), the AC voltage applied to the triac 41 is increased. Interrupted intermittently. Therefore, since the reset signal is output when the zero-cross signal is not input for 200 msec or longer, the zero-cross point of the AC voltage from the commercial power supply can be detected 24 times during 200 msec. It is output.

  In addition, the threshold value of the count value for determining whether to cut off the power is stored in the threshold value memory 45, and the count value is determined based on the threshold value stored in the threshold value memory 45. Is stored in the threshold memory 45, it is possible to appropriately determine whether or not to cut off the power with a simple configuration.

  In addition, since the threshold value memory 45 is set so that the temperature of the fixing roller 532 is equal to or lower than a predetermined temperature set as a threshold value of a count value for determining whether to cut off the power, the fixing roller Since the temperature 532 can be set to a predetermined temperature (300 ° C. or less) set in advance, abnormal heating of the fixing heater 531 can be prevented more reliably.

  Further, the fixing roller 532 is made of silicone rubber, and the threshold memory 45 uses a value to set the temperature of the fixing roller 532 to 300 ° C. or less as a threshold value of a count value for determining whether or not to cut off power. Since the temperature of the fixing roller 532 can be set to 300 ° C. or less, which is the melting temperature of the silicone rubber, the fixing roller 532 can be prevented from being damaged.

The present invention can also be applied to the following forms.
(A) In this embodiment, although the case where the interruption | blocking means was provided with the relay 47 was demonstrated, the form which interrupts | blocks electric power with another circuit may be sufficient. For example, the cut-off means may cut off power through a transistor switch.

  (B) Although the case where the surface of the fixing roller 532 is made of silicone rubber has been described in the present embodiment, the surface of the fixing roller 532 may be made of another material (for example, resin). In this case, it is necessary to set a threshold value stored in the threshold value memory 45 based on the melting temperature of the material constituting the surface of the fixing roller 532.

FIG. 2 is a block diagram illustrating an example of a schematic configuration of a printer according to the present invention. These are the block diagrams which show an example of a structure of the fixing control apparatus (= power supply unit) which concerns on this invention. These are flowcharts showing an example of the operation of the fixing control device (= power supply unit).

Explanation of symbols

100 Printer 1 Control unit 11 CPU
111 Fixing temperature controller (part of fixing temperature control means)
4 power supply unit 41 triac 42 signal generation circuit (signal generation means)
43 Counter (Counting means)
44 Reset circuit (reset means)
45 threshold memory (threshold storage means)
46 arithmetic circuit (determination means)
47 Relay (blocking means)
DESCRIPTION OF SYMBOLS 5 Print processing part 53 Fixing unit 531 Fixing heater 532 Fixing roller 533 Temperature sensor (a part of fixing temperature control means)

Claims (7)

A fixing controller that intermittently supplies power from a commercial power source to a fixing heater via a TRIAC (TRIAC: TRIAC: TRIAC) to control the temperature of a fixing roller,
A blocking means interposed between the triac and the fixing heater, for cutting off power supplied from the triac to the fixing heater;
Signal generating means for generating a zero-cross signal which is a pulse signal having a predetermined width set in advance at a zero-cross point of an alternating voltage applied to the triac from a commercial power supply;
Counting means for counting the number of zero-cross signals generated by the signal generating means;
A reset unit that outputs a reset signal to the counting unit when the zero-cross signal generated by the signal generating unit is not input for a predetermined period or longer; and
A determination unit that determines whether the count value counted by the counting unit is equal to or greater than a preset threshold value, and when it is determined that the count value is equal to or greater than the threshold value, ,
A fixing control device comprising:   The fixing control device according to claim 1, wherein the shut-off unit includes a relay, and cuts off electric power through the relay.   The fixing control apparatus according to claim 1, wherein the reset unit outputs a reset signal when a zero-cross signal is not input for approximately 200 msec or longer. Threshold storage means for storing the threshold value,
The fixing control device according to claim 1, wherein the determination unit determines a count value based on a threshold value stored in the threshold value storage unit.   The fixing control apparatus according to claim 4, wherein the threshold storage unit sets a value as the threshold so that the temperature of the fixing roller is equal to or lower than a predetermined temperature set in advance. The fixing roller is made of silicone rubber,
6. The fixing control apparatus according to claim 5, wherein the threshold value storage unit sets a value as the threshold value so that a temperature of the fixing roller is set to approximately 300 ° C. or less which is set in advance. A fixing unit having a fixing roller and a fixing heater for heating the fixing roller, and fixing the transferred toner on the recording paper to form an image;
A fixing control device according to any one of claims 1 to 6,
A triac control means for outputting an instruction signal to control the temperature of the fixing roller with respect to a triac disposed in the fixing control device;
With
The fixing control device intermittently supplies power from a commercial power source to a fixing heater provided in the fixing unit, and controls the temperature of a fixing roller provided in the fixing unit. apparatus.

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