JP2008170657A - Fixing controller and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately decide abnormality of a triac. <P>SOLUTION: A power supply unit 4 includes: 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 fixing temperature control part 111 for outputting an instruction signal to the triac 41 so as to control the temperature of a fixing roller 532; and a calculation circuit 43 for deciding whether or not the control by the triac 41 is abnormal on the basis of the zero-cross signal and the instruction signal. <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 capable of accurately determining a triac abnormality.

  In order to achieve the above object, a fixing control device according to claim 1 intermittently supplies power from a commercial power source to a fixing heater via a TRIAC (TRIAC: TRIAC: TRIAC) to control the temperature of the fixing roller. A fixing control device for generating a zero-cross signal that is a pulse signal having a predetermined width at a zero-cross point of an alternating voltage applied to the triac from a commercial power supply; Triac control means for outputting an instruction signal to control the temperature of the fixing roller, and determination means for determining whether or not the control of the triac is abnormal based on the zero cross signal and the instruction signal. It is said.

  A fixing control device according to a second aspect is the fixing control device according to the first aspect, wherein the electric power supplied to the fixing heater from the triac is interposed between the triac and the fixing heater. It is characterized by comprising: a shut-off means for shutting off; and a shut-off instruction means for shutting off the electric power via the shut-off means when the determination means judges that the control of the triac is abnormal.

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

  A fixing control device according to a fourth aspect is the fixing control device according to any one of the first to third aspects, wherein the determination unit determines that the control of the triac is abnormal. It is characterized by comprising display control means for outputting information indicating that the control of the triac is abnormal so as to be visible from the outside.

  A fixing control device according to a fifth aspect is the fixing control device according to any one of the first to fourth aspects, wherein the triac is controlled by the abnormality information storage means for storing abnormality information and the determination means. And an abnormality processing means for storing in the abnormality information storage means information indicating that the control of the triac is abnormal.

  A fixing control device according to a sixth aspect of the present invention is the fixing control device according to any one of the first to fifth aspects, wherein the determination unit sends the triac control unit to the fixing heater with respect to the triac. When the instruction signal for stopping the supply of power is output and the zero cross signal is output, it is determined that the control of the triac is abnormal.

  A fixing control device according to a seventh aspect is the fixing control device according to the sixth aspect, wherein the triac control means is an instruction signal for causing the triac to supply power to the fixing heater. The temperature of the fixing roller is controlled by ON / OFF control of a control signal, and the determination means is a NOT circuit to which the triac control signal is input, and an AND circuit to which the output signal of the NOT circuit and the zero cross signal are input The shutoff instruction means shuts off power when the output signal from the AND circuit is in an ON state.

  An image forming apparatus according to an eighth 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. 7. The fixing control device according to claim 7, wherein the fixing control device intermittently supplies power from a commercial power source to a fixing heater provided in the fixing unit, and is provided in the fixing unit. The temperature of the fixing roller is controlled.

  According to the fixing control device of the first aspect, a zero-cross signal that is a pulse signal having a predetermined width set in advance is generated at the zero-cross point of the AC voltage applied to the triac from the commercial power source. An instruction signal is output to control the temperature of the fixing roller. Since it is determined whether or not the triac control is abnormal based on the zero cross signal and the instruction signal, the triac abnormality can be accurately determined.

  That is, the control of the triac is abnormal based on the zero cross signal indicating whether or not power is supplied to the triac from the commercial power supply and the instruction signal output to the triac to control the temperature of the fixing roller. Therefore, it is possible to accurately determine the triac abnormality.

  For example, if an instruction signal to stop power supply to the fixing heater is output to the triac and a zero cross signal indicating that power is being supplied from the commercial power supply to the triac is output, the triac Therefore, it can be determined that the control is abnormal.

  According to the fixing control device of the second aspect, when it is determined that the triac control is abnormal, the electric power supplied from the triac to the fixing heater is cut off, so that the abnormal heating of the fixing heater is prevented. be able to.

  According to the fixing control device of the third 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 fourth aspect, when it is determined that the control of the triac is abnormal, information indicating that the control of the triac is abnormal is output so as to be visible from the outside. Since the user can visually recognize that the control is abnormal, the convenience for the user can be improved.

  According to the fixing control device of the fifth aspect, when it is determined that the triac control is abnormal, the information indicating that the triac control is abnormal is stored in the abnormality information storage unit. By reading the information indicating that the TRIAC control is abnormal stored in the abnormality information storage means, etc., it is possible to confirm that the TRIAC control abnormality has occurred, thereby improving the convenience of maintenance. Can do.

  According to the fixing control device of the sixth aspect, the control of the triac is abnormal when the instruction signal for stopping the supply of power to the fixing heater is output and the zero cross signal is output. Therefore, the triac abnormality can be more accurately determined.

  That is, when the instruction signal for stopping the supply of power to the fixing heater is output and the zero cross signal is output, the TRIAC operates against the instruction signal. It can be determined that it is abnormal.

  According to the fixing control device of the seventh aspect, the temperature of the fixing roller is controlled by performing on / off control of the triac control signal that is an instruction signal for supplying power to the fixing heater with respect to the triac. Further, the triac control signal is input to the NOT circuit, and the output signal of the NOT circuit and the zero cross signal are input to the AND circuit. Since the power is cut off when the output signal from the AND circuit is in the ON state, abnormal heating of the fixing heater can be reliably prevented with a simple configuration.

  That is, the triac control signal, which is an instruction signal for supplying power to the fixing heater with respect to the triac, is in the OFF state (= the output signal from the NOT circuit is in the ON state), and the zero cross signal is in the ON state. In this case, since the output signal from the AND circuit is turned on, it is possible to accurately determine whether or not the triac control is abnormal with a simple configuration.

  According to the image forming apparatus of the eighth aspect, the fixing control device according to any one of the first to seventh aspects intermittently supplies power from the commercial power source to the fixing heater disposed in the fixing unit. The temperature of the fixing roller disposed in the fixing unit is controlled, and an instruction signal is output to control the temperature of the fixing roller with respect to the triac disposed in the fixing control device. It is possible to realize an image forming apparatus capable of accurately determining the image quality.

  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 (corresponding to a part of the display control means) includes an LCD, an LED (Light Emitting Diode), etc., and displays setting information, guidance information, message information, etc. based on an instruction from the control unit 1 (CPU 11). It is displayed so as to be visible to the user. Here, the display unit 3 outputs information indicating that the control of the triac is abnormal to the LCD when the CPU 11 (abnormal control unit 112 described later) determines that the control of the triac is abnormal. .

  The power supply unit 4 (corresponding to a part of 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, This is supplied to the control unit 1, the operation unit 2, the display unit 3, the print processing unit 5, and the like, and includes a triac 41. 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 heated to a predetermined temperature (for example, 180 ° C.) by the fixing heater 531 and sandwiches and conveys the recording paper discharged from the photosensitive unit 52. 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 power supply unit 4 (corresponding to a part of the fixing control device) includes a triac 41, a signal generation circuit 42, an arithmetic circuit 43, and a relay 44. As shown in the figure, the triac 41 and the relay 44 are connected in series with a commercial power source together with the fixing heater 531.

  The CPU 11 (corresponding to a part of the fixing control device) functionally includes a fixing temperature control unit 111 and an abnormality control unit 112, and the RAM 12 (corresponding to a part of the fixing control device) functions. In addition, an abnormality information storage unit 121 is provided. Here, the CPU 11 functions as functional units such as the fixing temperature control unit 111 and the abnormality control unit 112 by reading out and executing a program stored in advance in a ROM (not shown) or the like, and stores the RAM 12 in the abnormality information storage. It functions as a functional unit such as the unit 121.

  Here, among various data stored in the RAM 12 or a ROM (not shown), data that can be stored in a removable recording medium is, for example, a hard disk drive, an optical disk drive, a flexible disk drive, a silicon disk drive, a cassette medium reader, etc. In this case, the recording medium is, for example, a hard disk, an optical disk, a flexible disk, a CD (Compact Disk), a DVD (Digital Versatile Disk), 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. Specifically, the triac 41 supplies power to the fixing heater 531 when a triac control signal that is an instruction signal to supply power to the fixing heater 531 is input from the fixing temperature control unit 111 to control the triac. When no signal is input, the power to the fixing heater 531 is cut off. The triac 41 performs heating control using a so-called phase control method, and controls the surface temperature of the fixing roller 532 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. The data is output to the arithmetic circuit 43 (AND circuit 432 described later). 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 arithmetic circuit 43 (corresponding to determination means and shut-off instruction means) includes a NOT circuit 431 and an AND circuit 432, and the triac 41 is based on the zero cross signal from the signal generation circuit 42 and the instruction signal from the fixing temperature control unit 111. Is determined to be abnormal, and when it is determined that the control of the triac 41 is abnormal, the power supplied from the commercial power source to the triac 41 is cut off via the relay 44 (= A circuit composed of a commercial power source, a triac 41, a relay 44, and a fixing heater 531 is opened).

  The NOT circuit 431 receives a triac control signal, which is an instruction signal for supplying power to the fixing heater 531 from the fixing temperature control unit 111 to the triac 41, and outputs a signal obtained by inverting the triac control signal to the AND circuit 432. To do.

  The AND circuit 432 receives the output signal of the NOT circuit 431 and the zero cross signal from the signal generation circuit 42, performs AND processing on both signals, and outputs the generated output signal to the relay 44 and the CPU 11 (abnormality control unit 112). To do. That is, in the AND circuit 432, the output signal of the NOT circuit 431 is in the ON state (= the triac control signal that is an instruction signal for supplying power from the fixing temperature control unit 111 to the fixing heater 531 to the triac 41 is in the OFF state). When the zero cross signal from the signal generation circuit 42 is ON, an output signal indicating that the control of the triac 41 is abnormal is turned ON.

  The relay 44 (corresponding to a blocking means) is interposed between the triac 41 and the fixing heater 531, and the electric power supplied from the triac 41 to the fixing heater 531 according to an instruction from the arithmetic circuit 43 (= AND circuit 432). Is cut off (= the circuit comprising the commercial power supply, the triac 41, the relay 44, and the fixing heater 531 is opened). That is, the relay 44 supplies power supplied from the triac 41 to the fixing heater 531 when the output signal from the AND circuit 432 is in an ON state (= when it is determined that the control of the triac 41 is abnormal). It is a thing to cut off.

  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. Specifically, the fixing temperature control unit 111 controls the temperature of the fixing roller 532 by performing on / off control of a triac control signal that is an instruction signal for supplying power to the fixing heater 531 to the triac 41. is there.

  The abnormality control unit 112 (corresponding to part of the abnormality processing means and the display control means) is when the output signal from the arithmetic circuit 43 (AND circuit 432) is in the ON state (= the control of the triac 41 is abnormal). Information indicating that the TRIAC control is abnormal is displayed on the LCD disposed in the display unit 3 (for example, “Fixing abnormality. Call a service person”). Display guidance information).

  In addition, the abnormality control unit 112 has an abnormality information storage unit 121 when the output signal from the arithmetic circuit 43 (AND circuit 432) is in an ON state (= when it is determined that the control of the triac 41 is abnormal). In addition, information indicating that the triac control is abnormal (for example, an error code indicating that the triac control is abnormal) is stored (= written).

  The abnormality information storage unit 121 (corresponding to the abnormality information storage unit) stores abnormality information, and information indicating that the control of the triac is abnormal by the abnormality control unit 112 (for example, the control of the triac is abnormal). Error code) is written.

  FIG. 3 is a flowchart showing an example of the operation of the fixing control apparatus according to the present invention. First, the AND circuit 432 determines whether or not the triac control signal is in an OFF state (S101). If it is determined that the triac control signal is not in the OFF state (= is in the ON state) (NO in S101), the process is in a standby state. If it is determined that the triac control signal is in the OFF state (YES in S101), the AND circuit 432 determines whether the zero cross signal is in the ON state (S103).

  If it is determined that the zero-cross signal is not in the ON state (= OFF state) (NO in S103), the process returns to step S101, and the processes after step S101 are repeatedly executed. When it is determined that the zero-cross signal is in the ON state (YES in S103), the AND circuit 432 sets an output signal indicating that the control of the triac 41 is abnormal (S105), and the relay 44 The electric power supplied from the triac 41 to the fixing heater 531 is cut off (S107).

  Then, information indicating that the control of the triac is abnormal is displayed on the LCD disposed in the display unit 3 by the abnormality control unit 112 (S109). Next, information indicating that the triac control is abnormal is written in the abnormality information storage unit 121 by the abnormality control unit 112 (S111), and the process is terminated.

  In this way, a zero-cross signal that is a pulse signal having a predetermined width (here, 2 msec) is generated at the zero-cross point of the AC voltage applied to the triac 41 from the commercial power supply. Then, an instruction signal is output to control the temperature of the fixing roller 532. Since it is determined whether or not the control of the triac 41 is abnormal based on the zero cross signal and the instruction signal, the abnormality of the triac 41 can be accurately determined.

  That is, the control of the triac 41 is based on a zero cross signal indicating whether or not electric power is supplied to the triac 41 from the commercial power source and an instruction signal output to the triac 41 to control the temperature of the fixing roller 532. Therefore, it is possible to accurately determine whether the triac 41 is abnormal.

  For example, when an instruction signal for stopping the supply of power to the fixing heater 531 is output to the triac 41 and a zero cross signal indicating that power is being supplied from the commercial power supply to the triac 41 is output. It can be determined that the control of the triac 41 is abnormal.

  In addition, when it is determined that the control of the triac 41 is abnormal, the power supplied from the triac 41 to the fixing heater 531 is cut off, so that abnormal heating of the fixing heater 531 can be prevented.

  Furthermore, since power is cut off via the relay 44, abnormal heating of the fixing heater 531 can be reliably prevented with a simple configuration.

  In addition, when it is determined that the control of the triac 41 is abnormal, information indicating that the control of the triac is abnormal is displayed on the LCD provided in the display unit 3, so that the control of the triac 41 is abnormal. Therefore, the user's convenience can be improved.

  Further, when it is determined that the control of the triac 41 is abnormal, information indicating that the control of the triac 41 is abnormal is stored in the abnormality information storage unit 121, so that a serviceman or the like is stored in the abnormality information storage unit 121. By reading out information indicating that the stored control of the triac 41 is abnormal, it is possible to confirm that an abnormality in the control of the triac 41 has occurred, so that the convenience of maintenance can be improved.

  Further, when an instruction signal for stopping the supply of power to the fixing heater 531 is output and a zero cross signal is output, it is determined that the control of the triac 41 is abnormal. Abnormalities can be determined more accurately.

  That is, when an instruction signal for stopping the supply of power to the fixing heater 531 is output and a zero-cross signal is output, the triac 41 operates against the instruction signal. Therefore, it can be determined that the control is abnormal.

  In addition, the temperature of the fixing roller 532 is controlled by on / off controlling a triac control signal that is an instruction signal for supplying power to the fixing heater 531 with respect to the triac 41. Further, the triac control signal is input to the NOT circuit 431, and the output signal of the NOT circuit 431 and the zero cross signal are input to the AND circuit 432. Then, when the output signal from the AND circuit 431 is in the ON state, the power is cut off, so that abnormal heating of the fixing heater 531 can be reliably prevented with a simple configuration.

  That is, the triac control signal, which is an instruction signal for supplying power to the fixing heater 531 to the triac 41, is in the OFF state (= the output signal from the NOT circuit 431 is ON), and the zero cross signal is ON. In this state, since the output signal from the AND circuit 431 is turned on, it is possible to accurately determine whether or not the control of the triac 41 is abnormal with a simple configuration.

The present invention can also be applied to the following forms.
(A) In the present embodiment, the case where the interruption means includes the relay 44 has been described. However, the power may be interrupted by another circuit. For example, the cut-off means may cut off power through a transistor switch.

  (B) In the present embodiment, the case where the determination unit includes the NOT circuit 431 and the AND circuit 432 has been described. However, the determination unit may include another circuit, or may be configured as a functional unit in the CPU 11. Good. For example, the CPU 11 may include a functional unit that determines whether the control of the triac 41 is abnormal based on the triac control signal from the fixing temperature control unit 111 and the zero cross signal from the signal generation circuit 42.

FIG. 2 is a block diagram illustrating an example of a schematic configuration of a printer according to the present invention. FIG. 2 is a configuration diagram showing an example of a configuration of a fixing control device according to the present invention. These are flowcharts showing an example of the operation of the fixing control device.

Explanation of symbols

100 Printer 1 Control unit 11 CPU (part of fixing control device)
111 Fixing temperature control unit (part of triac control means)
112 Abnormal control unit (abnormal processing means, part of display control means)
12 RAM (part of fixing control device)
121 Abnormal information storage unit (abnormal information storage means)
3 Display (part of display control means)
4 Power supply unit (part of fixing control device)
41 triac 42 signal generation circuit (signal generation means)
43 arithmetic circuit (determination means, shut-off instruction means)
431 NOT circuit 432 AND circuit 44 Relay (blocking means)
5 Print Processing Unit 53 Fixing Unit 531 Fixing Heater 532 Fixing Roller 533 Temperature Sensor (Part of Triac Control Unit)

Claims (8)

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,
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;
A triac control means for outputting an instruction signal to control the temperature of the fixing roller with respect to the triac;
Determination means for determining whether the control of the triac is abnormal based on the zero-cross signal and the instruction signal;
A fixing control device comprising: A blocking means interposed between the triac and the fixing heater, for cutting off power supplied from the triac to the fixing heater;
When the determination unit determines that the control of the triac is abnormal, a cutoff instruction unit that cuts off power through the cutoff unit;
The fixing control device according to claim 1, further comprising:   The fixing control device according to claim 2, wherein the shut-off unit includes a relay and cuts off electric power through the relay.   The display control means for outputting information indicating that the control of the triac is abnormal so as to be visible from the outside when the determination means determines that the control of the triac is abnormal. The fixing control device according to claim 1. Abnormality information storage means for storing abnormality information;
An abnormality processing means for storing in the abnormality information storage means information indicating that the control of the triac is abnormal when the determination means determines that the control of the triac is abnormal;
The fixing control device according to claim 1, further comprising:   The determination means outputs an instruction signal for stopping the supply of electric power to the fixing heater from the triac control means to the triac, and when the zero cross signal is output. The fixing control apparatus according to claim 1, wherein the control is determined to be abnormal. The triac control means controls the temperature of the fixing roller by controlling on / off a triac control signal that is an instruction signal for supplying power to the fixing heater with respect to the triac,
The determination means includes
A NOT circuit to which the triac control signal is input;
An AND circuit to which the output signal of the NOT circuit and the zero cross signal are input;
With
The fixing control device according to claim 6, wherein the cutoff instruction unit cuts off the power when an output signal from the AND circuit is in an ON state. 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 7,
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.

Images