JP2001125427A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device which can evade a dangerous state due to abnormality when a fixing device possibly has an error in fixation as an image forming device equipped with a fixing device which can fix a toner image carried on a recording medium at fixation temperature raised and set by a heat source. SOLUTION: This device is equipped with a thermistor 25 which detects the temperature of heat sources 21 and 23, a control means which judges whether or not the fixing device 12 has fixation temperature abnormality according to information from the thermistor 25, a nonvolatile storage medium 32 which stores abnormality information, and a warning means which displays a warning when the control means judges the abnormality; when abnormality is judged, the power supply to the heat sources 21 and 23 is cut off first, information on the abnormality occurrence is stored on the nonvolatile storage medium 32, and a warning of the abnormal state is given by the warning means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as a copier, a printer, a facsimile, etc., having a fixing device.

[0002]

2. Description of the Related Art In an image forming apparatus provided with a fixing device for fixing a toner image carried on a recording medium at a fixing temperature set by heating with a heat source, a heat source detecting means or temperature information from the temperature detecting means is used. If the temperature control function for performing the feedback control based on the error occurs, a so-called fixing error occurs.

[0003] The fixing error includes a so-called low-temperature error at start-up, which occurs when a predetermined fixing temperature is not detected after the power is turned on to the electric heater as a heat source, and a fixing roller temperature. There is a thermistor failure error that occurs when it is determined that the device or the thermistor that has failed has failed.

[0004] The above-mentioned low temperature error at startup also occurs when the thermistor fails. This is a case where the duty value of the heater as a heat source is determined by feedback control based on temperature information from the thermistor. It is considered that this occurs when the temperature is higher than the feedback value from the thermistor, and there is a risk of ignition, so urgent action is required.

[0005] The above-mentioned thermistor failure error is considered to be a failure of the thermistor when the feedback value from the thermistor fluctuates during power-on or during normal operation, and causes a fatal failure in the fixing control. Will be.

In any of these cases, if the actual fixing temperature is too high than the predetermined fixing temperature, a fixing failure due to excessive fixing temperature occurs, and the actual fixing temperature is lower than the predetermined fixing temperature. If it is too long, unfixed defects occur.

Japanese Patent Application Laid-Open No. Hei 10-91034 discloses an apparatus in which a medium for storing replacement time of a fixing unit is provided on the apparatus main body side. There is no suggestion.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of avoiding a dangerous state due to an abnormality when the fixing apparatus is in a state where a fixing error can occur. I do.

[0009]

The present invention has the following configuration to achieve the above object. (1). In an image forming apparatus provided with a fixing device for fixing a toner image carried on a recording medium at a fixing temperature set by heating with a heat source, a temperature detecting unit for detecting a temperature by the heat source, and a temperature from the temperature detecting unit. A control unit that determines whether there is an abnormality in the fixing temperature in the fixing device based on the information, and a nonvolatile unit that is provided in the fixing device and stores the abnormality information when the control unit determines that the abnormality is present. Storage medium, and a warning unit that displays a warning when the control unit determines that the abnormality is present. When the control unit determines that the abnormality is present, first, The energy supply is cut off, and then information on the presence of an abnormality is stored in the non-volatile storage medium, and a warning of an abnormal situation is issued by the warning means. 1). (2). (1) The image forming apparatus according to (1), wherein a low-speed mode in which the feeding speed of the recording medium in the fixing device is low, and a low-speed mode of the recording medium in the fixing device according to a resolution of an image formed by the image forming device. When the speed can be switched to any one of the high-speed mode and the high-speed mode, control is performed so as to lower the temperature of the heat source in the low-speed mode and increase the temperature of the heat source in the high-speed mode. ). (3). In the image forming apparatus according to (1) or (2), when the low speed mode is switched to the high speed mode, a low fixing temperature set for the low speed mode is set to a high fixing temperature set for the high speed mode. The energy supply level to the heat source is switched so as to satisfy the following condition, and the feeding of the recording medium is not started until the fixing temperature rises to a predetermined fixing temperature suitable for the high-speed mode. (4). (2) In the image forming apparatus described in (2), when the high-speed mode is switched to the low-speed mode, the high fixing temperature set for the high-speed mode is changed to a low fixing temperature set for the low-speed mode. The supply of the recording medium is not started until the energy supply level to the heat source is switched and the fixing temperature drops to a predetermined fixing temperature suitable for the low-speed mode. (5). In the image forming apparatus described in (1), (2), (3) or (4), the fixing device is detachable from the main body of the image forming apparatus. (6). The image forming apparatus according to (1), (2), (3), (4) or (5), further comprising a clear unit for erasing information stored in the non-volatile storage medium, and By operating the clearing means, the information stored in the non-volatile storage medium is erased, and the warning of the abnormal situation by the warning means is canceled (claim 6).

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [1] Overall Configuration of Image Forming Apparatus and Image Forming Process In FIG. 1 showing a cross section of a main part of a digital image forming apparatus suitable for carrying out the present invention, reference numeral 1 denotes a rotating body. It shows a drum-shaped photoconductor as an example of an image carrier. Around the photoreceptor 1, a charging device 2 composed of a charging roller, a mirror 3 constituting a part of an exposure unit, and a developing roller 4 are arranged in the clockwise direction indicated by an arrow in the rotational direction.
a transfer means 5 for holding and conveying a transfer sheet S as a recording medium, a cleaning means 6 having a blade 6a for slidingly contacting the peripheral surface of the photoconductor 1, and the like. Exposure light Lb is scanned via a mirror 3 at a position on the photoreceptor 1 between the charging device 2 and the developing roller 4a. This exposure light Lb
Is referred to as an exposure unit 15.

The transfer / transport belt 5 is an endless belt, and is supported by two support rollers 5a and 5b. The lower surface of the photoreceptor 1 is in contact with an intermediate position of the transfer conveyance belt 5 supported by the support rollers 5a and 5b.
The contacting portion is a transfer portion 7, and a transfer roller 8 as a transfer unit for applying a transfer bias is provided on the back side of the transfer conveyance belt 5 in the transfer portion 7.

The transfer / transport belt 5 is driven to rotate counterclockwise as indicated by the arrow. A pair of registration rollers 9 is provided at a position further upstream of the upstream end of the upper belt portion of the transfer conveyance belt 5.
The transfer paper S stored in a paper feed tray (not shown) guided by a transport guide (not shown) is fed from the paper feed roller 11 toward the registration roller 9. At a position further downstream of the downstream end of the upper belt portion of the transfer conveyance belt 5, a fixing device 12 is disposed.

At the upstream end of the upper belt portion of the transfer / transport belt 5, above a support roller 5 a supporting the transfer / transport belt 5, a brush as suction means is brought into contact with the transfer / transport belt 5 so as to contact the transfer / transport belt 5. The roller 20 is provided so as to be driven to rotate clockwise as indicated by an arrow.

When the brush roller 20 rotates, the brush comes into sliding contact with the transfer / conveying belt 5. A potential for applying a bias current having a polarity to attract the transfer paper S to the transfer conveyance belt 5 is applied to the brush roller 20 by a bias application unit (not shown).

In this image forming apparatus, image formation is performed as follows. The photoreceptor 1 starts rotating, and during this rotation, the photoreceptor 1 is uniformly charged by the charging device 2 in the dark, and the exposure unit 15 irradiates the exposure unit 15 with the exposure light Lb and scans the latent image corresponding to the image to be created. It is formed. This latent image reaches the developing device 4 by the rotation of the photoconductor 1, where it is visualized by toner to form a toner image.

On the other hand, the feeding of the transfer paper S on the paper feed tray by the paper feed roller 11 is started, and is temporarily stopped at the position of the pair of registration rollers 9 via the transport path shown by the broken line, and
The timing of sending out the toner image is waited so that the toner image coincides with the upper toner image in the transfer unit 7. When such a suitable timing comes, the transfer paper S stopped at the registration roller 9 is sent out from the registration roller 9.

The transfer paper S sent out from the registration roller 9 is held between the transfer / transport belt 5 and the brush roller 20, pressed by the electrostatic force of the bias and the elastic force of the brush, and attracted to the transfer / transport belt 5, The transfer belt 5 is conveyed toward the transfer section 7 with the movement.

The toner image on the photosensitive member 1 and the transfer paper S coincide with each other at the transfer section 7, and are transferred by the transfer roller 8 to the transfer conveyance belt 5.
The toner image is transferred onto the transfer sheet S by an electric field formed from the bias applied to the photosensitive member 1 and the potential difference between the photosensitive member 1.

The transfer paper S carrying the toner image in this manner is conveyed together with the transfer conveyance belt 5, and is separated from the transfer conveyance belt 5 at the downstream end of the upper part of the transfer conveyance belt 5 before being sent out to the fixing device 12. It is. The toner image on the transfer sheet S is fixed to the transfer sheet S while passing through the fixing device 12, and is discharged to a discharge section (not shown).

On the other hand, the residual toner remaining on the photoreceptor 1 without being transferred by the transfer unit 7 reaches the cleaning device 6 with the rotation of the photoreceptor 1 and is cleaned while passing through the cleaning device 6 to clean the next image. Be prepared for formation. [2] Configuration of Fixing Device The configuration of the fixing device will be described with reference to FIG. As shown in FIG. 2, the fixing device 12 has a configuration in which an upper fixing roller 22 having a built-in heat source lamp 21 and a lower fixing roller 24 having a built-in heat source lamp 23 are pressed against each other.

A thermistor 25 for detecting the surface temperature of the fixing roller 22 is brought into contact with the peripheral surface of the fixing roller 22 so that the surface temperature of the fixing rollers 22 and 23 heated by the heat source lamps 21 and 23 is controlled. It is designed to detect. The temperature information as the output of the thermistor 25 is input as an output from sensors 27 in FIG. 4 to a CPU 26 as a control means for controlling the operation of the image forming apparatus. The CPU 26 compares the temperature information with a reference value to monitor the presence or absence of an abnormality, and controls the temperature to a predetermined fixing temperature by a fade-back control.

The fixing device 12 has a non-volatile storage medium 32 as storage means for storing information unique to the fixing device 12. This non-volatile storage medium 32
A non-volatile memory having a backup by an EEPROM or a battery is used, and reading and writing are also possible.

As shown in FIG. 3, when the fixing device 12 is mounted on the image forming apparatus main body 28, a connector 29a provided at the distal end of the lead wire 29 of the nonvolatile storage medium 32; The connector 31a provided at the tip of the lead wire 31 connected to the CPU 26 mounted on the apparatus main body 28 is in a connected state.

Thus, the information specific to the fixing unit 41 stored in the non-volatile storage medium 32 is read by the CPU 26 of the apparatus main body 28, and control according to the read information can be performed. Also, information can be sent from the CPU 26 to the non-volatile storage medium 32 and stored in the non-volatile storage medium, which can be used as needed.

The CPU 26 determines whether or not the frequency of use of the fixing device 12 stored in the non-volatile storage medium 32 has reached a value corresponding to the life of the fixing device 12, and can perform processing in accordance with the judgment. .

In FIG. 2, a nonvolatile storage medium 32 is mounted on a substrate 33 together with a thermistor 34. The non-volatile storage medium 32, the thermistor 34, and the like are installed in a heat insulating chamber 36 separated from the fixing rollers 22 and 24 in the fixing device 12 by a heat insulating wall 35, and are affected by heat from the fixing rollers 22, 24 and the like. Is not reached.

When the peripheral temperature of the substrate 33 becomes equal to or higher than a predetermined temperature, the temperature is detected by the thermistor 34 and the cooling fan 37 is driven to place the nonvolatile storage medium 32 in a predetermined appropriate temperature environment.

The fixing device 12 is detachable from the apparatus main body 28. For this attachment and detachment, the fixing device 12
As shown in FIGS. 2 and 3, it can be inserted and removed along a guide rail 38 provided on the apparatus main body 28.

In FIG. 3, an approximate boundary line AA
The area indicated by the arrow pointing to the right is the fixing device side, and the area indicated by the arrow pointing left from the boundary line AA is the area on the apparatus main body side. When removing the fixing device 12 from the apparatus main body 28, the fixing device 12 is pulled out in a direction indicated by an arrow 39 along a guide rail 38 on the apparatus main body 28 side.

With the operation of the drawer, the connector 29
The connection states of a and 31a are released. When the fixing device 12 is mounted on the apparatus main body 28, the connectors 29a and 31a are connected in accordance with the mounting operation, which is the reverse of the above. [3] Configuration of Control System A control system of the image forming apparatus will be described with reference to FIG. In FIG. 4, the image forming apparatus main body 28 includes a controller 40 for performing image processing, a so-called engine 41 including the photoreceptor 1 for actually forming an image and its peripheral members, an engine control board 42 for controlling the engine 41, and an operation panel. 43 and others.

As shown in FIG. 5, various switches 51 for operating the image forming apparatus, a liquid crystal panel 52 capable of displaying figures and character information, and a nonvolatile storage medium 32 are stored on the operation panel 43. A clear button 53 (see FIG. 5), which is an operation button for clearing the information, is provided.

A control system in the image forming apparatus main body 28 includes an input / output interface 4 of an engine control board.
4. ROM in which engine control programs are stored
45, a ROM 45 programmed with an operation sequence of the image forming apparatus, a CPU 26 for controlling the entire engine 41 by a mode instruction from the operation panel 43 and a command from the controller 40, a work memory of the CPU 26, and a RAM 46 as an input buffer for input data. A nonvolatile storage medium 54 of EEPROM for storing the error history of the engine and the contents of the mode instruction from the operation panel, a dip switch 47 for setting an engine control mode, a laser diode as an exposure unit, and a polygon as a scanning unit A writing unit 48 including a motor and the like, a sequence device group 49 for controlling the fixing device 12, the developing means 4, and a drive system, various sensors 27 for checking a passing state and a sequence state of the transfer paper S, and individual information of the fixing device 12 Store Nonvolatile storage medium 32, there is output interface 50 or the like between the host computer 49 and the controller 40. [4] Examples corresponding to the claims Examples of Claims 1, 5, and 6 Thermistor 25 as temperature detecting means for detecting a temperature by a heat source such as the heat source lamps 21 and 23, and the thermistor 25
CPU 26 as control means for determining whether or not the fixing temperature in fixing device 12 is abnormal based on temperature information from
The nonvolatile storage medium 42 that is provided in the fixing device 12 and stores this abnormality information when the CPU 26 determines that there is an abnormality has already been described. CPU26
The liquid crystal panel 52 provided on the operation panel 43 provided in FIGS. 4 and 5 corresponds to a warning means for displaying a warning when it is determined that there is an abnormality.

In the present invention, the CPU 26 controls the heat source lamp 2
If the CPU 26 determines that the feedback control system using the thermistor 25 has a failure or failure due to a failure of the thermistor 1, 23 or the like, or the thermistor 25, etc. First of all, errors occur, and in the worst case, there is even a risk of fire.
The energy supply to the heat source lamps 21 and 23, that is, the power supply is cut off, and then the warning information is displayed on the liquid crystal panel 52. At the same time, the information indicating that there is an abnormality is stored in the nonvolatile storage medium 32. When it is deemed that such visual warning information alone is not sufficient, a warning buzzer is provided, and by sounding the warning buzzer, the warning is more surely provided.

Heat source lamps 21 and 23 or thermistor 2
The detection of the above-mentioned abnormality due to the occurrence of a defect, failure, or the like in 5 etc. is based on the fact that the CPU 26 monitors the temperature information from the thermistor 25 in the program sequence and detects a deviation of a certain level abnormality from an appropriate state. This is done by detecting.

As described above, by issuing the warning information, it is possible to notify the operator (or service person) of an emergency, thereby avoiding a situation such as a fire or a fixing error. The service person removes the fixing device 12 from the image forming apparatus main body 28. At that time, the connector 29a,
Although the connection between 31a is broken, the information stored in the non-volatile storage medium 32 does not disappear.

The serviceman repairs the anomaly of the thermistor 25 or the heat source lamps 21 and 23 in the fixing device 12, but at this time, since the power supply has been already cut off, the safety of work is secured. After completion of the repair, the fixing device 12 is mounted on the image forming apparatus main body 28, and the connectors 29a, 31
a are connected, and the clear button 53 is pressed. Thereby, the storage of the abnormal situation regarding the temperature of the fixing device stored in the nonvolatile storage medium 32 for the first time is deleted.

That is, in the fixing device which is detachable from the main body of the image forming apparatus in order to ensure the safety of the work, the abnormal situation is stored in the non-volatile storage medium 32. Unless the clear button 53 is pressed positively, the warning display of the abnormal situation is not canceled, so that the certainty of the abnormal situation processing is ensured.

In the present invention, for example, the processing at the time of abnormality due to a fixing low temperature error is performed according to the flow shown in FIG. Alternatively, the processing for the thermistor abnormality is performed according to the flow shown in FIG.

In FIG. 6, it is determined in step P1 whether a low-temperature fixing error has occurred. That is, when the temperature does not reach the predetermined fixing temperature although it should have reached the predetermined fixing temperature, it is determined that a fixing low temperature error has occurred, and the routine goes to Step P2.

In step P2, an operation to cut off the power supply to the heat source lamps 21 and 23 of the fixing device 12 is performed, and the process goes to step P3. In step P3, the liquid crystal panel 52
"Low temperature error" and "Fixing low temperature error: Please contact a service person" are displayed, and the routine goes to Step P4. In Step P4, the low-temperature fixing error information is stored in the nonvolatile storage medium 32.

Although the flow of FIG. 6 has been completed up to this point, as a subsequent procedure, as described above, the serviceman removes the fixing device 12 from the image forming apparatus main body 28 and repairs it. By attaching the fixing device 53 to the forming apparatus main body 28 and pressing the clear button 53, the record of the abnormal situation regarding the temperature of the fixing device stored in the nonvolatile storage medium 32 is deleted.

In the present invention, for example, a process when the thermistor is abnormal is performed according to the flow shown in FIG.

In FIG. 7, it is determined in step Q1 whether a thermistor abnormality has occurred.

If it is determined in step Q1 that a thermistor abnormality has occurred, the operation proceeds to step Q2. Step Q3 following step Q2, step Q4
Corresponds to step P3 and step P4 in FIG. 6, respectively, and the processing contents are the same, and the same applies to the subsequent treatment by the service person.

The determination of the thermistor abnormality in step Q1 is made by the CPU 26. The determination as to whether or not the low-temperature fixing error has occurred in step P1 in FIG. 6 may be performed including the determination as to whether or not the thermistor abnormality has occurred in step Q1 in FIG. The image forming apparatus forms an image with dots based on digital information, and when the resolution of the image can be switched, for example, an image of 600 dpi and two resolution outputs of 12000 dpi are output. If possible, image formation at a resolution of 1200 dpi is called a low-speed mode, and the feed speed of the transfer sheet S in the low-speed mode is の of the feed speed of the transfer sheet S during image formation in the high-speed mode at a resolution of 600 dpi. .

In such an image forming apparatus, when the fixing paper is passed at a low speed of 1200 dpi, the resolution is 600 dpi.
Output at the same fixing temperature and nip width as at the time of high-speed paper passing at dpi results in over-fixing, which causes wrinkles on the printing paper. For example, when outputting at a low speed of 1200 dpi immediately after outputting at a high speed of 600 dpi,
Since the feed speed is halved, an excessive fixing temperature occurs. As described above, an appropriate fixing temperature of the toner cannot be obtained, and a problem occurs.

In this embodiment, in the image forming apparatus capable of switching between the low-speed mode and the high-speed mode, when the low-speed mode (when the low-speed mode is set), the heat source lamp 21 is used.
The supply current to the heat source lamps 21 and 23 is increased in the high-speed mode (when the high-speed mode is set). As a result, a fixing temperature suitable for the feeding speed of the recording paper S is obtained, and problems such as excessive fixing and unfixing are prevented. In this example, when the mode is switched from the low-speed mode to the high-speed mode, the heat source lamps 21 and 23 are changed from the low fixing temperature set for the low-speed mode to the high fixing temperature set for the high-speed mode. The supply of the recording paper S is not started until the current level applied to the recording paper S is switched to a high level and the fixing temperature rises to a predetermined fixing temperature suitable for the high-speed mode.

FIG. 8 shows an example of this. In the process, even if there is a paper feed request to the paper feed roller 11 or the registration roller 9, the fixing temperature is set to the resolution 60 in the high-speed mode.
If the predetermined fixing temperature corresponding to the normal linear speed conforming to 0 dpi has not been reached, the sheet feeding is not started, and when it is confirmed that the predetermined fixing temperature has been reached, the sheet feeding roller 11
In this case, the sheet feeding is started with the registration roller 9 in the function state and the fixing failure is avoided. In this example, when the mode is switched from the high-speed mode to the low-speed mode, the heat source lamps 21 and 23 are changed from the high fixing temperature set for the high-speed mode to the low fixing temperature set for the low-speed mode. The supply of the recording paper S is not started until the current level applied to the recording paper S is switched to a low level and the fixing temperature drops to a predetermined fixing temperature suitable for the low-speed mode.

FIG. 9 shows an example of this. In the process, even if there is a paper feed request to the paper feed roller 11 or the registration roller 9, the fixing temperature is set to the resolution 12 in the low speed mode.
1 at 600 dpi resolution conforming to 00 dpi
If the specified fixing temperature corresponding to the / 2 linear speed has not been reached,
If it is confirmed that the predetermined fixing temperature has been reached without starting the sheet feeding, the sheet feeding roller 11 or the registration roller 9
Is set to a functional state to start feeding, thereby avoiding a fixing failure.

[0050]

According to the first aspect of the present invention, when the temperature of the fixing device is abnormal, the supply of energy to the heat source is cut off first, so that it is possible to eliminate at least the danger such as ignition. Further, safety in repairing the fixing device is also ensured.

According to the second aspect of the present invention, a fixing temperature suitable for the transfer speed of the transfer medium can be obtained, and problems such as excessive fixing and non-fixing can be prevented.

According to the third aspect of the present invention, it is possible to avoid a defective fixing caused by a shortage of the fixing temperature. According to the fourth aspect of the invention, it is possible to avoid a fixing defect caused by an excessive fixing temperature.

According to the fifth aspect of the present invention, since the fixing device is detachable from the image forming apparatus main body, the safety of the repair work is ensured. According to the sixth aspect of the present invention, the reliability of the abnormality processing of the fixing device is ensured.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus suitable for carrying out the present invention.

FIG. 2 is a front view of the fixing device.

FIG. 3 is a diagram illustrating a configuration of a detachable unit of the fixing device with respect to the image forming apparatus main body.

FIG. 4 is a block diagram of a control system.

FIG. 5 is a front view of a main part of an operation panel.

FIG. 6 is a flowchart.

FIG. 7 is a flowchart.

FIG. 8 is a flowchart.

FIG. 9 is a flowchart.

[Explanation of symbols]

 12 Fixing Device 25 Thermistor 26 CPU 32 Non-Volatile Storage Medium 52 Liquid Crystal Panel

Claims (6)

[Claims] An image forming apparatus provided with a fixing device for fixing a toner image carried on a recording medium at a fixing temperature set by heating with a heat source; temperature detecting means for detecting a temperature by the heat source; A control unit that determines whether there is an abnormality in the fixing temperature in the fixing device based on temperature information from the detection unit; and an abnormality when the control unit determines that the abnormality is present in the fixing device. A non-volatile storage medium for storing information; and a warning unit for displaying a warning when the control unit determines that the abnormality is present. When the control unit determines that the abnormality is present, first, ,
An image forming apparatus, wherein the supply of energy to the heat source is interrupted, and then information indicating that there is an abnormality is stored in the nonvolatile storage medium, and a warning of an abnormal situation is issued by the warning unit. 2. The image forming apparatus according to claim 1, wherein a low-speed mode in which a feeding speed of the recording medium in the fixing device is low, and When the speed of the recording medium can be switched to any one of a high-speed mode and a high-speed mode, it is controlled to lower the temperature of the heat source in the low-speed mode and increase the temperature of the heat source in the high-speed mode. Characteristic image forming apparatus. 3. The image forming apparatus according to claim 2, wherein when the mode is switched from the low speed mode to the high speed mode, a low fixing temperature set for the low speed mode is set to a high fixing temperature set for the high speed mode. An image forming apparatus that switches an energy supply level to the heat source so as to reach a temperature and does not start feeding the recording medium until the fixing temperature rises to a predetermined fixing temperature suitable for the high-speed mode. 4. The image forming apparatus according to claim 2, wherein when the high-speed mode is switched to the low-speed mode, a high fixing temperature set for the high-speed mode is set to a low fixing temperature for the low-speed mode. An image forming apparatus that switches an energy supply level to the heat source so as to reach a temperature, and does not start feeding the recording medium until the fixing temperature falls to a predetermined fixing temperature suitable for the low-speed mode. 5. The image forming apparatus according to claim 1, wherein said fixing device is detachable from said image forming apparatus main body. 6. An image forming apparatus according to claim 1, further comprising a clearing unit for erasing information stored in said nonvolatile storage medium, wherein said control unit controls said clearing unit. An image forming apparatus, wherein the information stored in the non-volatile storage medium is erased by an operation, and the warning of the abnormal situation by the warning means is released.