JPH03242675A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent erroneous detection with reference to the abnormality of a fixing device which arises in the case that an image is formed again after images are continu ously formed by performing an abnormality discriminating mode for discriminating the abnormality of the fixing device only in the case that the temperature of a heating body at the time of starting to energize the heating body is equal to or below a pre scribed temperature. CONSTITUTION:The detection signal of a temperature detecting element 24 for detecting the temperature of the heating body 21 is always monitored by a microcomputer in the device. And, in the case that the temperature of the heating body 21 at the time of starting to enertgize the heating body 21 is equal to or below the prescribed temperature, for example, 150 deg.C, this state is decided as the abnormality of the fixing device caused by the disconnection, etc., of the temperature of the temperature detecting element 24. And, in the case that the temperature of the heating body 21 does not reach 150 deg.C after the lapse of prescribed time, this state is decided as the abnormality of the fixing device, and then, the abnormality of the fixing device is displayed. In the case that the temperature of the heating body 21 reaches 150 deg.C after the lapse of prescribed time, a series of actions necessary for forming the image is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming apparatus having a fixing means for heating and fixing a visible image onto a recording material.

[Prior Art] Conventionally, a heating device for a recording material, for example, for heat fixing an image, uses a heating roller maintained at a predetermined temperature and a pressure roller having an elastic layer and pressed against the heating roller. , a constant fixing method using heated rollers that heats the recording material while nipping and conveying it is often used.

A belt heating method is also known, as disclosed in US Pat. No. 3,578,797.

This is because: (1) the toner image is brought into contact with the heating web and heated to its melting point, (2) the toner is cooled to a relatively high viscosity after melting, and (2) the toner image tends to adhere to the heating web. Peel it off from the heating element web in a weakened state.

By going through this process, it is a method of fixing without causing offset.

Recently, fixedly supported heating elements (thermal heaters,
(hereinafter referred to as a heater), and a pressure member that brings the recording material into close contact with the heater via a heat-resistant film that is conveyed while being in pressure contact with the heater, and applies heat from the heater to the recording material via the film. JP-A No. 63313 discloses a fixing device (film heating method) having a method and structure for heating and fixing an unfixed image formed and carried on the recording material surface onto the recording material surface.
This is proposed in Publication No. 182.

In a film heating method using such a thin film, a low heat capacity heating element can be used as a heater. Therefore, it is possible to save power and shorten wait time (quick start) compared to conventional contact heating methods such as the heat roller method and the heald heating method.

In addition, it has the advantage of being able to solve various drawbacks of conventional heating methods, and is therefore effective.

[Problem to be solved by the invention] By the way, in the above conventional example, disconnection of the low heat capacity heating element,
Fixing unit abnormalities may occur due to poor contact of the temperature detection element that detects the temperature of the heating element, disconnection of the temperature detection element, and the like.

In order to detect this fuser abnormality, if the temperature of the heating element after a predetermined period of time has elapsed since the start of power supply to the heating element is equal to or lower than the temperature of the heating element at the start of power supply, or if the temperature rise value is significantly lower In this case, it may be determined that there is an abnormality in the fixing device.

However, immediately after continuous image formation for a long time, the temperature of the heating element does not drop sufficiently even if the power supply is cut off, and if image formation is started again at this time, the temperature of the heating element Since there is almost no difference in temperature between the temperature and the temperature of the heating element after a predetermined period of time has elapsed, an abnormality in the fixing device may be mistakenly detected when the abnormality in the fixing device is detected.

Means for Solving Problem E] The present invention for solving the above problems includes an image forming means for forming a visible image on a recording material, a heating body, and a film that moves together with the recording material. In an image forming apparatus that includes a fixing unit that heats a recording material supporting a visible image via a film using heat from a heating body, and starts supplying power to the heating body after an image formation start command, the heating It has an abnormality determination mode that determines an abnormality in the fixing device based on the quality of the heating element 7 after a predetermined period of time after the start of energization to the heating element. It is characterized in that it is executed only when the

[First Example] Hereinafter, a first example of the present invention will be described based on the accompanying drawings.

A first embodiment is shown in FIGS. 1 to 5.

First, the general structure of the image forming apparatus of this embodiment will be explained based on FIG. 1. Reference numeral 1 denotes a document mounting table made of a transparent member such as glass, which scans the document by reciprocating in the direction of arrow a. A short-focus small-diameter imaging element array 2 is located directly below the document table.
The document image placed on the document table is irradiated by a fluorescent lamp 3, and the reflected light image is slit-exposed onto the photosensitive drum 4 by the array 2. Note that this photosensitive drum 4 rotates in the direction of the arrow. A charger 5 uniformly charges the photosensitive drum 4 coated with, for example, a zinc oxide photosensitive layer or an organic semiconductor photosensitive layer. The tram 4 charged by the charger 5 is subjected to image exposure by the element array 2 to form an electrostatic image. This electrostatic image is visualized by a developing device 6 using toner made of a resin or the like that softens and melts when heated. On the other hand, the sheet P stored in the cassette S is
The image is fed onto the drum 4 by a pair of conveyance rollers 8 which are rotated while pressing against each other in the vertical direction in synchronization with the feed roller 7 and the image on the photosensitive drum 4 . Then, the toner image formed on the photosensitive drum 4 is transferred onto the sheet P by the transfer discharger 9. Thereafter, the sheet P separated from the drum 4 by a known separation means is guided to a fixing device 11 by a conveyance guide 10, heated and fixed, and then discharged onto a tray 13. In addition,
After transferring the toner image, residual toner on the drum 4 is removed by a cleaner 12. FIG. 2 shows an enlarged view of the fixing device 11 of this embodiment. 21 is a low heat capacity linear heating body fixedly supported by the device, and has a thickness of 1.0 mm as an example.
A heating resistor material 23 is mounted on an alumina substrate 22 made of ceramic with good thermal conductivity and having a width of 10 mm and a longitudinal length of 270 mm.
It is coated with a width of 1.5 mm and is energized from both ends in the longitudinal direction. The current is applied in a pulse-like waveform of DClooV with a period of 20 m5 ec, and a pulse corresponding to the desired amount of thermal energy released controlled by the temperature measuring element 24 is given by changing the pulse width. Approximate pulse width is 0.5m5ec~5
It becomes m5eC. In this way, the fixing film 25 is brought into contact with the heating body 21 whose energy and temperature are controlled in the direction of the arrow in the figure.
moves. As an example of this fixing film, the thickness is 20 μm.
Pure heat-resistant heath film without mixed fillers, such as polyimide, polyetherimide, PES
, PFA with PTFE and PAF at least on the image contact side
It is an endless film coated with a release layer made of a fluororesin such as fluororesin with a conductive material added thereto, R< t o μm from a heat-resistant heath film. In order to reduce heat capacity and achieve quick start, the total thickness of the film is less than 100 μm.
More preferably, it is less than 40 μm.

The film is driven by the driving roller 26 and the driven roller 27 and tension to move the film in the direction of the arrow without wrinkles. Reference numeral 28 denotes a pressure roller having a rubber elastic layer having good mold releasability, such as silicone rubber, which presses the heating body through the film with a total pressure of 4 to 7 kg, and rotates in pressure contact with the film. sheet P
The unfixed toner T on the top is guided to the fixing section by the chromatograph 29, and a fixed image is obtained by the above-mentioned heating.

Although the explanation has been made using an endless belt, the fixing film may be a film with ends as shown in FIG. 2(b). Further, as image forming apparatuses, the present invention is applicable to all types of fixing devices that form images using toner, such as copying machines, printers, and fax machines.

Next, FIG. 3 shows a control block diagram. First 4
Reference numeral 0 denotes a control means, which in this embodiment is comprised of a microcomputer, logic elements, and the like. An image leading edge signal from an image edge detecting means 45 that detects an image edge timing signal from an image edge timing member (not shown) attached to the original document mounting table 1 is connected to an input terminal INl of the control means 40 . Similarly, the input terminal IN2 receives a signal from the paper ejection sensor 16 on the paper ejection side of the fixing device in the paper conveyance direction.
The paper output sensor signal is connected. Also, the control means 40
A fixing temperature adjustment permission signal is outputted from the 0UTI terminal of the heating element 21 to the temperature control means 41 that controls the temperature of the heating element 21. Further, a temperature signal from a temperature measuring element 24 attached near the heating body 21 is connected to an input terminal ADINI terminal.

The 0UT2 terminal outputs a transport drive signal to the drive motor 42 which drives the image forming apparatus and the aforementioned fixing film. A paper feed drive signal to the paper picture drive unit 43 is output from the 0UT3 terminal. A conveyance roller drive signal to the conveyance roller drive section 44 is output from the 0UT4 terminal. 47 is a fluorescent lamp driving means, a fluorescent lamp filament preheating signal is connected to the 0UT5 terminal, and the 0UT
A fluorescent lamp lighting device is connected to terminal 6 to drive the fluorescent lamp 3. Also, a light amount detection element 4 placed near the fluorescent lamp 3
The light amount signal from 6 is connected to the ADIN2 terminal.

Although not shown, other human input signals and output signals necessary for the operation of the image forming apparatus are provided, and the control means 4
The microcomputer in RO is programmed with the operation sequence program of this image forming apparatus.
In addition to M and RAM, a non-volatile RAM whose stored contents will not be erased even if the power supply to the microcomputer 40 is cut off is built-in.

4 and 5 show schematic flowcharts of the operation sequence program of this embodiment. This program is stored in the built-in ROM of the microcomputer in the control means 40 mentioned above.
After the device operates, step 1 is executed from the start. Step 1
In this step, it is determined whether or not the error information bit in the nonvolatile RAM is 1. If this bit is O, the process moves to step 3, and if it is 1, the process moves to step 2. In step 2, the error code No. is set to "1" and the process moves to step 23. In step 3, it is determined whether or not a copy start button (not shown) has been pressed, that is, whether or not to start image formation.If it does not start, the process returns to step 3 and enters a so-called standby state.

Furthermore, if image formation is to be started in step 3, the process will proceed to step 4. Step 4: To start the image forming operation, first turn on the drive motor 42, then turn on the fluorescent lamp filament preheating signal,
Next, read the initial crystallinity of the heating element 21 from the crystal element 24, store the salinity in a predetermined RAM, then turn the fixing temperature adjustment permission signal ONL, start the 3 second timer, and step 5 Move to. In step 5, it is determined whether the aforementioned 3 second timer has elapsed or not. If 3 seconds have elapsed, proceed to step 6; if not, return to step 5 and wait for 3 seconds to elapse. become. In step 6, it is determined whether the initial temperature of the heating element 21 read in step 4 is 150°C or higher. If it is 150°C or higher, the process moves to step 9, and if it is 150°C or lower, the process moves to step 7. Transition. In step 7, the temperature of the heating element 21 from the temperature sensing element 24 is read and compared with the initial temperature.If the temperature of the heating element 21 is higher than the initial temperature, that is, if the temperature of the heating element 21 is still rising, step If this is not the case, that is, if the temperature of the heating element 21 has not been raised, the process moves to step 8. In step 8, the error code No. is set to "2" and the process moves to step 23.

Next, in step 9, the fluorescent lamp filament preheating signal is
At the same time as the FF is turned on, the fluorescent lamp lighting signal is turned on to turn on the fluorescent lamp, and the process proceeds to step 10. In step 10, the paper feed drive signal SLI is used to feed the ONL sheet P until it hits the conveyance roller 8, and the process moves to step 11. In step 11, the original table 1 is moved to the image exposure start position, and the process proceeds to step 12. In step 12, it is determined whether the light intensity of the fluorescent lamp 3 from the light intensity detection element 46 has reached a predetermined scene. It is necessary to wait until the amount of returned light reaches a predetermined amount of light. In step 13, image exposure is started and the process moves to step 14. In step]4, the image tip detection means 4
It is determined whether the image tip signal R from step 5 is ON or not. If it is not ON, the process returns to step 14 and the image tip signal R is turned on.
This will be repeated until it turns ON. Next, if the image tip signal R is ONI, the process moves to step 15.

In step 15, the conveyance roller drive signal SL2 is turned ON.
At the same time as the conveyance of sheets L and P is started, a 3-second timer is started, and the process moves to step 16. Step 16
Here, it is determined whether or not the 3 second timer has elapsed. If 3 seconds have elapsed, that is, in this embodiment, if the timing is immediately before the sheet P enters the fixing device 11, the process moves to step 17. , otherwise step 16
You will have to go back and wait for 3 seconds to pass. Step 17
In this step, the temperature of the heating element 21 from the thermometer 24 is read, and it is determined whether the temperature is 180°C or higher. If the temperature is 180°C or higher, the process moves to step 19 and the temperature is 180°C or higher.
If the temperature is below .degree. C., the process moves to step 18. Step 18
Then, set the error code No. to "3" and proceed to step 23. Next, in step 19, a series of other operations necessary for image formation are performed at predetermined timing, and the process proceeds to step 20. In step 20,
It is determined whether the paper discharge sensor signal is OFF or not. If it is not OFF, the process returns to step 20 and waits until the sheet P passes the paper discharge sensor 16. Further, in step 20, if the paper discharge sensor signal is OFF, the process moves to step 21. In step 21, it is determined whether or not to continue to form the next image.If the next image is to be formed, step 1
It returns to 0 and repeats the above-mentioned operation. Further, in step 21, if the next image formation is not to be performed, that is, when the image formation is completed, the process moves to step 22,
After setting the fixing temperature adjustment permission signal to 0FFL and performing post-image forming processing such as removing the charge on the photosensitive drum 4, the drive motor 42 is set to 0FFL and the process returns to step 3.

What is shown in FIG. 5 is a flowchart of error processing. In step 23, it is determined whether the error code NO is "3". If it is 3, the process moves to step 25; otherwise, Proceed to step 24. In step 24, 1 is written to the error information bit in the nonvolatile RAM, and the process moves to step 25. In step 25, all outputs and drives of the device are turned off, and the process moves to step 26. In step 26, an abnormality of the fixing device is displayed, and step 26 becomes an endless loop, so that other programs cannot be executed.

As described above, by using the image forming apparatus configured in this embodiment, when the copy start button is pressed and image formation starts, fixing temperature control is started, and the fixing temperature at the start of image formation is Only when the quality of the fixing device 7 is below a predetermined temperature, when the quality of the fixing device 7 after a predetermined period of time is equal to or lower than the temperature at the start of image formation, and when the temperature increase value is significantly less (i.e. , when the fuser malfunctions due to a break in the heating element, a break in the temperature detection element, or poor contact of the detection element). If the next fixing 7 temperature control is started without the temperature decreasing, the temperature increase value in the fixing abnormality detection will be reduced, which has the effect of preventing erroneous fixing abnormality detection. In addition, if the temperature of the fuser does not reach the predetermined 7 quality levels after a predetermined time has elapsed since the sheet P started to be conveyed, that is, immediately before it enters the fuser, it is determined that the fuser is abnormal, thereby preventing fixing failure or offset. It has the effect of preventing In addition, the cause of the fuser abnormality at this time is due to a drop in the power supply voltage that is the power supply source to the heating element 21, and is not due to a failure of the fuser itself. (in other words, without writing to non-volatile RAM),
When the power supply voltage returns to normal, the device can be used again, which has the effect of improving operability. Also,
In the case of any other abnormality in the fixing device, maintaining the abnormal state of the fixing device (that is, writing to the non-volatile RAM) has the effect of increasing the safety of the apparatus.

[Second Embodiment] A second embodiment is shown in FIGS. 6 to 9. A second embodiment of the present invention will be described below based on the accompanying drawings. FIG. 6 shows a schematic structural diagram of the image forming apparatus of this embodiment, or the transfer paper feeding mechanism of the image forming apparatus described in the first embodiment is a manual paper feeding mechanism. 53 manual guides,
A paper feed sensor 51 that detects that transfer paper is manually fed, and a paper feed roller 52 that feeds the fed transfer paper until it hits the conveyance roller 8 are added or changed. Further, a fixing entrance sensor 52 is added to detect when transfer paper is conveyed to the entrance of the fixing device. The other parts are the same as those described in the first embodiment.

Next, FIG. 7 shows a control block diagram. First 5
0 is a control means, which in this embodiment is composed of a microcomputer, a logic element, and the like. An image leading edge signal from an image edge detecting means 45 that detects an image edge timing signal from an image edge timing member (not shown) attached to the original document mounting table 1 is connected to an input terminal IN11 of the control means 50. Similarly, a paper discharge sensor signal from a paper discharge sensor 16 on the paper discharge side of the fixing device in the paper conveyance direction is connected to the input terminal lNl2. Input terminal lN
A paper picture sensor signal from the paper feed sensor 51 is connected to 13.

The fixed population sensor f3 from the fixed population sensor 52 is connected to the input terminal IN14. Further, from 0UT11@ of the control means 50, a fixing heater temperature adjustment permission signal is outputted to the temperature control means 41 which controls the temperature of the heating body 21. Further, the temperature signal from the temperature measuring element 24 attached near the heating element 21 is input to the input terminal ADINII.
connected to the terminal. From the 0UT12 terminal, a transport drive signal is outputted to the drive motor 42, which drives the image forming apparatus and the aforementioned fixing film. 0UT
Terminal 13 outputs a conveyance roller drive signal to the conveyance roller drive section 44 . Reference numeral 47 denotes a fluorescent lamp driving means, to which a fluorescent lamp filament preheating signal is connected from the 0UT15 terminal, and a fluorescent lamp lighting signal is connected from the OUT16 terminal to drive the fluorescent lamp 3. In addition, the light amount signal from the light amount detection element 46 placed near the fluorescent lamp 3 is ADiNl 2
connected to the terminal. The microcomputer in the control means 50 is also equipped with other human input signals and output signals (not shown) necessary for the operation of the image forming apparatus.
The microcomputer 50 has a built-in ROM and RAM programmed with operation sequence programs and the like of the image forming apparatus, as well as a non-volatile RAM whose stored contents will not be erased even if the power supply to the microcomputer 50 is cut off.

8 and 9 schematically show the flowchart and steps of the operation sequence program of this embodiment. This program is stored in the iROM of the microcomputer in the control means 50 mentioned above.
After the device starts operating, step 101 is executed from the start. In step 101, it is determined whether or not the error information bit in the nonvolatile RAM is 1. If this bit is O, the process moves to step 103, and if it is l, the process moves to step 102.
Move to. In step 102, 11 is set to Ellacoat NO.
” is set and the process moves to step 123. Step】
03 The sheet P is set manually and the paper feed sensor 5
1 or ON, and if it is not ON, the process returns to step 103 and enters a so-called standby state.

Also, in step 103, the paper feed sensor 51 is turned ON.
In this case, the process moves to step 104. In step 104, in order to start the image forming operation, first the drive motor 42 is turned on, then the fluorescent lamp filament preheating signal is turned on, and then the initial temperature of the heating element 21 from the temperature measuring element 24 is read and the temperature is set to a predetermined value. Store in RAM,
Next, the fixing temperature adjustment permission signal is turned on, a 3 second timer is started, and the process moves to step 105. Step 105
In this case, it is determined whether or not the aforementioned 3 second timer has elapsed. If 3 seconds have elapsed, the process moves to step 106; otherwise, the process returns to step 105 and waits for 3 seconds to elapse. . In step 106, step 10
It is determined whether the initial temperature of the heating element 21 read in step 4 is 150°C or higher. If it is 150°C or higher, the process moves to step 109, and if it is 150°C or lower, the process goes to step 1.
Move to 07. In step 107, the temperature of the heating element 21 from the thermometer 24 is read and compared with the initial temperature. If the temperature here is higher than the initial temperature, that is, if the heating element 21 has already risen in temperature, the process advances to step 109. If the heating element 21 is not aligned, that is, if the temperature of the heating element 21 has not been increased, the process moves to step 108. In step 108, the error code No. is set to "2" and the process moves to step 123. Next, in step 109, the fluorescent lamp filament preheating signal is turned OFF, and at the same time, the fluorescent lamp lighting signal is turned ON.
L, the fluorescent lamp is turned on, and the process moves to step 110. In step 110, the original table 1 is moved to the image exposure start position, and the process proceeds to step 112. In step 112, it is determined whether the light amount of the fluorescent lamp 3 from the light amount detection element 46 has reached a predetermined light amount.
If the light intensity has reached the predetermined light intensity, the process moves to step 113; otherwise, the process returns to step 112 and waits until the light intensity reaches the predetermined light intensity. In step 113, image exposure is started and the process moves to step 114. Step 114
At this point, it is determined whether or not the image tip signal R from the image tip detection means 45 is ON. If it is not ON, the process returns to step 114 and is repeated until the image tip signal R is turned ON. Next, if the image tip signal R is ONt, the process moves to step 115. In step 115, the conveyance roller drive signal is ONL, conveyance of the sheet P is started, and the process moves to step 116. In step 116, it is determined whether or not the fixing entrance sensor 52 is turned on.
If this is the case, that is, if the sheet P has reached the inlet of the fixing device, the process moves to step 117; otherwise, the process returns to step 116 and waits until the sheet P reaches the inlet of the fixing device. In step 117, the temperature of the heating element 21 from the thermometer 24 is read and it is determined whether or not the temperature is 180°C or higher. If the temperature is 180°C or higher, the process moves to step 119, and if it is 180°C or lower, the process moves to step 119. The process moves to step 118. In step 118, the error code number is set to "3" and the process proceeds to step 123.

Next, in step 119, a series of other operations necessary for image formation are performed at predetermined timing, and the process proceeds to step 120. In step 120, it is determined whether or not the paper discharge sensor signal is OFF. If it is not OFF, the process returns to step 120 and waits until the sheet P passes the paper discharge sensor 16. Also step 1
If the paper discharge sensor No. 20 is OFF, the process moves to step 121. In step 121, it is determined whether or not the paper feed sensor 51h) is on. If it is on, that is, if the next image formation is to be continued, the process returns to step 110 and the above-described operations are repeated. Further, in step 121, if the paper feed sensor is OFF, that is, when image formation is completed, the process moves to step 122, and the fixing 7 temperature adjustment permission signal is set to 0FFL, and post-image formation processing such as removing the charge on the photosensitive tram 4 is performed. After this, the drive motor 42 is turned off and the process returns to step 103.

What is shown in FIG. 5 is a flowchart of error processing, and step 123 is an error code N.

is "3" or not, and if it is 3, the process moves to step 125; otherwise, the process moves to step 124.
Move to. In step 124, 1 is written to the error information bit in the nonvolatile RAM, and the process moves to step 125. In step 125, all outputs and drives of the device are turned off, and the process moves to step 126. In step 126, an abnormality of the fixing device is displayed, and in step 12
6 is set as an endless loop to prevent other programs from being executed.

As described above, by using the image forming apparatus configured in this embodiment, the sheet P can be manually set,
When image formation starts, fixing temperature control is started, and only when the fixing device 7 quality at the start of image formation is less than the predetermined 7 quality, the fixing device temperature after a predetermined period of time is set at the time when image formation starts. When the temperature is equal to or lower than the temperature of By determining the fuser abnormality, if the next fixing temperature adjustment is started without the temperature of the fuser decreasing, which occurs during re-copying immediately after continuous copying, the temperature increase value at the time of the fixing abnormality detection will be reduced. This has the effect of preventing erroneous fixing abnormality detection. Also, sheet P
When the temperature of the fuser is detected by the fuser entrance sensor 54, that is, the temperature of the fuser immediately before entering the fuser, or if the predetermined temperature has not been reached, the fuser is determined to be abnormal.
It has the effect of preventing fixing failure and offset. In addition, the cause of the fuser abnormality at this time is due to a drop in the power supply voltage that is the power supply source to the heating element 21, and is not due to a failure of the fuser itself. (in other words, without writing to the non-volatile RAM), the device can be used again when the power supply voltage returns to normal, thereby improving operability. In addition, in the case of any other abnormality in the fixing device, maintaining the abnormal state of the fixing device (that is, writing to the nonvolatile RAM) has the effect of increasing the safety of the apparatus.

[Third Embodiment FIG. 10 shows a block diagram of the control of the third embodiment. The control block diagram of the first embodiment shows the IN3 terminal and the 0UT7 terminal.
It has an additional terminal. The 0UT7 terminal of the microcomputer 140 is connected to the base terminal of the transistor Q1 via a current limiting resistor R1. The emitter of the transistor Q1 is connected to a +5V power supply, and one terminal of the collector is connected to a capacitor C1 via a diode D1 and a charging current limiting resistor R3. Next, the capacitor C1 is connected to the IN3 terminal of the microcomputer 140 via the input protection resistor R4. Furthermore, the microcomputer 140 does not include a nonvolatile RAM. Since the other configurations are the same as those in the first embodiment, their explanation will be omitted here.

Next, to explain the operation in this configuration, 0UT7
When a LOW signal is output to the terminal, the transistor Q1 is turned on and the capacitor C1 is charged. Even if the power to the device is turned OFF, the charge in capacitor 01 is maintained, so if the power is turned ON and then back to I
By reading the level of the N3 terminal, the same function as that of the non-volatile RAM in the first embodiment can be realized, that is, reading from the non-volatile RAM in the first embodiment is equivalent to reading from the IN3@ child. By writing to the non-volatile RAM as a LOW output to the 0UT7 terminal, the same operation becomes possible and the same effect can be obtained.

As described above, in the embodiments of the present invention, energization to the heating element is started at the start of image formation, or in the case of a heating element whose temperature rises quickly, energization to the heating element is started at the timing of passage of the recording material after the start of image formation. You may start.

[Effects of the Invention] As described above, according to the present invention, the temperature of the heating element after a predetermined period of time from the start of power supply to the heating element is equal to the temperature of the heating element at the start of power supply. Alternatively, if the temperature rise value is low or the temperature rise value is extremely low, the abnormality determination mode that determines that the fuser is abnormal can be executed only when the salinity of the heating element is below a predetermined temperature at the time when electricity starts flowing to the heating element. This has the effect of preventing erroneous fixation abnormality detection that occurs when re-forming an image immediately after formation. At the same time, it also has the effect of improving operability.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the image forming apparatus according to the first embodiment, FIG. 2 is an enlarged sectional view of the fixing device, and FIG. 3 is a block diagram schematically showing the electrical configuration of the first embodiment. , FIG. 4 and FIG. 5 are flowcharts showing the outline of control in the first embodiment. FIG. 6 is a sectional view of the image forming apparatus according to the second embodiment. FIG. 2 is a block diagram schematically illustrating an example electrical configuration. 8 and 9 are flowcharts showing an outline of control in the second embodiment, and FIG. 10 is a block diagram showing an outline of the electrical configuration of the third embodiment.

Claims (1)

[Claims] It has an image forming means for forming a visible image on a recording material, a heating body, and a film that moves together with the recording material, and the recording material that supports the visible image via this film is heated by the heat from the heating body. In an image forming apparatus having a fixing unit that starts supplying power to a heating body after an image formation start command, an abnormality in the fixing device is determined based on the temperature of the heating body after a predetermined time from the start of energization to the heating body. It has an abnormality determination mode that
The image forming apparatus is characterized in that this abnormality determination mode is executed only when the temperature of the heating element at the start of energization to the heating element is equal to or lower than a predetermined temperature.