JP2003345168A - Fixing device and image forming apparatus provided with the fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device that can prevent an excessive rise of temperature in a non paper passing region of a heating body while achieving improvement of fixing property for a small sized paper without the enlargement of the device or the occurrence of a fixing failure, and an image forming apparatus provided with the fixing device. <P>SOLUTION: A recording material discriminating means discriminating the width size in a direction orthogonal to the carrying direction of recording material P is provided. A set temperature lowering mode is provided in which the set temperature of a heater 1 is set lower than when the width size is longer than the specified length when width size discriminated by the recording material discriminating means is shorter than the specified length. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an image forming apparatus such as a copying machine, a laser beam printer, and a FAX, which employs an electrophotographic method, and an image forming apparatus including the fixing device.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, a laser beam printer, and a FAX, which employs an electrophotographic method, for example, a photosensitive drum, which is an image carrier uniformly charged by a charging means, is used. Exposure light is irradiated on the surface in accordance with an original image or an image signal input to a computer or the like to form an electrostatic latent image, the electrostatic latent image is developed into a toner image by a developing device, and the toner image is transferred. 2. Description of the Related Art There is known an image forming apparatus in which a transfer roller, which is an apparatus, transfers a toner image on a recording material by a fixing device, and the toner image on the recording material is fixed on the recording material and output.

In such an image forming apparatus, as the fixing device, a heat generating member which is a heating member is brought into sliding contact with a fixing film which is a heat resistant film member, and a heating member which is a pressing member is applied to the heat generating member through the fixing film. A fixing device of a film fixing system is used which applies heat energy from a heat generating member through a fixing film to a recording material which is nipped and conveyed by the movement of a fixing film at a pressure contact portion which is a nip formed by pressing a pressure member. ing.

In this film fixing type fixing device, since the heater as a heat generating member and the fixing film as a member for transmitting the heat energy of the heater to the recording material can have a low heat capacity, power saving and reduction of wait time can be achieved. There is an advantage that it can be realized (quick start).

[0005]

However, in the above-mentioned conventional film fixing type fixing device, the following problems may occur.

In such a fixing device, in order to fix each of a plurality of types of recording materials having different width dimensions in the direction perpendicular to the conveying direction of the recording material, a recording material having a long width dimension (hereinafter, referred to as a large It is a general practice to set the fixing conditions of the fixing device so that sufficient fixing property can be secured even for size paper.

In such a case, when a recording material having a short width (hereinafter referred to as small size paper) is fixed, the temperature of the heat generating member in a portion (non-sheet passing area) where the small size paper does not pass is small. There is a possibility that a problem (hereinafter referred to as non-sheet-passing portion temperature rise) that the temperature of the heat-generating member in a portion through which the size sheet passes (sheet-passing region) becomes considerably higher.

When such a non-sheet-passing temperature rise occurs, the service life of the fixing device parts, such as the fixing film and the pressure roller, may be significantly shortened, and in the worst case, the fixing device parts may be damaged. There is a risk of.

Therefore, as the temperature detecting means for detecting the temperature of the heat generating member, in addition to the temperature detecting means for detecting the temperature of the central portion of the heat generating member in the paper passing area, the right angle of the non-paper passing area. Another temperature detecting element is also provided at the end of the direction, and when the temperature detected by this other temperature detecting element exceeds a certain temperature, the power supply from the power source to the heat generating member is also interrupted. Has been.

However, it is difficult to provide a plurality of temperature detecting elements, especially for a small fixing device.

Further, in order to release the heat generated by the temperature rise of the non-sheet passing portion to the outside of the apparatus, a method of installing a member having a large heat capacity in the fixing device is used.

For example, a metal roller is brought into contact with a fixing film, a pressure roller, or the like to return the heat generated by the temperature rise in the non-sheet-passing area to the sheet-passing area at the time of passing a small-sized sheet, so that the fixing device as a whole is lengthwise This is a method for trying to make the heat distribution in a uniform direction. In addition, there is also a method of installing a metal having a large heat capacity in the longitudinal direction in the vicinity of the fixed linear heating element.

However, these methods increase the size of the apparatus and deprive the heat of the heater, so that there is a risk of causing improper fixing or the like especially at the start-up at a low temperature.

Therefore, according to the present invention, it is possible to prevent the excessive temperature rise of the heating element in the non-sheet passing area while improving the fixing property of the small size paper without increasing the size of the apparatus and fixing failure. An object of the present invention is to provide a fixing device that can be used and an image forming apparatus including the fixing device.

[0015]

According to the present application, the above object is to provide a heating body for heating a recording material carrying an unfixed image by supplying electric power from a power source, and an endless belt-shaped member sliding on the heating body. The rotatable film member and a rotatable pressurizing body which is pressed against the heating body through the film member, and the recording is performed at a nip formed by pressing the pressing body against the heating body. A fixing device for sandwiching and transporting a material between the film member and the pressure body to heat and pressurize the unfixed image to the recording material, and detecting the temperature of the heating body in the paper passing area of the nip. In a fixing device including a temperature detection unit and a control unit that controls power supply from a power source to a heating body such that the sheet passing region temperature detected by the temperature detection unit reaches a set temperature of a predetermined temperature at which fixing is possible, Material The recording means identifying means for identifying the width dimension in the direction perpendicular to the transport direction is provided, and the control means, when the width dimension identified by the recording material identifying means is equal to or less than a predetermined length, the control means determines the width dimension. Is achieved by the first invention of having a set temperature lowering mode that is set lower than when the is longer than a predetermined length.

According to the present application, in the first aspect of the present invention, the recording material identifying means has an input means for selecting and inputting a width dimension of the recording material from the outside. It is also achieved by the second invention in which the width dimension of the recording material can be identified by the width dimension input to.

Further, according to the present application, in the first or second invention, the above-mentioned object is such that the recording material identifying means is arranged at a predetermined position of the recording material conveying path in a direction perpendicular to the conveying direction of the recording material. With recording material detection means to detect the width dimension at
It is also achieved by the third invention that the width dimension of the recording material can be identified by the width dimension detected by the recording material detection means.

According to the present application, the above-mentioned object is the control means according to any one of the first to third inventions,
The present invention can also be achieved by the fourth invention in which the setting temperature lowering mode is always selected when the width dimension identified by the recording material identifying means is equal to or less than the predetermined length.

Further, according to the present invention, in the above object, in any one of the first invention to the fourth invention, the control means has the width dimension identified by the recording material identification means is not more than a predetermined length. At this time, it is also achieved by the fifth invention in which the low temperature mode is set in accordance with the operating environment of the fixing device.

Further, according to the present invention, the above object is to provide a non-sheet passing area temperature detecting means for detecting the temperature of the non-sheet passing area of the heating body in any one of the first invention to the fifth invention. Then
It is also achieved by the sixth invention that the control means is set to select the set temperature lowering mode when the temperature detected by the non-sheet passing area temperature detecting means is equal to or higher than a predetermined temperature.

Further, according to the present application, the above-mentioned object is set in any one of the first invention to the sixth invention such that the control means selects the set temperature lowering mode during the continuous fixing processing a predetermined number of times or more. It is also achieved by the seventh invention that has been done.

Further, according to the present application, the above-mentioned object is the control means according to any one of the first to seventh inventions,
It is also achieved by the eighth invention that the set temperature lowering mode is set to be selected after a predetermined number of times in the continuous fixing process.

Further, according to the present application, in the above-mentioned object, in any one of the first to eighth inventions, the recording material identifying means can identify the length of the recording material in the conveying direction,
It is also achieved by the ninth invention that the control means is set so as to select the set temperature lowering mode when the length is equal to or longer than the predetermined length.

Further, according to the present application, in any one of the first to ninth inventions, the above-mentioned object is that the recording material identification means can identify the thickness of the recording material, and the control means is ,
The present invention is also achieved by a tenth aspect of the invention in which the set temperature lowering mode is set to be selected when the thickness is equal to or larger than a predetermined thickness.

Further, according to the present application, in the above-mentioned object, in any one of the first to tenth inventions, the control means is such that the temperature detected by the temperature detection means at the time of starting the fixing device is equal to or higher than a predetermined temperature. The present invention is also achieved by the eleventh invention in which the setting temperature lowering mode is set to be selected.

Further, according to the present application, the above object is to provide, in any one of the first to eleventh inventions, another temperature detecting means for detecting a temperature at a predetermined position of the fixing device. The present invention can also be achieved by the twelfth invention in which the set temperature lowering mode is set to be selected when the temperature detected by the other temperature detecting means is equal to or higher than the predetermined temperature.

Further, according to the present application, in any one of the first to twelfth aspects of the present invention, the control means has a predetermined fixing device corresponding to the temperature detected by the temperature detection means. The present invention is also achieved by a thirteenth invention, which is capable of detecting the temperature at a position and is set to select the set temperature lowering mode when the temperature is equal to or higher than a predetermined temperature.

According to the present application, the above object is an image forming apparatus for recording an image formed by a series of image forming processes on a recording medium, and the image forming apparatus includes the fixing device of the first invention. It is also achieved by the fourth invention.

Further, according to the present application, in the fourteenth aspect of the present invention, the recording material identifying means has an input means for selecting and inputting a width dimension of the recording material from the outside. It is also achieved by the fifteenth invention that the width dimension of the recording material can be identified by the width dimension input to the means.

Further, according to the present application, in the fourteenth aspect of the invention or the fifteenth aspect of the invention, the recording material identifying means is
A recording material detection unit that detects a width dimension of the recording material in a direction perpendicular to the conveyance direction is provided at a predetermined position of the recording material conveyance path, and the recording material width dimension is determined by the width dimension detected by the recording material detection unit. It is also achieved by the sixteenth invention that can identify.

Further, according to the present application, in the above object, in any one of the fourteenth invention to the sixteenth invention, the control means is such that the width dimension identified by the recording material identification means is equal to or less than a predetermined length. It is also achieved by the seventeenth invention in which the setting temperature lowering mode is always selected.

Further, according to the present application, in any one of the fourteenth invention to the seventeenth invention, the control means is such that the width dimension identified by the recording material identification means is equal to or less than a predetermined length. It is also achieved by the eighteenth invention in which the low temperature mode is set in accordance with the operating environment of the fixing device.

Further, according to the present application, in any of the fourteenth invention to the eighteenth invention, the above-mentioned object is a non-sheet passing area temperature detecting means for detecting the temperature of the non-sheet passing area of the heating element. And the control means is set to select the set temperature lowering mode when the temperature detected by the non-sheet passing area temperature detecting means is equal to or higher than a predetermined temperature. It

Further, according to the present application, in any one of the fourteenth invention to the nineteenth invention, the control means selects the set temperature lowering mode during a continuous fixing process a predetermined number of times or more. It is also achieved by the twentieth invention that is set as follows.

Further, according to the present invention, in any one of the fourteenth invention to the twentieth invention, the control means selects the set temperature lowering mode after a predetermined number of times during the continuous fixing process. It is also achieved by the twenty-first invention that is set to do.

Further, according to the present invention, in the above object, in any one of the fourteenth invention to the twenty-first invention, the recording material identifying means can identify the length in the conveying direction of the recording material. It is also achieved by the twenty-second invention that the control means is set to select the set temperature lowering mode when the length is equal to or greater than the predetermined length.

Further, according to the present application, in the above object, in any one of the fourteenth invention to the twenty-second invention, the recording material identifying means can identify the thickness of the recording material. The control means is also achieved by the twenty-third invention in which the control means is set to select the set temperature lowering mode when the thickness is equal to or greater than the predetermined thickness.

Further, according to the present invention, in the above object, in any one of the fourteenth invention to the twenty-third invention, the control means is such that the temperature detected by the temperature detecting means at the time of starting the fixing device is It is also achieved by the twenty-fourth invention that the set temperature lowering mode is set to be selected when the temperature is equal to or higher than the predetermined temperature.

Further, according to the present application, the above object is to provide, in any of the fourteenth invention to the twenty-fourth invention, another temperature detecting means for detecting the temperature at a predetermined position of the fixing device. The present invention can also be achieved by the twenty-fifth invention in which the set temperature lowering mode is selected when the temperature detected by the other temperature detecting means is equal to or higher than a predetermined temperature.

According to the present application, the above-mentioned object is the fixing device according to any one of the fourteenth invention to the twenty-fifth invention, in which the control means corresponds to the temperature detected by the temperature detection means. It is also achieved by the twenty-sixth invention that the temperature at the predetermined position can be detected, and the set temperature lowering mode is selected when the temperature is equal to or higher than the predetermined temperature.

[0041]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) First, a first embodiment of the present invention will be described.

FIG. 1 is a schematic sectional view showing a schematic configuration of a digital copying machine (hereinafter referred to as a copying machine) which is an example of the image forming apparatus according to the present embodiment.

In the copying machine according to the present embodiment, as shown in FIG. 1, the original 19 is placed on the original table glass 20 fixedly arranged in the main body of the copying machine, and the required copying conditions are satisfied. After the setting, the copy start key (not shown) is pressed to rotate the photosensitive drum 39, which is the image carrier, in the clockwise direction indicated by the arrow at a predetermined peripheral speed, and to perform the image forming operation described later. Is started.

First, the light source 21, together with the reflection shade 22 and the first mirror 23, moves from the home position on the left side in the drawing to the right side in the drawing at a predetermined speed V along the lower surface of the document table glass 20. By moving the second mirror 24 and the third mirror 25 in the same direction at a speed of V / 2, the original table glass 20
The downward image surface of the document 19 placed on the upper side is illuminated and scanned from the left side to the right side. Then, the reflected light on the original surface of the illumination scanning light enters the CCD 50 through the fixed fourth mirror 26 and the imaging lens 29.

The CCD 50 outputs digitally converted data in accordance with the input light quantity, the laser light is emitted from the laser 27 in accordance with the data, and the surface of the photosensitive drum 39 is exposed through the fixed mirror 28.

Next, before the exposure, the surface of the photosensitive drum 39 which has been uniformly charged to a predetermined positive or negative potential by the primary charger 30 has a pattern corresponding to the original image formed by the exposure. An electrostatic latent image is sequentially formed, and the electrostatic latent image is conveyed to a portion facing the developing roller 32 of the developing device 31 as the photosensitive drum 39 rotates in the arrow direction.

Then, the developing roller 32 which rotates while carrying the toner (not shown) contained in the developing device 31.
And a predetermined developing bias is applied from the developing bias power source 32A between the photosensitive drum 39 and the photosensitive drum 39,
The toner on the developing roller 32 is transferred to the electrostatic latent image on the photosensitive drum 39, and the electrostatic latent image is visualized as a toner image.

On the other hand, the recording material P is fed by the paper feed roller 51 in synchronism with the above-described image development process, and the recording material P passes through the guide 33 and functions as the photosensitive drum 39 and the transfer device at a predetermined timing. It is introduced into the transfer section between the transfer roller 34 and the transfer roller 34.

The recording material P is brought into contact with the photosensitive drum 39 at the transfer portion and receives the transfer corona, whereby the toner images on the surface of the photosensitive drum 39 are sequentially transferred to the upper surface of the recording material P.

Next, the recording material P that has passed through this transfer portion is
The charge removal needle 35 removes the charge on the back surface and sequentially separates the charge from the surface of the photosensitive drum 39.

After that, the recording material P is introduced into the fixing device 60 via the conveying belt 38 and the entrance guide 10, the toner image is fixed as described later, and the recording material P is ejected to the outside of the apparatus as an image formed product.

On the other hand, the surface of the photosensitive drum 39 after transfer is
The cleaning blade 37 of the cleaning member 36 cleans and removes stains such as residual toner, and is repeatedly used for image formation.

Further, the moving optical members 21 to 25, which have moved on the outward path as described above, are set so as to move on the return path when reaching a predetermined outward path end point, and return to the initial home position and then the next copy. Wait until the start of the cycle.

Next, the fixing device 60 provided in the copying machine according to this embodiment will be described with reference to FIG.

As shown in FIG. 2, the fixing device 60 includes an endless belt-shaped fixing film 6 as a film member.
The fixing film 6 includes a driving roller 7 on the left side in the drawing, a driven roller 8 on the right side in the drawing, and a heating member fixedly arranged below the driving roller 7 and the driven roller 8. It is stretched by a low heat capacity linear heater 1.

This endless belt-shaped fixing film 6
Is repeatedly used for heat-fixing a toner image, so that it has excellent heat resistance, releasability and durability, and the thickness is generally 100 μm or less, preferably 40 μm or less. It

As an example, a highly heat-resistant resin such as polyimide, polyetherimide, polyethersulfone, or polyetheretherketone having a thickness of 20 μm or nickel,
PTF is applied to the outer peripheral surface of a thin metal endless belt such as SUS
Low surface energy resin such as E (tetrafluoroethylene resin), PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin), or a release coating layer in which a conductive material such as carbon black is added to these resins 1
An endless belt-shaped fixing film having a layer thickness of 30 μm applied to a thickness of 0 μm can be used.

Further, the heater 1 having a low heat capacity as a heating body which constitutes the heating means together with the fixing film 6 has a thickness of 1.0 mm, a width of 10 mm and a longitudinal length of 340 m.
A resistive material such as silver palladium or ruthenium oxide having a thickness of 10 μm and a width of 1.0 mm is applied to an alumina substrate 2 having a thickness of 10 m to form a heat generating layer 3, and a fixing film 6 having a thickness of 10 μm is formed thereon. The protective layer 4 made of glass or the like in consideration of sliding is formed, and is fixedly supported by being attached and held to the heater support 11.

The heater support 11 has a heat insulating property, a high heat resistance, and rigidity for adiabatically supporting the fixing device 60 of the heater 1 and the copying machine. For example, PPS (polyphenylene sulfide) or PEEK (polyether ether). (Ketone), a liquid crystal polymer, or other high heat resistant resin, or a composite material of these resins and ceramics or metal.

The heating layer 3 of the heater 1 is supplied with AC power of 100 V from both ends in the longitudinal direction by a fixing power source 1A which is a power source, and is bonded or pressure-bonded to or integrated with the back surface of the substrate 2 by a heat conductive silicone rubber adhesive or the like. The power supply from the fixing power supply 1A is controlled by the control means (not shown) according to the temperature detected by the thermistor 5, which is the temperature detection means formed in the above.

Further, the driven roller 8 also serves as a tension roller for applying tension in the direction in which the fixing film 6 is stretched outward, and the fixing film 6 has a surface coated with silicone rubber or the like to increase the friction coefficient. Along with the clockwise rotational driving of 7, the driving is performed in the clockwise direction at a predetermined peripheral speed without wrinkles, meandering, or speed delay.

The surface of the fixing device 60 is an insulating layer,
For example, a pressurizing body having a longitudinal direction of 380 mm and a diameter of 25 mm, which is covered with an insulating tube 9a made of fluororesin such as PFA or the like having excellent release properties and durability and whose inside is made of a conductive rubber layer 9b as a conductive member. The pressure roller 9 is provided. The pressure roller 9 sandwiches the endless belt-shaped lower film portion of the fixing film 6 with the heater 1,
The lower surface of the heater 1 is pressed against the lower surface of the heater 1 by a biasing means such as a spring with an abutting force of 49 to 98 N (5 to 10 kgf) so that the recording material P is rotated counterclockwise in the forward direction. Has become.

In the fixing device 60 having the above-described structure, the recording material P as a recording material on which the unfixed toner image T as a developer image is transferred to the upper surface is guided to the guide 10 by the image forming operation as described above. And the pressure contact portion between the heater 1 and the pressure roller 9 formed via the fixing film 6 (hereinafter,
When it enters the fixing nip portion N, the unfixed toner image T comes into close contact with the lower surface of the fixing film 6 and causes surface deviation, wrinkles, and
It passes through the fixing nip portion N while receiving a pinching pressure in the overlapping state with the fixing film 6 without causing a deviation.

At this time, the toner image bearing surface of the recording material P is
The fixing nip portion N is pressed and fixed on the surface of the fixing film 6.
In the process of passing through, the heat of the heat generating layer 3 is received through the fixing film 6, and the toner image T is melted at a high temperature and softened on the surface of the recording material P to become a toner image Ta that is adhered.

Further, the recording material P passing through the fixing nip portion N
Is cooled while being guided by the guide 12, and the toner image Ta that has been softened and adhered becomes a fixed image Tb fixed to the toner image carrying surface of the recording material P.

Next, the heater 1 in the fixing device 60
The temperature on the back side of the heating element is shown in FIGS. 3 and 4.

FIG. 3 shows the temperature Temp1 of the central portion of the temperature on the backside of the heating element of the heater 1 when A3 paper is continuously passed through the fixing nip portion N as large-sized paper and the paper passing for large-sized paper. The result of having measured the temperature Temp2 of the edge part which becomes a range with a thermocouple is shown.

In the present embodiment, the above-mentioned control means responds to the temperature detected by the thermistor 5 so that the heater 1 is normally controlled to 190 ° C. when the large-size paper is passed through the fixing nip portion N. The electric power supply from the fixing power source 1A to the heater 1 is controlled.

As shown in FIG. 3, when large size paper is passed, the temperature Templ at the center and the temperature Temp2 at the end of the heater 1 are such that the temperature Temp2 at the end is slightly lower than the temperature Temp1. there were. This is because the heat fixing device 6
This is because the temperature at the end became a little low because it escaped from the end of 0.

In general, in the case of passing large-sized paper, the fixing property is such that the edge part is less apt to wick than the central part. Therefore, the fixing temperature is finally set by searching for a fixing temperature condition that makes the fixing property of the end portion practically practical.

FIG. 4 shows the temperature on the backside of the heating element of the heater 1 when A4 paper having a small size is vertically passed through the fixing nip portion N continuously. In addition, the temperature Temp3 of the central portion and the temperature Temp4 of the end portion which becomes the sheet passing area in the case of a small size are measured by a thermocouple.

The heater 1 is controlled at 190 ° C.,
Similar to FIG. 3, the energization of the heater 1 is controlled according to the temperature detected by the thermistor 5, but since the thermistor 5 in the central portion is controlled to 190 ° C., the non-sheet passing portion at the end is controlled. The temperature Temp4 is the temperature Temp of the sheet passing portion at the center.
It is higher than 3 because the temperature of the non-sheet-passing portion rises, and the number of passing sheets increases.

FIGS. 5 and 6 show large size paper (A3 portrait).
And the heater 1, the fixing film 6, the pressure roller in the longitudinal direction perpendicular to the paper conveyance of the fixing device 60 when a large number of small size papers (A4 vertical) are continuously passed through the fixing nip portion N. 9 shows the temperature distribution of No. 9. In this case, the temperatures of the heater 1 and the pressure roller 9 were measured with a thermocouple, but the surface temperature of the fixing film 6 was measured with a non-contact thermometer (thermopure) or the like because the heat capacity of the fixing film 6 is small.

FIG. 5 shows a case where a large number of large size sheets are passed through the fixing nip portion N. In this case, the temperature distribution in the longitudinal direction of the fixing device 60 is basically constant, although the temperature slightly decreases at the end.

Next, in FIG. 6, the small size paper is fixed to the fixing nip portion N.
The case where a large number of sheets are passed is shown in.

As shown in FIG. 6, the temperature distribution in the longitudinal direction of the fixing device 60 is extremely high in the non-sheet passing portion of small size paper, and so-called non-sheet passing portion temperature rise occurs.
Also, when the temperature rise in the non-sheet passing area occurs, the heat is partly circulated into the paper passing area of small size paper, and as a result, during continuous small size paper passing, the temperature distribution in the longitudinal direction of the fixing device becomes Occurs that the central part has the lowest temperature.

Therefore, in FIG. 6, the fixability in the case where the temperature rise of the non-sheet passing portion occurs during the continuous feeding of the small size sheet to the fixing nip portion N is the same fixing temperature, large size sheet passing. It has the following differences compared to.

The fixing property of the large size is the worst at the end.

The fixing property of the large-sized central portion is good, and is the same as that of the small-sized central portion.

The fixing property of the small size end portion is better than that of the small size center portion.

These are the case where the temperature distribution in the longitudinal direction of the fixing device 60 is the case where the large size paper passes through the fixing nip portion N (hereinafter referred to as the large size paper) and the small size paper passes through the fixing nip portion N. This is because the temperature distribution at the central portion and that at the end portion are reversed in the case of passing the sheet (hereinafter referred to as large-sized sheet).

Therefore, in the case of small-size sheet passing, the fixing temperature control temperature can be lowered as compared with the case of large-size sheet passing.

Further, the temperature rise in the non-sheet passing portion occurs during the sheet passing even in the case of one sheet small size sheet passing, so that the fixing device 6 starts from the first sheet.
It is also possible to reduce the temperature to zero.

In the present embodiment, first, the user selects the paper type and inputs the paper type from the display panel (not shown) which is an input means. Based on the information, it is determined whether the recording material identification means (not shown) is a small size or a large size.

Then, the fixing temperature control temperature was determined as shown in Table 1.

[0087]

[Table 1]

As shown in Table 1, the temperature control of the fixing device 60 at the time of passing a large size sheet is set to 190 ° C., and the fixing temperature control at the time of passing a small size sheet is set to 180 ° C. as a small size temperature control lowering control which is a set temperature lowering mode. And Even if the temperature control of small size paper is lower than the temperature control of large size paper in this way, the fixability is practically no problem, and the temperature rise in the non-sheet passing area that occurs during small size paper passing. It was possible to lower the temperature by about 10 ° C.

(Second Embodiment) Next, a second embodiment of the present invention will be described. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

Table 2 shows the fixing temperature control temperature control for each number of sheets passed through the fixing device (the number of times the sheet is passed through the fixing nip portion N) during the passage of the large size sheet and the passage of the small size sheet according to the second embodiment of the present invention. It is a table showing.

[0091]

[Table 2]

That is, the temperature control during the passage of large-sized sheets is 200 ° C. when the fixing device 60 is cold, and is lowered to 195 ° C., 190 ° C., and 185 ° C. as the number of sheets advances. For small size paper, the temperature is 10 ℃ lower and 190 ℃ when the fixing device 60 is cold.
This is the case when the temperature is lowered to 180 ° C., 175 ° C. This embodiment is effective when the temperature rise of the pressure roller 9 is slower than the temperature rise of the heater 1.

(Third Embodiment) Next, a third embodiment of the present invention will be described. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the present embodiment, the above-mentioned recording material identification means is provided in the main body of the digital copying machine for discriminating between the large-sized paper and the small-sized paper, instead of the user selecting the paper type on the display panel. It is automatically determined by the width dimension detected by a paper width detection sensor (not shown) which is a recording material detection means. That is, the above-mentioned paper width detection sensor is provided in a paper conveying section, a paper feeding section, a cassette or the like to automatically detect the width in the longitudinal direction of the paper. In this case, the operation by the user or the like becomes unnecessary, and it is effective in case of an erroneous setting.

The temperature control of the fixing device when it is determined that the paper is small size is performed in the same manner as in the first and second embodiments.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

Table 3 is a table showing fixing temperature control temperature control for each number of sheets passed through the fixing device during large-size sheet passing and small-size sheet passing in the fourth embodiment of the present invention.

[0098]

[Table 3]

That is, a case is shown in which the small size temperature control decrease control is performed by the number of passed sheets.

Even in the case of passing small-sized paper, the temperature at the initial stage of the non-paper-passage temperature rise, that is, the first sheet of paper, is more advantageous in temperature than large-sized paper, but less advantageous. Therefore, the temperature control temperature is set to be the same as that of the large size paper in the initial stage of continuous paper feeding, for example, up to 10 sheets. Then, after the temperature of the non-sheet passing portion rises, the heat begins to circulate in the small size sheet passing area and a margin for fixing property is generated. For example, after the 11th sheet, the fixing temperature control of the small size sheet is adjusted to that of the large size sheet. The temperature is lowered from the fixing temperature control.

(Fifth Embodiment) Next, a fifth embodiment of the present invention will be described. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

Table 4 is a table showing the fixing temperature control temperature control for each number of sheets passed through the fixing device at the time of passing a large size sheet and a small size sheet according to the fifth embodiment of the present invention.

[0103]

[Table 4]

That is, another embodiment is shown in which the small size temperature control decrease control is performed by the number of passed sheets, which is a development system of the fourth embodiment.

In the fifth embodiment, as can be seen from Table 5, the small size temperature control decrease control is not performed for the first to tenth sheets, but is performed for the eleventh and subsequent sheets. The value of the temperature decrease is set to a larger value after the 50th sheet and the 100th sheet, where the temperature increase of the non-sheet passing portion is expected to be large.

The fixing property of the small size paper is improved because the heat is circulated as the temperature rise of the non-sheet passing portion is increased. Therefore, it is possible to further lower the fixing temperature control, and therefore, the effect of lowering the temperature rise of the non-sheet passing portion is increased.

The control of this embodiment is particularly effective when a large number of small sizes are continuously passed.

(Sixth Embodiment) Next, a sixth embodiment of the present invention will be described. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

Table 5 shows the fixing temperature control temperature for each number of copies installed (the number of continuous paper feeds set at the start of copying) at the time of large-size paper passing and small-size paper passing in the sixth embodiment of the present invention. It is a table which shows control.

[0110]

[Table 5]

That is, the case where the small size temperature control decrease control is performed by the number of copies installed by the user is shown.

In the case of continuous paper feeding, for example, for copying up to 10 sheets, the temperature control temperature is set to be the same as that of large size paper.
When the user sets a larger number than that, the fixing temperature control of the small size paper is made lower than that of the large size paper from the first school. In this case,
There is an advantage that the control becomes simpler than that of the fifth embodiment.

(Seventh Embodiment) Next, a seventh embodiment of the present invention will be described. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

Table 6 is a table showing the fixing temperature control temperature control for each number of sheets passed through the fixing device when a large size sheet of each size is passed and a small size sheet is passed in the seventh embodiment of the present invention.

[0115]

[Table 6]

That is, a case is shown in which the small-size temperature control decrease control is changed depending on the small-sized recording material to be passed.

For example, in the fixing device 60 having a large size of A3 paper (vertical) or A4 (horizontal), A4 (vertical) and A5
When passing (horizontal) paper, it is treated as a small size. However, when 10 sheets of A4 (vertical) sheet are passed,
When the A5 (horizontal) 10 sheets are passed, the temperature rise in the non-sheet passing portion is different.

Therefore, the margin of fixing property is different, and therefore the lowering temperature of the small size temperature control lowering control is also different. An embodiment incorporating this is shown. That is, the small size temperature control is performed by the number of sheets converted into the length. The same effect can be obtained by simply changing the temperature.

(Eighth Embodiment) Next, an eighth embodiment of the present invention will be described. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

Table 7 is a table showing the fixing temperature control temperature control for each number of sheets passed through the fixing device when a large size sheet of each thickness is passed and a small size sheet is passed in the eighth embodiment of the present invention.

Table 7 is an eighth embodiment of the present invention.

[0122]

[Table 7]

That is, the case is shown in which the small size temperature control decrease control is also performed depending on the paper thickness. In Table 7, even if the size is small, the tracing control of the small size is not performed on the tracing paper, but is performed on the plain paper, the thick paper, and the postcard. The degree of temperature decrease is small for plain paper and large for thick paper and postcards. In this example, the effect of lowering the temperature rise of the non-sheet passing portion can be obtained.

(Ninth Embodiment) Next, a ninth embodiment of the present invention will be described. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

FIG. 7 is a sectional view showing the schematic arrangement of a fixing device according to the ninth embodiment of the present invention.

That is, in addition to the thermistor 5 for detecting the temperature of the fixing device 60, the temperature from the second temperature detecting element 5A, which is another temperature detecting means installed in any of the fixing devices, is also detected, and the small size temperature is detected. The figure shows the case where the adjustment control is performed. As shown in FIG. 7, the temperature of the pressure roller 9 in the small-size sheet passing area is detected by the second temperature detecting element 5A.

Even if the second temperature detecting element 5A is inside the small-sized paper sheet, if it is known that the small-sized paper sheet is being passed, the number of sheets passed and the second temperature detecting element 5A. From the detected temperature, it is possible to estimate the temperature of the non-sheet-passage temperature rise. For example, when a small-sized sheet is selected by the user and the temperature of the second temperature detecting element 5A is equal to or higher than the specified temperature, it is determined that the temperature of the non-sheet passing portion has risen and the temperature corresponding to the specified temperature is exceeded. It has been depressed. This is shown in Table 8.

[0128]

[Table 8]

Although the second temperature detecting element 5A is installed in the small size paper passing area in this embodiment, it may be installed in the non-paper passing area.

(Tenth Embodiment) Next, a tenth embodiment of the present invention will be described. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, not the actual temperature from the second temperature detecting element installed in the fixing device in the ninth embodiment but the temperature of a certain portion of the fixing device 60 is estimated, and the estimated temperature is used. , Shows the case where the small size temperature control decrease control is performed. Specifically, the temperature at the center of the pressure roller 9 is estimated, and the small size temperature control decrease control is performed based on the estimated temperature.

The estimated temperature of the pressure roller 9 is determined by the following procedure.

First, when a copy signal is issued, the temperature Tl of the thermistor 5 for adjusting the temperature of the fixing device is read.
Since this Tl is read before the operation of the fixing device 60,
It is considered that the temperature of the fixing device 60 is generally uniform and the temperature of the heater 1 is almost equal to the temperature of the pressure roller 9.

Next, when the copying operation is performed, the estimated temperature TS of the pressure roller 9 becomes as follows.

TS = T1 + 50 + 3 × N N is the number of sheets that have passed through the fixing device 60 after the copying operation is performed. However, it is reset at the end of the copying operation. The estimated temperature TS of the pressure roller 9 is 25 + 50 + 3 × 10 = 105.
℃.

This estimated temperature has an upper limit of 150 ° C.
No more is added.

In this case, if it is known that the sheet is of small size, it is possible to estimate the non-sheet-passage temperature from the number of sheets passed and the estimated temperature TS of the pressure roller 9.
For example, when the user selects small-sized sheet passing and the estimated temperature TS of the pressure roller 9 is equal to or higher than the specified temperature, it is determined that the non-sheet passing portion temperature rise has occurred and the temperature corresponding to the specified temperature is reached. It has been depressed. This is shown in Table 9.

[0138]

[Table 9]

The difference between the ninth embodiment and the tenth embodiment is
Regarding the temperature detection of the pressure roller 9, it depends on whether the actual temperature is measured or estimated.

The tenth embodiment has an advantage that the second temperature detecting element is unnecessary.

These embodiments may be carried out alone or in combination. Further, the small size temperature control decrease control may be performed by a plurality of controls other than the large size and the small size, such as a medium size. In any case, it was possible to suppress the temperature rise in the non-sheet passing portion without deteriorating the fixability of the small size.

(Eleventh Embodiment) Next, an eleventh embodiment of the present invention will be described. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

FIG. 8 is a sectional view showing the schematic arrangement of a fixing device according to the eleventh embodiment of the present invention.

That is, this is a case where the film driving of the fixing device is performed not by the driving roller 7 but by the pressure roller 9. In this case, the fixing film 6 is preferably thick to some extent. Even in this case, the same effect was obtained by the same method.

[0145]

As described above, according to the first invention of the present application, when the width dimension identified by the recording material identifying means is the predetermined length or less, the length is the predetermined length. Since it has a set temperature lowering mode in which the set temperature of the heating element is set lower than in the above case, it is possible to improve the fixability of small size paper without increasing the size of the device and fixing failure. At the same time, it is possible to prevent excessive temperature rise in the non-sheet passing area of the heating element.

According to the second invention of the present application,
When the width dimension identified by the recording material identification means is less than or equal to the predetermined length, the set temperature of the heating element is set lower than when the length is greater than or equal to the predetermined length. Therefore, it is possible to prevent the excessive temperature rise in the non-sheet passing area of the heating body while improving the fixability of the small size paper without increasing the size of the apparatus or causing the fixing failure.

Further, according to the third invention of the present application, when the width dimension identified by the recording material identifying means is not more than the predetermined length, it is more than when the length is not less than the predetermined length. Since it has a set temperature lowering mode in which the set temperature of the heating element is set low, without increasing the size of the device or fixing failure, while improving the fixability of small size paper,
It is possible to prevent excessive temperature rise in the non-sheet passing area of the heating element.

According to the fourth invention of the present application,
When the width dimension identified by the recording material identification means is less than or equal to the predetermined length, the set temperature of the heating element is set lower than when the length is greater than or equal to the predetermined length. Therefore, it is possible to prevent the excessive temperature rise in the non-sheet passing area of the heating body while improving the fixability of the small size paper without increasing the size of the apparatus or causing the fixing failure.

Further, according to the fifth invention of the present application, when the width dimension identified by the recording material identifying means is equal to or less than the predetermined length, the length is greater than or equal to the predetermined length. Since it has a set temperature lowering mode in which the set temperature of the heating element is set low, without increasing the size of the device or fixing failure, while improving the fixability of small size paper,
It is possible to prevent excessive temperature rise in the non-sheet passing area of the heating element.

According to the sixth invention of the present application,
When the width dimension identified by the recording material identification means is less than or equal to the predetermined length, the set temperature of the heating element is set lower than when the length is greater than or equal to the predetermined length. Therefore, it is possible to prevent the excessive temperature rise in the non-sheet passing area of the heating body while improving the fixability of the small size paper without increasing the size of the apparatus or causing the fixing failure.

Further, according to the seventh invention of the present application, when the width dimension identified by the recording material identification means is equal to or less than the predetermined length, the length is greater than or equal to the predetermined length. Since it has a set temperature lowering mode in which the set temperature of the heating element is set low, without increasing the size of the device or fixing failure, while improving the fixability of small size paper,
It is possible to prevent excessive temperature rise in the non-sheet passing area of the heating element.

According to the eighth invention of the present application,
When the width dimension identified by the recording material identification means is less than or equal to the predetermined length, the set temperature of the heating element is set lower than when the length is greater than or equal to the predetermined length. Therefore, it is possible to prevent the excessive temperature rise in the non-sheet passing area of the heating body while improving the fixability of the small size paper without increasing the size of the apparatus or causing the fixing failure.

Further, according to the ninth invention of the present application, when the width dimension identified by the recording material identifying means is less than or equal to the predetermined length, the length is greater than or equal to the predetermined length. Since it has a set temperature lowering mode in which the set temperature of the heating element is set low, without increasing the size of the device or fixing failure, while improving the fixability of small size paper,
It is possible to prevent excessive temperature rise in the non-sheet passing area of the heating element.

According to the tenth invention of the present application,
When the width dimension identified by the recording material identification means is less than or equal to the predetermined length, the set temperature of the heating element is set lower than when the length is greater than or equal to the predetermined length. Therefore, it is possible to prevent the excessive temperature rise in the non-sheet passing area of the heating body while improving the fixability of the small size paper without increasing the size of the apparatus or causing the fixing failure.

Further, according to the eleventh invention of the present application, when the width dimension identified by the recording material identifying means is equal to or less than the predetermined length, the length is greater than or equal to the predetermined length. Since it also has a set temperature lowering mode in which the set temperature of the heating element is set low, without increasing the size of the device and fixing failure, while improving the fixability of small size paper,
It is possible to prevent excessive temperature rise in the non-sheet passing area of the heating element.

According to the twelfth invention of the present application, when the width dimension identified by the recording material identifying means is equal to or less than a predetermined length, the length is greater than or equal to the predetermined length. Since it also has a set temperature lowering mode in which the set temperature of the heating element is set low, without increasing the size of the device and fixing failure, while improving the fixability of small size paper,
It is possible to prevent excessive temperature rise in the non-sheet passing area of the heating element.

Further, according to the thirteenth invention of the present application, when the width dimension identified by the recording material identifying means is equal to or less than the predetermined length, the length is greater than or equal to the predetermined length. Since it also has a set temperature lowering mode in which the set temperature of the heating element is set low, without increasing the size of the device and fixing failure, while improving the fixability of small size paper,
It is possible to prevent excessive temperature rise in the non-sheet passing area of the heating element.

According to the fourteenth invention of the present application, when the width dimension identified by the recording material identifying means is equal to or less than the predetermined length, the length is greater than or equal to the predetermined length. Since it also has a set temperature lowering mode in which the set temperature of the heating element is set low, without increasing the size of the device and fixing failure, while improving the fixability of small size paper,
It is possible to prevent excessive temperature rise in the non-sheet passing area of the heating element.

Further, according to the fifteenth invention of the present application, when the width dimension identified by the recording material identifying means is equal to or less than the predetermined length, the length is greater than or equal to the predetermined length. Since it also has a set temperature lowering mode in which the set temperature of the heating element is set low, without increasing the size of the device and fixing failure, while improving the fixability of small size paper,
It is possible to prevent excessive temperature rise in the non-sheet passing area of the heating element.

According to the sixteenth invention of the present application, when the width dimension identified by the recording material identifying means is equal to or less than the predetermined length, the width dimension is greater than or equal to the predetermined length. Since it also has a set temperature lowering mode in which the set temperature of the heating element is set low, without increasing the size of the device and fixing failure, while improving the fixability of small size paper,
It is possible to prevent excessive temperature rise in the non-sheet passing area of the heating element.

Further, according to the seventeenth invention of the present application, when the width dimension identified by the recording material identification means is equal to or less than the predetermined length, the length is greater than or equal to the predetermined length. Since it also has a set temperature lowering mode in which the set temperature of the heating element is set low, without increasing the size of the device and fixing failure, while improving the fixability of small size paper,
It is possible to prevent excessive temperature rise in the non-sheet passing area of the heating element.

Further, according to the eighteenth invention of the present application, when the width dimension identified by the recording material identifying means is equal to or less than the predetermined length, the length is greater than or equal to the predetermined length. Since it also has a set temperature lowering mode in which the set temperature of the heating element is set low, without increasing the size of the device and fixing failure, while improving the fixability of small size paper,
It is possible to prevent excessive temperature rise in the non-sheet passing area of the heating element.

Furthermore, according to the nineteenth invention of the present application, when the width dimension identified by the recording material identifying means is equal to or less than the predetermined length, the length is greater than or equal to the predetermined length. Since it also has a set temperature lowering mode in which the set temperature of the heating element is set low, without increasing the size of the device and fixing failure, while improving the fixability of small size paper,
It is possible to prevent excessive temperature rise in the non-sheet passing area of the heating element.

According to the twentieth invention of the present application, when the width dimension identified by the recording material identifying means is equal to or less than the predetermined length, the length is greater than or equal to the predetermined length. Since it also has a set temperature lowering mode in which the set temperature of the heating element is set low, without increasing the size of the device and fixing failure, while improving the fixability of small size paper,
It is possible to prevent excessive temperature rise in the non-sheet passing area of the heating element.

Further, according to the twenty-first invention of the present application, when the width dimension identified by the recording material identifying means is not more than the predetermined length, and when the length is not less than the predetermined length. Since it has a set temperature lowering mode in which the set temperature of the heating element is set lower than that of the heating element, it is possible to improve the fixability of small size paper without increasing the size of the device or defective fixing, It is possible to prevent excessive temperature rise in the paper non-passage area.

According to the twenty-second invention of the present application, when the width dimension identified by the recording material identifying means is not more than the predetermined length, and when the length is not less than the predetermined length. Since it has a set temperature lowering mode in which the set temperature of the heating element is set lower than that of the heating element, the fixing property of small size paper is improved without increasing the size of the device or defective fixing.
It is possible to prevent excessive temperature rise in the non-sheet passing area of the heating element.

Further, according to the twenty-third invention of the present application, when the width dimension identified by the recording material identifying means is equal to or less than the predetermined length, or when the length is equal to or more than the predetermined length. Since it has a set temperature lowering mode in which the set temperature of the heating element is set lower than that of the heating element, it is possible to improve the fixability of small size paper without increasing the size of the device or defective fixing, It is possible to prevent excessive temperature rise in the paper non-passage area.

According to the twenty-fourth invention of the present application, when the width dimension identified by the recording material identifying means is equal to or less than the predetermined length, and the length is equal to or more than the predetermined length. Since it has a set temperature lowering mode in which the set temperature of the heating element is set lower than that of the heating element, the fixing property of small size paper is improved without increasing the size of the device or defective fixing.
It is possible to prevent excessive temperature rise in the non-sheet passing area of the heating element.

Further, according to the twenty-fifth aspect of the present invention, when the width dimension identified by the recording material identifying means is equal to or less than the predetermined length, and when the length is equal to or more than the predetermined length. Since it has a set temperature lowering mode in which the set temperature of the heating element is set lower than that of the heating element, it is possible to improve the fixability of small size paper without increasing the size of the device or defective fixing, It is possible to prevent excessive temperature rise in the paper non-passage area.

According to the twenty-sixth invention of the present application, when the width dimension identified by the recording material identifying means is not more than the predetermined length, and when the length is not less than the predetermined length. Since it has a set temperature lowering mode in which the set temperature of the heating element is set lower than that of the heating element, the fixing property of small size paper is improved without increasing the size of the device or defective fixing.
It is possible to prevent excessive temperature rise in the non-sheet passing area of the heating element.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a schematic configuration of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a schematic configuration of a fixing device provided in the image forming apparatus of FIG.

FIG. 3 is a diagram showing a relationship between the number of times of nip passage of A3 sheets and temperatures of a sheet passing region and a non-sheet passing region of a heating body.

FIG. 4 is a diagram showing the relationship between the number of times of nip paper passing of A4 paper and the temperatures of a paper passing area and a non-paper passing area of a heating body.

FIG. 5 is a diagram showing a temperature distribution in the longitudinal direction (width direction of the recording material) of the heating body when the A3 paper is passed through the nip.

FIG. 6 is a diagram showing a temperature distribution in a longitudinal direction (width direction of a recording material) of a heating body when a nip of A4 paper is passed.

FIG. 7 is a schematic sectional view showing a schematic configuration of a fixing device according to a ninth embodiment of the present invention.

FIG. 8 is a schematic sectional view showing a schematic configuration of a fixing device according to an eleventh embodiment of the present invention.

[Explanation of symbols] 1 heater (heating body) 1A fixing power supply (power supply) 5 Thermistor (temperature detection means) 5A Second temperature detecting element (other temperature detecting means) 6 Fixing film (film member) 9 Pressure roller (Pressure body) 60 fixing device N fixing nip part (nip) P recording material (recording material) T toner image (unfixed image)

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H027 DA12 DA46 DC02 DC10 DE07                       DE10 EA12 EC02 EC06 ED25                       EE07 EF06 FA02 FA05 FA30                       FA35 FB07 FB19                 2H033 AA03 AA24 AA47 BA32 BA59                       BE03 CA04 CA05 CA07 CA16                       CA17 CA19 CA22 CA27

Claims (26)

[Claims] 1. A heating body for heating a recording material carrying an unfixed image by supplying electric power from a power source, an endless belt-like rotatable film member sliding on the heating body, and the interposition of the film member. A rotatable pressurizing body that is pressed against the heating body, and the recording material is nipped and conveyed by the film member and the pressing body at a nip formed by pressing the heating body against the heating body. A fixing device for fixing the unfixed image to the recording material while heating and pressurizing,
Temperature detecting means for detecting the temperature of the heating element in the paper passing area of the nip, and power supply from the power source to the heating element so that the temperature of the paper passing area detected by the temperature detecting means becomes a predetermined temperature at which fixing is possible. In the fixing device including the control means for controlling the recording material, the recording material identification means for identifying the width dimension of the recording material in the direction perpendicular to the conveying direction is provided, and the control means identifies the set temperature by the recording material identification means. A fixing device having a set temperature lowering mode in which when the width dimension is less than or equal to a predetermined length, it is set lower than when the width dimension is greater than or equal to the predetermined length. 2. The recording material identification means has an input means for selecting and inputting the width dimension of the recording material from the outside, and the width dimension of the recording material can be identified by the width dimension input to the input means. The fixing device according to claim 1, wherein the fixing device is provided. 3. The recording material identifying means has a recording material detecting means for detecting a width dimension in a direction perpendicular to the conveying direction of the recording material at a predetermined position of the conveying path of the recording material, and the recording material detecting means The fixing device according to claim 1 or 2, wherein the width dimension of the recording material can be identified by the detected width dimension. 4. The control means is set to always select the set temperature lowering mode when the width dimension identified by the recording material identification means is equal to or less than a predetermined length. Item 5. The fixing device according to any one of items 3. 5. The control means is set to select the low temperature mode according to the operating environment of the fixing device when the width dimension identified by the recording material identification means is equal to or less than a predetermined length. The fixing device according to any one of claims 1 to 4. 6. A non-paper passing area temperature detecting means for detecting a temperature of a non-paper passing area of the heating element, wherein the control means has a temperature detected by the non-paper passing area temperature detecting means is equal to or higher than a predetermined temperature. The fixing device according to any one of claims 1 to 5, wherein the fixing device is set to select the set temperature lowering mode. 7. The fixing device according to claim 1, wherein the control unit is set to select the set temperature lowering mode during continuous fixing processing a predetermined number of times or more. 8. The fixing device according to claim 1, wherein the control unit is set to select the set temperature lowering mode after a predetermined number of times during the continuous fixing process. . 9. The recording material identification means can also identify the length of the recording material in the conveying direction, and the control means selects the set temperature lowering mode when the length is equal to or more than a predetermined length. The fixing device according to claim 1, wherein the fixing device is set. 10. The recording material identification means can also identify the thickness of the recording material, and the control means is set to select the set temperature lowering mode when the thickness is equal to or greater than a predetermined thickness. The fixing device according to any one of claims 1 to 9. 11. The control means is set to select the set temperature lowering mode when the temperature detected by the temperature detecting means at the time of starting the fixing device is equal to or higher than a predetermined temperature. Item 10. The fixing device according to any one of items 10. 12. A fixing temperature lowering mode is selected when the temperature detecting means detects the temperature at a predetermined position of the fixing device and the temperature detected by the other temperature detecting means is equal to or higher than a predetermined temperature. The fixing device according to claim 1, wherein the fixing device is set as follows. 13. The control means can detect the temperature of a predetermined position of the fixing device in correspondence with the temperature detected by the temperature detection means, and selects the set temperature lowering mode when the temperature is equal to or higher than the predetermined temperature. The fixing device according to any one of claims 1 to 12, wherein the fixing device is set to perform. 14. An image forming apparatus for recording an image formed by a series of image forming processes on a recording medium, the image forming apparatus comprising the fixing device according to claim 1. 15. The recording material identification means has an input means for selecting and inputting the width dimension of the recording material from the outside, and the width dimension of the recording material can be identified by the width dimension input to the input means. The image forming apparatus according to claim 14, wherein the image forming apparatus is provided. 16. The recording material identifying means has a recording material detecting means for detecting a width dimension of the recording material in a direction perpendicular to the conveying direction of the recording material at a predetermined position of the conveying path of the recording material. The image forming apparatus according to claim 14 or 15, wherein the width dimension of the recording material can be identified by the detected width dimension. 17. The control means is set to always select the set temperature lowering mode when the width dimension identified by the recording material identification means is equal to or less than a predetermined length. Item 17. The image forming apparatus according to any one of items 16. 18. The control means is set to select the low temperature mode according to the operating environment of the fixing device when the width dimension identified by the recording material identifying means is equal to or less than a predetermined length. The image forming apparatus according to any one of claims 14 to 17. 19. A non-paper passing area temperature detecting means for detecting a temperature of a non-paper passing area of a heating body, wherein the control means has a temperature detected by the non-paper passing area temperature detecting means is equal to or higher than a predetermined temperature. The image forming apparatus according to any one of claims 14 to 18, wherein the image forming apparatus is set to select the set temperature lowering mode at that time. 20. The image forming apparatus according to claim 14, wherein the control unit is set so as to select the set temperature lowering mode during continuous fixing processing a predetermined number of times or more. . 21. The image forming apparatus according to claim 14, wherein the control unit is set to select the set temperature lowering mode after a predetermined number of times during the continuous fixing process. apparatus. 22. The recording material identification means can also identify the length of the recording material in the conveying direction, and the control means selects the set temperature lowering mode when the length is equal to or more than a predetermined length. It is assumed that it is set.
The image forming apparatus according to claim 1. 23. The recording material identification means can also identify the thickness of the recording material, and the control means is set to select the set temperature lowering mode when the thickness is equal to or more than a predetermined thickness. The image forming apparatus according to any one of claims 14 to 22, wherein the image forming apparatus comprises: 24. The control means is set to select the set temperature lowering mode when the temperature detected by the temperature detecting means at the time of starting the fixing device is equal to or higher than a predetermined temperature. Item 24. The image forming apparatus according to any one of items 23. 25. Another temperature detecting means for detecting the temperature at a predetermined position of the fixing device is provided, and the set temperature lowering mode is selected when the temperature detected by the other temperature detecting means is equal to or higher than the predetermined temperature. The image forming apparatus according to any one of claims 14 to 24, wherein the image forming apparatus is set as follows. 26. The control means can detect the temperature at a predetermined position of the fixing device in correspondence with the temperature detected by the temperature detection means, and selects the set temperature lowering mode when the temperature is equal to or higher than the predetermined temperature. 26. The image forming apparatus according to claim 14, wherein the image forming apparatus is set to perform.