JPH06295140A - Temperature measuring instrument and recording material guiding member for image forming device and fixing device - Google Patents

Abstract

(57) [Summary] [Objective] One of the objects of the present invention is to perform appropriate sensitivity and delay correction when a thermistor designed to have constant sensitivity and time constant in a predetermined temperature range is used. The object is to provide a temperature measuring instrument that can be used. [Structure] A circuit 3 for obtaining a temperature change rate based on a temperature g detected through a temperature sensor 1 and a conversion circuit 2 and a previously detected temperature g0 is used in a temperature change rate Δg.
(Dg / dt) is calculated, and in the sensitivity and delay correction circuit 4, it is determined which temperature range the detected temperature belongs to among the temperature ranges divided so that the sensitivity and the time constant are constant. Coefficients an and bn set for the temperature range
Therefore, the detected temperature is corrected based on the formula of f = an · g + bn · Δg.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature measuring device for measuring a rapidly changing temperature.

The present invention also relates to a recording material guide member for an image forming apparatus such as an electrophotographic copying machine or printer.

Further, the present invention relates to a fixing device which is used in an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus and which fixes an image on a recording material.

The present invention also relates to a roller-fixing type fixing device for fixing a toner image, which is used in printers, copying machines and the like, and more particularly to cleaning of a separation assisting member for separating a recording material after fixing from a roller.

[0005]

2. Description of the Related Art Conventionally, in a copying machine or a laser beam printer using an electrophotographic technique, the following fixing process by heat fixing is performed in order to fix the toner on the paper surface.

This heat fixing method is a method of melting toner by heat and fixing it on the paper surface. Therefore, when fixing at a temperature higher than a predetermined temperature, the toner adheres to the fixing device and is fixed at a temperature lower than the predetermined temperature. In this case, it becomes a factor of generating noise called fog, which deteriorates the image quality. Further, when fixing is performed at a temperature equal to or lower than a predetermined temperature, the toner is peeled off from the surface of the paper due to friction with the paper or the like, resulting in poor fixing. Therefore, at the time of fixing, it is necessary to control the temperature so that it falls within a predetermined temperature range, but normally a thermistor is used as a temperature sensor to control the temperature.

Next, another conventional example will be described. Conventionally, in an electrophotographic printer, as shown in FIG. 12, main components from transfer to fixing are 22 fixing rollers, 23 pressure rollers, 24 fixing entrance guides,
It is composed of 25 transfer rollers and 26 photosensitive drums, and guides the recording material to the pressure contact portion between the fixing roller 22 and the pressure roller 23 by the fixing inlet guide 24.

Next, another conventional example will be described. Generally, a heat roller fixing device is used as the fixing device of the image forming apparatus. The heat fixing device includes a metal fixing roller in which a halogen heater as a heat source is arranged, a rubber pressure roller pressed against the metal fixing roller, and an entrance guide for introducing the recording material into the nip between the roller and the recording material from the fixing roller. It is composed of a separating device for separating. This separating device is installed
This is because when the unfixed toner on the recording material melts, an adhesive force acts between the fixing roller and the recording material to prevent the recording material from winding around the fixing roller.

As a separation method, a plurality of separation claws are arranged in contact with each other in the axial direction of the fixing roller, and a separation method for separating the recording material directly from the fixing roller, and a separation guide which is not in contact with the fixing roller are provided in proximity. There is a curvature separation method in which the front end of the recording material is naturally separated from the fixing roller and separated immediately after the recording material is separated.

[0010]

However, the above-mentioned conventional example has the following problems. First, the conventional example using the thermistor as the temperature sensor has the following problems.

(1) Since the dynamic range is non-linear, if the sensitivity and the time constant are designed to be constant at 90 to 150 ° C., the sensitivity and the time constant differ outside the above temperature range. have.

(2) In a fixing device using a film to enable high-speed printing, a high-speed start-up control from room temperature and a sampling interval of 0.2 s during fixing are set.
Although high speed control of ec or less is required, the time constant in the above temperature range is about 0.5 to 1 sec. For this reason,
A delay occurs when measuring a phenomenon that changes faster than 0.5 sec.

Therefore, from room temperature to the temperature at the time of fixing (for example,
In order to use the thermistor for the control of high-speed start-up to 90 to 150 ° C.) and the control for fixing the high-speed temperature during fixing, the sensitivity correction and the delay correction outside the fixing temperature range are required.

On the other hand, conventionally, it is known that what can be regarded as a first-order lag system can be corrected by an equalizer. However, the nonlinear one has a problem that it is difficult to design an equalizer because the time constant and the sensitivity are not constant.

Further, in the conventional example shown in FIG. 12, paper wrinkles and gloss unevenness (in a solid black image, a glossy portion and a non-glossy portion due to unevenness of the fixing state are visually observed depending on the position X of the tip of the fixing inlet guide 24. Defect image that can be confirmed),
A fixing failure occurs such as paper wavy (a problem that paper is wavy due to unevenness of the fixing state in a solid white image).

For example, when the fixing entrance guide 24 moves in the direction A, the unevenness of gloss and the waviness of the paper are improved, but the wrinkle of the paper is deteriorated. On the contrary, fixing entrance guide 2
When 4 moves in the direction of B, the degree of paper wrinkles improves, but
The unevenness of gloss and the waviness of the paper are worse.

Therefore, there is a problem in that the position X of the fixing entrance guide 24 which can prevent all of paper wrinkles, gloss unevenness, and paper waviness cannot be found.

Further, in the case of the above-mentioned claw separation system, a claw holding member for swingably holding a plurality of separation claws and a pressure spring for abutting each claw against the fixing roller are required, and the number of parts and assembly There is a problem that the cost increases because the man-hours increase. Further, in the claw separation method, it is difficult to set the contact angle and the contact pressure of the separation claw to the fixing roller, and the surface of the fixing roller is easily scratched, and this scratch causes deterioration of image quality.

Further, for the separating claw, a member made of a heat-resistant material (for example, polyimide amide, etc.) that can withstand a temperature of about 300 ° C. and fluorine-based coating is used to improve the releasability of the toner. It was unavoidable that the toner adhered to the separation claws and was fused and fixed by the passage of the recording material. Therefore, the toner adhering to the separation claw may scrape off the toner on the next recording material, resulting in an image defect in which white streaks are left on the image. In addition, the adhered toner may adhere to the next recording material and cause an image defect that appears as a black spot on the image. Further, there are problems that the adhered toner damages the surface of the fixing roller and that the adhered toner hits the tip of the recording material, resulting in frequent occurrence of retention jam.

On the other hand, in the case of the curvature separation method, the structure is simple, but since the distance between the separation guide and the fixing roller must be set to a predetermined value, spacers are integrally attached to both ends of the separation guide. The distance between the fixing roller and the separation guide was guaranteed. However, since the separation guide and the spacer are separate parts in the value of the distance, there is an unstable factor that the influence of the dimensional tolerance of each and the variation of the assembly act. Further, it is technically difficult to stabilize the distance between the separation guide and the fixing roller, because it is difficult to maintain the dimensional accuracy of these parts and thermal deformation of the parts occurs due to the heat transmitted from the fixing roller. If this distance becomes large, jamming due to poor separation occurs, and if it becomes small, on the other hand, there is a problem in that the roller comes into contact with the fixing roller and scratches the roller surface, degrading image quality.

A first object of the present invention is to solve the above-mentioned problems and to appropriately correct sensitivity and delay even when a thermistor designed to have constant sensitivity and time constant in a predetermined temperature range is used. It is to provide a temperature measuring device capable of performing the above.

A second object of the present invention is to solve the above-mentioned object and to provide a fixing entrance guide which can prevent paper wrinkles, gloss unevenness, and paper waviness.

Further, a third object of the present invention is to solve the above-mentioned problems and to have a simple structure, but to prevent image defects due to adhesion of toner to the separating member, damage to the surface of the fixing roller, or paper jam. It is to provide a fixing device that does not generate.

[0024]

According to the first invention of the present application,
The first purpose is to measure the rate of change of the temperature detected by the temperature detecting means in a temperature measuring device having temperature detecting means set so that the sensitivity and time constant are constant within a predetermined temperature range. And at least when the detected temperature is outside the predetermined temperature range, the sensitivity and the time constant in the divided temperature range to which the detected temperature belongs among the temperature ranges divided so that the sensitivity and the time constant can be regarded as constant are And a means for correcting the detected temperature by a predetermined function related to the temperature and the rate of change of the temperature.

According to the second invention of the present application, a second object is to provide a fixing roller rotatably provided with a heating element, and a driven roller rotatably pressed against the fixing roller. The pressure roller is disposed so as to face the pressure contact portion of the fixing roller and the pressure roller, and the recording material is contacted to the pressure contact portion by contacting the surface of the recording material on the side in contact with the pressure roller. An image forming apparatus having a recording material guide member for guiding and fixing and fixing an unfixed image by heating and pressurizing an unfixed image by nipping and conveying the recording material at a pressing contact portion of the fixing roller and a pressure roller. In the vicinity of the fixing roller on the upstream side in the recording material conveying direction, a recording material guide member that is in contact with the surface of the recording material before entering the pressure contact portion is in contact with the fixing roller is provided. For the recording material guide member,
This is achieved by connecting temperature adjusting means for setting the surface temperature of the recording material guide member to a temperature lower than the surface temperature of the fixing roller.

Further, according to the third invention of the present application, the third object is to provide a fixing roller, a separation guide which is arranged in non-contact with the fixing roller and separates a recording material from the surface of the fixing roller, and the separation guide. In a fixing device that is integrally attached to both ends of the guide and has a spacer that ensures the distance between the separation guide and the fixing roller, the spacer is provided so as to extend into the sheet passing area of the recording material, This is achieved by having a separating portion that separates the end portion of the recording material from the fixing roller without contacting the fixing roller surface.

According to the fourth aspect of the present invention, the third object is to separate a pair of pressure-contacting fixing rollers for sandwiching a recording material carrying an unfixed toner image and separating the recording material from the fixing roller. In the fixing device having the separation assisting member, the separation assisting member is disposed so as to be movable in a direction away from the fixing roller, and the separation assisting member is provided in the middle of the movement track of the separation assisting member. This is achieved by arranging the cleaning member of.

[0028]

According to the first aspect of the present invention, by dividing the temperature range into a range in which the temperature sensitivity and the time constant of the temperature detecting means can be approximated to be constant, the characteristics of the temperature detecting means are Since it can be regarded as a first-order lag system, temperature correction can be performed by a predetermined simple function, and appropriate temperature correction is performed at a practical processing speed.

According to the second aspect of the present invention, the recording material guided by the recording material guide member to the pressure contact portion between the fixing roller and the pressure roller is another recording material guide member disposed near the fixing roller. Therefore, the front end of the recording material is uniformly inserted into the pressure contact portion without directly contacting the surface of the fixing roller. Therefore, the occurrence of paper wrinkles is prevented. Further, since the surface temperature of the recording material guide member arranged near the fixing roller is set lower than the surface of the fixing roller by the temperature adjusting means, the amount of heat given to the recording material immediately before the pressure contact portion is reduced, Suppresses uneven gloss and wavy paper.

Further, according to the third invention of the present application, since the spacer is provided with the separating portion for separating the paper end portion, and the spacer is extended to the paper passing area, the distance between the fixing roller and the separation guide can be accurately maintained, and the paper edge can be maintained. Stable separation of parts. That is, since the spacer is in contact with the fixing roller, the distance between the fixing roller and the separation guide is determined by the spacer component accuracy and is stable. Further, since the area where the spacer abuts the fixing roller is outside the sheet passing area, even if the spacer is soiled or the fixing roller is damaged, the conveyance of the recording paper and the image quality are not adversely affected.

Further, according to the fourth aspect of the present invention, when the separation assisting member moves in the direction away from the fixing roller, the cleaning member provided in the middle of the movement trajectory removes the toner adhering to the separation assisting member. To be done. Therefore, even if the separation assisting member moves again to the separation position of the recording material, the image on the next recording material is not damaged, and the surface of the fixing roller is not damaged, so that the separation operation is surely performed. I do.

[0032]

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 with reference to FIGS.

Since the thermistor can be regarded as a first-order lag system in a linear temperature range (in other words, a temperature range in which sensitivity and time constant can be approximated to be constant), the transfer function D (s) of the temperature characteristic of the thermistor in this range is It can be expressed as a formula.

[0035]

[Equation 1]

Here, k is sensitivity, T is a time constant, and s is Laplacian.

In this case, between the target temperature f (t) and the detected temperature g (t),

[0038]

[Equation 2]

The following relationship holds.

Since the sensitivity and the time constant change outside the above temperature range, it can be considered that the sensitivity and the time constant of the equation (2) depend on the temperature. In other words, equation (2) is

[0041]

[Equation 3]

Can be expressed as

It is not practical to calculate the equation (3) when detecting the temperature, because it takes a long calculation time. Therefore, the present invention makes the following corrections.

1. Divide so that the sensitivity and time constant are almost constant over the temperature range. By this method, the function (3) for correcting the temperature sensitivity and the delay can be approximated to an expression that facilitates the correction processing as shown in the expression (2) in each divided temperature range. 2. Adaptive temperature correction processing is performed using the correction function obtained for each of the divided temperature ranges.

The method of the present invention will be described in detail below. 1 is a configuration of a temperature measuring device according to a first embodiment of the present invention. In FIG. 1, 1 is a temperature sensor, 2 is a conversion circuit, 3 is a circuit for obtaining a temperature change rate, and 4 is a sensitivity and delay correction circuit.

The temperature sensor 1 is a temperature sensor for converting the temperature used in the temperature measuring device of the thermistor into a potential difference. The conversion circuit 2 is a circuit that multiplies the potential difference detected by the temperature sensor 1 by the sensitivity of the temperature sensor 1 and converts it into a value of an electric signal representing the temperature. The circuit 3 for obtaining the temperature change rate is a circuit for measuring the temperature change rate from the time change of the detected temperature of the conversion circuit 2. Sensitivity and delay correction circuit 4
Is a circuit for correcting the sensitivity and the delay with respect to the detected temperature from the detected temperature and the changing speed of the temperature.

In the prior art, the temperature sensor 1 and the conversion circuit 2 constitute a temperature measuring device, whereas the temperature measuring device of the present invention has a circuit 3 for determining the temperature change rate, sensitivity and delay correction. The feature is that the circuit 4 is added.

The circuit 3 for obtaining the temperature change rate and the sensitivity / delay correction circuit 4 can be implemented by software using a computer.

FIG. 2 shows the configuration of the circuit for obtaining the temperature change rate and the sensitivity and delay correction circuit in the first embodiment of the present invention. In FIG. 2, 5 is a CPU and 6 is a memory.
The memory 6 is divided into a work area 7 for processing, a program area 8 for processing for obtaining the temperature change rate, a program area 9 for correction processing of sensitivity and delay, and an area 10 for storing the relationship between each area and the correction function. The work area 7
Is further divided into a first area 7-1 and a second area 7-2.

FIG. 3 is a flow chart of the processing for obtaining the temperature change rate and the sensitivity and delay correction processing in the first embodiment of the present invention. In FIG. 3, 11 is a temperature detection process, 12 is a process for obtaining a temperature change rate, and 13 is a process for obtaining a temperature in which sensitivity and delay are corrected.

The operation will be described below. First, CPU5
Is a temperature detection process 11 and a temperature change speed calculation process 1 based on the program stored in the program area 8.
Do 2. In the temperature detection process 11, the temperature g is detected by the CPU 5 via the temperature sensor 1 and the conversion circuit 2. At this time, the detected temperature g0 before the predetermined unit time is already stored in the first area 7-1 of the work area 7.

Then, the process 12 for obtaining the temperature change rate.
At, the difference between the temperature g0 previously stored in the first area 7-1 of the work area 7 and the detected temperature g obtained in the temperature detection processing 11, that is, the temperature change rate Δg (dg / dt) is obtained. Then, the detected temperature g is stored in the first area 7-1 and the temperature change rate Δg is stored in the second area 7-1.

Next, the CPU 5 detects the sensitivity from the detected temperature g stored in the first area 7-1 and the temperature change rate Δg stored in the second area 7-2 based on the program stored in the program area 9. And processing for obtaining the temperature with the delay corrected.

FIG. 4 is a flow chart of the processing 13 for obtaining the temperature in which the sensitivity and the delay are corrected. In FIG. 4, 14 is a range determination process, and 15 is a correction process.

First, in the range determination process 31, the temperature range to which the temperature g belongs is determined depending on whether or not the detected temperature g1 satisfies the condition of gm <g1 <gm + 1.

Next, in the correction process 32, the temperature f corrected for the sensitivity and the delay is obtained by using the correction function stored in the area 16 of the memory 12.

An example of this correction function is shown in the following equation (4). This equation holds when the temperature range is divided so that the sensitivity and the time constant are constant. For example, when the range obtained in the range determination process 31 is the temperature range n, the correction temperature f is It looks like this:

[0058]

(4) if gn <g <gn + 1 then f = an · g + bn · Δg --- (4)

Here, f is the temperature corrected for sensitivity and delay,
g is the detected temperature, Δg is the temperature change rate, n is a number for distinguishing the ranges, [gn, gn + 1] is the temperature range of the range n, and an and bn are constants related to sensitivity and time constant.

As described above, by dividing the temperature range so that the sensitivity and the time constant are substantially constant and using the correction function obtained for each divided temperature range, it is possible to obtain an appropriate value within a practical processing speed. It is possible to perform various temperature corrections.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIGS. The same parts as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the present embodiment, the relationship between each divided temperature range and the correction function described in the first embodiment is represented by a fuzzy rule, the fuzzy rule, the detected temperature g and the temperature change rate Δg.
From this, the corrected temperature f is obtained by fuzzy inference.

FIG. 5 is a flow chart of the second embodiment of the present invention.
In FIG. 5, 16 is a process for obtaining the degree of matching with each fuzzy rule, and 17 is a correction process by fuzzy inference.

The operation will be described below. In Example 1, the division was performed so that the sensitivity and the time constant were constant in each temperature range, but this method is such that a curved line is expressed by a broken line (a group of straight lines), and when the curvature is large, the number of divisions is large. , And the accuracy of approximation with broken lines becomes poor. In order to solve this problem, the present embodiment utilizes the nonlinear interpolation effect of fuzzy inference, reduces the number of divisions, and improves the approximation accuracy. Specifically, the crisp relationship represented by the equation (4) is replaced with a fuzzy relationship, and the correction process is performed by fuzzy inference.

A specific example will be described below. The formula (4) replaced by fuzzy rules is

[0066]

[Equation 5] if g is Rn then fn = an · g + bn · Δg −−− (5)

It can be expressed as

The fuzzy rule of the equation (5) expresses that "if the detected temperature g is Rn, the temperature fn in which the sensitivity and the delay are corrected by the correction function fn = an.g + bn.Δg can be obtained".

FIG. 6 shows the relationship between the temperature range Rn and the membership function. In FIG. 6, the membership function indicates the degree to which the detected temperature g belongs to each temperature range, and since the membership functions overlap at the boundary of each region, a plurality of fuzzy values are used to correct a certain detected temperature g.・ There are cases where rules are used. This is the reason that fuzzy reasoning has a non-linear interpolation effect.

The process 16 for obtaining the degree of matching with each fuzzy rule is for obtaining the degree of involvement of each fuzzy rule (degree of belonging), and if the membership function of the temperature range n is Rn (g). , Fuzzy in temperature range n
The matching degree with the rule (5) is Rn (g).

The correction processing 17 based on fuzzy inference is performed by the matching degree Rn (g) with each fuzzy rule and the correction function fn =
From an · g + bn · Δg,

[0072]

[Equation 6]

By the fuzzy inference shown in the equation (6), the temperature f corrected for sensitivity and delay is obtained. When high-speed processing is required, it is possible to store the result of previously calculating equation (6) in the memory as a lookup table of the detected temperature and the correction temperature with respect to the temperature change rate.

<Third Embodiment> Next, a third embodiment of the present invention will be described with reference to FIGS.

7 and 8 show the third embodiment of the present invention,
FIG. 8 is a view of FIG. 7 viewed from the S direction. 7 and 8, 21 is a fixing guide member having a plurality of ribs in Embodiment 3 of the present invention, 22 is a fixing roller, 23 is a pressure roller,
Reference numeral 24 is a fixing inlet guide, 25 is a transfer roller, 30 is a cooling fan, 27 is a fixing guide member 21, and is a heat conducting member for cooling the surface of the fixing guide member 21 by the air of the cooling fan 30, and 28 is a recording device. It is a material. Reference numeral 26 is a photosensitive drum.

In the above structure, the recording material 28 is fed from the transfer roller 25 toward the fixing entrance guide 24 as shown in FIG.
After being conveyed above, it first contacts the fixing guide member 21, and then is fed to the nip portion between the fixing roller 22 and the pressure roller 23.

Here, the surface of the fixing roller 22 is, for example, 1.
While the temperature is controlled to be 80 ° C., the surface of the fixing guide member 21 that comes into contact with the recording material 28 is heated to, for example, 10 ° C. by the cooling fan 30 and the heat conductive member 27. It is assumed that the temperature is set low. However, the temperature is set so that there is no low temperature offset.

As a result, the fixing guide member 21 has the effect of preventing the occurrence of paper wrinkles by the contact of the leading end of the recording material 28 with the fixing roller 22 so that the recording material 28 is evenly inserted into the nip portion. It becomes possible. Further, since the surface temperature of the fixing guide member 21 is lower than the surface of the fixing roller 22 by about 10 ° C., the amount of heat given to the recording material 28 immediately before the nip portion is small, and the unevenness of gloss and the degree of waviness of paper are fixed. This is considerably better than in the case of directly contacting the fixing roller 22 without using the guide member 21.

Since the fixing guide member 21 is installed on the image surface, a rib is formed on the fixing guide member 21 in order to prevent toner stains when an unfixed image contacts the fixing guide member 21. However, the contact area with the image is reduced as much as possible.

Further, the fixing roller 22 of the fixing guide member 21
A method of setting a temperature lower than the surface of the fixing roller 22 without using a cooling fan, a heat conducting member, or the like by attaching a heat insulating member or the like to the side to provide a heat insulating effect may be used.

As described above, the fixing guide member 2 set to have a surface temperature lower than the surface temperature of the fixing roller 22.
1 is provided in the vicinity of the fixing roller 22 to lower the temperature control temperature of the fixing roller 22 and sacrifice the fixing property without taking measures such as paper wrinkles, uneven gloss, and wavy paper. It has become possible to prevent the occurrence of.

<Embodiment 4> Next, an embodiment of the present invention will be described with reference to FIG.
It will be described based on. The same parts as those in the third embodiment are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 9, reference numeral 21a denotes a fixing guide member, which has a structure capable of swinging around the rotation center axis of the fixing roller 22 by being biased by the spring 29. However, the longitudinal direction has the same shape as in FIG. 7.

Next, in the above configuration, only the contents different from those of the third embodiment will be described. When the recording material 28 comes into contact with the fixing guide member 21a, the fixing guide member 21a moves to the spring 2
In opposition to the force of 9, the recording material 28 and the recording material 28 rotate counterclockwise to the extent that they do not hit the nip portion of the fixing device. After the recording material 28 passes, it is returned to a predetermined position while being rotated clockwise by the force of the spring 29.

With such a structure, the fixing guide member 21a swings around the rotation center axis of the fixing roller 22, so that the impact when an unfixed image comes into contact with the fixing guide member 21a can be softened. Therefore, it is possible to combine the effect that the toner stain hardly occurs in addition to the effect of the third embodiment.

<Fifth Embodiment> Next, a fifth embodiment of the present invention will be described with reference to FIG. The same parts as those in the third embodiment are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 10, 21b is a fixing guide member,
A cylindrical member that can rotate around the central axis, and the surface layer is PF
It is covered with a material having good toner releasability such as A and PTFE.

With such a configuration, in addition to the effect of the third embodiment, it is possible to have the effect that toner stains are unlikely to occur even when an unfixed image comes into contact with the fixing guide member 21b. .

When the surface temperature of the fixing guide member 21b is not much lower than the surface temperature of the fixing roller 22, the temperature difference is established by connecting to the cooling means such as the cooling fan 26 and the heat conducting member 27 as in the third embodiment. Needless to say, to have.

<Sixth Embodiment> Next, a sixth embodiment of the present invention will be described with reference to FIG. The same parts as those in the third embodiment are designated by the same reference numerals and the description thereof will be omitted.

In FIG. 11, 21c is a fixing guide member,
It is composed of multiple spur groups.

With such a structure, in addition to the effect of the third embodiment, even if an unfixed image comes into contact with the fixing guide member 21c, the spur spurs, so that toner stains are less likely to occur. When the surface temperature of the fixing guide member 21c is not much lower than the surface temperature of the fixing roller 22, the cooling fan 30 and the heat conducting member 2 are the same as in the third embodiment.
It goes without saying that the temperature difference is provided by connecting to a cooling means such as 7.

<Seventh Embodiment> Next, a seventh embodiment of the present invention will be described with reference to FIGS.

13 to 18 are views showing a seventh embodiment of the present invention. FIG. 13 is a perspective view showing a spacer portion, and FIG.
4 is a main sectional view including a spacer portion of the fixing device, FIG. 15 is a sectional view of the center of the fixing device, FIG. 16 is a front view of the fixing device, and FIG.
[Fig. 3] is a diagram showing the configuration from the top surface direction.

In FIG. 14, 101 is a fixing frame,
102 is an aluminum fixing roller, 103 is a rubber pressure roller that is in pressure contact with the fixing roller, 104 is a halogen heater as a heat source, 105 is a fixing entrance guide, and 10
6 is an upper cover, 107a is a pressure spring for pressing the pressure roller against the fixing roller via a pressure roller bearing (not shown), 108 is a lower guide, 109 is a connector, 110 is a separation guide, and 110-1 is 110-1. Positioning boss, 111, 112
Is a fixing roller bearing for instructing the fixing roller to slide.
113a and 113b are spacers, 114 is a screw, 115
a and 115b are separation guide springs.

The fixing roller 102 is rotatably supported at both ends by fixing roller bearings 111 and 112, and the fixing roller bearings 111 and 112 are held by the fixing frame 101. The pressure roller 103 is supported at both ends by a pressure roller bearing (not shown), and is pressed against the fixing roller 102 with a predetermined pressure by a pressure spring 107a via the bearing to form a nip portion. . The halogen heater 104 is held in the central portion of the fixing roller by a member (not shown) and generates heat during operation to heat the fixing roller 102. The fixing entrance guide 105 is the fixing frame 101.
The recording paper is held at its both ends, and the leading edge of the recording paper is introduced into the nip portion of the roller. The upper cover 106 insulates and protects the fixing device, and the lower guide 108 controls the sheet conveyance after passing through the nip. Further, the connector 109 electrically connects the fixing device and the main body. The tip of the separation guide 110 is the fixing roller 1.
The leading edge of the recording paper is separated from No. 02, and the paper conveyance is also controlled as a whole. A spacer 113a is positioned at both ends of the spacer 113a through a round hole 113a-1 and a round elongated hole 113a-2, which are engaged with the boss 110-1 of the separation guide 110, and fixed by screws 114. In addition, the separation guide 110 disposes the fixing roller 10 on the fixing frame 101.
Positions where the spacers 113a and 113b on both sides are in contact with the fixing roller 102 by means of separation guide springs 115a and 15b, which are attached so as to be movable in the direction of the center of the separation guide 110 on one side and the fixing frame 101 on the other side. It is held stably.

In the spacer 113a, 113
a-3 is a portion that contacts the fixing roller 102, and 113a
-4 is a portion having a separating function of the end portion of the recording paper, and as shown in FIG. 17, the distance (X1) from the surface of the fixing roller is 0.
It is 2 mm and extends in the axial direction outside the effective printing area, for example, to a position 3 mm from the edge of the paper within the recording paper.

As shown in FIG. 17, the distance between the separation guide 110 and the surface of the fixing roller is different between the end and the center at room temperature, and is designed to be 0.4 mm for X2 and 0.7 mm for X3, for example.

In the structure of the present invention, the separation guide 110 is integrally provided with the spacer having the separation portion 113a-4.
Moreover, since the separation guide is movable toward the center of the fixing roller, the value of the distance X1 between the separating portion 113a-4 of the spacer 113a and the fixing roller is simply determined only by the component accuracy of the spacer 113a. Spacer 113 as shown
Has a small and simple shape, so that it is easy to control the size of a single component, and thermal deformation is so small that it can be ignored. Therefore, the spacer 113a can be separated even when it is incorporated in the fixing device or under heating. The values of the distance X1 between the fixing roller 113a-4 and the fixing roller 102 are stable.

Therefore, in separating the recording paper,
Since the separation of the paper edge portion is more difficult for the paper to separate from the surface of the fixing roller than the central portion of the paper, the distance X1 between the fixing roller 102 and the separating portion 113a-4 of the spacer 113a has a small value and has a strict accuracy. Although required, this configuration sufficiently satisfies these specifications. Also, the fixing roller 1
If the distance between 02 and the separating portion 113a-4 becomes too large, separation may occur, which may cause jamming or ear breakage.
On the other hand, if it is too close, it will contact the fixing roller 102 and cause scratches. In addition, according to our study, the distance is 0.2 mm or less in the non-printing area even if it is not in contact with the fixing roller 102.
Separation part is soiled with developer (toner), recording paper is soiled,
It may cause a jam. In this configuration, the separating portion 113a-4 provided on the spacer 113a is the fixing roller 10
Although the distance from 2 is as small as 0.2 mm, since it is installed only outside the printing area of the recording paper, the above-mentioned stain by the developer does not occur and the separation performance is not adversely affected.

In the separation guide 110, the distance between the fixing roller 102 and the fixing roller 102 is changed between the end portion and the central portion, and the distance at the central portion is set to be 0.3 mm wider than that at the end portion. This setting considers the thermal deformation of the separation guide, and the distance X2 between both ends.
Since the spacer 113a is in contact with the fixing roller 102 in the vicinity thereof, it does not change even at high temperature, but the distance (X3) at the center is about 0.3 mm in our study.
No. 02 was thermally deformed in the approaching direction. This configuration cancels out this thermal deformation. At high temperature, that is, when the printer is operating, the distance between the fixing roller 102 and the separation guide 110 is uniformly set to 0.4 mm in the fixing roller axial direction, and stable separation is achieved. It is also possible to prevent the separation portion from being soiled by the developer.

<Embodiment 8> Next, Embodiment 8 of the present invention will be described in detail with reference to FIGS. Example 7
The members having the same functions and shapes as those of are denoted by the same symbols, and the repetitive description will be omitted.

In the eighth embodiment, a part of the fixing roller bearing is cut out, and the spacer is brought into contact with the surface of the fixing roller by utilizing this part. FIG. 18 is a perspective view showing a spacer portion, and FIG. 19 is a sectional view showing the spacer portion. In the figure, 120a is a fixing roller bearing, and 120a
-1 is a notch part.

Also in this embodiment, since the spacer 113a having the separating portion 113a-4 is integrally attached to the separating guide 110 and the spacer 113a is brought into direct contact with the fixing roller, the separation of the end portion of the recording paper is prevented. It has the same effect as that of the eighth embodiment. Further, in the structure of the fixing device, it is necessary to bring the spacer 113a into contact with the fixing roller 102 at a position avoiding the maximum paper passing width, and also to arrange the fixing roller bearing at a position avoiding the paper passing region. In Example 7, FIG.
8, a cutout portion 120-1 is provided in a part of the fixing roller bearing 120a, and the spacer 1 is formed in this portion.
13a was brought into contact with the surface of the fixing roller 102. That is, the fixing roller 10 is provided on the same peripheral surface of the fixing roller 102.
Since the second support and the spacer are in contact with each other, the size in the axial direction can be reduced. Further, even with this configuration, since the fixing roller 102 is pressed upward by the pressing roller 103, The part where the fixing roller bearing 120a slides with the fixing roller 102 is the upper part of the inner peripheral part of the bearing, while the notched part of the bearing is the lateral part, so the bearing performance is impaired by the notch. There is no.

<Ninth Embodiment> Next, a ninth embodiment of the present invention will be described in detail with reference to FIGS. The members having the same functions and the same shapes as those in the seventh embodiment are designated by the same symbols, and the repetitive description will be omitted.

In the ninth embodiment, when the spacer is attached to the separation guide, the spacer is movably provided in the central direction of the fixing roller, and the distance X1 between the spacer separating portion and the fixing roller is influenced by the shape of the spacer mounting portion. However, the structure is determined only by the dimensions of the spacers.

FIG. 20 is a sectional view of a fixing device including a spacer portion. Reference numeral 130 denotes a separation guide, which is different from the separation guide 110 of the seventh embodiment only in the spacer mounting portion. 1a and a boss 130-2a are provided. 131a is a retaining ring with a claw, 132a is a spacer, and 132a-1 is a round hole and an oval hole that engage with the stepped boss 130-1a. As shown in FIG. 20, since the length of the lower portion of the stepped boss 130-1a is slightly longer than the size of the spacer 132a, the spacer 132a has a play in the direction of the fixing roller 102 and a retaining ring 131a with a claw.
It is attached to the separation guide 130.

Also in this embodiment, the separation guide 130 is pressed against the fixing roller 102 by the separation guide spring 115a, but the spacer 132a is slightly movable in the fixing roller direction.
The positional relationship of a in the axial direction of the fixing roller is not affected by the shape and size of the seating surface of the mounting portion, and is determined only by the plate thickness dimension of the abutting portion of the spacer 132a.
The accuracy of the distance between the separated portion of 30 and the fixing roller 102 is further improved. Further, the dimensional control of the spacer 132a is further facilitated.

<Embodiment 10> FIG. 22 is a schematic structural view showing an embodiment of the present invention. 22A is a sectional view, FIG.
(B) is a top view showing the composition of the separation nail and cleaning member of the present invention.

Reference numeral 201 denotes a heat fixing roller having an outer diameter of 20 m.
A core metal of an aluminum pipe having an inner diameter of 2 mm and a thickness of 2 mm is coated with a resin layer of PFA with a thickness of several tens of μm in order to improve releasability. A halogen heater is provided inside the fixing roller 201, and the thermistor temperature detecting element (not shown) controls the heating of the fixing roller to a predetermined temperature.

Reference numeral 202 denotes a pressure roller, which is formed of a 4 mm-thick silicone rubber having heat resistance and good releasability around a stainless steel core having a diameter of 12 mm. The pressure roller 202 is pressed against the fixing roller 201 by a spring member (not shown).

Reference numeral 203 denotes a separating claw, which has a temperature of 250 to 30.
It is a member formed of polyimideamide, which is a heat-resistant resin that can withstand about 0 ° C., and is provided with fluorine-based coating in order to improve the releasability of the toner.

A plurality of separation claws 203 are attached to the support shaft 204, and a plurality of separation claws 203 are attached so as to adapt to the size of the recording material to be passed.

The separation claw 203 is pressed against the fixing roller 201 by a coil spring 205 with a pressing force of several g.

The support shaft 204 rotates in the direction shown by rotating the lever 206 about the fulcrum 205. Reference numeral 207 is a return spring of the support shaft 204, and 208 is a stopper of the support shaft 204, which fixes the separation claw 203 at a predetermined position.

The cleaning member 20 is placed on the rotation locus of the separation claw 203.
9 is provided and is made of a heat-resistant fibrous felt material.

In the figure, 210 is a toner receiver for receiving the toner falling from the cleaning member 209, 211 and 212 are recording material guides on the paper discharge side, 213 is an inlet guide, and P is a recording material.

In the above structure, by rotating the lever 206, the separation claw 203 is rotated in a direction away from the fixing roller 201, and the cleaning member 209 in the rotation trajectory removes the toner attached to the separation claw. To be cleaned.

When the lever 206 is returned, the separation claw is cleaned again by the cleaning member and set at a predetermined position.

Since the separation claw member is provided with the fluorine-based coating, the toner adheres, but the felt of the cleaning member comes into contact with the toner to separate the toner, so that the above-described structure is effective. . Further, in order to improve the releasability of the toner of the separation claw 203, the cleaning member felt may slightly contain silicone oil.

By changing the length of fibers of the cleaning member, the cleaning member can be placed in contact with the separation claw 203 from one side, from above, and from below.

<Embodiment 11> Next, an embodiment 11 of the present invention.
Will be described with reference to FIGS. 23 to 26. The same parts as those of the tenth embodiment are designated by the same reference numerals and the description thereof will be omitted.

Although the structure of the fixing device is described in the tenth embodiment, a laser printer using the fixing device according to the present invention will be described.

As shown in FIG. 26, the structure of the laser printer is such that the paper P is fed from the paper feed section including a cassette 231 for accommodating the paper P and a paper feed roller 232.
2 and the photosensitive drum 235 in the process cartridge 234 by the registration roller 233.
Supply in synchronization with the rotation of.

In the vicinity of the photosensitive drum 235 in the process cartridge 234, a corona charger 236 for uniformly charging the surface of the photosensitive drum 235 is arranged.

On the uniformly charged drum 235, a laser scanner 23 is responsive to an external control signal.
7, the photosensitive drum 235 is exposed to the light information, and an electrostatic latent image is formed.

Next, the electrostatic latent image is developed into a toner image by the developing device, and is transferred onto the conveyed paper P at the transfer portion provided with the transfer charger 239.

The residual toner, paper dust, etc. on the surface of the photosensitive drum 235 is cleaned by a cleaning device 240 having a blade.
Removed by.

The sheet P on which the toner image has been transferred is separated from the photosensitive drum 235 due to the curvature of the photosensitive drum 235, and is fixed via the conveyance guide 241 to the fixing device 400 according to the present invention.
Is fixed in.

After that, the sheet P changes its direction upward and is ejected to the sheet ejection tray 244 by the sheet ejection roller 243 through the conveyance roller 242.

In this structure, the cassette 231 can be pulled out from the printer casing to the right side in the drawing,
When setting the paper, pull it out.

The upper cover 200, which includes the paper discharge tray 244 and fixes the process cartridge 234, can be opened upward from the one-dot broken line A portion in the drawing around the fulcrum 245, and the paper can be exchanged at the process cartridge 234 and transferred at the transfer portion. Jam is processed.

The cover 3 on the sheet discharge side including the transport roller 242
00 is centered around the fulcrum 246 from the one-dot broken line B part in the figure,
The configuration is such that it can be opened to the left in the figure, and jam processing of paper at the fixing device 400 and the paper discharge unit can be performed.

FIG. 23 is a schematic diagram showing an embodiment of the fixing device and the discharge cover of the printer of the present invention.

In the figure, the paper discharge cover 300 is a lever 301 which rotates about the fulcrum 246 in the opening direction.
The lever is fixed to and rotates together with the paper discharge cover. The structure of the separation claw 203 is similar to that of FIG. 20 of the tenth embodiment, but the spring 214 is hooked in the direction to open the separation claw 203. In this configuration, when the discharge cover 300 is closed, the lever 301 presses the fixing side lever 206 to fix the separation claw at a predetermined position, or when the discharge cover 300 is opened, the lever 3 is pressed.
01 is retracted to the paper discharge side, and the separation claw 203 is rotated by the spring 214. By this rotation, the separation claw 203 is cleaned by a cleaning member (not shown).

Similarly, FIG. 24 is a schematic structural view showing the cassette 231 and the separation claw 203.

In the figure, the lever 247 is interlocked with the cassette 231, and the cassette 231 is centered on the fulcrum 248.
Rotate by taking in and out.

When the cassette 231 is in the set state, the rear end of the cassette 231 pushes the lever 247 to fix the separation claw at a predetermined position. When the cassette 231 is pulled out, the separation claw 203 is opened by the spring 214. And the lever 247 also rotates. Cleaning is performed by the movement of the separation claw 203.

FIG. 25 is a schematic diagram showing the relationship between the process cartridge 234 and the separating claw.

A lever 249 in the figure is a lever that rotates depending on the presence or absence of the process cartridge 234, and is a fulcrum 25.
The fixing device side lever 206 is contacted via 0. In the state where the process cartridge 234 is set, the levers 249 and 206 rotate due to the own weight of the cartridge 234, and the separation claw 203 is fixed at a predetermined position. , The separation claw 203 also rotates and is cleaned by a cleaning member (not shown).

Although the above description has been made for each case, it is possible to combine them and rotate the separation claw 203 in each state.

[0142]

As described above, according to the first invention of the present application, the temperature range is divided so that the sensitivity and the time constant of the temperature detecting means are substantially constant, and the correction is made for each divided temperature range. Since the delay correction can be easily realized by using the function, it has become possible to accurately measure the temperature of the phenomenon in which the temperature changes rapidly. Further, since high-speed temperature change can be measured with high accuracy, it can be used for controlling a phenomenon accompanied by high-speed temperature change. Furthermore, since the sensitivity correction and the delay correction can be realized at the same time, the usable temperature range can be expanded.

Further, according to the second invention of the present application, a portion upstream of the pressure contact portion between the fixing roller and the pressure roller in the recording material conveying direction,
By providing a recording material guide member having a surface temperature lower than the surface temperature of the fixing roller in the vicinity of the fixing roller, it is possible to uniformly insert the leading end of the recording material into the pressure contact portion and prevent the occurrence of paper wrinkles. Further, since the surface temperature of the recording material guide member is lower than that of the surface of the fixing roller, the amount of heat applied to the recording material immediately before the nip is reduced, and it is possible to prevent uneven glossiness and paper waviness.

Further, according to the third invention of the present application, since the spacer member having the separating function is attached to both end portions of the separating guide, the distance between the separating portion of the spacer and the fixing roller is determined only by the size of the spacer component and easily separated. It can be performed.

Further, according to the fourth invention of the present application, since the separation claw is moved and moved to be cleaned by the cleaning member, for example, the capacity of the paper in the cassette (250
Number of printable sheets of process cartridge (30 sheets)
The separation claws of the fixing device are automatically cleaned at regular intervals of (00 sheets) or at any time such as paper jam processing. By providing a good image as this effect and preventing the fixing roller from being damaged, it becomes possible to provide a highly durable fixing device.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a temperature measuring device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a circuit for obtaining a temperature change rate and a sensitivity and delay correction circuit according to the first embodiment of the present invention.

FIG. 3 is a flow chart of a process of obtaining a temperature change rate and a process of correcting sensitivity and delay according to the first embodiment of the present invention.

FIG. 4 is a flowchart of a process for obtaining a temperature in which sensitivity and delay are corrected according to the first embodiment of the present invention.

FIG. 5 is a flowchart of a process of obtaining a temperature in which sensitivity and delay are corrected according to the second embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between a temperature range Rn and a membership function in Example 2 of the present invention.

FIG. 7 is a perspective view showing a schematic configuration of a device according to a third embodiment of the present invention.

FIG. 8 is a cross-sectional view of the device of Example 3 of the present invention viewed from the S direction in FIG. 7.

FIG. 9 is a cross-sectional view showing a schematic configuration of a device of Example 4 of the present invention.

FIG. 10 is a perspective view showing a schematic configuration of a device according to a fifth embodiment of the present invention.

FIG. 11 is a perspective view showing a schematic configuration of a device according to a sixth embodiment of the present invention.

FIG. 12 is a sectional view showing a conventional image forming apparatus.

FIG. 13 is a perspective view showing a spacer portion according to a seventh embodiment of the present invention.

FIG. 14 is a sectional view of a fixing device according to a seventh embodiment of the present invention.

15 is a sectional view of the center of the fixing device shown in FIG.

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

FIG. 17 is a diagram showing the configuration of the fixing device of FIG. 14 as seen from the upper surface direction.

FIG. 18 is a perspective view showing a spacer portion according to an eighth embodiment of the present invention.

FIG. 19 is a sectional view of a spacer portion according to an eighth embodiment of the present invention.

FIG. 20 is a sectional view of a fixing device according to a ninth embodiment of the present invention.

FIG. 21 is a perspective view of a spacer portion according to a ninth embodiment of the present invention.

FIG. 22 is a schematic sectional view of a fixing device according to a tenth embodiment of the invention.

FIG. 23 is a cross-sectional view showing the relationship between the separation assisting member and the paper discharge unit according to Embodiment 11 of the present invention.

FIG. 24 is a cross-sectional view showing the relationship between the separation assisting member and the paper cassette in Embodiment 11 of the present invention.

FIG. 25 is a schematic cross-sectional view showing the relationship between the separation assisting member and the process cartridge in Embodiment 11 of the present invention.

FIG. 26 is a sectional view showing a laser printer equipped with a fixing device according to an eleventh embodiment of the present invention.

[Explanation of symbols]

1 Temperature Sensor (Temperature Detecting Means) 2 Conversion Circuit 3 Circuit for Obtaining Temperature Change Speed 4 Sensitivity and Delay Correction Circuits 21, 21a, 21b, 21c Fixing Guide Member (Abutting on the surface of the recording material that contacts the fixing roller) Recording material guide member 22 Fixing roller 23 Pressure roller 24 Fixing entrance guide (recording material guide member that contacts the surface of the recording material that contacts the pressure roller) 27 Heat conduction member (temperature adjusting means) 30 Cooling fan (temperature Adjusting means) 102 fixing roller 110 separation guide 113a spacer 113a-4 separating section 201 heat fixing roller (fixing roller) 202 pressure roller (fixing roller) 203 separation claw (separation auxiliary member) 209 cleaning member

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Haruki Okuma 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (15)

[Claims] 1. A temperature measuring instrument comprising temperature detecting means set so that the sensitivity and the time constant are constant within a predetermined temperature range, and means for measuring the rate of change of the temperature detected by the temperature detecting means, At least when the detected temperature is outside the predetermined temperature range, the sensitivity and the time constant in the divided temperature range to which the detected temperature belongs among the temperature ranges divided so that the sensitivity and the time constant can be regarded as constant are A temperature measuring device comprising means for correcting the detected temperature by a predetermined function related to the rate of change of temperature. 2. The predetermined function is expressed by multiplying each of the detected temperature and the temperature change rate by a predetermined coefficient corresponding to each divided temperature range, and adding them.
The temperature measuring device according to claim 1, wherein the function and coefficient are stored in the means for correcting the detected temperature. 3. A means for storing a fuzzy rule representing a relationship between a divided temperature range and a predetermined function, and a fuzzy inference means for obtaining a temperature corrected by fuzzy inference based on the fuzzy rule, the detected temperature and the rate of change of the temperature. The temperature measuring device according to claim 2, further comprising: 4. The temperature measuring device according to claim 1, wherein the temperature detecting means is a thermistor. 5. A fixing roller which rotatably includes a heating element, a pressure roller which is pressed against the fixing roller and is rotatably driven, and the fixing roller and the pressure roller. A recording material guide member which is disposed so as to face the pressure contact portion and contacts the surface of the recording material on the side in contact with the pressure roller to guide the recording material to the pressure contact portion; In an image forming apparatus that heats and presses an unfixed image to fix the unfixed image by nipping and conveying the recording material at the pressure contact portion of the pressure roller, in the vicinity of the fixing roller on the upstream side of the pressure contact portion in the recording material conveyance direction. A recording material guide member is provided which is in contact with the surface of the recording material that is in contact with the fixing roller before entering the pressure contact portion, and the recording material guide member has a surface temperature of the recording material guide member. At a temperature lower than the surface temperature of the fixing roller. An image forming apparatus characterized in that a temperature adjusting means for setting the frequency is connected. 6. The image forming apparatus according to claim 5, wherein the recording material guide member that contacts the surface of the recording material that contacts the fixing roller has a plate shape. 7. The image forming apparatus according to claim 6, wherein a rib is provided on the recording material guide member that contacts the surface of the recording material that contacts the fixing roller. 8. The surface of the recording material guide member that contacts the surface of the recording material that contacts the fixing roller is coated with a material having a good releasability for the developer. Item 7. The image forming apparatus according to Item 7. 9. The recording material guide member, which comes into contact with the surface of the recording material that is in contact with the fixing roller, is capable of swinging about the rotation center axis of the fixing roller by contact with the recording material. Item 6. The image forming apparatus according to Item 6. 10. The image forming apparatus according to claim 5, wherein the recording material guide member that contacts the surface of the recording material that contacts the fixing roller has a cylindrical shape. 11. The image forming apparatus according to claim 5, wherein the recording material guide member that contacts the surface of the recording material that contacts the fixing roller is a plurality of spur groups. 12. A fixing roller, a separation guide that is disposed in non-contact with the fixing roller and separates a recording material from the surface of the fixing roller, and is integrally attached to both ends of the separation guide. In a fixing device having a spacer for ensuring the distance of the roller, the spacer is provided so as to extend into the sheet passing area of the recording material, and the end portion of the recording material does not contact the surface of the fixing roller. A fixing device having a separating portion separated from a fixing roller. 13. The fixing device according to claim 12, wherein the separation guide is curved in a direction in which the center of the separation portion separates from the fixing roller in the fixing roller axial direction. 14. A fixing device comprising a pair of pressure-fixing fixing rollers for sandwiching a recording material carrying an unfixed toner image, and a separation assisting member for separating the recording material from the fixing roller. Is disposed so as to be movable in a direction away from the fixing roller, and a cleaning member for the separation assisting member is disposed in the middle of the movement track of the separation assisting member. apparatus. 15. The movement of the separation assisting member is performed by opening / closing a maintenance / inspection door of an image forming apparatus main body provided with a fixing device,
15. The fixing device according to claim 14, wherein the fixing device is performed in conjunction with an attaching / detaching operation of the recording material cassette or in association with at least one of an attaching / detaching operation of the process cartridge.