JPH08234597A - Devices for controlling biasing of belt fixing device and image forming device - Google Patents

Abstract

PURPOSE: To always stably performing transport and travel of a belt, in always adequately maintaining the belt biasing control operation, regardless of an external condition change giving effect of the belt biasing control, by providing respectively specific control means, state quantity detection means, regulation means and calculation means. CONSTITUTION: The belt biasing control means controls the belt biasing in the direction orthogonal to the moving direction so as to align the position of the belt driven to move in the direction orthogonal to the moving direction, a state quantity detection means detects or inputs the state quantity in connection with the biasing control by the biasing control means. Namely, a control circuit 100 controls a motor 5 of a displacing mechanism 80 of a tension roller 8 rotated in a forward or a backward direction based on the belt biasing position information detected and inputted by belt biasing position detection means. A regulation means relates the state quantity with the manipulated variable at the time of performing the biasing control by the biasing control means as a nonlinear regulation. A calculation means calculates the manipulated variable according to the regulation outputted from the regulation means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt deviation control device, a fixing device, and an image forming apparatus.

[0002]

2. Description of the Related Art For example, a belt (film) fixing type apparatus using a thin film belt (fixing film) that is moved and driven is one of the practical apparatus for an image fixing apparatus in an image forming apparatus such as an electrophotographic copying machine. (Japanese Patent Laid-Open No. 63-3
13182, etc.).

This is because a heat-resistant, thin-film endless belt is suspended and supported between at least two members and is rotationally driven so that the recording material to be image-fixed is brought into close contact with the outer surface of the belt. The heat of the heating element placed inside the belt is applied to the recording material through the belt to heat and fix the image during the close contact conveyance process. There are advantages such as low power consumption, excellent quick start, and power saving. Some belts are designed to generate heat by electromagnetic induction.

Thus, in the device for moving and driving the belt like the device of the above example, the belt is orthogonal to the moving direction of the belt along the longitudinal direction of the member supporting the belt in the course of the belt moving process. Direction (hereinafter referred to as the belt width direction), it tends to move to one end side or the other end side to a greater or lesser degree, and naturally shifts from the reference position in the belt width direction.

The factors of the positional deviation due to the deviation of the belt include parallelism between members that suspend and support the belt, and twisting. However, there is a limit to improving the accuracy of these members. It is difficult to prevent the above-mentioned movement toward the belt only by improving the accuracy.

In the image fixing apparatus of the belt fixing system of the above example, since the belt is a thin film having a thickness of less than 40 μm and the material is a heat resistant material such as polyimide having a low elasticity, the deviation of the belt is It cannot be pressed down by being regulated by ribs or by making the shape of the belt conveying roller as a belt suspension tension supporting member into, for example, a crown shape.

Therefore, in such a device, it is known to provide a belt deviation control mechanism as a means for stably conveying the belt. As such a belt deviation control mechanism, a means for detecting the deviation position of the belt in the width direction is provided, and based on the control amount by the position and the deviation direction, among the belt suspension tension supporting members such as the belt conveying roller. The belt deviation direction is controlled by steplessly displacing the inclination of at least one axis with a motor, etc., and the belt deviation movement is reciprocally moved infinitely within a very narrow fixed range around a certain reference position. A lean control mechanism is known.

[0008]

[Problems to be Solved by the Invention] However, the above-mentioned deviation control means displaces one of the belt suspension tension supporting members that influences the deviation direction of the belt under a certain fixed condition, and in the initial state, a certain degree of component accuracy is required. Alternatively, the initial adjustment can guarantee the reciprocating movement of the belt, but when some external condition is applied, even if the above member is displaced, the belt does not deviate in the predetermined direction and the displacement increases. Even if the belt can run in the reverse direction or, on the contrary, it can be moved in the desired direction as a result of increased control displacement, the belt will move closer at a rapid speed, causing skewed recording material and wrinkles on the belt. As a result, stable belt running cannot be realized.

As the above-mentioned external conditions, the influence of heat is the most important, and it is not necessary to consider an extreme temperature difference in general belt conveyance, but in the case of the heat fixing device of the above example, In the temperature rising state, the temperature of each component rises to about 150 ° C to 200 ° C. Due to this temperature rise, the coefficient of friction of the conveying means and the surface of the heating body changes (generally becomes smaller), so the initial reciprocating conditions toward the belt may be broken. In addition, there is a temperature distribution in the heating element itself, the size of the recording material to be fed, and the temperature rise in the non-sheet passing area based on one-sided reference. If there is, the transportation means also has a temperature gradient,
A difference in thermal expansion occurs in the longitudinal direction, and as a result, the belt shift changes due to the difference in conveyance speed. Further, due to wear, the friction coefficient changes due to abrasion of the inner surface of the belt, the conveying means, and the surface of the heating body, which also causes the deviation condition to change. Further, in the belt fixing method, since the belt is conveyed while rubbing the fixedly supported heating body, the inner surface of the belt may be lubricated with fluorine-based heat-resistant grease for the purpose of preventing vibration at the rubbing portion and reducing torque. In this case, since the viscosity of the grease has temperature dependency and the grease application state changes between the initial stage and the end stage, the shift condition of the belt also changes, which affects the above-mentioned shift control. It will be.

[0010]. In addition, if the belt position control range is limited to an extremely narrow range in order to grasp the above situation and perform appropriate control, small size paper with a constant width (can be passed through the fixing device) When a recording material having a width smaller than that of the maximum width size) is fed, a problem occurs. That is, since the belt is a thin film, the damage due to the edge of the small size paper cannot be ignored. Depending on the type of paper, the structure may be very susceptible to damage to the belt due to the fact that paper dust and filler are likely to come out to the edge of small size paper and the roughness of the edge due to cutting remains. If the belt position stays within the extremely narrow deviation control range, the damage caused by the edge of the paper is concentrated, so the belt coat is peeled off and other damage occurs on the belt. Had occurred.

Attempts have also been made to reciprocate the belt within a relatively large deviation control range area in order to avoid the damage, but this time, deviation of the belt has occurred.

In order to overcome the two conflicting events,
It has been considered that a plurality of reference points are set relatively finely and control is performed while sequentially changing the points. However, although the idea itself is good, when it comes to an actual method, for example, it is very difficult for a microcomputer to generate a random number, and it is difficult to control the tendency with a random number. There is also a method in which the reference points are changed step by step, but the above damage only diminishes step by step. In addition, there is a fear that the problem of biasing may occur depending on the setting method.

Therefore, the present invention has an object to solve the above problems.

[0014]

SUMMARY OF THE INVENTION The present invention is a belt deviation control device, a fixing device, and an image forming apparatus having the following features.

(1) A deviation control means for controlling deviation in a direction orthogonal to the moving direction of the belt so that the position of the belt driven and moved in a direction orthogonal to the moving direction is aligned with a reference point, and the deviation control means. With a state quantity detecting means for detecting or inputting a state quantity related to the deviation control by the, and a rule relating the relationship between the state quantity and the operation amount when the deviation control means performs the deviation control as a non-linear rule. A belt deviation control device comprising: a means and a calculation means for calculating the manipulated variable in accordance with the rule output from the rule means.

(2) A deviation control means for controlling a deviation in a direction orthogonal to the moving direction of the belt so that the position of the belt driven and moved in the direction orthogonal to the moving direction is aligned with the reference point, and the belt is the above-mentioned. When the reference point is reached, based on the reference point, a calculating means for calculating a new reference point based on the rule of the non-linear function, and the deviation control means, based on the new reference point, again A belt deviation control device characterized by performing the deviation control.

(3) A fixing device having a belt which is driven to move, a recording material to be image-fixed is brought into close contact with the belt and is conveyed together with the belt, and the image is fixed in the contact conveyance process. A shift control means for controlling the shift in the direction orthogonal to the moving direction of the belt so that the position of the driven belt in the direction orthogonal to the moving direction is aligned with the reference point, and a state related to the shift control by the shift controlling means. A state quantity detecting means for detecting or inputting an amount; a rule means for relating the relationship between the state quantity and an operation amount when performing the deviation control by the deviation control means as a non-linear rule; and the rule means A fixing device, comprising: a calculating unit that calculates the operation amount according to the output rule.

(4) A fixing device having a belt which is moved and driven, and a recording material to be image-fixed is brought into close contact with the belt to be conveyed together with the belt, and the image is fixed in the contact conveyance process. Deflection control means for controlling the deviation in the direction orthogonal to the moving direction of the belt so that the position in the direction orthogonal to the moving direction of the driven belt is aligned with the reference point, and when the belt reaches the reference point. And a calculating means for calculating a new reference point based on the rule of the non-linear function based on the reference point, wherein the deviation control means performs the deviation control again based on the new reference point. Characterizing fixing device.

(5) An image forming apparatus having an image forming means for forming an unfixed image corresponding to target image information on a recording material and a fixing device for fixing the unfixed image formed on the recording material. The fixing device is a fixing device that has a belt that is driven to move, and a recording material to be image-fixed is brought into close contact with the belt to be conveyed together with the belt, and the image is fixed in the contact conveyance process. A shift control means for controlling the shift in the direction orthogonal to the moving direction of the belt so that the position of the driven belt in the direction orthogonal to the moving direction is aligned with the reference point, and a state related to the shift control by the shift controlling means. A state quantity detecting means for detecting or inputting a quantity, a rule hand for relating the relationship between the state quantity and the operation quantity when the deviation control means performs the deviation control as a non-linear rule. When the image forming apparatus characterized by comprising a calculating means for calculating the manipulated variable in accordance with rules that are outputted from the convention means.

(6) An image forming apparatus having an image forming means for forming an unfixed image corresponding to desired image information on a recording material and a fixing device for fixing the unfixed image formed on the recording material. The fixing device is a fixing device that has a belt that is driven to move, and a recording material to be image-fixed is brought into close contact with the belt to be conveyed together with the belt, and the image is fixed in the contact conveyance process. Deflection control means for controlling the deviation in the direction orthogonal to the moving direction of the belt so that the position in the direction orthogonal to the moving direction of the driven belt is aligned with the reference point, and when the belt reaches the reference point. And a calculating unit that calculates a new reference point based on the rule of the non-linear function based on the reference point, and the deviation control unit performs the deviation control again based on the new reference point. Image forming apparatus characterized by.

[0021]

[Action]

(A) That is, according to the present invention, the state quantity detecting means (such as the photointerrupter 4 of the embodiment described later or the position detecting system (FIG. 3)), the rule means (the chaos rule means (FIG. 9), etc.), the calculation By providing a means (such as a CPU), the deviation control operation amount by the deviation control means is related to the deviation control by the deviation control means, specifically, mainly the temperature state of the apparatus and other non-sheet passing portion temperature rises. The state of the apparatus is properly calibrated according to the current state quantity such as the degree of progress of durability of the apparatus, and the belt deviation control means executes the belt deviation control with the calibrated operation amount. Regardless of changes, it is possible to always maintain an appropriate belt deviation control operation without causing control injustice, and always realize stable belt conveyance and running.

(B) Further, according to the present invention, when the deviation-controlled belt reaches the reference point as described above, a new reference point is calculated based on the reference point based on the rule of the non-linear function, The deviation control means performs the deviation control again based on this new reference point, that is, the target position of the belt deviation control is set by using the chaotic method, whereby the target position of the belt deviation control is set to the belt position. It can be easily and appropriately changed without causing offsetting. For example, in the above-mentioned belt fixing type fixing device, even when a small size paper is flowed, the edge of the paper corresponds to almost the same part of the belt. It is possible to prevent the belt region from being locally damaged and improve the durability of the device.

[0023]

【Example】

<Example 1> (A) Example of image forming apparatus (Fig. 1) Fig. 1 is a schematic configuration diagram of an example of an image forming apparatus. The image forming apparatus 1 of this example is a fixed original-moving optical system transfer type electrophotographic copying machine.

Reference numeral 51 denotes a fixed original platen glass disposed on the upper surface of the copying machine. The original 52 to be copied is placed on the original platen glass 51 with the image surface to be copied facing downward and a predetermined placement reference. Then, the original pressure plate 53 is placed thereon to set the original.

Based on the copy start signal, the electrophotographic photosensitive drum 60 is rotationally driven in the clockwise direction indicated by the arrow at a predetermined peripheral speed (process speed), and the primary charger 61 causes the peripheral surface of the drum to have a predetermined polarity and potential. Is uniformly charged. Further, the original illumination lamp 54 of the moving optical system and the moving first
The mirror 55 moves forward along the lower surface of the platen glass 51 from the left side of the glass to the right side at a predetermined speed V, and the moving second and third mirrors 56 and 57 move along the lower surface of the platen glass 51 to the left side of the glass. From the left side to the right side at a predetermined speed V / 2, the downward image surface of the set original on the original table glass 51 is optically scanned from the left side to the right side, and the original surface scanning light is an imaging lens. Slit imaging exposure L on the surface of the rotary photoconductor drum 60, which is subjected to primary charging, via the fixed mirror 59 and the fixed mirror 59.
As a result, an electrostatic latent image corresponding to the original image is formed on the surface of the rotating photoconductor drum 60.

The electrostatic latent image is developed as a toner image by the developing device 62, and the toner image is transferred onto a transfer material P as a recording material at a transfer portion which is a pressure contact nip portion between the photosensitive drum 60 and the transfer roller 63. Is transcribed to. The transfer material P is separated and fed from the paper feed cassette 64 by the paper feed roller 65, and is conveyed and introduced into the transfer portion at a predetermined timing through the sheet path 66.

The transfer material P that has passed through the transfer portion is separated from the surface of the rotary photosensitive drum 60 and is conveyed and introduced into the fixing device 2 by the conveying device 69. The transfer material P is subjected to a fixing process of the transferred unfixed toner image, and is made as a copy. The sheet is discharged to the sheet discharge tray 70 outside the machine.

The surface of the photoconductor drum 60 which has passed through the transfer section and after the transfer material is separated is subjected to removal of adhering contaminants such as transfer residual toner by a cleaning device 67, and static elimination exposure by an eraser lamp 68. It is repeatedly used for image formation.

(B) Fixing Device 2 (FIG. 2) The fixing device 2 of this embodiment is a belt (film) fixing type heat fixing device using a thin film belt (fixing film) which is rotationally driven. FIG. 2 is a perspective view of a main part.

Reference numeral 6 is an endless fixing belt. It is composed of a heat-resistant base layer belt made of polyimide or the like, and a surface layer covering the outer peripheral surface thereof. The surface layer is a releasing layer that prevents toner from sticking to the outer peripheral surface of the belt 6, and is a fluororesin layer or the like. The total thickness of the belt 6 is generally 100
The thin film has a thickness of less than or equal to μm, preferably less than 40 μm.

7. 8, 9 are drive rollers, tension rollers (driven rollers), which are arranged substantially parallel to each other.
It is a heating body, and the above-mentioned endless belt 6 is suspended and supported between these three members 7, 8 and 9. Reference numeral 3 denotes a pressure roller in which the belt 6 is sandwiched and pressed against the lower surface of the heating body 9 to form the fixing nip portion N.

The drive roller 7 is a roller for driving the belt 6 to rotate. The shafts of both ends of the drive roller 7 are freely rotatably supported and fixedly supported, and the drive force of the main motor 30 of the copying machine is not shown. It is received by way of and is driven to rotate clockwise in the direction of the arrow in the drawing.

The tension roller 8 is biased by a biasing member in such a direction that the belt 6 is always tensioned. The tension roller 8 is configured so that the inclination of the shaft can be changed by the displacement means 80 as described later.

The heating element 9 is a fixed low heat capacity linear heating element which is fixedly mounted on a stay (not shown). For example, it is a ceramic heater, and the temperature is controlled to a predetermined fixing temperature by rapidly raising the temperature by energizing an energization heating resistor pattern of the heater by an energization system (not shown). As a power control method, for example, a phase control method is used.

The belt 6 is driven by the rotation of the driving roller 7 by frictional force between the outer surface of the driving roller 7 and the inner surface of the belt.
It is rotationally driven in the clockwise direction a indicated by the upward arrow. The pressure roller 3 that is in pressure contact with the heating body 9 with the belt 6 interposed therebetween is driven to rotate as the belt 6 rotates. At the fixing nip portion N, the belt 6 rotates while sliding its inner surface in close contact with the lower surface of the heating body 9.

Thus, in the state where the belt 6 is rotationally driven and the heating body 9 is heated by energization, the image forming means forms an unfixed toner image corresponding to the target image information, and recording is performed. The transfer material P as a material is conveyed and introduced between the belt 6 of the fixing nip portion N and the pressure roller 3 with the toner image surface on the belt 6 side, and is brought into close contact with the outer surface of the belt to move the fixing nip portion N to the belt 6. Carry and pass through. In the process of passing through the fixing nip portion, the heat of the heating body 9 is applied to the belt 6
The unfixed toner image is applied to the transfer material P via the toner and is heat-fixed on the surface of the transfer material P. The transfer material P that has passed through the fixing nip portion N is separated from the surface of the belt 6 and discharged as a copy.

(C) Belt deviation control means a) Belt deviation position detection means (FIGS. 3 to 5) As described above, the belt 6 is a driving roller 7 and a tension roller 8 that are suspension supporting members in the course of rotation.
It is easy to shift to the back side or the front side of the belt width direction (direction orthogonal to the belt rotation direction) b along the length of the heating element 9 and to be displaced from the reference position. The belt deviation position detecting means is a degree of position deviation from the reference position of the belt 6 to the back side or the front side in the belt width direction b.
Is to detect.

The following is the structure of the belt deviation position detecting means in the apparatus of this embodiment.

The belt 6 has a back side edge portion 6a in the belt width direction b which is cut in a mountain cutting pattern as shown in the belt development view of FIG.

The belt edge 6a on the back side of this mountain cutting pattern
A photo interrupter 4 for detecting the shift position of the belt 6 is fixedly disposed on the side. In the present embodiment, the photo interrupter 4 is used which outputs a low level L when the light receiving section detects the light from the light emitting section and outputs a high level H when the light from the light emitting section is blocked.

Since the back side edge portion 6a of the belt 6 on the photo interrupter 4 side is cut in the mountain cutting pattern, the output signal Sig. Becomes as shown in FIG. That is, the photo interrupter 4 outputs a high level H when the light from the light emitting portion in the photo interrupter 4 is shielded by the belt back side edge portion 6a in the mountain cutting pattern in one rotation process of the belt 6. It outputs a low level L when it is not blocked.

When the belt 6 is rotating at a predetermined reference position in the belt width direction and there is no deviation, the photo interrupter 4 is rotated in one rotation process of the belt 6 as shown in FIG. The time ratio between the high level H and the low level L of the signal output from is approximately 1: 1,
The duty ratio of the output from the photo interrupter 6 is always constant. However, when the belt 6 moves toward the rear side or the front side in the width direction b, the duty ratio of the output of the photo interrupter 6 corresponds to that side, as shown in (b) or (c) of FIG. Change to.

Specifically, as the belt 6 moves toward the inner side in the width direction b (direction closer to the photo interrupter 6 side), the high level output time τ from the photo interrupter 6 becomes longer, and conversely, the belt The time τ of the high level becomes shorter as 6 moves closer to the front side in the width direction b (the direction away from the photo interrupter 6). Based on this signal, the deviation position of the belt 6 in the width direction b can be detected. The relationship between the high level output time τ from the photo interrupter 4 and the shift position of the belt 6 in the width direction b is quantitatively as shown in FIG. It is possible to know the belt deviation position from this graph. Actually, the signal Sig. Is input to the control circuit (microcomputer) 100, and the current position of the belt 6 is detected from the relationship shown in FIG.

B) Displacement means for the tension roller 8 (FIG. 6) The belt 6 that has moved toward the rear side or the front side in the belt width direction b is a member 7, 8 ...
By changing the inclination of the axis of one of the shafts 9, the belt 6 that has moved closer can be artificially returned and moved in the reference position direction.

In this embodiment, the belt deviation is controlled by changing the inclination of the axis of the tension roller 8 based on the belt deviation position information detected by the detecting means 6a.

The following is the structure of the displacement means of the tension roller 8 in this embodiment.

The tension roller 8 has a shaft portion 8 on the back side thereof.
As shown in FIG. 6, the displacement mechanism 80 causes the displacement mechanism 80 to vertically raise and lower the displacement c or lower the displacement d so that the tension roller 9 is moved relative to the axes of the driving roller 7 and the heating body 9. The inclination of the axis can be changed.

In the above displacement mechanism 80, 5 is a drive motor such as a stepping motor, the output shaft of which is coaxially connected to the lower end of a vertically oriented screw shaft 82 via a coupling 81. 83 is the screw shaft 8
2 upper end bearing. Reference numeral 84 denotes a screw receiver (female screw member) screwed onto the screw shaft 82. Reference numeral 85 denotes a downwardly extending bifurcated arm provided integrally with the movable bearing 86 on the rear end side of the tension roller 8. This forked arm 85
The screw receiver 84 is fixedly held between the arms. 87 is a biasing spring that biases the tension roller 8 in a direction in which the belt 6 is always tensioned.

When the motor 5 is driven in the normal direction, the screw shaft 82 rotates in the normal direction, whereby the screw receiver 84 moves upward along the screw shaft 82. That is, the forked arm 85 and the bearing 86 move upward, and the rear end side of the tension roller 8 is lifted and displaced c.

Conversely, when the motor 5 is driven in reverse,
The screw shaft 82 rotates in the reverse direction, whereby the screw receiver 84 moves downward along the screw shaft 82. That is, the forked arm 85 and the bearing 86 move downward, and the rear end side of the tension roller 8 is lowered and displaced.

Screw shaft 82 and screw receiver 84
If the screw pitch of p is p, the vertical displacement of the tension roller 8 on the back end side can be varied by the amount of forward or reverse rotation of the screw shaft 82, and the tension can be changed by one forward or reverse rotation of the screw shaft 82. The rear end side of the roller 8 is pmm
The displacement c / d can be performed upward or downward.

When the back end side of the tension roller 8 is displaced upwards c, the rotating belt 6 is displaced rearward in the belt width direction b, and when it is displaced downward d, the belt 6 is artificially moved toward the front side of the belt. It can be moved.

C) Control (FIGS. 7 to 10) A specific method of the above belt deviation control will be described based on the flow of FIG. The control circuit 100 (FIG. 2) controls the motor 5 of the displacement mechanism 80 of the tension roller 8 in the normal rotation or the reverse rotation based on the belt deviation position information detected / input by the belt deviation position detecting means 6a.

First, the current offset position of the belt 6 is obtained by the above-mentioned τ of the signal from the photo interrupter 4,
Store (step 1).

Next, when the deviation position of the belt 6 is obtained,
It is judged whether or not the position is farther from the reference position than the previously detected deviation position (step 2). If it is far, the tension roller 8 is moved in the direction of bringing the belt closer to the reference position.
The motor 5 is rotated so that is displaced (step 3).

A method of determining the reference position will be described.
FIG. 8 shows a recursive function that determines the reference position. ΔS is
The value is smaller than ΔL (FIG. 3) and indicates the limit of change in the reference position. A recursive function is a function represented by x = f (x), which has the same domain and range and performs mapping onto itself. Further, f (x) is a non-linear function that is bent at the center as can be seen from FIG. 8 and is a source for generating a sequence of chaos. The actual method will be described.

First, the initial reference position is set to a position other than the center position, ± ΔS, and ± 1 / 2ΔS by some method ((1) in FIG. 9A). From there, a new reference position (2) is calculated based on the function.
Again, in this manner, (3) is calculated as shown in (b) of FIG. This is done every time the belt reaches the reference position.

According to the flowchart of FIG. 10, first,
If the reference position has not been determined, the reference position is determined (step 1). Always monitor whether the previous reference position has been reached (step 2). If it has reached the reference position, a new reference position is set based on the above (step 3). The motor 5 is driven so that the belt approaches in that direction (step 4).

As described above, in this embodiment, when the deviation-controlled belt reaches the reference point, a new reference point is calculated based on the reference point based on the rule of the non-linear function, and the deviation control means The deviation control is performed again based on the new reference point, that is, the target position of the belt deviation control is set by using the chaotic method, and the target position of the belt deviation control causes the deviation of the belt. In the fixing device of the belt fixing system of the present embodiment, even when a small size paper is flowed, the edge of the paper corresponds to almost the same part of the belt and the belt part corresponds to almost the same part. Local damage is prevented and the durability of the device can be improved.

<Embodiment 2> (FIG. 11) In the present invention, for example, it is conceivable to perform the same control as in Embodiment 1 by using a recursive function as shown in FIG. It is also possible to examine the curve of f (x) through experiments and optimize f (x) so as to obtain the optimum target setting.

The above embodiment is an image heating fixing apparatus of the belt fixing type or an image forming apparatus equipped with the fixing apparatus. However, the present invention is not limited to this, and a belt in an apparatus including a belt driven to move. Widely effective as a deviation control means. Needless to say, the belt deviation position detecting means and the deviation control means are not limited to those of the embodiment.

[0062]

As described above, according to the present invention, a proper belt is always maintained without causing control irregularity irrespective of a change in the state quantity such as the device temperature that affects the belt deviation control, that is, a change in the external condition. The deviation control operation can be maintained, and stable belt conveyance and running can always be realized.

Further, according to the present invention, the target position of the belt deviation control is set by using the chaotic method, so that the target position of the belt deviation control can be easily and appropriately changed without causing the deviation of the belt. For example, in the case of a belt fixing type fixing device, even when a small size paper is flowed, the edge of the paper is prevented from locally damaging the belt part corresponding to almost the same part of the belt. It becomes possible to improve durability.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus.

FIG. 2 is a perspective view of a schematic configuration of a belt fixing type image heating fixing device.

FIG. 3 is a developed plan view of the back end of the belt.

FIG. 4 is an aspect diagram of a signal output from a photo interrupter.

FIG. 5 is a diagram showing a relationship between a signal output from a photo interrupter and a belt offset position.

FIG. 6 is a side view of a tension roller displacement means section.

FIG. 7 is a control flow chart when the belt is aligned with the reference position.

FIG. 8 is a nonlinear recursive function for calculating a reference position.

FIG. 9 is an explanatory diagram of a specific method of calculating a reference position.

FIG. 10 is a flow chart for calculating a reference position.

FIG. 11 is a non-linear recursive function used in Example 2.

[Explanation of symbols]

 2 Belt fixing type image heating fixing device 3 Pressure roller 4 Photo interrupter 5 Tension roller displacement motor 6 Fixing belt 7 Drive roller 8 Tension roller 9 Heating element 80 Tension roller displacement mechanism 100 Control circuit (microcomputer)

Claims (6)

[Claims] 1. A deviation control means for controlling a deviation in a direction orthogonal to a moving direction of a belt so that a position in a direction orthogonal to a moving direction of a belt which is driven to move is aligned with a reference point, and the deviation controlling means. A state quantity detecting means for detecting or inputting a state quantity related to the deviation control, and a rule means for associating the relationship between the state quantity and the operation amount when the deviation control means performs the deviation control as a non-linear rule. And a calculation means for calculating the manipulated variable according to the rule output from the regulation means. 2. A deviation control means for controlling a deviation in a direction orthogonal to the moving direction of the belt so that a position in a direction orthogonal to the moving direction of the driven belt is aligned with a reference point, and the belt is the reference. When a point is reached, a calculation means for calculating a new reference point based on the rule of the non-linear function based on the reference point, and the deviation control means, based on the new reference point, again A belt deviation control device characterized by performing deviation control. 3. A fixing device having a belt which is moved and driven, and a recording material to be image-fixed is brought into close contact with the belt to be conveyed together with the belt, and the image is fixed in the contact conveyance process. A deviation control means for controlling the deviation in the direction orthogonal to the movement direction of the belt so that the position in the direction orthogonal to the movement direction of the belt is aligned with the reference point, and the state quantity related to the deviation control by the deviation control means. State quantity detecting means for detecting or inputting, and a regulation means for relating the relation between the state quantity and the operation amount when performing the deviation control by the deviation control means as a non-linear rule, and an output from the rule means And a calculating unit that calculates the operation amount according to the established rule. 4. A fixing device having a belt that is moved and driven, and a recording material to be image-fixed is brought into close contact with the belt to be conveyed together with the belt, and the image is fixed in the contact conveyance process. The deviation control means for controlling the deviation in the direction orthogonal to the moving direction of the belt so as to match the position in the direction orthogonal to the moving direction of the belt with the reference point, and when the belt reaches the reference point, Calculating means for calculating a new reference point based on the rule of the non-linear function based on the reference point, and the deviation control means performs the deviation control again based on the new reference point. And fixing device. 5. An image forming apparatus comprising: an image forming means for forming an unfixed image corresponding to target image information on a recording material; and a fixing device for fixing the unfixed image formed on the recording material, The fixing device is a fixing device that has a belt that is moved and driven, and a recording material to be image-fixed is brought into close contact with the belt to be conveyed together with the belt, and the image is fixed in the contact conveyance process. A deviation control means for controlling the deviation in the direction orthogonal to the movement direction of the belt so that the position in the direction orthogonal to the movement direction of the belt is aligned with the reference point, and the state quantity related to the deviation control by the deviation control means. A state quantity detecting means for detecting or inputting, and a rule means for relating the relationship between the state quantity and the operation amount when the deviation control means performs the deviation control as a non-linear rule. An image forming apparatus characterized by comprising a calculating means for calculating the manipulated variable in accordance with rules that are outputted from the convention means. 6. An image forming apparatus comprising: an image forming unit that forms an unfixed image corresponding to target image information on a recording material; and a fixing device that fixes the unfixed image formed on the recording material. The fixing device is a fixing device that has a belt that is moved and driven, and a recording material to be image-fixed is brought into close contact with the belt to be conveyed together with the belt, and the image is fixed in the contact conveyance process. The deviation control means for controlling the deviation in the direction orthogonal to the moving direction of the belt so as to match the position in the direction orthogonal to the moving direction of the belt with the reference point, and when the belt reaches the reference point, Calculating means for calculating a new reference point based on the rule of the non-linear function based on the reference point, and the deviation control means performs the deviation control again based on the new reference point. An image forming apparatus comprising and.