JP2881890B2 - Fixing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device having a film that moves in contact with a recording material bearing an unfixed image.

(Prior Art) For convenience, a description will be given of an example of a fixing device that performs image fixing using a rotating endless film in an image forming apparatus such as a copying machine or a printer.

Various types and configurations of fixing devices for image forming apparatuses are known and are in practical use. Recently, a heating device (film heating method) including a fixedly supported heating element, a film in contact with the heating element, and a heating member configured to press the recording material against the heating element via the film has been devised. .

An apparatus and the like disclosed in Japanese Patent Application Laid-Open No. 63-313182 according to the applicant's earlier proposal belong to this, and the recording material is not fixed through a thin heat-resistant film (sheet) that is pressed against a fixed heating element. Apply thermal energy to the toner image to soften and melt it,
Separate the film and recording material, or allow the toner to cool
A heating means / apparatus based on separating a recording material from a film after solidification.

This film heating type fixing device is a heat roller type fixing device.
Compared with other thermal fixing devices such as hot plate method, flash fixing method and oven fixing method, a linear heating element with low heat capacity can be used, thus saving power and shortening wait time (quick start property). Since the fixing point and the separation point can be set separately, offset is prevented, and various other disadvantages of other system devices can be solved.

The film may be of an endless type, and may be configured so as to be rotated and driven to repeatedly use for fixing, or may be configured to use an end-rolled film that is fed out and run for fixing.

In a fixing device using an endless type film,
Film misalignment during film rotation (deviation)
Need to be prevented. Factors of this displacement include the parallelism and torsion of at least two endless film hanging and stretching members such as rollers that stretch and stretch the endless film, but there is a limit to improving their accuracy. It is very difficult to prevent the film from shifting only by improving the accuracy.

Therefore, as a deviation control means of the endless film, the shape of at least one of the rollers in which the endless film is stretched is formed into a crown shape,
Alternatively, flanges are provided at both ends of the roller to control the deviation of the endless film.

(Problems to be Solved by the Invention) However, in such a film deviation regulating means, when a heat-resistant sheet having a thin film thickness of less than 100 μm is used, even if a crown roller or a flanged roller is used, an endless Since the heat-resistant sheet as a film has no elasticity and is thin, wrinkles and the like are generated in the heat-resistant sheet, and it is difficult to control the deviation.

By displacing the roller axis of at least one of the members in which the endless film is stretched, the parallelism with other members is changed so that the direction of the endless film can be switched, and at the same time, By providing a sensor for detecting the position of the endless film and performing the shift control, the shift can be regulated.

However, in this film shift control mechanism,
At the start of the shift control immediately after the power is turned on, the control is performed in a predetermined shift direction as an initial setting.If the speed difference is large depending on the shift direction, the initial film position is detected from the start of the control and the actual shift control is performed. When the endless film is shifted to either end before the start of the fixing, there is a disadvantage that not only the endless film is damaged but also the fixing device is damaged. Was. To this end, there is a disadvantage that the tension adjustment of the endless film must be performed with high accuracy in order to minimize the speed difference due to the deviation direction.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-described problems when such a film shift control mechanism is adopted.

(Means for Solving the Problems) According to the present invention, in a fixing device having a film that moves together with a recording material bearing an unfixed image, the deviation of the film in a direction perpendicular to the direction of movement of the film is controlled. A shift control unit; and a storage unit for storing a shift direction of the film by the shift control unit. When the power supply to the apparatus is turned on, the shift control unit shifts the film based on the storage content of the storage unit. Is a fixing device.

(Operation) That is, with the above-described apparatus configuration, even in a case such as immediately after power-on, it is possible to set the shift control direction up to the start of the shift control simultaneously with the start of the shift control.

This allows the endless film to move to either end if the speed difference due to the shift direction is large during the shift control disabled state from the start of the control to the detection of the initial film position until the actual shift control becomes possible. To prevent damage, and there is an effect that reliable shift control can be performed.

Of course, this makes it possible to prevent damage to the fixing device itself as in the above-described example, and at the same time, it is possible to control the deviation even if the speed difference due to the deviation direction of the endless film is large, so that the tension adjustment of the endless film can be performed. There is also an effect that accuracy is not required and design margin is increased.

(Embodiment) <Embodiment 1> Fig. 1 is a plan view of an example of an endless film fixing device to which a film shift control device according to the present invention is applied, Fig. 2 is a side view, and Fig. 3 is a side view. 1 shows a schematic configuration of an example of an image forming apparatus incorporating the fixing device.

(A) Configuration of Image Forming Apparatus The image forming apparatus of the example shown in FIG. 3 is an electrophotographic copying machine of a document table reciprocating type, a rotating drum type, and a transfer type. The configuration, image forming process and the like of this copying machine are publicly known. Since it belongs, only a brief explanation.

Reference numeral 52 denotes a reciprocating original platen glass disposed on the upper plate 51 of the copier housing 50, which is reciprocally driven in the left and right direction by a drive mechanism (not shown).

The original 53 is placed at a predetermined position on the upper surface of the original platen glass 52 with the image surface to be copied facing downward, and is held down by the original pressing plate 54 and set.

The downward image surface of the set document 53 undergoes slit illumination scanning by sequentially passing through the illuminating section 55 during the forward or backward movement of the document table glass 52. Reference numeral 56 denotes an illumination light source.

The downward illumination light of the original surface of the slit illumination light is sequentially imaged and exposed by an imaging lens (short focus imaging element array) 57 on the surface of a photosensitive drum 58 which rotates synchronously with the scanning of the original image.

The photosensitive drum 58 undergoes a positive or negative uniform charging process by the discharger 59, and then undergoes the above-mentioned image forming exposure, whereby an electrostatic latent image corresponding to the document image is sequentially formed on the drum peripheral surface. To go.

Next, the surface of the photosensitive drum 58 on which the latent image is formed is
It sequentially passes through 60 positions and undergoes sequential development of latent images.

The developed image on the surface of the photosensitive drum 58 reaches the transfer discharger 61 position.

On the other hand, the transfer material P is supplied from the transfer material cassette 62 to a paper feed roller.
One sheet is fed into the copying machine at 63, and the leading end is received by the nip portion of the pair of registration rollers 64 which is in a rotation stopped state at that time. Here, the rotation of the registration roller pair 64 is started at a predetermined timing synchronized with the rotation of the photosensitive drum 58, whereby the transfer material P is guided by the guide member and fed toward the photosensitive drum 58, and Drum 58
The developed image on the surface of the photosensitive drum 58 is sequentially transferred to the transfer material P introduced into the transfer portion between the transfer member 61 and the transfer discharger 61.

The transfer material P to which the image transfer has been performed is sequentially separated from the surface of the photosensitive drum 58 by a separation unit (not shown),
The image is fixed to an image and is discharged to a discharge tray 67 outside the apparatus by a discharge roller 66 as an image formed product (copy).

The surface of the photosensitive drum 58 after the image transfer is cleaned by the cleaning device 68, and is repeatedly provided for image formation.

(B) Fixing device In FIGS. 1 and 2, reference numerals 13 and 12 denote a pair of left and right endless film driving rollers and a driven roller which also serves as a tension roller.
An endless film stretched and suspended between 12, and the drive roller 13 is rotated at a predetermined peripheral speed in the clockwise direction of arrow a by being rotationally driven in the clockwise direction as indicated by the arrow by the drive system including the drive motor 27. It is driven to move.

Film 11 is a heat resistant film having a total thickness of 100μ, more preferably less than 40μ. In this embodiment, the thickness is 20μ.
Of polyimide, polyetherimide, PES, PFA, etc. as a base film and a release layer of PTFE etc. on the image contact surface
It is an endless film coated about 10μ.

Reference numeral 14 denotes a heating element fixedly disposed (fixed and supported by a fixing device) on the inner surface side of the descending film portion of the endless film 11 described above. This heating element is a low-heat-capacity linear heating element (hereinafter, referred to as a heater) having a length in the direction intersecting the surface movement direction of the film 11, that is, the film width direction, and generates heat when energized.

Reference numeral 15 denotes a pressure roller having a rubber elastic layer having good releasability such as silicon rubber, and a film portion on the lower side of the endless film 11 is sandwiched between the pressure roller and the heater 14, for example, by urging means (not shown). It is brought into pressure contact with a contact pressure of 4 to 5 kg in total, and rotates in the film moving direction in the forward direction at the same peripheral speed as the film speed as the film moves.

Unfixed toner image t (heat-fusible toner) conveyed from transfer unit 61 (FIG. 3) to fixing device 1 by conveyance device 65
Transfer material P carrying on its upper surface enters between the film 11 and the pressure roller 15 of the pressure contact portion (fixing nip portion) N formed by the heater 14 and the pressure roller 15 with the endless film 11 interposed therebetween. The unfixed image surface adheres to the surface of the film 11 in the surface moving state in the same direction at substantially the same speed as the transfer speed of the transfer material P, and passes through the fixing nip N while receiving the narrow pressure while overlapping with the film 11. Go. In this process, the toner image carrying surface of the transfer material P is heated by receiving the heat of the heater 14 via the film 11, and the toner image t is completely softened and melted at least in the surface layer portion, and is thermally fixed to the transfer material P surface. .

The transfer material P that has passed through the fixing nip portion N is separated from the surface of the film 11 at the curvature of the film 11 along the roller 13 when passing through the position of the film drive roller 13.

(C) Film deviation control mechanism Drive roller 13 and driven roller of endless film 11
As shown in FIG. 1, reference numeral 12 denotes a bearing arranged between a front side plate 19 and a rear side plate 18 of the fixing device 1. 21 ・ 20
Reference numeral denotes a bearing on the front end side and a bearing on the rear end side of the driven roller 12.

Here, unless the accuracy of the parallelism (X-axis direction, Y-axis direction, Z-axis direction) of the driving roller 13, the driven roller 12, the heater 14, and the pressing roller 15 is set to ± 0, the driving roller 13 is driven and the film is formed. When rotating 11 in the direction of the arrow,
The film 11 is initially formed by the positional relationship (dispersion in the X, Y, and Z axes) of the rollers 13 and 12 and the heater 14 on which the film 11 is suspended and stretched, as shown by the solid line in FIG. Is shifted to the right or left in the film width direction from the position (1), and the end of the film is rubbed against the side plate 18 or the side plate 19 and is damaged.

Therefore, in the present embodiment, the bearing 20 on the far end side of the driven roller 12 is supported by the side plate 18 with a degree of freedom of movement in the front and rear directions of arrows A and B. To move to the first position shown by the solid line and received by a stopper (not shown), and the plunger of the solenoid 23 is connected so that the energization of the solenoid turns on the bearing.
20 is pulled in the retreating direction B against the compression spring 22 so that 2
The position is displaced to the second position indicated by the chain line.

That is, the energization ON-OFF of the solenoid 23 causes the driven roller 12
The degree of parallelism with respect to the drive roller 13 and the heater 14 can be varied.

In this example, when the solenoid 23 is OFF and the bearing 20 is at the first position shown by the solid line, the rotating film 11 is
On the top of the rollers 12 and 14, the entire length of the rollers 13 and 12 moves toward the left side in the film width direction, that is, toward the far end side of the rollers 13 and 12. When the rotating film 11 is at the position, the rotating film 11 moves to the right in the film width direction, that is, toward the front ends of the rollers 13 and 12 in the opposite direction.

Reference numeral 16 denotes a photosensor for detecting the position of the shift of the film. Also, as shown in Fig.
The end 3 on the front side of 11 is masked as shown by hatching so as to block the light of the photo sensor 16 around the entire edge.

In the present embodiment, a photo interrupter is used for the photo sensor 16, but when a reflection type photo sensor is used here, the end portion 3 of the film 11 needs to be treated with a reflection member to reflect light. is there.

In the present embodiment, processing such as masking is performed on the film 11.
However, it is needless to say that it may be performed on the entire film.

Reference numeral 4 denotes a film edge cleaning member which constantly cleans the film edge so as to prevent erroneous reading when a reflection type sensor is used due to contamination of the film edge or the like. In the present embodiment, felt is used, but the type is not limited as long as it has a cleaning effect.

FIG. 4 shows the external shape of the film 11. This film is an endless belt as described above, and its diameter is φM. Also, as shown in the figure, one end (front end) of the film 11 is cut diagonally, and the length of the longest part is Lmax, and the length of the shortest part is Lmin. The dimension of the obliquely cut portion (oblique cut portion) is determined by Lmax-Lmin, and is set to ΔL (film oblique cut amount) here. The oblique cut portion is arranged on the front side of the main fixing device as shown in FIG. 1 so that the photosensor 16 detects the position of the film 11.

FIG. 5 is a detailed view of the positional relationship between the photo sensor 16 and the film 11. In this embodiment, a transmission type photo interrupter is used for the photo sensor 16, and the detection position is indicated by b. This means that the photo sensor 16 is turned on when the film 11 is on the back side of the position b, and turned off when the film 11 is on the front side of the position b. Also film 11
Is configured to be at the position of the detection position b.

That is, as the film 11 rotates in the direction of arrow a shown in FIG. 2, the photosensor 16 repeats ON / OFF, and the ratio of the ON / OFF cycle (the shift position) depends on the film position (deviation position). duty ratio) will be variable.

The film position shown in FIG. 5 represents a reference position where the center of the oblique cut portion of the film 11 is located at the detection position b of the photo sensor 16. FIG. 6 is a graph showing the relationship between the film position and the OFF time of the photosensor 16 around the reference position of the film.

As shown in FIG. 6, when the film 11 is at the reference position b, the OFF time of the photosensor 16 is c seconds, and
When 1 is not less than ΔL / 2 and closer to the reference position b, the OFF time of the photosensor 16 is 0 second.

Conversely, when the film 11 is located at the rear side of the reference position b by ΔL / 2 or more, the photo sensor 16 is kept off.

Here, the position of the film 11 turns off the photo sensor 16
The OFF time in the case immediately before the position where the film 11 continues to be kept is d seconds, which can be considered to be almost equivalent to the time required for the film 11 to make one round, and the OFF time c seconds at the reference position b is the center of the film oblique cut portion. Therefore, the time is approximately half of the OFF time d seconds.

(D) Film-Side Movement Control Circuit FIG. 7 is a schematic diagram of the electric control.

26 is a microcomputer whose input terminal IN1
Is connected to the photo sensor 16. A solenoid 23 is connected to the OUT1 terminal. The OUT2 terminal outputs a rotation control signal of the motor 27 that also drives the fixing device.

The + 5V power supply is connected to the VDD terminal, and the GND terminal is connected to the ground.

Although not shown, other input and output signal terminals of the copying machine using the present fixing device are provided, and a sequence program for the copying operation of the copying machine is programmed in the microcomputer 26. ROM and RAM
In addition, a non-volatile RAM, which retains its stored contents even when the power supply to the microcomputer 26 is cut off, is built in.

8 to 11 show flowcharts of a film shift control program of the fixing device.

This program is also programmed in the built-in ROM in the microcomputer 26 described above, and is called and executed by a main sequence program or the like at regular time intervals or as needed.

First, after the start, in step 1 (FIG. 8), it is determined whether or not the motor 27 is ON. If the motor 27 is ON, the process proceeds to step 2 and
If the motor 27 is off, return to step 1 and turn on the motor 27
You will have to wait until you do.

Next, in step 2, it is determined whether or not the film has been controlled so as to approach the front side.
This sets the content of a predetermined address in the nonvolatile RAM in the microcomputer 26 as a near side flag. When the state of the memory is 1, that is, when the memory has been controlled to the near side, the process proceeds to step 3. Then, the solenoid 23 is turned ON, the shift control is set to the near side, and the process proceeds to step S4. If the near side flag is 0 in step 2, the film is controlled so as to be shifted to the far side so that the process proceeds to step 4 as it is.

In step 4, it is determined whether or not the sensor 16 is OFF. If the sensor 16 is ON, the process proceeds to step 8 and turns OFF.
In the case of, go to step 5.

In step 5, the value of the error timer is reset to 0, measurement is started, and the process proceeds to step 6.

In step 6, it is determined whether or not the sensor 16 is ON. If not, the process proceeds to step 7.

In step 7, an error check routine is executed, and the process returns to step 6.

Here, the content of the error check routine will be described with reference to FIG. 10. First, in step S1, the motor 27 is turned on.
Is determined, and if it is ON, step S2
Then, if it is not ON, go to step 13 (FIG. 9).

In step S2, it is determined whether or not the error timer value is greater than d seconds. If the error timer value is less than d seconds, the process proceeds to the exit of this routine. If the error timer value is greater than d seconds in step S2, the process proceeds to step S3.

In step S3, an error flag is set, and the routine goes to the exit of this routine.

Next, if the sensor 16 is ON in step 6, the process proceeds to step 8, resets the value of the error timer to 0, starts measurement, and proceeds to step 9.

In step 9, it is determined whether or not the sensor 16 is OFF. If the sensor 16 is not OFF, the process proceeds to step 10 to execute an error check routine, and returns to step 9, where the sensor 16 is turned off.
If is turned off, the process proceeds to step 11, resets the value of timer 1 to 0, starts measurement, and proceeds to step 12.
(Fig. 9).

In step 12, it is determined whether or not the motor 27 is ON. If the motor 27 is ON, the process proceeds to step 14.

In step 14, it is determined whether or not the sensor 16 is ON. If the sensor 16 is not ON, the process proceeds to step 15 to execute an error check routine and returns to step 14, and if it is ON, the process proceeds to step 16.

In step 16, a comparison is made as to whether or not the measured value of the timer 1 is smaller than d / 4 seconds. If the measured value is smaller than this, it can be determined that the film 11 is located on the near side. Is turned OFF, the direction of the approach of the film 11 is switched to the back side, the front flag is reset to 0, and the routine proceeds to step 20.

If the measured value of the timer 1 is not smaller than d / 4 seconds in step 16, the process proceeds to step 18.

In step 18, a comparison is made as to whether the value measured by the timer 1 is greater than 3d / 4 seconds. If not, the process proceeds to step 20, and if it is greater, it is determined that the film 11 is located on the back side. Therefore, the process proceeds to step 19, where the solenoid 23 is turned on to switch the approach direction of the film 11 to the near side, the near flag is set to 1, and the process proceeds to step 20.

In step 20, the value of the error timer is reset to 0 and measurement is started, and the process proceeds to step 21.

In step 21, it is determined whether or not the sensor 16 is OFF. If the sensor 16 is not OFF, the process proceeds to step 22, executes an error check routine, and returns to step 21.

If the sensor 16 is OFF in step 21, the process proceeds to step 23, where the value of the timer 1 is reset to 0, measurement is started, and the process returns to step 12.

If the motor 27 is OFF in step 12 described above, the process proceeds to step 13, first, the measurement of the timer 1 is stopped, the measured value is reset to 0, and then the solenoid 23 is turned off.
F then returns to step 1.

FIG. 11 shows a flowchart of a film abnormality processing program which is a part of the main program. Here, in step 24, it is determined whether or not the error flag is set. If the error flag is not set, the process proceeds to the exit and the next main sequence program is executed.

If the error flag has been set in step 24, the process proceeds to step 25 to turn off all outputs of all devices (copying device in this embodiment), and then proceeds to step 26 to display a film abnormality display. Step 26 is a permanent loop, so that the main program cannot be executed.

As described above, the endless film 11 of the present fixing device first controls the solenoid 23 in accordance with the contents of the non-volatile RAM which stores the shift direction which has been controlled up to that time from the time of rotation of the motor. Next, when the sensor 16 is ON when the motor is rotating, wait until it is turned OFF.
If 6 is OFF, wait until it turns ON, then wait until it turns OFF, and then output from the film position sensor 16 from ON.
Detects the timing of switching to OFF and ends the initial setting. Then, the position of the film 11 is detected only by measuring the OFF time of the sensor 16 until the sensor 16 switches from OFF to ON.

That is, since the control of the film 11 is disabled until the time when the OFF time of the first sensor 16 is measured, the control is performed in the direction in which the control has been performed up to that time, so that the control can be performed during the aforementioned control disabled state. This prevents the film from abnormally approaching either end. Then, after the sensor 16 switches from ON to OFF, it turns off.
The OFF time of the sensor 16 until it is switched from ON to ON is measured, and the film position is controlled so as to be within a predetermined control range.

In this embodiment, a transmission type photo sensor is used as the sensor 16. However, it goes without saying that the same applies to a case where a sensor such as a micro switch or a reflection type photo sensor is used.

<Embodiment 2> FIG. 12 is a schematic diagram of electrical control according to a second embodiment of the present invention, and the other configuration is the same as that of the first embodiment.

28 is a microcomputer whose input terminal IN1
A photo sensor 16 for detecting the position of the film 11 is connected to the camera. A solenoid 23 is connected to the OUT1 terminal. The rotation control signal of the motor 27 which also drives the fixing device is output to the OUT2 terminal in the same manner as that shown in FIG. 7 of the first embodiment.

A power supply of +5 V is connected to the VDD terminal, and a battery 30 is also connected via a diode 29 at the same time. Also GN
The D terminal is connected to the ground.

Although not shown, other input signals of the copier using the present fixing device and terminals for input signals are provided, and a microcomputer 28 stores a sequence program for the copying operation of the copier. ROM and RAM
However, there is no built-in nonvolatile RAM that retains its stored contents even when the power supply is cut off. However, even if the power of +5 V is cut off, the power is supplied from the above-mentioned battery 30, so that the contents of the RAM in the microcomputer 28 can remain without being erased. Therefore, the same operation as in the first embodiment can be performed, and it is needless to say that the same effect is obtained.

Third Embodiment FIGS. 13 to 16 show a third embodiment. In the configuration of the present embodiment, the solenoid 23 is replaced with a monostable latching solenoid 31 in the configuration of the first embodiment.

 FIG. 13 shows a schematic diagram of the electric control.

First, a microcomputer 32 has a photo sensor 1 for detecting the position of the film 11 at an input terminal IN1.
6 is connected. The OUT1 terminal and the OUT2 terminal are connected to a monostable latching solenoid 31 (hereinafter, a latching solenoid). This is because the latching solenoid used in this embodiment is of the two-winding type, the winding on the suction side is connected to the OUT1 terminal, and the winding on the release side is OU.
Connected to T2 terminal. The OUT3 terminal outputs a rotation control signal of the motor 27 that also drives the fixing device.

The + 5V power supply is connected to the VDD terminal, and the GND terminal is connected to the ground.

Although not shown, other input and output signal terminals of the copying machine using the present fixing device are provided, and a sequence program for the copying operation of the copying machine is programmed in the microcomputer 32. ROM and RAM
And so on.

Here, the latching solenoid 31 will be described. A permanent magnet is built in the solenoid, and when a plunger is pulled by applying a voltage to the attraction side winding, the plunger is held by the permanent magnet. Therefore, it is not necessary to apply a voltage to the suction side winding. Further, when a voltage is applied to the release side winding, a magnetic force is generated so as to cancel the magnetic force of the permanent magnet, and the holding of the suction is released by the action of the compression spring 22 as shown in FIG. Also in this case, it is unnecessary to apply a voltage to the release-side winding after the release. From this, a pulse voltage may be applied to each winding of the latching solenoid, and in this embodiment, a pulse voltage having a pulse width of 100 ms is applied.

14 and 16 show a flowchart of the film shift control program of the present embodiment.

This program is also programmed in the built-in ROM in the microcomputer 32, and is called and executed at regular time intervals or by a main sequence program or the like as needed.

First, after starting, in step 101 (Fig. 14)
It is determined whether the motor 27 is ON.

If the motor 27 is ON, the process proceeds to step 104. If the motor 27 is OFF, the process returns to step 101 and waits until the motor 27 is turned on.

Next, in step 104, it is determined whether or not the sensor 16 is ON. When the sensor 16 is OFF, the process proceeds to step 108, and when the sensor 16 is ON, the process proceeds to step 105.

In step 105, the value of the error timer is reset to 0, measurement is started, and the process proceeds to step 106.

In step 106, it is determined whether or not the sensor 16 is ON. If not, the process proceeds to step 107.

In step 107, an error check routine is executed, and the process returns to step 106.

Here, the content of the error check routine will be described with reference to FIG. 16. First, in step S101, the motor 27
Judge whether it is ON or not.
Move to S102, if not ON, step 113 (Fig. 15)
Move to.

In step S102, it is determined whether or not the error timer value is greater than d seconds. If the error timer value is less than d seconds, the process proceeds to the exit of this routine. If the error timer value is longer than b seconds in step S102, the process proceeds to step S103.

In step S103, an error flag is set, and the routine goes to the exit of this routine.

Next, in step 106 (FIG. 14), the sensor 16 is turned on.
In the case of, the process proceeds to step 108 to reset the value of the error timer to 0, start the measurement, and proceed to step 109.

In step 109, it is determined whether or not the sensor 16 is OFF. If the sensor 16 is not OFF, the process proceeds to step 110, executes an error check routine, returns to step 109, and returns to step 109.
If 6 is turned off, the process proceeds to step 111, where the value of timer 1 is reset to 0, and measurement is started.
Move on to 2 (Fig. 15).

In step 112, it is determined whether or not the motor 27 is ON. If the motor 27 is ON, the process proceeds to step 114.

In step 114, it is determined whether or not the sensor 16 is ON. If the sensor 16 is not ON, the process proceeds to step 115 to execute an error check routine and returns to step 114. If it is ON, the process proceeds to step 116.

In step 116, a comparison is made as to whether the value measured by the timer 1 is smaller than d / 4 seconds. If the value is smaller than this, it can be determined that the film 11 is located on the near side. The suction release drive signal of 31 is output to switch the approach direction of the film 11 to the back side, and the process proceeds to step 120.

If it is determined in step 116 that the value measured by the timer 1 is not smaller than d / 4 seconds, the process proceeds to step 118.

In step 118, a comparison is made as to whether or not the measured value of the timer 1 is greater than 3d / 4 seconds. If not, the process proceeds to step 120, and if it is greater, it is determined that the film 11 is located on the back side. Therefore, the process proceeds to step 119, where a suction drive signal for the solenoid 32 is output, and the direction in which the film 11 is shifted is switched to the near side, and then the process proceeds to step 120.

In step 120, the value of the error timer is reset to 0, and measurement is started.

In step 121, it is determined whether or not the sensor 16 is OFF. If the sensor 16 is not OFF, the process proceeds to step 122, executes an error check routine, and returns to step 121.

If the sensor 16 is OFF in step 121, the process proceeds to step 123, where the value of the timer 1 is reset to 0, measurement is started, and the process returns to step 112.

If the motor 27 is OFF in step 112, the process proceeds to step 113. First, the measurement of the timer 1 is stopped, the measured value is reset to 0, and the process returns to step 101 (FIG. 14).

Note that the film abnormality processing program, which is a part of the main program, is the same as that in the first embodiment, and a description thereof will be omitted.

As described above, when the sensor 16 is ON during motor rotation, wait until the sensor 16 is OFF, and when the sensor 16 is OFF,
It waits until it turns on and then turns off, detects the timing when the output of the film position sensor 16 switches from ON to OFF, and ends the initial setting. The sensor 16 until the next time the sensor 16 switches from OFF to ON
The position of the film 11 is detected only after measuring the OFF time of. That is, the control of the film 11 is disabled until the time when the OFF time of the first sensor 16 is measured, but since the latching solenoid 32 is set in the direction in which the control was performed up to that time, the aforementioned control is disabled. The film is prevented from abnormally approaching either end during the state. Thereafter, the OFF time of the sensor 16 from the time when the sensor 16 switches from ON to OFF to the time when the sensor 16 switches from OFF to ON is measured, and the film position is controlled so as to be within a predetermined control range. Also, by using a latching solenoid, the solenoid
Since only a pulsed voltage needs to be applied to ON / OFF, there is also an energy saving effect.

(Effects of the Invention) As described above, the rotation endless film shift control has a mechanism for switching the endless film shift direction to perform the shift control, and has a non-volatile means for storing the endless film shift direction. With the device, even in a case such as immediately after the power is turned on, it is possible to set the shift control direction up to the start of the shift control at the same time as the start of the shift control.

In this way, if the speed difference due to the shift direction is large during the shift control disabled state from the start of the control to the detection of the initial film position and the actual shift control being enabled, the endless film is moved in either of the width directions. This has the effect of preventing damage to the edge of the.

Of course, this makes it possible to prevent the fixing device using the endless film as described above from being damaged, and at the same time, it is possible to control the deviation even if the speed difference due to the deviation direction of the endless film is large, so that the endless film can be controlled. Accuracy is no longer required for tension adjustment,
In addition, there is an effect that the design margin is increased.

Therefore, by applying the present invention to a fixing device using an endless film as in the above-described example, it is possible to greatly improve the reliability and practicality of this type of fixing device.

[Brief description of the drawings]

FIG. 1 is a partially omitted plan view of an example of a fixing device to which a film shift control device according to the present invention is applied. FIG. 2 is a side view thereof. FIG. 3 is a schematic configuration diagram of an example of an image forming apparatus. FIG. 4 is an outline drawing of an endless film. FIG. 5 is a diagram showing the relationship between the film sensor and the film position. FIG. 6 is a graph showing the relationship between film position and film sensor output. FIG. 7 is a schematic diagram of the electric control of the first embodiment. 8 to 11 are flowcharts of the shift control program according to the first embodiment. FIG. 12 is a schematic diagram of the electric control of the second embodiment. FIG. 13 is a schematic diagram of electric control according to the third embodiment. 14 to 16 are flowcharts of the shift control program according to the third embodiment. 11 is an endless film fixing sheet, 12 is a driven roller,
13 is a drive roller, 14 is a fixing heater, 15 is a pressure roller, 16
Is a photo sensor, 23 is a solenoid, 26, 28, and 32 are microcomputers, 27 is a motor, 30 is a battery, and 31 is a monostable latching solenoid.

Claims (1)

(57) [Claims] 1. A fixing device having a film that moves in contact with a recording material bearing an unfixed image, wherein the deviation control means controls a deviation of the film in a direction orthogonal to a direction in which the film moves. Storage means for storing the direction of the film shift according to (1), wherein, when power is supplied to the apparatus, the shift control means controls the shift of the film based on the contents stored in the storage means. apparatus.