JPH11296015A - Fixing device and image forming device provided with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of directly detecting the winding onto a fixing body or a pressure body, of a recording medium, while maintaining the life of the fixing body or the pressing body over a long period, and an image forming device provided with the fixing device. SOLUTION: In the fixing device, a system controller 71 decides the presence of the occurrence of the winding onto a fixing roller 39A or a pressure roller 39B, of the recording medium P, in accordance with the difference between the derivation obtained in such a manner that output values from respective temperature detectors 39C and 39D by the detections of the temperatures of the respective temperature detectors 39C and 39D are differentially operated according to the difference from a reference differential value TS as a comparison reference value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for applying a fixing process to a recording medium carrying an unfixed image by applying heat and pressure, and more particularly to winding the recording medium around a fixing member or a pressing member. The present invention relates to a fixing device capable of determining whether or not occurrence has occurred, and an image forming apparatus including the fixing device.

[0002]

2. Description of the Related Art In an image forming apparatus, generally, an unfixed image carried on a recording medium is formed between a fixing member and a pressing member which are pressed against each other in accordance with externally provided information. During the passage of the recording medium through the nip portion, a fixing process to the recording medium is performed by a process of melting and permeating the recording medium by heating of a heating unit supplied with electric power from a commercial power supply.

[0003] Therefore, the viscosity of the unfixed image carried on the recording medium is increased by the heating of the heating means, so that the recording medium may often be wrapped around the fixing member.

Therefore, conventionally, a separating member for separating the recording medium wound around the fixing member from the fixing member by sliding the claw portion in sliding contact with the fixing member is provided.
It has been attempted to prevent the recording medium from winding around the fixing member.

Further, a passage detecting means for detecting whether or not the recording medium has passed is provided at a position downstream from the nip in the conveying direction of the recording medium, so that the nip of the recording medium carrying the unfixed image is provided. If the passage detecting means does not detect the passage of the recording medium after a lapse of a predetermined time from the start of passage of the recording medium, the recording medium is jammed in the nip portion (hereinafter, the jamming of the recording medium in the nip portion is referred to as a jam). )
Thus, an indirect determination has been made as to whether the recording medium has been wound around the fixing member.

[0006]

However, in the conventional method for preventing the recording medium from being wound around the fixing member by the separator, the basis weight (weight per unit area) is particularly important.
In order to prevent the recording medium having a small size from winding around the fixing body, it is necessary to increase the sliding contact pressure for bringing the claw-shaped part of the separation body into sliding contact with the fixing body. Therefore, it was difficult to maintain the life of the fixing member for a long period of time.

Conventionally, in determining whether the recording medium has been wrapped around the fixing member by the conventional passage detecting means, it is determined whether or not the wrapping has occurred through the determination of the occurrence of a jam. Was indirectly performed, so that it was difficult to distinguish between the occurrence of the wrapping and the occurrence of the jam.

In view of the above, the present invention provides a fixing device or a fixing device which can directly determine whether the recording medium is wrapped around the fixing member or the pressure member while maintaining the life of the fixing member or the pressure member for a long period of time. It is an object of the present invention to provide an image forming apparatus including the fixing device.

[0009]

According to the present application, the object is to pass a recording medium carrying an unfixed image through a nip formed between a fixing member and a pressing member pressed against each other. A fixing device that performs a fixing process on the recording medium by heating a heating unit that generates heat by receiving power supply from a commercial power supply, and detects a temperature of a temperature detector that detects a temperature of a fixing body or a pressure body. In a fixing device for an image forming apparatus in which power supply from a commercial power supply to a heating unit is adjusted accordingly, the image forming apparatus determines whether winding of the recording medium around a fixing body or a pressure body has occurred. A determination unit is provided, and the determination unit is configured to determine the occurrence of the winding in accordance with a comparison between a comparison reference value that is a comparison reference for the determination of the occurrence of the winding and an output value from the temperature detector by detecting the temperature of the temperature detector. How Also achieved by a first aspect of the present invention that is configured to constant.

Further, according to the present application, the above object is achieved in the first invention according to the present application, wherein the temperature detector detects the amount of infrared radiation from the fixing body or the pressure body due to the heating of the heating means. An infrared detecting element for converting the detected infrared radiation amount into a temperature value, and a temperature compensating element for compensating the temperature value converted by the infrared detecting element, the temperature of the fixing body or the pressure body based on the infrared radiation amount This is also achieved by the second invention of detecting

Further, according to the present application, the above object is achieved in the first invention or the second invention according to the present application, wherein the judging means comprises an output value from the temperature detector based on temperature detection of the temperature detector. In accordance with the difference between the differential value obtained by performing the differential operation on the differential operation and the reference differential value serving as the comparison reference value, it is determined whether the recording medium has wrapped around the fixing member or the pressure member. This is also achieved by the third invention.

According to the present application, the above object is achieved by any one of the first to third inventions according to the present application.
The fixing member is a cylindrical or substantially cylindrical rotatable fixing roller, and the temperature detector is also achieved by the fourth invention in which the temperature detecting member is disposed close to the outer peripheral surface of the fixing roller.

Further, according to the present application, the above object is achieved according to any one of the first to fourth inventions according to the present application, wherein the pressurizing body is a cylindrical or substantially cylindrical rotatable heating member. The pressure roller is also achieved by the fifth invention in which the temperature detector is arranged close to the outer peripheral surface of the pressure roller.

Further, according to the present application, an object of the present invention is to provide an image forming apparatus which forms an image in accordance with externally provided information, and then fixes and records the image on a recording medium. The fixing device according to the first aspect of the present invention, and a determining unit for determining whether the winding of the recording medium around the fixing body or the pressing body, wherein the determining unit is a comparison which is a comparison standard of the winding occurrence determination. The present invention is also achieved by the sixth invention in which setting is made to determine whether or not the winding has occurred, based on a comparison between a reference value and an output value from the temperature detector by temperature detection of the temperature detector.

Further, according to the present application, the above object is attained in the sixth invention according to the present application, wherein the temperature detector detects the amount of infrared radiation from the fixing body or the pressure body due to the heating of the heating means. An infrared detecting element for converting the detected infrared radiation amount into a temperature value, and a temperature compensating element for compensating the temperature value converted by the infrared detecting element, the temperature of the fixing body or the pressure body based on the infrared radiation amount This is also achieved by the seventh invention of detecting

Further, according to the present application, the above object is achieved in the sixth or seventh invention according to the present application, wherein the judging means comprises an output value from the temperature detector based on temperature detection of the temperature detector. In accordance with the difference between the differential value obtained by performing the differential operation on the differential operation and the reference differential value serving as the comparison reference value, it is determined whether the recording medium has wrapped around the fixing member or the pressure member. The invention is also achieved by the eight inventions.

Further, according to the present application, the above object is achieved in any one of the sixth to eighth inventions according to the present application, wherein the fixing member is a cylindrical or substantially cylindrical rotatable fixing roller. This is also achieved by the ninth invention in which the temperature detector is arranged close to the outer peripheral surface of the fixing roller.

Further, according to the present application, the above object is achieved by any one of the sixth to ninth inventions according to the present application.
The pressing body is a cylindrical or substantially cylindrical rotatable pressure roller, and the temperature detecting body is also achieved by the tenth invention in which the temperature detecting body is disposed close to the outer peripheral surface of the pressing roller. .

That is, in the first invention according to the present application, the determining means compares the comparison reference value with the output value from the temperature detector by detecting the temperature of the temperature detector, and determines whether the recording medium has It is determined whether or not wrapping around the fixing member or the pressure member has occurred.

In the second invention according to the present application,
The temperature detector detects the temperature of the fixing body or the pressing body based on the amount of infrared radiation from the fixing body or the pressing body, and the determination unit determines a comparison reference value and the temperature from the temperature detecting body by detecting the temperature of the temperature detecting body. According to the comparison of the output values, it is determined whether or not the winding of the recording medium around the fixing body or the pressure body has occurred.

Further, in the third invention according to the present application, the judging means performs a differential operation on the output value from the temperature detector by detecting the temperature of the temperature detector to obtain a differential value. It is determined whether the recording medium is wrapped around the fixing member or the pressure member according to the difference between the value and the reference differential value as the comparison reference value.

Further, in the fourth invention according to the present application,
The temperature of the outer peripheral surface is detected by a temperature detector disposed close to the outer peripheral surface of the fixing roller.

Further, in the fifth invention according to the present application, the temperature of the outer peripheral surface is detected by a temperature detector disposed close to the outer peripheral surface of the pressure roller.

In the sixth invention according to the present application,
The determining means determines whether the recording medium is wrapped around the fixing member or the pressure member in accordance with the comparison between the comparison reference value and the output value from the temperature detector based on the temperature detection of the temperature detector.

Further, in the seventh invention according to the present application, the temperature detector detects the temperature of the fixing member or the pressing member based on the amount of infrared radiation from the fixing member or the pressing member, and the determining means determines the temperature of the fixing member or the pressing member. In accordance with the comparison between the comparison reference value and the output value from the temperature detector based on the temperature detection of the temperature detector, it is determined whether the recording medium is wrapped around the fixing member or the pressure member.

In the eighth invention according to the present application,
The determining means records the difference between a differential value obtained by performing a differential operation on an output value from the temperature detector by the temperature detection of the temperature detector and a reference differential value serving as a comparison reference value. It is determined whether the medium is wrapped around the fixing member or the pressure member.

Further, in the ninth invention according to the present application, the temperature of the outer peripheral surface is detected by a temperature detector disposed close to the outer peripheral surface of the fixing roller.

In the tenth invention according to the present application,
The temperature of the outer peripheral surface is detected by a temperature detector arranged close to the outer peripheral surface of the pressure roller.

[0029]

Embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic sectional view showing a schematic configuration of an example of an image forming apparatus suitably showing the present embodiment.

As shown in FIG. 1, the image forming apparatus according to the present embodiment mainly includes a reader unit 1 for reading information provided from a document M and then performing image processing and forming an image corresponding to the information provided. The printer unit 2 is configured to perform recording on the recording medium P.

The reader unit 1 includes a document table 1 on which a document is placed.
1. A document pressure plate 12 for pressing a document placed on a document table 11 from above, a light source 13 for irradiating an image surface (a surface on which provided information is formed) of the document M, and a light reflected from the image surface It comprises mirrors 14, 14, 14 and a lens 15, an image processing section 16 for performing various image processing on image signals obtained by photoelectrically converting reflected light by a CCD, and the like.

The image processing unit 16 includes a CCD, an A / D converter,
Image processing functions such as S / H, shading correction, masking correction, scaling, and LOG conversion are provided.

Next, a process from reading of the provided information of the document M in the reader unit 1 to image processing will be described.

First, after placing the original M at a predetermined position on the original platen 11 so that the image surface of the original M faces downward,
The document M is pressed from above by the document pressure plate 12 to the predetermined position.

Next, the image surface of the original M is scanned by irradiating the original M with light while the light source 13 moves in the direction of the arrow Kl.

Accordingly, the reflected light image from the image surface of the original M is formed on the image processing section 16 via the mirrors 14, 14, and 14 and the lens 15, and is subjected to various image processing after being photoelectrically converted into an image signal. After being applied, it is output to the printer unit 2.

As shown in FIG. 1, the printer unit 2 includes an image control unit 17 for converting an output signal from the reader unit 1 into a signal for driving the laser element 18, and a photosensitive drum 30.
Is constituted by a polygon scanner 19 that scans the outer peripheral surface with the laser light from the laser element 18, a fixing device 39, and the like.

The photosensitive drum 30 is a drum-like body rotatably supported, and in the present embodiment, is driven to rotate in the direction of the arrow as shown in FIG.

Around the photosensitive drum 30, a primary charger 31 for uniformly charging the outer peripheral surface of the photosensitive drum 30 in preparation for forming an electrostatic latent image, and developing the electrostatic latent image carried on the outer peripheral surface. Developing device 20 for visualizing a developer image with a developer, transfer charger 35 for transferring the developer image formed on the outer peripheral surface to recording medium P, and cleaner for removing residues on the outer peripheral surface after transfer processing 34, a pre-exposure lamp 32 and a pre-exposure lamp 3 for eliminating charges remaining on the outer peripheral surface after the transfer process
An auxiliary charger 33 and the like for assisting the static elimination processing by the second unit 2 are arranged.

The main body of the developing device 20 includes a photosensitive drum 30
Developing roller 20 that is driven to rotate in a direction opposite to the rotation direction of
a is rotatably supported.

That is, when the developer on the outer peripheral surface of the developing roller 20a is attracted to the electrostatic latent image on the outer peripheral surface of the photosensitive drum 30, the developing process of the electrostatic latent image is performed.

Therefore, the recording medium P carrying the unfixed image
Is conveyed to the fixing device 39 by the conveyance belt 37, and is subjected to a fixing process by being heated and pressed while passing through the nip portion N, and finally, the recording medium P after the fixing process is transferred to the image forming apparatus. The paper is discharged outside the main body.

In the image forming apparatus of the present embodiment, a paper feed path and a transport path for feeding and transporting the recording medium P are provided, and the most upstream position in the transport path of the recording medium in the transport path, Paper cassette 36, paper feed roller 36a,
A transport roller 36b and the like are arranged.

A multi-feeding device 38 is attached to the side surface of the image forming apparatus of the present embodiment, and a path from the multi-feeding device 38 to a transfer space between the photosensitive drum 30 and the transfer charger 35 is provided. Because it is straight,
Various recording media P having different materials and sizes can be supplied to the transfer space.

Next, the fixing device 39 will be described with reference to FIG. FIG. 2 is a schematic sectional view showing a schematic configuration of the fixing device 39.

The fixing device 39 includes a cylindrical or substantially cylindrical rotatable fixing roller 39A as a fixing member, and a cylindrical or substantially cylindrical rotatable pressure roller 39 as a pressing member.
B, halogen heaters 208 and 209 (hereinafter, abbreviated as heaters 208 and 209) as heating means, and temperature detectors 39C and 39D.

The pressure roller 39B is fixed to the fixing roller 3 by a pressure mechanism (not shown) provided outside the fixing device 39.
Pressurized to 9A.

Therefore, the fixing roller 39A and the pressure roller 3
When the fixing rollers 9B are in pressure contact with each other, a driving force is transmitted from a driving mechanism (not shown) provided outside the fixing device 39 to one of the fixing roller 39A and the pressing roller 39B, so that the one roller is driven. The recording medium P carrying the unfixed image that has entered the nip portion N moves from the upstream side to the downstream side in the roller rotation direction by being driven to rotate, whereby the other roller follows the rotation of the one roller. The nip portion N is passed.

In each hollow portion formed in each of the fixing roller 39A and the pressure roller 39B, a heater 208 and a heater 209 are arranged in parallel or substantially in parallel with each axial direction.

Each of the heaters 208 and 209 is
Each of the temperature detectors 39C, 3C is connected via a heater drive circuit 210 for turning on and off the heaters 208, 209.
In accordance with the detection result of 9D, it is controlled by a system controller 71 as a determining means.

That is, when the temperature of the fixing roller 39A does not coincide with the temperature value within a predetermined width from the target temperature, the system controller 71, through the heater drive circuit 210, according to the detected temperature of the temperature detector 39C. Heater 2
The control of turning on and off 08 is performed.

When the temperature of the pressure roller 39B does not coincide with the temperature value within a predetermined width from the target temperature, the system controller 7 according to the temperature detected by the temperature detector 39D.
1 through the heater drive circuit 210, the heater 20
9 is turned on and off.

The heaters 208 and 209 receive AC power from a commercial power supply (not shown) provided outside the fixing device 39 and generate heat. If the power supply is
The heater drive circuit 210 includes an SSR (Solid State Relay) or the like that can switch the power supply to the power supply 8 and 209 between conductive and cutoff.

Temperature detector 39C and temperature detector 39D
Are disposed close to the outer peripheral surfaces of the fixing roller 39A and the pressure roller 39B, respectively. The detection results of the temperature detector 39C and the temperature detector 39D are obtained by converting the input analog information into digital information, respectively. Analog-to-digital converter 201 and analog-to-digital converter 202 (hereinafter, A / D conversion circuits 201 and A
Abbreviated as / D conversion circuit 202. ) To perform various controls in the image forming apparatus, that is, a built-in CPU
Output to the system controller 71 which performs the above various controls in an integrated manner.

The arrangement of the temperature detectors 39C and 39D is not limited, but may be, for example, the fixing roller 39A.
And in view of the achievement of prolonged life of each of the pressure rollers 39B,
Disposing the respective temperature detectors 39C and 39D close to the respective outer peripheral surfaces of the fixing roller 39A and the pressing roller 39B means that the respective temperature detectors 39C and 39D are disposed in contact with the respective outer peripheral surfaces. More desirable.

The temperature detector 39C is, as shown in FIG.
Among the radiation from the outer peripheral surface of the fixing roller 39A, an infrared-pass filter (not shown) that passes only infrared rays, and a condenser lens LE1 that collects the infrared rays that have passed through the infrared-pass filter.
And an infrared detecting element 203 that detects infrared light condensed by the condenser lens LE1 and converts it into a temperature value to output to the A / D conversion circuit 201; and a detection temperature obtained by detecting the temperature of the temperature detector 39C. Is output to the A / D conversion circuit 201. The thermistor temperature sensing element 205 (hereinafter, abbreviated as the thermistor 205) as a temperature compensating element is provided.

The temperature detector 39D is provided with a pressure roller 39.
Among the radiation from the outer peripheral surface of B, an infrared-pass filter (not shown) that passes only infrared rays, a condenser lens LE2 that collects infrared rays that have passed through the infrared-pass filter, and a condenser lens LE2 Infrared detecting element 20 which detects the detected infrared light, converts it into a temperature value, and outputs it to A / D conversion circuit 202
4, a thermistor temperature sensing element 206 serving as a temperature compensating element set to output the detected temperature obtained by detecting the temperature of the temperature detecting body 39D itself to the A / D conversion circuit 202.
(Hereinafter, abbreviated as the thermistor 206).

Therefore, the temperature detector 39C and the temperature detector 3
9D, in the present embodiment, each heater 208, 20
9. The fixing roller 39A and the pressure roller 3 caused by the heat
The temperature of each outer peripheral surface is set to be detected based on the amount of infrared radiation from each outer peripheral surface of 9B.

That is, the temperature detector 39C and the temperature detector 3
9D detects the temperatures of the outer peripheral surfaces of the fixing roller 39A and the pressing roller 39B by the A / D conversion circuit 201 and the A / D
The conversion circuit 202 outputs the output temperature values from the infrared detection elements 203 and 204 and the thermistor 205
It is set to be calculated based on a difference between the output temperature value from the thermistor 206 and each output temperature value.

Next, the temperature detector 39C and the temperature detector 3
A process of determining whether the recording medium P is wound around the fixing roller 39A and the pressure roller 39B by 9D will be described with reference to FIGS.

FIGS. 3A and 3B are graphs showing the transition of the measured value of the fixing roller 39A. FIG.
It is a graph which shows the temperature transition of the outer peripheral surface of 9A,
(B) is a graph showing a differential transition of the temperature of the outer peripheral surface when the recording medium P is wound around the fixing roller 39A.

The graph relating to the temperature on the outer peripheral surface of the pressure roller 39B and its differential change is shown in FIG.
Since the graph is similar to the graph relating to the temperature and its differential transition at A, the description of the process of detecting the winding of the recording medium P around the pressure roller 39B will be omitted instead of the following description.

The turning on and off of the heaters 208 and 209 are controlled by the system controller 71 via the heater driving circuit 210 so that the outer peripheral surface of the fixing roller 39A matches a temperature value within a predetermined width from the target temperature. It has become.

Therefore, the temperature (solid line) of the outer peripheral surface of the fixing roller 39A periodically fluctuates within a predetermined width from the target temperature as shown in FIG.

It is needless to say that the temperature fluctuation period of the outer peripheral surface of the fixing roller 39A changes depending on various factors such as the ambient temperature around the fixing roller 39A, the material and size of the recording medium P, and the like.

Therefore, when the recording medium P is wound around the outer peripheral surface of the fixing roller 39A, the temperature of the outer peripheral surface changes as shown by a dotted line.

That is, for example, the fixing roller 3 of the recording medium P
When winding around the outer peripheral surface of 9A occurs, the temperature of the outer peripheral surface temporarily decreases from the temperature value of the solid line due to the heat absorption of the recording medium P at the same time or almost at the same time as the occurrence of the winding. As the thermal equilibrium between P and the fixing roller 39A is gradually achieved, the temperature of the outer peripheral surface converges to the temperature value indicated by the solid line.

Therefore, in the present embodiment, a differential operation is sequentially performed on the temperature of the outer peripheral surface of the fixing roller 39A, and a differential signal obtained by the differential operation is transmitted to the system controller 71.
Thus, it is determined whether or not the recording medium P has been wound around the fixing roller 39A and the pressure roller 39B.

Hereinafter, the differential operation performed in this embodiment will be described.

In the image forming apparatus of the present embodiment, since the image forming speed on the recording medium P is set to 50 sheets / sec, the temperature monitor sample rate is 10 msec.
c.

In the present embodiment, since the digital information output from the A / D conversion circuits 201 and 202 is differentiated by the system controller 71, the differential coefficient in the differential operation is expressed as (-1) −1 −16 −1 −1 −1)... D−3 d−2 d−1 d d + 1 d + 2 d + 3.
Reference numeral 1 denotes the data to be differentiated, and the data to be differentiated before and after one of d.

Needless to say, the above differential coefficients are set according to the ambient temperature around the fixing roller 39A and the pressure roller 39B, the material and size of the recording medium P, and the like.

Next, an algorithm for determining whether the recording medium P is wound around the fixing roller 39A and the pressure roller 39B will be described with reference to FIG.

FIG. 4 shows the fixing roller 39 of the recording medium P.
9 is a flowchart showing an algorithm for determining whether winding has occurred around A and the pressure roller 39B.

Whether the winding of the fixing roller 39A of the recording medium P has occurred is determined by the system controller 71.
This is performed by performing arithmetic processing by U.

The temperature rise and maintenance of the fixing roller 39A to the target temperature are performed irrespective of the fixing processing step and the fixing processing standby step. On the other hand, it is determined whether the recording medium P is wound around the fixing roller 39A. Only the fixing process is performed.

First, the temperature control of the outer peripheral surfaces of the fixing roller 39A and the pressure roller 39B during the fixing process is started (step S20).

Next, the fixing roller 39A and the pressure roller 3
The temperature of each outer peripheral surface of 9B is measured by the temperature detectors 39C and 39D (Step S21).

Hereinafter, the fixing roller 39A and the pressure roller 3
The temperature of each outer peripheral surface of 9B is represented as TU and TL, respectively.

Therefore, by sequentially differentiating each digital information output from the A / D conversion circuits 201 and 202 on the basis of the above differential coefficients, the temperature differential TU 'corresponding to each of the temperature TU and the temperature TL is obtained. And the temperature derivative T
L ′ is calculated (step S22).

Therefore, when the recording medium P is wrapped around the fixing roller 39A or the pressure roller 39B, the temperature derivative corresponding to the temperature of the wrapped roller shows the transition in FIG. 3B. Therefore, it is determined whether the temperature differentiation has exceeded the reference temperature differentiation TS, which is a reference differentiation value (step S23).

Therefore, the fixing roller 39A or the pressing roller 3
9B exceeds the reference temperature differential TS, the recording medium P to the roller corresponding to the temperature differential is determined.
Is determined to have occurred, and the heater disposed in the hollow portion of the roller is driven by the heater driving circuit 210.
(Step S24).

Further, the display unit (not shown) displays whether the roller on which the recording medium P has actually been wound is the fixing roller 39A or the pressure roller 39B (step S25). The temperature control process and the fixing process of each outer peripheral surface of the pressing roller 39A and the pressing roller 39B are stopped (step S26).

On the other hand, the fixing roller 39A or the pressure roller 3
If the temperature derivative corresponding to 9B does not exceed the reference temperature derivative TS, it is determined that the recording medium P has not been wound around the fixing roller 39A and the pressure roller 39B,
The normal temperature control process currently performed is continued.

In the ordinary temperature control step, the temperature TU
Alternatively, when the temperature TL has decreased from the target temperature to a temperature Ton outside the predetermined width (step S27), the heater disposed in the hollow portion of the roller indicating the temperature Ton is turned on, and then the fixing roller 39A and the heating roller are again turned on. The process returns to the temperature detection of each outer peripheral surface of the pressure roller 39B (Step S21).

On the other hand, when the temperature TU or the temperature TL rises from the target temperature to the temperature Toff outside the predetermined width (step S29), after the heater disposed in the hollow portion of the roller indicating the temperature Toff is turned off, Again, the fixing roller 3
The process returns to the detection of the temperatures of the outer peripheral surfaces of 9A and the pressing roller 39B (step S21).

Further, when the temperature TU or the temperature TL indicates a temperature value in the range from Ton to Toff, in order to avoid excessive lighting of the heaters 208 and 209, each heater 2
The process returns to the temperature detection of the outer peripheral surfaces of the fixing roller 39A and the pressing roller 39B again without switching between turning on and off of 08 and 209 (step S2).
1).

That is, the range from the temperature Ton to the temperature Toff is a dead zone region in the temperature control.

The target temperature, the temperature Ton and the temperature Tof
The magnitude relation of f is as follows: temperature Ton <target temperature <temperature Toff
Has been adopted.

Therefore, in the present embodiment, the system controller 71 performs a differential operation on the output value from each of the temperature detectors 39C and 39D based on the temperature detection of the temperature detectors. It is determined whether the recording medium P is wrapped around the fixing roller 39A and the pressure roller 39B according to the difference between the value and the reference differential value TS as the comparison reference value.
It is possible to directly determine whether the recording medium P is wrapped around the fixing roller 39A and the pressure roller 39B while maintaining the life of the recording medium 9B for a long time.

In this embodiment, the temperature detector 3
9C and the temperature detector 39D are respectively fixed to the fixing roller 39A.
And the pressure detecting member 39C and the temperature detecting member 39D
The friction between the fixing roller 39A and the pressing roller 39B is prevented without friction between the fixing roller 39A and the pressing roller 39B.
The advantage is that the life of the device can be further maintained over a long period of time.

[0093]

As described above, according to the first aspect of the present invention, the judging means determines the comparison reference value and the output value from the temperature detector by detecting the temperature of the temperature detector. It is determined whether the recording medium is wrapped around the fixing member or the pressure member according to the comparison. Therefore, while maintaining the life of the fixing member or the pressure member for a long time, the fixing member or the pressure member of the recording medium is It is possible to directly determine whether wrapping around the body has occurred.

Further, according to the second aspect of the present invention, the temperature detector detects the temperature of the fixing member or the pressing member based on the amount of infrared radiation from the fixing member or the pressing member, and the determining means determines the temperature of the fixing member or the pressing member. It is determined whether the recording medium is wrapped around the fixing member or the pressure member according to the comparison between the comparison reference value and the output value from the temperature detecting member based on the temperature detection of the temperature detecting member. It is possible to directly determine whether the recording medium has been wound around the fixing member or the pressing member while maintaining the life of the pressing member for a long period of time.

Further, according to the third invention of the present application,
The determining means records the difference between a differential value obtained by performing a differential operation on an output value from the temperature detector by the temperature detection of the temperature detector and a reference differential value serving as a comparison reference value. Since it is determined whether the medium is wrapped around the fixing body or the pressing body, it is determined whether the recording medium is wrapped around the fixing body or the pressing body while maintaining the life of the fixing body or the pressing body for a long period of time. Can be determined directly.

According to the fourth aspect of the present invention, the temperature of the outer peripheral surface is detected by the temperature detector disposed close to the outer peripheral surface of the fixing roller. Long-term maintenance can be further achieved.

Further, according to the fifth invention of the present application,
Since the temperature of the outer peripheral surface is detected by the temperature detector disposed close to the outer peripheral surface of the pressure roller, the life of the pressure roller can be further maintained for a long time.

[0098] According to the sixth aspect of the present invention, the judging means compares the comparison reference value and the output value from the temperature detector by detecting the temperature of the temperature detector to determine whether or not the recording medium is to be used. Since it is determined whether the wrapping around the fixing body or the pressing body occurs, it is possible to directly determine whether the wrapping of the recording medium around the fixing body or the pressing body while maintaining the life of the fixing body or the pressing body for a long time. An image forming apparatus including a fixing device capable of making a determination can be provided.

Further, according to the seventh invention of the present application,
The temperature detector detects the temperature of the fixing body or the pressing body based on the amount of infrared radiation from the fixing body or the pressing body, and the determination unit determines a comparison reference value and the temperature from the temperature detecting body by detecting the temperature of the temperature detecting body. According to the comparison of the output values, it is determined whether the recording medium is wrapped around the fixing body or the pressing body, so that the fixing body or the pressing body of the recording medium is maintained while maintaining the life of the fixing body or the pressing body for a long time. It is possible to provide an image forming apparatus provided with a fixing device capable of directly determining whether or not the wrapping around the pressure member has occurred.

According to the eighth aspect of the present invention, the determining means performs a differential operation on the output value from the temperature detector by detecting the temperature of the temperature detector. It is determined whether the recording medium is wrapped around the fixing member or the pressure member according to the difference between the value and the reference differential value serving as the comparison reference value. Therefore, the life of the fixing member or the pressure member is maintained for a long time. Accordingly, it is possible to provide an image forming apparatus provided with a fixing device capable of directly determining whether the winding of the recording medium around the fixing member or the pressure member has occurred.

Further, according to the ninth invention of the present application,
Since the temperature of the outer peripheral surface is detected by a temperature detector disposed close to the outer peripheral surface of the fixing roller, the image forming apparatus includes a fixing device that further maintains the life of the fixing roller for a long period of time. Can be provided.

According to the tenth aspect of the present invention, the temperature of the outer peripheral surface is detected by the temperature detector disposed close to the outer peripheral surface of the pressure roller. It is possible to provide an image forming apparatus including a fixing device in which the life is further maintained for a long time.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present application.

FIG. 2 is a schematic sectional view showing a schematic configuration of the fixing device of FIG.

3A and 3B are graphs showing changes in measured values of the fixing roller shown in FIG. 2, wherein FIG. 3A is a graph showing changes in the temperature of the outer peripheral surface of the fixing roller, and FIG. 5 is a graph showing a differential transition of the temperature of the outer peripheral surface when the winding around the fixing roller occurs.

FIG. 4 is a flowchart illustrating an algorithm for determining whether or not a recording medium has been wound around a fixing roller and a pressure roller illustrated in FIG. 2;

[Explanation of symbols]

 39 fixing device 71 system controller (judgment means) 201 analog-digital converter 202 analog-digital converter 203 infrared detecting element 204 infrared detecting element 205 thermistor temperature detecting element (temperature compensating element) 206 thermistor temperature detecting element (temperature compensating element) 208 Halogen heater (heating means) 209 Halogen heater (heating means) 210 Heater drive circuit 39A Fixing roller (fixing body) 39B Pressure roller (pressing body) 39C Temperature detector 39D Temperature detector LE1 Condensing lens LE2 Condensing lens P Recording medium N Nip

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Katsuhide Koga Inventor Canon Inc. 3- 30-2 Shimomaruko, Ota-ku, Tokyo (72) Inventor Takayuki Kawakami 3- 30-2 Shimomaruko 3-chome, Ota-ku, Tokyo (72) Inventor Yukio Yokoyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (10)

[Claims] 1. A heating means for generating heat by receiving power supply from a commercial power supply while allowing a recording medium carrying an unfixed image to pass through a nip formed between a fixing body and a pressure body pressed against each other. A fixing device that performs a fixing process on the recording medium by heating the recording medium, wherein power supply from a commercial power supply to a heating unit is adjusted according to a temperature detected by a temperature detector that detects a temperature of the fixing body or the pressure body. In a fixing device for an image forming apparatus, the image forming apparatus includes a determination unit that determines whether the winding of the recording medium around a fixing body or a pressure body occurs, and the determination unit determines the occurrence of the winding. According to a comparison between a comparison reference value that is a comparison reference and an output value from the temperature detector by temperature detection of the temperature detector,
The fixing device is set to determine whether the winding has occurred. 2. A temperature detecting element comprising: an infrared detecting element for detecting an amount of infrared radiation from a fixing body or a pressurized body due to heating of a heating unit and converting the detected infrared radiation to a temperature value; The fixing device according to claim 1, further comprising: a temperature compensating element that compensates for the temperature value obtained, and detects a temperature of the fixing member or the pressure member based on the amount of infrared radiation. 3. The determining means according to claim 1, wherein the difference between a differential value obtained by performing a differential operation on an output value from the temperature detector by the temperature detection of the temperature detector and a reference differential value serving as a comparison reference value. 3. The fixing device according to claim 1, wherein whether the recording medium is wound around the fixing member or the pressure member is determined according to the condition. 4. The fixing device according to claim 1, wherein the fixing member is a rotatable fixing roller having a cylindrical or substantially cylindrical shape, and the temperature detecting member is disposed close to an outer peripheral surface of the fixing roller.
The fixing device according to claim 3. 5. The pressure body is a cylindrical or substantially cylindrical rotatable pressure roller, and the temperature detection body is arranged close to the outer peripheral surface of the pressure roller. 1
The fixing device according to claim 4. 6. An image forming apparatus for forming an image according to externally provided information and then fixing and recording the image on a recording medium, wherein the fixing device according to claim 1,
A determination unit that determines whether the winding of the recording medium around the fixing body or the pressing body is generated, wherein the determining unit includes a comparison reference value that is a comparison reference for the determination of the occurrence of the winding, and the temperature based on temperature detection of a temperature detection body. An image forming apparatus characterized in that it is set so as to determine whether the winding has occurred in accordance with a comparison with an output value from a detection body. 7. A temperature detector detects an amount of infrared radiation from a fixing body or a pressurized body due to heating of a heating unit and converts the detected amount of infrared radiation into a temperature value. The image forming apparatus according to claim 6, further comprising a temperature compensating element for compensating the temperature value, and detecting a temperature of the fixing member or the pressure member based on the amount of infrared radiation. 8. A determining means for determining a difference between a differential value obtained by performing a differential operation on an output value from the temperature detector by detecting a temperature of the temperature detector and a reference differential value serving as a comparison reference value. 8. The image forming apparatus according to claim 6, wherein it is determined whether the recording medium is wrapped around the fixing body or the pressure body. 9. The fixing device according to claim 6, wherein the fixing member is a cylindrical or substantially cylindrical rotatable fixing roller, and the temperature detector is disposed close to an outer peripheral surface of the fixing roller.
The image forming apparatus according to claim 8. 10. The pressure member is a cylindrical or substantially cylindrical rotatable pressure roller, and the temperature detection member is disposed close to the outer peripheral surface of the pressure roller. The image forming apparatus according to claim 6.