JP2008026362A - Image heating device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect whether or not paper is wound round a roller in a fixing device, in an image forming apparatus equipped with a non-contact type temperature detection element for detecting the surface temperature of the roller inside the fixing device. <P>SOLUTION: The roller in the fixing device is rotated, in such a state that power supplying is stopped to the heating source in the fixing device, when a fault occurs and when jamming occurs after supplying power; and the winding of the paper round the roller in the fixing device is detected, on the basis of the transition of detected temperature by the non-contact type temperature detection element then. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image heating apparatus for heating an image on a recording material. The present invention also relates to an image forming apparatus in which the image heating apparatus is mounted as a fixing device.

  Examples of the image heating device include a fixing device that heats and fixes an unfixed image on the recording material, and a glossiness increasing device that increases the glossiness of the image by heating the image fixed on the recording material. Can be mentioned.

  In an image forming apparatus such as an electrophotographic apparatus or an electrostatic recording apparatus, an unfixed toner image is formed on a sheet-like recording material such as paper by a transfer method or a direct method (non-transfer method), and this is used as a fixing device. The image is formed by fixing by heating and pressurizing.

  As such a fixing device, a fixing roller having a heater (heating source) and a pressure roller are pressed against each other to form a fixing nip portion, and a recording material is sandwiched and conveyed by the fixing nip portion, so that the toner image A heat roller fixing system for fixing has been widely used.

  The fixing roller is temperature-controlled to a preset fixing temperature necessary for fixing the toner image. That is, the surface temperature of the fixing roller is detected using a temperature detection element such as a thermistor or thermopile, and the detection result is taken into a control unit such as a CPU. The control unit controls energization from the power supply unit to the heater so that the detected temperature information input from the temperature detection element is maintained at the fixing temperature.

  The temperature detection element that detects the surface temperature of the fixing roller uses a non-contact type temperature detection element in order to prevent the fixing roller from becoming dirty and scratched when detecting the temperature of the sheet passing area on the fixing roller. The On the other hand, when detecting the temperature of the non-sheet passing region, a contact-type temperature detecting element with good detection accuracy is used.

  However, when the recording material is wound around the fixing roller, there is a recording material wound between the non-contact temperature detecting element and the fixing roller arranged in the sheet passing area. The temperature cannot be measured accurately. In this case, since the non-contact temperature detecting element measures the temperature of the recording material wound around the fixing roller, it detects a temperature lower than the actual surface temperature of the fixing roller. In other words, the controller that controls the energization of the heater that heats the fixing roller based on the temperature detected by the non-contact temperature detecting element controls the surface temperature of the fixing roller to be higher than that in the normal state. Abnormal temperature rise may occur.

In order to deal with such a problem, Patent Document 1 discloses a method of using a non-contact temperature detection element and a contact temperature detection element to detect winding of a recording material around a fixing roller based on a difference between the detected temperatures of both. Has been.
JP 2004-2558581 A

  The recording material winding detection method described in Patent Document 1 is based on the premise that the longitudinal center portion and the end portion of the fixing roller are heated by the same heating body (heater) or a heating body having the same calorific value. ing.

  However, the heater disposed in the fixing roller is generally a combination of a plurality of heaters having different light distribution characteristics in the longitudinal direction in order to suppress the temperature rise of the non-sheet passing portion of the fixing roller. A temperature difference occurs between the longitudinal center and the end of the fixing roller. Therefore, in such a fixing device, it is difficult to detect the winding of the recording material around the fixing roller by the method described in Patent Document 1.

  It is an object of the present invention to provide a rotating body that heats an image on a recording material at a nip portion even when a plurality of heaters having different light distribution characteristics are incorporated as heating sources into a rotating body using only a non-contact temperature detecting element. Another object of the present invention is to provide an image heating apparatus capable of detecting the winding of the recording material.

  Another object of the present invention is to provide an image forming apparatus in which this image heating device is mounted as a fixing device.

In order to achieve the above object, a typical configuration of the image heating apparatus according to the present invention is as follows.
A rotating body that heats the image on the recording material at the nip,
A heating source disposed inside the rotating body;
Non-contact temperature detection means for measuring the surface temperature of the rotating body heated by the heating source in a non-contact manner;
Rotator driving means for rotating the rotator;
Temperature control means for controlling energization to the heating source so that the surface temperature of the rotating body detected by the non-contact temperature detection means becomes a preset target temperature;
A change in temperature detected by the non-contact temperature detecting means when the rotating body is driven to rotate by the rotating body driving means while the temperature control of the rotating body by the temperature control means is stopped is a preset comparison. A recording material winding detection unit that determines that the recording material is wound around the rotating body when the temperature change period is greater than the value ΔT1 and the period of the temperature change is synchronized with the rotation period of the rotating body;
It is provided with.

In addition, another typical configuration of the image heating apparatus according to the present invention for achieving the above object is as follows:
A rotating body that heats the image on the recording material at the nip,
A heating source disposed inside the rotating body;
Non-contact temperature detection means for measuring the surface temperature of the rotating body heated by the heating source in a non-contact manner;
Rotator driving means for rotating the rotator;
Temperature control means for controlling energization to the heating source so that the surface temperature of the rotating body detected by the non-contact temperature detection means becomes a preset target temperature;
A change in temperature detected by the non-contact temperature detecting means is preset when the rotating body is driven to rotate by the rotating body driving means while temperature control of the rotating body by the temperature control means is stopped. Recording material winding detection means for determining that the recording material is wound around the rotating body when a second comparison value ΔT2 larger than a comparison value ΔT1 of 1 is exceeded;
It is provided with.

According to the present invention, even when a plurality of heaters having different light distribution characteristics are incorporated as heating sources in a rotating body that heats an image on a recording material at a nip portion, only the non-contact temperature detecting element is applied to the rotating body. Can detect the winding of the recording material,
Further, it is possible to detect even when the recording material is not completely wound around the rotating body.

  Next, embodiments of the present invention will be described with reference to the drawings.

(1) Example of Image Forming Apparatus FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus in which an image heating apparatus according to the present invention is mounted as a fixing device. This image forming apparatus is a laser exposure type image recording apparatus (laser beam printer) using an electrophotographic process.

  Reference numeral 101 denotes an apparatus main body, which includes a paper feeding unit that detachably mounts a cassette 102 that stores a sheet-like recording material (recording medium: recording paper, transfer material) S such as paper. The paper feed unit includes a cassette paper presence / absence sensor 103 that detects the presence or absence of the recording material S in the cassette 102, a cassette size sensor 104 that detects the size of the recording material S in the cassette 102, and a feeding material that feeds the recording material S from the cassette 102. A paper roller 105 and the like are provided. The cassette size sensor 104 is composed of a plurality of micro switches.

  Here, in the following description, the upstream side and the downstream side are the upstream side and the downstream side in the recording material conveyance direction.

  A registration roller pair 106 that synchronously conveys the recording material S is provided on the downstream side of the paper feed roller 105. A transfer charging roller 121 is provided on the downstream side of the registration roller pair 106. An electrophotographic process cartridge (hereinafter referred to as a cartridge) 108 that forms a toner image on a photosensitive drum (image carrier) 117 based on laser light from the laser scanner unit 107 is provided above the transfer charging roller 121. It has been. A transfer nip portion is formed by contact between the photosensitive drum 117 and the transfer charging roller 121. The recording material S is introduced to the transfer nip portion at a predetermined control timing by the registration roller pair 106 and is nipped and conveyed, so that the toner image formed on the photosensitive drum 117 is sequentially electrostatically applied on the recording material S. Transcribed. A fixing device 109 (hereinafter, referred to as a fixing device) that thermally fixes the toner image formed on the recording material S is provided downstream of the transfer nip portion. On the downstream side of the fixing device 109, a paper discharge sensor 110 that detects the recording material conveyance state of the paper discharge unit, a paper discharge roller 111 that discharges the recording material S, and a stacking tray 112 on which the recording materials S that have been recorded are stacked. Is provided.

  The laser scanner 107 includes a laser unit 113 that emits a laser beam modulated based on an image signal (image signal VDO) transmitted from the external device 131. Further, it has a polygon mirror 114 for scanning the laser light from the laser unit 113 on the photosensitive drum 117, its drive motor 114a, an imaging lens 115, a mirror 116, and the like.

  In the cartridge 108, image forming process devices such as a photosensitive drum 117, a primary charging roller 119, a developing device 120, and a drum cleaner 122 necessary for a known electrophotographic process are arranged. The cartridge 108 can be attached to and detached from the apparatus main body 101.

  Since the principle and process of forming a toner image on the photosensitive drum 117 are known, the description thereof is omitted. In FIG. 1, arrows at various places indicate the rotation directions of the photosensitive drum 117 and various rollers during the image forming operation.

  The fixing device 109 is a hot pressure roller fixing device. The fixing device 109 will be described in detail in the next section (2).

  Reference numeral 123 denotes a main motor which applies a driving force to the paper feed roller 105 via a clutch 124 and to the registration roller pair 106 via a clutch 125. The main motor 123 also applies driving force to various image forming process devices in the cartridge 108 including the photosensitive drum 117, the fixing device 109, and the paper discharge roller 111.

  An engine controller 126 controls the electrophotographic process by the laser scanner unit 107, the cartridge 108, and the fixing device 109, controls the conveyance of the recording material, and drives the fan 129 that cools the inside of the apparatus main body 101. Reference numeral 127 denotes a video controller, which is connected to an external device 131 such as a computer through a general-purpose interface (Centronics, RS232C, etc.) 130. The video controller 127 expands the image information sent from the general-purpose interface 130 into bit data, and sends the bit data to the engine controller 126 as a VDO signal.

(2) Fixing device 109
2, 3, and 4 are a perspective model view, a longitudinal cross-sectional view, and a transverse cross-sectional view, respectively, of the main part of the fixing device 109.

  The fixing device 109 is a heat roller fixing device. Reference numerals 150 and 180 denote a fixing roller (heat roller, heating roller) and a pressure roller as a pair of rotating bodies that rotate while being pressed against each other to form a nip portion N for nipping and conveying the recording material.

  The fixing roller 150 is, for example, a base made of a metal hollow roller such as aluminum or iron, and a release layer such as a fluororesin formed on the outer peripheral surface thereof. Alternatively, a release layer is formed by interposing a thin elastic rubber layer on a hollow roller of the base. The fixing roller 150 is disposed such that both ends thereof are rotatably supported via a bearing member between side plates of a fixing device casing (not shown). Inside the fixing roller 150, first and second halogen heaters 152 and 153 as heat sources for heating the fixing roller are inserted and arranged. Further, a drive gear G is fitted and fixed to the outer peripheral portion of one end portion of the fixing roller 150.

  The pressure roller 180 is formed by forming a thick elastic layer 180b concentrically and integrally around the outer periphery of the core metal 180a in a roller shape, and forming a release layer 180c such as a fluororesin on the outer peripheral surface of the elastic layer 180b. . The pressure roller 180 is arranged below the fixing roller 150 in parallel with the fixing roller, and both ends of the cored bar 180a are rotatably supported between the side plates of the fixing device housing via a bearing member. It is set up. Further, the pressure roller 180 is brought into pressure contact with the lower surface of the fixing roller 150 with a predetermined pressing force F against the elasticity of the elastic layer 180b by a pressure unit (not shown). Thus, a fixing nip portion N having a preset width in the recording material conveyance direction is formed between the fixing roller 150 and the pressure roller 180.

  The driving force of the main motor 123 that is driven and controlled by the engine controller 126 is transmitted to the drive gear G of the fixing roller 150 via power transmission means (not shown), and the fixing roller 150 is rotated in the clockwise direction of the arrow in FIG. It is rotationally driven at a preset control speed. The pressure roller 180 rotates following the rotation of the fixing roller 150 by the frictional force with the fixing roller 150 at the fixing nip portion N.

  The fixing roller 150 is driven to rotate, and power is supplied to first and second halogen heaters (hereinafter referred to as heaters) 152 and 153 by a heater driving circuit (FIG. 6) described later. The heaters generate heat.

  Due to the heat generated by both the heaters 152 and 153, the fixing roller 150 is heated from the inside to increase the temperature. Then, the surface temperature of the fixing roller 150 is detected by first and second temperature detecting means 154 and 155 described later, and electrical information relating to the detected temperature is input to the engine controller 126. The temperature control function unit 126A (FIG. 6) of the engine controller 126 is configured so that the detected temperature information input from the first and second temperature detecting units 154 and 155 is maintained at a predetermined fixing roller temperature. The power supplied to the heaters 152 and 153 is controlled.

  In this temperature control state, the recording material S carrying the unfixed toner image t is introduced into the fixing device 109 from the image forming mechanism portion side, enters the fixing nip portion N, and is nipped and conveyed. In this nipping and conveying process, the unfixed toner image t on the recording material S is fixed on the surface of the recording material S by the heat and nip pressure of the fixing roller 150.

  In the image forming apparatus of the present embodiment, the recording material S is fed and transported in the apparatus on the basis of the central sheet passing center of the recording material width.

Here, with respect to the recording material S, the width or the paper width is the size of the recording material in the direction orthogonal to the recording material conveyance direction a (FIG. 4) on the plane of the recording material S. In FIGS. 2 and 3, O is the recording material center paper feeding reference (imaginary line). W _A is a sheet passing area width of the maximum width of the recording material can be fed using the apparatus (referred to as a large size recording material). W _B is its paper passing area width of the large size recording material smaller width of the recording medium than (referred to as the small size recording material). W _C is the difference area width between the large size recording material paper feeding area width W _A and the small size recording material paper feeding area width W _B. That is, the non-sheet passing portion region width generated in the recording material conveyance path surface when a small size recording material is passed. Since the recording material paper feeding is Chuodori sheet reference, the non-paper passing area W _C when the fed small size recording material occurs on both sides of the small size recording material paper feeding area width W _B. The non-sheet passing portion region width W _C varies depending on the size of the sheet width of the small size recording material that has been passed.

  FIG. 5 shows the light distribution characteristics in the longitudinal direction of the first and second heaters (halogen heaters) 152 and 153. In the present embodiment, the heater light distribution in the case where the recording material conveyance is set as the central reference is shown. A solid line A is a light distribution characteristic of the first heater 152. The first heater 152 distributes the light distribution largely to the central portion of the fixing roller where the recording material S takes heat away. On the other hand, the dotted line B is the light distribution characteristic of the second heater 153. This second heater 153 is used in combination with the first heater 152 to supply heat to the end of the fixing roller when printing a large size recording material.

  The first temperature detection unit 154 is a temperature detection unit disposed in a non-contact manner with respect to the fixing roller 150 in order to measure the surface temperature of the longitudinal center portion of the fixing roller 150. This temperature detection means is hereinafter referred to as a non-contact thermistor. The non-contact type thermistor 154 is disposed so as to face the non-contact portion of the fixing roller longitudinal central portion that becomes a recording material passing area regardless of whether a recording material having a large or small paper width is passed. That is, the fixing roller portion corresponding to the width of the recording area of the recording material having the minimum sheet width that can be used for the apparatus is disposed in a non-contact manner. In this embodiment, the fixing roller portion substantially corresponding to the recording material center paper passing standard O is disposed so as to face the non-contact. The non-contact thermistor 154 is a main thermistor for adjusting the temperature of the fixing roller 150 to a predetermined temperature.

The second temperature detection unit 155 is a temperature detection unit disposed in contact with the fixing roller 150 in order to measure the surface temperature of the longitudinal end portion of the fixing roller 150. This temperature detection means is hereinafter referred to as a contact type thermistor. The contact-type thermistor 155 is in the outer region of the large size recording material paper feeding area width W _A, at a position closer to the region width W _A side, it is disposed in contact with the fixing roller end portion. This contact type thermistor 155 is a sub-thermistor for monitoring a temperature rise state generated in a non-sheet passing portion region of the fixing roller when a small size recording material is continuously fed.

  The contact type thermistor 155 not only monitors the temperature rise state in the non-sheet passing region as described above, but is also used for temperature control by the second heater 153 for light distribution at the end. Control is performed so that the surface temperature of the fixing roller 150 is made uniform by controlling the first and second heaters 152 and 153, respectively.

(3) Heater Drive Circuit FIG. 6 shows a heater drive circuit, which has two drive circuit sections 51 and 52 for the first and second halogen heaters 152 and 153.

  Reference numeral 1 denotes a commercial power source for electrically connecting the apparatus main body 101. By supplying the electric power of the commercial power source 1 to the first and second heaters 152 and 153 through the AC filter 2, the heaters 152 and 153 generate heat.

  Reference numeral 51 denotes a first drive circuit unit that drives the first heater 152. The triac 7 of the first drive circuit unit 51 is energized and cut off, and the power supply to the first heater 152 is controlled. Resistors 5 and 8 are bias resistors for the triac 7. The phototriac coupler 11 is a device for securing a creepage distance between the primary and secondary, and the spark killer 6 stabilizes the operation of the triac 7. The triac 7 is turned on by energizing the light emitting diode of the phototriac coupler 11. The resistor 9 limits the current flowing through the phototriac coupler 11. The phototriac coupler 11 is turned on / off by the transistor 10. The transistor 10 operates according to an ON signal from the engine controller 126.

  Reference numeral 52 denotes a second drive circuit unit for driving the second heater 153. As in the case of the first drive circuit unit 51, the power supply to the second heater 153 is controlled by the second drive circuit unit 52. In the second drive circuit section 52, 12, 15, and 16 are resistors, 13 is a spark killer, 14 is a triac, 17 is a transistor, and 18 is a phototriac coupler.

  The power of the commercial power source 1 via the AC filter 2 is sent to the engine controller 126 as a pulse signal whose pulse width varies with the voltage of the commercial power source 1 (hereinafter referred to as a ZEROX signal) via the zero-cross detection circuit 23. The

  The engine controller 126 detects the pulse width of the ZEROX signal, and turns on / off the triacs 7 and 14 by phase control or wave number control based on this pulse width.

  The temperature detected by the non-contact thermistor 154 at the longitudinal center of the fixing roller is detected as a voltage divided by the resistor 19 and the non-contact thermistor 154 and is A / D input to the engine controller 126.

  Further, the temperature detected by the contact thermistor 155 at the longitudinal end of the fixing roller is detected as a voltage divided by the resistor 4 and the contact thermistor 155 and A / D input to the engine controller 126.

  The temperature of the fixing roller longitudinal center portion (sheet passing region) detected by the non-contact thermistor 154 is monitored by the engine controller 126 and compared with the reference temperature set in the temperature control function portion 126A of the engine controller 126. . Accordingly, the temperature control function unit 126A determines whether or not the first heater 152 should be energized, and turns on / off the transistor 10 based on the result.

  Similarly, the temperature of the fixing roller longitudinal end portion (non-sheet passing region) detected by the contact type thermistor 155 is monitored by the engine controller 126, and the reference temperature set in the temperature control function unit 126 A of the engine controller 126 is detected. To be compared. Accordingly, the temperature control function unit 126A determines whether or not the second heater 153 should be energized, and turns on / off the transistor 17 based on the result.

  Reference numeral 30 denotes a current transformer, and the primary winding is connected to a common current path from the commercial power source 1 to the first heater 152 and the second heater 153, and the secondary winding is connected to the rectifying bridge 31. It is connected.

  53 is a current detection circuit. The current detection circuit 53 includes a rectifier bridge 31, a smoothing capacitor 32, a load resistor 33, threshold voltage defining resistors 34 and 35, and a comparator 36.

  When a current flows through the first heater 152 or the second heater 153, the same current flows through the primary winding of the current transformer 30, and a predetermined AC voltage is generated at the secondary winding. This AC voltage is full-wave rectified by the rectifier bridge 31, smoothed by the smoothing capacitor 32 and the load resistor 33, and converted into a DC voltage corresponding to the AC voltage.

  Then, the generated DC voltage is compared with a threshold voltage, and if it is equal to or higher than the threshold, the “H” level is input to the input port of the engine controller 126. The threshold value is defined by the threshold voltage defining resistors 34 and 35. The value of the threshold value is determined by the output of the comparator 36 being “H” when a current flows through one of the first and second heaters 152 and 153. "It is set to be level.

  The DC power source Vcc is supplied from a low voltage power source (not shown) (a DC power source is obtained from a commercial AC power source).

  Reference numeral 3 denotes a relay for urgently cutting off the power supply to the first and second heaters 152 and 153. When the temperature detected by the non-contact type or the contact type thermistors 154 and 155 is higher than the reference temperature set in the temperature control function unit 126A of the engine controller 126, the engine controller 126 turns off the relay 3. It becomes control to do. Further, the engine controller 126 is controlled to turn off the relay 3 when a failure of the triacs 7 and 14 is detected.

(4) Detection of Recording Material Wound on Fixing Roller 150 FIGS. 7A and 7B show a state where the recording material S is wound on the fixing roller 150 side. (A) shows a state in which the recording material S is wound around the fixing roller 150 from the leading end, and (B) shows a state in which the recording material S is wound around the fixing roller 150 from the middle thereof.

  In this embodiment, the fixing roller 150 is rotated with the recording material S wound around the fixing roller 150 as described above, and the fixing roller temperature detected by the non-contact thermistor 154 at that time is monitored. When the recording material S is wound around the fixing roller 150, the detected temperature of the non-contact type thermistor 154 depends on the state (wrinkles, number of sheets, etc.) of the recording material S wound around the fixing roller 150 as shown in FIG. , And changes with the rotation period of the fixing roller 150. When the recording material S is not wound around the fixing roller 150, the temperature detected by the non-contact thermistor 154 is almost constant and almost constant.

  In this embodiment, the recording material winding detection function unit 126B of the engine controller 126 detects that the recording material S is wound around the fixing roller 150 by using the fluctuation phenomenon as shown in FIG. It is.

  FIG. 9 is a flowchart of fixing device control including a step of detecting winding of the recording material around the fixing roller 150. The fixing device is controlled by the engine controller 126 and the above-described heater drive circuit (FIG. 6) controlled by the engine controller 126.

  In step S801, when the main power supply is turned on (turned on) to the apparatus main body 101, the main motor 123 is activated, and a warm-up operation of the apparatus main body 101 is started.

  In the fixing device 109, the rotation of the fixing roller 150 is started by the activation of the main motor 123.

  In step S <b> 802, the temperature of the fixing roller 150 is measured by the non-contact thermistor 154. In this case, if the recording material S is not wound around the fixing roller 150, the temperature detected by the non-contact thermistor 154 is the surface temperature of the fixing roller itself. When the recording material S is wound around the fixing roller 150, the temperature detected by the non-contact thermistor 154 is the surface temperature of the recording material S wound around the fixing roller 150.

  When the temperature detected by the non-contact type thermistor 154 is lower than the preset lower limit temperature T3, the first and second heaters 152 and 153 are energized. In step S803, the temperature control of the fixing roller is started so that the temperature detected by the non-contact thermistor 154 is a temperature T5 in a range satisfying T3 <T5 <T4.

  Here, the temperature T4 is a target temperature (temperature control temperature during fixing) set in advance as the surface temperature of the fixing roller 150 during the image forming operation (when the recording material image is heated).

  When the temperature detected by the non-contact thermistor 154 reaches the temperature T5 in S804, the energization of the first and second heaters 152 and 153 is stopped in S805. That is, the temperature control of the fixing roller 150 is stopped.

  In S802, if the temperature detected by the non-contact thermistor 154 is equal to or higher than the lower limit temperature T3, the process proceeds to S805.

  Thereafter, while the fixing roller 150 is continuously driven to rotate in S806, the recording material winding detection function unit 126B of the engine controller 126 detects the temperature ripple detected by the non-contact thermistor 154 during the rotation of the fixing roller 150 in S807. Is detected. If the ripple width is greater than or equal to the preset comparison value ΔT1, then in step S808, the period of the temperature ripple is detected. When the period is synchronized with the rotation period of the fixing roller 150, the recording material winding detection function unit 126B determines that the recording material S is wound around the fixing roller 150 in S809.

  If the recording material winding detection function unit 126B determines that the recording material S is wound around the fixing roller 150, the engine controller 126 stops the image forming operation of the apparatus main body 101 in S810. Then, the display unit 54 of the apparatus main body 101 and the external apparatus 131 connected to the apparatus main body 101 are notified of the occurrence of “wrapping jam”, and the flowchart is ended.

  On the other hand, if the ripple width of the temperature detected by the non-contact thermistor 154 is smaller than the comparison value ΔT1 in S807, the recording material winding detection function unit 126B has the recording material S wound around the fixing roller 150 in S811. Judge that there is no. In addition, even if the detected temperature ripple cycle is not synchronized with the rotation cycle of the fixing roller 150 in S808, the recording material winding detection function unit 126B does not wind the recording material S around the fixing roller 150 in S811. Judge. Subsequently, in S812, a normal operation (image forming operation) is executed.

  In step S813, the engine controller 126 monitors the apparatus main body for failure or jamming during normal operation. If a failure or a jam has occurred, the process proceeds to S802, and the presence or absence of winding of the recording material around the fixing roller 150 is detected.

  By providing the recording material winding detection means as described above, it is possible to detect the winding of the recording material S around the fixing roller (rotating body) 150 only by the non-contact type thermistor (non-contact temperature detection means) 154. .

  Further, immediately before the recording material wrap detection is performed by the recording material wrap detection means as in steps S805 to S808 in FIG. 9, the fixing roller 150 may be preheated as in steps S802 to S804. That is, when the temperature detected by the non-contact thermistor 154 is equal to or lower than a preset lower limit temperature T3, the first and second heaters 152 and 153 are energized to heat the fixing roller 150. The temperature detected by the non-contact thermistor 154 is adjusted to a temperature T5 that is higher than the lower limit temperature T3 and lower than the temperature adjustment temperature T4 during fixing of the fixing roller 150. In this state, recording material winding detection is performed by the recording material winding detection means. Even when the temperature of the fixing roller (rotating body) 150 is low due to the preheating of the fixing roller 150, it is possible to detect a temperature difference occurring in the surface temperature of the fixing roller 150. When the recording material S is wound around the fixing roller 150, it is possible to detect a temperature difference that occurs in the surface temperature of the wound recording material S.

  In the second embodiment, the winding of the recording material S around the fixing roller 150 is determined as follows. In other words, in addition to the ripple information of the detected temperature of the non-contact thermistor 154 described in the first embodiment, when the detected temperature of the non-contact thermistor 154 changes even more than the second comparison value ΔT2 even at 1 degree. Also, it is determined that the recording material S is wound around the fixing roller 150. Since the other image forming apparatus configuration, fixing device configuration, control, and the like are the same as those in the first embodiment, description thereof will be omitted.

  This is not the case where the recording material S is completely wound around the fixing roller 150 as shown in FIG. 10A, but a part Sa of the recording material S is separated from the fixing roller 150 as shown in FIG. It is assumed that there is.

  That is, in this case, when the temperature of the fixing roller 150 is detected by the non-contact type thermistor 154, if the recording material portion Sa separated from the fixing roller 150 approaches or contacts the thermistor 154, the thermistor The temperature of the material portion Sa is measured. Therefore, as shown in FIG. 11, the detected temperature of the non-contact thermistor 154 changes significantly. Since such a state changes as the fixing roller 150 rotates, it does not appear in synchronization with the rotation period of the fixing roller 150.

  Therefore, in the second embodiment, in addition to the first embodiment, even when the temperature detected by the non-contact thermistor 154 is greater than or equal to a preset second comparison value ΔT2, the recording material is transferred to the fixing roller 150. It is judged that S is wound. Here, the second comparison value ΔT2 is a comparison value that is larger than the first comparison value ΔT1 when the comparison value ΔT1 in the first embodiment is used as the first comparison value.

  FIG. 12 is a flowchart of the fixing device control including the step of detecting the winding of the recording material around the fixing roller 150 in the second embodiment. The fixing device is controlled by the engine controller 126 and the heater driving circuit (FIG. 6) controlled by the engine controller 126.

  In step S1101, when the main power supply of the apparatus main body 101 is turned on (on), the main motor 123 is activated and the warming-up operation of the apparatus main body 101 is started.

  In the fixing device 109, the rotation of the fixing roller 150 is started by the activation of the main motor 123.

  In step S1102, the temperature of the fixing roller 150 is measured by the non-contact thermistor 154. In this case, if the recording material S is not wound around the fixing roller 150, the temperature detected by the non-contact thermistor 154 is the surface temperature of the fixing roller itself. When the recording material S is wound around the fixing roller 150, the temperature detected by the non-contact thermistor 154 is the surface temperature of the recording material S wound around the fixing roller 150.

  When the temperature detected by the non-contact thermistor 154 is lower than a preset lower limit temperature T3, the first and second heaters 152 and 153 are energized. In step S1103, temperature control of the fixing roller is started so that the temperature detected by the non-contact thermistor 154 is a temperature T5 in a range satisfying T3 <T5 <T4.

  Here, the temperature T4 is the surface temperature of the fixing roller 150 during the image forming operation (when the recording material image is heated) (temperature adjustment temperature during fixing).

  When the temperature detected by the non-contact thermistor 154 reaches the temperature T5 in S1104, the energization of the first and second heaters 152 and 153 is stopped in S1105. That is, the temperature control of the fixing roller 150 is stopped.

  In S1102, if the temperature detected by the non-contact thermistor 154 is equal to or higher than the lower limit temperature T3, the process proceeds to S1105.

  Thereafter, while the fixing roller 150 is continuously rotated in S1106, in S1107, the recording material winding detection function unit 126B of the engine controller 126 changes the temperature detected by the non-contact thermistor 154 during the rotation process of the fixing roller 150. Is detected.

  If the temperature change is smaller than the second comparison value ΔT2 (> ΔT1), the temperature ripple of the temperature detected by the non-contact thermistor 154 is detected in S1108. If the ripple width is larger than the first comparison value ΔT1, the temperature ripple period is detected in S1109. When the period is synchronized with the rotation period of the fixing roller 150, the recording material winding detection function unit 126B determines that the recording material S is wound around the fixing roller 150 in S1110.

  If the recording material winding detection function unit 126B determines that the recording material S is wound around the fixing roller 150, the engine controller 126 stops the image forming operation of the apparatus main body 101 in S1111. Then, the display unit 54 of the apparatus main body 101 and the external apparatus 131 connected to the apparatus main body 101 are notified of the occurrence of “wrapping jam”, and the flowchart is ended.

  In S1107, when the change in temperature detected by the non-contact thermistor 154 is equal to or greater than the second comparison value ΔT2, the process proceeds to S1110, and the flowchart is terminated through S1111.

  On the other hand, if the ripple width of the temperature detected by the non-contact thermistor 154 is smaller than the first comparison value ΔT1 in S1108, the recording material winding detection function unit 126B causes the recording material S to be fed to the fixing roller 150 in S1112. Judge that it is not wrapped. In addition, even when the detected temperature ripple cycle is not synchronized with the rotation cycle of the fixing roller 150 in S1109, the recording material winding detection function unit 126B does not wind the recording material S around the fixing roller 150 in S1112. Judge. Subsequently, in S1113, a normal operation (image forming operation) is executed.

  Further, in S1114, the engine controller 126 monitors a failure of the apparatus main body and occurrence of a jam during normal operation. If a failure or jam has occurred, the process advances to step S1102 to detect whether the recording material is wound around the fixing roller 150.

  By providing the recording material winding detection means as described above, it is possible to detect the winding of the recording material S around the fixing roller (rotating body) 150 only by the non-contact type thermistor (non-contact temperature detection means) 154. . Further, it is possible to detect even when the recording material S is not completely wound around the fixing roller 150.

  Further, just before the recording material winding detection is performed by the recording material winding detection unit as in steps S1105 to S1109 in FIG. 12, the fixing roller 150 may be preheated as in steps S1102 to S1104. That is, when the temperature detected by the non-contact thermistor 154 is equal to or lower than a preset lower limit temperature T3, the first and second heaters 152 and 153 are energized to heat the fixing roller 150. The temperature detected by the non-contact thermistor 154 is adjusted to a temperature T5 that is higher than the lower limit temperature T3 and lower than the temperature adjustment temperature T4 during fixing of the fixing roller 150. In this state, recording material winding detection is performed by the recording material winding detection means. Even when the temperature of the fixing roller (rotating body) 150 is low due to the preheating of the fixing roller 150, it is possible to detect a temperature difference occurring in the surface temperature of the fixing roller 150. When the recording material S is wound around the fixing roller 150, it is possible to detect a temperature difference that occurs in the surface temperature of the wound recording material S.

  1) In the first and second embodiments, the rotation speed of the fixing roller 150 when the recording material winding detection unit detects the recording material winding (S806 in FIG. 9 and S1106 in FIG. 12) is the same as that during the image forming operation (recording material). It may be equal to or less than the rotation speed during image heating. As a result, the detection accuracy of the surface temperature of the fixing roller 150 can be improved. Even when the recording material S is wound around the fixing roller 150, the detection accuracy of the surface temperature of the wound recording material S can be improved.

  2) The recording material wrap detection by the recording material wrap detection means is executed at any one, two, or all after the occurrence of a failure of the device and the occurrence of a jam when the apparatus is turned on. It is good to. Thereby, only when there is a possibility that the recording material is wound around the fixing roller 150, the recording material winding detection sequence is performed by the recording material winding detection means, and therefore, the control can be simplified.

  3) When recording material winding is detected by the recording material winding detection means, the occurrence of a recording material winding jam is notified and a control sequence for stopping the operation of the apparatus is executed. Thereby, it is possible to prevent the operation of the apparatus in a state where the recording material S is wound around the fixing roller 150.

  4) The image forming apparatus and the fixing device 109 are not limited to those in which the sheet passing standard of the recording material is the central sheet passing standard, and may be an apparatus that is a one-sided sheet passing standard.

  5) The heating source disposed inside the fixing roller 150 is not limited to the halogen heater. A ceramic heater, electromagnetic induction heating means, high-frequency heating means, or the like may be used. The central part and the end part of the fixing roller may be the same heating body or a heating body having the same calorific value.

  6) The heating rotator is not limited to the fixing roller 150, and may be a cylindrical or endless film member or belt member.

  7) The pressure rotating body is not limited to the pressure roller 180, and may be a cylindrical or endless film member or belt member. Moreover, it is also possible to adopt a device configuration in which a heating source is also provided inside the pressure rotating body for heating. In this case, it is possible to adopt an apparatus configuration in which a recording material winding jam around the pressure rotator is detected by a recording material winding detection unit similar to the case of the fixing roller 150.

Schematic diagram of an image forming apparatus in Embodiment 1. The perspective model figure of the principal part of the fixing device in Example 1. Longitudinal sectional view of the main part of the fuser Cross section of the main part of the fuser Light distribution characteristic graph of first and second halogen heaters Driving circuit for first and second halogen heaters (A) and (B) are schematic views showing a state where the recording material is wound around the fixing roller, respectively. Schematic diagram of temperature change detected by non-contact thermistor when recording material is wound around fixing roller Flowchart of fixing device control including a step of detecting winding of the recording material around the fixing roller. (A) and (B) are schematic views showing a state where the recording material is wound around the fixing roller (Example 2). Schematic diagram of change in detected temperature of non-contact thermistor when recording material is wound around fixing roller (Example 2) Flowchart of fixing device control including step of detecting winding of recording material around fixing roller (second embodiment)

Explanation of symbols

109: fixing device 126: engine controller 150: fixing roller 152, 153: halogen heater 154: non-contact type thermistor 155: contact type thermistor 180: pressure roller 3: relay 7, 14: triac 30: current transformer

Claims (7)

A rotating body that heats the image on the recording material at the nip,
A heating source disposed inside the rotating body;
Non-contact temperature detection means for measuring the surface temperature of the rotating body heated by the heating source in a non-contact manner;
Rotator driving means for rotating the rotator;
Temperature control means for controlling energization to the heating source so that the surface temperature of the rotating body detected by the non-contact temperature detection means becomes a preset target temperature;
A change in temperature detected by the non-contact temperature detecting means when the rotating body is driven to rotate by the rotating body driving means while the temperature control of the rotating body by the temperature control means is stopped is a preset comparison. A recording material winding detection unit that determines that the recording material is wound around the rotating body when the temperature change period is greater than the value ΔT1 and the period of the temperature change is synchronized with the rotation period of the rotating body;
An image heating apparatus comprising: A rotating body that heats the image on the recording material at the nip,
A heating source disposed inside the rotating body;
Non-contact temperature detection means for measuring the surface temperature of the rotating body heated by the heating source in a non-contact manner;
Rotator driving means for rotating the rotator;
Temperature control means for controlling energization to the heating source so that the surface temperature of the rotating body detected by the non-contact temperature detection means becomes a preset target temperature;
A change in temperature detected by the non-contact temperature detecting means is preset when the rotating body is driven to rotate by the rotating body driving means while temperature control of the rotating body by the temperature control means is stopped. Recording material winding detection means for determining that the recording material is wound around the rotating body when a second comparison value ΔT2 larger than a comparison value ΔT1 of 1 is exceeded;
An image heating apparatus comprising:   Immediately before performing the recording material winding detection by the recording material winding detection means, if the temperature detected by the non-contact temperature detection means is equal to or lower than a preset lower limit temperature T3, the heating source is energized to After adjusting the temperature detected by the contact temperature detecting means to a temperature T5 that is higher than the lower limit temperature T3 and lower than the target temperature T4 that is preset as the surface temperature of the rotating body at the time of heating the recording material image. The image heating apparatus according to claim 1, wherein the recording material wrap detection is performed by the recording material wrap detection unit.   When the recording material winding detection unit performs the recording material winding detection, the rotational speed of the rotating body driven by the rotating body driving unit is the rotational body driven by the rotating body driving unit during recording material image heating. The image heating apparatus according to claim 1, wherein the image heating apparatus is equal to or less than the rotation speed of the image heating apparatus.   The recording material wrap detection by the recording material wrap detection means is performed by any one, two, or all of the following when the device is turned on, after the failure of the device, or after the occurrence of a jam. The image heating apparatus according to claim 1, wherein the image heating apparatus is characterized in that:   6. A control sequence for notifying the occurrence of a recording material winding jam and stopping the operation of the apparatus when recording material winding is detected by the recording material winding detection means. An image heating apparatus according to claim 1.   An image forming apparatus comprising: an image forming unit that forms an unfixed image on a recording material; and a fixing unit that heat-fixes the image on the recording material, wherein the fixing unit is any one of claims 1 to 6. An image forming apparatus according to claim 1.

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