JP6991727B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus such as a copying machine or a printer.

An image forming apparatus such as a copying machine or a printer is provided with a fixing device. In the fixing device shown in Patent Document 1, a heat generating layer is provided on a cylindrical film, and the film itself is heated by supplying power to the heat generating layer. This fixes the toner image on the recording material. Such a surface heat generation type fixing device has a short start-up time from turning on the power to reaching a fixable temperature, and can increase the start-up speed.

Japanese Unexamined Patent Publication No. 2007-272223

In Patent Document 1, the film in contact with the recording material generates heat. Therefore, if power is supplied to the heat generating layer while the recording material is retained in the fixing device, the temperature of the recording material may become high and heat may be fused to the film. When a temperature detection sensor is provided on the outer peripheral surface of the film, foreign matter such as a recording material may intervene between the temperature detection sensor and the film. In this case, accurate temperature control of the film cannot be performed.

The present invention solves the above-mentioned problems, and an object of the present invention is to provide an image forming apparatus capable of determining a state based on the detection results of a plurality of temperature detecting means.

A typical configuration of the image forming apparatus according to the present invention for achieving the above object is an image forming apparatus having an image forming means for forming an image on a recording material, which comprises a tubular film containing a heating element and a tubular film. A first temperature detecting means that is non-contactly arranged at a position facing the film on the outer peripheral surface side of the film and detects the temperature of the heating element from the outer peripheral surface side , and the temperature detecting means on the inner peripheral surface side of the film. Based on the detection results of the second temperature detecting means , which is arranged in contact with the position facing the film and detects the temperature of the heating element from the inner peripheral surface side , and the first and second temperature detecting means. The first temperature detecting means has a determination means for determining the state of the image forming apparatus, and the first temperature detecting means has higher responsiveness than the second temperature detecting means, and when power is supplied to the heating element. When the temperature detected by the first temperature detecting means rises and the temperature detected by the second temperature detecting means rises in the first state, the determining means determines the first temperature. If the temperature detected by the means does not reach the threshold temperature , which is an abnormal temperature that does not reach during printing, it is determined to be in a normal state, and if the temperature reaches the threshold temperature , the film is slipping. When it is determined that the temperature is abnormal and power is supplied to the heating element, the temperature detected by the second temperature detecting means rises higher than the temperature detected by the first temperature detecting means. When the temperature is high and the difference between the temperature detected by the first temperature detecting means and the temperature detected by the second temperature detecting means becomes larger than a predetermined value , the determination means Determines that the recording material is in the second abnormal state of being wound around the film, and when power is supplied to the heating element, the temperature detected by the first temperature detecting means does not rise and When the third state in which the temperature detected by the second temperature detecting means does not rise is reached, the determining means determines that it is a third abnormal state, which is a failure of the feeding unit .

According to the present invention, the state of the image forming apparatus can be determined based on the detection results of the plurality of temperature detecting means.

It is sectional drawing which shows the structure of the image forming apparatus which concerns on this invention. It is a perspective explanatory drawing which shows the structure of the fixing device of 1st Embodiment. It is sectional drawing which shows the structure of the fixing device of 1st Embodiment. It is sectional drawing which shows the structure of the temperature detecting means which comes into contact with the inner peripheral surface of the film of the fixing apparatus of 1st Embodiment. It is a figure which shows the detection result of the temperature detecting means which comes into contact with the inner peripheral surface of a film with respect to the feeding operation of the fixing device of 1st Embodiment. It is a flowchart which shows the control of the fixing device of 1st Embodiment. It is a perspective explanatory drawing which shows the structure of the fixing device of 2nd Embodiment. It is sectional drawing which shows the structure of the fixing device of 2nd Embodiment. It is a flowchart which shows the control of the fixing device of 2nd Embodiment. It is a figure which shows the temperature change of the temperature detecting means provided in contact with or facing the inner peripheral surface of a film at the time of raising the fixing temperature of the fixing apparatus of 2nd Embodiment. It is a figure which shows the temperature change of the temperature detecting means provided in contact with or facing the inner peripheral surface of a film at the time of winding a recording material of the fixing apparatus of 2nd Embodiment. The temperature change of the temperature detecting means provided in contact with or facing the inner peripheral surface of the film when the heat generating layer is energized when the rotation of the film of the fixing device of the second embodiment is stopped is shown. It is a figure.

An embodiment of the image forming apparatus according to the present invention will be specifically described with reference to the drawings.

[First Embodiment]
The configuration of the first embodiment of the image forming apparatus according to the present invention will be described with reference to FIGS. 1 to 6.

<Image forming device>
First, the configuration of the image forming apparatus 110 according to the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional explanatory view showing the configuration of the image forming apparatus 110 according to the present invention. The image forming apparatus 110 shown in FIG. 1 shows an example of an electrophotographic laser printer. The image forming apparatus 110 shown in FIG. 1 is a process cartridge serving as an image forming means for forming an image on a recording material P based on an image exposed and scanned on the surface of a photosensitive drum 103 serving as an image carrier by an optical scanning apparatus 101. 102 is provided.

The image forming apparatus 110 shown in FIG. 1 emits a laser luminous flux L based on the obtained image information by an optical scanning apparatus 101 serving as an exposure means, and a photosensitive drum 103 as an image carrier built in the process cartridge 102. Irradiate on the surface. The process cartridge 102 is configured as an image forming means for forming an image on the recording material P. The process cartridge 102 is integrally provided with a photosensitive drum 103, a charging roller 21 as a charging means as an image forming process means acting on the photosensitive drum 103, a developing device 22 as a developing means, a cleaner 25 as a cleaning means, and the like. Has been done. The process cartridge 102 is detachably provided with respect to the main body of the image forming apparatus 110.

The surface of the photosensitive drum 103 that rotates clockwise in FIG. 1 is uniformly charged by the charging roller 21. The surface of the uniformly charged photosensitive drum 103 is exposed and scanned by the optical scanning device 101 with the laser luminous flux L corresponding to the image information. As a result, an electrostatic latent image corresponding to the image information is formed on the surface of the photosensitive drum 103. Toner (developer) is supplied to the electrostatic latent image formed on the surface of the photosensitive drum 103 by a developing roller 22a which is a developer carrier provided in the developing apparatus 22, and the toner image T is developed.

On the other hand, the recording material P housed in the feeding cassette 104 is fed out by the feeding roller 105, and is separated and fed one by one in cooperation with the separation roller 23. Further, the tip portion of the recording material P is attached to the nip portion of the resist roller 24 which has been pinched and transported by the transport roller 106 and stopped, and the skew of the recording material P is corrected.

The resist roller 24 moves in synchronization with the timing at which the toner image T formed on the surface of the photosensitive drum 103 reaches the transfer nip portion N1 formed by the surface of the photosensitive drum 103 and the transfer roller 107 serving as a transfer means. Rotate. As a result, the recording material P is sandwiched by the resist roller 24 and conveyed to the transfer nip portion N1. A transfer bias is applied to the transfer roller 107 by a transfer bias power supply (not shown), and the toner image T formed on the surface of the photosensitive drum 103 is transferred to the recording material P. The residual toner remaining on the surface of the photosensitive drum 103 after transfer is removed by the cleaner 25 and recovered.

The recording material P on which the unfixed toner image T is formed is sandwiched between the photosensitive drum 103 and the transfer roller 107 and conveyed to the fixing device 108 as the fixing means. In the process of being sandwiched and conveyed by the fixing unit 26 provided in the fixing device 108 and the pressure roller 3, the toner image T is thermally melted by being heated and pressurized, and is heat-fixed to the recording material P. The recording material P sandwiched and conveyed by the fixing unit 26 of the fixing device 108 and the pressure roller 3 is discharged onto a discharge tray 27 provided outside the machine by the discharge roller 109. The pressurizing roller 3 is rotationally driven by a fixing motor 30 which is a drive source shown in FIG.

In the present embodiment, a charging roller 21 as a charging means as an image forming process means acting on the photosensitive drum 103 and a developing device 22 as a developing means are provided integrally with the photosensitive drum 103 inside the process cartridge 102. In addition, each image forming process means may be configured separately from the photosensitive drum 103.

<Fixing device>
Next, the configuration of the fixing device 108 of the present embodiment will be described with reference to FIGS. 2 to 4. FIG. 2 is a perspective explanatory view showing the configuration of the fixing device 108 of the present embodiment. FIG. 3 is a cross-sectional explanatory view showing the configuration of the fixing device 108 of the present embodiment. FIG. 4 is a cross-sectional explanatory view showing a configuration of a temperature detecting means that contacts the outer peripheral surface 1a and the inner peripheral surface 1b of the film of the fixing device 108 of the present embodiment, respectively.

As shown in FIGS. 2 and 3, the fixing device 108 of the present embodiment includes a cylindrical film 1 as a heating element, a guide member 2 that rotatably supports the film 1, and an outer peripheral surface 1a of the film 1. It is configured to have a pressure roller 3 forming a fixing nip portion N2 together with the pressure roller 3. Further, as shown in FIG. 4, a thermistor 5 is provided as a first temperature detecting means for slidably contacting the outer peripheral surface 1a of the film 1 and detecting the temperature of the outer peripheral surface 1a of the film 1. .. Further, a thermistor 6 is provided as a second temperature detecting means for slidably contacting the inner peripheral surface 1b of the film 1 and detecting the temperature of the inner peripheral surface 1b of the film 1.

The thermistor 5 (first temperature detecting means) detects the temperature of the film 1 (heat generator) from one side. The thermistor 6 (second temperature detecting means) detects the temperature of the film 1 (heat generator) from the other surface. The thermistor 5 (first temperature detecting means) is provided on the outer peripheral surface 1a side (outer peripheral surface side) of the film 1 (cylindrical film). The thermistor 6 (second temperature detecting means) is provided on the inner peripheral surface 1b side (inner peripheral surface side) of the film 1 (cylindrical film). The thermistors 5 and 6 are connected to a control unit 28 which is a control means.

The recording material P carrying the toner image T sandwiched and conveyed by the surface of the photosensitive drum 103 shown in FIG. 1 and the transfer roller 107 is conveyed from the right side of FIG. 3 to the fixing nip portion N2. The toner image T is thermally melted by being heated and pressurized in the fixing nip portion N2, and is heat-fixed to the recording material P.

<Heating element>
The film 1 serving as a heating element has a heat generating layer 13 as a base layer that generates heat by energization. The heat generating layer 13 is formed of a resin such as polyimide, and a conductive filler such as carbon is dispersed therein. A coating layer 14 is provided on the outer peripheral surface of the heat generating layer 13. The heat generating layer 13 of the present embodiment uses a polyimide resin in which carbon black as a conductive filler is dispersed. The coating layer 14 uses PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer) having good releasability. The film 1 (heating element) is configured as a tubular film having a heat generating layer 13 that generates heat when energized.

<Guide member>
The guide member 2 is formed of a heat-resistant resin such as a polymer resin, and plays a role of guiding the rotation of the film 1. Both ends of the guide member 2 in the longitudinal direction (left-right direction in FIG. 2) engage with the reinforcing stays 4 supported by the device frame. By an urging means (not shown), both ends of the reinforcing stay 4 in the longitudinal direction are urged so that the guide member 2 presses against the pressure roller 3 via the film 1. As a result, the film 1 is driven by the rotation of the pressure roller 3.

The reinforcing stay 4 is made of a rigid material such as iron, stainless steel, and gin-coated steel plate. As a result, the urging force received at both ends of the reinforcing stay 4 in the longitudinal direction by the urging means (not shown) is uniformly transmitted in the longitudinal direction of the guide member 2. The guide member 2 of the present embodiment uses a liquid crystal polymer, and the reinforcing stay 4 uses a gin-coated steel plate.

<Pressurized roller>
The pressure roller 3 serving as a rotating body includes a core metal 10, an elastic layer 11, and a mold release layer 12. The pressure roller 3 of the present embodiment forms a silicone rubber layer as an elastic layer 11 on the outer peripheral surface of an iron core metal 10 having an outer diameter of 11 mm. Further, a PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer) tube having an electrical insulating property is coated on the outer peripheral surface of the elastic layer 11 as a release layer 12.

<Thermistor>
The thermistor 5 is slidably provided on the outer peripheral surface 1a of the tubular film 1 and detects the temperature of the outer peripheral surface 1a of the film 1. In the present embodiment, the thermistor 5 which is the first temperature detecting means detects the temperature of the outer peripheral surface 1a in contact with the recording material P of the film 1 which is a heating element. The thermistor 5 of the present embodiment is provided so as to face substantially the central portion of the film 1 in the axial direction (left-right direction in FIG. 2). In the image forming apparatus 110 of the present embodiment, the recording material P is conveyed with reference to the center in the longitudinal direction (left-right direction in FIG. 2) of the fixing nip portion N2. As a result, the thermistor 5 is arranged within the range of the minimum width of the recording material P passing through the fixing nip portion N2.

The thermistor 5 (first temperature detecting means) detects the temperature of the surface of the film 1 (heat generating element) facing the recording material P, and the thermistor 5 (first temperature detecting means) is attached to the image forming apparatus 110. It is provided within the range through which the recording material P having the minimum width to be used passes. By arranging the thermistor 5 within the range of the minimum width of the recording material P, it is possible to detect the winding of the recording material P with respect to the outer peripheral surface 1a of the film 1 regardless of the size of the recording material P that can be used by the image forming apparatus 110. Is possible.

The thermistor 6 is slidably provided on the inner peripheral surface 1b of the tubular film 1 and detects the temperature of the inner peripheral surface 1b of the film 1. The thermistor 6 of the present embodiment is provided at a position facing the thermistor 5 with the film 1 interposed therebetween. The thermistor 5 (first temperature detecting means) and the thermistor 6 (second temperature detecting means) face each other with the film 1 (heat generating element) interposed therebetween.

As shown in FIG. 4, the thermistors 5 and 6 detect the temperature at the same position on the outer peripheral surface 1a and the inner peripheral surface 1b of the film 1, respectively. The thermistors 5 and 6 are respectively configured as contact-type temperature detecting means. As a result, the detection temperature difference between the thermistors 5 and 6 becomes small in normal times except when an abnormality such as when the recording material P is wound around the outer peripheral surface 1a of the film 1 is excluded. As a result, it is possible to accurately determine when an abnormality occurs.

Thermistors 5 and 6 are composed of the same element. The thermistors 5 and 6 each include a thermistor element 15 and a conductive arm 16. As shown in FIG. 4, the thermistor element 15 is configured by winding the outer periphery of the temperature sensitive element 19 with Kapton tape 18. The Kapton tape 18 is a tape for electrical insulation and heat-resistant masking, which is made of Kapton (polyimide film) having excellent heat / cold resistance, mechanical properties, electrical properties, chemical resistance, etc. and coated with a silicone-based adhesive. It maintains excellent mechanical, electrical, physical and chemical properties in a wide temperature range from low temperature to high temperature. Therefore, the Kapton tape 18 plays a role of protecting the temperature sensitive element 19 from rubbing between the outer peripheral surface 1a and the inner peripheral surface 1b of the film 1.

The arm 16 presses the thermistor element 15 against the outer peripheral surface 1a and the inner peripheral surface 1b of the film 1, respectively. Even when the rotation trajectory of the flexible film 1 changes, each thermistor element 15 is maintained in a state of being in stable contact with the outer peripheral surface 1a and the inner peripheral surface 1b of the film 1.

Further, the conductive arm 16 also serves as a signal line, and the temperature sensitive element 19 and the arm 16 are connected by a conductive Dumet wire 20. The jumet wire 20 is made by coating an alloy of iron and nickel with copper. In the present embodiment, the thermistors 5 and 6 are arranged at the same position on the outer peripheral surface 1a and the inner peripheral surface 1b of the film 1 in order to accurately determine the abnormality, but the thermistors 5 and 6 do not necessarily have to be arranged at the same position.

When the recording material P passes through the fixing nip portion N2, the film 1 is deprived of heat by the recording material P. Therefore, the temperature of the film 1 in the passing region Ap (central portion in the present embodiment) of the recording material P in the fixing nip portion N2 is the non-passing region An (both ends in the present embodiment) of the recording material P in the fixing nip portion N2. It may be lower than the temperature of the film 1.

It is desirable that the changes in the detection results of the thermistors 5 and 6 are the same in normal times except when the recording material P is wound around the outer peripheral surface 1a of the film 1 or the like. Therefore, it is preferable that the thermistor 6 is also arranged within the range of the minimum width of the recording material P passing through the fixing nip portion N2 like the thermistor 5.

The thermistors 5 and 6 of the present embodiment are provided on the downstream side in the rotation direction (clockwise direction in FIG. 3) of the film 1 with respect to the fixing nip portion N2 formed by the outer peripheral surface 1a of the film 1 and the pressure roller 3. This is just one example. The arrangement positions of the thermistors 5 and 6 are not limited to this, and can be arranged at various positions on the outer peripheral surface 1a and the inner peripheral surface 1b of the film 1.

<Power supply member>
As shown in FIG. 2, both ends of the heat generating layer 13 provided on the inner peripheral surface 1b side of the film 1 in the longitudinal direction (left-right direction in FIG. 2), and further on the inner peripheral surface 1b side of the heat generating layer 13. A pair of conductive layers 7 are provided respectively. The conductive layer 7 is formed by coating the silver paste over the entire circumferential direction (one circumference) of the film 1. Each conductive layer 7 is provided with a pair of feeding members 9 made of a conductive stainless steel sheet metal so as to be electrically in contact with each other and slidably.

An AC power supply 29 is connected to the pair of power feeding members 9 via an electric cable 8. By applying an AC voltage from the AC power supply 29 to the pair of power feeding members 9, power is supplied to the heat generating layer 13 via the conductive layer 7 provided on the inner peripheral surface 1b side of the film 1, and an AC current is applied to the heat generating layer 13. It flows and generates heat due to Joule heat. In the present embodiment, the AC voltage applied from the AC power supply 29 to the pair of feeding members 9 is set to 100V. The pair of feeding members 9 are pressed toward the pressure roller 3 with the film 1 interposed therebetween by an urging means (not shown).

The surface resistance value of the conductive layer 7 is set to a value smaller than the surface resistance value of the heat generating layer 13. In the present embodiment, the electric resistance value between the pair of feeding members 9 in the longitudinal direction of the film 1 (left-right direction in FIG. 2) is 20Ω. On the other hand, the electric resistance value between the feeding member 9 and the conductive layer 7 in the thickness direction of the film 1 is 1.8Ω. When the heat generating layer 13 is directly fed from the pair of feeding members 9 without forming the conductive layer 7 on the inner peripheral surface 1b of the heating layer 13, the pair of feeding members 9 in the longitudinal direction of the film 1 The electrical resistance value between them is 42Ω.

As in the present embodiment, the conductive layer 7 is formed on the inner peripheral surface 1b of the heat generating layer 13 at both ends in the longitudinal direction (left-right direction in FIG. 2) of the film 1 over the entire circumferential direction of the film 1. As a result, it can be seen that the alternating current applied from the alternating current power supply 29 to the pair of feeding members 9 easily flows from the feeding member 9 via the conductive layer 7 in the rotation direction of the heat generating layer 13. In order to facilitate the adhesion between the conductive layer 7 and the heat generating layer 13, an intermediate layer (not shown) having conductivity may be interposed between the conductive layer 7 and the heat generating layer 13.

<Judgment of the state of the image forming apparatus>
Next, the principle of determining the state of the image forming apparatus 110 using the temperature detection results detected by the thermistors 5 and 6 of the present embodiment will be described with reference to FIG. Power is supplied from the AC power supply 29 to the heat generating layer 13 provided on the inner peripheral surface 1b side of the film 1 via the pair of power feeding members 9 and the conductive layer 7. At that time, FIG. 5 is a diagram showing whether or not the temperature detection result detected by the thermistors 5 and 6 that abut and slide on the outer peripheral surface 1a and the inner peripheral surface 1b of the film 1 changes. "○" shown in FIG. 5 indicates that the thermistors 5 and 6 detected the temperature rise, and "x" indicates that the thermistors 5 and 6 did not detect the temperature rise or the detection result hardly changed. Show that.

In normal times other than abnormal times such as when the recording material P is wound around the outer peripheral surface 1a of the film 1, the thermistors 5 and 6 change the detection result in response to the temperature change of the film 1. On the other hand, when the recording material P is wound around the outer peripheral surface 1a of the film 1, the recording material P such as paper is between the thermistor 5 that abuts and slides on the outer peripheral surface 1a of the film 1 and the outer peripheral surface 1a of the film 1. Intervenes. Therefore, the heat of the outer peripheral surface 1a of the film 1 is taken away by the recording material P, and the temperature detected by the thermistor 5 decreases. Therefore, the thermistor 5 cannot accurately detect the temperature of the outer peripheral surface 1a of the film 1.

On the other hand, the thermistor 6 maintains a state of abutting and sliding against the inner peripheral surface 1b of the film 1 even when the recording material P is wound around the outer peripheral surface 1a of the film 1. Therefore, the temperature detected by the thermistor 6 changes in response to the temperature change of the inner peripheral surface 1b of the film 1. Even when a foreign substance other than the recording material P is interposed between the thermistor 5 and the outer peripheral surface 1a of the film 1, each thermistor 5 and 6 has the same detection result as when the recording material P is wound around the outer peripheral surface 1a of the film 1. Is shown.

Further, if power is not normally supplied to the heat generating layer 13 provided on the inner peripheral surface 1b side of the film 1 due to an abnormality such as disconnection of the electric circuit between the AC power supply 29 and the heat generating layer 13, the film There is no temperature change between the outer peripheral surface 1a and the inner peripheral surface 1b of 1. Therefore, the detection results of the thermistors 5 and 6 do not change.

As shown in FIG. 5, a normal time excluding an abnormal time such as when the recording material P is wound around the outer peripheral surface 1a of the film 1 is considered. Further, the time when the recording material P is wound around the outer peripheral surface 1a of the film 1 is taken into consideration. Furthermore, consider the case of power supply failure due to device abnormality such as disconnection. There is a difference in the temperature detection results by the thermistors 5 and 6 during these normal times, winding times, and power supply failure. The detection results of the thermistor 5 that abuts and slides on the outer peripheral surface 1a of the film 1 and the thermistor 6 that abuts and slides on the inner peripheral surface 1b of the film 1 are used. As a result, it is possible to discriminate between the time when the recording material P is wound around the outer peripheral surface 1a of the film 1 and the time when the power supply fails due to a device abnormality such as disconnection.

Next, a control method of the fixing device 108 of the present embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing a control method of the fixing device 108 of the present embodiment. In FIG. 6, “◯” indicates that the thermistors 5 and 6 have detected the temperature rise of the film 1, and “×” indicates that the thermistors 5 and 6 do not detect the temperature rise of the film 1 or the detection result. Shows that there is almost no change.

When the printing operation of the image forming apparatus 110 is started in step S1, in step S2, the control unit 28 serving as a control means rotationally drives the fixing motor 30 and controls the AC power supply 29 to control the heat generating layer of the film 1. An alternating current is applied to 13. After that, in step S3, the control unit 28 acquires the temperature detection results of the thermistors 5 and 6.

If both thermistors 5 and 6 detect an increase in the temperature of the film 1 in step S3, the control unit 28 determines that there is no abnormality and proceeds to step S4. In step S4, the control unit 28 controls the AC power supply 29 to apply an AC current to the heat generating layer 13 of the film 1 to perform normal temperature control to perform printing.

After that, in step S5, the control unit 28 determines whether or not the accepted print job is completed, and if the accepted print job is completed, proceeds to step S6. The steps S4 and S5 are repeated while the received print job is not completed. In step S6, the control unit 28 turns off the alternating current applied from the alternating current power supply 29 to the heat generating layer 13 of the film 1, turns off the rotational drive of the fixing motor 30, and stops the rotation of the pressurizing roller 3. After that, the process proceeds to step S7 to end the operation.

In step S3, when the detection result of the thermistor 5 hardly changes (“x”) and the thermistor 6 detects a temperature rise of “◯”, the control unit 28 records on the outer peripheral surface 1a of the film 1. It is determined that the material P is wound. When printing is performed while the recording material P is wound around the outer peripheral surface 1a of the film 1, heat is not sufficiently transferred to the toner image supported on the recording material P, and the toner image is discharged without being fixed, resulting in image defects.

Further, if heating is repeated while the recording material P is wound around the outer peripheral surface 1a of the film 1, the recording material P may be heat-sealed to the outer peripheral surface 1a of the film 1. Therefore, in step S3, when the control unit 28 determines that the recording material P is wound around the outer peripheral surface 1a of the film 1, the control unit 28 proceeds to step S8. In step S8, the control unit 28 controls the AC power supply 29 to cut off (OFF) the AC current applied to the heat generating layer 13 of the film 1, turns off the fixing motor 30, and stops the rotation of the pressurizing roller 3. do.

After that, the process proceeds to step S9 to indicate that the recording material P is wound around the outer peripheral surface 1a of the film 1 on a display panel provided in an operation unit (not shown) of the image forming apparatus 110. As a result, an error display is performed to notify the user and notify the user to remove the recording material P wrapped around the outer peripheral surface 1a of the film 1. The control unit 28 (determining means) is between the thermistor 5 (first temperature detecting means) and the film 1 (heating element) based on the detection results of the thermistors 5 and 6 (first and second temperature detecting means). It can be determined that foreign matter is accumulated in the area. After that, the process proceeds to step S7 to end the operation.

In step S3, when the detection results of both thermistors 5 and 6 are "x", the control unit 28 determines that the power feeding unit is out of order due to a disconnection of the electric cable 8. In this case, in step S10, the control unit 28 controls the AC power supply 29 to cut off (OFF) the AC current applied to the heat generating layer 13 of the film 1, turns off the fixing motor 30, and pressurizes the rollers. Stop the rotation of 3.

After that, the process proceeds to step S11, and the control unit 28 displays an error display indicating that the fixing device 108 is out of order on a display panel provided in an operation unit (not shown) of the image forming device 110 to notify the user. After that, the process proceeds to step S7 to end the operation. That is, the control unit 28 that also serves as the determination means determines the state of the fixing device 108 of the image forming apparatus 110 based on the detection results of both thermistors 5 and 6 (first and second temperature detecting means).

In the fixing device 108 of the present embodiment, the detection results of the thermistor 5 for detecting the temperature of the outer peripheral surface 1a of the film 1 and the thermistor 6 for detecting the temperature of the inner peripheral surface 1b of the film 1 are monitored. As a result, when the recording material P is wound around the outer peripheral surface 1a of the film 1, and the failure of the feeding portion of the fixing device 108 such as the disconnection of the electric cable 8 connecting between the AC power supply 29 and the heat generating layer 13 of the film 1 occurs. It can be carved out and judged.

Failure of the fixing device 108 such as disconnection of the electric cable 8 cannot be recovered by the user, but when the recording material P is wound around the outer peripheral surface 1a of the film 1, the user can recover it by himself / herself. In the present embodiment, it is possible to discriminate between the case where the recording material P is wound around the outer peripheral surface 1a of the film 1 and the failure of the fixing device 108 such as a disconnection of the electric cable 8. The recording material P wrapped around the outer peripheral surface 1a of the film 1 can also be removed by the user. Therefore, it is possible to reduce the chance that the fixing device 108 becomes unusable due to a failure in the fixing device 108.

As shown in FIG. 5, a normal time excluding an abnormal time such as when the recording material P is wound around the outer peripheral surface 1a of the film 1 is considered. Further, the time when the recording material P is wound around the outer peripheral surface 1a of the film 1 is taken into consideration. There is a difference in the detection result between the thermistor 5 that detects the temperature of the outer peripheral surface 1a of the film 1 and the thermistor 6 that detects the temperature of the inner peripheral surface 1b of the film 1 between the normal time and the winding time. The control unit 28 monitors the difference between the detection results of both thermistors 5 and 6. As a result, it is possible to detect the case where the recording material P is wound around the outer peripheral surface 1a of the film 1.

Further, the control unit 28 monitors the temperature difference between the detection results of both thermistors 5 and 6. This makes it possible to determine whether or not an alternating current is applied to the heat generating layer 13 of the film 1 of the fixing device 108. Alternatively, it can be determined whether or not a foreign substance such as the recording material P is retained between the outer peripheral surface 1a of the film 1 and the thermistor 5. It is possible to separate and determine these.

[Second Embodiment]
Next, the configuration of the second embodiment of the image forming apparatus according to the present invention will be described with reference to FIGS. 7 to 12. It should be noted that the same components as those in the first embodiment are given the same reference numerals or the same member names even if the reference numerals are different, and the description thereof will be omitted. FIG. 7 is a perspective explanatory view showing the configuration of the fixing device 108 of the present embodiment. FIG. 8 is a cross-sectional explanatory view showing the configuration of the fixing device 108 of the present embodiment.

In the first embodiment, the temperature of the outer peripheral surface 1a of the film 1 is detected by the thermistor 5 that abuts and slides on the outer peripheral surface 1a of the film 1. In this embodiment, as shown in FIGS. 7 and 8, a thermopile 17 that detects the temperature of the outer peripheral surface 1a of the film 1 from a position away from the outer peripheral surface 1a of the film 1 instead of the thermistor 5. Was provided and configured. The thermopile 17 is a thermal infrared sensor that generates a thermoelectromotive force according to the amount of incident energy when it receives infrared rays radiated from an object. The thermopile 17 is formed by connecting a plurality of thermocouples in series or in parallel.

In the fixing device 108 of the present embodiment, a thermopile 17 which is a non-contact temperature detecting element is provided facing the outer peripheral surface 1a of the film 1 as a first temperature detecting means for detecting the temperature of the outer peripheral surface 1a of the film 1. Be done. Further, as a second temperature detecting means for detecting the temperature of the inner peripheral surface 1b of the film 1, a thermistor 6 which is a contact type temperature detecting element is slidably provided on the inner peripheral surface 1b of the film 1.

Also in this embodiment, the thermopile 17 (first temperature detecting means) detects the temperature of the film 1 (heat generator) from one side. The thermistor 6 (second temperature detecting means) detects the temperature of the film 1 (heat generator) from the other surface. The thermopile 17 (first temperature detecting means) is provided on the outer peripheral surface 1a side of the film 1 (cylindrical film). The thermistor 6 (second temperature detecting means) is provided on the inner peripheral surface 1b side of the film 1 (cylindrical film).

The thermopile 17 is arranged outside the outer peripheral surface 1a of the film 1 by a predetermined distance, and detects the temperature of the outer peripheral surface 1a of the film 1. Regardless of the size of the recording material P used in the image forming apparatus 110, the case where the recording material P is wound around the outer peripheral surface 1a of the film 1 is detected. Therefore, the thermopile 17 is arranged in the minimum width region Am where the recording material P having the minimum width size used for the image forming apparatus 110 passes through the fixing nip portion N2. As shown in FIG. 7, in the image forming apparatus 110 of the present embodiment, the recording material P is conveyed to the fixing nip portion N2 with reference to the center. Therefore, the thermopile 17 is arranged at the center position in the longitudinal direction (left-right direction in FIG. 7) of the film 1.

The thermistor 6 is arranged on the inner peripheral surface 1b side of the film 1 and detects the temperature of the inner peripheral surface 1b of the film 1. The thermistor 6 is arranged at a position facing the thermopile 17 with the film 1 interposed therebetween. The thermopile 17 (first temperature detecting means) and the thermistor 6 (second temperature detecting means) face each other with the film 1 (heat generating element) interposed therebetween.

In this embodiment, the thermopile 17 and the thermistor 6 are arranged at the same position on the film 1. This makes it possible to detect with high accuracy. However, it is not always necessary to arrange the thermopile 17 and the thermistor 6 at the same position on the film 1.

The recording material P removes heat from the film 1. Therefore, the temperature of the passing region Ap of the recording material P on the outer peripheral surface 1a of the film 1 may be lower than that of the non-passing region An of the recording material P. Therefore, it is preferable that the thermistor 6 is also arranged in the minimum width region Am through which the recording material P having the minimum width size of the outer peripheral surface 1a of the film 1 passes, similarly to the thermopile 17. The thermopile 17 (first temperature detecting means) detects the temperature of the surface of the film 1 (heat generating element) facing the recording material P, and the thermopile 17 (first temperature detecting means) is attached to the image forming apparatus 110. It is provided within the range through which the recording material P having the minimum width to be used passes.

Further, in the present embodiment, as shown in FIG. 8, the direction of rotation of the film 1 with respect to the fixing nip portion N2 formed by the outer peripheral surface 1a of the film 1 and the pressure roller 3 with the thermopile 17 and the thermistor 6 (FIG. 8). It is installed on the downstream side (clockwise direction of 8). However, the arrangement positions of the thermopile 17 and the thermistor 6 need not be limited to this.

The fixing device 108 of the present embodiment has a high temperature rise rate and a short start-up time. Further, consider the case where power is supplied from the AC power supply 29 to the heat generating layer 13 of the film 1 in a state where the rotation of the film 1 is stopped because the film 1 itself generates heat. Then, since heat is not taken by the pressure roller 3 in the portion other than the fixing nip portion N2 of the film 1 in contact with the pressure roller 3, the temperature rise rate becomes higher than that when the film 1 is rotated.

The responsiveness of the contact-type thermistors 5 and 6 may not be sufficient for such a high rate of temperature rise. Therefore, in the temperature control using the contact type thermistors 5 and 6, power is supplied from the AC power supply 29 to the heat generating layer 13 of the film 1 in a state where the rotation of the film 1 is stopped due to some device abnormality such as slip of the film 1. Thermal damage to the film 1 may occur.

On the other hand, the responsiveness of the thermopile 17 is sufficiently high, and it is possible to sufficiently cope with the high rate of temperature rise of the film 1. Therefore, even when power is supplied from the AC power supply 29 to the heat generating layer 13 of the film 1 while the rotation of the film 1 is stopped, the temperature of the film 1 is safely controlled before the thermal damage to the film 1 occurs. Can be done. That is, in the fixing device 108 of the present embodiment, in addition to the operation and effect of the first embodiment, it is possible to suppress the excessive temperature rise of the film 1 even when some device abnormality such as slip of the film 1 occurs.

Next, a control method of the fixing device 108 of the present embodiment will be described with reference to FIG. 9. FIG. 9 is a flowchart showing a control method of the fixing device 108 of the present embodiment. The control common to the first embodiment will not be duplicated.

Steps S21 to S23 shown in FIG. 9 are the same as steps S1 to S3 shown in FIG. 6 except that the thermistor 5 is replaced with the thermopile 17, and therefore overlapping description will be omitted. In step S23, both the thermopile 17 provided in a non-contact manner facing the outer peripheral surface 1a of the film 1 and the thermistor 6 provided slidably with respect to the inner peripheral surface 1b of the film 1 are the film 1. Detects a temperature rise (“○”). In that case, the process proceeds to step S24, and the control unit 28 changes the control based on the detection result of the thermopile 17.

Consider the case where the thermopile 17 detects an abnormal temperature (temperature exceeding 250 ° C.) that cannot be reached during normal printing in step S24. In that case, the control unit 28 determines that power is being supplied from the AC power supply 29 to the heat generating layer 13 of the film 1 in a state where the rotation of the film 1 is stopped due to slipping or the like of the film 1.

In the present embodiment, when the temperature detected by the thermopile 17 exceeds 250 ° C., the control unit 28 is set to determine that the abnormal temperature has been reached. When the temperature detected by the thermopile 17 exceeds 250 ° C., the process proceeds to step S25, and the control unit 28 controls the AC power supply 29 to cut off the AC current applied to the heat generating layer 13 of the film 1 (OFF). Then, the fixing motor 30 is turned off to stop the rotation of the pressurizing roller 3.

After that, the control unit 28 proceeds to step S26 to display on a display panel provided in an operation unit (not shown) of the image forming apparatus 110 that the fixing device 108 is out of order and display an error to notify the user. After that, the process proceeds to step S27 to end the operation.

If the temperature detected by the thermopile 17 is 250 ° C. or lower in step S24, the process proceeds to step S28, and the control unit 28 controls the AC power supply 29 to apply an AC current to the heat generating layer 13 of the film 1. Then, printing is performed by performing normal temperature control.

After that, in step S29, the control unit 28 determines whether or not the accepted print job is completed, and if the accepted print job is completed, proceeds to step S30. While the received print job is not completed, the process returns to step S24. In step S30, the control unit 28 turns off the alternating current applied from the alternating current power supply 29 to the heat generating layer 13 of the film 1, turns off the rotational drive of the fixing motor 30, and stops the rotation of the pressurizing roller 3. After that, the process proceeds to step S27 to end the operation.

Steps S31 to S34 shown in FIG. 9 are the same as steps S8 to S11 shown in FIG. 6 except that the thermistor 5 is replaced with the thermopile 17, and therefore overlapping description will be omitted. That is, the control unit 28, which also serves as the determination means, determines the state of the fixing device 108 of the image forming apparatus 110 based on the detection results of the thermopile 17 and the thermistor 6 (first and second temperature detecting means). This makes it possible to prevent the film 1 from being overheated even when the film 1 is slipped.

In the image forming apparatus 110 of the present embodiment, the control unit 28 (determining means) is the difference between the detection result of the thermopile 17 (first temperature detecting means) and the detection result of the thermistor 6 (second temperature detecting means). Consider. Then, when the difference exceeds a predetermined threshold value, it is determined that some abnormality has occurred in the fixing device 108 of the image forming apparatus 110.

Specifically, in step S23, when 1.0 second has elapsed from the time when the heating layer 13 of the film 1 was started to be energized from the AC power supply 29, the control unit 28 has the detection temperature D17 of the thermopile 17 and the thermistor. Compare with the detection temperature D6 of 6. Then, the detection temperature D17 of the thermopile 17 provided in a non-contact manner facing the outer peripheral surface 1a of the film 1 is taken into consideration. Further, the detection temperature D6 of the thermistor 6 slidably provided with respect to the inner peripheral surface 1b of the film 1 is taken into consideration. When the detection temperature D17 of the thermopile 17 is 20 ° C. or more lower than the detection temperature D6 of the thermistor 6, the control unit 28 determines that the recording material P is wound around the outer peripheral surface 1a of the film 1.

Next, the behavior of the detected temperatures of the thermopile 17 and the thermistor 6 in the fixing device 108 of the present embodiment will be described with reference to FIGS. 10 to 12. FIG. 10 is a diagram showing temperature changes of the temperature detecting means in contact with the outer peripheral surface 1a and the inner peripheral surface 1b of the film 1 when the fixing temperature of the fixing device 108 of the present embodiment is raised. FIG. 11 is a diagram showing a temperature change of the temperature detecting means in contact with the outer peripheral surface 1a and the inner peripheral surface 1b of the film when the recording material P of the fixing device 108 of the present embodiment is wound. FIG. 12 shows the temperature detecting means in contact with the outer peripheral surface 1a and the inner peripheral surface 1b of the film 1 when the heat generating layer 13 is energized when the rotation of the film 1 of the fixing device 108 of the present embodiment is stopped. It is a figure which shows the temperature change.

FIG. 10 shows changes in the detection temperatures D17 and D6 of the thermopile 17 and the thermistor 6 when the fixing device 108 is started up. As shown in FIG. 10, the temperature of the film 1 rises with the lapse of the energization time from the AC power supply 29 to the heat generating layer 13 of the film 1, and the thermopile 17 and the thermistor 6 detect the temperature rise of the film 1. I understand.

In FIG. 10, the detection temperature D17 of the thermopile 17 was 113 ° C. when 1.0 second had elapsed from the time (0.0 seconds) when the heating layer 13 of the film 1 was started to be energized from the AC power supply 29. On the other hand, the detection temperature D6 of the thermistor 6 was 100 ° C. The detection temperature difference ΔD between the detection temperature D17 of the thermopile 17 and the detection temperature D6 of the thermistor 6 is 13 ° C. (= 113 ° C.-100 ° C.). Since the detected temperature difference ΔD at 13 ° C. is smaller than the threshold value of 20 ° C. for determining an abnormality, the control unit 28 determines that there is no abnormality.

Then, the normal printing operation is performed by proceeding to steps S23, S24, S28, and S29 shown in FIG. Further, as shown in FIG. 10, it can be seen that there is a detection temperature difference ΔD between the detection temperatures of the thermopile 17 and the thermistor 6. The thermopile 17 is more responsive than the thermistor 6. Therefore, the temperature of the thermopile 17 changes faster than that of the thermistor 6 with respect to the temperature change of the film 1.

FIG. 11 shows changes in the detection temperatures D17 and D6 of the thermopile 17 and the thermistor 6 when the recording material P is wound around the outer peripheral surface 1a of the film 1 and the heating layer 13 of the film 1 is energized from the AC power supply 29. show. In FIG. 11, the detection temperature D17 of the thermopile 17 was 26 ° C. when 1.0 second had elapsed from the time (0.0 seconds) when the heating layer 13 of the film 1 was started to be energized from the AC power supply 29. On the other hand, the detection temperature D6 of the thermistor 6 was 80 ° C. The detection temperature difference ΔD between the detection temperature D17 of the thermopile 17 and the detection temperature D6 of the thermistor 6 is 54 ° C. (= 80 ° C. −26 ° C.).

At this time, since the recording material P is interposed between the thermopile 17 and the outer peripheral surface 1a of the film 1, the thermopile 17 cannot detect the accurate temperature of the outer peripheral surface 1a of the film 1. Therefore, as shown in FIG. 11, the detection temperature D17 of the thermopile 17 does not change much. On the other hand, the thermistor 6 keeps in contact with the inner peripheral surface 1b of the film 1. Therefore, even if the recording material P is wound around the outer peripheral surface 1a of the film 1, the detection temperature D6 of the thermistor 6 does not decrease significantly, and the temperature rise of the inner peripheral surface 1b of the film 1 is correctly detected. In the case shown in FIG. 11, the detected temperature difference ΔD at 54 ° C. is larger than the threshold value of 20 ° C. for determining an abnormality.

Therefore, the control unit 28 determines that the recording material P is wound around the outer peripheral surface 1a of the film 1. Then, the process proceeds to steps S23, S31, S32, and S27 shown in FIG. 9 to stop the energization from the AC power supply 29 to the heat generating layer 13 of the film 1. Further, the rotation drive of the fixing motor 30 is turned off to stop the rotation of the pressurizing roller 3. The control unit 28 (determining means) combines the thermopile 17 (first temperature detecting means) and the film 1 (heating element) based on the detection results of the thermopile 17 and the thermistor 6 (first and second temperature detecting means). It can be determined that foreign matter such as the recording material P is accumulated between them.

FIG. 12 shows changes in the detection temperatures D17 and D6 of the thermopile 17 and the thermistor 6 when the heat generating layer 13 of the film 1 is energized from the AC power supply 29 in a state where the rotation of the film 1 is stopped. In FIG. 12, the detection temperature D17 of the thermopile 17 was 199 ° C. when 1.0 second had elapsed from the time (0.0 seconds) when the heating layer 13 of the film 1 was started to be energized from the AC power supply 29. On the other hand, the detection temperature D6 of the thermistor 6 was 86 ° C. The detection temperature difference ΔD between the detection temperature D17 of the thermopile 17 and the detection temperature D6 of the thermistor 6 is 113 ° C. (= 199 ° C. −86 ° C.).

Both the thermopile 17 and the thermistor 6 detect a temperature rise of the film 1. In FIG. 12, the thermistor 6 has a slow response, and the detection temperature is delayed. Then, the detection temperature D17 of the thermopile 17 reaches 250 ° C. when about 1.3 seconds have elapsed from the time (0.0 seconds) when the heating layer 13 of the film 1 is started to be energized from the AC power supply 29.

At this time, the control unit 28 determines that the recording material P has reached an abnormal temperature (temperature exceeding 250 ° C.) that does not reach in normal times except when the recording material P is wound around the outer peripheral surface 1a of the film 1. In this case, the control unit 28 determines that the heat generating layer 13 of the film 1 is energized from the AC power supply 29 when the film 1 slips. Then, the process proceeds to steps S23, S33, S34, and S27 shown in FIG. 9 to stop the energization from the AC power supply 29 to the heat generating layer 13 of the film 1. Further, the rotation drive of the fixing motor 30 is turned off to stop the rotation of the pressurizing roller 3.

As in the present embodiment, the control unit 28 has the thermopile 17 and the thermistor 6 at a time when 1.0 second has elapsed from the time (0.0 seconds) when the heating layer 13 of the film 1 is energized from the AC power supply 29. Monitor each detection temperature of. Then, as shown in FIG. 11, when the detection temperature D6 of the thermistor 6 is higher than the detection temperature D17 of the thermopile 17 by 20 ° C. or more, the control unit 28 has the recording material P on the outer peripheral surface 1a of the film 1. Judge that it is wrapped. Then, the energization from the AC power supply 29 to the heat generating layer 13 of the film 1 is stopped. Further, the rotation drive of the fixing motor 30 is turned off to stop the rotation of the pressurizing roller 3.

Further, the control unit 28 constantly monitors the detection temperature D17 of the thermopile 17 when the AC power supply 29 is energized to the heat generating layer 13 of the film 1. Then, as shown in FIG. 12, when the detection temperature D17 of the thermopile 17 becomes 250 ° C. or higher, the control unit 28 is energized from the AC power supply 29 to the heat generating layer 13 of the film 1 when the film 1 slips. It is determined that there is. Then, the energization from the AC power supply 29 to the heat generating layer 13 of the film 1 is stopped, the rotation drive of the fixing motor 30 is turned off, and the rotation of the pressurizing roller 3 is stopped.

In the fixing device 108 of the present embodiment, the control unit 28 winds the recording material P around the outer peripheral surface 1a of the film 1, and the electric cable 8 connecting the AC power supply 29 and the heat generating layer 13 of the film 1 is disconnected. It can be determined that the fixing device 108 is out of order. The recording material P wrapped around the outer peripheral surface 1a of the film 1 can also be removed by the user. As a result, it is possible to reduce the chance that the fixing device 108 becomes unusable due to the occurrence of a failure of the fixing device 108.

It is possible to suppress thermal damage to the film 1 due to energization of the heat generating layer 13 of the film 1 from the AC power supply 29 when the film 1 slips. As a result, the chance of failure of the fixing device 108 can be further reduced. Each set value such as temperature and time used by the control unit 28 for abnormality determination can be appropriately set by designing the fixing device 108.

In the present embodiment, an example in which the thermopile 17 is used as the first temperature detecting means for detecting the temperature of the outer peripheral surface 1a of the film 1 has been described, but other fast-responsive bolometers and pyrosensors (pyroelectric type) have been described. An element such as an infrared sensor) may be used. Bolometers measure temperature through the heat received by substances with electrical resistance that depend on temperature for radiant energy such as electromagnetic waves. The other configurations are the same as those in the first embodiment, and the same effects can be obtained.

P ... Recording material 1 ... Film (heating element; tubular film)
5 ... Thermistor (first temperature detecting means)
6 ... Thermistor (second temperature detecting means)
28 ... Control unit (determination means)
102 ... Process cartridge (image forming means)
110 ... Image forming apparatus

Claims (3)

An image forming apparatus having an image forming means for forming an image on a recording material.
A tubular film containing a heating element and
A first temperature detecting means, which is arranged non-contactly on the outer peripheral surface side of the film at a position facing the film and detects the temperature of the heating element from the outer peripheral surface side .
A second temperature detecting means, which is arranged in contact with the position facing the film on the inner peripheral surface side of the film and detects the temperature of the heating element from the inner peripheral surface side .
A determination means for determining the state of the image forming apparatus based on the detection results of the first and second temperature detecting means, and a determination means.
Have,
The first temperature detecting means is more responsive than the second temperature detecting means.
When power is supplied to the heating element, the temperature detected by the first temperature detecting means rises, and the temperature detected by the second temperature detecting means rises in the first state. If the temperature detected by the first temperature detecting means does not reach the threshold temperature , which is an abnormal temperature that cannot be reached at the time of printing, the determination means determines that the normal state is reached, and the determination means has reached the threshold temperature . For example, it is determined that the film is in the first abnormal state of slipping, and the temperature is determined to be the first abnormal state.
When power is supplied to the heating element, the temperature detected by the second temperature detecting means is higher than the temperature detected by the first temperature detecting means, and the temperature is higher than that detected by the first temperature detecting means. When the difference between the temperature detected by the temperature detecting means and the temperature detected by the second temperature detecting means becomes a second state larger than a predetermined value, the recording material is wound around the film in the determining means. Judging that it is the second abnormal state ,
When power is supplied to the heating element, the temperature detected by the first temperature detecting means does not rise, and the temperature detected by the second temperature detecting means does not rise in the third state. The image forming apparatus is characterized in that the determination means determines that it is in a third abnormal state, which is a failure of the feeding unit . The image forming apparatus according to claim 1, wherein the first temperature detecting means and the second temperature detecting means face each other with the heating element interposed therebetween. The first temperature detecting means detects the temperature of the surface of the heating element facing the recording material, and the first temperature detecting means passes the recording material having the minimum width used for the image forming apparatus. The image forming apparatus according to claim 1 or 2 , wherein the image forming apparatus is provided within the range of the above.

Images