JP2006098692A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device equipped with a function of easily detecting whether a web unit detachably fitted to a device main body with a rotary body for fixation is mounted and whether a cleaning web is present in an inexpensive and simple way. <P>SOLUTION: The fixing device is provided with a detection device which includes a detection circuit constituted by connecting a 1st circuit having switches 41 and 42 operating according to the presence of an unused cleaning web 21 of a web unit 20 to a 2nd circuit having a switch 52 operating according to the attachment/detachment state of the web unit 20 in parallel, and detects whether the whole circuit is in a conductive state or non-conductive state when the detection circuit is supplied with electric power to determine whether the web is present and whether the web unit is mounted. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixing device used for fixing a toner image formed on an image forming apparatus such as a printer, a copying machine, or a multi-function machine using an electrophotographic method, an electrostatic recording method, or the like to a recording medium, In particular, a long cleaning web for cleaning a fixing rotating body for fixing is configured as a web unit that is detachably attached to the apparatus main body. The present invention relates to a fixing device having a function of detecting presence or absence.

  As this type of fixing device, for example, a recording medium on which a toner image is transferred to a fixing rotating body (fixing nip) composed of a pressure roll and a pressure roll rotating while being pressed to form a fixing nip In many cases, an unfixed toner image is fixed to a recording medium by heating and pressurizing it so as to be in contact with each other.

  In such a fixing device, good fixing may be hindered by foreign matters such as toner and paper dust adhering to the surface of the fixing rotating body.

  For this reason, in order to remove the foreign matter and clean it, it is cleaned by feeding a predetermined amount from a state in which a long (long sheet) cleaning web is wound around the feeding shaft and contacting the fixing rotating body, There is also a fixing device that applies a web-type cleaning device that winds a cleaning web after cleaning around a winding shaft.

  Further, regarding the web-type cleaning device, it is necessary to replenish the web or replace the device itself when the unused cleaning web fed from the feeding shaft becomes a small amount or completely disappears. Therefore, it is often unitized so that it can be detachably attached to the main body of the fixing device.

  In a fixing device equipped with such a web-type cleaning device, it is necessary to detect the presence or absence (including the remaining amount) of the cleaning web and inform the user of the replacement time. For example, the following is known as a fixing device having means capable of detecting the amount.

  That is, as a web remaining amount detecting means for detecting that the remaining amount of the unused web wound around the web feeding shaft reaches a predetermined amount, the web is pressed against the web wound around the feeding shaft. When the conductive spring member urged in the axial direction of the shaft is reduced to a predetermined remaining amount, the conductive spring member is brought into contact with the feed shaft connected to the shaft electrode, and this state is detected by the conduction detecting means. In this case, the fixing device includes a configuration in which the determination unit determines that the remaining amount of the unused web has reached a predetermined amount (Patent Document 1).

  However, in the conventional fixing device employing this web remaining amount detecting means, the remaining amount of web in the web unit in use is detected, but it is not detected whether or not the web unit is mounted on the fixing device body. . For example, when a fixing operation (image forming operation) is performed without the web unit being accidentally mounted, the fixing device main body is opened at the mounting portion of the web unit. The heat for heat fixing is released, and as a result, it becomes difficult to stably maintain the heating temperature for fixing, or the temperature in the image forming apparatus rises abnormally. Inconvenience occurs. For this reason, in this fixing device, in addition to the web remaining amount detecting means, it is necessary to separately provide means for detecting the presence / absence of the web unit. Depending on the configuration of the means for detecting the presence / absence of the web unit, etc. There is a risk that the apparatus becomes complicated and the cost is greatly increased.

  In addition, as a fixing device including a web-type cleaning device, a component in the case where a mechanism for detecting the presence or absence of the cleaning web and a mechanism for detecting the presence or absence of the web unit are provided separately. In order to eliminate the complexity of the apparatus and the accompanying complexity, a fixing apparatus having a detection mechanism as described below is known.

  This uses a web detecting means having an actuator supported so as to be in contact with the back surface of the cleaning web and a sensor for detecting the state of the actuator, and also serving as a cleaning web in the winding end region. In this fixing device, a fixing device having a detection opening at a position corresponding to the contact position is used (Patent Document 2).

  In fact, in this fixing device, when the web unit is mounted, the actuator of the web detecting means comes into contact with the back surface of the cleaning web and moves to the detection position side to be detected by the sensor (the sensor is turned on). Thereby, it is detected that the unit is mounted.

  Further, when the web is not on the actuator due to the passage of the cleaning web through the opening for detection, the actuator moves to the non-detection position side and is not detected by the sensor (the sensor is turned off). Re-detection by the actuator is performed in a state where the winding shaft rotates at a speed higher than the normal speed. If there is a web on the actuator at the time of this re-detection, the actuator moves and is detected by the sensor, thereby detecting that the web is the end portion and reporting the time for replacing the web. On the other hand, when there is no web on the actuator at the time of this re-detection, the actuator does not move and is not detected by the sensor, thereby detecting that the web unit is not mounted and reporting to that effect.

JP 2000-66546 A (Claims, FIGS. 2 to 6, etc.) Japanese Patent Laid-Open No. 10-307504 (paragraphs 0013 to 0016, FIGS. 1 and 2, etc.)

  However, even the fixing device in which the detection function for presence / absence of the web unit and the detection function for the presence / absence of the cleaning web are performed by the same detection mechanism has the following problems.

  First, as the cleaning web, a dedicated web having an opening for detection must be used, which is inferior in versatility and increases the cost. In addition, in order to detect the end of the web and to detect whether the web unit is not mounted, a separate drive system control operation is required to increase the rotational speed of the winding shaft from the normal time, and the detection method is complicated. Therefore, there is a risk of increasing the cost accordingly.

  The present invention has been made in view of the above-described problems and the like. The detection of the presence / absence of the web unit and the detection of the presence / absence of the cleaning web are performed using a special cleaning web, a drive system, or the like. There is provided a fixing device having a function that can be easily performed by an inexpensive and simple method without the need for performing another control operation.

  The fixing device according to the present invention includes an apparatus main body provided with a fixing rotator for fixing an unfixed toner image on a recording medium, and a long shape that is detachably attached to the apparatus main body and cleans the fixing rotator. A web unit having a configuration in which the cleaning web is wound from the state wound around the feed shaft and brought into contact with the portion to be cleaned of the fixing rotator and then wound around the take-up shaft, and an unused cleaning web in the web unit A first circuit provided with a switch that operates according to the presence state of the web unit and a second circuit provided with a switch that operates according to the attachment / detachment state of the web unit are connected in parallel to form one detection circuit; and When power is supplied to the detection circuit, it is detected whether the entire circuit is in a conductive state or a non-conductive state, and the presence or absence of the cleaning web and the installation of the web unit It is characterized in that it has a detection device for determining the free.

  For the detection device, for example, when there is a cleaning web, the switch of the first circuit cuts the circuit, and when the web unit is mounted, the switch of the second circuit cuts the circuit. It is good to set it so that it becomes.

  For the detection device configured in this way, it is further determined that there is no usable cleaning web in the web unit when the entire detection circuit changes from a non-conductive state to a conductive state during power supply. It may be set to stop the supply of power to the detection circuit.

  Further, in the fixing device as described above, for example, as a switch of the first circuit, the circuit is disconnected by an unused cleaning web being interposed, while the circuit is disconnected by the absence of the web. When the web unit is attached to the main body of the device as a switch of the second circuit, the circuit is cut off in conjunction with the second circuit switch. It may be configured to use a mechanism that interlocks the circuit when it is removed from the circuit. In this case, it is possible to easily configure the detection device, and it is possible to easily detect the presence or absence of an unused cleaning web or the presence of a web unit that is the detection target.

  According to such a fixing device of the present invention, whether one detection circuit formed by connecting the first circuit and the second circuit in the detection device in parallel is in an energized state or a non-energized state when power is supplied. By detecting, it is possible to detect the presence or absence of the web unit and the presence or absence of the cleaning web.

  In this fixing device, the detection device for performing the two detections is simply connected in parallel with two circuits each having a switch that operates according to each state of the article to be detected (web unit and its cleaning web). Since it consists of a simple detection circuit, and the two detections are made only by detecting the conduction or non-conduction state of the detection circuit, the two detections can be easily performed by a low-cost and simple method. be able to. Further, in the detection, it is not necessary to use a special cleaning web or perform other control operations such as a drive system, and in this respect, it is possible to perform simple and inexpensive detection.

  Further, the detection device in the fixing device is set so that the switch of the first circuit is cut off when the cleaning web is present and the switch of the second circuit is cut off when the web unit is attached. In this case, if the detection circuit including the first circuit and the second circuit is in a non-energized state when power is supplied, it can be seen that the web unit is mounted and the cleaning web is also present. On the contrary, if the detection circuit is energized when power is supplied, it can be seen that the web unit is not mounted or the cleaning web is not present.

  Further, in the above detection device, when the entire detection circuit is changed from a non-conductive state to a conductive state during power supply, it is determined to determine that there is no usable cleaning web in the web unit. The absence of a usable cleaning web can be detected very simply and reliably. When the fixing unit is such that the web unit can be freely removed when the fixing operation is possible, the web unit is removed when the detection circuit changes from a non-energized state to a conductive state. In other words, it is impossible to determine that there is no usable cleaning web. However, this detachable web unit is normally regulated so that it can be removed for the first time in a state where the fixing operation is prohibited (the power supply to the detection circuit is also stopped accordingly), and the fixing operation is possible. Then, it has a structure that cannot be removed.

  FIG. 1 is a cross-sectional view showing a main part of a fixing device according to Embodiment 1 to which the present invention is applied.

  The fixing device 1 is roughly composed of an apparatus main body 10 equipped with a fixing roll 11 and a pressure roll 13 and a web unit 20 that is detachably attached to the apparatus main body 10.

  The apparatus main body 10 has a box shape as a whole. As shown in FIGS. 1 and 2, the upper surface portion 10 a is opened and a recording sheet P to be fixed is introduced into the fixing apparatus 1. A portion 10b and a portion 10c from which the recording paper P after fixing is discharged are opened. The fixing roll 11 is a cylindrical roll installed inside the apparatus main body 10 so as to be rotationally driven in a predetermined direction, and is fixedly installed in the inner space of the roll to heat the roll to a predetermined temperature. And an electric heater. Further, the pressure roll 13 is a cylindrical roll that is rotatably installed inside the apparatus main body 10 so as to form a fixing nip portion FN in pressure contact with the fixing roller 12. A predetermined pressure is applied by the mechanism and pressed against the fixing roll 11.

  In such a fixing device 1, when the fixing operation is started, the recording paper P on which the toner image T is formed and transferred on the image forming device (not shown) is conveyed toward the fixing device 1, and the introduction opening of the device main body is transferred. After being introduced from 10b, it is passed through the fixing nip FN between the fixing roll 11 and the pressure roll 13 which are rotated and heated. As a result, the paper P carrying the unfixed toner image T is heated and pressurized in the fixing nip portion FN, so that the toner image T is melted and fixed to the paper P. A one-dot chain line with an arrow in FIG.

  The web unit 20 includes a cleaning web 21 for removing foreign matters such as toner adhering to the surface of the fixing roll 11 as shown in FIGS. In addition, the cleaning web 21 is wound around a predetermined amount in advance and sent out from the wound state, the cleaning web 23 sent out is brought into contact with the fixing roll 11, and the pressing roll 24 is pressed. A winding shaft 25 for winding the cleaning web 21 after contacting and cleaning is attached to each other so as to be rotatable.

  The cleaning web 21 is a long electrically insulating sheet having a width corresponding to the width of the fixing region of the fixing roll 11 and is formed of a nonwoven fabric or the like. The delivery shaft 23 has a configuration in which at least the roll surface has conductivity. Furthermore, the pressing roll 24 is formed of an elastic roll having an elastic layer formed thereon. 3, reference numerals 22a and 22b are brackets provided with bearings for rotatably supporting the shafts 23 and 25 and the roll 24, and 22c is a fixing screw for fixing the unit frame 22 to the apparatus main body 10. It is a through hole. Reference numeral 27 in the figure denotes a drive transmission gear train for transmitting power for rotating the shafts 23 and 25 and the roll 24 in a predetermined direction at a predetermined speed. A part of gears of the gear train 27 is structured to be engaged with and connected to a transmission gear of a drive system (not shown) on the apparatus main body 10 side when the web unit 20 is attached.

  When such a web unit 20 is mounted on the apparatus main body 10 in a state where the cleaning web 21 supported on the back side by the pressing roll 24 is in contact with the fixing roll 11, the fixing operation time comes, as shown in FIG. Then, the cleaning web 21 is fed out by a predetermined amount from the rotating feed shaft 23 and is pressed against the surface of the fixing roll 11 with a predetermined pressure by the pressing roll 24. Accordingly, the cleaning web 21 is recovered so as to come into contact with the surface of the rotating fixing roll 11 and capture the foreign matter adhering to the surface, and the fixing roll 11 is cleaned. The cleaning web 21 after the cleaning is completed is wound around a winding shaft 25 that is driven to rotate.

  The web unit 20 is either removed from the apparatus main body 10 and replaced with a new web unit 20 when the unused cleaning web 21 wound around the delivery shaft 23 is used up, or a new cleaning web 21 is wound around the web unit 20. Only the delivery shaft 23 and the like are exchanged. Further, the attaching and detaching operations of the web unit 20 are performed after the open / close door at a position accessible to the fixing device 1 is opened in the image forming apparatus in which the fixing device 1 is used. .

  In the fixing device 1, a detection device 30 is provided for detecting whether or not the web unit 20 is attached to the apparatus body 10 and whether or not the unused cleaning web 21 is present in the attached web unit 20. Yes.

  As shown in FIGS. 3 to 6 and the like, the detection device 30 is installed on the web unit 20 side to detect the presence or absence of an unused cleaning web 21 and the web unit is installed on the device body 10 side. When the power is supplied to the second circuit 32 that detects the presence or absence of the 20 and the detection circuit 33 in which the first circuit 31 and the second circuit 32 are connected in parallel, the entire circuit is in a conductive state or a non-conductive state. It is comprised with the detection part 35 which detects which is.

  As shown in FIG. 3 and the like, the first circuit 31 has a free end abutting against the cleaning web 21 wound around the shaft at a position different from the conductive shaft 23 in the axial direction and the shaft 20. Two switches 41, 42 (first switch 41 and second switch 42) made of conductive leaf spring members fixedly attached to the unit frame 22 so as to be elastically biased toward the surface of The two contact terminals 43, 44 (first terminal 43, second terminal 44) provided at one end on the inner surface side of the unit frame 22, and the contact terminals 43, 44 and the two switches 41, 42 are individually provided. And wiring members 45 and 46 for wiring. In this embodiment, the contact terminal 43 and the first switch 41 are connected by a wiring material 45, and the contact terminal 44 and the second switch 42 are connected by a wiring material 46. In this way, as shown in FIGS. 6 and 7, the first circuit 31 has two switches in which the electric power supplied between the contact terminals 43 and 44 contacts and separates from the conductive delivery shaft 23 at different positions. The circuit is connected or disconnected by 41 and 42.

  As shown in FIG. 5 and the like, the two switches 41 and 42 are electrically conductive due to the interposition of the insulating web 21 when the unused cleaning web 21 remains on the delivery shaft 23. The first circuit 31 is shut off without contacting the shaft 23 (non-conducting state: states 41A and 42A shown by two-dot chain lines in FIG. 5). On the other hand, when the unused cleaning web 21 disappears from the delivery shaft 23, the leaf spring member is removed from the insulating web 21 and comes into contact with the conductive shaft 23, and the first circuit 31 is connected. (Conducting state: states 41B and 42B shown by solid lines in FIG. 5).

  As shown in FIG. 4 and the like, the second circuit 32 is a push button that is pushed from above to the circuit holder 51 attached to the upper part 10a on the one end side of the apparatus body 10 and pushed downward when the web unit 20 is attached. Type switch 52, two wiring terminals 53 and 54 connected to the power source 36 of the detection unit 35, and wiring made of a metal plate or the like for individually wiring the wiring terminals 53 and 54 and the push button type switch 52 The members 55 and 56 are electrically connected to the wiring terminals 53 and 54 (or the wiring members 55 and 56), and can contact the contact terminals 43 and 44 of the first circuit 31 at positions on both sides of the switch 52. It consists of two contact terminals 57 and 58. As described above, the second circuit 32 is a circuit in which the power supplied between the wiring terminals 53 and 54 is connected or disconnected by the push button type switch 52, as shown in FIGS. . In addition, the first circuit 31 and the second circuit 32 become one detection circuit 33 connected in parallel when the contact terminals 43 and 44 and the contact terminals 57 and 58 are in contact with each other. For example, detection power is supplied from a power source 36 installed in the detection unit 35.

  When the web unit 20 is not mounted, the push button type switch 52 has a non-conductive button main body 52a supported by a conductive spring 59 installed on the lower side thereof and an upper portion thereof. The side protrudes from the upper end of the circuit holder 51. The spring 59 is connected in contact with a part 55a of the wiring member 55 at a lower portion thereof. In addition, at this time, the switch 52 is in a state in which the upper portion 59a of the spring 59 that is in contact with the lower protrusion 52b of the button main body 52a is in contact with the portion 56a of the wiring member 56. The circuit 32 is made conductive. On the other hand, when the web unit 20 is mounted, the button main body 52 a is pushed downward by the unit frame 22, and is pushed downward against the elastic repulsion force of the spring 59. In addition, at this time, the switch 52 is in a state in which the upper protrusion 59a of the spring 59 is separated from the part 56a of the wiring member 56 (non-contact state) by causing the lower protrusion 52b to press and contract the spring 59. Thus, the second circuit 32 is turned off.

  The detection unit 35 includes a power source (DC power source) 36 that supplies power (current) for detection to the detection circuit 33 including the first circuit 31 and the second circuit 32, and an output terminal of the power source 36 and the second circuit 32. Two conducting wires 37 and 38 that connect the wiring terminals 53 and 54, and a continuity detector that detects whether the detection circuit 33 is in a conducting state or a non-conducting state when power is supplied from the power source 36. 39. The detection unit 35 can be disposed at a position separated from the detection circuit 33 via wirings 37 and 38, and can be disposed on the image forming apparatus side using the fixing device 1, for example. The power supply from the power source 36 is started when the fixing device 1 or the image forming apparatus becomes operable (usable), and is stopped when the operation becomes impossible. The continuity detector 39 is connected, for example, by inserting a resistance element between the output side of the positive pole of the power supply 36 and the wiring 38, and taking out the voltage change at the time of power supply on the wiring 38 side as an output (signal). Composed. In addition, the continuity detector 39 may be configured using, for example, an ammeter or a photocoupler. The continuity detector 39 may be integrated with the power source 36 (control unit thereof).

  Further, the detection unit 35 performs an operation of determining the presence / absence of the cleaning web 21 and the presence / absence of the web unit 20 based on the operation of supplying power from the power source 36 and the detection result from the continuity detector 39. In this embodiment, as shown in FIG. 8, as will be described later, the fixing device 1 or the central control unit 60 of the image forming apparatus (by a microcomputer or the like) can be provided. Connected). As a result, the operation of the detection unit 35 is controlled by the central control unit 60, or the detection result (actually the detection result of the continuity detector 39) is transmitted to the central control unit 60 as described later. In the process, the presence or absence of the cleaning web 21 and the presence or absence of the web unit 20 are determined.

  The central control unit 60 connected to the detection unit 35 determines each part of the fixing device (driving system, heating system, etc.) and each part of the image forming apparatus (image forming unit and paper transport unit) according to the detection result (discrimination result). The operation of the drive system or the like is appropriately controlled (including continuation and stop of the operation, for example) through the corresponding control unit 61. Further, a required warning is given to the display unit 65 such as a liquid crystal panel or a lamp in accordance with the detection result (discrimination result).

  Hereinafter, the operation of the detection device 30 will be described with reference to FIGS.

  First, the detection device 30 is set in advance so that when the web unit 20 is not attached to the device main body 10, the push button switch 52 in the second circuit 32 is connected to the circuit 32 as described above. (FIGS. 6 and 10). Further, when there is an unused cleaning web 21 on the feeding shaft 23 of the web unit 20, the first switch 41 and the second switch 42 in the first circuit 31 are in a state where the circuit 31 is disconnected as described above. (FIG. 6, FIG. 10, etc.).

  First, when the fixing device 1 or the image forming apparatus becomes operable, power is supplied from the power source 36 of the detection unit 35 to the detection circuit 33 (step 10: S10). Here, the state in which the fixing device 1 or the image forming apparatus is operable means that, for example, the main power supply is turned on and the work opening / closing door (especially a door in which an interlock switch is installed) is ensured. It seems to be closed.

  When power is supplied to the detection circuit 33, it is determined whether or not the conduction detector 39 of the detection unit 35 is energized (S11).

  If it is determined that the state is “non-energized” at this time, the central control unit 60 determines that the web unit 20 is attached to the apparatus main body 10 and that the cleaning web 21 is also present in the unit 20 (S12). ).

  That is, as shown in FIGS. 6 and 11 to 12, if the web unit 20 is mounted on the apparatus main body 10, the unit frame 22 abuts on the button type switch 52 of the second circuit 32 and the switch 52 is moved. Since the circuit is pushed down, the circuit 32 is disconnected. At this time, if there is an unused cleaning web 21 on the feeding shaft 23 of the web unit 20 (if it remains), the web 21 is placed between the switches 41 and 42 of the first circuit 31 and the shaft 23. Since the switches 41 and 42 do not come into contact with the shaft 23 due to the interposition, the circuit 31 is disconnected. Accordingly, in this case, since both the first circuit 31 and the second circuit are disconnected, the entire detection circuit 33 is in a non-energized state (FIGS. 6, 11, and 12).

  In this case, the central control unit 60 regards the web unit 20 and the web 21 as being in a normal state, and continues the operation of the fixing device 1 (image forming apparatus) as it is (S113). Thus, the normal fixing operation by the fixing device 1 as described above is performed, and the fixing roll 11 is cleaned by the web unit 20. By the way, when this operation is executed, the cleaning web 21 in the web unit 20 is gradually fed out and consumed, so that the unused cleaning web 21 remaining on the feeding shaft 23 gradually decreases.

  On the other hand, if it is determined in step S <b> 11 that the power is on, the central control unit 60 determines that the web unit 20 is not attached to the apparatus body 10 or that the unit 20 does not have the cleaning web 21. (S15).

  That is, as shown in FIGS. 7 and 10, if the web unit 20 is not attached to the apparatus main body 10, the button type switch 52 of the second circuit 32 protrudes without being pushed down by the unit frame 22. Therefore, the circuit 32 is connected (the state of the switch 52 drawn by a two-dot chain line in FIG. 7). At this time, if there is no unused cleaning web 21 on the feeding shaft 23 of the web unit 20 (if it does not remain), the web 21 is interposed between the switches 41 and 42 of the first circuit 31 and the shaft 23. Therefore, both of the switches 41 and 42 come into contact with the shaft 23 and the circuit 31 is connected. Therefore, at this time, since the first circuit 31 and the second circuit are both connected, the entire detection circuit 33 is in a non-energized state (FIGS. 7 and 10).

  In this case, the central control unit 60 regards that the web unit 20 and the web 21 do not exist, and stops the operation of the fixing device 1 (image forming apparatus) (S16). As a result, the operation is continued without the web unit 20 being mounted, so that heat is released from the inside of the apparatus main body 10 without causing problems such as an abnormal increase in the internal temperature of the image forming apparatus or the like. In addition, it is possible to prevent the fixing roll 11 from being stained and the accompanying fixing failure due to the absence of the cleaning web 21. In addition, at this time, the power supply from the power source 36 to the detection circuit 33 is also stopped (S16).

  In this case, a warning message is displayed on the display unit 65 that prompts the user to check whether the web unit 20 is installed or the web 21 is present (S17). Thereby, when the web unit 20 is not mounted, the user can be notified of the mounting, and when the cleaning web 21 is not present, the replacement (replenishment) can be notified to the user.

  In particular, in the detection device 30, when the entire detection circuit 33 changes from a non-conductive state to a conductive state while power is supplied from the power source 36 in the detection unit 35, it is used in the web unit 20. It is determined that the possible cleaning web 21 is gone. This is because the first circuit 31 and the second circuit 32 in the detection circuit 33 are connected in parallel to the power source 36, and therefore the switches 41 and 42 of the first circuit 31 are connected to each other due to the absence of the cleaning web 21. This is because the detection circuit 33 is brought into a normal state by the first circuit 31 in the connected state. Further, in this case, a warning message such as “Replace web unit” or “Replace cleaning web” is displayed on the display unit 65 in step S17.

  When such a warning message is displayed, the web unit 20 is attached or exchanged or the web 21 is exchanged by a user, a service person, or the like. This operation is usually performed with the open / close door for the operation opened.

  When this operation is finished and the door is closed (in some cases, the power is turned on), the detection operation by the detection device 30 described above is performed in the same manner.

  As described above, according to the fixing device 1, the detection device 30 can easily detect the presence / absence of the web unit 20 and the presence / absence of the cleaning web 21. In addition, this detection does not require the use of a special cleaning web as in the prior art, and it is not necessary to perform other control operations such as a drive system, thereby increasing unnecessary costs and complication of the apparatus. Simple detection is possible without incurring.

  In the first embodiment, the case where the type (41, 42) using the conductive shaft 23 as a part of the circuit is used as the switch of the first circuit 31 in the detection device 30 is described. The switch of the 1st circuit 31 should just operate according to the state of the web 21 whether the unused cleaning web 21 exists. As such a switch, for example, an electrode is installed on one side of the cleaning web 21 between the feeding shaft 23 and the pressing roll 24, and the web 21 is in contact with the web 21 on the opposite side. For example, there is a switch of a type in which a circuit is connected in contact with the electrode when there is no more. Further, the number of switches of the first circuit 31 in the first embodiment may be one. In this case, the conductive delivery shaft 23 may be connected to the contact terminal 43 (44) which is not connected to the one switch.

  In the first embodiment, the second circuit 32 in the detection device 30 is exemplified by a configuration in which one push button switch 52 and two contact terminals 57 and 58 are provided. You may employ | adopt the structure which integrated one side. That is, the upper part of the push button type switch is configured as a contact terminal that can come into contact with the contact terminal 43 (44) of the first circuit 31, and the push button type switch is pushed downward by the web unit 20 being mounted. In some cases, the second circuit 32 may be disconnected. In this case, the number of parts can be reduced.

  Furthermore, in the first embodiment, the power supply 36 in the detection device 30 is exemplified as a configuration integrated with the detection unit 35. However, in addition to this, for example, the image forming apparatus main body side that uses the fixing device 1 is used. You may comprise so that a power supply may be utilized. In this configuration, when it is detected in the detection device 30 that the web unit 20 is not mounted as described above (the detection circuit 33 is in an energized state), for example, the image forming apparatus main body side The power supply from the power source to the detection circuit 33 may be set to be stopped.

FIG. 2 is a schematic cross-sectional view showing a main part of the fixing device according to Embodiment 1 of the present invention. FIG. 2 is a schematic cross-sectional view showing a state where a web unit is removed from the fixing device of FIG. 1. It is a perspective view which shows a web unit (the state turned over) and a part of detection apparatus. It is a schematic sectional drawing which shows the other part of a detection apparatus. It is explanatory drawing which shows the operation state of the switch of a 1st circuit. It is a circuit diagram which shows a structure when the detection apparatus is in a non-energized state. It is a circuit diagram which shows a structure when it exists in the partial non-conduction state (energization state) of a detection apparatus. It is a block diagram which shows the structure of the main control system when the detection part of a detection apparatus is connected to the central control part. It is a flowchart which shows operation | movement of a detection apparatus and a central control part. It is explanatory drawing which shows the state of a detection apparatus when a web unit is not mounted | worn. It is explanatory drawing which shows the state of a detection apparatus when a web unit is mounted | worn and there exists a cleaning web. It is explanatory drawing which shows the state of a detection apparatus when a web unit is mounted | worn and there is no cleaning web.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fixing apparatus, 10 ... Main part of apparatus, 11 ... Fixing roll (rotating body for fixing), 12 ... Pressure roll (rotating body for fixing), 20 ... Web unit, 21 ... Cleaning web, 23 ... Shaft for delivery, 25 ... take-up shaft, 30 ... detection device, 31 ... first circuit, 32 ... second circuit, 33 ... detection circuit, 36 ... same power source, 41, 42 ... leaf spring type switch (switch of first circuit) , 52... Push button type switch (second circuit switch), T... Toner image, P... Recording paper (recording medium).

Claims (4)

An apparatus main body including a fixing rotator for fixing an unfixed toner image on a recording medium;
A long cleaning web, which is detachably attached to the main body of the apparatus and cleans the fixing rotating body, is sent out from a state where it is wound around the feeding shaft and brought into contact with a portion to be cleaned of the fixing rotating body, and then wound up. A web unit comprising a structure wound around a shaft,
A first circuit provided with a switch that operates according to the presence state of an unused cleaning web in the web unit and a second circuit provided with a switch that operates according to the attachment / detachment state of the web unit are connected in parallel. Detection to detect the presence or absence of the web and whether or not the web unit is mounted by detecting whether the entire circuit is in a conductive state or a non-conductive state when power is supplied to the detection circuit. And a fixing device.   In the detection device, when there is a cleaning web, the switch of the first circuit cuts off the circuit, and when the web unit is mounted, the switch of the second circuit cuts off the circuit. The fixing device according to claim 1, wherein the fixing device is set as follows.   The detection device determines that there is no usable cleaning web in the web unit when the entire detection circuit changes from a non-conductive state to a conductive state during power supply, and the power to the detection circuit is determined. The fixing device according to claim 2, wherein the fixing device is set to stop supply.   As the switch of the first circuit, while using an unused cleaning web, the circuit is cut off, while the web is not used, the mechanism is connected to the circuit. And as a switch of the second circuit, when the web unit is attached to the apparatus main body, the circuit is cut off in conjunction with it, while when the unit is removed from the apparatus main body, the circuit is connected in conjunction with it. The fixing device according to claim 1, wherein a fixing mechanism is used.

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