JP5856942B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a fixing device that fixes a toner image on a sheet and an image forming apparatus including the fixing device.

  2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine is provided with a fixing device for fixing a toner image on a sheet. The fixing device generally employs a heat fixing method in which toner is fixed to a sheet by heat. Such a heat-fixing type fixing device includes a fixing member (for example, a fixing roller or a fixing belt) for fixing a toner image on a sheet and a heat source (for example, a halogen heater or a ceramic heater) for heating the fixing member. Is provided.

  In the fixing device having such a configuration, a fixing mode in which the fixing member is heated to a fixing temperature capable of fixing the toner image on the sheet, and the fixing member is heated to a power saving temperature lower than the fixing temperature described above. In some cases, the power saving mode can be switched between the power saving mode and the sleep mode in which the fixing member is not heated. In the case of adopting such a configuration, when shifting from the fixable mode to the power saving mode or when shifting from the power saving mode to the sleep mode, heating of the fixing member by the heat source is stopped, and the temperature of the fixing member decreases. Usually, the heat corresponding to the temperature drop becomes waste heat and is discharged outside the apparatus, so that energy is wasted.

  Therefore, in order to effectively use this wasted energy, Patent Document 1 discloses waste heat of the fixing member by a thermoelectric conversion device provided adjacent to the fixing member (see “fixing roller 1”). A configuration for converting to electrical energy is disclosed. Patent Document 1 discloses that a thermoelectric conversion device is not adjacent to a fixing member when performing a fixing operation (an operation for fixing a toner image on a sheet of paper). A configuration in which the conversion device is adjacent to the fixing member is disclosed (see paragraph 0022).

JP 2004-133340 A

  For example, at the time of Ready waiting in the above-described fixing possible mode, it is necessary to heat the fixing member to a fixing possible temperature even if the fixing operation is not performed. In the power saving mode described above, it is necessary to heat the fixing member to the power saving temperature in preparation for the next fixing operation even if the fixing operation is not performed. However, in Patent Document 1, since the thermoelectric conversion device is uniformly adjacent to the fixing member when the fixing operation is not performed, the heat of the fixing member is deprived by the thermoelectric conversion device even in the Ready or power saving mode. It will be broken. Therefore, there is a problem that the temperature of the fixing member tends to be lower than the fixable temperature during Ready, and it takes time to raise the temperature of the fixing member to the fixable temperature when returning from the power saving mode to the fixable mode. There is a problem of end.

  In view of the above circumstances, the present invention makes it possible to recover waste heat of the fixing member and use it as electric energy, and to prevent the heat of the fixing member from being taken away during heating of the fixing member. The purpose is to do.

  The fixing device of the present invention includes a fixing member that fixes a toner image on a sheet, a heat source that heats the fixing member, a thermoelectric conversion device that converts heat generated from the fixing member into electricity, a first position, A drive mechanism that moves the thermoelectric converter between a second position that is closer to the fixing member than the first position, a control unit that is capable of transmitting a drive command signal to the drive mechanism, and A storage unit that stores a heating target temperature of the fixing member, and the control unit moves the thermoelectric conversion device to the first position while the heat source is heating the fixing member to the heating target temperature. The thermoelectric conversion device is moved from the first position to the second position by the drive mechanism as the heat source stops heating the fixing member.

  By adopting such a configuration, while the heat source is heating the fixing member to the heating target temperature, the thermoelectric conversion device is held in the first position regardless of whether or not the fixing operation is performed. Is possible. Therefore, it is possible to prevent the heat of the fixing member from being taken away by the thermoelectric conversion device during heating of the fixing member. On the other hand, as the heat source stops heating the fixing member, the thermoelectric conversion device is moved to the second position closer to the fixing member than the first position. Waste heat can be efficiently recovered and converted into electrical energy. Therefore, a fixing device with high energy saving can be provided.

  The storage unit stores a fixing possible temperature at which a toner image can be fixed on a sheet and a power saving temperature lower than the fixing possible temperature as the heating target temperature, and the heat source can fix the fixing member. A transition from a fixable mode that heats to a temperature to a power saving mode that heats the fixing member to the power saving temperature, and a transition from the fixable mode or the power saving mode to a sleep mode that does not heat the fixing member. The heating of the fixing member may be stopped when starting and when the power is turned off.

  By adopting such a configuration, it becomes possible to more efficiently convert the exhaust heat generated when the temperature of the fixing member is lowered into electric energy.

  The fixing device of the present invention further includes a temperature detection unit that detects a temperature of the fixing member, and the control unit starts the transition from the fixing possible mode to the power saving mode, and then performs the fixing by the temperature detection unit. It is determined whether or not the detected temperature of the member has decreased to the power saving temperature, and when it is determined that the detected temperature has decreased to the power saving temperature, the thermoelectric conversion device is moved to the second by the drive mechanism. It is also possible to move from the position to the first position.

  By adopting such a configuration, it is possible to prevent the temperature of the fixing member from lowering than the power saving temperature in the power saving mode. Accordingly, when returning from the power saving mode to the fixable mode, the temperature of the fixing member can be quickly raised to the fixable temperature.

  The drive mechanism includes a rotation shaft to which the thermoelectric conversion device is fixed along the longitudinal direction of the fixing member, and a motor connected to the rotation shaft. When the motor is rotated, the thermoelectric conversion device May rotate around the rotation axis.

  By adopting such a configuration, it is possible to move the thermoelectric conversion device using a drive mechanism with a simple configuration.

  The drive mechanism includes a support member that extends in a direction perpendicular to the longitudinal direction of the fixing member and supports the thermoelectric conversion device, and a motor connected to the support member, and when the motor is rotated, The thermoelectric conversion device may slide in the direction perpendicular to the longitudinal direction of the fixing member together with the support member.

  By adopting such a configuration, the moving distance of the thermoelectric conversion device can be sufficiently secured, and the heat of the fixing member is more reliably prevented from being taken away by the thermoelectric conversion device during heating of the fixing member. be able to.

  The motor drive circuit may be a discharge circuit of a smoothing capacitor provided in the power supply unit.

  By adopting such a configuration, unnecessary electric energy generated on the power supply unit side can be used as a drive source of the motor, and the fixing device can further save energy.

  The thermoelectric conversion device may be provided apart from the fixing member in a state in the second position.

  By adopting such a configuration, it is possible to prevent the surface of the fixing member from being damaged by the thermoelectric conversion device.

  The thermoelectric conversion device may be disposed outside the fixing member.

  By adopting such a configuration, the temperature difference between the heat receiving side and the heat radiating side of the thermoelectric conversion device can be increased compared to the case where the thermoelectric conversion device is arranged inside the fixing member. It becomes possible to improve the power generation efficiency.

  The image forming apparatus of the present invention includes any one of the fixing devices described above.

  According to the present invention, waste heat of the fixing member can be recovered and used as electric energy, and it is possible to prevent the heat of the fixing member from being deprived during heating of the fixing member. Become.

1 is a schematic diagram illustrating an outline of a multifunction peripheral according to a first embodiment of the present invention. 1 is a perspective view illustrating a fixing device of a multifunction peripheral according to a first embodiment of the present invention. 1 is a block diagram illustrating a configuration of a fixing device of a multifunction peripheral according to a first embodiment of the present invention. 3 is a flowchart illustrating control of the fixing device of the multifunction peripheral according to the first embodiment of the present invention. 6 is a graph showing the relationship between the temperature T of the fixing roller and the elapsed time t in the fixing device of the multifunction peripheral according to the first embodiment of the present invention. FIG. 6 is a perspective view illustrating a fixing device of a multifunction peripheral according to a second embodiment of the present invention.

<First Embodiment>
First, the overall configuration of a multifunction machine 1 as an image forming apparatus will be described with reference to FIG. FIG. 1 is a schematic diagram showing an outline of a multifunction peripheral according to the first embodiment of the present invention.

  The multifunction device 1 includes a box-shaped multifunction device main body 2. A paper feed cassette 3 that stores paper (not shown) is provided at the lower portion of the multifunction device main body 2. Is provided with a paper discharge tray 4.

  An intermediate transfer unit 5 is provided on the upper part of the multifunction machine main body 2. The intermediate transfer unit 5 includes an intermediate transfer belt 6 installed between a plurality of rollers. An exposure unit 7 including a laser scanning unit (LSU) is disposed below the intermediate transfer belt 6. ing. Four image forming portions 8 are provided for each toner color along the lower portion of the intermediate transfer belt 6 in the central portion of the multifunction device main body 2.

  Each image forming unit 8 is rotatably provided with a photosensitive drum 9, and around the photosensitive drum 9, a charger 10, a developing unit 11, a primary transfer unit 12, and a cleaning device 13 are provided. The static eliminator 14 is arranged in the order of the primary transfer process. Above the developing unit 11, four toner containers 15 corresponding to the image forming units 8 are provided for each toner color.

  A sheet conveyance path 16 is provided on one side (right side in the drawing) of the multifunction machine main body 2. A paper feed unit 17 is provided at the upstream end of the conveyance path 16, and a secondary transfer unit 18 is provided at one end (right end in the drawing) of the intermediate transfer belt 6 at a middle portion of the conveyance path 16, and downstream of the conveyance path 16. The fixing device 20 is provided in the section, and a paper discharge port 21 is provided at the downstream end of the transport path 16.

  Next, an image forming operation of the multifunction machine 1 having such a configuration will be described. When the MFP 1 is turned on, various parameters are initialized, and initial settings such as temperature setting of the fixing device 20 are executed. When image data is input from a computer or the like connected to the multifunction machine 1 and an instruction to start printing is given, an image forming operation is executed as follows.

  First, after the surface of the photosensitive drum 9 is charged by the charger 10, the photosensitive drum 9 is exposed according to the image data by the laser light (see arrow P) from the exposure device 7, and the photosensitive member is exposed. An electrostatic latent image is formed on the surface of the drum 9. Next, the developing device 11 develops the electrostatic latent image into a toner image of a corresponding color with toner. This toner image is primarily transferred to the surface of the intermediate transfer belt 6 in the primary transfer portion 12. Each image forming unit 8 sequentially repeats the above operation, whereby a full-color toner image is formed on the intermediate transfer belt 6. Note that the toner and charge remaining on the photosensitive drum 9 are removed by the cleaning device 13 and the static eliminator 14.

  On the other hand, the paper taken out from the paper feed cassette 3 or the hand tray (not shown) by the paper feed unit 17 is conveyed to the secondary transfer unit 18 in synchronization with the above-described image forming operation, and is subjected to secondary transfer. In the portion 18, the full-color toner image on the intermediate transfer belt 6 is secondarily transferred to the paper. The sheet on which the toner image is secondarily transferred is conveyed downstream in the conveyance path 16 and enters the fixing device 20, and the toner image is fixed on the sheet in the fixing device 20. The sheet on which the toner image is fixed is discharged from the discharge outlet 21 onto the discharge tray 4.

  Next, the configuration of the fixing device 20 will be described mainly with reference to FIG. Note that arrows Fr, Rr, L, and R in FIG. 2 respectively indicate the front, rear, left, and right sides of the fixing device 20 (the same applies to FIG. 6).

  The fixing device 20 is unitized and can be attached to and detached from the multifunction machine main body 2 (see FIG. 1). The fixing device 20 includes a fixing roller 22 as a fixing member, a pressure roller 23 disposed behind the fixing roller 22 so as to face the fixing roller 22, and a thermoelectric conversion device 24 disposed above and in front of the fixing roller 22. And a drive mechanism 25 disposed in front of and above the fixing roller 22 together with the thermoelectric converter 24. Hereinafter, these will be described in order.

  First, the fixing roller 22 will be described. The fixing roller 22 has a long shape in the left-right direction. That is, in the present embodiment, the left-right direction is the longitudinal direction of the fixing roller 22. The fixing roller 22 includes, for example, a cylindrical core material made of a metal such as aluminum or iron, an elastic layer made of silicon rubber or the like provided around the core material, and a fluorine resin such as PFA covering the elastic layer. And a release layer. The fixing roller 22 is rotatably supported by a fixing frame (not shown).

  In the inner space of the fixing roller 22, a heater 26 as a heat source configured by, for example, a halogen heater or a ceramic heater is accommodated. A thermistor 27 serving as a temperature detection unit for detecting the temperature of the fixing roller 22 is disposed above the fixing roller 22. The thermistor 27 may be in contact with the outer peripheral surface of the fixing roller 22 or may not be in contact.

  Next, the pressure roller 23 will be described. Similar to the fixing roller 22, the pressure roller 23 has a shape that is long in the left-right direction. The pressure roller 23 includes, for example, a cylindrical core material made of a metal such as aluminum or iron, an elastic layer made of silicon rubber or the like provided around the core material, and a fluorine such as PFA covering the elastic layer. And a release layer made of resin. Similar to the fixing roller 22, the pressure roller 23 is rotatably supported by a fixing frame (not shown).

  The pressure roller 23 is in pressure contact with the fixing roller 22 by an urging force of an urging means (not shown), and a fixing nip 28 is formed between the fixing roller 22 and the pressure roller 23. The pressure roller 23 is configured to be driven and rotated in the opposite direction to the fixing roller 22 as the fixing roller 22 rotates (see arrows a and b in FIG. 2).

  Next, the thermoelectric conversion device 24 will be described. The thermoelectric converter 24 is disposed outside the fixing roller 22 and has a flat plate shape that is long in the left-right direction (longitudinal direction of the fixing roller 22) as a whole. The thermoelectric conversion device 24 is configured by connecting a plurality of (for example, seven) plate-like thermoelectric conversion modules 30 in series. One surface of each thermoelectric conversion module 30 is a heat receiving surface 31, and the other surface of each thermoelectric conversion module 30 is a heat radiating surface 32. A pair of semiconductor elements (n-type semiconductor element and p-type semiconductor element) are arranged in each thermoelectric conversion module 30. When a temperature difference occurs at the junction of the pair of semiconductor elements, a so-called Seebeck effect occurs. It is configured to generate electric power.

  Next, the drive mechanism 25 will be described. The drive mechanism 25 includes a rotation shaft 33 and a motor 34 disposed on the left end side of the rotation shaft 33.

  The rotating shaft 33 has a straight rod shape that is long in the left-right direction. A side surface (a surface perpendicular to the heat receiving surface 31 and the heat radiating surface 32 and extending in the left-right direction) of the thermoelectric conversion device 24 is fixed to the rotating shaft 33 along the left-right direction. A driven gear 35 is coaxially fixed to the left end portion of the rotation shaft 33.

  The motor 34 is, for example, a stepping motor, and is provided so as to be able to rotate forward and reverse. A driving gear 36 is fixed to the motor 34, and the motor 34 is connected to the rotating shaft 33 by meshing with the driven gear 35 fixed to the rotating shaft 33. When the motor 34 is rotated, this rotation is transmitted to the thermoelectric conversion device 24 via the rotation shaft 33, and the thermoelectric conversion device 24 rotates within a predetermined angle range around the rotation shaft 33. . With this rotation, the thermoelectric conversion device 24 has a first position (see a solid line in FIG. 2) that is spaced apart from the fixing roller 22 by a predetermined distance, and a second position that is closer to the fixing roller 22 than the first position. (See the two-dot chain line in FIG. 2). Hereinafter, the rotation direction (the arrow X direction in FIG. 2) for moving the thermoelectric conversion device 24 from the second position to the first position is referred to as a positive direction, and the thermoelectric conversion device 24 is moved from the first position to the second position. The direction of rotation (the direction opposite to the arrow X in FIG. 2) is referred to as the reverse direction.

  The thermoelectric conversion device 24 is in the second position and is separated from the fixing roller 22. In other words, the thermoelectric conversion device 24 is in the second position and is not in contact with the fixing roller 22.

  Next, a control system of the fixing device 20 will be described with reference to FIG.

  The fixing device 20 is provided with a control unit 37 (CPU). The control unit 37 is connected to a storage unit 38 configured by a storage device such as a ROM or a RAM. The control unit 37 is connected to the fixing device 20 based on a control program or control data stored in the storage unit 38. It is configured to control each part. The storage unit 38 has a fixing temperature at which the toner image can be fixed on the paper (200 ° C. in the present embodiment) and a power saving temperature (100 ° C. in the present embodiment) lower than the fixing possible temperature. 22 as the heating target temperature.

  The control unit 37 is connected to the thermistor 27. Then, the controller 37 receives the temperature of the fixing roller 22 detected by the thermistor 27.

  The control unit 37 is connected to the heater 26. The fixing roller 22 is heated by the heater 26 when the heater 26 is energized and generates heat based on a signal from the control unit 37.

  The control unit 37 is connected to the capacitor 40 (power storage unit). The capacitor 40 is connected to the thermoelectric conversion device 24 via the power storage device 41, and the electrical energy converted from the thermal energy by the thermoelectric conversion device 24 is stored in the capacitor 40 by the power storage device 41. . The control unit 37 monitors the amount of stored electricity.

  The controller 37 is connected to the drive motor 43 via the first drive circuit 42, and the drive motor 43 is connected to the fixing roller 22. Then, based on a drive command signal from the control unit 37, a current is passed from the first drive circuit 42 to the drive motor 43, whereby the drive motor 43 rotates, and this rotation is transmitted to the fixing roller 22 to be fixed to the fixing roller. 22 is configured to rotate.

  The control unit 37 is connected to the motor 34 of the drive mechanism 25 via the second drive circuit 44. The motor 34 is configured to rotate when a current is passed from the second drive circuit 44 to the motor 34 based on a drive command signal (pulse signal) from the control unit 37. That is, the control part 37 is provided so that the drive command signal to the drive mechanism 25 can be transmitted. The second drive circuit 44 is a discharge circuit of a smoothing capacitor 46 provided in a power supply unit 45 (cut-off power supply) that supplies power to each unit of the multifunction machine 1.

  A control method of the fixing device 20 configured as described above will be described mainly with reference to FIGS.

  First, when a user or the like turns on the multifunction device 1 (step S101), the control unit 37 causes a current to flow from the second drive circuit 44 to the motor 34, and rotates the motor 34 in one direction by a predetermined angle. This rotation is transmitted to the thermoelectric conversion device 24 via the rotating shaft 33, and the thermoelectric conversion device 24 rotates in the positive direction (see arrow X in FIG. 2) from the second position to the first position (step S102). ). At this time, the temperature of the fixing roller 22 remains at room temperature (at time t1 in FIG. 5).

  When step S102 ends, the control unit 37 heats the fixing roller 22 with the heater 26 (step S103). By this heating, the temperature of the fixing roller 22 rises from the normal temperature to the fixable temperature (200 ° C.) (time t2 in FIG. 5).

  Next, the control unit 37 shifts to the fixable mode (S104). If there is a print instruction from a computer (not shown) or the like, the control unit 37 transmits a drive command signal from the first drive circuit 42 to the drive motor 43 to rotate the fixing roller 22. When the fixing roller 22 rotates in this manner, the pressure roller 23 is also rotated in accordance with this rotation, and the toner image is fixed on the paper that has entered the fixing nip 28. On the other hand, if there is no instruction for printing from a computer (not shown) or the like, the apparatus stands by in a Ready state (a state where printing can be started at any time). In this fixable mode, the heater 26 continues to heat the fixing roller 22 to a fixable temperature, and the thermoelectric conversion device 24 is held in the first position during that time.

  Next, the control unit 37 determines whether or not to shift from the fixable mode to the power saving mode (step S105). This determination is performed based on, for example, whether a predetermined time has passed in the Ready state or whether the user has selected the power saving mode. When the determination in step S105 is NO, the control unit 37 performs the fixing operation in the fixing possible mode or waits in the ready state (step S104).

  On the other hand, when the determination in step S105 is YES, the transition from the fixing possible mode to the power saving mode is started, and the control unit 37 stops the heating of the fixing roller 22 by the heater 26. Along with this, the temperature of the fixing roller 22 starts to decrease from the fixing possible temperature (200 ° C.) (time t3 in FIG. 5).

  When the transition to the power saving mode is started as described above, the control unit 37 causes a current to flow from the second drive circuit 44 to the motor 34 and rotates the motor 34 by a predetermined angle in a direction opposite to the one direction. Let Along with this, the thermoelectric conversion device 24 rotates in the reverse direction (the direction opposite to the arrow X in FIG. 2) from the first position to the second position (step S107). By this rotation, the thermoelectric conversion device 24 approaches the fixing roller 22, and the heat receiving surface 31 of each thermoelectric conversion module 30 of the thermoelectric conversion device 24 faces the outer peripheral surface of the fixing roller 22. Then, the thermoelectric conversion device 24 converts the heat energy generated from the fixing roller 22 into electric energy. This electrical energy is stored in the capacitor 40 by the power storage device 41.

  Next, the control unit 37 determines whether or not the detected temperature of the fixing roller 22 by the thermistor 27 is lowered to the power saving temperature (100 ° C.) (step S108). When the determination in step S108 is NO, the determination in the output step S108 is repeated each time the detected temperature of the fixing roller 22 is output from the thermistor 27. On the other hand, when it is determined that the temperature of the fixing roller 22 has decreased to the power saving temperature (100 ° C.) (at time t4 in FIG. 5), the control unit 37 supplies a current from the second drive circuit 44 to the motor 34. The motor 34 is rotated by a predetermined angle in one direction. Along with this, the thermoelectric converter 24 rotates in the forward direction (see arrow X in FIG. 2) from the second position to the first position (step S109).

  As described above, when the temperature of the fixing roller 22 reaches the power saving temperature (100 ° C.), the control unit 37 shifts to the power saving mode (step S110). In this power saving mode, the fixing roller 22 is heated to the power saving temperature by the heater 26. In order to heat the fixing roller 22 to the power saving temperature, for example, the current flowing through the heater 26 is reduced as compared with the fixable mode, or the ratio of the OFF time to the ON time of the heater 26 is increased compared with the fixable mode. good.

  Next, the control unit 37 determines whether to shift from the power saving mode to the sleep mode (a mode in which the fixing roller 22 is not heated by the heater 26) or to turn off the power of the multifunction machine 1 (step S111). ). The determination whether to shift from the power saving mode to the sleep mode is performed based on, for example, whether or not a predetermined time has passed in the power saving mode. The determination as to whether to turn off the power of the multifunction device 1 is made based on, for example, whether or not the power switch has been switched from ON to OFF by the user. When the determination in step S111 is NO, the control unit 37 stands by in the power saving mode (step 110).

  On the other hand, if the determination in step S111 is YES, the transition from the power saving mode to the sleep mode is started, or the power is turned off, and the heater 26 stops heating the fixing roller 22 (step S112). ). Along with this, the temperature of the fixing roller 22 starts to decrease from the power saving temperature (100 ° C.) (at time t5 in FIG. 5).

  Further, the control unit 37 causes a current to flow from the second drive circuit 44 to the motor 34, and rotates the motor 34 by a predetermined angle in a direction opposite to the one direction. Along with this, the thermoelectric converter 24 rotates in the reverse direction (the direction opposite to the arrow X in FIG. 2) from the first position to the second position (step S113). Thereby, the thermoelectric conversion device 24 approaches the fixing roller 22, and the heat receiving surface 31 of each thermoelectric conversion module 30 of the thermoelectric conversion device 24 faces the outer peripheral surface of the fixing roller 22. Then, the thermoelectric conversion device 24 converts the heat energy generated from the fixing roller 22 into electric energy. This electrical energy is stored in the capacitor 40 by the power storage device 41. If the fixing device 20 is left with the heating of the fixing roller 22 stopped by the heater 26 as described above, the temperature of the fixing roller 22 is normal temperature (a sufficient time has passed since the heating of the fixing roller 22 was stopped). , The temperature when the temperature drop of the fixing roller 22 stops) (time t6 in FIG. 5).

  For example, when a printing instruction is given from a computer (not shown) during the sleep mode, or when the power switch is turned on by the user or the like from a power-off state, the control unit 37 enters the fixing-possible mode. Is started (step S114). In this case, returning to step S102, the thermoelectric converter 24 is rotated in the forward direction (see arrow X in FIG. 2) from the second position to the first position. If the return to the fixable mode is not started in step S114, the control of the fixing device 20 is ended.

  In the present embodiment, as described above, while the heater 26 is heating the fixing roller 22 to the heating target temperature (the fixing possible temperature and the power saving temperature in the present embodiment), the thermoelectric conversion device 24 is set to the first position. The thermoelectric conversion device 24 is moved from the first position to the second position by the drive mechanism 25 as the heater 26 stops heating the fixing roller 22. By adopting such a configuration, while the heater 26 is heating the fixing roller 22 to the heating target temperature, the thermoelectric conversion device 24 is set to the first position regardless of whether or not the fixing operation is performed. It becomes possible to hold. Therefore, the heat of the fixing roller 22 can be prevented from being taken away by the thermoelectric conversion device 24 during the heating of the fixing roller 22. On the other hand, as the heater 26 stops heating the fixing roller 22, the thermoelectric conversion device 24 is moved to the second position closer to the fixing roller 22 than the first position. Therefore, the waste heat of the fixing roller 22 can be efficiently recovered by the thermoelectric conversion device 24 and converted into electric energy. Therefore, it is possible to provide the fixing device 20 with high energy saving performance.

  Further, when the fixing operation is performed, the thermoelectric conversion device 24 is in the first position, and the heat of the fixing roller 22 is not deprived by the thermoelectric conversion device 24. Therefore, the fixing roller 22 is stably heated to a fixable temperature. It is possible to prevent image defects from occurring.

  In addition, the heater 26 stops heating the fixing roller 22 when shifting from the fixing possible mode to the power saving mode, when shifting from the power saving mode to the sleep mode, or when the power is turned off. By adopting such a configuration, it becomes possible to more efficiently convert the exhaust heat generated when the temperature of the fixing roller 22 is lowered into electric energy. Note that heating of the fixing roller 22 by the heater 26 is also stopped when shifting from the fixable mode to the sleep mode without passing through the power saving mode or when the power is turned off.

  Further, the control unit 37 determines whether or not the detected temperature of the fixing roller 22 by the thermistor 27 has decreased to the power saving temperature after starting the transition from the fixing possible mode to the power saving mode, and the detected temperature is the power saving temperature. If it is determined that the temperature has decreased, the thermoelectric conversion device 24 is moved from the second position to the first position by the drive mechanism 25. By adopting such a configuration, it is possible to prevent the heat of the fixing roller 22 from being taken away by the thermoelectric conversion device 24 in the power saving mode and the temperature of the fixing roller 22 being lower than the power saving temperature. Accordingly, when returning from the power saving mode to the fixable mode, the temperature of the fixing roller 22 can be quickly raised to the fixable temperature.

  The drive mechanism 25 includes a rotation shaft 33 and a motor 34, and the thermoelectric conversion device 24 is configured to rotate about the rotation shaft 33 when the motor 34 is rotated. By adopting such a configuration, it is possible to move the thermoelectric conversion device 24 using the drive mechanism 25 having a simple configuration.

  The second drive circuit 44, which is a drive circuit for the motor 34, is a discharge circuit for the smoothing capacitor 46 provided in the power supply unit 45. Therefore, unnecessary electrical energy generated on the power supply unit 45 side can be used as a drive source of the motor 34, and the fixing device 20 can be further saved in energy.

  Further, since the thermoelectric conversion device 24 is in the second position and is separated from the fixing roller 22, it is possible to prevent the surface of the fixing roller 22 from being damaged by the thermoelectric conversion device 24. .

  By the way, in order to increase the power generation efficiency by the thermoelectric conversion device 24, a temperature difference is required. However, since heat easily accumulates in the fixing roller 22, even if the thermoelectric conversion device 24 is arranged inside the fixing roller 22. The power generation efficiency is bad. On the other hand, in this embodiment, since the thermoelectric conversion device 24 is arranged outside the fixing roller 22, high power generation efficiency can be expected.

  Next, an example of a method for calculating the power gain when using the thermoelectric conversion device 24 as described above will be described.

The specification of the assumed thermoelectric conversion module 30 is as follows.
Module size 50mm x 50mm x 4.2mm
Module weight 47g
Energy conversion efficiency 7.2% (when operating at 280 ° C on the high temperature side and 30 ° C on the low temperature side)
Maximum output 24W (same as above)
Output density 1W / cm ² (same as above)

Assuming that the length of the fixing roller 22 is 336 mm, for example, if the seven thermoelectric conversion modules 30 (left and right width 50 mm) are connected in series, the left and right width of the entire thermoelectric converter 24 is
50 × 7 = 350mm
Thus, the thermoelectric conversion device 24 can be arranged from one end to the other end of the fixing roller 22 in the longitudinal direction. In this case, the maximum output of the thermoelectric converter 24 is
24 × 7 = 168W
It becomes.

On the other hand, the overall weight of the thermoelectric converter 24 is
47 × 7 = 329g = 0.329kg
And in order to move this,
0.329 × 9.8 = 3.22N
The power of Therefore, the motor 34 with power consumption of 12 W is used.

It takes about 40 minutes for the fixing roller 22 to reach the normal temperature from the fixable temperature. During this time, the power (amount) obtained by thermoelectric conversion is
(40/60) × 168 = 112 W · h
It becomes.

Assuming that the temperature of the fixing roller 22 decreases in a curved line and assuming that the actual thermoelectric conversion efficiency is halved, the electric power (amount) converted into thermoelectric power is
112/2 = 56W · h
It becomes. When the fixing mode is shifted directly to the sleep mode, the motor 34 is moved a total of two times when the temperature of the fixing roller 22 starts to decrease and when the temperature of the fixing roller 22 has decreased to room temperature. If the time for moving the motor 34 is 3 seconds, the power consumption is
2 × 12 × (3/3600) = 0.02W · h
It becomes.

The power gain in this case is
56−0.02 = 55.98W ・ h
Is calculated. In addition, when shifting from the fixing possible mode to the sleep mode through the power saving mode, the motor 34 is moved a total of four times. The power gain can be calculated based on the same principle.

  In the present embodiment, the case where the thermoelectric conversion device 24 is rotated from the first position to the second position after stopping the heating of the fixing roller 22 has been described (see Step S106 and Step S107). On the other hand, in another different embodiment, heating of the fixing roller 22 may be stopped after the thermoelectric conversion device 24 is rotated from the first position to the second position.

  In the present embodiment, a capacitor is used as a power storage unit for electrical energy converted by the thermoelectric conversion device 24. However, in another different embodiment, a secondary battery may be used as a power storage unit.

  Although the case where the heater 26 is used as the heat source has been described in the present embodiment, other heat sources such as an IH coil may be used in other different embodiments.

  In this embodiment, the case where the configuration of the present invention is applied to the multi-function device 1 has been described. However, in another different embodiment, the configuration of the present invention is applied to other image forming apparatuses such as a printer, a copier, and a facsimile. It is also possible.

<Second Embodiment>
Next, a fixing device 51 according to a second embodiment of the present invention will be described with reference to FIG. In addition, since it is the structure similar to 1st Embodiment about parts other than the drive mechanism 52, the same number as 1st Embodiment is attached | subjected on drawing, and description is abbreviate | omitted.

  The drive mechanism 52 includes a pair of left and right support members 53 and a pair of left and right motors 54 disposed in the vicinity of each support member 53.

  The support member 53 extends in the front-rear direction (a direction perpendicular to the left-right direction, which is the longitudinal direction of the fixing roller 22), and has a straight bar shape. The right end thermoelectric conversion module 30 is fixed to the rear end portion of the right support member 53. The left end thermoelectric conversion module 30 is fixed to the rear end portion of the left support member 53. With such a configuration, the thermoelectric conversion device 24 is supported by the pair of left and right support members 53. A rack 55 is provided on the upper surface of each support member 53. The rack 55 is formed by arranging a large number of gears in a straight line, but the description of gears is omitted in the drawing of FIG.

  Each motor 54 is, for example, a stepping motor, and is provided so as to be able to rotate forward and backward. A pinion 56 is fixed to each motor 54, and the rack and pinion mechanism 57 is formed by engaging the pinion 56 with the rack 55 of each support member 53. In other words, each motor 54 is connected to each support member 53 via a rack and pinion mechanism 57.

  When each motor 54 rotates, this rotation is transmitted to each support member 53 via the rack and pinion mechanism 57, and each support member 53 slides linearly in the front-rear direction. Along with this slide, the thermoelectric conversion device 24, together with each support member 53, a first position (see a solid line in FIG. 6) that is separated from the fixing roller 22 by a predetermined distance, and the fixing roller more than the first position. It slides linearly in the front-rear direction between the second position approaching 22 (see the two-dot chain line in FIG. 6).

  By adopting such a configuration, a sufficient moving distance of the thermoelectric conversion device 24 can be ensured, and the heat of the fixing roller 22 is taken away by the thermoelectric conversion device 24 while the fixing roller 22 is heated. It can be surely prevented.

1 MFP (image forming device)
20 Fixing device 22 Fixing roller (fixing member)
24 Thermoelectric conversion device 25 Drive mechanism 26 Heater (heat source)
27 Thermistor (temperature detector)
33 Rotating shaft 34 Motor 37 Control unit 38 Storage unit 45 Power supply unit 46 Smoothing condenser 53 Support member 54 Motor 57 Rack and pinion mechanism

Claims (7)

A fixing member for fixing the toner image on the paper;
A heat source for heating the fixing member;
A thermoelectric conversion device that converts heat generated from the fixing member into electricity;
A drive mechanism that moves the thermoelectric conversion device between a first position and a second position that is closer to the fixing member than the first position;
A control unit capable of transmitting a drive command signal to the drive mechanism;
A storage unit for storing a heating target temperature of the fixing member;
A temperature detection unit for detecting the temperature of the fixing member ,
The controller holds the thermoelectric conversion device at the first position while the heat source is heating the fixing member to the heating target temperature, and the heat source stops heating the fixing member. Accordingly, the thermoelectric conversion device is moved from the first position to the second position by the drive mechanism ,
The storage unit stores, as the heating target temperature, a fixable temperature at which a toner image can be fixed on a sheet, and a power saving temperature lower than the fixable temperature,
The heat source starts the transition from the fixable mode in which the fixing member is heated to the fixable temperature to the power saving mode in which the fixing member is heated to the power saving temperature, and from the fixable mode or the power saving mode to the power saving mode. When the transition to the sleep mode without heating the fixing member is started and when the power is turned off, the heating of the fixing member is stopped,
The control unit determines whether the temperature detected by the temperature detection unit of the fixing member has decreased to the power saving temperature after starting the transition from the fixable mode to the power saving mode, and the detected temperature Is determined to have decreased to the power saving temperature , the fixing mechanism moves the thermoelectric conversion device from the second position to the first position by the drive mechanism . The drive mechanism is
A rotating shaft to which the thermoelectric conversion device is fixed along the longitudinal direction of the fixing member;
A motor connected to the rotating shaft,
The fixing device according to claim 1 , wherein when the motor is rotated, the thermoelectric conversion device rotates about the rotation shaft. The drive mechanism is
A support member that extends in a direction perpendicular to the longitudinal direction of the fixing member and supports the thermoelectric conversion device;
A motor connected to the support member,
The fixing device according to claim 1 , wherein when the motor is rotated, the thermoelectric conversion device slides in a direction perpendicular to a longitudinal direction of the fixing member together with the support member. The fixing device according to claim 2, wherein the motor drive circuit is a discharge circuit of a smoothing capacitor provided in a power supply unit. The thermoelectric conversion device, while in said second position, the fixing device according to any one of claims 1 to 4, characterized in that spaced apart from the fixing member. The thermoelectric conversion device, a fixing device according to any one of claims 1 to 5, characterized in that it is disposed outside the fixing member. An image forming apparatus characterized in that it comprises a fixing device according to any one of claims 1-6.

Images