JP2013033133A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus which prevents condensation inside the apparatus and shortens warm-up time while avoiding an increase in size as much as possible.SOLUTION: An image forming apparatus includes a fixing device which forms a fixing nip by pressing a pressure roller 42 onto a surface of a heat roller 40, and fixes a toner image carried on a recording sheet by passing the sheet through the fixing nip. The image forming apparatus further includes: multiple peltier elements 64A to 64E which respectively have cooling surfaces where temperature falls upon application of power and heating surfaces where temperature rises upon application of power, and are provided along a paper width direction with the heating surfaces facing the surface of the heating roller 40; a water guiding member 70 and a water receiving box 76 which collect water resulting from condensation due to cooling effect of the peltier elements 64A to 64E; and control means which controls timing of power supply of a secondary battery supplying power to the peltier elements 64A to 64E. The control means causes the secondary battery to supply power during warm-up of the heating roller 40 and during fixing operation of the fixing device.

Description

  The present invention relates to a copier or other image forming apparatus, and more particularly to an image forming apparatus including a fixing device that heats and fixes toner onto a recording sheet.

Conventionally, various improvements and improvements have been made in the fixing device-related technology, but this case targets the following two points as improvements and improvements.
The first point is the problem of condensation. That is, when the toner image electrostatically transferred to the recording sheet is fixed to the recording sheet, the recording sheet is heated at a high temperature (for example, 180 ° C.), so that moisture contained in the recording sheet evaporates. . The relatively high-temperature steam generated by evaporation is condensed particularly on the surface of the sheet metal member inside the image forming apparatus. For this reason, there arises a problem that rust is generated in the sheet metal member or an unused recording sheet gets wet due to water droplets attached to the sheet metal member.

  The second point is to shorten the warm-up time. The time required from the time when the image forming apparatus is turned on or after the return instruction is issued from the standby mode until the image can be formed (warm-up time), the heating roller in the fixing device is necessary for fixing. It is determined by the time to raise the temperature. Therefore, how to quickly raise the temperature of the heating roller in order to shorten the time is a problem.

The first point is solved by the following configuration in the image forming apparatus disclosed in Patent Document 1. The image forming apparatus includes a Peltier element having a cooling fin attached to a cooling surface. By de-energizing the Peltier element, the cooling fin is cooled, and dew condensation is caused by the cooling fin, thereby dehumidifying the inside of the apparatus.
The second point can be improved by using the fixing device disclosed in Patent Document 2. Patent Document 2 discloses a fixing device in which an auxiliary heating lamp is provided as an auxiliary heating unit in addition to a heat source such as a heater lamp provided in a hollow portion of a cylindrical heating roller, and opposed to the outer peripheral surface of the heating roller. An apparatus is disclosed. Therefore, when raising the temperature of the heating roller, it is possible to shorten the time until image formation is possible by heating the heating roller with the auxiliary heating lamp in addition to the hollow heater lamp. .

JP 2005-268584 A (Patent No. 4460928) Japanese Patent Laid-Open No. 11-95591 JP 2008-261528 A JP 2005-122904 A Japanese Patent Laid-Open No. 2005-071822

However, according to the above conventional technique, although both the first and second points can be improved and improved, it is necessary to provide a dedicated configuration for each improvement and improvement point. Therefore, the overall size of the image forming apparatus is increased.
The present invention has been made in view of the above-described problems, and an object of the present invention is to improve and improve the first and second points without causing an increase in the size of the image forming apparatus as much as possible.

  In order to achieve the above object, an image forming apparatus according to the present invention forms a fixing nip by pressing a pressing member on the surface of a heat fixing member, and passes a recording sheet carrying a toner image in the fixing nip. In the image forming apparatus including the fixing device for fixing, a cooling surface that lowers the temperature when energized and a heating surface that increases the temperature, with the heating surface facing the surface of the heating fixing member, A plurality of thermoelectric conversion elements arranged along the paper passing width direction, a recovery means for recovering water generated by condensation due to a cooling action of the thermoelectric conversion elements, a power supply means for supplying power to the plurality of thermoelectric conversion elements, Control means for controlling the timing of the power supply by the power supply means, and the control means supplies power to the power supply means during warm-up of the heat fixing member and during fixing operation by the fixing device. Characterized in that to.

Also, a cooling heat sink is provided in close contact with the cooling surfaces of the plurality of thermoelectric conversion elements, and the cooling heat sink is cooled via the cooling surface, thereby causing the condensation on the surface. Features. In this case, a water retention film may be formed on the dew condensation surface of the cooling heat sink.
The cooling heat sink comprises a box surrounding the plurality of thermoelectric conversion elements so that only the heating surface and the heating surface side end portion of the thermoelectric conversion element are exposed, and the recovery means includes the box A water receiving box provided below the body, and a water guide member that is attached to the outer surface of the box and guides water droplets attached to the outer surface due to condensation into the box. In this case, the water receiving box may be provided detachably with respect to the housing of the image forming apparatus.

  A plurality of humidity sensors provided at positions corresponding to each of the thermoelectric conversion elements in the sheet passing width direction, and the plurality of thermoelectric conversion elements are provided above the fixing nip; The power supply means individually supplies power to each of the thermoelectric conversion elements, and the control means further refers to the humidity detected by the humidity sensor, and the thermoelectric conversion element corresponding to the humidity sensor that has detected high humidity, The power supply amount is increased.

  According to the image forming apparatus having the above configuration, during the warm-up of the heat fixing member, the heat from the heating surface of the thermoelectric conversion element provided in a state where the heating surface faces the surface of the heat fixing member, Since the surface of the heat fixing member is heated, the warm-up time can be shortened. Further, during the fixing operation by the fixing device, water generated by condensation due to the cooling action of the thermoelectric conversion element is collected, so that the inside of the image forming apparatus can be dehumidified. In addition, since both the shortening of the warm-up time and the dehumidification in the image forming apparatus can be realized by the thermoelectric conversion element, the enlargement of the image forming apparatus can be prevented as much as possible as compared with the conventional case.

1 is a diagram showing a schematic configuration of an entire copying machine according to an embodiment. In the copying machine, the heating roller, the pressure roller, and the periphery thereof are viewed from a direction orthogonal to the longitudinal direction of the heating roller and the pressure roller. It is the figure which looked at the said heating roller, a pressure roller, and its periphery from the longitudinal direction of a heating roller and a pressure roller. (A) is a perspective view of a duct and a member attached to the duct, and (b) is a perspective view of a Peltier element. (A) is a figure which shows schematic structure of a main control part, (b) is a figure which shows a part of structure of the control part which a printer part has. 6 is a flowchart of a program executed in the printer unit. In the copying machine according to the second embodiment, the heating roller, the pressure roller, and the periphery thereof are viewed from a direction orthogonal to the longitudinal direction of the heating roller and the pressure roller. 6 is a diagram illustrating a part of a configuration of a control unit included in a printer unit of a copying machine according to Embodiment 2. FIG.

Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described by taking a copying machine as an example with reference to the drawings.
<Embodiment 1>
FIG. 1 is a diagram showing a schematic configuration of an entire digital copying machine (hereinafter simply referred to as “copying machine”) 2 according to the first embodiment.

The copying machine 2 is an apparatus for forming an image by an electrophotographic method. As shown in FIG. 1, the copying machine 2 is roughly divided and an image reader unit 4 for reading an original image and the read image are printed on a recording sheet and reproduced. And a printer unit 6.
The image reader unit 4 has an automatic document feeder 8, and the documents set on the document tray 10 of the automatic document feeder 8 are conveyed one by one to the reading position on the document glass table 12. The document conveyed to the reading position on the document glass table 12 is read by the image sensor 14 and image data is generated. The generated image data is stored in an image memory 118 (FIG. 5A) described later.

  Image data in the image memory 118 is read by a CPU 112 of a main control unit 110 described later and input to a laser control unit 16 provided in the printer unit 6. The laser control unit 16 generates a laser diode drive signal based on the image data, and causes a laser diode (not shown) to emit light. The laser beam L emitted from the laser diode performs exposure scanning on the surface (photosensitive surface) of the photosensitive drum 18 that rotates in the direction of the arrow.

  Around the photosensitive drum 18, a cleaning device 20, a charging device 22, a developing device 24, and a transfer device 26 are arranged. Before the exposure scanning, the photosensitive drum 18 is uniformly charged by the charging device 22 after the residual toner on the surface is removed by the cleaning device 20. When the uniformly charged photosensitive surface is exposed, an electrostatic latent image is formed, and the electrostatic latent image is visualized as a toner image by the developing device 24.

On the other hand, a recording sheet of a desired type and a desired size is fed from any of the first to third sheet feeding cassettes 28, 30, 32 and the manual feed tray 34, and the fed recording sheet is transferred to the transfer device 26. The toner image on the photosensitive drum 18 is transferred to the recording sheet by the action of the transfer device 26.
The recording sheet to which the toner image has been transferred is conveyed to the fixing device 38 by the conveyance belt 36. The fixing device 38 includes a cylindrical heating roller 40 that is a heat fixing member and a pressure roller 42 that is a pressing member. A heater lamp 44 as a heat source is built in the hollow portion of the heating roller 40. The pressure roller 42 is formed by forming an elastic layer made of silicone rubber or fluororesin on a metal cored bar outer peripheral surface. The pressure roller 42 is in pressure contact with the heating roller 40 by a pressure contact mechanism (not shown). Due to the pressure contact, a fixing nip is formed between the rollers 40 and 42. The recording sheet carrying the unfixed toner image is passed through the fixing nip, and the toner image is fixed on the recording sheet.

The surface temperature of the heating roller 40 is maintained at, for example, about 180 ° C. when the toner image is fixed (during the fixing operation of the fixing device 38).
Further, the copying machine 2 has a standby mode (energy saving mode) for maintaining the surface temperature of the heating roller 40 at 140 to 150 ° C. when image formation (copying) is not performed for a certain period of time.
The recording sheet on which the toner image has been fixed is discharged to a discharge tray 48 by a discharge roller 46.

The fixing device 38 is provided with a peripheral device, which will be described later.
In addition, the copying machine 2 includes an operation panel 50 at a position on the upper surface where it can be easily operated. The operation panel 50 includes a numeric keypad for setting the number of copies, a clear key for resetting the number of copies to “1”, and a start key for starting a copy operation (original reading operation and print operation). Etc.).

The copier 2 is also provided with a switch 52 on its side for turning on / off the power of the copier 2. Further, the copying machine 2 includes a secondary battery 130 that is a power supply unit that supplies power to Peltier elements 64A to 64E described later. The secondary battery 130 will be described later.
A peripheral device of the fixing device 38 will be described with reference to FIGS. 2, 3, and 4.
FIG. 2 is a view of the heating roller 40, the pressure roller 42, and the periphery thereof from a direction orthogonal to the longitudinal direction of the heating roller 40 and the pressure roller 42, and FIG. It is the figure which looked at the heating roller 40, the pressure roller 42, and its periphery from the longitudinal direction of the roller 42. FIG. In FIG. 3, a duct 54 and a frame 60 which will be described later are drawn by cutting.

Above the heating roller 40, a rectangular tube-shaped duct 54 is installed in parallel with the heating roller 40. The duct 54 is made of a material having excellent thermal conductivity, for example, aluminum. Both ends of the duct 54 are attached to the housing 56 of the copying machine 2, and openings at both ends are opened to the outside of the housing 56 (the copying machine 2).
A blowing fan 58 is provided in the vicinity of one opening of the duct 54. During operation of the fan 58, air (outside air) outside the housing 56 (the copying machine 2) is introduced into the duct 54 from the other opening, and the introduced air is introduced from the opening on the side where the fan 58 is installed. It is discharged as it is. The purpose of providing the duct 54 will be described later.

  FIG. 4A is a perspective view of the duct 54 and members attached to the duct 54. A rectangular frame 60 is joined to the lower outer surface 54 </ b> A of the duct 54. The frame 60 and a part of the lower part of the duct 54 constitute a rectangular box 62 having an opening below. The frame 60 is also made of a material having excellent thermal conductivity, such as aluminum. The box 62 functions as a cooling heat sink that condenses moisture in the air as will be described later.

A plurality of Peltier elements 64A, 64B, 64C, 64D, and 64E, which are thermoelectric conversion elements, are stored in the box 62 (five in this example). In this example, since all the Peltier elements 64A to 64E are the same, the description will be made excluding the alphabetic suffixes “A to E” when it is not necessary to distinguish them.
A perspective view of the Peltier element 64 is shown in FIG. The Peltier element 64 has an overall flat rectangular parallelepiped shape, and when energized from a lead wire (not shown), one main surface 66 cools down to become a cooling surface 66 and the other main surface 68 rises in temperature to heat up the heating surface. 68. Further, when a temperature difference is generated between the two main surfaces 66 and 68, an electromotive force is generated (between the lead wires) by the Seebeck effect. As the Peltier element 64, a known module can be used.

  Each of the Peltier elements 64 </ b> A to 64 </ b> E is attached with its cooling surface 66 in close contact with the lower outer surface 54 </ b> A of the duct 54. In this case, it is preferable that thermal grease or the like is interposed between the cooling surface 66 and the lower outer surface 54A so that the air does not enter. The frame 60 surrounds the side surfaces of the five Peltier elements 64A to 64E so that only the heating surface 68 of the Peltier elements 64A to 64E and the end portion on the heating surface 68 side are exposed (FIG. 2, FIG. 3). In other words, the box 62 surrounds the Peltier elements 64A to 64E so that only the heating surface 68 of the Peltier elements 64A to 64E and the end portion on the heating surface 68 side are exposed. In the present example, the five Peltier elements 64A to 64E are electrically connected in series by wires (not shown). Here, the serial connection body of the Peltier elements 64 to 64E is referred to as a Peltier element unit 128 (FIG. 5B).

  2 and 3, a water guide member 70 is attached to one side surface 60 </ b> A of the box body 62 (frame body 60). The water guide member 70 is formed by bending an elongated wire having a circular cross section into a substantially “L” shape. The water guide member 70 is made of, for example, a metal such as stainless steel or a synthetic resin. In the water guide member 70, the first straight portion 70A is in close contact with and joined to the side surface 60A. As shown in FIG. 2, the first straight portion 70 </ b> A is provided so as to be inclined downward from the horizontal direction. And the 2nd straight part 70B has faced the perpendicular downward direction.

A water guide member 72 similar to the water guide member 70 is also attached to the side surface 60B opposite to the box body 62 (frame body 60) in the same manner.
Further, regions (condensation surfaces) above the water guiding members 70 and 72 on the side surfaces 60A and 60B are covered with a water retention film 74 (not shown in FIG. 3). For the water retention film 74, for example, a water-absorbing polymer can be used. In addition, the thickness of the water retaining film 74 is sufficiently thinner than the radius of the water guiding members 70 and 72.

  A water receiving box 76 is provided below the box 62. The water receiving box 76 has a rectangular parallelepiped shape and is a box that is open at the top. On the side surface in the longitudinal direction of the water receiving box 76, a groove 76A extending in the longitudinal direction is formed. A guide bar 78 attached to the casing (not shown) of the copying machine 2 is fitted in the groove 76A, and the water receiving box 76 is held by the guide bar 78 so as to be slidable in the horizontal direction. A handle 80 is attached to one end surface of the water receiving box 76 in the longitudinal direction. By pulling the handle 80, the water receiving box 76 can be detached from the guide bar 78 and removed from the housing. it can.

Conversely, the water receiving box 76 can be attached to the housing by fitting the guide bar 78 in the groove 76A and pushing the water receiving box 76 into the groove 76A. That is, the water receiving box 76 is detachably attached to the casing (not shown) of the copying machine 2.
FIG. 5A is a diagram illustrating an outline of the main control unit 110.
As shown in the figure, the main control unit 110 has a configuration in which a ROM 114, a RAM 116, and an image memory 118 are connected to the CPU 112 with the CPU 112 as a center. The CPU 112 is connected to each of the CPUs of the image reader unit 4, the printer unit 6, and the operation panel 50 described above.

The ROM 114 stores a control program executed by each CPU.
The RAM 116 stores the number of copies and copy conditions set via the operation panel 50.
As described above, the image memory 118 temporarily stores the image data output from the image reader unit 4.

The CPU 112 comprehensively controls the operation panel 50, the image reader unit 4, and the printer unit 6 to realize a smooth copy operation.
FIG. 5B is a diagram illustrating a part of the configuration of the control unit 120 included in the printer unit 6. The control unit 120 includes a CPU 122 connected to the CPU 112 (FIG. 5A) of the main control unit 110.

The control unit 120 includes a first DC / DC converter 124 and a second DC / DC converter 126.
The first DC / DC converter 124 converts the DC voltage output from the secondary battery 130 into a predetermined voltage and outputs it to the Peltier element unit 128.
The second DC / DC converter 126 converts the DC voltage output from the Peltier element unit 128 into a predetermined voltage and outputs the voltage to the secondary battery 130.

The first DC / DC converter 124 is switched to an ON state or an OFF state by an ON / OFF signal output from the CPU 122. That is, the CPU 122 functions as a control unit that controls the timing of power supply by the secondary battery 130.
The second DC / DC converter 126 is also switched to the ON state or the OFF state by the ON / OFF signal output from the CPU 122.

The control unit 120 also has a fan drive unit 132 and performs ON / OFF control of the fan 58.
Next, the ON / OFF control program for the first DC / DC converter 124, the second DC / DC converter 126, and the fan 58 executed by the CPU 122 will be described with reference to the flowchart shown in FIG. In the flowchart, the first DC / DC converter 124 is expressed as “DC / DC1”, and the second DC / DC converter 126 is expressed as “DC / DC2”.

  When switch 52 (FIG. 1) of copying machine 2 is turned on (YES in step S1), first DC / DC converter 124 is turned on (step S2). When the first DC / DC converter 124 is turned on, energization from the secondary battery 130 to the Peltier element unit 128 (FIG. 5) is started. Thereby, the heating surface 68 of each of the Peltier elements 64A to 64E constituting the Peltier element unit 128 generates heat (in this example, about 100 [° C.]), and assists in raising the temperature of the heating roller 40. Thereby, the warm-up time of the heating roller 40 can be shortened.

Soon after the power is turned on (YES in step S1), the start key is pressed (YES in step S3), and when image formation is started, the first DC / DC until the image formation is completed (YES in step S4). Converter 124 is kept on.
During the fixing operation by the fixing device 38, steam is generated from the heated recording sheet while passing through the fixing nip, and the steam is recovered as follows. That is, relatively high-temperature steam generated from the recording sheet heated at about 180 [° C.] in the fixing nip rises above the fixing nip. The bottom of the box 62 provided above the fixing nip is cooled entirely via the cooling surface 66 of the Peltier elements 64A to 64E (the temperature of the cooling surface 66 is about 20 [° C.], for example). ). And the vapor | steam which has risen contacts the outer side surface (outer peripheral surface of the frame body 60) of the box 62, and is condensed, and it adheres to the said outer side surface as a water droplet. The water droplets are once held by the water retention film 74, but the amount of water droplets due to condensation increases and the water that cannot be held moves downward. And after moving along the groove | channel (inclined slanting right slanting in FIG. 2) between the 1st straight line part 70A of the water conveyance member 70 and the outer peripheral surface of the frame 60, it is slanting right below, and then 2nd straight line part 70B Then, it moves vertically downward, then leaves the lower end of the second linear portion 70B, drops into the water receiving box 76, and is collected. Thereby, it is possible to dehumidify moisture generated from the recording sheet.

Of the steam rising from the fixing nip, the steam that once passes through the vicinity of the outer surface and convects inside the fixing device 38 may be condensed when reaching the outer surface.
When the image forming operation is completed (YES in step S4), the CPU 122 enters the standby mode, so the CPU 122 turns off the first DC / DC converter 124 (step S6) and turns on the second DC / DC converter 126 (step S7). At the same time, the operation of the fan 58 is started (step S8). The CPU 122 also executes steps S6, S7, and S8 even when the CPU 122 enters the standby mode (YES in step S5) because an instruction for image formation is not given for a predetermined time after the power is turned on (step S1). To do.

Thereby, power supply to the Peltier element unit 128 is stopped (step S6), and the Peltier element unit 128 is electrically connected to the secondary battery 130 (step S7). Moreover, outside air will circulate through the duct 54 (step S8).
The surface of the heating roller 40 in the standby mode is maintained at 140 to 150 ° C. as described above. Accordingly, the heating surface 68 of the Peltier elements 64 </ b> A to 64 </ b> E is heated by the heating roller 40 to generate power in the Peltier elements 64 </ b> A to 64 </ b> E, and electricity generated by the power generation is stored in the secondary battery 130.

  In this case, the outside air is circulated through the duct 54 to cool the cooling surface 66 of the Peltier elements 64A to 64E, thereby increasing the temperature difference between the heating surface 68 and the cooling surface 66, thereby reducing the power generation amount. It was decided to increase. Since the heating surface 68 and the cooling surface 66 of the Peltier element 64 are close to each other, when the cooling surface 66 is not actively cooled, the temperature of the Peltier element 64 is entirely increased by the heat from the heating roller 40, A sufficient temperature difference sufficient for power generation cannot be obtained between the heating surface 68 and the cooling surface 66. Therefore, the cooling surface 66 of the Peltier element 64 is cooled by outside air that is sufficiently cooler than the inside of the fixing device 38. In addition, since the electric power required for the operation of the fan 58 to circulate the outside air through the duct 54 is smaller than the electric power obtained from the Peltier element unit 128, there is no problem in the power balance.

The electric power for operating the fan 58 may be obtained from the secondary battery 130 or from an external commercial power source.
When the start key is pressed during the standby mode (YES in step S9) and image formation is started, the second DC / DC converter 126 is operated until the series of image formation is completed (YES in step S13). It is turned off (step S10), the first DC / DC converter 124 is turned on (step S11), and the fan 58 is stopped (step S12). Thus, as described above, the warm-up time after the return instruction from the standby mode is instructed (YES in step S9) can be shortened, and condensation in the apparatus can be prevented as much as possible. The temperature during the fixing operation of the heating roller 40 is about 180 [° C.], and the temperature of the heating surface of the Peltier element 64 is 100 [° C.] lower than this, but the ambient temperature of the heating roller 40 should be increased. This contributes to shortening the warm-up time of the heating roller 40.

When image formation is completed (YES in step S13), steps S6, S7, and S8 are executed, and as described above, power generation by the Peltier element unit 128 and power storage by the secondary battery 130 are performed.
When the switch 52 (FIG. 1) of the copying machine 2 is turned off (YES in step S14), the second DC / DC converter 126 is turned off (step S15) and the operation of the fan 58 is stopped (step S16). The program is terminated.
<Embodiment 2>
In the first embodiment, the Peltier elements 64A, 64B, 64C, 64D, and 64E are electrically connected in series, and power is uniformly supplied to all the Peltier elements 64A to 64E. The amount of power supplied to 64E is individually controlled.

  FIG. 7 is a diagram of the heating roller 40, the pressure roller 42, and the periphery thereof viewed from a direction orthogonal to the longitudinal direction (axial direction) of the heating roller 40 and the pressure roller 42 in the copying machine according to the second embodiment. This is the same as in FIG. In FIG. 7, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment, description thereof is omitted, and different portions will be mainly described below.

  As shown in FIG. 7, the copying machine according to the second embodiment has humidity at positions corresponding to each of the Peltier elements 64A, 64B, 64C, 64D, and 64E in the sheet passing width direction (axial direction of the heating roller 40). Sensors 90A, 90B, 90C, 90D, and 90E are provided. The vertical positions of the humidity sensors 90A to 90E are preferably as close to the fixing nip as possible above the fixing nip. In this example, it is attached to the lower end of the outer surface of the duct 54.

The humidity sensors 90A to 90E can measure the humidity generated by the rising vapor generated from the recording sheet passing through the fixing nip.
For example, when plain paper having a wide width in the paper passing direction passes through the fixing nip, it is considered that each of the humidity sensors 90A to 90E detects substantially the same humidity.
On the other hand, when narrow plain paper passes through the fixing nip, the central humidity sensor 90C is considered to detect higher humidity than the humidity sensors 90A and 90E at both ends.

In addition, when the OHP plastic film passes through the fixing nip, almost no steam is generated, and it is considered that there is almost no change in the humidity detected by the humidity sensors 90A to 90E before and after the passage. In this case, it is considered that there is almost no need for dehumidification.
Therefore, in the present embodiment, the amount of power supplied to the corresponding Peltier elements 90A to 90E is changed according to the magnitude of humidity detected by each of the humidity sensors 90A to 90E. In other words, the Peltier element corresponding to the humidity sensor that detects high humidity increases the power supply amount, and the Peltier element corresponding to the humidity sensor that detects low humidity decreases the power supply amount so as not to consume unnecessary power. ing.

  Therefore, in the present embodiment, as shown in FIG. 8, the control unit 1200 includes a first DC / DC converter 124A to 124E and a second DC / DC converter 126A to 126E for each Peltier element 64A to 64E. did. Further, the CPU 122 outputs an output voltage variable signal to each of the first DC / DC converters 124A to 124E, is output from the secondary battery 130, and is a magnitude of a voltage applied to the Peltier elements 90A to 90E (ie, (Power supply amount) can be changed.

Then, during the fixing operation, the CPU 122 refers to the detection results of the humidity sensors 90A to 90E by the output variable signal, and increases the amount of power supplied to the Peltier element corresponding to the humidity sensor that has detected high humidity.
Since the ON / OFF control of the DC / DC converter etc. other than the above is the same as in the first embodiment, the description thereof is omitted.

As mentioned above, although this invention has been demonstrated based on embodiment, this invention is not restricted to an above-described form, Of course, it can also be set as the following forms, for example.
(1) The power supply to the Peltier element may not be based on the secondary battery. Commercial AC power may be converted into direct current by an AC / DC converter and supplied.
In this case, when the power generation by the Peltier element is not used (when the secondary battery is not provided), the duct 54 is unnecessary.
(2) The water retention film 74 is not necessarily provided. The water droplets adhering to the outer surface of the box 62 due to condensation may be guided to the lower side through the outer surface as they are, and may be guided to the water receiving box 76 by the water guide member 70 as described above.
(4) In the above embodiment, five Peltier elements are used, but the number of Peltier elements can be appropriately changed according to the size of the Peltier element and the size of the fixing device (that is, the number of Peltier elements is Is optional.)

In the above-described embodiment, the plurality of Peltier elements are arranged in one row along the paper width direction (axial direction of the heating roller). However, the number of Peltier elements is not limited to one, and may be two or more. In this case, a plurality of Peltier elements may be arranged in a staggered manner.
In the above embodiment, the intervals between adjacent Peltier elements are arranged close to each other, but a certain gap may be provided.
(5) In the above embodiment, the copying machine has been described as an example. However, the present invention is not limited to the copying machine, and other image forming apparatuses that form an image by an electrophotographic method, such as a facsimile, a printer, or a copying machine. Needless to say, the present invention can also be applied to a multifunction machine having functions of a facsimile and a printer.

  The image forming apparatus according to the present invention can be suitably used for, for example, a copying machine, a facsimile machine, a printer, or a multifunction machine having functions of a copying machine, a facsimile machine, and a printer.

2 Copier 38 Fixing device 40 Heating roller 42 Pressure roller 66 Cooling surface 68 Heating surface 64A, 64B, 64C, 64D, 64E Peltier element 62 Box body 70 Water guide member 76 Water receiving box 122 CPU
124 1st DC / DC converter 130 Secondary battery

Claims (6)

In an image forming apparatus provided with a fixing device that forms a fixing nip by pressing a pressing member on the surface of a heat fixing member, and passes a recording sheet carrying a toner image in the fixing nip to fix it.
A plurality of thermoelectric conversion elements that have a cooling surface that cools when energized and a heating surface that heats up, and are arranged along the sheet passing width direction with the heating surface facing the surface of the heat fixing member When,
Recovery means for recovering water produced by condensation due to the cooling action of the thermoelectric conversion element;
Power supply means for supplying power to the plurality of thermoelectric conversion elements;
Control means for controlling the timing of the power feeding by the power feeding means;
Have
The image forming apparatus, wherein the control unit causes the power supply unit to supply the power during warming up of the heat fixing member and during a fixing operation by the fixing device.   The cooling heat sink is provided in close contact with the cooling surfaces of the plurality of thermoelectric conversion elements, and the cooling heat sink is cooled via the cooling surface, thereby causing the dew condensation on the surface. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 2, wherein a water retaining film is formed on a dew condensation surface of the cooling heat sink. The cooling heat sink is composed of a box surrounding the plurality of thermoelectric conversion elements so that only the heating surface and the heating surface side end portion of the thermoelectric conversion element are exposed,
The recovery means includes
A water receiving box provided below the box;
A water guiding member that is attached to the outer surface of the box and guides water droplets attached to the outer surface due to condensation into the box;
The image forming apparatus according to claim 2, further comprising:   The image forming apparatus according to claim 4, wherein the water receiving box is detachably attached to a housing of the image forming apparatus. A plurality of humidity sensors provided at positions corresponding to each of the thermoelectric conversion elements in the sheet passing width direction;
The plurality of thermoelectric conversion elements are provided above the fixing nip,
The power supply means individually supplies power to each of the thermoelectric conversion elements,
2. The control unit according to claim 1, wherein the control unit further refers to the humidity detected by the humidity sensor, and increases the amount of power supplied to a thermoelectric conversion element corresponding to the humidity sensor that has detected high humidity. Image forming apparatus.

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