JP6188650B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus.

  An electrophotographic image forming apparatus is equipped with a fixing device that fixes toner transferred to a sheet. The fixing device includes a heating roller that is heated to a predetermined fixing temperature, and a pressure roller that can rotate while being pressed against the heating roller. The toner transferred to the sheet is melted and fixed on the sheet when passing through the nip region of the heating roller and the pressure roller.

  By the way, in recent years, it is desired to suppress the number of UFP (Ultra Fine Particle) emission as well as VOC (Volatile Organic Compounds) in the fixing device. For example, it has been found that this UFP is generated by heating a silicon-based material used for a heating roller and a pressure roller of a fixing device. On the other hand, a configuration is known in which UFP generated in the fixing device is removed by electrostatic adsorption (see, for example, Patent Document 1). For example, after UFP is charged to either positive polarity or negative polarity, a configuration in which the UFP is collected using a negative electrode or a positive electrode having a reverse polarity is conceivable.

JP 2010-2803 A

  However, in the configuration in which the UFP is charged to either positive polarity or negative polarity, it is not possible to collect UFP that is difficult to be charged to the polarity.

  An object of the present invention is to provide an image forming apparatus capable of suppressing the number of UFP discharged.

  An image forming apparatus according to an aspect of the present invention includes an exhaust path, a first charging unit, a first collecting unit, a second charging unit, and a second collecting unit. The exhaust path guides air discharged from a fixing device that heats and fixes the toner transferred to the sheet to the outside. The first charging unit is provided in the exhaust path and charges the ultrafine particles in the air to a first polarity. The first collection unit is provided on the downstream side of the first charging unit in the blowing direction of the exhaust path, and is charged to a second polarity opposite to the first polarity. The second charging unit is provided on the downstream side of the first collecting unit in the blowing direction of the exhaust path, and charges the ultrafine particles in the air to the second polarity. The second collection unit is provided on the downstream side of the second charging unit in the blowing direction of the exhaust path, and is charged to the first polarity.

  According to the present invention, the number of UFP discharged from the image forming apparatus can be suppressed.

FIG. 1 is a diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing the configuration of the exhaust mechanism of the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a diagram showing a result of suppressing the emission rate of UFP and VOC in the image forming apparatus according to the embodiment of the present invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings for understanding of the present invention. In addition, the following embodiment is an example which actualized this invention, Comprising: The thing of the character which limits the technical scope of this invention is not.

[Schematic Configuration of Image Forming Apparatus 10]
First, a schematic configuration of the image forming apparatus 10 according to the embodiment of the present invention will be described.

  In FIG. 1, the image forming apparatus 10 is a printer including an image forming unit 3 and a paper feeding unit 4. Note that facsimile machines, copiers, and multifunction machines are also examples of the image forming apparatus according to the present invention.

  The image forming unit 3 is an electrophotographic image forming unit that forms an image on a sheet based on image data input from an information processing apparatus such as a personal computer. Specifically, the image forming unit 3 includes a photosensitive drum 31, a charging device 32, an optical scanning device (LSU) 33, a developing device 34, a transfer roller 35, a cleaning device 36, a fixing device 37, an exhaust mechanism 38, and an exhaust mechanism 38. A paper tray 39 is provided. The sheet is a sheet material such as paper, coated paper, postcard, envelope, and OHP sheet.

  As shown in FIG. 1, the fixing device 37 includes a pair of heating rollers 371 and a pressure roller 372 that are rotatably supported by a casing of the fixing device 37. The fixing device 37 includes a heating unit 373 such as a halogen heater disposed inside the heating roller 371. Note that the pressure roller 372 is indirectly heated by the heating unit 373 via the heating roller 371. The heating unit 373 may be an IH heater that is disposed outside the heating roller 371 and induction-heats the heating roller 371. The heating roller 371 is heated to a predetermined fixing temperature by the heating unit 373. The fixing temperature is, for example, 200 ° C. to 220 ° C.

  The outer surface of the heating roller 371 is covered with a fluorine-based paint such as PFA or PTFE. As a result, the toner on the sheet is fixed to the sheet without adhering to the heating roller 371. In addition, the heating roller 371 is black coated with a metal oxide on the inner peripheral surface with a modified silicon adhesive. Thereby, the heat of the heating unit 373 is efficiently absorbed by the heating roller 371.

  The material of the pressure roller 372 includes elastic members such as elastic silicon rubber. The pressure roller 372 is urged toward the pressure roller 372 by an urging mechanism (not shown), and can be rotated while being in pressure contact with the heating roller 371. As a result, a nip region is formed between the heating roller 371 and the pressure roller 372. In the fixing device 37, when the heating roller 371 is rotationally driven by a driving force of a motor (not shown), the pressure roller 372 pressed against the heating roller 371 is driven to rotate. As a result, the fixing device 37 heats the toner transferred to the sheet and fixes it to the sheet when the sheet passes through the nip region between the heating roller 371 and the pressure roller 372. .

  By the way, the modified silicon used for the black coating of the inner peripheral surface of the heating roller 371 may volatilize a siloxane component that becomes UFP when heated by the heating unit 373 and reaches a predetermined temperature or higher. . In addition, the silicon rubber used as the material of the pressure roller 372 may be heated to volatilize the siloxane component that becomes UFP when the temperature exceeds a predetermined temperature. On the other hand, a configuration is conceivable in which the UFP generated in the fixing device 37 is charged positively or negatively, and collected using an electrode having a polarity opposite to that. However, in the configuration in which the positive polarity or the negative polarity is charged, UFP that is hardly charged to the polarity cannot be collected. On the other hand, in the image forming apparatus 10, the number of UFPs generated is suppressed by the following configuration.

[Exhaust mechanism 38]
Next, the exhaust mechanism 38 will be described with reference to FIG. FIG. 2 is a schematic diagram of a main part showing the configuration of the exhaust mechanism 38 of the image forming apparatus 10.

  The exhaust mechanism 38 can exhaust the air in the vicinity of the fixing device 37 to the outside of the image forming apparatus 10. Specifically, the exhaust mechanism 38 includes an exhaust path 381, a blower fan 382, a first charging unit 383, a first collecting unit 384, a second charging unit 385, a second collecting unit 386, A power source 387, a power source 388, and a filter member 389 are provided.

  The exhaust path 381 is an exhaust duct used to guide the air discharged from the fixing device 8 to the outside of the image forming apparatus 10 and has, for example, a rectangular cross section or a circular cross section. The exhaust path 381 has an intake port 38A provided in the vicinity of the fixing device 37 and an exhaust port 38B for discharging air to the outside of the image forming apparatus 10. For example, the air inlet 38A is provided in the vicinity of one end of the fixing device 37 in the main scanning direction (depth direction in FIG. 2).

  The blower fan 382 blows air sucked from the intake port 38A of the exhaust path 381 toward the exhaust port 38B and discharges the air outside the image forming apparatus 10. Hereinafter, the direction of the air blow by the blower fan 382 is referred to as a blow direction D1.

  The first charging unit 383, the first collecting unit 384, the second charging unit 385, and the second collecting unit 386 are provided in the exhaust path 381, and for example, a wire is formed in a filter shape (a mesh shape or a mesh shape). This is a filter member having a filter surface formed in a lattice shape. The first charging unit 383, the first collection unit 384, the second charging unit 385, and the second collection unit 386 are configured so that the filter surface is perpendicular to the blowing direction D 1 in the exhaust path 381. In this state, it is arranged in the exhaust path 381. The filter surface is, for example, rectangular or circular like the shape of the exhaust path 381. The first charging unit 383, the first collecting unit 384, the second charging unit 385, and the second collecting unit 386 each have a plurality of filter surfaces in the air blowing direction D1 of the exhaust path 381. It may be.

  The first charging unit 383 is connected to the power source 387 and is discharged when a positive DC voltage is applied from the power source 387, and the UFP in the air of the exhaust path 381 is positive ( An example of the first polarity) is charged. The positive DC voltage applied from the power source 387 to the first charging unit 383 is, for example, +2 kV.

  The first collection unit 384 is connected to the power source 388 and is charged to a negative polarity when a negative DC voltage (an example of the second polarity) is applied from the power source 388. The negative DC voltage applied from the power source 388 to the first collector 384 is, for example, −100V.

  On the other hand, the second charging unit 385 is connected to the power source 388 and is discharged when a negative DC voltage is applied from the power source 388, and the UFP in the air of the exhaust path 381 is negatively charged ( An example of the second polarity) is charged. The negative DC voltage applied from the power source 388 to the second charging unit 385 is, for example, −2 kV. That is, the power supply 388 is a power supply device capable of outputting two systems of −100 V and −2 kV. The power source 387 and the power source 388 are controlled by the control unit 5, for example, when an image forming process is executed in the image forming apparatus 10, the first charging unit 383, the first collecting unit 384, A voltage is applied to the second charging unit 385 and the second collection unit 386. A voltage of −2 kV may be applied from the power source 388 to each of the first collection unit 384 and the second charging unit 385. Further, the first charging unit 383 and the second charging unit 385 are not limited to the filter member having the filter surface as long as the UFP can be charged, and may be a discharge wire or a needle electrode. .

  The second collection unit 386 is connected to the power source 387, and is charged to positive polarity when a positive voltage (an example of the first polarity) is applied from the power source 387. The positive DC voltage applied from the power source 387 to the second collection unit 386 is, for example, + 100V. That is, the power supply 387 is a power supply device capable of outputting two systems of +100 V and +2 kV. A voltage of +2 kV may be applied from the power source 388 to each of the first charging unit 383 and the second collection unit 386.

  The filter member 389 is provided in the exhaust port 38B of the exhaust path 381. The filter member 389 collects dust, UFP, VOC, and the like in the air exhausted through the exhaust path 381.

  In the exhaust mechanism 38 configured as described above, the UFP contained in the air discharged through the exhaust path 381 is effectively absorbed by the first collection unit 384 and the second collection unit 386. To be collected.

  Specifically, in the exhaust path 381, UFP is charged to the positive polarity by the first charging unit 383. As a result, the positively charged UFP is collected on the downstream side of the first charging unit 383 by the first collection unit 384 that is negatively charged.

  Further, UFP is charged to the negative polarity by the second charging unit 385 on the downstream side of the first collection unit 384 in the exhaust path 381. As a result, the negatively charged UFP is collected on the downstream side of the second charging unit 385 by the second collecting unit 386 that is positively charged.

  Accordingly, in the exhaust path 381, UFP is effectively collected by the first collection unit 384 and the second collection unit 386 and discharged from the exhaust path 381 to the outside of the image forming apparatus 10. The number of UFPs is suppressed.

  In the present embodiment, the first charging unit 383 and the second collecting unit 386 are charged with positive polarity, and the first collecting unit 384 and the second charging unit 385 are charged with negative polarity. Explained the case. On the other hand, the first charging unit 383 and the second collection unit 386 are negatively charged, and the first collection unit 384 and the second charging unit 385 are positively charged. Is considered.

  By the way, a plurality of collection units each including the first charging unit 383, the first collection unit 384, the second charging unit 385, and the second collection unit 386 are provided in the exhaust path 381. It is also conceivable as another embodiment. Thereby, the number of UFPs discharged from the exhaust mechanism 38 can be further suppressed.

  In particular, when a plurality of collection units are provided, the absolute values of the charging voltages of the first charging unit 383 and the second charging unit 385 are located upstream of the blowing direction D1 in the exhaust path 381. It is possible that the said collection part located in the downstream rather than a collection part is larger. Specifically, the positive charging voltage of the first charging unit 383 of the collection unit on the downstream side in the blowing direction D1 in the exhaust path 381 is the first charging unit 383 of the collection unit on the upstream side. Higher than the positive charging voltage. In addition, the negative charging voltage of the second charging unit 385 of the downstream collecting unit is lower than the negative charging voltage of the second charging unit 385 of the upstream collecting unit. Thereby, the charging performance of UFP in the said collection part of a downstream becomes higher than the said collection part of an upstream.

  Similarly, when a plurality of sets of the collection units are provided, the absolute values of the charging voltages of the first collection unit 383 and the second collection unit 385 are positioned on the upstream side in the blowing direction D1 in the exhaust path 381. It is conceivable that the collecting unit located downstream is larger than the collecting unit. Specifically, the negative charging voltage of the first collecting portion 384 of the collecting portion on the downstream side in the air blowing direction D1 in the exhaust path 381 is the first collecting value of the collecting portion on the upstream side. It is lower than the negative charging voltage of the portion 384. Further, the positive charging voltage of the second collecting unit 386 of the downstream collecting unit is higher than the positive charging voltage of the second collecting unit 386 of the upstream collecting unit. Thereby, the collection force of UFP in the said collection part of a downstream becomes higher than the said collection part of an upstream.

  According to these configurations, there is an increased possibility that the UFP that has not been collected by the upstream collection unit will be collected by the downstream collection unit, and the UFP discharged from the image forming apparatus 10 The number is further suppressed.

  Further, when a plurality of sets of the collection units are provided, the width of the blowing direction in the blowing direction D1 of the first charging unit 383 and the second charging unit 385 is the width of the blowing direction D1 in the exhaust path 381. It is conceivable that the collecting part located on the downstream side is larger than the collecting part located on the upstream side. Specifically, the number of filter surfaces in the blowing direction D1 of the first charging unit 383 of the collecting unit on the downstream side in the blowing direction D1 in the exhaust path 381 is the same as that of the collecting unit on the upstream side. More than the first charging unit 383. In addition, the number of filter surfaces in the blowing direction D1 of the first collection unit 384 of the downstream collection unit is greater than that of the first collection unit 384 of the upstream collection unit. Thereby, the charging performance of UFP in the said collection part of a downstream becomes higher than the said collection part of an upstream.

  Similarly, when a plurality of sets of the collection units are provided, the width of the blowing direction in the blowing direction D1 of the first collecting unit 384 and the second collecting unit 386 is the blowing direction in the exhaust path 381. It is conceivable that the collecting unit located on the downstream side is larger than the collecting unit located on the upstream side of D1. Specifically, the number of filter surfaces in the blowing direction D1 of the first collecting portion 384 of the collecting portion on the downstream side in the blowing direction D1 in the exhaust path 381 is the number of filter surfaces in the upstream on the collecting portion. More than the first collection part 384. In addition, the number of filter surfaces in the blowing direction D1 of the second collection unit 386 of the downstream collection unit is greater than that of the second collection unit 386 of the upstream collection unit. Thereby, the collection force of UFP in the said collection part of a downstream becomes higher than the said collection part of an upstream.

  According to these configurations, there is an increased possibility that the UFP that has not been collected by the upstream collection unit will be collected by the downstream collection unit, and the UFP discharged from the image forming apparatus 10 The number is further suppressed.

  Note that the second charging unit 385 may have a larger absolute value of the charging voltage or a larger width in the blowing direction than the first charging unit 383. Similarly, it is conceivable that the absolute value of the charging voltage is larger or the width in the grand wind direction is larger in the second collecting portion 386 than in the first collecting portion 384.

[Example 1]
Hereinafter, a measurement result of the number of UFP generated in the image forming apparatus 10 will be described.

More specifically, as the measurement condition, the image forming apparatus 10 configured by mounting the exhaust mechanism 38 on a printer “TASKalfa 7550ci” manufactured by Kyocera Document Solutions Inc. is disposed in a stainless steel casing of about 5 m ^3. . Then, continuous printing for 10 minutes was performed after ventilation for 2 hours, and the number of UFPs generated during the 10 minutes was measured by FMPS (Fast Response Mobility Particle Sizer Model 3091) manufactured by TSI Incorporated. In addition, ventilation is performed at a flow rate of 15 m ³ / h by a blower or the like with respect to the internal air of the housing. The blower fan 382 of the blower mechanism 38 is driven so that the intake flow rate to the exhaust path 381 is 10 L / min. Further, a DC voltage of +2 kV is applied from the power source 387 to the first charging unit 383, and a DC voltage of −2 kV is applied from the power source 388 to the second charging unit 385. Further, a DC voltage of +100 V is applied from the power source 387 to the second collector 386, and a DC voltage of −100 V is applied from the power source 388 to the first collector 384. This measurement was performed in accordance with the new certification standard RAL-UZ171 of the environmental label system “Blue Angel” established by the German Federal Environmental Agency. Further, as a comparative example, measurement was also performed for a state where the exhaust mechanism 38 was not attached to the image forming apparatus 10.

  In the FMPS, the particles in the air that are input are charged, and the UFP is based on the value of the current that flows as a result of the particles adhering to an electrode disposed at a predetermined movement distance corresponding to the UFP. The number of occurrences is measured. Note that, as a method for measuring the number of UFPs, a method is used in which the number of particles having a predetermined size or less is counted based on the result of photographing the air discharged from the image forming apparatus 10 with an imaging device. Is also possible.

  In addition to the measurement of the number of UFPs, VOC generated in the image forming apparatus 10 was sampled at 100 ml / min with an adsorption tube containing an activated carbon-based adsorbent. Further, VOC was continuously sampled for 50 minutes after the image forming apparatus 10 was stopped. Then, the sampled adsorption tube was desorbed with a heat desorption apparatus, and the amount of VOC generated was measured with a gas chromatograph mass spectrometer (GCMS). The VOC amount was calculated according to the emission rate calculation formula of the “Blue Angel” environmental label system established by the German Federal Environmental Agency.

  FIG. 3 is a diagram showing the emission rates of UFP and VOC discharged from the image forming apparatus 10. Example 1 shows the case where the exhaust mechanism 38 is mounted, and the comparative example shows the above-mentioned example. The case where the exhaust mechanism 38 is not attached is shown.

  Referring to FIG. 3, the UFP emission rate in the image forming apparatus 10 according to the first embodiment including the discharge mechanism 38 is suppressed as compared with the image forming apparatus 10 according to the comparative example that does not include the discharge mechanism 38. You can see that Referring to FIG. 3, the VOC emission rate in the image forming apparatus 10 of Examples 1 to 8 including the discharge mechanism 38 is also the image forming apparatus of the comparative example not including the discharge mechanism 38. It turns out that it is suppressed compared with 10.

  FIG. 3 shows Examples 2 to 8 which are different from the Example 1 in measurement points in the following points.

[Example 2]
The absolute value of the DC voltage applied to each of the first collection unit 384 and the second collection unit 386 is 500V. In this case, the collection force by the first collection unit 384 and the second collection unit 386 was increased, and the emission rate of UFP was suppressed as compared with Example 1.

[Example 3]
The absolute value of the DC voltage applied to each of the first collection unit 384 and the second collection unit 386 is 1200V. In this case, the collection power by the first collection unit 384 and the second collection unit 386 was increased, and the emission rate of UFP was further suppressed as compared with Example 2.

[Example 4]
The absolute value of the DC voltage applied to each of the first charging unit 383 and the second charging unit 385 is 4 kV. In this case, the charging performance of the UFP by the first charging unit 383 and the second charging unit 385 was enhanced, and the emission rate of UFP was suppressed more than that in Example 1. That is, as shown in the third and fourth embodiments, in order to achieve a high suppression effect on the emission rate of UFP, it is applied to each of the first charging unit 383 and the second charging unit 385. It is conceivable that the absolute value of the direct current voltage is 1200 V or more.

[Example 5]
The collection unit including the first charging unit 383, the first collection unit 384, the second charging unit 385, and the second collection unit 386 is set along the blowing direction D <b> 1 of the exhaust path 381. Two stages are connected. In this case, the UFP charging performance by the first charging unit 383 and the second charging unit 385 was enhanced, and the emission rate of UFP was further suppressed as compared with Example 4.

[Example 6]
The number of filter surfaces of each of the first charging unit 383 and the second charging unit 385 is changed to twice that of the first embodiment. In this case, the charging performance of the UFP by the first charging unit 383 and the second charging unit 385 was enhanced, and the emission rate of UFP was suppressed more than that in Example 1.

[Example 7]
The number of filter surfaces included in each of the first collection unit 384 and the second collection unit 386 is changed to twice that of the first embodiment. In this case, the collection force by the first collection unit 384 and the second collection unit 386 was increased, and the emission rate of UFP was suppressed as compared with Example 1.

[Example 8]
The number of filter surfaces included in each of the first charging unit 383 and the second charging unit 385 is doubled as compared with the first embodiment, and the first collecting unit 384 and the second collecting unit. The number of filter surfaces each 386 has is changed to twice that of the first embodiment. In this case, the charging performance of the UFP by the first charging unit 383 and the second charging unit 385 is enhanced, and the collecting power by the first collecting unit 384 and the second collecting unit 386 is increased, and the embodiment described above. The emission rate of UFP was further suppressed as compared with 7 and Example 8.

3: Image forming unit 4: Paper feeding unit 5: Control unit 10: Image forming device 37: Fixing device 371: Heating roller 372: Pressure roller 373: Heating unit 38: Exhaust mechanism 38A: Intake port 38B: Exhaust port 381: Exhaust path 382: blower fan 383: first charging unit 384: first collecting unit 385: second charging unit 386: second collecting unit 387: power source 388: power source 389: filter member

Claims (11)

An exhaust path for guiding the air discharged from the fixing device that heats and fixes the toner transferred to the sheet to the outside;
A first charging unit provided in the exhaust path for charging the ultrafine particles in the air to a first polarity;
A first collection unit that is provided downstream of the first charging unit in the blowing direction of the exhaust path and is charged to a second polarity opposite to the first polarity;
A second charging unit provided on the downstream side of the first collection unit in the blowing direction of the exhaust path and charging the ultrafine particles in the air to the second polarity;
A second collection unit that is provided downstream of the second charging unit in the blowing direction of the exhaust path and is charged to the first polarity;
An image forming apparatus comprising:   2. The image forming apparatus according to claim 1, wherein the first collection unit and the second collection unit are filter members having a filter surface that is arranged perpendicular to a blowing direction of the exhaust path.   3. The image forming apparatus according to claim 1, wherein the first charging unit and the second charging unit are filter members having a filter surface that is arranged perpendicular to a blowing direction of the exhaust path.   The exhaust path is provided with a plurality of sets of collecting units each including the first charging unit, the first collecting unit, the second charging unit, and the second collecting unit. The image forming apparatus according to claim 3.   In the plurality of sets of the collecting units, the absolute values of the charging voltages of the first charging unit and the second charging unit are the downstream of the collecting unit on the upstream side in the blowing direction of the exhaust path. The image forming apparatus according to claim 4, wherein the portion is larger.   In the plurality of collection units, the absolute value of the charging voltage of the first collection unit and the second collection unit is lower than the collection unit on the upstream side in the blowing direction of the exhaust path. The image forming apparatus according to claim 4, wherein the collecting unit is larger.   In the plurality of sets of the collecting units, the width of the first charging unit and the second charging unit in the air blowing direction is lower than the collecting unit on the upstream side in the air blowing direction of the exhaust path. The image forming apparatus according to claim 4, wherein a portion is larger.   In the plurality of sets of the collecting units, the width of the first collecting unit and the second collecting unit in the blowing direction is lower than the collecting unit on the upstream side in the blowing direction of the exhaust path. The image forming apparatus according to claim 4, wherein the collection unit is larger.   The image forming apparatus according to claim 1, wherein an absolute value of a DC voltage applied to each of the first charging unit and the second charging unit is 1200 V or more.   The image forming apparatus according to claim 1, wherein the fixing device includes a pair of rollers arranged in pressure contact with a heating unit that heats one or both of the rollers. The image forming apparatus according to claim 10, wherein the roller includes silicon rubber.

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