JP2017040748A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can effectively cool a sheet after fixation of a toner image and collect ultra fine particles included in an exhaust air after the cooling.SOLUTION: An image forming apparatus comprises: an exhaust port 41 that is provided in a housing for exhausting an air in the vicinity of a conveyance path of a sheet P after fixation of a toner image; a filter 43 and an exhaust fan 42 that are arranged in the exhaust port 41; a suction port 40 that is provided on a surface of the housing on the opposite side of the exhaust port 41 across the conveyance path; and a suction fan 44 that is arranged in the suction port 40. An air sucked from the outside by the suction fan 44 flows in a direction parallel to a surface of the sheet P passing through the conveyance path and perpendicular to a sheet conveyance direction, and is exhausted to the outside by the exhaust fan 42 through the filter.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an electrophotographic image forming apparatus, and more particularly, to an improvement for effectively cooling a sheet after fixing a toner image and collecting ultrafine particles contained in exhaust after cooling.

  In recent years, regulations on ultra fine particles (UFP) contained in exhaust from image forming apparatuses have become stricter. For this reason, the image forming apparatus is required to discharge the air after the ultrafine particles in the exhaust gas are collected and cleaned using a filter or the like to the atmosphere. As a method of reducing the ultra fine particles contained in the exhaust from the image forming apparatus and cooling the paper after fixing the toner image, air is blown onto the paper and the fine particles generated from the fixing device or the paper together with the air or volatile organic matter. There is a technique in which a compound (VOC) gas is sucked and collected by a filter.

  For example, in FIG. 1 of Patent Document 1, the paper is cooled by the air sucked by the fan 10 and the air blown to the paper by the fan 13, and the VOC gas is passed through the catalytic air filter 11 and the adsorption air filter 12. Has been disclosed.

JP 2006-349826 A

  In the image forming apparatus described in Patent Document 1, wind is blown on the surface of the sheet along the sheet conveyance direction. As can be seen from FIG. 2 of Patent Document 1, the suction of UFP at the end in the sheet conveyance direction is sufficiently performed. I can't do it. As can be seen from FIG. 4 of Patent Document 1, when air is blown in the vertical direction with respect to the paper passing through the conveyance path, the amount of air sucked from the back surface of the paper to the filter side is reduced, and the UFP is filtered. Cannot be sufficiently collected, and as a result, the amount of UFP discharged from the image forming apparatus increases. Furthermore, although the wind hits the surface (toner surface) of the paper, UFP generated from the toner of the paper after passing through the fixing roller cannot be sucked.

  The present invention solves the above-described conventional problems and provides an image forming apparatus capable of effectively cooling the paper after fixing the toner image and collecting the ultrafine particles contained in the exhaust after cooling. The purpose is to do.

  The image forming apparatus according to claim 1, wherein an exhaust port provided in a housing for exhausting air in the vicinity of a paper conveyance path after fixing a toner image, a filter disposed in the exhaust port, and an exhaust fan Air sucked from the outside by the intake fan, and an intake port provided on a surface of the casing opposite to the exhaust port across the conveyance path, and an intake fan disposed in the intake port Flows in a direction parallel to the surface of the sheet passing through the conveyance path and perpendicular to the sheet conveyance direction, and then discharged to the outside through the filter by the exhaust fan.

  The image forming apparatus according to claim 2 is the image forming apparatus according to claim 1, wherein the air sucked from the outside by the intake fan flows along both front and back surfaces of the sheet passing through the conveyance path. An exhaust port, the exhaust fan, the intake port, and the intake fan are arranged.

  The image forming apparatus according to claim 3 is disposed in a first air port provided in a housing for exhausting air in the vicinity of a paper conveyance path after fixing a toner image, and the first air port. A filter and an electric fan; and a second air port provided on a surface of the casing opposite to the first air port across the conveyance path, and an exhaust fan is provided outside the second air port An exhaust cleaning unit that can be mounted, and further includes a sensor that detects mounting of the exhaust cleaning unit, and a control unit that reverses the blowing direction of the electric fan based on a detection signal of the sensor, When the cleaning unit is not installed, the control unit causes the electric fan to function as an exhaust fan, and when the exhaust cleaning unit is installed, the control unit causes the electric fan to function as an intake fan. The air sucked from the outside by the electric fan flows in a direction parallel to the surface of the sheet passing through the conveyance path and perpendicular to the sheet conveyance direction, and then discharged to the outside through the exhaust purification unit. To do.

  The image forming apparatus according to claim 4 is the image forming apparatus according to claim 3, wherein the filter is detachable from the first air port and is also detachable from the second air port. When the exhaust purification unit is not attached, the filter is attached to the first air port, and when the exhaust purification unit is attached, the filter is attached to the second air port. It is possible to replace with.

  The image forming apparatus according to claim 5 is the image forming apparatus according to claim 3 or 4, wherein the control unit reverses the blowing direction by changing the direction of the case of the electric fan. And

  The image forming apparatus according to claim 6 is the image forming apparatus according to claim 3 or 4, wherein the control unit reverses the blowing direction by changing the rotation direction of the blades of the electric fan. Features.

  The image forming apparatus according to claim 7, wherein an exhaust port provided in a housing for exhausting air in the vicinity of a sheet conveyance path after fixing a toner image, a filter disposed in the exhaust port, and an electric fan And an intake port provided on the surface of the casing opposite to the exhaust port across the transport path, and an exhaust purification unit incorporating an exhaust fan can be mounted outside the exhaust port. The electric fan is attachable / detachable to / from the exhaust port, and when the exhaust purification unit is mounted, the electric fan is replaced with the intake port. It is possible to function as an intake fan.

  An image forming apparatus according to an eighth aspect is the image forming apparatus according to the third or seventh aspect, wherein a sensor that detects attachment of the exhaust purification unit and a flow rate of the electric fan based on a detection signal of the sensor. And a control unit for adjustment.

  The image forming apparatus according to claim 9 is the image forming apparatus according to claim 8, wherein when the exhaust cleaning unit is mounted, the control unit is compared with that before the exhaust cleaning unit is mounted. The air volume of the electric fan is increased.

  An image forming apparatus according to a tenth aspect is the image forming apparatus according to the eighth aspect, wherein when the exhaust cleaning unit is mounted, the control unit is compared with a state before the exhaust cleaning unit is mounted. The air volume of the electric fan is reduced.

  An image forming apparatus according to an eleventh aspect is the image forming apparatus according to the third or seventh aspect, wherein a sensor for detecting attachment of the exhaust cleaning unit and a fixing temperature of the fixing device are controlled to be a target temperature. And a control unit, wherein the control unit sets the target temperature higher when the exhaust purification unit is installed than when the exhaust purification unit is installed.

  An image forming apparatus according to a twelfth aspect of the present invention is the image forming apparatus according to the third or seventh aspect, further comprising a sensor that detects attachment of the exhaust cleaning unit, and a control unit that variably controls the sheet conveyance speed. When the exhaust cleaning unit is mounted, the control unit sets the paper transport speed higher than before the exhaust cleaning unit is mounted.

  The image forming apparatus according to claim 13 is the image forming apparatus according to claim 3 or 7, wherein a sensor that detects attachment of the exhaust cleaning unit and an attribute of a sheet that can be used based on a detection signal of the sensor. And a controller for releasing the restriction.

  According to the image forming apparatus of the first aspect, the exhaust fan and the intake air are connected to the exhaust port and the intake port provided on the opposite surfaces (for example, the back surface and the front surface) of the housing with the paper conveyance path after the toner image is fixed. A fan is arranged, and air sucked from the outside by the intake fan flows in a direction parallel to the surface of the paper passing through the conveyance path and perpendicular to the paper conveyance direction, and then exhausted through the filter by the exhaust fan. Therefore, it is possible to effectively cool the paper after fixing the toner image and collect the ultra fine particles contained in the exhaust after cooling. In particular, since the cooling air can flow through the entire sheet including the end in the paper transport direction without causing the paper to become a wall for the flow of the cooling air, it is disposed at the exhaust port without scattering ultrafine particles. Can be collected with a filter. Therefore, efficient collection of ultrafine particles and cooling of the paper can be achieved in a balanced manner.

  According to the image forming apparatus of claim 2, the exhaust port, the exhaust fan, the intake port, and the intake air so that the air sucked from outside by the intake fan flows along both the front and back surfaces of the sheet passing through the conveyance path. Since the fan is disposed (substantially in a straight line with the paper passing through the conveyance path), it is possible to achieve both the efficient collection of ultrafine particles and the cooling of the paper in a balanced manner.

  According to the image forming apparatus of the third aspect, the first air port (exhaust port) and the first air port provided on the opposing surfaces (for example, the back surface and the front surface) of the housing sandwiching the sheet conveyance path after the toner image is fixed. Even in the case of an image forming apparatus in which an electric fan (exhaust fan) is arranged at the first air port and the electric fan is not arranged at the second air port among the two air ports (intake ports), If an exhaust purification unit with a built-in exhaust fan is installed outside the air port, the air blowing direction of the electric fan at the first air port is reversed and functions as an intake fan. Can be realized and the effect can be achieved.

  According to the image forming apparatus of the fourth aspect, when the exhaust cleaning unit is mounted outside the second air port as described above, the filter mounted on the first air port is used as the second air port. By replacing the exhaust gas from the image forming apparatus, after passing through the filter, the exhaust gas further passes through the filter built in the exhaust gas cleaning unit, so that the collection rate of ultra fine particles in the exhaust gas is exhausted. Can be improved.

  In the image forming apparatus according to claim 5, the direction of the case of the electric fan is changed, and in the image forming apparatus according to claim 6, the rotation direction of the blades of the electric fan is changed to change the first air port. The blowing direction of the electric fan can be changed, and the above-described effects can be achieved.

  According to the image forming apparatus of claim 7, the exhaust port is one of the exhaust ports and the intake ports provided on the opposing surfaces (for example, the back surface and the front surface) of the housing across the conveyance path of the sheet after fixing the toner image. Even in the case of an image forming apparatus in which an electric fan (exhaust fan) is disposed in the intake port and no electric fan (intake fan) is disposed in the intake port, exhaust cleaning is performed by incorporating an exhaust fan outside the exhaust port. By mounting the unit and replacing the electric fan at the exhaust port with the intake port so as to function as the intake fan, the same configuration as that of the first aspect can be realized and the effect can be achieved.

  According to the image forming apparatus of the eighth aspect of the present invention, since the image forming apparatus further includes a sensor that detects attachment of the exhaust cleaning unit and a control unit that adjusts the air volume of the electric fan based on the detection signal of the sensor, It is possible to increase the cooling efficiency or the collection efficiency of ultrafine particles. Specifically, it is as follows.

  In the image forming apparatus according to claim 9, when the exhaust cleaning unit is mounted, the air flow rate of the electric fan is increased compared to before the exhaust cleaning unit is mounted, so that the cooling efficiency of the sheet can be increased. It becomes possible. In the image forming apparatus according to claim 10, when the exhaust purification unit is attached, the air volume of the electric fan is made smaller than before the exhaust purification unit is attached, so that the collection efficiency of ultrafine particles is increased. It becomes possible.

  According to the image forming apparatus of the eleventh aspect, when the exhaust cleaning unit is mounted, the target temperature of the fixing temperature is set higher than before the exhaust cleaning unit is mounted. According to this image forming apparatus, since the paper conveyance speed is set high, it is possible to improve the printing speed (productivity) in combination with the improvement of the cooling efficiency by increasing the air volume of the electric fan.

  According to the image forming apparatus of the thirteenth aspect, when the exhaust cleaning unit is mounted, the restriction on the attributes (thickness, etc.) of the usable paper is released. Thicker (higher heat capacity) paper can be used.

1 is a schematic configuration diagram illustrating an internal configuration of a printer unit of an image forming apparatus according to an embodiment of the present invention. 1 is a perspective view showing an external appearance of an image forming apparatus. FIG. 6 is a schematic plan view illustrating a flow of cooling air inside the printer unit. It is a side surface schematic diagram which shows the flow of the cooling air inside a printer part. It is a plane schematic diagram of the printer part which shows the flow of the cooling air in the 1st modification of this embodiment. It is a side surface schematic diagram of the printer part which shows the flow of the cooling air in the 1st modification of this embodiment. It is a block diagram which shows the part relevant to the control by this invention among a control part and its surrounding electronic circuit. It is a flowchart which shows the example of control in which a control part reverses the ventilation direction of an electric fan. It is a plane schematic diagram of the printer part which shows the flow of the cooling air in the 2nd modification of this embodiment. It is a side surface schematic diagram of the printer part which shows the flow of the cooling air in the 2nd modification of this embodiment. It is a flowchart which shows the example of control in which a control part adjusts the air volume of an electric fan in a 1st modification and a 2nd modification.

  Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. First, FIG. 1 shows an internal configuration of the printer unit of the image forming apparatus according to the embodiment. The printer unit 1 of this image forming apparatus is a tandem color digital printer, and FIG. 1 shows an outline of the internal configuration of the printer unit 1 when the image forming apparatus is viewed from the front.

  The printer unit 1 includes an image processing device 3, a paper feeding device 4, a fixing device 5, and the like in the housing 2. Although details are not illustrated, the printer unit 1 is configured to execute a print job based on the print command when receiving a print command from an external terminal or the like via a network connection, for example.

  The paper feeding device 4 located at the lower part in the housing 2 includes a paper feeding cassette 21 that accommodates the recording material P, a pickup roller 22 that feeds the recording material P in the paper feeding cassette 21 from the uppermost layer, and a fed recording material P. A pair of separation rollers 23 for separating the recording materials one by one, a pair of timing rollers 24 for conveying the recording material P separated into one sheet to the image processing apparatus 3 at a predetermined timing, and the like. The recording material P in each paper feed cassette 21 is sent out one by one from the top layer to the paper transport path 30 by the rotation of the pickup roller 22 and the separation roller 23. The sheet conveyance path 30 passes from the sheet feeding cassette 21 of the sheet feeding device 4 through the nip portion of the timing roller pair 24, the secondary transfer nip portion of the image processing device 3, and the fixing nip portion 33 of the fixing device 5. 2 to the discharge roller pair 26 at the top.

  The image processing device 3 positioned above the paper feeding device 4 plays a role of transferring a toner image formed on a photosensitive drum 13 which is an example of an image carrier to a recording material P, and is an intermediate transfer member. And a total of four image forming sections 7 corresponding to the respective colors of yellow (Y), magenta (M), cyan (C) and black (K).

  The intermediate transfer belt 6 is an endless belt made of a conductive material, and is wound around a driving roller 8 located on the right side of the central part in the housing 2 and a driven roller 9 located on the left side of the central part. ing. A secondary transfer roller 10 is disposed outside the portion of the intermediate transfer belt 6 that is wound around the drive roller 8. The intermediate transfer belt 6 rotates in the counterclockwise direction in FIG. 1 by rotating the driving roller 8 in the counterclockwise direction in FIG. 1 by the power transmission of the main motor.

  The secondary transfer roller 10 is in contact with the intermediate transfer belt 6, and a portion between the intermediate transfer belt 6 and the secondary transfer roller 10 (contact portion) is a secondary transfer nip portion as a secondary transfer region. . The secondary transfer roller 10 rotates in the clockwise direction in FIG. 1 with the rotation of the intermediate transfer belt 6 or with the movement of the recording material P that is nipped and conveyed by the secondary transfer nip portion. A transfer belt cleaner 12 for removing untransferred toner on the intermediate transfer belt 6 is disposed on the outer peripheral side of the portion of the intermediate transfer belt 6 wound around the driven roller 9. The transfer belt cleaner 12 is in contact with the intermediate transfer belt 6.

  The four image forming units 7 are arranged along the intermediate transfer belt 6 in the order of yellow (Y), magenta (M), cyan (C), and black (K) from the left in FIG. They are arranged side by side. In FIG. 1, for convenience of explanation, symbols Y, M, C, and K are attached to each image forming unit 7 according to the reproduction color. Each image forming unit 7 includes a photosensitive drum 13 as an example of an image carrier that rotates clockwise in FIG. Around the photosensitive drum 13, a charging device 14, an exposure device 19, a developing device 15, a primary transfer roller 16, and a photosensitive cleaner 17 are arranged in this order along the clockwise rotation direction in FIG. 1.

  The photosensitive drum 13 is negatively charged and is configured to rotate clockwise in FIG. 1 by power transmission from the main motor. The charging device 14 uniformly charges the surface of the photosensitive drum. The developing device 15 makes the electrostatic latent image formed on the photosensitive drum 13 visible by reversal development using toner having a negative polarity.

  The primary transfer roller 16 is located on the inner peripheral side of the intermediate transfer belt 6 and faces the photosensitive drum 13 of the corresponding image forming unit 7 with the intermediate transfer belt 6 interposed therebetween. The primary transfer roller 16 also rotates counterclockwise in FIG. 1 as the intermediate transfer belt 6 rotates. Between the intermediate transfer belt 6 and the primary transfer roller 16 (contact portion) is a primary transfer nip portion as a primary transfer region. The photoreceptor cleaner 17 is for removing untransferred toner remaining on the photoreceptor drum 13, and is in contact with the photoreceptor drum 13. An exposure device 19 is disposed below each image forming unit 7. The exposure device 19 forms an electrostatic latent image on each photosensitive drum 13 by laser light based on image information from an external terminal or the like.

  Each image forming unit 7 is a cartridge (integrated structure) in which the photosensitive drum 13, the charging device 14, the exposure device 19, the developing device 15, and the photosensitive cleaner 17 are collectively accommodated in the housing 20. A so-called process cartridge is detachably attached to the housing 2. A hopper (not shown) that accommodates toner to be supplied to each developing device 15 is disposed above the intermediate transfer belt 6.

  In each image forming unit 7, when a laser beam corresponding to an image signal is projected from the exposure device 19 onto the photosensitive drum 13 charged by the charging device 14, an electrostatic latent image is formed. The electrostatic latent image is reversely developed with toner supplied from the developing device 15 and becomes a toner image of each color. The toner images on the respective photosensitive drums 13 are primarily transferred from the photosensitive drum 13 to the outer peripheral surface of the intermediate transfer belt 6 in the order of yellow, magenta, cyan, and black at the corresponding primary transfer nip portions, and are superimposed. . Untransferred toner remaining on the photosensitive drum 13 is scraped off by the photosensitive cleaner 17 and removed from the photosensitive drum 13. When the recording material P passes through the secondary transfer nip portion, the superimposed four color toner images are secondarily transferred onto the recording material P all at once. Untransferred toner remaining on the intermediate transfer belt 6 is scraped off by the transfer belt cleaner 12 and removed from the intermediate transfer belt 6.

  The fixing device 5 positioned above the secondary transfer roller 10 includes a fixing roller 31 having a built-in fixing heater such as a halogen lamp, and a pressure roller 32 in pressure contact with the fixing roller 31. A contact portion between the fixing roller 31 and the pressure roller 32 is a fixing nip portion which is a fixing region. The recording material P on which the unfixed toner image has been transferred through the secondary transfer nip portion is heated and pressurized when passing through the fixing nip portion between the fixing roller 31 and the pressure roller 32, and is not fixed. The toner image is fixed on the recording material P. Thereafter, the recording material P is discharged onto the paper discharge tray 27 by the rotation of the discharge roller pair 26.

  A control unit 28 that controls the overall image forming apparatus is disposed between the image processing apparatus 3 and the sheet feeding apparatus 4 inside the housing 2. The control unit 28 is mounted with a microprocessor, memory, I / O, various drive circuits, and the like that execute various arithmetic processes, storage, and control.

  FIG. 2 is a perspective view illustrating an appearance of the image forming apparatus according to the present embodiment including the printer unit 1 as described above. This image forming apparatus is a so-called multifunction machine, and has a plurality of functions such as a copy function, a scanner function, a printer function, and a fax function. A document reading unit 102 having an automatic document feeder (ADF) 101 is provided on the printer unit 1 (the housing 2 thereof). An operation panel 103 including a liquid crystal display is provided on the front right side.

  The document reading unit 102 and the printer unit 1 are connected on the right side, and a paper discharge tray 27 is provided on the left side (a space below the document reading unit 102). Accordingly, the sheet discharge port having the discharge roller pair 26 in FIG. 1 is provided at the right end of the space below the document reading unit 102. In addition, an intake port 40 is formed in the upper front portion of the printer unit 1 (below the operation panel 103). An exhaust port 41 (see FIGS. 3 and 4) is formed at a position corresponding to the intake port 40 on the back surface of the printer unit 1.

  3 is a schematic plan view showing the flow of cooling air inside the printer unit 1, and FIG. 4 is a schematic side view showing the flow of cooling air inside the printer unit 1. As shown in FIG. Each of the air sucked from the air inlet 40 cools the paper (recording material) P after fixing the toner image and is discharged from the air outlet 41 by an arrow line. In FIG. 3, the conveyance direction of the paper P is indicated by a white arrow, and in FIG. 4, the cross section (front end) of the paper P is drawn with emphasis on the thickness. In the internal structure of the printer unit 1 shown in FIG. 1, the paper P after the toner image is fixed, that is, the paper P that has passed through the fixing device 5 from the bottom to the top is bent in the horizontal direction along the conveyance path and discharged. It is conveyed toward the roller pair 26.

  An exhaust fan 42 and a filter 43 are installed inside the exhaust port 41 so that air near the conveyance path of the paper P after toner image fixing is cleaned by the filter 43 and exhausted. The vicinity of the conveyance path of the paper P after the toner image is fixed corresponds to the vicinity of a region RG indicated by a broken line in FIG. Further, an intake fan 44 is provided inside the intake port 40, and air sucked from the outside by the intake fan 44 is blown onto the sheet P passing through the sheet conveyance path.

  The air sucked in by the intake fan 44 flows in a direction parallel to the surface of the sheet P passing through the sheet conveyance path and perpendicular to the sheet conveyance direction, passes through the filter 43 by the exhaust fan 42, and is discharged from the exhaust port 41. The As shown in FIGS. 3 and 4, the air intake 40, the air intake fan 44, the filter 43, the exhaust fan 42, and the air exhaust 41 are arranged in a substantially straight line, and the air sucked in by the air intake fan 44 Flows along both the front and back sides of the paper P passing through.

  With the above configuration, the paper P after the toner image fixing is effectively cooled, and ultra fine particles (UFP) generated from the paper P are efficiently collected by the filter 43, and the cleaned air is discharged. Discharged. For example, in a conventional small-sized image forming apparatus, an exhaust fan is disposed at the exhaust port, but no intake fan is disposed at the intake port. In this case, the air flow is slow at a place away from the exhaust fan, and the cooling efficiency of the paper P is low when high-speed printing is performed. If the rotational speed of the exhaust fan is increased to increase the air volume (wind speed is increased), the noise increases and the problem that ultra fine particles (UFP) pass through the filter 43 may also occur.

  On the contrary, a configuration in which an intake fan is disposed at the intake port and an exhaust fan is not disposed at the exhaust port is conceivable as a configuration that requires only one electric fan, but in this case, ultrafine particles (UFP) generated from the paper P are considered. Diffuses and is not efficiently collected by the filter disposed at the exhaust port, and air containing ultrafine particles easily leaks from the image forming apparatus to the outside. Regarding the cooling efficiency of the paper P, even if a high cooling effect is obtained in the vicinity of the intake fan, there is a high possibility that the paper P is not sufficiently cooled in the vicinity of the exhaust port.

  In the image forming apparatus of the present embodiment, air sucked by the intake fan 44 from the intake port 40 flows along both sides of the paper P, is collected by the exhaust fan 42 on the filter 43, passes through the filter 43, and then passes through the exhaust port 41. Since the toner is discharged, it is possible to achieve both a high cooling effect of the paper P after fixing the toner image and a high collection efficiency of ultra fine particles by the filter.

  Note that, in the present embodiment, the printer unit 1 (image forming apparatus) in which the intake port 40 is provided on the front surface and the exhaust port 41 is provided on the back surface is illustrated, but the present invention is not limited thereto. . For example, the present invention can be applied to an image forming apparatus in which an intake port is provided on the back surface and an exhaust port is provided on the front surface. In that case, it goes without saying that the arrangement of the intake fan, filter, and exhaust fan is also changed. The present invention can also be applied to an image forming apparatus in which an intake port is provided on one of the left and right side surfaces and an exhaust port is provided on the other side surface. However, in this case, the paper conveyance path inside the printer unit, the paper feed direction, the paper discharge direction, and the like are also changed. The above-mentioned diversity regarding the facing surface of the image forming apparatus provided with the air inlet and the air outlet is the same in the following modifications.

  Next, a first modification of the image forming apparatus of the present embodiment is shown in FIGS. FIG. 5 is a schematic side view illustrating the flow of cooling air inside the printer unit 1 before the exhaust purification unit 50 is mounted in the first modification. FIG. 6 is a schematic side view showing the flow of cooling air inside the printer unit 1 after the exhaust cleaning unit 50 is mounted. In the image forming apparatus according to the first modification, only the exhaust fan is originally arranged in the printer unit 1 and no intake fan is provided. However, the exhaust gas cleaning unit 50 which is an optional device is attached and the exhaust of the printer unit 1 is performed. By reversing the fan blowing direction to function as an intake fan, the same configuration and effects as in the above-described embodiment are realized.

  As shown in FIG. 5, an exhaust port (first air port) 51 is formed on the front surface of the printer unit 1 (housing 2), and a filter 52 and an exhaust fan (electric fan) 53 are arranged inside the exhaust port (first air port). An intake port (second air port) 54 is formed at a position facing the exhaust port 51 on the back surface of the printer unit 1 (housing 2). Even in this state, the intake port 54, the exhaust fan 53, the filter 52, and the exhaust port 51 are arranged substantially in a straight line across the conveyance path of the sheet P after the toner image is fixed. The sheet P flows in a direction parallel to both the front and back surfaces of the sheet P and perpendicular to the sheet conveyance direction, passes through the filter 52 by the exhaust fan 53, and is discharged from the exhaust port 51. However, since the intake fan is not disposed at the intake port, as described above, the air flow is slow at a place away from the exhaust fan 53, and the cooling efficiency of the paper P becomes low when printing at high speed. is there.

  As shown in FIG. 6, in the image forming apparatus of the first modified example, an exhaust purification unit 50 including an exhaust fan 55 can be mounted outside the second air port 54. In the exhaust purification unit 50, an intake port 56 and an exhaust port 57 are formed on opposing surfaces of a rectangular parallelepiped case (duct), and a filter 58 and an exhaust fan 55 are connected in series between the intake port 56 and the exhaust port 57. It has an arranged configuration. Exhaust air from the image forming apparatus (printer unit 1) is sucked from the intake port 56 by the exhaust fan 55, and discharged from the exhaust port 57 through the filter 58. Thereby, it has a function of collecting the fine particles contained in the exhaust gas by the filter 58 and discharging the purified air.

  In addition, a mounting sensor S <b> 1 that detects whether or not the exhaust purification unit 50 is mounted is provided in the casing 2 of the printer unit 1, and a detection signal thereof is input to the control unit 28. The wearing sensor S1 can be configured by a limit switch or a photo sensor. In addition, the electric fan 53 disposed inside the first air port 51 on the front surface of the printer unit 1 is configured to be able to rotate 180 degrees around the central axis Z1 in the vertical direction by the actuator A1. Thereby, it is possible to reverse the blowing direction of the electric fan 53 originally used as an exhaust fan and use it as an intake fan.

  FIG. 7 is a block diagram showing portions related to the control according to the present invention in the control unit 28 and its surrounding electronic circuits. The control unit 28 includes a microprocessor, a program storage ROM, a data storage RAM, an input / output circuit (I / O), and the like. The detection signal of the mounting sensor S1 described above is input to the control unit 28. Based on the detection signal, the control unit 28 directs the case of the electric fan 53 via the actuator A1 when the exhaust purification unit 50 is mounted. Invert (air blowing direction) to function as an intake fan.

  In addition, a detection signal of the temperature sensor T1 that detects the surface temperature of the fixing roller 31 is input to the control unit 28, and based on the detected temperature, the control unit 28 sets the surface temperature of the fixing roller 31 to the target temperature. Feedback control (temperature adjustment control) of the fixing heater H1 is performed. Further, as will be described later, the control unit 28 can perform variable control of the sheet conveyance speed via the sheet conveyance mechanism M1. Further, the control unit 28 outputs display data and key input signals to the operation panel 103.

  FIG. 8 is a flowchart illustrating an example of control in which the control unit 28 reverses the blowing direction of the electric fan 53 via the actuator A1. In step # 101, the control unit 28 checks whether or not the exhaust purification unit (CU) 50 is mounted based on the detection signal of the mounting sensor S1. If the exhaust purification unit 50 is not attached, the control unit 28 sets the direction of the electric fan 53 in the exhaust direction via the actuator A1 in step # 102 (FIG. 5), and the exhaust purification unit 50 is attached. If so, the control unit 28 sets the direction of the electric fan 53 to the intake direction via the actuator A1 in step # 103 (FIG. 6).

  As described above, in the first modified example, the electric fan 53 that is an exhaust fan is disposed in the exhaust port (first air port) 51, and no electric fan is disposed in the intake port (second air port) 54. Even in the image forming apparatus, by mounting the exhaust cleaning unit 50 including the exhaust fan 55 on the outside of the second air port 54, the blowing direction of the electric fan 53 is reversed and functions as an intake fan. The same configuration and effect as the embodiment shown in FIGS. 3 and 4 can be obtained.

  In the first modification, the air blowing direction is reversed by reversing the direction (of the case) of the electric fan 53, but an electric fan whose blades are rotatable in both forward and reverse directions is used, and the rotation direction thereof. You may comprise so that a ventilation direction may be reversed by reversing. In this case, in step # 102 and step # 103 of FIG. 8, the control unit 28 changes the direction of rotation of the blades of the electric fan 53 to switch the blowing direction to the exhaust direction or the intake direction.

  In the configuration of the first modification shown in FIG. 6, the filter 52 is detachable from the first air port 51 and detachable from the second air port 54. When is attached, it is preferable that the filter 52 can be replaced with the second air port 54. By replacing the filter 52 with the second air port (exhaust port) 54, the filter 52 and the built-in filter 58 of the exhaust purification unit 50 are provided double (in series) on the exhaust side, and ultrafine particles are captured. Collection efficiency can be increased.

  Next, a second modification of the image forming apparatus of this embodiment is shown in FIGS. FIG. 9 is a schematic side view showing the flow of cooling air inside the printer unit 1 before the exhaust cleaning unit 50 is mounted in the second modification. FIG. 10 is a schematic side view illustrating the flow of cooling air inside the printer unit 1 after the exhaust cleaning unit 50 is mounted. In the image forming apparatus according to the second modification, as shown in FIG. 9, an exhaust fan (electric fan) 42 is disposed in the exhaust port 41 of the printer unit 1, and no intake fan is provided in the intake port 40. In this case, as described in the first modified example, since the intake fan is not disposed at the intake port 40, the air flow is slow at a place away from the exhaust fan 42, and the cooling efficiency of the paper P becomes high speed printing. There are problems such as lowering.

  However, in the image forming apparatus according to the second modification, the exhaust purification unit 50 including the exhaust fan 55 can be mounted outside the exhaust port 41, and the electric fan 42 can be attached to and detached from the exhaust port 41. At the same time, it can be attached to and detached from the intake port 40. As shown in FIG. 10, when the exhaust purification unit 50 is mounted, the electric fan 42 can be replaced with the intake port 40 to function as an intake fan. As a result, the same configuration and effect as the embodiment shown in FIGS. 3 and 4 can be realized. Further, in the configuration shown in FIG. 10, the filter 43 mounted inside the exhaust port 41 and the built-in filter 58 of the exhaust purification unit 50 work double (in series), thereby improving the collection efficiency of ultrafine particles. Can do.

  In the second modified example, as described in the first modified example, a mounting sensor S1 (see FIGS. 5 and 6) for detecting whether or not the exhaust purification unit 50 is mounted may be provided. And in the 1st modification and the 2nd modification, it is preferred that control part 28 adjusts the air volume of an electric fan (intake fan) based on the detection signal of wearing sensor S1. A flowchart of an example of this control is shown in FIG.

  In step # 201 of FIG. 11, the control unit 28 checks whether or not the exhaust purification unit (CU) 50 is mounted based on the detection signal of the mounting sensor S1. If the exhaust purification unit 50 is not attached, the process is terminated without changing the air volume of the intake fan. If the exhaust purification unit 50 is installed, the control unit 28 checks in step # 202 whether or not to place importance on sheet cooling. If not, in step # 203, the control unit 28 further collects ultra fine particles (UFP). Check whether or not the emphasis is on. For example, by using the operation panel 103 in advance, the user sets whether to place importance on sheet cooling or UFP collection when the exhaust purification unit 50 is mounted, and the control unit 28 stores the setting contents in the RAM. Remember. The control unit 28 makes the above determination with reference to this stored value (flag).

  If importance is placed on sheet cooling, the air volume (rotational speed) of the intake fan is increased in step # 204. As a result, the amount of cooling air (wind speed) applied to the paper P after the toner image is fixed increases, and the cooling of the paper P is promoted. When importance is attached to UFP collection, the air volume (rotational speed) of the intake fan is decreased in step # 205. As a result, the amount of ultrafine particles passing through the filter is reduced, and the UFP collection rate is improved.

  Further, the control unit 28 that determines whether or not the exhaust purification unit 50 is mounted based on the detection signal of the mounting sensor S1 may be configured to change the fixing temperature (target temperature). As described above, the control unit 28 controls the feedback of the fixing heater H1 so that the surface temperature of the fixing roller 31 becomes the target temperature based on the detection signal of the temperature sensor T1 that detects the surface temperature of the fixing roller 31. Temperature control). For example, when the exhaust cleaning unit 50 is not installed, the target temperature of the fixing temperature is set to 165 ° C., and when the exhaust cleaning unit 50 is installed, it is set to a higher 170 ° C.

  By setting the target temperature of the fixing temperature higher, when the exhaust cleaning unit 50 is mounted and the air flow rate of the intake fan is increased as described above, the paper conveyance speed is increased and the printing speed (productivity) is increased. be able to. That is, when the exhaust cleaning unit 50 is mounted, the control unit 28 controls the air flow of the intake fan, the control to increase the target temperature of the fixing temperature, and the paper transport via the paper transport mechanism M1. Control that increases the speed can be performed as a set. Thereby, for example, the printing speed of plain paper can be increased from 30 ppm to 35 ppm. Alternatively, the printing speed of cardboard can be made equal to the printing speed of plain paper when the exhaust cleaning unit 50 is not installed.

  Further, the control unit 28 that determines whether or not the exhaust purification unit 50 is mounted based on the detection signal of the mounting sensor S1 may be configured to release the restriction on the attributes of the usable paper P. . For example, the user sets the attributes (thickness, etc.) of the paper P to be used in advance using the operation panel 103 or the like, and the control unit 28 stores the setting contents in the RAM. As the thickness of the paper P increases, the amount of heat of the paper P increases, so it is necessary to reduce the printing speed accordingly. In other words, it is necessary to limit the attributes such as the thickness of the paper P in order to maintain the steady printing speed.

  However, when the exhaust cleaning unit 50 is installed, the paper cooling performance is improved by increasing the air flow of the intake fan as described above. Therefore, the target temperature of the fixing temperature is set to be higher and the paper conveyance speed is increased. be able to. Therefore, the control unit 28 can cancel the restriction on the attribute such as the thickness of the paper P instead of increasing the paper conveyance speed. For example, the upper limit 90 gsm of the basis weight of the usable paper can be canceled, and it is possible to deal with a paper having a basis weight of 105 gsm. Alternatively, it is possible to use cardboard or special paper having a large heat capacity.

  Although the embodiments of the present invention and the modifications thereof have been described above, the shape and structure of each part are not limited to the specific ones described with reference to the drawings, and do not depart from the spirit of the present invention. Various changes can be made.

DESCRIPTION OF SYMBOLS 1 Printer part 2 of image forming apparatus 2 Case 5 Fixing device 28 Control part 30 Paper conveyance path 40 Intake port 41 Exhaust port 42 Exhaust fan (electric fan)
43, 52 Filter 44 Intake fan 50 Exhaust cleaning unit 51 First air port 53 Electric fan 54 Second air port 55 Exhaust fan P with built-in exhaust cleaning unit Recording material (paper)
S1 wearing sensor

Claims (13)

An exhaust port provided in the housing for exhausting air in the vicinity of the paper conveyance path after toner image fixing;
A filter and an exhaust fan disposed at the exhaust port;
An intake port provided on the surface of the casing opposite to the exhaust port across the transport path;
An intake fan disposed at the intake port;
Air sucked from the outside by the intake fan flows in a direction parallel to the surface of the sheet passing through the conveyance path and perpendicular to the sheet conveyance direction, and then discharged to the outside by the exhaust fan through the filter. An image forming apparatus. The exhaust port, the exhaust fan, the intake port, and the intake fan are arranged so that air sucked from outside by the intake fan flows along both front and back surfaces of the sheet passing through the conveyance path. The image forming apparatus according to claim 1. A first air port provided in the housing for exhausting air in the vicinity of the paper conveyance path after fixing the toner image;
A filter and an electric fan disposed in the first air port;
A second air port provided on a surface of the casing opposite to the first air port across the transport path,
An exhaust purification unit incorporating an exhaust fan can be mounted outside the second air port,
A sensor for detecting attachment of the exhaust purification unit, and a control unit for reversing the blowing direction of the electric fan based on a detection signal of the sensor;
When the exhaust purification unit is not installed, the control unit causes the electric fan to function as an exhaust fan, and when the exhaust purification unit is installed, the electric fan functions as an intake fan, The air sucked from the outside by the electric fan flows in a direction parallel to the surface of the sheet passing through the conveyance path and perpendicular to the sheet conveyance direction, and then discharged to the outside through the exhaust purification unit. Image forming apparatus. The filter is detachable from the first air port and detachable from the second air port. When the exhaust purification unit is not mounted, the filter is attached to the first air port. The image forming apparatus according to claim 3, wherein the image forming apparatus is attached to an opening, and the filter can be replaced with the second air opening when the exhaust purification unit is attached. The image forming apparatus according to claim 3, wherein the control unit reverses a blowing direction by changing a direction of a case of the electric fan. The image forming apparatus according to claim 3, wherein the control unit reverses a blowing direction by changing a rotation direction of blades of the electric fan. An exhaust port provided in the housing for exhausting air in the vicinity of the paper conveyance path after toner image fixing;
A filter and an electric fan disposed at the exhaust port;
An intake port provided on the surface of the casing opposite to the exhaust port across the conveyance path,
An exhaust purification unit with a built-in exhaust fan can be mounted outside the exhaust port,
The electric fan is attachable / detachable to / from the exhaust port, and is attachable / detachable to / from the intake port. When the exhaust purification unit is installed, the electric fan is replaced with the intake port to take in the air. An image forming apparatus capable of functioning as a fan. The sensor according to claim 3, further comprising: a sensor that detects attachment of the exhaust purification unit; and a control unit that adjusts the air volume of the electric fan based on a detection signal of the sensor. Image forming apparatus. The image forming apparatus according to claim 8, wherein when the exhaust purification unit is attached, the control unit increases the air volume of the electric fan as compared with before the exhaust purification unit is attached. apparatus. The image forming apparatus according to claim 8, wherein when the exhaust purification unit is attached, the control unit reduces the air volume of the electric fan as compared to before the exhaust purification unit is attached. apparatus. The apparatus further includes a sensor that detects attachment of the exhaust purification unit, and a control unit that controls the fixing temperature of the fixing device to be a target temperature. The image forming apparatus according to claim 3, wherein the target temperature is set higher than before the exhaust purification unit is mounted. The sensor further includes a sensor that detects attachment of the exhaust cleaning unit, and a control unit that variably controls the sheet conveyance speed, and the control unit is configured to control the exhaust cleaning unit when the exhaust cleaning unit is attached. The image forming apparatus according to claim 3, wherein the sheet conveyance speed is set higher than before the mounting. 8. The apparatus according to claim 3, further comprising: a sensor that detects attachment of the exhaust purification unit; and a control unit that releases a restriction on the attribute of the usable paper based on a detection signal of the sensor. The image forming apparatus described in 1.

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