JP5111173B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as an offset printing machine, a printer using an electrophotographic system, a copying machine, and a FAX.

  In general, the image forming apparatus has a fan for preventing temperature rise inside the apparatus and collecting dust, and has an airflow design with a duct. FIG. 6 is a cross-sectional view of the image forming apparatus, and an example of airflow will be described. The image forming apparatus 60 is a full-color image forming apparatus in which image forming units of yellow, magenta, cyan, and black (hereinafter abbreviated as Y, M, C, and Bk) are arranged side by side on an intermediate transfer belt 605. Here, a fan that forms an air flow for supplying fresh air to the primary charging devices 612Y to 612 out of fans having various purposes as described above will be described as an example. Fresh air introduced from outside the apparatus by a suction fan 616 from a louver 615 provided on the side of the apparatus is supplied to the primary charging apparatuses 612Y to 612k by a primary charging fan duct 617 as indicated by an arrow a. The primary charging devices 612Y to Bk are devices for uniformly charging the surface of the photoconductor before forming electrostatic latent images on the photoconductors 611Y to Bk, and have charging wires. Toner and dust are scattered around the image forming unit, and when these adhere to the charging wire, a white streak-like image defect occurs. Therefore, the fresh air is guided to the front side of the primary charging devices 612Y to 612k by the primary charging fan duct 617 and exhausted to the back side of the device along the charging wire. With this configuration, the effect of preventing adhesion to the primary charging wire is aimed. A dust collection filter or the like is provided after the louver 615 to prevent dust and the like from being mixed into the fresh air.

  As can be said for not only the image forming apparatus but also for all mechanical devices, a problem in using these fans is vibration, which causes secondary problems such as noise. As a fan mounting considering vibration isolation, a configuration in which the fan is fixed with an elastic member sandwiched as in Patent Document 1 is common. However, even within the image forming apparatus, the type, shape, and size of the fan vary depending on the required air volume and the like, and in the case of the means as in Patent Document 1, a dedicated elastic member that matches each fan is required. Therefore, the versatility of parts is lacking, leading to an increase in cost. On the other hand, as disclosed in Patent Document 2, a part in which an attachment part of a part that holds a fan such as a duct is configured as an elastic member has been proposed. In patent document 2, it becomes the structure which does not require an elastic member separately by making a part of duct formed with a resin material into a resin spring shape. Even if a separate elastic member is provided, it is possible to deal with all ducts in the apparatus with simple shaped parts such as a rectangular shaped elastic sheet, so that the versatility of the parts is high.

  Furthermore, in Patent Document 2, one of the support portions of the fan duct unit is a fixed end, and the other is a simple support, and the elastic member is arranged on the simple support portion to enhance the damping effect, and more excellent. It has been proposed as a configuration that can provide an anti-vibration effect. The simple support in this specification means a support method that generates a support reaction force but does not generate a support reaction moment.

  However, the problem caused by vibration is not only noise, but image defects such as banding are particularly problems specific to the image forming apparatus. Banding appears as visual unevenness when the actual image position is periodically deviated from the ideal image position by transmitting vibrations to locations related to image formation such as a photoconductor and an exposure device. A fan arranged in the vicinity of the image forming unit such as the suction fan 616 shown in FIG. 6 transmits vibrations to the image forming unit and is likely to be an oscillation source for image defects.

  As described earlier, banding is a visual unevenness, but the frequency band that is easily recognized (conspicuous) corresponds to a relatively low frequency region of the frequency band of an oscillation source such as a fan. . In general, it is known that there is a correlation between resonance frequency and rigidity, and the higher the rigidity, the higher the resonance frequency. Therefore, it is considered that a relatively low-frequency vibration component that causes banding reaches the photosensitive member or the like through a route that transmits a portion having a low rigidity in the apparatus housing.

On the other hand, recently, a configuration in which a fan is supported by a plurality of support members has been adopted for effective use of space. When such a configuration is used, it is necessary to make all the supporting members highly rigid supporting members that do not have a resonance frequency in a low frequency region.
JP 2000-172031 A JP 2001-312188 A

  However, if all the supporting members are made to be highly rigid supporting members, the components are complicated. Therefore, there is a demand to reduce the transmission of vibrations in the low frequency region while making some of the support members have less rigid parts.

  Therefore, when a support member with low rigidity supports a fan, the structure which fastens a fan to a support member via an elastic member between a fan and a support member is mentioned.

  However, in the configuration in which the fan is fastened to the support member via the elastic member, since the effect of the elastic member is weakened, vibration in the low frequency region is easily transmitted to the support member having low rigidity. Cannot be attenuated.

  Accordingly, the present invention provides an image forming unit having an image carrier, a fan unit having a fan for forming an air flow in the image forming apparatus, a first support member for supporting the fan unit, and the fan unit. And an image forming apparatus having a second support member having a product of a longitudinal elastic modulus and a second moment of inertia larger than that of the first support member, wherein the fan unit is fixed to the second support member by a fastening member. The fan unit has a degree of freedom with respect to the first support member and is supported via an elastic member.

  According to the present invention, when a fan is supported by a plurality of support members, an image forming unit for vibration in a low-frequency region from the fan is improved even if the rigidity of some of the support members is low while improving the mountability of the fans. The transferability to can be reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment)
The image forming apparatus according to the embodiment of the present invention will be described with reference to FIG. The electrophotographic color image forming apparatus is mainly classified into a tandem method in which a plurality of image forming units are arranged side by side and a rotary method in which a plurality of image forming units are arranged in a cylindrical shape. From the viewpoint of the transfer method, the transfer method is classified into a direct transfer method in which a toner image is directly transferred from a photosensitive member to a recording material and an intermediate transfer method in which the toner image is once transferred to an intermediate transfer member and then transferred to a recording material. FIG. 6 is a cross-sectional view of an intermediate transfer tandem system in which four color image forming portions of Y, M, C, and Bk are arranged side by side on an intermediate transfer belt 605 that is an intermediate transfer member. The intermediate transfer method does not need to hold the recording material on the transfer drum or the transfer belt unlike the direct transfer method, and thus can cope with a wide variety of recording materials such as ultra-thick paper and coated paper. Furthermore, the features of parallel processing in a plurality of image forming units and batch transfer of full-color images are suitable for realizing high productivity. Hereinafter, the operation of the image forming apparatus will be described with reference to FIG.

  The recording material S is stored so as to be stacked on a lift-up device 62 included in the paper feeding device 61, and is fed by the paper feeding unit 63 in accordance with the image forming timing of the image forming unit. Here, the sheet feeding means 63 includes a method using frictional separation by a sheet feeding roller or the like, a method using separation adsorption by air, and the like. In FIG. 6, the latter sheet feeding method is used. The recording material S sent out by the paper feeding means 63 is joined to the main body transport path from the transport path 64, and is subjected to skew feeding correction and timing correction in the registration roller 65 and then sent to the secondary transfer section. The secondary transfer portion is a transfer nip portion of a toner image formed by the opposing secondary transfer inner roller 608 and secondary transfer outer roller 66, and provides a recording material by applying a predetermined pressure and electrostatic load bias. A toner image is adsorbed on S.

  With respect to the conveyance process of the recording material S up to the secondary transfer unit described above, an image forming process sent to the secondary transfer unit at the same timing will be described. The image forming unit mainly includes photoreceptors 611Y to Bk which are image carriers, exposure devices 609Y to Bk, developing devices 613Y to Bk, primary charging devices 612Y to Bk, cleaning devices 614Y to Bk, and primary transfer devices 618Y to Bk. Etc. The surface is uniformly charged in advance by the primary charging devices 612Y to Bk. Then, the exposure devices 609Y to Bk are driven to emit light on the charged surfaces of the photoconductors 611Y to Bk rotating in the direction of the arrow d in the figure, based on the transmitted image information, and diffraction means 610Y to Bk such as mirrors. The electrostatic latent image is formed through the above. The electrostatic latent images formed on the photoconductors 611Y to Bk in this way are developed with toner by the developing devices 613Y to Bk, and are visualized on the photoconductors. Thereafter, a predetermined pressure and electrostatic load bias are applied by the primary transfer devices 618Y to 618k, and a toner image is transferred onto the intermediate transfer belt 605. Thereafter, the transfer residual toner remaining on the photoreceptors 611Y to Bk is collected by the cleaning devices 614Y to Bk, and prepared for the next image formation again. The above image forming process is executed in parallel in the four image forming units Y, M, C, and Bk in the case of FIG.

  Next, the intermediate transfer belt 605 that is an intermediate transfer member will be described. The intermediate transfer belt 605 is stretched by rollers such as a driving roller 606, a tension roller 607, and a secondary transfer inner roller 608, and is conveyed and driven in the direction of arrow b in the drawing. Therefore, the image forming process of each color that is processed in parallel by the above-described Y, M, C, and Bk image forming units is performed at the timing of sequentially superimposing the toner image that is primarily transferred on the intermediate transfer belt 605 upstream. . As a result, a full-color toner image is finally formed on the intermediate transfer belt 605 and conveyed to the secondary transfer unit.

  As described above, the full color toner image is secondarily transferred onto the recording material S in the secondary transfer portion by the recording material S conveyance process and the image forming process described above. Thereafter, the recording material S is conveyed to the fixing device 68 by the pre-fixing conveyance unit 67. The fixing device 68 includes a fixing roller (image heating member) that heats the toner image on the recording material and a pressure roller (pressure member) that presses and contacts the fixing roller and sandwiches and conveys the recording material. The toner image on the recording material S is fixed on the recording material by heat and pressure. The recording material S having a fixed image obtained in this way is discharged as it is from the discharge conveyance path 69 onto the discharge tray 604, or is conveyed to the reverse conveyance path 601 when double-sided image formation is required. Route selection is performed. A switching member (not shown) such as a flapper is provided at a branch point where such route selection is performed.

  Next, a conveying operation when double-sided image formation is required will be described. After the recording material S sent to the reverse conveyance path 601 is drawn into the switchback conveyance path 602, the conveyance roller rotates backward to change the leading and trailing edges, and is conveyed to the double-side conveyance path 603. Thereafter, the sheet is fed again to the secondary transfer section through the registration roller 65 in synchronism with the timing of the recording material of the subsequent job conveyed from the sheet feeding device 61. Since the image forming process on the second side (back side) is the same as that on the first side (front side), description thereof is omitted.

  As described above, in the image forming apparatus 60, the air flow for supplying fresh air to the primary charging devices 612Y to 612k is formed by the louver 615, the suction fan 616, the primary charging fan duct 617, and the like. . The support structure of the primary charging fan duct will be described with reference to FIGS. 2, 3, and 4. FIG. Both are perspective views of the image forming apparatus 60 described with reference to FIG. 6, and for the sake of convenience, a unit unnecessary for the description is omitted, and the figure is centered on the apparatus housing. 2 is an overall perspective view showing the positional relationship between the apparatus housing and the primary charging fan duct, FIG. 3 is a partial perspective view showing a simple support portion of the primary charging fan duct, and FIG. 4 shows a fixed end support portion of the primary charging fan duct. It is a fragmentary perspective view shown. As shown in FIG. 2, a coordinate system is defined in which the left-right direction of the apparatus is the x direction, the back direction of the apparatus is the y direction, and the height direction of the apparatus is the z direction, and the + y direction side is the front of the apparatus. The primary charging fan duct 617 is disposed in the upper right part of the apparatus housing 20, and a suction port provided with a dust collection filter 27 is provided on the right side of the apparatus. The apparatus housing 20 is configured by a front plate 22 and a rear plate 25 being joined to a frame mainly composed of a bottom plate 21, a vertical frame 23, which is a column, and a horizontal frame 24. The front side plate 22 and the rear side plate 25 position and support various parts and units including the photoreceptors 611Y to Bk, and the stay 26 is one of them. In the image forming apparatus 60 shown in this embodiment, the primary charging fan duct 617 has a support structure in which one of the horizontal frames 24 (A) is the support portion A and the stay 26 is the support portion B.

  These support portions will be described in more detail with reference to FIGS. 3 and 4. As shown in FIG. 3, the primary charging fan duct 617 has an elastic member 52 attached to the pressure contact surface 31 of the fan mount 51, and the support portion B is in a state in which the elastic member 52 is crushed in the stay 26 (first The support member is in pressure contact with the support member. Here, the support portion B is a simple support that does not use a fastening means such as a screw, and is only in pressure contact with the stay 26. That is, the support portion B has a degree of freedom with respect to the stay 26. The elastic member 52 may be a member having an anti-vibration or shock-absorbing effect such as a rubber sheet or a foamed sheet, and may be a spring shape formed integrally with the pressure contact surface 31. As shown in FIG. 4, the other support portion A is a horizontal frame 24 (A) (second support member) disposed on the upper right side of the apparatus, and the primary charging fan duct 617 is a screw 40 (fastening member). It takes the form of the fixed end support fastened by. 3 to 4, the front side plate 22 is indicated by a broken line, and the primary charging fan duct 617 shown in FIGS. 2 to 4 omits a duct portion that guides fresh air along the primary charging wire portion. Only the vicinity of the suction part is displayed. Incidentally, fresh air is sucked in the direction of arrow a as shown in FIG. 3 and then delivered from the duct connection port 30 to the omitted duct portion as shown in the direction of arrow a ′. Although not shown in FIGS. 2 to 4, a fan other than the suction fan 616 is provided as necessary to guide the fresh air delivered in the direction of the arrow a ′ along the primary charging wire. It has been.

  Next, the configuration of the primary charging fan duct 617, which is a fan unit, will be described with reference to FIG. A suction fan 616 is fastened to the fan mount 51 using screws or the like, and the suction duct 50 is covered from above. Here, the gap between the suction duct 50 and the fan mount 51 is configured to be in close contact, and consideration is given to preventing air from leaking. The dust collection filter 27 is attached to the suction port of the suction duct 50, and an elastic member 52 is attached to the pressure contact surface 31 of the fan mount 51. Here, since the suction fan 616 supplies fresh air to a wide range of image forming portions from Y to Bk as shown in FIG. 6, a relatively larger fan than other fans is used to increase the air volume. ing. As can be seen from FIGS. 2 to 4, the frames and stays, which are the support portions A and B of the primary charging fan duct 617, are the same components as the photoconductors 611 </ b> Y to Bk; the front plate 22 and the rear plate 25. Is often supported by. That is, the vibration of the suction fan 616 is easily transmitted and resonated to the photoconductors 611Y to Bk, and can be cited as a typical example of an oscillation source in which the influence on image defects such as banding is concerned. FIG. 7 is a graph showing single vibration of the primary charging fan duct 617. This graph is vibration data measured using an acceleration pickup in which the primary charging fan duct 617 is suspended and supported by a thread or the like so as not to be affected by the fastening state or the like. Generally, a fan has vibration components in the rotational direction and the axial direction. FIG. 7 shows the vibration component in the rotational direction having a relatively large vibration level. As can be seen from FIG. 7, it can be seen that there is a relatively low frequency component peaking at about 87 Hz and a relatively high frequency component band peaking at about 350 Hz. If the process speed of the image forming apparatus 60 shown in FIG. 6 is 300 mm / s, a relatively low frequency component appears as a banding with a pitch of about 3.4 mm, and a high frequency component band appears as a banding with a pitch of about 0.8 mm. FIG. 8 shows image analysis data when the primary charging fan duct 617 provided with the suction fan 616 having vibration shown in FIG. 7 is screwed together (fixed end support) together with the support portions A and B. The waveform in FIG. 8 is a waveform obtained by forming lines at equal intervals with a process speed of 300 mm / s in the sub-scanning direction and measuring how much the actual line position deviates from the theoretical nominal position. Is further frequency-analyzed. FIG. 8 shows that about 87 Hz, which is the vibration component of the suction fan 616, appears prominently in the actual image. At the same time, vibrations in a higher frequency band including about 350 Hz also appear, but as described above, these are very fine pitches of about 0.8 mm or less, and are not easily recognized visually. On the other hand, since the vibration component of about 87 Hz has a pitch of about 3.4 mm, the unevenness is visually noticeable and recognized as banding.

FIG. 9 shows the same frequency analysis result when the primary charging fan duct 617 is supported by the supporting method according to the present invention shown in FIGS. As is apparent from FIG. 9, it can be seen that a vibration component of about 87 Hz that is easily recognized as banding is effectively attenuated. The reason why the vibration component having a relatively low frequency is attenuated will be described with reference to FIG. FIG. 1 is a schematic diagram showing a cross section of the support structure of the primary charging fan duct 617 shown in FIG. 2 taken along the xz plane. As described above, in the primary charging fan duct 617, the horizontal frame 24 (A) as the support portion A is supported by the fixed end by the screw 40, and the stay 26 (B) as the support portion B is provided with the elastic member 52. Simple support is provided by non-fastening pressure contact. Here, the horizontal frame 24 (A), which is the support portion A, has a hollow square pipe cross section (hatching instruction portion in FIG. 1) having an mxn dimension formed by bending a sheet metal member having a sheet thickness t1. In addition, the stay 26 (B) as the support portion B has a thin rectangular cross section w × t2 (hatching instruction portion in FIG. 1) whose z direction is only the plate thickness t2. Since the support portion A is fastened with the screw 40 from the x direction, the vibration of the suction fan 616 is transmitted from the x direction as indicated by an arrow α in the figure. That is, the external force due to vibration mainly acts on the lateral frame 24 (A) as the support portion A from the x direction, and the cross-sectional secondary moment I _{z with} respect to the vibration is
^{_{I z = mn 3 / 12- (}} m-2t) (n-2t) 3/12 ··· (1)
Represented as: On the other hand, since the support portion B is pressed by the elastic member 52 from the z direction, the vibration of the suction fan 616 is transmitted from the z direction as indicated by an arrow β in the figure. That is, the external force due to the vibration mainly acts on the stay 26 (B) as the support portion B from the z direction, and the cross-sectional secondary moment I _{x with} respect to the vibration is
^{_{I x = wt 3/12 ···}} (2)
Represented as: In the image forming apparatus 60 shown in FIG. 6, m = 60 mm, n = 30 mm, t1 = 2.3 mm, t2 = 1.6 mm, and w = 75 mm. From the expressions (1) and (2), I _z = about 5.9 cm ⁴ and I _x = about 0.0026 cm ⁴ , and the support portion A is set to a larger value. The material is an electrogalvanized steel plate for both the lateral frame 24 (A) and the stay 26 (B), and the longitudinal elastic modulus E is the same. Therefore, regarding the bending rigidity EI _z and EI _{x with} respect to each vibration, the lateral frame 24 (A) that is the support portion A has higher rigidity than the stay 26 (B) that is the support portion B.

  A unit represented by a fan duct unit needs to be fixed in position in order to suppress pressure loss due to air leakage or the like. However, in this embodiment, by using a support method having both a fixed end support and a simple support by non-fastening pressure contact as described above, a system that basically does not transmit vibration from the support B is constructed. Yes. However, in an actual apparatus, there is a difference in rigidity between both support members as shown in the above formulas (1) and (2). In the case of phenomena such as banding, where the frequency band and visibility are closely related, it may not be possible to take advantage of the system that is difficult to transmit the bending vibration unless the combination of the support method and rigidity difference is considered. It is done. Specifically, if the fixed-end support is brought to the support member having relatively low rigidity, a relatively low frequency component that is easily recognized as banding eventually resonates and transmits to the support portion A side. The merit of the support method cannot be fully utilized. In the present embodiment, in consideration of the above, the support portion A having relatively high rigidity; the fixed end support on the lateral frame 24 (A), and the support portion B having relatively low rigidity; simply on the stay 26 (B). Arrange support. As a result, the approximately 87 Hz component already described with reference to FIG. 7, that is, the relatively low-frequency vibration component that is easily recognized as banding, is supported by the support portion B; B) tends to resonate. Further, a relatively high frequency vibration band is likely to resonate with the support portion A; the lateral frame 24 (A) having relatively high rigidity as indicated by an arrow α in the figure. In this way, by intentionally providing a rigidity difference such that the support portion A> the support portion B, a system that is unlikely to be recognized as banding even if it resonates from the support portion A that has been fixed in position. it can. Further, since the elastic member 52 is provided in the non-fastening pressure contact state in the support portion B, even if a low frequency component that directly affects banding resonates, it is rather concentrated as indicated by an arrow β ′ in the figure. The system can be attenuated to As a result, the image forming apparatus as a whole is a system in which low-frequency vibration components (about 87 Hz in this example) are difficult to be transmitted to the photoconductors 611Y to Bk, and an image forming apparatus having a configuration strong against banding can be realized.

  Incidentally, the image analysis data when the supporting method other than the present invention is performed is shown in FIGS. 10 and 11 for reference. FIG. 10 shows image analysis data when the screw fastening is also performed on the stay 26 (B) as the support portion B in the configuration of the present invention described in FIG. From the graph, it can be seen that the approximately 87 Hz component that directly affects banding appears in the image without being attenuated. This indicates that the stay 26 (B) resonates with a low-frequency vibration component if the elastic member 52 is sandwiched between the stays 26 (B) when they are fastened with screws or the like. It can be seen that the configuration in which the elastic member 52 is pressed in a non-fastened state as in the present invention has a damping effect. FIG. 11 shows image analysis data when an elastic member is sandwiched between the horizontal frame 24 (A) as the support portion A in addition to the configuration of FIG. 10. From the graph, it can be seen that banding at a pitch of about 3.4 mm (= about 87 Hz) appears in the image, and basically there is no significant difference from FIG. That is, even if a damping means such as an elastic member is provided in the support portion A having relatively high rigidity, the effect is low for a relatively low frequency vibration component that is easily recognized as banding. And the effectiveness of paying attention to the correlation of the rigidity of a support part and resonance frequency which were demonstrated by this invention is understood.

Here, as can be seen from FIGS. 2 to 4, in this embodiment, the horizontal frame 24 (A) as the support portion A and the stay 26 (B) as the support portion B are both the same distance between the side plates. This is a support condition for fixing both ends. Furthermore, since the external force acting position due to vibration is almost the same, the magnitude relationship of rigidity can be discussed only by the difference in the second moment of the cross section of the two support portions as described above. However, the magnitude of rigidity can be regarded as the magnitude of displacement caused by an external force caused by vibration. Therefore, it is necessary to consider the distance from the fixed support portion of the lateral frame 24 (A) or the stay 26 (B) to the position where the external force is caused by vibration as a parameter expressing the rigidity of the support portion. Therefore, in this embodiment, the horizontal frame 24 (A) is attached to the support column 23 of the housing, and the stay 26 (B) is attached to the front side plate and the rear side plate. The length of the horizontal frame 24 (A) is smaller than the length of the stay 26 (B) by the thickness of the support post 23 × 2. Specifically, the distance (450 mm) between the fan unit and the support portion of the horizontal frame 24 (A) and the horizontal frame 24 (A) and the housing is determined by the support portion of the fan unit and the stay 26 (B) and the stay 26 (B). It is smaller than the interval (465 mm) between B) and the housing. The interval is the longer interval (Y-direction), and the shorter interval (Y + direction) is 250 mm for the former and 265 mm for the latter, and this relationship is shown in both directions in the Y direction. Satisfies. Moreover, since it is considered the vibration caused by the bending twisting direction of the external force not only the direction, in the case of rigidity against the torsional vibration of the product GI _p of shear modulus G and sectional secondary polar moment I _p of the two support portions It is necessary to consider the size relationship. Therefore, in this embodiment, the GI _p of the horizontal frame 24 (A) is larger than the GI _{p of the} stay 26 (B). In this embodiment, I _p = I _Z + I _X = 5.9 + 18 = 23.9 cm ^{4 of} the horizontal frame 24 (A), I _p = I _Z + I _X = 5.6 + 0.0026 = of the stay 26 (B). 5.6026 cm ⁴ . Since the materials of the horizontal frame 24 (A) and the stay 26 (B) are the same, the values of G are equal. Therefore, the GI _p of the horizontal frame 24 (A) is configured to be larger than the GI _{p of the} stay 26 (B).

As described above, the rigidity defined in the present invention includes the material (that is, the longitudinal elastic modulus E or the shear elastic modulus G), the cross-sectional shape (that is, the cross-sectional secondary moment I or the cross-sectional secondary pole moment I _p ), and vibration. This means the difficulty of displacement (that is, resistance) that comprehensively determines the applied position of the external force (that is, the magnitude of the generated bending moment).

  In the present embodiment, the fan that causes banding is the suction fan 616 provided in the primary charging fan duct 617, but of course, a fan provided for other purposes may be used. Further, regarding the form of banding, vibration transmission to the photoconductors 611Y to Bk is given as an example, but the same problem is considered for other objects related to image formation such as an exposure device, a developing device, and a transfer device. Therefore, the effect of the present invention can be expected. Further, the image forming apparatus shown in FIG. 6 is a tandem color image forming apparatus, but the number of colors, the configuration, the method of the image forming process, etc. are particularly limited if the image forming apparatus has a problem of image defects due to banding. It doesn't matter.

It is a cross-sectional schematic diagram which shows the support structure of a primary charging fan duct. It is a whole perspective view which shows the positional relationship of an apparatus housing | casing and a primary charging fan duct. It is a fragmentary perspective view which shows the simple support part of a primary charging fan duct. It is a fragmentary perspective view which shows the fixed end support part of a primary charging fan duct. It is a perspective view shown about the structure of a primary charging fan duct. 1 is a cross-sectional view illustrating an image forming apparatus. It is the measurement data of the single vibration of a primary charging fan duct. It is image frequency analysis data (the 1) when not implementing this invention. It is image frequency analysis data at the time of implementing this invention. It is image frequency analysis data (the 2) when not implementing this invention. It is image frequency analysis data (the 3) when not implementing this invention.

Explanation of symbols

20 Device housing 21 Bottom plate 22 Front side plate 23 Vertical frame 24 (A) Horizontal frame (supporting part A)
25 Rear plate 26 (B) Stay (support B)
27 Dust collection filter 30 Duct connection port 31 Pressure contact surface 40 Screw 50 Suction duct 51 Fan mount 52 Elastic member 60 Image forming device 61 Paper feed device 62 Lift-up device 63 Paper feed means 65 Registration roller 66 Secondary transfer outer roller 67 Before fixing Conveying section 68 Fixing device 69 Discharge transport path 601 Reverse transport path 602 Switchback transport path 603 Duplex transport path 604 Discharge tray 605 Intermediate transfer belt 606 Drive roller 607 Tension roller 608 Secondary transfer inner roller 609 Exposure device 610 Diffraction means 611 Photoconductor 612 Primary charging device 613 Developing device 614 Photoconductor cleaner 615 Louver 616 Suction fan 617 Primary charging fan duct 618 Primary transfer device

Claims (4)

An image forming unit having an image carrier, a fan unit having a fan for forming an air flow in the image forming apparatus, a first support member supporting the fan unit, and supporting the fan unit, In an image forming apparatus having a second support member having a product of a longitudinal elastic modulus and a cross-sectional second moment greater than that of the support member,
The fan unit is fixed to the second support member by a fastening member, and the fan unit has a degree of freedom with respect to the first support member and is supported via an elastic member. An image forming apparatus.   The image forming apparatus according to claim 1, wherein the second support member has a larger product of a shear elastic modulus and a cross-sectional secondary pole moment than the first support member.   3. The image forming apparatus according to claim 1, wherein the second support member is supported by a support column constituting a housing of the image forming apparatus.   The image forming apparatus according to claim 1, wherein the first support member is supported by a side plate that supports the image carrier.

Images