JP2007279148A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of maintaining a high image quality by stabilizing rotation of a plurality of driving and driven rotating rollers around which a multi-purpose endless belt member is hung on, thereby stabilizing the running speed of a belt member. <P>SOLUTION: The endless belt member 22 is hung between the driving roller 21 and the driven roller 24 and revolved. A rotational axial line for the driven roller 24 is made slidable, and tension for the belt member 22 is increased by a belt tension spring 26. An inertia 30 (inertia increasing means) is attached coaxially to the driven roller 24 and is made to have the greatest rotating inertia force among the rotating rollers including the driving roller 21. Thus the running revolutionary speed of the belt member 22 is stabilized, and an image of high image quality can be formed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, a printer, and a multifunction machine, and more particularly, is equipped with an endless belt member used for an image carrier, an intermediate transfer body of an image, and an electrostatic adsorption transport body of a recording medium. The present invention relates to an image forming apparatus.

  In an image forming apparatus, an endless belt member is wound around a plurality of driving and driven rotating rollers to transmit rotational power from a rotational driving source, and the belt member is used for various applications described above. Can function. In that case, if the running speed of the belt member is influenced by torsional vibrations generated in the rotating rollers of the drive system and transmission system, the image quality is degraded. In order to solve such a problem, for example, Patent Document 1 discloses a belt rotation drive device provided with a “centrifugal pendulum type vibration absorbing means” such as an inertia disk on the same axis as a roller rotation axis.

JP 2002-250400 A

  However, the belt rotation driving device of the above publication has the following problems to be solved. In order to stabilize the rotation speed of the belt member during traveling, the main point is to stabilize the rotation of the driving roller and absorb the belt fluctuation component. That is, although the goal is to stabilize the rotation of the belt member, the range of control and monitoring does not reach the running stability of the belt member itself. Further, attention should be paid not only to the driving roller but also to the rotation stabilization of the driven roller, but no consideration is given to this.

  As described above, an object of the present invention is to provide an endless belt member for multi-functional use in an image forming apparatus, in which the rotation of a plurality of driving and driven rotating rollers to be wound is stabilized, and the traveling speed of the belt member is increased. An object of the present invention is to provide an image forming apparatus that can stabilize and maintain high image quality.

In order to achieve the above object, an image forming apparatus of the present invention is an image forming apparatus having an endless belt and a plurality of rotating bodies around which the belt is wound.
One of the plurality of rotating bodies is supported so as to be able to move the position of the rotation axis, and the rotational inertia force is larger than that of the other rotating bodies and is maximum.

  According to the image forming apparatus of the present invention, among the plurality of rotating bodies that are wound and run around the belt member, one of the rotating bodies that is slidable in the position of the rotation axis and gives disturbance to the belt member is By configuring so that the force is maximized, the running rotation speed of the belt member is stabilized, and a high-quality image can be formed.

  Hereinafter, a preferred embodiment of an image forming apparatus will be described in detail with reference to the drawings.

  As shown in FIG. 1, a sheet P such as a recording sheet stacked in a cassette is sent from the paper feeding unit 1 to the registration roller 23 by the paper feeding / conveying roller 7, aligned, and then sent to the secondary transfer roller 9. The photosensitive drum 3 in the cartridge 2 exposed by the scanner unit 10 is developed with a developer (toner) image by the developing sleeve 4 of the process means acting thereon. The toner image is wound around the driving roller 21 and the driven roller 24 and transferred to the endless belt member 22 that rotates in the counterclockwise direction from the right side to the left side in the drawing (primary transfer). . The belt member 22 carrying the toner image by the primary transfer continues to travel as it is, and reaches the contact nip portion with the secondary transfer roller 9. Here, the toner image is secondarily transferred to the sheet P and sent to the fixing device 11. After the fixing is completed, the sheet P is discharged to the discharge tray 13 by the paper discharge roller 12. This completes the printing on one side of the sheet P.

  When printing on both sides of the sheet P, the sheet P is not completely discharged by the sheet discharge roller 12, but the sheet discharge roller 12 is reversed while the rear end of the sheet P is pinched, and the both-side refeed conveyance path 15 To guide. The double-sided paper refeed / conveyance roller 16 re-feeds the sheet P until just before the registration roller 23 and waits for the timing of toner image transfer to the second side (back side).

  In FIG. 1, the residual toner that has not been transferred by the secondary transfer roller 9 is peeled from the belt member 22 by the cleaning blade 28 attached in the counter direction with respect to the belt running direction, and passes through the waste toner transport pipe 31 to be the waste toner. Stored in box 33.

(First embodiment)
FIG. 2 shows a cross section of the belt drive unit 20 mainly composed of the belt member 22. The position of the rotational axis of the driving roller 21 that is wound around the belt member 22 is fixed without change, and the position of the rotational axis of the driven roller 24 is slidable in the lateral direction. The driven roller 24 is moved and energized by pulling the rotation axis away from the driving roller 21 by a tension spring 26 in the left direction in the drawing, and functions as a tension roller that applies an appropriate tension to the belt member 22. However, in the present embodiment, the driven roller 24 is configured as a tension roller, but the third, fourth,... Intermediate rollers and idler (play) pulleys that are non-driving rollers other than the driven roller 24 are used as tension rollers. You can also.

  FIG. 3 shows the belt drive unit 20 as seen from the plane in the direction of arrow Z in FIG. Side plates R41 and L42 are provided on both left and right sides of the unit, and roller shaft holes 41a and 41b and 41a and 41b are provided through these side plates. The driving roller 21 and the driven roller 24 are pivotally supported in these roller shaft holes by fitting the respective roller shaft end portions 21a and 24a to be rotatable.

  Here, for each of the driving roller 21 and the driven roller 24, in order to qualitatively understand the rotational fluctuation by replacing the support state with numerical values, the spatial freedom of each roller is defined as follows as one method.

  Typically, the degree of freedom of space for the drive roller 21 is defined. Now, let it be assumed that the drive roller 21 is free to move in all directions of XYZ on the coordinate axis and is not restricted in any direction. Further, it is assumed that the drive roller 21 is free to rotate around each axis of the XYZ axes. In this case, the degree of spatial freedom can be expressed by a numerical value “6”. The larger the value of the degree of freedom in space, the judgment material can be recognized that it can be recognized that “the influence is great” on the rotation of the belt member 22.

  Actually, in the driving roller 21 of the present embodiment, only rotation around the X axis is allowed. Therefore, the degree of freedom of space of the driving roller 21 in this case can be expressed by “1”. The influence on the turning travel is small.

  In addition, as shown in FIG. 3, a rotary joint 38 is coupled to one side of the roller shaft end 21a of the drive roller 21. Rotational power output from a rotation drive source motor (not shown) provided on the image forming apparatus main body side is appropriately decelerated and transmitted to the drive roller 21 via the rotary joint 38, and the drive roller 21 is shown in FIG. Rotate clockwise. The peripheral surface portion 21b of the drive roller 21 is provided with any one member of vulcanization adhesion, press-fit fixation, and adhesion fixation as a friction increasing means for preventing slippage with the belt 22 member and increasing friction. . As the friction increasing means, the roller peripheral surface portion 21b is provided with a surface treatment including painting, coating and plating, or any surface roughening treatment including shot peening, sand blasting, uneven processing and minute protrusion processing. But it is possible.

  On the other hand, the driven roller 24 is rotatably held by a U-shaped holder 25 having a full distance between the side plates R41 and L42, and a roller shaft long hole 41a provided in both side plates via the holder 25. , 41b are rotatably supported by roller shaft end portions 24a, 24b. That is, the roller shaft end portions 24a and 24b can move in the sliding direction by the length of the roller shaft long holes 41a and 41b. The holder 25 is locked to one end of the belt tension spring 26 and pulls and urges the entire driven roller 24 together with the holder 25 in the direction of arrow Y away from the driving roller 21 in the left direction in the figure. Thereby, an appropriate tension acting in the direction of the symbol T is applied to the belt member 22. The other end of the belt tension spring 26 is secured to the unit rear side plate 43. An inertia 30 is fixed to the roller shaft end 24a on at least one end side of the driven roller 24 as an inertia increasing means for increasing the rotational inertia force on the same axis.

  As a result, the degree of freedom of space of the driven roller 24 can be expressed by “2” because rotation around the X axis and sliding movement in the Y direction are allowed while being held by the holder 25. .

  Similar to the driving roller 21, the peripheral surface portion 24b of the driven roller 24 is also subjected to processing suitable for the above-described surface processing that prevents slipping with the belt member 22 and increases friction. Thereby, the speed fluctuation restraining force of the driven roller 24 due to inertia can be sufficiently reflected on the belt member 22.

  Next, the rotational speed fluctuation (%) of the driving roller 21 and the driven roller 24 and the running speed fluctuation (%) of the belt member 22 can be expressed by the following equation (1) by converting the rotational speed into voltage. it can.

Speed fluctuation (%) = Maximum fluctuation voltage / Average voltage during steady rotation X100 (1)
Hereinafter, the rotational speed fluctuation and the running speed fluctuation “W / F (%)” are abbreviated.

  FIG. 4 is a block diagram showing a configuration of an apparatus for measuring the W / F. An optical encoder (encoder) 51 is connected to one side of the roller shaft end 21a of the drive roller 21 via a rotary joint 51a. An optical encoder 52 is connected to one side of the roller shaft end 24a of the driven roller 24 via a rotary joint J52a. Further, an optical reflective linear encoder 54 is attached to the entire circumference of the belt member 22 outside the region where the toner image or the sheet P of the belt member 22 is sucked and conveyed. In a region where the reflected light of the linear encoder 54 can be detected, a photoelectric sensor 53 that outputs light brightness and darkness with a voltage rectangular wave is installed.

  The edge intervals of the voltage rectangular wave obtained from the optical encoders 51 and 52 and the photoelectric sensor 53 include speed information. Within each Wow / Flatter meter, the three types of signals such as the encoder are speed-changed (%) according to the above equation (1) after F / V conversion and are displayed as numerical values as needed. This is referred to as a read value “1”.

  From each Wow / Flatter meter, an analog voltage waveform from which only the speed fluctuation component is extracted is output to the FFT analyzer, converted into a Fourier series inside the FFT analyzer, and the frequency spectrum of each speed fluctuation is displayed. Is done.

  By adopting the measuring apparatus and measuring method as described above, the following three items are included: the rotational speed variation (%) of each of the driving roller 21 and the driven roller 24 and the traveling speed variation (%) of the belt member 22. A total of nine measurement results are obtained by setting different types of roller inertia amounts.

  Here again, the spatial degree of freedom of the drive roller 21 is “1” because only rotation around the X axis is allowed, and the driven roller 24 rotates around the X axis and slides in the Y direction. Since movement is permitted, the degree of freedom in space is “2”.

  FIG. 5 shows a device at the time of no inertia setting for obtaining the experimental value of W / F (%) in a state where the inertia 30 as the inertia increasing means is not attached to either the driving roller 21 or the driven roller 24. Are referred to as <Comparative Example 1>. That is, the belt driving unit 20 in the case where the driving roller 21 and the driven roller 24 are set to the same inertial force is assumed.

  FIG. 6 shows an apparatus at the time of setting the drive shaft inertia for obtaining the experimental value of W / F (%) when the inertia 30 is attached only to the drive roller 21 to obtain the rotary body having the maximum rotational inertia force. This device is referred to as <Comparative Example 2>.

  FIG. 7 shows an apparatus at the time of setting the driven shaft inertia to obtain the experimental value of W / F (%) when the inertia 30 is attached only to the driven roller 24 to obtain a rotating body having the maximum rotational inertia force. Is referred to as an embodiment, and is hereinafter referred to as an apparatus of <Example 1> for convenience.

  5 to 7, the respective W / values obtained from the experimental results of <Comparative Example 1> without inertia setting, <Comparative Example 2> with driving shaft inertia setting, and <Example 1> with driven shaft inertia setting are shown. The reading 1 is plotted in the graph of FIG.

  As is apparent from FIG. 8, the W / F (%) value in the case of <Comparative Example 2> in which the inertia 30 is attached to the driving roller 21 does not attach the inertia 30 to both the driven roller 24 and the driving roller 21 <Comparative Example It is almost the same as the W / F (%) value in the case of 1>. On the other hand, the W / F (%) value of <Example 1> of the present embodiment is the belt member other than the driven roller 24 whose inertia amount is increased by attaching the inertia 30 to the driven roller 24. 22. It is considerably lower than the W / F (%) of the drive roller 21.

  In this sense, the rotation W / F (%) of the driven roller 24 in the case where the degree of spatial freedom is “2” is larger than that in the case of the driving roller 21 having the degree of spatial freedom “1”, the added inertial mass ( This shows that the inertia has been effectively suppressed by the inertia 30). In addition, it means that the added inertial mass suppresses vibration or minute displacement in the Y direction, thereby stabilizing the running of the belt member 22.

  As described above, attention has been paid to W / F (%), which is the amount of speed variation in the entire band, based on the experimental results with and without the inertia 30 being applied. In FIG. 9, the horizontal axis represents frequency, and the vertical axis represents three types of inertia settings of <Comparative Example 1>, <Comparative Example 2>, and <Example 1> for each frequency of 800 Hz or less measured by the driving roller 21. The rotational speed fluctuation component amount (dB) in the case of. FIG. 10 shows the effect of the measurement result in the drive roller 21 by comparing <Example 1> with <Comparative Example 1>, and the frequency is plotted on the horizontal axis and the effect (dB) is plotted on the vertical axis. In this case, <Example 1> is indicated as a negative region if the rotational speed fluctuation component is reduced compared to <Comparative Example 1>, a positive region if it is increased, and 0 if it is exactly the same. According to this, at a frequency of 100 Hz or less, which is considered to be a cause of image defects that are conspicuous with the human eye, the fluctuation component is reduced in <Example 1> compared to <Comparative Example 2>, and the maximum effect is 58 Hz. About -24 dB. FIG. 11 also shows <Embodiment 1> in comparison with <Comparative Example 2> about the effect (dB) of the measurement result in the drive roller 21. According to this, the rotational speed fluctuation component of <Example 1> decreases compared to <Comparative Example 2>, a negative region, a positive region when it increases, and 0 if exactly the same. That is, an increase peak of 17.8 dB is seen at 164 Hz. At a frequency of 100 Hz or less, which is considered to be a cause of image defects that are conspicuous with the human naked eye, the setting of the present embodiment has less variation components than the conventional setting, and the maximum effect is about −24.7 dB at 34 Hz. It is.

  As is apparent from the effects of <Example 1> and <Comparative Examples 1 and 2> in the driving roller 21 shown in FIGS. 10 and 11, when the inertia is not set at the rotational speed fluctuation component frequency of the driving roller 21 of 100 Hz or less. There are fewer rotational fluctuation components than any of the drive inertia settings. Moreover, it was confirmed that the rotation was stable.

  On the other hand, FIG. 12 shows the travel speed fluctuation component amount (dB) for each frequency of 800 Hz or less, as a result of measurement with the belt member 22 when the above three types are set. FIG. 13 shows the effect (dB) in the belt member 22 for <Example 1> in comparison with <Comparative Example 1>. According to this, it is indicated as a negative region when the rotational speed fluctuation component of <Example 1> decreases, a positive region when it increases, and 0 when it is exactly the same as in <Comparative Example 1>. At a frequency of 100 Hz or less, which is considered to be a cause of image defects that are conspicuous with the human eye, the setting of the present invention has a reduced fluctuation component with respect to the initial setting, and the maximum effect is about 12.7 dB at 73 Hz. . Even in the region of 100 Hz or higher, an effect of about -10.7 dB is obtained at 433 Hz.

  FIG. 14 shows the effect (dB) in the belt member 22 in the case of <Example 1> in comparison with <Comparative Example 2>. If the rotational speed fluctuation component of <Example 1> decreases rather than <Comparative Example 2>, it is indicated as a negative region, if it increases, it is indicated as a positive region, and if it is exactly the same, it is indicated as 0. At a frequency of 100 Hz or less, which is considered to be a cause of image defects that are conspicuous with the human eye, the setting of the present invention has less fluctuation components than the conventional setting, and the maximum effect is about −9.8 dB at 45 Hz. is there. Even in the region of 100 Hz or higher, an effect of about −8.6 dB is obtained at 444 Hz.

  That is, as is apparent from the belt member 22 of <Example 1> shown in FIGS. 13 and 14, <Comparative Example 1> when the inertia is not set at the traveling speed fluctuation component frequency of the belt member 22 of 100 Hz or less, driving There are fewer speed fluctuation components than in the case of <Comparative Example 2> when setting the shaft inertia. Moreover, it can be confirmed that the running is stable.

  Next, FIG. 15 shows W / F (%) of <Comparative Example 1>, <Comparative Example 2>, and <Example 1> for the rotational speed fluctuation component amount (dB) for each frequency of 800 Hz or less in the driven roller 24. ). FIG. 16 shows the effect (dB) of <Example 1> in the driven roller 24 in comparison with <Comparative Example 1>. According to this, the rotational speed fluctuation component of <Example 1> decreases compared to <Comparative Example 1>, a negative region, a positive region when it increases, and 0 if exactly the same. At a frequency of 100 Hz or less, which is considered to be a cause of image defects that are easily noticeable to the human naked eye, the setting of the present invention has a reduced fluctuation component with respect to the initial setting, and the maximum effect is about −21.4 dB at 77 Hz. is there. Further, even in the region of 100 Hz or higher, an effect of about −23 dB is obtained at an average of −10 dB up to the high-frequency measurement limit of 800 Hz, and a maximum of 129 Hz.

  FIG. 17 shows the effect (dB) of the driven roller 24 according to <Example 1> in comparison with <Comparative Example 2>, and the rotational speed fluctuation component of <Example 1> is higher than that of <Comparative Example 2>. It is indicated by a negative region if it decreases, a positive region if it increases, and 0 if it is exactly the same. An increase peak of 6 dB is seen at 200 Hz, but at a frequency of 100 Hz or less, which is considered to be a cause of image defects that are conspicuous with the human eye, the setting of the present invention has a reduced fluctuation component compared to the conventional setting. The maximum effect is about -21.6 dB at 34 Hz.

  From the effect of the driven roller 22 shown in FIG. 16 and FIG. 17, when the inertia 30 is attached to the driven roller 24 as in <Example 1> according to this embodiment, the rotational speed fluctuation component frequency of 100 Hz or less is < There are few rotation fluctuation components compared with the case of any of Comparative Example 1> and <Comparative Example 2>. Moreover, it was confirmed that the rotation was stable.

  FIG. 18 shows the inertia on the same axis as the driven roller 24 as <Example 1> of this embodiment in contrast with <Comparative Example 1> and <Comparative Example 2> at a frequency of 100 Hz or less of the above rotational speed fluctuation component. It is the table | surface which put together the maximum effect at the time of mounting | wearing 30 (dB).

  The effects obtained by <Example 1> of the present embodiment can be summarized as follows.

  1) W / F (%), which is the total amount of fluctuations in the rotational speed of the belt member 22 that carries an image or conveys the sheet P during transfer by electrostatic attraction, was measured. The W / F (%) and the speed fluctuation component amount (dB) up to around 100 Hz, which is considered to be the cause of image defects that are easily noticeable by the human naked eye, indicated by the reference numerals (1) and (2) in the table of FIG. The correlation was considered. According to this, the inertial force of the driven roller 24 is set to be larger than the inertial force of the driving roller 21 among the plurality of rotating rollers. As a result, <comparative example 1> when inertia is set without applying inertial force to both the drive roller 21 and the driven roller 24, and <comparative example 2> when setting drive shaft inertia where inertial force is applied only to the drive roller 21 Compared with>, W / F (%) is smaller than in either case.

  2) Compared to the structure in which an inertia disk or the like is mounted on the driving roller 21 as in the conventional example, in this embodiment, an inertia 30 is mounted on the end of the roller shaft of the driven roller 24, and a plurality of rotating rollers are used. The configuration was changed to the maximum inertia force. By adopting such a configuration, it is possible to provide an image forming apparatus that does not increase the number of parts and the number of assembly steps, is low in cost, and has no image defects.

  3) Further, in the belt drive unit in which the belt member 22 is wound around the driven roller 24 that also serves as a tension bias, the driving roller 21 is dominant over the running speed fluctuation of the belt member 22. Is also a driven roller 24. Therefore, it can be noted that the inertia force of the driven roller 24 is increased or that an inertia increasing means such as the inertia 30 is provided on the driven roller coaxially. From this, even in the current product or the product in which the arrangement configuration of the belt drive unit is completed, if the disturbance of the belt running is given in the drive tension roller group and the roller whose shaft is movably supported can be specified, By fixing the inertia force increasing means coaxially and retrofitting. Greater image stabilization effect than before wearing.

(Second Embodiment)
Next, FIG. 19 shows a structure applied to a belt driving mechanism for a vertical sheet as a second embodiment. Note that the effect of maximizing the amount of inertia with respect to the tension applying driven roller 24 when the speed of the belt member 22 fluctuates while rotating is the same as in the first embodiment.

  In FIG. 19, the sheets P separated and conveyed from the stacked sheet bundle 50 by the sheet feeding unit 1 are aligned by the registration rollers 23, pasted to the electrostatic conveyance belt 22 by the suction roller 17 to which a high voltage is applied, and transferred. It reaches roller 8. The photosensitive drum 3 a in the cartridge 2 a exposed by the scanner unit 9 develops the toner image by the developing sleeve 4 and then transfers the toner to the sheet P on the belt member 22 that is rotationally driven by the driving roller 21. . The sheet P to which the toner image has been transferred is conveyed by the belt member 22 toward the fixing device 11. After separation from the belt member 22 and completion of fixing, the paper discharge roller 12 rotates to discharge the fixed sheet P to the discharge tray 13, and single-sided printing of the sheet P is completed.

  In the case of double-sided printing, the discharge roller 12 does not completely discharge the sheet P, and the discharge roller 12 is reversed while the rear end portion of the sheet P is pinched. As a result, the paper is guided to the double-sided paper refeeding and transporting section 15 and sent to just before the registration roller 23. It becomes a state.

  In FIG. 20 showing an enlarged view of part A in FIG. 19, the driving roller 21 is configured such that the roller shaft end portions 21 a at both ends are freely rotatable in two shaft holes (not shown) provided at both upper ends of the unit frame 61. It is supported. Since the drive roller 21 is only allowed to rotate around the X axis, the degree of freedom in space is “1”. Further, rotational power is transmitted from a rotational drive source (not shown) to one side of the roller shaft end portion 21a, and rotates in the clockwise direction of the arrow in FIG. The peripheral surface portion 21b of the drive roller 21 is provided with means for preventing slippage with the belt member 22 and increasing friction.

  On the other hand, the driven roller A60 is rotatably supported by two shaft holes (not shown) provided at both lower ends of the unit frame 61 with roller shaft end portions 60a at both ends thereof. Therefore, since the driven roller A60 is only allowed to rotate around the X axis, the degree of spatial freedom is “1”. The driven roller B62 is rotatably supported by two shaft holes (not shown) provided at both upper ends of the unit frame 61 with roller shaft end portions 62a at both ends thereof. Accordingly, the degree of freedom of rotation of the driven roller B62 is “1” because only rotation around the X axis is allowed. The driven roller B62 is necessary to secure the width of the belt unit 20 to be equal to or larger than the diameter of the driving roller 21, and the roller shaft end portion 62a is provided with a speed detecting means for the belt member 22, You can also know the running speed.

  The driven roller 24 is for tension application, and the roller shaft end portions 24a at both ends are rotatably supported by the left and right shaft holes 25a via the roller holder 25. The inertia (inertia increasing means) 30 shown in the first embodiment is coaxially provided on at least one end side of the tension applying driven roller 24.

  Holder shaft support holes 25b are provided on both the left and right sides of the roller holder 25, and are swingably supported by the roller holder support shaft 61b of the roller holder support portion 61a installed in the unit frame 61. A belt tension spring 26 is stretched between a tension spring hook 25c of the roller holder 25 and a tension spring hook 61c of the unit frame 61, and the driven roller 24 and the roller holder 25 are referred to in the drawing. It is energizing upward.

  Therefore, in the configuration in which the driven roller 24 is supported, if the driven roller 24 is displaced by D on the circumference of the radius R1 with the shaft center of the roller holder support shaft 61b as the center of oscillation, the displacement D is in the Y-axis direction. Can be divided into Dy and Dz in the Z-axis direction. Accordingly, the driven roller 24 in this case has a spatial degree of freedom of “3” by adding rotation about the X axis. The peripheral surface portion 24b of the driven roller 24 is provided with means for preventing slippage with the belt member 22 and increasing friction.

  In the second embodiment, the driven roller 24 having the largest degree of space freedom among the above four rollers is formed of a relatively heavy specific gravity brass or steel solid shaft, or the inertia 30 is coaxially formed. Provide fixed. Accordingly, if the roller having the largest inertia amount among the four rollers is used, as shown in the table of FIG. 18 as the first embodiment, the drive roller 21 other than the driven roller 24 having its own inertia amount increased. Each W / F (%) of the belt member 22, the driven roller 60, and the driven roller 62 can be reduced.

  The effects obtained in the second embodiment will be summarized below.

  1) The action of maximizing the amount of inertia in the tension applying driven roller 24 with respect to the speed fluctuation component pectram of each shaft and the speed fluctuation component pectram of the belt member 22 is the same as in the case of the first embodiment.

  2) In this way, in the belt drive configuration whose belt drive configuration has already been determined or has already been commercialized as an actual machine, calculate the spatial degree of freedom of the roller that drives and stretches the belt member, Disturb the belt running, identify the driven roller whose shaft is supported movably, install inertia increasing means on the roller, or change to a configuration that has the maximum amount of inertia in the roller group Thus, it is possible to provide an image forming apparatus free from image defects such as Banding without increasing the number of parts, cost, and assembly man-hours.

  In addition, although 1st, 2nd embodiment was described about this invention, it is not limited to those each embodiment, and if it is in the range which does not deviate from the main point of this invention, other embodiment and application Examples, variations, and combinations thereof are possible.

1 is a diagram illustrating an entire image forming apparatus equipped with a belt driving mechanism according to a first embodiment. FIG. The figure which shows the belt drive mechanism of the embodiment. The top view of the belt drive mechanism of the embodiment. The block diagram which shows the structure of the W / F measuring apparatus of the embodiment. The figure which shows <the comparative example 1> at the time of inertia non-setting in the case of not providing an inertia increase means (inertia) in any of a drive roller and a driven roller in the belt drive mechanism of the embodiment. The figure which shows <the comparative example 2> at the time of the drive inertia setting which provided the inertia to the drive roller with respect to the belt drive mechanism of the embodiment. The figure which shows <Example 1> at the time of driven inertia setting in the belt drive mechanism of the embodiment at the time of providing an inertia in a driven roller. The graph which shows the correlation of W / F (%) performance at the time of three types of inertia setting by the said comparative examples 1 and 2 and Example 1. FIG. The graph which shows the correlation of W / F (%) performance at the time of three types of settings, the inertia non-setting in a drive roller, a drive inertia setting, and a driven inertia setting. The graph which shows the effect of W / F (%) performance at the time of inertia non-setting in a drive roller. The graph which shows the effect of W / F (%) performance at the time of the drive inertia setting in a drive roller. The graph which shows the correlation of W / F (%) performance at the time of three types of setting of inertia non-setting, a drive inertia setting, and a driven inertia setting in a belt member. The graph which shows the effect of the W / F (%) performance at the time of inertia non-setting in a belt member. The graph which shows the effect of W / F (%) performance at the time of the drive inertia setting in a belt member. The graph which shows the effect of W / F (%) performance at the time of inertia non-setting in a driven roller. The graph which shows the effect of W / F (%) performance at the time of inertia non-setting in the driven roller which is this embodiment. The graph which shows the effect of W / F (%) performance at the time of the drive inertia setting in a driven roller. The table | surface which shows the maximum effect (dB) of 100 Hz or less in 1st Embodiment for every drive roller, a belt member, and a driven roller. FIG. 5 is a diagram illustrating an entire image forming apparatus equipped with a belt driving mechanism according to a second embodiment. The figure which expands and shows the A section of FIG. 19 in 2nd Embodiment.

Explanation of symbols

3 Photosensitive drum 8 Primary transfer roller 9 Secondary transfer roller
10 Scanner unit 20 Belt drive unit 21 Drive roller (rotating body)
21a Roller shaft end portion 21b Circumferential surface portion 22 Belt member
24 driven roller (rotating body)
24a Roller shaft end portion 24b Circumferential surface portion 25 Roller holder 25a Driven roller shaft hole 25b Roller holder shaft hole 26 Belt tension spring 30 Inertia (Inertia increasing means)
60 Followed roller A
62 Followed roller B

Claims (8)

In an image forming apparatus having an endless belt and a plurality of rotating bodies around which the belt is wound,
An image forming apparatus, wherein one of the plurality of rotating bodies is supported so as to be able to move a position of a rotation axis, and a rotational inertia force is larger and maximum than other rotating bodies.   The image forming apparatus according to claim 1, wherein the rotating body having the maximum rotational inertia force is a driven roller or a non-driven tension roller.   Inertia increasing means for increasing the rotational inertial force, the inertia increasing means being provided coaxially with or parallel to the rotational axis of the driven roller or the non-driven tension roller The image forming apparatus according to claim 2.   The image forming apparatus according to claim 3, wherein the inertia increasing unit is a rotating body or a disk-shaped metal member.   The image according to any one of claims 1 to 4, further comprising friction increasing means for increasing a rotational frictional force with the belt on a peripheral surface of the rotating body having the maximum rotational inertial force. Forming equipment.   The image forming apparatus according to claim 5, wherein the friction increasing unit is provided on the peripheral surface of the rotating body by any one of vulcanization bonding, press-fitting fixing, and adhesive fixing.   The friction increasing means is provided by subjecting the peripheral surface of the rotating body to surface treatment including painting, coating and plating, or any surface roughening treatment including shot peening, sand blasting, uneven processing and microprojection processing. The image forming apparatus according to claim 5, wherein:   The image forming apparatus according to claim 1, wherein the belt is a photosensitive member that carries an image, an intermediate transfer member that carries an image, or a recording material carrier that carries a recording material.

Images