JP6303844B2 - Driving device and image forming apparatus - Google Patents

Description

  The present invention relates to a rotating body driving device for driving a rotating body such as a photosensitive drum or a roller in an image forming apparatus, and an image forming apparatus including the rotating body, and more particularly to a motion that suppresses fluctuations in rotational speed of the rotating body. The present invention relates to a drive device having a vibration absorber and an image forming apparatus including the drive device.

  Conventionally, in an image forming apparatus, when the rotational speed of the photosensitive drum varies, the scanning pitch in the sub-scanning direction changes, and density unevenness in the sub-scanning direction, that is, so-called banding occurs on the image. In order to reduce such banding, a configuration in which a flywheel is provided on the same axis as the photosensitive drum is employed. However, this configuration increases the size and weight of the device in order to suppress speed fluctuations by increasing the diameter of the flywheel.

  In order to solve this problem, a configuration is known in which a dynamic vibration absorber having a small-diameter inertia body is provided that suppresses fluctuations in the rotational speed of the photosensitive drum without increasing the size of the flywheel (see, for example, Patent Document 1). ). The apparatus described in Patent Document 1 is configured to include a dynamic vibration absorber in which an annular inertia member is provided on the outer periphery of a drive shaft that rotates integrally with the photosensitive drum via an annular rubber material. This configuration is a dynamic vibration absorber configuration in which a viscoelastic rubber material serves as both a spring element and a viscous element. Since the viscoelastic characteristics of rubber materials change greatly with the environmental temperature, the effect of the dynamic vibration absorber is significantly reduced when the environmental temperature changes. Moreover, in a temperature range such as a low temperature, there is a possibility of causing a side effect of increasing vibration.

  Further, in the transfer device in the image forming apparatus, when the secondary transfer roller is used as the second transfer device that transfers the toner image on the intermediate transfer belt to the sheet, the secondary transfer roller passes through the intermediate transfer belt. Thus, it is configured to press against the opposing roller. For this reason, when the sheet enters the secondary transfer unit, the conveyance speed of the intermediate transfer belt may fluctuate, and transfer blur may occur in the primary transfer unit that comes into contact with the photosensitive drum. In addition, there is a problem that shock jitter that disturbs the image occurs.

  In order to solve such a problem, a method of attaching a flywheel having a large inertia to the suspension roller of the intermediate transfer belt has been proposed (see, for example, Patent Document 2). The device described in Patent Document 2 is a dynamic vibration absorber having a configuration in which an elastic body is sandwiched between rotating bodies and an inertial body is provided. If the elastic body is made of a rubber material in the same manner as the apparatus of Patent Document 1, the effect of the dynamic vibration absorber is significantly reduced when the environmental temperature changes.

  As a result of intensive research on the speed fluctuation of the intermediate transfer belt caused by the entrance of paper, the mechanism was elucidated as follows. When the paper enters the pressing portion of the secondary transfer roller and the opposing roller, the pressing force increases, and the corresponding load torque is generated in the intermediate transfer belt, resulting in speed fluctuation. This speed fluctuation is oscillated and attenuated at a certain frequency. The inventor of the present application measured the frequency response characteristics between the motor as the driving source of the intermediate transfer belt and the driven roller, and the resonance frequency at that time coincided with the speed fluctuation frequency of the intermediate transfer belt generated when the paper entered. I found out.

  The inventor of the present application has found that if the gain at the resonance point of the frequency response characteristic between the drive motor and the driven roller is reduced, the speed fluctuation generated in the intermediate transfer belt can be suppressed. As a result of experiments using a dynamic vibration absorber as a means for reducing the resonance gain, it was found that speed fluctuations occurring in the intermediate transfer belt can be suppressed.

  FIG. 10 shows the result of evaluation of the frequency response characteristics between the drive motor for driving the intermediate transfer belt and the driven roller by the inventor of the present application changing the environmental temperature of the dynamic vibration absorber. As can be seen from this figure, the temperature characteristics were evaluated by setting the optimum condition of the dynamic vibration absorber at room temperature. At room temperature, the resonance point gain is nearly flat. If it becomes such a characteristic, the function of a dynamic vibration absorber can be exhibited to the maximum, and a vibration can be suppressed. In addition, the resonance point does not shift in a high temperature environment, but the gain is larger than that at room temperature. However, although it is smaller than the default condition in which no dynamic vibration absorber is applied, the vibration suppression effect is reduced.

  On the other hand, it has been found that the resonance point shifts to a lower side in a low temperature environment, and the gain is considerably larger than that at room temperature. In such a frequency response characteristic, the vibration itself is the same as the default without a dynamic vibration absorber, even if the generated vibration is shifted to the low frequency side. Further, the drive system of the intermediate transfer belt is controlled by a control system based on information from a sensor attached to the driven roller and the belt in order to convey the belt with high accuracy. However, if the resonance point becomes lower in a low temperature environment than the default state where no dynamic vibration absorber is applied, control is performed with a control system that takes this into consideration, which causes a problem that the control performance is greatly reduced.

  In view of this, the present inventor has proposed that a dynamic vibration absorber using a viscoelastic rubber material is provided with a Peltier element having heating and cooling functions and temperature controlled to a target temperature. However, controlling to the target temperature with heating and cooling functions is complicated and expensive.

  As described above, in the configuration of the rotary type dynamic vibration absorber, a viscous element (actually a viscoelastic element whose viscosity is dominant) is incorporated therein. Typical examples of viscosity generation include those using rubber materials and those using oil. However, due to the influence of temperature change, the viscosity becomes high at low temperatures and, conversely, the viscosity becomes low at high temperatures, so that there is a large difference in vibration absorption characteristics. Therefore, the operating temperature range where the effect is exhibited is greatly limited. Although improved by the development of new materials, it is difficult to secure a material that maintains a stable viscosity in a wide band from low to high temperatures.

  On the other hand, the internal temperature of printers that use photoconductor drums and intermediate transfer belts is 0 ° C to 40 ° C, and may be in a wide range of -5 ° C to 60 ° C, depending on fluctuations in the external temperature corresponding to the room temperature. There is. In order to minimize the rotational fluctuation and obtain a high-quality print quality, it is necessary to obtain a stable viscoelastic property that is not affected even within this temperature range. However, in reality, there is no material that can ensure stable characteristics in such an environment. For this reason, the actual configuration and use have been devised such that the use is limited within an environmental temperature where characteristics can be obtained, or the type of viscous material to be used is changed according to the temperature change.

  The present invention has been made in view of the above problems, and the performance of a dynamic vibration absorber applied to a rotating body drive device and a photosensitive drum drive or an intermediate transfer belt drive of an image forming apparatus is affected by the environmental temperature. The object is to provide a simple and inexpensive configuration that can be used without any problems.

  A rotating body drive device according to the present invention includes a dynamic vibration absorber having at least a spring element, a viscous element, and an inertia element on a rotating shaft. The spring element and viscous element are set so that the dynamic vibration absorber becomes the optimum condition at the maximum temperature condition in the drive device that is assumed for the side limit operating environment temperature, and any environmental condition that the drive device is determined by the specifications The dynamic vibration absorber is always temperature controlled to the target temperature at the maximum temperature condition even when used in the above.

  According to the present invention, if the dynamic vibration absorber is designed under the optimum conditions under the assumed maximum temperature condition, it is possible to turn on the control that increases the temperature in one direction and off the control that does not increase the temperature any more in any use environment. It becomes. And it is realizable with the simple and cheap structure by control of a heater etc. That is, complicated and expensive temperature control combining a heater and a cooling device for controlling the target temperature is not necessary.

1 is a schematic configuration diagram of an entire image forming unit in a copier that is an object of the present invention. It is a figure which shows the example which attached the dynamic vibration absorber to the driven roller shaft. It is a figure which shows embodiment which applied the dynamic vibration absorber which concerns on this invention to the drive system of the photosensitive drum. It is a figure which shows the example of the dynamic vibration damper which concerns on embodiment of this invention. It is a perspective view which shows the example of an inertial body. It is sectional drawing which shows embodiment from which the structure of a dynamic vibration absorber differs. It is a figure which shows a frequency response characteristic when setting a dynamic vibration absorber to become an optimal condition in a high temperature state. It is a figure which shows the data which measured the speed fluctuation before and behind when a paper approachs a secondary transfer part. It is a figure which shows the speed fluctuation | variation data when a dynamic vibration damper is provided to a driven roller. It is a figure which shows the result of having evaluated the frequency response characteristic between the drive motor of an intermediate transfer belt drive, and a driven roller by shaking the environmental temperature of a dynamic vibration absorber.

  Hereinafter, the present invention will be described based on an embodiment in which the present invention is applied to an electrophotographic color copier (hereinafter referred to as “copier”) which is an image forming apparatus. Note that the copying machine according to the present embodiment is a so-called tandem image forming apparatus that employs a dry two-component development system using a dry two-component developer.

<Embodiment 1>
FIG. 1 is a schematic configuration diagram of the entire image forming unit in the copying machine according to the present embodiment. This copying machine receives image data as image information from an image reading unit (not shown) and performs image forming processing. As shown in FIG. 1, this copying machine is abbreviated as yellow (hereinafter abbreviated as “Y”), magenta (hereinafter abbreviated as “M”), and cyan (hereinafter abbreviated as “C”). ), Black (hereinafter abbreviated as “Bk”), photosensitive drums 1Y, 1M, 1C, and 1Bk, which are latent image carriers as four rotating bodies for each color, are arranged in parallel. These photosensitive drums 1Y to 1Bk are arranged side by side along the belt moving direction so as to contact the endless belt-shaped intermediate transfer belt 5 supported by a plurality of rotatable rollers including a driving roller. . Further, around the photosensitive drums 1Y to 1Bk, the chargers 2Y, 2M, 2C, and 2Bk, the developing devices 9Y, 9M, 9C, and 9Bk corresponding to the respective colors, the cleaning devices 4Y, 4M, 4C, and 4Bk, the static elimination lamp, respectively. Electrophotographic process members such as 3Y, 3M, 3C, and 3Bk are arranged in the order of processes.

  A case where a full-color image is formed by the copying machine according to the present embodiment will be described. First, the photoreceptor drum 1Y is uniformly charged by the charger 2Y while being driven to rotate in the direction of the arrow by a photoreceptor drive device (not shown), and then a light beam LY from an optical writing device (not shown) is emitted. Irradiation forms a Y electrostatic latent image on the photoreceptor drum 1Y. This Y electrostatic latent image is developed with Y toner in the developer by the developing device 9Y. During development, a predetermined developing bias is applied between the developing roller and the photosensitive drum 1Y, and the Y toner on the developing roller is electrostatically attracted to the Y electrostatic latent image portion on the photosensitive drum 1Y.

  The Y toner image developed and formed in this way is conveyed to a primary transfer position where the photosensitive drum 1Y and the intermediate transfer belt 5 come into contact with the rotation of the photosensitive drum 1Y. At this primary transfer position, a predetermined bias voltage is applied to the back surface of the intermediate transfer belt 5 by the primary transfer roller 6Y. The Y toner image on the photosensitive drum 1Y is drawn toward the intermediate transfer belt 5 by the primary transfer electric field generated by the bias application, and is primarily transferred onto the intermediate transfer belt 5. Thereafter, similarly, the M toner image, the C toner image, and the Bk toner image are also primarily transferred so as to sequentially overlap the Y toner image on the intermediate transfer belt 5. In FIG. 1, reference numerals 5a to 5f denote rollers (including a driving roller, a driven roller, a tension roller, and a counter roller of a registration roller described later) that are wound around the intermediate transfer belt 5.

  As described above, the toner images having the four colors superimposed on the intermediate transfer belt 5 are conveyed to the secondary transfer position facing the secondary transfer roller 7 as the intermediate transfer belt 5 rotates. Further, the transfer paper P (simply indicated by an arrow in the drawing) is conveyed to the secondary transfer position by the registration roller 10 at a predetermined timing. Then, at this secondary transfer position, a predetermined bias voltage is applied to the back surface of the transfer paper P by the secondary transfer roller 7. The toner image on the intermediate transfer belt 5 is secondarily transferred onto the transfer paper P collectively by the secondary transfer electric field generated by the bias application and the contact pressure at the secondary transfer position. Thereafter, the transfer paper P onto which the toner image has been secondarily transferred is subjected to fixing processing by the fixing roller pair 8 and then discharged outside the apparatus.

  FIG. 2 shows an example in which the dynamic vibration absorber is attached to the driven roller shaft. The driving roller 11 is connected to the driving roller shaft 11 a from the motor 25 through the speed reducer 26 and is rotated by driving of the motor 25. The intermediate transfer belt 5 is conveyed in the direction of the arrow by the rotation of the driving roller 11. The rollers and the like that are wound around the intermediate transfer belt 5 are an entrance roller 16, a counter roller 15, a tension roller 14, and driven rollers 12 and 13 from the upstream side in the conveyance movement direction of the intermediate transfer belt 5. All the rollers other than the drive roller 11 are driven rollers that rotate along with the movement of the intermediate transfer belt 5. Among them, a roller having an engagement angle of 90 ° or more with the intermediate transfer belt 5 is a counter roller 15 and a driven roller 13. In the example of FIG. 2, the dynamic vibration absorber 20 is attached to the shaft 13 a of the driven roller 13 via the coupling body 22. However, the dynamic vibration absorber 20 may be attached by the opposing roller 15 or the tension roller 14. However, since the sliding between the intermediate transfer belt 5 and each roller can be suppressed when the angle of the intermediate transfer belt 5 is large, the driven roller 13 or the counter roller 15 is preferable as a roller to which the dynamic vibration absorber 20 is attached. I can say that. Furthermore, since the driven roller 13 is provided in the vicinity on the upstream side of the photosensitive drum 1, the effect of the dynamic vibration absorber 20 can be further exhibited.

  FIG. 3 is a view showing an embodiment in which the dynamic vibration absorber according to the present invention is applied to a drive system of a photosensitive drum. Photosensitive drums 1Y, 1M, 1C, and 1Bk (hereinafter denoted by 1) are attached to the drum shaft 1a so as to rotate integrally. The drum shaft 1a is bridged between a main body front side plate 1c and a main body rear side plate 1d constituting the apparatus main body via a bearing 1b, and is rotatably supported. The drum shaft 1a is provided so as to protrude to the outside of the main body rear side plate 1d. A drive gear 1e constituting the drive system of the photosensitive drum 1 is attached so as to rotate integrally. The drive gear 1e meshes with a motor gear 1h fixed to the motor shaft 1g of the drive motor 1f, so that the rotation of the drive motor 1f is transmitted and the photosensitive drum 1 rotates. Further, a dynamic vibration absorber 20 is attached to an end portion of the drum shaft 1a extending outside the drive gear 1e (a side away from the main body rear side plate 1d).

  The dynamic vibration absorber will be described. The dynamic vibration absorber is composed of a small inertia body (a metal inertia plate in this embodiment), a driven roller shaft, and a connecting body that connects the inertia body. The design parameters for designing the dynamic vibration absorber are three parameters: the inertia moment of the inertial body, the spring constant of the coupled body, and the viscous damping coefficient. As a design procedure, first determine the size and moment of inertia of the inertia body from specifications such as the size, weight and load torque of the device, and then from the motor that drives and conveys the intermediate transfer belt to the drive transmission system, the intermediate transfer belt, and The spring constant and viscous damping coefficient of the connection band of the dynamic vibration absorber are designed from the physical parameters of each stretched roller. The spring constant of this coupling body is about 1/10 to 1/1000 times the rigidity of the driven roller shaft when mounting a flywheel as in the conventional example, although it depends on the inertial moment of the inertial body to be set. become. On the contrary, the viscosity damping coefficient is set to a viscosity of about 10 to 1000 times. As a specific material, it is embodied by using a resin, rubber, a thin metal rod, or a hybrid configuration thereof.

A specific example of the dynamic vibration absorber as described above will be described with reference to FIGS.
FIG. 4 shows an example of application to the intermediate transfer belt 5 shown in FIG. 2, and the dynamic vibration absorber 20 is composed of a rubber member (viscous function member) and a metal bar spring. (Spring functional member). The spring constant of the dynamic vibration absorber 20 can be adjusted according to the rigidity of the rubber and the diameter, length, and number of the bar spring, and can be adjusted to the design value. The viscosity can be adjusted by the physical properties blended in the rubber.

First, a bar spring which is a spring functional member or a spring element will be described.
The bar spring 111 has a boss part 114 having a hole through which the rotation shaft passes in the center part, a plurality of spokes 115 in which the outer periphery of the boss part 114 is evenly arranged and radially extending, and an inertial body and a contact surface on the outer periphery. It consists of an outer ring part that is fixed. The bar spring 111 is fixed to the rotating shaft 113 with a boss portion 114. An appropriate method may be adopted as the fixing method. For example, it is possible to employ screw fixing, a method of engaging the shaft and the hole with a D-shape, or a rotation prevention with an oval engagement. Of course, other methods may be used.

  The material of the bar spring 111 can be made of metal, but the spoke 115 becomes long in order to obtain a desired spring constant. Therefore, since the shape becomes large, it is desirable that the resin is made of a resin having rigidity lower than that of metal. For example, polyacetal, polycarbonate, ABS or the like is preferable as the material. When a small spring constant is easily set for a resin having a small rigidity and a large rigidity is required, the setting can be performed by increasing the number of the spokes 115 or increasing the cross-sectional area. Furthermore, by using resin, mass production is possible by injection molding, productivity is improved, and production can be made at low cost.

  Next, the rubber member which is a viscous function member will be described. The rubber member 112 has a cylindrical shape, but is not limited to this shape. The material is preferably made of viscoelastic rubber. For example, rubber materials such as NBR, EPDM, and NR can be employed.

  Both end surfaces of the rubber member 112 are flat, one is bonded concentrically with the inertial body 110 and the other is bonded with a surface concentric with the support member fixed to the rotating shaft 113. Adhesion is preferably a rubber-based double-sided adhesive tape considering assembly. Alternatively, the support member may be manufactured by vulcanization bonding when processing rubber, and the inertia member may be bonded to the double-sided tape.

  The supporting member is provided with the boss 114 fixed to the rotation shaft, the flange 118 bonded to the rubber member 112, and the end surface of the flange 118 so as to be fitted to the inner diameter of the rubber member 112. It consists of an annular protrusion. When the protrusion and the rubber member 112 are fitted, the concentric accuracy with the rotating shaft 113 is increased, and the rotation fluctuation can be suppressed.

Next, an example of controlling the temperature by surrounding the dynamic vibration absorber will be described with reference to FIG.
In this example, the entire dynamic vibration absorber is covered with a heat insulating cover (case 120) and has a sealed structure so as not to be affected as much as possible by the external temperature (inside the main body device and outside room environment temperature). It is sufficient that the temperature of the portion where the rubber member 112, which is a viscoelastic member, is at least constant.

  In order to keep the temperature inside the case 120 constant, a structure that is not affected by the outside air temperature inside or in addition to the inside of the apparatus is adopted. The heat insulating cover body constituting the case 120 is formed by drawing a resin molded product or metal, taking into account the weight reduction and cost reduction of the device, and the heat insulating material is pasted on the inside to thermally Increase the blocking effect.

  The case 120 preferably has a split shape that can be divided with respect to the rotating shaft portion (rotating shaft 113) of the apparatus in order to improve assemblability and maintainability. This is illustrated as “division positions” in FIGS. 4 and 5. This makes it possible to attach and detach. The case 120 is fixed to the main body side plate (unit frame 130 in the illustrated example) by a screwing portion 122 formed outside. Of course, other fixing methods can be employed.

  As the heat insulating material 121, a sheet-like material such as foamable rubber, foamed plastic, felt, or glass wool may be attached. Both may be fixed by a click method using a claw method or a screw method.

  In order to minimize the entry and exit of air in the vicinity of the rotating shaft 113, a seal material 116 made of a material such as a Teflon (registered trademark) film having a low contact resistance or a nonwoven fabric is applied. The sealed case 120 is provided with a heater 117 for increasing or decreasing the internal temperature. A cooler may be provided.

  As the heater 117 for raising the temperature, it is preferable to use a ceramic heater or a sheet heating element (sheet heater, film heater, etc.) that can be formed compactly. Regarding the setting position, the heater 117 is not particularly limited. However, when the heater 117 is provided so as to be positioned below the case 120, a temperature rising effect due to natural convection of the air in the case 120 can be expected.

  Further, a temperature sensor S1 is attached and fixed inside the case 120, and the heater 117 is energized based on the detected temperature. A platinum film temperature sensor or the like can be selected as the temperature sensor S1. When the operating environment temperature range of the apparatus is standardized from 5 ° C. to 32 ° C., the temperature rise inside the case 120 is about 15 ° C. plus the outside temperature. Therefore, assuming that the maximum temperature limit of the internal temperature of the device is 47 ° C, the case internal temperature target value surrounding the dynamic vibration absorber is set to 45 ° C, and the temperature in the region of 45 ° C ± 2 ° C is taken into account when temperature control variation is considered. It is preferable to control.

  If the temperature sensor S1 detects 45 ° C. or lower, the heater 117 is energized to operate and the temperature rise is continued. When the detected temperature reaches 45 ° C., power supply is stopped once. The temperature rises slightly due to thermal inertia but then decreases. Thereafter, the temperature detection value of 45 ° C. is set as a threshold level, and the temperature inside the cover body is maintained while turning on and off repeatedly.

  The temperature control controller 140 includes a CPU 141, a temperature controller 142, a comparator 143, and a heating driver 144.

  Temperature control is performed as follows. The temperature inside the case 120 is detected by the temperature sensor S1, and a data signal of the temperature is output to the comparator 143. The output temperature is compared with the target temperature 45 ° C. stored in the CPU 141, and if the internal temperature of the case 120 is lower than 45 ° C., the heater 117 for heating is driven from the temperature controller 142 by the heating driver 144. The inside of the case 120 is heated. Heating is continued and the heater 117 is driven until the temperature sensor S1 detects 45 ° C. When the data signal of the temperature sensor S1 output to the comparator 143 reaches 45 ° C., the heating driver 144 is stopped. Thereafter, when the data signal of the temperature sensor S1 falls below 45 ° C., the heating driver 144 is driven again. By repeating this, the temperature inside the case is controlled to around 45 ° C.

  FIG. 5 is a cross-sectional view showing a dynamic vibration absorber 200 having a different configuration. The example of FIG. 4 has the same configuration except for the dynamic vibration absorber. In addition, the components of the dynamic vibration absorber 200 that are the same as those of the dynamic vibration absorber 20 in the example of FIG. For example, a spring member corresponding to the bar spring 111 which is a spring element is denoted by reference numeral 111a.

  The inertial body 110a is fixed to the outer ring portion of the bar spring 111a with a screw 119, and is supported in a float state that does not directly contact the rotating shaft 113. The weight and inertia of the inertial body 110 are received by the spoke 115, and the spring function of the spoke 115 is exhibited against rotation and vibration. The spoke 115 is preferably configured so as to have a step with the outer ring portion of the bar spring 111a so as not to contact the inertial body 110a. By doing so, there is no hindrance to the movement of the spring function due to the contact with the inertial body 110a (the movement for absorbing vibration in the rotation direction of the inertial body 110a), so that the spring function is more accurately exhibited.

  Although the number of the spokes 115 is shown as four in the illustrated embodiment, it is desirable that three or more spokes 115 are arranged uniformly (arranged at equal angular intervals) in the radial direction. If the number of spokes 115 is two or less, under the condition that the spring constant is small to support the weight of the inertial body 110a, there is a possibility that the rotation will fluctuate due to deflection or the like when the spoke 115 is positioned in the horizontal direction.

  FIG. 7 shows frequency response characteristics when the dynamic vibration absorber is set to be in an optimum condition in a high temperature state. The gain peak value at the resonance point is increased in the default configuration without a dynamic vibration absorber, whereas the gain peak value is set substantially flat near the resonance point in a high temperature environment and greatly reduced. If the dynamic vibration absorber can be set so as to exhibit such characteristics, the vibration can be stably reduced if the dynamic vibration absorber is always temperature-controlled in a high temperature region (for example, 45 ° C. ± 2 ° C.). Incidentally, when the optimum condition is set in the high temperature region, the frequency response characteristic is as shown by the dotted line at room temperature, and the characteristic has a resonance point peak slightly on the low frequency side. Conversely, by setting such characteristics at room temperature, optimum conditions are set in a high temperature region.

An example of the effect when a dynamic vibration absorber is added to the intermediate transfer belt unit will be described.
FIG. 8 shows data obtained by measuring the speed fluctuation before and after the paper enters the secondary transfer portion. When the paper enters the secondary transfer portion, a large speed fluctuation occurs as indicated by the data. The fluctuation period at that time coincides with the frequency of the resonance point shown in FIG. FIG. 9 shows a speed fluctuation data when a dynamic vibration absorber is applied to the driven roller. The dynamic vibration absorber at this time is set so as to exhibit a frequency response characteristic in which the gain at the peak of the resonance point shown in FIG. By setting in this way, it is possible to reduce the speed fluctuation (shock jitter) when entering the paper.

  The present invention is not limited to the embodiments described above, and many variations are possible by those having ordinary knowledge in the art within the technical idea of the present invention.

1: Photosensitive drum 1a: Drum shaft 1b: Bearing 1c: Main body front side plate 1d: Main body rear side plate 1e: Drive gear 1f: Drive motor 1g: Motor shaft 1h: Motor gear 2: Charger 3: Charger lamp 4: Cleaning device 5 : Intermediate transfer belt 6: Primary transfer roller 7: Secondary transfer roller 8: Fixing roller pair 9: Developing device 10: Registration roller 11: Drive roller 11a: Drive roller shaft 12: Drive roller 13: Drive roller 13a: Drive roller shaft 14: tension roller 15: counter roller 16: entrance roller 20: dynamic vibration absorber 22: coupling body 25: motor 26: speed reducers 110, 110a: inertial bodies 111, 111a: bar spring 112: rubber member 113: rotating shaft 114: Boss part 115: Spoke 116: Sealing material 117: Heater 118: Flange part 119: Screw 1 20: Case 121: Insulating material 122: Screwing part 130: Unit frame 140: Control part 142: Temperature controller 143: Comparator 144: Heating driver 200: Dynamic vibration absorber LY: Light beam P: Transfer paper
S1: Temperature sensor

JP-A-8-146824 JP2000-240724 JP 4-120582

Claims (6)

In a drive device for a rotating body including a dynamic vibration absorber having at least a spring element, a viscous element, and an inertia element on a rotating shaft
The spring element and the viscous element are set so that the dynamic vibration absorber becomes the optimum condition at the highest temperature condition in the drive unit that is assumed for the high temperature side limit use environment temperature determined by the specifications of the drive unit of the rotating body. ,
Regardless of the environmental conditions determined by the specifications of the drive unit, the temperature of the dynamic vibration absorber is always controlled with the above maximum temperature condition as the target temperature.
A drive device for a rotating body. The drive device according to claim 1,
Covering at least a portion where the viscous element is disposed with a cover having a thermal barrier effect with outside air;
The cover is provided with a heater capable of raising the internal temperature of the cover to a target temperature, and a temperature sensor for detecting the internal temperature of the cover,
An apparatus for driving a rotating body, wherein the heater is operated to control the internal temperature of the cover to a target temperature based on a detection value of the temperature sensor. The drive device according to claim 1 or 2,
A rotating body drive device characterized in that the viscous element of the dynamic vibration absorber is made of viscoelastic rubber.   An image forming apparatus comprising the rotating body drive device according to claim 1.   5. The image forming apparatus according to claim 4, wherein the dynamic vibration absorber is attached to a shaft of a photosensitive drum. 6. The image forming apparatus according to claim 5, wherein the dynamic vibration absorber is attached to a roller that stretches the intermediate transfer belt in the intermediate transfer belt unit.