JP2003172402A - Rotary driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To securely reduce fluctuation of speed of a rotary body by dynamic damper effect while making it realized to arrange a light and miniaturized dynamic damper in a small mounting space. <P>SOLUTION: A gear inertia body 30 is rotatably arranged on a fixed shaft 22a of a second gear row 22. Moreover, a gear damper 32 is coaxially fixed on a rotary shaft 26 of the rotary body 14 and is meshed with the gear inertia body 30. Absorption frequency f of the dynamic damper composed of the gear inertia body 30 and the gear damper 32 is set in such a way that it agrees with a meshing frequency of a transmission gear row 12 of a main vibration system which is one of vibration components generated in a drive system and the second gear row 22. The number of teeth of the gear inertia body 30 is set to be smaller than that of the gear damper 32, and the gear inertia body 30 acceleratively rotates relative to the rotation of the gear damper 32. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary drive device for transmitting a rotary drive force of a drive source to a rotating body through a gear train as a drive transmission system, and more particularly to an electrophotographic laser printer and a copying machine. The present invention relates to a rotation drive device suitable for an image forming apparatus such as a facsimile.

[0002]

2. Description of the Related Art A rotary drive unit mounted on an image forming apparatus is a photosensitive drum, which is a rotating body, a drive motor, which is a drive source, and a drum of the photosensitive drum, which receives the rotational force of the drive motor via a drive shaft. And a drive transmission system for transmitting to the shaft. The drive transmission system is composed of a gear train, and a plurality of intermediate gears are arranged in mesh with each other between a motor gear fixed to the output shaft of the drive motor and an output gear fixed to the drum shaft.

In such a rotary drive device, the rotational speed fluctuation of the frequency due to the meshing of the intermediate gears of the drive transmission system, the rotational frequency of the drive motor gear or the intermediate gear, the switching frequency of the excitation of the drive motor, etc. As a result, speed fluctuations occur. When speed fluctuations occur on the surface of the photoconductor drum due to these factors, the image becomes light and shade at regular intervals, and uneven density occurs. As a technique for avoiding the speed fluctuation of the photosensitive drum, for example, a technique described in Japanese Patent Laid-Open No. 2001-188438 is known.

As shown in FIG. 14, the rotary drive device disclosed in JP 2001-188438 A has a drive motor 1 and a drive motor 1 as shown in FIG.
Gear train (comprising a motor gear of the drive motor 1, a plurality of intermediate gears, and gears fixed to the drum shaft) 2, a photoconductor drum 3, and a drum shaft integrally provided on the photoconductor drum 3. 4, a flywheel 5 attached to the end of the drum shaft 4. In addition, the photosensitive drum 3
Ring-shaped inertial body 6 having a moment of inertia on the outer periphery of
However, the inertia body 6 and the elastic body 7 function as a dynamic damper.

Then, when the torque of the drive motor 1 that rotates according to a command from the drive control device is transmitted to the drum shaft 4 through the gear train 2 and the drum shaft 4 and the photoconductor drum 3 rotate, the photosensitive drum of the main vibration system is exposed. With respect to the body drum 3, the effect of reducing the vibration to the specific frequency by the dynamic damper is obtained, and the speed fluctuation of the photoconductor drum 3 is reduced. Further, Japanese Patent Laid-Open No. 2001-188438 also shows an embodiment in which a ring-shaped inertial body 6 is attached to the outer periphery of the flywheel 5 via an elastic body 7, as shown in FIG. By adding a dynamic damper composed of the inertial body 6 and the elastic body 7 to the flywheel 5, the vibration suppressing effect of the flywheel 5 and the vibration reducing effect to a specific frequency by the dynamic damper can be obtained. The speed fluctuation of 3 is reduced.

[0006]

However, the above-mentioned Japanese Unexamined Patent Application Publication
In the technique described in 2001-188438, a dynamic damper including a large-diameter inertia body 6 and the elastic body 7 is arranged on the outer circumference of the photosensitive drum 3 (FIG. 14), or on the outer circumference of the flywheel 5. Since a dynamic damper composed of a large-diameter inertial body 6 and an elastic body is arranged (Fig. 15) and the volume and weight are increased, a wide mounting space for mounting the dynamic damper is required. At the same time, the present situation is that the rotation drive device is significantly increased in weight and size.

The present invention has been made in view of the above circumstances, and it is possible to arrange a dynamic damper, which is small and lightweight, in a small mounting space, and surely reduces the speed fluctuation of the rotating body by the dynamic damper effect. It is an object of the present invention to provide a rotation drive device that can be used.

[0008]

In order to achieve the above object, a rotary drive device according to a first aspect of the present invention includes a rotary body, a drive shaft fixed to the rotary body, and a transmission gear train. In a rotary drive device including a drive motor drivingly connected to the drive shaft, an inertial body is rotatably arranged on a predetermined fixed shaft forming the transmission gear train, and the rotary shaft is rotated on the drive shaft. A damper rotating body having a diameter equal to or smaller than the outer diameter of the body is coaxially fixed, and the rotation of the drive shaft is transmitted to the inertial body via the damper rotating body to constitute a dynamic damper.

According to a second aspect of the present invention, in the rotary drive device according to the first aspect, the vibration absorption frequency of the dynamic damper, the meshing frequency of the transmission gear train, the rotation frequency of the drive motor, the transmission gear. Row rotation frequency,
It is matched with one of the excitation switching frequencies of the drive motor. According to a third aspect of the present invention, in the rotary drive device according to the first or second aspect, the inertia body is a gear inertia body having teeth on its outer circumference, and the damper rotor is provided with teeth on its outer circumference. The gear damper meshes with the gear inertial body.

According to a fourth aspect of the present invention, in the rotary drive unit according to the third aspect, the teeth of the transmission gear fixed to the drive shaft of the transmission gear train and the teeth of the gear damper are circumferentially arranged. By shifting by half a pitch in the direction, a frequency component matching the meshing frequency of the transmission gear train and having a phase shifted by a half cycle is generated. According to a fifth aspect of the present invention, in the rotary drive device according to the first or second aspect, the inertial body is a pulley inertial body provided with a belt engaging surface on the outer circumference, and the damper rotating body is provided on the outer circumference with a belt. A pulley damper having an engaging surface is provided, and a rotation transmission belt is stretched between the pulley inertial body and the pulley damper.

According to a sixth aspect of the present invention, in the rotary drive device according to any of the first to fifth aspects, the rotation of the damper rotating body is accelerated and transmitted to the inertial body. Furthermore, the invention according to claim 7 is the invention according to claims 1 to 6.
In the rotary drive device according to any one of the above items, the inner diameter portion of the damper rotation body is fixed to the drive shaft via an annular elastic body.

[0012]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, before describing the embodiment of the present invention, a schematic configuration diagram of a conventional rotary drive device related to the present invention is shown in FIG. The rotary drive device shown in FIG. 12 includes a drive motor 10, a transmission gear train 12, and a rotating body 1.
4 is provided with a rotating body side gear 16, and the drive motor 10 is a motor gear 18 that meshes with the transmission gear train 12.
Is equipped with.

The transmission gear train 12 is composed of a first gear train 20 and a second gear train 22 arranged between the motor gear 18 and the rotor side gear 16. The first gear train 20 is a first gear wheel 20 rotatably arranged on a fixed shaft 20a.
b, the first small gear 20c, the first large gear 20b meshes with the motor gear 18, and the first small gear 20c meshes with the second gear train 22. The second gear train 22 is a second gear train that is rotatably arranged on the fixed shaft 22a.
It is composed of a large gear 22b and a second small gear 22c,
The second large gear 22b is the first small gear 20c of the first gear train 20.
And the second pinion gear 22c is engaged with the rotor side gear 1
6 is engaged. Further, the rotary body side gear 16 is coaxially fixed to the rotary shaft 26 together with the rotary body 14. The fixed shafts 20a and 22a are fixed to the device case 24, and the rotary shaft 26 is rotatably supported by the device case 24.

In the rotary drive device shown in FIG. 12, when torque is generated by driving the drive motor 10 according to a command from a drive control device (not shown), the motor gear 18 and the transmission gear train 12 are provided.
The rotation is transmitted to the rotary shaft 26 via the gear 16 on the rotary body side, and the rotary body 14 is rotated. The drive system composed of the drive motor 10, the transmission gear train 12, and the rotating body 14 has a natural frequency of torsional vibration in the rotation direction, and whether this frequency matches the frequency of the drive system serving as the vibration source. , Or when both approach each other, resonance occurs and the speed fluctuation increases.

That is, FIG. 13 shows speed fluctuations of the rotary drive device shown in FIG. The thick solid line in this figure represents the power spectrum of the speed fluctuation. As the vibration component generated in the drive system, the meshing frequency of the first gear train 20 and the second gear train 22 is 215 Hz, and the second gear train 22 is
There are peaks of speed fluctuations such as a meshing frequency of 55 Hz between the gear 16 and the rotor-side gear 16, a rotation frequency of the drive motor 10 of 24 Hz, and a rotation frequency of the first gear train 20 of 12 Hz.
Also, the thin solid line in this figure represents the frequency response (transmission gain) of the drive system, and one of the natural frequencies is 215 Hz.
It is in. Therefore, the first gear train 20 and the second gear train 22
The meshing frequency with and the natural frequency of the drive system match 2
At 15 Hz, resonance occurs and the speed fluctuation increases.

Next, FIG. 1 shows a schematic configuration of a rotary drive device of a first embodiment according to the present invention. The same components as those shown in FIG. 12 will be assigned the same reference numerals and explanations thereof will be omitted. In the present embodiment, an inertial body (hereinafter referred to as a gear inertial body) 30 composed of a gear is rotatably arranged on a fixed shaft 22a constituting the second gear train 22, and a rotary shaft 26 of the rotary body 14 is provided. Further, a damper rotating body (hereinafter referred to as a gear damper) 32 composed of a gear is coaxially fixed and meshed with the gear inertia body 30. The gear inertial body 3
Reference numeral 0 is a small gear having substantially the same diameter as the second small gear 22c. Further, the gear damper 32 is also a gear having substantially the same diameter as the rotating body side gear 16.

Further, the apparatus of this embodiment uses a spur gear having the gear specifications shown in FIG. When the drive system including the drive motor 10, the transmission gear train 12, and the rotating body 14 is referred to as a main vibration system, the gear inertial body 30 and the gear damper 32 serve as a sub-vibration system, and the natural vibration of the sub-vibration system is generated. Number f
Is represented by the following formula. f = 1 / 2π√ (K / J) (1) In the formula (1), K is the gear inertial body 30 and the gear damper 3.
2 is a composite value of gear rigidity, and J is a moment of inertia of the gear inertial body 30.

Here, in this embodiment, the natural frequency f of the sub-vibration system is meshed with the transmission gear train 12 of the main vibration system, which is one of the vibration components generated in the drive system (main vibration system). The gear inertial body 30 and the gear damper 3 are matched so as to match the frequency.
The K and J are set by appropriately selecting the size and material of No. 2. That is, as shown in FIG. 13, in the case where the peak of the speed fluctuation occurs near the meshing frequency 215 Hz of the first gear train 20 and the second gear train 22,
K and J are set so that the natural frequency f of the sub vibration system is around 215 Hz.

FIG. 3 shows the state of speed fluctuation of the apparatus of this embodiment.
Since the natural frequency f of the sub-vibration system acts as the vibration absorption frequency and the transfer gain near 215 Hz decreases, resonance can be avoided and the 215 Hz component of speed fluctuation can be suppressed. Therefore, in the present embodiment, the sub-vibration system including the gear inertial body 30 and the gear damper 32 functions as a dynamic damper, so that the speed fluctuation of the rotating body 14 can be reduced.

The gear inertial body 30 and the gear damper 32 as the dynamic dampers of this embodiment are arranged on the existing shafts (the fixed shaft 22a of the second gear train 22 and the rotary shaft 26 of the rotary body 14). Since it is not necessary to dispose a new shaft or the like inside the device, the assembly cost can be reduced. In the dynamic damper of the present embodiment, the number of teeth of the gear inertial body 30 is set to be smaller than the number of teeth of the gear damper 32 (see FIG. 2), and the gear inertial body 30 is accelerated and rotated with respect to the gear damper 32. Further, since the gear inertial body 30 is rotated via the gear damper 32, the combined value K of the gear rigidity is reduced, so that the same dynamic damper effect as that of other devices can be obtained. A small capacity (volume, weight) of the gear inertial body 30 is sufficient.

That is, as shown in FIG. 4, the specific dimensions and shapes of the gear inertial body 30 and the gear damper 32 of this embodiment are shown in Japanese Unexamined Patent Publication No. 2001-188438, which is a conventional dynamic damper (ring-shaped inertial member). Compared with the size and shape of the member in which the elastic body 7 is arranged on the inner peripheral side of the body 6, in the present embodiment, the length (axial dimension) is slightly increased (about 4 mm), but the volume and weight are both conventional. It decreases more. Therefore, since the dynamic damper has a reduced volume and weight, a wide mounting space for mounting the dynamic damper is not required, and the size and weight can be reduced.

When the rotation driving device of this embodiment is mounted on an image forming apparatus such as an electrophotographic laser printer, a copying machine or a facsimile, a highly reliable apparatus can be provided. Next, FIG. 5 shows a rotation drive device according to a second embodiment of the present invention. As a vibration component generated in the drive system (main vibration system), as shown in FIG. 13, there is an engagement frequency of 55 Hz between the second gear train 22 and the rotor-side gear 16. This meshing frequency is the second pinion 2
2c and the gear 16 on the rotor side, and the gear inertia body 30.
And the gear damper 32 meshes.

In the present embodiment, in addition to the rotary drive device of the first embodiment, the teeth of the gear damper 32 forming the dynamic damper are displaced from the teeth of the rotor side gear 16 by a half pitch in the circumferential direction. It is fixed to the rotary shaft 26 so as to be in the open position. As in the above configuration, the teeth of the gear damper 32 are circumferentially displaced by a half pitch with respect to the teeth of the gear 16 on the rotor side, so that as shown in FIG. A frequency component that reduces the meshing frequency 55 Hz with the gear 16 is generated to cancel the speed fluctuation, and the peak of the speed fluctuation can be suppressed. Therefore, in this embodiment, the speed fluctuation of the rotating body 14 can be further reduced.

Next, FIG. 7 shows a rotation drive device according to a third embodiment of the present invention. This embodiment is the second
Instead of the gear damper 32 of the rotary drive device of the embodiment, a gear damper 36 including an annular elastic body 34 is used. The gear damper 36 is integrated with an inner diameter ring 38 fixed to the outer circumference of the rotary shaft 26 via the annular elastic body 34 and has an outer diameter ring 4 having teeth formed on the outer circumference.
It is composed of 0 and.

The dynamic damper comprising the gear inertial body 30 and the gear damper 36 of the present embodiment uses the gear damper 36 in which the elastic body 34 is integrated, so that the viscosity is increased and the damping effect is enhanced, and the drive system ( The vibration component generated in the main vibration system) can be further reduced. That is, as is clear from the result of FIG.
Hz and 275 Hz peaks are lowered, and speed fluctuations can be further suppressed. Further, the gear damper 3 of the present embodiment
The specific dimensions and shape of No. 6 are shown in FIG.
-188438 conventional dynamic damper and Fig. 1
Compared with the dynamic damper of the first embodiment shown in, the rigidity of the present embodiment is further reduced by using the elastic body 34. Therefore, the dynamic damper is further reduced in volume and weight, and is small and lightweight. Can be achieved.

Next, FIG. 9 shows a rotation drive device of a fourth embodiment according to the present invention. This embodiment is the second
Another method of reducing the meshing frequency between the gear train 22 and the rotor-side gear 16 is to make the rotor-side gear 16 and the gear damper 32 forming the dynamic damper have the same number of teeth and different modules. The gear 16 on the rotor side is set to a larger gear than the gear damper 32.
As in the above configuration, the rotating body side gear 16 and the gear damper 3
2 has the same number of teeth and different modules to make the rotating body side gear 16 a larger gear compared to the gear damper 32, so that the mesh frequency of the second gear train 22 and the rotating body side gear 16 is 55 Hz. A frequency component for reducing the speed fluctuation is generated to cancel the speed fluctuation, and the peak of the speed fluctuation can be suppressed. Therefore, in this embodiment also, the rotating body 14
It is possible to reduce the speed fluctuation.

Next, FIG. 10 shows an outline of a rotary drive device of a fifth embodiment according to the present invention. In the present embodiment, an inertial body (hereinafter referred to as a pulley inertial body) 50 formed of a pulley is attached to the fixed shaft 22a forming the second gear train 22.
Is rotatably arranged, and a damper rotating body (hereinafter referred to as a pulley damper) 52 formed of a pulley is coaxially fixed to the rotating shaft 26 of the rotating body 14, and the rotation is transmitted between the pulley inertial body 50 and the pulley damper 52. A belt 54 is stretched around.

The pulley inertial body 50 is a member having substantially the same diameter as the second small gear 22c. The pulley damper 52 is a member having a larger diameter than the pulley inertial body 50. The sub-vibration system according to the present embodiment has the pulley inertial body 5
0, the pulley damper 52, and the rotation transmission belt 54. The natural frequency f of this sub-vibration system is also expressed by the following equation. f = 1 / 2π√ (K / J) (1) In the equation (1), K is the rigidity of the rotation transmission belt 54, and J is
Is the moment of inertia of the pulley inertial body 50.

In the present embodiment, the natural frequency f of the sub-vibration system is set to one of the vibration components generated in the drive system (main vibration system), for example, the meshing of the first gear train 20 and the second gear train 22. Frequency, the meshing frequency between the second gear train 22 and the rotor-side gear 16, the rotation frequency of the drive motor 10, the first gear train 20.
The K and J are set by appropriately selecting the size and material of the pulley inertial body 50 and the pulley damper 52 so as to match the rotation frequency of the above.

Therefore, in the present embodiment, the sub-vibration system including the pulley inertial body 50 and the pulley damper 52 functions as a dynamic damper, so that the speed fluctuation of the rotating body 14 can be reduced. In addition, the pulley inertial body 50 and the pulley damper 52 as the dynamic dampers of the present embodiment include the existing shafts (the fixed shaft 22a of the second gear train 22,
Since it is arranged on the rotation shaft 26) of the rotating body 14 and a new shaft or the like does not have to be arranged inside the device, the assembling cost can be reduced.

Further, in the dynamic damper of this embodiment, the pulley damper 52 is a member having a larger diameter than the pulley inertial body 50, and the pulley inertial body 50 to which the rotational force is transmitted from the pulley damper 52 via the belt 54 is accelerated. Since the combined value K of the dynamic damper rigidity further decreases due to the rotation, the pulley inertial body 50 having a small capacity (volume, weight) can be used even when the same dynamic damper effect as in other devices is obtained. I'm done. Therefore, since the dynamic damper has a reduced volume and weight, a wide mounting space for mounting the dynamic damper is not required, and the size and weight can be reduced.

When the rotation driving device of this embodiment is also mounted on an image forming apparatus such as an electrophotographic laser printer, a copying machine, or a facsimile, a highly reliable device can be provided. Further, FIG. 11 shows a sixth embodiment according to the present invention. In this embodiment, a pulley damper 58 having an annular elastic body 56 is used instead of the pulley damper 52 of the rotary drive device of the fifth embodiment. The pulley damper 58 is integrated with an inner diameter ring 60 fixed to the outer periphery of the rotary shaft 26 via the annular elastic body 56, and an outer peripheral surface is formed with a pulley surface with which the belt 54 is engaged. And a radial ring 62.

The dynamic damper of this embodiment uses the pulley damper 58 in which the elastic body 56 is integrated, so that the viscosity is increased and the damping effect is enhanced, so that the drive system (main vibration system).
It is possible to further reduce the vibration component generated in. Further, in this embodiment, since the rigidity is further reduced by using the elastic body 56, the dynamic damper has a further reduced volume and weight, and the size and weight can be reduced.

In the above-described first embodiment, the natural frequency of the sub-vibration system (the vibration absorption frequency of the dynamic damper) f
Is made to match the meshing frequency of the transmission gear train 12 of the main vibration system, which is one of the vibration components generated in the drive system (main vibration system), but the gist of the present invention is not limited to this. Instead, the meshing frequency between the second gear train 22 and the rotor-side gear 16, the rotation frequency of the drive motor 10, the first gear train 20.
Alternatively, even if the rotation frequency of the second gear train 22 and the excitation switching frequency of the drive motor 10 are matched, the same similar effect can be obtained.

Further, in the first and fifth embodiments, more detailed description will be given of matching with the excitation switching frequency of the drive motor 10. When a stepping motor is used as the drive motor 10, the drive motor 10 rotates at a constant angle. Vibration occurs due to the stepping of the motor. The frequency of this vibration corresponds to the rotation speed of the stepping motor fs
(Rps) When the number of steps per rotation is sm, it is determined by (fs × sm). Therefore, the vibration absorption frequency f of the dynamic damper of the first and fifth embodiments is
By setting the frequency to be a frequency generated by the rotation of the stepping motor, this vibration component can be reduced.

When the drive motor 10 has a k-pole and n-phase configuration, it may have a vibration component when switching the respective excitations. Such a vibration component may affect the speed fluctuation of the rotating body 14. The excitation switching frequency of the phase generated here is determined by (k × n). Therefore, by setting the vibration absorption frequency f of the dynamic damper of the first and fifth embodiments to the excitation switching frequency of the phase of the drive motor 10, this vibration component can be reduced.

[0037]

As described above, according to the invention described in claim 1, the inertia body is rotatably arranged on the predetermined fixed shaft constituting the transmission gear train, and the damper rotating body is provided on the drive shaft. By fixing the drive shaft coaxially and transmitting the rotation of the drive shaft to the inertial body through the damper rotating body to form a dynamic damper, it is possible to reduce the specific frequency by the dynamic damper.

According to a second aspect of the present invention, the vibration absorption frequency of the dynamic damper is set to the meshing frequency of the transmission gear train, the rotation frequency of the drive motor, the rotation frequency of the rotary gear train, and the drive motor. Since the excitation switching frequency is matched with any one of the switching frequencies, it is possible to reliably reduce the speed fluctuation of the rotating body caused by the vibration. Further, according to the inventions of claims 3 to 5, the effects of claims 1 and 2 can be obtained, and an inertia body and a damper rotating body having a simple structure are arranged on the existing fixed shaft and drive shaft. Since it is only necessary, it is possible to reduce the assembly cost.

According to the invention described in claim 6, the effects described in claims 1 to 5 can be obtained, and the rotation of the damper rotating body is accelerated to be transmitted to the inertial body, thereby reducing the volume. Since the inertial body of weight can be used, the dynamic damper can be made smaller and lighter. Further, according to the invention of claim 7, the effects of claims 1 to 6 can be obtained, and the inner diameter portion of the damper rotating body is fixed to the drive shaft via the annular elastic body. The viscosity is increased, the damping effect is enhanced, and the speed fluctuation of the rotating body can be reduced. Further, since the elastic body is used, the damper rotating body is reduced in volume and weight, so that it is possible to further reduce the size and weight of the dynamic damper.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a rotary drive device of a first embodiment according to the present invention.

FIG. 2 is a table showing specifications of each gear that constitutes the first embodiment.

FIG. 3 shows the frequency 21 of the vibration components generated in the drive system.
6 is a graph showing that the velocity component near 5 Hz is suppressed.

FIG. 4 is a table showing the shapes of the respective constituent members of the conventional device and the embodiment according to the present invention.

FIG. 5 is a diagram showing a main part of a rotation drive device according to a second embodiment of the present invention.

FIG. 6 shows a frequency 55 among the vibration components generated in the drive system.
It is a graph which shows the state where the frequency fluctuation which reduces the vicinity of Hz is generated, and the speed fluctuation is offset.

FIG. 7 is a diagram showing a main part of a rotation drive device according to a third embodiment of the present invention.

FIG. 8 shows the frequency 17 among the vibration components generated in the drive system.
It is a graph which shows the state where the frequency fluctuation which reduces the 0Hz and 275Hz vicinity generate | occur | produces, and speed fluctuation is suppressed.

FIG. 9 is a diagram showing a main part of a rotation drive device according to a fourth embodiment of the present invention.

FIG. 10 is a schematic view showing a rotation drive device of a fifth embodiment according to the invention.

FIG. 11 is a diagram showing a main part of a rotation drive device according to a sixth embodiment of the present invention.

FIG. 12 is a diagram showing a conventional rotary drive device.

FIG. 13 is a graph showing vibration components generated in a drive system of a conventional rotary drive device.

FIG. 14 is a perspective view showing a conventional rotary drive device including a dynamic damper.

FIG. 15 is a perspective view showing a conventional rotary drive device including a dynamic damper at a position different from that of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Drive motor 12 Transmission gear train 14 Rotating body 16 Rotating body side gear 18 Motor gear 20a Fixed shaft 20b First large gear 20c First small gear 20 First gear train 22a Fixed shaft (Inertia is rotatably fixed 22b Second large gear 22c Second small gear 22 Second gear train 26 Rotation shaft (driving shaft) 30 Gear inertia body (inertia) 32 Gear damper (damper rotor) 34 Elastic body 36 Gear damper (damper rotor) ) 50 pulley inertial body (inertial body) 52 pulley damper (damper rotating body) 54 rotation transmission belt 56 elastic body 58 pulley damper (damper rotating body)

Claims (7)

[Claims] 1. A rotary drive device comprising: a rotating body; a drive shaft fixed to the rotating body; and a drive motor drivingly connected to the drive shaft via a transmission gear train. An inertial body is rotatably arranged on a predetermined fixed shaft that is configured, and a damper rotating body having a diameter equal to or smaller than the outer diameter of the rotating body is coaxially fixed to the drive shaft, and the rotation of the drive shaft is the A rotary drive device configured as a dynamic damper by transmitting to the inertial body through a damper rotating body. 2. The vibration absorption frequency of the dynamic damper is selected from one of a meshing frequency of the transmission gear train, a rotation frequency of the drive motor, a rotation frequency of the transmission gear train, and an excitation switching frequency of the drive motor. The rotation drive device according to claim 1, wherein the rotation drive device is matched with the frequency. 3. The inertial body is a gear inertial body having teeth on its outer circumference, and the damper rotating body is a gear damper meshing with the gearing inertial body having teeth on its outer circumference. The rotary drive device according to claim 1. 4. The teeth of the transmission gear fixed to the drive shaft of the transmission gear train and the teeth of the gear damper are shifted by a half pitch in the circumferential direction so that the meshing frequency of the transmission gear train can be made uniform. 4. The rotary drive device according to claim 3, wherein frequency components whose phases are shifted by a half cycle are generated. 5. The inertial body is a pulley inertial body having a belt engaging surface on its outer circumference, and the damper rotating body is a pulley damper having a belt engaging surface on its outer circumference, and the pulley inertial body and the pulley damper are connected to each other. The rotation drive device according to claim 1 or 2, wherein a rotation transmission belt is stretched between them. 6. The rotary drive device according to claim 1, wherein the rotation of the damper rotating body is accelerated and transmitted to the inertial body. 7. The rotary drive device according to claim 1, wherein an inner diameter portion of the damper rotating body is fixed to the drive shaft via an annular elastic body.