JPH09250606A - Gear transmission device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the deviation of displacement when the body to be driven is rotated in a gear transmission device transmitting the rotation from the gear of the driving side to the gear of the driven side through the two gears provided on the same shaft. SOLUTION: There are provided a first gear 1 connected with a drive source side, a second gear 2 connected with a body to be driven side, a third gear 3 engaged with the first gear 1, and a fourth gear 4 attached to the same shaft as one of the third gear 3 and engaged with the second gear 2 as a gear transmission device, and the number of teeth of one of the third gear 3 and the fourth gear 4 is made to be odd times the number of teeth of the other. Then, the timing when the fluctuation of rotation speed of gears caused by the engagement of the first gear and the third gear becomes a maximum is made to be substantially agreed with the timing when the fluctuation of rotation speed of gears resulting from the engagement of the second gear and the fourth gear becomes a maximum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear transmission device suitable for rotating a driven body which is required to suppress displacement deviation during rotation, such as an image carrier of an image forming apparatus or a sheet conveying apparatus. . The present invention also relates to an image forming apparatus which is provided with such a gear transmission device and drives an image carrier and a sheet conveying device.

[0002]

For example, in an image forming apparatus, an image bearing member such as a photosensitive drum or a photosensitive belt, or a drum-shaped or belt-shaped sheet conveying device is installed from a predetermined position on the sheet. Since it is necessary to avoid image shift as much as possible, extremely high precision rotation performance is required. Further, in a multicolor image forming apparatus developed in recent years, color unevenness and color misregistration occur unless each color is formed at an accurate position on a sheet, and particularly high rotation accuracy is required.

However, the conventional gear transmission for driving the image carrier and the sheet conveying device has the following problems due to the meshing ratio of the gears. This will be described with reference to FIGS. 1 to 3. FIG. 1 shows a gear transmission, in which (A) is a perspective view and (B) is a plan view. In the figure, reference symbol M indicates a motor as a drive source. The first gear 1 is fixed to the first rotating shaft A1 that is the rotating shaft of the motor M. Reference numeral 2 indicates a second gear, and a second rotation axis A2 to which the second gear 2 is fixed.
A driven body, for example, a photosensitive drum is fixed to.

The first gear 1 is in mesh with the third gear 3 and the second gear 2 is in mesh with the fourth gear 4. Both the third gear 3 and the fourth gear 4 are
It is fixed to the third rotation axis A3. Accordingly, the rotation of the motor M is decelerated and transmitted to the second rotation shaft A2 via the gears of the first gear 1, the second gear 2, the third gear 3, and the fourth gear 4. It

Here, it is assumed that the meshing ratio of the first gear 1 and the third gear 3 and the meshing ratio of the second gear 2 and the fourth gear 4 are both meshing ratio ε = 1.5. To do. FIG. 2 shows a change in the rotational speed caused by the meshing between the first gear 1 and the third gear 3 in this case. In FIG. 2, the total of the sections a, b, and c that are connected by one straight line is 1
It is a period from the time when one tooth starts to contact the other gear to the time when the contact ends. In each period, the section a is a section in which one tooth starts to come into contact with the gear of the other party, and the section c is one.
This is a section in which one tooth is about to end contact with the other gear. The section b is an intermediate section. The time T required to rotate the gear by one pitch t is the total time of the section a and the section b for each tooth. As shown in the figure,
The section a for one tooth exactly coincides with the section c for the immediately preceding tooth. That is, sections a and c
Then, two teeth come into contact with the other gear, and in section b, 1
Only one tooth is in contact with the other gear.

Since the meshing ratio ε is 1.5, assuming that the time required to rotate the gear by one pitch t is T, the intervals a and b are equal, that is, It becomes 0.5T. ε = 1.5 = (0.5T × 2 + 0.5T × 1) ÷ T Note that the first term in the parentheses on the right side of the above equation is the time during which two gears at one pitch t come into contact with the other gear. (0.5
T) is multiplied by the number of contact teeth, and the second term is the time (0.5T) in which one gear contacts the other gear, multiplied by the number of contact teeth 1. Further, since the section a and the section c are also equal, the sections a, b, and c are all 0.5T.

As described above, in the rotation of the gear, the section a (section c) in which two teeth contact the mating gear and the section b in which one tooth contacts the mating gear are periodically repeated. As a result, speed fluctuations as shown in FIG. 2 occur. This is because, while the transmission torque is constant, in the section b where one tooth comes into contact, the load applied to one tooth becomes large and the bending of the tooth becomes large correspondingly, so This is because, in the section a (section c) in which the teeth come into contact with each other, the load applied to one tooth becomes small and the bending of the tooth becomes small.
Then, since it takes time to deform such a tooth, the rotation speed does not change rapidly but changes so as to draw a sine curve as shown in FIG. It should be noted that such a change in the rotational speed appears in the third gear 3 and the first gear 1 as well, but due to the engagement of the fourth gear 4 and the second gear 2, the change in the second gear is eventually caused. Is transmitted to the rotation axis A2 of the second rotation axis A2 and appears as a change in the rotation speed of the second rotation axis A2.

For the same reason as described above, the change in rotation speed is also caused by the meshing between the fourth gear 4 and the second gear 2 as shown in FIG. in this case,
The cycle of speed change becomes longer because the number of teeth of the fourth gear 4 is smaller than that of the third gear 3. This change in the rotation speed appears in the fourth gear 4 and the second gear 2 as well, and therefore appears as a change in the rotation speed of the second rotation axis A2. Therefore, finally, the change in the rotation speed generated on the second rotation axis A2 appears as the sum of the change shown in FIG. 2 and the change shown in FIG.

Such a change in rotational speed causes a displacement of the driven body during rotation. If the driven body is an image carrier such as a photoconductor drum or a photoconductor belt in an image forming apparatus, or a drum-shaped or belt-shaped sheet conveying device, an image may be displaced from a predetermined position. In particular, in a multicolor image forming apparatus, color unevenness or color misregistration occurs.

For such a problem, it is widely practiced to mount an inertial load (generally a flywheel) on the second rotary shaft A2 or another rotary shaft to suppress speed fluctuation. However, in this case, the manufacturing cost and weight increase associated with the installation of the inertial load, and the cost increase due to the necessity of adopting an expensive bearing are caused. Further, the space for providing the inertial load causes a restriction in downsizing the device or providing other components.

Further, JP-A-4-156473, JP-A-6-133122 and JP-A-6-2493.
As disclosed in Japanese Patent Laid-Open No. 21-21, there is proposed a technique of providing a vibration absorbing member between a rotary shaft and a driven body to damp speed fluctuations. However, in these techniques, the driven body is However, there is a concern that the position accuracy itself will be reduced, and eventually it will not be useful in preventing displacement deviation. Further, in order to provide a vibration absorbing member between the rotary shaft and the driven body and to improve the positional accuracy of the driven body, the dimensional error at the time of manufacturing must be made extremely small, which increases the manufacturing cost. It is thought that.

Further, as disclosed in Japanese Patent Application Laid-Open No. 6-318024, in a gear transmission device including a drive gear, one idle gear, and a driven gear, the drive gear and the idle gear are A technique has also been proposed in which the meshing position and the meshing position of the idle gear and the driven gear are shifted by about a half pitch. According to this, the fluctuation of the periodical displacement between the drive gear and the idle gear differs from the fluctuation of the displacement of the idler gear and the driven gear by a half pitch, which results in the periodical change between the drive gear and the idler gear. The maximum value of the fluctuation of the displacement and the minimum value of the fluctuation of the displacement of the idle gear and the driven gear are overlapped with each other, and consequently the fluctuation of the displacement of the driven gear is prevented. However, this technique is applicable only to a gear transmission device in which a driving gear and a driven gear are linked by a single idle gear, and two coaxial gears are provided in the middle as shown in FIG. It is not applicable to the reduction gear transmission or the speed increasing gear provided.

The present invention has been made in consideration of the above problems, and a gear on the drive side is provided through two gears provided coaxially without increasing the manufacturing cost and increasing the size of the device. In a gear transmission device that transmits rotation from a driven gear to a driven gear, it is an object of the present invention to suppress displacement deviation of a driven body during rotation. Another object of the present invention is to provide an image forming apparatus capable of reducing image shift.

[0014]

In order to solve the above problems, in the gear transmission according to the present invention, the first gear connected to the drive source side and the second gear connected to the driven body side.
Gear, a third gear meshed with the first gear, and a second gear mounted coaxially with the third gear.
And a fourth gear meshed with the gear of
And one of the fourth gears have a number of teeth that is an odd multiple of the other, and the maximum variation in the rotational speed of the gear due to the meshing of the first gear and the third gear is And the timing at which the change in the rotation speed of the gear due to the meshing of the second gear and the fourth gear reaches the maximum value substantially coincides with each other.

In this structure, the timing at which the fluctuation of the rotation speed of the gear due to the meshing of the first gear and the third gear reaches the maximum value and the meshing of the second gear and the fourth gear Focusing on the shift in the circumferential displacement corresponding to the integrated value of the fluctuations in the rotation speed by making the timing at which the fluctuations in the rotation speed of the gears reach the maximum value substantially coincide, the first gear and the third gear The timing at which the displacement deviation due to the meshing with and reaches the maximum value coincides with the timing at which the displacement deviation due to the meshing between the second gear and the fourth gear reaches the minimum value. Further, there are a timing at which the displacement deviation due to the meshing of the first gear and the third gear has a minimum value and a timing at which the displacement deviation due to the meshing of the second gear and the fourth gear has a maximum value. Match. Therefore, as a result, the displacement of the displacement of the driven body in the circumferential direction is suppressed. In addition,
Since one of the third gear and the fourth gear has the number of teeth that is an odd multiple of the other, the timings thereof do not gradually shift even if the gear continues to rotate. Under this configuration, it is not necessary to provide an accessory such as a vibration absorber or an inertial load for damping or suppressing the speed fluctuation in the gear transmission device, which causes an increase in manufacturing cost and an increase in size of the device. It is also prevented.

In order to achieve the synchronous relationship of the deviation of the rotational speed as described above, the meshing ratio of the first gear and the third gear and the mesh ratio of the second gear and the fourth gear. The meshing ratio is approximately 1.5, and one tooth of the first gear corresponds to one tooth of the third gear at a pitch point of meshing between the first gear and the third gear. When one of the teeth of the second gear and one of the teeth of the fourth gear are located on the pitch point of the meshing between the second gear and the fourth gear, It is advisable to contact with and press this.

Further, in the image forming apparatus according to the present invention, the above-mentioned gear transmission device and an image carrier which is connected to the second gear as the driven body and has a visible image formed on the surface thereof. It is characterized in that it is provided with a conveying means for conveying the sheet, and a transfer means for transferring the visible image on the image carrier to the sheet conveyed by the conveying means. As described above, by applying the present invention to the image forming apparatus, it is possible to reduce the disturbance of the image due to the displacement of the circumferential displacement of the image carrier. Particularly, in the case of the other-color image forming apparatus, it contributes to prevention of defects such as color unevenness and color shift.

Alternatively, the above-mentioned gear transmission device, a movable image carrier on the surface of which a visible image is formed, and a conveying means which is connected to the second gear as the driven body and conveys a sheet, A transfer unit that transfers the visible image on the image carrier to the sheet conveyed by the conveying unit may be provided. In this case, it is possible to reduce the image disturbance due to the displacement of the displacement of the conveying unit that conveys the sheet in the circumferential direction, and in the case of the other-color image forming apparatus, the uneven color is generated as described above. This will contribute to the prevention of defects such as color shift and color shift.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1. First Embodiment A. First Embodiment Basic Configuration of Embodiment The basic configuration of the embodiment of the present invention is the same as the configuration of FIG. 1 described above, but the number of teeth of the third gear 3 is set to an odd multiple of the number of teeth of the fourth gear 4. ing. And the first gear 1 and the third
The timing at which the variation of the rotation speed of the gear due to the meshing with the gear 3 of FIG. 3 becomes the maximum value and the timing at which the variation of the rotation speed of the gear due to the meshing of the second gear 2 and the fourth gear 4 reaches the maximum value Make sure they match. Specifically, how to match the extreme values of speed fluctuations will be described later.

B. Operation of the Embodiment Next, the operation when the extreme values of the speed fluctuations are made to coincide with each other will be described. B-1. Velocity Fluctuation and Displacement Fluctuation in the Embodiment FIG. 4 is a graph showing the results of measuring the temporal variation of the rotational speed of the second rotating shaft A2 that is the driven shaft, and FIG. 5 shows the rotation shown in FIG. It is a graph which shows the result of having measured the time variation of the ingredient which constitutes a gap of speed. In this measurement,
The meshing ratio between the first gear 3 and the third gear 3 is also the second gear 2
The meshing ratio of the fourth gear 4 and the fourth gear 4 was also set to about 1.5. Also,
The number of teeth of the third gear 3 is three times the number of teeth of the fourth gear 4.

In FIG. 5, reference numeral VA is the first gear 1
Component caused by meshing between the gear and the third gear 3, reference symbol V
B indicates a deviation component generated by the meshing between the second gear 4 and the fourth gear 4. Both the components VA and VB draw a sine curve as described above. The cycle of the component VA was about 44 msec, and the cycle of the component VB was about 132 msec. This is because the number of teeth of the third gear 3 is set to be three times the number of teeth of the fourth gear 4 so that the cycle of the component VB becomes three times the cycle of the component VA.

Here, as shown in FIG. 5, the components VA, V
The timing of the extreme value of B is matched. That is, the timing when the component VB takes the maximum value is always the component V
The component VB is matched with the timing when A takes the maximum value.
The timing of taking the minimum value is always matched with the timing of taking the minimum value of the component VA. As a result, FIG.
As shown in (2), on the second rotation axis A2, the deviation of the rotation speed is amplified in a predetermined cycle.

FIG. 6 is a graph showing the result of measuring the time variation of the displacement deviation in the rotation direction of the second rotation axis A2, and FIG. 7 is the time of the component forming the displacement deviation shown in FIG. It is a graph which shows the result of having measured the dynamic variation. In FIG. 7, reference numeral DA is a deviation component generated by the meshing of the first gear 1 and the third gear 3, and reference numeral DB is the second gear 2 and the fourth gear.
The shift component caused by the meshing with the gear 4 is shown.

As described above, the velocity deviation components VA, VB
As a result of matching the extreme values of, the component DA always takes the minimum value at the timing when the component DB has the maximum value.
Further, at the timing when the component DB has the minimum value, the component DA always has the maximum value. Therefore, in the resultant displacement shift shown in FIG. 6, the canceling action of the components DA and DB is caused in the vicinity of the extreme value of the waveform of the longer period due to the component DB.

The reason for this will be described. First, the displacement is differentiated with respect to time to obtain the velocity. Therefore, when the velocity shift is represented by a sine curve, the displacement shift is represented by a cosine curve (cos'θ = -sinθ). That is, the displacement shift occurs with a phase shift of one quarter cycle from the velocity shift. Here, as is clear from comparison between FIG. 7 and FIG. 5, the displacement component DA of the displacement is the component VA of the velocity.
Occurs a quarter cycle (about 11 msec) after the
B is generated with a delay of one quarter cycle (about 33 msec) from the component VB. As a result, the component DA has the minimum value at the timing when the displacement component DB of the displacement has the maximum value, and the component DA has the maximum value at the timing when the component DB has the minimum value.

B-1. Velocity Fluctuation and Displacement Fluctuation in Comparative Example 1 Next, the velocity fluctuation and displacement fluctuation of one comparative example (referred to as Comparative Example 1) were similarly measured. In Comparative Example 1, the meshing ratio between the first gear 1 and the third gear 3 and the meshing ratio between the second gear 2 and the fourth gear 4 were both set to about 1.5. Also, the third
The number of teeth of the gear 3 is 3 times the number of teeth of the fourth gear 4.
These points are the same as those in the above-described embodiment, but the above-described variation of the rotation speed is not synchronized.

FIG. 8 shows a second rotating shaft A2 which is a driven shaft.
9 is a graph showing the results of measuring the temporal fluctuations of the rotation speed, and FIG. 9 is a graph showing the results of measuring the temporal fluctuations of the components forming the deviation of the rotation speeds shown in FIG. In FIG. 9, similarly to the above, the cycle of the component VA of the rotational speed deviation is about 44 msec, and the cycle of the component VB is about 132 msec. Here, the component VA takes the minimum value at the timing when the component VB becomes the maximum value, and the component VB takes the maximum value at the timing when the component VB becomes the minimum value.

FIG. 10 is a graph showing the result of measuring the time variation of the displacement deviation in the rotational direction of the second rotation axis A2, and FIG. 11 is the time of the component forming the displacement deviation shown in FIG. It is a graph which shows the result of having measured the dynamic variation. In Comparative Example 1, the offset components of the displacement components DA and DB are canceled, but as described above, since the fluctuations in the rotation speed are not synchronized, as in the embodiment, the maximum value of the component DB is reduced. The component DA does not always have the minimum value at the timing, but the component DA does not always have the timing at the minimum value of the component DB.
Is not the maximum value. Rather, the component VA takes the minimum value at the timing when the velocity deviation component VB becomes the maximum value, and the component VB takes the maximum value at the timing when the component VB becomes the minimum value. The component DA takes the maximum value at the timing of the value, and the component DA takes the minimum value at the timing of the minimum value of the displacement component DB of the displacement. Therefore, in the resulting displacement of the displacement of the second rotation axis A2 in the rotation direction, the peaks in which the components DA and DB are amplified are generated as shown in FIG.

In FIG. 10, the resulting maximum displacement of the second rotation axis A2 in the rotational direction is about +16.
μm, and the minimum value is about −16 μm. On the other hand, in the above-described embodiment, as shown in FIG. 6, the maximum value of the resulting displacement deviation in the rotation direction of the second rotation axis A2 is approximately +11 μm, and the minimum value thereof is approximately −11 μm. . FIG. 12 is a graph showing the result of analyzing the ratio of displacement per unit time for each displacement deviation in the embodiment, and FIG. 13 is a similar graph in Comparative Example 1. According to the analysis result, in the embodiment, the maximum value of the displacement deviation is +
11 μm, the minimum value is −12 μm, the maximum value of displacement deviation is +16 μm, and the minimum value is −16 μm. In any case, it was confirmed that the displacement could be reduced in the embodiment.

B-2. Velocity Fluctuation and Displacement Fluctuation in Comparative Example 2 Next, the velocity fluctuation and displacement fluctuation of another comparative example (referred to as Comparative Example 2) were similarly measured. In Comparative Example 2, the meshing ratio between the first gear 1 and the third gear 3 and the meshing ratio between the second gear 2 and the fourth gear 4 were both set to about 1.5. However,
The number of teeth of the third gear 3 is four times the number of teeth of the fourth gear 4.

FIG. 14 shows a second rotating shaft A which is a driven shaft.
2 is a graph showing the result of measuring the temporal variation of the rotation speed of FIG. 2, and FIG. 15 is a graph showing the result of measuring the temporal variation of the components forming the deviation of the rotational speed shown in FIG.
In FIG. 15, the cycle of the component VA is about 33 msec, and the component V is
The period of B became about 132 msec. This is because the number of teeth of the third gear 3 is set to be four times the number of teeth of the fourth gear 4 so that the cycle of the component VB becomes four times the cycle of the component VA.

FIG. 16 is a graph showing the result of measuring the time variation of the displacement deviation in the rotation direction of the second rotation axis A2, and FIG. 17 is the time of the component forming the displacement deviation shown in FIG. It is a graph which shows the result of having measured the dynamic variation. In Comparative Example 2, the offset components of the displacement components DA and DB are partially caused, but as described above, the fluctuations in the rotation speed are not synchronized, and therefore, as in the above embodiment, The component DA does not necessarily have the minimum value at the timing of the maximum value of the component DB, and the component DA does not necessarily have the maximum value at the timing of the minimum value of the component DB. Therefore, in the resulting displacement of the displacement of the second rotation axis A2 in the rotation direction, peaks which are amplified by the components DA and DB are generated as shown in FIG.

In FIG. 16, the resulting maximum displacement of the second rotation axis A2 in the rotational direction is about +14.
μm, and the minimum value was about −14 μm. On the other hand, in the above-described embodiment, the maximum value of the resulting displacement deviation in the rotation direction of the second rotation axis A2 is +11 μm.
And the minimum value was −11 μm. Also in this case, it was confirmed that the displacement could be reduced in the embodiment.

In addition, in Comparative Example 2, as in the embodiment, the component VA always has the maximum value at the timing when the velocity deviation component VB has the maximum value, and the component VB always has the minimum value at the timing. It is impossible to make VA take the minimum value. The reason is that the number of teeth of the third gear 3 is four times the number of teeth of the fourth gear 4, so if the timing of the maximum value of the component VB matches the timing of the maximum value of the component VA, the component This is because the timing of the minimum value of VB also matches the timing of the maximum value of the component VA (see FIG. 15). If the timing of the speed deviation component is set in this way, the minimum value is amplified although the maximum value of the rotation speed deviation can be suppressed.

In addition to the above comparative example, if the third
If the number of teeth of the third gear 3 and the number of teeth of the fourth gear 4 are not in an integral multiple relationship, it is obvious that a large displacement shift will occur sometime while the motor M continues to rotate. Is.

As described above, according to this embodiment, the second
It is possible to reduce the deviation of the displacement of the rotation axis A2 in the rotation direction. This is nothing but reducing displacement deviation in the rotational direction of the driven body connected to the second rotation axis A2. If the driven body is, for example, an image carrier such as a photosensitive drum or a photosensitive belt in an image forming apparatus, or a drum-shaped or belt-shaped sheet conveying device,
The deviation of the image from the predetermined position on the sheet is reduced, which leads to suppression of color unevenness and color deviation especially in a multicolor image forming apparatus.

In the present embodiment, as shown in FIG. 12, the displacement deviation is close to the extreme value in a large time ratio, but in the technical field of image forming apparatus, for example, an image generated as a result of the displacement deviation is generated. The deviation of the displacement cannot be visually identified unless it becomes a certain fixed value. Therefore, the deviation itself of the displacement is a problem, and as long as the deviation is within a predetermined range, the difference of FIG. It is almost unlikely that the time rate at which the displacement shift is near the extreme value becomes a problem.

D. Specific configurations of the embodiments Next, how to bring the advantages as described above, the timing at which the fluctuation of the rotational speed of the gear by engagement of the first gear 1 and the third gear 3 is the maximum value, A description will be given of whether or not the timing at which the fluctuation of the rotation speed of the gear due to the meshing of the second gear 2 and the fourth gear 4 becomes the maximum value is substantially matched.

What is desirable as this means is to actually rotate each gear and adjust the relative positional relationship of each gear while measuring the speed fluctuation. That is, if the positional relationship between the rotation shafts A1, A2, and A3 is predetermined, the relative teeth of the third gear 3 and the teeth of the fourth gear 4 in the circumferential direction of the second rotation shaft A2. Adjust the positional relationship. In this case, based on the relative positional relationship between the teeth of the third gear 3 and the teeth of the fourth gear 4 found as a result of such trial and error, the third gear 4 and the fourth gear 4 are made of resin or It is also possible to manufacture integrally with metal or the like. Alternatively, if the third gear 4 and the fourth gear 4 are attached to the third rotation axis A3 in a non-adjustable manner in the circumferential direction, the third rotation axis A3 may be used as the center of rotation. 1 gear 1 and 2
It is also possible to adjust the relative positional relationship with the gear 2.

However, in practice, it may be difficult to make such adjustment from the viewpoint of time and cost. Therefore, it is possible to synchronize the timing by the following means based on the design value of each gear and the relative positional relationship of each shaft. Note that, as shown in FIG. 5, the timing at which the fluctuation component VB of the rotational speed of the gear due to the meshing between the second gear 2 and the fourth gear 4 reaches the maximum value is always the first gear 1 and the third gear 4. The fact that the fluctuation component VA of the gear rotation speed due to the meshing with the gear 3 coincides with the timing at which it has the maximum value means that the fluctuation component of the rotation speed of the gear due to the meshing between the second gear 2 and the fourth gear 4. The timing when VB takes the minimum value is equivalent to the timing when the fluctuation component VA of the rotational speed of the gear due to the meshing between the first gear 1 and the third gear 3 always coincides with the minimum timing. Therefore, in the following, the timing at which the fluctuation of the rotational speed of the gear due to the meshing of the first gear 1 and the third gear 3 becomes the minimum value, and the gear due to the meshing of the second gear 2 and the fourth gear 4 Matching the timing at which the fluctuation of the rotation speed becomes the minimum value will be described.

FIG. 18 is a front view showing the gear transmission of the embodiment. Here, the first rotary shaft A1 to which the first gear 1 is mounted, the second rotary shaft A2 to which the second gear 2 is mounted, the third gear 3 and the fourth gear 4 are mounted. The position of the third rotation axis A3 is predetermined. As a specific example, the first rotation axis A1 and the second rotation axis A2 are 90 degrees about the third rotation axis A3.
Consider the case where they are arranged at an angular interval of °. The number of teeth of the third gear 3 is 30, and the number of teeth of the fourth gear 4 is 10. In this case, the angular interval of the pitch of the third gear 3 is 360 ° / 30 = 12 °, and the fourth gear 4
The angular interval of the pitch is 360 ° / 10 = 36 °.

The meshing ratio ε is 1.5 both between the first gear 1 and the third gear 3 and between the second gear 2 and the fourth gear 4. For convenience of explanation, the first gear 1
Rotates clockwise in the figure, and accordingly, the third gear 3 and the fourth gear 4 rotate counterclockwise, and the second gear 2 rotates clockwise.

FIG. 19A shows the speed fluctuation due to the meshing of the first gear 1 and the third gear 3, and FIG. 19B shows the speed fluctuation due to the meshing of the second gear 2 and the fourth gear 4. Shows variability. As described above, the section a is a section in which one tooth starts to come into contact with the mating gear, and also a tooth immediately before the tooth is about to end contact with the mating gear. That is, in the section a, two teeth are in contact with the counterpart gear, and in the section b, only one tooth is in contact with the counterpart gear. The total of the sections a and b forms one pitch t.

20 and 21 show an actual meshing state between the first gear 1 and the third gear 3. In FIG. 20, the tooth T ₁₁ of the first gear 1 comes into contact with the tooth T ₃₁ of the third gear 3 and starts to press it. Both gears 1, 3 at this time
The contact point of is Q _A1 . Thus, the point in time when one tooth of the first gear 1 contacts one tooth of the third gear 3 at the point Q _A1 corresponds to the start of the section a in FIG. 19 (A).

Next, in FIG. 21, the tooth T ₁₁ of the first gear 1 has finished contacting with the tooth T ₃₁ of the third gear 3. The contact point of both gears at the end of this contact is Q _A2 . In this way, the point at which one tooth of the first gear 1 contacts one tooth of the third gear 3 at the point Q _A2 is the section c in FIG. 19 (A).
Corresponds to the end of.

Due to the nature of the gear, the angle α formed by the contact start point Q _{A 1} and the pitch point P _A about the center O ₃ of the third gear 3 is the center point of the third gear 3. It is equal to the angle β formed by the contact end point Q _A2 and the pitch point P _A about O ₃ . Therefore, when the teeth T ₁₁ is just an intermediate to the end it starts to contact the teeth T _31, as shown in FIG. 18, the teeth T ₁₁ to be in contact with the tooth T ₃₁ at the pitch point P _A Become.

Referring now to FIG. 19, the contact start point Q
_The minimum speed is reached when the gears 1 and 3 are in contact with each other at _A1 and when the gears 1 and 3 are in contact with each other at the contact end point Q _A2 . Therefore, as shown in FIG. 18, the tooth T ₁₁ of the first gear 1 is the tooth T ₃₁ of the third gear 3 at the pitch point P _A.
It can be seen that the rotation speed of the third gear 3 is minimized when it comes into contact with and presses it.

The angular interval of the pitch of the third gear 3 is 1
2 °, and the total of the sections a and b forms one pitch t, and from the start of the section a to the end of the section c (in the angular interval between the contact start point Q _A1 and the contact end point Q _A2 Is equivalent to 1.5 t, the angular interval between the contact start point Q _A1 and the contact end point Q _{A2 of} the third gear 3 is 1
It is considered to be 8 °. Therefore, specifically, the above-mentioned angle α (= angle β) is about 9 °.

As described above, in the meshing relationship between the first gear 1 and the third gear 3, one tooth T ₁₁ of the first gear 1 which is the drive gear is the third at the pitch point P _A. When the tooth T ₃₁ of one of the gears 3 of the
The rotation speed of the gear 3 is minimized. This is considered to be similarly established in the meshing relationship between the fourth gear 4 and the second gear 2. That is, in this case, in FIG.
As shown in, at the pitch point P _B of both gears, one tooth T ₄₁ of the fourth gear 4 on the drive side comes into contact with one tooth T ₂₁ of the second gear 2 and presses it. While rotating, the rotation speed of the fourth gear 4 is minimized (see FIG. 19B).

Therefore, the first gear 1 and the third gear 3
In order to match the timing when the change in the rotation speed of the gear due to the engagement with the minimum value with the timing when the change in the rotation speed of the gear due to the engagement between the second gear 2 and the fourth gear 4 becomes the minimum value. 18, one tooth T ₁₁ of the first gear 1 and one tooth T ₃₁ of the third gear 3 are brought into contact with each other at a pitch point P _A , and further, the fourth gear 4 is rotated. One tooth T ₄₁ of the second gear 2 and one tooth T ₂₁ of the second gear 2 are arranged at the pitch point P _B.
Contact them with. In this case, the teeth T ₃₁ and T ₂₁ that receive the power transmission are the driving-side teeth T ₁₁ and T ₂₁ , respectively.
_It must also be located downstream of _{41 in the} direction of rotation.

In this way, the rotation axes A1, A2, A
If the positional relationship of No. 3 is predetermined, the relative positional relationship between the teeth of the third gear 3 and the teeth of the fourth gear 4 is adjusted in the circumferential direction of the second rotation axis A2. Alternatively, it is also possible to integrally form the third gear 3 and the fourth gear 4 based on the relative positional relationship of the teeth of each gear thus obtained. In this case, a metal may be used as a material for die casting, or a resin may be used as a material for molding.

As described above, the timings at which the fluctuations in the rotation speed are minimized can be matched. Strictly speaking, however, it is difficult to accurately match the timings at which the fluctuations in the rotation speed are minimized, because the material of the gear, the design value, and the like affect the tooth deformation. However, according to this, there is an advantage that timing can be easily and quickly synchronized.

E. Modification Example In the present embodiment, the first rotation axis A1 and the second rotation axis A2 are arranged at an angular interval of 90 ° about the third rotation axis A3. However, at what angular intervals are the first rotation axis A1 and the second rotation axis A2
Even if the gears are arranged, it is clear that if the gear teeth are brought into contact with each other at the pitch point in consideration of the rotation direction and the rotation direction is taken into consideration, the above-described speed variation timings can be synchronized. . FIG. 22 shows the first rotation axis A1.
Also, an example in which the second rotation axis A2 is arranged at an angular interval other than 90 ° about the third rotation axis A3 will be described. Also in this case, one tooth T ₁₁ of the first gear 1 and one tooth T ₃₁ of the third gear 3 are brought into contact with each other at the pitch point P _A , and the fourth gear 4 is rotated in the rotation direction. One tooth T
_{4 1,} the second one tooth T ₂₁ of the gear 2 so power transmission is made, it is sufficient to contact the teeth T ₄₁ and tooth T ₂₁ at the pitch point P _B.

Further, in the above embodiment, each rotation axis A
The positions of 1, A2 and A3 are determined in advance, and the relative positional relationship between the teeth of the third gear 3 and the fourth gear 4 is adjusted. However, conversely, the third gear 3 and the fourth gear 4
However, when it is attached to the third rotation axis A3 so that it cannot be adjusted in the circumferential direction, the relative position between the first gear 1 and the second gear 2 about the third rotation axis A3. You can also adjust the relationship. Referring to FIG. 22, first, with one tooth T ₃₁ of the third gear 3 in contact with one tooth T ₁₁ of the first gear 1, while shifting the position of the second rotation axis A2, From one tooth T ₄₁ of the fourth gear 4 to the second gear 2
It is sufficient to bring the tooth T ₄₁ and the tooth T ₂₁ into contact with each other at the pitch point P _B so that power is transmitted to one tooth T _{21 of the} above. It is also conceivable to shift the position of the first gear 1. In reality, in many cases, the positions of the rotary shafts A1, A2, A3 are previously determined at the design stage, and therefore, the teeth of the third gear 3 and the fourth gear 4 are set to be larger than in this example. It is considered that the relative positional relationship with the tooth is often determined later.

Further, in the above embodiment, the third gear 3
Although the number of teeth of the fourth gear 4 is an odd multiple of the number of teeth of the fourth gear 4, the number of teeth of the fourth gear 4 may be an odd multiple of the number of teeth of the third gear 3. In particular, in the case of a speed increasing gear, this is effective. Further, the above-mentioned embodiment relates to a spur gear, but in the case of a bevel gear and a helical gear,
The invention is likewise applicable. The same applies to a rack and pinion mechanism in which the driven gear is a rack.

2. Second Embodiment Next, a second embodiment of the present invention will be described. FIG.
As shown in FIG. 2, in the second embodiment, the second gear 2
Further, a fifth gear 5 is attached to the second rotating shaft A2 that supports the. The fifth gear 5 is meshed with the sixth gear 6 attached to the fourth rotation shaft A4. The present invention can be applied to such a gear transmission.

That is, in the present embodiment, the third gear 3
The number of teeth is not only an odd multiple of the number of teeth of the fourth gear 4, but the number of teeth of the sixth gear 6 is an odd multiple of the number of teeth of the fifth gear 5. Then, similarly to the above, the timing at which the fluctuation of the rotation speed of the gear due to the meshing of the first gear 1 and the third gear 3 becomes the maximum value, the second gear 2 and the fourth gear 4
The timing at which the change in the rotation speed of the gear due to the meshing with the gear 4 reaches the maximum value is substantially the same. Further, in this embodiment, at this timing, the fifth gear 5
And the sixth gear 6 meshes with each other at the timing when the variation of the rotation speed of the gear reaches the maximum value.

Specifically, regarding how to match the extreme values of the speed fluctuations, as described above, as a result of trial and error by actually rotating the gears, as a result of the trial and error, the matching method and the meshing position of the gears are set. There is a method of matching the pitch point with. The measure to match the meshing position of the gear with the pitch point is to bring one tooth T ₁₁ of the first gear 1 and one tooth T ₃₁ of the third gear 3 into contact with each other at the pitch point P _A. One tooth T ₄₁ of the fourth gear 4 and one tooth T ₂₁ of the second gear 2 are brought into contact with each other at a pitch point P _B , and one tooth of the fifth gear 5 and the sixth gear It is to make one tooth of 6 contact at the pitch point of both gears. In this case, it is also necessary that the tooth that receives power transmission be located on the downstream side in the rotation direction with respect to the tooth on the drive side.

FIG. 24 is a graph showing the result of measuring the temporal change of the rotation speed of the fourth gear 4 which is the final driven shaft, and FIG. 25 shows the deviation of the rotation speed shown in FIG. It is a graph which shows the result of having measured the time variation of the eggplant component. In this measurement, the meshing ratio between the first gear 1 and the third gear 3, the meshing ratio between the second gear 2 and the fourth gear 4, and the meshing ratio between the fifth gear 5 and the sixth gear 6 were measured. It was set to about 1.5. Further, the number of teeth of the third gear 3 is set to be three times the number of teeth of the fourth gear 4, and the number of teeth of the second gear 2 is set to be three times the number of teeth of the fifth gear 5.

In FIG. 5, reference numeral VA is the first gear 1
Component caused by meshing between the gear and the third gear 3, reference symbol V
B indicates a shift component generated by the meshing between the second gear 4 and the fourth gear 4, and reference symbol VC indicates a shift component generated by the meshing between the fifth gear 5 and the sixth gear 6. Components VA, VB, V
C also draws a sine curve. The cycle of the component VA is about 4
The period of 4 msec and the component VB was about 132 msec. This is because the number of teeth of the third gear 3 is three times the number of teeth of the fourth gear 4, so that the cycle of the component VB is three times the cycle of the component VA. The cycle of the component VC is about 3
It became 96 msec. This changes the number of teeth of the second gear 2 to the fifth
By setting the number of teeth of the gear 5 to 3 times, the period of the component VC becomes 3 times the period of the component VA.

Here, as shown in FIG. 5, the components VA and V
The timing of the extreme value of B is matched. That is, the timing when the component VC takes the maximum value is always the component V
The timing when B and VA take the maximum value is matched, and the timing when the component VC takes the minimum value must be the components VB and V.
It is matched with the timing when A takes the minimum value. As a result, as shown in FIG. 24, in the fourth rotation axis A4, the deviation of the rotation speed is amplified in a predetermined cycle.

FIG. 26 is a graph showing the result of measuring the time variation of the displacement deviation of the fourth gear 4 in the rotational direction, and FIG. 27 is the time component of the displacement deviation shown in FIG. It is a graph which shows the result of having measured fluctuation. In FIG. 27, reference numeral DA is a deviation component caused by the engagement of the first gear 1 and the third gear 3, reference numeral DB is a deviation component caused by the engagement of the second gear 2 and the fourth gear 4, and the reference numeral DC
Indicates a deviation component generated by the meshing of the fifth gear 6 and the sixth gear 6.

As described above, the velocity deviation components VA, V
As a result of matching the extreme values of B and VC, the component DB and DA always take the minimum value at the timing when the component DC has the maximum value. Further, at the timing when the component DC has the minimum value, the components DB and DA always have the maximum value. Therefore, in the resulting displacement shift shown in FIG. 26, the canceling action of the components DA, DB, and DC is caused near the extreme value of the waveform of the longer period due to the component DC.

As a result, the resulting displacement deviation of the fourth rotation axis A4 in the rotation direction is reduced to about ± 43 μm. On the other hand, if the speed fluctuations are not synchronized as described above, the displacement shift is ± 6.
It may be amplified to 0 μm or more. FIG. 28 is a graph showing the result of analyzing the ratio of displacement per unit time for each displacement deviation in the present embodiment. Also in this analysis result, the deviation of the displacement of the fourth rotation axis A4 in the rotation direction is about ± 43 μm. As described above, the present invention can be applied even when the number of gears is increased.

In the above embodiment, the number of teeth of the third gear 3 is an odd multiple of the number of teeth of the fourth gear 4,
Conversely, the number of teeth of the fourth gear 4 may be an odd multiple of the number of teeth of the third gear 3. In the above embodiment, the second gear 2
Although the number of teeth of the fifth gear 5 is an odd multiple of the number of teeth of the fifth gear 5, the number of teeth of the fifth gear 5 may be an odd multiple of the number of teeth of the second gear 2. In particular, in the case of a speed increasing gear, this is effective. Further, the above-mentioned embodiment relates to a spur gear, but in the case of a bevel gear and a helical gear,
The invention is likewise applicable. The same applies to the rack and pinion mechanism in which the final driven gear is a rack.

3. Application example 3-1. Application Example (1) FIG. 29 is a front view showing the overall configuration of an electrostatic color copying machine which is an image forming apparatus to which the present invention can be applied. This electrostatic color copying machine is provided with a platen glass 25, a sensor 26 for reading an image of a document, and a conveyor belt 23 for conveying the sensor 26 in an image reading section. Then, the sensor 26 reads the image on the lower surface of the document placed on the platen glass 25 while being transported by the transport belt 23.

Below the conveyor belt 23, a photosensitive drum (image bearing member) 9, a charging corotron 10 arranged around the photosensitive drum 9, an exposure device 7, a developing unit 11, a transfer drum (conveying means) 12, a transfer corotron. 15, cleaner 13
Etc. are provided. The photosensitive drum 9 is rotationally driven in the direction shown by the arrow in the figure. The charging corotron 10 uniformly charges the surface of the rotating photosensitive drum 9. The exposure device 7 irradiates a laser beam according to the image read by the sensor 26, the laser beam is reflected by the mirror 8 and is radiated on the surface of the charged photosensitive drum 9, thereby forming a latent image. To be done. The developing unit 11 includes four developing units 1.
It is a rotary drum including 1A, 11B, 11C and 11D. The developing devices 11A, 11B, 11C and 11D supply black, yellow, magenta and cyan toners to the photoconductor drum 9, respectively. Each time the photosensitive drum 9 rotates once, one of the developing devices 11A, 11B, 11C, and 11D supplies toner to the photosensitive drum 9, and toner is attached to the latent image one color at a time. Then, these toner images are sequentially laminated on the sheet attracted to the transfer drum 12, so that a color toner image is formed on the sheet.

The transfer drum 12 has a cylindrical film 12A supported between two disk-shaped supports, and is rotationally driven in the direction indicated by the arrow in the figure. A sheet is conveyed to the transfer drum 12 by the sheet feeding device 4 and the conveying device 20, and the sheet is attached to and supported by the transfer drum 12, and as the transfer drum 12 rotates, the photosensitive drum 9 and the transfer drum 12 are rotated. Is passed through the nip between. A transfer corotron (transfer means) 15 to which a bias voltage is applied is fixedly arranged inside the transfer drum 12. The transfer corotron 15 is opposed to the nip, and when the sheet is passed through the nip,
The toner image formed on the photosensitive drum 9 is attracted and transferred to the sheet by the electric field generated by the transfer corotron 15.

After the transfer of the toner image, the surface of the photosensitive drum 9 is cleaned by the cleaner 13 having a cleaning blade. A peeling corotron 16 is arranged near the transfer drum 12.
6 applies an electric field to the sheet onto which the toner image has been transferred in the direction of peeling from the transfer drum 12, thereby peeling the sheet from the transfer drum 12. A heat fixing device 21 is arranged on the left side of the transfer drum 12 in the figure. The sheet peeled by the peeling corotron 16 is conveyed to the heat fixing device 21, where the toner image on the sheet is fixed by being heated and pressed. After that, the sheet is discharged to the discharge tray 22. The sheets are transferred from the paper feed trays 17A, 17B, 17C or the manual feed tray 19 by the transfer device 20 to the transfer drum 12
It is supplied to.

The gear transmission according to the present invention can be applied not only for driving the above-mentioned photosensitive drum 9 which is an image carrier but also for driving the transfer drum 12 which is a sheet conveying means. Then, in any of these cases, as described above, it is possible to suppress the image shift and the color unevenness and color shift caused by the image shift.

3-2. Application Example (2) FIG. 30 is a front view showing the overall configuration of another image forming apparatus to which the present invention can be applied. In this example, a developing unit 11 and a charging roll 1 are provided around the photosensitive drum (image bearing member) 9.
0a and the cleaner 13 are arranged. Further, the image writing device 21 is arranged at a distance from the photosensitive drum 9. The image writing device 21 irradiates the surface of the photosensitive drum 9 uniformly charged by the charging roll 10 a with laser light, and writes an electrostatic latent image based on the image data read by the image reading device 26.

The developing unit 11 includes four developing units 11.
It is a rotary drum provided with A, 11B, 11C and 11D. The developing devices 11A, 11B, 11C and 11D supply black, yellow, magenta and cyan toners to the photoconductor drum 9, respectively. Specifically, with the first one rotation of the photosensitive drum 9, the electrostatic latent image of cyan is written to form a toner image of the same color, which is transferred onto the transfer belt (image carrier) 37 of the primary transfer device 30. To be done. In the next one rotation, a magenta electrostatic latent image is written to form a toner image of the same color, which is transferred onto the transfer belt 37 so as to be superposed on the cyan toner image. Then, while the photosensitive drum 9 rotates four times in this manner, the cyan to black toner images are sequentially superposed on the transfer belt 37, and a color toner image is formed on the transfer belt 37.

The primary transfer device 30 is arranged above the photosensitive drum 9. The primary transfer device 30 includes a drive roll 31,
A primary transfer roll 32, an idle roll 33, a backup roll 34, and an idle roll 35 are arranged clockwise in this order, and these drive roll 31 to idle roll 3 are arranged.
5, the transfer belt 37 is wound around the transfer belt 37 and is roughly configured. On the left side of the backup roll 34, contact with it,
A secondary transfer roll (transfer means) 40 that can be separated is arranged. The secondary transfer roll 40 is for transferring the color toner image laminated on the transfer belt 37 to the sheet S.

In the figure, reference numerals 60 and 61 denote paper feed trays,
Reference numerals 62 and 63 are feed rolls for feeding the sheets S contained in the paper feed trays 60 and 61 one by one. The feed rolls 62 and 63 supply the sheet S between the registration roll (conveying means) 64 and the pinch roll 65, and the registration roll 64 and the pinch roll 6
5 further supplies the supplied sheet S to the nip between the backup roll 34 and the secondary transfer roll 40. At that time, the sheet S is brought into close contact with the transfer belt 37, and the electric charge applied to the secondary transfer roll 40 causes the transfer belt 37 to move.
The color toner image held on is transferred to the sheet S.
The sheet S on which the transfer has been completed is conveyed to the heat fixing device 21, where it is heated and pressed to fix the toner image on the sheet S. After this, the sheet S is
It is discharged to the discharge tray 22.

The gear transmission according to the present invention is used not only for driving the photosensitive drum 9 which is the above-mentioned image carrier but also for driving the drive roll 31 for driving the transfer belt 37.
It is also applicable to drive the registration roll 64 that conveys the sheet. Further, the secondary transfer roll 4
0 is considered as a transporting means, and it is driven independently,
The gear transmission according to the invention can also be used for this drive.

3-3. Application Example (3) In the application example (2), the present invention is applied to an image forming apparatus having a primary transfer device 30.
It can also be applied to the image forming apparatus shown in FIG. In FIG. 31, the same components as those in FIG. 30 are designated by the same reference numerals.
Also in this case, the gear transmission according to the present invention can be used for driving the photoconductor drum 9 which is the above-mentioned image carrier or for driving the registration roll 64 which conveys the sheet. Further, the transfer roll 40 may be independently driven, and the gear transmission according to the present invention may be used for this drive.

3-4. Application Example (4) FIG. 32 is a front view showing still another image forming apparatus to which the present invention can be applied. This image forming apparatus is a so-called tandem type full-color image forming apparatus. In this figure, reference numeral 71 denotes a transfer belt (conveying means), and the transfer belt 71 is made of polyethylene tephretate (PET), polyvinylidene fluoride resin (PVDF), polyester, polycarbonate, polyether ether ketone, or the like. A belt made of a material having a high insulating property is formed into a belt shape, and both ends thereof are ultrasonically welded to form an endless belt. The transfer belt 71 is wound around a drive roll 72, a tension applying roll 73, and idler rolls 74 and 75, and is rotatable as shown by an arrow. The transfer belt 71 is
While being driven by the drive roll 72 and being given a tension to the tension applying roll 73, it travels around these rolls 72 to 75.

Above the transfer belt 71, rotatably arranged photosensitive drums (image bearing members) 9Y, 9M, 9C and 9K are arranged. Around these photosensitive drums 9Y, 9M, 9C, 9K, charging corotrons 10Y, 10M, 10C, 10K,
Not shown latent image writing device, developing device 76Y, 76M, 76C, 76K
Is arranged. Corotron for charging 10Y, 10M, 10C, 10K
Uniformly charges the surface of the photoconductor drums 9Y, 9M, 9C, 9K,
The latent image writing device irradiates the charged photosensitive drums 9Y, 9M, 9C, 9K with laser light based on the color separated writing command signal to form an electrostatic latent image. Developing device 76Y, 76M, 76C,
76K attaches toner to this electrostatic latent image to make it a visible image. The developing devices 76Y, 76M, 76C and 76K supply yellow, magenta, cyan and black toners to the photoconductor drums 9Y, 9M, 9C and 9K, respectively.

The transfer belt 71 is driven by a drive roll 72 to run while being in contact with the photosensitive drums 9Y, 9M, 9C, 9K, and the sheet S is on the surface of the transfer belt 71. The sheet S is adsorbed and comes into contact with the photosensitive drums 9Y, 9M, 9C and 9K as the transfer belt 71 travels. The sheet S is transported by the transport device 20 and supplied to the transfer belt 71. And
When the sheet S is released from the registration gate 77, the sheet S is pressed against the transfer belt 71 by the pressing roll 78 and is electrostatically adsorbed to the transfer belt 71 by the electric field of the adsorption corotron 79.

The photosensitive drum 9 as viewed from the transfer belt 71.
Transfer corotrons (transfer means) 80Y, 80M, 80C, and 80K are arranged on the opposite side of Y, 9M, 9C, and 9K. A positive voltage is applied to the transfer corotrons 80Y, 80M, 80C, 80K, and the negatively charged toner on the photoconductor drums 9Y, 9M, 9C, 9K by the electric field action caused by the corona discharge generated here. Are transferred to the sheet S on the transfer belt 71. In this way, the sheet S becomes the photosensitive drums 9Y, 9M, 9
Yellow, magenta, cyan, and black toners are transferred onto the sheet S each time the sheet passes through C and 9K.

The sheet S on which the multicolor toners have been transferred in this way reaches the sheet discharging corotron 81 as the transfer belt 71 travels, and the transfer belt 7 is transferred to the sheet S.
After the attraction force with 1 is weakened, it is peeled from the transfer belt 71 by the peeling claw 82. And the heat fixing device 2
The toner image on the sheet is fixed by being conveyed to No. 1 and being heated and pressed there. On the other hand, the transfer belt 71 is discharged by the belt discharge corotrons 83 and 84, cleaned by the cleaner 13, and then conveys the sheet S supplied through the registration gate 77.

Also in this case, the gears according to the present invention are used not only to drive the photoconductor drums 9Y, 9M, 9C and 9K which are image carriers, but also to drive the transfer belt 71 which conveys the sheet. A transmission device can be used. Although the above example relates to a multicolor image forming apparatus, it is also possible to apply the gear transmission according to the present invention to a monochromatic image forming apparatus.

[0083]

As described above, according to the gear transmission of the present invention, the gear that transmits the rotation from the drive-side gear to the driven-side gear via the two gears that are coaxially provided. In the transmission device, it is possible to suppress the displacement shift of the driven body during rotation. Moreover, it is not necessary to provide an accessory such as a vibration absorber or an inertial load for damping or suppressing the speed fluctuation in the gear transmission device, which can prevent an increase in manufacturing cost and an increase in size of the device. . Further, according to the configuration of the second aspect, it is possible to achieve the above effect simply and quickly. Also,
As described in claim 3 or 4, by providing such a gear transmission device in the image forming apparatus, it is possible to suppress image shift and form a highly accurate image.

[Brief description of drawings]

FIG. 1 shows a gear transmission that is a premise of the present invention, (A) is a perspective view thereof, and (B) is a plan view thereof.

FIG. 2 is a graph showing a change in rotation speed caused by meshing between a first gear 1 and a third gear 3 in FIG.

FIG. 3 is a graph showing a change in rotation speed caused by meshing between a fourth gear 4 and a second gear 2 in FIG.

FIG. 4 is a graph showing a result of measuring a temporal variation of a rotation speed of a second rotation shaft A2 that is a driven shaft in the first embodiment of the present invention.

5 is a graph showing a result of measuring a temporal variation of a component forming the deviation of the rotation speed shown in FIG.

FIG. 6 is a graph showing a result of measuring a temporal change in displacement deviation of the second rotation axis A2 in the rotation direction in the first embodiment of the present invention.

FIG. 7 is a graph showing a result of measuring a temporal change of a component forming the displacement shift shown in FIG.

FIG. 8 is a graph showing a result of measuring a temporal change in the rotation speed of the second rotation axis A2 in a comparative example.

9 is a graph showing a result of measuring a temporal variation of a component forming the deviation of the rotation speed shown in FIG.

FIG. 10 is a graph showing a result of measuring a temporal change in displacement deviation of the second rotation axis A2 in the rotation direction in the comparative example.

FIG. 11 is a graph showing a result of measuring a temporal variation of a component forming the displacement shift shown in FIG.

FIG. 12 is a graph showing a result of analyzing a rate of displacement per unit time for each displacement deviation in the first embodiment.

FIG. 13 is a graph showing a result of analyzing a ratio of displacement per unit time for each displacement shift in the comparative example.

FIG. 14 is a graph showing a result of measuring a temporal change in the rotation speed of the second rotation axis A2 in another comparative example.

FIG. 15 is a graph showing a result of measuring a temporal variation of a component forming the deviation of the rotation speed shown in FIG.

FIG. 16 is a graph showing a result of measuring a temporal change in displacement deviation of the second rotation axis A2 in the rotation direction in the comparative example.

FIG. 17 is a graph showing a result of measuring a temporal change of a component forming the displacement shift shown in FIG.

FIG. 18 is a front view showing a meshed state of the gear transmission of the embodiment.

FIG. 19 (A) shows a structure of the first gear 1 in FIG.
Shows the speed fluctuation due to the meshing between the gear and the third gear 3, (B)
Shows the speed fluctuation due to the meshing of the second gear 4 and the fourth gear 4.

20 is a front view showing a state in which one tooth T ₁₁ of the first gear 1 actually starts meshing with one tooth T ₃₁ of the third gear 3 in FIG. 18. FIG.

FIG. 21 is a front view showing a state in which one tooth T ₁₁ of the first gear 1 actually terminates meshing with one tooth T ₃₁ of the third gear 3 in FIG.

FIG. 22 is a front view showing a modified example of the first embodiment.

FIG. 23 shows a gear transmission that is a premise of the second embodiment of the present invention, (A) is a perspective view thereof, and (B) is a plan view thereof.

FIG. 24 is a graph showing a result of measuring a temporal change in the rotation speed of the second rotating shaft A2 that is the driven shaft in the second embodiment of the invention.

FIG. 25 is a graph showing a result of measuring a temporal variation of a component forming the deviation of the rotation speed shown in FIG. 24.

FIG. 26 is a graph showing a result of measuring a temporal change in displacement deviation of the second rotation axis A2 in the rotation direction in the second embodiment of the invention.

FIG. 27 is a graph showing a result of measuring a temporal change of a component forming the displacement shift shown in FIG. 26.

FIG. 28 is a graph showing the result of analyzing the ratio of displacement per unit time for each displacement deviation in the second embodiment.

FIG. 29 is a front view showing an example of an image forming apparatus to which the gear transmission according to the present invention can be applied.

FIG. 30 is a front view showing another example of the image forming apparatus to which the gear transmission according to the present invention can be applied.

FIG. 31 is a front view showing another example of an image forming apparatus to which the gear transmission according to the present invention can be applied.

FIG. 32 is a front view showing another example of the image forming apparatus to which the gear transmission according to the present invention can be applied.

[Explanation of symbols]

M motor, 1st gear, 2 2nd gear,
3 3rd gear, 4 4th gear, 5 5th gear,
6 6th gear, A1 1st rotating shaft, A2 2nd
Rotating shaft, A3 third rotating shaft, A4 fourth rotating shaft, VA rotational speed deviation component caused by meshing of the first gear 1 and the third gear 3, VB second gear 2 and fourth Component of rotational speed caused by meshing with the gear 4 of
VC Rotational speed deviation component caused by meshing between the fifth gear 5 and the sixth gear 6, DA Displacement deviation component caused by meshing between the first gear 1 and the third gear 3, DB Second
Displacement component caused by meshing between the second gear 4 and the fourth gear 4, DC displacement component caused by meshing between the fifth gear 5 and the sixth gear 6, P _A first gear 1 pitch point of the third gear 3, the contact of the P _B pitch point of the second gear 2 and the fourth gear 4, the contact start point of the Q _A1 teeth T ₁₁ and the teeth T _31, Q _A2 teeth T ₁₁ and the teeth T ₃₁ End point, T ₁₁ one tooth of the first gear 1, T ₂₁ one tooth of the second gear 2, T ₃₁ one tooth of the third gear 3, T ₄₁ one tooth of the fourth gear 4. , O ₃ Gears 3, 4 center point, 9
Photoconductor drum (image carrier), 12 transfer drum (conveying means), 15 transfer corotron (transfer means), 37
Transfer belt (image carrier), 40 secondary transfer roll (transfer means, transport means), 64 registration roll (transport means), 9Y, 9M, 9C, 9K photoconductor drum (image carrier), 71 transfer belt (Conveying means),
80Y, 80M, 80C, 80K Corotron for transfer (transfer means)

Claims (4)

[Claims] 1. A first gear connected to the drive source side, a second gear connected to the driven body side, a third gear meshed with the first gear, and the third gear. And a fourth gear that is mounted coaxially with the second gear and that is meshed with the second gear, wherein one of the third gear and the fourth gear has an odd number of teeth of the other. And the timing at which the variation of the rotation speed of the gear due to the meshing of the first gear and the third gear reaches a maximum value, and the second gear
The gear transmission device is characterized in that the timing at which the variation of the rotational speed of the gear due to the meshing of the gear of No. 4 and the fourth gear becomes the maximum value substantially coincides with each other. 2. The meshing ratio between the first gear and the third gear and the meshing ratio between the second gear and the fourth gear are approximately 1.5, and On the pitch point of meshing with the third gear, when one tooth of the first gear contacts and presses one tooth of the third gear, One tooth of the fourth gear is in contact with and presses one tooth of the second gear at a pitch point of meshing with the fourth gear. The gear transmission according to claim 1. 3. The gear transmission according to claim 1, an image carrier that is connected to the second gear as the driven body and has a visible image formed on the surface thereof, and a conveying unit that conveys a sheet. An image forming apparatus comprising: a transfer unit configured to transfer a visible image on the image carrier to a sheet conveyed by the conveying unit. 4. The gear transmission according to claim 1, a movable image carrier on which a visible image is formed, and a driven body which is connected to the second gear and conveys a sheet. An image forming apparatus comprising: a conveying unit; and a transfer unit that transfers a visible image on the image carrier to a sheet conveyed by the conveying unit.