JP2018124328A - Drive transmission device and image forming apparatus including drive transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive transmission device that can cancel slippage and belt vibration at a peeling part that are the problems unique to a drive transmission system using a belt and pulley not engaged with each other for achieving low vibration and low noise.SOLUTION: In a drive transmission using a belt and pulley not engaged with each other, voltage is applied between the belt and pulley to generate an electrostatic attraction force and thereby increase a frictional force. A pressing member is provided at a position where the belt is separated from the pulley to reduce belt vibration generated between the belt and pulley and thereby reduce noise.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a drive transmission device used in an image forming apparatus and the like, and more particularly to an improvement of a drive transmission device using a belt and a pulley that do not mesh.

  2. Description of the Related Art Conventionally, in various apparatuses including an image forming apparatus, a drive transmission device that transmits a rotational force of a drive source such as a motor to a driven part is provided. For example, the image forming apparatus employs a configuration in which a driving force of a motor as a driving source is transmitted to a driving roller that drives a photosensitive drum or an intermediate transfer belt as a driven portion via a gear. However, in this configuration, vibration is generated by the rotation transmission error (particularly the meshing transmission error) between the gear to which the driving force is input (drive input gear) and the output gear (the driven gear) as a vibration force. To do. The vibration generated in the gear may be transmitted to gear support members such as shafts, bearings, and side plates, and may generate a large noise.

  Therefore, instead of the gear, a driving pulley and a driven pulley and a belt wound around them (a so-called flat belt) are used, and the rotational driving force of the motor is converted to a belt by utilizing the frictional force between the pulley and the belt. The structure to transmit to is being studied. However, if a large driving force is transmitted in this configuration, a slip occurs between the pulley and the belt, and the driving force of the motor may not be transmitted to the driven part.

  Therefore, a technique is known in which the pulley and the belt are electrostatically adsorbed to suppress slippage between the pulley and the belt (Patent Document 1). In this technology, by applying a bias to the core of the driving roller as a pulley, an electrostatic adsorption force acts between the driving roller and the intermediate transfer belt, and the driving force of the driving roller is transmitted to the intermediate transfer belt. doing.

JP-A-8-146783

  However, the above prior art has the following problems. In the technique of Patent Document 1, since an electrostatic attraction force is applied only between the driving roller (pulley) and the intermediate transfer belt, a plurality of rollers (in addition to the driving roller) that stretch the intermediate transfer belt ( There is a risk of slippage between the driven roller) and the intermediate transfer belt.

  In particular, when considering a configuration in which the driven part is driven by the driven roller, if the driven part has a large load, slippage between the driven roller and the belt is likely to occur. That is, in the configuration of Patent Document 1, since slip occurs between the belt and the driven roller, there is a problem that the rotational force of the driving source cannot be transmitted to the driven part with high accuracy. In the technique of Patent Document 1, since a bias is applied to the core of the driving roller and the intermediate transfer belt is polarized, an electrostatic adsorption force is generated between the driving roller and the intermediate transfer belt. It was difficult to generate a large adsorption force.

  Further, in Patent Document 1, when the intermediate transfer belt is peeled off, the intermediate transfer belt vibrates due to uneven adsorption force and load fluctuation, and noise is generated. In particular, when the electrostatic attraction force is increased, the non-uniformity of the attraction force becomes relatively large, so that there is a problem that noise due to belt vibration also increases.

  The present invention has been made in order to solve the above-described problems of the prior art, and its purpose is to transmit the rotational force of the drive source to the driven part with high accuracy, and to generate vibrations generated by driving the drive source. It is to reduce noise.

In order to solve the above problems, a drive transmission device of the present invention includes a drive source,
A driving pulley, a driven pulley connected to the driven part, and a belt wound around the driving pulley and the driven pulley, and transmitting the rotational force of the driving source to the driving pulley, the belt and the belt In the drive transmission device that transmits driving to the driven part via a driven pulley, at least one of the driving pulley and the driven pulley has a conductive layer, and the pulley having the conductive layer and the belt pass through a dielectric layer. And a voltage applying means for applying a potential difference between the conductive layer of the pulley having the conductive layer and the belt, wherein the drive transmission device includes at least one pressing member. And the pressing member is arranged to contact the pulley having the conductive layer through the belt, and the belt is peeled off from the pulley when a predetermined voltage and load are applied. The pressing member to rotate the downstream side of a position, characterized in that installed.

  According to the present invention, in a drive transmission device using pulleys and belts that do not mesh with each other, it is possible to generate a frictional force necessary for driving force transmission, and to perform drive transmission without causing slippage. Further, since there is no meshing, generation of vibration can be suppressed, image deterioration such as unevenness can be prevented, and noise generated from the drive transmission device can be greatly reduced. Furthermore, with a simple configuration in which the pressing member is installed in the peeling portion, it is possible to suppress the vibration of the belt in the peeling portion and reduce noise.

The figure explaining the drive transmission device using the electrostatic attraction force of Example 1. Configuration diagram of image forming apparatus Configuration diagram of the image forming unit Sectional view, side view of FIG. FIG. 4 is a circuit diagram for part A and a diagram for explaining the electrical equivalent circuit of FIG. The figure explaining the relationship between the applied voltage and the drive force which can be transmitted in the drive transmission apparatus of 1st Embodiment Diagram explaining the mechanism of noise generation at the peeling part The figure explaining the noise reduction effect by a pressing member The figure explaining the drive transmission device using the electrostatic attraction force of Example 2.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that members, numerical values, materials, and the like used in the description are merely examples for the purpose of assisting understanding, and are not intended to limit the present invention.

[Example 1]
First, the basic configuration and operation of the image forming apparatus including the drive transmission apparatus according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 2 is an explanatory diagram of the basic configuration of the image forming apparatus. As shown in FIG. 2, the image forming apparatus 100 according to the first embodiment is a full-color laser beam printer in which yellow, magenta, cyan, and black image forming portions PY, PM, PC, and PK are arranged along the intermediate transfer belt 9. is there.

  In the image forming unit PY, a yellow toner image is formed and carried on the photosensitive drum 1Y that is rotationally driven, and then is primarily transferred to the intermediate transfer belt 9 by the primary transfer roller 5Y in the first transfer unit TY. Similarly, in the image forming portions PM, PC, and PK, magenta toner images, cyan toner images, and black toner images are formed on the photosensitive drums 1M, 1C, and 1K, and are sequentially superimposed and primarily transferred to the intermediate transfer belt 9.

  The intermediate transfer belt 9 is supported around the drive roller 13, the tension roller 12, and the backup roller 10, and rotates in the arrow B direction as the drive roller 13 rotates. The intermediate transfer belt 9 is stretched upward in the figure by primary transfer rollers 5Y to 5K, and first transfer portions TY to TK are formed between the photosensitive drums 1Y to 1K.

  The toner image transferred from each image forming unit and carried on the intermediate transfer belt 9 is conveyed to the secondary transfer unit T2 as the intermediate transfer belt 9 rotates, and is secondarily transferred to the recording material P. The recording material P is drawn from the paper feed cassette 19 by the paper feed roller 14, separated one by one by the separating device 15, and sent to the registration roller 16. The registration roller 16 feeds the recording material P to the secondary transfer portion T <b> 2 by aligning the head with the toner image carried on the intermediate transfer belt 9. The recording material P onto which the toner image has been secondarily transferred is transferred to the fixing device 17 and subjected to heat and pressure, whereby the image is fixed on the surface.

The intermediate transfer belt cleaning device 18 is installed so as to be in contact with and separated from the intermediate transfer belt 9 by a driving source (not shown). During normal printing, the intermediate transfer belt cleaning device 18 comes into contact with the intermediate transfer belt 9 and removes transfer residual toner remaining on the intermediate transfer belt 9 after passing through the secondary transfer portion T2. During the laser light quantity adjustment mode and transfer voltage adjustment mode operation that do not involve transfer of the toner image to the intermediate transfer belt 9, the intermediate transfer belt cleaning device 18 is separated from the intermediate transfer belt 9 in order to prevent the deterioration of the intermediate transfer belt 9. The
Next, the details of the image forming unit will be described with reference to FIG.

  The image forming units PY, PM, PC, and PK are configured similarly except that the toners used in the attached developing devices 4Y, 4M, 4C, and 4K are different from yellow, magenta, cyan, and black. Accordingly, in the following description, the yellow image forming unit PY will be described, and the image forming units PM, PC, and PK will be described by replacing Y at the end of the symbol of the configuration to be described with C, M, and K.

  FIG. 3 is an explanatory diagram of the configuration of the image forming unit, the primary transfer unit, and the secondary transfer unit. As shown in FIG. 3, the image forming unit PY includes a charging device 2Y, an exposure device 3Y, a developing device 4Y, a primary transfer roller 5Y, and a cleaning device 6Y around the photosensitive drum 1Y.

  The photosensitive drum 1Y is configured by applying an organic photoconductor layer having a negative polarity on the outer peripheral surface of an aluminum cylinder, and rotates in the direction of arrow A. The charging device 2Y receives a negative voltage from the power source D3 and irradiates the surface of the photosensitive drum 1Y with charged particles, thereby charging the surface of the photosensitive drum 1Y to a uniform negative potential. The exposure device 3Y scans the surface of the photosensitive drum 1Y with a laser beam that is ON-OFF modulated in accordance with scanning line image data obtained by developing a yellow color separation image with a rotating mirror. Thereby, an electrostatic image corresponding to the image data is formed on the surface of the charged photosensitive drum 1Y.

  The developing device 4Y stirs a two-component developer obtained by mixing a magnetic carrier with toner and charges the toner negatively. The charged toner is carried on the developing sleeve 4s rotating around the fixed magnetic pole 4j in the counter direction with the photosensitive drum 1Y, and rubs against the photosensitive drum 1Y. The power source D4 applies a developing voltage obtained by superimposing an AC voltage to a negative DC voltage to the developing sleeve 4s, and causes the toner to adhere to the electrostatic image of the photosensitive drum 1Y that has a relatively positive polarity relative to the developing sleeve 4s. Then, the electrostatic image is developed as a toner image.

  The primary transfer roller 5Y sandwiches the intermediate transfer belt 9 between the photosensitive drum 1Y and forms a primary transfer portion TY between the photosensitive drum 1Y and the intermediate transfer belt 9. The power source D1 applies a positive DC voltage to the primary transfer roller 5Y, and negatively charges the toner image carried on the photosensitive drum 1Y to the intermediate transfer belt 9 passing through the primary transfer portion TY. Let The cleaning device 6Y slides the cleaning blade against the photosensitive drum 1Y to remove the transfer residual toner that has passed through the primary transfer portion TY and remained on the surface of the photosensitive drum 1Y.

  The secondary transfer roller 11 is in pressure contact with the backup roller 10 via the intermediate transfer belt 9, and forms a secondary transfer portion T <b> 2 between the intermediate transfer belt 9 and the secondary transfer roller 11. The secondary transfer portion T2 sandwiches and conveys the recording material P superimposed on the toner image on the intermediate transfer belt 9, and the recording material P passes from the secondary transfer portion T2 to the recording material P in the process of passing the secondary transfer portion T2. The toner image is secondarily transferred.

  The power source D <b> 2 applies a positive DC voltage to the secondary transfer roller 11, and causes a transfer current to flow through the series circuit of the backup roller 10, the intermediate transfer belt 9, the recording material P, and the secondary transfer roller 11. The transfer current is involved in the movement of toner from the intermediate transfer belt 9 to the recording material P.

  Hereinafter, the overall configuration of the drive transmission device 50 of this embodiment will be described with reference to FIG. FIG. 1 is a perspective view of the drive transmission device 50. The drive transmission device 50 increases the drive force that can be transmitted by electrostatically attracting the pulley and the belt.

  In the present embodiment, the rotational shaft 30K of the photosensitive drum 1K that is rotationally driven by transmission of the rotational driving force of the drive source by the drive transmission device 50 is illustrated, and the motor 20 is illustrated as the drive source. When the drive transmission device 50 is applied to the image forming apparatus 100, as an example of the driven part, a component that rotates and performs an operation related to image formation is suitable. A driving roller 13 for driving the belt 9 and a fixing roller in the fixing device 17 are suitable. However, the present invention is not limited to these, and is suitable for any place that requires drive transmission, such as application to drive distribution.

  As shown in FIG. 1, the drive transmission device 50 includes a drive pulley 21, a driven pulley 22, an endless belt 23, a voltage applying unit 24, and a pressing member 36. A driving force is transmitted to the belt 23 by a frictional force on a contact surface between the driving pulley 21 and the belt 23. When the driving force is transmitted to the belt 23 and the belt 23 rotates, the driving force is transmitted to the driven pulley 22 by the frictional force at the contact surface between the belt 23 and the driven pulley 22. Since the driven pulley 22 and the photosensitive drum 1K are connected via the rotating shaft 30K, the driving force of the driven pulley 22 is transmitted to the photosensitive drum 1K.

  As shown in FIG. 1, the voltage applying means 26 gives a potential difference between the conductive layer 21 of the driving pulley 21 and the belt 23 via the conductive brushes 28a and 28c. Then, an electrostatic attraction force is generated between the drive pulley 21 and the belt 23. Further, an electrostatic attraction force is generated between the driven pulley 22 and the belt 23 with the same configuration as the driving pulley 21.

  As shown in FIG. 1, the pressing member 36 installed at the peeling portion on the side of the drive pulley 21 has a shaft 35 at the center, and the shaft is pressed in a direction perpendicular to the shaft by a compression spring 37, and has a constant contact. Held by pressure. The conductive pressing member 36 reduces vibration and noise generated when the belt 23 is peeled off from the drive pulley 21. This will be described in detail later.

  Hereinafter, the drive force that can be transmitted by the drive transmission device 50 will be described. First, each component of the drive transmission device 50 will be described with reference to FIGS. 4 (a) and 4 (b). 4A is a cross-sectional view taken along the line XX in FIG. 1, and FIG. 4B is a cross-sectional view taken along the line YY in FIG. 4A. The drive pulley 21 has a cylindrical shape having a conductive layer 21 to which a voltage can be applied, and is coupled to the output shaft 20a of the motor 20 via an insulating member 34a. The drive pulley has a radius of 10 mm and a width of 10 mm. Like the drive pulley 21, the driven pulley 22 has a cylindrical shape having a conductive layer to which a voltage can be applied, and is coupled to the shaft 30K via an insulating member 34b.

The shaft 30K is connected to the photosensitive drum 1K. The radius of the driven pulley 22 is 40 mm and the width is 10 mm. The pressing member 36 is conductive and cylindrical, and has a radius of 10 mm and a width of 10 mm. The pressing member 36 is coupled to a pressing member shaft 35, and the pressing member shaft 35 is biased by a compression spring 37. The compression spring 37 presses the pressing member 36 in a direction perpendicular to the axis of the drive pulley 21 and brings the pressing member 36 into contact with a predetermined position.
A DC voltage is applied to the conductive layer of the driving pulley 21 and the conductive layer of the driven pulley 22 from the voltage applying means 24 and 26 via the conductive brushes 28a and 28b.

  The endless belt 23 has a two-layer structure having a dielectric layer 23a on the side in contact with the pulley and a conductive layer 23b on the outer side. The dielectric layer 23a is made of a polyimide resin material in which conductive carbon is dispersed, the volume resistivity is adjusted to about 1E9 to 1E14 Ω · cm, the thickness is about 70 μm, and the width is about 10 mm. The conductive layer 23b is formed by sputtering of Ni and has a thickness of about 100 nm. Further, the width of the conductive layer 23b of the endless belt 23 is narrower than the width of the dielectric layer 23a, and the creepage distance from the pulley surface is increased to prevent discharge. The winding angle between the endless belt 23 and the driving pulley 21 is 120 °, and the winding angle between the endless belt 23 and the driven pulley 23 is 240 °.

  With the configuration described above, an electrostatic attraction force is generated between the drive pulley 21 and the driven pulley 22 and the endless belt 23, and the frictional force required for drive transmission is increased. Note that the initial tension applied to the endless belt 23 may be small, and is 0.5 kgf here.

  Next, the electrostatic attraction force generated between the belt and the pulley used to increase the drive force that can be transmitted by the drive transmission device 50 will be described with reference to FIG. FIG. 5A is a diagram schematically showing a micro-contact state between the drive pulley 21 and the endless belt 23 in part A of FIG. 4B, and FIG. 5B is an electric diagram of the drive transmission device 50. It is the equivalent circuit diagram which showed the physical property.

  As shown in FIG. 5A, since the driving pulley 21 and the endless belt 23 are in contact with each other with minute irregularities, there is a minute gap between the driving pulley 21 and the endless belt 23. Is formed. This minute contact state is electrically expressed by an equivalent circuit as shown in FIG. Here, Cb1 is the capacitance component of the dielectric layer 23a, Rb1 is the resistance component of the dielectric layer 23a, Cg1 is the capacitance of the gap formed by the drive pulley 21 and the endless belt 23, and Rg1 is the drive pulley 21 and the endless belt. 23 contact resistance.

  When a voltage is applied between the conductive layer 23b and the driving pulley 21 with such a configuration, charges are accumulated in Cg1 according to the magnitude of each capacitance and resistance, and as a result, an electrostatic adsorption force is generated. In particular, when Rb1 is small, a large electrostatic attraction force such as a Johnsen-Rahbek force is generated.

  An overall equivalent circuit of the drive transmission device 50 is as shown in FIG. FIG. 5B is obtained by adding an electrostatic capacitance component and a resistance component due to the driven pulley 22 and the endless belt 23 to the equivalent circuit of FIG. Again, charges are accumulated in Cg1 and Cg2 according to the applied voltage, each capacitance, and the resistance, and electrostatic force is generated between the drive pulley 21 and the driven pulley 22 and the conductive layer 23b of the endless belt 23. Generated and electrically adsorbed.

  As a result of the electrostatic attraction force generated in this way, the vertical drag between the endless belt 23 and the drive pulley 21 and the driven pulley 22 is increased to increase the frictional force. It can be increased.

  Next, a description will be given of an increase in the transmission force that can be transmitted by the action of the electrostatic attraction force generated by applying a voltage. When drive transmission is performed by a belt, a difference occurs in belt tension before and after the pulley is applied by the rotational driving force of the driving pulley, and the driving force is transmitted to the driven pulley by this tension difference. The transmitted driving force is equal to this tension difference.

In such drive transmission, the transmittable driving force, that is, the tension difference that can be generated, depends on the maximum frictional force that can be generated between the pulley and the belt. In general, in belt drive transmission without using electrostatic attraction force, the transmittable drive force F ₁ is expressed by the following equation (1) from Euler's formula.

In Equation (1), T is a tension that applies tension to the belt, θ is a winding angle of the belt around the pulley, and μ is a coefficient of friction between the belt and the pulley.
Further, when the electrostatic attraction force is applied, the transmittable driving force F ₂ is expressed by the following equation (2), where P is the electrostatic attraction force per unit area, r is the radius of the pulley, and b is the width of the belt. It is represented by

That is, the increase ΔF of the drive force that can be transmitted due to the addition of the electrostatic attraction force is the difference between F ₂ and F ₁ and is expressed by the following equation (3).

Here, the electrostatic attraction force P ₁ per unit area generated between the drive pulley 21 and the endless belt 23 in this embodiment can be considered as a force acting between the electrodes of the capacitor, and is expressed by the following equation (4). The

In Expression (4), ε is a dielectric constant of the conductive layer 23 a of the endless belt 23, d is a thickness, and V ₁ is a voltage applied between the drive pulley 21 and the conductive layer 23 b of the endless belt 23. Therefore, the driving force that can be transmitted from the driving pulley 21 to the endless belt 23 is obtained by substituting the equation (4) into the equation (3), and the transmitting force that can be transmitted is secondary to the voltage applied between the pulley and the belt. It can be seen that it increases in proportion.

  Fig. 6 shows an example of the relationship between the applied voltage and the transmittable driving force calculated from the measurement results of the pulleys and belts actually fabricated. The experimentally increased transmittable driving force is proportional to the applied voltage in quadratic order. It has been confirmed that

  Now, the above description is about the transmission force that can be transmitted between the drive pulley 21 and the endless belt 23, but the transmission force that can be transmitted can be similarly calculated for the driven pulley 22. However, in the drive transmission device 50 of this embodiment, the driven pulley 22 and the drive pulley 21 have different belt winding angles θ and pulley radii r. In the driven pulley 22, the belt winding angle θ and the pulley radius r are larger than in the driving pulley 21, so that the driven pulley 22 has a larger contact area with the endless belt 23 than the driving pulley 21.

  Then, the electrostatic capacitance component in the equivalent circuit shown in FIG. 5B increases, and the electrostatic attraction force between the driven pulley 22 and the endless belt 23 increases. As a result, the driven pulley 22 can transmit more driving force than the driving pulley 21. In order to increase the drive force that can be transmitted by the drive pulley having a small diameter, a voltage larger than that of the driven pulley is applied to the drive pulley. Then, in the drive pulley, the suction force per unit area is larger than that in the driven pulley, and therefore belt vibration caused by unevenness of the suction force is increased in the drive pulley, and a larger noise is generated. In view of this, a pressing member is installed in a driving pulley that is noisy to suppress belt vibration.

A mechanism for generating vibration due to uneven adsorption force will be described with reference to FIG. FIG. 7A is a diagram schematically showing a state where the belt 23 is peeled from the drive pulley 21 in the drive transmission device 50 when no pressing member is installed. The belt 23 is indicated by a broken line for easy understanding of the mechanism. In this configuration, when a voltage is applied to the drive pulley 21 and the belt 23, an electrostatic adsorption force P works in the axial direction of the drive pulley 21. Further, the tension T acts in the direction where the belt 23 is separated from the driven pulley 22. The tension T can be expressed as Equation (5), where the initial tension T ₀ , the winding angle θ, and the friction coefficient between the pulley and the belt are μ.

  From a macro perspective, it appears that a uniform electrostatic attraction force P is working, but from a micro perspective, the attraction force is affected by variations in the film thickness of the conductive layer 23a of the belt 23 and the effects of surface irregularities. Is working unevenly. Therefore, there are times when the electrostatic attraction force P is minimum or maximum.

  Next, the position where the belt 23 peels from the drive pulley 21 will be described. In any case, the belt 23 does not peel at the position e where the common tangent line of the driving pulley 21 and the driven pulley 22 is in contact with the driving pulley 21 when the electrostatic attraction force P is working. This is because the tension T acts in a direction orthogonal to the electrostatic attraction force P, so there is no force opposite to the electrostatic attraction force P.

  Therefore, the belt 23 is wound around the drive pulley 21, but in the case of the downstream side from the position e, a component force of the tension T is generated as a force opposed to the electrostatic adsorption force P. Since this component force increases as the wrapping angle increases, peeling occurs at the downstream b point as the maximum electrostatic attraction force is applied, and at the most upstream a point when the minimum electrostatic adsorption force is applied. I understand that The distance between a and b, that is, the gap c at the peeling position becomes the vibration amplitude of the belt 23, and the vibration and noise increase as the gap increases.

  A location where the pressing member 36 is installed will be described. From the mechanism described above, in order to reduce the vibration and noise of the belt 23, it is understood that it is important to reduce the amplitude of the belt vibration, that is, to reduce the gap c at the peeling position. Placing the pressing member 36 downstream of the peeling position a at the minimum electrostatic attraction force has an effect of reducing vibration and noise. FIG. 7B illustrates the case where the pressing member 36 is placed downstream of the peeling position a at the minimum electrostatic attraction force, that is, when the contact point between the pressing member 36 and the driving pulley 21 is at the position d. Is.

  When there is a contact point d between the pressing member and the drive pulley at a place as shown in the figure, the gap c ′ between the peeling position b and the maximum electrostatic attraction force is smaller than the gap c at the peeling position in FIG. doing. In the present invention, the pressing member 36 is installed on the downstream side from the position where the belt 23 peels from the drive pulley 21 when a predetermined voltage and load are applied. For example, the peeling position at the minimum electrostatic attraction force can be easily checked by the following method. First, in a configuration in which the pressing member 36 is not shown in FIG. 1, a displacement meter is installed at a position where the belt 23 is attracted, a predetermined adsorption force and load are applied, and the belt is driven at a low speed.

  At the position e in FIG. 7A, the belt 23 and the pulley 21 are always adsorbed, so that the displacement meter hardly changes. Shift the displacement meter to a position slightly downstream of rotation, and observe the change of the displacement meter in the same way. When the displacement meter reaches the peeling position a at the minimum electrostatic attraction force, unlike the previous case, the amplitude of the measured value of the displacement meter changes. Further, when the displacement meter is shifted downstream, the amplitude of the measured value of the displacement meter becomes maximum at the peeling position at the maximum electrostatic attraction force. In this way, it is possible to measure the peeling position at the minimum electrostatic attraction force and the maximum electrostatic attraction force, and the pressing member is arranged at a position downstream of the peeling position a at the minimum electrostatic attraction force. Thus, noise can be reduced.

  FIG. 8 shows experimental results for verifying the effects of the present invention. The experiment was carried out with the drive transmission device shown in FIG. 1, the suction speed was generated at 700 rpm, the applied voltage was 700 V, a microphone was installed at a distance of 10 cm from the peeling position of the drive pulley, and the noise was measured. . The recorded sound was corrected with an A characteristic filter, and OA (dB) from 200 to 5 kHz was calculated. FIG. 8 shows background noise and noise data with and without a member. It can be seen that the noise without the pressing member 36 is about 3 dB larger than the background noise. On the other hand, it was found that the noise when the pressing member 36 was placed was about the same level as the background noise, and the effect of reducing the peeling sound was shown.

  The drive transmission device of the present invention is not limited to the configuration described so far, and can be suitably implemented with other configurations. Moreover, it is good also as a structure which has an endless belt only as a conductive layer and has a dielectric layer on the pulley surface, and the structure which has a dielectric layer in both a belt and a pulley. Further, the endless belt is not limited to a flat belt, and may be a V belt, a V rib belt, or the like that transmits friction with a pulley.

  Further, the size, shape, and supporting method of the pressing member 36 in FIG. 1 are not limited to the configuration described so far, and other configurations can be implemented. The diameter of the pressing member is not limited to 10 mm, and may be smaller or larger. The shape is not limited to the roller shape, but may be a blade shape or a crown shape. However, when the ground is conductive, it is better to make the width of the pressing member narrower than that of the dielectric layer 23a in order to suppress the occurrence of discharge between the pressing member and the pulley. The support method is not limited to a spring, and any support method may be used as long as it is in contact with a predetermined peeling position. The number of pressing members is not limited to one, and may be placed on both the driving pulley and the driven pulley. When there are three or more pulleys, there may be three pressing members.

[Example 2]
A second embodiment of the present invention will be described. The present embodiment is an image forming apparatus similar to that of the first embodiment, and is different from the first embodiment in the configuration relating to the voltage application method and the configuration in which the pressing member is insulated from the power source in the drive transmission device provided. Here, only the difference will be described, and detailed description regarding other parts will be omitted.

  First, with reference to FIG. 9, the structure of the drive transmission apparatus in Example 2 is demonstrated. FIG. 9A is a side view of the drive transmission device 50 and schematically shows applied voltages. FIG. 9B is a diagram showing FIG. 9A as an electrical equivalent circuit.

  As shown in FIG. 9A, in the configuration of the applied voltage in the second embodiment, the drive pulley 21 is grounded, the voltage is applied to the driven pulley 22, and the conductive layer 23b of the endless belt 23 is floated. The difference from the first embodiment is that the drive pulley 21 is grounded and the endless belt 23 is floated. The drive pulley 21 is electrically connected to the shaft 20a and is grounded through the shaft 20a. The pressing member 36 is made of an insulating material, insulated from the voltage applying means 24, and configured not to have a potential difference from the conductive layer of the belt 23.

  Here, the electrical configuration of the first embodiment is referred to as a parallel configuration, and the electrical configuration of the second embodiment is referred to as a series configuration. With such a series configuration, the conductive layer 23 b of the endless belt 23 becomes an intermediate potential between the potentials of the driving pulley 21 and the driven pulley 22. Then, a potential difference is generated between the driving pulley 21 and the endless belt 23, and the driven pulley 22 and the endless belt 23, and an electrostatic adsorption force is generated between each pulley and the endless belt 23. Slip of the belt 23 is suppressed.

  Also in the drive transmission device 50 of the present embodiment, the transmittable drive force can be calculated from the electrostatic attraction force as in the first embodiment. However, in the parallel configuration of the first embodiment, the transmittable driving force is reduced by the drive pulley 21 having a small diameter, but in the serial configuration of the present embodiment, the transmittable driving force is decreased by the driven pulley 22 having a large diameter. The reason will be described below.

The driven pulley 22 and the drive pulley 21 differ in belt winding angle θ, pulley radius r, and voltage V applied between the pulley and the belt, and therefore the transmittable driving force is different. In the driven pulley 22, the belt winding angle θ and the pulley radius r are larger than those in the driving pulley 21. On the other hand, since the driven pulley 22 has a larger contact area with the endless belt 23 than the driving pulley 21, the resistance component in the equivalent circuit shown in FIG. 9B is reduced, and the voltage V applied between the pulley and the belt is Get smaller. That is, V ₁ > V ₂ in FIG.

  As described above, the transmittable driving force depends on the voltage V applied between the pulley and the belt. For this reason, the drive force that can be transmitted is more affected by a decrease in the voltage V between the pulley and the belt than when the winding angle θ and the pulley radius r are increased, and the driven pulley 22 is more driven than the drive pulley 21. Becomes smaller.

  Thus, since the voltage applied between the drive pulley and the belt is larger than the voltage applied between the driven pulley and the belt, the electrostatic adsorption force per unit area is increased by the drive pulley. As a result, the vibration of the belt due to the unevenness of the suction force is increased by the drive pulley, and a larger noise is generated. In view of this, a pressing member is installed in a driving pulley that is noisy to suppress belt vibration. With this configuration, the noise reduction effect was obtained in the present embodiment as well as in the first embodiment.

  Further, the drive transmission device of the present invention is not limited to the configuration described so far, and can be implemented in other configurations. Specifically, a configuration in which a voltage is applied to the drive pulley to ground the driven pulley, and the drive pulley and the driven pulley each have two electrodes with different potential differences through an insulating layer in the circumferential direction. The structure which generate | occur | produces adsorption | suction force may be sufficient.

1Y, 1M, 1C, 1K ... photosensitive drums 2Y, 2M, 2C, 2K ... charging devices 3Y, 3M, 3C, 3K ... exposure devices 4Y, 4M, 4C, 4K ... developing devices 4j .. Fixed magnetic pole 4s... Development sleeve 5Y, 5M, 5C, 5K... Primary transfer roller 6Y, 6M, 6C, 6K... Cleaning device 9. ..Secondary transfer roller 12 ... Tension roller 13 ... Drive roller 14 ... Feed roller 15 ... Separating device 16 ... Registration roller 17 ... Fixing device 18 ... Intermediate transfer belt Cleaning device 20 ... motor 21 ... driving pulley 22 ... driven pulley 23 ... endless belt 23a ... dielectric layer 23b ... conductive layer 24 ... voltage applying means 26 ... voltage applying means 8a, 28b, 28c ... conductive brushes 34a, 34b ... driven, drive roller bearing 35 ... pressing member shaft 36 ... pressing member 37 ... compression spring 50 ... drive transmission device 100- ..Image forming devices

Claims (10)

A driving source;
A driving pulley;
A driven pulley connected to the driven part;
A belt wound around the drive pulley and the driven pulley,
In the drive transmission device that transmits the rotational force of the drive source to the drive pulley and transmits the drive to the driven part via the belt and the driven pulley, a potential difference is generated between at least one of the pulley and the belt. An electrostatic belt drive transmission device using electrostatic attraction force
Having at least one pressing member;
The pressing member is disposed so as to contact the pulley to which a potential difference is applied via the belt, and the pressing member is disposed on the downstream side of the rotation from the position where the belt is separated from the pulley when a predetermined voltage and load are applied. Is an image forming apparatus. At least one of the pulley and the belt has a conductive layer, the pulley having the conductive layer and the belt are disposed so as to contact each other through a dielectric layer, and the conductive layer of the pulley having the conductive layer and the belt The electrostatic belt drive transmission device according to claim 1, further comprising: a voltage applying unit that applies a potential difference between the two. 3. The static pressure according to claim 1, wherein the pressing member is provided so as to come into contact with a pulley having a largest noise at a separation portion from the belt among the plurality of pulleys via the belt. Electric belt drive transmission device. 3. The electrostatic belt drive transmission device according to claim 1, wherein the pressing member is provided so as to come into contact with the smallest diameter pulley among the plurality of pulleys via the belt. 3. The electrostatic belt drive transmission device according to claim 1, wherein the pressing member is provided on a drive pulley so as to come into contact with the drive pulley via the belt. The electrostatic belt drive transmission device according to claim 1, wherein the plurality of pressing members are provided in contact with the plurality of pulleys via the belt, respectively. The electrostatic belt drive transmission device according to any one of claims 1 to 5, wherein the pressing member is conductive, and the width of the pressing member is narrower than a dielectric layer of the belt. 6. The electrostatic belt drive transmission device according to claim 1, wherein the pressing member is conductive, and power is supplied to the belt conductive layer via the pressing member. 7. The electrostatic belt drive transmission device according to claim 1, wherein the belt conductive layer and the pressing member have the same potential. 6. The electrostatic belt drive transmission device according to claim 1, wherein a direction in which the pressing member is pressed is a direction perpendicular to a pulley axis.