JP2006149130A - Rotor driving device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotor driving device that can heighten detection accuracy by reducing influence of fluctuations other than an arbitrary period, when the speed fluctuations of the arbitrary period is detected by measuring the passing time of a rotational speed detector for every section of detecting portions. <P>SOLUTION: This rotor driving device is provided with a driving source 1 whose rotational speed can be controlled from outside, transmission mechanism portions 3, 4 that transmit the rotating torque of the driving source, a rotational speed detecting means 15 that detects the rotational speed of a driven shaft that is driven by rotating torque transmitted from the transmission mechanism portions, and a control device 10 that controls the rotational speed of the driving source based on the rotational speed detected by the rotational speed detecting means. A rotating plate 7 provided with at least one or more detecting portions 9 as the rotational speed detecting means 17 and a detector 15 that detects the detecting portions 9 are provided. This rotating plate 7 is fastened via an elastic body 20 which can be displaced in the rotating direction of a subject-to-detection shaft 8. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rotator driving device and an image forming apparatus including the rotator driving device, and more particularly, in a rotator driving device that detects and corrects rotational fluctuations of a driven shaft connected by a drive source and a transmission mechanism. The present invention relates to a rotator driving device provided with a rotation speed detection means for improving the detection accuracy of a speed change in a cycle.

An encoder conventionally used as a rotation detector is provided with a large number of slits as detected parts on the circumference of the rotating plate, and counts the number of slits that have passed through the detector when the rotating plate is rotated. The amount of rotation (rotation speed) is detected. However, this method can detect a rotation error with high accuracy, but has an excessive amount of information. Therefore, when the frequency analysis is performed on the encoder output result, many components other than the speed fluctuation of an arbitrary period are measured.
As a conventional technique, Patent Document 1 discloses a technique in which translational vibration in the axial direction is blocked by providing elasticity only in the axial direction and detection accuracy at the slit plate is increased.
In Patent Document 2, when an encoder unit and a motor unit are coupled, an elastic body is used to adjust a torsional natural frequency so that it does not overlap with a mechanical natural frequency or a control system response frequency. A technique for reducing the detection error is disclosed.
Further, in Patent Document 3, the passage time is measured by a simple slit plate provided on the driven shaft, and then speed unevenness (amplitude and phase) in an arbitrary period is obtained by calculation, and the motor command value is set so as to suppress this. A technique that suppresses an arbitrary order component (for example, a primary component due to eccentricity or the like) with a low-cost configuration by calculating and correcting and controlling is disclosed.
Japanese Utility Model Publication No. 5-94711 JP-A-8-251965 Japanese Patent Application No. 2004-129906

However, the prior art disclosed in Patent Document 1 can reduce the axial translational vibration component, but the rotational vibration component (gear meshing vibration, drive motor torque unevenness, drive shaft eccentricity, etc.). (Vibration) cannot be reduced and is transmitted to the detection unit as it is. Therefore, when detecting a fluctuation in speed of an arbitrary period (for example, a low-order component or a primary component having a high influence on the position error) There is a problem that rotational vibration (vibration component in the rotational direction) becomes a measurement error.
In addition, the conventional technique disclosed in Patent Document 2 has a problem in assembling because a plurality of parts including an inertia body called a ring and a spring are used to connect the motor and the encoder. Furthermore, there is a problem that the cost is increased by using an encoder with high resolution.
In addition, the conventional technique disclosed in Patent Document 3 detects the speed fluctuation of the periodic component with a simple slit plate without using an encoder with high resolution. The detection unit has a problem that a detection error occurs because vibration components in various rotation directions are superimposed.
In view of such a problem, the present invention includes a rotating plate provided with at least one detected portion as a rotation speed detecting means, and a detector for detecting the detected portion, and the rotating plate is used as a detection target shaft. By fastening through an elastic body that can be displaced in the rotational direction, when measuring the passage time of each detected section and detecting speed fluctuations in any period, the influence of fluctuations other than any period is reduced. An object of the present invention is to provide a rotating body drive device that can improve detection accuracy.

In order to solve such a problem, the present invention provides a drive source capable of controlling the rotational speed from the outside, a transmission mechanism portion for transmitting the rotational torque of the drive source, and transmission by the transmission mechanism portion. A rotational speed detecting means for detecting the rotational speed of the driven shaft driven by the rotational torque, and a controller for controlling the rotational speed of the drive source based on the rotational speed detected by the rotational speed detecting means. The rotational speed detection means includes a rotating plate including at least one or more detected parts, and a detector that detects the detected parts. It is fastened to the driven shaft via an elastic body that can be displaced in the rotational direction of the driven shaft.
In the present invention, a rotating plate having a detected part (for example, a slit) is provided on a rotating shaft on a driven shaft, a passing time is measured by a detector, and a speed fluctuation of an arbitrary period is calculated from this time. The speed reference signal is generated by the control unit so as to cancel the operation. In other words, in the present invention, since the time required for the detected part to pass the detector is measured, speed fluctuation detection of an arbitrary period is caused by the influence of a rotational vibration on the detected part other than an arbitrary period, particularly when high-order rotational vibration is applied to the detected part. Accuracy will be reduced. Therefore, in the present invention, in order to suppress higher-order rotational vibration, the rotating plate is fastened via an elastic body that can be displaced in the rotational direction of the driven shaft.
According to a second aspect of the present invention, the elastic body is constituted by a member having a hardness that transmits a frequency of a primary component or less and blocks a frequency of a secondary component or more.
The hardness of the elastic body of the present invention is set so as to transmit vibrations having an arbitrary period or less. In general, the vibration in rotation is large in the primary component due to the eccentric assembly or the like, and the primary component can be detected with high accuracy by blocking the secondary component or higher. Thereby, if correction control is performed using this detection result, highly accurate rotation drive can be performed.

According to a third aspect of the present invention, the elastic body is a spiral spring.
In the present invention, the elastic body is constituted by a spiral spring. If the spiral metal spring can be configured together with the sheet metal mold that manufactures the slit in the rotating plate, the slit portion and the elastic body are formed in an integrated structure, so that it is possible to prevent an increase in cost due to an increase in the number of parts and the elastic body. This can be done without increasing the assembly man-hours. In addition, since the translational vibration other than the rotation direction can be elastically deformed, higher-order translational vibration in the axial direction can also be blocked. This method can be made of the same material as that of the rotating plate and can be made of an elastic body, so that it is less susceptible to environmental temperature than resin and rubber, and can be used for a long time.
According to a fourth aspect of the present invention, the elastic body is rubber.
In the present invention, the elastic body is made of rubber. By using rubber between the rotating plate and the driven shaft, the assembling work can be simplified by utilizing the expansion and contraction of the rubber. In addition, rubber has higher viscosity than metal and can efficiently absorb higher-order rotation and translational vibration, so that the shape of the elastic body can be reduced and the structure can be made more compact, thus reducing the weight.
According to a fifth aspect of the present invention, the elastic body is a plurality of leaf springs.
In the present invention, the elastic body is constituted by a plurality of leaf springs. A plurality of leaf springs can be configured together with a sheet metal mold for producing slits in the rotating plate. And it can make it easy to bend in a rotation direction by twisting the both ends of a leaf | plate spring part 90 degree | times. In addition, since the slit portion and the elastic portion are integrally formed, it is possible to prevent an increase in cost due to an increase in the number of parts and to reduce the number of man-hours for assembling the elastic body. Further, since it is more resistant to axial translational vibration than a spiral spring, it can operate without contact between the slit of the rotating plate and the detector. In addition, since the elastic body can be made of the same material as the rotating plate, it is less susceptible to environmental temperature than resin and rubber, and can be used for a long time.

According to a sixth aspect of the present invention, the elastic body is a synthetic resin formed in a beam shape.
The elastic body of the present invention is formed by molding the rotating plate and the elastic body with resin. As a result, since the slit portion and the elastic body are formed in an integral structure, it is possible to prevent an increase in cost due to an increase in the number of parts and to increase the number of assembly steps for the elastic portion. As a method of forming the elastic body, there may be provided a plurality of thin beams, or a method using a beam curved so as to change the value of elasticity. Since the resin is lighter and less rigid than a metal, the diameter can be reduced without lengthening the elastic portion in the radial direction. In addition, the thickness of the outer peripheral portion can be easily adjusted, whereby the cutoff frequency can be easily changed.
According to a seventh aspect of the present invention, a member for increasing the inertia of the rotating plate is incorporated on the outer periphery of the rotating plate.
The present invention incorporates a member for increasing the inertia on the outer periphery of the rotating plate. This is because the inertia effect of increasing the inertia of the rotating plate can reduce the influence of higher-order rotational vibration that becomes a detection error, and can faithfully determine the speed fluctuation of an arbitrary target cycle. As a specific method, a member having high density (such as brass or iron) is formed in a ring shape, and is caulked and joined to the rotating plate.
An eighth aspect is characterized in that the outer peripheral edge of the rotating plate is bent.
The present invention increases the inertia of the detection unit by manufacturing a rotating plate of a material that can be bent and bending the outer peripheral side thereof. As a result, the inertia effect that increases the inertia of the detection unit can reduce the influence of higher-order rotational vibration that becomes a detection error, and can faithfully determine the speed fluctuation of any target cycle. Also, the radius of rotation can be reduced by bending, which is suitable for downsizing.

According to a ninth aspect of the present invention, a contact friction load is applied to the rotating plate.
According to the present invention, a contact friction load is applied to the rotating plate. This contact friction serves to reduce the influence of rotational vibration having a period (higher order) faster than an arbitrary period to be obtained. Thereby, highly accurate detection becomes possible.
A tenth aspect of the present invention is characterized in that the detector is mounted on the same frame as a bearing that supports the driven shaft.
In the present invention, the detector is attached to the same frame as the bearing supporting the driven shaft. Even if the vibration in the translation direction in the device or other translational vibration from the outside is applied, the detected part and the detector are mounted on the same base (frame). Vibrates with similar phase and amplitude. As a result, it is possible to reduce the influence of translational vibration that becomes a detection error.
An eleventh aspect is characterized in that an image forming apparatus includes the rotating body driving device according to any one of the first to tenth aspects.
According to the present invention, by providing the image forming apparatus with the rotating body driving device according to any one of claims 1 to 10, it is possible to improve image quality by suppressing jitter caused by rotational vibration.

According to the first aspect of the present invention, the rotation speed detecting means includes a rotating plate provided with at least one detected portion and a detector for detecting the detected portion, and the rotating plate is a driven shaft. Since it is fastened to the driven shaft via an elastic body that can be displaced in the rotational direction, even if higher-order vibration is superimposed on the driven shaft for various reasons, this elastic body blocks the vibration and causes the detected part to Therefore, the primary component can be detected with high accuracy. As a result, it is possible to improve the rotation accuracy by reducing the influence of fluctuations other than an arbitrary period and increasing the detection accuracy.
According to the second aspect of the present invention, since the hardness of the elastic body has a hardness that transmits the frequency of the primary component or less and blocks the frequency of the secondary component or more, the unnecessary frequency is detected by detecting the necessary frequency. Numbers can be removed.
Further, in claim 3, by making the elastic body a spiral spring, the detected part (slit) and the elastic body can be integrally formed, and the vibration in the axial direction in addition to the rotation direction can be blocked by the elastic body, Speed fluctuation of an arbitrary period from which higher-order vibrations are removed is transmitted to the detected part. As a result, it is possible to realize a rotating body driving device having a configuration that improves detection accuracy, has excellent heat resistance, and can be used for a long period of time.
According to a fourth aspect of the present invention, the elastic body is made of rubber so that it can be assembled by utilizing the expansion and contraction of the rubber, and higher-order vibrations are efficiently absorbed by the viscosity of the rubber. As a result, it is possible to realize a rotating body drive device having a configuration that improves detection accuracy and is excellent in assembling and suitable for weight reduction.
Further, in the fifth aspect, by making the elastic body a plurality of leaf springs, the detected portion (slit) and the elastic body can be integrally formed, and the rotational vibration can be blocked by the elastic body in the rotation direction. The speed fluctuation of an arbitrary period from which the next vibration is removed is transmitted to the detected part. As a result, it is possible to realize a rotating body driving device having a configuration that improves detection accuracy, has excellent heat resistance, and can be used for a long period of time.
Moreover, in Claim 6, by making the elastic body into a beam-like synthetic resin, the detected portion (slit) and the elastic body can be integrally molded, and the rotational vibration can be blocked by the elastic body in the rotation direction, Speed fluctuation of an arbitrary period from which higher-order vibrations are removed is transmitted to the detected part. In addition, since the rigidity is smaller than that of metal, it can be reduced in the radial direction. As a result, it is possible to improve the detection accuracy and to realize a rotating body drive device that is excellent in size and weight reduction.

According to the seventh aspect of the present invention, since a member for increasing the inertia is incorporated on the outer periphery of the rotating plate, the inertia moment of the entire rotating plate is increased, and there is a function of reducing the influence of higher-order rotational vibration that becomes a detection error. As a result, it is possible to realize a rotating body drive device that can efficiently detect a change in speed with an arbitrary period.
According to the eighth aspect of the invention, since the outer peripheral side of the rotating plate is bent, the inertia moment of the entire rotating plate is increased as compared with that of the same diameter, thereby reducing the influence of higher-order rotational vibration that becomes a detection error. There is work. As a result, it is possible to realize a rotating body drive device that can efficiently detect a change in speed with an arbitrary period.
Further, in the ninth aspect, since a contact-type friction load is applied to the rotating plate, there is a function of reducing the influence of rotational vibration having a cycle (higher order) faster than an arbitrary cycle to be obtained. As a result, it is possible to realize a rotating body drive device that can reduce vibrations that are detection errors.
Further, in claim 10, since the detector is mounted on the same frame as the bearing supporting the driven shaft, the detected portion and the detecting portion have the same amplitude and phase when there is a vibration in the translational direction from the outside. Translational vibration. As a result, it is possible to realize a rotating body drive device that can reduce translational vibration that is a detection error.
In the eleventh aspect, since the image forming apparatus includes the rotating body driving device according to any one of the first to tenth aspects, it is possible to improve image quality by suppressing jitter caused by rotational vibration.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the components, types, combinations, shapes, relative arrangements, and the like described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention only unless otherwise specified. .
Fig.1 (a) is a schematic block diagram of the rotary body drive device of this invention. The rotary body drive device 100 includes a drive motor (drive source) 1 whose rotational speed is controlled by the control device 10 and a drive gear (transmission mechanism section) connected to a drive shaft 16 of the drive motor 1 by a coupling 2. ) 3, a driven gear (transmission mechanism) 4 driven by the drive gear 3, a driven rotary body 6 coupled to the driven shaft 8 of the driven gear 4 by a coupling 5, and the driven shaft 8. The rotation plate (rotation speed detection means) 7, the detected part (rotation speed detection means) 9 mounted on the outer periphery of the rotation plate 7, and the detector (rotation speed detection means) for detecting the detected part 9 ) 15 and a control device (control unit) 10 that controls the rotational speed of the drive motor 1 based on the rotational speed detected by the detector 15. The rotating plate 7, the detected part 9 and the detector 15 constitute a rotational speed detecting means 17. The drive gear 16 and the driven side rotating body 6 are connected to the drive motor 1 and the driven gear 4 by the coupling 2 and the coupling 5, respectively, but may be directly attached to the drive shaft 16 and the driven shaft 8. Further, it is assumed that the detected portions 9 are attached to the outer periphery of the rotating plate 7 at equal intervals. The detected portion 9 may be a slit, a mark, or a magnet, and is determined according to the type of the detector 15. In the present embodiment, the detected portion 9 is a slit, and the detector 15 is a transmissive sensor.
FIG.1 (b) is a figure which shows the structure of the rotational speed detection means 17 which concerns on 1st Embodiment, (ba) is a front view, (bb) is a sectional side view. The same components will be described with the same reference numerals. The rotation speed detecting means 17 includes four slits 9 arranged at equal intervals on the outer periphery of the rotating plate 7, a transmission type sensor 15 that transmits light through the four slits 9 and detects the position, and the rotating plate 7. The rotating plate 7 is fastened to the driven shaft 8 via the elastic body 20 that can be displaced in the rotational direction of the driven shaft 8.
As described above, the present embodiment is a configuration for measuring the passage time of the slit 9 instead of counting the number of slits 9 and determining the speed fluctuation of an arbitrary period from the result with high accuracy. As shown in FIG. 1 (a), the drive gear 1 is rotated by the drive motor 1 via the coupling 2 or the like (no coupling is required when the gear shaft is configured with a gear tooth), and the driven gear 4 and the coupling 5 are rotated. The driven-side rotator 6 is driven via Normally, constant speed control is performed by the control device 10 based on the output from the motor angle detection signal 13 on the drive shaft 16. In the configuration of the present embodiment, the slit 9 is provided on the outer periphery of the rotating plate 7, the passage time is measured by the transmission sensor 15, the speed fluctuation of an arbitrary period is calculated from this time, and the speed reference is made to cancel this. The signal 12 is generated and operated by the control device 10. In order to measure this time, in particular, when higher-order rotational vibration is applied to the slit 9 except for an arbitrary period, the speed fluctuation detection accuracy of the arbitrary period is lowered due to the influence. Therefore, as shown in FIG. 1B, the rotating plate 7 and the driven shaft 8 are fastened via an elastic body 20 that can be displaced in the rotational direction. As a result, even if higher-order vibration is superimposed on the driven shaft 8 for various reasons, the vibration is blocked by the elastic body 20 and is not transmitted to the slit 9.
Further, the hardness of the elastic body 20 is set so as to transmit the vibrations having an arbitrary period or less. In general, vibrations in rotation are large in the primary component (driven shaft 1 rotation period = frequency fo [Hz]) in eccentric assembly or the like. If this is an arbitrary period, the secondary component (frequency 2 × fo) [Hz]) By blocking the above components, the primary component can be detected with high accuracy. Thereby, if correction control is performed using this detection result, highly accurate rotation drive can be performed.

  2A and 2B are diagrams showing the configuration of the rotational speed detecting means 17 according to the second embodiment of the present invention, wherein FIG. 2A is a front view and FIG. 2B is a side sectional view. The same components will be described with the same reference numerals. The rotation speed detecting means 17 includes four slits 9 arranged at equal intervals on the outer periphery of the rotating plate 7, a transmission type sensor 15 that transmits light through the four slits 9 and detects the position, and the rotating plate 7. The rotating plate 7 is fastened to the driven shaft 8 via the elastic body 21 that can be displaced in the rotation direction of the driven shaft 8. The elastic body 21 of this embodiment is comprised by the spiral spring 21a like FIG. Thus, the spiral spring 21a can be configured together with the sheet metal mold for manufacturing the slit 9. Further, since the slit 9 and the spiral spring 21a are integrally formed, it is possible to prevent an increase in cost due to an increase in the number of parts and to increase the number of steps for assembling the spiral spring 21a. In addition, since the translational vibration other than the rotation direction can be elastically deformed, higher-order translational vibration in the axial direction can also be blocked. In this method, the spiral spring 21a can be made of the same material as that of the rotating body 7, so that it is less susceptible to environmental temperature than resin or rubber, and can be used for a long time.

FIGS. 3A and 3B are diagrams showing the configuration of the rotational speed detecting means 17 according to the third embodiment of the present invention, where FIG. 3A is a front view and FIG. 3B is a side sectional view. The same components will be described with the same reference numerals. The rotation speed detecting means 17 includes four slits 9 arranged at equal intervals on the outer periphery of the rotating plate 7, a transmission type sensor 15 that transmits light through the four slits 9 and detects the position, and the rotating plate 7. The rotating plate 7 is fastened to the driven shaft 8 via an elastic body 22 that can be displaced in the rotational direction of the driven shaft 8. The elastic body of this embodiment is comprised with rubber | gum 22a like FIG. By interposing the rubber 22a between the slit 9 and the driven shaft 8, the assembling work can be simplified using the expansion and contraction of the rubber 22a. In addition, the rubber 22a has a higher viscosity than metal and can absorb high-order rotation and translational vibration efficiently, so that the shape of the rubber 22a can be reduced, and it is suitable for a more compact layout and can be reduced in weight.
4A and 4B are diagrams showing the configuration of the rotational speed detecting means 17 according to the fourth embodiment of the present invention, wherein FIG. 4A is a front view, and FIG. 4B is a side sectional view. The same components will be described with the same reference numerals. The rotation speed detecting means 17 includes four slits 9 arranged at equal intervals on the outer periphery of the rotating plate 7, a transmission type sensor 15 that transmits light through the four slits 9 and detects the position, and the rotating plate 7. The rotary plate 7 is fastened to the driven shaft 8 via the elastic body 23 that can be displaced in the rotation direction of the driven shaft 8. The elastic body of this embodiment is comprised by the some leaf | plate spring 23a like FIG. A plurality of leaf springs can be configured together with the sheet metal mold for manufacturing the slit 9. By twisting both ends of the leaf spring 23a by 90 degrees as shown in the figure, it is possible to easily bend in the rotation direction. Since the slit 9 and the elastic body 23 are formed in an integral structure, it is possible to prevent an increase in cost due to an increase in the number of parts and to increase the number of assembling steps for the elastic body 23. Further, since it is more resistant to translational vibration in the axial direction than the spiral spring 21a, it can operate without contact between the slit 9 of the detected portion and the detector 15. Further, since the elastic body 23 can be made of the same material as that of the rotating plate 7, it is less susceptible to environmental temperature than resin and rubber, and can be used for a long time.

FIG. 5 is a diagram showing the configuration of the rotational speed detecting means 17 according to the fifth embodiment of the present invention. The same components will be described with the same reference numerals. The rotation speed detecting means 17 includes four slits 9 arranged at equal intervals on the outer periphery of the rotating plate 7, a transmission type sensor 15 that transmits light through the four slits 9 and detects the position, and the rotating plate 7. The rotating plate 7 is fastened to the driven shaft 8 via an elastic body 24 that can be displaced in the rotational direction of the driven shaft 8. As shown in FIG. 5, the rotating body 7 and the elastic body 24 of the elastic body of this embodiment are molded with resin. Since the slit 9 and the elastic body 24 are integrally formed, it is possible to prevent an increase in cost due to an increase in the number of parts and to increase the number of assembling steps for the elastic body 24. As a method of forming the elastic body 24, there may be provided a plurality of thin beams 24a as shown in the figure, or a method using a beam 24b curved so as to change the value of elasticity. Since it is lighter and less rigid than metal, the diameter of the elastic body 24 can be reduced without lengthening it in the radial direction. In addition, the thickness of the outer peripheral portion can be easily adjusted, whereby the cutoff frequency can be easily changed.
FIG. 6 is a diagram showing the configuration of the rotational speed detecting means 17 according to the sixth embodiment of the present invention. The same components will be described with the same reference numerals. The rotation speed detecting means 17 includes four slits 9 arranged at equal intervals on the outer periphery of the rotating plate 7, a transmission type sensor 15 that transmits light through the four slits 9 and detects the position, and the rotating plate 7. The rotating plate 7 is fastened to the driven shaft 8 via the elastic body 20 that can be displaced in the rotational direction of the driven shaft 8. And in this embodiment, the member 25 which increases an inertia is integrated on the outer periphery of the rotating plate 7 like FIG. This is an inertia effect that increases the inertia of the rotating plate 7, can reduce the influence of higher-order rotational vibration that becomes a detection error, and can faithfully obtain the speed fluctuation of an arbitrary period of interest. As a specific method, a member having a high density (such as brass or iron) is formed in a ring shape, and the detection unit is caulked and coupled.

FIG. 7 is a diagram showing the configuration of the rotational speed detecting means 17 according to the seventh embodiment of the present invention. The same components will be described with the same reference numerals. The rotation speed detecting means 17 includes four slits 9 arranged at equal intervals on the outer periphery of the rotating plate 7, a transmission type sensor 15 that transmits light through the four slits 9 and detects the position, and the rotating plate 7. The rotating plate 7 is fastened to the driven shaft 8 via the elastic body 20 that can be displaced in the rotational direction of the driven shaft 8. In the present embodiment, as shown in FIG. 7, the rotating plate 7 is made of a material that can be bent and the outer peripheral side thereof is bent inward, for example, to increase the inertia of the rotating plate 7. This is an inertia effect that increases the inertia of the rotating plate 7, can reduce the influence of higher-order rotational vibration that becomes a detection error, and can faithfully obtain the speed fluctuation of an arbitrary period of interest. In addition, the bending radius can be reduced by bending, which is suitable for downsizing.
FIG. 8 is a diagram showing the configuration of the rotational speed detecting means 17 according to the eighth embodiment of the present invention. The same components will be described with the same reference numerals. The rotation speed detecting means 17 includes four slits 9 arranged at equal intervals on the outer periphery of the rotating plate 7, a transmission type sensor 15 that transmits light through the four slits 9 and detects the position, and the rotating plate 7. The rotating plate 7 is fastened to the driven shaft 8 via the elastic body 20 that can be displaced in the rotational direction of the driven shaft 8. In this embodiment, as shown in FIG. 8, the friction damping part 27 is brought into contact with the rotating plate 7 so that a contact-type friction load is applied. The friction damping part 27 is composed of an arm 27a and a sliding part 27b provided at the tip thereof, and has a function of reducing the influence of rotational vibration having a period (higher order) faster than an arbitrary period desired to be obtained by contact friction. Thereby, highly accurate detection becomes possible.

  FIG. 9 is a diagram showing the configuration of the rotational speed detecting means 17 according to the ninth embodiment of the present invention. The same components will be described with the same reference numerals. The rotation speed detecting means 17 includes four slits 9 arranged at equal intervals on the outer periphery of the rotating plate 7, a transmission type sensor 15 that transmits light through the four slits 9 and detects the position, and the rotating plate 7. The rotating plate 7 is fastened to the driven shaft 8 via the elastic body 20 that can be displaced in the rotational direction of the driven shaft 8. In this embodiment, the transmission sensor 15 is attached to the same frame 29 as the bearing 28 that supports the driven shaft 8 as shown in FIG. As a result, even if translational vibrations in the device or other translational vibrations from the outside are applied, the parts to be detected and the parts to be detected are assembled on the same base (frame). The sensor 15 vibrates with the same phase and amplitude. As a result, it is possible to reduce the influence of translational vibration that becomes a detection error.

  FIG. 10 is a diagram schematically showing the internal structure of an image forming apparatus using the rotating body driving device of the present invention. A paper feed cassette 30 is detachably mounted on the right side of the image forming apparatus main body 200, and a paper discharge port 31 is provided on the left side of the main body. A photosensitive member 33 is rotatably provided above a paper conveyance path 32 from the paper feed cassette 30 to the paper discharge port 31, and a charger 34, an exposure device 35, and a development device as process units are provided around the photoconductor 33. 36 are arranged. Further, a transfer device 37, a cleaning device 38, a static eliminator 39, and the like are arranged on the outer periphery of the photosensitive member 33. Further, a paper feed roller 40, a registration roller 41, a fixing device 42 having a heat roller 42a and a press roller 42b, and a paper discharge roller 43 are arranged from upstream to downstream along the paper transport path 32. With such a configuration, the surface of the photosensitive member is charged by the charger 34, and an electrostatic latent image is formed by scanning the laser beam from the exposure device 35 in that portion. Thereafter, the electrostatic image is developed as a toner image by the developing device 36 by the rotation of the photosensitive member 33. On the other hand, the paper in the paper feed cassette 30 is pulled out to the registration roller 41 by the paper feed roller 40, and the paper is fed to the lower part of the photoconductor 33 by the registration roller 41 that rotates in synchronization with the rotational movement of the photoconductor 33. The toner image on the photosensitive member 33 is transferred to a sheet by the transfer unit 37, and the transferred image on the sheet is fixed when the sheet passes through the fixing unit 42. Thereafter, the sheet after fixing is discharged from the paper discharge port 31 by the paper discharge roller 43. In the case of a color machine, although not shown, this process unit is mounted for four colors.

In such a product, the constant speed characteristic of the photosensitive drum shaft directly affects the image quality. When the motor torque is transmitted to the shaft of the photosensitive member 33 by a gear and driven, the torque fluctuation of the motor itself is suppressed. Of course, the effect of transmission error in a transmission mechanism such as a gear is detected on the drum shaft, and the motor is driven so as to cancel it, so that the constant speed can be maintained.
Therefore, the detected part passing time is measured by the detected part when detecting the speed of the driven shaft that drives the photosensitive member 33 and the base side (frame side) detector, and the speed fluctuation of an arbitrary period is calculated therefrom. In the image forming apparatus that performs correction control based on this, the driven shaft and the detected part are fastened via an elastic body that can be displaced in the rotational direction. In an image forming apparatus, a plurality of units use gears to form an image, and various vibrations are generated. These vibrations are less likely to be transmitted to the detected part through the elastic body, and the speed fluctuation of an arbitrary period can be measured faithfully.
Especially in a color machine, since multiple colors are superimposed, the speed fluctuation of this arbitrary period (for example, the period of the primary component of the driven shaft generated by gear eccentricity, etc.) is accurately measured, and correction control is performed between each color. The occurrence of uneven color can be suppressed. Up to this point, the case where the present invention is applied to the photosensitive member 33 has been described. Similarly, the present invention can also be applied to a drive control unit for a driving roller that drives a photosensitive belt and a drive control unit for a drive roller in an intermediate transfer belt system. Needless to say.

The schematic block diagram of the rotary body drive device of this invention. The figure which shows the structure of the rotational speed detection means 17 which concerns on the 2nd Embodiment of this invention. The figure which shows the structure of the rotational speed detection means 17 which concerns on the 3rd Embodiment of this invention. The figure which shows the structure of the rotational speed detection means 17 which concerns on the 4th Embodiment of this invention. The figure which shows the structure of the rotational speed detection means 17 which concerns on the 5th Embodiment of this invention. The figure which shows the structure of the rotational speed detection means 17 which concerns on the 6th Embodiment of this invention. The figure which shows the structure of the rotational speed detection means 17 which concerns on the 7th Embodiment of this invention. The figure which shows the structure of the rotational speed detection means 17 which concerns on the 8th Embodiment of this invention. The figure which shows the structure of the rotational speed detection means 17 which concerns on the 9th Embodiment of this invention. 1 is a diagram schematically showing an internal structure of an image forming apparatus using a rotating body driving device of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Drive motor (drive source), 2 coupling, 3 drive gear (transmission mechanism part), 4 driven gear (transmission mechanism part), 5 coupling, 6 driven side rotary body, 7 rotary plate (rotation speed detection means), 8 Driven shaft, 9 Detected part (rotational speed detecting means), 10 Control device (control part), 15 Detector (rotational speed detecting means), 16 Drive shaft, 100 Rotating body drive device

Claims (11)

Detecting the rotational speed of the drive source that can control the rotational speed from the outside, the transmission mechanism that transmits the rotational torque of the drive source, and the driven shaft that is driven by the rotational torque transmitted by the transmission mechanism A rotating body drive device comprising: a rotation speed detection unit; and a control unit that controls the rotation speed of the drive source based on the rotation speed detected by the rotation speed detection unit,
The rotation speed detecting means includes a rotating plate provided with at least one detected portion and a detector for detecting the detected portion, and the rotating plate is displaceable in the rotation direction of the driven shaft. A rotating body driving device, wherein the rotating body driving device is fastened to the driven shaft via an elastic body.   2. The rotating body drive device according to claim 1, wherein the elastic body is configured by a member having a hardness that transmits a frequency equal to or lower than a first-order component and blocks a frequency equal to or higher than a second-order component.   The rotating body driving device according to claim 1, wherein the elastic body is a spiral spring.   The rotating body driving device according to claim 1, wherein the elastic body is rubber.   The rotating body drive device according to claim 1, wherein the elastic body is a plurality of leaf springs.   3. The rotating body driving device according to claim 1, wherein the elastic body is a synthetic resin formed in a beam shape.   The rotating body drive device according to claim 1, wherein a member that increases inertia of the rotating plate is incorporated on an outer periphery of the rotating plate.   The rotating body driving device according to claim 1, wherein an outer peripheral edge portion of the rotating plate is bent.   The rotating body driving device according to claim 1, wherein a contact friction load is applied to the rotating plate.   The rotating body driving device according to any one of claims 1 to 9, wherein the detector is mounted on the same frame as a bearing that supports the driven shaft.   An image forming apparatus comprising the rotating body driving device according to claim 1.

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