JP4385673B2 - Rotation drive control device in image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer for driving and controlling a rotating body such as a photosensitive drum, an intermediate transfer belt, a recording sheet conveying roller, a developing device, and a fixing device at a predetermined rotational speed. More specifically, the present invention relates to an improvement of a rotary drive control device of a type in which a motor as a drive source and these rotated bodies are connected via a friction transmission type traction roller instead of a reduction gear. .

JP 2002-171721 A

  For example, in an image forming apparatus such as an electrophotographic copying machine or a laser beam printer, during a process of forming a toner image according to image information and transferring and fixing the toner image on a recording sheet, a photosensitive drum, a developer conveying roll, There are various rotating bodies such as a transfer roll, a drum cleaner, a recording sheet conveying roll, and a fixing roll, and these are rotated at a predetermined speed by a plurality of motors. In order to give a predetermined rotational speed to each rotating body, the output shafts of these motors are connected to the rotating body such as a photosensitive drum via a speed reduction mechanism such as a speed reduction gear train. In particular, full-color copying machines and full-color laser beam printers are required to superimpose yellow, cyan, magenta, and black color toner images with high precision, and the rotational speed of the photosensitive drum and intermediate transfer body is highly accurate. There is a need to control.

  However, when the motor rotation speed is reduced using a reduction gear train, due to gear formation accuracy, eccentricity with respect to the rotation shaft, etc., vibrations with a frequency corresponding to the rotation speed are generated in meshing between the gears. Easy to do. For this reason, when the rotational speed of the motor is transmitted to the photosensitive drum, intermediate transfer body, etc. via the reduction gear, even if the rotational speed of the motor is controlled with high accuracy, the rotational speed unevenness is not detected on the photosensitive drum, etc. There is a concern that color deviation and color unevenness cannot be completely prevented in a strict sense.

  Therefore, in recent years, a traction type planetary reduction device has been proposed as a device that reduces the rotation of a motor without using a gear (Japanese Patent Laid-Open No. 2002-171721). In this planetary reduction device of the traction type, an internal ring is arranged so as to surround the sun roller connected to the output shaft of the motor, and between the inner peripheral surface of the internal ring and the outer peripheral surface of the sun roller. A plurality of planetary rollers are sandwiched between them, and an output shaft that is disposed on the same axis as the sun roller and rotates by the revolution of the planetary rollers is provided. With such a configuration, when the sun roller rotates with the rotation of the motor, the planetary roller rotates due to the frictional force acting between the sun roller and the planetary roller, and the planetary roller rotates while the sun roller rotates. Revolve around. The revolution causes the output shaft to rotate, and the rotation of the motor is transmitted to the output shaft in a decelerated state.

  In such a reduction device using a traction method, there is no meshing vibration of teeth like a gear, and therefore it is possible to transmit the rotation of the motor to a rotating body such as a photosensitive drum with high accuracy. On the other hand, when the sun roller, the planetary roller, and the internal ring are worn due to use over time, there is a problem that slippage occurs gradually between these rollers. This slip gradually becomes more noticeable as the usage time accumulates. Finally, no matter how fast the motor is rotated, a predetermined rotational speed cannot be given to the rotating body such as the photosensitive drum, and the recorded image In addition, there is a problem that image quality deterioration such as a formation position shift, color shift, and color unevenness occurs. In addition, there is a problem that abnormal noise and noise are generated from the reduction gear due to wear.

  Further, since the planetary roller is revolved based on the frictional force generated between the sun roller and the planetary roller, an excessive load is applied to the output shaft even if the solar roller or planetary roller is not worn. In this case, for example, when there is an abnormality in the cleaning blade of the photosensitive drum and an overload acts on the rotation of the photosensitive drum, slip occurs between the planetary roller and the sun roller. Again, the rotation of the output shaft cannot be controlled to a predetermined rotation speed, and it becomes difficult to form a high-quality recorded image.

  The present invention has been made in view of such problems, and an object of the present invention is to provide an image forming apparatus that transmits the rotation of a motor to a rotating body such as a photosensitive drum using a traction type reduction device. To provide a drive control device capable of promptly issuing a warning to a user and taking necessary measures in such a user when it is determined that the image quality of a recorded image is deteriorated due to slippage in the speed reducer It is in.

  That is, the present invention is a rotation drive control device for controlling the rotation speed of a rotating body included in an image forming apparatus, and includes a motor that rotates at a speed according to a control signal and a plurality of rollers that are in pressure contact with each other. A reduction roller mechanism that transmits the rotation of the motor to the rotated body through these rollers while reducing the rotation of the motor, a rotation speed of the output shaft of the reduction roller mechanism, and a target rotation speed to be given to the rotated body. And a rotation control unit that sends a control signal to the motor so that the rotation speeds of the two coincide with each other. The rotation control unit further includes the rotation speed of the output shaft of the speed reduction roller mechanism and the motor. The amount of slippage of the speed reduction roller mechanism is detected by comparing with the rotation speed of the output shaft, and when the amount of slippage exceeds a predetermined value, a warning signal is sent to the control unit of the image forming apparatus. And it is characterized in Rukoto.

  In this rotation drive control device, the rotation of the motor is transmitted to the rotated body via the speed reduction roller mechanism, and the rotation control unit detects the rotational speed of the output shaft of the speed reduction roller mechanism, and the detected speed is detected. The rotation of the motor is controlled so that the detected speed and the target rotational speed coincide with each other compared with the target rotational speed to be given to the rotating body. At this time, if there is slip between the rollers that constitute the speed reduction roller mechanism and transmit the rotation of the motor, the rotational speed of the output shaft of the motor is further increased. By comparing the rotational speed of the output shaft of the roller mechanism with the rotational speed of the output shaft of the motor, the slip amount of each roller of the speed reduction roller mechanism can be grasped. If this slippage becomes too significant, it becomes impossible to rotate the rotated body in the image forming apparatus such as the photosensitive drum or the intermediate body at a predetermined speed no matter how much the rotation of the motor is increased. There is an increased possibility of forming position deviation, color deviation, and color unevenness. Accordingly, when the grasped slip amount exceeds a predetermined value, the rotation control unit sends a warning signal to the control unit of the image forming apparatus. As a result, the user can be notified of abnormalities in the speed reduction roller mechanism through the user interface such as the liquid crystal operation panel of the image forming apparatus, and the life of the speed reduction roller mechanism can be detected before image quality deterioration, noise, or noise occurs. In addition, maintenance such as replacement can be performed.

  Here, the cause of the remarkable slip between the rollers constituting the speed reduction roller mechanism is that the wear of the roller itself has progressed due to the use over time, and from the rotated body to the speed reduction roller mechanism. It can be considered that an excessive load is acting, and as a result, slip occurs between the rollers.

  In the former case, since the slip generated between the rollers tends to gradually increase, the rotation of the output shaft of the speed reduction roller mechanism can be achieved by increasing the rotational speed of the motor even if such slip occurs. The speed can be matched to the target rotational speed. On the other hand, in the latter case, the rotation of the output shaft of the speed reduction roller mechanism itself is suppressed by an overload, and even if the rotation speed of the motor is increased, the rotation speed of the output shaft of the speed reduction roller mechanism becomes the target rotation speed. It is impossible to match. Therefore, when the slip amount of the speed reduction roller mechanism exceeds a predetermined value, it is checked whether or not the rotational speed of the output shaft of the speed reduction roller mechanism matches the target rotation speed, and the two match. If this is the case, it can be determined that the slippage amount has increased due to wear of the speed reduction roller mechanism, so that the rotation signal of the motor, that is, the recording image forming operation continues, and a warning signal is sent to notify the malfunction of the speed reduction roller mechanism. What is necessary is just to send with respect to the control part of a forming apparatus. As a result, the user can quickly arrange replacement of the speed reduction roller mechanism and the like, and can continuously perform copy jobs and print jobs.

  On the other hand, it is checked whether or not the rotational speed of the output shaft of the speed reduction roller mechanism matches the target rotational speed, and if both do not match for a predetermined time or more, that is, the rotational speed of the motor to match both speeds. If the two speeds still do not match, it can be determined that an excessive load is acting on the output shaft of the speed reduction roller mechanism from the rotated body. As described above, even if the rotation of the rotating body is continued, there is a high probability that the recorded image formation position shift, color shift, and color unevenness will occur. The operation is stopped and a warning signal is sent to the control unit of the image forming apparatus to notify the overload of the rotated body. As a result, it is possible to stop the rotation of the motor before an excessive current flows to the motor and take appropriate measures.

  According to the rotational drive control device in the image forming apparatus of the present invention configured as described above, the rotation control unit grasps the slip amount of each roller of the speed reduction roller mechanism and when the grasped slip amount exceeds a predetermined value. Is configured to send a warning signal to the control unit of the image forming apparatus, so that a warning is promptly given to the user when it is determined that the image quality of the recorded image is deteriorated due to slippage in the speed reducer. It is possible to take necessary measures in such a user.

Hereinafter, a rotational drive control device in an image forming apparatus of the present invention will be described in detail with reference to the accompanying drawings.
First, FIG. 1 shows an example of a color laser beam printer to which the rotary drive device of the present invention can be applied. The laser beam printer includes four image forming engines 10Y, 10M, 10C, and 10Bk that form toner images for each of yellow, magenta, cyan, and black, and the toner images are primarily transferred from the image forming engines. An intermediate transfer belt 20 is provided, and the toner image multiple-transferred to the intermediate transfer belt 20 is secondarily transferred to the recording sheet P to form a full color image.

  The intermediate transfer belt 20 is formed in an endless shape and is wound around three belt transporting rolls 21 to 23 including a driving roll 21, and each color image forming engine 10Y, 10M, while rotating in the direction of the arrow. It is configured to receive a primary transfer of a toner image formed with 10C and 10Bk. Further, a secondary transfer roll 30 is disposed at a position facing the belt conveying roll 23 with the intermediate transfer belt 20 interposed therebetween, and the recording sheet P is interposed between the transfer roll 30 and the intermediate transfer belt 20 that are pressed against each other. The toner image is secondarily transferred from the intermediate transfer belt 20 by being inserted. That is, the belt conveyance roll 23 functions as a backup roll for the transfer roll 30, and the transfer roll 30 and the belt conveyance roll 23 constitute a secondary transfer unit.

  The intermediate transfer belt 20 is stretched between three belt conveyance rolls 21 to 23, and a substantially horizontal image receiving span is formed between the belt conveyance rolls 21 and 22, while the two are directly below the image receiving span. A third belt conveyance roll 23 facing the next transfer roll 30 is disposed and stretched in an inverted triangular shape as a whole.

  The four image forming engines 10Y, 10M, 10C, and 10Bk described above are arranged in parallel on the image receiving span of the intermediate transfer belt 20, and a toner image formed according to image information of each color is intermediate transferred. Primary transfer is performed on the belt 20. These four image forming engines are arranged in the order of yellow 10Y, magenta 10M, cyan 10C, and black 10Bk along the rotation direction of the intermediate transfer belt 20, and the black image forming that is most frequently used is arranged. The image engine 10Bk is disposed closest to the secondary transfer portion. Each of the image forming engines 10Y, 10M, 10C, and 10Bk includes a raster scanning unit 12 that exposes the photosensitive drum 11 provided in each image forming engine in accordance with the image information. The laser beam Bm modulated accordingly exposes the photosensitive drums 11 of the image forming engines 10Y, 10M, 10C, and 10Bk.

  Each of the image forming engines 10Y, 10M, 10C, and 10Bk is sensitized by exposure of the photosensitive drum 11, the charger 13 that charges the photosensitive drum 11 to a uniform background portion potential, and the laser beam Bm. A developing device 14 that develops the electrostatic latent image formed on the photosensitive drum 11 to form a toner image, and residual toner and paper dust from the surface of the photosensitive drum 11 after the toner image is transferred to the intermediate transfer belt 20. A drum cleaner 15 that removes toner and a pre-cleaning static eliminator 16 that neutralizes residual toner prior to cleaning by the drum cleaner, and forms a toner image corresponding to image information of each color on the photosensitive drum 11. Configured to get.

  Primary transfer rolls 17Y, 17M, 17C, and 17Bk are disposed at positions facing the photosensitive drums 11 of the image forming engines 10Y, 10M, 10C, and 10Bk so as to sandwich the intermediate transfer belt 20, and these transfer rolls. By applying a predetermined transfer bias voltage to 17Y, 17M, 17C, and 17Bk, an electric field is formed between the photoconductive drum 11 and the transfer rolls 17Y, 17M, 17C, and 17Bk. The charged toner image is transferred to the intermediate transfer belt 20 by Coulomb force.

  Therefore, in forming a full color image by the color laser beam printer, first, the raster scanning unit 12 applies the photosensitive drums 11 of the image forming engines 10Y, 10M, 10C, and 10Bk at a predetermined timing according to the image information of each color. By exposure, a toner image corresponding to the image information is formed on each of the image forming engines 10Y, 10M, 10C, and 10Bk. The toner images formed by the image forming engines 10Y, 10M, 10C, and 10Bk are sequentially transferred to the rotating intermediate transfer belt 20, and a multiple toner image in which the respective color toner images are overlapped on the intermediate transfer belt 20. It is formed.

  On the other hand, after the recording sheet P is pulled out from the sheet cassette 40 one by one by the sheet feeding roll 41, the intermediate transfer belt 20 and the secondary transfer roll 30 pass through a predetermined sheet feeding path 46 indicated by a broken line in the drawing. Is fed to the secondary transfer portion in contact. A registration roll 42 is provided on the front side of the secondary transfer portion, and the recording sheet P is primary-transferred onto the intermediate transfer belt 20 by controlling the entry timing with respect to the secondary transfer portion by the registration roll 42. Registration with the toner image is performed.

  The backup roll 23 facing the secondary transfer roll 30 with the intermediate transfer belt 20 interposed therebetween is formed by covering the surface of the insulating roll with a semiconductive sheet, and a predetermined transfer bias voltage is applied to the surface. The conductive contact roll 50 is in contact. Accordingly, when a transfer bias voltage having the same polarity as that of the toner image is applied to the contact roll 50 and a charge is applied to the surface of the backup roll 23, the transfer roll 30 and the intermediate transfer located on the back side of the recording sheet P are transferred. A transfer electric field is formed between the backup roll 23 located on the back side of the belt 20, and the toner image held on the intermediate transfer belt 20 is electrostatically transferred to the recording sheet P.

  The recording sheet P on which the toner image has been secondarily transferred is peeled off from the intermediate transfer belt 20 and then conveyed to the fixing device 44 by a series of two sheet conveying belts 43 arranged in series. The recording sheet P is fixed on the toner image by the fixing device 44 and then discharged to the paper discharge tray 45, whereby the formation of the full color image on the recording sheet P is completed. Further, in this printer, an inverter passage 47 for inverting the front and back of the recording sheet P between the fixing device 44 and the discharge tray 45 in order to enable so-called face-down discharge with the image surface of the recording sheet P facing downward. Is formed. Further, the inverter passage 47 is connected to the above-described sheet feeding passage 46 by a sheet re-transmission passage 48. By feeding the recording sheet P that is reversed upside down in the inverter passage 47 to the secondary transfer portion again, the recording sheet P It is possible to form recorded images on both the front and back sides.

  In this color printer, a motor for rotationally driving the photosensitive drum 11 is provided for each of the image forming engines 10Y, 10M, 10C, and 10Bk in order to perform the transfer position alignment of each color toner image on the intermediate transfer belt 20 with high accuracy. Thus, the rotational speed of each photosensitive drum 11 can be individually controlled. The rotation of each motor is input to the photosensitive drum via a traction type planetary reduction mechanism, and after the rotational speed of the output shaft of the motor is reduced by a predetermined reduction ratio, the photosensitive member is output from the output shaft of the planetary reduction mechanism. It is transmitted to the rotating shaft of the drum 11.

  FIG. 2 is a view showing an example of a traction type planetary reduction roller mechanism. The planetary speed reduction roller mechanism 50 includes a sun roller 51 that can directly use the output shaft of the motor M, a plurality of planetary rollers 52 arranged so as to be in contact with the outer peripheral surface of the sun roller 51, and the planetary rollers 52 outside. And an output ring 54 disposed on the same axial center as the sun roller 51, and fixed to the output shaft 54 and rotatable about the planetary roller 52. The output shaft 54 is supported on a housing 56 via a bearing, while the sun roller 51 is fixed to an end plate 57 via a bearing. Then, by fixing the end plate 57 to the housing 56, a housing space for the sun roller 51, the planetary roller 52, the internal ring 53, and the carrier 55 is formed in the housing 56, and the housing space is lubricated. Filled with grease as agent.

  Each planetary roller 52 has a large diameter portion 52a and a pair of small diameter portions 52b provided so as to sandwich the large diameter portion 52a from both sides in the axial direction. The former large diameter portion 52a has an outer peripheral surface thereof. Is in pressure contact with the outer peripheral surface of the sun roller 51. Each small diameter portion 52 b of the planetary roller 52 is formed in a tapered shape, and the outer peripheral surface of the small diameter portion 52 b is in pressure contact with the inner peripheral surface of the internal ring 53. These planetary rollers 52 are rotatably supported by a rod 58 standing on the carrier 55, and are rotated along with the rotation of the sun roller 51 with the rod 58 as a rotation center.

  On the other hand, the internal ring 53 is composed of a fixed ring 53a and a movable ring 53b, and the inner peripheral surface of each ring 53a, 53b is formed in a tapered shape that matches the outer peripheral surface of the small diameter portion of the planetary roller 52. . The movable ring 53 b and the fixed ring 53 a are arranged so as to sandwich the large diameter portion 52 a of the planetary roller 52 from the axial direction, and the fixed ring 53 a is fixed to the housing 56. The movable ring 53b is fixed to the housing 56 with respect to the circumferential direction thereof, but is disposed so as to be movable within the housing 56 with respect to the axial direction. Further, the movable ring 53b is pressed in the axial direction by a compression coil spring 59, and the movable ring 53b and the fixed ring 53a sandwich the small diameter portion 52b of the planetary roller 52 from both sides in the axial direction by the pressing force. The tapered inner peripheral surface and the tapered inner peripheral surface of the fixing ring 53a are configured to come into pressure contact with the tapered outer peripheral surface of the small diameter portion 52b of the planetary roller 52, respectively.

  The output shaft of the motor M is connected to the sun roller 51 of the planetary reduction roller mechanism 50 configured as described above, and the sun roller 51 is rotated. The output shaft of the motor M itself is inserted into the housing 56, and the sun The roller 51 can be used. When the output shaft of the motor M, that is, the sun roller 51 is rotated, the planetary roller 52 pressed against the outer peripheral surface of the sun roller 51 is rotated along with the rotation of the sun roller 51. Since the small diameter portion 52b is in pressure contact with the internal ring 52 (movable ring 52b and fixed ring 52a) fixed in the circumferential direction, the planetary roller 52 revolves around the sun roller 51 while rotating. As a result, the carrier 55 supporting the planetary roller 52 rotates, and the output shaft 54 to which the carrier 55 is fixed rotates at the revolution speed of the planetary roller 52.

  FIG. 3 is a block diagram showing a drive control device using such a traction type planetary speed reduction roller mechanism 50. A configuration surrounded by a broken line in the drawing is a drive control device for the photosensitive drum 11 and is provided for each photosensitive drum. That is, in the tandem type full-color image forming apparatus shown in FIG. 1, four drive control devices are provided, and each drive control device rotates the photosensitive drum 11 with the main control board 1 of the image forming device. It is designed to send and receive signals related to speed. The drive control device includes a rotation control unit 2 configured by a computer system, and the rotation control unit 2 sends a drive control signal to the drive motor M of the photosensitive drum 11.

  A traction type (friction transmission type) planetary reduction device has characteristics such as less fluctuation in angular velocity, lower noise, and lower vibration than a reduction device using a gear. Above all, since gear meshing vibration does not occur, there is an advantage that striped image quality defects called banding are unlikely to occur in a recorded image. On the other hand, the rotational torque is not transmitted by the meshing of the gears, but the rotational torque is transmitted by the frictional force between the rollers that are in pressure contact with each other. There is a characteristic that the rotation speed of the output shaft of the planetary reduction roller mechanism does not correspond one-to-one with the rotation speed of the drive motor.

  Therefore, the planetary roller speed reduction mechanism 50 is provided with an output side encoder 60 for detecting the rotation speed of the output shaft 54, and the rotation control unit 2 receives the detection signal of the output side encoder 60. By reading, the rotational speed of the output shaft 54 of the planetary reduction roller mechanism 50, that is, the rotational speed of the photosensitive drum 11 is grasped. The rotation control unit 2 compares the rotation speed of the output shaft 54 of the planetary reduction roller mechanism 50 with the target rotation speed of the photosensitive drum 11 instructed from the main control board 1 of the image forming apparatus. The rotation of the drive motor M is feedback controlled so that the rotation speed matches the target rotation speed. Thereby, it is possible to control the rotation of the photosensitive drum 11 which is a rotated body at an optimum speed for each of the image forming engines 10Y, 10M, 10C and 10Bk.

  Further, when wear of each roller in the planetary reduction roller mechanism 50 progresses, the target rotational speed cannot be given to the photosensitive drum 11 even if the rotational speed of the drive motor M is finally increased. Therefore, this drive control device is configured to detect the slippage of the roller in the planetary reduction roller mechanism 50 and to determine the life of the planetary reduction roller mechanism 50 from the slippage. The slip amount in the planetary reduction roller mechanism 50 is grasped by comparing the input rotation speed and the output rotation speed. That is, the drive motor M is provided with the input side encoder 3 for detecting the rotation speed of the output shaft (the rotation speed of the sun roller 51), and the rotation control unit 2 reads the detection signal of the input side encoder 3. Thus, the input rotational speed to the planetary reduction roller mechanism 50 is grasped.

  FIG. 4 is a flowchart showing a processing procedure for determining the life of the planetary reduction roller mechanism 50. This processing procedure is executed when the rotation of the photosensitive drum 11, that is, the rotation of the drive motor M is started. First, the rotation control unit 2 reads the detection signal of the input side encoder 3 and rotates the output shaft of the drive motor M. The speed is grasped (ST1). Next, the rotation control unit 2 reads the detection signal of the output side encoder 60 and grasps the rotation speed of the output shaft 54 of the planetary decelerating roller mechanism 50 (ST2). Thereafter, the rotation control unit 2 compares the rotation speed of the output shaft of the drive motor M with the rotation speed of the output shaft 54 of the planetary reduction roller mechanism 50, and detects the slip amount in the planetary reduction roller mechanism 50 (ST3). Then, it is checked whether or not the slip amount is equal to or greater than a predetermined value (ST4). When the slip amount is less than the predetermined value, it is considered that the wear of each roller in the planetary speed reduction roller mechanism 50 has not yet progressed. Therefore, the drive motor continues to rotate for a certain period of time. Repeat ST1 to ST4 at intervals.

  On the other hand, when it is determined in ST4 that the slip amount is greater than or equal to the predetermined value, the rotation control unit 2 compares the rotation speed of the output shaft 54 detected in ST2 with the target rotation speed instructed from the control board 1 of the image forming apparatus. Then, it is checked whether or not they match (ST5). The rotational speed of the output shaft 54 of the planetary reduction roller mechanism 50 is feedback-controlled, and it takes some time until the rotational speed of the output shaft 54 matches the target rotational speed after the rotation of the drive motor M starts. Therefore, the check in ST5 is performed with a certain grace time, and it is checked whether or not the rotational speed of the output shaft 54 matches the target rotational speed within the grace time. As a result, if it is determined that they match, the rollers constituting the planetary reduction roller mechanism 50 are worn, but the output shaft 54 is within the usable rotation speed range of the drive motor M. Since the rotation speed can be matched with the target rotation speed, the rotation of the drive motor M is continued as it is, and the image forming operation is continued. Further, since the planetary speed reduction roller mechanism M is considered to have reached the end of its life due to the degree of wear, the rotation control unit 2 sends a request for replacing the planetary speed reduction roller mechanism 50 to the control board 1 of the image forming apparatus, that is, a warning signal. Notification is made (ST6). Upon receiving this replacement request, the control board 1 of the image forming apparatus displays the replacement request on the liquid crystal display panel 4 as a user interface, and warns the user. As a result, the user can notify the service engineer about the replacement of the planetary reduction roller mechanism 50 in a timely manner.

  In ST5, if the rotational speed of the output shaft 54 of the planetary speed reduction roller mechanism 50 does not match the target rotational speed instructed from the control board 1 even after a predetermined time has passed, the photosensitive drum 11 is moved to a predetermined process. Since the image cannot be rotated at the speed and a recorded image corresponding to the image information cannot be formed, the rotation control unit 2 immediately stops the drive motor M (ST7).

  Since the wear of each roller constituting the planetary speed reduction roller mechanism 50 gradually progresses and is unlikely to progress rapidly, the rotational speed of the output shaft 54 of the planetary speed reduction roller mechanism 50 and the target rotational speed instructed from the control board 1 This is because the excessive load is acting on the rotation of the photosensitive drum 11 as the rotated body for some reason, and slipping occurs in the planetary reduction roller mechanism 50 due to this. It is thought that there is. Accordingly, the rotation control unit 2 warns the control board 1 of the image forming apparatus that the drive motor M has been urgently stopped due to an overload (ST8), and the control board 1 receives this warning signal and receives another photoconductor. A control signal for instructing stop of the drive motor M is sent to all the photoconductor drive control devices including the drum 11. As a result, the image forming operation in all the image forming engines 10Y, 10M, 10C, and 10Bk is stopped. The control board 1 of the image forming apparatus receives the warning signal, displays a message indicating an emergency stop due to overload on the liquid crystal display panel 4 as a user interface, and gives a warning to the user.

  As described above, according to the rotational drive control device for the photosensitive drum of the present embodiment, it is possible to control the rotation of the photosensitive drum with high accuracy using the planetary reduction roller mechanism, and the planetary reduction roller mechanism. If it is determined that the recorded image corresponding to the image information cannot be formed due to the malfunction of the planetary speed reduction roller mechanism, the formation of the recorded image is immediately interrupted. A warning can be given to the user.

It is the schematic which shows the structure of the full color laser beam printer which can apply the rotational drive control apparatus of this invention. It is sectional drawing which shows an example of the planetary reduction roller mechanism used for the rotational drive of a photoconductor drum. 2 is a block diagram illustrating a configuration of a rotation drive control device provided for each photosensitive drum. FIG. It is a flowchart which shows the process sequence at the time of judging abnormality of a planetary reduction roller mechanism.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus side control board, 2 ... Rotation control part, 50 ... Planetary speed-reduction roller mechanism, M ... Drive motor

Claims (3)

A rotational drive control device for controlling the rotational speed of a rotating body included in an image forming apparatus,
A reduction roller mechanism that has a motor that rotates at a speed according to a control signal and a plurality of rollers that are in pressure contact with each other, transmits the rotation of the motor to the rotated body through these rollers while reducing the rotation, and the reduction roller mechanism A rotation control unit that compares a rotation speed of the output shaft with a target rotation speed to be given to the rotated body and sends a control signal to the motor so that the rotation speeds of the two coincide with each other;
The rotation control unit detects the slip amount of the speed reduction roller mechanism by comparing the rotation speed of the output shaft of the speed reduction roller mechanism and the rotation speed of the output shaft of the motor, and the slip amount becomes a predetermined value. A rotation drive control device that sends a warning signal to the control unit of the image forming apparatus when the value exceeds the limit. When the slip amount of the speed reduction roller mechanism exceeds a predetermined value, the rotation control unit checks whether or not the rotation speed of the output shaft of the speed reduction roller mechanism matches the target rotation speed. 2. The rotational drive according to claim 1, wherein if the two are matched, the rotational drive of the motor is continued and a warning signal notifying the malfunction of the speed reduction roller mechanism is sent to the controller of the image forming apparatus. Control device. When the slip amount of the speed reduction roller mechanism exceeds a predetermined value, the rotation control unit checks whether or not the rotation speed of the output shaft of the speed reduction roller mechanism matches the target rotation speed. 2. The rotational drive control according to claim 1, wherein the motor is stopped when it does not match for a predetermined time or more, and a warning signal notifying the overload of the rotated body is sent to the control unit of the image forming apparatus. apparatus.

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