JP4921902B2 - Rotating body drive control device, rotating body drive control method, program, and image forming apparatus - Google Patents

Description

  The present invention relates to a rotating body drive control device, a rotating body drive control method, a program, and an image forming apparatus that suppress fluctuations in rotational speed due to eccentricity of a rotating body and a drive source such as a motor that drives the rotating body.

  Conventionally, various devices using a motor that drives a rotating body to be controlled have been developed, and in order to improve processing accuracy of the device, the rotation speed of the motor in the apparatus and the rotation speed of the rotating body are controlled to be constant. Technology is being used.

  For example, an image forming apparatus equipped with a copying function, a printer function, a facsimile function, and the like includes a motor that drives a photosensitive drum, and detects the rotational angular displacement or rotational angular velocity of the rotation shaft of the motor, and detects it. A technique for feedback controlling the rotation of a motor based on the result is known. According to this method, by suppressing the rotation speed fluctuation of the motor and rotating it at a constant speed, image quality degradation such as image position shift and color shift caused by the rotation speed fluctuation of the photosensitive drum caused by the rotation speed fluctuation of the motor is reduced. Can be prevented.

  However, even if the motor is rotated at a constant speed, if there is an eccentricity on the rotating shaft of the photosensitive drum, a fluctuation in the rotational speed of one rotation period of the motor occurs in the photosensitive drum. On the other hand, in Patent Document 1, the rotational angular velocity is detected by an encoder attached to the rotation shaft of the photosensitive drum, and the rotation of the motor is rotated using the detected rotational speeds so that the photosensitive drum rotates at a stable speed. A technique for controlling the above has been proposed.

  Specifically, in the method of Patent Document 1, the rotation time when the photosensitive drum rotates at the specified rotation angle is observed at two locations, and the amplitude and phase of the speed fluctuation are obtained based on the passage time at the two locations. The rotation of the motor is controlled so as to suppress the speed fluctuation by the correction value calculated from the obtained amplitude and phase. This makes it possible to stabilize the rotational speed of the photosensitive drum even when the rotational axis of the photosensitive drum is eccentric. In Japanese Patent Laid-Open No. 2004-260, correction of rotational speed fluctuation caused by eccentricity of the photosensitive drum is performed, but fluctuation of rotational speed caused by eccentricity of the rotation shaft of the motor can also be corrected by a similar method. Conceivable.

JP 2005-94987 A

  However, since the eccentric component of the motor shaft generally has a higher frequency component than the eccentric component of the photosensitive drum, in order to detect the eccentric component of the motor shaft, the accuracy of the rotating plate for observing time must be increased. There was a problem of not becoming. In addition, it is technically very difficult to produce a highly accurate rotating plate, and even if it can be produced, it lacks practicality due to cost increase.

  The present invention has been made in view of the above, and is capable of detecting and suppressing a speed change due to eccentricity of a rotation shaft on a reduction gear input side such as a motor shaft without using a high-precision rotating plate. It is an object to provide a body drive control device, a rotating body drive control method, a program, and an image forming apparatus.

In order to solve the above-described problems and achieve the object, the invention according to claim 1 controls the rotation of the motor at a non-integer reduction ratio by controlling a drive signal for determining a voltage value to be supplied to the motor. Drive control means for controlling the rotational speed of a rotating body driven by a reduction gear that decelerates, and drive means for driving the motor by supplying the voltage value determined by the drive signal. The control means includes a first input means for inputting a first pulse generated when the motor makes one rotation, a second input means for inputting a second pulse generated when the rotor rotates once, and an input An amplitude and a phase of a change in the rotational speed of the rotating body caused by the eccentricity of the motor are calculated based on the second pulse, and based on the calculated amplitude and the phase. Correction value calculating means for calculating a correction value of the drive signal for suppressing the change, and calculating a time difference between the time when the first pulse is input and the time when the second pulse is input, and the calculated time difference Based on the specifying means for specifying the relationship between the rotation angle of the motor and the rotation angle of the rotating body, the first relationship that is the relationship specified when calculating the correction value, and after calculating the correction value The correction unit determines whether or not the second relationship that is the relationship specified at an arbitrary timing matches, and the correction at the timing when the second relationship determined to match the first relationship is specified. Output means for outputting the drive signal corrected by the value.

  According to a second aspect of the present invention, in the first aspect of the invention, the specifying unit may determine which of the calculated time differences is a reference time difference that is the time difference determined in advance corresponding to the reduction ratio. Determining whether to correspond to the reference time difference, and specifying the relationship corresponding to the reference time difference determined to correspond to the calculated time difference from the relationship corresponding to each of the reference time differences. To do.

  The invention according to claim 3 is the invention according to claim 2, wherein the specifying means is configured to determine whether the calculated first time difference is larger or smaller than the first time difference and the second time difference calculated before the first time difference. The relationship corresponding to the reference time difference in which the relationship and the magnitude relationship with respect to the other reference time difference are the same is specified.

  According to a fourth aspect of the present invention, in the second aspect of the invention, the specifying unit is configured to determine a difference between the calculated absolute value of the time difference and the absolute value of the reference time difference from a predetermined second threshold value. It is determined that the small reference time difference is the reference time difference corresponding to the calculated time difference, and the relationship corresponding to the reference time difference determined to correspond is specified.

  The invention according to claim 5 is the invention according to claim 2, wherein the specifying unit is configured to calculate a ratio of the calculated time difference to the pulse period of the first pulse and a ratio of the reference time difference to the pulse period. Determining the reference time difference having a difference smaller than a predetermined third threshold as the reference time difference corresponding to the calculated time difference, and specifying the relationship corresponding to the reference time difference determined to correspond; Features.

  The invention according to claim 6 further comprises storage means for storing information for identifying the identified first relationship in the invention according to claim 1, wherein the determination means is stored in the storage means. It is characterized by determining whether the said 1st relationship identified by information and the said 2nd relationship correspond.

  The invention according to claim 7 is the invention according to claim 1, wherein the first input means inputs the first pulse which is an FG (Frequency Generator) signal having a frequency corresponding to the rotational speed of the motor. It is characterized by doing.

  The invention according to claim 8 is the invention according to claim 1, wherein the first input means inputs the first pulse output from a rotary encoder that rotates coaxially with the motor. To do.

  The invention according to claim 9 is the invention according to claim 1, wherein the first input means inputs the first pulse output from a Hall element that detects a magnetic pole position of a magnet constituting the motor. It is characterized by this.

  The invention according to claim 10 is the invention according to claim 1, wherein the second input means outputs the second pulse output from a sensor that detects a rotation angle of a rotating plate that rotates coaxially with the rotating body. It is characterized by inputting.

The invention according to claim 11 is driven by a reduction gear that reduces the rotation of the motor at a non-integer reduction ratio by controlling a drive signal for determining a voltage value supplied to the motor by the drive control means. A drive control step for controlling the rotational speed of the rotating body, and a drive step for driving the motor by supplying the voltage value determined by the drive signal by a drive means, the drive control step comprising: A first input step for inputting a first pulse generated at a timing when the motor makes one rotation ; a second input step for inputting a second pulse generated at a timing when the rotor rotates once ; and the input Based on the second pulse, the amplitude and phase of the change in rotational speed of the rotating body caused by the eccentricity of the motor are calculated, A correction value calculating step of calculating a correction value of the drive signal that suppresses the change based on the amplitude and the phase; and a time difference between a time when the first pulse is input and a time when the second pulse is input. A specifying step of specifying a relationship between the rotation angle of the motor and the rotation angle of the rotating body based on the calculated time difference, and a first relationship that is the relationship specified when the correction value is calculated; A determination step for determining whether or not the second relationship, which is the relationship specified at an arbitrary timing after the correction value is calculated, and the second relationship determined to match the first relationship; And an output step of outputting the drive signal corrected with the correction value at the same timing.

  According to a twelfth aspect of the present invention, in the invention according to the eleventh aspect, the specific step is any one of the calculated time differences among the reference time differences that are the time differences determined in advance corresponding to the reduction ratio. Determining whether to correspond to the reference time difference, and specifying the relationship corresponding to the reference time difference determined to correspond to the calculated time difference from the relationship corresponding to each of the reference time differences. To do.

  The invention according to claim 13 is the invention according to claim 12, wherein, in the invention according to claim 12, the magnitude of the first time difference calculated before the first time difference is larger or smaller than the first time difference calculated. The relationship corresponding to the reference time difference in which the relationship and the magnitude relationship with respect to the other reference time difference are the same is specified.

  The invention according to claim 14 is the invention according to claim 12, wherein in the specifying step, the difference between the calculated absolute value of the time difference and the absolute value of the reference time difference is determined from a predetermined second threshold value. It is determined that the small reference time difference is the reference time difference corresponding to the calculated time difference, and the relationship corresponding to the reference time difference determined to correspond is specified.

  According to a fifteenth aspect of the present invention, in the invention according to the twelfth aspect, the specifying step includes calculating the ratio of the calculated time difference with respect to the pulse period of the first pulse and the ratio of the reference time difference with respect to the pulse period. Determining the reference time difference having a difference smaller than a predetermined third threshold as the reference time difference corresponding to the calculated time difference, and specifying the relationship corresponding to the reference time difference determined to correspond; Features.

  According to a sixteenth aspect of the present invention, in the invention according to the eleventh aspect, the determining step is identified by the information stored in storage means for storing information for identifying the specified first relationship. It is characterized by determining whether 1 relationship and the said 2nd relationship correspond.

  The invention according to claim 17 is the invention according to claim 11, wherein the first input step inputs the first pulse which is an FG (Frequency Generator) signal having a frequency corresponding to the rotational speed of the motor. It is characterized by doing.

  The invention according to claim 18 is the invention according to claim 11, wherein the first input step receives the first pulse output from a rotary encoder that rotates coaxially with the motor. To do.

  The invention according to claim 19 is the invention according to claim 11, wherein the first input step inputs the first pulse output from a Hall element that detects a magnetic pole position of a magnet constituting the motor. It is characterized by this.

  The invention according to claim 20 is the invention according to claim 11, wherein in the second input step, the second pulse output from a sensor that detects a rotation angle of a rotating plate that rotates coaxially with the rotating body. It is characterized by inputting.

  The invention according to claim 21 is a program that causes a computer to execute the rotating body drive control method according to any one of claims 11 to 20.

According to a twenty-second aspect of the present invention, there is provided an image forming apparatus for forming a toner image on a transfer medium, wherein the image forming apparatus is rotatably held, and is formed to be rotatably held with a conveying means for conveying the transfer medium. An image carrier that carries a toner image, a charging unit that uniformly charges the surface of the image carrier, and a latent image forming unit that forms a latent image on the surface of the image carrier that is uniformly charged by the charging unit A developing unit that visualizes the latent image formed by the latent image forming unit, a transfer unit that is rotatably held and transfers the toner image visualized by the developing unit to the transfer target, A rotating unit drive control device that controls driving of a motor that rotates at least one of a conveying unit, the image carrier, the intermediate transfer unit, and the transfer unit, and the rotating unit drive control unit includes a motor Drive that determines the voltage value to be supplied By controlling a rotation speed of a rotating body driven by a reduction gear that reduces the rotation of the motor by a non-integer reduction ratio, and the voltage value determined by the drive signal Drive means for driving the motor by supplying the drive control means, wherein the drive control means inputs a first pulse generated at a timing when the motor makes one rotation, and the rotating body makes one rotation. second input means for inputting a second pulse generated by the timing, the calculated amplitude of the change in the rotational speed of the rotating member and the phase caused by eccentricity of the motor based on the input the second pulse, calculated Correction value calculating means for calculating a correction value of the drive signal for suppressing the change based on the amplitude and the phase, and a time when the first pulse is input The time difference from the time when the second pulse is input is calculated, and based on the calculated time difference, the specifying means for specifying the relationship between the rotation angle of the motor and the rotation angle of the rotating body, and the correction value are calculated. Determining means for determining whether or not the first relationship which is the relationship specified at the time coincides with the second relationship which is the relationship specified at an arbitrary timing after calculating the correction value; Output means for outputting the drive signal corrected with the correction value at a timing when the second relationship determined to coincide with the relationship is specified.

  According to the present invention, there is an effect that it is possible to detect and suppress a speed change due to the eccentricity of the rotating shaft on the speed reducer input side such as a motor shaft without using a highly accurate rotating plate.

  Further, according to the present invention, the positional relationship between the motor and the rotating body is determined by an appropriate method according to the reduction gear ratio, and the speed due to the eccentricity of the rotating shaft on the reduction gear input side without using a high-precision rotating plate. There is an effect that the change can be detected and suppressed.

  Exemplary embodiments of a rotating body drive control device, a rotating body drive control method, a program, and an image forming apparatus according to the present invention will be explained below in detail with reference to the accompanying drawings.

(First embodiment)
The rotating body drive control device according to the first embodiment reduces the speed of the motor with a non-integer reduction gear ratio and rotates the photosensitive drum, thereby speeding not only the photosensitive drum axis but also the eccentricity of the motor axis. This is to correct for fluctuations. In addition, the relationship between the rotational position of the motor and the photosensitive drum when the correction value is calculated is stored, and when the positional relationship coincides, the motor is driven with the drive signal corrected by the correction value, thereby reducing the reduction gear ratio. This is to appropriately control the correction timing that may be shifted due to being a non-integer.

  In this embodiment, a so-called composite function including a copy function, a facsimile (FAX) function, a print function, a scanner function, and an input image (a document image read by the scanner function or an image input by the printer or the FAX function) is combined. An example applied to a rotating body drive control device that controls a motor provided in an image forming apparatus such as a digital multi-function peripheral called MFP (Multi Function Peripheral) will be described.

  FIG. 1 is a schematic configuration diagram illustrating an example of a mechanism unit of the image forming apparatus 10 according to the first embodiment. The image forming apparatus 10 can sequentially select a copying function, a printer function, and a facsimile function by operating an application switching key (not shown) of the operation unit. Thus, the copy mode is selected when the copy function is selected, the print mode is selected when the printer function is selected, and the facsimile mode is selected when the facsimile mode is selected.

  In this image forming apparatus 10, an image surface is placed on a document tray (also referred to as “document table”) 102 provided in an automatic document feeder (also referred to as “automatic document feeder”; hereinafter referred to as “ADF”) 101. When the start key on the operation unit is pressed in the copy mode, the document stack placed in a predetermined manner on the contact glass 105 by the feeding roller 103 and the feeding belt 104 sequentially one by one from the bottom document. It is fed to the position and set. The ADF 101 has a count function for counting up the number of documents every time one document is fed. The document set on the contact glass 105 is read by an image reading device (also referred to as “scanner” or “reading unit”) 106 constituting an image reading unit, and after the reading is completed, the feeding belt 104 is read. The paper is discharged onto the paper discharge tray 108 by the discharge roller 107.

  Each time reading of an image of one original is completed, an original set detector (also referred to as “original set detection sensor”) 109 detects whether or not the next original exists on the original tray 102. When the document set detector 109 detects that the next document is present on the document tray 102, the lowermost document on the document tray 102 is fed to the feed roller 103 and the feed in the same manner as the previous document. The sheet is fed to a predetermined position on the contact glass 105 by the feeding belt 104, and thereafter the same operation as described above is performed. The feeding roller 103, the feeding belt 104, and the discharging roller 107 are driven by a conveyance motor.

  When the first paper feeding device 110, the second paper feeding device 111, and the third paper feeding device 112 are selected, the first paper feeding tray 113, the second paper feeding tray 114, and the third paper feeding tray 115, respectively. The transfer paper (paper) loaded on the paper is fed, and the transfer paper is conveyed by the vertical conveyance unit 116 to a position where it abuts on the photoreceptor 117. As the photoconductor 117, for example, a photoconductor drum (hereinafter, referred to as a photoconductor drum 117) is used, and is driven to rotate by a main motor.

  Image data (image information) input by reading an image of a document by the image reading device 106 is subjected to predetermined image processing in an image processing unit (IPU), or is not illustrated as it constitutes an image storage unit. The image data is temporarily stored in the image memory, and then sent to a writing unit 118 constituting an image printing means (printer). The writing unit 118 converts the information into optical information, and the surface of the photosensitive drum 117 is not shown. After being uniformly charged by the device, it is exposed with light information from the writing unit 118 to form an electrostatic latent image. The electrostatic latent image on the photosensitive drum 117 is developed by a developing device (also referred to as “developing unit”) 119 to form a toner image.

  An image in which an image is formed on transfer paper by image data by an electrophotographic method using a photosensitive drum 117, a charger, a writing unit 118, a developing device 119, and other well-known devices around the photosensitive drum 117 not shown. A printer engine which is an image forming unit that performs a forming operation is configured. The conveyance belt 120 serves as a sheet conveyance unit and a transfer unit, and a transfer bias is applied from a power source. The conveyance belt 120 conveys the transfer sheet from the vertical conveyance unit 116 to the photosensitive drum 117 at a constant speed, and the toner on the photosensitive drum 117. Transfer the image to transfer paper. The transfer paper is fixed with a toner image by a fixing device 121 and is discharged to a paper discharge tray 123 by a paper discharge unit 122. A photosensitive drum 117, a charger, a writing unit 118, a developing device 119, a transfer unit, and an image forming unit that forms an image on transfer paper based on image data are configured.

  The above operation is an operation for copying an image on one side of the transfer paper in the normal mode. When copying an image on both sides of the transfer paper in the double-side mode, the first and second paper feed trays 113 are used. The transfer paper that has been fed from any one of -115 and on which the image is formed as described above is switched by the paper discharge unit 122 to the double-sided paper feed path 124 side, not the paper discharge tray 123 side, and is reversed. Switched back by the unit 125, the front and back sides are reversed, and conveyed to the duplex conveying unit 126.

  The transfer paper transported to the double-sided transport unit 126 is transported to the vertical transport unit 116 by the double-sided transport unit 126, transported to the position where it abuts on the photoconductive drum 117 by the vertical transport unit 116, and is transferred onto the photoconductive drum 117. The toner image formed in the same manner as above is transferred to the back surface, and the toner image is fixed by the fixing device 121, whereby double-sided copying is performed. This double-sided copy is discharged to the paper discharge tray 123 by the paper discharge unit 122. Further, when the transfer paper is reversed and discharged, the transfer paper that is switched back by the reversing unit 125 and turned upside down is not conveyed to the duplex conveying unit 126 but is discharged via the reverse discharge conveyance path 127. The paper is discharged to the paper discharge tray 123 by the unit 122.

  In the print mode, image data from the outside is input to the writing unit 118 instead of the image data from the image processing apparatus, and an image is formed on the transfer paper as described above. Further, in the facsimile mode, the image data from the image reading device 106 is transmitted to the other party by a facsimile transmission / reception unit (not shown), and the image data from the other party is received by the facsimile transmission / reception unit. By inputting the data to the writing unit 118 instead of data, an image is formed on the transfer paper as described above.

  The image forming apparatus 10 includes a large-volume paper supply device (hereinafter referred to as “LCT”), a finisher (post-processing device) that performs processing including sorting, punching, and stapling (not shown), A mode for reading an image of a document, setting of a copying magnification, setting of a paper feed stage, setting of post-processing by a finisher, various keys for displaying to an operator, and an operation unit having a display including an LCD are provided.

  The image reading apparatus 106 includes a contact glass 105 on which an original is placed and an optical scanning system. The optical scanning system includes various parts including an exposure lamp 128, a first mirror 129, a lens 132, and a CCD image sensor 133. ing. The exposure lamp 128 and the first mirror 129 are fixed on the first carriage (not shown), and the second mirror 130 and the third mirror 131 are fixed on the second carriage (not shown). When reading an image of a document, the first carriage and the second carriage are mechanically scanned at a relative speed of 2: 1 so that the optical path length does not change. The optical scanning system is driven by a drive unit including a scanner drive motor (not shown).

  The image reading device 106 optically reads an image of a document and converts it into an electrical signal (reads image data of the document). That is, the image surface of the document is illuminated by the exposure lamp 128 of the optical scanning system, and the reflected light image from the image surface is passed through the first mirror 129, the second mirror 130, the third mirror 131, and the lens 132, and the CCD image sensor. An image is formed on the light receiving surface 133 and converted into an electric signal by the CCD image sensor 133. At this time, by moving the lens 132 and the CCD image sensor 133 in the left-right direction in FIG. 1, the image reading magnification in the document feeding direction changes. That is, the left and right positions of the lens 132 and the CCD image sensor 133 are set in accordance with a preset image reading magnification.

  The writing unit 118 includes various parts including a laser output unit 134, an imaging lens 135, and a mirror 136. Inside the laser output unit 134 is a polygon mirror (rotated at a constant speed by a laser diode and a motor as a laser light source). Equipped with a rotating polygon mirror. A laser beam (laser light) emitted from the laser output unit 134 is deflected by a polygon mirror that rotates at a constant speed, passes through an imaging lens 135, is folded by a mirror 136, and is collected on a charging surface of the photosensitive drum 117. To form an image.

  That is, the laser beam deflected by the polygon mirror is exposed and scanned in a direction (main scanning direction) orthogonal to the direction in which the photosensitive drum 117 rotates, and writing of image data output from the image processing apparatus in units of lines. An electrostatic latent image is formed on the charged surface of the photosensitive drum 117 by repeating main scanning at a predetermined cycle corresponding to the rotational speed of the photosensitive drum 117 and the scanning density (recording density).

  Next, a control system centering on the main controller 40 of the image forming apparatus 10 according to the present embodiment will be described with reference to FIG.

  The image forming apparatus 10 includes a main controller 40 that controls the entire apparatus. The main controller 40 includes image processing for performing display for an operator, an operation unit 30 for performing function setting input control from the operator, control for a scanner, control for writing a document image in an image memory, control for image formation from the image memory, and the like. A unit (IPU) 49, an ADF (Auto Document Feeder) 101, and a distributed control device such as a finisher are connected. The operation unit 30 is connected to a liquid crystal touch panel 31, a numeric keypad 32, a clear / stop key 33, a print key 34, a preheat key 35, and the like. Each distributed controller and the main controller 40 exchange machine status and operation commands as necessary. A main motor 25 and various clutches 21 to 24 necessary for paper conveyance are also connected.

  In the present embodiment, the main controller 40 controls various motors provided in the image forming apparatus 10 such as the main motor 25 and the conveyance motor 26 through a motor control controller (rotary body drive control device). To do. The main controller 40 may be configured to include a rotating body drive control device. In the following, the details of the rotating body drive control device of the present embodiment will be described using the rotating body drive control device that is provided in the image forming apparatus 10 and controls the driving of various motors of the image forming apparatus 10 as an example. To do.

  The motor to be controlled is not limited to the main motor 25, and any motor in the image forming apparatus 10 can be the control target. Further, applicable rotary body drive control devices are not limited to those used in the image forming apparatus 10 such as a digital multi-function peripheral, and can be applied to motor control devices used in any apparatus.

  First, the control processing of the rotational speed of the photosensitive drum 117 by the conventional rotating body drive control device will be described. FIG. 3 is a block diagram showing a configuration of a conventional rotating body drive control device 300. As shown in the figure, the rotating body drive control device 300 is connected to a main motor (hereinafter referred to as a motor 25). In addition, a rotary encoder 142 that generates a pulse signal corresponding to the rotation of the motor 25 is connected to the motor 25 coaxially with the rotation shaft of the motor 25. The rotation of the motor 25 is transmitted to the photosensitive drum 117 via a reduction gear 141 having an integer gear ratio.

  As shown in the figure, the rotating body drive control device 300 includes a drive control unit 320 and a driver 330.

  The drive control unit 320 outputs a drive signal for controlling the drive of the motor 25 to the driver 330 in accordance with the rotation speed instruction value input from the main controller 40. Specifically, the drive control unit 320 compares the rotation of the motor 25 measured based on the rotational displacement signal input from the rotary encoder 142 with the rotational speed instruction value, and at the instructed speed, the motor 25. Is controlled to rotate.

  The driver 330 drives the motor 25 with a voltage value corresponding to the drive signal output from the drive control unit 320.

  In the rotating body drive control device 300 as shown in FIG. 3, for example, when the rotating shaft of the photosensitive drum 117 is eccentric, the surface speed of the photosensitive drum 117 cannot be kept constant only by the above-described rotational speed control process. . FIG. 4 is an explanatory view showing a state in which the rotation shaft of the photosensitive drum 117 is eccentric.

  As shown in the figure, when the rotating shaft of the photosensitive drum 117 is eccentric with respect to the center of the circle, the motor 25 always rotates at the angular velocity ω, and there is no rotation transmission error from the motor 25 to the drum shaft. Even so, the speeds V1 and V2 of the outer peripheral surfaces having different distances from the rotation axis of the photosensitive drum 117 are V1 ≠ V2, and the surface speed of the photosensitive drum 117 is not constant. Such a difference in the speed of the outer peripheral portion causes unevenness in the image, greatly affecting the quality of the formed image.

  In the rotating body drive control device 200 of the first embodiment, the rotation of the motor 25 can be controlled so as to suppress such fluctuations in the surface speed of the rotating body due to the eccentricity of the rotating shaft. FIG. 5 is a block diagram illustrating a configuration of the rotating body drive control device 200 according to the first embodiment. As shown in the drawing, in the first embodiment, a rotating plate 144 and a sensor 143 are connected to the photosensitive drum 117 in order to detect the rotational speed. Further, in order to be able to correct not only the speed fluctuation due to the eccentricity of the photosensitive drum 117 but also the speed fluctuation due to the eccentricity of the rotation shaft of the motor 25, the photosensitive drum 117 is rotated by the reduction gear 241 having a non-integer reduction ratio. Driven.

  The rotating plate 144 includes a detection element such as a slit at a predetermined rotation angle position. The sensor 143 outputs a pulse-like detection signal corresponding to the rotation of the rotating plate 144 by detecting the passage of the slit of the rotating plate 144 and outputting a signal.

  As shown in the figure, the rotating body drive control device 200 includes a drive control unit 220 and a driver 230.

  The driver 230 drives the motor 25 with a voltage value corresponding to the drive signal output from the drive control unit 220, like the driver 330 of the conventional rotating body drive control device 300.

  Similar to the drive control unit 320, the drive control unit 220 outputs a drive signal for controlling the drive of the motor 25 to the driver 230 in accordance with the rotation speed instruction value input from the main controller 40. Further, the drive control unit 220 receives a pulse signal corresponding to the rotation of the photosensitive drum 117 from the sensor 143, and uses the input pulse signal to change the rotational speed due to the eccentricity of the rotating shafts of the photosensitive drum 117 and the motor 25. , And a drive signal controlled to suppress fluctuations is output.

  Here, a method for correcting fluctuations in rotational speed due to eccentricity of the rotating shaft will be described. FIG. 6 is an explanatory diagram showing speed fluctuations on the surface of the photoconductive drum 117 when the rotation axis of the photoconductive drum 117 is decentered. The vertical axis of the graph in the figure is the speed, and the horizontal axis is the rotation angle. As shown in the figure, the speed is a sine wave centered on the speed without eccentricity with respect to the rotation angle (the amplitude is the amount of eccentricity). Proportional to the shape).

  FIG. 7 is an explanatory diagram showing an example of the sensor output when there is an eccentricity on the rotating shaft of the photosensitive drum 117. The figure shows an output pulse of the sensor 143 when rotation is detected using a rotating plate 144 having slits whose rotation angles are separated by 180 degrees (that is, a pulse is output every half rotation). As shown in the figure, two pulses are output in one revolution of the drum. In addition, the vertical axis of the graph of the same figure is a sensor output, and a horizontal axis is time.

By applying the method of Patent Document 1 from the pulse intervals t ₁ and t _{2 of} two pulses output in one rotation of the photosensitive drum 117, the phase and amplitude of the fluctuation component due to the eccentricity of the rotation axis of the photosensitive drum 117 are applied. Can be requested. That is, first, when the motor 25 is controlled to a target constant rotation speed, an interval between pulses generated every half rotation of the drum is detected. After that, when the motor 25 is controlled using the measurement sine wave reference signal that fluctuates in the drum rotation cycle as a new target, an interval of pulses generated every half drum rotation is detected. Based on these detection results, the amplitude and phase of the rotational speed fluctuation in one rotation period due to the eccentricity of the drum shaft are obtained.

  However, in the case of the apparatus configuration shown in FIG. 5 in which the reduction gear 241 is a transmission mechanism, the eccentricity of the rotation shaft can exist not only in the photosensitive drum 117 but also in the rotation shaft of the motor 25. FIG. 8 is an explanatory diagram showing the speed fluctuation of the surface of the photosensitive drum 117 when the rotation axis of the motor 25 is eccentric.

  This figure shows the speed fluctuation of the drum surface when there is no eccentricity of the rotating shaft of the photosensitive drum 117, only the eccentric component of the rotating shaft of the motor 25 is present, and the reduction gear ratio is 4: 1. It is a graph. In addition, the vertical axis of the graph of the figure is the speed, and the horizontal axis is the rotation angle.

  As shown in the figure, the rotation speed changes in a sine wave (amplitude is proportional to the amount of eccentricity) with the rotation period of the motor 25, with the rotation angle as the center, with respect to the rotation angle. In this example, since the reduction gear ratio is 4 to 1, one rotation of the drum includes four rotations of the motor 25.

  FIG. 9 is an explanatory diagram illustrating an example of a sensor output when there is an eccentricity on the rotation shaft of the motor 25. This figure shows an output pulse of the sensor 143 when rotation is detected using a rotating plate 144 having slits whose rotation angles are separated by 180 degrees. As shown in the figure, two pulses are output in one revolution of the drum. In addition, the vertical axis of the graph of the same figure is a sensor output, and a horizontal axis is time.

As shown in the figure, since the two slits are arranged on a diagonal line, the integrated passage time t ₁ for the first half 180 ° movement is equal to the passage time t _{2 for the second} half 180 °. Therefore, from the pulse times t ₁ and t ₂ , the amplitude and phase of the speed fluctuation relating to the eccentricity of the rotating shaft of the motor 25 cannot be calculated.

  Therefore, in the first embodiment, by setting the reduction gear ratio of the reduction gear 241 to a non-integer, the rotation plate 144 that rotates integrally with the drum rotation shaft and the stationary state with respect to the eccentricity of the rotation shaft of the motor 25 are fixed. It is possible to detect the speed fluctuation of the photosensitive drum 117 by using the same simple rotation detection means as the above comprising the sensor 143 on the side. For example, the gear ratio is such that the phase of the motor 25 is shifted 180 degrees by one rotation of the photosensitive drum 117, for example, a gear ratio of 2.5 to 1.

  The condition is that the fluctuation due to the eccentricity of the rotating shaft of the photosensitive drum 117 is corrected before the fluctuation due to the eccentricity of the rotating shaft of the motor 25 is corrected. This can be realized, for example, by the method of Patent Document 1 described above. In this way, after performing the rotational fluctuation correction control due to the eccentricity of the rotating shaft of the photosensitive drum 117, the next step is to detect the speed fluctuation due to the eccentricity of the rotating shaft of the motor 25 that could not be detected by this method. Do. The drum shaft eccentricity test is performed at the part level before the photosensitive drum 117 is incorporated into the apparatus, information unique to the photosensitive drum 117 is obtained in advance, and this information is used as control data. You may perform control which suppresses the speed fluctuation | variation by eccentricity of a drum axis | shaft.

  FIG. 10 is an explanatory diagram showing the speed fluctuation of the surface of the photosensitive drum 117 caused only by the eccentricity of the rotation shaft of the motor 25. In the figure, the reduction gear ratio is set to 2.5 to 1, the fluctuation due to the eccentricity of the rotating shaft of the photosensitive drum 117 is suppressed by the above-described method, and only the speed fluctuation due to the eccentricity of the rotating shaft of the motor 25 appears. This shows the speed fluctuation of the drum surface.

  In addition, the vertical axis of the graph of the figure is the speed, and the horizontal axis is the rotation angle. As shown in the figure, the rotation speed changes in a sine wave (amplitude is proportional to the amount of eccentricity) with the rotation period of the motor, with the rotation angle as the center, with respect to the rotation angle. In this example, since the reduction gear ratio is 2.5 to 1, the two rotations of the drum include the five rotations of the motor 25.

  FIG. 11 is an explanatory diagram illustrating an example of a sensor output when there is an eccentricity on the rotation shaft of the motor 25 in the same situation as FIG. FIG. 11 shows an output pulse of the sensor 143 when rotation is detected using a rotating plate 144 having slits whose rotation angles are separated by 180 degrees. As shown in the figure, two pulses are output in one revolution of the drum. In addition, the vertical axis of the graph of the same figure is a sensor output, and a horizontal axis is time.

In this case, as shown in the figure, since the speed fluctuation patterns of the first and second laps of the drum are different (see FIG. 10), the first round passage time t ₁ + t ₂ and the second round passage time t ₃ + t ₄ is not equal.

Therefore, the phase and amplitude of the speed fluctuation due to the eccentricity of the rotating shaft of the motor 25 can be obtained from the time relationship between the pulse intervals of t _{1 to} t ₄ . That is, for the phase and amplitude of the speed fluctuation due to the eccentricity of the rotation axis of the motor 25, a method similar to the detection method for the rotation fluctuation due to the eccentricity of the drum axis is applied, and the first and second pulses of the photosensitive drum 117 are applied. The difference in interval time (that is, the time difference of (t ₁ + t ₂ ) − (t ₃ + t ₄ ), or the time difference of (t ₁ −t ₃ ) is possible because t ₁ = t ₂ and t ₃ = t _4. ).

  As described above, in the first embodiment, since the phase and amplitude are obtained from the difference between the pulse interval times of the first and second rounds of the photosensitive drum 117, the slit on the rotating plate 144 is highly accurate. I don't need that. That is, using the obtained phase and amplitude, the drive control unit 220 can correct the motor shaft eccentricity to the rotation speed instruction value given from the main controller 40 and control the motor 25 based on the result. The photosensitive drum 117 can be controlled to rotate at a constant speed without using an expensive high-precision encoder.

  With the above method, in the first embodiment, not only the rotation shaft of the photosensitive drum 117 but also the fluctuation of the rotation speed due to the eccentricity of the rotation shaft of the motor 25 is corrected. However, it should be noted that in this method, correction control may not be performed normally unless the reference position of the pulse output for which the correction value is calculated is correctly recognized. The details of this problem and the solution will be described below.

  Here, for example, the reduction gear ratio is 1.5 to 1, and the speed due to the eccentricity of the rotating shaft of the motor 25 is based on the difference in time passing through the same slit on the first and second rounds of the photosensitive drum 117. Consider the case where fluctuations are calculated.

  FIG. 12 is an explanatory diagram showing an example of the amplitude and phase of the motor shaft eccentric component calculated in this case. In the figure, the position that has passed through the slit on the first round of the photosensitive drum 117 is represented as A. Further, the position where the second round of the photosensitive drum 117 has passed through the slit is indicated as B. As shown in the figure, the phase of the motor shaft eccentric component is shifted by 180 degrees between A and B.

  Since the rotation unevenness on the photosensitive drum 117 can be removed by driving and controlling the motor 25 with the detected antiphase component of the motor shaft eccentric component, the antiphase component control may be performed from the reference slit.

  FIG. 13 is an explanatory diagram showing the relationship between the motor shaft eccentric component, the antiphase component for controlling the motor 25, and the fluctuations in the rotational speed after correction. If the reference slit position can be set correctly, fluctuations in the rotational speed after correction can be suppressed as shown in FIG.

  However, the pulse output from the slit attached to the rotating shaft of the photosensitive drum 117 is the same pulse on the first and second rounds of the photosensitive drum 117. In other words, the reference position regarding the calculated motor shaft eccentricity component cannot be known from only the pulse output, and if the antiphase component control of the motor shaft eccentricity component is performed without being aware of the reference position, the correction is normally performed. It may not be possible.

  FIG. 14 is an explanatory diagram showing the relationship between the motor shaft eccentric component, the anti-phase component for controlling the motor 25, and the corrected rotational speed fluctuation in such a case. This figure shows an example in which the speed fluctuation is further increased because the reference position is set erroneously and is corrected with the anti-phase component that is 180 degrees out of phase. In such a case, instead of removing the rotation unevenness of the photoconductive drum 117, the length is increased on the contrary, thereby causing an image position shift or a color shift, thereby reducing the image quality.

  Therefore, in the first embodiment, in addition to the pulse output from the slit of the photosensitive drum 117, the pulse output from the rotary encoder 142 already used on the motor 25 side is monitored, and the difference between the two pulse detection times is monitored. Thus, the reference position of the photosensitive drum 117 is correctly determined.

  Below, the outline | summary of the method of implement | achieving this is demonstrated. Here, as a pulse of the motor 25, a pulse signal from the rotary encoder 142 that outputs one pulse for each rotation of the motor 25 is used. Note that the pulse output of the motor 25 may be any one that generates one or more pulses for each rotation of the motor 25. Further, the reduction gear ratio is assumed to be 1.5 to 1, and one pulse is output every rotation of the photosensitive drum 117.

  FIG. 15 is an explanatory diagram showing a pulse output timing when a pulse having the above-described configuration is output when there is no motor shaft eccentricity. As shown in the figure, each time the motor 25 and the photosensitive drum 117 rotate, the number of pulses output is one. Also, since the reduction gear ratio is 1.5 to 1, the number of pulses (rotary encoder pulses) of the rotary encoder 142 that are output while the photosensitive drum 117 makes two revolutions is three. The number of pulses output from 117 is two.

FIG. 16 is an explanatory diagram showing an example of a time difference between pulses. As shown in the figure, if the pulse output of the first round of the photosensitive drum 117 and the generation of the rotary encoder pulse are simultaneous, the time difference t ₀ is “0”. Further, the second lap and the pulse output of the photosensitive drum 117, occurrence time difference of the rotary encoder pulse, when the pulse interval of the rotary encoder pulse and t _r, the time difference t ₁ is "t _r / 2".

  Thus, when the reduction gear ratio is a non-integer multiple, a time difference always occurs between the pulse generation timing on the motor 25 side and the pulse generation timing on the photoconductor drum 117 side. That is, when the motor shaft eccentric component is calculated, the relationship between the relationship between the pulse of the photosensitive drum 117 and the pulse on the motor 25 that is used as a reference at the time of calculation is managed in combination. The reference pulse for performing the correction control can be accurately recognized, and the rotation speed of the photosensitive drum 117 can be kept constant.

  In the first embodiment, the drive control unit 220 performs processing for recognizing a reference pulse by the method as described above. FIG. 17 is a block diagram showing a detailed configuration of the drive control unit 220 in the first embodiment. As shown in the figure, the drive control unit 220 includes a first input unit 221, a second input unit 222, a correction value calculation unit 223, a specifying unit 224, a storage unit 225, a determination unit 226, and a PWM. And an output unit 227.

  The first input unit 221 inputs a pulse generated by the rotary encoder 142 according to the rotation of the motor 25. The second input unit 222 inputs a pulse generated by the sensor 143 according to the rotation of the photosensitive drum 117.

  The correction value calculation unit 223 uses the pulse input to the second input unit 222 to detect fluctuations in the rotational speed of the rotating body of the photosensitive drum 117 caused by the eccentricity of the motor 25 by the method of Patent Document 1 as described above. The amplitude and phase are calculated, and the correction value of the drive signal that suppresses the rotational speed fluctuation is calculated.

  The specifying unit 224 specifies the relationship between the rotation angle of the motor 25 and the rotation angle of the photosensitive drum 117 from the time difference between the pulse generated by the rotary encoder 142 and the pulse generated by the sensor 143. Specifically, the specifying unit 224 calculates a time difference from the rotary encoder pulse when the motor shaft eccentric component is calculated to the pulse of the photosensitive drum 117, and the calculated time difference is a reference that is determined according to the reduction gear ratio. The relationship between the rotation angle of the motor 25 and the rotation angle of the photosensitive drum 117 corresponding to each of the reference time differences is specified depending on which of the time differences corresponds.

Here, the reference time difference refers to each value that can be taken by the time difference between pulses determined by the reduction gear ratio. For example, when the reduction gear ratio is 1.5 to 1 as shown in FIG. 16, the value that can be taken as the time difference is t ₀ (= 0) or t ₁ (= t _r / 2), so the reference time difference is t ₀ difference or t ₁ .

In this case, at the reference time difference t ₀ , it can be specified that the rotation angle at which the rotary encoder 142 generates a pulse and the rotation angle at which the sensor 143 generates a pulse have a matching relationship. In addition, at the reference time difference t ₁ , it can be specified that the rotation angle when the rotary encoder 142 generates a pulse and the rotation angle when the sensor 143 generates a pulse are in a relationship of 180 degrees.

Further, in the first embodiment, the specifying unit 224 determines that the magnitude relationship of the calculated time difference with respect to the time difference calculated at the previous pulse is larger or smaller than the other reference time difference of the two reference time differences (larger). The reference time difference corresponding to the determined reference time difference is determined by obtaining a reference time difference that is the same as a value or a small value. For example, when the reduction gear ratio is 1.5 to 1 as described above, since the reference time difference t ₀ = 0 and the reference time difference t ₁ = t _r / 2, the calculated time difference is calculated at the time of the previous pulse. If it is relatively large with respect to the calculated time difference, it can be determined that the reference time difference is t ₁ which is the larger value.

The determination of the magnitude relationship may be made based on the magnitude relationship with respect to a predetermined threshold. For example, when the threshold is set to 0 and the time difference is equal to the threshold, it is determined that the reference time difference is t ₀ . When the time difference is larger than the threshold value, it is determined that the reference time difference t ₁ .

The storage unit 225 stores information for identifying the relationship specified by the specifying unit 224 when the correction value is calculated. For example, the storage unit 225 indicates a time difference magnitude relationship (large value or small value), a determined reference time difference (t ₀ or t ₁ ), or a specified rotation angle relationship (match or 180 ° phase shift). And stored as information for identifying the specified relationship. Information when the correction value stored in this way is calculated is referred to as a comparison target when determining the timing at which the determination unit 226 outputs the drive signal corrected with the correction value.

  The determination unit 226 refers to the information stored in the storage unit 225, and specifies the relationship specified by the specifying unit 224 when calculating the correction value and the specifying unit 224 when outputting the drive signal corrected with the calculated correction value. It is determined whether or not the relationship specified by is coincident. In the first embodiment, the determination unit 226 determines whether the specified relationship matches based on whether the magnitude relationship at the time of correction value calculation matches the magnitude relationship at the time of driving signal output.

  The PWM output unit 227 outputs a PWM signal as a drive signal for driving and controlling the motor 25 according to the rotation speed instruction value input from the main controller 40. When the correction value for the speed fluctuation due to the eccentricity of the rotation axis of the motor 25 or the photosensitive drum 117 is calculated, a PWM signal corrected with the correction value is output. At this time, the PWM output unit 227 outputs the PWM signal corrected with the correction value at the timing when the determination unit 226 determines that the relationship is the same.

  Next, the hardware configuration of the drive control unit 220 will be described. FIG. 18 is a block diagram illustrating a hardware configuration of the drive control unit 220. As shown in the figure, the drive control unit 220 includes a CPU (Central Processing Unit) 501, a ROM (Read Only Memory) 502, a RAM (Random Access Memory) 503, a timer 504, and a general-purpose input port 505. I have.

  The CPU 501 is a part that performs arithmetic processing such as measurement of the input pulse interval time and processing for obtaining the amplitude and phase of the motor shaft eccentricity. The ROM 502 stores control programs, fixed parameters, data, and the like. The RAM 503 is used as a work area for temporarily storing and calculating the measured pulse interval time.

  The timer 504 is used to control the motor rotation speed, and generates a basic clock (PWM clock) for rotating the motor 25 and supplies it to the driver 230. The driver 230 performs an operation of rotating the motor 25 in synchronization with the supplied PWM clock.

  The general-purpose input port 505 is for inputting two or more pulses from the outside. For example, the pulse 1 input and the pulse 2 input in FIG. 4 mean that a pulse from the rotary encoder 142 and a pulse from the sensor 143 are input, respectively.

  The change point of two or more pulses input to the general-purpose input port 505 is monitored by a program, and the interval is measured by a counter by software. The general-purpose input port 505 is provided with a dedicated circuit so that each time a change point occurs in an external pulse, the time interval of the pulse is measured by the circuit, and the program uses the measurement time result. May be. Further, the hardware configuration shown in the figure is not applied only to the drive control unit 220, and the main controller 40 may be included in the hardware configuration.

  Next, the rotating body drive process by the rotating body drive control apparatus 200 according to the first embodiment configured as described above will be described. FIG. 19 is a flowchart illustrating an overall flow of the rotating body driving process according to the first embodiment.

  First, the PWM output unit 227 starts driving the motor 25 with the rotation speed instruction value from the main controller 40 (step S1901). Next, the first input unit 221 inputs a pulse from the rotary encoder 142 (step S1902). Similarly, the second input unit 222 inputs a pulse from the sensor 143 (step S1903).

  Next, the correction value calculation unit 223 calculates the amplitude and phase of speed fluctuation due to eccentricity using the pulse input to the second input unit 222 (step S1904). Next, the correction value calculation unit 223 calculates a rotation correction value for correcting the rotation of the motor 25 from the calculated amplitude and phase (step S1905).

  Next, the specifying unit 224 specifies the relationship between the rotation angle of the motor 25 and the rotation angle of the photosensitive drum 117 from the time difference between pulses when the correction value is calculated. Here, the specifying unit 224 calculates a time difference between pulses, and stores information indicating a magnitude relationship with respect to the previously calculated time difference in the storage unit 225 (step S1906). For example, as shown in FIG. 16, when the reduction gear ratio is 1.5 to 1 and the calculated time difference is larger than the time difference calculated at the previous pulse, information indicating that the value is large as the magnitude relationship. Save in the storage unit 225.

  Next, the determination unit 226 performs a rotational position detection process for determining the timing (rotational position) for outputting the drive signal corrected with the correction value (step S1907). Details of the rotational position detection process will be described later.

  After the output timing is detected in the rotation position detection process, the PWM output unit 227 corrects the rotation speed instruction value with the rotation correction value and outputs a drive signal for driving the motor 25 (step S1908). Thereafter, by repeating the processing from step S1902 onward, the drive control processing of the motor 25 is realized so as to suppress fluctuations in the rotational speed.

  Next, details of the rotational position detection processing in step S1907 will be described. FIG. 20 is a flowchart illustrating an overall flow of the rotational position detection process according to the first embodiment.

  First, the determination unit 226 initializes a timer value for measuring the time difference between pulses (step S2001). Next, the determination unit 226 determines whether or not a pulse from the rotary encoder 142 has been input (step S2002), and if it has been input (step S2002: YES), starts a timer count (step S2003).

  If no pulse is input from the rotary encoder 142 (step S2002: NO), the determination process of step S2002 is repeated until it is input.

  Next, the determination unit 226 determines whether or not a pulse from the sensor 143 has been input (step S2004). If the pulse has been input (step S2004: YES), the timer count is stopped and the counter value is stored. (Step S2005).

  If no pulse is input from the sensor 143 (step S2004: NO), the determination process of step S2004 is repeated until it is input.

Next, the determination unit 226 determines the magnitude relationship between the stored counter value and the counter value stored in the previous pulse (step S2006). For example, if the counter value stored in the previous pulse is 0 and the counter value stored in step S2005 is t ₁ (= t _r / 2), it is determined that the magnitude relationship is “large value”. To do.

  Next, the determination unit 226 determines whether the magnitude relationship at the time of calculating the correction value stored in the storage unit 225 matches the determined magnitude relationship (step S2007). For example, when information indicating “large value” is stored in the storage unit 225 and the determined magnitude relationship also indicates “large value”, the determination unit 226 determines that the two match. To do.

  If it is determined that they do not match (step S2007: NO), the process returns to step S2001 and is repeated. If it is determined that they match (step S2007: YES), the rotational position detection process ends.

  By such processing, the output timing of the pulse at the same position as the reference position of the pulse when the correction value is calculated can be determined, so that the drive signal corrected with the correction value can be output at the correct timing. It becomes. As a result, it is possible to avoid increasing rotation unevenness and degrading image quality.

  In the above description, the rotary encoder 142 is used to detect the rotation of the motor 25, but an FG signal of a DC brushless motor may be used instead of the rotary encoder 142. The FG signal is usually used for speed control of the motor 25, and many tens of pulses are output per rotation of the motor 25. By monitoring the time between the FG signal and the pulse signal of the photosensitive drum 117, the reference position of the photosensitive drum 117 can be specified from the difference.

  Similarly, instead of the FG signal, a pulse signal output from a Hall element or Hall IC that detects the magnetic pole position of the magnet constituting the motor 25 may be used. By using an FG signal, a Hall element, or the like, the above-described function can be realized at low cost without providing a special circuit or mechanism.

  Further, the pulse signal for specifying the reference position of the photosensitive drum 117 is not limited to the above as long as it is periodically output every rotation of the motor 25, and two or more plural pulses are used. It is also possible to use in combination.

  Thus, in the rotating body drive control device according to the first embodiment, a correction signal that calculates the motor shaft eccentric component without using an expensive high-precision encoder or the like and removes the calculated motor shaft eccentric component. Can be correctly reflected in the motor control, and as a result, image position shift and color shift can be reduced and improved.

(Second Embodiment)
In the first embodiment, the relationship between the rotation angle of the motor and the rotation angle of the photosensitive drum is specified by determining the magnitude relationship of the time difference between pulses. In this method, it is necessary to calculate a time difference in a plurality of consecutive cycles and determine a magnitude relationship between the calculated time differences. For example, when the reduction ratio is 1.25 to 1, there are four possible time difference values, so it is necessary to determine the magnitude relationship by calculating four consecutive time differences. For this reason, the processing time and burden until the reference position is specified are large.

  The rotating body drive control device according to the second embodiment uses the absolute value of the time difference and the ratio of the time difference to the pulse interval to calculate the rotation angle of the motor and the rotation angle of the photosensitive drum by calculating the time difference once. It is possible to specify the relationship.

  FIG. 21 is a block diagram illustrating a configuration of a rotating body drive control device 2100 according to the second embodiment. As shown in the figure, the rotating body drive control device 2100 includes a drive control unit 2120 and a driver 230.

  In the second embodiment, the function of the drive control unit 2120 is different from that of the first embodiment. Other configurations and functions are the same as those in FIG. 5, which is a block diagram showing the configuration of the rotating body drive control device 200 according to the first embodiment. .

  FIG. 22 is a block diagram illustrating a detailed configuration of the drive control unit 2120 according to the second embodiment. As shown in the figure, the drive control unit 2120 includes a first input unit 221, a second input unit 222, a correction value calculation unit 223, a specifying unit 2124, a storage unit 225, a determination unit 2126, a PWM And an output unit 227.

  In the second embodiment, the functions of the specifying unit 2124 and the determining unit 2126 are different from those of the first embodiment. Since other configurations and functions are the same as those in FIG. 17 which is a block diagram showing the configuration of the drive control unit 220 according to the first embodiment, the same reference numerals are given and description thereof is omitted here.

  The specifying unit 2124 determines which reference time difference the calculated time difference corresponds to by comparing the absolute value of the calculated time difference with the absolute value of the reference time difference that is the time difference at the time of calculating the correction value. is there. For example, when the reduction gear ratio is 1.25 to 1, the reference time difference can take four values. The specifying unit 2124 compares the absolute value of the four reference time differences with the calculated absolute value of the time difference, and specifies the corresponding reference time difference.

  FIG. 23 is an explanatory diagram showing the relationship of the output timing between the rotary encoder pulse output and the rotary plate pulse output when the reduction gear ratio is 1.25: 1.

If the first output timings of the rotary encoder pulse and the rotary plate pulse are simultaneous, that is, the pulse time difference t ₀ = 0, the second rotary plate pulse output timing is a time delayed by t ₁ from the rotary encoder pulse output. The t _1, when the rotary encoder pulse output interval and t _r, the _{t 1 = t r × 1.25-} t r = t r × (1.25-1) = t r × 0.25.

That is, t ₁ is generated with a delay of 25% with respect to the rotary encoder period. Similarly, t ₂ = t _r × 0.5 and t ₃ = t _r × 0.75.

In the second embodiment, which rotation plate pulse is the reference is determined by the absolute value of the pulse time difference. Here, the cycle for driving the motor 25 is determined by a value necessary for the control system. That is, since the _tr time is fixed, the calculated t ₀ to t ₃ values have a fixed value. These t _{0 to} t ₃ correspond to four possible values of the reference time difference.

For example, if the pulse interval _tr is 100 ms, the absolute value of the time difference can be determined such that t ₀ = 0, t ₁ = 25 ms, t ₂ = 50 ms, t ₃ = 75 ms.

Therefore, it is not necessary to compare the values between the calculated t ₀ ~t _3, only be compared with the absolute value for determination is made in advance understand in relation to the t _r time, knowing the reference pulse Can do. Thus, the reference pulse can be recognized in the shortest time without waiting for the drive source to make four turns.

Instead of using the absolute value of the time difference may be configured to recognize the reference pulse of the rotation plate 144 from the time ratio between t _r time and t ₀ ~t _3. As described above, with respect to t ₀ ~t ₃ are each t _r, 0% 25% change in 50%, 75% ratio. By using such a ratio, it is possible to recognize the reference pulse position of the rotating plate 144 even when the motor 25 is not a control system that always rotates at a constant speed.

  Thus, for example, when the reduction gear ratio is 1.25 to 1, the phase with the motor 25 is shifted 90 degrees in one rotation of the photosensitive drum 117, and the phase with the motor 25 is matched in four rotations of the photosensitive drum 117. To do. Therefore, in such a configuration, four different values are obtained for the pulse interval between the pulse of the motor 25 and the pulse on the rotating shaft side of the photosensitive drum 117. In the second embodiment, the reference position is specified by the absolute value of such four values or the ratio to the rotary encoder period.

  Note that there may be errors in the calculation of absolute values and ratios, so there is no need to determine whether the values match exactly, depending on whether the difference between the values to be compared falls within a predetermined threshold. A corresponding reference position is specified. Further, the phase shift amount for each rotation between the photosensitive drum 117 and the motor 25 is not limited to 180 degrees or 90 degrees, and any number of configurations may be used. Furthermore, the determination method for specifying the reference position is not limited to the determination of the absolute value or the ratio of the obtained values, and any method can be applied as long as the reference position can be uniquely specified.

  Returning to FIG. 22, as in the determination unit 226 of the first embodiment, the determination unit 2126 has a relationship specified by the specifying unit 2124 when calculating the correction value and a relationship specified by the specifying unit 2124 when outputting the drive signal. It is determined whether they match. In the second embodiment, the determination unit 2126 determines whether or not the specified relationship is identical depending on whether or not the absolute value of the reference time difference when calculating the correction value matches the absolute value of the reference time difference when outputting the drive signal. to decide.

  Next, the rotating body drive control process by the rotating body drive control apparatus 2100 according to the second embodiment configured as described above will be described. FIG. 24 is a flowchart illustrating an overall flow of the rotating body drive control process according to the second embodiment.

  The motor drive process, pulse input process, and correction value calculation process from step S2401 to step S2405 are the same as those from step S1901 to step S1905 in the rotating body drive control apparatus 200 according to the first embodiment. Description is omitted.

After calculating the correction value, the specifying unit 2124 calculates the time difference between pulses, and stores the absolute value of the time difference (hereinafter referred to as a reference counter value) in the storage unit 225 (step S2406). For example, as shown in FIG. 23, if the reduction gear ratio is 1.25 to 1, the pulse interval _tr is 100 ms, and the time is t ₁ , t ₁ = 25 ms is stored as the reference counter value.

  Next, the determination unit 2126 executes a rotational position detection process for determining the timing (rotational position) at which the drive signal corrected with the correction value is output (step S2407). Details of the rotational position detection process will be described later.

  The motor driving process based on the correction value in step S2408 is the same as that in step S1908 in the rotating body drive control apparatus 200 according to the first embodiment, and a description thereof will be omitted.

  Next, details of the rotational position detection processing in step S2407 will be described. FIG. 25 is a flowchart illustrating an overall flow of the rotational position detection process according to the second embodiment.

  The counter value storage process from step S2501 to step S2505 is the same as the process from step S2001 to step S2005 in the rotating body drive control apparatus 200 according to the first embodiment, and thus description thereof is omitted.

  After storing the counter value, the determination unit 2126 compares the stored counter value with the reference counter value stored in the storage unit 225, and determines whether the two values are equal (step S2506). If they are not equal (step S2506: NO), the process returns to step S2501 and is repeated. If equal (step S2506: YES), the rotational position detection process is terminated.

  As described above, in the rotating body drive control device according to the second embodiment, the reference position is identified in the shortest time because the reference position of the pulse is determined using the absolute value of the time difference and the ratio of the time difference to the pulse interval. can do.

  The program executed by the rotating body drive control device according to the first and second embodiments is provided by being incorporated in advance in a ROM or the like.

  A program executed by the rotating body drive control device according to the first and second embodiments is a file in an installable format or an executable format, and is a CD-ROM, a flexible disk (FD), a CD-R, a DVD. (Digital Versatile Disk) or the like may be provided by being recorded on a computer-readable recording medium.

  Further, the program executed by the rotating body drive control device according to the first and second embodiments is stored on a computer connected to a network such as the Internet, and is provided by being downloaded via the network. It may be configured. Moreover, you may comprise so that the program run with the rotary body drive control apparatus concerning 1st and 2nd embodiment may be provided or distributed via networks, such as the internet.

  The program executed by the rotating body drive control device according to the first and second embodiments includes the above-described units (first input unit, second input unit, correction value calculation unit, identification unit, determination unit). It has a module configuration, and as actual hardware, a CPU (processor) reads the program from the ROM and executes it, so that the above-mentioned units are loaded onto the main storage device, and the above-mentioned units are generated on the main storage device. It has become so.

  As described above, the rotating body drive control device, the rotating body drive control method, the program, and the image forming apparatus according to the present invention provide a rotating body drive control device and a rotating body drive that suppress fluctuations in rotational speed due to eccentricity of the rotating shaft. It is suitable for a control method, a program, and an image forming apparatus.

1 is a schematic configuration diagram illustrating an example of a mechanism unit of an image forming apparatus according to a first embodiment. 2 is a block diagram illustrating a configuration of a main controller of the image forming apparatus. FIG. It is a block diagram which shows the structure of the conventional rotary body drive control apparatus. It is explanatory drawing which shows the state in which the rotating shaft of the photoconductor drum was eccentric. It is a block diagram which shows the structure of the rotary body drive control apparatus concerning 1st Embodiment. FIG. 6 is an explanatory diagram illustrating speed fluctuations on the surface of the photosensitive drum when there is an eccentricity on the rotating shaft of the photosensitive drum. It is explanatory drawing which shows an example of the sensor output in case eccentricity exists in the rotating shaft of a photoconductive drum. It is explanatory drawing showing the speed fluctuation of the surface of a photoreceptor drum in case eccentricity exists in the rotating shaft of a motor. It is explanatory drawing which shows an example of the sensor output in case eccentricity exists in the rotating shaft of a motor. FIG. 6 is an explanatory diagram showing speed fluctuations on the surface of the photosensitive drum caused only by the eccentricity of the rotation shaft of the motor. It is explanatory drawing which shows an example of the sensor output in case eccentricity exists in the rotating shaft of a motor. It is explanatory drawing which shows an example of the amplitude and phase of a motor shaft eccentric component. It is explanatory drawing which shows the relationship between a motor shaft eccentric component, the antiphase component for controlling a motor, and the fluctuation | variation of the rotational speed after correction | amendment. It is explanatory drawing which shows the relationship between a motor shaft eccentric component, the antiphase component for controlling a motor, and the fluctuation | variation of the rotational speed after correction | amendment. It is explanatory drawing which showed the pulse output timing when motor shaft eccentricity does not exist. It is explanatory drawing which showed an example of the time difference between pulses. It is the block diagram which showed the detailed structure of the drive control part in 1st Embodiment. It is a block diagram which shows the hardware constitutions of a drive control part. It is a flowchart which shows the whole flow of the rotary body drive process in 1st Embodiment. It is a flowchart which shows the whole flow of the rotation position detection process in 1st Embodiment. It is a block diagram which shows the structure of the rotary body drive control apparatus concerning 2nd Embodiment. It is the block diagram which showed the detailed structure of the drive control part in 2nd Embodiment. It is explanatory drawing which showed the relationship of the output timing between a rotary encoder pulse output and a rotary plate pulse output. It is a flowchart which shows the whole flow of the rotary body drive control process in 2nd Embodiment. It is a flowchart which shows the whole flow of the rotation position detection process in 2nd Embodiment.

Explanation of symbols

10 Image forming apparatus 21, 22, 23, 24 Clutch 25 Main motor (motor)
26 transport motor 30 operation unit 31 liquid crystal touch panel 32 numeric keypad 33 clear / stop key 34 print key 35 preheat key 40 main controller 102 document tray 103 feed roller 104 feed belt 105 contact glass 106 image reading device 107 discharge roller 108 paper discharge Stand 109 Document set detector 110 First sheet feeder 111 Second sheet feeder 112 Third sheet feeder 113 First sheet tray 114 Second sheet tray 115 Third sheet tray 116 Vertical transport unit 117 Photosensitive drum (Photoconductor)
118 Writing Unit 119 Developing Device 120 Conveying Belt 121 Fixing Device 122 Paper Discharging Unit 123 Paper Discharging Tray 124 Double-Sided Paper Conveying Path 125 Reversing Unit 126 Double-Sided Conveying Unit 127 Reversing Paper Discharge Conveying Path 128 Exposure Lamp 129 First Mirror 130 Second Mirror 131 Third mirror 132 Lens 133 CCD image sensor 134 Laser output unit 135 Imaging lens 136 Mirror 141 Reduction gear 142 Rotary encoder 143 Sensor 144 Rotating plate 200 Rotating body drive control device 220 Drive control unit 221 First input unit 222 Second input Unit 223 correction value calculation unit 224 identification unit 225 storage unit 226 determination unit 227 PWM output unit 230 driver 241 reduction gear 300 rotating body drive control device 320 drive control unit 330 Liver 501 CPU
502 ROM
503 RAM
504 timer 505 general-purpose input port 2100 rotating body drive control device 2120 drive control unit 2124 specifying unit 2126 determination unit

Claims (22)

Drive control means for controlling the rotational speed of a rotating body driven by a reduction gear that reduces the rotation of the motor at a non-integer reduction ratio by controlling a drive signal for determining a voltage value supplied to the motor;
Drive means for driving the motor by supplying the voltage value determined by the drive signal;
The drive control means includes
First input means for inputting a first pulse generated at a timing when the motor makes one rotation ;
Second input means for inputting a second pulse generated at a timing when the rotating body makes one rotation ;
The drive signal that calculates the amplitude and phase of the change in rotational speed of the rotating body caused by the eccentricity of the motor based on the input second pulse, and suppresses the change based on the calculated amplitude and phase. Correction value calculating means for calculating the correction value of
The time difference between the time when the first pulse is input and the time when the second pulse is input is calculated, and the relationship between the rotation angle of the motor and the rotation angle of the rotating body is specified based on the calculated time difference. Specific means,
Judgment whether or not the first relationship that is the relationship specified when the correction value is calculated matches the second relationship that is the relationship that is specified at an arbitrary timing after the correction value is calculated Means,
Output means for outputting the drive signal corrected with the correction value at a timing at which the second relationship determined to match the first relationship is specified;
A rotating body drive control device comprising: The specifying means determines which reference time difference the calculated time difference corresponds to among the reference time differences, which are the time differences determined in advance corresponding to the reduction ratio, and corresponds to each of the reference time differences. Identifying the relationship corresponding to the reference time difference determined to correspond to the calculated time difference from the relationship to
The rotating body drive control device according to claim 1. The specifying means, for the calculated first time difference, the reference relationship in which the magnitude relation between the first time difference and the second time difference calculated before the first time difference is the same as the magnitude relation with respect to the other reference time differences. Identifying the relationship corresponding to the time difference;
The rotating body drive control device according to claim 2. The specifying means is the reference time difference corresponding to the calculated time difference, wherein the difference between the calculated absolute value of the time difference and the absolute value of the reference time difference is smaller than a predetermined second threshold value. Identifying the relationship corresponding to the reference time difference determined to correspond,
The rotating body drive control device according to claim 2. The specifying unit calculates the reference time difference in which a difference between the ratio of the calculated time difference with respect to the pulse period of the first pulse and the ratio of the reference time difference with respect to the pulse period is smaller than a predetermined third threshold value. Determining the reference time difference corresponding to the time difference and identifying the relationship corresponding to the reference time difference determined to correspond;
The rotating body drive control device according to claim 2. Storage means for storing information for identifying the identified first relationship;
The determination means determines whether the first relationship identified by the information stored in the storage means matches the second relationship;
The rotating body drive control device according to claim 1. The first input means inputs the first pulse which is an FG (Frequency Generator) signal having a frequency corresponding to the rotational speed of the motor.
The rotating body drive control device according to claim 1. The first input means inputs the first pulse output from a rotary encoder that rotates coaxially with the motor;
The rotating body drive control device according to claim 1. The first input means inputs the first pulse output from a Hall element that detects a magnetic pole position of a magnet constituting the motor;
The rotating body drive control device according to claim 1. The second input means inputs the second pulse output from a sensor that detects a rotation angle of a rotating plate that rotates coaxially with the rotating body;
The rotating body drive control device according to claim 1. Drive that controls the rotational speed of a rotating body driven by a reduction gear that decelerates rotation of the motor at a non-integer reduction ratio by controlling a drive signal that determines a voltage value supplied to the motor by a drive control means. Control steps;
A driving step of driving the motor by supplying the voltage value determined by the driving signal by a driving means;
The drive control step includes
A first input step of inputting a first pulse generated at a timing when the motor makes one rotation ;
A second input step of inputting a second pulse generated at a timing when the rotating body makes one rotation ;
The drive signal that calculates the amplitude and phase of the change in rotational speed of the rotating body caused by the eccentricity of the motor based on the input second pulse, and suppresses the change based on the calculated amplitude and phase. A correction value calculating step for calculating a correction value of
The time difference between the time when the first pulse is input and the time when the second pulse is input is calculated, and the relationship between the rotation angle of the motor and the rotation angle of the rotating body is specified based on the calculated time difference. Specific steps,
Judgment whether or not the first relationship that is the relationship specified when the correction value is calculated matches the second relationship that is the relationship that is specified at an arbitrary timing after the correction value is calculated Steps,
An output step of outputting the drive signal corrected with the correction value at a timing at which the second relationship determined to match the first relationship is specified;
A rotating body drive control method comprising: The specifying step determines which reference time difference the calculated time difference corresponds to among the reference time differences that are the time differences determined in advance corresponding to the reduction ratio, and corresponds to each of the reference time differences. Identifying the relationship corresponding to the reference time difference determined to correspond to the calculated time difference from the relationship to
The rotating body drive control method according to claim 11. In the specifying step, for the calculated first time difference, the magnitude relationship between the first time difference and the second time difference calculated before the first time difference is the same as the magnitude relation with respect to the other reference time differences. Identifying the relationship corresponding to the time difference;
The rotating body drive control method according to claim 12. The specifying step is the reference time difference corresponding to the calculated time difference, wherein the difference between the absolute value of the calculated time difference and the absolute value of the reference time difference is smaller than a predetermined second threshold. Identifying the relationship corresponding to the reference time difference determined to correspond,
The rotating body drive control method according to claim 12. The specifying step calculates the reference time difference in which the difference between the ratio of the calculated time difference with respect to the pulse period of the first pulse and the ratio of the reference time difference with respect to the pulse period is smaller than a predetermined third threshold value. Determining the reference time difference corresponding to the time difference and identifying the relationship corresponding to the reference time difference determined to correspond;
The rotating body drive control method according to claim 12. The determining step determines whether or not the first relationship identified by the information stored in the storage unit storing information for identifying the identified first relationship matches the second relationship. thing,
The rotating body drive control method according to claim 11. In the first input step, the first pulse which is an FG (Frequency Generator) signal having a frequency corresponding to the number of rotations of the motor is input.
The rotating body drive control method according to claim 11. In the first input step, the first pulse output from a rotary encoder that rotates coaxially with the motor is input.
The rotating body drive control method according to claim 11. In the first input step, the first pulse output from a Hall element that detects a magnetic pole position of a magnet constituting the motor is input.
The rotating body drive control method according to claim 11. In the second input step, the second pulse output from a sensor that detects a rotation angle of a rotating plate that rotates coaxially with the rotating body is input.
The rotating body drive control method according to claim 11.   A program that causes a computer to execute the rotating body drive control method according to any one of claims 11 to 20. An image forming apparatus for forming a toner image on a transfer target,
A conveying means which is rotatably held and conveys the transfer object;
An image carrier for carrying a toner image formed to be held rotatably;
Charging means for uniformly charging the surface of the image carrier;
A latent image forming means for forming a latent image on the surface of the image carrier that is uniformly charged by the charging means;
Developing means for visualizing the latent image formed by the latent image forming means;
A transfer unit that is rotatably held and transfers the toner image visualized by the developing unit to the transfer target;
A rotating body drive control device that controls driving of a motor that rotates at least one of the transport means, the image carrier, the intermediate transfer body, and the transfer means,
The rotating body drive control device includes:
Drive control means for controlling the rotational speed of a rotating body driven by a reduction gear that reduces the rotation of the motor at a non-integer reduction ratio by controlling a drive signal for determining a voltage value supplied to the motor;
Drive means for driving the motor by supplying the voltage value determined by the drive signal;
The drive control means includes
First input means for inputting a first pulse generated at a timing when the motor makes one rotation ;
Second input means for inputting a second pulse generated at a timing when the rotating body makes one rotation ;
The drive signal that calculates the amplitude and phase of the change in rotational speed of the rotating body caused by the eccentricity of the motor based on the input second pulse, and suppresses the change based on the calculated amplitude and phase. Correction value calculating means for calculating the correction value of
The time difference between the time when the first pulse is input and the time when the second pulse is input is calculated, and the relationship between the rotation angle of the motor and the rotation angle of the rotating body is specified based on the calculated time difference. Specific means,
Judgment whether or not the first relationship that is the relationship specified when the correction value is calculated matches the second relationship that is the relationship that is specified at an arbitrary timing after the correction value is calculated Means,
Output means for outputting the drive signal corrected with the correction value at a timing at which the second relationship determined to match the first relationship is specified;
An image forming apparatus comprising:

Images