JP2019154236A - Controller, drive unit, and image forming apparatus - Google Patents

Abstract

To perform position hold control without providing a detector on an output shaft of a brushless DC motor or an object to be driven.SOLUTION: A driver circuit 220 comprises: a motor drive circuit 221 that supplies power to a motor 210 while switching its polarity according a magnetic pole phase signal output from the motor 210; and a rotation position detection circuit 222 that converts the magnetic pole phase signal and outputs a rotation position detection signal representing an amount of rotation and a direction of rotation of an output shaft of the motor 210 and having a higher resolution than that of the magnetic pole phase signal.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a control device, a driving device, and an image forming apparatus.

  Conventionally, in image forming apparatuses such as copying machines, facsimiles, and printers, stepping motors capable of position / speed / hold control by pulse control have been used as driving force sources in many parts.

  Stepping motors have the advantage that position, speed, and hold control is possible by pulse control, but it is necessary to output and use more torque than necessary in consideration of step-out due to load fluctuations and changes over time. The energy efficiency is poor, and a high output motor having an actual load or more is required, which inevitably results in a large and heavy motor.

  On the other hand, a brushless DC motor has an advantage of high efficiency because a current corresponding to a load flows. However, the motor alone has a disadvantage that position / hold control like a stepping motor cannot be performed.

  Therefore, a method for performing rotational position control by providing a rotary encoder on the output shaft of the brushless DC motor (see Patent Document 1), or a method for performing rotational position control by providing a linear encoder on a driven body driven by the brushless DC motor. (See Patent Document 2) and the like.

  However, when a detection device such as an encoder or resolver is provided on the output shaft or driven body of a brushless DC motor, a malfunction occurs due to dust or the like biting into the drive unit of the detection device, and a malfunction due to the thermal effect of the detection device Or, problems such as an increase in manufacturing cost due to an increase in the number of parts occur.

  The present invention has been made in view of the above, and provides a driving device and an image forming apparatus capable of performing position / hold control without providing a detection device on the output shaft or driven body of a brushless DC motor. The purpose is to do.

  In order to solve the above-described problems and achieve the object, a control device of the present invention includes a motor drive unit that supplies power to the motor in accordance with a magnetic pole phase signal output from the motor, and converts the magnetic pole phase signal. And a rotational position detector that represents a rotational amount and a rotational direction of the output shaft of the motor and outputs a rotational position detection signal having a high resolution with respect to the magnetic pole phase signal.

  According to the present invention, it is possible to perform position / hold control without providing a detection device on the output shaft or driven body of the brushless DC motor.

FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus according to the present embodiment. FIG. 2 is a partially enlarged view in the vicinity of the process cartridge. FIG. 3 is a diagram showing a schematic configuration of a document conveying device used in the image forming apparatus. FIG. 4 is a block diagram illustrating a schematic configuration of the driving apparatus according to the first embodiment. FIG. 5 is a plan view of the motor as viewed from the side that is not the drive shaft. FIG. 6 is a perspective view of the motor as viewed from the side other than the drive shaft. FIG. 7 is a block diagram illustrating a schematic configuration of the driving apparatus according to the second embodiment. FIG. 8 is a circuit diagram showing a schematic configuration of a rotational position detection circuit based on a slice method. FIG. 9 is a timing chart of each signal for explaining a selection method of the selection signal. FIG. 10 is a diagram illustrating determination logic used in the second phase detection circuit. FIG. 11 is a diagram showing selection conditions used in the signal selection circuit. FIG. 12 is a timing chart of each signal showing the operation of the third phase detection circuit. FIG. 13 is a circuit diagram showing a schematic configuration of a rotational position detection circuit by a vector method. FIG. 14 is a timing chart of the angle search sequence. FIG. 15 is a diagram illustrating an angle search sequence operation (count n = 1). FIG. 16 is a diagram illustrating an operation of the angle search sequence (count n = 2). FIG. 17 is a diagram illustrating the operation of the angle search sequence (count n = 3). FIG. 18 is a diagram illustrating an angle search sequence operation (count n = 4). FIG. 19 is a diagram illustrating the generation logic of the 2-channel encoder equivalent signal.

  Hereinafter, embodiments of a control device, a drive device, and an image forming apparatus will be described in detail with reference to the accompanying drawings. In the following, the embodiment will be described assuming that the image forming apparatus is an image forming apparatus such as a copying machine, a printer, a scanner apparatus, and a facsimile apparatus. However, at least two of the copy function, printer function, scanner function, and facsimile function are described. It is also possible to apply the present invention to a multifunction machine having one function.

[Image forming apparatus]
FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus 100 according to the present embodiment. As shown in FIG. 1, the image forming apparatus 100 generates toner images of yellow, magenta, cyan, and black (hereinafter referred to as “Y”, “M”, “C”, and “K”, respectively). 4 process cartridges 6Y, 6M, 6C, and 6K are provided.

  These process cartridges 6Y, 6M, 6C, and 6K use Y toner, M toner, C toner, and K toner of different colors as image forming agents, but the other configurations are the same. Each of the process cartridges 6Y, 6M, 6C, and 6K can be attached to and detached from the main body of the image forming apparatus 100, so that consumable parts can be replaced at a time, and are replaced when the end of the service life is reached.

  Since the process cartridges 6Y, 6M, 6C, and 6K have the same configuration, the schematic configuration of the image forming apparatus 100 will be described by taking the process cartridge 6Y for generating a Y toner image as an example. FIG. 2 is a partially enlarged view in the vicinity of the process cartridge 6Y shown in FIG. In the following, reference is made to FIG. 2 together with reference to FIG.

  As shown in FIG. 2, the process cartridge 6Y includes a photosensitive drum 1Y as a latent image carrier, a drum cleaning device 2Y, a charge eliminating device (not shown), a charging device 4Y, a developing device 5Y, and the like.

  The charging device 4Y is a device that uniformly charges the surface of the photosensitive drum 1Y. The photosensitive drum 1Y is rotated clockwise in the drawing by the drum rotating mechanism, and the photosensitive drum 1Y rotates, whereby the charging device 4Y uniformly charges the surface of the photosensitive drum 1Y.

  The uniformly charged surface of the photosensitive drum 1Y is exposed and scanned by the laser beam L to carry an electrostatic latent image for Y. The electrostatic latent image on the surface of the photoreceptor drum 1Y is developed into a Y toner image by the developing device 5Y using Y toner. The Y toner image on the surface of the photosensitive drum 1Y is intermediately transferred onto the intermediate transfer belt 8. This process is called an intermediate transfer process.

  The drum cleaning device 2Y is a device that removes toner remaining on the surface of the photosensitive drum 1Y after the intermediate transfer process. The static eliminator is a device that neutralizes residual charges on the photoreceptor drum 1Y after cleaning. By this charge removal, the surface of the photosensitive drum 1Y is initialized and prepared for the next image formation.

  In the other process cartridges 6M, 6C, and 6K, M toner images, C toner images, and K toner images are formed on the photosensitive drums 1M, 1C, and 1K, respectively, on the intermediate transfer belt 8. Intermediate transfer.

  As shown in FIG. 1, an exposure device 7 is disposed below each process cartridge 6Y, 6M, 6C, 6K in the drawing.

  The exposure device 7 is a device for forming an electrostatic latent image on the surface of each of the photosensitive drums 1Y, 1M, 1C, and 1K described above. The exposure device 7 irradiates the respective photosensitive drums 1Y, 1M, 1C, and 1K in the process cartridges 6Y, 6M, 6C, and 6K with a laser beam L that is emitted based on information on an image to be formed. The surfaces of the drums 1Y, 1M, 1C, and 1K are exposed. By this exposure, Y electrostatic latent images, M electrostatic latent images, C electrostatic latent images, and K electrostatic latent images are formed on the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K, respectively.

  The exposure apparatus 7 irradiates the photosensitive drum with a desired electrostatic potential by irradiating the photosensitive drum with a plurality of optical lenses and mirrors while scanning the laser light L emitted from the light source with a polygon mirror rotated by a motor. The latent images are formed on the surfaces of the photosensitive drums 1Y, 1M, 1C, and 1K, respectively.

  As shown in FIG. 1, a sheet feeding means is disposed on the lower side of the exposure apparatus 7 in the drawing. The paper supply means includes a paper storage cassette 26, a paper supply roller 27 incorporated in the paper storage cassette 26, a registration roller pair 28, and the like.

  The paper storage cassette 26 stores a plurality of sheets 99 as recording materials, and a paper feed roller 27 is in contact with the uppermost sheet 99. When the paper feeding roller 27 is rotated counterclockwise in the drawing by the driving mechanism, the uppermost paper 99 is fed toward the rollers of the registration roller pair 28.

  The registration roller pair 28 rotationally drives both rollers so as to sandwich the paper 99, but temporarily stops rotating immediately after sandwiching. Then, the sheet 99 is sent out toward a secondary transfer nip described later at an appropriate timing.

  On the other hand, as shown in FIG. 1, an intermediate transfer unit 15 is disposed above the process cartridges 6Y, 6M, 6C, and 6K. Has been.

  The intermediate transfer unit 15 includes a belt cleaning device 10 in addition to the intermediate transfer belt 8. Also provided are four primary transfer bias rollers 9Y, 9M, 9C, 9K, a secondary transfer backup roller 12, a cleaning backup roller 13, a tension roller 14, and the like.

  The intermediate transfer belt 8 is endlessly moved in the counterclockwise direction in the figure by the rotational drive of at least one roller while being stretched around the seven rollers. The primary transfer bias rollers 9Y, 9M, 9C, and 9K respectively sandwich the intermediate transfer belt 8 with the photosensitive drums 1Y, 1M, 1C, and 1K to form primary transfer nips. In other words, the primary transfer bias rollers 9Y, 9M, 9C, and 9K are arranged on the opposite side of the photosensitive drums 1Y, 1M, 1C, and 1K via the intermediate transfer belt 8, and the toner and the intermediate transfer belt 8 are in contact with toner. Applies a transfer bias of reverse polarity (for example, positive polarity).

  All the rollers except the primary transfer bias rollers 9Y, 9M, 9C, and 9K are electrically grounded. The intermediate transfer belt 8 sequentially passes through the primary transfer nips for Y, M, C, and K along with the endless movement thereof, and the Y toner images on the respective photosensitive drums 1Y, 1M, 1C, and 1K. The M toner image, the C toner image, and the K toner image are superimposed and primarily transferred. As a result, a four-color superimposed toner image (hereinafter referred to as “four-color toner image”) is formed on the intermediate transfer belt 8.

  Further, the secondary transfer backup roller 12 sandwiches the intermediate transfer belt 8 between the secondary transfer roller 19 and forms a secondary transfer nip. The four-color toner image formed on the intermediate transfer belt 8 is transferred to the paper 99 at the secondary transfer nip. Then, combined with the white color of the paper 99, a full color toner image is obtained.

  Untransferred toner that has not been transferred to the paper 99 adheres to the intermediate transfer belt 8 after passing through the secondary transfer nip. The transfer residual toner is cleaned by the belt cleaning device 10. In the secondary transfer nip, the sheet 99 is sandwiched between the intermediate transfer belt 8 whose surface moves in the forward direction and the secondary transfer roller 19 and is conveyed in the opposite direction to the registration roller pair 28 side.

  The sheet 99 fed from the secondary transfer nip is affected by heat and pressure when passing between the rollers of the fixing unit 20 as a detachable unit with respect to the image forming apparatus 100 main body. The toner image is fixed. Thereafter, the sheet 99 is discharged out of the image forming apparatus 100 through the rollers of the pair of discharge rollers 29.

  A stack unit 30 is formed on the upper surface of the casing of the main body of the image forming apparatus 100, and the sheets 99 discharged out of the apparatus by the discharge roller pair 29 are sequentially stacked on the stack unit 30.

  As shown in FIG. 1, a bottle support portion 31 is disposed between the intermediate transfer unit 15 and the stack portion 30 located above the intermediate transfer unit 15. To the bottle support portion 31, toner bottles 32Y, 32M, 32C, and 32K are set as agent containers for storing the respective color toners.

  The color toners in the toner bottles 32Y, 32M, 32C, and 32K are appropriately supplied to the developing devices of the process cartridges 6Y, 6M, 6C, and 6K by the toner supply devices. The toner bottles 32Y, 32M, 32C, and 32K are detachable from the main body of the image forming apparatus 100 independently of the process cartridges 6Y, 6M, 6C, and 6K.

  FIG. 3 is a diagram showing a schematic configuration of the document conveying device 101 used in addition to the image forming apparatus 100 described above. The document conveying apparatus 101 is disposed on the upper part of the image forming apparatus 100 shown in FIG. 1, and the image forming apparatus 100 and the document conveying apparatus 101 function as a copier, MFP, or the like. Therefore, the image forming apparatus 100 to which the document conveying apparatus 101 is added is also referred to as the image forming apparatus 100 without distinction.

  A document conveying apparatus 101 shown in FIG. 3 is applied to a read document processing apparatus (hereinafter referred to as ADF) that conveys a document to be read to a fixed reading device unit and reads an image while conveying the document at a predetermined speed. Is.

  The document conveying apparatus 101 includes an original setting unit A for setting a read original bundle, a separation feeding unit B for separating and feeding originals one by one from the set original bundle, and abutting alignment of the fed originals Then, the registration unit C that pulls out and conveys the document after alignment, the turn unit D that turns the conveyed document and conveys the document surface toward the reading side (downward), and displays the surface image of the document below the contact glass. A first reading / conveying unit E for performing reading, a second reading / conveying unit F for reading a back side image of a document after reading, a paper discharge unit G for discharging a document whose front and back have been read out of the machine, A stack portion H for stacking and holding documents is provided. The document conveying apparatus 101 includes a pickup motor, a sheet feeding motor, a reading motor, a sheet discharging motor, a bottom plate raising motor, and the like as a driving source for driving the conveying operation.

  The document table 42 includes a movable document table 43, and a sheet 99 to be read is set. The sheet 99 is set on the document table 42 with the document surface facing upward. The document table 42 includes a side guide, and the width direction of the sheet 99 is positioned in a direction orthogonal to the transport direction. The set paper 99 is detected by the set filler 44 and the set sensor 45 and transmitted to the main body control unit.

  Document length detection sensors 70 and 71 (a reflection type sensor or an actuator type sensor that can be detected even on 99 sheets of paper) are arranged on the document table 42. Document length detection sensors 70 and 71 determine the length of the document in the conveyance direction. At this time, the document length detection sensors 70 and 71 are arranged so as to be able to determine at least whether the document size is vertical or horizontal.

  The movable document table 43 can be moved up and down in the directions of arrows a and b by a bottom plate raising motor. When the set filler 44 and the set sensor 45 detect that the original is set on the movable original table 43, the bottom plate raising motor is rotated forward so that the uppermost surface of the original bundle comes into contact with the pickup roller 47. Raise. In FIG. 3, the ascending state is indicated by a solid line.

  The pickup roller 47 is moved in the directions of arrows c and d by a cam mechanism by a pickup motor, and the movable document table 43 is raised and pushed by the upper surface of the document on the movable document table 43 to rise in the c direction, and the table rise detection sensor 48. The upper limit can be detected.

  The paper feeding belt 49 is driven in the paper feeding direction by the normal rotation of the paper feeding motor, and the reverse roller 50 is driven to rotate in the reverse direction to the paper feeding by the normal rotation of the paper feeding motor. In this configuration, only the uppermost document can be fed.

  The reverse roller 50 is in contact with the paper feed belt 49 at a predetermined pressure, and when two or more originals enter between the paper feed belt 49 and the reverse roller 50, the reverse roller 50 rotates in the clockwise direction, which is the original driving direction, and is redundant. This function pushes back the original and prevents double feeding of the original.

  The original separated by the action of the paper feeding belt 49 and the reverse roller 50 is further fed by the paper feeding belt 49, and the leading edge is detected by the abutting sensor 51 and further abuts against the pull-out roller 52 stopped. Thereafter, the sheet feeding motor is sent by a predetermined distance from the detection of the abutting sensor 51, and as a result, the paper feeding motor is stopped while being pressed against the pull-out roller 52 with a predetermined amount of bending. As a result, the driving of the paper feed belt 49 is stopped.

  At this time, the pickup motor 47 is retracted from the upper surface of the document by rotating the pickup motor, and the document is fed only by the conveying force of the paper feed belt 49, so that the leading edge of the document enters the nip of the upper and lower rollers of the pull-out roller 52. Then, tip alignment (skew correction) is performed.

  The pull-out roller 52 has the skew correction function and conveys the skew-corrected document after separation to the intermediate roller 54, and is driven by the reverse rotation of the paper feed motor. Note that the pull-out roller 52 and the intermediate roller 54 are driven at the time of reverse rotation of the paper feed motor, but the pickup roller 47 and the paper feed belt 49 are not driven.

  A plurality of document width sensors 53 are arranged in the depth direction and detect the size in the width direction perpendicular to the transport direction of the document transported by the pull-out roller 52. The length of the document in the conveyance direction is detected by a motor pulse by reading the leading edge and the trailing edge of the document with an abutment sensor 51.

  When the document is transported from the resist section C to the turn section D by driving the pull-out roller 52 and the intermediate roller 54, the transport speed at the resist section C is set to be higher than the transport speed at the first reading transport section E. Thus, the processing time for sending the document to the reading unit is shortened.

  When the leading edge of the document is detected by the reading inlet sensor 55, the reading motor is driven forward to drive the reading inlet roller 56, the reading outlet roller 63, and the CIS outlet roller 67.

When the leading edge of the document is detected by the registration sensor 57, the document sensor decelerates over a predetermined conveyance distance, temporarily stops before the reading position 60 where the first reading unit (not shown) is arranged, and the main body control unit receives I. A stop signal is transmitted via / F.

  Subsequently, when a reading start signal is received from the main body control unit, the stopped document is transported at an increased speed so as to rise to a predetermined transport speed until the leading end of the document reaches the reading position.

  At the timing when the leading edge of the document detected by the pulse count of the reading motor reaches the reading unit, a gate signal indicating the effective image area in the sub-scanning direction on the first surface is sent to the main body control unit, and the first reading unit is moved to the trailing edge of the document Sent until is removed.

  In the case of reading a single-sided document, the document that has passed through the first reading and conveying unit E is conveyed to the paper discharge unit G through the second reading unit 65. At this time, when the leading edge of the document is detected by the paper discharge sensor 64, the paper discharge motor is driven to rotate forward to rotate the paper discharge roller 68 counterclockwise.

  Further, the discharge motor drive speed is reduced immediately before the trailing edge of the document comes out of the nip between the upper and lower roller pairs of the discharge roller 68 by the discharge motor pulse count from the detection of the leading edge of the document by the discharge sensor 64 to discharge the sheet. Control is performed so that the document discharged onto the tray 69 does not jump out.

  The surface of the second reading unit 65 is subjected to a coating process and a coating member is disposed in order to prevent vertical streaks due to transfer of glue on the original onto the reading line.

  This coating member is formed by applying a coating material having a dirt decomposition function or a hydrophilic coating material to the reading surface of the second reading unit 65. These coating materials can use a well-known thing.

[Drive Device of First Embodiment]
FIG. 4 is a block diagram illustrating a schematic configuration of the driving device 200-1 according to the first embodiment. The drive device 200-1 shown in FIG. 4 can be used, for example, as a drive mechanism that drives the paper feed roller 27 and the like of the image forming apparatus 100 main body shown in FIG. Further, for example, it can be used for a driving mechanism for driving the reading entrance roller 56, the reading exit roller 63, or the CIS exit roller 67 of the document conveying apparatus 101 shown in FIG.

  As shown in FIG. 4, the driving device 200-1 includes a motor 210 that is a driving source, a driver circuit 220 that supplies power to the motor 210, and a control circuit 230-1 that controls the motor 210 via the driver circuit 220. Prepare. However, although the driver circuit 220 and the control circuit 230-1 are shown separately in FIG. 4, for example, as shown in FIGS. 5 and 6, the two circuits are configured on the same substrate. Is preferred. FIG. 5 is a plan view when the motor 210 is viewed from the side that is not the drive shaft (the side opposite to the drive shaft), and FIG. 6 is a perspective view when the motor 210 is viewed from the side that is not the drive shaft. 5 and 6, reference numeral 300 represents a connector, reference numerals 211, 212, and 213 represent Hall elements, and reference numerals 301, 302, and 303 represent FETs that function as switches. Since the input signals of the driver circuit 220 and the control circuit 230-1 are the same, the board can be used effectively by configuring them on the same board. Furthermore, although the driver circuit 220 shown in FIG. 4 is shown in a form that is not mounted on the motor 210, when the driver circuit 220 is mounted on a board on the motor 210, the number of harnesses can be reduced. This leads to cost reduction. In FIG. 4, the control circuit 230-1 drives one motor 210 via one driver 220. However, the control circuit 230-1 drives a plurality of motors 210 via a plurality of drivers 220. May be. In that case, the driver circuit 220 and the control circuit 230-1 may be configured on the same substrate, but are preferably separated. This is because it is desirable that the Hall elements 211, 212, 213 and the driver circuit 220 arranged in the vicinity of the winding of the motor 210 are formed on the same substrate, so that the plurality of driver circuits 220 and the control circuit 230-1 are the same. This is because it cannot be configured on the substrate.

  The motor 210 is a three-phase brushless DC motor. That is, the motor 210 is an electric motor that does not have a commutator and whose direction of the magnetic pole is switched by switching a direct current supplied from the driver circuit 220 by a semiconductor switch.

  Since the motor 210 does not have a commutator, the direction of the magnetic pole must be switched by a separate method. For this purpose, the motor 210 has a mechanism for feeding back a magnetic pole phase signal representing the magnetic pole phase of the motor 210. Since the motor 210 shown in FIG. 4 is a three-phase drive, it includes three Hall elements 211, 212, and 213 to feed back the magnetic pole phase signal. The Hall elements 211, 212, and 213 are elements that detect a magnetic field in the motor 210 by the Hall effect. The magnetic pole phase signals output from the Hall elements 211, 212, and 213 are also called Hall signals.

  The motor 210 shown in FIG. 4 includes Hall elements 211, 212, and 213 for magnetic pole phase signal feedback, but may be a so-called sensorless brushless DC motor that detects a counter electromotive force. . In FIG. 4, the driver circuit 220 and the Hall elements 211, 212, and 213 are illustrated separately, but for example, as shown in FIGS. 5 and 6, they are preferably configured on the same substrate. . The reason is that signal disturbance due to external noise is less likely to occur than connection by harness, and the number of harnesses is reduced, leading to cost reduction. More specifically, in the example of FIGS. 5 and 6, since the connector 300 is connected to the target drive signal generating unit 240 described later, only the target drive signal described later input from the target drive signal generating unit 240 is input. Just do it. Thereby, the number of harnesses can be reduced. Further, as will be described later, the output from the target drive signal generating means 240 is a signal indicating the rotation direction and the number of pulses in the same manner as that output to the conventional stepping motor. Thus, the drive device 200-1 (portion shown in FIGS. 5 and 6) can be replaced.

  The driver circuit 220 includes a motor drive circuit 221 and a rotational position detection circuit 222.

  A motor drive circuit 221 in the driver circuit 220 supplies power to the motor 210 in accordance with the magnetic pole phase signal output from the motor 210. In this example, the motor drive circuit 221 corresponds to a “motor drive unit” in the claims. More specifically, it is as follows. The motor drive circuit 221 is configured as a four-quadrant driver, and a current applied to the motor 210 based on a control signal obtained from the control circuit 230-1 and a hall signal obtained from the hall elements 211, 212, and 213. And control the voltage independently.

  On the other hand, the rotational position detection circuit 222 in the driver circuit 220 converts the magnetic pole phase signal output from the motor 210 to represent the amount and direction of rotation of the output shaft of the motor 210, and has a resolution for the magnetic pole phase signal. A high rotational position detection signal is output. In this example, the rotational position detection circuit 222 corresponds to a “rotational position detector” in the claims. More specifically, it is as follows. The rotational position detection circuit 222 generates a rotational position signal that represents the rotational position of the output shaft of the motor 210 from the Hall signals obtained from the Hall elements 211, 212, and 213. This rotational position signal is a 2-channel encoder equivalent signal when a rotary encoder is provided on the output shaft of the motor 210, and corresponds to the “rotational position detection signal” in the claims. As a method for generating the 2-channel encoder equivalent signal by the rotational position detection circuit 222, for example, there are a slice method and a vector method, and these methods will be described in detail later.

  The control circuit 230-1 transmits a control signal to the motor drive circuit 221 based on the rotation position signal output from the rotation position detection circuit 222 and the target drive signal input from the host device. In this example, the control circuit 230-1 corresponds to a “control unit” in the claims. In this example, the combination of the driver circuit 220 and the control circuit 230-1 can be considered to correspond to the “control device” in the claims. It can also be considered that only the driver circuit 220 corresponds to the “control device” in the claims. Hereinafter, specific contents of the control circuit 230-1 will be described. The control circuit 230-1 compares the target drive signal from the external target drive signal generation means 240 with the rotational position signal from the rotational position detection circuit 222, and controls the DC power that the driver circuit 220 should supply to the motor 210. To do. In this example, the target drive signal generation means 240 corresponds to the “higher level device” in the claims.

  The control circuit 230-1 includes a target position / speed calculation circuit 231, a position / speed tracking controller 232, and a motor position / speed calculation circuit 233.

  The target position / velocity calculation circuit 231 acquires a rotation direction signal and a signal of the number of movement pulses as a target drive signal from an external target drive signal generation unit 240. Then, the target position / speed calculation circuit 231 derives the target position and the target speed of the motor 210 from the obtained target drive signal and the time signal of the oscillator included in the control circuit 230-1, and obtains the target position and the target speed. This is transmitted to the position / speed tracking controller 232.

  On the other hand, the motor position / speed calculation circuit 233 receives the rotation position signal from the rotation position detection circuit 222 in the driver circuit 220 and acquires the rotation direction and the number of movement pulses of the output shaft of the motor 210. As described above, the rotational position signal is a two-channel encoder equivalent signal when a rotary encoder is provided on the output shaft of the motor 210, and the output changes according to the rotation angle of the motor output shaft. It is a 2-channel signal of 90 °). Therefore, the motor position / speed calculation circuit 233 can acquire the rotation direction and the number of movement pulses of the output shaft of the motor 210 using this phase difference.

  Further, the motor position / speed calculation circuit 233 derives the rotational position and rotational speed of the motor 210 from the rotational direction and number of movement pulses of the output shaft of the motor 210 and the time signal of the oscillator, and determines the rotational position and rotational speed as positions. Transmit to the speed tracking controller 232.

  The position / speed tracking controller 232 adjusts the target position and speed acquired from the target position / speed calculation circuit 231 and the rotational position and speed acquired from the motor position / speed calculation circuit 233 as necessary. The motor drive circuit 221 is controlled so as to send signals such as PWM output, rotation direction, start, stop, and brake.

  The motor drive circuit 221 is configured as a four quadrant driver as described above. Therefore, the control circuit 230-1 obtains the target rotation amount ΔXt and target total rotation amount Xt per unit time from the target drive signal, and calculates the motor rotation amount ΔXm and motor total rotation amount Xm per unit time from the rotation position signal. After that, the target total rotation amount Xt and the motor total rotation amount Xm are equal (Xt = Xm), and the target rotation amount ΔXt per unit time and the motor rotation amount ΔXm per unit time are equal (ΔXt = ΔXm). As described above, the rotation of the motor 210 is controlled by changing the control signal to the motor drive circuit 221.

  As described above, the drive device 200-1 of the present embodiment normally detects the rotation position of the output shaft of the motor 210 using the hall signal used for switching the polarity of the electric power that the motor drive circuit 221 supplies to the motor 210. Also used. For this reason, the driving device 200-1 of this embodiment is provided with a rotational position detection circuit that converts the hall signal in the driver circuit 220 and outputs a rotational position signal that represents the rotational amount and rotational direction of the output shaft of the motor 210. ing. With this configuration, the driving device 200-1 of the present embodiment can perform position / hold control without providing a detection device such as an encoder or resolver on the output shaft of the motor 210 or the driven body.

  Further, the rotational position detection signal in the driving device 200-1 of the present embodiment is a two-channel encoder equivalent signal when a rotary encoder is provided on the output shaft of the motor 210, and is very compatible with the conventional driving device. In particular, the driving device 200-1 according to the present embodiment can be replaced with a stepping motor that has been conventionally used for a driving mechanism in the image forming apparatus 100 without changing other configurations. Is possible. The 2-channel encoder equivalent signal is generally two rectangular wave signals having a phase difference of 90 ° in electrical angle, but may be a waveform signal other than a rectangular wave, such as a sine wave or a triangular wave.

[Drive Device of Second Embodiment]
FIG. 7 is a block diagram illustrating a schematic configuration of the driving device 200-2 of the second embodiment. The drive device 200 shown in FIG. 7 can be used, for example, as a drive mechanism for driving the reading entrance roller 56, the reading exit roller 63, or the CIS exit roller 67 of the document conveying device 101 in FIG. Further, for example, it can be used for a drive mechanism that drives the paper feed roller 27 and the like of the main body of the image forming apparatus 100 in FIG. Since the driving device 200-2 of the second embodiment has many common configurations with the driving device 200-1 of the first embodiment, the following description is omitted as appropriate.

  The motor 210 is a brushless DC motor. That is, the motor 210 is an electric motor that does not have a commutator and whose direction of the magnetic pole is switched by switching a direct current supplied from the driver circuit 220 by a semiconductor switch.

  The driver circuit 220 includes a motor drive circuit 221 and a rotational position detection circuit 222.

  The motor driving circuit 221 in the driver circuit 220 is configured as a four-quadrant driver, and based on the control signal obtained from the control circuit 230-2 and the Hall signal obtained from the Hall elements 211, 212, and 213, The current and voltage applied to the motor 210 are controlled independently.

  On the other hand, the rotational position detection circuit 222 in the driver circuit 220 generates a rotational position signal representing the rotational position of the output shaft of the motor 210 from the Hall signals obtained from the Hall elements 211, 212, and 213. This rotational position signal is a 2-channel encoder equivalent signal when a rotary encoder is provided on the output shaft of the motor 210. As a method for generating the 2-channel encoder equivalent signal by the rotational position detection circuit 222, for example, there are a slice method and a vector method, and these methods will be described in detail later.

  The control circuit 230-2 compares the target drive signal from the external target drive signal generation means 240 with the rotational position signal from the rotational position detection circuit 222, and controls the DC power that the driver circuit should supply to the motor 210. .

  Specifically, the control circuit 230-2 includes a target position calculation circuit 234, a position tracking controller 235, and a motor position calculation circuit 236.

  The target position calculation circuit 234 in the control circuit 230-2 acquires a rotation direction signal and a signal of the number of movement pulses as the target drive signal from the external target drive signal generation means 240. Then, the target position calculation circuit 234 derives the target position of the motor 210 from the obtained target drive signal and the time signal of the oscillator, and transmits the target position to the position tracking controller 235.

  On the other hand, the motor position calculation circuit 236 in the control circuit 230-2 receives the rotation position signal from the rotation position detection circuit 222 in the driver circuit 220, and acquires the rotation direction and the number of movement pulses of the output shaft of the motor 210. Further, the motor position calculation circuit 236 derives the rotation position of the motor 210 from the rotation direction and the number of movement pulses of the output shaft of the motor 210 and the time signal of the oscillator, and transmits the rotation position to the position tracking controller 235.

  The position follow-up controller 235 adjusts the PWM output, rotation direction, start, stop, and brake as necessary so that the target position acquired from the target position calculation circuit 234 matches the rotation position acquired from the motor position calculation circuit 236. The motor drive circuit 221 is controlled to send such a signal.

  The motor drive circuit 221 is configured as a four quadrant driver as described above. Therefore, the control circuit 230-2 obtains the target total rotation amount Xt from the target drive signal and the motor total rotation amount Xm from the rotation position signal, and then the target total rotation amount Xt and the motor total rotation amount Xm become equal. As described above, the rotation of the motor 210 is controlled by changing the control signal to the motor drive circuit 221.

  As described above, the drive device 200-2 of the present embodiment normally uses the Hall signal used for switching the polarity of the power supplied to the motor 210 by the motor drive circuit 221 to detect the rotational position of the output shaft of the motor 210. Also used. For this reason, the driving device 200-2 of the present embodiment is provided with a rotational position detection circuit that converts a hall signal into the driver circuit 220 and outputs a rotational position signal that represents the rotational amount and rotational direction of the output shaft of the motor 210. ing. With this configuration, the driving device 200-2 of the present embodiment can perform position / hold control without providing a detection device such as an encoder or resolver on the output shaft of the motor 210 or the driven body.

  Further, the rotational position detection signal in the driving device 200-2 of the present embodiment is a 2-channel encoder equivalent signal when a rotary encoder is provided on the output shaft of the motor 210, and is very compatible with the conventional driving device. In particular, the driving device 200-2 according to the present embodiment can be replaced with a stepping motor that has been conventionally used for a driving mechanism in the image forming apparatus 100 without changing other configurations. Is possible. The 2-channel encoder equivalent signal is generally two rectangular wave signals having a phase difference of 90 ° in electrical angle, but may be a waveform signal other than a rectangular wave, such as a sine wave or a triangular wave.

  Hereinafter, a configuration example of the rotational position detection circuit 222 that is a common configuration in the driving device 200-1 of the first embodiment and the driving device 200-2 of the second embodiment described above will be described.

[Slicing method]
FIG. 8 is a circuit diagram showing a schematic configuration of the rotational position detection circuit 222 by the slice method. As shown in FIG. 8, the rotational position detection circuit 222 includes a Hall signal from the U-phase Hall element 211, a Hall signal from the V-phase Hall element 212, and a Hall signal from the W-phase Hall element 213. Is input, and a 2-channel encoder equivalent signal is output.

  Each Hall signal is a differential signal, the differential signal from the U-phase Hall element 211 is U1, U1-, the differential signal from the V-phase Hall element 212 is V1, V1-, and the W-phase Hall The differential signals from the element 213 are W1 and W1-. Further, the 2-channel encoder equivalent signals output from the rotational position detection circuit 222 are assumed to be ENC1 and ENC2.

  As illustrated in FIG. 8, the rotational position detection circuit 222 is combined with the first phase detection circuit 310, the second phase detection circuit 320, the third phase detection circuit 330, the phase division circuit 340, and the signal selection circuit 350. Circuit 360.

  The differential signals (U1, U1-; V1, V1-; W1, W1-) from the Hall elements 211, 212, and 213 are respectively selected from the first phase detection circuit 310 and the second phase detection circuit 320. Input to the circuit 350.

  The first phase detection circuit 310 includes three comparators 311, 312, and 313. Each comparator 311, 312, 313 compares the amplitude of each input differential signal with a predetermined reference level Ref to compare phase signals U 2, V 2 having a high (Hi) level or a low (Low) level. W2 is generated and output to the synthesis circuit 360. Here, the comparison phase signals U2, V2, and W2 from the first phase detection circuit 310 become the first phase information signal phA having a predetermined phase. The determination method performed by the first phase detection circuit 310 will be described in detail below with reference to FIG.

  The second phase detection circuit 320 includes three comparators 321, 322, and 323. Each comparator 321, 322, 323 generates binary comparison phase signals U 3, V 3, W 3 and outputs them to the phase division circuit 340 and the synthesis circuit 360. Here, the comparison phase signals U3, V3, and W3 from the second phase detection circuit 320 become the second phase information signal phB having a predetermined phase, respectively. The determination method performed by the second phase detection circuit 320 will be described in detail below with reference to FIG.

  The phase division circuit 340 generates a signal selection command based on the comparison phase signals U 2, V 2, W 2, U 3, V 3, W 3 and outputs the signal selection command to the signal selection circuit 350. Here, differential signals U 1, U 1-, V 1, V 1-, W 1, W 1-are input to the signal selection circuit 350, and the signal selection circuit 350 is based on a signal selection command from the phase division circuit 340. As described below in detail with reference to FIG. 9, an appropriate signal is selected, and this is output as a selection signal X to the third phase detection circuit 330. The selection method performed by the signal selection circuit 350 will be described in detail below with reference to FIG.

  FIG. 9 is a timing chart of each signal for explaining a selection method of the selection signal X. Here, since the differential signals (U1, U1-; V1, V1-; W1, W1-) are the differential signals from the Hall elements 211, 212, 213, the respective phase differences are 120 °. .

  First, as shown in FIG. 9, in the first phase detection circuit 310, (1) a comparison phase signal U2 is obtained as a result of the magnitude comparison between the sensor signal U1 and the sensor signal U1-, and (2) the sensor A comparison phase signal V2 is obtained as a result of the magnitude comparison between the signal V1 and the sensor signal V1-, and (3) a comparison phase signal W2 is obtained as a result of the magnitude comparison between the sensor signal W1 and the sensor signal W1-.

  On the other hand, in the second phase detection circuit 320, the comparison phase signals U3, V3, and W3 are obtained by comparing the differential signals U1, V1, and W1 according to the determination logic shown in FIG. Note that the comparison phase signals U3, V3, and W3 can be obtained by comparing them similarly based on the differential signals U1-, V1-, and W1-.

  The signal selection circuit 350 applies the differential signals (U1, U1-; V1, V1-; W1) by applying the comparison phase signals U2, V2, W2, U3, V3, W3 to the selection conditions shown in FIG. , W1-), one signal is selected and output as a selection signal X.

  As described above, the selection signal X selected by the signal selection circuit 350 is a signal having a division phase of 30 degrees and continuous at the division section boundary. In the sine wave, the phase range of 150 to 180 degrees and 0 to 30 degrees has very high linearity, which is very advantageous for detecting the phase level in the third phase detection circuit 330 in the subsequent stage. .

  The third phase detection circuit 330 includes N-1 voltage sources 332-1 to 332- (N-1) and N phase detectors 331-1 to 331-N, where N is an integer greater than or equal to 2. It is configured with. The third phase detection circuit 330 uses the selection signal X input from the signal selection circuit 350 to generate a plurality of threshold values generated by the N−1 voltage sources 332-1 to 332- (N−1). Compared with the value level, phase information signals ph (1) to ph (4) are output to the synthesis circuit 360. These phase information signals ph (1) to ph (4) are phase information that can be used to know that the motor 210 has rotated a predetermined angle when the selection signal X reaches a predetermined threshold level. Phase information signal phC.

  The synthesis circuit 360 synthesizes the first phase information signal phA, the second phase information signal phB, and the third phase information signal phC, and outputs a 2-channel encoder equivalent signal.

  Hereinafter, the above-described signal synthesis and synthesis will be described from the viewpoint of the phase of each signal. FIG. 12 is a timing chart of each signal showing the operation of the third phase detection circuit 330. FIG. 12 shows the selection signal X output from the signal selection circuit 350 and the comparison phase signals U2, V2, W2, U3, V3, W3 output from the first phase detection circuit 310 and the second phase detection circuit 320. And the phase information signals ph (1) to ph (4) output from the third phase detection circuit 330 are described side by side.

  As described above, the comparison phase signals U2, V2, and W2 are the first phase information signal phA, the comparison phase signals U3, V3, and W3 are the second phase information signal phB, and the phase information signal ph (1) to ph (4) are the third phase information signal phC. In the above example, threshold levels LV (1) to LV (4) that divide the 30 ° electrical angle section into five equal parts are used.

  As can be seen from FIG. 12, the synthesis circuit 360 synthesizes the phase information signals ph (1) and ph (3) and the comparison phase signals U3, V3, and W3 to make the synthesized signal ENC1, and the phase information signal ph (2 ), Ph (4) and comparison phase signals U2, V2, and W2 are combined into ENC1, and ENC1 and ENC2 are 2-channel encoder equivalent signals.

  As described above, according to the rotational position detection circuit 222 based on the slice method, a 2-channel encoder equivalent signal can be obtained by providing the rotational position detection circuit 222 in the driver circuit 220 without providing a rotary encoder on the output shaft of the motor 210. Obtainable.

  The above-described rotation position detection circuit 222 using the slice method is an example of a rotation position detection circuit using the slice method. In addition to the configuration described above, a phase section with high linearity is selected and connected from the Hall signals (U1, U1-; V1, V1-; W1, W1-) from the Hall elements 211, 212, and 213. A signal selection circuit 350 that outputs the selection signal X, a phase detection circuit that detects the phase information of the Hall signal by comparing the selection signal with a predetermined threshold, and a two-channel encoder equivalent signal ENC1, based on the phase information A rotational position detection circuit 222 including a synthesis circuit that synthesizes ENC2 can be used as appropriate.

[Vector method]
FIG. 13 is a circuit diagram showing a schematic configuration of the rotational position detection circuit 222 by the vector method. As shown in FIG. 13, the rotational position detection circuit 222 receives a Hall signal from the U-phase Hall element 211 and a Hall signal from the V-phase Hall element 212 and outputs a 2-channel encoder equivalent signal. Circuit.

  Each Hall signal is a differential signal. The differential signal from the U-phase Hall element 211 is U + and U−, and the differential signal from the V-phase Hall element 212 is V + and V−. Further, the 2-channel encoder equivalent signals output from the rotational position detection circuit 222 are assumed to be ENC1 and ENC2.

  The rotational position detection circuit 222 according to the vector system of the present embodiment receives the differential signals U + and U− from the U-phase Hall element 211 and the differential signals V + and V− from the V-phase Hall element 212. Although used, an embodiment using differential signals W + and W− from the W-phase Hall element 213 can also be used. Further, in the rotational position detection circuit 222 by the vector method of the present embodiment, it is possible to select and implement any two magnetic pole phases among the U phase, the V phase, and the W phase.

  As shown in FIG. 13, the rotational position detection circuit 222 includes a differential amplifier 410, a vector generation circuit 420, a vector rotation circuit 430, an angle search control circuit 440, and a two-phase pulse generation circuit 450.

  The differential amplifier 410 converts the differential signals U + and U− from the U-phase hall element 211 and the differential signals V + and V− from the V-phase hall element 212 into single ends, and converts them into analog hall signals AU and AV, respectively. Output. Here, the waveforms of the analog hall signals AU and AV are represented by two sine functions having different phases with respect to the rotation angle θ of the output shaft of the motor 210.

  The vector generation circuit 420 includes a subtraction amplifier 421, an addition amplifier 422, and sample hold circuits 423 and 424, and a vector (from the analog hall signals AU and AV input from the differential amplifier 410 based on the X axis component and the Y axis component ( Vx, Vy) is generated.

  The subtraction amplifier 421 subtracts the analog Hall signals AU and AV input from the differential amplifier 410 and multiplies the gain (1 / √3). The sample hold circuit 423 outputs the output of the subtraction amplifier 421 at the timing of the trigger fs. Sample hold and output as X-axis output Vx. Further, the addition amplifier 422 adds the analog Hall signals AU and AV input from the differential amplifier 410, and the sample hold circuit 424 samples and holds the output of the addition amplifier 422 at the timing of the trigger fs and outputs the Y-axis output Vy. Output as.

  The trigger fs is generated by dividing the clock signal clk generated by the oscillator. However, the frequency division ratio when generating the trigger fs is set to be larger than the word length of the detection angle data θd described later so as not to contradict the sequence of the angle search control circuit 440 described later. .

  A simple calculation confirms that the vector (Vx, Vy) created by the vector generation circuit 420 is a trigonometric function with respect to the angle θ, which is a phase difference of 90 ° between the X-axis output Vx and the Y-axis output Vy.

  The vector rotation circuit 430 performs rotation conversion of the vector (Vx, Vy) by converting the trigonometric function related to the angle θ created by the vector generation circuit 420 into the value of detection angle data θd described later, and each of the rotation X-axis components. Vx ′ is output as the rotational Y-axis component Vy ′.

  The vector rotation circuit 430 includes a multiplier 431, an addition amplifier 432, a subtraction amplifier 433, a memory 434, and a DAC (digital-analog converter) 435.

  The memory 434 is a non-volatile memory that divides one cycle into 64, holds sine data sindat and cosine data cosdat whose amplitude is represented by 128 [LSB], and according to the value of the detected angle data θd having a 6-bit word length. Output the data value.

  A DAC (digital-analog converter) 435 changes the data values sindat and cosdat output from the memory 434 to analog values proportional to the values, and outputs them as an analog sine value Asin and an analog cosine value Acos.

  The multiplier 431 is an analog multiplier, and outputs four multiplication results obtained by multiplying the X-axis component Vx and the Y-axis component Vy, the analog sine value Asin, and the analog cosine value Acos in combination.

  The addition amplifier 432 adds predetermined two from the multiplication result of the multiplier 431, and outputs the result as a rotation X-axis component Vx '. At this time, Vx ′ may be multiplied by a gain. The subtraction amplifier 433 subtracts the other from one of two predetermined results from the multiplication result of the multiplier 431, and outputs the result as a rotated Y-axis component Vy '. At this time, Vy ′ may be multiplied by a gain.

  According to the above configuration, the vector rotation circuit 430 performs the calculation of rotating the vector represented by the X-axis component Vx and the Y-axis component Vy clockwise by the value of the detected angle data θd. Note that the analog sine value Asin and the analog cosine value Acos in the present example correspond to a reference sine wave having a plurality of phases in the present embodiment.

  The rotation Y-axis component Vy ′ output from the vector rotation circuit 430 is input to the angle search control circuit 440.

  The angle search control circuit 440 includes a sign determination circuit 441, a sequencer 442, and a successive approximation register (SAR) 443. The angle search control circuit 440 changes the detected angle data θd each time the trigger fs arrives, and the rotation Y-axis component Vy ′ A detection angle that is approximately zero is searched.

  The sign determination circuit 441 determines whether the value of the rotation Y-axis component Vy ′ is positive or negative, and outputs a sign determination result sign. Although the above determination is based on 0, the code may be determined based on the magnitude of a predetermined offset value.

  The successive approximation register (SAR) 443 can appropriately rewrite the value by the sequencer 442 and outputs the value as detected angle data θd. In the present embodiment, the data word length is 6 bits.

  The sequencer 442 rewrites the value of the successive approximation register (SAR) 443 every time the trigger fs arrives, and determines the value of the successive approximation register (SAR) 443 based on the value of the sign determination result sign that changes as a result. Perform a search sequence.

  Hereinafter, the operation of the sequencer 442 will be described in detail with reference to FIGS.

  First, when the trigger fs arrives at the sequencer 442, the count n = 1 as shown in FIG. 14, and only the value of bit5 that is the most significant bit of the successive approximation register (SAR) 443 is set to 1, as shown in FIG. The values of all are 0. Note that rewriting the value of the successive approximation register (SAR) 443 is the same as changing the value of the detected angle data θd.

  The changed detection angle data θd is fed back to the vector rotation circuit 430, and the vector rotation circuit 430 rotates the vector (Vx, Vy) clockwise by θ1 = 180 °. If the rotation X-axis component Vx ′ and the rotation Y-axis component Vy ′ at this time are set to Vx ′ (1) and Vy ′ (1), respectively, the sequencer 442 uses the sign determination result sign as the sign of Vy ′ (1). If the sign is positive, the most significant bit 5 of the successive approximation register (SAR) 443 is determined to be 1.

  When the next clock clk arrives, the count n is set to 2 as shown in FIG. 14, and the value of bit 4 that is the second bit from the most significant bit of the successive approximation register (SAR) 443 is rewritten to 1 as shown in FIG. On the other hand, the value of bit5 is not rewritten because the determined value 1 may be maintained, and the values of other bits are not rewritten.

  The detected angle data θd changed again is fed back to the vector rotation circuit 430, and the vector (Vx, Vy) is rotated clockwise by θ1 + θ2 = 180 ° + 90 ° by the vector rotation circuit 430. Similarly, if the rotation results are Vx ′ (2) and Vy ′ (2), the sequencer 442 detects the sign of Vy ′ (2) based on the sign determination result sign, and if the sign is negative, it is a successive approximation. Bit4 of register (SAR) 443 is fixed to 0.

  When the next clock clk arrives, the count n = 3 as shown in FIG. 14, and the value of bit3 that is the third bit from the most significant bit of the successive approximation register (SAR) 443 is rewritten to 1 as shown in FIG. At the same time, the value of bit4 determined when n = 2 is also rewritten to 0, and the values of the other bits are not rewritten.

  The detected angle data θd changed again is fed back to the vector rotation circuit 430, and the vector (Vx, Vy) is rotated clockwise by θ1 + θ2-θ3 = 180 ° + 90 ° -45 ° by the vector rotation circuit 430. Similarly, if the rotation results are Vx ′ (3) and Vy ′ (3), the sequencer 442 detects the sign of Vy ′ (3) from the sign determination result sign, and if the sign is negative, the sequence approximation register (SAR) ) Set bit3 of 443 to 0.

  When the next clock clk arrives, the count n = 4 as shown in FIG. 14 and the value of bit 2 that is the fourth bit from the highest bit of the successive approximation register (SAR) 443 is rewritten to 1 as shown in FIG. At the same time, the value of bit3 determined when n = 3 is also rewritten to 0, and the values of other bits are not rewritten.

  The detected angle data θd that has been changed again is fed back to the vector rotation circuit 430, and the vector (Vx, Vy) is rotated clockwise by the vector rotation circuit 430 to θ1 + θ2-θ3-θ4 = 180 ° + 90 ° -45 ° -22.5. Rotate only °. Similarly, if the rotation results are Vx ′ (4) and Vy ′ (4), the sequencer 442 detects the sign of Vy ′ (4) from the sign determination result sign, and if the sign is positive, the sequential approximation register (SAR) ) Set bit2 of 443 to 1.

  The sequencer 442 repeats the above sequence 6 steps until n = 1 to 6. This corresponds to the word length of the successive approximation register (SAR) 443, and all bit values are determined. However, since only the last step has no next step, when the value of bit 0 of the successive approximation register (SAR) 443 is fixed to 0, rewriting processing is necessary.

  The operation of the sequencer 442 is generalized and described. The rotation angle θn (n = 1, 2,..., 6) of the vector (Vx ′ (n), Vy ′ (n)) is halved for each step. As the rotation direction, if the Y-axis component Vy ′ of the rotated vector is positive, the next step is clockwise, and if it is negative, the next step is counterclockwise, and the vector (Vx, Vy) is Rotate.

  Finally, the vectors (Vx ′ (n), Vy ′ (n)) rotate to the closest position to the X axis, and therefore the total rotation angle in the angle search sequence is the angle formed by the vector (Vx, Vy) and the X axis. Can be detected as This is an approximate search algorithm based on a so-called bisection method.

  As described above, it is possible to detect the detected angle data θd indicating the angle of the output shaft of the motor 210 with the X axis as a phase reference. At this time, a value obtained by adding a predetermined offset to the detected angle data θd is detected as a rotor angle, and detected angle data θd indicating the angle of the output shaft of the motor 210 is detected with a predetermined phase other than the X axis as a reference. Also good.

  The detected angle data θd determined as described above is input to the two-phase pulse generation circuit 450.

  The two-phase pulse generation circuit 450 refers to the lower two bits of the detected angle data θd every time the trigger fs arrives, and outputs the two-channel encoder equivalent signals ENC1 and ENC2 according to the generation logic shown in FIG.

  As described above, according to the rotational position detection circuit 222 using the vector method, the 2-channel encoder equivalent signal can be obtained by providing the rotational position detection circuit 222 in the driver circuit 220 without providing a rotary encoder on the output shaft of the motor 210. Obtainable.

  The vector-based rotational position detection circuit 222 described above is an example of a vector-based rotational position detection circuit. In addition to the configuration described above, each trigonometric function for the rotation angle of the output shaft of the motor 210 is calculated based on the differential signals U +, U−, V +, V− for at least two of the magnetic pole phase signals. A vector generation circuit 420 for generating a vector (Vx, Vy) having component values, and calculating the vector (Vx, Vy) by calculating the vector (Vx, Vy), the analog sine value Asin, and the analog cosine value Acos. A vector rotation circuit 430 that rotates and a vector rotation circuit 430 sequentially rotates the vectors (Vx, Vy) to obtain rotated vectors (Vx ′ (n), Vy ′ (n)), and detects the rotation angle. An angle search control circuit 440 that detects the angle data θd and two-channel encoder equivalent signals ENC1 and ENC2 based on the detected angle data θd. The rotational position detection circuit 222 including the obtained two-phase pulse generation circuit 450 can be used as appropriate.

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 101 Document conveying apparatus 1Y, 1M, 1C, 1K Photosensitive drum 2Y Drum cleaning apparatus 4Y Charging apparatus 5Y Developing apparatus 6Y, 6M, 6C, 6K Process cartridge 7 Exposure apparatus 8 Intermediate transfer belt 9Y, 9M, 9C, 9K Primary transfer bias roller 10 Belt cleaning device 12 Secondary transfer backup roller 13 Cleaning backup roller 14 Tension roller 15 Intermediate transfer unit 19 Secondary transfer roller 20 Fixing unit 26 Paper storage cassette 27 Paper feed roller 28 Registration roller pair 29 Paper discharge Roller pair 30 Stack unit 31 Bottle support unit 32Y, 32M, 32C, 32K Toner bottle 42 Document table 43 Moving document table 44 Set filler 45 Set sensor 47 Pickup roller 48 Table rise detection sensor 49 Paper feed belt 50 Reverse roller 51 Abutment sensor 52 Pull-out roller 53 Document width sensor 54 Intermediate roller 55 Reading entrance sensor 56 Reading entrance roller 57 Registration sensor 60 Reading position 63 Reading exit roller 64 Delivery sensor 65 2 Reading section 67 CIS exit roller 68 Paper discharge roller 69 Paper discharge tray 99 Paper 200-1, 200-2 Drive device 210 Motor 211, 212, 213 Hall element 220 Driver circuit 221 Motor drive circuit 222 Rotation position detection circuit 230-1 , 230-2 Control circuit 231 Target position / speed calculation circuit 232 Position / speed tracking controller 233 Motor position / speed calculation circuit 234 Target position calculation circuit 235 Position tracking controller 236 Motor position calculation circuit 240 Target drive signal Generation means 310 First phase detection circuit 320 Second phase detection circuit 330 Third phase detection circuit 340 Phase division circuit 350 Signal selection circuit 360 Synthesis circuit 321, 322, 323 Comparator 332-1 to 332-(N− 1) Voltage source 331-1 to 331-N Phase detector 410 Differential amplifier 420 Vector generation circuit 430 Vector rotation circuit 440 Angle search control circuit 450 Two-phase pulse generation circuit 421, 433 Subtraction amplifier 422, 432 Addition amplifier 423, 424 Sample hold circuit 431 Multiplier 434 Memory 441 Sign determination circuit 442 Sequencer

JP 09-047056 A JP 2007-097365 A

Claims (11)

A motor drive unit for supplying electric power to the motor in accordance with a magnetic pole phase signal output from the motor;
A rotational position detector that converts the magnetic pole phase signal to represent the rotational amount and rotational direction of the output shaft of the motor, and outputs a rotational position detection signal having a high resolution with respect to the magnetic pole phase signal;
A control device comprising:   The control unit for transmitting a control signal to the motor drive unit based on the rotation position detection signal output from the rotation position detection unit and a target drive signal input from a host device. The control apparatus according to 1.   The control device according to claim 2, wherein the motor driving unit and the rotational position detection unit are configured on the same substrate.   4. The control apparatus according to claim 2, wherein the rotational position detection unit and the means for generating the magnetic pole phase signal are configured on the same substrate.   The control device according to claim 2, wherein the motor driving unit and the control unit are configured on the same substrate.   The control device according to claim 2, wherein the motor drive unit and the control unit are configured on the same chip.   7. The control device according to claim 2, wherein the rotational position detection signal is a two-channel signal having a constant phase difference in which an output changes in accordance with a rotation angle of an output shaft of the motor. . The rotational position detector is
A signal selection unit that outputs a selection signal by selecting and connecting phase sections with high linearity among the magnetic pole phase signals;
A phase detector that detects the phase information of the magnetic pole phase signal by comparing the selection signal with a predetermined threshold;
A synthesizing unit that synthesizes the rotational position detection signal based on the phase information;
The control device according to any one of claims 2 to 7, further comprising: The rotational position detector is
A vector generation unit that performs a mutual operation on differential signals for at least two of the magnetic pole phase signals and generates a vector having a trigonometric function for the rotation angle of the output shaft as a value of each component;
A vector rotation unit for rotating the vector by calculating the vector and a reference sine wave;
An angle search control unit for detecting, as a rotation angle, an angle obtained by rotating the vector by the vector rotation unit until the vector reaches a predetermined phase;
A two-phase pulse generator for obtaining the rotational position detection signal based on the rotational angle;
The control device according to any one of claims 2 to 8, further comprising:   A drive device comprising the control device according to claim 2 and the motor.   An image forming apparatus comprising the driving device according to claim 10.

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