JP5434311B2 - Stepping motor control device and rotation control method - Google Patents

Description

  The present invention relates to a stepping motor control apparatus and a rotation control method for controlling a stepping motor, and more particularly to a tapping motor control apparatus and a rotation control method that can prevent step-out and reduce power consumption.

  A stepping motor may be used as a paper feed motor of an image forming apparatus. Since the stepping motor has the same number of input pulses as the position in the rotation direction (rotor position), speed feedback control is not required and can be controlled by a relatively simple control device. On the other hand, if the load torque exceeds the generated torque, a step-out occurs. Therefore, it is necessary to design the generated torque with a sufficient margin with respect to the assumed load torque.

  It is known that the motor output of a stepping motor is proportional to the magnetic flux density between the rotor and the stator, the number of coil turns, the coil current, and the load torque. A general stepping motor control device controls the motor output by adjusting the coil current. Therefore, in order to suppress the step-out of the stepping motor, it is necessary to flow a coil current through the coil that ensures a sufficient torque margin.

  However, the coil current with a sufficient torque margin to prevent step-out is excessive power with respect to the actual motor output (= load torque × rotational speed). This excess power is consumed as Joule heat in the coil.

  A technique for preventing the step-out while suppressing the coil current is also considered (see, for example, Patent Document 1). Patent Document 1 discloses a motor drive control device that sequentially reduces the drive current of a stepping motor, measures the coil current when the motor steps out, and determines the drive current during normal operation based on this. Yes.

  Further, a technique for adjusting the coil current is considered (for example, see Patent Document 2). Patent Document 2 discloses a technique for adjusting the coil current so that the load torque of the motor and the generated torque have a substantially constant relationship for the purpose of suppressing the vibration of the stepping motor.

  However, the technique described in Patent Document 1 still has a problem that excessive power is consumed even if step-out is prevented. Further, in the technique disclosed in Patent Document 2, in order to prevent step-out, the coil current is determined based on the maximum value of the load torque, so that an excessive coil current flows for a load torque lower than the maximum value. For this reason, there is a problem that power is always excessively consumed for a load torque lower than the maximum value.

  In view of the above problems, an object of the present invention is to provide a tapping motor control device and a rotation control method that prevent step-out and reduce excessive coil current.

  In order to solve the above-mentioned problems, the present invention is a stepping motor control device that outputs coil current value information and pulse frequency information to a stepping motor drive circuit, and changes the coil current value for one pulse frequency, and Motor efficiency determining means for determining the motor efficiency of the stepping motor, step out presence / absence determining means for determining whether or not the stepping motor is out of step, motor efficiency information and step out in association with pulse frequency information and coil current value information Table generating means for generating a table in which presence / absence is registered, and a coil having the highest motor efficiency without step-out among a plurality of coil current value information associated with pulse frequency information based on the rotation speed of the stepping motor A selection means for selecting current value information from the table, and a copy selected by the selection means. The tail current value information, and having a control information output means for outputting to said driving circuit.

  By generating a table in which motor efficiency information and step-out presence / absence are registered in association with pulse frequency information and coil current value information, it is possible to determine the coil current value with the highest motor efficiency without step-out. it can. Therefore, the coil current value with the least excess power can be determined in the driving torque that overcomes the load torque.

  It is possible to provide a tapping motor control device and a rotation control method that prevent step-out and reduce excessive coil current.

It is an example of the figure which shows the relationship between a driving torque, rotational speed, motor efficiency, and rotational speed. 1 is an example of a schematic configuration diagram of an image forming apparatus. It is a figure which shows an example of the functional block diagram of a stepping motor control apparatus. It is a figure which shows an example of an initial look-up table. It is an example of the block diagram of a motor driver. It is an example of the flowchart figure which shows the procedure in which a stepping motor control apparatus registers a coil current into motor efficiency and step-out presence / absence in a lookup table. It is a figure which shows an example of the produced | generated lookup table. It is an example of the flowchart figure of the procedure in which a coil current selection part selects a coil current. It is an example of the functional block diagram of a stepping motor control apparatus (Example 2). It is an example of the flowchart figure which shows the procedure in which a stepping motor control apparatus registers a coil current into motor efficiency and step-out presence / absence in a lookup table. (Example 2). It is an example of the flowchart figure which shows the procedure in which a stepping motor control apparatus registers a coil current into motor efficiency and step-out presence / absence in a lookup table. (Example 2 modification). It is an example of the functional block diagram of a stepping motor control apparatus (Example 3). It is an example of a schematic perspective view of a paper feed driving roller. (Example 3) which is an example of the flowchart figure which shows the procedure in which a stepping motor control apparatus registers a coil current into motor efficiency and step-out presence / absence in a lookup table. It is an example of the functional block diagram of a stepping motor control apparatus (Example 4). (Example 4) which is an example of the flowchart figure which shows the procedure in which a stepping motor control apparatus registers a coil current in a lookup table about motor efficiency and the presence or absence of a step-out. It is an example of the functional block diagram of a stepping motor control apparatus (Example 5). (Example 5) which is an example of the flowchart figure which shows the procedure in which a stepping motor control apparatus registers a coil current into motor efficiency and step-out presence / absence in a lookup table. It is an example of the functional block diagram of a stepping motor control apparatus (Example 6). (Example 6) which is an example of the flowchart figure which shows the procedure in which a stepping motor control apparatus registers a coil electric current in a lookup table about motor efficiency and step-out presence / absence.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

  The stepping motor control apparatus 100 according to the present embodiment generates and stores a lookup table in which pulse frequency, coil current, motor efficiency, and step-out presence / absence are associated with each other. In the lookup table, a plurality of coil currents, motor efficiency, and step-out presence / absence are associated with the same pulse frequency. Then, the stepping motor control device 100 refers to the look-up table when driving the stepping motor, and has the highest motor efficiency without causing step-out from a plurality of coil currents according to the pulse frequency (motor rotation speed). Select the coil current.

  As shown in FIG. 1A, the drive torque tends to be inversely proportional to the rotational speed. Further, the driving torque is larger as the coil current is larger. As shown in FIG. 1B, the motor efficiency tends to be proportional to the rotational speed and inversely proportional to the coil current. Therefore, in order to obtain a sufficient driving torque (in order to prevent step-out), if the coil current is increased, the motor efficiency decreases, and if the coil current is decreased to increase the motor efficiency, the driving torque decreases and step-out occurs. It becomes easy. Therefore, it is difficult to intuitively and theoretically determine the coil current having the highest motor efficiency without being stepped out.

  In this embodiment, by registering the correspondence between step-out presence / absence and motor efficiency in the lookup table in association with the coil current, the most efficient coil current that does not step out even when the load torque is relatively low. Can drive the stepping motor.

[Outline of image forming apparatus]
The image forming apparatus 200 is, for example, a copier, a printer, a facsimile, or an MFP (Multifunction Peripheral) having one or more of these functions. Further, a scanner function may be provided. The charge control device 100 of this embodiment can be suitably applied to the electrophotographic image forming apparatus 200.

  FIG. 2 shows an example of a schematic configuration diagram of the image forming apparatus 200. The image forming apparatus 200 in FIG. 2 is called an MFP. The MFP includes an automatic document feeder (ADF) 1000, a scanner unit 2000, an image forming unit 3000, and a paper feed unit 4000. The scanner unit 2000 conveys documents placed on the ADF 1000 or the document feeder 11 onto the contact glass 21 one by one, reads the image data from the document, and then ejects the document onto the sheet discharge tray 18. Specifically, the document set on the document feeder 11 is aligned in the width direction of the sheet by a side fence (not shown), separated from the lowest document by the sheet feed roller 12, and fed. It is conveyed on the contact glass 21 by the conveyance belt 19. The feeding unit 15 is provided with a document width detection sensor 13 and a document length detection sensor 14, which can detect the size (B5, A4, B4, etc.) of the document conveyed from the ADF 1000. The original on the contact glass 21 is discharged onto the paper discharge tray 18 by the conveying belt 19 and the paper discharge roller 16 after the reading of the image data is completed, and a series of operations is completed.

  Further, at the time of double-sided copying, the original is fed by the paper feed roller 12, passes through the contact glass 21 by the conveying belt 19, is reversed by the reversing claw 17, and is then conveyed again onto the contact glass 21, so The back side is read. Next, the document is transported by the transport belt 19, reversed by the reversing claw 17, and then transported onto the contact glass 21 again to read the surface of the document. Then, the document on the contact glass 21 is discharged onto the paper discharge tray 18 by the transport belt 19 and the paper discharge roller 16.

  The scanner unit 2000 includes a contact glass 21 for placing a document and an optical scanning system 20. The optical scanning system 20 includes an exposure lamp 23, a first mirror 26, a second mirror 24, a third mirror 25, a lens 22, and a full color CCD 27. The exposure lamp 23 and the first mirror 12 are mounted on a first carriage (not shown), and the first carriage moves in the sub-scanning direction at a constant speed by a stepping motor when reading a document. The second mirror 24 and the third mirror 25 are mounted on a second carriage (not shown), and the second carriage moves at a speed approximately half that of the first carriage by a stepping motor when reading a document. As the first carriage and the second carriage move, the image surface of the document is optically scanned, and the read data is imaged on the light receiving surface of the full-color CCD 27 by the lens 22 and subjected to photoelectric conversion. Image data photoelectrically converted into red (R), green (G), and blue (B) colors by the full color CCD 27 is A / D converted and subjected to various image processing.

  Further, when copying, image data is copied onto the paper by the image forming unit 3000. The image forming unit 3000 includes a laser output unit 28, an fθ lens 27, and a mirror 29. The laser output unit 28 includes a laser diode (LD), a polygon mirror, and a polygon motor. Around the photoreceptor 35, a charging roller 30, a black developing device 31, an LED writing unit 33 for writing an image of a red signal, a red developing device 34, a transfer device and a separator (not shown) are arranged.

  The charging roller 30 is a non-contact type charging roller as will be described later. The charging roller 30 is applied with an AC + DC voltage by the charging control device 100 and charges the peripheral surface of the photoreceptor 35. The laser output unit 28 emits a black signal laser beam modulated in accordance with an image read by a scanner during copying. The laser beam is guided so as to scan the peripheral surface of the photosensitive member 35 charged by the mirror 29 in the main scanning direction. As a result, a latent image is formed on the photoreceptor 35.

  The black developing device 31 and the red developing device 34 form a toner image (image visualized with toner) on the peripheral surface of the photoreceptor 35 by attaching toner to the latent image formed image. As described below, the sheet is conveyed to the transfer device 40 at a predetermined timing, and the toner image is transferred to the sheet by the transfer device 40. The toner remaining on the surface of the photoconductor 35 is removed by a cleaning device including a blade that is in sliding contact with the peripheral surface of the photoconductor 35.

  The sheet is selected from any of the duplex unit 46 in the image forming apparatus 200, the first tray 57, the second tray 54 in the sheet feeding unit 4000, the third tray 55, and the fourth tray 56. The selected paper is fed by the feed roller 43 and the separation roller 47, the first paper feeding device 48, the second paper feeding device 49, the third paper feeding device 51, or the fourth paper feeding device 52.

  The paper fed from the duplex unit 46 and the first tray 57 is transported upward by the vertical transport unit 45, and the second paper feeder 49, the third paper feeder 51, or the fourth paper feeder 52. Is fed via the bank vertical conveyance unit 53 and the vertical conveyance unit 45. Then, when a predetermined time elapses after the leading edge of the sheet is detected by the registration sensor 42, the sheet is abutted against the registration roller 41 and stops once. Further, the sheet is conveyed by the rotation of the registration roller 41 in synchronization with the sub-scanning effective period signal (FGATE), and the toner image on the photoconductor 35 is transferred.

  Next, the sheet is separated from the photoreceptor 35 by a separator (not shown), and then conveyed to the fixing device 37 by the conveying device 36, and the toner image is fixed by heat and pressure by the fixing device 37. The paper after fixing is discharged onto the paper discharge tray 53 by the switching claw 39 and the paper discharge roller 38 during single-sided printing and double-sided printing during double-sided printing.

  The stepping motor control apparatus 100 according to the present embodiment controls a coil current supplied to a stepping motor that rotationally drives the paper feed roller 12. However, any stepping motor can be suitably applied to the paper discharge roller 16 and the feed roller 43.

[Overall Configuration of Stepping Motor Control Device 100]
FIG. 3 is a diagram illustrating an example of a functional block diagram of the stepping motor control device 100. The stepping motor control device 100 is controlled by the CPU 65. The power (voltage / current) supplied from the power supply 61 is supplied to the stepping motor 66 via the power supply voltage / current detection circuit 62. The power supply voltage / current detection circuit 62 is connected to the CPU 65.

  A motor driver 64, a torque sensor 68, a rotary encoder 69 and a ROM 63 are connected to the CPU 65. The motor driver 64 is connected to a stepping motor 66, the stepping motor 66 is connected to a paper feed drive shaft 67, and the paper feed drive shaft 67 is connected to a torque sensor 68 and a rotary encoder 69.

  The power source 61 is connected to a commercial AC power source, and converts the AC power source into a DC current and voltage suitable for driving the stepping motor 66. In this embodiment, the upper limit of the voltage for driving the stepping motor 66 is 24 [V]. The power supply voltage / current detection circuit 62 detects the voltage value and current value supplied by the power supply 61 and transmits them to the CPU 65 as an analog voltage signal.

  The rotary encoder 69 transmits a pulse signal to the CPU 65 every time the paper feed drive shaft 67 rotates by a predetermined angle. The CPU 65 detects the rotation speed of the paper feed drive shaft 67 from the number of pulse signals per unit time. In this embodiment, the gear ratio of the pair of gears that rotate integrally with the rotation shaft of the stepping motor 66 and the paper feed drive shaft 67 is “1: 1”. Therefore, the rotation speed of the paper feed drive shaft 67 is the same as the motor rotation speed of the stepping motor 66.

  The torque sensor 68 detects a load torque obtained by converting the twist angle of the paper feed drive shaft 67 into an electric signal. The torque sensor 68 transmits the detected load torque to the CPU 65 as an analog voltage signal. The CPU 65 A / D converts this to acquire the load torque.

In the ROM 63, function information 85 relating to an expression to be described later is stored in advance. The ROM 63 stores a lookup table 84.
FIG. 4 is a diagram illustrating an example of the initial lookup table 84. In the initial lookup table 84, only the pulse frequency and the coil current are registered. “Initial” means a factory shipment state.

  Once the lookup table 84 is generated (after blanks are filled), the stepping motor control device 100 updates the lookup table 84 at a predetermined timing. Therefore, the motor efficiency and the presence / absence of step-out are updated as appropriate. Thus, by updating the look-up table in a relatively short period, the stepping motor 66 can always be driven with a coil current with high motor efficiency. For example, even when the attachment angle of the paper feed roller changes over time, the stepping motor can always be driven with a coil current with high motor efficiency.

  The pulse frequency [Pulse Per Second] registered in FIG. 4 is determined according to the number of rotations that the stepping motor 66 can take. In the figure, three types of pulse frequencies of 1200, 1800, and 2400 are registered corresponding to the motor rotation speed that can be changed in three stages. In the coil current, several possible values (six values in the figure) are registered. Although the stepping motor 66 is controlled at a constant current, the coil current is variable within a certain range, and a preferable range of the coil current can be determined from a lower limit due to a required driving torque and an upper limit capable of allowing heat generation. A higher driving torque is obtained as the coil current is higher.

  Then, the stepping motor control device 100 according to the present embodiment determines a coil current with high motor efficiency for the same pulse frequency. For this reason, the stepping motor control device 100 calculates the “motor efficiency” at the timing of adjusting the coil current, such as during the warming up of the image forming apparatus or after paper jam recovery, and determines whether or not there is a step-out. Register the "motor efficiency" and "step-out occurrence" in the lookup table. Note that “pulse frequency (PPS)” is sorted in ascending order and “coil current” is sorted in descending order in consideration of the efficiency of the procedure for measuring motor efficiency.

  Returning to FIG. 3, the ROM 63 stores a program 86 to be executed by the CPU 65. The program 86 is stored in the ROM 63 when the image forming apparatus 200 is shipped. Further, since the data is distributed in a state stored in the storage medium 72 for version upgrade or the like, the user can install the read program 86 in the ROM 63 by mounting the storage medium 72 on the USB I / F 71. it can. The image forming apparatus may receive from a server (not shown) via a NIC (Network Interface Card) and may be installed in the ROM 63. Therefore, the ROM 63 may be a rewritable nonvolatile memory such as a flash memory, FeRAM (Ferroelectric Random Access Memory), or MRAM (Magnetoresistive Random Access Memory).

  The CPU 65 executes the program 86 to associate the pulse frequency, the coil current, the motor efficiency, and the presence / absence of step-out with the lookup table 84 and register the lookup table 84 for each pulse frequency. , A coil current selection unit 82 that selects a coil current value with the highest motor efficiency without step-out from a plurality of coil current value setting candidates, and a motor that drives the stepping motor 66 with the selected coil current value And a drive unit 83. Further, the table generation unit 81 includes a motor efficiency calculation unit 81a that calculates motor efficiency and a step-out presence / absence determination unit 81b that determines whether or not step-out occurs.

  The motor efficiency calculation unit 81 a calculates “motor output” from the “motor rotation speed” detected by the rotary encoder 69 and the “load torque” detected by the torque sensor 68 using the function information 85 stored in the ROM 63. To do. This function will be described later. The motor efficiency calculation unit 81 a calculates “power consumption” from the “power supply voltage” and “power supply current” detected by the power supply voltage / current detection circuit 62 using the function information 85 stored in the ROM 63. Then, the motor efficiency calculation unit 81 a calculates “motor efficiency” from the calculated “motor output” and “power consumption” using the function information 85 stored in the ROM 63. The motor efficiency calculation unit 81a performs the above calculation for each combination of the pulse frequency and the coil current. Then, the table generation unit 81 generates a lookup table 84 in which “pulse frequency (PPS)”, “coil current”, and “motor efficiency” are associated. The determination of the presence or absence of step-out will be described later.

  The coil current selection unit 82 selects a coil current to be set for the motor driver 64 from the lookup table 84. The motor drive unit 83 converts the selected coil current into a coil current setting signal and transmits it to the motor driver 64. Further, the motor driving unit 83 transmits a pulse frequency to the motor driver 64 in order to control the rotation speed of the stepping motor 66. In addition, the motor drive unit 83 transmits an excitation method setting signal that specifies the excitation method of the stepping motor 66 to the motor driver 64.

  The motor driver 64 generates an excitation signal (serial data) according to the pulse frequency signal and the excitation method setting signal transmitted from the CPU 65 and drives the stepping motor 66. Further, the motor driver 64 determines a “coil current value” in accordance with the coil current setting signal transmitted from the CPU 65, and performs chopping control using the current value.

  FIG. 5 shows an example of a block diagram of the motor driver 64. In FIG. 5, the stepping motor 66 is described as a stepping motor 66 capable of one-phase excitation, two-phase excitation, 1-2 phase excitation, and 2-1 phase excitation. The excitation method may be any mode.

  The motor driver 64 can make the coil current further variable based on the constant current driving method. The coil current setting signal (voltage value) is input to the comparison circuits 75a and 75b and compared with the voltage of the current detection resistor Rs that detects the current flowing through the coil. The chopping control circuits 74a and 74b supply the coil current to the stepping motor 66 while the coil current is smaller than the coil current setting signal, and supply the coil current to the stepping motor 66 when the coil current exceeds the coil current setting signal. To stop doing. Therefore, the coil current flowing through the stepping motor 66 is controlled to a constant current indicated by the coil current setting signal.

  The sequencer circuit 73 creates serial data corresponding to the A phase, -A phase, B phase, and -B phase of the stepping motor 66 based on the pulse frequency signal input from the CPU 65. For example, when two-phase excitation is specified by the excitation method setting signal, (A phase on, B phase on), (-A phase on, B phase on), (-A phase on, -B phase on), ( (A phase on, -B phase on), (A phase on, B phase on), (-A phase on, B phase on), (-A phase on, -B phase on), (A phase on, -B Serial data that repeats (phase on).

  The sequencer circuit 73 controls on / off of the switch circuits 76a, 77a, 76b, and 77b based on the serial data. The on / off timing (how much the state of each switch circuit 76a, 77a, 76b, 77b is maintained with respect to the supplied clock) is defined in advance by a pulse frequency signal.

[Control procedure for determining coil current]
FIG. 6 is an example of a flowchart illustrating a procedure in which the stepping motor control device 100 registers the coil current in the lookup table with the motor efficiency and the step-out status. The procedure in FIG. 6 starts when a “coil current adjustment” request is received from the system control module of the image forming apparatus 200 to the stepping motor control apparatus 100. For example, the timing when the “coil current adjustment” request comes from the system control module side is assumed to be during warming up or after paper jam recovery.

  When the CPU 65 receives a “coil current adjustment” request from the system control module, the table generation unit 81 is activated, and the table generation unit 81 activates a “coil current adjustment routine” (S1). Since the coil current should not be adjusted while the paper feed motor is rotating, the table generator 81 confirms that the paper feed motor has stopped. The reason for this is to confirm the presence or absence of step-out at the time of motor startup when the load is most applied to the paper feed motor 12 (at the time of motor startup, acceleration torque is applied in addition to load torque). That the paper feed motor is stopped is detected because the rotary encoder 69 does not output a pulse signal.

  The table generator 81 refers to the lookup table 84 stored in the ROM 63, measures the motor efficiency, and determines a set of “pulse frequency” and “coil current” that determines whether or not step-out occurs (step S2). The minimum value among the plurality of “pulse frequencies” in the lookup table 84 is treated as an “initial value”, and the maximum value among the plurality of “pulse frequencies” is treated as an “upper limit value”. Similarly, the maximum value among the plurality of “coil currents” is treated as the “initial value”, and the minimum value among the plurality of “coil currents” is treated as the “lower limit value”.

The motor efficiency is calculated in steps S3 to S17. Here, an outline of the motor efficiency calculation procedure (steps S3 to S17) will be described.
(1) First, the table generating unit 81 changes the coil current while keeping the pulse frequency (PPS) at a constant value, and detects “load torque” and “power supply voltage / current” each time the change is made. When the set coil current reaches the “lower limit value”, the table generating unit 81 ends the measurement of “load torque” and “power supply voltage / current” at the pulse frequency. Moreover, the table production | generation part 81 complete | finishes the measurement in the pulse frequency also when detecting a step-out of a motor.
(2) Next, the table generation unit 81 changes the pulse frequency and repeats the procedure of (1).
(3) When the “upper limit value” of the pulse frequency is reached, the table generator 81 completes the measurement of the motor efficiency.

Returning to step S3, the details will be described.
The table generating unit 81 sets “initial value” to “target PPS” (S3). The table generator 81 changes the coil current while maintaining the motor rotation speed at a constant value of the target PPS. Further, the table generating unit 81 sets “initial value” to “coil current” (S4). Since the largest coil current becomes the initial value, the calculation of the motor efficiency can be started from the condition where the step-out is most difficult.

  Based on the pulse current as the target PPS and the coil current, the motor driving unit 83 activates the paper feed motor according to the content of the feed motor through-up table stored in advance in the ROM 63 (S5). That is, the motor drive unit 83 gradually increases the rotational speed according to the through-up table.

  The motor efficiency calculation unit 81a starts detecting “motor rotational speed (rad / s)” based on the pulse signal transmitted from the rotary encoder 69 (S6). The motor driving unit 83 continuously controls the motor rotation speed until the “motor rotation speed (rotation speed of the paper feed drive shaft 67)” reaches the motor rotation speed corresponding to the “target PPS”.

The “motor rotation speed” is calculated from the pulse frequency output from the rotary encoder 69 by the following equation.
“Motor rotational speed (rad / s)” = “Output pulse frequency (Hz) ÷ Encoder resolution (P / R)” × 2π (1)
Further, the motor rotation speed corresponding to the “target PPS” is calculated by the following equation.
“Motor rotational speed (rad / S)” = {“Target PPS (Hz)” ÷ (360 ÷ “Motor basic step angle (°)”)} × 2π (2)
By the way, when the stepping motor 66 steps out, the “motor rotational speed (rotational speed of the paper feed drive shaft 67)” does not reach the target motor rotational speed corresponding to the “target PPS”. In the present embodiment, if the motor rotation speed does not reach the target motor rotation speed within a predetermined time after starting the stepping motor 66, the step-out presence / absence determination unit 81b determines that the alarm has been lost. This predetermined time (for example, several seconds) is experimentally determined in advance. It may be registered in the lookup table 84.

  For this reason, when the “motor rotation speed” does not reach the target motor rotation speed by the determination in step S7 (No in S7), the step-out presence / absence determination unit 81b determines whether or not the predetermined step has elapsed. It is determined whether or not (S8).

  As a result, when the “motor rotation speed” reaches the target motor rotation speed within a predetermined time (Yes in S7), the process proceeds to step S9.

  On the other hand, when the “motor rotation speed” does not reach the target motor rotation speed within a predetermined time (Yes in S8), the step-out presence / absence determination unit 81b determines that the alarm has occurred. When it is determined that the motor has stepped out (Yes in S8), the motor driving unit 83 stops the stepping motor 66 (S11). Then, the table generating unit 81 registers “0 (%)” in the “motor efficiency” column of the lookup table 84 and “1 (out of step)” in the “out of step” column (S21).

  Further, the table generation unit 81 stores “0 (%)” in the remaining “motor efficiency” column and “out of step” column in the lookup table 84 for the pulse frequency of the currently set target PPS. "1 (step out)" is registered (S22). This is because when the coil currents registered in descending order are stepped out at a certain coil current, they may be stepped out at a smaller coil current.

  Further, the table generating unit 81 sets “next set value” in the lookup table 84 to “target PPS” (S23). Here, the “next set value” is the next highest pulse frequency after the “current set value” in the lookup table 84. That is, the process proceeds to calculation of motor efficiency at the next pulse frequency. By doing so, the calculation of the motor efficiency of the lookup table 84 can be completed in a shorter time.

Returning to step S9, the motor efficiency calculator 81a detects the load torque (S9). The motor efficiency calculation unit 81 a calculates “load torque” from the output voltage detected by the torque sensor 68 using the following equation. However, in Formula (3), it is “A: Conversion coefficient”.
“Load torque (N · m)” = “Torque sensor output voltage (V)” × A (3)
Next, the motor efficiency calculation unit 81a uses the “power supply voltage” detected by the power supply voltage / current detection circuit 62 to calculate the voltage value of the stepping motor drive power supply from the following equation (S10). However, in equation (4), “B: conversion coefficient”.
“Voltage value (V)” = “Power supply voltage (V)” × B (4)
Similarly, the motor efficiency calculation unit 81a calculates the current value of the stepping motor drive power supply from the following equation using the “current voltage” detected by the power supply voltage / current detection circuit 62. However, in equation (5), “B: conversion coefficient”.
“Current value (A)” = “Power supply current (V)” × C (5)
Thereby, since the information required for motor efficiency was obtained, the motor drive part 83 stops a motor (S11). The motor driving unit 83 stops the stepping motor 66 according to the content of the through-down table of the paper feed motor stored in advance in the ROM 63.

Then, the motor efficiency calculation unit 81a calculates “motor output” from the “load torque” calculated by the equation (3) and the “motor rotation speed” calculated by the equation (1) using the equation (6). (S12).
“Motor output (W)” = “Motor load torque (N · m)” × “Motor rotation speed (rad / S)” (6)
Further, the motor efficiency calculation unit 81a uses the expression (7) from the “voltage value (V)” calculated from the expression (4) and the “current value (A)” calculated from the expression (4), "Power consumption" is calculated. (S12).
“Power consumption (W)” = “Power supply voltage (V)” × “Power supply current (A)” (7)
Further, the motor efficiency calculation unit 81a calculates “motor efficiency” from the “motor output” calculated by the equation (6) and the “power consumption” calculated by the equation (7) using the equation (8). .
“Motor efficiency (%)” = “Motor output (W)” ÷ “Power consumption (W)” (8)
As described above, the table generation unit 81 registers “motor efficiency” calculated by Expression (8) in the “motor efficiency” column of the lookup table 84. In addition, the fact that the motor efficiency has been calculated means that no step-out has occurred, so the table generating unit 81 registers “0 (normal)” in the column of “step-out presence / absence” (S13).

  Next, the table generating unit 81 determines whether or not the current “coil current” is the “lower limit value” (S14). Since the coil currents are sorted in descending order, when the “lower limit value” is reached, the calculation of the motor efficiency is completed for all sets of the target PPS and the coil current. Therefore, when the “coil current” is not the “lower limit value” (No in S14), the table generating unit 81 sets the next smaller coil current in the lookup table 84 as the “coil current” (S15). For example, in the example of FIG. 4, when the “current set value” is “1.2A”, the “next set value” is “1.0A”.

  When the “coil current” is the “lower limit value” (Yes in S14), the table generating unit 81 determines whether the currently set “target PPS” is the “upper limit value” (S16). Since the lookup table 84 is sorted in ascending order with respect to the pulse frequency, if the “target PPS” is the “upper limit value”, the blank of the lookup table 84 is filled for all the pulse frequencies, or That is, the lookup table 84 is updated.

  Therefore, when the “target PPS” is not the “upper limit value” (No in step S16), the table generating unit 81 sets the “next set value” in the lookup table 84 to the “target PPS” (S17). Here, the “next set value” refers to the next highest pulse frequency after the “current set value” in the lookup table 84. For example, in FIG. 4, when the “current set value” is “1200 Hz”, the “next set value” is “1800 Hz”. Then, the table generation unit 81 repeats the processing from step S4 for the newly set “target PPS”.

  If the “target PPS” is the “upper limit value” (Yes in step S16), the lookup table 84 is referred to and the coil current selection unit 82 determines the coil current if necessary (S18), and the table is generated. The unit 81 ends the “coil current adjustment routine” (S19). The table generation unit 81 notifies the system control module side that “coil current adjustment” has been completed.

[Selection of coil current with reference to lookup table 84]
With the above processing, the lookup table 84 is generated.
FIG. 7 is a diagram illustrating an example of the generated lookup table 84. In association with “pulse frequency” and “coil current”, “motor efficiency” and “step-out presence / absence” are registered. As described above, when “step out” is performed, “motor efficiency” is “zero”.

When the stepping motor 66 is driven, the coil current selection unit 82 refers to the lookup table 84 and selects the coil current with the highest motor efficiency.
FIG. 8 is an example of a flowchart of a procedure in which the coil current selection unit 82 selects a coil current.

  First, the coil current selection unit 82 determines the pulse frequency from the rotation speed of the stepping motor requested from the system control module. Then, the coil current selection unit 82 reads “coil current”, “motor efficiency”, and “step-out presence / absence” associated with the pulse frequency from the lookup table 84 (S110).

  Then, the coil current selection unit 82 excludes “motor current” having “step-out presence / absence” of “1” from selection targets (S120).

  Next, the coil current selection unit 82 extracts a coil current having the highest motor efficiency (S130). For example, when the pulse frequency is “1200”, since the highest motor efficiency is “35%”, the coil current selection unit 82 uses “0.6 A” associated with the motor efficiency of “35%” as the coil current. Extract.

  Further, for example, when the pulse frequency is “1800”, the highest motor efficiency is “31%”, so the coil current selection unit 82 uses “1.0 A” corresponding to the motor efficiency of “31%” as the coil. Extract to current. When the pulse frequency is “1800”, the coil efficiency may be selected because there is a minimum coil current “0.8 A” even if the motor efficiency is not the highest. For example, the coil current selector 82 may focus directly on the coil current if the motor efficiency does not change significantly. For example, the difference in motor efficiency between the highest and next points (in FIG. 7, “(31−28) / 31 × 100” <within 10%) is the difference between the highest and next point coil currents (“(1. If it is sufficiently smaller than 0-0.8) /1.0 "<20%), it is also possible to extract the smallest coil current.

  Further, the coil current selection unit 82 determines whether or not there is a plurality of highest motor efficiencies (S140). When there are a plurality of highest motor efficiencies (Yes in S140), the coil current selection unit 82 selects the smallest coil current from a plurality of coil currents associated with the highest motor efficiency (S150). By doing so, power consumption can be reduced if the motor efficiency is the same.

  When there is not a plurality of highest motor efficiencies (No in S140), the coil current selection unit 82 selects the coil current extracted in Step S130 as the coil current (S160).

  With the above selection, “0.6 A” is obtained when the pulse frequency is “1200”, “1.0 A” is obtained when the pulse frequency is “1800”, and “1.2 A” is obtained when the pulse frequency is “2400”. Selected.

  The motor driving unit 83 converts the selected coil current value into a coil current setting signal and outputs the coil current setting signal to the motor driver 64. Thereby, the motor driver 64 drives the stepping motor 66 with the selected coil current value constant.

  As described above, the stepping motor control device 100 according to the present embodiment has the highest efficiency among the coil currents that do not step out by checking the coil current and the “motor efficiency” and “out of step”. The stepping motor 66 can be driven by selecting the coil current.

  In the first embodiment, when the “timing for adjusting the coil current” is reached, the lookup table 84 is updated, but the motor efficiency does not vary so rapidly. Therefore, in this embodiment, when the accumulated operating time of the stepping motor 66 exceeds a predetermined re-update time, the motor efficiency and the presence / absence of step-out are registered in the lookup table 84 according to the same flowchart as FIG. The stepping motor control device 100 will be described.

  FIG. 9 is a diagram illustrating an example of a functional block diagram of the stepping motor control device 100. 9, the same parts as those in FIG. 3 are denoted by the same reference numerals, and the description thereof is omitted. The stepping motor control apparatus 100 according to the present embodiment includes a re-update time elapsed measurement unit 87 that is realized by the CPU 65 executing the program 86.

  The re-update time elapsed measurement unit 87 stores “re-update time” as a parameter (as part of the instruction code). Then, the re-update time elapsed measurement unit 87 measures and accumulates the time during which the stepping motor 66 is actually rotating. For example, the re-update time elapsed measurement unit 87 sets a flag when actually rotating from a pulse signal detected by the rotary encoder, and measures the time during which the flag is set.

  The re-update time elapsed measurement unit 87 stores the accumulated time in the ROM 63 at any time while updating the accumulated time. For example, each time the main power of the image forming apparatus is turned on, the re-update time elapsed measurement unit 87 compares the re-update time with the accumulated time, and if the accumulated time exceeds the re-update time, the re-update time The progress measurement unit 87 requests the table generation unit 81 to update the lookup table 84. When updated, the update time elapsed measuring unit 87 resets the accumulated time.

  FIG. 10 is an example of a flowchart illustrating a procedure in which the stepping motor control apparatus 100 registers the coil current in the look-up table for the motor efficiency and the step-out status. The procedure in FIG. 10 starts, for example, every time the main power supply of the image forming apparatus is turned on.

  The re-update time elapsed measurement unit 87 determines whether or not the accumulated time stored in the ROM 63 has reached the re-update time (S310). If the integration time has not reached the re-update time (No in S310), the lookup table 84 is not updated, and the processing in FIG. 10 ends.

  When the accumulated time has reached the re-update time (Yes in S310), the re-update time elapsed measurement unit 87 updates the look-up table 84 to the table generation unit 81 because it is the timing to update the lookup table 84. A request is made (S320).

  Thereby, the table generation unit 81 updates the lookup table 84 in the same manner as in the first embodiment (S330). The processing in step S330 is the same as steps S1 to S23 in FIG.

  According to the present embodiment, in addition to the effects of the first embodiment, the look-up table 84 is updated every time when load torque aging (gear wear, etc.) occurs, so that a high motor efficiency state is maintained. be able to.

<Modification>
Finally, the date and time when the look-up table 84 is updated is stored in the ROM 63, and the period after the look-up table 84 is simply updated is compared with the required update time. May be updated. In this case, the re-update time elapsed measurement unit 87 acquires the current date and time from the system control module. The system control module continuously holds the current date and time by the calendar function.

  Then, the re-update time elapsed measurement unit 87 needs to update the elapsed time read from the ROM 63, from the "date and time when the lookup table 84 was last updated" to the "current date and time". Determine if the time has been exceeded. If it has exceeded, the re-update time elapsed measurement unit 87 requests the table generation unit 81 to update the lookup table 84.

  FIG. 11 is an example of a flowchart illustrating a procedure in which the stepping motor control device registers the coil current in the look-up table for motor efficiency and step-out presence / absence. The procedure of FIG. 11 is started each time the main power source of the image forming apparatus is turned on, for example.

  The re-update time elapsed measurement unit 87 calculates the required update time from the “current date / time” acquired from the system control module and the “date / time and date / time when the lookup table was last updated” read from the ROM 63. As described above, it is determined whether or not it has elapsed (S311).

  If the update required time or more has not elapsed since the “date and time when the lookup table was last updated” (No in S3110), the lookup table 84 is not updated, and the processing in FIG. 11 ends.

  If more than the necessary update time has elapsed since the "date and time when the lookup table was last updated" (Yes in S3110), the timing for updating the lookup table 84 is reached, so the re-update time elapsed measurement unit 87 The table generator 81 is requested to update the lookup table 84 (S321).

  Thereby, the table generation unit 81 updates the lookup table 84 in the same manner as in the first embodiment (S330). The processing in step S330 is the same as steps S1 to S23 in FIG.

  Further, the re-update time elapsed measurement unit 87 stores the date and time when the lookup table 84 is updated in the ROM 63 (S341).

  In this modified example, as in the second embodiment, in addition to the effects of the first embodiment, the look-up table 84 is updated every time when a change in load torque with time (such as gear wear) occurs, the motor efficiency is improved. High state can be maintained.

  In the second embodiment, the update timing of the lookup table 84 is determined based on the accumulated operation time of the stepping motor 66 or the elapsed time since the last update. In this embodiment, the integration of the drive transmission unit of the stepping motor 66 is determined. The stepping motor control device 100 that determines the update timing from the travel distance will be described.

  FIG. 12 is a diagram illustrating an example of a functional block diagram of the stepping motor control device 100. 12, the same parts as those in FIG. 3 are denoted by the same reference numerals, and the description thereof is omitted. In the stepping motor control apparatus 100 of this embodiment, a paper feed driving roller 89 is connected to the paper feed drive shaft 67. In addition, the stepping motor control device 100 according to the present embodiment includes an integrated travel distance measurement unit 88 that is realized by the CPU 65 executing the program 86.

  The paper feed drive roller 89 is attached coaxially to the paper feed drive shaft 67. The gear ratio of the stepping motor shaft and the gears provided on the paper feed drive shaft 67 that mesh with each other is 1: 1.

The accumulated travel distance measuring unit 88 measures the accumulated travel distance of the paper feed drive roller 89.
FIG. 13 shows an example of a schematic perspective view of the paper feed drive roller 89. The locus of a certain point on the circumference of the paper feed drive roller 89 is integrated. Therefore, the accumulated travel distance measuring unit 88 calculates the accumulated travel distance from the following equation.
“Roller integrated travel distance (m)” = “motor rotational speed (rad / s)” × “feeding drive roller diameter r” × “motor integrated operating time (s)” (9)
In the formula (9), the “motor rotation speed (= roller rotation speed)” can be calculated from the formula (1), the “paper feed drive roller diameter r” is known, and the “motor integrated operation time” is the second embodiment. The re-update time elapsed measurement unit 87 measures.

  The accumulated travel distance measuring unit 88 sequentially adds the “roller accumulated travel distance” calculated by the equation (9) to the accumulated travel distance stored in the ROM 63. The accumulated travel distance measuring unit 88 stores “re-update distance” as a parameter (as part of the instruction code). For example, each time the main power supply of the image forming apparatus is turned on, the accumulated travel distance measurement unit 88 compares the renewal distance with the accumulated travel distance, and generates a table if the accumulated travel distance exceeds the reupdate distance. Request the part 81 to update the lookup table 84. When updated, the accumulated travel distance measuring unit 88 resets the accumulated travel distance.

  FIG. 14 is an example of a flowchart illustrating a procedure in which the stepping motor control device registers the coil current in the look-up table for motor efficiency and step-out presence / absence. The procedure in FIG. 14 starts, for example, every time the main power supply of the image forming apparatus is turned on.

  The accumulated travel distance measuring unit 88 determines whether or not the accumulated travel distance stored in the ROM 63 has reached the re-update distance (S410). If the accumulated travel distance has not reached the re-update distance (No in S410), the lookup table 84 is not updated, and the process in FIG. 14 ends.

  If the accumulated travel distance has reached the re-update distance (Yes in S410), the accumulated travel distance measurement unit 88 updates the lookup table 84 to the table generation unit 81 because it is the timing to update the lookup table 84. A request is made (S420).

  Thereby, the table generation unit 81 updates the lookup table 84 in the same manner as in the first embodiment (S330). The processing in step S330 is the same as steps S1 to S23 in FIG.

  According to the present embodiment, in addition to the effects of the first embodiment, the look-up table 84 is updated for each travel distance of the paper feed drive roller 89 that causes a change in load torque with time (such as gear wear). A highly efficient state can be maintained. In addition, the look-up table 84 is updated if the accumulated time is the same at the high rotation speed and the low rotation speed in the accumulated time of the second embodiment. In this embodiment, however, the actual travel distance of the paper feed drive roller 89 is updated. Therefore, the lookup table 84 can be updated at a more appropriate timing.

  In the second and third embodiments, the update timing of the lookup table 84 is determined from the operating state of the stepping motor 66. However, in this embodiment, the stepping motor control apparatus determines the update timing based on the continuous stop time of the stepping motor 66. 100 will be described.

  FIG. 15 is a diagram illustrating an example of a functional block diagram of the stepping motor control device 100. In FIG. 15, the same parts as those in FIG. The stepping motor control apparatus 100 according to the present embodiment includes a continuous stop time measuring unit 92 that is realized by the CPU 65 executing the program 86.

  The continuous stop time measuring unit 92 stores “stop determination time” as a parameter (as part of the instruction code). The continuous stop time measuring unit 92 measures the time during which the stepping motor 66 is continuously stopped.

  The continuous stop time measuring unit 92 overwrites and stores the date and time when the stepping motor 66 is stopped overwritten in the ROM 63 each time it is stopped. Therefore, the ROM 63 stores the date and time when the stepping motor 66 was last stopped. Then, the continuous stop time measuring unit 92 acquires the current date and time from the system control module. The system control module continuously holds the current date and time by the calendar function. The continuous stop time measuring unit 92 reads out from the ROM 63 whether or not the elapsed time from “the date and time when the stepping motor was last stopped” to “the current date and time” exceeds the stop determination time. Determine whether. If it exceeds, the continuous stop time measurement unit 92 requests the table generation unit 81 to update the lookup table 84.

  FIG. 16 is an example of a flowchart illustrating a procedure in which the stepping motor control device registers the coil current in the look-up table for motor efficiency and step-out presence / absence. The procedure in FIG. 16 starts, for example, every time the main power supply of the image forming apparatus is turned on.

  The continuous stop time measuring unit 92 determines whether or not the elapsed time from the “date and time when the stepping motor was last stopped” stored in the ROM 63 to the “current date and time” exceeds the stop determination time. Is determined (S510).

  If the elapsed time does not exceed the stop determination time (No in S510), the lookup table 84 is not updated, and the process in FIG. 16 ends.

  When the elapsed time exceeds the stop determination time (Yes in S510), it is the timing to update the lookup table 84, so the continuous stop time measurement unit 92 requests the table generation unit 81 to update the lookup table 84. (S520).

  Thereby, the table generation unit 81 updates the lookup table 84 in the same manner as in the first embodiment (S330). The processing in step S330 is the same as steps S1 to S23 in FIG.

  Further, the continuous stop time measuring unit 92 stores the date and time when the lookup table 84 is updated in the ROM 63 (S540).

  According to the present embodiment, in addition to the effects of the first embodiment, the lookup table 84 is updated even when the grease is hardened and the load torque changes with time because the stop time is long, so the motor efficiency is high. The state can be maintained. This embodiment can be combined with Embodiment 2 or 3.

  In this embodiment, a stepping motor control apparatus 100 that determines the update timing based on a change in temperature will be described. When the temperature changes, the viscosity of the grease changes, so that the motor efficiency may change. However, by updating the look-up table 84 based on the temperature change, it is possible to maintain a high motor efficiency state.

  FIG. 17 is a diagram illustrating an example of a functional block diagram of the stepping motor control device 100. In FIG. 17, the same parts as those of FIG. In the stepping motor control device 100 of this embodiment, a thermistor 91 is connected to the CPU 65. Further, the stepping motor control apparatus 100 of the present embodiment includes a temperature determination unit 93 that is realized by the CPU 65 executing the program 86.

  The thermistor 91 detects the ambient temperature in the apparatus and transmits it to the CPU 65 as an analog voltage signal. The temperature determination unit 93 A / D converts the analog electric signal and stores it in the ROM 63. In order to detect a change in temperature, the temperature determination unit 93 detects the current ambient temperature in the apparatus every predetermined time, and stores it in the ROM 63 in association with the date and time.

  The temperature determination unit 93 stores the ambient temperature when the lookup table 84 is updated in the ROM 63. Further, when the lookup table 84 is updated, for example, the date and time when the lookup table 84 is updated are clarified by the time stamp of the file information, and the date when the lookup table 84 is updated. The date and time are stored in the ROM 63 together with the lookup table 84. Therefore, the ambient temperature when the lookup table 84 is updated is also clarified from the date and time when the ambient temperature stored in the ROM 63 is measured.

  When the ambient temperature in the current device is significantly different from the ambient temperature when the lookup table 84 is updated (for example, 10 to 20 degrees), the temperature determination unit 93 updates the lookup table 84. A request is made to the generation unit 81.

  FIG. 18 is an example of a flowchart illustrating a procedure in which the stepping motor control device registers the coil current in the look-up table for motor efficiency and step-out presence / absence. The procedure of FIG. 18 starts, for example, every predetermined time (for example, every time the ambient temperature is measured) with the main power supply of the image forming apparatus turned on.

  The temperature determination unit 93 detects the current ambient temperature in the apparatus every predetermined time, and whether or not the difference from the “ambient temperature when the look-up table is updated” stored in the ROM 63 is changed to a threshold value or more. Is determined (S610).

  If the difference between the current ambient temperature and the ambient temperature when the lookup table 84 is updated is not equal to or greater than the threshold (No in S610), the lookup table 84 is not updated, and the process in FIG. 18 ends.

  If the difference between the current ambient temperature and the ambient temperature when the lookup table 84 is updated is equal to or greater than the threshold (Yes in S610), the lookup table 84 should be updated. The unit 81 is requested to update the lookup table 84 (S620).

  Thereby, the table generation unit 81 updates the lookup table 84 in the same manner as in the first embodiment (S330). The processing in step S330 is the same as steps S1 to S23 in FIG.

  Further, the temperature determination unit 93 stores the ambient temperature detected by the thermistor 91 when the lookup table 84 is updated in the ROM 63 (S640).

  According to the present embodiment, in addition to the effects of the first embodiment, even when the temperature changes and the viscosity of the grease changes, the look-up table 84 is updated, so that a high motor efficiency state can be maintained. In addition, a present Example can be combined with Examples 2-4.

  In the fifth embodiment, the update timing of the lookup table 84 is determined based on the temperature change. In this embodiment, the stepping motor control apparatus 100 that determines the update timing based on the change in humidity will be described. If the humidity changes, the motor efficiency may also change due to moisture absorption of the paper feed roller, etc., but by updating the look-up table 84 based on the change in humidity, a high motor efficiency state can be maintained.

  FIG. 19 is a diagram illustrating an example of a functional block diagram of the stepping motor control device 100. 19, the same parts as those in FIG. 3 are denoted by the same reference numerals, and the description thereof is omitted. In the stepping motor control device 100 of this embodiment, a hygrometer is connected to the CPU 65. In addition, the stepping motor control device 100 according to the present embodiment includes a humidity determination unit 95 that is realized by the CPU 65 executing the program 86.

  The humidity sensor 94 detects the ambient humidity in the apparatus and transmits it to the CPU 65 as an analog voltage signal. The humidity determination unit 95 A / D converts the analog electric signal and stores it in the ROM 63. In order to detect a change in humidity, the humidity determination unit 95 detects the ambient humidity in the current apparatus every predetermined time, and stores it in the ROM 63 in association with the date and time.

  The humidity determination unit 95 stores the ambient humidity when the lookup table 84 is updated in the ROM 63. Therefore, the ambient humidity when the lookup table 84 is updated is also clarified.

  When the ambient humidity in the current device is greatly different from the ambient humidity when the lookup table 84 is updated (for example, 10 to 20%), the humidity determination unit 95 updates the lookup table 84. A request is made to the generation unit 81.

  FIG. 20 is an example of a flowchart illustrating a procedure in which the stepping motor control device registers the coil current in the look-up table for motor efficiency and step-out presence / absence. The procedure in FIG. 20 starts, for example, every predetermined time (for example, every time ambient humidity is measured) in a state where the main power supply of the image forming apparatus is ON.

  The humidity determination unit 95 detects the ambient humidity in the current apparatus every predetermined time, and whether or not the difference from the “ambient humidity when the look-up table is updated” stored in the ROM 63 is changed to a threshold value or more. Is determined (S710).

  When the difference between the current ambient humidity and the ambient humidity when the lookup table 84 is updated is not equal to or greater than the threshold (No in S710), the lookup table 84 is not updated, and the processing in FIG. 20 ends.

  If the difference between the current ambient humidity and the ambient humidity when the lookup table 84 is updated is equal to or greater than the threshold (Yes in S710), the lookup table 84 should be updated. The update request of the lookup table 84 is requested to the part 81 (S720).

  Thereby, the table generation unit 81 updates the lookup table 84 in the same manner as in the first embodiment (S330). The processing in step S330 is the same as steps S1 to S23 in FIG.

  The humidity determination unit 95 stores the ambient humidity detected by the humidity sensor 94 when the lookup table 84 is updated in the ROM 63 (S740).

  According to the present embodiment, in addition to the effects of the first embodiment, even if the humidity changes and the motor efficiency changes due to moisture absorption by the paper feed roller or the like, the look-up table 84 is updated, so that a high motor efficiency state is maintained. be able to. In addition, a present Example can be combined with Examples 2-5.

  In the first to sixth embodiments, the lookup table is generated in the image forming apparatus 200, but the lookup table may be generated by an external computer. Explaining using FIG. 3 as an example, a computer is connected via the USB I / F 71. Then, the computer has the table generation unit 81 and the function information 85 or receives the program 86 and the function information 85 for realizing the table generation unit 81 from the image forming apparatus 200. By doing so, the computer can provide a function equivalent to that of the table generating unit 81.

  Since the computer can receive the motor rotation speed and the motor load torque via the USB I / F 71, the computer can read the ROM 63 from the “motor rotation speed” detected by the rotary encoder 69 and the “load torque” detected by the torque sensor 68. The “motor output” is calculated using the function information 85 stored in. In addition, this computer calculates “power consumption” from the “power supply voltage” and “power supply current” detected by the power supply voltage / current detection circuit 62 using the function information 85. Then, the computer calculates “motor efficiency” using the function information 85 from the calculated “motor output” and “power consumption”. The table generation unit 81 of the computer generates a lookup table 84 in which “pulse frequency (PPS)”, “coil current”, and “motor efficiency” are associated.

  In addition, the step-out presence / absence determining unit 81b of the computer sets the “motor rotation speed” to the target motor rotation speed even after a predetermined time has elapsed after the drive of the paper feed motor is started by the pulse current and the coil current as the target PPS. If not reached, it is determined that step-out has occurred. The table generation unit 81 of the computer registers “0 (%)” in the column of “motor efficiency” of the lookup table 84 and “1 (out of step)” in the column of “out of step”.

  In this manner, an external computer can also generate the lookup table 84. The computer transmits the generated lookup table 84 to the image forming apparatus 200 via the USB I / F 71. The image forming apparatus 200 stores the received lookup table 84 in the ROM 63.

  Therefore, the look-up table 84 does not need to be generated in the image forming apparatus 200. By registering the externally generated look-up table 84 in the image forming apparatus 200, even if the load torque is relatively low, the step-out table 84 is not generated. The stepping motor can be driven with the most efficient coil current.

  The external computer includes an integrated operation time of the stepping motor 66, an integrated travel distance of the drive transmission unit of the stepping motor 66, an elapsed time since the last stop of the stepping motor 66, an ambient temperature of the stepping motor 66, Alternatively, the humidity around the stepping motor 66 can be acquired from the image forming apparatus 200. Therefore, as described in the second to sixth embodiments, it is possible to determine the update timing from these and generate the lookup table 84.

61 Power supply 62 Power supply voltage / current detection circuit 63 ROM
64 Motor driver 65 CPU
66 Stepping Motor 67 Paper Feed Drive Shaft 68 Torque Sensor 69 Rotary Encoder 72 Storage Medium 81 Table Generation Unit 82 Coil Current Selection Unit 83 Motor Drive Unit 84 Lookup Table 85 Function Information 86 Program 100 Stepping Motor Control Device 200 Image Forming Device

Japanese Patent Laid-Open No. 11-215890 Japanese Patent Laid-Open No. 11-146695

Claims (10)

A stepping motor control device that outputs coil current value information and pulse frequency information to a stepping motor drive circuit,
Motor efficiency determining means for determining the motor efficiency of the stepping motor by changing a coil current value for one pulse frequency; and step-out presence / absence determining means for determining whether or not the stepping motor is out of step;
Table generation means for generating a table in which motor efficiency information and step-out presence / absence are registered in association with pulse frequency information and coil current value information;
Selection means for selecting, from the table, coil current value information having no step-out and having the highest motor efficiency among a plurality of pieces of coil current value information associated with one pulse frequency information based on the rotation speed of the stepping motor; ,
A stepping motor control device comprising: control information output means for outputting the coil current value information selected by the selection means to the drive circuit. A stepping motor control device for outputting coil current value information and pulse frequency information registered in a table to a stepping motor drive circuit,
Motor efficiency determining means for determining the motor efficiency of the stepping motor by changing a coil current value for one pulse frequency; and step-out presence / absence determining means for determining whether or not the stepping motor is out of step;
Corresponding to pulse frequency information and coil current value information, motor efficiency information and table generation means for generating the table in which step-out presence / absence is registered , from an external device having
Table acquisition means for acquiring the table;
Table storage means for storing the table;
Selection means for selecting, from the table, coil current value information having no step-out and having the highest motor efficiency among a plurality of pieces of coil current value information associated with one pulse frequency information based on the rotation speed of the stepping motor; ,
A stepping motor control device comprising: control information output means for outputting the coil current value information selected by the selection means to the drive circuit. In the table, a plurality of the coil current value information are associated in descending order with respect to one pulse frequency information sorted in ascending order,
When the step-out presence / absence determining means determines the step-out presence / absence of the stepping motor in descending order of the coil current value information, the step-out presence / absence determining means is a coil smaller than the coil current value information determined to have stepped out. Without judging the current value information step-out,
The table generation unit registers step-out presence in association with coil current value information smaller than the coil current value information determined to have step-out.
The stepping motor control device according to claim 1 or 2, wherein The selection means selects the smallest coil current value information when a plurality of coil current value information with no step-out and the highest motor efficiency is registered in one pulse frequency information of the table.
The stepping motor control device according to any one of claims 1 to 3, wherein Measuring means for measuring the cumulative operating time of the stepping motor;
Triggered by the cumulative operating time exceeding a threshold,
The table generating means starts updating the table;
The stepping motor control device according to any one of claims 1 to 4, wherein the stepping motor control device is provided. The stepping motor has a measuring means for measuring an accumulated travel distance of a drive transmission unit that rotationally drives the rotated member,
Triggered by the cumulative mileage exceeding a threshold,
The table generating means starts updating the table;
The stepping motor control device according to any one of claims 1 to 4, wherein the stepping motor control device is provided. Measuring means for measuring an elapsed time since the stepping motor stopped immediately before,
Triggered when the elapsed time exceeds a threshold,
The table generating means starts updating the table;
The stepping motor control device according to any one of claims 1 to 4, wherein the stepping motor control device is provided. Temperature detecting means for detecting the ambient temperature of the stepping motor;
Determining means for determining whether or not the ambient temperature exceeds a threshold;
Triggered by the ambient temperature exceeding a threshold,
The table generating means starts updating the table;
The stepping motor control device according to any one of claims 1 to 4, wherein the stepping motor control device is provided. Humidity detecting means for detecting the humidity around the stepping motor;
Determination means for determining whether the ambient humidity exceeds a threshold value,
Triggered by the ambient humidity exceeding a threshold,
The table generating means starts updating the table;
The stepping motor control device according to any one of claims 1 to 4, wherein the stepping motor control device is provided. An information processing device outputs a coil current value information and pulse frequency information to a stepping motor drive circuit to control rotation of the stepping motor,
Changing the coil current value for one pulse frequency to determine the motor efficiency of the stepping motor; determining whether or not the stepping motor is out of step;
Associating the pulse frequency information with the coil current value information, generating a table in which the motor efficiency information and the presence or absence of step-out are registered;
A selection step of selecting, from the table, coil current value information having no step-out and having the highest motor efficiency among a plurality of coil current value information associated with pulse frequency information based on the rotation speed of the stepping motor;
And outputting the coil current value information selected in the selection step to the drive circuit.

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