JP3900401B2 - DC motor control method and control apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a DC motor control method and a control apparatus, and in particular, an abnormal noise generated at the meshing position of the gear when the DC motor is started due to backlash of the gear of the DC motor and cogging torque of the DC motor. The present invention relates to a DC motor control method and a control apparatus for preventing this. The present invention also relates to a recording medium on which a computer program for executing the DC motor control method is recorded.
[0002]
[Prior art]
First, a schematic configuration and control method of an ink jet printer using a DC motor control device will be described.
[0003]
FIG. 2 is a block diagram showing a schematic configuration of the ink jet printer.
[0004]
The ink jet printer shown in FIG. 2 ejects ink onto a paper feed motor (hereinafter also referred to as PF motor) 1 that feeds paper, a paper feed motor driver 2 that drives the paper feed motor 1, and printing paper 50. The head 9 is fixed, the carriage 3 is driven in a direction parallel to the printing paper 50 and perpendicular to the paper feeding direction, a carriage motor (hereinafter also referred to as a CR motor) 4 for driving the carriage 3, and a carriage motor. 4, a DC motor 6 that delivers a direct current command value to the CR motor driver 5, a pump motor 7 that controls the suction of ink to prevent clogging of the head 9, and a pump motor 7 Motor driver 8 for driving the head, head driver 10 for driving and controlling the head 9, and linear type fixed to the carriage 3 A encoder 11, a code plate 12 for a linear encoder 11 having slits formed at predetermined intervals, a rotary encoder 13 for the PF motor 1, and a paper detection sensor 15 for detecting the end position of the paper being printed. A CPU 16 that controls the entire printer, a timer IC 17 that periodically generates an interrupt signal to the CPU 16, and an interface unit (hereinafter also referred to as IF) 19 that transmits and receives data to and from the host computer 18. The ASIC 20 for controlling the print resolution, the drive waveform of the head 9 and the like based on the print information sent from the host computer 18 through the IF 19, and the PROM 21 and RAM 22 used as work areas and program storage areas of the ASIC 20 and the CPU 16. And the EEPROM 23 and the plastic paper 50 supporting the printing paper 50 25, a transport roller 27 that is driven by the PF motor 1 to transport the printing paper 50, a pulley 30 that is attached to the rotating shaft of the CR motor 4, and a timing belt 31 that is driven by the pulley 30. Yes.
[0005]
The DC unit 6 drives and controls the paper feed motor driver 2 and the CR motor driver 5 based on the control command sent from the CPU 16 and the outputs of the encoders 11 and 13. Further, both the paper feed motor 1 and the CR motor 4 are constituted by DC motors.
[0006]
FIG. 3 is a perspective view showing a configuration around the carriage 3 of the ink jet printer.
[0007]
As shown in FIG. 3, the carriage 3 is connected to the carriage motor 4 via the pulley 30 by the timing belt 31, and is driven so as to move parallel to the platen 25 while being guided by the guide member 32. A recording head 9 having a nozzle row for ejecting black ink and a nozzle row for ejecting color ink is provided on the surface of the carriage 3 facing the printing paper, and each nozzle is supplied with ink from the ink cartridge 34 for printing. Characters and images are printed by ejecting ink droplets on paper.
[0008]
Further, in the non-printing area of the carriage 3, a capping device 35 for sealing the nozzle openings of the recording head 9 at the time of non-printing and a pump unit 36 having the pump motor 7 shown in FIG. 2 are provided. . When the carriage 3 moves from the printing area to the non-printing area, the carriage 3 comes into contact with a lever (not shown), the capping device 35 moves upward, and the head 9 is sealed.
[0009]
When the nozzle opening row of the head 9 is clogged or when the ink is forcibly ejected from the head 9 by replacing the cartridge 34 or the like, the pump unit 36 is operated with the head 9 sealed. The ink is sucked out from the nozzle opening row by the negative pressure from the pump unit 36. As a result, dust and paper dust adhering to the vicinity of the nozzle opening row are washed, and air bubbles in the head 9 are discharged to the cap 37 together with ink.
[0010]
FIG. 4 is an explanatory diagram schematically showing the configuration of the linear encoder 11 attached to the carriage 3.
[0011]
The encoder 11 shown in FIG. 4 includes a light emitting diode 11a, a collimator lens 11b, and a detection processing unit 11c. The detection processing unit 11c includes a plurality (four) of photodiodes 11d, a signal processing circuit 11e, and two comparators 11fA and 11fB.
[0012]
When the voltage VCC is applied across the light emitting diode 11a via a resistor, light is emitted from the light emitting diode 11a. This light is condensed into parallel light by the collimator lens 11 b and passes through the code plate 12. The code plate 12 is provided with slits at predetermined intervals (for example, 1/180 inch (1 inch = 2.54 cm)).
[0013]
The parallel light that has passed through the code plate 12 enters each photodiode 11d through a fixed slit (not shown) and is converted into an electrical signal. The electric signals output from the four photodiodes 11d are processed in the signal processing circuit 11e, the signals output from the signal processing circuit 11e are compared in the comparators 11fA and 11fB, and the comparison result is output as a pulse. Pulses ENC-A and ENC-B output from the comparators 11fA and 11fB are output from the encoder 11.
[0014]
FIG. 5 is a timing chart showing waveforms of two output signals of the encoder 11 at the time of forward rotation and reverse rotation of the CR motor.
[0015]
As shown in FIGS. 5A and 5B, the phase of the pulse ENC-A and the pulse ENC-B differ by 90 degrees in both cases of the CR motor forward rotation and reverse rotation. When the CR motor 4 is rotating forward, that is, when the carriage 3 is moving in the main scanning direction, the pulse ENC-A is 90 degrees from the pulse ENC-B, as shown in FIG. When the phase is advanced only by the time and the CR motor 4 is reversely rotated, the encoder 4 is configured so that the phase of the pulse ENC-A is delayed by 90 degrees from the pulse ENC-B, as shown in FIG. ing. One period T of the pulse corresponds to the slit interval (for example, 1/180 inch) of the code plate 12, and is equal to the time for the carriage 3 to move the slit interval.
[0016]
On the other hand, the rotary encoder 13 for the PF motor 1 has the same configuration as that of the linear encoder 11 except that the code plate is a rotating disc that rotates in accordance with the rotation of the PF motor 1, and has two output pulses. ENC-A and ENC-B are output. In the ink jet printer, the slit interval of the plurality of slits provided on the code plate of the rotary encoder 13 for the PF motor 1 is 1/180 inch, and when the PF motor 1 rotates by the 1 slit interval, 1 / The paper is fed by 1440 inches.
[0017]
FIG. 6 is a perspective view showing portions related to paper feeding and paper detection.
The position of the paper detection sensor 15 shown in FIG. 2 will be described with reference to FIG. In FIG. 6, the printing paper 50 inserted into the paper feed insertion slot 61 of the printer 60 is fed into the printer 60 by a paper feed roller 64 driven by a paper feed motor 63. The leading edge of the printing paper 50 fed into the printer 60 is detected by, for example, the optical paper detection sensor 15. The paper 50 whose leading edge is detected by the paper detection sensor 15 is fed by the paper feed roller 65 and the driven roller 66 driven by the PF motor 1.
[0018]
Subsequently, printing is performed by dropping ink from a recording head (not shown) fixed to the carriage 3 that moves along the carriage guide member 32. When the paper is fed to a predetermined position, the end of the currently printed printing paper 50 is detected by the paper detection sensor 15. The printed paper 50 that has been printed is discharged from the paper discharge port 62 to the outside by the paper discharge roller 68 and the driven roller 69 driven by the gear 67C via the gears 67A and 67B driven by the PF motor 1. A rotary encoder 13 is connected to the rotation shaft of the paper feed roller 65.
[0019]
Next, a configuration of a DC unit 6 that is a conventional DC motor control device that controls the CR motor 4 of the above-described inkjet printer, and a control method by the DC unit 6 will be described.
[0020]
FIG. 7 is a block diagram showing the configuration of a DC unit 6 that is a conventional DC motor control device, and FIG. 8 is a graph showing the motor current and motor speed of the CR motor 4 controlled by the DC unit 6. is there.
[0021]
The DC unit 6 shown in FIG. 7 includes a position calculator 6a, a subtractor 6b, a target speed calculator 6c, a speed calculator 6d, a subtractor 6e, a proportional element 6f, an integral element 6g, a differential It comprises an element 6h, an adder 6i, a D / A converter 6j, a timer 6k, and an acceleration controller 6m.
[0022]
The position calculator 6a detects the rising edge and the falling edge of each of the output pulses ENC-A and ENC-B of the encoder 11, counts the number of detected edges, and based on the counted value, the carriage 3 The position of is calculated. This count is incremented by “+1” when one edge is detected when the CR motor 4 is rotating in the forward direction, and “−1” when one edge is detected when the CR motor 4 is rotating in the reverse direction. Is added. The period of each of the pulses ENC-A and ENC-B is equal to the slit interval of the code plate 12, and the phase of the pulse ENC-A and the pulse ENC-B differ by 90 degrees. Therefore, the count value “1” of the count corresponds to ¼ of the slit interval of the code plate 12. Thus, if the count value is multiplied by 1/4 of the slit interval, the amount of movement from the position of the carriage 3 corresponding to the count value “0” can be obtained. At this time, the resolution of the encoder 11 is ¼ of the interval between the slits of the code plate 12. If the interval between the slits is 1/180 inch, the resolution is 1/720 inch.
[0023]
The subtractor 6b calculates a position deviation between the target position sent from the CPU 16 and the actual position of the carriage 3 obtained by the position calculation unit 6a.
[0024]
The target speed calculator 6c calculates the target speed of the carriage 3 based on the position deviation that is the output of the subtractor 6b. This calculation is performed by multiplying the position deviation by the gain KP. This gain KP is determined according to the position deviation. Note that the value of the gain KP may be stored in a table (not shown).
[0025]
The speed calculator 6 d calculates the speed of the carriage 3 based on the output pulses ENC-A and ENC-B of the encoder 11. This speed is obtained as follows. First, the rising edge and the falling edge of each of the output pulses ENC-A and ENC-B of the encoder 11 are detected, and the time interval between edges corresponding to 1/4 of the slit interval of the code plate 12 is determined by a timer counter. Count. If this count value is T and the slit interval of the code plate 12 is λ, the carriage speed can be obtained as λ / (4T). Here, the calculation of the speed is obtained by measuring one cycle of the output pulse ENC-A, for example, from the rising edge to the next rising edge with a timer counter.
[0026]
The subtractor 6e calculates a speed deviation between the target speed and the actual speed of the carriage 3 calculated by the speed calculation unit 6d.
[0027]
The proportional element 6f multiplies the speed deviation by a constant Gp and outputs the multiplication result. The integration element 6g integrates the speed deviation multiplied by a constant Gi. The differentiation element 6h multiplies the difference between the current speed deviation and the previous speed deviation by a constant Gd, and outputs the multiplication result. The calculation of the proportional element 6f, the integral element 6g, and the derivative element 6h is performed in synchronization with the rising edge of the output pulse ENC-A, for example, for each cycle of the output pulse ENC-A of the encoder 11.
[0028]
The outputs of the proportional element 6f, the integral element 6g, and the derivative element 6h are added by the adder 6i. Then, the addition result, that is, the driving current of the CR motor 4 is sent to the D / A converter 6j and converted into an analog current. The CR motor 4 is driven by the driver 5 based on the analog voltage.
[0029]
The timer 6k and the acceleration control unit 6m are used for acceleration control, and the PID control using the proportional element 6f, the integral element 6g, and the derivative element 6h is used for constant speed and deceleration control during acceleration.
[0030]
The timer 6k generates a timer interrupt signal every predetermined time based on the clock signal sent from the CPU 16.
[0031]
Each time the acceleration control unit 6m receives the timer interrupt signal, the acceleration control unit 6m integrates a predetermined current value (for example, 20 mA) to the target current value, and the integration result, that is, the target current value of the DC motor 4 during acceleration is D / A is sent to the A converter 6j. As in the case of PID control, the target current value is converted into an analog current by the D / A converter 6j, and the CR motor 4 is driven by the driver 5 based on this analog current.
[0032]
The driver 5 includes, for example, four transistors, and (a) an operation mode in which the CR motor 4 is rotated forward or reverse by turning each of the transistors on or off based on the output of the D / A converter 6j. b) Regenerative brake operation mode (short brake operation mode, i.e., mode in which the CR motor is stopped) and (c) mode in which the CR motor is to be stopped can be performed.
[0033]
Next, the operation of the DC unit 6, that is, a conventional DC motor control method will be described with reference to FIGS.
[0034]
When the start command signal for starting the CR motor 4 is sent from the CPU 16 to the DC unit 6 when the CR motor 4 is stopped, the start initial current value I0 is sent from the acceleration control unit 6m to the D / A converter 6j. It is done. This starting initial current value I0 is sent from the CPU 16 to the acceleration control unit 6m together with the starting command signal. The current value I0 is converted to an analog voltage by the D / A converter 6j and sent to the driver 5, and the CR motor 4 starts to be started by the driver 5 (see FIGS. 8A and 8B). After receiving the start command signal, a timer interrupt signal is generated from the timer 6k every predetermined time. Each time the acceleration control unit 6m receives a timer interrupt signal, the acceleration control unit 6m adds a predetermined current value (for example, 20 mA) to the startup initial current value I0, and sends the integrated current value to the D / A converter 6j. Then, the integrated current value is converted into an analog current by the D / A converter 6j and sent to the driver 5. Then, the CR motor is driven by the driver 5 and the speed of the CR motor 4 is increased so that the value of the current supplied to the CR motor 4 becomes the integrated current value (see FIG. 8B). For this reason, the current value supplied to the CR motor 4 is stepped as shown in FIG. At this time, the PID control system is also operating, but the D / A converter 6j selects and takes in the output of the acceleration control unit 6m.
[0035]
The integration process of the current value of the acceleration control unit 6m is performed until the integrated current value becomes a constant current value IS. When the current value integrated at time t1 reaches a predetermined value IS, the acceleration control unit 6m stops the integration process and supplies a constant current value IS to the D / A converter 6j. Thus, the driver 5 is driven so that the value of the current supplied to the CR motor 4 becomes the current value IS (see FIG. 8A).
[0036]
In order to prevent the speed of the CR motor 4 from overshooting, when the CR motor 4 reaches a predetermined speed V1 (see time t2), acceleration control is performed so as to reduce the current supplied to the CR motor 4. The unit 6m controls. At this time, the speed of the CR motor 4 further increases, but when the speed of the CR motor 4 reaches a predetermined speed Vc (see time t3 in FIG. 8B), the D / A converter 6j outputs the output of the PID control system. That is, the output of the adder 6i is selected and PID control is performed.
[0037]
That is, the target speed is calculated based on the position deviation between the target position and the actual position obtained from the output of the encoder 11, and based on the speed deviation between the target speed and the actual speed obtained from the output of the encoder 11. Thus, the proportional element 6f, the integral element 6g, and the differential element 6h operate to perform proportional, integral, and differential calculations, respectively, and the CR motor 4 is controlled based on the sum of these calculation results. The proportional, integral and differential calculations are performed in synchronization with the rising edge of the output pulse ENC-A of the encoder 11, for example. As a result, the speed of the DC motor 4 is controlled to a desired speed Ve. The predetermined speed Vc is preferably 70 to 80% of the desired speed Ve.
[0038]
Since the DC motor 4 has a desired speed from time t4, the carriage 3 also has a desired constant speed Ve, and printing processing can be performed.
[0039]
When the printing process is completed and the carriage 3 approaches the target position (see time t5 in FIG. 8B), the position deviation becomes small and the target speed also becomes small. Therefore, the speed deviation, that is, the output of the subtractor 6e is obtained. It becomes negative, the DC motor 4 is decelerated, and stops at time t6.
[0040]
[Problems to be solved by the invention]
However, in the above-described conventional DC motor control method and control device, abnormal noise is generated at the meshing position of the gear when starting the DC motor due to the backlash of the DC motor gear and the cogging torque of the DC motor. There was a problem of doing. The specific contents of the problem will be described below.
[0041]
First, the cogging torque of the DC motor and the backlash of the gear of the DC motor, which are one cause of this problem, will be described.
[0042]
FIG. 11 is a graph showing the relationship between the absolute value of the cogging torque of the DC motor and the phase of the armature (rotor).
[0043]
The magnitude (absolute value) of the cogging torque of the DC motor varies periodically according to the phase of the rotor of the DC motor, as shown in FIG. It becomes a stable point. At the stable point, neither forward direction torque nor reverse direction torque is generated in the rotor.
[0044]
However, the position becomes unstable at a position other than the stable point, and a torque is generated to move to the stable point. At a position where the gradient of the graph is negative, for example, at point P1, forward rotation direction torque is generated in the rotor, and at a position where the gradient of the graph is positive, such as at point P2, reverse rotation direction torque is generated in the rotor.
[0045]
FIG. 12 is an explanatory view schematically showing the state of gear backlash. The gear G1 is a gear coupled to the shaft of the rotor, and the gear G2 is a gear that is rotationally driven by the gear G1.
[0046]
FIG. 12A shows a state when the motor is stopped in the forward rotation direction. When the motor stops driving in the forward direction, the tooth C1 of the gear G1 and the tooth C2 of the gear G2 are in contact with each other.
[0047]
By the way, a backlash (play) is usually provided between one tooth and the other tooth of two gears meshed with each other in terms of mechanism design.
[0048]
However, when the DC current supply for driving the motor in the forward direction is stopped and the cogging torque generated at the position where the rotor is stopped is the torque at the point P2 in FIG. Torque is generated. And since the backlash is provided in meshing | engagement with the gear G1 and the gear G2, the phenomenon in which the gear G1 reversely rotates within the range which backlash accept | permits generate | occur | produces.
[0049]
As a result, as shown in FIG. 12B, a gap D is generated between the tooth C1 of the gear G1 and the tooth C2 of the gear G2. From this state, when the normal rotation direction drive of the motor is started again and normal acceleration control is performed, the tooth C1 of the gear G1 strongly hits the tooth C2 of the gear G2, and an abnormal noise “click” is generated. End up. In particular, a printer used in an office or a private home is required to be quiet in operation, but such abnormal noise has been a problem because it disturbs the quietness.
[0050]
Even if the position where the rotor of the DC motor is stopped is just a stable point and no cogging torque is generated in the forward or reverse direction, the motor drive directions before and after the stop are opposite to each other. In such a case, due to the backlash of the gear, the same problem as described above occurs when the drive is started after the stop.
[0051]
FIG. 13 is a graph showing in detail the motor current when the motor is driven in the forward direction in the conventional DC motor control method and control apparatus. A period TX in FIG. 13 is an acceleration control section, and a period TY is a PID control section. Here, in particular, the control at the start of the acceleration control in the period TX will be described in detail.
[0052]
The current Ith shown on the vertical axis of the graph of FIG. 13 is a minimum current value required for the gear G1 in FIG. 12 to rotationally drive the gear G2. That is, the current Ith is a threshold current for the gear coupled to the rotor shaft to rotationally drive another meshed gear.
[0053]
In the conventional DC motor control method and control device, the initial value I1 of the direct current supplied to the motor is set to a value equal to or greater than the threshold current Ith when acceleration control is started in the period TX, that is, when the motor is driven in the forward direction. It was.
[0054]
Therefore, due to the backlash of the gear of the DC motor and the cogging torque of the DC motor, the gap D is formed between the tooth C1 of the gear G1 and the tooth C2 of the gear G2, as shown in FIG. If it occurs, the tooth C1 of the gear G1 strongly hits the tooth C2 of the gear G2, and there is a problem that an abnormal noise “click” occurs.
[0055]
The present invention has been made in view of the above-described problems, and the object thereof is generated at the meshing position of the gear when the DC motor is started due to the backlash of the gear of the DC motor and the cogging torque of the DC motor. To provide a DC motor control method and a control device for preventing abnormal noise.
[0056]
[Means for Solving the Problems]
According to the DC motor control method of the present invention, the first gear coupled to the rotor shaft of the DC motor is required for rotationally driving the second gear meshed with the first gear. DC current having a value less than a threshold current, which is a value that can rotate the first gear itself as an initial value current, for a predetermined period when the DC motor is started. It supplies to the said DC motor, It is characterized by the above-mentioned. With this configuration, it is possible to prevent the generation of abnormal noise due to the backlash of the DC motor gear, the cogging torque of the DC motor, and the like when the motor drive is started.
[0057]
According to the DC motor control device of the present invention, the first gear coupled to the rotor shaft of the DC motor is required for rotationally driving the second gear meshed with the first gear. DC current having a value less than a threshold current, which is a value that can rotate the first gear itself as an initial value current, for a predetermined period when the DC motor is started. An initial value current supply command unit that generates and outputs an initial value current supply command signal for instructing supply to the DC motor is provided. With this configuration, it is possible to prevent the generation of abnormal noise due to the backlash of the DC motor gear, the cogging torque of the DC motor, and the like when the motor drive is started.
[0059]
The predetermined period is a time necessary and sufficient for the teeth of the first gear to abut against the teeth of the second gear in the direction in which the first gear drives the second gear. It may be set based on the value of the initial value current.
[0060]
The DC motor may be any one of a paper feed motor, a carriage motor, and a paper feed motor of the printer.
[0061]
According to the computer program recording medium of the present invention, a computer program for executing any one of the DC motor control methods according to the present invention in a computer system is recorded.
[0062]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of a DC motor control method and control apparatus according to the invention and a recording medium on which a computer program for executing the DC motor control method is recorded will be described with reference to the drawings.
[0063]
FIG. 1 is a graph showing in detail the motor current when the motor is driven in the forward direction in the DC motor control method and control apparatus according to the present invention. FIG. 1 corresponds to FIG. 13 of the prior art, and similarly to FIG. 13, the period TX is an acceleration control section and the period TY is a PID control section. This control will be described in detail.
[0064]
The current Ith shown on the vertical axis of the graph of FIG. 1 is the minimum current value required for the gear G1 in FIG. 12 to rotationally drive the gear G2, as in FIG. That is, the current Ith is a threshold current for the gear coupled to the rotor shaft to rotationally drive another meshed gear.
[0065]
As described above, in the conventional DC motor control method and control device, the initial value I1 of the direct current supplied to the motor is a value equal to or greater than the threshold current Ith at the start of acceleration control in the period TX, that is, at the start of motor drive. Therefore, there has been a problem that abnormal noise is generated due to the backlash of the gear of the DC motor and the cogging torque of the DC motor.
[0066]
Therefore, in the DC motor control method and control apparatus according to the present invention, as shown in the graph of FIG. 1, the initial value of the direct current supplied to the motor at the start of acceleration control in the period TX, that is, at the start of motor drive. I0 is set to a value less than the threshold current Ith. This is the most characteristic point of the DC motor control method and control device according to the present invention.
[0067]
The principle by which the problems of the prior art are solved by the DC motor control method and control device according to the present invention will be described with reference to FIGS.
[0068]
Assuming that the initial value I0 of the direct current supplied to the motor at the start of the motor drive is a value less than the threshold current Ith, the gear G1 coupled to the rotor shaft while the initial value current I0 is supplied from the start of the start. However, the other meshed gear G2 cannot be rotationally driven. However, the initial value current I0 is set to a current value at which the gear G1 itself can rotate unless the other gear is engaged with the gear G1.
[0069]
Therefore, even if the gear G2 is engaged with the gear G1, due to the backlash of the gear of the DC motor, the cogging torque, and other causes, as shown in FIG. 12B, the teeth C1 of the gear G1 and the gear G2 When the gap D is generated between the gear C1 and the tooth C2, when the initial current I0 is supplied to the motor, the gear G1 rotates until the tooth C1 of the gear G1 contacts the tooth C2 of the gear G2. be able to. Since the supply current at this time is an initial value current I0 which is a minute current less than the threshold current Ith, the tooth C1 of the gear G1 comes into contact with the tooth C2 of the gear G2. That is, since the tooth C1 of the gear G1 does not hit the tooth C2 of the gear G2 strongly, it is possible to prevent the occurrence of an abnormal noise such as “click”.
[0070]
Therefore, the initial value current I0 in the DC motor control method and control device according to the present invention is, in other words, the tooth of the gear G1 coupled to the shaft of the rotor of the DC motor and the tooth of the gear G2 meshed with the gear G1. It can be said that the direct current is smaller than the direct current of a magnitude that generates a striking sound when it comes into contact with.
[0071]
The period during which the initial value current I0 is supplied from the start of startup is the first period TX0 of the period TX that is the acceleration control period. The length of the period TX0 is that the tooth C1 of the gear G1 contacts the tooth C2 of the gear G2 even when the gap D generated between the tooth C1 of the gear G1 and the tooth C2 of the gear G2 is the maximum value. The necessary and sufficient time is appropriately set based on the initial value I0.
[0072]
After the elapse of the period TX0, the process proceeds to the remaining period TX1 of the period TX, and normal acceleration control is performed. For example, a direct current I1 that is equal to or greater than the threshold current Ith is supplied for a period Ti, and then the supply current is increased by a predetermined value Ii each time the period Ti elapses. Further, after all the periods TX have elapsed, the period shifts to the period TY, and normal PID control is performed.
[0073]
The hardware configuration of the DC motor control device according to the present invention is substantially the same as the configuration of the DC unit 6 which is a conventional DC motor control device. However, the DC motor control device according to the present invention is as described above. The difference is that the initial value current supply is set.
[0074]
In the acceleration control unit 6m shown in FIG. 7, the DC motor control apparatus according to the present invention generates the initial value current I0 for the period TX0 set based on the initial value current I0 as described above when the motor drive is started. In this configuration, an initial value current supply command signal for instructing supply is generated and output. The period TX0 is measured based on the timer interrupt signal from the timer 6k.
[0075]
This initial value current supply command signal is sent to the D / A converter 6j and converted into an analog current, and the DC motor (CR motor) 4 is driven by the driver 5 based on the analog current.
[0076]
When the DC motor control method and control apparatus according to the present invention are applied to a printer, the DC motor to be controlled is a paper feed motor that feeds out recording paper loaded in the printer, and a paper feed motor that feeds paper during printing Or a carriage motor for driving the carriage.
[0077]
Further, the DC motor control method and control device according to the present invention can be applied both when the motor is driven in the forward direction driving and when the motor is driven in the reverse direction driving.
[0078]
FIG. 9 is an explanatory diagram showing the external configuration of a recording medium on which a computer program for executing the DC motor control method according to the present invention is recorded and a computer system in which the recording medium is used, and FIG. 10 is shown in FIG. It is a block diagram showing a configuration of a computer system.
A computer system 70 shown in FIG. 9 includes a computer main body 71 housed in a mini-tower type housing, a display device 72 such as a CRT (Cathode Ray Tube), a plasma display, and a liquid crystal display device, and a recording device. It comprises a printer 73 as an output device, a keyboard 74a and a mouse 74b as input devices, a flexible disk drive device 76, and a CD-ROM drive device 77. FIG. 10 shows the configuration of the computer system 70 as a block diagram. Inside the housing in which the computer main body 71 is housed, an internal memory 75 such as a RAM (Random Access Memory), a hard disk drive unit 78, and the like. An external memory is further provided. A recording medium on which a computer program for executing the motor control method according to the present invention is recorded is used in the computer system 70. As the recording medium, for example, a flexible disk 81 and a CD-ROM (Read Only Memory) 82 are used. In addition, an MO (Magneto Optical) disk, a DVD (Digital Versatile Disk), other optical recording disks, and a card memory. Alternatively, a magnetic tape or the like may be used.
[0079]
【The invention's effect】
According to the DC motor control method of the present invention, the first gear coupled to the rotor shaft of the DC motor is required for rotationally driving the second gear meshed with the first gear. DC current having a value less than a threshold current, which is a value that can rotate and drive the first gear itself, is used as an initial value current, and the DC current is applied only for a predetermined period when the DC motor is started. Since the motor is supplied to the motor, it is possible to prevent the generation of abnormal noise due to the cogging torque of the DC motor and the backlash of the gears when the motor drive is started.
[0080]
According to the DC motor control device of the present invention, the first gear coupled to the rotor shaft of the DC motor is required for rotationally driving the second gear meshed with the first gear. DC current having a value less than a threshold current, which is a value that can rotate and drive the first gear itself, is used as an initial value current, and the DC current is applied only for a predetermined period when the DC motor is started. Since it has an initial value current supply command unit that generates and outputs an initial value current supply command signal for instructing supply to the motor, it is caused by the cogging torque of the DC motor and the backlash of the gears when the motor drive is started. Generation of abnormal noise can be prevented.
[0081]
According to the recording medium of the computer program according to the present invention, a computer program for executing the DC motor control method according to the present invention in a computer system is recorded. The effect of the DC motor control method according to the invention can be obtained.
[Brief description of the drawings]
FIG. 1 is a graph showing in detail a motor current when a motor is driven in a forward direction in a DC motor control method and control apparatus according to the present invention.
FIG. 2 is a block diagram showing a schematic configuration of the ink jet printer.
FIG. 3 is a perspective view showing a configuration around a carriage 3 of an inkjet printer.
4 is an explanatory diagram schematically showing the configuration of a linear encoder 11 attached to a carriage 3. FIG.
FIG. 5 is a timing chart showing waveforms of two output signals of the encoder 11 during normal rotation and reverse rotation of the CR motor.
FIG. 6 is a perspective view showing portions related to paper feeding and paper detection.
FIG. 7 is a block diagram showing a configuration of a DC unit 6 which is a conventional DC motor control device.
FIG. 8 is a graph showing motor current and motor speed of the CR motor 4 controlled by the DC unit 6;
FIG. 9 is an explanatory diagram showing an external configuration of a recording medium on which a program for executing the DC motor control method according to the present invention is recorded and a computer system in which the recording medium is used.
10 is a block diagram showing the configuration of the computer system shown in FIG.
FIG. 11 is a graph showing the relationship between the absolute value of the cogging torque of the DC motor and the phase of the armature (rotor).
FIG. 12 is an explanatory diagram schematically showing the state of gear backlash.
FIG. 13 is a graph showing in detail the motor current when the motor is driven in the forward direction in the conventional DC motor control method and control apparatus.
[Explanation of symbols]
1 Paper feed motor (PF motor)
2 Paper feed driver 3 Carriage 4 Carriage motor (CR motor)
5 Carriage motor driver (CR motor driver)
6 DC unit 6a Position calculator 6b Subtractor 6c Target speed calculator 6d Speed calculator 6e Subtractor 6f Proportional element 6g Integration element 6h Differential element 6j D / A converter 7 Pump motor 8 Pump motor driver 9 Recording head 10 Head driver 11 Linear encoder 12 Code plate 13 Encoder (rotary encoder)
15 Paper detection sensor 16 CPU
17 Timer IC
18 Host computer 19 Interface unit 20 ASIC
21 PROM
22 RAM
23 EEPROM
25 Platen 30 Pulley 31 Timing belt 32 Carriage motor guide member 34 Ink cartridge 35 Capping device 36 Pump unit 37 Cap 50 Recording paper G1, G2 Gear C1, C2 Gear teeth D Gap

Claims (11)

The first gear coupled to the rotor shaft of the DC motor is a direct current having a value less than a threshold current required to rotationally drive the second gear meshed with the first gear. The DC current having a value capable of rotationally driving the first gear itself is supplied to the DC motor as an initial value current for a predetermined period when the DC motor is started. Motor control method.   The predetermined period is a time necessary and sufficient for the teeth of the first gear to abut against the teeth of the second gear in the direction in which the first gear tries to drive the second gear. 2. The DC motor control method according to claim 1, wherein the DC motor control method is set based on a value of the initial value current.   The DC motor control method according to claim 1, wherein the DC motor is a paper feed motor of a printer.   3. The DC motor control method according to claim 1, wherein the DC motor is a carriage motor of a printer.   The DC motor control method according to claim 1, wherein the DC motor is a paper feed motor of a printer.   6. A computer program recording medium having recorded thereon a computer program for executing the DC motor control method according to claim 1 in a computer system. The first gear coupled to the rotor shaft of the DC motor is a direct current having a value less than a threshold current required to rotationally drive the second gear meshed with the first gear. An initial value for instructing the DC motor to be supplied to the DC motor only for a predetermined period when the DC motor is started, with the DC current having a value capable of rotating the first gear itself as an initial value current. A DC motor control device comprising an initial value current supply command unit that generates and outputs a current supply command signal.   The predetermined period is a time sufficient for the teeth of the first gear to abut against the teeth of the second gear in the direction in which the first gear tries to drive the second gear. 8. The DC motor control device according to claim 7, wherein the DC motor control device is set based on a value of the initial value current.   The DC motor control apparatus according to claim 7 or 8, wherein the DC motor is a paper feed motor of a printer.   The DC motor control apparatus according to claim 7, wherein the DC motor is a carriage motor of a printer.   The DC motor control apparatus according to claim 7 or 8, wherein the DC motor is a paper feed motor of a printer.

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