JP6540412B2 - Motor drive mechanism and motor drive method - Google Patents

Description

  The present invention relates to a motor drive mechanism and a motor drive method for controlling the drive of a stepping motor.

  The stepping motor is a pulse motor that rotates at a phase (rotation angle) corresponding to the number of pulses based on the input of a pulse signal, and is widely known as a motor that can accurately control rotation. Due to the accuracy of such rotation control, a stepping motor is used in various devices such as an image forming apparatus (see, for example, Patent Document 1 below).

  For example, a stepping motor may be used also as a dispensing apparatus for aspirating and dispensing a sample in a sample container with a probe. In this case, for example, the arm holding the probe is driven using a stepping motor, so that the probe can be accurately moved into the sample container, and a predetermined amount of sample can be accurately sucked into the probe.

  For such movement control of the arm, a sensor for detecting the rotational position of the stepping motor is usually used. The sensor is composed of, for example, a photo interrupter, and detects the rotational position of the stepping motor based on whether or not the light incident on the sensor is blocked by the rotating body attached to the rotating shaft of the stepping motor. it can. Then, rotation control of the stepping motor is performed on the basis of the rotational position detected by the sensor.

Japanese Patent Laid-Open No. 2002-366002

  FIG. 9A and FIG. 9B are time charts for explaining an aspect when performing rotation control of the stepping motor. The stepping motor rotates at a phase corresponding to the number of pulses, for example, by inputting a clock signal output at a constant cycle as a pulse signal. In this example, by using a stepping motor of a 1-2 phase excitation method, the phase is configured to rotate once by eight pulses. While the stepping motor rotates, the phase is incremented from "0" to "7", and the phase after the second rotation is repeatedly incremented again from "0".

  For example, it is assumed that the phase when the rotation of the stepping motor is stopped based on the detection signal from the sensor at the first use of the device is “5” as shown in FIG. 9A. In this case, when the power supply of the apparatus is turned off after that and the power supply of the apparatus is turned on again, the rotation control of the stepping motor is performed on the basis of the rotational position corresponding to the phase "5". Then, if the detection accuracy of the sensor is high, then the phase when the rotation of the stepping motor is stopped is also "5".

  However, when the detection accuracy of the sensor is low, or when the detection accuracy of the sensor is lowered due to aging, etc., or when vibration occurs in the mechanical part in the apparatus, the repeatability of the stop position of the stepping motor May be impaired. In such a case, for example, as shown in FIG. 9B, the phase may be shifted when the rotation of the stepping motor is stopped based on the detection signal from the sensor.

  In the example of FIG. 9B, the phase when the rotation of the stepping motor is stopped based on the detection signal by the sensor is shifted from “5” to “3” by two phases. In this case, when the power of the apparatus is turned off and the power of the apparatus is turned on again, the rotation control of the stepping motor is performed based on the rotational position corresponding to the phase "3", The stepping motor rotates in a state in which a shift of two phases occurs.

  Such a phase shift of the stepping motor can be fatal in a device requiring accurate operation. For example, in the dispensing apparatus as described above, when the stepping motor rotates while the phase is shifted, the tip position of the probe inserted into the sample container is shifted, which causes an error in the suction amount of the sample. As a result, the sample may not be accurately dispensed.

  In order to prevent such a problem from occurring, for example, a configuration may be considered in which absolute coordinates are measured using a rotary encoder or the like. However, in such a case, although the repeatability of the stop position of the stepping motor can be improved, the mechanism using a rotary encoder or the like is expensive, and there is a problem that the manufacturing cost becomes high.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a motor drive mechanism and a motor drive method capable of improving the reproducibility of the stop position of the stepping motor with an inexpensive configuration.

  A motor drive mechanism according to the present invention includes a stepping motor, a sensor, a storage unit, and a motor control unit. The sensor detects the rotational position of the stepping motor. The storage unit stores a phase when the stepping motor stops at a fixed rotational position as a reference phase. When stopping the rotation of the stepping motor, the motor control unit stops the stepping motor based on a detection signal from the sensor, and then rotates and stops the stepping motor to the reference phase.

  According to such a configuration, after the stepping motor stops based on the detection signal from the sensor, the stepping motor rotates to the reference phase and stops, so the stopping position of the stepping motor is always constant. Also, even if an expensive sensor such as a rotary encoder is not used, storing the reference phase of the stepping motor enables the stepping motor to be accurately stopped based on the reference phase. Therefore, when the detection accuracy of the sensor is low, or when the detection accuracy of the sensor is lowered due to secular change, etc., or even when the mechanical part in the apparatus is vibrating, etc., the stepping motor has an inexpensive configuration. The repeatability of the stop position of can be improved.

  The motor drive mechanism may further include a phase determination processing unit that determines whether the phase when stopping the stepping motor matches the reference phase based on the detection signal from the sensor. . In this case, the motor control unit performs the stepping up to the reference phase only when it is determined that the phase when the stepping motor is stopped is different from the reference phase based on the detection signal from the sensor. The motor may be rotated and stopped.

  According to such a configuration, when the stepping motor stops based on the detection signal from the sensor, the stepping motor rotates to the reference phase and stops only when the phase of the stepping motor is different from the reference position. Therefore, when the phase when the stepping motor stops based on the detection signal from the sensor is the same as the reference phase, no operation for rotating the stepping motor is performed thereafter, so unnecessary operation is minimized. Can be limited.

  The motor drive mechanism may further include a phase difference comparison processing unit that compares a phase difference between the phase when the stepping motor is stopped and the reference phase with a threshold based on a detection signal from the sensor. . In this case, the motor control unit may rotate and stop the stepping motor to the reference phase only when the phase difference is equal to or less than the threshold.

  According to such a configuration, when the phase difference between the phase when the stepping motor stops and the reference phase is larger than the threshold based on the detection signal from the sensor, an operation for rotating the stepping motor thereafter is performed. It does not happen. If the phase difference is larger than the threshold value, there is a possibility that a member such as a sensor or a stepping motor may be broken. Therefore, by restricting the operation of the stepping motor thereafter, the abnormal operation is adversely affected. Can be prevented.

  The motor drive mechanism may further include an abnormality notification processing unit that notifies an abnormality when the phase difference is larger than the threshold.

  According to such a configuration, when the phase difference between the phase when the stepping motor is stopped and the reference phase is larger than the threshold based on the detection signal from the sensor, an abnormality can be notified. As a result, it is possible to notify the worker that there is a high possibility that a member such as a sensor or a stepping motor is broken, so that it is possible to effectively prevent the occurrence of an adverse effect due to an abnormal operation.

  A motor driving method according to the present invention includes a motor stopping step and a reference phase storing step. In the motor stopping step, the stepping motor is stopped based on a detection signal from a sensor that detects the rotational position of the stepping motor. In the reference phase storage step, the phase when the stepping motor is stopped is stored in the storage unit as a reference phase. In the motor stopping step, when stopping the rotation of the stepping motor after the reference phase storing step, the stepping motor is stopped based on a detection signal from the sensor, and then the stepping motor is operated up to the reference phase. Rotate to stop.

  According to the present invention, it is inexpensive even when the detection accuracy of the sensor is low, when the detection accuracy of the sensor is lowered due to secular change, etc., or when vibration occurs in the mechanical part in the apparatus. The configuration can improve the repeatability of the stopping position of the stepping motor.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic plan view which shows the structural example of the dispensing apparatus provided with the motor drive device which concerns on one Embodiment of this invention. It is a schematic sectional drawing for demonstrating the operation | movement at the time of attracting | sucking a sample from a sample container. It is a schematic sectional drawing for demonstrating the operation | movement at the time of attracting | sucking a sample from a sample container. It is a schematic side view which shows the structural example of a probe holding mechanism. It is a top view which shows the structural example of a rotor plate. It is a block diagram which shows an example of the electric constitution of a dispensing apparatus. It is a time chart for explaining the mode at the time of performing rotation control of a rotation motor or a rise-and-fall motor. It is a time chart for explaining the mode at the time of performing rotation control of a rotation motor or a rise-and-fall motor. It is the flowchart which showed an example of the process by the control part at the time of operating a probe arm at the time of first use of a dispensing apparatus. It is the flowchart which showed an example of the process by the control part at the time of operating a probe arm at the time of 2nd and subsequent use of a dispensing apparatus. It is a time chart for explaining the mode at the time of performing rotation control of a stepping motor. It is a time chart for explaining the mode at the time of performing rotation control of a stepping motor.

  FIG. 1 is a schematic plan view showing a configuration example of a dispensing device 1 provided with a motor drive device according to an embodiment of the present invention. The dispensing device 1 is provided, for example, in an analyzer for analyzing various samples such as blood, and can aspirate and dispense a sample from the inside of a plurality of sample containers 2 in which the samples are stored.

  The sample container 2 is set in the sample placement unit 3. The sample placement unit 3 can hold a plurality of sample containers 2. The sample is aspirated from the sample container 2 held by the sample placement unit 3 using the probe 8. The probe 8 is held by the probe holding mechanism 81 so as to extend in the vertical direction (the front and rear direction in the drawing of FIG. 1).

  FIGS. 2A and 2B are schematic cross-sectional views for describing an operation at the time of suctioning a sample from the sample container 2. At the time of sample aspiration operation of aspirating a sample from the sample container 2, the probe 8 is inserted into the sample container 2 from the opening 21 and the pump (not shown) with the probe 8 immersed in the sample in the sample container 2 The sample in the sample container 2 is aspirated by driving the

  The probe holding mechanism 81 is provided with a probe arm 811 extending in the horizontal direction, and the probe 8 is held at one end of the probe arm 811. The probe arm 811 is rotatably held around a rotating shaft 812 attached to the other end. Therefore, when the probe arm 811 is rotated about the rotation axis 812, the probe 8 can be moved horizontally along the arc-shaped track 813 (see FIG. 1). The probe arm 811 can also be moved vertically along the rotation axis 812.

  When inserting the probe 8 into the sample container 2, the probe arm 811 is rotated to horizontally move the probe 8 to the upper side of the sample container 2 (see FIG. 2A), and then the probe arm 811 is vertically lowered. By moving, the probe 8 is inserted into the sample container 2 from the tip (see FIG. 2B). Such movement of the probe 8 is performed by driving a probe drive mechanism (not shown) including a motor and the like.

  When performing the sample dispensing operation, the probe is inserted into the sample container 2 as described above, and the sample aspirating operation is performed by aspirating the sample with the probe 8, and then the probe arm 811 is vertically upward The probe 8 is retracted from the inside of the sample container 2 by moving the Then, by rotating the probe arm 811, the probe 8 is moved horizontally above the dispensing port 814 on the track 813, and the probe arm 811 is moved vertically downward again. As a result, the probe 8 is inserted into the dispensing port 814, and by discharging the sample that has been sucked in advance in this state, it is possible to dispense the sample into the dispensing port 814.

  Reagents may be mixed in the sample dispensed into the dispensing port 814. In the present embodiment, a plurality of reagent containers 4 containing reagents are set in the reagent setting unit 5. The reagent in the reagent container 4 is aspirated by the probe 7. The probe 7 is held by the probe holding mechanism 71 so as to extend in the vertical direction (the front-rear direction in the drawing of FIG. 1).

  The probe 7 for aspirating the reagent and the probe holding mechanism 71 have the same configuration as the probe 8 for aspirating the sample described above and the probe holding mechanism 81, and are provided with a horizontally extending probe arm 711 ing. The probe 7 is held at one end of the probe arm 711 and is rotatably held about a rotation shaft 712 attached to the other end. Therefore, when the probe arm 711 is rotated about the rotation axis 712, the probe 7 can be moved horizontally along the arc-shaped trajectory 713. The probe arm 711 can also be moved vertically along the rotation axis 712.

  The probe 7 for aspirating the reagent and the probe 8 for aspirating the sample move horizontally along different trajectories 713 and 813 respectively, but these trajectories 713 and 813 partially cross in plan view doing. Not only the sample but also the reagent can be dispensed to the dispensing port 814 by arranging the dispensing port 814 at the intersection of the trajectories 713 and 813. The operation of the probe 7 at the time of dispensing the reagent to the dispensing port 814 is the same as the operation of the probe 8 at the time of dispensing the sample to the dispensing port 814 described using FIGS. 2A and 2B. Detailed explanation is omitted.

  FIG. 3 is a schematic side view showing a configuration example of the probe holding mechanism 81. As shown in FIG. The probe holding mechanism 81 is provided with, for example, a rotation motor 820, a rotation plate 821, a rotation sensor 822, an elevation motor 830, an elevation plate 831, an elevation sensor 832 and the like in addition to the probe arm 811 and the rotation shaft 812 described above. .

  The rotation motor 820 is a motor for rotating the probe arm 811 in the horizontal direction, and rotates the rotation shaft 812 to rotate the probe arm 811 attached to the rotation shaft 812. The rotating plate 821 is fixed to the rotating shaft 812. Therefore, when the rotary shaft 812 is rotated by the drive of the rotary motor 820, the rotary plate 821 is also rotated along with the rotary shaft 812.

  FIG. 4 is a plan view showing a configuration example of the rotary plate 821. As shown in FIG. The rotating plate 821 is, for example, a disk-shaped rotating body, and a plurality of notches 823 are formed on the outer peripheral surface thereof. Each notch 823 is located on the same track centering on the insertion hole 826 in which the rotating shaft 812 is inserted. The rotation sensor 822 is configured by, for example, a photo interrupter, and includes a light emitting unit 824 and a light receiving unit 825. The light from the light emitting unit 824 of the rotation sensor 822 is irradiated on the track of each notch 823 of the rotating plate 821.

  Therefore, when any notch 823 of the rotary plate 821 is positioned on the optical axis of the light from the light emitting unit 824, the light is received by the light receiving unit 825 through the notch 823. On the other hand, when any of the notches 823 is not positioned on the optical axis of the light from the light emitting unit 824, the light is blocked by the rotary plate 821, so that the light is not detected by the light receiving unit 825.

  With such a configuration, the rotation sensor 822 can detect the rotational position of the rotational motor 820, more specifically, the rotational position of an object (for example, the rotational shaft 812) rotated by the rotational motor 820. However, the rotation sensor 822 is not limited to a transmission type sensor such as a photo interrupter, but emits light from, for example, a light emitting unit, and detects the rotation position of the object based on whether reflected light from the object is incident. Other sensors may be used, such as a reflection type sensor.

  In the example as shown in FIG. 1, for example, the probe 8 is positioned on the sample container 2 to be dispensed, the position is positioned on the dispensing port 814, etc. Each notch 823 is formed in the plate 821. As a result, when the rotary motor 820 is stopped based on the detection signal from the rotation sensor 822, the probe 8 can be stopped at each horizontal stop position.

  The lift motor 830 is a motor for moving the probe arm 811 up and down in the vertical direction, and is connected to the probe arm 811 via a rotation shaft 833. When the lift motor 830 is driven, the rotary shaft 833 rotates relative to the lift motor 830 so that the rotary shaft 833 moves up and down in the vertical direction. The lift plate 831 is fixed to the rotating shaft 833. Therefore, when the rotary shaft 833 vertically moves in the vertical direction by the drive of the lift motor 830, the lift plate 831 vertically moves together with the rotary shaft 833.

  The vertical position of the lift plate 831 is detected by the lift sensor 832. In the example as shown in FIG. 1, each stop position of the probe 8 in the vertical direction is detected by the elevation sensor 832, for example, the position where the probe 8 is immersed in the sample or the position where it is retracted from the sample. By stopping the lift motor 830, the probe 8 can be stopped at each stop position in the vertical direction. The elevation sensor 832 can be configured by, for example, a transmission sensor or a reflection sensor, but is not limited to these sensors.

  The above-described rotary motor 820 and lifting motor 830 are configured by, for example, stepping motors, and are rotated at a phase corresponding to the number of pulses by inputting a clock signal output in a constant cycle as a pulse signal. In the present embodiment, the rotary motor 820 and the elevation motor 830 are configured by a 1-2 phase excitation type stepping motor in which the phase rotates one turn with eight pulses.

  However, the rotary motor 820 and the elevation motor 830 may be configured by other stepping motors as well as the 1-2 phase excitation type stepping motor. For example, stepping motors of different types such as a two-phase stepping motor or a five-phase stepping motor may be used, or stepping motors of different excitation methods such as a two-phase excitation method or a micro step method may be used. Further, not limited to the clock type, for example, a motor driver using another type of control instruction method such as a phase type may be used.

  FIG. 5 is a block diagram showing an example of the electrical configuration of the dispensing device 1. The dispensing device 1 according to the present embodiment includes, for example, a control unit 9 configured by a CPU (Central Processing Unit) or the like. In addition to the counter 10 for counting the number of pulses when the motors 820 and 830 are rotated, the dispensing device 1 includes, for example, a storage unit 20 configured of a random access memory (RAM) or a hard disk, or a liquid crystal A display unit 30 configured of a display or the like is provided.

  The control unit 9 functions as a motor control unit 91, a phase determination processing unit 92, a phase difference comparison processing unit 93, an abnormality notification processing unit 94, and the like when the CPU executes a program. The motor control unit 91 controls the operation of the motors 820 and 830 based on the detection signals from the sensors 822 and 832. That is, the motor control unit 91 individually rotates the rotational motor 820 and the elevation motor 830 by inputting pulse signals, and individually rotates based on detection signals from the rotation sensor 822 and the elevation sensor 832. Stop.

  The number of pulse signals (number of pulses) input from the motor control unit 91 to the motors 820 and 830 is counted by the counter 10. The counter 10 is provided in association with each of the motors 820 and 830. While each motor 820, 830 rotates, the counter 10 corresponding to each motor 820, 830 is, for example, incremented from "0" to "7", and the phase after the second rotation is repeatedly incremented again from "0". Ru.

  As in the present embodiment, in the motors 820 and 830 consisting of stepping motors of 1-2 phase excitation method in which the phase makes one rotation with 8 pulses, the count value by the counter 10 corresponds to the phase of the motors 820 and 830. ing. Therefore, the phases of the motors 820 and 830 can be determined based on the count value of the counter 10. However, the present invention is not limited to the configuration in which the phases of the motors 820 and 830 are determined using the counter 10. For example, when the control unit 9 has grasped the number of pulses output from the motor control unit 91, the number of pulses The phases of the motors 820 and 830 may be determined based on

  The phases of the motors 820 and 830 are acquired based on the count value of the counter 10 when the motors 820 and 830 stop at fixed acquisition timing, for example, when using the dispensing apparatus 1 for the first time, and the phases are obtained. It is stored in the storage unit 20 as a reference phase. The storage unit 20 is configured by a non-volatile memory, and the reference phase is maintained as stored in the storage unit 20 even when the dispensing device 1 is powered off.

  The reference phase is a phase when the motors 820 and 830 stop at a fixed rotational position based on the detection signals of the sensors 822 and 832, and when stopping the motors 820 and 830 when the dispensing device 1 operates thereafter. Phase that is the reference of Therefore, the acquisition timing is preferably before the detection accuracy of the sensors 822, 832 decreases, that is, during the period when the accuracy of the stop position of the motors 820, 830 based on the detection signals of the sensors 822, 832 is high. .

  The phase determination processing unit 92 determines whether or not the phase when stopping the motors 820 and 830 matches the reference phase based on the detection signals from the sensors 822 and 832. For example, when the dispensing device 1 is used for the second and subsequent times (during dispensing operation), when the motors 820 and 830 are stopped based on the detection signals from the sensors 822, 832, based on the count value of the counter 10. The phases of the motors 820 and 830 are acquired, and it is determined whether or not the phases match the reference phase stored in the storage unit 20.

  At this time, if there is no error factor such as the decrease in detection accuracy of the sensors 822, 832 or the vibration of the mechanical part in the dispensing apparatus 1, the phase of the motor 820, 830 obtained based on the count value of the counter 10 is the reference. Match the phase. However, when there is an error factor as described above, the acquired phase may not match the reference phase. As described above, when the phase determination processing unit 92 determines that the phase when the motors 820 and 830 are stopped based on the detection signals from the sensors 822 and 832 is different from the reference phase, the motor control unit 91 rotates the motors 820 and 830 to the reference phase and stops them.

  That is, when the phase when the rotary motor 820 is stopped based on the detection signal from the rotation sensor 822 is different from the phase stored in the storage unit 20 as the reference phase of the rotary motor 820, the reference phase The rotary motor 820 is rotated and stopped. On the other hand, if the phase when stopping the elevation motor 830 based on the detection signal from the elevation sensor 832 is different from the phase stored in the storage unit 20 as the reference phase of the elevation motor 830, the reference phase The lift motor 830 rotates and stops. These processes may be performed only for either the rotation motor 820 or the elevation motor 830, or may be performed for both.

  As described above, in the present embodiment, when the motors 820 and 830 stop rotating, the motors 820 and 830 stop based on the detection signals from the sensors 822 and 832, and then the motors 820 and 830 rotate to the reference phase. Because the motor 820 is stopped, the stop positions of the motors 820 and 830 are always constant. Also, even if an expensive sensor such as a rotary encoder is not used, storing the reference phases of the motors 820 and 830 allows the motors 820 and 830 to be accurately stopped based on the reference phases. Therefore, when the detection accuracy of the sensors 822, 832 is low, when the detection accuracy of the sensors 822, 832 decreases due to aging, etc., or when the mechanical part in the dispensing apparatus 1 is vibrated, etc. However, the reproducibility of the stop positions of the motors 820 and 830 can be improved with an inexpensive configuration.

  In particular, in the present embodiment, when the motors 820 and 830 stop based on the detection signals from the sensors 822 and 832, the motor 820 to the reference phase is generated only when the phase of the motors 820 and 830 is different from the reference position. 830 rotates and stops. Therefore, if the phase when the motors 820 and 830 stop is the same as the reference phase based on the detection signals from the sensors 822 and 832, the operation for rotating the motors 820 and 830 is not performed thereafter. Therefore, unnecessary operations can be minimized.

  The phase difference comparison processing unit 93 compares the phase difference between the phase when the motors 820 and 830 are stopped and the reference phase with a threshold based on the detection signals from the sensors 822 and 832. Such comparison corresponds to the phase difference between the phase when the rotary motor 820 is stopped and the reference phase corresponding to the rotary motor 820, the phase when the lift motor 830 is stopped, and the lift motor 830. The phase difference with the reference phase to be performed is separately performed. In this case, the threshold values to be compared with each phase difference may be the same value or different values.

  In the present embodiment, when the motor control unit 91 rotates the motors 820 and 830 based on the determination result by the phase determination processing unit 92, different processing is performed according to the comparison result by the phase difference comparison processing unit 93. ing. Specifically, only when the phase differences are equal to or less than the threshold value, the motor control unit 91 rotates the motors 820 and 830 to the reference phase and stops them.

  That is, when the phase difference between the phase when the rotary motor 820 is stopped and the reference phase is larger than the threshold based on the detection signal from the rotation sensor 822 or the elevation motor 830 is based on the detection signal from the elevation sensor 832 If the phase difference between the phase when stopped and the reference phase is larger than the threshold value, then the operation for rotating the rotary motor 820 and the lift motor 830 is not performed. If the phase difference is larger than the threshold value, there is a possibility that a member such as the sensor 822, 832 or the motor 820, 830 may be broken. Operation can prevent adverse effects.

  The abnormality notification processing unit 94 performs processing for notifying an abnormality when the phase difference is larger than the threshold. Specifically, if the phase difference between the phase when the rotary motor 820 is stopped and the reference phase is larger than the threshold based on the detection signal from the rotation sensor 822 or based on the detection signal from the elevation sensor 832 If the phase difference between the phase when the motor 830 stops and the reference phase is larger than the threshold value, the display unit 30 indicates that the operation is abnormal.

  As a result, the operator can be notified that there is a high possibility that a member such as the sensor 822, 832 or the motor 820, 830 is broken, effectively preventing an adverse operation from being caused by abnormal operation. be able to. However, the abnormality notification processing unit 94 is not limited to the configuration in which the abnormality is notified by the display on the display unit 30, but may be configured to notify the abnormality in another aspect such as voice.

  FIGS. 6A and 6B are time charts for describing an aspect when performing rotation control of the rotary motor 820 or the lift motor 830. FIG. For example, it is assumed that the phase when the rotation of the motors 820 and 830 is stopped based on the detection signals from the sensors 822 and 832 when the dispensing device 1 is used for the first time is “5” as shown in FIG. 6A. In this case, “5” is stored in the storage unit 20 as the reference phase.

  If the detection accuracy of the sensors 822, 832 is high, then the phase when the rotation of the motors 820, 830 is stopped is also "5". However, when the detection accuracy of the sensors 822, 832 is low, when the detection accuracy of the sensors 822, 832 is lowered due to aging, etc., or when the mechanical part in the dispensing apparatus 1 is vibrated, etc. The reproducibility of the stop positions of the motors 820 and 830 may be impaired. In such a case, for example, as shown in FIG. 6B, when the rotations of the motors 820 and 830 are stopped based on the detection signals from the sensors 822 and 832, the phases are shifted.

  In the example of FIG. 6B, the phase when the rotation of the stepping motor is stopped based on the detection signals from the sensors 822, 832 is shifted from "5" to "3" by two phases. As described above, when the phase "3" when stopping the motors 820 and 830 based on the detection signals from the sensors 822 and 832 is different from the reference phase "5", the motor up to the reference phase "5" 820, 830 rotate and stop.

  In this example, only when the phase difference between the phase when the motors 820 and 830 are stopped based on the detection signals from the sensors 822 and 832 and the reference phase is equal to or less than the threshold value “2” which is an allowable range, The motors 820 and 830 rotate and stop until the reference phase. In the example of FIG. 6B, since the phase difference is “2” and is equal to or less than the threshold, the motors 820 and 830 rotate to the reference phase and stop. On the other hand, for example, when the phase when stopping the rotation of the stepping motor based on the detection signals from the sensors 822, 832 is "6", "7", etc., the phase difference becomes larger than the threshold. The rotation control as described above is not performed, and an abnormality is notified. However, the threshold is not limited to “2”.

  FIG. 7 is a flowchart showing an example of processing by the control unit 9 when operating the probe arm 811 at the first use of the dispensing apparatus 1. When the probe arm 811 is operated, the motor control unit 91 starts the rotation of the motors 820 and 830 (step S101), and the counting of the number of pulses by the counter 10 is started (step S102). Then, the motors 820 and 830 are stopped based on the detection signals from the sensors 822 and 832.

  That is, when a detection signal is input from the sensors 822, 832 to the control unit 9 (Yes in step S103), the motor control unit 91 stops the rotation of the motors 820, 830 (step S104: motor stop step) The counting of the number of pulses by the counter 10 is stopped (step S105). Then, the phase when the motors 820 and 830 stop is stored in the storage unit 20 as a reference phase (step S106: reference phase storage step).

  FIG. 8 is a flow chart showing an example of processing by the control unit 9 when operating the probe arm 811 when the dispensing device 1 is used for the second and subsequent times. When the probe arm 811 is operated during the second and subsequent use of the dispensing apparatus 1, the motor control unit 91 starts rotation of the motors 820 and 830 as in the first use (step S201). Counting of the number of pulses by 10 is started (step S202). Then, the motors 820 and 830 are stopped based on the detection signals from the sensors 822 and 832.

  That is, also when stopping the motors 820 and 830 after the reference phase storage step (step S106 in FIG. 7), first, when a detection signal is input from the sensors 822 and 832 to the control unit 9 (at step S203) Yes), the motor control unit 91 stops the rotation of the motors 820 and 830 (step S204: motor stopping step), and the counting of the number of pulses by the counter 10 is stopped (step S205).

  Thereafter, based on the detection signals from the sensors 822, 832, the phases when the motors 820, 830 are stopped are confirmed (step S206), and it is determined whether the phases match the reference phase (step S207). : Phase determination step). As a result, when it is determined that the phase matches the reference phase (Yes in step S207), no phase shift occurs, and the process ends. On the other hand, when it is determined that the phase is different from the reference phase (No in step S207), the phase difference between the phase and the reference phase is calculated (step S208), and the calculated phase difference is compared with the threshold. (Step S209: phase difference comparison step).

  If the phase difference is equal to or less than the threshold (Yes in step S209), the motor control unit 91 rotates the motors 820 and 830 by the phase difference up to the reference phase and stops the motor (step S210: motor stopping step). On the other hand, when the phase difference is larger than the threshold (No in step S209), the operator is notified of the abnormality by display on the display unit 30 (step S211: abnormality notification step).

  In the above embodiments, the configuration has been described in which the rotary motor 820 and the lift motor 830 are both configured by stepping motors, and the rotational positions of the motors 820 and 830 are detected by the sensors 822 and 832. However, not limited to such a configuration, only one of the rotary motor 820 and the lift motor 830 is configured by a stepping motor, and the rotational positions of the motors 820 and 830 are detected by the sensors 822 and 832. It may be.

  Further, the probe holding mechanism 81 is not limited to the configuration as shown in FIG. 3, and may be configured to move the probe 8 in the horizontal direction or the vertical direction using another mechanism such as an XYZ stage. In this case, as long as the probe 8 is moved using the stepping motor, the above-described rotation control may be performed when the rotation of the stepping motor is stopped.

  Furthermore, not only the probe holding mechanism 81 for moving the probe 8 for suctioning the sample, for example, the probe holding mechanism 71 for moving the probe 7 for suctioning the reagent is provided with a stepping motor, and rotation of the stepping motor At the time of stopping, the above-described rotation control may be performed. In this case, the probe holding mechanism 71 may be the same mechanism as the probe holding mechanism 81 as shown in FIG. 3, or the piercer 7 may be horizontally or vertically using another mechanism such as, for example, an XYZ stage. It may be configured to move in the direction.

  However, the rotation control described above is performed when stopping the rotation of the stepping motor used for the operation of the other parts such as the piercer provided in the dispensing apparatus 1 as well as the probes 7 and 8. It may be. Furthermore, the present invention can be applied not only to the dispensing apparatus 1 but also to various analyzers such as, for example, a spectrophotometer, as well as to various apparatuses such as office machines such as copiers and optical machines such as cameras. be able to.

DESCRIPTION OF SYMBOLS 1 dispensing apparatus 2 sample container 3 sample setting part 4 reagent container 5 reagent installation part 7 probe 8 probe 9 control part 10 counter 20 memory part 21 opening part 30 display part 71 probe holding mechanism 81 probe holding mechanism 91 motor control part 92 phase Judgment processing unit 93 Phase difference comparison processing unit 94 Abnormality notification processing unit 711 Probe arm 712 Rotor axis 713 Trajectory 811 Probe arm 812 Rotor axis 813 Orbit 814 Dispensing port 820 Rotor motor 821 Rotor plate 822 Rotation sensor 823 Notch 824 Light emitter 825 Light receiving unit 826 Insertion hole 830 Lifting motor 831 Lifting plate 832 Lifting sensor 833 Rotation axis

Claims (5)

A stepping motor, a sensor for detecting a rotational position of the stepping motor, a storage unit for storing a phase when the stepping motor stops at a constant rotational position as a reference phase, and stopping the rotation of the stepping motor And stopping the stepping motor with a predetermined rotational position as a target position based on a detection signal from the sensor , and then rotating and stopping the stepping motor to the reference phase corresponding to the predetermined rotational position. And a control unit. The motor control unit further includes a phase determination processing unit that determines whether a phase when the stepping motor is stopped matches the reference phase based on a detection signal from the sensor. The stepping motor is rotated to the reference phase and stopped only when it is determined that the phase when the stepping motor is stopped is different from the reference phase based on the detection signal of The motor drive mechanism according to claim 1. The motor control unit further includes a phase difference comparison processing unit that compares a phase difference between the phase when the stepping motor is stopped and the reference phase with a threshold based on a detection signal from the sensor. 3. The motor drive mechanism according to claim 1, wherein the stepping motor is rotated to the reference phase and stopped only when the value is equal to or less than the threshold value. The motor drive mechanism according to claim 3, further comprising an abnormality notification processing unit that notifies an abnormality when the phase difference is larger than the threshold. A motor stopping step of stopping the stepping motor based on a detection signal from a sensor which detects a rotational position of the stepping motor; and a reference phase storing step of storing a phase when the stepping motor stops as a reference phase in a storage unit In the motor stopping step, when stopping the rotation of the stepping motor after the reference phase storing step, the stepping motor is set to have a predetermined rotational position as a target position based on a detection signal from the sensor. A motor driving method comprising: stopping and stopping the stepping motor to the reference phase corresponding to the predetermined rotational position after stopping.

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