JP2017058160A - Motor drive mechanism and motor drive method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor drive mechanism and a motor drive method with which it is possible to improve the reproducibility of the stop position of a stepping motor in an inexpensive configuration.SOLUTION: When the rotation of a stepping motor is to be stopped, the stepping motor is stopped on the basis of a detection signal from a sensor (step S204) and then the stepping motor is rotated till a reference phase and stopped (step S210). Thus, the stop position of the stepping motor is always constant. Furthermore, by keeping the reference phase of the stepping motor stored in memory, it is possible to accurately stop the stepping motor on the basis of the reference phase, without using an expensive sensor such as a rotary encoder.SELECTED DRAWING: Figure 8

Description

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

  A 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, stepping motors are used in various devices such as image forming apparatuses (see, for example, Patent Document 1 below).

  For example, a stepping motor may be used also for a dispensing device for sucking and dispensing a sample in a sample container with a probe. In this case, for example, the arm that holds the probe is driven using a stepping motor, so that the probe can be accurately moved into the sample container, and a certain amount of sample can be sucked into the probe with high accuracy.

  For such arm movement control, 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 can detect the rotational position of the stepping motor based on whether or not light incident on the sensor is blocked by a rotating body attached to the rotating shaft of the stepping motor. it can. Then, rotation control of the stepping motor is performed with reference to the rotation position detected by the sensor.

JP 2002-366002 A

  FIG. 9A and FIG. 9B are time charts for explaining aspects when performing rotation control of the stepping motor. The stepping motor rotates at a phase corresponding to the number of pulses, for example, when a clock signal output at a constant period is input as a pulse signal. In this example, a 1-2 phase excitation stepping motor is used, so that the phase is rotated once by 8 pulses. While the stepping motor rotates, the phase is incremented from “0” to “7”, and the phases after the second rotation are repeatedly incremented from “0” again.

  For example, when the apparatus is used for the first time, it is assumed that the phase when the rotation of the stepping motor is stopped based on the detection signal from the sensor is “5” as shown in FIG. 9A. In this case, when the apparatus power is turned off and the apparatus power is turned on again, the rotation control of the stepping motor is performed with reference to the rotation position corresponding to the phase “5”. If the detection accuracy of the sensor is high, the phase when the rotation of the stepping motor is subsequently stopped is also “5”.

  However, the reproducibility of the stop position of the stepping motor is low when the sensor detection accuracy is low, when the sensor detection accuracy decreases due to secular change, or when the mechanism in the device is vibrating. May be damaged. In such a case, for example, as shown in FIG. 9B, the phase when the rotation of the stepping motor is stopped may be shifted 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 from the sensor is shifted from “5” to “3” by two phases. In this case, when the power of the apparatus is turned off after that, and when 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 with the two-phase deviation generated.

  Such a phase shift of the stepping motor may be fatal in an apparatus that requires an accurate operation. For example, in a dispensing apparatus as described above, if the stepping motor rotates while the phase is out of phase, the tip position of the probe inserted into the sample container is shifted, resulting in an error in the amount of sample suction. This may cause the sample to be dispensed with high accuracy.

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

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

  The 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 a rotational position of the stepping motor. The storage unit stores, as a reference phase, a phase when the stepping motor stops at a fixed rotational position. 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 the stepping motor to the reference phase to stop it.

  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 stop position of the stepping motor is always constant. Further, by storing the reference phase of the stepping motor without using an expensive sensor such as a rotary encoder, the stepping motor can be accurately stopped based on the reference phase. Therefore, even if the detection accuracy of the sensor is low, the detection accuracy of the sensor is lowered due to aging, etc., or when the vibration is generated in the mechanism part in the device, the stepping motor has an inexpensive configuration. The reproducibility of the stop position can be improved.

  The motor driving mechanism may further include a phase determination processing unit that determines whether or not a phase when the stepping motor is stopped matches the reference phase based on a detection signal from the sensor. . In this case, the motor control unit determines that the stepping motor reaches the reference phase only when it is determined that the phase when stopping the stepping motor 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, if the phase when the stepping motor is stopped based on the detection signal from the sensor is the same as the reference phase, the operation for rotating the stepping motor is not performed after that, so the useless operation is minimized. To the limit.

  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 value.

  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, the operation for rotating the stepping motor is performed thereafter. Not done. If the above phase difference is larger than the threshold value, there is a possibility that a member such as a sensor or a stepping motor is broken. Therefore, by restricting the operation of the subsequent stepping motor, an adverse effect is caused by abnormal operation. 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 value.

  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 abnormality can be notified. Thereby, since it is possible to notify the operator that there is a high possibility that a member such as a sensor or a stepping motor has failed, it is possible to effectively prevent an adverse effect from being caused by an abnormal operation.

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

  According to the present invention, even if the detection accuracy of the sensor is low, the detection accuracy of the sensor is lowered due to secular change, or the case where vibration is generated in the mechanism portion in the apparatus, it is inexpensive. With the configuration, the reproducibility of the stop position of the stepping motor can be improved.

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 rotating plate. It is a block diagram which shows an example of the electrical constitution of a dispensing apparatus. It is a time chart for demonstrating the aspect at the time of performing rotation control of a rotation motor or a raising / lowering motor. It is a time chart for demonstrating the aspect at the time of performing rotation control of a rotation motor or a raising / lowering 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 time 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 the second time use of a dispensing apparatus. It is a time chart for demonstrating the aspect at the time of performing rotation control of a stepping motor. It is a time chart for demonstrating the aspect 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 apparatus 1 is provided in an analyzer for analyzing various samples such as blood, and can sample and dispense samples from a plurality of sample containers 2 in which the samples are stored.

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

  2A and 2B are schematic cross-sectional views for explaining an operation when a sample is aspirated from the sample container 2. FIG. During the sample suction operation for sucking the sample from the sample container 2, the probe 8 is inserted into the sample container 2 from the opening 21 and the probe 8 is immersed in the sample in the sample container 2 (not shown). Is driven, the sample in the sample container 2 is aspirated.

  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 held rotatably about a rotation shaft 812 attached to the other end. Therefore, if the probe arm 811 is rotated around the rotation axis 812, the probe 8 can be moved in the horizontal direction along the arcuate track 813 (see FIG. 1). The probe arm 811 can also be moved in the vertical direction along the rotation axis 812.

  When inserting the probe 8 into the sample container 2, the probe arm 811 is rotated to move the probe 8 horizontally above the sample container 2 (see FIG. 2A), and then the probe arm 811 is moved vertically downward. 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 driving mechanism (not shown) including a motor or the like.

  When performing the sample dispensing operation, the probe is inserted into the sample container 2 as described above, and the sample is aspirated by aspirating the sample with the probe 8, and then the probe arm 811 is moved vertically upward. To move the probe 8 from the sample container 2. 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. Thereby, the probe 8 is inserted into the dispensing port 814, and the sample can be dispensed into the dispensing port 814 by discharging the sample sucked in advance in this state.

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

  The probe 7 and the probe holding mechanism 71 for sucking the reagent have the same configuration as the probe 8 and the probe holding mechanism 81 for sucking the sample, and are provided with a probe arm 711 extending in the horizontal direction. ing. The probe arm 711 holds the probe 7 at one end thereof, and is held rotatably about a rotation shaft 712 attached to the other end. Accordingly, if the probe arm 711 is rotated about the rotation shaft 712, the probe 7 can be moved in the horizontal direction along the arcuate track 713. Further, the probe arm 711 can be moved in the vertical direction along the rotation shaft 712.

  The probe 7 for aspirating the reagent and the probe 8 for aspirating the sample move in the horizontal direction along different trajectories 713 and 813, respectively, but these trajectories 713 and 813 partially intersect in plan view. doing. By disposing the dispensing port 814 at the intersection of the tracks 713 and 813, not only the sample but also the reagent can be dispensed to the dispensing port 814. The operation of the probe 7 when dispensing the reagent to the dispensing port 814 is the same as the operation of the probe 8 when dispensing the sample to the dispensing port 814 described with reference to FIGS. 2A and 2B. Detailed description is omitted.

  FIG. 3 is a schematic side view showing a configuration example of the probe holding mechanism 81. In addition to the probe arm 811 and the rotation shaft 812, the probe holding mechanism 81 includes, for example, a rotation motor 820, a rotation plate 821, a rotation sensor 822, a lift motor 830, a lift plate 831, a lift sensor 832, and the like. .

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

  FIG. 4 is a plan view showing a configuration example of the rotating plate 821. 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 an insertion hole 826 through which the rotation shaft 812 is inserted. The rotation sensor 822 is configured by a photo interrupter, for example, and includes a light emitting unit 824 and a light receiving unit 825. Light from the light emitting unit 824 of the rotation sensor 822 is irradiated onto the trajectory of each notch 823 of the rotating plate 821.

  Therefore, when any notch 823 of the rotating 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 none of the notches 823 is located on the optical axis of the light from the light emitting unit 824, the light is blocked by the rotating plate 821, and thus the light is not detected by the light receiving unit 825.

  With such a configuration, the rotation sensor 822 can detect the rotation position of the rotation motor 820, more specifically, the rotation position of an object (for example, the rotation shaft 812) rotated by the rotation motor 820. However, the rotation sensor 822 is not limited to a transmissive sensor such as a photo interrupter. For example, the rotation sensor 822 irradiates light from a light emitting unit and detects the rotation position of the object based on whether or not reflected light from the object is incident. It may be configured by other sensors such as a reflective sensor.

  In the example as shown in FIG. 1, for example, the probe 8 is rotated in association with each stop position of the probe 8 such as a state where the probe 8 is located on the sample container 2 to be dispensed or a state where the probe 8 is located on the dispensing port 814. Each notch 823 is formed in the plate 821. Thereby, if the rotation motor 820 is stopped based on the detection signal from the rotation sensor 822, the probe 8 can be stopped at each stop position in the horizontal direction.

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

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

  The rotation motor 820 and the lifting motor 830 described above are constituted by, for example, stepping motors, and rotate at a phase corresponding to the number of pulses when a clock signal output at a constant period is input as a pulse signal. In this embodiment, the rotary motor 820 and the lifting motor 830 are configured by a 1-2 phase excitation stepping motor whose phase is rotated once by 8 pulses.

  However, the rotary motor 820 and the elevating motor 830 are not limited to the 1-2 phase excitation stepping motor, and may be constituted by other stepping motors. For example, a different type of stepping motor such as a two-phase stepping motor or a five-phase stepping motor may be used, or a different stepping motor such as a two-phase excitation method or a microstep method may be used. Further, not only the clock type but also a motor driver using another type of control command 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 apparatus 1. The dispensing apparatus 1 according to the present embodiment includes a control unit 9 configured by, for example, a CPU (Central Processing Unit). In addition, the dispensing device 1 includes a counter 10 for counting the number of pulses when the motors 820 and 830 are rotated, a storage unit 20 including, for example, a RAM (Random Access Memory) or a hard disk, and a liquid crystal. A display unit 30 including a display device 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 rotation motor 820 and the lifting motor 830 by inputting pulse signals, respectively, and rotates individually based on the detection signals from the rotation sensor 822 and the lifting 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 incremented from “0” to “7”, for example, and the phase after the second rotation is incremented again from “0” again. The

  As in this embodiment, in motors 820 and 830 composed of stepping motors of the 1-2 phase excitation method in which the phase is rotated once by 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 configuration is not limited to the configuration in which the phase of the motors 820 and 830 is determined using the counter 10. For example, when the control unit 9 knows 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 above.

  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 are stopped at a constant acquisition timing, for example, when the dispensing device 1 is used for the first time. The reference phase is stored in the storage unit 20. The storage unit 20 is configured by a nonvolatile memory, and the reference phase is maintained in the state stored in the storage unit 20 even when the dispensing apparatus 1 is turned off.

  The reference phase is a phase when the motors 820 and 830 are stopped at a fixed rotational position based on the detection signals of the sensors 822 and 832. When the dispensing device 1 is subsequently operated, the motors 820 and 830 are stopped. This is the phase that serves as a reference. Therefore, the acquisition timing is preferably before the detection accuracy of the sensors 822 and 832 is lowered, that is, during a period in which the accuracy of the stop positions of the motors 820 and 830 based on the detection signals of the sensors 822 and 832 is high. .

  The phase determination processing unit 92 determines whether or not the phase when the motors 820 and 830 are stopped 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 time or later (during dispensing operation), when the motors 820 and 830 are stopped based on the detection signals from the sensors 822 and 832, based on the count value of the counter 10. Thus, 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, the phase of the motors 820 and 830 acquired based on the count value of the counter 10 is the reference if there is no error factor such as a decrease in detection accuracy of the sensors 822 and 832 and vibration of the mechanism unit in the dispensing device 1. 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 In step 91, the motors 820 and 830 are rotated to the reference phase and stopped.

  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 Until the rotary motor 820 rotates and stops. On the other hand, if the phase when stopping the lifting motor 830 based on the detection signal from the lifting sensor 832 is different from the phase stored in the storage unit 20 as the reference phase of the lifting motor 830, the reference phase The elevating motor 830 rotates and stops. These processes may be performed only for one of the rotary motor 820 and the lifting motor 830, or may be performed for both.

  As described above, in the present embodiment, when the rotation of the motors 820 and 830 stops, the motors 820 and 830 rotate to the reference phase after the motors 820 and 830 stop based on the detection signals from the sensors 822 and 832. Therefore, the stop positions of the motors 820 and 830 are always constant. Further, by storing the reference phase of the motors 820 and 830 without using an expensive sensor such as a rotary encoder, the motors 820 and 830 can be accurately stopped based on the reference phase. Therefore, the detection accuracy of the sensors 822 and 832 is low, the detection accuracy of the sensors 822 and 832 is lowered due to secular change, or the case where vibration is generated in the mechanism unit in the dispensing apparatus 1. 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 are stopped based on the detection signals from the sensors 822 and 832, the motors 820 and 830 reach the reference phase only when the phases of the motors 820 and 830 are different from the reference position. 830 rotates and stops. Therefore, if the phase when the motors 820 and 830 are stopped based on the detection signals from the sensors 822 and 832 is the same as the reference phase, the operation for rotating the motors 820 and 830 is not performed thereafter. Therefore, useless operations can be minimized.

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

  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 each phase difference is 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 rotation motor 820 stops based on the detection signal from the rotation sensor 822 and the reference phase is larger than the threshold value, or when the lifting motor 830 moves based on the detection signal from the lifting sensor 832. When the phase difference between the phase when stopped and the reference phase is larger than the threshold value, the operation for rotating the rotary motor 820 and the lifting motor 830 is not performed thereafter. If the phase difference is larger than the threshold value, there is a possibility that the members such as the sensors 822 and 832 or the motors 820 and 830 are malfunctioning. It is possible to prevent an adverse effect from being caused by an operation.

  The abnormality notification processing unit 94 performs processing for notifying abnormality when the phase difference is larger than the threshold value. Specifically, when the phase difference between the phase when the rotation motor 820 is stopped based on the detection signal from the rotation sensor 822 and the reference phase is larger than the threshold value, or when the movement is lifted based on the detection signal from the lift sensor 832 When the phase difference between the phase when the motor 830 is stopped and the reference phase is larger than the threshold value, the display unit 30 displays an abnormality.

  Thereby, since it is possible to notify the operator that there is a high possibility that a member such as the sensors 822 and 832 or the motors 820 and 830 is out of order, it is possible to effectively prevent an adverse effect caused by an abnormal operation. be able to. However, the abnormality notification processing unit 94 is not limited to a configuration that notifies the abnormality by display on the display unit 30, and may be configured to notify the abnormality in other modes such as voice.

  6A and 6B are time charts for explaining an aspect when performing rotation control of the rotary motor 820 or the lifting motor 830. For example, when the dispensing apparatus 1 is used for the first time, 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 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 and 832 is high, the phase when the rotation of the motors 820 and 830 is subsequently stopped is also “5”. However, when the detection accuracy of the sensors 822 and 832 is low, when the detection accuracy of the sensors 822 and 832 is reduced due to secular change, or when the mechanism part in the dispensing device 1 is vibrated. 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, the phase when the rotations of the motors 820 and 830 are stopped is shifted based on the detection signals from the sensors 822 and 832.

  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 and 832 is shifted from “5” to “3” by two phases. As described above, when the phase “3” 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 “5”, the motor reaches the reference phase “5”. 820 and 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 smaller than a threshold value “2” that is an allowable range, The motors 820 and 830 are rotated to the reference phase and stopped. In the example of FIG. 6B, since the phase difference is “2” and below the threshold value, the motors 820 and 830 rotate to the reference phase and stop. On the other hand, for example, when the phase when the rotation of the stepping motor is stopped based on detection signals from the sensors 822 and 832 is “6” or “7”, the phase difference is larger than the threshold value. The rotation control as described above is not performed, and an abnormality is notified. However, the threshold value 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 when the dispensing apparatus 1 is used for the first time. 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 counter 10 starts counting the number of pulses (step S102). Then, the motors 820 and 830 are stopped based on detection signals from the sensors 822 and 832.

  That is, when a detection signal is input from the sensors 822 and 832 to the control unit 9 (Yes in step S103), the motor control unit 91 stops the rotation of the motors 820 and 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 are stopped is stored in the storage unit 20 as a reference phase (step S106: reference phase storage step).

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

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

  Thereafter, the phase when the motors 820 and 830 are stopped is confirmed based on the detection signals from the sensors 822 and 832 (step S206), and it is determined whether or not the phase matches the reference phase (step S207). : Phase determination step). As a result, if it is determined that the phase matches the reference phase (Yes in step S207), the process is terminated as it is because no phase shift has occurred. 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 value. (Step S209: phase difference comparison step).

  If the phase difference is equal to or smaller than the threshold value (Yes in step S209), the motor control unit 91 rotates the motors 820 and 830 by the phase difference to the reference phase and stops them (step S210: motor stop step). On the other hand, when the phase difference is larger than the threshold value (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 embodiment, the configuration in which both the rotary motor 820 and the lifting motor 830 are configured by stepping motors and the rotational positions of the motors 820 and 830 are detected by the sensors 822 and 832 has been described. However, the present invention is not limited to such a configuration, and only one of the rotary motor 820 and the lifting 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. There may be.

  Further, the probe holding mechanism 81 is not limited to the configuration 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 a stepping motor, the rotation control described above may be performed when the rotation of the stepping motor is stopped.

  Furthermore, not only the probe holding mechanism 81 that moves the probe 8 for sucking the sample, but also, for example, a probe holding mechanism 71 for moving the probe 7 for sucking the reagent is provided with a stepping motor, and the stepping motor rotates. When 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 is moved in the horizontal direction or the vertical direction using another mechanism such as an XYZ stage. It may be configured to move in the direction.

  However, not only the probes 7 and 8 but also the above-described rotation control is performed when stopping the rotation of the stepping motor used for the operation of other parts such as the piercer provided in the dispensing device 1. There may be. Furthermore, the present invention is not limited to the dispensing apparatus 1 and can be applied to various analysis apparatuses such as a spectrophotometer, and also to various apparatuses such as office equipment such as a copy machine and optical equipment such as a camera. 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 | storage part 21 Opening part 30 Display part 71 Probe holding mechanism 81 Probe holding mechanism 91 Motor control part 92 Phase Determination processing unit 93 Phase difference comparison processing unit 94 Abnormality notification processing unit 711 Probe arm 712 Rotating shaft 713 Orbit 811 Probe arm 812 Rotating shaft 813 Orbit 814 Dispensing port 820 Rotating motor 821 Rotating plate 822 Rotating sensor 823 Notch 824 Light emitting unit 825 Light-receiving part 826 Insertion hole 830 Lifting motor 831 Lifting plate 832 Lifting sensor 833 Rotating shaft

Claims (5)

A stepping motor,
A sensor for detecting the rotational position of the stepping motor;
A storage unit for storing a phase when the stepping motor is stopped at a fixed rotational position as a reference phase;
A motor control unit that, when stopping the rotation of the stepping motor, stops the stepping motor based on a detection signal from the sensor and then stops the stepping motor by rotating it to the reference phase; The motor drive mechanism characterized by this. A phase determination processing unit that determines whether a phase when the stepping motor is stopped based on a detection signal from the sensor matches the reference phase;
The motor control unit rotates the stepping motor to the reference phase only when it is determined that the phase when the stepping motor is stopped based on a detection signal from the sensor is different from the reference phase. The motor drive mechanism according to claim 1, wherein the motor drive mechanism is stopped. A phase difference comparison processing unit that compares a phase difference between the phase when the stepping motor is stopped based on a detection signal from the sensor and the reference phase with a threshold value;
3. The motor drive mechanism according to claim 1, wherein the motor control unit rotates and stops the stepping motor to the reference phase only when the phase difference 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 value. A motor stop step for stopping the stepping motor based on a detection signal from a sensor for detecting a rotational position of the stepping motor;
A reference phase storage step of storing the phase when the stepping motor is stopped as a reference phase in a storage unit,
In the motor stop step, when stopping the rotation of the stepping motor after the reference phase storage step, the stepping motor is stopped based on a detection signal from the sensor and then up to the reference phase. The motor drive method characterized by rotating and stopping.

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