JP2016082859A - Step-out detector and step-out detection method of pulse motor mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a step-out detector and a step-out detection method of a pulse motor capable of detecting step-out of a pulse motor with high accuracy.SOLUTION: If it was a light-shielding state where the amount of light received by a photosensor 80 is less than a threshold, when a motor control section moved a movable body 71 from an origin position by rotating a pulse motor 70 and then resetting to the origin position, the pulse motor 70 is rotated in one direction and the number of pulses is counted until the light-shielding state is changed to a translucent state, and then a determination is made that step-out has occurred if the number of pulses thus counted deviated from a reference acceptable range of the number of pulses.SELECTED DRAWING: Figure 8

Description

  The present invention relates to an apparatus and a method for detecting step-out of a pulse motor in a pulse motor mechanism that moves a movable body by a pulse motor.

  A pulse motor (stepping motor) is a motor having a positioning function that can be directly driven by a pulse signal (digital signal) and can rotate by a certain angle each time a pulse signal is input. In such a pulse motor, the synchronization between the input pulse signal and the motor rotation may be lost particularly during an overload or a sudden speed change, and this state is called step-out.

  As an apparatus for detecting the step-out of the pulse motor, an apparatus using an optical sensor (transmission type optical sensor) is known (for example, Patent Document 1).

  FIG. 9 is a diagram illustrating a basic configuration of a step-out detection apparatus using an optical sensor. That is, a movable body 71 that rotates with the rotation of the pulse motor is attached to the rotation shaft 70 a of the pulse motor 70, and a light shielding body 72 is integrally formed with the movable body 71. And the optical sensor 80 is arrange | positioned in the position of the light-shielding body 72 in the origin position (position of Fig.9 (a)) of the movable body 71. FIG. Specifically, the light emitting portion and the light receiving portion of the optical sensor 80 are arranged so as to sandwich the light shielding body 72 at the origin position of the movable body 71. Therefore, when the movable body 71 is at the origin position, the light sensor 80 is shielded by the light shielding body 72 and enters a light shielding state.

  In such a configuration, if the movable body 71 is moved from the origin position by the rotational drive of the pulse motor 70 and then returned to the origin position again, the optical sensor can be restored if it correctly returns to the origin position in FIG. Since 80 is in a light-shielding state, in this case, it is determined that there is no step-out. On the other hand, as shown in FIG. 9B, when the return position of the movable body 71 is deviated from the origin position, the optical sensor 80 is in a light-transmitting state.

  However, the determination of whether the optical sensor 80 is in the light-transmitting state or the light-shielding state is naturally performed based on a predetermined threshold value. For example, in the case of a slight step-out as shown in FIG. It may be determined that the light is blocked, and as a result, no step-out may be determined. Even such a slight step-out causes a problem particularly when the moving amount of the movable body is small and high moving accuracy (positioning accuracy) is required.

Japanese Patent Laid-Open No. 10-146480

  The problem to be solved by the present invention is to provide a step-out detection device and a step-out detection method for a pulse motor mechanism that can detect step-out of a pulse motor with high accuracy.

According to one aspect of the present invention, a step-out detection device for the following pulse motor mechanism is provided.
“A motor controller that controls the rotation of the pulse motor,
A movable body that moves in accordance with the rotation of the pulse motor;
A light shield integrally formed with the movable body;
An optical sensor having a light emitting portion and a light receiving portion arranged so as to sandwich the light shielding body at the origin position of the movable body;
A light-receiving amount determination unit that determines a light-blocking state when the light-receiving amount of the optical sensor is less than a threshold value, and a light-transmitting state when the light-receiving amount is greater than or equal to the threshold value;
A step-out detection device for a pulse motor mechanism comprising:
When the motor control unit rotates the pulse motor by pulse control to move the movable body from the origin position and then returns to the origin position, when the received light amount determination unit determines the light shielding state, The motor control unit counts the number of pulses until the pulse motor rotates in one direction to change from a light shielding state to a light transmitting state, and the counted number of pulses deviates from a reference pulse number allowable range. A step-out detection device for a pulse motor mechanism that sometimes determines step-out. "

According to another aspect of the present invention, the following step-out detection method for a pulse motor mechanism is provided.
“A motor controller that controls the rotation of the pulse motor,
A movable body that moves in accordance with the rotation of the pulse motor;
A light shield integrally formed with the movable body;
An optical sensor having a light emitting portion and a light receiving portion arranged so as to sandwich the light shielding body at the origin position of the movable body;
A step-out detection method for a pulse motor mechanism comprising:
When the motor control unit rotates the pulse motor by pulse control to move the movable body from the origin position and then return it to the origin position, the received light amount of the photosensor is in a light shielding state that is less than a threshold value. In this case, the pulse motor is rotated in one direction to count the number of pulses until it changes from the light shielding state to the light transmitting state, and the counted number of pulses deviates from the reference pulse number allowable range. A step-out detection method for a pulse motor mechanism, which is determined to be step-out. "

  As described above, according to the present invention, even when the optical sensor is in a light-shielded state when the movable body is returned to the origin, it seems that there is no step-out. A slight step-out can be detected by counting the number of pulses until the rotation is changed to change from the light shielding state to the light transmitting state, and whether or not the counted number of pulses deviates from the reference pulse number allowable range.

  Here, the “reference pulse number allowable range” is set based on the “reference pulse number” until the optical sensor changes from the light shielding state to the light transmitting state when the movable body is moved from the correct origin position. . That is, when the counted number of pulses deviates from the reference pulse number allowable range, this means that the movable body has not returned to the correct origin position. Can also be detected. The “reference pulse number” can be obtained by measuring in advance using the pulse motor after the origin position adjustment, and can be calculated from the dimensional relationship in the design of the pulse motor mechanism and the specifications of the pulse motor. Can also be requested.

  As described above, in the present invention, since the step-out detection is performed after the movable body is returned to the origin position, it is convenient for the step-out detection that the movable body returns to the origin position every time the moving operation is performed. is there.

  In addition, since a slight step-out can be detected in the present invention, there is a remarkable effect in a pulse motor mechanism in which the amount of movement of the movable body is small so that such a slight step-out can be a problem. For example, a pulse motor mechanism in which the range of rotation of the movable body is within a range of 45 ° from the origin position, specifically, a pulse motor mechanism in which the movable body moves the spool of the spool valve as described later. It is effective.

  According to the present invention, a slight step-out that cannot be detected by the prior art can be detected with a simple configuration without taking special measures such as increasing the accuracy of the optical sensor, and the positioning accuracy of the pulse motor mechanism is improved. Can be made.

It is a perspective view which shows the whole structure of the mounting head of the surface mounting machine to which this invention is applied. FIG. 2 is an explanatory diagram showing a mechanism for lowering a spindle (nozzle) in the Z direction in the mounting head of FIG. 1. It is explanatory drawing which shows the structure around a pressing tool in the mechanism which descend | falls the spindle (nozzle) of FIG. 2 to a Z direction. FIG. 2 shows a state in which the spindle (nozzle) is lowered by the pressing tool shown in FIG. 2, (a) shows a state in which the spindle (nozzle) is in an initial position, and (b) shows a state in which the spindle (nozzle) is lowered. Indicates. It is a perspective view which expands and shows the cross section of the nozzle part with which the lower end of the spindle was mounted | worn. It is a figure which shows typically the change of the light reception amount of an optical fiber sensor when a nozzle lands. It is a figure which shows notionally the structural example and operation | movement of a spool valve. It is a conceptual diagram which shows the step-out detection apparatus of the pulse motor mechanism by this invention. It is a figure which shows the basic composition of the step-out detection apparatus using an optical sensor.

  Embodiments of the present invention will be described below with reference to examples in which the present invention is applied to a mounting head of a surface mounter.

  FIG. 1 is a perspective view showing the overall configuration of a mounting head of a surface mounter to which the present invention is applied.

  The mounting head 10 shown in the figure is a rotary head mounting head, and a rotary head 30 is attached to the head body 20 so as to be rotatable in the R direction around the vertical axis. A plurality of spindles 31 are arranged at equal intervals along the circumferential direction of the rotary head 30, and a nozzle 32 that sucks and holds components is attached to the lower end of each spindle 31.

  The rotary head 30 rotates in the R direction by driving an R servo motor 21 installed in the head body 20. Each spindle 31 rotates in the T direction around its axis by driving a T servo motor 22 installed in the head body 20. Further, the head main body 20 is provided with a Z servo motor 23 for raising and lowering the spindle 31a at a specific position in the Z direction along the axial direction. Since a mechanism for rotating the rotary head 30 in the R direction by driving the R servo motor 21 and a mechanism for rotating the respective spindles 31 in the T direction by driving the T servo motor 22 are well known, description thereof will be omitted. A mechanism for lowering the spindle 31a by driving the Z servo motor 23 will be described below.

  FIG. 2 is an explanatory view showing a mechanism for raising and lowering the spindle 31a in the Z direction in the mounting head 10 of FIG. A motor shaft of the Z servo motor 23 arranged in the head body 20 is connected to a screw shaft 24a of a ball screw mechanism 24, and a nut 24b is attached to the screw shaft 24a. And the pressing tool 25 is connected with this nut 24b. Therefore, the drive of the Z servo motor 23 moves the pressing tool 25 in the Z direction together with the nut 24b.

  Only one pressing tool 25 is provided on the head body 20 side. When the spindle 31 is lowered, the spindle 31 to be lowered (spindle 31a at the specific position) is selected by moving the spindle 31 relative to the pressing tool 25, and the spindle is lowered by lowering the pressing tool 25. 31a is lowered. In this embodiment, as shown in FIG. 3, the spindle 31 is moved with respect to the pressing tool 25 by rotating the rotary head 30 in the R direction, and the spindle 31a immediately below the pressing tool 25 is lowered. However, the configuration in which the spindle 31a at the specific position is selected and lowered is not limited to this, and the spindle to be lowered by moving the pressing tool may be selected. Further, there may be two or more specific positions.

  Returning to FIG. 2, the nut 24 b to which the pressing tool 25 is connected is connected to the connecting bar 26 and a spline nut 28 fixed to the head body 20 as a landing detection sensor. An optical fiber sensor 40 is connected. That is, the optical fiber sensor 40 is provided integrally with the pressing tool 25. Therefore, when the pressing tool 25 moves in the Z direction by driving the Z servo motor 23, the optical fiber sensor 40 moves in the Z direction in conjunction with this. This is shown in FIG. 4A shows a state where the spindle 31a is in the initial position, and FIG. 4B shows a state where the spindle 31a is lowered by the pressing tool 25 shown in FIG. The spindle 31 is always urged toward the upper initial position by an elastic body 33 (see FIG. 2) composed of two coil springs.

  The optical fiber sensor 40 has a light emitting part and a light receiving part incorporated on the same axis together with an optical fiber and a lens, and its configuration itself is well known. In this embodiment, as shown in FIG. 2, the optical fiber sensor 40 is disposed obliquely above the nozzle 32 mounted on the lower end of the spindle 31 via a coil spring 34 (elastic body). And the light emission part of the optical fiber sensor 40 emits light P diagonally downward toward the reflective surface 32a of the outer peripheral upper surface of the nozzle 32 shown enlarged in FIG. The light P is received as reflected light by the light receiving portion of the optical fiber sensor 40.

  Here, as described above, the nozzle 32 is attached to the lower end of the spindle 31 via the coil spring 34. Therefore, when the nozzle 32 at the lower end of the spindle 31 is lowered due to the lowering of the spindle 31, the coil spring 34 is compressed, and the vertical position of the nozzle 32 with respect to the spindle 31 is changed. Specifically, the nozzle 32 moves relatively toward the lower end side of the spindle 31.

  On the other hand, the light P emitted from the light emitting portion of the optical fiber sensor 40 is focused on the reflecting surface 32a in the initial state where the nozzle 32 is not landed by the lens 40a shown in FIG. Therefore, when the nozzle 32 is landed and its vertical position is changed, the amount of reflected light reflected by the reflecting surface 32a is reduced, and the amount of light received by the light receiving portion of the optical fiber sensor 40 is reduced (FIG. 6). reference). In this embodiment, the decrease in the amount of received light is detected by the sensor unit 40b of the optical fiber sensor 40. The sensor unit 40b determines that the nozzle 32 has landed when the received light amount has decreased by a predetermined amount, for example, when the amount is less than or equal to the threshold A shown in FIG. 6, and issues a landing detection signal.

  In this specification, “nozzle landing” means that the lower end of the nozzle is landed on the upper surface of the component in the component adsorption (pickup) process, and the component held on the lower end of the nozzle in the component mounting process. Is a concept including both landing on the upper surface of the substrate.

  In the above configuration, the surface mounter having the mounting head 10 sucks and picks up a component from the component supply unit by the nozzle 32 attached to the lower end of the spindle 31 and transfers it to the printed circuit board. Implement in position. In this part pick-up operation and mounting operation, negative pressure and positive pressure are switched and supplied to the nozzle 32, which will be described later.

  Further, at the time of picking up and mounting a component, as described with reference to FIG. 2, the pressing tool 25 presses the upper end surface of the spindle 31a positioned immediately below the holding tool 25, and the spindle 31a is moved in the Z direction. Lower. Thereafter, when the nozzle 32 at the tip of the spindle 31a lands, the coil spring 34 is compressed and the vertical position of the nozzle 32 with respect to the spindle 31a is changed as described above, and the amount of light received by the light receiving portion of the optical fiber sensor 40 is changed. Decrease. And the sensor part 42 of the optical fiber sensor 40 emits a landing detection signal. This landing detection signal is transmitted to the control unit 50 shown in FIG. When receiving the landing detection signal, the control unit 50 stops the Z servo motor 23 that lowers the pressing tool 25. Thereby, the descending stroke of the nozzle 32 is appropriately controlled, and the nozzle 32 is accurately landed.

  Next, operations related to suction and mounting of components by the nozzle 32 will be described.

  As shown in FIG. 5, the nozzle 32 has an air passage 32b therein. That is, the suction of the component is realized by supplying a negative pressure to the air passage 32b through the negative pressure supply path, and the mounting of the component is realized by supplying a positive pressure to the air passage 32b through the positive pressure supply path. The The switching between the negative pressure supply path and the positive pressure supply path is realized by a spool valve.

  FIG. 7 is a diagram conceptually illustrating a configuration example and operation of the spool valve. In addition, in FIG. 7, the shield mentioned later is abbreviate | omitted.

  The spool valve 60 shown in FIG. 7 moves the spool 61 linearly by the rotation of a lever 71 (movable body) coupled to the rotation shaft 70a of the pulse motor 70, thereby providing a negative pressure supply path 62a and a positive pressure supply path. Switching to 62b is performed. The negative pressure supply path 62a is connected to a negative pressure supply source such as a vacuum pump, and the positive pressure supply path 62b is connected to a positive pressure supply source such as a positive pressure air tank.

  The configuration of the spool valve 60 will be described more specifically. The spool 61 has an opening 61a, and the position where the opening 61a perfectly aligns with the negative pressure supply path 62a is the negative pressure switching position A, and the opening 61a. Is a position where the positive pressure supply path 62b completely aligns with the positive pressure switching position C. At the time of component mounting, the negative pressure switching position A is the initial position of the spool 61. There is a preparation position B between the negative pressure switching position A and the positive pressure switching position C. The movement of the spool 61 is controlled by the control unit 50 shown in FIG. 2 performing pulse control of the operation of the pulse motor 70 and rotating the lever 71 as a movable body. That is, the control unit 50 in FIG. 2 is also a “motor control unit” that performs pulse control of the rotation of the pulse motor 70.

  When the component adsorbed to the nozzle is mounted on the substrate, the control unit 50 controls the operation of the pulse motor 70 before the landing of the nozzle, for example, when the nozzle starts the lowering operation. A preliminary operation for moving 61 from the negative pressure switching position A to the preparation position B is executed. When the landing of the nozzle is detected by the optical fiber sensor 40, the control unit 50 controls the operation of the pulse motor 70 and moves the spool 61 from the preparation position B to the positive pressure switching position C by the lever 71. Perform a blow operation. Thereby, a positive pressure is supplied to the nozzle, the vacuum in the nozzle is broken, blow is performed, and the component is mounted on the substrate. When the component mounting is completed, the control unit 50 controls the operation of the pulse motor 70 to return the lever 71 to the neutral position D. This neutral position D is a standby position D for receiving the spool valve 60 of the next spindle 31 by the rotation of the rotary head 30 in the R direction. That is, the spool valve 60 of the next spindle 31 is received at the standby position D. Since the spool 61 of the next spool valve 60 is in the negative pressure switching position A, the spool 61 is sequentially moved to the preparation position B and the positive pressure switching position C as described above, and then the lever 71 is put on standby. Return to position D. Thereafter, this operation is repeated until the mounting of parts by the nozzles of all the spindles 31 is completed.

  Next, the configuration and operation of the step-out detection device for the pulse motor mechanism according to the present invention will be described using the pulse motor 70 of FIG. 7 as an example.

  FIG. 8 is a conceptual diagram showing a step-out detection device for a pulse motor mechanism according to the present invention. The basic configuration of the apparatus is the same as that of FIG. 9, and a movable body 71 (lever) that rotates as the pulse motor 70 rotates is attached to the rotation shaft 70 a of the pulse motor 70. A light blocking body 72 is integrally formed. A transmissive optical sensor 80 is disposed at the position of the light shielding body 72 at the origin position of the movable body 71 (the position of FIG. 9A). Specifically, the light emitting portion and the light receiving portion of the optical sensor 80 are arranged so as to sandwich the light shielding body 72 at the origin position of the movable body 71. Therefore, when the movable body 72 is at the origin position, the light sensor 80 is shielded by the light shielding body 72 and enters a light shielding state.

  Whether the optical sensor 80 is in a light-transmitting state or a light-shielding state is determined based on a predetermined threshold value. That is, when the amount of light received by the sensor 80 is less than the threshold value, it is determined as a light shielding state, and when it is greater than or equal to the threshold value, it is determined as a light transmission state. This determination can be performed by a received light amount determination unit (not shown). The received light amount determination unit can be incorporated in the optical sensor 80, for example.

  In such a configuration, when the movable body 71 is moved from the origin position by the rotational drive of the pulse motor 70 and then returned to the origin position again, the origin position is correctly restored as shown in FIG. 9A. Then, the optical sensor 80 is in a light-shielding state, and in this case, it is determined that there is no step-out. On the other hand, as shown in FIG. 9B, when the return position of the movable body 70 is completely deviated from the origin position, the optical sensor 80 is in a translucent state. In this case, it is determined that there is a step-out. To do.

  On the other hand, as shown in FIG. 8A corresponding to FIG. 9C, in the case of slight step-out, it may be determined that the light is blocked. In this case, in the present invention, the motor control unit 50 described above rotates the pulse motor 70 in one direction to change from the light shielding state (the state shown in FIG. 8A) to the light transmitting state (the state shown in FIG. 8B). Count the number of pulses until it changes. Then, when the counted number of pulses deviates from the “reference pulse number allowable range”, it is determined that the step-out has occurred.

  Here, the “reference pulse number allowable range” is, as described above, when the optical sensor 80 changes from the light shielding state to the light transmitting state when the movable body 71 is moved from the correct origin position (position of FIG. 9A). It is set based on the “reference pulse number” until it changes. That is, when the counted number of pulses deviates from the reference pulse number allowable range, this means that the movable body 71 has not returned to the correct origin position. Key can also be detected.

  For example, if “reference pulse number” is 100 and “reference pulse number allowable range” is set to 100 ± 10, if the above-mentioned counted number of pulses deviates from 100 ± 10, there is a step-out. Judge.

  As described above, since the present invention can detect a slight step-out, the present invention is effective when applied to a pulse motor mechanism in which the range of the rotational operation of the movable body is small and high positioning accuracy is required. For example, in the example of FIG. 7, the range of rotation of the movable body (lever) 71 is as small as about 15 °, and high positioning accuracy is required to accurately switch between the negative pressure supply path 62a and the positive pressure supply path 62b. Is required. Therefore, it is effective to apply the present invention to the configuration as shown in FIG. Furthermore, in the present invention, since the step-out detection is performed after the movable body is returned to the origin position, the movable body (lever) 71 returns to the origin position every time the moving operation is performed as in the example of FIG. This is convenient for step-out detection.

  Although the above embodiment is a case where the movable body 71 rotates by the rotation of the pulse motor 70, the present invention can also be applied to the case where the movable body moves straight by the rotation of the pulse motor.

DESCRIPTION OF SYMBOLS 10 Mounting head 20 Head main body 21 R servo motor 22 T servo motor 23 Z servo motor (elevating means)
24 ball screw mechanism 24a screw shaft 24b nut 25 pressing tool 26 connecting bar 27 spline shaft 28 spline nut 30 rotary head 31, 31a spindle 32 nozzle 32a reflecting surface 33 elastic body 34 coil spring (elastic body)
40 Optical fiber sensor (landing detection sensor)
40a lens 40b sensor unit 50 control unit (motor control unit)
60 Spool valve 61 Spool 61a Open hole 62a Negative pressure supply path 62b Positive pressure supply path 70 Pulse motor 70a Rotating shaft 71 Lever (movable body)
72 light shield 80 transmissive optical sensor

Claims (5)

A motor control unit that controls the rotation of the pulse motor; and
A movable body that moves in accordance with the rotation of the pulse motor;
A light shield integrally formed with the movable body;
An optical sensor having a light emitting portion and a light receiving portion arranged so as to sandwich the light shielding body at the origin position of the movable body;
A light-receiving amount determination unit that determines a light-blocking state when the light-receiving amount of the optical sensor is less than a threshold value, and a light-transmitting state when the light-receiving amount is greater than or equal to the threshold value;
A step-out detection device for a pulse motor mechanism comprising:
When the motor control unit rotates the pulse motor by pulse control to move the movable body from the origin position and then returns to the origin position, when the received light amount determination unit determines the light shielding state, The motor control unit counts the number of pulses until the pulse motor rotates in one direction to change from a light shielding state to a light transmitting state, and the counted number of pulses deviates from a reference pulse number allowable range. A step-out detection device for a pulse motor mechanism that sometimes determines step-out.   The step-out detection device for a pulse motor mechanism according to claim 1, wherein the movable body returns to the original position every time the moving operation is performed.   The step-out detection device for a pulse motor mechanism according to claim 1 or 2, wherein the moving operation of the movable body is a rotation operation, and the range of the rotation operation is within a range of 45 ° from the origin position.   The step-out detection device for a pulse motor mechanism according to any one of claims 1 to 3, wherein the movable body moves a spool of a spool valve. A motor control unit that controls the rotation of the pulse motor; and
A movable body that moves in accordance with the rotation of the pulse motor;
A light shield integrally formed with the movable body;
An optical sensor having a light emitting portion and a light receiving portion arranged so as to sandwich the light shielding body at the origin position of the movable body;
A step-out detection method for a pulse motor mechanism comprising:
When the motor control unit rotates the pulse motor by pulse control to move the movable body from the origin position and then return it to the origin position, the received light amount of the photosensor is in a light shielding state that is less than a threshold value. In this case, the pulse motor is rotated in one direction to count the number of pulses until it changes from the light shielding state to the light transmitting state, and the counted number of pulses deviates from the reference pulse number allowable range. A step-out detection method for a pulse motor mechanism, which is determined to be step-out.