JP4931772B2 - Electronic component mounting equipment - Google Patents

Description

  The present invention relates to an electronic component mounting apparatus, and in particular, improves the rotational position accuracy around the axis of a nozzle that holds an electronic component (hereinafter also simply referred to as a component), improves mounting accuracy, and establishes stable mounting. It is related with the electronic component mounting apparatus which can do.

  In the electronic component mounting apparatus, as exemplified in Patent Document 1, a detachable suction nozzle is mounted on a movable mounting head, moved to a component supply position of a component supply unit, the mounting head is lowered to the component, The suction hole is evacuated to suck the component, pick up the component, move onto the conveyed circuit board, and mount the suction component at a predetermined position on the circuit board.

  In such an electronic component mounting device, if there is a position shift or tilt shift in the suction of the component by the suction nozzle, the component will not be mounted at the correct substrate position, so it is fixedly placed on the laser aligner attached to the mounting head or on the device side Based on the component image obtained by the component recognition camera, the suction posture of the suction component (part center and tilt of the component) is calculated, the deviation between the center of the component and the suction center and the suction tilt are corrected, and the component is mounted on the circuit board. ing.

  Here, as illustrated in the bottom view of FIG. 1, in the laser aligner 33, for example, a laser R emitted from a laser emitting unit 33 a including a laser diode is irradiated from the side surface of the component P, and the laser R hits the component P. In a place where there is a shadow and there is no part, the laser light receiving part 33b including the laser light receiving element recognizes the pickup position of the part P by using the laser light receiving part 33b as it is.

  This laser aligner is mounted on a mounting head that picks up components from the supply unit. This laser aligner recognizes the pickup position of the component, corrects the misalignment, rotates it in the specified mounting direction, and mounts the component. I was doing.

JP-A-2005-183412 (FIGS. 1 to 3)

  However, in the conventional electronic component mounting apparatus, due to structural limitations, as shown in FIG. 2, the θ-axis rotation mechanism 19 of the mounting head is respectively connected to the pulley 19c on the θ-axis motor 19a and the actual drive shaft 17b of the suction nozzle 17a. 19d and semi-closed loop control for controlling the rotational position by the output of an encoder (referred to as a motor encoder) 19b built in the θ-axis motor 19a when the power is transmitted using the belt 19e. Here, as the motor encoder 19b, an absolute encoder that can detect an absolute position but is not an expensive ABS encoder is generally used, and an inexpensive incremental encoder that can detect only a displacement amount is used.

  At this time, due to the difference in reduction ratio between the pulley and the belt, if the pulley does not rotate several times, the belt rotates once and does not mesh with the same tooth at the same position. Accordingly, the rotational position of the actual drive shaft 17d is usually caused by the meshing with the teeth of the metal pulley, the backlash of the belt, or the like due to the difference in the shape of the plastic belt depending on the tooth location. There is a difference between the output of the motor encoder 19b and there is a possibility of affecting the mounting accuracy. To improve the mounting accuracy, it is indispensable to solve this problem.

  In order to solve such problems, it may be possible to provide an encoder on the actual drive shaft and perform full closed loop control, but it is not only necessary to provide a separate encoder on the nozzle side, but also in terms of cost. Also had the problem of becoming expensive.

  The present invention has been made to solve the above-described conventional problems, and has an object to enable highly accurate control of the rotational position of the θ-axis without providing an encoder for full-closed loop control on the nozzle side. To do.

  The present invention includes a nozzle that is rotatable about an axis, a θ-axis motor that rotates the nozzle, and a belt that transmits a driving force of the θ-axis motor to the nozzle. In an electronic component mounting apparatus for mounting an electronic component held by a nozzle in a component supply unit on a substrate, a belt mark attached to the belt, a belt mark detection sensor for detecting the belt mark, and the belt The problem is solved by providing a nozzle and means for correcting the rotational position deviation of the θ-axis motor with reference to the output of the mark detection sensor.

  Here, the belt may be a toothed belt, and the number of teeth of the pulleys attached to the nozzle and the θ-axis motor may be the same.

  According to the present invention, it is possible to correct all the operations of the semi-closed loop control of the θ axis, the actual operation accuracy of the θ axis is improved, and a full closed loop control encoder is not provided on the nozzle side. Control equivalent to closed loop control is possible. Therefore, actual operation accuracy can be improved by mounting minute parts or parts (BGA or flip chip) that require precision in the production of electronic circuit boards.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 3 is a schematic diagram of the electronic component mounting apparatus. As shown in FIG. 3, the electronic component mounting apparatus 1 includes a board conveyance path 15 extending in the left-right direction slightly rearward from the central portion, and the front of the apparatus 1. A component supply device (feeder) 11 that supplies components mounted on the circuit board 10, an X-axis moving mechanism 12 and a Y-axis disposed on the front of the device 1. A moving mechanism 13 is provided. The X-axis moving mechanism 12 moves the mounting head 17 including a plurality of suction nozzles 17a for sucking parts in the X-axis direction, and the Y-axis moving mechanism 13 moves the X-axis moving mechanism 12 and the mounting head 17 to the Y-axis. Move in the direction.

  As shown in detail in FIG. 4, the mounting head 17 includes a Z-axis moving mechanism 18 that moves the suction nozzle 17a up and down in the vertical direction (Z-axis direction), and a suction nozzle and a nozzle shaft (suction shaft). As many as the number of suction nozzles (three in the illustrated example) is provided. Further, the mounting head 17 is attached with a height sensor 30 that applies laser light to the component supply device and receives the reflected light to determine the component height or the component position (component center). A component recognition camera 32 for imaging the component at the suction position is attached. A component recognition camera similar to the component recognition camera 32 is not provided with a reference numeral but is also provided on the left side.

  Further, laser mounting devices (laser recognition devices) 33 are attached to the mounting head 17 by the number of suction nozzles. As shown in detail in FIG. 1, the laser aligner 33 includes a laser emitting unit 33a that emits a laser and a laser receiving unit 33b that receives the laser from the laser emitting unit 33a. After sucking the component at the suction position from the apparatus 11, the suction nozzle descends toward the opening 33c of the laser aligner 33, and the θ-axis rotating mechanism 19 moves the suction component to θ in the laser beam from the laser light emitting unit 33a. The shaft is rotated and the shadow of the laser beam is received by the laser receiving unit 33b. An arithmetic unit (CPU) of a control unit, which will be described later, calculates a component position (component center and component inclination) by obtaining a maximum value and a minimum value of the shadow of the component received by the laser light receiving unit 33b, and adsorbs the component center The center deviation and the adsorption inclination are obtained.

  In addition, as shown in FIG. 3, the component mounting apparatus 1 is provided with a component recognition camera 16 that is fixed, and picks up the suction component from below. The picked-up image of the component is processed by an image processing unit to be described later, the component position (component center and component inclination) is calculated, and the deviation between the component center and the suction center and the suction tilt are obtained. This component recognition camera 16 is mainly used for recognizing components such as IC components that require high mounting accuracy, and the position of small components such as chip components is recognized by the laser aligner 33 described above. .

  In addition, as shown in FIG. 3, the component mounting apparatus 1 includes a CRT monitor 2 that displays component images, input data, and calculation data captured by the component recognition cameras 16 and 32, and a liquid crystal monitor that displays an operation screen. 3. A keyboard 4 for inputting commands, data and the like is provided.

  FIG. 5 shows the configuration of the control system of the component mounting apparatus 1. The component mounting apparatus 1 includes a CPU 21a that controls the entire component mounting, a ROM 21c that stores various control programs and data, and a control unit (control means) 21 that includes a RAM 21b that stores control data and processing data and provides a work area. have. Further, the component mounting apparatus 1 is provided with a data transmission / reception unit 26 capable of transmitting / receiving data to / from a host computer (not shown), and the production program transmitted from the host computer is the data transmission / reception unit 26. And is stored in the data storage unit 25. The control unit 21 uses the X / Y drive unit 22 to move the X-axis moving mechanism 12 and the Y-axis according to the production program data transmitted from the host computer and the data input via the data input unit 27 (keyboard 4 or the like). The mechanism 13 is controlled to move the mounting head 17 in the X and Y directions. Further, the control unit 21 controls the Z-axis moving mechanism 18 and the θ-axis rotating mechanism 19 by the other driving unit 23 to rotate the suction nozzle about the Z-axis direction (height direction) and the suction axis (θ). .

  Further, the control unit 21 moves the mounting head 17 in the X and Y directions on the component supply device to cross-scan the component at the suction position with the laser beam from the height sensor 30, and the CPU (calculation means) 21a The signal is taken in and the height of the part and the center position of the part are calculated. Further, the CPU 21a of the control unit 21 calculates the position (part center) of the component sucked at the suction position by obtaining the maximum value and the minimum value of the shadow of the component received by the laser light receiving unit 33b of the laser aligner 33, The position shift between the component center and the suction center and the suction inclination are obtained.

  On the other hand, the image processing unit 24 takes in the image of the component at the suction position of the component supply device captured by the component recognition camera 32 and calculates the position of the component (component center). Further, the image processing unit 24 processes the image from the component recognition camera 16 to calculate the position of the component sucked by the suction nozzle, and obtains the positional deviation between the component center and the suction center and the suction inclination. The positional deviation and suction inclination required by the component recognition camera 16 are corrected by the X-axis moving mechanism 12, the Y-axis moving mechanism 13, and the θ-axis rotating mechanism 19 while the mounting head 17 moves to the circuit board. Mounted on the circuit board 10 in a posture.

  FIG. 6 shows the configuration of the main part of the mounting head 17 according to the present invention. In FIG. 6, 19a is a θ-axis motor with a built-in motor encoder 19b, 19c is a drive pulley attached to the drive shaft of the θ-axis motor 19a, and 19d is attached to the actual drive shaft 17b of the suction nozzle 17a. The driven pulley 19e is a toothed belt stretched between the driving pulley 19c and the driven pulley 19d.

  A belt mark 19f is provided at one point on the toothed belt 19e. The belt mark 19f is, for example, a white mark drawn on the dark toothed belt 19e, and can be detected by, for example, a belt mark detection sensor 19g disposed near the actual drive shaft 17b. As the belt mark detection sensor 19g, for example, a light reflection type sensor capable of detecting the belt mark 19f can be used.

  Here, the number of teeth of the toothed belt 19e needs to be an integral multiple of the number of teeth of the driving pulley 19c and the driven pulley 19d. Further, it is desirable that the driving pulley 19c and the driven pulley 19d have the same size and the same number of teeth. In this way, the belt mark 19f is predetermined so as to make one turn when the θ-axis motor 19a rotates several times.

  In the above configuration, the correction is performed in the control unit 21 of FIG. 5 according to the procedure shown in FIG.

  That is, when the θ-axis motor 19a rotates (step 100), the belt mark 19f moves and is detected at the position of the belt mark detection sensor 19g as illustrated in FIG. 8A (step 110). Here, the rotation direction of the θ-axis motor 19a may be either positive or negative, but in this correction procedure, it is necessary to be in the same direction.

  From that position, the θ-axis motor 19a is further rotated in the same direction (step 120), and as shown in FIG. 8B, the reference position (referred to as Z-phase) output to one rotation of the motor encoder 19b. Is detected (step 130). The operating angle of the mounting head 17 is recognized for one revolution of the belt 19e itself using a jig, a laser aligner, or the like, using the Z phase immediately after the belt mark detection detected in step 130 as a reference. Specifically, the actual drive shaft 17b of the suction nozzle 17a is rotated in accordance with the motor encoder 19b, a correction value is acquired for each angle, and stored in a memory (for example, the RAM 21b in FIG. 5) (step 150). The correction value for one rotation of the belt is completed up to the next reference point (step 160), and the correction procedure is terminated.

  In this way, for example, the correction as illustrated in FIG. 9 showing the relationship between the correction values a, b, c... Recognized every 15 ° and the value (angle) of the motor encoder 19b of the θ-axis motor 19a. By collating the table or the like, an error in actual operation due to factors such as meshing between the pulleys 19c and 19d and the belt 19e is corrected. An intermediate value that is not in the correction table or the like can be obtained by interpolation calculation. FIG. 9 shows an example in which the belt makes one revolution with four rotations of the θ-axis motor and obtains a correction value every 15 °, as shown in FIG. 8, but the number of rotations of the θ-axis motor required for one revolution of the belt, The angle for obtaining the correction value is not limited to the example of FIG.

  Next, when the mounting is started, first, the origin return is performed in accordance with the procedure shown in FIG. 11 according to the command of the control unit 21 shown in FIG.

  That is, when the θ-axis motor 19a is rotated in a predetermined direction (for example, forward rotation) (step 200), the belt mark 19f moves, and the belt is detected within the detection range of the belt mark detection sensor 19g as illustrated in FIG. The mark 19f is detected (step 210). As shown by an arrow A in FIG. 11, the θ-axis motor 19a is further rotated in the same direction (eg, forward rotation) from the position (step 220), and the Z phase is adjusted by the motor encoder 19b as illustrated in FIG. 11B. Detect (step 230).

  Next, as shown by the arrow B in FIG. 11, the θ-axis motor 19a is slightly rotated in the reverse direction and returned to just before the Z phase (step 240).

  Then, as indicated by an arrow C in FIG. 11, the θ-axis motor 19a is rotated forward again at a low speed (step 250), and the return to origin is completed when the Z phase is detected (step 260).

  In this way, once the Z-phase is removed, the Z-phase at the reference point can be detected quickly and accurately by slowly rotating in the positive direction again, and accurate correction can be performed using a correction table or the like.

  In the above-described embodiment, the belt mark is drawn white on the belt, and the light reflection type belt mark detection sensor detects the belt mark. Therefore, the configuration is simple. The configuration of is not limited to this.

  In the above embodiment, since a toothed belt is used as the belt, high-precision rotation control is possible, but a belt without teeth can also be used.

  Furthermore, in the embodiment, since the incremental metal encoder built in the θ-axis motor is used as the means for detecting the rotation of the θ-axis motor, the configuration is simple and inexpensive. A separate encoder provided on the θ-axis motor side may be used.

  Further, the nozzle for picking up the component is not limited to the suction nozzle, and for example, a method of gripping the component from both sides may be used.

Diagram showing the measurement principle of the laser recognition device Perspective view showing the main configuration of the θ-axis drive mechanism The perspective view which cuts off one part which shows the whole structure of the electronic component mounting apparatus with which this invention is applied The perspective view which similarly shows the structure of a mounting head part Block diagram showing the control system The front view which shows the detailed structure of the part which concerns on this invention of the said embodiment. Flow chart showing the same correction procedure Similarly, a time chart showing an example of the relationship between the belt mark and the motor encoder Z phase The figure which similarly shows the example of a correction table Flow chart showing the procedure for returning to origin Similarly, a time chart showing the operation when returning to origin

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electronic component mounting apparatus P ... Electronic component 10 ... Circuit board 11 ... Component supply apparatus (feeder)
DESCRIPTION OF SYMBOLS 12 ... X-axis moving mechanism 13 ... Y-axis moving mechanism 17 ... Mounting head 17a ... Adsorption nozzle 17b ... Actual drive shaft 19 ... Z-axis drive mechanism 19a ... θ-axis motor 19b ... Motor encoder 19c ... Drive side pulley 19d ... Drive side pulley 19e ... toothed belt 19f ... belt mark 19g ... belt mark detection sensor 21 ... control unit 21a ... CPU
21b ... RAM
33 ... Laser alignment device (laser recognition device)

Claims (2)

A nozzle that is rotatable about an axis;
A θ-axis motor for rotating the nozzle;
A belt for transmitting the driving force of the θ-axis motor to the nozzle,
In an electronic component mounting apparatus for mounting an electronic component held by a nozzle in an electronic component supply unit on a substrate,
A belt mark attached to the belt;
A belt mark detection sensor for detecting the belt mark;
Means for correcting a rotational positional deviation between the nozzle and the θ-axis motor based on the output of the belt mark detection sensor;
An electronic component mounting apparatus comprising:   2. The electronic component mounting apparatus according to claim 1, wherein the belt is a toothed belt, and the number of teeth of the pulleys respectively attached to the nozzle and the θ-axis motor is the same.

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