JP3510912B2 - Head drive mechanism - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a head portion for sucking an IC chip component from a component supply portion by vacuum pressure and mounting the chip component on a substrate or a head portion of an XY plotter. The present invention relates to a head drive mechanism that drives in the -Y direction.

[0002]

2. Description of the Related Art Conventionally known head drive mechanisms for mounting IC chips are shown in FIGS.

In FIG. 3, an IC chip component suction mounting head 10 sucks an IC chip component at its lower end, moves it in the X direction (sub-axis direction) and Y direction (main axis direction), and then mounts it on a substrate. Is.

The head 10 is slidably mounted on a linear motion bearing rail 11 for moving the head 10 in the X direction. Further, both ends of the rail 11 are fixed to a support body, that is, a sub shaft 12 supported by receiving portions 13A and 13B, respectively. The motor 14 attached to the counter shaft 12 serves to move the head 10 in the X direction along the rail 11 via a belt (not shown).

The receiving portions 13A and 13B are linear motion bearing rails, that is, linear motion guide bearings fixed to a pair of main shaft base portions 19A and 19B extending in the Y direction orthogonal to the rail 11 extending in the X direction. It is supported by 15A and 15B. The receiving portions 13A and 13B are driven by a drive belt 16 which is controlled and driven by a main shaft driving servomotor 17 and a rotary encoder 18 which are fixed to a frame, and are moved in the Y direction on the rails 15A and 15B. In this conventional example, the rotation of the motors 14 and 17 is converted into a linear motion by a belt, but linear driving by a ball screw is also widely known.

However, as described above, one spindle base portion 19
In the device for controlling the drive of the auxiliary shaft 12 on the A side, a large moment caused by the mass of the auxiliary shaft itself is applied to the auxiliary shaft drive portion provided at the end of the auxiliary shaft for driving the auxiliary shaft, and thus the auxiliary shaft 12 is driven. A problem of damping (vibration convergence) occurs with respect to the movement of the shaft. In order to solve such a problem, a high-rigidity spindle and counter-spindle unit is required, and a large-capacity drive motor must be used. However, this makes operation at high speeds difficult. Further, if a ball screw is used to prevent damping, the lead of the ball screw becomes large, and there is a drawback that it is difficult to increase the speed substantially.

In other words, in the conventional example of FIG. 3, only one end of the long rod-shaped counter shaft 12 is driven, and the other end is guided by the linear motion bearing, so to speak, it has a cantilever structure. Therefore, vibration is likely to occur when the motor 17 is driven in the Y direction, particularly when the motor 17 is stopped, and the vibration convergence time (damping time) for converging the vibration becomes long.

By the way, in general, a chip mounter needs to produce a substrate at a high speed, so that it is necessary to move the head in the X and Y directions at a high speed. On the other hand, in recent years, the shape of IC chip components to be mounted has been downsized, and it is required that the accuracy when mounting the chip on the substrate be within several tens of microns.

When the head 10 is moved at a high speed in the Y direction in the apparatus shown in FIG. 3, the acceleration applied to the counter shaft 12 is increased and natural vibration is generated. When the chip component is mounted immediately after the movement in the Y direction is stopped, the head is vibrating, so that the chip component cannot be mounted with desired accuracy. If the vibration is converged, it makes no sense to drive the corner support at a high speed. Further, if the rigidity of the sub shaft 12 is increased to prevent vibration, the natural frequency increases, and the convergence speeds up, but the increase in rigidity accompanies an increase in weight and requires an increase in the output of the servo motor 17. Generally, when the output of the servo motor increases, the rotor diameter of the servo motor increases, the angular moment of inertia increases, and eventually it becomes disadvantageous for high acceleration drive.

In order to solve such a problem, the driving force is transmitted from the servo motor and the rotary encoder fixed to one main spindle base portion to the other main spindle base portion by using a belt or a fixed rotary shaft such as a ball screw. A device that drives both ends of the counter shaft at the same time has been announced.
However, in such a device, a pitch error and a transmission delay occur in the transmission device, so that it is difficult to perform highly accurate position control and high-speed operation.

In order to solve these problems, a device as shown in FIG. 4 has also been announced. The conventional example of FIG. 4 is different from the conventional example of FIG. 3 in that, in FIG. 3, the spindle drive servomotor 17 and the rotary encoder 18 for driving in the Y direction are shown.
4 is used only for one of the main shaft base portions 19A to drive only one side of the sub shaft 12, but in the conventional example of FIG. 4, the belt 16B, the servo motor 17B and the rotary shaft are driven to drive both sides of the sub shaft 12 at the same time. The encoder 18B is also provided on the other spindle base portion 19B. This improves the accuracy of the stop position of the head 10 in the Y direction.

[0012]

However, the conventional apparatus shown in FIG. 4 has various problems to be solved as follows.

That is, since both ends of the counter shaft 12 are simultaneously driven, the load amount per servo motor is reduced, and the natural frequency is greatly increased. Most of the drawbacks of the conventional example device of FIG. It has been resolved, since the countershaft 12 is using ordinary servomotor 17 a, 17B for high-speed movement, when a combination of these servo motors to the drive unit, the servo characteristics of the individual motors are usually Unlike the difference of the motor inertia load and viscous load, the same command pulse rate in both the servo motors 17 a, can give an instruction to 17B, the command pulses and the encoder 18 a, the difference viz cumulative pulse feedback pulses from 18B sometimes it would by no means be that match <br/> than, one end of the sub-shaft is advanced ahead from the other end. As a result, the two motors interfere with each other to generate violent vibration, and smooth movement may not be obtained.

Further, both the main shaft and the sub shaft of FIG. 3, the both main shafts and the sub shafts of FIG. 4, both ends of the loop belt are held by pulleys,
One of the two pulleys is connected to the motor and the other is driven, but the larger the acceleration of the XY movement, the larger the output of the motor,
Generally, in order to increase the output, the rotor diameter inside the motor must be increased, resulting in an increase in the angular moment of inertia of the motor itself. Therefore, even if the motor is driven at a high acceleration, the output energy is consumed for the rotation of the motor itself, and even if a large output motor is used, the substantial acceleration cannot be increased.

The present invention has been made in view of the above-mentioned conventional problems, and it is possible to increase the moving speed of the head portion without using a high-power motor, and to improve the positioning accuracy and the tact time. It is an object of the present invention to provide a head drive mechanism capable of performing the above.

[0016]

According to the invention of claim 1, a counter shaft is provided.
A head portion drive mechanism that includes a unit and that includes a sub-axis direction drive mechanism that drives the head portion in the sub-axis direction and a main-axis direction drive mechanism that drives the head portion in a main axis direction orthogonal to the sub-axis direction. A pair of belts for independently driving both ends of the auxiliary shaft unit, a servomotor for independently driving these belts, and a moving speed of both ends of the auxiliary shaft unit. And a linear encoder that detects at least one of the movement amounts, and two servo motors are installed on the pulleys of at least one of the pair of belts, and the linear encoder and the servo motor are It is arranged so as to be controlled by a full closed loop to achieve the above object.

Further, as in claim 2, wherein the auxiliary axially drive mechanism, said countershaft unit for supporting the head portion, and a belt for driving along the head portion in the longitudinal direction of the sub axis unit, this Sub-axis that is a servo motor that drives the belt
A drive motor, and configured to include, the auxiliary shaft drive motor,
Two units may be installed on the pulley at the end of the belt that drives the head unit .

[0018]

[0019]

Operation: Linear encoders attached to a pair of main spindle base portions that support both ends of the sub shaft respectively drive the sub shaft end portions by a main shaft drive servomotor and a drive belt that drive both ends of the sub shaft. Detects speed, feed pitch, etc. Then, a linear encoder in which the position of the sub-axis is further arranged detects the driving speed, and controls the servo motor so that these values are always the same on the left and right sides.

[0020]

EXAMPLES Examples of the present invention shown in FIGS. 1 and 2 will be described below. This is an improvement of the conventional head drive mechanism shown in FIGS. 3 and 4, and in FIG.
This is a chip component suction mounting head that mounts this on a substrate (not shown) after moving in the direction. This head 20
Is slidably mounted on a linear motion bearing rail (not shown) mounted on the counter shaft unit 22. In addition, the auxiliary shaft drive motor 24 is provided on both sides of the auxiliary shaft unit 22.
A and 24B are placed. These motors 24A,
Belt drive pulleys 26A, 2 driven by 24B
A belt 25 is attached to 6B. The head 20 is fixed to the belt 25, and the motors 24A, 24
The rotation of B allows the head 20 to move quickly in the X direction.

Both ends of the sub shaft unit 22 are main shaft base portions 27A, 27 arranged on both sides of a substrate (not shown).
Linear guide bearing 28A mounted on the upper surface of B,
28B is movably received on these linear motion guide bearings 28A and 28B.
Further, the auxiliary shaft unit 22 has a main shaft base portion 27 from both ends thereof.
It has a pair of counter shaft drive connecting plates 29A and 29B which hang down along A and 27B. This connecting plate 29A, 29
B is fixed to belts 30A and 30B that reciprocate in the Y direction. The belts 30A and 30B are driven between a pair of belt drive pulleys 32A, 33A and 32B and 33B by spindle drive servomotors 31A to 31D fixed to the spindle base portions 27A and 27B, respectively.

Further, linear encoders 35A and 35B are attached to the sides of the spindle base portions 27A and 27B. The linear encoders 35A and 35B are composed of a scale that has been subjected to optical etching or magnetic treatment as is well known, and a detector.

Here, as shown in FIG. 2, the servomotors 31A to 31D have CPUs in the apparatus based on preset values for the spindle movement distance and the spindle movement speed.
When a predetermined command is issued via (not shown), the command is simultaneously sent to the spindle servo drivers 41A to 41D, signals from these spindle servo drivers 41A to 41D enter, and both belts 30A and 30B rotate simultaneously. It moves so as to start driving both ends of the sub shaft unit 22 at the same time.

At this time, the moving distance and moving speed of the sub-axis unit 22 in the main-axis direction are determined by the linear encoders 35A and 35A.
B accurately senses through the same means as the connecting plate 29, and then, through a known servo mechanism, the two spindle side drive circuits are made into a full closed loop as shown in FIG. The signal is repeatedly fed back to 41A to 41D.

As a result, the pitch error of the belts 30A and 30B is eliminated, the positioning accuracy of the auxiliary shaft unit 22 is improved, and mutual interference between both motors as in the case of the device of FIG. It is possible to reduce the load and increase the speed. As a result, two independent motor belts of the two main shafts can be made to have the same positional relationship, and the damping characteristics of the belts can be made equal to each other, whereby the positioning accuracy and the tact can be significantly improved.

In the embodiment described here, an example in which the linear encoders 35A and 35B sense both the rotational speed (speed) and the position of the auxiliary shaft unit 22 has been described. However, the linear encoders 35A and 35B are
Sensing only two positions, whereas the rotary encoder 18A shown in FIG. 4, the same rotary encoder and 18B 1
It is also possible to attach the servo motors 31A and 31B so as to interlock with each other, detect the rotation speed of the servo motor by this rotary encoder, send these signals to the servo motor, and perform feedback control with each other.

It is also possible to connect the motors to both pulleys only to the one having a large load on the main shaft and the auxiliary shaft, and to connect the motor to only one pulley on the one having a small load. Further, when two servo motors are provided, one pulley is provided at each end of the belt in the embodiment, but two servo motors may be provided at one pulley.

Although the chip mounter has been described in the above embodiment, the present invention can be applied to other devices such as a plotter which moves the head in the XY directions.

[0029]

According to the present invention, since two motors are attached to the pulleys of at least one of the belts of both spindles, the load on each motor is reduced, so that a high-power motor is required. As a result, the angular moment of inertia of the motor itself is reduced and high acceleration operation is possible, and the use of a pair of linear encoders makes it possible to make the two motor belts independent of the two main shafts have the same positional relationship. By equalizing the damping characteristics by
Positioning accuracy and tact can be significantly improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of a head drive mechanism according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the operation of the head drive mechanism of the embodiment.

FIG. 3 is a perspective view showing a known head drive mechanism.

FIG. 4 is a perspective view showing another known head drive mechanism.

[Explanation of symbols]

20 ... Chip component suction mounting head 22 ... Secondary shaft units 24A, 24B ... Secondary shaft drive motors 25, 30A, 30B ... Belts 26A, 26B, 32A, 32B, 33A, 33B ... Belt drive pulleys 27A, 27B ... Spindle base portion 31A ~ 31D ... Spindle drive servomotors 35A, 35B ... Linear encoder

Continuation of the front page (56) Reference JP-A-3-203294 (JP, A) JP-A-3-218097 (JP, A) JP-A-62-37988 (JP, A) JP-A-3-9599 (JP , A) JP-A-4-10600 (JP, A) JP-A-4-223960 (JP, A) JP-A-4-322982 (JP, A) JP-A-3-268485 (JP, A) 3-92100 (JP, U) Tokuyo Hyo 6-505862 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H05K 13/04

Claims (2)

(57) [Claims] 1. A sub-axis direction drive mechanism that includes a sub-axis unit and that drives a head section in the sub-axis direction, and a main-axis direction drive mechanism that drives the head section in a main axis direction orthogonal to the sub-axis direction. A head drive mechanism comprising: a pair of belts for independently driving both ends of the auxiliary shaft unit, a servomotor for independently driving these belts, and the auxiliary shaft for the main shaft direction drive mechanism. A linear encoder that detects at least one of the moving speed and the moving amount of both ends of the unit, and two servo motors are installed on a pulley of at least one of the pair of belts. A head drive mechanism characterized in that a linear encoder and a servomotor are arranged so as to be controlled by a full-closed loop. 2. A sub-axial unit for supporting a head portion of the sub-axial direction drive mechanism, a belt for driving the head portion along a longitudinal direction of the sub-axial unit, and the belt according to claim 1. And a sub-axis drive motor that is a servo motor for driving the sub-axis drive motor. Two sub-axis drive motors are installed on a pulley at the end of the belt that drives the head section. mechanism.