Parts feeder

Abstract

To provide a part feeder capable of smoothly conveying a component along a guide groove of a stage.SOLUTION: A control part 50 of a part feeder 100 performs a feedback control on driving of a piezoelectric element 30 so that a waveform of a displacement of a stage 10 which a displacement sensor 40 detects has a sawtooth shape, and further that a waveform, in which inclination in timing when moving of the stage 10 switches from one direction to the other direction is steep and inclination before and after timing when the moving of the stage 10 switches from the other direction to the one direction is gentle, is shown, and thereby a component P can be conveyed so as to slide in the one direction along a guide groove 10a of the stage 10.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a piezoelectric parts feeder. [Background technology]

[0002] BACKGROUND ART Conventionally, there has been known a parts feeder that uses a piezoelectric element to transport an object to be transported, such as an electronic component (see, for example, Patent Document 1). This parts feeder vibrates a stage by driving a bimorph type piezoelectric element, thereby transporting electronic parts on the stage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-67360 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the case of the parts feeder of Patent Document 1, the vibration direction of the bimorph piezoelectric element is parabolic and the stage moves in an elliptical orbit, so electronic components may bounce or rotate on the stage while being transported, which can cause damage or cracks to the electronic components. In particular, when the transported object is a minute component, there are problems such as the minute component adhering to the stage and becoming unable to move, or the minute components gathering together and clumping together, blocking the transport path.

[0005] An object of the present invention is to provide a parts feeder that can smoothly transport objects such as parts. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a parts feeder, comprising: a stage having a guide groove formed on its upper surface along a predetermined direction in which the component is transported, the stage being elastically supported on a support base by an elastic member so as to be movable in the extending direction of the guide groove; a piezoelectric element disposed in contact with the stage and configured to move the stage in the predetermined direction; a displacement sensor that detects a displacement of the stage moving along the predetermined direction; Equipped with the piezoelectric element is configured to be capable of driving the stage to move at least in one direction along the predetermined direction at one speed, and to be capable of driving the stage to move at least in another direction along the predetermined direction at another speed faster than the one speed, A control unit is provided that feedback controls the drive of the piezoelectric element (expansion and contraction of the piezoelectric element) so that the waveform of the stage displacement detected by the displacement sensor exhibits a sawtooth shape, with a steep slope at the timing when the movement of the stage switches from the one direction to the other direction, and a gentle slope before and after the timing when the movement of the stage switches from the other direction to the one direction.

[0007] In a parts feeder with such a configuration, when the stage is moved in one direction at a relatively slow speed, static friction acts between the guide groove of the stage and the part, causing the part to adhere to the stage and move integrally with the stage (static friction mode; adhesion mode). On the other hand, when the stage is moved in another direction at a relatively high speed, a dynamic friction force acts between the guide groove of the stage and the part, and the part slides along the guide groove by inertia to maintain its relative position in the parts feeder, and moves relatively in one direction on the stage (dynamic friction mode; sliding mode). By repeating such static friction mode (adhesion mode) and dynamic friction mode (sliding mode), the part is transported so as to slide in one direction along the guide groove of the stage. In particular, by feedback controlling the drive of the piezoelectric element so that the waveform of the stage displacement detected by the displacement sensor exhibits a sawtooth shape, with a steep slope at the timing when the stage movement switches from one direction to the other and a gentle slope before and after the timing when the stage movement switches from the other direction to the one direction, the part can slide more smoothly along the guide groove of the stage, and the part can be transported smoothly.

[0008] Also, preferably, The elastic member is configured so that the restoring force generated when it is elastically deformed as the stage is moved in the one direction becomes a driving force for moving the stage in the other direction. With this configuration, the stage can be moved in other directions more quickly.

[0009] Also, preferably, When the stage is viewed in cross section on a plane perpendicular to the predetermined direction, the guide groove is formed so that its side surface opens upward. If the guide groove has a side surface that opens upward, the parts moving along the guide groove will not rub against the side surface, and the parts will move more smoothly.

[0010] Also, preferably, A ground is provided on the stage, and at least the guide groove is configured to prevent charging. Also, preferably, A demagnetizer is installed on the stage, and is configured so that at least the guide groove is not magnetized. Also, preferably, A heater is installed on the stage, and the stage is configured so that at least the guide groove is dry (at least no condensation occurs in the guide groove). With a stage configured in this way, parts can move smoothly along the guide grooves. [Effects of the Invention]

[0011] According to the present invention, the component can be smoothly transported along the guide groove of the stage. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a schematic top view showing the parts feeder of the present embodiment. [Figure 2] FIG. 2 is a schematic side view showing the parts feeder of the present embodiment. [Figure 3] FIG. 10 is an explanatory cross-sectional view of a guide groove provided in a stage. [Figure 4] FIG. 1(a) is an example of a control signal input to a piezoelectric element by a control unit of a parts feeder, and FIG. 1(b) is an explanatory diagram of the movement of a stage and the transportation of parts in response to the control signal. [Figure 5] 10A and 10B are explanatory diagrams relating to a control signal for driving a piezoelectric element and a response of a stage. [Figure 6] 1A shows a waveform of stage displacement in the parts feeder of this embodiment, and FIG. 1B shows a waveform of velocity and waveform of acceleration corresponding to the waveform of displacement. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of a parts feeder according to the present invention will be described in detail with reference to the drawings. However, although the embodiment described below has various limitations that are technically preferable for carrying out the present invention, the scope of the present invention is not limited to the following embodiment and illustrated examples.

[0014] As shown in Figures 1 and 2, the parts feeder 100 of this embodiment includes a stage 10 having a guide groove 10a on its upper surface that is aligned with a predetermined direction in which parts P are transported, an elastic member 20 that elastically supports the stage 10 on a support base B so that the stage 10 can move in the extension direction of the guide groove 10a, a piezoelectric element 30 that moves the stage 10 in the predetermined direction, a displacement sensor 40 that detects the displacement of the stage 10 moving in the predetermined direction, and a control unit 50 that feedback-controls the drive of the piezoelectric element 30 in accordance with the displacement of the stage 10 detected by the displacement sensor 40. The parts P conveyed by the parts feeder 100 are, for example, minute parts measuring 0.2 mm square and 0.4 mm long (04×02), or minute parts measuring 0.1 mm square and 0.2 mm long (02×01).

[0015] The stage 10 is, for example, a flat metal member, and has a guide groove 10a formed on the top surface thereof along a predetermined direction. When this stage 10 is viewed in cross section on a plane perpendicular to a predetermined direction, the guide groove 10a is formed so that the side surface of the guide groove 10a opens upward, as shown in FIG. If the side surface of the guide groove 10a is open upward, the component P moving along the guide groove 10a will not rub against the side surface, and the component will move more smoothly.

[0016] The elastic members 20 are, for example, leaf springs that are substantially L-shaped when viewed from above, and are provided at the four corners of the stage 10. One end of a substantially L-shaped elastic member 20 is fixed to the stage 10, and the other end is fixed to the support base B. One end of this elastic member 20 is the portion that undergoes elastic deformation. The elastic member 20 elastically supports the stage 10 on the support base B so that the stage 10 can move in a substantially horizontal direction.

[0017] The piezoelectric element 30 is fixed on a support base B, and the drive section of the piezoelectric element 30 is disposed in contact with one side surface of the stage 10 (the left side surface in the drawing). Lead wires for applying a voltage are connected to the piezoelectric element 30, and when a voltage is applied to the piezoelectric element 30, the piezoelectric element 30 expands. The expanded piezoelectric element 30 moves the stage 10 in one direction (to the right in the figure) as if pushing it out, and the contracted piezoelectric element 30 moves the stage 10 in the other direction (to the left in the figure) as if pulling it back. This piezoelectric element 30 is configured to be capable of driving the stage 10 to move in one direction along a predetermined direction (to the right in the figure) at one speed, and to drive the stage 10 to move in another direction along the predetermined direction (to the left in the figure) at another speed that is faster than the one speed.

[0018] In addition, the elastic member 30 is configured so that the restoring force generated when the elastic member 30, which has been elastically deformed as the stage 10 is moved in one direction by the piezoelectric element 30, restores to its original shape and becomes a driving force that moves the stage 10 in the other direction (leftward in the figure).

[0019] The stage 10 is designed so that its center of gravity is on the line of action L along which the piezoelectric element 30 exerts a driving force to move the stage 10, and the piezoelectric element 30 and the stage 10 are placed on a support base B. By adopting such a structure, the movement of the stage 10 can be stabilized.

[0020] The displacement sensor 40 is fixed on the support base B, and is disposed at a position spaced apart from the stage 10 on the other side of the stage 10 (the right side in the drawing). That is, the piezoelectric element 30 and the displacement sensor 40 are arranged opposite to each other with the stage 10 interposed therebetween. The displacement sensor 40 is, for example, a capacitance type displacement sensor, and detects the displacement of the stage 10 which moves in the horizontal direction when driven by the piezoelectric element 30 . The displacement sensor 40 here detects the displacement of the stage 10 as it approaches or moves away from the displacement sensor 40 .

[0021] The control unit 50 includes, for example, a CPU, a ROM, a RAM, and the like, and is a controller that controls each unit in cooperation with the CPU and program data stored in the ROM expanded in the working area of ​​the RAM. 2, the control unit 50 is connected to the displacement sensor 40 via a displacement sensor amplifier 41. The control unit 50 is also connected to the piezoelectric element 30 via a piezo driver 31. As will be described later, the control unit 50 of the parts feeder 100 of this embodiment is configured to feedback control the drive of the piezoelectric element 30 so that the waveform of the displacement of the stage 10 detected by the displacement sensor 40 exhibits a sawtooth shape, with a steep slope at the timing when the movement of the stage 10 switches from one direction to the other, and a gentle slope before and after the timing when the movement of the stage 10 switches from the other direction to the one direction.

[0022] Next, the conveyance of the parts P by the parts feeder 100 of this embodiment will be described.

[0023] For example, based on a command from an external higher-level control device, a control signal having the waveform shown in Figure 4(a) is input to the control unit 50, and a voltage according to the command value of the control signal is applied to the piezoelectric element 30 via the piezo driver 31. As shown in FIG. 4(b), the piezoelectric element 30 to which a voltage corresponding to this control signal is applied moves the stage 10 in one direction (to the right in the figure) at one speed ((1)-(2)), then moves the stage 10 in the other direction (to the left in the figure) at another speed faster than the one speed ((2)-(3)), and then moves the stage 10 in the one direction at one speed ((3)-(4)), and then moves the stage 10 in the other direction at another speed faster than the one speed ((4)-(5)).

[0024] When the stage 10 moves in one direction (to the right in the figure) at a relatively slow speed ((1)-(2), (3)-(4)), a static friction force acts between the guide groove 10a of the stage 10 and the part P, and the part P moves integrally with the stage 10 (static friction mode; adhesion mode). On the other hand, when the stage 10 moves in another direction (leftward in the figure) at a relatively high speed ((2)-(3), (4)-(5)), a dynamic friction force acts between the guide groove 10a of the stage 10 and the part P, and the part P slides along the guide groove 10a by inertia to maintain its relative position in the part feeder 100, and moves relatively in one direction on the stage 10 (dynamic friction mode; sliding mode). In other words, by inputting a control signal having such a waveform (Figure 4(a)) into the control unit 50 and driving the piezoelectric element 30 to expand and contract, a static friction mode (adhesion mode) is repeated in which the stage 10 moves in one direction at one speed (low speed) where a static friction force acts between the guide groove 10a of the stage 10 and the part P, and a kinetic friction mode (sliding mode) is repeated in which the stage 10 moves in the other direction at another speed (high speed) where a kinetic friction force acts between the guide groove 10a of the stage 10 and the part P. By repeating the static friction mode and the dynamic friction mode, the part P is conveyed along the guide groove 10a on the stage 10 so as to slide in one direction (to the right in the drawing).

[0025] In addition, when the waveform of the control signal is a sawtooth waveform as shown in Figure 4(a), the waveform of the displacement of the stage 10 moved by the piezoelectric element 30 to which a voltage corresponding to the command value of the control signal is applied is detected by the displacement sensor 40 as a sawtooth waveform similar to the waveform of the control signal.

[0026] Incidentally, when the stage 10 is moved in one direction by the piezoelectric element 30 to which a voltage corresponding to the command value of the control signal is applied, if the speed (acceleration) at which the piezoelectric element 30 expands is large, this may cause an impact and generate a natural vibration in the stage 10 (see the upper part of Figure 5). If such natural vibration occurs, the part P may bounce off the stage 10 and become unable to move together with the stage 10. For example, if such natural vibration occurs, the movement of the stage 10 will deviate from that based on the control signal, and the transportation of the part P will become uneven. Therefore, the generation of natural vibration of the stage 10 is suppressed by feedback-controlling the drive of the piezoelectric element 30 (see the bottom part of Figure 5). In particular, when the stage 10 is moved in one direction after having been moved in another direction, the sudden change in the direction of movement is likely to cause an impact, which will cause natural vibrations in the stage 10. Therefore, the drive of the piezoelectric element 30 is feedback-controlled to suppress the occurrence of natural vibrations in the stage 10. Furthermore, the control unit 50 is provided with a notch filter circuit, and the natural vibration of the stage 10 can also be suppressed by waveform control using the notch filter.

[0027] Next, with regard to the conveyance of the parts P by the parts feeder 100 of this embodiment, feedback control of the drive of the piezoelectric element 30 will be described with reference to FIG. 6(a). In FIG. 6(a), one waveform of the sawtooth waveform is shown as the waveform of the displacement of the stage 10, but this waveform is repeated to form the sawtooth waveform.

[0028] As mentioned above, when the stage 10 is moved in one direction by the piezoelectric element 30 to which voltage is applied, if the speed (acceleration) at which the piezoelectric element 30 expands is large, this can cause an impact and result in natural vibration of the stage 10. In order to prevent this natural vibration from occurring, it is preferable to reduce the magnitude of the acceleration of the stage 10 before and after the timing at which the stage 10 switches from a dynamic friction mode in which the stage 10 moves in another direction to a static friction mode in which the stage 10 moves in one direction (for example, the acceleration at the timings (iv) and (b) in Figure 6). Therefore, in this embodiment, the driving of the piezoelectric element 30 is controlled so that the stage 10 moves relatively slowly at the timing when the dynamic friction mode ends (timing (d)-(e) in FIG. 6(a)) and the timing when the static friction mode starts (timing (a)-(b) in FIG. 6(a)). Specifically, the control unit 50 is provided with a function for editing the control waveform so as to reduce the magnitude of the acceleration of the stage 10 .

[0029] To this end, the control unit 50 feedback-controls the drive of the piezoelectric element 30 so that the slope of the displacement waveform becomes gentle when the movement of the stage 10 switches from another direction (dynamic friction mode) to one direction (static friction mode) ((d)-(e), (a)-(b) in Figure 6(a)). Specifically, the control waveform is edited and the drive of the piezoelectric element 30 is feedback-controlled so that the slope of the displacement waveform in the latter half of the dynamic friction mode ((d)-(e) in FIG. 6(a)) is gentler than the slope of the displacement waveform in the first half of the dynamic friction mode ((c)-(d) in FIG. 6(a)), and the slope of the displacement waveform at the beginning of the static friction mode ((a)-(b) in FIG. 6(a)) is gentler than the slope of the displacement waveform in the subsequent static friction mode ((b)-(c) in FIG. 6(a)).

[0030] Furthermore, in order to clearly switch from the static friction mode to the dynamic friction mode, it is preferable to move the stage 10 with a sudden change in speed in the opposite direction. In other words, it is preferable to move the stage 10 with a large acceleration that instantaneously reverses the direction. Therefore, in this embodiment, at the timing when the static friction mode is switched to the dynamic friction mode (timing (c) in Figure 6(a)), the driving of the piezoelectric element 30 is controlled so that the stage 10 suddenly changes direction from one direction to another and moves at high speed.

[0031] To this end, the control unit 50 feedback-controls the drive of the piezoelectric element 30 so that the slope of the displacement waveform becomes steep when the movement of the stage 10 switches from one direction (static friction mode) to another direction (dynamic friction mode) ((c) in Figure 6(a)). Specifically, the control waveform is edited so that the gradient of the waveform of the displacement at the beginning of the dynamic friction mode ((c) in FIG. 6(a)) becomes approximately vertical, and the drive of the piezoelectric element 30 is feedback-controlled. More specifically, the control waveform is adjusted so that the slope of the displacement waveform becomes steep (high acceleration) when the movement of the stage 10 switches from one direction (static friction mode) to another direction (dynamic friction mode) ((c) in Figure 6(a)). At that time, the control waveform is edited while referring to the magnitude of the stage acceleration signal. The acceleration signal is generated by processing the displacement sensor signal. Here, the control waveform is edited so that the slope of the waveform of the displacement at the beginning of the dynamic friction mode ((c) in FIG. 6(a)) becomes approximately vertical.

[0032] In other words, in this embodiment, feedback control is performed using the displacement sensor 40 so that the stage 10 moves according to the control signal, and the control signal is edited while referring to the acceleration signal of the stage 10 in order to suitably switch between static friction mode (adhesion mode) and dynamic friction mode (slip mode).

[0033] Then, by feedback-controlling the drive of the piezoelectric element 30 so that the waveform of the displacement of the stage 10 detected by the displacement sensor 40 exhibits the waveform shown by the solid line in Figure 6(a), it is possible to suitably switch between static friction mode and dynamic friction mode, and to suitably transport the part P along the guide groove 10a of the stage 10. (The waveform shown by the dashed line in Figure 6(a) is the same as the model waveform shown in Figure 4(a).) When the drive of the piezoelectric element 30 is feedback-controlled so that the waveform of the displacement of the stage 10 detected by the displacement sensor 40 exhibits the waveform of the solid line shown in FIG. 6(a), it can be said that an external higher-level control device inputs a control signal similar to the waveform of the solid line shown in FIG. 6(a) to the control unit 50, and applies a voltage according to the command value of the control signal to the piezoelectric element 30 via the piezo driver 31, thereby moving the stage 10. In addition, the control unit 50 may internally store multiple pieces of control signal waveform pattern information similar to the solid line waveform shown in Figure 6(a), and an external higher-level control device may select a waveform pattern, switch the waveform output ON / OFF, and output a waveform output timing signal (repetition frequency) to move the stage 10.

[0034] In this way, by feedback-controlling the drive of the piezoelectric element 30 so that the waveform of the displacement of the stage 10 detected by the displacement sensor 40 is not a simple sawtooth waveform (the waveform shown by the dashed line in FIG. 6(a)), but rather the solid line waveform shown in FIG. 6(a), the part P can be transported by sliding it in one direction (to the right in the figure) along the guide groove 10a on the stage 10. In other words, the component P on the stage 10 is not transported in a bouncing manner, and therefore the component P being transported does not suffer from defects such as breakage. In particular, if the part P being transported by the part feeder 100 is a tiny part, the part P may bounce due to slight vibrations, but the part feeder 100 of this embodiment can suitably switch between static friction mode and dynamic friction mode, allowing even tiny parts P to be transported by sliding them across the stage 10.

[0035] It should be noted that by using a control signal in a form in which the control waveform of the control signal shown in FIG. 6(a) is inverted, the conveying direction of the part P being moved on the stage 10 can be reversed. For example, by moving the stage 10 in another direction (left direction in the figure) at a relatively slow speed (static friction mode; adhesion mode), and then moving the stage 10 in one direction (right direction in the figure) at a relatively high speed (dynamic friction mode; sliding mode), the conveying direction can be switched so that the part P on the stage 10 moves in the other direction. If the conveying direction of the parts P can be switched to the opposite direction, when multiple parts P become clogged in the guide groove 10a, the control signal (control waveform) can be switched to temporarily reverse the conveying direction of the parts P, thereby clearing the clog.

[0036] The present invention is not limited to the above embodiment. For example, a ground (not shown) may be installed on the stage 10. If the guide groove 10a is configured so that it is not charged by the ground, the movement of the component P along the guide groove 10a will be smooth, which is preferable.

[0037] In addition, a demagnetizer (not shown) may be installed on the stage 10. If the guide groove 10a is configured so as not to be magnetized by the demagnetizer, it is preferable because the movement of the part P along the guide groove 10a becomes smoother.

[0038] In addition, a heater (not shown) may be installed on the stage 10. It is preferable to use the heater to heat the guide groove 10a (stage 10) and evaporate moisture from the surface of the guide groove 10a so that the guide groove 10a is dry, as this allows the part P to move smoothly along the guide groove 10a. Furthermore, if the heater is configured to make the temperature of the guide groove 10a approximately the same as the temperature in the room where the parts feeder 100 is installed, thereby preventing condensation from forming in the guide groove 10a, this is preferable as it allows the parts P to move smoothly along the guide groove 10a.

[0039] In order to prevent charging, static electricity, and magnetism, the stage 10 may be made of a non-magnetic material such as ceramics.

[0040] The application of the present invention is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the present invention. [Explanation of symbols]

[0041] 10 stages 10a Guide groove 20 Elastic member 30 Piezoelectric element 40 Displacement Sensor 50 control section 100 parts feeder B Support stand P parts L line of action

Claims

1. a stage having a guide groove formed on its upper surface along a predetermined direction in which the component is transported, the stage being elastically supported on a support base by an elastic member so as to be movable in the extending direction of the guide groove; a piezoelectric element disposed in contact with the stage and configured to move the stage in the predetermined direction; a displacement sensor that detects a displacement of the stage moving along the predetermined direction; Equipped with the piezoelectric element is configured to be capable of driving the stage to move at least in one direction along the predetermined direction at one speed, and to be capable of driving the stage to move at least in another direction along the predetermined direction at another speed faster than the one speed, a control unit that feedback-controls the drive of the piezoelectric element so that the waveform of the displacement of the stage detected by the displacement sensor exhibits a sawtooth shape, with a steep slope at the timing when the movement of the stage switches from the one direction to the other direction, and a gentle slope before and after the timing when the movement of the stage switches from the other direction to the one direction.

2. 2. The parts feeder according to claim 1, wherein the restoring force of the elastic member, which is elastically deformed as the stage is moved in the one direction, when the elastic member is restored, serves as a driving force for moving the stage in the other direction.

3. 3. A parts feeder according to claim 1, wherein the guide groove is formed so that its side faces open upward when the stage is viewed in cross section on a plane perpendicular to the predetermined direction.

4. 3. The parts feeder according to claim 1, wherein a ground is provided on the stage, and at least the guide groove is configured to prevent charging.

5. 3. The parts feeder according to claim 1, wherein a demagnetizer is provided on the stage, so that at least the guide groove is demagnetized.

6. 3. The parts feeder according to claim 1, wherein a heater is provided on the stage, and at least the guide groove is kept dry.

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