JP5262390B2 - Particle transport equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a particle transport device, capable of transporting particles with high efficiency by eliminating a singular point at which the particles stay. <P>SOLUTION: The pattern of an application voltage to linear electrodes formed on a substrate is periodically and intermittently switched with the lapse of time. For example, among sine wave alternating voltages of 6 phases, the voltages of some phases are switched to the voltages of other phases at times of u=5, 10, and 15 of repetition of times u=1 to 15. According to this, particles can be transported with high efficiency without causing the singular point at which the particles stay on the arrangement space of the linear electrodes. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a particle transport device for electrically transporting particles.

  Patent Document 1 discloses a particle transport device that moves particles by generating a Coulomb force by applying a multiphase voltage to an electrode portion.

Here, the configuration of the particle transport device of Patent Document 1 will be described with reference to FIGS. 1 and 2.
1 is a perspective view thereof, and FIG. 2 is a side view thereof. As shown in FIGS. 1 and 2, a plurality of linear electrodes 3 are arranged in parallel in an insulator 2 to form a flat stator 1, and an alternating voltage is applied to the linear electrodes 3 by a power source 9. Thus, a Coulomb force is generated in the vicinity of the linear electrode 3, and the particles 29 on the flat stator 1 are transported while being attracted to the surface of the flat stator 1.
Japanese Patent No. 3567544

  However, in the particle transport device disclosed in Patent Document 1, the inventors have experimentally found that a problem that some particles on the flat stator 1 cannot be transported while adhering to a fixed position may occur. And theoretically discovered.

  Particles are transported by applying alternating voltages of multiple phases to linear electrodes arranged in parallel. The forward and backward Coulomb forces generated in the particles are balanced between the adjacent linear electrodes. This is because the stable equilibrium position (stable point) sequentially moves according to the voltage change of each phase, and the particles move accordingly.

However, when the applied voltage of each phase is a sine wave AC voltage with a constant frequency and the phases have the same phase difference, the particles can be removed from the stable point even if the drive voltage changes over time. A position (singular point) where a sufficiently large Coulomb force necessary to move to the next stable point adjacent thereto does not act is generated. The particles at such a position will stay without moving from there.
This will become clearer in comparison with the prior art described in the embodiments of the present invention described below.

  An object of the present invention is to provide a particle transport device that can transport particles with high efficiency without causing a singular point where the particles stay.

The particle transport device of the present invention is configured as follows.
(1) linear electrodes arranged parallel or substantially parallel to each other;
The arrangement order number of the linear electrodes is represented by k (k is an integer starting from 0), the number of phases that can be taken by the periodically changing driving voltage to be applied to the linear electrodes is represented by n , and the remainder function is represented by In terms of Mod,
p = Mod (k, n) +1
A voltage applying means for applying a p-phase driving voltage represented by the following to the linear electrodes of the array sequence number k:
The driving voltage is an alternating voltage of the n-phase, the voltage applying means, by selecting one of the phases of the alternating voltage of the n-phase with time, the pattern of the voltage applied to the linear electrodes the assumed that you switch discontinuously over time.

The above-mentioned singular point is caused by the fact that the applied voltage pattern to the linear electrodes on the arrangement space of the linear electrodes is constant in translational symmetry. The point is temporarily eliminated, and the particles temporarily staying at the singular point start moving again, so that the stay of particles can be suppressed and highly efficient particle transportation can be realized.
In addition, since it can be driven by simple waveform switching, the circuit configuration is not complicated and drive control is facilitated.

( 2 ) The plurality of linear electrodes are arranged on a dielectric or insulating substrate, and an insulating film is coated on the linear electrodes.
With this configuration, discharge between electrodes and discharge from the electrodes can be suppressed, and oxidation of the electrodes can be suppressed, so that stable characteristics can be maintained over a long period of time.

  According to the present invention, a singular point is not generated or hardly generated, particle retention can be suppressed, and highly efficient particle transportation can be realized.

<< First Embodiment >>
A particle transport device according to a first embodiment of the present invention will be described with reference to FIGS.
FIG. 3 is a diagram showing a configuration of a plurality of linear electrodes and a power source for applying a voltage to them, and FIG. 3 (A) is a plan view of a dielectric substrate on which linear electrodes are formed, and FIG. 3 (B). Is a side view thereof.

  A plurality of linear electrodes 52 are arranged in parallel and at regular intervals on the upper surface of the dielectric substrate 51, and further, an arrayed electrode substrate portion 50 is formed by covering an insulating cover coat 54. The AC power supply unit 40 outputs six-phase drive voltages from the output terminals V1 to V6. The linear electrodes 52 are connected in parallel to the connection portions 53 every six in the arrangement order, and are connected to output terminals V1 to V6 of the AC power supply portion described later.

  In FIG. 3 (B), the linear electrodes 52 are respectively linear electrodes E1 (1), E2 (1), E3 (1), E4 (1), E5 (1), E6 (1), E1 (2). , E2 (2), E3 (2), E4 (2), E5 (2), E6 (2), E1 (3), E2 (3), E3 (3), E4 (3), E5 (3) , E6 (3).

  In addition, by covering the linear electrode 52 with the insulating cover coat 54, the linear electrode 52 can be protected from corrosion and oxidation due to corrosive gas, oxygen, moisture, etc., and spark discharge can be prevented. Further, charging of the particles can be prevented, and the particles can be transported stably. Moreover, since the site | part with a remarkably large electric field is not exposed, particle | grain crushing can be prevented.

  FIG. 4 is a cross-sectional view of the particle transport device according to the first embodiment of the present invention, which is specifically used to specifically determine the force applied to the particles moving along the arrayed electrode substrate portion 50 by the method described later. The typical dimensions are also shown.

  FIG. 5 is a block diagram showing the configuration of the AC power supply unit. FIG. 5A is a block diagram of the entire particle transport device, and FIG. 5B is a block diagram showing the configuration of the AC power supply unit 40. In FIG. 5A, the array electrode substrate section 50 includes the dielectric substrate 51 shown in FIG. 3, the linear electrodes 52 formed thereon, and the connection sections 53 that connect them in parallel at a predetermined interval.

  As shown in FIG. 5B, the AC power supply unit 40 includes a six-phase AC voltage source 42, a switching circuit 43, and a clock generation circuit 41. The clock generation circuit 41 generates a clock signal CLK that serves as a reference timing for the switching pattern control circuit 44.

  The switching pattern control circuit 44 selects which of the alternating voltages X1 to X6 generated by the six-phase alternating voltage source 42 to be output to the output terminals V1 to V6 according to a switching pattern table to be described later. P6 is generated.

  Each of the AC voltages X1 to X6 is a sine wave AC voltage of 600 Vpp.

  The 6-phase AC voltage source 42 shown in FIG. 5 includes sinusoidal voltage outputs X1 to X6 that are different in phase by 60 degrees in phase order, for example. The instantaneous value of each output voltage of X1 to X6 is

It can be expressed as Here, t is time and T is a period.

The switching circuit 43 connects the output terminal Vj (j = 1, 2,..., 6) according to the signal Pm (m = 1, 2,..., 6) output from the switching pattern control circuit 44. Connect to input voltage X _Pm .
For example,
(P1, P2, P3, P4, P5, P6) = (1, 2, 4, 2, 1, 5)
When
(V1, V2, V3, V4, V5, V6) = (X1, X2, X4, X2, X1, X5)
It is connected so that it becomes.

  The clock generation circuit generates clock pulses CLK at a constant cycle. For example, a pulse is generated every period T.

  The switching pattern control circuit 44 refers to the switching pattern table every time the clock pulse CLK is input, and changes the output signal Pm (m = 1, 2,..., 6).

  In the switching pattern table, time change patterns of signals Pm (m = 1, 2,..., 6) output from the switching pattern control circuit are stored in advance.

  FIG. 6A shows an example of the contents of the switching pattern table. The switching pattern control circuit 44 outputs Pm corresponding to u = 1 in the initial state. Each time a clock pulse CLK is input, Pm corresponding to u = 2, 3,. In the case of FIG. 6A, the maximum value of u is 15, and when the clock pulse CLK is input in the state of u = 15, the state returns to u = 1.

  FIG. 6B is a waveform diagram of a six-phase AC voltage output from the AC power supply unit 40 controlled by the content of the switching pattern table shown in FIG. Here, the horizontal axis represents time, and the vertical axis represents voltage. Since the values of t / T and u are also shown, the waveforms of V1 to V6 are intermittent according to the switching of P1 to P6 with the passage of time, as can be seen from comparison with FIG. Switch to

  Next, the force acting on the particles placed in the electrostatic field gradient that gradually changes in space is obtained. For simplicity, it is assumed that the relative permittivity of the particles is about the same as 1, and the change in the electric field due to the presence of the particles is sufficiently small. At this time, the change amount U of the electrostatic energy of the entire space is

It is known that Where εo is the dielectric constant of vacuum, εr is the relative dielectric constant of the particle, E is the magnitude of the electric field, and the integration range is for the volume V of the particle.

  The force F that acts when this particle is placed in an electrostatic field with a sufficiently gentle spatial gradient with respect to the particle diameter is

It is represented by Here, the symbol ∇ represents a gradient.

  Focusing on the force x component Fx in equation (3),

Get.

  From formulas (3) and (4), it can be seen that a force is applied to the particles in the direction in which the electric field is large.

  Up to this point, an electrostatic field that does not change with time has been dealt with. However, the above discussion is almost true even when the electrostatic field changes with time. Now, focusing on the motion on the x-axis, if Equation (4) is written so that the dependence on the time t and the coordinate x is explicit:

Is obtained.

  Next, the force received by the particles moving along the array electrode substrate portion is specifically obtained. In the following discussion, attention is paid only to the force in the x direction represented by Expression (5). In addition, the force acting on the particles includes a z-direction force received from the electric field, a friction force received from the substrate surface, a Coulomb force based on charging, and a force due to the viscosity of the air. Even if it acts, it is considered that the effect of the present invention is not greatly affected.

  In the array electrode substrate portion having the structural parameters as shown in FIG. 4, a particle having a radius of 4 μm in contact with the upper surface of the array electrode substrate portion is considered (for convenience of explanation, the particle scale shown in FIG. Does not match the scale of the other parts). Here, the material of the particles is alumina, and the relative dielectric constant is 8.5. The dielectric constants of the dielectric substrate 51 and the cover coat 54 are both 5.24.

(A) In the case of the conventional method In order to help understanding of the special operation of the particle transport device according to the first embodiment of the present invention, first, the movement of particles by the conventional voltage application method will be described with reference to FIG. explain.
The conventional voltage application method corresponds to the case where the voltage output of the switching pattern u = 1 shown in FIG.

  FIG. 7 is a graph showing the change in the x component Fx (x) of the force received by the particles at t = 0 to T. FIG. 7 shows the passage of time from the top to the bottom. In each waveform, the point that crosses the axis of Fx (x) = 0 from positive to negative corresponds to a stable equilibrium position (stable point) because a restoring force acts on the position perturbation.

  First, consider a case where the particle is at a position A1 and is stationary at t = 0. A1 is one of the stable equilibrium positions.

  Next, consider the case where time has elapsed and t = T / 12. FIG. 7 shows that a small force in the + x direction works at A2.

  At this time, if the force to keep the particles at A2 is sufficiently small, the particles continue to move in the + x direction, for example, to another stable equilibrium position B2. Similarly, it is considered that the particles move in the order of C3 → D4 → E5 → F9 → G13 with the passage of time. Thus, during time T, the particles will travel a distance L / 2.

  On the other hand, when the force Fx (x) acting on the particle located at A2 is smaller than the force (such as frictional force received from the substrate surface) that holds the particle at A2, the particle is A3, A4, A5, A6, A1 ′. It is expected to remain in the position corresponding to. Thus, depending on conditions, some particles remain in place. That is, particles stay at this singular point.

(B) Case According to First Embodiment Next, the movement of particles when the voltage application method according to the first embodiment of the present invention is used will be described with reference to FIG.
FIG. 8 is a graph showing the change of the x component Fx (x) of the force received by the particles at t = 4T to 5T. This represents Fx (x) at u = 5 (t = 4T to 5T) among the repetitions of the switching pattern u = 1 to 15 shown in FIG. FIG. 8 shows the passage of time from the top to the bottom.

  First, consider a case where the particle is at the position of AA1 and is stationary at t = 4T. This position is the same position as A1 shown in FIG. The particle at the position AA1 receives a force in the + x direction at time t = 4T + T / 12. Since the magnitude of this force is greater than any time in the conventional method shown in FIG. 7, there is a high possibility that the force will move against the force that holds the particles on AA1.

  In this way, in addition to the switching pattern that gives the effect as shown in FIG. 7 to the particles, an irregularity such as u = 5, u = 10, u = 15 shown in FIG. By inserting a simple switching pattern, the stationary particle is moved and moved again. The switching of the electrode application pattern is performed by selecting one of the phases n (the number of phases that the drive voltage can take).

  Here, the force that the particles receive is reviewed from the viewpoint of the maximum value on the time axis. The particle motion is limited to one dimension along the direction of arrangement of the array electrodes. First, the maximum value on the time axis of the absolute value of the force received by the particle at the coordinate position x

It can be expressed as. Here, max {f | A} is a function that gives the maximum value of the function f under the condition A regarding the independent variable.
further,

It can be expressed as. Here, min {f | A} is a function that gives the minimum value of the function f under the condition A regarding the independent variable.
The larger the F ^min-max given in this way, the smaller the proportion of particles that remain.
In the case of the conventional method (a) and the first embodiment (b) of the present invention,

  Therefore, it is possible to reduce the proportion of particles that remain by the method of this embodiment including the switching pattern that gives the particles the effect as shown in (b).

<< Second Embodiment >>
In the first embodiment, the waveform of the AC voltage is a sine wave, but the second embodiment is an example in which this is a rectangular wave.

The block configuration of the AC power supply unit is the same as that shown in FIG.
FIG. 10A shows an example of the contents of the switching pattern table in FIG. The switching pattern control circuit 44 outputs Pm corresponding to u = 1 in the initial state. Each time a clock pulse CLK is input, Pm corresponding to u = 2, 3, and 4 is output. In the case of FIG. 10A, the maximum value of u is 4, and when the clock pulse CLK is input in the state of u = 4, the state returns to u = 1.

  FIG. 10B is a waveform diagram of a six-phase AC voltage that is controlled by the contents of the switching pattern table shown in FIG. Here, the horizontal axis represents time, and the vertical axis represents voltage. The values of t / T and u are also shown. As is clear from comparison with FIG. 10A, the waveforms of V1 to V6 are intermittently switched according to the switching of P1 to P6 over time.

  As described above, even when the waveform of the AC voltage is a rectangular wave, a stable point is hardly generated as in the case of the first embodiment, and the retention of particles can be eliminated.

  In the second embodiment, since the average positive / negative time of the AC voltage waveform is unbalanced, a DC bias is applied. However, the waveform may have a uniform average time between the positive period and the negative period. .

In addition, a sine wave on which a triangular wave or a harmonic component is superimposed may be used, and generally the same effect can be obtained by applying to an alternating voltage.
Moreover, in the example shown above, although the number of phases was set to 6 of V1-V6, the number of phases n is not restricted to 6.

It is a perspective view of the particle transportation device shown in patent documents 1. It is a side view of the particle transport apparatus shown by patent document 1. It is a figure which shows the structure which applies a voltage with respect to the some linear electrode of the particle transport apparatus which concerns on 1st Embodiment, (A) is a top view of the dielectric substrate in which the linear electrode was formed, ( B) is a side view thereof. FIG. 4 is a cross-sectional view of the particle transport device according to the first embodiment, and is a diagram illustrating an example of specific dimensions in order to specifically determine the force that particles moving along the arrayed electrode substrate portion 50 receive. (A) is a block diagram of the whole particle transport apparatus, (B) is a block diagram which shows the structure of an alternating current power supply part. (A) is an example of the content of the said switching pattern table, (B) is a wave form diagram of the 6-phase alternating voltage output from the alternating current power supply part 40 controlled by the content of the switching pattern table shown to (A). The x component of the force that the particle receives from t = 0 to t = T is the particle motion by the conventional voltage application method corresponding to the case where the voltage output of the switching pattern u = 1 shown in FIG. It is the figure which drew Fx (x). FIG. 7 is a diagram depicting an x component Fx (x) of a force that a particle receives from t = 4T to t = 5T, with respect to the movement of the particle according to the first embodiment controlled by the switching pattern shown in FIG. . It is a figure which shows the maximum value of the absolute value of the force which a particle | grain receives about the case of the conventional method (a) and 1st Embodiment (b). (A) is an example of the content of the switching pattern table in the particle transport apparatus according to the second embodiment, and (B) is controlled by the content of the switching pattern table shown in (A) and output from the AC power supply unit 40. It is a wave form diagram of 6 phase alternating voltage.

Explanation of symbols

DESCRIPTION OF SYMBOLS 40 ... AC power supply part 41 ... Clock generation circuit 42 ... Six-phase AC voltage source 43 ... Switching circuit 50 ... Array electrode substrate part 51 ... Dielectric substrate 52 ... Linear electrode 53 ... Connection part 54 ... Cover coat

Claims (2)

Linear electrodes arranged parallel or substantially parallel to each other;
The arrangement order number of the linear electrodes is represented by k (k is an integer starting from 0), the number of phases that can be taken by the periodically changing driving voltage to be applied to the linear electrodes is represented by n , and the remainder function is represented by In terms of Mod,
p = Mod (k, n) +1
A voltage applying means for applying a p-phase driving voltage represented by the following to the linear electrodes of the array sequence number k:
The driving voltage is an alternating voltage of the n-phase, the voltage applying means, by selecting one of the phases of the alternating voltage of the n-phase with time, the pattern of the voltage applied to the linear electrodes particle transport device in which you switch discontinuously over time to. 2. The particle transport device according to claim 1 , wherein the plurality of linear electrodes are arranged on a dielectric or insulating substrate, and an insulating film is coated on the linear electrodes.

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