JP3884443B2 - Liquid dispensing apparatus, liquid dispensing method, and liquid discharge head - Google Patents

Description

The present invention relates to a liquid dispensing apparatus , a liquid dispensing method, and a liquid discharge head .

2. Description of the Related Art Conventionally, a liquid dispensing apparatus using an ejection head that ejects a minute amount of liquid with high accuracy using an inertia force generated using an acceleration application element such as a piezoelectric element is known.
As such a liquid dispensing device, a liquid discharge head and a syringe piston pump for sucking liquid into the liquid discharge head are provided. When dispensing liquid, first, a syringe for suction There is known a technique in which a liquid is sucked into a flow path member inside a liquid discharge head by a piston pump, and then a driving means including a piezoelectric element is driven to discharge the liquid (for example, see Patent Document 1).
According to this liquid ejection head, when a pulse voltage is applied to the driving means, the flow path member that holds the liquid reciprocates in the axial direction by driving the piezoelectric element, so that an inertial force acts on the liquid in the flow path member. Thus, a predetermined amount of liquid can be discharged.
JP 2001-235400 A

However, in the conventional liquid discharge head, the liquid suction amount may vary due to reasons such as variations in suction force of the syringe piston pump. That is, in the conventional liquid discharge head using inertial force, when the suction amount changes, the inertial force acting on the liquid also changes. As a result, there is a problem that the discharge amount of the discharged fluid also changes.
The present invention has been made in view of the above circumstances, and provides a liquid dispensing apparatus, a liquid dispensing method, and a liquid ejection head capable of precisely controlling a liquid ejection amount by controlling a driving voltage waveform of a driving unit. The purpose is to do.

The present invention employs the following means in order to solve the above problems.
The liquid dispensing apparatus according to the present invention includes a liquid holding member having a flow path inside and holding the liquid in the flow path, and having a discharge port for discharging the liquid at one end, and a supplied pulse voltage. Te, drive means for advancing and retracting the liquid holding member along the discharge direction of the liquid, the residual vibration generated by the action of the inertial force due to forward and backward movement of the liquid holding member in the liquid in the liquid holding member The drive so that the period of natural vibration of the liquid held in the liquid holding member and the period of forward / backward movement of the liquid holding member are substantially the same so as to cancel after the supply of the pulse voltage is stopped. And means for supplying and stopping the supply of the pulse voltage.

Further, the liquid dispensing apparatus according to the present invention is the liquid dispensing apparatus, wherein the pulse voltage supply unit is configured such that the vibration of the liquid holding member after the supply of the pulse voltage is stopped with respect to the residual vibration. The supply of the pulse voltage is stopped so as to shift the period.

The liquid dispensing apparatus according to the present invention is the liquid dispensing apparatus, wherein the width of the pulse voltage is substantially the same as one cycle of the natural vibration of the liquid held in the liquid holding member. It is characterized by that.

The liquid dispensing method according to the present invention includes a liquid holding member having a flow path inside and holding the liquid in the flow path, and having a discharge port for discharging the liquid at one end, and a supplied pulse voltage. The liquid in the liquid dispensing apparatus includes: a driving unit that moves the liquid holding member forward and backward along the liquid discharge direction; and a pulse voltage supply unit that supplies and stops the supply of the pulse voltage to the driving unit. a dispensing method comprising: supplying a pulse voltage to said driving means, said residual vibration is the pulse voltage generated in the liquid in the liquid holding member by the action of the inertial force due to reciprocating movement of the liquid holding member as canceled after stopping the supply, the period of natural vibration of the liquid held in the liquid holding member, so that the period of forward and backward movement of the liquid holding member is substantially the same, the Characterized by comprising the step of stopping the supply of the pulse voltage to the moving means.

The liquid discharge head according to the present invention includes a liquid holding member having a flow path inside and holding the liquid in the flow path, and having a discharge port for discharging the liquid at one end, and a supplied pulse voltage. a driving means for advancing and retracting the liquid holding member along the discharge direction of the liquid, the residual vibration generated by the action of the inertial force due to forward and backward movement of the liquid holding member in the liquid in the liquid holding member The period of the natural vibration of the liquid held in the liquid holding member and the period of forward / backward movement of the liquid holding member are substantially the same so as to cancel after the supply of the pulse voltage is stopped. Drive means for supplying and stopping supply of a pulse voltage.

  According to the present invention, it is possible to improve the accuracy of the liquid discharge amount from the liquid holding member.

A first embodiment according to the present invention will be described with reference to FIG.
A liquid dispensing apparatus 1 according to the present embodiment is an apparatus for discharging and dispensing a liquid such as a biological sample, a reagent, or a molten metal with a very small amount with high accuracy, and a liquid discharge head 2 that discharges liquid. The liquid discharge head 2 includes a syringe pump 3 that sucks liquid.
The liquid discharge head 2 includes a liquid passage 6 disposed in a liquid holding member 5 formed in a cylindrical shape, and a driving means for moving the liquid passage 6 around the liquid passage 6 along the longitudinal direction of the liquid passage 6. The piezoelectric element 7 provided is provided.
The liquid passage 6 has a cylindrical flow path 6A inside, and a bottom 6B is provided on the lower end surface so as to hold the liquid F in the flow path 6A. In addition, a discharge port 8 is formed in the bottom portion 6B so that the liquid F can be discharged from one end of the flow path 6A.

The liquid passage 6 includes a screw member 10 fixed to the outer peripheral surface. By screwing the screw member 10 with a lower end flange portion 7A of the piezoelectric element 7, the piezoelectric element 7 has a natural vibration mode and is liquid. The direction of stretching vibration in the longitudinal direction of the passage 6 and the direction of liquid discharge from the liquid holding member 5 are substantially the same direction, and the liquid discharge head 2 in which the liquid passage 6 and the piezoelectric element 7 are integrated is obtained.
In the piezoelectric element 7, the two divided electrodes 7 a and 7 b are electrically connected to the pulse voltage supply unit 11, and the vibration frequency F1 when the liquid holding member 5 moves forward and backward is the natural frequency of the liquid F. It can be set substantially the same as F2.

Next, the operation of the liquid discharge head 2 and the liquid dispensing apparatus 1 according to this embodiment and the liquid dispensing method will be described.
First, in a state where the vibration frequency F1 when the liquid holding member 5 is moved back and forth and the natural frequency F2 of the liquid F are set to the same value as, for example, 10 kHz, the liquid F is discharged from the liquid discharge head 2 by the syringe pump 3. Into the liquid passage 6. When a pulse voltage is applied from the pulse voltage supply unit 11 to the piezoelectric element 7, the piezoelectric element 7 expands and contracts in the longitudinal direction of the liquid passage 6, and accordingly, the liquid passage 6 reciprocates in the longitudinal direction via the screw member 10. To do.

At this time, since the liquid F cannot follow the rapid movement of the liquid holding member 5, an inertial force opposite to the moving direction of the liquid holding member 5 acts on the liquid F to generate a discharge pressure on the liquid F and the liquid F F reciprocates in the liquid passage 6. At this time, since the vibration frequency F1 of the liquid holding member 5 is the same as the natural frequency F2 of the liquid F, the frequency of vibration generated in the liquid F is limited to the natural frequency F2. Therefore, the liquid F reciprocates at the natural frequency F2, and the liquid F having a flow rate corresponding to the discharge pressure at this time is discharged from the discharge port 8.
Note that the discharge pressure varies according to the amount of the liquid F held in the liquid passage 6.

According to the liquid dispensing device 1, the liquid discharge head 2, and the liquid dispensing method, the vibration generated in the liquid F in the liquid holding member 5 can be limited to one frequency that is substantially the same as the vibration of the forward / backward movement. The discharge timing and discharge amount of the liquid F can be controlled by the vibration frequency, and a desired amount of the liquid F can be discharged from the discharge port 8 when necessary.

Next, a second embodiment will be described with reference to FIG.
In addition, the same code | symbol is attached | subjected to the component similar to 1st Embodiment mentioned above, and description is abbreviate | omitted.
The difference between the second embodiment and the first embodiment is that, in the liquid dispensing apparatus 1 according to the present embodiment, the liquid holding member 5 is moved back and forth by one cycle of vibration of the natural vibration mode. is there.
At this time, the piezoelectric element 7 from the pulse voltage supply unit 11, the action of inertial force to the liquid F by applying a rectangular wave E of substantially the same pulse width and unique vibration period T1.
Note that the configuration of the liquid ejection head 2 is the same as that of the first embodiment.

A case where the liquid F is ejected by the liquid ejection head 2 according to the liquid dispensing apparatus 1 will be described.
A pulse voltage is applied to the piezoelectric element 7 as a rectangular wave voltage, and the liquid holding member is vibrated to discharge the liquid F from the discharge port 8 as in the first embodiment.
Here, when the liquid holding member 5 is moved back and forth in the natural vibration mode of the piezoelectric element 7, even if the movement of the liquid holding member 5 is stopped, normal residual vibration is generated in the internal liquid F by the action of inertial force. Therefore, even if the liquid holding member 5 is stopped, the liquid F moves forward and backward, so the liquid F may be ejected in the second and third periods of the generated natural vibration.

However, in the present embodiment, by stopping supply after one cycle of the displacement of the liquid holding member 5 a voltage of rectangular wave E, the vibration cycle T2 of the liquid holding member 5, does not stop the supply of the voltage of the rectangular wave E It can be shifted by a half wavelength with respect to the vibration period T3 of the fluid F in this case.
Therefore, the vibration of the liquid F can be canceled by the vibration of the liquid holding member 5, and a liquid holding member 5 by forward and backward movement discharging the liquid F by the vibration of the secondary and subsequent cycles of the natural vibration modes of the liquid holding member 5 Can be suppressed.

Next, a third embodiment will be described with reference to FIGS.
In addition, the same code | symbol is attached | subjected to the component similar to other embodiment mentioned above, and description is abbreviate | omitted.
The difference between the third embodiment and the second embodiment is that, in the liquid dispensing apparatus 1 according to this embodiment, a reverse voltage is once applied to the piezoelectric element 7 with respect to the voltage at which the discharge pressure is generated. This is a point where a voltage generating a discharge pressure is applied.

For the case where the ejected liquid dispensing device thus liquid F in the liquid discharge head 2 according to 1 will be described.
First, as shown in FIG. 3, with respect to the initial state shown in FIG. 4A, a reverse voltage V1 in a direction opposite to the voltage at which the discharge pressure is generated is once applied after time t1. At this time, since the piezoelectric element 7 moves in the opposite direction to the case of the above embodiment, the inertia force of the liquid F acts in a direction in which the liquid F is not discharged, and as shown in FIG. The meniscus 15 generated in 8 is drawn into the flow path 6A.

Subsequently, a rectangular voltage in the same direction as in the second embodiment is supplied after time t2. If the voltage at this time is V2, even if the voltage is smaller than the voltage required in the second embodiment, the potential difference from V1 to V2 is made equal to the voltage required in the second embodiment. The inertial force similar to the above can be applied to the liquid F, and the liquid F can be discharged.
Therefore, the satellite generated behind the main droplet can be reduced, and the discharge accuracy of the liquid F can be improved.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, the fluid flow path 6A has a circular cross section, but a polygon such as a triangle or a square may be employed, and is not limited to a circle.

It is sectional drawing which shows the liquid discharge head of the liquid dispensing apparatus which concerns on the 1st Embodiment of this invention. 6 is a graph showing a relationship between a voltage applied to a liquid ejection head according to a second embodiment of the present invention and movement vibration. 10 is a graph showing a voltage applied to a liquid ejection head according to a third embodiment of the present invention. It is explanatory drawing which shows the movement state of the liquid discharge head which concerns on the 3rd Embodiment of this invention, and a liquid.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid dispensing apparatus 2 Liquid discharge head 5 Liquid holding member 6A Flow path 7 Piezoelectric element (drive means)
8 Discharge port 11 Pulse voltage supply unit

Claims (5)

A liquid holding member having a flow path inside and holding the liquid in the flow path, and having a discharge port for discharging the liquid at one end;
Drive means for moving the liquid holding member forward and backward along the liquid discharge direction in accordance with the supplied pulse voltage;
Wherein as the residual vibration generated in the liquid in the liquid holding member by the action of the inertial force due to reciprocating movement of the liquid holding member is canceled after the supply stop of the pulse voltage, which is held in the liquid holding the member A pulse voltage supply unit for supplying and stopping the supply of the pulse voltage to the drive means, so that the period of natural vibration of the liquid and the period of forward and backward movement of the liquid holding member are substantially the same ;
A liquid dispensing apparatus comprising:   The pulse voltage supply unit stops the supply of the pulse voltage so that the vibration of the liquid holding member after the supply of the pulse voltage stops is shifted by a half cycle with respect to the residual vibration. A liquid dispensing apparatus according to claim 1.   2. The liquid dispensing apparatus according to claim 1, wherein the width of the pulse voltage is substantially the same as one cycle of the natural vibration of the liquid held in the liquid holding member. A liquid holding member having a flow path inside and holding a liquid in the flow path, and having a discharge port for discharging the liquid at one end, along the discharge direction of the liquid according to the supplied pulse voltage A liquid dispensing method in a liquid dispensing apparatus, comprising: a driving unit that moves the liquid holding member forward and backward; and a pulse voltage supply unit that supplies and stops the supply of the pulse voltage to the driving unit,
Supplying a pulse voltage to the driving means;
Wherein as the residual vibration generated in the liquid in the liquid holding member by the action of the inertial force due to reciprocating movement of the liquid holding member is canceled after the supply stop of the pulse voltage, which is held in the liquid holding the member Stopping the supply of the pulse voltage to the driving means so that the period of natural vibration of the liquid and the period of forward and backward movement of the liquid holding member are substantially the same ;
A liquid dispensing method comprising: A liquid holding member having a flow path inside and holding the liquid in the flow path, and having a discharge port for discharging the liquid at one end;
A driving means for advancing and retracting the liquid holding member along the discharge direction of the liquid according to the pulse voltage supplied, the liquid holding member in the action of the inertial force due to forward and backward movement of the liquid holding member A period of natural vibration of the liquid held in the liquid holding member and a period of forward / backward movement of the liquid holding member so that the residual vibration generated in the liquid is canceled after the supply of the pulse voltage is stopped Driving means for supplying and stopping supply of the pulse voltage so that the two are substantially the same ,
A liquid discharge head comprising:

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