JPH03134275A - Micro-dispensing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a portable device that discharges a small amount of fluid continuously or intermittently for a predetermined period of time.

[Prior Art] Conventionally, as shown in FIG. 7, a small amount dispensing device uses an electromagnetic actuator 701 as a driving force, and a transmission device 702 which is a combination of large and small gears is coupled to this, thereby moving a syringe barrel into an arm. 704 is proposed in Japanese Patent Application Laid-open No. 54-12191 and Japanese Patent Publication No. 61-22599.

[Problems to be Solved by the Invention] However, since this uses an electromagnetic actuator, it is vulnerable to electromagnetic noise and consumes a large amount of current. Also, since gears are used, backlash may occur,
The discharging unit has large variations and the structure is complicated. Furthermore, since the syringe barrel is pushed, the overall shape becomes large, which poses a problem for portable use. SUMMARY OF THE INVENTION An object of the present invention is to provide a small portable micro-volume ejection device that is resistant to electromagnetic noise, consumes less current so that a small battery can be used for portable use, and has good ejection accuracy.

[Means for Solving the Problems] A micro-discharge device of the present invention includes at least a pump unit having a ceramic or organic piezoelectric element, an integrated circuit for operating the pump unit, and a power source for operating the integrated circuit. It is characterized by consisting of.

[Function] According to the above configuration of the present invention, a drive pulse voltage is applied to the piezoelectric element in response to a drive signal from the integrated circuit, and the piezoelectric element expands and contracts in the radial direction.

Therefore, the diaphragm to which the piezoelectric element is attached vibrates up and down, and this movement causes the fluid in the tank to be sucked into the pump unit and discharged from the discharge port.

[Embodiment] Next, details of the present invention will be explained with reference to the drawings. FIG. 1 shows an embodiment of a micro-discharge device according to the present invention.

The micro-discharge device according to the present invention includes a pump unit 101 consisting of a piezoelectric element, a diaphragm, a check valve, and a main body having an inlet, an outlet, and a flow path, an integrated circuit 102 for operating the pump unit 101, and an integrated circuit 102 for operating the pump unit 101. A circuit 102, a circuit block 103 consisting of electrical elements such as a boost coil and a capacitor, a board, etc., a battery 104 as a power source,
External operation switch 105, tank 106, case 107
and a display body 108.

FIG. 2 is a detailed view of the pump unit 101.

Piezoelectric element 201, electrode metal plate 202, diaphragm 203,
Suction check valve 204, discharge check valve 205, and suction port 2
06, discharge port 207, suction valve chamber 208, discharge valve chamber 209
The main body 210 includes a main body 210 having a pressurizing chamber 211, a suction hole 212 between the pressurizing chamber and the valve chamber, and a main body B 214 having a discharge hole 213. B main body 214 is check valve 204
．． A main body 210 incorporating 205 and piezoelectric element 2
01. The diaphragm 203 to which the electrode metal plate 202 is attached is assembled by ultrasonic welding or adhesive.

FIG. 3 is an embodiment of a circuit block diagram of the present invention. 3
01 is a power source such as a lithium battery, 302 is a booster circuit, 30
3 is a CPU, and 304 is a level shifter that converts a low voltage signal into a high voltage signal. 305 is a driver that drives the piezoelectric element 306. 307 is a display device 308 that displays the flow rate of the pump, and a switch that selects the flow rate and the like. The flow rate is selected by the switch 308, and the CPU 3
A pump drive signal is output from 03. CPU signals are generally operated at a voltage of 3 to 5 volts, and piezoelectric elements are operated at a high voltage such as 50 volts. Therefore,
A booster circuit 302 boosts the voltage from 3 volts to 50 volts, and a level shifter 304 converts the signal from the CPU to 50 volts.
Convert to 0 volt signal.

FIG. 4(a) shows an embodiment of a directional chopper type booster circuit. 401.402 are input terminals, and 403.404 are output terminals. Terminals 401 and 403 are common electrode Vdd
It becomes. 402 is a low voltage Vssl such as 13 volts
, 404 is a high voltage Vssh such as 150 volts. 4
05 is a boost coil, 406 is a first switching element,
407 is a control circuit that controls on/off of the first switching element 406; 408 is a feedback circuit made up of resistors 409 and 410; 411 is a smoothing capacitor for smoothing the output, 415 is a reverse current prevention diode, 412 is a DC input, 413 is a DC output, and 414 is a control signal for controlling the switching element 406. When the switching element 406 is turned on by the control signal 414, the direct current human power 41
The current supplied from No. 2 begins to flow through the boost coil 405 and the switching element 406, increases with time, and energy proportional to the square of the flowing current value is stored in the boost coil 405. Next, the switching element 40
6 is turned off, the energy stored in the boost coil 405 is stored in the smoothing capacitor 411 through the backflow prevention diode 415. Here, the backflow prevention diode 415 prevents the charge accumulated in the smoothing capacitor 411 from escaping through the switching element 406 when the switching element 406 is turned on.

The DC output 413 is voltage-divided by a feedback circuit 408 composed of resistors 409 and 410 and sent to the control circuit 407, and its value is compared with a reference voltage inside the control circuit 407.

A control circuit 407 switches a control signal 414 based on the comparison result to control ON/OFF of the switching element 406 so that the DC output 413 becomes a constant value.

FIG. 4(b) is an example of a level shifter circuit.

421 is a signal input Vin, into which signals of Vdd and Vssl levels are input, and 422 is a signal output VO, which is input with Vdd and Vssl level signals.
d, a Vssh level signal is output. 423 is an inverter 424) tVdd, 425 is Vssh, 42
6.427 is a P-channel FET, and 428.429 is an N-channel FET. When a Vdd level signal is input to 421, transistors 427 and 428 are turned on and transistors 426 and 429 are turned off. Therefore, Vdd is output to the output 422. Also Vin42
When a Vssl level signal is applied to 1, transistors 426 and 429 turn on, and transistor 427
．． 428 is turned off, and a Vssh level signal is output to the output 422.

Figure 4C) is an example of a driver circuit. 440 is an input signal Vin, 441 is an inverter, 442.443 is a level shifter, 444.446 is a P-channel transistor, 445.447 is an N-channel transistor, 449 is a piezoelectric element, and 450.451 is an electrode of the piezoelectric element 449 It is. When a Vdd level signal is applied to the electrode 440, the transistors 444 and 447 are turned off and the transistors 445 and 446 are turned on, so that the voltage of Vssh and the voltage of Vdd are applied to the electrode 450 and the electrode 451t, respectively. Further, when a signal of Vssl is applied to the electrode 440, a voltage of Vdd is similarly applied to the electrode 450, and a voltage of Vssh is applied to the electrode 451, thereby driving the piezoelectric element.

FIG. 5 shows the operation of the pump unit.

FIG. 5(a) shows the pump unit. 501 is a piezoelectric element, 502 is a metal plate for an electrode, a diaphragm 516, a suction check valve 503, a discharge check valve 504, and an A having a suction port 505, a discharge port 506, a suction valve chamber 507, and a discharge valve chamber 508. A main body 513 having a main body 509, a pressurizing chamber 510, a suction hole 511 between the pressurizing chamber and the valve chamber, and a discharge hole 512.
The pressure chamber 510 and valve chambers 507 and 508 are filled with liquid. The electrode on the top surface of the piezoelectric element 501 is 514, the electrode on the bottom surface is 515, and Vdd is applied to the electrode 514.
, 515 contract in the radial direction when a voltage of Vssh is applied to them. Also, Fig. 4(c)
corresponds to terminal 451.450 of . FIG. 6 shows the drive waveform of the pump unit in FIG. 5. FIG. 6(a) is the drive waveform output from the CPU 303 in FIG.
Figures (b) and (C) are terminals 514 and 51 of Figure 5, respectively.
Corresponds to 5. In the period 601 in FIG. 6, Vd is 514.
d, 515 is applied with a voltage of Vssh, and the piezoelectric element 50
1 contracts in the radial direction, the diaphragm 516
It is displaced convexly downward as shown in Figure (b).

Then, the liquid filled in the pressurizing chamber 510 is pressurized and pushes down the discharge check valve 504, moving the liquid to the discharge port 506. Also, since the suction check valve 503 is present, the liquid filled in the pressurizing chamber 51
There is no backflow of liquid from 0 to inlet 505. Next, the sixth
During the period 602 in the figure, Vssh is applied to the electrode 514, and the electrode 51
5 is applied, and the piezoelectric element 501 expands in the radial direction, so that the diaphragm 516 is displaced in an upwardly convex manner as shown in FIG. 5(C). Then, the liquid filled in the pressurized chamber 510 is depressurized, pushes up the suction check valve 503, and flows from the suction port 505 into the pressurized chamber 51.
Move the liquid to 0. Further, since the discharge check valve 504 is provided, there is no movement of liquid from the pressurizing chamber 510 to the discharge port 506. By repeating the operations shown in FIGS. 5(b) and 5(c) above, it becomes possible to move the liquid from the suction port 505 to the discharge port 506.

[Effects of the invention] As explained above, since a pump using a piezoelectric element is used as a micro-volume dispensing device, the number of components can be reduced compared to a dispensing device using an electromagnetic actuator, making it possible to reduce the size and cost. can be reduced, and the shape of the tank is not limited, so there is more freedom in the shape of the discharge device.

In addition, since the piezoelectric element is a voltage-driven actuator, the current consumption is on the order of μA, so the current consumption can be reduced, and even with a power source such as a lithium battery, a portable micro-dispensing device can be used over the life of the battery. Furthermore, in a micro-dispensing device using an electromagnetic actuator, the flow rate cannot be adjusted for each step, but since this micro-dispensing device uses a piezoelectric element, the amount of displacement, that is, the dispensing amount, can be controlled by voltage. In addition to frequency control, the flow rate can be controlled by voltage for each step, making it possible to finely adjust the discharge amount. The piezoelectric element has a displacement of 1 μm.
It is also possible to control the amount below, and unlike a dispensing device using an electromagnetic actuator, there is no backlash caused by gears, so if a pressurized chamber with a diameter of 10 mm is used, the volume is very small at 0.02 μl in terms of volume. Accurate control over large quantities is possible. Furthermore, since piezoelectric elements are not affected by magnetic fields, they do not malfunction like electromagnetic actuators even in the presence of a magnetic field, making it possible to provide a highly safe micro-discharge device.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are diagrams showing an embodiment of a minute amount discharging device of the present invention. FIG. 2 is a diagram showing the pump unit. FIG. 3 is a circuit block diagram of the micro-discharge device of the present invention. FIG. 4(a) is a booster circuit diagram, FIG. 4(b) is a level shifter diagram, and FIG. 4(C) is a diagram showing an example of a driver. FIGS. 5(a) to 5(C) are explanatory views of the operation of the pump unit. FIG. 6 is a drive signal diagram of the pump unit. FIG. 7 is a diagram showing a conventional example. Seiko Epson Corporation

Claims (1)

[Claims] A micro-volume dispensing device comprising at least a pump unit having a ceramic or organic piezoelectric element, an integrated circuit for operating the pump unit, and a power source for operating the integrated circuit.