JPH07121380B2 - Liquid discharge device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a high-precision liquid ejection device used in the production of semiconductors, pharmaceuticals, foodstuffs and the like.

(Prior Art) Generally, in a process in which the amount of discharged liquid is required to be accurate, such as a semiconductor manufacturing process, a liquid discharging device as shown in FIGS. 2 to 5 is used.

In FIG. 2, the solenoid valve 1 is operated to bring the pump 3 into the suction state via the speed controller 2.

At this time, since the close valve 4 is closed, the pump 3
Sucks the processing liquid 7 contained in the container 6 through the check valve 5.

Next, when the operation of the solenoid valve 1 is stopped, the pump 3 enters the discharge state via the speed controller 8 and the nozzles via the close valve 4 and suck back valve 9.
10 The processing liquid 7 is discharged from the tip. When the discharge is completed, the solenoid valve 1 is operated to bring the pump 3 into the suction state, and the suck bag valve 9 causes the nozzle 10
The processing liquid 7 therein is pulled back toward the suckback valve 9.

On the other hand, in FIG. 4, the treatment liquid 47 contained in the container 46 is sucked by the pump 43 via the check valve 45. next,
When the pump 43 is put into the discharge state, the processing liquid 47 sucked into the pump 43 is discharged from the tip of the nozzle 50 via the check valve 44 and the suck back valve 49. Then, when the ejection is completed, the processing liquid 47 in the nozzle 50 is pulled back as described above.

(Problems to be Solved by the Invention) However, the above-described device has the following problems.

First, in the apparatus shown in FIG. 2, when the closing valve 4 is closed, it is impossible to prevent the pumping action of the processing liquid 7 in the closing valve 4 toward the outside, and the discharge amount is stable. do not do.

FIG. 3 shows the internal structure of the closed valve 4.
The cylinder 12 presses the valve 12 against the valve seat 13 to make it liquid-tight.
Generally, the valve 12 is fixed to the diaphragm 14 or the like,
When the valve 12 descends and closes, the diaphragm 14 deforms toward the valve seat 13 side. Therefore, the volume of the liquid chamber 15 is reduced, and the processing liquid is discharged outside the close valve 4.

In order to reduce the influence of this discharge, the operation timing of the pump 3 and the close valve 4 is adjusted in order to absorb the pumping action of the close valve 4 by the suction force of the pump 3. However, in general, pump 3, close valve 4
Since both are driven by air pressure, it is extremely difficult to always stabilize the timing of both.

For example, if the closing speed of the close valve 4 is faster than the suction speed of the pump 3, the processing liquid 7 is extruded to the nozzle 10 side.

Conversely, if it is late, a large amount of the processing liquid 7 will be absorbed by the pump 3 from the nozzle 10 side.

Next, in the apparatus shown in FIG. 4, stability and reliability of the check valves 44 and 45 are problems, and the processing liquid 47 is likely to drip from the nozzle 50 and backflow to the container 46.

The check valves 44 and 45 serve as a check mechanism when pressure is applied to the valves, but when the pressure is not applied, for example, when the pump 43 is stopped, a liquid leakage backflow may occur.

That is, as shown in FIG. 5, the check valves 44 and 45 are the balls 51.
Comes into contact with the seat 52 and becomes liquid-tight, but when pressure is not applied, the ball 51 becomes liquid-tight only by its own weight.

Therefore, even if the balls 51 and the seats 52 are extremely minute, if there are scratches, surface roughness, etc., liquid leakage will occur. For example, if the nozzle 50 is located higher than the container 46, the treatment liquid 47 will flow back toward the container 46 if left for a long time, and the nozzle 50 will
If the position is lower than 46, the processing liquid 47 will leak from the tip of the nozzle 50.

Here, the check valves 44 and 45 are more reliable, for example, the check valve 4 forcibly pressing the ball 51 with a spring or the like.
It is also possible to use the one in which the number of check valves 44 and 45 used is increased, as well as the number of check valves 44 and 45. However, in this case, a strong force is required to open the check valves 44 and 45, and the flow path resistance increases, so that the high viscosity liquid cannot be handled.

In addition, when the check valves 44 and 45 are used in series, or when a pressure member such as a spring is placed in the check valves 44 and 45, bubbles and the like are likely to accumulate inside, and the discharge amount becomes unstable. .

The present invention has been made in consideration of the above-mentioned conventional circumstances, and an object of the present invention is to provide a liquid ejection device that is easy to adjust and has high ejection accuracy.

[Structure of Invention]

(Means for Solving Problems) That is, according to the present invention, a pump that sucks and discharges a liquid to be discharged, a first valve that intermittently controls the flow of the liquid to be discharged, and the liquid to be discharged passes only in one direction. A check valve, a second valve that pulls back the liquid to be discharged in a direction opposite to the discharge direction at the end of discharge, and the pump and the first valve are provided toward the flow path of the discharge liquid.
The valve, the check valve, and the second valve are provided in this order.

(Operation) In the liquid discharge device of the present invention, the pump, the first valve, the check valve, and the second valve are arranged and connected in this order in the liquid discharge direction. The liquid on the valve side of No. 2 does not flow backward, and it is possible to prevent the liquid from flowing inside the device when the pump is stopped.

(Example) Hereinafter, one example of the liquid ejection apparatus of the present invention will be described with reference to the drawings.

A pump 102, a first valve such as a close valve 103, a check valve 104, a second valve such as a suck back valve 105, and a nozzle 101 are arranged and connected in series in this order toward a liquid discharge nozzle 101.

The suction port 106 of the pump 102 is pipe-connected to the check valve 107, and the processing liquid 109 contained in the container 108 can be sucked through the check valve 107.

Further, the pump 102 performs a suction / discharge operation by a speed controller 111 for adjusting the suction speed of the pump 102 connected to the solenoid valve 110 and a speed controller 112 for adjusting the discharge speed.

Next, a speed controller 113 for adjusting the closing operation speed is connected to the close valve 103, and a speed controller 114 for adjusting the suction speed is connected to the suck back valve 105 for returning the treatment liquid 109 in the nozzle 101 after the end of discharge. There is.

Both speed controllers 113 and 114 are pumps.
It is connected to the same solenoid valve 110 output as the speed controller 111 of 102.

Next, the operation will be described.

First, a solenoid valve connected to an air pressure source (not shown)
When 110 is operated and the operation of the pump 102 is set to the discharge state, the processing liquid 109 sucked by the pump 102 is pushed out and discharged from the tip of the nozzle 101 through the close valve 103, the check valve 104, and the suck back valve 105. .

After the end of discharge, when the operation of the solenoid valve 110 is stopped, the pump 102 is in a suction state, the close valve 103 is closed, and the suck back valve 105 sucks the processing liquid in the nozzle 101 and pulls it back.

At this time, the speed controllers 111 and 113 are adjusted so that the close valve 103 is closed first within the time from the start of the suction of the processing liquid 109 by the pump 102 via the check valve 107 to the end thereof. .

Then, since the pump 102 is in the suction state, the check valve 104
Acts, there is no backflow of the liquid from the suck back valve 105 side, and the extruded liquid due to the pumping action when the close valve 103 is closed is completely absorbed by the pump 102, so that the treatment liquid 109 is not pushed out from the nozzle 101. Absent.

Further, even if the apparatus is left in a state where the pump 102 is in a resting state, the check valve 104, 107 and the closing valve 103 are provided, so that the flow path is completely closed. It does not flow back or leak from the nozzle 101.

In addition, as an adjusting method of the present apparatus, for example, the following adjustment is performed.

First, the speed controller 112 of the pump 102 adjusts to an appropriate discharge speed. Next, the speed controller 113 of the close valve 103 is gradually loosened from the squeezed state, and the close valve 103 is adjusted so as to be closed between the start of suction of the pump 102 and the end of suction. This adjustment is
Since the suction time of the pump 102 is long, it can be easily performed.

After that, adjust the suction amount of the suck back bule 105 with the adjusting screw 115.
Then, the suction speed is adjusted by the speed controller 114.

If the check valve 104 and the suck back valve 105 are arranged in reverse, the suck back operation for returning the treatment liquid 109 in the nozzle 101 at the end of liquid discharge cannot be performed. Therefore, the check valve 104 is arranged between the close valve 103 and the suck back valve 105 as in the present embodiment.

〔The invention's effect〕

As described above, according to the present invention, since the liquid to be ejected does not flow back or leak out, the ejection accuracy is high, the adjustment is easy, and stable liquid ejection can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the liquid discharge device of the present invention,
2 and 3 are block diagrams showing one conventional example, and FIG. 4 and FIG. 5 are block diagrams showing another conventional example. 102 ... Pump, 103 ... Close valve, 104 ... Check valve, 105 ... Suckback valve, 107 ... Check valve, 11
1,113 …… Speed controller.

Claims (1)

[Claims] 1. A pump for sucking and discharging the liquid to be discharged, a first valve for intermittently controlling the flow of the liquid to be discharged, a check valve for passing the liquid to be discharged only in one direction, and discharging the liquid to be discharged. A second valve that pulls back in the direction opposite to the discharge direction at the end is provided, and the pump, the first valve, the check valve, and the second valve are provided in this order toward the flow path of the discharge liquid. Characteristic liquid ejection device.