JP3492515B2 - Liquid ejection device and ejection method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid ejecting apparatus and an ejecting method for ejecting a liquid containing an adhesive, various paste materials and the like with or without a filler as required, In addition to enhancing the liquid draining property when the liquid ejection is stopped, the liquid dripping is prevented after the ejection is stopped, and at the same time, the cycle time of the ejection cycle is shortened to improve the work efficiency.

[0002]

2. Description of the Related Art Liquid ejecting devices of this type, which eject liquid stored in a syringe by supplying pressure thereto, and prevent unexpected leakage of the stored liquid by supplying negative pressure, have been conventionally used. The conventional discharge cycle of the liquid in the syringe of such a device is generally performed by the step of introducing a pressure force into the syringe and the step of introducing a negative pressure for holding the liquid. , Or between both of these steps by inserting a pressure-released atmospheric step.

Further, in such a liquid ejecting apparatus, when the liquid in the syringe is completely exhausted, the liquid is refilled in the syringe while the apparatus is stopped or the syringe is preliminarily filled with the liquid. It is common to replace the syringe with another syringe that is filled with liquid, and for this reason, when discharging a relatively large amount of liquid in one discharge process, frequently fill the syringe with liquid, There is a tendency to increase the capacity of the syringe for the purpose of avoiding frequent replacement of the syringe and improving work efficiency.

[0004]

By the way, in order to improve the precision of quantitative discharge of the liquid in the syringe and shorten the cycle time of the discharge cycle, the time required to pressurize the syringe to a predetermined pressure and the predetermined time are required. Whereas it is necessary to shorten the time required to reduce the pressure to the negative pressure as much as possible, when the volume of the syringe is increased, those times are inevitably long. Here, the extension of the pressurization time can be absorbed by adjusting the pressure supplied to the syringe, but regarding the depressurization time, the conventional technology of naturally discharging the pressurization pressure in the syringe to the atmosphere and the pressurization pressure It was practically impossible to effectively reduce the negative pressure for holding the liquid directly into the syringe by any of the conventional techniques by omitting the atmospheric discharge.

That is, in the former case in which the syringe internal pressure is discharged to the atmosphere, in principle, the discharge rate is specified based on the pressure difference between the atmospheric pressure and the syringe internal pressure, so that the syringe capacity is large. In this case, it is inevitable to extend the exhaust pressure time due to the volume expansion of a large amount of pressurized gas in the syringe, and in the latter case where a negative pressure for retaining liquid is supplied into the syringe, the negative pressure When the pressure is a small negative pressure for holding liquid for the purpose of preventing liquid leakage, the pressure difference with the syringe internal pressure will be somewhat larger than the former, but this is also a request for shortening the discharge time. There is a large gap between the two, and it is not possible to improve poor drainage and the occurrence of dripping. On the other hand, the negative pressure supplied to the syringe is sufficient to realize rapid drainage. If the pressure is raised to the Followed, the suction of the negative pressure path in the liquid in the syringe were other problems that become unavoidable.

The present invention has been made as a result of studies aimed at solving such problems of the prior art. The purpose of the present invention is not only for a small-capacity syringe but also for a large-capacity syringe. Even in the case of the syringe, the pressure inside the syringe is discharged very quickly, and the internal pressure becomes a negative pressure for holding the liquid in a short time. High,
It is an object of the present invention to provide a liquid discharge device and a discharge method capable of preventing the liquid from dripping after the discharge is stopped and shortening the cycle time of the discharge cycle to improve the work efficiency.

[0007]

A liquid ejecting apparatus of the present invention comprises a syringe for ejecting a filled liquid, a pressurized gas supplying means for supplying a pressure for ejecting the liquid to the syringe, such as a compressor, and a syringe. A negative pressure supply means for supplying a negative pressure for holding a liquid to the syringe, and a switching valve capable of two-position or three-position for selectively connecting the pressurized gas supply means and the negative pressure supply means to the syringe. In the present invention, a pressure-absorbing means is connected to the syringe via an exhaust pressure switching valve arranged in parallel with the switching valve.

Further, according to the liquid discharge method of the present invention, a pressure is supplied to the syringe to discharge the liquid in the syringe, and a negative pressure for holding the liquid is supplied to the syringe to prevent leakage of the liquid in the syringe. In the liquid ejection method to prevent,
Simultaneously with stopping the discharge of the liquid, starting the suction of the syringe internal pressure and the supply of the liquid holding negative pressure to the syringe, and stopping the suction of the syringe internal pressure when the syringe internal pressure drops to a predetermined value. It is a feature.

Here, after a predetermined pressurizing force is supplied to the syringe for a required time and a predetermined amount of liquid is discharged, the exhaust pressure switching valve and the switching valve are respectively operated to supply the internal pressure and the compressed gas to the syringe. Relatively high suction pressure according to volume,
In other words, in addition to supplying the negative pressure, a relatively low negative pressure for holding liquid is also supplied, and the pressing force in the syringe is promptly discharged with both of these negative pressures. , When the inside of the syringe reaches the required negative pressure for holding liquid, based on the detection result of the pressure gauge etc., the discharge pressure switching valve is returned to the original position, and thereafter, until the next discharge, The pressure inside the syringe is maintained at a negative pressure for retaining liquid.

According to this, the pressing force supplied to the syringe is discharged almost instantly with a suction pressure of a magnitude corresponding to that, and thereafter, the liquid in the syringe is Since the internal pressure of the syringe can be maintained at the required negative pressure for holding liquid without fear of sucking into the suction path, liquid drainage at the time of stopping liquid discharge is greatly improved, and after the discharge is stopped. It is possible to sufficiently prevent liquid dripping, and further, it is possible to shorten the cycle time of the discharge cycle and improve the work efficiency.

Another device of the present invention is particularly one in which an opening / closing valve for controlling communication and shutoff between the switching valve and the syringe of the above-mentioned device is interposed. Here, the on-off valve may be a two-position switching valve.

Further, another method of the present invention is, in particular, at the same time when the discharge of the liquid is stopped, the suction of the syringe internal pressure is started with a relatively high suction pressure, and when the syringe internal pressure drops to a required value, The suction of the internal pressure of the syringe is stopped, while the supply of the negative pressure for holding the liquid into the syringe is started. here,
When the liquid suction is stopped, the suction pressure with a relatively high negative pressure and the negative pressure for holding the liquid with a relatively low negative pressure are used separately.
Under the action of the on-off valve, only the suction pressure is applied to the syringe, and after the syringe internal pressure is sufficiently reduced, only the liquid holding negative pressure is applied to the syringe, thereby producing the same effect as in the above case. Can bring.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of the present invention, in which a solid line shows a pressure circuit and a broken line shows a signal circuit. Here, a pressurized gas supply means 2 for supplying a pressure for discharging liquid to a syringe 1 for discharging the filled liquid, a compressor 2a in the figure, and a downstream side thereof are arranged. The regulator 2b is connected via a two-position switching valve 3 and a negative pressure supply means 4 for supplying a negative pressure for holding liquid into the syringe, a variable throttle valve 4a and its part are also shown in the drawing. Downstream ejector 4b
Is also connected to the syringe 1 via the same two-position switching valve 3, whereby the pressurized gas supply means 2 and the negative pressure supply means are operated by the operation of the two-position switching valve 3 based on the signal from the control means 5. Either one of 4 and 4 can be communicated with the syringe 1.

Here, the regulator 2b of the pressurized gas supply means 2 functions to reduce the pressure of the pressurized gas from the compressor 2a to a required pressure, and the regulator 2
The gas pressure on the downstream side of b can be measured by the discharge pressure gauge 6. Further, the variable throttle valve 4a of the negative pressure supply means 4
Controls the flow rate of the pressurized gas from the compressor 2a passing therethrough, and the ejector 4b generates a negative pressure having a magnitude corresponding to the flow rate of the passing gas. The negative pressure on the downstream side of the ejector 4b is the liquid holding pressure gauge 7
Can be measured by

Further, here, the syringe 1 is provided with a control means 5
A pressure-absorbing means 9, for example, a variable-pressure exhaust throttle valve 9a and an exhaust-pressure ejector 9b are connected via an exhaust-pressure switching valve 8 that operates based on a signal from the. Here, the exhaust pressure variable throttle valve 9a and the exhaust pressure ejector 9b are respectively
Variable throttle valve 4a and ejector 4b of the negative pressure supply means 4
, But the generated negative pressure is much larger than that of the negative pressure supply means 4.

The negative pressure on the downstream side of the exhaust pressure ejector 9b is measured by the pressure gauge 10, and the measurement result is input to the control means 5. Here, the control means 5 is based on the measurement result of the pressure gauge 10, for example, when discharge of the pressurizing force from the syringe 1 is completed and the syringe internal pressure is a required liquid holding negative pressure, that is, negative pressure supply means. When the negative pressure supplied from 4 is reached, the exhaust pressure switching valve 8 is returned to its original position.

In the constant amount discharge of the liquid in the syringe by the device configured as described above, the two-position switching valve 3 is shifted from the position shown in the figure by a signal from the control means 5.
Regulator 2b depending on the amount of liquid remaining in the syringe
Is performed by supplying the required pressurizing force adjusted in step 1 into the syringe for the required time, and when the discharge of a predetermined amount of liquid from the syringe 1 is completed, the two-position switching valve 3 is illustrated by the control means 5. And the exhaust pressure switching valve 8 is shifted from the illustrated position.

As a result, the ejector 4b of the negative pressure supply means 4 supplies, for example, a negative pressure having a relatively low negative pressure to the syringe 1 to the extent that the weight of the liquid in the syringe can be offset, and also sucks it. Ejector 9b for discharging pressure of the pressure means 9
From the above, a large negative pressure is supplied so that the pressurizing force in the syringe can be instantaneously discharged according to the size thereof, the volume of the compressed gas in the syringe, and the like.

The supply of such a negative pressure is continued until, for example, the pressure in the syringe becomes equal to the negative pressure supplied from the ejector 4b, and when the internal pressure is reached, from the pressure gauge 10 to the control means 5. Based on the feedback signal of
The control means 5 returns the exhaust pressure switching valve 8 to the illustrated position. Therefore, thereafter, the internal pressure of the syringe is maintained at the negative pressure supplied from the ejector 4b.

Thus, here, it is possible to discharge the pressing force in the syringe in an extremely short time based on the action of the pressure-absorbing means 9, which improves the liquid drainage property when the liquid discharge is stopped. It is possible to sufficiently realize the prevention of the liquid dripping after the discharge is stopped, and to shorten the cycle time of the discharge cycle to greatly improve the work efficiency.

FIG. 2 shows a three-position switching valve 3a instead of the two-position switching valve 3 of the above-mentioned device. According to this device, when the discharge of the liquid from the syringe 1 is completed, it is needless to say that the internal pressure of the syringe can be discharged in the same manner as in the previous case. 1 is in a non-communication state with respect to both the pressurized gas supply Shida 2 and the negative pressure supply means 4, while the discharge pressure switching valve 8 is operated to communicate the syringe 1 and the pressure suction means 9. Then, when the pressure in the syringe has dropped to the required pressure, the exhaust pressure switching valve 8 is returned to the position shown in the figure to stop the suction of the syringe internal pressure. It is also possible to shift the valve 3a to the position shown in the figure, and thereafter apply only the negative pressure for holding the liquid from the negative pressure supply means 4 into the syringe, which is also generated by the pressure suction means 9. Negative of negative pressure Degrees, based on it sufficiently larger than that generated by the negative pressure supplying means 4 can provide the same effect as described above.

FIG. 3 shows the device shown in FIG. 1 in which an opening / closing valve 11, in the figure, a two-position switching valve is interposed between the two-position switching valve 3 and the syringe 1, and this device also Each of the apparatus shown in FIG. 1 and the apparatus shown in FIG. 2 can be operated in the same manner as described above. That is, when the discharge of the liquid from the syringe 1 is finished, the same operation as that of the device shown in FIG. 1 is performed by the two-position switching valve 3 and the exhaust pressure switching while keeping the open / close valve 11 in the open state as shown. This can be done by switching each of the valves 8 as described above, and the same operation as described for the device shown in FIG. 2 can be achieved by shifting the three-position switching valve 3a to the neutral position by opening and closing the valve 11. Of the three-position switching valve 3a to the introduction position of the liquid holding negative pressure, the shift of the opening / closing valve 11 to the open position, simultaneously with or before the shift of the two positions. This can be performed by replacing the position opening / closing valve 3 with a shift to the introduction position of the liquid holding negative pressure.

Although the embodiment of the present invention has been described above with reference to the drawings, for example, instead of the suction means shown in the drawings, a vacuum ejector or a variable throttle valve and a positive pressure regulator may be used. Or
It can also be composed of a vacuum pump and a negative pressure regulator.

[0024]

As is apparent from the above, according to the present invention, regardless of the size of the syringe, discharge of the pressurizing force supplied to the inside of the syringe at the time of discharging the liquid can be performed very quickly. It is possible to enhance the liquid drainage property when the discharge of the liquid from the syringe is stopped, prevent the liquid from dripping after the discharge is stopped, and further shorten the cycle time of the discharge cycle, thereby greatly improving the work efficiency.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the present invention.

FIG. 3 is a circuit diagram showing still another embodiment of the present invention.

[Explanation of symbols]

1 syringe 2 Pressurized gas supply means 2a compressor 2b regulator 3 Two-position switching valve 4 Negative pressure supply means 4a Variable throttle valve 4b ejector 5 Control means 6 Discharge pressure gauge 7 Liquid holding pressure gauge 8 Exhaust pressure switching valve 9 Pressure-absorbing means 9a Variable throttle valve for exhaust pressure 9b Ejector for exhaust pressure 10 pressure gauge 11 on-off valve

Claims (5)

(57) [Claims] 1. A syringe for discharging a filled liquid, a pressurized gas supply means for supplying a pressure force for discharging the liquid to the syringe, and a negative pressure supply means for supplying a negative pressure for holding the liquid to the syringe. A liquid discharge device having a switching valve for selectively connecting the pressurized gas supply means and the negative pressure supply means to the syringe, wherein the syringe has a discharge pressure switching valve arranged in parallel with the switching valve. And a liquid ejecting device connected to a pressure absorbing means. 2. The liquid ejecting apparatus according to claim 1, wherein an opening / closing valve that controls communication and blocking between the syringe and the switching valve is interposed between the syringe and the switching valve. 3. The liquid ejection device according to claim 2, wherein the on-off valve is a two-position switching valve. 4. A liquid ejection method for supplying a pressure to a syringe to eject a liquid in a syringe and supplying a negative pressure for retaining a liquid to a syringe to prevent leakage of the liquid in the syringe. At the same time when the liquid discharge is stopped, the suction of the syringe internal pressure and the supply of the liquid holding negative pressure into the syringe are started.
A method for discharging liquid, characterized in that when the syringe internal pressure drops to a required value, the suction of the syringe internal pressure is stopped. 5. A liquid discharge method for supplying a pressure to a syringe to discharge a liquid in a syringe and supplying a negative pressure for holding a liquid to a syringe to prevent leakage of the liquid in the syringe. , The suction of the syringe internal pressure is started at the same time as the discharge of the liquid is stopped, and when the syringe internal pressure drops to a required value, the suction of the syringe internal pressure is stopped and the supply of the negative pressure for holding the liquid into the syringe is started. A method for ejecting liquid, comprising: