JPH10264411A - Liquid collecting machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent jetted micro liquid droplets from being scattered to the periphery of a measuring instrument and adhering thereto by setting a case for collecting the jetted liquid below a part for mounting a jetting member and coupling the collection case with means for generating suction force in the same direction as the jetting direction and sucking the liquid into the collection case. SOLUTION: When an ink liquid droplet P is jetted from the liquid chamber in a head 11 through a nozzle, it is irradiated continually with light from an LED light source 23 and the image thereof is picked up by means of a CCD camera 22. Falling trajectory of the ink liquid droplet P is captured as continuous points and the area thereof is measured by means of an image processor and then the volume of the liquid droplet is determined by the diameter thereof. Furthermore, a tube 26 is provided with a liquid pump 27 for generating a suction force in a collection tank 24 and sucking the ink liquid droplet P jetted from the nozzle in the collection tank 24. Micro ink liquid droplets P jetted from the head 11 are sucked forcibly into the collection tank 24 thus preventing ink liquid droplets from being scattered to the periphery of a measuring instrument and adhering thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid collecting machine, and more particularly, to a liquid collecting device provided in a measuring device for measuring the performance of minute ink droplets ejected from an ejection hole such as an ink jet head. The present invention relates to a liquid collecting machine for collecting ink droplets.

[0002]

2. Description of the Related Art Generally, in an ink jet printer, an ink jet head (hereinafter, simply referred to as a head) is used.
By ejecting ink droplets from the nozzles formed on the recording paper onto the recording paper, an image is formed on the recording paper. The quality items of this image include dot density, dot position accuracy, density unevenness, sharpness, etc. Is mentioned.

[0003] The dot density in the above-mentioned quality items is typically about 300 DPI. However, in order to increase the dot density to 400 DPI and 600 DPI in order to increase the resolution of an image, the dot density for determining the dot density is required. It is necessary to reduce the pitch and the dot diameter. It is known that the dot diameter has a linear function with the volume of the ink droplet ejected from the head, and that the dot diameter increases as the ejection speed of the ink droplet increases.

As shown in FIG. 5, when the scanning direction of the head 1 is set in the direction of the arrow, two components of the main scanning direction and the sub-scanning direction (see FIG. 5). Δx · Δy), and this component exists in each of the printer and the head 1. Also,
Since the components of the printer are determined by the mechanical accuracy, the error is relatively small. However, the components of the head 1 have a large contribution ratio of the particleization characteristic, and factors of this characteristic include ejection direction accuracy and ink droplets. There is speed fluctuation.

[0005] The accuracy of the injection direction mostly depends on the processing accuracy and quality of the nozzle 1a except for disturbances such as dust. The most significant factor among them is the ink droplet velocity fluctuation, which fluctuation appears only in the main scanning direction (Δx). The allowable value of the dot misalignment is usually １ ／ of the dot pitch.
This is about 1/2 (usually about 80 μm in the case of 300 DPI), and this allowable value is a very strict value.

Therefore, in order to obtain an image having a high resolution, it is necessary to control the volume of the ejected ink droplet, the ejection speed of the ink droplet, and the accuracy of the ink ejection direction with high accuracy. Therefore, it is necessary to sufficiently measure the performance of the ejected ink droplet by previously measuring the volume of the ejected ink droplet, the ejection speed of the ink droplet, and the accuracy of the ink ejection direction.

Among the above-mentioned performances, a method for measuring the volume of an ink droplet is described in, for example, Japanese Patent Application Laid-Open No. 6-317.
No. 452, for example. This measurement method measures the total amount of ink droplets by measuring the mass of this container after receiving the ink droplets ejected at a constant frequency for a fixed time in a container containing a non-volatile solvent, and ejecting this total amount. Divided by the total number of ink droplets. Next, the mass per droplet of the jetting liquid is determined, and the volume of the ink droplet is determined from this mass.

As another measuring method, an ink droplet ejected from a head is captured as an image by a CCD camera, an area of the image is obtained by an image processing device, and a diameter of the ink droplet is obtained from the area. In some cases, the volume of an ink droplet is determined by the following method.

[0009]

However, in the former measurement method, ink droplets ejected at a constant frequency for a fixed time are received by a container containing a non-volatile solvent. When the droplets reach the non-volatile solvent, there is a problem that a part of the ink droplets pops and becomes mist-like and scatters, and scatters around the measuring device.

[0010] In particular, when the ink liquid used in the ink jet printer is alkaline, when a part of the ink droplets become mist and scatter and adhere around the measuring device, the measuring device erodes. As a result, the reliability of the measuring device cannot be maintained for a long time. Also,
In the latter measurement method, a container for collecting ink droplets ejected from the head is required, but if this container is close to the head, the ink droplets that collide with the container pop and scatter as mist. In addition, it scatters to the CCD camera and peripheral devices, and when the head and the container are close to each other, there is a problem that workability when mounting the head on the measuring device is extremely poor.

On the other hand, it is conceivable to arrange the container at a position far from the head in order to improve the workability when the head is mounted on the measuring device. In this case, the ink droplets reach the container. By this time, ink droplets are scattered due to minute fluctuations of air around the measuring device, and the ink droplets scatter around the measuring device. Therefore, even in such a case, the ink adheres to the measuring device and the device erodes, and the reliability of the measuring device cannot be maintained for a long time.

Further, such a problem similarly occurs even if the device for measuring the ink droplet ejection speed or the ink ejection direction is replaced with a device for measuring the ink droplet ejection speed or the ink ejection direction instead of the measurement device for measuring the volume of the ink droplet. Was. Therefore, the present invention can prevent the minute liquid ejected from the ejecting member from scattering and adhering around the measuring device, and can prevent the measuring device from eroding. It is an object of the present invention to provide a liquid recovery machine capable of maintaining reliability for a long time.

[0013]

According to the first aspect of the present invention,
In order to solve the above-mentioned problem, a measurement is performed in which an ejection member having at least one or more ejection holes formed so as to eject a minute liquid is attached to an attachment portion, and characteristics of the liquid ejected from the ejection member are measured. In a liquid recovery machine provided in the apparatus and recovering the liquid ejected from the ejection member, a collection container provided below the mounting portion for collecting the liquid ejected from the ejection member is connected to the collection container. And a suction unit for generating a suction force in the same direction as the liquid ejection direction to suck the liquid ejected from the ejection member into the collection container.

In this case, since the minute liquid ejected from the ejecting member is forcibly sucked into the collection container by the suction means, the minute liquid ejected from the ejecting member scatters and adheres around the measuring device. Can be reliably prevented. As a result, the measurement device can be prevented from being eroded by the liquid, and the reliability of the measurement device can be maintained for a long period of time.

According to a second aspect of the present invention, in order to solve the above-mentioned problem, in the first aspect of the present invention, there is provided an elevating means for elevating and lowering the collection container so as to be able to approach and separate from the mounting portion. It is characterized by. In that case,
When attaching the ejection member to the attachment portion, the collection container is separated from the attachment portion by the elevating means, thereby forming a wide working space between the attachment portion and the collection container, and the ejection member is attached to the attachment portion. Installation work can be performed favorably.
After the ejection member is attached to the attachment portion, the collection container is brought closer to the ejection member by the elevating means, thereby securing a sufficient space between the ejection member and the collection container for measuring the properties of the liquid. can do. This space is a space for photographing liquid with a CCD camera.

According to a third aspect of the present invention, in order to solve the above-mentioned problems, in the first or second aspect of the present invention, an adjusting means for adjusting a suction force of the suction means is provided. In such a case, when measuring the ejection direction and ejection speed of a minute liquid, if the liquid is sucked with a very strong suction force, the actual speed and direction of the liquid cannot be accurately measured. By adjusting the suction force so as not to affect the measurement of the direction, it is possible to prevent a measurement error from occurring.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 to 4 are views showing one embodiment of a liquid recovery machine according to the present invention, and show an example in which the liquid recovery machine is applied to a recovery machine that recovers minute ink droplets ejected from an inkjet head. I have.

First, the configuration will be described. In FIG. 1A, reference numeral 11 denotes a head (ejection member).
A main body 12 in which a liquid chamber 14 filled with ink (liquid) 13 is formed, a piezo vibrator 15 provided in an upper part of the main body 12, and a nozzle (which ejects the ink 13 as minute ink droplets) Injection holes) 16. An ink tank 18 filled with supply ink 17 is connected to the main body 12 of the head 11 via a supply pipe 19, and the supply pipe 19 is connected to a supply hole 12a. It is sufficient that at least one nozzle 16 is provided.

Here, a method of ejecting ink droplets will be described. The head 11 is set so that the inside of the liquid chamber 14 is at a negative pressure with respect to the atmospheric pressure, and for this purpose, the position of the ink tank 18 is set at a predetermined position with respect to the head 11. . For this reason, as shown in FIG. 1B, the ink meniscus M of the nozzle 16 has a concave spherical shape.

Then, a piezo oscillator 15 is provided in accordance with the image signal.
When a pulse-like electric field is applied to the liquid crystal, the piezo vibrator 15 is deformed toward the inside of the liquid chamber 14 and rapidly pressurizes the ink in the liquid chamber 14. At this time, the ink 13 in the liquid chamber 14 moves in both directions of the nozzle 16 and the supply hole 12a, and the ink that has moved to the nozzle 16 becomes a column and is ejected from the opening of the nozzle 16 into the atmosphere.

On the other hand, the ink on the supply path 12a side moves in the reverse direction, so that a large negative pressure is suddenly generated in the liquid chamber 14. As a result, the ink at the opening of the nozzle 16 is pulled back,
Cutting in the ink occurs, and the leading end portion flies as ink droplets. At this time, a meniscus is formed in the opening of the nozzle 16 in such a manner that air is largely sucked. Then, the internal pressure of the liquid chamber 14 returns to the positive pressure again, and the meniscus at the opening of the nozzle 16 is also pulled back in the opening direction of the nozzle 16 by the surface tension of the ink, so that the ink is refilled. Thereafter, the ink meniscus vibrates attenuated with the initial position as an equilibrium point.

Next, a measuring device provided with an ink collecting machine (liquid collecting machine) according to the present embodiment will be described with reference to FIGS. 2 and 3, reference numeral 21 denotes a bracket (mounting portion).
The head 11 is mounted on the bracket 21 such that the nozzle 16 faces down. A CCD camera 22 and an LED light source 23 are provided near the head 11, and an image of the ink liquid is taken by the CCD camera 22 and the LED light source 23.

That is, when the ink droplet P is ejected from the inside of the liquid chamber 14 of the head 11 through the nozzle 16 by driving the piezoelectric vibrator 15, the ink droplet P
By irradiating light intermittently from 23, the ink droplet P at this irradiation is photographed by the CCD camera 22. As a result, the image captured by the CCD camera 22 is regarded as a point where the state of the drop of the ink droplet P is continuous.

The area taken from the image taken by the CCD camera 22 is measured by an image processor (not shown), and the diameter of the ink droplet can be obtained by calculating the diameter of the ink droplet from the area. ing. On the other hand, a collecting container 24 is provided below the bracket 21, and the collecting container 24 collects the ink droplets P ejected from the nozzles 16. The collection container 24 is attached to an air cylinder (elevating means) 25, and is moved up and down by the air cylinder 25 so as to be able to approach and separate from the bracket 21.

In the center of the bottom of the collection container 24, a tube is provided.
One end of the tube 26 is attached, and the other end of the tube 26 is inserted into the ink storage tank 28. The tube 26 is provided with a liquid pump 27,
Numeral 27 generates a suction force in the collection tank 24. Also, since one end of the tube 26 is attached to the center of the bottom of the collection container 24, the liquid pump 27
A suction force is generated in the same direction as the ejection direction of the ink droplets P in the inside to collect the ink droplets P ejected from the nozzles 16 in the collection container 24.
Can be sucked into. Then, the sucked ink droplet P is returned to the storage tank 28 through the tube 26. In the present embodiment, the tube 26 and the liquid pump 27
Constitute suction means.

A flow control valve (adjustment means) 29 is provided between the liquid pump 27 and the recovery container 24. The flow control valve 29 is constituted by a variable throttle valve or the like, and the suction force of the liquid pump 27 is provided. (That is, the amount of air suction) is adjusted. In the present embodiment, the collection container 24, the air cylinder 25, the tube 26, the liquid pump 27, the storage tank 28, and the flow control valve 29 constitute an ink collection machine.

Next, a method for measuring the volume of the ink droplet P will be described with reference to the flowchart of FIG. Note that this flow is executed by a controller (not shown) provided in the present measurement device, and the controller performs the main measurement such as driving the air cylinder 25 and the piezoelectric vibrator 15 and giving an image measurement command to the image processing device. The control required for the device is executed.

In an initial state before the operation is started, the collection container 24 is separated downward from the bracket 21 by the air cylinder 25, and a wide working space is formed between the bracket 21 and the collection container 24. Then, to start measurement, first, set the nozzle 16
The head 11 is mounted on 21 (step S1). Next, the collection container 24 is raised by the air cylinder 25 so as to be close to the head 11, and when a sufficient space for measuring the area of the ink droplet P is secured between the head 11 and the collection container 24, the rising is performed. It stops (step S2).

Next, after the operation of the liquid pump 27 is started (step S3), the ink droplet P is ejected from the inside of the liquid chamber 14 of the head 11 through the nozzle 16 by driving the piezoelectric vibrator 15 (step S4). . Next, the ink droplets P are intermittently irradiated with light from the LED light source 23, so that the ink droplets P at the time of the irradiation are photographed by the CCD camera 22, and the area of the image photographed by the CCD camera 22 is calculated as an image. It is measured by a processing device. Then, the diameter of the ink droplet is obtained from the area, and the volume of the ink droplet P is obtained from the diameter and the density of the ink droplet (step S5).

Next, it is determined whether or not the volume measurement has been completed (step S6). When it is determined that the measurement has been completed, the driving of the piezoelectric vibrator 15 is stopped to stop the ejection of the ink droplets P ( Step S7). Also, the nozzle 16 of the head 11
When the ink droplets P are ejected from the storage tank 28, the ink droplets P are forcibly sucked into the collection container 24 by the liquid pump 27 and returned to the storage tank 28 via the tube 26.

Next, after the driving of the liquid pump 27 is stopped (step S8), the collection container 2 is moved by the air cylinder 25.
4 to lower the collection container 24 to the bracket 21
The head 11 is detached from the bracket 21 (step S10), and the measurement operation is completed. As described above, in the present embodiment, the collection container 24 for collecting the ink droplets P ejected from the head 11 is provided below the bracket 21, and the collection container 24 is suctioned in the same direction as the ejection direction of the ink droplets P. Generating head 11
Since the liquid pump 27 that sucks the ink droplets P ejected from the head 11 into the collection container 24 is provided, the minute ink droplets P ejected from the head 11 can be forcibly sucked into the collection container 24, It is possible to reliably prevent the ink droplets P ejected from the head 11 from scattering and adhering around the measuring device (such as the CCD camera 22 and the LED light source 23). As a result, the measurement device can be prevented from being eroded by the ink droplets P, and the reliability of the measurement device can be maintained for a long period of time.

An air cylinder that raises and lowers the collection container 24 so that it can approach and separate from the bracket 21.
When the head 11 is mounted on the bracket 21, the air cylinder 25 separates the collection container 24 from the bracket 21 to form a wide working space between the bracket 21 and the collection container 24. Therefore, the operation of attaching the head 11 to the bracket 21 can be performed favorably. After the head 11 is mounted on the bracket 21, the collection container 24 is moved to the head by the air cylinder 25.
Head 11 and collection container
During the period 24, a sufficient space for photographing the ink droplets P by the CCD camera 22 can be secured.

Further, since the flow adjusting valve 29 for adjusting the air suction amount of the liquid pump 27 is provided, it is possible to prevent a measurement error of the ink droplet P from occurring. That is, in the present measuring device, when measuring the ejection direction and the ejection speed of the ink droplet P, when measuring the ejection direction and the ejection speed of the minute ink droplet P, the ink When the droplet P is sucked, the actual speed and direction of the ink droplet P cannot be accurately measured.
By adjusting the suction force so as not to affect the measurement of the speed and direction of the ink droplet P, it is possible to prevent a measurement error of the ink droplet P from occurring.

In this embodiment, the suction means is constituted by the liquid pump 27. However, the present invention is not limited to this, and air suction by a fan or air suction by a vacuum pump may be employed. Further, although the elevating means is constituted by the air cylinder 25, it is not limited to this, and may be constituted by a hydraulic cylinder or the like.

Further, in the present embodiment, the liquid recovery device is applied to a device for recovering the ink droplets P ejected from the head 11, but any other liquid recovery device may be used as long as it recovers minute liquid. Needless to say, it can be applied to.

[0036]

According to the first aspect of the present invention, since the minute liquid ejected from the ejection member can be forcibly sucked into the collection container by the suction means, the minute liquid ejected from the ejection member can be forcibly sucked. The liquid can be reliably prevented from scattering and adhering around the measuring device. As a result, the measuring device can be prevented from being eroded by the liquid,
The reliability of the measuring device can be maintained for a long time.

According to the second aspect of the present invention, when the jetting member is mounted on the mounting portion, the collection container is separated from the mounting portion by the elevating means, so that a wide space is provided between the mounting portion and the collection container. The work space is formed, and the work of attaching the ejection member to the mounting portion can be performed favorably. After the ejection member is attached to the attachment portion, the collection container is brought closer to the ejection member by the elevating means, thereby securing a sufficient space between the ejection member and the collection container for measuring the properties of the liquid. can do.

According to the third aspect of the invention, when measuring the ejection direction and ejection speed of a minute liquid, if the liquid is sucked with a very strong suction force, the actual speed and direction of the liquid can be accurately measured. Therefore, by adjusting the suction force so as not to affect the measurement of the speed and direction of the liquid, it is possible to prevent a measurement error from occurring.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a liquid recovery device according to the present invention, wherein (a) is a cross-sectional view of a head applied to the liquid recovery device, and (b) is an A in FIG. It is an enlarged view of the part shown, and is a cross-sectional part of the nozzle part in which the meniscus was formed.

FIG. 2 is a view showing one embodiment of a liquid recovery device according to the present invention, and is a perspective view of a measuring device provided with the liquid recovery device.

FIG. 3 is a schematic front view of a measuring device provided with a liquid recovery device according to one embodiment.

FIG. 4 is a flowchart illustrating a method for measuring the volume of an ink droplet according to one embodiment.

FIG. 5 is a diagram for explaining the dot position accuracy of a head and ink droplets ejected from the head.

[Explanation of symbols]

 11 Head (ejection member) 16 Nozzle (ejection hole) 21 Bracket (mounting part) 24 Collection container 25 Air cylinder (elevation means) 26 Tube (suction means) 27 Liquid pump (suction means) 29 Flow control valve (adjustment means)

Claims (3)

[Claims] At least one such that a minute liquid is ejected.
A liquid recovery device which is provided in a measuring device which mounts an ejection member having at least one ejection hole on a mounting portion and measures characteristics of a liquid ejected from the ejection member, and collects the liquid ejected from the ejection member. In the machine, provided below the mounting portion, a collection container for collecting the liquid ejected from the ejection member, connected to the collection container, to generate a suction force in the same direction as the liquid ejection direction, And a suction means for sucking the liquid ejected from the ejection member into the collection container. 2. The liquid recovery machine according to claim 1, further comprising a lifting means for raising and lowering the recovery container so as to be able to approach and separate from the mounting portion. 3. The liquid recovery machine according to claim 1, further comprising adjusting means for adjusting a suction force of said suction means.