JPH0420054Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Field of Industrial Application The present invention relates to an inkjet printer that prints a desired image by depositing minute ink droplets or the like.

(b) Prior Art It is widely known that the biggest drawback of ink droplet ejecting devices is that the orifice through which ink droplets are ejected is clogged, and various proposals have been made to prevent such clogging. ing.

3 and 4 are cross-sectional views for explaining a clogging prevention method for which the applicant has already applied for a patent and published the application as Japanese Patent Application Laid-open No. 14757/1983.
In both figures, 1 is an on-demand type ink droplet ejecting device, and the ink droplet ejecting device 1 includes a piezoelectric diaphragm 2 that curves and vibrates in response to an image signal, and a piezoelectric diaphragm 2 with a long axis. A horn-shaped pressure chamber 3 arranged in a side opening, a thin plate-shaped vibrator 4 provided on the short diameter side of the pressure chamber 3 so as to be able to freely vibrate, and an ink chamber that holds ink in the front of the vibrator 4. 5, a front plate 6 facing the vibrator 4 with the ink chamber 5 in between, and a first orifice 7 with a minute diameter bored at a portion of the front plate 6 facing the vibration center of the vibrator 4. , has
Further, an air layer 8 consisting of a thin air layer 8a and an air rectifying layer 8b is provided in front of the first orifice 7, and a hole is opened from the thin air layer 8a of the air layer 8, and a hole is formed from the first orifice 7. The second orifice 10 has an opening diameter twice or more larger than the first orifice 7 through which the ejected ink droplets 9 pass. Reference numeral 11 denotes an ink tank that supplies ink to the ink chamber 5 of the ink droplet ejecting device 1, and contains several hundred c.c. in a bag made of polymer film or the like with low air permeability.
Contains ink. 12 is an ink supply pipe connecting the ink tank 11 and the ink chamber 5;
3 is an ink coupler inserted in the middle of the ink supply pipe 12, and the ink supply pipe 12 extending from the ink tank 11 can be freely attached to the ink coupler 13, and ink can be replenished by replacing each ink tank 11. It is enforced. Reference numeral 14 denotes an air pump that appropriately adds an air flow 16 as shown by the arrow to the air layer 8 and ink tank 11 of the ink droplet ejecting device 1 through an air supply pipe 15.
and a thin air layer 8a of the air layer 8 of the ink droplet ejecting device 1.
and an air flow 1 supplied to the thin air layer 8a.
an annular air rectifying layer 8b that rectifies air from the periphery of the air;
A valve device 17, for example, a three-way solenoid valve, is provided in the air supply pipe 15. The valve device 17 is an air pump 14 during printing operation.
and the thin air layer 8a are brought into communication with each other, and both are set in a disconnected state during non-printing operations. A recording medium 18 is placed at a short distance in front of the second orifice 10 of the ink droplet ejecting device 1 during the printing operation in FIG. be done.

FIG. 4 shows the state in which ink is filled into the thin air layer 8a of the ink droplet ejecting device 1 during non-printing operation. That is, the second orifice 10 is covered with a lid 20 made of an elastic material such as rubber, and the valve device 17 cuts off communication between the air pump 14 and the air layer 8 and opens the air layer 8. When the air pump 14 is operated to pressurize the ink in the ink tank 11, the pressure of the ink in the ink chamber 5 of the ink droplet ejecting device 1 also increases, and the ink that was in an equilibrium state in the first orifice 7 finally rises. flows out from the high-pressure ink chamber into the air layer 8. A piezoelectric diaphragm 2 is used to assist this ink flow.
When an electric signal is applied to the oscillator 4 to cause the vibrator 4 to continuously vibrate in a curved manner, the balance of the ink is immediately disrupted and the ink begins to flow from the first orifice 7 into the air layer 8 .
Once the ink starts to flow, even if the application of the electrical signal to the piezoelectric diaphragm 2 is stopped, the pressure in the air layer 8 (air pressure) is lower than the ink pressure in the ink chamber 5, so the supply of the ink continues. . In this way, the first orifice 7 is covered with ink supplied into the air space 8. This supply of ink is detected by suitable detection means 24, for example the body 22 of the ink drop ejector 1.
It is controlled by detecting the resistance value between the air supply pipe 15 and the detection electrode 23 in the insulated air supply pipe 15.
That is, when the ink rises inside the air supply pipe 15 and immerses the detection electrode 23, the body 22 and the detection electrode 2
The resistance value between 3 and 3 is drastically reduced by the ink, and the end of ink filling is detected.

Further, if the vibration of the piezoelectric diaphragm 2 is continued until the filling is completed, the ink filling is not only done quickly but also completely, so this method is usually adopted.

When the detection means 24 detects that the air layer 8 has been filled with ink, the air pump 14 stops operating and the pressure in the ink tank 11 gradually decreases.
On the other hand, the air layer 8 is in communication with the outside air via the air supply pipe 15, and when the pressure of the ink tank 11 decreases as described above in this state, the ink supplied and filled into the air layer 8 is transferred to the ink tank 11. The valve device 17 is closed in order to allow the flow to flow backwards. Therefore, the system of the air layer 8 and the air supply pipe 15 is closed, and the backflow of ink is prevented by the so-called Torricelli principle.

As a result, the ink droplet ejecting device 1 is in a state where the air layer 8 is filled with ink in the home position indicated by (HP) in FIG. 5 during non-printing operation, and the first orifice 7 is Since it is covered with ink, clogging mainly caused by drying and adhesion of dust is prevented.

In this way, ink is supplied into the air layer 8 at the home position (HP) and the ink is supplied to the first orifice 7.
Ink droplet ejecting device 1 where clogging was prevented
is moved to the standby position (SP) and faces the gutter 21 prior to the printing operation. In this state, operate the valve device 17 to connect the air pump 14 and the air layer 8.
At the same time, the air pump 14 is operated. Then, the ink filled in the air layer 8 flows into the air flow 16 as shown by the arrow in FIG.
The liquid is pressurized from the outer circumferential direction by the cylinder, and is discharged from the second orifice 10 which is opened at the center.
This discharged ink is captured by the gutter 21 disposed opposite to each other. When the ejection operation is completed, the air flow 16 is stopped, the ink is balanced in the first orifice 7, and the ink droplet ejecting device 1 is in a standby state.

(c) Problems to be solved by the invention By the way, in such an inkjet printer, the ink droplet ejecting device 1 is usually installed in a limited space, so the air supply system is also shown in FIG. Therefore, it is necessary to use the bent tube 25 to make it compact.

In an inkjet printer configured in this way, when filling with filling liquid to prevent clogging,
When the filling liquid enters the bent tube 25, the filling liquid remains inside the bent tube 25 even after the filling liquid is discharged, and this obstructs the supply of air flow during printing.

In addition, air supply pipe 1 is installed to prevent backflow of filling liquid.
When the tube 5 was provided with a vent, there were problems such as the filling liquid overflowing from the vent to the outside of the tube.

Therefore, the detector 24 is provided between the ink droplet ejecting device 1 and the bent tube 25 to prevent the filling liquid from entering the bent tube 25, but the detector 24 is arranged at such a location. is difficult due to spatial issues. Moreover, since the detector 24 is a current-carrying type detector 24, the filling liquid may be electrolyzed, even though the current is weak, and this may adversely affect the prevention of clogging.

(d) Means for solving the problems The present invention is an inkjet printer that prevents clogging of the first orifice by filling an air layer with an anti-clogging liquid during non-printing operations. The air flow generation source supplied to the ink droplet ejecting device is connected to the ink droplet ejecting device by an air supply pipe having a bent tube, and a spiral air supply pipe is used for the air supply pipe near the ink droplet ejecting device. shall be.

(e) Effects According to the present invention, the filling liquid can be held in the spiral air supply pipe, and can be prevented from entering into the bent pipe or the like.

(f) Example An example of the present invention will be described below with reference to FIGS. 1 and 2. Incidentally, the same parts as those in the conventional example are given the same reference numerals, and the description thereof will be omitted.

The present invention connects the air pump 14, which acts as an airflow source, to the air layer 8 of the ink droplet ejecting device 1 through an air supply pipe 15. This air supply pipe 15 uses a spiral air supply pipe 30 near the ink droplet ejecting device 1. That is,
The main body of the air supply pipe 15 and the ink droplet ejecting device 1 are connected via a spiral air supply pipe 30. Further, the air supply pipe 15 is provided with a vent hole 22 to prevent backflow of the filling liquid.

When the filling operation is performed for a predetermined period of time during non-printing to fill the air layer 8 with the filling liquid, the filling liquid is retained by the spiral air supply pipe 30.

(G) Effects of the invention As mentioned above, since the filling liquid is retained by the spiral air supply pipe, there is no fear that the filling liquid will penetrate into the bent pipe. Moreover, for this reason, the detector can be omitted. Furthermore, since a spiral air supply pipe is used, it can be installed even in a narrow space, and assembly is easy.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention; FIG. 1 is a cross-sectional view showing a non-printing operation, and FIG. 2 is a perspective view of the main part. 3 to 7 show conventional examples, FIG. 3 is a cross-sectional view showing the printing operation, FIG. 4 is a cross-sectional view showing the ink filling operation, and FIG. 5 is a cross-sectional view showing the operation of the ink droplet jetting device FIG. 6 is a schematic view showing the position, FIG. 6 is a sectional view showing the ink discharge operation, and FIG. 7 is a perspective view of the main part. DESCRIPTION OF SYMBOLS 1... Ink droplet ejecting device, 7... First orifice, 8... Air layer, 10... Second orifice, 14... Air pump, 15... Air supply pipe,
17... Valve device, 25... Bent pipe, 30... Spiral air supply pipe.

Claims (1)

[Claims for Utility Model Registration] First and second coaxially arranged with an air layer in between
The ink droplets ejected from the first orifice during the printing operation are directed from the outer periphery of the air layer toward the second orifice through an air flow supplied from an air flow source to the second orifice. an ink droplet ejecting device that causes the ink droplets to fly from the second orifice, and fills the air layer with an anti-clogging liquid within the operating time of the air flow generation source during non-printing operations to prevent clogging of the first orifice; An inkjet printer comprising: the air flow source and the ink droplet ejecting device being connected by an air supply pipe having a bent pipe;
An inkjet printer characterized in that a spiral air supply pipe is used as the air supply pipe near the ink droplet ejecting device.