JPH0126344B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ink jet recording apparatus that performs recording by jetting ink pressurized by a pump from a nozzle at a set pressure.

FIG. 1 shows a conventional example of this type, in which ink is supplied from an ink container 1 to an ink tank 2, is pressurized by a pump 3, and then passes through a conduit 4 to a nozzle of a recording unit 5. Injected. Further, a pressure regulator 10 is disposed in the middle of the conduit 4 to open and close the port 6 according to the difference between the set load W applied to the pressurizing shaft 8 by an O-ring 7 and the ink pressure. Therefore, when the pressure of ink sent from the pump 3 to the recording section 5 increases, the pressurizing shaft 8 and the O-ring 7 are pushed up to open the port 6 and the ink is sent to the pipe line 9.
The ejection pressure of the ink is adjusted by releasing the ink to the pump 3 via the ink. However, in this device, the pump 3 sends ink to the recording section 5 at the same time as recording starts, but since the pipe line 4 and the recording section 5 are made of pressure-resistant elastic material, it takes time to raise the internal pressure. However, because of the large resistance of the nozzles, especially when the conveyance speed of the recording paper is increased, recording is not made for a while after the start of conveyance, and a certain amount of ink is ejected gradually and then a certain amount is ejected. Furthermore, it is necessary to supply power to the solenoid that presses the spring in order to apply the load W, and power consumption increases proportionally, especially when setting pressures in multiple stages.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an ink jet recording apparatus that can draw clear waveforms immediately after the start of recording with little power consumption, and can quickly stop the writing.

Next, the present invention will be explained based on an embodiment of the present invention shown in FIG.

An ink tank 12 supplied with ink from an ink container 11 supplies ink to a pump 14 through a conduit 13, and this pump 14 receives ink pressure detected by a pressure sensor 17 attached to an ink delivery conduit 16. The drive motor is controlled according to the comparison output of the comparator 18 with the set value and the ink at the set pressure is delivered. Sending pipe line 16
Further, an accumulator 20 for removing the pulse pressure of the pump 14 and increasing the capacity is disposed, and a recording section 26 having a nozzle 25 is passed through the accumulator and the solenoid valve 30 for pressure switching according to the present invention.
Ink is pumped from the pump 14 to.

This pressure switching solenoid valve 30 has a solenoid 31
Valve chambers 32 and 33 are arranged opposite to each other on both sides, and the valve chamber 32 is connected to the delivery conduit 16 and the conduit 27 to the recording section 26, while the valve chamber 33 is connected to the ink return conduit 15. are connected to each other, and both valve chambers 32 and 33 are communicated through a conduit 35. The ports 36 to the delivery line 16 in the valve chamber 32 and the ports 37 to the line 35 in the valve chamber 33 are connected to plungers 41 and 4 which are urged outwardly toward each other by a spring 40.
1' and each having a diaphragm 44 and 44', a mutually coaxial valve body 45;
and 45', and when the solenoid 31 is energized, these valve bodies 45, 4 are closed.
5' are opened by being drawn inwardly along guides 46, 46', respectively. Further, as can be seen from the figure, the effective pressure receiving surface of the valve body in the opening direction formed by the valve body 45 itself and its diaphragm 44 is smaller than the effective area when closed (i.e., compared to the cross-sectional area of the port 36). ) It is very wide. That is, in a predetermined ink pressure range, the valve body 45
Once the pressure receiving surface of the solenoid 31 is opened, it receives a large pressing force in the opening direction corresponding to the area ratio, and the solenoid 31
remains open even in the de-energized state. In other words, the spring 40 resists the pressure of the port 36 in the opening direction corresponding to the cross-sectional area of the port 36 under the set pressure.
6 can be closed, but the pressure force corresponding to the pressure receiving surface when opened is set to be strong enough to open the port 36.

When recording, the internal pressure of the delivery pipe line 16 is raised in advance, and the pump 14 is driven in advance to accumulate pressure in the accumulator 20.
When the internal pressure detected by 7 reaches the set pressure, the motor drive of the pump 14 is stopped. During this time, the port 36 of the valve chamber 32 is closed by the valve element 32, which is pressed by the spring 40 due to its small cross-sectional area. In this state, when the solenoid 31 is momentarily excited for about 10 ms by a solenoid excitation means (not shown), the plungers 41 and 41' are attracted inwardly against each other against the spring force. Ports 36 and 37 are opened. Therefore, ink flows into the valve chamber 32 and instantaneously increases its internal pressure, and the spring 40 is applied with a large force proportional to the effective pressure receiving surface in the opening direction.
Press inward. On the other hand, the valve chamber 33 communicates with the ink tank 12 under atmospheric pressure through the pipe line 15.
Furthermore, since the valve chamber 32, where the internal pressure has increased, is communicated via the conduit 35, the pressure can hardly increase instantaneously. Therefore, when the solenoid 31 is de-energized, the port 37 on the valve chamber 33 side immediately closes, but the valve body 45 on the valve chamber 32 side remains retracted from the position of the port 36 against the spring force. , ink is continuously ejected from the nozzles 25 of the recording section 26. That is, pressurized ink enters the valve chamber 32 at the same time as the valve body 45 is opened, and is immediately injected from the injection nozzle 25, while passing through the conduit 35 and closing the port 37 of the valve chamber 33. .

When recording is stopped, if the solenoid 31 is energized for a longer period, for example, 0.5 seconds, than when recording is started, the valve chamber 32 is routed through the conduit 35, the port 37, the valve chamber 33, and the conduit 15 in order to open the port 37 for a longer time. The nozzle 25 is connected to the tank 12 under atmospheric pressure, so that the pressure in the recording section 26 suddenly drops, and ink can no longer be ejected from the nozzle 25 having a small pipe diameter. When the solenoid 31 is energized, the valve chamber 32
Since the internal pressure of the valve body 45 is also decreasing, the valve body 45
The pressing force returns the port 36 to the position where it is closed.

Although the valve chamber 33 has the same structure as the valve chamber 32, it is not necessary to provide the above-mentioned self-holding function, and the pressure receiving surface when opened may be made smaller.
In this case, the connection ports with the conduits 35 and 15 can also be exchanged. Further, the valve chamber 32 may have two ports, and the port of the pipe line 27 may be shared with the pipe line 35.

FIG. 3 shows a specific structural example of the solenoid valve 30 in FIG.
Except for this, identical structural parts are assembled on both sides of the solenoid 51 and placed oppositely. 52 is a valve chamber case having three slots 54, 55 and 56 communicating with the outside from a cylindrical cavity 53 for forming a valve chamber. Slots 54, 55, 56
The outer end of each of the slots 55 has a larger diameter to fit the external conduit, and the inner end of the slot 55 has a smaller diameter opening into the ridge of the cavity 53.
Note that the elastic body 61 attached to the tip of the valve body 60
is for alleviating wear caused by contact with the facing port 62. Prepare two such valve chamber cases 52, insert the valve body 60 fitted with the diaphragm 65 into each cavity 53, insert the guide 67 from behind, and close the valve chamber cases 52 around the flanges. Fit the edge of the The cavity 53 is thereby formed as a valve chamber and connects the plungers 50 and 50' to the rear end of each valve body 60. Both plungers 50 and 50' are connected to the solenoid 5 with the spring 63 housed in the recessed portion at the rear end of each plunger.
1 into the hole in the bobbin 68 from both sides. Then, the guide 67 is fitted into the edges 66 and 66' at both ends of the plate-shaped external metal fitting 64, and at the same time, the bobbin 68 of the solenoid 51 is attached to a mounting portion (not shown) of the plate-shaped external metal fitting 64. In addition, the slot 56 in the right valve chamber
is covered in advance, and the slot 56 of the left valve chamber and the slot 54 of the right valve chamber are communicated through a pipe.

When in use, the slot 55 in the left valve chamber is connected to the pipe line 1.
6 and slot 54 connects to line 27, and slot 54 in the right valve chamber connects to line 15.
Note that the flange 67 of the plunger 50 is for restricting the retreat position of the valve body 60 due to the pressurized ink.

FIG. 4 shows another embodiment of the present invention, 1
A port 72 for a pipeline that sends ink to each valve chamber 71;
Nozzle port 73 and ink tank port 7
4, both ports 72, 74 are provided with respective dedicated solenoids 75, 76, and valve bodies 79, 8 are pressed in the closing direction by springs 77, 78.
0 belongs to it. In particular, the diaphragm 81 of the valve body 79 is designed to have a wider pressure-receiving surface when the valve body is opened than when it is closed.
It is larger than 2. When a solenoid valve having such a configuration is used in place of the solenoid valve 30 in FIG. 2, only the solenoid 75 is momentarily excited by the solenoid excitation means when recording starts, and only the solenoid 76 is momentarily excited when recording is stopped. do.
In addition, based on the same principle, the solenoid valve 30 does not share the solenoid 31, and the plungers 41, 4
It is also possible to provide dedicated solenoids for each of 1' so that they can be excited independently.

As is clear from the above explanation, the present invention uses a pressure switching solenoid valve that is instantaneously energized only when recording starts and stops, and during which time the pressure switching solenoid valve is self-maintained in the open state using pressurized ink, thereby reducing consumption. With electric power, it is possible to eject ink with a good start-up and to cut off the ink with a good sharpness.

[Brief explanation of drawings]

FIG. 1 shows a conventional ink jet recording device equipped with a solenoid-type ink pressure adjustment device, FIG. 2 shows an ink jet recording device according to the present invention, and FIG. 3 shows the pressure according to the present invention used in the device shown in FIG. The detailed structure of the switching solenoid valve and FIG. 4 show another embodiment of the present invention. 12: Ink tank, 17: Pressure sensor, 2
0: Accumulator, 25: Nozzle, 32,3
3, 71: Valve chamber, 31, 51, 75, 76: Solenoid, 44, 44', 65, 81, 82: Diaphragm, 45, 45', 60, 79, 80: Valve body.

Claims (1)

[Scope of Claims] 1. In an ink jet recording device configured to pressurize ink stored in an ink tank with a pump and jet it from a nozzle, the ink at a set pressure is sent to an ink delivery pipe. In addition to controlling the pump, a pressure switching solenoid valve is provided between the pump and the nozzle, and this solenoid valve is configured to control the pressure switching between the delivery pipe port, the nozzle port, and the delivery pipe port by means of a spring. a valve body that is biased to close the port and driven open by an energized solenoid;
Further, a valve chamber is provided which can be communicated with the ink tank by another valve body independent of this valve body, and the pressure receiving surface of the valve body that opens and closes the port for the delivery pipe is subjected to a spring force once opened under the set pressure. The solenoid is formed to be sufficiently wider than the effective area when closed to the extent that the solenoid can maintain the open state against the Ink jet recording device.