JPH10151763A - Method and apparatus for cleaning ink jet recording head, and ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove inclusions in an ink channel better as compared with prior art. SOLUTION: At the time of purging, all piezoelectric elements 39 are operated through a control section 61 to jet some quantity of ink from a recording head 23 and inclusions e.g. bubbles and dusts, in a manifold 35 and a pressure channel 37 are sucked to the nozzle side. When a compressor 59 is operated subsequently through the control section 61, ink is pressure fed into the manifold 35 and jetted from a nozzle 43 through an ink channel 41. Inclusions, e.g. bubbles and dusts are discharged through the nozzle 43 together with the ink at that time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying an ink jet recording head, a purifying apparatus for purifying an ink jet recording head by the purifying method, and an ink jet printer provided with the purifying apparatus.

[0002]

2. Description of the Related Art An ink jet printer is generally provided with a purifying device (purge device) for a recording head. This purifying device is a device provided for removing inclusions such as air bubbles and dust accumulated in an ink flow path inside a recording head. As one of such purifying devices, conventionally, a purifying device inside a recording head has been used. By supplying ink into the ink flow path at a higher pressure than usual, a process of forcibly discharging inclusions such as air bubbles and dust existing in the ink flow path from the nozzles together with the ink (hereinafter, also referred to as a purge process) ).

[0003]

However, in the above-described conventional purifying apparatus, even if the purging process is performed a plurality of times, the inclusions in the ink flow path may not be sufficiently removed. This is because the size of the cross-sectional area of the ink flow path, the bent state, and the like are not uniform over the entire ink flow path. In some cases, the flow velocity of the ink may not be sufficiently high, and it is assumed that when inclusions stay in such places, the inclusions cannot be removed.

Here, in order to remove such inclusions, for example, the pressure of the ink supplied by the purifying device is set to be sufficiently high so that a sufficient flow velocity is generated even in a place where the flow velocity of the ink is hardly increased. However, in order to realize such a purification method, for example, a pressure-resistant component is used in each part constituting the ink flow path, or a bonding strength between the components is increased. Over the entire ink flow path to the printhead nozzles,
Since a strong structure that can sufficiently withstand high pressure has to be adopted, it is not a practical measure in consideration of problems such as productivity and cost.

[0005] Under such circumstances, in the conventional ink jet printer, even though the purging process is performed by the purifying device, the printing operation may be shifted to the actual printing operation without sufficiently removing the inclusions. During operation, non-ejection of the ink is caused, or the speed of the ejected ink is decreased due to a decrease in the ejection pressure of the ink. Had caused the problem of inviting.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a method of purifying an ink jet recording head capable of removing inclusions in an ink flow path better than before, and a method thereof. An object of the present invention is to provide a purifying device for purifying an ink jet recording head by a purifying method, and an ink jet printer provided with the purifying device.

[0007]

Means for Solving the Problems and Effects of the Invention In order to achieve the above-mentioned object, the invention according to claim 1 provides an ink-jet recording head having an ink passage formed in an ink flow path.
By supplying ink at a higher pressure than usual, an ink jet recording head purifying method in which inclusions such as bubbles and dust present in the ink flow path are forcibly discharged from the nozzles together with the ink, A piezoelectric element provided in the recording head as a pressure generating source for ejecting ink is operated before supplying the ink at the high pressure and / or during supplying the ink at the high pressure.

[0008] In this cleaning method, in order to discharge the inclusions in the ink flow path, before the ink is supplied at a higher pressure than normal and / or during the supply of the ink at a higher pressure than usual, the recording head is provided with the ink. Activating the disposed piezoelectric element. Here, inclusions that can be removed only by supplying ink at a higher pressure than usual are removed without any problem as in the related art.

On the other hand, among the inclusions that cannot be removed by simply supplying ink at a higher pressure than usual, those that can move with the operation of the piezoelectric element include the inclusions that are associated with the operation of the piezoelectric element. To the opening side of the nozzle.
Such inclusions are usually drawn to the nozzle side only by the operation of the piezoelectric element, but are not ejected from the nozzles, thereby causing ink ejection failure or the like. After or at the same time as the ink is moved to the nozzle side, the ink is supplied at a higher pressure than usual, so this inclusion is also discharged to the outside from the opening of the nozzle.

In particular, when the piezoelectric element provided in the recording head is operated while the ink is supplied at a higher pressure than usual, the ink ejection amount increases by the amount of ink ejected by the piezoelectric element. As a result, the pressure in the ink flow path in the vicinity of the nozzle decreases, so that the pressure difference from the ink supply source side increases, the flow velocity of the ink in the ink flow path increases, and the inclusions are more likely to be swept away. State
There is also an effect that the discharge of inclusions is promoted.

Among the inclusions that cannot be removed simply by supplying ink at a higher pressure than usual, those that are not moved even when the piezoelectric element is actuated cause ink ejection failure or the like in the first place. Since it does not cause any inconvenience, even if it cannot be removed, it does not usually cause a problem.

In this way, not only inclusions that can be removed by simply supplying ink at a higher pressure than normal, but also inclusions that cannot be removed by simply supplying ink at a higher pressure than normal, are forced together with the ink. Therefore, inclusions that may adversely affect the print quality are discharged better than before.

Incidentally, the timing for operating the piezoelectric element may be either before supplying ink at a higher pressure than usual or during supplying ink at a higher pressure than usual. Will be higher. However, if both are used, the wasteful amount of discharged ink is correspondingly large. Therefore, either one of them may be used in consideration of the balance with the economical aspect. In this case, if there are relatively many inclusions in the vicinity of the piezoelectric element due to the shape of the ink flow path or the like, the piezoelectric element is operated before supplying ink at a higher pressure than usual. If there are many inclusions at positions away from the target piezoelectric element, it is preferable to operate the piezoelectric element while supplying ink at a higher pressure than usual.

Next, in purifying the ink jet recording head by the purifying method described above, the purifying apparatus according to the second aspect, that is, in the ink flow path formed in the ink jet recording head, the pressure is higher than usual. By supplying ink at, in the ink jet recording head purifying apparatus equipped with ink forced discharge means for forcibly discharging from the nozzles the inclusions such as air bubbles and dust present in the ink flow path, A piezoelectric element disposed in the recording head as a pressure generating source for ink ejection at the time of a recording operation is supplied to the piezoelectric element before the ink forcible discharge unit supplies the ink at the high pressure and / or supplies the ink at the high pressure. Using an ink-jet recording head purifying device, comprising a piezoelectric element driving means to be operated in the meantime. And good.

In such a purifying apparatus, the ink forcible discharging means discharges the inclusions in the ink flow path.
Before supplying ink at a pressure higher than normal and / or during supplying ink at a pressure higher than normal, the piezoelectric element driving means may include:
Since the piezoelectric element arranged in the recording head is operated, even if the ink is forcibly ejected at a position where the ink remains at a position where the ink remains at a high pressure only by supplying ink at a high pressure,
As described above, the ink is forcibly discharged together with the ink.

By the way, the number of the piezoelectric elements in the recording head is usually arranged by the number corresponding to the number of the nozzles.
If the position where the inclusions easily stay is limited to the vicinity of the specific piezoelectric element, the piezoelectric element driving unit may drive only the necessary piezoelectric elements according to the position where the inclusions easily stay, 4. The piezoelectric element driving means according to claim 3, wherein when it is difficult to specify a position where the inclusion easily stays, or when the inclusion easily stays at a position distant from the piezoelectric element, the piezoelectric element driving unit may be configured to control the recording head. It is preferable to operate all of the plurality of piezoelectric elements disposed therein.

According to such a purifying device, the inclusions are easily moved to the nozzle side in the vicinity of all the piezoelectric elements, and the ink in the vicinity of the nozzle is smaller than when only some of the piezoelectric elements are operated. Since the pressure drop in the flow passage becomes remarkable, the pressure difference from the supply source of the pressurized ink becomes larger, and accordingly, the flow velocity of the ink in the ink flow passage increases, and the inclusions that have stayed Is easily discharged.

As is apparent from the above description, according to the above-described apparatus for purifying an ink jet recording head, it is possible to more effectively remove the inclusions present in the ink flow path inside the recording head than in the prior art. . Therefore, the ink jet printer according to the fourth aspect is less likely to cause problems such as non-ejection of ink or a decrease in the speed of ejected ink, and can perform higher quality recording than the conventional ink jet printer. .

[0019]

Next, embodiments of the present invention will be described with reference to the drawings. As schematically shown in FIG. 1, an ink jet printer exemplified as an embodiment includes a platen 7 rotatably supported on a frame 3 via a shaft 5, and includes a platen 7 and another roller (not shown). The recording paper P can be conveyed at a predetermined paper feed pitch by sandwiching the recording paper P therebetween and driving the platen 7 to rotate by the platen motor 9.

Further, two guide rods 11 are arranged in parallel with the platen 7, and a carriage 13 slidable along the guide rods 11 is attached to the guide rods 11. The carriage 13 has a pair of pulleys 15, 1
When the pulley 17 is rotationally driven by the carriage motor 21 in both forward and reverse directions, the timing belt 19 is reciprocated along the guide rod 11. On the carriage 13, a head unit 25 having an ink jet type recording head 23 arranged to face the recording paper P is mounted.

As shown in FIG. 2A, a lower end 35a is provided on the left and right sides of the recording head 23, as shown in FIG.
The two manifolds 35 through which ink flows from the upper end 35b to the upper end 35b are formed in parallel, and from each manifold 35, 34 pressure channels 37 each extend inward. As shown in FIG. 2B, each pressure flow path 37 has an inner wall on the upper surface side of the drawing formed by a piezoelectric element 39. When a driving voltage is applied to the electrodes of the piezoelectric element 39, the pressure flow The volume of the passage 37 changes, and the ink introduced therein is pressurized. FIG.
4B, the nozzle 4 having an opening on the surface opposite to the pressure flow channel 37 via the ink flow channel 41 extending downward.
3 are communicated, and the pressurized ink is ejected from the nozzle 43 to the outside (in the direction of the arrow in FIG. 2B).

As shown in the schematic diagram of FIG. 3, a first ink tank 47 serving as an ink supply source communicates with each manifold 35 via an ink supply path 45, and also via an ink discharge path 49. The first ink tank 47 and the second ink tank 51 communicate with each other through a communication path 53.
The communication path 53 is provided with a one-way valve 55 that allows ink to pass only from the second ink tank 51 to the first ink tank 47 side. A compressor 59 is connected to the first ink tank 47 via a supply / exhaust pipe 57 so that high-pressure air supplied from the compressor 59 can be introduced into the first ink tank 47.

Further, the operation states of the piezoelectric element 39 and the compressor 59 are both controlled by the control section 61. The control section 61 is a well-known logic operation circuit mainly composed of a CPU and the like, and controls the operation of each section according to a predetermined control program. Incidentally, by controlling the operation of the compressor 59 by the control unit 61, the control unit 61 functions as an ink forcible discharge unit in the purification device of the present invention, and the control unit 61 also functions as a piezoelectric element driving unit in the purification device of the present invention. I do. The platen motor 9 and the carriage motor 21 shown in FIG. 1 are also controlled by the control unit 61.

Next, a purge process in the ink jet printer will be described with reference to a flowchart of FIG. This purge process is automatically executed when the power is turned on or left for a long time. When the purge process is started, first, the control unit 61 controls the carriage motor 21 to move the carriage 13 to a predetermined position. It is moved to the purge position (S110). The purge position is a position where the surface of the recording head 23 on the nozzle opening side faces an ink absorbing material (not shown) such as wipe paper, and is usually outside the recordable range in which the recording head 23 faces the recording paper P. Is set to Therefore, if the carriage 13 is moved to this purge position, even if ink is ejected from the recording head 23, the ink does not stain the recording paper P, and all the ejected ink is absorbed by the ink absorbing material. Will be.

Subsequently, the control unit 61 controls all the piezoelectric elements 3
9 is operated (S120). As a result, a certain amount of ink is ejected from the recording head 23, and at the same time, if there are any inclusions such as bubbles and dust inside the manifold 35, the pressure channel 37, etc., the inclusions are sucked toward the nozzle 43. Is done. However, at this point, if a large bubble is present, for example, it is difficult to completely push out the bubble from the nozzle 43 because the pressure wave generated by the piezoelectric element 39 is absorbed by the bubble. Have difficulty.

Then, the control section 61 subsequently operates the compressor 59 (S130). As a result, the pressure in the first ink tank 47 increases, and ink is pressure-fed into the manifold 35 via the ink supply path 45. Further, the ink in the manifold 35 passes through the pressure flow path 37 and the ink flow path 41. After that, it is extruded from the nozzle 43. At this time, S
If there are inclusions such as bubbles and dust guided to the inside of the pressure channel 37, the ink channel 41, and the like by the process of 120, the inclusions are discharged from the nozzle 43 together with the ink. The ink in the manifold 35 is also discharged to the second ink tank 51 via the ink discharge path 49.
At this time, if there are inclusions such as bubbles and dust inside the manifold 35, the inclusions are discharged to the second ink tank 51 together with the ink. In particular, since the compressor 59 is also operated after executing the processing of S120, the nozzle 4
3, the amount of ink flowing into the manifold 35 also increases, and as a result,
Since the flow rate of the ink in the manifold 35 increases,
Inclusions are easily swept toward the ink discharge path 49 side.

By the way, the flow velocity of the liquid flowing in the pipe is
Generally, there is a tendency that the middle part of the pipeline cross section is faster and the peripheral part is slower. Therefore, even in the manifold 35, it is easy for the inclusions to stay in the peripheral part, but on the side where the pressure passage 37 is formed, Since the inclusions flow into the pressure flow path 37, the inclusions are likely to substantially stay there because of the peripheral portion of the manifold 35 on the side where the pressure flow path 37 is not formed (FIG. 2A). In other words, near the left end of the left manifold 35 and near the right end of the right manifold 35). However, in the present ink jet printer, the flow rate of the ink in the manifold 35 is increased as described above, so that the inclusions do not stay at the above-described locations.

After a predetermined time has elapsed after the execution of the processing of S130, the control section 61 subsequently stops the operated piezoelectric element 39 (S140). Then, after a predetermined time has elapsed, the compressor 59 is also stopped (S15).
0). Here, the reason why the piezoelectric element 39 is stopped first is to ensure that the inclusions collected toward the nozzle 43 due to the operation of the piezoelectric element 39 are more reliably discharged by the ink pumped from the compressor 59. , After sufficiently operating the piezoelectric element 39 and the compressor 59,
Both may be stopped almost simultaneously.

By the above-described purging process, in this ink jet printer, the piezoelectric element 39 is operated before the ink is supplied at a high pressure by operating the compressor 59 and during the supply of the ink at a high pressure. In addition, it is possible to remove inclusions in the ink flow path better than before.

Although the embodiment of the present invention has been described above, various constitutional means of the present invention can be considered in addition to the above embodiment. For example, in the above-described embodiment, the piezoelectric element 39 is operated before the ink is supplied at a high pressure by operating the compressor 59 and during the period between the supply of the ink at a high pressure. Actuating the piezoelectric element 39 has a corresponding effect.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a schematic configuration of an ink jet printer.

FIG. 2 shows the shape of an ink flow path inside a print head,
2A is a front view as viewed from the back side of the nozzle opening, and FIG. 2B is a cross-sectional view of a cut surface indicated by line AA in FIG.

FIG. 3 is a schematic diagram showing the entire ink flow path and a control system of a piezoelectric element and a compressor.

FIG. 4 is a flowchart of a purge process.

[Explanation of symbols]

3 ... frame, 5 ... shaft, 7 ... platen, 9
... Platen motor, 11 ... Guide rod, 13
... Carriage, 15, 17 ... Pulley, 19 ...
・ Timing belt, 21 ・ ・ ・ Carriage motor, 2
3 print head, 25 head unit, 35
... Manifold, 37 ... Pressure flow path, 39 ...
Piezoelectric element, 41: ink flow path, 43: nozzle,
45: ink supply path, 47: first ink tank, 4
9: ink discharge path, 51: second ink tank, 53
... communication path, 55 ... one-way valve, 57 ... supply / exhaust pipe, 59 ... compressor, 61 ... control part.

Claims (4)

[Claims] 1. An ink supply system comprising: an ink supply unit configured to supply ink at a higher pressure than usual to an ink flow path formed in an ink jet type recording head, thereby removing inclusions such as bubbles and dust existing in the ink flow path together with the ink; In a method of purifying an ink jet recording head forcibly discharging from a piezoelectric element, a piezoelectric element disposed in the recording head as a pressure generating source for ink ejection during a recording operation is supplied before the ink is supplied at the high pressure and And / or operating while supplying ink at the high pressure. 2. A method according to claim 1, wherein the ink is supplied to the ink flow path formed in the ink jet type recording head at a higher pressure than usual, so that inclusions such as bubbles and dust existing in the ink flow path are formed together with the ink. An ink-jet recording head purifying device provided with an ink forcible discharging means for forcibly discharging ink from the ink, wherein a piezoelectric element disposed in the recording head as a pressure generating source for ink ejection during a recording operation is provided by the ink. Before the forcible discharge means supplies ink at the high pressure and / or
Alternatively, there is provided a purifying apparatus for an ink jet type recording head, comprising: a piezoelectric element driving unit which operates while supplying the ink at the high pressure. 3. The apparatus for purifying an ink jet recording head according to claim 2, wherein said piezoelectric element driving means activates all of a plurality of piezoelectric elements provided in said recording head. Purification device for inkjet recording head. 4. An ink jet printer comprising the purifying device for an ink jet recording head according to claim 2.