JPH05338161A - Ink jet recording head - Google Patents

Abstract

PURPOSE:To prevent printing failure based on prediction, by predicting the inability of each nozzle of an ink jet recording head to jet ink. CONSTITUTION:In the upper part of the upper drawing, the meniscus of a hemispherical ink 10 in a nozzle 12 is shown. In the lower drawing, a broken line 1 indicates the first movement of the meniscus of the ink after being jetted, that is, the movement of the meniscus of the ink stopping near the opening of the nozzle, a dash-and-dot line 2 indicates the second movement, that is, the movement of the meniscus of the ink which does not return after moving away from the opening of the nozzle towards the inside, and a solid line 3 indicates the third movement, that is, the movement of that which returns after moving back from the opening of the nozzle towards the inside. In the cases of the first and second movements the subsequent ink jetting cannot happen, and in the case of the third movement the subsequent ink jetting can happen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head which has a function of predicting ejection failure of each nozzle and can prevent printing defects based on the prediction.

[0002]

2. Description of the Related Art Conventionally, a method of ejecting ink from fine nozzle holes and adhering it onto a recording medium such as paper for recording is known as an ink jet recording method. And as one of the principles, there is an on-demand type ink jet recording head. This type of ink jet recording head is generally etched on glass, a metal plate, etc. as shown in FIG. 6 which is a plan view seen from the groove side of the cavity plate and FIG. 7 which is a sectional view of a conventional example. A plurality of ink ejection nozzles 12, ejection passages 13, ink pressurizing chambers 15, ink supply passages 16, filter passages 18, and a cavity plate 11 in which a common ink reservoir 17 is formed by mechanical machining or the like;
After stacking and integrating 19 and 19, a piezoelectric element 20 as an electromechanical conversion element is bonded to a position facing the ink pressurizing chamber 15 on the outer surface of the vibration plate 19 via a conductive film 21. ing.

In such a structure, when a voltage as an electric signal is applied to the piezoelectric element 20, the vibrating plate 19 is displaced inside the ink pressurizing chamber 15 to rapidly reduce the volume of the ink pressurizing chamber 15. Ink corresponding to the volume is ejected from the nozzle 12, which becomes an ink droplet and is spotted and printed on the facing recording paper.

[0004]

Generally, in an ink jet recording head, the diameter of each nozzle portion is extremely small,
In addition, since there is a constant risk of dust and air bubbles being mixed in, there is a high possibility that ink ejection will become impossible. Since the impossibility of ink ejection is the largest defect element that impairs the printing quality, it is very desirable to maintain and improve the printing quality if the ejection failure of each nozzle can be predicted.

An object of the present invention is to solve the above-mentioned problems of the prior art and to have a function of predicting the ejection failure of each nozzle, and based on the prediction, an ink jet recording head capable of preventing printing defects in advance. To provide.

[0006]

An ink jet recording head according to a first aspect of the invention has three possible movements of an ink meniscus after ink is ejected from a nozzle portion, which remains near the first nozzle opening portion. A sensor for detecting a movement, a movement that does not return while retracting inward from the second nozzle opening, and a movement that retracts inward from the third nozzle opening and then returns again; The next ink ejection is predicted to be impossible based on the detection of the first and second movements, and the next ink ejection is predicted to be possible based on the detection of the third movement.

An ink jet recording head according to a second aspect is the recording head according to the first aspect, wherein the sensor is
It is a heating type resistance element which is embedded in the inner surface of the peripheral wall of the nozzle portion so as to extend in the longitudinal direction so as not to obstruct the ink flow. An ink jet recording head according to a third aspect of the present invention is the recording head according to the first aspect, wherein the sensor is embedded in the peripheral wall on one side perpendicular to the longitudinal direction of the nozzle portion so as not to obstruct the ink flow. And a light receiving section that is embedded in the peripheral wall on the same side and receives the light emitted from the light emitting section and reflected by the inner surface of the peripheral wall of the nozzle section on the other side.

[0008]

In the ink jet recording head according to any one of claims 1 to 3, for example, the heat generating resistance element as in claim 2 or each sensor which is the reflection type optical sensor as in claim 3 allows the nozzle section to be operated. When the first movement of the ink meniscus remaining after the ink ejection of the ink remains near the nozzle opening or the second movement of the ink meniscus receding inward from the nozzle opening and not returning is detected. , The next ink ejection is predicted to be impossible, and when the third movement in which the ink meniscus retreats from the nozzle opening toward the inside and then returns to the vicinity is detected, the next ink ejection is Predicted to be possible.

[0009]

Embodiments of the ink jet recording head according to the present invention will be described below with reference to the drawings. The embodiment is basically the same as the conventional example, except that a sensor for detecting the movement of the ink meniscus after ink ejection is attached to the nozzle. FIG. 1 is a schematic diagram showing three modes of movement of an ink meniscus after ink ejection. A partial enlarged view of the distance X from the nozzle opening of the nozzle portion as a starting point is shown on the upper side, and the movement of the ink meniscus after ink ejection is shown on the lower side along the horizontal axis of the distance X from the nozzle opening toward the inside. It is shown by the vertical axis of the time T starting from the injection, and the directions of the distance X between the upper side and the lower side are made to correspond in common.

On the upper side of FIG. 1, the nozzle 12 is formed such that the groove of the cavity plate 11 is covered by the diaphragm 19.
The meniscus of the hemispherical ink 10 in the nozzle 12 is shown on the left side. In the lower part of FIG.
The first movement of the ink meniscus after ink ejection, that is, the movement that remains near the nozzle opening is shown. Also, the one-dot chain line display similarly shows the second movement thereof, that is, the movement that does not return while retracting inward from the nozzle opening. Further, the solid line indicates the third movement, that is, the movement of retreating from the nozzle opening toward the inside and then returning again. As described above, the movement of the ink meniscus after ink ejection can take three forms, and when the first and second movements of ,, and 2 occur, the next ink ejection cannot be performed, and the third movement of It has been empirically confirmed that the next ink ejection is possible when the movement of the ink occurs. In the embodiment, based on this principle, the movement of the ink meniscus after ink ejection is detected by a sensor, and the next ink ejection is predicted as being impossible or possible. It has been experienced that when each of the first and second movements of (1) and (2) occurs, there is a high probability that not only the next ink ejection but also the ink ejection at that time will be impossible.

Two types of sensors for detecting the movement of the ink meniscus after ink ejection will be described with reference to FIGS. 2 and 3. FIG. 2 is a side view of one sensor attached to the nozzle portion in the embodiment. This one sensor is a heat-generating resistance element 1 and is embedded in the inner surface of the diaphragm 19 which is the upper wall of the nozzle so as to extend in the longitudinal direction so as not to hinder the ink flow, and is drawn out to the left and right ends. Lead wires are connected.
Since the temperature of the resistance element portion not soaked in the ink 10 rises, its resistance value is large, and conversely, the temperature of the resistance element portion soaked in the ink 10 is low, so its resistance value is small. Therefore, as the ink meniscus recedes inward from the nozzle opening, the total resistance value of the heat-generating resistance element 1 increases. FIG. 3 is a schematic diagram of the output form of one sensor,
The horizontal axis represents the total resistance value R of the heat-generating resistance element 1, and the vertical axis represents the time T starting from ink ejection. In FIG. 3, the change in the total resistance value R of the heat-generating resistance element 1 with respect to time T is shown as, ..., Corresponding to each movement of the ink meniscus on the lower side of FIG. Therefore, based on the pattern of the change of the resistance value R with respect to the time T, it is possible to predict whether the next ink ejection will be possible or impossible.

FIG. 4 is a side view of another sensor attached to the nozzle portion in the embodiment. The other sensor is a reflection type optical sensor 2 which is embedded in the bottom wall of the groove of the cavity plate 11 as a nozzle so as not to hinder the ink flow.
And a light receiving section 4 which is embedded adjacent to this. When there is no ink 10 on the upper part of the set of the light emitting unit 3 and the light receiving unit 4, the light emitted from the light emitting unit 3 is reflected by the inner surface of the wall on the opposite side and then enters the light receiving unit 4. On the contrary, the light emitting part
3, When the ink 10 is on the upper part of the set of the light receiving section 4, the light emitted from the light emitting section 3 does not enter the light receiving section 4. FIG. 5 is a schematic diagram of the output form of another sensor, in which the horizontal axis indicates whether light is received by the light receiving unit 4 (ON) or not (OFF), and the vertical axis indicates the time T starting from ink ejection. In FIG.
A change in ON / OFF of the light reception in the light receiving unit 4 with respect to the time T is shown as, ..., Corresponding to each movement of the ink meniscus on the lower side of FIG. Therefore, it is possible to predict whether or not the next ink ejection will be possible or impossible based on the pattern of the change in the ON / OFF of the light reception at the light receiving unit 4 with respect to the time T.

[0013]

In the ink jet recording head according to any one of claims 1 to 3, the nozzle is formed by the heat-generating resistance element as claimed in claim 2 or the reflection type photosensor as claimed in claim 3. The first movement of the ink meniscus remaining after the ink ejection at the nozzle part remains near the nozzle opening, or the second movement of the ink meniscus receding inward from the nozzle opening and not returning is detected. When it is detected that the next ink ejection is impossible, and when a third movement is detected in which the ink meniscus recedes from the nozzle opening toward the inside and then returns to the vicinity, the next ink is detected. Injection is predicted to be possible. Therefore, it has a function of predicting the ejection failure of each nozzle, it is possible to stop the printing operation based on the prediction, prevent printing defects in advance, and accurately perform the function restoration of the nozzle that is predicted to be ejection failure. it can.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing three modes of movement of an ink meniscus after ink ejection.

FIG. 2 is a side view of one sensor attached to the nozzle unit in the embodiment.

FIG. 3 is a schematic diagram of the output form of one sensor.

FIG. 4 is a side view of another sensor attached to the nozzle unit in the embodiment.

FIG. 5 is a schematic diagram of an output form of another sensor.

FIG. 6 is a plan view of a common cavity plate of the example and the conventional example.

FIG. 7 is a sectional view common to the embodiment and the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat generation type resistance element 2 Reflection type optical sensor 3 Light emitting part 4 Light emitting part 10 Ink 11 Cavity plate 12 Nozzle 19 Vibration plate

Claims (3)

[Claims] Claims: 1. Three possible movements of an ink meniscus after ink ejection in a nozzle portion, that is, movement that remains near the first nozzle opening portion and retreat from the second nozzle opening portion toward the inside. A sensor that detects a motion that does not return and a motion that returns from the third nozzle opening toward the inside and then returns again is provided, and the next ink is detected based on the detection of each of the first and second motions. An inkjet recording head characterized in that it is predicted that ejection is impossible, and that it is predicted that next ink ejection is possible based on the detection of the third movement. 2. The recording head according to claim 1, wherein the sensor is a heating type resistance element embedded in the inner surface of the peripheral wall of the nozzle portion so as to extend in the longitudinal direction so as not to obstruct the ink flow. Inkjet recording head. 3. The recording head according to claim 1, wherein the sensor is provided on the same side as the light emitting portion embedded in the peripheral wall on one side perpendicular to the longitudinal direction of the nozzle portion so as not to obstruct the ink flow. An ink jet recording head comprising: a reflection type optical sensor having a light receiving portion which is embedded in a peripheral wall and which receives light emitted from the light emitting portion and emitted from the inner surface of the peripheral wall of the nozzle portion on the other side.