JPH1199646A - Ink jet recording head and ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording head having a function for self- diagnosing the trouble, and an ink jet recorder having high operational efficiency and reliability. SOLUTION: A driving circuit for the piezoelectric element 16 in an ink jet recording head is provided with a charge amplifier 84. Time variation of charge supply is measured at the time of driving the piezoelectric element 16 and the pressure waveform of an ink pressure chamber 15 is grasped with reference to the charge quantity waveform when no ink is present in an ink channel thus detecting a situation where a bubble is present in the ink channel and a situation where the fluid resistance has increased due to presence of dust. The recorder detects a trouble in the recording head at nonprinting timing and drives a trouble eliminating means based on the detection results thus enhancing the reliability.

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 technique in which ink is ejected as small droplets from nozzles and is recorded on a recording medium.

[0002]

2. Description of the Related Art The ink jet recording technique is one of the most frequently used printing methods at present because it can perform high-speed printing, has a high printing resolution, and can easily cope with colorization. FIG. 4 is a partial cross-sectional perspective view showing the structure of an example of such an ink jet recording apparatus (hereinafter simply referred to as a recording apparatus). The configuration shown in FIG. 4 is generally called a serial printing system. Inkjet recording head (hereinafter abbreviated as recording head)
Is mounted on the carriage 2
Thus, the recording paper 3 as a print medium is fed in a direction perpendicular to the transport direction, and printing is performed line by line by ink droplets ejected from nozzles of the recording head during that time.

FIG. 5 is a diagram showing a relationship between an example of the arrangement of nozzles of a recording head and its printing dots. In this example,
The nozzles are arranged in a zigzag pattern, the vertical spacing between adjacent nozzles is 1/150 inch, and the horizontal spacing is 9/3.
00 inches. The ink is discharged perpendicularly to the surface of the recording paper 3 from nozzles of the recording head on the lower surface of the carriage in FIG. 4 to form print dots. Accordingly, one line is printed by the carriage 2 being guided and scanned by the spacing shaft 45, and characters and images are printed in combination with the line feed that is subsequently performed.

FIG. 6 is a sectional view showing the structure of an example of a recording head, FIG. 7 is a view for explaining the operation of the recording head, FIG. 6A is a sectional view showing a standby state, and FIG. FIG. 3C is a cross-sectional view when applying an ink, and FIG. The recording head 1 shown in FIG. 6 is a recording head of a printing method called a Kaiser type. The groove formed in the substrate 11 and the vibration plate 12 form an ink supply unit 13, an ink pressurizing chamber 14, and a nozzle 15. Are formed, and a piezoelectric element 16 is bonded to the outer surface of the vibration plate 12 corresponding to the ink pressurizing chamber 14.

The substrate 11 is formed by, for example, using a silicon wafer as a raw material and etching the grooves by a plasma etching method or the like. The grooved substrate 11 and the vibration plate 12 made of a glass plate are joined by an electrostatic joining method or the like to form an ink flow path. Vibration plate to which piezoelectric element 16 is bonded
The surface of 12 is preliminarily prepared by vacuum evaporation or sputtering.
A common electrode of TO or gold is formed, and a flexible printed board (hereinafter abbreviated as FPC) is attached to the upper electrode of the bonded piezoelectric element 16 by a method such as soldering.
(The common electrode and the FPC are shown in FIGS. 6 and 7).
Not shown). When a voltage is applied between the common electrode and the FPC, the piezoelectric element 16 is deformed. When a voltage in a direction in which the length direction of the piezoelectric element 16 is shortened is applied, the diaphragm 12 is deformed toward the ink pressurizing chamber 14 due to a bimorph effect between the diaphragm 12 and the piezoelectric element 16, and the volume of the ink pressurizing chamber 14 is reduced. Decrease.

Next, the principle of ink droplet ejection will be described with reference to FIG. FIG. 7A shows a standby state of the recording head 1, and a voltage is applied to the piezoelectric element 16. The piezoelectric element 16 contracts in the d ₃₁ direction by the reverse piezoelectric effect,
The vibration plate 12 is deformed so that the volume of the ink pressurizing chamber 14 is reduced. When printing, the applied voltage is returned to zero, and the diaphragm 12 is returned to a flat state as shown in FIG.
The inside of the ink pressurizing chamber 14 is set to a negative pressure. At this time, the ink supply unit
The ink 9 is supplied from 13 to the ink pressurizing chamber 14. Subsequently, when a voltage is again applied to the piezoelectric element 16 to return to the state shown in FIG. 7C, a positive pressure is generated in the ink pressurizing chamber 14, and the ink 9 is ejected from the nozzle 15 and the ink droplet is ejected. At 91, it flies toward the recording paper 3 as a recording medium and adheres as ink dots on the recording paper 3.

FIG. 8 is a circuit diagram showing the principle of the driving circuit of the piezoelectric element 16. When applying a voltage to the piezoelectric element 16,
A voltage signal for turning on the first transistor 81 and turning off the second transistor 82 is input to each base. In this state, the power supply voltage is applied to the piezoelectric element 16 through the resistor 83, and the piezoelectric element 16 is charged. When the voltage applied to the piezoelectric element 16 is set to zero, a voltage signal for turning off the first transistor 81 and turning on the second transistor 82 is input to each base. In this state, the piezoelectric element 16 is in a discharged state.

FIG. 9 shows a voltage waveform applied to the piezoelectric element 16. The initial state in which the first transistor 81 is in the ON state corresponds to the standby state shown in FIG. 7B, the ink is supplied from the ink supply unit 13, and the voltage suddenly increases, the piezoelectric element 16 contracts again, and the internal pressure of the ink pressurizing chamber 14 increases.
FIG. 7C shows a state in which the ink droplet 91 is ejected. When this state is stabilized, the state becomes the initial state shown in FIG.

As an inkjet recording system other than the Kaiser type described above, there is a system called a bubble jet system. This method is a method in which an ink droplet is ejected from a nozzle by a sudden increase in pressure when the ink is heated and vaporized, and has a feature that a recording head can be miniaturized. In the above two ink jet recording methods, ink droplets are ejected from nozzles using the pressure generated in the ink pressurizing chamber. The main causes of printing failure in these types of recording apparatuses are bubbles and dust existing in the ink flow path. Bubbles absorb changes in pressure by volume changes and hinder the pressure rise required to eject ink droplets.Dust increases fluid resistance in the ink flow path and transmits the necessary pressure to the nozzle. Or hinder the supply of ink.

Generally, a pump 63 (see FIG. 4) is used to remove air bubbles and dust that cause such a printing failure.
A trouble cause removing means (trouble solving means) using a negative pressure generating mechanism such as the above is provided, and the ink 9 in the ink flow path is forcibly sucked from the nozzle 15 of the recording head 1 by the negative pressure.
Bubbles and dust in the ink flow path are removed by the flow of the ink.

In addition, printing defects may also occur due to accumulation of ink or foreign matter adhering on the nozzle surface of the recording head 1. To remove this defect, a wiper 61 (see FIG. 4) for cleaning the nozzle surface is provided. In FIG. 4, the protection device 6 includes a failure cause removing unit using a negative pressure generating mechanism such as the pump 63 and the wiper 61.

The function and operation of the protection device 6 will be described in more detail with reference to FIG. The protection device 6 includes a pump driving unit 64 in addition to the wiper 61, the cap 62, and the pump 63 shown in FIG. The cap 62 has a function of preventing drying of the ink of the nozzles 15 of the recording head 1 in addition to a function of forming an airtight space for generating a negative pressure.
That is, when the power of the recording apparatus is turned off or when printing is not performed, the recording head 1 is located at a position just above the cap 62 called a home position, is covered by the cap 62, and is isolated from the surrounding atmosphere. In addition, an increase in viscosity and adhesion of dust due to drying of the ink are prevented. Therefore, the cap 62 is in the home position,
The recording head 1 is supported by an elevating mechanism (not shown) so as to be able to contact and separate from the nozzle surface.

FIG. 10A shows a state in which the recording head 1 is at the home position and is covered with the cap 62. FIG. 10B shows a state immediately before printing is started.
The state where the cap 62 is lowered and the carriage 2 on which the recording head 1 is mounted can move to the left is shown. In this state, the recording head 1 performs idle discharge of the ink for the purpose of stabilizing the meniscus position of the ink. The ink ejected at this time is received by the cap 62. When printing is completed, the recording head 1 returns to the home position again, and returns to the state shown in FIG.

Normally, the operation of removing a print defect is performed by a maintenance command by a user via a host computer when a print defect occurs, or a periodic maintenance command by a timer inside the printer. FIGS. 10C and 10D show the operation of removing the printing failure. The initial state is the state shown in FIG. 10A. In this state, the pump driving unit 64 is driven to lower the piston of the pump 63, the pressure in the cylinder is reduced, and the pressure in the cap 62 is reduced to a negative pressure. The ink in the ink flow path is sucked into the cap 62 through the nozzle to remove bubbles and dust in the ink flow path. The sucked ink is discharged by the pump 63 via the cap 62. Here, the negative pressure generating mechanism using the pump 63 and the pump driving unit 64 has been described, but another type of negative pressure generating mechanism may be used.

Thereafter, the cap 62 is lowered to the state shown in FIG. In this state, the cap 62 is separated from the recording head 1, but the wiper 61 is at a position where it can contact the nozzle surface of the recording head 1, and the nozzle surface of the recording head 1 is moved by moving the carriage 2.
To remove ink and dust adhering to the nozzle surface.

The maintenance command is issued in the recording apparatus according to the prior art described above when the user finds a print defect and performs an operation of removing the print defect when a trouble occurs in the print head, or This is either the case where the operation of removing the printing defect is periodically performed. For this reason, in the conventional recording apparatus, printing without recognizing the abnormality and re-printing due to a printing failure may occur, and a problem that the recording medium is wasted and an extra printing time is required, and an abnormality may occur. However, there is a problem that a maintenance command is issued periodically and ink is wasted unnecessarily.

[0017]

SUMMARY OF THE INVENTION An object of the present invention is to provide a recording head having a function of self-diagnosing a trouble in the recording head in order to solve the above-mentioned problems, and to provide the recording head. It is an object of the present invention to provide a recording apparatus capable of self-diagnosing a trouble and taking measures for solving the trouble to clearly display and distinguish a normal state and an abnormal state.

[0018]

According to the first aspect of the present invention, at least an ink pressurizing chamber for pressurizing ink, an ink supply passage for supplying ink to the ink pressurizing chamber, and an ink pressurizing chamber. In a recording head having a plurality of ink flow paths including nozzles for discharging pressurized ink, and a piezoelectric element as a means for pressurizing the ink on a side wall of the ink pressurizing chamber, the driving of the piezoelectric element is performed. And means for measuring the amount of electric charge flowing into the electrode of the piezoelectric element, and the pressure of the ink in the ink pressurizing chamber adjacent to the piezoelectric element is measured based on the amount of electric charge.

By associating the temporal change in the pressure of the ink pressurizing chamber with the applied voltage pulse, it is possible to estimate and determine whether or not a change in the situation has occurred in the ink flow path. In the second invention, a trouble occurring in the ink flow path is detected based on the measured pressure of the ink in the ink pressurizing chamber. By associating the time change of the pressure of the ink pressurizing chamber with the applied voltage pulse, it is possible to estimate and determine whether or not a change in the situation occurring in the ink flow path becomes a trouble.

In the third aspect of the present invention, as a problem occurring in the ink flow path, an increase in fluid resistance of the ink flow path due to residual air bubbles or dust in the ink flow path is targeted. Most of the troubles that occur in the recording head are the residual air bubbles in the ink flow path or the increase in the resistance of the ink flow path due to dust, so if both of these can be reliably detected and removed, most of the troubles can be resolved. it can.

According to a fourth aspect of the present invention, in the printing apparatus having the printing head according to the third aspect and the trouble solving means, the detection of the trouble occurring in the ink flow path is performed when the power of the printing apparatus is turned on. This is performed when the recording paper is sent out or when the recording paper is transported. If a trouble is detected at the above time, it is not necessary to use the time for printing for the trouble detection.

According to a fifth aspect of the present invention, when the presence of bubbles in the ink flow path is detected, the trouble elimination means for removing the bubbles is activated, and then the pressure of the ink in the ink pressurizing chamber is measured. Means for re-examining the presence or absence of air bubbles, and displaying the presence of air bubbles when air bubbles are detected again. Inspects the residual air bubbles in the ink flow path as a trouble, and if detected, activates the means for removing it.If the removal means works effectively, the recording device is in a normal state. . If the removal is not possible even when the removing means is operated, it is displayed, so that printing in that state can be avoided.

In the sixth invention, when the increase in the fluid resistance of the ink flow path due to the dust is detected, the trouble elimination means for removing the dust is operated, and then the pressure of the ink in the ink pressurizing chamber is measured. To re-examine the presence or absence of an increase in the fluid resistance of the ink flow path due to dust, and indicate that there is an increase in the fluid resistance of the ink flow path due to dust when re-detecting the increase in the fluid resistance of the ink flow path due to dust. Means.

The increase in the fluid resistance of the ink flow path as a trouble is inspected, and if detected, the means for removing it is operated, so that if the removal means works effectively, the recording apparatus will be in a normal state. ing. If the removal is not possible even when the removing means is operated, it is displayed, so that printing in that state can be avoided.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a preferred embodiment of the present invention, a recording head measures a time change (hereinafter referred to as a charge amount waveform) of an electric charge flowing into a piezoelectric element electrode when the recording head is driven, and determines a reference state ( Time variation of the pressure in the ink pressurization chamber (hereinafter referred to as pressure waveform) by comparing with the charge amount waveform in the state where the ink flow path is filled with air.
Is measured, and the state of the recording head is determined by collating with the pressure waveforms of the normal state and various abnormal states which have been input in advance. The recording device operates the trouble elimination means based on the judgment of the state of the print head to eliminate the trouble, and then judges the state of the print head again and displays the abnormal state if it remains. Let it.

An embodiment will be described below. [Embodiment of Recording Head] FIG. 1 is a circuit diagram showing the construction of an embodiment of a recording head according to the present invention. Piezoelectric element 16
Drive circuit comprises two transistors 81 as in the prior art.
, 82 and a resistor 83 connected to the output side, and the driving of the transistors 81 and 82 is the same as in the prior art, so that the description is omitted. In the present invention, a charge amplifier 84 for measuring the amount of charge flowing into the piezoelectric element 16 is connected to one terminal of the drive circuit. Although only one circuit is shown in FIG. 1, in an actual recording head, usually, a plurality of ink flow paths are provided, and a plurality of piezoelectric elements 16 are provided in correspondence with them.
One charge amplifier 84 is connected to each piezoelectric element 16, and the same number of measurement circuits as the number of piezoelectric elements 16 are provided.

FIG. 2 shows an example of a charge amount waveform when the piezoelectric element 16 is driven. FIG. 2A shows a state where the ink is not filled in the ink flow path (only air), that is, the charge amount in the reference state. FIG. 4B is a diagram illustrating a charge amount waveform of Q ₀ , and FIG. 4B is a diagram illustrating a charge amount waveform of a charge amount Q ₁ in a state where the ink flow path is completely filled with ink. Do not know If you do not strictly comparable, but the fall and rise and is more of Q ₀ becomes steep, shows a fast response. This is because the ink exerts a force on the diaphragm 16 that prevents the diaphragm 12 from moving when ink is present. That is, when the ink is filled, the ink pressurizing chamber 14
This is because a negative pressure is generated when trying to increase the volume, and a positive pressure is generated when trying to reduce the volume.

In general, a strain S and an electric displacement D generated when a stress T and an electric field E are applied to a piezoelectric element include an elastic compliance s ^E , a piezoelectric strain constant d, and a transposed matrix of the piezoelectric strain constant d. Assuming that the dielectric constant in the free state of _t and T = 0 is ε ^T , it can be expressed by the following relationship: S = s ^E T + d _t E D = d ^T + ε ^T E

Here, when there is no ink in the ink flow path, a suffix 0 is added, and when ink is present, a suffix 1 is added, and the electric displacement D is expressed as follows: D ₀ = dT ₀ + epsilon ^T E can be expressed as ^{_{D 1 = dT 1 + ε T}} E, the difference between both (D ₀ -D ₁₎ is a _{D 0 -D 1 = d (T} 0 -T 1).

The difference between the electric displacements can be converted into the difference between the electric charges, and the difference between the stresses can be converted into the difference between the pressures. I understand. Figure 3 shows a 7mm x 20mm chip with 32 nozzles of 300dpi on both sides,
In a print head having a 0.5 mm x 3.5 mm ink pressurizing chamber,
When a voltage pulse as shown in FIG. 9 of 36 V × 30 μs is applied using an aqueous ink of 2 cps at room temperature, the charge amount waveform measured by the circuit configuration of FIG. 1 is converted into a pressure waveform. The time at which the application of the voltage pulse is started is set to time = 0, and the pressure value is shown in units of MPa. (A) is a diagram showing a pressure waveform in a state in which the ink flow path is normally filled with ink, and (b) is a state in which a bubble having a size several tens of times the size of the ejected ink droplet exists in the ink pressurizing chamber. And (c) is a diagram showing a pressure waveform in a state where the nozzle is completely clogged.

A comparison between the figures (a) and (b) shows that the change in pressure is reduced because the volume change is absorbed by the bubbles. Since the manner in which the pressure change is absorbed changes depending on the size of the bubble, the size of the bubble can be estimated by looking at the waveform. Comparing the figures (a) and (c), it can be seen that when the nozzle is clogged, the ink on the nozzle side cannot move and the pressure change is large. In particular, it greatly increases on the positive pressure side, and is accompanied by vibration later. Even if the ink supply unit side is clogged, the fluid resistance is substantially the same as that of the nozzle side, and therefore shows almost the same change. FIG. (C) shows a pressure waveform in a state where the nozzle is completely clogged. However, even if the nozzle is not completely clogged, if the fluid resistance is increased, the pressure change is correspondingly large.

Note that it is difficult to measure the amount of inflowing electric charge in a state where there is no ink in the ink flow path in a normal use state because it is necessary to remove the ink and measure it. It is preferable to measure and store it in a ROM or the like built in a printer or recorder. As shown in FIG. 3, the case where air bubbles exist in the ink flow path,
In the case where dust and the like are present and the fluid resistance is increasing,
The direction of the pressure change is reversed as compared with the normal pressure waveform. Therefore, both abnormalities can be easily distinguished by examining the magnitude of the pressure waveform or the peak value.

In a state where the recording head cannot discharge ink droplets normally, the pressure drop in the ink pressurizing chamber due to the presence of air bubbles in the ink flow path and the fluid due to the presence of dust and the like in the ink flow path. An increase in resistance, adhesion of ink to the nozzle surface around the nozzle, and the like are raised. As described above, the former two can be detected by grasping the pressure waveform by measuring the amount of inflow charge when the piezoelectric element is driven.
For the detection, the most effective method is to provide a threshold value for the peak value, and to determine an abnormality when the threshold value is exceeded. For example, when the peak value of the normal pressure exceeds the peak value of the positive pressure value + 10%, the fluid resistance increases due to dust or the like. When the peak value of the normal pressure value does not reach -10%, the residual bubbles remain. It is a method. Note that it is also effective to use an average value of, for example, 10 μs before and after the peak position in order to reduce the influence of noise and the like.

The pressure waveform and its magnitude change due to the influence of the shape of the recording head, the driving conditions of the piezoelectric element, the change in the viscosity of the ink due to the temperature, and the like. It is necessary to obtain and change or correct as necessary. [Embodiment of Recording Apparatus] In this embodiment of the recording apparatus, the recording head having the configuration shown in FIG. 1 is mounted on the recording apparatus shown in FIG. The pressure waveform in the chamber is measured and compared with the pressure waveform in a normal state to check whether the recording head is normal. If it is determined that the recording head is normal, the apparatus waits for operation. If it is determined that the pressure factor is not normal, the failure factor removing unit is driven according to the content of the abnormality, and the pressure waveform of the ink pressurizing chamber is measured again.
As a result, when it becomes normal, it stands by for operation. If the cause of the failure still remains, the cause of the failure is displayed to notify that the device is abnormal.

In a recording apparatus equipped with a recording head showing a pressure waveform as shown in FIG. 3, a threshold value is set at ± 10% of the peak value on the positive pressure side in FIG. In this case, an increase in fluid resistance due to dust, etc.,
When the value was less than the value, the defective factor removing means was driven as bubbles remained. As a result, the influence of intentionally introduced bubbles and dust is reliably detected and removed, and no abnormality is caused in the printing characteristics.

In the above embodiment, the inspection of the recording head is performed when the power of the recording apparatus is turned on. However, the inspection may be performed when the recording paper is sent out or when the recording paper is transported. If the recording head is inspected at such a timing, it is possible to detect an abnormality of the recording head without lowering the operation efficiency of the recording apparatus, and it is possible to obtain a recording apparatus with good operation efficiency and high reliability.

Further, since the viscosity of the ink greatly changes with respect to the temperature, it is necessary to correct the setting of the threshold value in accordance with the temperature when the temperature change is large.

[0038]

According to the present invention, at least an ink pressurizing chamber for pressurizing ink, an ink supply path for supplying ink to the ink pressurizing chamber, and an ink pressurized in the ink pressurizing chamber are ejected. The recording head has a plurality of ink flow paths each including a nozzle and a piezoelectric element as a means for pressurizing ink on a side wall of the ink pressurizing chamber. Since there is provided a means for measuring the amount of charge that has flowed in, the pressure of the ink in the ink pressurization chamber adjacent to the piezoelectric element is measured by the amount of charge,
By associating the temporal change in the pressure of the ink pressurizing chamber with the applied voltage pulse, it is possible to estimate and determine whether or not a change in the situation has occurred in the ink flow path.

Therefore, the function of the recording head can be self-diagnosed. According to the second aspect of the present invention, since a trouble generated in the ink flow path is detected based on the measured pressure of the ink in the ink pressurizing chamber, it is possible to perform a self-diagnosis of the trouble of the recording head. Therefore, it is possible to provide a recording head having a function of self-diagnosing a trouble in the recording head.

According to the third aspect of the present invention, since a problem that occurs in the ink flow path is an increase in fluid resistance of the ink flow path due to residual air bubbles or dust in the ink flow path, a large problem that occurs in the recording head is obtained. Part of the trouble can be detected. Therefore, it is possible to provide a recording head having a function of self-diagnosing most troubles in the recording head.

According to a fourth aspect of the present invention, in the printing apparatus provided with the printing head according to the third aspect and the trouble solving means, the detection of the trouble occurring in the ink flow path is performed by turning on the power of the printing apparatus. When the recording paper is sent out or when the recording paper is transported, it is not necessary to use the time for printing for trouble detection. Therefore, it is possible to provide a recording device capable of performing trouble detection and trouble elimination measures without lowering the printing efficiency.

According to the fifth aspect, when the presence of bubbles in the ink flow path is detected, the pressure of the ink in the ink pressurizing chamber is measured after activating the trouble solving means for removing the bubbles. It is equipped with a means to re-examine the presence or absence of air bubbles and to indicate the presence of air bubbles when air bubbles are detected again, so that if the removal means works effectively, the recording device will be in a normal state If the removal cannot be performed even when the removing means is operated, the information is displayed, so that printing in that state can be avoided.

Therefore, it is possible to provide a recording apparatus capable of clearly distinguishing between a normal state and an abnormal state by taking self-diagnosis of bubbles remaining and taking measures to remove the bubbles.
According to the sixth aspect, when an increase in the fluid resistance of the ink flow path due to dust is detected, the pressure of the ink in the ink pressurizing chamber is measured after activating the trouble solving means for removing dust. A means for re-examining the presence or absence of an increase in the fluid resistance of the ink flow path due to dust and, when re-detecting an increase in the fluid resistance of the ink flow path due to dust, indicating that there is an increase in the fluid resistance of the ink flow path due to dust, So we have
When the removing means works effectively, the recording apparatus is in a normal state, and when the removing is not possible even when the removing means is operated, it is displayed, so that printing in that state can be avoided.

Accordingly, it is possible to provide a recording apparatus capable of clearly distinguishing between a normal state and an abnormal state by taking self-diagnosis of an increase in fluid resistance and taking measures to eliminate the increase in fluid resistance.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of an embodiment of a recording head according to the present invention.

FIGS. 2A and 2B show an example of a charge amount waveform obtained by an embodiment, in which FIG. 2A is a diagram showing a charge amount waveform of a charge amount Q ₀ in a reference state, and FIG. Diagram showing a charge amount waveform of charge amount Q ₁ in a filled state

FIG. 3 is a diagram showing a time change of the pressure of the ink pressurizing chamber obtained from the charge amount data measured by the embodiment, and (a) is a diagram showing a time change of the pressure in a normal print head;
(B) is a diagram showing the time change of the pressure when a large bubble exists, and (c) is a diagram showing the time change of the pressure when the nozzle is completely clogged.

FIG. 4 is a partial cross-sectional perspective view illustrating a configuration of an example of an inkjet recording apparatus.

5A and 5B show an example of a nozzle arrangement and recording dots of a recording head, wherein FIG. 5A is a nozzle arrangement diagram and FIG. 5B is a recording dot arrangement diagram.

FIG. 6 is a sectional view showing the structure of an example of a recording head.

FIG. 7 is a diagram for explaining the operation of the recording head.
(A) is a sectional view showing a standby state, (b) is a sectional view at the time of pulse application, and (c) is a sectional view at the time of ink ejection.

FIG. 8 is a drive circuit diagram of a conventional recording head.

FIG. 9 is a voltage waveform diagram showing an example of a driving pulse of a recording head.

10A and 10B show a positional relationship between a recording head and a protection device in the inkjet recording apparatus, wherein FIG. 10A is a partial sectional view showing a standby state, FIG. 10B is a partial sectional view showing a state immediately before shifting to a printing operation, (C) is a partial cross-sectional view showing an operation state of the trouble solving means, and (d) is a partial cross-sectional view showing a state of cleaning the nozzle surface of the recording head.

[Description of Signs] 1 Recording head 11 Substrate 12 Vibration plate 13 Ink supply unit 14 Ink pressurizing chamber 15 Nozzle 16 Piezoelectric element 2 Carriage 3 Recording paper 4 Carriage transport means 41 Motor 42, 43 Pulley 44 Belt 45 Spacing shaft 5 Paper Feeding means 51 Paper feed roller 52 Pinch roller 6 Protector 61 Wiper 62 Cap 63 Pump 64 Pump drive 7 Frame 81, 82 Transistor 83 Resistance 84 Charge amplifier 9 Ink 91 Ink droplet

Claims (6)

[Claims] An ink pressurizing chamber for pressurizing ink, an ink supply path for supplying ink to the ink pressurizing chamber, and a plurality of nozzles for discharging ink pressurized in the ink pressurizing chamber. In the ink jet recording head having a piezoelectric element as means for pressurizing ink on the side wall of the ink pressurizing chamber, the amount of electric charge flowing into the electrode of the piezoelectric element with the driving of the piezoelectric element An ink jet recording head comprising means for measuring, and measuring the pressure of ink in an ink pressurizing chamber adjacent to a piezoelectric element based on the amount of charge. 2. The ink jet recording head according to claim 1, wherein a trouble occurring in the ink flow path is detected based on the measured pressure of the ink in the ink pressurizing chamber. 3. The ink jet recording head according to claim 2, wherein the trouble that has occurred in the ink flow path is an increase in fluid resistance of the ink flow path due to residual air bubbles or dust in the ink flow path. 4. An ink jet recording apparatus comprising the ink jet recording head according to claim 3, and a trouble solving means, wherein the detection of a trouble occurring in the ink flow path is performed when the power of the ink jet recording apparatus is turned on. An ink jet recording apparatus, which is carried out when paper is sent out or when recording paper is conveyed. 5. When the presence of bubbles in the ink flow path is detected, a trouble elimination means for removing the bubbles is operated, and then the pressure of the ink in the ink pressurizing chamber is measured to determine the presence or absence of the bubbles. 5. The ink-jet recording apparatus according to claim 4, further comprising means for re-inspection and displaying the presence of air bubbles when air bubbles are detected again. 6. When the increase in the fluid resistance of the ink flow path due to dust is detected, a trouble elimination means for removing the dust is operated, and then the pressure of the ink in the ink pressurizing chamber is measured to measure the ink pressure due to the dust. It is provided with means for re-examining the presence or absence of an increase in the fluid resistance of the ink flow path, and, when re-detecting the increase in the fluid resistance of the ink flow path due to dust, indicating that the increase in the fluid resistance of the ink flow path due to dust exists. The ink jet recording apparatus according to claim 4, wherein: