JP2000158670A - Ink-jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely execute normal printing at the time of printing and eliminate a waste of a recording medium, ink and time. SOLUTION: An electrode plate pair (electrode plate in the drawing) 101 is arranged adjacent to a nozzle 15 in an ink discharge direction of the nozzle 15 of an ink-jet recording head 1. A coil 102 and an oscillator 103 are connected in series to the electrode plate pair 101, thereby constituting a resonant circuit. While no ink drop 91 is present between the electrode plate pair 101, an oscillation frequency of the oscillator 103 is adjusted to render the resonant circuit in a resonance state. When the ink drop 91 passes between the electrode plate pair 101 in this state, the resonant circuit shifts out of the resonance state. The passing of the ink drop and a size of the ink drop are detected by detecting the shift. If an abnormality takes place, the abnormality is removed by a failure cause-removing means. All nozzles are checked before printing, thus enabling normal printing.

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 perspective view, partly in section, 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. A carriage 2 on which an ink jet recording head (hereinafter abbreviated as a recording head) is mounted is sent by a carriage transporting unit 4 in a direction perpendicular to a transport direction of a recording sheet 3 as a print medium. Printing is performed line by line by ink droplets ejected from the nozzles.

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, with adjacent nozzles spaced 1/150 inch vertically and 9/300 horizontally.
Inches. The ink is ejected perpendicularly to the surface of the recording paper 3 from nozzles of the recording head on the lower surface of the carriage 2 in FIG. 4 to form print dots. Therefore, 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 subsequent line feed.

FIG. 6 is a cross-sectional view showing an example of the structure of a recording head, FIG. 7 is a diagram for explaining the operation of the recording head, FIG. 6A is a cross-sectional view showing a standby state, and FIG. FIG. 3C is a cross-sectional view when applying an ink, and FIG.

[0006] The recording head 1 shown in FIG. 6 is a recording head of a printing system called a Kaiser type, in which a groove formed in a substrate 11 and a vibration plate 12 form an ink supply section 13, an ink pressurizing chamber 14, and the like. A plurality of ink flow paths each including a nozzle 15 are formed, and a piezoelectric element 16 is bonded to an outer surface of the vibration plate 12 corresponding to the ink pressurizing chamber.

The substrate 11 is made of, for example, a silicon wafer and has grooves etched 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.

A common electrode made of ITO or gold is previously formed on the surface of the vibration plate 12 to which the piezoelectric element 16 is bonded by a vacuum evaporation method or a sputtering method. A flexible printed board (hereinafter abbreviated as FPC) is connected by a method such as soldering (the common electrode and the FPC are not shown in FIGS. 6 and 7). When a voltage is applied between the common electrode and the FPC, the piezoelectric element 16 is deformed. Piezoelectric element 16
When a voltage of a polarity that shortens the length direction of the
Due to the bimorph effect between the piezoelectric element 12 and the piezoelectric element 16, the diaphragm 12
Deforms toward the ink pressurizing chamber 14 and reduces the volume of the ink pressurizing chamber 14.

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 waveform of a voltage applied to the piezoelectric element 16. An initial state in which the first transistor 81 is on and the second transistor 82 is off is
This corresponds to the standby state shown in FIG. 7A, and a voltage is applied. When the ON and OFF states of the first and second transistors are reversed, the state where the voltage is reduced is the negative pressure state shown in FIG. 7B, and the ink 9 is supplied from the ink supply unit 13. When the voltage is returned to the initial voltage application state again and the voltage is rapidly increased, the piezoelectric element 16 contracts again, the internal pressure of the ink pressurizing chamber 14 increases, and the state shown in FIG. . FIG. 7 shows an initial state when this state is stabilized.
(A).

As an ink jet recording system other than the Kanzer 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 rapid pressure rise when the ink is heated and vaporized, and has a feature that the recording head can be miniaturized.

In the above two ink jet recording systems, 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, which hinders the rise in pressure required to eject ink droplets, and dust increases the fluid resistance of the ink flow path, preventing the necessary pressure from being transmitted 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 printing defects.
Ink suction means using a negative pressure generating mechanism such as
The ink 9 in the ink flow path is forcibly sucked from the nozzles 15 of the recording head 1 by the negative pressure, and bubbles and dust in the ink flow path are removed by the flow of the ink.

In addition, printing defects may 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 the ink suction means using the 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 by 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,
It returns to the state of 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, and as shown in FIG.
The piston of 63 is lowered, the pressure in the cylinder is reduced, and the pressure in the cap 62 is reduced to suck the ink in the ink flow path of the recording head 1 through the nozzle into the cap 62 to remove bubbles and dust in the ink flow path. Remove. Ink sucked is cap
It is discharged by a pump 63 via 62.

Here, the negative pressure generating mechanism using the pump 63 and the pump driving section 64 has been described. However, another type of negative pressure generating mechanism may be used. After this, the cap 62
It is lowered to the state of 10 (d). In this state,
The cap 62 is separated from the recording head 1 but the wiper 61
Is located at a position where it can come into contact with the nozzle surface of the recording head 1. By moving the carriage 2, the nozzle surface of the recording head 1 is wiped by the wiper 61, and ink and dust adhering to the nozzle surface are removed.

[0020]

The maintenance command is issued in the recording apparatus according to the prior art described above because a user finds a printing defect when a trouble occurs in the recording head and performs an operation of removing the printing defect. This is either a case where the printing operation is performed or a case where a printing defect removing operation is periodically performed.

For this reason, in the conventional recording apparatus, printing without recognizing an abnormality and re-printing due to a printing defect may occur, and the recording medium and ink may be wasted, and the extra printing time may be consumed. However, there is a problem that a maintenance command is issued periodically even though there is no abnormality and ink and the like are wasted.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems by detecting an abnormality in the ink ejection state before printing and eliminating the abnormality. It is an object of the present invention to provide a recording apparatus which does not waste ink, ink and time.

[0023]

According to the present invention, at least an ink pressurizing unit, a nozzle unit for discharging ink pressurized by the ink pressurizing unit as ink droplets, and an ink pressurizing unit are controlled. A control unit, and a defective cause removing and protecting unit for discharging the ink droplets normally. The ink droplets are discharged from the nozzle unit by driving the ink pressurizing unit controlled by the control unit. In an ink jet recording apparatus for forming and recording ink dots on a substrate, an electrode plate pair that can be arranged at an ink ejection position of a nozzle portion, a resonance circuit that resonates with a capacitance formed by the electrode plate pair, Means for detecting a change in the resonance state, and detection means for detecting a change in the resonance state of the resonance circuit when the ink droplet passes between the electrode plate pairs. A change in the resonance state of the resonance circuit when the ink droplets ejected from the nozzles pass between the plate pairs is detected by the detection means, so that whether or not the ink droplets are ejected from the nozzle portion and whether the ink droplets are ejected are detected. The size of the dropped ink droplet is detected (the invention of claim 1).

Since whether or not the ink droplet is ejected from the nozzle portion and the size of the ejected ink droplet are detected, it is determined whether or not the ink droplet is normally ejected from the nozzle portion. It is possible to determine whether it is necessary to operate the failure cause elimination and protection means.

According to the first aspect of the present invention, before recording on the print medium, the presence or absence of the ejected ink droplets and the size of the ejected ink droplets of all the nozzles in the nozzle portion are detected (the second invention). Before recording on the print medium, the status of all nozzles in the nozzle section is ascertained.If there is any abnormality, make sure to operate the defect cause elimination means before recording on the print medium to remove the abnormality. can do.

At least an ink pressurizing unit, a nozzle unit for discharging the ink pressurized by the ink pressurizing unit, a control unit for controlling the ink pressurizing unit, and a control unit for normally discharging ink droplets An ink jet recording apparatus which has a defect cause removing and protecting means, ejects ink droplets from a nozzle portion by driving an ink pressurizing means controlled by a control section, and forms ink dots on a print medium to record. A first pair of electrode plates at an ink discharge position of the nozzle portion, a second pair of electrode plates, a first pair of electrode plates, and a second pair of electrode plates at a rear side in a traveling direction of ink droplets discharged from the nozzle portion. A resonance circuit that resonates with an electrostatic capacitance formed by connecting the pairs in parallel or in series; and a detection unit that detects a change in the resonance state of the resonance circuit, and a discharge ink droplet flows between the first electrode plate pair. Pass By detecting the change in the resonance state of the resonance circuit at the time, the presence or absence of the ejected ink droplet and the size of the ejected ink droplet are detected, and the ejected ink droplet passes between the first electrode plate pair. The detection means detects a time difference between a change in the resonance state of the resonance circuit when the detection is performed and a change in the resonance state of the resonance circuit when the discharge ink droplet passes between the second pair of electrode plates. The speed and the deflection state of the ejected ink droplet are detected (the invention of claim 3).

In addition to the presence / absence of ink droplet ejection and the size of the ejected ink droplet, the ejection speed and deflection state of the ink droplet are detected, so that a normal ink droplet is ejected from all the nozzles of the nozzle portion. It can be more accurately determined whether or not there is.

In any one of the first to third aspects of the present invention, an ink-repellent film is formed on the surface of the pair of electrode plates (the fourth aspect of the invention). Since the ink-repellent film is formed on the surface of the pair of electrode plates, it is possible to prevent the deflected ink droplet from adhering to and remaining on the surface even if it contacts the pair of electrode plates.

In any one of the first to fourth aspects of the present invention, the electrode plate pair is disposed at an end of the recording apparatus on the opposite side of the position where the defect cause removing and protecting means is disposed. (The invention of claim 5). Since the electrode plate pair is arranged at the end of the recording device on the side opposite to the defect cause removing and protecting means, the entire recording device can be compactly assembled.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a recording apparatus according to the present invention, a pair of electrode plates is arranged at a position where a nozzle ejects ink droplets, and a resonance circuit is formed using a capacitor composed of the pair of electrode plates. A change in the capacitance value of the electrode plate pair when an ink droplet passes between the electrodes is detected as a change in the resonance state,
Based on the change in the resonance state, it is determined whether or not the ink droplet is ejected and whether or not the size of the ejected ink droplet is normal, and a defect cause removing unit (described as the protection device 6 in the related art). Is determined.

An embodiment will be described below. It is to be noted that the same reference numerals are used for portions having the same functions as the conventional technology.

[First Embodiment] FIG. 1 is a partial perspective view showing a principle structure of a first embodiment of a recording apparatus according to the present invention, and FIG. 2 is a sectional view showing the whole structure.

An electrode plate pair (only electrode plate in FIG. 1) 101 for determining whether or not the ink droplet 91 is normally ejected from the nozzle 15 of the recording head 1 is provided by a nozzle of the recording head 1.
It is arranged adjacent to the recording head 1 in 15 ink ejection directions (below the nozzle 15 in FIG. 1). This electrode plate pair 10
1 has a coil 102 and an oscillator 103 connected in series,
A resonance circuit is formed. This resonance circuit consists of an electrode plate pair
The oscillation frequency of the oscillator 103 is adjusted so that a resonance state occurs when no ink droplet 91 exists during the period 101. In this state, when the ink droplet 91 discharged between the electrode plate pair 101 enters, the capacitance value of the electrode plate pair 101 changes in accordance with the volume of the ink droplet 91, and the change amount becomes Accordingly, the resonance state of the resonance circuit shifts. By detecting this shift, the amount of change in the capacitance value of the electrode plate pair 101, that is, the volume of the portion of the ink droplet 91 between the electrode plate pairs 101 can be grasped. If the resonance state does not change at all, it indicates that the ink droplet 91 does not exist, that is, the nozzle is in a non-ejection state or is deflected and does not reach between the electrode plate pair 101. A smaller change indicates that the ink drop is small or deflected, and only a portion of the ink drop is between the electrode plate pairs 101.

Here, the capacitance value of the electrode plate pair 101 is C,
Assuming that the inductance value of the coil 102 is L and the resonance frequency is f, f = 1 / [2π (LC) ^1/2 ].

An ink droplet 91 is ejected from the nozzle 15 immediately above the electrode plate pair 101, and when the ink droplet 91 passes between the electrode plate pair 101, the dielectric constant ε _i of the ink droplet becomes equal to the dielectric constant ε _{0 of} air. Therefore, the capacitance value of the capacitor formed by the electrode plate pair 101 increases by an amount proportional to the volume of the ink droplet. When this increment and [Delta] C, the resonance frequency f _i when the ink droplets are passing is smaller than the f _i = 1 / [2π [L (C + ΔC)] ^1/2], and, f.

The deviation of the resonance frequency can be detected as the voltage amplitude at both ends of the coil 102 or the voltage amplitude between the electrode plate pairs 101 when the frequency of the oscillator is fixed at f. When there is no deviation, that is, in the resonance state, this voltage amplitude shows the maximum value. However, when the voltage shifts from the resonance state, the voltage amplitude decreases as the shift increases. Therefore, the size of the ink droplet 91 can be detected as the voltage amplitude by determining the displacement, that is, the relationship between the voltage amplitude and the size of the ink droplet 91 passing between the electrode plate pairs 101 in advance. .

One example of specific dimensions and the like is as follows.
The electrode plate 101 is made of an aluminum plate, the size is 5 mm square, the interval between the electrode plates is 150 μm, and the capacitance value of the electrode plate pair 101 is about 4.5 pF. The relative permittivity of the ink droplet is about 20, which is sufficiently larger than the relative permittivity of 1 of air.

Further, on the surface of the electrode plate of the electrode plate pair 101,
A water-repellent ink-repellent film containing a fluorine compound is formed so that even if the ink droplet 91 contacts the surface, the ink does not adhere and remain there. This ink-repellent film is also effective when the ink is oily.

An ink droplet ejection state detecting means (ink droplet detecting device in FIG. 2) comprising such an electrode plate pair 101 and the like 100
The check of the ejection state of all the nozzles of the recording head 1 is executed immediately before the recording on the recording medium is started.
When the ink droplet ejection state detecting means 100 detects an abnormality in the ejection state of the ink droplet 91, the defect cause removing means (protection device in FIG. 2) 6 operates, and after sucking ink from the nozzle 15, the nozzle 15 Is wiped off with the wiper 61 to restore the ink droplet 91 to a state where it can be ejected normally.

Such an ink droplet ejection state detecting means 100
Means, as shown in FIG.
Is located at the end of the recording device opposite to the installation position. Of course, this position must be other than the print position on the recording medium. Further, an ink absorber 110 for collecting the ejected ink droplets 91 is provided on the ink droplet outlet side of the electrode plate pair 101. The ink absorber 110 is
It consists of a sponge or the like that absorbs and stores ink well.

As is apparent from the above description, according to this embodiment, the ink droplet ejection state detecting means 100
It is detected whether or not the ink droplet 91 has been ejected from the nozzle 15 and whether or not the ejected ink droplet 91 has a predetermined size, and cleaning of the ink flow path including the nozzle surface of the recording head 1 is performed. Is determined, the necessary cleaning is executed by the defect cause removing means 6, and the normal ink ejection state is restored. The ink droplet ejection state is checked immediately before recording on the print medium, and cleaning is performed if necessary. Therefore, after checking the printed result, an operation command of the defect cause removing means 6 is input to perform cleaning or periodic cleaning. As compared with the case where cleaning is performed at a time, waste of recording paper and ink is reduced, and wasteful time for re-printing can be eliminated.

[Second Embodiment] FIG. 3 shows a second embodiment of the present invention.
FIG. 3 is a partial perspective view showing the principle configuration of the embodiment. In this embodiment, a second electrode plate pair (simply an electrode plate in FIG. 3) 101a is added to the first embodiment, and the electrode plate pair 101 of the first embodiment and the second electrode plate pair 101a are combined. In parallel, a resonance circuit is formed by connecting to the coil 102 and the oscillator 103. The second electrode plate pair 101a is located at a predetermined distance from the electrode plate pair 101 on the side of the ink droplet traveling direction. The shape of the second electrode plate pair 101a is the same as that of the electrode plate pair 101 of the first embodiment.

In the circuit configuration as described above, the frequency of the oscillator 103 is adjusted so as to be in a resonance state when the ink droplet 91 does not exist between any pair of electrode plates. In this state, if an ink droplet enters between the electrode plate pairs, the circuit is shifted from the resonance state as in the case of the first embodiment, and both ends of the coil 102 or the electrode plate pairs 101 and 101a. The voltage amplitude between them becomes smaller.

The ink droplet 91 discharged from the nozzle 15 first passes between the first pair of electrode plates 101, and then passes between the second pair of electrode plates 101a if not so deflected. . Therefore, if the ink droplet 91 is ejected, the resonance state is usually shifted twice for one ejection of the ink droplet 91. By the first shift, that is, the passage of the ink droplet 91 between the first electrode plate pair 101, the presence / absence of ink droplet ejection and the size of the ink droplet are detected in the same manner as in the first embodiment. The speed and deflection state of the ink droplet are detected by the passage of the ink droplet 91 between the second pair of electrode plates 101a. The speed of the ink droplet is calculated from the distance between the two electrode plates and the time difference between the two shifts, and if there is a deflection, the subsequent shift is reduced or eliminated. In this example,
The distance between both electrode plate pairs is 1 mm.

According to the experience of the inventor, when the ink droplet is small, the speed of the ink droplet is reduced. According to this embodiment, similarly to the first embodiment, in addition to the detection of the ejection of the ink droplet and the detection of the size of the ink droplet, the speed and the deflection state of the ink droplet can be detected. Therefore, the abnormality of the ejection of the ink droplet can be grasped more accurately,
It is possible to more accurately determine whether to perform cleaning of the ink flow path including the nozzle surface.

[0046]

According to the present invention, at least an ink pressurizing unit, a nozzle unit for discharging the ink pressurized by the ink pressurizing unit as ink droplets, and a control unit for controlling the ink pressurizing unit are provided. And a means for removing and protecting the cause of failure for normal ejection of ink droplets. The ink droplets are ejected from the nozzles by the driving of the ink pressurizing means controlled by the control unit, and the ink dots are printed on the print medium. In an ink-jet recording apparatus for forming and recording ink, a pair of electrode plates that can be arranged at the ink discharge position of the nozzle portion, a resonance circuit that resonates with the capacitance formed by the pair of electrode plates, and a resonance state of the resonance circuit Means for detecting the change, and detecting means for detecting a change in the resonance state of the resonance circuit when the ink droplet passes between the pair of electrode plates. The detection means detects a change in the resonance state of the resonance circuit when the ink droplets ejected from the nozzle pass through, and determines whether or not the ink droplets are ejected from the nozzle portion and the size of the ejected ink droplets. Is detected, it is possible to determine whether or not the ink droplet is normally ejected from the nozzle portion, and it is possible to determine whether or not it is necessary to operate the failure cause elimination and protection means. Therefore, it is possible to provide a recording apparatus that can perform normal printing reliably and does not waste recording media, ink, or time (the invention of claim 1).

According to the first aspect of the present invention, the presence or absence of the ejected ink droplets and the size of the ejected ink droplets of all the nozzles of the nozzle portion are detected before recording on the print medium. Can be reduced. Therefore, it is possible to provide a recording device that can perform normal printing more reliably and does not waste recording media, ink, or time (the invention of claim 2).

Further, at least an ink pressurizing unit, a nozzle unit for discharging the ink pressurized by the ink pressurizing unit, a control unit for controlling the ink pressurizing unit, and a control unit for discharging the ink droplets normally. An ink jet recording apparatus which has a defect cause removing and protecting means, ejects ink droplets from a nozzle portion by driving an ink pressurizing means controlled by a control section, and forms ink dots on a print medium to record. A first electrode plate pair at an ink discharge position of a nozzle portion, a second electrode plate pair at a rear side in a traveling direction of ink droplets discharged from the nozzle portion, and a first electrode plate pair and a second electrode plate. A resonance circuit that resonates with the capacitance formed by connecting the pairs in parallel or in series; and a detection unit that detects a change in the resonance state of the resonance circuit, and a discharge ink droplet flows between the first electrode plate pair. Pass By detecting the change in the resonance state of the resonance circuit at the time, the presence or absence of the ejected ink droplet and the size of the ejected ink droplet are detected, and the ejected ink droplet passes between the first electrode plate pair. The detection means detects a time difference between a change in the resonance state of the resonance circuit at the time of performing the operation and a change in the resonance state of the resonance circuit when the discharge ink droplet passes between the second pair of electrode plates. Since the speed and the deflection state of the ejected ink droplet are detected, it can be more accurately determined whether or not the normal ink droplet is ejected from all the nozzles of the nozzle portion. Therefore, it is possible to provide a recording apparatus that can perform normal printing more reliably and does not waste recording media, ink, or time (the invention of claim 3).

In any one of the first to third aspects of the present invention, since the ink repellent film is formed on the surface of the pair of electrode plates, the deflected ink droplet contacts the pair of electrode plates. Even so, it is possible to avoid adhesion and remaining on the surface.
Therefore, it is possible to prevent ink droplets from adhering to the electrode plate and hinder the detection of the passage of ink droplets, and efficiently and accurately determine whether or not normal ink droplets are ejected from all the nozzles of the nozzle portion. (The invention of claim 4).

In any one of the first to fourth aspects of the present invention, the electrode plate pair is disposed at the end of the recording apparatus opposite to the position where the cause of failure removal and protection means is disposed. Therefore, the entire recording apparatus can be made compact. Therefore, it is possible to provide a compact recording apparatus that can perform normal printing and does not waste recording media, ink, or time (the invention of claim 5).

[Brief description of the drawings]

FIG. 1 is a partial perspective view showing a principle configuration of a first embodiment of a recording apparatus according to the present invention.

FIG. 2 is a cross-sectional view showing the entire configuration of the first embodiment.

FIG. 3 is a partial perspective view showing a principle configuration of a second embodiment.

FIG. 4 is a partial cross-sectional perspective view showing an example of a configuration of a recording apparatus according to a conventional technique.

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 cross-sectional view illustrating a configuration 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 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 recording apparatus, and FIG. 10A is a partial cross-sectional view showing a standby state;
(B) is a partial sectional view showing a state immediately before shifting to a printing operation, (c) is a partial sectional view showing an operating state of the trouble interfering means, and (d) is a part showing a state in which the nozzle surface of the recording head is cleaned. Sectional view

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording head 11 Substrate 12 Vibration plate 13 Ink supply part 14 Ink pressurization room 15 Nozzle 16 Piezoelectric element 2 Carriage 3 Recording paper 4 Carriage conveyance means 41 Motor 42, 43 Pulley 44 Belt 45 Spacing axis 5 Paper feed means 51 Paper feed Roller 52 Pinch roller 6 Protector 61 Wiper 62 Cap 63 Pump 64 Pump driver 7 Frame 81, 82 Transistor 83 Resistance 9 Ink 91 Ink drop 101, 101a Electrode plate 102 Coil 103 Oscillator 110 Ink absorber

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 2C056 EA14 EA25 EB03 EB08 EB40 EC03 EC23 EC24 EC57 EC58 FA03 FA04 FA10 JA01 JA13 JB04 JC10 JC20 JC23 KD06 2C057 AF71 AG44 AG46 AL03 AL19 AL40 AM03 AM31 AN01 DB01 DB03 DC08 DD02

Claims (5)

[Claims] At least an ink pressurizing unit, a nozzle unit for ejecting ink pressurized by the ink pressurizing unit as ink droplets, a control unit for controlling the ink pressurizing unit, and a normal operation of the ink droplets A means for removing and protecting a cause of failure for ejection, and ejecting ink droplets from a nozzle unit by driving an ink pressurizing means controlled by a control unit to form and record ink dots on a print medium In an ink jet recording apparatus, a pair of electrode plates (hereinafter, referred to as an electrode plate pair) that can be arranged at an ink discharge position of a nozzle portion, a resonance circuit that resonates with a capacitance formed by the electrode plate pair, Detecting means for detecting a change in the resonance state of the resonance circuit when an ink droplet discharged from the nozzle passes between the electrode plate pairs. An ink jet recording apparatus for detecting whether or not an ink droplet is ejected from the nozzle portion and detecting the size of the ejected ink droplet by detecting the ink droplet from the nozzle portion. 2. The ink jet recording apparatus according to claim 1, wherein the presence or absence of ejected ink droplets and the size of the ejected ink droplets of all nozzles of the nozzle portion are detected before recording on the print medium. . 3. An ink pressurizing unit, a nozzle unit for discharging ink pressurized by the ink pressurizing unit, a control unit for controlling the ink pressurizing unit, and a unit for discharging ink droplets normally. An ink jet recording apparatus which has a defect cause removing and protecting means, ejects ink droplets from a nozzle portion by driving an ink pressurizing means controlled by a control section, and forms ink dots on a print medium to record. A first electrode plate pair at an ink discharge position of the nozzle portion; a second electrode plate pair at a rear side in a traveling direction of ink droplets discharged from the nozzle portion; a first electrode plate pair and a second electrode plate. A resonance circuit that resonates with an electrostatic capacitance formed by connecting the pairs in parallel or in series; and a detection unit that detects a change in the resonance state of the resonance circuit, and a discharge ink droplet flows between the first electrode plate pair. pass The change in the resonance state of the resonance circuit is detected by the detection means, whereby the presence or absence of the ejected ink droplet and the size of the ejected ink droplet are detected, and the ejected ink droplet passes between the first electrode plate pair. The detection means detects a time difference between a change in the resonance state of the resonance circuit at the time of the change and a change in the resonance state of the resonance circuit when the discharge ink droplet passes between the second pair of electrode plates. An ink jet recording apparatus, wherein a speed and a deflection state of an ink droplet are detected. 4. The ink jet recording apparatus according to claim 1, wherein an ink repellent film is formed on the surface of the pair of electrode plates. 5. The ink jet recording apparatus according to claim 1, wherein the electrode plate pair is arranged at an end of the ink jet recording apparatus opposite to a position where the cause of failure removal / protection means is arranged. The inkjet recording device according to any one of the above.