JP2010000755A - Liquid ejection head, method for detecting defective nozzle of liquid ejection head, and image forming apparatus - Google Patents

Abstract

A liquid discharge head that can accurately and quickly detect a nozzle that has failed to discharge during liquid discharge, and an image forming apparatus that includes the liquid discharge head and can improve discharge stability.
A nozzle, an individual liquid chamber holding a liquid to be discharged, a pressure generating means generating energy for discharging the liquid, a common liquid chamber holding a liquid supplied to the individual liquid chamber, A liquid discharge head having a liquid supply path 105 for supplying a liquid from a common liquid chamber to an individual liquid chamber has two electrode members 106 and 107 in a liquid flow path, and at least one of the two electrode members is a liquid. It is arranged inside the supply path 105 and detects the discharge state of the nozzle from the potential difference between the two electrode members 106 and 107.
[Selection] Figure 2

Description

  The present invention relates to a liquid discharge head (recording head) used in an image forming apparatus including an inkjet printer and a plotter, a defective nozzle detection method for the liquid discharge head, and an image forming apparatus including a liquid discharge head having the defective nozzle detection method. Is.

A liquid discharge head used in an image recording apparatus such as a printer, a facsimile machine, a copying apparatus, or a plotter, or an ink jet recording apparatus used as an image forming apparatus includes a nozzle that discharges a liquid and an individual liquid chamber that holds the liquid to be discharged. A pressure generating source for generating energy for discharging the liquid, a common liquid chamber for holding the liquid to be supplied to the individual liquid chamber, and a liquid supply for supplying the liquid from the common liquid chamber to the individual liquid chamber And a droplet is ejected from the nozzle by applying a pressure to the individual liquid chamber from the pressure generating source.
If such a liquid ejection head is left for a long time without ejecting ink, the ink thickens in the vicinity of the nozzles, and normal ejection may not be possible.
Further, if ink is ejected continuously for a relatively short time, fine bubbles may be generated in the liquid chamber. If these bubbles remain in the liquid chamber and grow, ejection failure occurs as described above.
Regarding the bubbles, there are bubbles that are generated in the supply process of the ink supply system, in addition to those derived from the continuous driving of the pressure generation source. In addition, foreign matter may be mixed in the ink supply system due to insufficient cleaning or the like. When these bubbles / foreign substances reach the nozzles according to the flow of ink, it is not difficult to imagine that ejection failure will occur as described above.
As described above, when a specific nozzle channel is in a non-ejection state, for example, in an image forming apparatus such as an ink jet printer, an image defect such as white streaks occurring in the main scanning direction on a recorded image occurs. Undesirable for image quality. Therefore, when a nozzle having a discharge failure occurs, it is desirable to detect this promptly and take appropriate action.

Various techniques have been proposed in the past in order to solve the problems relating to the detection of the occurrence of nozzles with such ejection failure and the implementation of countermeasures against them (see, for example, Patent Documents 1 to 3).
In Patent Document 1, a light emitting element such as a laser oscillator or LED and a light receiving element such as a photodiode or a phototransistor are provided for the number of nozzle channels, and an ink is detected optically, that is, ink. A method for optically detecting the presence or absence of ejection is disclosed.
In Patent Document 2, a method is provided in which a pressure sensor is provided at a position where a droplet ejected from a liquid ejection head should land, and the presence or absence of a droplet ejected from its output signal is detected, that is, when an ink droplet has landed. A method for detecting the impact of the above is disclosed.
In Patent Document 3, a thermal sensor is provided at a position where a droplet ejected from a liquid ejection head should land, and the presence or absence of the ejected droplet is detected from its output signal, that is, a temperature change caused by the presence or absence of ink. A method of detecting is disclosed.
JP 2004-216339 A JP 2005-238683 A Japanese Patent No. 3248969

However, although the technique disclosed in Patent Document 1 has an advantage that precise detection is possible in units of one nozzle, there is a problem that the apparatus becomes large and the manufacturing cost becomes very high.
Further, the technique disclosed in Patent Document 2 has an advantage that detection is possible with a relatively simple configuration, but recently, due to the reduction in the size of the ejected liquid droplets accompanying the increase in resolution of the image forming apparatus, The sensor for detecting the pressure is also required to be highly sensitive. Therefore, as the nozzle miniaturization proceeds in the future, the manufacturing cost increases, which is a difficulty of this method.
Furthermore, although the technique disclosed in Patent Document 3 can also be realized with a simple configuration, the thermal method is generally less sensitive than other methods, and a long time is required to make a reliable determination. There was a difficulty that it was necessary to hang.
Accordingly, an object of the present invention is to provide a liquid discharge head that can accurately and quickly detect a nozzle that has failed to discharge during liquid discharge in consideration of the above-described situation, and to improve discharge stability by including this liquid discharge head. An object of the present invention is to provide an image forming apparatus.

In order to solve the above-mentioned problem, the invention described in claim 1 includes a nozzle that discharges a liquid, an individual liquid chamber that holds the liquid to be discharged, a pressure generating unit that generates energy to discharge the liquid, In a liquid discharge head having a common liquid chamber for holding liquid to be supplied to the individual liquid chamber and a liquid supply path for supplying liquid from the common liquid chamber to the individual liquid chamber, two electrode members are provided in the path through which the liquid flows. And a liquid discharge head in which at least one electrode member of the two electrode members is disposed inside the liquid supply path and detects a discharge state of the nozzle from a potential difference between the two electrode members.
According to a second aspect of the present invention, the liquid ejection head according to the first aspect is characterized in that the two electrode members are short-circuited when the nozzle is not ejected.
According to a third aspect of the invention, of the two electrode members, the elastic modulus of the electrode member arranged on the nozzle side is E1, and the elastic modulus of the electrode member arranged on the liquid supply side is E2
E1 <E2
The liquid discharge head according to claim 1, wherein

According to a fourth aspect of the present invention, when the nozzle is in a discharge state, the two electrode members are not in contact with each other, while the nozzle is in a non-discharge state and drives the pressure generating means. 4. The liquid discharge head according to claim 1, wherein the nozzle-side electrode member is deformed by a flow in the liquid supply path and causes contact between the two electrode members. 5.
In the invention according to claim 5, when the fluid resistance of the nozzle at the time of liquid ejection is R1, and the fluid resistance of the liquid supply path is R2,
R1 <R2
The liquid discharge head according to claim 1, wherein
According to a sixth aspect of the present invention, there is provided a liquid ejection head according to any one of the first to fifth aspects, comprising a defective nozzle detection method for detecting a non-ejection nozzle.

According to a seventh aspect of the present invention, in the image forming apparatus for forming an image on a sheet using a liquid, the liquid according to any one of the first to sixth aspects is used as a liquid discharge head used for image formation. An image forming apparatus including an ejection head is characterized.
According to an eighth aspect of the present invention, the two electrode members of the liquid discharge head are arranged in all the nozzle channels, and the detected potential is a center for controlling the liquid discharge head as a nozzle non-discharge state detection signal. The image forming apparatus according to claim 7, wherein the image forming apparatus is sent to an arithmetic unit and the non-ejection state of the nozzle can be confirmed in units of one nozzle.
According to a ninth aspect of the present invention, there is provided a nozzle for discharging a liquid, an individual liquid chamber for holding the liquid for discharging, a pressure generating means for generating energy for discharging the liquid, and an individual liquid chamber. In a defective nozzle detection method for a liquid discharge head having a common liquid chamber for holding liquid for supply and a liquid supply path for supplying liquid from the common liquid chamber to the individual liquid chamber, An electrode member, disposing at least one electrode member of the two electrode members inside the liquid supply path, deforming at least one of the two electrode members by pressure generated in the individual liquid chamber, The present invention is characterized by a defective nozzle detection method for a liquid discharge head that detects a discharge state of the nozzle by detecting a potential difference between two electrode members.

  According to the present invention, a defective ejection nozzle can be detected with a simple configuration, and thus a liquid ejection head having excellent ejection stability can be obtained.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view showing an ink jet printing apparatus to which the liquid discharge head of the present invention can be applied. FIG. 1 shows a general inkjet printing apparatus 1 which is an example of an image forming apparatus.
Inside the printing apparatus main body 1A of the inkjet printing apparatus 1, there are a carriage 11 movable in the main scanning direction, an inkjet recording type print head (or printing element) 12 mounted on the carriage 11, and the print head 12 immediately after. A lower endless conveying belt 13, an ink supply pipe (tube) 14 for supplying ink to the print head 12, an ink supply mechanism section including an ink sub-tank, an ink cartridge (not shown), and the like are accommodated. Yes.
A sheet stacking section 16 for stacking sheets P is provided at the lower part of the printing apparatus main body 1A, and a sheet discharge tray 27 is provided at the front of the apparatus. Further, as shown in FIG. 1, the inkjet printing apparatus 1 is provided with a high voltage power source 17, a charging roller 18, a belt conveying roller 23, a tension roller 24, a charge eliminating brush 25, and the like.
In the printing process of the ink jet printing apparatus 1, one sheet P is separated from a large number of sheets stacked on the sheet stacking unit 16 by the sheet feeding roller 19 and the sheet separation pad 20, and transferred while being guided by the conveyance guide 21. Is done. The sheet P is fed through a leading end roller 22 onto a conveyor belt 13 that circulates.
On the transport belt 13, ink droplets from the nozzles of the print head 12 land on the paper P, whereby desired printing (image formation) is performed. The printed paper P is discharged onto the paper discharge tray 27 through the paper guide 26. In order to pressurize the ink and form ink droplets, the print head 12 forms a liquid chamber wall surface with an electromechanical conversion element such as a piezoelectric element, and pressurizes the ink via a vibration plate. Yes.

FIG. 2 is a schematic sectional view showing a liquid discharge head according to the present invention. A nozzle (nozzle hole) 101 formed in a nozzle plate 100 of a recording head (printing head) 12 that discharges liquid communicates with an individual liquid chamber 102, and a pressure generation source 103 is disposed below the individual liquid chamber 102. Is installed. When a driving pulse is applied to the pressure generation source 103, the pressure inside the individual liquid chamber 102 increases and a droplet is ejected from the nozzle 101.
At this time, a region where the fluid resistance is partly high between the individual liquid chamber 102 and the common liquid chamber 104 for supplying the liquid to the individual liquid chamber 102, specifically, the individual liquid chamber 102 in FIG. By forming the region 105 having a low passage height with respect to the common liquid chamber 104, the driving force from the pressure generating source 103 can be efficiently used for liquid discharge.
In other words, if the fluid resistance of the nozzle during normal discharge is R1, and the fluid resistance of the flow path region 105 is R2, then R1 <R2 is established. With this configuration as a basic configuration, the nozzle portions are arranged in the depth direction of the paper surface by the number of nozzle channels. With this configuration, the discharge state of the nozzle 100 can be managed by software, so that a liquid discharge head having excellent discharge stability can be obtained.
The pressure generation source 103 may be a so-called piezo (piezoelectric) type in which ink is ejected by applying a voltage to the electrostrictive element and deforming the electrostrictive element, or a current flows through the electrothermal conversion element. A so-called thermal method may be employed in which the ink is discharged by causing the ink to generate heat and causing the ink to foam by the generated heat.
The inkjet head that can be used in the present invention may be an edge shooter system in which the shape from the ink flow path to the ejection port is linear, or a side shooter system in which the direction of the ink flow path and the direction of the ejection port are different. It may be.

FIG. 3 is a schematic view showing an example of an edge shooter type print head. The recording (printing) head of FIG. 3 has a discharge energy generator 7 (electrodes for applying a discharge signal to the discharge energy generator 7 and a protective layer provided on the discharge energy generator 7 as necessary are omitted). And the top plate 3 constituting the cover of the flow path 4 and the wall material 2 constituting the side wall of the flow path 4 and the orifice 5.
In the recording head (printing head) 12 that discharges liquid, recording is performed via an electrode (not shown) in a state where ink is stored in a flow path 4 from a liquid chamber (not shown) in which ink is stored. When a signal is applied to the discharge energy generator 7, the discharge energy generated from the discharge energy generator 7 acts on the ink in the flow path 4 above the discharge energy generator 7 (discharge energy operating portion 14b), and as a result, the ink Are discharged from the orifice 5 as droplets. The ejected ink droplets are attached to a recording material such as paper fed to the front of the orifice 5.
In the edge shooter type recording head as shown in FIG. 3, it is very easy to miniaturize each part with high precision, to make the orifices multi-sized or to be miniaturized, and to have high mass productivity. On the other hand, there is a limit to the response frequency and ink droplet flight speed when ejecting ink droplets.
In addition, bubbles are generated in the ink due to the heat generated by the electrothermal conversion element. The bubbles contract due to a decrease in temperature, and the discharge energy generator 7 is gradually destroyed by an impact when the bubbles disappear in the vicinity of the discharge energy generator 7. Is done. This phenomenon is called a cavitation phenomenon and is remarkable in the edge shooter system. Therefore, the life of the edge shooter type recording head is relatively short.

FIG. 4 is a schematic diagram showing an example of a side shooter type recording head. In FIG. 4, this recording head (printing head) 12 is provided with an orifice 5 in the top plate 3, and the direction of ink flow to the ejection energy operating portion in the flow path 4 and the orifice 5 are indicated by a one-dot chain line 14c. The opening center axis is a right angle.
With such a structure, the energy from the discharge energy generator 7 can be more efficiently converted into the formation of ink droplets and the kinetic energy of the flight, and the meniscus can be quickly restored by supplying ink. This is particularly effective when a heating element is used for the discharge energy generator 7.
In addition, a so-called cavitation phenomenon in which the discharge energy generator 7 is gradually destroyed by an impact when bubbles that are problematic in the edge shooter disappear can be avoided in the case of the side shooter. That is, when bubbles grow in the side shooter and the bubbles reach the orifice 5, the bubbles communicate with the atmosphere, and the bubbles do not contract due to a temperature drop. Therefore, there is an advantage that the life of the recording head is long.

FIG. 5 is a schematic sectional view showing a circuit added to the electrode of the liquid discharge head. A recording head (printing head) 12 for discharging a liquid according to the present invention has two electrodes 106 and 107 inside a high fluid resistance region 105. The two electrodes 106 and 107 may be made of the electrode material itself, or may be a member provided with the electrode material. Since the overall configuration of the recording head 12 is the same as the configuration of FIG. 2, the same parts as those in FIG.
The electrode 106 on the side close to the nozzle 101 is made of low rigidity and can be easily bent according to the flow of the flow path 105. In addition, the electrode 107 on the side close to the common liquid chamber 104 is made highly rigid, and is less likely to be deformed than the electrode 106 even if a flow occurs in the flow path 105. In other words, when the elastic modulus of the electrode 106 is E1, and the elastic modulus of the electrode 107 is E2, E1 <E2 is established.
A circuit as shown in FIG. 5 is added to these electrodes 106 and 107. When the electrode 106 and the electrode 107 are in a non-contact state, the potential of the potential detection unit 108 becomes zero, and the circuit is in a short circuit state. In some cases, the power supply voltage Vd is detected. Accordingly, since a discharge failure nozzle can be detected with a simple configuration, a liquid discharge head having excellent discharge stability can be obtained.
In short, the electrode 106 is deformed by the flow of the liquid so as to approach the electrode 107 and contact (electrically connect) with the electrode 107 when deformed more than a predetermined amount.
Referring to FIG. 2 again, let us consider a case where the nozzle (nozzle hole) 101 is in a normal state. When a driving pulse is applied to the pressure generation source 103 and the internal pressure of the individual liquid chamber 102 increases, a flow is generated from the common liquid chamber 104 to the flow path 105, the individual liquid chamber 102, and the nozzle 101.
However, since the fluid resistance of the nozzle 101 is designed to be lower than the fluid resistance of the flow path 105 as described above, most of the liquid is discharged to the outside through the nozzle 101, and the common liquid chamber 104 is passed through the flow path 105. It is not to return to.

FIG. 6 is a schematic cross-sectional view showing the relationship between the distance between electrodes and the flow direction. FIG. 7 is a schematic cross-sectional view showing the movement of the electrode tip with a graph. 6 and 7, the overall configuration of the recording head 12 is the same as the configuration of FIG. 2, so the same parts as those in FIG.
As shown in FIG. 6, the distance between the electrode 106 and the electrode 107 is d, and the common liquid chamber 104 side is in the positive direction and the nozzle 101 side is in the negative direction. In FIG. 7, in this graph, the horizontal axis represents time, and the vertical axis represents the displacement in the flow direction of the tip of the electrode 106.
The state A in FIG. 7 is a state when the liquid is discharged from the nozzle 101. The pressure generated in the individual liquid chamber 102 flows almost toward the nozzle 101 due to the fluid resistance, and droplets are ejected. On the other hand, although a slight flow is generated in the flow path 105, the electrode 106 and the electrode 107 are not brought into contact with each other.
The state B in FIG. 7 is a refill (filling) state after the liquid is discharged. Since the volume of the discharged liquid moves from the common liquid chamber 104 to the individual liquid chamber 102 via the flow path 105, a negative flow occurs inside the flow path 105. Since the displacement of the electrode 106 at this time is in the opposite direction to the electrode 107, it goes without saying that the electrode 106 and the electrode 107 do not contact each other.

FIG. 8 is a schematic cross-sectional view showing the movement of the electrode tip portion different from the case of FIG. 7 together with a graph. 8, the overall configuration of the recording head 12 is the same as the configuration of FIG. 2, and therefore, the same parts as those in FIG.
Next, consider a case where the nozzle 101 is in a non-ejection state for some reason. This will be described with reference to FIGS. When a drive pulse is applied to the pressure generation source 103 and the internal pressure of the individual liquid chamber 102 increases, the nozzle 101 is in a non-ejection state, so that all of the flow goes to the flow path 105.
The movement of the tip of the electrode 106 at this time is as shown in FIG. In the state of C in FIG. 8, since the nozzle 101 is closed, a considerably large flow is generated in the flow path 105 as compared with the case where the nozzle is in a normal state, and the electrode 106 and the electrode 107 are brought into contact with each other. A potential Vd is generated at 108 (FIG. 5).
This potential generated in the potential detection unit 108 becomes a signal indicating that the nozzle is defective in ejection. Accordingly, since a discharge failure nozzle can be detected with a simple configuration, a liquid discharge head having excellent discharge stability can be obtained.
The state D in FIG. 8 is a state in which the volume of the backflowed liquid is moved from the common liquid chamber 104 to the individual liquid chamber 102 via the flow path 105 when the pressure of the individual liquid chamber 102 returns to the original state. It is. As in the state of FIG. 7B, the displacement of the electrode 106 is in the direction opposite to that of the electrode 107, so that the electrode 106 and the electrode 107 do not contact each other.
It is desirable that the potential detected by the potential detection unit 108 is latched by, for example, a storage element or the like and is always accessible from a CPU (central processing unit) that controls the liquid ejection head 12.
By doing so, when a non-ejection state is detected, it is possible to automatically attempt a return process from firmware or the like. By incorporating the above mechanism into the liquid discharge head, it is possible to detect a discharge failure state in units of one nozzle channel.

FIG. 9 is a schematic cross-sectional view showing the main configuration of the first embodiment of the liquid ejection head according to the present invention. A nozzle (nozzle hole) 101 formed in the nozzle plate 100 communicates with the individual liquid chamber 102, and a piezoelectric element 203 is installed in the individual liquid chamber 202 as a pressure generation source. A drive circuit (not shown) is connected to the piezoelectric element 203 so that an arbitrary drive waveform can be applied.
Between the individual liquid chamber 102 and the common liquid chamber 104 for supplying a liquid to the individual liquid chamber 102, a high fluid resistance region 105 whose channel is intentionally narrowed is formed. This high fluid resistance region 105 allows the driving force from the piezoelectric element 203 to be efficiently used for liquid ejection.
Inside the high fluid resistance region 105, an electrode 106 on the nozzle 101 side and an electrode 107 on the common liquid chamber 104 side are installed. The electrode 106 is attached to a thin resin member, and is easily elastically deformed by the flow of the high fluid resistance region 105. The electrode 107 is formed of a copper plate, and its displacement with respect to the flow is very small.
When the piezoelectric method is used in this way, the piezoelectric (piezo) element can be compressed or released, or the amount of deformation of the piezoelectric element 203 can be adjusted to adjust the drive waveform, thereby varying the magnitude. Ink droplets can be ejected. Therefore, it is advantageous for forming an image with good gradation.

FIG. 10 is a schematic cross-sectional view showing a circuit added to the electrode of the liquid discharge head. A potential detecting unit 108 as shown in FIG. 10 is connected to the electrode 106 and the electrode 107, and the potential Vd can be detected when the electrode 106 and the electrode 107 come into contact with each other.
FIG. 10 shows only the case where the piezoelectric element 203 is installed as a pressure generation source, and is the same as FIG. 5 except that the pressure generation source is the piezoelectric element 203. A description other than necessary is omitted here. As described above, the structure including the electrode 106, the electrode 107, and the potential detection unit 108 is arranged in the depth direction on the paper surface by the number of nozzle channels.
FIG. 11 is a circuit diagram showing the potential control circuit. As described above, the structure including the electrode 106, the electrode 107, and the potential detection unit 108 arranged for the number of nozzle channels is arranged for the number of nozzle channels. Here, the number of nozzle channels is 192.
The detection potentials Vd (0, 1, 2... 190, 192) for the number of 192 channels are put on the internal bus 110 via the control circuit 109 as shown in FIG. From the detection potential Vd, the nozzle down position can be determined by the arithmetic processing by the CPU 111 based on the information from the RAM 113 and other logic circuits 114 according to the processing procedure stored in the ROM 112.
When the recording head 12 that discharges the liquid including the above configuration is formed and the nozzle 101 is intentionally lowered in the operation of the liquid discharging head 12 that is a recording head, the nozzle down position can be accurately detected. It was possible.

FIG. 12 is a schematic cross-sectional view showing the main configuration of the second embodiment of the liquid ejection head according to the present invention. A nozzle (nozzle hole) 101 formed in the nozzle plate 100 communicates with the individual liquid chamber 102, and a heating resistor 103 is installed in the individual liquid chamber 102 as a pressure generation source. A driving circuit (not shown) is connected to the heat generating resistor 103, which generates heat when a voltage is applied, forms bubbles in the individual liquid chamber, and discharges the liquid.
The thermal method using the heating resistor 103 is suitable for manufacturing a multi-nozzle head because it is easy to highly integrate the nozzles 101. Therefore, it is advantageous for printing an image with high resolution at high speed.
The other structure of the second embodiment is substantially the same as the structure of the first embodiment, that is, the high-fluid resistance region 105 has an electrode 106 on the nozzle 101 side and an electrode on the common liquid chamber 104 side. A liquid discharge head was formed to include 107.
When the nozzle 101 was intentionally lowered by operating the liquid discharge head 12 thus formed, it was possible to accurately detect the nozzle down location. Therefore, if this liquid discharge head is mounted on an image forming apparatus such as a printer or plotter, a high-quality image forming apparatus with high stability can be obtained.

It is the schematic which shows the inkjet printing apparatus which can apply the liquid discharge head of this invention. FIG. 2 is a schematic cross-sectional view showing a liquid discharge head according to the present invention. It is the schematic which shows the example of the print head of an edge shooter system. It is a schematic diagram showing an example of a side shooter type recording head. It is a schematic sectional drawing which shows the circuit added to the electrode of the liquid discharge head. It is a schematic sectional drawing which shows the relationship between the distance between electrodes, and a flow direction. It is a schematic sectional drawing which shows the motion of an electrode front-end | tip part with a graph. It is a schematic sectional drawing which shows the motion of the electrode front-end | tip part different from the case of FIG. 7 with a graph. 1 is a schematic cross-sectional view showing a main configuration of a first embodiment of a liquid ejection head according to the present invention. It is a schematic sectional drawing which shows the circuit added to the electrode of the liquid discharge head. It is a circuit diagram which shows an electric potential control circuit. It is a schematic sectional drawing which shows the main structures of 2nd Embodiment of the liquid discharge head by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 12 Liquid discharge head 101 Nozzle (nozzle hole)
102 Individual liquid chamber 103 Pressure generating means 104 Common liquid chamber 105 Liquid supply path (flow path)
106 Electrode member 107 Electrode member 108 Potential detector 109 Control circuit 203 Pressure generating means (piezoelectric element)
303 Pressure generating means (heating resistor)

Claims (9)

A nozzle for discharging liquid, an individual liquid chamber for holding the liquid to be discharged, a pressure generating means for generating energy for discharging the liquid, a common liquid chamber for holding the liquid to be supplied to the individual liquid chamber, and the common liquid In a liquid discharge head having a liquid supply path for supplying a liquid from a chamber to the individual liquid chamber,
There are two electrode members in the flow path of the liquid, and at least one electrode member of the two electrode members is disposed in the liquid supply path, and the discharge state of the nozzle is determined from the potential difference between the two electrode members. A liquid discharge head characterized by detecting the above.   The liquid discharge head according to claim 1, wherein the two electrode members are short-circuited when the nozzle does not discharge. Of the two electrode members, when the elastic modulus of the electrode member arranged on the nozzle side is E1, and the elastic modulus of the electrode member arranged on the liquid supply side is E2,
E1 <E2
The liquid discharge head according to claim 1, wherein the liquid discharge head is a liquid discharge head.   When the nozzle is in a discharge state, the two electrode members are not in contact with each other, while when the nozzle is in a non-discharge state and driving the pressure generating means, the flow in the liquid supply path causes the 4. The liquid discharge head according to claim 1, wherein the nozzle-side electrode member is deformed to cause contact between the two electrode members. 5. When the fluid resistance of the nozzle when the liquid is discharged is R1, and the fluid resistance of the liquid supply path is R2,
R1 <R2
The liquid discharge head according to claim 1, wherein the liquid discharge head is a liquid discharge head.   6. The liquid discharge head according to claim 1, further comprising a defective nozzle detection method for detecting a non-discharge nozzle.   An image forming apparatus for forming an image on a sheet using a liquid, comprising the liquid discharge head according to any one of claims 1 to 6 as a liquid discharge head used for image formation. Image forming apparatus.   The two electrode members of the liquid ejection head are arranged in all the nozzle channels, and the detected potential is sent as a nozzle non-ejection state detection signal to a central processing unit that controls the liquid ejection head, and the nozzle non-ejection 8. The image forming apparatus according to claim 7, wherein the state can be confirmed in units of one nozzle. Nozzle for discharging liquid, individual liquid chamber for holding liquid for discharging, pressure generating means for generating energy for discharging liquid, and common liquid chamber for holding liquid for supplying to individual liquid chamber And a defective nozzle detection method for a liquid discharge head having a liquid supply path for supplying liquid from the common liquid chamber to the individual liquid chambers,
Two electrode members are provided in a path through which the liquid flows, and at least one electrode member of the two electrode members is disposed inside the liquid supply path, and the two electrode members are generated by pressure generated in the individual liquid chamber. A defective nozzle detection method for a liquid discharge head, wherein the nozzle discharge state is detected by deforming at least one of the two and detecting a potential difference between the two electrode members.

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