JP3296942B2 - Nozzle clogging detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting nozzle clogging, and more particularly, to a method for detecting nozzle clogging in a continuous jet type ink jet recording apparatus using an ink jet controlled at a constant pressure or a constant flow rate.

[0002]

2. Description of the Related Art In a conventional continuous jet type ink jet recording apparatus, a piston drive type ink pump is used to pressurize ink. The control of the ink pump is classified into a constant pressure control type in which the discharge pressure is controlled to be always constant, and a constant flow rate control type in which the discharge flow rate is controlled so as to be constantly maintained. Is K
ent Blade, "The three-colo
rink jet plotter, a new d
device for the presentatio
no of geophysical data ", Re
port 1/182, Dep. Electr.
Meas. , Lund Inst. Tech. , P.
70-83, JP-A-4-294155, Japanese Patent Application No. 6
No. 111567.

[0003] By the way, in the ink jet recording technology,
Since most of the nozzles are thin, clogging problems occur. If a nozzle becomes clogged, it must be detected and cleared quickly. In a conventional continuous ejection type ink jet recording apparatus, clogging is detected by the following method.

In the case of the constant pressure control type, the moving speed of the piston is measured under the condition that the discharge pressure of the ink pump (in-cylinder pressure) is controlled to a specified value, and the (piston cross-sectional area) is measured.
The discharge flow rate was calculated from the relationship of × (piston moving speed) = (ink discharge flow rate), and if this value was equal to or less than a predetermined value, it was determined that clogging had occurred. When the piston is driven by a stepping motor and a conversion mechanism that converts a rotary motion into a linear motion, the piston moving speed can be measured indirectly from the step rate of the stepping motor.

In the case of the constant flow control type, the discharge pressure of the ink pump (in-cylinder pressure) is measured while the discharge flow rate of the ink (piston moving speed) is controlled to a specified value. When it became, it was judged that it was clogging.

[0006]

In the conventional continuous jet type ink jet recording apparatus described above, in the case of the constant pressure control type,
There is a problem that it takes time to detect clogging. That is, after the discharge pressure of the ink pump has stabilized, the piston movement speed is measured over a period of several seconds to several tens of seconds while waiting for the transient deformation of an elastic substance such as an ink tube (plastic) to settle. Ink discharge flow rates had to be determined. Also, the settling of the transient deformation could not be detected.

Further, in the case of the constant flow control type, there is a problem that it takes time to set the discharge pressure of the ink pump, and it takes time to determine whether the ink is clogged.

Further, in both the constant pressure control type and the constant flow rate control type, when partial clogging occurs but ink jet control is possible and there is no practical problem, measurement of the discharge pressure or the discharge flow rate is performed. There is a problem that the determination cannot be made only by the above. In this case, actual printing was performed, and it was determined whether or not clogging had occurred based on the image quality of the printed image.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a method for detecting clogging of a nozzle which can measure the charging characteristics of an ink jet and detect whether clogging makes it impossible to control the ink jet. It is in.

Another object of the present invention is to provide a simple nozzle clogging detection method capable of accurately and promptly detecting a nozzle clogging state by measuring the charging characteristics of an ink jet.

[0011]

A method for detecting nozzle clogging according to the present invention comprises a constant pressure control pressurizing step of pressurizing ink at a constant pressure, and a jet forming step of discharging the pressurized ink from the nozzles as ink jet. A charging step of inductively charging the ink-jet with a DC voltage, a current detecting step of detecting the charged charge of the charged ink particles that have been inductively charged as a jet current value, and comparing the detected jet current value with a predetermined specified value. And a clogging determination step of determining clogging when the detected jet current value is less than or less than a specified value.

Further, the method for detecting clogging of a nozzle according to the present invention includes a constant flow control pressurizing step of pressurizing ink so that a discharge flow rate from the nozzle is constant, and discharging the pressurized ink from the nozzle as ink jet. A jet forming step, a charging step of inductively charging the inkjet with a DC voltage, a current detecting step of detecting a charge of the inductively charged charged ink particles as a jet current value, and a detected jet current value set in advance. A clogging determination step of determining that clogging is performed when the detected jet current value is equal to or greater than or equal to the specified value.

Further, the method for detecting clogging of a nozzle according to the present invention includes a pressurizing step of pressurizing the ink by a constant pressure control for pressurizing at a constant pressure or a constant flow rate control for pressurizing the discharge flow rate from the nozzle to be constant. A jet forming step of discharging the pressurized ink from the nozzle as an inkjet, and a charging step of inductively charging the inkjet with a DC voltage,
A deflection step of forming a deflection electric field orthogonal to the jet flight axis; a current detection step of detecting, as a jet current value, the DC voltage and the charge of the charged ink particles induced and charged by the deflection electric field; and a detected jet current. A clogging determination step of comparing the value with a preset specified value and determining that the clogging is performed when the detected jet current value is less than or less than the specified value.

Further, the method for detecting clogging of a nozzle according to the present invention includes a constant flow control pressurizing step of pressurizing ink so that a discharge flow rate from the nozzle is constant, and a method of converting the pressurized ink from the nozzle into an ink jet. A jet forming step for discharging, a deflection step for forming a deflection electric field orthogonal to the jet flight axis, a current detection step for detecting the charge of the charged ink particles inductively charged by the deflection electric field as a jet current value, and Comparing the jet current value with a preset specified value, and determining a clogging when the absolute value of the detected jet current value is equal to or larger than the absolute value of the specified value. And

[0015]

In the nozzle clogging detection method of the present invention, the ink is pressurized at a constant pressure in the constant pressure control pressurizing step, the ink pressurized in the jet forming step is ejected from the nozzle as ink jet, and the ink jet is discharged in the charging step. Inductively charging with a DC voltage, detecting the charged charge of the charged ink particles charged inductively in the current detection step as a jet current value, and comparing the jet current value detected in the clogging determination step with a predetermined specified value. When the detected jet current value is less than or less than a specified value, it is determined that clogging is occurring.

In the method for detecting nozzle clogging of the present invention, the ink is pressurized in the constant flow control pressurizing step so that the discharge flow rate from the nozzle is constant, and the ink pressurized in the jet forming step is supplied to the nozzle. The ink jet is discharged from the ink jet, the ink jet is charged by a direct current voltage in the charging step, and the charged charge of the charged ink particles charged in the current detecting step is detected as a jet current value, and the jet current detected in the clogging determination step is detected. The value is compared with a preset specified value, and when the detected jet current value is equal to or larger than the specified value, it is determined that clogging has occurred.

Further, in the method for detecting clogging of a nozzle according to the present invention, the ink is pressurized by a constant pressure control for applying a constant pressure in the pressurizing step or a constant flow rate control for applying a pressure so that the discharge flow rate from the nozzle is constant. The ink pressurized in the jet forming process is ejected from a nozzle as an ink jet, and the ink jet is inductively charged with a DC voltage in a charging process, a deflection electric field orthogonal to a jet flight axis is formed in a deflection process, and the DC voltage is detected in a current detection process. And detecting the charged charge of the charged ink particles induced by the deflection electric field as a jet current value, comparing the jet current value detected in the clogging determination process with a predetermined value, and detecting the detected jet current value. Is determined to be clogged when is less than or less than a specified value.

Further, in the nozzle clogging detection method of the present invention, the ink is pressurized in the constant flow control pressurizing step so that the discharge flow rate from the nozzle is constant, and the ink pressurized in the jet forming step is removed. Discharged as ink jet from nozzle, formed deflection electric field perpendicular to jet flight axis in deflection process, detected charge charge of charged ink particles induced by deflection electric field in current detection process as jet current value, and judged clogging The jet current value detected in the process is compared with a preset specified value, and clogging is determined when the absolute value of the detected jet current value is equal to or larger than the absolute value of the specified value.

[0019]

Next, the present invention will be described in detail with reference to the drawings.

FIG. 5 is a main part configuration diagram showing an example of a continuous jet type ink jet recording apparatus to which the nozzle clogging detection method of the present invention is applied. This continuous jet type ink jet recording apparatus includes an ink bottle 1 containing ink, a cylinder 2 for sucking ink from the ink bottle 1, a piston 3 reciprocating in the cylinder 2, and opening and closing the ink bottle 1 and the cylinder 2. A solenoid valve 4 that freely communicates, an ink tube 5 that supplies ink, a nozzle 6 that communicates with the cylinder 2 through the ink tube 5, and has a very small circular orifice, and a pressure sensor 7 that measures the pressure in the cylinder 2. A piston driving mechanism 9 for reciprocating the piston 3 in the cylinder 2, a microprocessor MPU which is a central processing unit of the continuous jet type ink jet recording apparatus, and a command from the microprocessor MPU and an output of the pressure sensor 7 based on the command. A pump controller 13 for controlling the solenoid valve 4 and the piston drive mechanism 9; And a vibrator 15 composed of a piezoelectric vibrator mounted on the nozzle 6, and a circular or slit-shaped opening concentric with the nozzle 6 and corresponding to image data. A control electrode 16 to which a charge control signal for controlling the charging of the ink jet is applied; and a ground electrode 1 disposed behind (to the right in FIG. 5) the control electrode 16 and grounded.
7, a knife edge 18 attached to the ground electrode 17,
A deflecting electrode 19 for generating a deflecting electric field perpendicular to the jet flight axis between the deflecting power source E1 for generating a DC voltage and the ground electrode 17 to deflect the charged ink particles to the ground electrode 17 side.
And the deflection electrode 1 according to a command from the microprocessor MPU.
9, a first switch SW1 for selectively connecting a deflection power supply E1 or a ground level, and an excitation signal P of a predetermined excitation frequency.
CLK, a reference oscillator CG, and an excitation signal PCLK
A vibrator driver VD for driving the vibrator 15 with a pulse width modulator PWM for converting image data into a pulse width corresponding to a density gradation in synchronization with a pixel recording command signal DCLK;
A DC power supply DCS that generates a constant DC voltage or 0 V according to a command from the microprocessor MPU, a high-voltage switch HVS that amplifies the input voltage and applies it to the control electrode 16 as a charging control signal, and a high-voltage switch HVS according to a command from the microprocessor MPU. Second switch SW2 for selectively connecting pulse width modulator PWM or DC power supply DCS to switch HVS
And a conductive particle catcher 20 disposed behind the knife edge 18 and insulated from the others to detect the charge (jet current I _j ) carried by the ink jet.
When, it is connected to one end to the conductive particles catcher 20 and the shield line 21 leading to the jet current I _j, jet current value I
The main part is composed of a current detector ID for detecting _j and an A / D converter ADC for converting the output of the current detector ID into digital data.

The cylinder 2 and the piston 3 form an ink pump. The volume of the cylinder 2 for one stroke of the piston 3 is larger than the capacity for discharging one print of ink.

Although not specifically shown, the pump control device 13 has a built-in nonvolatile random access memory (hereinafter simply referred to as a memory) in which stored contents are not lost even when the power is turned off.

The conductive particle catcher 20 is disposed in a region not related to recording (hereinafter, referred to as a home position) in the continuous jet type ink jet recording apparatus.
It also serves as a detection electrode (for details, see Japanese Unexamined Patent Application Publication No.
No. 46036).

The current detector 15 is composed of an integrating circuit. For example, the integration time is 2 × 10 ⁴ times or more of the particle formation period, that is, 2 × 10 ⁴ or more electric charges of the ink particles are integrated. A typical value of the particleization period of the inkjet to which the present invention is applied is 1
Since it is 0 ^-6 seconds, the minimum time required for one integration is 2 ×
This is on the order of 10 ^-2 seconds (for details of the integration circuit, see Japanese Patent Application Laid-Open No. H5-246036). A
The jet current value I _j converted into digital data by the / D converter ADC is transmitted to the microprocessor MPU via the data bus.

FIG. 6 is a view showing a state in which the ink jet discharged from the nozzle 6 is divided into ink particles by the surface tension of the ink and the excitation of the vibrator 15 mounted on the nozzle 6. Here, assuming that a jet radius is a and a jet flow velocity is v _j , a distance (hereinafter, referred to as a particleization length) L _j from a nozzle orifice to a point at which ink particles are split (hereinafter, referred to as a split point) is L _j. = K ₁ v _j ln (K
Represented by ₂ a) (C.A.Bruce, "Depen
Dense of Ink Jet Dynamics
on Fluid Characteristic
s ", IBM J. Res. Develop. vol.
20, no. 3, pp258-270, 1976. reference). Here, K ₁ is a constant related to such ink physical property values, K ₂ is a constant related like the excitation conditions.

Now, assuming that the nozzle 6 is partially clogged and the orifice diameter is reduced, the jet radius a
Becomes smaller, and the particleization length _Lj is changed from the normal ink jet state shown in FIG. 7A to the state shown in FIG.
It changes as shown in FIG. FIG. 7B shows that in the case of the constant-pressure control mode, the jet radius a and the jet flow velocity v _j become smaller, so that the particleization length L _j becomes shorter. FIG. 7C shows that in the case of the constant flow rate control mode, the jet radius a becomes smaller, but the jet velocity v _j becomes larger, so that the particle length L _j becomes longer (the jet radius a is logarithmic). And the jet flow velocity v _j is inversely proportional to the square of the jet radius a).

FIG. 8 is a diagram showing the principle of charging of ink particles. The capacitance between the ink particles immediately before splitting from the inkjet (hereinafter referred to as split ink particles) and the control electrode 16 is C _s , the charging control voltage of the control electrode 16 is φ _s , and the split ink particles and the deflection electrode 19 are C ₁ a capacitance between the electrostatic capacitance C _d, the deflection voltage phi _d of the deflection electrode 19, and the division ink particles and the preceding charged ink between,
C ₂ ,..., The potentials of the previously charged ink particles are φ ₁ , φ ₂ ,.
Then, the charge q induced by the split ink particles is
_{q = C s φ s + C} d φ d + (C 1 φ 1 + C 2 φ 2 + ...)
Becomes Here, in the nozzle clogging detection method of the present embodiment, only the variation of the charge q is important, and the third term on the right side can be regarded as almost a constant. it can be expressed as _{q = C s φ s + C} d φ d.

In an actual continuous jet type ink jet recording apparatus, it is desirable that the breaking point of the ink particles is arranged near the entrance inside the control electrode 16. Because if the division point is in front of the entrance of the control electrode 16, the electrostatic capacitance C _s is reduced charging efficiency is remarkably lowered. In addition, the control electrode 16
Approaching the exit, the shielding effect of the control electrode 16 decreases,
Division point so affected deflection electric field E _d by the electrostatic capacitance C _d.

Now, it is assumed that the split point shown in FIG. 8 is a normal position. As shown in FIG. 7A, the nozzle 6 is clogged.
If the particleization length _Lj changes from the normal state shown in FIG. 7B as shown in FIGS. 7B and 7C, C _s , C _d ,
_{q s = C s φ s,} q d = C d φ d is changed as shown in the graph of FIG. 8, charge q changes as follows.

In the case of the constant pressure control mode, the split point comes before the entrance of the control electrode 16, so that the charge q is rapidly reduced.

In the case of the constant flow control mode, the induced charge q _s slightly increases in the case of very slight clogging,
In most cases, the induced charge q _d becomes dominant, and the charged charge q rapidly decreases.

Therefore, the clogged state of the nozzle 6 can be detected by examining the change in the charge q. Further, the induced charge q _d and the induced charge q _s, since the voltage phi _s or phi _d can be measured independently by 0, it is possible more accurate measurement.

FIG. 1 is a flowchart showing a processing procedure of the nozzle clogging detection method according to the first embodiment of the present invention for detecting clogging of the nozzle 6 in the constant pressure control mode. The processing procedure of the nozzle clogging detection method of this embodiment is as follows.
First switch grounding step S11, second switch DC power supply connection step S12, DC power supply output voltage setting step S13
And an ink pump constant pressure control mode start-up step S14;
It comprises a jet current value measurement step S15, a jet current value comparison step S16, a clogging determination step S17, and a normality determination step S18.

Next, processing of the nozzle clogging detection method according to the first embodiment will be described.

Here, it is assumed that a normal jet current value I _j1 is measured in advance at the start of use of the continuous jet type ink jet recording apparatus and at the time of nozzle replacement, and is stored in the memory of the microprocessor MPU. Further, it is assumed that the clogging margin α indicating the allowable variation ratio of the jet current value I _{j with} respect to the normal jet current value I _j1 is empirically determined and stored in the memory of the microprocessor MPU. The method of measuring the normal jet current value I _{j1 is the same as} the method of measuring the jet current value I _j described below, except that the nozzle 6 is a new nozzle 6 that is not clogged.

When detecting the clogging of the nozzle 6, the microprocessor MPU connects the first switch SW1 to the ground side at the home position where the print head (carriage) mounting the nozzle 6 faces the conductive particle catcher 20. To turn off the deflection electric field (step S11), and connect the second switch SW2 to the DC power supply DCS side (step S1).
2), the output voltage of the DC power supply DCS is set to φ _s (step S
13) (phi _s voltage, to charge the ink jet example when printing).

Next, the microprocessor MPU instructs the pump control device 13 to start up the ink pump in a constant pressure control mode of a specified pressure. Then, the pump control device 13 closes the electromagnetic valve 4 and drives the piston drive mechanism 9 while referring to the output of the pressure sensor 7,
The ink pump is started up and stabilized in the constant pressure control mode (step S14).

Then, the ink in the cylinder 2 is ejected from the nozzle 6 through the ink tube 5 as ink jet. Jet ejected from the nozzle 6 is split into ink droplets in synchronism with the excitation by the transducer 15, a constant DC voltage phi _s charge control applied to the control electrode 16 via a high voltage switch HVS from the DC power supply DCS induced charged at a constant charge q = C _s φ _s by the signal, the ground electrodes 17, deflection electrodes 19 and the knife edge 1
8 and are captured by the conductive particle catcher 20.

The current detector ID is a charge q = C _s φ _s of the captured ink particles to the conductive particles catcher 20 is measured as a jet current I _j (step S15). A
/ D converter ADC converts the jet current I _j measured by the current detector ID in the digital data, and outputs to the data bus. The microprocessor MPU takes in a jet current I _j on the data bus is stored into the memory.

Subsequently, the microprocessor MPU determines in advance a value obtained by adding an empirically determined clogging margin α (for example, α = 0.1I _j1 ) to the measured jet current value I _j , and Normal measured jet current value I _j1
Comparing the magnitude of the (step S16), the clogging in the case of a constant pressure control mode occurs granulated length L _j becomes smaller (see FIG. 7 (b)), charge q = C _s φ _s, That is, since the jet current value I _j decreases (see FIG. 8), I _j
When + α <I _j1 , it is determined that clogging has occurred (step S17).
_{When j} + α ≧ I _j1 , it is determined to be normal (step S18).
It should be _noted that clogging is determined when I _j + α ≦ I _j1 , and I _j +
When α> I _j1 , it may be determined to be normal.

FIG. 2 is a flowchart showing a processing procedure of the nozzle clogging detection method according to the second embodiment of the present invention for detecting clogging of the nozzle 6 in the constant flow rate control mode. The processing procedure of the nozzle clogging detection method of this embodiment includes a first switch grounding step S21, a second switch DC power supply connection step S22, and a DC power supply output voltage setting step S2.
3, and ink pump constant flow rate control mode start-up step S24
, A jet current value measurement step S25, a jet current value comparison step S26, a clogging determination step S27, and a normality determination step S28.

Next, the processing of the method for detecting nozzle clogging according to the second embodiment will be described.

Here, as in the case of the first embodiment, a normal jet current value I _j2 is measured in advance at the start of use of the continuous jet type ink jet recording apparatus and at the time of replacement of the nozzle 6, and this is measured by the microprocessor MPU. Is stored in the memory. Further, it is assumed that the clogging margin β indicating the permissible variation ratio of the jet current value I _{j with} respect to the normal jet current value I _j2 is empirically determined and stored in the memory of the microprocessor MPU.
The method of measuring the normal jet current value I _j2 is based on the nozzle 6
There simply because the new nozzles 6 without causing clogging, is the same as the method for measuring the jet current I _j to be described later.

At the home position where the print head (carriage) mounting the nozzle 6 faces the conductive particle catcher 20 when the nozzle 6 is clogged, the microprocessor MPU operates according to the first embodiment shown in FIG. The same processing as steps S11 to S13 in the nozzle clogging detection method is performed (steps S21 to S23).

Next, the microprocessor MPU instructs the pump control device 13 to start up the ink pump in the constant flow rate control mode at the specified flow rate. Then, the pump controller 13 closes the electromagnetic valve 4 and starts and stabilizes the ink pump in the constant flow mode in which the piston 3 is moved at a constant speed by the piston driving mechanism 9 (step S2).
4).

Then, the ink in the cylinder 2 is ejected from the nozzle 6 through the ink tube 5 as ink jet. Jet ejected from the nozzle 6 is split into ink droplets in synchronism with the excitation by the transducer 15, a constant DC voltage phi _s charge control applied to the control electrode 16 via a high voltage switch HVS from the DC power supply DCS induced charged at a constant charge q = C _s φ _s by the signal, the ground electrodes 17, deflection electrodes 19 and the knife edge 1
8 and are captured by the conductive particle catcher 20.

The current detector ID is a charge q = C _s φ _s of the ink particles captured by the conductive particles catcher 20 is measured as a jet current I _j (step S25). A
/ D converter ADC converts the jet current I _j measured by the current detector ID in the digital data, and outputs to the data bus. The microprocessor MPU takes in a jet current I _j on the data bus is stored into the memory.

Subsequently, the microprocessor MPU determines in advance a value obtained by subtracting an empirically determined clogging margin β (for example, β = 0.1I _j2 ) from the measured jet current value I _j and for each nozzle 6. Normal measured jet current value I
comparing the magnitude of the _j2 (step S26), the particles of the length L _j When clogging occurs in the case of a constant flow rate control mode is increased (see FIG. 7 (c)), charge q = C _s phi _s , ie, the jet current value I _j increases (see FIG. 8),
_{When j−} β> I _j2 , it is determined that clogging has occurred (step S27),
If I _j −β ≦ I _j2 , it is determined to be normal (step S2
8). It should be noted that clogging is determined when I _j −β ≧ I _j2 ,
When I _j −β <I _j2 , it may be determined to be normal.

FIG. 3 is a flowchart showing a processing procedure of a nozzle clogging detecting method according to a third embodiment of the present invention which can detect clogging of the nozzle 6 in both the constant pressure control mode and the constant flow rate control mode. It is. The processing procedure of the nozzle clogging detection method of the present embodiment includes a first switch deflection power supply connection step S31, a second switch DC power supply connection step S32, a DC power supply output voltage setting step S33, an ink pump constant pressure control mode or Constant flow control mode start-up step S34, jet current value measurement step S35, jet current value comparison step S36, and clogging determination step S37.
And a normality determination step S38.

Next, the processing of the method for detecting nozzle clogging according to the third embodiment will be described.

Here, as in the first and second embodiments, a normal jet current value I _j3 is measured at the start of use of the continuous jet type ink jet recording apparatus and at the time of replacement of the nozzle 6. , Are stored in the memory of the microprocessor MPU. It is also _assumed that the clogging margin γ indicating the allowable variation ratio of the jet current value I _{j with} respect to the normal jet current value I _j3 is empirically determined and stored in the memory of the microprocessor MPU. The method of measuring the normal jet current value I _{j3 is the same as} the method of measuring the jet current value I _j described below, _except that the nozzle 6 is a new nozzle 6 in which no clogging occurs.

In the nozzle clogging detection method of the third embodiment, the deflection power supply E1 is connected to the deflection electrode 19 (deflecting the charged ink particles in a direction perpendicular to the jet flight axis), and the nozzle 6 is clogged. Therefore, when the clogging of the nozzle 6 is detected, the charged ink particles can also pass through the knife edge 18 at the home position where the print head (carriage) mounting the nozzle 6 faces the conductive particle catcher 20. As described above, the axis of the nozzle 6 is adjusted upward in advance.

From this state, the microprocessor MPU
Connects the first switch SW1 to the deflection power supply E1 side to turn on the deflection voltage φ _d (step S31), and the first switch SW1 shown in FIG.
Steps S12 and S12 of the nozzle clogging detection method of the embodiment
The same processing as in step 13 is performed (steps S32 and S33).

Next, the microprocessor MPU instructs the pump controller 13 to start up the ink pump in the constant pressure control mode or the constant flow control mode. Then, the pump controller 13 closes the electromagnetic valve 4 and starts up and stabilizes the ink pump in the constant pressure control mode or the constant flow rate control mode by the piston drive mechanism 9 while referring to the output of the pressure sensor 7 (step S34). .

Then, the ink in the cylinder 2 is ejected from the nozzle 6 through the ink tube 5 as ink jet. Jet ejected from the nozzle 6 is split into ink particles, which is applied to the charging control signal and the deflection electrodes 19 of the constant DC voltage phi _s applied to the control electrode 16 via a high voltage switch HVS from the DC power supply DCS Charge q = C _s φ _s by constant deflection voltage φ _d
+ C _d φ _d is induced and passes through the knife edge 18 and is captured by the conductive particle catcher 20.

The current detector ID has a charge q = C _s φ _s + of the ink particles captured by the conductive particle catcher 20.
C _d φ _d is detected as a jet current value I _j (step S
35). A / D converter ADC converts the jet current I _j detected by the current detector ID in the digital data,
Output to data bus. The microprocessor MPU,
Incorporating a jet current I _j on the data bus is stored into the memory.

Subsequently, the microprocessor MPU measures in advance a value _obtained by adding an empirically determined clogging margin γ (for example, γ = 0.1 I _j3 ) to the jet current value I _j and each nozzle 6. The magnitude is compared with the normal jet current value I _j3 that has been set (step S36). In the case of the constant pressure control mode, if the clogging occurs, the particle length L _j becomes small (FIG. 7B).
), The induced charge q _s = C _s φ _s decreases and the jet current value I _j decreases (see FIG. 8). In the case of the constant flow rate control mode, when the clogging occurs, the particle length L _j is reduced. As shown in FIG. 7 (c), the induced charge q _s = C _s φ _s gradually increases, but the induced charge q _d = C _d φ _d sharply decreases. As a result, the jet current value I _j decreases. (See FIG. 8), it is determined that clogging occurs when I _j + γ <I _j3 (step S
37), when I _j + γ ≧ I _j3 , it is determined to be normal (step S38). Note that clogging may be determined when I _j + γ ≦ I _j3 , and normal may be determined when I _j + γ> I _j3 .

FIG. 4 is a flowchart showing a processing procedure of a nozzle clogging detection method according to a fourth embodiment of the present invention for detecting clogging of the nozzle 6 in the constant flow rate control mode. The processing procedure of the nozzle clogging detection method of the present embodiment includes a first switch deflection power supply connection step S41, a second switch DC power supply connection step S42, a DC power supply output voltage setting step S43, an ink pump constant flow rate control mode. Start-up step S44, jet current value measurement step S45, jet current value absolute value comparison step S46, clogging determination step S4
7 and a normality determination step S48.

Next, the processing of the nozzle clogging detection method according to the fourth embodiment will be described.

[0060] In the nozzle clogging detection method of the present embodiment, without applying the charge control signal to the control electrode 16, so measuring the jet current I _j by induction charging of the deflection electric field E _d, continuous Normal jet current value I at the start of use of the ejection type ink jet recording apparatus and at the time of replacing the nozzle 6
_j is measured as the permissible induced current value I _d0 , which is stored in the memory of the microprocessor MPU. Measurement method itself allowable induced current I _d0 is simply because the new nozzle 6 nozzle 6 is not caused clogging, is the same as the method for measuring the jet current I _j to be described later.

At the home position where the print head (carriage) on which the nozzle 6 is mounted faces the conductive particle catcher 20 when the nozzle 6 is clogged, the microprocessor MPU operates according to the third embodiment shown in FIG. After performing the same processing as steps S31 and S32 of the nozzle clogging detection method (steps S41 and S42), the output voltage φ _s of the DC power supply DCS is set to 0 V (φ _s = 0).
(Step S43).

Next, the microprocessor MPU instructs the pump controller 13 to start the ink pump in the constant flow control mode. Then, the pump control device 13
Closes the electromagnetic valve 4 and starts up and stabilizes the ink pump in the constant flow rate control mode by the piston drive mechanism 9 while referring to the output of the pressure sensor 7 (step S44).

Then, the ink in the cylinder 2 is ejected from the nozzle 6 through the ink tube 5 as ink jet. Jet ejected from the nozzle 6 is split into ink droplets, through the control electrode 16, the ground electrode 17 by the deflection voltage phi _d of the deflection power source E1, charged with the generated deflection field E _d between the deflection electrodes 19 Charge q = C _d
Inductively charged to φ _d , passes through the knife edge 18 and is captured by the conductive particle catcher 20.

The current detector ID measures the charge q = C _d φ _d of the ink particles captured by the conductive particle catcher 20 as the jet current value I _j (step S45). A
/ D converter ADC converts the jet current I _j measured by the current detector ID in the digital data, and outputs to the data bus. The microprocessor MPU takes in a jet current I _j on the data bus is stored into the memory.

[0065] Subsequently, the microprocessor MPU, the absolute value of the jet current I _j | I _j | a previously measured absolute value of the allowable induced current I _d0 by the deflection electric field E _d | I _d0 |
(Step S46). Incidentally, the allowable induced current I _d0 is, for example, about -0.1I _j0 (I _j0
The jet current value measured by the induction charging due only normal charge control voltage phi _s). The microprocessor MPU, if the constant flow control mode clogging occurs when particles of length L _j is increased (see FIG. 7 (c)), | q d | = | C
_d φ _d | increases and the absolute value of the jet current I _j | I _j |
Is increased (see FIG. 8), it is determined that clogging occurs when | I _j |> | I _d0 | (step S47), and | I _j | ≦ | I _d0
It is determined to be normal when | is satisfied (step S48). | I
_j | ≧ | I _d0 | is determined to be clogging, and | I _j | <|
It may be determined to be normal when I _d0 |.

[0066]

As described above, according to the present invention, the change in the jet current caused by the particleization length that changes depending on the clogging state is measured, so that the clogging state makes it impossible to control the ink jet. It is possible to directly determine whether or not the clogging is performed, and there is an effect that fine clogging can be determined.

Further, it is possible to determine the clogged state of the nozzle only from the charging characteristics of the ink jet, and there is an effect that high-speed and accurate clogging determination can be realized at low cost.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a processing procedure of a nozzle clogging detection method according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a processing procedure of a nozzle clogging detection method according to a second embodiment of the present invention.

FIG. 3 is a flowchart showing a processing procedure of a nozzle clogging detection method according to a third embodiment of the present invention.

FIG. 4 is a flowchart showing a processing procedure of a nozzle clogging detection method according to a fourth embodiment of the present invention.

FIG. 5 is a main part configuration diagram showing an example of a continuous ejection type ink jet recording apparatus to which the nozzle clogging detection method of the present invention is applied.

6 is a diagram illustrating a relationship between a jet radius, a jet flow velocity, and a particleization length in the continuous jet type ink jet recording apparatus of FIG. 5;

FIG. 7 is a diagram illustrating a particleization length of an inkjet in the continuous ejection type inkjet recording apparatus of FIG. 5,
(A) shows the case where the graining length is normal, (b) shows the case where the graining length is short, and (c) shows the case where the graining length is long.

FIG. 8 is a diagram for explaining the principle of the nozzle clogging detection method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Ink bottle 2 Cylinder 3 Piston 4 Solenoid valve 5 Ink tube 6 Nozzle 7 Pressure sensor 9 Piston drive mechanism 13 Pump control device 14 Ink electrode 15 Vibrator 16 Control electrode 17 Ground electrode 18 Knife edge 19 Deflection electrode 20 Conductive particle catcher 21 Shield line ADC A / D converter CG Reference oscillator DCLK Pixel recording command signal DCS DC power supply E1 Deflection power supply HVS High voltage switch ID Current detector MPU Microprocessor PCLK Excitation signal PWM Pulse width modulator SW1 First switch SW2 Second switch VD Vibration Child driver S11, S21, S31, S41 First switch grounding step S12, S22, S32, S42 Second switch DC power supply connection step S13, S23, S33, S43 DC power supply output voltage setting step S1 Ink pump constant pressure control mode start-up step S15, S25, S35, S45 Jet current value measurement step S16, S26, S36, S46 Jet current value comparison step S17, S27, S37, S47 Clogging determination step S18, S28, S38, S48 Normal determination step S24, S44 Ink pump constant flow rate control mode start-up step S34 Ink pump constant pressure control mode or constant flow rate control mode start-up step

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B41J 2/175 B41J 2/01 B41J 2/02

Claims (4)

(57) [Claims] 1. A constant-pressure control pressurizing step of pressurizing ink at a constant pressure, a jet forming step of discharging the pressurized ink from a nozzle as an ink jet, a charging step of inductively charging the ink jet with a DC voltage, an induction charging. A current detection step of detecting the charged charges of the charged ink particles as a jet current value, and comparing the detected jet current value with a preset specified value, and the detected jet current value is less than or less than a specified value. A clogging determination step of sometimes determining clogging. 2. A constant flow rate control pressurizing step for pressurizing the ink so that the discharge flow rate from the nozzle is constant, a jet forming step for discharging the pressurized ink from the nozzle as an ink jet, A charging step of inductively charging, a current detecting step of detecting the charged charge of the charged ink particles as a jet current value, and a jet detected by comparing the detected jet current value with a preset specified value. A clogging determination step of determining clogging when the current value is equal to or greater than a specified value. 3. A pressurizing step of pressurizing the ink by a constant pressure control for pressurizing at a constant pressure or a constant flow rate control for pressurizing the discharge flow rate from the nozzle to be constant, and discharging the pressurized ink from the nozzle as ink jet. A charging step for inductively charging the inkjet with a DC voltage; a deflecting step for forming a deflection electric field orthogonal to a jet flight axis; and charging of the charged ink particles induced and charged with the DC voltage and the deflection electric field. A current detecting step of detecting electric charge as a jet current value, and comparing the detected jet current value with a preset specified value, and determining that the clogging is performed when the detected jet current value is less than or less than a specified value. A method for detecting clogging of a nozzle, comprising a clogging determination step. 4. A constant flow rate control pressurizing step for pressurizing the ink so that the discharge flow rate from the nozzle is constant, a jet forming step for discharging the pressurized ink from the nozzle as ink jet, and a direction perpendicular to the jet flight axis. Deflecting step of forming a deflecting electric field, a current detecting step of detecting a charge of the charged ink particles induced by the deflecting electric field as a jet current value, and comparing the detected jet current value with a preset specified value. A clogging determination step of determining clogging when the detected absolute value of the jet current value is greater than or equal to the absolute value of the specified value.