JPS58104760A - Deflection controlling ink jet recorder - Google Patents

Abstract

PURPOSE:To improve the instability of detection due to the ink fouling of a tabular charge detecting electrode, and to shorten the time of charge detection by varying the set value of a deflection-quantity setting means while using the detecting signals of a charge detecting circuit as reference. CONSTITUTION:A tabular charge detecting electrode 13 is adjoined to a predetermined charge ink grain deflection locus, and connected to the ground as reference potential through a resistor R and to the charge detecting circuit 23. The application and interruption of charging voltage are repeated for a period TD longer than an ink-grain forming period in the detection of deflection, pulsating voltage, one period thereof is TD, appears in the resistor R together with the floating capacity of the electrode 13, the voltage is extracted by means of a filter HPF, integrated and compared with prescribed value, and collision is discriminated. Accordingly, even when a gutter and recovery ink are conducted due to ink fouling, discharge currents flowing through the resistor does not lower largely when the value of the resistor R is made sufficiently lower than ink, and the impossibility of detection is prevented.

Description

Detailed Description of the Invention The present invention jets pressurized ink from a nozzle, applies vibration to the jetted ink to form ink particles regularly, and selectively charges the ink particles based on an image signal when the ink particles are generated. The present invention relates to deflection-controlled inkjet recording in which an electric field is formed, ink particles are charged by the electric field, and the charged ink particles are deflected by a deflection electric field, and particularly relates to deflection control for causing the ink particles to fly in a predetermined deflection trajectory.

In this type of inkjet recording, the distance from the ink jetting nozzle to the recording paper is relatively long, and therefore the ink pressure remains constant even though the ink particles ejected from the nozzle and turned into particles are affected by a charging electric field and a deflection electric field. It is set high so that it traces a stable flight trajectory to the recording paper and reaches t. In addition, in order to regularly generate ink particles of a predetermined particle size and cause them to accurately follow a predetermined deflection trajectory, ink viscosity, ink pressure, vibration pressure, charge I, deflection electric field, etc. must be stabilized. and must be precisely controlled.

For this reason, US Pat. No. 3,787,882 proposes controlling the ink pressure, temperature, and ink flight speed. However, in the control of the deflection position of ink particles, that is, the printing point control, for high-density recording such as 4 dots/dot or 8 dots/dot, deflection control must be performed extremely finely, and it is necessary to control the deflection only by ink pressure. Control still lacks stability, precision and responsiveness. Therefore, the present inventor proposed to perform deflection control by adjusting the charging voltage level and the deflection voltage level (Japanese Patent Application No. 140798/1983, Japanese Patent Application No. 141836/1983).
No. 55-18914, etc.). In this voltage level adjustment, while the deflection position of the ink droplet is out of a predetermined position, the charging voltage level and/or the deflection voltage level is shifted step by step in the direction of moving the ink droplet to a predetermined position.
The deflection position of the ink droplets is detected each time the voltage level is changed. In addition to this, there is also a method of adjusting the excitation voltage, ink temperature, or ink pressure. ' In the above patent application, a charge detection electrode plate and an integrating circuit are used to integrate the charge when a charged ink droplet comes into contact with the charge detection electrode plate, and the integrated voltage while a predetermined number of ink droplets arrive is a predetermined value. If this is the case, it is determined that the charged ink particles are hitting the charge detection electrode plate. The charge detection electrode plate is installed in a gutter that captures non-printing ink particles during recording control, or (1) in a separately provided gutter that captures ink particles that come off the gutter when the ink jet head is in the home position. Ru. Since the electric charge held by one reaching particle is extremely small, approximately 0.8 x 10-12 chromium, consideration is given to the insulation of the charge detection electrode plate. However, ink droplets caused by the collision of ink particles with the charge detection electrode plate and the gutter contaminate the insulator surface supporting the gutter, and this contamination causes leakage between the gutter and the collected ink, making the capacitor voltage of the integrating circuit unstable. However, there is a problem that charge detection becomes unstable. In particular, when the dirt is severe, it is determined that the battery is not charged even if it is properly charged.

To solve this problem, it is necessary to keep a part of the rattle clean at all times, which is difficult to manage. Historically, in this charge detection, frictional electrification of the ink when it is ejected from the nozzle and generation of electric charge when the ink particles collide with the gutter have been used to determine whether the ink particles are charged or uncharged due to the voltage of the charging electrode. The charge detection signal due to the uncharged charge is charged to the capacitor as a DC bias, and S
//N is low, it is necessary to increase the number of charged ink particles in order to prevent false detection, and it takes a long time to set an appropriate deflection amount.

The first object of the present invention is to improve the quality of hair detection due to ink stains in deflection detection using a plate-shaped charged detection electrode.
The second purpose is to shorten the charge detection time, and the third purpose is to stably set the deflection amount to a predetermined set value.

In order to achieve the above object, in the present invention, a plate-shaped charge detection electrode is arranged adjacent to a predetermined charged ink particle deflection locus, and is connected to ground, which is a reference potential, through a resistor or other resistor. It is also connected to the charge detection circuit. The deflection detection method charges a predetermined number m of generated ink particles by repeatedly applying and cutting off a charging voltage to the charging electrode at a predetermined period TD that is longer than the ink particle generation period (however, one or several particles may be charged). (including skip charging), and forms a charging pattern in which the next n items are uncharged. By this, and when a resistor and, if necessary, a parallel capacitor is connected, by appropriately setting the electrical quantity of the capacitor, when a charged ink particle is colliding with a plate-shaped charge detection electrode, Along with the stray capacitance of the plate-shaped charge detection electrode, a pulsating voltage with one period equal to the previous period TD appears on the resistor. When charged ink particles are not colliding, no pulsating voltage appears and a DC constant voltage ( ground level) or a slight reverse polarity pulsating voltage due to electrostatic induction. The charge detection circuit extracts only the pulsating voltage component through a filter, integrates it, and compares the integrated voltage with a predetermined value to determine whether or not the charged ink particles are colliding with the detection electrode. Discern. In this way, the discharge current of the resistor connected to the plate-shaped charge detection electrode is detected in an alternating current manner, so even if there is ink stain and conduction occurs between the gutter and the collected ink, the resistance value of the resistor can be detected by the ink. By setting the resistance value to a value sufficiently lower than the resistance value of , the discharge current flowing through the resistor will not be significantly reduced and will not become undetectable. In a preferred embodiment of the present invention, the deflection amount adjustment is linked to the deflection detection, and the deflection amount is determined to an appropriate value by particularly linked charging voltage level adjustment.

FIG. 1 shows the main mechanical elements of one embodiment of the invention, and FIG. 2 shows the main electrical elements. First, refer to FIG. In FIG. 1, ink in an ink tank 1 is sucked by a pump 3 through a filter 2 and is pumped to an accumulator 4. Pressure vibrations caused by suction and discharge of the pump 3 are absorbed in the accumulator 4.

For constant pressure ink, use a solenoid valve 5. The ink is supplied to the ink jet head 8 through the filter 6 and heater 7.

In the head 8, constant frequency pressure vibrations are applied to the ink by constant frequency excitation of an electrostrictive vibrator. As a result, the ink ejected from the nozzle of the ink ejection notch 8 separates into ink particles at a predetermined distance from the nozzle. A charging electrode 9 is disposed at this separation position, and when a charging voltage is applied to the electrode 9 at the time of separation, the ink particles are charged to a polarity opposite to the polarity of the charging voltage. The charged ink particles are transferred to the deflection electrode 10. ．． When the head is in the recording position, it collides with the recording paper 26, and when the head is in the home position, it heads toward the gutter 12. Uncharged ink particles are directed toward the gutter 11 both when the head is in the recording position and when the head is in the home position. In other words,
A filter 6 through a gutter 11, surrounded by dash-dot lines, are mounted on the scanning carriage, with gutter 12 positioned to capture charged ink particles when the carriage is in the home position. When the carriage is at the home position, the flight line of the ejected ink particles is on the recording paper 2.
Off the edge of 6, charged ink particles are captured in gutter 12. The ink in the gutter 11 is sucked by the pump 27' and returned to the ink tank 1, and the ink in the gutter 12 returns to the ink tank 1 by its own weight. When the ink injection stops, first the pump 3 and the heater 7 are deenergized, then the solenoid of the solenoid valve 5° is deenergized, and then the pump 27 is deenergized. The solenoid valve 5 closes the accumulator 4 due to the deenergization of the renoid.
- to cut off the gap between the filter 6 and the ink tank 1 - the filter 6.
Make the space continuous.

A plate-shaped charge detection electrode 13 is insulated and supported in the gutter 12.
There is. A shield wire 14 is connected to this electrode 13.

An electric circuit shown in FIG. 2 is connected to the terminals shown in FIG. 1 to N. It should be noted that terminals A-N are shown for convenience and that such intermediate terminals are not necessarily required.

FIG. 3 shows the configuration of the charge detection circuit 23 shown in FIG. 2. Referring to FIG. 3, between the core wire of the shield wire 14 and the ground, the electrode 1 is due to ink stains on the inner wall of the gutter 12.
3-ground, a resistance Rcζ1 smaller than that to prevent instability in charge detection due to fluctuations in insulation resistance between
A voltage conversion resistor R having Ω is connected to 00. A charge detection circuit 23 is connected to the core wire of the shielded wire 14 .

This circuit 23 is composed of a high input impedance field-effect transistor FIT, an operational amplifier OPI, a high-pass filter HPF-, an integrator circuit IGR for DC smoothing, and a comparator COM.

FIG. 4 shows the configuration of the phase setting circuit 24, and FIG. 5 shows the input/output timing of each part thereof. Referring also to FIG. 5, a 1.6 MHz clock pulse OP is applied to the phase setting circuit 24, and this is counted by the counter COI. The A bit of each pit A-D (A = 1st to D = 4th) of the count code output of the counter COI is used as a shift activation pulse to the shift register SR of the serial imper 5V Luaud, and the D bit is input. Applied as a signal. As a result, pulses with a pulse width of D whose phase is shifted by A period appear sequentially at the output terminal O of the shift register SR, and one of the pulses is output from the data selector DS as the electrostrictive resonator excitation pulse Vp, and the excitation voltage is outputted from the data selector DS. Generator 19
It is applied to protect.

The output bits of the BSD of the counter COI are applied to the decoder DE, and the output pulses of the first output 0 and the fifth output 4 of the decoder DE are applied to the frequency divider FDI and the T-7 lip-flop FF, respectively.

The Q output of the T-flip-flop FF is applied to the charge voltage generator 20 as a charge timing signal CP. The pulse, which is frequency-divided by the frequency divider FDI and shaped to the output pulse width of the output terminal O of the decoder DE by AN2, is applied to the search charge voltage generator 21 as the phase search charge signal PP. be done.

As shown in FIG. 5, the charge signal pp has 16 consecutive pulses, followed by a pause period of 16 pulses, which is 320 μs.
It is intermittent at the cycle of ec. On the other hand, the printing charge timing signal Cp was continuous. The pulse width is 8 times that of the outside pulse (high level Ill).

In this embodiment, the phase search charge signal (RusPP
The phases of both pulses and impression timing pulses CP are fixed, and the phase of the electrostrictive oscillator excitation pulse vP is: 1:
・111・゛・Todata select: The data is shifted or changed depending on which of the shift register outputs 0 to 7 is output according to the count codes A to C of the counter CO2 in the DS.

In other words, the charging voltage pulse phase is fixed and the ink droplet separation phase is shifted.

Next, phase search will be explained. At the time of phase search, the carriage is placed at the home position, the charging voltage changeover switch SW is closed to the search charging voltage generator 21 side, and the deflection voltage power supply circuit 22 is energized (switched on). In this autumn, a negative constant level charging pulse synchronized with a phase search charging pulse PP with a period of 10μ intermittent at a cycle of 320μsec is applied to the switch S by the search charging voltage generator 21.
A voltage is applied to the charging electrode 9 via W. On the other hand, if the count code of the counter CO2 is "000", the pulse at the output terminal 0 of the shift register SR is applied as the excitation pulse V to the excitation voltage generator 19, and the period and Ink particles are separated in a phase corresponding to the phase (phase with respect to Pp). When the separation of the ink particles is timed with the pulse Pp, the ink particles become positively charged and collide with the electrode 13 of the gutter 12.

In other words, the ink particles separated at the period of the pulse P produce a charging pattern with a period of 32 olSec, in which 16 consecutive particles are negatively charged and the next 16 particles are uncharged, and all the ink particles reach the plate-shaped charge detection electrode 13. collide. Therefore, in this case, the potential of the electrode 13 causes potential fluctuations similar to the charging pattern. However, due to the floating capacitance of the shield line 14 and the time constant of the resistor R, the pace potential of the FET of the charge detection circuit 23 causes a sine wave-like or envelope-like potential fluctuation with a period of 320μ. Such a sine wave voltage is inverted by the FET, further inverted and amplified by the operational amplifier OPI, and then applied to the bypass filter HPF at a positive level. The bypass filter HPF blocks noise with a period of less than 320 μsec. Integrating circuit IGR is 320μsec
Smoothes the periodic sine wave and stabilizes it to a constant DC level. This DC voltage is compared with the reference voltage by the comparator COM. When the DC voltage is higher than the reference voltage, that is, when the ink particles are charged, the output of the comparator COM becomes a low level "0", and the ink particles When COM is uncharged or incompletely charged, the output of comparator COM is a high level "1".

The output of this comparator COM is given to the printing control unit 25 and also to the phase setting circuit 24.
is applied to The printing control unit 25 includes a switch SW.
is closed to the 21 side, and then a search judgment pulse PDK is applied to the ant game ()ANI of the circuit 24 at a cycle of 10 m5ec,
Output P of comparator COM. When K becomes "0" (ink particle charge detected), the output of the PDK every 10 m5ec is stopped, and the process moves to deflection detection/deflection amount setting control (deflection amount adjustment). Therefore, while the output of the comparator COM is "1" (ink is not charged), a pulse is applied to the counter CO21m from the AND gate ANI every lQm5eC, the counter CO2 increases by 1, and the data selector D
The output vP of S changes from the pulse at the output end t of the shift register SR to the pulse at the output end i + 1 (that is, the phase is shifted by one step). The counter CO2 carries out circular counting, and when a pulse from one of the output terminals O to 7 of the shift register SR is applied as VP to the excitation voltage generator 19', the ink particles are charged, and the output of the comparator COM is becomes 1 (month).

After finishing the phase setting, the printing control unit 25 adjusts the amount of deflection. FIG. 6 shows the configuration of the printing charge voltage generating circuit 20, which is related to the adjustment of the amount of deflection. In this embodiment, the circuit 20 receives a pulse P from the unit 25 during print recording.
Charging voltage code S in synchronization with P. C (multiple values corresponding to the number of deflection stages) is switched to the input AND gate group % ANG of the D/A converter DAI, and when adjusting the deflection amount, the gain code G given to the D/A converter DA2 is set.
By changing ce, the conductivity of the transistor Tr is changed, and the gain of the operational amplifier OP2 is changed, thereby changing the charging voltage. In addition, when adjusting the deflection amount, in order to form a charge pattern in the same way as when searching the phase, the dividing period FD2. Antogame) AN3. AN4. An OR gate ORI and an inverter INI are provided.

FIG. 7 shows the deflection amount adjustment control performed by the printing control unit 25. The deflection amount □ adjustment operation will be explained with reference to this flowchart and FIG. 6 □. In addition, the 6th
In the circuit configuration shown in the figure, when the value indicated by the gain code CCC is large, the conductivity of the transistor Tr is high (the point where the gain of CP2 is low and the charging voltage is low, and vice versa when the value indicated by the gain code Gcc is small) Please note that.

When the printing control unit 25 finishes the above-mentioned phase search,
The SW is closed on the side of the printing charge voltage generator 20, and the control signal DG to the circuit 20 is set to a low level "0" which instructs the deflection amount adjustment.
”. As a result, in circuit 20,
AN4 is closed (gate off), AN3 is open (gate on), AND gate AN3 outputs 8 impression charge timing pulses C2 to ORI for 160 μs, and is low for the next 160 μs. 1 which becomes level “0”
C2 distribution butter F-? with a period of 360 μs l'pulse CP
It arises. The uncategorized loop ANC conducts in this C4 distribution pattern and applies the charging voltage code SCC to the D/A converter DAI. The unit 25 subsequently sets the See:Print charge highest level code (charging voltage code for deflecting the ink rffP to the maximum deflection position in print recording) to the output port to the ant gate loop ANC. Then, Gcc=standard gain code (approximately the center value of the adjustment range) is set to the output port to the D/A converter DA2. Then the unit 25
) Set a msec timer (program counter) and wait for it to time out.

With the above settings, 16 consecutive ink particles (160μ
s), 8 of them are charged one after another, and the next 16 consecutive ones (160 μs) are uncharged, forming a charging pattern with one period of 320 μs. Note that during phase search, a charging voltage (corresponding to Pp) is applied to charge 16 consecutive ink particles, but when adjusting the deflection amount, pulse C is applied.
Note that a charging voltage synchronized with P is applied, CP is the frequency of PP, and one ink droplet is generated per pulse PP. In this manner, even when adjusting the amount of deflection, charging is performed using a charging pattern with one period of 320 μs.

The printing control unit 25 detects the output P of the charge detection circuit 23 when the 10m5ec timer times out. Refer to K and set the output gain code to G when it is a low level "0" (ink particles collide with electrode 13). (For example, G.-
8) and high level "1" (the ink particles are at electrode 1).
3), the output gain code is set to G.
. only make it more expensive. That is, when a charged ink particle collides with the electrode 13, the gain is set to G in the direction in which the charged ink particle leaves the upper end of the electrode 13. If the charged ink particles do not collide with the electrode 13, G in the direction in which they collide. Move a lot.

Then, it similarly sets the JQrrLsec timer and waits for lQmsec to elapse. When the time has elapsed, the output P of the charge detection circuit 23 again. P with reference to K
If OK = ro, set the output gain code to 3'2G
o (for example, 4), and if PoK is "1", the output gain code is 36a. 10
Set the m5ec timer ul 0 When the m5ec timer times out, use POK-1OJ to lower the output gain code by 4Go (for example, 2), and POK
= [If it's IJ, /4 Go higher, l Q
Set the m5eC timer. Time Over II...
: When it comes to , it's time for P. If K=,,"IO", lower the output gain code by //4Go L,, 10
Set the m5ec timer. Repeat this for POK-1OJ. As a result of the above, the upper end of the electrode 13 has been removed)
becomes. If this happens, increase the output gain code by the minimum unit (for example 1), set a 10 m5ec timer, and when the time is over, refer to POK and set POK-r.
Similarly to lJ, the output gain code is increased by the minimum unit and the 1Qtrsec timer is set. In this way, at some point in time pox = rOJ. POK
When = ro, . When the above-mentioned control results in POK = ro, the printing control unit 25 sets the control signal DGc to the printing charge voltage generator 20 to "1", closes the AND gate AN3 (gate off), and turns AN4 on. Open (gate on) and notify the printer central control wholesale unit that it is ready (ready for recording). In the state of DGc"=rIJ, if both signals are "1" during the pulse width ([moon level)] of the pulse Cp, the output "1" of A"'N4 is sent to the AND gate group through the OR gate ORI. Since it is applied to ANC, the charging voltage code SCC is applied only when the image signal is "1" in synchronization with CP. Printing control unit 25
When recording starts, a code SCC corresponding to the recording position (deflection position) of each ink droplet is applied to ANG. In addition, while increasing the output gain code by the minimum unit in the above-mentioned deflection amount adjustment, PoK = r (when the output gain code reaches the maximum value without reaching the moon, it is assumed that the ink particles are not charged and the phase search is performed. Return to

In the above example, the standard gain code is first set,
Then G. = '/2Go No. 1c. The charged ink particles are focused on the upper end of the electrode 13 by reducing the amount of change in spoonfuls, and finally, the charged ink particles are first removed from the upper end of the electrode 13, and the output gain code is increased in minimum units to focus the charged ink particles on the electrode 13. When the charged ink particles approach the electrode 13 and the charged ink particles collide with the electrode 13, the gain adjustment is terminated. The gain adjustment may be completed when the charged ink particles no longer collide with the electrode 13. In any case, by changing the path, the charged ink particles converge to a specific trajectory quickly, and when the gain adjustment is completed, the printed charge highest level code and the ink particle deflection trajectory correspond to 1:1. do.

In the phase search and adjustment of the same amount of bias 1 as described above, even if the inner wall of the gutter 12 becomes dirty due to ink splash or mist that collides with the electrode 13 and the insulation between the electrode 13 and the ground decreases, The insulation resistance is IMΩ or more, and is approximately 100KΩ to IMΩ. Therefore, the resistance value of the resistor R is set to 100 Ω or less (and, as mentioned above, the turns of charged and uncharged ink particles) are periodically repeated to generate a pulsation with a period longer than the ink particle generation period. By applying this to the detection circuit, stable and quick deflection detection is performed that is not affected by the DC noise level.During the recording operation, ink does not fly to the gutter 12, so the drop in insulation resistance of the gutter 12 is small, and the phase Even during the search, uncharged ink particles are captured by the gutter 11, so the ink particles heading toward the gutter 12 are only charged particles.Moreover, when this charge is detected, the phase search is terminated, so furthermore, the deflection amount adjustment is necessary. Since the process is carried out quickly, there is little deterioration in the insulation of the electrode 13 during phase search and deflection amount adjustment.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the main parts of a mechanism of an embodiment of the present invention, and FIG. 2 is a block diagram showing main electrical elements. 3 is a circuit diagram showing the configuration of the charge detection circuit 23 shown in FIG. 2, FIG. 4 is a circuit diagram showing the configuration of the phase setting circuit shown in FIG. 2, and FIG. 6 is a circuit diagram showing the configuration of the printing charge voltage generation circuit 20 shown in FIG. 2, and FIG. 7 shows the deflection amount adjustment control of the printing control unit 25 shown in FIG. 2. It is a flowchart. 2.6 = Filter 5: Solenoid valve

Claims (5)

[Claims] (1) Pressurized ink is supplied to the ink jetting port, vibration is applied to the ink jetted from the ink jetting port, and the ink jetted from the ink jetting port is regularly separated into ink particles. A deflection control inkjet recording device that generates charged ink particles by applying a charging electric field and deflects the charged ink particles by a deflection electric field includes: a plate-shaped charge detection electrode with one end adjacent to a predetermined deflection trajectory; and a resistance value within a predetermined range. a resistance means for connecting the plate-like charge detection electrode to a predetermined potential point; a charge means connected to the plate-like charge detection electrode for detecting discharge of charged ink particles colliding with the plate-like charge detection electrode passing through the resistance means; a detection circuit; a deflection search voltage generating means for generating a charging voltage that switches between a charged level and a non-charged level at a predetermined cycle longer than an ink particle generation cycle; and a deflection amount setting means; Detection of a charge detection circuit. A deflection control ink jet recording apparatus configured to change a setting value of a deflection amount setting means by referring to a signal. (2) The deflection control inkjet recording device according to claim 1, wherein the charge detection circuit includes a high input impedance field effect transistor, an amplifier, a filter, an integrating circuit, and a comparator. . (3) The resistance means is a resistor.
The deflection control inkjet recording device according to item 1) or item (2). (4) The deflection control inkjet recording apparatus according to claim 1 or 2, wherein the deflection amount setting means is a printing charge voltage generator. (5) The deflection amount setting means according to claim 1 or 2, wherein the deflection amount setting means is an adjustable gain printing charge voltage generation circuit whose gain can be set from the outside. Control inkjet recording device.