JPS61227059A - Deflection control type ink jet recorder - Google Patents

Abstract

PURPOSE:To uniformize in the early state the viscosity of an ink in an ink- circulating system in supplying a diluent into an ink liquid, by providing an ink tank with an oscillating body for oscillating the ink. CONSTITUTION:An oscillating member 13c is provided in the ink tank 13. The member 13c is a Teflon-made cylindrical body having a center hole, through which a guide bar 13d is passed. The tank 13 is mounted on a carriage on which an ink jet head is mounted, and the carriage is reciprocated in the axial directions of the guide bar 13d. By this reciprocation, the member 13c is reciprocally oscillated along the bar 13d. With the member 13c oscillated, the diluent supplied into the tank 13 is rapidly diffused and mixed into the ink.

Description

Detailed Description of the Invention [Technical Field] The present invention jets vibrated ink from a nozzle, selectively charges the jetted ink at a position where it separates into ink particles using a charging electrode, and transforms the charged ink particles into The present invention relates to an inkjet recording apparatus in which the deflection is caused by a deflection electrode to collide with a predetermined position on recording paper, and particularly relates to ink viscosity adjustment.

■Prior art In this type of inkjet recording, the distance from the ink jet nozzle to the recording paper is relatively long, and therefore the ink pressure is so high that the ink particles ejected from the nozzle and turned into particles are affected by the charging electric field and the deflection electric field. It is set high so that it can reach the recording paper in a stable flight trajectory. In addition, in order to regularly generate ink particles of a predetermined particle size and make them take a predetermined deflection trajectory accurately, it is necessary to maintain stable ink pressure, ink viscosity, vibration pressure, charge amount, deflection electric field, etc. and must be precisely controlled. Also,
If the charging voltage (pulse) is not applied precisely at the timing when the ejected ink separates into ink particles, the ink particles will not be properly charged.

Therefore, conventionally, prior to recording charge control, the ink pressure is stabilized to a constant level, and a phase search is performed to determine the timing of applying the charging voltage pulse relative to the timing of ink particle formation, or vice versa. In this phase search, for example, a charge detection circuit mainly consisting of an amplifier, an integrator, and a comparator is connected to a non-contact or contact type charge detection electrode, and a short charging voltage pulse is applied to the charge electrode. The phase of the charging voltage pulse with respect to ink droplet separation is sequentially shifted at predetermined time intervals. When the charge detection circuit issues a signal indicating "charge", the phase of the charging voltage pulse at that time is determined as the appropriate charging phase.

In deflection control inkjet recording, the ink captured by the gutter is returned to the ink jet head, but the diluent in the ink evaporates before it leaves the head and returns to the ink flow path.
During the continuation of ink jetting, the viscosity of the ink gradually increases. For example, the viscosity changes as shown in FIG. 12a.

Since the amount of deflection is affected by the flying speed of the ink particles, in one embodiment, the flying speed of the ink particles is detected,
The ink pressure is adjusted so that it reaches a predetermined speed. For example, U.S. Patent No. 3,600,9
No. 55 Mingyasho (published August 1971).

Int, C1, Gold 15/13) and Japanese Unexamined Patent Publication No. 50-105733 disclose a technique for detecting ink speed and adjusting ink pressure.

However, the adjustment range for ink droplet velocity and chemotaxis by adjusting ink pressure is extremely narrow, and with high viscosity, even if the ink pressure is increased, the fluctuation in the particle size of the ink droplets becomes large and the recording density may fluctuate. , the amount of deflection fluctuates, or
The ink particle formation becomes disordered, making it impossible to record. This is used when using a constant pressure pump with a constant discharge pressure, a constant flow pump with a constant discharge volume, or a constant pressure or constant flow rate in order to keep the ink pressure constant or the ink droplet size constant. The same applies to any case where the drive of the pump is controlled.

Therefore, it is necessary to adjust the ink viscosity, for example, in JP-A-57-63260 and JP-A-56-1
No. 36381 discloses methods for measuring the specific gravity of ink and supplying a diluent in accordance with the specific gravity, and for example, Japanese Patent Application No. 5
In the invention of No. 9-243976, the ink flying speed is detected, the discharge pressure influencing parameters of the pressurizing pump are controlled so that it becomes constant, the ink pressure is detected, and when the ink pressure reaches a predetermined value, the ink viscosity is The diluent is injected into the ink assuming that the ink has a predetermined high viscosity.

When the diluent is supplied into the ink in this way, the amount of ink in the ink circulation system, which goes from the ink tank to the pressure pump to the ink jet to the radish to the gutter ink tank, becomes considerable. Since the amount of ink to be injected each time is small, it takes a relatively long time to equalize the viscosity of the ink throughout the ink circulation system by continuing ink jetting.

(1) Purpose of the Invention The present invention aims to uniformize the ink viscosity in the ink circulation system at an early stage in supplying a diluent into the ink liquid for adjusting the ink viscosity.

■Structure In order to achieve the above object, the present invention includes a rocking body that rocks the ink in the ink tank to which the diluent is supplied, and urges the rocking body to rock when the diluent is supplied. This speeds up the mixing and diffusion of the diluted liquid into the ink liquid. A carriage carrying an ink jet head is reciprocated during a recording operation. In a preferred embodiment of the present invention, aiming at this, the oscillator is used as the carriage, that is, the ink tank is mounted on the carriage, and the carriage is driven back and forth when supplying the diluent. In order to further speed up the diffusion and mixing of the diluted liquid, in the embodiment of the present invention, the ink chamber wall of the ink tank is made to have unevenness, so that when the ink tank is rocked, the ink flow is disturbed in the ink tank, and the diluted liquid is mixed. speed up the mixing. One more
In one example.

The ink tank includes a vibration member that vibrates within the ink chamber as the ink tank swings.

The embodiments described below further aim to appropriately set the amount of deflection, and more specifically, to appropriately adjust the ink pressure and ink viscosity that affect the amount of deflection. More specifically, the purpose is to appropriately adjust ink viscosity without requiring an additional mechanism.

In this type of inkjet recording, the amount of deflection depends on the ink pressure.
It is determined by ink viscosity, charge amount, deflection voltage, etc., but each has an appropriate range, and it is not possible to set the appropriate deflection amount by adjusting only these considerations over a wide range, and even if the ink pressure is adjusted, the ink If the viscosity is out of the appropriate range, the ink particle size will be out of the specified range and the recording density will vary, the ink particles will become unstable and satellites will stain the recording paper, and the charge will become unstable. recording may become impossible. There is a need for ink viscosity detection and control, but conventional ink viscosity detection is inaccurate and requires a significant number of additional mechanical components.

For example, if the ink pressure is adjusted to a predetermined value by detecting the deflection position or amount of deflection of charged ink particles, or by detecting the flight speed of ink particles, then suppose that the ink pressure falls outside of a predetermined range. Most likely, the ink viscosity is out of the appropriate range, and the ink pressure is correspondingly out of the high or low range. Therefore, by adjusting the ink pressure, control is performed to set the deflection amount or the corresponding ink flight speed to a predetermined value, and if the ink pressure is out of a predetermined range, it is assumed that the ink viscosity is outside the appropriate range, and the ink pressure is adjusted to a predetermined value. If the ink viscosity falls outside the high range of the appropriate range, it can be considered that the ink viscosity has deviated to the high viscosity side, and if the ink pressure has deviated to the low range side, it can be considered that the ink viscosity has deviated to the low viscosity side. Therefore, while performing ink pressure control with a predetermined deflection amount or ink flight speed, if the ink pressure deviates to the high range side, it is assumed that the ink viscosity is high and a diluent liquid may be supplied into the ink. If the ink pressure deviates to the low range side, should the diluent be removed from the ink or should the ink temperature be lowered?

Alternatively, you can replace the ink, but this requires considerable skill and results in a relatively long pause of the inkjet device. This can be avoided by diluent cutout feeding, which supplies a small amount of diluent to the ink.

Therefore, in the embodiment described below, the flight speed or deflection amount (deflection position may also be used) of the ink particles ejected from the ink ejection head and turned into particles is detected, and this is compared with a set value to determine the current flow of the pressure pump. .

At least one of the pressure pump energizing parameters, such as voltage and their frequency, is controlled to obtain a predetermined flight speed or amount of deflection, while ink pressure is detected and when the ink pressure is outside an upper limit. , a relatively small amount of diluent is supplied to the ink.

Note that when supplying diluent, a relatively large amount of diluent should be supplied when the ink has been left for a relatively long time and the viscosity may be extremely high, such as immediately after the power is turned on. It's okay.

For example, when the ink pressure is constant, as shown in Figure 12b, when the viscosity is high, the flight speed of the ink particles is low (the amount of deflection is large), when it is low, it is high (the amount of deflection is small), and the ink viscosity and flight speed ( There is a correlation between
Ink viscosity can be accurately determined by detecting ink flight speed or deflection amount, but when detecting ink flight speed or deflection amount and adjusting ink pressure to the appropriate value, ink pressure must correspond to viscosity. Do - become something.

Therefore, when the viscosity is within a predetermined range, increasing the pump energization parameter will increase the flight speed (lower deflection amount), and lowering the pump energization parameter will result in a lower speed (higher deflection amount), which will stabilize the flight speed at the predetermined value. be converted into If the viscosity is extremely high, the flight speed will be low and even pump control will not be able to provide a stable flight speed (deflection amount), but in the example described below, the diluent is supplied before that, so the ink viscosity will be low. Always maintain a predetermined flight speed (deflection amount) using pump control.
This results in stable flight speed (deflection amount) control. For example, detection of deflection amount and adjustment of ink pressure are disclosed in Japanese Patent Application Laid-Open No. 54-68270, and detection of ink flight speed and adjustment of ink pressure are disclosed in Japanese Patent Application Laid-Open No. 53-61337. These and other known techniques may be utilized in the embodiments described below. As will be described later, it is preferable to detect the ink flight speed and adjust the ink pressure because the ink flight speed can be accurately detected without requiring a particularly large number of or complicated additional elements.

Incidentally, the ink viscosity also varies depending on the ink temperature t, as shown in FIG. 12c. As a result, as shown in FIG. 12e, the relationship between the evaporation rate of water in the ink and the ink pressure shifts in response to the ink temperature. Therefore, it is preferable to keep the ink temperature or the temperature of the environment in which the inkjet recording apparatus is used to be extremely constant, or to ensure that the flight speed is stable even when the ink temperature fluctuates, and that the diluent is not over-replenished.

Therefore, in a preferred embodiment of the present invention, the ink temperature, or a temperature corresponding to the ink temperature such as room temperature or the temperature of the main body of the inkjet recording apparatus is detected, and the ink pressure upper limit value corresponding to the detected temperature (for example, P 1e P in FIG. 12e) is detected. 2) is accessed from the memory, the ink pressure is detected and compared with the upper limit value, and when the ink pressure exceeds the upper limit value, diluent is supplied.

According to this, the contribution of ink viscosity due to ink temperature is compensated, and even if there is a temperature change, over-replenishment or insufficient replenishment of the diluent does not occur.

For example, if constant temperature control is performed with the ink temperature at 30°C, and the evaporation rate of the water in the ink is varied, the relationship between the ink pressure to obtain the appropriate flight speed will be the solid line shown in Figure 13, and the ink temperature will be the same as the ambient temperature. Practically speaking, it becomes the dotted curve at the bottom left. From FIG. 13, it can be seen that when constant temperature control is not performed (dotted line curve descending to the right), the range of ink pressure P that obtains the appropriate flight speed is very wide, and when constant temperature control is performed (solid line), the range of ink pressure P that obtains the appropriate flight speed is very wide. It can be seen that the range of ink pressure P for obtaining speed is narrow. Therefore, when performing constant temperature control, for example, if the evaporation rate of water in the ink is 25% or more, the diluent (
water), the set value for comparison with the ink pressure may be fixed at 4.6 Kg/c+w2. Therefore, in a preferred embodiment of the present invention, an ink temperature sensor, an ink heater, and a constant temperature control circuit are used. Then, constant temperature control is performed to set the ink temperature to a predetermined value, and the set value to be compared with the detected ink pressure is a fixed value.

Further, in a preferred embodiment of the present invention, the pressure pump is energized and controlled by its energization pulse width.

According to this, when the pulse period is 20 m5ec, the energization pulse width with respect to the ink viscosity, when the pressure is constant, is the first
The relationship shown in Figure 2d is shown, and when the viscosity is within a predetermined range, a predetermined ink pressure can be obtained by pulse width control.
The ink pressure is controlled by actually changing the discharge pressure of the pump according to the pulse width signal.

Pulse width control can be performed with high precision using digital processing.

In a preferred embodiment of the present invention, the deviation of the ink droplet flying detection speed from the target value is further determined, the pulse width correction data corresponding to this deviation is read out from the memory, and the This pulse width correction data is added or subtracted from the pulse width signal data currently driving the pump to obtain new pulse width signal data, and the ink pressure pump is driven based on this new pulse width signal data.

According to this, the pulse width correction data is a value that corresponds to the speed of the ink droplet, so the higher the speed, the larger the value, and the smaller the value when the speed is closer to the target value. Therefore, during the repetition of speed detection → pulse width signal change → speed detection → pulse width signal change..., the change in pulse width is large at the beginning, and the change in pulse width becomes smaller as it gets closer to the target. , geometrically, the ink pressure (ink speed) converges to the target value in a relatively short time. The convergence error will be small.

In a preferred embodiment of the present invention, a gutter that is placed between the deflection electrode and the recording paper and captures non-printed ink particles is used as a conductor, and a charge detection circuit is connected to this gutter, and the deflection electric field is cut off when adjusting the pressure. The ink droplets are charged, and counting of clock pulses is started from the application of a charging voltage for this charging, and the count value when the charge detection circuit detects charge is obtained as ink droplet velocity detection data. This data is proportional to the inverse of ink drop velocity. That is, when the ink droplet speed is high, the count value is small, and when the ink droplet speed is low, the count value is large.

The pulse width correction value is associated with the error in the ink droplet velocity with respect to the set target value, and is associated with the absolute value regardless of whether the error is positive or negative. Assign a small correction value to a small absolute value, and add or subtract it from the pulse width signal data when detecting the ink droplet velocity (when the count value is larger than the set target value) depending on whether the error is positive or negative. (When the count value is smaller than the set target value), new pulse width signal data is obtained, and the pump is driven based on this data. This process is repeated until the error is within a predetermined range.

According to this embodiment, since the gutter is also used for ink droplet velocity detection, there is no need to provide a separate ink droplet detection means and there is no need to make the distance from the nozzle to the gutter particularly long. Not only does this increase the length of the head of the printer, which is a big disadvantage in terms of the device configuration, but it also increases the possibility of misalignment of ink flight, which is bad in terms of printing quality.

(2) Embodiment FIG. 1a shows an outline of a mechanical system according to an embodiment of the present invention. The ink in the ink tank 13 with the cartridge 15 installed is
It is sucked by the pump 1 and fed under pressure to the accumulator 2.

The pressurized ink sent to the accumulator 2 has pressure vibrations suppressed by the accumulator 2 and the filter 3, and reaches the ink jet head 5 through the electromagnetic switching valve 4.

In the ink ejecting head 5, the electrostrictive vibrator is excited and energized at a constant period and a constant amplitude, and applies pressure vibrations at a constant period and a constant amplitude to the ink within the head 5. Ink is ejected from the nozzle of the head 5, and due to this pressure vibration, the ejected ink separates into particles at a position that has advanced a predetermined distance from the nozzle.

This particle formation corresponds to the pressure vibrations applied to the pressurized ink in the head 5, and the ejected ink corresponds to one part of the pressure vibrations.
Particles are formed at a rate of one ink droplet per cycle. By applying a charging voltage between the charging electrode 6 and the ink in the head 5 at the timing when the ejected ink becomes particles,
The atomized ink particles have an electric charge, and charged ink particles and uncharged ink particles are formed depending on whether or not a charging voltage is applied to the electrode 6 in accordance with the atomization of the ink.

The charged ink particles are deflected by the electric field of the deflection electrode 7 and collide with the recording paper 8, while the uncharged ink particles travel straight and collide with the conductive gutter 9, pass through the filter 11, are sucked by the pump 12, and are sent to the ink tank 13. is discharged.

A pressure sensor 40 is attached to the accumulator 2,
This detects the ink pressure within the accumulator 2. The ink jet head 5 is equipped with a temperature sensor.

The ink jet head 5 is as shown in FIG. 1b.

It has a structure in which a ceramic head 5b is attached to the tip of a pipe to which an electrostrictive vibrator 5a is attached. ceramic head 5b
A nozzle member 5c and a temperature sensor 18 are fixed to the tip of the nozzle member 5c. The electrostrictive vibrator 5a and the ceramic head 5b are housed in a stainless steel tube 5d.
A somewhat flexible insulating material 5e is filled between the two.

Referring again to FIG. 1a, an electrode 17 for detecting the remaining amount of ink is attached to the bottom of the ink tank 13, and this electrode 17 is grounded to the equipment.

A stainless steel pipe 15c extends from the top of the ink tank 13 to near the bottom, and another electrode 16 for detecting the remaining amount of ink is connected to this pipe 15c. When there is more than a predetermined amount of ink in the ink tank 13, the pipe 1
5c is electrically connected to the electrode 17 via ink, and the electrode 16 is substantially at the equipment ground level. but,
When the ink level falls below the lower end of the pulp 15e,
Electrode 16 is electrically isolated from equipment ground level.

Therefore, it can be determined from the potential of the electrode 16 whether the amount of ink in the ink tank 13 is less than a predetermined amount.

In this embodiment, the elements surrounded by two-dot chain lines in FIG. 1a are mounted on a carriage (not shown), and the carriage is driven back and forth in a direction perpendicular to the paper plane of FIG. 1a. The configuration in which the ink tank is mounted on the carriage is based on Japanese Patent Application Laid-Open No. 58-865.
It is disclosed in Publication No. 5.

In this embodiment, the first
The elements surrounded by two-dot chain lines in Figure a are mounted on the carriage.

The bottom of the ink tank 13 is a bottom plate having two peaks 13a and 13b. In order to facilitate understanding, the peaks 13a and 13b are shown as extending parallel to the reciprocating direction of the carriage (direction perpendicular to the paper surface) in FIG. is along a direction rotated at right angles to the illustrated state, that is, a direction perpendicular to the reciprocating direction of the carriage. When the carriage reciprocates, the ink in the ink tank forms a mountain 13a.

It ran aground on 13b and fell into a valley between mountains, causing ink to be disturbed. As a result, when the diluting liquid is supplied into the ink tank, the diluting liquid mixes well with the ink in the ink tank. Similarly, unevenness may be formed on the side wall of the ink tank 13.

In another embodiment of the present invention, a vibrating member 13c is provided within the ink tank 13, as shown in FIG. 1c. In this example, the vibration member 13c is a cylindrical body made of Teflon and has a center hole, and a guide bar 13d passes through the center hole. In this example, the ink tank 13 is mounted on a carriage carrying an ink jet head, and the carriage reciprocates in the direction in which the guide bar 13d extends. This reciprocating motion causes the vibrating member 13c to reciprocate along the guide bar 13d. When the diluent is supplied to the ink tank 13 due to the vibration of the vibrating member 13c, the diluted liquid is quickly diffused and mixed into the ink.

A level detection circuit 39 shown in FIG. 3b is connected to the electrode 16 shown in FIG. 1a. A 390Hz electric pulse is applied to the level detection circuit 39 from a pulse generator 19 (FIGS. 2 and 3a), which will be described later, and this is applied to the coupling capacitor 39b, resistor 39c, and diode 39.
d to the integrating capacitor 39e. The electrode 16 is connected between the resistor 39c and the diode 39d.

The voltage of capacitor 39e is determined by resistor 39f and comparator 39.
applied to g. A reference voltage of a predetermined potential is applied to the comparator. The binary output of the comparator is applied to the base of a transistor 39m via a resistor 39h, clamp diodes 39i, 39j, and a resistor 39k. transistor 39
The emitter of m is connected to a constant voltage terminal, and the collector is connected to a light emitting diode 39n. In the ink tank 13, when the ink level is above the lower end of the pipe 15c, the electrode 16 is at the equipment ground level, the 7 node of the diode 39d of the circuit 39 is substantially at the equipment ground level, and the comparator 39g is at the high level H. is output.

A high level H indicating the presence of ink is applied to the printing control device 29 (FIG. 2), which will be described later, and the transistor 39m is turned off and the light emitting diode 39n does not emit light.

When the ink level drops below the lower end of the pipe 15c and the electrode 16 is electrically separated from the ground level, 39
A 0Hz pulse is applied to the integrating capacitor 39e, the voltage of the capacitor 39e increases with a time constant determined by the values of the capacitor 39e and the resistor 39f, and the output of the comparator 39g becomes H.
is inverted from to low level L. This is a printing control bag! !
A signal indicating a low ink level is applied to the transistor 29, and the transistor 39m becomes conductive, causing the light emitting diode 39n to become conductive.
emits light. In this light emitting state, the ink level is pipe 1.
Continue until it reaches the lower end of 5c.

Referring again to FIG. 1a. An ink injection adapter 15e is fixed to the upper end of the stainless steel pipe 15c extending below the ink tank 13. In addition, the lower end of another stainless steel pipe 15d has entered the ink tank 13,
The upper end of this pipe 15d is connected to the output port of the electromagnetic on-off valve 14. A diluent injection adapter 15f is connected to the input port of the electromagnetic on-off valve 14.

The ink injection port and diluent injection port of the cartridge 15 are removably engaged with the adapters 15e and 15f, respectively.

The cartridge 15 has a divided ink chamber 15a and a diluent chamber 15b. An air vent is provided at the bottom of the diluent chamber 15b (located on the upper side in FIG. 1a), and this air vent is connected to the stopper 15 in the state shown in FIG. 1a.
It is closed with g.

After the cartridge 15 is installed in the ink tank 13 as shown, the stopper 15g is removed from the cartridge 15. When the solenoid on-off valve 14 is opened, the air ventilation port is 1.
It is opened so that the diluent flows smoothly and quickly into the ink tank 13.

As explained above, the reason why the 15 cartridges contain both the ink liquid and the diluent liquid and are replaced at the same time when a new cartridge is replaced is as follows. That is, in the viscosity control method of diluent injection, when the printing duty (the amount of ink used for recording relative to the amount of injected ink) is low, the antifungal agent contained in the diluted liquid increases in the circulating ink by injecting the diluted liquid. An increase in the amount of antifungal agent in the circulating ink causes fluctuations in the injection direction due to solid content precipitating at the injection port, clogging when left for a long period of time, and reliability becomes a problem. Therefore, the amount of anti-mold agent in the diluent needs to be smaller than the amount of anti-mold agent in the ink. For example, if the new ink to be stored in the cartridge 15 contains 0.3% antifungal agent, the antifungal agent in the diluted solution should be 0.1% or less, and when replacing the ink, the diluted solution (also (The concentration of the antifungal agent increases as it evaporates from the ink.) Even if some remains, replace it at the same time to prevent the amount of antifungal agent from increasing in the circulating ink.

On the other hand, methods for detecting the remaining amount of a non-conductive diluent are limited, and an electrode type cannot be used. If the cartridge 15 is configured so that some diluent remains even when the new ink runs out, the diluent will be automatically replenished when replacing with new ink, and the diluent will be refilled just by detecting the remaining amount of ink. Remaining amount detection becomes unnecessary. For example, set the amount of circulating ink to 30cc.
(If this amount is large, it will take a long time to wait for mixing and diffusion when the diluent is supplied into the ink), the amount of new ink stored in the cartridge 15 is 30 cc, and the amount of diluted liquid in the storage is 20 cc.

Referring again to FIG. 1a, in the ink reservoir 13.

The diluent in the cartridge 15 is supplied via the electromagnetic on-off valve 14 . Valve 14 is normally de-energized and closed.

When the electromagnetic switching valve 4 is energized, the filter 3 and the head 5 are communicated, and the pipe 40 is cut off from them, and when it is not energized, the head 4 and the pipe 40 are communicated, and the filter 3 is cut off from them. .

FIG. 2 shows the configuration of an electrical system that energizes each mechanical element shown in FIG. 1 and also performs charge recording control and ink viscosity control.

A sine wave generation/amplification circuit 25 applies an excitation voltage to the electrostrictive vibrator of the ink jet head 5 . A charging signal amplifier circuit 26 applies a pulsed charging voltage to the charging electrode 6, and a deflection voltage generating circuit 27 applies a high voltage at a constant level to the deflection electrode 7.

One end of a core wire of a shielded wire 10 is connected to the conductive gutter 9, and a charge detection circuit 30 is connected to the other end of the core wire.

Pumps 1 and 12 are electrically energized by pump drivers 21 and 12, respectively, and pump drivers 21 and 32, respectively. The electromagnetic switching valve 4 and the electromagnetic on-off valve 14 are electrically energized by valve drivers 24 and 34, respectively.

In this embodiment, in order to charge the ink at a predetermined timing in detecting the flying speed of the ink particles, and to apply a search pulse voltage to the electrode 6 in a phase search in which the center of the charging voltage pulse is aligned with the separation phase of the ink particles, and
A timing pulse generator 20 for ink pressure retrieval is used to apply recording charge voltages of different levels stepwise to the electrodes 6 during printing. A search charge signal generator 23 and a record charge signal generator 22 are provided, and signals from these generators are selectively applied to a charge signal amplification circuit 26 by a gate circuit 28 . The operation timing of each part of the electric circuit element is determined based on a plurality of types of timing pulses generated by the pulse generator 19.

A printing control device (ink viscosity control means) 29 mainly composed of a microcomputer 31 energizes and controls each part.

In Figure 3a, pulse generator 19. Gate circuit 28, recording charge signal generator 22. Search charge signal generator 23. The configurations of the tanning pulse generator 20 and the printing control device 29 and the connections therebetween are shown.

The pulse generator 19 is composed of a pulse generator 19a including a crystal oscillator and a branch counter, and a divide-by-1 counter 19b, and has a frequency of 3.2 MHz, 800 KHz, 400 KHz,
200K) 1z, 100KHz, 100/32 = 3.
125KHz, 133KHz, 33KHz and 39
Generate nine types of 50% duty pulses at 0 Hz.

The 100 KHz pulse is generated by a sine wave generation/amplification circuit 25.
is applied to The circuit 25 generates a sine wave of the fundamental frequency component of the input pulse, amplifies it, and applies it to the electrostrictive vibrator of the head.

As a result, pressure vibrations of LOOKHz are applied to the ink in the head 5, and ink particles are formed at a rate of 100XIO' particles/sec and fly toward the gutter 9 or the recording paper 7. That is, ink particles are generated at a frequency of 100 KHz.

The recording charge signal generator 22 has a counter for frequency division by 172 (
It consists of a T flip-flop (T flip-flop) 22a, a serial-in/parallel-out 8-bit shift register 22b, a data selector 22c, and a charge code generator 22d consisting of a counter, a decoder, and an output gate.

A 100 KHz pulse is input to the counter 22a, and the counter 22a applies a 50 KHz pulse to the shift register 22b as input data. The shift clock of shift register 22b is an 800 KHz pulse. FIG. 5 shows eight sets of pulse outputs (CHP) of the shift register 22b. These eight sets of pulses are applied to the data selector 22c.

A 3-bit output control code is further given to the data selector 22c, and this code instructs the output of one set of eight pulses.

Since the shift register 22b is shift-energized with 800 KHz pulses, the eight sets of pulses a=h are in this order 0. The data selector 22c has the same cycle and the same duty with a phase delay of OO125 msec.
The data specified by the 3-bit code given to is selected by the data selector from the AND gates AO to A9 of the gate circuit
is output to.

The search charge signal generator 23 is composed of a decoder 23a and a data selector 23b.
Three sets of pulses are applied at 100, 200 and 400 KHz. As a result, the output of the decoder 23a is
There are eight sets a to h shown as SP in FIG. 5, and their pulse widths are 0.00125.times.56C, and the phases are shifted by the pulse width, that is, 0.001251 seconds.

The same 3-bit control code as the 3-bit control code given to the data selector 22c of the recording charge signal generator 22 is also given to the data selector 23b, and the search charge signal a is generated as follows.
= Output h.

Control code 0000010100111001011
Output of 1011122c abcdefgh Output of 23b defghabc The output pulse of the data selector 23b is applied to the AND gate AIO of the gate circuit 28.

The timing pulse generator 20 includes two J-type flip-flops 20a, 20b, an AND gate 20c, and an inverter 20d.

100/32 KHz to Tamming Pulse Generator 20
pulse is given as a clock pulse, and the microcomputer 31 has a width of 0.36+wsec (50K
A pulse rHJ having a width slightly longer than 32 cycles of Hz is applied once every time an ink droplet flying speed is detected.

FIG. 6 shows input and output signals of the tanning pulse generator 20. AND gate 2 of the tamming pulse generator 20
The output of 0c (R27) is given to the gate circuit 28.

FIG. 4 shows a charge detection circuit 30 and a pump driver 21.
The configuration is shown below.

The charge detection circuit 30 includes a resistor 30a that grounds the shield wire 0 to the device, and a field effect transistor (FET) 3.
0 b, anti-phase amplifier 30c, bypass filter 30d
, half-wave rectifier 30e, integrating circuit 30f and comparator 30
It is composed of g.

The resistance value of resistor 30a is between gutter 9 and earth filter 1.
The resistance value is set to about 100KΩ, which is smaller than the resistance value between the two when they are connected with ink.

There is a slight stray capacitance between the core wire of the shield wire 10 and the equipment ground, and in this embodiment, the ink particles are negatively charged, and each time a charged ink particle collides with the gutter 9, the core wire of the shield wire 10 is However, due to the time constant of the stray capacitance and the resistor 30a, when the charged ink particles continuously collide with the gutter 9, the potential of the core wire continues to be a negative potential. It has become.

Therefore, when charge control is performed such that a plurality of consecutive elements are charged and the next plurality of consecutive elements are uncharged, a potential pattern corresponding to this charged/uncharged pattern appears at the gate of the FET 30b. This potential pattern is converted into a current by the FET 30b, inverted and amplified by the amplifier 30c, low frequency noise is removed by the bypass filter 30d, and then applied to the half-wave rectifier circuit 30e. The charge detection circuit 30 detects that when no charged ink particles collide with the gutter 9, P19=
1 (high level), and when charged ink particles are colliding with the gutter 9, an output of P19=O (low level) is produced.

The pump driver 21 is a microcomputer (hereinafter referred to as C
21a, a D flip-prop 21b, a buffer amplifier 21c, Output circuit consisting of transistors 21e, 21f, 21g, etc., counter 2 for pump drive pulse width adjustment
1d, an AND gate 21h, a delay circuit 211, and the like.

A 50 Hz pulse and a pump drive-on signal P15 are input from the pulse generation circuit 19 to the AND gate 21a of the pump driver 21. The counter 21d is a counter that can be preset with data, and is a counter that can be preset with data.
Load the pulse width signal data Pd from 9.
Preset with input signal. The load input applies a 50Hz pulse to one input terminal of the Nant gate 21h, and
By inverting the rising edge of the 50Hz pulse with an inverter, delaying it, and inputting it to the Nant gate 21h, the Nant gate 21h is activated at the rising edge of the 50Hz pulse.
It is generated by In other words, the counter 21d has a frequency of 50Hz.
Load Pd at the rising point of the pulse. Then, the counter 21d subtracts 1 from the value indicated by Pd every time a 33 KHz pulse arrives, and when the number of arriving pulses matches the Pd value (when the remainder of the subtraction becomes 0), the carry is sent to the flip-flop. 21b to the clear input terminal CR.

Since the flip-flop 21b is set at the rising edge of the 50 Hz pulse to make the Q output a high level H, the Q output of the flip flop 152 has a frequency of 50 Hz and a pulse width of the high level H of 33 KHz. P
This results in d pulses and is applied to the output circuit. The output circuits (218 to 21g) switch using this Q output and apply a pulse voltage to the pump 1 that is synchronized with the Q output pulse. The width of this pulse voltage corresponds to the H width of the Q output and is determined by Pd.

7a and 7b show the characteristics of the pump 1 energized by the output pulse voltage of the pump driver 15. FIG. pump 1
By applying the above pulse voltage to the electric coil of
In the pump 1, the armature is pulled by the coil core, the diaphragm is displaced, the volume of the liquid chamber increases, a negative pressure is created, the suction valve opens, and ink is sucked. While the pulse voltage is negative, the diaphragm returns due to the spring force of the diaphragm, and the volume of the liquid chamber becomes smaller, resulting in a discharge stroke. When supplying the same pressure to the head 4, for example 4 Kg/cm,
When the +pulse width is 13m5ec and 50% or more of the pulse period of 20m5ec, the suction stroke takes in 13+asec, and the liquid chamber negative pressure becomes a small value of about 0.4 K g/cra. When the width is 7 m5ec, which is less than 50% of the pulse period, the suction stroke time is short, so the generated negative pressure has a large value of about 0.8 K g/cm''. The current peak value at this time is larger than that at 13 m5ec. This large negative pressure generated within the liquid chamber generates bubbles due to the cavitation phenomenon, which causes instability of the discharge pressure.

In particular, since the amount of dissolved oxygen in the ink is large due to the circulation of the recovered ink, it is necessary to keep the value of the generated negative pressure small. Pressure control is performed so that the pressure of the ink supplied to the head 5 is controlled within a range of approximately 4 to 5.5 Kg/c+*" in order to keep the flight speed of one drop constant due to environmental temperature and viscosity increase due to moisture evaporation. In order to keep the generated negative pressure low by varying this with the peak value of the pump current using pulse width control, it is necessary to
The above conditions are satisfied by setting the suction stroke to a time width of about 10 m5 ec to 15 Sec when the pulse is 0 Hz.

Therefore, the value of Pd is set in the range of 11.5 to 13.5 m5ec, and the upper limit of Pd (Pwtu
) to 10 of 11.5 to 13.5 m5ec from the high side
It is divided into stages. The lower limit of Pd can also be changed depending on the ink temperature t, but in this example, the lower limit (P wts) is 1
It is fixed at 1.5m5ec.

A temperature sensor (thermistor) 18 is attached to the ink jet head 5 to detect the temperature of the head 5b, and a temperature detection circuit 38 is connected to the thermistor 18. The configuration of the temperature detection circuit 38 is shown in FIG. The thermistor 18 has low resistance at high temperatures and high negative resistance at low temperatures.

The voltage of the thermistor 18 is applied to the opposite polarity input terminal (-) of the operational amplifier 38a. If the temperature is high, the operational amplifier 38a
output becomes high and decreases when the temperature is low. The output of the operational amplifier 38a is converted into digital data by the A/D converter 38b and is constantly applied to the data selector 42.

The pressure sensor 40 attached to the accumulator 40 generates an analog signal corresponding to the ink pressure, and this analog signal (pressure signal) is sent to the pressure detection circuit 41.
(Figure 2). Like the temperature detection circuit 38, the pressure detection circuit 41 also has an A/D converter, converts a pressure signal into digital data, and constantly applies the digital data to the data selector 42.

One of the temperature data and pressure data given to the data selector 42 is given to the microprocessor 31 of the printing control device 29. When referring to temperature data, the microprocessor 31 of the printing control device 29 instructs the data selector 42 to output temperature data and reads the output data, and when referring to pressure data, outputs the pressure data to the data selector 42. 42 to read the output data.

The printing control device 29, which is an ink pressure and viscosity control means, is connected to a central processing unit (microprocessor) 31. R.O.
M33. RAM34. This is a general-purpose computer composed of an I10 board 35, a system controller 36, etc., and controls each element described above.

FIG. 9 shows an overall outline of the control performed by the microprocessor 31, FIGS. 10a and 10b show details of the adjustment control of ink pressure, etc., and FIG. 11 shows the interrupt processing for adjusting the ink pressure, etc. show.

First, the overall outline of the control will be explained with reference to FIG. When the power is turned on, one microprocessor 31 initializes the output ports and sets each control element to a safe state (
Step 1: The word step will be omitted hereafter). At this time, the deflection voltage generation circuit 27 is turned off, the pump driver 21.32 is also turned off, and the valve driver 24.3 is turned off.
4 is also set to off, and AND gate All is also set to off. In other words, the ink ejection is stopped.

When the initialization is completed, the microproset 31 first outputs and sets a drive instruction signal to the pump driver 21 to put the pump 1 into a driving state (2a), and waits for the elapse of time T1 (2a).
2b). Next, an energization instruction signal is output to the valve driver 24 to energize the electromagnetic switching valve to the filter 3-head 5 flow state (3), and a drive instruction signal is output to the pump driver 32 to drive the pump 12. state. Then, the preparation timer (program timer for T2 period) is turned on (5).

As a result, ink is ejected from the ink ejection head 5, collides with the gutter 9, is sucked by the pump 12, and is ejected into the ink tank 13, thereby starting an ink cycle.

In this embodiment, the pump 1 is of a constant pressure type in which the discharge pressure is constant. Other types of pumps may be used to provide constant pressure control.

There, the microprocessor 31 waits for the preparation timer to time out (8), reads the status of each part while waiting, and outputs status data to the host device or operation board according to the status (6). It is in a state where it is possible to record photos (7
), when the preparation timer times out, the phase search (9)
Proceed to After completing the 0 phase search, ink pressure, etc.! ! l4w1(
Proceed to step 10), and after adjusting the ink pressure, etc., phase search is executed again (step 11), and then proceed to recording control (step 12). When recording is finished, the process proceeds to a stop process similar to initialization. Note that while the preparation timer is counting time, the ink pressure from the accumulator 2 onwards increases to a pressure corresponding to the operating speed of the pump 1, and when the preparation timer times out, it remains stable at a certain pressure.

In the phase search (9, 11), the microprocessor 31:
The 3-bit code given to the data selectors 22c and 23b is set to 000, and the AND gate All is opened (gate-on) to start time measurement.

As a result, the data selector 22c selects the CH shown in FIG.
The data selector 23b outputs a of P and d of SP shown in FIG. 5, but since the printing data is L (not recorded), the output gate of the charge code generator 22d is closed, and the charge code The outputs (charge level indication codes) of the generator 22d are all L (0000000000), and the AND gates AO to A9 are all closed. But AND gate A10 has 100/32=3.12
5KHz pulse is applied, so 100KHz
open for 16 cycles (during the generation of 32 ink droplets) and then for the next 16 cycles (during the generation of 32 ink droplets).
is closed.

Repeat this below, and the AND gate AIO
, All and through the orgate R4.

The SP pulse d shown in FIG. 5 is applied to the OR gate RO-R3.
Of these, 32 consecutive pieces are given, then 32 consecutive pieces are given again after a rest period of 32 pieces, and so on.
SP d (FIG. 5) is applied intermittently. While d of SP is given 32 times in a row, the D/A converter 28a
00100111 only during the period when d of sp is H.
00 is applied, and the D/A converter 28a provides the charge signal amplification circuit 26 with a charge signal at a level corresponding to 0010011100.

As a result, charging voltage pulses are applied to the charging electrode 6 in synchronization with d of SP, and in a pattern in which 32 consecutive pulses appear, then a pause for 32 consecutive pulses is placed, and then 32 consecutive pulses appear. is applied.

If these charging voltage pulses match the timing of ink particle formation, the ink particles will be charged, but if they do not, they will not be charged.If they are charged, 32 consecutive charged ink particles will be followed by 32 consecutive charged ink particles. The ink droplets fly in a charging pattern of 32 uncharged ink droplets followed by 32 consecutive charged ink droplets.

At this time, the bypass filter 3 of the charge detection circuit 30
At the output end of 0d, the potential is positive while 32 consecutive charged ink particles collide with the gutter 9, and the potential is negative while 32 consecutive non-charged ink particles collide with the gutter 9. 1
A signal with a period of 00/32=3.125 KHz appears.

This signal is rectified by a half-wave rectifier 30'e and integrated by an integrating circuit 30f.

When the integrated voltage exceeds the set value, the output of comparator 30g becomes H.
Inverts from to L.

The microprocessor 31 outputs the output P19 of the comparator 30g.
changes from H to L, then the data selectors 22c, 2
The 3-bit code outputted to 3b is assumed to bring about the proper charging timing that gives the proper charge, and is outputted as it is to the data selectors 22c and 23b, and the AND gate All is turned off to perform the first step 10 or 1.
Proceed to step 2.

As mentioned above, set the 3-bit code 000 to the data selectors 22c and 23b, and open the AND gates (
If the output P19 of the comparator 30g does not invert from H to L after the timer is set and the timer times out, the microprocessor 31 will set the data selectors 22c and 23b to 001. Set the 3-bit control code to output, and similarly set the timer. Then, it waits for the output P19 of the comparator 30g to change from H to L. When the 3-bit control code 001 is set in the data selector 22C223b, the data selector 2
2c then outputs the signal CHP b shown in FIG. 5, and the data selector 23b outputs the signal CHP b shown in FIG.

Output e of signal SP. That is, the data selector 22
Both c and 23b are 1/8 of the last output signal.
Outputs a pulse whose phase is delayed by 00m5ec.

Except for the fact that the signal phase is delayed like this.

The operations of each part are the same as those described above when outputting 000 to the data selector 22C223b.

Then, when the output P19 of the comparator 30g changes from H to L, the microprocessor 31 selects the data selector 2.
The 3-bit code output to 2c and 23b is assumed to bring about the proper charging timing to give the proper charge, and is output to the data selectors 22c and 23b as is, and the AND gate All is turned off to adjust the ink viscosity. (10) or proceed to recording control (11). Comparator 30g
When the timer times out while the output P19 remains at H, the microprocessor 31 outputs 010 to the data selectors 22c and 23b.

Similarly, the microprocessor 31 operates the comparator 30g.
As long as the output P19 of the data selector 22c is H, each time the timer times out.

The 3-bit control code given to 23b is updated.

As shown in FIG. 5, the pulse width of signals a to h of the signals sp output by the data selector 23b is 1/800 m5ec.
Since the phase is shifted by the pulse width from each other, while changing the 3-bit control code in the range of 000 to 111,
Each of a = h in P is selectively AND gate AI
When one of the 3-bit control codes is output to the data selectors 22c and 23b, the ink particles become charged, and the output P19 of the comparator 30g changes from H to L. The microprocessor 31 then ends the phase search.

The 3-bit control code output to the data selectors 22c and 23b is set to be output as is, and the AND gate All
is closed (off) and the next control step (10 or 12
).

Next, ink pressure adjustment (lO) will be explained with reference to FIG. 10a, tob, and 11.

When proceeding to adjust the ink pressure etc., the microprocessor 31
Clear the charge detection flag 17), charge detection circuit 30
Refer to the output P19 (18).

Here, if P19=1 (no charge detected), the charge detection circuit 30 is in a standby state, so proceed to the next step 19, but if P19=O (charge detected), the output P19 of the charge detection circuit 30 Wait until becomes 1. And P19=
When it becomes 1, the process proceeds to the next step 19.

In step 19, the microprocessor 31 enables interrupts for the port receiving the zero-crossing pulse. As a result, when a zero-cross pulse (0 level) arrives, the microprocessor 31 proceeds to II-inclusive processing (FIG. 11).

Now, when the interrupt enable is set, the microprocessor 31 updates the signal SR applied to the clear input terminal of the counter 37 (FIG. 2) from the clear instruction level 0 to the count enable level 1 (20), and the timing pulse generator 20 J
- output the set signal P26=1 to the flip-flop 20a (21), output set the ON signal CE=1 to the AND gate 39 (FIG. 2) (22), and start time counting (23). As a result, the counter 37
starts counting up the pulse C27 of 133 KHz, and a charging voltage is applied to the charging electrode 6. When the time count value reaches 0.36 m5ec, the microprocessor 31 outputs P
26 is returned to 0 (26). As a result, the microprocessor 31 outputs the high level H signal P26 (see FIG. 6) for 0.36a+sec.

Flip-flop 20a of the tamming pulse generator 20
is 100/32=3.125KH applied to the clock pulse input terminal GK after P26 becomes high level H.
Set when the pulse of z is at low level L. As you can see from Figure 6, 100/32=3.1
By the time the 25KFlz pulse changes from L to H and then back to L, the signal P26 is returned to L, so 3.125
When the KHz pulse becomes low again, flip-flop 20a is reset and flip-flop 2
0b is set.

As a result, the output R27 of the AND gate 20C becomes H after the signal P26 becomes H as shown in FIG. 6. 3.1
It is synchronized with the 25 KHz pulse and becomes high level H only during that cycle. During this high level H period, 32 ink droplets are generated. Output R2 of AND gate 20c
7(H) is applied to the OR gates RO to R3 through the OR gate R4 in the gate circuit 28. This results in
Code 001 instructs the D/A converter 28a to a predetermined charge level while exactly 32 ink droplets are generated.
0011100 is applied. Therefore, while 32 ink particles are generated, the D/A converter 28a
continuously applies a voltage at a predetermined level to the charge signal amplification circuit 26. This charges 32 consecutive ink particles.

Set P26=O (26)L, then the microprocessor 31 starts counting time again (27), then 1
, wait for the elapse of 60m5ec (28).

While waiting for 0.36 sec to elapse after setting P26 to 1 (24) and while waiting for 1.60 m5 ec to elapse after resetting P26 to O (28),
The microprocessor 31 refers to the presence or absence of the charge detection flag (25.29).

The flight time T of the ink particles traveling straight along the distance from the charge detection electrode 6 to the gutter 9 is approximately 1 m5 ec.

Thirty-two consecutive charged ink particles fly and collide with the conductive gutter 9, and after the first one of the charged ink particles collides, the potential of the core wire of the shield wire 10 decreases in the negative direction. Initially, after all 32 charged ink particles collide, the potential rises and shows an approximately pulse-like change. Corresponding to this potential change, the output of the amplifier 30c changes in the positive direction in an approximately pulse-like manner, and the output of the amplifier 30c when it stands up in the positive direction.

That is, immediately after a series of 32 charged ink droplets collide with the conductive gutter 9, the zero-crossing pulse generator generates a zero-crossing pulse (0 level), and in response, the microprocessor 31 generates a zero-crossing pulse (0 level) as shown in FIG. Proceed to interrupt processing.

In the interrupt processing, first, the gate control signal CE to the AND gate 39 is reset to the off instruction level O (52
). This causes the counter 37 to stop counting up. Next, the charge detection flag is set 53), the count value of the counter 27, that is, the detection time (flight time) T is read into the register T (54), and the counter 37 is cleared (SR is reset to 0). Return to ink pressure adjustment as shown in the figure.

Since the charge detection flag is set when the ink pressure etc. adjustment returns, this is detected in step 25 or 29, and the process proceeds to step 30, where temperature data t is read and set in register t (30).

Next, from among the threshold groups stored in advance at a predetermined address (threshold table) in the ROM 34, an address is specified based on the value of the register t, and one ink pressure upper limit threshold P■
Read out the fixed lower limit pulse width threshold Pvtg (31), and calculate the flight time deviation Cc (32).
), C in Cc=C−Cs is the content T of register T,
Cs is target flight speed data (unit of T) that is input to the printing control device 29 from a keyboard or an input device (not shown) and set in the memory.

Referring now to FIG. 10b, microprocessor 31
Compare the absolute value of the data Cc with the maximum allowable value Cm (fixed value)33). If Cc is greater than Cm, the ink particles are not charged or the ink is not being ejected.1 etc. Since the ink jetting etc. are abnormal, the ink jetting is stopped and an alarm is set (34). Thereafter, the device power remains in that state until it is turned off and turned on again.

If Cc is less than Cm, it is considered normal, and the deviation Cc is 2.
Check whether it is within the range (35). 2, the deviation Cc of the actual flight speed C from the target flight speed (flight time) Cs is within the allowable range, and in that case, the pump driver 21
The pulse width signal data Pd (standard value Pd5 for the first time) applied to provides an appropriate ink speed. However, in order to check whether the ink viscosity is appropriate, the ink pressure P
is read and compared with the ink pressure upper limit threshold Pa. If the detected ink pressure P is less than Pm, the ink viscosity can be considered to be within the appropriate range, so the viscosity m! Finish I and proceed to recording (12). If the detected ink pressure P is greater than or equal to the ink pressure upper limit threshold Pm, the ink viscosity is too high (in this embodiment, the water evaporation rate is 25% or more), and the ink pressure upper limit threshold Pm is P1 in FIG. 12e.
~P2, the value corresponding to the ink temperature t at that time)
Therefore, the process proceeds to step 41 and subsequent steps to control the diluent supply (described later).

If the deviation Cc exceeds 2 in step 35.

It is not considered that the ink speed has reached the target value Cs,
36), and according to the absolute value and sign, convert the absolute value into memory address data, access the memory 28, read out the pulse width signal correction value ΔVpd corresponding to the absolute value, and read out the pulse width signal correction value ΔVpd corresponding to the absolute value. Depending on the sign of
The pulse width signal data Vpd to be updated to 1 and given is determined (37.47).

Note that a correction code table (memory area) is set in the ROM 33, and this table stores pulse width signal correction value data ΔVpd associated with the absolute value of the deviation Cc, and is accessed based on the deviation Cc. It is supposed to be done. The correction value ΔVPd is made linear with respect to the deviation Cc. Therefore, when the deviation Cc is large, the correction value data ΔV is read out from the memory 28 based on it.
pd becomes a large value, and when the deviation Cc is small, the correction value data ΔVpd read from the correction value code table based on it becomes a small value.

Next, when calculating with Vpd=Vpd+ΔVpd,
Read the detected ink pressure P and compare it with the ink pressure upper limit threshold Pa (38). If the detected ink pressure P is greater than or equal to the upper limit threshold 21, it is assumed that the ink viscosity is out of the appropriate range, and step Proceed to diluent supply below 41,
In supplying the diluent, first, the valve open signal 3 is sent to the valve driver 34.
Set the output to 4S=1 to open the electromagnetic on-off valve 14.
1) Set the timer DT (program timer) (
42) Wait for the time to elapse (43), and when the time elapses, return the electromagnetic on-off valve 14 to close (34S=0) 44
), the carriage is set to reciprocate m times and the carriage drive is started (45), and when the m reciprocations are completed, the carriage is returned to the home position (46) and the process proceeds to phase search (9).

Note that DT is the time for supplying a predetermined amount of diluent, and m times is the time required for the supplied diluent to be sufficiently stirred in the ink tank 13 and for the stirred ink to be ejected from the head 5. This is the number of times the carriage is reciprocated during the period. m
When the carriage reciprocating drive is completed, since the ink viscosity has changed, the phase search (9: FIG. 9) is performed once again and the process returns to the adjustment of the ink pressure, etc. in FIG. 10a.

When the detected ink pressure P is less than the upper limit threshold Pa,
Since the ink viscosity is within the appropriate range and there is no need to supply diluent, set (update) the calculated Pvd to the pump driver 21 as an output (39) and set the T3 timer.
0), wait for the time to elapse (53), and when the time elapses, proceed to the phase search (9) in FIG. 9, and then return to the ink viscosity adjustment once that is completed. Note that T3 is the time from when the pump energizing pulse width is changed until the ink pressure in the head 5 stabilizes to the pressure determined by the change.

Vpd = Vpd - A Vpd (47)
and Vpd with P vts (56), Vpd is P
If it is less than ut-s, the energizing pulse width is within the predetermined range, so the calculated Pvd is set (updated) to the pump driver 21 (39), and the T3 timer is set (4o).
), wait for the time to elapse (53), and when the time elapses, proceed to the phase search (9) in FIG. 9, and after completing that, return to ink viscosity adjustment.

Calculate V pd = V pd - ΔVpd and convert Vpd to P
As a result of comparison with wts (56), Vpd is P wts
If it is less than the predetermined range, the energizing pulse width is outside the predetermined range on the short side, and ink ejection that brings about the set speed Cs cannot be performed, so the set speed Cs is updated to a value one step lower (49). As a result, the target flight speed is set one step higher (the time is set one step shorter).

Next, set the T3 timer (50), wait for timeout (51), and when the timer expires, phase search (9) in Figure 9 is performed.
), and when finished, return to adjusting the ink pressure, etc.

With the ink pressure adjustment of the ink pressure etc. adjustment explained above, standard data (count value equivalent to 13 m5ec) is given to the pump driver 21 as Vpd at the time of the first ink pressure adjustment, but after that, the ink pressure adjustment is performed. New data calculated based on speed detection is given as Vpd. If the deviation Cc is large, the correction value ΔVpd is large, so as the above-mentioned ink pressure adjustment is repeated, the deviation Cc is initially large, but later on, the deviation becomes smaller in a geometric progression, and rapidly falls within the extremely small error range. Converge. Therefore, the time from the start to the end of ink pressure adjustment is shortened, and the convergence error Cc at the end can be made extremely small. After adjusting the ink pressure, etc., the ink pressure is referenced, and if the ink pressure is outside a predetermined upper limit determined by the ink temperature, a diluent is supplied to the ink and the ink viscosity is lowered. The time it takes for the ink viscosity to become uniform after supplying the diluent, which is reduced to a level that can provide the required ink velocity through adjustment, is extremely short because the ink tank 13 is driven back and forth by the carriage.

Next, recording control (12) will be explained. In recording control, the microprocessor 31 keeps the AND gate All off and the timing pulse generator 20 reset (R27=L). As a result, the output of the OR gate R4 of the gate circuit 28 is maintained at a low level L during recording control, and only the output of the AND gate AO-A9 is applied to the D/A converter 28a. Microprocessor 31 then instructs deflection voltage generation circuit 27 to generate a deflection voltage. As a result, a predetermined constant high voltage is applied to the deflection electrode 7.

A reset signal is given to the charge code generator 22d immediately before sending out one character of printing data. When the charge code generator 22d receives the reset signal, it clears the count value and starts counting up from zero. The count pulse is 100 KH output by the pulse generator 19.
This is the pulse of z. The count code is an AND gate AO to A only when the printing data is at a high level H (recording instruction).
Output on 9.

This is the output CHP (a~h
Any one of the data selectors 22c, 23
(identified by the 3-bit code given in b)
is applied to the D/A converter 28a through the AND gates AO to A9 while the signal is at a high level H.

The signal CHP output by the data selector 22c is.

Signal 5P confirmed by phase search to charge ink
(Among a"h, those specified by the 3-bit code currently set to be output to the data selectors 22c and 23b)
The H pulse section was set approximately at the center. Since the H pulse period is eight times as long as the H pulse period, the recording charging pulse voltage applied to the charging electrode 6 is a relatively wide pulse extending from immediately before the ink separates into particles to immediately after 5 minutes. width, and the ink droplets are ensured by the charge code generator 2
2d to a level corresponding to the output code. While flying between the deflection electrodes, the charged ink particles are deflected by an amount corresponding to the charge they have and collide with the recording paper 8. The uncharged ink particles travel straight and collide with the gutter 9, pass through the ground filter 11, and are sucked into the pump 12.

In this embodiment, as explained above, the ink tank 13 is mounted on a carriage, and when supplying diluted liquid, the carriage moves back and forth to disturb the ink in the ink tank, so that the ink viscosity becomes uniform at an early stage, and recording control is controlled. The time it takes to enter is shorter than before.

In addition, first, by phase search, the phase of the charging signal is determined at the timing to reliably charge the ink particles; by adjusting the ink viscosity,
The pump energizing pulse width is controlled so that the ink flying speed reaches a set target value Cs, and when the ink pressure exceeds the upper limit determined by the ink temperature, a diluent is supplied to the ink to set the ink flying speed to the desired value. ; Then, recording charging is performed. In this way, the ink viscosity is kept below the set value, the ink flying speed is kept constant at the target value, the ink particles are reliably and stably formed, and the charge is reliably determined, so that the printing quality is extremely high.

Since the pump energizing parameter is changed in accordance with the deviation between the ink droplet flying speed and the target value, the ink flying speed is adjusted in a geometric progression, and the time required to set the target value is short.

In adjusting the ink pressure and searching for the phase, the deflection voltage is cut off, the charged ink particles are also allowed to advance straight, and are captured by the gutter, and the charges on the ink particles are detected. In printing, a deflection voltage is applied to a deflection electrode to deflect charged ink particles toward recording paper, and uncharged ink particles are captured by a gutter.

In this way, one conductive gutter is commonly used for three purposes: two-phase search for detecting ink flying speed, and capturing non-printing ink particles during recording and printing, so more than one explanation is required. As can be seen from the figure, the mechanical and electrical configurations of the inkjet recording apparatus are both simple. in spite of,
Both the detection of the ink flying speed and the phase search are reliable and stable.

The gutter 9 is easily soiled by ink splashes that collide with it, but since the core wire of the shielded wire 10 in the charge detection circuit 30 is grounded to the device through a resistor 30a, the ink recovery path is located at a predetermined position (filter 11). Since the equipment is grounded, charge detection is reliable even if the resistance value fluctuates due to ink stains on the gutter.

The flight speed is constant by controlling the energization pulse width of pump 1,
Further, since the ink particle size is controlled to be below a predetermined value by adjusting the viscosity, the particle size of the ink is stabilized and the printing quality is stabilized.

Next, another embodiment of the present invention will be described.

In the above embodiment, the ink jet nozzle and the unevenness of the ink tank are used as the swing means, but as shown in FIG. 1c, the ink tank may be provided with a vibration means (13c). The ink tank may be provided with a circulation pump, a screw driven by a motor, a vibrator, etc. as a swinging means, without being mounted on the carriage, or with the ink tank being mounted thereon.

On the other hand, in the above embodiment, the ink pressure upper limit value Pm corresponding to the ink temperature is stored in the memory in advance, and the value associated with the detected ink temperature is read out from the memory, and the detected ink pressure P is set to this value. I'm trying to compare it, but
When controlling the ink temperature at a constant temperature, this ink pressure upper limit value is stored as one fixed value, and the detected ink pressure P is compared with this upper limit value. In this case, the data selector 42 and temperature detection circuit 41 are omitted in FIG. 2, and the output data of the pressure detection circuit 41 is directly transferred to the printing control device
Give to 9. The ink jet head 5 further includes a heater 43 as shown in FIG.
3 and the temperature sensor 18 in a temperature control circuit 44 shown in FIG.
Connect to.

The temperature control circuit 44 amplifies the voltage of the temperature sensor 18,
This is compared with a voltage corresponding to the set temperature using a comparator, and if the detected temperature is lower than the set temperature, the transistor 44c is turned off, the transistor 44d is turned on, and the heater 43 is energized.

When the detected temperature exceeds the set temperature, the transistor 44c
is turned on, the transistor 44d is turned off, and the heater 43 is turned on.
Cut off the electricity.

In the above embodiment, the flight speed of the ink droplets is detected and compared with a set value, and the ink pressure is controlled so that the flight speed of the ink droplets matches the set value.The ink pressure is detected and the ink viscosity is controlled. is detected, but is equipped with a known deflection amount detection means,
The ink viscosity may be detected by detecting the amount of deflection of the ink droplets and controlling the ink pressure so that the amount becomes a set value. Alternatively, the ink viscosity may be detected by using other conventionally known viscosity detection means. May be detected. Furthermore, the patent application 1986-11
As disclosed in No. 2313, the control parameter (discharge pressure influencing parameter) of the pressurizing pump is changed so that the flying speed of ink is detected and becomes a predetermined value.

The ink viscosity may be detected based on the value of the parameter.

■Effects In any case, according to the present invention, when the diluent is supplied to the ink tank, the ink tank is rocked to promote mixing of the diluent and ink, so that the ink viscosity in the ink circulation system is made uniform. speed, and the operating efficiency of the recording device increases accordingly.

[Brief explanation of the drawing]

FIG. 1a is a side view showing an outline of an ink processing system according to an embodiment of the present invention, and a portion thereof is shown in cross section. FIG. 1b is a longitudinal sectional view of the ink jet head 5 shown in FIG. 1a. FIG. 1c is a sectional view showing the structure inside the ink tank in another embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of the electrical system of the embodiment shown in FIG. 1a. 3a and 3b are electrical circuit diagrams showing the configuration of a part of the electrical system elements shown in FIG. 2. FIG. FIG. 4 is an electric circuit diagram showing the configuration of another part of the electrical system elements shown in FIG. 2. FIG. 5 is a time chart showing the output signals of the recording charge signal generator 22 shown in FIG. 3a. FIG. 6 shows the timing pulse generator 20 shown in FIG. 3a.
3 is a time chart showing the output signals of the people in FIG. 7a and 7b are time charts for explaining the operating characteristics of the pump 1. FIG. FIG. 8 is an electric circuit diagram showing the configuration of another part of the electrical system elements shown in FIG. 2. FIG. 9 is a flowchart showing an overview of the control operation of the microprocessor 31 shown in FIG. 10a and 10b are flowcharts showing the ink pressure adjustment control operation of the microprocessor 31 shown in FIG. 2, and FIG. 11 is a flowchart showing interrupt processing in adjusting the ink pressure etc. FIG. 12a is a graph showing the relationship between the total ink ejection time and ink viscosity, and FIG. 12b is a graph showing the relationship between ink viscosity and ink flying speed. Figure 12c is a graph showing the relationship between ink temperature and ink viscosity; Figure 12d is a graph showing the relationship between pump energization pulse width and ink viscosity when the ink flying speed is constant;
FIG. 12e is a graph showing the relationship between the evaporation rate of water in the ink and the ink pressure required to set the ink flight speed to a predetermined value. FIG. 13 is a graph showing the relationship between the ambient temperature of the apparatus and the ink pressure required to set the ink flight speed to a predetermined value when the ink temperature is kept constant. FIG. 14 is a longitudinal sectional view of an ink jet head used in another embodiment of the present invention, and FIG. 15 is an electric circuit diagram showing an ink temperature control circuit used in this embodiment. 3.11: Filter 4: Solenoid switching valve 5: Ink jet head 6: Charging electrode 7: Deflection electrode 8
: Recording paper 9: Conductive gutter 10 = Shield wire 13: Ink tank 13C: Vibrating member carriage (oscillating means) 1
3d guide par 15: Cartridge 14: Electromagnetic on-off valve 16.17: Electrode for detecting remaining ink amount 18: Thermistor (temperature sensor) 29: Printing control device (ink pressure and viscosity control means)

Claims (4)

[Claims] (1) An ink ejection head equipped with an ink ejection nozzle and a vibrator that applies periodic pressure vibrations to ink in an ink chamber communicating with the ink ejection nozzle: A pressure pump that supplies ink in an ink tank under pressure to the ink ejection head: Charging electrode that applies a charging electric field to the ink ejected from the nozzle: Charging voltage generating means that applies a charging voltage to the charging electrode: Deflection electrode that applies a deflection electric field to charged ink particles: Deflection voltage generating means that applies a deflection voltage to the deflection electrode: and a gutter disposed between the deflection electrode and the recording paper to capture non-printed ink particles and return them to the ink tank: an ink dilution liquid storage container: supplying the ink dilution liquid in the ink dilution liquid storage container to the ink tank; In a deflection control inkjet recording apparatus comprising: a diluent supply means: a means for detecting the viscosity of the ink; and a dilution supply control means for instructing the dilution supply means to supply the dilution liquid at a high detected viscosity; the ink tank; A deflection control inkjet recording apparatus comprising: a swinging means for giving swinging motion to the ink; and a swinging control means for energizing the swinging means when a diluent is supplied. (2) The deflection control inkjet recording apparatus according to claim (1), wherein the swinging means is a carriage on which the inkjet head is mounted. (3) The deflection control ink jet recording apparatus according to claim 2, wherein the ink tank has at least one of a convex wall projecting into the inner space and a concave wall expanding the inner space. (4) The deflection control inkjet recording apparatus according to claim (2), wherein the ink tank has a vibrating body in an inner space that vibrates within the ink chamber space due to the rocking of the ink tank.