JPS593156B2 - Inkjet recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves ejecting ink subjected to ultrasonic vibration from a nozzle, selectively charging the ejected ink at a position where it separates into ink particles with a charging electrode, and deflecting the charged ink particles with an electrode. The present invention relates to an IC jet recording device that deflects the jet to collide with the recording paper.

This type of icjet recording device is already known (IMB Technical DisclOsureB).
ulletin2Ol・16ro12May1974, Special Publication No. 50-46450, etc.).

However, in this type of recording device, if the timing of the generation of ink particles and the application of the charging voltage (pulsed) to the charging electrode are misaligned, the amount of charge on the ink particles will not be as intended, and the printing on the recording paper will not be possible. Therefore, in the past, for example, Japanese Patent Publication No. 47-43450 and Japanese Patent Application Laid-Open No. 50-60
As disclosed in Japanese Patent No. 131 and the like, the timing of applying a charging voltage to a charging electrode is determined appropriately by searching for an appropriate charging phase of ink particles. However, in this case, although it is detected whether the charging is appropriate, it is not detected whether the ink particle size and deflection amount are appropriate, so even if the charging timing is correct, When the ink particle size is large, the recording density is high, and when the ink particle size is small, the recording density is low. Furthermore, if the amount of deflection is too large or too small, the image will shrink or expand, and since the recording paper is normally fed at a constant pitch or at a constant speed, the recorded image will also be disturbed. Generally, the amount of deflection Xd of ink particles is expressed by the following equation (1).

Qj・Dp Xd=K・・・・・・・・・・(1
)Mj-Sdp・J2 However, K゜Constant determined by the deflection electrode, Qj: Charge amount of the ink particle, Mj: Mass of the ink particle, Dp: Deflection voltage, Sdp: Electrode spacing of the deflection electrode, Vj: Ink particle The flight speed is .

As can be seen from this equation (1), the amount of deflection of ink particles Xd
Since it depends on many factors, it is not possible to know the amount of deflection by simply detecting the amount of charge, and therefore it is not possible to perform appropriate deflection control.

For example, even if the above-mentioned K, Vdp, and Sdp are constant (they can be easily maintained constant), and even if Qj can be controlled to an appropriate value by phase search, Mj and Vj exist as variable elements. In other words, the viscosity of the ink changes due to changes in the temperature of the ink liquid, resulting in changes in Vj and Mj, and the properties of the ink are slightly different when the ink is not replaced for a long time and immediately after the ink is replaced, resulting in Vj and Mj. M
j changes. Therefore, it is desirable not only to search for an appropriate charge phase through phase search to set QJ to an optimal value, but also to detect the amount of deflection and determine the appropriate amount of deflection. Also Mj
Since it is related to recording density, it is desirable to keep it constant. An object of the present invention is to keep the recording density constant and the amount of deflection of charged ink particles constant.

FIG. 1 shows an embodiment of the present invention.

In FIG. 1, 1 is an ink tank, 2 is a filter, 3 is a pump, 4 is an accumulator, 5 is an ink jet nozzle, and 7 is an ink tank.
8, 82 are charge detection electrodes, 9 is a deflection electrode, 10 is a backlash, and 11 is a recording paper. Ink in the ink tank 1 is sucked by a pump 3 through a filter 2 and enters an accumulator 4. Gas is sealed in the accumulator 4, and this gas absorbs the pulsation of the discharge pressure of the pump 3, so that ink is supplied to the nozzle 5 at a constant pressure and the ink is ejected from the nozzle 5. A charging electrode 7 is arranged at a position where this ejected ink separates into ink particles, and the charging electrode 7 is arranged in accordance with the timing of formation of the ink particles.
A charging voltage is applied to according to the printing signal. The ink particles thus charged are deflected by the electric field of the deflection electrode 9 and collide with the recording paper 11, while the uncharged ink particles travel straight and are captured by the gutter 10. The ink trapped in the gutter 10 also reaches the filter 2. A constant deflection voltage is always applied to the deflection electrode 9 from a deflection voltage power source 12 . An alternating current or pulsating current of a constant voltage and a constant frequency is applied from the amplifier 13 to the ultrasonic vibrator of the nozzle 5, and as a result, the ultrasonic vibrator of the nozzle 5 vibrates at that frequency, causing the ink in the nozzle to vibrate. Adds vibration. Due to this vibration, the ink column breaks in the charging electrode 7 portion, and ink particles are generated at a speed (number of particles of 1 sec) corresponding to the above frequency. The excitation reference wave is generated by an excitation signal generator 15 in synchronization with the clock pulses of a clock pulse oscillator 14. The clock pulse is also applied to charge signal generation circuit 16 and search signal generation circuit 17. Charge signal generation circuit 1
Reference numeral 6 generates a charging pulse whose wave height sequentially rises or falls step by step in synchronization with a clock pulse, and repeats this at a fixed period for each predetermined pulse. This stepwise change in wave height determines the printing position in the feeding direction of the recording paper (from top to bottom in FIG. 1, or vice versa: sub-scanning). The nozzles 5 to 10 are continuously driven to scan (main scan) from the back side of the page to the front side at a constant speed, and when they reach the end, they are returned to the starting end and are driven again in the main scan. The recording paper is fed by one line in the sub-scanning direction for each main scan. The output pulse of the charge signal generation circuit 16 is applied to the phase setting circuit 19 via the switching circuit 18.

In the recording mode, the phase setting circuit 19 adjusts the phase of the charging pulse to the phase set in the phase search mode and supplies it to the charging control circuit 20. , a search pulse with a constant peak value is given to the phase setting circuit via the switching circuit 18), the phase of the search pulse is sequentially shifted until an appropriate charge detection signal is obtained from the charge detection circuit 21. When the appropriate charge detection signal appears, the phase is fixed at that time, and when the search command signal arrives, one cycle of phase search operation is started. The charge control circuit 20 outputs a charge pulse to the amplifier 22 when there is an image signal, that is, when there is a signal representing printing, and when there is no image signal, the charge control circuit 20 cuts off the charge pulse and does not supply it to the amplifier 22. To summarize, in the recording mode, the switching circuit 18 applies a charging pulse to the phase setting circuit 19, the amount of deflection of ink droplets (in the sub-scanning direction) is determined by the peak value of the charging pulse, and the phase setting circuit 19 applies a charging pulse to the phase setting circuit 19. for,
The phase of the charging pulse is adjusted to the charging voltage phase for most appropriately charging the ink droplets, and the charging control circuit 20 determines whether printing is to be performed or not. In the phase search mode, the switching circuit 18 applies a search pulse to the phase setting circuit 19, and since the peak value of this pulse is constant, the amount of deflection of the ink particles is constant (provided that they are properly charged). , the phase setting circuit 19 sequentially shifts the phase of the charging pulse until the charge detection circuit 21 issues a proper charge detection signal, and then fixes the charge voltage phase to the phase at that time. The components and their operations described above have already been proposed.

Next, parts added based on the present invention will be explained. 6
, , 62 and 63 are first, second and third charge detection electrodes, respectively.

An enlarged perspective view of these is shown in FIG. 2a. 2nd and 3rd
A gap 25 is formed between the electrodes 62 and 63, and the width of the gap 25 is such that it allows ink particles flying along a certain deflection trajectory on the recording paper to pass therethrough, and the width of the gap 25 is set to a width that is permissible for the deflection trajectory. The deflection range is extremely narrow, allowing ink particles that fly with deviations within the specified error range to pass through, while ink particles with other deviations are blocked. In other words, in the front view shown in FIG. 2b, the width of the gap 25 is such that only the ink particles 1s (solid line) flying along the reference trajectory and the ink particles 1sa (dotted line) that are deviated from the reference trajectory within the allowable range Δd pass through. It is becoming. The second and third charge detection electrodes 62 and 63 are arranged in a direction perpendicular to the deflection direction (H-
As long as the ink droplet position setting (positioning in the main scanning direction) in H) can be performed accurately, it is preferable to tilt the ink droplet slightly with respect to the direction (H-H) perpendicular to the deflection direction, as shown in Fig. 2c. .

In this way, the ink swings along the deflection direction D-D, but the ink that collides with the second charge detection electrode 62 is
Since the ink particles flow to the left (FIG. 2c) along the slope, the ink particles are not obstructed when they try to pass through the gap 25. Referring again to FIG.

The ink that collides with the first, second and third charge detection electrodes 61, 62 and 63 falls into the gutter 24. These electrodes 6, - 63 and gutter 24 are arranged at the recording start position as shown in FIG. 3a (in this case, the recording paper 1
1 is moved to the recording position after the deflection amount setting is completed, and is placed in a position that does not interfere with normal recording, such as in the recording standby position as shown in FIG. 3b. The first charge detection electrode 6 has a first integration circuit 23.
1 is connected to the second charge detection electrode 6, and the second integration circuit 23 is connected to the second charge detection electrode 6.
2, and a third integration circuit 233 is connected to the third charge detection electrode 63. The first integrating circuit 23 includes a field effect transistor (FET) 23,a, an operational amplifier 231b, and an integrating capacitor 23,c. The second and third integrating circuits also have similar configurations. The outputs of the integrating circuits 231-233 are applied to differential amplifiers 261-263, respectively, and the reference voltage S1 is applied thereto.
~ S3 are compared respectively. Differential amplifiers 261-26
When the output voltages of the integrating circuits 231 to 233 exceed the reference voltage, the circuit 3 outputs a charge detection signal of high level "1" and supplies it to the level setting circuit (charge voltage level setting means) 28. The level setting circuit 28 controls the voltage adjustment ratio (ratio of output voltage level to input voltage level: gain) of the level adjustment circuit 27 inserted between the phase setting circuit 19 and the charge control circuit 20. The level adjustment circuit (charged voltage level adjustment means 27 is composed of a transistor 27a, an operational amplifier 27b, and a capacitor 27c, and the output voltage level changes depending on the base bias of the transistor 27a.The level setting circuit 28 includes a flip-flop 28a,
28h, AND gate 28b, 281, 28p1 OR gate 28c, 2811 up/down counter 28d, coincidence detection circuit 28e1 code generator 28f, digital-to-analog converter (hereinafter referred to as 5D/A converter) 28g1 switching circuit 28J. It is composed of a reference signal generator 28k and a frequency divider 28m.

The code generator 28f generates a count code corresponding to the reference gain of the level adjustment circuit 2r, and is, for example, an adjustable code generator (matrix circuit) consisting of a combination of resistors, diodes, and a code setting switch. is used. That is, the code generator 28f specifies the initial setting gain of the level adjustment circuit 27. That is, when a pulse representing power-on arrives at the level setting circuit 28, the flip-flop 28a is set, so that its Q output becomes "1" and the clock pulse (output of 14) is sent to the counter 28d through the AND gate 28b and the OR gate 28c. is applied to the count pulse input terminal CK of the flip-flop 28a.
(:!) Q output "1" is applied to the counter 28d through the OR gate 281 as an up-count designation signal. As a result, the counter 28d starts counting up, and when the count code becomes equal to the output code of the code generator 28f, the output of the coincidence detection circuit 28e becomes "1".
At this rising time, the flip-flop 28a is set and its Q output becomes "0", the AND gate 28b is turned off, and the clock pulse to the counter 28d is cut off. In this manner, the counter 28d is first cleared to zero when the power-on pulse arrives, then counts up until it reaches the output code of the code generator 28f, and then stops. Therefore, the D/A converter 28g applies an analog voltage corresponding to the code set in the code generator 28f to the base of the transistor 27a of the level adjustment circuit 27. Therefore, the above-mentioned phase search and setting is performed using the level adjustment circuit 27 as the reference gain (the code generator 28
(corresponding to the output code of f). Note that the coincidence detection circuit 28e is a combination of, for example, n exclusive NOR gates and one AND gate whose outputs are input, where n is the number of code digits, and each exclusive NOR gate has a counter 28d.
This is a combination that provides signals of corresponding digits of the output of the code generator 28f. When a pulse designating the deflection amount control arrives, the flip-flop 28h is set, and its Q output becomes "1", which is passed through the AND gate 281 and the OR gate 28c to the frequency divider 28m.
The output pulse of is applied to the count pulse input terminal of the counter 28d.

The frequency divider 28m divides the frequency of the clock pulse by, for example, 1/612, and in this case, one pulse is output every time 612 ink droplets are generated. Since the phase search has already been completed by the time the deflection amount control designation pulse arrives, the ink particles are charged, but the switching circuit 28j adjusts the level of the output pulse of the reference signal generator 28k by the flip-flop 28h0) Q output "1". circuit 2
7 operational amplifier 27b. This reference signal generator 2
8k is synchronized with the output charging pulse of the phase setting circuit 19,
Among these pulses, the pulse that should give the amount of deflection that passes between the electrodes 62 and 63 (a certain fixed peak value assigned to print the ink droplets at the pixel position in the width scanning direction on the recording paper) outputs a pulse with a constant peak value equal to the peak value of the pulse (pulse). Therefore, if ink is ejected as originally designed and under recording conditions that exactly match the conditions of equation (1) originally determined, all charged ink particles will pass through the gap between the electrodes 62 and 63. It should be done. Then, when it actually passes, the charge detection electrode 61
detects this, the output potential of the integrating circuit 231 rises,
By the time the frequency divider 28 outputs one pulse, the differential amplifier 261 has already become "1", and the flip-flop 28h is set at the rising edge of the pulse.The counter 28d does not count up or count down, and its output code is The output code remains the same as the output code of the device 28f (deflection amount adjustment completed). However, in general, the charged ink particles deviate from their predetermined trajectory and collide with the second or third charged detection electrode, thereby causing the output of the differential amplifier 262 or 26 to reach the output of the differential amplifier 262 or 26 by the time the frequency divider 28m outputs a pulse. is "1", and the counter 28d receives a down count command signal (2
62 output is “1”) or up count command (
When the output of H.263 is "1") is given. Therefore, when the frequency divider 28m outputs a pulse, the counter 2
8d counts down or up by 1.
As a result, the output voltage of the D/A converter 28g decreases or increases by one step, and the gain of the level adjustment circuit 27 is changed by one step. In this down-count or up-count operation, the output of the differential amplifier 26 is at a high level "1".
This continues until the flip-flop 28h is set, that is, until the charged ink particles pass through the gap between the charge detection electrodes 62 and 63. When the flip-flop 28h is reset, the AND gate 281 is turned off, so the count code of the counter 28d remains as it was at that time, and therefore the gain of the level adjustment circuit 27 is set to a constant value (adjustment that provides the desired amount of deflection). value), and the switching circuit 28j is the phase setting circuit 1.
The mode is switched to a mode in which the output of 9 is given to the level adjustment circuit 27 (deflection amount adjustment is completed). 30 is a speed detection circuit, which includes amplifiers 30a, 30a2 for amplification and waveform shaping, and R-S flip-flops 30b, . It is composed of a FET 30c1, an integrating capacitor 30d, comparators 30e, 30e2, and a NAND gate 30f.

Charge detection electrodes 81 and 82 are connected to the input ends of amplifiers 30a1 and 30a2, respectively. Therefore, when the charging phase setting is completed and the ink droplet is charged, the amplifier 30a outputs a pulse when the ink droplet passes the charge detection electrode 8, sets the flip-flop 30b, and the ink droplet is charged. When the voltage passes charge detection electrode 82, amplifier 30a2 outputs a pulse to reset flip-flop 30b. Therefore, the flip-flop 30b(7)Q output indicates that the ink particles are charged at the detection electrode 8.
, -82, the high level is "1". F
ET3Oc is turned on by this Q output of "1", conducts during this time, and provides a charging current to the capacitor 30d. Therefore, the charging voltage of the capacitor 30d is low when the flying speed of the ink particles is high, and becomes high when the flying speed is low, and corresponds to the flying speed. This charging voltage is determined by comparator 3
0e and 30e2 are compared with voltage S5 representing the upper speed limit and voltage VS6 representing the lower speed limit, respectively. When the charging voltage is S5, that is, when the flying speed of the ink particles exceeds the upper limit value, the output of the comparator 30e1 is "1", which is given to the pump drive circuit 29 as a deceleration command signal, and the charging voltage At S6, that is, when the flying speed of the ink particles is less than the lower limit value, the comparator 3
When the output of 062 is "1" and the acceleration command signal given to the pump drive circuit 29 is VS5≦charging voltage≦S6, that is, when the flying speed of the ink particles is within the appropriate range, the The output of the NAND gate 30f is "1" at the timing when the set signal B is high level "1",
It is given to the pump drive circuit 29 as a latch finger ◆ signal which fixes the current drive speed (pressure) from now on. The pump drive circuit 29 is configured to adjust the pump drive voltage, pump drive voltage period, trigger phase, pulse duty, etc., which are known in motor type or solenoid type pumps.
It controls parameters for speed control, sets the parameters to standard values in response to power-on, and drives the pump at the standard values until the search command signal is released. After the phase search, the pump pressure is controlled. In controlling the pump pressure, image signals are supplied to the charge control circuit 20 in a predetermined pattern, and in response to this, the speed detection circuit 30
A deceleration command, an acceleration command, or a latch command is generated, and the latch command is given to the pump drive circuit 29 at the timing when the set signal B is "1". The pump drive circuit 29 is
When a deceleration command arrives, the one-step parameter is shifted to the deceleration side, and when an acceleration command arrives, it is shifted one-step to the acceleration side. If the speed detection circuit 30 issues a deceleration command or an acceleration command after a predetermined time from the start of pump pressure control, the phase search will start again. Latch. In this way, phase search is performed every time the pump drive speed is changed by one step under pump pressure control. If the speed detection circuit 30 has not issued a deceleration command or an acceleration command after a predetermined time from the start of pump pressure control, a set signal B is given to the speed detection circuit, and the NAND gate 30f sends a latch command to the pump drive circuit 29. give, pump drive circuit 2
9 latches the driving speed at that time. Speed detection circuit 3
0 issues a latch command, the aforementioned deflection amount adjustment is started. Therefore, when the deflection amount control is completed,
The charging phase, ink flying speed, and deflection amount have all been set to predetermined values, and the discharge pressure of the pump 3 has become the predetermined value, so the mass and flying speed of the ink particles have reached the predetermined values, and the recording density has been adjusted. Then, ic jet recording is performed with an appropriate amount of deflection.

Furthermore, instead of controlling the amount of deflection of charged ink particles by controlling the charging voltage, the amount of deflection can also be controlled by controlling the deflection voltage.

In this case, for example, as shown in FIG. 4, in order to make the deflection voltage power supply circuit 12 a controllable power supply circuit,
A deflection voltage control circuit (deflection voltage level adjusting means) 40 may be inserted on this output voltage side, the level setting circuit 28 may be used as it is as the deflection voltage level setting means, and the output voltage may be used for control. The deflection voltage control circuit 40 is
It is composed of a coil 40b wound around the iron core of the transformer 12a of the deflection voltage power supply circuit 12, diodes 40C1 and 40C2, a smoothing capacitor 40d, a Zener diode 40e1, a transistor 40a and 40f1, a capacitor 40g, and a resistor. In this case, the transistor 40a
The collector voltage of the transistor 40a is maintained constant by the Zener diode 40e, and when the base voltage of the transistor 40a increases to the positive side, the conductivity of the transistor 40a increases and the conductivity of the transistor 40f decreases.
When the current value flowing through the coil 40b becomes smaller and the base voltage of the transistor 40a becomes lower, the conductivity of the transistor 40a decreases, the conductivity of the transistor 40f increases, and the value of the current flowing through the coil 40b increases. In the deflection voltage power supply circuit 12, when the current of the coil 40b, that is, the load current increases, the voltage drop due to the primary side resistor 12b increases, and the output voltage, that is, the deflection voltage drops.
When the current at 0b becomes smaller, the output voltage increases. In this way, increasing the base voltage of the transistor 40a increases the output voltage of the deflection voltage power supply circuit 12, and decreasing the base voltage decreases the output voltage. Therefore, the output voltage of the D/A converter 28g is applied to the deflection voltage control circuit 40, the level adjustment circuit 27 is omitted, and the phase setting circuit 1
9 to the charge control circuit 20, and the power supply circuit 12
By connecting one output end of the (FIG. 4) to one side of the deflection electrode 9 and grounding the other, the amount of deflection of the charged ink particles can be controlled by controlling the deflection voltage, as in the case of charge control. . In addition, in the above explanation, an example is given of a quick-jet recording device having one nozzle, but even when a plurality of nozzles are arranged for multi-use, there is a detection control unit not used for printing at the end of the nozzle array line. It is also possible to provide feedback control of the deflection amount and speed of ink droplets ejected from each nozzle.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2a is an enlarged stylus view of the charge detection electrodes 6, 6, shown therein, FIG. 2b is an enlarged front view, and FIG. 2c is the other one. 3A and 3B are front views showing the arrangement thereof. FIG. 4 is a circuit diagram showing a modified part of another embodiment of the present invention. 1...Ink tank, 2...Filter, 3...Pump, 4...Accumulator, 5...Nozzle, 6, ~63・・・・・・
Charged detection electrode, 7... Charged electrode, 8...
・Charge detection electrode, 9... Deflection electrode, 10, 24
... Gutter 11 ... Recording paper, 231
~233...Integrator circuit, 25...Gap, 27...Level adjustment circuit, 28...
...Level setting circuit, 30... Speed detection circuit,
40...Deflection voltage control circuit.

Claims (1)

[Scope of Claims] 1. An ink ejecting head including a vibrating element, a charging electrode, a deflection electrode, a pump supplying pressurized ink to the ink ejecting head, and circuit means for applying an excitation voltage of a constant frequency to the vibrating element. In an inkjet recording apparatus comprising a circuit means for applying a charging voltage to a charging electrode and a circuit means for applying a deflection voltage to a deflection electrode; A first charged detection electrode disposed in the flight path of charged ink particles, a narrow area through which only charged ink particles with a specific amount of deflection can pass among the charged ink particles with many deflections toward the first charged detection electrode. second and third charge detection electrodes arranged apart from each other to form a slit to prevent passage of charged ink particles having other deflection amounts; and connected to the first, second and third charge detection electrodes. An ink droplet deflection detection device comprising an integrator circuit; a speed detection means for detecting the speed of the flying ink droplets; an ink droplet action voltage indication signal is generated, and based on the detection signal of the deflection detection device, the charged ink droplets are When the charged ink particles are colliding with the second charge detection electrode, the ink droplet action voltage instruction signal is changed in a direction to reduce the amount of deflection of the charged ink particles, and when the charged ink particles are colliding with the third charge detection electrode, Feedback control that changes the ink droplet action voltage instruction signal in a direction to increase the amount of deflection of the charged ink droplet, and stops changing the ink droplet action voltage instruction signal when the charged ink droplet is colliding with the first charge detection electrode. means; working voltage setting means for setting the ink droplet working voltage according to the ink droplet working voltage instruction signal; and lowering the driving speed of the pump when the flying speed of the ink droplets is high according to the detection signal of the speed detecting means; An inkjet recording device comprising: pump energizing means for increasing the driving speed of the pump when the flying speed is low. 2. The ink droplet action voltage instruction signal is a charging voltage level adjustment signal; the feedback control means generates a charging voltage level adjustment signal, and based on the detection signal of the deflection detection device, the charged ink droplet is directed to the second charge detection electrode. When the charged ink particles are colliding with the third charge detection electrode, the charging voltage level adjustment signal is changed in the direction of lowering the charging voltage, and when the charged ink particles are colliding with the third charge detection electrode, the charging voltage level adjustment signal is changed in the direction of increasing the charging voltage. charging voltage level setting means for changing the charging voltage level adjustment signal and stopping changing the charging voltage level adjustment signal when the charged ink particles are colliding with the first charge detection electrode; The inkjet recording apparatus according to claim 1, further comprising charging voltage level adjusting means for determining the charging voltage level to be applied to the charging electrode. 3. The ink droplet action voltage instruction signal is a deflection voltage level adjustment signal; the feedback control means generates a deflection voltage level adjustment signal, and based on the detection signal of the deflection detection device, the charged ink droplet is applied to the second charge detection electrode. When the charged ink particles are colliding with the third charge detection electrode, the deflection voltage level adjustment signal is changed in the direction of decreasing the deflection voltage, and when the charged ink particles are colliding with the third charge detection electrode, the deflection voltage level adjustment signal is changed in the direction of increasing the deflection voltage. the deflection voltage level setting means that changes the deflection voltage level adjustment signal and stops changing the deflection voltage level adjustment signal when a charged ink particle is colliding with the first charge detection electrode; The inkjet recording apparatus according to claim 1, further comprising a deflection voltage level adjusting means for determining the deflection voltage level to be applied to the deflection electrode.