JPS61263761A - Charging control type ink jet recorder - Google Patents

Abstract

PURPOSE:To enable the dot diameter to be modulated, by a method wherein an ink drip of a large diameter and that of a small diameter are alternately generated during one cycle in which an ink column jetted from a nozzle is cut into ink drips and the respective large and small ink drips are individually charged according to a printing signal. CONSTITUTION:The ink pressurized in a pressure pomp 7 is fed to an ink jet head 1 with being excited in an exciter circuit 12, resulting that an ink column 19 jetted from the head 1 is cut into ink drips of large diameter 20, i.e., main drips, and that of small diameter 21, i.e. satellites. The jetted ink drips are charged by a charging electrode 2. At this time, the charging pulse has a cycle at most not more than 1/2 of a excitation cycle in order to charge two drips in a cycle and also enables each ink drip to be charged separately. The timing to charge the ink drips is obtained by a procedure in which the cutting phases for the satellites and the main drips are retrieved during the test of the charging phase retrieval and the retrieved cutting phases are stored to produce the charging pulse which is applied to the charging electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a charge control type inkjet recording device, more specifically, a charge control type inkjet recording device that enables a change in dot diameter, which has conventionally been considered difficult in a charge control type inkjet recording device. Controlled inkjet'v! , @Regarding the device.

Ink under pressure of one order of magnitude is supplied to a nozzle, and mechanical vibrations of a certain thickness are applied such that the ink particles are alternately separated into large diameter ink particles and small diameter ink particles at the tip of the ink column ejected from the nozzle. Inkjet recording apparatuses are known in which only small-diameter ink particles necessary for recording are applied to the ink and adhered to the recording medium based on electrical signals for recording (Japanese Patent Publication No. 57-46432, Japanese Patent Publication No. 58 18908), the above inkjet recording apparatus uses only small-diameter ink droplets for recording, and pixel diameter modulation cannot be performed depending on the inkjet recording apparatus.

Purpose The present invention was made in view of the above-mentioned circumstances.
In particular, this technique was developed with the aim of effectively using two types of ink particles, large and small, to modulate the pixel diameter.

Toyo-Ichiizumi In order to achieve the above-mentioned object, the present invention determines the size of large-diameter ink droplets and small-diameter ink droplets during one cycle of cutting an ink column ejected from a nozzle into ink droplets. This method is characterized in that two ink droplets of different sizes are generated alternately, and each of the large and small ink droplets is charged independently according to a print signal. An explanation will be given below based on one embodiment of the present invention.

FIG. 1 is a configuration diagram for explaining one embodiment of the present invention, and in FIG. 1, numeral 1 indicates an inkjet ejection head.

2 is a charging electrode, 3 is a deflection electrode, 4 is a gutter, 5 is an ink collection pump, 6 is an ink tank, 7 is an ink pressure pump, 8 is a valve, 9 is a recording paper, 10 is a charge detection circuit, 11 is a phase A control circuit, 12 an excitation circuit, 13 a distortion correction table,
14 is a print signal generation circuit.

15. 16 is an amplifier; 17 is a changeover switch for switching between printing mode and charge phase search mode; 18 is a deflection voltage circuit; 19 is an ink column; 20 is a large-diameter ink drop; 21
is a small-diameter ink droplet, which supplies ink pressurized by the pressure pump 7 to the inkjet ejection head 1, and is excited by the excitation circuit 12 to cut the ink column 19 ejected from the head 1 into ink droplets. , At this time, a large-diameter ink droplet 20 and a small-diameter ink droplet 21 are created. The large-diameter ink droplets 20 are called the main ink droplets, and the small-diameter ink droplets are called the satellites. Next, a charging electrode 2 is applied to the ink droplet jetted as described above.
In this case, in order to charge two droplets in one period, the period of the charging pulse is at least 1/2 or less of one excitation period, so that each droplet can be charged independently.

Here, regarding the timing of charging, during the charge phase search test, the cutting phase of the satellite and the main character is searched, the phase is memorized, and a charging pulse is generated to be applied to the charging electrode.

FIG. 2 is a diagram showing the cutting state of a continuous flow type ink droplet.
A) The figure shows an ink droplet when the excitation voltage is low, and (
B) The figure shows ink droplets when the excitation voltage is increased.
The cutting phase is the one in which the satellite 21 cuts after the main character 20 cuts, as shown in (A), and (B)
As shown in the figure, the whole 23 is cut, and then this whole 2
In the case where the satellite 23' is separated from 3, it is not said that two drops are created here.In addition, as shown in figure (A), the state where the satellite is located between the leading and the leading is called a constant velocity satellite. However, at that time, the cutting phase was shifted by about 180°, and the satellite was cutting in the middle between the leading and leading positions.

Therefore, when searching for one phase.

When the charge amount of the charged ink droplet is detected by the charge detection circuit 1o, the output is as high as Vl when the main character is detected, and as low as 2 when the satellite is detected, as shown in FIG. Now, when the excitation period is T.

If the satellite shift is tl, then tt /TX
It is said that the phase is delayed by 36 degrees.

FIG. 4 is a diagram showing an example of how the ink jetted as described above is applied. When the ink is applied as shown, the time taken to reach the main recording paper 9 as shown in FIG. Tm, the arrival time of the satellite is Ts, the recording paper moving speed Vi,
Deflection height xl for main character, x2 for satellite
Then, the delay time Z is I Z = -Ts -Tm, and printing must be performed with a delay of time 2.

Therefore, if we now press Q1 in the first column of Fig. 4, the printing signal will be as shown in Fig. 6(a), and the cutting phases that can be known in advance are as shown in Fig. 6(b), ( The phase becomes c).

Next, the relationship between the satellite charge signal and the main charge signal is as shown in Figure 6 (d) and (e), and the delay amount is Z, so the main charge signal must also be delayed, and finally becomes a charging pulse as shown in FIG. 6(f), and is charged by this pulse. However, since the satellite has small kinetic energy and high deflection efficiency, the charging voltage is lower than that of the main star. Here, merging of droplets and deviation of the printing position occur depending on the amount of charge, but this is corrected by using the charging voltage using a distortion correction table.

Figure 7 is a diagram showing the usage area, where A is the no-satellite area, B is the usage area, and C is the constant velocity satellite. As shown in the figure, when λ/8 is increased, the non-satellite area disappears and the area used here increases, so λ/8 is used between 5.5 and 6.0.

As is clear from the above description, according to the present invention, it is possible to perform pixel diameter modulation, which has conventionally been considered difficult in charge control type inkjet recording apparatuses.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram for explaining one embodiment of the present invention.
Fig. 2 shows an example of ink droplet ejection, Fig. 3 shows a charge detection voltage, Fig. 4 shows an example of printing, and Fig. 5 shows the printing relationship between main information and satellites. FIG. 6 is a diagram for explaining an example of a charging pulse.
FIG. 7 is a diagram for explaining an example of a usage area. DESCRIPTION OF SYMBOLS 1... Inkjet ejection head, 2... Charge electrode, 3... Deflection electrode, 4... Gutter, 5... Ink recovery pump, 6... Ink tank, 7... Ink pressure pump. 8... Valve, 9... Recording paper, 1o... Charge detection circuit, 11... Phase control circuit, 12... Excitation circuit, 13
...Distortion correction table, 14...Print signal generation circuit,
15.16... Amplifier, 17... Changeover switch, 18... Deflection voltage circuit, 19... Ink column, 20
...Large diameter ink droplet, 21...Small diameter ink droplet. Figure 1 1M Figure 2 Figure 3 Figure 4 Figure 7 Figure 6

Claims (3)

[Claims] (1) During one cycle of cutting the ink column ejected from the nozzle into ink droplets, two ink droplets of different sizes, a large diameter ink droplet and a small diameter ink droplet, are alternately generated. , a charge control type inkjet recording device characterized in that each large and small ink droplet is charged independently according to a print signal. (2) The charge control type according to claim (1), characterized in that the phase of generation of the two droplets is such that a small ink droplet is delayed by 180 degrees or more with respect to a large ink droplet. Inkjet recording device. (3) Detect the generation phase of the two drops, and calculate the phase difference between the phase with a large output and the phase with a small output by 90° to 2
Claim No. (1) characterized in that the angle is 70°.
The charge control type inkjet recording device according to 2.