JPS6233077B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a phase matching device for an inkjet recording device, and more particularly to a phase matching device for controlling charging timing in a charge control type inkjet recording device for high-frequency printing, for example. .

In recent years, inkjet recording devices have been increasingly used as computer output terminals or as devices for directly printing dates, serial numbers, etc. on products during the production process because of their ability to perform non-contact, high-speed printing. This device supplies ink under pressure to a nozzle, vibrates the ink at a constant frequency to turn the ink into particles, and at this time, the particles are appropriately charged and electrically deflected.
A predetermined pattern is recorded on a recorded object. The difficulty here is that the timing of particle formation changes depending on temperature, pressure, etc.
The question is how to adapt to this.

This will be explained in detail using FIGS. 1 to 4.

Here, FIG. 1 is an electrical system block diagram of a charge-controlled inkjet recording device, FIG. 2 is a partial circuit diagram of its phase matching device, and FIG. 3 is a diagram showing the relationship between an excitation signal and a phase detection signal. Timing Flow Chart FIG. 4 is a timing flow chart explaining what is shown in FIG.

First, in FIG. 1, when the output of the crystal oscillator 13 is applied to the vibrator 2 installed in the nozzle 1 through the amplifier 9, the pressurized ink in the nozzle 1 is ejected and becomes particles. Particle formation is performed in synchronization with the excitation frequency of the vibrator 2, and when the output of the charging signal generation circuit 14 is applied to the charging electrode 4 through the amplifier 10 in accordance with this, the ink particles 3 are charged. The charged ink particles 3 are deflected by a deflection electrode 5 connected to a high-voltage power source 11 according to the amount of charge, and reach a predetermined position on the recording material 7 . Note that the vibrator 2 is constantly excited and the ink particles 3 are continuously created, but the ink particles 3 that do not contribute to recording are not charged and are not deflected.
It is designed to be collected in gutter 6.

In FIG. 1, 8 is a sensor, 12 is a sensor amplifier, and 15 is a phase matching circuit.

Next, in the timing flowchart of FIG. 3, since the ink particle formation is synchronized with the excitation frequency, one ink particle 3 is created during one cycle T. The ink particles 3 are charged when they are formed into particles, but in order to perform accurate recording, the charging signal must be at the maximum value when they are formed into particles.

Therefore, as the phase detection signal of the charging signal, the pulse width is shorter than the excitation period T (in this example, 1/
2) Determine the optimal phase of the charging signal by shifting the signal by 1/n of T with respect to the excitation signal phase n times (n = 8 in this example) (Q ₁ to Q _o ) It is something to do.

The phase detection signals Q ₁ to Q _o are applied to the ink droplets 3 from the charging electrode 4 , the amount of charge on the ink droplets 3 is detected by the sensor 8 , and amplified by the sensor amplifier 12 to a required voltage level. This voltage level is processed by the phase matching circuit 15 and the optimum phase is input to the charging signal generation circuit 14.

In FIG. 2, which is a circuit diagram of the phase matching circuit 15, the voltage signal amplified by the sensor amplifier 12 is connected to a resistor 20 (resistance value R1Ω), a diode 21, a capacitor 22 (capacitance C1F),
It is input to the A/D converter 24 through a smoothing circuit composed of a resistor 23 (resistance value R2Ω), and this A/D
The data converted by the D converter 24 is input to the data processing circuit 25.
outputs the optimal phase.

Normally, the phase determination signal related to the phase detection signal input to the A/D converter 24 is as indicated by A1 in FIG. 4.

Now, assuming that the particle generation location is at the timing shown in FIG. 3, the phase determination signal A1 changes from 1 to 0 between phase Q ₂ and phase Q ₃ . Therefore, if the data processing circuit 25 recognizes this phase as the ink droplet generation phase and determines the phase of the charging signal, the ink droplets 3 can be charged in an optimal state.

As explained above, phase matching of charging signals is performed, but in the conventional phase matching circuit shown in FIG. 2, the values of resistors 20, 23 and capacitor 22 greatly affect phase detection. That is, the pulse signal of each phase is smoothed by charging with time constant C1R1 and discharging with time constant C1R2, and the charging time by C1R1 is equal to the rising time tc of the A1 waveform, and the discharging time by C1R2 is equal to the falling time. Directly affects time td.

In order to reduce ripples and improve smoothness of the phase determination signal as indicated by A2 in FIG.
1, R2, C1 are increased, C1R1, C1R
It is possible to increase the time constant of 2, but the times td and tc become large, making accurate phase determination impossible. Also,
In order to perform accurate phase determination, C1R1, C1R
If the time constant of 2 is made smaller, the ripple becomes larger, and as shown in A3, if the voltage level decreases due to the sensor 8 becoming dirty with ink, the level The judgment becomes unstable.

Even if a method is adopted in which the reference voltage Vs is optimally varied according to the level, if the S/N decreases, the level determination becomes unstable as in A4.

For the above-mentioned reasons, conventional circuits have dealt with this by increasing the time constant, reducing ripples, and increasing the phase detection signal time t _H for one phase.

However, since phase detection is not performed during printing because the detection signal becomes noise with respect to the print signal, there is a drawback that phase determination cannot be performed when high-speed printing or high-frequency printing is performed.

An object of the present invention is to provide a phase matching device for an inkjet recording device that solves the above-mentioned drawbacks of the conventional device by capturing a phase determination signal accurately at a stable level and at high speed. It is something to do.

The key point of the present invention is to reduce the ripples in the phase determination signal, and to quickly determine the signal level according to the charging status of the ink, making it independent of the time constant of the smoothing element. This is designed to detect the phase accurately and at high speed.

According to the above, the present invention is characterized by means for applying a charging signal to the ink particles by shifting the phase thereof at regular intervals for searching the separation phase of the ink particles, and the amount of charge of the ink droplet group at each phase. , a smoothing means having a capacitor for smoothing a detection signal outputted from the charge amount detection means, and a binarization means for converting the smoothed detection signal into a binary value. In a phase matching device for a charge control type inkjet recording device, which detects the charged state of ink particles by the output of the converting means and corrects the phase relationship between the separation phase of the ink particles and the recording charge signal, The time constant of the charging circuit is made small and the time constant of the discharging circuit is made large, and a semiconductor switching element is connected between the terminals of the capacitor to rapidly discharge the charge of the capacitor, and this semiconductor switching element is used to separate ink particles. The electric charge in the capacitor is rapidly discharged by conducting it periodically in synchronization with the phase shift timing of the charging signal for phase search, and the ink particles are detected by the binary output of the smoothed detection signal immediately before the discharge. A phase matching device for an inkjet recording device is configured to detect the charging state of an inkjet recording device.

Next, embodiments according to the present invention are shown in FIGS. 5 to 7.
This will be explained using figures.

Here, FIG. 5 is a partial circuit diagram of a phase matching device according to one embodiment of the present invention, FIG. 6 is a partial circuit diagram of a phase matching device according to another embodiment, and FIG. 7 is a partial circuit diagram of a phase matching device according to another embodiment. FIG. 7 is a timing flowchart for explaining what is shown in FIGS. 5 and 6; FIG.

In the figures, the same reference numerals as those in the preceding figures 1 to 4 indicate equivalent parts, and 30 is
A transistor related to a switching element, 31 a base resistor, 32 a switching timing circuit,
33 is a comparator.

That is, as in the conventional apparatus described above, ink particles charged by the n-phase (n=8 in this embodiment) phase detection signal are detected by the sensor 8, amplified by the sensor amplifier 12, and Resistors 20, 23 (resistance values R1, R2), capacitor 2
2 (capacitance C1) and a smoothing circuit composed of a diode 21, the signal is input to the A/D converter 24.

The difference from the previous conventional circuit is that the A/D converter 2
A transistor 30 driven by a switching timing circuit 32 is connected to the input of No. 4.

Next, a description will be given of the unique effect of the transistor 30, which is related to this switching element, on an article related to a position alignment device used for high-frequency printing.

FIG. 7 of the timing flow chart shows the waveform of the phase determination signal with respect to the phase of the detection signal.

In the circuit shown in FIG. 5 described above, the resistance value R of the resistor 20 is
1 is made sufficiently small, and the resistance value R2 of the resistor 23 is made sufficiently large, so that the time constant C1R1 is small and the time constant C1
If the capacitance C1 of the capacitor 22 is determined so that R2 is large, the rise time tc of the phase determination signal will be shortened as shown by B1, and the discharging time will be reduced because the time constant C1R2 is large. , the ripple decreases.

In the conventional circuit, when C1R2 is large, the discharge time becomes longer and the fall time td becomes longer. However, at this rising time, the switching timing circuit 32 controls the base resistor 31 at the timing of the phase change as shown in B3. through transistor 30
When switching , the fall occurs instantaneously as shown by B1.

As shown by the black dot 40 in the A/D conversion value data for signal judgment, if the data immediately before the pulse of switching timing B3 is used, very stable data with respect to the judgment reference value Vs can be obtained by changing the time constant. The phase detection signal _tH for one phase can be shortened, so high speed,
This enables high-frequency printing.

Next, the embodiment shown in FIG. 6 is an embodiment of a phase matching device circuit in which a comparator 33 is used in place of the A/D converter 24 for detecting the phase determination level.

The phase determination signal is indicated by B2 in FIG. 7, and is the same as the embodiment shown in FIG. 5 described above.

This phase determination signal B2 is input to the comparator 33 and compared with the reference voltage V _B input to the other terminal, and outputs a signal indicated by B4.

The data processing circuit 25 processes the data immediately before the phase change, the black dot 50, as the level of each phase.

As mentioned above, in this example, the previous circuit uses a comparator because it can be replaced with a comparator, and since the comparator is cheaper than the A/D converter used in the circuit shown in Fig. 5, it is inexpensive. It is possible to configure the device.

Note that the above points do not preclude the use of other means that perform the same function in addition to the A/D converter or comparator.

In summary, according to the present invention, ripples in the phase determination signal are reduced and the signal level responds instantaneously to changes in phase, making level determination accurate, stable, and fast. It is possible to charge ink particles at an optimal phase at all times even for high-speed printing and high-frequency printing.

Also, against ink stains on the sensor surface,
Because the information transferability of the phase detection signal is improved, it is possible to effectively perform abnormality judgment processing for detecting conditions around the nozzle (high pressure leaks, etc.) using the phase judgment signal, resulting in significant performance improvements. It is something that can be done.

Further, since the device according to the present invention can be configured only by adding low-cost switching elements such as transistors, it is highly economical and has great effects.

Based on the above, the present invention can be said to be an invention that eliminates the drawbacks of the prior art and has excellent practical effects.

[Brief explanation of the drawing]

Fig. 1 is an electrical system block diagram of a charge-controlled inkjet recording device, Fig. 2 is a partial circuit diagram of its phase matching device, and Fig. 3 is a timing flowchart showing the relationship between an excitation signal and a phase detection signal. 4 is a timing flowchart explaining what is shown in FIG. 2, FIG. 5 is a partial circuit diagram of a phase matching device according to an embodiment of the present invention, and FIG. 6 is a timing flow chart explaining what is shown in FIG. FIG. 7, a partial circuit diagram of the phase matching device according to the embodiment, is a timing flowchart for explaining what is shown in FIGS. 5 and 6. 1... Nozzle, 2... Vibrator, 4... Charged electrode, 5... Deflection electrode, 6... Gutter, 8... Sensor, 9, 10... Amplifier, 12... Sensor amplifier, 13... Crystal Oscillator, 14... Charge signal generation circuit, 15... Phase matching circuit, 20, 23...
Resistor, 22... Capacitor, 24... A/D converter, 25... Data processing circuit, 30... Transistor, 31... Base resistor, 32... Switch timing circuit, 33... Comparator.

Claims (1)

[Claims] 1 means for applying a charging signal to the ink particles by shifting the phase thereof at regular intervals for searching the separation phase of the ink particles; and charge amount detection means for detecting the amount of charge of the ink droplet group at each phase. , comprising a smoothing means having a capacitor for smoothing the detection signal output from the charge amount detection means and a binarization means for binarizing the smoothed detection signal,
In a phase matching device of a charge control type inkjet recording device, the charge state of the ink droplets is detected by the output of the value converting means, and the phase relationship between the separation phase of the ink droplets and the recording charge signal is corrected. The charging circuit has a small time constant and the discharging circuit has a large time constant, and a semiconductor switching element that rapidly discharges the charge of the capacitor is connected between the terminals of the capacitor. The charge in the capacitor is rapidly discharged by conducting it periodically in synchronization with the phase shift timing of the charging signal for separation phase search, and the ink is 1. A phase matching device for an inkjet recording device, characterized in that it is configured to detect the charged state of particles.