JP3133916B2 - Continuous ejection type ink jet recording apparatus and method for setting optimum excitation frequency - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous jet type ink jet recording apparatus, and more particularly to measuring the charging frequency characteristics of an ink jet by changing the excitation frequency (frequency of an excitation signal) of a vibrator mounted on a nozzle. Continuous ejection type ink jet recording apparatus for automatically determining and setting the optimum excitation frequency for optimizing the generation of satellite particles (fine particles compared to the main particles) and the stability of the particle formation phase, and its optimum excitation frequency Regarding the setting method.

[0002]

2. Description of the Related Art FIG. 10 is a block diagram showing a main part of a conventional continuous jet type ink jet recording apparatus. This continuous ejection type ink jet recording apparatus includes a nozzle 1 having a very small diameter circular orifice, an ink electrode 2 for setting the potential of the ink in the nozzle 1 to a ground level, and a vibrator comprising a piezoelectric vibrator mounted on the nozzle 1. 3, a control electrode 4 having a circular opening or a slit-shaped opening concentric with the nozzle 1 and to which a charge control signal for controlling charging of the ink jet is applied in accordance with image data; Right)
A ground electrode 5, a knife edge 6 attached to the ground electrode 5, a deflection power supply E 1, and a strong electric field orthogonal to the jet flight axis between the deflection power supply E 1 and the ground electrode 5. A deflection electrode 7 for deflecting the charged ink particles to the ground electrode 5 side; and a reference oscillator CG for generating a reference clock CLK having an oscillation frequency specified by a microprocessor unit (hereinafter abbreviated as MPU). A frequency divider FD for dividing the reference clock CLK by N (positive integer) to generate an excitation signal PCLK, and a phase obtained by delaying the excitation signal PCLK to N (positive integer) stages according to the reference clock CLK θ ₀ , θ ₁ , θ ₂ , ..., θ _N-1
Pulse generator DG that outputs excitation signal PCLK of
When the delayed phase _{θ 0, θ 1, θ 2} , ..., a multiplexer selects either the theta _N-1 of the excitation signal PCLK M
P and an oscillator driver V that drives the oscillator 3 with the excitation signal PCLK having the phase θ selected by the multiplexer MP.
D, a pulse width modulator PM for converting image data into a pulse width corresponding to a density gradation, and a rising or falling edge of an output of the pulse width modulator PM as a rising or falling edge of the excitation signal PCLK. Synchronizing circuit SC for synchronizing
And a high-voltage switch HVS for amplifying the output of the synchronization circuit SC and applying the amplified voltage to the control electrode 4 as a charging control signal. Note that the code DR is
4 shows a rotating drum around which a recording medium is wound.

In such a conventional continuous ejection type ink jet recording apparatus, the MPU variably sets the oscillation frequency of the reference clock CLK of the reference oscillator CG, so that the excitation frequency of the excitation signal PCLK is variably set. Was. The image quality depends on the particleization characteristics of the nozzle 1, and the particleization characteristics change according to the excitation frequency of the excitation signal PCLK. For this reason, in the conventional continuous ejection type ink jet recording apparatus, the test image is printed while changing the excitation frequency of the excitation signal PCLK and the image quality is visually checked, so that the optimum excitation frequency can be manually set from the outside (operation panel or the like). (Japanese Unexamined Patent Publication No.
220350).

[0004]

In the conventional continuous jet type ink jet recording apparatus described above, when the ink jet is split from the ink column to the ink particles, there are two problems in the splitting method.

[0005] The first problem is a problem of satellite particles generated between the main particles due to the non-linearity of the surface deformation of the ink column. The generation modes of the satellite particles include a mode in which the generated satellite particles unite with the subsequent main particles,
There are three modes: a mode in which the generated satellite particles are combined with the preceding main particles, and a mode in which the generated satellite particles are not combined until they reach the recording surface. In a continuous jet type ink jet recording apparatus, a mode in which satellite particles are not generated is most desirable. However, even if it is generated, there is no particular problem in the case where the particles are quickly combined in the control electrode 4. However, coalescence is slow and the control electrode 4
In the case of merging behind the exit near the exit or not merging to the recording surface, the charged satellite particles (typically, the specific charge is larger than the charged main particles) are strongly affected by the deflecting electric field and deflect before the charged main particles. As a result, the charged main particles exert electrostatic repulsion in a direction perpendicular to the jet flight axis, thereby escaping normal deflection of the charged main particles. Also, if the charged satellite particles deflect and deviate from their normal trajectories and merge with the recorded uncharged main particles, they will slightly deflect the uncharged main particles. All of these have greatly reduced the image quality. Hereinafter, this problem is referred to as a satellite particle problem.

The second problem is that the phase (timing) at which the ink column splits into ink particles with respect to the phase of the excitation signal PCLK is different and unstable for each ink particle. This slight variation in the particleization phase at the particleization point is amplified by the influence of air resistance during the flight of the ink particles, and appears as a large position fluctuation near or behind the knife edge 6. The phase of the charge control signal during printing is kept constant with reference to the phase of the excitation signal PCLK. If the particleization phase changes in this state, the charging phase cannot always be kept optimally, and the measurement of the optimum charging phase will also be erroneous. Such a jet is defined as a fuzzy jet. In the case of the fuzzy jet, the image quality is remarkably deteriorated similarly to the satellite particle problem due to the generation of half-charged ink particles due to the fluctuation of the ink particle position in the jet flight axis direction and the fluctuation of the charging phase.
Hereinafter, this problem is called a fuzzy jet problem.

The above two problems are empirically heavily dependent on the excitation frequency of the excitation signal PCLK. That is, it is considered that the vibration of the vibrator 3 mounted on the nozzle 1 depends on the frequency characteristics of the mechanical vibration system transmitted to the particleization point of the ink jet.

In order to solve these problems, in the conventional continuous ejection type ink jet recording apparatus, as described above, a test image is printed while changing the excitation frequency of the excitation signal PCLK, and the test image is visually checked and optimized. The excitation frequency was selected and manually set, so there is the complexity of having to actually print the test image.The excitation determined to be optimal is very ambiguous because the criterion is based on visual inspection of the image. There is a problem that the setting of the frequency is troublesome because it is manual.

A first object of the present invention is to enable the excitation frequency of a vibrator mounted on a nozzle to be variably adjusted, to measure a jet current waveform while changing the excitation frequency, and to characterize the measured jet current waveform. It is an object of the present invention to provide a continuous jet type ink jet recording apparatus in which an optimum excitation frequency is determined for a satellite particle problem and a fuzzy jet problem by performing extraction, and the frequency is automatically set to the frequency.

A second object of the present invention is to make it possible to variably adjust the excitation frequency of the vibrator for each nozzle in a color-printable continuous jet type ink jet recording apparatus equipped with a plurality of nozzles. A continuous injection type in which the jet current waveforms are measured in order for a plurality of nozzles, and the characteristic of each jet current waveform is extracted to determine the optimal excitation frequency and automatically set the excitation frequency. An object of the present invention is to provide an ink jet recording apparatus.

A third object of the present invention is to make it possible to variably adjust the excitation frequency of the vibrator common to each nozzle in a color-printable continuous jet ink jet recording apparatus equipped with a plurality of nozzles. A continuous ejection type ink jet that measures the jet current waveforms for multiple nozzles simultaneously, extracts the characteristics of each jet current waveform, determines the optimal excitation frequency, and automatically sets it to that excitation frequency. A recording device is provided.

A fourth object of the present invention is to measure the jet current waveform while changing the excitation frequency of the nozzle, and extract the characteristics of the measured jet current waveform, thereby reducing the satellite particle problem and the fuzzy jet. An object of the present invention is to provide an optimum excitation frequency setting method which determines an optimum excitation frequency for a problem and automatically sets the frequency to the optimum excitation frequency.

A fifth object of the present invention is to optimize the measurement by measuring the jet current waveform while sequentially changing the excitation frequency for a plurality of nozzles and extracting the characteristics of each measured jet current waveform. An object of the present invention is to provide an optimum excitation frequency setting method for determining an excitation frequency and automatically setting the excitation frequency to the determined excitation frequency.

A sixth object of the present invention is to optimize the excitation by measuring the jet current waveform while simultaneously changing the excitation frequency for a plurality of nozzles and extracting the characteristics of each measured jet current waveform. An object of the present invention is to provide an optimum excitation frequency setting method for determining a frequency and automatically setting the excitation frequency.

[0015]

A continuous jet type ink jet recording apparatus according to the present invention discharges pressurized ink from a nozzle as a continuous jet and makes the continuous jet uniform in synchronization with the excitation of a vibrator mounted on the nozzle. Forming means for splitting the ink particles into small-sized ink particles, charging means for selectively charging the ink particles, and deflecting the charged ink particles by a deflection electric field perpendicular to the jet flight axis in a direction perpendicular to the jet flight axis. In a continuous jet type ink jet recording apparatus comprising a deflecting unit and a separating unit that cuts deflected charged ink particles and passes straight uncharged ink particles, a variable frequency oscillation that outputs an excitation signal for exciting the vibrator is provided. Means, switch means for turning on / off the deflection electric field by the deflection means, and the deflection electric field is turned off by the switch means. In the state, a probe pulse generating unit that generates a probe pulse in synchronization with an excitation signal output from the variable frequency oscillation unit, a phase shift unit that shifts a phase between the excitation signal and the probe pulse, A conductive particle catcher that captures charged ink particles that have been charged by the probe pulse generated by the probe pulse generating means and that have passed through the separation means, and a charge value of the charged ink particles captured by the conductive particle catcher as a current value. Current detecting means for detecting, A / D converting means for converting the current value detected by the current detecting means into digital data, and setting the excitation frequency of the excitation signal to M (positive integer) for the variable frequency oscillating means. The phase shift means is instructed to sequentially switch to the stages, and the phase shift means is driven at the excitation frequency of each stage. Data in which the phase between the vibration signal and the probe pulse is shifted by 2π / N (N is a positive integer), and the digital data converted by the A / D conversion means at each stage is arranged in phase order. Is stored as jet current waveform data, and the minimum value of the jet current is obtained for the stored M sets of current waveform data.
And extract the phase corresponding to
While moving the phase in the direction in which the excitation signal is delayed,
The phase at which the cut current reaches a local maximum value is extracted,
The difference between the phase and the phase corresponding to the minimum value is smaller than the specified value.
If the excitation signal is further
Jet current is minimal while shifting the phase in the direction of delay
The phase that becomes the minimum value is extracted, and the phase that becomes the minimum value corresponds to the minimum value.
If the phase is equal , the maximum and minimum values of the jet current
Difference from value is stored as contrast at excitation frequency
The largest of the stored contrasts.
Search for last and optimize excitation frequency corresponding to it
And an optimal excitation frequency determining means for determining an excitation frequency and outputting an excitation signal of an optimal excitation frequency to the variable frequency oscillating means.

Further, in the continuous jet type ink jet recording apparatus of the present invention, the pressurized ink is ejected from the nozzle as a continuous jet, and the continuous jet having a uniform size is synchronized with the excitation of the vibrator mounted on the nozzle. N to split into ink particles
(An integer of 2 or more) jet forming means, n charging means for selectively charging ink particles, and ink particles charged by a deflection electric field orthogonal to the jet flight axis in a direction perpendicular to the jet flight axis. In a continuous jet type ink jet recording apparatus comprising a deflecting means for deflecting, and a separating means for cutting deflected charged ink particles and passing uncharged ink particles going straight, excitation for exciting the n vibrators in common Variable frequency oscillation means for outputting a signal,
Switch means for turning on / off the deflection electric field by the deflection means; and a probe pulse for generating a probe pulse in synchronization with an excitation signal output from the variable frequency oscillating means when the deflection electric field is turned off by the switch means. Generating means, n phase shift means for shifting the phase between the excitation signal and the probe pulse, and charged ink particles charged by the probe pulse generated by the probe pulse generating means and passing through the separating means , A current detecting means for detecting the charge of the charged ink particles captured by the conductive particle catcher as a current value, and converting the current value detected by the current detecting means into digital data. A / D converting means and the n number of jet forming means in this order. Instructing the frequency oscillating means to sequentially switch the excitation frequency of the excitation signal to M (positive integer) steps, and instructing the phase shift means corresponding to the excitation frequency of each step to correspond to the phase shift means by the excitation signal and the probe pulse. And the phase between them is shifted by 2π / N (N is a positive integer).
Data obtained by arranging digital data converted by the D conversion means in a phase order is stored as jet current waveform data,
For the accumulated n × M sets of current waveform data ,
Extract the phase corresponding to the minimum value of the
Move the phase in the direction that the excitation signal lags behind the pulse
While extracting the phase at which the jet current has a maximum value,
Defines the difference between the phase corresponding to the maximum value and the phase corresponding to the minimum value
If the value is smaller than the value,
While moving the phase in the direction in which the excitation signal is delayed,
Tsu theft current issues extract the phase to become a minimum value, the minimum value position
If the phase is equal to the phase corresponding to the minimum value, the jet current
The difference between the maximum value and the minimum value of
Accumulate as a strike and encourage from the accumulated contrast
Vibration frequency is common for each jet forming means
For each jet forming means
And the largest value among the minimum values of the obtained contrast
Optimal excitation frequency corresponding to minimum contrast
And an optimal excitation frequency determining means for determining an excitation frequency and outputting an excitation signal of an optimal excitation frequency to the variable frequency oscillating means.

Further, in the continuous jet type ink jet recording apparatus of the present invention, the pressurized ink is ejected from the nozzle as a continuous jet, and the continuous jet has a uniform size in synchronization with the excitation of the vibrator mounted on the nozzle. N to split into ink particles
(An integer of 2 or more) jet forming means; n charging means for selectively charging ink particles; and ink particles charged by a DC electric field orthogonal to the jet flight axis in a direction perpendicular to the jet flight axis. In a continuous jet type ink jet recording apparatus comprising a deflecting means for deflecting, and a separating means for cutting deflected charged ink particles and passing uncharged ink particles going straight, excitation for exciting the n vibrators in common Variable frequency oscillation means for outputting a signal,
Switch means for turning on / off the deflection electric field by the deflection means; and a probe pulse for generating a probe pulse in synchronization with an excitation signal output from the variable frequency oscillating means when the deflection electric field is turned off by the switch means. Generating means, n phase shift means for shifting the phase between the excitation signal and the probe pulse, and charged ink particles charged by the probe pulse generated by the probe pulse generating means and passing through the separating means Conductive particle catchers for capturing the current, n current detecting means for detecting the charged charges of the charged ink particles captured by the n conductive particle catchers as current values, respectively, N A / D conversion means for respectively converting the current value detected by the detection means into digital data; Instructing the variable frequency oscillating means to sequentially switch the excitation frequency of the excitation signal to M (positive integer) steps simultaneously for the n jet forming means, and corresponding phase shift means at each stage of the excitation frequency To shift the phase between the excitation signal and the probe pulse by 2π / N (N is a positive integer), and the A /
Data obtained by arranging digital data converted by the D conversion means in a phase order is stored as jet current waveform data,
For the accumulated n × M sets of current waveform data ,
Extract the phase corresponding to the minimum value of the
Move the phase in the direction that the excitation signal lags behind the pulse
While extracting the phase at which the jet current has a maximum value,
Defines the difference between the phase corresponding to the maximum value and the phase corresponding to the minimum value
If the value is smaller than the value,
Jefferies while moving the position phase in the direction in which the excitation signal is delayed
The phase at which the cut-off current reaches a local minimum value is extracted,
If the phase is equal to the phase corresponding to the minimum value, the jet current
The difference between the maximum value and the minimum value of
Accumulate as a strike and encourage from the accumulated contrast
Vibration frequency is common for each jet forming means
For each jet forming means
And the largest value among the minimum values of the obtained contrast
Optimal excitation frequency corresponding to minimum contrast
And an optimal excitation frequency determining means for determining an excitation frequency and outputting an excitation signal of an optimal excitation frequency to the variable frequency oscillating means.

[0018]

In the continuous jet ink jet recording apparatus of the present invention, the switch means turns off the deflection electric field by the deflection means,
The probe pulse generating means generates a probe pulse in synchronization with the excitation signal output from the variable frequency oscillating means while the deflection electric field is turned off by the switch means, and the phase shift means generates a phase between the excitation signal and the probe pulse. The conductive particle catcher captures the charged ink particles that have been charged by the probe pulse generated by the probe pulse generating means and passed through the separating means, and the current detection means has detected the charged ink particles captured by the conductive particle catcher. The A / D conversion means converts the current value detected by the current detection means into digital data, and the optimum excitation frequency determination means sets the excitation frequency of the excitation signal to the variable frequency oscillation means. M (positive integer) steps are sequentially instructed, and the phase shift means is controlled by the excitation frequency of each step. And the phase between the excitation signal and the probe pulse is shifted by 2π / N (N is a positive integer), and the data obtained by arranging the digital data converted by the A / D conversion means at each stage in the order of phase is Accumulated as jet current waveform data, and accumulated M sets of current waveform data
Extract the phase corresponding to the minimum value of the jet current for
And the excitation signal is delayed with respect to the probe pulse.
The phase at which the jet current reaches its maximum value while moving the phase
Extract the phase between the maximum value and the phase corresponding to the minimum value.
If the difference is smaller than the specified value,
And move the phase in the direction in which the excitation signal is delayed.
The phase at which the cut-off current reaches a local minimum value is extracted,
If the phase is equal to the phase corresponding to the minimum value, the jet current
The difference between the maximum value and the minimum value of
The contrast is stored as a
Search for a large contrast and the corresponding excitation
The frequency is determined as the optimum excitation frequency, and the variable frequency oscillator is instructed to output an excitation signal of the optimum excitation frequency.

Further, in the continuous jet type ink jet recording apparatus of the present invention, the switch means turns off the deflection electric field by the deflecting means, and the probe pulse generating means outputs from the variable frequency oscillating means with the deflection electric field turned off by the switch means. A probe pulse generated in synchronization with the excitation signal to be generated, n phase shifters shift the phase between the excitation signal and the probe pulse, and the conductive particle catcher generates a probe pulse generated by the probe pulse generator. The current detecting means detects the charged charge of the charged ink particles captured by the conductive particle catcher as a current value, and the A / D converting means detects the charged ink particles having passed through the separating means by the current detecting means. The detected current value is converted into digital data, and the optimum excitation frequency determining means is configured to have n jet type In order for the means, the variable frequency oscillating means is instructed to sequentially switch the excitation frequency of the excitation signal to M (positive integer) steps, and the excitation signal and the probe are supplied to the corresponding phase shift means at the excitation frequency of each step. The phase between the pulse and the pulse is instructed to be shifted by 2π / N (N is a positive integer), and the data obtained by arranging the digital data converted by the A / D converter in each stage in each stage in each jet forming means is arranged in order of phase accumulated as a jet current waveform data, the stored n × M sets of current waveform data
Extract the phase corresponding to the minimum value of the jet current
And the excitation signal is delayed with respect to the probe pulse.
The phase at which the jet current reaches its maximum value while moving the phase
Extract the phase between the maximum value and the phase corresponding to the minimum value.
If the difference is smaller than the specified value,
And move the phase in the direction in which the excitation signal is delayed.
The phase at which the cut-off current reaches a local minimum value is extracted,
If the phase is equal to the phase corresponding to the minimum value, the jet current
The difference between the maximum value and the minimum value of
Accumulate as a strike and encourage from the accumulated contrast
Vibration frequency is common for each jet forming means
For each jet forming means
And the largest value among the minimum values of the obtained contrast
Optimal excitation frequency corresponding to minimum contrast
And instructs the variable frequency oscillating means to output an excitation signal of the optimum excitation frequency.

Further, in the continuous jet type ink jet recording apparatus of the present invention, the switch means turns off the deflection electric field by the deflecting means, and the probe pulse generating means outputs from the variable frequency oscillating means with the deflection electric field turned off by the switch means. A probe pulse is generated in synchronization with the excitation signal generated, n phase shifters shift the phase between the excitation signal and the probe pulse, and n conductive particle catchers are generated by the probe pulse generator. Captures the charged ink particles that have been charged by the probe pulse and passed through the separating means, and the n current detection means detects the charged charges of the charged ink particles captured by the n conductive particle catchers as current values, respectively, The n A / D converters convert the current values detected by the n current detectors into digital data, respectively. And conversion, the optimal excitation frequency determining means n
At the same time, instructing the variable frequency oscillating means to sequentially switch the excitation frequency of the excitation signal to M (positive integer) steps for the plurality of jet forming means, and exciting the corresponding phase shift means at the excitation frequency of each step. The phase between the signal and the probe pulse is instructed to be shifted by 2π / N (N is a positive integer), and the digital data converted by the A / D conversion means at each stage is arranged in order for each jet forming means. The accumulated data is accumulated as jet current waveform data, and the accumulated n × M sets of current waveform data are
Extract the phase corresponding to the minimum value of the jet current, and
The phase is shifted in the direction that the excitation signal is delayed with respect to the pulse.
While extracting the phase at which the jet current has a maximum value,
The difference between the phase with the largest value and the phase with the smallest value is the specified value
Excitation signal for probe pulse
The jet current moves while shifting the phase in the direction
Extract the phase that has the minimum value and the phase that has the minimum value is the minimum value
Is equal to the phase corresponding to
Difference from local minimum value as contrast at excitation frequency
The excitation frequency is calculated from the accumulated contrast
The contrast common to each jet forming means
The minimum value of contrast is obtained for each jet forming means.
The largest contra from the minimum contrast values
The excitation frequency corresponding to the minimum value of the strike is determined as the optimal excitation frequency, and the variable frequency oscillator is instructed to output an excitation signal of the optimal excitation frequency.

[0021]

Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a configuration diagram showing a main part of a continuous jet type ink jet recording apparatus according to a first embodiment of the present invention. The continuous ejection type ink jet recording apparatus of the present embodiment
A nozzle 1 having an extremely thin circular orifice, an ink electrode 2 for setting the potential of the ink in the nozzle 1 to the ground level, a vibrator 3 composed of a piezoelectric vibrator mounted on the nozzle 1, and a circle concentric with the nozzle 1 A control electrode 4 having an opening or a slit-shaped opening and to which a charging control signal for controlling charging of the inkjet corresponding to image data is applied; a ground electrode 5 arranged behind the control electrode 4 and grounded; Ground electrode 5
To form a strong electric field perpendicular to the jet flight axis between the knife edge 6, the deflection power supply E1, and the grounding electrode 5 connected to the deflection power supply E1 to deflect the charged ink particles to the ground electrode 5 side. A deflection electrode 7 and a switch SW for switching between connecting the deflection electrode 7 to a deflection power source E1 and grounding
1, a reference oscillator CG for generating a reference clock CLK having an oscillation frequency designated by the MPU 10, and an excitation signal P obtained by dividing the reference clock CLK by 1 / N (positive integer).
And a pulse train θ in which the excitation signal PCLK is delayed in N stages according to the reference clock CLK.
₀ , θ ₁ , θ ₂ ,..., Θ _{N -1} and a delayed pulse train θ ₀ , θ ₁ , θ ₂ ,.
Multiplexer (2) MP for selecting any _one of θ _N-1
2, a vibrator driver VD for driving the vibrator 3 with a pulse selected by the multiplexer (2) MP2, a pulse width modulator PM for converting image data into a pulse width corresponding to a density gradation, and an excitation signal PCLK A probe pulse generator PG that generates a probe pulse whose pulse width is sufficiently shorter than the period of the excitation signal PCLK in synchronization with the rising or falling edge of the signal, and the rising or falling of the output of the pulse width modulator PM A synchronization circuit SC for synchronizing an edge with a rising or falling edge of the excitation signal PCLK;
A multiplexer (1) MP1 for selecting one of a probe pulse from the probe pulse generator PG and an output from the synchronization circuit SC; and a control electrode 4 which amplifies the voltage of the output of the multiplexer (1) MP1 and charges it as a charge control signal. , A conductive particle catcher 8 serving also as a detection electrode disposed in a region (hereinafter, referred to as a home position) behind the ground electrode 5 and the deflection electrode 7 which is not related to recording, and a conductive particle catcher 8. , A current detector (current / voltage converter) CD for measuring the charge of the ink particles discharged to the conductive particle catcher 8 by the ink jet, and the output of the current detector CD as A. A / D converter ADC for / D (analog / digital) conversion, and reference clock based on output of A / D converter ADC From MPU10 Metropolitan specifying the reference oscillator CG to oscillate at the oscillation frequency of LK, a main part is configured. The MPU 10 also controls the entire system of the continuous ejection type ink jet recording apparatus of the present embodiment.

The reference oscillator CG adjusts the oscillation frequency of the reference clock CLK from the center frequency by a command from the MPU 10.
The frequencies f ₀ , f ₁ , f ₂ , f ₃ ,..., F _M-1 which divide the frequency band of 5% to ± 10% into M (positive integers) are set.

The delay pulse generator DG includes, for example, Ser
It is composed of an ial-In Parallel-Out type N-bit shift register.

The probe pulse generator PG is composed of, for example, a monostable multivibrator triggered by an edge of the excitation signal PCLK.

The current detector CD is composed of an integrating circuit. For example, the integration time is 2 × 10 ⁴ times or more of the particle formation period, that is, the charge of 2 × 10 ⁴ or more ink particles is integrated and detected.
No. 1444753).

Next, the operation of the thus-configured continuous jet type ink jet recording apparatus according to the first embodiment will be described. This operation is executed when a carriage (not shown) on which the nozzle 1 is mounted is at the home position and a process for automatically setting a previously prepared optimal excitation frequency is started.

First, ink is supplied to an ink pump (not shown).
, And is guided to the nozzle 1 through an ink tube (not shown), and the inkjet is ejected from the nozzle 1 to be kept in a steady state. Further, the MPU 10 switches the switch SW1 to the ground side to set the deflection electrode 7 to the ground level. As a result, the deflection electric field between the ground electrode 5 and the deflection electrode 7 is turned off, and the charged ink particles are also removed from the knife edge 6.
Pass through. Further, the MPU 10 causes the multiplexer (1) MP1 to select the output of the probe pulse generator PG.

In this state, the MPU 10 sequentially instructs the following operations, sets the oscillation frequency of the reference clock CLK of the reference oscillator CG, and optimizes the excitation frequency of the excitation signal PCLK.

The oscillation frequency of the reference clock CLK is f
_It is set to _{0, and} the jet current waveform (charge characteristics of the jet) at f ₀ is measured by the following procedure.

The reference oscillator CG outputs a reference clock CLK, and the reference clock CLK has a frequency of 1 by a frequency divider FD.
/ N, and input to the delay pulse generator DG, the probe pulse generator PG, and the synchronization circuit SC as the excitation signal PCLK. That is, the excitation frequency PCLK of the excitation signal PCLK (hereinafter, the signal and the frequency of the signal are denoted by the same reference numerals) is CLK / N (for example, CLK = 16 MHz, N = 16, PCLK = 1MH).
z).

The delay pulse generator DG receives the excitation signal PCL
K is data, the reference clock CLK is input as a shift clock, and N sets of pulse trains θ ₀ , θ ₁ , θ ₂ ,..., One cycle of the excitation signal PCLK are sequentially delayed by 2π / N.
Output θ _N-1 . N sets of pulse trains θ ₀ , θ ₁ , θ ₂ ,
, .Theta.N _-1 are selected by the MPU 10 via the multiplexer (2) MP2 and output to the transducer driver VD. The vibrator driver VD outputs the vibrator 3 according to the output from the multiplexer (2) MP2.
To excite. Thus, the ink jet ejected from the nozzle 1 is turned into particles in synchronization with the excitation by the vibrator 3.

The probe pulse generator PG outputs the excitation signal P
In synchronization with the rising or falling edge of CLK (same as during recording), a probe pulse having a pulse width sufficiently shorter than the period of the excitation signal PCLK is generated as shown in FIG. , Period of excitation signal PCLK = 1 μm
0.1 to 0.3 μsec at 1 sec (1 MHz oscillation)
c).

The probe pulse output from the probe pulse generator PG is input to the high-voltage switch HVS via the multiplexer (1) MP1, and is output to the high-voltage switch HVS.
And is applied to the control electrode 4 as a charge control signal. Therefore, the ink particles that are converted into particles in synchronization with the excitation of the vibrator 3 are charged according to the probe pulse. Now, as illustrated in FIG. 2, since the polarity of the probe pulse is negative, the ink particles are always charged and the time (for example, 0. 0) when the probe pulse is applied to the control electrode 4 as a control signal. The charging voltage is turned off for 1 to 0.3 μsec).

Since the deflection electric field is turned off, the ink particles charged by the control electrode 4 pass through the knife edge 6 without being deflected, and are insulated from the others at the home position. Captured by

The charge of the conductive particles catcher 8 captured charged ink particles appears as a voltage by the current detector CD via the shielded wires 9 as a jet current I _j. The jet current I _j converted into the voltage is supplied to the A / D converter AD
The data is converted into digital data by C and output to the data bus of the MPU 10.

[0037] Measurement of the jet current I _j, as shown in FIG. 2, MPU 10 is sequentially switched multiplexer (2) MP2, 2πi / N (i relative to the excitation signal PCLK
= 0,1,2, ..., N-1 ) pulses theta ₀ phase-shifted, theta _1, theta _2, ..., in theta _N-1 by driving the vibrator 3 sequentially exciting the nozzle 1, Performed for each phase.

The value of the jet current I _j measured for each phase is A / D converted by an A / D converter ADC,
It is stored in a memory (not shown) of the MPU 10.

FIG. 3 is a diagram showing an example of a jet current waveform in which the values of the jet current I _j measured for each phase using the probe pulse are plotted. The presence or absence of the half-charged ink particles is determined by observing with a microscope with a strobe light. Figure 3 shows the measurement results.
It is Johan Nilsso
n, “Applications of Micro
Drops ", Dept. of Electrical
Measurements, Lund Inst. o
f Tecology, Report 6/1993
Pp. 90-101. As for the measurement technique of the jet current I _j, it is disclosed in detail in JP-A-4-144753 by the present inventor.

Hereinafter, similarly, the MPU 10 sets the oscillation frequency of the reference clock CLK of the reference oscillator CG to f ₁ , f ₂ , f ₃ ,..., F _{M -1} .
The jet current waveform in each is measured.

Each oscillation frequency f ₀ , f ₁ , f ₂ ,
When the measurement of the M sets of jet current waveform data at f ₃ ,..., f _M−1 is completed, the MPU 10 extracts the characteristics of each jet current waveform based on the M sets of jet current waveform data stored in the memory. The optimum excitation frequency of the excitation signal PCLK is determined, and the reference clock CLK of the reference oscillator CG is determined.
Set the oscillation frequency of More specifically, since the satellite particle problem and the fuzzy jet problem can be determined empirically from the shape of the jet current waveform, the MPU 10 first determines whether satellite particles are generated from the M sets of jet current waveform data. , An excitation frequency that quickly merges in the control electrode 4 even if it occurs and does not adversely affect the main particles is extracted, and then the particleization phase is the most stable (the least fuzzy) among the extracted excitation frequencies. ) Determine the excitation frequency and use it as the optimal excitation frequency.

FIG. 4 shows a normal jet current waveform (A) in which the satellite particle problem does not occur, and jet current waveforms (B) and (C) in which the satellite particle problem occurs. The normal jet current waveform (A) is 1
This is a simple waveform having one maximum point (maximum point) and one minimum point (minimum point). Also, θ _N-1 → θ _N-2 →… → θ
_{When the} phase is delayed from _{1 to} θ ₀ , a local maximum point appears relatively near the local minimum point (the phase difference is small). In the normal jet current waveform (A), the maximum point corresponds to the particleization phase of the main particle. On the other hand, the problematic jet current waveform (B) is a waveform having two local maximum points and two local minimum points. When the phase is delayed from θ _N-1 → θ _N-2 →… → θ ₁ → θ ₀ , the local maximum point that appears next to the minimum point is the particleized phase point of the main particle, and further passes through the local minimum point And
The maximum point appears behind it. In addition, the problematic jet current waveform (C) is a waveform in which there is one maximum point (maximum point) and one minimum point (minimum point), and both are extremely separated (the phase difference is large). . θ _N-1 → θ _N-2 →… →
When the phase is delayed by θ ₁ → θ ₀ , a local maximum point appears at a position behind the local minimum point (a large phase difference). This maximum point does not correspond to the graining phase of the main particles. It can be said that the problematic jet current waveform (C) is a case where a small minimum point does not occur in the problematic jet current waveform (B). To extract only the normal jet current waveform (A) from the three types of jet current waveforms (A), (B) and (C), for example, first find the minimum point and delay the phase from that point. When I went,
If a maximum point is found within a certain phase, it can be determined that the waveform is a normal jet current waveform (A), and that the others are problematic jet current waveforms (B) or (C). The value of the constant phase can be determined empirically.

FIG. 5 is a diagram showing a jet current waveform (A) in which the particle phase is stable and a jet current waveform (D) in which the particle phase is unstable (fuzzy jet). Since the current detector CD is constituted by an integrating circuit, an unstable jet current waveform granulation phase (D) is a particle of phase compared to the stable jet current waveform (A), a jet current I _j Contrast ΔI _j which is the difference between the maximum value and the minimum value
Becomes smaller (ΔI _j (D) <ΔI _j (A)).

From the above, first, the jet current waveform having the satellite particle problem is removed from the M sets of jet current waveforms, and then the jet current waveform which maximizes the contrast ΔI _j from the remaining jet current waveforms Is determined, the excitation frequency becomes the optimal excitation frequency (criterion for determining the optimal excitation frequency).

FIG. 6 is a flowchart showing the optimum excitation frequency determination processing executed by the MPU 10 based on the above-mentioned criteria for determining the optimum excitation frequency. Referring to FIG. 6, the optimal excitation frequency determination process includes a current waveform data extraction step S101, a jet current minimum value corresponding phase extraction step S102, a jet current maximum value corresponding phase extraction step S103, a phase difference determination step S104, Jet current minimum value corresponding phase extraction step S105, minimum value corresponding phase / minimum value corresponding phase comparison step S106, contrast storage step S107, excitation frequency maximum determination step S108, excitation frequency increment step S109, and optimal excitation frequency determination It consists of step S110.

Here, the operation of the optimum excitation frequency determination processing in the MPU 10 will be described with reference to FIG.

First, the MPU 10 sets the excitation frequency f _K (k
= 0) (step S101), and the minimum value I _j (mi of the jet current I _j )
Extract the phase θ _min corresponding to n) (Step S10)
2).

Next, the MPU 10 extracts the phase θ _{max at} which the jet current I _j has a maximum value while moving the phase in the direction (θ _{N -1} → θ ₀ ) in which the excitation signal PCLK is delayed with respect to the probe pulse. (Step S103).

Subsequently, the MPU 10 sets (θ _max −
θ _min ) is determined whether it is smaller than an empirically determined specified value Δθ _S (step S104), and if not, the excitation frequency f _K is incremented (step S1).
09), control is returned to step S101.

If (θ _max −θ _min ) is smaller than the specified value Δθ _S , the MPU 10 controls the jet current while moving the phase in the direction (θ _N−1 → θ ₀ ) in which the excitation signal PCLK is delayed with respect to the probe pulse. I _j is the minimum value I _j ′ (mi
The phase θ ′ _min that becomes n) is extracted (Step S10)
5).

Next, the MPU 10 determines whether or not θ ′ _min is equal to θ _min (step S106). If not equal, the MPU 10 increments the excitation frequency f _K (step S109) and returns control to step S101.

If θ ′ _min is equal to θ _min , MPU1
0 stores ΔI _j = I _j (max) −I _j (min) as contrast at the excitation frequency f _K in the memory (step S107).

[0053] Subsequently, MPU 10 is the excitation frequency f _K is determined whether or equal to the maximum excitation frequency f _M-1 (step S108), increments the excitation frequency f _K if cry equal (step S109), step S101
Return control to

If the excitation frequency f _K is equal to the maximum excitation frequency f _M−1 , the MPU 10 retrieves the maximum value ΔI _j (max) from the contrast ΔI _j stored in the memory, and finds the corresponding excitation frequency. the f _K the optimum excitation frequency f _opt (step S110), and ends the process.

After determining the optimum excitation frequency f _opt , the MPU 10 instructs the reference oscillator CG to oscillate at the corresponding oscillation frequency N · f _opt .

After that, the MPU 10 switches the switch S
When W1 is switched to the deflection power supply E1 side, the multiplexer (1) MP1 is switched to select the output of the synchronization circuit SC, and the multiplexer (2) MP2 is switched to select an appropriate excitation phase. The recording device enters the print mode.

FIG. 7 is a block diagram showing a main part of a continuous jet type ink jet recording apparatus according to a second embodiment of the present invention. The continuous ejection type ink jet recording apparatus of the present embodiment
In the continuous ejection type ink jet recording apparatus of the first embodiment shown in FIG. 1, when the phase between the particleization phase of the ink jet and the charge control signal is designated, the excitation signal PCLK is delayed to designate the phase. On the other hand, the phase is designated by delaying the charge control signal. That is, in the continuous ejection type ink jet recording apparatus of this embodiment, the excitation signal PCLK is directly input to the vibrator driver VD, while the output of the multiplexer (2) MP2 is input to the probe pulse generator PG and the synchronization circuit SC. Signal is input. Therefore, all the parts correspond to the parts in the continuous jet type ink jet recording apparatus of the first embodiment shown in FIG. 1, and the corresponding parts are denoted by the same reference numerals and their detailed description is omitted.

[0058] In a continuous jet type ink jet recording apparatus of the second embodiment constructed in this manner, only in that the measurement of the jet current I _j by shifting the phase of the probe pulse by 2 [pi / N is different, Fig. 1 as in the continuous jet type ink jet recording apparatus of the first embodiment shown, each excitation frequency _{f 0, f 1, f 2} , f 3, ..., f M-1
Then, jet current waveform data is collected. However, in this case, since the phase shift between the excitation signal PCLK and the charging control signal is reversed, the jet current waveform is symmetric (mirror image) with respect to the left-right direction as shown in FIGS. The process of extracting the characteristics of the jet current waveform to determine the optimum excitation frequency can be easily inferred from the continuous ejection type ink jet recording apparatus of the first embodiment, and thus the detailed description is omitted.

FIG. 8 is a block diagram showing a main part of a continuous jet type ink jet recording apparatus according to a third embodiment of the present invention. The continuous ejection type ink jet recording apparatus of the present embodiment
This is a continuous ejection type ink jet recording apparatus capable of color printing equipped with a plurality of nozzles 1. The reference oscillator CG, frequency divider FD, and ground electrode 5 in the continuous ejection type ink jet recording apparatus of the first embodiment shown in FIG. , Knife edge 6, deflection electrode 7, deflection power supply E1, switch SW1, delay pulse generator DG, probe pulse generator PG, conductive particle catcher 8, shield wire 9, current detector CD,
Except for the A / D converter ADC and the MPU 10, the four independent colors of C (cyan), M (magenta), Y (yellow), and BK (black) are configured. Therefore, parts corresponding to parts in the continuous ejection type ink jet recording apparatus of the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. If the reference oscillator CG and the frequency divider FD are also made independent of four colors, the number of ink particles generated per unit time for each color will be different, and the amount of ink attached to the four colors on the recording medium will be controlled. In the case of a continuous ejection type ink jet recording apparatus capable of performing color printing by expressing colors, a disadvantage occurs.

In the continuous jet type ink jet recording apparatus of the third embodiment thus constituted, the excitation frequencies f ₀ , f ₁ , f ₂ , f ₃ ,...
After measuring the jet current waveform data (data number: 4M) at f _{M- 1} , first, if any of the four nozzles 1 has a jet current waveform having a satellite particle problem, its excitation frequency is Also excluded from the other three nozzles 1,
Next, in the remaining jet current waveform, the excitation frequency at which the minimum value ΔI _j (min) becomes the maximum among the four contrasts ΔI _j corresponding to the four nozzles 1 is set as the optimal excitation frequency (optimum excitation). Frequency criterion).

FIG. 9 is a flowchart showing the optimum excitation frequency determination processing executed by the MPU 10 based on the above-mentioned criteria for determining the optimum excitation frequency. Referring to FIG. 9, the optimal excitation frequency determination processing is performed in the nozzle number 1 setting step S2.
00, a current waveform data extraction step S201, a jet current minimum value corresponding phase extraction step S202, a jet current maximum value corresponding phase extraction step S203, a phase difference determination step S204, and a jet current minimum value corresponding phase extraction step S205. , Minimum value corresponding phase / minimum value corresponding phase comparison step S206, contrast storage step S207, excitation frequency maximum determination step S20
8, an excitation frequency increment step S209,
Nozzle number 4 determination step S210, nozzle number increment step S211, minimum contrast value extraction step S212, and optimal excitation frequency determination step S
213.

Here, the operation of the optimum excitation frequency determination processing in the MPU 10 will be described with reference to FIG.

First, the MPU 10 sets the nozzle number n to 1 (step S200), and sets the excitation frequency f _K (k = 0)
) (Step S201), and the minimum value I _j (min) of the jet current I _j
Is extracted (step S20).
2).

Next, the MPU 10 extracts the phase θ _{max at} which the jet current I _j reaches a local maximum value while moving the phase in a direction (θ _{N -1} → θ ₀ ) in which the excitation signal PCLK is delayed with respect to the probe pulse. (Step S203).

Subsequently, the MPU 10 calculates (θ _max −
θ _min ) is determined whether it is smaller than an empirically determined specified value Δθ _S (step S204). If not smaller, the excitation frequency f _K is incremented (step S2).
09), control is returned to step S201.

If (θ _max −θ _min ) is smaller than the specified value Δθ _S , the MPU 10 controls the jet current while shifting the phase in the direction (θ _N−1 → θ ₀ ) in which the excitation signal PCLK is delayed with respect to the probe pulse. I _j is the minimum value I _j ′ (mi
The phase θ ′ _min that becomes n) is extracted (Step S20)
5).

Next, the MPU 10 determines whether or not θ ′ _min is equal to θ _min (step S206). If not equal, the MPU 10 increments the excitation frequency f _K (step S209) and returns control to step S201.

If θ ′ _min is equal to θ _min , MPU1
0 stores ΔI _j = I _j (max) −I _j (min) in the memory as the contrast at the excitation frequency f _K (step S207).

[0069] Subsequently, MPU 10 is the excitation frequency f _K is determined whether or equal to the maximum excitation frequency f _M-1 (step S208), increments the excitation frequency f _K if cry equal (step S209), step S201
Return control to

If the excitation frequency f _K is equal to the maximum excitation frequency f _M−1 , the MPU 10 determines whether or not the nozzle number n is 4 (Step S210). The value is incremented by one (step S211), control is returned to step S201, and steps S201 to S208 are repeated by the number of nozzles 1.

[0071] In step S210, the nozzle number n is 4, MPU 10 is excited from the accumulated contrast [Delta] I _j in the memory frequency f _K is the contrast for common contrast [Delta] I _j in each nozzle 1 in the nozzle 1 extract the [Delta] I _j minimum [Delta] I _j of (min) and stored in the memory (step S212), the minimum value [Delta] I _j of the largest contrast [Delta] I _j from the minimum value [Delta] I _j of the stored contrast [Delta] I _j (min) The excitation frequency f _K corresponding to (min) is set as the optimal excitation frequency f _opt (step S213), and the process ends.

By the way, in the continuous jet type ink jet recording apparatus of the third embodiment shown in FIG.
In contrast, since the conductive particle catcher 8, the shield wire 9, the current detector CD, and the A / D converter ADC are provided one by one, the jet current waveform from each nozzle 1 is measured in time series. However, the conductive particle catcher 8, the shield wire 9, the current detector CD and the A /
If a D converter ADC is provided for each nozzle 1, parallel measurement of the jet current waveform becomes possible, and the measurement time is greatly reduced.

Further, as in the continuous jet type ink jet recording apparatus of the second embodiment shown in FIG.
The configuration in which the charge control signal is delayed for
It is obvious that the present invention can be similarly applied to the continuous jet type ink jet recording apparatus of the third embodiment using a plurality of nozzles 1.

[0074]

As described above, according to the continuous jet type ink jet recording apparatus of the present invention, variable frequency oscillating means, switch means, probe pulse generating means, phase shift means, conductive particle catcher, current detecting means, A / D
A conversion means and an optimum excitation frequency determination means are provided, the jet current is measured while shifting the phase at the M-stage excitation frequency, and M sets of jet current waveform data in which the jet currents are arranged in phase order are accumulated. By extracting the characteristics of each jet current waveform based on the jet current waveform data and automatically determining and setting the optimal excitation frequency, the complexity of actually printing a test image can be avoided, Since the criterion for determining the optimal excitation frequency is based on the detected value of the jet current, it is possible to make extremely accurate determinations, and since the determination and setting of the optimal excitation frequency is automated, extremely simple and high-speed operation becomes possible. This has the effect.

According to the continuous jet type ink jet recording apparatus of the present invention, the variable frequency oscillating means, the switching means, the probe pulse generating means, the n phase shift means,
A conductive particle catcher, a current detection means, an A / D conversion means, and an optimum excitation frequency determination means are provided, and the jet current is measured for the n number of jet formation means while sequentially shifting the phase at an M-stage excitation frequency; The optimal excitation frequency is automatically determined by accumulating n × M sets of jet current waveform data in which the jet currents are arranged in phase order and extracting the characteristics of each jet current waveform based on the n × M sets of jet current waveform data. The ability to determine and set the value avoids the complexity of actually printing a test image, and enables highly accurate judgment because the criterion for determining the optimal excitation frequency is based on the detected value of the jet current It is said that extremely simple and high-speed operation becomes possible because the determination and setting of the optimal excitation frequency are automated. Has the effect.

Further, according to the continuous jet type ink jet recording apparatus of the present invention, variable frequency oscillating means, switch means, probe pulse generating means, n phase shift means,
n conductive particle catchers, n current detecting means, n
A / D conversion means and optimum excitation frequency determination means are provided, and at the same time, the jet current is measured for the n jet formation means while shifting the phase at the M-stage excitation frequency, and the jet currents are arranged in phase order. × M sets of jet current waveform data are accumulated, and the characteristic of each jet current waveform is extracted based on the n × M sets of jet current waveform data, so that the optimum excitation frequency can be automatically determined and set. As a result, it is possible to avoid the complexity of actually printing a test image, and because the criterion for determining the optimal excitation frequency is based on the detected value of the jet current, it is possible to make an extremely accurate determination and further determine the optimal excitation frequency. In addition, since the setting is automated, there is an effect that extremely simple and high-speed operation becomes possible.

Further, according to the optimum excitation frequency setting method of the present invention, the excitation frequency is switched to M stages to measure M sets of jet current waveform data, and each jet current is measured based on the M sets of jet current waveform data. By automatically determining and setting the optimal excitation frequency by extracting the characteristics of the waveform, the criterion for determining the optimal excitation frequency is based on the detected value of the jet current, enabling extremely accurate determination. It has the effect of becoming.

According to the optimum excitation frequency setting method of the present invention, the excitation frequency is set to M for the n nozzles in order.
Switch to the stage, measure nxM sets of jet current waveform data, extract the characteristics of each jet current waveform based on nxM sets of jet current waveform data, automatically determine and set the optimal excitation frequency With this configuration, since the criterion for determining the optimum excitation frequency is based on the detected value of the jet current, there is an effect that extremely accurate determination can be performed.

Further, according to the optimum excitation frequency setting method of the present invention, the excitation frequency is simultaneously switched to M stages for n nozzles, and n × M sets of jet current waveform data are measured. By extracting the characteristics of each jet current waveform based on the jet current waveform data and automatically determining and setting the optimum excitation frequency, the criterion for the optimum excitation frequency is based on the detected value of the jet current. Therefore, there is an effect that extremely accurate judgment can be made.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a main part of a continuous ejection type ink jet recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a timing chart showing respective outputs of a frequency divider, a probe pulse generator, and a delay pulse generator in FIG.

FIG. 3 is a diagram exemplifying a jet current waveform obtained by plotting a value of a jet current measured in the continuous jet ink jet recording apparatus of the first embodiment.

FIG. 4 is a diagram exemplifying a normal jet current waveform and a jet current waveform having a satellite particle problem measured in the continuous jet ink jet recording apparatus of the first embodiment.

FIG. 5 is a diagram exemplifying a stable jet current waveform and a jet current waveform having a fuzzy jet problem measured in the continuous jet ink jet recording apparatus of the first embodiment.

FIG. 6 is a flowchart showing an optimum excitation frequency determination process executed by the MPU in FIG. 1;

FIG. 7 is a configuration diagram showing a main part of a continuous ejection type ink jet recording apparatus according to a second embodiment of the present invention.

FIG. 8 is a configuration diagram showing a main part of a continuous jet ink jet recording apparatus according to a third embodiment of the present invention.

FIG. 9 is a flowchart showing an optimum excitation frequency determination process executed by the MPU in FIG. 8;

FIG. 10 is a configuration diagram showing a main part of a conventional continuous jet type ink jet recording apparatus.

[Explanation of symbols]

1 Nozzle 2 Ink electrode 3 Vibrator 4 Control electrode 5 Ground electrode 6 Knife edge 7 Deflection electrode 8 Conductive particle catcher 9 Shield wire 10 MPU ADC A / D converter CD Current detector CG Reference oscillator CLK Reference clock DG Delay pulse generation DCLK Pixel recording command signal E1 Deflection power supply FD divider HVS High voltage switch MP1 Multiplexer (1) MP2 Multiplexer (2) PCLK Excitation signal PG Probe pulse generator PM Pulse width modulator SC Synchronization circuit SW1 Switch VD Oscillator driver S101 , S201 Current waveform data extraction step S102, S202 Jet current minimum value corresponding phase extraction step S103, S203 Jet current maximum value corresponding phase extraction step S104, S204 Phase difference determination step S105, 205 Jet current minimum value corresponding phase extraction step S106, S206 Minimum value corresponding phase / minimum value corresponding phase comparison step S107, S207 Contrast storage step S108, S208 Excitation frequency maximum determination step S109, S209 Excitation frequency increment step S110, S213 Optimum excitation frequency Determination step S200 Nozzle number 1 setting step S210 Nozzle number 4 determination step S211 Nozzle number increment step S212 Contrast minimum value extraction step

Claims (9)

(57) [Claims] 1. A jet forming means for discharging pressurized ink from a nozzle as a continuous jet and dividing the continuous jet into ink particles of a uniform size in synchronization with the excitation of a vibrator mounted on the nozzle, and ink. Charging means for selectively charging the particles, deflecting means for deflecting the ink particles charged by a deflection electric field orthogonal to the jet flight axis in a direction perpendicular to the jet flight axis, and cutting the deflected charged ink particles to go straight A continuous jet type ink jet recording apparatus comprising: a separation unit that allows uncharged ink particles to pass through; a variable frequency oscillation unit that outputs an excitation signal for exciting the vibrator; With the deflection electric field turned off by the switch means,
Probe pulse generation means for generating a probe pulse in synchronization with an excitation signal output from the variable frequency oscillation means; phase shift means for shifting the phase between the excitation signal and the probe pulse; A conductive particle catcher that captures charged ink particles that have been charged by the probe pulse generated by the means and passed through the separation unit; and a current that detects, as a current value, the charge of the charged ink particles captured by the conductive particle catcher. Detecting means; A / D converting means for converting a current value detected by the current detecting means into digital data; and an exciting frequency of the exciting signal for the variable frequency oscillating means in M (positive integer) stages. Switching to the phase shift means at the excitation frequency of each stage. 2π phase between said probe pulse
/ N (N is a positive integer), and digital data converted by the A / D conversion means in each stage are arranged in the order of phase and accumulated as jet current waveform data. for the set of the current waveform data
Extract the phase corresponding to the minimum value of the jet current
The excitation signal is delayed with respect to the probe pulse.
The phase at which the jet current reaches its maximum value while moving the phase
Extracting a phase corresponding to the phase and the minimum value becomes maximum value
If the difference is smaller than the specified value,
Phase in the direction in which the excitation signal is delayed with respect to
While extracting the phase at which the jet current has a minimum value,
If the phase of the value is equal to the phase corresponding to the minimum value,
The difference between the maximum value and the minimum value of the jet current is set at the excitation frequency.
Accumulated as contrast, and the accumulated contrast
Search for the largest contrast among
Determining the excitation frequency of response and optimum excitation frequency, continuous jet type ink jet, characterized by having the optimum excitation frequency determining means for instructing to output the excitation signal of the optimum excitation frequency for the variable frequency oscillating means Recording device. 2. A pressurized ink is ejected from a nozzle as a continuous jet, and the continuous jet is divided into ink particles of a uniform size in synchronization with the excitation of a vibrator mounted on the nozzle.
(An integer of 2 or more) jet forming means, n charging means for selectively charging ink particles, and ink particles charged by a deflection electric field orthogonal to the jet flight axis in a direction perpendicular to the jet flight axis. In a continuous jet type ink jet recording apparatus, comprising: a deflecting unit for deflecting, and a separating unit for cutting the deflected charged ink particles and passing the uncharged ink particles going straight, an excitation for exciting the n vibrators in common A variable frequency oscillating means for outputting a signal, a switch means for turning on / off a deflection electric field by the deflecting means, and a state in which the deflection electric field is turned off by the switch means,
A probe pulse generation unit that generates a probe pulse in synchronization with an excitation signal output from the variable frequency oscillation unit; n phase shift units that shift a phase between the excitation signal and the probe pulse; A conductive particle catcher that is charged by the probe pulse generated by the probe pulse generating means and captures charged ink particles that have passed through the separating means; and a charge value of the charged ink particles captured by the conductive particle catcher as a current value. Current detecting means for detecting, A / D converting means for converting a current value detected by the current detecting means into digital data, and the n jet forming means in order with respect to the variable frequency oscillating means. Set the excitation frequency of the excitation signal to M
(Positive integer) in order to sequentially switch the phases, and the phase between the excitation signal and the probe pulse is set to 2π / N for the corresponding phase shift means at the excitation frequency of each step.
(N is a positive integer), and the digital data converted by the A / D conversion means in each stage is arranged in the phase order for each jet forming means, and the data is stored as jet current waveform data. N × M
For the set of current waveform data ,
Extract the corresponding phase and precede the probe pulse
While moving the phase in the direction in which the excitation signal is delayed,
The phase at which the current reaches its maximum value is extracted, and the phase at which the maximum value
Is smaller than the specified value.
If the excitation signal is further
Jet current is minimal while shifting the phase in the direction of delay
The phase that becomes the minimum value is extracted, and the phase that becomes the minimum value corresponds to the minimum value.
If the phase is equal, the maximum and minimum values of the jet current
Difference from value is stored as contrast at excitation frequency
The excitation frequency is selected from the stored contrast
Each contrast for the contrast common to the jet forming means
The minimum value of the contrast was obtained for each
Highest contrast among minimum contrast values
And determining an excitation frequency corresponding to the minimum value as an optimal excitation frequency, and instructing the variable frequency oscillating means to output an excitation signal of the optimal excitation frequency. Continuous ejection type ink jet recording device. 3. A pressurized ink is ejected from a nozzle as a continuous jet, and the continuous jet is divided into ink particles of a uniform size in synchronization with the excitation of a vibrator mounted on the nozzle.
(An integer of 2 or more) jet forming means, n charging means for selectively charging ink particles, and ink particles charged by a deflection electric field orthogonal to the jet flight axis in a direction perpendicular to the jet flight axis. In a continuous jet type ink jet recording apparatus, comprising: a deflecting unit for deflecting, and a separating unit for cutting the deflected charged ink particles and passing the uncharged ink particles going straight, an excitation for exciting the n vibrators in common A variable frequency oscillating means for outputting a signal, a switch means for turning on / off a deflection electric field by the deflecting means, and a state in which the deflection electric field is turned off by the switch means,
A probe pulse generation unit that generates a probe pulse in synchronization with an excitation signal output from the variable frequency oscillation unit; n phase shift units that shift a phase between the excitation signal and the probe pulse; N conductive particle catchers that are charged by the probe pulse generated by the probe pulse generating means and capture the charged ink particles that have passed through the separating means; and n of the charged ink particles captured by the n conductive particle catchers. N pieces of current detecting means for respectively detecting the charged electric charge as a current value; n pieces of A / D converting means for respectively converting the current values detected by these n pieces of current detecting means into digital data; At the same time, the excitation frequency of the excitation signal is set to M for the variable frequency oscillation means.
(Positive integer) in order to sequentially switch the phases, and the phase between the excitation signal and the probe pulse is set to 2π / N for the corresponding phase shift means at the excitation frequency of each step.
(N is a positive integer), and the digital data converted by the A / D conversion means in each stage is arranged in the phase order for each jet forming means, and the data is stored as jet current waveform data. N × M
For the set of current waveform data ,
Extract the corresponding phase and precede the probe pulse
While moving the phase in the direction in which the excitation signal is delayed,
The phase at which the current reaches its maximum value is extracted, and the phase at which the maximum value
Is smaller than the specified value.
If the excitation signal is further
Jet current is minimal while shifting the phase in the direction of delay
The phase that becomes the minimum value is extracted, and the phase that becomes the minimum value corresponds to the minimum value.
If the phase is equal, the maximum and minimum values of the jet current
Difference from value is stored as contrast at excitation frequency
The excitation frequency is selected from the stored contrast
Each contrast for the contrast common to the jet forming means
The minimum value of the contrast was obtained for each
Highest contrast among minimum contrast values
And determining an excitation frequency corresponding to the minimum value as an optimal excitation frequency, and instructing the variable frequency oscillating means to output an excitation signal of the optimal excitation frequency. Continuous ejection type ink jet recording device. Wherein said phase shifting means, to fix the phase of the probe pulse, continuous jet type ink jet recording apparatus of claim 1 for shifting the phase of the excitation signal, 2 or 3 wherein. Wherein said phase shifting means, to fix the phase of the excitation signal, a continuous jet type ink jet recording apparatus of phase-shifted to claim 1, 2 or 3 wherein the said probe pulse. Wherein said current detecting means, a continuous jet type ink jet recording apparatus according to claim 1, 2 or 3, further comprising an integrator. 7. A jet forming step of discharging the pressurized ink from the nozzle as a continuous jet and dividing the continuous jet into ink particles of a uniform size in synchronization with the excitation of the vibrator mounted on the nozzle; A probe pulse generating step of generating a probe pulse in synchronization with an excitation signal of the vibrator; a charging step of charging the ink particles by a probe pulse generated in the probe pulse generating step; and a charging step of charging in the charging step. A current detection step of detecting the charge of the ink particles as a current value; an A / D conversion step of converting the current value detected in the current detection step into digital data; and setting the excitation frequency of the excitation signal to M (a positive integer) ), The phase between the excitation signal and the probe pulse is shifted by 2π / N (N is a positive integer) at the excitation frequency of each step. The data arranged in phase order digital data to which the converted by the A / D conversion process in each step is stored as a jet current waveform data, the accumulated M sets of the current waveform data, corresponding to the minimum value of the jet current Extract phase
And the excitation signal is delayed with respect to the probe pulse.
The jet current to a maximum value while shifting the phase in
Phase corresponding to the maximum value and the minimum value.
That if the difference between the position phase is smaller than the specified value, further the pro
Phase in the direction in which the excitation signal lags behind the
Extract the phase at which the jet current reaches a minimum value while moving
The phase at which the local minimum value is equal to the phase corresponding to the minimum value
If the difference between the maximum value and the minimum value of the jet current is
Accumulate as contrast in number
Search for the largest contrast in the trust,
The corresponding excitation frequency is determined as the optimal excitation frequency ,
An optimal excitation frequency setting step of outputting an excitation signal of the optimal excitation frequency. 8. The pressurized ink is made n (an integer of 2 or more)
A jet forming step of splitting the continuous jet into ink particles of uniform size in synchronization with the excitation of the vibrator mounted on the nozzle by discharging as a continuous jet from the book nozzle, and in synchronization with the excitation signal of the vibrator A probe pulse generating step of generating a probe pulse, a charging step of charging the ink particles by a probe pulse generated in the probe pulse generating step, and a charge value of the charged ink particles charged in the charging step as a current value. A current detection step of detecting; an A / D conversion step of converting a current value detected in the current detection step into digital data; and an excitation frequency of the excitation signal of M (a positive integer) for the n nozzles in order. )), And sequentially changes the phase between the excitation signal and the probe pulse by 2π / N (N is a positive integer) at the excitation frequency of each step. The digital data converted in the A / D conversion process at each stage for each nozzle is accumulated as jet current waveform data, and the accumulated n × M sets of current waveform data are jetted. The phase corresponding to the minimum value of the current
Extracted, and the excitation signal is delayed with respect to the probe pulse.
The jet current reaches its maximum value while shifting the phase in the direction
And extract the phase
To shift the phase in the direction in which the excitation signal is delayed.
Extract the phase at which the jet current has a minimum value, and reach the minimum value
If the phase is equal to the phase corresponding to the minimum value,
The difference between the local maximum value and the local minimum value
Accumulate as the last, from the accumulated contrast
Contrast whose excitation frequency is common to each jet forming means
Minimum contrast for each jet forming means
Value and obtain the largest value among the minimum values of the obtained contrast.
Optimum excitation frequency corresponding to minimum contrast
It determines the excitation frequency, the optimal excitation frequency setting method which comprises the optimum excitation frequency determination step of outputting the excitation signal of the optimum excitation frequency. 9. The method according to claim 9, wherein the pressurized ink is n (an integer of 2 or more)
A jet forming step of splitting the continuous jet into ink particles of uniform size in synchronization with the excitation of the vibrator mounted on the nozzle by discharging as a continuous jet from the book nozzle, and in synchronization with the excitation signal of the vibrator A probe pulse generating step of generating a probe pulse, a charging step of charging the ink particles by a probe pulse generated in the probe pulse generating step, and a charge value of the charged ink particles charged in the charging step as a current value. A current detection step of detecting; an A / D conversion step of converting the current value detected in the current detection step into digital data; and simultaneously setting the excitation frequency of the excitation signal to M (positive integer) for the n nozzles. The phase between the excitation signal and the probe pulse is switched by 2π / N (N is a positive integer) at the excitation frequency of each stage. The digital data converted in the A / D conversion process at each stage for each nozzle is accumulated as jet current waveform data, and the accumulated n × M sets of current waveform data are jetted. The phase corresponding to the minimum value of the current
Extracted, and the excitation signal is delayed with respect to the probe pulse.
The jet current reaches its maximum value while shifting the phase in the direction
And extract the phase
To shift the phase in the direction in which the excitation signal is delayed.
Extract the phase at which the jet current has a minimum value, and reach the minimum value
If the phase is equal to the phase corresponding to the minimum value,
The difference between the local maximum value and the local minimum value
Accumulate as the last, from the accumulated contrast
Contrast whose excitation frequency is common to each jet forming means
The minimum contrast for each di jet forming means on the execution
Value and obtain the largest value among the minimum values of the obtained contrast.
Optimum excitation frequency corresponding to minimum contrast
It determines the excitation frequency, the optimal excitation frequency setting method which comprises the optimum excitation frequency determination step of outputting the excitation signal of the optimum excitation frequency.