JPS6321624B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention jets pressurized ink from an ink jet orifice, adds vibrations of a certain period to the jetted ink before or when it leaves the ink jet orifice, and uses this vibration to eject pressurized ink. The ink is separated into ink particles at a position where the ink has traveled a predetermined distance, and at the time of separation into ink particles, a charging voltage corresponding to the printing position is applied according to the image signal, so that the charging level is gradually varied. In particular, this invention relates to a deflection control inkjet recording device that forms charged ink particles and deflects them using a deflection electric field, ink particles with a charge amount below a predetermined amount are captured by a gutter, and other ink particles collide with recording paper. Although not intended to be limited to this, the present invention relates to a multi-nozzle deflection control inkjet recording apparatus that arranges a plurality of ink jetting ports at a predetermined pitch and divides and records a predetermined width with ink jetted from each ink jetting port.

In this type of inkjet recording, for example, ink ejected from one fine nozzle is
The ink particles are deflected in 40 stages, one line width (deflection width) is recorded by these 40 stages, and even if the ink particles are uncharged or charged, the amount of charge less than a predetermined amount is captured by the gutter. The recording pitch of ink particles with 40 levels of charge on the recording paper and the ink particles with 40 levels of charge are 1
Even if the charging voltage level applied to the charging electrode is a predetermined value and the deflection voltage applied to the deflection electrode is a predetermined value, the recording position to be grouped is determined by the distance between the deflection electrode and the recording paper, the distance between the deflection electrode and the recording paper, gaps etc.
It changes depending on the mechanical dimensions, and the recording width may be narrow or wide. Using one nozzle, move it in the direction
Mechanically scanned in X (deflection direction of ink droplet is Y-
In inkjet recording (Y), if the recording width (deflection width) of one scan is narrow, unrecorded white stripes (in the X-X direction) will occur between the recording widths of the previous and subsequent scans. When the recording width of one scan is wide, the scanning recording widths of the previous and subsequent scans overlap, resulting in black stripes (X-X direction).
will occur.

In multi-nozzle inkjet printing, in which multiple nozzles are lined up and simultaneously print on each section of the recording paper, printing by adjacent nozzles may be discontinuous (white stripes in the Y-Y direction) or overlap (Y-Y direction).
- Black streaks in the Y direction) Recorded image quality deteriorates.

JP-A-48-74115 and JP-A-51-91628
The publication discloses that by shifting the recording position by shifting up or down the deflection voltage as a whole,
We are trying to improve the above problems. However, such an adjustment simply adjusts the deflection voltage, so if nozzles A, B, and C are lined up in this order, the recording of nozzle A and the recording of nozzle B will partially overlap, so this If the deflection voltage assigned to nozzle B is increased in order to improve this, the recordings of nozzles A and B are preferably continuous, but the recordings of nozzles B and C may end up overlapping. On the contrary, nozzle A
If the deflection voltage assigned to nozzle B is lowered, the recordings of nozzles A and B will preferably continue, but white spots will occur between the recordings of nozzles B and C. It may occur. These problems tend to occur when there are variations in nozzle pitch.

The present invention aims to improve the above-mentioned problems.

In the present invention, in order to improve this problem, the spread of the entire recording width by one nozzle is adjusted. For this purpose, the deflection control inject recording apparatus of the present invention includes a charging voltage signal generating means which is a signal generating means for generating a charging voltage signal with a number of stages m larger than a predetermined number n of deflection stages, a pitch specifying means for specifying a dot pitch, dot pitch setting means for specifying n stages of the m stages of charging voltage signals at pitches designated by the pitch designation means;
A charging device is used which includes means for applying a charging voltage corresponding to the charging voltage signal specified by the dot pitch setting means to the charging electrode.

According to this, the signal generating means can generate a charging voltage signal with a number of stages m larger than the predetermined number n of deflection stages, and the dot pitch setting means can change the dot pitch from the initial value m at the pitch specified by the pitch specifying means. A charging voltage signal of a predetermined number of deflection stages n stages is specified from charging voltage signals up to the stage, and a charging voltage corresponding to the specified charging voltage signal is applied to the charging electrode, so that the recording dot pitch is specified by the pitch specifying means. It becomes what it is. That is, the recording dot pitch can be adjusted using the pitch specifying means. Therefore, the recording width (total deflection width) can be adjusted wide or narrow using the pitch specifying means. For example, in the case of multi-nozzle recording, this allows you to adjust the recording width to a narrow width when the nozzle pitch is fluctuating widely or narrowly. For nozzles that must record, the dot pitch is narrowed to narrow the overall recording width, and for nozzles that must record a wide width, the dot pitch is widened to widen the overall recording width, so that recording by adjacent nozzles is It is possible to create a smooth continuation without overlapping and without white spots. one nozzle
In the mode of repeatedly scanning in the X direction, the recording width can be adjusted so as to eliminate white spots and overlapping recordings (black stripes) between adjacent scans.

It may not be possible to completely eliminate black streaks and white streaks by adjusting the recording width for one nozzle alone. For example, when the orientation of the nozzles is tilted, it is preferable to adjust the position of the entire recording width in addition to adjusting the recording width, so that the recordings of adjacent nozzles can be smoothly continued.

Therefore, in a preferred embodiment of the present invention, a deflection voltage source that applies a deflection voltage to the deflection electrode is provided with a deflection voltage adjustment means, and the deflection voltage is adjusted by this means.
Adjust the entire recording position of one nozzle.

Other objects and features of the invention will become apparent from the following description of embodiments with reference to the drawings.

FIG. 1 mainly shows the mechanical parts of an embodiment of the present invention. This is a multi-nozzle inkjet recording device, and numeral 10 is an ink jetting head. The ink ejecting head 10 is mainly composed of a flow path member 11 forming a common ink flow path, a vibrator support frame 12 forming an excitation space, and a nozzle plate holder 13. A plurality of electrostrictive vibrators 12ai are fixed to the bottom wall of the support body 12, and constant frequency pressure vibrations are applied to the pressurized ink in the inner space of the support frame 12 by synchronized constant frequency excitation of these vibrators. Holder 1
3, the support 12 is placed at a fixed pitch (for example, 5 mm).
A plurality of ink channels 13ai are opened which communicate with the inner space of the holder 13, and a nozzle plate 14 with fine ink jet ports 14ai opened at the same pitch as these ink channels 13ai is bonded to the surface of the holder 13. ing. In one example, the ink jet port 14ai is
There are 42 heads, and their arrangement pitch is 5 mm, allowing one head to record a width of 42 x 5 mm = 210 mm.

A charged electrode plate 20 is arranged in front of the nozzle plate 14, a charged detection electrode plate 40 is arranged in front of it via a shield plate 30, and a shield plate 5
0, the deflection electrode unit 60 is placed, and the gutter 70a is placed in front of it.
The electrode plates 20 and 40 and the shield plates 30 and 50 each have inverted U-shaped openings with a number equal to the number of ink jet ports 14ai, and the electrode plates 20 and 40 have printed electrodes on the inner surfaces of these openings. 2
0aj and 40aj are formed, and are individually drawn out along the surfaces of the electrode plates 20 and 40. Deflection electrodes are deposited on the front and back surfaces of the deflection electrode plate 60a of the deflection electrode unit 60, and are connected to conductor wires 61 and 62, respectively.

As shown by the dashed line in FIG. 1, there is a gutter 70a erected in the ink collection frame 70 at a position where ink is ejected from each ink ejection port 14ai and uncharged (non-recording level) ink particles collide with each other. do.

A charging voltage whose level varies in, for example, 40 steps is applied to the charging electrode 20aj in accordance with the image signal. For example, when recording straight lines, the ink ejected from the ink jet port
A charged electrode 20 is connected to each of the 40 particles.
voltage pulses from the first level to the 40th level are applied to aj, and each of the 40 ink droplets is
They are respectively charged from the level to the 40th level, are deflected by the electric field between the deflection electrodes, and pass through the 1st to 40th deflection trajectories, respectively, in the arrangement direction of the gutter 70a (hereinafter referred to as the main scanning direction or the X-X direction). Dot printing is recorded. The recording paper is fed continuously or intermittently in the Y-Y direction orthogonal to the XX direction. Since the application of the charging voltage is controlled according to the image signal and the recording paper is fed, ink is printed dot by dot on the recording paper in the X-X direction and the Y-Y direction. .

FIG. 4 mainly shows the structure of the mechanism section of another embodiment of the present invention. This is a cylindrical electrostrictive vibrator 15ai with one end fixed to the holder 13. In this case, pressure vibrations of a constant frequency are applied to the pressurized ink while it passes through the electrostrictive vibrator 15ai. The other configurations are the same as those shown in FIG. 1 described above.

FIG. 6a shows the configuration of a charging device according to an embodiment of the present invention. Note that the charging device shown in FIG.
A charging voltage is applied to the charging electrode 20aj shown in FIG.

In FIG. 6a, 80 ₁ , 80 ₂ , 80 ₃ ,...
... is a charging device that applies a charging voltage to each of the charging electrodes, and these devices all have the same configuration and are in one-to-one correspondence with each of the charging electrodes 20aj. ) is applied. The charging device ₈₀₁ will be explained below.

In this example, a counter _CO11 is used as a signal generating means for generating a charging voltage signal with a number of stages m=256 which is larger than a predetermined number of deflection stages n=40, and this constitutes the charging voltage signal generating means. In addition, switches SW5 to SW can be used as a dot pitch specifying means.
9 and use a counter as a dot pitch setting means.
CO2 ₁ , decoder DE ₁ , AND gate A11~A
15. Using the OR gate R1, the counter CO3 ₁ , the AND gate A16, and the flip-flop _F1 , a charging timing pulse is generated in the phase setting circuit _PS1 in synchronization with the output pulse of the OR gate R1, and this pulse is (when the image signal indicates recording) AND gates A21 to A28,
It is converted into a charging voltage (analog voltage) by the D/A converter DA ₁ and the high voltage amplifier AMP ₁ , and then the charging electrode 20a ₁
I am trying to apply it to

In this example, the ink jetted from one ink jetting port is deflected in 40 steps to record 40 dots. Therefore, a shift register _SH1 is provided that inputs and serially outputs image signals for 40 pixels in parallel. The counter _CO11 that determines the charging voltage level is an 8-bit counter that can perform 256 counts of 40 or more in order to make the level difference between dots adjustable.

The output analog voltage of D/A converter DA ₁ is output by an amplifier.
AMP ₁ and an amplified voltage is applied to charging electrode 20a ₁ .

On the other hand, the clock pulse ₂ applied to the counter CO11 is also applied to the second counter _CO21 .
The count code of the second counter CO2 ₁ is applied to the decoder DE ₁ , and each of the outputs 2 to 6 of the outputs 0 to 7 of the decoder DE ₁ is applied to the AND gate A11.
~A15 is applied to one input terminal of each of the switches SW5 to SW9, and the other input terminals are connected to each of the switches SW5 to SW9, and the outputs of the AND gates A11 to A15 are connected to the phase setting circuit PS1 via the OR gate _R1.
is given as a printing synchronization signal to
It is applied to the clear input of CO2 ₁ via OR gate R2. When switch SW5 is closed,
Since AND gate A11 is conductive (on),
The output of the OR gate R1 has the pulse waveform shown first from the top in FIG. 6b. Similarly, SW6~SW
9 are closed, the OR gate R1 outputs the pulses shown in the third to sixth positions from the top in FIG. 6b, respectively. That is, when the switch SW5 is closed, a pulse obtained by dividing the clock pulse 2 by half (with twice the period) is sent to the OR gate R1.
is output from 3 when switch SW6 is closed.
When SW7 is closed, the pulse is 4 times the period; when SW8 is closed, the pulse is 5 times the period; and when SW9 is closed, the pulse is 6 times the period.
A pulse with twice the period is output from OR gate R1.

When phase setting circuit PS ₁ is commanded to perform a phase search, it sets k sets of search pulses based on clock pulse 1 (FIG. 6c) with a period that is a fraction (1/k) of the period of clock pulse 2. 1 to k are created, and the search pulses of each set 1 to k are switched and output every time a predetermined number of clock pulses 2 occur. This is done by outputting one search pulse of a certain group i (i = 1 to k) every time the OR gate OR1 outputs one pulse, and when outputting a phase search pulse of a certain group i. When the charge of the ink particles is detected by the charge detection electrode _40a1 , the charge pulses at the time of printing and recording are divided into the i-1st set, the i-th set, and the i+1th set.
OR of the phase search pulses of the set (the pulse width is three times the position search pulse, the period is the same as the phase search pulse, and the pulse width is expanded three times around the i-th set of phase search pulses) pulse). When the phase setting circuit _PS1 is instructed to "record", it outputs the charged pulse to the AND gate A17 in synchronization with each pulse outputted from the OR gate R1. AND gate A17 transfers that pulse (recording charge pulse) to AND gate A17.
21 to A28. Therefore, the converter
The output voltage of DA ₁ applies a charging voltage to the amplifier AMP ₁ when the recording charging pulse is at a high level "1".

The output pulse of the phase setting circuit _PS1 , that is, the recording charge pulse, is counted by the third counter _CO31 , and when the count value of the counter _CO31 reaches 40,
The output of AND gate A16 becomes "1" and flip-flop _F1 is reset. Flip-flop _F1 is set by a reset signal and applies a high level "1" Q output to AND gate A17 while 40 recording charge pulses are applied to AND gate A17. And gate A17 has
The output of the shift register _SH1 , that is, the image signal (recording: "1", non-recording: "0") is applied. The shift register _SH1 is serially shifted by the output pulse of the OR gate R1. Therefore, while reading image signals for 40 pixels, the output of AND gate A17 becomes "1" in synchronization with the recording charge pulse and in accordance with the image signal, and when this output is "1", AND gate A21 ~The output code of the counter _CO11 is applied to the converter _DA1 through A28, and the output voltage of the converter _DA1 is at a high level only while the image signal is "1" and the recording charge pulse "1" appears. (Analog voltage corresponding to the count code of counter CO1 ₁ ). Note that a sine wave excitation voltage (FIG. 6c) is applied to the electrostrictive vibrator _12a1 in synchronization with the clock pulse 2 and having the same period. As a result, the ink ejected from the ink ejection port _14a1 is ejected at one rate per period of the clock pulse 2.
Separates into individual ink particles. That is, ink particles are generated at the same speed (particles/sec) as the frequency of clock pulse 2.

With the above configuration, the printing dot pitch of the ink jetted from the ink jetting port _14a1 can be controlled by the switch.
Wide and narrow adjustments can be made by selectively closing SW5 to SW9. That is, when SW5 is closed, a printing synchronizing pulse with a cycle twice that of clock pulse 2 is output from OR gate R1, and each printing synchronizing pulse produces one ink droplet (continuously ejected ink droplets). Since the 40 dots are charged at a charging voltage in the range indicated by A in FIG. 6b, the difference in the amount of charge between the dots is small, and the printing dot pitch is extremely small. Therefore, the recording width of 40 dots is narrow. When SW6 is closed, a printing synchronization pulse with a period three times that of clock pulse 2 is output from OR gate R1.
Since each printing synchronization pulse charges one ink droplet (two consecutive ink droplets), the 40 dots are charged with a charging voltage in the range indicated by B in Figure 6b. , the difference in charge amount between dots is relatively small, and the printing dot pitch is quite small. Therefore, the recording range of 40 dots is quite narrow. On the other hand, when SW9 is closed, a printing synchronizing pulse with a cycle six times that of clock pulse 2 is output from OR gate R1, and each printing synchronizing pulse produces one ink droplet (continuous ejection). Since the 40 dots are charged with a charging voltage in the range shown by E in FIG. 6b, the difference in the amount of charge between the dots is large, and the printing dot pitch is large. Therefore, the record range of 40 dots is wide. When one of the other switches SW7 or SW8 is selected and closed, the 40 dots are charged with a charging voltage in the range shown as C or D in FIG. The recording width of the dot is a value between the value when SW5 is closed and the value when SW9 is closed. In this way, the dot pitch can be adjusted wide or narrow as shown in Figure 5a.

Therefore, when the nozzle pitch is wide or narrow,
In a charging device assigned to a nozzle that has to record a narrow width (divided area), SW5~
For a charging device assigned to a nozzle that must narrow the dot pitch with SW9 and record a wide width, widen the dot pitch with SW5 to SW9 to prevent white spots (white streaks) between recordings of adjacent nozzles due to the wide and narrow nozzle pitch. Alternatively, adjustments can be made so that there are no duplicate records (black streaks).

However, due to misalignment of the nozzle jet direction, etc.
If the recording area is misaligned, turn the switch
It may be impossible to adjust the width of the recording area of the central nozzle so that it does not separate from, and does not overlap, the recording area of the nozzles on both sides, only by adjusting SW5 to SW9.

Therefore, in this embodiment, the deflection voltage source that applies the deflection voltage to the deflection electrode is configured as shown in _FIG . ₂ , _ES3
I am trying to adjust it by... By switching the switch ESi to the high voltage side, the amount of deflection of the entire ink particles ejected from the nozzle 14ai and charged in stages 1 to 40 increases, and the entire recording of the nozzle 14ai moves to the high deflection side. By switching the switch ESi to the low voltage side, the entire recording of the nozzle 14ai moves to the low deflection side.

For example, when using a recording head formed with 42 ink ejection orifices, and assuming that the vertical recording positions of all the ejection orifices are the same (same height), each of the 42 sets of charging devices 80 ₁ to 80 ₄₂ Switch SW5~
With SW9, adjust the recording width of 40 dots for each injection port to be wide or narrow (for example, dotted line, solid line, one-dot chain line, etc. in Fig. 5a) according to the width of the injection port interval, and switch ES ₁ and ES _2. , ES ₃ , ..., the deflection voltage is adjusted to eliminate gaps and overlap between recordings of adjacent nozzles, and the recording position of each nozzle with a width of 40 dots is adjusted.
The recording of ink ejected from each ink ejection port can be smoothly aligned in a continuous straight line without all the dots overlapping.

When the dot pitch is set as shown by the solid line in FIG. 5a, the recording will be a standard pitch recording as shown in FIG. 5b, for example. When the dot pitch is set as shown by the dashed line in FIG. 5a, high-density recording is achieved as shown in FIG. 5c.
When the dot pitch is set as indicated by the dotted line in FIG. 5a, low-density recording is achieved as shown in FIG. 5d.

For example, as shown in FIG. 2, the intention is to record each nozzle so that the records of adjacent nozzles are not separated from each other and do not overlap.
As shown in FIG. 3, when the recording of nozzle 2 shifts to the nozzle 3 side and the recording of nozzle 3 also shifts to the nozzle 4 side, for example, the charging voltage applied to the deflection electrode 60a ₃ by the switch ES ₃ corresponding to the nozzle 3 of,
The recording of nozzle 3 is adjusted so that it does not overlap with the recording of nozzle 4, but is in contact with it, and then the deflection voltage applied to the deflection electrode 60a ₃ is changed by the switch ES ₂ corresponding to nozzle 2 so that the recording of nozzle 2 matches the recording of nozzle 3. Adjust so that it does not overlap with, but touches, the record. This results in
It is sufficient if the recording of nozzle 2 is in contact with the recording of nozzle 1 and does not overlap. However, the recording of nozzle 2 may be separated from or overlap the recording of nozzle 1. In these cases, the recording dot pitch of at least one of nozzles 1, 2, and 3 is adjusted using switches SW5 to SW9, and if necessary, the recording position is adjusted using switches ES ₁ , ES ₂ , and ES ₃ as shown in FIG. Adjust so that the recordings of each nozzle do not overlap or separate. In this way, not only the recording position deviation but also the dot pitch can be adjusted, so when recording by one nozzle cannot be smoothly continued by adjusting the recording position alone, such as when the nozzle pitch is wide or narrow, recording by one nozzle can be adjusted. It has the great advantage of being able to adjust the width (dot pitch) and achieve good continuity.

Next, to explain a modified example, the switch ES ₁ ,
There is little need to change the opening/closing settings of ES ₂ , ES ₃ , . . . and SW5 to SW9 after completing the device assembly and adjusting the recording pitch and deflection position. Therefore, these switches 9 may be replaced with wire connections, solder connections, diode connections, or resistance connections instead of being used as dip switches. Of course, other memory means such as a semiconductor memory may be used, and other switch configurations such as a plug-in switch may also be used.

As described above, according to the present invention, it is possible to electrically adjust the recording width of ink ejected from one ink ejecting port and the recording position as necessary for each ejecting port in accordance with the completed recording head. . Therefore, when a multi-nozzle ink ejecting head is used, the rate at which finished nozzle plates and recording heads are discarded is extremely reduced, greatly contributing to improved yield. One or several nozzles are used to scan and drive this in a direction perpendicular to the recording paper feeding direction Y-Y, and the deflection direction is set to Y-Y. One nozzle scans a recording width of, for example, 40 dots ( Even in the mode in which lines (rows) are recorded, adjustments can be made so that white spots or black streaks do not occur between each recording of adjacent scans. In other words, adjustments can be made to obtain high-quality recording.

[Brief explanation of the drawing]

FIG. 1 is a perspective view mainly showing the structure of a mechanical part of an embodiment of the present invention. 2 and 3 are plan views schematically showing, on an enlarged scale, recording by the inkjet recording apparatus shown in FIG. 1. FIG. Figure 4 shows
FIG. 3 is a perspective view mainly showing the structure of a mechanism section of another embodiment of the present invention. FIG. 5a is a graph showing the recording dot pitch that can be set in one embodiment of the present invention. FIG. 5b is a plan view schematically showing the recording dot distribution when recording is performed with the dot pitch shown by the solid line in FIG. 5a. FIG. 5c is a plan view schematically showing the recording dot distribution when recording is performed at the dot pitch indicated by the dashed line in FIG. 5a. FIG. 5d is a plan view schematically showing the recording dot distribution when recording is performed with the dot pitch shown by the dotted line in FIG. 5a. FIG. 6a is a block diagram showing the configuration of a charging device according to an embodiment of the present invention, which is used in combination with the mechanism shown in FIG. 1 or 4. FIG. Chapter 6b
The figure and FIG. 6c are time charts showing electrical signals of various parts of the circuit shown in FIG. 6a. FIG. 6d is an electrical circuit diagram showing the configuration of a deflection voltage source according to an embodiment of the present invention. 10... Recording head (ink ejecting head), 1
2ai, 15ai...electrostrictive vibrator, 14...nozzle plate, 14ai...ink jet port (fine nozzle),
20ai... Charged electrode (charged electrode), 40ak... Charged detection electrode, 60a... Deflection electrode plate (deflection electrode), 70a... Gutter (gutter), 80 ₁ , 8
0 ₂ , 80 ₃ , ...Charging device (charging device), CO1 ₁
... Counter (signal generation means), ES ₁ , ES ₂ , ES ₃
...Switch (recording position adjustment means), SW5 to SW
9...Switch (dot pitch designation means), CO2
₁ , CO3 ₁ ...Counter, DE ₁ ...Decoder, A
11~A17...and gate, R1, R2...
OR gate, F ₁ ... flip-flop, CO2 ₁ ,
CO3 ₁ , DE ₁ , A11 to A17, R1, R2, F ₁
...(dot pitch setting means), A21 to A28
...and gate, DA ₁ ...D/A converter,
AMP ₁ ...High voltage amplifier, A21 to A28, DA ₁ ,
AMP ₁ (means for applying a charging voltage corresponding to the charging voltage signal specified by the dot pitch setting means to the charging electrode).

Claims (1)

[Scope of Claims] 1. An ink ejection head that ejects ink from a fine nozzle, a charging electrode that charges the ejected ink,
A deflection electrode that applies a deflection electric field to charged ink, a gutter that captures ink that is less than a predetermined charge, a charging device that applies a voltage corresponding to an image signal to the charging electrode, and a deflection voltage source that applies a deflection voltage to the deflection electrode. In the deflection control inkjet recording apparatus, the charging device includes: voltage signal generating means for generating a charging voltage signal with a number m of stages greater than a predetermined number n of deflection stages; pitch designating means for designating a dot pitch; Dot pitch setting means for specifying n stages of the m stages of charging voltage signals at a pitch specified by the pitch specifying means; and a charging voltage corresponding to the charging voltage signal specified by the dot pitch setting means to be applied to the charging electrode. A deflection-controlled inkjet recording device, comprising: means for applying an ink jet. 2. The deflection-controlled ink jet recording apparatus according to claim 1, wherein the deflection voltage source includes deflection voltage adjusting means for adjusting the deflection voltage applied to the deflection electrode.