JPS63182153A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To perform favorable multi-gradational recording by using large and small diameter ink droplets, by operating a means for generating a charging voltage for large diameter ink droplets at the time of recording by use of the large diameter ink droplets, operating a means for generating a chaging voltage for small diameter ink droplets at the time of recording by use of the small diameter ink droplets, and performing switching of an ink droplet generating mode during a non-recording period. CONSTITUTION:A sine wave supplied from a high frequency power source 16 to dropletize an ink through excitation of a nozzle 21 is controlled in voltage by a volume control 17 so as to generate small diameter ink droplets, and is controlled in voltage by a volume control 18 so as to generate large diameter ink droplets. A relay 19 selects either one of a large diameter ink droplet exciting voltage sent from the volume control 18 and a small diameter ink droplet exciting voltage sent from the volume control 17, then the selected voltage is amplied by an OP amplifier 20, and is applied to a piezoelectric element 22. Switching a large diameter ink droplet generating mode to a small diameter ink droplet generating mode or vice versa is set in the period for which a non-recording area is detected by a sensor 25, namely, in a non-recording period in a recording operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording device, and more specifically, one nozzle generates two types of ink particles, large and small, and The present invention relates to an improvement of an inkjet recording device that performs multi-tone recording using ink particles.

[Conventional technology]

A technique similar to the inkjet recording device that is the object of the present invention is described, for example, in Japanese Patent Publication No. 54-41329. The two types of ink particles, large and small, are charged and deflected by a control electrode according to a recording information signal.

Recording is performed by controlling the adhesion of ink particles to recording paper.

That is, in the conventional technology described above, large and small diameter ink particles are arbitrarily selected in a state in which large and small diameter ink particles are generated, and these are charged and deflected to form two types of large and small diameter ink particles on a recording medium. Ink particles are combined within the same area to perform multi-tone recording.

[Problems to be Solved by the Invention] However, in the prior art described above, the charging voltage for charging two types of large and small ink particles varies considerably depending on the diameter and mass ratio of the ink particles. For example, if the diameter of the large-diameter ink particles is twice the diameter of the small-diameter ink particles,
The charging voltage for large diameter ink particles requires approximately four times the charging voltage for small diameter ink particles.

Therefore, there is room for improvement in that when large-diameter ink particles are charged, the flight path of small-diameter ink particles is thrown off by Coulomb force or the like, causing adverse effects such as recording disturbances and staining the gutter.

In addition, in the above-mentioned conventional technology, if the timing of charging the ink particles is out of order and the small diameter ink particles are charged with the large diameter ink particle charging voltage, the small diameter ink particles are largely deflected and the control electrode etc. are contaminated. But there is room for improvement.

The present invention has been made in consideration of the above points, and includes:
The purpose is to generate two types of ink droplets, large and small, with a single excitation nozzle, and control the charge of each ink droplet to create '2! In inkjet recording devices that perform recording, it is possible to prevent adverse effects on small-diameter ink particles when charging large-diameter ink particles, and to prevent contamination of control electrodes, etc. due to misalignment of the timing of charging ink particles.
It is an object of the present invention to provide an improved inkjet recording device that can perform good multi-tone recording using ink particles of large and small diameters.

[Means for solving problems]

The purpose is to provide an inkjet recording apparatus that generates two types of large and small ink particles with one excitation nozzle and performs recording by controlling the charge of each ink droplet, as an excitation means for generating ink particles from the excitation nozzle. It has an excitation intensity setting means for selectively setting the excitation intensity to either a mode that generates only large-diameter ink particles or a mode that generates two types of ink particles, large and small, and the large-diameter ink particles and means for generating a charging voltage for using small-diameter ink particles for recording, and when recording large-diameter ink particles, a large-diameter ink particle charging voltage generating means This is achieved by configuring the system so that when the small-diameter ink droplet charging voltage means is operated during recording of small-diameter ink droplets, the generation mode of large and small-diameter ink droplets is switched during a non-printing time during printing.

[Effect]

That is, as is clear from the above description, the excitation intensity setting means, as an excitation means for generating ink particles from one excitation nozzle, sets the excitation intensity to a mode in which only large-diameter ink particles are generated, and a mode in which only large-diameter ink particles are generated, and a mode in which only large-diameter ink particles are generated. Selectively set one of the modes that generate different types of ink particles.

Further, the charging voltage generating means operates the large-diameter ink particle charging voltage generating means when recording large-diameter ink particles, and operates the small-diameter ink particle charging voltage generating means when recording small-diameter ink particles.

Furthermore, the mode switching command device that switches the generation mode of large and small diameter ink particles switches the excitation intensity setting means and the charging voltage generating means described above. Since this is carried out within a certain period of time, there will be no malfunction when switching the ink particle generation mode even if the particle generation mode is disturbed.

〔Example〕

Hereinafter, the present invention will be explained based on an embodiment of the drawings. FIG. 1 is an electric circuit diagram of an inkjet recording apparatus according to the present invention, FIG. 2 is a timing chart of ink particle generation, and FIG. 3 is a gradation chart. FIG. 4 is a diagram illustrating recording and expressing means including a conventional example. FIG. 4 is a diagram sequentially illustrating the process of recording based on the circuit configuration shown in FIG. 1.

Here, the background that led to the creation of the present invention will be briefly explained, although it partially overlaps with the procedure described in the above section [Problems to be Solved by the Invention].

First, in the conventional combination recording of large and small diameter ink particles, recording is performed by arbitrarily selecting large and small diameter ink particles while large and small diameter ink particles are generated. When recording with diameter ink particles,
There is a problem in that small-diameter ink particles have an adverse effect on recording.

Therefore, in order to solve the above problem, two excitation nozzles are prepared, one nozzle is dedicated to recording large diameter ink particles, and the other nozzle is dedicated to recording large and small diameter ink particles. It is conceivable that the positions are within the same area.

However, according to this interjet recording device,
It is necessary to align the two nozzles with extremely high precision, and achieving this requires a very large circle.

Therefore, the present inventors set the number of excited nozzles to one and set the ink droplet generation modes during recording to two, a large-diameter ink droplet generation mode and a large- and small-diameter ink droplet generation mode, and set the above two modes. An inkjet recording apparatus that performs recording by switching has been devised, and according to this, it is possible to perform good recording when recording large-diameter ink particles or when recording small-diameter ink particles.

However, according to the above-mentioned inkjet recording device that was previously invented by the present inventors, the particle generation mode is disturbed when switching the ink particle generation mode, and when recording with large diameter ink particles, small diameter ink particles have a negative effect on recording. It was found that the

In contrast, in the present invention, as described above, the generation mode of large and small diameter ink particles is switched during the non-recording time during recording. When switching modes, there will be no malfunction even if the particle generation mode is disturbed.

In FIG. 1 showing the overall configuration of the apparatus of the present invention, 1 is a line buffer that transfers digital image signals and stores them for each row with a lock, and 2 is a ROM that stores recording patterns.
, 3 is a latch that takes in the image signal stored in the line buffer into ROM2 using a clock, 4 is a counter that sequentially outputs the recording pattern in ROMZ, and 5 and 6 are ROM2
A latch and a pulse width/phase adjustment circuit 7 charge the ink particles based on the recording pattern data output from the latch 5, and 7 converts the digital image signal output from the latch 5 into an analog pulse-like signal that is an ink particle charging signal. D to do
/A converter.

8 is an operational (OP) amplifier that adjusts the signal from the D/A converter 7 to a charge signal voltage for small-diameter ink particles; 9 is a D/A
The signal from converter 7 is adjusted to a charging signal voltage for large diameter ink particles. P amplifier, 10 is a relay that switches the output of the OP amplifiers 8 and 9, 11 is a transistor that amplifies the ink particle charge signal from the OP amplifiers 8 and 9, 12.13 and 14 are the ink particle charge signals amplified by the transistor 11. A clamp circuit and a bias power supply for superimposing a bias voltage for deflection on the clamp circuit 12 and a bias power supply 15 indicate a pair of control electrodes to which a charge signal on which a bias voltage is superimposed is applied by the clamp circuit 12.

16 is a high-frequency power source that is an excitation source for the nozzle 21; 17 is a volume that divides the sine wave output from the high-frequency power source 16 into an excitation voltage for small-diameter ink particles; 18 is a high-frequency power source 16
19 is a relay that switches the excitation voltage for large-diameter ink particles from the volume 18 or the excitation voltage for small-diameter ink particles from the volume 17, and 2o is an ink This is an OP amplifier that amplifies the particle excitation signal.

A piezoelectric element 22 converts the ink ejected from the nozzle 21 into particles, and the piezoelectric element 22 is provided on the nozzle 21 and vibrates in response to an ink particle excitation signal. 25 is a non-recording area on the recording drum 23 (that is, a portion where the recording medium 24 wound around the drum 23 does not exist)
26 is a comparator that binarizes the signal from the sensor 25, 27 is the comparator 26 that
A D-type flip-flop synchronizes the digitized sensor signal with a clock; 28 and 29 are counters and NAND gates that create signals indicating the recording state of large-diameter ink particles or small-diameter ink particles; 31 and 32 are nozzle 1
The diagram shows an OR gate and an inverter that generate signals for controlling motor controllers 1 to 30 for horizontal feeding of the recording head, that is, for recording sub-scanning.

In this embodiment, as will be described later, one line of pixels is recorded while the drum 23 rotates four times, and the line buffer 1 is used to record the next line of pixels until the recording of one line's worth of image signals is completed. Do not import image signals of rows. The gradation recording pattern is stored in ROM2, and the image signal is
Select a pattern as the address of OM 2 and set counter 4.
The selected patterns are sequentially output, and the D/A converter 7 converts them into pulse-like analog signals (ink particle charge signals). The oP amplifier 8 adjusts the signal from the D/A converter 7 to a charging signal voltage for small-diameter ink particles.
Further, the OP amplifier 9 adjusts the signal from the D/A converter 7 to a charging signal voltage for large-diameter ink particles, and the relay 10
selects the output of either OP amplifier 8 or 9. The transistor 11 is for amplifying the ink particle charge signal from the OP amplifiers 8 and 9, and the ink particle charge signal amplified by the transistor 11 has the following characteristics:
Deflection bias voltages from exposed 3 bias power supplies 13 and 14 are superimposed and applied to the control electrode 15.

On the other hand, the voltage of the sine wave from the high frequency power source 16 that excites the nozzle 21 to turn the ink into particles is adjusted by the volume 17 so that small diameter ink particles are generated.
The sine wave from 6 is voltage adjusted to generate large diameter ink droplets at volume 18. And relay 1
9 selects either the excitation voltage for large-diameter ink particles from volume]-8 or the excitation voltage for small-diameter ink particles from volume 17, amplifies it with the OP amplifier 20, and applies it to the piezoelectric element 22. do.

The sensor 25, which is composed of a reflective photointerrupter, detects a non-recording area on the drive 1123 where the recording medium 24 does not exist.2 This signal is binarized by a comparator 26, and then the D After synchronizing with the clock using the type flip-flop 27, the counter 28
The output of the counter 28 is decoded by the NAND gate 29. The signal decoded by N A N D gate 29 is connected to the coil of relay 10.19 via ROM 2 and buffer 33.34 to switch between large diameter ink droplet recording and small diameter ink droplet recording. Therefore, in the present invention, the timing for switching the generation mode of large and small diameter ink particles is performed during the time when the sensor 25 is detecting the non-printing area, that is, during the non-printing time during printing.

Further, the horizontal movement of the recording head on which the nozzles 21, the control electrodes 15, etc. are mounted, that is, sub-scanning, is performed by, for example, a pulse motor, and the sub-scanning is controlled by a sub-scanning motor controller 30. Note that the sub-scanning motor controller 1 and the roller 30 have the output of the D-type flip-flop 27 inverted by the inverter 32 and the NA
It is activated by a signal obtained by combining the output signal of the ND gate 29 with the OR gate 31.

Further, in this embodiment, a relay 10 is used as a means for switching the output signals of the OP amplifiers 8 and 9, and a relay 19 is used as a means for switching the output signals of the volume 17.18.
Although the case where the switch is used has been exemplified, instead of this, for example, an analog switch may be used.

In Figure 2, which shows the timing of ink particle generation, (
A) is the output signal of the D type flip-flop 27, (B
) is the output signal of the NAND gate 29, (C) is the output signal of the OR gate 31, (D) is the output signal of the ○P amplifier 20, (E) is the timing of generation of ink particles, and (F) is the output signal of the OR gate 31. The ink particle charge signal amplified by the transistor 11 is shown in FIG.
, g is in h state. (I3) counts the non-recording time part in (A), sets the first to third lines (see the explanation in FIG.
w state, If i gh state is set to record small-diameter ink particles, and LOν state is set to record large-diameter ink particles. In addition, in FIG.
) rises, that is, immediately after entering the non-recording time, switching between the Light state and the Low state does not necessarily have to be performed immediately after entering the non-recording time, and it is sufficient to switch within the non-recording time. ), l <C> is a control signal for performing sub-scanning, and is Low.
drive the pulse motor (the pulse motor that moves the recording head laterally). Therefore, in the illustrated embodiment, as is clear from the explanation of FIG. 4, which will be described later, sub-scanning is performed during recording of small-diameter ink particles (first to third lines), but large-diameter ink particles When switching to recording (between the third and fourth lines), sub-scanning is not performed.

That is, in this embodiment, one pixel is formed by a 3×33 matrix (see the explanation of FIG. 3 described later).
This method first records three lines with small-diameter ink particles, and then records with large-diameter ink particles in the same area of these three lines.

(D) is an excitation waveform, and the excitation voltage for large and small diameter recording is switched in accordance with the signal (B).

(E) shows the ink droplet generation timing generated by the excitation signal in (D), and (F) shows the charge signal of the ink droplets. When large and small diameter ink particles are generated, recording with small diameter ink particles is performed using small diameter ink particles. Recording with large-diameter ink particles is performed using a voltage for charging small-diameter ink particles based on the generation timing of the particles, and recording with large-diameter ink particles is performed using a voltage for charging large-diameter ink particles based on the generation timing of large-diameter ink particles.

In FIG. 3, which shows the gradation recording expression means including the conventional example, (a) shows a dot recording pattern within the minimum recording range, (
b) is a diagram showing a specific example of configuring one pixel by combining (a), (c) is a diagram illustrating an example of the configuration of one pixel according to the prior art, and (d) is the pixel shown in (b). FIG. 2 is a diagram showing the pixel configuration for actually recording, and the recording dots allocated within the minimum recording range in (a) are at most three small diameter dots,
It has one large diameter, and as a result, the number of gradation expressions within the minimum recording range is a total of 8 gradations from pattern 0 to pattern 7.

Furthermore, as shown in (b), if the dot recording pattern in (a) is made into a 3×3 matrix and this is taken as one pixel, 64 gradations can be expressed.

(c) shows a configuration example of 64 gradations per pixel according to the prior art, and according to this, a maximum of 64 small-diameter ink particles must be recorded within one pixel. In contrast, in the case of the present invention, focusing on (b), the maximum number of ink particles recorded within one pixel is 27 small-diameter ink particles and 9 large-diameter ink particles, a total of 36. This will speed up recording. Note that by increasing the ratio of the large ink droplet diameter to the small ink droplet diameter, the number of ink droplets allocated within the minimum recording range can be changed and the number of gradations can be increased. White spots become noticeable, so the ratio of large and small diameter ink particles is
It is appropriate to set the ratio to be about 2:1 and the number of dots allocated within the minimum recording range to be about 1 large-diameter ink droplet and 3 small-diameter ink droplets. By the way, when actually recording the pixel shown in (b) (when the small-diameter ink droplet recording is performed in three scans and the large-diameter ink droplet is recorded in one scan), the configuration of one pixel is as shown in FIG. As shown.

It is not a square pixel, but a diamond-shaped pixel, as shown in (d). The reason for this is as follows: large-diameter ink particles have 1
This is because it is necessary to print all within one pixel by scanning, and in order to perform three deflection printing, a deviation corresponding to one small-diameter ink droplet is generated in the vertical direction. The reason why the recording arrangement of small-diameter ink particles in ('d) is different from that in (a) and (b) is that the pixels are diamond-shaped, as described above. In other words, when one pixel is diamond-shaped, the gaps between large-diameter particles become elongated, and in the arrangements of (a) and (b), it is elegant to eliminate the gaps described above, and in order to improve this, ( As shown in d), the recording arrangement (inclination) of small-diameter ink particles is reversed to that in (a) and (b).

In FIG. 4, which shows a step-by-step process of recording based on the circuit configuration shown in FIG. 1, a case is illustrated in which all large and small diameter ink particles are recorded within one pixel. Also, the fourth
In the figure, it is assumed that the rotational direction of the drum, which is the main scanning, is rotating from the right side to the left in the drawing, and the feeding of the recording head, which is the sub-scanning, is performed from the top to the bottom of the drawing. Furthermore, the symbols (1) to (6) in FIG. 4 correspond to the symbols (1) to (6) in FIG.

In FIG. 4, to print one pixel on the first line (1), first, during the non-printing time during printing, the print head is moved to the middle between the first and second lines by sub-scanning, Recording is performed sequentially using small-diameter ink particles in a direction opposite to the rotational direction of the drum. 1
Once the recording of the first line is completed, next the recording of the second line (2
), the recording head is moved to the middle between the second and third lines during the non-recording time, and the recording is performed sequentially from left to right in the same manner as the first line. The record on the third line (3) is also
In the same way as in (1) and (2), move the recording head to the middle between the third row and the first row of the next pixel during the non-recording time, and
Record the rows sequentially from left to right. This completes the recording of small-diameter ink particles for one pixel, but when recording large-diameter ink particles overlappingly on this one pixel, the generation mode of large and small-diameter ink particles must be switched during the non-recording time. , and without moving the print head (that is, by moving the print head to an intermediate position between the third row and the first row of the next pixel), the large-diameter ink particles are deflected three times, and the large-diameter ink particles are deflected three times, and the ink particles for one to three rows are deflected. Record all at once ((4), (5) and (6)
)), the recording for one pixel is completed, and the recording from (1) above is sequentially repeated in order to record the next pixel.

According to the present invention, as described above, since the generation mode of large and small diameter ink particles is switched during the non-recording time during recording, when the ink particle generation mode is switched, even if the particle generation mode is Even if disturbance occurs, there will be no malfunction.

〔Effect of the invention〕

The present invention is as described above, and as is clear from the explanation of the illustrated embodiments, according to the present invention, two types of ink droplets, large and small, are generated by one excitation nozzle, and each ink droplet is controlled to be charged. In an inkjet recording device that performs recording, it is possible to prevent adverse effects on small-diameter ink particles when charging large-diameter ink particles, and to prevent contamination of control electrodes, etc. caused by timing errors in charging ink particles. It is possible to perform good multi-tone recording using particles.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, FIG. 1 is an electric circuit diagram of an inkjet recording apparatus according to the present invention, FIG. 2 is a timing chart of ink particle generation, and FIG. 3 is a conventional example of gradation recording expression means. FIG. 4 is a diagram sequentially showing the process of recording based on the circuit configuration shown in FIG. 1. 8 and 9...○P amplifier, 10...relay, 17
and 18...volume, 19...relay, 25
...Sensor, 26...Comparator, 28...Counter. (Other 1.7+)ゝ・! ' No. 30 (a)

Claims (1)

[Scope of Claims] 1. Means for guiding ink to one excitation nozzle to generate ink particles of two types of large and small diameters, charge deflection means for charge deflection of large diameter ink particles and small diameter ink particles, and ink particles an excitation means for generating ink particles from the excitation nozzle, in an inkjet recording apparatus that combines two types of ink particles, large and small, on a recording medium and performs multi-gradation recording; and an excitation intensity setting means for selectively setting the excitation intensity to either a mode that generates only large diameter ink particles or a mode that generates two types of ink particles of large and small diameters,
and means for generating a charging voltage for using large-diameter ink particles for recording, and means for generating a charging voltage for using small-diameter ink particles for recording, and when recording large-diameter ink particles, the large-diameter ink operating the particle charging voltage generating means;
An inkjet recording apparatus characterized in that when a small diameter ink particle charging voltage means is operated during recording of small diameter ink particles, the generation mode of large and small diameter ink particles is switched during a non-recording time during recording. 2. In the invention described in claim 1, the generation mode of large and small diameter ink particles is switched by using a plurality of main scanning periods as one unit, one of which is set as a recording mode using large diameter ink particles, and the other. In order to use the recording mode using small-diameter ink particles multiple times, the charging voltage generating means issues a command to that effect during the non-recording time and uses the ink particles for recording, and the charging voltage generating means is configured to perform the same scanning within one unit as described above. An inkjet recording device configured to generate a voltage that deflects each ink droplet within a region.