JP3072792B2 - Ink jet recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, and more particularly to an ink jet recording apparatus which drives a recording head in accordance with a recording mode to control a discharge amount.

[0002]

2. Description of the Related Art In recent years, OA devices such as computers, word processors, and copying machines have become widespread, and a number of recording methods for these recording devices have been developed. The ink jet recording apparatus has an excellent feature that high definition is easy, high speed, excellent in quietness, and inexpensive as compared with other recording methods.

In an ink jet recording apparatus, paper, OHP
Various recording modes are prepared in addition to the simple one-scan recording mode for the purpose of preventing the problem of ink fixability on a recording medium such as a film and the density unevenness inherent to the recording head.

Among such print modes, multi-pass printing, in which the same print head scans the same area on a print medium a plurality of times to perform printing, is widely used for various purposes. In particular, when performing color recording using a plurality of recording heads having different ink colors, one scan is required to print all the recording data at once so that the ink does not overflow on the recording medium and bleed. Is printed in a houndstooth check pattern and is printed a plurality of times, thereby performing a thinned-out multi-pass printing to finish an image corresponding to all print data. Further, even in the case of single-color recording, the following printing method may be used as a modification of the thinned-out multi-pass printing. For example, in a print head composed of a plurality of nozzles, density unevenness unique to the print head due to a difference in ejection characteristics between nozzles may be observed.In order to make such unevenness less noticeable, half of all print data is printed by the first nozzle group. Then, a method of recording the other half by the second nozzle group is also used.

[0005]

In the above-described thinning multi-pass printing, the density of a recorded image may be lower than that in a case where printing is performed at a time without thinning (one-pass printing). This phenomenon varies in degree depending on the type of recording medium, but is generally not likely to occur on coated paper coated with an ink receiving layer and is found on uncoated paper such as PPC paper that has not been subjected to special processing. Often. Although the details of the mechanism of this phenomenon are unclear, among the ink receiving characteristics, the correlation with the ink absorption speed is strong, and paper with poor ink fixability is more likely to occur. Since this phenomenon relates to ink absorption into a recording medium such as paper, there is also a correlation with the ink composition. Thinning-out multi-pass printing is required for paper that is difficult to fix, but such papers tend to cause a density reduction in thinning-out multi-pass, which is a major problem.

In view of the above, the present invention has been made in view of the above, and provides an ink jet recording apparatus capable of preventing a decrease in density in thinned-out multi-pass printing and recording a good image according to a recording medium. The purpose is to:

[0007]

For this purpose, the present invention provides a thinning multi-pass print mode in which the number of print head scans for the same print area is controlled and print data is divided and printed sequentially. A print mode control unit that switches between a one-pass print mode in which all print data is printed by head scanning, and an ejection amount control unit that controls an ink ejection amount; By controlling the ejection amount control means so that the amount is larger than the total ink amount in the one-pass print mode, it is possible to reduce the density decrease in the thinned-out multi-pass print mode, thereby achieving good image recording on various print media. Can be performed.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a schematic view of an ink jet recording apparatus to which the present invention can be applied. Here, C is an ink jet cartridge, which has an ink tank section above, a recording head 23 (not shown) below, and a connector for receiving a signal for driving the recording head 23 and the like. . A carriage 2 positions and mounts four cartridges C1, C2, C3, and C4 (each containing ink of a different color, for example, yellow, magenta, cyan, and black).
Further, a connector holder for transmitting a signal for driving the recording head 23 and the like is provided, and is electrically connected to the recording head 23.

A scanning rail 11 extends in the main scanning direction of the carriage 2 and slidably supports the carriage 2.
Reference numeral 2 denotes a drive belt for transmitting a driving force for reciprocating the carriage 2. Also, 15, 16, and 17, 1
Reference numeral 8 denotes a pair of conveying rollers arranged before and after the recording position of the recording head to perform nipping and conveying of the recording medium, and P denotes a recording medium such as paper, and a platen (P) which regulates the recording surface of the recording medium P flat. (Not shown). At this time, the recording head 23 of the ink jet cartridge C mounted on the carriage 2 protrudes downward from the carriage 2 and is located between the recording medium transport rollers 16 and 18, and the discharge port array of the recording head unit is a platen (non- (Shown) in parallel with the recording material P pressed against the guide surface. The drive belt 52 is driven by the main scanning motor 29, and the transport roller pairs 15 to 18 are driven by the sub-scanning motor 26 (not shown).

In the ink jet recording apparatus of this embodiment,
The recovery unit is arranged on the home position side on the left side of FIG. In the recovery unit, reference numeral 300 denotes a cap unit provided corresponding to each of the plurality of ink jet cartridges C having the recording head 23. The cap unit 300 is slidable in the horizontal direction in FIG. It can be moved up and down. When the carriage 2 is at the home position, the carriage 2 is joined to the recording head 23 and capped,
This prevents the ink in the ejection openings of the recording head 23 from evaporating and thickening / fixing, thereby preventing ejection failure.

In the recovery system unit, reference numeral 500 denotes a pump unit which communicates with the cap unit 300. In the event that the recording head 23 fails to discharge, suction is performed by joining the cap unit 300 and the recording head 23. It is used to generate a negative pressure during recovery processing. Further, in the recovery system unit, reference numeral 401 denotes a blade as a wiping member formed of an elastic member such as rubber, and 402 denotes a blade holder for holding the blade 401.

Here, four ink-jet cartridges mounted on the carriage 2 include black ink (hereinafter abbreviated as K) at C1, cyan ink (hereinafter abbreviated as C) at C2, and magenta ink (hereinafter abbreviated as M) at C3. , C4, yellow ink (hereinafter abbreviated as Y) is used, and the inks are superposed in this order. A color intermediate color can be realized by appropriately overlapping ink dots of C, M, and Y. That is, red can be realized by overlapping M and Y, blue can be realized by overlapping C and M, and green can be realized by overlapping C and Y.
Black can be realized by superimposing three colors of C, M, and Y. However, since black color development is poor and it is difficult to superimpose with high accuracy, chromatic color fringing occurs and ink per unit time. Implantation density becomes too high. Therefore,
Only black is separately ejected (using black ink).

FIG. 2 is a control block diagram of an ink jet recording apparatus for performing thinned multi-pass printing to which the present invention can be applied. In the figure, reference numeral 23 denotes a recording head, which has a plurality of ink discharge ports and a plurality of electrothermal transducers provided corresponding to the ink discharge ports. The recording head 23 is supplied with an ejection signal corresponding to the recording data to the electrothermal transducer, and causes a change in state of the ink due to bubbles generated thereby, thereby ejecting ink droplets from the ejection openings. Reference numeral 29 denotes a main scanning motor that drives the drive belt 52. Reference numeral 20 denotes a print mode switching unit that switches the print mode by a manual switch operation by a user or automatically. Reference numeral 21 denotes an input image signal (hereinafter, a print signal and a print signal) when the thinning multi-pass printing is selected by the print mode switching unit 20. 1) shows a thinned-out print signal creating unit for creating a thinned-out print signal for performing thinned-out multi-pass printing from S. Reference numeral 22 denotes a head driving unit that drives the recording head 23 in accordance with a signal from the thinning-out printing signal generation unit 21, and changes the driving conditions of the recording head 23 according to the printing mode, as described later. Reference numeral 27 denotes a main scanning motor drive signal generating unit for generating a signal for driving the main scanning motor 29. When the thinning multi-pass printing is selected by the print mode switching unit 20, drive signals for the number of passes are sequentially generated. I do. Reference numeral 28 denotes a main scanning motor 29 based on a signal from the main scanning motor driving signal generation unit 27.
2 shows a main scanning motor driving unit for controlling the driving of the main scanning motor. 2
Reference numeral 4 denotes a sub-scanning motor drive signal generation unit for generating a signal for driving the sub-scanning motor 26, and a print mode switching unit 2
When the thinning multi-pass printing is selected by 0, a drive signal for controlling the paper feed amount is generated according to the selected mode. Reference numeral 25 denotes a sub-scanning motor driving unit that controls the driving of the sub-scanning motor 26 based on a signal from the sub-scanning motor driving signal generating unit 24.

In such an ink jet recording apparatus, thinning-out multi-pass printing is performed as follows. When the print mode switching unit 20 selects the thinning multi-pass printing by the manual switch operation by the user or automatically, the input image signal is thinned by the thinning print signal creating unit 21 as shown in FIG. In accordance with the pattern (FIG. 3 (B)),
As shown in (C) and (D), it is divided into a thinned print signal S1 and a thinned print signal S2. Among them, first, the thinned print signal S1 is sent to the head drive unit 22 and the recording head 23
Is driven, and ink droplets are ejected from the ejection openings of the recording head 23. In synchronization with this, the main scanning motor drive signal generation unit 27 (actually, ahead of the head drive by a predetermined time).
The main scanning drive signal of the carriage is generated by the
, The main scanning motor 29 is driven. The carriage 2 moves along the scanning rail 11 to perform the first pass printing. After the printing is completed, the main scanning motor 29 is driven in the reverse direction, and the carriage 2 returns to the start position. Further, after a lapse of a predetermined time, the thinned print signal S2 remaining by the thinning is sent to the head driving unit 22 and the recording head 23
Is driven to perform the second pass printing in the same manner as the first pass, and then prepare for the printing of the next line.

During this time, a sub-scanning roller (not shown) is controlled so that the recording medium does not move, so that thinning two-pass printing is realized. In the above description, the case of thinning two-pass printing has been described, but the same applies to multi-pass printing of three or more times.

Next, the temperature control of the recording head will be described. The temperature control of the print head is performed to maintain the print head at a temperature suitable for a predetermined ink discharge amount by using a heater for heating provided separately from the heater for discharge. It is carried out in the state.

Here, in this embodiment, a so-called closed-loop control is performed by providing a temperature sensor in the recording head. However, a so-called open-loop control is performed by providing a temperature sensor in the apparatus main body to estimate and control the temperature of the recording head. Is also good.

In this embodiment, as shown in FIG. 4, the target temperature setting is changed within the temperature range in which the ink can be stably ejected in order to change the ink ejection amount in accordance with the recording mode described later. ing. FIG. 5 is a simplified flowchart for setting the head temperature adjustment temperature according to the print mode. When a recording start command is input, the recording mode is determined based on the operation of the panel of the recording apparatus main body or the print mode setting data in the recording signal, and each recording is performed at a temperature which is set optimally in advance according to each recording mode. Set the temperature control temperature of the head. In FIG. 4, S, C, and RC described in the columns of the first to fourth scans of each color according to the print mode are recording patterns, and FIG. 6 shows the respective patterns. In FIG. 6, S is a recording pattern used in a normal recording mode, and all recording data in a recording area is recorded without thinning. C selects and records half of the recording data of the recording area in a staggered grid pattern, and RC selects and records the rest of C in an inverted staggered grid pattern.

FIG. 7 shows an example of the ejection amount obtained according to the head temperature adjustment temperature setting. About 34pl at 32 ° C, 40 ° C
Is about 42 pl, and there is a substantially proportional relationship in this temperature range.

FIG. 8 shows the recording densities of B paper (coated paper), which is slightly bleeding but absorbs ink relatively quickly and has a high density, and A paper (PPC paper), which has a low ink fixing property and a low density. 6 shows an example of the relationship between the recording mode and the ejection amount of the recording head for each print mode. In this embodiment, the printing mode can be selected by the user on the operation panel of the printing apparatus in accordance with the image and the printing medium. For paper paper such as paper B, which is inferior to that, 2PASS
4PASS mode is recommended for PPC paper such as A paper and OHP paper.

First, considering printing on paper B, when printing an image with a high image ratio and easy to see, 2PA
Print in SS mode. At this time, as shown in FIG. 8, when the head temperature is set to 36 ° C., an ejection amount of about 38 pl is obtained, and the solid density is about 0 at 2 PASS (point b) compared to 1 PASS (point a). The density is reduced by about 0.04. Therefore, in 2PASS, discharge is performed at 40 ° C. which is 4 ° C. higher than the head temperature control temperature (36 ° C.) in 1PASS, and a discharge amount of about 42 pl larger than the discharge amount in 1PASS (about 38 pl) is obtained. Like that. As is clear from FIG. 8, if the ejection amount is increased even at 2 PASS (point c), a recording density comparable to 1 PASS can be obtained.
In other words, for the same print data, it is possible to prevent the density from lowering by increasing the total ink amount on the print medium at 2 PASS than at 1 PASS. That is, the print mode is set to 2PA even for coated paper having poor recording characteristics.
If the control is made to be SS and the discharge amount of the recording head is controlled to be high, a good image with high density without blurring can be obtained.

Next, considering printing on a recording medium such as paper A, it is necessary to divide the recording data and record it sequentially because it is easy to bleed. However, the density is much larger than that of paper B or the like. To the same recording data,
It is also necessary to print 00% data. However, C, M, C, M,
It is difficult to increase the ejection amount of the Y color ink. Therefore, in this embodiment, only Bk is made to overlap. Here, in order to print 200% of the data, the data is recorded in four times of 50% in order to avoid bleeding (4PAS).
S) It is necessary to set the head temperature of Bk to 3
The discharge rate is slightly lowered (about 34 pl) by lowering to 2 ° C.
Therefore, the density of C, M, Y, and the mixed color portion thereof is lower than that of the B paper (point d), and the density of Bk is also slightly lower (point e).
Has become. However, the bleeding is almost good, and even a paper having poor ink jet recording characteristics can obtain a better image than before.

(Embodiment 2) In this embodiment, the applicant of the present invention applied for controlling the ejection amount of the recording head by Japanese Patent Application No. 3-4742.
An example using a method of modulating the first pulse of the W pulse driving proposed earlier in the specification will be described.

This method is particularly effective in the following cases. When the recording frequency of the head drive is increased in order to increase the recording speed, in the above-described ink jet recording method using the thermal energy of the recording element, the characteristics related to the recording characteristics such as the ejection characteristics change due to self-heating during recording. In some cases, it will. Therefore, by performing PWM control as shown in FIG. 9, the ejection amount is stabilized in accordance with the temperature change of the head. That is, by modulating the pulse width of the pre-heat pulse P1 according to the temperature change of the head, it is possible to stabilize the ejection amount by the main heat pulse P3. In such PWM control, since the control response of the ejection amount is faster than that of the head temperature control used in the first embodiment, control within one scan as well as control within one scan is possible. By performing such drive scanning, a stable ejection amount can be obtained regardless of the frequency and the printing duty.

In the figure, Vop is electric energy necessary for generating heat energy on H.B (heater board), and depends on the area of H.B, resistance value, film structure and nozzle structure of the head. Decided. P1 indicates a preheat pulse width, P2 indicates an interval time, and P3 indicates a main heat pulse width. T1, T2, and T3 are the times from the rise of the preheat pulse, and each is P
The time for determining 1, P2 and P3 is shown. In the divided pulse width modulation driving method, pulses are applied in the order of P1, P2, and P3. P1 is a pulse width for mainly controlling the ink temperature in the nozzle by a preheat pulse, and the pulse width of P1 is controlled by temperature detection using a temperature sensor of the head. At this time, pre-foaming phenomenon is prevented from occurring by applying too much heat energy to H and B. P2 has an interval time to provide a predetermined time interval so that the preheat pulse P1 and the main heat pulse P2 do not interfere with each other, and to function to uniform the temperature distribution of the ink in the nozzles. P3 is a main heat pulse, which causes a bubbling phenomenon to occur on H / B to eject ink droplets from the nozzle holes. These pulse widths are determined by the area of H and B, the resistance value, the film structure, the nozzle structure of the head, and the physical properties of the ink.

FIG. 10 shows two types of pulse width tables corresponding to the head temperature. As shown in FIG.
By changing the contents of the table between, it is possible to change the discharge amount target value between the two types of V ₁ and V ₂ .
In the ejection amount control in this embodiment, a reference ejection amount is secured by the above-described head temperature control (36 ° C.), and is stabilized by the PWM control.

Therefore, in this embodiment, according to the flowchart shown in FIG. 12, even if the thinning multi-pass printing is set, if there is no data of a color other than Bk, the problem of bleeding hardly occurs. Do, C,
Only when there is M and Y data, thinning multi-pass printing by 2PASS is performed. As shown in FIG. 5, the density of Bk changes between a row having C, M, and Y data and a row having no C, M, and Y data. In this embodiment, as shown in FIG. By changing the PWM table accordingly, the ejection amount is changed to stabilize the density. That is, in the present embodiment, even if 2PASS is specified in order to use paper having poor ink absorption characteristics, it is possible to increase the recording speed for an image in which substantially no bleeding problem occurs.

(Embodiment 3) In this embodiment, unlike the above-described embodiment in which the main purpose of multi-pass printing is to improve bleeding and density, the inside of the print head which is likely to be generated by a multi-nozzle print head is described. An example of a recording mode in which high-quality recording is performed without making the density unevenness inconspicuous. The printing method unique to the present embodiment is shown in FIGS. 13 and 14, and for simplification, an example of single-color printing using one recording head will be described.

In FIG. 13, the recording head of eight nozzles is divided into two groups of four nozzles, and paper is fed (half a line) by four nozzles for printing. The method of dividing the print data may be the pattern shown in the first embodiment, but here, in correspondence with the matrix drive method of simultaneously driving the adjacent nozzle groups, the maximum drive frequency of the head is set substantially at the time of divided print. And increasing the scanning speed of the carriage (1/1 /
(Twice if double-thinning). In order to facilitate printing, the pattern was thinned alternately in rows. Of course, even in the pattern of the first embodiment, the carriage speed can be increased by matrix driving every other nozzle.

In the printing method of the present embodiment, the upper half of the printing area of the first line is thinned out by the second nozzle group, and then the half line paper is fed, and then the remaining part of the upper half of the printing area is printed. Is printed by the first nozzle group, and the lower half of the recording area is thinned out. Next, half-line feeding is performed again, and then thinning printing is performed on the remaining lower half of the first line and the upper half of the second line. This operation is repeated, and the remaining portion of the lower half recording area of the last row is recorded by the first nozzle group, thereby completing the recording of all data. When printing is performed by such a printing method, as shown in FIG. 14, recording by different nozzles is performed alternately in the scanning direction of the carriage, so that unevenness of the nozzles becomes less conspicuous and a good image is obtained.

However, according to experiments by the present inventors, even in the printing method of the present embodiment, the density may be lower than that in the simple 1PASS recording, and therefore, in the present embodiment,
When this recording mode is selected, the ejection amount control means is set so as to increase the ejection amount. The discharge amount control means may perform the same temperature control as in the first embodiment.
May be used.

The present invention particularly provides an excellent effect in a recording head and a recording apparatus of a type utilizing thermal energy among ink jet recording types.

The typical configuration and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method can be applied to both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, liquid (ink)
By applying at least one drive signal corresponding to the recorded information and providing a rapid temperature rise exceeding nucleate boiling to an electrothermal transducer arranged corresponding to the sheet or liquid path in which , Heat energy is generated in the electrothermal transducer, and the film is boiled on the heat-acting surface of the recording head.
As a result, air bubbles in the liquid (ink) can be formed in one-to-one correspondence with the drive signal, which is effective. The growth of this bubble,
The liquid (ink) is discharged through the discharge opening by contraction to form at least one droplet. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable. The driving signal in the form of a pulse is disclosed in U.S. Pat.
Suitable are those described in 345262. If the conditions described in U.S. Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface described above are adopted, more excellent recording can be performed.

[0035]

As described above, the number of print head scans for the same print area is controlled, and the print data is divided and the print data is sequentially printed. A print mode control unit for switching between a one-pass print mode for printing and an ejection amount control unit for controlling an ink ejection amount, wherein the total ink amount of the print area in the thinned-out multi-pass print mode is set in the one-pass print mode. By controlling the ejection amount control means so as to be larger than the total ink amount of, the decrease in density in the thinning-out multi-pass printing mode can be reduced so that good image recording can be performed on various recording media. It has become possible.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of an ink jet recording apparatus to which the present invention can be applied.

FIG. 2 is a block diagram of an inkjet recording apparatus to which the present invention can be applied.

FIG. 3 is a diagram for explaining a method of creating a thinned print signal.

FIG. 4 is a table showing print control and head temperature adjustment temperatures according to the first embodiment.

FIG. 5 is a flowchart of setting a temperature control temperature of a print head.

FIG. 6 is an explanatory diagram of a recording pattern according to the first embodiment.

FIG. 7 is a diagram illustrating a correlation between a head temperature control temperature of a recording head and a discharge amount.

FIG. 8 is a diagram illustrating a correlation between an ejection amount and a print density according to a print mode and a print medium.

FIG. 9 is a diagram illustrating a state of setting an ejection amount by PWM control according to the second embodiment.

FIG. 10 is a diagram illustrating a PWM table according to the second embodiment.

FIG. 11 is a diagram showing discharge amount control for table conversion.

FIG. 12 is a flowchart of head drive control according to the second embodiment.

FIG. 13 is an explanatory diagram of a recording process of a recording method according to a third embodiment.

FIG. 14 is an explanatory diagram of a recording method according to a third embodiment when recording is completed.

[Explanation of symbols]

 2 Carriage 20 Print mode switching section 21 Thinning print signal creation section 22 Head drive section 23 Recording head 26 Sub scanning motor 29 Main scanning motor C Cartridge P Recording medium

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Miyuki Matsubara 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Shigetasu Nagoshi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Non-corporation (72) Inventor Yuji Akiyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-1-281944 (JP, A) JP-A-3-146351 ( JP, A) (58) Fields surveyed (Int. Cl. ⁷ , DB name) B41J 2/21 B41J 2/01 B41J 2/05

Claims (5)

(57) [Claims] 1. An ink jet printing apparatus which performs printing using a print head which discharges ink from a plurality of discharge ports, wherein print data divided by a plurality of relative scans of the print head for the same print area is provided. Print control means for performing printing by switching between a thinning multi-pass print mode for sequentially printing and a one-pass print mode for printing all print data in one relative scan of the print head; Discharge amount control means for controlling the amount of ink discharged so that the total amount of ink in the recording area in the thinned-out multi-pass print mode is larger than the total amount of ink in the one-pass print mode. Characteristic inkjet recording device. 2. An ink jet recording apparatus according to claim 1, wherein said discharge amount control means controls the temperature of said recording head to a temperature corresponding to each of said modes. 3. An ink jet recording apparatus according to claim 1, wherein said discharge amount control means controls a driving signal of said recording head in accordance with each of said modes. 4. The print control unit according to claim 1, wherein the same print area is printed by different discharge ports of the print head in the thinned-out multi-pass print mode.
The inkjet recording apparatus according to any one of the preceding claims. 5. The ink jet recording apparatus according to claim 1, wherein the recording head has at least an electrothermal transducer for discharging ink.