JPH07101062A - Ink jet recording apparatus and method - Google Patents

Abstract

PURPOSE:To obtain an ink jet recording apparatus enabling printing free from irregularity and imparting a good image grade by controlling the local ink impact position in reciprocating printing interpolating pixel regions mutually corresponding to the temp. of a recording head or environmental temp. CONSTITUTION:Since an ink impact position is shifted from an ideal printing area by the temp. rise of a recording head when the temp. of the head rises, a blank part is conspicuous and an image grade is deteriorated. Then, the delay time of emitting timing at the time of backward scanning is changed at the head of line printing at the timing of forward scanning in reciprocating printing. That is, the time parameter (delay time) of delay control is set corresponding to the temp. of the recording head just before line printing. Since temp. is controlled by a sub-heater when the temp. of the recording reference temp. is set to 25 deg.C. Concretely, the emitting timing of the head at the time of forward scanning is delayed as the temp. of the head becomes high. As a result, printing forming an image inconspicuous in blank part and free from irregularity can be obtained.

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 for ejecting ink droplets onto a recording medium for recording by using a recording head having a plurality of ejection openings, and a recording method therefor.

[0002]

2. Description of the Related Art In recent years, office automation equipment such as computers, word processors and copying machines have become widespread, and many recording methods for these recording devices have been developed. The ink jet recording apparatus has an excellent feature that it is easy to realize high definition, high speed, excellent quietness, and low cost as compared with other recording methods. In addition, there is a growing need for colorization, and many color inkjet recording devices have been developed. In this ink jet recording apparatus, ink is ejected from nozzles to adhere the ink to recording paper to form an image, but in order to improve the recording speed, a recording head (in which a plurality of recording elements are arranged in an array) is arranged. In the following, as a multihead, a plurality of ink ejection ports and liquid paths are integrated, and a plurality of multiheads are generally provided for color.

FIG. 32 shows the construction of the printer section when printing on the paper surface by the multi-head. In this figure, reference numeral 701 is an ink cartridge. These are composed of an ink tank filled with four color inks, black, cyan, magenta, and yellow, and a multi-head 702. FIG. 33 shows the state of the multi-nozzles arranged on the multi-head from the z direction, and 801 is the multi-head 70.
2 is a multi-nozzle arrayed on top. It returns to FIG. 32 again. Reference numeral 703 denotes a paper feed roller that rotates together with the auxiliary roller 704 in the direction of the arrow while suppressing the print paper P, and feeds the print paper P in the y direction at any time. Reference numeral 705 denotes a paper feed roller, which feeds the print paper P and, at the same time, the roller 70
Similar to Nos. 3 and 704, this is a carriage that moves these together with printing. This is to stand by at the home position (h) at the position shown by the dotted line in the figure when printing is not performed, or when multi-head recovery work is performed.

Before the start of printing, the carriage 706 at the position shown in the figure (home position) moves in the x direction when a print start command arrives and moves n on the multi-head 702.
Printing with the width L is performed on the paper surface by the multi-nozzles 801. When the printing of the data is completed up to the end of the paper, the carriage returns to the original home position and printing is performed again in the x direction. From the end of the first printing to the start of the second printing, the paper feed roller 703 rotates in the arrow direction to feed the paper in the y direction by the width L. In this manner, the printing of only the multi-head width L and the paper feeding are repeated for each scan of the carriage 706, whereby the data printing on one paper surface is completed.

However, unlike a monochrome printer that prints only characters, various elements such as color developability, gradation, and uniformity are required to print an image. Especially regarding uniformity, a slight variation in nozzle unit that occurs in the multi-head manufacturing process affects the ink ejection amount and the direction of the ejection direction of each nozzle when printing, and finally the printed image This causes the image quality to deteriorate as uneven density.

A specific example of the density unevenness will be described with reference to FIGS. Figure 3
In 4-a, reference numeral 91 is a multi-head, which is similar to that of FIG. 33, but now it is assumed that it is composed of eight multi-nozzles 92 for simplicity.

Reference numeral 93 is an ink droplet ejected by the multi-nozzle 92. Normally, it is ideal that ink is ejected in a uniform direction with a uniform discharge amount as shown in this figure. If such a discharge is performed, the discharge of FIG.
As shown in -b, dots of uniform size are landed on the paper surface, and a uniform image without density unevenness is obtained as a whole (Fig. 34-c). However, in reality, as described above, each nozzle has variations, and if printing is performed as it is,
As shown in FIG. 35-a, the sizes and directions of the ink drops ejected from the respective nozzles vary, and the ink drops land on the paper surface as shown in FIG. 35-b. According to this figure, in the main scanning direction of the head, there are periodically blank areas that cannot satisfy the area factor of 100%, and conversely dots are overlapped more than necessary, or they are seen in the center of this figure. Such white streaks are occurring.

The collection of dots landed in such a state has the density distribution shown in FIG. 35-c in the nozzle alignment direction, and as a result, these phenomena are usually seen by the human eye. Is detected as uneven density. In addition, streaks due to variations in the paper feed amount may be noticeable.

Therefore, as a countermeasure against the density unevenness and the connection stripes, the following method for a monochrome ink jet recording apparatus has been devised in Japanese Laid-Open Patent Publication No. 60-107975. The method will be briefly described with reference to FIGS. 36 and 37. According to this method, the multi-head 91 is scanned three times to complete the print area shown in FIGS. 34 and 35, but the area of a half 4-pixel unit is completed in two passes. In this case, the 8 nozzles of the multi-head are divided into a group of 4 upper nozzles and 4 lower nozzles, and the dots printed by one nozzle in one scan are specified image data according to a predetermined image data array. It is thinned out to about half. Then, at the time of the second scan, dots are embedded in the remaining half of the image data to complete the printing of the 4-pixel unit area. The recording method as described above is hereinafter referred to as a divided recording method.

When such a recording method is used, even if the same head as the multi-head shown in FIG. 35 is used, the effect on the print image peculiar to each nozzle is halved, so the printed image is shown in FIG. -B, and black streaks and white streaks as seen in FIG. 35-b become less noticeable. Therefore, the density unevenness is also shown in FIG.
As shown in 6-c, it is considerably relaxed as compared with the case of FIG.

When performing such recording, the first scan and the second scan
At the scan, the image data is divided according to a certain arrangement so as to fill each other. Normally, the image data arrangement (thinning pattern) is arranged in a staggered pattern for each vertical and horizontal pixel as shown in FIG. The most common one is. Therefore, the unit print area (here, 4
In pixel units, printing is completed by the first scan that prints a houndstooth check and the second scan that prints an inverse houndstooth check. 37 (a), (b),
(C) shows how the recording of a certain area is completed when using the zigzag and reverse zigzag patterns, respectively, as in FIGS. 34 to 36, using a multi-head having 8 nozzles. It is the one explained. First, in the first scan, the staggered pattern is recorded using the lower 4 nozzles (Fig. 37-a). Next, in the second scan, the paper is fed by 4 pixels (1/2 of the head length) to record an inverted zigzag pattern (FIG. 35-b). In the third scan, 4 again
The paper is fed by the number of pixels (1/2 of the head length), and the staggered pattern is recorded again (FIG. 37-c). In this manner, the paper feed in units of 4 pixels and the recording of the staggered pattern and the reverse zigzag pattern are alternately performed in order to complete the recording area in units of 4 pixels for each scan. As described above, by completing printing with two different types of nozzles in the same area, it is possible to obtain a high-quality image without density unevenness.

Further, as another technical problem of the ink jet recording apparatus, there is a defect in the shape of dots formed by the deposited ink in relation to the absorption characteristics and evaporation characteristics of the ink on the recording paper, and inadvertent dot connection. In a color inkjet recording apparatus in which inks of a plurality of colors are overlapped and adjacent to each other and sequentially landed, deterioration of image quality due to inadvertent ink bleeding and color mixing is described.
The above-described conventional printing method has an improvement effect in that respect, since the amount of ink in one printing scan is reduced. Further, there is also a so-called multi-pass printing method which does not perform a special paper feed control like the above-mentioned conventional printing method and simply divides into a plurality of printing scans for the same image area and thins out or prints sequentially in color. , Has been proposed as a countermeasure for the above.

[0013]

By the way, in the above-mentioned ink jet recording apparatus, it is important to achieve high image quality and high speed, and in order to achieve high speed, the speed of scanning the recording head is increased. Further, in the case of further increasing the speed, there is also one in which the scanning direction of the recording head can be printed in both directions.

However, if the scan speed of the recording head is increased in this way, the landing position of the ejected ink droplets tends to shift, and the landing position when fine printing by the multi-pass (divided recording method) as described above is performed. If the deviation occurs, there is a problem in that a blank portion where ink droplets cannot be hit is conspicuous and the printing quality deteriorates.

It has been clarified by experiments by the present inventor that such a deviation of the landing position of the ink droplet on the recording paper becomes remarkable when the ejection speed of the ink droplet changes due to the change of the head temperature.

That is, the case where the zigzag and reverse zigzag printing is performed as described above will be explained.
Using a multi-nozzle head having nozzles, zigzag printing is performed in the forward direction and reverse zigzag printing in the backward direction. In this case, printing is performed ideally without deviation of the landing position as shown in FIG. 21-a. However, if the landing position shifts for some reason as shown in FIG. 21-b, a blank portion where ink is not ejected becomes conspicuous. It should be noted that here, the case where printing is performed in zigzag and reverse zigzag is described, but even when other divided printing is performed, a blank portion may be conspicuous and the image quality may be deteriorated.

With respect to such a problem of landing position deviation,
The image quality is improved by correcting the landing position deviation to such an extent that it does not cause a problem in the initial stage of using the recording apparatus.

However, if the environmental temperature changes, or the temperature rises due to printing by the recording head, the ejection speed of the ink droplets ejected from the recording head changes, and the landing position deviates.

FIG. 20 shows how the landing position gradually shifts due to the self-heating of the recording head.

The one-dot chain line shown as the ideal landing position shows the position where the ink is landed on the recording paper without any misalignment at the leading portion during reciprocal printing. On the other hand, what is indicated by a circle is the position where the ball has actually landed.

In the figure, the ejection speed is gradually increased by gradually increasing the temperature of the recording head, and the landing position at the beginning of the line is gradually separated from the ideal printing range. Shows.

On the contrary, when the environmental temperature is low, the landing position shifts to the inside of the ideal landing position.

The present invention has been made in order to solve the above problems, and an object of the present invention is to provide an ink jet recording apparatus and a recording method therefor capable of printing with good image quality without unevenness.

[0024]

In an ink jet recording apparatus and a recording method of the present invention, an ink jet recording in which a recording head performs reciprocal scanning relative to a recording medium and prints the same pixel region in plural times. In the apparatus and the recording method, a local ink landing position in reciprocal printing in which pixel areas are mutually interpolated is controlled by the temperature of the recording head and / or the environmental temperature.

[0025]

According to the present invention, when the print head scans the print medium in a reciprocating manner relative to each other and prints the same pixel area divided into a plurality of times, the print head is locally interpolated in the reciprocating print operation. The recording head temperature and / or
Alternatively, by controlling according to the environmental temperature, the printing speed can be increased and good printing quality without unevenness can be obtained.

[0026]

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

(Embodiment 1) FIG. 1 is a perspective view showing the configuration of a suitable ink jet recording apparatus IJRA to which the present invention is applied or applied. In the figure, reference numeral 5001 is an ink tank (IT), and 5012 is a recording head (IJH) coupled thereto. This ink tank 50
01 and the recording head 5012 form an integrated replaceable cartridge (IJC). Reference numeral 5014 is a carriage (HC) for attaching the cartridge (IJC) to the printer body, and reference numeral 5003 is a guide for scanning the carriage in the sub-scanning direction. Further, a temperature sensor for detecting the temperature inside the recording head 5012 is provided.

Numeral 5000 is a platen roller for scanning the object to be printed indicated by P in the main scanning direction. Reference numeral 5024 is a temperature sensor for measuring the environmental temperature in the apparatus. The carriage 5014 has a recording head 501.
A flexible cable (not shown) for supplying a signal pulse current for driving and a current for head temperature adjustment to 2
Is connected to a printed board (not shown) equipped with an electric circuit (such as the temperature sensor 5012) for controlling the printer.

FIG. 2 shows a replaceable cartridge, 5
Reference numeral 029 is a nozzle portion for ejecting ink droplets. Further, the ink jet recording apparatus IJRA having the above structure will be described in detail. In the recording device IJRA, the driving force transmission gear 5 is interlocked with the forward / reverse rotation of the drive motor 5013.
Lead screw 5 rotating through 011 and 5009
Carriage H engaging with the spiral groove 5004 of 005
C has a pin (not shown) and is reciprocated in the directions of arrows a and b. A paper pressing plate 5002 presses the paper against the platen 5000 in the carriage movement direction.
Reference numerals 5007 and 5008 denote photocouplers for confirming the presence of the lever 5006 of the carriage HC in this area, and checking the motor 50.
13 is a home position detecting means for switching the rotation direction of the shaft 13 and the like. Reference numeral 5016 denotes a member that supports a cap member 5022 that caps the front surface of the recording head.
Is a suction means for sucking the inside of the cap, and performs suction recovery of the recording head 5012 through the opening 5023 in the cap.

5017 is a cleaning blade,
Reference numeral 19 denotes a member that allows the blade 5017 to move in the front-rear direction, and these members are supported by the main body support plate 5018. Needless to say, a well-known cleaning blade can be applied to this example instead of this form.
Reference numeral 5021 denotes a lever for starting suction for suction recovery, which moves in accordance with the movement of the cam 5020 that engages with the carriage HC, and the driving force from the drive motor is controlled by known transmission means such as clutch switching. To be done.

The capping, cleaning, and suction recovery are configured so that the desired processing can be performed at their corresponding positions by the action of the lead screw 5005 when the carriage HC reaches the home position side area. Any desired operation can be applied to the present example if the desired operation is performed at the timing.

FIG. 3 shows the details of the recording head 5012, and a heater board 5100 formed by a semiconductor manufacturing process is provided on the upper surface of the support 5300. The heater board 5100 is provided with a temperature adjusting heater (heating heater) 5110 formed in the same semiconductor manufacturing process for keeping the recording head 5012 warm and adjusting the temperature. Reference numeral 5200 denotes a wiring board arranged on the support 5300, and the wiring board 5200 and the temperature adjustment heater 5100 and the discharge (main) heater 5113 are wired by wire bonding or the like (wiring is not shown). ). In addition, the temperature adjustment heater 5110 is the support 5
A heater member formed by a process other than the heater board 5100 such as 300 may be attached.

Reference numeral 5114 is a bubble generated by being heated by the discharge heater 5113. Reference numeral 5115 indicates the ejected ink droplet. Reference numeral 5112 is a common liquid chamber for the ejection ink to flow into the recording head.

Next, the first embodiment in which the present invention is applied to the above-mentioned recording apparatus will be concretely described. FIG. 15 is a flowchart showing the operation of the first embodiment.

As described above, the multi-pass printing method is performed, but here, printing is performed in two passes. That is, the printing method as shown in FIGS. Further, for high speed printing, printing is performed in a reciprocating manner. The timing of this printing is set using an encoder for detecting the position of the carriage.

Speaking of the ink landing position, even if the ink is initially corrected and correctly aligned, if nothing is controlled, printing is continuously performed, and if the head temperature gradually rises,
As shown in FIG. 20, since the landing position deviates from the ideal printing range due to the temperature rise of the recording head and the like, the blank portion becomes conspicuous and the image quality deteriorates as shown in FIG. 21-b.

Therefore, in this embodiment, the delay time of the ejection timing at the time of the backward scan is changed at the head of the line printing at the time of the backward scan in the reciprocal printing.

Explaining with the flowchart of FIG. 15, the time parameter (delay time) of the delay control is set according to the temperature of the recording head immediately before line printing at this time. When the temperature of the recording head is 25 ° C. or lower, the temperature is adjusted by the sub heater, so the reference temperature is set to 25 ° C. (see the table of head temperature and time parameter). Specifically, as shown in the delay time table, the higher the head temperature, the later the ejection timing at the beginning of the backward scan is delayed.

As a result, the printed matter was as shown in FIG. 22 (or FIG. 28-c), and the blank portion was not conspicuous, and it was possible to obtain the printing without unevenness on the image. Actually, when the head temperature gradually rises during continuous printing, the landing position will be entirely displaced by l in FIG. 22, but this figure is emphasized for explanation. It is a visible one and is hardly noticeable visually. That is, when viewed locally, the state is as shown in FIG. 21-a.

This indicates that it is not always necessary to control the printing so that the printing is performed at the ideal landing position, and more specifically, it is shown that there is no problem on the image if the local ideal divided printing is performed. There is.

In the above embodiment, the value of the diode, which is the temperature sensor on the head, is used as the head temperature, but the estimated calculation value of the head temperature by the main body may be used. Further, in the above embodiment, the delay control is changed at the beginning of the line during the backward scanning, but it may be similarly changed during the forward scanning. Alternatively, it may be carried out in both directions. An example thereof is shown in the flowchart of FIG. Further, instead of the direct value of the head temperature, the base temperature of the head estimated from the change value of the value may be used as a variable.

Here, the printing method is described as 2 passes, but it goes without saying that the same effect can be obtained with other multi passes such as 3 passes and 4 passes.

In the delay time table, the average value of the ejection speed υ at the head temperature is also described. The delay time is set to 0 when the head temperature is 25 ° C, and the discharge speed υ
And the distance between the head and the paper was 1.5 mm. Figure 1
The delay time in 6 becomes smaller and becomes half.

(Second Embodiment) Next, a second embodiment will be described. In the present embodiment, the driving speed is relatively slow and the temperature rise of the recording head is small, and the ejection speed depends almost on the environmental temperature where the recording apparatus is placed. Change the time). The delay time table may use the head temperature of the delay time table as the environmental temperature. Basically, the delay amount at the time of backward scanning is set at the top of the page and is not changed while printing one sheet.

However, when there is a time between printings such as when the page printer is not used, the delay amount is changed according to the environmental temperature at that time even in the middle of the page.

Further, although the delay amount in the backward scanning is used here, it may be performed in the forward scanning or in both the reciprocating directions. The same table as the delay time table is used for both directions.

It is also possible to control the ejection speed and the ejection amount by changing the driving conditions such as the drive pulse width of the head at the same time as the delay amount. In this case, changes in the ejection amount with respect to the ambient temperature are corrected as much as possible. It is possible to do so, which is preferable. The drive pulse at this time is preferably a double pulse waveform described in the next embodiment because the ejection amount and the ejection speed can be easily controlled. As a result of the above control, 15 ° C to 35 ° C
Even if the two-pass reciprocal printing is performed under the environmental conditions as described in Example 1, it is possible to obtain a good image quality without unevenness.

(Embodiment 3) In the embodiment shown in the flowchart of FIG. 18, PWM control of the drive pulse waveform is performed. Actually, the PWM control is a method for controlling the ejection amount and speed of the recording head, in which the present applicant modulates the first pulse of the double pulse drive previously proposed in Japanese Patent Application No. 3-4742 (PW).
M).

This method is particularly effective in the following cases. When the recording frequency (driving frequency) for driving the head is increased in order to increase the recording speed, the inkjet recording method using the thermal energy of the recording element described above is related to recording characteristics such as ejection characteristics due to self-heating during recording. Sometimes things change. Therefore, as shown in FIG. 30, PWM control is performed to stabilize the ejection amount and ejection speed according to 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, the ejection amount and the ejection speed by the main heat pulse P3 can be stabilized.

Unlike the one used in the modification of the second embodiment, such a PWM control can control the discharge speed in a high response in almost real time, so that the control can be performed for each scan as well as within one scan. Can also be controlled. By driving in this way, stable and independent of frequency and print duty,
It is possible to obtain the discharge amount and the discharge speed.

In the figure, Vop is H / B (heater board)
It is electrical energy required to generate thermal energy above, and is determined by the area of H · B, resistance value / film structure and nozzle structure of the head. P1 indicates the preheat pulse width, P2 indicates the interval time, and P3 indicates the main heat pulse width. T1, T2, T3 are the times from the rising of the preheat pulse, P1, P respectively.
2 shows the time for determining P3. The divided pulse width modulation driving method gives pulses in the order of P1, P2 and P3. P1 is a preheat pulse, which is a pulse width mainly for controlling the ink temperature in the nozzle, and the pulse width of P1 is controlled by the temperature detected by the temperature sensor of the head and the temperature estimated by calculation. At this time, excessive heat energy is applied to H and B so that the pre-foaming phenomenon does not occur. P2 is an interval time and is provided with a predetermined time interval so that the pre-heat pulse P1 and the main heat pulse P2 do not interfere with each other, and has the function of equalizing the temperature distribution of the ink in the nozzles. P3 is a main heat pulse that causes a bubbling phenomenon on H and B to eject ink droplets from the nozzle holes. These pulse widths are determined by the area of H · B, the resistance value, the film structure, the nozzle structure of the head, and the physical properties of the ink.

FIG. 31 shows a pulse width table corresponding to the head temperature. As shown in FIG. 4, even if the head temperature changes, it is possible to stably control to a constant target ejection speed of 10 M / S. At this time, if the head temperature is lower than the predetermined temperature, the temperature is controlled by the sub-heater in the head to secure the reference ejection speed.

Therefore, as shown in FIG. 23A, when the high duty printing is performed during one scan, if the PWM control is not performed, the portion printed with the high duty is as shown in FIG.
As shown by 2, 2 ', the head temperature changes abruptly in the line, so the ejection speed changes, and as a result, as shown in FIG.
As shown in 3, the landing position deviation in reciprocal printing is high
Since it occurs at the y-printed part, it appears to be uneven.

However, as described in the present embodiment, by performing the PWM control, as shown in FIG. 23-4, the landing position shift due to the local change in the ejection speed does not occur,
It is possible to obtain a high-quality image without unevenness.

(Embodiment 4) In the embodiment shown in the flow chart of FIG. 19, delay control is performed together with PWM control of the drive pulse waveform.

Since the PWM control as shown in the third embodiment can control the discharge amount and the discharge speed to be constant,
The landing position does not shift when printing back and forth.

By the way, the temperature range of the head in which the above ejection speed can be controlled to be constant (hereinafter referred to as the PWM control range)
Are limited to some extent. For example, in Example 3, the head temperature is up to 49 ° C. Therefore, when printing is performed at a head temperature higher than this, the ink ejection speed cannot be controlled to be constant. For example, when high printing of the print duty is continuously performed, at first, as shown in FIG. 24 or FIG. 28-4, it is OK, but the landing position shift gradually as shown in FIG. 25 or 28-2 with the head temperature. Occurs. Therefore, stopping the printing operation so as not to reach a temperature higher than this is also one means, but this substantially lowers the printing throughput. Therefore, in the present embodiment, the ejection speed with respect to the head temperature is not controlled to be completely constant, but is controlled as shown in FIG. 27, while the environmental temperature, the head temperature and the like are used as in the first and second embodiments. The delay control is performed. That is, by controlling the ejection speed accompanying a rapid temperature change while the head scans and prints one line to a certain degree by PWM control, it is possible to prevent a local landing position deviation from occurring, and By correcting the effect of the ejection speed, which changes due to the effect of gradual temperature changes such as temperature, by delay control, it is possible to prevent local landing position deviations from occurring regardless of the print duty and the environmental temperature. Is.

More specifically, as shown in the flowchart of FIG. 18, first, the delay time is set according to the temperature of the recording head immediately before line printing. Next in FIG.
PWM control is performed as shown in FIG. 6 based on the pulse width table corresponding to the head temperature shown in FIG. By doing this,
(Or FIG. 29-e2), and even if the head becomes extremely hot, the landing deviation is not conspicuous, and it is possible to obtain printing with no unevenness on the image. Further, as shown in the flowchart of FIG. 19, the same effect was obtained even if the delay time was changed depending on the environmental temperature.

By the way, the temperature of the above-mentioned recording head is
A measured value may be used or an estimated calculated value may be used.

Further, although a plurality of recording heads are integrated and each head may carry out delay control separately, all heads may carry out the same delay control at the same time depending on the environmental temperature. Is also good.

The embodiments of the present invention have been described above.
As can be seen from the text, in order to carry out the present invention, it is necessary to correct the registration of the reciprocal printing of the recording device in the initial stage. In this embodiment, the resist correction is performed by changing the delay time of the ink ejection timing. A specific example will be described below.

A concrete description will be given with reference to FIGS. FIG. 11 shows a carriage 70 that scans at a speed S.
The head 901 fixed at 6 has a discharge angle θ and a discharge speed V
11A and 11B show a state in which an ink drop is ejected on a paper surface separated by a distance P, comparing the case of the forward path (FIG. 11-a) and the case of the return path (FIG. 11-b). The carriage speed can be switched to S in the forward path and to -S in the reverse path, but the ejection angle of the head is always fixed in the constant direction θ. At this time, the distance between the position ejected by the head in the scanning direction and the position where ink is actually landed on the paper surface is ΔF on the forward path and ΔB on the return path, and ΔF = P × (Vsinθ + S) / Vcosθ [Delta] B = P * (Vsin [theta] -S) / Vcos [theta], and the ejection timings for the target pixel differ by a distance of ([Delta] F- [Delta] B) = P * 2S / Vcos [theta].

If this value is always constant in any recording device or recording head, the dot positions in both directions can be optimized by constantly driving the head at appropriate ejection timings. However, in reality, the thickness of the recording paper varies P, the speed variation of the carriage varies S, and the variation of the recording head varies the ejection speed V. Also,
Even with the same head, the ejection speed may change depending on the temperature and the scanning direction, or may change gradually as the ejection is repeated.

FIG. 13 shows ΔF and Δ when the sheet interval P, the carriage speed S, the discharge speed V, and the discharge angle θ in FIG. 11 are changed during forward scan and backward scan, respectively.
B, (ΔF−ΔB), and the dot position shift amount are shown.

In the uppermost row of FIG. 13, the sheet interval P = 1.2 m
m, carriage speed S = 4.318 m / sec (reciprocal same speed), ejection speed V = 12.5 / sec (reciprocal same speed), ejection angle θ = 10 ° (reciprocal same angle),
ΔF, ΔB and optimum correction amount (ΔF-
Assuming that the head is driven so that ΔB) = 84.18 μm, the bidirectional dot position deviation amount is set to “0”.

On the other hand, since the values of various factors change little by little in the second and subsequent stages, the appropriate correction amount (ΔF-ΔB) in each case is different. But,
Even at this time, since the head is driven at the same timing as the uppermost stage, a dot position deviation amount in both directions occurs,
At this time, the value of this shift amount is a difference from the uppermost stage of the optimum correction amount (ΔF−ΔB).

In the table of FIG. 13, the individual factor values are normally swung in the range of values that can be changed, but as can be seen, the factor that can most affect the bidirectional dot misalignment is the sheet interval P. . According to this table, a gap of 42.29 μm (half a pixel or more at a pixel density of 360 dpi) occurs if the gap between sheets is changed by ± 0.2 mm with an optimized correction amount of 1.2 mm. Become. The thickness of normal paper itself is stable at about 100 μm, but such a thickness change is within a range that can be easily moved due to variations in the recording apparatus main body and variations in the recording head. It will be necessary to make corrections accordingly.

Such a change between papers can occur not only during the variation of the recording apparatus itself but also during printing. Ideally, the printing portion on the recording paper is kept smooth by the paper holding mechanism before and after printing. However, when the print duty is high, or when the divided recording method is used that completes the printing by dividing the same recording scan into several recording scans, the paper surface after printing absorbs ink Shrinkage is likely to occur, and only the printing portion is likely to float. In this case, the sheet interval P may be different between the forward pass and the return pass for each printing scan, and the optimum correction amount is changed due to the floating of the paper (hereinafter referred to as cockling), which causes the dot position deviation during bidirectional printing. I will let you.

As described above, the correction amount cannot be kept constant due to various factors. Therefore, it was confirmed that it is preferable to optimize these dot positions when performing bidirectional printing or recording with a head of a plurality of colors.

In any case, as described above, when performing bidirectional printing or recording with a head of a plurality of colors, these dot positions are determined from the linearity of the vertical ruled line of the specific pattern and corrected. Therefore, there is a limit to the determination accuracy, and there is also a limit to maintaining a good image. That is, the method of confirming the dot position by the vertical ruled line described so far is difficult to make a fine adjustment for one pixel or less such as a unit of several μm.

Moreover, as the image quality and the speed have been increased as in recent years, a new dot position correction method capable of performing correction in such a small amount unit is required. Further, in the past, when the material and thickness of the recording medium change for the printer, different measures are required, and it is difficult to obtain a good image state, and the recording characteristics are not affected by the material and thickness of the recording medium. It is important to be able to achieve satisfactorily and accurately, and the present invention provides a test printing method and apparatus that can meet this demand.

In any case, there is no conventional method in which the operator can easily and accurately determine the test print image.

Further, according to the present invention, not only the linearity but also the uniformity of the test print image such as the presence / absence of the image and the change of the color tone is adopted as the criterion, so that the precision of the determination can be remarkably improved, and the accuracy of the unit can be increased by several μm. The present invention provides a test printing method and apparatus capable of achieving fine adjustment of 1 pixel or less.

As a more preferable condition for the present invention, as a test pattern, an area pattern having a predetermined area includes two or more adjacent portions of dots printed by forward scanning and dots printed by backward scanning. Under the conditions described above, there is a part where dots printed by the backward scan exist on the right side of the dots printed by the forward scan and a part where dots printed by the backward scan exist on the left side.
This preferable condition is that when a dot shift occurs in reciprocal scanning, both a portion where two dots are overlapped more than necessary and a portion where two dots are separated more than necessary can be present in the area pattern. Therefore, these gradation changes are a unit recognized as a clarification of density unevenness and a texture for visual observation or automatic density determination. In addition, it is preferable that the dots printed by the forward scan and the dots printed by the backward scan are continuous in a plurality of dots because it is easier to determine the change in density (see the embodiment).

To improve the easiness of determining density unevenness and texture is to increase the number of repetitions of the above-mentioned dot adjoining portions, which complicates the thinning pattern or increases the test print area in the scanning direction. It is also possible to increase the length in the direction intersecting the scanning direction to the range where all the recording dots of the recording head are used. Increasing the area occupied by this area pattern not only improves the sensitivity of density unevenness and texture, but also unevenness of scanning of the carriage and unevenness of conveyance of the recording medium (when the test pattern of the present invention is repeated), recording medium. This is preferable because it enables dot position adjustment including various unstable factors such as cockling.

In order to form the divided data of the present invention as a reliable dot image on the recording medium, particularly in the case of the ink jet, the divided data of the above data are four or more different types of divided data. It is preferable that a plurality of types are provided for each of the forward scanning process and the backward scanning process to form the line pattern by a plurality of reciprocating scans. This is because the fixability of the ink droplets can be improved and the accuracy can be improved.

Forming a plurality of the test patterns in which the reciprocal scanning registration timing of the divided data is made different within a range smaller than 1.00 pixel makes it possible to perform the above-mentioned determination more easily and to easily carry out a desired resist adjustment. it can. This reciprocal scanning registration timing is 1.
Having a correction step or correction means that can be changed in a range smaller than 00 pixel ensures that a preferable correction can be achieved. Further, the fact that the execution data of each of the forward scan and the backward scan is divided so as to be at least a plurality of dots continuous in the scanning direction further clarifies the feature of the present invention.

According to the present invention, the test pattern print mode includes a plurality of different same area test patterns, and the test pattern in the test pattern print mode is specified by specifying each of the plurality of same area test patterns. By making it possible to perform adjustment according to the accuracy requirement of the apparatus, for example, high accuracy determination can be made at the time of shipment of the apparatus, and then a normal level determination can be made for subsequent operator's determination. .
The high-accuracy determination may include a first test pattern including a central area of the recording medium and left and right areas of the central area as test print areas. The second test pattern may include a region smaller than the test pattern as a test print region. In this example of high precision determination, the entire state of the recording medium in the width direction can be taken into consideration.
This is a preferred example.

The color test print of the present invention is also possible with the above-mentioned invention, but is characterized by adopting a more developed change in image color as a criterion, and specifically,
In an ink test printing method capable of executing a bidirectional mode in which printing is performed by reciprocal scanning of a multi-color multi-dot head for the same area, the data forming the overlapping test pattern of the multiple colors to be printed for the same area is divided by color. The ink test printing method is characterized in that it has a test pattern print mode for forming an overlapping test pattern of a plurality of colors in the same region by printing the forward scanning process and the backward scanning process to which data is respectively given.

The apparatus invention of the present invention includes a carriage for carrying out reciprocal scanning with a multi-inkjet head mounted thereon, a transport means for transporting a recording medium in a direction intersecting the scanning direction, and a multi-dot head for the same area. In an inkjet recording apparatus provided with a bidirectional mode in which printing is performed by both reciprocating scanning and a memory means for storing a test pattern for displaying a reciprocating resist, the memory means stops the recording medium as the test pattern. A typical example is an inkjet recording apparatus characterized in that it stores data for a forward scanning process and data for a backward scanning process, which are divided data of data forming a test pattern to be printed in the same area in a state. it can.

According to the ink jet recording apparatus of the present invention,
Using a multi-head with multiple ink ejection ports arranged,
In an inkjet recording method that completes recording by performing bidirectional recording scanning and relatively sequential paper feed, the same printing area is divided into forward scanning and backward scanning divided recording (or multi-color multi-head) Such a pattern is completed, and the proper value of the bidirectional recording timing (or the proper value of the recording timing of each color multi-head) is determined and stored based on the goodness of the uniformity of the pattern (or the difference in tint). As a result, it has become possible to perform dot position correction with higher accuracy than ever before and obtain high-quality images.

The invention will be understood more clearly by the following description of the examples.

FIG. 7 shows that a complete strip-shaped area pattern is formed as a test pattern (substantially equivalent to the area patterning of a substantially strip-shaped line pattern).
The upper part shows the thinning pattern of the reciprocal scan divided data,
A pattern in which the ejection drive timing is shifted by 1/4 pixel for bidirectional printing centering on ± 0.00 pixel (± 0.25
Pixel, ± 0.50 pixel).

In the present embodiment, a block of the number of nozzles of the vertical head × 4 pixels in the horizontal direction is printed by 50% so as to have a complementary relationship between the forward printing scan and the backward printing scan to form a 100% solid image. . Further, in this embodiment, a multi-head having 16 pixels in the vertical direction is assumed, and therefore, a pattern of 16 pixels in the vertical direction is shown in FIG. 7, but for a head having more nozzles, for example, The effect of this embodiment can be obtained by partially using continuous nozzles instead of using all nozzles.

In the conventional example, the proper value is determined from the linearity of the vertical ruled line, but in this embodiment, it is determined from the uniformity of the entire image. As can be seen from FIG. 7, when the dot correction is not sufficient, the forward printing and the backward printing are not complemented sufficiently, and a small white streak appears between the blocks. When actually observed, this has a fine texture in the vertical direction, resulting in an image with impaired uniformity.

The process in which the user actually makes the reciprocating register adjustment will be described below with reference to FIG.

First, the user specifies the bidirectional registration adjustment mode by the SW of the main body, and the main body enters the user registration adjustment mode by this. Then, the user is notified that the mode has been entered by using an LED or the like.

The user confirms that the adjustment mode has been entered, and starts registration pattern printing. FIG. 9 shows an arrangement example of the patterns recorded by this. This figure shows a pattern recorded in 15 steps in the paper feed direction while changing the reciprocating dot position by 10 μm, and the user selects the pattern with the most uniformness from this pattern group. Since the pattern is printed at three points on the paper surface for each step, it is possible to determine the slight unevenness of the carriage speed and the floating of the paper, which occur on the left and right of the paper surface, in consideration of the whole.

Four LEDs are provided between the left end and the center pattern.
A model diagram showing the lighting state of is simultaneously printed, which is used when the registration adjustment pattern selected by the user is input to the main body. The user adjusts the LED of the main body to the lighting state of the LED shown next to the most uniform pattern by the input SW. For example, in FIG. 9, if it is determined that the pattern beside XX is the most uniform, the input SW is pressed several times until the LED changes to XX, and this state Push the memory switch until it is complete. As a result, the main body stores the ejection timing in both directions when a uniform 100% image is obtained, and in the subsequent printing, the head is always ejected at the above timing.

After the new correction value has been stored in the ROM or the like, the user register adjustment mode ends and the main body returns to the normal print mode again.

In FIG. 9, the ink ejection timing in both directions is changed over 15 steps every 10 μm, but the pitch and the number of steps are twice or more the distance of each pixel of the print image on the same paper surface. It is desirable to do so. In this embodiment, 360 dpi, that is, 70 between pixels
Since it is assumed that the condition is around μm, it is 2 before and after the center value.
It is possible to obtain the shifted state of the dots over the pixels of 140 μm.

Further, here, -70 μm to +70 μm
Until then, all patterns are always printed at equal intervals of 10 μm. However, by increasing the shift amount at both ends as described below, it is possible to form a state in which uniformity is obviously deteriorated on both sides of all patterns. Is also good.

In FIG. 9, 3 on both sides from ○ ●●● at the center
The pattern is shifted ± 20 μm. After that, the two patterns are shifted ± 30 μm, and the last two patterns are ± 40 μm.
Let's move it one by one. Then, this correction pattern is all 15
Even though it is a pattern, it is possible to control a range of ± 200 μm with respect to the center value. If you do this, all 15
Dot dots in both directions are completely displaced in the pattern, and a state in which uniformity is clearly deteriorated will always occur on both sides, so even if it is difficult to determine the uniformity near the appropriate value, the white stripe The proper value can be easily determined by the distance (the number of steps) from the patterns on both sides where is clearly visible.

In the present embodiment, the print pattern has been described in units of horizontal 4 blocks, but the shape and size of this block are not limited to this. Further, if a block that is long in the lateral direction is used, the period in which white stripes appear becomes longer, and rough texture can be seen. Also, if the print patterns of the forward pass and the backward pass are reversed every several pixels in the vertical direction, short white stripes will appear finely in places. In any case, it is preferable to apply a block unit that creates a texture that clearly shows the difference between good and bad uniformity.

As described above, according to this embodiment,
The pattern for printing in block units so that the forward scan and the backward scan are complementary to each other determines the appropriate value of the print timing from the uniformity, and inputs it to the main body to shift the impact position of bidirectional printing. Can be corrected with high accuracy.

Although the above description has been made on the basis of the case where the user himself / herself performs the correction, if these corrections are performed at the time of shipment of the main body and the correction value here is set as the central value of the user register adjustment pattern, the adjustment range thereafter is set. It can be squeezed in advance. The factors that actually cause these dot shifts are
As described above, since many of them are specific to the recording apparatus main body, it is preferable to make such an absolute correction before loading.

FIG. 12 shows a block diagram of an example of the printing apparatus of the present invention. Reference numeral 1 is a means for designating a test print mode, which functions as an operating mechanism for executing the test print mode in the normal recording mode. In this embodiment, the function of designating a test pattern in the test pattern print mode by designating one of a plurality of different same-area test patterns and the central area of the recording medium It has both a function of being able to select a first test pattern including the left and right regions of the central region as a test print region and a second test pattern including a region smaller than the first test pattern as a test print region. ing. Reference numeral 2 denotes a reciprocal registration correcting unit in the reciprocating scan of the print, which does not function when there is no new correction command, and causes the memory unit 3 which stores a predetermined rewritable print timing including the reciprocating resist in the reciprocating scanning to function. The memory means 3 also uses the stored reciprocating resist in the reciprocating scan as the reciprocating resist in the reciprocal recording scan in the normal recording mode. 8 is a recording medium 1 for correcting the reciprocating resist.
The reciprocal registration correcting means 2 is operated by a print determining means as means for determining the state of the test pattern on 0 (described later, automatic determining means, etc.) or means operated by the operator, and input to the print determining means 8. The correction is executed, and the reciprocating resist of the memory means 3 is rewritten.

On the other hand, 5 is a data memory means for storing the test print data and area data for determining the print area, which has forward scan data 51, backward scan data 52 and other data and area data storage means 6. In the present embodiment, it becomes possible to make adjustments according to the accuracy requirements of the apparatus, and for example, high accuracy determination is performed at the time of shipment of the apparatus, and then a normal level judgment can be performed for the operator's determination thereafter. The first test pattern may include a central print area of the recording medium and the left and right areas of the central print area as test print areas. As a normal level determination, an area smaller than the first test pattern may be used. Is used as a test print area as a second test pattern. Further, although only one data may be stored in the data memory means 5, in the present embodiment, the stored data X
(= Forward scan data X1 + reverse scan data X2), Y and Z are divided into reciprocating scans as shown by the formulas in the figure (the contents described in the above-mentioned embodiments and the outline of the invention are all applicable. Of the divided data, "1" is added to the data for forward scanning, and "2" is added to the data for backward scanning. Particularly, in this embodiment, since the ink jet recording method is adopted, it is preferable that the stored data Z is used normally or fixedly. Stored data Z is 4 different
A plurality of types of divided data (A1, B1, A2, B2) of more than one type are given to each of the forward scan process (A1, B1) and the backward scan process (A2, B2), and a plurality of reciprocating scans are performed. As described above, the test pattern can be printed.

Reference numeral 4 denotes a known carriage reciprocating means, which is provided with a position detecting mechanism such as a motor and an encoder as the reciprocating drive switching means 41. Reference numeral 7 is a known head driving means, and in the present embodiment, is an inkjet type ink jet head driving means proposed by the applicant of the present invention using film boiling, and means 71 for performing reciprocal printing switching at a timing corresponding to the reciprocating resist. It is equipped with. In the test print mode, the head driving means 7 sets the reciprocal scanning registration timing of the divided data to 1.00 p as shown in FIG.
A plurality of the above-mentioned test patterns, which are different in a range smaller than the pixel size, are formed by using a multi-nozzle inkjet head 9 provided with a large number of heating elements for forming bubbles.

With such a device configuration shown in FIG. 12, the above-described embodiments can be executed, and the invention described in the outline of the present invention can be executed. In particular, when the ink jet head has a head structure in which a plurality of color heads have been mutually adjusted in advance as shown in FIG. 32 and then integrated, the registration adjustment of each head portion is performed by an ink test of one of them. The block diagram in this embodiment can be determined by a single color or
It will be understood that it can be used with any of the multiple color integrated heads

[0101]

As described above, according to the present invention,
In an inkjet recording apparatus that performs reciprocal printing and divided recording, by controlling the landing position in accordance with the temperature of the recording head and / or the environmental temperature, it is possible to obtain good print quality without reciprocating positional deviation while maintaining high printing speed. The effect that can be obtained is obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing the configuration of an inkjet recording apparatus according to the present invention.

FIG. 2 is a perspective view showing the cartridge of FIG.

FIG. 3 is a configuration diagram showing details of the recording head of FIG.

FIG. 4 is a characteristic diagram showing a relationship between head temperature and ink ejection speed.

FIG. 5 is a diagram showing a pulse width table corresponding to head temperature.

FIG. 6 is an explanatory diagram showing an example of PWM control.

FIG. 7 is a diagram showing a test pattern of an example.

FIG. 8 is a diagram showing a test pattern of an example.

FIG. 9 is a diagram showing an example of pattern arrangement in the adjustment mode.

FIG. 10 is a process chart when performing reciprocating cash register adjustment.

FIG. 11 is a diagram showing a state in which the head has dropped ink.

FIG. 12 is a block diagram showing a configuration example of a printing apparatus.

FIG. 13 is a diagram showing a dot positional deviation amount.

FIG. 14 is an explanatory diagram showing an example of a thinning pattern.

FIG. 15 is a flowchart showing the operation of the first embodiment.

FIG. 16 is a flowchart showing another operation of the first embodiment.

FIG. 17 is a flowchart showing the operation of the second embodiment.

FIG. 18 is a flowchart showing the operation of the third embodiment.

FIG. 19 is a flowchart showing the operation of the fourth embodiment.

FIG. 20 is an explanatory diagram showing how the ink landing position is displaced.

FIG. 21 is an explanatory diagram showing a state where the landing position of ink is displaced.

FIG. 22 is an explanatory diagram showing the operation of the first embodiment.

FIG. 23 is an explanatory diagram showing the operation of the third embodiment.

FIG. 24 is an explanatory diagram showing the operation of the fourth embodiment.

FIG. 25 is an explanatory diagram showing the operation of the fourth embodiment.

FIG. 26 is an explanatory diagram showing the operation of the fourth embodiment.

FIG. 27 is an explanatory diagram showing the operation of the fourth embodiment.

FIG. 28 is an explanatory diagram showing the operation of each embodiment.

FIG. 29 is an explanatory diagram showing the operation of each example.

FIG. 30 is an explanatory diagram showing an example of PWM control.

FIG. 31 is a diagram showing a pulse width table corresponding to head temperature.

FIG. 32 is a block diagram showing the configuration of a printer unit having a multi-head.

FIG. 33 is a perspective view of the multi-nozzle shown in FIG. 32 viewed from the Z direction.

FIG. 34 is an explanatory diagram showing an example of uneven density.

FIG. 35 is an explanatory diagram showing an example of uneven density.

FIG. 36 is an explanatory diagram showing an example of a monochrome inkjet recording method.

FIG. 37 is an explanatory diagram showing an example of a monochrome inkjet recording method.

[Explanation of symbols]

 5012 recording head

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location B41J 3/04 104 F (72) Inventor Hitoshi Nishikori 3-30-2 Shimomaruko, Ota-ku, Tokyo Kiya Non non corporation

Claims (16)

[Claims] 1. An inkjet recording apparatus in which a recording head scans a recording medium reciprocally relative to each other and prints the same pixel area in a plurality of times. An ink jet recording apparatus characterized in that a specific ink landing position is controlled by a temperature of a recording head and / or an environmental temperature. 2. The ink jet recording apparatus according to claim 1, wherein the timing of ejecting ink is controlled according to the temperature of the recording head and / or the environmental temperature. 3. The ink jet recording apparatus according to claim 1, wherein the drive condition of the recording head is changed according to the temperature and / or the environmental temperature of the recording head. 4. The ink jet recording apparatus according to claim 2, wherein the timing at which the ink is ejected is changed at the head of scanning by the recording head. 5. The ink jet recording apparatus according to claim 3, wherein the driving condition is changed by changing the pulse width. 6. The ink jet recording apparatus according to claim 3, wherein the driving condition is changed by changing the divided pulse. 7. The ink jet recording apparatus according to claim 4, wherein the timing of ejecting ink is changed during forward printing and / or backward printing. 8. The ink jet recording apparatus according to claim 4, wherein the timing of ejecting ink is changed only at the head of the page to be printed. 9. An inkjet recording method in which a recording head scans a recording medium reciprocally relative to each other and prints the same pixel region in a plurality of times, and in a reciprocal printing locally interpolating pixel regions. Ink-jet recording method, characterized in that the effective ink landing position is controlled by the temperature of the recording head and / or the environmental temperature. 10. The ink jet recording method according to claim 9, wherein the timing of ejecting ink is controlled according to the temperature of the recording head and / or the environmental temperature. 11. The ink jet recording method according to claim 9, wherein the driving conditions of the recording head are changed according to the temperature and / or the environmental temperature of the recording head. 12. The ink jet recording method according to claim 10, wherein the timing at which the ink is ejected is changed at the head of scanning by the recording head. 13. The inkjet recording method according to claim 11, wherein the driving condition is changed by changing the pulse width. 14. The ink jet recording method according to claim 11, wherein the driving condition is changed by changing the divided pulse. 15. The ink jet recording method according to claim 12, wherein the timing of ejecting ink is changed during forward printing and / or backward printing. 16. The ink jet recording method according to claim 12, wherein the timing of ejecting ink is changed only at the head of the page to be printed.