JPH10119274A - Ink jet printer and driving method for ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform high speed printing of an image having a high density without occurrence of delaying of refilling of ink in an ink jet printer. SOLUTION: In heaters SEG1-SEG4 for ink ejection of an ink jet head, the heaters SEG1 and SEG3 are disposed near an ink supplying hole rather than the other heaters. In a high speed printing mode wherein the speed is two times of that in a normal mode, the above heaters SEG1 and SEG3 are driven by a driving cycle which is two times of that of the other. A delay time corresponding to the differences of the disposing positions of the heaters is set. As a result, it is possible to reduce thinned dots due to the high speed printing in terms of the printed result, thereby preventing lowering of the overall density.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an ink jet printing apparatus and a method of driving an ink jet head.

[0002]

2. Description of the Related Art Various techniques for improving a printing speed in an ink jet printing system have been conventionally known. Among them, a method of increasing the density of ink ejection ports and lengthening the head by arranging a large number of ejection ports in one chip, and a method of increasing the driving frequency by shortening the cycle of the applied pulse applied to the inkjet head A known method is to increase the speed of a carriage on which a head is mounted.

However, the first method of increasing the length of the head among the above methods has a problem that the cost is high.

[0004] The second method of increasing the driving frequency is that a voltage drop occurs when discharging is performed from all the discharge ports, and a pressure fluctuation caused by discharge between adjacent discharge ports causes another discharge port to discharge. In some cases, so-called crosstalk may occur, which affects the ejection of the ink. For example, as an example of the adverse effect due to this crosstalk, there is a problem that the next bubble timing is reached before the ink is refilled in the ink path that causes the ink to foam, and it is not possible to eject ink droplets. On the other hand, in a so-called side shooter type ink jet head in which a discharge port is arranged in a direction facing one surface of a heater that generates thermal energy for foaming, particularly, a distance (hereinafter, referred to as a distance) between the heater and the liquid chamber. , Also referred to as C-H distance) to reduce the flow path resistance, thereby shortening the ink refill time.
That is, it is possible to increase the refill frequency. However, if all the C-H distances are shortened and the discharge is performed simultaneously from the discharge ports, the above-described crosstalk may occur, and problems such as a voltage drop and a decrease in the actual refill frequency may also occur. . It is known that time-division driving is performed in order to prevent the voltage drop problem from occurring. However, the time-division driving shifts the landing positions of the ejected ink droplets by the amount of the ejection timing shift. As a result, a problem arises in that the arrangement of dots formed by this does not become linear.

[0005] A third method is known as a high-speed printing mode or a draft printing mode in a conventional ink jet printer or the like. FIG. 1 shows a case where a solid image to be formed with 10 dots in the main scanning direction and 10 dots in the sub-scanning direction is printed in a normal print mode. In this case, the carriage speed is about 423 mm / sec in the main scanning direction. This is 600 dpi
At a speed of 100 μsec.

FIG. 2 shows a case where the same solid image as that shown in FIG. 1 is printed in the high-speed print mode or the draft print mode, and the carriage speed is doubled to about 846 mm / s.
ec. In these figures, the distance between adjacent dots is twice as long in FIG. 2 since the carriage speed is twice that in FIG.
As described above, in the conventional high-speed printing mode, the printing speed is increased by increasing the carriage speed and thinning out the dots in the main scanning direction. However, this method has a problem that the optical density of the entire solid image is reduced as compared with a normal print mode because dots in the main scanning direction are thinned out.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an ink-jet printing apparatus and a method of driving an ink-jet head which can perform high-speed printing while preventing the above-mentioned problems of the prior art. . That is, an object of the present invention is to provide an ink jet printing apparatus and a method of driving an ink jet head which can perform printing at high density and at high speed without causing crosstalk with a small number of ejection ports.

Another object of the present invention is to drive an ink-jet printing apparatus and an ink-jet head capable of performing high-density printing without shifting the landing position even when time-division driving is performed in a high-speed print mode. It is to provide a method.

[0009]

According to the present invention, there is provided:
A plurality of ink ejection ports and a plurality of energy generating elements for generating energy used for ejecting ink from the plurality of ink ejection ports, and an energy action section corresponding to the plurality of energy generation elements; An inkjet printing apparatus that performs printing by ejecting ink from an inkjet head to a print medium by using an inkjet head having a different distance from an ink supply source to an action unit, wherein the inkjet head performs scanning. Means for driving the inkjet head during the scanning of the inkjet head by the scanning means, and for the drive frequency of each of the plurality of energy generating elements, the shorter the distance, the higher the drive frequency of the energy generating element. And characterized in that:

[0010] More preferably, the apparatus further comprises mode control means for controlling a printing operation in a plurality of printing modes,
The mode control means causes the head driving means to drive at a higher driving frequency for the energy generating element having the shorter distance in the high-speed print mode.

A plurality of ink discharge ports and a plurality of energy generating elements for generating energy used for discharging ink from the plurality of ink discharge ports;
What is claimed is: 1. A method of driving an ink jet head, wherein a distance between an energy application unit of each of the plurality of energy generating elements and an ink supply source to the application unit is different, wherein the driving of the inkjet head is performed during scanning of the inkjet head. In the driving frequency of each of the plurality of energy generating elements, the energy generating element having a shorter distance is driven at a higher driving frequency.

More preferably, in the high-speed print mode among the plurality of print modes, the energy generating element having a shorter distance is driven at a higher drive frequency.

According to the above arrangement, the ink supply source
The energy generating element having a shorter distance to the energy application section for ejection can be driven at a higher frequency. Therefore, even when the head scans at a high speed, the reduction in the ink dot density due to the high-speed scanning can be performed by each drive. It can be suppressed according to the frequency.

[0014]

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

(Embodiment 1) FIG. 3 schematically shows a positional relationship between a discharge heater and an ink supply port of an ink jet head according to a first embodiment of the present invention.
The head shown in the figure is of a side shooter type. It should be noted that, as is clear from the following description, the figure does not correctly represent the actual size relationship for convenience of explanation.

On both sides of the ink supply port 301, heaters SEG1 to SEG128 and SE for generating thermal energy used for discharging each of 128 inks are provided.
G129 to SEG256 are synchronously arranged according to a certain rule. These heaters are provided in ink paths indicated by alternate long and short dash lines in the figure, however, illustration of the ink paths is omitted in the figures referred to below.

That is, first, these heaters are arranged at four different distances from one another for the distance between C and H, that is, the distance from the end of the ink supply port 301 to the center of the heater. It should be noted that the shape of the illustrated heater is for convenience of explanation, and it goes without saying that the actual shape is not limited to such a circular shape.

Next, the width of the opening as the ink supply port 301 is 0.443 mm. With respect to the ink supply port 301, the distance between the left and right heaters SEG2, SEG4,.
mm, on the other hand, the right side heater groups SEG129 to SEG
The distance between C and H of the 256 left-row heaters SEG130, SEG132,... Is set to 0.0985 mm. The left heater group and the right heater group are 0.0425 mm (600 d) in a direction perpendicular to the head scanning direction A or B.
The heaters of each heater group are 300 dpi apart from each other in the vertical direction.
They are arranged at considerable intervals. As a result, printing at 600 dpi can be performed using the respective heater groups in a complementary manner as described later.

Electric wires (not shown) are provided to the respective heaters of each heater group, whereby each heater is selectively driven based on a drive signal. Then, bubbles are generated in the ink using the heat energy generated by the driving of the heater, and the ink is discharged from the discharge ports provided vertically above the heater surface.

Further, in the heater group on each side, the left row heater and the right row heater are each 1200 dp in the scanning direction.
It is provided at a distance corresponding to i. In accordance with such a shift in the scanning direction corresponding to each heater row in each heater group, the heaters in each heater group are time-divisionally driven at two different timings according to the position in the scanning direction.

That is, in this embodiment, printing is performed by ejecting ink in both forward and backward scanning of the head. In the forward scanning in the direction of arrow A in the figure, the left heater group S
Inks are selectively ejected from the corresponding ejection ports using EG1 to SEG128, while ink is ejected using the right heater groups SEG129 to SEG256 in the backward scanning in the direction of arrow B in the drawing.

In this case, in the high-quality print mode, the carriage speed is set at a pitch of 600 dpi for 100 μsec.
423 mm / sec, which passes through the heaters SEG1 and SEG in the forward scan, as shown in FIG.
After driving EG3, SEG5,.
After that, the heaters SEG2, SEG4, SEG6,. On the other hand, in the backward scanning, as shown in FIG. 4B, first, the heaters SEG130, SEG132, SEG13
4, 50 .mu.sec after driving the heaters SEG1.
29, SEG131,... Further, the interval between each heater drive in each of the forward and backward scans is 100 μsec, and therefore, the frequency between each heater is 10 KHz.

As a result, the number of heaters driven at a time can be reduced by time-division driving, and the displacement of the landing position in the scanning direction due to this time-division driving can be prevented. Further, as shown in FIG. Printing can be performed at a resolution of 600 dpi in the scanning direction and a direction perpendicular to the scanning direction.

In the high-speed print mode (draft print mode) of the present embodiment, printing is performed by reciprocal scanning similarly, but the carriage speed is about 846 mm / sec, which is twice that of the high-quality print mode. The driving frequency of each heater is set to SEG2, SEG4,.
, And SEG129, SEG131,... Are driven at a frequency of 10 KHz, while SEG1, SEG1, with a short CH distance are
SEG3,... And SEG130, SEG132,.

FIGS. 6 (A) and 6 (B) are timing charts showing the drive timing of each heater similar to FIGS. 4 (A) and 4 (B).

Performing time-division driving at intervals of 50 μsec by using the left heater group and the right heater group in each of the forward and backward scans is the same as in the above-described high-quality print mode. Heaters SEG1, SEG3,... And heaters SEG130,
The SEGs 132,... Are driven at 20 KHz which is twice the normal value. As a result, the image formed on the recording paper can be printed at a high density of 600 dpi, as shown in FIG. It is possible to print an image with a higher density than the print result of thinning out the dots.

In the high-speed print mode of the present embodiment, some heaters are driven at a relatively high drive frequency of 20 KHz and may cause refill delay. However, these heaters have a short C-H distance. Therefore, it is possible to make it difficult to delay the refill and also to prevent it before it occurs.

(Embodiment 2) FIG. 8 is a diagram schematically showing a heater arrangement and the like of an ink jet head according to another embodiment of the present invention.

In the head of this embodiment, ink supply ports are provided on both sides of the heater, and the distance between them is 20 μm. A heater is provided between the ink supply ports at a pitch of about 3 μm in the scanning direction of the head and in a direction orthogonal to the scanning direction.
The heaters are arranged stepwise at a pitch of 0 dpi, so that the heaters have different C-H distances.

More specifically, as shown in FIG.
G1, SEG2, SEG3, SEG4, SEG5, and SEG6 are arranged stepwise to form one block, and the arrangement of such blocks is periodically repeated, so that a total of 120 heaters in total of 20 blocks are provided. Is provided. An ink ejection port is formed corresponding to each of these heaters, thereby forming an ejection port arrangement similar to the heater arrangement shown in FIG.

As in the first embodiment described above, each heater is provided with an electric wiring (not shown). When a signal is supplied to the heater through this electrode, bubbles are generated in the ink above the heater. The ink is ejected from the corresponding ejection port by the pressure of the bubble.

FIG. 9 shows the waveform of the drive pulse applied to each heater. In the high-speed print mode, the carriage speed is set to about 846 mm / sec as in the first embodiment.
c. At the same time, the heaters SEG1, SEG7,
20K of SEG13,..., SEG115 at the same time
, And after 16.6 μsec, the heaters SEG2, SEG8,.
Drive at 0 KHz. Further, after 16.6 μsec, the heaters SEG3, SEG9,..., SEG117 are simultaneously driven at a frequency of 10 KHz. 16.6 μs
After ec, the heaters SEG4, SEG11, ..., SEG11
8 are simultaneously driven at 10 KHz. The next 16.6
.mu.sec, the heaters SEG5, SEG11,.
EG119 was set to 20 KHz, and the next 16.6 μs
c, the heaters SEG6, SEG12,..., SEG120
At 20 KHz. Thus, 6 of each block
The six heaters are driven at six respective timings at intervals of 16.6 μsec. That is, the heater SEG
1, SEG7, SEG13,..., SEG115 and S
Since EG6, SEG12,..., SEG120 have a short C-H distance, the ink refill time is relatively short.
Therefore, it is driven at a high frequency of 20 KHz. Also,
Heaters SEG2, SEG8, SEG116 and SEG
, SEG11,..., SEG119 have a longer distance between the heaters such as the heater SEG1 by about 3 μm, but have a longer distance between the CHs.
SEG117 and heaters SEG4, SEG11,.
Since the SEG 118 is driven at a lower frequency of 10 KHz, the influence of the driving of the adjacent heater SEG3 or the like on refilling is small, and the delay of refilling is not so large even when driven at 20 KHz.

The print result of the high-speed print mode described above can be a high-density image, as is clear from the dot arrangement schematically shown in FIG.

The print result shown in FIG. 10 can be realized by one-way scanning, unlike the case of the first embodiment.

(Embodiment 3) FIG. 11 is a schematic view showing a heater arrangement and the like of an ink jet head according to still another embodiment of the present invention.

On both sides of the ink supply port 301, 120 heaters SEG1 to SEG120 and heaters SEG121 to SEG240 are periodically arranged according to a certain rule. It should be noted that only six heaters are shown in FIG.

These heaters have a C-H distance of 6
They are arranged at different distances. That is, the width of the ink supply port is 0.443 mm. With respect to the ink supply port 301, the distance between the CHs of the left end row heaters SEG3, SEG6,... Of the left side heater groups SEG1 to SEG120 is 0.136 mm, while the right side heater group SEG12.
1 to SEG240, left end row heaters SEG123, SEG
The distance between C and H of 126,... Is set to 0.0985 mm. The left heater group and the right heater group are 0.0425 mm apart from each other in a direction perpendicular to the scanning direction of the head.
(Equivalent to 600 dpi), and the heaters of each side heater group are 3 ° away from each other in the vertical direction.
They are arranged at a pitch of 00 dpi.

Further, the heaters SEG1, SEG4, SEG4, SEG4,
, SEG123, SEG126, ... and heaters SEG2, SEG5, ..., SEG122, SEG12 in the center row.
The distance in the scanning direction between 5, ... is 0.0005 mm
And the central row heater and the ink supply port 30.
Heaters SEG3, SEG6,..., SEG furthest from
The distance to 121, SEG124, ... is 0.0045mm
It is.

In the above-described heater arrangement, in the present embodiment, the left heaters SEG1 to SEG120 are used in the forward scan.
To the right side heaters SEG121 to SEG24 in the backward scanning.
0, and time-division driving is performed at three different timings.

That is, as representatively shown in FIG.
Three heater groups SEG1, SEG having different C-H distances
2 and SEG3 are a heater SEG1 and a heater SEG2.
Has a delay time of 5 μsec, the heaters SEG1 and SEG3 are driven with a delay time of 20 μsec.
It is driven at 0 KHz, 20 KHz and 10 KHz.
Further, the carriage speed at this time is 1269 mm / sec, which is three times that of normal printing.

FIG. 13 shows the results of printing by the above-described driving method. As shown in FIG. 13, despite thinning the scanning speed three times the normal speed, dot thinning did not occur so much, and the density by high-speed printing was high. Printing without deterioration can be performed.

FIG. 14 is a schematic perspective view showing an example of an ink jet printer which can use the ink jet described in each of the above embodiments.

The ink jet head according to each of the above-described embodiments includes a yellow (Y), a magenta (M), and a cyan (C).
And black (Bk) inks. These four ink jet heads and a tank storing ink to be supplied to these heads are removably mounted on the carriage 12. The carriage 12 includes the guide shaft 1
1 slidably with respect to the guide shaft 11 by a belt 52 running by a motor (not shown).
Can be scanned along. The print medium P is intermittently conveyed along with the scanning of the carriage 12 at a portion facing the ejection port of each ink jet head. That is, the two pairs of transport rollers 15, 16 sandwiching the opposing portion
And 17, 18 are provided, and these are rotated by a motor (not shown) to perform intermittent feeding of the print medium P.

At the home position of the carriage, there is provided a recovery unit 19 for performing an ejection recovery process for each ink jet head.

It should be noted that the operation control of the pudding shown in FIG. 14 and the scanning and ejection driving of the head and the control of the setting of the print mode described in each of the above embodiments are controlled by the CPU.
Of course, it is executed by a known control circuit having

[0046]

As is apparent from the above description, according to the present invention, the energy generating element having a shorter distance from the ink supply source to the energy application section for ejection can be driven at a higher frequency. Even when the head scans at a high speed, a decrease in the ink dot density due to the high-speed scanning can be suppressed in accordance with the respective driving frequencies.

As a result, high-density printing can be performed even in the high-speed print mode without causing a significant decrease in density. In addition, since each of the energy action units that are driven by the high frequency driving is short in distance from the ink supply source, there is no possibility that a delay in refilling occurs.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a printing result in a normal mode by a conventional printing method in a dot arrangement.

FIG. 2 is a diagram schematically showing a printing result in a high-speed mode by a conventional printing method in a dot arrangement.

FIG. 3 is a diagram schematically showing an arrangement and the like of a discharge heater of the inkjet head according to the first embodiment of the present invention.

FIG. 4 is a timing chart showing the driving timing of each heater in the high-quality mode of the first embodiment.

FIG. 5 is a diagram schematically showing a print result in a dot arrangement according to the first embodiment.

FIGS. 6A and 6B are timing charts showing the drive timing of each heater in the high-speed print mode of the first embodiment.

FIG. 7 is a diagram schematically showing a print result in a high-speed mode of the first embodiment in a dot array.

FIG. 8 is a diagram schematically illustrating an arrangement of ejection heaters of an inkjet head according to a second embodiment of the present invention.

FIG. 9 is a timing chart showing the drive timing of each heater in the high-speed print mode of the second embodiment.

FIG. 10 is a diagram schematically showing a print result in a high-speed print mode according to the second embodiment in a dot arrangement.

FIG. 11 is a schematic diagram illustrating an arrangement of ejection heaters of an inkjet head according to a third embodiment of the present invention.

FIG. 12 is a timing chart showing the drive timing of each heater in the high-speed print mode of the third embodiment.

FIG. 13 is a diagram schematically showing a print result in a high-speed print mode of the third embodiment in a dot arrangement.

FIG. 14 is a schematic perspective view illustrating an example of a printer that can perform printing by driving in each of the above-described modes using the inkjet head according to each of the above-described embodiments.

[Explanation of symbols]

 11 Guide shaft 12 Carriage SEG1-SEG256 (for discharge port) heater

Claims (10)

[Claims] A plurality of ink ejection openings, and a plurality of energy generation elements for generating energy used for ejecting ink from the plurality of ink ejection openings. An ink-jet printing apparatus that performs printing by discharging ink from an ink-jet head to a print medium using an ink-jet head having a different distance between an energy action section and an ink supply source to the action section, A scanning unit that performs scanning of the inkjet head performed by the scanning unit, and a driving frequency of each of the plurality of energy generating elements in driving the inkjet head. Head driving means for driving; and Inkjet printing equipment. 2. The method according to claim 1, wherein a distance between each of the energy applying sections and the ink supply source is a distance between each of the energy applying sections and an ink supply port commonly provided for the plurality of energy generating elements. The inkjet printing apparatus according to claim 1, wherein 3. A mode control means for controlling a printing operation in a plurality of print modes, wherein the mode control means provides a higher driving frequency to the head driving means for the energy generating element having the shorter distance in the high speed printing mode. The inkjet printing apparatus according to claim 1, wherein the inkjet printing apparatus is driven. 4. Each of the plurality of energy generating elements is a heater that generates thermal energy, and the inkjet head uses the thermal energy to generate bubbles in the ink and discharges the ink by the pressure of the bubbles. The inkjet printing apparatus according to any one of claims 1 to 3, wherein: 5. The ink jet printing apparatus according to claim 4, wherein said ink jet head has said ink discharge port in a direction perpendicular to a surface of said heater. 6. A plurality of energy generating elements, each of which has a plurality of ink discharge ports and a plurality of energy generating elements for generating energy used for discharging ink from the plurality of ink discharge ports. A method of driving an ink-jet head in which a distance between an energy action part and an ink supply source to the action part is different, wherein each of the plurality of energy generating elements in driving the ink-jet head performed during scanning of the ink-jet head A driving frequency of the energy generating element having a shorter distance, wherein the energy generating element is driven at a higher driving frequency. 7. A distance between each of the energy applying sections and the ink supply source is a distance between each of the energy applying sections and an ink supply port commonly provided for the plurality of energy generating elements. The method for driving an ink jet head according to claim 6, wherein 8. The ink jet head according to claim 6, wherein in the high-speed print mode among the plurality of print modes, the energy generating element having a shorter distance is driven at a higher drive frequency. Drive method. 9. Each of the plurality of energy generating elements is a heater that generates thermal energy, and the inkjet head uses the thermal energy to generate bubbles in the ink and discharges the ink by the pressure of the bubbles. 9. The method of driving an ink jet head according to claim 6, wherein: 10. The method according to claim 9, wherein the ink jet head has the ink ejection port in a direction perpendicular to a surface of the heater.