JP2002210931A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recorder capable of performing high quality printing in a short time. SOLUTION: This ink jet recorder comprises a recording head 1 having a plurality of nozzles for ejecting ink and a common liquid chamber for supplying ink to the plurality of nozzles, and an ejecting means for ejecting the ink from the plurality of nozzles on the recording head 1. Each of the nozzles is equipped with a plurality of ink ejection holes 2-5.

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 which performs recording by discharging ink from a recording head onto a recording material.

[0002]

2. Description of the Related Art Recording devices such as printers, copiers, and facsimile machines are configured to record an image formed of a dot pattern on a recording material such as paper or a thin plastic plate based on image information.

Incidentally, this type of recording apparatus can be classified into an ink jet type, a wire dot type, a thermal type, a laser beam type and the like according to the recording method. Ink (recording liquid) droplets are ejected and fly, and are attached to a recording material to perform recording.

[0004] A system (bubble jet system) in which an electrothermal conversion element (heater) is provided in a nozzle of a recording head and energized to generate heat, and the ink is ejected and fly by the expansion force of bubbles generated by the heat, The size of the electrothermal conversion element (heater) provided in each discharge port is much smaller than that of a conventionally used piezoelectric element, and high-density multiple discharge ports can be realized.

FIGS. 15 to 19 are diagrams for explaining the prior art.

FIG. 15 is a front view of the recording head 1001 as viewed in a direction in which ink flies to this side. In FIG. 15, reference numeral 1002 denotes nozzles, and the number of nozzles 1002 formed on the recording head 1001 is assumed to be eight for the sake of simplicity.

During printing, ink is ejected while performing main scanning in the BB 'direction in the drawing, and when printing for the width of all the nozzles 1002 is completed, the recording head 1001 returns to the initial position and is printed. The medium, which is the medium, is fed in the direction perpendicular to the main scanning by the width of all the nozzles 1002 of the print head 1001, and prints the next place. This is repeated to form an image.

Next, the structure of the nozzle 1002 will be described.

FIG. 16 shows the nozzle 10 of the recording head 1001.
Sectional view of main part 02 (sectional view taken along line BB 'in FIG. 15)
In the figure, reference numeral 1002 denotes a nozzle as an ink discharge port, 1003 denotes a hollow liquid chamber, and 1004 denotes an electrothermal conversion element (heater).

Next, the recording head 100 will be described with reference to FIG.
Operation 1 will be described. As shown in FIG. 7A, when electricity is supplied to the electrothermal conversion element 1004 to generate heat, water, which is a main component of the ink 1006, is vaporized to become water vapor.
In the figure, reference numeral 1005 denotes the gas, which is a bubble.

When energization of the electrothermal conversion element 1004 is continued, as shown in FIG.
Of ink 1006 with nozzle (ejection port) 1002
Press it. After that, when the energization is further continued, FIG.
The ink 1006 flies from the nozzle 1002 as shown in FIG.

When the energization of the electrothermal conversion element 1004 stops,
The liquid chamber 1003 is filled with the ink 1006 by the refill (the nozzle 1002 is filled with the ink 1006 by a capillary phenomenon), and is ready for the next ejection.

When one ink 1006 is ejected and landed on the medium, the spread of the ink 1006 becomes the ink 1
006. This is called a droplet.
FIG. 18 shows the outline.

FIG. 19 shows droplets when all the nozzles are ejected by the recording head shown in FIG. 15 and scanning is performed in the main scanning direction.

[0015]

One of the problems in recording an image having a gradation by the ink jet method is that a highlight portion of an image (that is, an optical density (hereinafter, referred to as an optical density)) is used.
(Hereinafter referred to as “OD”).

When printing is performed using the above-described conventional recording head and viewed at a closer distance, if the dot diameter is large and the dot OD is high, each dot will be seen, resulting in a so-called granular feeling (which is originally smooth). (That the image to be seen looks rough).

In the prior art, since the amount of ink discharged is large, droplets become large, graininess is deteriorated, and image quality is reduced. As a countermeasure against this, it is conceivable to reduce the dot diameter by reducing the ink ejection amount. For this purpose, a smaller recording head may be made, but it is technically difficult to make a fine head. Further, in order to obtain an ink density equivalent to that of a recording head having a large discharge amount, the print density must be increased by the amount corresponding to the decrease in the discharge amount, and there has been a problem that increasing the print density increases the print time.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an ink jet recording apparatus capable of performing high-quality printing in a short time.

[0019]

According to an aspect of the present invention, there is provided a recording head having a plurality of nozzles for ejecting ink and a common liquid chamber for supplying ink to the plurality of nozzles. An ink jet recording apparatus is configured to include an ejection means for ejecting ink from a plurality of nozzles of the recording head, and a plurality of ink ejection ports are provided for each nozzle.

According to a second aspect of the present invention, there is provided a recording head having a plurality of nozzles for ejecting ink arranged in a line perpendicular to the main scanning direction and having a common liquid chamber for supplying ink to the plurality of nozzles. An ink jet recording apparatus was configured to include an ejection unit that ejects ink from a plurality of nozzles of a recording head, two ink ejection ports were provided for each nozzle, and the ink ejection ports were arranged in the direction in which the nozzles were arranged. Features.

Therefore, according to the first aspect of the present invention, a high quality image can be formed by fine ink droplets by ejecting a plurality of ink droplets from the ejection means.

According to the second aspect of the present invention, the printing density can be increased by dividing and ejecting ink droplets from one nozzle in the direction in which the nozzles are arranged.

[0023]

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

<Embodiment 1> FIG. 1 is a front view of a recording head of an ink jet recording apparatus according to the present invention,
FIG. 2 is a cross-sectional view taken along line AA ′ of FIG. 1 as viewed in a direction in which the ink flies to this side.

In FIG. 1, 1 is a recording head, 2, 3,
4 and 5 are discharge ports, and one nozzle is constituted by the four discharge ports 2, 3, 4, and 5. Here, for simplicity of explanation, the number of nozzles of the recording head 1 is assumed to be eight.

During printing, ink is ejected while performing main scanning in the AA 'direction in FIG. 1, and when printing is completed for the width of all nozzles, the recording head 1 returns to the initial position, and the medium to be printed is printed. Is sent by the entire nozzle width of the recording head 1 in the direction perpendicular to the main scanning, and the next portion is printed.
By repeating this, an image is formed.

Next, the structure of the nozzle will be described with reference to FIG.

As described above, reference numerals 2, 3, 4, and 5 are ink discharge ports, and these four discharge ports 2 to 5 constitute one nozzle. Reference numeral 6 denotes a water-repellent surface,
Water-repellent treatment is performed so that the inks adjacent to each other are not combined by surface tension.

Reference numeral 7 denotes a hollow liquid chamber, and reference numeral 8 denotes an electrothermal conversion element (heater).

Next, the operation of the recording head 1 will be described with reference to FIG.

As shown in FIG. 3A, the inner surface of the liquid chamber 7 has been subjected to a hydrophilic treatment, and the ink supplied from the upper part of the figure is refilled by capillary action to fill the liquid chamber 7.

As shown in FIG. 3B, the electrothermal conversion element 8
When this is heated to generate heat, water, which is the main component of the ink, is vaporized to become water vapor. Incidentally, 9 is the gas, which becomes bubbles.

Then, when the energization is continued, the inks 10 and 11 are pushed to the ejection ports 2 to 5 by the expansion force of the bubbles 9 as shown in FIG. After that, if you continue energizing,
As shown in FIG. 3D, the inks 10 and 11
Fly from ~ 5. At this time, ink droplets for several minutes of the ejection ports 2 to 4 are ejected. When the energization of the electrothermal conversion element 8 is stopped, the liquid chamber 7 is filled with ink by refilling (the nozzle is filled with ink by capillary action) and is ready for the next ejection.

In the present embodiment, since four inks are ejected from one nozzle and landed on the medium, one large dot is conventionally used instead of one large dot.
It is formed as small dots.

FIG. 4 shows the outline of a droplet formed by one nozzle. Four ink droplets are landed with a slight shift by one nozzle, and four small droplets are formed.

FIG. 5 shows droplets when all the nozzles are ejected by the recording head 1 shown in FIG. 1 and scanning is performed in the main scanning direction. Compared to the image shown in FIG. 17, the image formed in the present embodiment has less graininess and a high quality image is formed.

In the present invention, since it is sufficient that one nozzle has a plurality of discharge ports, a bubble jet (registered trademark) is required.
It can be applied not only to the printing method of the system, but also to a printing apparatus of a piezo method using a piezoelectric element (a method of ejecting ink by increasing vibration or pressure in a liquid chamber using an element that can be changed by electricity such as piezo). is there.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIGS.

FIG. 6 is a front view of the recording head 1 according to the present embodiment, and is a view as seen in a direction in which ink flies to this side.

The recording head 1 according to the present embodiment differs from the recording head 1 according to the first embodiment in that two nozzles 2, 3 form one nozzle. The other configuration is the same, and the description is omitted.

FIG. 7 shows the outline of a droplet formed by one nozzle. Two small droplets are formed by landing two inks with a slight shift by one nozzle.

FIGS. 8 and 9 show the recording head 1 shown in FIG.
Shows droplets when all the nozzles are ejected and scanning is performed in the main scanning direction. However, since the droplets are spread in the direction in which the nozzles are arranged, a vertical streak is simulated. Therefore, if the resolution in the horizontal direction is doubled, the image formed in the present embodiment has less graininess and a high-quality image is formed as compared with the conventional image shown in FIG.

In this embodiment, two ink ejection ports are provided for each nozzle, and the ink ejection ports are arranged in the direction in which the nozzles are arranged. One is acceptable. FIG. 10 is a front view of the recording head 1, as viewed in a direction in which ink flies to this side. The operation of the recording head 1 is the same as that described above, and a description thereof will be omitted.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIG.

FIG. 11 shows a recording head 1 according to this embodiment.
FIG. 5 is a front view of the ink jet printer viewed from a direction in which the ink flies to this side. The difference between the recording head 1 according to the present embodiment and the recording head 1 according to the first embodiment is the shape of the ejection ports 2 to 5, and the separation between the ejection ports 2 to 5 is narrowed. Others are the same, and the description is omitted.

The outline of the droplet formed by one nozzle is the same as that shown in FIG. The droplets ejected from all nozzles and scanned in the main scanning direction are the same as those shown in FIG.

Each discharge port 2 is placed on the electrothermal conversion element (heater).
There are ~ 5 breaks. This is thinner than in the first embodiment in order to prevent breakage by the force of bubbles generated at the time of ejection.

<Fourth Embodiment> Next, a fourth embodiment of the present invention will be described with reference to FIGS.

FIG. 12 shows a recording head 1 according to this embodiment.
FIG. 5 is a front view of the ink jet printer viewed from a direction in which ink flies to this side.

The difference between the recording head 1 according to the present embodiment and the recording head 1 according to the first embodiment is that seven nozzles 2 constitute one nozzle. Since the configuration is the same, the description is omitted.

When seven inks are ejected from one nozzle and land on the medium, seven small dots are formed instead of one large dot in the related art. FIG.
Indicates the outline of the droplet formed by one nozzle. With one nozzle, seven inks land with a slight shift, and seven small droplets are formed.

FIG. 14 shows a recording head 1 according to this embodiment.
5 shows droplets when all nozzles are ejected and scanning is performed in the main scanning direction. However, compared to the image shown in FIG. It becomes an image.

[0053]

As is apparent from the above description, claim 1
According to the invention described above, by discharging a plurality of ink droplets from the discharging unit, it is possible to obtain an effect that a high-quality image can be formed by fine ink droplets.

Further, according to the second aspect of the present invention, it is possible to increase the print density by dividing and ejecting ink droplets from one nozzle in the direction in which the nozzles are arranged.

[Brief description of the drawings]

FIG. 1 is a front view of a recording head according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line A-A 'of FIG.

FIG. 3 is an operation explanatory diagram of the recording head according to the first embodiment of the present invention.

FIG. 4 is a diagram showing droplets with one nozzle in the recording head according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating an image sample printed by the recording head according to the first embodiment of the present invention.

FIG. 6 is a front view of a recording head according to Embodiment 2 of the present invention.

FIG. 7 is a diagram showing droplets with one nozzle in a recording head according to Embodiment 2 of the present invention.

FIG. 8 is a diagram illustrating an image sample printed by the recording head according to the second embodiment of the present invention.

FIG. 9 is a diagram illustrating an image sample printed by the recording head according to the second embodiment of the present invention.

FIG. 10 is a front view of a recording head according to a modification of the second embodiment of the present invention.

FIG. 11 is a front view of a recording head according to Embodiment 3 of the present invention.

FIG. 12 is a front view of a recording head according to Embodiment 4 of the present invention.

FIG. 13 is a diagram showing droplets with one nozzle in a recording head according to Embodiment 4 of the present invention.

FIG. 14 is an image sample diagram printed by a recording head according to Embodiment 4 of the present invention.

FIG. 15 is a front view of a conventional recording head.

16 is a sectional view taken along line B-B 'of FIG.

FIG. 17 is a diagram illustrating the operation of a conventional recording head.

FIG. 18 is a diagram showing droplets of one nozzle in a conventional recording head.

FIG. 19 is a diagram illustrating an image sample printed by a conventional recording head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording head 2-5 Discharge port of nozzle 6 Water-repellent surface 7 Liquid chamber 8 Electrothermal transducer (heater)

Claims (2)

[Claims] A recording head having a plurality of nozzles for discharging ink, a common liquid chamber for supplying ink to the plurality of nozzles, and a discharge unit for discharging ink from the plurality of nozzles of the recording head; An ink jet recording apparatus comprising a plurality of ink ejection ports provided for each nozzle. 2. A recording head having a plurality of nozzles for ejecting ink arranged in a line perpendicular to the main scanning direction and having a common liquid chamber for supplying ink to the plurality of nozzles, and a plurality of nozzles of the recording head An ink jet recording apparatus comprising: a discharge unit for discharging ink from a nozzle; two ink discharge ports provided for each nozzle; and the ink discharge ports being arranged in the direction in which the nozzles are arranged.