JPH06183003A - Ink jet printer - Google Patents

Abstract

PURPOSE:To protect a recording paper against crumpling or contamination due to ink when printing is carried out at high dot density. CONSTITUTION:A plurality of first heating elements 10a, 10b...10n which heat up upon application of voltage to deliver optimal standard quantity of ink droplet per single print dot are disposed in a plurality of ink channels 9a, 9b...9n of a recording head 7 and a plurality of second heating elements 11a, 11b...11n are also disposed at positions closer to delivery ports 12a, 12b...12n than the first heating elements 10a, 10b...10n. When printing is carried out at high dot density, an applying voltage control circuit 13 applies voltages to desired ones among the plurality of first heating elements and second heating elements 2 arranged in such ink channels as the desired first heating elements are not arranged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention According to the present invention, when a resistance heating element disposed in an ink flow path is energized, an ink droplet is ejected toward a recording sheet from an ink ejection port to perform recording. The present invention relates to an inkjet printer.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 7, an ink jet printer of this type has an ink chamber 14X and a plurality of ink flow paths 9Xa, 9X which communicate with the ink chamber 14X, respectively.
Xb ... 9Xn and the plurality of ink flow paths 9Xa, 9Xb ...
A plurality of ink ejection openings 12Xa, 12Xb ... 12 provided in a row in the arrow Y direction corresponding to the tips of 9Xn.
Xn and a plurality of resistors arranged for each ink flow path 9Xa, 9Xb ... 9Xn, which generate heat when a voltage (driving signal) is applied and eject an ink droplet of an optimum standard amount per dot. Heating elements 10Xa, 10Xb ... 10Xn
And a recording head 7X having the same. The resistance heating elements 10X of the recording head 7X are controlled by the applied voltage control circuit 13X.
When a voltage is applied to each of a, 10Xb ... 10Xn, heat is generated in each resistance heating element 10Xa, 10Xb ... 10Xn to form bubbles in each ink flow path 9Xa, 9Xb. 9Xa, 9X
b ... 9Xn, each resistance heating element 10Xa, 10Xb ... 10
Ink ejection ports 12Xa, 12Xb ... 12Xn rather than Xn
Most of the ink on the side, that is, the optimum standard amount of ink droplets per dot unique to the head,
a, 12Xb ... 12Xn are ejected toward recording paper (not shown).

[0003]

In the above-mentioned conventional ink jet printer, the volume of ink droplets ejected from each ink ejection port is set to the optimum standard value peculiar to the head for each dot and remains unchanged. Therefore, in FIG.
As shown in FIG. 3, when printing with a high density of print dots A, such as a graphic pattern, is performed on the recording paper, the arrangement direction Y of each ink ejection port and the scanning of the carrier (not shown) on which the recording head is mounted. In the direction X, all the printing dots A are overlapped with the adjacent ones, and the amount of ink adhered per unit area of the recording paper is too large. Therefore, wrinkles are generated on the recording paper due to the water content of the ink, or ink is stuck on the back surface of the recording paper. There is a problem that bleeding occurs and the recording paper and the recording paper overlapping the recording paper are soiled.

When printing with a high density of the print head A, in order to prevent the print dots A from overlapping the carrier (not shown) in the scanning direction X, the carrier of the carrier (not shown) is changed according to the print pattern. A method of precisely controlling the scanning amount is conceivable, but this method has not been put to practical use because it involves high cost and difficulty.

The present invention has been made in view of the above problems of the prior art. Even when printing is performed with a high density of print dots, wrinkles do not occur on the recording paper and the recording paper is not stained with ink. It is an object to provide an inkjet printer.

[0006]

The present invention for achieving the above object provides an ink jet printer having a recording head for performing recording by ejecting ink droplets from a plurality of ink ejection ports toward recording paper. The recording head includes an ink chamber, a plurality of ink channels that communicate with the ink chambers, and a plurality of ink ejection ports that are provided in a row corresponding to the tips of the plurality of ink channels. A plurality of first resistance heating elements that are respectively disposed at predetermined portions of each ink flow path and generate heat when a voltage is applied to eject an optimum standard amount of ink droplets per print dot;
Each ink flow path is disposed at a position closer to the ink ejection port than the first resistance heating element, and heat is generated when a voltage is applied to eject an ink droplet of an amount smaller than the optimum standard amount. A plurality of second resistance heating elements for performing printing, a voltage is applied to each of the plurality of first resistance heating elements at a predetermined timing during normal printing, and printing with high print dot density is performed. In this case, a desired first resistance heating element among the plurality of first resistance heating elements and a second resistance heating element disposed in the ink flow path not provided with the desired first resistance heating element are provided. The resistance heating element and the applied voltage control circuit for applying a voltage at a predetermined timing.

Further, in an ink jet printer provided with a recording head for recording by ejecting ink from a plurality of ink ejection ports toward recording paper, the recording head communicates with an ink chamber and the ink chamber, respectively. A first ink flow path portion having a predetermined flow path cross-sectional area for ejecting an optimum standard amount of ink droplets per print dot and a flow path cutoff smaller than the predetermined flow path cross-sectional area A plurality of ink flow paths in which a flow dividing section including a second ink flow path section having an area is formed, and a plurality of ink ejection openings formed in rows corresponding to the tips of the plurality of ink flow paths. An outlet, a plurality of first resistance heating elements that are respectively disposed in each of the first ink flow path portions of the plurality of ink flow paths and generate heat when a voltage is applied, and the plurality of ink flow paths Each second in A plurality of second resistance heating elements, which are respectively disposed for each flow path section and generate heat when a voltage is applied, are provided, and when performing normal printing, the plurality of first resistance heating elements have a predetermined size. When voltage having a high print dot density is applied by applying voltage at each timing, a desired first resistance heating element among the plurality of first resistance heating elements and the desired first resistance heating element A second resistance heating element disposed in the second ink flow path portion of the ink flow path in which no voltage is provided, and an applied voltage control circuit that applies a voltage to each of the second resistance heating elements at a predetermined timing. .

Further, the recording head may be mounted on a carrier which is reciprocally scanned in the width direction of the recording paper.

[0009]

In the invention according to claim 1 configured as described above, when performing normal printing, the applied voltage control circuit:
As in the conventional case, a voltage is applied to each of a plurality of first resistance heating elements for ejecting an optimum standard amount of ink droplets per print dot at a predetermined timing. On the other hand, when performing printing with a high density of print dots, the applied voltage control circuit causes the desired first resistance heating element to be the same as the plurality of first resistance heating elements and the desired first resistance heating element. Voltages are respectively applied at predetermined timings to the second resistance heating element arranged in the ink flow path where the body is not provided. Here, since the second resistance heating element is arranged closer to the ink ejection port side than the first resistance heating element, the ink droplets ejected by energizing the second resistance heating element are the optimum standard. The amount is smaller than the amount, and as a result, the print dots formed by the ink droplets have a small diameter, and the overlap between adjacent print dots is unlikely to occur.

[0010]

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

(First Embodiment) FIG. 1 is a schematic top view of a main portion of a first embodiment of an ink jet printer of the present invention.
Side portions 1 on the left and right sides of the frame 1 as a printer body in the figure
The conveyance roller 2 and the guide shaft 3 are supported on a by extending in the arrow X direction. The carrying roller 2 constitutes a part of a carrying means for carrying the recording paper 4 as a recording medium in the arrow Y direction orthogonal to the arrow X direction. A carrier 6 is supported by the guide shaft 3, and the carrier 6 has a hollow portion 6a in which a recording head 7 to be described later is provided.
The recording paper 4 is reciprocally scanned by a driving means (not shown) along the width direction (direction of arrow X) of the recording paper 4, that is, the guide shaft 3.

A plurality of ink ejection ports (not shown) of the recording head 7 are directed downward, that is, toward the recording paper 4 side. When the carrier 6 is reciprocally scanned in the direction of arrow X, the ink ejection ports of the recording head 7 are ejected. Recording is performed by ejecting ink droplets toward the recording paper 4 at a predetermined timing. A capping position 8 indicated by a chain double-dashed line is set on the right end side of the scanning area of the carrier 6 in the figure.
Is moved to the capping position 8 and the nozzle portion of the recording head 7 is sealed by a cap mechanism (not shown).

Next, with reference to FIGS. 2 and 3, the recording head portion, which is a feature of this embodiment, will be described. 2 is a schematic perspective view of the recording head shown in FIG. 1, and FIG.
FIG. 3 is a diagram showing a vertical cross section of the recording head shown in FIG.

The recording head 7 has an ink chamber 14 to which ink is supplied from an ink tank (not shown), a plurality of ink channels 9a, 9b ... 9n having a rectangular cross section, which communicate with the ink chamber 14, and a plurality of these ink channels. Ink channel 9a,
A plurality of ink discharge ports 12a, 12b provided in a line in the direction of the arrow Y corresponding to the tips of 9b ... 9n, respectively.
... 12n and ink channels 9a, 9b ... 9n, which are respectively arranged at predetermined portions, generate heat when a voltage is applied and eject an optimum standard amount of ink droplets specific to the head per print dot. A plurality of first resistance heating elements 10a, 1
0n, and a voltage is applied to each of the ink flow paths 9a, 9b, ... 9n at positions closer to the ink ejection ports 12a, 12b, ... 12n than the first resistance heating elements 10a, 10b, ... 10n. Then, a plurality of second resistance heating elements 11a, 11b ... 11n for generating heat and ejecting ink droplets of an amount smaller than the optimum standard amount are provided.

The applied voltage control circuit 13 is provided with a plurality of first resistance heating elements 10a, 10b ... 10n during normal printing.
When a voltage (driving signal) is applied to each of the plurality of first resistance heating elements 10a, 10b, ... The first resistance heating element 10a,
10n and the even or odd-numbered second resistance heating elements 11a, 11b ... 11n are respectively applied with voltage (driving signal) at a predetermined timing. The applied voltage control circuit 13 is provided in a CPU (not shown) that controls each part of the printer.

Next, the operation of this embodiment will be described with reference to FIGS. 1, 2 and 3. When performing normal printing, the applied voltage control circuit 13 causes the carrier to be applied to the plurality of first resistance heating elements 10a, 10b ... 10n for ejecting an optimum standard amount of ink droplets per print dot as in the conventional case. Voltages are applied at predetermined timings in accordance with the scanning of 6.

On the other hand, as shown in FIG. 4, when performing printing with a high density of print dots, the applied voltage control circuit 13
Of the plurality of first resistance heating elements 10a, 10b ... 10n, voltages are applied to, for example, odd-numbered first resistance heating elements 10a, 10c ... And even-numbered second resistance heating elements 11b, 11d. . As a result, the ink droplets ejected from the odd-numbered ink ejection ports 12a, 12c ... Become like the printing dots 5a, 5c ... Like the conventional one, and the second resistance heating elements 11a, 11b ... 11n. Are arranged closer to the ink ejection ports 12a, 12b, ... 12n than the first resistance heating elements 10a, 10b, ... 10n, so that the ink droplets ejected from the even-numbered ink ejection ports 12b, 12d. The print amount becomes smaller than the standard amount and becomes small-diameter print dots 5b, 5d ... And these print dots 5b, 5d ... Do not overlap with the print dots 5a, 5c. When the carrier 6 is moved in the direction of the arrow X by a predetermined minute distance, the applied voltage control circuit 13 causes the even-numbered first resistance heating elements 10b, 10d ... And the odd-numbered second resistance heating elements 10b, 10d ... A voltage is applied to each of the bodies 11a, 11c, ..., By this, the print dots 15a, 15b,
15c, 15d ... Are formed. These print dots 1
5a, 15b, 15c and 15d do not overlap with the previously formed print dots 5a, 5b, 5c and 5d. By repeating the above operation, it is possible to prevent the amount of ink adhered per unit area of the recording paper from being too large.

(Second Embodiment) FIG. 5 is a view showing a longitudinal section of a recording head and an applied voltage control circuit in a second embodiment of an ink jet printer of the present invention, and FIG. 6 is a section taken along the line AA of FIG. It is a figure.

As shown in each drawing, the recording head 17 communicates with an ink chamber 20 to which ink is supplied from an ink tank (not shown), and communicates with the ink chamber 20, and an optimum standard amount per print dot in the middle. First ink flow path portion 26a having a predetermined width for ejecting ink droplets, and thus a predetermined flow path cross-sectional area, and a first ink flow path portion 26a having a width smaller than the predetermined width. 19n in which a flow dividing portion composed of two ink flow paths 27a is formed, and the tips of the plurality of ink flow paths 19a, 19b, ... 22n and a plurality of ink ejection ports 22a, 22b, ..., 22n, and first ink flow passage portions 26a of the plurality of ink flow passages 19a, 19b.
A plurality of first resistance heating elements 24a, which are arranged for each of them and generate heat when a voltage is applied, and a plurality of ink flow paths 1
19n, each of which has a plurality of second resistance heating elements 25a, 25b, ... 25n which generate heat when a voltage is applied.

During normal printing, the applied voltage control circuit 23 applies a voltage (driving signal) to each of the plurality of first resistance heating elements 24a at a predetermined timing to perform printing with a high print dot density. When performing, for example, an odd-numbered or even-numbered first resistance heating element 24a and an even-numbered or odd-numbered second resistance heating element 25a, 25b ... 25n among the plurality of first resistance heating elements 24a. A voltage (driving signal) is applied to each.

The other structure is the same as that of the first embodiment.

Next, the operation of this embodiment will be described with reference to FIGS. When performing normal printing, a plurality of applied voltage control circuits 23 are provided in each of the first ink flow path portions 26a for ejecting an optimum standard amount of ink per print dot, as in the conventional case. A voltage is applied to the first resistance heating element 24a at a predetermined timing in synchronization with the scanning of the carrier 6.

On the other hand, as shown in FIG. 4, when performing printing with a high density of print dots, the applied voltage control circuit 23
Applies a voltage to, for example, an odd-numbered first resistance heating element 24a and an even-numbered second resistance heating element 25b ... Of the plurality of first resistance heating elements 24a. As a result, the ink droplets ejected from the odd-numbered ink ejection ports 22a become print dots 5a, 5c ... Like the conventional one, and the second resistance heating elements 25a, 25b.
25n is a second ink flow path portion 27a having a flow path cross-sectional area smaller than that of the first ink flow path portion 26a.
, Respectively, the ink droplets ejected from the even-numbered ink ejection ports 22b ... Are smaller than the optimum standard amount, and become small-diameter printing dots 5b, 5d. 5b, 5d ... are print dots 5a,
5c ... Does not overlap. And carrier (not shown)
Is moved by a predetermined distance in the direction of the arrow X, the applied voltage control circuit 23 causes the even-numbered first resistance heating element 24 this time.
a and odd-numbered second resistance heating elements 25a ... 25n are respectively applied with voltages, whereby the print dots 15a, 1
5b, 15c, 15d ... Are formed. These print dots 15a, 15b, 15c, 15d do not overlap with the print dots 5a, 5b, 5c, 5d previously formed. By repeating the above-described operation, it is possible to prevent the amount of ink adhered per unit area of the recording paper from being too large.

In each of the above-described embodiments, when printing is performed with a high density of print dots, ink droplets of a smaller amount than the optimum standard amount are ejected from every other one of the plurality of ink ejection ports. However, it is not limited to this. That is, first, ink droplets smaller than the optimum standard amount are ejected only from every second or every third ink ejection port (third-th ink ejection port of an integer multiple of 3 or an integer multiple of 4).
If the carrier is scanned and moved by a predetermined minute distance, then an optimum standard amount of ink droplets is ejected only from the ink ejection ports other than the second or third ink ejection ports, and these operations are repeated. Good.

Further, although the recording head in which a plurality of ink ejection openings are formed in one row is shown, the present invention is not limited to this, and the present invention can be applied to a recording head in which a plurality of ink ejection openings are formed in a plurality of rows. . Furthermore, although the recording head is a serial type ink jet printer mounted on a carrier that is reciprocally scanned in the width direction of the recording medium, the present invention is not limited to this, and recording with ink ejection openings formed over the entire width of the recording paper The present invention can be applied to an inkjet printer having a head. Even in these cases, it goes without saying that the print patterns shown in the above-described embodiments are printed.

[0026]

As described above, according to the present invention, when printing is performed with a high density of the print head, an amount of ink droplets smaller than the optimum standard amount peculiar to the head is ejected from a desired ink ejection port. Since it is configured, overlapping of print dots is less likely to occur and the amount of ink droplets attached per unit area of the recording paper is reduced, so that wrinkles do not occur on the recording paper and ink does not bleed on the back surface of the recording paper. Has the effect of not being stained with ink.

[Brief description of drawings]

FIG. 1 is a schematic top view of a main part of a first embodiment of an inkjet printer of the present invention.

FIG. 2 is a schematic perspective view of the recording head shown in FIG.

FIG. 3 is a diagram showing a longitudinal section of the recording head shown in FIG. 2 and an applied voltage control circuit.

FIG. 4 is an enlarged view of a recording sheet when an example of a printing operation with a high dot density is performed by the recording head shown in FIG.

FIG. 5 is a diagram showing a longitudinal section of a recording head and an applied voltage control circuit in a second embodiment of an inkjet printer of the invention.

6 is a cross-sectional view taken along the line AA of FIG.

FIG. 7 is a diagram showing a longitudinal section of a recording head and an applied voltage control circuit in a conventional inkjet printer.

FIG. 8 is an enlarged view of the recording paper when an example of a printing operation with a high dot density is performed by the recording head of the conventional inkjet printer.

[Explanation of symbols]

1 Frame 1a Side part 2 Conveying roller 3 Guide shaft 4 Recording paper 5a, 5b, 5c, 5d, 15a, 15b, 15c, 1
5d printing dot 6 carrier 6a hollow part 7,17 recording head 8 capping position 9a, 9b, 9c ... 9n, 19a, 19b ... 19n
Ink flow paths 10a, 10b, 10c, ... 10n, 24a First resistance heating elements 11a, 11b, 11c ... 11n, 25a, 25b ... 2
5n Second resistance heating element 12a, 12b, 12c ... 12n, 22a, 22b ... 2
2n Ink ejection port 13,23 Applied voltage control circuit 14,20 Ink chamber 26a First ink flow passage portion 27a Second ink flow passage portion X Carrier scanning direction Y Ejection port formation direction, recording paper conveyance direction

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location 9012-2C B41J 3/04 104 H

Claims (3)

[Claims] 1. An ink jet printer comprising a recording head for recording by ejecting ink droplets from a plurality of ink ejection ports toward a recording paper, wherein the recording head communicates with an ink chamber. A plurality of ink flow passages, a plurality of ink ejection openings provided in a row corresponding to the tips of the plurality of ink flow passages, and arranged at each predetermined portion of each ink flow passage, A plurality of first resistance heating elements for generating an optimum standard amount of ink droplets per print dot when a voltage is applied, and ink for each ink flow path rather than the first resistance heating element. And a plurality of second resistance heating elements that are respectively disposed at the positions on the ejection port side and that generate heat when a voltage is applied to eject ink droplets of an amount smaller than the optimum standard amount, When printing , A voltage is applied to each of the plurality of first resistance heating elements at a predetermined timing, and when printing is performed with a high density of print dots, a desired first resistance of the plurality of first resistance heating elements is selected. A heating element and a second heating element disposed in the ink flow path where the desired first resistance heating element is not provided.
And an applied voltage control circuit for applying a voltage to each of the resistance heating elements of the above at a predetermined timing. 2. An ink jet printer including a recording head for performing recording by ejecting ink from a plurality of ink ejection ports toward a recording paper, the recording head communicating with an ink chamber and the ink chamber, respectively. A first ink flow path portion having a predetermined flow path cross-sectional area for ejecting an optimum standard amount of ink droplets per print dot and a flow path cutoff smaller than the predetermined flow path cross-sectional area A plurality of ink flow paths in which a flow dividing section including a second ink flow path section having an area is formed, and a plurality of ink ejection openings formed in rows corresponding to the tips of the plurality of ink flow paths. An outlet, a plurality of first resistance heating elements that are respectively disposed in each of the first ink flow path portions of the plurality of ink flow paths and generate heat when a voltage is applied, and the plurality of ink flow paths Each second ink flow path A plurality of second resistance heating elements, which are respectively arranged for respective parts and generate heat when a voltage is applied, are provided, and at the time of normal printing, the plurality of first resistance heating elements have a predetermined timing. And a desired first resistance heating element among the plurality of first resistance heating elements and the desired first resistance heating element are provided at the time of printing with a high print dot density. An ink jet printer comprising: a second resistance heating element disposed in a second ink flow path portion of the ink flow path not provided; and an applied voltage control circuit for applying a voltage at a predetermined timing, respectively. . 3. The ink jet printer according to claim 1, wherein the recording head is mounted on a carrier that is reciprocally scanned in the width direction of the recording paper.