JPH10286966A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make shift of ink dot or color inconspicuous even when there is periodical variation of a moving position of a recording head section in a main scanning direction. SOLUTION: This recorder comprises a recording head section 3 having a plurality of ejection nozzles 24 arranged in a main scanning direction and a moving means that reciprocates the recording head section 3 in the main scanning direction. An arrangement interval of the ejection nozzles 24 is set corresponding to a cycle of periodical variation of the moving position of the recording head section 3 by the moving means. As a result, a relative shift of the position of the ink dot by each of the ejection nozzles 24 is reduced even when the periodical variation of the moving position is generated.

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 recording an image by flying ink droplets, and more particularly to an ink jet recording apparatus having a recording head section provided with a plurality of ejection nozzles in the main scanning direction. It is.

[0002]

2. Description of the Related Art Conventionally, there has been known an ink jet printer which performs image recording by sequentially feeding recording sheets in a sub-scanning direction while reciprocating a carriage on which a recording head is mounted in a main scanning direction. The recording head has an electromechanical conversion type that changes the volume by a piezoelectric element to fly ink droplets, or an electrothermal conversion type that generates bubbles by a heating element and causes the ink droplets to fly based on the volume change. Etc. are known.

In this type of ink jet printer, a plurality of ejection nozzles are provided in a recording head portion in a main scanning direction,
There are known ones in which printing of a plurality of lines can be performed by one main scan to increase the printing speed, and color printing is performed by causing ink of a different color to fly from each ejection nozzle.

[0004]

Incidentally, the positional accuracy of the recorded ink dots depends on various factors such as unevenness of the moving speed of the carriage in the main scanning direction, the flying angle of the ink droplet from the discharge nozzle, and the variation of the flying speed. Although it is disturbed, in particular, many of the causes of unevenness in the moving speed of the carriage have periodicity, which causes periodic variations in ink dot positions. In the case where a plurality of ejection nozzles are provided in the main scanning direction as described above, there is a problem that the variation of the periodic ink dot position is particularly easily noticeable to human eyes.

For example, when recording is performed by a recording head unit provided with two discharge nozzles in the main scanning direction, if the ink dot positions periodically vary, as shown in FIG. The positions are indicated by circles and triangles, resulting in a stripe pattern that is very noticeable.In addition, if the colors of the inks ejected by both ejection nozzles are different, the composite colors will be clearly different. However, there is a problem that it becomes more noticeable.

In view of the above-mentioned conventional problems, the present invention provides an ink jet recording apparatus in which ink dot shift and color shift are hardly noticeable even if the moving position of the print head in the main scanning direction has a periodic variation. It is intended to be.

[0007]

According to the present invention, there is provided an ink jet recording apparatus comprising: a recording head provided with a plurality of ejection nozzles in the main scanning direction; and a moving means for reciprocating the recording head in the main scanning direction. In addition, the discharge nozzle interval is set in accordance with the period of the periodic variation of the moving position of the recording head unit by the moving unit.

According to this, since the interval between the ejection nozzles is made to correspond to the cycle of the variation of the movement position, even if the movement position has a periodic variation, the relative position of the ink dot position by each ejection nozzle is changed. Since the shift is reduced, the ink dot shift and the color shift can be made less noticeable.

In the case where there is a plurality of periodic variations, the ink dot shift and the color shift can be effectively made less noticeable by setting the ejection nozzle interval to a common multiple of each cycle.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An ink jet printer according to an embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, which shows a schematic structure of a main mechanism of the ink jet printer 1, reference numeral 2 denotes a carriage.
A recording head unit 3 is mounted, and a plurality of ink tanks 4 (A, B) for supplying a predetermined color ink to the recording head unit 3 are detachably mounted. The carriage 2 is supported by a lower guide means 5 and an upper guide means 6 so as to be able to reciprocate along a predetermined moving path parallel to the recording surface of the recording sheet 10, and a driving pulley 8 is driven by a driving motor 7.
a, the tension pulley 8b, and the timing belt 9 to reciprocate. The lower guide means 5 supports the carriage 2 movably only in the direction of the movement path, and the upper guide means 6 supports the carriage 2 movably in the direction of the movement path of the carriage 2 and in the vertical direction.

Reference numeral 11 denotes a platen which also serves as a guide plate for guiding the recording sheet 10 along the conveyance path, and 12 denotes a platen 1
The recording sheet 10 is sent to a recording unit where the recording head unit 3 and the platen 11 are opposed to each other by a paper feeding device or a manual feed. At this time, the rotation amount of a paper feed roller (not shown) is controlled by the control unit, and the conveyance to the recording unit is controlled. The recording sheet 10 on which an image has been recorded by the recording head unit 3 in the recording unit is discharged by a discharge roller 13 and a spur roller 14. Reference numeral 15 denotes a recovery system for cleaning the surface of the recording head unit 3 from which ink is ejected to prevent ink ejection failure, and reference numeral 16 denotes a paper feed knob 16 for manually conveying the recording sheet 10.

At the time of recording, the driving motor 7 and the driving pulley 8
The carriage 2 is main-scanned in the width direction of the recording sheet 10 by a, the tension pulley 8b, and the timing belt 9,
An image for one or a plurality of lines is recorded by a recording head unit 3 mounted on the carriage 2. Each time recording by one main scan is completed, the recording sheet 10 is sent in the vertical direction and is sub-scanned. The image is recorded on the recording sheet 10 in this manner, and the recording sheet 10 that has passed through the recording section is discharged by the discharge roller 13 disposed downstream of the conveyance direction and the spur roller 14 pressed against the discharge roller 13.

As shown in FIG. 2, the recording head unit 3 includes:
Three recording head units 21, 22, and 23 corresponding to the three colors of yellow (Y), magenta (M), and cyan (C) are arranged in parallel at appropriate intervals in the moving direction of the recording head unit 3. It is arranged. In each of the recording head units 21 to 23, an ejection nozzle array 25 in which a plurality of ejection nozzles 24 are arranged at appropriate intervals in a direction orthogonal to the moving direction of the recording head unit 3 is provided at an appropriate interval in the moving direction of the recording head unit 3. Are formed in a plurality of rows. Discharge nozzle row 25,
The interval between the recording head units 21 to 23 is set to a, and the interval between the recording head units 21 to 23 is set to b.

Here, in the moving means of the recording head unit 3 comprising the driving pulley 8a, the tension pulley 8b, and the timing belt 9 driven by the driving motor 7, as shown in FIG. And the center of the tension pulley 8b is eccentric with respect to the rotation axis,
Period of each revolution of the drive pulley 8a, i.e. the pitch circle diameter as D _1, as shown in FIG. 3 (b), the variation occurs in the moving position in a cycle of [pi] D _1. In the illustrated example, a pulley having a tooth pitch of 2 mm and a number of teeth of 13 is used.
The movement position varies in a sinusoidal waveform at a cycle of mm. Similarly, for the tension pulley 8b,
Assuming that the pitch circle diameter is D ₂ , the movement position varies at a period of πD ₂ . Further, due to the vibration generated by the teeth of the timing belt 9 successively meshing with the teeth of the pulley 8a, as shown in FIG.
Even in the period of, the movement position varies.
In the illustrated example, the movement position varies at a cycle of the tooth pitch of 2 mm. Since variations in the movement position due to the eccentricity of the pulleys 8a and 8b and the meshing vibration of the timing belt 9 are combined and appear, the recording head unit 3 has a variation in the movement position as shown in FIG. Will be.

Therefore, the interval a between the discharge nozzle rows 25 is set to 2 mm in accordance with the period of the movement position variation due to the tooth pitch of the timing belt 9 of 2 mm. That is, since the dot unevenness with a period of several mm is easily conspicuous, the interval between the single color ejection nozzle rows 25 is 25 mm.
As this cycle. The interval b between the recording head units 21 to 23 is set to 26 mm in accordance with the cycle of the movement position variation due to the eccentricity of the pulleys 8a and 8b. In other words, it is inconspicuous because the cycle is large, but if the color is different, it will be clearly misaligned as a composite color,
The recording head units 21 to 2 of each color are set in accordance with the cycle.
3 are set.

As described above, according to the present embodiment, even if there is a periodic shift in the moving position of the recording head unit 3 in the main scanning direction, ejection is performed at intervals in the main scanning direction in accordance with the period. Since the nozzle rows 25 are arranged, the relative displacement of the ink dot positions by the discharge nozzle rows 25 is reduced, and the ink dot displacement and the color displacement can be hardly noticeable.

The cause of the periodic variation in the movement position is, in addition to the above, resonance of the chassis, the tension belt 9, and the carriage 2 itself, which are caused by the vibration of the drive motor 7. When there are a plurality of periodic factors in this way, the common multiple of each
4 and the arrangement intervals of the ejection nozzle rows 25, it is possible to effectively reduce periodic and noticeable ink dot deviation and color unevenness.

[0019]

According to the present invention, as is apparent from the above description, a recording head in which a plurality of ejection nozzles are arranged in the main scanning direction, and a movement for reciprocating the recording head in the main scanning direction. Means, the discharge nozzle interval is set in accordance with the period of the periodic variation of the moving position of the recording head unit by the moving means, so that the interval of the discharge nozzles Even if there is a periodic variation in the moving position of the recording head due to the corresponding period, the relative displacement of the ink dot position by each ejection nozzle is reduced,
Ink dot deviation and color deviation can be hardly noticeable.

In the case where there are a plurality of periodic variations, setting the interval between the ejection nozzles to a common multiple of each cycle can effectively prevent ink dot shift and color shift from being noticeable.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a schematic configuration of a main mechanism of an ink jet printer which is an embodiment of an ink jet recording apparatus of the present invention.

FIG. 2 is a perspective view showing an arrangement state of ejection nozzles in the print head unit of the embodiment.

FIG. 3 is a diagram showing a state where a periodic variation of a moving position of a recording head unit by a moving unit according to the embodiment occurs;
(A) is an explanatory view of the moving means, (b) is a graph showing periodic variations due to eccentricity of the pulley, (c) is a graph showing periodic variations due to the tooth pitch of the timing belt, and (d) is a pulley. 9 is a graph showing a variation obtained by synthesizing a periodic variation due to the eccentricity and the tooth pitch.

FIG. 4 is an explanatory diagram illustrating a state in which ink dot shift and color shift are easily noticeable when there is a periodic variation in the movement position of the recording head unit in the main scanning direction.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Ink-jet printer (ink-jet recording device) 3 Recording head part 7 Drive motor 8a Drive pulley 8b Tension pulley 9 Timing belt 21 Recording head unit 22 Recording head unit 23 Recording head unit 24 Discharge nozzle 25 Discharge nozzle row

Claims (2)

[Claims] A recording head provided with a plurality of ejection nozzles in a main scanning direction; and a moving means for reciprocating the recording head in the main scanning direction, wherein a moving position of the recording head by the moving means is determined. An ink jet recording apparatus, wherein the discharge nozzle intervals are set in accordance with the period of the periodic variation. 2. When there are a plurality of periodic variations,
2. The ink jet recording apparatus according to claim 1, wherein the interval between the discharge nozzles is set to a common multiple of each cycle.