JP2004358874A - Line head and inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a line head whereby it is possible to reduce the cost of replacement of the line head because of a defective image caused by malfunction of a nozzle and to improve the reliability at a low cost, and to provide a line type inkjet recorder having the same. <P>SOLUTION: This line head 2 has a plurality of nozzles 21a arranged in a length corresponding to a width of a recording medium and records an image by ejecting ink toward the recording medium from the nozzles 21a. The line head 2 consists of a plurality of head units 21 each having the plurality of nozzles 21a arranged therein, the head units being divisionally formed to be arranged along the longitudinal direction. Each of the head units 21 is independently detachable. This inkjet recorder is equipped with the line head 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a line head and an inkjet recording apparatus, and more particularly, a plurality of nozzles are arranged in a length corresponding to a width of a recording medium, and an image is recorded by discharging ink from the nozzles toward the recording medium. The present invention relates to a line head and a line type ink jet recording apparatus provided with the line head.
[0002]
[Prior art]
In the inkjet recording apparatus, one line of image recording was performed by moving the recording head in the main scanning direction while discharging small droplets of ink, which were subjected to ejection control by image signals from nozzles of the recording head, to the recording medium. Thereafter, the recording medium is conveyed by one line in the sub-scanning direction, and small droplets of ink are ejected again from the nozzles of the recording head onto the recording medium to record an image for one line. There is one on which an image is formed.
[0003]
Further, as another inkjet recording apparatus, the recording head is formed in a long shape in which nozzles for ejecting ink are arranged at a substantially equal recording pitch to a length of a substantially maximum recording width of the recording medium, and is fixed to the apparatus main body. There is a line head (Patent Document 1). According to this configuration, it is not necessary to move the recording head in the main scanning direction, and the image can be formed only by transporting the recording medium in the sub-scanning direction orthogonal to the main scanning direction. it can.
[0004]
[Patent Document 1] Japanese Patent Application Laid-Open No. 62-161547
[Problems to be solved by the invention]
As described above, in an ink jet recording apparatus having a fixed line head in which the recording head does not move in the main scanning direction, for example, when the nozzles are clogged with dust or the like and ink cannot be ejected (hereinafter, referred to as ink non-ejection), A nozzle in a case where the peripheral portion of the discharge port of the nozzle is wet with ink, the droplet of the discharged ink is pulled toward the ink, and the ink is not recorded at a target position on the recording medium (hereinafter referred to as ink landing bending). If there is such a defect, an image defect occurs in the image formed on the recording medium.
[0006]
More specifically, when ink is not ejected, vertical streaks are formed on the recording medium in the sub-scanning direction. In addition, in the case of the ink landing deflection, as shown in FIG. 4, for example, in the nozzles a to e arranged at an equal pitch s, the ink C ejected from the nozzle c Is formed, and the CC line is formed by the ejected ink points, the CC line approaches the BB line formed in the same manner, and at the same time, from the DD line. As a result, the vertical pitch in the sub-scanning direction is formed as an image formed by the ink dots due to the difference between the line pitches of other AA lines, EE lines, and the like.
[0007]
When an image defect due to such a nozzle defect occurs, a recovery process such as ink suction and wiping of the nozzle surface is generally performed. If the recovery process does not recover, the recording head itself must be replaced. Without it, the problem of image failure could not be solved. However, the line head has a size (length) equivalent to the width of the recording medium, and there is a problem that replacing the entire head is very expensive.
[0008]
The present invention has been made in view of the above problems, and has a line head that can reduce the cost of replacing a line head due to an image defect caused by a nozzle defect and can improve reliability at a low cost. It is another object of the present invention to provide a line type ink jet recording apparatus.
[0009]
Other objects of the present invention will become apparent from the following description of this specification.
[0010]
[Means for Solving the Problems]
The above-mentioned object is solved by the following inventions.
[0011]
The invention according to claim 1 is a line head for recording an image by arranging a plurality of nozzles in a length corresponding to the width of a recording medium, and discharging ink from the nozzles toward the recording medium, A plurality of nozzle units are divided and formed into a plurality of head units, and the plurality of head units are arranged along a length direction, and each of the plurality of head units is configured to be independently detachable. A line head characterized in that:
[0012]
The invention according to claim 2 is the line head according to claim 1, wherein each of the plurality of head units has the same structure.
[0013]
The invention according to claim 3 is the line head according to claim 1 or 2, wherein the plurality of head units are arranged in a staggered manner along a length direction.
[0014]
The invention according to claim 4, further comprising a line head having a plurality of nozzles arranged at a length corresponding to a width of the recording medium, discharging ink from the nozzles toward the recording medium, and connecting the recording medium with the line. A line-type inkjet recording apparatus that forms an image on the recording medium by relatively moving a head in a sub-scanning direction, wherein the line head includes a plurality of head units in each of which a plurality of nozzles are arranged. The inkjet recording apparatus is characterized in that the plurality of head units are divided and arranged in a length direction, and each of the plurality of head units is independently detachably attachable.
[0015]
According to a fifth aspect of the present invention, when a part of the plurality of head units is removed, a capping means for capping a nozzle surface of a remaining head unit which is not removed is provided. Item 5. An ink jet recording apparatus according to item 4.
[0016]
The invention according to claim 6 is the ink jet recording apparatus according to claim 4 or 5, wherein each of the plurality of head units has the same structure.
[0017]
The invention according to claim 7 is the ink jet recording apparatus according to claim 4, wherein the plurality of head units are arranged in a staggered manner along the length direction of the line head. is there.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0019]
FIG. 1 is a perspective view showing a main part of an ink jet recording apparatus according to the present invention. Note that the line type ink jet recording apparatus can record an image by relatively moving the line head and the recording medium in the sub-scanning direction. Here, the relative movement of the line head and the recording medium in the sub-scanning direction will be described using an example in which the line head is fixed and the recording medium is moved in the sub-scanning direction. It may be moved in the sub-scanning direction.
[0020]
In the figure, reference numeral 2 denotes a line head installed in the ink jet recording apparatus 1, which is connected to a control board 4 by a flexible cable 3 as described later in detail. Note that the line head 2 indicated by a dashed line is a schematic diagram, and details of its configuration will be described later. In addition, when performing full-color image recording, for example, a line head for ejecting ink of each color of YMCK is arranged for each color. Here, an example including one line head 2 will be described.
[0021]
The recording medium P is sandwiched between conveyance roller pairs 5b and 5c of a recording medium conveyance mechanism 5 for conveying the recording medium P, and a conveyance motor 5a is directly connected to the shaft of the conveyance roller pair 5b. , The recording medium P is conveyed at a constant speed in the direction indicated by the arrow Y in the figure.
[0022]
In the image recording operation state, the line head 2 is installed so as to face the surface PS of the recording medium P between the pair of transport rollers 5b and 5c as shown in the drawing, and its length direction is indicated by an arrow Y direction. It extends in the arrow X direction in the figure, which is orthogonal to the transport direction of the medium P.
[0023]
In the line head 2, a large number of nozzles are arranged along the X direction on a surface hidden in the drawing facing the surface PS of the recording medium P. The ink is simultaneously ejected from the multiple nozzles to the recording medium P one line at a time in accordance with an image signal from the control substrate 4, so that the recording medium P is conveyed in the direction of the arrow Y and the surface of the recording medium P is coupled. An image is formed on the PS.
[0024]
Further, at the time of an exchange operation to be described later, the line head 2 is moved from the state shown in FIG. 1 in which the nozzle faces the surface PS of the recording medium P by a control unit and a driving unit (not shown) to, for example, To a position (see FIG. 3) rotated 90 degrees toward.
[0025]
The line head 2 is supplied with ink from an ink tank (not shown) through an ink supply pipe.
[0026]
2A and 2B are views for explaining the configuration of the line head 2, wherein FIG. 2A is a view of the line head 2 viewed from the nozzle side, and FIG. 2B is an enlarged view of a portion A in the circle of FIG.
[0027]
The line head 2 is divided into a plurality of head units 21, and a plurality of nozzles 21 a are arranged in each of the plurality of head units 21.
[0028]
The head units 21 are arranged so that the arrangement direction of the nozzles 21a is along the length direction of the line head 2 (the left-right direction in FIG. 2), and each head unit 21 can be detachably attached to one support substrate 22 independently. One line head 2 is constituted by being attached. Here, detachable independently means that attachment and detachment of any one of the head units 21 can be performed independently of attachment and detachment of the other head units 21.
[0029]
In the illustrated example, seven head units 21 are attached to the support substrate 22 to constitute one line head 2, but the number of head units 21 constituting one line head 2 is not particularly limited.
[0030]
In this manner, the line head 2 is divided into a plurality of head units 21 in each of which a plurality of nozzles are arranged, and the plurality of head units 21 are arranged along the length direction. Since each of the nozzles is independently detachable, even if a nozzle that cannot be recovered by the recovery process alone occurs in the line head 2, only the head unit 21 having the nozzle is removed and replaced with a new head unit 21. Since the line head 2 can be returned to a normal state by replacement, it is not necessary to remove and replace the entire line head 2, so that the cost for replacement can be greatly reduced, and reliability is improved at low cost. be able to.
[0031]
Further, even when the removed head unit 21 is discarded, the amount of discard can be greatly reduced as compared with the case where the entire line head 2 is discarded, so that the environmental resistance is improved.
[0032]
The specific configuration for detachably attaching each head unit 21 to the support substrate 22 is not particularly limited. For example, each head unit 21 is fixed to the support substrate 22 with a screw so that it can be easily attached and detached using a tool such as a screwdriver. It can also be fixed detachably.
[0033]
The attachment and detachment of each head unit 21 may be performed in a direction away from the support substrate 22 as shown by a dashed line in FIG. 2A, or an ink ejection direction of each head unit 21 although not shown. May be slid relative to the support substrate 22 along a direction (perpendicular to the illustrated surface).
[0034]
Although not shown, the support substrate 22 is provided with positioning means including grooves, irregularities, steps, and the like for positioning each head unit 21, and each head unit 21 is attached to the support substrate 22 by the positioning means. After it is positioned with respect to the support substrate 22, it is fixed to the support substrate 22. In particular, as shown in this embodiment, when each head unit 21 constituting one line head 2 is mounted on one support substrate 22, the mounting surface of each head unit 21 is made common. Therefore, the positional accuracy of the nozzle row of each head unit 21 can be easily ensured, which is a preferable mode.
[0035]
The head units 21 attached to the support substrate 22 are preferably arranged in a staggered manner on both sides of the support substrate 22 as shown in the figure. As a result, the distance between the adjacent head units 21 on the same surface side of the support substrate 22 can be increased, so that the attaching and detaching work of each head unit 21 can be performed without disturbing the adjacent head unit 21. Can be easily performed.
[0036]
As shown in FIG. 2B, each of the head units 21 arranged in a staggered manner is such that the center line of the rightmost nozzle 21 a of the upper head unit 21 in the drawing is aligned with the leftmost end of the lower head unit 21 in the drawing. The nozzle unit is located at a distance of the nozzle pitch p from the nozzle 21a as shown in the figure. In the same manner, the nozzle rows of the upper and lower head units 21 are arranged with the support substrate 22 interposed therebetween. Accordingly, the nozzle rows of the entire line head 2 are arranged at the same nozzle pitch p along the length direction of the line head 2.
[0037]
It is preferable that each of the head units 21 has the same structure. The same structure means that at least the size of the head unit 21, the number of nozzles, the nozzle pitch, and the mounting structure to the support substrate 22 are all unified. Since each of the head units 21 has the same structure, the production efficiency of the head unit 21 can be increased, and if at least one head unit 21 is stored for replacement, The exchange of the unit 21 can be easily handled.
[0038]
If the inkjet recording apparatus 1 is provided with a plurality of line heads 2, 2,... Corresponding to the respective colors of YMCK, each of the head units 21 of all the line heads 2, 2,. Is a preferable embodiment because one head unit 21 can cope with replacement of any of the head units 21 of any of the line heads 2, 2,....
[0039]
Each head unit 21 is electrically and independently connected to the control board 4 by the above-described flexible cable 3. Although not shown, an ink supply pipe is also provided for each head unit 21 and each ink unit is independently connected to an ink tank.
[0040]
In the line head 2 described above, the configuration for generating energy for discharging ink from the nozzles is not particularly limited. For example, in addition to the method using an electro-mechanical conversion element such as a piezoelectric element, a high voltage method or a heat energy method is used. Any method such as a bubble burst method can be selected. In particular, in the case where a line head is formed using a piezoelectric element, PZT containing lead is generally used for the piezoelectric element, and discarding a large amount of PZT is not environmentally preferable. Therefore, the present invention, in which the line head 2 can be replaced for each individual head unit 21 and the amount of disposal thereof can be greatly reduced, is particularly effective.
[0041]
Next, an operation example when replacing the head unit 21 in the inkjet recording apparatus 1 will be described.
[0042]
First, the inkjet recording apparatus 1 is set to an operation state, a mode is changed from an operation display unit (not shown), and a user performs an operation to enter a head replacement mode. With this operation input, the control unit of the inkjet recording apparatus 1 operates the inkjet recording apparatus 1 in the head exchange mode. At this time, the line head 2 rotates 90 degrees upward as shown in FIG. Note that the line head 2 shown in FIG. 3 represents a state where the line head 2 shown in FIG. 2 is viewed from the (iii) direction.
[0043]
The ink jet recording apparatus 1 is provided with the same number of capping members (capping means) 6 as individually covering the nozzle surfaces of each head unit 21 when the line head 2 is at the rotated position. . The capping member 6 is formed of a synthetic resin or the like so that the nozzle surface of each head unit 21 can be sealed. When the line head 2 rotates to the state shown in FIG. Then, the nozzle surface is closed and the nozzle surface is closed.
[0044]
Thereafter, the power of the inkjet recording apparatus 1 is turned off under the control of the control unit or the operation of the user. In this power-off state, the user removes the capping member 6 of any of the head units 21 that need to be replaced, removes the head unit 21 from the support substrate 22, and replaces it with a new head unit 21. At this time, since the nozzle surfaces of the remaining normal head units 21 are hermetically sealed by the capping members 6, there is no need to worry about occurrence of clogging due to evaporation of the ink solvent and contamination of the nozzle surfaces.
[0045]
In particular, in the present embodiment, since the head units 21 are arranged in a staggered manner with respect to the support substrate 22, the space for providing the capping member 6 for each head unit 21 is also reduced. There is also an advantage that the capping member 6 can be easily arranged because it can be widely secured without interfering with each other.
[0046]
If the inkjet recording apparatus 1 is provided with a plurality of line heads 2, 2,... Corresponding to the respective colors of YMCK, for example, the other line heads 2, 2,. It is preferable that the nozzle surface of each head unit 21 is also hermetically sealed by the capping member 6.
[0047]
When the head unit 21 is replaced, an identification symbol or the like is given to each of the plurality of head units 21 so that each of the head units 21 can be specified. The user may be notified whether the replacement of the 21 is necessary.
[0048]
To replace the head unit 21, first, a cover (not shown) covering the line head 2 is opened, the flexible cable 3 connected to the head unit 21 to be replaced is removed, and the support substrate of the head unit 21 is removed. The head 22 is released from the state of attachment to the head 22. Then, a new head unit 21 is prepared, the cap or tape for protecting the head surface is removed, and the head unit 21 is mounted at an appropriate position on the support substrate 22. Then, the flexible cable 3 is connected and attached to the support substrate 22. Thereafter, the cover (not shown) is closed, and the power of the inkjet recording apparatus 1 is turned on again.
[0049]
At this time, the newly replaced head unit 21 is automatically detected based on the input operation of the user or the judgment of the control unit to determine which of the line heads 2 is the new head unit 21. The ink is supplied to the head unit 21 so that the ink can be ejected. After that, a test print is created by performing cleaning, checking whether there is any abnormality in the ejection of ink droplets. If there is no abnormality in the ejection, an adjustment chart is output, and based on the output result, a new By adjusting the replaced head unit 21, the inkjet recording apparatus 1 is brought into a movable state.
[0050]
【The invention's effect】
According to the present invention, there is provided a line head capable of reducing the cost of replacing a line head due to an image defect due to a nozzle defect, improving reliability at low cost, and a line type ink jet recording apparatus including the same. can do.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a main part of an ink jet recording apparatus according to the present invention. FIG. 2 is a view for explaining a configuration of a line head according to the present invention. FIG. FIG. 3B is an enlarged view of a portion A in the circle of FIG. 3A. FIG. 3 is a diagram showing the operation of the line head. FIG. 4 is a diagram for explaining a landing deflection of ink.
1: inkjet recording apparatus 2: line head 21: head unit 21a: nozzle 22: support substrate 3: flexible cable 4: control substrate 5: recording medium transport mechanism 6: capping member

Claims (7)

A plurality of nozzles are arranged in a length equivalent to the width of the recording medium, a line head that records an image by discharging ink from the nozzles toward the recording medium,
Each of the plurality of nozzles is divided and formed into a plurality of head units, and the plurality of head units are arranged along a length direction, and each of the plurality of head units is configured to be independently detachable. A line head comprising: 2. The line head according to claim 1, wherein each of the plurality of head units has the same structure. 3. The line head according to claim 1, wherein the plurality of head units are arranged in a staggered manner along the length direction. A line head in which a plurality of nozzles are arranged at a length corresponding to the width of the recording medium, and ink is ejected from the nozzles toward the recording medium, and the recording medium and the line head are relatively moved in the sub scanning direction. A line-type ink jet recording apparatus that forms an image on the recording medium by moving the head unit, wherein the line head is divided into a plurality of head units in each of which a plurality of nozzles are arranged, Are arranged along the length direction, and each of the plurality of head units is configured to be independently detachable. 5. The ink jet recording apparatus according to claim 4, further comprising a capping unit for capping a nozzle surface of a remaining head unit when a part of the plurality of head units is removed. The inkjet recording apparatus according to claim 4, wherein each of the plurality of head units has the same structure. 7. The ink jet recording apparatus according to claim 4, wherein the plurality of head units are arranged in a staggered manner along a length direction of the line head.

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