JP2007090250A - Apparatus and method for forming image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for forming an image capable of highly precisely performing an ink discharge at multi-color high resolution, and further responding without stopping the ink discharge even in the case of discharge failure. <P>SOLUTION: The apparatus for forming an image is provided which forms an image by an ink discharge method, and the apparatus for forming an image comprises a movable flat bed table for placing a substrate which is to carry the image, a plurality of gate stages disposed above the flat bed table, and a plurality of movable ink discharge head units mounted separately on each of the plurality of gate stages. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink ejection method, and more particularly to an image forming apparatus and an image forming method for producing a color filter for optical display, a self-luminous panel, and the like.

Conventionally, when creating a color filter or the like by an ink ejection method, an image is formed by placing a substrate such as glass on a flat bed stage and ejecting ink directly from the ink ejection head unit holding the ink ejection head onto the substrate. A way to go is proposed.
For example, in the case of a color filter, three colors of R (red), G (green), and B (blue) are required. Therefore, ink is discharged for each color using three image forming apparatuses. The color is stored in one unit and discharged simultaneously.

However, in response to the trend of increasing display resolution, such as recent high-definition TVs and displays for mobile applications, it is necessary to increase the discharge resolution of ink discharge. For example, 360 dpi (360 dots / inch, actually 70.6 μm pitch) And 720 dpi (35.3 μm pitch) have been demanded.
However, the discharge resolution of the ink discharge head is limited by each head method from the processing accuracy and discharge performance of the head. For example, 120 dpi or 200 dpi is the maximum resolution that can be realized with one head.
Therefore, for example, in order to realize 480 dpi with a 120 dpi head, it is necessary to make 480 dpi as a set of four heads.

There is also a method to increase the resolution by tilting the head. However, if the scanning width is the same, the same number of nozzles (number of nozzles) will not be changed, so the number of heads actually mounted is the same. Become.
JP 2004-122633 A

When a large number of heads are formed into large-sized ink discharge head units in this way, the weight of the ink discharge head unit becomes, for example, 200 kg or 500 kg, and the size of the ink discharge head unit is considerably large, such as 1 m square. Become.
Therefore, for example, when it is desired to use six colors (C cyan, M magenta, Y yellow in addition to RGB) for the purpose of increasing the color expression range, mounting all the color heads in one ink discharge head unit is extremely However, there is a problem that it becomes a large ink discharge head unit.
Even if a large and heavy ink discharge head unit is made, various accuracy deteriorating factors such as accuracy during transport, relative mechanical accuracy of the ink discharge head unit, and shape accuracy such as its own weight and thermal expansion overlap, resulting in high accuracy. There was a problem that ink could not be ejected.
In addition, if a large number of heads are mounted, there is a problem that the establishment of ejection defects such as nozzle clogging of the ink ejection head increases, and the yield of image formation does not increase.

  The present invention has been made in view of the problems of the related art, and the purpose thereof is to perform multi-color high-resolution ink ejection with high accuracy, and further, without stopping ink ejection even at the time of ejection failure. An image forming apparatus and an image forming method that can cope with the above.

The invention described in claim 1
In an image forming apparatus that forms an image by an ink ejection method,
A movable flat bed table on which a substrate on which the image is formed is placed;
A plurality of portal stages above the flat bed table;
An image forming apparatus comprising: a plurality of ink ejection head units that are independently provided and movable on each of the plurality of portal stages.

The invention described in claim 2
The image forming apparatus according to claim 1, wherein the portal stage includes a deflection correction unit.

The invention according to claim 3
The image forming apparatus according to claim 2, wherein the deflection correcting unit is provided independently for each of the plurality of portal stages.

The invention according to claim 4
The image forming apparatus according to claim 1, wherein the plurality of ink discharge head units are ink discharge head units that discharge different colors of ink.

The invention described in claim 5
5. The image formation according to claim 1, wherein the ink discharge head unit includes a plurality of ink discharge heads capable of discharging two or more colors in one ink discharge head unit. Device.

The invention described in claim 6
4. The image forming apparatus according to claim 1, wherein each of the plurality of ink discharge head units includes an ink discharge head that discharges ink of the same color.

The invention described in claim 7
In an image forming method for forming an image by an ink ejection method,
Preparing to form an image of a predetermined resolution by a combination of ink ejection by a plurality of ink ejection head units;
Detecting a defect of any one of the plurality of ink discharge head units and stopping the use of the defective ink discharge head unit; and
And a step of ejecting ink by combining at least one non-defective ink ejection head unit a required number of times of scanning and a movement for satisfying a predetermined resolution.

According to the first aspect of the present invention, a plurality of ink discharge head units are provided independently on each of the plurality of portal stages. Therefore, even if the weight of one ink discharge head unit is large, the portal stage is not easily bent because, for example, there is only one ink discharge head unit in one portal stage. Therefore, it is easy to secure a necessary interval as the interval between the ink ejection head and the substrate, and the necessary ink ejection accuracy is easily obtained.
Further, when a functional liquid or the like for forming a multicolor discharge or a protective layer is discharged onto the substrate, it can be scanned and discharged independently, so that various discharge patterns can be supported.
Also, the tact time is faster than placing two ink ejection head units on one portal stage.

According to the invention of claim 2, the portal stage has the deflection correcting means. Therefore, even if the portal stage is bent due to the weight of the ink discharge head unit or the like, it can be corrected. Therefore, a necessary interval can be secured as the interval between the ink ejection head and the substrate, and the necessary ink ejection accuracy can be further easily obtained.
In particular, maintaining a narrow gap (referred to as a nozzle gap) between the ink discharge head and the medium (for example, 500 μm, etc.) not only maintains the landing accuracy, but also influences of mist and satellites discharged simultaneously with the ink particles discharged from the ink discharge. It is also important to reduce.
For example, if a 300-500 kg ink discharge head unit is hung on a gate type stage with a iron making structure or a cast structure, depending on the location, a deflection amount of 200-400 μm is generated in the vertical direction due to the deflection of the gate type stage. Therefore, it is very effective for eliminating this bending.

According to the invention of claim 3, the deflection correcting means is provided independently for each of the plurality of portal stages. Therefore, the deflection can be corrected independently for each portal stage. In other words, the portal stage with a large amount of deflection can increase the correction amount, and the portal stage with a small amount of deflection can reduce the correction amount. Completely independent discharge position control is possible. Therefore, it becomes easy to ensure a necessary interval as a distance between all the ink ejection head units and the substrate. Therefore, the required ink ejection accuracy can be easily obtained.
Regardless of the scanning position of each ink discharge head unit, correction control due to the influence of its weight can be performed for each portal stage, so that the nozzle gap can be maintained with very high accuracy.

  According to the invention of claim 4, the plurality of ink ejection head units are ink ejection head units that eject inks of different colors. If each of the plurality of ink discharge head units has a different color, for example, if the first ink discharge head unit is red (R), the second ink discharge head unit discharges in a shared manner such as cyan (C). Therefore, it is effective when the number of colors is large and cannot be placed on one ink discharge head unit. In particular, when there is yellow (Y) depending on the type, such as red, green, blue + yellow (RGB + Y), in the case of a type that does not use yellow (Y) from the viewpoint of preventing the head surface from drying. Since the ink discharge head unit of that color is retracted to the maintenance station and maintenance processing such as capping can be performed, it is very useful for stable operation.

  According to the invention of claim 5, a single ink discharge head unit has a plurality of ink discharge heads capable of discharging ink of two or more colors. For example, red, green, and blue (RGB) can be divided by the first ink discharge head unit, and yellow, magenta, and cyan (YMC) can be discharged by the second ink discharge head unit. The number of head units can be selected from (RGB) three-color ink discharge types and red, green, blue, yellow, magenta, and cyan (RGBYMC) six-color ink discharge types. Therefore, it is possible to prevent problems such as drying nozzles of heads that are not being used.

  According to the invention of claim 6, each of the plurality of ink discharge head units has an ink discharge head that discharges the same color ink. Therefore, when an ink discharge failure occurs due to, for example, nozzle clogging in one ink discharge head unit, the other ink discharge head unit can make up for it.

According to the seventh aspect of the present invention, an image having a predetermined resolution can be formed even when there is a defective ink discharge head.
For example, in the case of having two ink ejection head units, if each unit is a 300 dpi unit of red, green, blue, yellow, magenta, and cyan (RGBYMC), the two are 600 dpi. In this case, when a discharge failure occurs due to, for example, nozzle clogging in one ink discharge head unit, the other ink discharge head unit is scanned a plurality of times and the ink is discharged by moving the pitch according to the insufficient resolution. Good. For example, when the second unit becomes a problem, after the first scanning and ink ejection of the first unit, the ink is ejected based on the scanning data of the second unit with a shift of 42 μm (corresponding to a pitch of 600 dpi). A predetermined resolution can be obtained by scanning and ejecting ink at a pitch according to a resolution that is not present (300 dpi × 2 times = 600 dpi).
Conventionally, when a sudden ejection failure such as non-ejection (misfire) occurs, it is necessary to stop the ejection and maintain the head, and if it still does not return, it is necessary to replace the ink ejection head. The time was very long. According to the present invention, since it is covered with another ink discharge head unit, the image formation time (tact) is extended, but head maintenance and head replacement can be performed during that time, so that the production efficiency is higher than when the apparatus is completely stopped. Will be much better.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a schematic perspective view showing an example of an image forming apparatus according to the present invention. A glass substrate 18 is set on a suction plate 1 with a stripe direction indicated by 20. The suction plate 1 is a flat bed table installed on the transfer table 3.
Further, the discarding area 2 provided at the end portion of the suction plate 1 is used for discarding from each head, and has an effect of stabilizing discharge.
Next, two ink discharge head units are provided in 8 and 13, which are mounted on two gate-type stages (also referred to as gantry stages) of 10, 10 'and 11, 11', respectively, and are linear motors (not shown). Although scanning is performed in the x direction, in FIG. 1, the vehicle is saved in a maintenance station area (an area where the moving rail portions 9 and 19 are provided).
FIG. 3 is a top view showing a schematic device configuration of the image forming apparatus. When the ink discharge head units 8 and 13 are moved onto the substrate 18 and the substrate 18 is scanned in the y direction, precise ink is discharged in synchronization with the encoder signal of the transport system. The scanning speed can be set to 100 mm / sec, for example, and the acceleration / deceleration can be set to 0.06 G, for example.

  The maintenance station has wiping units 4, 14 pressurizing / suction purge units 5, 15 cleaning units 6, 16 capping units 7, 17, which are moved on moving rails 9, 19 by a motor (not shown). Thus, a series of maintenance operations can be automatically performed.

  By the way, the ink discharge head unit has a scan width of 350 mm by connecting five sets of the ink discharge heads 12 (scanning width of about 72 mm, 180 dpi (360 dpi), 510 nozzles) as shown in FIG. . One ink discharge head unit is constituted by three colors, and two of the RGB ink discharge head unit 8 and the YMC ink discharge head unit 13 are shown in FIG. The plurality of ink discharge heads are adjusted in advance with a predetermined positional accuracy and aligned to constitute an ink discharge head unit.

When an image is formed on the substrate 18 from the ink discharge unit, the portal stage is subjected to load deformation due to the weight of the ink discharge head unit. The portal stage is provided with a deflection correcting means for correcting the relative positional accuracy error. Hereinafter, the deflection correction means will be described. The state in which the portal stage is bent is shown in FIGS.
The ink discharge head unit (weight is 200 kg / unit) is hung on the portal stage movable unit 23 which is a part of the portal stage. As shown in FIG. 6, the portal stage movable unit 23 is provided with an actuator 19 that can move up and down in the vertical direction (Z-axis direction) in units of μm. When the gap (gap) C between the glass substrate and the ink discharge head when the ink jet head unit is scanned at the gate type stage is bent to 0.4 mm (see FIG. 5) or less A mechanical stopper (limiter) is provided to prevent the head unit from being lowered. Usually, the gap C is held by a spring 21 with a gap of 1.0 mm or more. When scanning the ink discharge head unit, the actuator 19 is pressed in the downward direction according to the amount of deflection of the portal stage, and control is performed to maintain the gap C of 0.4 mm.

  The deflection correction unit is configured to perform tilt correction (tilt correction) in the Z direction as necessary. In order to perform tilt correction, the actuator has a structure having three or four points, and correction is made so that θ in FIG. 7 becomes zero.

  If an abnormal state occurs during ink ejection, for example, an emergency stop button is pressed, a servo error such as a motor is detected, or there is an abnormality in the glass substrate, etc., the gap sensor detects foreign matter or thickness defects. In such a case, or in the event of a power failure, the ink ejection head unit is released from the control in the downward direction and is raised by the preload of the spring 21. Therefore, the head of the ink discharge head unit does not interfere (contact) with the glass substrate or the like.

FIG. 4 is an explanatory diagram showing scanning and ink ejection procedures.
When the 730 mm direction of the 730 mm × 920 mm substrate 18 is scanned, image formation on one substrate is completed in one reciprocation except for a non-image forming area of about 30 mm on the outer periphery.

  In addition to this, if each unit in the development system is red, green, blue, yellow, magenta, cyan (RGBYMC) at 180 dpi, and this is set to 360 dpi by 2 units, there will be no ejection or mistake in one head unit. Even if problems such as direction (flight bending) and splash (ball cracking) occur, if the left side of the substrate 18 in FIG. 4 is scanned only once at 180 dpi, and the same operation is repeated on the right side of the substrate, the actual scanning is performed. Although the time is doubled, when the time for loading, unloading, and alignment of the substrate is taken into consideration, the tact time is actually increased by a factor of 1.5. If a stocker for the substrate is prepared, for example, even if the tact 120 seconds is increased to 180 seconds with the 20-sheet stocker, there is a grace period of up to 20 minutes. During that time, maintenance can be performed at the maintenance station and returned. I can do it.

  In the image forming apparatus and the image forming method of the present invention, a self-luminous image such as an organic EL can be formed in addition to the color filter. The substrate may be paper or film.

1 is a schematic perspective view illustrating an example of an image forming apparatus. FIG. 3 is an explanatory diagram illustrating an example of an arrangement of ink discharge heads in an ink discharge head unit. FIG. 2 is a top view illustrating a schematic device configuration of the image forming apparatus. Explanatory drawing which shows a scanning and an ink discharge procedure. Explanatory drawing which shows the bending of a portal type stage. FIG. 4 is an explanatory diagram illustrating a state in which the ink discharge head unit is viewed from the Y direction. FIG. 4 is an explanatory diagram showing an inclination of the ink discharge unit with respect to the Z direction due to bending of the portal stage.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Suction plate 2 ... Discarding area 3 ... Transfer table part (Y-axis)
4, 14 ... Wiping units 5, 15 ... Pressure purge (ink push-out) and suction purge (ink suction) units 6, 16 ... Ink discharge head cleaning units 7, 17 ... Capping unit 8 ... Ink ejection head unit (first unit)
9, 19... Moving rail portion 10, 10 '... First stage portal stage 11, 11'... Second unit portal stage 12... Ink ejection head 13. Head unit (second unit)
18 ... Substrate 19 ... Actuator 20 ... Stripe example 21 ... Spring 22 ... Horizontal part 23 ... Portal stage movable part C ... Clearance between glass substrate and ink ejection head

Claims (7)

In an image forming apparatus that forms an image by an ink ejection method,
A movable flat bed table on which a substrate on which the image is formed is placed;
A plurality of portal stages above the flat bed table;
An image forming apparatus comprising: a plurality of ink ejection head units that are independently provided and movable on each of the plurality of portal stages.   The image forming apparatus according to claim 1, wherein the portal stage includes a deflection correction unit.   The image forming apparatus according to claim 2, wherein the deflection correcting unit is provided independently for each of the plurality of portal stages.   The image forming apparatus according to claim 1, wherein the plurality of ink discharge head units are ink discharge head units that discharge different colors of ink.   5. The image formation according to claim 1, wherein the ink discharge head unit includes a plurality of ink discharge heads capable of discharging two or more colors in one ink discharge head unit. apparatus.   4. The image forming apparatus according to claim 1, wherein each of the plurality of ink discharge head units includes an ink discharge head that discharges ink of the same color. In an image forming method for forming an image by an ink ejection method,
Preparing to form an image of a predetermined resolution by a combination of ink ejection by a plurality of ink ejection head units;
Detecting a defect of any one of the plurality of ink discharge head units and stopping the use of the defective ink discharge head unit; and
And a step of discharging ink by combining at least one non-defective ink discharge head unit a required number of times and a movement for satisfying a predetermined resolution.

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