Head unit arrangement method, liquid droplet ejection apparatus, method of manufacturing electro-optic device, and electro-optic device

Provided herein is a head unit arrangement method for arranging a plurality of head units in a liquid droplet ejection device that plots an image in a matrix form with functional liquid droplets in a number n of colors by performing the number n of primary scans and a number (n−1) of secondary scans. The head unit arrangement method includes evaluating liquid droplet ejection performance of each of the head units based on an inspection result of a volume of liquid droplet ejection from each of the functional liquid droplet ejection heads to arrange two of the head units that exhibit the lowest liquid droplet ejection performance at both ends in the Y-axis direction.

The entire disclosure of Japanese Patent Application No. 2007-330800, filed Dec. 21, 2007, is expressly incorporated by reference herein.

BACKGROUND

1. Technical Field

The present invention relates to a head unit arrangement method for arranging a plurality of head units in alignment with a Y-axis direction in a liquid droplet ejection apparatus for plotting an image in a matrix form with functional liquid in a number n of colors, and a liquid droplet ejection apparatus, a method of manufacturing an electro-optic apparatus, and an electro-optic apparatus.

2. Related Art

Not using this kind of head unit arrangement method, a liquid droplet ejection apparatus equipped with a plurality of functional liquid droplet ejection heads for respective colors that are arranged in the form of a staircase, a plurality of carriage units arranged in alignment with a Y-axis direction, a set table on which a workpiece is set, an X-axis table that moves the set table in an X-axis direction, and a Y-axis table that moves a plurality of head units in the Y-axis direction has been known, as described in JP-A-2005-349381. In such a liquid droplet ejection apparatus, the plurality of functional liquid droplet ejection heads for respective colors are provided so as to form a plurality of partial plotting lines (divisional plotting lines) in respective colors; a plotting process is done by repeating a primary scan in which the respective functional liquid droplet ejection heads are driven synchronously with movement in the X-axis direction, and a secondary scan in which they are moved in the Y-axis direction by the length of a partial plotting line.

For such a liquid droplet ejection apparatus to achieve efficient plotting and to plot on workpieces of a plurality of sizes, a plurality of head units having aligned thereon a plurality of functional liquid droplet ejection heads are arranged to extend in a width direction and to cover the entire area of a workpiece. Accordingly, those of the plurality of functional liquid droplet ejection heads that are positioned at both ends are used less frequently; and those two head units positioned at both ends are used less frequently than those head units positioned in the intermediate portion between the above two head units. In plotting results produced on a workpiece, a central part stands out against both sides, which tends to result in visible color variation in the central part. Accordingly, the head units which are positioned in the intermediate portion and are adapted to plot on a central part of a workpiece tend to cause occurrence of color variation.

In the above liquid droplet ejection apparatus, however, a difference in frequency of use or occurrence of color variation among respective head units is not taken into consideration, which has caused the liquid droplet ejection apparatus to involve a problem that appropriate arrangement of head units cannot be done. For example, those of a plurality of head units that exhibit high performance may be arranged at both ends on which they are used less frequently and the degree of occurrence of color variation is low, which causes a problem that accurate plotting cannot be achieved.

SUMMARY

An advantage of some aspects of the invention is to provide a head unit arrangement method and a liquid droplet ejection apparatus that allow for appropriate arrangement of a plurality of head units and accurate, efficient plotting processes, a method of manufacturing an electro-optic apparatus and an electro-optic apparatus.

A head unit arrangement method according to one aspect of the invention is achieved by using a plurality of head units each having a carriage on which functional liquid droplet ejection heads for each of a number n of colors for forming a plurality of divisional plotted lines in each of the colors in the Y-axis direction by the respective nozzle rows are arranged to be staggered in the Y-axis direction. The method is achieved by further using a liquid droplet ejection apparatus that has the head units in a condition that they are arranged in alignment with the Y-axis direction and ejects functional liquid in the number n of colors to plot an image in a matrix form by performing a number n of primary scans for plotting by moving the head units relative to a workpiece in an X-axis direction and a number (n−1) of secondary scans by moving the head units by a space equivalent to the divisional plotted line relative thereto in the Y-axis direction. The head unit arrangement method for arranging the plurality of head units in alignment with the Y-axis direction in the liquid droplet ejection apparatus includes: (a) inspecting ejection volumes of liquid droplets by each of functional liquid droplet ejection heads, (b) evaluating a liquid droplet ejection performance of each of the heat units on the basis of the above inspection results, and (c) arranging two head units exhibiting the lowest liquid droplet ejection performance to both the ends in the Y-axis direction, respectively.

With this configuration, it is possible to arrange two head units exhibiting the lowest liquid droplet ejection performance at both ends of an alignment of multiple head units, thereby allocating the head units exhibiting lower liquid droplet ejection performance to both the ends on which they are used less frequently and the degree of occurrence of color variation is low. This allows arranging head units properly and using efficiently head units exhibiting higher liquid droplet ejection performance. This also allows preventing color variation, resulting in accurate plotting.

In this situation, it is preferable that the mounted functional liquid droplet ejection heads be ranked depending on whether they satisfy the following conditions: (A) a condition of a variation range under which the variation that is in the liquid droplet ejection volume among respective ejection nozzles on a nozzle row and is obtained through inspection, is within a prescribed variation range; and (B) a condition of an intercept range under which differences between the average of the liquid droplet ejection volumes among the respective ejection nozzles in which the volumes are obtained through inspection and two liquid droplet ejection volumes of two ejection nozzles located at both ends of the nozzle row, are within a prescribed permissible range. It is also preferable that the head units be evaluated on the basis of the ranks given to the respective functional liquid droplet ejection heads in evaluation of the liquid droplet ejection performance of the head units.

With this configuration, the respective functional liquid droplet ejection heads are ranked using the above conditions of the variation range and intercept range, and then the head units are evaluated on the basis of the respective ranks, which allows evaluating the head units accurately and properly. The use of the ranks may facilitate comparison of the respective functional liquid droplet ejection heads.

In this situation, it is preferable that the lowest of the ranks given to the mounted functional liquid droplet ejection heads be used as an evaluation of each of the head units in evaluation of the liquid droplet ejection performance of the head unit.

With this configuration, the lowest of the ranks given to the respective functional liquid droplet ejection heads that is closely connected to occurrence of color variation is used as an evaluation of the liquid droplet ejection performance of the head unit, which allows evaluating the liquid droplet ejection performance of the head units properly and accurately. The head units are evaluated by the lowest rank, which allows comparing the respective head units easily.

In this situation, it is preferable that the evenness in the liquid droplet ejection volume between head units be evaluated on the basis of the difference in the liquid droplet ejection volume between nearest ejection nozzles for each color which are on different adjacent head units; it is also preferable that the respective head units except the two positioned at both ends be arranged so that a combination thereof may exhibit the greatest evenness in the liquid droplet ejection volume.

With this configuration, it is possible to evaluate the evenness in the liquid droplet ejection volume between head units based on the difference in the liquid droplet ejection volume between nearest ejection nozzles for each color which are on different adjacent head units, arrange the respective head units so that a combination thereof may exhibit the greatest evenness in the liquid droplet ejection volume, thereby diminishing a difference in the liquid droplet ejection volume between head units. This allows preventing color variation and streaking, resulting in more accurate plotting.

In this situation, it is preferable that the evenness in the liquid droplet ejection volume be evaluated on the basis of the maximum among the differences in the liquid droplet ejection volumes obtained for all colors at all boundaries between head units in evaluation of the evenness in the liquid droplet ejection volume between head units.

With this configuration, it is possible to evaluate accurately and properly the evenness in the liquid droplet ejection volume based on the maximum among the differences in the liquid droplet ejection volume obtained for all colors at all boundaries.

In this situation, it is preferable that the liquid droplet ejection volumes of two ejection nozzles used to calculate the difference in the liquid droplet ejection volume be average values among liquid droplet ejection volumes of two or more ejection nozzles located at respective adjacent ends.

With this configuration, it is possible to diminish the variation in the liquid droplet ejection volume, the variation occurring on one of the above two ejection nozzles. This allows calculating a combination satisfying the above conditions accurately.

In this situation, a plurality of head units are selected from numerous candidate head units that are candidates for mounting; it is preferable that a plurality of head units exhibiting the highest liquid droplet ejection performance be selected from the numerous candidate head units in selection of the plurality of head units.

With this configuration, more accurate plotting may be achieved by selecting for use head units exhibiting higher liquid droplet ejection performance from numerous candidate head units that are candidates for mounting.

The liquid droplet ejection apparatus according to another aspect of the invention includes a plurality of head units arranged by the above head unit arrangement method and an X-Y movement mechanism that moves a workpiece relatively to the head units in X- and Y-axis directions.

With this configuration, it is possible to improve the yield of a workpiece by using the head unit arrangement method which method allows for accurate plotting.

In this situation, the X-Y movement mechanism is configured so that each of the plurality of head units is independently movable.

With this configuration, each head unit is configured to be independently movable, which allows performing a plotting or maintenance operation by each individual head unit.

A method for manufacturing an electro-optic apparatus according to a further aspect of the invention features to provide a film formed portion on a workpiece by functional liquid droplets by using the above liquid droplet ejection apparatus.

An electro-optic apparatus according to a still further aspect of the invention features to have a film formed portion which is formed on a workpiece by functional liquid droplets by using the above liquid droplet ejection apparatus.

With this configuration, it is possible to manufacture electro-optic apparatuses with high quality efficiently. Functional materials include a light-emitting material for an organic electroluminescence (EL) apparatus (i.e., electroluminescent layer, positive hole injection layer), a filter material (filter element) for a color filter used in a liquid crystal display, a fluorescent material (phosphor) for a field emission display (FED), a fluorescent material (phosphor) for a plasma display panel (PDP) apparatus, and an electrophoretic material (electrophoretic substance) for an electrophoretic display, the materials being liquid materials ejectable by functional liquid droplet ejection heads (inkjet heads). Electro-optic apparatuses (flat panel displays or FPDs) include an organic EL apparatus, a liquid crystal display, a field emission display apparatus, a plasma display panel apparatus (PDP apparatus) and an electrophoretic display.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

A liquid droplet ejection apparatus to which a head unit arrangement method according to an embodiment of the invention is applied will be described hereinafter with reference to the accompanying drawings. A liquid droplet ejection apparatus according to the embodiment is incorporated into a production line of a flat panel display; it uses its functional liquid droplet ejection head to which functional liquid, e.g., a special ink or luminous resin liquid is introduced to form luminous elements that constitute pixels included in a color filter of a liquid crystal display or in an organic EL apparatus.

As shown inFIGS. 1 and 2, a liquid droplet ejection apparatus1includes an X-axis table11that is set up on an X-axis support base2supported by a stone surface plate to extend in an X-axis direction that is a primary scan direction, moving a workpiece W in the X-axis direction (primary scan direction), a Y-axis table12that is set up on a pair of (or two) Y-axis support bases3extending to cross over the X-axis table11with the assistance of a plurality of poles4, extending in a Y-axis direction that is a secondary scan direction, and ten carriage units51each having mounted thereon a plurality of functional liquid droplet ejection heads17, the ten carriage units51hung from the Y-axis table12in alignment with the Y-axis direction. Synchronized with movements of the X-axis table11and Y-axis table12, the functional liquid droplet ejection heads17are driven for ejection; whereby functional liquid droplets in RGB, three colors are ejected, and then a prescribed plotting pattern is plotted on the workpiece W. The X-Y movement mechanism described in the appended claims is formed of the X-axis table11and Y-axis table12.

The liquid droplet ejection apparatus1also includes a maintenance device5configured of a flushing unit14, a suction unit15, a wiping unit16and an ejection performance check unit18, providing those units for maintenance of the functional liquid droplet ejection heads17to perform functional maintenance and restoration for the functional liquid droplet ejection heads17. Among the units constituting the maintenance device5, the flushing unit14and ejection performance check unit18are mounted on the X-axis table11, and the suction unit15and wiping unit16are set up on a pedestal6disposed on a position that is out of the area of the X-axis table11and is within the movable area of the carriage units51moved by the Y-axis table12. (To be exact, the ejection performance check unit18includes a stage unit77mounted on the X-axis table11and a camera unit78supported on the Y-axis support base3, the configuration of the above units being described below.)

The flushing unit14includes a pair of pre-plotting flushing units111and a periodic flushing unit112, serving to receive droplets ejected for discarding (or flushing) from the functional liquid droplet ejection heads17, the discarding being carried out immediately before ejection from the functional liquid droplet ejection heads17or in an intermission between plotting processes for replacement of the workpiece W or other operations. The suction unit15includes a plurality of divisional suction units141, exerting forced suction on functional liquid from ejection nozzles98on the functional liquid droplet ejection heads17. The wiping unit16includes wiping sheets151for wiping off a nozzle face97of each of the functional liquid droplet ejection heads17after the suction. The ejection performance check unit18includes a stage unit77having mounted thereon a check sheet83for receiving functional liquid droplets ejected from the functional liquid droplet ejection heads17, and a camera unit78for checking the functional liquid droplets on the stage unit77through image recognition; it serves to check the ejection performance of the functional liquid droplet ejection heads17(whether functional liquid is ejected and whether the ejected functional liquid is deviated).

Components constituting the liquid droplet ejection apparatus1will be described hereinafter. As shown inFIGS. 1 and 2, the X-axis table11includes a set table21on which the workpiece W is to be set, a first X-axis slider22that supports the set table21so as to be slidable in the X-axis direction, a second X-axis slider23that supports the above flushing unit14and ejection performance check unit18so as to be slidable in the X-axis direction, a pair of right and left X-axis linear motors (not shown) which are extending in the X-axis direction, move the set table21(or workpiece W) in the X-axis direction with the assistance of the first X-axis slider22and also move the flushing unit14and stage unit77in the X-axis direction with the assistance of the second X-axis slider23, and a pair of (or two) X-axis common support bases24arranged in parallel with the X-axis linear motors so as to guide the movements of the first and second X-axis sliders22and23.

The set table21includes an adhesive table31on which the workpiece W is adhesively set, a θ table32for correcting in the θ-axis direction the position of the workpiece W that is set on the adhesive table31, and the like. The above pre-plotting flushing units111are attached respectively to a pair of sides of the set table21the sides being in parallel with the Y-axis direction.

The Y-axis table12includes ten bridge plates52from which the ten carriage units51are hung respectively, ten pairs of Y-axis sliders (not shown) that support the ten bridge plates52at both ends, respectively, a pair of Y-axis linear motors (not shown) which are provided on the above pair of Y-axis support bases3and move the bridge plates52in the Y-axis direction with the assistance of ten pairs of Y-axis sliders. The Y-axis table12allows the functional liquid droplet ejection heads17to carry out a secondary scan through the respective carriage units51during plotting and to face the maintenance device5.

With the pair of Y-axis linear motors (synchronously) driven, the respective Y-axis sliders are guided by the pair of Y-axis support bases3and moved in parallel simultaneously. The bridge plates52are thus moved in the Y-axis direction, and then the carriage units51are moved therewith in the Y-axis direction. In this situation, the respective carriage units51may be independently and individually moved, or the ten carriage units51may be moved as one unit by controlling the drive of the Y-axis linear motors. Thus, each of the ten carriage units51(or each of the head units13) is configured so as to be independently and individually movable, which allows each of the carriage units51to be used for plotting and to be maintained individually.

Each of the carriage units51includes a head unit13that has a plurality of functional liquid droplet ejection heads17, a θ-rotation mechanism61that supports the head unit13in such a manner that allows for θ-correction (θ-rotation) of the head unit13, and a hanging member62that has the Y-axis table12(or each of the bridge plates52) support the head unit13with the θ-rotation mechanism61therebetween.

As shown inFIGS. 2 and 3, the head unit13includes twelve functional liquid droplet ejection heads17and a carriage plate (carriage)53on which the twelve functional liquid droplet ejection heads17are arranged and secured. The twelve functional liquid droplet ejection heads17are divided into two groups in the Y-axis direction; the six functional liquid droplet ejection heads in each of the head groups54are arranged in the form of a staircase in the X-axis direction, constituting a head group54. The six functional liquid droplet ejection heads17belonging to each head group54are arranged to be staggered from one another in the direction of a nozzle row99b. This configuration allows arranging a plurality of functional liquid droplet ejection heads17on the carriage plate53efficiently and also allows for efficient plotting processes.

Each of ten times the twelve functional liquid droplet ejection heads17mounted on a head unit13corresponds to any of the RGB, three colors; with four functional liquid droplet ejection heads17for each color (two for each color in each head group54), it is possible to plot a plurality of divisional plotted lines in respective colors on the workpiece W. The functional liquid droplet ejection heads17are cyclically arranged in RGB order from left to right. With the assistance of two times of secondary scans by all the (or ten times twelve) functional liquid droplet ejection heads17, plotted lines in the RGB, three colors continuous in the Y-axis direction are formed respectively such that each of the plotted lines is constituted of a plurality of divisional plotted lines in each of the RGB, three colors. This means that there are spaces equivalent to two divisional plotted lines in length in the Y-axis direction between two functional liquid droplet ejection heads17for each color included in one head group54and two functional liquid droplet ejection heads17for the same color included in the other head group54on a head unit13, respectively. There is also a space equivalent to two divisional plotted lines in length in the Y-axis direction between adjacent head groups54that are mounted on different head units13. The length of a plotted line may be up to the width of a workpiece W in the maximum size that is mountable on the set table21.

An arrangement configuration of twelve functional liquid droplet ejection heads17on the carriage plate53may be changed for convenience as long as each of the functional liquid droplet ejection heads17to be mounted on the carriage plate53has a plurality of nozzles98that are capable of forming a plurality of divisional plotted lines in respective colors, the divisional plotted lines being staggered in the Y-axis direction. For example, the twelve functional liquid droplet ejection heads17may be arranged in the form of a staircase without being divided into two head groups54. Naturally, the number of functional liquid droplet ejection heads17mounted on each carriage unit51may be determined for convenience.

As shown inFIG. 4, the functional liquid droplet ejection head17is a so-called twin inkjet head, including a functional liquid introducer91having a pair of connection needles92, a twin head substrate93coupled to the functional liquid introducer91, and a head body94having formed therein intrahead channels which are communicating with the lower part of the functional liquid introducer91and filled with functional liquid. The connection needles92are connected to a functional liquid tank that is not shown in the drawing, and then the connection needles92supply functional liquid to the functional liquid introducer91. The head body94is formed of a cavity95(piezoelectric element) and a nozzle plate96having a nozzle face97on which a number of ejection nozzles98are opened. When the functional liquid droplet ejection head17is driven for ejection, (a voltage is applied to the piezoelectric element and) functional liquid droplets are ejected from the ejection nozzles98by the pumping action of the cavity95.

First and second nozzle rows99aand99beach configured of numerous ejection nozzles98are formed in parallel with one another on the nozzle face97. The two nozzle rows99aand99bare staggered from each other by a half nozzle pitch. Each of the two nozzle rows99aand99bhas ten inoperative nozzles at both respective ends, which are not used for plotting processes, whereby it is possible to suppress the variation in liquid droplet ejection volume on the nozzle rows99aand99band to perform the plotting processes with higher quality. The “nozzle row” described in the appended claims means the combination of the first and second nozzle rows99aand99baccording to the embodiment. The first and second nozzle rows99aand99b, therefore, are combined into one set to be referred to as nozzle row99hereinafter.

Plotting operations by the liquid droplet ejection apparatus1will be described hereinafter. These operations are performed with each of carriage units51arranged in alignment with the Y-axis direction. First, in the operations of the liquid droplet ejection apparatus1, a first plotting operation (on the forward path) is performed while the workpiece W is moved by the X-axis table11(to the back side inFIG. 1) in the X-axis direction. Next, after the head units13are moved by a space equivalent to two heads (a divisional plotted line) in the Y-axis direction (which movement is a secondary scan), a second plotting operation (on the backward path) is performed while the workpiece W is moved (to the front side inFIG. 1) in the X-axis direction. Lastly, after the secondary scan of the head units13is carried out by a space equivalent to two heads (a divisional plotted line), a third plotting operation (on the forward path) is performed while the workpiece W is moved (to the back side inFIG. 1) in the X-axis direction again. Thus, the functional liquid droplet ejection heads17corresponding to a position on the workpiece W are changed through three primary scans and two secondary scans while movements of and plotting operations on the workpiece W are repeated; whereby an image is plotted with functional liquid in the RGB, three colors in a matrix form according to a prescribed pattern. As shown inFIGS. 5A to 5C, there are three kinds of plotting patterns that are made with functional liquid in three colors; the plotting pattern (bitmap data) shown inFIG. 5Ais used for plotting in the embodiment.

Since the ten carriage units51carry out plotting processes with functional liquid in three colors through three primary scans and two secondary scans, ten times twelve functional liquid droplet ejection heads17mounted on ten carriage units51are arranged to be extended beyond the edges of the workpiece W in its width direction. More specifically, in a primary position (or the first plotting operation), some right ejection nozzles of the functional liquid droplet ejection heads17for the G and B colors mounted on the right side of the carriage unit51that is disposed on the right side in the ten carriage units51are located out of the pixel area in the Y-axis direction. In a position taken after the two times of secondary scans (or the third plotting operation), some left ejection nozzles of the functional liquid droplet ejection heads17for the R and G colors mounted on the left side of the carriage unit51that is disposed on the left side in the ten carriage units51are located out of the pixel area in the Y-axis direction. Thus, these functional liquid droplet ejection heads17are used less frequently than the other functional liquid droplet ejection heads17so that the head units13positioned on both the outer ends are used less frequently.

A method of selecting and arranging functional liquid droplet ejection heads17and a method of selecting and arranging carriage units51will be described in detail hereinafter with reference toFIGS. 6 to 10.FIG. 6is a flow chart concerning operations of selecting and arranging functional liquid droplet ejection heads17. In selection of functional liquid droplet ejection heads17, the functional liquid droplet ejection heads17for respective colors to be mounted on carriage plates53are selected from numerous candidate heads that have been manufactured. In the following description, inoperative ejection nozzles that are not involved in plotting or measuring will be ignored.

As shown inFIG. 6, numerous candidate heads are classified by the colors, firstly (S1). When, for example, 300 candidate heads are manufactured, 100 candidate heads are assigned to each of the RGB, three colors. Next, the candidate heads are inspected by each color, respectively (S2).

Inspection of respective candidate heads is conducted by an inspection device that is not shown in the drawing. The inspection device detects a liquid droplet ejection volume, an ejection speed, an ejection failure and other characteristics of each ejection nozzle98of each candidate head. Especially, the liquid droplet ejection volume of each of all ten ejection nozzles98located at both respective ends is measured; that of each of the other ejection nozzles98(the plurality of ejection nozzles98located in the intermediate portion) is obtained using a approximation property line graph (shown inFIG. 7) based on the measurements of the ejection nozzles98located at both ends. Measurements of the liquid droplet ejection volume of ejection nozzles98located at both respective ends are performed in such a manner that landed liquid droplets are formed by ejecting four to six shots from the ejection nozzle98onto a water-repellent surface, and are dried for measuring the volume thereof by white-light interferometer or any other instrument. The liquid droplet ejection volume may be measured in such a manner that the weight of the landed liquid droplets may be measured by electronic force balance, or the volume thereof may be calculated based on image recognition results that are obtained by using an image recognition camera facing downward and/or sideward to the landed liquid droplets. As a line graph of approximation properties, a line graph of sixth-order approximation properties can be used. The above ejection failures include no ejection, deflection and abnormal ejection.

To facilitate the following comparison and calculation, the value of the obtained liquid droplet ejection volume is referred to as a percentage of an increment or decrement to a reference value with the reference value deemed 100%. For example, when the reference value is 1.05 pl and the liquid droplet ejection volume is 1.0605 pl, the value thereof is +1%, which is obtained from the following expression: 1.0605=1.05+(1.05×0.01)=1.05+(1.05×1%); when the liquid droplet ejection volume is 1.0395 pl, the value thereof is −1%, which is obtained from the following equation: 1.0395=1.05−(1.05×0.01)=1.05−(1.05×1%).

Next, the variation in and the intercepts of the liquid droplet ejection volume are obtained from the detected liquid droplet ejection volumes of the respective ejection nozzles98(S3and S4). The variation in the liquid droplet ejection volume is a difference between the maximum and minimum of the liquid droplet ejection volume among all the ejection nozzles98. The intercepts are differences between the liquid droplet ejection volumes of two ejection nozzles98located at both the ends of the nozzle row99and the average of the liquid droplet ejection volume among all the ejection nozzles98. This means that two intercepts of the liquid droplet ejection volume are obtained at the right and left ends. Since the average of the liquid droplet ejection volume among all the ejection nozzles98is equal to the above reference value, the intercepts are equal to the liquid droplet ejection volumes of the ejection nozzles98located at both ends. The intercept does not take an absolute value; it is obtained with a plus or minus symbol attached thereto. As a liquid droplet ejection volume which is each of the two ejection nozzles98and is used to obtain the intercept, the average value of the liquid droplet ejection volumes of ten ejection nozzles98located at respective both the ends may be preferably used. Consequently, it is possible to diminish the variation in the liquid droplet ejection volume of one ejection nozzle98and to accurately perform the comparison and calculation concerning the intercept which will be described below.

When the variation in the liquid droplet ejection volume and the intercepts thereof at both the ends are obtained, each of the candidate heads is given a rank of S, A or B and defective heads are eliminated depending on the obtained result (S5). The ranking of each candidate head is given depending on whether conditions of a variation range and intercept range are satisfied. The condition of the variation range is a condition under which the variation in the liquid droplet ejection volume is within the variation range set for each rank, and the condition of the intercept range is a condition under which the absolute value of each of the intercepts of the liquid droplet ejection volume is within the permissible range set for each rank. For the rank S, the variation range is set at 2% or below; the permissible range of the intercept is set at 0.65% or below. In other words, a candidate head whose variation is 2% or below and the absolute value of each of whose intercepts is 0.65% or below is given the rank S. For the rank A, the variation range is set at 2.5% or below; the permissible range of the intercept is set at 0.9% or below. For the rank B, the variation range is set at 3% or below; the permissible range of the intercept is set at ∞% (or is not limited).

Candidate heads that are not given any of the ranks S, A or B (or whose variation is over 3%) and candidate heads in which ejection failure is detected by the above inspection are eliminated as defective heads. When, for example, 20 of 100 candidate heads assigned to the color B are given the rank S, 40 thereof are given the rank A, and 30 thereof are given the rank B, 10 thereof are identified as defective heads. In this situation, the 10 candidate heads are eliminated as defective heads, and then each of the 90 candidate heads is left as the head with its rank. The rank that is thus given is obtained as a liquid droplet ejection volume property of each candidate head.

Next, a plurality of functional liquid droplet ejection heads17to be mounted on the carriage units51are selected from the candidate heads depending on the ranks (liquid droplet ejection volume properties) (S6). Selection of functional liquid droplet ejection heads17is made by selection criteria that are set depending on a correlation between the liquid droplet ejection volume property (rank) of a candidate head and the degree of occurrence of color variation in each color. More specifically, since color variation occurs more frequently to the B color, ranks acceptable to the B color are the ranks S and A, and ranks acceptable to the R and G colors are all the ranks. For the B color, candidate heads with the rank S or A are selected as functional liquid droplet ejection heads17to be mounted. At this moment, candidate heads that do not satisfy the selection criteria (acceptable ranks) are eliminated. The candidate heads that have been eliminated may be used as candidate heads for other colors. As the correlation between the liquid droplet ejection volume property and the degree of occurrence of color variation in each color described herein, a correlation between the liquid droplet ejection volume property of a candidate head (functional liquid droplet ejection head17) and the degree of occurrence of visible color variation in each color in a finished product which is obtained by experiment, is used. This means that data of the correlation is varied depending on the finished product to be used, so that the selection criteria are not limited to the above selection criteria.

When functional liquid droplet ejection heads17are selected for each color, the functional liquid droplet ejection heads17are arranged and mounted on respective carriage units51(S7). The respective carriage units51described herein are not the ten carriage units51to be mounted on the apparatus, but numerous candidate carriage units that are subject to selection of ten carriage units51. The candidate head units described in the appended claims are head units13mounted on the candidate carriage units; to be exact, they are to be equipped with functional liquid droplet ejection heads17for respective colors.

As well as the carriage units51, each candidate carriage unit is equipped with four functional liquid droplet ejection heads17for each color: twelve totally. At this moment, the respective functional liquid droplet ejection heads17are arranged in positions determined for respective colors (as shown inFIG. 3); candidate carriage units for any color are arranged and mounted on candidate carriage units having the same rank on a candidate carriage unit irrespective of the colors. For example, functional liquid droplet ejection heads17for respective colors having a high rank are mounted on the same candidate carriage units; functional liquid droplet ejection heads17for respective colors having a low rank are mounted on the same candidate carriage units. When the respective functional liquid droplet ejection heads17are mounted on the candidate carriage units, the ejection property information (rank, variation and intercepts) of each of the functional liquid droplet ejection heads17is packed as information for the candidate carriage unit equipped therewith.

Next, a method of selecting and arranging ten carriage units51will be described hereinafter with reference toFIGS. 8 and 9. Through the following operations of selecting and arranging carriage units51, head units13to be mounted on the carriage units51are selected and arranged.FIG. 8is a flow chart concerning operations of selecting and arranging carriage units51. As shown inFIG. 8, ranking is given to respective candidate carriage units (S11). Ranking is given using the ranks included in the ejection performance information of respective functional liquid droplet ejection heads17, the information being packed in respective candidate carriage units. This means that a rank given to each candidate carriage unit is set at the lowest rank (S>A>B) given to the functional liquid droplet ejection heads17mounted thereon. Thus, a rank S, A or B is given to each candidate carriage unit.

When a rank is given, ten carriage units51are selected from numerous candidate carriage units based on the rank. Ten of all candidate carriage units having the highest ranks are selected as ten carriage units51to be mounted on the liquid droplet ejection apparatus1. When carriage units51tenth and eleventh ranks from highest to lowest are the same, they are ranked in descending order by accuracy using the variation and intercepts of each mounted functional liquid droplet ejection head17to select a carriage unit51having the higher rank (or higher accuracy). More accurate plotting may be achieved by selecting for use carriage units51(head units13) exhibiting higher liquid droplet ejection performance (ranks) from numerous candidate carriage units (candidate head units) that are candidates for mounting.

Next, (the order of) arrangement of the ten selected carriage units51is determined. The ten carriage units51are arranged in alignment with the Y-axis direction; two of the ten carriage units51that have the lowest rank are arranged at both ends first, as shown inFIG. 9(S13). Thus, two carriage units51(head units13) exhibiting the lowest liquid droplet ejection performance (rank) are arranged at both ends; whereby carriage units51exhibiting lower liquid droplet ejection performance are allocated to both ends at which they are used less frequently and the degree of occurrence of color variation is low. This allows arranging carriage units51properly and using efficiently carriage units51exhibiting higher liquid droplet ejection performance. This also allows preventing color variation, resulting in accurate plotting.

Ranking is given to respective functional liquid droplet ejection heads17using the conditions of the variation range and intercept range; carriage units51(head units13) are evaluated on the basis of their ranks, which allows evaluating carriage units51accurately and properly. The use of ranks facilitates comparison of respective functional liquid droplet ejection heads17.

The lowest of the ranks given to respective functional liquid droplet ejection heads17that is closely connected to occurrence of color variation is evaluated as liquid droplet ejection performance, which allows evaluating the liquid droplet ejection performance of a carriage unit51(head unit13) properly and accurately. Carriage units51are evaluated by the lowest rank, which allows comparing respective carriage units easily.

Next, (the order of) arrangement of the other eight carriage units51excluding two positioned at both ends is determined as follows. When ten positions of the ten carriage units51are respectively referred to as A1, A2, through A10, the difference between the intercepts of carriage units51located at seven boundaries between A2and A3, A3and A4, A4and A5, A5and A6, A6and A7, A7and A8, and A8and A9in the order (pattern) of arrangement of the eight carriage units51is calculated.

When two head units13located at a boundary are referred to as left and right head units, and twelve functional liquid droplet ejection heads17mounted on each head unit13are referred to as a head1, a head2, through a head12from left to right, the difference between the intercepts obtained at each boundary is calculated from the intercepts obtained at the right end of the functional liquid droplet ejection heads17for respective colors which are positioned at the right end on the left head unit (head10for R color, head11for G color and head12for B color), and the intercepts obtained at the left end of the functional liquid droplet ejection heads17for respective colors which are positioned at the left end on the right head unit (head1for R color, head2for G color and head3for B color). This means that with a difference between two intercepts (an intercept difference) obtained for each color, the largest of the three intercept differences obtained for the RGB, three colors is used as an intercept difference. When the intercepts obtained at the right end of the heads10,11and12mounted on the left head unit are +0.52%, +0.31% and −0.64% and the intercepts obtained at the left end of the heads1,2, and3mounted on the right head unit are +0.07%, +0.55% and −0.33%, for example, the intercept differences obtained for respective colors are: (R, G, B)=(0.45%, 0.24%, 0.31%). The largest of the values that is 0.45% for the color R is referred to as an intercept difference at the boundary.

Next, the evenness in the liquid droplet ejection volume between carriage units51in each type of arrangement order is evaluated using the intercept differences at the respective boundaries. The evenness in the liquid droplet ejection volume is the degree of difference in the liquid droplet ejection volume between head units13. It is highly evaluated when the maximum among the intercept differences obtained at the seven boundaries is small, while it is lowly evaluated when the maximum among the intercept differences obtained at the seven boundaries is great. One of all the types of arrangement order that has the most-highly evaluated evenness is selected as arrangement of eight carriage units51to be positioned in the intermediate portion. In other words, the arrangement order having the smallest maximum among the intercept differences at the seven boundaries is selected as arrangement of carriage units51to be positioned in the intermediate portion (S14). According to the selected arrangement, ten carriage units51are mounted on (the Y-axis table12of) the liquid droplet ejection apparatus1(S15). In the embodiment, the maximum of the intercepts calculated for respective colors at each boundary is obtained, and the maximum value among the maximums obtained at the respective boundary is used for evaluation of the evenness in the liquid droplet ejection volume; as shown inFIG. 10, however, it is possible to obtain for each color the maximum among the intercepts at respective boundaries and use the maximum value among the three maximums obtained for the respective colors for evaluation of the evenness in the liquid droplet ejection volume.

Thus, it is possible to evaluate the evenness in the liquid droplet ejection volume between carriage units51(head units13) based on the difference in the liquid droplet ejection volume between nearest ejection nozzles98for each color disposed on different adjacent head units, arrange respective carriage units51so that a combination thereof may exhibit the greatest evenness in the liquid droplet ejection volume, thereby diminishing differences in the liquid droplet ejection volume among the carriage units51. This allows preventing color variation and streaking, resulting in more accurate plotting.

It is also possible to evaluate accurately and properly the evenness in the liquid droplet ejection volume based on the maximum among the differences in the liquid droplet ejection volume obtained for all colors at all seven boundaries (the number of which differences is seven times three).

With the above configuration, it is possible to arrange two head units13exhibiting the lowest liquid droplet ejection performance at both ends of an alignment of multiple head units13, thereby allocating the head units13exhibiting lower liquid droplet ejection performance to both the ends at which they are used less frequently and so does color variation occur. This allows arranging head units13properly and using efficiently head units13exhibiting higher liquid droplet ejection performance. This also allows preventing color variation, resulting in accurate plotting.

It is also possible to improve the yield of a workpiece W by using the method of arranging head units13which the method allows for accurate plotting.

As the method of arranging the carriage units51(head units13), (a) the carriage units51with respective lower ranks are arranged at both ends, and (b) carriage units51in a combination which may exhibit the great evenness in the liquid droplet ejection volume are arranged to be positioned in the intermediate portion; however, the carriage units51may be arranged under only any one of the above conditions (a) and (b).

In the embodiment, selection and arrangement are performed by a unit of a carriage unit51; however, it may be performed by a unit of a head unit13.

The liquid droplet ejection apparatus1according to the embodiment includes ten carriage units51; however the number of carriage units51may be determined for convenience.

In the embodiment, while the invention is applied to the functional liquid droplet ejection apparatus1using functional liquid in RGB (red, green and blue), three colors; the number of colors and types of functional liquid are not limited thereto. For example, the invention may be applied to an apparatus using functional liquid in CMY (cyan, magenta and yellow), three colors or in RGB and CMY, six colors. When functional liquid in six (or a number n of) colors is used, plotting on a workpiece with functional liquid in six (or the number n of) colors is performed through six (or the number n of) primary scans and five (or a number [n−1] of) secondary scans.

Taking electro-optical apparatuses (flat panel display apparatuses) manufactured using the liquid droplet ejection apparatus1and active matrix substrates formed on the electro-optical apparatuses as display apparatuses as examples, configurations and manufacturing methods thereof will now be described. Examples of the electro-optical apparatuses include a color filter, a liquid crystal display apparatus, an organic EL apparatus, a plasma display apparatus (PDP (plasma display panel) apparatus), and an electron emission apparatus (FED (field emission display) apparatus and SED (surface-conduction electron emitter display) apparatus). Note that the active matrix substrate includes thin-film transistors, source lines and data lines which are electrically connected to the thin film transistors.

First, a manufacturing method of a color filter incorporated in a liquid crystal display apparatus or an organic EL apparatus will be described.FIG. 11shows a flowchart illustrating manufacturing steps of a color filter.FIGS. 12A to 12Eare sectional views of the color filter500(a filter substrate500A) of this embodiment shown in an order of the manufacturing steps.

In a black matrix forming step (step S101), as shown inFIG. 12A, a black matrix502is formed on the substrate (W)501. The black matrix502is formed of a chromium metal, a laminated body of a chromium metal and a chromium oxide, or a resin black, for example. The black matrix502may be formed of a thin metal film by a sputtering method or a vapor deposition method. Alternatively, the black matrix502may be formed of a thin resin film by a gravure plotting method, a photoresist method, or a thermal transfer method.

In a bank forming step (step S102), the bank503is formed so as to be superposed on the black matrix502. Specifically, as shown inFIG. 12B, a resist layer504which is formed of a transparent negative photosensitive resin is formed so as to cover the substrate501and the black matrix502. An upper surface of the resist layer504is covered with a mask film505formed in a matrix pattern. In this state, exposure processing is performed.

Furthermore, as shown inFIG. 12C, the resist layer504is patterned by performing etching processing on portions of the resist layer504which are not exposed, and the bank503is thus formed. Note that when the black matrix502is formed of a resin black, the black matrix502also serves as a bank.

The bank503and the black matrix502disposed beneath the bank503serve as a partition wall507bfor partitioning the pixel areas507a. The partition wall507bdefines receiving areas for receiving the functional liquid ejected when the functional liquid droplet ejection heads17form coloring layers (film portions)508R,508G, and508B in a subsequent coloring layer forming step.

The filter substrate500A is obtained through the black matrix forming step and the bank forming step.

Note that, in this embodiment, a resin material having a lyophobic (hydrophobic) film surface is used as a material of the bank503. Since a surface of the substrate (glass substrate)501is lyophilic (hydrophilic), variation of positions to which the liquid droplet is projected in the each of the pixel areas507asurrounded by the bank503(partition wall507b) can be automatically corrected in the subsequent coloring layer forming step.

In the coloring layer forming step (S103), as shown inFIG. 12D, the functional liquid droplet ejection heads17eject the functional liquid within the pixel areas507aeach of which are surrounded by the partition wall507b. In this case, the functional liquid droplet ejection heads17eject functional liquid droplets using functional liquid (filter materials) of colors R, G, and B. A color scheme pattern of the three colors R, G, and B may be the stripe arrangement, the mosaic arrangement, or the delta arrangement.

Then drying processing (such as heat treatment) is performed so that the three color functional liquid are fixed, and thus three coloring layers508R,508G, and508B are formed. Thereafter, a protective film forming step is reached (step S104). As shown inFIG. 12E, a protective film509is formed so as to cover surfaces of the substrate501, the partition wall507b, and the three coloring layers508R,508G, and508B.

That is, after liquid used for the protective film is ejected onto the entire surface of the substrate501on which the coloring layers508R,508G, and508B are formed and the drying process is performed, the protective film509is formed.

In the manufacturing method of the color filter500, after the protective film509is formed, a coating step is performed in which ITO (Indium Tin Oxide) serving as a transparent electrode in the subsequent step is coated.

FIG. 13is a sectional view of an essential part of a passive matrix liquid crystal display device (liquid crystal display device520) and schematically illustrates a configuration thereof as an example of a liquid crystal display device employing the color filter500. A transmissive liquid crystal display device as a final product can be obtained by disposing a liquid crystal driving IC (integrated circuit), a backlight, and additional components such as supporting members on the display device520. Note that the color filter500is the same as that shown inFIGS. 12A to 12E, and therefore, reference numerals the same as those used inFIGS. 6A to 6Eto denote the same components, and descriptions thereof are omitted.

The display device520includes the color filter500, a counter substrate521such as a glass substrate, and a liquid crystal layer522formed of STN (super twisted nematic) liquid crystal compositions sandwiched therebetween. The color filter500is disposed on the upper side ofFIG. 7(on an observer side).

Although not shown, polarizing plates are disposed so as to face an outer surface of the counter substrate521and an outer surface of the color filter500(surfaces which are remote from the liquid crystal layer522). A backlight is disposed so as to face an outer surface of the polarizing plate disposed near the counter substrate521.

A plurality of rectangular first electrodes523extending in a horizontal direction inFIG. 13are formed with predetermined intervals therebetween on a surface of the protective film509(near the liquid crystal layer522) of the color filter500. A first alignment layer524is arranged so as to cover surfaces of the first electrodes523which are surfaces remote from the color filter500.

On the other hand, a plurality of rectangular second electrodes526extending in a direction perpendicular to the first electrodes523disposed on the color filter500are formed with predetermined intervals therebetween on a surface of the counter substrate521which faces the color filter500. A second alignment layer527is arranged so as to cover surfaces of the second electrodes526near the liquid crystal layer522. The first electrodes523and the second electrodes526are formed of a transparent conductive material such as an ITO.

A plurality of spacers528disposed in the liquid crystal layer522are used to maintain the thickness (cell gap) of the liquid crystal layer522constant. A seal member529is used to prevent the liquid crystal compositions in the liquid crystal layer522from leaking to the outside. Note that an end of each of the first electrodes523extends beyond the seal member529and serves as wiring523a.

Pixels are arranged at intersections of the first electrodes523and the second electrodes526. The coloring layers508R,508G, and508B are arranged on the color filter500so as to correspond to the pixels.

In normal manufacturing processing, the first electrodes523are patterned and the first alignment layer524is applied on the color filter500whereby a first half portion of the display device520on the color filter500side is manufactured. Similarly, the second electrodes526are patterned and the second alignment layer527is applied on the counter substrate521whereby a second half portion of the display device520on the counter substrate521side is manufactured. Thereafter, the spacers528and the seal member529are formed on the second half portion, and the first half portion is attached to the second half portion. Then, liquid crystal to be included in the liquid crystal layer522is injected from an inlet of the seal member529, and the inlet is sealed. Finally, the polarizing plates and the backlight are disposed.

The liquid droplet ejection apparatus1of this embodiment may apply a spacer material (functional liquid) constituting the cell gap, for example, and uniformly apply liquid crystal (functional liquid) to an area sealed by the seal member529before the first half portion is attached to the second half portion. Furthermore, the seal member529may be printed using the functional liquid droplet ejection heads17. Moreover, the first alignment layer524and the second alignment layer527may be applied using the functional liquid droplet ejection heads17.

FIG. 14is a sectional view of an essential part of a display device530and schematically illustrates a configuration thereof as a second example of a liquid crystal display device employing the color filter500which is manufactured in this embodiment.

The display device530is considerably different from the display device520in that the color filter500is disposed on a lower side inFIG. 14(remote from the observer).

The display device530is substantially configured such that a liquid crystal layer532constituted by STN liquid crystal is arranged between the color filter500and a counter substrate531such as a glass substrate. Although not shown, polarizing plates are disposed so as to face an outer surface of the counter substrate531and an outer surface of the color filter500.

A plurality of rectangular first electrodes533extending in a depth direction ofFIG. 14are formed with predetermined intervals therebetween on a surface of the protective film509(near the liquid crystal layer532) of the color filter500. A first alignment layer534is arranged so as to cover surfaces of the first electrodes533which are surfaces near the liquid crystal layer532.

On the other hand, a plurality of rectangular second electrodes536extending in a direction perpendicular to the first electrodes533disposed on the color filter500are formed with predetermined intervals therebetween on a surface of the counter substrate531which faces the color filter500. A second alignment layer537is arranged so as to cover surfaces of the second electrodes536near the liquid crystal layer532.

A plurality of spacers538disposed in the liquid crystal layer532are used to maintain the thickness (cell gap) of the liquid crystal layer532constant. A seal member539is used to prevent the liquid crystal compositions in the liquid crystal layer532from leaking to the outside.

As with the display device520, pixels are arranged at intersections of the first electrodes533and the second electrodes536. The coloring layers508R,508G, and508B are arranged on the color filter500so as to correspond to the pixels.

FIG. 15is an exploded perspective view of a transmissive TFT (thin film transistor) liquid crystal display device and schematically illustrates a configuration thereof as a third example of a liquid crystal display device employing the color filter500to which the invention is applied.

A liquid crystal display device550has the color filter500disposed on the upper side ofFIG. 15(on the observer side).

The liquid crystal display device550includes the color filter500, a counter substrate551disposed so as to face the color filter500, a liquid crystal layer (not shown) interposed therebetween, a polarizing plate555disposed so as to face an upper surface of the color filter500(on the observer side), and a polarizing plate (not shown) disposed so as to face a lower surface of the counter substrate551.

An electrode556used for driving the liquid crystal is formed on a surface of the protective film509(a surface near the counter substrate551) of the color filter500. The electrode556is formed of a transparent conductive material such as an ITO and entirely covers an area in which pixel electrodes560are to be formed which will be described later. An alignment layer557is arranged so as to cover a surface of the electrode556remote from the pixel electrode560.

An insulating film558is formed on a surface of the counter substrate551which faces the color filter500. On the insulating film558, scanning lines561and signal lines562are arranged so as to intersect with each other. Pixel electrodes560are formed in areas surrounded by the scanning lines561and the signal lines562. Note that an alignment layer (not shown) is arranged on the pixel electrodes560in an actual liquid crystal display device.

Thin-film transistors563each of which includes a source electrode, a drain electrode, a semiconductor layer, and a gate electrode are incorporated in areas surrounded by notch portions of the pixel electrodes560, the scanning lines561, and the signal lines562. When signals are supplied to the scanning lines561and the signal lines562, the thin-film transistors563are turned on or off so that power supply to the pixel electrodes560is controlled.

Note that although each of the display devices520,530, and550is configured as a transmissive liquid crystal display device, each of the display devices520,530, and550may be configured as a reflective liquid crystal display device having a reflective layer or a semi-transmissive liquid crystal display device having a semi-transmissive reflective layer.

FIG. 16is a sectional view illustrating an essential part of a display area of an organic EL device (hereinafter simply referred to as a display device600).

In this display device600, a circuit element portion602, a light-emitting element portion603, and a cathode604are laminated on a substrate (W)601.

In this display device600, light is emitted from the light-emitting element portion603through the circuit element portion602toward the substrate601and eventually is emitted to an observer side. In addition, light emitted from the light-emitting element portion603toward an opposite side of the substrate601is reflected by the cathode604, and thereafter passes through the circuit element portion602and the substrate601to be emitted to the observer side.

An underlayer protective film606formed of a silicon oxide film is arranged between the circuit element portion602and the substrate601. Semiconductor films607formed of polysilicon oxide films are formed on the underlayer protective film606(near the light-emitting element portion603) in an isolated manner. In each of the semiconductor films607, a source region607aand a drain region607bare formed on the left and right sides thereof, respectively, by high-concentration positive-ion implantation. The center portion of each of the semiconductor films607which is not subjected to high-concentration positive-ion implantation serves as a channel region607c.

In the circuit element portion602, the underlayer protective film606and a transparent gate insulating film608covering the semiconductor films607are formed. Gate electrodes609formed of, for example, Al, Mo, Ta, Ti, or W are disposed on the gate insulating film608so as to correspond to the channel regions607cof the semiconductor films607. A first transparent interlayer insulating film611aand a second transparent interlayer insulating film611bare formed on the gate electrodes609and the gate insulating film608. Contact holes612aand612bare formed so as to penetrate the first interlayer insulating film611aand the second interlayer insulating film611band to be connected to the source region607aand the drain region607bof the semiconductor films607.

Pixel electrodes613which are formed of ITOs, for example, and which are patterned to have a predetermined shape are formed on the second interlayer insulating film611b. The pixel electrode613is connected to the source region607athrough the contact holes612a.

Power source lines614are arranged on the first interlayer insulating film611a. The power source lines614are connected through the contact holes612bto the drain region607b.

Thus, the circuit element portion602includes thin-film transistors615connected to drive the respective pixel electrodes613.

The light-emitting element portion603includes functional layers617each formed on a corresponding one of pixel electrodes613, and bank portions618which are formed between the pixel electrodes613and the functional layers617and which are used to partition the functional layers617from one another.

The pixel electrodes613, the functional layers617, and the cathode604formed on the functional layers617constitute the light-emitting element. Note that the pixel electrodes613are formed into a substantially rectangular shape in plan view by patterning, and the bank portions618are formed so that each two of the pixel electrodes613sandwich a corresponding one of the bank portions618.

Each of the bank portions618includes an inorganic bank layer618a(first bank layer) formed of an inorganic material such as SiO, SiO2, or TiO2, and an organic bank layer618b(second bank layer) which is formed on the inorganic bank layer618aand has a trapezoidal shape in a sectional view. The organic bank layer618bis formed of a resist, such as an acrylic resin or a polyimide resin, which has an excellent heat resistance and an excellent lyophobic characteristic. A part of each of the bank portions618overlaps peripheries of corresponding two of the pixel electrodes613which sandwich each of the bank portions618.

Openings619are formed between the bank portions618so as to gradually increase in size upwardly against the pixel electrodes613.

Each of the functional layers617includes a positive-hole injection/transport layer617aformed so as to be laminated on the pixel electrodes613and a light-emitting layer617bformed on the positive-hole injection/transport layer617a. Note that another functional layer having another function may be arranged so as to be arranged adjacent to the light-emitting layer617b. For example, an electronic transport layer may be formed.

The positive-hole injection/transport layer617atransports positive holes from a corresponding one of the pixel electrodes613and injects the transported positive holes to the light-emitting layer617b. The positive-hole injection/transport layer617ais formed by ejection of a first composition (functional liquid) including a positive-hole injection/transport layer forming material. The positive-hole injection/transport layer forming material may be a known material.

The light-emitting layer617bis used for emission of light having colors red (R), green (G), or blue (B), and is formed by ejection of a second composition (functional liquid) including a material for forming the light-emitting layer617b(light-emitting material). As a solvent of the second composition (nonpolar solvent), a known material which is insoluble to the positive-hole injection/transport layer617ais preferably used. Since such a nonpolar solvent is used as the second composition of the light-emitting layer617b, the light-emitting layer617bcan be formed without dissolving the positive-hole injection/transport layer617aagain.

The light-emitting layer617bis configured such that the positive holes injected from the positive-hole injection/transport layer617aand electrons injected from the cathode604are recombined in the light-emitting layer617bso as to emit light.

The cathode604is formed so as to cover an entire surface of the light-emitting element portion603, and in combination with the pixel electrodes613, supplies current to the functional layers617. Note that a sealing member (not shown) is arranged on the cathode604.

Steps of manufacturing the display device600will now be described with reference toFIGS. 17 to 25.

As shown inFIG. 17, the display device600is manufactured through a bank portion forming step (S111), a surface processing step (S112), a positive-hole injection/transport layer forming step (S113), a light-emitting layer forming step (S114), and a counter electrode forming step (S115). Note that the manufacturing steps are not limited to these examples shown inFIG. 17, and one of these steps may be omitted or another step may be added according as desired.

In the bank portion forming step (S111), as shown inFIG. 18, the inorganic bank layers618aare formed on the second interlayer insulating film611b. The inorganic bank layers618aare formed by forming an inorganic film at a desired position and by patterning the inorganic film by the photolithography technique. At this time, a part of each of the inorganic bank layers618aoverlaps peripheries of corresponding two of the pixel electrodes613which sandwich each of the inorganic bank layers618a.

After the inorganic bank layers618aare formed, as shown inFIG. 19, the organic bank layers618bare formed on the inorganic bank layers618a. As with the inorganic bank layers618a, the organic bank layers618bare formed by patterning a formed organic film by the photolithography technique.

The bank portions618are thus formed. When the bank portions618are formed, the openings619opening upward relative to the pixel electrodes613are formed between the bank portions618. The openings619define pixel areas.

In the surface processing step (S112), a hydrophilic treatment and a repellency treatment are performed. The hydrophilic treatment is performed on first lamination areas618aaof the inorganic bank layers618aand electrode surfaces613aof the pixel electrodes613. The hydrophilic treatment is performed, for example, by plasma processing using oxide as a processing gas on surfaces of the first lamination areas618aaand the electrode surfaces613ato have hydrophilic properties. By performing the plasma processing, the ITO forming the pixel electrodes613is cleaned.

The repellency treatment is performed on walls618sof the organic bank layers618band upper surfaces618tof the organic bank layers618b. The repellency treatment is performed as a fluorination treatment, for example, by plasma processing using tetrafluoromethane as a processing gas on the walls618sand the upper surfaces618t.

By performing this surface processing step, when the functional layers617is formed using the functional liquid droplet ejection heads17, the functional liquid droplets are ejected onto the pixel areas with high accuracy. Furthermore, the functional liquid droplets attached onto the pixel areas are prevented from flowing out of the openings619.

A display device body600A is obtained through these steps. The display device body600A is mounted on the set table21of the liquid droplet ejection apparatus1shown inFIG. 1and the positive-hole injection/transport layer forming step (S113) and the light-emitting layer forming step (S114) are performed thereon.

As shown inFIG. 20, in the positive-hole injection/transport layer forming step (S113), the first compositions including the material for forming a positive-hole injection/transport layer are ejected from the functional liquid droplet ejection heads17into the openings619included in the pixel areas. Thereafter, as shown inFIG. 21, drying processing and a thermal treatment are performed to evaporate polar solution included in the first composition whereby the positive-hole injection/transport layers617aare formed on the pixel electrodes613(electrode surface613a).

The light-emitting layer forming step (S114) will now be described. In the light-emitting layer forming step, as described above, a nonpolar solvent which is insoluble to the positive-hole injection/transport layers617ais used as the solvent of the second composition used at the time of forming the light-emitting layer in order to prevent the positive-hole injection/transport layers617afrom being dissolved again.

On the other hand, since each of the positive-hole injection/transport layers617ahas low affinity to a nonpolar solvent, even when the second composition including the nonpolar solvent is ejected onto the positive-hole injection/transport layers617a, the positive-hole injection/transport layers617amay not be brought into tight contact with the light-emitting layers617bor the light-emitting layers617bmay not be uniformly applied.

Accordingly, before the light-emitting layers617bare formed, surface processing (surface improvement processing) is preferably performed so that each of the positive-hole injection/transport layers617ahas high affinity to the nonpolar solvent and to the material for forming the light-emitting layers. The surface processing is performed by applying a solvent the same as or similar to the nonpolar solvent of the second composition used at the time of forming the light-emitting layers on the positive-hole injection/transport layers617aand by drying the applied solvent.

Employment of this surface processing allows the surface of the positive-hole injection/transport layers617ato have high affinity to the nonpolar solvent, and therefore, the second composition including the material for forming the light-emitting layers can be uniformly applied to the positive-hole injection/transport layers617ain the subsequent step.

As shown inFIG. 22, a predetermined amount of second composition including the material for forming the light-emission layers of one of the three colors (blue color (B) in an example ofFIG. 22) is ejected into the pixel areas (openings619) as functional liquid. The second composition ejected into the pixel areas spreads over the positive-hole injection/transport layer617aand fills the openings619. Note that, even if the second composition is ejected and attached to the upper surfaces618tof the bank portions618which are outside of the pixel area, since the repellency treatment has been performed on the upper surfaces618tas described above, the second component easily drops into the openings619.

Thereafter, the drying processing is performed so that the ejected second composition is dried and the nonpolar solvent included in the second composition is evaporated whereby the light-emitting layers617bare formed on the positive-hole injection/transport layers617aas shown inFIG. 23. InFIG. 23, one of the light-emitting layers617bcorresponding to the blue color (B) is formed.

Similarly, as shown inFIG. 24, a step similar to the above-described step of forming the light-emitting layers617bcorresponding to the blue color (B) is repeatedly performed by using functional liquid droplet ejection heads17so that the light-emitting layers617bcorresponding to other colors (red (R) and green (G)) are formed. Note that the order of formation of the light-emitting layers617bis not limited to the order described above as an example, and any other orders may be applicable. For example, an order of forming the light-emitting layers617bmay be determined in accordance with a light-emitting layer forming material. Furthermore, the color scheme pattern of the three colors R, G, and B may be the stripe arrangement, the mosaic arrangement, or the delta arrangement.

As described above, the functional layers617, that is, the positive-hole injection/transport layers617aand the light-emitting layers617bare formed on the pixel electrodes613. Then, the process proceeds to the counter electrode forming step (S115).

In the counter electrode forming step (S115), as shown inFIG. 25, the cathode (counter electrode)604is formed on entire surfaces of the light-emitting layers617band the organic bank layers618bby an evaporation method, sputtering, or a CVD (chemical vapor deposition) method, for example. The cathode604is formed by laminating a calcium layer and an aluminum layer, for example, in this embodiment.

An Al film and a Ag film as electrodes and a protective layer formed of SiO2or SiN for preventing the Al film and the Ag film from being oxidized are formed on the cathode604.

After the cathode604is thus formed, other processes such as sealing processing of sealing a top surface of the cathode604with a sealing member and wiring processing are performed whereby the display device600is obtained.

FIG. 26is an exploded perspective view of an essential part of a plasma display device (PDP device: hereinafter simply referred to as a display device700). Note that, inFIG. 26, the display device700is partly cut away.

The display device700includes a first substrate701, a second substrate702which faces the first substrate701, and a discharge display portion703interposed therebetween. The discharge display portion703includes a plurality of discharge chambers705. The discharge chambers705include red discharge chambers705R, green discharge chambers705G, and blue discharge chambers705B, and are arranged so that one of the red discharge chambers705R, one of the green discharge chambers705G, and one of the blue discharge chambers705B constitute one pixel as a group.

Address electrodes706are arranged on the first substrate701with predetermined intervals therebetween in a stripe pattern, and a dielectric layer707is formed so as to cover top surfaces of the address electrodes706and the first substrate701. Partition walls708are arranged on the dielectric layer707so as to be arranged along with the address electrodes706in a standing manner between the adjacent address electrodes706. Some of the partition walls708extend in a width direction of the address electrodes706as shown inFIG. 26, and the others (not shown) extend perpendicular to the address electrodes706.

Regions partitioned by the partition walls708serve as the discharge chambers705.

The discharge chambers705include respective fluorescent substances709. Each of the fluorescent substances709emits light having one of the colors of red (R), green (G) and blue (B). The red discharge chamber705R has a red fluorescent substance709R on its bottom surface, the green discharge chamber705G has a green fluorescent substance709G on its bottom surface, and the blue discharge chamber705B has a blue fluorescent substance709B on its bottom surface.

On a lower surface of the second substrate702inFIG. 26, a plurality of display electrodes711are formed with predetermined intervals therebetween in a stripe manner in a direction perpendicular to the address electrodes706. A dielectric layer712and a protective film713formed of MgO, for example, are formed so as to cover the display electrodes711.

The first substrate701and the second substrate702are attached so that the address electrodes706are arranged perpendicular to the display electrodes711. Note that the address electrodes706and the display electrodes711are connected to an alternate power source (not shown).

When the address electrodes706and the display electrodes711are brought into conduction states, the fluorescent substances709are excited and emit light whereby display with colors is achieved.

In this embodiment, the address electrodes706, the display electrodes711, and the fluorescent substances709may be formed using the liquid droplet ejection apparatus1shown inFIG. 1. Steps of forming the address electrodes706on the first substrate701are described hereinafter.

The steps are performed in a state where the first substrate701is mounted on the set table21on the liquid droplet ejection apparatus1.

The functional liquid droplet ejection heads17eject a liquid material (functional liquid) including a material for forming a conducting film wiring as functional droplets to be attached onto regions for forming the address electrodes706. The material for forming a conducting film wiring included in the liquid material is formed by dispersing conductive fine particles such as those of a metal into dispersed media. Examples of the conductive fine particles include a metal fine particle including gold, silver, copper, palladium, or nickel, and a conductive polymer.

When ejection of the liquid material onto all the desired regions for forming the address electrodes706is completed, the ejected liquid material is dried, and the disperse media included in the liquid material is evaporated whereby the address electrodes706are formed.

Although the steps of forming the address electrodes706are described as an example above, the display electrodes711and the fluorescent substances709may be formed by the steps described above.

In a case where the display electrodes711are formed, as with the address electrodes706, a liquid material (functional liquid) including a material for forming a conducting film wiring is ejected from the functional liquid droplet ejection heads17as liquid droplets to be attached to the areas for forming the display electrodes.

In a case where the fluorescent substances709are formed, a liquid material including fluorescent materials corresponding to three colors (R, G, and B) is ejected as liquid droplets from the functional liquid droplet ejection heads17so that liquid droplets having the three colors (R, G, and B) are attached within the discharge chambers705.

FIG. 27shows a sectional view of an essential part of an electron emission device (also referred to as a FED device or a SED device: hereinafter simply referred to as a display device800). InFIG. 27, a part of the display device800is shown in the sectional view.

The display device800includes a first substrate801, a second substrate802which faces the first substrate801, and a field-emission display portion803interposed therebetween. The field-emission display portion803includes a plurality of electron emission portions805arranged in a matrix.

First element electrodes806aand second element electrodes806b, and conductive films807are arranged on the first substrate801. The first element electrodes806aand the second element electrodes806bintersect with each other. Cathode electrodes806are formed on the first substrate801, and each of the cathode electrodes806is constituted by one of the first element electrodes806aand one of the second element electrodes806b. In each of the cathode electrodes806, one of the conductive films807having a gap808is formed in a portion formed by the first element electrode806aand the second element electrode806b. That is, the first element electrodes806a, the second element electrodes806b, and the conductive films807constitute the plurality of electron emission portions805. Each of the conductive films807is constituted by palladium oxide (PdO). In each of the cathode electrodes806, the gap808is formed by forming processing after the corresponding one of the conductive films807is formed.

An anode electrode809is formed on a lower surface of the second substrate802so as to face the cathode electrodes806. A bank portion811is formed on a lower surface of the anode electrode809in a lattice. Fluorescent materials813are arranged in opening portions812which opens downward and which are surrounded by the bank portion811. The fluorescent materials813correspond to the electron emission portions805. Each of the fluorescent materials813emits fluorescent light having one of the three colors, red (R), green (G), and blue (B). Red fluorescent materials813R, green fluorescent materials813G, and blue fluorescent materials813B are arranged in the opening portions812in a predetermined arrangement pattern described above.

The first substrate801and the second substrate802thus configured are attached with each other with a small gap therebetween. In this display device800, electrons emitted from the first element electrodes806aor the second element electrodes806bincluded in the cathode electrodes806hit the fluorescent materials813formed on the anode electrode809so that the fluorescent materials813are excited and emit light whereby display with colors is achieved.

As with the other embodiments, in this case also, the first element electrodes806a, the second element electrodes806b, the conductive films807, and the anode electrode809may be formed using the liquid droplet ejection apparatus1. In addition, the red fluorescent materials813R, the green fluorescent materials813G, and the blue fluorescent materials813B may be formed using the liquid droplet ejection apparatus1.

Each of the first element electrodes806a, each of the second element electrodes806b, and each of the conductive films807have shapes as shown inFIG. 28A. When the first element electrodes806a, the second element electrodes806b, and the conductive films807are formed, portions for forming the first element electrodes806a, the second element electrodes806b, and the conductive films807are left as they are on the first substrate801and only bank portions BB are formed (by a photolithography method) as shown inFIG. 28B. Then, the first element electrodes806aand the second element electrodes806bare formed by an inkjet method using a solvent ejected from the liquid droplet ejection apparatus1in grooves defined by the bank portions BB and are formed by drying the solvent. Thereafter, the conductive films807are formed by the inkjet method using the liquid droplet ejection apparatus1. After forming the conductive films807, the bank portions BB are removed by ashing processing and the forming processing is performed. Note that, as with the case of the organic EL device, the hydrophilic treatment is preferably performed on the first substrate801and the second substrate802and the repellency treatment is preferably performed on the bank portion811and the bank portions BB.

Examples of other electro-optical devices include a device for forming metal wiring, a device for forming a lens, a device for forming a resist, and a device for forming an optical diffusion body. Use of the liquid droplet ejection apparatus1makes it possible to efficiently manufacture various electro-optical devices.