U.S. patent application number 12/556687 was filed with the patent office on 2009-12-31 for method for forming mark and liquid ejection apparatus.
This patent application is currently assigned to SEIKO EPSON CORPORATION. Invention is credited to Yuji Iwata.
Application Number | 20090324766 12/556687 |
Document ID | / |
Family ID | 37995726 |
Filed Date | 2009-12-31 |
United States Patent
Application |
20090324766 |
Kind Code |
A1 |
Iwata; Yuji |
December 31, 2009 |
METHOD FOR FORMING MARK AND LIQUID EJECTION APPARATUS
Abstract
A method for forming a mark includes ejecting a droplet of a
liquid from a nozzle onto an ejection target position on a surface
of an object along an ejecting direction; radiating a laser beam
from a radiation port onto the ejection target position along a
radiating direction; and pivoting the nozzle and the radiation port
together about the ejection target position as a pivot center,
thereby changing the angle between a normal line of the surface of
the object and the ejecting direction and the angle between the
normal line and the radiating direction while maintaining the angle
between the ejecting direction and the radiating direction.
Inventors: |
Iwata; Yuji; (Suwa,
JP) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
SEIKO EPSON CORPORATION
Tokyo
JP
|
Family ID: |
37995726 |
Appl. No.: |
12/556687 |
Filed: |
September 10, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11591413 |
Oct 26, 2006 |
7604848 |
|
|
12556687 |
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Current U.S.
Class: |
425/174.4 |
Current CPC
Class: |
B41J 25/001 20130101;
B41J 11/002 20130101 |
Class at
Publication: |
425/174.4 |
International
Class: |
B29B 15/10 20060101
B29B015/10 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 28, 2005 |
JP |
2005-315138 |
Oct 10, 2006 |
JP |
2006-276856 |
Claims
1. A liquid ejection apparatus comprising: a liquid ejection head
having a nozzle, the liquid ejection head ejecting a droplet of a
liquid from the nozzle onto an ejection target position on a
surface of an object along an ejecting direction; a laser radiation
device having a radiation port, the laser radiation device
radiating a laser beam from the radiation port onto the ejection
target position along a radiating direction; and a pivot device
that pivots the nozzle and the radiation port together about the
ejection target position as a pivot center, thereby changing the
angle between a normal line of the surface of the object and the
ejecting direction and the angle between the normal line and the
radiating direction while maintaining the angle between the
ejecting direction and the radiating direction.
2. The apparatus according to claim 1, wherein the pivot device
pivots the nozzle and the radiation port together in such a manner
that the radiating direction becomes substantially parallel with
the normal line.
3. The apparatus according to claim 1, wherein the pivot device has
a pivot stage that pivots about the ejection target position as a
pivot center, the liquid ejection head and the laser radiation
device being mounted on the pivot stage, the liquid ejection
apparatus further including a carriage movable relative to the
surface of the object, the pivot stage being mounted on the
carriage.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This is a divisional application of U.S. Ser. No. 11/591,413
filed Oct. 26, 2006, claiming priority to Japanese Patent
Application No. 2005-315138, filed on Oct. 28, 2005, and Japanese
Patent Application No. 2006-276856, filed on Oct. 10, 2006, all of
which are expressly incorporated by reference herein.
BACKGROUND
[0002] 1. Technical Field
[0003] The present invention relates to a method for forming a mark
and a liquid ejection apparatus.
[0004] 2. Related Art
[0005] Normally, an electro-optic apparatus such as a liquid
crystal display or an electroluminescence display includes a
substrate that displays an image. The substrate has an
identification code (for example, a two-dimensional code) including
product information regarding the name of the manufacturer and the
product number, for purposes of quality control and production
control. The identification code includes a plurality of dots
formed by, for example, colored thin films or recesses. The dots
are arranged in a predetermined pattern so that the identification
code can be identified in accordance with the arrangement pattern
of the dots.
[0006] As a method for forming an identification code,
JP-A-11-77340 discloses a laser sputtering method and
JP-A-2003-127537 discloses a waterjet method. In the laser
sputtering method, a code pattern is formed through sputtering by
radiating a laser beam onto a metal foil. In the waterjet method,
dots are marked on a substrate by ejecting water containing
abrasive onto the substrate.
[0007] However, in the laser sputtering method, the interval
between the metal foil and the substrate must be adjusted to
several micrometers to several tens of micrometers in order to form
each dot in a desired size. The substrate and the metal foil thus
must have extremely flat surfaces and adjustment of the interval
between the substrate and the metal foil must be carried out with
accuracy on the order of micrometers. This limits application of
the method to a restricted range of substrate, and the use of the
method is limited. In the waterjet method, the substrate may be
contaminated by water, dust, and the abrasive that are splashed
when the identification code is formed.
[0008] In order to solve these problems, an inkjet method has been
focused on as an alternative method for forming an identification
code. In the inkjet method, dots are provided on a substrate by
ejecting droplets of liquid containing metal particles from nozzles
of an ejection head onto the substrate. The droplets are then dried
to provide the dots. The method thus can be applied to a relatively
wide range of substrate materials. Further, the method prevents
contamination of the substrate caused by formation of the
identification code.
[0009] However, the inkjet method may cause the following problem
in correspondence with the surface condition of a substrate or
surface tension of a droplet. Specifically, immediately after
having been received by a substrate, a droplet starts to spread wet
on the surface of the substrate. Thus, if the time necessary for
the droplet to be dried is excessively long (for example, 100
milliseconds or longer), the droplet may spread excessively on the
surface of the substrate and overflow from the corresponding data
cell. This makes the code pattern unreadable, which causes loss of
the information regarding the substrate.
[0010] This problem may be avoided by radiating a laser beam onto
the droplet on the substrate and instantly drying the droplet.
However, in a typical liquid ejection head, the interval between
the nozzles and the surface of the substrate is maintained at
several millimeters to improve position accuracy of reception of an
ejected droplet by the substrate. The laser beam thus must be
radiated onto the droplet toward the narrow distance between the
ejection head and the substrate immediately after the droplet has
been received by the substrate. That is, it is necessary to greatly
incline the optical axis of the laser beam with respect to a normal
direction of the surface of the substrate. Accordingly, the optical
cross section of the laser beam, or a beam spot, with respect to
the surface of the substrate or the droplet becomes excessively
large on the surface of the substrate. This may lower the radiation
intensity of the laser beam or the position accuracy of radiation
of the laser beam.
SUMMARY OF THE INVENTION
[0011] Accordingly, it is an objective of the present invention to
provide a method for forming a mark and a liquid ejection apparatus
that improve controllability for shaping the mark formed by
droplets of liquid by maintaining the position accuracy of
reception of ejected droplets by a substrate and that of the
radiation of laser beams.
[0012] According one aspect of the invention, a method for forming
a mark includes ejecting a droplet of a liquid from a nozzle onto
an ejection target position on a surface of an object along an
ejecting direction; radiating a laser beam from a radiation port
onto the ejection target position along a radiating direction; and
pivoting the nozzle and the radiation port together about the
ejection target position as a pivot center, thereby changing the
angle between a normal line of the surface of the object and the
ejecting direction and the angle between the normal line and the
radiating direction while maintaining the angle between the
ejecting direction and the radiating direction.
[0013] According to another aspect of the invention, a liquid
ejection apparatus includes a liquid ejection head, a laser
radiation device, and a pivot device. The liquid ejection head has
a nozzle. The liquid ejection head ejects a droplet of a liquid
from the nozzle onto an ejection target position on a surface of an
object along an ejecting direction. The laser radiation device has
a radiation port. The laser radiation device radiates a laser beam
from the radiation port onto the ejection target position along a
radiating direction. The pivot device pivots the nozzle and the
radiation port together about the ejection target position as a
pivot center, thereby changing the angle between a normal line of
the surface of the object and the ejecting direction and the angle
between the normal line and the radiating direction while
maintaining the angle between the ejecting direction and the
radiating direction.
[0014] Other aspects and advantages of the invention will become
apparent from the following description, taken in conjunction with
the accompanying drawings, illustrating by way of example the
principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The invention, together with objects and advantages thereof,
may best be understood by reference to the following description of
the presently preferred embodiments together with the accompanying
drawings in which:
[0016] FIG. 1 is a plan view illustrating a liquid crystal
display;
[0017] FIG. 2 is a perspective view schematically illustrating a
liquid ejection apparatus;
[0018] FIG. 3 is a perspective view schematically illustrating an
ejection head according to a first embodiment of the present
invention;
[0019] FIG. 4 is a view illustrating the ejection head of FIG.
3;
[0020] FIG. 4A is an enlarged partial view of a part of FIG. 4
indicated by a circle 4A;
[0021] FIG. 5 is a view illustrating the ejection head of FIG.
3;
[0022] FIG. 5A is an enlarged partial view of a part of FIG. 5
indicated by a circle 5A; and
[0023] FIG. 6 is a block diagram representing the electric
configuration of the liquid ejection apparatus.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] A first embodiment of the present invention will now be
described with reference to FIGS. 1 to 6. First, a liquid crystal
display 1 having an identification code formed by a method for
forming a mark according to the present invention will be
explained.
[0025] As illustrated in FIG. 1, a display portion 3 is formed on
one of the surfaces of a substrate 2 of the liquid crystal display
1, or on a surface 2a. The substrate 2 is an object onto which
droplets of liquid are ejected. The display portion 3 has a
rectangular shape. Liquid crystal molecules are sealed in a
substantial central portion of the display portion 3. The surface
2a receives droplets of liquid that have been ejected. A scanning
line driver circuit 4 and a data line driver circuit 5 are formed
outside the display portion 3. The liquid crystal display 1
controls orientation of the liquid crystal molecules in the display
portion 3 in correspondence with scanning signals generated by the
scanning line driver circuit 4 and data signals generated by the
data line driver circuit 5. The liquid crystal display 1 modulates
area light emitted from a lighting device (not illustrated) in
accordance with an orientation state of the liquid crystal
molecules, thus displaying a desired image in an area of the
display portion 3.
[0026] Referring to FIG. 1, a code formation area S (indicated by
the circle in the double-dotted chain line), a square each side of
which is approximately 1 mm long, is defined in the lower left
corner of the surface 2a. The code formation area S is virtually
divided into data cells C of 16 rows by 16 lines. A dot (or a mark)
D is formed in each of some selected data cells C. The dots D are
arranged in accordance with a prescribed pattern, forming an
identification code 10 of the liquid crystal display 1.
[0027] In the first embodiment, an ejection target position P
corresponds to the center of each of the data cells C in which the
dots D are provided. The cell width W is the length of each side of
the data cell D.
[0028] Each dot D has a semispherical shape with an outer diameter
coinciding with the length of each side of the data cell C, or the
cell width W. To form the dots D, droplets Fb of liquid F (see FIG.
4) prepared by dispersing metal particles (for example, nickel or
manganese particles), or dot forming material, in dispersion medium
are ejected onto the selected data cells C. The droplets Fb are
then dried and baked in the corresponding data cells C. Such drying
and baking of the droplets Fb is performed through radiation of
laser beams B (see FIG. 5). In the first embodiment, the dots D are
formed by drying and baking the droplets Fb. However, formation of
the dots D may be carried out in any other suitable manner. For
example, the dots D may be provided simply by drying the laser
beams B.
[0029] The identification code 10 may reproduce product information
of the liquid crystal display 1 including the product number or the
lot number in accordance with the pattern formed by the dots D in
the data cells C.
[0030] In FIGS. 1 to 5, direction X corresponds to a longitudinal
direction of the substrate 2. Direction Y corresponds to a lateral
direction of the substrate 2, or a direction perpendicular to
direction X. Direction Z is a direction vertical to directions X
and Y. Specifically, the directions indicated by the arrows of the
drawings will be referred to as defined as direction +X, direction
+Y, and direction +Z. The directions opposite to these directions
will be referred to as direction -X, direction -Y, and direction
-Z.
[0031] Next, a liquid ejection apparatus 20 by which the
identification code 10 is formed will be explained. As illustrated
in FIG. 2, the liquid ejection apparatus 20 has a base 21. The base
21 is formed in a parallelepiped shape and the longitudinal
direction of the base 21 corresponds to direction X. A pair of
guide grooves 22, which extend in direction X, are defined in an
upper surface of the base 21. A substrate stage 23, which serves as
a transporting device, is provided on the base 21. The substrate
stage 23 is operably connected to an X-axis motor MX (see FIG. 6)
that is provided on the base 21 and translated and slides along the
guide grooves 22 in direction X at a predetermined speed (transport
speed Vx). A suction type chuck mechanism (not illustrated) is
arranged on the substrate stage 23. The substrate 2 is positioned
and fixed to an upper surface of the substrate stage 23 with the
surface 2a (the code formation area S) facing upward.
[0032] A guide member 24 extends in direction Y of the base 21. As
viewed in direction X, the guide member 24 is shaped like a gate. A
reservoir tank 25 is provided on the guide member 24. The reservoir
tank 25 retains the liquid F and supplies the liquid F to an
ejection head 32. A pair of guide rails 26 are formed below the
guide member 24, extending along the entire width of the guide
member 24 in direction Y. A carriage 27 is operably connected to a
Y-axis motor MY (see FIG. 6) that is provided on the guide member
24 and linearly moves on the guide rails 26.
[0033] As illustrated in FIG. 4, a guide member 28 is located on a
lower surface of the carriage 27. The guide member 28 has a
parallelepiped shape and extends in direction Y. The guide member
28 has a guide surface 28a, which is formed substantially along the
entire width of the carriage 27 in direction Y. The guide surface
28a is a concave surface shaped in an arcuate manner having a
center of radius Cr located on the surface 2a of the substrate
2.
[0034] A pivot stage 29, which extends in direction Y, is provided
on the guide surface 28a of the guide member 28. The pivot stage 29
forms a pivot device. The pivot stage 29 has a convex surface
opposed to the guide surface 28a, or a sliding surface 29a, at the
side corresponding to the guide member 28. The pivot stage 29 also
has a flat surface extending along the surface 2a of the substrate
2, or a stage surface 29b, at the side corresponding to the
substrate stage 23. The pivot stage 29 is operably connected to a
pivot motor MR (see FIG. 6) through a worm gear (not illustrated)
formed in the guide member 28. The pivot stage 29 operates in such
a manner that the sliding surface 29a slides on or pivots along the
guide surface 28a. In other words, the stage surface 29b of the
pivot stage 29 pivots about the center of radius Cr in such a
manner that the sliding surface 29a and the guide surface 28a
become flush.
[0035] In the illustrated embodiment, as illustrated in FIG. 4, the
reference position of the pivot stage 29 corresponds to the
position of the pivot stage 29 at which the sliding surface 29a
coincides with the guide surface 28a. Further, as illustrated in
FIG. 5, the imaging position of the pivot stage 29 corresponds to
the position of the pivot stage 29 with the sliding surface 29a
pivoted clockwise at a predetermined angle (the pivot angle
.theta.r).
[0036] As illustrated in FIG. 3, a plate-like support member 31
connected to legs is provided on the stage surface 29b of the pivot
stage 29. The legs extend toward the substrate 2, or in direction
-Z. The ejection head 32 is supported by the support member 31 at
the side corresponding to the substrate 2, or at a position in
direction -Z from the support member 31.
[0037] A nozzle plate 33 is formed on an upper surface of the
ejection head 32 as viewed in FIG. 3. The nozzle plate 33 has a
nozzle-forming surface 33a parallel with the stage surface 29b at
the side corresponding to the substrate 2. Sixteen circular bores,
or nozzles N, are defined in the nozzle-forming surface 33a and
spaced at equal intervals (the pitch width corresponding to the
cell width W) in direction Y.
[0038] With reference to FIG. 4, each of the nozzles N extends in a
normal direction of the nozzle-forming surface 33a and in a radial
direction of the sliding surface 29a. In FIG. 4, the ejecting
direction A1 corresponds to the radial direction of the sliding
surface 29a, or an orienting direction of each nozzle N. The
droplet receiving position PF corresponds to the center of radius
Cr and is a position on the surface 2a at which a droplet Fb is
received by the substrate 2.
[0039] As illustrated in FIG. 4A, a cavity 34 is defined above each
of the nozzles N and communicates with the reservoir tank 25. Each
of the cavities 34 supplies the liquid F from the reservoir tank 25
to the corresponding one of the nozzles N. An oscillation plate 35
is attached with the upper surfaces of the walls defining each of
the cavities 34. Each of the oscillation plates 35 oscillates in an
upward-downward direction and increases or reduces the volume of
the corresponding one of the cavities 34. Sixteen piezoelectric
elements PZ, which correspond to nozzles N respectively, are
arranged on the oscillation plates 35. Each of the piezoelectric
elements PZ is excited in response to a signal for controlling
actuation of the piezoelectric element PZ (piezoelectric element
drive voltage COM1: see FIG. 6), and causes oscillation of the
corresponding one of the oscillation plates 35 in the
upward-downward direction. The droplets Fb are then ejected from
the corresponding nozzles N in the ejection direction A1.
[0040] A signal (a pivot motor signal SMR: see FIG. 6) for pivoting
the pivot stage 29 from the reference position to the imaging
position is sent to the pivot motor MR, which causes forward
rotation of the pivot motor MR. This pivots the stage surface 29b
of the pivot stage 29 (the nozzle-forming surface 33a) clockwise
about the droplet receiving position PF, the pivot center, at the
pivot angle .theta.r. In this manner, as illustrated in FIG. 5, the
distance between the ejection head 32 (the nozzle-forming surface
33a) and the substrate 2 in which the laser head 37 is provided is
enlarged at the side of +Z direction of the ejection head 32 or at
the side corresponding to the laser head 37. The laser head 37
serves as a laser-irradiating device.
[0041] Subsequently, in correspondence with the timing at which the
ejection target positions P of the data cells C reach the
corresponding droplet receiving positions PF, the piezoelectric
element drive voltage COM 1 is supplied to the corresponding
piezoelectric elements PZ. As shown in FIG. 5A, the piezoelectric
elements PZ then causes the droplets Fb to travel from the nozzles
N in the ejecting direction A1 (in a radial inward direction of the
sliding surface 29a). Since the droplets Fb travel along direction
A1, the droplets reach the corresponding droplet receiving
positions PF regardless of the measure of the pivot angle .theta.r.
The droplets Fb then spread wet on the surface 2a. The outer
diameter of each droplet Fb coincides with the cell width W.
[0042] Accordingly, the ejection head 32 enlarges the distance
between the nozzle-forming surface 33a and the substrate 2 at the
side corresponding to the laser head 37, while maintaining the
position accuracy of reception of the droplets Fb by the substrate
2.
[0043] Referring to FIG. 3, a substantially triangular prism-like
support member 36, which extends in direction Y, is located on the
stage surface 29b of the pivot stage 29 at a position in direction
+X from the ejection head 32. The laser head 37, which extends in
direction Y and has a parallelepiped shape, is supported by the
side of the support member 36 corresponding to the substrate 2, or
at a position in direction -Z from the support member 36.
[0044] Semiconductor lasers LD (see FIG. 6) are provided in the
laser head 37 in correspondence with the nozzles N. Upon receiving
a signal (laser drive voltage COM2: see FIG. 6) for driving the
semiconductor lasers LD, each of the semiconductor lasers LD
radiates laser beams having a wavelength range corresponding to
absorption wavelength of each droplet Fb. The laser head 37, on the
side corresponding to the substrate, defines sixteen radiation
ports 38 that are spaced at equal intervals (the pitch width
corresponding to the cell width W) in direction Y. The radiation
ports 38 correspond to the respective nozzles N.
[0045] With reference to FIG. 4, each of radiation ports 38 defines
an optical axis extending toward the corresponding droplet
receiving position PF in a radial direction of the sliding surface
29a. A laser beam B (see FIG. 5) is radiated from each port 38
along the optical axis.
[0046] As illustrated in FIG. 4A, the radiating direction A2
corresponds to the optical axis, which passes through the
corresponding radiation port 38. The radiation angle .theta.b is
the angle between the radiating direction A2 and the normal
direction of the surface 2a.
[0047] As the pivot stage 29 pivots from the reference position to
the imaging position, each of the radiation ports 38 pivots
clockwise about the corresponding droplet receiving position PF,
the pivot center. As a result, the radiating direction A2
approximates to the normal direction of the substrate 2 and the
radiation angle .theta.b decreases by the amount corresponding to
the pivot angle .theta.r.
[0048] Subsequently, in correspondence with the timing at which the
ejection target positions P of the data cells C reach the
corresponding droplet receiving positions PF, the laser drive
voltage COM2 is supplied to the corresponding semiconductor lasers
LD. The lasers LD then radiates laser beam B from each of the
associated radiation ports 38 in the radiating direction A2.
[0049] By this time, the distance between the nozzle-forming
surface 33a and the substrate 2 has been enlarged in the vicinity
of the laser head 37 through pivoting of the ejection head 32.
Therefore, the laser beam B proceeding in the radiating direction
A2 is radiated onto the corresponding droplet receiving position PF
(the corresponding ejection target position P), or the pivot
center, without being blocked by the ejection head 32. In other
words, the radiation angle .theta.b of the laser beam B is
decreased while the its irradiated location is kept on the location
PF, whereby the zone corresponding to the droplet Fb (the outer
diameter of which coincides with the cell width W) is irradiated.
Thus, the laser head 37 may vary the radiation angle .theta.b or
energy density of the laser beam B while maintaining the radiating
position and the position accuracy.
[0050] In this manner, the laser head 37 may always irradiate the
zone corresponding to the droplets Fb with the laser beam B having
a decreased angle .theta.b (the increased energy density) by the
amount corresponding to the pivot angle .theta.r. The laser head 37
provides sufficient drying of the droplets Fb, allowing dots D
having the outer diameter coinciding with the cell width W formed
in the corresponding data cells C.
[0051] The electric configuration of the liquid ejection apparatus
20 will hereafter be described with reference to FIG. 6.
[0052] Referring to FIG. 6, a controller 41 includes a CPU, a RAM,
and a ROM. The ROM stores various data and various control
programs. The controller 41 transports the substrate stage 23 and
operates the ejection head 32, the laser head 37, and the pivot
stage 29 in correspondence with the data and in accordance with the
control programs.
[0053] An input device 42 including manipulation switches such as a
start switch or a stop switch is connected to the controller 41. An
image of the identification code 10 is input from the input device
42 to the controller 41 as a prescribed form of imaging data Ia.
The pivot angle .theta.r of the pivot stage 29 is also input from
the input device 42 to the controller 41 as a prescribed form of
pivot angle data I.theta.. In correspondence with the imaging data
Ia input from the input device 42, the controller 41 generates bit
map data BMD, the piezoelectric element drive voltage COM1, and the
laser drive voltage COM2. Further, the input device 42 generates a
pivot motor drive signal SMR in correspondence with the pivot angle
data I.theta. input from the input device 42.
[0054] The bit map data BMD indicates whether to excite the
piezoelectric elements PZ in correspondence with the corresponding
bit values (0 or 1). That is, the bit map data BMD indicates
whether to eject the droplets Fb onto the data cells C defined in a
two-dimensional imaging surface (the code formation area S).
[0055] The controller 41 is connected to an X-axis motor driver
circuit 43 and outputs a corresponding control signal to the X-axis
motor driver circuit 43. In correspondence with the control signal
of the controller 41, the X-axis motor driver circuit 43 operates
to rotate the X-axis motor MX in a forward direction or a reverse
direction. The controller 41 is connected to a Y-axis motor driver
circuit 44 and outputs a corresponding control signal to the Y-axis
motor driver circuit 44. In correspondence with the control signal
of the controller 41, the Y-axis motor driver circuit 44 operates
to rotate the Y-axis motor MY in a forward direction or a reverse
direction. The controller 41 is connected to a substrate detector
45 capable of detecting an end of the substrate 2. The controller
41 calculates the position of the substrate 2 that is passing the
droplet receiving position PF, based on a detection signal
generated by the substrate detector 45.
[0056] An X-axis motor rotation detector 46 is connected to the
controller 41 and sends a detection signal to the controller 41. In
correspondence with the detection signal of the X-axis motor
rotation detector 46, the controller 41 calculates the movement
direction and the movement amount (the current position) of the
substrate stage 23 (the substrate 2) The controller 41 sends an
ejection timing signal LP1 to an ejection head driver circuit 48
when the center of each data cell C coincides with the
corresponding droplet receiving position PF.
[0057] A Y-axis motor rotation detector 47 is connected to the
controller 41 and outputs a detection signal to the controller 41.
In correspondence with the detection signal of the Y-axis motor
rotation detector 47, the controller 41 calculates the movement
direction and the movement amount (the current position) of the
ejection head 32 (the laser head 37) in direction Y. The controller
41 then operates in such a manner that the droplet receiving
positions PF corresponding to the nozzles N are located on the
movement paths of the corresponding ejection target positions
P.
[0058] The controller 41 is connected to an ejection head driver
circuit 48 and provides an ejection timing signal LP1 to the
ejection head driver circuit 48. The controller 41 synchronizes the
piezoelectric element drive voltage COM1 with a prescribed clock
signal and supplies the piezoelectric element drive voltage COM1 to
the ejection head driver circuit 48. Further, the controller 41
generates ejection control signals SI synchronized with a
prescribed reference clock signal based on the bit map data BMD and
serially transfers the ejection control signals SI to the ejection
head driver circuit 48. The ejection head driver circuit 48
converts the serial ejection control signals SI from the controller
41 to the parallel signals corresponding to the piezoelectric
elements PZ.
[0059] Upon receiving the ejection timing signal LP1 from the
controller 41, the ejection head driver circuit 48 supplies the
piezoelectric element drive voltage COM1 to the piezoelectric
elements PZ that are selected in correspondence with the ejection
control signals SI. Further, the ejection head driver circuit 48
outputs the parallel ejection control signals SI, which have been
converted from the serial signals, to a laser driver circuit
49.
[0060] The controller 41 is connected to the laser driver circuit
49 and outputs the laser drive voltage COM2 to the laser driver
circuit 49 synchronously with a prescribed clock signal.
[0061] Upon receiving the ejection control signals SI from the
ejection head driver circuit 48, the laser driver circuit 49 waits
a predetermined time (radiation standby time) and then supplies the
laser drive voltage COM2 to the respective semiconductor lasers LD
corresponding to the ejection control signals SI. In other words,
every time the droplets Fb on the substrate 2 reach the radiation
target positions PT, the controller 41 operates the laser driver
circuit 49 to radiate the laser beams B onto the zones where the
droplets Fb are disposed.
[0062] The controller 41 is connected to a pivot motor driver
circuit 50 and sends a pivot motor drive signal SMR to the pivot
motor driver circuit 50. In response to the pivot motor drive
signal SMR from the controller 41, the pivot motor driver circuit
50 operates to rotate the pivot motor MR, which drives the pivot
stage 29 to pivot, in a forward or reverse direction. In this
manner, the pivot stage 29 (the radiation ports 37a are) pivoted at
the pivot angle .theta.r.
[0063] A method for forming the identification code 10 using the
liquid ejection apparatus 20 will hereafter be described.
[0064] First, as illustrated in FIG. 2, the substrate 2 is fixed to
the substrate stage 23 with the surface 2a facing upward. At this
stage, the substrate 2 is located on the side of direction -X with
respect to the guide member 24 (the carriage 27). The pivot stage
29 is arranged at the reference position.
[0065] The input device 42 is then manipulated to input the imaging
data Ia and the pivot angle data I.theta. to the controller 41. The
controller 41 then generates and stores the bit map data BMD in
correspondence with the imaging data Ia and produces the
piezoelectric element drive voltage COM1 and the laser drive
voltage COM2. Subsequently, the controller 41 starts operating the
Y-axis motor MY. The carriage 27 is (the nozzles N are) thus set at
a position (positions) in direction Y in such a manner that, when
the substrate 2 is transported in direction +X, the ejection target
positions P pass the corresponding droplet receiving positions
PF.
[0066] Further, the controller 41 generates the pivot motor drive
signal SMR based on the pivot angle data I.theta. and outputs the
pivot motor drive signal SMR to the pivot motor driver circuit 50.
The controller 41 then operates the pivot motor driver circuit 50
to rotate the pivot motor MR in the forward direction, thus
pivoting the pivot stage 29 from the reference position to the
radiating position. In this manner, while maintaining the position
at which the droplet Fb from each nozzle N is received by the
substrate 2 and the radiating position of the laser beam B from
each radiation port 38 commonly at the corresponding droplet
receiving position PT, the radiation angle .theta.b of each laser
beam B is decreased by the amount corresponding to the pivot angle
.theta.r independently.
[0067] After having pivoted the pivot stage 29 to the radiating
position, the controller 41 operates the X-axis motor MX to start
transportation of the substrate 2 in direction +X. The controller
41 determines whether the ejection target positions P of the
foremost ones of the data cells C in direction X have reached the
positions immediately below the nozzles N, in correspondence with
the detection signals of the substrate detector 45 and the X-axis
motor rotation detector 46.
[0068] Meanwhile, the controller 41 outputs the ejection control
signals SI to the ejection head driver circuit 48 and supplies the
piezoelectric drive voltage COM1 and the laser drive voltage COM2
to the ejection head driver circuit 48 and the laser driver circuit
49, respectively.
[0069] When the ejection target positions P of the foremost ones of
the data cells C in direction +X reach the corresponding droplet
receiving positions PF, the controller 41 outputs the ejection
timing signal LP1 to the ejection head driver circuit 48.
[0070] After having sent the ejection timing signal LP1 to the
ejection head driver circuit 48, the controller 41 operates the
ejection head driver circuit 48 to supply the piezoelectric element
drive voltage COM1 to the piezoelectric elements PZ selected based
on the ejection control signals SI. In this manner, the
corresponding nozzles N are caused to simultaneously eject the
droplets Fb. The droplets Fb are then received by the substrate 2
at the corresponding ejection target positions P. The droplets Fb
spread wet in the corresponding data cells C as time elapses. By
the time the radiation standby time elapses since starting of
ejection, the outer diameter of the droplets Fb in the droplet
receiving position PF becomes the cell width W.
[0071] Further, after having output the ejection timing signal LP1
to the ejection head driver circuit 48, the controller 41 supplies
the laser drive voltage COM2 to the semiconductor lasers LD
selected in correspondence with the ejection control signals SI
from the ejection head driver circuit 48. The controller 41 thus
operates to simultaneously radiate the laser beams B from the
selected semiconductor lasers LD.
[0072] The radiation angle .theta. of the laser beams B from the
semiconductor lasers LD is decreased by the amount corresponding to
the pivot angle .theta.r, which increases the energy density of the
laser beams B with respect to the corresponding droplets Fb. In
this manner, while avoiding insufficiency of radiation energy of
the laser beams B with respect to the droplets Fb, or insufficient
drying of the droplets Fb, the laser beams B form dots D having the
outer diameter coinciding with the cell width W on the surface 2a
of the substrate 2. That is, the controller 41 allows forming the
dots D sized in correspondence with the cell width W in the first
data cells C in direction +X.
[0073] Thereafter, the controller 41 operates to continuously
transport the substrate 2 in direction +X. Each time the ejection
target positions P reach the corresponding droplet receiving
positions PF, the controller 41 causes simultaneous ejection of the
droplets Fb from the selected nozzles N. Then, when each droplet Fb
reaches the size corresponding to the cell width W, the laser beams
B are radiated onto the zones corresponding to the droplets Fb. In
this manner, all of the necessary dots D are provided in the code
formation area S.
[0074] The first embodiment, which is configured as
above-described, has the following advantages.
[0075] The pivot stage 29 is provided in the carriage 27 and pivots
about the pivot axis coinciding with the droplet receiving position
PF. The pivot stage 29 includes the ejection head 32 and the laser
head 37. The droplets Fb are ejected from the nozzles N of the
ejection head 32 to the position PF in the ejecting direction A1.
The laser beams B radiates the ejected droplets Fb from the
ejection ports 38 of the laser head 37 to the position PF in the
radiating direction A2. In other words, the droplet receiving
position PF is located at the intersection of trajectory of the
droplets Fb from each nozzle N in direction A1 and optical axis of
the laser beam B irradiated from the corresponding radiation port
38 in direction A2.
[0076] Accordingly, when adjusting the radiation angle .theta.b of
each laser beam B, the position at which the droplet Fb is received
by the substrate 2 and the radiating position of the laser beam B
are maintained at the droplet receiving position PF. As a result,
the radiation angle .theta.b of each laser beam B is adjusted
independently, while maintaining the position accuracy of reception
of the ejected droplet Fb and that of radiation of the laser beam
B. This allows more flexible setting of the conditions for
radiating the laser beams B, thereby enhancing the controllability
for shaping the dots D formed by the droplets Fb. Further, by
pivoting the pivot stage 29 clockwise, the radiation angle .theta.b
of each laser beam B is decreased by the amount corresponding to
the pivot angle .theta.r. The optical axis of the laser beam B thus
approximates to the normal line of the substrate 2. This
correspondingly increases the energy density of the laser beam B
with respect to the corresponding droplet Fb. Insufficient drying
of the droplets Fb is thus avoided.
[0077] The pivot stage 29 is provided in the carriage 27.
Accordingly, the radiation angle .theta.b of each laser beam B may
be simply adjusted in any location on the surface 2a.
[0078] The laser head 37 and the ejection head 32 are secured
commonly to the pivot stage 29. Thus, the relative position between
the laser beam B and the ejection head 32 may be maintained.
Accordingly, in adjustment of the radiation angle .theta.b of the
laser beam B, the ejection head 32 can be maintained outside the
optical path of the laser beam B.
[0079] The illustrated embodiments may be modified as follows.
[0080] The radiation angle .theta.b may be set to zero degrees.
This maximizes the energy density of the laser beam B radiated onto
the corresponding droplet Fb. Insufficient drying of the droplets
Fb thus can be avoided further reliably.
[0081] Alternatively, the radiation angle .theta.b may be increased
by pivoting the pivot stage 29 counterclockwise. This enlarges the
optical cross section of the laser beam B radiated onto the
corresponding droplet Fb on the surface of the substrate and
decreases the energy density of the laser beam B. In this manner,
bumping of the droplet Fb caused by radiation of the laser beam B
is avoided. The droplet Fb is thus smoothly dried and baked.
[0082] Specifically, the pivot angle .theta.r may be set to any
suitable value in accordance with the conditions for drying the
droplets Fb.
[0083] Further, instead of securing the laser head 37 and the
ejection head 32 commonly to the pivot stage 29, the laser head 37
and the ejection head 32 may be secured separately to different
pivot stages. In this case, the pivot centers of the laser head 37
and the ejection head 32 commonly correspond to the ejection target
position P.
[0084] Instead of drying and baking the droplets Fb by the laser
beams B, the droplets Fb may be caused to flow in a desired
direction by the energy produced by the laser beams B.
Alternatively, the droplets Fb may be subjected to pinning by
restricting radiation of the laser beams B to the outer peripheral
portions of the droplets Fb. That is, any other suitable process
may be employed as long as marks are formed through radiation of
the laser beams B.
[0085] The marks formed with dots D are not restricted to the
semispherical shapes but may be modified to oval dots or a linear
mark.
[0086] Instead of the dots D of the identification code 10, the
mark may be embodied as different types of thin films, metal
wiring, or color filters of a liquid crystal display, an organic
electroluminescence display, or a field effect type device (an FED
or SED) having a flat electron emitting device. In other words, the
mark may be embodied in any other suitable forms as long as the
mark is provided through ejection of the droplets Fb. The field
effect type device emits light from a fluorescent substance by
radiating electrons emitted by the electron emitting device onto
the fluorescent substance.
[0087] The substrate 2 may be a silicone substrate, a flexible
substrate, or a metal substrate. The surface 2a onto which the
droplets Fb are ejected may be one of the surfaces of these
substrates. That is, the surface 2a may be any other suitable
surface as long as the surface is one of the surfaces of an object
on which a mark is formed through ejection of the droplets Fb.
[0088] Therefore, the present examples and embodiments are to be
considered as illustrative and not restrictive and the invention is
not to be limited to the details given herein, but may be modified
within the scope and equivalence of the appended claims.
* * * * *