U.S. patent application number 12/118278 was filed with the patent office on 2008-09-04 for sealant dispenser and control method thereof.
This patent application is currently assigned to Top Engineering Co., Ltd.. Invention is credited to Man Ho Ahn, Joon Young Kim.
Application Number | 20080210894 12/118278 |
Document ID | / |
Family ID | 36760392 |
Filed Date | 2008-09-04 |
United States Patent
Application |
20080210894 |
Kind Code |
A1 |
Ahn; Man Ho ; et
al. |
September 4, 2008 |
SEALANT DISPENSER AND CONTROL METHOD THEREOF
Abstract
Disclosed is a sealant dispenser for more precisely dispensing a
sealant onto a substrate, and a control method thereof. The sealant
dispenser includes a stage on which a substrate is mounted; a
nozzle for dispensing a sealant while making a relative motion with
the substrate; a syringe coupled to the nozzle, for storing the
sealant; and a distance sensor installed on both sides of a lower
portion of the syringe, for measuring a vertical distance between a
principal plane of the substrate and an outlet of the nozzle.
According to the principles of the present invention, because the
nozzle and the syringe have substantially the same central axis,
the response speed of the sealant to be dispensed is increased and
the start point and the end point of paste pattern are more
precisely dispensed. Also, by minimizing the distance between the
nozzle and a measuring point provided by the distance sensor, it
becomes possible to dispense the sealant at higher precision.
Inventors: |
Ahn; Man Ho; (Gumi-city,
KR) ; Kim; Joon Young; (Gumi-city, KR) |
Correspondence
Address: |
KED & ASSOCIATES, LLP
P.O. Box 221200
Chantilly
VA
20153-1200
US
|
Assignee: |
Top Engineering Co., Ltd.
|
Family ID: |
36760392 |
Appl. No.: |
12/118278 |
Filed: |
May 9, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11125528 |
May 10, 2005 |
|
|
|
12118278 |
|
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|
Current U.S.
Class: |
250/559.29 ;
118/669; 356/5.1 |
Current CPC
Class: |
B05C 11/1018 20130101;
G05B 2219/49362 20130101; B05C 5/0216 20130101; G05B 2219/45238
20130101 |
Class at
Publication: |
250/559.29 ;
356/5.1; 118/669 |
International
Class: |
G01C 3/08 20060101
G01C003/08 |
Foreign Application Data
Date |
Code |
Application Number |
May 12, 2004 |
KR |
2004-0033395 |
Claims
1. A sensor, comprising: a light emitting part that emits a beam of
light; a light receiving part that receives a portion of the beam
of light after it has been reflected from an interrogated surface,
wherein the light receiving part determines a distance from the
sensor to the interrogated surface, in part, based on a phase
difference of the received light as the sensor is moved relative to
the interrogated surface; and a supporting part that supports the
light emitting part and the light receiving part, wherein the light
emitting part and the light receiving part are positioned on
opposite sides of a syringe mounting portion that receives and
mounts a syringe of a sealant on the supporting part.
2. The sensor according to claim 1, wherein the supporting part is
arranged above the light receiving part and the light emitting
part.
3. The sensor according to claim 1, wherein the supporting part is
provided with a coupling hole between the light emitting part and
the light receiving part, and wherein the coupling hole is designed
to receive a syringe of a sealant.
4. The sensor according to claim 1, wherein the supporting part
comprises: a first support that supports the light emitting part;
and a second support that supports the light receiving part.
5. The sensor according to claim 1, wherein the light emitting part
and the light receiving part are separate elements that are each
installed on the supporting part.
6. The sensor according to claim 1, wherein the light emitting
part, the light receiving part, and the supporting part are
combined as one body.
7. The sensor according to claim 1, wherein the sensor is for use
with a sealant dispenser that includes a stage on which a substrate
is mounted and a syringe for dispensing a sealant while at least
one of the syringe and the stage are moved with respect to each
other, wherein the light emitting part and the light receiving part
are mounted on opposite sides of a syringe mounting portion of the
supporting part, and wherein the sensor measures a vertical
distance between the substrate and the syringe.
8. The sensor according to claim 7, wherein the supporting part is
arranged above the light emitting part and the light receiving
part, and wherein the supporting part comprises a coupling hole
that receives and mounts a syringe of a sealant between the between
the light emitting part and the light receiving part.
9. The sensor according to claim 7, wherein the coupling hole of
the supporting part mounts a syringe of sealant such that a central
axis of the syringe, and a central axis of a dispensing nozzle of
the syringe, are substantially aligned with the central axis of the
opening.
10. The sensor according to claim 7, wherein the light emitting
part and light receiving part are mounted on the supporting part
such that a central axis of the light beam emitted by the light
emitting part and a central axis of a direction of focus of the
light receiving part converge at a point adjacent to a location of
a nozzle of a syringe mounted in the coupling hole of the
support.
11. The sensor of claim 10, further comprising a position adjusting
device which operates to adjust a position of the syringe mounting
portion relative to the light emitting part and light receiving
part.
12. The sensor of claim 11, wherein the position adjusting device
maintains a minimum separation distance between a nozzle of a
syringe mounted in the syringe mounting portion and a measuring
point at which light from the light emitting part is reflected from
an interrogated surface located under the sensor.
13. The sensor according to claim 7, wherein a central axis of the
light beam emitted by the light emitting part and a central axis of
a direction of focus of the light receiving part converge at a
position located slightly to one side of a location of a nozzle of
a syringe mounted in the coupling hole of the support.
14. The sensor according to claim 1, wherein the light receiving
part outputs a signal that is indicative of a distance between the
supporting part and a substrate positioned below the sensor.
Description
RELATED APPLICATION
[0001] This application is a divisional of application Ser. No.
11/125,528 filed May 10, 2005, which claims priority to Korean
Patent Application No. 10-2004-0033395 filed May 12, 2004, the
contents of both are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates in general to a sealant
dispenser, and more specifically, to a sealant dispenser for more
precisely applying (or dispensing) a sealant onto a substrate, and
a control method thereof.
[0004] 2. Background of the Related Art
[0005] In general, liquid crystal display (LCD) is lighter and
smaller by volume than a traditional image display device using
cathode-ray tube (CRT). Therefore, making great strides in recent
years, LCD has been widely applied in many display devices, such as
computer monitors and TVs.
[0006] In case of the LCD, there is a certain space between an
upper substrate and a lower substrate, and the space is filled with
liquid crystal. In order for the LCD to perform its operation at
optimum state, a cell gap of the lower and upper substrates should
be maintained uniformly. In addition, in order to prevent excessive
liquid crystal dispensing or insufficient filling of the space, it
is very important to have a good positioning precision of a sealant
coating for sealing the upper and lower substrates, and a proper
control on the amount of coating being supplied to the substrates.
This is because if the cell gap is not uniform or if liquid crystal
is applied too much or insufficiently, the screen uniformity over
the entire screen of an LCD will be deteriorated.
[0007] A sealant used to seal the space between the lower and the
upper substrate not only maintains a uniform cell gap, but also
seals the upper and the lower substrate.
[0008] A sealant is applied to a substrate by means of a sealant
dispenser. The sealant dispenser includes a stage on which the
substrate is mounted, and a head unit provided with a nozzle for
discharging the sealant.
[0009] Here, the nozzle makes a relation motion to the substrate,
and applies a sealant of a designated shape onto the substrate. In
other words, the nozzle moves into X-axis and Y-axis directions
relatively to the substrate, and applies the sealant onto the
substrate. Also, the nozzle is movable into Z-axis direction to
adjust its height with respect to the substrate.
[0010] FIG. 1 illustrates a head unit of a related art sealant
dispenser.
[0011] As can be seen in the drawing, the head unit of the sealant
dispenser includes a syringe 20 for storing a sealant, and a nozzle
32 coupled to a lower portion of the syringe 20, for discharging
the sealant 50.
[0012] A long bar-shaped bracket 30 is connected to the syringe 20
in a horizontal direction, and the nozzle is installed on the end
of the bracket 30. And, a distance sensor 40 for measuring a
vertical distance between the nozzle 32 and the substrate 10 is
installed in the vicinity of the nozzle 32.
[0013] More specifically, the distance sensor 40 is spaced apart a
predetermined distance (L) from the syringe 20 which is filled with
the sealant. Here, the syringe 20 and the distance sensor 40 must
be installed in parallel because of their own volumes. Therefore,
in order to put the nozzle communicated with the syringe as close
as possible to the focal point of the distance sensor, the syringe
and the nozzle must be installed in `L` shape.
[0014] Usually, an optical laser distance sensor is used for the
distance sensor 40. The bottom surface of the distance sensor has a
"A", where a light emitting part 42 for emitting a laser beam 46 is
installed on one side and a light receiving part 44 for receiving a
laser beam 46 is on the other side.
[0015] Here, the light emitting part 42 emits a laser beam 46
towards the substrate, whereas the light receiving part 44 receives
the laser beam reflected from the substrate. As such, the distance
sensor 40 measures a distance between the substrate 10 and the
nozzle 32.
[0016] When the laser beam path is changed due to a flexure on the
sealant-applied surface of the substrate 10, the distance sensor
measures the laser beam received to the light receiving part and
transfers its measured value to a controller (not shown).
[0017] However, the related art sealant dispenser has the following
problems.
[0018] Firstly, since the nozzle and the syringe are spaced a
designated distance apart, the flow path of the sealant is bent in
"L" shape. In detail, the distance sensor and the syringe of the
related sealant dispenser are separately installed in the head unit
while maintaining a designated distance from each other. This is
why the flow path of the sealant has an "L" shape.
[0019] In that light, the related art dispenser requires a high
pressure for discharging the sealant, and the usage of a highly
viscous sealant was limited.
[0020] Secondly, according to the related art sealant dispenser,
the nozzle is installed on the lower portion of the bracket, so
that there is a great distance between the position on the
substrate where the sealant is discharged and the position on the
substrate where a laser beam is reflected. Therefore, the distance
sensor cannot get an accurate a vertical distance from the point to
which the sealant is actually discharged to the nozzle.
[0021] Thirdly, since the flow path of the sealant in the related
art sealant dispenser is in "L" shape, the sealant is relatively
slowly discharged. Hence, it is not clear exactly where sealant
dispensing starts and ends.
SUMMARY OF THE INVENTION
[0022] Accordingly, the present invention is directed to a lighting
optical system that substantially obviates one or more problems due
to limitations and disadvantages of the related art.
[0023] An object of the present invention is to provide a sealant
dispenser featuring a low pressure for dispensing the sealant, and
a control method thereof.
[0024] Another object of the present invention is to provide a high
precision sealant dispenser and a control method thereof.
[0025] Still another object of the present invention is to provide
a sealant dispenser featuring an accurate control over the
dispensing position and dispensing amount of a sealant by
increasing the response speed of a sealant to be dispensed, and a
control method thereof.
[0026] Additional advantages, objects, and features of the
invention will be set forth in part in the description which
follows and in part will become apparent to those having ordinary
skill in the art upon examination of the following or may be
learned from practice of the invention. The objectives and other
advantages of the invention may be realized and attained by the
structure particularly pointed out in the written description and
claims hereof as well as the appended drawings.
[0027] To achieve these objects and other advantages and in
accordance with the purpose of the invention, as embodied and
broadly described herein, there is provided a sealant dispenser,
including: a stage on which a substrate is mounted; a nozzle for
dispensing a sealant while making a relative motion with the
substrate; a syringe coupled to the nozzle, for storing the
sealant; and a distance sensor installed on both sides of a lower
portion of the syringe, for measuring a vertical distance between a
principal plane of the substrate and an outlet of the nozzle.
[0028] Preferably, the distance sensor includes: a light emitting
part for emitting a laser beam towards the substrate; a light
receiving part for receiving a laser beam reflected form the
substrate; and a sensor supporting part for supporting the light
emitting part and the light receiving part.
[0029] Preferably, the sensor supporting part includes a coupling
hole that the nozzle passes through.
[0030] More preferably, the coupling hole is disposed between the
light emitting part and the light receiving part.
[0031] Preferably, the syringe and the outlet of the nozzle have
substantially the same central axis.
[0032] More preferably, a focal point of a laser beam emitted form
the distance sensor, the nozzle, and the syringe are arranged on
the same axis
[0033] Preferably, the light emitting part and the light receiving
part of the distance sensor are aligned in a straight line along
the principal plane of the substrate, and the light emitting part
and the light receiving part are combined as one body.
[0034] Preferably, the vertical distance between the substrate and
the nozzle is maintained at a constant value.
[0035] Another aspect of the present invention provides a sealant
dispenser, including: a stage on which a substrate is mounted; a
nozzle for dispensing a sealant while making a relative motion with
the substrate; a distance sensor for measuring a vertical distance
between a principal plane of the substrate and an outlet of the
nozzle; and a position detecting sensor for detecting a horizontal
position of the nozzle on the principal surface of the
substrate.
[0036] Preferably, the position detecting sensor and the nozzle are
located each other at the opposite sides with respect to the
substrate.
[0037] Preferably, the sealant dispenser further includes an
adjusting part for adjusting the position of a syringe storing the
sealant.
[0038] Preferably, a measuring point on the principal plane of the
substrate in which a laser beam from the distance sensor is
reflected is disposed on a front end of the nozzle along the
direction of the sealant application.
[0039] More preferably, the nozzle and the measuring point maintain
a minimum distance from each other so that the laser beam does not
interfere with the sealant.
[0040] Still another aspect of the present invention provides a
control method of a sealant dispenser, which the method includes
the steps of: in a position detecting sensor installed below a
substrate, setting a horizontal position of a nozzle on a principal
plane of the substrate; in a distance sensor installed on both
sides of a lower portion of a syringe, setting a vertical distance
between the substrate and the nozzle; and dispensing a sealant to
the position being set.
[0041] Preferably, the step for setting the horizontal position of
the nozzle includes the sub-steps of: measuring a horizontal
distance between a measuring point on the substrate in which a
laser beam is reflected and the nozzle; and deciding whether the
measured horizontal distance falls within a predetermined allowable
range.
[0042] Preferably, the method further includes the step of: if the
measured horizontal distance is outside the allowable range,
revising the horizontal position of the nozzle.
[0043] Preferably, the step for setting the vertical distance
between the substrate and the nozzle includes the sub-steps of:
measuring a vertical distance between the substrate and the nozzle;
and deciding whether the measured vertical distance falls within a
predetermined allowable range.
[0044] Preferably, the method further includes the step of: if the
measured vertical distance is outside the allowable range, revising
the vertical distance between the nozzle and the substrate.
[0045] Preferably, the vertical distance between the substrate and
the nozzle is revised to maintain a constant value.
[0046] Preferably, the syringe and the nozzle for dispensing the
sealant to the principal plane of the substrate have substantially
the same central axis.
[0047] It is to be understood that both the foregoing general
description and the following detailed description of the present
invention are exemplary and explanatory and are intended to provide
further explanation of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0048] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this application, illustrate embodiment(s) of
the invention and together with the description serve to explain
the principle of the invention. In the drawings:
[0049] FIG. 1 is a perspective view illustrating a head unit of a
related art sealant dispenser;
[0050] FIG. 2 is a front view illustrating key elements of a
sealant dispenser according to the present invention;
[0051] FIG. 3 is a side view of a key element taking in the
direction of arrow A in FIG. 2;
[0052] FIG. 4 illustrates a detected position of a distance sensor
photographed by a position detecting sensor, and a location of a
nozzle; and
[0053] FIG. 5 is a flow chart explaining a control method of a
sealant dispenser according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0054] Reference will now be made in detail to the preferred
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings.
[0055] FIG. 2 is a front view illustrating key elements of a
sealant dispenser according to the present invention; FIG. 3 is a
side view of a key element taking in the direction of arrow A in
FIG. 2; and FIG. 4 illustrates a detected position of a distance
sensor which is photographed by a position detecting sensor, and a
location of a nozzle.
[0056] Referring to FIG. 2 to 4, the sealant dispenser of the
present invention includes a nozzle 130 for discharging a sealant
while making a relative motion to a substrate 110 mounted on a
stage, a syringe 120 coupled to the nozzle 130, for storing the
sealant, and a distance sensor 140 installed on both sides of the
lower portion of the syringe 120, for measuring a vertical distance
from the principal plane of the substrate 110 to an outlet of the
nozzle 130.
[0057] The syringe 120 for storing a sealant is in conical shape of
which the inside diameter decreases in the downward direction, and
is installed perpendicularly to the surface of the substrate 110.
Also, the nozzle 130 is coupled to one end of the syringe 120, and
the outlet of the nozzle 130 is installed in such a manner to have
substantially the same central axis with the syringe 120.
[0058] The sealant 150 in the syringe 120 travels along a straight
flow path and is discharged from the nozzle. In result, the
response speed of the sealant is increased according to a positive
or negative pressure signal of a controller that controls the
amount of the sealant to be applied, and the sealant can be applied
to an accurate position on the substrate. Especially, since the
start point and the end point of dispensing are set precisely,
defect rate can be reduced markedly.
[0059] The distance sensor 140 includes a light emitting part 142
for emitting a laser beam toward the substrate 110, a light
receiving part 144 for receiving a reflected laser beam from the
substrate 110, and a sensor supporting part 145 for supporting the
light emitting part 142 and the light receiving part 144.
[0060] The sensor supporting part 145 is installed above the light
emitting part 142 and the light receiving part 144, encompassing
the lower portion of the syringe 120. And, the sensor supporting
part 145 is provided with a coupling hole 148 between the light
receiving part 144 and the light emitting part 142, so that the
nozzle 130 passing through the coupling hole 148 is located between
the light receiving part 144 and the light emitting part 142.
[0061] Optionally, the sensor supporting part 145 can have a first
sensor support supporting the light receiving part 144 and a second
sensor support supporting the light emitting part 142. That is, the
light receiving part 144 and the light emitting part 142 are
separately installed on both sides of the lower portion of the
syringe, and the lower portion of the syringe mounted with the
nozzle is installed between the light receiving part 144 and the
light emitting part 142.
[0062] Apart from the above constitutional elements, the present
invention also includes a head unit structure in which the focal
point of a laser beam emitted form the distance sensor, the nozzle,
and the syringe are serially arranged on the same axis.
[0063] As can be seen in FIG. 3, the light emitting part and the
light receiving part of the distance sensor 140, and the syringe
120 are aligned in parallel to the principal surface of the
substrate. In detail, if seen in the direction of arrow A in FIG.
2, the distance sensor 140 is installed symmetrically around the
center of the syringe.
[0064] Preferably, the light emitting part 142 and the light
receiving part 144 of the distance sensor 140 are combined as one
body. However, this is for illustrative purposes only and the
present invention is not limited thereto. As aforementioned,
therefore, it is possible to install the light transmitting part
and the light receiving part separately from each other, and put
the nozzle therebetween.
[0065] The distance sensor 140 measures a vertical distance between
the nozzle 130 and the substrate 110 to which the sealant 150 is
applied. To this end, the light emitting part 142 of the distance
sensor 140 emits a laser beam towards the substrate 110, and the
light receiving part 144 receives a reflected laser beam from the
substrate 110.
[0066] If the vertical distance between the substrate 110 and the
nozzle 130 is changed due to a flexure on the surface of the
substrate 110, the height from a point of laser beam reflection is
changed. Consequently, not only the laser beam is received at a
different position on the light receiving part 144, but also the
phase of the laser beam is changed. Based on these changes, the
distance sensor 140 measures the vertical distance from the nozzle
130 and the substrate 110.
[0067] The measured vertical distance between the nozzle 130 and
the substrate 110 is sent to a controller (not shown). Then, the
controller (not shown) moves the nozzle 130 and the substrate 110
relatively to each other until the vertical distance has a
predetermined value. Examples of a driving means (not shown) for
moving the substrate and the nozzle include a linear motor and a
servomotor.
[0068] Meanwhile, as shown in FIG. 2, a measuring point 112 on the
substrate 110 from which a laser beam 146 is reflected is disposed
a predetermined distance away from a position where the sealant 150
is applied. If the measuring point 112 and the position to which
the sealant 150 is applied are coincident, the distance sensor 140
is interfered with its distance measurement by the sealant 150
applied to the substrate 110. Thus, it is important that the
measuring point 112 and the nozzle 130 are spaced apart at least at
a minimum distance for the sealant not to interfere with the laser
beam. Moreover, the measuring point 112 is preferably located on a
front end of the nozzle, along the direction of the sealant
application.
[0069] However, the above-described embodiments are merely
exemplary and are not to limit the present invention. In effect,
the measuring point and the position to which the sealant is
applied can be located within a predetermined allowable range.
Also, the measuring point can be located in any position close to
the nozzle, along the direction of the sealant application.
[0070] Furthermore, a position detecting sensor 170 is installed
below the substrate 110 and detects a horizontal distance between
the nozzle 130 and the measuring point in which the laser beam
emitted from the distance sensor 140 is reflected. Precisely
speaking, the position detecting sensor 170 and the nozzle 130 are
located at the opposite sides with respect to the substrate
110.
[0071] Although a camera is preferably used as the position
detecting sensor 170, any type of sensor capable of detecting the
position of the nozzle and the measuring point can be utilized.
[0072] As depicted in FIG. 4, a screen 175 photographed by the
position detecting sensor 170 displays the nozzle and the measuring
point.
[0073] Since the substrate 110 coated with the sealant 150 is a
transparent glass, the measuring point 112 and the nozzle 130 are
projected onto the substrate 110. Hence, the position detecting
sensor 170 regards a position on the substrate 110 where the nozzle
130 is projected as a place where the sealant 150 should be
applied, and detects a distance d between the measuring point 112
and the nozzle 130.
[0074] If the distance d between the measuring point 112 and the
nozzle 130 is outside the predetermined allowable range, an
adjusting part 160 mounted on the head unit adjusts the position of
the syringe coupled to the nozzle.
[0075] Actually, the adjusting part 160 is connected to the syringe
and minutely adjusts the coupling position of the syringe. The
adjusting part 160 includes a motor to be able to adjust the
coupling position and angle of the syringe 120.
[0076] Alternatively, if the nozzle is stopped, a stage (not shown)
supporting the substrate can be driven to adjust the horizontal
distance between the nozzle and the substrate.
[0077] FIG. 5 is a flow chart explaining a control method of the
sealant dispenser according to the present invention. The control
method of the sealant dispenser will now be described in greater
detail below.
[0078] As can be seen in FIG. 5, the control method of the sealant
dispenser is largely divided into three steps: a first set-up step
(S100) performed by the position detecting sensor, for setting or
specifying a horizontal position of the nozzle on the principal
plane of the substrate; a second set-up step (S200) performed by
the distance sensor, for setting a vertical distance between the
substrate and the nozzle; and a sealant dispensing step (S300) for
dispensing or applying a sealant to the position set in the first
and second steps.
[0079] In the first set-up step (S100), when the syringe descends,
the nozzle coupled to the syringe moves close to the surface of the
substrate. Here, it is also acceptable for the nozzle to touch the
surface of the substrate.
[0080] Then, the position detecting sensor installed below the
substrate photographs the measuring point on the substrate in which
the laser beam reflects and the position of the nozzle, to detect
the horizontal distance between the measuring point and the nozzle
(S110).
[0081] Once the horizontal distance between the nozzle and the
measuring point is detected, it is decided whether the measured
horizontal distance is within the predetermined allowable range
(S130).
[0082] Here, the allowable range indicates a user-specified range
for an appropriate distance between the measuring point and the
nozzle. Preferably, the allowable range is set up differently,
depending on a kind of the sealant used and pressure/speed of
dispensing the sealant.
[0083] If a result of the first decision in step S130 tells that
the distance between the measuring point and the nozzle is within
the allowable range, the method proceeds to a second set-up step
for setting the vertical distance between the nozzle and the
substrates (S200).
[0084] On the other band, if the horizontal distance between the
measuring point and the nozzle is outside the allowable range, the
position of the nozzle is revised (S150). In this revision step,
the adjusting part mounted on the head unit revises the position of
the syringe to make sure that the horizontal distance between the
measuring point and the nozzle falls within the allowable range.
After revising the position of the syringe, it is preferable to
measure the horizontal distance between the measuring point and the
nozzle again.
[0085] When the first set-up step (S100) for setting the horizontal
position of the nozzle on the surface of the substrate is over, the
method proceeds to the second set-up step (S200) for setting the
horizontal distance between the substrate and the nozzle.
[0086] In the second set-up step (S200), the distance sensor on the
circumference of the lower portion of the syringe measures the
vertical distance between the substrate and the nozzle (S210).
Because the procedure associated with the measurement of the
vertical distance has been already described referring to the
constitutional elements of the distance sensor, it will not be
explained here.
[0087] Once the vertical distance is measured, it is decided as a
second decision step whether the measured vertical distance falls
within the allowable range (S230). If a result of the second
decision tells that the vertical distance is within the allowable
range, the sealant is discharged (dispensed) through the outlet of
the nozzle (S300).
[0088] However, if a result of the second decision tells that the
vertical distance is outside the allowable range, the vertical
distance between the nozzle and the substrate is revised
(S250).
[0089] In the revision step S250, either the syringe coupled to the
nozzle can be moved vertically with respect to the surface of the
substrate, or the other way round (i.e., the substrate can be moved
vertically with respect to the nozzle). Either way, the vertical
distance between the substrate and the nozzle must maintain a
constant value.
[0090] When the vertical distance between the nozzle and the
substrate falls within the allowable range through the revision,
the sealant is discharged (or dispensed) through the outlet of the
nozzle (S300). During the sealant dispensing step (S300), the
syringe and the nozzle dispense the sealant while moving around
substantially the same pivot.
[0091] The sealant dispenser and its control method have the
following advantages.
[0092] Firstly, the syringe and the nozzle have substantially the
same pivot according to the principles of the present invention, so
that the flow path of the sealant becomes a straight line, which in
turn lowers the pressure required for discharging (or dispensing)
the sealant. This means that diverse kinds of sealants including a
highly viscous sealant can be utilized.
[0093] Secondly, the distance between the measuring point on the
substrate in which the laser beam is reflected and the position to
which the sealant is applied is minimized, so that the sealant can
be applied more precisely.
[0094] Thirdly, since the flow path of the sealant is a straight
line, the response speed of the sealant to be dispensed is
increased. Thus, a precise amount of the sealant can be applied to
an accurate position. Especially, by setting the start point and
the end point of dispensing more precisely, the defect rate is
reduced markedly.
[0095] Fourthly, by setting the distance between the nozzle and the
distance sensor within the allowable range, the application of the
sealant can be controlled more precisely, and replacement of the
syringe can be done easily and quickly.
[0096] The forgoing embodiments are merely exemplary and are not to
be construed as limiting the present invention. The present
teachings can be readily applied to other types of apparatuses. The
description of the present invention is intended to be
illustrative, and not to limit the scope of the claims. Many
alternatives, modifications, and variations will be apparent to
those skilled in the art.
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