U.S. patent application number 13/383855 was filed with the patent office on 2012-05-10 for device and method for processing substrate, and method for producing a processed substrate.
This patent application is currently assigned to Sharp Kabushiki Kaisha. Invention is credited to Yasufumi Mizukami, Takenori Yoshizawa.
Application Number | 20120115399 13/383855 |
Document ID | / |
Family ID | 43449088 |
Filed Date | 2012-05-10 |
United States Patent
Application |
20120115399 |
Kind Code |
A1 |
Yoshizawa; Takenori ; et
al. |
May 10, 2012 |
DEVICE AND METHOD FOR PROCESSING SUBSTRATE, AND METHOD FOR
PRODUCING A PROCESSED SUBSTRATE
Abstract
Disclosed are a simple device for processing substrate which can
make a surface of a processed substrate smooth, a method for
processing substrate with the use of the processing device, and a
method for producing a processed substrate with the use of the
processing method. The device of the present invention for
processing a substrate includes a jetting member (12) provided so
that a jetting angle of abrasive grains (12a) with respect to a
processed surface of the substrate (1) becomes an angle for
brittleness processing, the jetting member (12) jetting the
abrasive grains (12a); and a jetting direction changing member (18)
provided between the jetting member (12) and the processed surface
of the substrate (1) in a jetting direction of the abrasive grains
(12a), the jetting direction changing member (18) changing an angle
at which the abrasive grains (12a) enter the processed surface of
the substrate (1) from the angle for the brittleness processing to
an angle for ductility processing, the jetting direction changing
member (18) being movable.
Inventors: |
Yoshizawa; Takenori; (Osaka,
JP) ; Mizukami; Yasufumi; (Tokyo, JP) |
Assignee: |
Sharp Kabushiki Kaisha
Osaka
JP
|
Family ID: |
43449088 |
Appl. No.: |
13/383855 |
Filed: |
March 26, 2010 |
PCT Filed: |
March 26, 2010 |
PCT NO: |
PCT/JP2010/002197 |
371 Date: |
January 13, 2012 |
Current U.S.
Class: |
451/38 ;
451/91 |
Current CPC
Class: |
B24C 1/04 20130101; B24C
3/04 20130101; B24C 3/02 20130101 |
Class at
Publication: |
451/38 ;
451/91 |
International
Class: |
B24C 1/00 20060101
B24C001/00; B24C 5/00 20060101 B24C005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 15, 2009 |
JP |
2009-167110 |
Claims
1. A device for processing a substrate, comprising: a jetting
member provided so that a jetting angle of abrasive grains with
respect to a processed surface of the substrate becomes an angle
for brittleness processing, the jetting member jetting the abrasive
grains; and a jetting direction changing member provided between
the jetting member and the processed surface of the substrate in a
jetting direction of the abrasive grains, the jetting direction
changing member changing an angle at which the abrasive grains
enter the processed surface of the substrate from the angle for the
brittleness processing to an angle for ductility processing, the
jetting direction changing member being movable.
2. The device according to claim 1, further comprising a rotating
member for rotating the jetting direction changing member around a
normal to the processed surface which normal passes through the
jetting direction changing member.
3. The device according to claim 1, further comprising a jetting
direction controlling member for controlling an angle of the
jetting direction changing member with respect to a normal to the
processed surface which normal passes through the jetting direction
changing member.
4. The device according to claim 1, wherein the jetting direction
changing member contains at least one of silicon carbide and
silicon nitride.
5. The device according claim 1, wherein: the substrate is a glass
substrate, and the abrasive grains are made of alumina.
6. The device according to claim 1, wherein (i) jetting of the
abrasive grains and a medium for jetting the abrasive grains and
(ii) jetting of only the medium are alternately carried out.
7. The device according to claim 1, wherein a processed portion of
the substrate is filled with a transparent material.
8. The device according to claim 1, wherein the substrate is for
constituting a liquid crystal display panel.
9. A method for processing a substrate with use of a device as set
forth in claim 1, comprising the steps of: performing brittleness
processing with respect to the substrate; and performing ductility
processing with respect to the substrate after the brittleness
processing.
10. A method for producing a processed substrate, comprising the
step of using the method as set forth in claim 9.
Description
TECHNICAL FIELD
[0001] The present invention relates to device and method for
processing a substrate, and a method for producing a processed
substrate. More specifically, the present invention relates to a
simple device for processing a substrate which allows a processed
substrate to have a smooth surface (mirror surface), a method for
processing a substrate with the use of the processing device, and a
method for producing a processed substrate with the use of the
processing method.
BACKGROUND ART
[0002] Conventionally, as means for remedying a defect of a
substrate, substrate processing such as blast processing has
generally been performed to form a recess on a substrate
surface.
[0003] For example, a glass substrate is required to meet a demand
for a reduction in glass substrate defect, which demand arises as a
result of a recent increase in display screen size. What is meant
by the term "glass substrate defect" is an internal defect such as
an internal bubble or an internal foreign matter, and a surface
defect such as a protrusion or a scratch formed on a surface of the
glass substrate.
[0004] A flat display produced with the use of a glass substrate
having a defect suffers a display defect such as a bright dot or a
black dot in the vicinity of the defect. For example, in a case
where an internal bubble having a certain degree of size (e.g.,
diameter of 100 .mu.m or more) is present, the vicinity of the
bubble is observed as a bright dot. Although it is necessarily not
clear how an internal bubble causes a bright dot, it can be
hypothesized that, because the internal bubble exists, a lens
effect is caused due to a glass around the internal bubble, or a
scattered polarization state is caused due to a residual stress of
the glass around the internal bubble, thereby causing such a bright
dot. Further in a case where an internal foreign matter having a
certain degree of size exists in a glass substrate, and the
internal foreign matter is made of a light-shielding material, a
black dot may occur. Furthermore, in a case of a surface defect
such as a protrusion or a scratch, a minute refracting surface or
reflecting surface that is different from the original surface of
the glass substrate is formed. As a result, a bright dot due to
them can occur. It is therefore preferable that a glass substrate
include as little defects as possible.
[0005] The following description deals with how a defect of a glass
substrate occurs.
[0006] In a process of melting a glass material in producing a
glass substrate, air comes into the material or a gas is emitted
from a fire-resisting material, thereby causing a bubble in the
melted glass material. Thus, an internal bubble is caused. Further,
there are some glass materials to be used that generate a gas
themselves. Such internal bubbles exist at a certain ratio
depending on a volume, and it is not easy to decrease the ratio. In
a case where a bubble existing inside a glass substrate is located
close to a surface of the glass substrate, the glass substrate may
include a protrusion (including a projection or an undulation) on
the surface thereof.
[0007] An internal foreign matter is caused due to (i) a raw
material, or (ii) contamination from outside. The internal foreign
matter caused due to a raw material includes (a) a case where a
glass material is not melted and remains as a foreign matter, and
(b) a case where a material that is not easily melted is mixed in a
glass material. Further, the contamination from outside includes a
case where a fire-resisting material that has been used for melting
a glass material is mixed in the glass material and remains as a
foreign matter. In a case where such a foreign matter existing
inside the glass substrate is located close to a surface of the
substrate, the glass substrate may include a protrusion (including
a projection or an undulation) on the surface of the glass
substrate, similarly to the internal bubble.
[0008] A protrusion formed on the surface of the glass substrate
is, as has been already described, a surface defect that is caused
due to an internal bubble or internal foreign matter.
[0009] Further, a scratch formed on the surface of the glass
substrate is caused such that, in a processing step of carrying out
an edge process with respect to glass substrates cut out from a
large glass plate, which is called a primitive plate, the glass
substrates come into contact with each other.
[0010] Here, though this is not the one for dealing with the glass
substrate defects, there has been known a technique for eliminating
a bright dot defect, in which technique a recess is formed on a
region corresponding to a defective pixel in a glass substrate, and
a light-shielding resin is filled into the recess, so that leakage
of light is prevented (see Patent Literatures 1 and 2, for
example).
[0011] Further, there has been also known a polishing apparatus for
removing a very small protrusion by grinding the protrusion formed
in a color filter of a liquid crystal display panel (see, for
example, Patent Literature 3).
CITATION LIST
[0012] Patent Literature 1
[0013] Japanese Patent Application Publication, Tokukaihei, No.
5-210074 A (Publication Date: Aug. 20, 1993)
[0014] Patent Literature 2
[0015] Japanese Patent Application Publication, Tokukai, No.
2005-189360 A (Publication Date: Jul. 14, 2005)
[0016] Patent Literature 3
[0017] Japanese Patent Application Publication, Tokukaihei, No.
6-313871 A (Publication Date: Nov. 8, 1994)
SUMMARY OF INVENTION
Technical Problem
[0018] However, the conventional substrate processing method has a
problem that it is difficult to remedy a defect of a substrate.
[0019] Although it is ideal to use a glass substrate having no
defect, it is impossible to produce such a substrate. Further, even
if the occurrence of defects can be reduced to a certain degree by
improving a production process of a substrate, there is a
limit.
[0020] On the other hand, in a case where all glass substrates
including defects are regarded as defective products, problems such
as a reduction in production yield and an increase in cost of a
substrate arise. Especially in a large glass substrate for a large
display, the reduction in production yield is a serious problem
because the large glass substrate is stochastically likely to
include such a defect.
[0021] From these reasons, a technique in which, even if a produced
glass substrate includes a defect, the defect is remedied so that a
good-quality product is produced, is required.
[0022] Such a requirement for the technique is common for general
substrates such as glass substrates that constitute a flat display
panel such as a liquid crystal display panel or a plasma display
panel. From the following reason, the technique is more
significantly required for the glass substrate for a liquid crystal
display panel.
[0023] In the glass substrate for a liquid crystal display panel,
it is necessary to provide a semiconductor element on its surface,
and the semiconductor element easily receives a bad influence from
an alkali metal. From this reason, it is general to use, as the
glass substrate for a liquid crystal display panel, a non-alkali
glass that does not include the alkali metal as an additive
component (the alkali metal as an impurity is not more than 1%).
However, since a melting point of the non-alkali glass is high, in
a case where the non-alkali glass is used, while a glass material
is melted, a bubble does not easily come out from the material,
thereby resulting in that the bubble tends to remain inside as an
internal bubble. As such, the glass substrate for a liquid crystal
display panel tends to include a defect as the internal bubble. In
view of this, the technique for producing a good-quality product by
remedying such a defect is particularly highly required for the
glass substrate for a liquid crystal display panel.
[0024] Further, as a technique for solving the above problem, there
is a technique of performing brittleness processing to remove, from
a substrate, a material in a region including a defect to be
remedied by jetting at least one of powder and fluid toward a
portion where the defect is located.
[0025] However, the technique of performing brittleness processing
has a problem that a surface of a processed substrate cannot be
made smooth.
[0026] In order to make a surface of a processed substrate smooth,
it may be possible to perform ductility processing after performing
brittleness processing, i.e., switch processing from the
brittleness processing to ductility processing. However, switching
the processing from the brittleness processing to ductility
processing by moving a member for jetting powder or fluid causes a
new problem that a processing device becomes complicated and
large.
[0027] The present invention was attained in view of the above
problems, and an object of the present invention is to provide a
simple device for processing a substrate which allows a processed
substrate to have a smooth surface, a method for processing a
substrate with the use of the processing device, and a method for
producing a processed substrate with the use of the processing
method.
Solution to Problem
[0028] In order to attain the above object, a device of the present
invention for processing a substrate, includes: a jetting member
provided so that a jetting angle of abrasive grains with respect to
a processed surface of the substrate becomes an angle for
brittleness processing, the jetting member jetting the abrasive
grains; and a jetting direction changing member provided between
the jetting member and the processed surface of the substrate in a
jetting direction of the abrasive grains, the jetting direction
changing member changing an angle at which the abrasive grains
enter the processed surface of the substrate from the angle for the
brittleness processing to an angle for ductility processing, the
jetting direction changing member being movable.
[0029] According to the arrangement, the jetting direction changing
member is disposed between the jetting member and the processed
surface of the substrate in the jetting direction of the abrasive
grains. This makes it possible to change the angle at which the
abrasive grains enter the processed surface of the substrate from
the angle for the brittleness processing to the angle for the
ductility processing. This allows the substrate to have a smooth
surface after the processing. Furthermore, according to the
arrangement, the jetting direction changing member is movable. This
makes it possible to change the angle at which the abrasive grains
enter the processed surface of the substrate from the angle for the
ductility processing to the angle for the brittleness processing
again. Specifically, by moving the jetting direction changing
member to a position which does not make contact with the abrasive
grains, the angle at which the abrasive grains enter the processed
surface of the substrate can be changed from the angle for the
ductility processing to the angle for the brittleness processing
again.
[0030] Furthermore, according to the arrangement, only one jetting
member is needed to change the angle at which the abrasive grains
enter the processed surface of the substrate from the angle for the
brittleness processing to the angle for the ductility processing
and from the angle for the ductility processing to the angle for
the brittleness processing. This makes it possible to make the
device for processing a substrate simple.
Advantageous Effects of Invention
[0031] As described above, a device of the present invention for
processing a substrate includes: a jetting member provided so that
a jetting angle of abrasive grains with respect to a processed
surface of the substrate becomes an angle for brittleness
processing, the jetting member jetting the abrasive grains; and a
jetting direction changing member provided between the jetting
member and the processed surface of the substrate in a jetting
direction of the abrasive grains, the jetting direction changing
member changing an angle at which the abrasive grains enter the
processed surface of the substrate from the angle for the
brittleness processing to an angle for ductility processing, the
jetting direction changing member being movable.
[0032] Consequently, the substrate processing device of the present
invention makes it possible to make a surface of a processed
substrate smooth with a simple structure.
BRIEF DESCRIPTION OF DRAWINGS
[0033] FIG. 1
[0034] FIG. 1 is a cross-sectional view showing how a grinding
process in Embodiment 1 of the present invention progresses.
[0035] FIG. 2
[0036] FIG. 2 is a cross-sectional view illustrating a substantial
part of a glass substrate to be remedied in Embodiment 1 of the
present invention.
[0037] FIG. 3
[0038] FIG. 3 is an explanatory view illustrating a defect
remedying device used in Embodiment 1 of the present invention, (a)
of FIG. 3 is a cross-sectional view illustrating a configuration of
the defect remedying device, (b) of FIG. 3 is a plan view
illustrating a substantial part of the defect remedying device, and
(c) of FIG. 3 is a cross-sectional view illustrating a substantial
part of the defect remedying device.
[0039] FIG. 4
[0040] FIG. 4 is a cross-sectional view illustrating a remedying
head provided in the defect remedying device shown in FIG. 3.
[0041] FIG. 5
[0042] FIG. 5 is a cross-sectional view illustrating a shape of a
processed surface obtained by the grinding process.
[0043] FIG. 6
[0044] FIG. 6 is a cross-sectional view illustrating a state where
a recess formed by the grinding process is filled with a
transparent material.
[0045] FIG. 7
[0046] FIG. 7 is a cross-sectional view illustrating a substantial
part of another glass substrate to be remedied in Embodiment 1 of
the present invention.
[0047] FIG. 8
[0048] FIG. 8 is a cross-sectional view illustrating a substantial
part of a glass substrate to be remedied in Embodiment 2 of the
present invention.
[0049] FIG. 9
[0050] FIG. 9 is a cross-sectional view showing how a grinding
process in Embodiment 2 of the present invention progresses.
[0051] FIG. 10
[0052] FIG. 10 is a cross-sectional view illustrating a substantial
part of a glass substrate to be remedied in Embodiment 3 of the
present invention.
[0053] FIG. 11
[0054] FIG. 11 is a cross-sectional view showing how a grinding
process in Embodiment 3 of the present invention progresses.
[0055] FIG. 12
[0056] FIG. 12 is an explanatory view illustrating a liquid crystal
display panel in an embodiment of the present invention, (a) of
FIG. 12 is a plan view illustrating the liquid crystal display
panel, and (b) of FIG. 12 is a cross-sectional view illustrating
the liquid crystal display panel.
[0057] FIG. 13
[0058] FIG. 13 is a cross-sectional view illustrating a
configuration of another defect remedying device used in a defect
remedying method of the present invention.
[0059] FIG. 14
[0060] FIG. 14 is a cross-sectional view illustrating another
remedying head used in a defect remedying method of the present
invention.
[0061] FIG. 15
[0062] FIG. 15 is a diagram illustrating an appearance of a surface
of a glass substrate achieved before and after a grinding process
in the defect remedying method of the present invention is carried
out, (a) of FIG. 15 illustrates an appearance of the surface of the
glass substrate achieved before the grinding process is carried
out, and (b) of FIG. 15 illustrates an appearance of the surface of
the glass substrate achieved after the grinding process is carried
out. Note that the appearance of the surface of the glass substrate
achieved before and after the grinding process is carried out was
photographed with the use of a general digital camera having
resolution of six million pixels.
DESCRIPTION OF EMBODIMENTS
Embodiment 1
[0063] Embodiment 1 of the present invention is described below.
Note that the present invention is not limited to this. Dimensions,
materials, shapes, relative positions of constituent members
described in the present embodiment are merely examples, and the
scope of the present invention is not limited to these, unless
otherwise specified. In the present specification etc., what is
meant by the expression "A to B" indicative of a range is "not less
than A and not more than B".
[0064] The present embodiment deals with, as examples of device and
method for processing a substrate, device and method for remedying
a defect of a glass substrate. Note, however, that the present
invention is not limited to these, and can be applied also to
device and method for processing a general substrate
(material).
[0065] A substrate (material) to be processed is not limited to a
specific one, provided that it is a brittle material. Examples of
the substrate (material) to be processed include glass, ceramics,
and the like.
[0066] A defect remedying method of the present embodiment is a
defect remedying method for a glass substrate which will constitute
a display panel, and a defect to be remedied is an internal defect
formed in a glass substrate.
[0067] The defect remedying method of the present embodiment can be
applied to a glass substrate which will constitute various display
panels such as a liquid crystal display panel, a plasma display
panel (PDP), and the like.
[0068] Further, the defect remedying method of the present
embodiment can be carried out in various stages in producing a
glass substrate or a display panel. That is, the defect remedying
method of the present embodiment can be carried out, for example:
(i) in a stage where a glass substrate has been cut out from a
primitive plate by a glass manufacturer but has not been shipped
yet; (ii) in a stage where the glass substrate has been received by
a manufacturer of a display device but has not been used in a
display panel yet; and (iii) in a stage where a display panel
constituted by use of the glass substrate has been checked but has
not been assembled as a display device yet. Especially, in the case
where the defect remedying method of the present embodiment is
carried out with respect to a glass substrate that has been cut out
from a primitive plate by a glass manufacturer but has not been
shipped yet, the defect remedying method of the present embodiment
is carried out as one process in a method of producing a glass
substrate.
[0069] In the following explanation, it is assumed that a glass
substrate is the one for a liquid crystal display panel and that
the defect remedying method is carried out in the stage where a
display panel constituted by use of the glass substrate has been
checked but has not been assembled as a display device yet.
Further, it is assumed herein that the internal defect is an
internal bubble. As such, the following description deals with a
method for remedying an internal bubble.
[0070] Note that, since a glass substrate which will constitute a
liquid crystal display panel contains less alkali metal and its
melting point is high, an internal bubble easily occurs. In this
regard, the defect remedying method of the present embodiment is
especially effective for the glass substrate for constituting a
liquid crystal display panel.
[0071] FIG. 2 is a cross-sectional view of a glass substrate 1 in
which an internal bubble 1b, which serves as an internal defect to
be remedied, is formed.
[0072] Since the internal bubble 1b of FIG. 2 has a relatively
large size, and its location is relatively near from a surface 1s
of the glass substrate 1, the glass substrate 1 includes a
protrusion 1p on the surface 1s. The inner bubble 1b may not cause
the protrusion 1p depending on the size and location.
[0073] The internal bubble 1b can be bubbles with various sizes
such as the one whose maximum diameter is not more than 100 .mu.m
or the one whose maximum diameter is almost the same size as a
thickness of the glass substrate 1 (for example, 0.7 mm). In a case
of the internal bubble 1b being, for example, not more than 100
.mu.m in maximum diameter, since such a small internal bubble 1b
has less effect on a display, it is considered that any special
processes may not be required. Further, in a case of the internal
bubble 1b being, for example, 100 .mu.m to 300 .mu.m in maximum
diameter, it is considered to carry out a remedying process for
making the internal bubble 1b into a black dot. However, in a case
of the internal bubble 1b being, for example, more than 300 .mu.m
in maximum diameter, there is no conceivable effective methods for
sufficiently reducing adverse effects on a display, except for the
defect remedying method of the present embodiment as described
below.
[0074] As such, the defect remedying method of the present
embodiment can be carried out with respect to the various internal
bubbles 1b from large size to small size. Among such internal
bubbles 1b, the defect remedying method of the present embodiment
is especially effective for the large-size internal bubble 1b to
which any other effective methods are hardly conceivable.
[0075] A bright dot is observed due to the internal bobble lb
formed in the glass substrate 1. Although a mechanism of how the
bright dot occurs due to such an internal bubble 1b is not
necessarily clear, the bright dot may occur from the following
reason.
[0076] In a case where a liquid crystal display panel is
constituted by the glass substrate 1 that contains the internal
bubble 1b, a lens effect is caused due to a glass around the
internal bubble 1b, or a scattered polarization state is caused due
to a residual stress of the glass around the internal bubble 1b.
Thus, a region in the vicinity of the internal bubble 1b is
observed as a bright dot.
[0077] In view of this, the defect remedying method of the present
embodiment is a method in which a glass material, from the surface
1s of the glass substrate 1 to the internal bubble 1b at least, is
removed by jetting abrasive grains toward a portion where the
internal bubble 1b, which serves as an internal defect formed in
the glass substrate 1, is located.
[0078] Further, as shown in FIG. 2, a glass material (hereinafter
referred to as "surrounding section") 1d surrounding the internal
bubble 1b is preferably removed together with the internal bubble
1b since a lens effect or a scattered polarization state may be
caused due to the surrounding section 1d.
[0079] (a) through (e) of FIG. 1 are diagrams each illustrating an
internal defect removing step according to the defect remedying
method of the present embodiment.
[0080] As shown in (a) of FIG. 1, abrasive grains 12a are jetted
toward the protrusion 1p formed on the surface 1s of the glass
substrate 1 at a predetermined jetting speed. In this case, alumina
having a grain size of No. 800 (approximately 0.03 mm (30 .mu.m))
is used as the abrasive grains 12a. However, the abrasive grains
12a are not limited to this. The abrasive grains 12a can be
selected appropriately in accordance with a type of a substrate to
be processed. Examples of the abrasive grains 12a include alumina,
cerium, and the like. In a case where the glass substrate 1 is an
object to be processed, it is preferable that alumina is used as
the abrasive grains 12a. Further, it is preferable that the
abrasive grains 12a have a grain size of 0.1 .mu.m to 100 .mu.m.
The grain size of the abrasive grains 12a used during the
brittleness processing and the grain size of the abrasive grains
12a used during the ductility processing may be different from each
other. In this case, during the brittleness processing, the grain
size of the abrasive grains 12a are made large so that processing
power is increased, whereas during the ductility processing, the
grain size of the abrasive grains 12a is made small so that
processing power is reduced.
[0081] A scanning speed (traveling speed of a remedying head 12) is
set to 0.2 mm/s to 0.6 mm/ s, but is not limited to this. The
scanning speed can be selected appropriately in accordance with a
type of a substrate to be processed. As for a jetting amount
(jetting pressure) of the abrasive grains 12a, an air of 0.8 MPa is
jetted. However, the jetting amount (jetting pressure) of the
abrasive grains 12a is not limited to this, and can be selected
appropriately in accordance with a type of a substrate to be
processed. A jetting time of the abrasive grains 12a is not limited
in particular, and can be selected appropriately in accordance with
a type of a substrate to be processed, a depth of the substrate to
be processed, and the like.
[0082] The abrasive grains 12a continue to be jetted at the above
jetting speed so that the glass material constituting the
protrusion 1p is removed until the abrasive grains 12a reach the
internal bubble 1b (see (b) of FIG. 1). The abrasive grains 12a
continue to be jetted so that the internal bubble 1b is ground away
by the abrasive grains 12a. Further, the abrasive grains 12a
continue to be jetted so that a glass material constituting the
surrounding section 1d surrounding the internal bubble 1b is
removed until a revised surface 1e is exposed, i.e., until no lens
effect and no scattered polarization state are caused (see (c) of
FIG. 1). Note that (a) through (c) of FIG. 1 are diagrams
explaining the brittleness processing. Thereafter, the abrasive
grains 12a continue to be jetted at the above jetting speed at a
shallower angle than the case shown in (b) of FIG. 1 (oblique
direction with respect to a jetting direction (substantially
vertical direction) shown in (b) of FIG. 1) (see (d) of FIG. 1). In
this state, the abrasive grains 12a continue to be jetted so that
the glass material is removed until a revised surface 1f becomes
smooth (mirror surface) (see (e) of FIG. 1). Note that (d) and (e)
of FIG. 1 are diagrams explaining the ductility processing.
[0083] The grinding process progresses by accumulation of minute
brittleness processes in which the jetted abrasive grains 12a
collide with the glass substrate 1. As such, the glass substrate 1
can be processed finely with high quality. Further, since the
grinding process progresses by switching the processing from the
brittleness processing to the ductility processing, a surface of a
processed substrate can be made smooth.
[0084] In the brittleness processing, an angle of entry of the
abrasive grains is larger than 35.degree. and not more than
90.degree. with respect to the surface 1s of the substrate 1. For
example, in a case where the substrate is a glass substrate, it is
preferable that the angle of entry of the abrasive grains is
90.degree..
[0085] Meanwhile, in the ductility processing, an angle of entry of
the abrasive grains is larger than 0.degree. and not more than
35.degree. with respect to the surface 1s of the substrate 1. For
example, in a case where the substrate is a glass substrate, it is
preferable that the angle of entry of the abrasive grains is
30.degree..
[0086] A device for achieving the defect remedying method of the
present embodiment is described below.
[0087] (a) of FIG. 3 is a cross-sectional view of a defect
remedying device 10 for carrying out the defect remedying method of
the present embodiment.
[0088] The defect remedying device 10 includes a substrate placing
table 13 which is provided on a placing surface 11a of a placing
table 11 and which fixes the glass substrate 1, which serves as an
object to be remedied, vertically with respect to ground; a head
mounting table 14 provided with a remedying head 12 for jetting the
abrasive grains 12a toward a remedied portion 1b of the glass
substrate 1 fixed on the substrate placing table 13 or toward a
reflecting plate (jetting direction changing member) 18; and a
reflecting plate mounting table 15 provided with a rotating member
16 on which a jetting direction changing member 19 including the
reflecting plate 18 and a reflecting plate supporting member 17 is
fixed.
[0089] The reflecting plate 18 preferably contains ceramics, and is
more preferably made of ceramics only. Examples of the ceramics
include silicon carbide (SiC), silicon nitride (SiN), and the like.
A material of which the reflecting plate supporting member 17 is
made is not limited to a specific one, and is, for example,
metal.
[0090] A size of the reflecting plate 18 is not limited in
particular, but it is preferable that the reflecting plate 18 has
an area of not less than 1 cm.sup.2.
[0091] The rotating member 16 causes the reflecting plate 18 to
rotate around a jetting direction of the abrasive grains 12a jetted
from the remedying head 12 (direction normal to a processed surface
of the glass substrate 1 which direction passes through the
reflecting plate 18).
[0092] The remedying head 12 is provided on the head mounting table
14 so as to be movable horizontally and vertically with respect to
the ground, and jets the abrasive grains 12a horizontally with
respect to the ground (vertically with respect to the glass
substrate 1).
[0093] The remedying head 12 includes a jetting nozzle (later
described) for jetting the abrasive grains 12a which are used to
grind the glass substrate 1. The defect remedying device 10 carries
out a grinding process as follows. Specifically, the remedying head
12 is moved so as to face the internal bubble 1b of the glass
substrate 1 or the reflecting plate 18, and then jets the abrasive
grains 12a toward the surface 1s of the glass substrate 1 or a
surface of the reflecting plate 18. In a case where the grinding
processing in which the abrasive grains 12a are jetted towards the
surface 1s of the glass substrate 1 is carried out (in a case of
the brittleness processing), the abrasive grains 12a are jetted
towards the surface 1s of the glass substrate 1 so that the
abrasive grains 12a do not make contact with (collide with) the
reflecting plate 18. Meanwhile, in a case where the grinding
processing in which the abrasive grains 12a are jetted towards the
surface of the reflecting plate 18 is carried out (in a case of the
ductility processing), the abrasive grains 12a are jetted so as to
(i) make contact with (collide with) the reflecting plate 18, (ii)
be reflected towards the glass substrate 1, and (iii) be jetted
towards the surface 1s of the glass substrate 1 at a shallow
angle.
[0094] The jetting direction changing member 19 is provided so as
to be movable on the reflecting plate mounting table 15
horizontally with respect to a circular surface (rotating surface)
of the rotating member 16 along with the rotating member 16. During
the brittleness processing, the jetting direction changing member
19 moves to a position which does not make contact with the
abrasive grains 12a jetted from the remedying head 12, whereas
during the ductility processing, the jetting direction changing
member 19 moves to a position which makes contact with the abrasive
grains 12a jetted from the remedying head 12 and changes a
direction of the abrasive grains 12a.
[0095] It is also possible that the placing table 11 is movable so
that a jetting position of the abrasive grains 12a can be adjusted
by moving the glass substrate 1 on the placing table 11.
[0096] Instead of the arrangement in which the defect remedying
device 10 includes the jetting direction changing member 19
including the reflecting plate 18 and the reflecting plate
supporting member 17, the ductility processing may be achieved by
an arrangement in which (i) a reflecting plate R (not shown) is
provided on the glass substrate 1 and (ii) the abrasive grains 12a
are jetted towards the reflecting plate R at a shallow angle so
that the abrasive grains 12a which make contact with (collide with)
the reflecting plate R are reflected in a direction in which the
reflecting plate R is not provided and is jetted towards the
surface 1s of the glass substrate 1 at a shallow angle. A tilt
angle of the reflecting plate R is adjusted in consideration of a
position on the glass substrate 1 to which the abrasive grains 12a
are jetted. This makes it possible to eliminate cloud (mirror
surface unevenness) of the surface of the glass substrate 1 which
occurs in a case where the abrasive grains 12a directly collide
with the glass substrate 1. In this case, a material of which the
reflecting plate R is made is same as that of the reflecting plate
18. Area, height, etc. of the reflecting plate R are not limited in
particular.
[0097] (b) of FIG. 3 is a plan view illustrating a substantial part
of the defect remedying device 10 for performing the defect
remedying method of the present embodiment. Specifically, (b) of
FIG. 3 is a plan view illustrating a configuration of the defect
remedying device 10 except for the substrate placing table 13, the
glass substrate 1, and the placing table 11, which plan view is
viewed from a substrate placing table 13 side. As shown in (b) of
FIG. 3, the rotating member 16 is rotated by a rotary shaft 25
provided in the reflecting plate mounting table 15. As a result,
the defect remedying device 10 can change the jetting position
(jetting direction) of the abrasive grains 12a.
[0098] (c) of FIG. 3. is a cross-sectional view illustrating a
substantial part of the defect remedying device 10 for performing
the defect remedying method of the present embodiment.
Specifically, (c) of FIG. 3 is a cross-sectional view illustrating
a configuration of the jetting direction changing member 19. As
shown in (c) of FIG. 3, a reflecting plate controlling member 27
provided in the reflecting plate supporting member 17 allows the
reflecting plate 18 to change an angle of the abrasive grains 12a
with respect to the jetting direction of the abrasive grains 12a
(direction normal to the processed surface of the glass substrate 1
which direction passes through the reflecting plate 18). As a
result, the defect remedying device 10 can change the jetting
position (jetting position, in a depth direction, in a region to be
ground) of the abrasive grains 12a.
[0099] The defect remedying method of the present embodiment can be
carried out, for example, through the following procedure. First, a
liquid crystal display panel is produced by use of a glass
substrate 1 in which a defect has not been remedied yet. While the
liquid crystal display panel is evenly irradiated by light from its
backside, it is checked whether or not a bright dot can be observed
due to an internal bubble 1b formed in the glass substrate. In a
case where the bright dot is observed, a location thereof is
specified. Then, the liquid crystal display panel is placed on the
substrate placing table 13 of the defect remedying device 10, and a
grinding process (later described) is carried out at the specified
location. In a case where a polarization plate is attached on a
surface of the glass substrate 1, it is only necessary that the
polarization plate be detached once before the grinding process is
carried out, and attached to the glass substrate 1 again after the
grinding process is completed.
[0100] FIG. 4 is a diagram schematically illustrating the remedying
head 12 provided in the defect remedying device 10.
[0101] As shown in FIG. 4, the remedying head 12 includes an
abrasive grain supplying nozzle 121 for constantly supplying the
abrasive grains 12a.
[0102] The abrasive grain supplying nozzle 121 has a cylindrical
shape, and includes a front hole 121a via which the abrasive grains
12a are ejected, a rear hole 121b via which air is supplied, and an
abrasive grain supplying hole 121c which is formed between the
front hole 121a and the rear hole 121b and via which the abrasive
grains 12a are supplied.
[0103] The abrasive grain supplying hole 121c of the abrasive grain
supplying nozzle 121 is connected to an abrasive grain tank 122 in
which the abrasive grains are stored, and the rear hole 121b is
connected to a high-speed electromagnetic valve 123.
[0104] The abrasive grain tank 122 has an opening/closing lid (not
shown) in a part where the abrasive grain tank 122 is connected to
the abrasive grain supplying nozzle 121, and the opening/closing
lid opens only while the abrasive grains 12a are being
supplied.
[0105] The high-speed electromagnetic valve 123 has (i) a
connecting cylinder 123a that connects to the rear hole 121b of the
abrasive grain supplying nozzle 121 and (ii) an air inlet hole 123b
via which air supplied from an air supplying section (not shown)
enters. The air which is supplied via the air inlet hole 123b is
supplied to the connecting cylinder 123a while the high-speed
electromagnetic valve 123 is being opened, whereas the air which is
supplied via the air inlet hole 123b is not supplied to the
connecting cylinder 123a while the high-speed electromagnetic valve
123 is being closed.
[0106] That is, according to the remedying head 12 arranged as
above, the supplied air blows the abrasive grains 12a out from the
abrasive grain supplying nozzle 121 while the high-speed
electromagnetic valve 123 is being opened and where the
opening/closing lid of the abrasive grain tank 122 is being opened.
Meanwhile, in a case where the high-speed electromagnetic nozzle
123 is closed, no abrasive grain 12a is jetted from the abrasive
grain supplying nozzle 121 regardless of whether the
opening/closing lid of the abrasive grain tank 122 is opened or
closed. In a case where the high-speed electromagnetic valve 123 is
opened and where the opening/closing lid of the abrasive grain tank
122 is closed, air which contains no abrasive grain 12a, i.e., only
air is jetted from the abrasive grain supplying nozzle 121.
[0107] The remedying head 12 arranged as above jets the abrasive
grains 12a, which are made of alumina having No. 800 of abrasive
grain size, toward the protrusion 1p of the surface 1s of the glass
substrate 1 or toward the reflecting plate at processing speed of
0.2 mm/s to 0.6 mm/s (jetting speed of 150 m/s to 200 m/s) so that
a glass material is removed until the abrasive grains 12a reach the
internal bubble 1b serving as an internal defect.
[0108] Generally, after the abrasive grains 12a continue to be
jetted from the remedying head 12 toward the surface 1a of the
glass substrate 1 or the surface of the reflecting plate, the
abrasive grains 12a remain in a portion where the grinding process
is carried out in the glass substrate 1. In such a case, newly
jetted abrasive grains 12a collide with the abrasive grains 12a
which remain in the portion, and therefore it is impossible to
cause the abrasive grains 12a to directly grind a surface which is
an actual target of the grinding process. This undesirably causes a
reduction in grinding efficiency.
[0109] In view of this, air containing the abrasive grains 12a and
only air, which serves as a medium for jetting of the abrasive
grains 12a, are alternately jetted. The abrasive grains 12a which
remain in the portion where the grinding process is carried out in
the glass substrate 1 can be removed by jetting only air. This
allows an improvement in grinding efficiency. Specifically, air
containing the abrasive grains 12a and air containing no abrasive
grain 12a can be alternately jetted by intermittently opening and
closing the opening/closing lid of the abrasive grain tank 122
while the high-speed electromagnetic valve 123 is being opened.
[0110] For example, AJM (ABRASIVE Jet Machining) produced by Sendai
Nicon Corporation can be used as the remedying head 12.
[0111] According to the defect remedying method of the present
embodiment, the removal process can be carried out until a state
shown in (e) of FIG. 1 is obtained. The state shown in (e) of FIG.
1 is not necessarily an ideal state in terms of a shape of the
glass substrate 1, but as a result of examination on an actual
influence on display, a bright dot caused by the internal bubble 1b
is less observed as compared with a state achieved before the
removal process is carried out.
[0112] Next explained is a preferable processed shape. As
illustrated in (a) FIG. 5, in a case where a recess having a steep
shape in which a part of a processed surface 1w is vertical to the
surface 1s is formed, the vertical part of the processed surface 1w
is identical with an observation direction D which is vertical to
the surface 1s. Accordingly, effects of the processed surface 1w on
a display are accumulated in the observation direction D. As a
result, this causes the processed surface 1w to be easily
observed.
[0113] In contrast, in (b) of FIG. 5, unlike the above one with a
steep shape, the processed surface 1w is not vertical to the
surface 1s, and a tangent plane (indicated by a dashed-dotted line
in (b) of FIG. 5), at any position on the processed surface 1w, is
parallel or inclined with respect to the surface 1s. Accordingly,
effects of the processed surface 1w on a display are not
accumulated in the observation direction D. As a result, the
processed surface 1w is less likely to be observed.
[0114] As such, it is preferable that the processed shape be such
that the tangent plane, at any position in the processed surface
1w, is parallel or inclined with respect to the surface 1s, as
shown in (b) of FIG. 5. In order that such the processed shape is
formed, it is only necessary that jetting speed of the abrasive
grains 12a jetted from the remedying head 12 is varied depending on
a position to be remedied. For example, in order to obtain a recess
having the shape shown in (b) of FIG. 5, the jetting speed of the
abrasive grains 12a is increased in a central portion of the
recess, and the jetting speed of the abrasive grains 12a is
gradually reduced as a distance becomes further from the central
portion.
[0115] Further, it is preferable that the recess formed in the
removal process be filled with a transparent material 2, as shown
in FIG. 6. In a case where the recess is filled with the
transparent material, a change in refractive index in the recess
can be made smaller as compared with a state where the recess is
not filled. As a result, the recess is less likely to be observed.
In order that the recess thus formed in the removal process is
filled with the transparent material 2, the recess may be filled
with a liquid transparent resin and then the liquid transparent
resin may be solidified.
[0116] According to the defect remedying device 10, alumina is used
as the abrasive grains 12a. However, the abrasive grains 12a are
not limited to this, and can be silicon carbide, boron carbide, or
cerium oxide, for example. Further, the grain size of the abrasive
grains 12a is not limited to No. 800, and therefore the abrasive
grains 12a can have other grain size. It is more preferable that
the glass substrate 1 is processed with the use of abrasive grains
having grain size of No. 800, and then the process is finished with
the use of abrasive grain having grain size of No. 2000. The grain
size of the abrasive grains 12a may vary depending on an object to
be subjected to the grinding process.
[0117] The above description has discussed a case where the glass
substrate 1 that includes the internal bubble 1b as an internal
defect is an object to be remedied, but a glass substrate 1 that
includes an internal foreign matter 1c as an internal defect as
shown in FIG. 7 may be an object to be remedied. Even in this case,
it is possible to realize a reduction in the lens effect or the
scattered polarization state. Further, in a case where the internal
foreign matter 1c is made from a light-shielding material, a
process of fully removing the internal foreign matter 1c also makes
it possible to obtain an effect that a black dot is removed.
[0118] The present embodiment has discussed an exemplary defect
remedying method in which the internal bubble 1b or the internal
foreign matter 1c formed in the glass substrate 1 is an object to
be remedied. However, the following Embodiment 2 discusses an
example in which a protrusion which serves as a surface defect
formed on the glass substrate is an object to be remedied, and is
removed by the grinding process.
Embodiment 2
[0119] Embodiment 2 of the present invention is described below.
For convenience of description, members that have identical
functions to those shown in the drawings described in Embodiment 1
are given identical reference numerals, and are not explained
repeatedly.
[0120] A defect remedying method of the present embodiment is for
remedying a defect of a glass substrate for constituting a display
panel, and the defect to be remedied is a protrusion which serves
as a surface defect formed on the glass substrate. The protrusion
may be formed due to an internal defect, as explained in Embodiment
1,or may be formed independently of such an internal defect.
[0121] As in the case of Embodiment 1, the defect remedying method
of the present embodiment can be applied to a glass substrate for
constituting various display panels such as a liquid crystal
display panel, a plasma display panel (PDP), and the like.
[0122] Moreover, as in the case of Embodiment 1, the defect
remedying method of the present embodiment can be carried out in
various stages in producing a glass substrate or a display
panel.
[0123] FIG. 8 is a cross-sectional view of a glass substrate 1 on
which a protrusion 1p serving as a surface defect to be remedied is
formed. As a device for carrying out the defect remedying method of
the present embodiment, the defect remedying device 10 explained in
Embodiment 1 can be used.
[0124] (a) through (e) of FIG. 9 each shows how a grinding process
progresses. The abrasive grains 12a are jetted by the remedying
head 12, and make contact with the protrusion 1p of the glass
substrate 1, as shown in (a) of FIG. 9. Thus, the grinding process
starts. After the abrasive grains 12a continue to be jetted, a
height of the protrusion 1p becomes lowered as shown in (b) of FIG.
9. After the abrasive grains 12a further continue to be jetted, the
protrusion 1p is fully removed as shown in (c) of FIG. 9. Note that
(a) through (c) of FIG. 9 are diagrams explaining the brittleness
processing. Thereafter, the abrasive grains 12a continue to be
jetted at the above jetting speed at a shallower angle than the
case shown in (b) of FIG. 9, as shown in (d) of FIG. 9. In this
state, the abrasive grains 12a continue to be jetted so that the
glass material is fully removed until a revised surface 1f becomes
smooth (mirror surface) as shown in (e) of FIG. 9. Note that (d)
and (e) of FIG. 9 are diagrams explaining the ductility
processing.
[0125] The grinding process progresses by accumulation of minute
brittleness processes in which the jetted abrasive grains 12a
collide with the glass substrate 1. As such, the glass substrate 1
can be processed finely with high quality. Further, since the
grinding process progresses by switching the processing from the
brittleness processing to the ductility processing, a surface of a
processed substrate can be made smooth.
[0126] According to the defect remedying method of the present
embodiment, the removal process may be carried out until the state
shown in (e) FIG. 9 is obtained. In the defect remedying method of
the present embodiment, a part or all of the protrusion 1p is
removed so that a height of the protrusion 1p is lowered. This is
referred to as planarization of the protrusion 1p. This makes it
possible to approximate the surface 1s on which the protrusion 1p
is formed, to a primary surface shape. As a result, a bright dot
due to the protrusion 1p is less likely to occur.
[0127] Note that, due to the planarization of the protrusion 1p, a
slight recess may be formed in a part where the protrusion 1p was
formed. In this case, it is preferable that a processed shape of
the recess be such that a tangent plane, at any position on a
processed surface 1w, is parallel or inclined with respect to the
surface 1s as shown in (b) of FIG. 5 in Embodiment 1. Further, it
is preferable that the recess thus formed be filled with a
transparent material 2 as shown in FIG. 6 in Embodiment 1.
[0128] As in Embodiment 1, alumina having a grain size of No. 800
may be used as the abrasive grains 12a, and the abrasive grains 12a
may be jetted at a processing speed of 0.2 mm/s to 0.6 mm/s
(jetting speed of 150 m/s to 200 m/s). Note, however, that
material, grain size, and jetting speed of the abrasive grains 12a
may be changed according to need.
[0129] As described above, the present embodiment 2 has discussed a
case where the protrusion 1p is an object to be remedied in the
glass substrate 1. However, the following Embodiment 3 discusses an
example in which a scratch on a surface 1s an object to be remedied
in the glass substrate 1.
Embodiment 3
[0130] Embodiment 3 of the present invention is described below.
For convenience of description, members that have identical
functions to those shown in the drawings described in Embodiment 1
are given identical reference numerals, and are not explained
repeatedly.
[0131] A defect remedying method of the present embodiment is a
method for remedying a defect of a glass substrate for constituting
a display panel, and the defect to be remedied is a scratch which
serves as a surface defect formed on the glass substrate.
[0132] Further, as in Embodiment 1, the defect remedying method of
the present embodiment can be applied to a glass substrate for
constituting various display panels such as a liquid crystal
display panel, a plasma display panel (PDP), and the like.
[0133] Moreover, as in Embodiment 1, the defect remedying method of
the present embodiment can be carried out in various stages in
producing a glass substrate or a display panel.
[0134] FIG. 10 is a cross-sectional view of a glass substrate 1 on
which a scratch 1v serving as a surface defect to be remedied is
formed. The defect remedying device 10 described in Embodiment 1
can be used as a device for carrying out the defect remedying
method of the present embodiment.
[0135] (a) through (d) of FIG. 11 each shows how a grinding process
progresses. The abrasive grains 12a are jetted by the remedying
head 12, and make contact with the surface 1s of the glass
substrate 1, as shown in (a) of FIG. 11. Thus, the grinding process
starts. The remedying head 12 is swayed horizontally while the
abrasive grains 12a are being jetted. This reduces an angle defined
by a surface formed due to the scratch 1v and the primary surface
1s of the glass substrate 1, as shown in (b) of FIG. 11. Note that
(a) and (b) of FIG. 11 are diagrams explaining the brittleness
processing. Thereafter, the abrasive grains 12a continue to be
jetted at the above jetting speed at a shallower angle than the
case shown in (a) of FIG. 11, as shown in (c) of FIG. 11. In this
state, the abrasive grains 12a further continue to be jetted so
that an angle defined by surfaces formed due to the scratch 1v is
reduced until a revised surface 1f becomes smooth (mirror surface)
as shown in (d) of FIG. 11. Note that (c) and (d) of FIG. 11 are
diagrams explaining the ductility processing.
[0136] The grinding process progresses by accumulation of minute
brittleness processes in which the jetted abrasive grains 12a
collide with the glass substrate 1. As such, the glass substrate 1
can be processed finely with high quality. Further, since the
grinding process progresses by switching the processing from the
brittleness processing to the ductility processing, a surface of a
processed substrate can be made smooth.
[0137] In the defect remedying method of the present embodiment,
the angle defined by the surface formed due to the scratch 1v and
the primary surface 1s of the glass substrate 1 is reduced. This is
referred to as smoothing of the scratch 1v. This makes it possible
to approximate the surface 1s on which the scratch 1v is formed, to
a primary surface shape. As a result, a bright dot due to the
scratch 1v is less likely to occur.
[0138] Note that it is preferable that a processed shape of a
recess formed by smoothing the scratch 1 be such that a tangent
plane, at any certain position on a processed surface 1w, is
parallel or inclined with respect to the surface 1s, as shown in
(b) of FIG. 5 in the Embodiment 1. Further, it is preferable that
the recess thus formed be filled with a transparent material 2 as
shown in FIG. 6 in the Embodiment 1.
[0139] FIGS. 12 shows a liquid crystal display panel 20 as a
display panel that is constituted by use of the glass substrate 1
described in Embodiments 1 through 3. (a) of FIG. 12 is a plan view
illustrating a liquid crystal display panel in an embodiment of the
present invention, and (b) of FIG. 12 is a cross-sectional view
illustrating the liquid crystal display panel.
[0140] The liquid crystal display panel 20 is arranged such that
(i) two glass substrates 1 are provided so as to face each other at
a predetermined space provided therebetween, and (ii) a liquid
crystal 21 is sandwiched between the two glass substrates 1 and is
sealed. Note that a polarization plate etc. (not shown) are
attached to external surfaces of the two glass substrates 1.
[0141] The two glass substrates 1 include, on a surface in a
display area 20a of the liquid crystal display panel 20, a
processed surface 1w which has been subjected to the glass material
removal process described in Embodiments 1 through 3. Note that
each of the two glass substrates 1 may include the processed
surface 1w, or any one of the two glass substrates 1 may include
the processed surface 1w. Further, it is preferable that the
processed surface 1w is filled with a transparent material.
[0142] In the liquid crystal display panel 20, an internal defect
or a surface defect formed in the two glass substrates 1 is
subjected to any of the removal processes described in Embodiments
1 through 3.As a result, adverse affects on a display are reduced.
On this account, even the liquid crystal display panel 20 that has
been conventionally deemed as a defective product can be produced
as a good-quality product.
[0143] Each of Embodiments 1 through 3 has discussed an example in
which the remedying head 12 provided in the defect remedying device
10 is arranged such that the abrasive grains 12a are jetted in a
horizontal direction with respect to the ground as shown in (a) of
FIG. 3. However, the present invention is not limited to this. For
example, a defect remedying device 110 may be used. In the defect
remedying device 110, a remedying head 12 is arranged such that the
abrasive grains 12a are jetted in a vertical direction with respect
to the ground (vertical direction with respect to the glass
substrate 1), as shown in FIG. 13.
[0144] The defect remedying device 110 includes a housing 111
having a placing surface 111a on which the glass substrate 1 is
placed, the remedying head 12 which is suspended from a ceiling of
the housing 111 and which is movable in horizontal and vertical
directions, and a reflecting plate mounting table 15 which is
placed in the housing 111 and which is provided with a rotating
member 16 on which a jetting direction changing member 19 including
reflecting plate 18 and a reflecting plate supporting member 17 is
fixed.
[0145] The defect remedying device 10 moves the remedying head 12
toward a position above an internal bubble 1b of the glass
substrate 1 or a position above the reflecting plate 18, and then
causes the remedying head 12 to jet the abrasive grains 12a toward
a surface 1s of the glass substrate 1 or a surface of the
reflecting plate 18 so as to carry out grinding process.
[0146] Further, according to the remedying head 12, only supply air
is supplied as shown in FIG. 4, and therefore controlling supply of
the supply air is directly linked with starting/stopping of jetting
of the abrasive grains 12a. However, in order to jet only air
containing no abrasive grain 12a, it is still necessary to control
opening/closing of the opening/closing lid of the abrasive grain
tank 122.
[0147] In view of this, FIG. 14 shows a remedying head in which it
is unnecessary to control opening/closing of the opening/closing
lid of the abrasive grain tank 122 in order to jet only air
containing no abrasive grain 12a.
[0148] A remedying head 112 shown in FIG. 14 is obtained by adding
an accelerating nozzle 124 to the remedying head 12 shown in FIG.
4. Thus, accelerating air is supplied in addition to the supply
air. Other constituents of the remedying head 112 are identical to
those of the remedying head 12 shown in FIG. 4.
[0149] The remedying head 112 is arranged such that the
accelerating nozzle 124 for accelerating the abrasive grains 12a
supplied by the abrasive grain supplying nozzle 121 is newly added,
as shown in FIG. 14.
[0150] The accelerating nozzle 124 has (i) a jetting hole 124a via
which the abrasive grains 12a are jetted toward outside, (ii) an
air supplying hole 124b via which the accelerating air, which
accelerates the abrasive grains 12a and causes the abrasive grains
12a to be jetted from the jetting hole 124a, is supplied, and (iii)
a mixing room 124c which is formed between the jetting hole 124a
and the air supplying hole 124b, in which the abrasive grains 12a
and the accelerating air are mixed, and which guides the mixture to
the jetting hole 124a.
[0151] The front hole 121a of the abrasive grain supplying nozzle
121 is disposed so as to protrude into the mixing room 124c of the
accelerating nozzle 124.
[0152] Therefore, according to the remedying head 112 arranged as
above, in a case where the high-speed electromagnetic valve 123 is
opened, the abrasive grains 12a are supplied from the abrasive
grain supplying nozzle 121 to the accelerating nozzle 124 by the
supply air, and then air containing the abrasive grains 12a is
jetted from the jetting hole 124a by the accelerating air supplied
from the air supplying hole 124b. Meanwhile, in a case where the
high-speed electromagnetic valve 123 is closed, the supply air is
not supplied to the abrasive grain supplying nozzle 121, and
therefore the abrasive grains 12a are not supplied to the
accelerating nozzle 124. Consequently, only air that contains no
abrasive grain 12a is jetted from the jetting hole 124a of the
accelerating nozzle 124.
[0153] Note that supply of the accelerating air and the supply air
is controlled so that P1<P2 is satisfied where P1 is pressure of
the accelerating air and P2 is pressure of the supply air. This
allows the abrasive grains 12a in the abrasive grain supplying
nozzle 121 to be always supplied to the accelerating nozzle 124,
and backflow of the abrasive grains 12a does not occur.
[0154] Generally, after the abrasive grains 12a continue to be
jetted from the remedying head 112 toward the surface 1a of the
glass substrate 1 or the surface of the reflecting plate 18, the
abrasive grains 12a remains in a portion that is subjected to a
grinding process. In such a case, newly jetted abrasive grains 12a
collide with the abrasive grains 12a which remain in the portion,
and therefore it is impossible to cause the abrasive grains 12a to
directly grind a surface which is an actual target of the grinding
process. This undesirably causes a reduction in grinding
efficiency.
[0155] In view of this, a pulse-shaped drive signal may be supplied
to the high-speed electromagnetic valve 124 of the remedying head
112 so that air supplied from the air inlet hole 123b is
intermittently supplied to the connecting cylinder 123a and so that
the abrasive grains 12a are intermittently supplied from the
abrasive grain supplying nozzle 121 to the accelerating nozzle 124.
According to the arrangement, air containing the abrasive grains
12a and only air, which serves as a medium for jetting of the
abrasive grains 12a, are alternately jetted. Consequently, the
abrasive grains 12a which remain in the portion that is subjected
to the grinding process can be removed by jetting only air. This
allows an improvement in grinding efficiency.
[0156] Note that, as with the remedying head 12 shown in FIG. 4,
the remedying head 112 shown in FIG. 14 can be provided in both of
the defect remedying device 10 shown in (a) of FIG. 3 and the
defect remedying device 110 shown in FIG. 13.
[0157] Each of Embodiments 1 through 3 has discussed an example in
which abrasive grains, i.e., powder is jetted with the use of air
so as to grind an object to be remedied. Note, however, that fluid,
i.e., water or the like can be jetted instead of powder so as to
grind an object to be remedied. In this case, it is only necessary
that the remedying head 12 be replaced with a head for jetting
water.
[0158] FIG. 15 is a diagram illustrating an appearance of the
surface of the glass substrate 1 achieved before and after the
grinding process in Embodiments 1 through 3 is carried out. (a) of
FIG. 15 illustrates an appearance of the surface of the glass
substrate 1 achieved before the grinding process is carried out,
and (b) of FIG. 15 illustrates an appearance of the surface of the
glass substrate 1 achieved after the grinding process is carried
out. FIG. 15 reveals that a surface of a processed substrate can be
made smooth by changing the processing from the brittleness
processing to ductility processing.
Preferable Embodiment of Present Invention
[0159] A device of the present invention for processing a substrate
may be preferably arranged to further include a rotating member for
rotating the jetting direction changing member around a normal to
the processed surface which normal passes through the jetting
direction changing member.
[0160] This allows the device of the present invention for
processing a substrate to change a direction in which the abrasive
grains are jetted after being reflected by the jetting direction
changing member.
[0161] A device of the present invention for processing a substrate
may be preferably arranged to further include a jetting direction
controlling member for controlling an angle of the jetting
direction changing member with respect to a normal to the processed
surface which normal passes through the jetting direction changing
member.
[0162] This allows the device of the present invention for
processing a substrate to control an angle at which the abrasive
grains are jetted after being reflected by the jetting direction
changing member.
[0163] A device of the present invention for processing a substrate
may be preferably arranged such that the jetting direction changing
member contains at least one of silicon carbide and silicon
nitride.
[0164] Accordingly, in the device of the present invention for
processing a substrate, the jetting direction changing member
hardly deteriorates. Consequently, it is possible to efficiently
process a substrate.
[0165] A device of the present invention for processing a substrate
may be preferably arranged such that the substrate is a glass
substrate, and the abrasive grains are made of alumina.
[0166] Alumina has hardness (Mohs hardness) of 9, and therefore can
be suitably used as abrasive grains for grinding.
[0167] A device of the present invention for processing a substrate
may be preferably arranged such that (i) jetting of the abrasive
grains and a medium for jetting the abrasive grains and (ii)
jetting of only the medium are alternately carried out.
[0168] The abrasive grains jetted towards a processed portion of
the substrate so as to grind the processed portion remain in a
portion where the grinding process is carried out. Accordingly, the
abrasive grains remaining in the portion hinder abrasive grains
jetted next from grinding the processed portion. On this account,
the longer the jetting of the abrasive grains continues, the lower
the grinding efficiency becomes. However, according to the device
for processing a substrate, (i) jetting of the abrasive grains and
a medium for jetting the abrasive grains and (ii) jetting of only
the medium are alternately carried out. This makes it possible to
alternately carry out (i) grinding of the processed portion of the
substrate and (ii) removal of a remaining substance such as
abrasive grains that remain in the portion where the grinding
process is carried out, thereby preventing unnecessary abrasive
grains from remaining in the portion. As a result, the device of
the present invention for processing a substrate can have higher
grinding efficiency.
[0169] A device of the present invention for processing a substrate
may be preferably arranged such that a processed portion of the
substrate is filled with a transparent material.
[0170] According to the device of the present invention for
processing a substrate, a portion (e.g. recess or groove) from
which the substrate is removed is filled with a transparent
material (solid substance), a change in refractive index in the
portion can be made smaller as compared with a state where the
portion is not filled. Consequently, the portion from which the
substrate is removed is less likely to be observed.
[0171] A device of the present invention for processing a substrate
may be preferably arranged such that the substrate is for
constituting a liquid crystal display panel.
[0172] Since a substrate (glass substrate) for constituting a
liquid crystal display panel contains less alkali metal and its
melting point is high, an internal bubble easily occurs. In this
regard, the device of the present invention for processing a
substrate is especially effective for a substrate for constituting
a liquid crystal display panel.
[0173] In order to attain the above object, a method of the present
invention for processing a substrate with use of the device
includes the steps of: performing brittleness processing with
respect to the substrate; and performing ductility processing with
respect to the substrate after the brittleness processing.
[0174] According to the arrangement, the ductility processing is
carried out with respect to a substrate after the brittleness
processing with the use of the above device for processing a
substrate. This makes it possible to make a surface of a processed
substrate smooth.
[0175] In order to attain the above object, a method of the present
invention for producing a processed substrate includes the step of
using the above method for processing a substrate.
[0176] According to the arrangement, it is possible to produce a
processed substrate having a smooth surface.
Other Remarks
[0177] The present invention is not limited to the description of
the embodiments above, but may be altered by a skilled person
within the scope of the claims. An embodiment based on a proper
combination of technical means disclosed in different embodiments
is encompassed in the technical scope of the present invention.
[0178] The embodiments and concrete examples of implementation
discussed in the foregoing detailed explanation serve solely to
illustrate the technical details of the present invention, which
should not be narrowly interpreted within the limits of such
embodiments and concrete examples, but rather may be applied in
many variations within the spirit of the present invention,
provided such variations do not exceed the scope of the patent
claims set forth below.
INDUSTRIAL APPLICABILITY
[0179] The present invention can be used in all fields in which a
brittle material is processed. For example, the present invention
can be applied to a glass substrate which will constitute a flat
display panel such as a liquid crystal display panel or a plasma
display panel (PDP).
REFERENCE SIGNS LIST
[0180] 1: Glass substrate (substrate)
[0181] 1a: Surface
[0182] 1b: Internal bubble (defect to be remedied, internal
defect)
[0183] 1c: Internal foreign matter (defect to be remedied, internal
defect)
[0184] 1d: Glass material
[0185] 1d: Surrounding section
[0186] 1e: Revised surface
[0187] 1f: Revised surface
[0188] 1p: Protrusion (defect to be remedied, internal defect)
[0189] 1s: surface
[0190] 1v: Scratch (defect to be remedied, internal defect)
[0191] 1w: Processed surface
[0192] 2: Transparent material
[0193] 10: Defect remedying device (processing device)
[0194] 11: Housing
[0195] 11a: Placing surface
[0196] 12: Remedying head (jetting member)
[0197] 12a: Abrasive grain
[0198] 13: Substrate placing table
[0199] 14: Head mounting table
[0200] 15: Reflecting plate mounting table
[0201] 16: Rotating member
[0202] 17: Reflecting plate supporting member
[0203] 18: Reflecting plate (jetting direction changing member)
[0204] 19: Jetting direction changing member
[0205] 20: Liquid crystal display panel
[0206] 20a: Display area
[0207] 21: Liquid crystal
[0208] 25: Rotary shaft
[0209] 27: Reflecting plate controlling member (jetting direction
controlling member)
[0210] 121: Abrasive grain supplying nozzle
[0211] 121a: Front hole
[0212] 121b: Rear hole
[0213] 121c: Abrasive grain supplying hole
[0214] 122: Accelerating nozzle
[0215] 122a: Jetting hole
[0216] 122b: Air supplying hole
[0217] 122c: Mixing room
[0218] 123: Abrasive grain tank
[0219] 124: High-speed electromagnetic valve
[0220] 124a: Connecting cylinder
[0221] 124b: Air inlet hole
* * * * *