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.

Description

TECHNICAL FIELD

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

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.

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.

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 μm 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.

The following description deals with how a defect of a glass substrate occurs.

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.

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.

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.

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.

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).

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

Patent Literature 1

Japanese Patent Application Publication, Tokukaihei, No. 5-210074 A (Publication Date: Aug. 20, 1993)

Patent Literature 2

Japanese Patent Application Publication, Tokukai, No. 2005-189360 A (Publication Date: Jul. 14, 2005)

Patent Literature 3

Japanese Patent Application Publication, Tokukaihei, No. 6-313871 A (Publication Date: Nov. 8, 1994)

SUMMARY OF INVENTION

Technical Problem

However, the conventional substrate processing method has a problem that it is difficult to remedy a defect of a substrate.

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.

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.

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.

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.

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.

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.

However, the technique of performing brittleness processing has a problem that a surface of a processed substrate cannot be made smooth.

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.

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

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.

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.

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

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.

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

FIG. 1

FIG. 1 is a cross-sectional view showing how a grinding process in Embodiment 1 of the present invention progresses.

FIG. 2

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.

FIG. 3

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.

FIG. 4

FIG. 4 is a cross-sectional view illustrating a remedying head provided in the defect remedying device shown in FIG. 3.

FIG. 5

FIG. 5 is a cross-sectional view illustrating a shape of a processed surface obtained by the grinding process.

FIG. 6

FIG. 6 is a cross-sectional view illustrating a state where a recess formed by the grinding process is filled with a transparent material.

FIG. 7

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.

FIG. 8

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.

FIG. 9

FIG. 9 is a cross-sectional view showing how a grinding process in Embodiment 2 of the present invention progresses.

FIG. 10

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.

FIG. 11

FIG. 11 is a cross-sectional view showing how a grinding process in Embodiment 3 of the present invention progresses.

FIG. 12

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.

FIG. 13

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.

FIG. 14

FIG. 14 is a cross-sectional view illustrating another remedying head used in a defect remedying method of the present invention.

FIG. 15

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

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”.

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).

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.

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.

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.

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.

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.

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.

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.

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.

The internal bubble 1b can be bubbles with various sizes such as the one whose maximum diameter is not more than 100 μm 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 μm 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 μm to 300 μm 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 μm 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.

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.

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.

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.

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.

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.

(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.

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 μm)) 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 μm to 100 μm. 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.

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.

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.

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.

In the brittleness processing, an angle of entry of the abrasive grains is larger than 35° and not more than 90° 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°.

Meanwhile, in the ductility processing, an angle of entry of the abrasive grains is larger than 0° and not more than 35° 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°.

A device for achieving the defect remedying method of the present embodiment is described below.

(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.

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.

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.

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 cm².

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).

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).

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.

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.

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.

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.

(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.

(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.

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.

FIG. 4 is a diagram schematically illustrating the remedying head 12 provided in the defect remedying device 10.

As shown in FIG. 4, the remedying head 12 includes an abrasive grain supplying nozzle 121 for constantly supplying the abrasive grains 12a.

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.

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.

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.

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.

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.

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.

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.

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.

For example, AJM (ABRASIVE Jet Machining) produced by Sendai Nicon Corporation can be used as the remedying head 12.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

(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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

(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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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.

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.

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.

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.

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.

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.

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.

Alumina has hardness (Mohs hardness) of 9, and therefore can be suitably used as abrasive grains for grinding.

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.

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.

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.

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.

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.

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.

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.

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.

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.

According to the arrangement, it is possible to produce a processed substrate having a smooth surface.

Other Remarks

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.

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

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

1: Glass substrate (substrate)

1a: Surface

1b: Internal bubble (defect to be remedied, internal defect)

1c: Internal foreign matter (defect to be remedied, internal defect)

1d: Glass material

1d: Surrounding section

1e: Revised surface

1f: Revised surface

1p: Protrusion (defect to be remedied, internal defect)

1s: surface

1v: Scratch (defect to be remedied, internal defect)

1w: Processed surface

2: Transparent material

10: Defect remedying device (processing device)

11: Housing

11a: Placing surface

12: Remedying head (jetting member)

12a: Abrasive grain

13: Substrate placing table

14: Head mounting table

15: Reflecting plate mounting table

16: Rotating member

17: Reflecting plate supporting member

18: Reflecting plate (jetting direction changing member)

19: Jetting direction changing member

20: Liquid crystal display panel

20a: Display area

21: Liquid crystal

25: Rotary shaft

27: Reflecting plate controlling member (jetting direction controlling member)

121: Abrasive grain supplying nozzle

121a: Front hole

121b: Rear hole

121c: Abrasive grain supplying hole

122: Accelerating nozzle

122a: Jetting hole

122b: Air supplying hole

122c: Mixing room

123: Abrasive grain tank

124: High-speed electromagnetic valve

124a: Connecting cylinder

124b: Air inlet hole

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.