Glass plate, laminated glass, and windshield

This glass plate has: a first main surface and a second main surface; and a first end surface and a second end surface that abut on the first main surface and the second main surface, respectively, wherein the glass plate has a wedge-shaped cross-sectional shape in which the thickness on the first end surface side is less than that on the second end surface side. The glass plate has: a first chamfered section which includes a first apical end having a curved surface shape at the first end surface; and a second chamfered section which includes a second apical end having a curved surface shape at the second end surface, and the first apical end and the second apical end are formed in the same shape.

TECHNICAL FIELD

The present invention relates to a glass plate, a laminated glass, and a windshield.

BACKGROUND ART

A glass plate is applied to a window of a vehicle such as a car. A chamfered portion is generally formed in an end surface of the glass plate in order to suppress occurrence of a defect such as chipping. In the case where the glass plate is used as a windshield, a laminated glass is used because broken pieces of the laminated glass can be prevented from easily scattering even if the laminated glass is broken, and an object flying from the front during traveling of the vehicle can be prevented from easily penetrating the laminated glass. Patent Literature 1 discloses a laminated glass in which two glass plates with chamfered portions are bonded to each other through an intermediate film.

In recent years, a head-up display (hereinafter referred to as HUD) is used as a method for displaying information for a driver of a vehicle such as a car. In the HUD, various kinds of information are displayed on a windshield. However, there is a disadvantage that when a laminated glass in which two glass plates are disposed in parallel is used as the windshield, an image displayed on the laminated glass is viewed as a double image.

Patent Literature 2 discloses a use of glasses each having a wedge shape in a sectional shape for a laminated glass in order to reduce the amount of double images.

PRIOR ART DOCUMENT

Patent Literature

SUMMARY OF THE INVENTION

Problems that the Invention is to Solve

As described above, a chamfered portion is formed in an end surface of a glass plate. The chamfered portion typically has a shape corresponding to the plate thickness thereof. When the glass plate has a wedge shape in a sectional shape, the plate thickness has a variation in its end surfaces. In this manner, for a single glass plate, when shapes of a chamfered portion in an end surface which is thick in the plate thickness and a chamfered portion in an end surface which is thin in the plate thickness are formed into different shapes corresponding to the plate thicknesses, a plurality of chamfering steps using grindstones corresponding to the shapes are required. Thus, there is a problem of poor productivity. Further, there is another problem that variation of the chamfering quality easily occur.

The present invention has been developed in consideration of such problems. An object of the present invention is to provide a glass plate, a laminated glass and a windshield, which have a chamfered portion excellent in productivity and stability of chamfering quality.

Means for Solving the Problems

A glass plate according to the present invention includes: a first main surface and a second main surface; and a first end surface and a second end surface that are adjacent to the first main surface and the second main surface, the glass plate having a wedge shape in a sectional shape in which a thickness on a first end surface side is thinner than a thickness on a second end surface side,

in which: the first end surface includes a first chamfered portion including a first tip portion having a curved surface shape; the second end surface includes a second chamfered portion including a second tip portion having the curved surface shape; and the first tip portion and the second tip portion have the same shape.

A laminated glass according to the present invention includes two or more glass plates that are bonded to each other through an intermediate film, in which at least one of the glass plates is the aforementioned glass plate.

A windshield according to the present invention includes the aforementioned laminated glass, and a resin frame that is attached to a peripheral edge portion of the laminated glass.

Advantageous Effects of the Invention

According to the present invention, it is possible to obtain a glass plate, a laminated glass and a windshield, which have a chamfered portion excellent in productivity and stability of chamfering quality.

MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described below with reference to the accompanying drawings. The present invention will be described along the following embodiments. However, the present invention can be changed by various manners without departing from the scope thereof, and other embodiments than the present embodiments may be used. Accordingly, all the changes within the scope of the present invention are included in the present application. Here, parts designated by one and the same sign in the drawings are basically similar elements with similar functions.

A glass plate according to a first embodiment will be described with reference toFIG. 1andFIG. 2.FIG. 1is a sectional view of the glass plate according to the first embodiment.FIG. 2is enlarged views of end surfaces of the glass plate inFIG. 1.

As shown inFIG. 1, a glass plate10has a first main surface12and a second main surface14, and a first end surface16and a second end surface18that are adjacent to the first main surface12and the second main surface14. The glass plate10has a wedge shape in a sectional shape in which thickness t1on the first end surface16side is thinner than thickness t2on the second end surface18side. The wedge shape means a shape whose thickness varies gradually (to be thicker or thinner) from one end side toward the other end side. The glass plate according to the first embodiment is a glass plate in which a first tip portion and a second tip portion which will be described later each have curvature radius being not larger than ½ of the thickness t1.

The thickness t1is preferably 0.5 mm or more and 2.35 mm or less, more preferably 1.0 mm or more and 2.3 mm or less, further more preferably 1.6 mm or more and 2.3 mm or less, and particularly preferably 1.8 mm or more and 2.1 mm or less. The thickness t2is preferably 0.6 mm or more and 3.35 mm or less, more preferably 1.1 mm or more and 3.3 mm or less, further more preferably 1.7 mm or more and 3.3 mm or less, and particularly preferably 1.9 mm or more and 3.1 mm or less. The thickness t1and the thickness t2of the glass plate10can be measured by a thickness gauge or the like.

A wedge angle in the sectional shape of the glass plate10is preferably 0.1 mrad or more and 0.7 mrad or less, more preferably 0.2 mrad or more and 0.6 mrad or less, and further more preferably 0.3 mrad or more and 0.6 mrad or less. The wedge angle can be calculated as an average value from the glass as a whole.

In addition, the glass plate10may include a part with a wedge angle of zero, that is, a flat part on the way from the first end surface16to the second end surface18. Further, the wedge angle does not have to be constant but may have a variation.

In the glass plate10, a first chamfered portion20is provided in the first end surface16, and a second chamfered portion22is provided in the second end surface18. In the case where the first chamfered portion20and the second chamfered portion22are provided, occurrence of a defect such as chipping can be suppressed, and damages such as flaws caused by cutting or the like can be eliminated.

In the glass plate10according to the first embodiment, the tip portion of the first chamfered portion20in the first end surface16at a side of thin plate thickness has the same shape as that of the second chamfered portion22in the second end surface18having thick plate thickness. Thus, the productivity of the glass plate10can be improved. In addition, the first chamfered portion20and the second chamfered portion22can be processed with one and the same grindstone without requiring a troublesome process. Thus, chamfering quality can be stabilized.

(A) ofFIG. 2is an enlarged view of the first end surface. The first chamfered portion20in the first end surface16has a first tip portion24having a curved surface shape, and two first outside portions26provided between the first main surface12and the first tip portion24and between the second main surface14and the first tip portion24so as to connect the first tip portion24to the first main surface12and the second main surface14respectively.

The first tip portion24has an arc shape, whose curvature radius r1is not larger than ½ of the thickness t1. Thus, the boundary portion between the chamfered portion and the non-chamfered portion can be processed easily to stabilize the quality. Each of the two first outside portions26has a flat shape or a curved surface shape. The two first outside portions26expand gradually like a tapered shape from the first tip portion24toward the first main surface12and the second main surface14. The flat shape is a linear shape or a substantially linear shape in sectional view. The curved surface shape is a shape which has a comparatively large curvature radius and is close to a substantially linear shape.

(B) ofFIG. 2is an enlarged view of the second end surface. The second chamfered portion22in the second end surface18has a second tip portion28having a curved surface shape, and two second outside portions30provided between the first main surface12and the second tip portion28and between the second main surface14and the second tip portion28so as to connect the second tip portion28to the first main surface12and the second main surface14respectively.

The second tip portion28has an arc shape, whose curvature radius r2is not larger than ½ of the thickness t1. Thus, the boundary portion between the chamfered portion and the non-chamfered portion can be processed easily to stabilize the quality. Each of the two second outside portions30has a flat shape or a curved surface shape. The two second outside portions30expand gradually like a tapered shape from the second tip portion28toward the first main surface12and the second main surface14. The flat shape is a linear shape or a substantially linear shape in sectional view. The curved surface shape is a shape which has a comparatively large curvature radius and is close to a substantially linear shape.

The shape of the first tip portion24will be compared with the shape of the second tip portion28. The curvature radius r1of the first tip portion24is equal to the curvature radius r2of the second tip portion28, and length L1of the first tip portion24is equal to length L2of the second tip portion28. The shape of the first tip portion24is the same as the shape of the second tip portion28.

Examples of the arc shape of the first tip portion24and the second tip portion28include an arc of a perfect circle and an arc of an ellipse. Although the case of an arc shape has been described above, the shape is not limited to the arc shape as long as it is a curved surface shape.

The shape of each first outside portion26will be compared with the shape of each second outside portion30. When the first outside portions26and the second outside portions30have flat shapes, an inclination angle θ1formed between the first outside portion26and the first main surface12is equal to an inclination angle θ3formed between the second outside portion30and the first main surface12. In addition, an inclination angle θ2formed between the first outside portion26and the second main surface14is equal to an inclination angle θ4formed between the second outside portion30and the second main surface14.

When the first outside portions26and the second outside portions30have curved surface shapes, the inclination angle θ1formed between the first main surface12and a straight line in contact with the first outside portion26at an intersection between the first main surface12and the first outside portion26is equal to the inclination angle θ3formed between the first main surface12and a straight line in contact with the second outside portion30at an intersection between the first main surface12and the second outside portion30. In addition, the inclination angle θ2formed between the second main surface14and a straight line in contact with the first outside portion26at an intersection between the second main surface14and the first outside portion26is equal to the inclination angle θ4formed between the second main surface14and a straight line in contact with the second outside portion30at an intersection between the second main surface14and the second outside portion30.

On the other hand, length L3of the first outside portion26on the first main surface12side is different from length L5of the second outside portion30on the first main surface12side. In addition, length L4of the first outside portion26on the second main surface14side is different from length L6of the second outside portion30on the second main surface14side. Relations L5>L3and L6>L4are established among the lengths.

A glass plate according to a second embodiment will be described with reference toFIG. 3andFIG. 4. Constituents similar to those in the glass plate according to the first embodiment will be referred by the same sign correspondingly, and description thereof may be omitted.FIG. 3is a sectional view of the glass plate according to the second embodiment.FIG. 4is enlarged views of end surfaces of the glass plate inFIG. 3.

As shown inFIG. 3, a glass plate10has a first main surface12and a second main surface14, and a first end surface16and a second end surface18that are adjacent to the first main surface12and the second main surface14. The glass plate10has a wedge shape in a sectional shape in which thickness t1on the first end surface16side is thinner than thickness t2on the second end surface18side. The glass plate according to the second embodiment is a glass plate in which a first tip portion and a second tip portion which will be described later each have curvature radius being larger than ½ of the thickness t1.

(A) ofFIG. 4is an enlarged view of the first end surface. A first chamfered portion20in the first end surface16has a first tip portion24having a curved surface shape, first outside portions26connected to the first main surface12and the second main surface14and extending to the first tip portion24, and two first transition portions32provided between the first tip portion24and the first outside portions26so as to connect the first tip portion24to the first outside portions26respectively. A curvature radius r1of the first tip portion24is larger than ½ of the thickness t1. Each of the two first outside portions26has a flat shape or a curved surface shape. The flat shape (linear shape) is preferred. It is noted that the flat shape (linear shape) includes an arc shape which can be approximated substantially to a straight line. The arc shape which can be approximated substantially to a straight line is not particularly limited. For example, the arc shape has a camber in the order of 1×10−1mm or less.

Differently from the first embodiment, the glass plate10according to the second embodiment has the first transition portions32. The curvature radius r1of the first tip portion24according to the second embodiment is larger than ½ of the thickness t1. Accordingly, the angle formed at the intersection between the first tip portion24and each first outside portion26approaches 90°. It is difficult to connect the first tip portion24to the first outside portion26smoothly. Therefore, the first transition portions32are provided so that the first tip portion24can be connected to the first outside portions26smoothly. As a result, it is excellent in productivity improvement and stability of quality. It is preferable that the curvature radius r1of the first tip portion24is smaller than 6.8 times of the thickness t1. Each first transition portion32preferably has a curved surface shape, and more preferably has an arc shape with a curvature radius smaller than that of the first tip portion24.

(B) ofFIG. 4is an enlarged view of the second end surface. A second chamfered portion22in the second end surface18has a second tip portion28having a curved surface shape, second outside portions30connected to the first main surface12and the second main surface14and extending to the second tip portion28, and two second transition portions34provided between the second tip portion28and the second outside portions30so as to connect the second tip portion28to the second outside portions30respectively. A curvature radius r2of the second tip portion28is larger than ½ of the thickness t1. Each of the two second outside portions30has a flat shape or a curved surface shape. The flat shape (linear shape) is preferred. It is noted that the flat shape (linear shape) includes an arc shape which can be approximated substantially to a straight line. The arc shape which can be approximated substantially to a straight line is not particularly limited. For example, the arc shape has a camber in the order of 1×10−1mm or less.

Differently from the first embodiment, the glass plate10according to the second embodiment has the second transition portions34. The curvature radius r2of the second tip portion28according to the second embodiment is larger than ½ of the thickness t1. Accordingly, the angle formed at the intersection between the second tip portion28and each second outside portion30approaches 90°. It is difficult to connect the second tip portion28to the second outside portion30smoothly. Therefore, the second transition portions34are provided so that the second tip portion28can be connected to the second outside portions30smoothly. Each second transition portion34preferably has a curved surface shape, and more preferably has an arc shape with a curvature radius smaller than that of the second tip portion28.

Also in the second embodiment, the shape of the first tip portion24is the same as the shape of the second tip portion28in the same manner as in the first embodiment.

The phrase “the same” in the first and second embodiments includes “the same” and “substantially the same”. The phrase “substantially the same” means a case of being regarded as equal on appearance. Based on the first end surface16side, a difference of about ±5% is allowed with respect to lengths, curvature radii, inclination angles, etc.

When the shape of the first tip portion24in the first chamfered portion20is made the same as the shape of the second tip portion28in the second chamfered portion22in the first and second embodiments, it is possible to improve the productivity and the chamfering quality in forming the chamfered portions in the glass plate10having a wedge shape in a sectional shape.

In the aforementioned embodiments, the sectional shape of the first chamfered portion20is provided so that the two first outside portions26are symmetric with respect to the first tip portion24, and the sectional shape of the second chamfered portion22is provided so that the two second outside portions30are symmetric with respect to the second tip portion28.

The present invention is not limited thereto, but the first outside portions26may be asymmetric with respect to the first tip portion24in the sectional shape of the first chamfered portion20. In the same manner, the second outside portions30may be asymmetric with respect to the second tip portion28in the sectional shape of the second chamfered portion22.

Next, a method of forming chamfered portions (the first chamfered portion20and the second chamfered portion22) in the glass plate10according to the first embodiment will be described by way of example. The glass plate10which has a wedge shape in a sectional shape having no chamfered portion formed therein is prepared. As shown inFIG. 5, the second main surface14of the glass plate10is retained on a plurality of suction pads70. The suction pads70communicate with a suction pump (not shown) through ducts disposed internally. When the suction pump is driven, the glass plate10is sucked and retained on the suction pads70.

The second end surface18of the glass plate10is chamfered by a rotary grindstone72. An annular grinding groove74extending in circumferential direction is formed in an outer circumferential surface of the rotary grindstone72. Abrasive grains of alumina, silicon carbide, diamond, etc. are contained in a wall surface of the grinding groove74. Grading (JIS-R6001) of the grain size of the abrasive grains is, for example, #120 or more and #2000 or less. The smaller the grading is, the larger the grain size is. The rotary grindstone72which is being rotated around a central line of the rotary grindstone72is moved relatively along the outer peripheral edge of the glass plate10so that at least the first end surface16and the second end surface18of the glass plate10are ground by the grinding groove74. Thus, the second chamfered portion22is formed in the second end surface18.

As shown inFIG. 5, the grinding groove74has a concave portion with an inverted shape corresponding to the shape of the second chamfered portion22. The concave portion of the grinding groove74has a curved surface shape corresponding to the curved surface shape of the second tip portion28, and flat shapes or curved surface shapes corresponding to the second outside portions30.

When the second chamfered portion22has been completely formed in the second end surface18, the rotary grindstone72is moved to the first end surface16of the glass plate10while the peripheral edge portion of the glass plate10is chamfered by the rotary grindstone72.

As shown inFIG. 6, the first end surface16of the glass plate10is chamfered by the rotary grindstone72. In the present embodiment, it is assumed that the first tip portion24of the first chamfered portion20has the same shape as the second tip portion28of the second chamfered portion22. Accordingly, by the same rotary grindstone72, the first chamfered portion20and the second chamfered portion22can be formed in the first end surface16and the second end surface18which are different in thickness in the glass plate10having a wedge shape in a sectional shape. A plurality of chamfering steps are not necessary to be performed by rotary grindstones corresponding to the thicknesses of the end surfaces. Thus, the chamfered portions can be formed efficiently in the end surfaces of the glass plate having a wedge shape in a sectional shape. In addition, the quality can be stabilized. A secondary finishing step such as a mirror-finishing step may be further performed on a chamfered portion thus formed. In addition, when the first outside portions26are made asymmetric with respect to the first tip portion24in the sectional shape of the first chamfered portion20, or when the second outside portions30are made asymmetric with respect to the second tip portion28in the sectional shape of the second chamfered portion22, processing may be performed with the rotary grindstone72in which the concave portion of the grinding groove74corresponds to the shapes to be formed. Alternatively, after processing is once performed to form symmetric shapes, additional processing may be performed to form the symmetric shapes into asymmetric shapes.

A laminated glass using a glass plate according to the present embodiment will be described with reference toFIG. 7.FIG. 7is a sectional view showing an example of the laminated glass.

As shown inFIG. 7, a laminated glass100has two glass plates110and120, and an intermediate film130which bonds the two glass plates110and120together. Each of the glass plates110and120used in the laminated glass100according to the present embodiment is a glass plate having a wedge shape in a sectional shape. The laminated glass may include two or more glass plates as long as at least one of the two or more glass plates is a glass plate having a wedge shape in a sectional shape.

A first chamfered portion112and a second chamfered portion114having the same shape in their tip portions are formed in a first end surface and a second end surface of the glass plate110. In addition, a first chamfered portion122and a second chamfered portion124having the same shape in their tip portions are formed in a first end surface and a second end surface of the glass plate120. The glass plate110and the glass plate120are disposed so that the first chamfered portion112and the second chamfered portion114face the first chamfered portion122and the second chamfered portion124respectively.

Polyvinylacetal-based resin is preferably used as the intermediate film130. Although not particularly limited, polyvinylbutyral resin (PVB) is preferably used as the polyvinylacetal-based resin because the intermediate film130thus obtained can have an excellent balance among various capacities such as excellent transparency, weathering resistance, strength, adhesive force, penetration resistance, impact energy absorption capability, moisture resistance, heat insulation properties, sound insulation properties, etc. Such a polyvinylacetal-based resin may be used alone, or two or more kinds thereof may be used together. Incidentally, the intermediate film130may be a sound insulation film in which a sound insulation layer is held between skin layers.

As shown inFIG. 7, the intermediate film130has a sectional shape with a constant thickness. That is, in the intermediate film130, a surface in contact with the glass plate110is parallel or substantially parallel to a surface in contact with the glass plate120. The thickness of the intermediate film130is preferably 0.2 mm or more and 5.2 mm or less, more preferably 0.3 mm or more and 4.0 mm or less, and further more preferably 0.4 mm or more and 3.5 mm or less.

Since the intermediate film130has a sectional shape with a constant thickness, the thickness of an end surface (on the side close to the second chamfered portions114and124of the glass plate110and the glass plate120) of the intermediate film130can be made thinner as compared with a case where an intermediate film having a wedge shape is used. Incidentally, it will go well if an intermediate film130having a wedge shape in a sectional shape is used.

A case where the laminated glass100according to the present embodiment shown inFIG. 7is used in a head-up display device will be described. Display information142emitted from a display140is reflected at a point A of the glass plate120and imaged as a displayed image (virtual image)144. Another display information146is incident on a point B of the glass plate120, and refracted to reach a point C of the glass plate110. A part of the display information146is reflected at a point C of the glass plate110, incident on the point A of the glass plate120, refracted and imaged as a displayed image148. As a result, light paths of the lights reflected at the point A and the point C to reach a driver150coincide with each other. Therefore, the displayed image144and the displayed image (virtual image)148can be visually recognized as consistent by the driver150. Thus, the amount of double images can be suppressed.

It is preferable that the intermediate film130and the glass plates110and120are arranged so as to have refractive indexes substantially equal to each other. In this manner, optical distortion can be prevented from occurring.

A windshield including a laminated glass using a glass plate according to the present embodiment will be described with reference toFIG. 8.FIG. 8is a sectional view of a main portion of the windshield.

As shown inFIG. 8, a windshield200has a laminated glass100, a resin frame202provided in a peripheral edge portion of the laminated glass100, and a double-sided adhesive tape220which bonds the resin frame202to the laminated glass100.

The laminated glass100includes a glass plate110and a glass plate120. The glass plate110is an outer glass plate which is positioned on an external side of a vehicle, and the glass plate120is an inner glass plate which is positioned on an internal side of the vehicle. The glass plate110and the glass plate120are bonded to each other through an intermediate film130.

The resin frame202is constituted by a body portion204, a flange portion206extended from the body portion204so as to support the glass plate120of the laminated glass100, a lip portion208extended from the external side surface of the body portion204, and a nip portion210brought into contact with a surface of the glass plate110of the glass100on the external side of the vehicle.

A first adhesive surface220A of the double-sided adhesive tape220is bonded to the flange portion206, and a second adhesive surface220B of the double-sided adhesive tape220is bonded to the glass plate120. Thus, the resin frame202is bonded to the peripheral edge portion of the laminated glass100through the double-sided adhesive tape220.

The windshield200is fixed to a vehicle panel (not shown) in an opening portion of a car through a bonding agent (not shown). In addition, a gap between an end portion of the laminated portion100and the vehicle body panel is sealed up by the lip portion208of the resin frame202.

An urethane bonding agent can be suitably used as the bonding agent for fixing the resin frame202to the opening portion. Flowing of the bonding agent is regulated by a dam rubber (not shown) made of rubber which is disposed between the vehicle body panel and the windshield200.

The windshield200according to the present embodiment has a configuration including the glass plates110and120each having a wedge shape in a sectional shape. Thus, the windshield200can be used suitably as a windshield supporting an HUD of a car.

The present application claims priority based on Japanese Patent Application No. 2016-235219 filed on Dec. 2, 2016, the entire contents of which are invoked herein.

REFERENCE SIGNS LIST